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1.  Dynamic Stress Factor (DySF): A Significant Predictor of Severe Hypoglycemic Events in Children with Type 1 Diabetes 
Journal of diabetes & metabolism  2012;3:10.4172/2155- 6156.1000177.
Hemoglobin A1c (HbA1c) is the current standard used in the clinical treatment of patients with diabetes. However, it has been shown that patients with similar HbA1c values may have widely different fluctuations in blood glucose values over the same period of time, including time spent in hyper- and/or hypo-glycemia. Hence, there exists a need for quantitative measures that can supplement HbA1c in managing patients with diabetes. We introduce and compare the Dynamic Stress Factor, DySF, a newly developed metric that quantifies glycemic volatility based on patient-specific glucose transition density profiles with HbA1c and with currently used glucose variability metrics in predicting severe hypoglycemia in children with type 1 diabetes. DySF, the daily weighted number of large monotonic glycemic transitions that occur within one hour, was calculated for 441 total subjects with type 1 diabetes (146 children, aged 8-14 yrs) to assess the magnitude and frequency of glucose transitions per day. Severe hypoglycemic episodes (HE) were quantified for all subjects and evaluated against HbA1c and existing measures of glucose variability, including SD, MAGE, MODD, and CONGA using logistic regression models. DySF was found to be a predictor of severe HE in children (p = 0.018) with the likelihood of a child, aged 8-14 yrs, experiencing severe hypoglycemia increasing by up to 20% with decreasing values of up to 60% of DySF. Patients of any age who had one or multiple severe hypoglycemic episodes had on average a lower DySF when compared to those with no HE. Additionally, when considering mean glucose levels, DySF/mean was a preliminary predictor of severe HE in patients with HbA1c ≤ 6.5% (p = 0.062). DySF is a dynamic, quantitative, measure of daily glucose “volatility” that separates patients, within the same strata of HbA1c, into visually distinct patient profiles. DySF can be used as a preliminary predictor of clinically severe hypoglycemia in children and “well-controlled” patients with HbA1c ≤ 6.5%.
PMCID: PMC3869027  PMID: 24349871
2.  Dynamic Stress Factor (DySF): A Significant Predictor of Severe Hypoglycemic Events in Children with Type 1 Diabetes 
Hemoglobin A1c (HbA1c) is the current standard used in the clinical treatment of patients with diabetes. However, it has been shown that patients with similar HbA1c values may have widely different fluctuations in blood glucose values over the same period of time, including time spent in hyper- and/or hypo-glycemia. Hence, there exists a need for quantitative measures that can supplement HbA1c in managing patients with diabetes. We introduce and compare the Dynamic Stress Factor, DySF, a newly developed metric that quantifies glycemic volatility based on patient-specific glucose transition density profiles with HbA1c and with currently used glucose variability metrics in predicting severe hypoglycemia in children with type 1 diabetes. DySF, the daily weighted number of large monotonic glycemic transitions that occur within one hour, was calculated for 441 total subjects with type 1 diabetes (146 children, aged 8-14 yrs) to assess the magnitude and frequency of glucose transitions per day. Severe hypoglycemic episodes (HE) were quantified for all subjects and evaluated against HbA1c and existing measures of glucose variability, including SD, MAGE, MODD, and CONGA using logistic regression models. DySF was found to be a predictor of severe HE in children (p = 0.018) with the likelihood of a child, aged 8-14 yrs, experiencing severe hypoglycemia increasing by up to 20% with decreasing values of up to 60% of DySF. Patients of any age who had one or multiple severe hypoglycemic episodes had on average a lower DySF when compared to those with no HE. Additionally, when considering mean glucose levels, DySF/mean was a preliminary predictor of severe HE in patients with HbA1c ≤ 6.5% (p = 0.062). DySF is a dynamic, quantitative, measure of daily glucose “volatility” that separates patients, within the same strata of HbA1c, into visually distinct patient profiles. DySF can be used as a preliminary predictor of clinically severe hypoglycemia in children and “well-controlled” patients with HbA1c ≤ 6.5%.
PMCID: PMC3859451  PMID: 24349871
3.  Lactobacillus acidophilus and L. reuteri modulate cytokine responses in gnotobiotic pigs infected with human rotavirus 
Beneficial Microbes  2012;3(1):33-42.
Probiotic lactic acid bacteria (LAB) have been shown to alleviate inflammation, enhance the immunogenicity of rotavirus vaccines, or reduce the severity of rotavirus diarrhoea. Although the mechanisms are not clear, the differential Th1/Th2/Th3-driving capacities and modulating effects on cytokine production of different LAB strains may be the key. Our goal was to delineate the influence of combining two probiotic strains L. acidophilus and L. reuteri on the development of cytokine responses in neonatal gnotobiotic pigs infected with human rotavirus (HRV). We demonstrated that HRV alone, or HRV plus LAB, but not LAB alone, initiated serum cytokine responses, as indicated by significantly higher concentrations of IFN-α, IFN-γ, IL-12, and IL-10 at post-inoculation day (PID) 2 in the HRV only and LAB+HRV+ pigs compared to LAB only and LAB-HRV- pigs. Peak cytokine responses coincided with the peak of HRV replication. LAB further enhanced the Th1 and Th2 cytokine responses to HRV infection as indicated by significantly higher concentrations of IL-12, IFN-γ, IL-4 and IL-10 in the LAB+HRV+ pigs compared to the LAB-HRV+ pigs. The LAB+HRV+ pigs maintained relatively constant concentrations of TGF-β compared to the HRV only group which had a significant increase at PID 2 and decrease at PID 7, suggesting a regulatory role of LAB in maintaining gut homeostasis. At PID 28, cytokine secreting cell (CSC) responses, measured by ELISpot, showed increased Th1 (IL-12, IFN-γ) CSC numbers in the LAB+HRV+ and LAB-HRV+ groups compared to LAB only and LAB-HRV- pigs, with significantly increased IL-12 CSCs in spleen and PBMCs and IFN-γ CSCs in spleen of the LAB+HRV+ group. Thus, HRV infection alone, but not LAB alone was effective in inducing cytokine responses but LAB significantly enhanced both Th1 and Th2 cytokines in HRV-infected pigs. LAB may also help to maintain immunological homeostasis during HRV infection by regulating TGF-β production.
PMCID: PMC3304463  PMID: 22348907
Lacto acid bacteria; probiotics; cytokines; human rotavirus; gnotobiotic pigs
4.  Oscillation of Clock and Clock Controlled Genes Induced by Serum Shock in Human Breast Epithelial and Breast Cancer Cells: Regulation by Melatonin 
This study investigates differences in expression of clock and clock-controlled genes (CCGs) between human breast epithelial and breast cancer cells and breast tumor xenografts in circadian intact rats and examines if the pineal hormone melatonin influences clock gene and CCG expression. Oscillation of clock gene expression was not observed under standard growth conditions in vitro, however, serum shock (50% horse serum for 2 h) induced oscillation of clock gene and CCG expression in MCF-10A cells, which was repressed or disrupted in MCF-7 cells. Melatonin administration following serum shock differentially suppressed or induced clock gene (Bmal1 and Per2) and CCG expression in MCF10A and MCF-7 cells. These studies demonstrate the lack of rhythmic expression of clock genes and CCGs of cells in vitro and that transplantation of breast cancer cells as xenografts into circadian competent hosts re-establishes a circadian rhythm in the peripheral clock genes of tumor cells.
PMCID: PMC3448497  PMID: 23012497
melatonin; clock genes; circadian; serum shock; breast cancer
5.  Genetic deficiency of aldose reductase counteracts the development of diabetic nephropathy in C57BL/6 mice 
Diabetologia  2011;54(5):1242-1251.
The aim of the study was to investigate the effects of genetic deficiency of aldose reductase in mice on the development of key endpoints of diabetic nephropathy.
A line of Ar (also known as Akr1b3)-knockout (KO) mice, a line of Ar-bitransgenic mice and control C57BL/6 mice were used in the study. The KO and bitransgenic mice were deficient for Ar in the renal glomeruli and all other tissues, with the exception of, in the bitransgenic mice, a human AR cDNA knockin-transgene that directed collecting-tubule epithelial-cell-specific AR expression. Diabetes was induced in 8-week-old male mice with streptozotocin. Mice were further maintained for 17 weeks then killed. A number of serum and urinary variables were determined for these 25-week-old mice. Periodic acid–Schiff staining, western blots, immunohistochemistry and protein kinase C (PKC) activity assays were performed for histological analyses, and to determine the levels of collagen IV and TGF-β1 and PKC activities in renal cortical tissues.
Diabetes-induced extracellular matrix accumulation and collagen IV overproduction were completely prevented in diabetic Ar-KO and bitransgenic mice. Ar deficiency also completely or partially prevented diabetes-induced activation of renal cortical PKC, TGF-β1 and glomerular hypertrophy. Loss of Ar results in a 43% reduction in urine albumin excretion in the diabetic Ar-KO mice and a 48% reduction in the diabetic bitransgenic mice (p < 0.01).
Genetic deficiency of Ar significantly ameliorated development of key endpoints linked with early diabetic nephropathy in vivo. Robust and specific inhibition of aldose reductase might be an effective strategy for the prevention and treatment of diabetic nephropathy.
Electronic supplementary material
The online version of this article (doi:10.1007/s00125-011-2045-4) contains supplementary material, which is available to authorised users.
PMCID: PMC3071933  PMID: 21267539
Aldose reductase; Collagen IV; Diabetic nephropathy; Oxidative stress; PKC; Polyol pathway; TGF-β1; Urinary albumin
7.  Cytokine Responses in Gnotobiotic Pigs after Infection with Virulent or Attenuated Human Rotavirus 
Journal of Virology  2006;80(1):372-382.
To understand the role of cytokines during rotavirus infection, we assessed the kinetics of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) (proinflammatory), IL-12 (Th1 inducer), gamma interferon (IFN-γ) (Th1), IL-4 and IL-10 (Th2), and transforming growth factor β (Th3) cytokine responses by enzyme-linked immunosorbent assay in serum and intestinal contents of neonatal gnotobiotic pigs and IL-12, IFN-γ, IL-4, and IL-10 cytokine-secreting cell (CSC) responses of mononuclear cells from ileum, spleen, and blood by ELISPOT. Pigs received the virulent Wa P1A[8]G1 strain of human rotavirus (HRV) (VirHRV), attenuated Wa HRV (AttHRV), or mock (controls). The TNF-α levels peaked earlier and remained elevated in serum of the VirHRV group but peaked later in the AttHRV group. In serum, IL-6 was significantly elevated at postinoculation day (PID) 1 in the VirHRV group and at PID 3 in both HRV groups. The IL-12 was detected in serum of all pigs including controls with significantly elevated peaks in both HRV-infected groups, indicating a role for IL-12 in the induction of immune responses to rotavirus infection. Only low and transient IFN-γ responses occurred in serum and intestinal contents of the AttHRV-infected pigs, compared to significantly higher and prolonged IFN-γ responses in the VirHRV-infected pigs. This observation coincides with the diarrhea and viremia induced by VirHRV. The number of IFN-γ-secreting cells was significantly higher in the ileum of the VirHRV group than in that of the controls. The number of IL-4 CSCs was significantly higher in ileum of both HRV groups than in that of the controls. Significantly higher levels of IL-10 in the serum occurred early in the VirHRV group, compared to lower levels in the AttHRV group. However, the number of IL-10 CSCs was significantly higher later in ileum and spleen of the AttHRV than in the VirHRV group, suggesting a delayed initiation of a Th2 response induced by AttHRV. A significantly higher percentage of pigs had IFN-γ and IL-10 responses in serum after VirHRV infection than after AttHRV infection or in controls. These data indicate a balanced Th1/Th2 response during rotavirus infection, with higher cytokine levels early after infection with VirHRV compared to that with AttHRV. Mapping the kinetics and patterns of cytokine responses after rotavirus infection has important implications for induction of protective immunity by HRV vaccines. Higher protection rates may be associated with more balanced Th1- and Th2-type responses, but induction of higher earlier IFN-γ (Th1) and proinflammatory cytokines triggered by VirHRV may also play an important role in the higher intestinal immunoglobulin A responses and protection rates induced by VirHRV.
PMCID: PMC1317545  PMID: 16352562
8.  Viremia and Nasal and Rectal Shedding of Rotavirus in Gnotobiotic Pigs Inoculated with Wa Human Rotavirus 
Journal of Virology  2005;79(9):5428-5436.
Respiratory symptoms with rotavirus shedding in nasopharyngeal secretions have been reported in children with and without gastrointestinal symptoms (Zheng et al., 1991, J. Med. Virol. 34:29-37). To investigate if attenuated and virulent human rotavirus (HRV) strains cause upper respiratory tract infections or viremia in gnotobiotic pigs, we inoculated them with attenuated or virulent HRV intranasally, intravenously, or orally or via feeding tube (gavage) and assayed virus shedding. After oral or intranasal inoculation with attenuated HRV, the pigs remained asymptomatic, but 79 to 95% shed virus nasally and 5 to 17% shed virus rectally. After inoculation by gavage, no pigs shed virus nasally or rectally, but all pigs seroconverted with antibodies to HRV. No viremia was detected through postinoculation day 10. Controls inoculated intranasally with nonreplicating rotavirus-like particles or mock inoculated did not shed virus. In contrast, 100% of pigs inoculated with virulent HRV (oral, intranasal, or gavage) developed diarrhea, shed virus nasally and rectally, and had viremia. The infectivity of sera from the viremic virulent HRV-inoculated pigs was confirmed by inoculating gnotobiotic pigs orally with pooled HRV-positive serum. Serum-inoculated pigs developed diarrhea and fecal and nasal virus shedding and seroconverted with serum and intestinal HRV antibodies. Pigs inoculated intravenously with serum or intestinal contents from the viremic virulent HRV-inoculated pigs developed diarrhea, virus shedding, and viremia, similar to the orally inoculated pigs. This study provides new evidence that virulent HRV causes transient viremia and upper respiratory tract infection in addition to gastrointestinal infection in gnotobiotic pigs, confirming previous reports of rotavirus antigenemia (Blutt et al., Lancet 362:1445-1449, 2003). Our data also suggest that intestinal infection might be initiated from the basolateral side of the epithelial cells via viremia. Additionally, virus shedding patterns indicate a different pathogenesis for attenuated versus virulent HRV.
PMCID: PMC1082764  PMID: 15827157
9.  Antibody-Secreting Cell Responses to Rotavirus Proteins in Gnotobiotic Pigs Inoculated with Attenuated or Virulent Human Rotavirus 
Journal of Clinical Microbiology  2001;39(8):2807-2813.
Because of their similarities to infants in mucosal immune responses and their susceptibility to human rotavirus (HRV) diarrhea, gnotobiotic pigs provide a useful model for rotaviral disease. In this study, we performed quantitative enzyme-linked immunospot (ELISPOT) assays to measure local and systemic isotype-specific antibody-secreting cell (ASC) responses to individual structural (VP4, VP6, and VP7) and nonstructural (NSP3 and NSP4) proteins of Wa HRV. The Spodoptera frugiperda cells expressing each recombinant baculovirus HRV protein were formalin fixed and used as antigen for ELISPOT assays. Neonatal gnotobiotic pigs were orally inoculated once with virulent Wa (WaV) or three times with attenuated Wa (WaA) HRV or mock inoculated (Mock) and then were challenged with virulent Wa (WaV/PC) 28 days after the first inoculation. The ASCs from intestinal and systemic lymphoid tissues of pigs from each group were quantitated by ELISPOT assay at the day of challenge, at postinoculation day 28 (WaV, WaA, and Mock) or at postchallenge day (PCD) 7 (WaV+WaV/PC, WaA+WaV/PC, and Mock+WaV/PC). In all virus-inoculated pigs, regardless of the inoculum, lymphoid tissue, or isotype, VP6 induced the highest numbers of ASCs, followed by VP4; ASCs specific for VP7, NSP3, and NSP4 were less numerous. At challenge, total HRV- and HRV protein-specific immunoglobulin A (IgA) and IgG ASCs in intestinal lymphoid tissues were significantly greater in WaV- than in WaA-inoculated pigs, and WaV pigs were fully protected against diarrhea postchallenge, whereas the WaA pigs were partially protected. At PCD 7, there were no significant differences in ASC numbers for any HRV proteins between the WaV+WaV/PC and WaA+WaV/PC groups.
PMCID: PMC88243  PMID: 11473996
10.  Outcome of pulmonary tuberculosis treatment in the tertiary care setting -- Toronto 1992/93 
BACKGROUND: Completion of treatment of active cases of tuberculosis (TB) is the most important priority of TB control programs. This study was carried out to assess treatment completion for active cases of pulmonary TB in Toronto. METHODS: Consecutive cases of culture-proven pulmonary TB were obtained from the microbiology laboratories of 5 university-affiliated tertiary care centres in Toronto in 1992/93. A standard data-collection tool was used to abstract information from inpatient and outpatient charts. For patients who were transferred to other treatment centres or lost to follow-up, the local health unit was contacted for information about treatment completion. If incomplete information was obtained from these sources, data from the provincial Reportable Disease Information System were also reviewed. The main outcome analysed was treatment outcome, with cases classified as completed (record of treatment completion noted), transferred (patient transferred to another centre but no treatment results available), defaulted (record of defaulting in patient chart but no record of treatment completion elsewhere, or patient still receiving treatment more than 15 months after diagnosis) or dead (patient died before treatment completion). RESULTS: Of the 145 patients 84 (58%) completed treatment, 25 (17%) died, 22 (15%) defaulted and 14 (10%) were transferred. The corresponding values for the 22 patients with HIV coinfection were 6 (27%), 5 (23%), 8 (36%) and 3 (14%). Independent predictors of failure to complete treatment were injection drug use (adjusted odds ratio [OR] 5.7, 95% confidence interval [CI] 1.5 to 22.0), HIV infection (adjusted OR 4.6, 95% CI 1.4 to 14.7) and adverse drug reaction (adjusted OR 2.9, 95% CI 1.1 to 7.9). Independent predictors of death included age more than 50 years (adjusted OR 16.7, 95% CI 2.6 to 105.1), HIV infection (adjusted OR 16.1, 95% CI 3.9 to 66.4), immunosuppressive therapy (adjusted OR 8.0, 95% CI 1.9 to 34.4) and infection with a multidrug-resistant organism (adjusted OR 30.7, 95% CI 1.5 to 623.0). INTERPRETATION: Treatment completion rates in tertiary care hospitals in Toronto in 1992/93 were below the rate recommended by the World Health Organization. Careful surveillance of treatment completion is necessary for the management of TB in metropolitan centres in Canada.
PMCID: PMC1230157  PMID: 10189422
11.  Prevalence of Mycobacterium tuberculosis infection among injection drug users in Toronto 
BACKGROUND: Injection drug users are at increased risk of Mycobacterium tuberculosis infection and active tuberculosis (TB). The primary objective of this study was to determine the prevalence of M. tuberculosis infection among injection drug users in Toronto, as indicated by a positive tuberculin skin test result. An additional objective was to identify predictors of a positive skin test result in this population. METHODS: A cross-sectional study was carried out involving self-selected injection drug users in the city of Toronto. A total of 171 participants were recruited through a downtown Toronto needle-exchange program from June 1 to Oct. 31, 1996. RESULTS: Of 167 subjects tested, 155 (92.8%) returned for interpretation of their skin test result within the designated timeframe (48 to 72 hours). Using a 5-mm cut-off, the prevalence rate of positive tuberculin skin test results was 31.0% (95% confidence interval 23.8% to 38.9%). Birth outside of Canada and increasing age were both predictive of a positive result. INTERPRETATION: There is a high burden of M. tuberculosis infection in this population of injection drug users. The compliance observed with returning for interpretation of skin test results indicates that successful TB screening is possible among injection drug users.
PMCID: PMC1230158  PMID: 10189423
12.  Effects of Maternal Antibodies on Protection and Development of Antibody Responses to Human Rotavirus in Gnotobiotic Pigs 
Journal of Virology  1999;73(1):186-197.
Although maternal antibodies can protect against infectious disease in infancy, they can also suppress active immune responses. The effects of circulating maternal antibodies, with and without colostrum and milk antibodies, on passive protection and active immunity to human rotavirus (HRV) were examined in gnotobiotic pigs. Pigs received intraperitoneal injections of high-titer serum (immune pigs [groups 1 and 2]) from immunized sows, low-titer serum from naturally infected sows (control pigs [groups 3 and 4]), or no serum (group 5). Immune or control colostrum and milk were added to the diet of groups 2 and 4, respectively. After inoculation (3 to 5 days of age) and challenge (postinoculation day [PID] 21) with virulent HRV, the effects of maternal antibodies on protection (from diarrhea and virus shedding), and on active antibody responses (measured by quantitation of antibody-secreting cells [ASC] in intestinal and systemic lymphoid tissues by ELISPOT) were evaluated. Groups 1 and 2 had significantly less diarrhea and virus shedding after inoculation but higher rates of diarrhea and virus shedding after challenge than did groups 3 and 5. Group 1 and 2 pigs had significantly fewer immunoglobulin A (IgA) ASC in intestinal tissues at PID 21 and at postchallenge day (PCD) 7 compared to group 5. Significantly fewer IgG ASC were present in the intestines of group 2 pigs at PID 21 and PCD 7 compared to group 5. There was a trend towards fewer ASC in intestinal tissues of group 2 than group 1, from PID 21 on, with significantly fewer IgA ASC at PCD 7. IgG ASC in the duodenum and mesenteric lymph nodes of group 3 and 4 pigs were significantly fewer than in group 5 at PCD 7. These decreases in ASC emphasize the role of passive antibodies in impairing induction of ASC rather than in merely suppressing the function of differentiated B cells. To be successful, vaccines intended for populations with high titers of maternal antibodies (infants in developing countries) may require higher titers of virus, multiple doses, or improved delivery systems, such as the use of microencapsulation or immune stimulating complexes, to overcome the suppressive effects of maternal antibodies.
PMCID: PMC103822  PMID: 9847321
13.  A sequential treatment regimen with melatonin and all-trans retinoic acid induces apoptosis in MCF-7 tumour cells. 
British Journal of Cancer  1998;77(12):2129-2137.
Neoplastic events are marked by uncontrolled cell proliferation. One major focus of cancer research has been to identify treatments that reduce or inhibit cell growth. Over the years, various compounds, both naturally occurring and chemically synthesized, have been used to inhibit neoplastic cell proliferation. Two such oncostatic agents, melatonin and retinoic acid, have been shown to suppress the growth of hormone-responsive breast cancer. Currently, separate clinical protocols exist for the administration of retinoids and melatonin as adjuvant therapies for cancer. Using the oestrogen receptor (ER)-positive MCF-7 human breast tumour cell line, our laboratory has studied the effects of a sequential treatment regimen of melatonin followed by all-trans retinoic acid (atRA) on breast tumour cell proliferation in vitro. Incubation of hormonally responsive MCF-7 and T47D cells with melatonin (10(-9) M) followed 24 h later by atRA (10(-9) M) resulted in the complete cessation of cell growth as well as a reduction in the number of cells to below the initial plating density. This cytocidal effect is in contrast to the growth-suppressive effects seen with either hormone alone. This regimen of melatonin followed by atRA induced cytocidal effects on MCF-7 cells by activating pathways leading to apoptosis (programmed cell death) as evidenced by decreased ER and Bcl-2 and increased Bax and transforming growth factor beta 1 (TGF-beta1) expression. Apoptosis was reflected morphologically by an increase in the number of lysosomal bodies and perinuclear chromatin condensation, cytoplasmic blebbing and the presence of apoptotic bodies. The apoptotic effect of this sequential treatment with melatonin and atRA appears to be both cell and regimen specific as (a) ER-negative MDA-MB-231 and BT-20 breast tumour cells were unaffected, and (b) the simultaneous administration of melatonin and atRA was not associated with apoptosis in any of the breast cancer cell lines studied. Taken together, the results suggest that use of an appropriate regimen of melatonin and atRA should be considered for preclinical and clinical evaluation against ER-positive human breast cancer.
PMCID: PMC2150391  PMID: 9649124
14.  Development of two monoclonal antibodies against Plasmodium falciparum sporozoite surface protein 2 and mapping of B-cell epitopes. 
Infection and Immunity  1997;65(8):3430-3437.
The Plasmodium yoelii sporozoite surface protein 2 (PySSP2) is the target of protective cellular immunity. Cytotoxic T cells specific for the Plasmodium falciparum analog PfSSP2, also known as thrombospondin-related anonymous protein (TRAP), are induced in human volunteers immunized with irradiated sporozoites. PfSSP2 is an important candidate antigen for a multicomponent malaria vaccine. We generated and characterized three monoclonal antibodies (MAbs) specific for PfSSP2/TRAP. The MAbs PfSSP2.1 (immunoglobulin G1 [IgG1]), PfSSP2.2 (IgG2a), and PfSSP2.3 (IgM) were species specific and identified three distinct B-cell epitopes containing sequences DRYI, CHPSDGKC, and TRPHGR, respectively. PfSSP2.1 partially inhibited P. falciparum liver-stage parasite development in human hepatocyte cultures (42 and 86% in two experiments at 100 microg/ml). Mice immunized with vaccinia virus expressing full-length PfSSP2 protein produced antibodies to (DRYIPYSP)3, and humans living in malaria-endemic areas (Indonesia and Kenya), who have lifelong exposure and partial clinical immunity to malaria, had antibodies to both (DRYIPYSP)3 and (CHPSDGKCN)2. Mice immunized with multiple antigen peptides MAP4 (DRYIPYSP)3P2P30 and MAP4 (CHPSDGKCN)3P2P30 in TiterMax developed antibodies to sporozoites that partially inhibited sporozoite invasion of human hepatoma cells (39 to 71% at a serum dilution of 1:50 in three different experiments). The modest inhibitory activities of the MAbs and the polyclonal antibodies to PfSSP2/TRAP epitopes do not suggest that a single-component vaccine designed to induce antibodies against PfSSP2/TRAP will be protective. Nonetheless, the MAbs directed against PfSSP2, and the peptides recognized by these MAbs, will be essential reagents in the development of PfSSP2/TRAP as a component of a multivalent P. falciparum human malaria vaccine.
PMCID: PMC175485  PMID: 9234808
15.  Diphtheria and tetanus immunity among blood donors in Toronto 
OBJECTIVE: To determine the diphtheria and tetanus antitoxin levels among blood donors in Toronto. DESIGN: Cross-sectional seroprevalence study. SETTING: Two fixed-site blood-donation clinics in Toronto from September to November 1994. PARTICIPANTS: Blood donors 20 years of age or older were eligible to participate; of the 781 eligible donors, 710 (90.9%) participated in the study. MAIN OUTCOME MEASURES: Diphtheria and tetanus antitoxin levels and factors associated with disease susceptibility, such as vaccination history, country of birth, age and sex. A diphtheria antitoxin level lower than 0.01 lU/mL and a tetanus antitoxin level lower than 0.15 lU/mL were considered nonprotective. RESULTS: Among the participants, 147 (20.7%) had a diphtheria antitoxin level in the nonprotective range, and 124 (17.5%) had a tetanus antitoxin level that was nonprotective. Increasing age and lack of written vaccination records were associated with susceptibility to the 2 diseases. Birth outside Canada was significantly related to tetanus susceptibility. CONCLUSION: Adults over 50 years of age who did not know their vaccination history were the least likely to be protected against diphtheria and tetanus. The greatest benefit of any immunization strategy would be gained by targeting this group.
PMCID: PMC1227163  PMID: 9099166
16.  Family physicians managing tuberculosis. Qualitative study of overcoming barriers. 
Canadian Family Physician  1997;43:649-655.
OBJECTIVE: To identify the types of non-clinical barriers family physicians face in the management of TB, and to suggest strategies for overcoming these barriers. DESIGN: Qualitative study based on focus group discussions with family physicians and specialists in different types of practices. SETTING: Private practices, community health centres, and family practice units in hospitals. PARTICIPANTS: Family physicians and specialists working in different practice settings. METHOD: At least one specialist participated in each focus group in order to understand possible differences in non-clinical barriers to TB management between family physicians and specialists. MAIN FINDINGS: Physicians can identify many types of non-clinical obstacles to TB management. Some obstacles appear to be directly related to the organization of family practice medicine, while others stem from the type of patient population seen or the stigma associated with TB. Some physicians question whether or not patient "noncompliance" is in fact a barrier to TB management. Many family physicians believe that they have readily available to them the expert opinion needed to manage TB effectively. CONCLUSIONS: Some specific interventions, such as changes in TB guidelines, could overcome some of the obstacles identified. Differences among family physicians in the organization and nature of their practice, and in their understanding of their role in TB management, however, should be taken into account in developing interventions because such differences could influence both the need for, and receptivity to, any changes.
PMCID: PMC2255495  PMID: 9111981
17.  Outer membrane protein of Neisseria meningitidis as a mucosal adjuvant for lipopolysaccharide of Brucella melitensis in mouse and guinea pig intranasal immunization models. 
Infection and Immunity  1996;64(12):5263-5268.
A mucosal vaccine against brucellosis consisting of the lipopolysaccharide (LPS) of Brucella melitensis complexed with the outer membrane protein (GBOMP) of group B Neisseria meningitidis was tested in small-animal models of intranasal immunization. Mice given two doses of the vaccine developed high levels of immunoglobulin G (IgG) and IgA antibodies specific for B. melitensis LPS in lung lavages and specific IgG and IgA antibody-secreting cells in the lungs and spleen. Similarly, in guinea pigs immunized twice intranasally, IgG and IgA LPS-specific antibodies were detected in lung lavages, and specific antibody-secreting cells were isolated from the spleen and cervical nodes. In mice immunized with LPS only, pulmonary responses consisted mostly of IgM antibodies, while guinea pigs given LPS alone developed local antibody of all three isotypes, but at lower levels compared to animals given the complex vaccine. Both mice and guinea pigs also developed high levels of serum IgG and moderate levels of IgA as a result of intranasal immunization with the complex vaccine. The serum antibodies in both cases were found to cross-react with the LPS of B. abortus, which shares an immunogenic epitope with B. melitensis LPS. In mice given the complex vaccine, there was a prominent serum IgG1 response that was absent in the mice given LPS alone. In conclusion, the N. meningitidis GBOMP was an effective mucosal adjuvant for secretory IgA and IgG responses in the lungs of both mice and guinea pigs. The IgG1 subclass response in mice suggests that GBOMP may have favored a Th2 type of response to the LPS. A vaccine capable of stimulating high levels of antibody at local sites has the potential to protect against brucellae, since these pathogens gain entry to the host via mucosal routes.
PMCID: PMC174517  PMID: 8945575
18.  Transforming growth factor beta 1 (TGF-beta 1) produced in tumour tissue after chemotherapy acts as a lymphokine-activated killer attractant. 
British Journal of Cancer  1996;74(2):274-279.
Using an under agarose migration (UAM) assay, we studied lymphokine-activated killer (LAK)-attractant activity in cultured conditioned medium of tumour tissues after chemotherapy as a possible mechanism of enhanced LAK cell accumulation into tumour tissues after chemotherapy. BMT-11 is a fibrosarcoma developed in C57BL/6 mice. The conditioned medium of BMT-11 tumour tissues obtained from mice treated with various anti-cancer drugs had chemotactic activity for LAK cells (LAK-attractant activity). mRNA expression of interleukin (IL)-1 alpha, IL-6, IL-8, interferon (IFN)-gamma, and tumour necrosis factor (TNF)-alpha was observed in untreated tumour tissues, which were not enhanced by cyclophosphamide treatment. mRNA expression of TGF-beta 1 was not detected in untreated tumour tissues by reverse transcription-polymerase chain reaction (RT-PCR), but was detected in tumour tissues treated with cyclophosphamide. Recombinant human TGF-beta 1 showed LAK-attractant activity at a concentration of 0.1 ng ml-1 and 1 ng ml-1, whereas fresh splenocytes were not attracted by TGF-beta 1. Anti-TGF-beta 1 antibody inhibited LAK-attractant activity in the conditioned medium of tumour tissues treated with cyclophosphamide to approximately 35% that of control at 100 micrograms ml-1. These findings indicate that TGF-beta 1 produced in the tumour tissues of mice treated with anti-cancer drugs could be a LAK attractant. By a 4 h 51Cr release assay of natural killer cell-resistant BMT-11 tumour cells, we observed that TGF-beta 1 at a concentration from 0.01 ng ml-1 to 10 ng ml-1 did not inhibit LAK activity in an effector phase. Taken together, we suggest that TGF-beta 1 produced in tumour tissues after chemotherapy participates in gathering transferred LAK cells and contributes to the therapeutic effects of transferred LAK cells.
PMCID: PMC2074585  PMID: 8688335
19.  Deletion of purE attenuates Brucella melitensis infection in mice. 
Infection and Immunity  1996;64(6):2188-2192.
We previously showed that a purE mutant (delta purE201) of Brucella melitensis 16M is attenuated for growth in cultured human monocytes (E. S. Drazek, H. H. Houng, R. M. Crawford, T. L. Hadfield, D. L. Hoover, and R. L. Warren, Infect. Immun. 63:3297-3301, 1995). To determine if this strain is attenuated in animals, we compared the growth of the delta purE201 mutant with that of strain 16M in BALB/c mice. The number of bacteria in the spleen and spleen weight peaked for both strains between 1 and 2 weeks postinfection (p.i.), though the number of delta purE201 cells was significantly less than the number of 16M cells recovered from the spleens of infected mice. During the next 6 weeks, delta purE201 was essentially eliminated from infected mice (three of five mice sterile; < 100 CFU in two of live mice at 8 weeks p.i.), whereas bacteria persisted at a high level in the spleens of 16M-infected mice (about 106 CFU per spleen). The number of bacteria in the livers and lungs of mice infected with either strain paralleled those in the spleen. Mice infected with 16M had a strong inflammatory response, developing dramatic and prolonged splenomegaly (five to eight times normal spleen weight) and producing serum interleukin-6. In contrast, mice infected with delta purE201 developed only mild, transient splenomegaly at 1 week p.i. and produced no interleukin-6 in their serum. We further characterized the host response to infection by measuring changes in immune spleen cell populations by flow cytometry. CD4- and CD8-positive lymphocytes declined by I week in both experimental groups, while MAC-1-positive cells increased. T-cell subpopulations remained low or declined further, and MAC-1 cells increased to three times normal levels during 8 weeks of infection with 16M but returned to normal by 4 weeks after infection with delta purE201. These results document infectivity and attenuation of delta purE201 and suggest that it should be further evaluated as a potential vaccine.
PMCID: PMC174054  PMID: 8675325
20.  Systematic and intestinal antibody-secreting cell responses and correlates of protective immunity to human rotavirus in a gnotobiotic pig model of disease. 
Journal of Virology  1996;70(5):3075-3083.
Neonatal gnotobiotic pigs orally inoculated with virulent (intestinal-suspension) Wa strain human rotavirus (which mimics human natural infection) developed diarrhea, and most pigs which recovered (87% protection rate) were immune to disease upon homologous virulent virus challenge at postinoculation day (PID) 21. Pigs inoculated with cell culture-attenuated Wa rotavirus (which mimics live oral vaccines) developed subclinical infections and seroconverted but were only partially protected against challenge (33% protection rate). Isotype-specific antibody-secreting cells (ASC were enumerated at selected PID in intestinal (duodenal and ileal lamina propria and mesenteric lymph node [MLN]) and systemic (spleen and blood) lymphoid tissues by using enzyme-linked immunospot assays. At challenge (PID 21), the numbers of virus-specific immunoglobulin A (IgA) ASC, but not IgG ASC, in intestines and blood were significantly greater in virulent-Wa rotavirus-inoculated pigs than in attenuated-Wa rotavirus-inoculated pigs and were correlated (correlation coefficients: for duodenum and ileum, 0.9; for MLN, 0.8; for blood, 0.6) with the degree of protection induced. After challenge, the numbers of IgA and IgG virus-specific ASC and serum-neutralizing antibodies increased significantly in the attenuated-Wa rotavirus-inoculated pigs but not in the virulent-Wa rotavirus-inoculated pigs (except in the spleen and except for IgA ASC in the duodenum). The transient appearance of IgA ASC in the blood mirrored the IgA ASC responses in the gut, albeit at a lower level, suggesting that IgA ASC in the blood of humans could serve as an indicator for IgA ASC responses in the intestine after rotavirus infection. To our knowledge, this is the first report to study and identify intestinal IgA ASC as a correlate of protective active immunity in an animal model of human-rotavirus-induced disease.
PMCID: PMC190169  PMID: 8627786
21.  Development of mucosal and systemic lymphoproliferative responses and protective immunity to human group A rotaviruses in a gnotobiotic pig model. 
Gnotobiotic pigs were orally inoculated with virulent Wa strain (G1P1A[8]) human rotavirus (group 1), attenuated Wa rotavirus (group 2) or diluent (controls) and were challenged with virulent Wa rotavirus 21 days later. On various postinoculation or postchallenge days, virus-specific responses of systemic (blood and spleen) and intestinal (mesenteric lymph node and ileal lamina propria) mononuclear cells (MNC) were assessed by lymphoproliferative assays (LPA). After inoculation, 100% of group 1 pigs and 6% of group 2 pigs shed virus. Diarrhea occurred in 95, 12, and 13% of group 1, group 2, and control pigs, respectively. Only groups 1 and 2 developed virus-specific LPA responses prior to challenge. Group 1 developed significantly greater mean virus-specific LPA responses prior to challenge and showed no significant changes in tissue mean LPA responses postchallenge, and 100% were protected against virulent virus challenge. By comparison, both group 2 and controls had significantly lower LPA responses at challenge and both groups showed significant increases in mean LPA responses postchallenge. Eighty-one percent of group 2 and 100% of control pigs shed challenge virus, and both groups developed diarrhea that was similar in severity postchallenge. The virus-specific LPA responses of blood MNC mirrored those of intestinal MNC, albeit at a reduced level and only at early times postinoculation or postchallenge in all pigs. In a separate study evaluating antibody-secreting-cell responses of these pigs (L. Yuan, L.A. Ward, B.I. Rosen, T.L. To, and L.J. Saif, J. Virol. 70:3075-3083, 1996), we found that the magnitude of a tissue's LPA response positively correlated with the numbers of virus-specific antibody-secreting cells for that tissue, supporting the hypothesis that the LPA assesses T-helper-cell function. The magnitude of LPA responses in systemic and intestinal tissues also strongly correlated with the degree of protective immunity elicited by the inoculum (p = 0.81). We conclude that blood may provide a temporary "window" for monitoring intestinal T cells and that the LPA can be used to assess protective immunity to human rotaviruses.
PMCID: PMC170344  PMID: 8705681
22.  Evaluation of a tuberculosis screening program for high-risk students in Toronto schools. 
OBJECTIVE: To evaluate the effectiveness of a tuberculosis (TB) screening program for high-risk students in elementary and secondary schools. DESIGN: Cross-sectional study of the 1992-93 school screening program conducted by the Department of Public Health of the City of Toronto. Program costs were calculated with the use of 1993 wages, and costs for medical care were based on the 1993 fee schedule of the Ontario Medical Association. SETTING: Elementary and secondary schools in the City of Toronto. PARTICIPANTS: Students enrolled for the first time in any grade who were born in a country where TB is endemic or who were aboriginal Canadians were eligible. Of 44,179 students in Toronto schools 1775 met the eligibility criteria. INTERVENTION: Students were administered a Mantoux skin test, and those with a significant reaction (an induration of 10 mm or more in diameter) were advised to consult a physician for follow-up. OUTCOME MEASURES: Participation rate, number of participants with a significant reaction, percentage of these who were prescribed isoniazid and who completed chemoprophylaxis, potential number of preventable cases and costs associated with preventing each case. RESULTS: Of 1775 eligible students 42.9% (761) agreed to participate, and 40.6% (720) were screened. Significant skin-test reactions were detected in 22.5% (162/720) of the participants screened. Of these, 87.7% (142/162) saw a physician; subsequently, 2 cases of TB (1 active and 1 inactive) were detected. Of the remaining 140 students 44.3% (62) were prescribed isoniazid, of whom 9.7% (6/62) refused chemoprophylaxis. Of the remaining 56 students 82.1% (46) completed at least 6 months of chemoprophylaxis and 10.7% (6) were completing treatment at the end of the study. An estimated 3.2 cases were prevented, at a cost of $13,493.15 per case, whereas the undiscounted cost of treatment for an uncomplicated active case of TB in a patient under 19 years of age was $4503.82. CONCLUSIONS: The effectiveness of this screening program was significantly reduced by poor participation and poor rates of prescription of isoniazid by physicians. Appropriate strategies are needed to reduce barriers to the implementation of these programs.
PMCID: PMC1487346  PMID: 7553494
23.  The importance of a lipopolysaccharide-initiated, cytokine-mediated host defense mechanism in mice against extraintestinally invasive Escherichia coli. 
Journal of Clinical Investigation  1995;96(2):676-686.
Extraintestinally invasive Escherichia coli (EC) that possess both a complete LPS and K1 capsule evade both complement-mediated bacteriolysis and neutrophil-mediated killing. Since C3H/HeJ mice that are hyporesponsive to LPS were uniquely susceptible to lethal infection with EC of this phenotype, we speculated there was an LPS-initiated host defense mechanism against this pathogenic phenotype. The LPS-normoresponsive C3H/HeN as well as the C3H/HeJ mice cleared these EC from the circulation within 4 h of intravenous administration. Whereas electron micrographs of the liver demonstrated these EC undergoing degeneration within the phagolysosomes of of both macrophages and Kupffer cells of C3H/HeN mice, these EC replicated within these cells of the C3H/HeJ mice. Restoration of anti-EC activity of C3H/HeJ mice occurred with activation of Kupffer cells and peritoneal macrophages in vivo with BCG and in vitro with IFN-gamma, but not with LPS. Pretreatment of C3H/HeJ mice with a combination of recombinant murine IL-1 and TNF-alpha also restored the killing of K1(+)-EC but did not enhance the killing of a K1(-)-EC mutant. These data are consistent with the hypothesis that (a) there is no intrinsic inability of C3H/HeJ phagocytes to kill EC, but (b) an LPS-initiated, cytokine-mediated host defense mechanism is required for such killing. These studies emphasize the importance of bacterial surface characteristics in the interaction with specific host defenses.
PMCID: PMC185248  PMID: 7635960
24.  Vaccine storage and handling. Knowledge and practice in primary care physicians' offices. 
Canadian Family Physician  1995;41:1169-1176.
OBJECTIVE: To assess the knowledge and practice of vaccine storage and handling in primary care physicians' offices. DESIGN: A cross-sectional study was conducted from August to December 1992. Staff responsible for vaccine storage were interviewed about their knowledge and practices of vaccine handling and storage. Refrigerators were inspected to document refrigerator temperature and vaccine storage conditions. SETTING: General and pediatric practices in 12 regions of Ontario. PARTICIPANTS: Practices outside metropolitan Toronto were selected by choosing every 10th physician who ordered vaccine from the local health department in 1992. Practices chosen in metropolitan Toronto were a random selection of physicians affiliated with a Toronto teaching hospital. Eighteen pediatric and 138 general practices were approached to participate; 12 pediatric and 123 general practices participated in the study. The overall response rate was 86.5%. MAIN OUTCOME MEASURES: Survey responses and temperature and storage conditions of refrigerators upon inspection. RESULTS: Fewer than seven (6%) practices answered all questions related to vaccine storage and handling correctly, and only 11 (10%) refrigerators had thermometers. One-third of refrigerators had temperatures outside the recommended range of 2 degrees C to 8 degrees C. Older refrigerators were more likely to have inappropriate temperatures than newer ones. CONCLUSIONS: Knowledge and practice of vaccine storage and handling are often inadequate in primary care physicians' offices.
PMCID: PMC2146189  PMID: 7647622
25.  New developments in hepatitis A control. 
Canadian Family Physician  1995;41:1199-1205.
An inactivated vaccine for hepatitis A was recently licensed in Canada. This is the first important development in control of the disease in 50 years. This article presents new information about the vaccine and about the groups who might benefit from it. It also provides a review of the clinical and epidemiological aspects of hepatitis A.
PMCID: PMC2146181  PMID: 7647625

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