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1.  Cystine nephrolithiasis 
Our understanding of the molecular basis of cystinuria has deepened as the result of the causative genes, SLC3A1 and SLC7A9, being identified. The proteins coded for by these genes form a heterodimer responsible for reabsorption of filtered cystine in the proximal tubule. Failure of this transport system to be targeted to the apical membrane, as in the case of SLC3A1 mutations, or failure of the transport system to function, as in the case of SLC7A9 mutations, leads to abnormal urinary excretion of the relatively insoluble amino acid cystine. Stones and plugs of tubules result, with chronic kidney disease a frequent complication. Here we review the genetics, pathophysiology, pathology, clinical manifestations and clinical management. Increased fluid intake, restriction of sodium and animal protein ingestion, and urinary alkalinization are the standard therapies. Cystine binding thiol drugs tiopronin and D-penicillamine are reserved for patients for whom the conservative therapies are insufficient. New studies of cystine crystal inhibition are highlighted.
PMCID: PMC4220544  PMID: 25383320
Cystinuria; D-penicillamine; kidney stones; tiopronin; urolithiasis
2.  Hereditary Causes of Kidney Stones and Chronic Kidney Disease 
Pediatric nephrology (Berlin, Germany)  2013;28(10):1923-1942.
Adenine phosphoribosyltransferase (APRT) deficiency, cystinuria, Dent disease, familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) and primary hyperoxaluria (PH) are rare but important causes of severe kidney stone disease and/or chronic kidney disease in children. Recurrent kidney stone disease and nephrocalcinosis, particularly in pre-pubertal children, should alert the physician to the possibility of an inborn error of metabolism as the underlying cause. Unfortunately, the lack of recognition and knowledge of the five disorders has frequently resulted in an unacceptable delay in diagnosis and treatment, sometimes with grave consequences. A high index of suspicion coupled with early diagnosis may reduce or even prevent the serious long-term complications of these diseases. In this paper, we review the epidemiology, clinical features, diagnosis, treatment and outcome of patients with APRT deficiency, cystinuria, Dent disease, FHHNC and PH with emphasis on childhood manifestations.
PMCID: PMC4138059  PMID: 23334384
Nephrolithiasis; nephrocalcinosis; kidney failure; crystalline nephropathy; hereditary disorders; adenine phosphoribosyltransferase deficiency; 2,8-dihydroxyadeninuria; cystinuria; Dent disease; familial hypomagnesemia with hypercalciuria and nephrocalcinosis; primary hyperoxaluria
3.  Metabolic Evaluation of First-time and Recurrent Stone Formers 
PMCID: PMC4052537  PMID: 23177631
Diagnosis; Calcium oxalate; Humans; Kidney calculi/urine; Nephrolithiasis; Uric acid; Urolithiasis
4.  Hospital-based Surveillance for Rotavirus Gastroenteritis using Molecular Testing and Immunoassay during the 2011 Season in Botswana 
The Pediatric infectious disease journal  2013;32(5):10.1097/INF.0b013e3182847295.
We describe rotavirus testing results, demographics, seasonality and outcomes in children admitted with acute gastroenteritis to hospital during Botswana’s 2011 rotavirus season.
Rotavirus season extended from mid-June until the end of October with the rotavirus-specific case-fatality being 2.8%. Using PCR as the reference, the immunochromatographic test had a sensitivity of 76.5% and specificity of 68.0%. Rotavirus vaccine may significantly reduce childhood morbidity and mortality in Botswana.
PMCID: PMC3874800  PMID: 23340563
Rotavirus; Botswana; diarrhea; PCR; immunoassay
5.  Facilitating the transition from physiology to hospital wards through an interdisciplinary case study of septic shock 
BMC Medical Education  2014;14:78.
In order to develop clinical reasoning, medical students must be able to integrate knowledge across traditional subject boundaries and multiple disciplines. At least two dimensions of integration have been identified: horizontal integration, bringing together different disciplines in considering a topic; and vertical integration, bridging basic science and clinical practice. Much attention has been focused on curriculum overhauls, but our approach is to facilitate horizontal and vertical integration on a smaller scale through an interdisciplinary case study discussion and then to assess its utility.
An interdisciplinary case study discussion about a critically ill patient was implemented at the end of an organ system-based, basic sciences module at New York University School of Medicine. Three clinical specialists—a cardiologist, a pulmonologist, and a nephrologist—jointly led a discussion about a complex patient in the intensive care unit with multiple medical problems secondary to septic shock. The discussion emphasized the physiologic underpinnings behind the patient’s presentation and the physiologic considerations across the various systems in determining proper treatment. The discussion also highlighted the interdependence between the cardiovascular, respiratory, and renal systems, which were initially presented in separate units. After the session students were given a brief, anonymous three-question free-response questionnaire in which they were asked to evaluate and freely comment on the exercise.
Students not only took away physiological principles but also gained an appreciation for various thematic lessons for bringing basic science to the bedside, especially horizontal and vertical integration. The response of the participants was overwhelmingly positive with many indicating that the exercise integrated the material across organ systems, and strengthened their appreciation of the role of physiology in understanding disease presentations and guiding appropriate therapy.
Horizontal and vertical integration can be presented effectively through a single-session case study, with complex patient cases involving multiple organ systems providing students opportunities to integrate their knowledge across organ systems while emphasizing the importance of physiology in clinical reasoning. Furthermore, having several clinicians from different specialties discuss the case together can reinforce the matter of integration across multiple organ systems and disciplines in students’ minds.
PMCID: PMC3991870  PMID: 24725336
Integrated curriculum; Problem-based learning; Undergraduate medical education; Physiology
7.  Symptomatic Central Venous Stenosis in a Hemodialysis Patient Leading to Loss of Arteriovenous Access: A Case Report and Literature Review 
Nephron Extra  2014;4(1):50-54.
Central venous stenosis is a well-described sequel to the placement of hemodialysis catheters in the central venous system. The presence of an ipsilateral arteriovenous fistula or graft often leads to severe venous dilatation, arm edema and recurrent infections. Vascular access thrombosis, compromised blood flow and inadequate dialysis delivery are dreaded complications that eventually render the access unusable. We report the case of a 58-year-old male hemodialysis patient who developed symptomatic central venous stenosis to illustrate the problem and review the pertinent literature. This patient developed severe enlargement of upper extremity veins due to central venous stenosis. The symptoms were refractory to multiple endovascular interventions and eventually necessitated ligation of his arteriovenous fistula. Central venous stenosis remains a pervasive problem despite advances in our understanding of its etiology and recognition of the enormity of its consequences. Due to the lack of effective therapeutic options, prevention is better than cure.
PMCID: PMC3999441  PMID: 24803921
Central venous stenosis; Hemodialysis; Arteriovenous access

8.  Diet, but not oral probiotics, effectively reduces urinary oxalate excretion and calciumoxalate supersaturation 
Kidney international  2010;78(11):1178-1185.
We examined the effect of a controlled diet and two probiotic preparations on urinary oxalate excretion, a risk factor for calcium oxalate kidney stone formation, in patients with mild hyperoxaluria. Patients were randomized to a placebo, a probiotic, or a synbiotic preparation. This tested whether these probiotic preparations can increase oxalate metabolism in the intestine and/or decrease oxalate absorption from the gut. Patients were maintained on a controlled diet to remove the confounding variable of differing oxalate intake from food. Urinary oxalate excretion and calcium oxalate supersaturation on the controlled diet were significantly lower compared with baseline on a free-choice diet. Neither study preparation reduced urinary oxalate excretion nor calcium oxalate supersaturation. Fecal lactobacilli colony counts increased on both preparations, whereas enterococcal and yeast colony counts were increased on the synbiotic. Total urine volume and the excretion of oxalate and calcium were all strong independent determinants of urinary calcium oxalate supersaturation. Hence, dietary oxalate restriction reduced urinary oxalate excretion, but the tested probiotics did not influence urinary oxalate levels in patients on a restricted oxalate diet. However, this study suggests that dietary oxalate restriction is useful for kidney stone prevention.
PMCID: PMC3923490  PMID: 20736987
diet therapy; lactobacilli; nephrolithiasis; probiotic; synbiotic; urolithiasis
9.  The Association of Community Health Indicators With Outcomes for Kidney Transplant Recipients in the United States 
To evaluate the association of community health indicators with outcomes for kidney transplant recipients.
Retrospective observational cohort study using multivariable Cox proportional hazards models.
Transplant recipients in the United States from the Scientific Registry of Transplant Recipients merged with health indicators compiled from several national databases and the Centers for Disease Control and Prevention, including the National Center for Health Statistics, the Behavioral Risk Factor Surveillance System, and the National Center for Chronic Disease Prevention and Health Promotion.
A total of 100 164 living and deceased donor adult (aged ≥18 years) kidney transplant recipients who underwent a transplant between January 1, 2004, and December 31, 2010.
Main Outcome Measures
Risk-adjusted time to post-transplant mortality and graft loss.
Multiple health indicators from recipients’ residence were independently associated with outcomes, in cluding low birth weight, preventable hospitalizations, inactivity rate, and smoking and obesity prevalence. Recipients in the highest-risk counties were more likely to be African American (adjusted odds ratio, 1.59, 95% CI, 1.51-1.68), to be younger (aged 18-39 years; 1.46; 1.32-1.60), to have lower educational attainment (
In a national cohort of patients undergoing complex medical procedures, health indicators from patients’ communities are strong independent predictors of all-cause mortality. Findings highlight the importance of community conditions for risk stratification of patients and development of individualized treatment protocols. Findings also demonstrate that standard risk adjustment does not capture important factors that may affect unbiased performance evaluations of transplant centers.
PMCID: PMC3880685  PMID: 22351876
Rare Tumors  2013;5(4):e57.
Tubulocystic renal cell carcinoma (TC-RCC) is a rare renal tumor composed of well-differentiated tubules and cysts lined by neoplastic cells with eosinophilic cytoplasm and prominent nucleoli. The origin of the tumor cells is still controversial. TC-RCC typically arises unilaterally. Involvement of both kidneys by multifocal TC-RCC has not been reported. In this study we report the first case of bilateral and multifocal TC-RCC. Immunohistochemical, cytogenetic and ultrastructural studies suggest TC-RCC is closely related to papillary RCC.
PMCID: PMC3882929  PMID: 24416491
renal cell carcinoma; tubulocystic carcinoma; cytogenetics; immunohistochemistry
BMC Pediatrics  2013;13:142.
Cytomegalovirus is the most common pathogen causing congenital infection and can result in significant neurodevelopmental adverse outcomes. For this reason, it is the standard of care in many regions to treat congenital cytomegalovirus infection involving the brain with six weeks of ganciclovir. There have been no reports in the published literature of significant cytomegalovirus neonatal infection in infants previously treated for congenital infection.
Case presentation
A preterm male infant with congenital symptomatic cytomegalovirus infection was initially treated with over 8 weeks of ganciclovir between the ages of 3 and 14 weeks. At four months chronologic age, just prior to planned discharge, he developed an episode of life-threatening multisystem cytomegalovirus disease notable for severe pneumonitis, encephalitis, hepatitis, and disseminated intravascular coagulation. This disease resolved after re-treatment with a prolonged course of intravenous ganciclovir and oral valganciclovir.
Clinicians should be aware of the possibility of recurrence of congenital cytomegalovirus infection, especially in preterm infants. Serial plasma cytomegalovirus viral load monitoring may have a role in the management of premature infants treated with ganciclovir; had the diagnosis of recrudescent cytomegalovirus infection been considered sooner, specific therapy might have been more quickly initiated and perhaps further morbidity would have been prevented.
PMCID: PMC3847698  PMID: 24024982
Cytomegalovirus; Congenital infection; Ganciclovir
Case reports in nephrology  2013;2013:268401.
Introduction. Minimal Change Disease (MCD) is the most common cause of nephrotic syndrome in children, while IgA nephropathy is the most common cause of glomerulonephritis worldwide. MCD is responsive to glucocorticoids, while the role of steroids in IgA nephropathy remains unclear. We describe a case of two distinct clinical and pathological findings, raising the question of whether MCD and IgA nephropathy are separate entities or if there is a common pathophysiology. Case Report. A 19-year old man with no medical history presented to the Emergency Department with a 20-day history of anasarca and frothy urine, BUN 68 mg/dL, Cr 2.3 mg/dL, urinalysis 3+ RBCs, 3+ protein, and urine protein : creatinine ratio 6.4. Renal biopsy revealed hypertrophic podocytes on light microscopy, podocyte foot process effacement on electron microscopy, and immunofluorescent mesangial staining for IgA. The patient was started on prednisone and exhibited dramatic improvement. Discussion. MCD typically has an overwhelming improvement with glucocorticoids, while the resolution of IgA nephropathy is rare. Our patient presented with MCD with the uncharacteristic finding of hematuria. Given the improvement with glucocorticoids, we raise the question of whether there is a shared pathophysiologic component of these two distinct clinical diseases that represents a clinical variant.
PMCID: PMC3914242  PMID: 24527245
PLoS ONE  2013;8(4):e60380.
Background and Objectives
Sodium thiosulfate (STS) reduced calcium stone formation in both humans and genetic hypercalciuric stone forming (GHS) rats. We sought to measure urine chemistry changes resulting from STS administration in people.
Design, Setting, Participants & Measurements
STS was given to healthy and hypercalciuric stone forming adults. Five normal non-stone forming adults (mean age 33 years), and 5 people with idiopathic hypercalciuria and calcium kidney stones (mean age 66 years) participated. Two baseline 24-hour urine collections were performed on days 2 and 3 of 3 days of self-selected diets. Subjects then drank STS 10 mmol twice a day for 7 days and did urine collections while repeating the self-selected diet. Results were compared by non-parametric Wilcoxon signed rank test. The primary outcome was the resulting change in urine chemistry.
STS administration did not cause a significant change in urinary calcium excretion in either group. In both groups, 24 hour urinary ammonium (P = 0.005) and sulfate excretion (P = 0.007) increased, and urinary pH fell (P = 0.005); citrate excretion fell (P<0.05) in hypercalciuric participants but not in non-stone formers. Among stone formers with hypercalciuria, 3 of 5 patients had measurement of serum HCO3 concentration after the STS period: it did not change. The net effect was an increase in supersaturation of uric acid, and no change in supersaturation of calcium oxalate or calcium phosphate.
The basis for studies demonstrating that STS prevented stones in rats and people was not reflected by the changes in urine chemistry reported here. Although serum HCO3 did not change, urine tests suggested an acid load in both non-stone forming and hypercalciuric stone-forming participants. The long term safety of STS needs to be determined before the drug can be tested in humans for long-term prevention of stone recurrence.
PMCID: PMC3620159  PMID: 23593205
PLoS ONE  2013;8(3):e57776.
The microbiology and epidemiology of UTI pathogens are largely unknown in Botswana, a high prevalence HIV setting. Using laboratory data from the largest referral hospital and a private hospital, we describe the major pathogens causing UTI and their antimicrobial resistance patterns.
This retrospective study examined antimicrobial susceptibility data for urine samples collected at Princess Marina Hospital (PMH), Bokamoso Private Hospital (BPH), or one of their affiliated outpatient clinics. A urine sample was included in our dataset if it demonstrated pure growth of a single organism and accompanying antimicrobial susceptibility and subject demographic data were available.
A total of 744 samples were included. Greater than 10% resistance was observed for amoxicillin, co-trimoxazole, amoxicillin-clavulanate, and ciprofloxacin. Resistance of E. coli isolates to ampicillin and co-trimoxazole was greater than 60% in all settings. HIV status did not significantly impact the microbiology of UTIs, but did impact antimicrobial resistance to co-trimoxazole.
Data suggests that antimicrobial resistance has already emerged to most oral antibiotics, making empiric management of outpatient UTIs challenging. Ampicillin, co-trimoxazole, and ciprofloxacin should not be used as empiric treatment for UTI in this context. Nitrofurantoin could be used for simple cystitis; aminoglycosides for uncomplicated UTI in inpatients.
PMCID: PMC3587627  PMID: 23469239
International Journal of Circumpolar Health  2013;72:10.3402/ijch.v72i0.19903.
Little is known about the microbiology of diarrhoeal disease in Canada's Arctic regions. There are a number of limitations of conventional microbiology testing techniques for diarrhoeal pathogens, and these may be further compromised in the Arctic, given the often long distances for specimen transport.
To develop a novel multiple-target nanolitre real-time reverse transcriptase (RT)-PCR platform to simultaneously test diarrhoeal specimens collected from residents of the Qikiqtani (Baffin Island) Region of Nunavut, Canada, for a wide range of bacterial, parasitic and viral agents.
Study design/methods
Diarrhoeal stool samples submitted for bacterial culture to Qikiqtani General Hospital in Nunavut over an 18-month period were tested with a multiple-target nanolitre real-time PCR panel for major diarrhoeal pathogens including 8 bacterial, 6 viral and 2 parasitic targets.
Among 86 stool specimens tested by PCR, a total of 50 pathogens were detected with 1 or more pathogens found in 40 (46.5%) stool specimens. The organisms detected comprised 17 Cryptosporidium spp., 5 Clostridium difficile with toxin B, 6 Campylobacter spp., 6 Salmonella spp., 4 astroviruses, 3 noroviruses, 1 rotavirus, 1 Shigella spp. and 1 Giardia spp. The frequency of detection by PCR and bacterial culture was similar for Salmonella spp., but discrepant for Campylobacter spp., as Campylobacter was detected by culture from only 1/86 specimens. Similarly, Cryptosporidium spp. was detected in multiple samples by PCR but was not detected by microscopy or enzyme immunoassay.
Cryptosporidium spp., Campylobacter spp. and Clostridium difficile may be relatively common but possibly under-recognised pathogens in this region. Further study is needed to determine the regional epidemiology and clinical significance of these organisms. This method appears to be a useful tool for gastrointestinal pathogen research and may also be helpful for clinical diagnostics and outbreak investigation in remote regions where the yield of routine testing may be compromised.
PMCID: PMC3619031  PMID: 23570023
multiplex real-time PCR; detection; pathogens; Campylobacter spp.; Cryptosporidium spp.; Clostridium difficile; viral agents; diarrhoea; gastroenteritis; Nunavut; Arctic
Journal of Endourology  2011;25(11):1781-1785.
Background and Purpose
Oxalobacter formigenes (OF) may play a protective role in preventing calcium oxalate stones. This is the first prospective study to evaluate the effect of antibiotics on OF colonization. Intestinal colonization by OF is associated with reduced urinary oxalate excretion. Exposure to antibiotics may be an important factor determining rates of colonization.
Materials and Methods
The effect of antibiotics on OF colonization was compared in two groups: A group receiving antibiotics for gastric infection with Helicobacter pylori (HP) and a group without HP whose members were not receiving antibiotics. OF colonization in stool was detected by oxalate degradation at baseline and after 1 and 6 months.
The prevalence at baseline of intestinal colonization with OF was 43.1% among all patients screened. Among the 12 patients who were positive for OF who did not receive antibiotics, 11 (92%) had OF on stool tests at 1 month and 6 months. Of the 19 participants who were positive for OF and who received antibiotics for HP, only 7 (36.8%) continued to be colonized by OF on follow-up stool testing at 1 and 6 months (P=0.003 by Fisher exact test). Amoxicillin and clarithromycin caused 62.5% of subjects to become negative for OF at 1 month; 56.2% remained negative for OF at 6 months.
Antibiotics for HP infection effectively reduced colonization with OF, an effect present at 1 and 6 months after treatment. The lasting elimination of OF could be associated with hyperoxaluria and be a factor in recurrent kidney stone disease.
PMCID: PMC3210432  PMID: 22017284
Nephron Extra  2011;1(1):212-216.
Patients treated with erythropoiesis-stimulating agents (ESAs) to a hemoglobin (Hb) level >12.0 g/dl have increased risk of multiple complications, including death. The optimal Hb target for ESA use has not been established. We hypothesized that reducing the target Hb would prevent levels >12 g/dl and lead to significant cost savings.
Our target Hb range was reduced to 9–11 g/dl from 10–12 g/dl. Thirty-five chronic hemodialysis (HD) patients received erythropoietin (EPO) and intravenous iron from January to December 2009. Data analysis included: Hb level, EPO dose, transferrin saturation and ferritin levels. EPO was administered via subcutaneous injection weekly or twice weekly.
The mean monthly Hb level changed from 11.2 to 10.6 g/dl. The percentages of patients with mean Hb >10.0, 12.0 and 13.0 g/dl were 82 ± 6.5, 10 ± 5.6 and 1.8 ± 1.9%, respectively. Weekly EPO dose decreased from 9,500 to 5,600 units, a 40% reduction per dose per patient and costs. The savings exceeded USD 60,000 per year for 35 patients. More than 80% of patients had transferrin saturation >20% and ferritin >200 ng/ml throughout the entire period.
Lowering the target Hb range to 9–11 g/dl in HD patients achieved quality anemia management, avoided values >12.0 g/dl and resulted in cost savings. A minimal reduction in quality of life and no change in cardiovascular morbidity or mortality would be expected. The study has important implications in the new American bundled reimbursement model.
PMCID: PMC3290836  PMID: 22470394
Anemia; Chronic kidney disease; Erythropoietin; Hemodialysis; Iron; Kidney failure
Rapid diagnosis of GAS pharyngitis may improve patient care by ensuring that patients with GAS pharyngitis are treated quickly and also avoiding unnecessary use of antibiotics in those without GAS infection. Very few molecular methods for detection of GAS in clinical throat swab specimens have been described.
We performed a study of a laboratory-developed internally-controlled rapid Group A streptococcus (GAS) PCR assay using flocked swab throat specimens. We compared the GAS PCR assay to GAS culture results using a collection of archived throat swab samples obtained during a study comparing the performance of conventional and flocked throat swabs.
The sensitivity of the GAS PCR assay as compared to the reference standard was 96.0% (95% CI 90.1% to 98.4%), specificity 98.6% (95% CI 95.8% to 99.5%), positive predictive value (PPV) 96.9% (95% CI 91.4% to 99.0%) and negative predictive value (NPV) of 98.1% (95% CI 95.2% to 99.2%). For conventional swab cultures, sensitivity was 96.0% (95% CI 90.1% to 98.4%), specificity 100% (95% CI 98.2% to 100%), PPV 100%, (95% CI 96.1% to 100%) and NPV 98.1% (95% CI 95.2% to 99.3%)
In this retrospective study, the GAS PCR assay appeared to perform as well as conventional throat swab culture, the current standard of practice. Since the GAS PCR assay, including DNA extraction, can be performed in approximately 1 hour, prospective studies of this assay are warranted to evaluate the clinical impact of the assay on management of patients with pharyngitis.
PMCID: PMC3179694  PMID: 21888649
PCR; rapid; internally-controlled; LCGreen; Group A Streptococcus; pharyngitis; flocked swab
PMCID: PMC2911451  PMID: 20659621
Individuals with advanced chronic kidney disease (CKD) and end stage renal disease (ESRD) have high total plasma homocysteine (tHcy) levels, which may be a risk factor for cognitive impairment. Whether treatment with high dose B-vitamins to reduce high tHcy levels improves cognition in persons with kidney disease is unknown.
Study Design
Randomized controlled trial.
Setting & Participants
A substudy of 659 patients (mean age 67.3 ± 11.7 years) who participated in a randomized, double-blind, clinical trial, 5 years in duration, conducted in 36 US Department of Veterans Affairs medical centers, of the effect on all-cause mortality of vitamin-induced lowering of plasma tHcy. 236 (35.8%) were treated by dialysis (ESRD) and 423 (64.2%) had a Cockcroft-Gault estimated creatinine clearance ≤ 30 ml/min (advanced CKD). All had high tHcy levels (≥15 μmol/L) at baseline. Cognitive assessments began during the follow up period of the main trial, 3 years after treatment began; participants were subsequently retested one year later to assess cognitive change.
Daily high dose B-vitamin capsule (40 mg of folic acid, 100 mg of vitamin B6, and 2 mg of vitamin B12) or placebo.
Cognitive function at initial assessment and one year later.
The Telephone Interview of Cognitive Status – modified, supplemented with attention, working memory and executive function tests.
Initial cognitive function was impaired in approximately 19% of patients, regardless of treatment assignment (vitamin or placebo) or kidney disease status (advanced CKD or ESRD). Treatment reduced tHcy levels by 26.7%. Unadjusted and adjusted analyses showed that treatment did not improve initial cognitive outcomes or affect subsequent cognitive status one year later.
Cognitive assessments began after treatment was initiated; cognitive assessment was limited.
Treatment with high daily doses of B-vitamins, which reduced tHcy levels, did not affect cognitive outcomes in patients with advanced CKD and ESRD.
PMCID: PMC2748786  PMID: 19628319
Cognition; Kidney Disease; Homocysteine; Clinical Trial
Traffic (Copenhagen, Denmark)  2008;9(10):1653-1664.
The endoplasmic reticulum (ER) in S. cerevisae is largely divided between perinuclear and cortical compartments. Yeast Nvj1 localizes exclusively to small patches on the perinuclear ER, where it interacts with Vac8 in the vacuole membrane to form nucleus-vacuole (NV) junctions. Three regions of Nvj1 mediate the biogenesis of NV junctions. A membrane-spanning domain targets the protein to the ER. The C-terminus binds Vac8 in the vacuole membrane, which induces the clustering of both proteins into NV junctions. The luminal N-terminus is required for strict perinuclear localization. 3D cryo-electron tomography reveals that Nvj1 clamps the separation between the two nuclear membranes to half the width of bulk nuclear envelope. The N-terminus contains a hydrophobic sequence bracketed by basic residues that resembles outer mitochondrial membrane signal-anchors. The hydrophobic sequence can be scrambled or reversed without affecting function. Mutations that reduce the hydrophobicity of the core sequence, or affect the distribution of basic residues, cause mislocalization to the cortical ER. We conclude that the N-terminus of Nvj1 is a retention sequence that bridges the perinuclear lumen and inserts into the inner nuclear membrane.
PMCID: PMC2922689  PMID: 18694438
Journal of Clinical Microbiology  2009;47(9):3029-3030.
We compared the performance of flocked swabs to that of traditional swabs for culture of beta-hemolytic streptococci in children with pharyngitis. Sensitivity was higher for flocked swabs, but this did not reach statistical significance. We conclude that flocked swabs can be used in place of traditional swabs for diagnosis of streptococcal pharyngitis.
PMCID: PMC2738109  PMID: 19605581
Gout recently passed rheumatoid arthritis to become the most common inflammatory arthritis in the United States (US). However, epidemiologic studies indicate that the quality of gout management is suboptimal owing to both patient and physician issues. Only three options for urate-lowering therapy are currently available in the US: allopurinol, probenecid, and recently, febuxostat. Probenecid is generally safe except for the occurrence of urolithiasis, but is only effective for the subset of patients with better kidney function. Allopurinol use is limited due to its side effects, potential toxicity of uncertain magnitude in patients with renal disease, and failure to achieve targeted serum urate levels. In part this failure may be due to the necessity for it to be titrated for optimal therapeutic effect. Febuxostat is a new medication that may offer several advantages and can be given as an alternative to allopurinol. We review the basic biology and clinical performance of febuxostat, and consider the potential utility of this agent in comparison to the older, better-established gout therapeutics.
PMCID: PMC3108781  PMID: 21694922
allopurinol; gout suppressants; nephrolithiasis; uric acid; urolithiasis
Journal of Clinical Microbiology  2009;47(6):1920-1922.
Klebsiella pneumoniae isolates from three patients admitted to the Ottawa Hospital, a 1,040-bed teaching hospital, were found to contain the plasmid-borne K. pneumoniae carbapenemase (KPC)-producing bla gene (blaKPC). There was evidence of person-to-person transmission for two patients. Screening of 186 clinical isolates revealed no additional blaKPC-containing isolates.
PMCID: PMC2691101  PMID: 19357206

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