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1.  Heterozygous inactivation of Gnas in adipose-derived mesenchymal progenitor cells enhances osteoblast differentiation and promotes heterotopic ossification 
Human genetic disorders sharing the common feature of subcutaneous heterotopic ossification (HO) are caused by heterozygous inactivating mutations in GNAS, a gene encoding multiple transcripts including two stimulatory G-proteins, the α-subunit of the stimulatory G-protein (Gsα) of adenylyl cyclase and the ‘extra-long” form of Gsα, XLαs. In one such disorder, progressive osseous heteroplasia (POH), bone formation initiates within subcutaneous fat before progressing to deeper tissues, suggesting that osteogenesis may involve abnormal differentiation of mesenchymal precursors that are present in adipose tissues. We determined by immunohistochemical analysis that GNAS protein expression is limited to Gsα in bone-lining cells and to Gsα and XLαs in osteocytes. By contrast, the GNAS proteins Gsα, XLαs, and NESP55 are detected in adipocytes and in adipose stroma. Although Gnas transcripts, as assessed by qRT-PCR, show no significant changes upon osteoblast differentiation of bone-derived precursor cells, the abundance of these transcripts is enhanced by osteoblast differentiation of adipose-derived mesenchymal progenitors. Using a mouse knockout model, we determined that heterozygous inactivation of Gnas (by disruption of the Gsα-specific exon 1) abrogates upregulation of multiple Gnas transcripts that normally occurs with osteoblast differentiation in wild-type adipose stromal cells. These transcriptional changes in Gnas+/− mice are accompanied by accelerated osteoblast differentiation of adipose stromal cells in vitro. In vivo, altered osteoblast differentiation in Gnas+/− mice manifests as subcutaneous HO by an intramembranous process. Taken together, these data suggest that Gnas is a key regulator of fate decisions in adipose-derived mesenchymal progenitor cells, specifically those that are involved in bone formation.
doi:10.1002/jbmr.481
PMCID: PMC3584579  PMID: 21812029
GNAS/Gnas; heterotopic ossification; osteoblast differentiation; progressive osseous heteroplasia (POH); Albright hereditary osteodystrophy (AHO); pseudohypoparathyroidism (PHP); osteoma cutis (OC)
2.  A modified Delphi study of screening for fetal alcohol spectrum disorders in Australia 
BMC Pediatrics  2013;13:13.
Background
There is little reliable information on the prevalence of fetal alcohol spectrum disorders (FASD) in Australia and no coordinated national approach to facilitate case detection. The aim of this study was to identify health professionals’ perceptions about screening for FASD in Australia.
Method
A modified Delphi process was used to assess perceptions of the need for, and the process of, screening for FASD in Australia. We recruited a panel of 130 Australian health professionals with experience or expertise in FASD screening or diagnosis. A systematic review of the literature was used to develop Likert statements on screening coverage, components and assessment methods which were administered using an online survey over two survey rounds.
Results
Of the panel members surveyed, 95 (73%) responded to the questions on screening in the first survey round and, of these, 81 (85%) responded to the second round. Following two rounds there was consensus agreement on the need for targeted screening at birth (76%) and in childhood (84%). Participants did not reach consensus agreement on the need for universal screening at birth (55%) or in childhood (40%). Support for targeted screening was linked to perceived constraints on service provision and the need to examine the performance, costs and benefits of screening.
For targeted screening of high risk groups, we found highest agreement for siblings of known cases of FASD (96%) and children of mothers attending alcohol treatment services (93%). Participants agreed that screening for FASD primarily requires assessment of prenatal alcohol exposure at birth (86%) and in childhood (88%), and that a checklist is needed to identify the components of screening and criteria for referral at birth (84%) and in childhood (90%).
Conclusions
There is an agreed need for targeted but not universal screening for FASD in Australia, and sufficient consensus among health professionals to warrant development and evaluation of standardised methods for targeted screening and referral in the Australian context. Participants emphasised the need for locally-appropriate, evidence-based approaches to facilitate case detection, and the importance of ensuring that screening and referral programs are supported by adequate diagnostic and management capacity.
doi:10.1186/1471-2431-13-13
PMCID: PMC3583688  PMID: 23347677
3.  Cranial Nerve Palsies: Sarcoidosis to Systemic Lupus Erythematosus 
Case Reports in Rheumatology  2013;2013:175261.
Cranial palsies are a very rare feature of SLE. Similarly, peripheral sensory-motor axonal neuropathy is very uncommon in SLE. The combination of the two as the presenting symptoms of SLE is a diagnostic challenge particularly in an elderly male patient with a known diagnosis of sarcoidosis. This case serves to highlight the diagnostic considerations in such a patient. The lack of response to standard therapy and the presence of subtle clues like anemia, proteinuria, and mild serositis should prompt the physician to look for alternate diagnoses. The potential association of SLE and sarcoidosis is also discussed. SLE can be present in elderly male patients with cranial and peripheral neuropathy.
doi:10.1155/2013/175261
PMCID: PMC3564269  PMID: 23401835
4.  Postnatally-transmitted HIV-1 Envelope variants have similar neutralization-sensitivity and function to that of nontransmitted breast milk variants 
Retrovirology  2013;10:3.
Background
Breastfeeding is a leading cause of infant HIV-1 infection in the developing world, yet only a minority of infants exposed to HIV-1 via breastfeeding become infected. As a genetic bottleneck severely restricts the number of postnatally-transmitted variants, genetic or phenotypic properties of the virus Envelope (Env) could be important for the establishment of infant infection. We examined the efficiency of virologic functions required for initiation of infection in the gastrointestinal tract and the neutralization sensitivity of HIV-1 Env variants isolated from milk of three postnatally-transmitting mothers (n=13 viruses), five clinically-matched nontransmitting mothers (n=16 viruses), and seven postnatally-infected infants (n = 7 postnatally-transmitted/founder (T/F) viruses).
Results
There was no difference in the efficiency of epithelial cell interactions between Env virus variants from the breast milk of transmitting and nontransmitting mothers. Moreover, there was similar efficiency of DC-mediated trans-infection, CCR5-usage, target cell fusion, and infectivity between HIV-1 Env-pseudoviruses from nontransmitting mothers and postnatal T/F viruses. Milk Env-pseudoviruses were generally sensitive to neutralization by autologous maternal plasma and resistant to breast milk neutralization. Infant T/F Env-pseudoviruses were equally sensitive to neutralization by broadly-neutralizing monoclonal and polyclonal antibodies as compared to nontransmitted breast milk Env variants.
Conclusion
Postnatally-T/F Env variants do not appear to possess a superior ability to interact with and cross a mucosal barrier or an exceptional resistance to neutralization that define their capability to initiate infection across the infant gastrointestinal tract in the setting of preexisting maternal antibodies.
doi:10.1186/1742-4690-10-3
PMCID: PMC3564832  PMID: 23305422
HIV; Mother to child transmission; Galcer; Dendritic cells; Neutralizing antibodies
5.  Consensus diagnostic criteria for fetal alcohol spectrum disorders in Australia: a modified Delphi study 
BMJ Open  2012;2(5):e001918.
Objective
To evaluate health professionals' agreement with components of published diagnostic criteria for fetal alcohol spectrum disorders (FASD) in order to guide the development of standard diagnostic guidelines for Australia.
Design
A modified Delphi process was used to assess agreement among health professionals with expertise or experience in FASD screening or diagnosis. An online survey, which included 36 Likert statements on diagnostic methods, was administered over two survey rounds. For fetal alcohol syndrome (FAS), health professionals were presented with concepts from the Institute of Medicine (IOM), University of Washington (UW), Centers for Disease Control (CDC), revised IOM and Canadian diagnostic criteria. For partial FAS (PFAS), alcohol-related neurodevelopmental disorder (ARND), and alcohol-related birth defects (ARBD), concepts based on the IOM and the Canadian diagnostic criteria were compared.
Setting/participants
130 Australian and 9 international health professionals.
Results
Of 139 health professionals invited to complete the survey, 103 (74.1%) responded, and 74 (53.2%) completed one or more questions on diagnostic criteria. We found consensus agreement among participants on the diagnostic criteria for FAS, with the UW criteria most commonly endorsed when compared with all other published criteria for FAS. When health professionals were presented with concepts based on the Canadian and IOM diagnostic criteria, we found consensus agreement but no clear preference for either the Canadian or IOM criteria for the diagnosis of PFAS, and no consensus agreement on diagnostic criteria for ARND. We also found no consensus on the IOM diagnostic criteria for ARBD.
Conclusions
Participants indicated clear support for use of the UW diagnostic criteria for FAS in Australia. These findings should be used to develop guidelines to facilitate improved awareness of, and address identified gaps in the infrastructure for, FASD diagnosis in Australia.
doi:10.1136/bmjopen-2012-001918
PMCID: PMC3488737  PMID: 23100447
6.  The effect of a cold beverage during an exercise session combining both strength and energy systems development training on core temperature and markers of performance 
Background
Although studies have investigated the effects of hydration on performance measures, few studies have investigated how the temperature of the ingested liquid affects performance and core temperature during an exercise session. The hypothesis of the present study was that cold water would improve thermoregulation and performance as measured by bench repetitions to fatigue, broad jump for force and power and total time to exhaustion for cardiovascular fitness
Methods
Forty-five, physically fit, adult males (30.28 ± 5.4 yr, 1.77 ± 7.8 m, 83.46 ± 11.5 kg; 13.7 ± 4.8 %BF; 49.8 ± 6.3 ml/kg/min V02) completed two 60-minute exercise sessions. Subjects consumed either COLD (4°C) or room temperature (RT) water (22°C) in randomized order. Core temperature was measured every 15 minutes throughout each trial using a digestible thermometer. Three performance tests were performed upon completion of the exercise session: bench press to fatigue, standing broad jump, and bicycle time to exhaustion
Results
Although both groups significantly increased their core temperature (p<0.001) over the course of the exercise session and presented a significant decline in hydration status (p<0.001), participants in the COLD water trial had a significantly (p=0.024) smaller rise in core temperature (0.83°) over the duration of the trial in comparison to RT (1.13°). The participants in the COLD water trial were able to delay their increase in core body temperature for at least 30 minutes, whereas participants in the RT trial increased body temperature from baseline after 15 minutes. There was no significant difference between the COLD or the RT trials in broad jump and TTE performance tests. Bench press showed a small, albeit significant (p=0.046), decrease in performance when drinking COLD
Conclusion
Drinking cold water can significantly mediate and delay the increase in core body temperature during an exercise session in a moderate climate with euhydrated subjects. The ingestion of COLD improved performance for 49% and 51% of the participants in the broad jump and TTE performance tests respectively, but did not reach statistical significance. Moreover, although minimal, subjects experienced a decrease in performance on the bench press during the COLD.
doi:10.1186/1550-2783-9-44
PMCID: PMC3472188  PMID: 22992430
Hydration; Dehydration; Euhydration; Core temperature; Thermoregulation; Performance; Cold water; Exercise
7.  Health professionals’ perceptions about the adoption of existing guidelines for the diagnosis of fetal alcohol spectrum disorders in Australia 
BMC Pediatrics  2012;12:69.
Background
Despite the availability of five guidelines for the diagnosis of fetal alcohol spectrum disorders (FASD), there is no national endorsement for their use in diagnosis in Australia. In this study we aimed to describe health professionals’ perceptions about the adoption of existing guidelines for the diagnosis of FASD in Australia and identify implications for the development of national guidelines.
Methods
We surveyed 130 Australian and 9 international health professionals with expertise or involvement in the screening or diagnosis of FASD. An online questionnaire was used to evaluate participants’ familiarity with and use of five existing diagnostic guidelines for FASD, and to assess their perceptions about the adoption of these guidelines in Australia.
Results
Of the 139 participants surveyed, 84 Australian and 8 international health professionals (66.2%) responded to the questions on existing diagnostic guidelines. Participants most frequently reported using the University of Washington 4-Digit Diagnostic Code (27.2%) and the Canadian guidelines (18.5%) for diagnosis. These two guidelines were also most frequently recommended for adoption in Australia: 32.5% of the 40 participants who were familiar with the University of Washington 4-Digit Diagnostic Code recommended adoption of this guideline in Australia, and 30.8% of the 26 participants who were familiar with the Canadian guidelines recommended adoption of this guideline in Australia. However, for the majority of guidelines examined, most participants were unsure whether they should be adopted in Australia. The adoption of existing guidelines in Australia was perceived to be limited by: their lack of evidence base, including the appropriateness of established reference standards for the Australian population; their complexity; the need for training and support to use the guidelines; and the lack of an interdisciplinary and interagency model to support service delivery in Australia.
Conclusions
Participants indicated some support for the adoption of the University of Washington or Canadian guidelines for FASD diagnosis; however, concerns were raised about the adoption of these diagnostic guidelines in their current form. Australian diagnostic guidelines will require evaluation to establish their validity in the Australian context, and a comprehensive implementation model is needed to facilitate improved diagnostic capacity in Australia.
doi:10.1186/1471-2431-12-69
PMCID: PMC3416706  PMID: 22697051
8.  Pregnancy and Infant Outcomes among HIV-Infected Women Taking Long-Term ART with and without Tenofovir in the DART Trial 
PLoS Medicine  2012;9(5):e1001217.
Diana Gibb and colleagues investigate the effect of in utero tenofovir exposure by analyzing the pregnancy and infant outcomes of HIV-infected women enrolled in the DART trial.
Background
Few data have described long-term outcomes for infants born to HIV-infected African women taking antiretroviral therapy (ART) in pregnancy. This is particularly true for World Health Organization (WHO)–recommended tenofovir-containing first-line regimens, which are increasingly used and known to cause renal and bone toxicities; concerns have been raised about potential toxicity in babies due to in utero tenofovir exposure.
Methods and Findings
Pregnancy outcome and maternal/infant ART were collected in Ugandan/Zimbabwean HIV-infected women initiating ART during The Development of AntiRetroviral Therapy in Africa (DART) trial, which compared routine laboratory monitoring (CD4; toxicity) versus clinically driven monitoring. Women were followed 15 January 2003 to 28 September 2009. Infant feeding, clinical status, and biochemistry/haematology results were collected in a separate infant study. Effect of in utero ART exposure on infant growth was analysed using random effects models.
382 pregnancies occurred in 302/1,867 (16%) women (4.4/100 woman-years [95% CI 4.0–4.9]). 226/390 (58%) outcomes were live-births, 27 (7%) stillbirths (≥22 wk), and 137 (35%) terminations/miscarriages (<22 wk). Of 226 live-births, seven (3%) infants died <2 wk from perinatal causes and there were seven (3%) congenital abnormalities, with no effect of in utero tenofovir exposure (p>0.4). Of 219 surviving infants, 182 (83%) enrolled in the follow-up study; median (interquartile range [IQR]) age at last visit was 25 (12–38) months. From mothers' ART, 62/9/111 infants had no/20%–89%/≥90% in utero tenofovir exposure; most were also zidovudine/lamivudine exposed. All 172 infants tested were HIV-negative (ten untested). Only 73/182(40%) infants were breast-fed for median 94 (IQR 75–212) days. Overall, 14 infants died at median (IQR) age 9 (3–23) months, giving 5% 12-month mortality; six of 14 were HIV-uninfected; eight untested infants died of respiratory infection (three), sepsis (two), burns (one), measles (one), unknown (one). During follow-up, no bone fractures were reported to have occurred; 12/368 creatinines and seven out of 305 phosphates were grade one (16) or two (three) in 14 children with no effect of in utero tenofovir (p>0.1). There was no evidence that in utero tenofovir affected growth after 2 years (p = 0.38). Attained height- and weight for age were similar to general (HIV-uninfected) Ugandan populations. Study limitations included relatively small size and lack of randomisation to maternal ART regimens.
Conclusions
Overall 1-year 5% infant mortality was similar to the 2%–4% post-neonatal mortality observed in this region. No increase in congenital, renal, or growth abnormalities was observed with in utero tenofovir exposure. Although some infants died untested, absence of recorded HIV infection with combination ART in pregnancy is encouraging. Detailed safety of tenofovir for pre-exposure prophylaxis will need confirmation from longer term follow-up of larger numbers of exposed children.
Trial registration
www.controlled-trials.com ISRCTN13968779
Please see later in the article for the Editors' Summary
Editors' Summary
Background
Currently, about 34 million people (mostly in low- and middle-income countries) are infected with HIV, the virus that causes AIDS. At the beginning of the epidemic, more men than women were infected with HIV but now about half of all people living with HIV/AIDS are women, most of who became infected through unprotected sex with an infected partner. In sub-Saharan Africa alone, 12 million women are HIV-positive. Worldwide, HIV/AIDS is the leading cause of death among women of child-bearing age. Moreover, most of the 400,000 children who become infected with HIV every year acquire the virus from their mother during pregnancy or birth, or through breastfeeding, so-called mother-to-child transmission (MTCT). Combination antiretroviral therapy (ART)—treatment with cocktails of powerful antiretroviral drugs—reduces HIV-related illness and death among women, and ART given to HIV-positive mothers during pregnancy and delivery and to their newborn babies greatly reduces MTCT.
Why Was This Study Done?
Because of ongoing international efforts to increase ART coverage, more HIV-positive women in Africa have access to ART now than ever before. However, little is known about pregnancy outcomes among HIV-infected African women taking ART throughout pregnancy for their own health or about the long-term outcomes of their offspring. In particular, few studies have examined the effect of taking tenofovir (an antiretroviral drug that is now recommended as part of first-line ART) throughout pregnancy. Tenofovir readily crosses from mother to child during pregnancy and, in animal experiments, high doses of tenofovir given during pregnancy caused bone demineralization (which weakens bones), kidney problems, and impaired growth among offspring. In this study, the researchers analyze data collected on pregnancy and infant outcomes among Ugandan and Zimbabwean HIV-positive women who took ART throughout pregnancy in the Development of AntiRetroviral Therapy in Africa (DART) trial. This trial was designed to test whether ART could be safely and effectively delivered in Africa without access to the expensive laboratory tests that are routinely used to monitor ART toxicity and efficacy in developed countries.
What Did the Researchers Do and Find?
The pregnancy outcomes of 302 women who became pregnant during the DART trial and information on birth defects among their babies were collected as part of the DART protocol; information on the survival, growth, and development of the infants born to these women was collected in a separate infant study. Most of the women who became pregnant were taking tenofovir-containing ART before and throughout their pregnancies. 58% of the pregnancies resulted in a live birth, 7% resulted in a stillbirth (birth of a dead baby at any time from 22 weeks gestation to the end of pregnancy), and 35% resulted in a termination or miscarriage (before 22 weeks gestation). Of the 226 live births, seven infants died within 2 weeks and seven had birth defects. Similar proportions of the infants exposed and not exposed to tenofovir during pregnancy died soon after birth or had birth defects. Of the 182 surviving infants who were enrolled in the infant study, 14 subsequently died at an average age of 9 months, giving a 1-year mortality of 5%. None of the surviving children who were tested (172 infants) were HIV infected. No bone fractures or major kidney problems occurred during follow-up and prebirth exposure to tenofovir in utero had no effect on growth or weight gain at 2 years (in contrast to a previous US study).
What Do These Findings Mean?
By showing that prebirth tenofovir exposure does not affect pregnancy outcomes or increase birth defects, growth abnormalities, or kidney problems, these findings support the use of tenofovir-containing ART during pregnancy among HIV-positive African women, and suggest that it could also be used to prevent women of child-bearing age acquiring HIV-infection heterosexually. Notably, the observed 5% 1-year infant mortality is similar to the 2%–4% infant mortality normally seen in the region. The absence of HIV infection among the infants born to the DART participants is also encouraging. However, this is a small study (only 111 infants were exposed to tenofovir throughout pregnancy) and women were not randomly assigned to receive tenofovir-containing ART. Consequently, more studies are needed to confirm that tenofovir exposure during pregnancy does not affect pregnancy outcomes or have any long-term effects on infants. Such studies are essential because the use of tenofovir as a treatment for women who are HIV-positive is likely to increase and tenofovir may also be used in the future to prevent HIV acquisition in HIV-uninfected women.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001217.
Information is available from the US National Institute of Allergy and infectious diseases on all aspects of HIV infection and AIDS
NAM/aidsmap provides basic information about HIV/AIDS, and summaries of recent research findings on HIV care and treatment (in several languages)
Information is available from Avert, an international AIDS nonprofit on many aspects of HIV/AIDS, including detailed information on HIV/AIDS treatment and care, women, HIV and AIDS, children, HIV and AIDS, and on HIV/AIDS and pregnancy (some information in English and Spanish); personal stories of women living with HIV are available
More information about the DART trial is available
Additional patient stories about living with HIV/AIDS are available through the nonprofit website Healthtalkonline
doi:10.1371/journal.pmed.1001217
PMCID: PMC3352861  PMID: 22615543
9.  The Genetic Bottleneck in Vertical Transmission of Subtype C HIV-1 Is Not Driven by Selection of Especially Neutralization-Resistant Virus from the Maternal Viral Population ▿ †  
Journal of Virology  2011;85(16):8253-8262.
Subtype C human immunodeficiency virus type 1 (HIV-1C) continues to cause the majority of new cases of mother-to-child transmission (MTCT), and yet there are limited data on HIV-1C transmission. We amplified env from plasma RNA for 19 HIV-1C MTCT pairs, 10 transmitting in utero (IU) and 9 transmitting intrapartum (IP). There was a strong genetic bottleneck between all mother-infant pairs, with a majority of transmission events involving the transmission of a single virus. env genes of viruses transmitted to infants IP, but not IU, encoded Env proteins that were shorter and had fewer putative N-linked glycosylation sites in the V1-V5 region than matched maternal sequences. Viruses pseudotyped with env clones representative of each maternal and infant population were tested for neutralization sensitivity. The 50% inhibitory concentration of autologous serum was similar against both transmitted (infant) and nontransmitted (maternal) viruses in a paired analysis. Mother and infant Env proteins were also similar in sensitivity to soluble CD4, to a panel of monoclonal antibodies, and to heterologous HIV-1C sera. In addition, there was no difference in the breadth or potency of neutralizing antibodies between sera from 50 nontransmitting and 23 IU and 23 IP transmitting HIV-1C-infected women against four Env proteins from heterologous viruses. Thus, while a strong genetic bottleneck was detected during MCTC, with viruses of shorter and fewer glycosylation sites in env present in IP transmission, our data do not support this bottleneck being driven by selective resistance to antibodies.
doi:10.1128/JVI.00197-11
PMCID: PMC3147968  PMID: 21593171
10.  Low haemoglobin predicts early mortality among adults starting antiretroviral therapy in an HIV care programme in South Africa: a cohort study 
BMC Public Health  2010;10:433.
Background
Antiretroviral therapy (ART) has dramatically reduced morbidity and mortality among people with HIV infection; however, mortality after the start of ART is high in resource-limited settings. We investigated risk factors for mortality among adults starting ART in a multi-clinic community programme in South Africa.
Methods
Cohort of adults starting ART at 27 clinics between February 2005 and June 2006, followed to 31st March 2007. Kaplan-Meier survival estimates were used to describe overall mortality. Shared frailty Cox regression was used to identify baseline risk factors for early mortality.
Results
Among 1350 participants (median age 35.5 years, 60% female, median CD4 count 83/μL [interquartile range (27 - 147)], median follow-up 13.4 months), there were 185 deaths, overall mortality rate 13/100 pyrs; for 0-3, 3-9 and >9 months from ART start mortality rates were 24, 13 and 6/100 pyrs respectively. 43% of the deaths were in the first 3 months of treatment. Risk factors for mortality in univariable analysis were baseline CD4 count, viral load, haemoglobin and body mass index, in multivariable analysis adjusting for age and gender, only CD4 count and haemoglobin remained independently associated with proportional hazards not being satisfied for haemoglobin. Adjusted hazard ratios (aHR) for participants with haemoglobin <8, 8.1-9.9, >11.9(f)/12.9 (m) g/mL were 4.99, 3.05 and 0.12 respectively comparing to 10-11.9 (f)/12.9 (m)g/mL in the first 3 months of ART. aHRs for CD4 counts were 0.40, 0.38 and 0.34 for 50-99, 100-200 and >200/μL comparing to <50/μL.
Conclusions
The high mortality rate in the first 3 months underlines the need for earlier HIV diagnosis so that ART can be initiated earlier. Low haemoglobin and low CD4 count are both strong predictors of mortality, and could be used to identify individuals at high risk who might benefit from intensive case management.
doi:10.1186/1471-2458-10-433
PMCID: PMC2919476  PMID: 20653940
11.  The Molecular Epidemiology of HIV-1 Envelope Diversity During HIV-1 Subtype C Vertical Transmission in Malawian Mother-Infant Pairs 
AIDS (London, England)  2008;22(7):863-871.
OBJECTIVE
To study the relationship between HIV-1 subtype C genetic diversity and mother-to-child transmission and to determine if transmission of HIV-1C V1/V2 env variants occurs stochastically.
DESIGN
Case-case-control study of Malawian mother-infant pairs consisting of 32 non-transmitting women, 25 intrauterine (IU) transmitters and 23 intrapartum (IP) transmitters in Blantyre, Malawi.
METHODS
A heteroduplex tracking assay against the highly variable HIV env V1/V2 region was used to characterize the relationship between HIV diversity and HIV-1 MTCT. The relative abundance of the maternal env variants was quantified, and based on the env variants detected in the infant plasma, categorized as transmitted or untransmitted. The V1/V2 region was sequenced from two mother-infant pairs and a phylogenetic tree was built.
RESULTS
No relationship was found between transmission and overall maternal env diversity. Infants had less diverse HIV-1 populations than their mothers, and IU-infected infants had fewer V1/V2 variants and were more likely to harbor a homogeneous V1/V2 population than infants infected IP. V1/V2 sequences cloned from two mother-infant transmission pairs support multiple env variant transmission when multiple variants are detected, rather than single variant transmission followed by diversification. Almost 50% of the HIV-infected infants contained V1/V2 env variants that were not detected in maternal plasma samples, and, transmission of env variants was not related to their abundance in maternal blood.
CONCLUSIONS
These data suggest that the predominant mechanism(s) of HIV-1 subtype C MTCT differs by the timing of transmission and is unlikely to be explained by a simple stochastic model.
doi:10.1097/QAD.0b013e3282f51ea0
PMCID: PMC2760232  PMID: 18427205
15.  New Method for Antibiotic Susceptibility Testing 
The most widely used method for routine antibiotic susceptibility testing of clinical isolates of bacteria is the paper-disc method. This has the advantage of simplicity, but to obtain reliable results considerable care is required both in the standardization of the procedure and in the interpretation of the zones of inhibition. A new susceptibility test method is described in this report which retains the simplicity of the paper-disc method but which enables organisms to be tested directly for susceptibility to known concentrations of antibiotic in agar. Organisms may be tested against a single concentration of antibiotic or, alternatively, a range of concentrations may be used to determine the minimal inhibitory concentration. The method utilizes stable pre-prepared materials and is not appreciably more time consuming than the conventional disc method.
Images
PMCID: PMC444266  PMID: 4670487

Results 1-16 (16)