Comparison of growth rates of bovine retinal and brain microvascular pericytes in different oxygen concentrations in vitro

Background: The hyperoxic injury of the microcirculation in the central nervous system appears to be specific to the retina in premature mammals. Oxygen tensions in normal adult mammalian retina and brain vary between nearly 0 and 90 mmHg. This study sought to compare the in vitro replication of retinal and brain microvascular pericytes in normal glucose medium and in 1 %, 5% and 20% oxygen (equivalent to 15 mmHg, 35 mmHg and 150 mmHg, respectively).
Methods: A preliminary study, using oxygen micro-electrodes, confirmed that the pericellular oxygen tension of pericytes, cultured in medium under air, was within 13 mmHg of the tension of the gas phase above the media.
Pericytes were highly enriched by magnetic antibody cell sorting with the anti-pericyte monoclonal antibody (3G5) to 95% to 99% purity, to remove cell contaminants which may have invalidated the mitogenic assay.
Results: Mitogenic assays showed that brain pericytes replicated faster than their counterparts from retina (f< 0.0001, averaged for data from all culture conditions using three-way ANOVA). Reduction of oxygen tension from 150 to 15 mmHg led to significantly increased replication of retinal pericytes ( P =0.01), but an insignificant increase for brain pericytes.
Conclusions: We have found that pericytes from the brain and retina cultured conventionally in fetal calf serum consume a relatively low amount of oxygen. Decreasing the oxygen tension to 1% (15 to 20 mmHg) increased the replication of retinal pericytes but not brain pericytes in normal glucose concentrations and in fetal calf serum. That retinal pericyte replication is sensitive to variation in oxygen tensions, indicates that the retinal microvascular cells have a unique biological response. This growth sensitivity to oxygen may be important in the pathogenesis of retinopathy of prematurity.     

DNA analysis of HLA-DR, DQ, and DP alleles in children with polyarticular juvenile rheumatoid arthritis.

HLA-DR, DQ and DP alleles were determined by restriction fragment length polymorphism analysis and oligonucleotide probe hybridization of polymerase chain reaction amplified genomic DNA in 94 Caucasian children with polyarticular juvenile rheumatoid arthritis (JRA) [13 rheumatoid factor (RF)+ and 81 RF-] and 100 healthy controls. HLA-DRw8, DQw4, DQA1*0401, DQB1*0402 were increased in frequency in those patients with RF seronegative disease, with highest frequencies seen in patients with young age at onset (< 5 years of age). These findings were similar to what we observed in children with pauciarticular JRA, especially those with young age at onset. DPB1*0301 was also found in increased frequency in the RF- group, and in particular those seronegative for antinuclear antibody. In contrast to what is observed in patients with pauciarticular JRA, the frequency of DPB1*0201 was not increased in any polyarticular JRA patient group. These data suggest that polyarticular JRA shares many genetic features with pauciarticular JRA.     

Pharmacokinetics of intravenous flucloxacillin and amoxicillin in neonatal and infant cardiopulmonary bypass surgery.

OBJECTIVES: To determine the blood and tissue concentrations of flucloxacillin and amoxicillin during cardiopulmonary bypass (CPB) in infants weighing less than 5 kg. METHODS: Eleven patients aged between 3 and 60 days and weighing <5 kg. Intravenous flucloxacillin 30 mg kg(-1) and amoxicillin 30 mg kg(-1) were administered at time of anaesthesia. Blood and muscle samples were collected at four stages of the operation: immediately before commencement of CPB; before cross-clamping; after weaning of CPB; and at the time of skin closure. Concentrations, half-lives (t(1/2)), clearance and volume of distribution were calculated for both antibiotics in serum and tissue. RESULTS: After connection to CPB the mean serum concentration of flucloxacillin decreased by 42.5% from 75.5 to 43.4 mg l(-1) (P=0.003) and that of amoxicillin decreased by 36.2% from 73.3 to 46.7 mg l(-1) (P=0.021). Serum concentrations of the two antibiotics decreased by a further 16.5 and 14.5% during the remainder of the surgery, but remained >15-fold above the expected minimum inhibitory concentration (MIC) for target pathogens. Muscle concentrations of both antibiotics reached MIC values by the time of the first sample and there was no decrease associated with connection to CPB. Levels remained >8-fold above MIC for target pathogens throughout the procedure. The t(1/2) for flucloxacillin was 2.64(+/-0.23)h and for amoxicillin was 3.16(+/-0.29)h, both of which are more than double the values in normal adults. There was an equivalent reduction in clearance for both antibiotics. CONCLUSIONS: Single doses of flucloxacillin and amoxicillin at 30 mg kg(-1) maintain serum and muscle concentrations well above the MIC throughout cardiac surgery. This is partly due to a prolonged t(1/2) and reduced clearance of both antibiotics in infants.     

Effectiveness of highly active antiretroviral therapy among HIV-1 infected women

STUDY OBJECTIVE: To describe the impact of highly active antiretroviral therapy (HAART) on mortality, morbidity, and markers of HIV disease progression in HIV infected women. DESIGN: Data collected from the Women's Interagency HIV Study, a prospective cohort study that enrolled women between October 1994 and November 1995. SETTING: Six clinical consortia based in five cities in the United States (New York, NY; Washington, DC; Los Angeles, CA; San Francisco, CA; and Chicago, IL). PARTICIPANTS: A total of 1691 HIV seropositive women with a study visit after April 1996. MAIN RESULTS: Beginning in April 1996, the self reported use of HAART increased over time, with more than 50% of the cohort reporting HAART use in 1999. There was a 23% decline per semester in the incidence of AIDS from April 1996 (95% confidence intervals (CI) -29% to -16%). Furthermore, there was a 21% decline of the semiannual mortality rates among those with AIDS at baseline (95% CI -27% to -14%) and an 11% decline among those AIDS free at baseline (95% CI -3% to -18%). CD4+ lymphocyte counts either increased (women with baseline AIDS) or stabilised (women without baseline AIDS) after April 1996, and HIV RNA levels dramatically declined in both groups, although the percentage of women with HIV RNA above 4000 cps/ml remained stable at approximately 40% since mid-1997. CONCLUSIONS: Despite concerns regarding the use of antiretroviral therapies in this population, the use of therapies led to improved immunological function, suppressed HIV disease activity, and dramatic declines in morbidity and mortality.