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Biomedical subjects

J Oliver

Publications and source records attributed to J Oliver.

At least 73 records · Page 4Linked to original sources
PubMed1997

A study of HIV seroprevalence in a group of homeless youth in Hollywood, California.

The objective of this descriptive-exploratory study was to examine the HIV seroprevalence rate among a sample of homeless youth in Hollywood, California. A total of 96 respondents (age 14-24) were administered a questionnaire and had their blood drawn to test for the presence of HIV antibodies, during nightly street outreach activities conducted by Covenant House California. The HIV seroprevalence rate was 11.5% for the sample. Chi-square analysis showed strong correlation between HIV status and sexual risk behavior but not for HIV status and drug-related risk behavior.

Adolescent↗
PubMed1997

Vaccine evaluation studies of replication-defective SIVsmB7.

Non-infectious virus-like particles of SIVsmB7 that expresses env and gag gene products but are defective in pol and vpx/vpr were assessed for their ability to induce protective immunity against infection with pathogenic SIVsmE660 in rhesus macaques. Animals were immunized in three groups: group A was primed with cell-associated SIVsmB7 and boosted with cell-free SIVsmB7; group B was primed with cell-free SIVsmB7 and boosted with cell-free SIVsmB7 conjugated to iron oxide microbeads; group C was primed with cell-free SIVsmB7 mixed with Titer Max adjuvant and boosted with cell-free SIVsmB7 mixed with SAF-M adjuvant followed by secondary boosting with cell-free SIVsmB7 conjugated to microbeads. Animals were challenged intravenously with 20 animal infectious doses of SIVsmE660 grown in rhesus peripheral blood mononuclear cells 3 weeks after final boosting. All animals became infected as evidenced by quantitative virus cultivation. Sera from immunized animals contained low-titer antibodies by ELISA and low or undetectable neutralizing antibodies on the day of challenge but strong anamnestic antibody responses were observed following challenge. Interestingly, 2 of 3 animals in group A showed evidence of transient viremia and more stable CD4 counts following challenge as compared to the other immunized animals and to non-immunized controls. Thus, immunization with cell-associated SIVsmB7 did not provide sterilizing immunity against challenge with a highly pathogenic SIV strain but might have caused virus clearance later in infection.

Animals↗
PubMed1997

Impact of naled (Dibrom 14) on the mosquito vectors of eastern equine encephalitis virus.

In central New York, aerial mosquito adulticide applications have been used in response to eastern equine encephalitis (EEE) outbreaks and have targeted the swamp habitats of the primary enzootic vector of EEE virus, Culiseta melanura (Coquillett). The organophosphate insecticide naled (1, 2, dibromo-2, 2-dichloroethyl dimethyl phosphate) has been the insecticide of choice in this region. This study reports on analyses of 11 years (1984-94) of mosquito collection data from Cicero and Toad Harbor swamps in relation to applications of naled. Naled applications were successful in achieving short-term reductions in mosquito abundance. However, despite repetitive applications, populations of the primary vector of EEE virus, Cs. melanura, have increased 15-fold at Cicero Swamp. Preventive applications had no noticeable impact on the enzootic amplification of EEE virus, and isolations of virus following preventive applications have resulted in additional spraying. The possibility that applications of naled contributed to increased populations of Cs. melanura discredits the rationale that preventive applications of naled reduce the risk of EEE.

Animals↗
PubMed1996

Subtilisin BPN' at 1.6 A resolution: analysis for discrete disorder and comparison of crystal forms.

The three-dimensional structure of the serine protease subtilisin BPN' (SBT) has been refined at 1.6 A resolution in space group C2 to a final R value of 0.17. 17 regions of discrete disorder have been identified and analyzed. Two of these are dual-conformation peptide units; the remainder involve alternate rotamers of side chains either alone or in small clusters. The structure is compared with previously reported high-resolution models of SBT in two other space groups, P2(1)2(1)2(1) and P2(1). Apart from the surface, there are no significant variations in structure among the three crystal forms. Structural variations observed at the protein surface occur predominantly in regions of protein-protein contact. The crystal packing arrangements in the three space groups are compared.

Journal Article↗
PubMed1996

Outcome of grafts with long-lasting delayed function after renal transplantation.

To assess the impact of long-lasting acute renal failure after renal transplantation on late graft prognosis, we compared the risk factors and outcome in renal allografts with delayed function for >3 weeks after renal transplantation (long-lasting delayed graft function [LLDGF]) (group A, n=64), and in four control groups: group B, initially functioning grafts (n=322); group C, grafts with delayed function for <2 weeks after transplantation (n=110); group D, grafts with delayed function for 14 to 20 days after transplantation (n=57); and group E, never-functioning grafts (n=88). Donor asystolia or instability, stroke as a cause of donor's death, and prolonged cold ischemia and vascular surgical times were some predictors of LLDGF. Overlap was important, but 43% of patients of group A, 15% of group B, 25% of group C, 31% of group D, and 40% of group E (P<0.01) presented two or more risk factors for severe acute tubular necrosis after transplantation. Acute rejection and early complications were very frequent in group A. Also, patient survival was significantly decreased in group A, due to a higher incidence of infectious mortality. Graft survival was moderately (NS) decreased in group A. Serum creatinine was initially higher in patients of group A, but differences disappeared after the second year. However, late proteinuria was more frequent in group A, and there was also a trend for a higher prevalence of hypertension in this group. LLDGF cannot be reliably predicted at the time of renal transplantation. The main consequence of LLDGF is an excess mortality, while the impact on late graft function is less significant. Short-lasting delayed graft function does not seem to have a negative impact on the outcome of renal transplantation.

Acute Disease↗
PubMed1996

Evaluation of shelf arthroplasty as a treatment for hip dysplasia in dogs.

OBJECTIVE: To evaluate effects of shelf arthroplasty on coxofemoral joint laxity and progression of degenerative joint disease in young dogs with hip dysplasia. DESIGN: Prospective, controlled study. ANIMALS: 10 dogs between 10 and 24 months old and weighing between 20 and 27 kg. All dogs had bilateral coxofemoral joint laxity (i.e., an Ortolani's sign). PROCEDURE: In all dogs, shelf arthroplasty was performed on the right coxofemoral joints, and a sham procedure was performed on the left. Dogs were evaluated before and after surgery by means of lameness assessment, coxofemoral joint palpation and goniometry, thigh circumference measurement, and radiography. RESULTS: There were no significant changes in coxofemoral joint mobility, range of motion, joint laxity, degree of degenerative joint disease, or thigh circumference during the study. A greater amount of periacetabular bone formed on the right side than on the left side; however, dogs did not develop large bony shelves, and the amount of periarticular bone decreased over time. The polymer implants remained in their original position and were encapsulated by fibrous tissue. There was no histologic evidence of osteoconduction by the implants. CLINICAL IMPLICATIONS: The polymer implants used in this procedure do not appear to be osteoconductive. Shelf arthroplasty was associated with minimal morbidity and was not associated with serious adverse sequelae in this study, but the procedure did not alter the progression of hip dysplasia in these dogs. We cannot advocate shelf arthroplasty using this polymer as a treatment for dogs with hip dysplasia.

Animals↗
PubMed1996

Power spectral analysis of heart-rate variability reflects the level of cardiac autonomic activity in rabbits.

Power spectral analysis of heart rate (HR) variability was tested in conscious rabbits to assess the reliability of this method for assessing cardiac autonomic function in normal rabbits under resting conditions. Evaluation of power spectrum was performed in 5 rabbits under normal resting conditions and after sympathetic, parasympathetic and combined sympathetic plus parasympathetic blockade. Rabbits were randomly assigned to undergo sympathetic (propranolol) or parasympathetic (methscopolamine) blockade at the initial step followed by combined blockade. The power spectrum of heart-rate variability in rabbits was presented as one broad spectral component at frequencies mainly between 0 and 0.5 Hz. This component was considerably modulated by both sympathetic and parasympathetic influences with substantial overlap of sympathetic- and parasympathetic-related components of the spectrogram. Nevertheless, it was clearly shown that power of heart-rate variability at frequencies from 0.4373 Hz to 0.5625 Hz was determined only by parasympathetic influences, and sympathetic modulation of HR was presented mainly at frequencies from 0.0625 Hz to 0.1875 Hz. Spectral subcomponent analysis of the power spectrum of HR variability may be useful to follow changes in cardiac autonomic function in rabbits.

Adrenergic beta-Antagonists↗
PubMed1996

Splice site mutation causing deletion of exon 21 sequences from the pro alpha 2(I) chain of type I collagen in a patient with severe dentinogenesis imperfecta but very mild osteogenesis imperfecta.

An eight-year-old boy was referred for dental assessment of dentinogenesis imperfecta, a full clinical examination also revealed joint hypermobility and some features of mild osteogenesis imperfecta although he had suffered few fractures. Analysis of the collagens produced by both gingival and skin fibroblast cultures showed the synthesis and intracellular retention of an abnormal alpha 2(I) chain that migrated faster than normal on SDS-PAGE. Cyanogen bromide peptide mapping of this intracellular protein indicated a probable deletion in the N-terminal peptide alpha 2CB4. The denaturation temperature of the mutant protein was only 36 degrees C, some 6 degrees C below normal. At 37 degrees C secretion of abnormal protein was not detectable but a lower temperature (30 degrees C) some was secreted into the medium. RT-PCR amplification of mRNA coding for alpha 2CB4 revealed a heterozygous deletion of the 108 bp exon 21 of COL1A2. Sequencing of PCR amplified genomic DNA identified a G --> A transition in the moderately conserved + 5 position of the IVS 21 5' consensus splice site causing the skipping of exon 21. Hybridization with allele-specific oligonucleotides showed no other family member had this base change. Since the cDNA deletion was associated with the (-) allele of a Pvu II polymorphism in exon 25 of COL1A2 we could demonstrate that the mutant pre-mRNA was alternatively spliced yielding both full length and deleted transcripts. Family genotype analysis indicated the mutation had originated in the paternal alpha 2(I) gene.

Alternative Splicing↗
PubMed1996

The effects of interleukin-1 receptor antagonist protein (IRAP) infusion following spinal cord transection in rats.

A laminectomy was performed at the T5-T6 vertebral level in adult, male, Sprague-Dawley rats and the spinal cord transected with a scalpel. A group of sham animals was subjected to the same surgery without the transection step. A group of unhandled control rats was also included. A subgroup of transected animals received a subcutaneous osmotic minipump that dispensed IL-1 receptor antagonist protein (IRAP) at the transection site for 7 consecutive days. Another transected subgroup received a minipump that infused the vehicle only. IRAP-treated rats displayed a significant reduction in body temperature (p < 0.05) compared with vehicle-treated rats. The IRAP-treated rats were also less active when assessed for locomotor behavior using an HVS computerized tracking system (p < 0.01). IRAP treatment had no effect on serum corticosterone, beta-endorphin levels, Con A, PHA, or LPS-induced splenocyte mitogenesis when compared with vehicle-treated animals. However, half of the IRAP-treated animals exhibited a substantive reduction in the number of reactive astrocytes near the transection site, suggesting a possible effect of IRAP on astrocyte activation.

Animals↗
PubMed1996

The effect of interferon-alpha on the pituitary-adrenal axis.

This report concerns the use of a minimum stress animal model for evaluating the neuromodulatory effects of interferon-alpha (IFN-alpha). Male Sprague-Dawley rats, 350-450 g, received jugular catheters and were habituated to handling and sampling arenas. These procedures will minimize stress usually associated with i.v. injections and blood sampling. Natural rat IFN-alpha/beta (RaIFN-alpha/beta) endotoxin free (Lee Biomolecular Research Laboratories, San Diego, CA) or recombinant human IFN-alpha, (rHuIFN-alpha) (a gift from Hoffman La Roche, Nutley, NJ) was injected into rats via catheter at various IFN concentrations. Controls were injected with either (1) vehicle (saline), (2) human or bovine serum albumin in saline, or (3) heat-denatured RaIFN-alpha/beta. Experiments were begun (0 h) at about 0900 h, and blood samples were withdrawn at intervals up to 2 h after IFN or control injections and replaced by the same volume of saline. The concentrations of corticosterone and ACTH in peripheral plasma were measured by radioimmunoassay. Both IFN, when injected at concentrations of 300 or 600 U/g body weight (U/gbw), stimulated an increase above 0 h levels of both hormones in the same animals. Additionally, the stimulation was also evident when compared with plasma hormone levels in animals injected with control substance in a parallel time course. After administration of 150 U/gbw of either IFN, only the increase in the blood corticosterone was significant. These studies demonstrate that both homospecific (RaIFN-alpha/beta) and heterospecific (rHuIFN-alpha) IFN preparations are capable of stimulating the pituitary-adrenal axis.

Adrenal Cortex↗
PubMed1996

Evidence for multiple foci of eastern equine encephalitis virus (Togaviridae:Alphavirus) in central New York State.

A regional surveillance system for eastern equine encephalitis (EEE) virus was established in central New York in 1984 after the 2nd human EEE fatality occurred in 1983. Extensive mosquito surveillance activities were coordinated with the rapid laboratory processing of mosquito specimens for EEE virus. Active surveillance for EEE infections in humans and equines also was initiated. Results of long-term surveillance detected the presence of multiple Culiseta breeding swamps. A 6-yr interepizootic period (1984-1989) was followed by 2 yr of equine EEE. In 1990, there were 7 equine cases and a record number of EEE virus isolations from mosquitoes (n = 86), wild birds (n = 27), and sentinel pheasants (n = 7). In 1991, 7 equine cases also occurred, although there were fewer isolations from mosquitoes (n = 40). The sequence to the appearance of EEE virus at swamps and upland sites and at individual swam complexes, and the spatial and temporal distribution of equine cases provide evidence for multiple foci of EEE virus in central New York. The role of infected Culiseta melanura (Coquillett) in the transfer of EEE virus between swamp and upland areas and among swamp complexes is advanced.

Animals↗
PubMed1996

An apoptotic endonuclease activated either by decreasing pH or by increasing calcium.

DNA fragmentation in isolated nuclei from the murine IL3-dependent bone marrow cell line BAF3 could be stimulated either by decreasing pH below 6.5 or by adding microM calcium at neutral pH. An endonuclease which could also be stimulated either by a decrease in pH, to 6.5, or by the presence of microM calcium at neutral pH, was purified 10(4)-fold from nuclei of BAF3 cells. Digestion of DNA with the purified enzyme resulted in 5'-terminal hydroxyl and 3'-terminal phosphate ends. These characteristics are distinct from those described for other mammalian endonucleases. The possible role of this enzyme in genome digestion during apoptosis is discussed.

Animals↗
PubMed1996

The respiratory effects of reduction of mite allergen in the bedrooms of asthmatic children--a double-blind controlled trial.

BACKGROUND: Inhalation of house dust mite (HDM) allergen may provoke attacks of asthma. OBJECTIVE: We investigated whether a double-blind placebo-controlled community-based study aimed at reducing the HDM allergens in the bedrooms of HDM sensitive asthmatic children using the best methods available would prove beneficial to the children's health. METHODS: The children (mean age 9.9 years, 34 boys) were recruited by a questionnaire submitted to 7386 families in a geographically-defined area of the UK. Subjects were chosen to take part in the double-blind placebo-controlled trial if they were asthmatic, skin sensitive to mites, and had mite allergen in their mattresses. Seventy children were randomly allocated to groups. In the active group, the children's bedrooms were treated with an acaricide (Acarosan) and the mattresses, pillows and duvets were encased in exclusion covers. The control group received placebo treatments. RESULTS: Forty-nine complete data sets were obtained. Applying bedding covers and Acarosan led to a median reduction of 480 ng (100%) in mite allergen on the mattress vs 215 ng (53%) reduction in placebo-treated group by 6 weeks. No evidence was found that the acaricide reduced mite allergen level. A change in bronchial reactivity to histamine was observed in the children after 6 weeks. This was not associated with any change in thrice-daily records of peak expiratory flow rate. By 24 weeks, the actively-treated children had improved forced expiratory volume in 1s (FEV1) and fewer required bronchodilator therapy or reported asthmatic symptoms than did the controls. CONCLUSIONS: The results suggest that mite removal procedures may modestly improve mite-sensitive asthmatics and could perhaps be of value in exceptionally mite-sensitive and/or highly mite-exposed individuals whose response to the attempted removal should be measured.

Allergens↗
PubMed1996

Delayed graft function after renal transplantation in patients undergoing peritoneal dialysis and hemodialysis.

We have compared the incidence of delayed graft function (DGF) after renal transplantation in our patients undergoing peritoneal dialysis (PD) (group A, n = 92) or hemodialysis (HD) (group B, n = 587), analyzing the prevalence of the main risk factors for DGF in both groups. Both groups were comparable, except for a higher prevalence of diabetes (p < 0.05) and a shorter time on dialysis (p < 0.01) in group A. Immediate graft function occurred in 68.5% of group A and 46.5% of group B, DGF in 22.5% of group A and 39.5% of group B, and there was never any function in 9% of group A and 14% of group B (p < 0.001). When potential risk factors for DGF were compared, no relevant differences could be found. HD was performed more frequently immediately before surgery in group B (p < 0.001), but statistical analysis showed no impact of this measure on the incidence of DGF. In conclusion, in our population, patients on PD present higher rates of immediate graft function after renal transplantation than patients on HD. The explanation for the difference is not clear, but seems to be related to the dialysis modality itself, as the profile of risk factors for DGF is very similar in both populations.

Adult↗
PubMed1996

Fecundity of naturally bloodfed Culiseta melanura.

Naturally bloodfed Culiseta melanura were collected annually from resting boxes in and around a swamp in Oswego County, NY from 1982 to 1989. Females were held individually in a laboratory until they oviposited. Except in 1982, every other female was provided a 10% dextrose solution. Females were classed as alive or dead following oviposition and female size was based on abdomen length, measured after oviposition. Egg rafts from each female were held individually and the numbers of larvae and unhatched eggs were counted. Fecundity (number of eggs laid per female) was based on number of larvae plus unhatched eggs. Rafts from 2,120 females averaged 129 eggs and 106 larvae per raft. Rafts from females that were alive following oviposition were significantly larger and produced more larvae than those of females that died following oviposition. Availability of sugar influenced female survival but not egg raft production. Size and fecundity of females decreased from May through September. These differences were attributed to the temperature and larval density of breeding crypts. Seasonal changes in size may influence the vector efficiency of Cs. melanura.

Animals↗