Search PubMed⌕ Search

Biomedical subjects

V A Brown

Publications and source records attributed to V A Brown.

At least 19 recordsLinked to original sources
PubMed2003

Influence of carbohydrate ingestion on immune changes after 2 h of intensive resistance training.

Thirty strength-trained subjects were randomized to carbohydrate (CHO) or placebo (Pla) groups and lifted weights for 2 h (10 exercises, 4 sets each, 10 repetitions, with 2- to 3-min rest intervals). Subjects received 10 ml x kg(-1) x h(-1) CHO (6%) or Pla beverages during the weight training bout. Blood, saliva, and vastus lateralis muscle biopsy samples were collected before and after exercise. Blood cell counts were determined, and plasma was analyzed for IL-6, IL-10, IL-1 receptor antagonist (IL-1ra), IL-8, and cortisol. Muscle was analyzed for glycogen content and relative gene expression of 13 cytokines (IL-1alpha, IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p35, IL-12p40, IL-15, IFN-gamma, TNF-alpha) by use of real-time quantitative RT-PCR. Significant but modest increases were measured for plasma IL-6, IL-10, IL-1ra, and IL-8, but the pattern of increase did not differ between CHO and Pla groups. The rate of decrease in muscle glycogen content did not differ between CHO and Pla (P = 0.463). Muscle cytokine mRNA was detected preexercise for IL-1beta, IL-6, IL-15, IL-8, and TNF-alpha, and of these, IL-1beta, IL-6, IL-8, and TNF-alpha were significantly increased after the 2-h weight training bout. The increase in mRNA (fold difference from preexercise) did not differ between CHO and Pla groups. In summary, CHO vs. Pla ingestion did not alter modest increases measured for plasma IL-6, IL-10, IL-1ra, and IL-8, and muscle gene expression for IL-1beta, IL-6, IL-8, and TNF-alpha in strength-trained subjects lifting weights intensively for 2 h.

Administration, Oral↗
PubMed2001

Effects of acid treatment on the trace metal content of chromatographic silica: bulk analysis, surface analysis and chromatographic performance of bonded phases.

A series of studies has been carried out on the effect of refluxing silica chromatography particles for 0.5 h and 18 h in water, dilute hydrochloric acid and dilute hydrofluoric acid. The bulk and surface trace metal concentrations were measured by inductively-coupled plasma atomic emission spectroscopy, static secondary ion mass spectrometry (SSIMS) and X-ray photoelectron spectroscopy. Diffuse reflectance Fourier transform infrared spectroscopy was used to determine changes in 'isolated" and "bonded" silanol groups. The chromatographic behaviour of a series of weakly basic analytes was investigated on C8 and C18 bonded phases manufactured from the acid-treated silicas. The different reflux treatments all resulted in a reduction in the numbers of isolated silanols compared with the untreated silica and SSIMS analysis suggested that the HF-treated silicas had undergone a more efficient surface rehydroxylation. Bulk trace metals were removed most effectively by the HF treatment, with the multivalent elements (Ti and Al) being the most difficult to remove. Surface specific analysis suggested that trace metals were removed more rapidly from the surface of the silica compared to the bulk matrix and that the acid treatments resulted in halide contamination of the silica surface. Evidence is presented to suggest that the bulk metal content of the silica is not representative of the concentration of metals at the chromatographic surface. The chromatographic investigations showed that the HF-treated silica gave substantially better performance towards weak bases than the HCl-treated silicas.

Acids↗
PubMed2000

Influence of surface carbon coverage of C1 (TMS) stationary phases on the separation of nonylphenol ethoxylate ethoxymers.

The determination of surfactants in surface waters is required owing to their toxicity to aquatic micro-organisms and potential as endocrine disrupters. We have previously reported a method for the simultaneous separation of linear alkyl benzene sulfonates (LAS) and nonylphenol ethoxylates (NPEO) by high-performance liquid chromatography using a C1 (TMS) column. In this earlier work we discussed some problems with the resolution of individual ethoxymers from NPEO using C1 columns from different manufacturers. Here, we postulate that this phenomenon may be linked to carbon coverage of the C1 (TMS) stationary phases and study this utilising both elemental (bulk) analyses and surface specific analyses by X-ray photoelectron spectroscopy. Data obtained indicate that for the simultaneous separation of the LAS homologues and ethoxymers of NPEO, the stationary phase must have some trimethylsilyl groups bound to the surface of the silica in order to achieve separation of the LAS homologues, however the degree of surface coverage must not be greater than ca. 0.5 micromol/m2 in order to achieve adequate resolution of the NPEO ethoxymers. These data support earlier evidence for a "pseudo" reversed-phase mechanism for this separation.

Carbon↗
PubMed1993

Molecular epidemiology of a parainfluenza type 3 virus outbreak on a pediatric ward.

Parainfluenza type 3 virus (PIV-3), an important cause of acute lower respiratory illness in children, can be transmitted nosocomially. To differentiate between nosocomial transmission and community-acquired infection, a polymerase chain reaction-based sequencing assay was developed for the 5' noncoding region of the PIV-3 fusion protein gene and was applied to virus specimens from 10 children infected with PIV-3 during a hospital outbreak. Four strains of PIV-3 were identified among the 10 virus isolates. Six isolates, which appeared to belong to 1 strain, were obtained from a cluster of nosocomial cases in a pediatric intermediate care unit. In contrast, the remaining 4 isolates, which appeared to belong to 3 different strains, were obtained from children infected in the community or elsewhere in the hospital. These data indicate that multiple strains of PIV-3 can be found during a single epidemic and provide evidence that infections within the intermediate care unit were probably caused by transmission of 1 strain of virus within the unit rather than reintroduction of virus by new patients or staff.

Base Sequence↗
PubMed1990

Probe, VK5B, is located in the same interval as the autosomal dominant adult polycystic kidney disease locus, PKD1.

The polymorphic DNA probe VK5B (D16S94) was mapped by genetic linkage in families from the Centre d'Etude de Polymorphisme Humain (CEPH) as being in the same interval as the autosomal dominant adult polycystic kidney disease locus (PKD1). The maximum likelihood estimate of the genetic location of VK5B using multipoint linkage analysis was 9.6 cM proximal to 3'HVR (D16S85) and 5.4 cM distal to CRI-0327 (D16S63), in males. The VK5B probe may be useful in PKD1 families for prenatal and presymptomatic diagnosis of the disease. Additional typing of PKD1 families is required to determine whether the location of VK5B is distal or proximal to (PKD1).

Adult↗
PubMed1990

Genetic linkage map of 46 DNA markers on human chromosome 16.

We have constructed a genetic linkage map of human chromosome 16 based on 46 DNA markers that detect restriction fragment length polymorphisms. Segregation data were collected on a set of multigenerational families provided by the Centre d'Etude du Polymorphisme Humain, and maps were constructed using recently developed multipoint analysis techniques. The map spans 115 centimorgans (cM) in males and 193 cM in females. Over much of the chromosome there is a significantly higher frequency of recombination in females than males. Near the alpha-globin locus on the distal part of the short arm, however, there is a significant excess of male recombination. Twenty-seven (59%) of the markers on the map have heterozygosities greater than or equal to 0.50. The largest interval between loci on the sex-average map is 14 cM and the average marker spacing is 3 cM. Using loci on this map, one could detect linkage to a dominant disease on chromosome 16 with as few as 10-15 phase-known meioses.

Animals↗
PubMed1989

An extremely polymorphic locus on the short arm of the human X chromosome with homology to the long arm of the Y chromosome.

A genomic DNA clone named CRI-S232 reveals an array of highly polymorphic restriction fragments on the X chromosome as well as a set of non-polymorphic fragments on the Y chromosome. Every individual has multiple bands, highly variable in length, in every restriction enzyme digest tested. One set of bands is found in all males, and co-segregates with the Y chromosome in families. These sequences have been regionally localized by deletion mapping to the long arm of the Y chromosome. Segregation analysis in families shows that all of the remaining fragments co-segregate as a single locus on the X chromosome, each haplotype consisting of three or more polymorphic fragments. This locus (designated DXS278) is linked to several markers on Xp, the closest being dic56 (DXS143) at a distance of 2 cM. Although it is outside the pseudoautosomal region, the S232 X chromosome locus shows linkage to pseudoautosomal markers in female meiosis. In determining the X chromosome S232 haplotypes of 138 offspring among 19 families, we observed three non-parental haplotypes. Two were recombinant haplotypes, consistent with a cross-over among the S232-hybridizing fragments in maternal meiosis. The third was a mutant haplotype arising on a paternal X chromosome. The locus identified by CRI-S232 may therefore be a recombination and mutation hotspot.

Cell Line↗
PubMed1989

OKN asymmetries and binocular function in amblyopia.

Asymmetrical optokinetic nystagmus (OKN) means that OKN has a lower gain (slow-phase eye velocity/stimulus velocity) for monocular temporalward than nasalward visual field motion. OKN tends to be asymmetric in amblyopia, leading to suggestions of a link between OKN asymmetry and binocularity in the literature. The present study measured OKN in 13 amblyopes and five normal subjects. In an attempt to identify those binocular cells used in the OKN response, the degree of OKN asymmetry was compared with binocularity assessed by two different techniques: (1) stereopsis and (2) interocular transfer of threshold elevation (IOT). Horizontal monocular OKN was recorded for three different stimulus velocities in each subject. All the amblyopes were found to be stereoblind, although three amblyopes showed OKN asymmetries close to those found for the normal group. More association was seen between interocular transfer of the threshold elevation and OKN asymmetry; not all amblyopes demonstrated reduced IOT, but those amblyopes with no IOT all had OKN asymmetries more than 125% of the mean of the normal group. However, no association was seen between the amount of OKN asymmetry and the degree of IOT. The results are discussed in terms of the role of different groups of binocular neurones for OKN and the effect of the sensitive periods of development on these binocular neurones.

Amblyopia↗
PubMed1989

Chromosomal assignment of 14 genomic probes for highly polymorphic loci.

Over 500 probes revealing restriction fragment length polymorphisms (RFLPs) have been isolated by Schumm et al. (1988). We describe here the chromosomal assignment of 14 of the most highly polymorphic markers in that set of probes, with polymorphism information content values of up to 0.98. The probes were mapped using a panel of human x rodent somatic cell hybrids and were found to be distributed among nine different autosomes. Chromosome localization of such highly polymorphic markers has been an important step in the construction of the human genetic map, as a large number of RFLP probes has now been localized by genetic linkage studies to these loci.

Animals↗
PubMed1988

Regional localization of the autosomal dominant polycystic kidney disease locus.

The localization of the autosomal dominant polycystic kidney disease locus (PKD1) within an array of anonymous polymorphic DNA sequences on chromosome 16 band p13 was determined by multipoint mapping. Nine polymorphic DNA markers, including two hypervariable sequences, were used to study 19 PKD1 and 21 reference families. PKD1 was found to lie proximal to the 3' and 5' hypervariable regions of alpha-globin and distal to the anonymous sequence CRI-0327. Somatic cell hybrid mapping places PKD1 within the region 16p13.11-16pter. The availability of an array of linked markers which bracket the PKD1 locus provides a framework for further attempts to identify the PKD1 gene and offers an improved method of presymptomatic diagnosis of the disease.

Animals↗
PubMed1988

Identification of more than 500 RFLPs by screening random genomic clones.

As part of our genome-mapping effort, we undertook a large-scale screening study to identify RFLPs useful as genetic markers. Some 1,664 single-copy or repeat-containing phage clones from a Charon 4A genomic library were tested for polymorphism against a panel of DNAs, from five unrelated individuals, digested with eight restriction enzymes. Approximately 30% (515) of the clones revealed polymorphism by Southern hybridization; 67 loci detected had PIC values greater than .5. Restriction enzymes MspI, TaqI, and RsaI were most efficient in detecting polymorphism within the 1-20-kb-fragment size range resolved. With only one exception each of the clones detected polymorphism originating from a single locus.

Cloning, Molecular↗
PubMed1987

Use of DNA restriction fragment length polymorphisms to document marrow engraftment and mixed hematopoietic chimerism following bone marrow transplantation.

We have studied the feasibility of using DNA restriction fragment-length polymorphisms (RFLP) to study marrow engraftment in 27 patients after allogeneic bone marrow transplantation, and have compared these results with those obtained using red blood cell antigens, cytogenetics, and immunoglobulin allotypes. Using highly polymorphic DNA probes, we have documented stable chronic mixed hematopoietic chimerism, have identified transient mixed chimeras, have excluded mixed chimerism with high probability in retrospective studies even when a pretransplant DNA sample was not available, have documented marrow engraftment in the early posttransplant period, and have studied the origin of leukemic cells in patients with recurrent disease. We have evaluated the advantages and disadvantages of several genetic markers and have developed tentative statements concerning the prognosis of patients with mixed chimerism. We conclude that DNA RFLP are powerful and practical genetic markers in bone marrow transplantation studies and that further studies of mixed hematopoietic chimerism are warranted.

Antigens, Surface↗
PubMed1987

Postpartum haemorrhage--a continuing problem.

The factors responsible for postpartum haemorrhage (PPH) in singleton vaginal deliveries, not complicated by a retained placenta, were identified by comparing labour characteristics in 86 women who had a PPH (blood loss greater than 500 ml) with 351 women whose blood loss at delivery was less than 350 ml. Primiparity, induction of labour by amniotomy/oxytocin, forceps delivery, long first and second stages, oxytocin compared with syntometrine (oxytocin plus ergometrine maleate), as a prophylactic oxytocic, were identified as significant risk factors. Epidural analgesia contributed indirectly to an increase in the risk of postpartum haemorrhage. The changes in labour ward practice over the last 20 years have resulted in the re-emergence of PPH as a significant problem.

Amnion↗
PubMed1987

Mixed hematopoietic chimerism following bone marrow transplantation for hematologic malignancies.

Twenty-nine of 172 patients (17%) who received an allogeneic bone marrow transplant (BMT) from histocompatible sibling donors for hematologic malignancies were mixed hematopoietic chimeras; ie, they had a mixture of donor and host hematopoietic or lymphohematopoietic cells at greater than or equal to 14 days after transplantation. Twenty-four of the 29 mixed chimeras (83%) have remained in continuous complete remission for up to 116 months (greater than 9 years) following BMT. Four of the 29 patients (14%) have had recurrent leukemia, and 7 of the 29 (24%) have had moderate or severe graft-v-host disease (GVHD). Twelve of these 29 patients have persisted as stable mixed chimeras for greater than or equal to 2 years after BMT, whereas other patients converted to all donor-type hematopoiesis. The incidence of mixed chimerism was independent of the pretransplant regimen, the donor or recipient age (less than 20 v greater than 20 years), remission status (first complete remission of acute leukemia and first chronic phase of chronic myelocytic leukemia v later stages of disease), and type of leukemia. Our data indicate that mixed hematopoietic chimerism is not rare after BMT for hematologic malignancies and that its presence is compatible with long-term disease-free survival. Prospective studies of mixed chimerism after BMT are warranted to achieve better understanding of its biologic importance.

Acute Disease↗
PubMed1987

The use of computerized contrast sensitivity, Arden gratings and low contrast letter charts in the assessment of amblyopia.

Contrast sensitivity measured with an electronic display was compared with Arden gratings and low contrast letter charts in normal and amblyopic children and adults. The low contrast letter charts and the Arden gratings used in the conventional manner revealed no additional information over that obtained by conventional Snellen acuity. However, the interocular differences found with each plate of the Arden gratings compared favourably with the computerized CSF. With the addition of an extra plate to test at a higher spatial frequency, the Arden gratings would be a useful technique for monitoring amblyopia therapy.

Adult↗