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Biomedical subjects

G A Wilson

Publications and source records attributed to G A Wilson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Genetic variation within and relatedness among wood and plains bison populations.

There are two recognized subspecies of bison, wood (Bison bison athabascae) and plains (Bison bison bison) bison. The establishment of most bison populations from a small number of individuals has raised concerns about their genetic variation. To this end, 11 bison populations were surveyed with 11 microsatellite loci in order to calculate genetic variation and genetic distances. Mean number of alleles ranged between 3.18 at Antelope Island State Park (Utah) and 6.55 at Wood Buffalo National Park (Alberta and Northwest Territories). Mean heterozygosity ranged from 0.295 at Antelope Island State Park to 0.669 at Custer State Park (South Dakota). The amount of genetic variability present in the bison populations as measured by mean number of alleles and overall probability of identity was found to correlate with the number of founders for all sampled populations. The G-test for heterogeneity revealed some evidence for the existence of subpopulations at Wood Buffalo National Park, however very small genetic distances between these subpopulations suggest that nuclear material from the plains bison introduced into Wood Buffalo National Park has diffused throughout the park. Genetic distances between the sampled populations were generally larger between than within the two bison subspecies.

Alleles↗
PubMed1999

Report from the National Transplantation Pregnancy Registry (NTPR): outcomes of pregnancy after transplantation.

Specific data on pregnancies following transplantation continue to accrue in the National Transplantation Pregnancy Registry (NTPR) in each type of organ recipient, with the following conclusions: 1. While the majority of kidney recipients appear to tolerate pregnancy well, a small percentage develops rejection, graft dysfunction and/or graft deterioration. Overall, there is a slight increase in the mean postpartum creatinine level when compared with the prepregnancy level, which has been noted in previous investigations by the NTPR. One neonatal death attributed to thrombotic cardiomyopathy was noted in a set of twins of a tacrolimus-based kidney recipient, but no other death has been noted in any of the additional reports among the recipients given newer immunosuppression regimens. Follow-up of offspring of these recipients is ongoing. 2. No structural malformations have been noted among offspring exposed to mycophenolate mofetil, but exposures are limited. (5 mothers, 29 fathers). 3. Female liver recipients with biopsy-proven acute rejection during pregnancy appear to be at greater risk for both poorer newborn outcomes and recurrent rejection episodes. In the setting of acute rejection diagnosed during pregnancy, close attention is warranted, anticipating that birthweight may be lower and that a substantial percentage of these female recipients may have recurrent rejection episodes. 4. Pancreas-kidney grafts can maintain normoglycemia throughout pregnancy. A high incidence of maternal hypertension, prematurity and low birthweight have been noted, so, as in other recipient groups, these are high-risk pregnancies. Maternal pancreas and kidney function must be closely monitored. 5. No specific prepregnancy predictors of adverse outcomes have yet been identified among heart or lung recipients although none of the deaths among heart recipients in the NTPR database occurred within 2 years of delivery. When compared with other solid organ recipients, female lung recipients may face higher risks, particularly related to rejection. Whether prepregnancy factors can help to predict either heart or lung recipients at risk requires continued study. 6. No structural malformations or significant learning disabilities have been noted in follow-up of the offspring of CsA-treated females, the largest group of offspring followed to date with a mean age of 4-5 years. Continued surveillance of children will be essential to determine if effects become apparent as age-related developmental delays or other problems in immune function or fertility later in life. 7. Newer regimens as well as new combinations of agents will continue to be studied. It is essential that non-viable as well as viable pregnancy outcomes be reported to the registry (i.e., recipients with pregnancies that result in spontaneous abortion or termination should be included for study). True estimates of non-viable outcomes have been difficult to assess. Additionally, inclusion of reports of pathologic evaluations at delivery hospitals will be helpful to determine whether spontaneous abortions are a result of lethal malformations related to immunosuppressive or other medication exposure. Safety of pregnancy for parent and child remain the primary goals of the NTPR.

Abortion, Spontaneous↗
PubMed1998

Determination of leucocyte antibody binding capacity (ABC): the need for standardization.

The flow cytometric determination of antigen density, or cellular antibody binding capacity, is now an accepted technique for the characterization of cells in health and disease. In HIV infection, for example, antigen density changes in CD38 expression may be an important indicator of disease progression. Our experience of using one such method, Quantum Simply Cellular, which measures antibody binding capacity (ABC), has highlighted several technical factors which can affect the results. We report the influence of pH, incubation temperature and time, antibody fluorochrome and titre, as well as lysing reagent (FACS Lysing Solution v. Ortho-mune Lysing Reagent) on the ABC of anti-CD3, CD4 and CD8 of normal lymphocytes. In addition, the effect of single, double or triple-staining was assessed. The results indicate that the ABC values are influenced by all the variables studied. The pH range tested (6.0-9.0) demonstrated that pH 7.4 gave maximal binding. Furthermore, temperature also influenced the pH of the two lysing solutions, and thus potentially the ABC. Antibody concentration, fluorochrome and staining technique are also important factors with an observed difference of up to 458,855 ABC between the various fluorochromes. In addition a maximal difference of 130,119 ABC was observed between single and triple staining techniques. In conclusion, if antigen quantification is to be used in the clinical setting, an internationally standardized method is required to ensure the reproducibility of results from centre to centre. Our data suggests that single staining, using fluorescein isothiocynate (FITC) conjugated antibodies with all reagents at pH 7.4 + 0.1, with incubation and lysing carried out at 20 + 1 degrees C, could be used as a 'benchmark' method for ABC determination using the QSC system.

Antigen-Antibody Reactions↗
PubMed1996

Evaluation of a novel stable whole blood quality control material for lymphocyte subset analysis: results from the UK NEQAS immune monitoring scheme.

The UK NEQAS immune Monitoring Scheme (UK NEQAS) evaluates the performance of laboratories routinely performing T-lymphocyte subset analysis on HIV-infected individuals. The scheme originally issued fresh whole blood, but a significant problem was that of analyte stability, especially 36 h postphlebotomy. To circumvent this problem, we have developed a novel stabilisation procedure that ensures retention of leucocyte light scatter and immunological staining characteristics for up to 300 days. In addition, the stabilised whole blood preparation is fully compatible with flow cytometer technology, incorporating either whole blood lysis or "no wash, no lyse" techniques. The ranges of interlaboratory coefficient of variation for the stabilised material are now tighter than those previously obtained with fresh whole blood. Development of this novel material has enabled overseas laboratories to participate in the UK NEQAS immune Monitoring Scheme and could in the future lead to the production of reference and/or calibration reagents for leucocyte immunophenotyping.

B-Lymphocytes↗
PubMed1996

Validation of three paediatric pain scores for use by parents.

Twenty children undergoing general surgery and 20 children undergoing otorhinolaryngological surgery were simultaneously assessed on two occasions by a doctor and a parent using three pain scoring systems. The pain scoring systems used were the Objective Pain Score, a four point numerical score and a 100 mm visual analogue scale. There was a high correlation between the scores given by the doctor and by the parents for all three scoring systems with parents consistently giving slightly higher scores than the doctor. The correlation coefficients for parental and medical pain scores in recovery were 0.77 for the Objective Pain Score, 0.70 for the four point numerical score and 0.69 for the visual analogue scale (p < 0.01). At 1 h after leaving the recovery area the correlation coefficients were 0.81, 0.80 and 0.73 respectively (p < 0.01). These results suggest that parental scoring of pain in children will be useful in future audit and research of analgesic regimens, particularly in day-case surgery.

Analgesics↗
PubMed1995

Impact of serum lipids on long-term graft and patient survival after renal transplantation.

The results after primary cadaveric renal transplantation in 665 consecutive patients were reviewed with respect to posttransplant serum lipids. Data were available for 182 of 665 patients on serum total cholesterol and triglycerides at 1 year posttransplant. Hypercholesterolemia (cholesterol > 200 mg/dl) developed in 141 of 182 patients (77%) and hypertriglyceridemia developed in 73 of 166 patients (44%). At 1 year posttransplant, hypercholesterolemia and hypertriglyceridemia both correlated with age at transplant (P = 0.0001, P = 0.01). Hypercholesterolemia and hypertriglyceridemia were also correlated with obesity as determined by body mass index (kg/m2) (P = 0.006, P = 0.01). Hypertriglyceridemia at 1 year posttransplant correlated with pretransplant triglyceride level (P = 0.006), but hypercholesterolemia did not correlate with pretransplant cholesterol level (P = 0.53). Hyperlipidemia was not correlated with cyclosporine (CsA) or prednisone dose (mg/kg), CsA trough levels, number of rejection episodes, or serum creatinine at 1 year. Despite significant differences in serum cholesterol and triglycerides, actuarial graft and patient survival were similar between the normolipidemic and hyperlipidemic groups.

Adult↗
PubMed1995

Obesity as a risk factor after combined pancreas/kidney transplantation.

The impact of pretransplant overweight/obesity was analyzed in a group of 268 consecutive primary pancreas renal transplant recipients. Obesity was defined as body mass index (BMI) greater than 27 kg/m2. BMI was available for 240 of the 268 patients. A total of 88% (212/240) of the patients had a BMI < or = 27 and 28/240 (12%) had BMI > 27. There were no significant differences in age, sex, or race between obese and nonobese patients. The incidence and degree of posttransplant hypertension, weight gain, increase in BMI, and hyperlipidemia did not differ on the basis of pretransplant BMI. Serum creatinine at one year posttransplant was slightly increased in obese patients, but the increase was not statistically significant. Cumulative prednisone dose (mg/kg) as well as cyclosporine (CsA) dose (mg/kg) at one year was not significantly different between obese and nonobese patients. However, there was a marginally significant negative correlation between BMI and one-year cumulative (mg/kg) prednisone dose (P = .06). Types and frequency of posttransplant complications were similar between obese and nonobese patients, although there was a slightly higher incidence of wound related complications in obese patients (11% vs. 6.8%) (P = NS). There was no difference in the frequency of acute rejection episodes in obese and nonobese patients. Actuarial patient survival was comparable between patients with BMI < or = 27 versus those with BMI > 27 (P = .10). However, actuarial graft survival, both pancreas and renal, were significantly decreased in patients with BMI > 27 (P = .029). The decrease in pancreas and kidney graft survival in obese patients could not be attributed to decreased "early" patient survival, increased incidence of perioperative or postoperative complications, differences in hypertension, acute rejection episodes, serum lipids, or immunosuppression dosage. The most common causes of graft loss were rejection and patient death in both obese and nonobese patients. After three years posttransplant, the decreased pancreas and renal graft survival in obese patients corresponded to decreased patient survival. The most common cause of patient death was cardiovascular complications in both obese and nonobese PKT recipients.

Adult↗
PubMed1995

Typing and subtyping of influenza viruses in clinical samples by PCR.

Type A and B influenza viruses can cause a wide spectrum of illness, and these viruses are responsible for considerable mortality and morbidity. Rapid typing of isolates is desirable when amantadine treatment or prophylaxis of contacts of type A influenza virus carriers is considered, but the available rapid techniques lack sensitivity and standard diagnostic methods require expansion of virus in tissue culture or embryonated hens' eggs. We developed a series of oligonucleotide primers able to detect, type, and subtype type A influenza viruses in a single reverse transcription-PCR. RNA was isolated from clinical specimens, and cDNA was generated with random primers. PCR was carried out with a mixture of primers specific for influenza viruses of types B, A/H1 and A/H3, and subtyping of the neuraminidase was carried out on the same cDNA template under identical conditions. Amplified products were detected by ethidium bromide staining of amplified products after agarose gel electrophoresis. When it was used to test 98 clinical specimens, this method was comparable to standard culture techniques in the detection, typing, and subtyping of influenza viruses.

Base Sequence↗
PubMed1995

Circulating CD20dim T-lymphocytes increase with age: evidence for a memory cytotoxic phenotype.

The CD20 antigen has been regarded as a B lineage specific, 35 kDa, non-glycosylated membrane phosphoprotein, which functions as either a Ca2+ ion channel or as a regulatory protein of such a channel. Weak expression of CD20 (CD20dim), however, has recently been reported on a sub-population of T lymphocytes. We present results which confirm the existence of a CD20dim T lymphocyte population and show that such cells have a reduced antibody-binding capacity, when compared to CD20bright B-cells (10337 +/- 642 and 346311 +/- 24264 respectively). In addition, CD20dim cell counts vary with age, with the highest levels occurring in octogenarians: cord blood 0.3 +/- 0.1% (n = 13), 20-60 year-old group 2.1 +/- 1.1% (n = 18) and individuals > or = 61 years of age 6.9 +/- 3.2% (n = 10) (P < 0.001). Further characterization of CD20dim T cells, using three colour flow cytometry, demonstrated a predominantly memory cytotoxic phenotype, in that the cells were CD8+CD28+CD45RO+T-CR alpha beta +CD38-HLA-DR-.

Adult↗
PubMed1994

Association of the reovirus S1 gene with serotype 3-induced biliary atresia in mice.

A panel of serotype 3 (T3) reovirus strains was screened to determine their relative capacities to cause lethal infection and hepatobiliary disease following peroral inoculation in newborn mice. A wide range of 50% lethal doses (LD50s) was apparent after peroral inoculation of the different virus strains. Two of the strains, T3 Abney and T3 clone 31, caused mice to develop the oily fur syndrome associated with biliary atresia. The capacity to cause biliary atresia was not related to the capacity to cause lethal infection, however, because the LD50s of T3 Abney and T3 clone 31 were grossly disparate. Examination of liver and bile duct tissues revealed histopathologic evidence of biliary atresia and hepatic necrosis in T3 Abney-infected mice but not in mice inoculated with a T3 strain of similar virulence or with the hepatotropic T1 Lang strain. The consistency with which T3 Abney-infected mice developed biliary atresia-associated oily fur syndrome permitted us to determine the viral genetic basis of reovirus-induced biliary atresia. Analysis of reassortant viruses isolated from an in vitro coinfection with T3 Abney and T1 Lang indicated a strong association of the hepatobiliary disease-producing phenotype with the T3 Abney S1 gene, which encodes the viral cell attachment protein, sigma 1. Amino acid residues within the sigma 1 protein that were unique to disease-producing T3 strains were identified by comparative sequence analysis. Specific changes exist within two regions of the protein, one of which is thought to be involved in binding to host cell receptors. We hypothesize that changes within this region of the protein are important in determining the tropism of this virus for bile-ductular epithelium.

Amino Acid Sequence↗
PubMed1994

Proteolytic processing of reovirus is required for adherence to intestinal M cells.

Reovirus adheres specifically to apical membranes of mouse intestinal M cells and exploits M-cell transepithelial transport activity to enter Peyer's patch mucosa, where replication occurs. Proteolytic conversion of native reovirus to intermediate subviral particles (ISVPs) occurs in the intestine, but it is not known whether conversion is essential for interaction of virus with M cells. We tested the capacity of native virions, ISVPs, and cores (that lack outer capsid proteins) to bind to intestinal epithelial cells in vivo and found that only ISVPs adhered to M cells. Thus, intraluminal conversion of native reovirus to ISVPs is a prerequisite for M-cell adherence, and outer capsid proteins unique to ISVPs (either sigma 1 or products of mu 1) mediate interaction of virus with M-cell apical membranes.

Animals↗
PubMed1994

URTI management.

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Family Practice↗
PubMed1993

Ablation of remaining functioning thyroid lobe with radioiodine after hemithyroidectomy for carcinoma.

Nineteen patients who had hemithyroidectomy as a surgical procedure for thyroid cancer were given radioiodine to ablate the residual hemithyroid. Two different protocols were used, with either a larger single dose or multiple smaller doses. Ablation was achieved in 28% with the single large dose approach and in 33% of patients given split doses of similar total amount. This response to the initial attempt at eradication of the residual normal hemithyroid is considerably lower than the accepted ablation rate with comparable doses administered to patients with small thyroid residues after total thyroidectomy. It is suggested that the effect of radioiodine treatment may relate inversely to the size of the thyroid remnant. Our findings also are in support of the surgical approach advocating total thyroidectomy for patients contemplating ablation of thyroid residues after surgery for thyroid carcinoma.

Adult↗
PubMed1993

The significance of a positive test of morphine cholescintigraphy in hospitalized patients.

Morphine-augmented radionuclide cholescintigraphy (MC) is a useful adjunctive diagnostic tool for the identification of acute cholecystitis (AC) in patients who are hospitalized and critically ill with occult sepsis. The results of previous studies have demonstrated a reduction in false-positive rates, that is, nonvisualization, from 40 percent with standard radionuclide cholescintigraphy to 5 percent with MC in these high-risk patient groups, with an overall accuracy of 92 percent. This study was performed to determine the significance of a positive test result from MC in patients with occult sepsis. We reviewed the records of all 20 patients at high risk in whom MC was positive during the 35-month period ending 31 May 1992. AC was confirmed by laparotomy in all 16 patients who underwent surgical treatment. There were two patients who recovered with antibiotic therapy alone (considered false-positives) and two additional patients who died without operation or a confirmed diagnosis of AC (excluded from analysis). Thus, in this series, MC was associated with a positive predictive value of 0.89, confirming that it is a valuable adjunct in establishing the diagnosis of AC in patients who are seriously ill and hospitalized with occult sepsis.

Acute Disease↗