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Biomedical subjects

J Sampson

Publications and source records attributed to J Sampson.

At least 19 recordsLinked to original sources
PubMed1992

Typing of methicillin-resistant Staphylococcus aureus with an M13 repeat probe.

A bacteriophage M13 tandem repeat has been used to probe EcoRI digested genomic DNA of methicillin-resistant Staphylococcus aureus (MRSA). The patterns generated were found to be useful in typing MRSA and generally confirmed the relationships that had previously been recognized in other studies based on antimicrobial resistance and plasmid profiles. The epidemic MRSA of London hospitals (EMRSA) and the majority of the epidemic MRSA of eastern Australian hospitals (EA MRSA) gave the same pattern. However, two isolates previously classified as EA MRSA gave a different pattern and a third another pattern. One isolate from Dublin, two isolates from Nuneaton and two isolates from Singapore gave the same pattern as the two EA MRSA. With the exception of the early or classic MRSA all the other isolates examined gave their own distinctive patterns. With one exception the classic MRSA belonged to a separate group. The exception was of particular interest because it gave the same pattern as the majority of the EA MRSA. This suggests that there may be an evolutionary relationship between some of the classic MRSA and the EMRSA of London and the EA MRSA of Australia.

Bacterial Typing Techniques↗
PubMed1991

Recent linkage studies in tuberous sclerosis. Chromosome 9 markers.

After our initial reports 3-5 supporting a locus for tuberous sclerosis (TSC) on 9q, linkage analysis was undertaken in eight large multigeneration TSC families using nine polymorphic markers. Six of the markers were from the distal long arm of chromosome 9 and three from the long arm of chromosome 11. The data as a whole supported a TSC locus on distal 9q, the peak lod score on multipoint analysis being 3.77 6 cM proximal to the Abelson oncogene locus (ABL). However, analysis of 2-point lod scores using the HOMOG programs revealed significant evidence for genetic heterogeneity (p = 0.01), tight linkage to ABL being highly unlikely in one family. After exclusion of the unlinked family multipoint, analysis gave a peak lod score of 6.1 in the vicinity of ABL. The family unlinked to ABL showed no recombinants with two chromosome 11 probes, but it was too small to provide significant evidence for linkage. Genetic heterogeneity in TSC as demonstrated by this study will complicate efforts to clone the genes by reverse genetics and will severely hamper the use of linked probes for carrier detection and prenatal diagnosis.

Chromosomes, Human, Pair 9↗
PubMed1991

Von Hippel-Lindau disease: a genetic study.

Genetic aspects of von Hippel-Lindau (VHL) disease were studied in familial and isolated cases. Complex segregation analysis with pointers was performed in 38 kindreds with two or more affected members. Dominant inheritance with almost complete penetrance in the highest age classes (0.96 at 51 to 60 and 0.99 at 61 to 70 years) was confirmed and there was no evidence of heterogeneity between families ascertained through complete and incomplete selection. The point prevalence of heterozygotes in East Anglia was 1.89/100,000 (1/53,000) persons with an estimated birth incidence of 2.73/100,000 (1/36,000) live births. Reproductive fitness was 0.83. Direct and indirect estimates of the mutation rate were 4.4 (95% CI 0.9 to 7.9) x 10(-6)/gene/generation and 2.32 x 10(-6)/gene/generation respectively. There was no significant association between parental age or birth order and new mutations for VHL disease.

Adult↗
PubMed1990

Regional procurement and export of hepatic allografts for transplantation.

A team dedicated to hepatic procurement exclusively for export to distant centers was established at The Mount Sinai Hospital in New York. Between January 1987 and March 1988, 20 livers were retrieved and sent to five institutions in the U.S. and Canada for implantation. These procedures were carried out in concert with local cardiac and renal procurement teams; 12 hearts and 34 kidneys were used from these 20 donors. Functional results of both the livers and the other organs were in line with nationally reported standards. The multi-organ procurement procedure was streamlined as a result of the coordination which developed between the teams. Savings in time and travel expense by skilled personnel were realized; in five cases no alternative hepatic procurement team was available. With the ability to preserve livers for increasingly long periods, this type of program will assume greater importance in the future.

Humans↗
PubMed1986

Ovarian metastasis from colorectal cancer.

Controversies exist regarding the surgical treatment of the ovaries in women with primary colorectal cancer. A review of the authors' experience and the surgical literature reveals an incidence of ovarian metastases from colorectal cancer of approximately 6 percent. This problem may occur somewhat more frequently in premenopausal women. Resection of the ovaries at the time of colectomy is unlikely to affect survival. Removal of the ovaries at the time of bowel resection will prevent repeat laparotomy to resect an ovarian mass in approximately 2 percent of women with large bowel cancer. Oophorectomy should be performed in all postmenopausal females at the time of primary resection. Oophorectomy should be performed in premenopausal women if any gross abnormality of the ovary is detected or if peritoneal implants are seen at the time of primary resection.

Adenocarcinoma↗
PubMed1985

Quantification of DNA uptake by Dictyostelium discoideum amoebae and the stability of the DNA during growth and development.

We have developed a simple and accurate method to determine the amount of intact plasmid DNA taken up and retained by Dictyostelium discoideum amoebae during various transformation protocols. We have used this method to compare the efficiency of three different methods for introducing foreign DNA into D. discoideum amoebae. Both a calcium phosphate and a spheroplast fusion procedure gave good uptake, but no intracellular plasmid DNA was detectable after calcium chloride treatment. The exogenous DNA was rapidly lost after transformation but was 20-fold more stable during starvation rather than growth conditions, suggesting a possible approach to improving transformation efficiency. No transient expression of neomycin phosphotransferase activity of any of the heterologous animal or plant promoters used could be detected using a sensitive gel assay procedure.

DNA, Fungal↗
PubMed1985

Evaluation of a modified enzyme immunoassay for Neisseria gonorrhoeae in high- and low-risk females.

A recently modified commercial enzyme immunoassay (Gonozyme; Abbott Laboratories, North Chicago, IL) for Neisseria gonorrhoeae antigens was compared with bacteriological culture for diagnostic sensitivity, specificity, and predictive value. A total of 480 specimens were tested by both methods; 355 from females attending a sexually transmitted disease clinic ("high-risk") and 125 from female Family Planning clients ("low-risk"). Sensitivity and specificity of enzyme immunoassay for sexually transmitted disease clinic specimens were 79.7 and 97.9%, respectively (55 positive, 280 negative, 6 false positive, 14 false negative). In the low-risk population, sensitivity and specificity were 100 and 97.5%, respectively (3 positive, 119 negative, 3 false positive, 0 false negative). Despite modification, sensitivity of the method remains low for our sexually transmitted disease clinic population, but the test may have applicability for preliminary screening in low-prevalence settings.

Antigens, Bacterial↗
PubMed1983

The effects of inhibition of protein glycosylation on the aggregation of Dictyostelium discoideum.

At concentrations greater than 10 micrograms ml-1 tunicamycin inhibited the incorporation of [3H]mannose into glycoproteins during the early phase of development in Dictyostelium discoideum, however, total protein synthesis was unaffected. Tunicamycin also interfered with the normal process of aggregation. In its presence small aggregates were observed at the time of normal aggregation, but amoebae failed to aggregate completely and subsequent development was inhibited. Inhibition of normal aggregation by tunicamycin was found to be reversible. The appearance of cell-associated and secreted cyclic AMP phosphodiesterase and cell-surface contact sites A was prevented by tunicamycin but cell surface cyclic AMP receptor activity developed normally in its presence. Tunicamycin also prevented amoebae from acquiring the ability to chemotact toward cyclic AMP. Addition of exogenous cyclic AMP phosphodiesterase restored the ability of amoebae to chemotact toward cyclic AMP in the presence of tunicamycin. Our data suggest that the primary block in aggregation caused by tunicamycin results from the inhibition of expression of active cyclic AMP phosphodiesterase.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1982

The role of Tennessee antigen in the diagnosis of gastrointestinal malignancy.

Tennessee antigen (TAG) is a glycoprotein which has been extracted from adenocarcinoma of the colon. It is one of the numerous tumour associated antigens which has been developed and there is evidence that it differs considerably from carcino-embryonic antigen (CEA) preparations. A commercial kit using a haemagglutination inhibition assay is available and its ability to discriminate between benign and malignant conditions of the gastrointestinal tract has been studied, using 7.7 units/ml as the upper limit of normal. With upper gastrointestinal disease, discrimination is comparable to that achieved with TAG by other workers and also to that achieved with CEA. For gastric carcinoma TAG has a sensitivity of 71% and a specificity of 77%. With lower gastrointestinal tract disease discrimination was poor, TAG having a sensitivity of 76% but a specificity of 44% for colorectal carcinoma. Discrimination between pancreatic carcinoma and chronic pancreatitis was poor, TAG having a sensitivity of 100% for carcinoma and a specificity of 22%.

Adenocarcinoma↗
PubMed1980

Gastroenteritis due to rotavirus in an isolated Pacific island group: an epidemic of 3,439 cases.

In the spring of 1964, 3,439 cases of acute gastroenteritis were reported from Truk District, an island group in the mid-Pacific. The causative agent was not identified in laboratory studies performed in that year. Retrospective serologic studies 15 years later with the complement fixation test and the enzyme-linked immunosorbent assay provided serologic evidence that this outbreak was caused by the human rotavirus that was first isolated in 1973.

Adolescent↗
PubMed1978

Trimethoprim/sulfamethoxazole and renal function in transplant patients.

Twenty-two patients with functioning renal allografts took part in a double-blind crossover trial during which placebo, sulfamethoxazole, and trimethoprim/sulfamethoxazole were given for periods of 14 days. The patients were divided into 2 groups. The first group consisting of 12 patients had serum creatinine levels less than 0.18 mmol/L and the second group of 10 patients had serum creatinine levels between 0.18 mmol/L and 0.35 mmol/L. Renal function at the end of each period was assessed by clearance of inulin (CIn), p-aminohippurate (CPAH) and endogenous creatinine (CCr). The second group also had a pitressin concentration test as a measure of distal tubule function. There was no change in inulin or creatinine clearance or in maximum concentration after pitressin in any of the patients in any of the phases. In the first group there was an increase in PAH clearance during the sulfonamide and trimethroprim/sulfamethoxazole phases. This change was not seen in the second group of patients with significantly impaired renal function.

Adult↗
PubMed1978

Effects of BUdR on developmental functions of Dictyostelium discoideum.

The development of Dictyostelium discoideum cells, as measured by spore yield, is somewhat more sensitive to the presence of BUdR during vegetative growth than is growth itself. Observations on the development of control and BUdR-grown cells, their protein labelling patterns and assays of 4 developmentally regulated proteins all reveal a consistent picture. BUdR appears to block spore formation by partially inhibiting several or many different earlier events during development. The relative sensitivity of development compared to growth to inhibition by the drug may be a consequence of the nature of the developmental process rather than of some unique specificity of the inhibitor.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1977

Developmentally regulated cyclic AMP-dependent protein kinases in Dictyostelium discoideum.

Two apparently distinct species of cyclic AMP-dependent protein kinase appear during the first 1-2 hr of development in Dictyostelium discoideum; no such activity can be detected in vegetative cell extracts. These two kinases are similar in properties to the type I and II cyclic AMP-dependent protein kinases found in a number of mammalian tissues. Their time of appearance supports the idea that one or both mediate the effects of cyclic AMP on gene expression early in Dictyostelium development.

Cell Extracts↗