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Biomedical subjects

C J Smith

Publications and source records attributed to C J Smith.

At least 289 records · Page 16Linked to original sources
PubMed1985

Characterization of Bacteroides ovatus plasmid pBI136 and structure of its clindamycin resistance region.

Genetic and physical analyses were used to characterize the Bacteroides ovatus R plasmid pBI136. Results from restriction endonuclease cleavage studies were used to construct a physical map of the plasmid for the enzymes EcoRI, BamHI, ClaI, XbaI, SalI, and SmaI. Based on the sizes of restriction fragments generated in these studies, the plasmid was estimated to be 80.6 kilobase pairs (kb). A 7.2-kb region of the plasmid required for resistance to lincosamide and macrolide (LM) antibiotics was mapped by analysis of spontaneously occurring LM-sensitive deletion derivatives. Hybridization studies showed that this region and an adjoining 2.9-kb EcoRI fragment were responsible for the previously reported homology among Bacteroides plasmids pBF4, pBFTM10, and pBI136. Within this region of homology, 0.5 kb was attributed to a directly repeated sequence thought to bound the LM resistance determinant on pBF4 and pBFTM10. Two pBI136 EcoRI fragments spanning the putative LM resistance region were cloned in Escherichia coli, and heteroduplex analysis of these recombinant plasmids revealed the presence of a 1.2-kb directly repeated sequence. These results suggested that the pBI136 LM resistance determinant resides on an 8.4-kb segment of DNA containing 6.0 kb of intervening DNA sequences bounded by a 1.2-kb directly repeated sequence.

Bacteroides↗
PubMed1985

Development and use of cloning systems for Bacteroides fragilis: cloning of a plasmid-encoded clindamycin resistance determinant.

Chimeric plasmids able to replicate in Bacteroides fragilis or in B. fragilis and Escherichia coli were constructed and used as molecular cloning vectors. The 2.7-kilobase pair (kb) cryptic Bacteroides plasmid pBI143 and the E. coli cloning vector pUC19 were the two replicons used for these constructions. Selection of the plasmid vectors in B. fragilis was made possible by ligation to a restriction fragment bearing the clindamycin resistance (Ccr) determinant from a Bacteroides R plasmid, pBF4;Ccr was not expressed in E. coli. The chimeric plasmids ranged from 5.3 to 7.3 kb in size and contained at least 10 unique restriction enzyme recognition sites suitable for cloning. Transformation of B. fragilis with the chimeric plasmids was dependent upon the source of the DNA; generally 10(5) transformants micrograms-1 of DNA were recovered when plasmid purified from B. fragilis was used. When the source of DNA was E. coli, there was a 1,000-fold decrease in the number of transformants obtained. Two of the shuttle plasmids not containing the pBF4 Ccr determinant were used in an analysis of the transposon-like structure encoding Ccr in the R plasmid pBI136. This gene encoding Ccr was located on a 0.85-kb EcoRI-HaeII fragment and cloned nonselectively in E. coli. Recombinants containing the gene inserted in both orientations at the unique ClaI site within the pBI143 portion of the shuttle plasmids could transform B. fragilis to clindamycin resistance. These results together with previous structural data show that the gene encoding Ccr lies directly adjacent to one of the repeated sequences of the pBI136 transposon-like structure.

Bacteroides fragilis↗
PubMed1985

Polyethylene glycol-facilitated transformation of Bacteroides fragilis with plasmid DNA.

A method for the transformation of Bacteroides fragilis with plasmid DNA was developed by using the clindamycin resistance plasmid pBFTM10 as the source of transforming DNA. The method was technically simple to perform and resulted in an average of 4.2 X 10(3) transformants per microgram of pBFTM10 added. A method for the preparation of frozen competent cells is also described.

Bacteroides fragilis↗
PubMed1985

A role for adenylate cyclase in the subsensitivity to isoproterenol during ontogenesis of the embryonic chick ventricle.

Isoproterenol (ISO) increases contractility and cyclic AMP content in ventricles of embryonic and hatched (H) chicks. A transient decrease in beta agonist sensitivity for both effects (10-fold shift in ISO EC50) is seen in 18-day embryos (18 E) (Pappano and Biegon, 1982). Beta adrenoceptor-coupled adenylate cyclase (AC) and receptor binding were characterized in 14,000 X g ventricular particulates from 10 to 11E, 17 to 19E and 1-week-old chicks (5-6H). The concentration for half-maximal enzyme activation (Kact) for ISO [+100 microM 5'-guanylylimidodiphosphate (Gpp(NH)p)]-stimulated AC is greatest in the 17 to 19E (1.6 microM vs. 0.1-0.2 microM in the 5-6H and 10-11E). Maximal enzyme activity in the presence of ISO + Gpp(NH)p (picomoles of cyclic AMP/20 min X mg of protein), however, is greatest in the 10 to 11E (2018 +/- 80 vs. 1020 +/- 80 and 1120 +/- 60 in the 17 to 18E and 5 to 6H, respectively). The Kact values for NaF and Gpp(NH)p are the same for all three ages (2.4 mM and 8 microM, respectively), whereas maximal activity with these effectors of the regulatory and catalytic protein-dependent AC decreases with increasing age. Neither the Kact nor maximal activity of catalytic AC, assessed with MnCl2 and forskolin, changes with age. The respective Kact values for MnCl2 and forskolin are 0.3 mM and 4 microM.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1984

Evaluation of AFP glycosylation heterogeneity in cancer patients with AFP-producing tumors.

It has been postulated that analysis of alpha-fetoprotein (AFP) glycosylation heterogeneity in cancer patients whose AFP levels are elevated (e.g., non-seminomatous germ cell tumors, ovarian germ cell tumors and primary hepatocellular carcinoma) might provide useful clinical information. We undertook a study to determine whether scrutiny of AFP glycosylation heterogeneity in patients with non-seminomatous germ cell tumors would provide information useful in diagnosis, staging, prognosis, or monitoring for recurrence of disease following therapy. While an analysis of AFP glycosylation heterogeneity using Concanavalin A lectin chromatography did not provide useful information in regard to staging or prognosis, it does supply unique information useful in discriminating between benign liver dysfunction (e.g. alcoholic hepatitis, chemotherapy-related liver damage) and that due to nonsemininomatous germ cell tumors. It was also concluded that an analysis of Concanavalin A binding patterns is not sufficient to discriminate between recurrent non-seminomatous germ cell tumor and primary hepatocellular carcinoma in patients with elevated serum AFP.

Adult↗
PubMed1984

Analysis of the Escherichia coli proBA locus by DNA and protein sequencing.

A 2.9 kb DNA fragment carrying the Escherichia coli proBA region, which encodes the first two enzymes of the proline biosynthetic pathway, was subcloned onto an expression plasmid carrying both the bacteriophage lambda PL promoter (lambda PL) and the lambda gene encoding a thermolabile cI repressor protein (cI857). Derepression of the lambda PL promoter by thermal inactivation of the cI857 repressor protein resulted in the simultaneous overproduction of the proB (gamma-glutamyl kinase) and proA (gamma-glutamyl phosphate reductase) gene products. Nucleotide sequence analysis of the proBA locus allowed gene assignments consistent with the NH2 and COOH-terminal analyses and amino acid compositions of homogeneous preparations of the proB and proA proteins. The contiguous nature of the proB and proA genes suggests that the two genes constitute an operon in which proB precedes proA.

Aldehyde Oxidoreductases↗
PubMed1984

Depigmenting action of hydroquinone depends on disruption of fundamental cell processes.

The effect of the skin-depigmenting agent hydroquinone (HQ) on 2 melanotic and 3 nonmelanotic cell lines was studied. Significant differences in its effect on DNA and RNA synthesis were observed between cell lines. HQ caused inhibition of cellular metabolism in all cells tested, but the dose that caused 50% inhibition of tritiated thymidine incorporation was approximately 30 times lower for melanotic cells. Tritiated uridine incorporation was found to be 85 times more sensitive to HQ in the melanotic cells. These results suggest that HQ exerts its depigmenting effect by selective action on melanocyte metabolism rather than a specific effect on melanin synthesis. Further, the effects of UV irradiation on this system were investigated and found to be negligible, in spite of the stimulation of in vivo melanin synthesis by UV radiation.

Animals↗
PubMed1984

The effects of three differing anaesthetics on the immune response.

A clinical study was undertaken to investigate changes in the immune response in patients undergoing three differing anaesthetic techniques for inguinal hernia repair. No significant differences between anaesthetic groups were demonstrated in the haematological parameters. The value of mitogen stimulation tests was questioned in the clinical setting. The migratory component of neutrophil function was shown to be preserved following conduction anaesthesia compared to the other anaesthetic groups and its possible advantage noted.

Adult↗
PubMed1984

Purification and characteristics of a gamma-glutamyl kinase involved in Escherichia coli proline biosynthesis.

gamma-Glutamyl kinase, the first enzyme of the proline biosynthetic pathway, was purified to homogeneity from an Escherichia coli strain resistant to the proline analog 3,4-dehydroproline. The enzyme had a native molecular weight of 236,000 and was apparently comprised of six identical 40,000-dalton subunits. Enzymatic activity of the protein was detectable only in assays containing highly purified gamma-glutamyl phosphate reductase, the second enzyme of the proline pathway. Plots of gamma-glutamyl kinase activity as a function of glutamate concentration were sigmoidal, with a half-saturation value for glutamate of 33 mM, whereas plots of enzyme activity as a function of ATP concentration displayed typical Michaelis-Menten kinetics with a Km for ATP of 4 X 10(-4) M. Enzyme activity was insensitive to the glutamate analog L-methionine-DL-sulfoximine, but ADP was a potent competitive inhibitor. Characteristics of the enzyme were compared with those of a gamma-glutamyl kinase partially purified from a 3,4-dehydroproline-sensitive E. coli. These results indicated that the only major difference was that the enzyme from the 3,4-dehydroproline-resistant strain was 100-fold less sensitive to feedback inhibition by proline.

Escherichia coli↗
PubMed1984

Large transmissible clindamycin resistance plasmid in Bacteroides ovatus.

Bacteroides ovatus IB106 contained two plasmids, pBI106 (46 kilobases) and pBI136 (82 kilobases). Transmissible clindamycin-erythromycin resistance (Ccr) was mediated by pBI136 , whose Ccr determinant was closely related to the determinant on the Bacteroides R plasmids pBF4 and pBFTM10 . Hybridization studies showed that pBI106 was not involved in Ccr transfer, but it shared extensive homology to pBF4 with the exception of the pBF4 region implicated in Ccr.

Bacteroides↗
PubMed1984

Geographic patterns of funding for community mental health centers.

The author examines geographic patterns of funding for community mental health centers (CMHCs) between 1965 and 1980. Using data from the National Institute of Mental Health, he discusses the evolution of CMHC funding patterns and correlates state per capita funding within three time periods with indexes of social and financial well-being and innovativeness. The author concludes that although redistributing resources from richer to poorer states was not a major aim of the community mental health centers legislation, CMHC funding both nationally and within states was at least moderately redistributive.

Catchment Area, Health↗
PubMed1983

The effect of long-term high-fibre diets in diabetic outpatients.

Diets containing large amounts of dietary fibre have been shown to be beneficial in improving diabetic control. We investigated the practical aspects of administering a high-fibre diet to diabetic outpatients in Cape Town, using readily available, low-cost foodstuffs with a high dietary fibre content. Ten patients were followed up over a period of 9 months, for 3 months of which a high-fibre diet was prescribed. Although only 3 patients approached the projected dietary fibre intake, significant negative correlations were found between the mean plasma glucose changes and the dietary fibre increments (r = 0,704; P less than 0,05) and between the mean serum triglyceride changes and the dietary fibre increments (r = -0,741; P less than 0,05). These findings suggest that, were it not for poor dietary compliance, a high-fibre diet might result in significant improvement in diabetic control, and that education and motivation are of prime importance when making major changes to patients' eating habits.

Adult↗
PubMed1983

Relative effectiveness of various yeasts, Candida spp. and Torulopsis glabrata, for inducing palatal infection in the Wistar rat.

Candida albicans serotypes A and B, Candida tropicalis and Torulopsis glabrata were tested for their ability to produce palatal candidosis in the rat. C. albicans serotype A consistently produced palatal candidosis whereas serotype B did so in only two of five animals tested, indicating a difference in pathogenicity of the two serotypes. C. tropicalis and T. glabrata did not induce changes under the conditions tested and their colonization of palatal mucosa in commensal form was dependent on the presence of an acrylic plate.

Animals↗
PubMed1983

Multisystem sarcoid presenting with gingival hyperplasia.

A case is reported in which granulomatous gingival hyperplasia was the presenting feature of generalised sarcoidosis. Treatment with oral prednisolone resulted in resolution of both the granulomatous lesion of the gums, and of proteinuria. It is pointed out that although on histological examination sarcoidosis in this site cannot be distinguished from Crohn's disease, the clinical appearance in this patient (and the only similar case in the literature) was quite different from that seen in oral Crohn's disease.

Adolescent↗
PubMed1983

Exposure to ethanol during pregnancy in mice: potential importance of dose for the development of tolerance in offspring.

CD-1 albino mice were given Portagen-10 percent ethanol (ETOH) or isocaloric Portagen-sucrose during pregnancy to determine if tolerance developed in utero and to describe the temporal pattern of its decline postnatally. ETOH mothers did not significantly increase their consumption of ETOH but gained in body weight during pregnancy, showed no signs in the open field of withdrawal from ETOH shortly after delivery and showed less pup-caring behavior than pair-fed controls (PFC). Among offspring 1, 3, 10, 25 and 60 days old, only 25-day old ETOH pups metabolized and cleared an anesthetic dose of ETOH more efficiently than PFC animals, suggesting the absence of Dispositional Tolerance in the other animals. PFC offspring 10 days old took significantly longer to lose the righting reflex than their ETOH counterparts following the anesthetic dose of ETOH, the difference being opposite that which would suggest the occurrence of Adaptive Tolerance. Data are discussed primarily in terms of decreases in dose of ETOH to which mothers and fetuses were exposed during pregnancy.

Alcohol Drinking↗