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Biomedical subjects

G S Gill

Publications and source records attributed to G S Gill.

At least 37 records · Page 2Linked to original sources
PubMed1991

Long-term follow-up evaluation of 1000 consecutive cemented total knee arthroplasties.

This is a report of a retrospective study of 1000 consecutive, cemented total knee arthroplasties performed by one surgeon from January 1976 to August 1989. Eighty-five percent of the patients were available after a mean of 51 months. Using The Knee Society Clinical Rating System, a good to excellent result was found in 95% of the knees; function was good to excellent in 54% of the knees. By using an actuarial method, 94% of the knees can be expected to survive 13 years. A deep venous thrombosis or pulmonary embolus was found in 1.7% and was no less common in the 25% of the patients who received pharmacologic anticoagulation. The mortality rate was 0.4%. The infection rate was 0.7% and did not correlate with intraoperative cultures. There were 14 failures for a variety of reasons, and six unsuccessful knees were revised. Preoperative medical problems did not generally predict the postoperative complications. The average duration of hospitalization during the last five years of the study was 9.7 days. Careful and consistent preoperative, intraoperative, and postoperative care is responsible for the low complication rate. The cemented knee arthroplasty consistently continues to yield good results.

Adult↗
PubMed1990

A novel screening system for yeast strains capable of secreting tissue plasminogen activator.

We have developed a simple screening procedure that allowed us to identify Saccharomyces cerevisiae strains able to secrete human tissue plasminogen activator (tPA) into the culture medium. The screen can be used to isolate more efficient secretor strains and to look for novel tPA analogs. Employing one of these strains to study the effect of glycosylation on secretion, we show that glycosylation in the catalytic domain of tPA plays an important role in folding and/or secretion of the molecule. Removing this glycosylation site resulted in a 3-5-fold reduction in the level of tPA secretion. We anticipate that this system will prove useful in studying yeast secretory pathway as well as structure-function relationships in the tPA molecule.

Biotechnology↗
PubMed1989

Production and secretion of porcine urokinase in Saccharomyces cerevisiae: characterization of the secreted gene product.

The properties of porcine urokinase plasminogen activator (u-PA), produced and secreted by Saccharomyces cerevisiae, were studied to evaluate processing of the enzyme by yeast. Porcine u-PA cDNA was positioned behind the triosephosphate isomerase promoter and the yeast alpha-mating factor secretion signal sequences in a yeast expression vector, pZV125. Greater than 99% of the secreted PA activity was found to be single chain (pro-urokinase). The secreted gene product could be converted to two-chain (tc) with plasmin and then purified to homogeneity on benzamidine sepharose. Plasmin cleavage resulted in the formation of high Mr (HMW) and low Mr moieties representing HMW tc and free catalytic domain, respectively, as detected by N-terminal amino acid sequence analysis. Approximately 60-70% of the secreted activity was found to be associated with hyperglycosylated fractions from G-75 sizing columns. Approximately 30% of the total activity was secreted into the culture medium, where levels of activity approached 200 I.U./ml.

Animals↗
PubMed1988

Precipitation and recovery of proteins from culture supernatants using zinc.

A convenient method for the concentration of proteins from culture supernatants is described. Heterologous gene products expressed and secreted into the culture medium by Saccharomyces cerevisiae, Chinese hamster ovary cells (CHO), and Bacillus subtilis were precipitated out of solution by the addition of millimolar concentrations of zinc chloride. Porcine urokinase secreted by S. cerevisiae, the tissue-type plasminogen activator analog FK2P secreted by CHO cells, and human interleukin-1 beta secreted by B. subtilis were all precipitated by zinc ions. Both urokinase and FK2P were precipitated with as low as 2 mM zinc, with recovery of activity in the precipitate approaching 100%.

Animals↗
PubMed1984

Ecology of leishmaniasis in the south of France. 19. Determination of the hosts of Phlebotomus ariasi Tonnoir, 1921 in the Cévennes by bloodmeal analyses.

Engorged sandflies were collected using 58 CDC light traps set up nightly for 5 weeks at 12 stations in the commune of Roquedur, Gard, France, in the Cévennes focus of leishmaniasis. Of 782 engorged females, 593 were Phlebotomus ariasi, 3 were P. mascittii and 186 were not identified. Using the precipitin ring test and counter-current immuno-electrophoresis, the bloodmeals were tested with antisera to man, leporids, rodents, canids, mustelids, equids, suids, bovids, birds, lizards and amphibia. Of 530 identified bloodmeals, 2 were avian blood, 26 were mixed meals of mammalian blood and 25 were meals taken from unidentified mammals. Of the 477 other sandflies, 211 (44.2%) had fed on canids, 107 (22.4%) on man, 70 (14.7%) on bovids (presumed to be cattle at one station and goats elsewhere), 33 (6.9%) on leporids (probably mostly domesticated rabbits), 26 (5.5%) on mustelids (probably badgers), 17 (3.6%) on horses and 13 (2.7%) on rodents (probably brown rat). The proportions of feeds on different mammals varied according to their availability at each station. When both man and dog were equally available, the dog was preferred. The finding that, away from human habitation, P. ariasi commonly feeds on mustelids suggests the need for a reappraisal of animals of this family as possible reservoirs of leishmaniasis in the Cévennes.

Animals↗
PubMed1981

Mutator bacteriophage D108 and its DNA: an electron microscopic characterization.

Three types of phage particles were observed on CsCl step gradients when D108 was purified from lysates prepared by induction of a prophage. These particle types were identified to be the mature phage, tailless DNA-filled heads, and a form of nucleoprotein aggregates. The nucleoprotein aggregates banded at a density (rho) of greater than 1.6. DNA molecules isolated from mature phage particles were (38.305 +/- 1.226) kilobases (kb) in length. Denaturation and renaturation of D108 DNA resulted in the formation of linear double-stranded molecules with variable-length single-stranded tails at one end. About 30% of the annealed molecules also carried an internal nonhomology, which was shown to be the region called the G-loop in Mu and P1 DNAs. Following the notation used for different regions of denatured, annealed Mu DNA, we measured the lengths of the equivalent D108 DNA regions to be as alpha-D108 = (32.178 +/- 1.370) kb; G-D108 = (3.07 +/- 0.382) kb; beta-D108 = (2.291 +/- 0.306) kb; SE-D108 = (0.966 +/- 0.433) kb. Formation of D108; Mu heteroduplexes disclosed the presence of five nonhomologies, two of which were partial. One of the partial heterologies was in the G-loop region. The largest nonhomology, (1.393 +/- 0.185) kb in size, was near the c end (immunity region) and probably spans the c and the ner genes of Mu. beta-D108 was shown to carry a (0.556 +/- 0.097)-kb insertion close to its right end. A short 100-base-pair region appeared to have been conserved at the ends of D108 and Mu. Occasionally, a 50-to 100-base-pair-long unpaired region was also observed at the left end of D108: Mu heteroduplexes. These sequences were presumably of bacterial DNA. Taken together, our results complement and extend our earlier genetic studies which established that D108 was a mutator phage heteroimmune to Mu with a host range different from Mu's.

Bacteriophage mu↗
PubMed1978

Genetic characterization of Mu-like bacteriophage D108.

Infection of Escherichia coli by bacteriophage D108 was shown to result in the generation of apparently random chromosomal mutations. Approximately 1% of the cells lysogenized by D108, as with Mu, acquired new auxotrophic mutations. D108-induced mutations were nonreverting and were most probably the result of insertion of the D108 genome into regions of genetic function. D108 and Mu shared many similar properties but were heteroimmune and had different host ranges. Lytic infections of Mu lysogens with D108 and D108 lysogens with Mu resulted in 100-fold increases in release of phage with prophage markers over those due to spontaneous induction. Phenotypic mixing was common, with most phage carrying the prophage immunity being packaged in particles with the host range of the superinfecting phage. A fraction of the superinfecting phage genomes were, however, packaged in particles with the prophage-specified host range. Although 10% of the prophage progeny were D108-Mu genetic hybrids, superinfecting phage-induced release of the prophage with reciprocal phenotypic mixing occurred in recA hosts, in which the frequency of D108-Mu genetic hybrids was reduced 100-fold.

Coliphages↗