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Biomedical subjects

A Wyman

Publications and source records attributed to A Wyman.

36 records · Page 2Linked to original sources
PubMed1989

Intercostal blockade and pulmonary function after cholecystectomy.

Sixty-six patients undergoing cholecystectomy were randomly allocated to receive either intercostal blockade with bupivacaine supplemented with papaveretum or papaveretum alone for postoperative analgesia. Both groups were similar regarding distribution of sex, age, and weight. These two groups were compared. Patients who did not have intercostal blockade required postoperative analgesia sooner. There was no significant difference, however, in the total consumption of papaveretum. Both groups experienced similar degrees of pain, and there were no differences in postoperative pulmonary function. We conclude that although single intercostal blockade is an effective analgesic, it does not improve pain relief and does not improve pulmonary function after cholecystectomy when compared with a regimen of on-demand, intramuscularly administered papaveretum.

Analgesia↗
PubMed1987

What time of day should a urethral catheter be removed?

Patients who had undergone bladder neck surgery were randomized to having their urethral catheters removed either early in the morning or late at night. There was no difference in the incidence of urinary retention between these two groups of patients. However, patients who presented with acute urinary retention had a higher incidence of postoperative urinary retention. This study suggests that a urethral catheter may be safely removed in the evening without increasing the risk of urinary retention. There also seems to be no greater chance of the patient having to be recatheterized at an unsocial hour.

Aged↗
PubMed1986

Isolation of molecular probes associated with the chromosome 15 instability in the Prader-Willi syndrome.

Flow cytometry and recombinant DNA techniques have been used to obtain reagents for a molecular analysis of the Prader-Willi syndrome (PWS). HindIII total-digest libraries were prepared in lambda phage Charon 21A from flow-sorted inverted duplicated no. 15 human chromosomes and propagated on recombination-proficient (LE392) and recBC-, sbcB- (DB1257) bacteria. Twelve distinct chromosome 15-specific probes have been isolated. Eight localized to the region 15q11----13. Four of these eight sublocalized to band 15q11.2 and are shown to be deleted in DNA of one of two patients examined with the PWS. Heteroduplex analysis of two of these clones, which grew on DB1257 but not on LE392, revealed stem-loop structures in the inserts, indicative of inverted, repeated DNA elements. Such DNA repeats might account for some of the cloning instability of DNA segments from proximal 15q. Analysis of the genetic and physical instability associated with the repeated sequences we have isolated from band 15q11.2 may elucidate the molecular basis for the instability of this chromosomal region in patients with the PWS or other diseases associated with chromosomal abnormalities in the proximal long arm of human chromosome 15.

Chromosome Deletion↗
PubMed1982

Single-copy sequence hybridizes to polymorphic and homologous loci on human X and Y chromosomes.

Use of a 4.5-kilobase-pair (kb) segment of single-copy DNA from a human genomic library as a hybridization probe of genomic human DNAs revealed allelic Taq I restriction fragments 10.6, 11.8, and 14.6 kb long. Among 12 unrelated individuals, all 6 males exhibited the 14.6-kb fragment in addition to one of the other fragments. Three of the females displayed 10.6- and 11.8-kb fragments, and the other three displayed only one fragment length; none had the 14.6-kb fragment. Hybridization of this probe to Taq I-digested DNAs from human-rodent hybrid cell lines (which have partial complements of human chromosomes) demonstrated segregation of the 14.6-kb fragment with the human Y chromosome and segregation of the 10.6- and 11.8-kb fragments with the human X chromosome. Furthermore, hybridization of this probe to Taq I-digested DNAs from 48 members of a single kindred revealed Y-linked inheritance of the 14.6-kb fragment and X-linked inheritance of the 10.6- and 11.8-kb fragments. These experiments demonstrate homology between single-copy sequences on the human X and Y chromosomes.

Alleles↗
PubMed1975

Purification and properties of homoserine transacetylase from Bacillus polymyxa.

Homoserine transacetylase (EC 2.3.1.31), the first enzyme of methionine biosynthesis, has been purified to near homogeneity from extracts of a methionine auxotroph of Bacillus polymyxa. The enzyme is subject to rapid irreversible inactivation. Its half-life at 0 degrees is 15 min and much less at higher temperatures, but ethylene glycol affords some protection. In addition, Zn2+ reversibly inhibits the enzyme with a K-I of 3 muM. The enzyme has a molecular weight of about 40,000 and consists of a single polypeptide chain. Besides catalyzing the acetyl transfer from acetyl-CoA to L-homoserine, homoserine transacetylase promotes a homoserine-O-acetylhomoserine exchange reaction in the absence of CoA, suggesting the formation of an acetyl-enzyme intermediate. The results of kinetic studies are consistent with a ping-pong mechanism. Homoserine transacetylase is subject to multivalent feedback inhibition by L-methionine and S-adenosylmethionine. Analysis of the inhibition data and specificity studies suggest that the inhibitors bind to separate sites on the enzyme which are distinct from the active site. Inhibition is competitive with respect to both substrates, and the saturation curves for the inhibitors, as well as substrate saturation curves in the absence or presence of the inhibitors, are hyperbolic. The absence of cooperativity is, in fact, a property which would be expected in a monomeric allosteric enzyme such as homoserine transacetylase.

Acetyl Coenzyme A↗
PubMed1975

Regulation of homoserine transacetylase in whole cells of Bacillus polymyxa.

The levels of homoserine transacetylase (EC 2.3.1.31) in Bacillus polymyxa grown in minimal medium can vary over a 40-fold range, depending on whether methionine limits growth or is present in excess. This suggests that the synthesis of the enzyme is under control by methionine or one of its metabolites. The stability of homoserine transacetylase in growing cells was measured after repression of further synthesis by the addition of methionine. At 30 degrees, the enzyme was stable for 2 hours, whereas at 37 degrees it decayed with a half-life of 40 min. This contrasts with the striking instability in cell-free extracts described in the preceding paper (Wyman, A., and Paulus, H. (1975) J. Biol. Chem. 250, 3897-3903). The properties of homoserine transacetylase were also studied in cells of B. polymyxa that had been made permeable to small molecules by treatment with toluene. They differed in two important respects from those of the enzyme in cell-free extracts described in the preceding paper: the enzyme was relatively stable, with a half-life of 15 min at 37 degrees, and responded in a sigmoid manner to increasing concentrations of the inhibitors L-methionine and S-adenosylmethionine. These observations suggest that homoserine transacetylase is an oligomeric protein within the bacterial cell but dissociates into monomers in cell-free extracts. When B. polymyxa was transferred at 39 degrees from a rich medium to one without amino acids, growth resumed only very slowly. The growth lag after shift-down was not observed at 37 degrees or in the presence of methionine or cystathionine. This phenomenon appears to be due to a need for derepression of homoserine transacetylase upon shift-down which is thwarted at 39 degrees by the rapid thermal inactivation of the enzyme. A possible physiological function of the striking thermolability of the first enzyme in methionine biosynthesis is discussed.

Acetyltransferases↗
PubMedDate not supplied

Parameters for and safety of contact Nd:YAG laser irradiation of early gastric cancer: an in vitro study.

Early gastric cancers have been treated by endoscopic contact Nd:YAG laser irradiation. The extent of thermal damage produced by this laser system has been inadequately investigated. In an in vitro study we have shown that contact laser probes produce consistent and reproducible thermal lesions in the human stomach wall. Contact laser energies of 40 to 60 joules are optimal for the ablation of early gastric cancer. Energies greater than 90 joules are associated with a high incidence of gastric perforation. Contact laser probes may have advantages over non-contact laser techniques for the endoscopic treatment of early gastric cancer in patients who are unfit for major surgery.

Adenocarcinoma↗
PubMedDate not supplied

Surgery for gastric cancer.

Radical dissection for gastric cancer is not widely practiced in the West. This paper reviews the evidence in support of lymphadenectomy and the techniques of radical resection as practiced by Japanese surgeons. We believe the published results support increased use of radical surgery in the treatment of gastric cancer and would recommend further adoption of this technique as there is minimal associated morbidity.

Gastrectomy↗