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Biomedical subjects

J W May

Publications and source records attributed to J W May.

At least 109 records · Page 6Linked to original sources
PubMed1985

Cloning and expression of Staphylococcus aureus plasmid-mediated quaternary ammonium resistance in Escherichia coli.

The Staphylococcus aureus plasmid pSK1 carries Tn4001, a 4.7-kilobase (kb) transposon which specifies resistance to gentamicin, tobramycin, and kanamycin. In addition, pSK1 mediates resistance to trimethoprim and linked resistance to ethidium bromide (Ebr) and to quaternary ammonium compounds (Qar). Restriction endonuclease analysis of pSK1 and a deleted derivative of pSK1 revealed that the gene(s) responsible for Ebr Qar lies within a 5.2-kb HindIII fragment. This fragment has been cloned into the Escherichia coli plasmid vector pBR322, and transformants of an E. coli K-12 strain exhibited Ebr Qar. Subcloning of the 5.2-kb insert, combined with data from electron microscopic analysis of deleted derivatives of pSK1, located the Ebr Qar determinant(s) on a 2.3-kb segment of pSK1 DNA.

Chromosome Mapping↗
PubMed1985

Great toe-to-hand free tissue transfer for thumb reconstruction.

Based upon our experience at the Massachusetts General Hospital, where 32 microneurovascular toe-to-hand transfers have been performed over the past eight years, this method of thumb reconstruction can be quite successful in carefully selected and educated patients.

Adult↗
PubMed1985

Thermocouple probe monitoring for free tissue transfer, replantation, and revascularization procedures.

As the field of microsurgery has expanded over the past decade, the need for a reliable method to monitor the patency of microvascular anastomoses has become increasingly evident. Thermocouple probe monitoring for free tissue transfer, replantation, and revascularization procedures has been done at the Massachusetts General Hospital over the past four years. The authors explain how this method of tissue viability monitoring can be a practical and useful adjunct to clinical surveillance in these complex methods of reconstruction.

Adult↗
PubMed1984

Tn4001: a gentamicin and kanamycin resistance transposon in Staphylococcus aureus.

We describe a 4.5 kilobase transposon, Tn4001, which mediates resistance to gentamicin, tobramycin and kanamycin in Staphylococcus aureus. Originally detected in plasmid pSK1, Tn4001 was shown to undergo rec-independent transposition to the chromosome from this plasmid and from an inserted derivative of the plasmid pII147. Heteroduplexes between plasmids with and without Tn4001 demonstrated a characteristic stem and loop structure with inverted repeats of approx. 1.3 kilobases.

Base Sequence↗
PubMed1984

Source and avoidance of the "nothing dehydrogenase" effect, a spurious band produced during polyacrylamide gel electrophoresis of dehydrogenase enzymes from yeasts.

During a study of the distribution of several NAD-linked dehydrogenase enzymes in various yeasts, in which polyacrylamide gel electrophoresis, followed by activity staining with phenazine methosulfate and a tetrazolium was used, a band was frequently detected, the production of which appeared to be independent of any added substrate (the "nothing dehydrogenase" effect). It has been shown that this effect is caused by alcohol dehydrogenase acting on traces of ethanol inadvertently introduced into the system. Two sources of ethanol were identified. They were (i) the enzyme extracts, which could be freed from ethanol by gel filtration, and (ii) the acrylamide used to prepare the gel, which could be freed from ethanol by recrystallization from ethanol-free chloroform. It is suggested that the use of commercial chloroform (stabilized with ethanol) as a recrystallizing solvent is the source of ethanol contamination in commercial preparations of acrylamide.

Acrylamide↗
PubMed1984

Continuous axillary block through an indwelling Teflon catheter.

Continuous regional anesthesia through a catheter placed in the axillary sheath has been an effective method of brachial plexus neural blockade. This article confirms this observation and demonstrates that continuous axillary block is useful in replantation surgery to provide anesthesia and analgesia in addition to sympathetic blockade for up to 7 days after operation. This anesthetic technique may allow extensive revascularization or replantation procedures to be performed for patients who could not safely tolerate prolonged application of general anesthesia.

Arm Injuries↗
PubMed1984

Thumb reconstruction in the burned hand by advancement pollicization of the second ray remnant.

Reconstruction of 15 thumbs in 14 patients with severe postburn deformity has been carried out by advancement and transferral of the second ray remnant onto the remaining proximal thumb metacarpal stump. This technique combines the advantages of thumb lengthening and pollicization procedures in a single operation and has been a useful method for restoration of single hand prehension in the severely burned mitten hand.

Adolescent↗
PubMed1984

Free latissimus dorsi muscle flap with skin graft for treatment of traumatic chronic bony wounds.

Based on this review of 35 cases of chronic bony wounds, it would appear that the free-muscle flap method of wound closure and nourishment after thorough dead bone debridement is an attractive and successful alternative to local skin flaps, staged skin flaps, or extend skin-muscle flaps in areas where reliable muscle flaps are not available. It would also seem that the latissimus dorsi muscle flap with skin graft is an ideal donor-muscle transfer with features allowing a favorable and contoured surface in the recipient site and minimal aesthetic and functional deformity in the donor site.

Adolescent↗
PubMed1984

Molecular epidemiology of multiresistant Staphylococcus aureus in Australian hospitals.

Antibiotic multiresistant isolates of Staphylococcus aureus from outbreaks of nosocomial infection throughout Australia were found to possess essentially similar patterns of antibiotic resistance. Plasmid DNA profiles from these isolates exhibited a common pattern of large plasmids, of (15-22) X 10(6) mol. wt, associated with resistance to gentamicin, kanamycin and tobramycin, plasmids of 3 X 10(6) mol. wt, mediating resistance to chloramphenicol, and cryptic plasmids of 1 X 10(6) mol. wt. Restriction endonuclease digestion confirmed the presence of related plasmids in isolates from all the hospitals that were surveyed. The homogeneity of these organisms suggests the dissemination of a multiresistant, plasmid-bearing strain of S. aureus, or its derivatives, among geographically-separated hospitals in Australia.

Anti-Bacterial Agents↗
PubMed1984

Antibiotic susceptibilities and plasmid profiles of nosocomial methicillin-resistant Staphylococcus aureus: a retrospective study.

Methicillin-resistant Staphylococcus aureus strains isolated at a single Melbourne Hospital between 1969 and 1981 were examined for susceptibility to a range of antimicrobial agents and for the presence of plasmid DNA. Isolates obtained during 1969 possessed a plasmid of mol. wt 20 X 10(6), encoding heavy metal resistance and penicillinase production, and a plasmid of mol. wt 2.8 X 10(6), mediating tetracycline resistance. In the majority of isolates obtained after 1973, these functions were chromosomally encoded. Before 1980, both high- and low-level chromosomally-encoded gentamicin resistances were encountered, whereas isolates from 1980 and 1981 displayed low-level gentamicin resistance only; the latter phenotype was most commonly mediated by a plasmid of mol. wt 18 X 10(6) that also encoded resistance to tobramycin and kanamycin. Chloramphenicol resistance in strains isolated throughout the period was mediated by one of three plasmids, each of mol. wt c. 3 X 10(6).

Aminoglycosides↗
PubMed1984

Multiple antibiotic resistance in Staphylococcus aureus and Staphylococcus epidermidis: plasmids in strains associated with nosocomial infection.

The plasmid DNA profiles were compared to phenotypically-similar, antibiotic-resistant strains of Staphylococcus aureus and Staphylococcus epidermidis associated with nosocomial infections in a Melbourne hospital. Whereas resistance to gentamicin, tobramycin and kanamycin was encoded by one of 3 plasmids [pSK1, 18 megadalton (Md); pSK4, 22 Md; pSK9, 17 Md] in S. aureus, no similar plasmids were detected in S. epidermidis. Mediated exclusively by the chromosome in S. aureus, tetracycline resistance was encoded either by the chromosome or by a 2.8 Md plasmid in strains of S. epidermidis. The inability to detect common resistance plasmids in strains of S. aureus and S. epidermidis recovered from this outbreak is in contrast to recent observations with staphylococci from other geographic areas; nevertheless, on the basis of restriction endonuclease analyses of 3 Md chloramphenicol resistance plasmids, it is suggested that a common gene pool does exist within isolates of S. aureus and S. epidermidis from Melbourne hospitals.

Aminoglycosides↗
PubMed1983

Analysis of plasmids in nosocomial strains of multiple-antibiotic-resistant Staphylococcus aureus.

Nosocomial infections caused by Staphylococcus aureus strains resistant to methicillin and multiple antibiotics have reached epidemic proportions in Melbourne, Australia, over the past 5 years. Plasmid analysis of representative clinical isolates demonstrated the presence of three classes of plasmid DNA in most strains. Resistance to gentamicin, kanamycin, and tobramycin was usually mediated by an 18-megadalton plasmid but could also be encoded by a related 22-megadalton plasmid. Two distinguishable plasmids of 3 megadaltons each endowed resistance to chloramphenicol, and the third class consisted of small plasmids, each approximately 1 megadalton in size, with no attributable function. An extensive array of resistance determinants, including some which have usually been associated with a plasmid locus, were found to exist on the chromosome. Evidence that resistance to gentamicin, kanamycin, and tobramycin is chromosomally encoded in some clinical isolates suggests that this determinant may have undergone genetic translocation onto the staphylococcal chromosome.

Aminoglycosides↗
PubMed1983

Vascular knee allograft transplantation in a rabbit model.

Using a rabbit model in which vascularized knee autograft transplantation was successful, vascularized knee allograft transplants survived an average of 9 days, as determined by serial bone scan. The longest surviving allograft was one of 3 months. Immunosuppression and irradiation did not significantly increase survival. Both vascularized and nonvascularized allografts elicited a second-set skin graft response but no histologic evidence of rejection. This suggests that joint allografts are clearly immunogenic but do not undergo the same destructive rejection process with a clear end point seen with soft-tissue grafts. Donor vessels did show a classic rejection picture with severe intimal damage presumably predisposing to vessel thrombosis and graft loss. Vascular rejection, therefore, limited joint allograft survival. Immediate vascularization of the allograft with subsequent limited survival does not enhance host revascularization and creeping substitution at 1, 3, or 6 months. These findings do not suggest clinical applicability for vascularized joint allograft transplantation at this time. Future experimental studies should employ genetically defined models.

Animals↗
PubMed1982

Plasmid-mediated antibiotic resistance in methicillin-resistant Staphylococcus aureus.

Strains of methicillin-resistant Staphylococcus aureus (MRSA), isolated from clinical sources in Victoria, were screened for the presence of plasmid DNA. Resistance to gentamicin, kanamycin, and tobramycin was found to reside on an 18-megadalton plasmid, and resistance to chloramphenicol was mediated by a 3-megadalton plasmid. No extra-chromosomal locus was found for resistance to several other antibiotics, including methicillin. Local strains of MRSA differ from their international counterparts by the possession of extensive chromosomal resistance determinants. Together with those encoded on plasmids, these determinants are capable of neutralising almost all available antistaphylococcal antibiotics.

Australia↗