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Biomedical subjects

J W May

Publications and source records attributed to J W May.

At least 91 records · Page 5Linked to original sources
PubMed1987

Free and microvascular bone grafting in the irradiated dog mandible.

Microvascular and free rib grafts were placed in 4.5 cm defects in an edentate mandibular body defect 18 to 28 days after completion of 50 Gy of irradiation from a 60Co source. The animals were sacrificed from two to forty weeks postoperatively and evaluated clinically, radiographically, and histologically. There was a marked difference in the alveolar mucosal viability with the two grafts. Mucosal dehiscence was not observed over any of the microvascular grafts, but was present in seven-eighths of the free grafts. Union of the microvascular bone graft to the host bone occurred within six weeks. In contrast, after six weeks the free graft was sequestered in all the animals. An unexpected finding with both types of graft was the marked subperiosteal bone formation. This bone appeared to be derived from the host bed, stabilizing and bridging the defects bilaterally. The results suggest that radiated periosteum may play an important role in osteogenesis.

Animals↗
PubMed1987

Macrodactyly and the epidermal nevus syndrome.

Macrodactyly is an uncommon congenital anomaly that affects the fingers and toes. Speculation as to cause is focused on the association with connective tissue abnormalities, such as neurofibromatosis. We report a highly unusual case of a patient with epidermal nevus syndrome, a specific connective tissue and skeletal disease, who also exhibited bilateral, four finger macrodactyly. Potential causes of linkage between these two specific and unusual syndromes are discussed. Treatment of the epidermal nevus may be nonoperative, differing from the philosophy of aggressive treatment of the similarly appearing premalignant congenital hairy nevus.

Adolescent↗
PubMed1987

Preoperative and postoperative gait analyses of patients undergoing great toe-to-thumb transfer.

Microvascular transfer of the great toe is a reliable method of thumb reconstruction for many patients, but the precise deficit incurred by elective amputation of the great toe has not been fully defined. Twelve patients who had this procedure were evaluated with preoperative and postoperative gait analyses and clinical examinations. The mean age was 29.3 years, with a mean clinical follow-up of 30.3 months, and a comparative follow-up gait study at a mean of 21.1 months postoperatively. Only one patient exhibited a significant motion change postoperatively, which was a reduction in ankle plantar-flexion at weight release of the operated foot (push-off). The average velocity, cadence, step length of the foot that had surgery performed, single and double limb stance times of each foot, and step width did not significantly change. There was only a slight average reduction in stride length at 4.6% (p less than 0.05), which resulted from a decrease in step length of the foot that did not have surgery 7.6% (p less than 0.02). Nine patients had no clinical complaints, two had occasional mild discomfort near the second and third metatarsal heads, and one had intolerance to cold.

Adolescent↗
PubMed1987

Staged use of soft-tissue expansion and lower thoracic advancement flap in breast reconstruction.

A single patient is presented in whom breast reconstruction after mastectomy for breast cancer has been achieved by sequential use of soft-tissue expansion followed by permanent silicone implant placement and thoracic flap advancement to define the inframammary fold. This procedure may play a useful role in patients in whom other, more complex methods of breast reconstruction are not selected or indicated and in particular in patients in whom bilateral silicone implants are utilized.

Adult↗
PubMed1987

Free flaps to preserve below-knee amputation stumps: long-term evaluation.

Five patients with insufficient soft-tissue coverage on below-knee amputation stumps have been treated with free-tissue transfer surgery to preserve a functional below-knee prosthetic level. The flaps employed include one latissimus dorsi myocutaneous flap, two latissimus dorsi muscle-skin graft flaps, one groin flap, and one foot-fillet flap. All five flaps survived; one patient required early venous anastomosis reexploration and revision. The patients have been followed for a mean duration of 5.5 years (range 3 to 8 years). The mean duration to first ambulation with a prosthesis was 3.6 months (range 2 to 7 months). Four of the five patients developed ulcerations on or adjacent to their flaps which required surgical revision. The patients required a mean of 1.28 prosthesis changes annually since surgery. The functional motion (mean active knee motion is 100 degrees) and ligamentous stability of the knee joints were well preserved in all patients. Five patients wear patella tendon-bearing prostheses, with one requiring an additional thigh corset. In two of the patients, nerve anastomoses to their flaps were performed. Both patients developed true cutaneous sensibility, but nevertheless experienced flap ulceration. All the patients are fully ambulatory on their free flaps. Free-tissue transfer can assist in preserving traumatic below-knee amputations so that patients can benefit from the functional advantage of a below-knee prosthetic device.

Adolescent↗
PubMed1987

Plasmid-mediated resistance to gentamicin in Staphylococcus aureus: the involvement of a transposon.

Resistance to gentamicin, tobramycin and kanamycin (GmrTmrKmr) in strains of Staphylococcus aureus isolated from clinical sources in Australia is mediated by a 4.7 kb transposable element, designated Tn4001. A 2.5 kb HindIII fragment which maps symmetrically within Tn4001, and encompasses the aminoglycoside-resistance coding region, has been shown to hybridise with fragments of identical size in HindIII digests of three different GmrTmrKmr plasmids, two of which were self-transmissible, from strains of S. aureus isolated in the USA. Examination by electronmicroscopy of self-annealed molecules of the North American GmrTmrKmr plasmids revealed the presence of stem and loop structures similar to those produced by Tn4001, but with shorter inverted repeats. These results suggest that GmrTmrKmr in strains of S. aureus isolated in the USA is, or once was, transposable, and that transposable elements analogous to Tn4001 may be found in isolates of GmrTmrKmr S. aureus worldwide.

Australia↗
PubMed1987

The reconstruction of defects in the femoral shaft with vascularized transfers of fibular bone.

Seven major reconstructions of the femoral shaft using a vascularized graft of bone from the fibula were performed at the Massachusetts General Hospital from 1981 to 1984. Three patients had a post-traumatic infected non-union; one, extensive osteomyelitis of the femoral shaft; one, a fractured allograft; one, an atrophic non-union associated with radiation therapy; and one, post-traumatic loss of a ten-centimeter segment of bone. Six of the seven patients had a skeletal femoral defect, ranging from seven to fifteen centimeters in length. The average length of fibula that was used for reconstruction was 19.6 centimeters. Primary skeletal union occurred in five of the seven patients. Two patients had healing only at the distal junction and required a conventional bone graft and supplementary internal fixation of the proximal junction. At an average length of follow-up of thirty-four months, all of the patients were able to walk. Only two patients, both of whom had an extreme limb-length discrepancy, required additional support.

Adolescent↗
PubMed1986

Radial nerve cross-finger flap differential nerve contribution in thumb reconstruction.

Six patients with extensive palmar thumb pulp and soft tissue loss were treated with a staged transfer of radial nerve innervated flap tissues from the dorsum of the index finger. They were followed for a mean period of 3 years. This transfer of radial nerve innervated dorsal index finger tissues to the palmar surface of the thumb has been a successful method of innervation restoration. The ultimate sensibility of the reconstructed thumb seems to be a mixture of median and radial nerve sensibility. Sensory testing shows that after transfer, the ulnar side of the flap is more innervated from the radial nerve than the radial side. Our findings suggest that the presence of active sensory axons in the radial nerve innervated flap may play an inhibitory role in direct and/or functional neurotization of the transferred flap.

Adult↗
PubMed1986

End-to-end versus end-to-side microvascular anastomosis patency in experimental venous repairs.

In this experimental study, venous end-to-end and end-to-side microvascular anastomoses in similar and diameter-discrepant vessels were compared. In 50 rats, end-to-end microvascular repair of the divided epigastric vein and end-to-side repair of the epigastric vein into the femoral vein showed 5-day patency rates of 75 and 88 percent, respectively. These data are not statistically different. In 20 rats, microvascular repair of end epigastric to end femoral veins (size discrepant) and end epigastric to side femoral veins showed 5-day patency rates of 50 and 85 percent, respectively. These data are statistically different (p less than 0.05). We conclude from these experimental data that end-to-side venous repairs may be useful in lowering the anastomosis thrombosis rate seen when size-discrepant veins are repaired.

Animals↗
PubMed1986

Thumb reconstruction by free microvascular transfer of an injured index finger.

Thumb reconstruction for amputation at the metacarpal phalangeal level was accomplished by microneurovascular transfer of the contralateral damaged index finger ray, including metacarpal phalangeal joint. This transfer accomplished a successful thumb restoration and removed a cumbersome index finger amputation stump, improving function in both hands. This case emphasizes the merits of spare part transfer in hand reconstructive surgery made possible by microneurovascular techniques.

Amputation Stumps↗
PubMed1986

Seven-digit replantation: digit survival after 39 hours of cold ischemia.

A patient who has undergone successful replantation of seven of eight amputated digits is presented. Survival in the last viable digit was seen 39 hours after amputation with cold ischemia preservation. No graded ischemia-related changes in the digits have been appreciated over 35 months of follow-up.

Adult↗
PubMed1986

Detection of an integrated tetracycline resistance plasmid in the chromosome of methicillin-resistant Staphylococcus aureus.

The majority of multiresistant Staphylococcus aureus strains isolated in Australian hospitals since 1970 carry a chromosomally-encoded minocycline and tetracycline resistance determinant. By using DNA-DNA hybridization, some of these multiresistant strains were shown to possess also a tetracycline resistance plasmid, equivalent to pT181, integrated into a unique site in the chromosome. By relating the hybridization data to the map of pT181, the site of integration on this plasmid was established to be between the genes for replication and tetracycline resistance.

Chromosomes, Bacterial↗
PubMed1986

Characterisation of chloramphenicol resistance plasmids of Staphylococcus aureus and S. epidermidis by restriction enzyme mapping techniques.

Chloramphenicol resistance (Cmr) plasmids pSK2 and pSK5 from Staphylococcus aureus and pSK102 and pSK103 from S. epidermidis have been characterised and detailed restriction endonuclease cleavage maps constructed. TaqI digestion profiles illustrated the identity of pSK5 and pSK102 and also revealed a high degree of similarity between these four Cmr plasmids from Australian staphylococci and three Cmr plasmids from S. aureus strains of geographically unrelated origin. DNA-DNA hybridisation indicated that the chloramphenicol acetyltransferase determinant carried by pSK5/pSK102 could be found on other structurally-distinct Cmr plasmids. The role of S. epidermidis as a reservoir for Cmr plasmids found in S. aureus is discussed.

Base Sequence↗
PubMed1986

Foot reconstruction using free microvascular muscle flaps with skin grafts.

Free muscle flap transfer with skin graft coverage for extensive foot defects can be a successful form of foot reconstruction in well-selected patients who have overall normal foot innervation and deep pressure sensibility. Cutaneous sensibility does not appear to be necessary to maintain a functional or well-healed foot. The major reconstructive goal in plantar foot reconstruction is the restoration of weight-bearing during normal ambulation using regular foot apparel. Based on this reconstructive goal, the authors present their current approach in the reconstruction of extensive defects of the foot using free microvascular muscle flaps with skin grafts.

Adult↗
PubMed1985

Free microvascular muscle flaps with skin graft reconstruction of extensive defects of the foot: a clinical and gait analysis study.

Over the past 4 years at the Massachusetts General Hospital 18 patients have been treated for extensive defects (mean size 130 cm2) of the foot at or below the medial and lateral malleoli. These patients have been treated with free muscle flaps covered with thick split-thickness skin grafts. Full muscle flap survival has been seen in each patient, and all patients are currently ambulatory. A subgroup of nine patients are weight-bearing directly upon their skin grafts covering transferred muscle. All patients are walking without chronic breakdown over a mean follow-up of over 19 months with the exception of a single patient who has had breakdown in a region of redundant improperly tailored muscle flap. None of the skin grafted muscles has significant cutaneous sensibility. Detailed gait analysis of these patients has confirmed the weight-bearing capabilities of free muscle flaps with skin grafts and has proven to be an excellent method of foot reconstruction evaluation. It would appear from this study that cutaneous sensibility may not be necessary for successful reconstruction of the weight-bearing surface of the foot. This method of reconstruction should be considered when local tissues are not suitable for plantar foot reconstruction.

Adolescent↗
PubMed1985

Antibiotic resistance in Staphylococcus aureus isolated at an Australian hospital between 1946 and 1981.

A total of 517 strains of Staphylococcus aureus isolated at a hospital in Melbourne, Australia between 1946 and 1981 was examined for resistance to a range of antimicrobial agents and for the presence of plasmid DNA. The use of mixed-culture transfer and restriction endonuclease analysis showed that the determinants for resistance to penicillin and to the heavy metals were carried by several related plasmids of (15-23) X 10(6) mol. wt, and that tetracycline resistance was encoded on a plasmid of 2.8 X 10(6) mol. wt in strains isolated before 1970. These phenotypes were chromosomally encoded in the majority of strains isolated thereafter. Resistance to chloramphenicol throughout the study period was plasmid-mediated. Of five aminoglycoside-resistance phenotypes, one was plasmid-mediated and three were chromosomally encoded. The remaining phenotype, specifying low-level gentamicin resistance, was found to be located on the chromosome of early isolates, but in later strains was borne by an 18 X 10(6) mol. wt plasmid which also encoded resistance to quaternary ammonium compounds.

Aminoglycosides↗