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Biomedical subjects

J W May

Publications and source records attributed to J W May.

At least 73 records · Page 4Linked to original sources
PubMed1989

Elective cross-hand transfer: a case report with a five-year follow-up.

The elective free microvascular cross-hand transfer of the right hand to the left distal carpus was successfully performed in a 35-year old professional photographer. Traumatic loss of the left hand with preservation of a useful thumb and concomitant right upper extremity injury leaving the right hand with an amputated thumb, but paralyzed and insensate from a brachial plexus palsy 5 years before transfer, set the stage for such a reconstruction. Multiple immediate tendon transfers and primary nerve grafting provided for finger flexion and extension plus functional sensibility in this first reported case of an elective cross-hand microvascular transfer. Five years follow-up demonstrates useful and powerful flexion, and functional extension of digits in the reconstructed left hand and right upper extremity function has been improved with a below-elbow prosthesis.

Adult↗
PubMed1989

Correlation of postoperative bone scintigraphy with healing of vascularized fibula transfer: a clinical study.

This study examines the usefulness and reliability of bone scintigraphy in correlation with radiological and clinical evidence of bone healing in 15 patients who underwent microvascular transfer of the fibula. All patients were followed for a minimum of 18 months postoperatively. Technetium-99 methylene diphosphonate bone scans and the most recent radiographs were blindly rereviewed. Bone scintigraphic results were characterized as (1) clearly positive (i.e., excellent visualization of the fibula), (2) clearly negative (i.e., no evidence of tracer uptake in the fibula), or (3) indeterminate (i.e., artifact present as a result of metallic or soft tissue interference). Bone radiographs were classified into three typical patterns: (1) complete bony union and graft hypertrophy, (2) incomplete union (either distal or proximal) requiring a second procedure), and (3) nonunion, with increased proximal and distal lucency (with or without pathological fracture) and loss of graft definition. Eleven patients had positive scintigraphic scans postoperatively. In 8 no subsequent procedure was necessary; 2 patients required additional bone grafts to augment the osseous reconstruction; viable fibulas were seen at reoperation. One patient with a positive scan showed decreased graft definition at four months followed by autograft fracture. Three patients had indeterminate scans, 2 of whom evidenced uncomplicated clinical and radiological union. One patient had a clearly negative scan and ultimately tibia-fibula synostosis was required to attain stability. Bone scintigraphy appears to correlate with survival, but not necessarily union, of a vascularized fibula autograft. Additional monitoring techniques should be used in combination with a one-time bone scan to both monitor the patency of the microanastomoses and to prioritize the orthopedic management of the patient.

Arteries↗
PubMed1989

Historical review and present status of free fat graft autotransplantation in plastic and reconstructive surgery.

Free fat graft autotransplantation for soft-tissue replacement has been a neglected subject in recent years. In a review of the literature, investigations of the various uses of free fat autotransplantation in animals and humans provide an understanding of the problems associated with the use of fat as a free graft. Results of free fat autotransplantation were found to be quite unpredictable, with wide variations in the resulting bulk of the graft. Microscopic studies of this behavior led to controversy as to whether the graft ultimately was made of surviving graft adipocytes (cell survival theory) or host adipocytes (host replacement theory). Studies revealed a "fibroblast-like" mesenchymal cell within adipose tissue that was believed to be an immature adipocyte precursor or preadipocyte. Further characterization of the preadipocyte and its complete differentiation was accomplished using tissue-culture techniques. These investigations provide evidence of the dynamic nature of adipose tissue that strongly supports the cell survival theory and gives explanation to the unpredictable behavior of free fat autografts. Many conditions treated by plastic surgeons require soft-tissue augmentation. Autogenous adipose tissue is the most appropriate and natural replacement material. With new culturing techniques, preadipocytes in a single cell suspension may provide an injectable soft-tissue replacement. This subject appears ripe for investigation.

Adipose Tissue↗
PubMed1989

Effect of the timing of tourniquet release on postoperative hematoma formation: an experimental animal study.

There is a controversy over when to release a pneumatic tourniquet after completing a hand surgical procedure. To study this controversy, we performed a standardized operation with tourniquet inflow occlusion on both lower legs of a series of rabbits. Total tourniquet time and the procedure performed, including intraoperative Bovie electrocautery of actual and potential bleeding points identified with 2.5 X loupe magnification, were identical on the two sides, except for the method of tourniquet release. On one leg, the tourniquet was released and all new bleeding points were controlled prior to wound closure. On the other leg, the tourniquet was released after the wound had been closed and dressed. Animals were injected with technetium-99m-labeled red blood cells and scanned to measure hematoma formation. Qualitatively, we observed more label in the leg whose tourniquet was released after wound closure in 17 of the 20 animals (p less than 0.005). Quantitatively, we also measured more mean label in the leg whose tourniquet was released after the wound was closed (p less than 0.001). Tourniquet release after wound closure was associated with greater hematoma formation.

Animals↗
PubMed1989

Microvascular surgical experimental thrombosis model: rationale and design.

The rationale for the design of surgical models of microvascular thrombosis is discussed, and a new model, the arterial inversion graft (AIG), is described and evaluated in the New Zealand white rabbit. Femoral artery segments of predetermined length are excised, gently turned inside-out, and resutured into their native position. Blood flow is restored, and at varying time intervals, vessel patency is assessed through the direct "milking test." In this study, three groups of 20 arterial inversion grafts of 2, 5, and 10 mm in length are created and evaluated for patency at 1 hour and again at 7 days. The incidence of femoral artery occlusion in this model appears to be an increasing function of arterial inversion graft length both at 1 hour--30 percent (2 mm), 80 percent (5 mm), and 100 percent (10 mm)--and at 7 days--65 percent (2 mm), 90 percent (5 mm), and 100 percent (10 mm). This proportionality suggests the arterial inversion graft may be adjusted in length to provide an incidence of vessel occlusion best suited to the needs of any particular experiment.

Anastomosis, Surgical↗
PubMed1989

Salvage of a failing microvascular free muscle flap by direct continuous intravascular infusion of heparin: a case report.

A free gracilis muscle transfer with skin graft was performed for reconstruction of a type IIIB lower extremity traumatic wound with acute exposure of the distal tibia fracture site and an extensive soft-tissue wound. The free muscle flap failed from a venous thrombosis that was recognized 12 hours postoperatively, and reexploration revealed extensive venous thrombosis throughout the lower leg. The flap was salvaged by direct catheter administration of heparin into the vena comitans of the gracilis artery, which bathed the newly repaired venous anastomosis with an anticoagulating dose of heparin without systemic elevation of the patient's PTT. Ultimate full flap survival and wound healing ensued.

Adult↗
PubMed1989

Purification and properties of glycerol:NADP+ 2-oxidoreductase from Schizosaccharomyces pombe.

Glycerol:NADP+ 2-oxidoreductase (EC 1.1.1.156) was isolated from Schizosaccharomyces pombe, purified and characterized. It had an Mr of 57,000, and SDS-PAGE revealed two polypeptides, of Mr 25,000 and 30,000. Its coenzyme requirement was satisfied exclusively by NADP. The pH optimum for glycerol oxidation was 9.5, for dihydroxyacetone reduction 6.0. Rates of oxidation with some structurally related diols were three- to six-fold lower than for glycerol, while glyceraldehyde and other carbonyl compounds showed negligible rates of reduction. Neither monovalent nor divalent cations activated the enzyme. Apparent Km and Vmax values were determined. The enzyme is similar to glycerol dehydrogenases isolated from Mucor javanicus and from Dunaliella parva but differs considerably from the glycerol:NAD+ 2-oxidoreductase of S. pombe.

Coenzymes↗
PubMed1989

Differential sensitivity of erythrocyte-rich and platelet-rich arterial thrombi to lysis with recombinant tissue-type plasminogen activator. A possible explanation for resistance to coronary thrombolysis.

Acute myocardial infarction is triggered by coronary artery occlusion that may be recanalized by thrombolytic therapy with a success rate of up to 75% only. The resistance of coronary artery occlusion to thrombolysis may either be due to obstruction of the lumen by a nonthrombotic mechanism or by intrinsic resistance of thrombus to dissolution. Coronary arterial thrombi are composed of platelet-rich and erythrocyte-rich material in variable proportions. To evaluate the relative sensitivity of these thrombus components to thrombolysis, we have used two femoral arterial thrombosis models in the rabbit, consisting of erythrocyte-rich clot produced by injecting whole blood and thrombin in an isolated segment and of platelet-rich thrombus spontaneously formed on an everted (inside out) femoral arterial segment. Intravenous infusion of recombinant tissue-type plasminogen activator (rt-PA) at a rate of 30 micrograms/kg/min consistently reperfused arteries occluded with erythrocyte-rich clot (six of six animals compared with zero of six placebo-treated animals, p = 0.002), whereas infusion of 30 or 100 micrograms/kg/min was significantly less efficient for reperfusion of everted segments occluded with platelet-rich material (only four of 12 animals, p = 0.01). Intra-arterial infusion proximal to the occlusion, at a rate of 20 micrograms/kg/min reperfused six of seven rabbits with erythrocyte-rich clots but only one of seven rabbits with occluded everted segments (p = 0.03). A dose of 100 micrograms/kg/min was necessary to reperfuse platelet-rich occlusions in five of six rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

St. Clair Strange procedure: indications, technique, and long-term evaluation.

The pedicled ulnar nerve transfer (St. Clair Strange procedure) preserves the intrinsic blood supply to the transferred nerve and allows bridging of large defects in avascular, scarred wounds. We report our indications for this operation, describe the two operative stages, and report the results in seven patients. After operation progressive median nerve axonal growth in a proximal direction up the ulnar nerve was shown by a median nerve Tinel's sign. Five patients followed for a mean of 10 years achieved protective sensibility in the median nerve distribution. In two of the three patients in whom distal nerve repair was done to the median and ulnar nerve, protective sensibility also returned to the ulnar digits. Localization, stereognoses, and vibratory response was achieved in the majority of digits. All patients had active use of the hand, but none had meaningful two-point discrimination. No changes were found after a superficial radial nerve block excluded any radial nerve contribution. No intrinsic motor functional return was noted. Two patients are currently being followed.

Adolescent↗
PubMed1988

Great toe-to-hand transfer: role of the preoperative lateral arteriogram of foot.

This report correlates the results of the lateral angiogram of the foot with the operative dissection and eventual outcome in 29 patients in whom a great toe-to-hand transfer was performed to treat a traumatic loss of the thumb. Our angiographic findings were confirmed by surgical exploration and indicated that (1) in 20 (70%) of 29 patients the first dorsal metatarsal artery (FDMA) originated from the dorsalis pedis artery, dorsal to the midlongitudinal axis of the first metatarsal bone; (2) in 6 (20%) of 29 patients the FDMA originated from the dorsalis pedis artery, plantar to the midlongitudinal axis of the first metatarsal bone; (3) in the remaining 3 (10%) of 29 patients the arteriogram of the lateral foot indicated that the plantar metatarsal artery supplied the great toe in a dominant pattern, necessitating its use as the donor vessel; and (4) the measured lumenal diameters of the dorsal and plantar metatarsal arteries (mean diameter = 1.30 mm and 1.27 mm, respectively) did not significantly differ. The lateral views of the foot were helpful in permitting distinct identification of the location and size of the metatarsal arteries to the great toe.

Amputation, Traumatic↗
PubMed1988

Multiresistant Staphylococcus aureus: genetics and evolution of epidemic Australian strains.

Molecular and genetic analysis of multiresistant isolates of Staphylococcus aureus from widely separated hospitals in Australia has demonstrated that these are clearly related, and that the predominant strains possess up to three different plasmids, which fall into the following classes: (i) small 1.6 kb plasmids, such as pSK3, which are phenotypically cryptic, (ii) 4.5 kb chloramphenicol resistance plasmids, such as pSK2, and (iii) the pSK1 family of multiresistance plasmids, which range in size from 20 to 42 kb and variously encode resistance to antiseptics and disinfectants, trimethoprim (Tpr), penicillin (Pcr) and the aminoglycosides gentamicin, tobramycin and kanamycin (Gmr Tmr Kmr). Gmr Tmr Kmr is encoded on the pSK1 family plasmids by transposon Tn4001, which was also detected on the chromosomes of some clinical isolates. Tn4001 is composed of inverted repeats of the insertion sequence IS256; these repeats flank a Gmr Tmr Kmr sequence encoding for a 57,000 dalton bifunctional protein with aminoglycoside acetyltransferase [AAC(6')] and phosphotransferase [APH(2")] activities. A Tn4001-like structure, which is defective in transposition but encodes for a Gmr Tmr Kmr determinant homologous with that on Tn4001, occurs on conjugative plasmids from strains isolated in North America. Physical studies indicate that Pcr, via a beta-lactamase, and Tpr, via a trimethoprim-insensitive dihydrofolate reductase (DHFR), are also encoded on the pSK1 family by transposons; these transposons have been designated Tn4002 and Tn4003, respectively. Tn4003 is flanked by direct repeats of the insertion sequence IS257. The evolution of the pSK1 family of multiresistance plasmids is traced through the transposition and genetic rearrangement of resistance determinants. Transposition and genetic rearrangement have also contributed to the evolution of a multiresistant chromosome in Staph. aureus. In the majority of contemporary multiply resistant Staph. aureus strains the determinants for resistance to erythromycin (Emr), fusidic acid, methicillin (Mcr), minocycline, rifampicin, spectinomycin, streptomycin, sulphonamides, tetracycline (Tcr), cadmium (Cdr), and mercury (Hgr) are chromosomally encoded; these strains also possess chromosomally encoded Pcr, via a beta-lactamase. Evidence indicates that some of these determinants, Pcr, Cdr, Hgr, and Tcr, were plasmid encoded in isolates collected from Australian hospitals prior to 1970. Through transposition and site-specific integration, they have since been acquired by the chromosome in more recent Staph. aureus strains.(ABSTRACT TRUNCATED AT 400 WORDS)

Australia↗
PubMed1988

The role of external fixation in the treatment of posttraumatic osteomyelitis.

External skeletal fixation played a central role in the reconstruction of 30 limbs involved in posttraumatic osteomyelitis. The tibia was involved in 15, the femur in six, the ankle in five, and the foot and radius in two each. Of the thirty limbs, 27 were ununited. Positive bacteriology and/or histology was found in each case. A total of 36 frames were used with 20 unilateral half-frame constructs and 16 bilateral transfixion frames. The average duration of external fixation was 60 days. Specific procedures for soft tissue coverage were required in 21 cases and autogenous bone grafting in 26. Loosening and local infection occurred in three of 168 external fixation pins. There were no cases of pin-track osteomyelitis, fractures through pintracks, or neurovascular damage from pin insertion. Infection was controlled in 29 of 30 limbs, with one requiring a below-knee amputation. Skeletal union was achieved in all cases. At an average follow-up of 35 months, 20 of 28 lower limbs in 27 patients tolerated full weight bearing without ambulatory aides. Four used a patellar tendon-bearing polypropylene orthosis, two used a cane, and one a walker. In the 23 patients ambulating without upper-extremity aides, the average time from the start of treatment to reach this functional status was 14 months.

Adult↗
PubMed1988

Human recombinant tissue type plasminogen activator and its effect on microvascular thrombosis in the rabbit.

A new potent thrombolytic agent, human tissue type plasminogen activator (t-PA), has become available for study through recombinant DNA technology. In this series of experiments, we have tested t-PA in a reliable microvascular thrombosis model previously developed in our laboratory. Its action in preventing thrombus formation and lysing fresh clot by direct local infusion and systemic infusion was tested. The results revealed that t-PA was able to keep locally infused vessels open for 4 hours and reopen them after they were allowed to clot in 100 percent of the animals tested. Those vessels exposed only to systemic levels of t-PA achieved by the same local infusion remained thrombosed and were unaffected. Laboratory studies showed no evidence of activation of the systemic lytic state or alteration in coagulation parameters. t-PA has proved to be a protein with characteristics that make it attractive for use in microvascular surgery. The results suggest that further research may lead the way toward clinical use.

Animals↗
PubMed1988

Therapeutic value of intravenous heparin in microvascular surgery: an experimental vascular thrombosis study.

In an attempt to decrease a 10 to 15 percent vascular thrombosis rate leading to graft occlusion, low-dose human-grade heparin was studied to determine if carefully monitored intravenous therapy would increase 7-day patency in a known potent thrombosis model. In New Zealand white rabbits, the type of infusate administered intravenously, either saline (30 animals) or heparin (35 animals), was selected at random after completing a 2-mm arterial inversion graft in the femoral artery. A 72-hour infusion was used in all animals; the control group received sterile saline and the experimental group received a heparin infusion at 45 microliters per hour after a 500-unit bolus. All grafts in both groups were patent at the time of groin closure. Patency in the heparin-perfused group was 67 percent (24 of 35) as compared to 19 percent (6 of 30) in the control group (p less than 0.05) 1 week postoperatively. Scanning electron microscopy showed significantly less dense fibrin deposition and a decrease in the number of aggregated platelets in the heparin-perfused grafts. Partial tissue thromboplastin time values in the experimental group ranged between 55 and 75 seconds (control 20 to 25 seconds). We have shown that heparin, an inexpensive and readily available agent, maintains 1-week microarterial patency and results in few complications in a reliable, reproducible, and versatile thrombosis model. The clinical ramifications of using an antiplatelet agent that diminishes fibrin deposition in microsurgery are apparent.

Animals↗
PubMed1988

Closed complex dorsal dislocation of the middle finger metacarpophalangeal joint: anatomic considerations and treatment.

A rare complex isolated metacarpophalangeal joint dislocation of the middle finger is described, and the pathology is reviewed. The dorsal longitudinal incision used in this case provided excellent exposure for the reduction and helped avoid injury to the digital nerves on the palmar side of the injury. Early mobilization with extension blocking is advocated to maximize joint range of motion postoperatively.

Aged↗
PubMed1988

Management of advanced foot deformities in dystrophic epidermolysis bullosa.

Treatment for the characteristic hand deformities of dystrophic epidermolysis bullosa has been well described in the literature. We present our first experience delineating the surgical treatment for advanced foot deformities in this disease. This case emphasizes the need for release of contractures, the use of split-thickness skin grafts, and the need for rigid fixation to maintain surgical correction until healing is complete.

Adolescent↗