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Biomedical subjects

A T Bishop

Publications and source records attributed to A T Bishop.

At least 37 records · Page 2Linked to original sources
PubMed1998

Lunotriquetral ligament properties: a comparison of three anatomic subregions.

The physical attributes of 3 subregions of the lunotriquetral ligament were tested in a computer-controlled multiaxis testing machine using 12 specimens. This allowed measurement of forces, moments, and displacements when ligaments were subjected to distraction, dorsopalmar translation, proximal-distal translation with a 20 N limit, and rotation with a 0.5 Nm limit. After an intact test run, selected subregions were cut randomly. Together with an additional 12 bone-ligament-bone complexes, specimens were tested to failure with servohydraulic load at 5 mm/s. The palmar subregion was thickest (2.3 +/- 0.3 mm), the dorsal and proximal progressively less. Intact rotational displacement was 35 degrees +/- 5.1 degrees, dorsopalmar displacement was 1.6 +/- 0.4 mm and 1.2 +/- 0.5 mm, respectively, proximal-distal displacement was 1.8 +/- 0.5 mm and 1.3 +/- 0.5 mm, respectively, and distractional displacement was 0.3 +/- 0.1 mm. The dorsal subregion provided 62.3% +/- 27.1% of the rotational resistance. The palmar subregion resisted 67.3% +/- 14.1% of palmar translation, while with dorsal translation both regions resisted equally. Rotational displacement increased 15.3 degrees +/- 5.6 degrees after dorsal subregion sectioning. The palmar component failure force was 301 +/- 36 N; the dorsal, 121 +/- 42 N; and the proximal, 64 +/- 14 N.

Biomechanical Phenomena↗
PubMed1998

Function of the vascular endothelium after hypothermic storage at four degrees Celsius in a canine tibial perfusion model. The role of adrenomedullin in reperfusion injury.

The function of the vascular endothelium after cold storage at 4 degrees Celsius for one, three, five, and seven days was investigated in a canine tibial perfusion model. Function was assessed in terms of changes in perfusion pressure, changes in the concentration of endothelin in the venous effluent from the perfused tibiae, adrenomedullin-induced vascular smooth-muscle relaxation, and norepinephrine-induced pressor responses in the presence of acetylcholine, N(G)-monomethyl-L-arginine acetate (an inhibitor of nitric oxide synthesis), or indomethacin (an inhibitor of prostaglandin synthesis) in phase 1 of the study. In phase 2 of the study, the effect of the infusion of tetraethylammonium (a potassium-channel blocker that inhibits the activity of endothelium-derived hyperpolarized factor) was analyzed. The baseline perfusion pressures increased in a time-dependent manner (p < 0.05). In tibiae that had been stored for one or three days, the production of endothelin-1 was less than one picogram per milliliter, but it markedly increased to a mean (and standard error of the mean) of 8.7 +/- 3.2 and 10.8 +/- 4.3 picograms per milliliter in tibiae that had been stored for five and seven days, respectively (p < 0.05). Acetylcholine attenuated the norepinephrine-induced pressor response in all groups (storage at 4 degrees Celsius for one, three, five, or seven days) compared with the response in the control tibiae (p < 0.05). Perfusion of acetylcholine in the tibiae that had been stored for three days significantly attenuated the pressor response to norepinephrine compared with that in the tibiae that had been stored for five days (p < 0.05). In the presence of N(G)-monomethyl-L-arginine acetate, the norepinephrine-induced pressor response significantly increased only in the tibiae that had been stored for one day (p < 0.05). In the presence of indomethacin, the norepinephrine-induced pressor response significantly decreased in the tibiae that had been stored at 4 degrees Celsius for one, three, or five days (p < 0.05). Infusion of adrenomedullin relaxed vascular smooth muscle in the tibiae that had been stored for one, three, five, or seven days (p < 0.05). In phase 2 of the study, perfusion of tetraethylammonium in the presence of acetylcholine increased the norepinephrine-induced pressor response in the tibiae that had been stored at 4 degrees Celsius for seven days to a mean of 168 +/- 20 per cent, whereas perfusion with acetylcholine alone attenuated the norepinephrine-induced pressor response to a mean of 54.6 +/- 3.7 per cent.

Adrenomedullin↗
PubMed1997

Autogenous fibular graft and silicone implant arthroplasty following resection of giant cell tumor of the metacarpal: a report of two cases.

Two cases of reconstruction after resection of giant cell tumor of the distal metacarpal are reported in which reconstruction was achieved with a nonvascularized fibular autograft and silicone metacarpophalangeal joint arthroplasty. At 2-year and 1-year follow-up evaluation, respectively, the patients were found to be doing well. This method of reconstruction appears reliable and presents the possibility for vascularized reconstruction if that is thought necessary.

Adult↗
PubMed1997

Effect of the duration of room-temperature ischemia on function of the vascular endothelium: the role of adrenomedullin in reperfusion injury.

The function of the vascular endothelium after storage at room temperature (24 degrees Celsius) for four, eight, and twenty-four hours was investigated with use of an ex vivo canine tibial perfusion model. Function was assessed in terms of changes in perfusion pressure and changes in the concentration of endothelin-1 in the venous effluent of the perfused tibiae. Endothelin-1 is a potent vasoconstrictor that is produced in low concentrations by normal endothelial cells and in increased concentrations by injured vascular endothelial cells. The mean perfusion pressures at flow rates of 1.0 and 1.5 milliliters per minute were significantly higher in the tibiae that had been stored for eight hours than in the tibiae that had been stored for four hours (p < 0.05), and they were significantly higher in the tibiae that had been stored for twenty-four hours than in the tibiae that had been stored for four or eight hours (p < 0.05). The increase in perfusion pressure with increasing duration of storage was associated with an increase in production of endothelin-1. The production of endothelin-1 in the tibiae that had been stored for eight hours (10.6 +/- 0.46 picograms per milliliter) was approximately ten times greater than that in the tibiae that had been stored for four hours (1.1 +/- 0.29 picograms per milliliter). The tibiae that had been stored for twenty-four hours had 19.1 +/- 1.5 picograms of endothelin-1 per milliliter, nearly twice that produced in the tibiae that had been stored for eight hours. Injection of acetylcholine demonstrated muscarinic receptor-mediated vasodilation in the tibiae that had been stored for four hours. In contrast, the tibiae that had been stored for eight and twenty-four hours had no evidence of acetylcholine-induced vasodilation of baseline perfusion vascular smooth-muscle tone. However, there was some preservation of endothelium-dependent vascular smooth-muscle relaxation in the tibiae that had been stored for eight and twenty-four hours, as norepinephrine-induced vascular smooth-muscle contraction was significantly greater in the presence of N(G)-monomethyl-L-arginine acetate (p < 0.05). Moreover, in the second phase of the study, a bolus injection of calcium ionophore A23187 in tibiae that had been stored for twenty-four hours relaxed vascular smooth muscle. Adrenomedullin, a novel peptide with known vasodilator properties, relaxed vascular smooth muscle in all three groups and also attenuated the pressor response to norepinephrine. In conclusion, the function of the vascular endothelium was impaired after storage at room temperature for four hours. However, the vascular endothelium in the tibiae that had been stored for twenty-four hours maintained some function with regard to the production of nitric oxide. The effect of adrenomedullin as a potent vasodilator was observed in the tibiae that had been stored for four, eight, and twenty-four hours.

Acetylcholine↗
PubMed1996

Effect of human adrenomedullin on vascular resistance of the canine tibia.

An ex vivo model of a perfused canine tibia was used to investigate the effect of human adrenomedullin, a novel peptide with known vasodilator properties, on the vascular resistance of bone. Human adrenomedullin has a potent and long-lasting vasodilator effect in the canine tibia following precontraction of vascular smooth muscle by infusion of prostaglandin F2 alpha. A 0.1 ml bolus injection of 10(-5) M human adrenomedullin suppressed the pressor response of the canine tibia preparation to an infusion of norepinephrine by 43-52% for a duration of 100 minutes. An injection of 10(-6) adrenomedullin suppressed the pressor response to an infusion of norepinephrine by 22-23% for a duration of 40 minutes. These data suggest that human adrenomedullin may be a potent and long-acting vascular smooth-muscle relaxant in bone.

Acetylcholine↗
PubMed1996

Effect of human adrenomedullin on a canine tibial perfusion model in the absence of vascular endothelium.

The effect of human adrenomedullin was investigated using an ex vivo perfused canine tibial model in the absence of vascular endothelium. Adrenomedullin is a novel peptide with known vasodilator properties. In this model, a 0.1 ml bolus injection of 10(-5) M of either acetylcholine or adrenomedullin decreased vascular resistance in tibial preparations precontracted with prostaglandin F2 alpha by 88.3 +/- 3.0% and 92.8 +/- 2.8%, respectively, in the presence of vascular endothelium. Conversely, a 0.1 ml bolus injection of 10(-5) M acetylcholine produced a constrictor response after removal of vascular endothelium. A 0.1 ml bolus injection of 10(-5) M adrenomedullin decreased the baseline perfusion pressure in a dose-dependent manner for a duration of 20 minutes and also attenuated the pressor response to exogenous norepinephrine injection for at least 10 minutes compared with the control study (p < 0.05) in the absence of vascular endothelium. These data suggest that human adrenomedullin relaxes blood vessels in bone by a direct action on vascular smooth-muscle cells. In addition, the attenuation effect of human adrenomedullin on pressor responses to exogenous norepinephrine injection is independent of vascular endothelium.

Acetylcholine↗
PubMed1996

The capitohamate ligaments. A comparison of biomechanical properties.

The physical attributes of the three capitohamate interosseous ligaments were tested in a computer-controlled multi-axis testing machine using 12 human cadaver specimens. After an intact test run, selected ligaments were cut in random sequence and the test repeated. The remaining ligaments were tested to failure with servohydrolic stress at 5 mm/second. In the intact joint complex, the average dorsopalmar rotational displacement was approximately 9 degrees in each direction. Under the load limit, the dorsopalmar translational displacement averaged 0.9 mm and 0.5 mm respectively, proximal-distal translational displacement averaged 0.8 mm and 0.4 mm respectively, and distractional displacement averaged 0.3 mm. Based on the sequential sectioning it was found that the dorsal ligament provided 76% (SD 14) of the rotational resistance with palmar rotation of the capitate and 44% (SD 19) of translational constraint with palmar translation of the capitate. The deep ligament provided 51% (SD 15) of the rotational resistance with dorsal rotation of the capitate and 63% (SD 24) of translational resistance with dorsal translation of the capitate. With proximal-distal translation, the dorsal ligament was the most important constraint in each direction. In resisting distraction, each of the three ligaments was equally effective. Failure testing showed the deep ligament was strongest at 289 N, followed by the palmar at 171 N and the dorsal at 133 N.

Adult↗
PubMed1995

The arterial blood supply of the distal radius and ulna and its potential use in vascularized pedicled bone grafts.

We investigated the extra- and intraosseous blood supply of the distal radius and ulna (descriptive anatomy) and defined potential vascularized pedicled bone grafts to the carpal bones (applied anatomy). We studied 41 cadaver upper limbs using several techniques including angiography, Batson's compound and latex injections, and bone clearing using a modified Spalteholtz technique. Several known arteries were described in greater detail, and numerous previously undescribed arteries were found and investigated. Vascularized pedicled grafts have potential applicability for carpal pathology. Several grafts have been described from the radius, second metacarpal, and pisiform. We have identified several vascular pedicles that provide the hand surgeon with additional options. Some of these grafts provide a wider arc of rotation, greater ease of harvest and/or improved vascularity compared to many previously described grafts.

Adult↗
PubMed1995

New dorsal capsulotomy for the surgical exposure of the wrist.

A reliable, safe approach to the wrist through fiber-splitting dorsal capsulotomies has been developed. The dorsal wrist capsule is exposed by subperiosteally elevating the fourth and fifth extensor compartments ulnarly and translocating the extensor pollicis longus tendon with the radial wrist extensor tendons radially. The midcarpal joint and the radial half of the radiocarpal joint are exposed by longitudinally splitting the dorsal radiocarpal and dorsal intercarpal ligaments, with the apex at the triquetrum. The flap created is elevated radially, detaching the dorsal capsule from the radius to the level of the styloid process. For exposure of the ulnocarpal joint, the dorsal radiocarpal ligament is split longitudinally, and the capsule is incised along the extensor carpi ulnaris tendon subsheath proximally to the level of the triangular fibrocartilage, with the apex at the triquetrum. The flap created is elevated proximally. Exposure of the wrist is excellent, stability of the carpal bones is maintained, and closure is simplified using this approach.

Carpal Bones↗
PubMed1995

Arthrodesis of the knee with a vascularized fibular rotatory graft.

We retrospectively reviewed the records of thirteen patients who had been managed with an arthrodesis of the knee with use of a vascularized graft from the ipsilateral fibula and fixation with an intramedullary rod. The indications for the operation included a large skeletal defect secondary to the resection of a tumor about the knee in eight patients, an infection at the site of an arthroplasty in four (with failure of a previous conventional arthrodesis in three of the four), and severe rheumatoid gonarthrosis as well as a persistent non-union of the distal part of the femur in one. The average age of the patients at the time of the operation was forty-three years (range, twenty-six to seventy-six years). Most of the patients had had multiple previous procedures (thirty-three operations had been performed in ten patients). Twelve of the thirteen patients had a solid fusion and a successful result after an average duration of follow-up of fifty-one months (range, eight to ninety-three months). The remaining patient, who had had four previous arthroplasties, had a recurrence of an infection seven months after the operation and was managed with an amputation. Six complications--including two superficial wound infections, one deep wound infection, one deep venous thrombosis, one transient peroneal-nerve palsy, and one delayed union--occurred in three patients.

Adult↗
PubMed1995

Arthrodesis of the ankle with a free vascularized autogenous bone graft. Reconstruction of segmental loss of bone secondary to osteomyelitis, tumor, or trauma.

Reconstruction after massive loss of bone about the ankle is difficult because of the limited amount of surrounding soft tissue and because of technical factors pertaining to adequate internal or external fixation. Conventional techniques are often unsuccessful because of the frequency of associated deep infection and of previous operative procedures. In this report, we describe eleven patients with a large defect of the distal aspect of the tibia who were managed at our institution with arthrodesis of the ankle with free vascularized bone graft. The defect was related to a tumor resection; an acute open fracture with bone and soft-tissue loss caused by a shotgun injury; or osteomyelitis, either alone or in combination with septic arthritis, with chronic non-union following a fracture of the ankle. A free fibular graft was used in osseous defects that were larger than four centimeters, and a free iliac-crest graft was used in smaller defects. Osteocutaneous or osteomuscular flaps were constructed to cover accompanying soft-tissue defects when necessary. A successful fusion was obtained in nine of the eleven patients. The results in the remaining two were regarded as clinical failures, and a below-the-knee amputation was performed. One amputation was done because of recurrent infection and the other, because of failure of the fracture to unite after four years.

Adolescent↗
PubMed1994

Atypical Mycobacterium infections of the upper extremity.

Thirty-three patients with culture-positive atypical Mycobacterium infections of the upper extremity underwent surgical debridement and antimicrobial therapy. The causative atypical organism was M. marinum in 12 cases, M. avium-intracellulare in 7, M. terrae in 4, M. chelonei in 4, M. kansasii in 3, M. fortuitum in 2, and M. ulcerans in 1. The tenosynovium was the most common location of infection (14 patients). The average follow-up period was 36 months. Duration of antimicrobial therapy averaged 10 months. The average delay between onset of symptoms to correct diagnosis was 1 year. There were seven superficial infections; six were caused by M. marinum and one was caused by M. ulcerans. All of these cutaneous infections resolved following incisional or excisional biopsy and pharmacologic therapy. The remaining 26 infections involved the deeper tissues, and M. avium-intracellulare was the most common organism. The immune status of the host was an overwhelming predictor of eventual outcome. In the 15 patients with competent immune systems, resolution occurred in 13. However, in the immunocompromised patient population, only 4 of the 10 had resolution of deep infection at time of the follow-up evaluation.

Adolescent↗
PubMed1994

Tension wire fixation of avulsion fractures at the thumb metacarpophalangeal joint.

Avulsion fractures of the thumb metacarpophalangeal joint require adequate treatment to prevent instability or articular incongruity. Open reduction and internal fixation may be difficult because of the small fracture fragment size. Nine patients underwent acute open reduction and tension wire fixation of displaced or rotated avulsion fractures. Follow-up examination was at approximately 26 months. All fractures healed in anatomic alignment without instability or articular incongruity. Pain, stiffness, and loss of pinch, were subjectively rated as none in six patients and mild in three. The injured thumb demonstrated firm stability in extension and 30 degrees flexion in all patients. Metacarpophalangeal and interphalangeal motion averaged 77% and 97% of the opposite hand respectively. Planar and palmar abduction averaged 96%. Pinch strength in apposition averaged 97% and in opposition 99% of the uninvolved hand. Grip strength was 96% of the contralateral extremity.

Adolescent↗