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Biomedical subjects

A T Bishop

Publications and source records attributed to A T Bishop.

At least 19 recordsLinked to original sources
PubMed2000

Experimental carpal reverse-flow pedicle vascularized bone grafts. Part I: the anatomical basis of vascularized pedicle bone grafts based on the canine distal radius and ulna.

We investigated the detailed extraosseous and intraosseous vascular anatomy of the distal radius and ulna in 55 pairs of canine forelimbs. Ten specimens were used for compartment identification. One hundred specimens were investigated after intra-arterial injection with red latex or Batson's compound. The extraosseous vascular network, including the nutrient artery location, was studied by delicate dissection and soft tissue digestion. Two superficial and 4 deep arteries were found on the dorsal aspect, with constant relationships to the retinaculum. On the palmar aspect, bony nutrient vessels rose from the branches of the radial artery (descriptive anatomy). The vascular supply of the canine distal forelimb was very consistent and enabled the design of 5 vascularized pedicle bone grafts similar to those described in humans (applied anatomy). These reverse-flow pedicle grafts may be placed in the carpus, allowing the canine forelimb to serve as an experimental model for the study of vascularized carpal bone grafting. (J Hand Surg 2000; 25A:34-45.

Animals↗
PubMed2000

Experimental carpal reverse-flow pedicle vascularized bone grafts. Part II: bone blood flow measurement by radioactive-labeled microspheres in a canine model.

Reverse-flow pedicle vascularized bone grafts (VBGs) from the radius, commonly used for carpal nonunion and avascular necrosis, provide superior clinical results. In this experimental study bone blood flow in canine distal radius VBGs was measured to determine the status of the bone circulation immediately after elevation (group 1) and 2 weeks later (group 2). Immediate VBG flow (group 1) was substantial, but significantly less than the contralateral undisturbed distal radius (8.42 mL/min/100 g and 16.53 mL/min/100 g, respectively). At 2 weeks after surgery (group 2) VBG flow was compared with nonvascularized control grafts. Vascularized bone graft flow was significantly higher than group 1 (mean, 33.72 mL/min/100 g). Minimal flow was seen in the conventional graft control (0.62 mL/min/100 g). This study demonstrates that reverse-flow pedicle radius VBG maintain enhanced bone circulation long-term. Given the similarity of human and canine distal radius vascular anatomy, these data support the clinical use of reverse-flow VBG for carpal pathology. (J Hand Surg 2000; 25A:46-54.

Animals↗
PubMed2000

Diagnosis and management of hamate hook fractures.

Hamate hook fractures, although uncommon, are now recognized with increasing frequency because of the increase in popularity of racket sports and golf. Careful clinical evaluation and adjunctive radiologic investigation help establish the diagnosis. Acute nondisplaced fractures can heal with immobilization, while displaced fractures and nonunions typically require open reduction and internal fixation (acute fractures) or hook excision.

Athletic Injuries↗
PubMed1999

Dynamic axial carpal instability: a case report.

The concept of distal carpal row dissociation is not new. It has occurred secondary to high-energy crush or blast injuries, with resultant axial dislocations of both carpal rows and metacarpals. Axial carpal sprains without disruption or dynamic axial carpal instability have not been previously described. The evaluation of this new type of carpal instability with radiographs, tomography, arthrography, and magnetic resonance imaging failed to demonstrate its etiology. Arthroscopic evaluation of the midcarpal and radiocarpal joints demonstrated a dynamic axial carpal instability with incompetence of the capitohamate and scapholunate ligaments. Stabilization of the axial instability by capitohamate arthrodesis relieved the chronic wrist pain.

Adult↗
PubMed1999

Extensor triggering in de Quervain's stenosing tenosynovitis.

Extensor triggering is an uncommon but recognized component of de Quervain's stenosing tenosynovitis. In a retrospective review of 827 patients with the diagnosis of de Quervain's disease over a 5-year period, 11 patients with 13 affected wrists were identified who had demonstrable triggering by both history and physical examination (prevalence of 1.3%). One wrist underwent surgical release without conservative treatment. The remaining 12 wrists were initially treated with nonoperative modalities. Failure of conservative treatment as defined by recurrent triggering and pain occurred in 7 wrists, of which 5 underwent surgical release. At the time of surgery, all wrists were noted to have synovitis, separate compartments for the extensor pollicis brevis and abductor pollicis longus tendons, and no intratendinous nodules. After an average follow-up period of 42 months (range, 5.7-94.5 months) there were no recurrences of triggering after surgical treatment. Seven of 12 wrists with triggering de Quervain's stenosing tenosynovitis failed nonoperative treatment. Triggering or locking in extension is an uncommon symptom in de Quervain's stenosing tenosynovitis and demonstrates a more recalcitrant course when treated nonoperatively.

Adolescent↗
PubMed1999

Kienböck's disease and gout.

A relationship between gout and Kienbock's disease has been proposed on the basis of a previously published case report. A review of patients at our institution identified a single case with the combination of both Kienbock's disease and gout. We believe that the association is coincidental.

Arthroscopy↗
PubMed1999

Microvascular reconstruction of the traumatized thumb.

Microvascular reconstruction of the thumb is technically exacting and requires a firm grasp of anatomic variations of toe blood supply. Careful preoperative planning and meticulous microsurgical technique result in a low primary failure rate and maximize functional and aesthetic results.

Humans↗
PubMed1999

The risk of persistent paresthesia is not increased with repeated axillary block.

UNLABELLED: Neurologic deficits are noted on physical examination in approximately 0.2%-19% of patients after regional anesthetic techniques. Laboratory and clinical studies suggest that a subclinical neuropathy occurs much more often. Performing a regional anesthetic technique during this period may result in additional nerve trauma. We evaluated the frequency of neurologic complications in patients undergoing repeated axillary block. A total of 1614 blocks were performed on 607 patients. The median number of blocks per patient was two (range 2-10 blocks). The median interval between blocks was 12.6 wk, including 188 (31%) patients who received multiple blocks within 1 wk. Sixty-two neurologic complications occurred in 51 patients for an overall frequency of 8.4%. Of the 62 nerve injuries, 7 (11.3%) were related to the anesthetic technique; the remaining 55 (88.7%) were a result of the surgical procedure. Patient age and gender, the presence of preexisting neurologic conditions, a surgical procedure to a nerve, and total number of blocks did not increase the risk of neurologic complications. No regional anesthetic technique risk factors, including elicitation of a paresthesia, selection of local anesthetic, or addition of epinephrine, were identified. The success rate was higher with the paresthesia technique than with nerve stimulator technique or transarterial injection, and with use of mepivacaine versus bupivacaine. We conclude that the frequency of neurologic complications in patients undergoing repeated axillary block is similar to that in patients receiving a single regional technique. These patients are not likely to be at increased risk of neurologic complications. IMPLICATIONS: The risk of neurologic complications was not increased in patients who underwent multiple axillary blocks, even within a 1-wk interval. No risk factors for anesthetic-related complications were identified. However, block success rate was increased with the paresthesia technique and the injection of mepivacaine versus bupivacaine.

Adrenergic Agonists↗
PubMed1998

Interaction of endothelial eccrine mechanisms and human adrenomedullin on vascular resistance in canine bone.

Adrenomedullin is a novel peptide known to be one of the most potent vascular smooth muscle relaxing agents in vivo. The aim of this study is to investigate the effect of adrenomedullin in relation to nitric oxide, prostaglandins and endothelium-derived hyperpolarized factor (EDHF). A 0.1-ml bolus of 1 nmol human adrenomedullin is a potent inhibitor of the pressor response to exogenous norepinephrine infusion in an ex vivo canine tibia perfusion model for a duration of at least 70 min (P < 0.005). This attenuation of vascular smooth muscle contraction occurs even when nitric oxide production is blocked by NG-monomethyl-L-arginine acetate (L-NMMA) infusion and EDHF is blocked by tetraethylammonium infusion, although the effect is of shorter duration (at least 10 min). Indomethacin as well does not affect the suppression of norepinephrine-induced vascular smooth muscle contraction. Based on these data, human adrenomedullin has both nitric oxide- and EDHF-dependent mechanism as well as a nitric oxide- and EDHF-independent mechanism.

Adrenomedullin↗
PubMed1998

End-to-end versus end-to-side arterial anastomosis patency in microvascular surgery.

The patency rates of microsurgical end-to-end and end-to-side anastomosis in the rat carotid artery were studied. Seventy end-to-end and seventy end-to-side arterial anastomoses, using 10-0 nylon interrupted sutures, were performed on 140 Sprague-Dawley rats. Findings indicated 100% patency in end-to-end as well as end-to-side immediately and 1 week post-anastomosis. This investigation suggests that there is no significant advantage between the methods studied based on vessel patency alone. The decision to perform an end-to-end vs. an end-to-side arterial anastomosis should be based upon the clinical circumstances encountered, since no significant difference in patency rates exists.

Anastomosis, Surgical↗
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↗