Biomedical subjects

M B Wood

Publications and source records attributed to M B Wood.

At least 19 recordsLinked to original sources

PubMed1992

Antagonist drugs and bone vascular smooth muscle.

An ex vivo canine tibia model was used to quantitate the specific adrenergic subtype contribution in bone vasculature. Tibiae were obtained from mongrel dogs, the nutrient artery was catheterized, and the bone was placed in an ex vivo perfusion apparatus at constant flow. Perfusion was accomplished using oxygenated Krebs-Ringer solution. A norepinephrine dose-response curve was obtained by using incremental single bolus doses. Each bone was perfused with a vasoactive drug at a standard physiologic dosage. After 30 min of perfusion, a second norepinephrine dose-response curve was generated. The degree of attenuation of the norepinephrine dose-response curve, as determined by the total area under the curve, was interpreted as the relaxation effect of the drug on the smooth muscle of the vascular bed. Prazosin (alpha 1-receptor antagonist), rauwolszin (alpha 2-receptor antagonist), propranolol (beta-receptor antagonist), and diltiazem (calcium-entry inhibitor) were evaluated. Our data suggest that alpha 1 and alpha 2 adrenergic receptor antagonism results in a quantitatively similar attenuation of norepinephrine-induced vascular smooth muscle contraction. Calcium-entry antagonism produced less, but significant, attenuation of smooth muscle contractility. Beta-adrenergic receptor blockade yielded only a slight, although consistent, reduction in reactivity. Simple perfusion with Krebs-Ringer solution had no effect.

Animals↗

PubMed1992

The effect of hypothermic ischemia on the alpha-adrenergic mechanisms of the canine tibia vascular bed.

The effect of hypothermic ischemia on alpha-1 and -2 adrenergic receptor mediated vasoconstriction has been studied in an in vitro perfused canine tibia preparation. Bones were perfused at a constant rate with aerated (95% O2, 5% CO2) modified Krebs Ringer solution and the effect of bolus injections of norepinephrine (0.025-6.4 nmol) on the perfusion pressure was studied. For all bones the first dose-response curve was produced under control conditions. In one group the second dose-response curve was generated during a constant infusion of prazosin (alpha-1 adrenergic antagonist); in another it was produced during a constant infusion of rauwolscine (alpha-2 adrenergic antagonist); in the control group it was generated under control conditions. The results demonstrate that, after 48 h of hypothermic ischemia, alpha-1 adrenergic-mediated vasoconstriction was significantly attenuated (p less than 0.001). However, alpha-2 adrenergic-mediated vasoconstriction was unaffected by increasing periods of hypothermic ischemia.

Animals↗

PubMed1992

Endothelial control of long bone vascular resistance.

This in vitro study investigates whether intraosseous endothelial cells can regulate long bone blood flow by secretion of vasodilator prostaglandin and EDRF (endothelium-derived relaxing factor). Canine tibia were perfused through the nutrient artery at a constant flow rate, and the increases in perfusion pressure caused by standard doses of norepinephrine were recorded first under control conditions and then during acetylcholine infusion. Acetylcholine attenuated the norepinephrine pressure responses (-62 +/- 3%). This attenuating effect of acetylcholine was partially abolished by inhibition of prostaglandin synthesis (-20 +/- 6%) and completely abolished by inhibition of EDRF synthesis (+73 +/- 43%) or combined inhibition of prostaglandin and EDRF synthesis (+134 +/- 30%). These results are statistically significant (p less than 0.0001) and suggest that both EDRF and vasodilator prostaglandin are synthesized by intraosseous endothelial cells, and can modify long bone vascular resistance. Thus, as in other organs, intraosseous endothelial cells may provide bone with an autoregulatory control mechanism and enable it to respond to a diverse group of vasodilator stimuli.

Acetylcholine↗

PubMed1992

Failure of perfusion with oxygenated Krebs-Ringer solution to preserve the eccrine function of the vascular endothelium in bone.

An ex vivo canine tibia preparation was perfused at a constant rate with aerated (95% O2-5% CO2) Krebs-Ringer solution for 24 h. Bolus injections of norepinephrine (0.125-0.5 micrograms) were given and then acetylcholine (5 x 10(-5) M) was used to stimulate endothelial production of smooth muscle relaxing factors. Following 1 h of perfusion the addition of acetylcholine resulted in significant attenuation of the response to norepinephrine (p < 0.001). After 4 h perfusion acetylcholine did not attenuate the norepinephrine response, but addition of L-arginine (the precursor of endothelial-derived relaxing factor) resulted in significant attenuation in the presence of acetylcholine (p < 0.005). At 6, 12, and 24 h the acetylcholine did not attenuate the norepinephrine response. It is concluded that normothermic, continuous perfusion with oxygenated Krebs-Ringer solution results in normal endothelial eccrine activity up to 1 h. Following this period there is substrate depletion but endothelial eccrine function can be demonstrated for up to 4 h. At 6 h this function cannot be demonstrated, suggesting degradation of the functional integrity of the endothelium.

Acetylcholine↗

PubMed1992

Hand replantation after 54 hours of cold ischemia: a case report.

A number of case reports and series have reported successful replantation after prolonged periods of ischemia. However, the acceptable range of normothermic and hypothermic ischemic storage remains controversial. There is little question that the tolerance of composite tissue for ischemia is dependent on the quantity of contained skeletal muscle. We report a successful hand replantation after 54 hours of cold ischemia. We believe that this case documents the longest anoxic period yet reported for successful hand replantation. We further believe that the functional results obtained confirm the value of hand replantation even after such a prolonged ischemic interval.

Adolescent↗

PubMed1992

Finger and hand replantation. Surgical technique.

An approach to the technique of either finger, thumb, or hand replantation is presented in this article. Acceptable alternative approaches exist, but I have found those techniques described as practical and useful. Variations of these techniques will be necessary depending on any number of circumstances, but these considerations should be individualized to the specific patient and injury pattern.

Amputation, Traumatic↗

PubMed1992

Polydigit replantation.

A comparison of two fundamentally different techniques of multiple digit replantation is studied: a digit-by-digit versus structure-by-structure method. We conclude from this review that the structure-by-structure method is advantageous in terms of the shorter duration of the surgical procedure and possibly in terms of the survival rate of the replanted digits.

Adolescent↗

PubMed1992

Vascularized bone transfer.

We evaluated the results of reconstruction of a skeletal defect with use of a vascularized bone graft from the iliac crest or fibula in 160 patients who had been managed consecutively between 1979 and 1989. The indications for the procedure were a skeletal defect including non-union, resulting from resection of a tumor; traumatic bone loss; osteomyelitis; or a congenital anomaly. The average duration of follow-up was forty-two months (range, twelve to 112 months). For the entire series, the rate of union after the primary procedure was 61 per cent and the over-all rate at the latest follow-up examination (including the patients who had a secondary procedure) was 81 per cent. In a subgroup of seventy-six patients who had union after the primary procedure and did not have additional treatment, the average interval until union was six months and the average interval until full activity was sixteen months. The results were more favorable for the patients who had had reconstruction for resection of a tumor (of sixty-nine patients, fifty-six had union), for a congenital anomaly (of six patients, five had union), or for a non-union without infection (of twenty-five patients, twenty-three had union). The results were less satisfactory for patients who had had the reconstruction for bone loss due to osteomyelitis (of sixty patients, forty-six had union). Our data suggest that vascularized bone transfer for the reconstruction of large skeletal defects is a valuable procedure in appropriately selected patients.

Adolescent↗

PubMed1992

[Vascularized fibula transfer. A review].

The first vascularized fibula transfer was done by Ueba et al. (1983) in 1974 and has since become a standard technique for special indications in the English, French, Japanese and Chinese-world. Within the last 5 years this technique has received more and more attention in the German-speaking countries. The vascularized fibula transfer is successfully used to reconstruct segmental bone defects larger than 5 to 8 cm that are caused by trauma, tumor, pseudarthrosis or congenital defects. When used to treat osteomyelitis, the vascularized fibula transfer failed to fulfill expectations. Bone defects smaller than 10 cm can also be treated by vascularized iliac crest transfer. To achieve rapid healing, the following points must be followed carefully: when treating osteomyelitis, the infection must be healed--negative cultures and good granulation tissue--prior to bone transplantation. Application of systemic or local antibiotics and aggressive debridement of necrotic bone and soft tissue must be carried out until the cultures taken from the wound are negative. Soft tissue defects must be treated by soft tissue transfer in order to facilitate wound closure with well-vascularized tissue. Vascularized bone transfer should be the treatment of choice for the femur and upper extremities. Precise preoperative planning, especially in high-energy trauma cases, reduces the complication rate. Rigid internal fixation of the bone graft with the recipient site by a smaller proximal and distal plate or by a plate bridging the whole bone defect running parallel to the fibula graft leads to rapid healing without malalignment.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Neoplasms↗

PubMed1992

Microvascular reconstruction of congenital anomalies and post-traumatic lesions in children.

A series of toe-to-hand transfers in children with congenital or post-traumatic deficits is reported to emphasize the role of microvascular reconstruction as an important alternative. Morbidity to the donor site is almost negligible, and the functional improvement to the hand is reasonably good considering the young age of the patients. Functional results are limited by the lack of full motion, soft-tissue contractures, sensory recovery, and the delay in cortical reeducation. We were surprised to find a relatively high number of vascular anomalies in the foot (both traumatic as well as congenital). Abnormalities in the transferred toe can limit the function of the hand, and the best (not worse) tissues available should be transferred. The importance of digit positioning to provide prehensile pinch and grasp as the ultimate goal needs to be emphasized so that opposing fingers rather than cosmetic fingers result in effective hand use. We recommend this operative procedure in selected patients along with other reconstructive alternatives, taking care in the selection process to consider factors related to both asthetic improvement of the hand as well as long-term functional return.

Child↗

PubMed1992

Surgical management of chronic ulnar collateral ligament insufficiency of the thumb metacarpophalangeal joint.

We studied 33 patients with "gamekeeper's thumb" who underwent surgical treatment comprising ulnar collateral ligament (UCL) advancement in 14, arthrodesis in 11, reconstruction in 6, and primary repair in 2. Results were satisfactory in 76% of the cases and unsatisfactory in 24%. From our study and review of the literature, we concluded that the best results are obtained after surgical treatment in the acute stage, because results are inconsistent and poorer after treatment of chronic lesions; reconstructive procedures based on the surgical pathology are recommended over UCL advancement and late primary repairs; and arthrodesis is a reliable salvage procedure.

Adolescent↗

PubMed1991

The effects of ischemia on long bone vascular resistance.

An in vitro canine tibia model was used to assess the effects of 48 h of hypothermic (4 degrees C) ischemia on bone vascular resistance and on responsiveness of intraosseous blood vessels to circulating norepinephrine. Three groups of bones were studied: Group I (n = 11), 48 h hypothermic ischemia; Group II (n = 11), 48 h hypothermic ischemia with pretreatment with allopurinol and oxypurinol; and Group III (n = 10), no ischemia. Resting vascular resistance in both ischemic groups (79 and 74 mmHg/ml/min) was significantly higher (p less than 0.0001) than in the nonischemic group (22 mmHg/ml/min). Effects of norepinephrine on vascular resistance were significantly greater in both ischemic groups (p less than 0.004). In all three groups, acetylcholine infusion attenuated the increases in perfusion pressure caused by norepinephrine. This demonstrates secretion of endothelial-mediated relaxing factors (EDRF) and prostaglandin for up to 48 h of hypothermic ischemia. As no significant differences were detected between the two ischemic groups, this study failed to demonstrate any protective effect of xanthine oxidase inhibitors.

Acetylcholine↗

PubMed1991

Pedicled radial forearm flaps for recalcitrant defects about the elbow.

Chronic, open wounds about the elbow frequently require flap coverage. Skin grafts, local transposition flaps, muscle transposition flaps, and two-staged pedicled flaps from the chest and abdomen as well as free tissue transfers have all been reported. Recalcitrant elbow defects in patients in whom these previous flaps have failed are especially challenging to the upper extremity reconstructive surgeon. We have successfully employed pedicled radial forearm flaps in three patients in whom one or more previous flaps have failed.

Aged↗

PubMed1991

Ulnar artery thrombosis and the role of interposition vein grafting: patency with microsurgical technique.

Eight consecutive cases of chronic ulnar artery thrombosis at the wrist managed with microsurgical interposition vein grafting were evaluated for long-term patency and clinical results. At a minimum of one-year follow-up, seven of eight vein grafts (88%) were patent by Doppler and Allen's tests. For the patent grafts, functional results were excellent in four (57%) and improved in three. For the nonpatent graft, the function was not improved. Patent vein grafts restored the pulse volume recording amplitudes in painful digits to normal in six of seven cases, although slow rewarming after ice immersion suggested residual vasospastic disease in two. The most favorable outcomes were in (1) nonsmokers, with (2) a single, distinctly recalled history of trauma to the palm, and (3) preoperative symptoms of less than 5 months' duration before treatment. Interposition vein grafts can be used to restore pulsatile digital blood flow to painful digits after thrombosis of the ulnar artery.

Adult↗

PubMed1991

End-to-side-anastomosis in the dog using the 3M precise microvascular anastomotic system: a comparative study.

In this study, the patency rates, microscopic characteristics, and intraluminal dimensions of end-to-side anastomoses in the dog were compared with those of a conventional interrupted suturing technique, using the 3M precise microvascular anastomotic system. The anastomoses included end-to-side repairs of the saphenous artery to the femoral artery, as well as the saphenous vein to the femoral vein. The patency and microscopic characteristics of the two techniques were similar, but the mechanical coupling system required much less time than the suture technique to complete the vascular anastomosis.

Anastomosis, Surgical↗

PubMed1991

Regional anesthesia of the hand for dermatologic surgery.

The basic principles of regional and local anesthesia of the hand are reviewed, and safe and effective methods for outpatient dermatologic procedures and three representative cases are discussed with respect to anatomy, local anesthetic agents, and techniques. Block techniques are preferred to local infiltration because they provide complete and long-lasting anesthesia more comfortably.

Adult↗

PubMed1991

Peroneal nerve repair. Surgical results.

Eleven patients had either repair (two) or nerve graft reconstruction (nine) of the common peroneal nerve or its superficial or deep divisions about the knee. The average follow-up period was 29.1 months. A good or excellent result was achieved in six (54.5%) patients. The results appeared best when direct nerve repair was possible or when a defect of 6 cm or less required grafting. Peroneal nerve exploration and repair or reconstruction as required seem indicated for known nerve disruption or unknown nerve continuity if there is no suggestion of continuing recovery by three to six months after the injury.

Adolescent↗

PubMed1990

Blood flow evaluation of vascularized bone transfers in a canine model.

Blood flow in vascularized bone transfers was evaluated in a canine model. Cortical bone blood flow was determined in undisturbed control bone, vascularized heterotopic bone transfers, and nonvascularized cortical bone grafts by means of the radionuclide-labeled microsphere technique. Four animals were studied at 2 days, three at 1 week, eight at 2 weeks, four at 4 weeks, and three at 6 weeks postoperatively. In the 2-day animals, the vascularized bone transfers exhibited intermediate levels of blood flow (1.4 +/- 0.4 ml/100 g of bone/min) compared with undisturbed control bone (2.7 +/- 0.5 ml/100 g of bone/min) and conventional cortical bone grafts (0.0 +/- 0.0 ml/100 g of bone/min). At 1 week postoperatively, the differences in blood flow values of the vascularized transfers (1.7 +/- 0.7 ml/100 g of bone/min) and control bone (1.4 +/- 1.0 ml/100 g of bone/min) and of the nonvascularized grafts (0.2 +/- 0.1 ml/100 g of bone/min) and control bone (1.6 +/- 1.1 ml/100 g of bone/min) were no longer significant. At 2 weeks postoperatively, blood flow had increased in both graft groups. At 4 weeks postoperatively, the bone blood flow values in the vascularized transfers (4.8 +/- 1.4 ml/100 g of bone/min) were significantly greater than the bone blood flow in control specimens (1.6 +/- 0.5 ml/100 g of bone/min) and conventional cortical bone grafts (2.5 +/- 2.0 ml/100 g of bone/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗