Biomedical subjects

J W Shaffer

Publications and source records attributed to J W Shaffer.

At least 19 recordsLinked to original sources

PubMed1998

Histopathologic analysis of failed vascularized fibular grafts in femoral head osteonecrosis.

Salient histopathological features in 13 failed free vascularized fibular autografts implanted for osteonecrosis of the femoral head are documented. Of particular clinical and/or biomechanical relevance are 1-2-mm-thick seams of viable lamellar bone bonded circumferentially to anatomically intact but necrotic graft cortices, which appear to preclude their revascularization and remodeling. Surrounding the grafts are 3-6-mm-thick rings of reactive bone, fused in many sites (average approximately 54%) to the osseous seams. They consist of a layer of sclerotic cortical-like bone melded with an outer layer of thickened cancellous bone. This remodeled reactive bone, largely the result of drilling, appears to buttress the grafts structurally and by inference, functionally. Operative failures in all but one case are attributed primarily to collapse of the necrotic, fractured superior subtending segment of the graft and of the subchondral plate secondary to size and progression of the osteonecrosis and superimposed osteoarthrosis. Morphological integrity of grafts elsewhere and perifibular reactive sclerotic bone remain unimpaired for up to 5 1/2 years. The salutary features of vascularized autografts would appear to give them a decided advantage over their nonvascularized counterpart.

Adult↗

PubMed1996

The humoral response to vascular and nonvascular allografts of bone.

The cytotoxic donor specific antibody response after vascularized and nonvascularized bone allograft implantation was assessed in rats and dogs. Nonvascularized segmental femoral grafts were studied in rats; nonvascularized fresh and cryopreserved massive osteochondral allografts were studied in dogs; and vascularized and nonvascularized fibular allografts were studied in dogs. The major histocompatibility complex antigens of all animals were defined. All grafts were stabilized by internal fixation and the antibody response was measured in a 51chromium release microcytotoxicity assay using donor lymphocytes as target cells. In all cases, donor specific antibody responses were elicited by major histocompatibility complex mismatched grafts. The response was directed primarily at Class I specificities although there was likely and antiClass II response as well. Among fully mismatched grafts, antidonor antibody was detectable earlier in animals receiving vascularized grafts (1 week after surgery) than in animals receiving nonvascularized grafts (3 weeks after surgery). Massive grafts elicited a sustained response whereas relatively smaller grafts, such as the fibula did not. The antidonor antigen antibody response was transient and less frequent in animals receiving frozen grafts. The clinical implications of these data are unclear. Although some improvement of clinical outcome has been observed with grafts matched for major histocompatibility complex antigens, the potential benefits of tissue antigen matching or modulation of the host immune response remain unresolved.

Animals↗

PubMed1995

Functional range of motion of the elbow.

One hundred normal upper extremities in 50 adults were sequentially studied in a Bledsoe brace, which limited elbow motion. The amount of flexion and extension of the elbow was serially limited by 15 degree increments. At each setting, the subjects were asked to perform 12 activities of daily living. The percentage of subjects who completed each task with the specified range of motion was determined. Overall, 49 of the subjects performed all of the tasks with extension limited at 75 degrees and flexion limited at 120 degrees. By isolating the allowable range of motion of the elbow and allowing for compensatory motions and strategies of the normal adjacent joints, the functional elbow range of motion is established as 75 degrees-120 degrees flexion. Thus, the functional status of a patient with a specific elbow range of motion can be predicted more accurately.

Activities of Daily Living↗

PubMed1994

Suprascapular nerve injury during spine surgery. A case report.

In long spine surgeries, knee-chest position-associated complications can occur. This report describes a case of suprascapular nerve injury that occurred during the lengthy surgical procedure. It is postulated that excessive scapula, shoulder girdle, and upper arm protraction occurred, resulting in a sling effect compression injury of the suprascapular nerve.

Adult↗

PubMed1993

Experimental microsurgical vein grafts: quantitative temporal analysis of progressive media fibroplasia.

The sequential histopathologic changes in microvenous grafts placed in a microarterial system were studied. In 48 Sprague Dawley rats, a 1 cm segment of epigastric vein was interposed into a defect created in the femoral artery. Grafts were explored at 1, 2, 4, and 12 weeks. After an initial smooth muscle hyperplasia, a progressive fibroplasia of the media was observed. Only small focal areas of intimal hyperplasia were seen. The width of the media was measured with an eyepiece micrometer. A statistically significant (P < 0.01) increase in width from 17 microns at 1 week to 462 microns at 12 weeks was noted. Although this process has been described before, this is the first quantitative assessment.

Anastomosis, Surgical↗

PubMed1992

The effects of vascularity and cyclosporin A on the mechanical properties of canine fibular autografts.

We studied the biomechanical behavior of orthotopic canine autografts as influenced by vascularized supply and the administration of cyclosporin A at three months and six months post-surgery. The model was the proximal 8 cm of the fibula in young adult dogs. In vascularized grafts, blood supply was re-established by microvascular re-anastomosis. Experimental controls were sham-operated and unoperated bones. Mid-graft test sections were subjected to loading-to-failure in torsion to determine the strength and stiffness. In both three- and six-month groups, vascularized grafts were significantly stronger and stiffer than contralateral nonvascularized grafts. Vascularized grafts were not significantly different from sham-operated bones. A 30-day regimen of cyclosporin A was found to have no measurable effect on mechanical properties for any individual treatment group. The results indicate that re-established blood supply can be a major factor in maintaining the mechanical integrity in large-segment cortical autografts.

Animals↗

PubMed1991

Bone mass and comparative rates of bone resorption and formation of fibular autografts: comparison of vascular and nonvascular grafts in dogs.

The metabolic fate of whole grafts that were either vascularized or nonvascularized were compared. This study was designed to quantify and correlate changes in bone resorption, formation, and mass in orthotopic, stably fixed, weight-bearing autografts. The grafts were 8-cm segments of the fibula that were internally fixed. Fibula segments subjected to sham operations, nonvascularized autografts, and vascularized autografts were studied in 16 dogs at three months after surgery. Three months prior to surgery the dogs were labeled repeatedly over two months with 3H-tetracycline and 3H-proline. Metabolic turnover of whole grafts was evaluated by quantifying loss of 3H-tetracycline for measuring postoperative resorption of bone mineral and loss of 3H-collagen for resorption of bone collagen. Net changes in bone dry weight, calcium, and collagen per whole grafts were obtained to determine differential changes in the mineral and matrix mass. The difference in change between bone resorption and bone mass was used to determine the amount of new bone formation that had replaced the resorbed bone. Vascularized autografts lost more mass (12%), and had more bone resorption (40%) and more bone formation (28%) than sham operated and unoperated fibulas. Nonvascularized grafts lost much more bone mass (48%) because resorption was large (61%) and formation was relatively small (13%). More new bone was formed in vascularized autografts than in nonvascularized autografts. During the incorporation of bone grafts, resorption is an early and rapid process, whereas formation is a late and slow process.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Development of collateral circulation in a replanted rat hindlimb model.

The development of collateral circulation was studied in a replanted rat hindlimb model by use of the hemodynamic techniques of hydrogen washout and laser Doppler capillary perfusion monitoring. Collateral development occurred and provided blood flow whose magnitude increased linearly over time. Twenty-seven percent of preligation blood flow was present at 2 weeks after replantation, 39% at 4 to 5 weeks, and 77% at 8 to 9 weeks by laser Doppler assessment. Laser Doppler correlated more closely with limb survival than did the hydrogen washout technique. Uniform necrosis (eight of eight) occurred after pedicle interruption in the 2-week group. Partial limb survival was noted in five of eight replants at 4 to 5 weeks on transection of the vascular pedicle, while complete survival of all replants (nine of nine) was seen at 8 to 9 weeks.

Animals↗

PubMed1991

Differential patterns of incorporation and remodeling among various types of bone grafts.

The early (3 months) and later (6 months) patterns of incorporation and bone formation have been evaluated histomorphometrically for different types of bone grafts; that is, vascularized and nonvascularized autografts with and without ciclosporin, and vascularized and nonvascularized dog leukocyte antigen (DLA)-mismatched allografts with and without ciclosporin. The vascularized bones were superior to the nonvascularized ones in healing and remodeling their grafted segments. In the autograft bones, ciclosporin did not alter the incorporation process 3 months after transplantation but delayed and increased the remodeling activities in the long run (6 months). Nonvascularized allografts underwent vigorous resorption, and were markedly porotic. Ciclosporin administration significantly reduced resorption and enhanced remodeling in nonvascularized allografts. The remodeling of allografts was similar to that of autografts in the presence of ciclosporin, but stopped soon after the administration of ciclosporin ceased.

Animals↗

PubMed1990

Cyclosporin A and tissue antigen matching in bone transplantation. Fibular allografts studied in the dog.

We studied the mechanical, metabolic, and histologic properties of short-term nonvascularized cortical bone grafts in a canine fibular graft model. Sham operated nonvascularized autotransplanted and allotransplanted bones were compared. The allografts were performed between dog leukocyte antigen (DLA) class I and II matched; DLA class I and II mismatched; and cyclosporin A (CsA) treated, DLA class I and II mismatched animals. Cyclosporin was given for 1 month, and all the animals were followed for 3 months after surgery. Mechanical properties were investigated using standard torsional tests, metabolic kinetics were assessed using isotopic prelabeling techniques, and histomorphometric analysis of cross-sectional area properties and sequential fluorochrome labels were performed. Autografts were mechanically stronger and stiffer than all the types of allograft. CsA-treated, DLA-mismatched allografts performed better than matched allografts. These in turn were stronger than non-CsA-treated, mismatched allografts, which underwent nearly complete resorption. These relationships were preserved in the metabolic and histologic analyses. In this short-term animal study, although DLA matching resulted in a slight improvement in graft outcome, mismatched grafts in dogs receiving a short course of cyclosporin A fared even better.

Animals↗

PubMed1990

Biological and physical properties of autogenous vascularized fibular grafts in dogs.

The biological and biomechanical properties of normal fibulae, fibulae that had had a sham operation, and both vascularized and non-vascularized autogenous grafts were studied in dogs at three months after the operation. The study was designed to quantify and correlate changes in these properties in orthotopic, stably fixed, weight-bearing grafts and to provide a baseline for additional studies of allografts. The grafts were eight centimeters long and internally fixed. The mechanical properties of the grafts were studied by torsional testing. Metabolic turnover of the grafts was evaluated by preoperative labeling of the dogs with 3H-tetracycline for resorption of bone mineral and with 3H-proline for turnover of collagen. Cortical bone area and porosity were measured. Postoperative formation of bone was evaluated by sequential labeling with fluorochrome. The vascularized grafts resembled the fibulae that had had a sham operation and those that had not had an operation with regard to the total number of osteons and the remodeling process, as measured both morphometrically and metabolically. The vascularized grafts were stronger and stiffer than the non-vascularized grafts and were not different from the bones that had had a sham operation. In contrast, the non-vascularized grafts were smaller, weaker, less stiff, and more porotic, had fewer osteons, and demonstrated increased turnover and resorption compared with the vascularized grafts, the bones that had had a sham operation, and the bones that had not been operated on.

Animals↗

PubMed1989

Effects of halothane, enflurane, and isoflurane in nitrous oxide on multilevel somatosensory evoked potentials.

The effects of halothane, enflurane, and isoflurane were studied at 0.5, 0.75, and 1 MAC in 60% N2O on subcortical sensory evoked potentials recorded at the popliteal fossa (PF), the spine (L-3, C-6) and on cortical potentials recorded at the scalp (SC) following bilateral posterior tibial nerve stimulations at the ankle in 28 patients undergoing scoliosis surgery. Latencies and amplitudes of the resulting potentials at each level were compared with postinduction control values. With increasing MAC, latency and amplitude changes seen at C6 (subcortical) were also compared with those at SC (cortical). Increasing the concentrations of each agent resulted in a graded increase in latency and a graded decrease in amplitude, at all levels. At SC each increase in MAC with each agent resulted in an increase in latency (P less than 0.05) and a decrease in amplitude (P less than 0.005), respectively. The increases in SC latency at 0.75, 1 MAC were larger than the increase in latency at C-6 (P less than 0.005) and the decreases in SC amplitudes at 0.5, 0.75 and 1 MAC were greater than the decrease in amplitude at C-6 (P less than 0.01). Halothane, enflurane, and isoflurane in 60% N2O altered subcortical potentials less than cortical potentials. Enflurane and isoflurane at 0.5, 0.75, and 1 MAC, and halothane at 0.5, 0.75 MAC maintained subcortical and cortical potentials that were adequate for evaluation. However, 1 MAC of halothane suppressed cortical potentials but maintained subcortical potentials. Subcortical C-6 potential may serve as an additional monitor.

Adolescent↗

PubMed1989

Temporal analysis of vascularized and nonvascularized rib grafts in canine spine surgery.

The authors have previously reported work demonstrating the superiority of vascularized vs. nonvascularized rib grafts, which were inlaid to bridge three vertebral bodies studied at 3 months postoperatively. They questioned whether the mechanical and biologic properties of the nonvascular grafts would improve over time to approach the performance of the vascularized grafts by 6 months. They found that, with increased time, the vascularized grafts continued to improve, showing hypertrophy, maintenance of cortical integrity, and bonding to the recipient vertebral bodies. The nonvascularized grafts, however, showed porosity, fragmentation, and replacement by spongiosa. Mechanical properties showed increased performance in the vascularized vs. nonvascularized grafts, and no improvement was seen between the nonvascularized grafts from 3 to 6 months.

Animals↗

PubMed1988

MMPI-168 profiles of male narcotic addicts by ethnic group and city.

MMPI-168 profiles were obtained on 225 male narcotic addicts who were attending methadone maintenance clinics in Baltimore and New York City during 1983 and 1984. Data were collected on Black and White (Anglo, other than Hispanic) addicts in Baltimore and on Black, Hispanic, and White addicts in New York City. In general, the profiles indicated high levels of psychopathology, with particularly high elevations on the F, D, PD, PT, and Sc scales. Consistent across cities and in agreement with earlier findings, profiles of Whites indicated somewhat more maladjustment than those for Blacks, while the profiles of Hispanics displayed essentially the same levels of disturbance as those for Whites. Comparisons by city revealed greater deviance for New York City subjects, a finding more evident among Whites than among Blacks.

Ethnicity↗

PubMed1988

Treatment of experimental frostbite with urokinase.

An experimental model of frostbite using a standard cold injury in rats was used to test the therapeutic usefulness of the fibrinolytic agent urokinase. Control groups included rapid rewarming, slow rewarming, and slow rewarming followed by saline infusion. Urokinase was administered through an intra-arterial catheter 30 minutes after cold injury and slow rewarming. Optimum results were obtained with rapid rewarming of the extremity at 43 degrees C. However, with rewarming at room temperature eventual tissue loss was significantly decreased with the infusion of urokinase compared with either no treatment or saline infusion. In the clinical situation where the patient with frostbite is seen after slow rewarming, we believe that clinical trials of the use of a fibrinolytic agent are warranted.

Animals↗

PubMed1988

Differences among treatment clinic types in attitudes toward narcotic addiction.

Factor analysis of data from a general survey of attitudes and opinions concerning narcotic addiction and its treatment revealed 10 major dimensions, five of which were likely to have significant implications for drug abuse intervention strategies. For these latter dimensions, differences were determined among clients and staff according to type of treatment clinic (three types involving the provision of methadone maintenance in various combinations with other treatments and one involving the use of abstinence only). The most pronounced differences were between the methadone clinics and those offering abstinence only. Both the clients and staff of abstinence clinics were more skeptical concerning treatment effectiveness, were more negative regarding the use of narcotic drugs, and were more disposed to the use of ex-addict counselors and group procedures in treatment.

Black or African American↗

PubMed1988

The superiority of vascularized compared to nonvascularized rib grafts in spine surgery shown by biological and physical methods.

Eleven canine experiments were performed to demonstrate the advantages of immediate vascular preservation in ribs used to fill a surgically created osseous gap bridging three vertebral bodies. In the five vascular rib grafts, mean blood flow was retained and measured at .101/ml/min/ml bone tissue. At autopsy 3 months post-operatively, vascularized grafts were more robust and hypertrophic. Mechanical testing in six stiffness modes confirmed the advantage of vascularized grafts. The experimental results indicate that vascularized grafts retain greater viability and better mechanical properties during graft incorporation. Providing a vascularized construct may be helpful in reconstructing large vertebral osseous gaps.

Animals↗

PubMed1988

The healing of canine vascularized segmental tibial osteotomies. The effect of retained endosteal circulation.

Forty-eight pairs of canine tibial segmental osteotomies, 4 cm in length, were investigated to determine the progress of regeneration. The tibial segment was stripped of all soft tissue in one limb and the vascular pedicle was preserved in the contralateral limb. This allowed the healing of the tibial segments, vascular versus nonvascular, to be compared using sequential blood flow and roentgenographic and angiographic data. The blood flow to the vascular bone segment quadrupled at three weeks and then gradually decreased to 1.5 times baseline at one year. The nonvascular tibial segment showed a linear increase in flow for three months, achieving a level comparable to the contralateral vascular tibia segment. Peak flow in the vascular tibia at three weeks was four times that of the nonvascular tibia. Blood-vessel ingrowth from each osteotomy site progressed at a linear rate but was three times faster in the vascular bone. The deposition of callus and the rate of osteotomy healing were accelerated significantly in the vascular group. At three months 87% of the vascular tibial osteotomies healed versus 43% of the nonvascular osteotomies; these results represent significant advantages in the rate of healing in vascular versus nonvascular segmental tibial osteotomies. Segmental vascular bone grafts that are internally fixed with plate and screws can preserve the vascular structure and its advantages in bone regeneration.

Angiography↗