Biomedical subjects

Allen T Bishop

Publications and source records attributed to Allen T Bishop.

34 records · Page 2Linked to original sources

PubMed2004

Restoration of motor function of the deep fibular (peroneal) nerve by direct nerve transfer of branches from the tibial nerve: an anatomical study.

Traction injuries of the common fibular (peroneal) nerve frequently result in significant morbidity due to tibialis anterior muscle paralysis and the associated loss of ankle dorsiflexion. Because current treatment options are often unsuccessful or unsatisfactory, other treatment approaches need to be explored. In this investigation, the anatomical feasibility of an alternative option, consisting of nerve transfer of motor branches from the tibial nerve to the deep fibular nerve, was studied. In ten cadaveric limbs, the branching pattern, length, and diameter of motor branches of the tibial nerve in the proximal leg were characterized; nerve transfer of each of these motor branches was then simulated to the proximal deep fibular nerve. A consistent, reproducible pattern of tibial nerve innervation was seen with minor variability. Branches to the flexor hallucis longus and flexor digitorum longus muscles were determined to be adequate, based on their branch point, branch pattern, and length, for direct nerve transfer in all specimens. Other branches, including those to the tibialis posterior, popliteus, gastrocnemius, and soleus muscles were not consistently adequate for direct nerve transfer for injuries extending to the bifurcation of the common fibular nerve or distal to it. For neuromas of the common fibular nerve that do not extend as far distally, branches to the soleus and lateral head of the gastrocnemius may be adequate for direct transfer if the intramuscular portions of these nerves are dissected. This study confirms the anatomical feasibility of direct nerve transfer using nerves to toe-flexor muscles as a treatment option to restore ankle dorsiflexion in cases of common fibular nerve injury.

Adult↗

PubMed2004

VEGF-promoted surgical angiogenesis in necrotic bone.

The ability of vascular endothelial growth factor (VEGF) to accelerate neoangiogenesis from implanted arterovenous (AV) bundles in necrotic bone was evaluated. A saphenous AV bundle was placed in a necrotic segment of rabbit ilium. In group II, VEGF (100 ng/h x 3 days) was administered by continuous infusion. Bone blood flow was measured with radioactive-labeled microspheres, and capillary density was determined by microangiography combined with Spälteholtz bone clearing at 1, 2, and 4 weeks. Neovascularization was observed along the implanted vascular bundle in both groups. One week after surgery, bone blood flow and vessel area were significantly higher in VEGF-treated animals (P < 0.05). No significant difference was observed at later times. Direct VEGF administration increased surgical angiogenesis and improved blood flow and neovascularization in necrotic bone 1 week after AV bundle implantation. Thereafter, a robust angiogenic response from the AV bundle was seen in both groups.

Animals↗

PubMed2004

Arthroscopic resection in the management of dorsal wrist ganglions: results with a minimum 2-year follow-up period.

PURPOSE: The purpose of this report is to review the results of arthroscopic resection of dorsal wrist ganglions. METHODS: Forty-one patients with dorsal wrist ganglions had arthroscopic resection: 24 women and 17 men. The average patient age was 29.8 years. All of the patients had some or all of the following: pain, localized swelling, and limited range of motion. Along with clinical examination, 19 wrists had ultrasound or magnetic resonance imaging to confirm diagnosis. Twelve patients had previous injections with recurrence. The average follow-up time to date is 47.8 months (range, 28-97 months). RESULTS: Overall postoperative motion improved compared with preoperative values. No cases of scapholunate instability were noted. The average postoperative grip strength improved significantly. Only 2 ganglions recurred and required 2 attempts at open resection for successful eradication the ganglion. No major intraoperative or postoperative complications occurred. CONCLUSION: Arthroscopic ganglionectomy is a safe and reliable alternative to open resection.

Adolescent↗

PubMed2004

Transduction of rabbit saphenous artery: a comparison of naked DNA, liposome complexes, and adenovirus vectors.

The methods and efficiency of gene transfer into rabbit saphenous artery were examined in this study. The purpose was to develop an animal model capable of evaluating the use of angiogenic gene therapy to revascularize necrotic bone more rapidly and completely than by surgical implantation of blood vessels alone. The success of transduction using adenovirus vectors, liposome/DNA complexes, and naked DNA was evaluated with delivery to both intra-luminal and adventitial sites. Intra-luminal and adventitial (extra-luminal) application was used for the viral and liposome methods. Naked DNA was evaluated only in the intra-luminal site, based upon previous reports. Relative transduction success was expressed as the percentage of total cells with beta-galactosidase activity. A 20-mm length of saphenous artery exposed surgically was targeted for lacZ gene transfer. Two days after transduction, the arteries were harvested and stained with X-gal for beta-galactosidase activity. The percentage of endothelial, media and adventitial cells with beta-galactosidase activity was determined. Intra-arterial injection of adenovirus vector transduced the largest amount of cells in all three areas of the vessel (endothelium, media and adventitia). The adenovirus vectors when applied to the adventitia only transduced adventitial cells. Following intra-arterial injection of liposome/DNA complexes transduction was detected only in endothelium. Extra-luminal liposome and intra-arterial naked DNA delivery resulted in no detectable gene transfer. Intra-arterial delivery of an adenovirus vector would likely provide optimal gene transfer for possible angiogenic gene therapy.

Adenoviridae↗

PubMed2003

Mycobacterium marinum infections of the distal upper extremities: clinical course and imaging findings in two cases with delayed diagnosis.

Mycobacterium marinum infections cause tenosynovitis of the distal upper extremities and develop as a consequence of skin abrasions acquired in contaminated water. We report on two patients whose MR imaging studies showed tenosynovitis of the distal upper extremity secondary to M. marinum. In one patient sequential MR imaging showed development of bony erosions. Appropriate treatment was delayed in both patients because the diagnosis was not considered. We report on and discuss the clinical course and MR imaging findings in two patients with M. marinum infection.

Adult↗

PubMed2003

Detection of chimerism following vascularized bone allotransplantation by polymerase chain reaction using a Y-chromosome specific primer.

Chimerism following allogeneic organ transplantation is a phenomenon known to occur and be associated with development of immunologic tolerance in allotransplantation. However, little is known about graft cell migration following vascularized bone allografting. In this study, chimerism was assessed following vascularized tibia transplantation from male DA or PVG donors to female PVG rat recipients using a semi-quantitative polymerase chain reaction for the Y-chromosome. FK-506 (Tacrolimus) was administered after transplantation for immunosuppression. All immunosuppresssed PVG rat recipients of PVG bone grafts showed a high level of chimerism (1%) in the thymus, spleen, liver and cervical lymph nodes at 18 weeks post-transplant. Donor cells were also detected in the contralateral tibia and humerus. In non-immunosuppressed PVG rat recipients of DA bone grafts, donor cells were detected in the spleen in three of five rats within 2 weeks post-transplant. In these animals the bone grafts were severely rejected. In immunosuppressed PVG rat recipients of DA bone grafts, two of five, four of eight and eight of 10 rats showed low level chimerism (0.1%) in peripheral blood at 1, 12, and 18 weeks post-transplant. Six rats showed a high level of chimerism in the spleen and thymus. Histological studies revealed no rejection findings through 18 weeks post-transplant. Our results indicate that chimerism, or the presence of graft cells in host tissue, may occur in the face of acute rejection and be demonstrable following vascularized isograft and allograft living bone transplantation when chronic immunosuppression is maintained. Graft vascular patency during the short-term likely allows cellular migration, even in the face of acute rejection. Long-term survival and proliferation of graft marrow elements in host tissue may be possible with adequate immunosuppression.

Animals↗

PubMed2003

Extension block pinning for large mallet fractures.

PURPOSE: The purpose of this report is to review the results of displaced mallet fractures treated with an extension block pin and transarticular fixation of the distal interphalangeal joint. METHODS: We retrospectively reviewed 23 patients with 24 fractures to determine the results of treatment, time to union, range of motion, and associated complications. RESULTS: The average patient age was 24 years and the average fracture size was 40% of the joint surface. Ten patients were treated acutely (less than 10 days), 10 subacutely (10-30 days), and 3 chronically (greater than 30 days). Average time to fracture union was 35 days. At 1-year or greater follow-up evaluation the average extension loss was 4 degrees and the average flexion was 77 degrees. There were no major complications and there were 5 minor complications. Using the established outcome criteria for mallet injuries, 92% had excellent or good results. CONCLUSIONS: The results of this study showed that this surgical technique resulted in rapid fracture union with only minor complications and has excellent functional outcome based on established criteria.

Adult↗

PubMed2003

Fate of donor cells in vascularized bone grafts: identification of systemic chimerism by the polymerase chain reaction.

Systemic chimerism, or the movement of cells from a transplanted tissue into host organs, is a phenomenon known to occur in association with development of immunological tolerance in allotransplantation. However, little is known about the fate and movement of cells into or out of autogenous free tissue transfers, including vascularized bone grafts. The purpose of this study was to identify systemic chimerism in vascularized bone grafts by transplantation of a vascularized tibiofibular graft from isogenous (inbred) male Lewis rats to female recipients. Donor (male) cells could be identified in the recipient (female) tissues by semiquantitative polymerase chain reaction analysis for a Y chromosome-specific DNA sequence. Chimerism was assessed at 1, 12, 18, and 24 weeks after transplantation. Competitive polymerase chain reaction study using the specific primers for a Y-chromosome marker ( gene) and an autosomal gene (GAPDH) allowed detection of small amounts of male cells in a large pool of female cells and measurement of their relative proportions as a function of time. Of 19 nonimmunosuppressed recipients, nine animals (47 percent) showed low-level chimerism (<0.1 percent) in the peripheral blood. Nine (47 percent), three (16 percent), and two (11 percent) recipients showed high-level chimerism (>1 percent) in the spleen, liver, and thymus, respectively, at final assessment. Donor cells were detected in all bone grafts and in six contralateral tibial bones (i.e., 67 percent of sampled contralateral tibial bones) at 18 and 24 weeks after transplantation. Twenty-four recipients were immunosuppressed with FK506 (tacrolimus) to suppress reaction to a minor histocompatibility barrier present on the Y chromosome. In this group, 14 animals (58 percent) showed low-level chimerism in peripheral blood and 12 (50 percent), eight (33 percent), and one (4 percent) recipients showed high-level chimerism in the spleen, thymus, and liver, respectively. Transplanted cells were detected in nine contralateral tibial bones (i.e., 60 percent of sampled contralateral tibial bones) at 12 and 18 weeks after surgery. The results indicate that polymerase chain reaction for the Y chromosome is a useful tool for differentiating between donor and recipient cell populations experimentally using sex-mismatched tissues in a rat model. This study demonstrated that systemic chimerism occurs after successful vascularized bone transplantation. Transplanted cells not only survive in the graft but also gradually migrate into the recipient's body.

Animals↗

PubMed2002

Detection of the proliferated donor cells in bone grafts in rats, using a PCR for a Y-chromosome-specific gene.

Conventional corticocancellous bone grafts are known to revascularize gradually and to become repopulated with osteocytes and other types of cells. This study was conducted to study the origin of the cells found within conventional bone grafts as a function of time, using a new method which accurately identifies donor cells transplanted with the graft. The technique requires the transplantation of a 25-mm tibial diaphyseal bone graft from a male rat to a female isogenous recipient, placed anatomically in the tibia. The presence and relative proportion of cells containing the Y-chromosome (i.e., originating from the bone graft) was determined 4, 8, and 12 weeks after transplantation. At these times, genomic DNA was extracted from the grafted bones and a polymerase chain reaction (PCR) specific for the sex-determining region of the Y-chromosome (Sry) was performed, with appropriate controls. Sry-specific bands were evident in none out of three grafts at 4 weeks, two out of three at 8 weeks, and all grafts at 12 weeks. These data demonstrate that not all cells within a conventional graft result from "creeping substitution" of necrotic bone. Instead, a small number of intrinsic cells from a nonvascularized corticocancellous structural graft survive and proliferate over time.

Animals↗

PubMed2002

Cell repopulation in vascularized bone grafts.

Following vascularized bone autografts, osteocyte viability is largely maintained. Viable cells within a graft may be surviving graft-derived cells, their progeny, or host-derived cells from circulation or surrounding bone. This study was conducted to define the process of cell repopulation, within vascularized bone grafts. Using inbred Lewis rats, 30 female vascularized tibial bones were transplanted to syngeneic male recipients and 45 male grafts were transplanted to female recipients. Twenty-five female recipients were immunosuppressed with FK506 to prevent rejection caused by Y-chromosome related antigens. The grafts were assessed up to 24 weeks post-transplant by radiography, histology and semi-quantitative polymerase chain reaction (PCR) using both Y-chromosome and autosome gene-specific primers. The female to male isograft transplants were useful to measure low levels of repopulation with host-derived cells, while male to female transplants more accurately quantified higher levels of cellular replacement. No host-derived cells were detected in the transplanted bone before six weeks. Thereafter, the ratio of host-derived cells gradually increased. By 24 weeks only 0.1-1.0% of graft-derived cells remained in the transplanted tibias. This study demonstrates that Y-chromosome-specific PCR is a useful tool to detect the cell lineage and cell repopulation following rat sex-mismatch vascularized bone grafting. Our results showed that donor cells in vascularized bone grafts were gradually repopulated with recipient cells. Correlation with histologic findings suggests that the periosteal hypertrophy observed by six weeks post-transplant results from graft-derived cells, while later remodeling is associated with host-derived cells.

Animals↗

PubMed2002

Vascular endothelial growth factor promotion of neoangiogenesis in conventional nerve grafts.

The effect of vascular endothelial growth factor (VEGF) on angiogenesis and neovascularization of conventional nerve grafts was evaluated in 48 rabbits. A 2.5-cm segment of right sciatic nerve was removed and orthotopically repaired. This graft was wrapped in dialysis tubing to prevent vessel ingrowth from adjacent tissue. An osmotic pump delivered either VEGF (100 ng/h for 3 days) or control solution. Evaluation methods included angiography, vessel density, and nerve blood flow measurement at 3, 7, and 14 days. On day 3, 42% of the control nerves and 100% of VEGF-treated nerves had partial longitudinal neovascularization. Vessel density (0.84 +/- 0.22 vessel/mm(2)) and nerve blood flow [25.34 +/- 7.62 mL/(min.100 g)] in VEGF-treated nerves were significantly higher than control group values [0.23 +/- 0.13 vessel/mm(2) and 5.35 +/- 0.99 mL/(min.100 g)]. Progressive improvement in parameters was seen at 7 and 14 days. Vascular endothelial growth factor infusion accelerates longitudinal neoangiogenesis and shortens the nerve ischemic time to 3 days in this model. The revascularization of VEGF-treated conventional nerve grafts in a poorly vascularized bed is identical to that of grafts in a healthy bed.

Animals↗

PubMed2002

Use of the 1,2 intercompartmental supraretinacular artery as a vascularized pedicle bone graft for difficult scaphoid nonunion.

Fourteen patients with established scaphoid nonunion were treated with vascularized pedicle bone grafting. All nonunions healed at a mean of 11.1 weeks (range, 8-16 weeks). Wrist motion was minimally affected by surgery. Intercarpal and scaphoid angles were improved after surgery, particularly in patients with preoperative humpback deformity who had previous interposition grafting. Outcome, based on a self-assessment questionnaire administered at a mean 30 months of follow-up (range, 19-53 months), showed 2 excellent, 7 good, 4 fair, and 1 poor result. Three patients showed progressive radioscaphoid arthrosis. Vascularized bone grafts are indicated in proximal pole fracture nonunions, in the presence of avascular necrosis, and after conventional grafts. Radiocarpal arthritis, if present before surgery, is a poor prognostic sign.

Adolescent↗

PubMed2002

Extension-block pinning for treatment of displaced mallet fractures.

Mallet injuries are common in active individuals, particularly those who participate in sports such as basketball and football. Although a majority of patients with displaced mallet fractures are treated conservatively with extension splinting, their treatment is often complicated by residual loss of extension and fracture displacement secondary to unfavorable fracture biomechanics and poor patient compliance. An attractive alternative to nonoperative treatment is the minimally invasive technique of extension-block percutaneous pinning. Extension-block percutaneous pinning allows anatomic restoration of the articular surfaces and avoids the complications associated with closed treatment. The technique is easy to perform and is an effective, safe alternative to the conservative treatment of displaced mallet fractures, particularly those associated with joint subluxation.

Athletic Injuries↗

PubMedDate not supplied

Hand span and digital motion on the keyboard: concerns of overuse syndrome in musicians.

PURPOSE: To investigate the hand motion of pianists when they performed an octave and a chord, which accounted for 74% of the piano techniques that the subjects practiced at the onset of overuse hand problems. The octave position was to strike 2 keys that were 16.7 cm apart simultaneously with the thumb and small finger, and the chord position was to strike 3 keys with 4.8 cm between the borders. METHODS: The abduction angle of both the thumbs and the small fingers of 10 pianists while playing a chord and an octave were measured repeatedly with a video-based passive marker detection system. The angles were compared between pianists with large hand spans and those with small hand spans. RESULTS: When playing the octave both the maximal and minimal abduction angles of the thumb were significantly larger for the smaller-hand pianists as compared with the pianists with larger hand spans. When playing the chord the maximal abduction angle of the thumb of small-hand-span pianists was significantly larger than that of large-hand-span pianists. The abduction of the small finger, however, did not differ during performance of either the octave or the chord. CONCLUSIONS: These results suggest that the small-hand-span pianists must abduct the thumb more than large-hand-span pianists while minimizing movement of the small finger. This may cause de Quervain's tenosynovitis in pianists.

Adult↗

PubMedDate not supplied

Free vascularized corticoperiosteal bone graft for the treatment of persistent nonunion of the clavicle.

Radiation-induced necrosis or infection can result in a persistent nonunion of the clavicle. We describe 3 cases in which a free vascularized corticoperiosteal flap was harvested from the medial aspect of the femoral condyle and transferred to the fractured clavicle by use of microvascular anastomoses. Healing was confirmed by tomography in all 3 patients. The function of the upper extremity was remarkably improved at final follow-up. Vascularized free corticoperiosteal bone flaps are an option in clavicle fracture treatment. The technique of periosteal grafting is ideally suited to chronic nonunions with poor chances of healing on their own. Rapid subperiosteal new bone and improved local blood flow serve to correct many of those changes attributed to necrosis of bone.

Adult↗

PubMedDate not supplied

Pedicled vascularized bone grafts for disorders of the carpus: scaphoid nonunion and Kienbock's disease.

The use of reverse-flow pedicled vascularized bone grafts from the dorsal distal radius makes it possible to transfer bone with a preserved circulation and viable osteoclasts and osteoblasts. The resultant primary bone healing without creeping substitution within the dead bone is an alternative to conventional bone grafting in aiding or accelerating healing, replacing deficient bone, and/or revascularizing ischemic bone. Recent advances in understanding the anatomy and physiology of vascularized pedicled bone grafts have increased their use in treating a variety of carpal maladies. A basic understanding of the vascular anatomy, as well as the surgical principles and experimental and clinical results of pedicled vascularized bone grafts from the dorsal distal radius, is critical to understanding the use of these grafts in the treatment of scaphoid nonunions and Kienbock's disease.

Bone Transplantation↗