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Biomedical subjects

N F Jones

Publications and source records attributed to N F Jones.

At least 37 records · Page 2Linked to original sources
PubMed1999

Ulcerated plaque in the ulnar artery causing distal seeding of microemboli: a possible early stage of ulnar artery thrombosis.

Angiography of a patient presenting with ischemia of the ring and small fingers, but with patent arterial inflow through the ulnar artery on Allen's test, demonstrated stenosis of the ulnar artery just distal to Guyon's canal. Surgical exploration revealed a discrete ulcerated plaque with an overlying loosely adherent thrombus. An ulcerated plaque in one of the main inflow arteries to the hand may produce ischemia of the fingers by seeding microemboli distally into the digital arteries. This pathophysiologic mechanism may represent a very early phase of incipient or impending thrombosis of the ulnar artery and may eventually progress to complete thrombosis. Early recognition and treatment by resection of the involved arterial segment and microsurgical reconstruction may prevent the evolution to complete ulnar artery thrombosis.

Aged↗
PubMed1998

New concepts and materials in microvascular grafting: prosthetic graft endothelial cell seeding and gene therapy.

Microsurgical free tissue transfer is currently associated with very high success rates and few complications. While interposition vein grafting is clearly an important adjunct to the microsurgeon's armamentarium, it has been associated with higher free flap/replantation failures and complication rates. With appropriate flap planning and surgical techniques, the need for interposition vein grafting should be quite infrequent and hopefully avoided if at all possible. Nevertheless, when necessary, the vein graft remains the gold standard, with virtually all alternative interposition grafts demonstrating lower patency rates. One of the more promising areas of research is the concept of genetic manipulation of the endothelial cell via molecular biological techniques. It is likely that in the near future this may become a clinical reality, not only improving the patency of microsurgical anastomoses and interposition vein grafts, but quite possibly altering the target organ functionally as well.

Animals↗
PubMed1998

Limb xenotransplantation using FK506 and RS61443 immunosuppression.

A new model of limb xenotransplantation has been developed to determine whether the newer immunosuppressive agents, FK-506 and RS-61443, either alone or in combination, can delay the rejection of a composite limb xenograft from donor Golden Syrian hamsters to recipient Lewis rats. Using a short-term course of immunosuppression for 14 days post-transplant, both FK-506 2 mg/kg/day and RS-61443 30 mg/kg/day were able to delay rejection. FK-506-treated animals had a mean rejection time of 10.2 days and RS-61443-treated animals had a mean rejection time of 10 days, compared with a mean rejection time of 6.4 days in non-immunosuppressed controls. Combination and sequential immunosuppression with both FK-506 and RS-61443 did not produce any improvement, compared with single-agent immunosuppression, and were quite toxic. Histologically, FK-506 seemed to prevent signs of rejection in the skin and muscle components of the limb xenograft better than RS-61443.

Animals↗
PubMed1998

Use of the Taguchi method for biomechanical comparison of flexor-tendon-repair techniques to allow immediate active flexion. A new method of analysis and optimization of technique to improve the quality of the repair.

The current trend toward early active flexion after repair of the flexor tendons necessitates a stronger repair than that provided by a modified Kessler technique with use of 4-0 nylon suture. The purpose of the current study was to determine, with use of the Taguchi method of analysis, the strongest and most consistent repair of the flexor tendons. Flexor tendons were obtained from fresh-frozen hands of human cadavera. Eight flexor tendons initially were repaired with the modified Kessler technique with use of 4-0 nylon core suture and 6-0 nylon epitenon suture. A test matrix was used to analyze a total of twenty variables in sixty-four tests. These variables included eight techniques for core-suture repair, four types of core suture, two sizes of core suture, four techniques for suture of the epitenon, and two distances from the repair site for placement of the core suture. After each repair, the specimens were mounted in a servohydraulic mechanical testing machine for tension-testing to failure. The optimum combination of variables was determined, with the Taguchi method, to be an augmented Becker technique with use of 3-0 Mersilene core suture, placed 0.75 centimeter from the cut edge with volar epitenon suture. The four-strand, double modified Kessler technique provided the second strongest repair. Five tendons that had been repaired with use of the optimum combination then were tested and compared with tendons that had been repaired with the standard modified Kessler technique. With the optimum combination of variables, the strength of the repair improved from a mean (and standard deviation) of 17.2 +/- 2.9 to 128 +/- 5.6 newtons, and the stiffness improved from a mean of 4.6 to 16.2 newtons per millimeter.

Biomechanical Phenomena↗
PubMed1998

[Genetic methods in experimental xenogenic nerve transplantation].

The ready availability of xenografts and the promising results of genetic engineering both may offer new methods in peripheral xenotransplantation. FK506 and RS61443 are able to prolong survival of nerve xenografts. The incorporation of adenoviral sequences in xenogeneic tissues is possibly a new option for decreasing the toxicity of immunosuppressive drugs and immunogenicity of grafts.

Animals↗
PubMed1997

Nerve xenograft transplantation. Immunosuppression with FK-506 and RS-61443.

An experimental model has been developed to study the potential transplantation of nerve xenografts using the newer immunosuppressive agents RS-61443 and FK-506. Sciatic nerve grafts of 2 cm were transplanted from donor Golden Syrian hamsters into a 0.5 cm gap in the sciatic nerve of recipient Lewis rats. Walking track analysis, somatosensory evoked potentials and histology demonstrated improved regeneration across the nerve xenografts that had been immunosuppressed with RS-61443 and FK-506 compared with non-immunosuppressed controls, but the function never approached that seen in control isografts. Regeneration across nerve xenografts immunosuppressed with FK-506 was better than xenografts immunosuppressed with RS-61443.

Animals↗
PubMed1997

Circumferential wrapping of a flap around a scarred peripheral nerve for salvage of end-stage traction neuritis.

Nine patients with chronic severe pain due to end-stage traction neuritis of an intact peripheral nerve underwent external neurolysis and epineurectomy or epineurectomy and internal neurolysis followed by circumferential wrapping of the involved segment of nerve with a pedicle flap or free flap consisting of either subcutaneous fat tissue, fascia, or muscle. Seven patients (77%) followed for between 1 and 5 years had substantial relief of pain. Two patients (22%) had no decrease in their pain at all. Circumferential wrapping may cushion the nerve from external pressure on the overlying skin, may isolate the nerve from the traction forces of adjacent moving tendons to allow improved gliding of the nerve, and may promote revascularization of a scarred nerve. This surgery may be indicated for patients with persistent pain following multiple carpal tunnel or cubital tunnel surgeries.

Adult↗
PubMed1997

The use of surgical sympathectomy in the treatment of chronic renal pain.

OBJECTIVE: To assess the efficacy of renal sympathetic denervation in the treatment of chronic renal pain. PATIENTS AND METHODS: In a 10-year period, 21 patients suffering from chronic renal pain underwent 27 renal denervation operations, six of which were bilateral. The cause of pain was the loin pain haematuria syndrome in 18 patients. RESULTS: Four operations resulted in complete pain relief to date (median follow-up 53.5 months). Pain relief after the other 23 operations in 18 patients lasted a median of 6 months. Assuming that recurrent pain was due to neuronal regeneration, nine of the 18 patients with recurrent pain underwent a total of 10 re-explorations of the renal pedicle, stripping it of all nerve fibres and areolar tissue. Three of these re-explorations produced complete pain relief to date (median follow-up 40 months). The median pain-free interval of the other seven re-explorations in six patients was 19 months. CONCLUSION: Renal denervation cures severe intractable pain in about 25% of patients. Recurrence of pain could be prevented in more patients if there was a way of preventing re-innervation.

Adult↗
PubMed1997

Gene transfer into nerve and muscle by isolated limb perfusion or during replantation.

In this study, the authors tested the feasibility of adenovirus vectors transferring functional genetic material into relevent soft-tissue structures during replantation of mouse hindlimbs. An adenovirus vector was constructed encoding the marker gene LacZ and CMV promoter and titered by plaque forming assay to 5 x 10(9) particles/ml. C3H mouse hindlimbs were divided into three groups. In Group 1 (n = 9), the femoral neurovascular bundle was divided and re-anastomosed . Group 2 (n = 9) hindlimbs were transected at mid-femur, perfused with adenovirus, and replanted. Group 3 limbs (n = 4) were perfused with saline only, followed by replantation. After 48 hr, morbidity and mortality were assessed, and the replanted limbs were assayed for gene transfer by histochemistry and polymerase chain reaction. 12/18 limbs were viable after 48 hr. Histochemical staining for adenovirus-mediated LacZ expression was positive within skeletal muscle, femoral nerve, and capillaries adjacent to the anastomoses. Distal muscle was also gene transfer positive. PCR analysis confirmed adenovirus-mediated gene transfer within the femoral nerve and skeletal muscle. This study confirms that viral-mediated gene transfer can be accomplished into the soft tissues of a replanted extremity.

Adenoviridae↗
PubMed1997

Reconstructed mandibular defects: fibula free flaps and osseointegrated implants.

Twenty patients with microvascular fibula flap reconstruction of oromandibular defects were selected for implant-retained prosthodontic rehabilitation. A total of 71 osseointegrated implants were placed within the grafted fibulas. Four patients had immediate implant placement at the time of their reconstructive surgery, and the remaining 16 patients had implants placed secondarily. One patient received postoperative radiation therapy (5910 cGy) 6 weeks following reconstruction and immediate implant placement. No implants were placed in previously irradiated flaps. A minimum 6-month period of osseointegration was allowed prior to second stage surgery. Fifty-four of the 71 implants were uncovered; 46 of these implants were functional, and 3 were in the process of being restored. Among the 54 implants (15 patients) that were uncovered, only 1 failed to osseointegrate, 2 implants were reburied, and 2 were removed. The follow-up period ranged from 1 to 49 months since second stage surgery. Although a number of prosthodontic designs were used, 11 of the 15 patients were restored with removable overlay prostheses. Only those implants exposed to postoperative radiation demonstrated radiographic bone loss following functional loading.

Adult↗
PubMed1996

Compression neuropathy of the palmar cutaneous branch of the median nerve by the antebrachial fascia.

An isolated compression neuropathy of the palmar cutaneous branch of the median nerve is described in a woman who presented with a small tender mass over the anterior aspect of her distal forearm and complete numbness over the thenar eminence. Surgical exploration revealed thickening of the palmar cutaneous nerve as it passed upwards through the antebrachial fascia on the ulnar aspect of the flexor carpi radialis tendon. Neurolysis of two separate fascicles of the palmar cutaneous branch of the median nerve and excision of a window of antebrachial fascia resulted in complete return of sensation over the thenar eminence.

Adult↗
PubMed1996

Microsurgical reconstruction of the head and neck: interdisciplinary collaboration between head and neck surgeons and plastic surgeons in 305 cases.

Three hundred five microsurgical free flaps have been performed for defects of the head and neck by a team of two head and neck surgeons and two plastic surgeons over a 9-year period, with a success rate of 91.2%. The most common flaps used were the jejunum (89), radial forearm (57), rectus abdominis (48), latissimus dorsi (40), scapular (32), fibula (15), and iliac crest (11). Thirty-three flaps required reexploration for anastomotic thrombosis or hematoma (10.8%), of which 18 flaps were salvaged (54.5%). Thirteen flap failures occurred in 113 patients who had received preoperative irradiation (11.5%), but this was not statistically significant. Seven flaps failed in 20 patients who required an interposition vein graft (35%) and this was statistically significant. Ninety patients (31.5%) developed a major complication other than anastomotic thrombosis or death. Despite postoperative intensive care nursing and monitoring, 18 patients died postoperatively in the hospital (6.3%). The average hospital stay was 21.1 days with a range from 5 to 95 days. During this 9-year time period, various free flaps have evolved as the preferred choice for free flap reconstruction of a specific defect of the head and neck. The latissimus dorsal muscle flap surfaced with a nonmeshed split-thickness skin graft is the optimal free flap for reconstruction of the scalp and skull, whereas a multiple-paddle latissimus dorsi musculocutaneous flap is the best flap for reconstruction of complex defects of the middle third of the face and maxilla. The radial forearm flap and free jejunal transfer have become the preferred choices for intraoral reconstruction and pharyngo-esophageal reconstruction, respectively. There still remains no universally accepted flap for mandibular reconstruction, but the fibular osteocutaneous flap and a reconstruction plate protected by a radial forearm flap have largely superseded the iliac crest and scapular osteocutaneous flaps. Radical resection of tumors of the head and neck with immediate reconstruction by microsurgical free tissue transfer followed by adjuvant radiation therapy provides the best possible chance for cure and functional and social rehabilitation of the patient.

Adolescent↗
PubMed1996

Rejection of the component tissues of limb allografts in rats immunosuppressed with FK-506 and cyclosporine.

One-hundred and fourteen limb transplantations have been performed across a major histoincompatibility barrier between donor ACI (RT1a) and recipient Lewis (RT1l) rats immunosuppressed with various dosages of FK-506 and cyclosporine. Three-hundred and thirty biopsy specimens from 64 animals have been evaluated histologically for signs of rejection. A new histologic grading system is introduced to classify the process of rejection in the component tissues (skin, muscle, bone, and articular cartilage) of a limb allograft. The results indicate that FK-506 is a more potent immunosuppressive agent than cyclosporine in preventing the rejection of the skin component of a limb transplant. With twice-weekly intermittent immunosuppression with FK-506, the rejection of muscle, bone, and cartilage can be prevented for an indefinite time, although all long-term surviving animals died at around 300 days, probably of graft-versus-host disease. Based on the histologic stages of rejection in the different tissues at the same point in time, it is evident that each component tissue of a limb transplant rejects over a different time period. This probably reflects a hierarchy of antigenicity, with skin being most antigenic, muscle being intermediate in antigenicity, and bone and cartilage being least antigenic. Although this grading system is not the ultimate solution, it may allow a more objective comparison of experimental limb transplantation in the future.

Analysis of Variance↗
PubMed1996

Reliability of the fibular osteocutaneous flap for mandibular reconstruction: anatomical and surgical confirmation.

There is ongoing controversy regarding the reliability of the skin island associated with the fibular osteocutaneous flap for mandibular reconstruction. Anatomical dissections and a clinical series of mandibular reconstructions using the fibular osteocutaneous flap have demonstrated unequivocally that a skin flap can be reliably harvested with the fibula based purely on the septal perforators, without needing to incorporate portions of the soleus or flexor hallucis longus muscles or to perform any intramuscular dissection or anastomosis of the muscle perforators. However, the skin island should be designed more distally over the distal third of the lower leg at the junction of the middle and distal thirds of the fibula. A fibular osteocutaneous flap was designed over the distal third of the fibula in 60 fresh cadavers, and each flap was completely isolated on the septum and all muscle perforators were ligated before dye injection. A major perforator through the soleus muscle or flexor hallucis muscle was identified in 41 of 60 dissections (67 percent) and discrete septal perforators were identified under loupe magnification in 45 dissections (75 percent). All 60 flaps demonstrated 100 percent reliable perfusion of the skin island after injection of the proximal peroneal artery with methylene blue or red latex. This anatomical study was corroborated with 100 percent survival of 34 fibular osteocutaneous flaps for mandibular reconstruction with the skin island designed over the distal third of the lower leg and based only on septal perforators without incorporating the soleus or flexor hallucis muscles. Reliability of this fibular osteocutaneous flap for mandibular reconstruction is attributed to (1) design of the skin island more distally over the distal third of the lower leg, (2) preoperative precision Doppler mapping of the perforators, and (3) design of the closing wedge osteotomies of the fibula to protect the septocutaneous perforators transversing through the posterior periosteum of the fibula.

Cadaver↗