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H Fansa

Publications and source records attributed to H Fansa.

At least 37 records · Page 2Linked to original sources
PubMed2003

[Factors influencing nerve regeneration].

This paper describes the most important cellular and molecular factors that influence nerve regeneration. The first prerequisite for axonal regeneration is survival of the neuron. This depends on neuron type, age, and the degree and proximity of the injury to the cell body. Spinal motoneurons are less susceptible to injury-induced death than cranial motoneurons and sensory neurons. The surviving neurons undergo changes characteristic of a switch from a transmitting mode to a growing mode. They produce various neurotrophic factors and their receptors influencing the neuron and the non-neuronal cells such as Schwann cells. The distal nerve stump undergoes degenerative processes including removal of axons and phagocytosis of myelin debris, the so-called Wallerian degeneration. Until the second day phagocytosis is done by Schwann cells, hematogenous macrophages invade the distal stump at the second day and phagocyte the whole debris within two weeks. Devoid of axonal contact, the myelinating Schwann cells switch their function from myelination to growth support for the regenerating axons, including cell proliferation, downregulation of myelin components and upregulation of neurotrophic factors. Additionally, the Schwann cells form the so-called Bands of Büngner, cell columns serving as pathway for the growing axon. Trophic factors, cell adhesion molecules and extracellular matrix influence the neuron, the growing axon and the endorgan as well as the non-neuronal cells such as Schwann cells, fibroblasts and macrophages. Application of drugs or trophic substances to enhance nerve regeneration after trauma and reconstruction is in the very beginning, and thus requires further experimental and clinical studies. Experimentally, FK 506 was found to support axonal regeneration after crush lesions and nerve grafting. Growth factors are currently administered clinically in other neurological diseases.

Animals↗
PubMed2003

[Reconstruction of defects at the neuromuscular junction].

Loss of muscle tissue at the area of the neuromuscular junction after tumor resection or after trauma precludes the reconstruction with conventional nerve grafts, because the distal nerve stump is absent. For these cases, we recommend direct insertion of the nerve grafts into the muscle. We describe a standardized technique, which has been performed in 19 patients and led to a mean motor recovery of grade M4 after Highet. The key procedure of this technique is the interfascicular dissection of the nerve grafts, which allows a wide distribution of the grafts into the muscle tissue.

Adult↗
PubMed2003

Orthotopic and heterotopic lower leg reimplantation. Evaluation of seven patients.

Reimplantation is a well-established procedure in reconstructive surgery. This is especially so after amputation of the upper limb since prostheses provide limited function. In unilateral amputation of the lower leg orthotopic reimplantation is the treatment of choice. With bilateral amputation, in which orthotopic reimplantation is not possible because of the complexity of the trauma, heterotopic reimplantation is an option. We report five patients who received orthotopic and two who received heterotopic reimplantations of the lower leg. We assessed the functional outcomewith reference to cutaneous sensation, mobility, pain, and the cosmetic result. The functional outcome was good, as was the patients' satisfaction. Their mobility, stability, and psychological state were satisfactory. Patients with heterotopic reimplantations preferred the reimplanted leg to a prosthesis. Although reimplantation of the lower leg requires prolonged hospitalisation, delayed mobilisation and secondary operations, we conclude that there is an indication for this operation in order to improve the patient's quality of life.

Adolescent↗
PubMed2003

Nitric oxide synthase, an essential factor in peripheral nerve regeneration.

Nitric oxide (NO) exerts both, pro-apoptotic and anti-apoptotic actions and appears to be acritical factor inneuronal degenerative and regenerative processes. NO is synthesized from L-arginine by NO synthase occurring in three isoforms of (neuronal, nNOS; endothelial, eNOS; inducible, iNOS). In a mice sciatic nerve model the regenerative outcome was assessed when the endogenous NO supply was deficient by knocking out the respective NOS isoform and compared to that of wild type mice after nerve transection. In nNOS knock-out mice a delay in regeneration, preceded by slowedWallerian degeneration and a disturbed pruning of uncontrolled sprouts, was observed. This was associated with a delayed recovery of sensory and motor function. Additionally, deficiency of nNOS led after nerve cut to a substantial loss of small and medium-sized dorsal root ganglia neurons, spinal cord interneurons and, to a lesser extent, spinal cord motor neurons. A lack of iNOS resulted in a delayed Wallerian degeneration and impaired regenerative outcome without consequences for neuronal survival. A lack of eNOS was well tolerated, although a delay in nerve revascularization was observed. Thus, after peripheral nerve lesion, regular NOS activity is essential for cell survival and recovery with reference to the nNOS isoform.

Animals↗
PubMed2002

[Aggressive digital papillary adenocarcinoma - case report].

Digital papillary adenocarcinoma is a rare tumour originating from sweat glands, often occurring in digits of the hand or foot. We present the case of a 52-year-old mechanic with this tumour at the distal phalanx of the middle finger. It was primarily excised. After histological verification of the diagnosis, amputation and axillary lymphadenectomy was performed. So far, no clinical or histological parameters were found to be predictive for recurrence or metastasis. This indicates that the originally proposed criteria for distinguishing between benign (adenoma) and malignant (adenocarcinoma) do not necessarily predict biologic behaviour. As according to the available literature metastases occurred in 14 % of the described patients within ten years, we propose an aggressive surgical approach consisting of amputation and regional lymph node dissection.

Adenocarcinoma, Papillary↗
PubMed2002

[The influence on nerve regeneration by the beta2-receptor agonist clenbuterol].

PURPOSE: Clenbuterol has shown a neuroprotective action in the central nervous system by induction of growth factors after cellular damage. Additionally, the atrophy of sceletal muscle is attenuated by the application of Clenbuterol after denervation. This experiment was performed to show the influence of Clenbuterol on regeneration of peripheral nerves. MEHOD AND MATERIAL: In a rat model, the sciatic nerve was transected and microsurgically coaptated. Eight animals in each group received a daily oral dosage of 100 microg/kg bodyweight during four, respectively six weeks. Two control groups received only drinking water under the otherwise same protocol. The assessment was done histologically, morphometrically and clinically. The weight ratio of the soleus and extensor digitorum muscles of the operated to the contralateral side was measured. RESULTS: The groups treated with Clenbuterol showed histologically and morphometrically a significantly increased axon count and a better g-ratio. The muscle weight ratio was significantly higher in the Clenbuterol group after six weeks and more animals in this group were able to spread their toes. CONCLUSION: The oral application of Clenbuterol in a rodent model shows a positive influence on nerve regeneration.

Adrenergic beta-Agonists↗
PubMed2001

Regeneration of peripheral nerves after clenbuterol treatment in a rat model.

Clenbuterol is known to act as a neuroprotective substance in the central nervous system, and also reduces muscle atrophy after denervation. The aim of this study was to evaluate its influence on peripheral nerve regeneration. The rat sciatic nerve model was used in four groups (n = 8 per group). After complete nerve transection and microsurgical coaptation, two groups received a daily oral dose of 100 microg/kg clenbuterol and two served as controls. Regeneration was assessed clinically, histologically, and morphometrically after 4 and 6 weeks. The weight ratios of calf muscles were calculated. Histological examination showed significantly increased axon counts in the clenbuterol group and a better degree of myelination. Muscle weight ratios of the clenbuterol group were significantly increased after 6 weeks, and the animals showed improved function of the hindlimb. Thus, therapy with 100 microg/kg clenbuterol daily after coaptation of a sciatic nerve showed a positive influence on clinical, histological, and morphometrical parameters in the rat model. The underlying mechanism remains unclear.

Animals↗
PubMed2001

[Surgical treatment of axillary hidradenitis suppurativa].

INTRODUCTION: Hidradenitis suppurativa is a chronic inflammatory disease of the cutis with furuncles, fistulas and abscesses, mostly located in the groin and axillary regions. A conservative treatment can not prevent a recurrence. PATIENTS AND METHODS: We report on 16 patients with axillary hidradenitis suppurativa. The inflammatory region was excised, followed by immediate coverage with a transposition flap according to Limberg. Postoperatively, all patients received antibiotic treatment. After 2 weeks, physiotherapy was begun. RESULTS: All wounds healed primarily. Functional and aesthetic results were very satisfactory. Movement of the shoulder showed no restrictions. There was no major complication. The recurrence rate was low. DISCUSSION: Only radical debridement prevents a recurrence. The therapy of choice is radical excision of the affected region and immediate coverage by a transposition flap. Open granulation or split-skin grafting are inferior compared with a primary closure by transposition flap. Using the Limberg flap the donor site can be closed primarily.

Adult↗
PubMed2001

[Heterotopic replantation after bilateral lower leg amputation].

INTRODUCTION: Replantation is an established procedure in reconstructive surgery. In a bilateral lower leg amputation attempts should be made to rescue at least one extremity, if the patients' vital conditions are stable. PATIENT AND METHOD: We report on a patient who has suffered a bilateral lower leg amputation. Due to the complex injuries the left leg was heterotopically (cross-over) replanted to the right leg. At the left leg an above knee stump was created. In a second operation a soft tissue defect at the replanted extremity was covered by a free microvascular latissimus dorsi muscle flap. In addition, the tibial nerve was reconstructed. Thirteen months later the patient is able to walk with a prosthesis for his left leg and complete weight bearing of the replanted extremity. DISCUSSION: Indication for replantation depends on accompanying injuries and vital functions of the patient. Compared to a simple amputation a lower leg replantation prolongs hospital stay, delays mobilisation of the patient, and increases the necessary secondary procedures. However, after replantation functional outcome is mostly better than with prosthetic fitting, especially if reconstruction of sensation in the weight-bearing area is successful. Thus, in a bilateral amputation movement and stability, as well as quality of life, are improved by a replanted extremity.

Amputation Stumps↗
PubMed2001

[Therapy of chest wall osteomyelitis].

INTRODUCTION: Chronic osteomyelitis of the chest wall requires radical debridement and defect coverage with well-perfused tissue. The implantation of synthetic material is still under discussion because of the risk of infection. METHODS: A retrospective study was conducted on the complications and functional and aesthetic results of 26 patients with chest wall osteomyelitis after radiation or sternotomy treated by radical debridement and neurovascular pedicled latissimus dorsi muscle. RESULTS: The functional results were excellent with a low complication rate. The muscle showed electric activity synchronous with inspiration and clinically a stabilization of the thoracic defect. DISCUSSION: Maintained muscular activity may play an essential role for stabilizing thoracic defects of up to four ribs or the sternum; implantation of synthetic material is not necessary.

Adult↗
PubMed2001

[Surgical treatment of cicatricial carcinoma--methods and results].

INTRODUCTION: The prognosis of scar carcinoma, also known as Marjolin's ulcer, is poor. Metastases of lymph nodes often appear because of late diagnosis and the underestimation of clinical findings. This has a deep impact on the quality of life of the patients. Scar carcinoma often occurs in burn scars, but also in chronic ulcers of the lower extremities and in chronic pressure sores. METHODS: Between 1994 and 1998 12 patients with scar carcinoma were treated at our hospital. In all cases radical surgery of the entire scar area was undertaken, followed by dissection of the draining lymph nodes. Free flaps, pendicular flaps or splint skin grafts were used to cover the resulting defects. RESULTS: In 16.6% we observed positive lymph nodes. There were two cases of local recurrence. Five patients died during the observation time. In one patient the extremity had to be amputated. CONCLUSION: Early diagnosis and radical excision are requirements, and the quality of life can be improved with plastic surgery. Aftercare and yearly staging measures are mandatory.

Aged↗
PubMed2001

[Electrophysiological methods for diagnosis of entrapment syndromes of peripheral nerves].

Summary. Apart from clinical findings, the diagnosis of compression syndromes of peripheral nerves is based on electrophysiological investigations. This includes the determination of nerve conduction velocities, distal motor latency and electromyography, which gives a qualitative indication of the condition of nerves and their related muscles. In the 1980s, new methods were developed for quantifying the diagnoses of nerve lesions and their recovery. Due to the development of new software, we can now carry out these investigations with commercial equipment. The macro-EMG and the motor-unit-estimation give information about the size and number of activated motor units of muscles. One needs a special needle which derives single-fibre- and macro-potentials for recording of the macro-EMG. The single-fibre-potential is used for triggering. The motor-unit-estimation represents a non-invasive method to determine the approximate number of motor units. Multiple point stimulation of the nerve is used to determine action potentials which are registered by surface electrodes. Afterwards, the medians of amplitudes and areas of motor unit action potential are defined and must be divided by the corresponding value of maximal compound muscle action potential for estimating motor units. In this way, the extent of nerve damage can be determined exactly. Additionally, a post-operative follow-up is possible. Furthermore, these methods give information about regeneration processes after nerve damage and their recovery after reconstruction and transplantation. From our point of view, these methods should be included in investigation routinely.

Decompression, Surgical↗
PubMed2001

Revascularization of tissue-engineered nerve grafts and invasion of macrophages.

Nonneural derived nerve conduits fail to support regeneration over larger gaps due to lacking viable Schwann cells. Thus, tissue engineering of nerves is focusing on implantation of viable Schwann cells into suitable scaffolds. We established grafts made from acellular muscles and veins, respectively, seeded with cultured Schwann cells. As timing of revascularization is crucial to determine Schwann cell survival and depending axonal regeneration we studied establishment of vascular architecture in a rat sciatic nerve model (2-cm gap) after 3, 5, 7, and 10 days postoperatively, using albumin bound Evans blue. Additionally, macrophage recruitment was immunohistochemically assessed. Engineered grafts showed a delayed revascularization, starting between day 5 and 7 in comparison to normal autografts, that revascularized by day 3. Macrophage recruitment in autologous nerve grafts was evident by day 3. The engineered groups revealed no macrophage invasion until day 7. As Schwann cells survive up to 7 days in autologous grafts without blood supply, depending purely on diffusion, establishment of vascular structure between day 5 and 7 is rapid enough to support Schwann cell survival in engineered grafts. As these grafts are lacking Wallerian degeneration delayed macrophage invasion may not impair degeneration-dependent regeneration, but presence of macrophage derived or induced growth factors may be decreased.

Animals↗
PubMed2001

Tissue engineering of peripheral nerves: A comparison of venous and acellular muscle grafts with cultured Schwann cells.

Bioengineering is considered to be the laboratory-based alternative to human autografts and allografts. It ought to provide "custom-made organs" cultured from patient's material. Venous grafts and acellular muscle grafts support axonal regeneration only to a certain extent because of the lack of viable Schwann cells in the graft. We created a biologic nerve graft in the rat sciatic nerve model by implanting cultured Schwann cells into veins and acellular gracilis muscles, respectively. Autologous nerve grafts and veins and acellular muscle grafts without Schwann cells served as controls. After 6 and 12 weeks, regeneration was assessed clinically, histologically, and morphometrically. The polymerase chain reaction analvsis showed that the implanted Schwann cells remained within all the grafts. The best regeneration was seen in the control; after 12 weeks the number of axons was increased significantly compared with the other grafts. A good regeneration was noted in the muscle-Schwann cell group, whereas regeneration in both of the venous grafts and the muscle grafts without Schwann cells was impaired. The muscle-Schwann cell graft showed a systematic and organized regeneration including a proper orientation of regenerated fibers. The venous grafts with Schwann cells showed less fibrous tissue and disorganization than the veins without Schwann cells, but failed to show an excellent regeneration. This might be attributed to the lack of endoneural-tube-like components serving as scaffold for the sprouting axon. Although the conventional nerve graft remains the gold standard, the implantation of Schwann cells into an acellular muscle provides a biologic graft with basal lamina tubes as pathways for regenerating axons and the positive effects of Schwann cells producing neurotrophic and neurotropic factors, and thus, supporting axonal regeneration.

Animals↗
PubMed2000

Neuroma: a donor-age independent source of human Schwann cells for tissue engineered nerve grafts.

Schwann cells are used in combination with biological matrices as tissue engineered nerve grafts in animal models offering a new therapeutic approach for treatment of lesions of the peripheral nervous system. A high yield of human Schwann cells from adult donors is only achieved by pharmacological stimulation, which should, however, be avoided in clinical therapy. Here, we establish cultures of activated human Schwann cells which were isolated from peripheral nerve neuroma which developed after a median nerve lesion. To allow nerve reconstruction neuroma have to be resected. Such neuroma tissue is virtually predegenerated and shows activation of Schwann cells, implying good adherence and high mitotic activity. This allows, irrespective of donor age, growing within a short time period and without any pharmacological treatment.

Adult↗
PubMed2000

Cryopreservation of peripheral nerve grafts.

The utilization of viable biological nerve graft substitutes and nerve allografts raises the problem of nerve storage. To clarify this, rat sciatic nerve segments were harvested and stored in Dulbecco's modified eagle medium. The segments were divided into three groups. In the first group, no cryoprotectant was added, whereas the second had 10% dimethyl sulfoxide (DMSO) added as cryoprotectant. These two groups of nerve segments were subjected to controlled freezing. In a third group, segments were frozen uncontrolled in liquid nitrogen (-196 degrees C). All nerves were replanted orthotopically. Fresh conventional autografts (fourth group) served as control group. Histologically, freezing did not affect the structural elements such as basal lamina tubes and perineurial tissue. Morphometrically, all cryopreserved grafts had significantly reduced axon counts and less myelinization than did controls. Cryoprotected nerves (group 2) showed no different morphometric parameters compared with the group without DMSO (group 1). Controlled freezing was superior to uncontrolled freezing (group 3). Impaired regeneration was attributed mainly to delayed Wallerian degeneration and slower revascularization. Moreover, decreased survival of resident Schwann cells in the graft may impair regeneration due to the lack of neurotrophic, neurotropic, and attachment factors in early regeneration. Grafts subjected to controlled freezing support axonal regeneration to a certain extent, but further studies are required to assess various cooling patterns, cryoprotectants, and graft revascularization.

Animals↗