Biomedical subjects

M Voigt

Publications and source records attributed to M Voigt.

At least 37 records · Page 2Linked to original sources

PubMed2001

Management of hypovascularized wounds not responding to conventional therapy by means of free muscle transplantation.

BACKGROUND: Chronic ulceration as a complication of arteriosclerotic disease, venous congestion or diabetes mellitus is still a serious clinical problem, resulting in immobilization, extended hospitalization and cost-intensive treatment. Other than standard conservative treatment protocols or early amputation, microsurgical free transfer of well vascularized muscle tissue onto chronic wounds can induce angiogenesis and improve wound healing even in the hypovascularized wound. PATIENTS: From 1993-1999 we treated 12 patients (mean age: 46 years) with vascular ulcers of the lower extremity with free muscle or fasciocutaneous tissue transfer. RESULTS: The average hospitalization was 51.4 days. The perioperative mortality was zero. In one patient with factor V deficiency a partial flap necrosis occurred. Two revisions of the micro anastomoses had to be performed. Two seromas occurred at the donor site. No secondary flap loss was observed. Extremity or stump length preservation was achieved in all cases. CONCLUSIONS: Optimal postoperative treatment with physiotherapy and orthopaedic shoe support is important. If all these factors are present and if the patient is highly motivated a reintegration into normal life can be achieved.

Adult↗

PubMed2001

[Reconstruction of abdominal-wall midline defects--The Abdominal-Wall Components Separation].

AIM OF THE STUDY: The recurrence rate of midline defects like incisional hernias is high. Alloplastic material in sublay or onlay technique is often be used if the suture tension is to high for a primary closure. Free or pedicled musculocutaneous flaps transfer denervated muscle and lack dynamic resistance against the intraabdominal pressure. The separation of the lateral abdominal wall achieves autogenous, dynamic material for a tension free closure in small and moderate midline defects. METHODS: In 1990 Ramirez described a technique, which separates parts of the lateral abdominal wall and advances it towards the midline. The innervation and blood supply of the advanced part is maintained. With this technique it is possible to close defects tension free with dynamic abdominal wall. 9 patients were treated with this technique and followed up. RESULTS: Midline defects up to 16 cm at the waistline could be closed without tension. There were no major complications (one small delayed wound healing). There were no recurrences in a follow up time of 14.2 months. CONCLUSION: The separation of parts of the lateral abdominal wall can achieve tension free closure of e.g. incisional hernias of small and moderate size. The advancement of the medial component provides well innervated muscle for dynamic resistance against the abdominal pressure.

Adult↗

PubMed2001

Plasmid gene delivery to human keratinocytes through a fibrin-mediated transfection system.

We have developed a matrix-mediated transfection system to deliver plasmids to human keratinocytes. The matrix is a soluble, self-hardening fibrin matrix (Tissucol), Baxter) that has been used clinically. Recently it has been shown that full thickness burn wounds can be successfully treated with a keratinocyte fibrin glue suspension. Further, it has been demonstrated that hEGF transfected cells accelerate wound healing. In this study, we inoculated the matrix with the hEGF expression plasmid and resuspended the matrix with either cultured or noncultured human keratinocytes. We obtained successful transfection rates of these cells (up to a 100-fold increase compared to controls containing no EGF expression plasmid) in vitro. After transplantation to full thickness wounds on athymic mice we were able to show a 180-fold increase in EGF concentration compared to controls, which persisted over the entire 7-day monitored period, decreasing from 180 to 20 pg/mL at day seven. This unique approach indicates the possible utility to combine a matrix for cell transplantation with a transfection system to release therapeutic proteins in vitro and in vivo.

Animals↗

PubMed2001

Slow release of acetylsalicylic acid by intravitreal silicone oil.

PURPOSE: To assess in vitro the potential of silicone oil as a delivery system for acetylsalicylic acid (ASA) and to evaluate in vivo the pharmacokinetic distribution of salicylic acid (SA) in the eye. METHODS: In an experimental model ASA/silicone oil suspension mixed to a concentration of 1.67 mg/mL was investigated for release rate of ASA and SA. In vivo vitrectomy and intravitreal injection of two different ASA/silicone oil suspensions, both mixed to a concentration of 1.67 mg/mL, was performed on two groups, A and B, of New Zealand white rabbits. Salicylic acid concentrations in ocular tissues, aqueous, vitreous, and blood plasma were evaluated at 6 hours, 24 hours, and 5 days using high performance liquid chromatography. RESULTS: Salicylic acid was detected in all tissues. The highest levels were obtained in the vitreous: 745.4 microg/mL (A) and 640.0 microg/mL (B) at 6 hours. The retina followed with 332.9 ng/mg (A) and 281.3 ng/mg (B) at 6 hours and 31.6 ng/mg (A) and 48.1 ng/mg (B) at day 5. The maximum blood plasma levels were 5.2 microg/mL. CONCLUSION: Silicone oil is an efficacious delivery system of ASA in vitro and in vivo. Higher concentrations of SA were found in all ocular tissues and fluids when compared to intravenous administration of maximum doses.

Animals↗

PubMed2001

Consecutive occurrence of primary biliary cirrhosis and autoimmune hepatitis: a case report and review of the literature.

Autoimmune cholangiopathy is a term that describes a subset of patients with overlapping features of primary biliary cirrhosis (PBC) and autoimmune hepatitis (AH). These patients typically have cholestasis, negative antimitochondrial antibody (AMA), liver histology suggestive of PBC, and may respond clinically to corticosteroid therapy. We describe a patient who presented with typical AMA-positive, biopsy-proven PBC who responded to ursodeoxycholic acid therapy both clinically and biochemically. Approximately 3 yr later, she developed elevated transaminases with biopsy-proven antinuclear antibody (ANA) negative AH. The AMA was negative at this time. After responding to steroid therapy for the AH and after discontinuing the ursodeoxycholic acid, the patient had a clinical recurrence of PBC with renewed AMA positivity.

Female↗

PubMed2001

The change from general nurse education to a nursing diploma in Papua New Guinea.

Papua New Guinea has started to change from a hospital based general nurse training to a competency based, university linked, diploma of nursing training program. This paper looks at the development of nurse education in Papua New Guinea. It also briefly outlines the present and proposed courses. The expected benefits and anticipated problems are then discussed and the paper ends with challenges being faced by those involved in nurse education.

Education, Nursing, Diploma Programs↗

PubMed2001

International union of pharmacology. XXIV. Current status of the nomenclature and properties of P2X receptors and their subunits.

ATP acts as a humoral mediator to control cell function extracellularly. The receptors that mediate the actions of ATP belong to two classes, the metabotropic P2Y receptors and the transmitter-gated, ion channel P2X receptors. This review describes the structure, distribution, function, and ligand recognition characteristics of P2X receptors, which comprise seven distinct subunits that can function as both homo- and hetero- polymers. The pharmacology of P2X receptors is complicated by marked differences between species orthologues. The current nomenclature is based largely on recombinant receptor studies and detailed knowledge of endogenous P2X receptors in native tissues is limited because of lack of good selective agonists and antagonists for each receptor type.

Animals↗

PubMed2001

Renal function, sodium and water homeostasis in patients with idiopathic extrahepatic portal vein thrombosis compared with normal healthy controls.

OBJECTIVES: To determine whether portal hypertension in the absence of liver disease contributes to changes in renal function and renal sodium and water handling. METHODS: Nine patients with extrahepatic portal vein thrombosis (PVT) with normal liver function and histology were compared with 9 matched healthy control subjects. All underwent standard measurements of glomerular filtration rate and effective renal blood flow using inulin and paraaminohippuric acid (PAH) clearances, respectively. Sodium excretion and renin and aldosterone levels were studied before, during and after an intravenous saline infusion. RESULTS: At baseline there were no differences in inulin clearance, PAH clearance, fractional excretion of sodium and free water excretion. During and after the saline infusion both groups showed a significant increase in sodium excretion with a reduction in water excretion, while the PAH and inulin clearances remained unchanged. Although aldosterone and renin levels both fell after the infusion, aldosterone levels were significantly lower in the PVT group. There were no other significant differences between the PVT and control groups. CONCLUSION: Renal function and sodium and water handling were comparable in healthy controls and patients with PVT. It is unlikely that portal hypertension alone plays a significant role in the impaired ability to excrete sodium and water in patients with liver cirrhosis.

Adult↗

PubMed2001

A look behind the screens in Papua New Guinea.

Nursing care is affected by the culture we live in and even when nursing care is given the same way in different societies, it can be given that way for different reasons. This was found when doing a comparison between how certain aspects of nursing care were performed and viewed in Australia and Papua New Guinea. The framework for comparison was derived from part of Lawler's book (1991) Behind the Screens: Nursing, Somology, and the Problem of the Body. The feelings and accounts of staff and students working in Papua New Guinea (in 1997) are compared with those expressed by Australian nurses interviewed by Lawler in the mid 1980s. Interviews and observations in Papua New Guinea are summarised and then analysed looking at similarities and differences between the two cultures especially in giving body care and care after death.

Australia↗

PubMed2000

Design of a magnetically integrated microporous implant.

OBJECTIVE: To determine the orbital tolerance of a microporous implant fitted with an integrated stainless steel post and the enhanced motility associated with magnetic coupling of the prosthetic and the implant in a rabbit model. METHODS: Six New Zealand white rabbits underwent primary enucleation with implantation of a 12-mm microporous polyethylene implant with a 2 x 3-mm stainless steel post embedded flush with the anterior surface. At 1 month, the rabbits were fitted with an external prosthesis containing two 1-mm circular rare earth dental magnets embedded at 0. 5 mm off the midline (right and left of center at the horizon). Magnetic coupling forces were determined with a hanging block technique. RESULTS: No evidence of toxicity was observed in association with this integrated ocular implant. Magnetic coupling forces were noted maximally at 0.47 N. Clinical grading of motility documented enhancement in lateral excursion when compared with nonintegrated controls. CONCLUSION: Magnetically integrated microporous implants achieve excellent enhancement of motility without evidence of complications in this rabbit model. CLINICAL RELEVANCE: This study establishes a framework for the clinical evaluation of a magnetically integrated implant that may enhance prosthetic motility without requiring direct mechanical coupling of the implant to the prosthesis. Arch Ophthalmol. 2000;118:1259-1262

Animals↗

PubMed2000

Kinetics and energetics during uphill and downhill carrying of different weights.

During physically heavy work tasks the musculoskeletal tissues are exposed to both mechanical and metabolic loading. The aim of the present study was to test a biomechanical model for prediction of whole-body energy turnover from kinematic and anthropometric data during load carrying. Total loads of 0, 10 and 20 kg were carried symmetrically or asymmetrically in the hands, while walking on a treadmill (4.5 km h(-1)) horizontally, uphill, or downhill the slopes being 8%. Mean values for the directly measured oxygen uptake ranged for all trials from 0.5 to 2.1 l O2 min(-1), and analysis of variance showed significant differences regarding slope, load carried, and symmetry. The calculated values of oxygen uptake based on the biomechanical model correlated significantly with the directly measured values, fitting to the line Y = 0.990 X + 0.144, where Y is the estimated and X is the measured oxygen uptake in l min(-1). The close relationship between energy turnover rate measured directly and estimated based on a biomechanical model justifies the assessment of the metabolic load from kinematic data.

Adult↗

PubMed2000

Kinematic and kinetic analysis of the walking pattern in hemiplegic patients with foot-drop using a peroneal nerve stimulator.

OBJECTIVE: To analyze the walking pattern in hemiplegic patients using a peroneal nerve stimulator to locate possible harmful mechanical effects on the musculo-skeletal system. DESIGN: Eight hemiplegic patients participated in the study. All patients had used a peroneal nerve stimulator regularly for more than two years and were able to perform unassisted walking. BACKGROUND: Peroneal nerve stimulators are widely applied for correction of foot-drop in hemiplegic patients. The stimulators do not induce normal dorsi-flexion, but a rather exaggerated dorsi-flexion and eventually eversion which might be harmful. METHODS: Three-dimensional kinematic and kinetic analyses of the walking patterns at self-selected speeds were performed with the patients walking without the stimulator and with the stimulator turned on. RESULTS: The walking speed increased on average from 0.77 (S.D., 0.83) to 0.84 (S.D., 0.11) (7.6%, P=0. 005) when the stimulator was used, however no uniform changes in the walking pattern and joint loads were observed. The total work (generation+absorption) produced by the affected leg (both with and without the peroneal nerve stimulator) was significantly lower (P=0. 005) than that of the contralateral leg. Deviations from normal power profiles were observed both on the affected and the contralateral side, and the walking efficiency was 57% lower compared to normal subjects. The estimated peak bone-on-bone forces corresponded to about 50% of what previously has been observed during normal walking at self-selected speed. CONCLUSIONS: The use of the peroneal nerve stimulator do not introduce any excessive and potential harmful mechanical loads. RELEVANCE: Applied correctly, the peroneal nerve stimulator can be used as an aid for foot-drop correction in hemiplegic patients without causing excessive wear on the joints in the lower extremity.

Analysis of Variance↗

PubMed2000

Dynamic viscoelastic behavior of lower extremity tendons during simulated running.

The aim of this project was to see whether the tendon would show creep during long-term dynamic loading (here referred to as dynamic creep). Pig tendons were loaded by a material-testing machine with a human Achilles tendon force profile (1.37 Hz, 3% strain, 1,600 cycles), which was obtained in an earlier in vivo experiment during running. All the pig tendons showed some dynamic creep during cyclic loading (between 0.23 +/- 0.15 and 0.42 +/- 0.21%, means +/- SD). The pig tendon data were used as an input of a model to predict dynamic creep in the human Achilles tendon during running of a marathon and to evaluate whether there might consequently be an influence on group Ia afferent-mediated length and velocity feedback from muscle spindles. The predicted dynamic creep in the Achilles tendon was considered to be too small to have a significant influence on the length and velocity feedback from soleus during running. In spite of the characteristic nonlinear viscoelastic behavior of tendons, our results demonstrate that these properties have a minor effect on the ability of tendons to act as predictable, stable, and elastic force transmitters during long-term cyclic loading.

Achilles Tendon↗

PubMed2000

[Tissue engineering: possibilities and perspectives].

Successful tissue engineering requires intensive co-oporation between clinicians, biologists (cell culture, gene therapy), chemical engineers (biomaterials) and industrial partners. In case of wound healing tissue engineered constructs have already been applied successfully in burns and chronic wounds. In order to improve carrier and matrix function biomaterials still have to be optimized. The potential of such constructs might even be enhanced by gene therapeutical methods. The complex mammalian organism has to be considered as the gold standard and the model for perfect tissue engineering. The problem of vascularization of complex organs yet has to be solved. In general it seems to be more promising to substitute deficient components in vivo and to rely on modulating influences within the host organism rather than to create complex organs ex vivo.

Animals↗

PubMed2000

[Gene therapy perspectives in modulation of wound healing].

A variety of reasons can afflict wound healing. Current research is focussed on the acceleration of wound healing by stimulating molecular processes. Gene therapy may offer completely new ways to treat chronic wounds. Possible advantages of gene therapeutic modulation of wound healing might be a long term efficiency, systemic or local regulation of gene expression and low side-effects. Current goals comprise the improvement of transfection efficiency and specificity. In vivo applications are therefore focussed on optimized inducible or even cell-type specific promotors, as well as on improved local application techniques. Studies from our laboratory demonstrate the possibility to combine modern cell culture techniques with different types of gene transfer. This enables the simultaneous grafting of manipulated cells to the wound with the continuous delivery of specific proteins of interest. Experimentally, this lead to accelerated closure of partial and full thickness animal wounds. Clinically, gene therapy for the treatment of chronic wounds seems to be a realistic goal within the next years and might be applicable for a variety of novel indications.

Animals↗

PubMed1999

Shoulder muscle co-ordination during chronic and acute experimental neck-shoulder pain. An occupational pain study.

Little is known about the mechanisms leading to chronic neck-shoulder musculoskeletal disorders (MSD). The aim of the present study was to investigate and compare motor function during controlled, low load, repetitive work together with chronic or acute experimental neck-shoulder pain. The clinical study was performed on workers with (n = 12) and without (n = 6) chronic neck-shoulder pain. In the experimental study, experimental muscle pain was induced in healthy subjects by intra-muscular injection of hypertonic saline into the trapezius muscle (n = 10). The assessed parameters related to motor performance were: work task event duration, cutting forces, surface electromyogram (EMG) activity in four shoulder muscles, displacement of the centre of pressure, and arm and trunk 3D movements. For controlled cutting force levels, chronic and acute experimental pain provoked a series of changes: a decreased working rhythm and a protective reorganisation of muscle synergy (experimental study), higher EMG frequency contents which may indicate altered motor unit recruitment, and greater postural activity and a tendency towards increased arm and trunk movements. These pain-related changes can play a role in the development of MSD. The present clinical and experimental study demonstrated similar interactions between motor co-ordination and neck-shoulder pain in occupational settings. We therefore suggest that this experimental model can be used to study mechanisms related to MSD. Information on such modulatory processes may help in the design of new strategies aimed at reducing the development of MSD.

Acute Disease↗

PubMed1999

Reorganisation of human step initiation during acute experimental muscle pain.

The effects of experimentally induced pain in tibialis anterior on step initiation were studied in six healthy male volunteers by kinematics, kinetics and electromyography (EMG). We observed longer reaction times, lower joint moments and decreased EMG activity in the painful leading leg's tibialis anterior and gastrocnemius muscles. Peripheral nociceptive input appeared to alter the internal representation used in the step initiation motor program.

Adult↗

PubMed1999

Cultured epidermal keratinocytes on a microspherical transport system are feasible to reconstitute the epidermis in full-thickness wounds.

Research efforts to modify cultured autologous skin transplants for large full-thickness burn wounds and in chronic ulcers have shifted from multilayered differentiated grafts ("sheet" grafts) toward smaller units of basal undifferentiated single cell suspensions in a transport medium and subconfluently covered static carriers. It has been shown that wounds transplanted with single cell suspensions reconstitute the epidermis. However, this technique requires the detachment of the keratinocytes from the culture flasks by enzymatic digestion-digestion that might alter the anchoring proteins of the cells. A new approach might be to circumvent the enzymatic digestion to harvest the keratinocytes. This study reports a technique to culture epidermal cells on spherical microcarriers as a suspension culture and transport vehicle. The spherical microcarrier consists of a 100-microm-diameter collagen-coated dextran carrier (Cytodex 3 Pharmacia) and has been used previously for enzyme production commercially. With this new approach, we seeded the human keratinocytes in a spinner-like system onto microspheres and transplanted these micrografts onto full-thickness wounds on the back of nude mice. After 14 days, we showed a reconstituted epithelium that was multilayered and keratinized compared to control wounds. We believe that this is the first step of a new approach to increase the cell yield for seeding without altering the anchoring proteins by enzymatic steps, leading to a superior transplantation method for keratinocytes.

Adult↗