Biomedical subjects

M Voigt

Publications and source records attributed to M Voigt.

At least 19 recordsLinked to original sources

PubMed2007

Risk factors for hepatitis C fibrosis: a prospective study of United States veterans compared with nonveterans.

Chronic hepatitis C virus (HCV) infection causes cirrhosis in many infected patients; however, a better understanding of the risk factors for fibrosis progression in high HCV prevalence groups such as US veterans is needed. We wished to compare the demographic, clinical characteristics, and independent variables that influence fibrosis in US veterans vs nonveterans with chronic HCV. HCV-seropositive US veterans (n = 459) and nonveterans (n = 395) prospectively completed a detailed medical, social and occupational questionnaire. Clinical factors for progressive liver disease were compared between veterans and nonveterans and fibrosis stage assessed on liver biopsies (168 veterans and 208 nonveterans). Using polychotomous logistic regression, fibrosis was analysed as both a progressive and categorical outcome to determine independent risk factors for both patient groups. Although veterans were significantly older and had higher lifetime alcohol consumption than nonveterans, their median fibrosis scores did not differ from nonveterans. By univariate analysis, alanine aminotransferase, necroinflammatory activity (NIA), and cryoglobulin positivity were associated with fibrosis in veterans and nonveterans (P < 0.05, all comparisons), whereas steatosis was associated with fibrosis only in nonveterans (P < 0.0001). By multivariate analysis, NIA was an independent risk factor for fibrosis in both groups (P < 0.01). However, fibrosis in nonveterans was also independently associated with steatosis, significant alcohol consumption and age (P < 0.04, all comparisons). Independent risk factors for fibrosis vary among high HCV prevalence groups such as veterans when compared with nonveterans. Understanding specific patient cohort effects is important for determining independent risk factors for disease progression in chronic HCV infection.

Adult↗

PubMed2006

Sex-specific differences in birth weight due to maternal smoking during pregnancy.

INTRODUCTION: We investigated the sex-specific risk of maternal smoking during pregnancy on the birth weight and the proportion of small-for-gestational-age (SGA) newborns in 888,632 (49.9%) of 1,815,318 singleton births (ca. 80% of all singleton births in Germany from 1995 to 1997) in whom data on maternal cigarette consumption were available. RESULTS AND DISCUSSION: Newborns below the 10th percentile for weight and duration of pregnancy were classified SGA. Maternal smoking during pregnancy lowers the mean birth weight and increases the risk of SGA newborns. The negative effect depends on the daily number of cigarettes consumed, and is greater in girls than in boys. In non-smokers, 9.8% of the newborns were SGA, with a sex-ratio of females:males=1, but this percentage increased with increasing number of cigarettes consumed (p<0.001), as did the sex-ratio, i.e. the negative effect of smoking on growth was greater in girls than in boys. In mild smokers (1-5 cigarettes/day), the risk of giving birth to an SGA girl was 1.7275-fold (95% CI: 1.7266-1.7284) above normal, but was 1.7143-fold (95% CI: 1.7137-1.7150) in boys. More than 21 cigarettes/day increased the risk of SGA 3.15-fold for a boy, but 3.51-fold for a girl (p<0.001). CONCLUSION: In conclusion, particularly in heavy smokers, the negative effect of maternal smoking during pregnancy on the mean birth weight and risk of SGA is significantly greater in newborn girls than in newborn boys.

Birth Weight↗

PubMed2006

Analysis of retinal flecks in fundus flavimaculatus using optical coherence tomography.

BACKGROUND/AIM: Retinal flecks are commonly observed in both Stargardt disease and fundus flavimaculatus (FFM). The aim was to determine the precise localisation of these flecks within the retinal layers using Stratus optical coherence tomography (OCT). METHODS: A prospective observational case series. A complete ophthalmological examination, including autofluorescence, fluorescein angiography (FA), and Stratus OCT (Carl Zeiss) was performed in 49 eyes of 26 consecutive patients with FFM. Six to 12 Stratus OCT linear scans focused on the retinal flecks were performed in each eye. RESULTS: The age at presentation ranged from 23 years to 71 years and visual acuity ranged from 20/20 to 20/400. Hyper-reflective deposits classified into two types were observed on Stratus OCT: type 1 lesions (94% of eyes) presented as dome-shaped deposits located in the inner part of the retinal pigment epithelium (RPE) layer and type 2 lesions (86% of eyes) presented as small linear deposits located at the level of the outer nuclear layer and clearly separated from the RPE layer. CONCLUSIONS: Stratus OCT is a non-invasive instrument that provides new information on the location of flecks in FFM. The location of type 2 lesions is quite unusual among macular dystrophies; OCT may therefore be useful in the diagnosis of retinal flecks in some cases of FFM.

Adult↗

PubMed2006

A cyclosporine-based immunosuppressive regimen may be better than tacrolimus for long-term liver allograft survival in recipients transplanted for hepatitis C.

UNLABELLED: Rapid recurrence of severe hepatitis C (HCV) after liver transplantation is a major barrier to survival of the transplanted liver. While cyclosporine (CsA) in vitro has been shown to suppress HCV replication, an effect is not seen with tacrolimus (Tac). Evidence is inconsistent whether or how this translates to clinical practice. To expand the evidence on this issue, we analyzed graft survival and histological outcomes after liver transplantation for HCV hepatitis. METHODS: Using our longitudinal database (1991 onward) graft outcomes for all liver transplant recipients with HCV were evaluated (105 grafts in 97 patients). Severe activity, severe fibrosis, and graft survival were analyzed. All liver biopsies were scored (blinded) according to the Ludwig scale. Immunosuppression was based on prednisone and a calcineurin inhibitor (Tac n = 89, 85%; CsA n = 15, 14%). Comparisons of outcomes using CsA versus Tac therapy were done using survival analysis via the log-rank test. RESULTS: Graft survival was significantly better in the CsA group. Although there was no apparent difference in severe activity (grade 2), there was a statistically significant difference in graft survival without fibrosing cholestatic hepatitis (P = .01) and a trend toward a difference in fibrosis-free survival (P = 0.1). The rate of sustained response to antiviral therapy was twice as high in the CsA group, 50% versus 22% (P = 0.16; NS). CONCLUSIONS: Graft survival in liver transplant recipients with HCV may be greater with CsA-based immunosuppression. There may also be a lower rate of fibrosing cholestatic hepatitis in this group.

Biopsy↗

PubMed2006

Obesity, voracity, and short stature: the impact of glutamate on the regulation of appetite.

BACKGROUND: World-wide obesity has risen to alarming levels. We present experimental support for a new and very challenging hypothesis linking obesity, voracity, and growth hormone (GH) deficiency, to the consumption of elevated amounts of the amino-acid glutamate (GLU). Supraphysiological doses of GLU are toxic for neuronal cells. METHODS: Human data were obtained from 807,592 German conscripts born between 1974 and 1978, and from 1,432,368 women of the German birth statistics (deutsche Perinatalerhebung) 1995-1997. The effects of orally administered monosodium glutamate (MSG) were investigated in 30 pregnant Wistar rats and their offspring. Pregnant animals either received no extra MSG, or 2.5 g MSG, or 5 g MSG per day, up to the end of the weaning period. In all, 2.5 g, respectively 5 g, MSG accounted for some 10%, respectively 20%, of dry weight of the average daily food ration. After weaning, MSG feeding was continued in the offspring. FINDINGS: Morbid obesity associates with short stature. Average stature of conscripts progressively declines when body mass index increases above 38 kg/m2. Also morbidly obese young women are shorter than average though to a lesser extent than conscripts. Oral administration of MSG to pregnant rats affects birth weight of the offspring. Maternal feeding with 5 g MSG per day results in severe birth weight reduction (P<0.01). Weight increments remain subnormal when MSG feeding to the mothers is maintained during weaning (P < 0.01). GH serum levels are affected in animals that received MSG during prenatal life via maternal feeding. Animals that are kept on high MSG diet (5 g MSG per day) continue to show serum GH levels that are as low or even lower than those of MSG injected animals (P < 0.05), both at day 30 and at day 90 of life. Animals that were kept on medium MSG diet (2.5 g MSG per day) showed low serum GH levels at day 30 of life (P < 0.01), but seemed to partially recover before day 90. Almost identical results were observed in IGF-1 serum levels. Oral MSG resulted in dose dependent voracity. The animals fed 5 g MSG per day increased water uptake by threefold (P < 0.01), and food uptake by almost two-fold (P < 0.01). The influence of MSG is in general more marked in males than in females. INTERPRETATION: GLU is a widely used nutritional substance that potentially exhibits significant neuronal toxicity. Voracity, and impaired GH secretion are the two major characteristics of parenterally administered GLU-induced neuronal damage. GLU maintains its toxicity in animals even when administered orally. Males appear to be more sensitive than females. The present study for the first time demonstrates, that a widely used nutritional monosubstance--the flavouring agent MSG--at concentrations that only slightly surpass those found in everyday human food, exhibits significant potential for damaging the hypothalamic regulation of appetite, and thereby determines the propensity of world-wide obesity. We suggest to reconsider the recommended daily allowances of amino acids and nutritional protein, and to abstain from the popular protein-rich diets, and particularly from adding the flavouring agents MSG.

Adult↗

PubMed2005

Morbid obesity is associated with short stature.

Body height and body mass index (BMI) were obtained from 807,592 German conscripts born between 1974 and 1978, aged 19-20 years. The conscripts had either completed Gymnasium (secondary school, more than 10 years, A-level), Realschule (secondary school, 10 years, O-level), or Hauptschule (elementary school, 9 years). Maternal data on body height and weight at the beginning of pregnancy from 1,432,368 women were obtained from the German birth statistics (deutsche Perinatalerhebung) 1995-1997. Morbid obesity is associated with short stature. Regardless of school education, average stature of conscripts progressively declines by up to 10 cm when the BMI increases above 38 kg/m2. In addition, morbidly obese young women are shorter than average, though the impact of overweight on adult stature appears to be less pronounced than in males.

Adult↗

PubMed2004

[German Environmental Survey for Children (GerES IV). Environmental module of KiGGS. Part 2: The first year of field work].

The field work of the German Environmental Survey for Children (GerES IV) was started nationwide in May 2003. The survey is a module of the National Health Interview and Examination Survey for Children and Adolescents (KiGGS). This environmental survey includes a representative subsample of 1800 children from the 18,000 participants of the KiGGS who are being examined regarding health-relevant environmental exposure. The investigational programme of the survey was tested successfully in a pilot study (pretest) the results of which contributed to the optimisation of the main study. The field work is essentially done by the environmental interviewer of the three teams of the KiGGS. Preparation, organization and accompaniment of the work is done by the coordination centre of the Robert Koch Institute on Federal Environmental Agency (UBA) instructions. Funding agencies are the Federal Ministry of Education and Research (BMBF) and the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU). Both the KiGGS and the environmental module are evaluated by internal and external quality assurance during the whole study period (May 2003-May 2006). Up to now the established teams have done their field work very well and the coordination of the overall project by the Robert Koch Institute works well, too. A total of 722 subjects had taken part in the GerES IV by July 2004.

Adolescent↗

PubMed2004

Modification of stretch tolerance in a stooping position.

A stooping (slump) position is believed to add tension to the nerve tissue complex. This study was designed to determine whether this position would have an effect on the stretch tolerance in a passive knee extension. Thirteen healthy individuals were tested. The knee extension was stopped by the subjects at "onset of pain". Joint range of motion and passive resistance to the extension were recorded in four test situations: upright sitting and stooping position, with the ankle joint in either the neutral or maximal dorsi-flexed position. A significant decrease in range of motion was seen when shifting from upright to stooping position: Delta angle -2.4 degrees (P<0.01). According to this, the passive tissue tension was accepted at significantly lower values in stooping position: Delta torque -1.2 N m (P<0.01). Testing with maximal dorsi-flexion of the ankle showed more pronounced changes: Delta angle -3.4 degrees (P<0.001); Delta torque -2.3 N m (P<0.001), but the effect of foot position was not significant. Knee joint range of motion was acutely diminished in a stooping position. Thus, stretch tolerance was affected by manipulation of structures, which were not directly mechanically related to this joint. An influence from the nerve tissue complex must be considered to be a factor when describing the mechanisms behind altered stretch tolerance.

Adult↗

PubMed2003

Nucleation and growth of molecular organic crystals in a liquid film under vapor deposition.

We report on the nucleation and growth of tetracene in a thin liquid film which is continuously supersaturated by vapor deposition of molecules onto the film. In a first stage, nucleation and fast anisotropic two-dimensional dendritic growth occurs. In a second stage, the dendrites coarsen into pallet-shaped crystals. These are highly oriented with respect to the plane of the liquid film and reach a lateral size of several 100 microm. The two-dimensional growth mode is explained by the confined growth geometry in the liquid in combination with the anisotropy of the crystal structure.

Journal Article↗

PubMed2002

Down-regulation of NOSII gene expression by iontophoresis of anti-sense oligonucleotide in endotoxin-induced uveitis.

Transcorneoscleral iontophoresis was used to enhance ocular penetration of a 21-bp NH(2) protected anti-NOSII oligonucleotides (ODNs) (fluorescein or infrared-41 labeled) in Lewis rats. Both histochemical localization and acrylamide sequencing gels were used. To evaluate the potential to down-regulate NOSII expression in the rat model of endotoxin-induced uveitis (EIU), anti-sense NOSII ODN, scrambled ODN or saline were iontophorezed into these animals' eyes. Iontophoresis facilitated the penetration of intact ODNs into the intraocular tissues of the rat eye and only the eyes receiving ODNs and electrical current demonstrated intact ODNs within the ocular tissues of both segments of the eye. Iontophoresis of anti-NOSII ODN significantly down-regulated the expression of NOSII expression in iris/ciliary body compared to the saline or scrambled ODN treated eyes. Nitrite production was also significantly reduced in the anti-NOSII applied eyes compared to those treated with saline. Using this system, intraocular delivery of ODNs can be significantly enhanced increasing the potential for successful gene therapy for human eye diseases.

Animals↗

PubMed2002

Human recombinant EGF protein delivered by a biodegradable cell transplantation system.

We have previously shown a new approach to expand cultured human keratinocytes and reconstitute the epidermis in full-thickness wounds using a new microsperical transport system. This was a new approach to increase the cell yield for seeding without altering the anchoring proteins by enzymatic steps. That time we used Cytodex 3 which failed to be degraded and induced an inflammatory reaction in a t-cell-deficient organism. Therefore, we have investigated another microcarrier consisting of PLGA, which is a well-known carrier material for cell culture and transplantation. After coating the PLGA carrier with gelatine the seeding time of viable cells reached 4 h and the cell gain after 7 days of spinner culture was 16-fold. At 14 days after transplantation, we could detect a new stratified epithelium in our full-thickness wound healing model. Because cytokines play a major role in wound healing, we loaded this carrier material with different concentrations of rhEGF, showing a dose dependent release of the protein in vitro and in vivo. This result might lead to a different approach in the treatment of wounds.

Absorbable Implants↗

PubMed2001

Suprahepatic venacavaplasty (cavaplasty) with retrohepatic cava extension in liver transplantation: experience with first 115 cases.

BACKGROUND: We first introduced the orthotopic liver transplantation utilizing cavaplasty technique in 1994. This paper describes the surgical technique and assesses the outcome of the cavaplasty OLT. METHODS: The cavaplasty procedure was used in 115 consecutive orthotopic liver transplantations, including six left lateral and two right lobe transplantations, between November 1994 and September 2000. Fifty-three (66.3%) transplantations required femoro-axillary veno-venous bypass in the initial 4 years, whereas only eight (22.9%) needed VB in the subsequent 2 years. Conversion to piggyback or standard technique was not necessary in any patient. RESULTS: Median results are as follows: operative time 4.5 hr, warm ischemia time 25 min, and blood transfused (packed red blood cells) 6 units. These findings did not differ between first transplantation and retransplantation. There were no perioperative deaths related to the cavaplasty technique. No hepatic venous outflow obstruction was observed, including living-related OLTs. No patient required postoperative hemodialysis for acute renal failure. The median intensive care and hospital stays were 2 days and 10 days, respectively. CONCLUSIONS: The cavaplasty technique requires no retrocaval, hepatic vein, or short hepatic vein dissection, and the inferior vena cava can be preserved, which provides advantages for hepatectomy and easy hemostasis, especially during retransplantation. The wide-open triangular caval anastomosis is easy to perform, allowing short implantation time and size matching and avoiding outflow obstruction. The short implantation time reduces the need for veno-venous bypass. Our experience indicates that the cavaplasty technique can be applied to all patients and is justified by minimal technical complications.

Adolescent↗

PubMed2001

Tissue engineering in plastic reconstructive surgery.

Tissue engineering (TE) is a new interdisciplinary field of applied research combining engineering and biosciences together with clinical application, mainly in surgical specialities, to develop living substitutes for tissues and organs. Tissue engineering approaches can be categorized into substitutive approaches, where the aim is the ex vivo construction of a living tissue or organ similar to a transplant, vs. histioconductive or histioinductive concepts in vivo. The main successful approaches in developing tissue substitutes to date have been progresses in the understanding of cell-cell interactions, the selection of appropriate matrices (cell-matrix interaction) and chemical signalling (cytokines, growth factors) for stimulation of cell proliferation and migration within a tissue-engineered construct. So far virtually all mammalian cells can be cultured under specific culture conditions and in tissue specific matrices. Future progress in cell biology may permit the use of pluripotent stem cells for TE. The blueprint for tissue differentiation is the genome: for this it is reasonable to combine tissue engineering with gene therapy. The key to the progress of tissue engineering is an understanding between basic scientists, biochemical engineers, clinicians, and industry.

Animals↗

PubMed2001

[Minimally invasive surgical therapy of gynecomastia: liposuction and exeresis technique].

INTRODUCTION: A number of techniques are available for the correction of gynecomastia. Nonscarring sparing methods are preferred, and the minimally invasive technique is to use liposuction for the gland and the fatty tissue exclusively. In this retrospective study we present our experience with a combination of liposuction and subsequent resection of the remaining gland. METHODS: Sixty-two patients (112 breasts) were surgically treated for gynecomastia from January 1996 and September 2000. From 1996 to 1997 all patients suffering from gynecomastia grade Simon I-II were treated by the method described by Rosenberg and Stark, which is exclusively suction of the fatty and glandular tissue. In a retrospective chart study a high recurrence rate was found in these patients. Subsequently we changed our technique to liposuction of the fatty tissue followed by sharp excision of the glandular tissue through the incision made for the liposuction cannula in the submammary fold. RESULTS: Suction alone was not sufficient to remove the glandular tissue; the rate of recurrence after suction was 35%. When sharp resection of the glandular tissue was carried out after the liposuction the recurrence rate dropped to under 10%. In total our complication rate was 50% including minor sequelae. The most frequent complication was unacceptable scarring of the nipple-areola complex. Hypesthesia of the nipple-areola occurred in 13.4% of the patients. CONCLUSION: The combination of liposuction and resection of the glandular tissue is a minimally invasive correction that can be used in all cases of gynecomastia grade Simon I-II.

Adult↗

PubMed2001

Intravitreal acetylsalicylic acid in silicone oil: pharmacokinetics and evaluation of its safety by ERG and histology.

BACKGROUND: A new method of intravitreal drug delivery of acetylsalicyclic acid (AS) in silicone oil was investigated for safety and for its pharmacokinetics in the posterior pole of the eye. METHODS: The AS was mixed in silicone oil to a concentration of 1.67 mg/ml. After vitrectomy, 15 NZW rabbits received an intravitreal injection of AS/silicone oil suspension. Clinical examination, pre- and postoperative electroretinography (ERG) and histology were performed. The pharmacokinetics of the distribution of salicylic acid was determined by HPLC analysis at 6 h, 24 h and 5 days in optic nerve, retina, choroid, vitreous, and blood. RESULTS: Clinical examination and histology revealed no adverse effects or signs of toxicity. The ERGs showed no significant difference between the pre- and postoperative results. The salicylic acid concentrations demonstrated peak values in the residual vitreous (640.0 micrograms/ml), choroid (446.0 ng/mg) and retina (281.3 ng/mg) at 6 h. At 24 h, the salicylic acid concentration decreased to 20.9 micrograms/ml in the residual vitreous and to 38.5 ng/mg in the retina. At 5 days the retinal level was still 48.1 ng/mg. CONCLUSIONS: AS delivery by intravitreal administration of loaded silicone oil is a safe method and results in high concentrations of salicylic acid in the posterior segment of the eye while maintaining low blood levels.

Animals↗

PubMed2001

Functional postural responses after perturbations in multiple directions in a standing man: a principle of decoupled control.

The objective of this study was to assess functional postural responses by analyzing the net joint torques (NJT) in the ankles and the hips resulting from perturbations delivered in multiple directions to subjects standing quietly. A total of eight subjects were standing on two force platforms while an apparatus randomly delivered controlled perturbations at the level of the pelvis in eight directions: anterio-posterior (AP), medio-lateral (ML), and four combinations of these principal directions. Perturbations were repeated five times in each direction for six conditions (i.e., three different perturbation strengths and three different feet orientations). The comparison of the averaged ankle sum NJT (AP) responses showed that the time courses of the responses elicited by a perturbation acting only in the AP direction were identical to those elicited by a combination of two corresponding AP and ML perturbations. In contrast the observed averaged ankle NJT (ML) responses did not follow the same similarity. The comparison of the averaged ankle and hip sum NJT (ML) responses revealed that the time courses of the responses elicited by a perturbation acting only in the ML direction were identical to those elicited by a combination of two corresponding AP and ML perturbations. These findings were invariable of the experimental conditions and were consistent among all the eight subjects. Thereby, we conclude that the ankle sum NJT (AP) and the ankle and hip sum NJT (ML) are the global variables being controlled. This shows that CNS controls the recovery from the multiple direction perturbations of moderate strength by decoupling the AP-ML postural space into two orthogonal directions (AP and ML).

Adult↗

PubMed2001

Muscle recruitment by the min/max criterion -- a comparative numerical study.

This paper introduces the min/max criterion for simulation of muscle recruitment in multiple muscle systems. The criterion is introduced and justified by comparison to two known criterion types: the polynomial criterion and the soft saturation criterion. The comparison is performed on a planar three-muscle elbow model performing a dumbbell curl. A generalized form of the soft saturation criterion is introduced, and it is shown that the min/max criterion can be interpreted as the limit of the classical criteria when the exponents in their mathematical expressions approach infinity. We finally show how the min/max criterion can be cast into a form that allows for efficient and robust numerical solution by linear programming. It is concluded that the min/max criterion possesses a number of attractive physiological as well as algorithmic advantages.

Algorithms↗

PubMed2001

Moment dependency of the series elastic stiffness in the human plantar flexors measured in vivo.

The moment dependency of the series elastic stiffness (SES) in the human plantar flexors was investigated in vivo with the quick release method. At an ankle moment of 100 N m produced with either voluntary or electrical stimulation we found non-significantly different SES of 506+/-72 and 529+/-125 N m rad(-1), respectively. It has recently been proposed that the amount of series elastic tissue involved in plantar flexion changes with the moment level produced by the plantar flexors (Hof, J. Biomech 31 (1998) 793). However, our results indicate that the amount of series elastic tissue involved in plantar flexions remained constant with changing moment levels. We therefore propose that the series elastic component (SEC) in human plantar flexors act as one structure or rather one combination of anatomical structures which is engaged at all muscle activation levels, and that the mechanical properties (i.e. the stress-strain function) are determined by the combined tissue mechanical properties. Additionally, our results demonstrated that the SES in the human plantar flexors at moments levels up to about isometric maximum did not reach an asymptote where the stiffness is independent of moment, i.e. SEC of the plantar flexors is, during many daily activities, loaded for the greatest part in the non-linear part of the stress-strain function.

Adult↗