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Biomedical subjects

J Wiltfang

Publications and source records attributed to J Wiltfang.

At least 91 records · Page 5Linked to original sources
PubMed2000

[Intra-individual comparison of alpha- and beta-TCP ceramics in an animal experiment].

In the quest for bioinert adaptable alloplastic materials, TCP ceramics have gained a new application in craniofacial bone substitutes. Therefore, a histomorphological, intraindividual, comparative study was conducted on seven adult Goettingen miniature pigs (GMP) to analyze the difference of the degradation and remodelling processes of alpha-TCP and beta-TCP in critical size defects of the proximal tibiae. In addition, primary insertion of dental implants followed to study osseous integration. The critical size defects, which were created in the proximal tibiae in GMPs, were filled on the left side with beta-TCP and on the right side with alpha-TCP. Two GMPs were used as control group. After 4-68 weeks of investigation, the GMPs were sacrificed by narcosis. The histological investigation showed that these ceramics have an osteoconductive effect. It was noted that ossification proceeds centripetally. It could be demonstrated that the degradation of the materials follows a hydrolytical process and that the intratrabecular integrated ceramic remnants follow a dynamic remodelling process. Within 68 weeks after implantation, 90% of the TCP granulae were degraded. Macrophages were found in the marrow space, containing microparticles of TCP, especially after alpha-TCP implantation. In conclusion, defined degradation of these ceramics allows early functional bone regeneration with an additional undisturbed biofunctional unisotrop orientation of new trabeculae. Furthermore, dental implants should be inserted 5-6 months after TCP implantation.

Animals↗
PubMed2000

[Possibilities of computer graphics simulation in orthopedic surgery].

BACKGROUND: In addition to standard X-rays, photographic documentation, cephalometric and model analysis, a computer-aided, three-dimensional (3D) simulation system has been developed in close cooperation with the Institute of Communications of the Friedrich-Alexander-Universität Erlangen-Nürnberg. With this simulation system a photorealistic prediction of the expected soft tissue changes can be made. Prerequisites are a 3D reconstruction of the facial skeleton and a 3D laser scan of the face. After data reduction, the two data sets can be matched. Cutting planes enable the transposition of bony segments. The laser scan of the facial surface is combined with the underlying bone via a five-layered soft tissue model to convert bone movements on the soft tissue cover realistically. CONCLUSION: Further research is necessary to replace the virtual subcutaneous soft tissue model by correct, topographic tissue anatomy.

Cephalometry↗
PubMed2000

[Continuous bone distraction with the help of a microhydraulic cylinder].

Distraction osteogenesis of the mandible is one treatment option in mandibular hypoplasia. Usually, a non-continuous distraction mode is applied. The aim of the present study was to establish continuous bone distraction using a microhydraulic cylinder. Using a submandibular approach, the mandible was dissected subperiostally on one side in four mini-pigs; corticotomy was performed and the microhydraulic cylinder fixed with two bicortical screws. The hydraulic tube was connected with an automatic hydropneumatic injector system. Following 7 days at rest, a continuous distraction of 1.5 mm per day was performed for 14 days. After 2 and 4 weeks postoperatively, the animals were killed and X-rays taken. The mandible was then removed en bloc and microscopic evaluation of the sections was performed. The microhydraulic cylinder was easy to apply and to handle. The continuous stimulus did induce direct mineralisation of longitudinal oriented collagenous fibre bundles. Bony regeneration seems to be accelerated, which might reduce the postoperatively stabilizing phase.

Animals↗
PubMed2000

[Distraction osteogenesis of the mandible in craniofacial abnormalities].

In recent years, lengthening the human mandible by distraction osteogenesis has become an accepted treatment to correct severe mandibular hypoplasia. Using intraoral unidirectional and extraoral bidirectional distraction devices we report about our experiences and results in the application of the bone distraction technique in four selected cases of syndromal disease, including various forms of mandibular hypoplastic malformations. The patients involved were a boy with Pierre Robin syndrome, a girl with unilateral facial hypoplasia in Goldenhar's syndrome, a case with Nager's syndrome, and a rare case of midline deficiency caused by partial deletion of chromosome 18 (18p-syndrome). The distraction period lasted from 6 to 30 days and new bone formation, ranging from 6 to 28 mm, was achieved.

Adolescent↗
PubMed2000

Endoscopic and ultrasonographic evaluation of the maxillary sinus after combined sinus floor augmentation and implant insertion.

OBJECTIVE: The aim of our study was a radiographic, endoscopic, and ultrasound follow-up of the maxillary sinus comparing 2 techniques of sinus floor augmentation. STUDY DESIGN: Sonograms, radiographs (Waters' view) of the sinuses, and endoscopy served before and during surgery to evaluate the maxillary sinus. One week after the operation, ultrasound and radiograph follow-up (Waters' view) were carried out. Six months after the operation, we performed an ultrasound follow-up along with uncovering the implants. If any pathologic condition was found, we took another x-ray film of the sinuses, performed another endoscopic examination, or both. RESULTS: In 23 of 63 patients, healing was uneventful. Waters' view revealed opacification of the maxillary sinus 1 week after surgery in 40 cases when the "window technique" was used. Sinusitis occurred 3 times, as a result of migration of bone chips in 2 patients. We lost 11 of 132 inserted implants during the healing and loading periods. CONCLUSION: Endoscope-controlled sinus floor augmentation may lower the complication rate in a remaining height of the jaws between 4 and 8 mm. In our group of patients, we proved by endoscopic examination that migration of cancellous bone sequestra was the reason for sinusitis. In case of infected bone grafts with antral symptoms, sinoscopy allowed debridement and removal of a sequestrum.

Alveolar Ridge Augmentation↗
PubMed2000

Creutzfeldt-Jakob disease and oxidative stress.

OBJECTIVES: Substantial evidence supports the hypothesis that oxygen free radicals are involved in various neurodegenerative disorders. To assess the presence of oxidative stress in Creutzfeldt-Jakob disease (CJD) we examined the concentrations of malondialdehyde (MDA) as an established marker of lipid peroxidation. MATERIAL AND METHODS: MDA was quantified by high performance liquid chromatography (HPLC) in cerebrospinal fluid (CSF; n=12) and in serum (n=11) samples of CJD patients and healthy controls (n = 15). RESULTS: Mean values in healthy controls: 2.56 nmol/ml +/- 0.46 (CSF) and 1.94 nmol/ ml +/- 0.67 (serum); mean values in CJD patients: 2.64 nmol/ml +/- 0.67 (CSF) and 1.68 nmol/ml +/- 0.79 (serum). No significant (P>0.05) difference between CJD patients and controls was observed. CONCLUSIONS: The results indicated that the CSF and serum of CJD patients showed no higher endogenous levels of MDA as compared to normal healthy controls. These findings provide no evidence for an additional role of oxidative stress in the pathogenetic mechanism underlying CJD neurodegeneration.

Biomarkers↗
PubMed2000

Systemic and splanchnic endothelin-1 plasma levels in liver cirrhosis before and after transjugular intrahepatic portosystemic shunt (TIPS).

AIMS/BACKGROUND: Endothelin-1 (ET-1) may be a mediator for portal hypertension in liver cirrhosis. The aim of the present study was to determine the concentrations of ET-1 in the systemic and splanchnic circulation before and after reduction of portal hypertension by transjugular intrahepatic portosystemic shunt implantation (TIPS). METHODS: Plasma concentrations of immunoreactive ET-1 were measured in peripheral venous blood samples from 25 patients with liver cirrhosis before and at 1, 3, 9 and 15 months after TIPS. Furthermore, acute effects of TIPS on ET-1 were studied in plasma samples from the hepatic vein, the portal vein 30 minutes before and after TIPS and in the femoral artery (only after TIPS) in a subgroup of 15 patients. In addition, the portocaval pressure gradient was determined before and after TIPS. RESULTS: Before TIPS peripheral venous plasma ET-1 concentrations (n=25; median 4.2 pg/ml; range 1.9-14.7) were significantly increased in patients with refractory ascites (n=7; median 7.8, range 3.5 14.7) compared to patients with repetitive bleeding (n=18; median 3.4; range 1.9-7.1) (p=0.003). Furthermore, peripheral ET-1 concentrations correlated with the degree of liver dysfunction according to the Child-Pugh classification (Spearman's r=0.46; p=0.02). Following TIPS, peripheral ET-1 concentrations remained unchanged during a follow-up of 15 months. Before TIPS, a positive gradient of ET-1 concentrations from portalvenous to hepatovenous and peripheral venous levels was found (p<0.03). Immediately after TIPS, arterial ET-1 concentrations reached markedly increased levels in individual patients (88, 92 and 103 pg/ml). Severe systemic reactions to these high levels were not observed. Peripheral venous, hepatovenous and portalvenous ET-1 concentrations did not correlate with portocaval pressure gradients. CONCLUSION: Cirrhotic patients demonstrated unchanged peripheral venous ET-1 concentrations up to 15 months after TIPS. Portal congestion was associated with increased ET-1 levels in the prehepatic splanchnic area. The effect of portal decompression on splanchnic and systemic ET-1 levels deserves further investigation.

Adult↗
PubMed2000

A new distraction device to compare continuous and discontinuous bone distraction in mini-pigs: a preliminary report.

Callus-distraction has become an accepted procedure to lengthen hypoplastic mandibles in humans. Extra- and intraoral devices have been applied successfully. Systematic studies have proven the importance of direction, stability, rate and frequency in callus-distraction. In an experimental animal study a newly developed intraoral microhydraulic osteodistractor was tested. Initially the pressures necessary to distract the mandible in mini-pigs were recorded in discontinuous callus-distraction. These results were used to perform continuous bone distraction. Besides testing the new distractor and evaluating the distraction pressures, the aim of the study was to prove that direct bone growth occurred without preceding cartilage formation. Clinical and microscopic results are presented.

Animals↗
PubMed2000

[Diagnostic steps in Alzheimer dementia before treatment with new antidimentives].

The dementia of the Alzheimer type (DAT) is a chronic neurodegenerative illness. It will continue to increase because of rising life expectancy in the industrialized countries. Apart from the physicians interest to treat, there is also an economically justified interest to reduce the disease progression in this group of patients. The main intention of the treating physicians is to keep their patients independent as long as possible. Up to now Alzheimer's disease can only be treated symptomatically. The verified diagnosis of DAT still depends on the neuropathological investigation of brain tissue. Therefore the clinical diagnosis of DAT during lifetime should be supported by chemical analysis of typical changes in the cerebrospinal fluid (CSF) at an early stage. Meanwhile, several therapeutics with proven effectiveness in clinical studies are certified for the symptomatic treatment of DAT. However, these therapeutics are still relatively expansive. Due to this fact the clinical diagnosis of DAT should be supported by clinical-chemical markers before the beginning of such a treatment. In this paper we present the diagnostic steps in dementia patients, who are examined in our departments. Patients suspicious of DAT always are asked for a spinal tap in addition to other diagnostic tools. In case of a typical clinical constellation, the exclusion of a primarily vascular dementia as well as the proof of decreased A beta 1-42 peptides and an increased tau protein in CSF we recommend the new drugs for DAT as meaningful and justified therapeutics to yield optimal treatment.

Aged↗
PubMed2000

A prospective PMS study to validate the sensitivity for change of the D-scale in advanced stages of dementia using the NMDA-antagonist memantine.

The present postmarketing surveillance (PMS) study is the first large scale systematic and prospective clinical trial of pharmacotherapeutic intervention in advanced stages of dementia. Within a validation program this study aimed at demonstrating the sensitivity of the D-Scale of change (DS-C) for measuring ADL-function. Efficacy of treatment with the NMDA-antagonist memantine was investigated in 531 patients with advanced dementia employing a parallel group design that stratified patient cohorts by severity according to GDS stages (Reisberg, 1992). Efficacy was determined on two independent levels: by the assessment of the physicians' Clinical Global Impression of Change (CGI-C) at the end of a 6-week observation period, and by the assessment of change in elementary ADL-functions by the caregivers using the D-Scale-of-Change. With the D-Scale-of-Change the caregivers can assess a change in broad functional items, i.e. cognitive and motor functions and also elementary functions of daily life. The effect size of this improvement increased constantly during the observation period. Even in patients of GDS stage 7 an improvement could be measured. These results were also seen by the physicians, who recorded an overall clinical improvement in 75.5% of the patients after 6 weeks. Tolerability evaluations resulted in the ratings "very well" by 59.5% or "well" by 35.0% of the patients. No serious adverse drug reactions occurred. A correlation analysis demonstrated a high congruency of both assessments. Furthermore, the observed time course of these improvements paralleled with the time course of symptomatic benefit by effects of memantine that had been repeatedly demonstrated in randomised, double-blind, placebo-controlled studies in mild to moderate dementia. Together with the evaluation of the scale-properties of the D-Scale for assessment of severity the D-Scale and the D-Scale-of-Change can be regarded as validated.

Activities of Daily Living↗
PubMed2000

Boxing and running lead to a rise in serum levels of S-100B protein.

Permanent neurological dysfunction is the primary medical concern of boxing. Recently it was reported that patients presenting elevated levels of the glial protein S-100B in serum after minor head injuries are more prone to develop neuropsychological deficits than patients with lower levels of S-100B protein. We assessed this protein before and after amateur boxing competitions (n = 10) and sparring bouts (n = 15). In several control groups, we investigated S-100B levels of participants before and after a 25 km race (n = 11), jogging (10 km, n = 12), short-term running (n = 12), and heading footballs (n = 12). There was an increase in S-100B protein after boxing and the running disciplines but not after ergometer cycling or soft heading of footballs. The increase in S-100B protein concentrations due to competitive boxing and after the 25 km race was significantly higher than that after performing other disciplines (p < 0.001). There was no significant difference between the increases caused by sparring and the running disciplines (p = 0.21). The number and severity of the strikes to the head correlated significantly with the increase in the S-100B protein levels. Levels of S-100B protein known to be associated with neuropsychological deficits were not reached in our study. In professional boxing, much higher levels are to be expected and would be worthy of investigation.

Adolescent↗
PubMed2000

Biodegradable miniplates (LactoSorb): long-term results in infant minipigs and clinical results.

Metallic plates are known for their passive intraosseous transmission in the growing skull. To avoid plate removal, resorbable material with strength comparable to that of metallic plates and predictable resorption would be desirable. This should be accomplished without causing inflammatory complications and foreign body reactions often seen with highly crystalline poly-L-lactic acid or pure polyglycolic acid implants. In an animal experiment in four young Göttingen minipigs, the resorbable poly-L-lactic acid/polyglycolic acid copolymer LactoSorb was tested previously. In addition to testing the mechanical properties, the process of degradation and sub- versus epi- or supraperiosteal application of the miniplate device LactoSorb was evaluated using a frontal cranioosteoplasty model. Furthermore, LactoSorb was used in 10 patients with craniosynostosis or craniofacial trauma. During degradation, the absorbable poly-L-lactic acid/polyglycolic acid miniplates acted like metal plates because they also displayed passive intraosseous transmission in the growing animal model. Degradation took 12 to 18 months and was not delayed by bony incorporation. Their mechanical properties proved to be sufficient in craniofacial surgery. Epiperiosteal plating prolonged the passive intraosseous transmission effect during the first 3 months after surgery. There were no major inflammatory reactions seen in the experimental and/or in the clinical study.

Absorbable Implants↗
PubMed2000

Histomorphometric analysis of irradiated recipient vessels and transplant vessels of free flaps in patients undergoing reconstruction after ablative surgery.

The aim of the study was to investigate, histomorphometrically, quantitative and qualitative changes in irradiated neck recipient vessels and transplant vessels used for microsurgical anastomoses in free flaps in patients undergoing preoperative radiotherapy and chemotherapy. In 55 patients receiving 42 radial forearm flaps, 6 latissimus dorsi flaps, 6 osteomyocutaneous fibula grafts and 1 lateral arm flap, a total of 220 vessels were obtained from neck recipient vessels and transplant vessels during anastomosis. Three groups were formed: Group 1 (16 patients) treated with no radiotherapy or chemotherapy; Group 2 (20 patients) treated with preoperative irradiation (40-50 Gy) and chemotherapy (800 mg/m2 5-FU and 20 mg/m2 cisplatin) 1.5 months prior to surgery; Group 3 (19 patients) treated with radiotherapy (60-70 Gy) (median interval 78.7 months; IQR 31.3 months) prior to surgery. From each of the 220 vessel specimens, 3 sections each were histomorphometrically investigated, both qualitatively and quantitatively. To evaluate these changes as a function of age, radiation dose and chemotherapy, a statistical analysis was performed using analysis of covariance and chi-square tests. In Group 3, qualitative changes (intima dehiscence, hyalinosis) were found in recipient arteries significantly more frequently (25%, P=0.009) than in Groups 1 and 2. For Group 3 recipient arteries, histomorphometry revealed a significant decrease in the ratio of media area/total vessel area (median 0.53, IQR 0.10) in comparison with Group 1 (P= 0.02) (median 0.60, IQR 0.29) and Group 2 (P=0.046) (median 0.59, IQR 0.10). No significant differences were found between the vessels of Groups 1 and 2 (P= 0.48). Age and chemotherapy did not appear to have a significant influence on vessel changes in this study.

Adult↗
PubMed1999

Improved discrimination of AD patients using beta-amyloid(1-42) and tau levels in CSF.

OBJECTIVE: To evaluate CSF levels of beta-amyloid(1-42) (Abeta42) alone and in combination with CSF tau for distinguishing AD from other conditions. METHODS: At 10 centers in Europe and the United States, 150 CSF samples from AD patients were analyzed and compared with 100 CSF samples from healthy volunteers or patients with disorders not associated with pathologic conditions of the brain (CON), 84 patients with other neurologic disorders (ND), and 79 patients with non-Alzheimer types of dementia (NAD). Sandwich ELISA techniques were used on site for measuring Abeta42 and tau. RESULTS: Median levels of Abeta42 in CSF were significantly lower in AD (487 pg/mL) than in CON (849 pg/mL; p = 0.001), ND (643 pg/mL; p = 0.001), and NAD (603 pg/mL; p = 0.001). Discrimination of AD from CON and ND was significantly improved by the combined assessment of Abeta42 and tau. At 85% sensitivity, specificity of the combined test was 86% (95% CI: 81% to 91%) compared with 55% (95% CI: 47% to 62%) for Abeta42 alone and 65% (95% CI: 58% to 72%) for tau. The combined test at 85% sensitivity was 58% (95% CI: 47% to 69%) specific for NAD. The APOE e4 gene load was negatively correlated with Abeta42 levels not only in AD but also in NAD. CONCLUSIONS: The combined measure of CSF Abeta42 and tau meets the requirements for clinical use in discriminating AD from normal aging and specific neurologic disorders.

Adult↗
PubMed1999

Sleep disorders and portal-systemic encephalopathy following transjugular intrahepatic portosystemic stent shunt in patients with liver cirrhosis. Relation to plasma tryptophan.

Neuropsychiatric symptoms due to any type of dysfunction and/or portal-systemic shunting are summarized as hepatic encephalopathy (HE). HE in the presence of liver cirrhosis and/or portal-systemic shunting has been termed portal-systemic encephalopathy (PSE). PSE is most frequent among the HE syndromes and is almost exclusively seen in patients with advanced cirrhosis and portal hypertension. Portal-systemic shunting either spontaneous due to portal hypertension, following surgical portocaval anastomosis, or subsequent to transjugular intrahepatic portosystemic stent-shunt (TIPSS) is regarded as the primary causative condition for PSE, not hepatic dysfunction per se. PSE may be considered as a disorder of multiple neurotransmitter systems among which derangements of the serotonergic system have been documented most consistently. Incipient PSE is frequently paralleled by the occurrence of sleep disorders, however, their relation to PSE remains unclear. We observed a transient increase of sleep disorders post-TIPSS, which were only in part correlated to other symptoms of PSE. Among the biochemical parameters studied only an association between arterial ammonia levels and sleep disorders became apparent, whereas no significant relation was observed for peripheral tryptophan.

Adult↗
PubMed1999

[Roentgenologic, endoscopic and ultrasound evaluation of the maxillary sinus after sinus lift with simultaneous endosseous implantation].

X-ray, ultrasound, and endoscopy were used in follow-up after sinus floor augmentation. In 23 out of 63 patients, healing was uneventful. Water's view revealed opacification of the maxillary sinus 1 week postoperatively in 40 patients, and opacification persisted in four patients. In these patients, endoscopy showed inflammatory reactions of the mucosa. Ultrasound proved to be a valuable tool in follow-up. Sinusitis occurred in three patients and was due to migration of bone chips in two of these. Out of 132 inserted implants, eight were lost during the healing period and three more during the loading period.

Alveolar Bone Loss↗
PubMed1999

The N-methyl-D-aspartate receptor channel blocker amantadine does not cause histopathological alterations in human brain tissue.

Low doses of N-methyl-D-aspartate (NMDA)-type glutamate receptor antagonists induce morphological alterations in neurons of the cingulate gyrus and retrosplenial cortex of the rat. Neuronal cell death may result at higher doses. These effects are a major concern with regard to the introduction of new NMDA receptor antagonists into clinical trials. Amantadine is an uncompetitive NMDA receptor antagonist, which has been in clinical use for many years. In the present study we have looked for possible morphological alterations like necrosis in postmortem human brain tissue of patients previously treated with amantadine. Formalin-fixed tissue samples were taken from the hippocampus, cingulate gyrus, and retrosplenial cortex of 8 patients on previous amantadine medication and of 11 controls. Histopathological examination of sections was performed blind. All brains except one revealed either nonspecific age-related or cerebrovascular changes or other neurodegenerative disorders including Alzheimer's, Parkinson's or Lewy body disease. In conclusion, histopathological examination of the hippocampus, retrosplenial cortex, and cingulate gyrus of human brain did not reveal changes suggested to be specific for previous amantadine treatment.

Aged↗