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Biomedical subjects

H Weber

Publications and source records attributed to H Weber.

At least 433 records · Page 24Linked to original sources
PubMed1983

The clinical acceptance of dental nickel-chrome alloys.

Replacing gold alloys by non-precious ones could save more than 500 million DM per year in German dentistry. However, there are many technical and biological considerations which have to be resolved in evaluating the clinical suitability of non-precious metal alloys. Techniques (e.g. investing, casting, porcelain application) and materials, developed over decades for processing gold alloys, have to be modified in order to achieve complete, sound castings, showing accurate fit and good ceramic-metal bonding. During the 5 years of our clinical studies, no case of localized or generalized tissue reaction due to Ni-Cr alloys was found. The five patients known to suffer from nickel allergy did not show any reaction to Ni-Cr test plates. Although several Ni-Cr alloys are routinely and successfully used in our clinic for single crowns and small bridges as well as for appliances used in complete oral rehabilitation, it should not be assumed that all Ni-Cr based alloys commercially available are equally suitable. There are two main reasons for this: (1) The Ni-Cr alloys comprise a large group; individual alloys exhibit greatly varied composition, microstructure, physical properties and corrosion behaviour. (2) Standards (specifications) by which non-precious metal alloys could be tested, with special regard to their biocompatibility, are lacking. Empirically, some Ni-Cr alloys have turned out to be useful in prosthodontics but further progress will depend upon the development of suitable standards. These are needed urgently.

Chemical Phenomena↗
PubMed1983

[Combination of local anesthesia and intubation anesthesia in ophthalmic surgery - a gentle anesthetic technic for high risk patients].

Local analgesia has its definite place in ophthalmic surgery, but is restricted to short-term procedures. Major surgery involving longer periods of manipulation, especially of the retina and vitreous body, usually require general anaesthesia. These patients, predominantly elderly and of reduced general health, are at risk especially during the postoperative period. Regaining consciousness and protective reflexes quickly is essential in this group. To reduce the dosage of potent general anaesthetics in a pilot study a special risk group received a combination of retrobulbar local analgesia and light general anaesthesia. It was found that with optimal local blockade of pain conduction, general anaesthetics could be reduced as compared to a control group receiving general anaesthesia alone. The special advantage of this combined anaesthetic technique became evident during the postoperative period, since foreshortened recovery of consciousness, complete orientation as to time and space allowed referral to the ward at an early date. Particularly advantageous in these patients at risk was the prolongation of analgesia in the operated eye well into the postoperative period.

Adult↗
PubMed1983

High-effective aluminium free phosphate binder. In vitro and in vivo studies.

For the purpose of intestinal phosphate binding we have developed aluminium free natural polymers consisting of heteropolyuronic acid charged with different cations. The in vitro experiments showed an efficacy two to three times greater than Aludrox. During up to six months of clinical application no serious side effects have been detected, constipation ceased and serum phosphate was maintained in an acceptable range.

Humans↗
PubMed1983

[Emergency treatment of arrhythmias in neonates and infants].

Emergency treatment of cardiac arrhythmias was required in 41 newborn and infants aged two days to 9 months (mean 77 days) from July 1977 until September 1981. Heart defects were present in 27 (65.8%). Invasive electrophysiological studies were performed in all patients. The different types of arrhythmias were: bradyarrhythmias in 9 (21.9%): bradycardia to cardiac arrest (5), congenital complete AV-block (3), postoperative complete AV-block (1). Tachyarrhythmias in 32 patients (78.1%): reentry through accessory connections (21), congenital atrial flutter (6), ventricular flutter/fibrillation (3), and AV-nodal tachycardia (2). Overdrive atrial or ventricular stimulation with a consecutive series of 15-20 impulses of 5-10 Volts abolished arrhythmic attacks in 22 patients including 4 in whom prior digitalization had no effect. In two other patients overdrive pacing achieved sinus rhythm only after i.v. Propafenon. In 4 further patients 36.2 to 63.8 mg/m2 i.v. Propafenon and in 4 other patients DC synchronized cardioversion with 1 to 3 Wsec/kg restored a normal heart rate. The 3 patients with congenital complete heart block died, one despite permanent pacing. Oral Propafenon therapy with 300 mg/m2 die in three divided doses following emergency therapy of tachyarrhythmias was discontinued in patients without arrhythmias after 1 year on drug therapy. There was no relapse after a mean follow-up period of 1.9 years. Only patients with congestive heart failure due to cardiac defects needed additional digitalisation. Thus, in our experience antiarrhythmic drug therapy with Propafenon was more effective in this age group than digitalization.

Arrhythmias, Cardiac↗
PubMed1983

[Electroencephalogram in standardized mental stress: variable trends in the theta, alpha and beta band].

The results, gained in previous studies by means of computer-assisted interval analysis and amplitude analysis, of power spectra as well as of visuomanual pattern evaluation of the EEG during standardized mental load, were related to each other. Described are the significantly requirement-dependent trends of data in there three frequency bands. Under consideration of methodological rules (complementarity, non-reactive measuring, multivariate representation, balanced change-over design, multidimensional data analysis etc.) a characterization of the EEG functional test (graded cognitive strain, eyes opened) is given.

Adult↗
PubMed1983

[Periods and amplitude distribution parameters of the EEG in mental stress--on the concordance of mechanical and visuomanual methods of evaluation].

Mean frequency, % index and mean amplitudes in 3 frequency bands served as basis for a dynamic comparison of manual and computer assisted EEG analyses in healthy adults. In spite of inevitable methodical deviations it was possible to assume quite a good concordance for the significant data trends with but one exception. Among others the mean frequencies proved to be predicative variables in the EEG functional test with eyes opened. The satisfactory result provides arguments for a greater involvement of automated methods for quantitative description of the EEG activity in clinical practice.

Adult↗
PubMed1983

Pharmacokinetic studies following systemic and topical administration of [14C]bifonazole in man.

[14C]Bifonazole (1-[(4-Biphenylyl)-phenylmethyl]-1H-imidazole, Bay h 4502, Mycospor) was administered systemically (i.v.) and topically (dermally) in different formulations to a total of 17 volunteers. In the serum, the concentrations of total radioactivity and of the unchanged drug were determined by liquid scintillation counting techniques and by thin-layer densitometry, respectively. Urine and feces were collected and radioassayed. The extent of percutaneous absorption was calculated. In addition, distribution of the unchanged drug in the layers of the skin was studied radiometrically in three patients. After intravenous administration, bifonazole was eliminated from the serum largely in metabolized form. The half-lives of elimination of the radioactivity from the serum were approximately 7 and 42 h. Within 5 days 45% of the dose was excreted with the urine, and 39% with the feces. After topical application to healthy skin areas, under occlusive conditions, less than 1% of bifonazole was absorbed percutaneously from a 1% solution or cream, and the amount absorbed was excreted with the urine and the feces in approximately the same proportions as after i.v. administration. Following administration of the drug to inflamed skin, the proportion absorbed was 3 to 4% of the dose administered and thus higher than after application to normal skin. Studies on depth localization showed that the drug has a high capacity for skin penetration. Even in the lower layers of the epidermis, bifonazole was present in amounts several times as high as the minimum inhibitory concentrations for dermatophytes measured in vitro.

Administration, Topical↗
PubMed1983

Lumbar disc herniation. A controlled, prospective study with ten years of observation.

Two hundred eighty patients with herniated lumbar discs, verified by radiculography, were divided into three groups. One group, which mainly will be dealt with in this paper, consisted of 126 patients with uncertain indication for surgical treatment, who had their therapy decided by randomization which permitted comparison between the results of surgical and conservative treatment. Another group comprising 67 patients had symptoms and signs that beyond doubt, required surgical therapy. The third group of 87 patients was treated conservatively because there was no indication for operative intervention. Follow-up examinations in the first group were performed after one, four, and ten years. The controlled trial showed a statistically significant better result in the surgically treated group at the one-year follow-up examination. After four years the operated patients still showed better results, but the difference was no longer statistically significant. Only minor changes took place during the last six years of observation.

Adult↗
PubMed1983

[Metabolic changes in a 3-week treatment with a low calorie protein-carbohydrate diet in massively obese adolescents].

8 massively obese adolescents (2 girls, 6 boys, mean age 12.6 +/- 2.1 years, mean overweight 74 +/- 14%) were treated for 3 weeks with a very low calory diet (VLCD), containing 240 kcal, 33 g protein, 25.5 g carbohydrates and 0.7 g fat. Mean weight loss after 3 weeks was 9.47 +/- 2.8 kg. The mean loss of total nitrogen was 232.4 +/- 73.2 g. Great individual variations in regard to the amounts of nitrogen loss occurred. The mean nitrogen loss over the period of 21 days was 113.3 +/- 71.2 g. Three patients reached positive nitrogen balance in the third week. No pathological changes could be shown for serum electrolytes and enzymes as well as for glucose, urea and creatinine. At the end of the first week serum uric acid values were elevated, but reached normal values at the end of the diet period. 3 patients were treated with Allopurinol 200 mg for 7 to 14 days. Serum protein concentrations fell significantly from 7.64 +/- 0.3 to 7.0 +/- 0.2 g/dl, whereas serum albumin concentrations remained constant. Cholesterol and LDL-cholesterol fell significantly (p less than 0.001) to "supranormal" values, HDL-cholesterol and triglycerides remained almost constant. 24-h-ECG investigations before, during and after the diet did not reveal any pathological findings.

Adolescent↗
PubMed1982

RNA splicing is required to make the messenger RNA for a variant surface antigen in trypanosomes.

The expression of the gene for variant surface glycoprotein (VSG) 118 in Trypanosoma brucei is activated by transposing a DNA segment containing the gene and 1-2 kb in front of it to an expression site elsewhere in the genome. By S1 nuclease protection and RNA blotting experiments we show here the presence of several minor transcripts in trypanosomes synthesizing VSG 118, one of which covers the entire transposed segment. Comparison of the sequence of the 5' terminal segment of VSG 118 messenger RNA (mRNA), determined by primed reverse transcription, and the corresponding region of the 118 VSG gene, shows that the 5' terminal 34 nucleotides of the mRNA are not encoded in the 118 VSG gene contiguous with the remainder of the mRNA. We conclude that synthesis of a VSG mRNA involves splicing of a much longer primary transcript, which may start outside the transposed segment.

Animals↗
PubMed1982

Structure elucidation of mammalian TCDD-metabolites.

Thin layer and gas chromatographic examination of the bile of dogs which were given tritium-labelled TCDD revealed the presence of several polar biotransformation products. The structure of 5 phenolic metabolites was elucidated by combined gas chromatography-mass spectrometry. A metabolic breakdown scheme for TCDD in the dog is proposed.

Animals↗
PubMed1982

Tachyarrhythmic syncopes in children with structurally normal hearts with and without QT-prolongation in the electrocardiogram.

Forty children with presumed ventricular tachyarrhythmic syncopes in the absence of structural heart disease were studied. Twenty-nine patients, one of whom was deaf, had a prolonged QT-interval in the resting electrocardiogram (Group 1); eleven patients had a normal QT-interval (Group 2). The median QTc-interval vas 0.51 s in Group 1 and 0.40 s in Group 2. Familial occurrence suggesting autosomal dominant inheritance was found in 21 of 28 normally hearing patients in Group 1 and in 2 of 11 patients in Group 2. Syncopes were definitely stress-induced in 22 patients in Group 1 and in all 11 patients in Group 2. Of 23 patients in Group 1 in whom an electrocardiogram was obtained during physical exercise, only one showed severe ventricular dysrhythmia. In contrast, all eleven patients in Group 2 developed severe ventricular dysrhythmia with exercise. Treatment with beta-blocking medication prevented further syncopes in 15 of 19 patients with several previous attacks in Group 1 and in 3 of 5 patients of Group 2. Four of the 29 patients in Group 1 died suddenly and one more remained apallic after an attack. Of the 11 patients in Group 2, four died suddenly and one retains severe cerebral damage after resuscitation from ventricular fibrillation. We conclude that, besides the group of patients with the long QT-syndrome, there may be a distinct group of patients with a consistently normal QT-interval and severe ventricular dysrhythmia with exercise. Patients of both groups are threatened by sudden death and are improved by treatment with beta-blocking medication.

Adolescent↗