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Biomedical subjects

H Wagner

Publications and source records attributed to H Wagner.

At least 1,117 records · Page 62Linked to original sources
PubMedDate not supplied

Retrovirus genomes methylated by mammalian but not bacterial methylase are non-infectious.

The biological importance of DNA methylation for gene expression in eukaryotes is becoming increasingly evident, and a direct role of methylation in gene expression has been suggested by an analysis of the infectivity of integrated retroviral genomes in a transfection assay. These studies, however, did not address whether specific methylatable residues are involved in gene regulation. Methylation by sequence-specific bacterial DNA methylases has been shown to suppress the expression of some genes, but not others. To investigate the effect of methylation on gene expression without having to rely on sequence-specific methylases, a rat liver enzyme was used to methylate in vitro all C-G dinucleotides of a proviral genomic clone. This treatment reduced the biological activity of Moloney murine leukaemia virus (M-MuLV) proviral DNA by more than three orders of magnitude, whereas complete methylation of 35 HpaII sites in the same DNA had only a marginal effect. The rat methylase-induced inactivation was reversible, as treatment of recipient cells with 5-azacytidine rendered the non-infectious viral genomes biologically active. This suggests that methylation in other C-G dinucleotides than those detectable with restriction enzymes can be crucial for gene expression.

Animals↗
PubMedDate not supplied

[Femur revision prosthesis].

Aseptic loosening of total hip prostheses leads to increasing bone resorption. The extensive bone loss often does not allow a reliable stem implantation in the former prosthetic bed. An uncemented femoral revision prosthesis is presented which bridges the damaged bone and is firmly anchored in the diaphysis. Without bone-grafting postoperatively a vigorous bone regeneration begins at the former bone defects.

Bone Regeneration↗
PubMedDate not supplied

Comparison of the TEMPO+ ear-level speech processor and the cis pro+ body-worn processor in adult MED-EL cochlear implant users.

A study was conducted to compare the new MED-EL TEMPO+ ear-level speech processor with the CIS PRO+ body-worn processor in the COMBI 40/COMBI 40+ implant system. Speech tests were performed in 46 experienced subjects in two test sessions approximately 4 weeks apart. Subjects were switched over from the CIS PRO+ to the TEMPO+ in the first session and used only the TEMPO+ in the time between the two sessions. Speech tests included monosyllabic word tests and sentence tests via the telephone. An adaptive noise method was used to adjust each subject's scores to approximately 50%. Additionally, subjects had to complete a questionnaire based on their 4 weeks of experience with the TEMPO+. The speech test results showed a statistically significant improvement in the monosyllabic word scores with the TEMPO+. In addition, in the second session, subjects showed a significant improvement when using the telephone with the TEMPO+, indicating some learning in this task. In the questionnaire, the vast majority of subjects found that the TEMPO+ allows equal or better speech understanding and rated the sound quality of the TEMPO+ higher. All these objective and subjective results indicate the superiority of the TEMPO+ and are mainly attributed to a new coding strategy called CIS+ and its implementation in the TEMPO+. In other words, based on the results of this study, it appears that after switching over from the CIS PRO+ to the TEMPO+, subjects are able to maintain or even improve their own speech understanding capability.

Adult↗
PubMedDate not supplied

Potential anticancer agents, XI. X-ray structure determination of acantholide.

The X-ray structure of acantholide, a melampolide sesquiterpene lactone from Acanthospermum glabratum (DC.) Willd. was determined by the aid of direct methods. The compound was cytotoxic but displayed no antitumor activity. Evaluation of the X-ray and NMR data indicated that the same conformation exists in the solid state as in solution.

Antineoplastic Agents, Phytogenic↗
PubMedDate not supplied

Electrocochleography (ECochG) and brain stem evoked response recordings (BSER) in the diagnosis of acoustic neuromas.

Evaluation of the auditory evoked responses has hitherto been the most important otoneurological method for early diagnosis of acoustic neuromas. ECochG enables to recognize serious damage to the first neurone. Criteria are: increased latency of the action potential (N1) and a low amplitude of the action potential relative to a high amplitude of the microphonic potential. BSER is a more sensitive indicator for functional deficiency in the first neurone, especially by evaluating interaural differences of the interpeak intervals (IPI) I-V and I-III. Problems arising when wave I cannot be clearly detected can be overcome by combining ECochG and BSER and evaluating the latency N1-V or perhaps in a better way by applying derivation of BSER between promontory and vertex. In 24 of 25 patients with indistinctly defined wave I in the standard recording, evaluation was possible in promontory BSER.

Audiometry, Evoked Response↗
PubMedDate not supplied

Frequency-specific brainstem responses to bone-conducted tone pulses masked by notched noise.

As in the case of auditory brainstem responses (ABRs) to air-conducted stimuli, recording of frequency-specific ABRs to bone-conducted stimuli needs adequate masking of those parts of the basilar membrane that are not to contribute to the ABR. The present study shows that tone-pulse stimulation with notched noise-masking can be realized via a bone vibrator after its frequency response has been flattened. The latency-intensity curves for 4, 2, 1, and 0.5 kHz run approximately parallel, indicating the ABR to be indeed frequency-specific. As adequate air-conducted masking of the nontest ear can produce cross-masking, the use of an insert earphone is proposed. Because of its higher interaural attenuation, a higher masking level can be applied to the nontest ear.

Bone Conduction↗
PubMedDate not supplied

Surface replacement arthroplasty of the hip.

The principle of hip joint resurfacing is replacement of diseased joint surfaces and simultaneous restoration of the normal anatomy and biomechanical function to the maximal degree possible. This concept offers several theoretical advantages over conventional total hip joint replacement and the clinical results in this series of 426 cases appears to confirm the value of both the method and the concept. Successful joint resurfacing surgery with attention to detail. Most problems can be anticipated and handled appropriately. Complications are few. The operation should only be done in cases of severe hip disability, when the patient's level of suffering demands operative intervention and when the only reasonable alternatives are fusion, total joint replacement or head and neck resection. It is an operation designed and recommended as an "in-between" procedure to gain time against the progressive disease. Resurfacing should not be performed if conservative measures or classic hip osteotomies offer significant benefit. The principal advantages of this procedure relate directly to the prosthetic design. Only the joint surfaces are removed during surgery, most of the normal bone is preserved, the medullary canal is not opened, and the implants utilized are of small volume. As a result the risk of infection is low compared to other implant arthroplasty techniques and clinical statistics confirm this anticipated advantage. The operation is designed to interfere minimally with the normal joint mechanics so it is also anticipated that prosthesis longevity will be greater than when rigid stem prostheses are placed in elastic bone. As yet follow-up is too short to make valid judgments on this point. The technique is applicable to younger patients, however, because if it should, in time, fail and other surgical treatment becomes necessary the original alternatives of total hip replacement, arthrodesis, or head and neck resection remain available. Relief of pain is predictable and almost all patients have experienced significant improvement in function. The procedure has a broader indication in cases of prior bone or joint infection and is definitely a preferable procedure in young individuals with severe hip disability.

Acetabulum↗
PubMedDate not supplied

[The effects of methodical factors on the microphonic potential in the guinea pig cochlea with perfusion of perilymph].

The decreas in microphonic potentials detected from the round window (RMP) is negligible only if the bores are located very close to the round window, whereas it will increase with increasing distance from it. Only at pressures of more than +/- 30 cm water column, in rare cases even below that, will a sharp decrease in the RMP occur, possibly because of a lesion of either the oval or the round windown membrane. At a perfusion pressure above +5.6 cm water column, the perfusion liquid will enter the cerebrospinal fluid space. At a lower pressure the perfusion liquid is diluted by cerebrospinal fluid via the cochlear aqueduct. The perfusion speed of 1 to 50 mul/min has no effect on the function of the organ of Corti.

Action Potentials↗
PubMedDate not supplied

[The ERA characteristics in normal-hearing persons].

The ERA characteristics (amplitudes and latencies) were measured in normal-hearing adults (20 to 25 years of age) at frequencies of 500 Hz, 1000 Hz and 4 000 Hz. Two other age groups (30 to 50 and 55 to 70 years of age) were measured only at 1 000 Hz. Contrary to other authors, the linear scale was chosen to represent the amplitudes. In calculating the variances of the amplitudes it turned out that the intra-individual variance is significantly below the inter-individual variance. Expressed in per cent as a variational coefficient, both decrease with increasing stimulus intensity. Contrary to the behaviour of the amplitudes, no significant difference between the intra- and inter-individual variational coefficient of the latencies could be found. The same is valid for the variational coefficients of the N1 and P2 latencies. As a function of the stimulus strength, the variational coefficient passes through a minimum at medium stimulus intensity. Within the investigated range of 20 to 70 years of age, no significant differences of amplitudes and latencies between the age groups could be found.

Acoustic Stimulation↗
PubMedDate not supplied

Intracardiac repair of isolated ventricular septal defects below two years of age.

Experience with closure of ventricular septal defect in 32 patients under two years is presented. Indications for correction were: (a) intractable heart failure; (b) persistence of progression of pulmonary artery hypertension; (c) failure of pulmonary artery banding; (d) elective closure after banding. In all but one case, the correction was done under the surface induced deep hypothermia with limited cardiopulmonary bypass and total circulatory arrest. Mortality and morbidity of the pulmonary artery banding procedure and of early closure discussed. For the corrective procedure the mortality was 3%. It is emphasized that whenever clinical or hemodynamic data support persistence or progression of pulmonary artery hypertension, corrective repair should be performed without delay. It is further suggested that pulmonary artery banding should be restricted to patients with ventricular septal defect and associated coarctation of the aorta and to patients with multiple muscular ventricular septal defects.

Child, Preschool↗
PubMedDate not supplied

[Thyroid gland disorders in elderly psychiatric patients].

With 200 admissions of 192 patients to the psychogeriatric acute ward of the Zwiefalten State Mental Hospital serial measurements of serum concentrations of basal TSH and, if necessary, of total T3 and total T4 were carried out with the TRH tests performed. Basal TSH was decreased in 16% of patients and in 2% it was increased. Only three patients had manifest hyperthyroidism and one patient had marginal hypothyroidism. Regardless of their psychiatric diagnosis, patients with manifest hyperthyroidism showed psychomotor agitation, whereas those with latent and marginal hypothyroidism suffered from lack of impulse. These symptoms improved after treatment with carbimazol or levothyroxine, respectively, and psychotropic drugs. Therefore a thyroid screening should be performed on psychogeriatric patients regardless, including, when possible, repeat measurement of basal TSH and, if necessary, the test battery should include total T3 and total T4.

Aged↗
PubMedDate not supplied

The Berlin cochlear implant--surgical concept.

The extent of channel interactions using monopolar extrascalar stimulation probably limits the number of independently acting electrodes of a cochlear implant to three. Comparison of psychoacoustic and histopathological findings led to the conclusion that stimulation of the neurons in the upper basal and the second coil is of greatest benefit to the patient. By using a middle fossa approach, access to the upper basal coil and the second coil is possible without destruction of middle ear structures. The danger of infection is probably reduced. Using an additional external round-window electrode, a device providing three different stimulating electrodes can be applied.

Cochlea↗
PubMedDate not supplied

[Gold treatment of rheumatoid arthritis].

In basic therapy of Rheumatoid Arthritis gold is preferred. Continued as well as discontinued therapy is used. The effect of gold is of complex nature. Gold is localized in cells of the RES and mesenchyme main in the inflammatory area. The passing acceleration of mesenchyme metabolism possibly shortens the duration of the inflammatory process. Gold further shows effects on cellular and subcellular membranes, on collagen, ACTH-production and on immune reactions. Patients with high activity and slow progression of their disease are especially suitable for chrysotherapy. Low maintenance of gold levels is effective and inhibits toxic-allergical reactions may be in a sort of desensitisation.

Arthritis, Rheumatoid↗