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Biomedical subjects

J Richter

Publications and source records attributed to J Richter.

At least 307 records · Page 17Linked to original sources
PubMed1989

Psychophysical assessment of sinusoidal whole-body vibration in z-axis between 0.6 and 5 Hz combined with different noise levels.

Nine healthy sitting males evaluated the intensity of vertical whole-body vibration (WBV) in z-axis at four frequencies (F1 = 0.63 Hz, F2 = 1.25 Hz, F3 = 2.5 Hz, F4 = 5 Hz) and two intensities (I1 = 1 ms-2 rms, I2 = 2 ms-2 rms) by cross-modality matching (CMM). The subjects were simultaneously exposed to low-frequency noise at two levels (L1 = 65 dBA, L2 = 86 dBA). L1 and L2 were context conditions which did not have to be evaluated by CMM. The results indicate a flat response between F2 and F3; the sensitivity increases towards F1. Different exponents of Stevens' power law for the frequencies of WBV contradict the frequency range tested to be a sensory continuum. L2 caused practically significantly stronger sensations of the WBV-intensity from F1 to F3 (I1) and at F2 (I2). No synergistic effect of noise and WBV was shown at F3I2. Weighting factors were calculated for all exposure conditions using Stevens' power law. The weighting of F2 and F3 contradicts that of the International Standard ISO 2631-1985 (E). The results enable recommendations for the frequency weighting of WBV between 0.63 and 1 Hz, as well as for the equivalence of noise and WBV with combined exposure.

Adult↗
PubMed1989

Social relationships reflected by depressive inpatients.

In a study of 100 inpatients suffering from depressive symptoms, the influence of cognitive characteristics (negative automatic thoughts and dysfunctional attitudes) and of the severity of depression on the emotional reflections of social relationships were investigated at admission, discharge and 3 months follow-up. The reflections of strained relation and rejection in the family or partnership were significantly determined by negative cognitive patterns and severity of depression. The prognostic aspects of the assessed psychological characteristics and the psychotherapeutic implications of the results are discussed.

Adolescent↗
PubMed1989

[International trends in the study of room air quality and conclusions for East Germany].

The international literature is analyzed in order to recognize recent developments in the field of investigations of indoor air quality. Special attention is paid to the papers of the 4th International Conference on Indoor Air Quality and Climate, held in Berlin (West) August 1987. It is noticed that a certain emphasis is put on the investigation of volatile organic compounds and of radon and their effects on human health. General conclusions are drawn for the research on these problems in the GDR.

Air Pollutants↗
PubMed1989

[The effect of a high-frequency electromagnetic field (2.45 GHz) on perceptual processes, psychological performance and well-being].

In a sample of 8 male subjects the effect of an ultra-highfrequency electromagnetic field (f = 2.45 GHz) with power densities of 1,000, 500 and 100 microW/cm2 was investigated. As parameters were used the perceptional threshold in a tachistoscopic perceptional test, the total time from the numbersearch-test and the sum of acute symptoms and complaints measured by a special questionnaire. At the highest field intensity on the one side increases of the total times and of the sum of complaints occurred. The differential threshold increased distinctly under 500 microW/cm2 exposure, whereas the total times and the sum of symptoms were not affected. At the lowest power density no differences between exposure and nonexposure conditions have been found. The intraindividual variability was considerable.

Adult↗
PubMed1989

Immunity and effects of the environment--an attempt at generalization.

The authors address themselves to the issues of functional capacity of the immune system and various factors exerting positive and negative effects on it. An attempt is made at graphic representation describing differences in the immune capacity of healthy and deficient organisms in normal living conditions and under challenge, thus forming the basis for a putative generalization of the addressed relationships.

Environment↗
PubMed1989

[Laboratory studies of vibration transmission in motor vehicle seats].

Operator seats (Models 050 and 500, Möve) were examined with vertical sinusoidal whole-body vibration (WBV) in the frequency range from 1 to 40 Hz (1.5 and 3.0 ms-2rms) and with simulated stochastic vibration of combines for the harvest of sugarcane. Six male subjects volunteered for the experiments. The WBV transmitted from the seat mounting base to the seat cushion and head were compared with data of a hard experimental seat. Interindividual differences cannot be explained by different body masses only. The iolation and main resonance of the two operator seats differed. Additional resonant peaks occurred above 6 Hz. They can cause unfavourable conditions at certain applications. The operator seats tested are probably suited for the reduction of WBV exposure on combines for the harvest of sugarcane.

Adult↗
PubMed1989

[Laboratory studies on the subjective evaluation of motor vehicle seats].

Operator seats (Models 050 and 500, Möve) were examined with vertical sinusoidal whole-body vibration (WBV) in the frequency range from 1 to 40 Hz (1.5 and 3.0 ms-2 rms) and with simulated stochastic vibration of combines for the harvest of sugarcane. Six male subjects volunteered for the experiments. The subjective assessments of operator seats by cross-modality matching, paired comparisons, and questionnaires were compared with data of a hard experimental seat. Transmitted WBV and subjective evaluation correlated partially only. Suggestions are derived for the improvement of the seats tested.

Adult↗
PubMed1989

[The microtexture of amnion and chorion connective tissue].

On microscopical, stereo-scan and TEM observations the microtexture of the connective tissue of amnion and chorion have been analysed. The "compact layer" of the amnion-connective tissue consists of single collagen fibrils, which are arranged felt-like in parallel layers. In the "fibroblast layer" the fibrils are mostly arranged in bundles, forming a network. Single fibrils and bundles of fibrils in both layers are arranged surface parallel. The superficial layer of the chorion's connective tissue is predominated by wave-like bundles of fibrils in parallel and latticed arrangements, which are consolidated by transversely and diagonally running fibres. In the inferior layer the fibres leave their formation, run diagonally in the direction of the trophoblast and interweave with each other to a mat of fibrils at the border to the trophoblast. The tensile strength of the amnion connective tissue is due to the felt-like fibril texture of the "compact-layer" and the special arrangement of surface-parallel collagen fibres and fibrils.

Amnion↗
PubMed1988

Isolated and combined effects of prolonged exposures to noise and whole-body vibration on hearing, vision and strain.

This study was carried out in order: (1) to examine the effects of isolated and combined prolonged exposures to noise and whole-body vibration on hearing, vision and subjectively experienced strain, and (2) to check the combined effects with repeated exposures. Six male subjects were exposed twice to noise (N) at 92 dBA, whole-body vibration (V) in the Z-axis at 4 Hz and 1.0 ms-2 rms, and noise and vibration (NV) for 90 min with each condition. Temporary threshold shifts of hearing (TTS) and their integrals (ITTS) were measured at 4, 6, 10, and 12 kHz. Visual acuity was examined by means of a very sensitive test. Cross-modality matching (CMM) of the handgrip force was used to judge the subjectively experienced strain. NV induced a clear tendency of higher TTS and ITTS than N, with several significant differences most pronounced at 10 kHz. With repeated exposures, the effect of NV decreased, while the reactions to N and V remained unchanged. The individual reactions to NV differed. The influence of the duration of exposures on vision depended on the condition; N caused time-dependent changes, whereas V did not. CMM-data increased with the duration of the exposure during V and NV. N was generally judged to be more straining than V; NV caused higher strain than V during the first 30 min of exposure only. Correlations between different effects suggest certain links between them. Additionally, less motivation--daily obtained by a questionnaire--often correlated with higher ITTS during N and NV. The results also illustrate the combined effects on the individual susceptibility, repetition of exposure, the kind of response, and, possibly, the actual psychic state.

Adolescent↗
PubMed1988

Hemofiltration and plasmapheresis in premature infants and newborns.

Extracorporal detoxication methods in newborns are most unavailable, contraindicated because of technical problems. Herein are reported the experiences with a blood pump unit that was miniaturized for hemodialysis, hemofiltration, and plasmapheresis in newborns. In three premature infants with acute renal failure of different etiology (two newborns with severe Rh-erythroblastosis, 1 premature infant with hypoproteinemia) 13 single-needle hemofiltrations and 6 single-needle plasmaphereses were performed with double head pump, special tube systems, and small modules. The age of the patients ranged from 1 to 14 days, body weight was between 800 and 2,800 g. Four umbilical veins and two femoral veins were used as vascular access. The ultrafiltration rate during the treatment averaged 0.3 ml/min in single-needle hemofiltration and the plasma filtrate flow rate 1.3 ml/min in single-needle plasmapheresis. All treatments were well tolerated. Four patients died due to complications unrelated to the treatment, two patients recovered. These preliminary results show that both hemofiltration and plasmapheresis may be carried out without major problems in premature infants and newborns.

Acute Kidney Injury↗
PubMed1988

Thymidylate synthase gene of herpesvirus ateles.

The putative thymidylate synthase (TS) gene of herpesvirus ateles, a T-lymphotropic tumor virus of New World primates, has a single large open reading frame encoding a polypeptide of 32.9 kilodaltons. The gene is transcribed into an unspliced 2.4-kilobase mRNA that is abundantly expressed late in virus replication. The AT-rich 5' untranslated leader sequence of TS mRNA in herpesvirus ateles-infected cells is remarkable in length (1,184 nucleotides), containing 29 minicistrons; this may indicate a role in translation regulation.

Amino Acid Sequence↗
PubMed1988

Detection of renal masses: sensitivities and specificities of excretory urography/linear tomography, US, and CT.

A prospective blinded study of 201 patients was performed to determine the relative sensitivities and specificities of excretory urography/linear tomography (EU/LT) and ultrasound (US) for the diagnosis of renal parenchymal masses. Computed tomography (CT) was used as a standard. EU/LT permitted detection of 10% of CT-confirmed masses (cystic or solid) less than 1 cm, 21% of lesions greater than or equal to 1 cm but less than 2 cm, 52% of lesions greater than or equal to 2 cm but less than 3 cm, and 85% of lesions 3 cm or more in diameter. US permitted detection of 26% of CT-confirmed lesions less than 1 cm, 60% of lesions greater than or equal to 1 cm but less than 2 cm, 82% of lesions greater than or equal to 2 cm but less than 3 cm, and 85% of lesions 3 cm or more in size. The results confirm the relative insensitivity of EU/LT for masses less than 3 cm in diameter and of US for masses less than 2 cm. Further, they suggest that CT may have a role not only in evaluation of cases in which the urographic or sonographic results are questionable or positive, but also in confirmation of apparently negative urographic findings when clinical suspicion of a lesion is high.

Carcinoma, Renal Cell↗
PubMed1988

[Not Available].

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General Surgery↗