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Biomedical subjects

H Seidel

Publications and source records attributed to H Seidel.

At least 127 records · Page 7Linked to original sources
PubMed1978

The autoregressive time series modelling of stabilograms.

Power spectral density analysis of frontal and sagittal stabilograms in young male subjects with a normal vestibular function indicates the fitting of parametric time series models to stabilograms. Subjects were standing on a force platform under three different standing conditions. Stabilograms lasting for 2 minutes were processed by means of a TPAi computer with the CAMAC system. Following digital high-pass filtering, correlation functions and power spectral density distributions were estimated. Linear autoregressive models of increasing order up to 30 were fitted to stabilograms on the basis of the autocorrelation functions by means of a recursive scheme. The goodness of fit of the autoregressive models was significantly different in the standing conditions, planes and subjects. The orders of models for frontal stabilograms were higher than for sagittal ones, whereas the residual variances were lower than for sagittal stabilograms. We arrived at the conclusion that autoregressive modelling is a suitable approach for obtaining reliable spectral estimates and for characterizing the control system of body sway.

Humans↗
PubMed1978

On the quantitative characterization of human body sway in experiments with long-term performance.

Two different conditions of standing were examined in young male subjects with an intact vestibular system by means of stabilography. Low-frequency sways were eliminated by means of a digital high-pass filter. The parameters of the histograms of amplitudes, the autocorrelation functions, and the power-spectral density were estimated. The quantitative parameters of the stabilograms are compared for the two standing positions, both for the frontal and sagittal planes. Quotients of estimates of variance components calculated on the basis of analysis of variance are stated as measures of reliability for the parameters of histograms of amplitudes and power-spectral density in defined frequency bands. The reliability of the standard deviations of amplitudes was much better than the reliability of skewness and excess. The reliability of spectral density differed for frequency ranges investigated. Generally, the quotients of estimates of variance components were higher for the spectral density in the frequency bands of sagittal stabilograms than in those of frontal ones. Performance significantly affected several parameters of histograms and the distributions of power-spectral density. Standard deviation of amplitudes and power-spectral density proved to be suitable for the quantitative characterization of stabilograms.

Behavior↗
PubMed1977

[Intraoperative temperature measurements at the acrylic bone/cement interface in total hip endoprosthetic (TEP) implantations (author's transl)].

Temperature measurements are reported effected by aid of thermocouples enclosed in tubules in TEP-implantations of the hip. Two techniques were employed: the first using as acrylic bone cement Palacos or Sulfix-6 without concomitant cooling, the second Palacos after precooling of the femur with crushed ice/water mixtures. The first method yielded, at the acrylic bone cement/bone interface, temperatures above the coagulation point of the protein (56 degrees C). The novel technique of implantation is described, i.e. the cooling of the bone with ice-water prior to the cement implantation. This technique provides a means of restricting the average temperature at the aforesaid interface to 45 degrees C.

Bone Cements↗
PubMed1977

[Additional information regarding periarticular ossifications after total hip replacement (author's transl)].

Residual monomer originating from acrylic bone cement is not the origin of periarticular calcifications after hip joint replacement. This has been demonstrated by gaschromatografic detection of monomeric methylmethacrylate in the liquid of the joint space. Up to 200 microng/ml monomeric MMA could be demonstrated in the first days after the operation only. The concentration of residual monomeric MMA in the bone cement is 1% to 4%. It is deminished time dependently by diffusion of the molecule in the surrounding tissue. All determined concentrations of monomeric MMA in the joint liquid are below the toxic range for tissue demage.

Calcinosis↗
PubMed1977

[Geriatric aspects in operative treatment of intertrochanteric fractures (author's transl)].

On the basis of published data and of 702 osteosyntheses carried out using the Pohl sliding hip screw, the authors come to the conclusion that the mortality rate in geriatric patients is not correlated to the method of osteosynthesis used. Of utmost importance are immediate operation and early mobilisation. The osteosynthesis of intertrochanteric fractures in geriatric patients must facilitate early loading of the fracture site. This paper compares intramedullary nails, pertrochanteric blade plates, Y-nails and sliding hip screws, and contrasts these with the authors' own experience with the Pohl sliding hip screw.

Age Factors↗
PubMed1977

[Spectrum analysis of stabilograms with special reference to changes following whole body vibration].

The location of the body's gravicenter in the horizontal plane was measured by means of a force platform. The 4 male subjects stood upright with eyes closed. Power-density spectra of the frontal and sagittal stabilograms were estimated. Repeated investigations made it possible to assess intraindividual variability and to evaluate significant interindividual differences. The power spectral density was not altered by a controlled sitting posture observed for 30 min. Low-frequency whole-body vibration with an exposure time of 30 min and a permissible level according to the "fatigue decreased proficiency boundary" (International Standard ISO 2631) induced a significant increase of the power spectral density below 0.25 Hz and a decrease above this frequency. The results indicate that the power density spectral analysis of stabilograms is a suitable method for evaluating a biological effect of vibration.

Humans↗
PubMed1977

[Pharmacokinetics of methylmethacrylate monomer of bone cements: method for qualitative and quantitative monomer determination in respiratory air].

The methylmethacrylate-monomer deported into circulation from bone cement implantation during endoprothetic operation is subject to unaltered exhalation. Qualitative evidence of monomer excretion in the exhaled air is established in animal experiment. The quantitative determination of monomer in the exhaled air in man undergoing hip-joint replacement are stated and the method is demonstrated. Pharmacocinetically exhalation has priority over metabolisation.

Acetabulum↗
PubMed1976

The role of new health practitioners in a prepaid group practice: changes in the distribution of ambulatory care between physician and nonphysician providers of care.

Changes in the distribution of ambulatory care between physicians and new health practitioners (NHP) are examined in the pediatric and adult medicine departments of a prepaid group practice program. The study covers a three-year period during which NHP were extensively introduced to provide a broad range of ambulatory care. The source of data is a routine data information system that utilizes an encounter form to capture a minimal data set on every patient visit, including the provider's statement of diagnosis. Based on these data, changes in staffing are related to changes in workload and content of practice of both physicians and NHP.

Adolescent↗
PubMed1976

[Gluconeogenetic capacity of suckling piglets and young pigs].

No marked gluconeogenetic performance was recordable from nursed piglets aged, between one and five days, in response to ACTH nor glucocorticosteroid application. Store pigs, aged twelve weeks, however, exhibited glucose rises of 34 per cent one hour after injection or 55 per cent three hours from ACTH application. The point was made, in an attempt to elucidate the above findings, that in newborn piglets, few days after birth, the gluconeogenetic capacity is insufficient because of functional immaturity of the liver. The behaviours of several metabolites in the liver and muscles of store pigs were examined under differentiated model conditions to check up and verify that view.

Adrenocorticotropic Hormone↗
PubMed1976

[A contribution to the relationship between electric systole and hypocalcemia in cattle].

Strong correlations between electric systole (QT time) and calcium-serum concentration can be statistically secured. In this context, all-transistor direct-printing electrocardiographs were used for indirect determination of calcium concentrations with the view to assessing QT time. The approach is described with reference to the need for safe and independent diagnosis of hypocalcaemic hysteroparalysis in concomitance with parturition against the background of industrialised cattle farming.

Animal Husbandry↗
PubMed1976

[Behavior of various metabolites of carbohydrate metabolism in the liver of young pigs following inhibition of C-11 hydroxylase and adrenalectomy].

The effects of glucocorticoid depression by C-11 hydroxylase inhibition and total adrenalectomy upon certain metabolites of the plasma, liver, and muscles that are related to gluconeogenesis were studied on ten store pigs. Metopiron caused decline of glucose and pyruvate concentrations in plasma and drop of liver glycogen. Total adrenalectomy caused changes of the same kind but much stronger in the agonal phase, yet without rendering the animals hypoglycaemic. Muscular glycogen dropped to one third of the normal. The results are discussed with reference to earlier studies into store pig.

Adrenalectomy↗