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Biomedical subjects

J Huber

Publications and source records attributed to J Huber.

317 records · Page 18Linked to original sources
PubMedDate not supplied

Menopause-associated differences in female fat patterning estimated by dual-energy X-ray absorptiometry.

The aim of the present study was to describe and quantify the typical changes in fat patterning from premenopause to postmenopause. The absolute and relative fat and lean body mass were estimated using dual-energy X-ray absorptiometry in 461 healthy non-obese females between the ages of 18 and 64 years (x = 43.2). Significant differences (p < 0.001) in absolute and relative fat mass, body weight and body mass index between pre-, peri- and postmenopausal females were observed. Postmenopausal women were significantly heavier (BMI, x = 26.8) than perimenopausal (BMI, x = 24.4) and younger and older premenopausal women (BMI, x = 22.8) and showed significantly higher fat percentages (fat% x = 38.1) in comparison to perimenopausal (x = 36.8) and premenopausal females (x = 31.4). Three indices, upper body composition index, lower body composition index and fat distribution index were calculated. Typical differences in fat distribution patterns between females of differential menopausal status were found. During the premenopausal phase a more gynoid type of fat distribution prevailed, during the postmenopausal phase a more android kind of fat distribution occurred predominantly. The fat distribution during the perimenopause can be interpreted as less gynoid than during the premenopause.

Absorptiometry, Photon↗
PubMedDate not supplied

Systematic strength training as a model of therapeutic intervention. A controlled trial in postmenopausal women with osteopenia.

Physical exercise is often recommended as a therapeutic tool to combat pre- and postmenopausal loss of bone density. However, the relationship between training dosage (intensity, duration, frequency) and the effect on bone density still is undergoing discussion. Furthermore, the exercise quantification programs are often described so inadequately that they are neither quantitatively nor qualitatively reproducible. The aim of this investigation was to determine whether a clearly defined training of muscle strength, under defined safety aspects, performed only twice weekly, can counteract bone density loss in women with postmenopausal osteopenia. Data from 16 women in the training group (age, 63.6 +/- 6.2 yr) and 15 women in the control group (age, 67.4 +/-9.7 yr), of comparable height and weight, were evaluated. Strength training was performed for 6 mo as continually adapted strength training, providing an intensity of about 70% of each test person's one repetition maximum. Bone mineral density of lumbar vertebrae 2 to 4 and the femoral neck was measured by dual-energy x-ray absorptiometry. Maximum performance in watts and parameters of hemodynamics were controlled with a bicycle ergometer test to maximal effort. In addition, metabolic data were assessed. In the lumbar spine and femoral neck, the training group showed no significant changes, whereas the control group demonstrated a significant loss of bone mineral density, especially in the femoral neck (P<0.05). The strength increase was highly significant in all exercised muscle groups, rising to about 70% above the pretraining status (P<0.001). Heart rate and blood pressure data indicated a slight economization, metabolism was not significantly influenced. Based on these findings, we conclude that continually adapted strength training is an effective, safe, reproducible, and adaptable method of therapeutic strength training, following only two exercise sessions per week.

Absorptiometry, Photon↗
PubMedDate not supplied

Fast wavelength scanning reflectance spectrophotometer for noninvasive determination of hemoglobin oxygenation in human skin.

Oxygen saturation of hemoglobin (HbSO2) in skin vessels may be determined with photometric methods. However, the optical complexity of the skin makes quantitative measurements difficult. A possible approach is the analysis of reflectance spectra using the two-flux theory of Kubelka and Munk. The final equation of this theory which describes the transformation between absorbed and reflected light has been approximated by a hyperbola. Based on this approximation we evaluated skin spectra obtained from the forearm of 23 healthy subjects with a fast scanning reflection photometer (Oxyscan) applying visible light (535-620 nm). The hyperbola was used in a multicomponent analysis in which the measured spectrum is recalculated using reference spectra of oxygenated and deoxygenated hemoglobin (gaussian least-square method). A crucial requirement for the evaluation is the subtraction of the individual skin spectrum, obtained by clearing a spot of skin of hemoglobin exerting external pressure. At rest HbSO2 was in the range between 42 and 89% (mean +/- SD: 72.9 +/- 12.2%). Pharmacological and thermal generation of hyperemia combined with respiration of pure oxygen raised the values to 86-100% (97.9 +/- 4.6%). This was in good agreement with capillary ex vivo analysis yielding 96-100% (98.7 +/- 0.4%). Under arterial occlusion HbSO2 fell below 30% (14.5 +/- 7.8%). Our method allows rapid determinations of absolute HbSO2 values in the skin. The evaluation error is estimated to be between 5% for oxygenated and 10% for deoxygenated values.

Arterial Occlusive Diseases↗
PubMedDate not supplied

[Effect of surface energy on wear characteristics of material combinations for the artificial hip joint].

One of the factors determining the wear of UHMWPE used as acetabular cup material is the lubricating properties of the head materials. In order to determine the lubricating properties, the wettability of Al2O3, ZrO2, CoCrMo and N-coated TiAl6V4 was established. Wettability is determined by the surface energy of the head material (solid-state material), which was measured via the contact angle of drops of fluid. As head material, appropriate rings from the Ring-on-Disc Test as per International Standard 6474 were used. The poorest wettability was associated with CoCrMo. The wettability of Al2O3 and ZrO2 was comparable. Worthy of note is the tendentially good wettability of N-coated TiAl6V4.

Biomechanical Phenomena↗
PubMedDate not supplied

The cellular substrate: a very important requirement for baculovirus in vitro replication.

We established more than 200 primary cell lines of Cydia pomonella (coding moth). 81 of them were selected and screened for replication of two baculoviruses (from two different subgroups): the Choristoneura murinana NPV and the Cydia pomonella GV. Although all these cell lines had been derived from the same insect species, they varied largely in their response to challenge with the NPV. Most of them showed CPE or produced different amounts of polyhedra. Interestingly, we also found a few cell lines that were permissive for GV replication. To our knowledge this is the first time that GV replication in cell lines has been obtained. Our results show that cell line properties are most important for baculovirus in vitro replication.

Animals↗
PubMedDate not supplied

Oncogenesis by mutations in anti-oncogenes: a view.

Oncogenesis is the result of accumulation of specific gene mutations. Two classes of specific cancer mutations are distinguished: namely those affecting anti-oncogenes and those in which oncogenes are involved. Anti-oncogenes are thought to regulate normal growth by encoding proteins that inhibit the expression of the oncogenes. This is in line with the observation that tumor cells are often homozygous for a defect in an anti-oncogene, as this will allow the expression of an oncogene. In this paper we attempt to calculate the number of anti-oncogenes involved in the genesis of a malignant tumour cell. These calculations were initially performed using a simplified model for oncogenesis and later applied to more complicated situations. These calculations indicate that usually four mutations in anti-oncogenes are required for oncogenesis in adults. This is in contradiction to the well-known 2-hit model of oncogenesis of Knudson which predicts about 10(9) times more de novo arising tumour cells than are observed in reality. Oncogenesis is only observed in proliferating cells. Cell proliferation and growth kinetics in various organs differ greatly. Therefore the time of oncogenesis and tumour manifestation also varies in the different organs. In organs that develop in early life (e.g. retina and neurons of the brain) mitotic activity ceases soon after birth. Consequently neural and retinal tumours emerge only early in life. In contrast, the main development of the female breast occurs after puberty, and the earliest breast tumours will become apparent in young adults. The four recessive mutations in anti-oncogenes required for oncogenesis imply that probably recessive mutations are involved in two loci. It is clear that an inherited mutation in an anti-oncogene at a particular locus causes different tumour types depending on the various organs in which the tumours arise. Comparison of (a) results of calculations about the number of malignant neuroendocrine tumour cells that arise in a pancreatic islet of a patient with inherited MEN1-syndrome with (b) the pathological anatomy of such a patient, suggests that a cell with two or three oncogenic mutations has a growth advantage over normal cells. This leads to cell proliferation in a premalignant lesion until the set of four oncogenic mutations is complete. The clinically premalignant lesions have a maximal mean diameter of about 0.4 cm when the first true malignant tumour cell develops, and the pathologist will probably note malignancy when the lesion has the size of 1-2 cm.(ABSTRACT TRUNCATED AT 400 WORDS)

Humans↗
PubMedDate not supplied

Hereditary cancer and its clinical implications: a view.

In hereditary cancers the responsible inherited cancer genes are defective (mutated) anti-oncogenes (tumour suppressor genes). This inherited mutation is present in all cells of the organism, and only leads to cancer if in a somatic cell a complete set of specific cancer mutations is accumulated. Since one defective anti-oncogene has been inherited, only three additional somatic cancer mutations are required, according to our previously published view (Anticancer Res 10:1990). The number of de novo arising tumour cells in such a person is thus multiplied by a factor equal to the reverse of the mutant frequency, that is about 10(4)-10(5). This can be observed e.g. in retinoblastoma. Mutations occur in proliferating cells only. Consequently cancer mutations also depend on cell proliferation. If an inherited cancer mutation predisposes to cancer formation in certain organs, then the cancer risk in these organs is enhanced by 10(4)-10(5) times. Tumours in these organs will appear simultaneously if the number of cells and the growth kinetics are similar. This is of course observed in paired organs, like the retina and the female breast. In cancer family syndromes different organs may be affected at the same time. Examples are type I and type II cancer family syndrome and multiple endocrine neoplasia type 1 2a, and 2b. The secondly diagnosed tumours are not caused by metastatic spread. Tumours in two organs will arise at difference times if the number of end cells per organ and the growth kinetics differ. In this case the second tumour is called a second primary malignancy and is not caused by metastatic spread. A good example are the second primary malignancies in hereditary retinoblastoma. The inherited defective anti-oncogene is a recessive gene. This defective inherited gene causes a 10(4)-10(5) fold increase of the normal tumour incidence. This means that nearly always one or more tumours will arise. Evidently, this pattern of inheritance has led to the erroneous conclusion that the genetic abnormality is dominant at the level of the chromosome. The 10(4)-10(5) times enhanced tumour incidence in hereditary cancer is helpful for the clinical recognition of hereditary cancer. That is, hereditary cancer can be recognized not only by family history, but also by early occurrence, the multifocal and bilateral localisation, its occurrence as cancer family syndrome or by second primary malignancies. It is thus recommended to screen patients and families with hereditary cancer for first and second primary tumours. Treatment of patients with hereditary tumours requires extra care to avoid additional cancer mutations.(ABSTRACT TRUNCATED AT 400 WORDS)

Genes, Dominant↗
PubMedDate not supplied

[Endocrine changes following progesterone substitution in early pregnancy].

250 mg hydroxy-progesteronecaproate was used for intramuscular administration in 25 patients, between 11 and 15 week's gestation, presenting either with a history of recurrent abortion or being admitted because of threatened abortion. Beta-HCG and progesterone concentrations were determined twice at intervals of 24 hours. Three women aborted without showing any increase in Beta-HCG levels nore in progesterone levels. In 20 patients Beta-HCG concentrations increased significantly after the medication, whereas only 5 patients showed a rise in progesterone levels. In 14 patients serum progesterone concentrations decreased making the use of progestational steroids in the management of threatened abortion questionable.

17 alpha-Hydroxyprogesterone Caproate↗
PubMedDate not supplied

[Atrial natriuretic peptide, antidiuretic hormone and aldosterone during delivery and the puerperium].

Plasma concentrations of ANP, Aldosteron and ADH were determined immediately ante- and post-partum and on the second day of puerperium in 36 healthy women, 12 primiparous and 24 multiparous. These parameters were also measured by RIA in umbilical cord plasma obtained at the time of delivery. The values were compared with an age-matched group of non pregnant women. The mean ANP-values before and after birth showed no significant difference but they were higher than in the non pregnant controls, and in umbilical cord plasma. The mean Aldosteron values during pregnancy and puerperium were significantly elevated against the non pregnant women, but they showed a marked decrease on the second day of puerperium. The mean Aldosteron levels in umbilical cord plasma were higher than all pregnant values. The mean ADH-levels before and after birth were also elevated against the non pregnant group, but on the second day of puerperium a significant decrease was established. The mean values of umbilical cord plasma were significantly elevated against all other maternal and non pregnant values.

Adolescent↗
PubMedDate not supplied

Abnormal expression of secretory component in term newborns with bowel perforation--a report of two cases.

Expression of secretory component (SC) in intestinal resection specimens from two term newborns with bowel perforation due to necrotizing enterocolitis (NEC) or and NEC-like syndrome was determined and compared with the SC immunoreactivity in a panel of intestinal tissues from fetuses at different ages of gestation. Expression of SC was absent in one patient, whereas in the other patient, SC immunoreactivity was observed in the basal cell part of colonic epithelium only. SC was normally expressed in a follow-up biopsy on one of these patients. In contrast, SC was present in the apical plasma membrane and brush border of colonic epithelium from 32 weeks of gestation onwards in fetuses without demonstrable intestinal disease. From these findings we conclude that the expression of SC was impaired in our patients, thus possibly playing a role in the development of the bowel perforation in these full-term newborns with an NEC-like syndrome or resulting from its pathogenesis.

Enterocolitis, Pseudomembranous↗