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Biomedical subjects

M Neff

Publications and source records attributed to M Neff.

At least 19 recordsLinked to original sources
PubMed1997

Can the fast bone loss in osteoporotic and osteopenic patients be stopped with active vitamin D metabolites?

The aim of this study was to evaluate whether fast trabecular bone loss in osteoporotic and osteopenic patients can effectively be treated with active vitamin D metabolites. Thirty-one osteoporotic and osteopenic patients were monitored between 4 and 22 months before and between 8 and 18 months during the treatment. Fast bone losers were designated as osteoporotic or osteopenic patients with a loss of trabecular bone density in the radius of 3% or more calculated for 1 year. For this differentiation, the high precise peripheral quantitative computed tomography system (DENSISCAN 1000) was used (reproducibility 0.3% in mixed collectives). The pretreatment loss and the "gain" under treatment with active vitamin D metabolites was calculated for 1 year. The treatment consisted of either 0.5 micro;g calcitriol daily or 1 micro;g of alfacalcidol daily. Before treatment, the trabecular bone loss in the radius/year was -6.6 +/- 0.5% (mean +/- SEM). After treatment with vitamin D metabolites, the trabecular bone gain in the radius/year was 0.01 +/- 0.6% (mean +/- SEM). The difference was highly significant (P < 0.001). In contrast to this, the loss of cortical bone density before treatment was -1.8 +/- 0.3% (mean +/- SEM) and the reduced loss after treatment -0.2 +/- 0.4% (mean +/- SEM), both values calculated for 1 year. This difference was less significant (P < 0. 05). This study shows that the treatment with active vitamin D metabolites is very effective in slowing fast trabecular bone loss in osteoporotic and osteopenic patients.

Aged↗
PubMed1996

From seed germination to flowering, light controls plant development via the pigment phytochrome.

Plant growth and development are regulated by interactions between the environment and endogenous developmental programs. Of the various environmental factors controlling plant development, light plays an especially important role, in photosynthesis, in seasonal and diurnal time sensing, and as a cue for altering developmental pattern. Recently, several laboratories have devised a variety of genetic screens using Arabidopsis thaliana to dissect the signal transduction pathways of the various photoreceptor systems. Genetic analysis demonstrates that light responses are not simply endpoints of linear signal transduction pathways but are the result of the integration of information from a variety of photoreceptors through a complex network of interacting signaling components. These signaling components include the red/far-red light receptors, phytochromes, at least one blue light receptor, and negative regulatory genes (DET, COP, and FUS) that act downstream from the photoreceptors in the nucleus. In addition, a steroid hormone, brassinolide, also plays a role in light-regulated development and gene expression in Arabidopsis. These molecular and genetic data are allowing us to construct models of the mechanisms by which light controls development and gene expression in Arabidopsis. In the future, this knowledge can be used as a framework for understanding how all land plants respond to changes in their environment.

Germination↗
PubMed1995

[Prevention of postmenopausal osteoporosis: how effective is transdermal hormone substitution? (Continuous estradiol plus sequential oral norethisterone acetate)].

QUESTION: Can osteoporosis and cardiovascular risk be effectively and simultaneously prevented with transdermal estradiol replacement therapy (in combination with norethisterone acetate 1 mg per day, oral, cyclically for 12 days monthly)? METHODS: A selected, representative group of healthy women with an average age of 52 years, with confirmed natural menopause for 1 to 4 years, randomly allocated to a treatment-group with hormone replacement (n = 42) and a control-group (n = 70), with homogeneous main parameters in the two groups, can be compared, without distortion of the findings, during the period of the two-year intervention study: the purely trabecular bone mass in the distal radius was specifically measured, prospectively, with the highly accurate, three-dimensional, peripheral quantitative computed tomography (thin-und multi-layer technology; Densiscan 1000) and the serum lipid, lipoprotein and apolipoprotein levels were measured (at the end of the gestagen cycle) in the morning fasting state. RESULTS: One-third of the persons of the control-group showed an annual loss of trabecular bone mass of more than 3.5%. These fast-losers, who on the basis of the annual bone-destruction rates are to be classified in the upper tertiles of the two groups, suffered a loss of trabecular bone of 4.2 +/- 0.4% (mean +/- SEM) in the treatment-group, compared with 7.3 +/- 1.0% in the control-group in the first year; in the second year no loss of trabecular bone was observed in the treatment-group, while in the control-group the high rate of trabecular-bone destruction continued unchanged. The slow-losers (belonging to the middle and lower tertiles according to the bone loss rates) showed equally little change in their trabecular bone mass after the menopause, which can be described as physiological, with mean yearly values between -1.1 and +0.4%, both in the treatment-group and in the control-group. Under the transdermal hormone replacement therapy only the triglyceride and total cholesterol levels fell in comparison with the control-group, but without any significant changes in the atherogenic index, either in regard to the LDL/HDL or apolipoproteins B/A-I ratios. CONCLUSIONS: To be able to make valid statements it is necessary to study the effectiveness of a measure or of a preparation for the prevention of osteoporosis in fast-losers, who are to be randomized to the respective study-groups and whose status has been confirmed by tests. Transdermal hormone replacement therapy--low estradiol dose in combination with NETA--stops the pathologically increased loss of trabecular bone only in the second year of the treatment; the antiatherogenic effect, however, is not confirmed. Only an individually adjusted therapy based on test results, with follow-up controls, can constitute an efficient, ethically justifiable postmenopausal prophylaxis of both osteoporosis and coronary heart disease.

Administration, Cutaneous↗
PubMed1995

[Osteoporosis prevention initiated with peripheral quantitative computerized tomography. Thin-layer and multi-layer technique].

In a representative, randomized control group of 70 healthy confirmed postmenopausal women (natural menopause for one to four years) with an average age of 52 years, it was possible to carry out a prospective study over a period of two years, during which the bone mass was investigated regularly by means of peripheral quantitative computed tomography (pQCT, Densiscan type, thin- and multi-layer technology). The distal, purely trabecular and purely compact bone mass of the radius and tibia are measured separately. The epiphyseal trabecular bone masses of the radius and tibia (262 +/- 8 mg/cm3 and 252 +/- 8 mg/cm3, respectively) are initially homogeneous, but over time they show different rates of yearly loss of bone mass: 3.0 +/- 0.4%, compared with 1.5 +/- 0.3% (means +/- SEM). Based on the bimodal frequency distribution of the annual loss rates in the core trabecular volume of the distal radius, fast losers lose more than 3.5% per year, with no significant difference between the first and the second year of observation. Women in the quintile with the highest trabecular bone mass (328 to 458 mg/cm3 at baseline) are slow losers. These women show an absolute loss of 3 mg/cm3 per year, while the women in the lowest quintile (102 to 210 mg/cm3 at baseline), with a proportion of 64% fast losers, lose an average of 10 mg/cm3, irrespective of age, number of fertile years, age at menopause and body-mass index. The bone masses in the metaphyseal compact bone remain constant.2+ a screening program before architectural changes in trabecular bone reach a critical point (i.e. in the reversible stage of osteoporosis), these women can be reliably identified within six months and monitored effectively and economically. With the general risk factors of postmenopausal osteoporosis an individual's risk of rapid bone loss cannot be predicted or determined; therefore, the precise measurement of purely trabecular bone is indispensable.

Aged↗
PubMed1994

[Problems with bone densitometry].

Today, bone density can be measured by different technical methods which show variations in terms of reproducibility, accuracy and sensibility. A crucial parameter is the reproducibility, which differs considerably from method to method. With densitometric methods it is possible not only to evaluate patients at risk getting an osteoporosis but also to establish an individual prophylaxis and therapy by means of highly precise quantitative methods, based on the parameters 'bone density' and 'loss of bone density'. A high bone turnover leads to fast bone loss and, vice versa, fast bone loss, measured by densitometry, is correlated with high bone turnover in postmenopausal women. This allows to establish an individual therapy with antiresorption resp. bone-stimulating agents and the knowledge about a tailored, individual treatment increases patients' compliance and reduces the rate of 'non-responders'.

Aged↗
PubMed1992

Images of nephrology nursing practice: report of a survey.

The results of a survey designed to identify existing images of nephrology nursing practice are reported. The sample included 374 attendees at meetings sponsored by the American Nephrology Nurses' Association (ANNA). Content analysis revealed that the typical nephrology patient is elderly, has a chronic illness and negative affect, is not compliant, and is dependent on others. The typical nephrology nurse-patient interaction emphasizes teaching and support. The most common nursing activities are assessment, teaching, dialysis treatment, and psychological support.

Attitude of Health Personnel↗
PubMed1990

Preparing for inspection: a tool to maximize quality and minimize risk.

Self-assessment of a dialysis unit can provide an effective means of improving or assuring the level of quality the unit provides in delivering safe and effective care. A tool for use by facility personnel was developed and is being used in 12 dialysis units within one dialysis company. This tool has been useful in identifying areas of risk and in assisting units in developing and maintaining survey readiness. This article presents the facility tool and describes how it may be used to assist other dialysis facilities in risk management and quality assurance activities.

Hemodialysis Units, Hospital↗
PubMed1988

Characterization of two different human cytomegalovirus glycoproteins which are targets for virus neutralizing antibody.

In previous studies we have identified two viral polypeptides detected by murine monoclonal antibodies which neutralize the infectivity of human cytomegalovirus (CMV) AD169. One is an 86,000-Da polypeptide (p86) and the second is a complex of two major coimmunoprecipitating polypeptides of 130,000 and 55,000 Da (p130/55). In this study we have shown that the two viral polypeptides are immunologically unrelated and have distinct peptide cleavage patterns. We have characterized these polypeptides as glycoproteins and studied their biosynthesis in human embryonic lung cells. The oligosaccharides found on both the p86 and the p130/55 were characterized by endoglycosidase digestion as N-linked high-mannose carbohydrates. Inhibitors of glycosylation were used to further characterize the oligosaccharides. Tunicamycin, which inhibits the biosynthesis of N-linked oligosaccharides on the endoplasmic reticulum, inhibited both the infectivity and biosynthesis of the p86 and p130/55. The underglycosylated forms in tunicamycin-treated cultures could be detected only under conditions of pulse-labeling with L-[35S]methionine. Monensin, which inhibits the modification of glycoproteins from simple to complex forms in the Golgi, reduced viral infectivity at concentrations which had no effect on viral protein synthesis, but did not alter the apparent molecular weight of either the p86 or the p130/55. The oligosaccharides were critical for the in vitro immunologic reactivity of the p86 in immunoblots. However, endoglycosidase F-treated p86 was comparable to the native form in inducing virus neutralizing antibody in guinea pigs. Endoglycosidase F-treated p130/55 retained its ability to bind antibody in Western blots.

Antibodies, Monoclonal↗
PubMed1985

The microvasculature of the small-intestinal mucosa of the rat: quantification of hemodynamic effects of topically applied cimetidine, ranitidine, somatostatin, and vasopressin.

The influence of topically administered cimetidine, ranitidine, somatostatin, and vasopressin on microvessels of the jejunal villus of the rat was investigated by means of an in vivo videomicroscopy technique. For all substances a dose-response curve concerning the change of vessel diameters was obtained. All four drugs induced a significant vasoconstriction at the capillary level. Maximum vasoconstriction was achieved with vasopressin. These results strongly suggest the presence and possibly importance of H2 receptors in the intestinal vascular bed of the rat.

Animals↗