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Biomedical subjects

R Wolff

Publications and source records attributed to R Wolff.

At least 55 records · Page 3Linked to original sources
PubMed1987

Variable number of tandem repeat (VNTR) markers for human gene mapping.

A large collection of good genetic markers is needed to map the genes that cause human genetic diseases. Although nearly 400 polymorphic DNA markers for human chromosomes have been described, the majority have only two alleles and are thus uninformative for analysis of genetic linkage in many families. A few known marker systems, however, detect loci that respond to restriction enzyme cleavage by producing a fragment that can have many different lengths. This polymorphism is due to variation in the number of tandem repeats of a short DNA sequence. Because most individuals will be heterozygous at such loci, these markers will provide linkage information in almost all families. Ten oligomeric sequences derived from the tandem repeat regions of the myoglobin gene, the zeta-globin pseudogene, the insulin gene, and the X-gene region of hepatitis B virus, were used to develop a series of single-copy probes. These probes revealed new, highly polymorphic genetic loci whose allele sizes reflected variation in the number of tandem repeats.

Chromosome Mapping↗
PubMed1987

Characterization of a human 'midisatellite' sequence.

We have examined the structure and DNA sequence of a human genomic locus that consists of a large hypervariable region made up of repeats of a simple sequence. With several restriction enzymes, the locus shows many restriction fragments that vary quantitatively as well as qualitatively. Other restriction enzymes produce only a single, high-molecular-weight fragment at this locus. Almost all of the fragments are revealed with a simple sequence probe. Southern transfers of the high-molecular-weight restriction fragments produced by the restriction enzymes NotI and SfiI, resolved by pulsed-field gel electrophoresis, gave at most two fragments, demonstrated to be allelic, showing that the majority of the restriction fragments seen in the complex patterns are at a single locus. The estimated size of the region homologous to the probe varied from 250 to 500 kilobases. DNA sequencing indicated that the region consists of tandem repeats of a 40-base-pair sequence. Some homology was detected to the tandem repeating units of the insulin gene and the zetaglobin pseudogene hypervariable regions, and to the "minisatellite" DNA at the myoglobin locus.

Base Sequence↗
PubMed1987

[Theoretical principles of cemented prostheses].

Today total hip replacement has become a routine procedure in older patients all over the world. A good result is to be expected only, if the device will meet the following requirements: adequate force transfer to the bone, adequate stiffness and elasticity, sufficient range of motion, biocompatibility of the material, low friction, low rate of wear, sufficient lubrication and a secure anchorage. Up to now, the weak point is the bone cement. Advancements in its composition and improved cement techniques will guarantee good function without pain during a long enough period of time.

Biomechanical Phenomena↗
PubMed1987

[Apophyseal rupture of the pelvis and lower extremity caused by sports].

Apophyses are secondary ossification centers and serve as the insertion or origin of tendons. They are under a dynamic but not static load. During sexual maturity, they represent a weak point in the locomotor system. Apophyseal injuries can apparently be attributed to an incongruity between load tolerance and increased strain on the seam of the apophysis. The majority of these injuries occur during sports and involve men more frequently than women. The injury is often primarily misinterpreted as a pulled-muscle. The treatment method is dependent on the localization of the injury and the extent of the fragment dislocation.

Adolescent↗
PubMed1986

Interaction of thrombospondin with resting and stimulated human platelets.

The interaction of isolated and radioiodinated thrombospondin with washed human platelets has been characterized. The ligand bound to nonstimulated and thrombin-stimulated platelets in a time-dependent manner, and apparent steady state was reached within 25 min. Binding was not due to iodination of the ligand and was inhibited by nonlabeled thrombospondin but not by unrelated proteins, and bound ligand was identical with thrombospondin in terms of subunit structure. Nonlinear curve-fitting analyses of binding to resting platelets suggested the presence of a single class of sites which bound 3,100 +/- 1,000 molecules/platelet with an apparent Kd of 50 +/- 20 nM. This interaction was not attributable to contaminating cells or inadvertant platelet activation. Binding to thrombin-stimulated platelets had a lower apparent affinity (Kd = 250 +/- 100 nM) and higher apparent capacity (35,600 +/- 9,600 molecules/platelet). Thrombin-enhanced binding was dependent upon agonist dose and platelet stimulation. Fibrinogen, a monoclonal antibody to GPIIb-IIIa, temperature, and divalent ions had differential effects upon thrombospondin binding to resting and stimulated platelets, suggesting the presence of two distinct mechanisms of thrombospondin binding to platelets. While thrombospondin binding to thrombin-stimulated platelets occurs with characteristics similar to those observed for fibrinogen, fibronectin, and von Willebrand Factor, its high affinity interaction with resting platelets is unique to this adhesive glycoprotein.

Binding, Competitive↗
PubMed1985

RNA synthesis in male pronuclei of the sea urchin.

Transcription in male pronuclei of fertilized sea urchin eggs was measured by comparison of [3H]uridine incorporation into RNA in polyspermic, monospermic and activated eggs under conditions where uptake of the isotope and conversion to UTP were equivalent. RNA accumulation from male pronuclei begins by S phase of the first cell cycle. Initiation of this RNA synthesis does not require DNA synthesis. A major fraction of the newly synthesized transcripts are mRNAs coding for early embryo (alpha-) histones. In addition, several other unidentified transcripts are detected by gel electrophoresis. The pattern of RNA transcription remains constant for at least 4 h post-fertilization. These results demonstrate that specific transcription of male pronuclear sequences is activated in the first cell cycle following fertilization.

Animals↗
PubMed1984

Satiation in the treatment of inappropriate fire setting.

This paper concerns the treatment of a 7-yr-old boy, who exhibited multiple behavioral disorders, and was treated in a residential setting for inappropriate fire setting by a satiation procedure. Throughout treatment the number of adult interventions at home to "correct him about fire" were recorded. Treatment consisted of 100 30-min sessions in the residential setting during which he was free to light as many matches as he wished. Contrary to earlier studies, the number of matches lit per therapy session did not decrease. However, the number of "corrections about fire" at home completely ceased midway through treatment, and did not recur through the 24-month follow-up period.

Behavior Therapy↗
PubMed1982

[Arthrodesis and external fixation].

Though operative arthrodesis is less often indicated than before, in the knee and upper-ankle joints it is more successful than artificial joints. In cases of irreparable neuro-paralysis it is often the only alternative for the lower extremities. Today's external fixation and the standardization of its operative technique make good stability possible, thus improving preconditions for consolidation of the resected articular surfaces, above all for the knee and upper-ankle joints. On the basis of 158 arthrodeses performed over a period of 10 years indications, technique and success rate are described.

Ankle Joint↗
PubMed1980

Elementary step dynamics of catalytic hypercycles.

Two model systems for hypercyclic organisation constructed from a series of uni- and bimolecular reaction steps were studied under the condition of unlimited growth by means of qualitative analysis and numerical integration of the corresponding differential equations. It is shown that both models lead, within wide ranges of parameter and initial conditions, to the same characteristic dynamical behaviour as the elementary hypercycles and hypercycles with translation introduced in 1978 by Eigen and Schuster.

Kinetics↗
PubMed1980

[Implications of the incorporation of transisomers of unsaturated fatty acids into cell membranes].

The incorporation of dietary trans fatty acids is shown into intestinal brush border and heart mitochondrial membranes obtained from rats fed with either partially hydrogenated soybean oil or with a synthetic triglyceride containing elaidic or linelaidic acid. The distribution of dietary linelaidate in the major phospholipid classes from inner membranes of mitochondria is determined. Heart mitochondria from normal rats and linelaidic acid fed rats are compared with respect to their swelling rate and their oxidative phosphorylation. The influence of dietary linelaidate on the activity of some brush border-associated enzymes is also studied. On the basis of the authors' observations and those made by others with microorganism cels or models of biological membranes (liposomes and monomolecular films), the possible implications of trans fatty acids incorporation on membrane functions are reviewed.

Animals↗