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Biomedical subjects

K Wolf

Publications and source records attributed to K Wolf.

At least 145 records · Page 8Linked to original sources
PubMed1991

The mitochondrial genome of Schizosaccharomyces pombe. Stimulation of intra-chromosomal recombination in Escherichia coli by the gene product of the first cox1 intron.

The open reading frame of the first intron of the mitochondrial cox1 gene (cox1I1) was expressed in Escherichia coli. The putative intron-encoded protein stimulated the formation of intra-chromosomal lac(+)-recombinants about threefold. No stimulation was found when the reading frame was inserted in the opposite direction, or when it was interrupted by a deletion. The intronic open reading frame did not complement recA- or recB- mutants of E. coli. In S. pombe, elimination of this intron did not abolish homologous recombination in mitochondria. A possible role of the recombinase activity in yeast mitochondria will be discussed.

Amino Acid Sequence↗
PubMed1991

Chlorinated solvents: will the alternatives be safer?

Over the next decade, use of chlorinated solvents, a widely employed class of chemicals, will decline significantly because of increasingly stringent environmental regulations. These solvents pose certain health and environmental problems and they have been heavily scrutinized. The alternatives to the solvents are being adopted without controls. In some cases, these substances will pose other health and environmental problems that are likely to be as serious; in other cases, the alternatives have not been examined for their health and environmental effects at all. This case study demonstrates that regulations on chlorinated solvents and their potential alternatives are inconsistent with one another and conflicting.

Air Pollution↗
PubMed1991

The iliac crest region: donor site for vascularized bone periosteal and soft tissue flaps.

A review is presented of the classic vascularized iliac crest transfer and to show useful variations on this technique. A technical variation to reconstruct mandibular defects, the semisegmented iliac crest graft, is described. Another variation, the half iliac crest graft, is presented for use in the neovascularization of avascular necrosis of the femoral head. When such a flap is raised with a large periosteal flap and overlying muscle or skin, or both, as a composite flap, a primary osteoperiosteal tube can be created to reconstruct segmental defects in long bones. This primary osteoperiosteal tube is secondarily transformed into a completely osseous tube.

Bone Transplantation↗
PubMed1991

Retinal eccentricity of fusion detail affects vergence adaptation.

Adaptation of tonic vergence ("vergence adaptation" or "prism adaptation") may be produced by sustained accommodative, disparity, or proximal vergence innervation. Phoria measures were used in the present study as indices of tonic vergence adaptation to convergence and divergence stimuli in five subjects. Amblyoscope targets stimulated fusion either over the central or peripheral retina while holding accommodative and proximal stimuli constant. The magnitude and rate of tonic vergence adaptation were greater under the central fusion condition than under the peripheral fusion condition, even though the vergence stimuli were matched between central and peripheral fusion conditions. These results show that tonic vergence adaptation is influenced by the retinal eccentricity of target fusional patterns. However, additional work is required to identify the mechanism(s) underlying this eccentricity effect.

Adaptation, Ocular↗
PubMed1991

[Does parenteral linoleic acid modify tumor growth? Studies with the Yoshida sarcoma model].

In an experimental study with sprague-dawley-rats we tested the effect of parenteral substituted LCT-fats on tumor growth of the Yoshida sarcoma in its ascites form. Therefore we tested 4 groups with 10 tumor-bearing and 10 non-tumor-bearing rats. We added group 1-3 LCT-fats in different doses. Group 4 was fed enterally. We found that tumor-bearing rats had a higher nitrogen retention than non-tumor-bearing rats. Non-tumor-bearing rats showed a higher nitrogen concentration in the muscles. The portion of nitrogen increased with increasing portion of fat. The content of nitrogen in the ascites, the quantity and the number of tumor cells was reversed in proportion to the portion of fat. For the host we showed that he cannot make use of the energy directly. The tumor does not grow in proportion to the available energy but has to support itself from the catabolism of the host.

Animals↗
PubMed1991

[Plastic surgery measures in combined soft tissue defects of the lower leg].

Isolated or combined soft tissue defects of the lower leg are still a challenge as regard diagnostic and differential treatment. We distinguish acute and chronic isolated or combined soft tissue defect. Acute trauma within a multiple injury pattern is a special form of the acute soft tissue defect. For diagnostic purposes we use a preoperative and intraoperative standardized diagnostic programme. A new classification oriented towards the therapeutic procedure is presented, as is therapy algorithm which has been created.

Follow-Up Studies↗
PubMed1991

[Vascularized periosteal transplant. A review of a new therapeutic possibility].

The idea of using vascularized periosteal flaps in reconstructing bone defects is more than one hundred years old. Up to now, experimental and clinical results regarding their osteogenic capacity have been a subject of debate. Experimental and clinical studies over the last ten years were able to demonstrate osteogenic capability of such vascularized periosteal flaps, provided the periosteum is well vascularized. To insure intact microcirculation, vascularized periosteal flaps must be freed up by sharp dissection. Small pieces of bone may be removed with the periosteum, whereas the periosteum must remain uninjured. There are many known donor sites in man: the iliac crest, the distal femur, the distal humerus and the tenth rib. There are no reports concerning donor site morbidity. Besides its osteogenic capacity, the periosteal flaps have "shape giving" and "space limiting" functions. The given volume within a periosteal flap rolled into a tube is the basis for the "Concept of the Given Space": the space within the tube defines where bone formation will occur, there being no loss of bone into the surrounding soft tissue. Because of the vascularized periosteal flap's fragility and the good results of other reconstructive procedures for segmental bone defects, there are few indications for extremity reconstruction using periosteal flaps: pseudarthrosis in the upper extremity is one example. In the lower extremity, a combination of vascularized periosteum with conventional and mainly vascularized bone grafts offers interesting possibilities for reconstruction.

Animals↗
PubMed1991

[Tarsal tunnel syndrome. Nerve compression syndrome in the foot].

Pathological changes in sensation over the sole of the foot do not always correspond to the full area of distribution of the posterior tibial nerve. Some neurologists advise separate examination of the tibial nerve, the medial and lateral plantar nerves, in order to ascertain whether either or both might be affected. 60 preparations of cadaveric feet in the Department of Anatomy were examined. Using a measuring grid, the position and size of the nerves in the tarsal tunnel were assessed and the facial band which define and divide the osteofibrous canal delineated. The corners of the measuring grid were the tip of the medial malleolus (A), the tip of the calcaneal tubercle at its greatest distance from the medial malleolus (B) and the tuberosity of the navicular bone (C). These points can also be clearly identified clinically. They define a triangle whose sides A-B and B-C are of constant equal length and whose base A-C varies little. The operative approach includes a T-shaped incision of the retinaculum. The vertical line of the T lies underneath the skin incision. The horizontal line corresponds with the upper border of the abductor hallucis muscle. The upper border of the abductor hallucis is defined and the muscle retracted medially to expose the deep fascia. This layer is removed together with the connective tissue bridge which stretches between the fascia and the calcaneus. The plantar nerves are discovered and run to the sole of the foot without further obstruction.

Diagnosis, Differential↗
PubMed1991

Bone grafting in rearfoot surgery.

Bone grafting, especially in rearfoot surgery, is occasionally required. Two main morphologic types of bone may be grafted, namely cortical and cancellous. Each type of bone has its unique characteristics, which, when used properly, will ensure a good surgical result. Other factors also play an important role in decision making when using bone grafts. These factors include the characteristics of the host and site into which the graft will be placed, the fixation of the bone graft site, the metabolic state of the host, and the function of the graft. If careful surgical planning is exercised, a successful surgical result can be expected.

Bone Transplantation↗
PubMed1990

The Mu1 transposable element of maize contains two promoter signals recognized by the Escherichia coli RNA polymerase.

The galactokinase (GalK) expression plasmid vector system pKO-1 has been used to screen for promoter elements in the maize transposable element Mu1 that function in Escherichia coli. Two transcriptional start points, named S1 and S2, were identified, which are located in the two direct repeats of the transposable element. This paper demonstrates that sequence elements exist in a plant transposable element which function as prokaryotic promotors.

Base Sequence↗
PubMed1990

Interactions between the yeast mitochondrial and nuclear genomes: isogenic suppressive and hypersuppressive petites differ in their resistance to the alkaloid lycorine.

In a previous paper we have shown that the alkaloid lycorine inhibits growth of rho+, mit- and rho-, strains of Saccharomyces cerevisiae, whereas strains devoid of mitochondrial DNA (rho degrees) are resistant to more than 200 micrograms/ml of the alkaloid. In this report we show that hypersuppressive petites are almost as resistant as rho degrees mutants, whereas isogenic rho- petites, which have retained longer segments of the genome, are sensitive to the drug.

Amaryllidaceae Alkaloids↗
PubMed1990

Morphological detection and quantification of lipoprotein(a) deposition in atheromatous lesions of human aorta and coronary arteries.

Lipoprotein(a), as an atherogenic particle, represents an independent risk factor for coronary heart disease. In the present study the morphological distribution of apoprotein (a) and apoprotein B within the arterial wall is described. Apoprotein B, a constituent of very low-density lipoprotein, low-density lipoprotein and lipoprotein(a) has previously been demonstrated in atheromatous lesions. Lipoprotein(a) possesses an additional protein, designated apoprotein (a). Autopsy material (n = 74) from the left coronary artery and from the thoracic aorta has been examined by means of immunohistochemistry and both apoprotein (a) and apoprotein B were detected, primarily associated with the extracellular matrix and accumulating in lesions in the arterial wall. The staining pattern for both antigens was almost always found to be congruent, suggesting that the detection of (a)-antigen has to be attributed at least in part to the presence of lipoprotein(a). It is concluded that both low-density lipoprotein and lipoprotein(a) have an important role in the pathogenesis of atherosclerosis.

Adolescent↗
PubMed1990

Lipoprotein(a) in the arterial wall.

We compared CHD patients with healthy blood donors to confirm the role of Lp(a) as an independent risk factor. More important, we performed biochemical and immunohistochemical studies to evaluate the potential mechanism by which Lp(a) causes CHD. We measured the Lp(a) concentration in comparison with other lipoprotein parameters in fresh human arterial wall biopsies and, in autopsy tissue, we localized apo (a) and apo B, as well as fibrin, with immunohistochemical methods in different vessel areas. Density gradient ultracentrifugation was used to analyse lipoprotein fractions isolated from human arterial wall. Lp(a) accumulates in the intima, preferentially in plaque areas, dependent on the serum Lp(a) level. Most of the Lp(a) can be located extracellularly, but apo(a) can also be detected in foam cells. A strong co-localization has been observed for apo(a) and apo B; only a few areas containing only apo B were detected. Moreover, a striking co-localization for apo(a) and fibrin was found. The possibilities for the pathways by which Lp(a) enters the arterial wall and accumulates extracellularly are discussed on the basis of the present data and recent data published by other groups.

Aorta↗
PubMed1990

Cutaneous angiosarcoma. A literature review and case report.

A case of angiosarcoma of the lower extremity was presented. This rare but highly malignant soft tissue tumor usually presents as a raised pigmented lesion. Wide surgical excision or amputation is the treatment of choice. Radiotherapy may offer some relief in cases that are inoperable.

Adult↗