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Biomedical subjects

G Wolf

Publications and source records attributed to G Wolf.

At least 19 recordsLinked to original sources
PubMed1992

Nitric oxide synthase in rat brain is predominantly located at neuronal endoplasmic reticulum: an electron microscopic demonstration of NADPH-diaphorase activity.

Nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) of the rat brain, apparently identical with nitric oxide (NO) synthase, was demonstrated at the electron microscopic level by means of the tetrazolium salt 2-(2'-benzothiazolyl)-5-styryl-3-(4'-phthalhydrazidyl)tetrazolium chloride (BSPT). BSPT is a non-osmiophilic compound that yields an insoluble, osmiophilic, and lipophobic formazan on reduction. The reaction product was deposited sharply on membranes of the endoplasmic reticulum including the nuclear envelope. Other membrane structures were, as a rule, free of reaction product, likewise mitochondria. Occasionally, however, the outer membrane of mitochondria was labeled, and their contents displayed a homogeneous, medium electron density. The findings suggest that NADPH-d, i.e. neuronal NO synthase, is a predominantly membrane-bound enzyme, which is ubiquitously distributed in cells of brain tissue, but highly concentrated in nerve cells described as 'NADPH-d-positive' at the light microscopic level.

Amino Acid Oxidoreductases↗
PubMed1992

Memantine prevents quinolinic acid-induced hippocampal damage.

Memantine, used as a drug for treatment of spasticity and other extrapyramidal disorders as well as dementia, was shown to prevent brain damage caused by the glutamate (N-methyl-D-aspartate, NMDA) receptor agonist, quinolinic acid. Studies were focused on the hippocampal formation which is known to be highly vulnerable to quinolinate. Pretreatment of animals with memantine added to the food led to a reliable protection of hippocampal neurons when the drug was administered chronically for a period of 10 days prior to quinolinate exposure (i.c.v. injected). Additional i.p. administration of memantine (simultaneously with quinolinic acid or up to 24 h later) did not substantially add to the protective potency of the memantine diet. Our findings indicate that memantine may have beneficial effects in the treatment of brain disorders which are mediated by excitotoxic effects of glutamate.

Animals↗
PubMed1992

The effect of sphingosine and phorbol ester on the signal transduction enzymes and fibronectin release in cell culture.

In testing the hypothesis that the stimulation of the release of fibronectin (FN) by 12-O-tetradecanoylphorbol 13-acetate (TPA) from human lung fibroblasts in culture is the result of activation of protein kinase C (PKC), we found that the PKC inhibitor sphingosine strongly inhibited FN release in presence and even in absence of TPA. However, a different PKC inhibitor, calphostin C, despite almost complete inhibition of PKC, had no effect on FN release. We concluded that sphingosine is a potent inhibitor of FN release from the cell surface, independent of its inhibition of PKC; and that TPA stimulates release of FN by a pathway other than activation of PKC. We found that the activation of PKC by TPA was accompanied by inhibition of the cAMP-dependent protein kinase (PKA). When PKA was inhibited by an antagonist (H8, a cAMP analogue) at a concentration specific for PKA inhibition, the release of FN was stimulated similar to the stimulation with TPA. Activation of PKA with forskolin resulted in decreased FN release. In conclusion, we have shown that: (1) sphingosine had a robust effect inhibiting the release of FN from fibroblasts, independent of its action on PKC; (2) TPA treatment of these cells resulted in inhibition of PKA; (3) inhibition of PKA stimulated FN release whereas its activation decreased this release. It is possible that PKA, by phosphorylating a protein, may function, directly or indirectly, in keeping FN attached to the cell surface of fibroblasts.

Cell Line↗
PubMed1992

Unexpected, late cardiovascular effects of surgery for peripheral artery disease. Veterans Affairs Cooperative Study 199.

In reviewing late morbidity of a multicenter clinical trial comparing balloon angioplasty (percutaneous transluminal angioplasty) with bypass surgery for lower-extremity ischemia, an unexpectedly high incidence of adverse systemic events in surgical patients was uncovered. The study was prospective and randomized, and included a total of 263 patients, with follow-up from 2 to 6 years. When end points of related deaths, amputations, and intervention failures were summed, surgery was favored over percutaneous transluminal angioplasty at 4 years. Progression of cardiac and renal dysfunction and mortality differed between groups. A total of 42 deaths were in the group who underwent surgery and 27 in those who underwent percutaneous transluminal angioplasty. The percentage difference in death rate between the two groups increased each year to reach 10% at 5 years. A significant difference in renal function was noted in nine patients who underwent surgery and zero who underwent percutaneous transluminal angioplasty. Myocardial infarctions were greater on follow-up of surgical patients. After 6 years, congestive heart failure had occurred in 19 patients who underwent surgery and eight who underwent percutaneous transluminal angioplasty. The trends in this study of patients with only moderately severe peripheral arterial disease suggest an increased rate of deterioration of cardiac and renal function in patients who have arterial operations. In surgical patients, mortality was 13.1% per year, whereas it was 8.4% for patients treated with percutaneous transluminal angioplasty. Future intervention studies should include long-term follow-up of such cardiovascular events.

Amputation, Surgical↗
PubMed1992

Parthenogenetic activation of human oocytes by puromycin.

OBJECTIVE: Our objective was to obtain parthenogenetic activation of unfertilized human oocytes by puromycin and to try to use this procedure for cytogenetic purposes. SETTING: The setting was our IVF laboratory. METHODS: Eighty-two spare oocytes from 34 IVF patients were used. In the first series of experiments 39 unfertilized oocytes were cultured in medium containing 100, 50, or 10 micrograms/ml puromycin for 6 to 24 hr. After the appearance of pronuclei they were transferred to plain medium, further cultured, and cytogenetically analyzed. In the second series of experiments 43 oocytes were cultured for 5 to 10 hr in 10 micrograms/ml puromycin, transferred to plain medium, and fixed for cytogenetic analysis 2 hr after nuclear envelope breakdown. RESULTS: Ninety-one percent of the oocytes in the first experiment showed the presence of one or more nuclei. From the pronucleate oocytes additionally cultured in puromycin-free medium, 46% developed further to the metaphase of the first mitotic division or the two-cell stage and 54% remained arrested at the pronuclear stage. In the second experiment 88% of the treated oocytes showed pronuclei or had cleaved, and after withdrawal from puromycin 96% of the pronucleate oocytes entered mitosis. CONCLUSION: Puromycin induces haploid as well as diploid parthenogenesis in aged human oocytes. A 5- to 10-hr treatment of oocytes with 10 micrograms/ml puromycin yields the highest percentage of activation, and almost all parthenogenetically activated oocytes enter or develop beyond the first cleavage mitosis. Analysis of mitotic metaphase chromosomes from parthenogenetically activated human oocytes may be a promising new approach to preimplantation cytogenetics.

Cell Division↗
PubMed1992

Radiologic anatomy of the paranasal sinuses in the child.

The development of the paranasal or accessory sinuses begins very early in utero. In the newborn the ethmoidal sinus, which gives rise to all the other sinuses, as well as the maxillary sinus, can already be identified on x-rays. The frontal sinus appears as a triangle at the age of four and oversteps the supraorbital margin at the age of six. The sphenoidal sinus begins to excavate the concha sphenoidalis at the age of four and can be seen on x-rays at the age of eight, when it extends to the hypophyseal fossa. In the twelve-year-old child all sinuses almost reach their final sizes. However, the size and shape of all sinuses, particularly of the frontal and the sphenoidal sinuses are very different.

Cephalometry↗
PubMed1992

Metabolism of very low density lipoproteins in the pig. An in vivo study.

1. The metabolism of apolipoprotein B (apoB) was investigated in pigs injected with [125I]very low density lipoproteins (VLDL) to determine to which extent the two distinct low density lipoprotein subclasses (LDL1 and LDL2) derive from VLDL. 2. The lipoproteins were isolated by density gradient ultracentrifugation and the transfer of radioactivity from VLDL into LDL1 and LDL2 apoB was measured. 3. Only a minor portion of VLDL apoB was converted to LDL1 (7.7 +/- 3.2%) and LDL2 (3.6 +/- 1.5%), respectively. Thus, we conclude that the major portion of LDL, especially LDL2, is synthesized independently from VLDL catabolism.

Animals↗
PubMed1992

Pentylenetetrazol kindling and factors of glutamate transmitter metabolism in rat hippocampus.

Male Wistar rats administered repetitively with pentylenetetrazol developed a dose-dependent enhancement of seizure behaviour referred to as pentylenetetrazol kindling. After a daily dose of 40 mg pentylenetetrazol/kg or physiological saline (control rats) injected intraperitoneally for a period of two weeks, hippocampal tissue was studied autoradiographically for high-affinity uptake of [3H]glutamate and, by activity staining, for aspartate aminotransferase and glutamate dehydrogenase. Most prominent changes were found in neuropil areas known to be endowed with glutamatergic structures. The uptake capacity of glutamate decreased by 48% (maximum rate), whilst activities of aspartate aminotransferase and glutamate dehydrogenase elevated to 140 and 130%, respectively. Cytochrome c oxidase activity was found to be unaffected. The findings indicate an important role of factors of the glutamate metabolism in the kindling process with respect to the production, utilization, and availability of transmitter glutamate.

Animals↗
PubMed1992

Isolation and characterization of cDNA from renal tubular epithelium encoding murine Rantes.

We have been interested in identifying proinflammatory molecules which might play a role in attracting monocytes and T cells to the kidney. Some of the new intercrines are potential candidates. In this report we have isolated cDNA encoding murine Rantes (MuRantes) from renal tubular epithelium (MCT cells). MuRantes is a 91 amino acid member of the -C-C- or intercrine beta subgroup of the Scy superfamily. The amino acid sequence for mature MuRantes was deduced from its coding cDNA and was found to be 90% homologous to its mature human counterpart (HuRantes). MCT epithelium expresses a single mRNA transcript for MuRantes of approximately 1100 bp. The MuRantes protein could be detected in cell lysates of MCT epithelium by western blotting and in the cytoplasm of MCT cells by immunofluorescence using a polyclonal antibody generated against HuRantes fusion protein. A search protocol using MuRantes-specific primers and cDNA amplification revealed that mRNAs for MuRantes are expressed additionally in syngeneic mesangial cells (MMC cells), whole kidney, liver, and spleen, as well as in nephritogenic antigen-specific CD4+ helper and CD8+ effector T cells. cDNA amplification studies also demonstrated a significant elevation in mRNA transcripts encoding MuRantes in response to the stimulation of MCT epithelium with TNF alpha and IL-1 alpha in culture, but not with TGF beta, gamma IFN, or IL-6. Our findings indicate that proximal tubular epithelium is an authentic source of MuRantes, and that transcripts encoding MuRantes are responsive to the modulating influence of paracrine factors having a known role in the development of parenchymal injury.

Amino Acid Sequence↗
PubMed1992

High glucose-induced proliferation in mesangial cells is reversed by autocrine TGF-beta.

We investigated the effects of glucose concentration in serum-free media on the proliferative growth response of a cultured murine mesangial cell line. Raising the ambient D-glucose concentration from 100 mg/dl to 450 mg/dl stimulated cell proliferation after 24 to 48 hours but had a growth inhibitory effect after 72 to 96 hours of incubation. This biphasic proliferative response to high glucose concentration was not mediated by the elevated osmolarity of the medium and did not occur when L-glucose was used. The early phase of glucose-induced proliferation was associated with increased expression of the immediate early genes c-myc and egr-1 as well as with induction of the S-phase related proliferating nuclear cell antigen (PCNA). Several lines of evidence indicated that the late phase of glucose-induced growth inhibition was mediated by the bioactivation of endogenous transforming growth factor beta (TGF-beta). Neutralizing antibody against TGF-beta prevented the late inhibitory effects of glucose on proliferation. On the other hand, exogenous TGF-beta (1 ng/ml) significantly inhibited basal proliferation in mesangial cells. Furthermore, Northern blot analysis revealed that TGF-beta 1 mRNA was induced by 450 mg/dl glucose in the medium after 48 to 72 hours, but not after 24 hours. Cell cycle analysis demonstrated that mesangial cells incubated in high glucose for 24 hours have a higher percentage of cells in the S-G2 phase of the cell cycle compared with cells grown in normal glucose concentration. After 48 hours of culture in elevated glucose concentration, the percentage of cells in S-G2 phase was decreased, and became comparable to that of cells in normal glucose concentration. However, the addition of neutralizing anti-TGF-beta antibody stimulated the progression of cells towards S-G2 in high glucose medium after 48 hours. The findings of this study demonstrate a biphasic growth response of mesangial cells when they were cultured in high glucose concentration; initially there was a transient stimulation of replication for 24 to 48 hours followed by a sustained inhibition after longer incubation periods. This inhibition may be mediated by the glucose-induced synthesis and/or bioactivation of TGF-beta which can inhibit proliferation of mesangial cells in an autocrine fashion.

Animals↗
PubMed1992

Skin island flaps supplied by the vascular axis of the sensitive superficial nerves: anatomic study and clinical experience in the leg.

An anatomic study performed on 64 fresh injected legs has shown the role of the vascular axis that follows the superficial sensitive nerves in supplying the skin. Three nerves were studied: the saphenous nerve, the superficial peroneal nerve, and the sural nerve. Conclusions are the same for the three nerves: The vascular axis, which can be either a true artery or an interlacing network, ensures the vascularization of the nerves, gives off several cutaneous branches in the suprafascial course of the nerve, and anastomoses with the septocutaneous arteries issuing from a deep main vessel. The superficial nerves that course the leg can therefore be considered as vascular relays owing to their neurocutaneous arteries. The concept of a neuroskin island flap has been developed and applied to six clinical cases for coverage of some specific areas of the knee and of the lower part of the limb.

Adult↗
PubMed1992

Cellular retinol-binding protein functions in the regulation of retinoid metabolism.

A microsomal retinyl ester hydrolase from rat tissues is activated by apo-cellular retinol-binding protein, which thus regulates the availability of retinol either for binding to serum retinol-binding protein or for metabolic oxidation. Microsomal retinal synthesis was found to occur in rat tissues with holo-cellular retinol-binding protein as substrate. Retinal could be further oxidized to retinoic acid by a cytosolic fraction.

Animals↗
PubMed1992

Effects of angiotensin II on proximal tubular cells stably transfected with the c-mas oncogene.

Angiotensin II (ANG II) normally induces cellular hypertrophy in proximal tubular epithelium by engaging receptor systems that use a G-protein-signaling mechanism. The c-mas oncogene also encodes part of a superfamily of vasoactive peptide receptor-like moieties that couple to G proteins. To determine whether the stable expression of the c-mas gene might alter or modify the induction of cellular hypertrophy by ANG II in tubular epithelium, a rat c-mas cDNA was cloned into the pSV2 expression vector for use in cell transfection. Scatchard analysis of ANG II binding revealed no significant differences in ANG II receptor number or in the dissociation constant between pSV2mas-transfected or wild-type MCT cells, but rather an increase in the number of receptors not replaceable by known inhibitors. ANG II also induced proliferation in pSV2mas-transfected MCT cells that was not blocked by conventional inhibitors and increased intracellular levels of inositol trisphosphate. ANG II, furthermore, did not increase de novo protein synthesis in pSV2-transfected MCT cells and failed to lower their intracellular concentration of adenosine 3',5'-cyclic monophosphate, both expected parameters of cellular hypertrophy. Our findings demonstrate that expression of c-mas in tubular epithelium can modulate tubular cell phenotype toward proliferation rather than hypertrophy. This effect is likely mediated by a reshuffling of the heterogeneity of ANG II receptors on the cell surface, or perhaps by the emergence of a new ANG II receptor, followed by alterations in the process of signal transduction.

Angiotensin II↗
PubMed1992

Increases in levels of collagen types I and IV messenger ribonucleic acid in murine kidneys after treatment with ciclosporin.

We investigated changes in the levels of mRNA transcripts encoding types I and IV collagen in the kidney following the administration of ciclosporin (CS) in mice. Daily doses of CS increased the levels of mRNAs encoding collagen types I and IV in whole kidneys harvested 4 weeks after treatment. At this time point, neither a reduction of renal function detected by serum creatinine, nor histologic evidence of interstitial damage were present. Elevated levels of serum creatinine as well as mild interstitial changes did develop, however, 12 weeks after daily treatment with CS. Collagen type I transcripts were almost normal after 12 weeks, whereas levels of type IV mRNA were still elevated. Our findings indicate that increases in transcripts encoding collagens precede a deterioration in renal function and the development of interstitial changes in this murine model of chronic CS nephrotoxicity.

Animals↗
PubMed1992

Angiotensin II-induced proliferation of cultured murine mesangial cells: inhibitory role of atrial natriuretic peptide.

Angiotensin II (ANG II), as a single factor, induces proliferation in a cultured murine mesangial cell line (MMC). This study was undertaken to evaluate a possible influence of atrial natriuretic peptide (ANP) on this ANG II-induced proliferation. ANP (10(-7) M) for 2 min significantly increased intracellular cGMP levels in MMC. This increase in cGMP was totally abolished when cells were preincubated for 5 min with 10(-7) M ANG II. Stimulation of intracellular cGMP formation by sodium nitroprusside was also decreased in the presence of ANG II. The ANG II-mediated inhibition of ANP-stimulated intracellular cGMP levels was blocked by Dupont 753, suggesting signal transduction through ANG II receptors of the AT1 class. ANP (10(-7) M) for 24 h completely abolished the ANG II-induced proliferation in MMC. However, 10(-7) M ANP had no significant effect on mitogenesis induced by platelet-derived growth factor or epidermal growth factor. Furthermore, ANP reduced the ANG II-stimulated expression of the proliferating cell nuclear antigen, a cofactor of polymerase delta that is active in the S-phase of the cell cycle. The addition of 10(-3) M N-monobutyryl-guanosine 3':5'-cyclic monophosphate or 8-bromo-guanosine 3':5'-cyclic monophosphate also blocked the ANG II-induced proliferation. ANP (10(-7)) M for 24 h had no significant influence on the expression (number and dissociation constant) of ANG II receptors as determined by binding assays. These results suggest that, besides the previously shown vasoconstrictive and vasodilating effects, complex interactions between ANG II and ANP exist that can modulate mesangial cell growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗