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Biomedical subjects

G Wolf

Publications and source records attributed to G Wolf.

At least 433 records · Page 24Linked to original sources
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↗
PubMed1992

[Nasal cavities and paranasal sinuses in newborns and children].

The paranasal or accessory nasal sinuses begin their development as evaginations of the mucosa during the 3rd and 4th fetal months, but undergo their major expansion after birth according to the development of the facial cranium and the teeth. While in the newborn the sphenoidal and frontal sinuses are still only predispositioned, the ethmoidal labyrinth and particularly the maxillary sinus are of appreciable size. In the 4-year-old the frontal and sphenoidal sinuses are already developed and in the 12-year-old the paranasal sinuses reach their final form and a size equivalent to the adult.

Adult↗
PubMed1992

Angiotensin II stimulates the proliferation and biosynthesis of type I collagen in cultured murine mesangial cells.

A murine mesangial cell line (MMC) was established from the glomeruli of SJL mice to study the influence of angiotensin II (ANG II) on their growth and function in a serum-free culture. Murine mesangial cells exhibit the phenotypic characteristics of mesangial cells, including staining for desmin, vimentin, Thy 1, and types I and IV collagen by immunofluorescence. The addition of daily doses of 10(-6) to 10(-11) mol/l ANG II to MMCs also induced their proliferation in serum-free media. This effect on growth was independent of the presence of insulin in the media, and was receptor mediated, because the specific ANG II-receptor antagonist DuP 753 abolished proliferative growth. Angiotensin II also stimulated mainly the biosynthesis of type I collagen in our MMCs. Transfection of MMCs with chimeric genes containing enhancer/promoter elements for alpha 2(I) and alpha 1(IV) collagens linked to a chloramphenicol acetyltransferase reporter demonstrated that the stimulatory effect of ANG II for type I depends, at least to some extent, on an increase in transcription. These findings indicate collectively that ANG II in serum-free cultures can be a paracrine catalyst for the growth and biosynthesis of type I collagen in mesangial cells.

Angiotensin II↗