Biomedical subjects

C Klein

Publications and source records attributed to C Klein.

At least 325 records · Page 18Linked to original sources

PubMed1990

[Interpretation of the estrogen receptor content of breast cancer].

The biochemical analysis of estrogen receptor (ER) content, using the DCC (dextran-coated charcoal) method, was compared with different plotting methods of the estrogen-receptor immunocytochemical assay (ER-ICA) in 80 primary breast cancers including 9 metastases under routine conditions. It was evident, that the determined content of estrogen receptors depends on the technique of measurement, as well as the microscopic organizations of the individual carcinomas and should be interpreted in respect of their content of stroma and if possible of tumour heterogeneity.

Antibodies, Monoclonal↗

PubMed1990

A rapid posttranslational myristylation of a 68-kD protein in D. discoideum.

Cells incubated with [3H]myristate were shown to rapidly and specifically acylate a 68-kD protein, p68, in a developmentally-regulated manner. The fatty acid incorporated into p68 was identified as myristate, and is linked to the protein via an amide bond, apparently to an NH2-terminal glycine. The acylation of p68 in D. discoideum displays some unusual properties. Unexpectedly, myristylation of p68 is a posttranslational event and occurs in the presence of inhibitors of protein synthesis. Another unusual finding was that although p68 is a stable protein, the acyl moiety is removed with a half time of approximately 15 min.

Acylation↗

PubMed1990

Engineering a heavy atom derivative for the X-ray structure analysis of cyclodextrin glycosyltransferase.

Based on a preliminary structural model of cyclodextrin glycosyltransferase from Bacillus circulans (EC 2.4.1.19), Ser428 and Ser475 of the enzyme were mutated to cysteines in order to produce suitable heavy atom derivatives. Mutant Ser475----Cys could not be expressed as protein. Mutant Ser428----Cys was expressed in Escherichia coli and purified. It crystallized isomorphously and gave rise to a mercury derivative that improved the electron density map. The structural results show that the new mercury-binding site is in a pocket at the protein surface.

Bacillus↗

PubMed1990

Application of the chromogenic reaction to conventional silver staining, the Ag-NOR staining and the silver-intensified immunogold technique.

The principle of the chromogenic reaction and the transformation of "black and white" histochemical staining results or immunohistochemical signals to coloured microscopic images is described. The chromogenic reaction was optimized and is, so far, possible with either cyan-blue or magenta-red reaction products. The application of the chromogenic reaction to conventional silver stain was optimal in the Lendrum staining resulting in red or blue stained reticulin fibres. The Ag-NOR staining of the nucleolus organizing region (NOR) could be transformed by the same reaction to coloured reaction products as well as the silver-intensified immunogold technique in immunocytochemistry.

Arthritis, Rheumatoid↗

PubMed1990

Quantitative determination of alveolar bone density using digital image analysis of microradiographs.

Horizontal 100 microns ground sections of 20 alveolar bone specimens from adult human mandibles obtained from autopsies were prepared for microradiography. Quantitative analysis of bone density of the alveolar cortex was performed using a semiautomatic digital image analysis system (KONTRON). The results demonstrated that bone density was higher in the lingual than in the labial alveolar cortex (p less than 0.05). In addition, the coronal portion of alveolar cortical bone was significantly more porous than the medical and apical ones (p less than 0.05). These variances were primarily due to increased canal size rather than to an increased number of canals. No significant age dependent changes in bone density could be determined.

Adolescent↗

PubMed1989

Omental angiogenic lipid fraction and bone repair. An experimental study in the rat.

A lipid material extracted from the omentum has previously been shown to contain a potent angiogenetic activator (20), capable of creating intense vasoproliferation in traumatized tissues (19). This study was undertaken to analyze the efficacy of local administration of this omental lipid fraction on osseous vascularization and bone repair. An osteoperiosteal segmental femoral defect in the rat was replaced by a demineralized allogenic bone graft exposed to continuous local delivery of omental lipid via an implanted miniosmotic pump. Saline solution delivered in the same way served as a control. Neovascularization and bone formation in the transplant were quantitatively evaluated by means of dynamic radioisotopic bone imaging, radiographic photodensitometry, microangiography, and biomechanical testing. Compared with the control group, the omental lipid angiogenic fraction-treated specimens showed an 80% overall increase (p less than 0.001) in bone density as well as a twofold increase (p less than 0.001) in regional blood perfusion, maximal at 2 weeks following surgery. At 12 weeks, biomechanical testing demonstrated significantly higher union rate (p less than 0.05) and strength (p less than 0.01) in the treated specimens as compared with the controls. These data demonstrate that the omental lipid fraction factor has potent angiogenic properties that enhance bone blood perfusion and bone regeneration.

Absorptiometry, Photon↗

PubMed1989

Immunocytochemical detection of sulphonylated DNA in tissue sections. An alternative to Feulgen staining of DNA.

We report here on a new sensitive and highly specific DNA staining technique which we have called sulpho-DNA staining. DNA staining is based on a sulphonylation reaction of 2'-deoxycytidine or cytidine that takes place in the 6th position of cytosine with ensuing immunodetection of the sulphonylated DNA. The specificity of DNA staining is introduced by the use of an antibody recognizing only modified DNA but not modified RNA, by recourse to an additional acid hydrolysis step which destroys RNA but not DNA. We describe here the optimal conditions for the sulphonylation of DNA using O-methylhydroxylamine and metabisulphite as reactants. The new DNA stain labels all nuclei in either normal human tissue or in tumor cells. For nuclear DNA the staining signal is higher for the sulpho-DNA staining than for the Feulgen staining for nuclear DNA. This new DNA staining technique is suitable for use on tissue sections as well as on cytosmears.

Animals↗

PubMed1989

Dictyostelium erasure mutant HI4 abnormally retains development-specific mRNAs during dedifferentiation.

The Dictyostelium mutant HI4 progresses through morphogenesis normally, but is defective in the reverse program of dedifferentiation. In contrast to dedifferentiating wild-type cells, HI4 cells retain the capacity to rapidly reaggregate well after the "erasure event" employing a nonchemotactic aggregation mechanism involving random collisions and cohesion. They also do not lose contact sites A (gp80) at the prescribed time in the dedifferentiation program. HI4 cells accumulate transcripts of the cysteine protease gene CP2 (formerly referred to as 16G1) and the cohesion glycoprotein gene gp80 at the correct times in the morphogenetic program, but abnormally retain these transcripts at high levels well after the prescribed times at which they are lost in wild-type cells during the reverse program of dedifferentiation. The retention of these mRNAs in HI4 cells after the erasure event is not due to abnormal maintenance of a high level of intracellular cAMP during dedifferentiation. The rapid reduction in the level of gp80 transcript which can be effected by the addition of cAMP prior to the erasure event in wild-type cells is also retained by HI4 cells well after the erasure event. The results suggest that cells possess at least two mechanisms for the reduction of gp80 transcript. One involves the immediate response to cAMP and may function during the forward program of development. The second functions specifically during the reverse program of dedifferentiation. It is this latter, erasure-specific mechanism which is selectively defective in the HI4 variant.

Blotting, Northern↗

PubMed1989

Characterization of a glycosyl-phosphatidylinositol degrading activity in Dictyostelium discoideum membranes.

Antigen 117 is a glycolipid-anchored cell surface protein implicated in cell-cell cohesion of Dictyostelium discoideum amoebae. Previous studies have demonstrated that during cell aggregation some of the protein is released from the cell surface. Here we report the characterization of the enzymatic activity involved in the 117 antigen release. The data indicate that the releasing enzyme is a phosphatidylinositol phospholipase C. The data also indicate that structural features of glycolipid anchors are conserved in a variety of organisms.

Cations, Divalent↗

PubMed1989

Acute transverse myelitis, a possible vascular etiology.

Seven acute transverse myelitis patients are presented, in whom the course of illness suggests a vascular pathogenesis. In the absence of predisposing risk factors for vascular accidents and such systemic symptoms as occur frequently in vasculitic syndromes, association in hypothesized with isolated angiitis of the central nervous system. Combined treatment with corticosteroids and cyclophosphamide is, therefore, suggested for severe cases of acute transverse myelitis, in whom no etiology can be found.

Acute Disease↗

PubMed1989

Secondary amenorrhea in two sisters with hypogonadotropic hypogonadism and progressive cerebellar ataxia.

The association of familial hypogonadism with progressive cerebellar ataxia is only rarely encountered. Both primary hypergonadotropic and secondary hypogonadotropic hypogonadism may appear with cerebellar ataxia. However, many of these patients suffer from a variety of neurological and/or somatic malformations. Females, which are relatively rarely affected, display primary amenorrhea. In this report, two sisters presented with secondary amenorrhea prior to the appearance of progressive cerebellar ataxia and were found to have hypogonadotropic hypogonadism. This unique family displays clinical evidence for the presence of a possible common mechanism responsible for progressive hypothalamic and cerebellar impairment of late onset.

Adult↗

PubMed1989

GDP stimulates the phosphorylation of a 36-kDa membrane protein in Dictyostelium discoideum.

Increasing effort is directed toward elucidating the mechanisms by which guanine nucleotide-binding proteins regulate specific cellular processes. A common feature of this class of proteins is that GTP induces a transition from an inactive to an active conformation. The latter is limited by the hydrolysis of GTP and the coincident production of GDP. Here we provide evidence that guanine nucleotides may regulate biological processes by inducing the phosphorylation of specific proteins. In particular, we report a GDP-dependent phosphorylation of p36, a 36-kDa protein of Dictyostelium discoideum plasma membranes.

Adenine Nucleotides↗

PubMed1989

Re-expression of 117 antigen, a cell surface glycoprotein of aggregating cells, during terminal differentiation of Dictyostelium discoideum prespore cells.

117 antigen is a glycoprotein expressed on the surface of D. discoideum cells at aggregation. It then disappears and is later re-expressed on the surface of a subpopulation of cells at culmination, the terminal differentiation stage (Sadeghi et al. 1987). A cDNA clone was used to show that the appearance of cell surface 117 antigen accurately reflects the expression of the 117 gene as measured by mRNA levels. It was also shown that during multicellular development there is a reciprocal relationship between the levels of 117 mRNA and the mRNA which codes for prespore surface glycoprotein, PsA. Dual parameter flow cytometry was used to demonstrate that the 117 antigen is found on the surface of maturing prespore cells after the PsA glycoprotein disappears, but that it is not found on mature spores. Using three monoclonal antibodies which identify respectively 117 antigen, PsA, and MUD3 antigen (a spore coat glycoprotein--probably Sp96), two new stages of final spore maturation were defined. These results indicate that there is a recapitulation of at least one aggregative cell surface glycoprotein in the prespore subpopulation of cells as they rise up the stalk during final spore development. This raises the possibility that culmination, which involves complex three dimensional morphogenetic movements not unlike those observed during animal embryogenesis, involves components of the two-dimensional pattern seen during aggregation.

Antigens, Differentiation↗

PubMed1989

Expression of tumor necrosis factor-alpha and transforming growth factor-beta 1 in acute liver injury.

Tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta 1 (TGF-beta 1) have a number of in vitro functions that could be important in vivo in acute liver injury and repair. Therefore, we investigated these two cytokines in acute liver damage. Northern blots of RNA isolated from rats sacrificed at various time intervals after a single oral dose of CCl4 revealed that TNF-alpha mRNA levels were elevated within 6 hr of CCl4 administration and returned to control values by 24-32 hr. In contrast, TGF-beta 1 mRNA levels started to rise significantly at 24 hr, peaked at 48 hr, and approached baseline levels by 72 hr. Identical changes in TNF-alpha and TGF-beta 1 mRNA levels were also seen with D-galactosamine-induced hepatotoxicity. Immunohistochemical analysis using a TGF-beta 1 antibody demonstrated increased hepatic staining in CCl4-treated rats, at times corresponding to the increases in TGF-beta 1 gene expression. Therefore, there is a differential expression of these cytokines in acute CCl4 and galactosamine hepatotoxicity with an early rise in TNF-alpha, suggesting that this cytokine may affect inflammation and cell toxicity, while TGF-beta 1 peaks later, when it may regulate hepatocyte proliferation and extracellular matrix repair.

Acute Disease↗

PubMed1989

[Metachronous bronchial neoplasm. 20 cases surgically treated].

The authors present a series of twenty metachronous lung carcinomas operated upon in the Thoracic Surgery Unit of Nancy between 1975 and 1987. These lesions occur after a first lung tumor resected for stade 1 TNM in 19 cases, with a 59 month's mean free interval and they are surgically treated by 14 controlateral lobectomies and 6 completion pneumonectomies. In spite of 4 post-operative deaths, the survival rates reach 51% at 3 years and 32% at 5 years. This study with a review of the literature emphasize the relatively high incidence of metachronous lung carcinomas in the patient resected for a tumor of good pronostic factors, their occurrence after a prolonged interval, the difficulty to prove their primary nature and the justification of a surgical approach because the long-term results are comparable with that of patients operated upon for a single carcinoma.

Adult↗

PubMed1989

Acute intermittent porphyria in pregnancy.

A 27-year-old, previously healthy normotensive woman was admitted for hyperemesis gravidarum and treated with intravenous fluids and metoclopramide. Thereafter, a neuropsychiatric syndrome developed, with acute asymmetrical axonal motor-sensory polyneuropathy and marked anxiety, depression, irritability, and memory and concentration difficulties. Raised porphyrin precursors were found in the patient's urine, but not in her feces. Although the association of acute porphyria and pregnancy is rare, the pregnancy itself, combined with a state of starvation, and the administration of metoclopramide, could have precipitated the acute attack in this case. Thiamine deficiency, Guillain-Barré syndrome, and an obstetric complication producing closely related symptoms were excluded. The drug was stopped and the patient was treated with a high-carbohydrate diet and physiotherapy. A normal infant was delivered spontaneously at term.

Acute Disease↗

PubMed1988

Expression of the c-fgr related transcripts in Epstein-Barr virus-associated malignancies.

The proto-oncogene c-fgr is expressed at high levels in cell lines derived from lymphomas which are infected with Epstein-Barr virus (EBV) (Cheah et al., 1986). mRNA extracted directly from biopsies of EBV-infected tissues was analyzed on Northern blots to determine if c-fgr is expressed during lympho-proliferations induced in vivo by EBV and in nasopharyngeal carcinoma (NPC), the epithelial malignancy associated with the virus. Elevated levels of c-fgr expression were detected in all EBV-positive lympho-proliferations in vivo but not in cell lines established by EBV infection in vitro. This indicates that the induction of the c-fgr proto-oncogene is not an essential component of EBV-induced transformation. Although no c-fgr expression was detected in EBV-positive or -negative epithelial cell lines, the 3.0-kb c-fgr mRNA was detected at low levels in mRNA obtained from NPC biopsy specimens. However, NPC tissue, after passage in nude mice (which eliminates infiltrating lymphoid and myeloid cells) did not contain the 3.0-kb c-fgr mRNA. The absence of expression of c-fgr in the malignant epithelial cells infected with EBV contrasts with the elevated level of the proto-oncogene in EBV-infected lymphoma tissue and cell lines established from lymphomas. This suggests differences in the expression of cellular functions in EBV-induced malignancies of these 2 distinct cell types.

Genes, Viral↗

PubMed1988

Biosynthesis of 117 antigen: a cell cohesion molecule in Dictyostelium discoideum.

117 antigen is involved in the process of intercellular cohesion in Dictyostelium discoideum [Brodie et al., 1983]. The antigen, a 69- and 72-kDa doublet, was found to arise from a 60- and 62-kDa precursor. The mature antigen contains N-linked oligosaccharides that are sulfated and fucosylated [Sadeghi et al., 1987]. These oligosaccharide chains are resistant to endoglycosidase H digestion. 117 antigen also contains a post-translationally added carbohydrate-containing modification(s). Unlike the N-linked oligosaccharide, this carbohydrate moiety is sensitive to periodate oxidation. 117 antigen is developmentally regulated, and the changes in rate of 117 antigen synthesis reflect changes in the cellular levels of its mRNA. 117 mRNA accumulates in starving cells and reaches its maximum when cells become aggregation competent. The mRNA levels then decline, and by the time the slug structure is formed, no 117 mRNA is present. 117 mRNA reaccumulates for a brief period during early culmination and then returns to an undetectable level.

Antigens, Fungal↗