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Biomedical subjects

D Simon

Publications and source records attributed to D Simon.

At least 397 records · Page 22Linked to original sources
PubMed1984

Antidiuretic hormone response to osmotic stimulus under fentanyl anaesthesia.

The effect of fentanyl anaesthesia on the plasma antidiuretic hormone (ADH) response to osmotic stimulus was studied in eight patients. Eight g (137 mmol) NaCl were rapidly injected intravenously the day before anaesthesia and blood samples were collected 5, 10, 20 and 30 min after the injection. This protocol was repeated in the same subjects, under anaesthesia with thiopental, nitrous oxide and fentanyl before surgical incision. Plasma ADH markedly increased after NaCl administration and was significantly correlated with plasma sodium (r = 0.67, P less than 0.005) when the patients were awake, whereas it did not change over 30 min and was not correlated with plasma sodium (r = 0.18, P greater than 0.05) under fentanyl anaesthesia. This inhibitory effect of anaesthesia occurred in spite of a significant fall in the mean arterial pressure during the study. In order to eliminate the role of overnight fasting, premedication and fluid load, the same protocol was performed in six control patients who were fasted overnight, premedicated and fluid loaded. These results demonstrate that fentanyl anaesthesia abolishes the plasma ADH response to both osmotic and low arterial pressure stimuli.

Adult↗
PubMed1984

New monoclonal antibodies directed against human renin. Powerful tools for the investigation of the renin system.

Monoclonal antibodies directed against human renin were obtained by the fusing of myeloma cells with spleen cells from Balb/c or high-responder Biozzi mice injected with pure tumoral or highly purified renal renin. These procedures resulted in the production of seven stable monoclonal antibodies to human renin. Antibodies in the hybridoma culture medium were screened by binding to pure iodinated renin or insolubilized renin in a solid phase assay. The concentration of purified antibodies that provided a 50% binding to iodinated renin varied from 1 X 10(-10) to 1 X 10(-7) M. Two monoclonal antibodies were found to be potent inhibitors of renin enzymatic activity in vitro, behaving as noncompetitive inhibitors (Ki, 1 to 4 X 10(-10) M). They were specific for primate renin. Three monoclonal antibodies provided suitable immunoadsorbants for renin purification. One of these immunoadsorbants was used for large-scale purification of the renal enzyme, resulting in an 825-fold renin enrichment in a single step. Two antibodies were able to distinguish between active and inactive renin and enabled concomitant separation and purification of the two enzyme forms in various biological fluids. Monoclonal antibodies also stained human and monkey renal renin when indirect immunofluorescence and peroxidase-antiperoxidase techniques were used. A highly sensitive radioimmunometric assay of renin was constructed with two monoclonal antibodies. The sensitivity of this improved assay should permit the detection of renin in normal human plasma. Monoclonal antibodies have been shown to be superior to polyclonal antibodies in the following areas: the separation of active from inactive renin, the purification of renin from biological fluids, and the setting up of a direct assay of plasma renin.

Amniotic Fluid↗
PubMed1984

[Adrenomyeloneuropathy. Endocrine, clinical and biological study of 4 cases].

Adrenoleukomyeloneuropathy (ALMN) is a rare neurological and endocrine disorder. It usually affects children, and consists of cortical disease and adrenal insufficiency (adrenoleukodystrophy: ALD). An adult form has recently been identified in which medullary disease is associated with an endocrine disorder (adrenomyeloneuropathy AMN). The authors describe the clinical, biological and physiopathological features of four cases of AMN.

Adrenal Insufficiency↗
PubMed1984

Pluripotent embryonal carcinoma clones derived from the human teratocarcinoma cell line Tera-2. Differentiation in vivo and in vitro.

We have derived and characterized single cell clones from a xenograft tumor of the teratocarcinoma cell line Tera-2. Isozyme and chromosomal analyses confirmed their common origin. When cultures of the clones were maintained at a high cell density, many cells exhibited a morphology and cell surface antigen phenotype typical of human embryonal carcinoma cells. These features included a high nucleo-cytoplasmic ratio, prominent nucleoli, and the expression of the globoseries glycolipid antigen SSEA-3. In addition, other cells, in many respects resembling these typical embryonal carcinoma cells, were distinguished by a marked tendency to accumulate cytoplasmic glycogen. Similar cells, together with more differentiated cells, were seen in low passage cultures of Tera-2 itself. When the clones were grown at a low cell density many cells assumed a larger, flatter shape, a few with multiple nucleoli. Also, the fucosylated lactosamine antigen SSEA-1 appeared on some cells, whereas expression of SSEA-3 and HLA-A,B,C tended to be reduced. Often the synthesis of fibronectin was increased. However, no obvious cytoplasmic differentiation was seen upon ultrastructural examination, and synthesis of human chorionic gonadotropin, alpha-fetoprotein, and laminin was not detected. In contrast to the limited spontaneous changes seen in culture, marked differentiation occurred in tumors obtained following injection of the cells into athymic (nu/nu) mice. In additional to embryonal carcinoma cells, these tumors contained a variety of somatic tissues that included glandular structures, possibly related to the primitive gut, and neural elements. These cell lines derived from Tera-2 constitute the first example of clonal human embryonal carcinoma cells, adapted to growth in vitro, that have retained the capacity for differentiation into diverse somatic tissues.

Animals↗
PubMed1983

Towards purification of the scrapie agent.

A method for the partial purification of scrapie infectivity from hamster brain is described. About a 100-1000-fold, 20-fold, and 200-fold enrichment in scrapie infectivity with respect to protein, RNA, and DNA content has been achieved using differential centrifugation, enzyme and detergent treatment. The inbred CLAC strain of hamsters used in our experiments contained about 10 times less infectivity in brain than has been found in randomly bred animals or other inbred strains.

Animals↗
PubMed1983

Brain proteolipids. Isolation, purification and effect on ionic permeability of membranes.

Proteolipid apoproteins have been isolated from a whole bovine brain homogenate by chloroform/methanol extraction, and fractionated by chromatography on modified (lipophilic) Sephadex, followed by ion-exchange chromatography on CM-Trisacryl. The various final, highly hydrophobic, fractions are homogeneous (sodium dodecyl sulfate/polyacrylamide gel electrophoresis). Transmembrane ion transfers were studied by 22Na + flux and electrical conductance measurements. Single channel events were observed at low protein concentrations, in particular with one of the final homogeneous apoproteolipids of molecular mass 24 kDa.

Amino Acids↗
PubMed1983

Male murine embryonal carcinoma cell line selectively metastatic to the ovaries and adrenals.

Developmentally pluripotent embryonal carcinoma cells were isolated from chromosomally male embryo-derived teratocarcinoma and adapted to in vitro growth without a feeder layer. The uncloned original cell line as well as clones derived from it have a tendency to selectively localize to the ovaries and adrenals upon intravenous injection into adult female mice, but only to the adrenals when injected into male mice. The overall take of injected tumor cells was lower in males and the tumors formed slower in males than in females. These findings suggest that the growth of this karyotypically male embryonal carcinoma could be under hormonal regulation.

Adrenal Gland Neoplasms↗
PubMed1983

Complete DNA methylation does not prevent polyoma and simian virus 40 virus early gene expression.

The effect of DNA methylation on polyoma virus and simian virus 40 gene expression was investigated. For this purpose, the cytosines of all C-G dinucleotides of the viral DNAs were methylated by the use of rat liver methylase and the completeness of methylation was verified by dinucleotide analysis and restriction endonuclease treatment. The biological activity of unmethylated and fully methylated DNAs was tested by microinjecting them into tissue culture cells. The functions analyzed included early and late viral gene expression, viral DNA replication, oncogenic transformation efficiency, and virus maturation. No difference in any of these biological functions was observed between methylated and unmethylated DNA. Early gene expression of methylated DNA is not the result of demethylation because viral DNA reextracted from the injected cells, under nonpermissive conditions, retained the methylation pattern of the input DNA. In contrast, viral DNA extracted from transformed cells or from intact virus particles was partially or completely demethylated.

Antigens, Viral, Tumor↗
PubMed1982

Chromosomes of human hepatoma cell lines.

The karyotypes of three human hepatoma cell lines Hep G2, Hep 3B and PLC/PRF/5 were investigated by G- and C-banding techniques. In addition to ploidy changes, typical for most carcinoma cell lines, certain markers were found that remained stable throughout passage of these cultures. Chromosome I is involved in multiple translocations, resulting in at least three copies of the chromosome I heterochromatin region in each cell line. Inversion in the 9qh region is also seen. In addition, each of the cell lines consistently contains trisomy of 17q. The rearrangements of chromosome I are most striking in the Hep 3B and PLC/PRF/5 cell lines, which are derived from human hepatocellular carcinomas and contain integrated copies of the hepatitis B viral genome. These two cell lines are characterized by the presence of at least five copies of the I (p13 leads to q21) region that result from multiple deletions and/or translocations; by consistent trisomy and polymorphism of the 9qh region; and by trisomy of chromosome 10 (also involved in rearrangements). The Hep G2 and Hep 3B cell lines behave functionally as highly differentiated liver parenchymal cells and are karyologically distinguishable from PLC/PRF/5 both by the presence of trisomy of 6 (pter leads to q14) and by the finding that one of the homologues of chromosome 15 is 15q+.

Carcinoma, Hepatocellular↗
PubMed1982

Recent trends in Namibian urbanization.

"The theoretical debates on urbanization and spatial inequalities in development are sketched in relation to the Namibian (South West African) situation. 1951, 1960 and 1970 Population Census data as well as 1976 estimates for urban centres are analysed and interpreted, revealing growth trends in the urban hierarchy and in the three main racial groups in each town."

Africa↗
PubMed1981

Platelet thromboxane production during endotoxin shock.

Circulating thromboxane (TX) is elevated following endotoxin, and platelets become hyperaggregable. Thromboxane synthesis was therefore studied in platelets during endotoxemia. Rabbit blood and platelets were taken at 0, 60 and 120 min after start of E. coli endotoxin infusion (1.10 microgram/kg min, i.v.). Blood incubation with arachidonic acid (AA, 10(-4) M) generated TXA2, which was measured using a superfused rabbit aorta bioassay. Washed platelets were stimulated with 1-14C AA (0.1 microCi) to generate radiolabeled TXB2, which was isolated by TLC and quantitated by scintillation spectrometry. Control (0 time) platelet count was 488 +/- 10(3)/mm3. In the test group, platelet counts fell to 65% of control at 60 min and to 52% at 120 min, while TXA2 generation was 95% (60 min) and 94% (120 min) of control. In contrast a serial dilution of untreated platelets yielded a progressive decline in thromboxane generation. In endotoxemic platelets, the conversion of 1-14C AA to TXB2 (percent/10(9) platelets) was increased at 120 min (0 min, 34.7; 120 min, 40.0: P less than 0.05). Endotoxemic platelets generated greater amounts of thromboxane than did normal platelets, and this condition may account for platelet hyperaggregability in shock.

Animals↗
PubMed1981

Takayasu's aortitis with renovascular hypertension: successful complex revascularization.

We report a case of Takayasu's disease in a young Algerian woman with severe renovascular hypertension that failed to respond to medical treatment. There was a general inflammatory syndrome but no important immunological abnormality. Histology showed non-specific aortoarteritis. A left nephrectomy was done, a monofilament knitted polypropylene prosthesis was placed between the thoracic aorta and the aortic bifurcation, and an aorto-reno-mesenteric graft was inserted. The patient was normotensive with no further therapy 2 years later.

Adult↗