PubMed Health⌕ Search

Biomedical subjects

C Stock

Publications and source records attributed to C Stock.

At least 19 recordsLinked to original sources
PubMed1992

Ewing's tumor X mouse hybrids expressing the MIC2 antigen: analyses using fluorescence CDD-banding and non-isotopic ISH.

We present a highly sensitive method that has been applied to map the chromosomal origin of the prominent cell surface antigen of Ewing's tumor cells recognized by monoclonal antibody HBA-71. The technique allows an unambiguous identification of human chromosomal material in interspecific cell hybrids. This is achieved by fluorescent in situ hybridization of biotinylated total human DNA, followed by high resolution fluorescence banding with the chromomycin/distamycin/DAPI triple stain. An advantage of this method is that all signals can be visualized in one single operation by simply switching the appropriate filter blocks. The protocol has proved extremely useful in gene mapping by means of interspecific cell hybrids, a technique that depends on the accurate and unambiguous recognition of the relevant (e.g., human) genetic material in the clonal genome. Our studies confirm that this antigen is the product of the MIC2 gene, which is so far the only well-studied pseudoautosomal gene in man, and which is located on the short arms of chromosomes X and Y. Furthermore, no influence of the Ewing's tumor-specific translocation t(11;22) on MIC2 expression could be discerned.

Animals↗
PubMed1991

Analysis of unstable RNA transcripts of insecticidal crystal protein genes of Bacillus thuringiensis in transgenic plants and electroporated protoplasts.

We have examined expression of several insecticidal crystal protein (ICP) genes of Bacillus thuringiensis in transgenic tobacco plants and electroporated carrot protoplasts. We determined that low levels of lepidopteran toxin cryIA(b) ICP gene expression in plants and electroporated carrot cells is due to RNA instability. We used a series of 3' deleted by cryIA(b) constructs directed by the cauliflower mosaic virus 35S promoter to demonstrate that this instability is minimally contained in the first 579 bases of the gene in both systems. This instability may result from 5'----3' as well as 3'----5' RNA metabolism. The coleopteran toxic cryIIIA gene was also examined in electroporated carrot cells, and found to be poorly expressed. A model for improvement of ICP RNA stability in plants is presented.

Bacillus thuringiensis↗
PubMed1991

Nasal resonometer: an instrument for the assessment and treatment of hypernasality.

We describe an instrument which enables the measurement of the ratio of nasal to oral sound pressures to be made during normal speech. The technique incorporates a novel phase locking technique which effectively discriminates the spectral characteristic of resonant peaks occurring during nasalized speech from other nasal emissions. The results enable an assessment of the degree of resonance in real time, the trend of diagnostic measurements within a treatment session and the success achieved in reaching targets set during treatment.

Adolescent↗
PubMed1990

Immune response in patients with amoebiasis: evaluation of IgG-subclasses.

In order to evaluate the immune response with respect to IgG-subclasses (IgG1-IgG4) in patients with extraintestinal amoebiasis, an ELISA technique was established. It was the aim of this pilot study to quantify the IgG subclass response and to compare the resulting pattern with other systemic protozoal infections. Our results give evidence that IgG4 contributes to more than one third of the total immune response, followed by IgG2, IgG3 and IgG1. Regarding the IgG4 response in patients with Plasmodium falciparum malaria or Chagas disease, IgG4 plays only a minor role in these systemic protozoal infections. The interpretation of a prognostic value of the high IgG4 titres in our patients is not possible at present. However, in patients with a prolonged clinical course of extraintestinal amoebiasis, extremely high IgG4 titres were observed.

Amebiasis↗
PubMed1982

Effect of small bowel bypass on the rat exocrine pancreas.

Biochemical, structural, and functional studies of the exocrine pancreas were performed in adult male Wistar rats over a 3-month period following a 90 per cent jejunoileal bypass or sham operation. The wet weight of the gland, its content in total protein and DNA, as well as its structural organization were similar in both groups. The enzyme content was globally reduced after bypass surgery. However, amylase was much more and earlier affected than lipase and chymotrypsinogen. In addition, zymogen granules diminished in size while lipid droplets deposited in acinar cells. Enzyme secretion stimulated or not by increasing concentrations of caerulein in vitro was generally reduced after intestinal bypass and approximately parallel to the depressed amount of enzymes in the pancreas. These findings suggest that jejunoileal bypass does not modify the size of the rat pancreas despite protein deficiency, but its enzymatic composition and secretory function is altered.

Amylases↗
PubMed1981

Ultrastructural changes in the rat exocrine pancreas after jejunoileal bypass.

The influence of a 90% jejunoileal bypass on the rat exocrine pancreas was studied by morphometrical procedures. In sham-operated animals exocrine acinar cells accounted for 80.3% of the pancreas volume. These cells are composed of 9.9% nuclei, 8.4% mitochondria, 12.2% zymogen granules, 0.3% lipid droplets and 69.2% of a compartment ("ERGLS") composed of endoplasmic reticulum, ribosomes, Golgi areas, lysosomes and the cytoplasmic ground substance. Intestinal bypass did not change the volume density of exocrine cells nor that of nuclei in the cells during the three postoperative months. The means nuclear diameter was approximately the same in both groups. However, the volume density of secretory granules diminished by 50%. This was accompanied by a decrease in mean granular diameter, but not in their numerical density. The volume density of lipid droplets increased 10 fold, that of mitochondria increased slightly from the 15th postoperative day but significantly from the 45th day. The remaining cellular compartment composed of "ERGLS" was not modified by intestinal bypass. These findings suggest that a 90% jejunoileal bypass induces major changes in the composition of pancreatic acinar cells but not in their size.

Animals↗
PubMed1978

Pancreatic acinar cell changes induced by caerulein, vinblastine, deuterium oxide, and cytochalasin B in vitro.

The effects of caerulein, vinblastine (VB), deuterium oxide (D2O), and cytochalasin B upon both the structure and the function of the pancreatic acinar cell were studied in vitro using rat pancreatic fragments. Caerulein (10 ng. per ml.) stimulates the release of enzymes and induces the appearance of numerous exocytotic images at the apical part of the acinar cell. Whereas VB (5.10(-5) M) and D2O (55 per cent) inhibit the secretory response to caerulein, they do not affect the general ultrastructure of the acinar cell. Prolonged incubation in the presence of VB provoked the disappearance of microtubles and the massive precipiation of microcrystalline material in all parts of the cytoplasmic space. Numerous microtubules were found in the acinar cell after exposure to D2O. Although VB and D2O do not alter the microfilamentous network localized at the apical part of the cell, cytochalasin B (2.10(-5) M) disrupts it. This drug decreases the number of microvilli projecting into the enlarged acinar lumen. Whether cytochalasin B is used alone or in association with VB or D2O, it inhibits the secretory response to caerulein and prevents the process of exocytosis. Thus, it is suggested that microfilaments act on a later step of the secretory cycle, i.e., exocytosis, than microtubules. The probable site of action of these latter organelles in the migration of zymogen granules toward the acinar lumen is discussed.

Animals↗
PubMed1977

On the secretagogue effect of dibutyryl cyclic AMP in the rat exocrine pancreas.

DbcAMP greater than or equal to 0.1 mM induces the discharge of exportable enzymes from rat pancreas fragments incubated in vitro. This effect is qualitatively similar to the action of physiological secretagogues acting via hormone receptors: 1) it is accompanied by the appearance of exocytotic images at the acinar cell apex; 2) it is energy dependent but energy supply is low while that required for the carbamylcholine or caerulein response is high and can only be afforded by oxidative phosphorylation; 3) it is calcium dependent, but no alteration of inward or outward calcium movement can be observed; 4) it is altered by agents known to disrupt the microfilamentous microtubular system [41]. However, the secretory response to DbcAMP is quantitatively less than that obtained with hormonal stimuli. A damaging effect of DbcAMP on pancreatic acinar cells is ruled out on histological and biochemical grounds: there is no significant leakage of LDH; protein synthesis, 2-deoxy-D-glucose and L-leucine uptake are unaltered. The secretagogue effect of DbcAMP is reversible, dose-related and specific. It is not mediated by neurotransmitter release or by interaction with their receptors. The evidence presented points to a direct interaction of DbcAMP on the pancreatic acinar cell and suggests the last step of the secretory cycle as the most probable site of action of the nucleotide derivative.

Adrenergic Agonists↗
PubMed1977

Effect of vinblastine on pancreatic enzymes secretion induced by cyclic nucleotide derivatives.

Vinblastine did not affect the basal secretion of enzymes from the rat pancreas, but it potentiates the secretory response to dibutyryl cyclic AMP. This potentiation is confirmed by the observation of numerous pictures of exocytosis at the apical part of the acinar cell. Dibutyryl cyclic GMP by itself, or associated with vinblastine, failed to modify the spontaneous release of enzymes or the secretion induced by dibutyryl cyclic AMP.

Amylases↗
PubMed1976

[Double-blind study for the prevention of postoperative thrombosis].

In a double-blind study a randomized group of 96 patients with abdominal operations received a placebo, dipyridamol/acetylsalicylic acid or ASA alone. Thrombi were verified by the 125-I-fibrinogen test. In 38% of the placebo group deep venous thrombosis (DVT) was found, while only 10% of the dipyridamol/ASA group (P less than 0,05) and 28% of the ASA treated patients (not significant) showed radioactive thrombi. DVT were localized in 83.8% in the calf region. 48.6% of increasend activities were registered up to the end of the first postoperative day, 78.3% up to the third day. The results emphasize the importance of a general antithrombotic prophylaxis. Dipyridamol/ASA seems to be efficient in this regard for abdominal procedures.

Abdomen↗
PubMed1975

Microfilamentous system and secretion of enzyme in the exocrine pancreas. Effect of cytochalasin B.

The microfilaments in the acinar cell of the exocrine pancreas are essentially located in the apical part of the cell: thin microfilaments (50 A), cytochalasin B (CB)-sensitive, form the axis of the microvilli and a network lying beneath the apical membrane; thicker filaments (100 A), at least partly CB-insensitive, form bundles parallel to the plasma cell membrane and the desmosomal links. CB interaction with the acinar cell of the exocrine pancreas involves at least two sites: a membrane site involved in the inhibitory effect of CB on the monosaccharide transport and a less sensitive site at the filamentous level at least partly responsible for the inhibitory effect of CB in the secretion of the exportable enzyme from the pancreatic cell. CB did not alter the energy balance of the acinar cell nor the exchanges of 15-Ca between the extracellular medium and the pancreatic tissue. CB (2 times 10-minus 7 and 2 times 10-minus 6 M) has secretagogue properties whereas CB (2 times 10-minus 5 M) has inhibitory effect on stimulated secretion and secretagogue properties. The mechanism of these secretory effects is not yet explained. The analysis presented in this investigation affords strong evidence for the involvement of the microfilamentous network in the last steps of the secretory cycle in the acinar cell of the exocrine pancreas.

Adenosine Triphosphate↗