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Biomedical subjects

C Roche

Publications and source records attributed to C Roche.

At least 73 records · Page 4Linked to original sources
PubMed1994

Optic gliomas in neurofibromatosis type 1 (NF-1). Presentation of 31 cases.

We present a series of 31 cases of optic glioma associated with neurofibromatosis type 1 in patients under 11 years of age. They represent 64% of all the optic gliomas seen in our service between September 1965 and September 1993. The optic nerves were affected in 25 cases (83%); 9 children (30%) had a isolated, unilateral tumor; 16 (53%) had involvement of the optic chiasm as well as of one or both optic nerves. In 6 cases (19%) only the chiasm was affected, with or without involvement of other intracerebral structures. A coincidental orbital plexiform neurofibroma was associated with a poor prognosis. Other complications included 8 cases (26%) presenting with slowly developing aqueductal stenosis requiring treatment with a shunt. High-resolution computed-tomographic scans provided well-defined images for the diagnosis of optic nerve glioma, but magnetic resonance imaging was the preferred procedure for the diagnosis of gliomas involving the chiasm and the optic tracts and radiations, particularly if there was no mass effect. In our patients, tumor growth was hardly noticeable during follow-up even up to 20 years, with no difference between patients who were treated with radiation and those who were not treated. However, endocrine disturbances developed in all cases subjected to radiotherapy, and were less frequent in untreated patients. Aqueductal stenosis was observed with similar frequency among both treated or untreated patients. Three patients died, two due to complications of hydrocephalus secondary to aqueductal stenosis and one because of respiratory problems due to compression of the hypothalamus and brainstem by the chiasm tumor. Two of the 3 patients who died had orbital plexiform neurofibroma.

Age Factors↗
PubMed1993

Simultaneous high-performance liquid chromatographic assay of droperidol and flunitrazepam in human plasma. Application to haemodilution blood samples collected during clinical anaesthesia.

A simultaneous assay for droperidol and flunitrazepam by high-performance liquid chromatography has been developed and applied to blood samples collected during an acute normovolemic haemodilution under general anaesthesia. Haemodilution blood samples were stored at +4 degrees C to be transfused, if required, to a patient during the post-surgical phase. A C18 Supelclean cartridge was used for solid-phase extraction, and the recoveries were 74% and 89%, respectively, for droperidol and flunitrazepam. Compounds were chromatographed on a C18 Novapak column at 250 nm, with a mobile phase of acetonitrile-10 mM ammonium acetate buffer (pH 6.7) (45:55, v/v). Nitrazepam was used as the internal standard. For both drugs, the assay was linear up to 500 micrograms/l, and the detection limits were 20 and 10 micrograms/l for droperidol and flunitrazepam, respectively, and their observed levels in haemodilution samples were 93 +/- 82 micrograms/l and 76 +/- 107 micrograms/l, respectively. Some of the values for flunitrazepam were higher than the minimal efficient concentration, defined as the plasma level observed at the time of the patient wakening from anaesthesia (12 +/- 4 micrograms/l). According to our results, haemodilution sampling can be performed before induction of anaesthesia. When the blood is collected after the anaesthetic induction, it seems necessary to determine levels of the two drugs in haemodilution samples to avoid side-effects.

Adolescent↗
PubMed1993

Ultra-rapid, simple, sensitive, and economical silica method for extraction of dengue viral RNA from clinical specimens and mosquitoes by reverse transcriptase-polymerase chain reaction.

A rapid, simple and efficient single-tube procedure is described for the isolation of dengue virus RNA from small amount of serum (10 microliters) followed by a reverse transcriptase-polymerase chain reaction (RT-PCR). Recovery of RNA is based on the lysing and nuclease-inactivating properties of guanidinium thiocyanate in the presence of silica. The silica RT-PCR can be completed within 5 hours starting from RNA extraction to agarose gel electrophoresis. All of the 63 dengue-3 culture-positive sera were RT-PCR-positive (virus titres: < 10(2) to 11(10.69.). Of 33 culture-negative acute sera from serologically confirmed dengue fever patients collected during dengue-3 epidemic, 4 were RT-PCR-positive. RT-PCR was also positive in 29 of 30 dengue-1 culture-positive sera (virus titres range: < 10(2) to 10(8.69). Dengue-1 virus was also detected in field-caught Aedes aegypti mosquitoes by silica RT-PCR.

Aedes↗
PubMed1991

[The amnesic effects of midazolam in premedication of children].

The aim of this study was to check local and general tolerance as well as anxiolytic and amnesic effects of midazolam intramuscular administration as a premedication in 4 to 10 years old children. A double blind, comparative study with a placebo was achieved, after drawing lots, in 40 children divided into two equal groups. Premedication consisted of either midazolam or injectable water administrated with a posology of 0.3 to 0.5 mg.kg-1 combined, in both cases, with atropine sulfate (0.015 mg.kg-1). Results confirmed good local and general tolerance. Also anterograde amnesia was found to be excellent: 17 children in the midazolam group did not remember a photograph shown after premedication, instead of only one in the placebo group. Anxiolytic effects, similar in both groups, cannot be considered owing to the too short interval of time from premedication to induction.

Anxiety↗
PubMed1990

Characterization of muscarinic acetylcholine receptors on the rat pancreatic gastrin-producing cell line B6 RIN.

The mechanisms of cholinergic stimulation of gastrin cells were studied in the rat pancreatic cell line B6 RIN. Carbachol induced an increase in intracellular Ca2+ and stimulated gastrin release in a dose-dependent manner over the range 10(-5)-10(-3) M. These effects were completely abolished by atropine, suggesting the implication of muscarinic cholinergic receptors. The binding properties of these receptors were investigated. [N-Methyl-3H]scopolamine [( 3H]NMS) binding on cell homogenates was time-dependent, saturable and consistent with a single high-affinity binding class (Kd = 39.5 pM, and Bmax = 7.9 fmol/mg DNA). Carbachol competitively inhibited [3H]NMS binding. The potency of inhibition of [3H]NMS binding by subtype selective antagonists was hexahydrodifenidol greater than pirenzepine greater than AF-DX 116. These results suggest the M3 muscarinic receptors may be involved in the carbachol-induced gastrin release from B6 RIN cells.

Animals↗
PubMed1990

[The role of neonatal electroencephalography in the prognosis of the hypoxic-ischemic syndrome].

One hundred and thirty four newborn children of 37 weeks' gestation age or greater, with evidence of hypoxic-ischemic encephalopathy following perinatal asphyxia and surviving through the neonatal period were prospectively studied. The study involved evaluation of clinical outcome and the presence of epilepsy associated with the EEG pattern in the neonatal period. The results prove that the presence of a burst suppression EEG pattern and a hypoactive/flat EEG are negative prognostic criteria. In presence of a focal or multifocal pattern it is difficult to establish a clear prognostic criteria. Last, in newborn children with a normal EEG; with a low amplitude register; with frequencies slow or with bilateral sharp waves transients, a good prognosis can safely be established.

Asphyxia Neonatorum↗
PubMed1989

A rapid mechanical vibration procedure for purifying mature (Ia positive) columnar epithelial cells from the mouse small intestine.

A mechanical vibration method previously described for isolating gut epithelium was adapted to purify murine small intestinal epithelial cells in single cell suspension with high viability, good yield, optimal purity (99% epithelial cells with no other contaminating intestinal cells), and with preservation of phenotypical and physiological properties of epithelial cells. This rapid and easy procedure did not involve the use of any chelating agent or proteolytic enzyme. Extracted gut epithelial cells were suitable for in vitro functional assays within 45 min. Cell viability, as assessed by both the trypan blue due exclusion test and by titration of lactate dehydrogenase activity in the supernatant was greater than 75% up to 7 h after epithelial cell extraction. Light microscopy analysis of the duodeno-jejunal segment before and after mechanical vibration indicated that villous but not crypt epithelium was obtained using this method. Furthermore 99% of isolated epithelial cells expressed major histocompatibility class II (Ia) antigens indicating that the method was suitable for studies of the antigen presenting capacity of gut enterocytes.

Animals↗
PubMed1989

Theophylline inhibits transcellular Ca transport in intestine and Ca binding by CaBP.

Theophylline, when added to the incubation medium of everted duodenal sacs prepared from rats on a low-calcium diet, was found to inhibit transcellular Ca transport in a concentration-dependent manner, with an inhibitor constant (Ki) of 10.8 mM theophylline. Neither the rate of cellular Ca entry, as evaluated with the aid of brush-border membrane vesicles, nor the rate of cellular Ca extrusion, assessed by measuring ATP-dependent Ca uptake of basolateral membrane vesicles, was significantly altered by the addition of theophylline to the uptake media. However, Ca-binding by calcium-binding protein (CaBP; calbindin D9k), Mr approximately 8,800) was depressed by theophylline in a concentration-dependent manner, with Ki = 3.2 mM theophylline. Theophylline had no effect on Ca binding by calmodulin and the theophylline-induced inhibition of transcellular calcium transport was independent of adenosine 3',5'-cyclic monophosphate levels. Theophylline also had no effect on paracellular Ca movement. Since the theophylline-induced inhibition of Ca-binding by CaBP paralleled the inhibition of transcellular Ca transport, it is concluded that CaBP functions in transcellular Ca transport via its ability to bind Ca.

Animals↗
PubMed1986

Localization of vitamin D-dependent active Ca2+ transport in rat duodenum and relation to CaBP.

Vitamin D-replete (+D) and vitamin D-deficient (-D) rats received by intraperitoneal injection varying amounts of 1,25-dihydroxyvitamin D3, and 4 h (+D) or 9 h (-D) later everted duodenal sacs were prepared to evaluate active calcium transport, i.e., the amount of calcium found in the serosal fluid. At the same time, duodenal calcium-binding protein (CaBP) content was measured. Calcium transport was a close positive function of CaBP content. It was not detectable when CaBP content was zero and increased linearly without plateauing as CaBP content increased to 100 nmol calcium bound/g mucosa. Trifluoperazine (TFP) inhibited active calcium transport in a concentration-dependent manner. Experiments using vesicles prepared from brush-border or basolateral membranes indicated that TFP inhibited the calcium-extrusion process, with virtually no effect on calcium entry. It is concluded that vitamin D exerts its major regulation of active calcium transport in the rat duodenum via CaBP on transport steps beyond brush-border entry.

Animals↗
PubMed1985

Distribution of Ca2+-ATPase, ATP-dependent Ca2+-transport, calmodulin and vitamin D-dependent Ca2+-binding protein along the villus-crypt axis in rat duodenum.

The migration of intestinal epithelial cells from the crypts to the tips of villi is associated with progressive cell differentiation. The changes in Ca2+-ATPase activity and ATP-dependent Ca2+-transport rates in basolateral membranes from rat duodenum were measured during migration along the crypt-villus axis. In addition, vitamin D-dependent calcium-binding protein and calmodulin content were measured in homogenates of six cell populations which were sequentially derived from villus tip to crypt base. Alkaline phosphatase activity was highest at the tip of the villus (fraction I) and decreased more than 20-fold towards the crypt base (fraction VI). (Na+ + K+)-ATPase activity also decreased along the villus-crypt axis but in a less pronounced manner than alkaline phosphatase. ATP-dependent Ca2+-transport in basolateral membranes was highest in fraction II (8.2 +/- 0.3 nmol Ca2+/min per mg protein) and decreased slightly towards the villus tip and base (fraction V). The youngest cells in the crypt had the lowest Ca2+-transport activity (0.9 +/- 0.1 nmol Ca2+/min per mg protein). The distribution of high-affinity Ca2+-ATPase activity in basolateral membranes correlated with the distribution of ATP-dependent Ca2+-transport. The activity of Na+/Ca2+ exchange was equal in villus and crypt basolateral membranes. Compared to the ATP-dependent Ca2+-transport system, the Na+/Ca2+ exchanger is of minor importance in villus cells but may play a more significant role in crypt cells. Calcium-binding protein decreased from mid-villus towards the villus base and was undetectable in crypt cells. Calmodulin levels were equal along the villus-crypt axis. It is concluded that vitamin D-dependent calcium absorption takes primarily place in villus cells of rat duodenum.

Alkaline Phosphatase↗
PubMed1985

Comparative effects of vasoactive intestinal peptide and secretin on exocrine pancreatic secretion in the cat.

The stimulatory effect of vasoactive intestinal peptide (VIP) and secretin has been compared on exocrine pancreatic secretion in anaesthetized cats. Both peptides were given by bolus intravenous injection and continuous intravenous infusion. After bolus injection, VIP stimulated pancreatic secretion only weakly. On the contrary, during intravenous infusion, the maximal effect of VIP did not differ significantly from that of secretin. Therefore, while the potency of VIP is always lower than that of secretin, its efficacy appears to be strictly dependent on the mode of administration.

Animals↗
PubMed1985

Infantile calcified cerebral aneurysm.

A case of a calcified aneurysm of the posterior cerebral artery is reported. Frequency, aetiology, pathology, diagnosis and treatment of these aneurysms are discussed.

Calcinosis↗