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Biomedical subjects

A Chollet

Publications and source records attributed to A Chollet.

47 records · Page 3Linked to original sources
PubMed1985

Sequence determination of the Sendai virus HN gene and its comparison to the influenza virus glycoproteins.

The nucleotide sequence of the Sendai virus (SV) HN (hemagglutinin-neuraminidase) gene was determined. The deduced primary structure of the protein showed only one hydrophobic domain likely to represent the transmembrane region, but at its N terminus. Since the SV F protein is anchored in the membrane at its C terminus, the two SV glycoproteins are thus membrane-anchored in opposite orientations, similar to the two influenza virus (FLU) glycoproteins. Amino acid sequence comparisons of the SV HN and the FLU HA and NA proteins revealed homologies between 100 amino acids of the hemagglutinin region of the FLU HA protein and the C terminus of the SV HN, and between 200 amino acids of the neuraminidase region of the FLU NA and the central region of SV HN. Alignment of the neuraminidase, hemagglutinin, and fusion regions shared by these glycoproteins suggest the structure of a possible ancestral gene.

Amino Acid Sequence↗
PubMed1984

An asanguineous reperfusion solution. An effective adjunct to cardioplegic protection in high-risk valve operations.

The protection afforded by cardioplegia during elective ischemic arrest can be partly compromised by a reperfusion injury, which may impede the recovery of cardiac function. We previously showed experimentally that this postischemic damage could be largely avoided by an appropriate crystalloid reperfusate. The present study was thus undertaken to assess the effects of this "reperfusion solution" clinically. One hundred twelve patients undergoing valve replacement with the aid of hypothermic cardioplegia (K+ 12 mEq, Mg2+ 26 mEq) were prospectively divided in two groups: Group I (n = 49) received an unmodified blood reperfusate. In Group II (n = 63), 1 L of the reperfusion solution was delivered just prior to removal of the aortic clamp. The formulation of the reperfusion solution adhered to the following principles: (1) maintenance of cardioplegia (K+ = 15 mEq), (2) replenishment of Ca2+ stores (Ca2+ = 2.5 mEq), (3) substrate provision (glutamate = 2,942 gm), (4) buffering (pH = 7.70 at 28 degrees C), and (5) hyperosmolarity (370 mOsm). The two groups were matched for preoperative data except for a higher incidence of isolated aortic valve replacement (p = 0.01) in Group II. Also, the cross-clamp time (mean +/- standard error of the mean) was longer in Group II (94 +/- 4 minutes versus 63 +/- 4 minutes, p less than 10(-6]. The reperfusion solution was found to increase both the rate and extent of postischemic functional recovery, as evidenced by (1) a lower proportion of catecholamine-supported patients 48 hours after operation (9/63 [14.28%] versus 16/49 [32.6%] in the control group [p less than 0.03]) and (2) a lower amount (gamma/kg/min) of dobutamine required to achieve stable hemodynamics (11 +/- 1 versus 26 +/- 6 in the control group [p less than 0.03]). A similar recovery pattern was noted in the high-risk subgroup of patients with mitral valve disease. Further, serial postoperative hemodynamic measurements were performed in 31 randomly selected patients (10 control and 21 reperfused). Although the reperfused patients were found to be at higher risk because of lower preoperative cardiac indices and longer cross-clamp times, they consistently achieved better postoperative hemodynamics with a lower incidence of catecholamine support. This hemodynamic improvement was particularly reflected by a higher left ventricular stroke work index throughout the postoperative course, the difference being significant 6 hours and 12 hours postoperatively.(ABSTRACT TRUNCATED AT 400 WORDS)

Catecholamines↗
PubMed1983

Coronary artery spasm during non-cardiac surgical procedure.

A case of coronary artery spasm during a non-cardiac surgical procedure is presented. Two paroxysmal episodes of ST segment elevation in lead 11 and aVF without changes in V5 developed during general anaesthesia. These changes were not preceded by increases in heart rate or arterial pressure. The second episode was associated with a ventricular bigeminal rhythm. This case demonstrates the importance of monitoring several leads in patients likely to develop peroperative spasm of the coronary arteries. Intravenous nitroglycerin was effective in treating the second episode of coronary artery spasm. However, this episode occurred in spite of nitroglycerin administered intravenously at a rate of 0.25 microgram/kg min.

Aorta, Abdominal↗
PubMed1983

[Hypo-oxygenation in paraquat poisoning. Apropos of 6 cases].

The toxicity of the weed-killer paraquat is related to the formation of superoxyde radicals responsible of a progressive and usually lethal pulmonary fibrosis. Recognition of lipid peroxidation of membrane bilayers by free radicals as the causative factor pointed to oxygen as an important cofactor in the severity of paraquat poisoning. It has been shown that any FiO2 over 21% accelerates this process and increases the the mortality of rats and humans. FiO2 21% gave a significant reduction of mortality in rats (DOUZE 1976). We proposed this therapy (1978-1879) in 6 cases of paraquat poisoning. It was conducted with induction of a barbiturate coma, hypothermia, curarisation and hypo-oxygenation (FiO2 around 14% thanks to the adjunction of nitrogen to assisted ventilation). In 5/6 patients, these technics did not prevent the evolution towards death. This evolution was in fact predicted, according the following prognostic factors: suicide, more than a mouthful ingestion, oesophago-gastric burns detected by endoscopy, organic renal failure, high plasma paraquat level. Associated methods of elimination (Fuller's earth, provoked diarrhea, furosemide, hemoperfusion and hemodialysis) did not change the early established prognosis. The only survival was observed in an accidental poisoning with undetectable plasma paraquat and isolated oral burns: the herbicide had been probably spit out. This survival cannot be related to hypo-oxygenation. This failure is not definitive, according to us: this therapy should be undertaken only after minimal, accidental poisoning possibly evolving to pulmonary fibrosis. It appears unuseful in massive, suicidal poisonings, leading readily to a lethal circulatory failure.

Adolescent↗
PubMed1980

[The technique of anesthesia for the prevention and treatment of gaseous embolism in the neurosurgical sitting position (author's transl)].

The sitting position in neurosurgery gives always three problems for the anaesthesist: --maintain the cerebral perfusion pressure, --not to aggravate intracranial hypertension, --detect gaseous embolism. The clinical signs of air embolism often look like the awakening of the patient. That is why it is necessary to use specific methods to detect them: Doppler, Swan-Ganz catheter, and/or continuous CO2 recording of expired air by capnograph. Among the various methods to prevent air embolism we have used controlled respiration with a positive and expiratory pressure (P.E.E.P.). In our series (45 operations) gas embolism occurred in 13% of the patients operated upon without positive and expiratory pressure, and 0% with P.E.E.P.

Anesthesiology↗
PubMed1977

[Treatment of essential facial neuralgia by selective thermocoagulation of Gasser's ganglion].

The authors report their experience in the treatment of essential facial neuralgia by differential thermocoagulation of the gasserian ganglion. This method is based upon the fact that small pain fibres (A delta and C) are more sensitive to warmth than large touch fibres. Thus progressive and controlled thermocoagulation of the trigeminal ganglion makes it possible to obtain selective destruction of the small fibres (analgesia without anaesthesia). 76 patients were treated using the method, and in 75 cases the symptoms of neuralgia disappeared immediately. Mortality is nil and morbidity insignificant other than the effects on the trigeminal nerve. The most serious complication (Approximately 10% of cases) was that of marked hypoaesthesia, rather than pure analgesia, in the coagulated area.

Adult↗
PubMedDate not supplied

High-level expression of G protein-coupled receptors with the aid of the Semliki Forest virus expression system.

The expression of two G protein-coupled receptors was studied in several cell lines using the Semliki Forest virus expression system. Human neurokinin-2 and dopamine D3 receptor cDNAs were introduced into the pSFV1 vector. In vitro transcribed RNAs were coelectroporated with pSFV-Helper RNA into BHK cells resulting in in vivo packaging of high titer SFV-NK-2 and SFV-D3 virus stocks, respectively. Infection of BHK, HOS and CHO cells with the recombinant NK-2 virus resulted in high levels of receptor expression as detected by metabolic labelling with [35S]-methionine. The expression of the NK-2 receptors in the cell membrane was demonstrated by Flow cytometry experiments on infected BHK and CHO cells with fluoresceinyl-NKA as the ligand. Saturation binding assays on membranes prepared from SFV-NK-2 infected CHO cells with [3H] GR100679 showed maximum receptor densities of 6.5 pmol receptor/mg protein. Additionally, the expressed NK-2 receptors were able to stimulate Ca2+ mobilization in CHO cells indicating functional coupling to G proteins. CHO cells infected with SFV-D3 also produced high levels of receptor as evidenced by both [35S]methionine labelling and [3H]spiperone binding.

Animals↗