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Biomedical subjects

C Perret

Publications and source records attributed to C Perret.

305 records · Page 17Linked to original sources
PubMedDate not supplied

Reported family aggregation of pancreatic cancer within a population-based case-control study in the Francophone community in Montreal, Canada.

As part of the SEARCH Collaborating Study Group of the International Agency for Research on Cancer (IARC), a population-based case-control study of cancer of the pancreas was conducted in Montreal, interviewing 179 patients and 179 controls matched for age, sex, and language (French) and selected by a modified random-digit dialing method. Results showed a positive and strong association between cigaret smoking and pancreatic cancer. Total fat, particularly saturated fat, and cholesterol consumption and excess energy derived from fat were associated with positive risk; dietary fiber intake, retinol equivalent, beta-carotene, vitamin C, and calcium showed inverse association with risk. History of such medical conditions as constipation, gallbladder problems, and diabetes was also found to be associated with risk. More important, 7.8% of the pancreatic cancer patients reported a positive family history of the same disease, as compared with 0.6% among controls, a 13-fold difference between cases and controls. Within the original case-control study a further study of patients with instances of familial pancreatic cancer was conducted, based on 14 cases and 56 matched controls. The results support the finding of the main study, and there were no apparent differences in environmental-risk-factor profile in familial and nonfamilial cases. This unusual aggregation of familial pancreatic cancer among French Canadians cannot be explained by environmental factors alone. Some familial predisposition (hereditary factors) may play an important role in the etiology of this cancer, at least in this study region. The findings suggest the potential importance of conducting genetic studies of pancreatic cancer.

Canada↗
PubMedDate not supplied

Comparison between ventral spinocerebellar and rubrospinal activities during locomotion in the cat.

During fictive locomotion of the thalamic cat, rhythmic activity related to the efferent discharges in hindlimb nerves was found in rubrospinal neurons (Arshavsky et al., this issue). Since the movements were abolished by curarization, this modulation could not result from rhythmic peripheral inputs and had therefore a central origin. Taking into account the existence of spinal generators, it was suggested that ascending pathways transmit rhythmic activity from these spinal centers to the supraspinal ones. Preliminary results have been obtained for neurons of the ventral spinocerebellar tract (VSCT) recorded during fictive locomotion: (1) their discharge is rhythmically modulated at the periodicity of the locomotor rhythm; (2) their discharge pattern can be complex and variable in relation with the complexity and variability of the pattern of efferent activity in various muscle nerves of the ipsilateral hindlimb; (3) their responses to phasic afferent stimulation of the ipsilateral hindlimb are modulated in parallel with their locomotor-related activity. These results show that VSCT neurons convey information on the central spinal activity during locomotion, and suggest that these neurons contribute to the activity of lumbar-projecting rubrospinal neurons which have similar characteristics.

Afferent Pathways↗
PubMedDate not supplied

Activity of rubrospinal neurons during locomotion and scratching in the cat.

It is now well established that locomotion and scratching in vertebrates can result from the activation of a spinal central generator. The possibility of control of these rhythmic motor activities by the red nucleus has been analyzed in the thalamic cat, in which efferent nerve discharges representing fictive locomotion or fictive scratching can still be recorded following paralysis by curarization. It was found that the discharge of lumbar-projecting rubrospinal neurons is modulated in relation to the intensity and frequency of the rhythmic efferent activity in the contralateral hindlimb. The average firing frequency was minimal at the transition between the extensor and flexor efferent bursts and increased progressively to reach a maximum in the second part of the flexor burst. Comparison of the rubrospinal activities during real and fictive rhythmic motor activities revealed only minor influences of phasic afferent inputs. Analysis of the relations between the rhythmic discharges found in rubrospinal neurons, cerebellar neurons (interpositus nucleus and paravermal Purkinje cells of the cerebellar anterior lobe) and neurons of an ascending pathway (ventral spinocerebellar tract) leads to the conclusion that the rubrospinal tract belongs to an internal loop between spinal and supraspinal centres. However, until now, the results do not allow the evaluation of its contribution to the motor performance, even in situations which, like those studied here, do not involve the complex motor control present in the intact cat.

Animals↗
PubMedDate not supplied

Vitamin-D dependent 9 kDa calcium-binding protein gene: cDNA cloning, mRNA distribution and regulation.

Cholecalciferol (calcitriol) the active hormonal form of vitamin D induces the synthesis of at least two intracellular calcium-binding proteins (Ka = 10(6) M-1), the cholecalcins (CaBP) in mammals. We used the synthesis of these proteins to study the genomic steroid-like action of vitamin D. The 9 kDa CaBP is mainly concentrated in the duodenum while 28 kDa CaBP is located in the kidney and cerebellum. Complementary DNA copies of rat intestinal 9 kDa CaBP mRNA were cloned in E. coli. The deduced amino acid sequence for 9 kDa CaBP contains two 'EF hand' domains corresponding to calcium-binding sites I and II. The homology observed suggests, after comparison with the structures of other intracellular CaBPs, that rat 9 kDa CaBP mRNA contains the remains of an untranslated calcium-binding site III-like structure seen in 28 kDa CaBP from kidney and cerebellum of rat. Northern blots showed that the cDNA sequence hybridizes to a homogeneous 500-600 nucleotide mRNA species from rat duodenum. Larger mRNA species encoding 28 kDa CaBP were undetectable in rat kidney and cerebellum even under low stringency conditions. These findings demonstrate that there is no cross-hybridization between 9 kDa and 28 kDa CaBP mRNAs, and Southern analysis indicates that there are distinct genes coding for each rat cholecalcin. The cDNA probe was used to analyze the specific 9 kDa CaBP gene expression along the intestine of growing rats and during gestation and fetal development.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Acid-base response to chronic hypocapnia in man.

The acid-base values of 13 patients with stable carbon dioxide tensions under controlled ventilation have been used to define the response to chronic hypocapnia in man. These patients had a respiratory paralysis and no apparent complicating disorders. Over a range of carbon dioxide tensions from 24 to 40 millimetres of mercury, the arterial blood hydrogen ion concentration decreased linearly by 0.32 nanomole per litre per millimetre of mercury decrement in carbon dioxide tension. Of primary interest was the finding that the slope of the regression line in chronic hypocapnia is close to that already reported for chronic hypercapnia. The physiological response to chronic hypocapnia in man is defined by a band that is approximately 10 nanomoles per litre (0.09 pH unit) wide for hydrogen ion concentration and 6 millimoles per litre wide for bicarbonate concentration. These significance bands may be used to differentiate additional acid-base disorders in patients with chronic hypocapnia over a clinically useful range of carbon dioxide tensions.

Acid-Base Imbalance↗
PubMedDate not supplied

[Irradiation of the rabbit ciliary body by an accelerated proton beam].

Rabbit ciliary body has been irradiated by accelerated proton beam. 24 animals have received on 20 and 40% of the total surface of ciliary body 45 and 60 Gy. We could confirm the very good precision of proton beam irradiation. No complication was noticed on slit lamp examination. The light microscope examination revealed haemorrhages, lymphocytes, plasma cells and histiocytes infiltration, late fibrosis and severe capillary alterations. The electron microscope examination showed a frank difference of radiosensitivity of the epithelial layers and a presumed partial rupture of the blood-aqueous barrier.

Animals↗
PubMedDate not supplied

[Oxygen transport in shock (author's transl)].

This review considers functional repercussions of shock state on the different stages of oxygen transport from alveolus to mitochondria. At the pulmonary level, the decrease in perfusion pressure induces disturbances in the distribition of VA/Q ratio, and therefore leads to aerial hypoxaemia. Prolonged ischemia injures the air-blood barrier and reduces the area of exchange. Decrease in oxygen delivery to the tissue is related to a fall in cardiac output (hemorrhagic and cardiogenic shock) or to a primary disturbance in peripheral circulatory distribution (septic shock) or to a primary disturbance in peripheral circulatory distribution (septic shock). The intervention of compensating factors leads to a redistribution of the regional perfusion and probably to an easier oxygen delivery by haemoglobin. However circulatory inhomogeneity by itself produces a progressive deterioration of microcirculation. Decrease in intracapillary circulation. Decrease in intracapillary circulation and impairment in blood rheologic properties contribute to aggregates formation and intravascular coagulation. The result is a decrease in capillary diffusion capacity and in oxygen intracellular transport. When intracellular PO2 reaches a critical level, the functional exclusion of mitochondria involves a metabolic shift to anaerobiosis. The value of hyperlactacidemia as a sign of oxygen debt is discussed.

Blood Pressure↗