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Biomedical subjects

J Achard

Publications and source records attributed to J Achard.

At least 19 recordsLinked to original sources
PubMed2001

Protection against ischemia: a physiological function of the renin-angiotensin system.

The renin-angiotensin system (RAS) is involved in a complex mechanism that serves to preserve the blood supply to organs so that they can maintain cellular function. Angiotensin II exerts this effect, independently of the blood pressure generated, through two time-related events: a fast opening of the reserve collateral circulation and a much slower response of new vessel formation or angiogenesis. This effect is observed in rats with ligation of the abdominal aorta and in gerbils with abrupt or progressive unilateral carotid artery ligation. Inhibition of the angiotensin-converting enzyme (ACE) or the angiotensin II receptor represses this effect, and it appears that it is mediated through a non-AT1 receptor site of angiotensin II. Many tumors, both benign and malignant, express renin and angiotensin. It seems that the stimulating action of angiotensin II on angiogenesis could also be involved in preserving the blood supply to tumor cells. Administration of converting enzyme inhibitors increases survival and decreases tumor size in tumor-bearing rats. These observations support the hypothesis that the RAS, directly or indirectly, is involved in situations in which the restoration of blood supply is critical for the viability of cells and that it is present not only in normal but also in pathological conditions such as tumors. In view of the ubiquitous presence of renins and angiotensins, it is also likely to be involved in other conditions, such as inflammation, arthritis, diabetic retinopathy, and retrolental fibroplasia, among others in which angiogenesis is prominent. In addition, angiotensin II could be involved, through the counterbalance of the AT1 and AT2 receptors, in the rarefaction of blood vessels as an etiologic component of essential hypertension.

Angiogenesis Inducing Agents↗
PubMed2001

[Cat scratch disease. Clinical study of 26 patients. Role and importance of PCR].

PURPOSE: Cat scratch disease is a mild pathology but diagnosis often remain difficult. METHODS: A retrospective study has been conducted by the department of infectious diseases at the University hospital in Angers. Between January 1994 and October 1998, 26 observations were recorded providing the presence of three criteria out of four among the following: contact with a cat, clinical presentation and its favorable course, absence of any other cause noticed, and the presence of either a positive serology or a positive PCR, or the examination of a suggestive pathology. RESULTS: Fourteen men and 12 women were concerned. From a clinical point of view, the inoculation lesion was observed six times, all patients showed at least one adenopathy during their illness, 12 patients showed only an adenopathy without clinical signs. A surgical biopsy was carried out on nine patients and a diagnosis established. Bartonella henselae serology was done in all patients. Six presented a significant rate of IgG antibodies as early as the first dosage. A seroconversion was observed in four cases belatedly 1 to 2 months after the beginning of the symptomatology. The method's sensitivity was approximately 38%. A PCR search was accomplished in the pus obtained from a ganglionic puncture on 12 patients. It was positive seven times, which corresponds to a sensitivity of about 58%. In associating these two diagnostic criteria a sensitivity rate of nearly 92% was reached, the diagnosis not having been confirmed only in one case. The outcome proved to be favorable in all cases, with or without an antibiotic treatment. CONCLUSION: The association of serology and PCR in the pus permits a certain diagnosis in the majority of the cases and avoids the more aggressive biopsy.

Adolescent↗
PubMed1998

The dependency of calcium set point on basal plasma calcium in dialysis patients: a better explanation for the discrepancies regarding its link with PTH secretion than methodological differences.

BACKGROUND: The increase of calcium (Ca) set point in uremic hyperparathyroid patients and its decrease with calcitriol therapy are controversial. Besides methodological differences regarding the experimental protocol for obtaining the sigmoidal curve, mainly differences in definitions of maximal PTH (peak or steady value) and of calcium set point itself have been proposed for the discrepant conclusions. However, two other explanations are possible: the various aluminum load of the patients and the dependency of Ca set point upon the basal plasma ionized calcium (PCa). PATIENTS AND METHODS: Therefore the Ca set point was measured in 2 groups of patients on maintenance dialysis never exposed to aluminum, one of 7 patients with normosecretion of PTH (NPT) and the other of 8 patients with hyperparathyroidism (HPT) before and after 3 intravenous administration of 4 microg of alfacalcidol in a week. The sigmoidal curve was established during a zero Ca dialysis, without Ca replacement for the first 90 minutes and with intravenous infusion of 41 mmoles of Ca during the 150 last minutes. The curvilinear decrease of PCa induced a peak of PTH followed by a decrease while PCa was still decreasing up to the 90th minute. Therefore PTHmax was taken both at the peak and at its lower value observed at the 90th minute (steady PTHmax). Experimental determinations of the Ca set point were made using both definitions of Brown and Felsenfeld and both PTHmax values. In basal conditions, while using any of the values given by the same calculation methodology, Ca set point was not different in NPT and HPT patients. After alfacalcidol, no change in plasma PTH nor in Ca set point was observed in HPT patients. In contrast, in NPT patients alfacalcidol induced a significant decrease of plasma PTH concentrations in association with an increase in basal PCa and in Ca set point, whatever the definitions of the latter and of PTHmax. Calcitriol induced changes in Ca set point and basal PCa were correlated. CONCLUSIONS: 1) In normocalcemic dialysis patients never exposed to aluminium hyperparathyroidism is not explained by an increased Ca set point 2) Calcitriol suppressive effect on PTH secretion is neither explained by a decrease in Ca set point. 3) Ca set point as measured in vivo does not reflect an intrinsic characteristic of the parathyroid glands since it varies with basal PCa. Better than methodological differences, this dependency may explain the discrepant conclusions between the various clinical investigations.

Aluminum↗
PubMed1994

Epidemiologic approach to human toxocariasis in western France.

Toxocara canis is a common parasite in puppies. The danger to human health has not been properly established. We estimated the current incidence of this pathogen in two western districts of France, Loire-Atlantique and Maine et Loire. Blood samples from 1836 eosino-philic patients were collected and tested by an enzyme-linked immunosorbent assay (ELISA) excretory-secretory Toxocara antigen test. We obtained positive results in 22% of the cases and highly positive results in 7%. The ELISA data seemed to be age-dependent, with older patients having more positive results (P < 0.0001). The interlaboratory distribution of positive test results was statistically significantly different (P < 0.0001), suggesting regional sources. The main clinical expressions of toxocariasis were: asthenia, gastric pain, and pulmonary disease. Individual and collective surveys of this zoonotic disease need to be carried out.

Animals↗
PubMed1993

[Echocardiographic abnormalities in the stage IV of HIV infection].

Fifty patients in stage IV of HIV infection (including 41 AIDS patients) were prospectively studied by echocardiography. Thirteen of them showed abnormalities: 4 had pericardial effusion, 1 endocarditis, 7 myocardial disorders and 1 primary pulmonary arterial hypertension. Pericardial effusion, also present in patients who had pleuropulmonary Kaposi's sarcoma, was not specific. Myocardial disorders concerned the diastolic function in 1 case, the segmental kinetics in 2 cases and the whole systolic function in 4 cases (3 had congestive myocardiopathy and 1 had transient systole alteration without left ventricular dilatation). The mechanism of global left ventricular disorders was multifactorial, and several hypotheses were discussed: infectious myocarditis, adrenergic or nutritional deficiency myocarditis, cardiotoxicity of antiviral drugs, common pathology with HIV encephalopathy. The prognosis of congestive myocardiopathy was poor in AIDS patients and undetermined in stage IV non-AIDS patients. Echocardiography is capable of detecting these lesions, and its use may contribute to a better care of these patients.

Acquired Immunodeficiency Syndrome↗
PubMed1987

[Neuromeningeal listeriosis in adults, excluding pregnancy. Prognosis and development of neurologic manifestations. Retrospective study of 63 cases].

Patients' constitutional background, treatment and neurological manifestations were analyzed in a retrospective study of 63 cases of neuromeningeal listeriosis in adults. Age over 60 and coma at the onset were of poor prognosis, but immunodepression (present in only 38% of the cases) did not seem to affect the outcome. The ampicillin-aminoglycoside combination did not appear to improve the vital and functional prognoses more than ampicillin alone. The neurological manifestations observed at the end of hospitalization in 16 of the 42 patients who were cured were not necessarily permanent: among the 13 patients who could be followed up for a mean period of 6.5 years, 5 recovered completely, 5 recovered partially and 3 remained unchanged at neurological examination.

Adult↗
PubMedDate not supplied

[Nine-year study of home assisted ventilation in cases of severe respiratory handicap (author's transl)].

When other treatments fail, the prognosis of some chronic respiratory insufficient patients with frequently occurring failures improved when a tracheostomy canula was installed and connected to a respiratory for several hours a day. The even partial correction of blood gas disorders avoids a relapse in right cardiac failure and enables home care of the patient who can resume formerly abandonned activities. Home assisted ventilation greatly modifies the somatic and psychological condition of the patient and requires excellent cooperation by the family and strict technical supervision, at the risk of failure.

Adult↗