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Biomedical subjects

J Blanc

Publications and source records attributed to J Blanc.

At least 37 records · Page 2Linked to original sources
PubMed1994

Characterization of a promiscuous GTPase-activating protein that has a Bcr-related domain from Caenorhabditis elegans.

Human breakpoint cluster region (bcr) gene product is a member of a group of GTPase-activating proteins that act exclusively on members of the Ras-related Rho subfamily. A complementary DNA was isolated from Caenorhabditis elegans that encoded a polypeptide of 1438 amino acid residues, CeGAP, which contains a domain with sequence similarity to the COOH-terminal segment (GTPase-activating protein region) of Bcr and other known GTPase-activating proteins of the Rho subfamily. It also contains a "pleckstrin homology" motif, present in many signaling proteins including GTPase-activating proteins and nucleotide exchange factors. The Bcr-like domain of CeGAP exhibited activity not only on members of the C. elegans and human Rho subfamily but surprisingly also on C. elegans Ras protein (let-60), human Ras, and Rab3A. CeGAP is therefore the first GTPase-activating protein acting on Ras-related proteins across different subfamilies. Together with the presence of the pleckstrin homology motif, our finding suggests a central and integrative role for CeGAP in a signaling pathway common to Ras and related proteins.

Amino Acid Sequence↗
PubMed1994

Spectral analysis of blood pressure and heart rate variability in response to stress from air-jet in the Lyon rat.

1. Power spectral analysis of the frequency of wave-forms of blood pressure and heart rate was used to characterize short-term fluctuations of these parameters in three strains of conscious Lyon rat, normotensive (LL and LN) and hypertensive LH. 2. A mild stress produced by means of a jet of air elicited blood pressure rises, associated with tachycardia. This response was of similar magnitude in the three strains. The stressor amplified the medium frequency (195-605 mHz) Mayer waves of blood pressure and heart rate which are under autonomic control. 3. Clonidine (10 micrograms kg-1 i.v.) lowered blood pressure and heart rate and dramatically reduced the amplitude of blood pressure and heart rate oscillations in the frequency region of 195-605 mHz. 4. A jet of air applied after clonidine administration led to blood pressure rise associated with tachycardia and enhanced oscillations in the 195-605 mHz region. 5. These results indicate that in Lyon normotensive and hypertensive rats, a mild emotional stressor elicits blood pressure and heart rate rises associated with spectral modifications reflecting sympathetic hyperactivity. Clonidine lowers blood pressure and heart rate and reduces their related variabilities. This effect is more pronounced in LH rats than in their normotensive controls. Clonidine appears to reduce the autonomic response to stress as indicated by the medium frequency oscillations.

Analysis of Variance↗
PubMed1992

Differential effects of enalapril and hydralazine on short-term variability of blood pressure and heart rate in rats.

Using a spectral procedure, we studied the acute and chronic effects of enalapril and hydralazine on the variability of blood pressure (BP) and heart rate (HR) in conscious Wistar rats. In the acute protocol, rats received two injections 25 min apart (saline followed by enalaprilic acid or hydralazine hydrochloride). In the chronic protocol, animals received oral enalapril maleate, hydralazine hydrochloride, or distilled water. A 5-min recording session was initiated on day 12. Acute enalapril and hydralazine amplified the low-frequency (LF) component of the systolic BP (SBP) spectrum. Chronic enalapril reduced the variability of BP, as indicated by the lower variance in SBP distribution. Chronic enalapril preferentially reduced the amplitude of the 400-mHz oscillations of SBP. Acute administration of enalapril or hydralazine resulted in BP variability profiles, suggesting a reflexly mediated vascular sympathetic activation. In contrast, chronic angiotensin-converting enzyme (ACE) blockade with enalapril caused a significant decrease in the LF oscillations of BP. This could reflect a reduced sympathetic outflow to vascular smooth muscles.

Angiotensin II↗
PubMed1992

[Initial otorhinolaryngologic lesions of lepromatous leprosy].

The paper deals with a topic rarely treated in the bibliography: a carrier of cutaneous and otolaryngologic lesions suspicious of lepromatous leprosy. The AA. made a survey of the typical ENT manifestations of the generalized disease--lepromatous leprosy--and recall the more characteristic diagnostic tests as well as the guide lines of the treatment.

Adult↗
PubMed1991

Cardiovascular and adrenaline-releasing effects of the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin in streptozotocin diabetic rats.

The 5-hydroxytryptamine1A (5-HT1A) receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) has been reported to trigger sympathoinhibition, as evidenced by its cardiovascular effects, and adrenal catecholamine secretion. The purpose of this study was to analyze the cardiovascular and adrenaline-releasing effects of 8-OH-DPAT in 1 week streptozotocin diabetic rats. 8-OH-DPAT-induced changes in mean arterial pressure (MAP) and heart rate (HR) were determined directly in anesthetized rats, whilst changes in plasma adrenaline (and plasma corticosterone and glucose) levels were analyzed in conscious rats. Resting blood pressure and heart rate were diminished in diabetics, when compared with controls. These changes were associated with a decrease in body weight and a marked increase in resting plasma glucose levels. Diabetes did not affect MAP response to 8-OH-DPAT, except for a decrease in the amplitude of MAP maximal fall, which was associated with a diminished bradycardic response to 8-OH-DPAT. Blood pressure response to prazosin (0.5 mg/kg) in 8-OH-DPAT-pretreated rats was also diminished in diabetics. Lastly, diabetes prevented the adrenaline-releasing and hyperglycemic effects of 8-OH-DPAT (250 ug/kg).

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1991

Effects of clonidine on blood pressure and heart rate responses to an emotional stress in the rat: a spectral study.

1. The fluctuations that underlie the spontaneous variability of blood pressure (BP) and heart rate (HR) were investigated in conscious normotensive rats using power spectral analysis. 2. Air jet stimulation determined a significant BP rise associated with a tachycardia. This environmental mild stressor amplified the 195-605 mHz oscillations of HR which are under autonomic control. No habituation to this stressor was observed since a second stimulation determined similar responses. 3. Clonidine (10 micrograms/kg, i.v.) prevented the BP rise normally associated with air jet stimulation. In addition, clonidine dramatically reduced the amplitude of BP and HR oscillations in the frequency region of 195-605 mHz. 4. It is concluded that a mild emotional stressor elicits in normotensive rats a rise in BP and HR associated with modified spectral profiles reflecting sympathetic hyperactivity. Clonidine minored the effects of stress on BP and HR variability and also prevented BP elevation.

Animals↗
PubMed1990

Platelet phospholipase C activity in salt-dependent hypertension.

In spontaneously hypertensive rats (SHR), enhanced responsiveness of phospholipase C has been reported in various cells and tissues. In SHR and in some patients with essential hypertension particularly, the increased phospholipase C responsiveness of platelets has been described as involved in the hyperreactivity to thrombin. To determine the relation between such an enzymic abnormality and hypertension, the platelet phospholipase C activity was investigated in various models of experimental hypertension (i.e., in the Dahl salt-resistant and salt-sensitive strains inbred by John Rapp at Toledo, Ohio, SR/Jr and SS/Jr, respectively) fed either on a low or a high NaCl-containing diet, and in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. In phosphorus-32-prelabeled platelets, phospholipase C was determined by measurement of the thrombin-induced [32P]phosphatidic acid formation; the labeling of the P47 protein with 32P was also measured. In parallel experiments, the platelet reactivity was assessed by measurement of the thrombin-induced serotonin release. Under thrombin (0.05-0.5 units/ml) stimulation, phospholipase C activity, [32P]P47 labeling, and serotonin release were significantly increased in SS/Jr rats fed a high NaCl diet compared with SS/Jr rats fed a low NaCl diet. NaCl-rich diet did not modify phospholipase C in SR/Jr rats. Platelet reactivity and phospholipase C responsiveness were also normal in DOCA-salt hypertensive rats compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Platelet phosphatidylcholine turnover in experimental hypertension.

To gain insight into the membrane alteration that could account for the hyperresponsiveness of platelets in hypertension, we have investigated whether, in resting platelets of hypertensive rats, the metabolism of phospholipids was modified. Because preliminary results indicated a specific acceleration of phosphatidylcholine turnover in spontaneously hypertensive rats, the possible relation between such an abnormality and hypertension was investigated by studying phosphorus-32 labeling of phosphatidylcholine (taken as an index of its turnover) in various experimental models of hypertension. The data showed that phosphatidylcholine turnover 1) was considerably increased in platelets from spontaneously hypertensive (even at the prehypertensive stage) and stroke-prone rats compared with Wistar or Wistar-Kyoto control rats, 2) did not differ between deoxycorticosterone-salt-treated hypertensive and control rats, and 3) was increased in Dahl salt-sensitive rats fed a high NaCl diet (hence hypertensive rats), compared with either the rats fed a low NaCl diet or the salt-resistant rats. These results indicate that an increase in phosphatidylcholine turnover is a consequence of neither hypertension nor high salt intake and appears likely to be of genetic origin. These data allow us to suggest the existence, in platelets, of a relation between phosphatidylcholine turnover, free cytoplasmic Ca2+, and responsiveness to stimuli. Because phosphatidylcholine is assumed to participate in signal transduction, an increase in its turnover in platelets might be considered as a primary membrane abnormality that, in primary hypertension, results in platelet hyperresponsiveness.

Animals↗
PubMed1990

[Ethmoid-maxillary mucocele as a manifestation of primary lymphoma of the orbit].

A primary lymphoma of the orbit developed at par with a mucocele of the sinus (perhaps originated by the tumor) made very difficult the diagnosis of the patient. About this case the AA, consider the aspects more interesting of the primary lymphoma of the orbit and the possible influence of this kind of tumors as starting point of the mucocele.

Adult↗
PubMed1989

[Phospholipase C hypersensitivity in hypertensive rats results from innate and acquired factors].

In spontaneously hypertensive rats (SHR), enhanced activity of phospholipase C (PLase C) has been reported in various cells and tissues. In particular, the increased PLase C activity of platelets has been described as being involved in the hyperactivity to thrombin exhibited by these cells in SHR and in some patients with essential hypertension. In order to determine the relationship between such an enzymic abnormality and hypertension, the PLase C activity of platelets was investigated in various models of experimental hypertension, i.e. Dahl rats and DOCA-salt hypertensive rats. PLase C activity was determined by measuring the thrombin-induced 32P-phosphatidic acid (32P-PA) formation from 32P-prelabeled platelets. In parallel, experiments on the platelet reactivity was assessed by measuring the thrombin-induced serotonin secretion from 3H-serotonin prelabeled platelets. In Dahl salt-resistant rats (DR), the blood pressures were 123 +/- 6 and 118 +/- 7 mmHg for animals fed a low (0.3 p. 100) and high (4 p. 100) salt diet, respectively; the blood pressures of Dahl salt-sensitive rats (DS) were 159 +/- 6 and 202 +/- 11 mmHg, respectively. Hypertensive rats of the DOCA/salt--treated group exhibited a blood pressure of 210 +/- 8 mmHg compared with 137 +/- 4 mmHg for those of the control group. At rest (ie before stimulation) the platelets of all groups of animals behave similarly with respect to the incorporation of 32P and its metabolism into phospholipids as well as the uptake of serotonin. These data indicate therefore that platelets were in a similar quiescent status.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

[Anatomical basis for the surgical use of the cephalic vein (V. Cephalica). 74 anatomical dissections. 189 surgical dissections].

The delto-pectoral portion of V. Cephalica was dissected 189 times during surgery and 74 times on cadavers. In 8 out of 10 cases the disposition was of the classical type and the diameter was wide enough to allow catheterization with a 3,4 mm catheter. In 2 out of 10 cases the vein was absent or toothin. This anomaly was most often unilateral with a normal disposition on the other side in 2/3 of cases.

Arm↗