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Biomedical subjects

C Julien

Publications and source records attributed to C Julien.

At least 19 recordsLinked to original sources
PubMed1992

Arterial baroreflex control of heart period is not related to blood pressure variability in conscious hypertensive and normotensive rats.

1. The short-term (within 30 min periods) and the long-term (among 30 min periods) variabilities, expressed as variation coefficients, of blood pressure (BP) and heart period (HP) were studied using a computer analysis of BP recordings in freely moving genetically hypertensive (LH), normotensive (LN) and low BP (LL) rats of Lyon strains at ages 5, 9, 21 and 40 weeks. The baroreflex control of HP was estimated with the slope of the linear relationship between systolic BP (SBP) and HP (SBP-HP slope) computed after phenylephrine and nitroglycerin injections. 2. Short-term variability of BP increased between 5 and 9 weeks of age and then remained stable. Hypertension was accompanied by an increase in both short- and long-term variabilities of diastolic BP in adult rats. 3. A sharp increase in SBP-HP slope was observed between 5 and 9 weeks of age in LN rats. SBP-HP slope of LH rats increased slightly up to 21 weeks but remained lower than that of normotensive controls. 4. The weak inverse correlation existing between SBP-HP slope and BP variability appeared to be mediated by the BP level. In addition, atropine which is known to abolish almost completely the SBP-HP slope, did not increase BP variability. It is concluded that SBP-HP slope is not linearly associated with BP variability in conscious rats.

Aging↗
PubMed1992

Cardiovascular habituation to emotional stress in Lyon hypertensive rats.

1. Intra-aortic blood pressure was recorded continuously in freely moving genetically hypertensive (LH), normotensive (LN) and low blood pressure (LL) rats of the Lyon strain during two 11 h periods (08:00-19:00 h). During the first period (control), the animals were left undisturbed and during the second period (stress), a jet of air was applied for 20 min every hour. Urine was collected simultaneously and analysed for its content in norepinephrine and epinephrine. 2. The first exposure to the stressor induced larger increases in blood pressure and heart rate in LH than in LN and LL rats. However blood pressure and heart rate responses to the 10 following stressors decreased in LH rats while they remained stable in LN and LL animals. 3. Repeated stress exposure induced significant increases in epinephrine excretion in both LN and LL but not in LH rats. 4. It is concluded that LH rats exhibit marked cardiovascular habituation to repeated stress. Taken together with the lack of stress-induced sympathoadrenal activation, this suggests a reduced level of emotional responsiveness in Lyon hypertensive rats.

Adrenal Medulla↗
PubMed1992

[Role of sympathetic nerve fibers in hemodynamic responses to stress in rats].

Hemodynamic responses to acute stress exposure were studied in normotensive control (C) and chronically sympathectomized (S) rats. Male Sprague-Dawley rats received daily sc injections of either saline (C) or guanethidine (S) from 1 to 13 weeks of age. Doppler flow probes were then implanted for the measurement of blood velocity in the sub-diaphragmatic aorta, superior mesenteric artery and distal aorta (hindquarters). After 10 days of recovery and 24 hours before the study, the caudal artery was cannulated. In the conscious freely moving rats, mean arterial pressure (MAP), heart rate (HR) and indices of regional blood flows and vascular conductances (G as blood flow/MAP ratio) were recorded beat to beat, before and during emotional stress (jet of air for 2 min). In basal conditions, mean values of MAP and HR were similar in C (107 +/- 2 mmHg; 399 +/- 8 bpm, n = 9) and S (106 +/- 3 mmHg; 384 +/- 12 bpm, n = 7) rats. The effects of stress on MAP, HR, aortic (AoG), mesenteric (MeG) and hindquarters (HqG) vascular conductances are expressed as percentage changes from baseline (delta): [table: see text] These results highlight the role of vascular sympathetic nerves in pressor responses and systemic and mesenteric vasoconstrictions induced by stress in the rat. They also indicate that vasodilatation in the hindquarters vascular bed is not secondary to withdrawal of sympathetic vasoconstrictor tone but rather to active phenomena which do not involve the stimulation of vascular beta 2-adrenoceptors by neuronal catecholamines nor the release of vasodilator cotransmitters from the sympathetic nerve endings.

Adrenergic Fibers↗
PubMed1991

Trophoblast-like cells sorted from peripheral maternal blood using flow cytometry: a multiparametric study involving transmission electron microscopy and fetal DNA amplification.

Three monoclonal antibodies (MAbs) against trophoblast (GB17, GB21, and GB25) and flow cytometry were used to sort trophoblast-like cells (TLCs) from peripheral blood of pregnant women. Sorted TLCs were processed for electron microscopy and fetal DNA amplification of the Y-specific sequences from mothers carrying male fetuses. At the ultra-structural level, most of the nucleated cells had the morphology of leucocytes, suggesting maternal contaminants, and we did not find the characteristic features of the free intervillous trophoblast cells. Nevertheless, polymerase chain reaction (PCR) analysis showed an amplification of Y-specific sequences in two out of three samples of sorted TLCs. These results suggest that besides the maternal leucocytes, sufficient trophoblast nucleated fetal cells can be obtained using cell enrichment by sorting. This sensitive method holds promise for non-invasive prenatal diagnosis of fetal sex and if sufficient Y(positive) nuclei are found, for the diagnosis of selected numerical chromosome abnormalities.

Antibodies, Monoclonal↗
PubMed1991

Nonorgan-specific autoantibodies in individuals infected with type 1 human immunodeficiency virus.

Fifty-six human immunodeficiency virus-1-positive asymptomatic carriers were tested for the presence of a variety of nonorgan-specific autoantibodies. Antinuclear antibodies were detected in 34 sera, of which 27 were directed to the mitotic spindle apparatus and all were of the IgG isotype. Anti-Golgi complex, anti-centriole, and anti-vimentin antibodies were also present in 20.4, and 4 sera, respectively. Ten patients had less than 500 CD4-carrying T lymphocytes per cubic millimeter. Nine of them had more than one autoantibody. No correlation could be demonstrated between the number of autoantibodies and the level of serum immunoglobulins.

Adult↗
PubMed1991

Autonomic nervous system and cardiovascular variability in rats: a spectral analysis approach.

Mechanisms underlying systolic (SBP) and diastolic (DBP) blood pressure and heart rate (HR) beat-to-beat variability were investigated using spectral analysis in conscious genetically normotensive (LN) and hypertensive (LH) adult rats from the Lyon strains. In LN rats, basal SBP, DBP, and HR spectra exhibited peaks in low (LF: 0.38-0.45 Hz) and high (HF: 1.04-1.13 Hz) frequencies. The LF peak of SBP, and even more of DBP, could be attributed to the influence of the sympathetic nervous system as it disappeared after destruction of the sympathetic nerves or a combined alpha- and beta-adrenoceptor blockade, whereas it was higher after blockade of the parasympathetic system. The HF peak of HR, linked to the respiratory rate, was abolished by the parasympathetic system blockade, whereas those of SBP and DBP were enhanced. In LH rats, which exhibit a lower sympathetic activity, the LF peaks of SBP and DBP were less distinct compared with LN controls. We conclude that the LF peak of DBP and the HF peak of HR are likely to represent useful estimates of the sympathetic vascular control and of the parasympathetic cardiac control, respectively.

Angiotensin Receptor Antagonists↗
PubMed1991

Renal denervation does not prevent hypertension in Lyon hypertensive rats.

The effects on blood pressure (BP) of a single and repeated renal denervations (RD) were compared in genetically hypertensive (LH) and normotensive (LN) rats of the Lyon strain. Indirect BP was measured by the tail-cuff method, and direct BP was measured through an aortic catheter in conscious quiet rats receiving a normal-sodium diet. Single RD (10 wk of age) did not reduce BP in both LN and LH rats. Repeated RD (4, 7, and 10 wk of age) partly prevented the age-related increase in tail-cuff BP but did not affect the directly recorded BP in 11-wk-old LH rats. Single and repeated RD reduced the renal norepinephrine content by greater than 90%. Both procedures did not alter the BP lowering effects of angiotensin-converting enzyme inhibition and of ganglionic blockade. It is concluded that renal nerves are not necessary for the development and the maintenance of hypertension in LH rats.

Animals↗
PubMed1991

Blood pressure maintenance in hypertensive sympathectomized rats. I. Adrenal medullary catecholamines.

To assess the role of the sympathetic nervous system in the development of genetic hypertension, blood pressure (BP) was recorded in conscious adult Lyon hypertensive (LH) and normotensive (LN) rats that had received daily injections of saline or guanethidine at 1-13 wk of age. Guanethidine abolished the pressor response to tyramine, decreased plasma norepinephrine by greater than 70% and plasma 3,4-dihydroxyphenylglycol by approximately 90%, and did not change plasma epinephrine. Bilateral adrenalectomy further reduced plasma norepinephrine to 8 and 5% of control levels in LH and LN rats, respectively. BP was lowered (-7%) in sympathectomized rats, but the mean absolute BP difference between LH and LN rats was unaltered. Despite marked supersensitivity to alpha-adrenoreceptor stimulation, phentolamine induced only a small transient depressor response, which was abolished by adrenalectomy in sympathectomized rats. It is concluded that the sympathetic nervous system is not necessary for the development of hypertension in LH rats. After sympathectomy, circulating catecholamines, which mostly derive from the adrenal medulla, play only a minor role in BP maintenance.

Adrenal Medulla↗
PubMed1991

Blood pressure maintenance in hypertensive sympathectomized rats. II. Renin-angiotensin system and vasopressin.

This study examined the contribution of the main pressor systems to the residual hypertension exhibited by genetically hypertensive (LH) rats of the Lyon strain after early chronic sympathectomy with guanethidine. Blood pressure (BP) was recorded in conscious LH and normotensive control (LN) rats, either intact or sympathectomized, during sequential blockade of the renin-angiotensin system, vasopressin receptors, the autonomic nervous system, and finally after maximal vasodilation with hydralazine. In sympathectomized rats 1) renin-angiotensin system blockade equally reduced BP in both strains, whether it was realized before (-20%) or after (-30%) vasopressin antagonism; 2) isolated vasopressin antagonism decreased BP in LH (-8%) but not in LN rats; 3) autonomic blockade and hydralazine induced additional decreases in BP that were similar in both strains; and 4) intermediate and final levels of BP remained always higher in LH than in LN rats. It is concluded that, after sympathectomy, BP is maintained primarily by the renin-angiotensin system. In sympathectomized LH rats, the maintenance of hypertension does not depend on hyperactivity of the main pressor systems but rather on an increase in the intrinsic vascular resistance that develops in the absence of the sympathetic innervation of the vessels.

Angiotensin I↗
PubMed1991

[Professor and mentor in surgery].

The surgical monitor supervises students, teaches them various skills and evaluates their progress. In the course of overseeing the students' clinical practice, the monitor helps them apply the theoretical concepts learned in class to the reality of life on the ward. If the experience is not properly planned, the goals of the clinical practicum, post-operative care, the student's personal goals and those of the monitor can become confused and intertwined. The author discusses the socialization process every student must go through to forge her own professional identity. Students must also adapt to the hospital "sub-culture", which can be dramatically different from nursing school, and they must learn to think critically and analytically. The author, himself a monitor, explains how the students' progress is evaluated. The monitor presents himself as a confident, independent role model, equal to others on the health care team. The article concludes by pointing out that the Quebec Ministry of Education wants students to become integrated into the future job market; the new nursing focus is educating people who can be independent generalists. To sum up: the monitor is a coach, critic, consultant, supervisor, and advisor--all rolled into one.

Humans↗
PubMed1991

[Origin and role of circulating catecholamines in the normotensive sympathectomized rat].

Early chronic treatment with guanethidine destroys peripheral sympathetic nerves while sparing the adrenal medulla, and does not lower blood pressure (BP) in conscious normotensive rats (Julien et al. Am J Physiol 1990; 259: H1337). Therefore, the origin and role of circulating catecholamines (CAs) in BP maintenance were examined in conscious normotensive control, sympathectomized (SNX)--daily s.c. injections of guanethidine from 1 to 13 weeks of age--and sympathectomized-adrenalectomized (SNX-A) rats by measuring i) their plasma CAs (norepinephrine, NE and epinephrine, E) and 3,4-dihydroxyphenylglycol (DHPG) by HPLC-FD, and ii) their mean BP (MBP) responses to phenylephrine and phentolamine (5 mg/kg i.v.). The doses of phenylephrine that produced similar MBP rises were 3 micrograms/kg in controls (44 +/- 4 mmHg) and 1.5 micrograms/kg in SNX (47 +/- 3 mmHg) and SNX-A (48 +/- 2 mmHg) rats. Results are as follows: [table: see text] In conclusion, in conscious normotensive SNX rats: (1) most of the circulating NE is of adrenomedullary origin and plasma DHPG derives from neuronal NE; (2) due to supersensitivity of the cardiovascular system, stimulation of alpha-adrenoreceptors by circulating CAs play a significant role in BP maintenance.

Adrenal Medulla↗
PubMed1991

[Role of sympathetic nervous system on blood pressure and heart rate variabilities in the rat: spectral analysis].

The role of the sympathetic nervous system (SNS) in the genesis of the beat-to-beat variability of blood pressure (BP) and heart rate (HR) was studied using spectral analysis. The SNS activity of genetically normotensive rats of the Lyon strain (LN) was abolished in 2 ways: 1) adrenergic blockade with administrations of phentolamine (PHE, 5 mg/kg i.v.) or propranolol (PRO, 5 mg/kg i.v.) or both drugs (PHEPRO) or 2) destruction of the sympathetic fibers with an early chronic treatment with guanethidine (LNSx). HR and systolic (SBP) and diastolic (DBP) BP spectra were computed using 50 to 100 stationary sequences from 1 h beat-to-beat recordings and covered the 0.015-3.85 Hz frequency band. In LN rats, spectra obtained in baseline conditions exhibited a high-frequency peak (HF, 1.04-1.13 Hz) related to the respiratory frequency and a mid-frequency peak (MF, 0.38-0.45 Hz). Concerning BP, the alterations of the SNS induced significant decreases of the total modulus (mmHg/Hz1/2) of the MF band (0.27-0.74 Hz): [formula: see text] In addition, the MF peak of SBP and DBP spectra was abolished in LNSx and PHEPRO rats. Concerning HR spectra, the moduli of all the frequency components were decreased in PHEPRO rats only. In conclusion, the similarity of the results observed in LNSx and PHEPRO rats shows that the MF oscillations of BP depend in a large extent (65%) on the action of the sympathetic fibers and involve the activation of both alpha- and beta-adrenoceptors. Concerning DBP, this effect is especially mediated by the activation of alpha-adrenoceptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effects of sympathectomy on blood pressure and its variability in conscious rats.

To further assess the role of the sympathetic nervous system (SNS) in the control of blood pressure (BP), continuous recordings of BP were performed in conscious freely moving rats that had received daily injections of guanethidine or saline from 7 to 90 days of age. Guanethidine extensively destroyed the peripheral sympathetic fibers as indicated by marked decreases in the norepinephrine content of the heart and kidneys and the absence of pressor response to tyramine injection. Such a chronic sympathectomy did not alter the BP and heart rate (HR) levels but markedly enhanced the BP variability while the HR variability and the sensitivity of the cardiac baroreceptor reflex were not altered. Angiotensin-converting enzyme inhibition with perindopril induced a rapid fall in BP and normalized the BP variability in sympathectomized animals. It is concluded that in rats, the SNS is not necessary for the full development of the BP level but is essential to buffer the spontaneous variability of BP. After sympathectomy, BP is maintained at nearly normal levels mainly through activation of the renin angiotensin system.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1990

Antirenin immunization versus angiotensin converting enzyme inhibition in rats.

The effects of specific active immunization against renin were compared with those of chronic angiotensin converting enzyme (ACE) inhibition. Male spontaneously hypertensive rats (SHR) were immunized (SHR-I) (n = 10) against pure murine renin (four injections of 30 micrograms/kg s.c.) or received (SHR-P) (n = 11) a converting enzyme inhibitor (perindopril, 2 mg/kg/day per os for 4 weeks). Sham-immunized SHR (SHR-S) (n = 12) and normotensive Wistar-Kyoto (WKY-S) (n = 12) rats served as controls. At 15 weeks of age, 24-hour average blood pressure was obtained in freely moving rats using intra-aortic pressure recording with computer analysis. Antirenin immunization induced high circulating titers of antibodies, a fall in plasma renin activity (-95%), and urinary excretion of mineralocorticoids. Perindopril abolished the pressor response to angiotensin I, whereas plasma ACE was only partly (-56%) decreased. It also increased plasma renin activity and did not alter the urinary excretion of steroids. Both immunization and perindopril allowed the blood pressure of SHR to return to the level of WKY-S rats and reduced the left ventricular weight. These decreases were associated with an elevated sympathetic nervous system activity as indicated by increases in the urinary excretion of catecholamines and their metabolites. It is conclude that, apart from an unaltered steroid synthesis, most of the cardiovascular effects of chronic ACE inhibition are similar to those of antirenin immunization, thus indicating that blockade of the circulating and renal renin-angiotensin system accounts for most of the effects of ACE inhibitors.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1990

[Role of renin-angiotensin system and vasopressin in the control of blood pressure in genetically hypertensive rats after sympathectomy].

Early chronic sympathectomy does not normalize blood pressure (BP) in genetically hypertensive rats of the Lyon strain (LH). The purpose of this study was to examine the role of the renin angiotensin system (RAS) and vasopressin in the residual hypertension exhibited by LH sympathectomized rats. Chronic sympathectomy was achieved by treating male LH and control normotensive LN rats with guanethidine sulfate between 1 and 13 weeks of age (60 mg/kg daily from day 7 after birth to day 25, 30 mg/kg daily from day 26 to day 70 and 30 mg/kg every other day from day 71 to day 90). At 14 weeks of age, catheters were inserted into the lower abdominal aorta and inferior vena cava via the left femoral artery and vein. After 2 days of recovery, BP was continuously recorded in the conscious freely moving animals during 3 consecutive 1-hour periods: before and after administration of either an angiotensin converting enzyme inhibitor (perindopril 2 mg/kg i.v.) or a selective vascular vasopressin antagonist [beta-mercapto- beta,beta-cyclopentamethylenepropionyl1, O-Me-Tyr2, Arg8-vasopressin, AVPX 10 micrograms/kg i.v.) and finally after conjoint administration of both drugs. At the end of each period, the efficacy of blockade was verified by the disappearance of pressor responses to respective agonists (angiotensin I 150 ng/kg i.v., Arg8-vasopressin 10 ng/kg i.v.). Chronic treatment with guanethidine resulted in the disappearance of pressor responses to tyramine (250 micrograms/kg i.v.) indicating complete functional denervation of the vessels. Under basal conditions, the 1-hour average value of mean BP (MBP) was higher in LH than in LN sympathectomized rats (134 +/- 3 vs 104 +/- 2 mmHg, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Injections].

This article deals with the injection techniques used for administering medication in the vastus lateralis and the ventral gluteal muscles. Both sites are easy to locate and safe for injection. The vastus lateralis site, in particular, is commonly used for babies, children and adults.

Adult↗