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Biomedical subjects

S Boghossian

Publications and source records attributed to S Boghossian.

At least 19 recordsLinked to original sources
PubMed2005

Effect of treatment with dexamethasone on protein intake in adult and old Lou/c/jall rats.

A deleterious decrease of protein intake had been evidenced in Lou/c/jall rats during ageing. This result could be induced by an impaired regulation of feeding behaviour. Glucocorticoids inducing specific amino-acid needs for gluconeogenesis and for the synthesis of inflammatory proteins by the liver, we investigated the age-related effect of a 4-days treatment with dexamethasone (DEX) on caloric and protein intake. Males and females aged 7, 19, 25 and 31 months received 573.6 +/- 65.6 microg/(kg day) of dexamethasone via the drinking water. Body weight (BW), caloric and macronutrients intakes were monitored during treatment and during 10 days after the treatment. A strong hypophagia was seen during treatment in all groups, which was mainly due to a decrease in fat intake. In the same time, rats maintained their protein intake so that protein became the main macronutrient of the diet in most of the groups. However, older males showed a lesser efficiency in adjusting their diet. These results are in agreement with previous data obtained in a protein deprivation study. They lead to the conclusion that the loss of appetite for protein in old age probably does not reflect a loss of ability to choose the needed amount of protein. We can hypothesise that the decrease of protein intake in old rats could be due to some inadequacy of casein to the metabolic requirement of aged animals.

Aging↗
PubMed2002

Old as mature LOU/c/jall rats enhance protein selection in response to a protein deprivation.

Previous experiments have shown a strong decrease in protein consumption as rats grow old. This result could be induced by an impaired regulation of feeding behaviour. Present study investigated the ability of ageing rats to adapt their protein intake to protein requirements. Four groups of self-selecting LOU/c/jall male and female rats (4, 16, 22, 28 months at the beginning of the experiments) were submitted to 4-days of protein deprivation periods while their macronutrient intakes were monitored. Moreover, they were submitted to a 4-day fasting period. After reintroduction of proteins, old and senescent rats were able to increase their protein intake in response to the specific protein need created by the protein deprivation. They were also able to increase caloric intake after the fasting period. These results led to the conclusion that the loss of appetite for protein observed with ageing reflects rather an adaptation than an impairment of the regulation of macronutrient choice. Another important observation was that older animals did not recover initial body weight after a body weight loss even if they ate as many calories as younger animals. This data supports a decrease in the efficacious utilization of body fuels in old and senescent rats.

Adaptation, Physiological↗
PubMed2001

Effect of morphine on caloric intake and macronutrient selection in male and female Lou/c/jall rats during ageing.

Previous studies have showed a shift of preferences from carbohydrate to fat in the Lou/c/jall rat with advancing age when they are submitted to a self-selection procedure. Protein intake also decreased according to the age, earlier for males (after 16 months) than for females (29 months). The present study aimed at investigating the mechanism underlying these modifications. We analysed the effect of the reference mu agonist, morphine (5 mg/kg subcutaneous), on the caloric intake, body weight and macronutrient intake of 30 male and 30 female rats divided in four age groups: young adults (10), mature (17), old (24) and senescent rats (29 months). During the experiment, animals had the choice between separate sources of the three pure macronutrients. Morphine injection reduced total daily caloric intake and induced a decrease in body weight. The weight loss was age- and sex-related (males and old rats were more affected by the drugs). The injection of morphine evoked a triphasic influence on the chronology of the intake. A brief (1 h) hypophagia was followed by an hyperphagia (3 h) and a persistent hypophagia (8 h). No modification in the diet composition was observed. These results did not support a clear involvement of the opioid system concerning the modifications in macronutrient rates in diet previously observed across ageing.

Aging↗
PubMed2001

Effects of peripheral and central administration of GHRH on feeding in aging LOU rats.

In aging LOU rats, a decreased protein intake is restored by GH administration. To study the contribution of GHRH to macronutrient selection, hGHRH NH(2) was administered sc. (1 mg/kg B.W./day/14 days) or icv. (4 and 40 pmol/rat) to 11-, 19-, 24- and 28-month-old rats. Sc. administration induced a decreased food and lipid intakes from 24 months of age and a transient stimulation of protein intake in 19-month-old and older low protein eaters (<10% protein/total intake). Icv. administration induced decreased food and lipid intakes in all age groups. These results suggest that GHRH may regulate feeding through pituitary and/or hypothalamic GHRH receptor mechanisms.

Animals↗
PubMed2000

A moderate swimming exercise regularly performed throughout the life induces age and sex-related modifications in adaptive macronutrients choice.

The ability of laboratory rats to adapt food intake to needs is well-known. The present study investigates changes in this adaptive behavior when animals grow old. A cohort of male and female Lou/c/jall rats was regularly submitted to an exercise throughout their life (6 consecutive days of moderate intensity training (3x15 min/day)). Caloric intake and macronutrients selection during exercise and post-exercise periods were compared to the pre-training period. During swimming, a decrease in both caloric intake and fat selection was observed and an increase in protein intake was specifically seen in female groups. However, males were unable to modify the diet composition (macronutrient rate) from 16 months of age, whereas females were able to do it until 24 months of age. The present results suggest a sex-dependent loss of capacity of adjusting feeding behavior to metabolic needs when animals grow old, may be due to a deterioration of the central control of food intake.

Adaptation, Physiological↗
PubMed2000

Age-related changes in adaptive macronutrient intake in swimming male and female Lou rats.

To evaluate the age-related changes in capacity to adjust the nutrient intake to needs, self-selecting male and female Lou/C/jall rats of 4, 6, 12, 16 and 23 months of age were submitted to a swimming exercise. They were given 6 consecutive days of moderate intensity training (3 x 15 minutes per day). Exercise and postexercise periods were compared with results from the pretraining period. During swimming, a body weight loss and a decrease in both caloric intake and fat selection were observed. This effect was more marked in older groups compared to 4 month-old groups. An increase in protein intake was observed in females, specially in older groups, whereas no effect was seen in males. The ability to increase caloric ingestion and regain weight during the postexercise period decreased with advancing age and was better in females than in males. We also showed an age-related effect on the recovery of initial nutrient intake rate that was more pronounced and more precocious for males. Moreover, males tended to decrease their protein intake, whereas females significantly increased it. The present findings suggest a decrease of capacity of adjusting feeding behavior to metabolic needs in aged rats, may be due to a deterioration of the central control of food intake.

Adaptation, Physiological↗
PubMed2000

Age-related changes in nociception and effect of morphine in the Lou rat.

Little is known about how the ageing process affects pain sensitivity and a relevant animal model is therefore required. The effect of age on pain reactivity in animals has been investigated by several experimenters but the results are conflicting. Four groups of male and female Lou/C/Jall rats (4-29 months old) were used for our study. Four pain tests based on evaluation of reflex or more integrated behaviours after a thermal (tail immersion test) or mechanical (paw pressure test and von Frey test) stimulation were used. With mechanical stimulus, a significant decrease in the pain threshold across age was observed, females were more sensitive than males. This increase in nociceptive sensitivity to mechanical stimulation was more pronounced on integrated behaviours (struggle reaction) than on withdrawal reflex. An age-related increase in sensitivity was found on von Frey test. No effect on the latency of reflex induced by thermal stimulation was observed. In addition, a decrease in the spontaneous motor activity during exploration was observed across ageing; this effect was more marked for the females. The effect of morphine at doses of 1, 3 and 9 mg/kg (s.c.) decreased in intensity across ageing. These data demonstrate the need to use (1) various noxious stimuli because differences were observed in the modification of pain reactivity according to the nature of the stimulus; (2) various pain parameters and particularly integrated behaviours; (3) several age groups. In addition, Lou/C/Jall rat could be a useful model for studying of effect of age on pain.

Aging↗
PubMed1998

Age-related changes in adaptive mechanisms of macronutrient self-selection: evidence for a sexual dimorphism.

The effect of aging on patterns of food intake and nutrient selection was investigated using a longitudinal study. Male (n = 10) and female (n = 10) Wistar-Lou rats from 4 to 28 months of age were repeatedly submitted to a macronutrient self-selection (S-S) regimen while controls were maintained under a standard chow diet (Std). An age-related shift of preferences from CHO to fat diets, and a decrease in protein intake for both males and females were evident. Nevertheless, all these modifications were more pronounced and precocious for males. Physical exercise (45 min/day of swimming, on 6 days) induced a body weight loss and an hypophagia more pronounced for males than for females. S-S regimen results revealed that hypophagia concerned exclusively fat intake and that females significantly increased protein intake during and after the exercise period. Study of longevity curves showed a decrease of the mortality in S-S submitted male rats compared to control rats. This study shows that aging induces a sex-difference in feeding patterns which undoubtedly reveals a sex-difference metabolic requirements. Moreover, these results suggest that allowing rats to select macronutrient intakes could delay the process of senescence.

Adaptation, Physiological↗
PubMed1998

[Sinus node modification by catheter using radiofrequency current in a patient with inappropriate sinus tachycardia. Evaluation of early and late results].

This article reports the early and late results of a patient in whom radiofrequency current was used to ablate an incessant inappropriate sinus tachycardia. During successful radiofrequency application there was a sudden change of rate and subsequent emergence of a stable rhythm with the same sinus node P wave characteristics. During follow-up, normal cardiac cycles were still present after six months of the procedure, although the patient still complained of palpitations, suggesting no correlation with the heart rate.

Adult↗
PubMed1996

Radiofrequency catheter ablation of an incessant supraventricular tachycardia initiated by a Hisian parasystole.

The coexistence of a parasystolic focus, tachycardia dependent right bundle branch aberrancy, and an AV accessory pathway is reported here. This condition was present in a 40-year-old man, which led to an incessant AV reciprocating tachycardia. Further electrophysiological study revealed that the parasystolic focus was located somewhere in the His bundle; endocardial mapping disclosed a right posterior accessory pathway. Radiofrequency current was delivered at the atrial level of the right posterolateral AV groove and successfully ablated the accessory pathway, leading to a dramatic improvement in cardiac function. In conclusion, the recognition of the electrophysiological mechanism of incessant supraventricular tachycardia was of crucial importance for the therapy decision. A definitive intervention using radiofrequency catheter ablation should be considered early and not postponed in patients with tachycardia-induced cardiomyopathy.

Adult↗
PubMed1995

[Ablation therapy of type I atrial flutter with radiofrequency].

PURPOSE--To present initial experience on radiofrequency (RF) ablation of atrial flutter (AFL) guided by anatomic and electrophysiologic parameters. METHODS--Eight patients (six males), mean-age of 42 +/- 17.5 years with chronic type I AFL (mean cycle length of 251 +/- 14.3 msec, range 240 to 280 msec) were undergone to RF catheter ablation applied between inferior vena cava (IVC) and tricuspid annulus (TA). Two had persistent and two the paroxysmal form. Two had surgical corrected congenital heart disease (atrial septal defect in 2 and ventricular septal defect in 1). Four had systolic dysfunction and 2, an atrial tachycardia associated with the AFL. RESULTS--Areas of slow conduction represented by fractionated potentials were recorded between IVC and TA in all patients. RF ablation was successful in 8/8 patients (100%). The mean number of RF applications was 9.2 +/- 6.2 (4-24). The successful ablation site was located in the isthmus between IVC and TA in seven patients and in the lateral wall in the patient with ASD. Successful sites had an early atrial activation preceding the atrial electrogram (range from -65 to -82 ms). In one patient the RF energy was successfully delivered between the atriotomy scar (AS) and IVC. After three months follow-up six remained free of recurrent AFL. One pt had type 1 AFL recurrence and one with ASD had a type II AFL. The Type II AFL was successfully ablated between AS and IVC. CONCLUSION--Fractionated potentials were commonly observed between IVC and T; AFL ablation can be guided by anatomic landmarks or electrophysiologic parameters; electrograms recorded at successful sites were early and never fractionated; the long-term evaluation must be analyzed prospectively.

Adult↗
PubMed1995

[Mechanisms and dynamics of episodes of progression of of 2:1 atrioventricular to high degree atrioventricular block].

PURPOSE: To evaluate the mechanisms and dynamics of episodes of progression to high degree (HD) atrioventricular (AV) block (B) analyzed during incremental atrial pacing (St), in patients with previous 2:1 His-Purkinje (HP) AVB. METHODS: Data from 4 patients were analyzed. All of them with history of syncope and ECG exhibiting 2:1 AVB with wide QRS pattern. The AVB was in the HP system (HPS) in all. Every patient was submitted to electrophysiologic study with incremental atrial pacing, by which the conduction sequences and the AV conduction ratios (AVR) were analyzed. The basal (B) cycle length (CL) was defined as the shortest interval between two conducted beats (spontaneous or pacing-induced). The incremental atrial stimulation was performed beginning with CL 10 msec shorter than BCL until reaching 250 msec. RESULTS: Nineteen episodes of progression to HD-AVB were seen. A) With StCL between 31 and 26% of BCL, AVR were 3:1, 4:1 and 5:1, with only one blocking zone (BZ) in the HPS; B) with StCL between 24 and 22% of BCL, AVR were 5:1, 7:2, 9:2e11:3. In this situation a 2nd BZ ensues-on proximal, site of a decremental conduction, situated in the AV node (AVN) or in the HPS, and the other (distal level) always in HPS; C) with StCL between 24 and 16% of BCL, AVR were 5:1, 6:1, 10:2, 11:2 and 12:3. Here, these AVR were explained by postulating 3 BZ where 2 were in AVN and 1 in HPS, or inversely with 1 in AVN and 2 in HPS. The decremental conduction occurred in 1 or 2 out 3 BZ and an integral conduction (like 2:1 or 3:1) in the others. CONCLUSION: The BCL is the determinant of the AVR observed. As the StCL is shortened (< 26% BCL) a 2nd or 3rd BZ in the AVN or in the HPS ensues. These observations suggest that the mechanisms and dynamics of progression to HD-AVB apply only during incremental atrial pacing and there is a clear difference with what has been observed with the progression occurring exclusively at AV node.

Aged↗
PubMed1994

[Identification of intracavitary electrograms predictive of success in ablation of anomalous pathways by radiofrequency].

PURPOSE: To analyze the characteristics of atrial (A) and ventricular (V) electrograms, AV and VA intervals relation to determine a precise radiofrequency ablation site. METHODS: A and V electrograms (EG) recorded at successful (group 1) and unsuccessful (group 2) sites in 22 patients submitted to RF catheter ablation were identified. Specific criteria as morphology, AV and VA intervals relation and the presence of an accessory pathway were analyzed. RESULTS: The shortest AV interval with a VEG that precedes the delta wave in the onset of the QRS recorded at the EKG leads was the best outcome predictor. The AV connection potential was only recorded in five out of 22 patients and did not interfere with the result when not present. The interval measured between the onset of the V electrogram and the onset (delta wave) of the QRS complex (V-d) varied from -4.9 to -11msec (m = 7.5 + 1.6) in G1 and from -6 to 15msec (m = 9.6 +/- 3) in G2 (p = 0.03). Unsuccessful sites had the VEG preceding the delta wave but the AV interval was not short. Success in the retrograde mapping of target site seems to be the presence of an atrial potential that occurs simultaneously with the nadir (S wave) of the QRS complex. CONCLUSION: Specific criteria such as morphology of the local VEG, a short AV or VA intervals and a VEG that precede the onset (delta wave) of the QRS identified a successful site for RF ablation. When present the accessory pathway potential indicates a high chance of a successful ablation; however when not present did not decrease the chance of success.

Adolescent↗
PubMed1993

[Radiofrequency ablation of incessant supraventricular tachycardia due to anomalous pathway of retrograde decremental conduction].

Woman, 46 years-old with incessant supraventricular tachycardia and tachycardiomyopathy. The diagnosis of a concealed retrograde long conduction time accessory pathway was obtained with the delay of the next atrial activation by delivering a ventricular premature beat during His bundle refratoriness. During electrophysiologic investigation the earliest atrial activation was found to be within the coronary sinus ostium. Two 25 watts applications of radiofrequency were followed by the interruption of the incessant supraventricular tachycardia. The patient has remained symptom free without recurrence for 60 days. Radiofrequency was effective for the treatment of this tachycardia.

Catheter Ablation↗
PubMed1993

[High-resolution electrocardiography in arrhythmogenic right ventricular disease].

PURPOSE: To determine the value of the high-resolution ECG for the differential diagnosis of arrhythmogenic right ventricular disease. METHODS: A group of 33 patients were studied, 16 males, mean age 34 +/- 16 years. All patients presented non-sustained or sustained or repetitive monomorphic ventricular tachycardias, with left bundle branch block morphology. The anatomic and functional evaluation of the right ventricle was made by a previous echocardiogram. No patient presented left ventricular or septal pathology. High-resolution ECG were obtained from a Corazonix-Predictor II program. In the filtered QRS was analyzed root mean square of the last 40ms QRS, the final lasting of the low amplitude signals < 40 microV and filtered QRS duration. Ten patients underwent to electrophysiological study with right ventricular mapping. RESULTS: The ventricular tachycardias was non-sustained in 18 patients, sustained in 8 and repetitive monomorphic in 7 patients. The echocardiogram was normal in 23 patients, and all these also presented normal high resolution ECG. Among the 10 patients with altered echocardiogram, 9 presented abnormal high-resolution ECG (sensibility 90%; specificity 100%; positive predictive value 100%; negative predictive value 96%; efficacy of the method to define the presence of manifested right ventricular pathology was 96%). Among the 10 patients with altered echocardiogram, 8 underwent to electrophysiological study. In all was detected an abnormal ventricular mapping and abnormal high-resolution ECG. CONCLUSION: The high-resolution ECG is an useful method to define a right ventricular manifested pathology in presence of arrhythmogenic disease of this cavity.

Adolescent↗
PubMed1990

Pretreatment with pentoxifylline improves the hemodynamic and histologic changes and decreases neutrophil adhesiveness in a pig fecal peritonitis model.

We investigated pentoxifylline (PTF) as a pretreatment of septic syndrome in pigs with fecal peritonitis. In the untreated group there was a progressive decrease in mean arterial pressure (MAP), cardiac output, mean pulmonary artery wedge pressure (WP), and a progressive rise in mean pulmonary artery pressure (MPAP), pulmonary vascular resistance (PVR), systemic vascular resistance (SVR), heart rate (HR), and core temperature (T). In those pigs given PTF there was a significantly smaller increase in SVR throughout and in PVR after 270 min. No significant differences were seen in MAP, MPAP, WP, HR, and T. Neutrophil adhesiveness did not change in the untreated group. However, it decreased markedly with PTF, both before and after peritonitis induction. Electron microscopy of the lungs, liver, and spleen in the test group showed severe damage, with endothelial disruption, capillary or sinusoidal occlusion, leukostasis, and neutrophil degranulation. Pretreatment with PTF attenuated these changes.

Animals↗