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Biomedical subjects

Y Pardo

Publications and source records attributed to Y Pardo.

At least 19 recordsLinked to original sources
PubMed2000

Exercise conditioning and heart rate variability: evidence of a threshold effect.

BACKGROUND: A protective effect of exercise in preventing sudden cardiac death is supported by studies in healthy populations as well as in patients with cardiac disease. The mechanisms involved in this protective effect are unknown. HYPOTHESIS: We hypothesized that exercise conditioning would beneficially alter autonomic nervous system tone, measured by heart rate variability. METHODS: We prospectively studied 20 cardiac patients enrolled in a Phase 2 12-week cardiac rehabilitation program following a recent cardiac event. The patients underwent 24 h Holter monitoring at program entry and 12 weeks later. Heart rate variability analysis was assessed for both time domain and spectral analysis. RESULTS: The group demonstrated a modest mean conditioning effect, indicated by an average reduction in resting heart rate from 81 +/- 16 to 75 +/- 12 beats/min (p = 0.03), and an increase in training METS from 2.1 +/- 0.4 to 3.3 +/- 1.1 (p < 0.0001). Overall, 15 of 20 (75%) patients demonstrated increased total and high-frequency power, and mean high-frequency power was significantly increased (3.9 +/- 1.4 vs. 4.4 +/- 1.0 ln, p = 0.05). When stratified according to the magnitude of exercise conditioning, patients achieving an increase of > 1.5 training METS demonstrated significant increases in SDNN, SDANN index, SDNN index, pNN50, total power, and high-frequency power (all p < 0.05) (see text for explanation of abbreviations). CONCLUSIONS: Exercise conditioning improves heart rate variability in cardiac patients, particularly in patients who achieve a threshold of > 1.5 training METS increase over a 12-week period. These study results are supportive of the concept that exercise training lowers the risk of sudden cardiac death via increased vagal tone, which likely beneficially alters ventricular fibrillatory and ischemic thresholds.

Aged↗
PubMed2000

Pregnancy outcome in women with primary renal disease.

BACKGROUND: The preconception and intraconception parameters that are relevant to outcome in women with underlying renal disease remain controversial. OBJECTIVES: To analyze the types and frequencies of short- and long-term (2 years after delivery) maternal and neonatal complications in 38 patients with primary renal disease (46 pregnancies), most of them with mild renal insufficiency. METHODS: Logistic regression models were formulated to predict successful outcome. RESULTS: Successful pregnancy outcome (live, healthy infant without severe handicap 2 years after delivery) was observed in 98% of the patients with primary renal disease. Factors found to be significantly predictive of successful outcome were absence of pre-existing hypertension, in addition to low preconception serum uric acid level. CONCLUSIONS: Most women with primary renal disease who receive proper prenatal care have a successful pregnancy outcome. Worse pregnancy outcome was observed in women with moderate or severe renal failure. Fitted logistic models may provide useful guidelines for counseling women with preexisting renal disease about their prospects for a successful pregnancy in terms of immediate and long-term maternal and neonatal outcome.

Female↗
PubMed1998

Compliance with hormone replacement therapy in postmenopausal women. A comparative study.

OBJECTIVE: To assess compliance with hormone replacement therapy in postmenopausal women. METHOD: Two groups were compared prospectively: 100 women who sought treatment for menopausal symptoms, and 82 women who had undergone a total abdominal hysterectomy with bilateral salpingo-oophorectomy and were using estrogen replacement therapy. RESULTS: Compliance rates after 6 months were 81.0% and 84.1% in the two groups, respectively, and after 12 months, 73.0% and 80.5%. CONCLUSIONS: The high rates are attributed to our investment in patient education of the benefits of treatment and repeated and close follow-up.

Adult↗
PubMed1996

Heart rate variability reproducibility and stability using commercially available equipment in coronary artery disease with daily life myocardial ischemia.

Heart rate variability (HRV) appears to be a strong predictor of death. The reproducibility of HRV measurements in patients with stable coronary artery disease (CAD) who have daily life myocardial ischemia, however, is unknown. Thirty patients with stable CAD (25 men and 5 women; aged 62 +/- 8 years) with daily life ischemia were studied with 2 consecutive 24-hour Holter monitoring recordings. Intra- and interobserver reproducibility of the HRV measures was high, with correlations ranging from 0.990 to 0.999 (p < 0.0001). Strong correlations between time and frequency domain HRV measures were observed (range 0.912 to 0.963; p < 0.0001). Both the frequency and duration of ischemia, measured by ST change, varied significantly by day for each patient (s = 155.5; p < 0.0001; s = 232.5, p < 0.0001, respectively). Correlations for HRV measurements between days remained high (range 0.871 to 0.983; p < 0.0001), despite stratification by magnitude of daily ischemia. Thus, 24-hour HRV measurements are stable in CAD patients with daily life myocardial ischemia over a short period, despite varying magnitudes of daily ischemia. These results support the use of HRV as a clinical tool and an outcome measure in future CAD intervention studies using commercially available equipment.

Activities of Daily Living↗
PubMed1996

Circadian variation of ambulatory myocardial ischemia. Triggering by daily activities and evidence for an endogenous circadian component.

BACKGROUND: The morning peak in myocardial ischemia has been related to diurnal variations in physical and mental activities and to postural changes upon awakening. This study assesses (1) the effects of exogenous activity triggers at different times of the day and (2) the contribution of an endogenous (ie, activity- and posture-independent) circadian vulnerability for ambulatory ischemia. METHODS AND RESULTS: Sixty-three stable coronary artery disease patients underwent ambulatory ECG monitoring and completed a structured diary assessing physical and mental activities. During 2519 hours of observation, a morning increase in ischemia coincided with increases in physical and mental activities, and an evening decrease in ischemia coincided with a decline in activities. During the morning, ischemic versus ischemia-free periods were more likely to occur with high levels of physical activity (P < .001). High physical activity triggered ischemia to a lesser but still significant extent (P < .05) in the afternoon but not in the evening (P = NS). High levels of mental activity triggered ischemia significantly during the morning (P < .04) and evening (P < .04) but not in the afternoon. When a residualized score procedure was used to correct ischemic time for each patient's simultaneously measured activities, for hourly heart rates, or for activity-related heart rate fluctuations, the circadian variation in ischemia was still observed (P < .001), with a peak at 6 AM. A significant increase in ischemia occurred immediately after awakening (P < .05), but activity-adjusted increases in morning ischemia persisted (P < .05) for 2 hours after awakening. CONCLUSIONS: Exogenous factors (physical and mental activities) are most potent as triggers of ischemia during the morning hours, and the postural change after awakening contributes to the morning increase in ischemia. There is also evidence for an endogenous, activity-independent circadian influence on ischemic susceptibility that is independent of exogenous factors and that sustains the increase in ischemia upon awakening.

Activities of Daily Living↗
PubMed1994

Low dose estrogen replacement therapy in early postmenopausal women effect on urinary magnesium and calcium: creatinine ratios.

The purpose of this study was to investigate whether treatment for prevention of osteoporosis by means of postmenopausal hormone replacement therapy (HRP) and daily exercise, had any effect on ratios of urinary calcium:creatinine (Ca:Cre) and magnesium:creatinine (Mg:Cre). A group of 33 early postmenopausal women (menopause onset 12-18 months previously), mean age 49.12 years, were treated during 6 months with low doses of transdermal estrogen (Estraderm TTS 25 micrograms, Ciba-Geigy) opposed by oral progestogen (Duphaston 10 mg, 10 days every month), and daily exercise (walking for 1 hour). Despite HRT's statistically significant lowering effect on Ca:Cre and Mg:Cre ratios, these returned to pretreatment levels 6 months after withdrawal from HRT. The mechanism by which HRT affects magnesiuria and calciuria is discussed.

Administration, Cutaneous↗
PubMed1993

The effect of estrogen replacement therapy on platelet aggregation and adenosine triphosphate release in postmenopausal women.

OBJECTIVE: To evaluate the effect of hormone replacement therapy on platelet function in postmenopausal women. METHODS: In 51 postmenopausal women, platelet aggregation and adenosine triphosphate (ATP) release were studied before and after estrogen and progestogen treatment and compared with that in untreated patients. An incubation study evaluated platelet function after incubation with estrogen and progestogen. RESULTS: Significant decreases in adrenaline-induced platelet aggregation (P < .01) and ATP release (P < .02) were observed 3 months after initiation of estrogen replacement. Patients receiving replacement regimens consisting of estrogen opposed by progestogen or progestogen alone showed nonsignificant changes in platelet aggregation and release. The most pronounced decrease in platelet function in the incubation assay was detected after incubation with estrogen plus progestogen. Results were similar in the spontaneous- and surgical-menopause patients. CONCLUSION: Estrogen replacement therapy may inhibit the atherosclerotic process by suppressing platelet function.

Adenosine Triphosphate↗
PubMed1991

Effect of sex hormones on human T cell activation by concanavalin A.

The effect of sex hormones on concanavalin A (Con A)-activated human T cells was studied. We show that neither 17 beta-estradiol (E2) nor progesterone, in concentrations of up to 10(-6) M, alters the proliferative response of peripheral-blood mononuclear cells (PBMC) of healthy postmenopausal women. Furthermore, the hormones had no effect on the composition of T cell populations and on the expression of activation markers. We extended our study to a unique T cell population that is characterized by the ability to form rosettes with human erythrocytes, following Con A activation (designated autorosette-forming cells; ARFC) and known to manifest suppressive activity. Indeed, the in vitro addition of E2 (neither progesterone nor testosterone) to Con A-stimulated PBMC brought an about 2- to 4-fold increase in the frequency of ARFC. Tamoxifen, an antiestrogen drug, reduced the frequency of estrogen-stimulated ARFC to the original low level. Furthermore, the inhibitory effect of growth medium from ARFC cultures originally stimulated with Con A + E2 was found to be higher than that of ARFC cultures originally stimulated with Con A alone.

Concanavalin A↗
PubMed1990

Frequency and activity of autorosette forming cells in Con-A activated PBL from women with hyperplasia or carcinoma of the endometrium--possible role of estrogens.

In a previous study we showed that endometrial carcinoma (EC) patients have a T cell deficiency manifested in a reduced ability to be stimulated in vitro by PHA and to produce IL-2. In an attempt to understand the mechanism responsible for this alteration we present in this paper a study on T cells characterized by the ability to form rosettes, with human erythrocytes, following Con-A activation (designated auto-rosette forming cells--ARFC). These cells are also known to manifest suppressive activity. We show that the frequency of ARFC in con-A activated peripheral blood leukocytes (PBMC) of EC patients is significantly (2-5 fold) higher than that of healthy age-matched controls or that of patients with stage--I colon or vaginal cancer. Endometrial carcinoma is known to be associated with long term exposure to estrogens unopposed by progestins. Examining the possible role of estrogens in increasing the frequency of ARFC from EC patients, we found that in vitro addition of estradiol to Con-A stimulated PBMC from healthy donors increased the frequency of ARFC to levels found in EC patients. Tamoxifen, an anti estrogen drug, reduced the frequency of the estrogen stimulated ARFC to the original low level. Our results suggest a dual role for estrogen in carcinogenesis as well as in immunomodulation.

Concanavalin A↗
PubMed1989

Premature separation of placenta in a patient with idiopathic thrombocytopenic purpura.

The most common autoimmune hemolytic disorder encountered during pregnancy is idiopathic thrombocytopenic purpura. Premature separation of the placenta is one of the most serious complications in the second half of pregnancy. Since the association of the two is not known, the aim of the present paper is to present such a case and to draw the attention of the obstetrician to this possibility.

Abruptio Placentae↗
PubMed1985

Effects of verapamil and bepridil on occlusion and reperfusion arrhythmias in the canine heart.

The effects of verapamil and bepridil on occlusion and reperfusion ventricular arrhythmias including ventricular fibrillation (VF) were studied in a canine model. The control group consisted of 27 dogs. 30 dogs received intravenous verapamil (0.2 mg/kg/3 min followed by a continuous infusion of 0.01 mg/kg/min for 15 min). 18 dogs received bepridil (0.5 mg/kg/min for 10 min). The left anterior descending coronary artery was occluded in one step 8 min after the commencement of verapamil administration and 5 min after the termination of bepridil infusion. The incidence of ventricular arrhythmias during the occlusion period was 14 (VF, 5/14), 13 (VF, 0/13) and 14 (VF, 9/14) in the control, verapamil and bepridil groups, respectively. The frequencies of reperfusion VF were 8/24 (33%), 4/30 (13.3%) and 0/13 (0%), respectively. It was concluded that (a) verapamil effectively prevents occlusion but not reperfusion VF and (b) bepridil has an arrhythmogenic effect in the ischemic canine heart but reduces the incidence of reperfusion VF.

Animals↗