Left ventricular hypertrophy in diabetic rodents is not related to left ventricular endothelin-1 mRNA expression and is prevented by insulin therapy

Elevated plasma endothelin-1 [ET-1] levels in both normotensive diabetic patients and streptozotocin [STZ]-induced diabetes have been reported before. ET-1 has been demonstrated to have a potent hypertrophic effect in cultured ventricular [LV] myocytes however, there is noevidence of altered ET1 production in the hypertrophied heart. Recent studies suggest that ovation in local LV expression of ET-1 mRNA may be associated with morphological and dynamic changes in diabetes mellitus [DM]. To test local LV ET1 mRNA expression in both insulin treated and nontreated diabetic animal models, explore its possible relation to LV hypertrophy [LVH], and assess some hemodynamic parameters in this pathophysiologic state. Results were compared to those obtained from normal healthy control animals of the same strain. DM was induced in 2 groups [dm-8 and dm-0] of 3 month Sprague Dawley rats [n=20 per group, blood glucose 693 +/- 101 and 592 +/- 87 mg/dl] by intraperitoneal injection of STZ [60 mg/Kg]. Insulin therapy was given to rats of dm-8 group. Rats of group dm-0 were left without treatment. Findings were compared to normal Sprague Dawley controls [n=11, blood glucose 125 +/- 20 mg/dl]. All were followed for 8 weeks, and a terminal hemodynamic stud] was performed with mean aortic flow [MAF, ml/min], mean aortic pressure [MAP, mmHg], heart rate [bpm]. Systemic arterial resistance [SAR, units] was derived. LV tissue was harvested at -80 dgree C. LV wet weight was determined and LV weight / body weight index [LVwgt./b.wgt., mg/gm] was derived. Following dot-blot autoradiographic analysis and quantitative densitometry. ET-1 mRNA was expressed as a ratio of control G3PDH mRNA. The MAP did not reveal significant difference in the 3 groups. MAP was significantly reduced in both diabetic groups with significantly reduced SAR in untreated diabetic rats. Untreated diabetic rats developed significant LVH compared to treated diabetics and normal controls. LVET1 mRNA expression was significantly greater in insulin treated group. No significant difference between normal and untreated diabetics regarding their LV mRNA encoding for ET1. In the lab animal model, IDDM was associated with LVH apparently secondary to volume overload due to systemic vasodilation. This LVH was prevented by insulin treatment. However, insulin as a growth factor increased LV ETlmRNA expression. This wrrants further research particularly in type II DM which is usually associated with hyperinsulinemia

Dobutamine-transesophageal echocardiography versus dipyridamole thallium-201 scintigraphy for assessment of myocardial viability

Dipyridamole Thallium-201 scintigraphy have been widely used to differentiate between scar tissue and viable but not functioning myocardium and showed superiority over dobutamine stress echo-cardiography. The development of transesophageal echocardiogram [TEE] may overcome many of transthoracic limitations. To compare dobutamine stress TEE and Dipyridamole thallium scintigraphy in detection of myocardial viability. The study included 27 patients with coronary artery disease [CAD] and severe segmental wall motion abnormalities [SWMA] on resting echocardiogram who were scheduled for revascularization either through angioplasty or bypass surgery [CABG]. Dobutamine-TEE and dipyridamole thallium scintigraphies were done within 5 to 7 days before revascularization. Post-revascularization resting echocardiography was done 14 to 21 days to assess any improvement of SWMA as a sign of myocardial viability. Although the sensitivity of dobutamine TEE to detect myocardial viability was higher than that of thallium scintigraphy [89% vs. 72% respectively] but it did not reach statistical significance [P=0.06]. However, the specificity of TEE was significantly higher than that of scintigraphy [83% vs. 67%, P=0.04] and the total diagnostic accuracy of dobutamine TEE to detect myocardial viability was significantly higher than that of dipyridamole thallium scintigraphy [88% vs. 71% p = 0.05]. In the presence of severe SWMA, dobutamine TEE could detect myocardial viability more frequently than dipyridamole thallium scintigraphy

Pro-collagen peptides in essential hypertension and its relation to cardiac structure and functions before and after antihypertensive therapy

A significant increase in fibrillar collagen content, type I and type III, has been observed in the cardiac ventricles of both animals and humans with arterial hypertension. The serum concentrations of procollagen type I carboxy terminal peptide [PIP] and procollagen type III amino terminal peptide [PIIIP] have been proposed as a useful markers of collagen types I and III synthesis. We evaluated fibrogenic activity in patients with essential hypertension by measuring serum concentrations of PIP and PIIIP as markers of tissue synthesis of collagen type I and type III, and its relation to parameters of left ventricular [LV] structure and functions in those patients. The effect of treatment with ACE inhibitor [captopril] for 6 months on serum concentrations of both PIP and PIIIP was also studied. The study included 79 patients with newly diagnosed mild to moderate hypertension and 50 normotensive subjects. Ages ranged between 35 to 60 years. Careful blood pressure measurement was obtained in all subjects. M-mode, two dimensional, and pulsed Doppler were performed to get baseline LV anatomy and function. Serum PIP and PIIIP were measured by radioimmunoassay. Both echocardiography and biochemical studies were repeated for all hypertensives after 6 months treatment with captopril. Serum PIP and PIIIP were significantly higher in hypertensive patients compared with normotensive subjects. PIP was 258 +/- 57mg/L in hypertensives vs. 167 +/- 70mg/L in normotensives. PIIIP was 3.73 +/- 2.2mg/L in hypertensives vs. 1.9 +/- 1.4mg/L in normotensives. In addition, PIP and PIIIP were significantly higher in hypertensives with LV hypertrophy [LVH] than those with normal LV mass. Moreover, serum concentration of PIP was directly correlated with LV mass index. On the other hand, PIIIP was inversely correlated with VE/VA ratio. After treatment, significant echocardiographic and biochemical improvements were observed. LVH regressed in 13 out of 68 patients [19%], LV mass index was normalized in 17 out of 58 patients [29%], and diastolic dysfunction was normalized in 10 out of 44 patients [23%]. Serum PIP and PIIIP were significantly reduced in hypertensives. Serum concentrations of both PIP and PIIIP are significantly increased in hypertensives and this was more pronounced among patients with LVH. This was correlated with structural and functional LV changes in the form of LVH and diastolic dysfunction. All changes demonstrated significant improvement after treatment with captopril

Effect of insulin on plasma endothelin-I and arterial blood pressure in normal and diabetic rats

This study was designed to compare the plasma level of Endothelin - I and the arterial blood pressure in both normal and streptozotocin induced diabetic rats and to study the effect of insulin treatment on the two tested parameter in normal and diabetic rats. Sixty male rats were used and divided into 5 groups: group [1] [normal rats, served as control A], Group 2 [normal rats treated with insulin for 8 weeks], group 3 [diabetic rats served as control B],Group 4 [diabetic rats treated with insulin for 4 weeks] and Group 5 [diabetic rats treated with insulin for 8 week]. Our results showed that the mean arterial blood pressure was significantly decrease in diabetic rats, while their plasma level of Endothelin- I was higher than the non diabetic rats. Insulin administration to normal and diabetic rats produced significant rise in both tested parameters

Assessment of pulmonary functions in passive smokers in comparison to control

The purpose of the present study was to evaluate the effects of passive smoking on the occurrence of some respiratory symptoms and on pulmonary functions. Two groups of normal subjects [males and females] have been examined, 245 subjects each. The study group was exposed passively to cigarette smoking and the control group was unexposed. The occurrence of respiratory symptoms [cough and phlegm were evaluated by a questionnaire and the pulmonary function by a battery of tests [FVC, FEV1, PEFR, MMEF, and FEV25 -75]. The prevalence of cough and phlegm was significantly higher prevalence of cough and phlegm was significantly higher among exposed group. Also the most of pulmonary function indices were significantly reduced in the exposed group. The results illustrates the detrimental effects of passive cigarette smoking on exposed subjects