Triple papillary fibroelastomas in an asymptomatic patient

Papillary fibroelastoma is the third most common type of primary cardiac tumour. Even though the majority of patients with these tumours are asymptomatic, they may present with embolic phenomena, syncope and death. This report describes a patient with papillary fibroelastomas affecting all three cusps of the aortic valve, with accompanying transoesophageal echocardiography and images of surgical specimens of the tumours.

Assessment of the stability of pesticides during cryogenic sample processing. 1. Apples

An assessment of the stability of a large number (106) of pesticides and related compounds during the cryogenic sample processing of apples has been undertaken. For the first time the procedure included an assessment of the losses during the freezing of the fruits, prior to processing. The stability of each pesticide during processing was assessed by comparing the mean recovery for the laboratory-spiked samples with the mean "survival" of the pesticides in cryogenically processed samples. The results clearly demonstrate that the vast majority, 94 of 106, of pesticides were stable during cryogenic processing. Of particular importance was that losses of several pesticides [bitertanol (95%), heptenophos (50%), isofephos (40%), and tolylfluanid (48%)] reported to occur during ambient processing of apples did not occur during cryogenic processing. Losses of dichlofluanid (54%), chlozolinate (22%), and etridiazole (40%), previously reported to occur during ambient processing of apples, were reduced to barely significant levels (10, 17, and 14%, respectively) by cryogenic processing. Small apparent losses for a few of the compounds were attributable to analytical and sample handling difficulties, rather than to losses during processing, and need further investigation.

Caffeine and stress: implications for risk, assessment, and management of hypertension

Caffeine use is widespread, and its consumption increases during periods of stress. Caffeine raises blood pressure by elevating vascular resistance, and this effect is larger and more prolonged in hypertensive patients than in normotensive. The pressor response to caffeine occurs equally in persons at rest and under stress. The elevated baseline pressures of the hypertensive patient are therefore increased by both caffeine and stress, potentially leading to undesirably high pressures. Such combined effects on blood pressure may potentially confound the evaluation of hypertension, and possibly reduce the effectiveness of antihypertensive therapy. These effects are not abolished by pharmacologic tolerance to caffeine, as tolerance may not be complete with daily intake. The contribution of caffeine's effects to the development of hypertension warrants continued study, and caffeine use by patients merits consideration in terms of assessment and management of this disorder.

Hypertension risk status and effect of caffeine on blood pressure

We compared the acute effects of caffeine on arterial blood pressure (BP) in 5 hypertension risk groups composed of a total of 182 men. We identified 73 men with optimal BP, 28 with normal BP, 36 with high-normal BP, and 27 with stage 1 hypertension on the basis of resting BP; in addition, we included 18 men with diagnosed hypertension from a hypertension clinic. During caffeine testing, BP was measured after 20 minutes of rest and again at 45 to 60 minutes after the oral administration of caffeine (3.3 mg/kg or a fixed dose of 250 mg for an average dose of 260 mg). Caffeine raised both systolic and diastolic BP (SBP and DBP, respectively; P<0.0001 for both) in all groups. However, an ANCOVA revealed that the strongest response to caffeine was observed among diagnosed men, followed by the stage 1 and high-normal groups and then by the normal and optimal groups (SBP F(4),(175)=5.06, P<0.0001; DBP F(4,175)=3.02, P<0.02). Indeed, diagnosed hypertensive men had a pre-to-postdrug change in BP that was >1.5 times greater than the optimal group. The potential clinical relevance of caffeine-induced BP changes is seen in the BPs that reached the hypertensive range (SBP >/=140 mm Hg or DBP >/=90 mm Hg) after caffeine. During the predrug baseline, 78% of diagnosed hypertensive men and 4% of stage 1 men were hypertensive, whereas no others were hypertensive. After caffeine ingestion, 19% of the high-normal, 15% of the stage 1, and 89% of the diagnosed hypertensive groups fell into the hypertensive range. All subjects from the optimal and normal groups remained normotensive. We conclude that hypertension risk status should take priority in future research regarding pressor effects of dietary intake of caffeine.

Gender-related effects on metoprolol pharmacokinetics and pharmacodynamics in healthy volunteers

OBJECTIVE

To determine whether there are gender-specific differences in the pharmacokinetics and pharmacodynamics of metoprolol enantiomers.

METHODS

Twenty normal volunteers (10 men and 10 women) received 100 mg oral metoprolol tartrate twice daily for a total of nine doses. Pharmacokinetics and pharmacodynamics were studied after the last dose. Subjects also completed a control pharmacodynamic study; the order of drug and control studies was randomized. Measurements of heart rate and systolic blood pressure were obtained during peak submaximal bicycle exercise testing. (R)-Metoprolol and (S)-metoprolol concentrations were determined by stereospecific HPLC. The percentage difference in exercise heart rate and systolic blood pressure (metoprolol versus control), and (R)- and (S)-metoprolol plasma concentrations were comodeled.

RESULTS

Men and women showed stereoselective pharmacokinetics; (S)-metoprolol concentrations were significantly greater than those for (R)-metoprolol for both groups. Women had greater drug exposure than men (higher maximum concentration and area under the plasma concentration-time curve). No differences were observed between genders with respect to elimination half-life. Females had a greater reduction in exercise heart rate and systolic blood pressure; however, the area under the effect curve was significantly greater for heart rate only. Pharmacodynamic data were best fitted by the Hill equation with the effect site in the central compartment. The fitted maximum effect and the concentration at one-half of the maximum effect for heart rate and systolic blood pressure did not differ between men and women (P > .20).

CONCLUSIONS

Gender-related differences exist in the pharmacokinetics of metoprolol enantiomers, resulting in greater drug exposure in female subjects. However, concentration-effect relationships did not differ between men and women. Therefore the observed differences in drug effects were the result of gender-specific differences in metoprolol pharmacokinetics.

Insulin-induced vasodilatation of internal carotid artery

The increase in leg and forearm blood flow induced by insulin could be secondary to its metabolic effect on glucose uptake. We therefore investigated whether insulin causes vasodilation of the internal carotid artery, since the brain is not dependent on insulin for glucose uptake, to demonstrate that the vasodilatory effect of insulin is primary and independent of its metabolic effect. Internal carotid artery diameter was continuously monitored using a 7.5-MHz transducer linked to an Acuson XP10 ultrasonograph (Mountainview, CA) during infusion of 125 mL 10% dextrose mixed with 3 U regular insulin and 5 mmol potassium chloride over 1 hour. The internal carotid artery diameter increased progressively with time from a mean of 5.4+/-1 mm to 5.7+/-1 mm at 15 minutes, 5.9+/-1.1 mm at 30 minutes, 6+/-1.1 mm at 45 minutes, and 6.1+/-1.1 mm at 60 minutes (P < .05), an increase of 13% over baseline. Glucose was maintained between 93 and 106 mg/dL, and insulin increased from 15+/-14 microU/mL and was maintained between 34 and 47 microU/mL. There was no change in mean arterial blood pressure (MABP) or heart rate during the infusion. We conclude that insulin dilates the internal carotid artery consistently at physiological concentrations, probably independently of glucose uptake by the brain. Alterations in this effect of insulin may be of relevance in the pathogenesis of abnormalities of cerebral blood flow in type 1 and type 2 diabetics as described by our group previously.

Grapefruit juice has minimal effects on plasma concentrations of lovastatin-derived 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors

OBJECTIVE

To evaluate the effect of regular-strength grapefruit juice, a cytochrome P4503A4 (CYP3A4) inhibitor, on the pharmacokinetics of a commonly prescribed regimen of oral lovastatin.

METHODS

In a randomized crossover study, 16 healthy subjects received a single 40 mg dose of lovastatin in the evening after each consumed an 8-ounce glass of regular-strength grapefruit juice or water with breakfast for 3 consecutive days. The effect of the same grapefruit juice and water regimen on the pharmacokinetics of midazolam (2 mg oral dose given 1 hour after the third day of grapefruit juice and water) was used as a positive control in the same subjects. Plasma concentrations of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors were determined by an enzyme inhibition assay, and concentrations of lovastatin, lovastatin acid, and midazolam were determined by liquid chromatography-tandem mass spectrometry.

RESULTS

The area under the plasma concentration-time profiles (AUC) and maximum plasma concentrations (Cmax) of HMG-CoA reductase inhibitors increased slightly (-30% for each) after consumption of grapefruit juice. Similar effects on AUC and Cmax (approximately 40% increase for each) were noted after analysis of samples of hydrolyzed plasma (which converts inactive lactones to active hydroxy acid species). The AUC and Cmax values for lovastatin approximately doubled in the presence of grapefruit juice, whereas the same parameters for lovastatin acid increased 1.6-fold. Grapefruit juice caused the AUC for midazolam to increase by a factor of approximately 2.4.

CONCLUSIONS

Daily consumption of a glass of regular-strength grapefruit juice has a minimal effect on plasma concentrations of HMG-CoA reductase inhibitors (approximately 30% to 40% increase) after a 40 mg evening dose of lovastatin.

Vasodilatory effects of troglitazone improve blood pressure at rest and during mental stress in type 2 diabetes mellitus

The present study examined the hemodynamic mechanisms of blood pressure (BP) lowering by troglitazone in patients with type 2 diabetes mellitus (DM) at rest and during a mental arithmetic test (MAT). Twenty-two patients with DM with normal to high-normal BP and 12 controls matched for age, gender, glucose tolerance, and BP were studied. DM subjects showed significantly higher systolic BP response during MAT than controls (157 versus 139 mm Hg; P<0.01). All 22 DM patients and 5 of 12 controls had systolic BP >140 mm Hg during MAT. Heart rate and diastolic BP were not significantly different between the 2 groups. The DM group was then randomized to receive troglitazone (n=10; 400 mg/d) or glyburide (n=12; 20 mg/d). MAT was repeated after 6 months of treatment. Both treatments reduced glucose equally (-1.7 mmol/L for troglitazone and -1.5 mmol/L for glyburide), but only troglitazone reduced insulin (-15 microU/mL; P<0.001) and C-peptide (-0.9 ng/mL; P<0.02) levels. Troglitazone significantly reduced BP at baseline (P<0.05) and systolic BP response to MAT (P<0.01), whereas glyburide did not affect BP at baseline or during MAT. Stroke volume and cardiac output did not change with either drug, but troglitazone decreased peripheral vascular resistance (-112 dyne. s. cm(-5); P<0.05). Improved insulin resistance rather than an improved glycemic control is associated with lower resting and stress BP values in patients with DM. A reduction in vascular resistance may be a primary hemodynamic mechanism of the manner in which troglitazone lowers BP. Insulin sensitizers may offer potential therapeutic advantage in subjects with DM with elevated BP.

Patterns of prescribing ACE inhibitors after myocardial infarction

We attempted to determine physician prescribing patterns of angiotensin-converting enzyme (ACE) inhibitors in patients who experienced a myocardial infarction, stratified by left ventricular function. We retrospectively reviewed drug therapy at discharge in 534 patients to assess prescription of ACE inhibitor therapy, including dosage. Thirty-four percent of patients were discharged taking an ACE inhibitor, of whom only 11% received recommended dosages. The drugs were prescribed more often for patients who had an ejection fraction below 40% than for those with an ejection fraction of 40% or above (54% vs 28%, p<0.05). We conclude that ACE inhibitors are underprescribed for patients who experienced a myocardial infarction, illustrating the gap between clinical research and clinical practice, and the need for programs to ensure optimal medical management.

Estrogen improves abnormal norepinephrine-induced vasoconstriction in postmenopausal women

OBJECTIVE

An exaggerated blood pressure response to mental stress in postmenopausal women has been reported but the underlying mechanism is not clear. In the present study, we examined the role of estrogen in the blood pressure response to mental stress.

SUBJECTS AND METHODS

Hemodynamic responses to mental stress and constrictor responses to norepinephrine were compared in 18 premenopausal (mean +/- SD age 33 +/- 5 years), 22 postmenopausal women (62 +/- 7 years) and 13 postmenopausal women with estrogen replacement therapy (58 +/- 8 years). Premarin was infused in 10 postmenopausal women to determine whether estrogen attenuates norepinephrine-induced vasoconstriction. The hemodynamic responses to a standard mental arithmetic test were measured. Norepinephrine (12.5, 25, 50, 100 ng/min) was infused at 0.5 ml/min for 5 min via the dorsal hand vein. Norepinephrine (100 ng/min) combined with premarin (200 microg/min) was infused into the dorsal hand vein of postmenopausal women. Changes in venous diameter were measured by ultrasonography using a 7.5 MHz transducer.

RESULTS

All study subjects were healthy, normotensive and had normal lipid profiles. The postmenopausal women showed a significantly greater blood pressure response to the mental arithmetic test than the premenopausal women or those taking estrogen replacement therapy (P < 0.01). Norepinephrine induced significant dose-dependent vasoconstriction in all three groups (P < 0.001). The postmenopausal women showed significantly greater constriction in response to norepinephrine than the premenopausal women and those taking estrogen replacement therapy (P = 0.02). Premarin significantly attenuated the norepinephrine-induced vasoconstriction in the postmenopausal women (P< 0.001).

CONCLUSION

Healthy, normotensive postmenopausal women showed an exaggerated blood pressure response to mental stress. An increased vasoconstriction in response to norepinephrine and loss of estrogen-mediated vasodilation may contribute to the increased blood pressure response to stress in postmenopausal women without estrogen replacement therapy.

Effect of gender differences and estrogen replacement therapy on vascular reactivity

The incidence of cardiovascular disease is lower in premenopausal women compared with men; following menopause, the risk of mortality from cardiovascular disease increases in females. Postischemic dilatation of the brachial artery has been used previously as an index of endothelium-mediated vasodilation. Using this index, we examined a group of premenopausal and postmenopausal women, some of whom were on estrogen replacement therapy (ERT). All subjects were normotensive (blood pressure [BP] <140/90 mm Hg) and normoglycemic (blood glucose, <100 mg/dL). Fourteen healthy women (mean age, 27 +/- 0.8 years; mean total cholesterol, 174 +/- 6.7 mg/dL) and fourteen healthy men (mean age, 26 +/- 1.4 years; mean total cholesterol, 181 +/- 7.2 mg/dL) were investigated. Nineteen postmenopausal women were also examined; 11 were on ERT (mean age, 55 +/- 2.1 years; mean total cholesterol, 213 +/- 6.6 mg/dL) and eight were not on ERT (mean age, 60 +/- 3.6 years; mean total cholesterol, 222 +/- 14.4 mg/dL). Ischemia was induced by inflating a cuff over the forearm to a pressure of 40 mm Hg above systolic for 5 minutes. Doppler ultrasonography (Acuson [Mountain View, CA] 128XP/10c ultrasonograph with a 7.5-MHz linear array transducer) was used to measure the brachial artery diameter before inflation and 15 seconds and 45 to 60 seconds following cuff deflation. Flow-mediated dilatation (FMD%) and hyperemia were defined as the percentage increase over basal diameter and basal flow, respectively. Postischemic median dilatation in men was 4.20% (interquartile range, 2.13% to 5.56%) and 11.48% (interquartile range, 8.70% to 14.29%) in age-matched premenopausal women (P < .01). For women on ERT, the postischemic median dilatation was 8.11% (interquartile range, 6.01% to 11.60%), as compared with 2.82% (interquartile range, 1.32% to 3.28%) for women without ERT (P < .01). Premenopausal women showed significantly greater dilatation after ischemia than postmenopausal women without ERT (P < .0001). Hyperemia was similar in all groups. These findings show that postischemic vasodilation of the brachial artery is greater in premenopausal women versus age-matched men; it is decreased in postmenopausal women, and ERT restores it toward normal. The pathophysiology underlying the diminution in postischemic dilatation may be relevant to atherogenesis and coronary artery disease (CAD).

Hypothalamic-pituitary-adrenocortical responses to psychological stress and caffeine in men at high and low risk for hypertension

OBJECTIVE

This study examined pituitary-adrenocortical responses to dietary doses of caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coffee), alone and combined with behavioral stress, in men at high risk versus low risk for hypertension. A randomized, double-blind, caffeine-placebo crossover design was used.

METHOD

Adrenocorticotropic hormone (ACTH) and cortisol levels in plasma were assessed at rest and in response to 60-minutes of continuous work on a mental stressor (arithmetic) and a psychomotor task (reaction time) on four test sessions held on separate days.

RESULTS

Tasks alone caused greater ACTH and cortisol increases in high risk men than in the low risk group. Caffeine alone elevated ACTH and cortisol in both groups, with more immediate responses in the high risk group. Both groups showed significant ACTH and cortisol responses to caffeine plus tasks, with the high risk group showing more persistent elevations. The high risk group also showed the highest levels of ACTH and cortisol after caffeine plus tasks.

CONCLUSIONS

These findings demonstrate for the first time the combined effects of caffeine plus stress on ACTH and demonstrate greater corticosteroid effects in hypertension-prone men. As such, they may have implications for the dietary use of caffeine during periods of stress and in those at risk for hypertension.

The effects of gender on adrenergic receptor responsiveness

This study was conducted to determine whether gender differences exist in adrenergic receptor sensitivity and baroreflex response. Adrenergic receptor sensitivity was assessed by administering sequentially increasing intravenous doses of phenylephrine and isoproterenol. Baroreflex sensitivity was determined from the slope of pulse intervals plotted against phenylephrine-induced rise in systolic blood pressure (SBP). Drug-induced changes in heart rate, blood pressure, and brachial artery diameter were measured and statistically compared. Women required a lower infusion rate of phenylephrine to increase SBP by 20 mmHg from baseline. There were no statistically significant gender-related differences in baroreflex sensitivity. The dose of isoproterenol needed to increase heart rate by 25 beats per minute from baseline also did not differ significantly between groups. Percent changes from baseline in brachial artery diameters in response to phenylephrine also were similar between groups. These data suggest that women may have greater alpha-adrenergic receptor sensitivity than men, whereas beta1-adrenergic receptor sensitivity is similar between genders. A trend toward a greater baroreflex sensitivity in men than in women was also observed. This study also provides evidence for a possible relationship between adrenergic receptor sensitivity and baroreflex sensitivity.

Insulin-mediated venodilation is impaired in patients with high cholesterol

Recently we have reported that insulin attenuates norepinephrine (NE)-induced vasoconstriction via a cyclic GMP-NO synthase pathway. Because hypercholesterolemia has been associated with abnormal endothelial function, we investigated whether insulin-mediated vasodilation is impaired in hypercholesterolemia. To assess vasoreactivity, NE (12.5, 25, 50, and 100 ng/min), NE (100 ng/min) combined with insulin (8, 16, 24, and 32 microU/min), and NE (100 ng/min) combined with sodium nitroprusside (0.01, 0.1, 1, 10, and 100 ng/min) were infused into dorsal hand veins. Changes in venous diameter were measured by ultrasonography, using a 7.5-MHz transducer. Twenty-two healthy, normotensive hypercholesterolemic subjects (HC; mean total cholesterol 6.93 mmol/L, HDL 1.45 mmol/L, LDL 4.81 mmol/L) and 18 age-matched normal control subjects (NC; mean total cholesterol 4.81 mmol/L, HDL 1.16 mmol/L, LDL 3.18 mmol/L) were studied. All HC had normal glucose tolerance test results. Baseline vein diameters were similar between groups, and the vasoconstrictor response to NE was not significantly different between HC and NC. Insulin significantly attenuated NE-induced vasoconstriction in NC but not in HC (P<0.01). Both groups were able to venodilate with sodium nitroprusside. To investigate the effects of cholesterol reduction on vascular reactivity, venoreactivity studies were repeated in 12 HC after treatment with 20 to 40 mg/d lovastatin for 6 weeks. There were no significant venoreactivity changes with the treatment. Plasma LDL cholesterol concentration was inversely correlated to venodilator effect of insulin (r=-0.42, P<0.02). In conclusion, insulin-mediated vasodilation is impaired in patients with high cholesterol. Absence of normal insulin-mediated but not sodium nitroprusside-induced venodilation in hypercholesterolemia suggests that insulin-mediated vasodilation is endothelium dependent.

Vasoreactivity in pre- and postmenopausal women: evaluation by pharmacodynamic modeling

Postmenopausal women experience an increase in cardiovascular mortality and morbidity compared with their premenopausal counterparts. This study was undertaken to develop a pharmacodynamic model to determine whether vascular reactivity in postmenopausal women differed from that in premenopausal women. Eleven subjects in each group were recruited. Graded doses of norepinephrine and insulin were infused via the dorsal hand vein. Venous diameter was measured by ultrasound. Dosage and venous diameter were fit to a Hill-type pharmacodynamic model in which norepinephrine acts as a vasoconstrictor and insulin counteracts varying fractions of norepinephrine constriction. Fitted pharmacodynamic parameters for norepinephrine did not differ uniformly between groups, but at norepinephrine infusion rates between 14 and 46 ng/mL, postmenopausal women demonstrated increased norepinephrine-induced vasoconstriction. Also, the modeled maximal response to insulin (Emaxi) was greater in premenopausal women. By stepwise linear regression, maximal response to insulin was found to be related to menopausal status and diastolic blood pressure. Postmenopausal women showed differences in vasoreactivity that may have important implications in the pathogenesis of hypertension.

Directional coronary atherectomy versus coronary angioplasty in vessels larger than 3 mm in diameter

It has been proposed that directional coronary atherectomy (DCA) should be an intervention of choice in larger vessels as one can achieve a greater minimal luminal diameter with DCA than with percutaneous transluminal coronary angioplasty (PTCA). This in turn should translate into a higher success rate and may even reduce the restenosis rate. The aim of this study was to compare DCA versus PTCA in vessels > 3 mm in diameter. One hundred fifty consecutive patients who met the inclusion criteria and had DCA were compared to 150 similarly selected PTCA patients. PTCA patients were selected from the era immediately preceding the advent of DCA so that selections bias could be excluded. All patients with ostial lesions, restenosis, vessels < 3 mm in diameter, and vessels with more than two significant lesions were excluded. Distal segments and circumflex cases were excluded as they formed a small subsegment. Both groups were similar in terms of demographic, clinical and angiographic variables. Quantitative analysis showed that the initial net gain was significantly greater in the DCA group than in the PTCA group (2.36 +/- 0.8 mm vs. 1.78 +/- 0.7 mm; p < 0.05). Residual stenosis was 11% with DCA compared to 33% with PTCA (p < 0.05). Despite these improved anatomical results the procedural success rates were similar (91.5% vs 84%). Major in hospital complications (death, acute occlusion, MI, emergency CABG, re-do) were higher in the DCA group than in the PTCA group (12% vs 6%). Clinical follow-up on 276 patients (150 DCA vs 126 PTCA) showed a 6 month clinical restenosis rate of 18% vs 28%, respectively. The incidence of re-do in 24 hours for acute occlusion was 6% for DCA and 1% for PTCA. In large-sized vessels DCA results in a lower restenosis rate. However, despite a lower incidence of residual stenosis, the complication rate tends to be higher with DCA (p < 0.05).

Compliant vs non-compliant balloons. A prospective randomized study

In this prospective randomized trial we explored the possibility of different procedural outcomes with regard to compliant (polyolefin copolymer (POC)), and non-compliant (polyethylene terapthelate (PET)) balloon materials commonly used during percutaneous transluminal coronary angioplasty (PTCA). For this purpose, 51 female and 149 male (total 200) patients were randomized to 100 compliant and 100 non-compliant balloons. Only single lesions were included in the study and patients who had PTCA for more than one lesion in different segments at different sessions were each entered separately (there were actually 49 female and 143 male patients). PTCA procedures were performed in conjunction with quantitative coronary angiographic techniques and the films were reviewed by two investigators in a blinded fashion. Statistical analysis for various procedural end-points were performed by non-paired Student t test with statistical significance being p < 0.05. There were no differences in demographic and clinical characteristics between groups. Lesion characteristics of both groups were exactly matching for vessel size, balloon size, balloon vessel ratio, minimal luminal diameter and percent stenosis of the index lesion. Similarly, minimal residual diameter, percent residual stenosis, net gain, densitometric net area gain, and maximum pressure (2.2 +/- 5 mm vs 2.1 +/- 0.6 mm, 18 +/- 17% vs 23 +/- 15%, 0.8 +/- 0.5 mm vs 0.8 +/- 0.6 mm, 48 +/- 25% vs 48 +/- 26%, 7.3 +/- 2 atm. vs 6.8 +/- 3 atm., respectively) values were not statistically different between compliant and non-compliant balloon groups. Major in-hospital complications, dissections caused by the study balloon (mostly type A and B), crossover and bail-out procedures (5 vs 3, 34 vs 32, 4 vs 3, 13 vs 14, respectively) were similar for both compliant and non-compliant balloon groups. Study balloon success rate (defined as < 50% residual stenosis or > 20% net gain in the absence of major in-hospital complications, crossovers and bail-outs) and overall procedural success rate (80% vs 74%, 90% vs 85%) were not statistically different for compliant and non-compliant balloons. In conclusion, we did not observe any statistically significant difference between compliant and non-compliant balloons in terms of immediate procedural results.

Moderately obese, insulin-resistant women exhibit abnormal vascular reactivity to stress

To define the hemodynamic implications of insulin resistance (IR), we compared 10 normotensive, insulin-resistant women who had abnormal glucose tolerance tests with 10 age-matched healthy normotensive women with normal glucose tolerance tests with respect to mental arithmetic and handgrip responses. Hemodynamic variables obtained at baseline and during stress included heart rate, blood pressure, cardiac output, and systemic vascular resistance. The IR group weighed more (84 versus 66 kg). Screening BP was similar (123/72 versus 120/68 mm Hg, P=NS) between groups although baseline diastolic BP at testing day was higher in the IR group than control group (75 versus 65 mm Hg, P<.05). The IR group showed a significantly greater increase in systolic (18% versus 10%, P<.O1) and diastolic (24% versus 12%, P<.01) blood pressure responses to mental stress than the control group. During mental stress, the control group demonstrated increased cardiac output (1.4 L/min) and decreased systemic vascular resistance (-120 dyne x s x cm[-5]), whereas IR subjects demonstrated increased systemic vascular resistance (119 dyne x s x cm(-5); group difference, P<.02) with only a small increase in cardiac output (0.5 L/min). Handgrip also caused a greater increase in systemic vascular resistance in the IR group (252 versus 64 dyne x s x cm(-5), P<.05), with a correspondingly greater increase in blood pressure than control subjects. Baseline blood pressure was correlated with weight (r=.41, P<.02) and stress blood pressure with fasting insulin (r=.51, P<.001) and glucose-to-insulin ratio (r= -.55, P<.001). We conclude that insulin resistance is associated with an exaggerated blood pressure response to stress; an enhanced vasoconstriction to stress may mediate this response. This hyperreactivity may be a marker for future hypertension in obese, normotensive, hyperinsulinemic individuals.

Effects of cholesterol reduction on BP response to mental stress in patients with high cholesterol

Impaired endothelium-dependent vascular relaxation has been reported in patients with high cholesterol (HC), but the systemic effects of elevated cholesterol on blood pressure (BP) and BP reactivity to stress have not been studied. We examined the BP response to a standard mental arithmetic test (MAT) in 37 healthy, normotensive HC subjects and 33 normal cholesterol controls (NC). Both groups had similar age, body mass index, and gender distribution. HC had slightly higher systolic BP at baseline (122 v 118 mm Hg, P < .05) than NC and systolic BP response during MAT was significantly higher in HC compared to NC (18 +/- 8 v 10 +/- 5 mm Hg, P < .05). Maximal changes in systolic BP were significantly correlated with cholesterol (R = 0.41, P < .001), whereas heart rate and diastolic BP changes were unrelated to serum cholesterol. To confirm that BP reactivity was dependent on cholesterol, MAT was repeated after treatment with 20 mg/day of lovastatin, a hepatic hydroxymethyl glutaryl coenzyme A (HMG-CoA) reductase inhibitor, for 6 weeks using a cross-over design in 26 HC subjects. Lovastatin significantly altered lipid profiles (-26% total cholesterol, +8% HDL, -34% LDL). A small decrease in systolic BP at baseline (-3 mm Hg, P = NS) and significantly lower systolic BP (-8 mm Hg, P < .05) during MAT was observed after the treatment with lovastatin. In conclusion, patients with high cholesterol had an exaggerated systolic BP response to MAT. Decreased BP reactivity during HMG-CoA reductase inhibitor therapy suggests that lowering cholesterol may have a role in the overall control of BP.

Stress-like adrenocorticotropin responses to caffeine in young healthy men

The effects of oral caffeine (3.3 mg/kg, equivalent to 2-3 cups of coffee) on plasma adrenocorticotropin (ACTH) and cortisol (CORT) were tested in 47 healthy young men at rest in a double-blind, placebo-controlled, crossover study. Following caffeine, ACTH was significantly elevated at all times from 30 min to 180 min, and CORT was elevated from 60 min to 120 min (Fs > or = 8.4, ps < 0.01). Peak increases relative to placebo were: ACTH, 33% (+5.2 pg/ml) and CORT, 30% (+2.7 micrograms/dl) at 60 min postcaffeine. The results suggest that caffeine can activate important components of the pituitary-adrenocortical response in humans during the resting state. Caffeine's known ability to increase CORT production appears at least partly due to an increase in ACTH release at the pituitary.

Caffeine and behavioral stress effects on blood pressure in borderline hypertensive Caucasian men

Caffeine in dietary amounts raises blood pressure (BP), and its use increases during work stress; however, caffeine combined with behavioral stress has not been tested in borderline hypertensive (BH) men. Accordingly, this study tested a psychomotor stressor plus caffeine (3.3 mg/kg, equivalent to 2-3 cups of coffee) using a double-blind, crossover design in 24 BH men (140/90 mmHg < or = BP < or = 160/95 mmHg) and 24 controls (BP < or = 135/85 mmHg). BH men had modestly larger BP increases to the task and showed a greater combined effect of caffeine plus the task (+15/+11 mmHg) than controls (+10/+6 mmHg). BH men maintained response to the stressor in the face of an exaggerated BP response to caffeine, suggesting that use of caffeine during behavioral stress may elevate BP in BH individuals to a clinically meaningful degree.

Dose-response effect of in vivo administration of endotoxin on polymorphonuclear leukocytes oxidative burst

In vitro, endotoxin primes polymorphonuclear leukocytes (PMNs) to respond with a greater oxidative burst. The purpose of the present study was to investigate the in vivo effect of a wide range of single endotoxin bolus doses using a rat model. PMNs were subsequently challenged in vitro with phorbol ester to produce reactive oxygen intermediates (ROI). Flow cytometric determination of ROI production by large doses induced a decrease in ROI production by the few PMNs that remained in the circulation. By 6 h after injection, ROI production had returned to basal levels after a high dose, and was still increasing after a low dose. Neutropenia occurred immediately after endotoxin injection. After 6 h, PMN counts returned to almost normal levels with a high dose, but rebound neutrophilia occurred with a small dose. In contrast to in vitro studies, in vivo injection showed a response pattern that varied widely with dose and time of observation.

Acute blood pressure elevations with caffeine in men with borderline systemic hypertension

Whether the vasoconstrictive actions of caffeine are enhanced in hypertensive persons has not been demonstrated. Thus, caffeine (3.3 mg/kg) versus placebo was tested in 48 healthy men (aged 20 to 35 years) selected after screening on 2 separate occasions. Borderline hypertensive men (n = 24) were selected with screening systolic blood pressure (BP) of 140 to 160 mm Hg and/or diastolic BP 90 to 99 mm Hg. Low-risk controls (n = 24) reported no parental history of hypertension and had screening BP < 130/85 mm Hg. Participants were then tested on 2 occasions after 12-hour abstinence from caffeine in each of 2 protocols; this required a total of 4 laboratory visits. Caffeine-induced changes in diastolic BP were 2 to 3 times larger in borderline subjects than in controls (+8.4 vs +3.8 mm Hg, p < 0.0001), and were attributable to larger changes in impedance-derived measures of systemic vascular resistance (+135 vs +45 dynes.s.cm-5, p < 0.004). These findings were consistent and reached significance in both protocols. The percentage of borderline subjects in whom diastolic BP changes exceeded the median control response was 96%. Consequently, whereas all participants exhibited normotensive levels during the resting predrug baseline, 33% of borderline subjects achieved hypertensive BP levels after caffeine ingestion. Thus, in borderline hypertensive men, exaggerated responses to caffeine were: selective for diastolic BP, consistent with greater vasoconstriction, replicated in 2 protocols, and representative of nearly all borderline hypertensives. We suspect that the potential for caffeine to stabilize high resistance states in susceptible persons suggests that its use may facilitate their disease progression, as well as hinder accurate diagnosis and treatment.

Caffeine and behavioral stress effects on blood pressure in borderline hypertensive Caucasian men

Caffeine in dietary amounts raises blood pressure (BP), and its use increases during work stress; however, caffeine combined with behavioral stress has not been tested in borderline hypertensive (BH) men. Accordingly, this study tested a psychomotor stressor plus caffeine (3.3 mg/kg, equivalent to 2-3 cups of coffee) using a double-blind, crossover design in 24 BH men (140/90 mmHg < or = BP < or = 160/95 mmHg) and 24 controls (BP < or = 135/85 mmHg). BH men had modestly larger BP increases to the task and showed a greater combined effect of caffeine plus the task (+15/+11 mmHg) than controls (+10/+6 mmHg). BH men maintained response to the stressor in the face of an exaggerated BP response to caffeine, suggesting that use of caffeine during behavioral stress may elevate BP in BH individuals to a clinically meaningful degree.

Caffeine elevates blood pressure response to exercise in mild hypertensive men

The present study examined the effects of caffeine on blood pressure (BP) regulation in hypertensive men during exercise. Twenty unmedicated, mild hypertensives (HT, BP = 140/90 to 160/105 mm Hg) and 12 age-matched, normotensives (NT, BP < 130/80 mm Hg) performed 30 min of extended bicycle exercise following a single dose of caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coffee) and placebo in a double-blind, cross-over design. Hemodynamic measurements were made at predrug, 40-min postdrug and during exercise. At predrug baseline, HT had significantly higher HR (67 v 57 beats/min) and BP (141/96 v 118/72 mm Hg) than NT. At postdrug baseline, caffeine increased systolic and diastolic BP, and peripheral vascular resistance (P < .01 in all cases), decreased HR (P < .05) and did not significantly change stroke volume and cardiac output for both groups. During exercise, HR response was greater on caffeine day than placebo day in HT (P < 0.05) only. Systolic BP was consistently elevated on caffeine day compared to placebo day in both groups (P < .001). Diastolic BP was elevated in HT for 30 min of exercise on caffeine day, but this pressor effect disappeared at 15 min of exercise in NT. As a result, rate-pressure products were significantly higher on caffeine days in HT at postdrug and during exercise. On caffeine day, 7 (39%) HT and 1 (8%) NT showed an excessive BP response (> 230 for systolic or > 120 for diastolic) during exercise. In conclusion, caffeine has significant hemodynamic effects on mild hypertensives at rest and during exercise. The increased rate-pressure products following caffeine during exercise place a greater workload on the heart, and abstinence from caffeine, especially before exercise, may be beneficial for persons with hypertension.

Adrenocortical effects of caffeine at rest and during mental stress in borderline hypertensive men

We examined the effect or dietary doses of caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coffee) on adrenocortical responses to behavioral stress in borderline hypertensive (BH) men using a randomized, double-blind, caffeine-placebo crossover design. Cortisol levels were assessed in BH men and matched normotensive (NT) controls at rest and in response to 35 min of continuous work on a psychomotor task alternating with mental arithmetic. Caffeine at rest elevated cortisol among BHs hut not among NTs. Both groups showed significant cortisol responses to caffeine combined with the tasks. These findings may have implications for the dietary use of caffeine in persons at risk for hypertension when faced with stressful situations.

Effect of aging on atenolol pharmacokinetics and pharmacodynamics

A study was conducted to characterize and compare the pharmacodynamics and pharmacokinetics of atenolol in young and elderly men. Six young (mean +/- SD, 25.0 +/- 3.0 years) and six elderly (63.0 +/- 3.2 years) healthy men took atenolol 100 mg orally once daily for 6 days. Heart rate response to submaximal exercise was measured at selected times for 48 hours, and plasma and urine samples were collected over the same time interval. The Sigmoid Emax model was fit to percent reductions in exercise heart rate and atenolol plasma concentrations. The younger men had significantly lower values for area under the steady-state plasma concentration-time curve and higher values for systemic clearance/F and renal clearance. EC50 values showed a trend toward greater sensitivity to the negative chronotropic effects of atenolol among the elderly men. Model-derived percent reductions in heart rate were greater at all concentrations among the elderly men. These data suggest that group differences in atenolol pharmacokinetics were likely a result of age-related decline in renal function, and that the elderly subjects were at least as sensitive as, and maybe even more sensitive than, the younger subjects to the negative chronotropic effects of atenolol.

Insulin attenuates norepinephrine-induced venoconstriction. An ultrasonographic study

To directly assess insulin-related venomotor changes objectively and quantitatively, we used a modified ultrasonographic technique to measure venous diameter. Ten healthy men and women were studied by use of an Acuson 128 XP ultrasonograph with a linear 7.5-MHz ultrasonographic transducer (sensitivity, +/- 0.1 mm). Venous diameter was measured with the arm kept at 30 degrees elevation and with a pneumatic cuff above the elbow inflated at 40 mm Hg for the last 2 minutes of each 5-minute observation period. Norepinephrine was infused at incremental concentrations of 12.5, 25, 50, and 100 ng/min (75, 150, 300, and 600 pmol/min, respectively) for 5 minutes each. Maximal venoconstriction was achieved by the dose of 100 ng/min norepinephrine, which was then combined with insulin doses of 8, 16, 24, and 32 microU/min (60, 120, 180, and 230 fmol/min, respectively) for 5 minutes each. In six different subjects, methylene blue, an inhibitor of guanylate cyclase, was infused simultaneously with 32 microU/min insulin and 100 ng/min norepinephrine. Mean resting diameter of the vein (1.8 +/- 0.6 mm [mean +/- SD]) increased (to 3.0 +/- 1.0 mm) after cuff inflation. Incremental doses of norepinephrine caused highly reproducible dose-dependent decrease in venous diameter (to 1.8 +/- 0.6 mm, P < .001). Incremental doses of insulin, when combined with the maximum dose of norepinephrine, caused highly reproducible dose-dependent increases in mean venous diameter (P < .001) compared with norepinephrine alone. Methylene blue, which had no independent effect on venous diameter, inhibited the venodilator effect of insulin (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Procalcitonin increase after endotoxin injection in normal subjects

As procalcitonin concentrations have been shown to be elevated in patients with septicemia and gram-negative infections in particular, we proceeded to investigate the effect of endotoxin, a product of gram-negative bacteria, on procalcitonin concentrations in normal human volunteers. Endotoxin from Escherichia coli 0113:H10:k, was injected i.v. at a dose of 4 mg/kg BW into these healthy volunteers. Blood samples were obtained before and 1, 2, 4, 6, 8, and 24 h after injection of the endotoxin. Each patient's cardiovascular and overall clinical status was monitored over this period. The patients developed chills and rigors, myalgia, and fever between 1-3 h. Tumor necrosis factor-alpha levels increased sharply at 1 h and peaked at 90 min, reaching the baseline concentration thereafter by 6 h. Interleukin-6 levels increased more gradually, peaking at 3 h and reaching the baseline concentration at 8 h. The procalcitonin concentration, which was undetectable (< 10 pg/mL) at 0, 1, and 2 h, was detectable at 4 h and peaked at 6 h, maintaining a plateau through 8 and 24 h (4 ng/mL). There was no elevation of calcitonin concentrations, which remained below 10 pg/mL, the lowest sensitivity of the assay. Procalcitonin was measured by a two-antibody immunoradiometric assay specific for this peptide, with no cross-reactivity with calcitonin, katacalcin, or calcitonin gene-related peptide. We conclude that endotoxin induces the release of procalcitonin systemically, that this increase is not associated with an increase in calcitonin, and that the increase in procalcitonin associated with septicemia in patients may be mediated through the effect of endotoxin described here. Whether procalcitonin participates in the mechanisms underlying inflammation remains to be investigated.

Prolonged increase in blood pressure by a single oral dose of caffeine in mildly hypertensive men

Caffeine is known to raise blood pressure (BP). We examined a single oral dose of caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coffee) on BP in 18 hypertensive (HTN) and 12 age-matched, normotensive (NT) men for 3 h. Systolic BPs were significantly higher after caffeine for both groups (P < .001) for the entire 3 h. The HTN group showed persistent elevation in diastolic BP for 3 h, whereas the increment of diastolic BP became smaller in the NT group 90 min after caffeine ingestion. Our results suggest that caffeine consumption may affect both diagnosis and treatment of hypertension and abstinence from caffeine may be beneficial, especially for hypertensive individuals.

Dose- and time-dependent cardiovascular responses induced by ethanol

Four groups of male Sprague-Dawley rats (10/group) were instrumented to permit access to venous and arterial blood and comprehensive cardiovascular measurements for 4 h after intragastric administrations of water or 2, 4 or 6 g/kg of ethanol. Maximum blood concentrations for each increasing dose occurred within 45 min after ethanol attaining peaks of 63 +/- 8, 103 +/- 11 and 221 +/- 33 mg/d, respectively. Cardiac outputs were significantly lower than the control group beginning at 15 min for 4 and 6 g/kg and at 120 mins for 2 g/kg with similar effects on stroke volume for the three doses. Systemic vascular resistance and heart rate were consistently increased throughout the 4 h for the 6 g/kg group. There was a delayed mean arterial blood pressure decrease in the 6 g/kg group beginning at 120 min after ethanol with significant effects in the 4 g/kg group at 60 and 120 min. Decreased central venous pressure and respiration rate prevailed during the 4 h after 6 g/kg. Blood glucose concentrations were elevated at 60 min after 6 g/kg and at 240 min for all doses. However, blood temperatures were consistently lower than the control group after all three doses beginning 45 min after the drug. These data demonstrate that ethanol evokes cardiovascular, respiratory and metabolic changes that are both dose- and time-dependent. Cardiac output and systemic vascular resistance are significantly affected suggesting a marked alteration of peripheral blood flow.

Comparison of Staphylococcus aureus and Escherichia coli infusion in conscious rats

The purpose of this study was to compare the pathophysiology of bacteremia produced by intravenous infusion of either a Gram-positive (Staphylococcus aureus) or a Gram-negative (Escherichia coli) organism. Conscious, unrestrained, instrumented rats received S. aureus, E. coli, or sterile saline over 120 min, followed by a 240-min monitoring period. The infusates produced 90% (S. aureus,) 80% (E. coli), and 0% (saline) mortality at 24 hr. Neither bacterial group produced hypotension during the entire 360-min study period. E. coli produced early tachycardia and increased glucose, followed by decreased stroke volume and increased lactate and pO2. S. aureus caused early tachycardia followed by decreased pH, stroke volume, and cardiac output and increased lactate and systemic vascular resistance. Respiration rate and central venous pressure were not affected by either bacterial infusion. Compared to E. coli, S. aureus produced decreased pH, glucose, pO2, heart rate, and cardiac output and increased lactate, hematocrit, pCO2, and systemic vascular resistance. These data document quantitative differences in the acute response of the conscious rat to bacteremia caused by these isolates of E. coli and S. aureus.

Cardiac adaptation to increased systemic blood pressure in borderline hypertensive men

The present study examined cardiac characteristics of borderline hypertensive men with a positive parental history of hypertension. Hemodynamics in relation to left ventricular function and structure were evaluated in 15 borderline hypertensive men with a parental history of hypertension and in 20 normotensive control subjects with a negative parental history. Groups were matched in age, height, weight and percent body fat. Left ventricular mass and dimensions were measured by M-mode echocardiography, and left ventricular function was assessed by radionuclide ventriculography. Both groups had similar left ventricular mass, dimensions and wall thicknesses. In relation to control subjects, borderline hypertensive men had a significantly higher heart rate and blood pressure (BP) (p < 0.001), but a similar cardiac index. Borderline hypertensive men had a higher peripheral resistance index (p < 0.02), longer time to peak filling rate, and reduced cardiac efficiency, whereas they had higher contractility, minute and stroke work indexes than did control subjects (all p < 0.05); they also had higher diastolic BP (p < 0.03) during exercise, and sustained higher BP during recovery than did controls. Although this group of borderline hypertensive men did not have an altered cardiac anatomy, they had an increased vascular resistance, an altered diastolic function and a reduced cardiac efficiency while undergoing a greater work load. These cardiodynamic profiles are consistent with functional vascular changes and a parallel compensation by the heart.(ABSTRACT TRUNCATED AT 250 WORDS)

Impedance cardiography used to assess patterns of cardiovascular response to behavioral stressors

This paper presents two examples of how impedance cardiography may be used to interpret the hemodynamic influences on blood pressures measured during behavioral stress. In Study 1, blood pressure changes which were similar during two tasks were shown to have important differences in their cardiac output and vascular resistance components. During work on a reaction time task having aversive incentives compared with a neutral task, the blood pressure changes were seen to be associated with lowered vascular resistance and raised cardiac activity, a "fight-flight" pattern. In Study 2, blood pressure response differences between two subject groups working on an identical task were found to have blood pressure changes differing in their underlying cardiac and vascular components as measured by impedance. Such uses impedance cardiography have widespread potential application in psychophysiological research with humans.

Consistency of cardiovascular response pattern to caffeine across multiple studies using impedance and nuclear cardiography

This paper illustrates the use of impedance cardiography in an applied research setting to examine some of the pharmacological effects of caffeine on cardiovascular function. A primary advantage of the technique was in providing a noninvasive approach for studying cardiac versus vascular mechanisms underlying blood pressure responses to acute caffeine challenge. Impedance cardiography allowed the quantification of stroke volumes and cardiac output, and the change in these variables over time in a within-subjects design. Systemic vascular resistances were then calculated when impedance data were combined with simultaneously measured blood pressures. Results from four studies are summarized in which caffeine significantly elevated systolic and diastolic blood pressures. Impedance-derived measures indicate that caffeine's pressor response can be attributed to increased systemic vascular resistance rather than to elevated cardiac output. Our findings were consistent across all four studies, and across all protocols within those studies. Furthermore, these response patterns were confirmed by obtaining similar results using nuclear ventriculography. Thus, with respect to the outcome of testing an applied question, impedance-derived findings were found to be reliable and valid when compared with another technique used more commonly in clinical settings.

Cardiovascular responses to occupational stress in male medical students: A paradigm for ambulatory monitoring studies

Hemodynamic responses to systematic variations in occupational stress were examined using ambulatory blood pressure monitors (ABPMs). The goals of this study were (a) to illustrate the effectiveness of employing naturally occurring, controlled variations in psychological stress levels in studies incorporating ABPMs and (b) to document the patterns of cardiovascular responses to acute examination stress in medical students. Heart rate, systolic blood pressure, diastolic blood pressure, rate-pressure product, and mood states were measured before, during, and after low-stress (lecture) and high-stress (examination) work in 44 healthy male medical students. The lecture day was characterized by stable patterns of cardiovascular activity across all three periods. Hemodynamic activity and reports of activation and distress were greater on the examination day than on the lecture day. Cardiovascular activity during the preexamination period was as high as that seen during the examination period itself, indicating an anticipatory stress effect. Pressor activity decreased after the examination, although some residual chronotropic activity was seen. Systematic changes in physiological responses to controlled variations in the level of this naturalistic stressor support the use of this paradigm for other ABPM studies. The elevations in preexamination responses seen here suggest the need to consider prestressor experiences in such studies.

Hemodynamic characteristics of young men at risk for hypertension at rest and during laboratory stressors

Examined hemodynamic activity--at rest, during mental arithmetic, and during hand cold pressor--in young men varying in risk for hypertension. Classification into low-risk (n = 72), moderate-risk (n = 20), and high-risk (n = 13) groups was based on resting systolic blood pressure (SBP) and parental history of essential hypertension (PH). Dependent variables were SBP, diastolic BP (DBP), heart rate, and rate-pressure product (RPP). Progressively greater hemodynamic activity was seen across risk groups at rest and during the tasks. Risk groups differed significantly in SBP, DBP, and RPP at baseline (ps less than .003) and in size of response to mental arithmetic (ps less than .05) but not to cold pressor. These relationships were either absent or weaker when using either risk factor alone to form risk groups. These findings suggest that hemodynamic reactivity to mental stress is predicted better by a combination of resting SBP and PH than by either risk factor alone and that physiological reactivity may be an important accompaniment of increased risk for hypertension.