Esophageal tone in patients with total aperistalsis: gastroesophageal reflux disease versus achalasia.
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We have evaluated esophageal tone in two different conditions that, in some cases, similarly impair phasic esophageal motility. Studies were performed in 14 healthy volunteers, 10 patients with total esophageal aperistalsis secondary to gastroesophageal reflux disease (GERD), and 25 untreated achalasia patients. We quantified esophageal compliance and relaxation induced by a nitric oxide donor using a barostat. Intraesophageal volume at a minimal distending pressure (2 mmHg) was not significantly different among all three groups (4.1 +/- 0.7, 3.8 +/- 0.7, and 4.2 +/- 1.2 ml for healthy, GERD, and achalasia groups, respectively). Esophageal compliance was significantly increased (P < 0.05 vs. healthy group) in the two groups of patients with aperistalsis (1.9 +/- 0.2, 3.0 +/- 0.2, and 3.1 +/- 0.3 ml/mmHg for healthy, GERD, and achalasia groups, respectively). Esophageal relaxation was decreased in GERD patients (Delta diameter: 0.4 +/- 0.1 cm) and increased in achalasia patients (Delta diameter: 1.3 +/- 0.4 cm) relative to healthy subjects (Delta diameter: 0.9 +/- 0.2 cm) (P < 0.05 for GERD vs. achalasia and healthy groups). Our results indicate that diseases that similarly impair phasic esophageal motility may affect esophageal tone differently. (+info)
Defective innervation of heart in diabetic autonomic neuropathy.
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Heart rate responses to autonomic stimulation and inhibition were studied in 13 diabetic autonomic neuropathy. Parasympathetic function was impaired in all patients and sympathetic function in most. One patient's heart appeared to be totally denervated. The consequences of cardiac denervation include tachycardia, a fixed heart rate, and a possible tendency to cardiac dysrhythmias, which caused spontaneous cardiac arrests in three patients. (+info)
Adrenergic regulation of blood pressure in chronic renal failure.
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Previous investigations have suggested that significant hypotension during hemodialysis may result from abnormalities of sympathetic nervous system activity. To further evaluate these phenomena, plasma dopamine beta-hydroxylase (D beta H) and cold pressor test (proposed indexes of efferent sympathetic nervous system activity) and amyl nitrite inhalation (an index of the entire baroreceptor reflex arc) were studied in two groups of patients: group I, patients exhibiting a mean arterial pressure decrease to less than 70 mm Hg during less than 10% of dialyses; group II (hemodialysis hypotension), patients with a mean arterial pressure decrease to less than 70 mm Hg during more than 90% of dialyses. The groups were similar with respect to plasma renin activity, renin response to ultrafiltration, age, duration of dialysis, nerve conduction velocity, plasma protein concentration, hematocrit, dialysis weight change, resting heart rate, sex, race, blood pressure and heart rate response to cold pressor test, and 125I-albumin plasma volume. Supine mean arterial pressure was higher in patients with hemodialysis hypotension than in patients without hemodialysis hypotension (group I) both before and after dialysis. Plasma D beta H activity was significantly higher in patients with hemodialysis hypotension (group II) than in group I both before and after dialysis. Amyl nitrite inhalation, expressed as change in delta R-R interval/mean arterial pressure decrease, was less in hemodialysis hypotension patients. These results suggest that hemodialysis hypotension may result from a lesion in the baroreceptors, cardiopulmonary receptors, or visceral afferent nerves. Furthermore, elevated mean arterial pressure in patients with hemodialysis hypotension may be neurogenic in origin, as reflected by plasma D beta H activity, and appears similar to the hypertension that follows baroreceptor deafferentation of experimental animals. (+info)
MUSCULAR SUBAORTIC STENOSIS: THE EFFECT OF PERIPHERAL VASODILATATION.
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Amyl nitrite was administered on two occasions to a patient with muscular subaortic stenosis, to ascertain if selective peripheral vasodilatation would affect the degree of obstruction to left ventricular outflow in this condition. On each occasion there was a marked increase in the systolic pressure gradient across the left ventricular outflow tract prior to the onset of reflex tachycardia. Following the second amyl nitrite inhalation, the systolic cross-sectional area of the left ventricular outflow tract decreased to 1.0 sq. cm., from the control value of 2.6 sq. cm. It is believed that the increased degree of muscular subaortic stenosis, following peripheral vasodilatation, could be secondary to a decrease in the systolic size of the whole left ventricle, or to a selective decrease in the physical size of the left ventricular outflow tract. (+info)
Longitudinal patterns of methamphetamine, popper (amyl nitrite), and cocaine use and high-risk sexual behavior among a cohort of san francisco men who have sex with men.
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Most prior studies examining drug use among men who have sex with men (MSM) have been cross-sectional or retrospective and have not determined whether periods of increased drug use are associated with high-risk sexual behavior at the individual level. In this article, we describe patterns of use of methamphetamines, poppers, and sniffed cocaine and sexual risk behavior among 736 San Francisco MSM enrolled in the EXPLORE study and followed for up to 48 months. In longitudinal analysis, use of methamphetamines, poppers, and sniffed cocaine declined during follow-up. However, compared with older participants, younger participants were more likely to increase their drug use over time. Results of conditional logistic regression demonstrated that high-risk sexual behavior was more common during reporting periods characterized by increased methamphetamine, poppers, or sniffed cocaine use. This within-person analysis found that compared with periods of no drug use, periods of both light drug use (less than weekly use of drugs) and heavier drug use (at least weekly use of at least one drug) were significantly associated with increased risk of engaging in unprotected anal sex with an HIV-positive or unknown-status partner. These results suggest that even intermittent, recreational use of these drugs may lead to high-risk sexual behavior, and that, to reduce and prevent risks of HIV, no level of use of these drugs should be considered "safe." HIV prevention interventions should target MSM who report either light or heavy use of methamphetamines, poppers, and sniffed cocaine. (+info)
Comparative effects of glyceryl trinitrate and amyl nitrite on pulse wave reflection and augmentation index.
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AIMS: The influence of vasodilators on augmentation index (AIx) offers a simple, rapid and noninvasive method of evaluating vascular function. Glyceryl trinitrate (GTN) is widely used as an endothelium-independent vasodilator, although other nitrates that are shorter acting may have advantages in clinical studies. The aim of this study was to compare the effects of two short-acting nitrates, GTN and amyl nitrite, which have differing pharmacodynamic profiles. METHODS: Twenty-one healthy volunteers (15 male; mean age 35 years, range 21-56 years) attended on three occasions and received sublingual GTN (0.5 mg for 3 min), inhaled amyl nitrite (0.2 ml inhaled for 30 s), or no treatment in a randomized cross-over design. Haemodynamic responses of AIx, blood pressure and thoracic bioimpedance (heart rate, cardiac index) were assessed by measurement at baseline, every 60 s for the first 5 min, and then every 5 min for a further 55 min. RESULTS: AIx was reduced by amyl nitrite (peak effect -9 +/- 2% at 1 min, P < 0.002) and GTN (peak effect -12 +/- 3% at 4 min, P < 0.05). Compared with amyl nitrite, the onset and offset of action of GTN was slower. Amyl nitrite initially increased heart rate by 27 +/- 4% (P < 0.001) and cardiac index by 13 +/- 3% (P < 0.001) whereas GTN had no significant effect (P > 0.05). Neither agent affected blood pressure. CONCLUSIONS: GTN causes a slower and more sustained reduction in AIx than amyl nitrite. Although amyl nitrite causes a more rapid fall and recovery in AIx, it induces a reflex tachycardia that may limit interpretation of the initial (1 min) but not later (2 min) changes in AIx. The prolonged offset of GTN suggests that a sufficient washout period must be included when making repeated measures or when assessing the subsequent effects of other agents. (+info)
Methaemoglobinaemia after ingestion of amyl nitrite.
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We report a case of methaemoglobinaemia in a 2 year old girl after ingestion of an 'aphrodisiac' containing nitrite. The availability of these products, their poor labelling, and their intended presence in domestic bedrooms all serve to increase the hazard they pose to young children. (+info)
Substance use and sexual behaviours of Japanese men who have sex with men: a nationwide internet survey conducted in Japan.
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BACKGROUND: Japanese men who have sex with men (MSM), especially those living in large metropolitan areas such as Tokyo and Osaka, are facing a growing HIV/AIDS epidemic. Although the Internet is used as a new venue for meeting sex partners, it can also serve as a useful research tool for investigating the risk behaviours of Japanese MSM. This Internet survey explored the extent of substance use and its association with sexual risk behaviours among Japanese MSM. METHODS: Between 28 February 2003 and 16 May 2003 MSM were recruited through 57 Japanese gay-oriented Web sites, gay magazines, and Internet mailing lists. Participants completed a structured questionnaire anonymously through the Internet. RESULTS: In total, 2,062 Japanese MSM completed the questionnaire. The average age of participants was 29.0 years and 70.5% identified as gay, 20.8% as bisexual, and 8.7% as other. Overall, 34.5% reported never using a substance, 45% reported ever using one type of substance (lifetime reported single substance users), and 19.6% had used more than 1 type of substance (lifetime reported multiple substance users) in their lifetimes. The substances most commonly used were amyl nitrite (63.2%), 5-methoxy-N, N-diisopropyltryptamine (5MEO-DIPT) (9.3%), and marijuana (5.7%). In the multivariate analysis, unprotected anal intercourse, having had 6 or more sexual partners, visiting a sex club/gay venue in the previous 6 months, a lower education level, and being 30 to 39 years of age were associated with both lifetime single and lifetime multiple substance use. Lifetime reported multiple substance use was also correlated with having a casual sex partner, having symptoms of depression, being diagnosed as HIV-positive, and greater HIV/AIDS-related knowledge. CONCLUSION: This is the first Internet-based research focused on the sexual and substance use behaviours of MSM in Asia. Our findings suggest a compelling need for prevention interventions to reduce HIV risk-related substance use behaviours among Japanese MSM. The results also suggest that the Internet is potentially a useful tool for collecting behavioural data and promoting prevention interventions among this population. (+info)