An overview of the problem: exercise training and orthostatic intolerance

The questions, whether endurance exercise training (a) induces orthostatic intolerance and (b) alters blood pressure regulation during orthostasis, have been debated since the early 1970s. This symposium presents data that both support and discount the concepts. In addition, data were presented that document invasive and noninvasive techniques of measurement used during investigations of baroreflex and hemodynamic mechanisms of blood pressure regulation during lower body negative pressure (LBNP), a laboratory technique that simulates orthostasis. These techniques and the results obtained enabled the formulation of a hypothetical mechanism of explanation of the "pro and con" of the debated questions.     

Effect of caffeine on the recognition of and responses to hypoglycemia in humans

OBJECTIVE: To determine whether two effects of acute caffeine ingestion--decrease in cerebral blood flow and increase in brain glucose use--alter the recognition of and physiologic responses to hypoglycemia. DESIGN: On two occasions, a hyperinsulinemic glucose clamp technique (2 mU/kg body weight per minute) was used to maintain plasma glucose at 5 mmol/L for 90 minutes, followed by 60 minutes at 3.8 mmol/L, and then 2.8 mmol/L. After 30 minutes at 5 mmol/L, participants consumed, using a randomized, double-blind design, caffeine-free cola with or without caffeine (400 mg) added. SETTING: Yale Clinical Research Center. PARTICIPANTS: Eight healthy, nonobese volunteers (5 men; age range, 20 to 33 years). MEASUREMENTS: Middle cerebral artery velocity (V MCA), counter-regulatory hormone levels, hypoglycemic symptoms, and cognitive function (P300 evoked potentials). RESULTS: Caffeine caused an immediate and sustained 23% decrease in VMCA from 64 to 49 cm/s (point estimate of difference, +15 cm/s [95% CI, 10 to 21 cm/s], P < 0.001). At a glucose level of 3.8 mmol/L, only the participants given caffeine had warning symptoms and "felt hypoglycemic." Moreover, the level of epinephrine was 118% ([CI of point difference, 76% to 158%] [CI, P < 0.001]) higher after caffeine consumption compared with placebo. Similarly, levels of norepinephrine (41% [CI, 26% to 60%], P < 0.002), cortisol (65% [CI, 26% to 78%], P < 0.008), and growth hormone (60% [CI, 16% to 143%], P < 0.05) were higher after caffeine consumption compared with placebo. At 2.8 mmol/L, epinephrine (40% [point estimate of the percentage difference], P < 0.05), norepinephrine (27%, P < 0.05), and cortisol (24%, P < 0.05) levels were higher, participants were more aware (P < 0.02) of hypoglycemia, and P300 latency was prolonged in the group that consumed caffeine (7.2%, P < 0.05). CONCLUSIONS: Acute ingestion of caffeine is associated with sympathoadrenal activation and awareness of hypoglycemia at a glucose level not usually considered hypoglycemic. Our data suggest that individuals who ingest moderate amounts of caffeine may develop hypoglycemic symptoms if plasma glucose levels fall into the "low-normal" range, as might occur in the late postprandial period after ingestion of a large carbohydrate load.     

Uterine tumors resembling ovarian sex-cord tumors. A clinicopathologic analysis of fourteen cases

Uterine tumors with histologic resemblances to ovarian sex-cord tumors were encountered in 14 women in the fourth to sixth decades of life, most of whom had abnormal vaginal bleeding and enlarged uteri suggesting leiomyomas. The tumors in six cases (Group I) were identical to one or another form of well-recognized endometrial stromal tumor except for focal epithelial-like differentiation resembling that seen in sex-cord tumors. These tumors were mostly poorly circumscribed large mural masses. The focal sex-cord-like differentiation was manifested by cords, trabeculae, nests and tubules of epithelial-like cells; eosinophilic bodies resembling Call-Exner bodies were seen in one case. Five of the six patients with tumors of this type have been followed for postoperative intervals of 22 months to 15 years, and pelvic recurrences have developed in three. The tumors in eight cases (Group II) differed from those in Group I by having a predominant or exclusive pattern reminiscent of an ovarian sex-cord tumor. These tumors, most of which were single, well-circumscribed, yellow to tan, mural masses 4 to 10 cm in diameter, appeared benign, with no recurrence during postoperative periods of four months to seven years. The relations of the two groups of tumors to one another and to previously described similar tumors. including so-called granulosa-cell tumors and "plexiform tumors" of the uterus, are discussed, and an origin from endometrial stromal cells is postulated.     

College students'' high-risk sexual behavior following alcohol consumption

A new and portable electronic device called the "Digital Phagometer" is described for the time based counting of spontaneous swallowing. This device is composed of a piezoelectric sensor and a digital event counter/ recorder which can be downloaded to any IBM-compatible PC. The sensor of Digital Phagometer is placed and fixed on the coniotomy region between the cricoid and thyroid cartilage. In this way, it is capable of sensing each upward and downward movement of the larynx produced by spontaneous movement as a function of time. Spontaneous swallowing was measured 1-4 h after lunch in 21 normal subjects and 21 patients with Parkinson's disease (PD). The mean frequency of spontaneous swallowing was 0.8 counts/min in PD patients and 1.18 counts/ min in normal subjects (p < 0.05). During the intake of 200 ml water, the mean frequency of voluntary swallowing did not differ significantly between the two groups (24.6 counts/min in normals vs. 22.3 counts/min in PD patients), but the time necessary to swallow the same volume of water was longer in the PD group.     

The use of EUS to diagnose malignant portal venous system invasion by pancreatic cancer

BACKGROUND: CT scanning and mesenteric angiography are insensitive tests diagnosing vascular invasion by pancreatic cancer. Endoscopic ultrasound (EUS) has been proposed as an alternative. The sensitivity, specificity, and accuracy of specific EUS criteria for diagnosing malignant invasion of the branches of the portal venous system have not been determined. METHODS: This is a prospective blinded evaluation of EUS and angiography to diagnose malignant invasion of the portal venous system by pancreatic cancer in 45 patients, 28 of whom underwent surgery. Surgical staging was used as the gold standard for determining the accuracy of EUS and angiography. RESULTS: Four EUS criteria were studied and the overall accuracy rates were as follows: irregular venous wall (87%), loss of interface (78%), proximity of mass (73%), and size (39%). Although "irregular venous wall" was the most accurate, it suffered from a low sensitivity rate (47%) because of its relative inability to detect superior mesenteric vein invasion (sensitivity of 17%). The angiographic criteria had accuracy rates of 73% to 90% with low sensitivity rates (20% to 77%). The clean resection rate was 86% when all tests were used, 78% if EUS was used without angiography, and 60% if only angiography was used. CONCLUSION: EUS is highly sensitive for detecting portal and splenic vein invasion by pancreatic cancer, but may be insensitive for superior mesenteric vein involvement.