Assessment of caffeine exposure: caffeine content of beverages, caffeine intake, and plasma concentrations of methylxanthines

The caffeine content of all tea or coffee beverages consumed by 17 healthy adults over 24 hours was measured. Plasma caffeine, theophylline, theobromine, and paraxanthine concentrations were determined over the same 24 hours. The average caffeine content per drink was 60.4 +/- 21.8 mg for instant coffee (14-fold range), 80.1 +/- 19.2 mg for brewed coffee (2.8-fold range), and 28.8 +/- 13.7 mg for tea (5.5-fold range). The number of drinks of coffee and tea consumed was a poor index of actual caffeine intake (r2 = 0.42). Caffeine intake correlated poorly with the 24-hour average caffeine concentration (r2 = 0.41), but there was a very good correlation between a single plasma caffeine concentration measured at 5 PM and the 24-hour average concentration (r2 = 0.94). The same was true for paraxanthine (r2 = 0.86). Paraxanthine accounted for 67.3% of the total dimethylxanthines in plasma, while theobromine and theophylline accounted for 24.4% and 8.3%, respectively. Mean caffeine clearance was 1.2 +/- 0.3 ml/min/kg. Plasma caffeine concentration before the first drink in the morning correlated very poorly with caffeine clearance (r2 = 0.07), even when adjusted for caffeine intake (r2 = 0.21).     

Antibodies to HTLV-1 in saliva of seropositive individuals from Japan

Secretory antibodies protect mucosal surfaces against transmission of many viruses. Human T-lymphotropic Virus, Type I (HTLV-I) is transmitted via blood products and via sexual contact across mucosal surfaces. We investigated the presence of HTLV-I-specific antibodies in whole saliva samples from 10 seronegative and 28 seropositive volunteers from a hospital in southern Japan. Antibodies directed to HTLV-I antigens were found in the salivas from 22 of 28 (79%) of the seropositive subjects. None of the seronegative individuals showed evidence of salivary antibodies. Antibodies directed to the envelope antigens of the virus were found in 21 of 22 positive saliva samples. Secretory antibodies may be important in preventing mucosal transmission.     

Prevalence of ECG changes in an unorganized population of Novosibirsk

The paper is concerned with the data on the prevalence of various ECG changes in an open male and female population (aged 25 to 64) in Novosibirsk obtained on examination of a random representative sample. The analysis permitted defining groups of persons with prognostically unfavorable ECG changes serving as a basis for further study of regularities of their appearance.     

The effectiveness of intrauterine transfusions

The results of treatment with intrauterine transfusion are presented. The analysis comprised 48 successful transfusions into 29 foetuses. The reference group consisted of 11 transfusions which proved nonfeasible or ineffective and 54 untreated cases. Following blood treatment, the newborn mortality rate dropped more than threefold. Long-term follow-up of 21 children generally showed their good physical and mental development. We also present 4 cases of supsequent pregnancies after intrauterine blood treatment in a preceding pregnancy, showing that it is possible to save the next baby of the same mother.     

Left ventricular volume, mass, and function following surgical correction of chronic aortic regurgitation

Following surgical correction of chronic aortic regurgitation, left ventricular (LV) volume falls to normal or near normal in most patients; this change generally occurs within the first week after surgery. During the ensuing six months, a significant regression of LV hypertrophy occurs, but most patients do not achieve a normal LV mass. The systolic ejection fraction may increase while the LV end-diastolic pressure almost uniformly falls to normal. Postoperative studies of LV volume mass and function should be aimed at identifying those patients which do not undergo these favorable changes so that medical therapy can be directed at this high risk group.     

Effects of chemicals on delayed matching behavior in pigeons I: acute effects of drugs

Pigeons were trained to peck a red or green center key 15 times to turn it off. After a delay, two side keys, one red and one green were illuminated. Pecks on the side key whose color matched the color that the center key had been produced food. Pecks on the other side key produced a timeout. The effects of various drugs were studied as the delay between extinguishing of the center key light and illumination of side keys was varied from 1 to 8 sec. Pentobarbital and phencyclidine consistently decreased matching, but morphine, d-amphetamine and delta 9-tetrahydrocannabinol had little effect on matching even at doses that increased latency to respond and decreased the rate of responding. Pentobarbital frequently decreased matching at doses below those that increased response latency and decreased response rate, but phencyclidine decreased matching only at doses that increased latencies and decreased rates. The effects of pentobarbital on matching did not depend on the delay duration.