Plasma dopamine-beta-hydroxylase in uremia. Plasma dopamine-beta-hydroxylase (DBH) activity was found to be low in 26 uremic patients when compared with 56 normal individuals (p less than 0.001). Hemodialysis caused only a slight increase in plasma DBH levels in the uremic group. In contrast, a group of kidney transplanted patients with a return of good renal function had DBH values similar to the normal group (p greater than 0.1). The mean plasma DBH activity in eight patients measured pre- and post-transplantation increased from 4.5 to 28 International Units/l (p less than 0.01). No evidence was found to indicate that the depressed levels of plasma DBH in uremia were secondary to genetic or enzyme inhibiting factors. It is suggested that low levels of DBH activity in patients with renal failure may be a consequence of altered sympathetic nervous activity which is known to occur in the uremic state.

Adolescent↗

PubMed1975

[Identification of Group A streptococci from throats of school children in Northern Taiwan].

A total of 2,750 strains of beta-hemolytic streptococci was isolated from 10, 510 throat swabs collected from school children in the Taipei area. Most of them were classified as group A (61%) and group G (34%), and about 5% belonged to other groups or unclassified strains. 1, 772 strains of beta-hemolytic streptococci isolated from healthy school children, and 69 strains from sick school children were grouped by the Lancefield precipitin test, fluorescent antibody technique and/or bacitracin paper disk method. A satisfactory correlation (over 90%) was obtained by the latter 2 methods, when compared with the results of the Lancefield technique. The occurrance of false negative or false positive was only 1 or 5%, respectively.

Bacteriological Techniques↗

PubMed1970

Comparison of the effect of length of exposure to high pressure helium-oxygen on brain gamma-aminobutyric acid levels in male and female mice.

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Aminobutyrates↗

PubMedDate not supplied

Measurement of oscillatory flow pressure gradient in an elastic artery model.

In vitro experiments were conducted to measure the oscillatory flow pressure gradient along an elastic tube in order to assess the recent nonlinear theory of Wang and Tarbell. According to this theory, in an elastic tube with oscillatory flow, the mean (time-averaged) pressure gradient cannot be calculated using Poiseuille's law. The effect of wall motion creates a nonlinear convective acceleration, and an induced mean pressure gradient is required to balance the convective acceleration. The induced mean pressure gradient depends on the diameter variation over a cycle, the pulsatility and unsteadiness of the flow, and the phase difference between the pressure wave form and the flow wave form. The amplitude of the pressure gradient also depends on these parameters and may deviate significantly from Womersley's rigid tube theory. A flow loop was constructed to produce oscillatory flow in an elastic tube. Flow wave forms were measured with an ultrasonic flow probe, and ultrasonic diameter crystals were used to measure wall movement. A special device for pressure drop measurement was constructed using Millar catheter tip transducers to obtain both forward and backward pressure drops that were then averaged. This averaging method eliminated the static error of the pressure transducers. The pressure-flow phase angle was varied by clamping a distal elastic section at various locations. Pressure gradients were obtained for a range of phase angles between -55 degrees and +49 degrees. The mean and amplitude of the measured pressure gradient were compared to theoretical values. Both positive and negative induced mean pressure gradients were measured over the range of phase angles. The measured pressure gradient amplitudes were always lower than predicted by Womersley's rigid tube theory. The experimental means and amplitudes are in good agreement with the elastic tube theoretical values. Thus, the experiments verify the theory of Wang and Tarbell.

Arteries↗

PubMedDate not supplied

Arboviruses as aetiological agents of encephalitis in the People's Republic of China.

A serological study was undertaken to determine the role of arboviruses as etiological agents of encephalitis in the People's Republic of China (PRC). Paired sera were collected during mosquito seasons in 1988-1990 from 614 patients with possible viral encephalitis in 15 regions of PRC and tested for haemagglutination inhibiting antibodies to selected arboviruses. Seroconversions were documented to alphavirus and flavivirus antigens in 13.0 and 18.7% of patients respectively in most of the study areas. No California group seroconversion was detected. The age of alphavirus seroconvertors ranged from 2 months to 32 years and of flavivirus seroconvertors from 6 months to 50 years, with higher numbers in males. Serious central nervous system manifestations were seen more commonly in flavivirus seroconvertors. This study affirms the importance of flavivirus as causative agents of encephalitis in PRC and provides evidence that one or more alphaviruses are causing symptomatic infections with neurological involvement in PRC.

Adolescent↗