Moderate potassium supplementation in essential hypertension

23 unselected patients with mild to moderate essential hypertension, whose average supine blood pressure after two months' observation on no treatment was 154/99 mm Hg, were entered into an eight week double blind randomised crossover study of one month's treatment with slow release potassium tablets (60 mmol/day) versus placebo without alteration of dietary sodium or potassium intake. By the fourth week mean supine blood pressure had fallen by 4% on potassium supplementation compared with placebo. Urinary potassium excretion increased from 62 +/- 4.7 mmol/24 h on placebo to 118 +/- 7.4 mmol/24 h on potassium. The fall in blood pressure was not related to urinary sodium excretion before entry to the trial or while on placebo. Moderate potassium supplementation caused a small but significant fall in blood pressure in patients with mild to moderate essential hypertension and could be additive to the effects of moderate sodium restriction. This increase in potassium intake could be achieved with a potassium-based salt substitute and a moderate increase in vegetable and fruit consumption. Moderate dietary sodium restriction with dietary potassium supplementation may obviate or reduce the need for drug treatment in some patients with mild to moderate hypertension.

Dissociation of mannan--serum complexes and detection of Candida albicans mannan by enzyme immunoassay variations

Candida albicans mannan was added to normal human sera and the resulting complexes were dissociated by boiling (boil) with EDTA or by alkali treatment (bead method). The mannan released was detected by "sandwich" enzyme immunoassay (EIA) or by EIA inhibition. Each EIA took 2.3 h to perform. The total time for the boil-EIA combination was 2.7 h and for the bead-EIA, 3.8 h. The temperature favorable for antigen--antibody incubation was 4 degrees C. The sandwich EIAs were preferable to EIA inhibition because absorbance was directly proportional to mannan concentration, within-run variation was decreased, and accuracy was increased. The boil-sandwich EIA had the highest sensitivity in the 12.5 to 200 micrograms/L range.

Dissociation of mannan--serum complexes and detection of Candida albicans mannan by enzyme immunoassay variations

Candida albicans mannan was added to normal human sera and the resulting complexes were dissociated by boiling (boil) with EDTA or by alkali treatment (bead method). The mannan released was detected by "sandwich" enzyme immunoassay (EIA) or by EIA inhibition. Each EIA took 2.3 h to perform. The total time for the boil-EIA combination was 2.7 h and for the bead-EIA, 3.8 h. The temperature favorable for antigen--antibody incubation was 4 degrees C. The sandwich EIAs were preferable to EIA inhibition because absorbance was directly proportional to mannan concentration, within-run variation was decreased, and accuracy was increased. The boil-sandwich EIA had the highest sensitivity in the 12.5 to 200 micrograms/L range.

Role of presynaptic calcium ions and channels in synaptic facilitation and depression at the squid giant synapse

1. The roles of presynaptic calcium influx and calcium accumulation in synaptic facilitation and depression were explored at the giant synapse in the stellate ganglion of the squid. 2. Calcium currents were recorded in the presynaptic terminal, using a three-electrode voltage clamp and blocking sodium and potassium currents pharmacologically. The calcium influx was constant during pairs or trains of brief depolarizing pulses that elicited facilitating or depressing excitatory post-synaptic potentials (e.p.s.p.s). 3. The relationship between calcium influx and transmitter release during brief depolarizing pulses of varying amplitude resembled a power function with exponent of about 2. 4. Presynaptic calcium concentration transients were measured by injecting the dye arsenazo III and detecting absorbance changes microspectrophotometrically. Increments in intracellular free calcium accompanying single action potentials appeared constant for repeated action potentials that elicited facilitating e.p.s.p.s. 5. The presynaptic calcium concentration remains elevated for several seconds following action potentials. 6. Presynaptic injection of calcium ions by interbarrel ionophoresis evokes a postsynaptic depolarization, apparently reflecting a large increase in miniature e.p.s.p. frequency. Presynaptic action potentials remain unaffected by this treatment, but e.p.s.p.s triggered by them are facilitated for several seconds, and then depressed. 7. The results are consistent with the hypothesis that synaptic facilitation is due to the action of residual calcium or a calcium complex remaining in the presynaptic terminal after electrical activity. The late depression of release during calcium injection may be a result of the continual release of transmitter and consequent depletion of a presynaptic store.

Diagnostic strategy in evaluation of renal abscess

The diagnosis of renal abscess is still a challenging problem. Early manifestations are usually nonspecific and nonlocalizing. Clinical picture, laboratory data, and intravenous pyelogram do not always differentiate between inflammatory lesions and neoplastic processes. Two cases with bilateral, metachronous renal abscesses are presented. The use of 111Indium scan is probably the major recent advance used for unmasking this inflammatory lesion. Sonography, computerized tomography scan, and even arteriography are sometimes necessary to establish reliable preoperative diagnosis. The diagnostic strategy for a systematic approach to the lesion is outlined.

Clonorchiasis in Surinam

A 46-year-old Chinese male was admitted to the Deaconesses' Hospital in Paramaribo with severe bleeding from esophagus varices. After being first on a wrong track the diagnosis clonorchiasis was made. The case history of the patient is described. This was the second case of clonorchiasis in Surinam. It is emphasized that imported diseases must be considered, whenever immigrants show up with symptoms.

Studies on the thermal degradation of the H and M antigens of lyophilized histoplasmin

Lyophilized histoplasmin for the agar gel microimmunodiffusion test has been prepared as a candidate World Health Organization Biological Reference Reagent. It was subjected to elevated temperature for given periods of time and analyzed by the capillary precipitin test and the single radial immunodiffusion test to determine the stability of the H and M antigens. H antigen showed no fall in relative potency when incubated at 48 degrees C for 20 days. M antigen showed a fall in relative potency after storage at 37 degrees C and 48 degrees C, but the extent of the fall was greater in the radial immunodiffusion test than in the capillary precipitin test. Half-lives of the antigens could not be calculated from the Arrhenius equation because the response curves at each temperature followed different kinetics. However, as based on zero time data, M antigen of the lyophilized histoplasma showed a 20% drop in relative potency when stored at -20 degrees C for 2 years. Other analyses suggested that M antigen of liquid histoplasmin stored at 5 degrees C and of lyophilized histoplasma stored at -20 degrees C was degraded at equal rates.

Ecological distribution of Legionella pneumophila

Bacteria were concentrated 500-fold from 20-liter water samples collected from 67 different lakes and rivers in the United States. The data suggest that Legionella pneumophila is part of the natural aquatic environment and that the bacterium is capable of surviving extreme ranges of environmental conditions. The data further demonstrate the effectiveness of the direct fluorescent-antibody technique for detecting L. pneumophila in natural aquatic systems. Smears of the concentrated samples were screened microscopically for serogroups of L. pneumophila by the direct fluorescent-antibody technique. Virtually all of the 793 samples were found to be positive by this method. The 318 samples containing the largest numbers of positive bacteria which were morphologically consistent with L. pneumophila were injected into guinea pigs for attempted isolations. Isolates were obtained from habitats with a wide range of physical, chemical, and biological parameters. Samples collected monthly from a thermally altered lake and injected into guinea pigs demonstrated a seasonality of infection, with the highest frequency of infection occurring during the summer months.

Sensitivity and specificity of enzyme immunoassay for serodiagnosis of influenza A virus infections

Antibodies to influenza virus in sera from 40 patients infected with influenza A/USSR/90/77H1N1-like virus were measured by an enzyme immunoassay (EIA), and results were compared with those obtained by complement-fixation (CF) and hemagglutination-inhibition (HAI) tests. The sensitivity of EIA in detecting an increase in influenza antibody in sera from these 40 patients was intermediate (27 of 40) between the CF test (19 of 40) and the HAI test (35 of 40) when an ether-treater influenza A/USSR/77 virus was used as antigen in all three tests. In contrast with results from HAI tests, however, EIA did not reliably distinguish between infections caused by H1N1 and H3N2 viruses; EIA was thus most comparable in specificity to the CF test. It appears, therefore, that both EIA and CF tests measure antibodies directed to internal antigens common to all type A influenza strains, and that EIA with whole or ether-split influenza virus antigen may be a feasible alternative to the CF test for the type-specific serodiagnosis of influenza infections.

Dynamics of obstruction in acontractile bladder: attempt at management

Five patients with acontractile bladders were observed during lateral voiding cystourethrography in the resting and straining states. Two abnormalities were noted: (1) posterior displacement of the bladder with closure of the posterior vesicourethral angle on straining, and (2) plication of the bladder over the symphysis pubis, resulting in the formation of an anterior pseudodiverticulum. Two other abnormalities are discussed: closure of the anterior vesicourethral angle, and descent of the bladder and prostate in flaccid paraplegia, causing plication at the prostatic apex. Surgical techniques for the correction of the abnormalities are described.

Aequorin response facilitation and intracellular calcium accumulation in molluscan neurones

1. When molluscan neural somata are filled with the calcium-indicating photo-protein aequorin and subjected to a 1 Hz train of depolarizing pulses (0.3 sec duration to + 15 mV) under voltage clamp, the successive photo-emissions due to calcium influx facilitate. The origin of this phenomenon was investigated in identified neurones from the abdominal ganglion of Aplysia californica.2. Since outward currents inactivate cumulatively in successive pulses, the effective depolarization increases due to a series resistance error. Elimination of this error by electronic compensation or pharmacological block of outward current reduced aequorin response facilitation by only about 30%, on the average.3. When voltage-dependent sodium and potassium currents are blocked in tetraethylammonium (TEA)-substituted zero-sodium sea water, the remaining inward calcium currents display no facilitation. On the contrary, a slow decline during a pulse and a slight progressive depression in successive pulses are observed. Barium-substitution for calcium in the same medium eliminates a small residual potassium current insensitive to external TEA. The remaining inward barium currents also display depression instead of facilitation.4. A non-pharmacological separation of calcium current was accomplished by measuring tail currents at the potassium equilibrium potential following depolarizing pulses. Calcium tail currents activate rapidly and then decline gradually and incompletely as depolarizing pulse duration is lengthened. Tail currents also show no evidence of facilitation; there is instead a slight depression of currents after successive pulses.5. Increments of optical absorbance in neurones filled with the calcium-sensitive dye arsenazo III show a depression rather than facilitation to successive depolarizations in a train. The time course of these absorbance signals is consistent with the time-dependent depression of calcium current.6. Calibration of arsenazo III response amplitude indicates that the dye reports only about 1% of the calcium concentration increment expected from knowledge of cell volume and the charge carried by calcium current during a depolarizing pulse. This suggests that cytoplasmic buffering of free calcium must occur rapidly, on a time scale comparable to the response time of arsenazo III (about 1 msec) or more rapidly.7. The slow potassium tail current following a depolarizing pulse is calcium-dependent and probably provides an approximate index of the internal sub-membrane calcium concentration. Increments in this current after repetitive pulses display a slight progressive depression rather than facilitation.8. Since neither calcium currents nor the concentration transients show facilitation, we conclude that aequorin response facilitation is due to the non-linear dependence of aequorin photo-emissions on calcium concentration. This conclusion is supported by a finding that the very different kinetics of arsenazo III responses and aequorin responses can be reconciled by a simple model representing calcium accumulation and known response properties of the two indicator substances.9. In a train of impulses evoked by injecting depolarizing current into a neurone, the successive action potentials grow in duration. Nevertheless, a nearly constant calcium influx signalled by arsenazo III accompanies broadening action potentials.