Comparative characteristics of three cytomegaloviruses from rodents

One cytomegalovirus isolate from the vole (Microtus arvalis) and 2 cutomegalovirus strains from mice (Apodemus sylvatious and Mus musculus) were compared. The rates of inactivation of these 3 viruses were virtually identical after each of 3 treatments: Repeated cycles of freezing and thawing, ultrasonic vibration, and exposure to trypsin and chymotrypsin. The replication of the 3 viruses was similar in each of 3 types of mouse embryo fibroblast cells tested. A number of other characteristics of the vole isolate were the same as those of the mouse strains, including buoyant density (1.20 g/cu cm), enhanced plaquing efficiency in diethylaminoethyl-dextran, and induction of an abortive replication cycle in human cells. The 3 viruses were indistinguishable with regard to their antigenic characteristics, and electron microscopic examination revealed that the nucleocapsids and enveloped virions of the 3 viruses were indistinguishable.

Effect of lithium on catecholamine-induced antidiuresis and cyclic AMP in dog kidneys

Patients treated with lithium salt have an inability to concentrate urine, possible due to the inhibition of the antidiuretic effect of vasopressin. Since beta adrenergic stimulation also induces antidiuresis, a possible effect of lithium on the catecholamine-induced antidiuresis was investigated in dog kidneys. The urinary concentrating ability induced by the iv injection of isoproterenol 0.1 mug/kg was markedly inhibited in the lithium-treated animals (plasma lithium 1.13 plus or minus 0.10 mM). The increase of cyclic AMP concentration by 1 muM isoproterenol was also significantly less in the renal medullary slices obtained from the lithium-treated animals than in those obtained from the control animals. These findings suggest that the inability to concentrate urine in the patients treated with lithium salt is probably due to the inhibition of the antidiuretic effect of catecholamine as well as that of vasopressin; and the inhibitory mechanism of lithium on the catecholamine-induced antidiuresis is possibly through the inhibition of the catecholamine-dependent cycle AMP system in renal medulla.

Catecholamine-dependent cyclic adenosine monophosphate and renin in the dog kidney

Lithium inhibits the catecholamine-dependent cyclic adenosine monophosphate (AMP) generation in the kidney but not the hemodynamic effects of beta-adrenergic stimulation. Therefore, the possible role of catecholamine-dependent cyclic AMP in the release of renin was investigated in lithium-treated dogs both in vivo and vitro. Lithium therapy had no measurable effect on the increase in plasma renin activity induced by an injection of isoproterenol (2.6 plus and minus 1.2 (SE) ng/hour in control dogs vs. 3.0 plus and minus 1.2 ng/hour in lithium-treated dogs, P greater than 0.05). However, lithium inhibited the isoproterenol-induced increase in urinary excretion of cyclic AMP in vivo (791 plus and minus 199 pmoles/min in control dogs vs. 123 plus and minus 129 pmoles/min in lithium-treated dogs, P less than 0.05) and the increase in cyclic AMP concentration in renal tissue in vitro (4.50 plus and minus 0.15 pmoles/ng wet tissue in control dogs vs. 0.34 plus and minus 0.26 pmoles/mg in lithium-treated dogs, P less than 0.01). The finding that, in the lithium-treated dogs, isoproternol increased plasma renin activity but not cyclic AMP generation in the kidney suggests that the increase in plasma renin activity observed after an injection of isoproterenol is probably not mediated through the beta-adrenergic stimulus-dependent cyclic AMP system in the kidney.

Isolation and characterization of acetylcholinesterase and other particulate proteins in the hemolymph of Aplysia californica

Hemolymph of the marine mollusc, Aplysia californica, contains four large particles: acetylcholinesterase, hemocyanin, a hemagglutinin, and a structure tentatively identified as erythrocurorin. We purified the acetylcholinesterase 20-fold by differential centrifugation and filtration through a column of 4% agarose. The freshly isolated esterase complex was found to have a sedimentation coefficient of 69, but the negatively stained enzyme lacked a definite structure in the electron microscope, and appeared as irregular aggregates of a 60 A subunit. The complex was unstable below pH 5 or during storage at 7 degrees. Under these conditions, enzymatic activity remained essentially unchanged. Treatment of the purified enzyme with trichloroacetic acid, organic solvents, and sodium dodecyl sulfate broke the complex down into two major subunits with molecular weights of about 70,000. Exposure of the enzyme to [3H]diisopropylfluorophosphate resulted in the labeling of one of these subunits. Although similar in specificity, the cholinesterase of the blood differed from the enzyme in Aplysia nervous tissue, which is associated with membrane. Treatment with sodium deoxycholate activated the membrane-associated enzyme but inhibited slightly that of the hemolymph; tyrocidine inhibited the hemolymph enzyme but not the enzyme of nervous tissue; and mild digestion with trypsin released the membrane-bound enzyme in an active, soluble form, but inactivated the enzyme of hemolymph. The other particulates of Aplysia hemolymph were partially characterized. Aplysia hemocyanin was similar in structure to other molluscan hemocyanins. When negatively stained, the unit particle appeared to be a disc with a diameter of 280 A and a width of 45 A. These discs were stacked to form long cylindrical arrays. The purified hemocyanin was found to contain 0.26% copper (dry weight). Using differential centrifugation and gel filtration we also obtained a 9-fold purification of Aplysia hemagglutinin. This particle was 120 A in diameter with a dark staining central core of 40 A consisting of 6 subunits. The particle tentatively identified as erythrocurorin appeared as a structure 200 A in diameter consisting of 5 V-shaped subunits.

Inhibition of carbonic anhydrase by parathyroid hormone and cyclic AMP in rat renal cortex in vitro

It has been demonstrated that parathyroid hormone (PTH) inhibits the proximal tubular reabsorption of bicarbonate, and increases the urinary excretion of that ion. There is also a qualitative similarity between the alterations of the proximal tubular reabsorption of phosphate, sodium, and water after PTH administration and after acetazolamide administration. These findings suggest that the renal effect of PTH is possibly mediated through the inhibition of carbonic anhydrase in proximal tubules. Therefore, a possible inhibitory effect of PTH on carbonic anhydrase was evaluated in the homogenate of rat renal cortex by an indicator titration method. Incubation of cortical homogenates with PTH for 10 min at 37degreesC inhibited carbonic anhydrase activity. The inhibitory effect of PTH was ATP-, Mg++-, and K+-dependent and temperature-dependent; inactivation of PTH by heating at 100degreesC abolished the effect of PTH both to activate adenylate cyclase and to inhibit carbonic anhydrase. Calcium 5 mM also partially abolished effects of PTH to activate adenylate cyclase and to inhibit carbonic anhydrase. The inhibitory effect of PTH on carbonic anhydrase was specific to renal cortex. Cyclic AMP, the intracellular messenger substance for PTH, also inhibited carbonic anhydrase in renal cortex. The cyclic AMP-induced inhibition was also Mg++ dependent and temperature dependent, and required preincubation at 37degreesC. But 5'-AMP, a metabolic derivative of cyclic AMP without its biological effect, had no inhibitory effect on carbonic anhydrase. All the above results are consistent with the hypothesis that PTH inhibits proximal tubular reabsorption of bicarbonate and phosphate through the inhibition of carbonic anhydrase, and that inhibitory effect is mediated through the cyclic AMP system.

Comparative studies of the Smith and Raynaud strains of murine cytomegalovirus

A number of the biological, biophysical, and immunological parameters of the Smith and Raynaud strains of murine cytomegalovirus were compared. The two strains were found to be indistinguishable.

Chemical characterization of organisms isolated from leprosy patients

CHEMICAL ANALYSES OF THE CELL WALLS OF ORGANISMS ISOLATED IN VARIOUS PARTS OF THE WORLD FROM CASES OF LEPROMATOUS AND TUBERCULOID LEPROSY MAKE POSSIBLE THEIR ASSIGNMENT TO ONE OF THE THREE GENERA: Corynebacterium, Mycobacterium, or Propionibacterium. One, bacterium 22M, remains unassigned. The combined chemical and enzymatic properties attributed to leprosy bacilli freshly harvested from lepromata are found collectively, but not individually, in these three genera.

Influence of complement on the neutralization of murine cytomegalovirus by rabbit antibody

Antiserum against murine cytomegalovirus produced in the rabbit contained complement (C')-requiring neutralizing (CRN) antibody. The proportion of CRN was extremely high (up to 98%) during the early portion of an immunization procedure, whereas the antisera produced late had a much lower proportion that required C'. The antiserum produced was specific for MCMV with or without C'.

Abortive infection of human diploid cells by murine cytomegalovirus

Inoculation of human diploid cells (WI-38) with murine cytomegalovirus (MCMV) did not result in the synthesis of any infectious virions. However, morphological changes typical of the cytopathic effects (CPE) of MCMV were detectable within 12 hr of infection. The CPE included rounding, swelling, and detachment of cells. The nuclei of infected cells were enlarged, and intranuclear inclusions were visible by May Grunwald-Giemsa staining and by the indirect fluorescent-antibody test. All cells infected at a multiplicity of infection of 3 showed CPE, and these cells could not be passaged successfully. Cell lysates and exhausted media from infected WI-38 cultures did not produce any CPE in WI-38 cells. The virus absorbed to WI-38 cells with the same efficiency as to mouse embryo fibroblast cells (MEF). Samples of MCMV in which virus infectivity for MEF cells had been inactivated by ultraviolet irradiation or by exposure to 56 C failed to produce any of the above signs. MCMV-specific CPE did not occur in the presence of actinomycin D (1 mug/ml) or puromycin (20 mug/ml), but 5'-fluoro-2'-deoxyuridine at 1 x 10(-4)m did not prevent CPE or the development of intranuclear inclusions.