Lipid metabolism in experimental virus infections]

The effect of herpes simplex virus (HSV) and influenza virus (IV) on lipid metabolism was studied. In conditions of acute herpetic infection of rabbits we detected typical dyslipidemia, characterized by increased contents of total cholesterol, beta-cholesterol and triglycerides in the absence of trustworthy differences in concentrations of alpha-cholesterol. The use of antiherpetic preparation furavir, on the background of infection, corrected lipid spectrum of the infected animals. Blood lipid disturbances in acute influenza virus infection of mice were not detected. HSV infection of cell culture of human aorta was accompanied by increased accumulation of free lipids in cells. IV infection, in the same conditions of experiment, did not change the contents of intracellular lipids. The obtained data deepen the existing notions of herpetic and influenza infections pathogenesis and may be useful in understanding etiopathogenesis of certain somatic metabolism diseases.     

In vivo crystal formation in Escherichia coli of an over-expressed soluble form of penicillin-binding protein 5

Accumulation of either native membrane-bound or soluble variants of PBP5 over-expressed in the cytoplasm was investigated by electron microscopy of ultra-thin sections. One of the soluble forms of PBP5 (PBP5s353) formed well-ordered crystals inside the cells. Cells sectioned perpendicular to their long axis showed a diamond-shaped crystal whereas cells cut parallel to their long axis contained a long, narrow crystal. In both sectioning directions an ordered ultrastructure was visible as shown by optical diffraction. Computer processing was used to enhance the crystal images. From this the unit cell parameters were calculated as a = 7.6 nm, b = 4 nm, c = 4.2 nm, gamma = 75 degrees. The calculated unit-cell volume of 120 nm3 is large enough to contain one protein molecule.     

Perturbation of intestinal microvillar enzyme biosynthesis by amino acid analogs. Evidence that dimerization is required for the transport of aminopeptidase N out of the endoplasmic reticulum

The amino acid analogs canavanine, 3-hydroxynorvaline, thialysine, 6-fluorotryptophan, m-fluorotyrosine, and 2-fluorophenylalanine were incorporated into proteins, synthesized in pig intestinal mucosal explants, and their effect on molecular processing and intracellular transport of microvillar enzymes studied. Unless they were used in combination, none of the analogs drastically reduced the expression of aminopeptidase N (EC 3.4.11.2) or sucrase-isomaltase (EC 3.2.1.48, EC 3.2.1.10), but to a varying extent, they all slowed the rate of transport to the apical surface. In contrast, the cellular export of a secretory protein, apolipoprotein A-1, was largely unaffected. For the microvillar enzymes, all six analogs caused an accumulation of the transient, high mannose-glycosylated form, indicating an analog-sensitive stage prior to the Golgi-associated processing. For aminopeptidase N, this arrest was shown to correlate with a reduced ability of its transient high mannose-glycosylated form to form homodimers as judged from cross-linking experiments, suggesting dimerization to be obligatory for transport out of the endoplasmic reticulum.     

Does transpiration have an essential function in long-distance ion transport in plants?

Abstract. Long-term effects of transpiration on growth and on long-distance ion transport were investigated in maize over a whole growth cycle. Maize plants were grown with nutrients supplied at adequate levels in hydroculture or in soil at 50–60% and at >95% relative humidity. Although the amount of water lost by the plants under these conditions differed by a factor 2 to 3, there was neither a decrease in growth (fresh weight and dry weight) nor in ash content of the 'humid'plants. This was also found when the upper part of the shoot (70–150 cm) was tested separately. It is suggested that transpiration is not essential for long-distance transport of mineral elements in plants. Alternatives are discussed.     

Occupational illness and poison control centers. Referral patterns and service needs.

In a study of occupational illness reported to a regional poison control center and to gauge the center''s outreach and services, we did follow-up interviews of 301 case contacts over a 6-month period. We ascertained referral routes, reasons for contacting the poison control center, and awareness of the center''s function. For 122 cases a nonphysician was the initial poison control center contact. Of the nonphysician contacts, 41 had already consulted a health care provider and been referred to the poison control center for assistance. Of the 70 persons with exposure, only 21 had been aware before their exposures that poison control center services might include occupational chemical illness consultation. Physicians and nonphysicians expressed similar reasons for contacting the poison control center, with 118 of 301 identifying the need for an exposure hazard risk assessment. These data suggest that although those contacting a poison control center because of occupational illness include a variety of cases, they have many similar service needs.     

Hormonal control of cardiac lipolysis by glyco(geno)lysis

The importance of the glucose/fatty acid cycle in the control of cardiac lipolysis is emphasized by the following observations. Addition of the glycogen debranching inhibitor deoxynojirimycin or an O2-vehicle, fluorocarbon F-43, to media perfusing paced, lipid-enriched, Langendorff hearts lower cardiac lactate and glycerol 3-phosphate levels together with inhibition of glucagon-stimulated glycerol (and lactate) release. The absence of fluorocarbon during perfusion of 5 Hz paced langendorff hearts probably results in limited tissue oxygenation, resulting in glycogenolysis and lipolysis. The results indicate hormonal control of cardiac lipolysis by glyco(geno)lysis.     

Insect pupil mechanisms

Summary The spectral characteristics of the pupil mechanism in blowfly photoreceptors and their dependence on light intensity have been investigated together with the intensity dependence of the receptor potential. The threshold for the pupil response as measured by reflectance is found at an intensity at which the peak of the receptor potential is about half maximal and the plateau potential starts to saturate. The reflectance saturates at about 3 log-units above threshold. The reflectance spectrum peaks near 620 nm, and its shape is independent of adaptation intensity. The absorbance change, measured by transmission, is extreme in the blue, at about 470 nm. The shape of the absorbance spectrum is slightly intensity dependent, presumably due to optical waveguide effects. The dynamic ranges of the light-induced reflectance and absorbance changes do not coincide. The reflectance change shows saturation at least 1 to 1.5 log units before the absorbance change saturates.