Changes in plasma fibronectin levels in thyroid diseases

The plasma levels of fibronectin (Fn) have been measured in normal subjects and in patients with thyroid diseases. The mean plasma Fn levels in 62 normal adults was 32.0 +/- 6.0 mg/dl, whereas it was elevated to 62.6 +/- 16.1 mg/dl (mean +/- SD) in 25 patients with hyperthyroidism and decreased to 19.2 +/- 8.0 mg/dl in 9 patients with hypothyroidism. The 9 patients with simple goiter have normal values of 29.1 +/- 8.0 mg/dl. With the administration of anti-thyroid drugs, plasma Fn levels normalized, with a time lag, in parallel with normalization of the thyroid function. Positive correlation was obtained between Fn levels and serum levels of triiodothyronine (T3) and thyroxine (T4). The present findings indicate that measurement of plasma Fn both in the basal state and during treatment provides evidence of altered Fn metabolism in thyroid diseases and serves to follow up the effect of treatment.     

Fever in rats during normal and dehydrated conditions

The effect of endogenous pyrogen (EP, from rabbit) and endotoxin (Salmonella typhosa) on rectal temperature (Tre) was investigated in normal and dehydrated rats of both sexes. Intraperitoneal injection of either EP or endotoxin did not affect body temperature. In addition, no changes in Tre were observed when endotoxin was injected intravenously in normally hydrated male rats, but significant falls in Tre occurred in normal female rats. However, intravenous injection of EP produced fever in both sexes, but females generally showed smaller responses. A second intravenous injection of endotoxin, given 3 days after the first injection, always produced fever in normally hydrated rats. The pattern of this febrile response was monophasic. In contrast to the response in normal rats, intravenous endotoxin produced significant fevers with a biphasic pattern in dehydrated rats of either sex, but the febrile responses of male rats were greater than those of female rats. On the other hand, there were no significant differences between febrile responses to intravenous EP exhibited by normal and dehydrated animals. These results show that rats of both sexes possess physiological mechanisms capable of producing a fever following intravenous injections of EP.     

Purification and characterization of an antibacterial factor from snail mucus

The antibacterial factor from the body surface of the African giant snail, Achatina fulica Férussac, was isolated by DEAE-Toyopearl 650M ion exchange chromatography. The isolated preparation exhibited highly positive antibacterial activity both for the Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus and for the Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, but it lost such activity when heated at 75 degrees C for 5 min. The antibacterial factor of the snail mucus was a glycoprotein whose molecular weight (MW) was about 160,000. It was composed of two subunits of MW 70,000-80,000.     

Food preference,food quality and diets of three herbivorous gastropods (Trochidae: Tegula) in a temperate kelp forest habitat

Summary The relationship between food preference and food quality (i.e. a food's contribution to growth and reproductive development) was examined in the laboratory for 3 species of herbivorous kelp forest gastropods (Tegula). The preference hierarchies of the 3 Tegula for 6 common algal species are the same: giant kelp (Macrocystis) is the most preferred food and brown algae are consumed at higher rates than red algae. Despite their strong preference for Macrocystis, the 3 species had significantly greater growth and/or reproductive development on a mixed-algae diet than on either brown or red algae alone. Laboratory preferences of the snails did not correspond closely with caloric content, estimated availability or quality of the algal species used in this study. However, the 3 Tegula are subject to strong benthic predation and Macrocystis provides an important spatial refuge in nature. The potential role of non-nutritional factors such as predator avoidance on the formation of food preferences is discussed.     

Expression of viral early functions in rat 3Y1 cells infected with human papovavirus BK.

A plaque morphology mutant (pm-522) of BK virus (BKV) with a small deletion at map unit 0.72 can readily transform rat 3Y1 cells, but wild-type BKV (wt-501) cannot. We examined the expression of the viral early functions in BKV (wt-501 or pm-522)-infected 3Y1 cells within a 2-week period after infection, before foci of transformed cells became detectable, to know how the difference between the two BKVs occurs. After a high-multiplicity infection, comparable amounts of free viral DNA (forms I and II) were found by Southern blotting analyses to persist in the nuclei of the cells infected with wt and pm BKVs. Whereas the proportion of T antigen-positive cells, as revealed by the indirect immunofluorescence method with complement, remained at a level of 60% in pm BKV infection, the level of T antigen-positive cells in wt BKV infection decreased from the initial 45% to 1% on day 9. The results obtained by the immunoprecipitation analyses of radiolabeled proteins from the infected cells were consistent with the immunofluorescence data. Viral early mRNA was detectable on day 2 and increased on day 9 in pm BKV infection, but in wt BKV infection, the low level of early mRNA detected on day 2 disappeared on day 9. Cell DNA synthesis and cell growth were enhanced more in pm BKV infection than in wt BKV infection. The low level of viral DNA synthesis that occurred in the infected rat cells was more prominent in pm BKV infection than in wt BKV infection. These data indicate that the expression of viral early functions continued much longer in pm BKV-infected rat cells than in wt BKV-infected rat cells, where the expression was probably repressed soon after infection. Continued T antigen production directed by the unintegrated viral genomes appears to be required for efficient transformation of rat cells by BKV.     

Genetic basis of the neurovirulence of pseudorabies virus.

Lomniczi et al. (J. Virol. 49:970-979, 1984) have shown previously that two attenuated vaccine strains of pseudorabies virus have a similar deletion in the short unique (US) region of the genome. The region which is deleted normally codes for several translationally competent mRNAs. As expected, these mRNAs are not formed in the cells infected with the vaccine strains. The function specified by these mRNAs is thus not necessary for growth in cell culture. Using intracerebral inoculation of 1-day-old chicks as a test system, we have attempted to determine whether a gene within the region that is missing from the attenuated strains specifies functions that are required for the expression of virulence. An analysis of recombinants between the Bartha vaccine strain and a virulent pseudorabies virus strain (having or lacking a thymidine kinase gene [TK+ or TK-]) revealed the following. None of the recombinant plaque isolates that were either TK- or which had a deletion in the US was virulent. Not all recombinant plaque isolates which were both TK+ and had an intact US were virulent. These results indicate that both thymidine kinase activity and an intact US were necessary but not sufficient for the expression of virulence. Marker rescue experiments involving cotransfection of the Bartha strain DNA and a restriction fragment spanning the region of the genome that was missing from the Bartha strain resulted in the isolation of virions to which an intact US had been restored. These virions were not virulent but had an improved ability to replicate in the brains of chicks compared with that of the parental nonrescued Bartha strain. Our results show that genes in the US region, which are missing from the Bartha strain, were necessary for virulence but that this strain was also defective in other genes required for the expression of virulence. Thus, the virulence of pseudorabies virus, as measured by intracerebral inoculation into chicks, appears to be controlled multigenically.     

Investigation of actin in Tetrahymena cells. A comparison with skeletal muscle actin by a devised two-dimensional gel electrophoresis method

Total protein constituents of Tetrahymena thermophila strain B1868 III were studied by two-dimensional agarose-polyacrylamide gel electrophoresis to detect actin among the constituents. In the attempts to prepare a whole-cell extract of Tetrahymena, it was found that protease activity in the extract was so high that high molecular components were quickly digested with the endogenous protease into small peptides unless the homogenization and heat-treatment in a sodium dodecylsulfate solution were performed within 5 s. It was eventually found that employment of 8 M guanidine hydrochloride (HCl) in the homogenization of cells perfectly prevented the degradation of protein components, even through a long preparation procedure. A devised two-dimensional agarose-polyacrylamide gel electrophoresis of the guanidine HCl extract gave a 'protein map' on which most proteins were located in their respective positions, including proteins with more than 200,000 mol. wt. Addition of rabbit skeletal muscle actin on the protein map revealed that no protein with isoelectric point and molecular weight identical with those of the actin was contained in the whole Tetrahymena extract, suggesting that Tetrahymena actin may have characteristics far different from those of skeletal muscle actin.     

Statistical measurement of signal transmission in the central nervous system of the crayfish

Summary Transmission of nerve signals in the crayfish brain was studied by means of the transfer function derived from input-output analysis with random stimulation. The transfer function was measured in the form of frequency-response-function and represented by Bode plot. Two classes of the frequency-response-functions were discriminated, corresponding to two types of response patterns evoked by the constant frequency stimuli. The first type had the characteristics of a band pass filter similar to an underdamped resonant circuit. The second one had the characteristics of a phase lag circuit, occasionally, with additional small positive or negative peak at almost the same frequency as the resonance of the first type. A few possibilities for the resonance and the phase lag mechanisms were discussed.     

Pacemaker Potentials for the Periodic Burst Discharge in the Heart Ganglion of a Stomatopod, Squilla oratoria

From somata of the pacemaker neurons in the Squilla heart ganglion, pacemaker potentials for the spontaneous periodic burst discharge are recorded with intracellular electrodes. The electrical activity is composed of slow potentials and superimposed spikes, and is divided into four types, which are: (a) "mammalian heart" type, (b) "slow generator" type, (c) "slow grower" type, and (d) "slow deficient" type. Since axons which are far from the somata do not produce slow potentials, the soma and dendrites must be where the slow potentials are generated. Hyperpolarization impedes generation of the slow potential, showing that it is an electrically excitable response. Membrane impedance increases on depolarization. Brief hyperpolarizing current can abolish the plateau but brief tetanic inhibitory fiber stimulation is more effective for the abolition. A single stimulus to the axon evokes the slow potential when the stimulus is applied some time after a previous burst. Repetitive stimuli to the axon are more effective in eliciting the slow potential, but the depolarization is not maintained on continuous stimulation. Synchronization of the slow potential among neurons is achieved by: (a) the electrotonic connections, with periodic change in resistance of the soma membrane, (b) active spread of the slow potential, and (c) synchronization through spikes.