Long term incubation of cardiac myocytes with oleic acid and very-low density lipoprotein reduces heparin-releasable lipoprotein lipase activity

An exogenous [³H]triolein emulsion was hydrolyzed by intact cardiac myocytes with functional LPL located on the cell surface. This surface-bound LPL could be released into the medium when cardiac myocytes were incubated with heparin. Incubation of cardiac myocytes with VLDL, or the products of TG breakdown, oleic acid or 2-monoolein, did not increase LPL activity in the medium. However, incubation of cardiac myocytes with either VLDL or oleic acid for > 60 min did reduce heparin-releasable LPL activity. In the heart, this inhibitory effect of FFA could regulate the translocation of LPL from its site of synthesis in the cardiac myocyte to its functional site at the capillary endothelium.Abbreviations LPL lipoprotein lipase - TG triacylglycerol - FFA free fatty acids - VLDL very-low density lipoprotein     

Anatomical differences involving the archicortex and the neocortex of male and female brains: A quantitative syudy of 20 brains of each sex

The relative sizes of the brain stem, cerebellum, diencephalon, archicertex and neocortex were investigated in twenty brains of each sex, by determining the percentages of average total brain weights in each case. The differences between the left and the right cortical regions were also compared. The neo-archicortical ratio was found to be smaller in females than in males. Significantly heavier right neocortex occurred in males than in females. Weight predominance of the right archicortex was found in both sexes. These findings are suggestive that anatomical differences may contribute to the behaviour pattern differences occurring between male and female.     

Two major classes of mitogen-reactive B lymphocytes defined by life span

The relative numbers of short- and long-lived mitogen-reactive B cells in the peripheral pool were evaluated by studying the decay of lipopolysaccharide (LPS)-reactive B lymphocytes in LPS nonresponder, histocompatible hosts for periods of up to 3 wk after cell transfer. The results obtained demonstrate the existence of two major classes of mitogen-reactive B cells defined by life span. The "short-lived" cell component comprises about 80 to 90% of the reactive cells and decays with a life expectancy of 18 to 24 hr. The long-lived cell component, with life expectancies of 10 to 20 days, comprises about 10 to 20% of the reactive cells and is preferentially enriched in circulating B cells. The present ratio for short- and long-lived B cells implies a highly dynamic state for the immune system which must be advantageous in the selection of available repertoires.     

Life span of B lymphocytes: the experimental basis for conflicting results

Recent claims have challenged the view that most peripheral, mature B cells are long-lived, and propose rates of peripheral decay that are compatible with bone marrow production. This disagreement can only reflect differences in the protocols and methods used to measure peripheral lymphocyte life spans. We have now assessed toxic or other nonselective effects of hydroxyurea treatment on the survival and migration of peripheral, noncycling cells, as well as possible reasons for exaggerated decays of LPS-reactive B cells transferred to LPS nonresponder hosts, the two methods leading to conclusions of short life spans. We also studied general effects on cell survival introduced by either repeated [3H]thymidine injections or the stress associated with surgery, thoracic duct cannulation in particular--methods with which the notion of long life spans had been established. The results failed to show toxic or nonselective effects of hydroxyurea treatments and artificial decays of LPS-reactive cells in adoptive hosts. In contrast, the present experiments demonstrate that both the stress associated with surgery and repeated [3H] thymidine administration profoundly deplete a pool of short-lived B cells, consequently selecting for an apparent higher proportion of long-lived cells.     

Principal-components analysis of Brazilian Indian anthropometric data

Analysis of nine characteristics on 1,205 males and 932 females from 12 tribes or groups of tribes indicated a poor relationship between morphology and language, as well as moderate agreement with the variability expected considering geography only. Two samples in the Xingu area studied during an interval of half a century (1897-1947) showed remarkable similarity. The conformity of the Caingang morphology with those of other tribes and the distinctiveness of the Xavante and Tenetehara has been amply confirmed.     

Lack of correlation between loss of anchorage-independent growth and levels of transformation-specific p53 protein in retinoic acid-treated F9 embryonal carcinoma cells

It has been shown that differentiated derivatives of retinoic acid (RA)-treated F9 embryonal carcinoma cells become non-malignant. In the present study it is asked whether this loss of malignancy is due to cellular differentiation. Because the ability of cells to grow in suspension correlates with in vivo tumorigenicity, we determined the time course of the loss of this property, after RA treatment, with relation to the differentiation to parietal endoderm and the acquisition of normalcy in several common transformation-specific properties of F9 cells. Our results show that pretreatment with RA for 24 h caused 80% inhibition of anchorage-independent growth in F9 cells, and this inhibition reached its highest level (98%) after pretreatment with RA for 48 h and longer. However, all other observed transformation-related properties, and the levels of plasminogen activator (marker for parietal endoderm) remained unaltered at this early post-treatment stage. These observations suggest that the loss of malignancy is a relatively early event in the biochemical pathways involved in the RA-induced differentiation of F9 cells. Furthermore, our data show that the presence of elevated levels of p53 alone may not be sufficient to maintain the anchorage-independent growth and the rapid proliferation of F9 cells.     

Sustained sensitivity modifications induced by brief length perturbations in the crayfish slowly adapting stretch receptor

These experiments in the slowly adapting stretch receptor of crayfish test the effects of brief length perturbations (i.e., pulses) when presented in isolation at different constant elongations or superimposed on trapezoidal stretches of different amplitudes. Within "in vivo" lengths, during static responses, perturbations reduced firing rates to below control values and, in extreme cases, could silence the receptor. This effect, or "down-step," was sustained, occurred above a threshold pulse amplitude and background stretch, and increased with both stimulus characteristics, but was not present during dynamic responses. Beyond "in vivo" lengths, and in a few cases within those limits but close to the extremes, the receptor was silent but perturbations could restore activity. Lengthening pulses were more effective than shortening ones in generating after-effects. Perturbations change, during indefinitively long periods, the receptor's length or static sensitivity acting as a negative feedback which tends to maintain the discharge rate within fixed values. Perturbations disclose marked nonlinearities, which suggest that the classical view of a proportional control in the reflex loop in which the receptor participates may not operate in natural conditions.     

Nucleotide sequence of the glnA-glnL intercistronic region of Escherichia coli

The nucleotide (nt) sequence of a 682-bp fragment containing the 3' end of the glnA gene, the region between the glnA and glnL genes, and the 5' end of the glnL gene from Escherichia coli was determined. This segment contains the region coding for the last 107 amino acids (aa) of glutamine synthetase, including the adenylylation site of this enzyme. The analysis of this sequence revealed two REP sequences, a Rho-independent terminator, the putative glnL promoter and the possible binding site for the glnG product, NRI.