Uptake and metabolism of fatty acids and analogues by cultured cardiac cells from chick embryo

Cultured heart cells from chick embryo, present as a confluent monolayer in a minimal medium, take up labelled fatty acids (from C6 to C22) bound to serum albumin with a rapid incorporation into neutral and complex lipids (visible at 15 s), while beta-oxidation is delayed (visible at 15 min). Fatty acids enter the cardiac cells through two mechanisms, one involving a readily saturable process, the other resembling passive diffusion. The saturable transport system recognizes fatty acids with a high affinity, Km from 4.5 to 16 muM. The V is from 0.03 to 0.3 nmol of fatty acid incorporated min-1 (10(6) cells)-1. Competitive inhibition occurs between fatty acids while glucose, aminoacids and lactate do not compete with palmitate for the entry into the cells. The analysis of unesterified fatty acids from the usual culture medium and from the cells show a gradient of concentration up to 54-fold; moreover experiments performed in minimal medium at 20 degrees C show that fatty acids accumulate up to 28-fold in the cells. Efflux rates can be measured after loading the cells at 20 degrees C; the curves are bimodal and the pseudo first-order rate constants thus determined are in the order of 0.5 min-1, as opposed to 2.5 to 5.0 min-1 for the passive-diffusion component calculated for the influx rates. Studies on the role of serum albumin at constant and at variable fatty acid-albumin molar ratios indicate that the rate of uptake is controlled by the total fatty acid concentration and not solely by the concentration of unbound fatty acids. No labelled fatty acid was found to be bound to the cytoplasmic fraction supposed to contain the fatty acids-binding protein; our results are in favour of the presence of a specific transport system for fatty acids either at the level of subcellular organelles or more likely at the surface of cardiac cells.

Effect of lithium and other alkali metals on brain chemistry and behavior. II. Intracranial self-stimulation behavior

Rats implanted with bipolar electrodes aimed at the medial forebrain bundle (MFB) were trained to self-stimulate. Six daily injections of 2 mEq/kg of the chloride salts of Li+, Rb+ or Cs+ were administered and the rate of intracranial self-stimulation (ICSS) was recorded. Lithium caused a reversible decrease in ICSS rate, beginning on the second day and returning to pretreatment rate on the fourth day of injections. The decrease was more pronounced in animals with high baseline rate (over 500 responses/10 min) than in low responders. Rubidium enhanced ICSS rate whereas cesium had no effect. These results agree with other accumulating data showing the opposite effects of Li+ and Rb+, but their relevance to effective disorders is not clear.

The effects of dark isolation on the performance of a white-black discrimination task in the rat

Four experiments were performed on rats using a white-black discrimination task. In Exp. 1 the animals that were isolated in darkness for four hours after each learning trial performed with fewer errors than the animals that spent the same posttrial periods in enriched environments in groups. In Exp. 2 training was carried further and retention after 10 days was investigated. The isolated animals again performed with fewer errors. In Exp. 3 a control was added to the Isolated and Enriched conditions. Animals in the control group were returned to their home cages after each training trial. No difference was found between Enriched and Control animals. In Exp 4 Dark-Isolated, Light-Isolated, Dark-Crowded and Light-Crowded groups were used. The performance of the two Dark-treated groups was superior to that of the Light-treated groups. The findings are discussed with reference to interference and consolidation theory.

Mycobacterial antigens in antibody responses of leprosy patients

A reference system for M. smegmatis antigens in crossed immunoelectrophoresis was used to study antibody activities in serum samples of 91 leprosy patients. All polar and borderline lepromatous patients were positive. Mean numbers out of 14 M. smegmatis antigens involved were 4.3 and 3.5, respectively. Precipitins against antigen no. 1 were seen in all lepromatous cases. Antibodies against this antigen were detected in 50% of tuberculoid (polar, subpolar and borderline) cases. Antibody activity against M. avium and M. duvalii antigens was also detected using a staphylococcal radio-immuno-assay. Borderline and polar lepromatous cases showed elevated levels. Antigenic comparisons were made between four slow growing mycobacteria, fourteen fast growing mycobacteria and the leprosy bacillus using lepromatous serum pools as antibody reagents. Four of the antigens detected in M. leprae were also found in slow growing as well as fast growing species indicating a common occurrence among mycobacteria. Antigen no. 1 of M. duvalii, with an apparent molecular weight of 290,000, showed nonprotein characteristics. Further analysis of antigen no. 21, using lepromatous serum pools as antibody reagents, indicated the existence of at least two groups of antigenic determinants. In addition to determinants shared by all mycobacteria, there were antigenic structures apparently unique to M. leprae.

In vivo measurement of variations in the oxygen 18 content of water in rat brain

A method of analysis for oxygen 18 is described, based on the anodic oxidation of specially prepared tantalum wires implanted through cannulas into the tissue of living animals. The thin anodic oxide layer formed on these wires is then analyzed by the 18O(p,alpha)15N reaction. The isotopic oxygen concentration of water in the brain obtained by this method compares very well with the values obtained by conventional analysis using mass spectrometry. This in vivo method of nuclear microanalysis has been used in both metabolic and equilibration experiments involving oxygen 18. The half-life for the turnover of 18O in body water was found to be about 3 days. A simple three-pool model is presented which can account for the experimental results obtained from the dilution by body water of interperitoneally injected water highly enriched in 18O.

The level of GABA in the brain and locomotor behavior

GABA content was measured in the brains of animals injected with AOAA, DPA or Saline. Significant increases in GABA were found in the motor cortex and cerebellum after treatment with both drugs as compared to saline injected controls. Increased GABA levels were associated with interference with the smooth execution of locomotor acts, especially where balancing and coordination of the hind limbs were necessary.

Amyloid-related serum component (protein ASC) IN LEPROSY PATIENTS

The presence of amyloid-related serum component, protein ASC, in serum samples from 63 leprosy patients was investigated. Protein ASC was detected in 38% of the patients. A correlation to the disease spectrum of leprosy was apparent: polar lepromatous cases, 64% positive; borderline lepromatous, 50%; borderline tuberculoid, 36%; subpolar tuberculoid, 17%; and polar tuberculoid, negative. Antibody activity against the a antigen of Mycobacterium leprae was also determined, showing a similar correlation to the disease spectrum. Serum samples from 23 apparently healthy Ethiopians serving as controls showed a protein ASC incidence of 22%. This figure is significantly higher than the frequency found by others among healthy Norwegian blood donors. Immunoglobulin M levels among patients were elevated in the borderline lepromatous and poplar lepromatous groups. The three tuberculoid groups did not differ in this respect from the control group but were all elevated as compared to a normal Caucasian serum pool. Although raised immunoglobulin M levels seemed to parallel increased frequencies of protein ASC in the patient groups as well as in controls, this correlation might be only secondary to a primary derangement in T-cell function.

In vivo measurement of 32P in the brain of a freely moving rat

A new method for measuring the uptake of materials labeled with radioactive phosphorus (32P) in the brain of a freely moving rat is described. The rate of uptake in the brain of a single animal of 32P-labeled phosphate was compared to the uptake rate in the animal's blood or liver. A comparison was made between the uptake following an intravenous (IV) or an intraperitoneal (IP) injection. The effect of convulsions caused by injections of metrazol on the kinetics of 32P uptake in the brain is described.