Action of amino acids and convulsants on cerebellar spontaneous action potentials in vitro: effects of deprivation of C1-, K+ of Na+

(1) The inhibition of spontaneous action potentials in guinea pig cerebellar cortex slices by GABA, glycine, taurine and beta-alanine is maintained when C1- in the superfusion medium is almost completely replaced by NO3- or I-('permeant' anion), but the inhibition decreases in magnitude with repeated application of the amino acid. Replacement of C1- by sulfate or isethionate ('impermeant' anion) causes a conversion of inhibition by these amino acids to excitation. The initial excitation which is sometimes seen with these inhibitory amino acids in high C1- media is abolished when C1- is replaced by either permeant or impermeant anions. (2) Reduction of K+ in the medium causes an increase of inhibition by the inhibitory amino acids in the presence of high C1- and reduction of excitation when C1- is replaced by impermeant anion. (3) Excitation by GABA in impermeant anion (low C1-) media is unaffected by reduction of Na+ in the media by 50% but excitations by glycine, taurine, beta-alanine and L-glutamate are greatly reduced. (4). Excitation by GABA in impermeant anion (low C1-) media is abolished by picrotoxin and bicuculline which both suppress inhibition by GABA in a high C1- medium. Strychnine suppresses the effects of glycine, taurine and beta-alanine in either a low or high C1- medium. Bicuculline blocks the inhibitory effect of these three amino acids in a high C1- medium but does not affect their excitatory effects in a low C1- medium. (5) These results are consistent with the hypothesis that the inhibitory amino acids, GABA, glycine, taurine and beta-alanine, cause inhibition via increase of C1- (and perhaps K+) permeability and that glycine, taurine and beta-alanine also interact with strychnine-sensitive receptors mediating (perhaps indirectly) increased permeability to Na+ and, therefore, excitation in low C1- media.     

Organochlorine and mercury residues in the harp seal (Pagophilus groenlandicus)

Samples of blubber, liver, kidney and brain, obtained from 10 male, 6 female neonatal, and 4 lactating female harp seals (Pagophilus groenlandicus), were analysed for DDT, dieldrin, PCB, and total mercury. Methyl mercury levels in blood were also determined. Biocide deposition was not significantly different in female and male ten day old pups. There were no significant differences in biocide levels in the liver of the 14/+ day old males, but in blubber there were significant differences in dieldrin and DDT. There was no clear relationship between biocide levels in the 6-18 year old lactating adults and their pups. Younger adult seals (6 and 7 years) were found to have higher levels of PCB and sigmaDDT levels in their blubber than did older females (10 and 18 years). Wide intraspecific variation was noted in organochlorine and mercury residue levels. Pups taken in 1973 were found to have lower organochlorine residues than pups taken in the same area in 1971. Preliminary investigation indicates that detectable amounts of organochlorine and mercury residues are capable of crossing the placenta in the harp seal.     

Nature of the Thermal pretransition of synthetic phospholipids: dimyristolyl- and dipalmitoyllecithin

The hydrated synthetic lecithins, dimyristoyl and dipalmitoyllecithins, undergo two thermal transitions, a broad low enthalpy "pretransition" prior to the sharp first-order "chain-melting" transition. Both phospholipids exhibit the same temperature-dependent structural changes associated with the thermal pretransition. At low temperatures, below the pretransition, a one-dimensional lamellar lattice is observed. The hydrocarbon chains are fully extended and tilted with respect to the plane of the lipid bilayer. The hydrocarbon chain packing displays a temperature dependence and the angle of tilt of the hydrocarbon chains decreases with increasing temperature, reaching a minimum value of 30 degrees at the pretransition temperature of both lecithins. The pretransition is associated with a structural transformation from a one-dimensional lamellar to a two-dimensional monoclinic lattice consisting of lipid lamellae distorted by a periodic ripple. The hydrocarbon chains remain tilted in the temperature range intermediate between the pretransition and chain-melting transition. The cell parameters of this two-dimensional lattice exhibit a compositional dependence. The a parameter (proportional to the lamellar repeat distance) increases with increasing water content, while the b parameter (a measure of the ripple periodicity) decreases with increasing water content. At the chain-melting transition, the hydrocarbon chains of the phospholipid melt and assume a liquid-like conformation and the lattice reverts to one-dimensional lamellar. These structural changes observed for dimyristoyl- and dipalmitoyllecithins may be a common feature of all synthetic lecithins exhibiting a thermal pretransition. The appearance of the pretransition and accompanying two-dimensional may arise from specific interactions between the choline moiety of the polar head group and the structured water matrix surrounding it.     

Artificial feeding of Black infants

Analysis of milk formula feeds in a community where infant malnutrition is common, showed that overdilution of feeds is less frequent than expected. Many feeds were too concentrated. Modified and 'humanised' milks were more often and more seriously too strong than unmodified milks. An inadequate number and volume of milk feeds per day was probably more important in causing malnutrition than the strength of the feeds.     

The effect of intermittent carbon monoxide exposure on experimental atherosclerosis in the rabbit

(1) Twenty-four female New Zealand White rabbits were fed commercial diet plus 2% cholesterol. Twelve of these animals were exposed to carbon monoxide for 4 hours per day, seven days per week for 10 weeks. The carbon monoxide exposure was such that the mean blood carboxy-haemoglobin was raised to approximately 20% during each exposure period. Twelve control animals breathed atmospheric air under the same conditions of confinement as the carbon monoxide-exposed group. (2) No significant differences in the plasma levels of cholesterol, triglycerides or glutamate oxalacetate transaminase were observed between the two groups during the experiment. (3) When the animals were sacrificed at the end of the experiment no significant differences were observed between the two groups in the aortic content of triglycerides, cholesterol or phospholipids. (4) The extent of coronary artery atherosclerosis was statistically significantly higher in the carbon monoxide group than in the control group. (5) Ultracentrifugal analysis of plasma lipoproteins revealed that there was significantly more cholesterol in the d less than l.006 fraction from the CO-exposed rabbits. (6) These findings, are discussed with particular reference to the claim that the causal agent in tobacco smoke associated arterial disease is carbon monoxide.     

The cell surface of Trypanosoma musculi bloodstream forms. II. Lectin and immunologic studies

Report is given on a metabolic investigation with non-radioactive and 14C-labelled methiothepin(1-[10',11'-dihydro-8'-(methylthio)-dibenzo mean value of b,f thiepin-10'yl]-4-methyl-piperazine) in rat, dog, and man. After i.p. and oral administration of the drug to the rat, the metabolites of methiothepin were excreted fecally. In the same species, a considerable biliary secretion of the compounds has been demonstrated. In dog and in man, excreted metabolites have been found both in urine and feces after oral application of the drug. The biotransformation of methiothepin within the species investigated proceeds via hydroxylation, sulfoxidation, O-methylation, N-demethylation, N-oxidation and formation of conjugates. The large number of metabolites is due to the various sites of action within the molecule, that are accessible to in vivo oxidation. Of a large number of isolated positionally isomeric compounds, merely the basal structures could be clarified. Possibly the mode of biotransformation to which methiothepin is subjected in the organism, proves determinant for the way of excretion. In the rat, all metabolites are hydroxylated and reach the intestinal tract as conjugates with the bile. In dog and man, however, non-hydroxylated, sulfoxidized metabolites were likewise found, which were excreted mainly renally in both species.     

Cytogenetic variants in holoprosencephaly. Report of a case and review of the literature

A new infant with classical features of holoprosencephaly and multiple extracranial malformations was found to have abnormal karyotype: 47, XX, + 13. Although trisomy D has been reported in a few cases, our case is the first, to our knowledge, in which positive identification of trisomy 13 was made by banding technique in cebocephaly.     

Diazepam-ketamine anaesthesia for open heart surgery "micro-mini" drip administration technique

Two hundred open heart cases anaesthetized with a combination of diazepam-ketamine using "Micro-Mini" drip administration technique were presented. The results were eminently desirable, and in the opinion of the authors are a notable improvement over other methods for all types of cardiovascular surgery including most advanced heart diseases. The advantages of this anaesthetic method for cardiovascular surgery are as follows: 1. Effects on cardiovascular system are minimal.--2. Respiratory depression is negligible.--3. There is no increase in salivation or muscle tone.--4. Induction and maintenance of anaesthesia are simple and smooth.--5. Anaesthesia can be maintained, using a high concentration of oxygen alone, by a slight increase in rate of ketamine administration whenever necessary.--6. Post-anaesthetic psychotomimetic effects are negligible.--7. Nearly 100% of patients have excellent amnesia.--8. It has a wide margin of safety.--9. This technique has proved highly acceptable to patients and surgeons. We feel ketamine should be used in small dosages continuously administered with either "Micro-Mini" drip infusion or infusion pump. Ketamine given in this fashion should be regarded as an analgesic.     

Endodermal sinus tumor and embryonal carcinoma of the ovary in a 53-year-old woman

BACKGROUND: Germ cell tumors, the most common ovarian malignancies in females under the age of 21, are rare in older women. We report an unusual case of a mixed embryonal carcinoma and endodermal sinus germ cell tumor in a perimenopausal patient and review the differential diagnosis and management of these malignancies with respect to age. CASE: A 53-year-old woman complaining of irregular menses and pelvic pain was found to have a large pelvic mass and a positive pregnancy test. Subsequent investigation revealed a large left adnexal mass, and an elevated beta-HCG and alpha-AFP. At laparotomy, a mixed germ cell tumor was found. The patient was treated with multiagent chemotherapy and currently is without evidence of disease. CONCLUSION: Although rare, the diagnosis of germ cell tumor should be considered in older women presenting with a large pelvic mass. The treatment and prognosis is similar regardless of age, except that reproductive-sparing surgery is not a priority in the older patient.