The interaction between chronic ethanol consumption and oxygen tension in influencing the energy state of rat liver.

Hepatocytes were isolated from chow-fed and liquid-diet control rats, and animals fed ethanol chronically for 31 days. These preparations were analyzed for adenine nucleotide and inorganic phosphate concentrations after being maintained under various conditions of oxygenation and nutrient availability. Hepatocytes from ethanol-fed animals resuspended at high cell density (oxygen tensions near zero) demonstrated a greater depression in cellular energy state as indicated by decreases in phosphorylation potential and energy charge. If, however, these hepatocytes were restored to high oxygen tension their energy state was equivalent to that observed with preparations from liquid-diet control animals. Moreover, their rate of oxygen consumption was equivalent to that of control hepatocytes. Analyses of livers from chow-fed, liquid diet control, and ethanol-fed rats which were freeze-clamped while being perfused by the animal's blood revealed that there were no significant differences in the energy states of the hepatic tissue from these three animal groups. These results indicate that (1) the hepatic energy state in rats fed ethanol chronically is maintained under conditions of normal oxygen tension and (2) that hepatic tissue from these animals experiences a much more dramatic depression in energy state than tissue from control rats when subjected to oxygen deprivation.

Distribution of [3H]zolpidem binding sites in relation to messenger RNA encoding the alpha 1, beta 2 and gamma 2 subunits of GABAA receptors in rat brain.

Localization of the messenger RNAs that encode the alpha 1, beta 2 and gamma 2 subunits of GABAA showed a distinct topographic pattern in rat brain which corresponded with [3H]zolpidem binding in most brain regions. The close topographic correspondence between the specific receptor subunits examined and the distribution of [3H]zolpidem binding sites provides support for the hypothesis that this benzodiazepine type 1 selective ligand binds to a GABAA receptor that consists of alpha 1, beta 2 and gamma 2 subunits in the rat brain. Brain regions with relatively high densities of alpha 1, beta 2 and gamma 2 subunits of GABAA and [3H]zolpidem binding included olfactory bulb, medial septum, ventral pallidum, diagonal band, inferior colliculus, substantia nigra pars reticulata and specific layers of the cortex. Two areas with low [3H]zolpidem binding and a virtual absence of these GABAA receptor subunit messenger RNAs were the lateral septum and the striatum. In contrast to the discrete pattern observed for alpha 1 and beta 2 subunit messenger RNAs, the gamma 2 subunit messenger RNA was distributed more diffusely in brain. Only the hippocampus, layer 2 of the piriform cortex and the cerebellum showed a strong concentration of the gamma 2 subunit messenger RNA. It was determined with a polymerase chain reaction assay that both long and short variants of the gamma 2 subunit messenger RNAs were present within several of the brain sites selected for examination. Sites with high densities of [3H]zolpidem binding sites had a greater relative abundance of the gamma 2 long splice variant, compared to the gamma 2 short variant. There were some regions that expressed high levels of alpha 1, beta 2 and gamma 2S subunit messenger RNAs but low [3H]zolpidem binding, suggesting that gamma 2 splice variant expression may modulate high-affinity [3H]zolpidem binding. To determine relationships between in vitro [3H]zolpidem binding and functional sensitivity in vivo, interactions between zolpidem and GABA were assessed in brain regions that contained high and low densities of [3H]zolpidem binding sites. In the medial septum, a brain region with a high concentration of [3H]zolpidem binding sites, iontophoretic application of zolpidem enhanced the inhibitory effect of GABA responses on 70% of the neurons examined. In the lateral septum, which contains very low densities of [3H]zolpidem binding sites, neurons were not sensitive to zolpidem enhancement of GABA-induced inhibition. These electrophysiological results demonstrate a correspondence between the regional distribution of [3H]zolpidem binding in vitro and functional sensitivity to the drug in vivo.

The frequency of the delta F508 mutation in the cystic fibrosis genes of 71 unrelated South African cystic fibrosis patients.

The common delta F508 mutation is present in approximately 70% of mutant cystic fibrosis (CF) genes of European and North American populations. The frequency of the delta F508 mutation has been established for two groups of South African CF subjects. The mutation was found to be present in 82% and 53% of CF genes of white and coloured (i.e. of mixed ancestry) subjects respectively. These findings assist in providing appropriate counselling to individuals who have a family history of CF and in defining laboratory strategies for the establishment of an efficient genetic service for cystic fibrosis.

Differential effects of chronic ethanol administration on GABA(A) receptor alpha1 and alpha6 subunit mRNA levels in rat cerebellum.

Chronic ethanol exposure alters muscimol, pentobarbital, and benzodiazepine agonist and inverse agonist effects on the function of GABA(A) receptor-gated Cl(-) channels in the central nervous system (CNS). We have recently shown that prolonged ethanol inhalation reduces the expression of GABA(A) receptor alpha1 and alpha2 subunit mRNAs in the rat cerebral cortex, with no effect on the level of alpha3 subunit transcripts, glutamic acid decarboxylase mRNA levels, or poly(A)(+) RNA levels. In the present study, rats were administered alcohol by liquid diet for 2 weeks using a pair-fed design. GABA(A) receptor alpha subunit mRNA levels were quantified by Northern analysis using specific cRNA probes. GABA(A) receptor alpha1 subunit mRNA levels were reduced in the cerebral cortex to the same extent as previously reported following prolonged ethanol inhalation. In the cerebellum, chronic ethanol ingestion reduced the levels of GABA(A) receptor alpha1 subunit mRNAs (4.8 and 4.4 kb) by 20-30% and increased the levels of GABA(A) receptor a6 subunit mRNA (2.7 kb) by 45%. GABA(A) receptor alpha2 and alpha3 subunit mRNAs were not detected in the cerebellum. Glutamic acid decarboxylase mRNA levels as well as poly(A)(+) RNA levels were not significantly altered following chronic ethanol exposure by liquid diet. Acute ethanol administration had no effect on GABA(A) receptor a6 subunit mRNA levels. However, acute administration of both Ro15-4513 and its vehicle control altered GABA(A) receptor alpha6 subunit mRNA levels in the cerebellum. Since GABA(A) receptor alpha6 subunits contain recognition sites for Ro15-4513, an inverse agonist, and an ethanol antagonist, the elevation in the expression of these subunits following chronic ethanol ingestion may account for increased sensitivity to inverse agonists after chronic ethanol administration and possibly contribute to the withdrawal syndrome. These data also suggest that chronic ethanol exposure regulates GABA(A) receptor gene expression by differential effects on the synthesis of specific subunits of GABA(A) receptors in the CNS.

Gaucher's disease in the Cape coloured population of the RSA, including a family with 5 affected siblings.

Nine Cape Coloured children from 4 families with severe non-neuropathic Gaucher's disease are documented. The diagnosis was confirmed histologically in the bone marrow, spleen and liver, and by serum acid phosphatase and leucocyte beta-glucosidase assays. This represents a minimum prevalence for Gaucher's disease of 1 in 247,350 in this population and an approximate genetic carrier rate of 1 in 230 for the abnormal gene. A family with 5 affected siblings is recorded. The severe early clinical expression documented in these coloured patients is similar to that described in the Afrikaner population and differs from the less severe expression of Gaucher's disease in the South African Ashkenazi Jewish population. Gaucher's disease in the Cape Coloured population presents with a precocious onset, causes severe complications and progresses rapidly.

Molecular basis for regionally specific action of ethanol on gamma-aminobutyric acidA receptors: generalization to other ligand-gated ion channels.

The present investigation provides evidence that there is neuroanatomical specificity for ethanol enhancement of gamma-aminobutyric acid (GABA)-induced inhibition in mammalian brain and that the expression of a specific GABAA isoreceptor is associated with this regional action of ethanol. Ethanol enhanced responses to iontophoretically applied GABA in the medial septum, inferior colliculus, substantia nigra reticulata, ventral pallidum and the diagonal band of Broca. In contrast to these results, responses to GABA applied to cells in the lateral septum, ventral tegmental area and the hippocampus were not affected by ethanol. In those brain regions where ethanol enhanced responses to GABA, a high concentration of zolpidem binding was found, whereas zolpidem binding was much lower or absent in brain regions where ethanol did not enhance GABA. These observations support the hypothesis that ethanol enhances GABA within specific regions of brain by affecting a GABAA receptor with specific structural components. From data obtained with in situ hybridization, there was a strong relationship between the regional distribution of zolpidem binding and the expression of specific mRNAs for the alpha-1, beta-2 and gamma-2 GABAA receptor subunits at sites where ethanol enhanced responses to GABA. The mRNA for the long and short variants of the gamma-2 subunit were found in brain regions both sensitive and insensitive to the action of ethanol on GABA-induced inhibition. These data were not able to address whether the gamma-2 long variant in combination with the alpha-1 and beta-2 subunits is essential for ethanol enhancement of responses to GABA. However, the observation that the long version of the gamma-2 subunit is present in brain areas where ethanol did not affect GABA function suggests that the presence of the long variant of the gamma-2 subunit alone is not sufficient for ethanol's action to enhance responses to GABA. Rather it is concluded that the appropriate combination of GABAA receptor subunits is critical for this action of ethanol. Because the GABAA receptor belongs to a superfamily of ligand-gated ion channels, the action of ethanol was examined on responses to agonists acting on receptors linked to other ion channels. As noted for GABA, local application of ethanol altered responses to NMDA, nicotine and glycine when applied to some, but not all, neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Deletion mapping of 39 random isolated Y-chromosome DNA fragments.

Thirty-nine recombinants isolated from a Y chromosome-specific library were deletion mapped. Seven deletion intervals were defined by hybridization of probes to DNA of eight individuals with aberrant Y chromosomes. Extreme cytogenetic limits of the deletion intervals were determined by in situ hybridization of one probe per deletion interval. Five intervals, with a total of twenty-five probes, were allocated to the long-arm euchromatic region. The probes described will be useful for characterization of aberrant Y chromosomes, in searching for expressed sequences on the Y chromosome, and for further study of the evolutionary relationship between the Y chromosome and other chromosomes.

Phenotypic variation among familial hypercholesterolemics heterozygous for either one of two Afrikaner founder LDL receptor mutations.

Two common founder-related gene mutations that affect the low-density lipoprotein receptor (LDLR) are responsible for approximately 80% of familial hypercholesterolemia (FH) in South African Afrikaners. The FH Afrikaner-1 (FH1) mutation (Asp206-->Glu) in exon 4 results in defective receptors with approximately 20% of normal activity, whereas the FH Afrikaner-2 (FH2) mutation (Val408-->Met) in exon 9 completely abolishes LDLR activity (< 2% normal activity). We analyzed the contribution of these mutations and other factors on the variation of hypercholesterolemia and clinical features in Afrikaner FH heterozygotes. The type of FH mutation, plasma triglyceride levels, and age of patients each contributed significantly to the variation in hypercholesterolemia, whereas smoking status, high-density lipoprotein cholesterol levels, and gender had no influence. Although all FH heterozygotes had frank hypercholesterolemia, patients with the FH1 mutation had significantly lower cholesterol levels than those with the FH2 mutation. FH1 heterozygotes also tended to have milder clinical features. The differences between the two FH groups could not be explained by a difference in the common apolipoprotein E variants. This study demonstrates that mutational heterogeneity in the LDLR gene influences the phenotypic expression of heterozygous FH.