Genes for alkaline protease and neutral protease from Bacillus amyloliquefaciens contain a large open reading frame between the regions coding for signal sequence and mature protein

The genes for alkaline protease (apr[BamP]) and neutral protease (npr[BamP]) from Bacillus amyloliquefaciens have been isolated and expressed in Bacillus subtilis. The DNA sequences of apr[BamP] and npr[BamP] revealed, in each case, the presence of a large open reading frame. The inferred amino acid sequence of either gene contained a signal sequence and an additional polypeptide sequence ('pro' sequence) preceding the mature protein. Based on DNA sequence, the start point of translation has been identified as amino acid residue - 107 for apr[BamP] and -221 for npr[BamP]. To demonstrate that the start point of translation of apr[BamP] in vivo is probably at codon -107, codon -103 (AAA) was changed to an ochre (TAA) by site-directed mutagenesis. Alkaline protease was produced from this ochre mutant derivative of apr[BamP] only when the host strain was Su+. The presence of a pro sequence may be common to all of the secreted proteases from bacilli.

Neurosteroids: 3 alpha-hydroxy-5 alpha-pregnan-20-one and its precursors in the brain, plasma, and steroidogenic glands of male and female rats

A RIA procedure for measuring progesterone (PROG), 5 alpha-pregnane-3,20-dione (5 alpha-DH PROG), and 3 alpha-hydroxy-5 alpha-pregnan-20-one (3 alpha,5 alpha-TH PROG) has been developed and validated by GLC/mass spectrometry. Measurements were made in intact and adrenalectomized (ADX) male rats, in cyclic, pregnant, spayed, and spayed-ADX females, and in both males and spayed females injected with PROG. The predominant contribution of the ovary to the concentrations of 3 alpha,5 alpha-TH PROG in plasma and brain, was indicated by its larger levels in females, in particular during pregnancy, and by its presence in ovarian tissue and disappearance after ovariectomy. An additional adrenal origin in both males and females was shown. Neither PROG nor 5 alpha-DH PROG disappeared from brain, contrary to plasma, after combined adrenalectomy and gonadectomy, thus suggesting that PROG might be synthetized de novo in brain. However, the concentrations of 3 alpha,5 alpha-TH PROG in plasma and brain of female rats were positively correlated with the concentrations of PROG in plasma, indicating that plasma PROG was the major precursor of 3 alpha,5 alpha-TH PROG. The direct formation of 3 alpha,5 alpha-TH PROG from PROG in brain was strongly suggested by the increased 3 alpha,5 alpha-TH PROG/PROG ratios in brain vs. plasma, when measured in control females, and after injection of PROG to both males and OVX females. It was previously reported that 3 alpha,5 alpha-TH PROG is a sedative/anxiolytic steroid, as a result of its binding to gamma-aminobutyric acid (GABA)A receptors and allosteric potentiation of GABAcergic neurotransmission. Its concentrations in brain reach indeed the neuroactive range in cyclic and pregnant females, and are compatible with a physiological role of this neurosteroid.

Sequence and expression of a frog brain complementary DNA encoding a kainate-binding protein

Excitatory amino acids (EAAs) are important neurotransmitters in the vertebrate central nervous system. Electrophysiological and ligand-binding studies indicate that at least three different receptor subtypes for EAAs exist--N-methyl-D-aspartate, kainate and quisqualate receptor subtypes--on the basis of the preferred agonist of the receptors. We recently purified a kainate-binding protein (KBP) from frog (Rana pipiens berlandieri) brain by domoic acid (a high-affinity kainate analogue) affinity chromatography, and showed that the kainate-binding activity was associated with a protein of relative molecular mass 48,000 (Mr 48 K). The pharmacological properties and the anatomical distribution of KBP were consistent with those of a kainate receptor-ionophore complex. We have now isolated a complementary DNA encoding KBP of Mr 48 K. The deduced amino-acid sequence of the KBP has similar hydrophobic profiles to those found in other ligand-gated ion channel subunits, and shows some amino-acid sequence similarities to the corresponding regions of brain nicotinic acetylcholine receptor subunits. Localization of the KBP messenger RNAs by in situ hybridization histochemistry is compatible with the results of immunohistochemistry and receptor autoradiography studies. COS-7 cells transfected with the cDNA encoding the KBP show high-affinity kainate-binding activity with pharmacological properties similar to those of the biochemically purified KBP. These results provide the first molecular characterization of an EAA-binding site and raise the possibility that the KBP cDNA encodes a ligand-binding subunit of a kainate receptor-ionophore complex.

Fatty acid activation of peroxisome proliferator-activated receptor (PPAR)

Peroxisome proliferators such as clofibric acid, nafenopin, and WY-14,643 have been shown to activate peroxisome proliferator-activated receptor (PPAR), a member of the steroid nuclear receptor superfamily. We have cloned the cDNA from rat that is homologous to that from mouse, which encodes a 97% similar protein. To search for physiologically occurring activators, we established a transcriptional transactivation assay by stably expressing in CHO cells a chimera of rat PPAR and the human glucocorticoid receptor that activates expression of the placental alkaline phosphatase reporter gene under the control of the mouse mammary tumor virus promoter. 150 microM concentrations of arachidonic or linoleic acid but not of dehydroepiandrosterone, cholesterol, or 25-hydroxy-cholesterol, activated the receptor chimera. In addition, saturated fatty acids induced the reporter gene. Shortening the chain length to n = 6 or introduction of an omega-terminal carboxylic group abolished the activation potential of the fatty acid. To test whether a common PPAR binding metabolite might be formed from free fatty acids we tested the effects of differentially beta-oxidizable fatty acids and inhibitors of fatty acid metabolism. The peroxisomal proliferation-inducing, non-beta-oxidizable, tetradecylthioacetic acid activated PPAR to the same extent as the strong peroxisomal proliferator WY-14,643, whereas the homologous beta-oxidizable tetradecylthiopropionic acid was only as potent as a non-substituted fatty acid. Cyclooxygenase inhibitors, radical scavengers or cytochrome P450 inhibitors did not affect activation of PPAR. In conclusion, beta-oxidation is apparently not required for the formation of the PPAR-activating molecule and this moiety might be a fatty acid, its ester with CoA, or a further derivative of the activated fatty acid prior to beta-oxidation of the acyl-CoA ester.

Seroprotection against serogroup C meningococcal disease in adolescents in the United Kingdom: observational study

OBJECTIVE

To determine the persistence of bactericidal antibody titres following immunisation with serogroup C meningococcal glycoconjugate vaccine at age 6-15 years in order to examine changes in persistence of antibodies with age.

DESIGN

Observational study.

SETTING

Secondary and tertiary educational institutions in the United Kingdom.

PARTICIPANTS

Healthy adolescents aged 11-20 years previously immunised between 6 and 15 years of age with one of the three serogroup C meningococcal vaccines.

INTERVENTION

Serum obtained by venepuncture.

MAIN OUTCOME MEASURES

Percentage of participants with (rabbit complement) serum bactericidal antibody titres of at least 1:8; geometric mean titres of serogroup C meningococcal serum bactericidal antibody.

RESULTS

Five years after immunisation, 84.1% (95% confidence interval 81.6% to 86.3%) of 987 participants had a bactericidal antibody titre of at least 1:8. Geometric mean titres of bactericidal antibody were significantly lower in 11-13 year olds (147, 95% confidence interval 115 to 188) than in 14-16 year olds (300, 237 to 380) and 17-20 year olds (360, 252 to 515) (P<0.0001 for both comparisons). Within these age bands, no significant difference in geometric mean titres of bactericidal antibody between recipients of the different serogroup C meningococcal vaccines was seen. More than 70% of participants had received a vaccine from one manufacturer; in this cohort, geometric mean titres were higher in those immunised at aged 10 years or above than in those immunised before the age of 10.

CONCLUSIONS

Higher concentrations of bactericidal antibody are seen five years after immunisation with serogroup C meningococcal vaccine at age 10 years or above than in younger age groups, possibly owing to immunological maturation. This provides support for adolescent immunisation programmes to generate sustained protection against serogroup C meningococcal disease not only for the vaccine recipients but also, through the maintenance of herd immunity, for younger children.

Characterization of human cDNA and genomic clones for glial fibrillary acidic protein

Both a partial cDNA clone and a complete genomic clone have been isolated for human gfa, the gene encoding the major component of astrocyte intermediate filaments, glial fibrillary acidic protein (GFAP). The nucleotide sequence of the entire coding region and 102 bp of the 5' flanking DNA was determined. The mRNA start site was identified by primer extension and probe protection experiments, and a novel in vitro transcription and translation procedure was then used to establish that the first ATG in the mRNA initiates GFAP synthesis. The predicted amino-terminal sequence for human GFAP differs greatly from that previously deduced for mouse GFAP from its gene sequence, despite otherwise high homology. This discrepancy was resolved by determining that the published mouse genomic sequence has an incorrect additional base. The corrected sequence produces strong homology between human and mouse GFAP in their predicted amino acid sequences, and suggests that human and mouse GFAP initiate at homologous positions. The beginning sequence deduced here for both proteins is matched closely by that previously obtained for porcine GFAP by direct sequencing of its amino-terminal end. This supports the protein initiation sites proposed, and also indicates that GFAP is not processed at its amino-terminal end.

Influence of physical and chemical characteristics of diesel fuels and exhaust emissions on biological effects of particle extracts: a multivariate statistical analysis of ten diesel fuels

The emission of diesel exhaust particulates is associated with potentially severe biological effects, e.g., cancer. The aim of the present study was to apply multivariate statistical methods to identify factors that affect the biological potency of these exhausts. Ten diesel fuels were analyzed regarding physical and chemical characteristics. Particulate exhaust emissions were sampled after combustion of these fuels on two makes of heavy duty diesel engines. Particle extracts were chemically analyzed and tested for mutagenicity in the Ames test. Also, the potency of the extracts to competitively inhibit the binding of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to the Ah receptor was assessed. Relationships between fuel characteristics and biological effects of the extracts were studied, using partial least squares regression (PLS). The most influential chemical fuel parameters included the contents of sulfur, certain polycyclic aromatic compounds (PAC), and naphthenes. Density and flash point were positively correlated with genotoxic potency. Cetane number and upper distillation curve points were negatively correlated with both mutagenicity and Ah receptor affinity. Between 61% and 70% of the biological response data could be explained by the measured chemical and physical factors of the fuels. By PLS modeling of extract data versus the biological response data, 66% of the genotoxicity could be explained, by 41% of the chemical variation. The most important variables, associated with both mutagenicity and Ah receptor affinity, included 1-nitropyrene, particle bound nitrate, indeno[1,2,3-cd]pyrene, and emitted mass of particles. S9-requiring mutagenicity was highly correlated with certain PAC, whereas S9-independent mutagenicity was better correlated with nitrates and 1-nitropyrene. The emission of sulfates also showed a correlation both with the emission of particles and with the biological effects. The results indicate that fuels with biologically less hazardous potentials should have high cetane number and contain less PAC and sulfur. The results also indicate that engine factors affect the formation and emission of nitrated PAC.

Glucocorticoid receptor-mediated induction of glutamine synthetase in skeletal muscle cells in vitro

We studied the regulation by glucocorticoids of glutamine synthetase in L6 muscle cells in culture. Glutamine synthetase activity was strikingly enhanced by dexamethasone. The dexamethasone-mediated induction of glutamine synthetase activity was blocked by RU38486 [11 beta-(4-dimethylaminophenyl)17 beta-hydroxy-17 alpha-(prop-1-ynyl)estra-4,9-dien-3-one], a glucocorticoid antagonist, indicating the involvement of intracellular glucocorticoid receptors in the induction process. RU38486 alone was without effect. Northern blot analysis revealed that dexamethasone-mediated enhancement of glutamine synthetase activity involves increased levels of glutamine synthetase mRNA. Increased enzyme activity was specific for glucocorticoids; other steroid hormones were essentially without effect. The induction of glutamine synthetase was selective, in that glutaminase activity was not induced by dexamethasone treatment of L6 cells. Thus, glucocorticoids regulate the expression of glutamine synthetase mRNA in cultured muscle cells via interaction with intracellular receptors. Such regulation may be relevant to control of glutamine production by muscle.

Isolation of a cDNA for rat brain glutaminase

A single phage was isolated from a lambda gt11 rat brain cDNA library by screening with antibodies prepared against rat renal glutaminase. Partial proteolysis of the fusion protein produced by a lysogen of the isolated phage generated a series of immunoreactive peptides that co-migrated with those derived from the purified brain glutaminase. The cDNA has a single open reading frame which encodes 326 amino acids that are in frame with beta-galactosidase. A 72-kDa protein, corresponding in size to the precursor of mitochondrial glutaminase, was immunoprecipitated from the translation products of rat renal mRNA that selectively hybridized to the cDNA. A probe made from the glutaminase cDNA detected an mRNA about 6 kb in length. This mRNA was present in rat brain and normal kidney RNA, increased 6-fold in acidotic kidney RNA, but was not detectable in liver RNA.

Development of an anti-Salmonella typhi Vi ELISA: assessment of immunocompetence in healthy donors

We have developed a solid-phase enzyme-linked immunosorbent assay (ELISA) to study the vaccination responses to Vi capsular polysaccharide of Salmonella typhi (S. typhi Vi) vaccine. Purified S. typhi Vi polysaccharide was biotinylated and bound to streptavidin coated microtitre plates. Reproducibility was determined across a range of IgG antibody levels: mean interassay coefficients of variation (CVs) were <11.9% for non-vaccinated sera with low levels and <11.1% for sera with very high levels of anti-S. typhi Vi IgG. Specificity was assessed by inhibition studies using salmonella antigen. We have developed the ELISA based on normal adult serum responses to test immunization with S. typhi Vi vaccine. We also report here anti-S. typhi Vi IgG levels in a group of healthy preschool children. In non-vaccinated adult sera (n = 104), the median value of anti-S. typhi Vi IgG, expressed in S. typhi Vi arbitrary units (AU/ml), was 5.3 AU/ml and in non-vaccinated sera from children (n = 44) the median value was 1.4 AU/ml. The data from immunization of healthy volunteers (n = 23) show that geometric mean levels of anti-S. typhi Vi IgG were significantly higher (P < 0.0001) for post-vaccination subjects (39.2 AU/ml) compared to paired prevaccination (3.9 AU/ml) values. A total of 21/23 vaccine recipients had <8 AU/ml S. typhi Vi IgG in their sera prior to vaccination and of these 20/21 (95%) exhibited threefold increases and 14/21 (67%) fourfold increases in their S. typhi Vi IgG following vaccination. Based on the data in this study, we propose a threefold increase in anti-S. typhi Vi IgG post-vaccination to be considered a positive vaccination response. The ability to demonstrate clearly an antibody rise in response to immunization with S. typhi Vi capsular polysaccharide vaccine suggests that this is likely to be a useful vaccine for the assessment of B cell function in patients with suspected immune deficiency.

A glutaminase (gis) gene maps to mouse chromosome 1, rat chromosome 9, and human chromosome 2

A rat cDNA clone encoding a portion of phosphate-activated glutaminase was used to identify DNA restriction fragment length polymorphisms (RFLPs) in sets of somatic cell hybrids and between wild-derived and inbred strains of mice. Segregation of rat and mouse chromosomes among somatic cell hybrids indicated assignment to rat chromosome 9 and mouse chromosome 1. Analysis of chromosome 1 alleles for several genes in an interspecific cross between Mus spretus and C3H/HeJ-gld/gld mice indicates that glutaminase can be positioned within 5.5 +/- 2.0 cM proximal to Ctla-4. Similarly, human-hamster somatic cell hybrids were examined for RFLPs, and four human EcoRI restriction fragments were found to hybridize with the rat glutaminase probe. Two of these restriction fragments cosegregated and mapped to human chromosome 2 in a region that is syntenic with mouse chromosome 1 and rat chromosome 9.

Regional localization of the human glutaminase (GLS) and interleukin-9 (IL9) genes by in situ hybridization

Phosphate-activated glutaminase is found in mammalian small intestine, brain, and kidney, but not in liver. The enzyme initiates the catabolism of glutamine as the principal respiratory fuel in the small intestine, may synthesize the neurotransmitter glutamate in the brain, and functions in the kidney to help maintain systemic pH homeostasis. Interleukin-9 (IL9) is a relatively new cytokine that supports the growth of helper T-cell clones, mast cells, and megakaryoblastic leukemia cells. cDNA clones have recently been obtained for each of these genes. The human loci for phosphate-activated glutaminase (GLS) and IL9 have previously been mapped to chromosomes 2 and 5, respectively, by analysis of somatic cell hybrid DNAs. By using chromosomal in situ hybridization, we have regionally mapped GLS to 2q32----q34 and IL9 to 5q31----q35.

Isolation of a human brain cDNA for glutamate dehydrogenase

A cDNA has been isolated from a human brain expression library using anti-bovine glutamate dehydrogenase (GDH) antibodies. The cDNA has an open reading frame of 774 nucleotides, which codes for 258 amino acids. The 258-amino-acid sequence is 95% homologous to the carboxy terminus of human liver GDH. This high degree of homology indicates that the cDNA codes for brain GDH. Fourteen differences between the amino acid sequence deduced from this cDNA and the sequence reported for human liver GDH suggest that there may be two active human GDH genes. A cRNA probe synthesized from the cDNA detects a 3.7-kilobase (kb) mRNA from human brain. Rat liver and kidney each contain two GDH mRNAs, 3.5 and 2.8 kb, respectively. The 3.5-kb transcript is prominent in rat brain, whereas the 2.8-kb transcript is barely detectable, a result suggesting that GDH gene expression is differentially controlled in rat brain.

Developmental induction of glutaminase in primary cultures of cerebellar granule cells

Glutaminase mRNA levels increased over 3-fold relative to total RNA, poly(A)+ RNA, and beta-actin mRNA in neonatal rat cerebellar granule cells as the cells differentiated between days 3 and 8 in culture. In contrast, mRNA levels of another glutamate cycle enzyme, glutamine synthetase, remained constant. Glutaminase protein levels increased per cell more than 2-fold between days 3 and 8, and at least 3-fold by day 10 in these cells. The total amount of glutamate per cell increased about 40% during this period. Glutaminase induction paralleled the development of Ca2+-dependent glutamate release, and the formation of neurites, synaptic vesicles, and synapses. The induction of glutaminase in developing granule cells is consistent with a special role for glutaminase in the synthesis of neurotransmitter glutamate.

Changes in glutamate-cycle enzyme mRNA levels in a rat model of hepatic encephalopathy

To detect possible changes in the regulation of glutamate/gamma-aminobutyric acid (GABA) enzymes at the level of gene expression in a thioacetamide-induced rat model of acute hepatic encephalopathy, we have examined changes in the mRNAs of four glutamate/GABA enzymes by quantitative RNA blot hybridization analysis. Such changes could reflect cell adaptation to excess ammonia or some other associated metabolic stress. The mRNA levels of glutamate dehydrogenase (GDH) decreased similarly in three different brain regions, whereas those of glutamine synthetase (GS) and glutaminase (GA) increased. The mRNA levels of glutamate decarboxylase (GAD) were unchanged. The results indicate that some effect of liver damage, presumably hyperammonemia, affected the expression of some, but not all, genes associated with ammonia and glutamate metabolism in the brain. This adaptation of gene expression to secondary effects of ammonia on brain amino acid neurotransmitter metabolism or brain energy metabolism could play a role in the physiological changes observed in hepatic encephalopathy.

Haplotypic diversity in human CEACAM genes: effects on susceptibility to meningococcal disease

Adhesion between the opacity-associated adhesin (Opa) proteins of Neisseria meningitidis and human carcino-embryonic antigen cell adhesion molecule (CEACAM) proteins is an important stage in the pathogenesis of meningococcal disease, a globally important bacterial infection. Most disease is caused by a small number of meningococcal genotypes known as hyperinvasive lineages. As these are also carried asymptomatically, acquisition of them alone cannot explain why only some hosts develop meningococcal disease. Our aim was to determine whether genetic diversity in CEACAM is associated with susceptibility to meningococcal disease. Frequency distributions of alleles, genotypes and haplotypes were compared in four CEACAM genes in 384 case samples and 190 controls. Linkage disequilibrium among polymorphic sites, haplotype structures and relationships were also analysed. A number of polymorphisms were observed in CEACAM genes but the diversity of CEACAM1, to which most Opa proteins bind, was lower, and a small number of high-frequency haplotypes were detected. Dose-dependent associations of three CEACAM haplotypes with meningococcal disease were observed, with the effect of carrying these haplotypes amplified in homozygous individuals. Two haplotypes were protective while one haplotype in CEACAM6 was associated with a twofold increase in disease susceptibility. These data imply that human CEACAM may be one determinant of human susceptibility to meningococcal disease.

Glutamic acid decarboxylase mRNA in rat brain: regional distribution and effects of intrastriatal kainic acid

Glutamic acid decarboxylase (GAD) mRNA was quantified in different regions of rat brain using an antisense RNA probe (ribo-probe) prepared from a cloned feline cDNA. In all brain regions studied a single band of GAD mRNA of approximately 3.7 kb was detected. The level of GAD mRNA was highest in the cerebellum, followed by the hypothalamus greater than thalamus greater than striatum greater than hippocampus greater than frontal cortex = parietal cortex greater than or equal to medulla = pons. Since GAD has been previously localized to intrinsic neurons of the striatum, we examined the effects of intrastriatal kainic acid administration on striatal GAD mRNA. The level of GAD mRNA in the kainic acid-lesioned striatum was reduced by 70-75% when compared to the contralateral (unlesioned) striatum. In contrast, the level of glutamine synthetase (an enzyme localized to glia) mRNA was increased approximately 290% in the kainic acid-lesioned striatum. There were no significant differences in GAD mRNA levels between the ipsilateral and contralateral cerebral cortices and hippocampi of rats injected with intrastriatal kainic acid.

Dexamethasone regulates glutamine synthetase expression in rat skeletal muscles

The regulation of glutamine synthetase expression by dexamethasone was studied in rat skeletal muscles. Daily administration of dexamethasone caused striking enhancement of glutamine synthetase activity in plantaris, soleus, and diaphragm muscles. Northern blot analysis revealed that the dexamethasone-mediated increase of glutamine synthetase activity was associated with dramatically increased levels of glutamine synthetase mRNA. Both glutamine synthetase activity and mRNA levels were significantly elevated in plantaris muscle at 0.5 mg.kg-1.day-1 of dexamethasone, a dose that approximates endogenous corticosteroid levels in animals under severe stress. Quantification of changes in glutamine synthetase mRNA on the basis of total mRNA (by oligo dT hybridization) also revealed a major increase in glutamine synthetase mRNA. Dexamethasone was without effect on beta-tubulin mRNA levels, indicating that glutamine synthetase induction is not part of a global response to glucocorticoids. Dexamethasone treatment resulted in only an approximately 15% increase in glutamine synthetase activity in heart; there was no change in glutamine synthetase mRNA level in this tissue. Thus glucocorticoids regulate glutamine synthetase gene expression in rat skeletal muscles.

Comparison of human brain and liver glutamate dehydrogenase cDNAS

In order to investigate suggestions that more than one glutamate dehydrogenase (GDH) gene may be active in humans, seven human brain and seventeen human liver GDH cDNAs were isolated by probing with a 590 base cDNA from the coding region of human brain GDH. No sequence heterogeneity was revealed among any of the cDNAs by an oligonucleotide binding assay, nor did any cDNA appear to encode a hexapeptide contained in a published amino acid sequence of human liver GDH. Homologous regions of three liver and three brain cDNAs had identical sequences over more than 2 kb, including 3' nontranslated regions. This suggests that identical GDH mRNAs are present in human brain and human liver. Although only one gene appears to be expressed, human genomic DNA blots show a pattern of hybridization consistent with the existence of more than one GDH gene.

Effect of altered acid-base balance and of various agonists on levels of renal glutamate dehydrogenase mRNA

Rat kidney contains 3.5-kb and 2.8-kb mRNAs that encode for glutamate dehydrogenase (GDH). The levels of both mRNAs are increased gradually after onset of chronic metabolic acidosis and reach a maximum induction of 2.5-fold after 7 days. In contrast, during recovery from chronic acidosis, the levels of the GDH mRNAs are returned to normal within 1 day. The development of an acute metabolic acidosis causes a more rapid induction of GDH mRNA. This increase occurs after a 7-h lag and plateaus after 18 h at a level that is threefold greater than normal. A very similar profile was observed after the transfer of LLC-PK-F+ cells from normal medium to an acidic medium containing 10 mM bicarbonate and adjusted to pH 6.9. However, the transfer of cells from acidic to normal medium caused an immediate and rapid [half-life (t) = 1 h] decrease in GDH mRNA. The apparent half-lives of GDH mRNA were measured by treating cells grown in normal (t = 4 h) and acidic media (t = 12 h) with actinomycin D. Thus, increased stability may account for the induction of GDH mRNA that occurs during growth in response to acidosis. The levels of GDH mRNA are independently affected by changes in medium pH or bicarbonate concentration. The levels of GDH mRNA are also increased by treating cells with adenosine 3',5'-cyclic monophosphate, epinephrine, triiodothyronine, or retinoic acid, whereas treatment with angiotensin II, vasopressin, phorbol 12-myristate 13-acetate, or cycloheximide did not produce an increase. The inductive effect of dexamethasone, which is observed in vivo, is not reproduced in the LLC-PK-F+ cells.

Effect of diabetes on glutamine synthetase expression in rat skeletal muscles

The regulation of glutamine synthetase expression in muscles from normal and diabetic (streptozotocin-treated) rats was studied. Muscle and body weights were markedly reduced in diabetic animals. Glutamine synthetase activity was significantly (2-fold) elevated 7 days after induction of diabetes. Increased enzyme activity persisted for at least 14 days after induction of diabetes, and it was apparent in both slow (soleus) and fast (plantaris) muscles. The diabetes-induced increase in enzyme activity was reflected in an increased steady-state level of glutamine synthetase mRNA. The increases in glutamine synthetase activity and mRNA level in muscle from diabetic rats were reversed by insulin administration. Increased expression of glutamine synthetase may be important for accelerated glutamine production by muscle from diabetic rats.

Multiple system degeneration with glutamate dehydrogenase deficiency: pathology and biochemistry

The neuropathological findings in a patient with antemortem diagnosis of olivopontocerebellar atrophy (OPCA) and reduced leucocytic glutamate dehydrogenase (GDH) activity included cerebellar cortical degeneration, most marked in the superior vermis, mild atrophy of the pons and the inferior olivary nucleus, marked reduction of anterior horn cells at all levels and gliosis in both lateral columns. GDH activities and their thermolability in "soluble" and "particulate" fractions in the cerebral cortex, cerebellar hemisphere and vermis were not significantly different from the values in two control brains. GDH mRNA in the patient's brain was not altered in size or amount.

Normal cerebellar glutamate dehydrogenase protein in spinocerebellar degeneration

Immunochemical analyses (Western blots) of cerebellar homogenates for glutamate dehydrogenase (GDH) from patients with spinocerebellar degeneration and control subjects were conducted. Four patients with autosomal dominant Joseph disease type of spinocerebellar degeneration, one patient with autosomal dominant olivopontocerebellar degeneration and four control subjects were studied. GDH was of the same molecular weight and amount in all patients and control subjects. These data together with normal GDH activity from these same homogenates published previously support the view that GDH is not involved in the pathogenesis of these types of dominantly inherited spinocerebellar degeneration.