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Biomedical subjects

S A Whatley

Publications and source records attributed to S A Whatley.

At least 19 recordsLinked to original sources
PubMed1995

Genetic linkage analysis of schizophrenia using chromosome 11q13-24 markers in Israeli pedigrees.

It is generally agreed that there is a genetic component in the etiology of schizophrenia which may be tested by the application of linkage analysis to multiply-affected families. One genetic region of interest is the long arm of chromosome 11 because of previously reported associations of genetic variation in this region with schizophrenia, and because of the fact that it contains the locus for the dopamine D2 receptor gene. In this study we have examined the segregation of schizophrenia with microsatellite dinucleotide repeat DNA markers along chromosome 11q in 5 Israeli families multiply-affected for schizophrenia. The hypothesis of linkage under genetic homogeneity of causation was tested under a number of genetic models. Linkage analysis provided no evidence for significant causal mutations within the region bounded by INT and D11S420 on chromosome 11q. It is still possible, however, that a gene of major effect exists in this region, either with low penetrance or with heterogeneity.

Chromosome Mapping↗
PubMed1992

Prion protein immunocytochemistry helps to establish the true incidence of prion diseases.

Creutzfeldt-Jakob disease (CJD) and Gerstmann-Strüssler-Scheinker disease (GSSD) are transmissible spongiform encephalopathies or prion diseases affecting man. It has been reported that prion diseases may occur without the histological hallmarks of spongiform encephalopathies: vacuolation of the cerebral grey matter, neuronal loss and astrocytosis. These cases without characteristic neuropathology may go undiagnosed and consequently the true incidence of transmissible dementias is likely to have been under-estimated. Immunocytochemistry using antibodies to prion protein gives positive staining of these cases, albeit the pattern of immunostaining differs from that seen in typical forms. Accumulation of prion protein is a molecular hallmark of prion diseases, and thus a reproducible, speedy and cost-efficient immunocytochemical screening of unusual dementias may help to establish the true incidence of prion diseases.

Adult↗
PubMed1992

Analysis of relative mRNA levels and protein patterns in brains of rat strains bred for differing levels of emotionality.

mRNA and protein populations were studied in the brains of Maudsley reactive (MR) and Maudsley nonreactive (MNR) rat strains, which exhibit differing levels of emotionality. Translational analysis of forebrain mRNA indicated that the relative levels of two translation products (42 kDA, pI 5.0; 30 kDa, pI 5.8) were increased in the MR compared to the MNR strain. In addition, a charge-shift variant of a 36 kDa protein was present in the MR strain. Analysis of brain protein patterns indicated that a protein of 39 kDa, pI 5.0, was found to be more abundant in MR compared with MNR strains in both frontal cortex and hippocampus and the relative level of one protein (40 kDa, pI 5.8) was decreased in the frontal cortex.

Animals↗
PubMed1992

Changes in relative levels of specific brain mRNA species associated with schizophrenia and depression.

Total cellular polyadenylated RNA (poly(A)+ RNA, mRNA) was prepared after guanidinium thiocyanate extraction of frozen brain tissue from age-matched controls and patients suffering from schizophrenia and unipolar depression. These mRNA populations were analysed by in vitro translation followed by two-dimensional gel analysis. Data were obtained from fluorograms derived from 10 different schizophrenic patients, 10 different controls and 5 different depressive patients. The relative concentrations of mRNA species coding for 4 translation products (33 kDa, pI 5.8; 26 kDa, pI 5.8; 35 kDa, pI 7.1; 23 kDa, pI 6.1) were significantly reduced in schizophrenia compared to controls when determined by computerised image analysis of the fluorograms. In the case of depression, the relative concentrations of mRNA species coding for 6 translation products were significantly altered, 4 being increased (38 kDa, pI 6.2, 17 kDa, pI 5.7, 35 kDa, pI 7.1; 23 kDa, pI 6.1) and two decreased (34 kDa, pI 6.2; 33 kDa, pI 5.8). Three translation products were altered in both schizophrenia and depression, one (33 kDa, pI 5.8) being altered according to the same trend, a decrease relative to controls, but two (35 kDa, pI 7.1; 23 kDa, pI 6.1) being altered differently in schizophrenia (reduced) and depression (increased). The effects of post mortem delay, mode of death and drug treatment on mRNA composition were also examined and found not to affect the levels of these translation products significantly. The significance of these changes will be discussed in relation to their relevance of biological mechanisms in the psychoses.

Aged↗
PubMed1992

Changes in brain gene expression in schizophrenic and depressed patients.

Poly(A+) mRNA was extracted from the post-mortem brain of schizophrenics (9 subjects), unipolar depressives (5 subjects) and controls (10 subjects) and used to direct the in vitro translation of radiolabelled protein in a cell-free reticulocyte-lysate system. Protein species were analysed on two-dimensional gels. Over 200 products were detected and, from these, 74 well-resolved species were chosen for further analysis. The optical density of each product was quantified by image analysis and normalised with respect to overall gel intensity. It was found that 7 novel, uncharacterised protein species, ranging from molecular weights (Mr) 17 kDa to 38 kDa and apparent isoelectric points (pI) 5.7-7.1, changed significantly in intensity in the psychotic groups compared to controls. One species changed only in the schizophrenia group (Mr = 26 kDa, pI = 5.8, 18% of control intensity) and 3 changed only in the depressive group (Mr = 38 kDa, pI = 6.2, 540% of control; Mr = 34 kDa, pI = 6.2, 6% of control; Mr = 17 kDa, pI = 5.7, 238% of control). Three further protein species were common to both psychotic groups (one species decreased in both schizophrenia and depression, Mr = 33 kDa, pI = 5.8; two species showed opposing intensity changes, decreasing in schizophrenia and increasing in depression, Mr = 35 kDa, pI = 7.1; Mr = 23 kDa, pI = 6.1). None of these changes was a function of post-mortem delay or mode of death. It is quite likely that such protein species reflect the abundance of specific mRNAs and target gene systems associated with the disease state.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

A specific effect of antipsychotic drugs on protein synthesis in human lymphomononuclear cells.

We have studied the effects of psychotropic drugs on patterns of protein synthesis in human lymphomononuclear cells by two-dimensional gel electrophoretic analysis. Drugs effective in treatment of schizophrenia specifically increased the relative synthesis of a 30-kDa polypeptide in cultured human lymphomononuclear cells whereas dopamine (DA) or psychoactive drugs lacking antipsychotic properties did not. The effect was stereospecific with respect to the clinically active and inactive isomers of flupenthixol. Synthesis of the 30-kDa polypeptide appears therefore to be correlated with antipsychotic properties but not with DA receptor binding. It is possible that such effects may be associated with the clinically beneficial effect of antipsychotic drugs in the brain.

Antipsychotic Agents↗
PubMed1988

Characterisation of messenger RNA extracted post-mortem from the brains of schizophrenic, depressed and control subjects.

Messenger RNA, obtained from post-mortem brain of 10 schizophrenics, five depressed patients and 10 control subjects, was characterised with respect to a number of parameters. It was found that post-mortem delay was not the major factor in determining RNA yield, size (as determined by cDNA synthesis) and biological activity. Biological activity, as determined by in vitro translation in a reticulocyte-lysate system, could be observed using messenger RNA from periods of 0 to 84 hours post-mortem. Two-dimensional gel analysis of the newly-synthesised radiolabelled products obtained from this material revealed several hundred individual species but no consistent degradation of any particular species with post-mortem delay. It is suggested, therefore, that premortem changes are as important as post-mortem changes in determining RNA yield, size and biological activity. Although no consistent difference could be found between patients and controls using any of these parameters, this study confirms that, by isolating messenger RNA from post-mortem human brain, valuable information can be gained on gene expression in psychiatric disorders.

Brain↗
PubMed1986

The brain 68-kilodalton microtubule-associated protein is a cognate form of the 70-kilodalton mammalian heat-shock protein and is present as a specific isoform in synaptosomal membranes.

The relationship between the 68-kilodalton microtubule-associated protein (68KMAP) and the major heat-induced protein (HSP70) in rat and human cells was investigated by comparison of their heat induction properties and by tryptic and Cleveland peptide mapping procedures. HSP70 synthesis was induced by heat shock of rat and human cells, whereas 68KMAP was a major synthesised protein in the absence of heat shock, with its synthesis being only slightly increased on heat shock. Tryptic peptide mapping, however, indicated strong peptide homology between the two proteins. These data, therefore, confirm that 68KMAP represents a constitutively expressed, heat-shock cognate gene. Two-dimensional gel electrophoretic analysis of subcellular fractions of rat brain, combined with peptide mapping procedures, indicated that 68KMAP exists as at least two isoforms separable by isofocussing, the more acidic of which (alpha 68KMAP) is present in fractions enriched in microtubules, cytosol, microsomes, synaptosomal plasma membranes, and synaptic vesicles, and the more basic of which (beta 68KMAP) is present predominantly in fractions enriched in synaptic vesicles and synaptosomal plasma membranes. These two forms are distinguishable in terms of changes in Cleveland peptide maps, and we conclude that alpha- and beta 68KMAP, therefore, represent distinct forms. The significance of these findings to the molecular pathogenesis of Down's syndrome in the human brain is discussed.

Animals↗
PubMed1984

The brain isoform of a key ATP-regulating enzyme, creatine kinase, is a phosphoprotein.

Two-dimensional electrophoretic analysis of crude microtubule preparations from the rat brain revealed the presence of three polypeptides in positions corresponding to those of the isovariants of purified rat brain creatine kinase (CK-BB). By the use of [gamma-32P]ATP, the two more acidic forms of these polypeptides were shown to be phosphorylated. Their identity as phosphorylated forms of CK-BB was established by using various peptide mapping techniques. Thus CK-BB is a phosphoprotein and its isoelectric variation may be attributed to phosphorylation.

Adenosine Triphosphate↗
PubMed1984

Alterations in the relative amounts of specific mRNA species in the developing human brain in Down's syndrome.

Total cellular polyadenylated RNA [poly(A)+ RNA] was prepared after guanidinium thiocyanate extraction of frozen brain tissue from age-matched normal and Down's-syndrome (trisomy 21) human foetuses. Poly(A)+ RNA populations were analysed by translation in vitro, followed by two-dimensional gel analysis by using both isoelectric focusing (ISODALT system) and non-equilibrium pH-gradient electrophoresis (BASODALT system) as the first-dimension separation. The relative concentrations of poly(A)+ RNA species coding for seven translation products were significantly altered in Down's syndrome, as determined by both visual comparisons of translation-product fluorograms from normal and Down's-syndrome samples and by quantitative radioactivity determination of individual translation products. The relative concentrations of mRNA species coding for two proteins (68 kDa and 49 kDa) were increased in Down's syndrome and may represent genes located on chromosome 21. The relative concentrations of mRNA species coding for five proteins (37 kDa, 35 kDa, 25.5 kDa, 24.5 kDa, 23 kDa) were decreased in Down's syndrome, these probably representing secondary effects of the trisomy. Six Down's-syndrome-linked translation products (49 kDa, 37 kDa, 33 kDa, 25.5 kDa, 24.5 kDa, 23 kDa) did not migrate with appreciable amounts of cellular proteins on two-dimensional gels and hence may represent either proteins of high turnover rates or those that are post-translationally modified in vivo. One translation product (68 kDa) comigrated with a major cellular protein species, which was identified as a 68 kDa microtubule-associated protein by limited peptide mapping. The significance of these changes is discussed in relation to the mechanisms whereby the Down's-syndrome phenotype is expressed in the human brain.

Brain↗
PubMed1983

In vitro neurotoxic assessment of antitumour drugs.

We have developed a rapid, specific, in vitro method for quantitatively assessing neurotoxicity of antitumour drugs and related compounds. Using cultures of foetal rat hypothalamic neurones and a staining procedure which specifically identifies neuronal cells, the neurotoxicity of 8 antitumour drugs has been evaluated. The order of neurotoxicity appears to correlate well with their known relative clinical toxicities. Neurotoxicity of the radiosensitizer misonidazole was also identified using this system. This method appears to provide a valuable preclinical screen for neurotoxicity which may be particularly useful in the development of new antitumour drug analogues and radiosensitizers.

Animals↗
PubMed1982

The polyadenylated RNA directing the synthesis of the rat myelin basic proteins is present in both free and membrane-bound forebrain polyribosomes.

Free and membrane-bound polyribosomes were isolated from the forebrain of actively myelinating 24-day-old rats. The poly(A)+ RNA (polyadenylated RNA) extracted from both fractions was translated in vitro in reticulocyte lysates [Hall & Lim (1981) Biochem. J. 196. 327-336] in the presence or absence of a heterologous microsomal membrane fraction from dog pancreas. The rat myelin basic proteins synthesized in vitro were isolated by CM-cellulose chromatography and by immunoprecipitation with purified anti-(myelin basic protein) antibody. The large (mol.wt. 18 500) and small (mol.wt. 16 000) myelin basic proteins were translational products of poly(A)+ RNA from both free and membrane-bound polyribosomes. The identity of the myelin basic proteins was verified by analysis of peptides generated by the cathepsin D digestion of the immunoprecipitated proteins synthesized in vitro, in comparison with authentic rat myelin basic proteins. Although several other translational products of membrane-bound polyribosomal poly(A)+ RNA were modified when microsomal membranes were present during translation, molecular weights of the myelin basic proteins themselves were unchanged. The myelin basic proteins synthesized in vitro also did not differ significantly in size from the authentic myelin basic proteins, indicating that these membrane proteins are unlikely to be synthesized as substantially larger precursor molecules. The presence of the specific mRNA species on both free and membrane-bound polyribosomes is compatible with the extrinsic location of the myelin basic proteins on the cytoplasmic surface of the myelin membrane.

Animals↗
PubMed1982

Cytotoxic effects and biological activity of 2-aza-8-germanspiro[4,5]-decane-2-propanamine-8,8-diethyl-N,N-dimethyl dichloride (NSC 192965; spirogermanium) in vitro.

Lethal and other biological effects of 2-aza-8-germanspiro[4,5]decane-2-propanamine-8,8-diethyl-N,N-dimethyl dichloride (NSC 192965; spirogermanium), representing a new chemical class of compound exhibiting antitumor activity, have been studied in vitro. Survival curves for NIL 8 hamster cells were exponential with greater kill occurring with increasing drug concentrations and longer exposure times. Cytotoxicity was temperature dependent. "Quiescent" cultures were significantly less sensitive to spirogermanium than were logarithmically growing cells. These lethal effects showed no phase specificity. There was no evidence of progression delay through the cycle following spirogermanium treatment. When spirogermanium was tested against a range of human cell lines, the consistency of the values for the drug concentration required to reduce survival by 50% on the exponential part of the survival curve, derived from colony-forming assays, was most marked. The survival curves, characterized by an initial shoulder, were steep and exponential with measurements possible over only a narrow concentration range since complete cell lysis occurred at levels causing a greater than 2-log kill. Cell membrane damage by spirogermanium, as judged by dye exclusion, was progressive with time and increasing drug concentrations. Protein synthesis proved most susceptible to the drug. Spirogermanium concentrations cytotoxic to tumor cells were also toxic to cultured rat neurons, confirming the clinical neurological toxicity encountered. The precise mode of action of spirogermanium remains to be established, and these data further illustrate its apparent lack of specificity.

Animals↗
PubMed1981

Chromatin organization in the rat hypothalamus during early development.

The organization of chromatin in neuronal and glial nuclei isolated from different brain regions of rats during development was studied by digestion of nuclei with micrococcal nuclease. A short chromatin repeat length (approx. 176 base-pairs compared with that of glial nuclei from foetal cerebral cortex (approx. 200 base-pairs) was present in hypothalamic neurons throughout the ages studied, which was similar to the repeat length of cortical neurons from 7- and 25-day-old animals (approx. 174 base-pairs). Whereas in cortical neurons the chromatin repeat length shortened from approx. 200 base-pairs in the foetus to approx. 174 base-pairs in the first postnatal week, the short chromatin repeat length of hypothalamic neurons was already present 2 days before birth, indicating that hypothalamic neurons differentiate earlier than cortical neurons during brain development.

Animals↗