Expression of the Huntington's disease (IT15) protein product in HD patients

Huntington's disease (HD) is an inherited, neurodegenerative disorder caused by expansion of a CAG repeat in the IT15 gene, leading to an expanded glutamine repeat in the HD protein. The mechanism by which the expanded repeat causes expression of the disease is not known, though there do not appear to be changes in the mRNA levels. We have conducted quantitative Western blot analyses of HD patients and controls. Expression of the IT15 protein is essentially equal in control and HD frontal cortex. In caudate from HD patients, IT15 protein is decreased in parallel with the decrease in a neuronal marker, suggesting that loss of IT15 protein is secondary to neuronal loss. In order to determine expression of the two alleles of the IT15 protein we used Western blots of 4% polyacrylamide gels. Both alleles of the IT15 protein were expressed at similar levels in HD lymphoblastoid cell lines and HD post-mortem hippocampus and cerebellum (regions relatively spared in HD), indicating that even very long CAG repeats can be translated into polyglutamine. In contrast, in cerebral cortex and caudate (regions severely affected in HD), in the longer expanded repeat cases the expanded allele of the IT15 protein was present at a significantly lower level (compared with the normal length allele), often with a smear of more slowly migrating reactivity above it. These data suggest the possibility of altered structure, abnormal processing or abnormality of protein-protein interactions involving the IT15 protein with the expanded glutamine repeat.

Characterization of cDNA clones containing CCA trinucleotide repeats derived from human brain

Expansion mutation is the cause of eight neuropsychiatric disorders. Thus far each disease is the result of expansion of a C-G rich trinucleotide repeat that is polymorphic for length in the general population. We now report the identification of seven novel cDNA clones with CCA or equivalent trinucleotide repeats obtained by screening a human frontal cortex cDNA library. The repeat lengths of two clones, CCA11 (linked to D20S101, expressed in human brain as a 3.2 kb message) and CCA38 (linked to D5S404), are highly polymorphic in a normal human population. CCA54, mapped to chromosome 19, appears to correspond to a portion of the human gene encoding the alpha 1 subunit of a P-type calcium channel. Expansion mutations at these loci should be considered as possible candidates in evaluating the genetic etiologies of diseases linked to chromosomes 5, 19, and 20.

Microsatellite evolution--evidence for directionality and variation in rate between species

Microsatellite DNA sequences are rapidly becoming the dominant source of nuclear genetic markers for a wide range of applications, from genome mapping to forensic testing to population studies. If misinterpretation is to be avoided, it is vital that we understand fully the way in which microsatellite sequences evolve. We have therefore compared allele length distributions for 42 microsatellites in humans with their homologues in a range of related primates. We find a highly significant trend for the loci to be longer in humans, showing that microsatellites can evolve directionally and at different rates in closely related species.

Assessment of dissociative identity disorder with the Million Clinical Multiaxial Inventory-II

96 patients with a clinical diagnosis of Dissociative Identity Disorder were administered the Million Clinical Multiaxial Inventory-II. The most elevated personality disorder scales were Avoidant, Self-defeating, Borderline, and Passive-Aggressive personality disorders. Elevated Axis I scales included Dysthymia, Major Depression, Thought Disorder, and Anxiety Disorder. Million-II profiles of a patient before and after integration showed normalization of a previously pathological profile.

In vivo D2 dopamine receptor density in psychotic and nonpsychotic patients with bipolar disorder

BACKGROUND

A prior positron emission tomographic study from The Johns Hopkins University, Baltimore, Md, using N-methylspiperone labeled with carbon 11 reported elevated basal ganglia D2 dopamine receptor density (Bmax) values in neuroleptic-naive schizophrenic patients compared with controls. We have now extended these studies to include patients with bipolar disorder.

METHODS

Patients with bipolar disorder (n = 14) either had never received neuroleptic medication or had been neuroleptic-free for more than 6 months, and they met DSM-III criteria for currently symptomatic affective disorder. Patients with bipolar disorder were compared with matched schizophrenic patients and normal controls. All received two positron emission tomographic scans, the second of which was preceded by oral administration of haloperidol lactate, to permit the calculation of D2 dopamine receptor Bmax.

RESULTS

Diagnostic groups differed in Bmax by analysis of variance (P < .0001); post hoc tests showed higher Bmax values for psychotic patients with bipolar disorder and schizophrenic patients compared with normal controls and for schizophrenic patients and psychotic patients with bipolar disorder compared with nonpsychotic patients with bipolar disorder. Among patients with bipolar disorder, Bmax values correlated significantly with the severity of psychotic symptoms (r = .63) on the Present State Examination but not with the severity of nonpsychotic mood symptoms.

CONCLUSIONS

We conclude that, like schizophrenic patients, patients with psychotic bipolar disorder have elevations of D2 dopamine receptor Bmax values and that such elevations in affective disorder are more closely associated with the presence of psychosis than with mood abnormality. Elevations in dopamine receptor values thus may occur in psychiatric states that are characterized by psychotic symptoms rather than being specific to schizophrenia.

Trypanosoma evansi: measurement of pyruvate production as an indicator of the drug sensitivity of isolates in vitro

In a previous study, three in vitro methods for the assessment of drug sensitivity among Trypanosoma evansi isolates were compared--a direct counting method, pyruvate production method and uptake of radiolabelled hypoxanthine. The pyruvate assay system, which measures the amount of pyruvate in the supernatant of growing populations of trypanosomes by a spectrophotometric method, was selected for further investigation with regard to its suitability for field studies. The effect of initial seeding density and incubation time on the growth of three stocks of T. evansi--TREU 1840 and TREU 1981 (suramin sensitive) and TREU 2136 (suramin resistant)--and drug sensitivities revealed by the pyruvate assay and direct counting were examined to optimise assay conditions. Maximum densities and pyruvate production achieved were not affected by varying the initial seeding densities in the range of 5 x 10(4)-5 x 10(5)/ml and had been reached after 48 hours incubation with one exception: Pyruvate levels continued to increase up to 72 hours in the suramin resistant stock. However, inhibition curves were affected by initial seeding density and incubation period. Results suggested that an initial seeding density of 1 x 10(5)/ml and an incubation time of 48 hours are optimal for the assay. Using these assay conditions, the isolates were screened against suramin, quinapyramine sulphate and Cymelarsan, the trypanocides used most commonly against T. evansi. This assay proved to be a relatively simple and cheap technique applicable to screening large numbers of isolates of differing sensitivities to trypanocidal drugs.

Cloning and expression of the rat atrophin-I (DRPLA disease gene) homologue

Dentatorubral pallidoluysian atrophy (DRPLA) is a rare, progressive, fatal neuropsychiatric disorder similar to Huntington's disease, caused by an expansion of a CAG trinucleotide repeat encoding glutamine. We have cloned the cDNA of the rat homologue of this gene. The cDNA contains a 3549 base pair open reading frame that is 88.2% identical to the human cDNA, with a predicted amino acid sequence that is 93.6% identical to the human sequence. The consecutive glutamine repeat is only five residues in length (normal range in human: 7-35 glutamines) and is followed by a polymorphic region of alternating glutamine and proline residues (QQQQQPQPQPQPQQ). The sequence also includes a polymorphic proline repeat, a serine repeat, and a region of alternating acidic and basic residues. Northern analysis and in situ hybridization indicate that the gene is widely expressed as a 4.5 kb mRNA, with a neuronal distribution in the brain. The widespread expression of this gene is consistent with the possibility that DRPLA, like other glutamine repeat diseases, is a result of an abnormality at the protein level.

Positive and negative symptoms in dissociative identity disorder and schizophrenia: a comparative analysis

A substantial number of patients with dissociative identity disorder have had previous diagnoses of schizophrenia, due to the presence of positive symptoms of schizophrenia. The authors investigated the pattern of positive and negative symptoms in patients with dissociative identity disorder, and compared it with norms in schizophrenia. A total of 108 patients with a clinical diagnosis of dissociative identity disorder were administered the Positive and Negative Syndrome Scale. The positive symptom and general psychopathology scores were significantly more severe in the dissociative identity group than the norms for schizophrenia, while the negative symptoms were significantly more severe in schizophrenia. Since patients with dissociative identity disorder report more positive symptoms of schizophrenia than do schizophrenics, while schizophrenics report more negative symptoms, a primary emphasis on positive symptoms may result in false-positive diagnoses of schizophrenia and false-negative diagnoses of dissociative identity disorder.

Expression of the mutant allele of IT-15 (the HD gene) in striatum and cortex of Huntington's disease patients

Huntington's disease (HD) is an inherited neurodegenerative disorder expressed when a trinucleotide repeat in the gene IT-15 is expanded. The mechanism by which the expanded repeat causes the expression of the disease is unknown. Possible mechanisms include alterations in the amount of the mRNA, potentially resulting from changes in gene transcription or abnormal mRNA stability. In order to determine whether the expanded IT-15 allele is present in mRNA, we isolated total RNA from the cortex and striatum of patients and controls. To distinguish the two alleles of the IT-15 transcript in HD patients, we amplified across a region containing a dimorphic single triplet deletion observed on some chromosomes and found that the relative intensity of the two PCR bands amplified from genomic DNA and those amplified from first strand cDNA from brain tissue were essentially equal. In order to determine whether the exon containing the expanded CAG repeat is present in IT-15 mRNA from HD patients, we amplified across this region and demonstrated the presence of the expanded repeat in cDNA from both striatum and cortex. Based on this evidence, we suggest that the mechanism of disease expression does not occur during transcription or in the stability of the RNA, but rather occurs during translation or postranslationally.

Flagellum-mediated adhesion of Trypanosoma congolense to bovine aorta endothelial cells

We studied the interaction between Trypanosoma congolense and bovine aorta endothelial (BAE) cell monolayers. Our findings suggest that trypanosomes adhere predominantly to the flattened, peripheral cell surface domains as well as to filamentous endothelial outgrowths that are present during in vitro cultivation in non-confluent monolayers. Adhesion is mediated exclusively by the flagellum in a distinct geometrical order with respect to the flagellar cytoskeleton. Thus, it is possible to define exactly the trypanosomal cell surface domain involved in the attachment process. After 24-48 h of cultivation on monolayers, trypanosomes start to develop short, filopodia-like flagellar protrusions, which serve as additional elements in assisting parasite attachment. Small filaments (3-5 nm) also serve as cross-links between flagellar and endothelial cell surface membranes. Lectin-gold labeling shows that these cross-links contain sialic acid residues. In vitro assays confirm that sialic acid is involved in the adhesion process, whereas the extracellular matrix (ECM) proteins fibronectin, collagen, laminin and vitronectin are not. The presence of T. congolense exhibits a mitogenic effect on BAE cells.

The interaction of Trypanosoma congolense with endothelial cells

Factors which affect adhesion of cultured Trypanosoma congolense bloodstream forms to mammalian feeder cells have been examined. Using an in vitro binding assay, the initial events following interaction of trypanosomes with bovine aorta endothelial (BAE) cells were monitored by both light- and electron microscopy. Metabolic inhibitors and other biochemicals were incubated with either cells or parasites, to test whether any inhibited the process. Our findings suggest that adhesion of the parasites is an active process requiring metabolic energy from the trypanosomes, but not from endothelial cells. We also provide data suggesting that T. congolense bloodstream forms possess a lectin-like domain, localized at distinct sites on their flagellar surface, which interacts with specific carbohydrate receptors, most likely sialic acid residues, on the endothelial cell plasma membrane. We also suggest that the cytoskeletal protein actin is probably involved in this interaction.

RNA editing of the glutamate receptor subunits GluR2 and GluR6 in human brain tissue

Editing of mRNA in the coding region of the second transmembrane domain of glutamate receptor subunits GluR2, GluR5, and GluR6 involves a change of the base A in genomic DNA to the base G in mRNA as described in rat brain. To determine whether this reaction occurs in humans as well as rats, we studied RNA editing of GluR2 and GluR6 in human brain. We compared the extent of editing in controls and cases with Huntington's disease. To assay the extent of editing in brain RNA, first strand cDNA was amplified using the polymerase chain reaction yielding a product across the region of the second transmembrane spanning segment in which editing takes place in rats. The PCR product was incubated with the restriction enzyme BbvI, which recognizes the sequence GCAGC present in the nonedited sequence of the mRNA in subunits GluR2 and GluR6. Thus, BbvI cuts the nonedited version but leaves the edited version intact. As in the rat, the GluR2 subunit mRNA was completely edited in human brain. The GluR6 subunit was nearly completely edited in all gray matter structures investigated including cortex, striatum, thalamus, hippocampus, amygdala, and cerebellum with extent of editing ranging from 89% in the cerebellum to 95% in the cortex and striatum. No significant differences in the extent of RNA editing were apparent in control versus Huntington's disease brains. To compare the extent of editing in neurons and glia in the brain, editing in cerebral cortex (predominantly gray matter and thus neurons) was compared with editing in corpus callosum (white matter and thus nearly completely glial cells).(ABSTRACT TRUNCATED AT 250 WORDS)

Epithelial inositol 1,4,5-trisphosphate receptors. Multiplicity of localization, solubility, and isoforms

In an earlier subcellular fractionation study of epithelial tissue (liver and pancreas), we demonstrated that the inositol 1,4,5-trisphosphate receptor (IP3R) is found in association with biochemically distinct cellular membranes, including the endoplasmic reticulum (ER) and plasma membrane (Sharp, A. H., Snyder, S. H., and Nigam, S. K. (1992) J. Biol. Chem. 267, 7444-7449). To further characterize epithelial IP3Rs, we have now employed cultured Madin-Darby canine kidney (MDCK) cells, a well studied tight polarized epithelial cell type. Indirect immunofluorescence with an antiserum which specifically recognizes IP3R in MDCK cells by immunoblotting and immunoprecipitation gave an ER-like staining pattern as well as a basolateral plasma membrane-like staining pattern, the latter being particularly evident in highly confluent monolayers. In sections of adult rat kidney tubules a similar staining pattern was observed. Interestingly, whereas known basolateral proteins (Na+,K(+)-ATPase and the facilitated glucose transporter) gave a continuous basolateral staining pattern, that seen for IP3R was discontinuous (punctate). A highly similar staining pattern was observed for the caveolar protein, caveolin, suggesting that the punctate basolateral plasma membrane-like staining pattern observed for IP3R reflects its localization to basolateral caveolae. Biotinylation of non-permeabilized and permeabilized MDCK cells, followed by immunoprecipitation of IP3R and detection with streptavidin, indicated that while most IP3R is localized to biotin-inaccessible compartments (i.e. ER), a fraction (10-20%) of IP3R was accessible to externally added biotin primarily from the basolateral side. This result is compatible with the dual ER and basolateral caveolar localization suggested by immunocytochemistry, although it does not exclude the presence of some IP3R in the basolateral plasma membrane as well. Solubility studies revealed IP3R to be considerably more insoluble than the basolateral proteins, Na+,K(+)-ATPase and the liver cell adhesion molecule, as well as the cytoskeletal proteins, ankyrin and fodrin. In the most insoluble fraction, IP3R was found along with caveolin, further supporting the notion that part of the cellular IP3R pool associates with caveolae. Since multiple localizations of IP3R within a cell might reflect the existence of multiple isoforms, polymerase chain reaction amplification of first strand cDNA with primers specific for the three isotypes of IP3R was performed. All three isoforms of IP3R were expressed in the homogeneous population of MDCK cells. The existence of distinct membrane localizations and multiple isoforms of IP3R within the same cell type suggests an explanation for the complex spatiotemporal patterns of Ca2+ release from inositol 1,4,5-trisphosphate-sensitive Ca2+ pools in epithelial and other cells.

Glutaramyl-beta-alanyl spacer group for haptenic coupling to proteins. Preparation of immunogens for antibody production against polychlorinated biphenyls

By use of a glutaramyl-beta-alanyl spacer group, a hapten for the polychlorinated biphenyl, 2,2',4,4',5,5'-hexachlorobiphenyl (1), viz., 2-amino-2',4,4',5,5'-pentachlorobiphenyl (2), was successfully conjugated to carrier proteins to provide immunogens with high hapten/protein molar substitution ratios (MSR's). The procedure allows for the incorporation of beta-[3H]-alanine into the immunogen, thereby providing an accurate radiochemical method for the quantitative assessment of MSR. The use of the glutaramyl spacer group was prompted by the observation that the corresponding succinamyl group was subject to side reactions manifested by succinimide formation during the carboxyl activation step to an activated ester for subsequent coupling to proteins, thus severely compromising the coupling yields. The glutaramyl-beta-alanyl spacer group should be generally applicable for protein conjugation of any hapten with an amino functional group in the molecule.

Redistribution and enhanced urinary excretion of 2,2',4,4',5,5'-hexachlorobiphenyl (HCB) in rats using HCB-specific IgG and Fab fragments

Drug-specific antibody fragments can enhance the elimination of some drugs by redistributing drug from tissues into serum and allowing renal excretion of the drug-antibody complex. This approach could potentially be used to enhance the elimination of compounds such as polychlorinated biphenyls that have very long elimination half-lives. As a first step in testing this hypothesis, the effects of 2,2',4,4',5,5'-hexachlorobiphenyl (HCB)-specific antibodies and their corresponding Fab fragments on HCB disposition were studied in rats. Antibodies to HCB were produced in chickens, and the corresponding Fab fragments were produced by digestion with papain. To study antibody effects on HCB distribution, [14C]HCB (0.1 mg) was administered i.v. to rats. Two weeks later, after distribution to tissues was complete, anti-HCB IgG or control IgG was administered i.v. The serum radiolabel concentration 2 hr after IgG administration increased 185 +/- 64% in animals treated with specific antibody vs 51 +/- 19% in control animals (P < 0.001). The increase in serum radiolabel concentration was apparent within 30 min and maximal at 2 hr. To study effects on HCB excretion, anti-HCB or control Fab fragment was administered 2 weeks after [14C]HCB. Urinary HCB excretion over the next 24 hr, measured by gas chromatography, was 10-fold greater in the group treated with anti-HCB Fab (P < 0.01). These data demonstrate that anti-HCB IgG can redistribute HCB rapidly from tissues into serum and that anti-HCB Fab can enhance urinary HCB excretion. While the magnitude of these changes was small, the data suggest that increasing HCB excretion using drug-specific antibody fragments is feasible, and can serve as a model for enhancing the excretion of compounds that have very long elimination half-lives.

Localization of inositol trisphosphate receptor subtype 3 to insulin and somatostatin secretory granules and regulation of expression in islets and insulinoma cells

Calcium ions play a central role in stimulus-secretion coupling in pancreatic beta cells, and an elevation of cytosolic Ca2+ levels is necessary for insulin secretion. Inositol 1,4,5-trisphosphate mobilizes intracellular Ca2+ stores in the beta cell by binding to specific receptors that are ligand-activated Ca2+ channels. The inositol trisphosphate receptors comprise a family of structurally related proteins with distinct but overlapping tissue distributions. Previous studies indicated that the predominant inositol trisphosphate receptor subtype expressed in rat pancreatic islets was the protein designated IP3R-3. We have confirmed the expression of IP3R-3 in pancreatic islets by immunohistocytochemistry and localized this protein to the secretory granules of insulin-secreting beta cells and somatostatin-secreting delta cells by immunogold electron microscopy. Secretory granules contain high levels of Ca2+, and the presence of IP3R-3 in the granule provides a mechanism for mobilizing granule Ca2+ stores in response to glucose and/or hormones. The release of Ca2+ from granule stores would increase the Ca2+ concentration in the surrounding cytoplasm and promote rapid exocytosis of granules, especially those granules in close proximity to the plasma membrane. The levels of IP3R-3 were increased in pancreatic islets of diabetic rats and rats that had been refed after a period of fasting. They were also increased in rat insulinoma RINm5F cells cultured in 25 mM glucose compared with cells cultured in 5 mM glucose. The localization of IP3R-3 to secretory granules of insulin-secreting beta cells and somatostatin-secreting delta cells suggests that granule Ca2+ stores actively participate in the secretory process and that their release is regulated by inositol 1,4,5-trisphosphate. The regulation of IP3R-3 levels by glucose, diabetes, and refeeding may allow the beta cell to adjust the insulin secretory response to changing physiological conditions.

Triplet repeats in clinical subtypes of schizophrenia: variation at the DRPLA (B 37 CAG repeat) locus is not associated with periodic catatonia

Clinical evidence for a dominant mode of inheritance and anticipation in periodic catatonia, a distinct subtype of schizophrenia, indicates that genes with triplet repeat expansions or other unstable repetitive elements affecting gene expression may be involved in the etiology of this disorder. Because patients affected with dentatorubral-pallidoluysian atrophy (DRPLA) may present with "schizophrenic" symptoms, we have investigated the DRPLA (B 37 CAG repeat) locus on chromosome 12 in 41 patients with periodic catatonia. The B 37 CAG repeat locus was highly polymorphic but all alleles in both the patient and control group had repeat sizes within the normal range. We conclude that variation at the DRPLA locus is unlikely to be associated with periodic catatonia. The evidence for dominant inheritance and anticipation as well as the high prevalence of human brain genes containing trinucleotide repeats justifies further screening for triplet repeat expansions in periodic catatonia.

The Valsalva DCR bubble test: a new method of assessing lacrimal patency after DCR surgery

Objective confirmation of nasolacrimal patency following dacryocystorhinostomy is a desirable postoperative goal for both the surgeon and the patient. The authors describe a simple method to demonstrate dacryocystorhinostomy patency and present a study comparing the effectiveness of this novel test with Jones fluorescein testing in 32 cases seen consecutively at postoperative follow-up. The test consists of demonstrating reflux of air through the dacryocystorhinostomy as the patient performs the Valsalva maneuver. This reflux is most easily seen as bubbles rising through a drop of saline placed in the medial canthus. A high correlation was found between this test and Jones testing. The Valsalva dacryocystorhinostomy bubble test (VBT) appears to be a fast, safe, and accurate method of confirming dacryocystorhinostomy patency.

Selective loss of [3H]kainic acid and [3H]AMPA binding in layer VI of frontal cortex in Huntington's disease

Excitatory amino acid neurotoxicity has been proposed to cause the neostriatal neuronal degeneration of Huntington's disease (HD); N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA), and kainate receptors have been hypothesized to play important roles in this process. We have recently reported a loss of neurons in layer VI of the cerebral cortex in HD. Using quantitative autoradiographic methods, we have now measured NMDA, AMPA, and kainate receptor binding in the frontal cerebral cortex of the brains of controls and individuals with HD. We find no change in NMDA receptor binding but a selective decrease in kainate and AMPA receptor binding in layer VI. These data suggest that cerebral cortical neurons possessing kainate or AMPA receptors may be selectively vulnerable in individuals with HD.

Human GluR6 kainate receptor (GRIK2): molecular cloning, expression, polymorphism, and chromosomal assignment

Glutamate receptors mediate the majority of excitatory neurotransmission in the brain, and molecular cloning studies have revealed several distinct families. Because neuropathological states and possibly human disorders may involve kainate-preferring glutamate receptors, we have isolated a cDNA clone for the human GluR6 kainate-preferring receptor. This clone shows a very high sequence similarity with that of the rat, except for a part of the 3' untranslated region in which there is a TAA triplet repeat. When the protein was overexpressed in human embryonic kidney 293 cells, it had a molecular weight, an antibody recognition, and a glutamate ligand-binding profile similar to those of the rat GluR6 receptor. Northern analysis showed expression in both human cerebral and cerebellar cortices. By PCR analysis of rodent-human monochromosomal cell lines, the human GluR6 could be assigned to chromosome 6. The length of the TAA triplet repeat was polymorphic in the normal population, with at least four alleles and an observed heterozygosity of about 45%. These studies should provide the basis for expression or linkage studies of the GluR6 kainate receptor in human disease or neuropathologic states.

Reversal of desipramine toxicity in rats with polyclonal drug-specific antibody Fab fragments

Drug-specific antibodies, or fragments containing their binding site(s), are a potential means of treating drug overdose. Affinity purified polyclonal ovine Fab (TFab) with a high average affinity constant (Ka = 1.4 x 10(10) M-1) for the common tricyclic antidepressants was evaluated as a possible treatment for tricyclic antidepressant toxicity. Groups of eight anesthetized rats received 30 mg/kg body weight of desipramine (DMI) intraperitoneally, followed after 15 minutes by a 10-minute intravenous injection of 3 ml normal saline solution, 2 gm/kg nonspecific Fab as a control (CFab), or 1 or 2 gm/kg TFab (representing a molar ratio of TFab to DMI of 0.11 and 0.22, respectively). The animals were observed for 3 hours. During the initial 15 minutes, serum DMI levels in the four groups reached 2.3 to 2.9 micrograms/ml, the QRS duration increased by 67.5% to 77.9%, and the systolic pressure fell to between 65% and 85% of its initial value. The group given saline solution showed a gradual return of all these parameters toward normal, whereas CFab caused a transient further QRS prolongation. CFab also caused an initial rise in blood pressure, which then fell progressively, and two of the rats died 2 to 3 hours later with hypotension and bradycardia. Serum DMI concentration did not change significantly in either the saline or CFab groups.(ABSTRACT TRUNCATED AT 250 WORDS)

The inositol trisphosphate receptor gene family: implications for normal and abnormal brain function

1. The phosphatidyl inositol (PI) second messenger system has been extensively investigated in the past decade. This complex pathway results in the production of two second messengers, one of which, inositol 1,4,5-trisphosphate, will be the focus of this review. 2. The intracellular receptor for this second messenger (IP3R) has been purified, reconstituted and extensively characterized in both brain and peripheral tissues. 3. Localization and functional studies show that IP3 binding causes the receptor to release portions of the intracellular calcium stores. 4. Multiple modulators of the receptor have been identified, including pH, calcium concentration, adenine nucleotide concentration and phosphorylation. 5. The cDNA for this molecule has been cloned from a number of sources. Studies of the molecular structure of the receptor have revealed additional levels of complexity including multiple alternative splicing events in the initially cloned cerebellar (Type I) receptor, as well as the existence of highly related but distinct cDNAs which likely reflect a gene family. 6. There is suggestive evidence linking the PI system, and thus the IP3R, to bipolar disorder and the actions of lithium.

Heligmosomoides polygyrus and Trypanosoma congolense infections in mice: a laboratory model for concurrent gastrointestinal nematode and trypanosome infections

A murine model using Heligmosomoides polygyrus and Trypanosoma congolense has been developed for studying the effects of concurrent chronic gastrointestinal nematode and trypanosome infections. Female outbred mice were infected either with 500 infective larvae (L3) of H. polygyrus or with 10(4) bloodstream forms of T. congolense or both. In concurrent infections, animals were dosed with both parasites simultaneously or the trypanosomes were injected 5 or 10 days after the mice were infected with the nematode. The course of infection was monitored by routine parasitological and immunological techniques for 30 days after the H. polygyrus infection. Concurrently infected mice were severely compromised, except when T. congolense was superimposed on a 10-day-old (adult) H. polygyrus infection. In H. polygyrus-infected mice, simultaneous or subsequent infection with trypanosomes did not markedly influence worm establishment or fecundity, but the female worms were slightly stunted. Surviving mice displayed a markedly reduced antibody response to H. polygyrus antigens and a slightly reduced antibody response to T. congolense antigens.

Trypanocidal activity of a myristic acid analog in axenic cultures of Trypanosoma evansi

The growth of bloodstream forms of Trypanosoma evansi in axenic culture was inhibited by incubation with 11-oxatetradecanoic acid (O-11), an analog of myristic acid. Parasites isolated from Asia, Africa and South America were affected to a similar extent in measurements using three different assay systems concerned with different aspects of trypanosome growth and metabolism. The concentration of O-11 that inhibited trypanosome growth by 50% (LD50) was 3.7 +/- 0.2 microM as measured by direct counting of survivors using a haemocytometer, 5.1 +/- 2.0 microM in a colorimetric test based on the formation of a formazan product, and 8.8 +/- 3.7 microM by estimation of pyruvate. The activity of the drug was enhanced by the addition of fatty-acid-free bovine serum albumin as a carrier protein to the culture medium at an optimal concentration of 5 mg/ml. Increasing amounts of the donor horse serum used for routine maintenance of these cultures, which is normally the only source of myristic acid for these trypanosomes, also affected the toxicity of the drug, in this case increasing the LD50.

A rapid method for sequencing trinucleotide repeats

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Correlation between the onset age of Huntington's disease and length of the trinucleotide repeat in IT-15

Huntington's disease (HD) is an autosomal dominant disorder with a variable age of onset that is influenced by the sex of the affected parent. The recent recognition that HD is caused by an expanded triplet repeat suggests the possibility that the onset age may be predicted by the length of the repeat. This hypothesis was tested by assaying the length of the repeat in 114 individuals who were clinically diagnosed with HD and had a known onset age. Every individual had an expanded allele. The range was from 36 to 82 repeats (mean = 48.4 +/- 9.51) and larger than the normal range (6 to 31). The size of the expanded allele was correlated with the age of onset (r = -0.65 p < .0001). Despite the highly significant correlation, the repeat size explains less than half of the variance in onset age. Furthermore, the age of onset cannot be predicted from the size of the triplet repeat, particularly if the number of repeats is in the smaller end of the expanded range. If the repeat is < or = 50 triplets, the amount of variation in the age of onset explained by the length of the triplet repeat is less than 10%. As an illustration, the onset age of individuals with 39 repeats ranges from 30 to 65 years old. The sex of the affected parent had no effect in our sample beyond the effect of the length of the repeat. Affected offspring of affected fathers had longer repeats and a larger variance in allele size than offspring of affected mothers, perhaps reflecting greater instability in paternal transmission.

Dissociative experiences and disorders among women who identify themselves as sexual abuse survivors

The purpose of the study was to identify dissociative experiences and disorders among women who are survivors of sexual abuse. Fifty-one women from two different centers who identified themselves as abuse survivors participated in the research interviews. The Dissociative Experiences Scale (DES) and the Dissociative Disorders Interview Schedule (DDIS) were used to collect data. The results indicated that 88.2% of the 51 women had a dissociative disorder of some type. Twenty-eight (54.9%) of the women had a DDIS diagnosis of multiple personality disorder (MPD). The women had high DES scores, a high number of secondary features of MPD, high rates of depression, borderline personality, substance abuse, somatic symptoms, Schneiderian symptoms, ESP/supernatural experiences, suicide attempts, and conversion symptoms. The vast majority of sexual abuse survivors in this sample have extensive dissociative symptomatology and related features. Therapists working with adult sexual abuse survivors should be knowledgeable about dissociation, should thoroughly assess a client's dissociative abilities, and should incorporate these findings into the therapy process.

A comparison of in vitro assay systems for the measurement of drug sensitivity of Trypanosoma evansi

Two in vitro assay systems were investigated for their effectiveness in detecting the sensitivity of Trypanosoma evansi stocks to the trypanocide suramin. These assay systems measured 1) incorporation of radiolabelled nucleic acid precursor, hypoxanthine; and 2) pyruvate production. They were compared with the direct counting method in which numbers of motile trypanosomes were estimated using a Neubauer haemocytometer chamber. Three stocks of T. evansi were tested-2 suramin sensitive stocks from Indonesia, TREU 1840 and TREU 1981, and a suramin resistant stock from the Sudan, TREU 2136. Each assay system distinguished between the suramin sensitive and resistant stocks. However, inhibition compared to untreated control cultures was less when assessed from pyruvate concentration in culture supernatants than by direct counting. The length of incubation with drug before addition of radio-label was the most important variable in the hypoxanthine incorporation assay. A pre-incubation time of 16 hours with the drug before adding the label for the further 8 hours of the assay was found to be the most sensitive. Under these conditions, the IC50 values (drug concentrations causing 50% inhibition) were similar to those obtained from direct counts. Pre-incubation of parasites with drug before adding the label resulted in a decrease of the IC50. These results suggest that the discrepancy between the levels of pyruvate production and relative growth at inhibitory concentrations of the drug are due to metabolism by the parasites during the initial stages of the assay, before the drug has began to inhibit cell growth.

Anticipation in bipolar affective disorder

Anticipation refers to the increase in disease severity or decrease in age at onset in succeeding generations. This phenomenon, formerly ascribed to observation biases, correlates with the expansion of trinucleotide repeat sequences (TNRs) in some disorders. If present in bipolar affective disorder (BPAD), anticipation could provide clues to its genetic etiology. We compared age at onset and disease severity between two generations of 34 unilineal families ascertained for a genetic linkage study of BPAD. Life-table analyses showed a significant decrease in survival to first mania or depression from the first to the second generation (P < .001). Intergenerational pairwise comparisons showed both a significantly earlier age at onset (P < .001) and a significantly increased disease severity (P < .001) in the second generation. This difference was significant under each of four data-sampling schemes which excluded probands in the second generation. The second generation experienced onset 8.9-13.5 years earlier and illness 1.8-3.4 times more severe than did the first generation. In additional analyses, drug abuse, deaths of affected individuals prior to interview, decreased fertility, censoring of age at onset, and the cohort effect did not affect our results. We conclude that genetic anticipation occurs in this sample of unilineal BPAD families. These findings may implicate genes with expanding TNRs in the genetic etiology of BPAD.

Genes with triplet repeats: candidate mediators of neuropsychiatric disorders

Recently a new form of human mutation-expansion of trinucleotide repeats-has been found to cause the diseases of fragile X syndrome, spinal and bulbar muscular atrophy, myotonic dystrophy and, most recently, Huntington's disease. We review the emerging data on the genetics and neurobiology of these disorders. Three are characterized by unusual patterns of inheritance, in particular, genetic 'anticipation', in which the severity of the disorder increases and the age of onset decreases in successive generations of a pedigree. Several idiopathic neuropsychiatric disorders have features of inheritance consistent with anticipation. In bipolar affective disorder, there is evidence for both earlier age of onset and more severe illness in the second generation of a subset of unilineal pedigrees. There is also the suggestion of anticipation in some forms of schizophrenia, spinocerebellar atrophy and autism. Triplet repeats are present in additional known genes, both in coding regions and untranslated regions. Furthermore, many novel genes with triplet repeats are expressed in the human brain, and these are candidates to cause some forms of these neuropsychiatric disorders.

Validity of the Dissociative Experiences Scale in screening for multiple personality disorder: a multicenter study

OBJECTIVE

The Dissociative Experiences Scale has proved a reliable and valid instrument to measure dissociation in many groups, but its capacity to distinguish patients with multiple personality disorder from patients with other psychiatric disorders has not yet been conclusively tested.

METHOD

A discriminant analysis was performed to classify 1,051 subjects as having or not having multiple personality disorder. Another discriminant analysis was performed on a subgroup of 883 subjects more closely representing patients in a typical psychiatric facility in terms of base rates of dissociative disorders. A cutoff score of 30 was also used to classify subjects, and Bayes's theorem, which allows for the calculation of the positive predictive value and the negative predictive value of a screening test, was applied.

RESULTS

According to discriminant analysis of the total study group, the scale's sensitivity was 76% and its specificity was also 76%; according to discriminant analysis of the more representative subgroup, the scale's sensitivity was 76% and its specificity was 85%. Use of the cutoff score of 30 produced similar results. Results of the application of Bayes's theorem showed that 17% of the subjects scoring 30 or higher would actually have multiple personality disorder and 99% of those scoring less than 30 would not have multiple personality disorder.

CONCLUSIONS

These results indicate that the Dissociative Experiences Scale performs quite well as a screening instrument to identify subjects with multiple personality disorder. In addition, the consistency of responses to scale items across centers indicates that the symptoms reported by patients with multiple personality disorder are highly similar across diverse geographic centers. This consistency supports the reliability and validity of the diagnosis of multiple personality disorder across centers.

Novel triplet repeat containing genes in human brain: cloning, expression, and length polymorphisms

Human genes containing triplet repeats may markedly expand in length and cause neuropsychiatric disease, explaining the phenomenon of anticipation (increasing severity or earlier age of onset in successive generations in a pedigree). To identify novel genes with triplet repeats, we screened a human brain cDNA library with oligonucleotide probes containing CTG or CCG triplet repeats. Fourteen of 40 clones encoded novel human genes, and 8 of these inserts have been sequenced on both strands. All contain repeats, and 5 of the 8 have 9 or more consecutive perfect repeats. All are expressed in brain. Chromosomal assignments reveal a distribution of these genes on multiple autosomes and the X-chromosome. Further, the repeat length in two of the genes is highly polymorphic, making them valuable index linkage markers. We predict that many triplet repeat-containing genes exist; screening with the CTG probe suggests approximately 50-100 genes containing this type of repeat are expressed in the human brain. Since additional disorders, such as Huntington's disease, bipolar affective disorder, and possibly others, show features of anticipation, we suggest that these novel human genes with triplet repeats are candidates for causing neuropsychiatric diseases.

Inositol 1,4,5-trisphosphate receptors: immunohistochemical localization to discrete areas of rat central nervous system

The second messenger inositol 1,4,5-trisphosphate triggers the release of intracellular Ca2+ stores upon binding to the inositol 1,4,5-trisphosphate receptor protein, a calcium channel that has been purified and molecularly cloned. To clarify the roles of inositol 1,4,5-trisphosphate receptor in the central nervous system, we have examined in detail the distribution of inositol 1,4,5-trisphosphate receptors in the rat brain and spinal cord using immunohistochemical methods. Inositol 1,4,5-trisphosphate receptors are present in neuronal cells, fibers and terminals in a wide distribution of areas throughout the central nervous system. These include a number of areas not previously reported, such as the olfactory bulb, thalamic nuclei and dorsal horn of the spinal cord. In addition, we have noted a strikingly high density of inositol 1,4,5-trisphosphate receptors in circumventricular organs and neuroendocrine structures such as the area postrema, choroid plexus, subcommisural organ, pineal gland and pituitary. The distribution of inositol 1,4,5-trisphosphate receptors in discrete structures throughout the central nervous system, including interconnected neuronal systems and neuroendocrine and circumventricular organ structures, presumably reflects the importance of Ca2+ release mediated by the phosphoinositide second messenger system in control of diverse physiological processes.

Inositol (1,4,5)-trisphosphate receptor: characterization of neuron-specific alternative splicing in rat brain and peripheral tissues

One source of diversity in the inositol (1,4,5)-trisphosphate receptors (IP3Rs) is generated at the level of alternative splicing. Our previous studies of splice isoforms of the receptor in various tissues suggested that some tissues, specifically those containing neurons, selectively express a 40 amino acid insert located between 2 sites for phosphorylation by cyclic AMP-dependent protein kinase (PKA), and that the presence of this insert changes the preferred site of phosphorylation of the receptor. Studies of the mouse receptor have also suggested the existence of intermediately spliced forms containing partial versions of the splice and exhibiting different brain distributions. In this study, we have investigated the alternative splicing of the rat receptor in greater detail using RNase protection and PCR analysis. We find little evidence for the existence of intermediately spliced forms in rat, raising the possibility that the degree of alternative splicing at this site differs in the brains of two very similar species. Our screen of tissue distribution supports the selectively neuronal expression of the long spliced form, and suggests that regulation of this receptor in neurons may be different than in other tissues.

Correlation of acute cocaine-induced changes in local cerebral blood flow with subjective effects

The authors administered 48 mg of intravenous cocaine or placebo to eight abstinent cocaine users in a double-blind, crossover design and examined blood flow using single photon emission computed tomography. Cocaine produced significant decreases in frontal cortical and basal ganglia blood flow; these latter correlated negatively with increases in self-ratings of "rush" and "high." The authors conclude that these local effects are compatible with dopaminergic system involvement.

Psychiatric health care costs of multiple personality disorder

The lifetime psychiatric health care costs of 15 women with multiple personality disorder (MPD) who were admitted to the senior author's inpatient service over a four-year period were tabulated. A calculation of the projected costs of treatment based on costs incurred since diagnosis was made, and this was compared to prediagnosis baseline costs projected forwards for ten years. The result of the calculation was a saving of $84,899.44 per patient over ten years due to the diagnosis and psychotherapeutic treatment of MPD. If the length of time in the health care system prior to diagnosis was reduced from the average of 98.77 months experienced by these 15 women to 12 months, the savings would be over $250,000.00 per case. Because the potential savings from the diagnosis and treatment of MPD appear to be so large, replication of the study with a longer followup is required.

Cloning and expression of a rat somatostatin receptor enriched in brain

The tetradecapeptide somatostatin (SRIF) is a hormone release-inhibiting substance that mediates diverse effects in brain and peripheral organs via specific receptors. A cDNA encoding a rat SRIF receptor was identified by use of degenerate oligonucleotide primers and polymerase chain reaction amplification of cDNA prepared from transcripts expressed in rat brain. The complete cDNA encodes a protein of 391 amino acids with seven potential transmembrane domains. Expression of the cDNA product in transfected COS-7 cell lines provides the same high affinity of binding to [125I-Tyr11]SRIF-14 as that of rat cerebral cortex tissues. However, the binding of [125I-Tyr11]SRIF-14 to cloned rat SRIF receptor is not displaced by MK678, a SRIF analog that partially displaces [125I-Tyr11]SRIF-14 binding sites in membranes of rat cerebral cortex. Northern analysis and in situ hybridization indicate that mRNA (4.0 kilobases) for cloned rat SRIF receptor is preferentially expressed in rat brain regions such as cerebral cortex and hippocampus with no detectable expression in most peripheral organs. This pattern contrasts with the exclusive peripheral expression of a recently cloned human SRIF receptor. The cDNA probe of rat receptor detects mRNA from mouse brain but not from human cerebral cortex and cerebellum.

Identification of the surface components of Trypanosoma evansi

125I-labelling was used to characterise the surface components of five stocks of Trypanosoma evansi. Two components of 67 and 60.5 kD were labelled in two of the stocks, a single 60.5 kD component in two other stocks and no components in the remaining stock. These differences are probably related to the labelling method and biochemical differences between the stocks.

Dissociative experiences among psychiatric inpatients

The Dissociative Experiences Scale was administered to 299 inpatients on an acute care general adult psychiatric ward over a 2-year period. The average score was 14.6, which is significantly higher than the mean for the general population. About one in six inpatients reported very high scores above 50 on the seven most common items in the scale, indicating a high level of dissociative psychopathology. Based on the responses to four items which form a scale factor called Activities of Dissociated States, an estimate is made that 6%-8% of general adult inpatients may have multiple personality disorder. Dissociative psychopathology is common on inpatient units.

Schneiderian symptoms and childhood trauma in the general population

The Dissociative Disorders Interview Schedule (DDIS) was administered to a sample of 502 adults in the city of Winnipeg, Manitoba, Canada. Findings indicate that Schneiderian symptoms are highly related to childhood trauma and other dissociative symptoms clusters in the general population, as they are in clinical populations. Implications of the findings are discussed.