Pharmacological properties of the potent epileptogenic amino acid dysiherbaine, a novel glutamate receptor agonist isolated from the marine sponge Dysidea herbacea

Dysiherbaine (DH) is a marine sponge-derived amino acid that causes seizures upon injection into mice. In this report we investigate the behavioral effects and characterize the pharmacological activity of DH. DH induced convulsive behaviors in mice with ED(50) values of 13 pmol/mouse, i.c.v. and 0.97 mg/kg, i.p. In rat brain synaptic membranes DH displaced binding of [3H]kainic acid (KA) and [3H]alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) with K(i) values of 26 and 153 nM, respectively; in contrast, DH did not displace the N-methyl-D-aspartic acid (NMDA) receptor ligand [3H]CGS-19755. DH displaced [3H]KA from recombinant GluR5 and GluR6 kainate receptor subunits expressed in HEK293 cells with K(i) values of 0.74 and 1.2 nM, respectively. In whole-cell voltage-clamp recordings from cultured rat hippocampal neurons, DH evoked inward currents from both AMPA and KA receptors with EC(50) values of 9.7 microM and 210 nM, respectively. AMPA receptor currents were blocked by GYKI 53655, whereas KA receptor currents were blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). Surprisingly, in calcium imaging experiments we found that DH also activated recombinant mGluR5 receptors but did not activate mGluR1 receptors. DH did not activate glutamate transporters or gamma-aminobutyric acid A (GABA(A)) receptors. These results indicate that DH is a potent non-NMDA-type agonist with very high affinity for KA receptors, as well as a subtype-selective mGluR agonist. DH possesses the most potent epileptogenic activity among the amino acids yet identified. This novel excitatory amino acid may prove useful for evaluating the physiological and pathological roles of non-NMDA receptors, especially KA receptors, in the central nervous system.

Love matters. A profile of Connecticut Hospice

After 25 years, America's first hospice looks back at its past challenges and successes, and looks forward to continuing its mission into the 21st century.

Early detection of reverse transcriptase activity in plasma of neonates infected with HIV-1: a comparative analysis with RNA-based and DNA-based testing using polymerase chain reaction

Plasma viral load from 71 HIV-1-infected neonates was measured by using Amp-RT, an ultrasensitive quantitative reverse transcriptase (RT) assay and by nucleic acid sequence-based amplification (NASBA), an RNA-based quantitative assay. Results were then compared with those obtained from detection of proviral DNA in peripheral blood mononuclear cells (PBMCs) by polymerase chain reaction (PCR) using Turnbull analysis. At 5 days of life, 50% of neonates were positive by Amp-RT, 30% were NASBA positive, and 20% were DNA-PCR positive. Through the first 12 days of life, Amp-RT was more sensitive than either NASBA or DNA-PCR in detecting HIV-1 infection. Amp-RT values correlated well with NASBA RNA values, with an overall Pearson's r = 0.63 (95% confidence interval [CI], 0.40-0.78). In proportional hazards analysis of infants aged 14 to 61 days (N = 31), a one-log increase in RNA-based viral load was associated with a > fivefold risk of disease progression when using the U.S. Centers for Disease Control and Prevention (CDC) clinical Category C (CDC-C) or death as an endpoint (p =.014). Kaplan-Meier analysis of these data found that RNA viral loads were able to predict disease progression using CDC-C/death as an endpoint (p = .013). Early quantitative viral load measurements may assist clinicians in diagnosing HIV-1 infection, stratifying risk of disease progression, and implementing a treatment plan using highly active antiretroviral therapy for infants within the first few weeks of life.

Exploring the sexual histories of older GUM clinic attenders

Little is known either of the factors motivating clinic attendance in later life, or the sexual health histories of older clinic attenders. A self-administered questionnaire study linked to patient note data aiming to explore these issues was undertaken within 3 genitourinary medicine (GUM) clinics in the Trent region. Participants comprised 224 individuals aged 50 years and older attending the 3 clinics during the study period. The majority of study participants were attending the clinic with a suspected sexually transmitted infection (STI) (n = 145, 64.7%) and approximately half (n=119, 53.1%) were first-time GUM clinic attenders. Data available for participants recruited from the Sheffield clinic indicated that, although the majority of participants reported having had only one sexual partner during the last 12 months, a significant minority reported considerably higher numbers of partners, including those classed 'higher risk' for STI acquisition. These data indicate that older people engage in behaviours that place them at risk of STI acquisition and many attend GUM clinics for the first time in later life.

Acetochlor-induced rat nasal tumors: further studies on the mode of action and relevance to humans

The herbicide acetochlor, and its analogue alachlor, have similar toxicological properties, the most significant being the induction of nasal adenomas in rats in 2-year feeding studies. Previous investigations have proposed a mode of action involving metabolism to a quinone-imine, the formation of protein adducts, cell death, and compensatory hyperplasia leading to the observed adenomas. Comparisons between rats and humans of the metabolic cascade leading to the quinone-imine indicate that these chemicals do not pose a threat to humans. Further investigations with acetochlor, presented here, have revealed an additional activation pathway in which a sulfoxide metabolite of acetochlor plays a key role. The sulfoxide was found to be the major plasma metabolite in rats dosed with acetochlor. Whole-body autoradiography studies established that this metabolite selectively accumulates and persists in the olfactory epithelium of rats. Radiolabeling of the sulfoxide molecule in the phenyl ring and in the sulfoxide side-chain demonstrated that the metabolite accumulating in nasal tissues retains the sulfoxide side-chain. The formation of a quinone-imine from the sulfoxide was facilitated by hydroxylation of the phenyl ring by a cytochrome P450 isoenzyme which was specific to the nasal epithelium in the rat. This metabolic conversion could not be detected in 33 fresh human nasal tissue samples, supporting the earlier view that the acetochlor-induced rat nasal tumors do not represent a hazard for humans.

Genomewide search in Canadian families with inflammatory bowel disease reveals two novel susceptibility loci

The chronic inflammatory bowel diseases (IBDs)-Crohn disease (CD) and ulcerative colitis (UC)-are idiopathic, inflammatory disorders of the gastrointestinal tract. These conditions have a peak incidence in early adulthood and a combined prevalence of approximately 100-200/100,000. Although the etiology of IBD is multifactorial, a significant genetic contribution to disease susceptibility is implied by epidemiological data revealing a sibling risk of approximately 35-fold for CD and approximately 15-fold for UC. To elucidate the genetic basis for these disorders, we undertook a genomewide scan in 158 Canadian sib-pair families and identified three regions of suggestive linkage (3p, 5q31-33, and 6p) and one region of significant linkage to 19p13 (LOD score 4.6). Higher-density mapping in the 5q31-q33 region revealed a locus of genomewide significance (LOD score 3.9) that contributes to CD susceptibility in families with early-onset disease. Both of these genomic regions contain numerous genes that are important to the immune and inflammatory systems and that provide good targets for future candidate-gene studies.

Building a "brain attack" team to administer thrombolytic therapy for acute ischemic stroke

Before tissue plasminogen activator (tPA) was licensed for use in Canada, in February 1999, the Calgary Regional Stroke Program spearheaded the development and organization of local resources to use thrombolytic therapy in patients who had experienced acute ischemic stroke. In 1996 special permission was obtained from the Calgary Regional Health Authority to use intravenously administered tPA for acute ischemic stroke, and ethical and scientific review boards approved the protocols. After 3 years our efforts have resulted in improved patient outcomes, shorter times from symptom onset to treatment and acceptable adverse event rates. Areas for continued improvement include the door-to-needle time and broader education of the public about the symptoms of acute ischemic stroke.

Trichloroethylene induced vitamin B(12) and folate deficiency leads to increased formic acid excretion in the rat

Exposure of rats to trichloroethylene induces a sustained excretion of large amounts of formic acid in urine. Both of the major metabolites, trichloroethanol and trichloroacetic acid, were found to induce this response, but not the minor metabolite S-(1, 2-dichlorovinyl) cysteine. Other polychlorinated solvents, including carbon tetrachloride and chloroform, also increased urinary formate excretion. Addition of folic acid either to diet or drinking water modulated the response indicating that these rats were folate deficient. Two markers of vitamin B(12) deficiency, methylmalonic acid and 5-methyltetrahydrofolate, were also markedly increased in urine and plasma respectively. The increase in 5-methyltetrahydrofolate is consistent with a folate deficiency caused by an inhibition of the vitamin B(12) dependent methionine salvage pathway. Since both vitamin B(12) and chemicals containing polychlorinated carbon atoms readily form free radicals, it is suggested that trichloroacetic acid and trichloroethanol interact with vitamin B(12) through a free radical mechanism inducing a B(12) deficiency and, as a consequence, a folate deficiency. As a result of the folate deficiency, excess formic acid, which is normally utilised through this pathway, is excreted in urine.

Psychiatric manifestations of systemic illness

Many behavioral manifestations of systemic disease exist, including delirium, psychosis, mania, catatonia, depression, and anxiety. The features and medical causes of each of those manifestations are described. The indications from history and physical examination that suggest underlying medical illness are reviewed. The psychiatric presentations of several specific conditions are discussed in detail.

Pulmonary toxicity and carcinogenicity of trichloroethylene: species differences and modes of action

Trichloroethylene (TCE) is both acutely toxic and carcinogenic to the mouse lung following exposure by inhalation. In contrast, it is not carcinogenic in the rat lung and is markedly less toxic following acute exposure. Toxicity to the mouse lung is confined almost exclusively to the nonciliated Clara cell and is characterized by vacuolation and increases in cell replication. Chloral, a metabolite of TCE that accumulates in Clara cells and has been shown to be the cause of the toxicity, also causes aneuploidy in some test systems. Cytotoxicity, increased cell division, and aneuploidy are known risk factors in the development of cancer and provide a plausible mode of action for TCE as a mouse lung carcinogen. All acute and chronic effects of TCE on the mouse lung are believed to be a direct consequence of high cytochrome P450 activity and impaired metabolism of chloral in Clara cells. Comparisons between species suggest that the ability of the human lung to metabolize TCE is approximately 600-fold less than that in the mouse. In addition, the human lung differs markedly from the mouse lung in the number and morphology of its Clara cells. Thus, the large quantitative differences between the metabolic capacity of the mouse lung and the human lung, together with the species differences in the number and morphology of lung Clara cells, suggest that the risks to humans are minimal and that other tumor sites should take precedent over the lung when assessing the potential risks to humans exposed to TCE.

Lipoprotein subpopulation distributions in lean, obese, and type 2 diabetic women: a comparison of African and white Americans

OBJECTIVE

Abnormal subpopulation distributions of plasma lipoproteins have been reported in white American (WA) women with obesity and type 2 diabetes that explain part of the elevated rate of cardiovascular disease in these patients. This study examined if these perturbations also occur in obese and diabetic African American (AA) women and compared the lipoprotein profiles with WA counterparts.

RESEARCH METHODS AND PROCEDURES

We determined the lipoprotein subpopulation distribution in the plasma of 51 lean women (29 WA, 22 AA, body mass index [BMI] < 30), 50 obese women (27 WA, 23 AA, BMI > 30), and 43 obese women with type 2 diabetes (27 WA, 16 AA), by nuclear magnetic resonance spectroscopy.

RESULTS

AA diabetic women, like WA diabetic women, had a larger average very low density lipoprotein (VLDL) size, elevated levels of small low density lipoprotein cholesterol (LDL-C), and lower levels of small high density lipoprotein cholesterol (HDL-C), when compared to lean controls (p<0.05). These differences were accompanied by higher VLDL-triglycerides (TG) and LDL-C in WA (p<0.05), but not in AA. Although the effects of obesity and diabetes on lipoprotein subpopulation were fairly similar for AA and WA, some racial differences, particularly with respect to HDL, were observed.

DISCUSSION

The atherogenic perturbations in lipoprotein profiles of obese AA women, particularly those with diabetes, were relatively similar to those found in WA women and may be contributing to the increased rate of cardiovascular disease (CVD) in AA with obesity and diabetes. The parameters of subpopulation distribution may provide better markers for CVD than lipid concentrations alone, particularly in AA women. Furthermore, subtle racial differences in lipoprotein profiles suggest that race-specific criteria may be needed to screen patients for CVD.

Comparison of the internal transcribed spacer, ITS-1, from Sarcocystis falcatula isolates and Sarcocystis neurona

The genetic diversity among 6 Sarcocystis falcatula isolates derived from geographically distinct regions in the U.S.A. was detected using the first internal transcribed spacer region 1 (ITS-1) of the rRNA gene. These sequences were then compared to the full sequence from a Sarcocystis neurona isolate obtained from a California horse diagnosed with equine protozoal myeloencephalitis. No nucleotide differences were detected over partial sequence analysis of 2 additional S. neurona isolates: however, the complete nucleotide sequence for the ITS-1 region was not compared. Twelve nucleotide differences were consistently detected when aligned sequences of S. neurona were compared to those of the S. falcatula isolates. Additional nucleotide base changes were detected among the S. falcatula isolates, but these changes were not consistent in all the S. falcatula isolates. These results indicate that S. falcatula may be comprised of a heterogeneous population and that the ITS-1 region can be used to distinguish S. neurona from S. falcatala used in this study.

Effects of reduced ankle dorsiflexion following lateral ligament sprain on temporal and spatial gait parameters

Partial rupture of the lateral ligament complex of the ankle is the commonest soft tissue injury affecting the lower limb. The effect of the limitation of motion at the ankle, particularly of dorsiflexion, on gait is unclear. In this study, 34 subjects were measured during their recovery from a partial rupture of the lateral ligament for both range of dorsiflexion and the temporal and spatial parameters of walking. Consistent relationships were identified between the range and the gait variables which were in concordance with the characteristics expected from an antalgic gait pattern.

Absence of linkage between inflammatory bowel disease and selected loci on chromosomes 3, 7, 12, and 16

BACKGROUND & AIMS

Linkage data derived from genome-wide scans of inflammatory bowel disease (IBD) sibling-pair families have identified 4 loci on chromosomes 3, 7, 12, and 16 as potential sites for IBD susceptibility genes. The aim of this study was to investigate whether linkage analysis of another independently collected set of sibling pairs with IBD would provide further evidence of linkage between these previously reported loci and IBD.

METHODS

Using the MAPMAKER/SIBS program, the segregation of 21 microsatellite marker loci spanning the 4 putative IBD gene loci was analyzed in a study population comprising 161 families with 114 Crohn's disease, 36 ulcerative colitis, and 50 mixed IBD sibling pairs from the Greater Toronto area.

RESULTS

The results of multipoint linkage analysis showed no evidence for linkage between IBD and each of the 21 marker loci studied; the logarithm of odds scores in all instances were less than 0.8. These linkage data were found, by exclusion mapping analysis, to exclude values of lambdas ranging from 1.5 to 3.0, depending on the locus evaluated.

CONCLUSIONS

The loci previously suggested as representing IBD susceptibility loci are not linked to IBD in the Toronto population examined in this analysis.

Increased bioactivation of dihaloalkanes in rat liver due to induction of class theta glutathione S-transferase T1-1

A characteristic feature of the class Theta glutathione S-transferase (GST) T1-1 is its ability to activate dichloromethane and dibromoethane by catalysing the formation of mutagenic conjugates. The level of the GSTT1 subunit within tissues is an important determinant of susceptibility to the carcinogenic effects of these dihaloalkanes. In the present study it is demonstrated that hepatic GST activity towards these compounds can be elevated significantly in female and male Fischer-344 rats by feeding these animals on diets supplemented with cancer chemopreventive agents. Immunoblotting experiments showed that increased activity towards the dihaloalkanes is associated with elevated levels of the GSTT1 subunit in rat liver. Sex-specific effects were observed in the induction of GSTT1 protein. Amongst the chemopreventive agents tested, indole-3-carbinol proved to be the most potent inducer of hepatic GSTT1 in male rats (6.2-fold), whereas coumarin was the most potent inducer of this subunit in the livers of female rats (3. 5-fold). Phenobarbital showed significant induction of GSTT1 only in male rat liver and had little effect in female rat liver. Western blotting showed that class Alpha, Mu and Pi GST subunits are not co-ordinately induced with GSTT1, indicating that the expression of GSTT1 is determined, at least in part, by mechanisms distinct from those that regulate levels of other transferases. The increase in amount of hepatic GSTT1 protein was also reflected by an increase in the steady-state level of mRNA in response to treatment with chemopreventive agents and model inducers. Immunohistochemical detection of GSTT1 in rat liver supported the Western blotting data, but showed, in addition to cytoplasmic staining, significant nuclear localization of the enzyme in hepatocytes from some treated animals, including those fed on an oltipraz-containing diet. Significantly, the hepatic level of cytochrome P-450 2E1, an enzyme which offers a detoxification pathway for dihaloalkanes, was unchanged by the various inducing agents studied. It is concluded that the induction of GSTT1 by dietary components and its localization within cells are important factors that should be considered when assessing the risk dihaloalkanes pose to human health.

Familial eosinophilia maps to the cytokine gene cluster on human chromosomal region 5q31-q33

Familial eosinophilia (FE) is an autosomal dominant disorder characterized by peripheral hypereosinophilia of unidentifiable cause with or without other organ involvement. To localize the gene for FE, we performed a genomewide search in a large U.S. kindred, using 312 different polymorphic markers. Seventeen affected subjects, 28 unaffected bloodline relatives, and 8 spouses were genotyped. The initial linkage results from the genome scan provided evidence for linkage on chromosome 5q31-q33. Additional genotyping of genetic markers located in this specific region demonstrated significant evidence that the FE locus is situated between the chromosome 5q markers D5S642 and D5S816 (multipoint LOD score of 6.49). Notably, this region contains the cytokine gene cluster, which includes three genes-namely, those for interleukin (IL)-3, IL-5, and granulocyte/macrophage colony-stimulating factor (GM-CSF)-whose products play important roles in the development and proliferation of eosinophils. These three cytokine genes were screened for potential disease-specific mutations by resequencing of a subgroup of individuals from the present kindred. No functional sequence polymorphisms were found within the promoter, the exons, or the introns of any of these genes or within the IL-3/GM-CSF enhancer, suggesting that the primary defect in FE is not caused by a mutation in any one of these genes but, rather, is caused by another gene in the area.

Preparation and beliefs of graduates of a predoctoral infant oral health clinical program

PURPOSE

The aim of this study is to evaluate the effects of a predoctoral clinical educational program on preparation and beliefs of participants related to infant oral health.

METHODS

Questionnaires were constructed and mailed out to four classes of past dental students, two of which had attended the program.

RESULTS

Significant differences were detected between groups regarding their feelings of preparation for examination procedures in children younger than 36 months and their beliefs regarding appropriate age of the initial dental visit.

Role of female sex steroids in regulating cholesteryl ester transfer protein in transgenic mice

The role of sex steroids in the regulation of cholesteryl ester transfer protein (CETP) was examined in the following groups of female transgenic mice carrying the human CETP gene: (1) normal, (2) ovariectomized, (3) ovariectomized and treated with estrogen; (4) ovariectomized and treated with progesterone; (5) ovariectomized and treated with both hormones, and (6) ovariectomized and treated with tamoxifen. CETP activity was measured in the plasma, and in the particulate and the soluble fractions of liver, muscle, and adipose tissue. Human CETP specific activity was determined by taking the difference of cholesterol ester transfer in the presence and absence of an antibody (TP2) against human CETP Ovariectomy reduced hormone levels, but did not completely abolish them from the circulation. Plasma CETP activity was significantly reduced in the tamoxifen group. There were significant reductions in CETP in liver homogenate and the soluble fraction, as well as in the particulate fraction of adipose with ovariectomy. Hormone replacement did not restore CETP activity in either the plasma or the tissues. Tamoxifin treatment resulted in a decrease in CETP activity in both fractions of liver, but had no effect on adipose. In the soluble fraction of adipose tissue and both fractions of muscle, only trace CETP activity was detected. We conclude that (1) minimal amounts of sex steroid hormones may be sufficient to affect CETP expression; (2) the effects of sex steroid hormones vary among tissues; and (3) in addition to the sex steroids, factor(s) from the ovary are needed for the full expression of CETP in this animal model.

Direct effects of metabotropic glutamate receptor compounds on native and recombinant N-methyl-D-aspartate receptors

The actions of glutamate in the central nervous system are mediated through interaction with fast activating ionotropic receptors and G protein-coupled metabotropic glutamate receptors (mGluRs). Studies of these receptors have relied on the availability of agonists and antagonists selective for each receptor class. Compounds that were thought to be selective for mGluRs have been extensively used to study the role of these receptors in the brain. Their use has implicated mGluRs in a wide range of physiological and pathological processes including the modulation of N-methyl-D-aspartate (NMDA) receptors and NMDA receptor-dependent processes. We report that some of the most commonly used mGluR compounds act as antagonists on NMDA receptors at concentrations commonly used to activate or block mGluRs. In addition, several of the drugs also act as agonists at higher concentrations due at least in part to high levels of contaminant amino acids. Our results indicate that caution should be used when using these drugs to study the roles of mGluRs in various NMDA-dependent processes. The antagonist effects were dependent on the concentration of the NMDA receptor coagonists, preventing reappraisal of previously published work.