Severe mental illness and substance misuse.
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Diagnosis, Dual (Psychiatry)↗
Biomedical subjects
T Weaver
Publications and source records attributed to T Weaver.
Ventral hippocampal ibotenic acid lesions block chronic nicotine-induced spatial working memory improvement in rats.
Chronic nicotine infusions have been found to significantly improve working memory performance in the radial-arm maze. This effect is blocked by co-infusions of the nicotinic antagonist mecamylamine. Acute nicotine injections also improve working memory performance in the radial-arm maze. This effect is also blocked by mecamylamine co-administration. Recent local infusions studies have demonstrated the importance of the ventral hippocampus for nicotinic involvement in memory. Local infusions of mecamylamine, DHbetaE or MLA impair working memory performance on the radial-arm maze. The current study was conducted to determine the importance of the ventral hippocampus for the chronic effects of nicotine. Rats were trained on the working memory task in an eight-arm radial maze. After acquisition they underwent either infusions of ibotenic acid lesions or vehicle infusions and received subcutaneous implants of osmotic minipumps that delivered either nicotine at a dose of 5 mg kg-1 day-1 or vehicle in a 2x2 design. The rats then were given 2 days of recovery and were tested on the radial-arm maze three times per week for the next 4 weeks. As seen in previous studies, in the sham lesioned group nicotine infusions caused a significant improvement in choice accuracy. In contrast no nicotine-induced improvement was seen in the rats after ibotenic acid lesions of the ventral hippocampus. The effect of nicotine was blocked even though this lesion did not cause a deficit in performance. Previous work showed that chronic nicotine infusion still caused a significant improvement in working memory performance in the radial-arm maze after knife-cut lesions of the fimbria-fornix carrying the septo-hippocampal cholinergic innervation. Thus it appears that it is the postsynaptic nicotinic receptors in the ventral hippocampus which are critically important for the expression of the chronic nicotine induced working memory improvement.
Animals↗
Crystal structures of native and recombinant yeast fumarase.
Crystal structures for both native and recombinant forms of yeast fumarase from Saccharomyces cerevisiae have been completed to moderate resolution by two separate laboratories. The recombinant form was obtained by the construction of an expression plasmid for Escherichia coli. Despite a high level of amino acid sequence similarity, purification of the eukaryotic enzyme from the wild-type prokaryotic enzyme was feasible. The crystal structure of the native form, NY-fumarase, encompasses residues R22 through M484, while the recombinant form, RY-fumarase, consists of residues S27 through L485. Both crystal structures lack the N-terminal translocation segment. Each subunit of the homo-tetrameric protein has three domains. The active site is formed by segments from each of three polypeptide chains. The results of these studies on the eukaryotic proteins are unique, since the recombinant form was done in the absence of dicarboxylic acid and has an unoccupied active site. As a comparison, native fumarase was crystallized in the presence of the competitive inhibitor, meso-tartrate. Meso-tartrate occupies a position close to that of the bound citrate molecule found in the active site of the E. coli enzyme. This inhibitor participates in hydrogen bonding to an active-site water molecule. The independent determination of the two structures provides further evidence that an active-site water molecule may play an active role in the fumarase-catalyzed reaction.
Binding Sites↗
Nicotine-dizocilpine interactions and working and reference memory performance of rats in the radial-arm maze.
Both nicotinic cholinergic and NMDA glutaminergic systems are important for memory function. Nicotine has been found repeatedly to significantly improve working memory performance in the radial-arm maze. The NMDA antagonist dizocilpine has been found to impair working memory performance. There is neuropharmacological evidence that these two systems are functionally related. Nicotine is potent at releasing many transmitters including glutamate. The current study was conducted to examine the interaction of nicotinic and NMDA systems with regard to working and reference memory. Rats were trained on a working/reference procedure on a 16-arm radial maze. After acquisition, they were administered nicotine (0, 0.2, and 0.4 mg/kg) and dizocilpine (0, 100, and 200 microg/kg) alone or in combination in a repeated measures, counterbalanced design. As seen previously, nicotine at a dose of 0.2 mg/kg caused a significant improvement in working but not reference memory performance in the radial-arm maze. The 200 microg/kg dose of dizocilpine made the rats nonresponsive on the maze so that choice accuracy could not be assessed. The 100 microg/kg dose of dizocilpine caused significant impairments in both working and reference memory. The 0.4 mg/kg dose of nicotine significantly attenuated the dizocilpine-induced deficit in both working and reference memory. NMDA blockade impairs working and reference memory and blocks the expression of the working memory improvement caused by 0.2 mg/kg of nicotine. However, a higher dose of 0.4 mg/kg of nicotine is effective at attenuating the dizocilpine-induced deficit, even though this dose alone is not effective in improving performance. A second study examined the effects of a lower dose range of dizocilpine. Comensurately smaller memory impairments were seen with lower doses of dizocilpine down to 12.5 microg/kg, which did not produce any significant effects on memory performance or response latency. Nicotine had a more modest effect in attenuating the smaller deficits caused by these lower doses of dizocilpine. These studies provide evidence for important interactions between nicotinic and NMDA systems with regard to memory function.
Animals↗
Mammalian BUB1 protein kinases: map positions and in vivo expression.
The spindle assembly checkpoint modulates the timing of anaphase initiation in mitotic cells containing improperly aligned chromosomes and increases the probability of successful delivery of a euploid chromosome set to each daughter cell. We have characterized cDNA sequences from several organisms with highly significant predicted protein sequence homologies to Saccharomyces cerevisiae Bub1p, a protein required for function of the spindle assembly checkpoint in budding yeast. The localization of mouse and human orthologs is in agreement with known conservation of synteny. Mouse backcross mapping data indicate that the murine gene resides on chromosome 2 near IL1A, 73 cM from the mouse centromere. Radiation hybrid mapping data indicate that the human locus exhibits linkage to microsatellite marker D2S176, which is located within 10 cM of human IL1A. Multiple-tissue Northern analysis indicates conservation of expression pattern in mouse and human with markedly high mRNA levels in testis. Northern analysis of two different spindle assembly checkpoint protein gene products from human, BUB1 and MAD2, reveals an expression pattern with common tissue distribution consistent with roles in a common pathway. In addition, we demonstrate that an mRNA found to accumulate in a rat fibroblast cell transformation system encodes rat BUB1, and we find that rat BUB1 mRNA accumulation correlates with the proliferation status of cells in culture.
Amino Acid Sequence↗
Impact of a dedicated service for male mentally disordered remand prisoners in north west London: retrospective study.
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Health Facilities↗
Mutations of fumarase that distinguish between the active site and a nearby dicarboxylic acid binding site.
Two mutant forms of fumarase C from E. coli have been made using PCR and recombinant DNA. The recombinant form of the protein included a histidine arm on the C-terminal facilitating purification. Based on earlier studies, two different carboxylic acid binding sites, labeled A- and B-, were observed in crystal structures of the wild type and inhibited forms of the enzyme. A histidine at each of the sites was mutated to an asparagine. H188N at the A-site resulted in a large decrease in specific activity, while the H129N mutation at the B-site had essentially no effect. From the results, we conclude that the A-site is indeed the active site, and a dual role for H188 as a potential catalytic base is proposed. Crystal structures of the two mutant proteins produced some unexpected results. Both mutations reduced the affinity for the carboxylic acids at their respective sites. The H129N mutant should be particularly useful in future kinetic studies because it sterically blocks the B-site with the carboxyamide of asparagine assuming the position of the ligand's carboxylate. In the H188N mutation at the active site, the new asparagine side chain still interacts with an active site water that appears to have moved slightly as a result of the mutation.
Binding Sites↗
Genome cross-referencing and XREFdb: implications for the identification and analysis of genes mutated in human disease.
Comparative genomics approaches and multi-organismal biology are valuable tools for genetic analysis. Cross-species connections between genes mutated in human disease states and homologues in model organisms can be particularly powerful, as model-organism gene function data and experimental approaches can shed light on the molecular mechanisms defective in the disease. We describe a project that is systematically identifying novel expressed sequence tag (EST) sequences that are highly related to genes in model organisms and mapping them to positions on the mouse and human maps. This process effectively cross-references model organism genes with mapped mammalian phenotypes, facilitating the identification of genes mutated in human disease states via the positional candidate approach. A public database, XREFdb (http:@www.ncbi.nlm.nih.gov/XREFdb/), disseminates similarity search, mapping and mammalian phenotype information and increases the rate at which these cross-species connections are established.
Animals↗
The Bentham Unit: a pilot remand and assessment service for male mentally disordered remand prisoners. II: Report of an independent evaluation.
BACKGROUND: Findings are presented from an evaluation of a pilot remand and assessment service--the Bentham Unit. The aims of the Bentham Unit are to provide rapid assessment, identify mentally disordered remand prisoners, and speed their transfer from prison to NHS care, where a need is indicated. METHOD: The number, rate and speed of referral, assessment and transfer to NHS care of offenders remanded to Wormwood Scrubs prison during periods before and after the Bentham Unit opened were compared. RESULTS: The service attracted a large volume of referrals. Between the two periods, significant increases in the numbers of referrals and hospital disposals, and major reductions in the interval between reception on remand into the prison, NHS assessment and transfer to NHS care, were observed. CONCLUSIONS: The aims of the unit were met. Implications for service configurations are discussed.
England↗
Crystallographic studies of the catalytic and a second site in fumarase C from Escherichia coli.
Fumarase C catalyzes the stereospecific interconversion of fumarate to L-malate as part of the metabolic citric acid or Kreb's cycle. The recent three-dimensional structure of fumarase C from Escherichia coli has identified a binding site for anions which is generated by side chains from three of the four subunits within the tetramer (Weaver et al., 1995). These same side chains are found in the three most highly conserved regions within the class II fumarase superfamily. The site was initially characterized by crystallographic studies through the binding of a heavy atom derivative, tungstate. A number of additional crystallographic structures using fumarase crystals with bound inhibitors and poor substrates have now been studied. The new structures have both confirmed the originally proposed active site, site A, and led to the discovery of a novel second binding site that is structurally nearby, site B. Site A utilizes a combination of residues, including H188, T187, K324, N326, T100, N141, S139, and S140, to form direct hydrogen bonds to each of the inhibitors. The A-site has been demonstrated by studying crystalline fumarase with the bound competitive inhibitors-citrate and 1,2,4,5-benzenetetracarboxylic acid. The crystal structure of fumarase C with beta-(trimethylsilyl)maleate, a cis substrate for fumarase, has led to the discovery of the second site or B-site. Sites A and B have different properties in terms of their three-dimensional structures. Site B, for example, is formed by atoms from only one of the subunits within the tetramer and mainly by atoms from a pi-helix between residues H129 through N135. The crystal structures show that the two locations are separated by approximately 12 A. A highly coordinated buried water molecule is also found at the active or A-site. The high-resolution crystal structures describe both sites, and atoms near the A-site are used to propose a likely enzyme/substrate complex.
Amino Acid Sequence↗
Combining qualitative studies with randomised controlled trials is often useful.
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Case Management↗
Assessment of in vivo attachment/phagocytosis by alveolar macrophages.
Alveolar macrophages (AMs) are recognized as an important first line of cellular host defense within the lung. Although mechanisms underlying AM response to microorganisms or particulates are well characterized in vitro, experimental approaches to the study of AMs in vivo are limited. To circumvent these limitations, a new assay was developed using fluorescently labelled liposomes or Pneumocystis carinii (PC) organisms which were administered intratracheally into mechanically ventilated rats. After 30 min, the lungs were lavaged and the percentage of administered liposomes or PC bound to AMs was determined by quantifying fluorescence. Factors known to enhance attachment/phagocytosis by AMs in vitro were assayed to determine their effect in vivo. For example, vitronectin (VN)-coated liposomes increased attachment from 25.2 +/- 2.4% to 47.2 +/- 3.0% (p < 0.001), while addition of VN increased the binding of PC to AMs from 16.5 +/- 1.7% to 24.5 +/- 2.2% (p < 0.05). Confocal laser microscopy of cells obtained by lavage provided morphologic evidence of attachment/phagocytosis by AMs. This model will permit the quantitative assessment of the interaction of fluorescently labelled liposomes or microorganisms with AMs in the lower respiratory tract of living animals.
Animals↗
General practitioners' immediate management of men presenting with urethral symptoms.
OBJECTIVES: To describe the immediate reported management, by general practitioners (GPs), of men presenting with symptoms of urethral discharge, or dysuria only. SUBJECTS: All 692 GPs in practice in Brent, Harrow, Ealing, Hammersmith, and Hounslow (UK). METHOD: Data were collected using a GP completed questionnaire concerning the management of the last male patient seen, aged less than 40 years, complaining of urethral discharge, and the last male patient under 40 years complaining of dysuria only. RESULTS: The response rate among GPs was 52%. Fifty three per cent of men with urethral symptoms, 86% of men with a urethral discharge and 24% with dysuria only, were identified by GPs and referred without investigation or treatment to a genitourinary medicine clinic. Of men with dysuria only, 93% of investigations by GPs were reported to include a mid-stream urine (MSU) specimen for bacteriology, and 19% a urethral swab for chlamydia. Seventy eight per cent of GPs reported using treatments with a broad spectrum antibiotic, 53% with trimethoprim, whilst 14% of GPs reported using a tetracycline in common use to treat non-gonococcal urethritis. Urine specimens were reported to be "culture positive" in 41% of men who had an MSU specimen tested, and 15% of men who had a urethral swab tested were reported to be chlamydia positive. CONCLUSION: The GPs included in this study were not a full sample, or representative of all the GPs, and the data are retrospective. Nevertheless, we found a large difference in GPs reported management for men with urethral symptoms according to whether or not urethral discharge was a reported complaint. Reported management is likely to be, at least, indicative of actual management. Therefore, the results suggest that assessment by GPs of men presenting with dysuria should be explored and more appropriate management strategies defined.
Adolescent↗
Congestive heart failure and disorders of the heart beat.
Cardiovascular disease is the leading cause of death in the United States. Congestive heart failure (CHF) is often the result of many non-fatal heart problems. Many patients who suffer from heart failure die as a result of cardiac dysrhythmias. This article discusses the normal heart, the changes from normal seen in CHF and dysrhythmias, the medical management of these conditions, including medications used, and the implications for the dental management of these patients.
Angiotensin-Converting Enzyme Inhibitors↗
Treating mentally disordered prisoners. Solution to treating prisoners in hospital is financial.
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Adult↗
Practice guidelines for medical nutrition therapy provided by dietitians for persons with non-insulin-dependent diabetes mellitus. International Diabetes Center.
Nutrition practice guidelines define a systematic approach for medical nutrition therapy (MNT) provided by dietitians and are derived from scientific evidence and expert opinion. Nutrition practice guidelines for persons with non-insulin-dependent diabetes mellitus (NIDDM) can be implemented for those with newly diagnosed or previously diagnosed NIDDM at the first visit to a dietitian for initial or ongoing MNT. The guidelines apply to patients treated with MNT alone, MNT and oral glucose-lowering agents, or MNT and insulin. They provide a framework to assist the dietitian in the assessment, intervention (nutrition prescription, education, goal setting), and evaluation of outcomes for MNT. Minimum referral data for clinical decision making and outcome criteria are defined. Basic nutrition care is defined as one visit with the dietitian. Nutrition practice guidelines care consists of a series of visits with the dietitian. At the second follow-up visit, the dietitian assesses what has been accomplished with the nutrition interventions. If the patient has implemented the nutrition recommendations to the best of his or her ability and has not achieved the treatment goals, the dietitian should notify the physician and recommend that changes in medical management are needed. Ongoing nutrition care is recommended at 6-month to 1-year intervals for both basic and practice guidelines care.
Blood Glucose↗
Effectiveness of medical nutrition therapy provided by dietitians in the management of non-insulin-dependent diabetes mellitus: a randomized, controlled clinical trial.
OBJECTIVE: To assess the effect of medical nutrition therapy (MNT) provided by dietitians on medical and clinical outcomes for adults with non-insulin-dependent diabetes mellitus (NIDDM), and to compare MNT administered according to practice guidelines nutrition care (PGC) to MNT administered with basic nutrition care (BC). DESIGN: A prospective, randomized, controlled clinical trial of two levels of MNT on metabolic control in persons newly diagnosed with or currently under treatment for NIDDM was conducted at diabetes centers in three states (Minnesota, Florida, and Colorado). BC consisted of a single visit with a dietitian; PGC involved an initial visit with a dietitian followed by two visits during the first 6 weeks of the study period. Data were collected at entry to the study and at 3 and 6 months. SUBJECTS: Results are reported for 179 men and women aged 38 to 76 years: 85 assigned randomly to BC and 94 to PGC. This represents 72% of the 247 subjects enrolled. An additional 62 adults with NIDDM at one site who had no contact with a dietitian were identified as a nonrandom comparison group. OUTCOMES: Medical outcome measures included fasting plasma glucose (FPG), glycated hemoglobin (HbA1c), and serum lipid levels. Clinical outcomes included weight, body mass index, waist-to-hip ratio, and changes in medical therapy. STATISTICAL ANALYSES: Initial analysis of the discrete variables was done using the chi 2 statistic with Yates' correction. Initial analysis of continuous variables was done by analysis of variance. The changes in variables between time periods were analyzed by paired t test, and comparisons between groups were analyzed using a t test for independent groups. RESULTS: At 6 months, PGC resulted in significant improvements in blood glucose control as indicated by FPG and HbA1c levels and BC resulted in significant improvements in HbA1c level. Participants assigned to the PGC group had a mean FPG level at 6 months that was 10.5% lower than the level at entry, and those in the BC group had a 5.3% lower value. Among subjects who had diabetes for longer than 6 months, those who received PGC had a significantly better HbA1c level at 3 months compared with those receiving BC. The comparison group showed no improvement in glycemic control over a comparable 6 months. PGC subjects had significant improvements in cholesterol values at 6 months, and subjects in both the PGC and the BC groups had significant weight loss. CONCLUSIONS: MNT provided by dietitians resulted in significant improvements in medical and clinical outcomes in both the BC and PGC groups and is beneficial to persons with NIDDM. Persons with a duration of diabetes longer than 6 months tended to do better with PGC than with BC. Because of the upward trend in glucose levels after 3 months, ongoing MNT by dietitians is important for long-term metabolic control.
Adult↗
Cost-effectiveness of medical nutrition therapy provided by dietitians for persons with non-insulin-dependent diabetes mellitus.
OBJECTIVE: To conduct a cost analysis and cost-effectiveness study based on a randomized clinical trial of basic nutrition care (BC) and practice guidelines nutrition care (PGC) provided by dietitians in outpatient clinics. DESIGN: Subjects with non-insulin-dependent diabetes mellitus (NIDDM) from three states (Minnesota, Florida, Colorado) were randomly assigned to a group receiving BC or a group receiving PGC for a 6-month clinical trial. Along with data about medical and clinical outcomes, data about cost resources were collected. The cost-effectiveness of PGC compared with BC was calculated using per-patient costs and glycemic outcomes for the 6 months of the study. A net cost-effectiveness ratio comparing BC and PGC, including the cost savings resulting from changes in medical therapy, was also calculated. SUBJECTS: The study reports on a sample of 179 subjects with NIDDM between the ages of 38 and 76 years who completed the clinical trial. RESULTS: Patients in the PGC group experienced a mean 1.1 +/- 2.8 mmol/L decrease in fasting plasma glucose level 6 months after entry to the study, for a total per-patient cost of $112. PGC costs included one glycated hemoglobin assay used by the dietitian to evaluate nutrition outcomes. Patients in the BC group experienced a mean 0.4 +/- 2.7 mmol/L decrease, for a total per-patient cost of $42. In the PGC group, 17 persons had changes in therapy, which yielded an average 12-month cost savings prorated for all patients of $31.49. In contrast, in the BC group, 9 persons had changes in therapy, for an average 12-month prorated cost savings of $3.13. Each unit of change in fasting plasma glucose level from entry to the 6-month follow-up can be achieved with an investment of $5.75 by implementing BC or of $5.84 by implementing PGC. If net costs are considered (per-patient costs--cost savings due to therapy changes), the cost-effectiveness ratios become $5.32 for BC and $4.20 for PGC, assuming the medical changes in therapy were maintained for 12 months. APPLICATIONS: These findings suggest that individualized nutrition interventions can be delivered by experienced dietitians with a reasonable investment of resources. Cost-effectiveness is enhanced when dietitians are engaged in active decision making about intervention alternatives based on the patient's needs.
Adult↗