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Biomedical subjects

A M Murray

Publications and source records attributed to A M Murray.

At least 19 recordsLinked to original sources
PubMed2006

Cognitive impairment in hemodialysis patients is common.

BACKGROUND: Hemodialysis patients are at high risk for cognitive impairment due to their older age and high prevalence of stroke and cardiovascular risk factors. METHODS: Using a cross-sectional design, the authors measured cognitive function in 374 hemodialysis patients aged 55 years and older and an age-matched comparison group in Minneapolis and St. Paul, MN. Cognitive performance was measured in three domains: memory, executive function, and language. Subjects were classified as having no, mild, moderate, or severe cognitive impairment. RESULTS: Of 338 subjects who completed testing in at least two of the three cognitive domains, 13.9% (95% CI 10.4, 18.1) were classified with mild impairment, 36.1% (31.0, 41.5) with moderate impairment, 37.3% (32.1, 42.7) with severe impairment, and 12.7% (9.4, 16.8) with normal cognition. Only 2.9% had a documented history of cognitive impairment. Factors associated with severe cognitive impairment on adjusted logistic regression were stroke (adjusted OR [AOR] 1.95; 95% CI 1.08, 3.49; p < 0.03), equilibrated Kt/V > 1.2 (1.67; 1.01, 2.75; p < 0.05), and education >12 years (0.32; 0.14, 0.72; p < 0.01). The AOR for severe cognitive impairment in a random sample of 101 hemodialysis patients vs an age-matched comparison group was 3.54 (1.28, 9.78; p < 0.02). CONCLUSIONS: Moderate to severe cognitive impairment is common and undiagnosed in hemodialysis patients. Further studies are needed to determine whether dialysis exacerbates the cognitive impairment attributable to underlying disease. Cognitive testing in hemodialysis patients before dialysis initiation and periodically may be warranted.

Age Distribution↗
PubMed2005

How to ... place a lower bonded retainer.

Post-orthodontic relapse of lower incisors is a common phenomenon. Sometimes a bonded retainer is fitted to prevent this relapse. In this article, we suggest a handy clinical technique of fitting a lower bonded retainer, which is convenient and easy to carry out.

Acid Etching, Dental↗
PubMed2001

The oldest fossil cichlids (Teleostei: Perciformes): indication of a 45 million-year-old species flock.

Five closely related species of fossil cichlids collected from an Eocene site in Tanzania, East Africa, represent the oldest known cichlids. The specimens are whole-body, articulated fishes that are extremely well preserved and, therefore, have the potential to add to our knowledge of the history of this family. Modern cichlids are particularly well known for the numerous species flocks of the East African Great Lakes. A great deal of research is ongoing regarding all aspects of the fishes in these flocks, including their evolutionary history The new collection of fossils reported here is interpreted as representing a species flock that arose in a small crater lake. These fossils indicate that cichlids' ability to form species flocks evolved early in the history of this family.

Africa, Eastern↗
PubMed2001

Evaluation of a PCR/DNA probe colorimetric membrane assay for identification of Campylobacter spp. in human stool specimens.

DNA was extracted from 50 human stool specimens using the QIAamp DNA stool minikit. PCR amplification was followed by post-PCR hybridization to DNA probes specific for the Campylobacter genus, Campylobacter jejuni, and Campylobacter coli in a colorimetric membrane assay. Thirty-two of 38 culture-positive specimens were PCR/DNA probe positive for C. jejuni. The assay is rapid and simple and can be applied to stool specimens for the detection of Campylobacter.

Campylobacter↗
PubMed2000

For four sixes.

This article reviews the literature on orthodontic treatment involving extraction of first molars and highlights many of the clinical considerations when treating such cases. Case reports illustrate the potential problems and indicate some solutions.

Adolescent↗
PubMed2000

The teaching of occupational and environmental medicine to medical students in Australia and New Zealand.

All the medical schools in Australia and New Zealand were surveyed in order to determine the amount of teaching devoted to occupational and environmental medicine in the medical courses in 1998. A 100% response rate was achieved. The results showed that the number of hours devoted to these topics varied widely, but averaged 12.8 h and 10.5 topics. The most significant factor accounting for the variability was the presence on the universities' teaching staff of individuals trained in the practice of occupational medicine. While our findings show a greater time devoted to these topics than those of similar studies in the United States and Britain, the absolute time remains small when compared with the prevalence of occupational medicine problems in the community. There is little congruence in terms of both content and assessment processes between schools.

Australia↗
PubMed1999

Differential effects of haloperidol and clozapine on ionotropic glutamate receptors in rats.

Despite multiple lines of investigation the effect of neuroleptics on glutamate-mediated neurotransmission remains controversial. To study the effects of typical and atypical neuroleptics on selected parameters of glutamate-mediated neurotransmission, male Sprague-Dawley rats were randomly assigned to a 21-day oral treatment course with vehicle, haloperidol (HDL), or clozapine (CLZ). Coronal slices of rat brain were then incubated with tritiated ligands to measure NMDA, AMPA, and kainate receptor, and glutamate reuptake site density. Regions of interest included the frontal cortex, anterior cingulate cortex, dorsal striatum, ventral striatum, and the nucleus accumbens. CLZ increased the density of AMPA receptors significantly in the frontal and anterior cingulate cortices compared with normal controls. In the dorsal and ventral striatum, and nucleus accumbens as a whole, CLZ-treated rats had a higher AMPA receptor density compared with both the HDL- and vehicle-treated controls. Additionally, within the nucleus accumbens, CLZ-treated rats had a higher density of AMPA receptors compared with the HDL group in the core, and at trend level in the shell. There was a group by region interaction for NMDA receptor density, primarily reflecting the tendency of HDL treated rats to have high receptor densities in the frontal and anterior cingulate cortices. Kainate receptors and glutamate reuptake site densities did not differ significantly across groups. These results suggest a critical role for glutamate in the mediation of atypical antipsychotic drug action in anatomically-specific regions, and further encourage the investigation of glutamate neurotransmitter systems in schizophrenia.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1999

Acyltransferase activities in the yolk sac membrane of the chick embryo.

The activities of some enzymes of glycerolipid synthesis and fatty acid oxidation were measured in subcellular fractions of the yolk sac membrane (YSM), an extra-embryonic tissue that mediates the transfer of lipid from the yolk to the circulation of the chick embryo. The activities of monoacylglycerol acyltransferase and carnitine palmitoyl transferase-1 in the YSM (respectively, 284.8+/-13.2 nmol/min/mg microsomal protein and 145.6+/-9.1 nmol/min/mg mitochondrial protein; mean +/- SE; n = 4) at day 12 of development appear to be the highest yet reported for any animal tissue. Also, the carnitine palmitoyl transferase-1 of the YSM was very insensitive to inhibition by malonyl CoA. The maximal activities of glycerol-3-phosphate acyltransferase and diacylglycerol acyltransferase in the YSM (respectively, 26.7+/-2.2 and 36.1+/-2.1 nmol/min/mg microsomal protein) were also high compared with the reported values for various animal tissues. The very high enzymic capacity for glycerolipid synthesis supports the hypothesis that the yolk-derived lipids are subjected to hydrolysis followed by reesterification during transit across the YSM. The monoacylglycerol pathway appears to be the main route for glycerolipid resynthesis in the YSM. The results also suggest that the YSM has the capacity to perform simultaneously beta-oxidation at a high rate in order to provide energy for the lipid transfer process.

Acyltransferases↗
PubMed1999

Piggyback archwires.

Commonly, clinicians' principal tool in the alignment phase of orthodontic mechanotherapy is the nickel-titanium wire. During the course of orthodontic treatment, however, there are times when some segments of the dental arch require flexible wires, while the rest would benefit from rigid wires. In this report, we describe a technique where both of these needs are satisfied simultaneously. Specifically, a segment of nickel-titanium wire is piggybacked onto a stainless steel wire in regions where flexibility is desired. This method eliminates the problems associated with the activation, de-activation forces created along a continuous archwire and might be more economical. Clinical pictures illustrate the point.

Adolescent↗
PubMed1998

Production of glutathione-coated microtitre plates for capturing recombinant glutathione S-transferase fusion proteins as antigens in immunoassays.

Glutathione S-transferase (GST) is commonly used as a fusion partner in producing recombinant proteins and this technology is increasingly being used to produce antigens for use in immunoassays to measure antibodies. To circumvent the requirement to purify such antigens before use, we developed a method for coupling glutathione to microtitre plates so that GST-containing recombinant proteins could be purified and immobilised in one step in a suitable state for immunoassays. This procedure involves covalent linkage (using the heterobifunctional cross-linker sulphosuccinimidyl 4-(p-maleimidophenyl)butyrate) of reduced glutathione through its sulphydryl group to lysine residues of haemoglobin previously immobilised on microtitre plates. Haemoglobin was superior over other proteins tested in giving the lowest non-specific binding; in this regard it was also important to limit the amount of cross-linker used to 0.1 mM. Using glutamic acid decarboxylase as a model antigen, the new affinity capture assay was at least as good as the two-step procedure involving direct adsorption to plates of previously purified antigen; it may have the additional advantage of preserving the antigen in a more native conformation than direct adsorption. The new assay also performed as well as an assay using anti-GST antibodies adsorbed onto plates; glutathione plates, unlike anti-GST plates, will only capture recombinant proteins containing functional GST--a significant point for some recombinant expression systems in which a large proportion of the protein product is insoluble because of incorrect folding.

Autoantibodies↗
PubMed1998

Cytokine gene expression in murine fetal intestine: potential for extrathymic T cell development.

An increasing body of evidence suggests that certain T cell subsets mature extrathymically in the epithelium of the intestine. In the studies reported here, the authors have analysed cytokine/growth factor gene expression, recombinase-activating gene RAG-1 and RAG-2 gene expression and terminal deoxynucleotidyl transferase (TdT) gene expression in mouse fetal intestine and fetal thymus and liver, two known haematopoietic tissues. Stem cell factor (SCF) and interleukin 7 (IL-7) message was abundant in all three tissues during fetal development. IL-2 and IL-4 were not expressed in fetal gut but IL-4 was weakly detected in fetal liver and thymus. IL-9 and IL-13 mRNA was detected in all fetal tissues and IL-15 mRNA was abundant in fetal intestine but only weakly expressed in fetal liver and thymus. mRNA for SCF, IL-7, IL-13 and IL-15 was also detected in fibroblast-like cell lines derived from fetal intestine. RAG-1 and RAG-2 mRNA was detected in all three fetal tissues. TdT mRNA was not detected in fetal gut or liver but was weakly expressed in (fetal day) fd19-20 fetal thymus. Long-term (> 6 weeks) in vitro growth of IEL was achieved by coculturing intraepithelial lymphocytes (IEL) with IL-7-secreting fibroblasts in the presence of SCF and IL-2. The data show that the fetal mouse gut provides a suitable environment for lymphocyte development and receptor rearrangement, similar to fetal thymus and liver, even though expansion of intestinal IEL is delayed until 2-3 weeks after birth.

Animals↗
PubMed1998

Loss of dopamine D2 receptors in Alzheimer's disease with parkinsonism but not Parkinson's or Alzheimer's disease.

A significant proportion of patients with Alzheimer's disease (AD) exhibit extrapyramidal features that are referred to as parkinsonism (AD/Park) to distinguish the clinical and pathological features that differ from Parkinson's disease (PD). Previous results from this laboratory have shown that, although the presynaptic components of the dopamine (DA) system are markedly affected in AD/Park, the pathology is not similar to PD (Murray et al. 1995; Joyce et al. 1997). In the present study, we determined whether the parkinsonian symptoms in AD/Park might also reflect changes in numbers of postsynaptic DA receptors. We analyzed the binding of [125I]epidepride biding to DA D2/D3 receptors and [3H]SCH 23390 to D1 receptors by autoradiography in the striatum of six patients with PD, nine patients with AD, seven patients with AD/Park, and 14 neurologically intact control subjects. D2 receptors were reduced in the caudate and putamen of the AD/Park group (by 42 and 27% of controls, respectively) but not reduced in AD or PD. D1 receptors were elevated by 36% in the putamen of the PD group. Dopamine receptor changes are, therefore, not similar in PD, AD, and AD/Park. The elevation in D1 receptors in PD may contribute to the unwanted side effects of L-dopa treatment. The loss of D2 receptors in AD/Park, not observed in AD lacking overt parkinsonian symptomatology, may contribute to the presence of parkinsonian features and lack of responsiveness to L-dopa.

Aged↗
PubMed1998

Intestinal IgA plasma cells of the B1 lineage are IL-5 dependent.

Two lineages of B cells, designated B1 and B2 cells, have been identified based upon their origins, anatomical distribution, cell surface markers, antibody repertoire and self-replenishing potential. B1 cells are maintained by self-renewal of cells resident in the peritoneal cavity (PerC) and they utilize a limited repertoire of germline V-region genes, mostly directed against ubiquitous bacterial antigens such as phosphoryl choline (PC). B2 cells are replenished from bone marrow precursors and use a larger repertoire of immunoglobulin V-region genes. Whereas most immunoglobulin A (IgA) plasma cells in the intestine derive from B2 lineage precursors in the Peyer's patch, a subpopulation of Per C-derived B1 cells populate the intestinal lamina propria where they mature into IgA plasma cells. In previous in vivo studies we have shown that whereas IgA+ B2 cells are interleukin (IL)-6 dependent, B1 cells are IL-6 independent. In view of the in vitro evidence that IL-5 is also involved in IgA expression, in the studies reported here we have used IL-5-deficient mice to evaluate the role of IL-5 in vivo in IgA expression in the gut. The results demonstrate that although total IgA cell numbers are only marginally depressed in IL-5-deficient mice, there is a marked selective depletion of IgA+ cells of the B1 lineage in the gut and a corresponding depression in the capacity of these mice to mount an intestinal response to a B1 antigen (PC) but not to a B2 antigen (oralbumin; OVA), reflecting intact B2-derived IgA cell function but a defect in the B1 cell contribution to IgA responses in IL-5 deficient mice. Collectively these data demonstrate differential cytokine regulation of subsets of IgA+ cells in the gut in that IgA+ cells of the B2 lineage are IL-6 dependent but IL-5 independent, but B1-derived IgA+ cells are IL-5 dependent and IL-6 independent.

Animals↗
PubMed1996

A postmortem study of frontal cortical dopamine D1 receptors in schizophrenics, psychiatric controls, and normal controls.

We tested the hypothesis that aberrant dopaminergic innervation in frontal and cingulate cortices of schizophrenic patients might be revealed by examining dopamine D1 receptor density in these brain regions. A quantitative autoradiographic assay with [3H]-SCH 23390 was performed with samples from schizophrenic patients, normal controls, neuroleptic-treated controls, and suicides. There was a significant elevation in specific binding of [3H]-SCH 23390 in the intermediate layer of the prefrontal cortex from neuroleptic-treated controls (p = .05). Elevated [3H]-SCH 23390 binding in several layers from prefrontal and cingulate cortex was observed in schizophrenic subjects, although these results did not reach statistical significance. When data from subjects who had received neuroleptics (schizophrenics and neuroleptic controls) were compared to subjects who had not received neuroleptics (normal controls and suicides), there was a significant elevation in receptor density in both the prefrontal (p = .05) and cingulate cortices (p = .03). These data suggest that elevated [3H]-SCH 23390 binding in human prefrontal and cingulate cortices may occur with chronic neuroleptic treatment, although increased receptor density that may exist as a feature of psychotic illnesses cannot be excluded.

Autoradiography↗
PubMed1996

Prevalence of parkinsonian signs and associated mortality in a community population of older people.

BACKGROUND: Older people frequently have signs of parkinsonism, but information about the prevalence of parkinsonism and mortality among those with the condition in the community is limited. METHODS: A stratified random sample of 467 residents of East Boston, Massachusetts, 65 years of age or older, were given structured neurologic examinations. Using uniform, specified combinations of parkinsonian signs, we estimated the prevalence of four categories of signs--bradykinesia, gait disturbance, rigidity, and tremor--and of parkinsonism, defined as the presence of two or more categories. We did not study Parkinson's disease because it could not be distinguished from other conditions that can cause parkinsonism. Proportional-hazards models were used to compare the risk of death among people with and those without parkinsonism. RESULTS: One hundred fifty-nine persons had parkinsonism, 301 did not, and 7 could not be classified. The overall prevalence estimates were 14.9 percent for people 65 to 74 years of age, 29.5 percent for those 75 to 84, and 52.4 percent for those 85 and older. With a mean follow-up period of 9.2 years, 124 persons with parkinsonism (78 percent) and 146 persons without (49 percent) died. Adjusted for age and sex, the overall risk of death among people with parkinsonism was 2.0 (95 percent confidence interval, 1.6 to 2.6) times that among people without. Among people with parkinsonism, the presence of gait disturbance was associated with an increased risk of death. CONCLUSIONS: Parkinsonism is very common among people over the age of 65, and its prevalence increases markedly with age. Parkinsonism is associated with a twofold increase in the risk of death, which is strongly related to the presence of a gait disturbance.

Age Distribution↗