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Biomedical subjects

R Nichols

Publications and source records attributed to R Nichols.

At least 55 records · Page 3Linked to original sources
PubMed1997

Complications and concurrent disease associated with canine hyperadrenocorticism.

In untreated hyperadrenocorticism, clinical problems may result from metastasis of an adrenocortical carcinoma, growth of a pituitary tumor, or complications associated with sustained hypercortisolemia itself, such as hypertension, cardiovascular disease, thromboembolism, glucose intolerance, and increased susceptibility to infection. This article discusses the origin, diagnosis, and treatment of the many complications associated with hyperadrenocorticism.

Adrenal Cortex Diseases↗
PubMed1997

Multiple antigenic peptides designed to structurally related Drosophila peptides.

We have isolated TDVDHVFLRFamide (DMS), FDDYGHMRFamide (DSK), and DPKQDFMRFamide from Drosophila melanogaster. These peptides, structurally related by a common C-terminus -XRFamide, where X = L or M, are encoded by three different genes. To determine cellular expression, we have generated antisera to multiple antigenic peptides and performed double-label immunofluorescence using antisera raised in the same species host animal. Our results indicate that DMS and DSK immunoreactive materials have unique, non-overlapping expression patterns, while DMS and DPKQDFMRFamide immunoreactive materials colocalize in two superior protocerebrum neurons, and DSK and DPKQDFMRFamide immunoreactive materials colocalize in one superior protocerebrum neuron, one subesophageal ganglion neuron, and three thoracic ganglia neurons.

Animals↗
PubMed1997

Complications and concurrent disease associated with diabetes mellitus.

Many animals with diabetes mellitus are severely ill on clinical presentation. The spectrum of disease is quite variable and includes diabetic ketoacidosis (DKA), ketosis without acidosis, hyperosmolar nonketotic syndrome (HNKS), and other nonketotic variants (negative urine ketones, serum osmolality < 340 mOsm/kg with or without acidosis). These more severe forms of diabetes are often precipitated by concurrent diseases such as pyelonephritis, pancreatitis, pyometra, hyperadrenocorticism, renal failure, and heart failure. To make matters worse, in-hospital treatment of diabetic dogs and cats is commonly associated with serious complications, including hypoglycemia, hypokalemia, and hypophosphatemia.

Animals↗
PubMed1997

Who are the 'low energy reporters' in the dietary and nutritional survey of British adults?

BACKGROUND: Underreportin in dietary surveys is a potential source of bias in studies of diet and disease. The aim of this study was to identify characteristics of men and women participants in the Dietary and Nutritional Survey of British Adults (DNSBA) who stated that they were neither slimming nor ill, and who reported an average energy intake over a 7-day period below 1.2 times estimated basal metabolic rate (BMR), termed here 'low energy reporters' (LER). METHODS: In all, 2197 men and women aged 16-64 years participated in the DNSBA. Dietary intake was assessed using the 7-day weighed intake method. Their BMR was estimated using predictive equations based upon age, sex and body weight. RESULTS: Compared with non-LER, LER had higher mean ratios of urinary urea nitrogen to dietary nitrogen and urinary potassium to dietary potassium, indicating that, as a group, LER were underreporting at least for protein and potassium intakes. Overall LER were overrepresented among the manual social classes, smokers, and self-reported non-alcohol drinkers, and were on average heavier than non-LER. There was indication of differential reporting of foods and differences in macronutrient and micronutrient densities between LER and non-LER. CONCLUSION: These results suggest that LER may be overrepresented within specific population subgroups and that underreporting bias may not be food and nutrient neutral. This has implications for the design and interpretation of studies of diet and disease.

Adolescent↗
PubMed1996

Inverse relation of dietary protein markers with blood pressure. Findings for 10,020 men and women in the INTERSALT Study. INTERSALT Cooperative Research Group. INTERnational study of SALT and blood pressure.

BACKGROUND: The purpose of this study was to assess relations to blood pressure (BP) in individuals of markers of dietary protein in their 24-hour urine collections. METHODS AND RESULTS: INTERSALT (INTERnational study of SALT and blood pressure) was a cross-sectional study of 10020 men and women aged 20 to 59 years in 52 population-based samples in 32 countries worldwide, with quality-controlled standardized procedures and assessment of multiple possible confounders. Three measurements of dietary protein in 24-hour urine of each individual participant were studied: total nitrogen and urea as indexes of total protein intake, and sulfate as an index of sulfur-containing dietary amino acids. Repeat examination was performed in a random 8% of participants to assess reliability and to correct for regression-dilution bias. Significant independent inverse relationships were found between BP (systolic and diastolic) and both 24-hour urinary total nitrogen and urea nitrogen, with adjustment for age, sex, alcohol intake, body mass, and 24-hour urinary sodium, potassium, calcium, and magnesium. With adjustment for regression-dilution bias, it was estimated that systolic and diastolic BP were on average 3.0 and 2.5 mm Hg lower, respectively, for persons with dietary total protein intake 30% above the overall mean than for those whose dietary protein intake was 30% below the overall mean (12.94 versus 6.96 g/d urinary total nitrogen, equivalent to 81 versus 44 g/d dietary protein, respectively). For the association of these markers with diastolic BP, results were similar for younger (20- to 39-year-old) and older (40- to 59-year-old) persons and for women and men. For their relation to systolic BP, regression coefficients were larger both for those aged 40 to 59 years than for those aged 20 to 39 years and for women than for men. Nonsignificant inverse relations were recorded for urinary sulfate and BP. CONCLUSIONS: These INTERSALT findings lend support to the hypothesis that higher dietary protein intake has favorable influences on BP.

Adult↗
PubMed1996

Intersalt revisited: further analyses of 24 hour sodium excretion and blood pressure within and across populations. Intersalt Cooperative Research Group.

OBJECTIVES: To assess further the relation in Intersalt of 24 hour urinary sodium to blood pressure of individuals and populations, and the difference in blood pressure from young adulthood into middle age. DESIGN: Standardised cross sectional study within and across populations. SETTING: 52 population samples in 32 countries. SUBJECTS: 10,074 men and women aged 20-59. MAIN OUTCOME MEASURES: Association of sodium and blood pressure from within population and cross population multiple linear regression analyses with multivariate correction for regression dilution bias. Relation of sample median daily urinary sodium excretion to difference in blood pressure with age. RESULTS: In within population analyses (n = 10,074), individual 24 hour urinary sodium excretion higher by 100 mmol (for example, 170 v 70 mmol) was associated with systolic/diastolic blood pressure higher on average by 3/0 to 6/3 mm Hg (with and without body mass in analyses). Associations were larger at ages 40-59. In cross population analyses (n = 52), sample median 24 hour sodium excretion higher by 100 mmol was associated with median systolic/diastolic pressure higher on average by 5-7/2-4 mm Hg, and estimated mean difference in systolic/diastolic pressure at age 55 compared with age 25 greater by 10-11/6 mm Hg. CONCLUSIONS: The strong, positive association of urinary sodium with systolic pressure of individuals concurs with Intersalt cross population findings and results of other studies. Higher urinary sodium is also associated with substantially greater differences in blood pressure in middle age compared with young adulthood. These results support recommendations for reduction of high salt intake in populations for prevention and control of adverse blood pressure levels.

Adult↗
PubMed1996

Spatial and temporal immunocytochemical analysis of drosulfakinin (Dsk) gene products in the Drosophila melanogaster central nervous system.

The spatial and temporal distribution of three peptides, DSK I, DSK II, and DSK 0, encoded by the Drosophila melanogaster drosulfakinin (Dsk) gene, have been examined in the central nervous system. DSK I and DSK II have a -RFamide C-terminus and are structurally similar to sulfakinin peptides; in contrast, DSK 0 contains -SFamide and is not structurally similar to sulfakinins. Antisera specificities were determined by the design of the antigens and confirmed by dot blot analysis and preincubation with peptides prior to their use in immunocytochemistry. The distribution of immunoreactivity suggests that all three DSK peptides are processed from the polypeptide precursor and expressed in many of the same cells. Expression was observed at all developmental stages with an increase in the level of staining and the number of immunoreactive cells as development progresses. Cells in the brain lobe, optic lobe, subesophageal ganglion, thoracic ganglia, and the eighth abdominal neuromere contain DSK-immunoreactive materials. Immunoreactive fibers project from some cells and extend into the brain and ventral ganglion with regions of extensive arborization. DSK 0 immunoreactivity provides initial evidence for the presence of a -SFamide peptide in neural tissue. The observed expression of DSK-immunoreactive materials throughout development in numerous cells of the central nervous system suggests that DSK peptides may serve as hormones, modulators, or transmitters involved in several functions.

Amino Acid Sequence↗
PubMed1996

Dietary salt, nitrate and stomach cancer mortality in 24 countries. European Cancer Prevention (ECP) and the INTERSALT Cooperative Research Group.

BACKGROUND: High salt and nitrate intake are considered as risk factors for stomach cancer, but little is known about possible interactions. This ecological study examines the respective importance of both factors for stomach cancer mortality at the population level using data obtained under standardized conditions and with biochemical analyses performed in the same laboratories. METHODS: Randomly selected 24-hour urine samples from 39 populations, sampled from 24 countries (N = 5756 people for sodium, 3303 for nitrate) were obtained from the INTERSALT study. Median sodium and nitrate levels were age- and sex-standardized between ages 20-49 years and averaged per country. Ecological correlation-regression analyses were done in relation to national stomach cancer mortality rates. RESULTS: The Pearson correlation of stomach cancer mortality with sodium for the 24 countries was: 0.70 in men and 0.74 in women (both P < 0.001) and with nitrate: 0.63 (P = 0.001) in men and (P < 0.005) in women. In multiple regression of stomach cancer mortality, using sodium and nitrate as independent variables the adjusted R2 was 0.61 in men and 0.54 in women (both P < 0.001). Addition of the interaction term (sodium x nitrate) to the previous model increased the adjusted R2 to 0.77 in men, and to 0.63 in women. The analysis of this model showed that the importance of nitrate as risk factor for stomach cancer mortality increased markedly with higher sodium levels. However, the relationship of stomach cancer mortality with sodium was always stronger than with nitrate. CONCLUSIONS: Salt intake, measured as 24-hour urine sodium excretion, is likely the rate-limiting factor of stomach cancer mortality at the population level.

Adult↗
PubMed1996

Twenty-four hour urinary nitrate excretion in 48 populations from 30 countries: an ECP-INTERSALT collaborative study.

BACKGROUND: There is considerable interest in the possible role of nitrate in gastric carcinogenesis, but little information on nitrate intake around the world. This is the first study to give comprehensive standardised data on nitrate excretion as a marker of intake, using 48 worldwide population samples. METHODS: Urinary nitrate excretion has been shown to be a valid measure of nitrate intake in people under 50. This report presents data on 24-hour urinary nitrate excretion from urine collections obtained in the INTERSALT study, based on random samples of men and women aged 20-49 from each of 48 population samples in 30 countries. RESULTS: There was large variation in urinary nitrate excretion both within and between samples; within-sample (individual) distributions tended to be skewed towards higher values. Median values of the samples ranged from 0.42 mmol/day (Labrador, Canada) to 3.52 (Beijing, People's Republic of China) in men and 0.44 mmol/day (Colombia) to 3.44 (Beijing) in women. Overall, median values were higher in men than women by 11% on average (higher in men in 37 of 48 population samples). Comparison by geographical region of median values for men and women combined showed relatively low values in the samples in North America and Northern Europe (range 0.46-0.88 mmol/day), slightly higher values in Western Europe and Africa (0.68-1.11), and intermediate to high values in Southern Europe, Eastern and Central Europe and India (0.86-2.47). The highest median values were found in the Far Eastern samples (up to 3.48). Median values in the Central and South American samples ranged from 0.48 mmol/day (Colombia) to 1.37 (Xingu Indians of Brazil, and Argentina). CONCLUSIONS: For the first time, these data give standardized information on urinary nitrate excretion from different geographical regions of the world, and provide a basis for the further exploration of the role of nitrate in the aetiology of disease in human populations.

Adult↗
PubMed1996

Localization of myosuppressinlike peptides in the hypocerebral ganglion of two blood-feeding flies: horn fly and stable fly (Diptera:Muscidae).

The insect peptides leucomyosuppressin (pEDVDHVFLRFamide) and dromyosuppressin (TDVDHVFLRFamide) have identical chemical sequences with the exception of the N-terminal amino acid; both inhibit spontaneous contraction of insect visceral muscles. Neurons in the hypocerebral ganglion of horn fly, Hematobia irritans (L.), and stable fly, Stomoxys calcitrans (L.), were found to contain material immunoreactive to antiserum produced against the C-terminal of leucomyosuppressin, but not to the N-terminal of dromyossuppressin. Two large lateral clusters containing 8 cells, linked dorsally and ventrally by 2 chains of 6 cells, encircled the anterior surface of the proventriculus and were immunoreactive of leucomyosuppressin and FMRFamide antisera. Axons from these cells were traced to the wall of the aorta and over the surface of the proventriculus. Ultrastructural analysis revealed these cells contained a singular type of elementary secretory granule that contained material of relatively low electron density, both in the cell body and at the axon terminals.

Animals↗
PubMed1996

Cultural issues in death and dying.

Although all of us experience death, not all of us think about death or respond to death the same way. This study begins to explore how cultural traditions, education, and tenure in Hawaii impact views of advanced directives, organ donation, suicide, and euthanasia. This information is useful to physicians who need to engage patients and families in discussions about death and end-of-life decision making.

Asian↗
PubMed1995

Human alanyl-tRNA synthetase: conservation in evolution of catalytic core and microhelix recognition.

The class II Escherichia coli and human alanyl-tRNA synthetases cross-acylate their respective tRNAs and require, for aminoacylation, an acceptor helix G3:U70 base pair that is conserved in evolution. We report here the primary structure and expression in the yeast Pichia of an active human alanyl-tRNA synthetase. The N-terminal 498 amino acids of the 968-residue polypeptide have substantial (41%) identity with the E. coli protein. A closely related region encompasses the class-defining domain of the E. coli enzyme and includes the part needed for recognition of the acceptor helix. As a result, previously reported mutagenesis, modeling, domain organization, and biochemical characterization on the E. coli protein appear valid as a template for the human protein. In particular, we show that both the E. coli enzyme and the human enzyme purified from Pichia aminoacylate 9-base pair RNA duplexes whose sequences are based on the acceptor stems of either E. coli or human alanine tRNAs. In contrast, the sequences of the two enzymes completely diverge in an internal portion of the C-terminal half that is essential for tetramer formation by the E. coli enzyme, but that is dispensable for microhelix aminoacylation. This divergence correlates with the expressed human enzyme behaving as a monomer. Thus, the region of close sequence similarity may be a consequence of strong selective pressure to conserve the acceptor helix G3:U70 base pair as an RNA signal for alanine.

Alanine-tRNA Ligase↗
PubMed1995

Cellular expression of the Drosophila melanogaster FMRFamide neuropeptide gene product DPKQDFMRFamide. Evidence for differential processing of the FMRFamide polypeptide precursor.

DPKQDFMRFamide is one of five different FMRFamide-containing peptides encoded in the Drosophila FMRFamide gene. To study the cellular expression of DPKQDFMRFamide, we have generated antisera to DPKQD, the N-terminal sequence of the peptide, to avoid crossreactivity with other -FMRFamide-containing peptides. The antisera were purified and the specificity characterized. DPKQDFMRFamide immunoreactive material is first observed in the embryonic central nervous system (CNS) in one cell of the subesophageal ganglion and one cell in each of the three thoracic ganglia. This pattern of expression is observed in larval, pupal, and adult neural tissue, albeit with increased signal intensity. In larva, pupa, and adult, additional cells in the superior protocerebrum, a thoracic ganglion, and an abdominal ganglion express DPKQDFMRFamide immunoreactive material. Immunoreactivity is observed in a cell in the lateral protocerebrum of pupa and adult and cells in the optic lobe of adult. No immunoreactive material was observed in gut tissue. DPKQDFMRFamide antisera stain a subset of cells previously identified by in situ hybridization and immunocytochemistry to express the FMRFamide transcript and polypeptide precursor. These data suggest that the Drosophila FMRFamide polypeptide precursor undergoes differential processing to produce DPKQDFMRFamide immunoreactive material in a limited number of cells expressing the FMRFamide precursor.

Amino Acid Sequence↗
PubMed1995

Spatial and temporal analysis of the Drosophila FMRFamide neuropeptide gene product SDNFMRFamide: evidence for a restricted expression pattern.

The expression of SDNFMRFamide, one of five different FMRFamide-containing peptides encoded by the Drosophila melanogaster FMRFamide gene, has been determined. To study expression, we generated antisera to the N-terminus of SDNFMRFamide to avoid crossreactivity with FMRFamide-containing peptides. The antisera were purified and the specificity characterized. SDNFMRFamide immunoreactive material is present in the central nervous system throughout development. Immunoreactivity is first observed in embryonic neural tissue in a cluster of cells in the subesophageal ganglion and immunoreactive fibers projecting from these cells to the brain and ventral ganglion. This pattern of expression is also observed in neural tissue dissected from larva, pupa, and adult. Double-labelling experiments indicate that cells recognized by SDNFM-antisera are also stained with FMRFamide antisera. Based on position, SDNFMRFamide immunoreactive material is expressed in a limited number of cells that contain the FMRFamide polypeptide precursor. This finding suggests that the Drosophila FMRFamide precursor undergoes differential post-translational processing.

Amino Acid Sequence↗
PubMed1995

Complications and concurrent disease associated with diabetic ketoacidosis and other severe forms of diabetes mellitus.

The more serious forms of diabetes mellitus such as diabetic ketoacidosis (DKA) and hyperosmolar nonketotic syndrome (HNKS) are precipitated commonly by other underlying disease processes. In addition, the treatment of these severe forms of diabetes mellitus are often complicated by therapy. This article discusses common concurrent disorders and therapeutic complications seen in both canine and feline diabetes mellitus.

Animals↗
PubMed1995

Comparison of the activity of meropenem with that of other agents in the treatment of intraabdominal, obstetric/gynecologic, and skin and soft tissue.

Meropenem, a new carbapenem with improved stability in the presence of human dehydropeptidase-I[1], was evaluated in three prospective, multicenter, randomized, controlled clinical trials in North America. We compared the in vitro activity of meropenem and conventional antimicrobial agents for the treatment of intraabdominal, obstetric/gynecologic, and skin or soft tissue infections as well as the responses of pathogens to all of these agents. The trials of the drug for intraabdominal infection were double blind, and those for the obstetric/gynecologic and soft tissue infections were open labeled. Overall, MICs of meropenem for pathogens were lower, and the pathogen response rates were at least comparable to those for the following comparative agents: clindamycin plus tobramycin (for intraabdominal infections); clindamycin plus gentamicin (for obstetric/gynecologic infections); and imipenem and cilastatin (for skin or soft tissue infections). Meropenem has high in vitro potency and covers a broad spectrum of anaerobic and aerobic pathogens.

Abdomen↗