Search PubMed⌕ Search

Biomedical subjects

R A Anderson

Publications and source records attributed to R A Anderson.

At least 181 records · Page 10Linked to original sources
PubMed1995

Acute exercise effects on urinary losses and serum concentrations of copper and zinc of moderately trained and untrained men consuming a controlled diet.

Acute exercise effect on urinary losses and serum concentrations of Cu and Zn of eight moderately trained and five untrained male runners were determined to ascertain effects of training on trace metal responses owing to acute exercise. Maximum oxygen uptake (VO2 max) of the moderately trained subjects was 47.3 +/- 2.3 and that of the untrained subjects was 34.7 +/- 1.9 ml kg-1 min-1. Subjects consumed a controlled diet to minimize changes due to dietary intake. Immediately following acute exercise at 90% of VO2 max to exhaustion (30 s exercise and 30 s rest periods), serum Zn and Cu levels of moderately trained and untrained subjects were elevated. Serum Zn of moderately trained subjects 2 h post-exercise was lower than before exercise (13.5 +/- 0.05 versus 12.5 +/- 0.05 mumol 1-1, a similar trend was observed for untrained subjects. Serum concentrations of both groups were similar to pre-exercise levels 2 h post-exercise. Changes in urinary losses of Zn and Cu, associated with the acute strenuous exercise of short duration employed in this study, were not significantly different. These data demonstrate that increases in serum Cu and Zn following acute exercise are independent of training status for moderately trained and untrained men.

Copper↗
PubMed1995

A phosphatidylinositol 4,5-bisphosphate-sensitive casein kinase I alpha associates with synaptic vesicles and phosphorylates a subset of vesicle proteins.

In interphase cells, alpha-casein kinase I (alpha-CKI) is found associated with cytosolic vesicular structures, the centrosome, and within the nucleus. To identify the specific vesicular structures with which alpha-CKI is associated, established cell lines and primary rat neurons were immunofluorescently labeled with an antibody raised to alpha-CKI. In nonneuronal cells, alpha-CKI colocalizes with vesicular structures which align with microtubules and are partially coincident with both Golgi and endoplasmic reticulum markers. In neurons, alpha-CKI colocalizes with synaptic vesicle markers. When synaptic vesicles were purified from rat brain, they were highly enriched in a CKI, based on activity and immunoreactivity. The synaptic vesicle-associated CKI is an extrinsic kinase and was eluted from synaptic vesicles and purified. This purified CKI has properties most similar to alpha-CKI. When the activities of casein kinase I or II were specifically inhibited on isolated synaptic vesicles, CKI was shown to phosphorylate a specific subset of vesicle proteins, one of which was identified as the synaptic vesicle-specific protein SV2. As with alpha-CKI, the synaptic vesicle CKI is inhibited by phosphatidylinositol 4,5-bisphosphate (PIP2). However, synthesis of PIP2 was detected only in plasma membrane-containing fractions. Therefore, PIP2 may spatially regulate CKI. Since PIP2 synthesis is required for secretion, this inhibition of CKI may be important for the regulation of secretion.

Animals↗
PubMed1995

Novel PI(4)P 5-kinase homologue, Fab1p, essential for normal vacuole function and morphology in yeast.

The FAB1 gene of budding yeast is predicted to encode a protein of 257 kDa that exhibits significant sequence homology to a human type II PI(4)P 5-kinase (PIP5K-II). The recently cloned human PIP5K-II specifically converts PI(4)P to PI(4,5)P2 (Boronenkov and Anderson, 1995). The region of highest similarity between Fab1p and PIP5K-II includes a predicted nucleotide binding motif, which is likely to correspond to the catalytic domain of the protein. Interestingly, neither PIP5K-II nor Fab1p exhibit significant homology with cloned PI 3-kinases or PI 4-kinases. fab1 mutations result in the formation of aploid and binucleate cells (hence the name FAB). In addition, loss of Fab1p function causes defects in vacuole function and morphology, cell surface integrity, and cell growth. Experiments with a temperature conditional fab1 mutant revealed that their vacuoles rapidly (within 30 min) enlarge to more than double the size upon shifting cells to the nonpermissive temperature. Additional experiments with the fab1 ts mutant together with results obtained with fab1 vps (vacuolar protein sorting defective) double mutants indicate that the nuclear division and cell surface integrity defects observed in fab1 mutants are secondary to the vacuole morphology defects. Based on these data, we propose that Fab1p is a PI(4)P 5-kinase and that the product of the Fab1p reaction, PIP2, functions as an important regulator of vacuole homeostasis perhaps by controlling membrane flux to and/or from the vacuole. Furthermore, a comparison of the phenotypes of fab1 mutants and other yeast mutants affecting PI metabolism suggests that phosphoinositides may serve as general regulators of several different membrane trafficking pathways.

Amino Acid Sequence↗
PubMed1995

Field evidence for multiple host contacts during blood feeding by Culex tarsalis, Cx. restuans, and Cx. nigripalpus (Diptera: Culicidae).

Field studies were conducted in Manitoba, Canada, and Florida, United States to evaluate the frequency of multiple host contacts by Culex tarsalis Coquillett, Cx. restuans Theobald, and Cx. nigripalpus Theobald, primary and secondary vectors of several encephalitis viruses in North America. Blood-fed mosquitoes were collected from box traps, each baited with a pair of quail. One quail of each pair was injected with rubidium and the other with cesium to permit the determination of the source(s) of each blood meal. Approximately 5% of all blood-fed Cx. tarsalis, Cx. restuans, and Cx. nigripalpus ingested blood from both quail during overnight exposure. The frequency of multiple feeding by these species ranged from 0 to 18.5%, 0 to 33.3%, and 0 to 17.6%, respectively. Of the 331 mosquitoes that ingested blood from 2 quail, 57 (17.2%) were not fully blood fed. Also, 1.0-3.5% of blood-fed mosquitoes had ingested blood before entering the quail-baited traps. Any increase in the number of host contacts as a result of multiple feeding, however modest, may increase disproportionately the rate at which virus transmission occurs.

Animals↗
PubMed1995

Purification and partial characterization of acrosome reaction inhibiting glycoprotein from human seminal plasma.

The human acrosome reaction (AR; sperm exocytosis) is absolutely required for fertilization. In the course of further characterizing the AR and its control, an AR-inhibiting glycoprotein (ARIG) from human seminal plasma was purified by differential centrifugation, carboxymethyl cellulose chromatography, chromatofocusing, and Sephacryl S300 gel filtration. A highly purified protein with a molecular weight of 74,000 was obtained as determined by gel filtration and SDS-PAGE. ARIG eluted in a narrow pH range (6.2-5.4) during chromatofocusing, corresponding to a pl of 5.8 +/- 0.4. It had covalent modifications, including internal disulfide bonds, and both complex N-linked and O-linked oligosaccharide chains. Lectin analysis suggested that sialic acid was absent and that the complex oligosaccharide chains had sequences containing galactose, galactosamine, and/or glucosamine in a beta 1-4 linkage. Mannose residues were also present. When ARIG was added to in vitro-capacitated human spermatozoa 30 min prior to the calcium ionophore A23187, the AR was significantly inhibited (ID50 = 8.5 micrograms/ml). In addition, ARIG reduced sperm exocytosis in response to atrial natriuretic peptide (a guanylate cyclase activator) and to the protein kinase C activators phorbol myristate acetate and dioctanoylglycerol. The ability of ARIG to block the human AR induced by a variety of agonists and the fact that biological activity of the protein was lost after removal of its sugar moieties suggests that it may function as a general inhibitor of sperm exocytosis and that its interaction with spermatozoa may be mediated by carbohydrate-binding proteins on the sperm cell.

Acrosome↗
PubMed1995

Dietary chromium picolinate additions improve gain:feed and carcass characteristics in growing-finishing pigs and increase litter size in reproducing sows.

Growth trials were conducted to determine the effects of Cr as chromium picolinate at various protein levels on performance of growing pigs. The effects of continued supplementation on sow fecundity and body weight changes through two parities also were examined. In Trial 1, 48 crossbred pigs (40.9 kg initial weight) were assigned to one of three diets (0, 250, or 500 ppb of added Cr). The only observed difference was an overall trend for an improvement in gain:feed when Cr was added to the diet (P < .10). In Trial 2, 105 crossbred pigs (14.5 kg initial weight) were assigned to one of seven treatments involving a combination of two factors: 1) lysine level at 100 or 120% of NRC (1988) requirement estimate and 2) added Cr level (0, 100, 200, 500, or 1,000 ppb). A Cr x lysine interaction (P < .02) for gain:feed existed that demonstrated that the addition of 200 ppb of Cr resulted in improved gain:feed at the 100% of requirement lysine level but not at the 120% of requirement lysine level. The addition of 200 ppb Cr also reduced backfat (P < .04) and increased longissimus muscle area (P < .04) regardless of lysine level in the diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1995

Short report: dispersal of Aedes aegypti in an urban area after blood feeding as demonstrated by rubidium-marked eggs.

Strategies for the control of Aedes aegypti during urban outbreaks of dengue or yellow fever assume that this species has a maximum flight range of 50-100 meters. Because Ae. aegypti distributes its eggs among several oviposition sites, we postulated that dispersal is driven by the search for oviposition sites, so an ovipositing female may have to fly much further than 50-100 meters to lay all of her eggs. We developed a method for marking Ae. aegypti eggs with a rare alkali metal (rubidium) and showed that in an urban area, oviposition activity in a single gonotrophic cycle lasts several days and covers an area at least 840 meters in diameter (55.4 hectares). We suggest that current practice for the control of dengue and yellow fever transmission by focal treatments with insecticides 50-100 meters around presumed or confirmed cases is unlikely to be effective. Moreover, source reduction (the elimination of breeding sites) may enhance dissemination of virus-infected mosquitoes by reducing the number of available oviposition sites.

Aedes↗
PubMed1995

Effects of chromium and guar on sugar-induced hypertension in rats.

Ingestion of sugars (sucrose, fructose, glucose) by various rat strains is associated with perturbations in the glucose/insulin system and higher systolic blood pressure (SBP). The association suggests causality, because alterations in insulin metabolism have been found in essential hypertension and many experimental forms of hypertension. To test the hypothesis that sugar-induced SBP elevation is secondary to perturbed insulin metabolism, we examined in 2 experiments effects of chromium and guar, substances known to affect insulin metabolism, on SBP of Spontaneously Hypertensive Rats (SHR). In both studies, sucrose compared to starch ingestion caused significant elevation of SBP; but addition of 2 chromium nicotinate complexes and guar prevented development of sugar-induced SBP elevations. The basal, genetic hypertension of the SHR was not affected by either nutrient. An additional finding in the first study was that sugar-consuming SHR supplemented with chromium had greater BW and increased organ weight (kidney, spleen, and liver) than nonsupplemented SHR. Accordingly, we have shown that two different mechanisms known to ameliorate insulin perturbations, use of chromium and guar, prevent sugar-induced SBP elevations. Since essential hypertension may be due to insulin perturbations and high dose chromium supplementation seems nontoxic, this may prove to be a useful means to lower blood pressure (BP) in some essential hypertensives, as well as diabetic hypertensives. Soluble fiber in the form of guar is also quite effective in favorably influencing sugar-induced SBP elevations.

Animals↗
PubMed1995

Haemostatic effects of supraphysiological levels of testosterone in normal men.

The effects of exogenous testosterone on the haemostatic system were studied in a group of 32 healthy men undergoing a clinical trial of hormonal male contraception. The men received 200 mg testosterone oenanthate (TE) weekly i.m., and plasma samples were taken pretreatment, at defined time points up to 52 weeks of treatment, and 4 and 8 weeks after discontinuing TE. This dose of TE caused a 2-fold increase in trough plasma testosterone levels. TE caused a fall in plasma fibrinogen concentration after 16 weeks of treatment. This was sustained for the duration of TE treatment and recovered to pretreatment levels during the recovery phase. There was also a sustained fall in the level of C4b binding protein which showed a rebound to levels above pretreatment during recovery. Levels of antithrombin III and prothrombin fragment F1.2 rose initially during TE treatment, and levels of protein C, protein S (free) and plasminogen activator inhibitor fell, but the concentrations of these factors all returned to pretreatment levels during continued treatment. There was no change in the plasma concentrations of beta-thromboglobulin, tissue plasminogen activator, protein S (total), or D-dimer. There was a sustained increase in haemoglobin concentration and haematocrit, without any change in platelet count. The observed changes were consistent with mild activation of the haemostatic system during initial treatment with testosterone. After several months the raised activation markers had returned to pretreatment levels indicating that a new equilibrium had been established which did not appear to be prothrombotic.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Type I phosphatidylinositol 4-phosphate 5-kinase isoforms are specifically stimulated by phosphatidic acid.

A phosphatidylinositol 4-phosphate (PIP) kinase was isolated and purified to near homogeneity from bovine erythrocyte membranes. The PIP kinase was extracted from bovine erythrocyte membranes with a high salt wash, followed by phosphocellulose and phenyl-Sepharose chromatography. The predominant protein after phenyl-Sepharose purification had a molecular size of 68 kDa. Renaturation of PIP kinase activity after SDS-PAGE showed that a 68-kDa protein was able to phosphorylate PIP. An antibody developed against the 68-kDa protein Western blots the 68-kDa protein and is able to immunoprecipitate the 68-kDa protein and PIP kinase activity from membrane extracts. Based on functional studies, the 68-kDa protein is indistinguishable from the type I PIP kinase previously characterized from human erythrocyte membranes (Bazenet, C. E., Ruano, A.R., Brockman, J.L., and Anderson, R.A. (1990) J. Biol. Chem. 265, 18012-18022). These studies also show that the type I PIP kinases, but not the type II PIP kinase, are stimulated by phosphatidic acid, suggesting alternative roles for these enzymes. Two immunoreactive isoforms of the type I PIP kinase, of 68 and 90 kDa, were identified in rat brain and partially purified. Both of these isoforms are also stimulated by phosphatidic acid.

Animals↗
PubMed1994

Mutations at the lysosomal acid cholesteryl ester hydrolase gene locus in Wolman disease.

The genomic sequences encoding the human lysosomal acid lipase/cholesteryl esterase (sterol esterase; EC 3.1.1.13) have been isolated and sequenced, and the information has been used to identify mutations in both alleles of the gene from a patient with Wolman disease, an autosomal recessive lysosomal lipid storage disorder. The genomic locus consists of 10 exons spread over 36 kb. The 5' flanking region is G+C-rich and has characteristics of a "housekeeping" gene promoter. One of the identified mutations involves the insertion of a T residue after position 634, resulting in the appearance of an in-frame translation stop signal 13 codons downstream. The second mutation is a T-to-C transition at nucleotide 638. This results in a leucine-to-proline substitution at amino acid 179 and is predicted to lead to the disruption of the alpha-helical structure in a highly conserved region of the protein. These mutations are each capable of completely disrupting the catalytic function of the lysosomal acid cholesteryl ester hydrolase; their presence can account for the extreme phenotype of the lysosomal lipid storage disorder manifested in members of this patient's family.

Amino Acid Sequence↗
PubMed1994

A non-invasive method for postmortem temperature measurements using a microwave probe.

The use of the Microwave Thermography System in Forensic Medicine for the estimation of the post-mortem interval is explained. The Microwave Thermography System, a new device which is applied to this field for the first time, is described and its mode of operation is discussed. The main advantage of using this device for estimating the time after death is its ability to measure internal body temperatures by a non-invasive method. Using this device, it is possible now to measure temperatures of internal organs of the body by placing the sensory elements on the skin. Reliability of the system and factors affecting the accuracy of post-mortem temperature measurements have been assessed and discussed.

Adult↗
PubMed1994

Are capacitation or calcium ion influx required for the human sperm acrosome reaction?

OBJECTIVE: To determine if the acrosome reaction of human spermatozoa can occur without prior incubation to induce capacitation or in calcium-free medium. DESIGN: Noncapacitated (washed ejaculated) or capacitated (incubated for 3 hours in the presence of albumin) human spermatozoa were treated with either solubilized zonae pellucidae (ZP); a calcium ionophore (A23187); or activators of protein kinases A, G, and C, and the acrosomal status was monitored by the double stain technique. During agonist treatment, the capacitated spermatozoa were in medium either with or without calcium ions (Ca2+). The noncapacitated spermatozoa were always in Ca(2+)-containing medium. Sperm motility was monitored throughout the experiments. RESULTS: Solubilized ZP and kinase activators induced acrosomal exocytosis of capacitated spermatozoa (both in Ca(2+)-containing and Ca(2+)-free medium) and of noncapacitated spermatozoa. The lack of added Ca2+ or capacitation reduced the percentage of spermatozoa that reacted in response to solubilized ZP but not to the kinase activators. Ionophore A23187 stimulated acrosomal loss from noncapacitated spermatozoa to the same extent as capacitated spermatozoa in Ca(2+)-containing medium but had no effect on capacitated spermatozoa in Ca(2+)-free medium. CONCLUSIONS: Human spermatozoa do not require incubation under capacitating conditions or the presence of extracellular Ca2+ before they can undergo the acrosome reaction in response to certain agonists. Therefore, Ca2+ influx and/or preincubation to induce capacitation are not absolute requirements for the in vitro agonist-induced acrosome reaction. However, these conditions can optimize the acrosome reaction response to zona proteins. The intracellular mechanisms leading to the acrosome reaction appear to be functional in noncapacitated spermatozoa but membrane changes probably are required before certain extracellular ligands such as zona proteins can exert their maximal effect.

Acrosome↗
PubMed1994

Issues regarding aggregation of data in nursing systems research.

The unit of analysis at which variables are conceptualized and measured is an important consideration when conducting patient outcomes research. Outcomes research ranges from study of individual responses to nursing intervention to investigation of group level outcomes associated with the contexts and processes through which nursing care is delivered. Because many variables salient to the investigation of group level patient outcomes are not amenable to direct measurement, aggregation procedures are used to generate proxy measurement of organizational context or process variables. In this article, key conceptual and methodologic issues encountered when using data aggregation procedures are reviewed. Following this, estimation of aggregated data reliability is illustrated using data from a study conducted to investigate skilled nursing unit structures.

Data Interpretation, Statistical↗
PubMed1993

Identification of a family of casein kinases in Paramecium: biochemical characterization and cellular localization.

Protein phosphorylation is believed to play a role in the regulation of ciliary motility in the protozoan Paramecium tetraurelia. Five protein kinases from Paramecium, activated by cyclic nucleotides or Ca2+, have been characterized previously. We report here the identification of a family of second-messenger-independent casein kinases in Paramecium. Casein kinase activity was enriched in the soluble fraction of cilia, but there was also significant activity tightly associated with axonemes. Three ciliary casein kinase activities (soluble CKS1 and CKS2, and axonemal CKA) were separated by chromatography and characterized. The native forms of all three were monomeric, with molecular masses of 28-45 kDa as judged by in-gel kinase assays and sizing by gel filtration. CKS2 was inhibited by heparin, but CKA was unaffected and CKS1 was stimulated. All three activities preferred acidic substrates such as casein and phosvitin, but they could be distinguished by their preference for other substrates. Antibodies against mammalian casein kinase I recognized CKS1 and CKS2 in immunoblots (43 kDa), but did not stain CKA. The antibodies to casein kinase I were used to probe other cellular fractions. A 65 kDa antigen (particulate casein kinase, CKP) was enriched in particulate fractions of whole cells. This 65 kDa protein was found in isolated cell cortices, but was not present in the infraciliary lattice. This report represents the first biochemical identification of a casein kinase I family in protozoa.

Animals↗
PubMed1993

Metabolic correction and cross-correction of mucopolysaccharidosis type II (Hunter syndrome) by retroviral-mediated gene transfer and expression of human iduronate-2-sulfatase.

To explore the possibility of using gene transfer to provide iduronate-2-sulfatase (IDS; EC 3.1.6.13) enzyme activity for treatment of Hunter syndrome, an amphotropic retroviral vector, L2SN, containing the human IDS coding sequence was constructed and studied for gene expression in vitro. Lymphoblastoid cell lines (LCLs) from patients with Hunter syndrome were transduced with L2SN and expressed high levels of IDS enzyme activity, 10- to 70-fold higher than normal human peripheral blood leukocytes or LCLs. Such L2SN-transduced LCLs failed to show accumulation of 35SO4 into glycosaminoglycan (35SO4-GAG), indicating that recombinant IDS enzyme participated in GAG metabolism. Coculture of L2SN-transduced LCLs with fibroblasts from patients with Hunter syndrome reduced the accumulation of 35SO4-GAG. These results demonstrated retroviral-mediated IDS gene transfer into lymphoid cells and the ability of such cells to provide recombinant enzyme for intercellular metabolic cross-correction.

Base Sequence↗