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Biomedical subjects

L Harrington

Publications and source records attributed to L Harrington.

At least 37 records · Page 2Linked to original sources
PubMed1997

Reciprocal inhibitory paracrine pathways link histamine and somatostatin secretion in the fundus of the stomach.

The present study was designed to examine the functional linkage between histamine and somatostatin secretion in the fundus of the stomach. In segments of rat fundic mucosa, superfusion with thioperamide (H3 antagonist) increased somatostatin and decreased histamine secretion; superfusion with (R)(-)-alpha-methylhistamine (H3 agonist) had the opposite effect, decreasing somatostatin and increasing histamine secretion. The pattern implied that endogenous histamine, acting via H3 receptors, exerts an inhibitory paracrine influence on somatostatin secretion. Superfusion with somatostatin antibody (1:250) increased histamine secretion, implying that endogenous somatostatin, in turn, exerts an inhibitory paracrine influence on histamine secretion. Somatostatin antibody also abolished the decrease in histamine secretion induced by thioperamide and the increase in histamine secretion induced by (R)(-)-alpha-methylhistamine, implying that changes in histamine secretion induced by activation of H3 receptors reflect changes in somatostatin secretion. Superfusion with the muscarinic agonist methacholine alone and in the presence of either H3 agonist or H3 antagonist confirmed the existence of reciprocal inhibitory pathways linking somatostatin and histamine. We conclude that fundic histamine and somatostatin secretion are linked via reciprocal inhibitory paracrine pathways that serve to amplify the regulatory influence of somatostatin.

Animals↗
PubMed1996

Somatostatin receptor subtype 2 mediates inhibition of gastrin and histamine secretion from human, dog, and rat antrum.

BACKGROUND & AIMS: In gastric antrum, somatostatin exerts a tonic inhibitory influence on gastrin and histamine secretion. Five different subtypes of somatostatin receptors, designated sst1-5, have been identified. sst2, sst3, and sst5 subtypes have been localized to the stomach by molecular biological techniques. The aim of this study was to identify the sst subtype regulating gastrin and histamine secretion in human, dog, and rat stomach. METHODS: Mucosal segments from human, dog, and rat antrum were superfused with various concentrations of somatostatin 14 and somatostatin analogues selective for sst2, sst3, and sst5. Gastrin and histamine were measured by radioimmunoassay. RESULTS: Somatostatin 14 and the sst2 agonist EC 5-20 inhibited gastrin and histamine secretion from all three species in a concentration-dependent manner, whereas the sst3 and sst5 agonists had no significant effect. Neutralization of endogenous somatostatin with the somatostatin antibody increased gastrin and histamine secretion. The increases were not affected by the gastrin antagonist but were abolished by the sst2 agonist, implying that the inhibitory influence of ambient somatostatin is exerted directly on the histamine cell rather than indirectly via changes in gastrin secretion. CONCLUSIONS: Somatostatin inhibits gastrin and histamine secretion in human, dog, and rat antrum by activating sst2 receptors on gastrin and histamine cells.

Animals↗
PubMed1995

Gel shift and UV cross-linking analysis of Tetrahymena telomerase.

Telomerase is an unusual ribonucleoprotein that synthesizes new telomeres onto chromosome ends. The enzyme has been most extensively characterized in ciliates, where the RNA component has been cloned from several species, and its elongation properties have been characterized in detail. To understand the substrate specificity and protein composition of telomerase, we have used gel shift and UV cross-linking to characterize the enzyme from the ciliate Tetrahymena thermophila. In a mobility shift assay, a complex was identified that contained telomerase RNA, co-purified with telomerase activity, and was sensitive to nuclease treatment. The mobility shift complexes specifically formed using several different single-stranded, telomeric sequences but not non-telomeric primers. These results suggest that the specificity of telomerase for G-rich primer sequences occurs at least in part at the level of primer binding. UV cross-linking analysis identified a 100-kDa cross-linked protein that may be a telomerase component.

Animals↗
PubMed1995

Dual inhibitory pathways link antral somatostatin and histamine secretion in human, dog, and rat stomach.

BACKGROUND & AIMS: The secretion and function of antral histamine are not known. The aims of this study were to characterize the mechanisms of histamine release from the gastric antrum of humans, dogs, and rats and to determine whether histamine can influence the secretion of somatostatin and gastrin. METHODS: Somatostatin, gastrin, and histamine secretion from superfused antral segments was measured using radioimmunoassay. RESULTS: Superfusion with thioperamide (H3 antagonist) increased somatostatin and decreased gastrin and histamine secretion in all three species; superfusion with (r)-alpha-methylhistamine (H3 agonist) had the opposite effect. The pattern implied that endogenous histamine, acting via H3 receptors, exerts an inhibitory paracrine influence on somatostatin secretion, which in turn regulates gastrin secretion. Superfusion with somatostatin antibody increased histamine secretion; the increase was not affected by the gastrin antagonist L-365,260, implying that it was not mediated by the concurrent increase in gastrin but by suppression of an inhibitory pathway linking somatostatin and histamine. Superfusion with methacholine alone and in the presence of either the H3 agonist or antagonist confirmed the existence of reciprocal inhibitory pathways linking somatostatin and histamine. CONCLUSIONS: Antral histamine in humans, dogs, and rats is linked to antral somatostatin via reciprocal inhibitory paracrine pathways that serve to amplify the regulatory influence of somatostatin.

Animals↗
PubMed1995

Complete nucleotide sequence of the herpesvirus simiae glycoprotein G gene and its expression as an immunogenic fusion protein in bacteria.

The nucleotide sequence of a 2384 bp portion within the unique short (Us) region of the herpesvirus simiae (simian herpes B virus; SHBV) genome is presented. A partial and a complete open reading frame (ORF) were found within this nucleotide sequence. The partial ORF encodes the C terminus (147 amino acids) of a protein kinase which is highly conserved in the herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) and simian agent 8 (SA8) Us regions. The complete ORF is located 3' to the partial ORF within the 2384 bp sequence and encodes a 593 amino acid glycoprotein which appears to be closely related to the SA8 glycoprotein G (gG), but shares little amino acid similarity with gG of HSV-1 and -2. However, the complete ORF shares certain features conserved among most alphaherpesvirus gGs, notably three highly conserved cysteine residues and an adjacent N-glycosylation site. Therefore, it was concluded that this complete ORF encodes the SHBV gG. The 358 amino acid C-terminal portion of SHBV gG was expressed in Escherichia coli as a fusion protein and this was detected by immunoblotting with sera from cynomolgus monkeys which were either experimentally or naturally infected with SHBV. The purified fusion protein was inoculated into rabbits to raise an antiserum which recognized a number of apparently SHBV gG-specific protein bands in extracts from SHBV-infected simian cells.

Amino Acid Sequence↗
PubMed1995

Determination of radiation energy emitted by light activation units.

Since the introduction in the 1970s of single paste composite materials, there has been a rapid increase in the range of both materials and activation light units. This investigation is being undertaken as part of a larger study where the characteristics of both composite materials, light activation units and composite material/light activation unit combinations, are being evaluated. This section of the study was undertaken to determine the characteristics of four light activation units. The equipment was developed to measure radiation energy over a wide range of illumination. This range can be from the relatively low intensity of radiation transmitted through restorative materials to the intensities of direct radiation from light activation units. The four light units tested had various radiation outputs between 225,000 lx and 75,000 lx. All the units, apart from one, showed a decrease in light output with successive applications. The units emitted radiation outside the optimum range of 440-500 nm, which may produce damaging radiation and glare. Although the extreme intensities varied threefold the effect on depth of cure of one-material varied by only 16%.

Composite Resins↗
PubMed1995

Differences in the hypothalamic-pituitary-adrenal axis of black and white men.

We previously found that, following intravenous administration of ovine corticotropin-releasing hormone (CRH), the plasma ACTH concentrations of Black women were approximately twice as high as those of White women; however, there were no corresponding differences in cortisol response. To determine whether this difference in ACTH secretion is also present in men, we studied the hypothalamic-pituitary-adrenal axis of 10 Black and 10 White weight-, age-, and education-matched men. Waist-to-hip ratio, 24-hour urine free cortisol excretion, and ACTH and cortisol responses to 1 microgram/kg ovine CRH were determined. There were no racial differences in waist-to-hip ratio, 24-hour urine free cortisol excretion, baseline free or total plasma cortisol and ACTH concentrations, or plasma cortisol response to CRH. However, CRH-stimulated plasma ACTH concentrations, measured in an extraction polyclonal radioimmunoassay, were significantly greater in Blacks than in Whites at all time points between 30 and 180 min after administration of CRH (area under curve (AUC) 1,796 +/- 245 pmol/l.min in Blacks vs. 1,278 +/- 121 pmol/l.min in Whites, p < 0.001). Neither cortisol nor ACTH AUCs were significantly correlated with Body Mass Index in Black or White men. We conclude that there are differences in the HPA axis of Black and White men similar to those found previously in women. The physiology underlying these differences remains to be understood.

Adrenocorticotropic Hormone↗
PubMed1993

Temporal covariation of soluble interleukin-2 receptor levels, daily stress, and disease activity in rheumatoid arthritis.

OBJECTIVE: To examine synchronous changes in soluble interleukin-2 receptor (sIL-2R) levels, daily indicators of emotional stress, joint inflammation, and reported pain in patients with rheumatoid arthritis (RA). METHODS: Fourteen patients were studied on each of 6 occasions, 2 weeks apart. Measures included daily ratings of mood disturbance, undesirable events, and joint pain; clinical examination of joint swelling; and serum assays of sIL-2R. Pooled within-person correlations among these variables were calculated. RESULTS: Consistent with the results of previous research, joint inflammation covaried directly with sIL-2R levels. Changes in mood disturbance were unrelated to changes in joint inflammation, but increases in mood disturbance were linked with decreases in sIL-2R levels and increases in reported joint pain. CONCLUSION: These findings provide preliminary evidence that psychoimmune processes may be implicated in short-term changes in RA disease activity.

Adult↗
PubMed1993

Polymerase chain reaction for detection of herpesvirus simiae (B virus) in clinical specimens.

A polymerase chain reaction (PCR) was designed which is specific to Macaca fascicularis (cynomolgus monkey) isolates of B virus. The PCR primers produced the expected 188 basepair product from the Cyno 2 strain and seven other cynomolgus monkey isolates of B virus. Oligomer hybridization with a 31-mer oligonucleotide was used to confirm the origin of this product. The PCR failed to amplify DNA of Epstein-Barr virus, cytomegalovirus, varicella-zoster virus, and other alphaherpesviruses (herpes simplex virus types 1 and 2, four SA 8 isolates and three rhesus isolates of B virus). PCR testing of swabs obtained from four orally-infected cynomolgus monkeys confirmed the presence of B virus DNA in samples previously shown to be positive by culture. In addition, PCR detected B virus in several swabs from infected monkeys that were culture negative. Total DNA extracts from the trigeminal and sacral ganglia of these animals were tested by nested PCR and B virus DNA was detected in the trigeminal ganglia of 3 of the 4 orally-infected cynomolgus monkeys. Nested PCR did not detect B virus DNA in total DNA extracts obtained from the brains of the four monkeys.

Animals↗
PubMed1993

Procainamide-induced psychosis.

The occurrence of procainamide-induced psychosis has not been mentioned previously in the nursing literature and is rarely reported in the medical literature. With the increasing use of procainamide in patients with both atrial and ventricular dysrhythmias, it is quite possible that nurses may encounter the phenomenon more frequently. It is also possible that it has been mistaken previously for ICU or psychologically-induced psychosis. Nurses routinely monitoring patients for physiologic effects of procainamide should also be alert for psychological effects as well. The onset of acute psychological sequelae such as procainamide-induced psychosis further complicates care of physiologically compromised patients. Rapid identification and intervention is important. It is especially important to listen to patient and family cues.

Aged↗
PubMed1993

Air embolism and CVCs.

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Catheterization, Central Venous↗
PubMed1992

Nucleotide sequence analysis of a homologue of herpes simplex virus type 1 gene US9 found in the genome of simian herpes B virus.

The 10K gene of simian herpes B virus (SHBV) has been located and the nucleotide sequence determined. Its relationship to homologous genes in other herpes-viruses has been examined. The SHBV 10K gene exhibits a closer relationship to its homologue in HSV-1 than to those in the other viruses studied. Nucleotide sequence identity of 61% was found between the HSV-1 and SHBV 10K genes, and 57% identity was found between the corresponding predicted protein sequences. A comparison of the amino acid sequences of the herpesvirus 10K proteins has revealed a number of conserved features. These are examined in relation to possible functions of the 10K proteins. Implications for evolutionary relationships between SHBV and other herpesviruses are discussed.

Amino Acid Sequence↗
PubMed1992

Nucleotide sequence analysis of genes encoding glycoproteins D and J in simian herpes B virus.

The gene encoding glycoprotein D (gD) of simian herpes B virus (SHBV) was identified by hybridization with the gD gene of herpes simplex virus type 1 (HSV-1). The gene probe bound to a 2.6 kbp SalI-EcoRI fragment of SHBV DNA, which was cloned into a plasmid vector. The nucleotide sequence of the SHBV DNA fragment was determined. Two complete and one partial open reading frames (ORFs) were found. The nucleotide sequences of the two complete ORFs are 57% and 69% identical to HSV-1 genes US5 (encoding gJ) and US6 (encoding gD), respectively. The partial ORF showed 64% similarity with HSV-1 US7 (encoding gI). The SHBV gD gene revealed many features which are also found in the gD homologues of other herpesviruses. The positions of cysteine residues and receptor-binding sites for the predicted protein are shown to be highly conserved.

Amino Acid Sequence↗
PubMed1992

Molecular cloning and physical mapping of the genome of simian herpes B virus and comparison of genome organization with that of herpes simplex virus type 1.

The molecular structure of the genome of simian herpes B virus (SHBV) was determined by restriction endonuclease mapping studies. Genomic DNA was cleaved with restriction endonucleases BamHI and SalI into 41 and 58 fragments, respectively. Most of these fragments were cloned into the plasmid vector pACYC184; uncloned fragments were identified following isolation from agarose gels. Terminal fragments were identified by exonuclease digestion and radioactive end-labelling, and linkage of fragments was deduced by a combination of single and double digest experiments and cross-blot hybridizations. The genome is larger than that of herpes simplex virus type 1 (HSV-1), being approximately 165 kilobase pairs. Like that of HSV-1, the SHBV genome is composed of a long and a short unique region each flanked by inverted repeat sequences, which allow the unique regions to invert relative to one another, resulting in four possible isomeric arrangements of the molecule. Genome locations of several SHBV genes were compared with their HSV-1 homologues.

Animals↗
PubMed1991

Post's program and incomplete recursively enumerable sets.

A set A of nonnegative integers is recursively enumerable (r.e.) if A can be computably listed. It is shown that there is a first-order property, Q(X), definable in E, the lattice of r.e. sets under inclusion, such that (i) if A is any r.e. set satisfying Q(A) then A is nonrecursive and Turing incomplete and (ii) there exists an r.e. set A satisfying Q(A). This resolves a long open question stemming from Post's program of 1944, and it sheds light on the fundamental problem of the relationship between the algebraic structure of an r.e. set A and the (Turing) degree of information that A encodes.

Journal Article↗