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Biomedical subjects

R M Martin

Publications and source records attributed to R M Martin.

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

Myophilin of Echinococcus granulosus: isoforms and phosphorylation by protein kinase C.

Myophilin is a muscle-associated antigen of the taeniid cestode Echinococcus granulosus. This protein shows a high amino acid sequence homology with calponins and calponin-like proteins, which are proposed to be associated with the regulation of smooth muscle contraction. In order to provide supportive evidence for a relationship between these proteins, we characterized myophilin using electrophoretic, biochemical and molecular biological approaches. Two-dimensional protein electrophoretic separation of E. granulosus larval proteins defined 4 isoelectric isoforms of myophilin (alpha, beta, gamma and delta), which appeared to be a consequence of post-translational modification of a single gene product. It was also demonstrated biochemically that E. granulosus myophilin undergoes specific phosphorylation in vitro by protein kinase C (PKC). Finally, myophilin homologues were identified in extracts of Taenia hydatigena and T. ovis by immunoblot. A partial cDNA of the closely related species, E. multilocularis, was isolated by cloning procedures and showed 99% homology with the E. granulosus myophilin gene. The similarities of E. granulosus myophilin with calponins in their tissue localization, protein isoforms patterns, ability to be phosphorylated in vitro by PKC, and the relatively conserved nature of the protein among related parasites suggest that myophilin may be associated with smooth muscle contraction.

Animals↗
PubMed1997

Helicobacter pylori serology and the management of young dyspeptics: a UK survey of gastroenterologists and general practitioners with an interest in gastroenterology.

AIM: To survey the current use of Helicobacter pylori serology for pre-endoscopy screening and management of young dyspeptics amongst gastroenterologists and general practitioners with an interest in gastroenterology in the United Kingdom. METHODS: A postal questionnaire was sent to 536 members of the British Society of Gastroenterology and 164 members of the Primary Care Society in Gastroenterology. RESULTS: Of those who responded (66%), 25% of general practitioners and 17% of gastroenterologists were using H. pylori serology as a screening test for young dyspeptics. General practitioners and gastroenterologists differed in their use of serology to guide management strategies (P < 0.0003): general practitioners eradicate infection from sero-positive patients prior to endoscopy (92%), whilst the majority of gastroenterologists endoscope sero-positive patients before treatment (55%). More gastroenterologists (89%) would re-test all or selected patients to assess eradication compared to general practitioners (45%). 106 different drug regimes were being used as first line treatment. CONCLUSIONS: H. pylori serology as a pre-endoscopy screening test for young dyspeptic patients was used by only a fifth of respondents. There were wide variations in attitudes and practice in the way H. pylori serology was used in the management of young dyspeptics. Trials comparing clinical outcome and cost-effectiveness of different serology-based strategies are needed.

Adult↗
PubMed1997

The impact of the October 1995 'pill scare' on oral contraceptive use in the United Kingdom: analysis of a general practice automated database.

OBJECTIVES: We aimed to measure the change in prescribing of oral contraceptives after the October 1995 UK 'pill-scare'. DESIGN: Analysis was undertaken of an automated database of 100 general practices (372 doctors) in England, Scotland and Wales which use the AAH Meditel computer system. Analysis involved two stages. First, we reviewed prescribing of oral contraceptives at three time periods: before the scare (18.10.95); the following three months (19.10.95-18.1.96); and 3-6 months post-scare (19.1.96-18.4.96). Second, we examined the cohort of women on the pill at the time of the scare to assess discontinuation rates and pill switches after 6 months. RESULTS: Six months after the scare the proportion of women between 16 and 50 years of age prescribed any contraceptive pill decreased by only 3.5% (95% confidence limits: 2.2%-4.8%). The proportion of pill-users prescribed third generation pills decreased from 53.4% to 18.1%, while prescribing of second generation pills increased from 20.1% to 48.4%. The proportion of women currently on third or second generation pills at the time of the scare, who were no longer prescribed any pill after 6 months, was the same as for the equivalent period in the previous year. CONCLUSIONS: The number of women prescribed the pill did not alter markedly after the pill-scare. The main change was a switch from third to second generation pill types. In any future pill-scare women should be warned about the risk of pill-failure if the correct procedure for switching pills is not followed.

Adolescent↗
PubMed1996

Antibody responses of patients with cystic hydatid disease to recombinant myophilin of Echinococcus granulosus.

Hydatid patients were investigated for the presence of specific serum antibodies against a recombinant Echinococcus granulosus antigen, designated myophilin. The clinical history of each patient was examined to determine any correlation between factors such as cyst location and medical treatment on the presence or absence of antibodies to myophilin. Specific antibodies against recombinant myophilin were detected by Western blot analysis in 38.8% (7 of 18) of the hydatid patients examined. These patients also had the highest titres in ELISA against sheep hydatid cyst fluid antigen. There was an association between the presence of antibodies to myophilin and the patients having undergone recent treatment by chemotherapy and/or surgery, suggesting that the destruction of hydatid cysts may lead to an immune response against myophilin.

Adult↗
PubMed1995

Identification and characterization of myophilin, a muscle-specific antigen of Echinococcus granulosus.

A muscle-specific gene of Echinococcus granulosus has been identified and characterized. A lambda gt11 clone (10P1), containing an incomplete copy of the gene, was originally isolated from a larval E. granulosus cDNA library by serum antibodies from dogs infected with the parasite. The full-length cDNA sequence was obtained by PCR amplification of cDNA from an adult E. granulosus lambda gt22A library. Southern blot analysis indicated the presence of the gene as a single copy in the genome of E. granulosus and also detected homologous genes in genomic DNA of E. multilocularis and Taenia saginata. The 21.2-kDa protein deduced from the complete cDNA sequence contains two regions of 12 amino acids with similarity to the EF-hand motif of calcium binding proteins. Antibodies raised against the purified 10P1-GST fusion protein detected a 22-kDa antigen in the E. granulosus developmental stages examined. Immunoelectron microscopy localized the native protein in the muscle of the parasite. The amino-acid sequence of the E. granulosus protein shows significant homology to the muscle proteins mp20 of Drosophila melanogaster, chicken SM22 alpha and mammalian calponin, and also to the neuronal protein NP25 of rats. A conserved carboxy-terminal motif of 17 amino acids is present in all the homologous proteins and is proposed to be the characteristic feature of a novel protein family. The term myophilin is proposed for the E. granulosus protein due to its localization and homology to other muscle proteins.

Amino Acid Sequence↗
PubMed1990

Effects of the pre-column in automated on-column injection capillary gas chromatography.

In this work, we investigated the effects of pre-columns and press-fit connectors on automated cold on-column injection capillary gas chromatography. Verapamil, a calcium channel blocking vasodilator used in the treatment of angina, arrhythmias and hypertension, and norverapamil, an active metabolite, were used as model compounds in these investigations. Wide-bore fused-silica tubing deactivated with OV-1701-vinyl was also studied with respect to its suitability as pre-column material. The detector response of verapamil versus an internal standard was consistent at micrograms/ml and ng/ml levels, while that of norverapamil decreased with the amount injected. However, the decrease in response of norverapamil appeared to be unrelated to the presence of a pre-column or press-fit connector in the chromatographic system.

Chromatography, Gas↗
PubMed1990

The effect of M1 muscarinic blockade on behavior and physiological responses following traumatic brain injury in the rat.

Dicyclomine (1 mg/kg or 10 mg/kg), scopolamine (1 mg/kg), or saline was administered intraperitoneally to rats 15 min prior to moderate fluid percussion brain injury. A variety of reflexes and responses were measured up to 60 min following injury, and body weight and several neurological measures were taken daily up to 10 days following injury. All 3 antimuscarinic treatments reduced the duration of transient behavioral suppression as assessed by these measures. It appears that blockade of the M1 muscarinic receptor can attenuate transient behavioral suppression associated with concussive brain injury. Thus, stimulation of M1 muscarinic receptors may mediate components of reversible traumatic unconsciousness following cerebral concussion. No differences were observed between saline and antimuscarinic treatments in the incidence or duration of apnea following injury. Scopolamine pretreatment significantly elevated heart rate prior to injury, but had no significant effect on the responses of heart rate and blood pressure to experimental concussion. Both doses of dicyclomine significantly reduced resting heart rate, but unlike scopolamine, significantly enhanced the cardiovascular response to fluid percussion injury. Antimuscarinic treatment significantly reduced body weight loss and certain motor deficits, including beam balance and beam walk performance, following concussive head injury. Scopolamine and both doses of dicyclomine appeared to be equally effective in reducing long-term deficits. Data from these experiments indicate that at least some of the long-term behavioral deficits following moderate levels of brain injury may involve the binding of acetylcholine to M1 muscarinic receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

The effect of acetylcholine depletion on behavior following traumatic brain injury.

Rats were injected with either saline; A-4 (40 mg/kg, i.p.), a bis tertiary amine derivative of hemicholinium-3; or A-5 (50 micrograms/kg, i.p.), a bis quaternary amine derivative of hemicholinium-3, 1 h prior to moderate fluid percussion brain injury. A variety of reflexes and responses were measured up to 60 min following injury, and body weight and several neurological measures were taken daily up to 10 days following injury. Pretreatment with either A-4 or A-5 significantly attenuated components of transient behavioral suppression, as well as more enduring deficits in body weight and beam walk and beam balance performance. A-4 administered prior to fluid percussion was found to reduce striatal, but not pontine, acetylcholine content. A-5 did not significantly reduce acetylcholine content in either area. Both A-4 and A-5 pretreatment prevented a significant increase in acetylcholine content in the cerebrospinal fluid following fluid percussion injury; however, only A-5 significantly reduced plasma acetylcholine content. These results confirm cholinergic involvement in the production of both transient and longer-lasting behavioral deficits following traumatic brain injury. Furthermore, traumatic brain injury may allow plasma constituents to gain access to the central nervous system.

Acetylcholine↗
PubMed1989

The effects of morphine and traumatic brain injury on central cholinergic neurons.

This study examined the effects of morphine and fluid percussion traumatic brain injury (TBI) on the activity of cholinergic neurons in specific areas of the rat brain 12 min after injury. Acetylcholine (ACh) turnover, used as an index of cholinergic neuronal activity, was determined using gas chromatography-mass spectrometry. Although morphine administration alone in general did not significantly affect ACh content and turnover in specific brain areas, morphine administered prior to TBI either prevented injury-induced changes in ACh turnover (dorsal pontine tegmentum) or actually reduced the rate constant for ACh utilization (kACh) and the turnover rate of ACh (TRACh) following injury (thalamus, amygdala, cingulate/frontal cortex, and hippocampus). Thus, the protective effects of morphine against enduring behavioral deficits following TBI may involve the inhibition of central cholinergic neurons.

Acetylcholine↗
PubMed1988

Disposition of the plant phenol ellagic acid in the mouse following oral administration by gavage.

1. The absorption, distribution and elimination of 3H-ellagic acid, a putative antimutagen and anticarcinogen, was studied in male Swiss-Webster mice following oral administration. 2. Levels of 3H-ellagic acid were highest in blood 30 min after administration, in urine and bile 120 min post-administration, and in liver, lung and kidney 15 min after administration [corrected]. 3. Free ellagic acid and its conjugates were present in urine, bile and blood. H.p.l.c. analysis of the organic solvent extracts of urine, bile and blood indicated the presence of four metabolites in urine, two in blood and one in bile. 4. Sulphate ester, glucuronide and glutathione conjugates of ellagic acid were present in urine, bile and blood. H.p.l.c. analysis of organic solvent extracts after aryl sulphatase or beta-glucuronidase treatment showed that ellagic acid was the major component present. 5. Absorption of 3H-ellagic acid occurred mostly within two hours after oral administration. Levels in blood, bile and tissues were low and almost all of the absorbed dose was excreted in urine. 6. More than 53% of the orally administered 3H-ellagic acid remained in the gastrointestinal tract at 24 h. Approximately 19% was excreted in faeces and 22% in urine at 24 h. 7. Of the 24 h faecal radioactivity 93% was extractable into organic solvents and more than 80% of this fraction was free ellagic acid. Only one metabolite was found in faeces.

Administration, Oral↗
PubMed1987

Ellagic acid metabolism and binding to DNA in organ explant cultures of the rat.

Ellagic acid (EA) is a plant phenolic compound with postulated antimutagenic and anticarcinogenic activity. In this study, explants of esophagus, forestomach, colon, bladder, trachea, lung and liver from male Sprague-Dawley rats (130-140 g) were incubated in culture medium containing [3H]EA (20 microM, 4.5 microCi/ml) for 24 h at 37 degrees C. After extraction, purification and quantitation of explant DNA significant differences in the binding of EA to the DNA was observed. The most binding occurred in esophagus and the least in lung. Analysis of the organsoluble fraction of the culture medium by high performance liquid chromatography yielded 3 metabolites of EA. None of the metabolites were identified. Elution of water-soluble metabolites from an alumina column showed that there were sulfate ester, glucuronide and glutathione conjugates of EA in the explant culture medium from all the organs. The profile of water-soluble conjugates was very similar between colon and forestomach and between trachea and lung. These results indicate that EA binds to DNA in different tissues and that tissues metabolize EA to both organosoluble and water-soluble products.

Animals↗