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Biomedical subjects

A Milne

Publications and source records attributed to A Milne.

At least 37 records · Page 2Linked to original sources
PubMed1994

Amino acid losses in ileostomy fluid on a protein-free diet.

The contribution of losses via the gastrointestinal tract to maintenance amino acid requirements was assessed by collecting the ileostomy fluid of volunteers given a protein-free diet for 5 d. The subjects were eight adult men and women with terminal ileum ileostomies after ulcerative colitis. Four consecutive 24-h collections of both digesta and urine were made. On the last 2 d an antibiotic was given that suppressed microbial activity in the digesta and slightly reduced ileostomy outflow. Mean daily amino acid excretion in ileostomy fluid ranged from 32 mg/d for methionine to approximately 330 mg/d for aspartate and glutamate. These losses were compared with current international estimates of amino acid requirements. For most essential amino acids gastrointestinal losses accounted for 14-33% of daily maintenance requirements but for threonine the contribution was 61%.

Amino Acids↗
PubMed1994

Contractions mediated by alpha 1-adrenoceptors and P2-purinoceptors in a cat colon circular muscle.

1. The postjunctional excitatory and inhibitory effects of adrenoceptor and purinoceptor agonists and antagonists were studied in circular smooth muscle strips of cat colon. 2. In the presence of tetrodotoxin (0.5 microM), noradrenaline caused contraction or relaxation of circular smooth muscle at resting tension or with raised tone, respectively. The noradrenaline-evoked contractions were potentiated and the noradrenaline-evoked relaxations were antagonized by propranolol (1 microM), suggesting beta-adrenoceptor involvement. 3. At resting tension, noradrenaline, adrenaline and the selective alpha 1-adrenoceptor agonist, phenylephrine, caused concentration-dependent contractile responses, with EC50 values of 1.8 +/- 0.2 microM, 1.9 +/- 0.4 microM and 4.3 +/- 1.7 microM, respectively. The EC50 values and the amplitude of maximal responses were not significantly different from one another. Clonidine (0.1-500 microM), a selective alpha 2-adrenoceptor agonist, was not effective. 4. Prazosin (0.1-9 microM), competitively antagonized the contractile effects of noradrenaline with an estimated pA2 value of 6.93 and a slope of 1.07 +/- 0.03. The Kb values, estimated from a single shift (0.1 microM prazosin) of the concentration-response curves to noradrenaline, adrenaline and phenylephrine were 92.8 +/- 9.3 nM, 108.7 +/- 6.4 nM and 18.4 +/- 3.1 nM, respectively. 5. At resting tension, adenosine 5' triphosphate (ATP, 5-1000 microM), alpha,beta-methylene adenosine 5'-triphosphate (alpha,beta-MeATP, 0.05-50 microM), beta,gamma-methylene adenosine 5'-triphosphate (beta,gamma-MeATP, 0.5-100 microM), and 2-methylthioadenosine 5'-triphosphate (2-MeSATP, 1-500 microM) caused concentration-dependent contractions with EC50 values of 60.5 +/- 15.9 microM, 0.7 +/- 0.1 microM, 7.6 +/- 0.1 microM and 25.3 +/- 12.8 microM, respectively. The maximal responses to alpha, beta-MeATP and beta,gamma-MeATP were greater than maximal responses to 2-MeSATP and ATP.6. Suramin (50-500 microM), competitively antagonized the contractile responses of alpha,beta-MeATP with an estimated pA2 value of 4.92 and a slope of 1.08 +/- 0.04. The Kb values, estimated from a single shift(1I00 microM suramin) of the concentration-response curves to ATP, alpha,beta-MeATP, beta,gamma-MeATP and 2MeSATPwere 52.3 +/- 20.2 microM, 25.2 +/- 4.5 microM, 21.7 +/- 11.0 microM and 11.6 +/- 2.7 microM, respectively.7. At resting tension, reactive blue 2 (100 microM), a selective antagonist of the P2Y-purinoceptor, and 8-(p-sulphophenyl)-theophylline (8-SPT) (1 microM), a selective antagonist of the PI-purinoceptor, did not antagonize the contractile responses to alpha,beta-MeATP (0.5-5 microM). Contractile responses to ATP(50-500 microM) were not altered by 8-SPT (I microM) but were potentiated by reactive blue 2 (100 microM).8. With raised tone, ATP and 2-MeSATP caused a relaxant effect. This effect of ATP was not altered by either tetrodotoxin (TTX) (0.5 microM) or suramin (100 microM), but was antagonized by reactive blue 2(100 microM) and 8-SPT (1 microM), suggesting that inhibitory P2y- and P1-purinoceptors are involved. In contrast, alpha,beta-MeATP and Beta,gamma-MeATP caused only contractions. This contractile effect of alpha,beta-MeATPwas resistant to TTX (0.5 microM) and antagonized by suramin (100 microM).9. In summary, cat colon circular muscle contains postjunctional alpha 1-adrenoceptors and P2X purinoceptors which mediate contractions and P2y- and PI-purinoceptors which mediate relaxation.Postjunctional alpha2-adrenoceptors appear not to be present.

Adenosine Triphosphate↗
PubMed1993

Liver function of hepatitis B carriers in childhood.

This study followed 314 children who were carriers of hepatitis B virus for 2 to 4 years and compared them with noncarriers, matched for age and sex, from the same community. No confirmed carrier lost hepatitis B surface antigen. Hepatitis B e antigen (HBeAg) was lost at a rate of 10.6% per year; the rate of decay was not affected by age or gender. Liver enzymes were higher in HBeAg-positive than in HBeAg-negative carriers and loss of HBeAg was usually followed by return to values in the normal range. There was evidence, however, of persistent mild liver dysfunction in carriers even after development of antibody to HBeAg. Serum alanine aminotransferase concentrations above twice the upper limit of normal were observed in 7% of carriers on at least one occasion but persisted for more than 1 year in less than 1% and clinical manifestations were rare. The hepatitis B carrier state was uncomplicated during the course of this study. However, risks of subsequent serious disease in adult life may be significant and continued surveillance of carriers is important for individual protection and to determine adverse prognostic features.

Adolescent↗
PubMed1993

Invalidity from nonparallelism in a radioimmunoassay for erythropoietin accounted for by human serum antibodies to rabbit IgG.

An immunologic crossreactant of erythropoietin seemed to develop and persist in serum samples from a patient during treatment and remission of idiopathic aplastic anemia. It had a steeper slope to radioimmunoassay log-dose response lines and a larger molecular size than erythropoietin. On fractionation of serum, the apparent crossreactant was bound by staphylococcal Protein A at pH 7.5 and recovered by elution from it at pH 3.0. Adsorption of serum from the patient, and from one of two similarly affected children, with rabbit IgG linked to agarose appeared to remove completely the apparent crossreactant. These treated sera gave radioimmunoassay log-dose response lines essentially parallel to that given by the International Reference Preparation (IRP) for erythropoietin and estimates of immunoreactive erythropoietin appropriate to the normal hemoglobin concentrations. The apparent crossreactant of erythropoietin is thus accounted for by heterophilic antibodies to rabbit IgG. These developed in the patient following treatment with rabbit antilymphocyte globulin but seem to have arisen spontaneously in the children. Thus iatrogenic and idiopathic antibodies to rabbit IgG interfered in a radioimmunoassay for erythropoietin in serum through their ability to react with the radioimmunoassay anti-erythropoietin antiserum raised in rabbits.

Adult↗
PubMed1992

Hepatitis B vaccination in children: five year booster study.

AIM: to demonstrate that appropriate doses of hepatitis B vaccines would be protective for at least five years in children. This would be shown by administering booster doses and measuring the response. METHODS: 2 micrograms intramuscular (IM) doses of Merck Sharp and Dohme (MSD) recombinant DNA vaccine (rDNAV) were given to 318 children who had received age appropriate doses of MSD plasma derived vaccine (PDV) five years earlier. Sera were tested for hepatitis B virus (HBV) seromarkers pre- and postbooster. RESULTS: all children who had responsed to primary immunisation demonstrated an anamnestic response. The geometric mean titre (GMT) of antibody to hepatitis B surface antigen (antiHBs) rose from 89 to 4777 IU/L. AntiHBs was detected in 94% of vaccinees just prior to the five year booster, and 96.5% a mean of 10 days later. CONCLUSION: when initial vaccine seroconversion is satisfactory, protection of responders persists for at least five years, assuming that the response to vaccine boosters mimics the response to wild virus. Therefore, for population control of hepatitis B in children in endemic areas, booster doses are not required for at least five years.

Antibodies, Viral↗
PubMed1992

Hemispheric interactions: the bilateral advantage and task difficulty.

Twenty-five normal subjects made "same-different" responses to dot patterns presented in the LVF, RVF or bilaterally. Task difficulty was manipulated in each condition by varying the number of dots in the two patterns presented from two to four to six. The pairs of patterns always had the same number of dots on a given trial. Response latency and accuracy worsened as the number of dots increased for all three presentation conditions and for both "same" and "different" judgements. Overall, responding was faster and the number of errors lower on Bilateral presentations. For response latencies to identical patterns of dots, the size of the bilateral advantage increased relative to RVF responding as task difficulty increased but did not change significantly relative to LVF responding. When the two patterns were not identical the size of the advantage did not change as task difficulty increased. "Same" judgements were faster but less accurate than "different" judgements. A model of hemispheric interactions is proposed to account for the findings.

Adult↗
PubMed1992

Serum immunoreactive erythropoietin in patients with idiopathic aplastic and Fanconi's anaemias.

In patients with idiopathic aplastic anaemia (n = 34) and Fanconi's anaemia (n = 8), sampled once or on several occasions, serum erythropoietin (Epo) increased with increasing severity of anaemia with apparently similar rates of increase in each group. However, after adjustment for Hb, log Epo values for the Fanconi's anaemics tended to be greater than those for the idiopathic aplastic anaemics (P < 0.01). Erythropoietin concentrations in serum samples from patients with Fanconi's and idiopathic aplastic anaemias tended to be greater than in samples from patients with anaemias from protein energy malnutrition, myelodysplasia and iron deficiency. The results suggest that there is no deficiency of erythropoietin in Fanconi's and idiopathic aplastic anaemias and that if exogenous erythropoietin is of any benefit it would need to be administered in doses large enough to induce a significant increase in log Epo. Results of the study illustrate the need to take account of the assumptions which underlie interpretation of the statistical analysis. Use of erythropoietin values in place of log Epo gives misleading conclusions demonstrable as invalid as the conditions for normality of distribution of the data and homogeneity of variances were not satisfied.

Adolescent↗
PubMed1991

Seroepidemiology of hepatitis B infection in children in Vanuatu. Implications for vaccination strategy.

Four hundred and eighty-two unvaccinated children from three different age groups (12-18 months, 30-42 months, 54-115 months) in a hepatitis B virus (HBV) endemic area were tested for markers of HBV infection. HBV seromarkers were detected in 52.3% of children and 26.9% were hepatitis B surface antigen (HBsAg) positive. Evidence of infection was related to age, with HBV seromarker rates highest (67.5%) in school children aged 56-115 months. The HBsAg positive rate was highest (30.1%) in children 30-42 months of age. However, even children in the youngest age group (12-18 months) had high seromarker (26.8%) and HBsAg positive (17.0%) rates. A high proportion of HBsAg positive children (83.8%) were also hepatitis Be antigen (HBeAg) positive. Mothers of children in the youngest age group (12-18 months) were also tested, and 24.5% were HBsAg positive. Factors associated with higher rates of infection in children included maternal HBeAg positivity (for children in the youngest age group), increasing age, and residence on the islands of Emao or Nguna. Higher rates of HBsAg positivity were associated with these factors and with being male. Crossinfection between children is probably the most important source of infection, based on the evidence of the high rate of HBeAg positivity in children and the rising infection rate with age. A possible vehicle of spread is through skin infections and skin sores which are highly prevalent in children in Vanuatu. Since this study indicates that both perinatal and early child-to-child transmission are occurring, the most practical strategy to prevent the majority of infections is to vaccinate all children, commencing at birth and completing the course early in the first year of life.

Child↗
PubMed1991

Updating one's knowledge about the current status of vehicles in a freight system simulation.

The use of simulations of real-world settings can provide data relevant to ergonomics problems in a wide range of similar settings. This paper reports on a simulation of a freight service operation. It examines the effect of manipulating the type and format of information representation on the ability to update knowledge about the status of three vehicles. In addition, the effects of display type and the detection of violations of pre-learned rules on the ability to update are examined. The display format proved not to be a critical factor but the requirement to detect rule violations of a specific vehicle resulted in better memory-updating performance for that vehicle. The results are discussed in terms of a human memory mechanism, which is analogous to a computer operating system, involved in updating memory and detecting violations. Finally, the value of using this tool to examine complex cognitive processes relevant to the workplace is discussed.

Journal Article↗
PubMed1991

Detection of Helicobacter pylori infection of the gastric mucosa by measurement of gastric aspirate ammonium and urea concentrations.

Helicobacter pylori possesses unusually high urease activity that lowers the urea concentration and raises the ammonium concentration of the gastric juice in infected people. The value of measuring urea and ammonium concentrations in gastric juice obtained during upper gastrointestinal endoscopy as a means of diagnosing the presence and eradication of the infection was assessed. Twenty four subjects with the infection and 14 in whom it had been eradicated were examined. Their H pylori status was confirmed by antral biopsy and 14C urea breath test. The median (range) gastric juice urea concentration in infected subjects was 0.8 mmol/l (0.5-2.9 mmol/l), which was lower than that in the uninfected subjects (2.1 mmol/l (1.0-3.7 mmol/l)) (p less than 0.001). The median gastric juice ammonium concentration in infected subjects was 3.4 mmol/l (1.0-13.0 mmol/l), which was higher than that in the uninfected subjects (0.64 mmol/l (0.02-1.4 mmol/l)) (p less than 0.001). Though the two groups overlapped in respect of their urea and ammonium concentrations, they were completely different when the urea: ammonium ratios were calculated--the ratios ranged from 0.04-0.7 (median 0.26) and from 1.1-113 (median 3.4) in infected and uninfected subjects respectively (p less than 0.001). Treatment with H2 antagonists did not change the concentrations of urea and ammonium or their ratio in gastric juice. Measurement of the urea: ammonium ratio in aspirated gastric juice obtained during routine upper gastrointestinal endoscopy may provide a rapid method of detecting H pylori infection and of confirming its eradication.

Adolescent↗
PubMed1990

Hepatitis B vaccine boosters: further studies in children.

Two groups of children were given reduced dose boosters with Merck Sharp and Dohme (MSD) recombinant DNa, yeast derived hepatitis B vaccine (YDV), 30 and 34 months respectively after primary immunisation with MSD plasma derived vaccine (PDV). In the first group of unselected children the geometric mean titre (GMT) rose from 387 to 8346 IU/L, with all children protected. The second group were selected as the poorest responders to their primary course of vaccine. The booster raised the GMT from 14.6 to 325 IU/L, with 95% having protective levels of anti-HBs (greater than 10 IU/L). This study confirms that the vaccine used by the New Zealand Department of Health for the hepatitis B immunisation programme in preschoolers, will provide protection for the great majority of children for at least three years.

Adolescent↗
PubMed1990

Very low dose hepatitis B vaccination in the newborn: anamnestic response to booster at four years.

Seventy-eight children who had received three very low doses (1 or 2 microg) of Merck, Sharp and Dohme (MSD) plasma-derived vaccine (PDV) in early infancy were followed to approximately four years of age. Of the 70 who had responded to the initial course of vaccine with measurable anti-HBs, levels had fallen to below 10 mlU/ml in 38% of subjects given 1 microg doses and in 17% of those who had been given 2 microg doses. None of the children were positive for anti-HBc. Two weeks after 2 microg dose of MSD recombinant DNA (rDNA) vaccine all subjects had more than 10 mlU/ml of anti-HBs, with 90% exceeding 1,000 mlU/ml. A response to hepatitis B vaccine in infancy is followed by an effective immunological memory for several years, even if anti-HBs falls to low levels. The rDNA hepatitis B vaccine (MSD) in 2 microg doses is an effective booster following a primary course of plasma derived vaccine.

Child, Preschool↗
PubMed1989

Mass vaccination against hepatitis B in preschool children: immunogenicity after three reduced doses.

The immunising effect of three reduced doses of Merck Sharp and Dohme (MSD) H-B Vax plasma derived vaccine delivered at monthly intervals was evaluated in 1225 four year old children. Eighteen children had evidence of previous or current infection with HBV. Of the remaining 1207 children, 1186 (98.3%) had antibody to hepatitis B surface antigen (anti-HBs) when tested by enzyme immunoassay (EIA). Levels of anti-HBs in 96 randomly selected sera were independently quantitated by radioimmunoassay (RIA) and all were positive for anti-HBs, with a geometric mean titre of 1013. There was no significant difference in seroconversion or anti-HBs levels between the groups of children nationwide. In 19 of the 39 centres, seroconversion was 100%. No centre had less than 92% seroconversion. This study confirms that three 2 microgram doses of MSD H-B Vax plasma derived vaccine given intramuscularly (IM) at monthly intervals are highly immunogenic in this paediatric population.

Child, Preschool↗