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Biomedical subjects

N J Bell

Publications and source records attributed to N J Bell.

At least 19 recordsLinked to original sources
PubMed2006

Herd health planning: farmers' perceptions in relation to lameness and mastitis.

Between December 2002 and December 2003, the herd health planning activities on 61 dairy farms in the uk were compared with several measures of lameness and mastitis. Lameness had been reported as a problem in 53 of the herds directly by the farm and in the other eight by the nominating local veterinary practice; 54 of the farms also reported having a mastitis problem. Fifty-three (87 per cent) of the farms had some form of written herd health plan, of which 21 (40 per cent) had been in place for 12 months or less. All the farms were recording mastitis in some way, although 38 (62 per cent) of the farmers did not review these records and only four retained the results of a comprehensive record review. Farms defined as having a high incidence of mastitis were more likely to be reviewing their health records, but farms defined as having a high prevalence of lameness in a sentinel group of early lactation heifers were less likely to be reviewing their health records.

Animal Welfare↗
PubMed2003

Neurokinin B is a paracrine vasodilator in the human fetal placental circulation.

Neurokinin (NK) B is a member of the tachykinin family of neurotransmitters, exerting hypotensive or hypertensive effects in the mammalian vasculature through synaptic release from peripheral neurons, according to either NK(1) and NK(2) or NK(3) receptor subtype expression, respectively. There is recent evidence that NKB is expressed by the syncytiotrophoblast of the human placenta, an organ that is not innervated. We hypothesized that NKB is a paracrine modulator of tone in the fetal placental circulation. We tested this hypothesis using the in vitro perfused human placental cotyledon. Our data show that NKB is a dilator of the fetal vasculature, causing a maximal 25.1 +/- 4.5% (mean +/- SEM; n = 5) decrease in fetal-side arterial hydrostatic pressure (5- microM NKB bolus; effective concentration in the circulation, 1.89 nM) after preconstriction with U-46619. RT-PCR demonstrated the presence of mRNA for NK(1) and NK(2) tachykinin receptors in the placenta. Using selective receptor antagonists, we found that NKB-induced vasodilation is through the NK(1) receptor subtype. We found no evidence for the involvement of either nitric oxide or prostacyclin in this response. This study demonstrates a paracrine role for NKB in the regulation of fetal placental vascular tone.

Blood Pressure↗
PubMed2000

Attachment, adolescent competencies, and substance use: developmental considerations in the study of risk behaviors.

Social-control-based deviance theories highlight parental bonding as a protective factor for problem behaviors in that bonds are viewed as reflecting the adolescent's adoption of conventional societal attitudes and values. Developmental theory and research suggest an alternative conceptualization of the linkages between family bonding and adolescent risk behaviors. This conceptualization requires concurrent examination of a range of adolescent competencies as well as consideration of parent and peer contexts. Support is found for several hypotheses derived from a developmental approach proposing: (a) positive associations between adolescent-parent attachment and adolescent competencies--autonomy, peer relationship competency, and coping; (b) coherence in the pattern of negative associations between attachment/competencies and substance use problems; and (c) a disjunctive pattern of associations with substance use reflected by positive associations with peer competencies but not with parental attachment.

Adaptation, Psychological↗
PubMed1999

Family correlates of adolescent self-monitoring and social competence.

The purpose of this study was to investigate linkages between adolescent self-monitoring, global social competence, and parenting and family environment dimensions of support and encouragement of autonomy. The sample consisted of 233 young women and 199 young men at 2 southwestern universities. The primary measures used were the Family Environment Scale (R. H. Moos, 1981), the Parent Behavior Form (L. Worell & J. Worell, 1974), the revised Self-Monitoring Scale (M. Snyder, 1987), and the Texas Social Behavior Inventory (R. Helmreich, J. Stapp, & C. Ervin, 1974). Findings indicated that family variables are more strongly associated with social competence than with self-monitoring; family support was, overall, a more important ingredient of social competence than was autonomy. Women and men had different patterns of associations among specific variables.

Adolescent↗
PubMed1996

Time to maximum effect of lansoprazole on gastric pH in normal male volunteers.

BACKGROUND: The time to maximum inhibition of gastric acidity resulting from repeated oral dosing with lansoprazole 30 mg daily for 7 days was studied in nine healthy male volunteers. METHODS: Twenty-four hour intragastric pH monitoring was performed before treatment and on days 1, 3, 5 and 7 of dosing with lansoprazole. Blood samples were taken for the estimation of plasma lansoprazole concentrations. RESULTS: Lansoprazole 30 mg increased mean 24-h intragastric pH to 3.57 on day 1 compared with baseline mean pH of 2.11 (P < 0.05). The mean intragastric pH during the morning period (08.00-13.00 h) was significantly higher on days 3, 5 and 7 than on day 1, but no consistent differences between day 1, 3, 5 and 7 were noted for subsequent periods (13.00-18.00, 18.00-21.00 and 23.00-07.00 h). There were no differences in mean pH between days 3, 5 and 7. Intragastric pH was maintained above pH 3 for 54.7, 60.1, 61.9 and 67.4% of the time on days 1, 3, 5 and 7, respectively. Lansoprazole pharmacokinetic parameters did not change with daily dosing. The area under the lansoprazole plasma concentration-time curve correlated with the intragastric pH (P < 0.005). CONCLUSIONS: Lansoprazole 30 mg raised intragastric pH significantly from baseline on day 1 to a maximum effect as early as 6 h after the first dose. The degree and duration of acid suppression confirm the usefulness of lansoprazole for the treatment of acid-related disorders.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1994

P2 purinoceptor antagonist properties of pyridoxal-5-phosphate.

The antagonist properties of pyridoxal-5-phosphate, a synthesis precursor of pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid, were investigated on P2 purinoceptor-mediated responses of the rat isolated vagus nerve and vas deferens. In addition, the effect of this agent was studied on high affinity tritiated alpha,beta-methylene adenosine triphosphate (alpha,beta-meATP) binding to rat vas deferens membranes, thought to represent binding to functional P2x purinoceptors. In the rat vagus nerve, pyridoxal-5-phosphate (10(-5)-10(-4) M) produced concentration-related antagonism of depolarisation responses induced by alpha,beta-meATP, measured using an extracellular recording technique. In contrast, depolarisation responses to 5-hydroxytryptamine (5-HT) were unaffected by pyridoxal-5-phosphate. In the rat vas deferens, pyridoxal-5-phosphate (10(-5)-10(-4) M) antagonised contractile responses produced by alpha,beta-meATP while contractions to phenylephrine were unaffected. However, responses of the vagus nerve and the vas deferens to alpha,beta-meATP were not antagonised by pyridoxal hydrochloride (10(-4) M). Pyridoxal-5-phosphate competed for high affinity binding of [3H]alpha,beta-meATP to homogenised membranes of the rat vas deferens with a pKi estimate of 4.91 +/- 0.12 and a Hill slope of 0.80 +/- 0.03. Pyridoxal hydrochloride only competed for binding at concentrations in excess of 10(-4) M, yielding a pKi estimate of 3.21 +/- 0.04 and a Hill slope of 1.82 +/- 0.12. These findings indicate that pyridoxal-5-phosphate acts as a specific antagonist of P2 purinoceptors in the vagus nerve and vas deferens of the rat and that the phosphate moiety is required for activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1994

Effects of divalent cations on the potency of ATP and related agonists in the rat isolated vagus nerve: implications for P2 purinoceptor classification.

1. By use of a 'grease-gap' technique, the depolarizing effects of adenosine 5'-triphosphate (ATP) and ATP analogues on the rat isolated vagus nerve were determined in normal and in Ca2+/Mg(2+)-free (+ 1 x 10(-3) M ethylenediamine tetraacetic acid) physiological salt solution (PSS). 2. In normal PSS, ATP produced concentration-dependent depolarization responses but the concentration-effect curve to ATP was incomplete and a maximum effect was not achieved. The threshold concentration for depolarization was 1 x 10(-5) M and at the highest concentration tested (1 x 10(-3) M) the peak amplitude of the response to ATP only amounted to 71% of the depolarization produced by a near maximal response to 5-hydroxytryptamine (5-HT, 1 x 10(-5) M). 3. In Ca2+/Mg(2+)-free PSS, ATP produced depolarization responses at much lower concentrations and of markedly larger amplitude. Under these conditions, the threshold concentration for depolarization was 1-3 x 10(-7) M and the maximal response to ATP amounted to 526% of the response to 5-HT (1 x 10(-5) M) in normal PSS. The concentration-effect curve to ATP was sigmoid, with a defined maximum effect and a mean EC50 value of 1.2 x 10(-6) M. 4. In contrast to the effects on responses to ATP, the absence of divalent cations in the PSS did not modify the effective concentrations of either alpha, beta-methylene ATP or 5-HT. However, the maximum responses to both alpha, beta-methylene ATP and 5-HT were significantly increased in Ca2+/Mg(2+)-free PSS. 5. The depolarizing effects of several analogues of ATP were determined in Ca2+/Mg2+-free PSS.ATP-gamma-S and 2-methylthioATP were of similar potency to ATP (respective equi-effective molar ratios(EMRs) of 1.9 and 1.3, where ATP = 1) and similar maximum responses were obtained. Alpha, beta-MethyleneATP, beta, gamma-methylene ATP and ,beta, gamma-imido ATP were considerably less potent than ATP, analysis yielding mean EMRs of 48.9, 85.0 and 60.0, respectively. Maximum responses to these latter three agonists were not obtained at the highest concentrations tested (1 x 10-4-3 X 10- M). Benzoyl ATP, adenosine 5'-0-(2-thiodiphosphate) and adenosine diphosphate produced only small depolarizing responses at high concentrations (>1 x 10-4 M). Adenosine monophosphate, adenosine and uridine S'-triphosphate each had little or no depolarizing effect in Ca2+/Mg2+-free PSS.6. These data demonstrate that in the absence of divalent cations the excitatory actions of some, but not all, purine nucleotides in the rat vagus nerve are markedly potentiated. In Ca2+/Mg2+-free PSS, the rank order of agonist potencies was ATP = 2-methylthioATP = ATP-gamma-S>> alpha,beta-methylene ATP = beta, gamma imido ATP = P,y-methylene ATP. These findings are in stark contrast to our previous observations in normal PSS where the rank order of agonist potencies for these nucleotides was alpha,beta-methyleneATP> ATP-gamma-S > beta,gamma-imido ATP = beta,gamma-methylene ATP> 2-methylthioATP> ATP.7. We suggest that the two different rank orders of potency can be explained by differential metabolism involving Ca2+/Mg2+-dependent ectonucleotidases. If so, these data indicate that ATP and 2-methylthioATP are inherently more potent than alpha,beta-methylene ATP as agonists at neuronal P2X purinoceptors in the rat vagus nerve. The possible implications of these findings to the present system for subclassifying P2 purinoceptors are profound.

Adenosine Triphosphate↗
PubMed1992

Role of gastric acid suppression in the treatment of gastro-oesophageal reflux disease.

Gastro-oesophageal reflux disease is a common condition with a complex pathophysiology. Despite the spectrum of abnormalities, gastric acid has a central role in mucosal damage, and the mainstay of medical treatment is suppression of gastric acid secretion. The results of antisecretory treatment as assessed by endoscopic healing are reviewed. H2 receptor antagonists give more rapid symptom relief than placebo and can produce endoscopic improvement in 31-88% of cases depending on the severity of oesophagitis. Complete healing, however, is seen only in 27-45% of patients and these have mainly grades I-II disease. Improved healing rates can be obtained by increasing the degree of acid suppression or the length of treatment. The addition of a prokinetic agent may be beneficial. Omeprazole heals 67-92% of patients overall and although most successful in the lower grades of oesophagitis, can also heal 48-62% of patients with grade IV disease. The degree and rate of healing seem to be related to the reduction in oesophageal acid exposure and thus may correlate with the degree and duration of acid suppression over 24 hours obtained by the various treatments. The underlying pathophysiology is unchanged, however, and long term treatment may be needed to maintain remission.

Gastric Acid↗
PubMed1992

Appropriate acid suppression for the management of gastro-oesophageal reflux disease.

Gastro-oesophageal reflux disease (GORD) results from an abnormally prolonged dwell time of acidic gastric contents in the oesophagus. Although GORD is primarily a motor disorder, the injurious effects of gastric acid are central to the pathogenic process of oesophagitis, and the severity of disease correlates with the degree and duration of oesophageal acid exposure. In the majority of patients with mild disease, oesophageal acid exposure occurs predominantly during post-prandial periods. Conventional doses of H2-receptor antagonists cannot overcome the integrated stimulus to acid secretion resulting from a meal, and are thus relatively ineffective in preventing daytime, post-prandial oesophageal acid exposure. In patients with more severe grades of oesophagitis, there are abnormally high levels of nocturnal acid exposure, with the intra-oesophageal pH being less than 4.0 for 36% of the time, compared with 5% of the time in patients with mild GORD. Control of nocturnal acid secretion thus becomes increasingly important. This may be made worse by relative gastric acid hypersecretion in some patients with severe GORD. The long duration of action and effective inhibition of meal-stimulated acid secretion probably explains the superiority of omeprazole in treating GORD. Preliminary meta-analysis shows that the healing rate of erosive oesophagitis at 8 weeks by antisecretory agents is directly related to the duration of suppression of gastric acid secretion achieved over a 24-hour period (r = 0.87; p less than 0.05).

Anti-Ulcer Agents↗
PubMed1986

Bronchoscopic cryotherapy for airway strictures caused by tumors.

This study reports an application of cryosurgery for the treatment of tracheobronchial tumors. Bronchoscopic cryotherapy can be applied in patients who are not candidates for other traditional therapy. The technique utilizes a nitrous oxide cryoprobe, introduced through a rigid bronchoscope. The principal feature of this probe is to be nonrigid. The cryodestruction is controlled by an impedance metric method. The study group consisted of 27 patients ranging in age from 39 to 88 years. The most frequent diagnosis was squamous cell carcinoma (14). For malignant tumors, the objective was obtained in 13 cases out of 21. Cryotherapy successfully destroyed five benign granulomas. Four or six days after cryotherapy, bronchial biopsy specimens usually showed a necrotic substance, and tumoral tissues were entirely destroyed. The time of survival is probably extended and the quality of life bettered. Most visible tumors are now reached with a flexible cryoprobe, inserted in a flexible bronchoscope.

Adenocarcinoma↗
PubMed1981

Change over time in the community: findings of a longitudinal study.

The findings of this study indicated that: a) the aspects of community functioning included in this study were relatively stable over a two-year period; b) when change did occur, it tended to be toward the end of the two-year period; c) ability level (basic skills) was related to community functioning more consistently than age, gender, or the environmental variables included in these analyses; d) relationships with ability were more frequent following approximately 10 months in the community than prior to that time; and e) there is a possibility that the time period around 10 months after entry into the community is a particularly difficult time and warrants further investigation.

Adolescent↗
PubMed1981

Adult reactions to children's cross-gender verbal behavior.

Reactions of teachers and college students were obtained to a child, labeled male or female, exhibiting stereotypically masculine or feminine verbal behavior. The findings were: (1) adults did not redirect or discourage cross-gender compared with gender-appropriate behavior; (2) adults rated same-sex children higher on a subset of masculine traits, regardless of the child's behavior; (3) adult females rated the child more positively and responded to the child in a more reinforcing manner than did males; (4) male teachers responded to the child more positively than nonteachers, but the reverse was true for females; (5) all adults reinforced feminine more than masculine behaviors; and (6) nonteachers were more attracted to the female child and the child exhibiting feminine behaviors, while teachers were more attracted to the male child and the child exhibiting masculine behaviors.

Adult↗
PubMed1978

Adults' perceptions of children's independence and other sex-role characteristics as a function of child's gender label.

Male and female college students were presented with a photograph labeled as a 5-yr.-old boy or girl and heard statements attributed to the child. They then rated the child on sex-role traits and responded to open-ended questions about the child. The primary findings involved sex of child by sex of adult interactions on ratings of independence and leadership: in both cases, same-sex children were rated higher than opposite-sex children. There was also some evidence that women having high contact with children rated the child more extremely on opposite-sex traits than did those with little contact.

Adolescent↗