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Biomedical subjects

A Davis

Publications and source records attributed to A Davis.

At least 253 records · Page 14Linked to original sources
PubMed1992

Induction of cholangiocarcinoma in the Golden Syrian hamster using methylazoxymethyl acetate.

The Golden Syrian hamster, which has a bile acid profile similar to that of humans, is often used as an experimental model for cholangiocarcinoma. Unfortunately, most chemical carcinogens result in other tumour types also being induced which can be disadvantageous. In the present study, we describe the development of cholangiocarcinoma associated with precursor lesions of bile duct proliferation and dysplasia which occurred following a single i.v. dose of methylazoxymethyl acetate (10, 20 or 40 mg/kg body weight). Moreover, no other tumours were induced. This model may, therefore, prove useful in investigating the steps involved in the carcinogenesis of cholangiocarcinoma.

Adenoma, Bile Duct↗
PubMed1992

Selective population chemotherapy among schoolchildren in Beheira governorate: the UNICEF/Arab Republic of Egypt/WHO Schistosomiasis Control Project.

Selective population chemotherapy using a single dose of praziquantel (40 mg per kg body weight), which was offered to 29,365 schoolchildren in Abu El Matameer and 40,241 in Abo Homos districts, Beheira governorate in the Nile delta, reduced the prevalence of schistosomiasis from 75.4% to 40.9% (reduction of 45.8%) and from 80.5% to 30.8% (reduction of 61.7%), respectively. Of those with only S. mansoni infection, 10.6% before treatment and 1.7% one year later had more than 800 eggs per gram of faeces. The prevalence of S. haematobium in Abu El Matameer was reduced from 35.4% to 7.4% after a single treatment. Infections with both S. mansoni and S. haematobium were reduced by more than 90% after one year. These reductions in prevalence and intensity of schistosomiasis in the face of continuing transmission and water contact augur well for the future role of chemotherapy in control programmes.

Adult↗
PubMed1992

Dentin phosphoprotein gene locus is not associated with dentinogenesis imperfecta types II and III.

Dentinogenesis imperfecta (DGI) is an autosomal dominant inherited dental disease which affects dentin production and mineralization. Genetic linkage studies have been performed on several multigeneration informative kindreds. These studies determined linkage between DGI type II and III and group-specific component (vitamin D-binding protein). This gene locus has been localized to the long arm of human chromosome 4 in the region 4q11-q21. Although this disease has been mapped to chromosome 4, the defective gene product is yet to be determined. Biochemical studies have suggested abnormal levels of dentin phosphoprotein (DPP) associated with DGI type II. This highly acidic protein is the major noncollagenous component of dentin, being solely expressed by the ectomesenchymal derived odontoblast cells of the tooth. The purpose of the present study was to establish whether DPP is associated with DGI types II and III, by using molecular biology techniques. The strategy was to use a synthetic degenerative DPP oligonucleotide probe to map this sequence to the long arm of human chromosome 4, 4q13-q21, by using somatic cell hybrids. Our results indicated that DPP is not localized to any region of human chromosome 4, thus suggesting that the DPP gene is not directly associated with DGI type II or DGI type III. Our data do not exclude the possibility that other proteins associated with DPP posttranslational modifications might be responsible for this genetic disease.

Adult↗
PubMed1991

Advocacy. Necessary to achieve cancer control goals.

As resources become increasingly scarce, oncology professionals and consumers of oncology services are increasingly engaging in advocacy efforts to achieve goals in cancer control. Effective advocacy includes both legislative and direct educational efforts.

Aged↗
PubMed1991

Superiority of granisetron to dexamethasone plus prochlorperazine in the prevention of chemotherapy-induced emesis.

Trials of selective 5-hydroxytryptamine3 receptor antagonists have shown excellent antiemetic activity for chemotherapy containing cisplatin when compared with high-dose metoclopramide. There is little information about the efficacy of these new agents for chemotherapy other than for high-dose cisplatin. We performed a double-blind, randomized trial comparing a single dose of the 5-hydroxytryptamine3 receptor antagonist granisetron (BRL 43694A) as a single intravenous dose with dexamethasone plus prochlorperazine in 152 patients receiving their first course of moderately emetogenic chemotherapy (mainly doxorubicin- and cyclophosphamide-containing combinations). During the first 24 hours, there was a statistically significant advantage for the granisetron group in terms of the prevention of both nausea and emesis. There was no difference in the frequency of reported adverse events. We conclude that granisetron is more effective than dexamethasone plus prochlorperazine in patients who are receiving moderately emetogenic cytotoxic agents.

Antiemetics↗
PubMed1991

Effect of rimantadine on the immune response to influenza A infections.

The effects of rimantadine on lymphocyte responses to mitogens CON-A and PHA, natural killer cell activity, and the development of serum and local antibodies were studied during an epidemic outbreak of influenza A (H3N2). Twenty-three families consisting of 38 adults and 46 children had a member who developed a flu-like illness and were randomly assigned to receive placebo or rimantadine either as treatment or post exposure prophylaxis. Nasal washings for virus isolation and IgG and IgA determination were collected on days 1, 5, and 10 of illness. Blood samples for immunologic studies were obtained on days 1 and 5 of clinical illness and on day 21. No differences in lymphocyte responses to CON-A and PHA or in natural-killer cell activity were noted between placebo and rimantadine groups. The development of neutralizing antibodies to influenza H3N2 was also not affected by rimantadine. However, the presence of IgA in nasal secretions was significantly diminished in the rimantadine group compared to the placebo group (0/9 vs. 6/9, P less than 0.005). The findings indicate that rimantadine had no adverse affect on the systemic immune system. However, local immune response was diminished in individuals taking rimantadine possibly due to the presence of less immunogen resulting from reduction of virus in secretions of individuals taking antivirals.

Antibody Formation↗
PubMed1991

Functional outcome in patients treated with surgery and irradiation for soft tissue tumours.

One hundred five consecutive patients underwent surgical resection and adjuvant irradiation in treatment of soft tissue sarcoma or aggressive fibromatosis. All patients were entered in a prospective study evaluating functional outcome and 88 patients were examined at 12 months following surgery. Outcome was characterized using the Enneking system as well as documenting employment/recreational status and limb edema. Sixty-eight of 88 patients had functional scores of 21 or better (out of a possible total of 35). Forty-four patients were serially evaluated at 12 and 24 months and there was no difference in their outcome at the 2 time points. Univariate analysis demonstrated that large tumour size, postoperative complications, and neural sacrifice were associated with poor functional outcome.

Adolescent↗
PubMed1991

A double-blind comparison of granisetron and placebo for the treatment of acute migraine in the emergency department.

Three hundred and ninety-seven patients who presented to the emergency department were screened for a randomized, double-blind, placebo-controlled study of iv granisetron (40 micrograms/kg or 80 micrograms/kg) in acute migraine. Twenty-eight patients fulfilled the stringent eligibility criteria and completed the study. Rescue medication was required 2 h post-infusion in 8 of 10 patients receiving granisetron 40 micrograms/kg, 5 of 10 patients receiving granisetron 80 micrograms/kg, and 6 of 8 patients receiving placebo. Significant improvement (p less than 0.05) in headache pain (on a visual analogue scale and categorical scale) was observed in the 80-micrograms/kg group. Headache pain evaluated with the Hunter headache scale indicated improvement for the sensory and affective components of headache pain in both granisetron groups. Except for more nausea at 30 min in the placebo group, no significant differences were noted between treatments. All three treatments were well tolerated. Granisetron may be effective for acute migraine headache; however, further studies with increased patient numbers are required.

Acute Disease↗
PubMed1991

Effects of the potassium channel activator, cromakalim, on arterial and cardiac responses to norepinephrine, angiotensin II, and isoproterenol in normotensive men.

Cromakalim relaxes vascular smooth muscle by increasing potassium channel conductance, thus hyperpolarizing cell membranes. Its interactions in humans with the cardiovascular effects of norepinephrine, angiotensin II, and isoproterenol were investigated. Eight young normotensive male volunteers received on three different study days, 7-14 days apart, placebo, cromakalim at 1 mg, or cromakalim at 2 mg in a single oral dose, followed 2 h later by incremental intravenous doses of norepinephrine, angiotensin II, and isoproterenol. The diastolic blood pressure and total peripheral resistance (TPR) did not decrease significantly, but significant positive inotropic and chronotropic responses were noted after cromakalim. Cromakalim, both at 1 and 2 mg, blunted (p less than 0.05) the increase in TPR induced by norepinephrine, but did not interfere with its positive inotropic effect (P/V ratio). During angiotensin II infusion, TPR was also lower on both doses of cromakalim (p less than 0.05). Cardiac effects and aldosterone release were not affected. Cromakalim blunted the peripheral vasodilation induced by beta-receptor stimulation by isoproterenol, but did not affect the cardiac stimulation. The potassium channel activator, cromakalim, therefore antagonized the changes in TPR induced by norepinephrine, angiotensin II, and isoproterenol, but did not interfere with the cardiac responses, suggesting selectivity for arterial smooth muscle.

Adult↗
PubMed1991

Acceptability of binaural hearing aids: a cross-over study.

Using screening questionnaires we were able to detect individuals aged 50-65 years with hearing disability in a general practice population. Those who had better ear hearing levels of 30 dB or worse were invited to take place in a cross-over study comparing the acceptability of a monaural or binaural hearing-aid fitting. Fifty-five per cent ultimately opted for a binaural fitting and had greater hearing disability and worse mean hearing levels than those who opted for a monaural fitting. They made their choice for acoustical reasons, particularly on the basis of improved localization ability.

Audiometry↗
PubMed1991

The influence of health insurance status on the organisation of patient care in Sydney public hospitals.

Utilising intensive semi-structured interviews with health professionals working in public hospitals in Sydney, a comparison was made of the perceived similarities and differences in the medical and administrative management of patients who were covered by Medicare and those who were privately insured. Interviewees argued that there was evidence of preferential access to public hospital care for privately insured patients due to medical misrepresentation of the urgency of their cases. They reported that some medical and administrative practices existed which compromised the choice of admission as a Medicare patient for those with private insurance, and for those without private insurance who were referred to hospital by a specialist. It was suggested also by the interviewees that medical considerations encouraged continuity of specialist care for Medicare patients admitted to hospital when they were known to an attending specialist. Such an allegation places in some doubt the claim made by private insurers that choice of doctor is permitted only under their cover. Interviewees did not report knowledge of any form of compromise in the quality of hospital care on the basis of medical preference for private patients. However, it was reported that private patients may, in some instances, be denied a full range of hospital services due to doctors' attempts to monopolise their treatment.

Continuity of Patient Care↗
PubMed1990

Assisted death.

Explore the source record for details and available documents.

Persons with Disabilities↗
PubMed1990

Differential ability of selective and non-selective dopamine agonists to induce climbing in the rat indicates the involvement of both D-1 and D-2 receptors in this behaviour.

Approximately 50% of female Wistar rats examined exhibited a continuous climbing response to a screening dose of apomorphine. In animals identified as climbing, the mixed D-1/D-2 agonists apomorphine, pergolide and L-dopa, and the indirectly acting agonists nomifensine and (+)-amphetamine, induced a dose-related climbing response. The selective D-1 agonist SKF 38393 caused only minimal climbing, and the selective D-2 agonists bromocriptine, lisuride and LY 141865 induced a weak climbing response. All agonists examined, except SKF 38393, caused a dose-related stereotypy response. The selective D-1 antagonist SCH 23390, and the selective D-2 antagonist sulpiride, both produced maximum inhibition of apomorphine-induced climbing. SCH 23390 also inhibited stereotyped behaviour, but sulpiride was less effective. In animals identified as "non-climbers" using the screening dose of apomorphine, only L-dopa induced a marked climbing response. Nomifensine and bromocriptine produced weak or discontinuous climbing in this group, while the other agonists examined had little or no effect. In contrast all drugs examined, except SKF 38393, induced stereotyped behaviour of the same intensity observed in the "climbers". It is concluded that stimulation of both D-1 and D-2 receptors is necessary to induce a continuous climbing behaviour in rats. D-2, but not D-1 stimulation, alone can induce a weak or discontinuous climbing response, but concomitant stimulation of D-1 receptors potentiates this effect. Failure of some rats to climb does not appear to be related to relative degrees of D-1 and D-2 stimulation.

Amphetamine↗
PubMed1990

Simple disturbance of the dam in the neonatal period can alter haloperidol-induced catalepsy in the adult offspring.

Three experiments were performed to determine whether apparently minimal disturbances of dams and litters would influence haloperidol-induced akinesia. In Experiment I, Long-Evans hooded rats (a) were left unmanipulated, (b) received nestcage relocation and observation, (c) received nestcage relocation/observation and maternal separation, or (d) received nestcage relocation/observation and pup handling. The male adult offspring received open-field testing and later received forepaw-on-dowel catalepsy testing following saline, morphine (20 mg/kg), or haloperidol (2 mg/kg). In Experiment II, hooded rats received (a) no manipulation, (b) nestcage relocation, (c) maternal separation, or (d) pup handling. At weaning, dams were tested in the open-field. Activity wheel locomotion of the offspring was assessed following saline or haloperidol for 3 days/week for 3 weeks; then, 5 and 7 days later, rats received haloperidol (0.5 mg/kg) and catalepsy testing. In both experiments, manipulations involving the dam reduced the offsprings' haloperidol-induced catalepsy, but, in Experiment II, a history of haloperidol administration distinguished between the effects of nestcage relocation and maternal separation. In Experiment III, Swiss albino mice received (a) no treatment, (b) nestcage relocation and maternal separation, (c) relocation/separation and mild cold stress of pups, (d) relocation/separation and pup handling, or (e) relocation/separation and severe cold stress of pups. Adult male mice received saline or haloperidol (2.5 mg/kg) and inclined grid catalepsy testing. Mice receiving relocation/separation and mice receiving relocation/separation and severe cold stress showed enhanced catalepsy versus control mice. Thus, it was concluded that seemingly innocuous events in infancy can influence the intensity of extrapyramidal side effects of neuroleptics in adulthood.

Animals↗
PubMed1990

Allograft-implant composite reconstruction following periacetabular sarcoma resection.

Ten patients with primary periacetabular sarcomas were treated with internal hemipelvectomy and allograft-implant composite reconstruction. Three patients developed local recurrences, one of which was salvaged with repeat resection. One patient underwent hemipelvectomy for infected wound recurrence. At a mean follow-up period of 25 months (range, 7-85 months; median, 18 months), six of nine patients assessed with the Musculoskeletal Tumor Society functional assessment had satisfactory results, with scores of 21 or better (of a possible 35). Although complications were frequent and functional scores were often limited by the muscle resection required for adequate tumor removal, we remain cautiously optimistic about the early results of this procedure.

Acetabulum↗