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Biomedical subjects

H Reid

Publications and source records attributed to H Reid.

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

The epidemiology of louping-ill, a tick borne infection of red grouse (Lagopus lagopus scoticus).

The epidemiology of louping-ill in red grouse was studied in northern Britain concentrating on the possible role of other species and mechanisms of disease persistence. This tick borne viral disease caused heavy mortality in red grouse, particularly chicks. Louping-ill induced mortality reduced the strength of the density dependence that generates the tendency of grouse populations to cycle and in some populations may cause population sinks. Four routes of transmission were examined and non-viraemic transmission of virus between ticks cofeeding on hares was considered significant. Field data supported the hypothesis that disease dynamics is influenced greatly by mountain hares, both as passive amplifiers and as hosts for the tick vector. Genetic variation in louping-ill within Britain was small.

Animals↗
PubMed1996

Cytokines and their inhibitors in orf virus infection.

The epitheliotropic parapoxvirus, orf virus, can repeatedly infect sheep skin. A specific immune response is generated as reinfections induce smaller lesions with quicker resolution times than primary lesions. Cyclosporin-A treatment abrogates this partial immunity. Cytokine mRNAs detected in lesion biopsies include the transcripts for IL-1 beta, IL-3 GM-CSF, TNF-alpha and, less reproducibly, IFN-gamma. CD4+ T-cells predominate in afferent lymph draining the site of infection, and are the major source of GM-CSF and IFN-gamma. IL-1 beta and IL-8 are also detected. The orf virus genome contains a homologue of mammalian vascular endothelial growth factor that may enhance virulence and a vaccinia virus E3L-like gene which may inhibit the anti-viral effect of the interferons. A GM-CSF inhibitory activity has also been discovered and has been 'chased' into a 10 kb DNA segment of the orf virus genome. These studies indicate that orf virus may temporarily avoid host immunity by a combination of acute, rapid infection and replication in the epidermis and by producing virulence factors that inhibit protective proteins of the host immune and inflammatory response.

Animals↗
PubMed1996

Inter- and intracellular heterogeneity of O6-alkylguanine-DNA alkyltransferase expression in human brain tumors: possible significance in nitrosourea therapy.

The inter- and intracellular distribution of the DNA repair protein O6-alkylguanine-DNA alkyltransferase (ATase) may be an important factor in the sensitivity or resistance of tumours to treatment with certain alkylating agents, including the methyltriazenes and nitrosoureas. In order to examine this issue 26 human brain tumour sections (23 high grade gliomas and three low grade gliomas) were examined for ATase expression by immunohistochemistry using a rabbit anti-human ATase polyclonal antibody. Positive staining, seen as fine black granules mainly confined to the nucleus, was observed in all the glioma sections examined. There was marked cellular heterogeneity, ranging from cells completely devoid of staining to cells with very intense staining. Semi-quantitatively, in the 23 high grade gliomas examined six had 1+ staining, seven had 2+ staining and 10 had 3+ staining, whereas all three low grade gliomas had 1+ staining. These results are in contrast to published reports showing that approximately 35% of human brain tumour-derived cell lines and xenografts had very low levels of ATase activity and suggest that the complete lack of ATase is not a common occurrence in high grade glioma.

Antineoplastic Agents, Alkylating↗
PubMed1995

Persistence and transmission of tick-borne viruses: Ixodes ricinus and louping-ill virus in red grouse populations.

The population dynamics of tick-borne disease agents and in particular the mechanisms which influence their persistence are examined with reference to the flavivirus that causes louping-ill in red grouse and sheep. Pockets of infection cause heavy mortality and the infection probably persists as a consequence of immigration of susceptible hosts. Seroprevalence is positively associated with temporal variations in vectors per host, although variation between areas is associated with the abundance of mountain hares. The presence of alternative tick hosts, particularly large mammals, provides additional hosts for increasing tick abundance. Grouse alone can not support the vectors and the pathogen but both can persist when a non-viraemic mammalian host supports the tick population and a sufficiently high number of nymphs bite grouse. These alternative hosts may also amplify virus through non-viraemic transmission by the process of co-feeding, although the relative significance of this has yet to be determined. Another possible route of infection is through the ingestion of vectors when feeding or preening. Trans-ovarial transmission is a potentially important mechanism for virus persistence but has not been recorded with louping-ill and Ixodes ricinus. The influence of non-viraemic hosts, both in the multiplication of vectors and the amplification of virus through non-viraemic transmission are considered significant for virus persistence.

Animals↗
PubMed1995

Predicting patterns of sexual acts among homosexual and bisexual youths.

OBJECTIVE: This longitudinal study examined predictors of patterns of change in HIV sexual risk acts among homosexual and bisexual adolescent males. METHOD: A consecutive series of 136 homosexual and bisexual males aged 14-19 years were recruited into the study. Subjects were predominantly Hispanic (51%) and African American (31%) and seeking services at a homosexual-identified community-based agency in New York City. All subjects participated in an intensive HIV intervention program. Patterns of change in HIV sexual risk acts were based on assessments at four points (intake and 3, 6, and 12 months later) and were used to classify youths as demonstrating one of five patterns of anal and oral sexual acts: protected (anal: 45%, oral: 25%), improved (32% and 28%, respectively), relapse (5% and 8%), variable (8% and 15%), and unprotected (10% and 24%). Components of the health belief, self-efficacy, peer influence, coping, and distress models were assessed as predictors of these patterns. RESULTS: Protected and improved patterns of sexual risk acts were associated with low levels of anxiety, depression, and substance use and high self-esteem. CONCLUSIONS: These data suggest that HIV interventions must address non-HIV-related issues confronting youths in difficult life circumstances, particularly emotional distress and the role of peer networks for homosexual and bisexual youths.

Adaptation, Psychological↗
PubMed1994

Factors mediating changes in sexual HIV risk behaviors among gay and bisexual male adolescents.

OBJECTIVES: Factors mediating changes in sexual behaviors that increase the risk of human immunodeficiency virus (HIV) infection were monitored in a group of gay and bisexual male adolescents. METHODS: One hundred thirty-six males aged 14 to 19 years (Hispanic, 51%; African-American, 31%) were recruited from one gay-identified agency, were assessed at four points over a 1-year period, and participated in HIV preventive intervention sessions. RESULTS: Significant reductions occurred in the number of unprotected same-sex anal and oral acts. Those with less risk in their previous sexual history, those who did not engage in commercial sex, and those who attended more HIV intervention sessions were more likely to reduce their sexual risk. The impact of sessions varied significantly by race/ethnicity: African-American youths reduced their risk acts most dramatically. Abstinence was consistently and significantly more likely among younger youths and those who had been abstinent before enrollment. The youths significantly reduced the number of sexual partners following the intervention; this reduction in partners was maintained through the 12-month follow-up and was greatest among youths with no involvement in commercial sexual activity (prostitution). CONCLUSIONS: The efficacy of HIV prevention programs must be empirically evaluated.

Adolescent↗
PubMed1993

Single amino acid codon changes detected in louping ill virus antibody-resistant mutants with reduced neurovirulence.

Seven mutant viruses were derived from a Scottish strain of louping ill virus using a virus envelope-specific neutralizing monoclonal antibody. None of the mutants was neutralized and immunofluorescence microscopy confirmed that they did not bind to this antibody. Four mutants showed reduced mouse neurovirulence compared with parent virus and two mutants failed to induce protective immune responses in mice challenged with virulent tick-borne encephalitis virus. The mutants with the lowest virulence showed poor or undetectable haemagglutinating activity. The nucleotide sequence of the envelope glycoprotein gene of each of the seven mutants was determined and the deduced amino acid sequence was compared with parent virus. For each mutant, only a single amino acid codon change was detected and all the amino acid substitutions occurred within amino acid positions 308 to 311. A change from the amino acid aspartate to asparagine at amino acid position 308, which represented a potential glycosylation site, was the most effective substitution in reducing mouse neurovirulence. The results demonstrate the importance of critical sites within the envelope glycoprotein as determinants of virus virulence.

Animals↗
PubMed1992

Intradural bronchogenic cysts.

The pathological findings of an intradural and extramedullary cyst in the mid cervical spinal canal are described in a 55 year old woman who presented with a short history of pain and paraesthesia of the right arm. Intradural well defined solitary cystic lesions in the spinal canal are uncommon, their pathogenesis is poorly understood, and their nomenclature is confusing. In this case the cyst was a bronchogenic cyst; these are a rare form of such cysts and they are thought to be a malformation arising from a split notochordal syndrome and not a teratoma.

Bronchogenic Cyst↗
PubMed1992

Primary choroid plexus papilloma of the cerebellopontine angle: magnetic resonance imaging, computed tomographic and angiographic appearances.

The computed tomographic, angiographic and magnetic resonance imaging (MRI) appearances of a benign primary choroid plexus papilloma of the cerebellopontine angle are reported. Although benign, this tumour showed local invasion of the petrous temporal bone and mastoid air cells. The differential diagnosis of cerebellopontine angle lesions is discussed. Papilloma is suggested by the presence of a vascular, calcified, enhancing extra-axial mass in or around the cerebellopontine angle. MRI may show evidence of high vascularity and internal haemorrhage. Differentiation from other cerebellopontine tumours, most particularly meningioma, may not be possible on radiological features.

Adult↗
PubMed1992

Postoperative hyperfibrinogenemia in gastrointestinal surgery.

Fibrinogen titres were determined in two groups of patients undergoing major abdominal and thoracic surgical operations. Patients who underwent gastrointestinal surgical procedures had higher fibrinogen levels than those subjected to other appropriate thoracic surgical procedures. Fibrinogen titre elevation in patients with gastrointestinal abnormalities were significant on the 3rd, 5th and 7th days after surgery compared with the other group of patients. This higher response in fibrinogen could be attributable to the greater smooth muscle content in the gastrointestinal system than in the other tissues considered in this study. Smooth muscle tissue inflammation may lead to acute circulatory problems through postoperative increase in fibrinogen concentration.

Adolescent↗
PubMed1991

Descriptive epidemiology of primary central nervous system tumours in children: a population-based study.

This study was undertaken to investigate the incidence, outcome and referral patterns of central nervous system tumours in a defined childhood population over a recent 5-year period. The study incorporated pathological review of all available diagnostic material and follow-up assessed survival at a minimum of 5 years from diagnosis. One hundred and forty-seven cases were reviewed, representing an annual incidence of 26.5 per million children aged less than 15 years. The distribution of individual diagnoses by age, sex and anatomical site was similar to comparable data collected previously in the United Kingdom and North America, but the inclusion of 28 cases (19%) without biopsy suggested that the wider use of computed tomography might account for a small increase in incidence over previous estimates. Analysis of referral to the Regional Paediatric Oncology Unit showed that the patients referred were younger than those not referred and were over-represented amongst the diagnoses of medulloblastoma, ependymoma and brain stem glioma, which carry the worst prognosis. Survival for all diagnoses together was 51% at 5 years, ranging from 13% for unbiopsied brain stem gliomas to 100% for juvenile astrocytomas. Referral to the Regional Unit appeared to have some survival advantage for children with medulloblastoma, although this was not statistically significant. Accurately reviewed data such as these are essential in order to assess current workload and treatment success, in addition to enabling investigation of future diagnostic and treatment strategies.

Adolescent↗
PubMed1991

The effect of external pituitary irradiation on elevated serum prolactin levels in patients with pituitary macroadenomas.

The response of serum prolactin to external radiotherapy was studied in 58 patients (32 women) with pituitary tumours, aged between 16 and 75 years. Forty-four patients underwent pituitary surgery before radiotherapy. Six patients were irradiated with a regimen of 20 Gy in eight fractions over 10-11 days and the remainder received 35-42.5 Gy in 15 fractions over 20-22 days. Following radiotherapy, 44 patients received additional treatment with dopaminergic agonists. Prolactin levels ranged from 1078 to 491,000 mU/l (median 11,750 mU/l) before radiotherapy and all but three patients showed a fall in serum prolactin (measured 4 weeks after stopping bromocriptine in those on dopamine agonist therapy) during observation over periods of up to 154 months. All patients had evidence of pituitary fossa erosion or expansion at presentation and large tumours (Hardy-Vezina Grade 3-4) were more common in male patients (chi 2 = 10.08, p less than 0.01). The rate of fall of serum prolactin levels was greater in patients with true prolactin-secreting tumours when compared with those who had stalk or hypothalamic damage (p less than 0.005). The rate of decline of serum prolactin was also significantly related to the pre-radiotherapy value (rho = 0.519, p less than 0.01). A serum prolactin level less than 500 mU/l was achieved in 31 out of 44 patients treated with radiotherapy and dopaminergic agonist but only nine remained normoprolactinaemic when medication was discontinued for 4 weeks or more. The serum prolactin level fell permanently to less than 500 mU/l in two of 14 patients treated with radiotherapy only. Actuarial analysis of data from all patients indicated a 50 per cent probability that prolactin would be reduced to less than 500 mU/l by 10 years; this increased to 58 per cent for patients with smaller tumours (Hardy-Vezina grade 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1989

Immunoblotting analysis of the reaction of wildebeest, sheep and cattle sera with the structural antigens of alcelaphine herpesvirus-1 (malignant catarrhal fever virus).

Malignant catarrhal fever (MCF) is a disease of cattle and some other ruminants caused by alcelaphine herpesvirus-1 (AHV-1), a virus of wildebeest. The disease also occurs in the absence of wildebeest and is then thought to be caused by a viral agent harboured by the sheep. The structural proteins of AHV-1 have been used as antigens for the immunoblotting analysis of sera from wildebeest, sheep and cattle infected by either AHV-1 or the "sheep-associated" form of the disease. Wildebeest sera showed a uniform response reacting strongly with six polypeptides. Sheep sera also gave positive results but individual sera reacted with varying subsets of the antigens recognized by wildebeest. These results support the earlier suggestion that sheep harbour a herpesvirus related to AHV-1. A bovine serum from a case of MCF caused by AHV-1 also reacted only with a subset of the six wildebeest-reactive polypeptides. Sera from cattle affected with the "sheep-associated" form of the disease gave reactions in only two of the eight cases tested; both positive sera reacted to a few polypeptides only.

Animals↗
PubMed1987

Adrenal cortical tumours: epidemiological and familial aspects.

Epidemiological data on the 14 cases of adrenal cortical tumour registered with the Manchester Children's Tumour Registry from 1954 and 1985 are presented. The incidence of adrenal cortical carcinomas was 0.3%, mainly in girls, most of whom presented with virilisation. The incidence of neoplastic disease among close relatives was ascertained, but, except in siblings, this was not significantly higher than would be expected. Evidence from extended pedigrees, however, indicates that at least four of the children could be members of families with the SBLA (sarcoma, breast and brain tumour, leukaemia, laryngeal and lung cancer, and adrenal cortical carcinoma) cancer family syndrome, and that other relatives may be at risk of developing such neoplasms.

Adolescent↗
PubMed1986

Inhibitory effect of anoxia on 125I-insulin binding by rat hepatocytes.

We have examined the possibility that 125I-insulin binding by isolated rat hepatocytes is modulated by cellular ATP levels. To avoid complications due to ATP-dependent internalization of bound insulin, 125I-insulin binding was determined at 10 degrees C; at this temperature, equilibrium binding was achieved after incubation for 4-6 h. When hepatocytes were incubated at 37 degrees C under anaerobic conditions, ATP levels and 125I-insulin binding were both lowered by about 65%. Anoxia inhibited the association of 125I-insulin with the hepatocyte receptor; the dissociation of insulin from hepatocytes was not affected. Cellular ATP levels and 125I-insulin binding were both restored when anaerobic cells were incubated further at 37 degrees C under aerobic conditions. When anaerobic cells were incubated in air at 10 degrees C during the insulin binding assay, 125I-insulin binding recovered completely, but ATP levels were unaffected. The inhibitory effect of anoxia on 125I-insulin binding was not due to any effect on 125I-insulin degradation or on cell viability. We conclude (1) that the ability of hepatocytes to bind insulin can be modulated on a short-term basis in response to the metabolic status of the cell, and (2) that modulation of the liver cell insulin receptor is not a function of cellular ATP levels.

Anaerobiosis↗