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Biomedical subjects

D O'Brien

Publications and source records attributed to D O'Brien.

At least 55 records · Page 3Linked to original sources
PubMed1994

Central sympathetic control of spinal endothelin release in the rat.

Endothelin and its receptors have been identified in the spinal cord. Intrathecal administration of endothelin-3 produces hypotension in anesthetized rats. The present study was designed to identify whether endothelin-3 is released upon changes in sympathetic nervous activity. Endothelin-3-like immunoreactivity in spinal superfusates was directly correlated with resting arterial pressure. Endothelin-3 levels were enhanced by hypothalamic stimulation and by hemorrhage-induced hypotension and reduced by nitroprusside-induced hypotension. These findings suggest that sympathetic activation enhances endothelin-3 release but that nitroprusside may act directly to suppress release. We propose that endothelin-3 plays a role in spinal regulation of sympathetic outflow.

Anesthesia↗
PubMed1994

Evaluation of cold-adapted, reassortant influenza B virus vaccines in elderly and chronically ill adults.

The safety and immunogenicity of two recent cold-adapted reassortant influenza B viruses were evaluated in persons at high risk for influenza-related morbidity and mortality. Ambulatory adults > 65 years old or with chronic high-risk conditions were randomly assigned to receive parenteral trivalent inactivated influenza vaccine containing either influenza B/Ann Arbor/86 or B/Yamagata/88 hemagglutinin antigens, cold-adapted reassortant influenza B/Ann Arbor/1/86 or B/Yamagata/16/88 viruses (10(7.2) TCID50), or placebo in double-blind fashion. Cold-adapted vaccine viruses were well tolerated, with similar rates of respiratory symptoms in all groups. There were no changes in spirometry or oxygen saturation following vaccination. Immune responses to both types of vaccine were modest, with serum antibody responses occurring significantly more frequently and with higher magnitude in those receiving inactivated than in those receiving cold-adapted vaccine. Cold-adapted, reassortant influenza B vaccines are safe in the elderly and those with chronic illness but are not optimally immunogenic in this group.

Aged↗
PubMed1994

Detection of Aeromonas salmonicida, causal agent of furunculosis in salmonid fish, from the tank effluent of hatchery-reared Atlantic salmon smolts.

The fish pathogen, Aeromonas salmonicida, could be detected only by bacteriological culture from the kidney of dead or moribund fish in one tank in a hatchery rearing Atlantic salmon (Salmo salar L.) smolts. However, by using a DNA probe specific for this species, allied to a PCR assay, the pathogen could be detected in water, feces and effluent samples taken from this fish tank. Also, the presence of the pathogen was found in effluent samples from two fish tanks containing apparently healthy fish. Subsequently, the presence of pathogen in these tanks was confirmed by an increase in the daily mortality rate and by a plate culture from moribund fish.

Aeromonas↗
PubMed1994

Factor VIIa and other haemostatic variables following bone marrow transplantation.

Hepatic venocclusive disease causes considerable morbidity and mortality following bone marrow transplantation. There are two hypotheses regarding the aetiology of this syndrome; firstly that changes in plasma coagulation factors and natural anticoagulants lead to a prothrombotic state and secondly that endothelial cell activation stimulates intravascular deposition of fibrin. We have investigated these mechanisms by measuring the changes in proteins C and S and factors VII and X in the post transplant period and by using the plasma concentration of factor VIIa as an in vivo marker of potential endothelial cell tissue factor expression. Protein C fell in both allograft and autograft patients but more so in the allografts. Similar results were found for factors VII and X. These changes were predominantly due to hepatic dysfunction induced by the chemo-radiotherapy. Factor VIIa levels were unchanged in both the allograft and autograft patients. We conclude that there is no convincing evidence for a procoagulant state following BMT as there are both anticoagulant and procoagulant changes. The absence of any changes in factor VIIa levels suggests that tissue factor was not exposed to the general circulation following BMT but does not exclude focal expression at the sites of thrombosis.

Bone Marrow Transplantation↗
PubMed1994

Replication of a managed health care initiative for people with mental retardation living in the community.

To improve understanding of the cost-effectiveness of a managed health care program for individuals with mental retardation, we have described financing, utilization, and outcomes of the Developmental Disabilities Center at Morristown Memorial Hospital. The costs and benefits of health care coordination, a key feature of this program, were discussed. Under this model, annual, unreimbursed costs of health care coordination in 1989 averaged $668 for people with severe mental retardation. However, the total reimbursable costs of inpatient care were reduced. In addition, medical outcome data from ongoing research projects suggest that the program has been an important vehicle for improving the health of people with mental retardation in the community. The costs, revenues, and financing of this program were presented in order to assist candidate sites in the replication of this model. The role of this type of program in health care reform was discussed.

Community Mental Health Services↗
PubMed1994

Occipital condylar dysplasia in two Jacob sheep.

Two young Jacob sheep which presented with severe ataxia and torticollis had abnormally formed atlanto-occipital joints. Postmortem examination revealed marked dissimilarity in size between the left and right occipital condyles, with reduction in size of the foramen magnum. The atlantoaxial joint and dens were normally formed, and were not abnormally positioned in radiographs taken of one lamb. Histological evaluation of the cervicomedullary junction demonstrated extensive loss of axons and myelin, gliosis, and mild hydromyelia in one lamb.

Animals↗
PubMed1993

A Null mutation in the vasopressin V2 receptor gene (AVPR2) associated with nephrogenic diabetes insipidus in the Hopewell kindred.

Congenital nephrogenic diabetes insipidus (DIR) is a rare X-linked hereditary disorder in which the renal collecting duct is unresponsive to arginine vasopressin; thus, the urine is consistently hypotonic to plasma. Recently, the association between the V2 receptor gene (AVPR2) and DIR has been proven. We have determined the gene sequence of four family members, from three generations, of a large North American family with CNDI who were originally part of the study used to formulate the Hopewell hypothesis. It had been proposed that a single DIR gene defect was introduced to North America by a member of an Ulster Scot kindred arriving on the ship Hopewell in 1761. DNA sequencing of the AVPR2 has identified a single base transversion from G-->A which changes tryptophan 71 to a stop codon in affected patients. This point mutation causes a truncation of the receptor leading to an essentially null allele. These data and other recently described mutations in the AVPR2 in North American pedigrees, descended from Ulster Scot ancestors and other origins, make the assertion of a founder effect proposed in the Hopewell hypothesis invalid.

Amino Acid Sequence↗
PubMed1993

Epstein-Barr virus in normal, pre-malignant, and malignant lesions of the uterine cervix.

AIM--To detect the presence or absence of Epstein-Barr virus (EBV) in cervical lesions ranging from normality to invasive malignancy. METHODS--Eighteen randomly selected cases of invasive squamous cell carcinomas of the uterine cervix were examined as well as 25 cases each of normal cervices and those showing cervical intra-epithelial neoplasia (CIN) I, II, and III. DNA-DNA in situ hybridisation, using a biotinylated probe to the Bam H1 "W" fragment of EBV, was carried out in addition to the polymerase chain reaction using specific primer sequences that flank a 153 base pair segment of the Bam H1 "W" region of the EBV genome and which do not cross-amplify other DNA herpes viruses. Positive control material included paraffin wax embedded P3 HR1 lymphoblastoid cells (containing high copy numbers of EBV) and two nasopharyngeal carcinomas positive for EBV. RESULTS--Neither normal nor CIN I tissue was positive. Eight per cent of CIN II tissue was positive; 8% of CIN III, and 43% of carcinomas were positive for EBV. CONCLUSION--The study shows that the virus is present in some cases of cervical carcinoma and to a lesser degree in some premalignant lesions of the cervix, but the exact association between it and cervical oncogenesis, be it causative or incidental, remains to be determined.

Base Sequence↗
PubMed1992

Protective efficacy of combined live intranasal and inactivated influenza A virus vaccines in the elderly.

OBJECTIVE: To evaluate the efficacy of adding intranasal live attenuated cold-adapted influenza A vaccine to inactivated influenza vaccine to prevent influenza A in elderly residents of long-term-care institutions. DESIGN: Randomized, double-blind, placebo-controlled study conducted over 3 years. SETTING: Three large nursing homes. PARTICIPANTS: A total of 523 residents of nursing homes (mean age, 84.2 years). INTERVENTIONS: All participants received trivalent inactivated influenza vaccine parenterally and were randomly assigned to receive either live attenuated influenza A (H3N2) virus vaccine or placebo intranasally. MEASUREMENTS: Laboratory-documented influenza A was defined as a respiratory illness plus isolation of influenza A virus from nasal secretions, significant serologic response, or both. Participants were considered to have been exposed to influenza A if they resided in an institution in which cases of influenza A were documented. Outbreak-associated illnesses were defined as those occurring between the first and last isolation of influenza virus from within the institution, +/- 3 days. RESULTS: Participants who received intranasal vaccine and were subsequently exposed to influenza A had significantly lower rates of laboratory-documented influenza A (9 of 162 vaccine recipients compared with 24 of 169 placebo recipients; vaccine protective efficacy, 60.6%; 95% CI, 18% to 82%), outbreak-associated respiratory illnesses (13 of 162 vaccine recipients compared with 34 of 169 placebo recipients; vaccine protective efficacy, 56.8%; CI 23% to 76%), and outbreak-associated influenza-like illnesses (6 of 162 vaccine recipients compared with 18 of 169 placebo recipients; vaccine protective efficacy, 65.0%; CI 17% to 86%). CONCLUSIONS: Intranasal immunization with live attenuated influenza A virus vaccine provided additional protection against influenza A when added to parenteral trivalent inactivated influenza vaccine among elderly nursing home residents.

Administration, Intranasal↗
PubMed1992

Silica exposure in hand grinding steel castings.

Exposure to silica dust was studied in the grinding of castings in a steel foundry that used conventional personal sampling methods and new real-time sampling techniques developed for the identification of high-exposure tasks and tools. Approximately one-third of the personal samples exceeded the National Institute for Occupational Safety and Health recommended exposure limit for crystalline silica, a fraction similar to that identified in other studies of casting cleaning. Of five tools used to clean the castings, the tools with the largest wheels, a 6-in. grinder and a 4-in. cutoff wheel, were shown to be the major sources of dust exposure. Existing dust control consisted of the use of downdraft grinding benches. The size of the casting precluded working at a distance close enough to the grates of the downdraft benches for efficient capture of the grinding dust. In addition, measurements of air recirculated from the downdraft benches indicated that less than one-half of the respirable particles were removed from the contaminated airstream. Previous studies have shown that silica exposures in the cleaning of castings can be reduced or eliminated through the use of mold coatings, which minimize sand burn-in on the casting surface; by application of high-velocity, low-volume exhaust hoods; and by the use of a nonsilica molding aggregate such as olivine. This study concluded that all these methods would be appropriate control options.

Air Pollutants, Occupational↗
PubMed1992

General practice estimates of the prevalence of common chronic conditions.

This study measured the prevalence of chronic medical conditions in 4,549 middle aged persons attending three large general practices in Dublin over the course of a calender year. The prevalence of the following conditions were measured: coronary heart disease, hypertension, stroke, diabetes, asthma, chronic bronchitis, rheumatic disorders, dyspepsia, depression, anxiety disorders, psychoses, and cancer. In order to obtain a valid denominator for the study a second community based study was carried out in the same areas to determine what proportion of persons visit their general practitioner over the course of a year. Overall 40.5% of males and 44% of females suffered from a least one of the twelve conditions, with rheumatic disorders having the highest prevalence (14.5%) and psychotic disorders the lowest (0.75%).

Adult↗
PubMed1992

An explanation for the difference in general practitioner consultation rates between GMS and non-GMS patients.

This study compares annual consultation rates between 3,111 General Medical Services and private patients, and their family doctors in three large general practices in Dublin. Visiting rates were substantially different between practices and between GMS and private patients. However, GMS patients were older and had 50% more chronic illnesses. When the effects of age and illness were controlled in a multiple regression model, GMS status accounted for less than 5% of the variation in visiting rates. GMS patients consult their practitioners in proportion to their medical need.

Adult↗
PubMed1991

Fibrinolytic activity in patients with idiopathic and secondary deep venous thrombosis.

Decreased fibrinolytic activity (FA) is considered a risk factor in the development of deep venous thrombosis (DVT). The purpose of this study was to test the hypothesis that an abnormally low FA is more likely in idiopathic DVT as opposed to DVT in the presence of other predisposing risk factors. 156 patients were studied three months after an acute DVT confirmed by venography. In 82 patients a predisposing factor such as trauma, surgery or malignancy was present. In 74, DVT was idiopathic. Fibrinolytic activity was measured in all patients using the following tests: 1. Euglobulin Lysis Time (ELT, in minutes). 2. Global Fibrinolytic activity (FA in mg fibrin lysed per hour). ELT measures plasminogen activator activity (PAA) while FA which is a more global test measures the net effect of the PAA, the plasminogen activator inhibitor (PAI) and the clot structure. PAI was measured in 67 patients from both groups using an Enzyme-Linked immunosorbent assay (ELISA). The results obtained show a significant increase in the incidence of abnormal FA and ELT in the idiopathic group. This supports the hypothesis that low FA is an aetiological factor in the development of idiopathic DVT. The results also demonstrate the importance of associating the FA test to the classical tests such as ELT, PA and PAI for the detection of hypofibrinolysis.

Fibrinolysis↗