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Biomedical subjects

A O'Brien

Publications and source records attributed to A O'Brien.

At least 55 records · Page 3Linked to original sources
PubMed1996

[Effects of hormone replacement therapy in bone resorption, in post-menopausal women].

BACKGROUND: The effects of different therapies on bone loss rate can be measured using biochemical markers of bone resorption such as urinary hydroxyproline. AIM: To study the effects of hormone replacement therapy on urinary hydroxyproline in postmenopausal women. PATIENTS AND METHODS: Eighty three postmenopausal women without hormone replacement therapy, 54 postmenopausal women receiving hormone replacement therapy and 16 premenopausal women (considered as the control group) were studied. Hydroxyproline was measured in an early morning urine sample, after one day of diet without meat or gelatin. RESULTS: Urinary hydroxyproline in premenopausal women was 33.7 +/- 7.9 mg/g creatinine. The figure for postmenopausal women with hormonal replacement therapy was 33.7 +/- 5.9 mg/g creatinine. Postmenopausal women without replacement therapy had an urinary hydroxyproline of 47.4 +/- 8.5 mg/g creatinine, significantly higher than that of premenopausal and supplemented women. In 21 postmenopausal women, hydroxyproline was measured before and after three months of replacement therapy, values decreased 35.5 +/- 11% in this period and there was a direct correlation between initial values and the degree of reduction (r = 0.69, p < 0.001). CONCLUSIONS: Postmenopausal women receiving hormone replacement therapy have a urinary hydroxyproline excretion similar to that of premenopausal women.

Adult↗
PubMed1995

Experience with abdominal wall closure for patients with congenital diaphragmatic hernia repaired on ECMO.

Congenital diaphragmatic hernia (CDH) and its attendant lack of abdominal domain can create major technical challenges with respect to diaphragmatic and abdominal wall reconstruction, especially in seriously ill infants who require extracorporeal membrane oxygenation (ECMO). The authors reviewed the medical records of all infants with CDH repaired on ECMO at their institution (group 1, 15 patients), and compared them with infants having CDH repair before ECMO (group 2, 20 patients) and with those who had CDH repair but did not require ECMO (group 3, 15 patients). Thirty-seven of 50 patients survived (74%): 10 in group 1, 12 in group 2, and all 15 in group 3. There was a statistically significant difference (P < .001) with respect to the requirement of a polytetrafluoroethylene (PTFE) diaphragmatic patch for patients in group 1 versus those in both groups 2 and 3. There was also a significant difference in the number of patients in whom the abdomen could not be closed (P < .001 for group 1 v groups 2 and 3). Infants who require ECMO before CDH repair are more likely to have large diaphragmatic defects that require prosthetic reconstruction, and abdominal wall closure problems resulting from loss of abdominal domain, which further complicate the management of the physiological derangements from pulmonary hypoplasia and persistent pulmonary hypertension.

Abdominal Muscles↗
PubMed1995

Measuring graduate attitudes to educational preparation for practice in mental health nursing.

Concern has been expressed in recent nursing research literature and within the nursing profession about the durability and quality of psychiatric/mental health nurse education curricula. The transition from hospital-based to university-based nursing education, provided the impetus for a study that addressed problems related to the development and implementation of theoretical, clinical and educational practice experiences for students of mental health nursing. This paper describes the results of an instrument developed to measure educational satisfaction as preparation for clinical practice on the following four subscales: clinical practice; knowledge and skills; mental health nursing; teaching and learning. Significant differences were detected on the foregoing scales for younger registered nurses, for nurses registered for less than 5 years, and for registered nurses in different employment capacities. This study draws attention to the Australian need to evaluate the effectiveness of current educational preparation for mental health nursing and the methodological difficulties in such an evaluation.

Adult↗
PubMed1993

The pharmacology of LY290324 in the guinea-pig: an orally active, potent and selective cysteinyl leukotriene receptor antagonist.

This study describes the evaluation of LY290324 as a leukotriene D4 (LTD4) receptor antagonist in guinea-pigs. In vitro, LY290324 was a potent and persistent antagonist of the contractile responses to LTD4 and LTE4 with pA2 values of 9.1 +/- 0.2 and 8.9 +/- 0.17 respectively. The antagonism appeared competitive and selective for LTD4/E4, as LY290324 (10(-6) M) had no effects on contraction elicited by LTC4, prostaglandin F2 alpha (PGF2 alpha), histamine and acetylcholine. In vivo the compound was highly effective in a dose-dependent manner by the intravenous, oral and inhaled routes in preventing LTD4-induced bronchospasm. Administered i.v. LY290324 prevented the development (ED50 = 3.4 micrograms/kg) of an LTD4-induced bronchospasm and readily reversed an established bronchospasm, but failed to prevent the bronchospasm to either histamine or platelet activating factor (PAF). Oral studies demonstrated efficacy for at least 12 h. Administered orally 6 h previously, LY290324 reduced LTC4, LTD4 and LTE4-induced bronchospasm with ED50s of 0.3, 0.28 and 0.37 mg/kg respectively. Relatively low inhaled levels (2 micrograms/kg) also significantly reduced (72.5%, P < 0.001) LTD4-induced bronchospasm. Finally the compound administered orally was effective in reducing antigen-induced bronchospasm in immunologically sensitised animals.

Administration, Inhalation↗
PubMed1992

A major solid undifferentiated carcinoma pattern correlates with tumour progression in locally advanced prostatic carcinoma.

Solid undifferentiated carcinoma was the major microscopic pattern in 24 prostatic carcinomas, 12 of which were clinically recurrent. Tumour cells were uniform, with moderately hyperchromatic nuclei and indistinct cytoplasm, and were arranged in solid or focally irregular aggregates. In areas, the tumour cells were large with vesicular nuclei, nucleoli and more abundant cytoplasm. In previous specimens, solid undifferentiated carcinoma was absent or was a minor pattern. Twenty of 23 cases showed prostate specific antigen and prostatic acid phosphatase immunoreactivity, and nine of 17 cases contained scattered argyrophilic or chromogranin-immunoreactive cells. On proliferating cell nuclear antigen immunostaining of 12 specimens, the mean tumour proliferative fraction in solid undifferentiated carcinoma (range: 10.5-18%) was greater than in areas of grade 3 prostatic carcinoma (range: 3-6%). In all 22 stage C and D cases, there was a close correlation with clinical evidence of tumour progression, and the overall 2-year survival rate was only 16.7%. It is concluded that a major solid undifferentiated pattern correlates with increased biological aggressiveness and a poor prognosis in locally advanced prostatic carcinoma.

Carcinoma↗
PubMed1992

Effects of a simulated microgravity model on cell structure and function in rat testis and epididymis.

A tail-suspension (TS) rat model used to simulate microgravity was tested for its effects on the anatomy, cell structure, and function of the testis and epididymis in sexually mature male rats. Rats suspended for 7 days without inguinal canal ligation exhibited a significant (P less than or equal to 0.05) reduction in testis weight compared with controls (1.55 +/- 0.04 to 1.1 +/- 0.02 g). Except for the liver, epididymis, and adrenals of TS rats and TS rats allowed to recover for 7 days, no significant (P less than or equal to 0.05) change was observed in the weight of other body and accessory sex organs. A histological examination of the testes and epididymides of model animals revealed disorganized seminiferous tubules and accumulation of large multinucleated cells and spermatids in the lumen of the epididymis. A significant (P less than or equal to 0.05) increase in serum luteinizing hormone (53.1 +/- 6.7 to 66.2 +/- 10.1 ng/ml) and follicle-stimulating hormone (257 +/- 25 to 305 +/- 38 ng/ml) was observed in TS nonligated rats, whereas serum prolactin and testosterone levels were observed to decline from 8.3 +/- 1.3 to 5.1 +/- 0.29 and 7.1 +/- 1.3 to 3.8 +/- 0.25 ng/ml, respectively. Decreases in testis protein content and testosterone levels of the testis, interstitial fluid, and epididymis were also observed in model animals. These data demonstrate that the suspension procedure used in the National Aeronautics and Space Administration TS model results in the testis and epididymis translocating into the abdominal cavity, causing cellular degeneration and organ dysfunction.

Animals↗
PubMed1991

A critical analysis of the use of sialic acid determination in the diagnosis of malignancy.

The measurement of serum sialic acid in sera from individuals with leukemia, breast, gastrointestinal, lung and bladder cancers, brucellosis and manic depression is described. The serum sialic acid levels were also examined in mice bearing Landschutz ascites tumours. The presence of sialic acid-enriched glycopeptides in serum was shown. The results indicate that while sialic acid may be significantly elevated in sera of some tumour-bearing individuals, it is not solely tumour-derived. Its application as a tumour marker is limited and requires critical analysis.

Animals↗
PubMed1991

The basolateral amygdala-ventral striatal system and conditioned place preference: further evidence of limbic-striatal interactions underlying reward-related processes.

The effects on the expression of a conditioned place preference of bilateral, excitotoxic amino acid-induced lesions of the basolateral region of the amygdala, or the ventral striatum, or asymmetric, unilateral lesions of both structures were studied. The place preference was conditioned by exposing hungry rats to sucrose in a distinctive environment. Following acquisition, bilateral quisqualate-induced lesions of the basolateral amygdala, as well as bilateral quinolinate-induced lesions of the ventral striatum, abolished the conditioned place preference. Bilateral ventromedial, but not dorsolateral, quinolinate-induced caudate-putamen lesions attenuated the place preference. Combining a unilateral lesion of the basolateral amygdala with a contralateral lesion of the ventral striatum also disrupted the conditioned place preference. These data provide further support for the hypothesis that the basolateral amygdala and ventral striatum are important parts of a neural system subserving stimulus-reward associations.

Amygdala↗
PubMed1991

The relationship between development of lung inflammation and changes in bone marrow populations in guinea-pigs following inhaled antigen challenge.

Sensitised guinea-pigs were exposed to aerosolised antigen. The resultant cellular infiltration into the lung was assessed in lung tissue and bronchoalveolar lavage fluid 6, 24, 72 h and 7 days later. An early neutrophil infiltration peaking at 6 h was succeeded by eosinophil migration which persisted for 7 days, at which time some of the eosinophils appeared immature. The lung eosinophilia was accompanied by an initial fall in eosinophilic cells in the bone marrow, followed by an increase in this population. Treatment with dexamethasone (25 mg/kg i.p.) given daily for 7 days after antigen challenge reduced the lung eosinophilia and observed bone marrow changes.

Administration, Inhalation↗
PubMed1991

Proliferation of normal and malignant human epithelial cells post irradiation.

Fragments of human oesophageal mucosa, urothelium, squamous and adenocarcinoma of the oesophagus and carcinoma of the bladder have been plated in culture and irradiated. The cells growing from the explanted tissues have then been studied for four weeks post irradiation to assess the overall rate of growth from the irradiated explants and the fraction of proliferating cells. The results show that when using cell number as an endpoint it is possible to derive growth curves from this type of data which permit a doubling time to be obtained for the cell population surviving different doses. In an attempt to determine the proliferating fraction of the cell population, cultures were labelled at appropriate intervals with tritiated thymidine and were also stained with Ki-67 antiproliferating antigen. The results show an interesting relationship between the dose response obtained for cell labelling with tritiated thymidine and area of cellular outgrowth. Ki-67 staining when used carefully and analysed as described was a useful indicator of proliferating cells. The results provide a means of determining the post irradiation growth potential of fragments of tissue from human organs and may be important for determined overall response of the tumour bulk to proposed treatment.

Autoradiography↗