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Biomedical subjects

T O'Connor

Publications and source records attributed to T O'Connor.

At least 73 records · Page 4Linked to original sources
PubMed1998

Prostanoid signaling, localization, and expression of IP receptors in rat thick ascending limb cells.

It is widely held that only one prostacyclin (IP) receptor exists that can couple to guanine stimulatory nucleotide binding proteins (Gs) leading to activation of adenyl cyclase. Although IP receptor mRNA is expressed in vascular arterial smooth muscle cells and platelets, with lower level expression in mature thymocytes, splenic lymphocytes, and megakaryocytes, there is no molecular evidence for IP receptor expression in renal epithelial cells. The purpose of the present study was to obtain molecular evidence for the expression and localization of the IP receptor and to study the signaling pathways of IP receptor in rat medullary thick ascending limb (MTAL). Biochemical studies showed that IP prostanoids do not increase cAMP in rat MTAL. However, in the presence of vasopressin, inhibition of cAMP formation by prostacyclin (PGI2) analogs is pertussis toxin sensitive and does not activate protein kinase C. In situ hybridization studies localized IP receptor mRNA expression to MTAL in the rat kidney outer medulla. The results of RT-PCR of freshly isolated RNA from MTAL, with primers specific for the mouse IP receptor cDNA, produced an amplification product of the correct predicted size that contained an expected Nco I endonuclease restriction site. We conclude that rat renal epithelial cells express the IP receptor, coupled to inhibition of cAMP production.

Adenylate Cyclase Toxin↗
PubMed1998

Realising a nursing dream.

Establishing a community nursing service for Pacific Island families in Christchurch has not been without problems. But the project has been an undoubted success.

Community Health Nursing↗
PubMed1998

Partners in the community.

TO MARK this year's International Nurses' Day and the theme chosen by the International Council of Nurses (ICN)--Partnership for Community Health--Kai Tiaki Nursing New Zealand profiles ten nurses who work hand-in-hand with their communities. Our search for suitable people took us from Auckland to Queenstown, from small rural settings to large metropolitan areas. Our final selection presents two Plunket nurses, a district nurse, a diabetes nurse specialist, a community midwife, an oncology nurse specialist, a caregiver, a practice nurse, a mental health nurse and a rural emergency nurse practitioner.

Community Health Nursing↗
PubMed1998

Nurses' role in Maori health.

Maori nurses have a pivotal role to play in improving Maori health and the Health Funding Authority wants to make sure they're in a position to do so.

Health Policy↗
PubMed1998

Preparing students for a nursing career.

Undergraduate education of nursing students has often been the target of criticism. One polytechnic nursing tutor shares the challenges of her working life.

Education, Nursing, Baccalaureate↗
PubMed1998

Protecting members and promoting safety.

NZNO has been involved in some major investigations into public health services over the last three years. There have been many lessons for the organisation and its members.

Expert Testimony↗
PubMed1997

The dependence of radioimmunoassay detection limits on antibody affinity.

Competitive radioimmunoassay standard curves for progesterone were established with tritiated progesterone and six different anti-progesterone monoclonal antibodies ranging in affinity from 1.23 x 10(8) to 2.82 x 10(10) l/mol. The detection limits for these curves ranged from 133 to 6,670 pmol/l final assay concentration (16.7 to 839.1 pg/tube). Separately, a mass-action mathematical model was used to predict lower detection limits for assays run under equivalent conditions with the six antibodies. When compared to the experimental data the predictions were reliable for the higher affinity antibodies but became less accurate as the affinity decreased.

Animals↗
PubMed1997

Activation of the K-ras oncogene in colorectal neoplasms is associated with decreased apoptosis.

BACKGROUND: Recent in vitro data indicate that the oncogenic effects of activated ras genes may be mediated, at least in part, through inhibition of apoptotic cell death. To examine this proposition in vivo, the relationship between mutations of the K-ras gene and the frequency of apoptosis was studied in a series of 69 sporadic colorectal neoplasms (11 adenomas and 58 carcinomas). METHODS: Mutations in codon 12 of K-ras were determined by a single tube, enriched polymerase chain reaction. Apoptotic cells in tumor sections were identified by in situ end-labeling of fragmented DNA, whereas levels of bcl-2 and p53 proteins were determined by immunohistochemistry. RESULTS: Tumors with mutant K-ras had a significantly lower apoptotic index than those with the wild-type allele (P < 0.05). They were also more likely to exhibit positive bcl-2 staining (P < 0.05). Adenomas showed significantly greater bcl-2 positivity than carcinomas (89% and 51%, respectively; P < 0.05). The frequency of apoptosis in these tumors was not related to either bcl-2 positivity or p53 status. CONCLUSIONS: These findings suggest that activation of K-ras in colorectal carcinoma may inhibit apoptosis and thus favor tumor progression. Alternatively, this association may reflect an accumulation of K-ras mutations in cells in which normal apoptotic pathways have been impaired.

Adenoma↗
PubMed1997

Pathological and genetic correlates of apoptosis in the progression of colorectal neoplasia.

PURPOSE: Apoptosis is commonly observed in a variety of human tumors, and some of the genetic events which control this process have been identified in vitro. The aim of this study was to determine the frequency of apoptosis in colorectal neoplasms and to examine its relationship to a number of pathological parameters, to the presence of mutations in the p53 tumor suppressor gene, and to overexpression of the bcl-2 oncoprotein. METHODS: A total of 109 colorectal neoplasms (26 adenomas 83 carcinomas) were examined. An in situ end-labelling assay was used to detect apoptosis in paraffin-embedded tumor sections, and scores were determined by light microscopy. The p53 and bcl-2 status were determined by immunohistochemistry. RESULTS: Apoptotic frequency increased with tumor progression. Normal mucosa contained significantly fewer apoptotic cells than adenomas or carcinomas. Similarly adenomas showed less apoptosis than carcinomas, and the frequency of apoptosis increased with Dukes' stage. Overall, changes in apoptotic frequency were inversely related to the level of bcl-2 expression, but were not related to the p53 status of the tumors. CONCLUSIONS: The frequency of apoptosis in colorectal neoplasia appears to increase in the course of tumor progression in association with a decline in bcl-2 expression, but is not influenced by p53 gene mutations.

Adenocarcinoma↗