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Biomedical subjects

K Quinn

Publications and source records attributed to K Quinn.

At least 19 recordsLinked to original sources
PubMed1998

A method for direct patch-clamp recording from smooth muscle cells embedded in functional brain microvessels.

The aim of this project was to develop a method to enable routine application of all patch-clamp configurations to smooth muscle cells while they remain embedded in blood vessels. Small blood vessels were isolated from rabbit brain using an enzymatic and mechanical procedure. Vessels were identified under a microscope and the majority were small arterioles with a mean external diameter, in Ca2+-containing (1.5 mM) solution, of 29 microm and variable lengths of 100 microm or more. Arterioles excluded trypan blue, constricted in response to 60 mM K+ and dilated in response to levcromakalim. Patch-clamp gigaOhm seals were made regularly on smooth muscle cells embedded in arterioles. The membrane potential recorded using amphotericin-B-containing patch pipettes averaged -72 mV. Short arteriolar segments could be voltage-clamped. Injection of depolarising current or bath application of 10 mM Ba2+ induced constriction of the entire arteriolar segment. Cell-attached patch, inside-out patch and outside-out patch recordings were made readily and K+ channel unitary currents were studied. The method is readily applied and has several advantages over previous methods for the study of ion channels in smooth muscle cells. Notably, avoidance of single-cell isolation means that enzymatic treatment is minimised and cells can be studied within their normal environment of the blood vessel wall.

Animals↗
PubMed1998

K(+)-induced dilation of a small renal artery: no role for inward rectifier K+ channels.

OBJECTIVE: To investigate the mechanism of K(+)-induced vasodilation in a small artery from the kidney, with a particular emphasis on the role of inward rectifier K+ channels. METHODS: Lumen diameter and isometric tension recordings have been made from rabbit renal arcuate artery using pressurised- and wire-myography respectively. In addition, conventional whole-cell and amphotericin-perforated patch whole-cell recordings have been made from single smooth muscle cells isolated from the vessel. RESULTS: Arcuate arteries dilated when the extracellular K+ concentration was raised to 8-10 mM from either zero or a normal physiological level of about 6 mM. The effect was not endothelium-dependent. Application of 0.01-1 mM Ba2+ to block inward rectifier K+ channels had no significant effect on K(+)-induced vasodilation in the arcuate artery, but under the same experimental conditions K(+)-induced dilation of the rat posterior cerebral artery was abolished by Ba2+. In the presence of 60 mM extracellular K+, inward rectifier K(+)-current was detectable in some single smooth muscle cells isolated from arcuate arteries but on average the current density was low (-1.44 pA pF-1 at -60 mV). K(+)-induced vasodilation of the arcuate artery was abolished by 10 microM ouabain and the half-effective concentration of K+ which induced vasodilation was 0.9-1.5 mM. CONCLUSIONS: The observations suggest that an increase in the extracellular K+ concentration (up to about 10 mM) dilates the rabbit renal arcuate artery and that the primary mechanism underlying the effect may be stimulation of Na(+)-K+ ATPase in the smooth muscle cell membrane. Inward rectifier K+ channels have a low average density in smooth muscle cells isolated from arcuate arteries and play no significant role in K(+)-induced vasodilation.

Animals↗
PubMed1997

Evaluation of a PCR assay for identification and differentiation of Campylobacter fetus subspecies.

OBJECTIVE: To evaluate a polymerase chain reaction assay for identification of Campylobacter fetus and differentiation of the defined subspecies. DESIGN: Characterisation of bacterial strains by traditional phenotyping, polymerase chain reaction, a probabilistic identification scheme and macrorestriction profiling using pulsed field gel electrophoresis. PROCEDURE: The results of identification of 99 bacterial strains as determined by conventional phenotyping or by polymerase chain reaction were compared. Two of these were type strains of C fetus subsp fetus and C fetus subsp venerealis; the remaining strains were field isolates putatively identified as C fetus. In cases where the subspecies identity was disputed, isolates were identified by means of a probabilistic identification scheme and by macrorestriction profiling. RESULTS: The agreement between strain identities initially suggested by traditional phenotypic methods and the PCR assay was found to be 80.8%. The polymerase chain reaction proved to be a reliable technique for the species and subspecies identification of C fetus; equivocal results were obtained in only two instances. Initial misidentifications by conventional phenotyping methods were attributed to methodological differences used in various laboratories. CONCLUSION: Our results indicate that misidentification of C fetus in routine diagnostic laboratories may be relatively common. The PCR assay evaluated gave rapid and reproducible results and is thus a valuable adjunctive method for the identification of C fetus and subsequent subspecies differentiation.

Animals↗
PubMed1996

Needs assessment of community-based services for children and youth with emotional or behavioral disorders and their families: Part 1. A conceptual model.

Communities throughout the nation are attempting to develop comprehensive systems of community-based, interagency care for children and youth with emotional or behavioral disorders and their families. Needs assessment has been identified as a key component of these initiatives. A needs assessment provides system planners with the data needed to make informed decisions with regard to improving the current system of care. In this first of a two-article series, an overview is presented of a model needs assessment designed for implementation by an interagency coalition interested in developing a comprehensive system of community-based services for children and youth with emotional or behavioral disorders and their families. Major components of the model include foundations for needs assessment, data collection, and data utilization.

Adolescent↗
PubMed1996

Needs assessment of community-based services for children and youth with emotional or behavioral disorders and their families: Part 2. Implementation in a local system of care.

In a previous article, rationale and procedures were presented for a model needs assessment of community-based services for children and youth with emotional and behavioral disorders and their families. In this article, the authors describe initial needs assessment planning activities, examine the implementation of the proposed model, provide a general overview of the results, and review how the community that conducted the assessment used the information to identify system development priorities and action plans. Quantitative data are provided on the population demographics and parent and direct services provider surveys. Qualitative data are presented on the semistructured interviews with key stakeholders and direct service providers.

Adolescent↗
PubMed1996

The association of elder abuse and substance abuse in the Illinois Elder Abuse System.

This article explores the role of abuser substance abuse in 552 cases of substantiated elder abuse in Illinois. When the abuser was identified as having a substance abuse (SA) problem, the type of elder abuse substantiated was more likely to involve either physical or emotional abuse than neglect or financial exploitation. Abusers with SA problems were more frequently men and children of their victims, and less likely to be caregivers. Abuser SA was associated with victim SA. Cases involving abusers with SA problems were more likely to be evaluated by case workers as having a high potential risk for future abuse. Elder abuser case workers should be trained to identify both victim and abuser SA and appropriate intervention strategies.

Aged↗
PubMed1996

Folate and vitamin B12 status of the elderly.

OBJECTIVE: The present study was undertaken to investigate the relationship between estimated folate and vitamin B12 intakes and their biochemical status in elderly persons. SUBJECTS: Twenty-eight males and 30 females ( > 65 years) were randomly selected from a larger sample of free-living elderly residents of Edmonton, Canada. Subjects were contacted through a seniors' service organization. Any subject using vitamin supplements or alcohol other than the social drink was excluded from the study. DESIGN: Dietary intake was estimated using a three-nonconsecutive-day food record. Biochemical status was assessed by measuring the plasma levels of folate and vitamin B12, as well as the red blood cell (r.b.c.) folate levels. RESULTS: Average daily intakes of both folate and vitamin B12 met the recommended requirements. Their mean plasma levels were within the accepted normal ranges in both males and females. However, probability analysis of dietary intake revealed an appreciable number of subjects at risk of deficiency, especially of folate (male 26%; female 21%). According to the interpretive guidelines of r.b.c. folate levels, an appreciable number of the study subjects were also found to be at risk of folate deficiency (male 57%; female 67%). CONCLUSIONS: The folate status appears to be a greater concern than the vitamin B12 status for the elderly population. It seems that although mean values of dietary intake and plasma concentrations of folate may indicate nutritional adequacy, a proportion of the older population may still be at nutritional risks.

Aged↗
PubMed1995

Non-radioactive localization of nucleic acids by direct in situ PCR and in situ RT-PCR in paraffin-embedded sections.

Technological developments have made possible extension of polymerase chain reaction (PCR) analysis to individual cells to localize DNA/RNA with non-radioactive labels at the light microscopic level. This approach, in situ PCR, is particularly useful in resolving low-frequency message expression in mixed populations of cells and tissues. We have established a working protocol for direct in situ PCR and have utilized several controls to validate our results. In this report we outline the procedures for detecting either DNA or RNA in a rapid and reproducible manner. We evaluate the sequential steps required for this analysis, such as protease hydrolysis, DNAse digestion, "hot start" capabilities, and detection methods. We have applied these methods in several applications, including detection of the p53 gene in human tumor samples, localization of insulin-like growth factor-IA mRNA in cell lines with low levels of expression, and distribution of transferrin mRNA in lung cancer cell lines and tumors. We demonstrate from this study that the in situ PCR technique is an investigative approach capable of detecting specific DNA/RNA sequences at the cellular level and of identifying cells with low levels of mRNA expression.

Base Sequence↗
PubMed1994

The role of the insulin-like growth factor I receptor in the transformation by simian virus 40 T antigen.

Balb/c 3T3 cells transformed by the tsA58 temperature-sensitive (ts) mutant of SV40 large T antigen, BalbA58 cells, grow in 1% serum at the permissive temperature of 34 degrees C but fail to grow at the restrictive temperature of 39.6 degrees C. Although incapable of growing, BalbA58 cells, in low serum at 39.6 degrees C, still synthesize DNA and tend to accumulate in the G2 phase of the cell cycle. Growth in 1% serum at 39.6 degrees C resumes if BalbA58 cells are treated with insulin-like growth factor I (IGF-I). By using cells overexpressing the IGF-I receptor, and cells with a targeted disruption of the IGF-I receptor genes, we show that: 1) the activation of the IGP-I receptor by its ligand(s) plays a major role in the ability of the SV40 large T antigen to promote growth in low serum; and 2) the IGF-I receptor plays a role in the progression of cells not only through G1, but also through the S and G2 phases of the cell cycle. These findings, together with other recent findings from the literature, suggest that one of the mechanisms by which oncogenes and tumor suppressor genes regulate cell growth is through the modulation of growth factors and their receptors.

3T3 Cells↗
PubMed1993

Scientific basis for cancer prevention. Intermediate cancer markers.

Promising cancer clinical trials results involving the disruption of early stages of cancer with intervention agents such as tamoxifen or retinoids have led to significant new research interest in developing preventative strategy for the control of epithelial cancers. Key to the efficient progress in this field is a clear understanding of the complex biology of the early stages of cancerization that proceed on the epithelial surface. Systematic analysis of the biology of strategic targets such as growth factors is one approach to this problem. Gastrin-releasing peptide is an autocrine growth factor for certain types of lung cancer cells. Mechanisms involved in the production and activation of this peptide are discussed as an example of how rational approaches to neutralization of cancer promotion biology can be achieved. The tools to monitor the success of this type of intervention also emerge from the understanding of the biology of growth factors, and intermediate end point markers that determine the presence or effects of a growth factor are attractive candidates for evaluation. Additional biologic tools reflecting the early stages of the cancer process need to be validated for use in serially evaluating the status of the relevant epithelium so that the ongoing success of a cancer intervention procedure can be established. Through this type of translational research, important applications of molecular biology may greatly improve the success of preventative strategies for cancer control.

Anticarcinogenic Agents↗
PubMed1993

A support group for people bereaved through suicide.

Although much research has been performed in recent years on the prevention of suicide, less attention has been focused on helping the persons left behind. This article outlines the history of establishing a support group for people who have been bereaved through suicide in an Australian city. It describes the difficulties in establishing the group, its structure, management, and helping functions, and the experiences gained from the initial 7 years of operation. The article has been written in response to requests from medical, social, and lay agencies for information in establishing similar support groups.

Adaptation, Psychological↗
PubMed1993

Morphine elimination and hepatic blood flow--a study in patients with portal hypertension.

To investigate the influence of changes in portal venous blood flow on the clearance of morphine, the elimination of a single intravenous dose of morphine sulphate was studied in twelve patients with periportal fibrosis undergoing distal splenorenal shunt for portal hypertension. All patients had almost normal preoperative liver function. Six patients (Group A) received morphine after induction of anesthesia but before surgery; a further six patients (Group B) received morphine after completion of the splenorenal shunt and removal of all vascular clamps. Blood was sampled for 24 hours after morphine administration and analysed for plasma morphine concentration using high performance liquid chromatography. The maximum concentration of morphine was significantly greater in those patients in Group B who received morphine after the shunt (P < .002). Clearance of morphine during the operation was also significantly reduced in these patients compared with the initial clearance (before release of the clamps) in Group A (P < .004). As a consequence of these changes the AUC was greater in this group (P < 0.004). However, there were no differences with the elimination rates after surgery had finished. The results suggest that in individuals with normal liver function, the clearance of morphine is dependent on hepatic blood flow.

Adult↗
PubMed1992

A population-wide profile of prescription drug use in Saskatchewan, 1989.

OBJECTIVE: To measure the prevalence of prescription drug use in Saskatchewan in 1989. DESIGN: Retrospective study. PARTICIPANTS: A total of 961,203 Saskatchewan residents (including those who died or were born during the study year) who were eligible for coverage under the Saskatchewan Prescription Drug Plan. The study population represented 94% of the province's total population; those excluded were mostly status Indians (for whom a federal plan is available). MAIN RESULTS: At least one prescription was received by 66.0% of the study population in 1989. The mean number of prescriptions per patient was 8.2, and the mean cost of drug material per prescription was $13.95. Females received substantially more prescriptions than males; the difference was particularly notable for cardiovascular agents, antidepressants and benzodiazepines. In the senior population 80.8% received at least one prescription; the mean number of prescriptions per patient was 18.4. The most commonly dispensed drug for the entire study population was amoxicillin (290 prescriptions per 1000 people); triazolam was the most frequently dispensed central nervous system drug (74 prescriptions per 1000 people). Regional variation in overall drug use was remarkably small, although it increased at the drug-class level, especially for tranquillizers. The use of cardiovascular drugs was 27% to 32% higher (depending on how use was measured) per Regina resident than per Saskatoon resident. Benzodiazepines were commonly used on a long-term basis, despite recommendations to the contrary. CONCLUSIONS: The results quantify the prevalence of prescription drug use, underscore the importance of careful management of drug therapy by physicians and pharmacists (especially for seniors), illustrate substantial variation in drug therapy strategies and raise questions about utilization of benzodiazepines and cardiovascular drugs.

Age Factors↗
PubMed1992

Candidate biomarkers for application as intermediate end points of lung carcinogenesis.

The need for validated intermediate end point markers to facilitate lung cancer chemointervention research is compelling. Three major classes of lung markers are relevant for this application. Since lung cancer includes four distinct histologies, markers that map degrees of histologic differentiation are important. Many of the markers for squamous differentiation overlap with the candidates for application in the study of head and neck cancer. Production of tissue-specific cell products especially for surfactant or CEA is of interest, because the gene structure is known and many differentiation-related polymorphisms exist. This strategy would be useful for adenomatous type tissue. A second type of marker is the broad group of differentiation markers. The carbohydrate or blood group-like antigens comprise a representative example. Carbohydrate structures are expressed in a specific sequence during fetal processes, and this sequence appears to reverse with the development of a cancer. Retrodifferentiation of specific differentiation markers is the basis of a major effort to effect earlier lung cancer detection using sputum immunocytochemistry. The final class includes markers which affect either positive or negative aspects of growth. Candidates in this area include growth factors or their receptors, or genes that regulate growth. If the intermediate end point marker reflects tumor biology and that biology is in the causal path of tumor progression, serial observation of that parameter should indicate the success of the intervention. In all three of these examples, the clinical material to be analyzed could be sputum specimens, bronchial biopsies or resected lung tissue. Systematic analysis of these markers in context of intervention trials is required to validate their utility.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗