Search PubMed⌕ Search

Biomedical subjects

M Woods

Publications and source records attributed to M Woods.

At least 37 records · Page 2Linked to original sources
PubMed2000

Revisiting Currie--how low can you go?

Over the years many different formulae have been proposed to derive the 'limits of detection' for radiometric measurements. With the ever increasing employment of quality systems within the radioanalytical laboratory, it is vital that the term 'limit of detection' is well understood and defined in the documentation in use within the laboratory. This paper reviews the various formulae used to derive a limit of detection, most of which claim to be derived from Currie's landmark paper of 1968, which set out in detail the means by which the analyst can arrive at a limit of detection and limit of determination. However, with the vastly increased computing power available to the analyst, coupled with the off-the-shelf availability of low and zero background detectors, it is now more straightforward to arrive at exact solutions to define limits of detection and determination. Finally, we set out some examples of decision making at these limits and how this may inform the way in which detector time is allocated for the measurement of samples containing low levels of radioactivity.

Journal Article↗
PubMed2000

Lyn and syk tyrosine kinases are not activated in B-lineage lymphoid cells exposed to low-energy electromagnetic fields.

Exposure of B-lineage lymphoid cells to a 100 microT 60 Hz AC magnetic field has been reported to stimulate the rapid activation of Lyn and Syk tyrosine kinases and the induction of protein tyrosine phosphorylation. These findings are significant because of the critical role played by these B cell signaling events in the control of growth and differentiation, and therefore the potential of electromagnetic field (EMF) exposure to induce cancer. We report the first study carried out with the aim of reproducing the reported EMF effects on Lyn and Syk tyrosine kinases. The system used enabled EMF exposure conditions to be carefully controlled and also allowed experiments to be performed blind. The effects of a 100 microT 60 Hz AC magnetic field on protein tyrosine phosphorylation and on Lyn and Syk tyrosine kinase activities were investigated in Nalm-6 and DT40 B cells in the absence and presence of a 46 microT DC magnetic field. However, no significant effects of low-energy electromagnetic fields on tyrosine kinase activities or protein phosphorylation were observed.

B-Lymphocytes↗
PubMed2000

Cyclic AMP regulates cytokine stimulation of endothelin-1 release in human vascular smooth muscle cells.

Exposure of human vascular smooth muscle cells (HVSMCs) to cytokines markedly elevates endothelin-1 (ET-1) mRNA expression and peptide production. Cyclic AMP is a key regulator of many physiological processes. The aim of this study was to determine whether an elevation of intracellular cAMP may affect cytokine-induced production of ET-1 in HVSMCs. Cicaprost, a prostacyclin analogue, forskolin, an activator of adenylate cyclase, and Ro-20-1724, a phosphodiesterase type IV inhibitor, inhibited cytokine-stimulated ET-1 release in a concentration-dependent manner. Ro-20-1724 also inhibited cytokine-induced upregulation of preproendothelin-1 mRNA expression in saphenous vein (SV) vascular smooth muscle cells (VSMCs). These findings demonstrate that ET-1 mRNA expression and peptide production is modulated by elevations in cAMP levels. Further studies are necessary to elucidate which other pathways may be involved in the regulation of cytokine-stimulated ET-1 release from HVSMCs.

4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone↗
PubMed2000

Signal transduction pathways involved in cytokine stimulation of endothelin-1 release from human vascular smooth muscle cells.

Endothelin-1 (ET-1) mRNA expression and peptide production in human vascular smooth muscle cells (HVSMCs) are markedly increased by exposure to cytokines. As the transcription factor nuclear factor-kappaB (NF-kappaB) often mediates the effects of cytokines in target cells the aim of this study was to determine whether the production of ET-1 following exposure of HVSMCs to cytokines depends upon activation of NF-kappaB. BAY 11-7082, an inhibitor of cytokine-induced inhibitor protein (IkappaB) phosphorylation, inhibited cytokine-stimulated upregulation of preproendothelin-1 mRNA expression and ET-1 peptide production. In addition, immunoblotting showed that cytokine stimulation of ET-1 release in VSMCs involves nuclear translocation of NF-kappaB. In conclusion, NF-kappaB activation is involved in the stimulation by cytokines of ET-1 release from HVSMCs. As upregulated production of ET-1 within VSMCs may underlie the causative role of ET-1 in a number of disease states this finding indicates that NF-kappaB within HVSMCs could be central to a number of vascular pathologies.

Cells, Cultured↗
PubMed2000

The prostacyclin-mimetic cicaprost inhibits endogenous endothelin-1 release from human pulmonary artery smooth muscle cells.

There is increasing evidence supporting a role for endothelin-1 (ET-1) in human pulmonary hypertension. The aim of this study was to determine the relative roles of human pulmonary microvascular endothelial cells (HPMVE) and human pulmonary artery smooth muscle (HPASM) cells to produce ET-1 under inflammatory conditions and to investigate further possible control mechanisms of ET-1 production by HPASM. Although HPMVE cells produced more ET-1 than HPASM when cultured with fetal calf serum (FCS) alone and after treatment with cytokines; HPASM produced significant amounts of ET-1 after stimulation with cytokines. Cytokine-stimulated increase in ET-1 production by HPASM was inhibited by cicaprost, a prostacyclin analogue, and other agents that are known to increase intracellular cyclic AMP. Cicaprost also inhibited proliferation of HPASM in response to FCS lending support to the theory that part of the clinical benefit seen in long-term treatment with prostacyclin in pulmonary hypertension may be a result of inhibition of ET-1 production in these cells.

Cell Division↗
PubMed2000

Finishing occlusion, degree of stability and the PAR index.

The occlusions of sixty-five patients, treated by one private specialist orthodontist with consistent philosophy and goals, were assessed according to the PAR Index. For each patient, pre-treatment, post-treatment and follow-up study models were assessed. Follow-up models were taken at least 6.5 years following the removal of all retention appliances. Mean-weighted PAR scores were calculated for the total sample and various sub-groups at each stage. Mean percentage changes in weighted PAR scores were also calculated. The relationships between the occlusal standards at the end of active treatment and at the end of the follow-up period, and specific diagnostic and treatment factors were then investigated to search for any factors that might be predictive of long-term post-treatment occlusal stability or instability. The overall mean-weighted pre-treatment, post-treatment and follow-up PAR scores were 25.5, 3.0 and 7.0, respectively. There was an 85.6 per cent decrease with treatment in the overall mean-weighted PAR score. This was followed by a 15.2 per cent increase in that overall mean during the follow-up period. In this introductory study, neither the PAR score at the end of active treatment, nor the amounts of occlusal change occurring during or after active treatment, were found to be predictive of the amount of post-treatment occlusal change.

Adolescent↗
PubMed2000

Vertical facial pattern and orthodontic stability. Part I: Pretreatment vertical pattern and stability.

The occlusions of sixty patients treated by one experienced orthodontist were assessed using the PAR Index. For each patient, pretreatment, post-treatment and long-term follow-up study casts were examined. Follow-up casts were taken at least 6.5 years following the removal of all retention appliances. Following pretreatment cephalometric analysis, the patient sample was divided into three vertical facial subgroups according to the Jarabak Facial Height Quotient. Mean weighted PAR scores were then calculated at each stage for the total sample and for the three subgroups. Mean absolute and percentage occlusal changes were also calculated for the post-treatment period. The relationship between post-treatment occlusal change and pretreatment vertical facial pattern was then studied. The mean weighted pretreatment, post-treatment and follow-up PAR scores were 27.3, 3.3 and 8.0, respectively. The mean-absolute and percentage post-treatment increases in weighted PAR score were 4.7 and 25.4, respectively. No statistically-significant relationship could be found between the pretreatment vertical facial pattern and changes occurring in the weighted PAR score during the follow-up period. It was concluded, therefore, that pretreatment vertical facial pattern, at least on its own, is not likely to be predictive of the amount of post-treatment occlusal change.

Adolescent↗
PubMed2000

Vertical facial pattern and orthodontic stability. Part II: Facial axis changes and stability.

Lateral cephalograms and study casts of 55 patients were evaluated to determine if any relationships exist between Facial Axis changes occurring during and after active treatment and either the pretreatment Jarabak Facial Height Quotient or the amount of post-treatment occlusal change, as measured with a weighted PAR score. No significant relationships could be found. There was instead a wide range of individual variation in the post-treatment behaviour of both the Facial Axis and the weighted PAR score, in both the total sample and three Jarabak Facial Height subgroups. Long-term Facial Axis changes occurring in individual patients, however, were not necessarily associated with occlusal deterioration. Since the Facial Axis is likely to change to some extent in the long-term, it was suggested that widely recommended methods for Facial Axis control during treatment should be considered primarily for functional and aesthetic reasons, rather than on the basis of directly ensuring long-term occlusal stability.

Adolescent↗
PubMed1999

Diagnosis of Chlamydia trachomatis and Neisseria gonorrhoeae. Genitourinary infections in males by the Amplicor PCR assay of urine.

The Amplicor CT/NG polymerase chain reaction (PCR) test on urine specimens from males was prospectively evaluated against established specimens and laboratory methods for diagnosing Chlamydia trachomatis and Neisseria gonorrhoeae genitourinary infections, in patients from a remote region of Western Australia. Seventy-three males who were tested for both C. trachomatis and N. gonorrhoeae by both conventional methodology and Amplicor PCR on urine were enrolled in the study. Established testing comprised enzyme immunoassay/immunofluorescence antigen testing (EIA/IF) for C. trachomatis and microscopy and/or culture for N. gonorrhoeae on urethral swabs. Positive test results were confirmed using a set of criteria that included supplemental PCR testing and clinical history. Overall, 13.7% of patients were resolved as positive for C. trachomatis and 52.1% as positive for N. gonorrhoeae. The sensitivity and specificity of the Amplicor CT/NG PCR on male urine specimens for C. trachomatis were 80.0% (8/10) and 95.2% (60/63), compared with 60.0% (6/10) and 100.0% (63/63) for EIA/IF on urethral swabs. For N. gonorrhoeae, the sensitivity and specificity of the Amplicor CT/NG PCR on male urine specimens were both 100% (38/38 and 35/35, respectively) compared with 86.8% (33/38) and 100% (35/35) for microscopy and/or culture on urethral swabs. The results of this study indicate that the Amplicor CT/NG multiplex PCR test for C. trachomatis and N. gonorrhoeae performed on urine in males provides a highly sensitive, specific, and robust method for the diagnosis of both C. trachomatis and N. gonorrhoeae, for the early detection of both symptomatic and asymptomatic infected individuals.

Chlamydia Infections↗
PubMed1999

A nursing ethic: the moral voice of experienced nurses.

Nursing acts occur in thousands of instances daily, being a major component of professional health care delivery in institutions, communities and homes. It follows that the ethical practice of most nurses is put to the test on an everyday rather than an occasional basis. Hence, within nursing practice there must be a rich and deep seam of reflective interpretation and practical wisdom that is 'embedded' within the experiences of every experienced nurse. This article presents discussion on some of the main findings of a recently completed study on nursing ethics in New Zealand. An interpretation of a nurse's story taken from the study is offered and suggestions are made for nursing ethics education.

Conflict, Psychological↗
PubMed1999

Endothelin-1 is induced by cytokines in human vascular smooth muscle cells: evidence for intracellular endothelin-converting enzyme.

Endothelin-1 (ET-1) is the predominant endothelin isopeptide generated by the vascular wall and therefore appears to be the most important peptide involved in regulation of cardiovascular events. Many pathologic conditions are associated with elevations of ET-1 in the blood vessel wall. Because these conditions are often cytokine driven, we examined the effects of a mixture of cytokines on ET-1 production in human vascular smooth muscle cells (VSMCs) derived from internal mammary artery and saphenous vein (SV). Incubation of IMA and SV VSMCs with tumor necrosis factor-alpha (10 ng/ml) and interferon-gamma (1000 U/ml) in combination for up to 48 h markedly elevated the expression of mRNA for prepro-ET-1 and the release of ET-1 into the culture medium. This cytokine-stimulated release of ET-1 was inhibited by a series of dual endothelin-converting enzyme (ECE)/neutral endopeptidase inhibitors, phosphoramidon, CGS 26303, and CGS 26393, with an accompanying increase in big ET-1 release but with no effect on expression of mRNA for prepro-ET-1. These same compounds were 10 times more potent at inhibiting the conversion of exogenously applied big ET-1 to ET-1. ECE-1b/c mRNA is present in SV VSMCs, however no ECE-1a is present in these cells. Thus VSMCs most probably contain, like endothelial cells, an intracellular ECE responsible for the endogenous synthesis of ET-1. Under the influence of pro-inflammatory mediators the vascular smooth muscle can therefore become an important site of ET-1 production, as has already been established for the dilator mediators nitric oxide, prostaglandin I2, and prostaglandin E2.

Aspartic Acid Endopeptidases↗
PubMed1999

Comparison of the potassium channel openers, WAY-133537, ZD6169, and celikalim on isolated bladder tissue and In vivo bladder instability in rat.

The effects of the ATP-dependent potassium channel agonists ZD6169, celikalim, and WAY-133537 on bladder contractile function were examined in vitro on isolated bladder strips and in vivo on spontaneous bladder contractions. All three compounds produced a concentration-dependent relaxation of isolated rat detrusor strips (IC50 values = 0.93, 0.03, and 0.09 microM, respectively for ZD6169, celikalim, and WAY-133537. Contractile inhibition by all three compounds was fully reversed by 6 microM glyburide. These compounds also effectively inhibited spontaneous bladder contractions in the rat hypertrophied bladder model of detrusor instability. We also examined the electrophysiological properties of WAY-133537 on isolated rat bladder detrusor myocytes. Myocytes had an average resting membrane potential of -40 mV. Under patch current-clamp conditions, WAY-133537 (0.3 and 1.0 microM, n = 4-5) produced a significant hyperpolarization of 21 and 26 mV, respectively. Hyperpolarization was reversed by the addition of 5 microM glyburide. In patch voltage-clamp studies, WAY-133537 (0.3 microM, n = 3) significantly increased outward current in response to both voltage step and ramp protocols consistent with activation of the ATP-dependent potassium channel. In the detrusor instability model, WAY-133537 and celikalim had similar oral potencies (ED50 = 0.13 and 0.3 mg/kg, respectively), whereas ZD6169 was less potent (ED50 = 2.4 mg/kg). The antihypertensive agent celikalim exerted effects on the bladder at doses that significantly reduced systemic blood pressure. In contrast, both WAY-133537 and ZD6169 inhibited bladder hyperactivity at doses that produced minimal changes in both mean arterial blood pressure and heart rate. These data suggest that both WAY-133537 and ZD6169 may be useful in the treatment of bladder instability at doses associated with minimal hemodynamic side effects.

Amides↗
PubMed1999

An assessment of urethral catheter valves.

Catheter valves have rarely been compared with conventional urinary drainage systems. Valves may only be suitable for certain patients. Patients should be counselled on the use and choice or combination of systems.

Adult↗
PubMed1999

Chronic alcohol consumption during male rat adolescence impairs skeletal development through effects on osteoblast gene expression, bone mineral density, and bone strength.

BACKGROUND: The effect of chronic alcohol ingestion on bone formation is mediated through its direct actions on osteoblasts. The affected population of mature osteoblasts declines in both number and function resulting in decreased cancellous bone volume and cortical bone strength. Although the mechanism of action on osteoblasts is unknown, alcohol alters osteoblast gene expression and matrix synthesis. METHODS: Male rats consuming alcohol (EtOH) daily for 60 days from 35 days of age until 95 days of age (unrecovered group) were compared to rats switched to a regular diet of rat chow without EtOH for an additional 90 days (recovered group). The effects of chronic dietary EtOH on skeletal development during adolescence were examined in the unrecovered and recovered rats by hormonal analysis, bone mineral density determination, bone histomorphometry, metaphyseal gene expression for osteoblast-specific proteins, and biomechanical analysis. RESULTS: The unrecovered EtOH imbibing rats weighed less than their paired isocaloric-fed and ad libitum mates. Statistically significant reductions occurred in femur lengths in the unrecovered EtOH-fed group compared to controls. Serum testosterone levels were significantly decreased by EtOH consumption but returned to higher normal levels during the recovery period. Serum insulin-like growth factor-1 (IGF-1) levels were unaffected by EtOH. Serum osteocalcin levels in the unrecovered EtOH-fed group were higher than those in the recovered group but EtOH intake did not elevate the unrecovered levels compared to isocaloric or ad libitum control rats. Quantitative computed tomography (QCT) determination of bone mineral density (BMD) revealed a statistically significant reduction only in the distal femur metaphysis in the unrecovered EtOH-fed rats. BMD increased during recovery in the distal femur metaphysis and femur mid-cortex. Image analysis of midsagittal sections of the proximal tibial metaphysis of unrecovered rats revealed reductions in cancellous area, trabecular cellularity and thickness, and increased trabecular separation. Cortical widths were significantly reduced by chronic EtOH consumption. These changes remained statistically significant at the end of the recovery period. Four-point biomechanical testing of femurs from EtOH-fed and control unrecovered groups revealed significant reductions in cortical strength, energy-to-failure, and stiffness. These cortical characteristics returned to normal values with abstinence. Tibial metaphyseal alpha-1 type I collagen and osteocalcin mRNA expression levels were significantly elevated above the paired isocaloric control levels after 60 days of EtOH consumption. Metaphyseal alkaline phosphatase mRNA levels remained unaltered by EtOH consumption in the unrecovered group. After 90 days of abstinence alpha-1 type I collagen and alkaline phosphatase gene expression levels remained significantly elevated over the isocaloric and ad libitum control levels (collagen) and the isocaloric control value (alkaline phosphatase). However, metaphyseal osteocalcin mRNA levels declined to normal levels during abstinence. CONCLUSIONS: Chronic consumption of EtOH during the peripubertal period of skeletal growth leads directly to decreased metaphyseal and cortical bone mediated through effects on osteoblasts. Removal of EtOH from the diet is accompanied by incomplete restoration of normal bone metabolism during skeletal growth.

Age Factors↗
PubMed1999

The community and orthodontic care. Part II: Community-perceived importance of correcting various dentofacial anomalies. Part III: Community perception of the importance of orthodontic treatment.

Part II. A professionally-managed telephone survey was undertaken to assess the community-perceived importance of correcting various dentofacial anomalies. The sample included 505 respondents, aged eighteen and over, from metropolitan and non-metropolitan households across the state of Victoria. The sample distribution had a 95 per cent confidence limit with a 5 per cent margin of error and closely matched the known population distributions for age, sex and geographical location. This article forms part two of a series. It was found that the correction of functional problems such as "difficulty chewing or speaking" was considered to be very important, regardless of age, sex or geographical area. The correction of other factors such as "top teeth which stick out in front", "bottom teeth which stick out in front" or "crooked or crowded front teeth" was also considered to be important. "Spaced front teeth" was the factor considered least important for correction within all groups. It is interesting to note that, for all factors, correction seemed to be considered more important by females and non-metropolitan respondents than by males and metropolitan respondents, In contrast to previous studies in which it has been suggested that patients seek treatment mainly for reasons of aesthetics, the results of this study have shown a definite community recognition of the importance of functional problems as well. Part III. A professionally-managed telephone survey was undertaken to assess the community's perceptions of the importance of having "straight teeth and a nice smile", to assess if a Medicare (the Australian government health benefit scheme) rebate should be provided for orthodontic treatment and to assess whether respondents had any private health insurance that would help cover the cost of orthodontic treatment. The sample included 505 respondents, aged eighteen and over,, from metropolitan and non-metropolitan households across the state of Victoria. The sample distribution had a 95 per cent confidence limit with a 5 per cent margin of error and closely matched the known population distributions for age, sex and geographical location. It was found that a very large percentage of respondents considered the need for "straight teeth and a nice smile" to be very important. This finding is supported by the many studies showing the importance of facial attractiveness to the lives of all people, young and old. Only a small percentage of respondents indicated that they had any private dental health insurance that would help cover the cost of orthodontic treatment. Efforts should be made to inform those responsible for the planning of orthodontic services in both the public and private sectors of the importance of the community's perceptions of aesthetics, and the large amount of published work that reinforces the impact of facial attractiveness on people's lives.

Adolescent↗
PubMed1999

The community and orthodontic care. Part I: community-perceived need and demand for orthodontic treatment.

A professionally managed telephone survey was undertaken to assess community-perceived need and demand for orthodontic treatment, and to determine the proportion of the community with a history of having some form of orthodontic treatment. The sample included 505 respondents, aged eighteen and over, from metropolitan and non-metropolitan households across the state of Victoria in Australia. The sample distribution had a ninety-five per cent confidence limit with a five per cent margin of error, and closely matched the known population distributions for age, sex and geographical location. From the survey it can be concluded that apparently forty-four per cent of Victorian families include someone who has already received some form of orthodontic treatment. Twenty-five per cent of the survey respondents perceived some need for the treatment of a family member; only fifteen per cent of respondents, however, reported that someone in their family actually wanted treatment. This survey has established baseline values for community perceived need and demand for orthodontic treatment. Use of these values should assist in future resource management within both the public and private sectors.

Adolescent↗
PubMed1999

Comprehensive treatment commenced in the mixed dentition and completed in the permanent dentition: an "early treatment" malocclusion.

The management of a ten-year-old female with an Angle Class II division 1 malocclusion is followed for nearly ten years, through active treatment, until follow-up some years later. Note is made of: the duration of the overall active treatment period; the need for considerable patient cooperation; the fact that the lower incisors did not move forward on their underlying bone while still moving forward in relation to the APo line; and the fact that, in this instance, the third molars were chosen as appropriate teeth for extraction.

Child↗