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M Giles

Publications and source records attributed to M Giles.

At least 37 records · Page 2Linked to original sources
PubMed1998

Gender differences in mediators of left ventricular hypertrophy in dialysis patients.

Left ventricular hypertrophy (LVH) is known to be a strong predictor of cardiovascular death in dialysis patients, but the mediators for its development remain to be clarified. In the non-renal population risk factors for LVH differ between the genders. We therefore studied 46 non-diabetic patients (26 male, 19 female) on maintenance hemodialysis (n = 25) or continuous ambulatory peritoneal dialysis (CAPD) (n = 20) all free from clinically evident cardiac disease, who underwent 48-hour ambulatory blood pressure (BP) monitoring, 2-D and M-mode echocardiography for left ventricular mass index (LVMI) and bloods for hemoglobin, parathyroid hormone (PTH), urea and electrolytes and liver function tests. Thirty-two out of 45 patients were taking antihypertensive drugs at the time of the study. The mean 48-hour BP was 135 +/- 19/83 +/- 13 mmHg and the mean LVMI was 144 +/- 50 g/m2. LVH (LVMI > 131 g/m2 men, > 100 g/m2 women) was present with equal frequency in both sexes: men 72% (18/25) and women 68% (13/19). Simple regression analysis showed that LVMI was correlated with 48-hour pulse pressure (r = 0.52, p < 0.00033), 48-hour systolic BP (r = 0.37, p < 0.05), PTH (r = 0.31, p < 0.04) and inversely with serum calcium (r = -0.29, p < 0.05) and hemoglobin (r = -0.33, p < 0.03). However, on multiple regression analysis pulse pressure (R2 = 28.7%), day systolic BP (R2 = 15.4%) and 48-hour systolic BP (R2 = 14.1%) were the only variables linked to LVMI. When the patients were split by gender, stepwise linear regression in the men showed a highly significant relationship between LVMI and pulse pressure (R2 = 37.1%) which was stronger at nighttime (R2 = 42.6%), but in females this was not apparent (R2 = 4.39%) and indeed no variable was linked to LVMI. Our study confirms that LVH is not only prevalent in dialysis patients but is present with equal frequency in both sexes. However the determinants of its development are different for each gender. In males pulse pressure, and therefore by implication vascular compliance, is important but in females, other unidentified factors predominate.

Adult↗
PubMed1997

A competitive ELISA for the serodiagnosis of hypodermosis.

Hypodermosis is a parasitic disease of cattle caused by Hypoderma lineatum and H. bovis. It is an important health and welfare problem of infested cattle and a cause of considerable economic loss. In live animals, detection can be either by direct clinical examination of infested cattle and palpation of second and third stage larvae in the back or by the use of serological methods. This paper describes a competitive ELISA for the detection of antibodies to Hypoderma species in cattle sera. It has been validated using a small panel of 40 samples from clinically positive cattle and 200 samples from clinically negative (unexposed) cattle from a warble free area. Sensitivity and specificity calculated from this panel were 100% and 92% respectively at 2 SD from the mean or 92.5% and 98.5% at 3 SD from the mean. The use of serology and direct clinical examination of affected cattle, are discussed as methods for monitoring hypodermosis. The competitive ELISA should prove a useful adjunct to the standard sandwich ELISA, particularly in the resolution of samples which display non-specific binding properties.

Animals↗
PubMed1997

Ontogeny of angiotensin II receptors, types 1 and 2, in ovine mesonephros and metanephros.

By RNAse protection assay, hybridization histochemistry, and in vitro autoradiography it was shown that both mRNA and protein for AT1 and AT2 receptors were present in ovine fetal meso- and metanephroi at 40 days of gestation (term approximately 150 days). AT1 mRNA was localized to presumptive mesangial cells of glomeruli at 40-, 75-, 131-gestational-day-old fetuses and two-day-old lambs, in addition to being widely present in interstitial cells of the cortex and medulla, once these zones formed (60 days). By two days after birth the medullary AT1 distribution was confined to the inner stripe of the outer medulla. AT2 mRNA was present in peripheral interstitial/tissue of the mesonephros, and interstitial tissue surrounding developing glomeruli, but not the outermost nephrogenic mesenchyme in the metanephros from 40 to approximately 131 days (the period of active nephrogenesis). In addition, AT2 mRNA was localized to epithelial cells of the macula densa in metanephroi (40 to 131 gestational days) during, but not after completion, of nephrogenesis. These studies suggest that angiotensin II (Ang II) could have differentiating effects, via AT1 receptors, from very early in development. The unique epithelial site of AT2 expression in the macula densa raises the possibility that Ang II may play a role in the invariant positioning of the macula densa at the pole of its glomerulus, via this receptor.

Aging↗
PubMed1997

The effect of dietary sodium on calcium metabolism in premenopausal and postmenopausal women.

OBJECTIVE: To investigate the effects of high and low sodium diets on urinary calcium, bone turnover and calcium absorption in pre and postmenopausal women. DESIGN: Experimental, prospective and longitudinal study. SETTING: Samples were taken at the hospital and the diets were followed at home. SUBJECTS: Volunteers were recruited from the hospital and were either hospital staff or post-graduate students. No volunteers failed to complete the study but one was omitted from analysis due to lack of compliance. INTERVENTIONS: Eleven healthy premenopausal women aged 22-47 y and 11 healthy postmenopausal women ages 45-70 y followed a high (300 mmol/d) and a low (50 mmol/d) sodium diet for one week each. On the 7th day of each diet, blood and urine samples were taken. RESULTS: On the high sodium diet 24 h urinary sodium and calcium values relative to creatinine were significantly higher for all subjects (P < 0.05). Postmenopausal women on the high sodium diet had biochemical evidence of increased bone resorption in relation to the low sodium diet. However in premenopausal women there was no such change. Calcium absorption did not change significantly in either group. CONCLUSIONS: It appears that postmenopausal, but not premenopausal, women respond to a high sodium diet by an increase in bone resorption which may lead to reduced bone density. SPONSORSHIP: Arthritis and Rheumatism Council Project Grant R44.

Absorption↗
PubMed1997

An analysis of Michigan and California CO remote sensing measurements.

Remote sensing measurements of CO emissions from onroad vehicles were made in California in 1991 and in Michigan in 1992. It was determined that both fleets had a small linear increase in the high emitter frequency (vehicles emitting more than 4% CO) as a function of vehicle age for 1986 and newer model vehicles. Although high emitting vehicles were only a small minority of the fleet, they had a dominant impact on the mean CO and total CO emitted by the fleet. In Michigan, the highest emitting 5% of passenger cars generated 45% of the CO from cars. In California, the highest emitting 5% of passenger cars generated 38% of the CO from cars. There was a high correlation between the mean CO emitted by each model year of vehicle and the frequency of high emitting vehicles within the model year for both the Michigan and California fleets. The frequency of high emitters within any model year had no obvious relation to that model year's certification standards. The high emitter frequencies for vehicles less than nine years old were very similar for the California and Michigan fleets. An increase in the high emitter frequency in the ten-year-old and older Michigan passenger car fleet (relative to the California passenger car fleet), suggests, but does not conclusively demonstrate, that the rate of high emitters in Michigan and California is reduced by the inspection and maintenance (I/M) programs.

Automobiles↗
PubMed1997

Interdialytic weight gain and 48-h blood pressure in haemodialysis patients.

BACKGROUND: Hypertension, which is often associated with hypervolaemia, is common in haemodialysis patients and is a known determinant of target organ damage. Interdialytic weight gain due to volume overload has also been associated with mortality in haemodialysis patients. METHODS: We therefore studied 27 chronic haemodialysis patients who underwent 48-h ambulatory blood pressure monitoring between two midweek dialysis sessions, and 2D and M-mode echocardiography for determination of left ventricular mass index. RESULTS: Left ventricular hypertrophy (left ventricular mass index in men > 131 g/m2, women > 100 g/m2) was present in 70% (19/27) patients despite a mean 48-h blood pressure of 132 +/- 19/81 +/- 15 mmHg. Mean interdialytic weight gain was 1.6 +/- 0.8 kg and was not related to left ventricular mass index. Two patterns of interdialytic blood pressure change were apparent: in group 1 (16 patients) 48-h blood pressure increased (+19 +/- 12/13 +/- 9 mmHg), whereas in group 2 (11 patients) blood pressure fell (-10 +/- 13/-8 +/- 10 mmHg P < 0.0001). In both groups the number of hypertensive patients (group 1, 10/16; group 2, 6/11), the 48-h blood pressure (132 +/- 20/80 +/- 15 vs 132 +/- 18/82 +/- 15 mmHg) and interdialytic weight gain (+1.9 +/- 0.7 vs +1.3 +/- 0.7 kg) were similar. There was also no correlation between interdialytic blood pressure change and weight gain in either group. CONCLUSIONS: We conclude that interdialytic blood pressure changes cannot be directly related to interdialytic fluid gain, even in apparent volume-dependent hypertension, emphasizing the importance of additional factors in the control of blood pressure in end-stage renal disease.

Adult↗
PubMed1997

Left ventricular hypertrophy and ambulatory blood pressure monitoring in chronic renal failure.

BACKGROUND: Left ventricular hypertrophy (LVH) is both common and an important predictor of risk of death in end-stage renal failure (ESRF). In mild to moderate chronic renal failure (CRF), the timing of onset of LVH and the factors involved in its initial development have not been fully elucidated. The present study was undertaken to examine the prevalence and potential determinants of echocardiographically determined LVH in this connection, and to compare 24-h ambulatory blood pressure (BP) recordings with BP measured at a previous clinic visit. METHODS: From a cohort of 120 non-diabetic patients who had been attending a nephrology clinic, 118 agreed to participate in the study. Of these we selected for analysis 85 stable patients (37 male). Patients with known cardiovascular disease, those with a history of poor compliance with antihypertensive medication, and those in whom such medication had been changed in the previous 3 months were excluded. Clinic BP, 24-h ambulatory BP, echocardiography, body mass index (BMI), serum creatinine (SCr), creatinine clearance (CrCl), haemoglobin (Hb), fasting cholesterol (CHOL), triglyceride TRIGL), plasma glucose, calcium (Ca), phosphate (PO4), alkaline phosphatase (ALK PHOS), parathyroid hormone (PTH) concentrations, and 24-h urinary protein were assessed in all patients. Seventy-seven per cent were on antihypertensive medication. RESULTS: LVH was detected in 16% of patients with CrCL > 30 ml/min, and 38% of patients with CrCl < 30 ml/min. By stepwise regression analysis, ambulatory systolic BP (P < 0.0001), male gender (P < 0.0001), BMI (P < 0.0002), and Hb concentration (P < 0.002) were the only independent determinants of left ventricular (LV) mass. Nocturnal systolic BP (P < 0.02) was the main determinant of LVH in the group of patients with advanced CRF. The correlation between left ventricular mass index (LVMI) and mean 24-h ambulatory systolic BP (r = 0.52, 95% confidence interval 0.50-0.54) was statistically significantly stronger than with outpatient systolic BP (r = 0.25, 95% confidence interval 0.23-0.27). The same was true for the correlation between LVMI and mean 24-h ambulatory diastolic BP (r = 0.42, 95% confidence interval 0.40-0.44), and outpatient diastolic BP (r = 0.22, 95% confidence interval 0.20-0.24). CONCLUSIONS: Twenty-four hour ambulatory BP recording and echocardiography are required for accurate diagnosis of inadequate BP control and early LVH in patients with chronic renal impairment, independent determinants of which are hypertension, male sex, BMI, and anaemia.

Adult↗
PubMed1997

Expression of aquaporin-1 (AQP1) in the adult and developing sheep kidney.

The distributions of aquaporin-1 mRNA and protein were studied by hybridization histochemistry with a homologous riboprobe and immunohistochemistry, in the adult sheep kidney. Heaviest labelling occurred in the thin descending limb (DTL) of the loop of Henle in the inner stripe of the outer medulla, with apparent decreasing expression in the inner medulla, outer stripe of the outer medulla and cortex, but no quantitation was performed. Only proximal tubules (PT) (convoluted and straight) and DTL labelled. The glomerulus showed no labelling, consistent with the pattern in the rat but different to that in the human. During ontogeny, no labelling occurred in the mesonephros at 27 or 41 days of gestation (term = 145-150 days) but other structures did label at 27 days (heart, lung bud, blood vessels surrounding developing spinal cord). Labelling first occurred faintly in the metanephros at 41 days of gestation and increased throughout gestation consistent with morphological development of nephrons.

Age Factors↗
PubMed1996

Differential release of prostaglandins by organ cultures of human fetal trachea and lung.

Human fetal lung at 16-19 weeks gestation has a partially differentiated epithelium, and in organ culture, distal airsacs dilate and the epithelium autodifferentiates to type I and II pneumatocytes, processes regulated by endogenous prostaglandin PGE2. Human fetal trachea, at the same gestation, has a terminally differentiated mucociliary epithelium but after 4-6 d in organ culture, develops squamous metaplasia. Tracheal cultures restricted to 3 d have normal phase-contrast and light microscopy appearances and immunohistochemical reactivities (epithelium: cytokeratin 7,8,18; glutathione S-transferase pi-isozyme; epithelial membrane antigen and mesenchyme; desmin; vimentin). In human fetal trachea organ cultures, the predominant prostaglandins released are 6-keto-PGF1 alpha, PGF2 alpha, and PGE2, a pattern similar to that previously described for human adult trachea and lung. In fetal lung cultures, 13,14-dihydro-15-keto-PGF2 alpha is the major prostaglandin released with lesser amounts of 13,14-dihydro-15-keto-PFG2 alpha,PGF2 alpha,PGE2, and 6-keto-PGF1 alpha. Human fetal lung in vitro has the competence to self-differentiate, as early as 12 weeks gestation and presence of high levels in fetal lung of the inactive metabolite 13,14-dihydro-15-keto-PGE2 relative to PGE2 suggests that active prostaglandin catabolism may be one of the mechanisms to retard this stage of maturation in vivo by limiting PGE2 availability. Surprisingly, the profile of prostaglandins released from fetal lung organ culture does not change to that of a mature lung with terminal differentiation of the epithelium, and this may indicate differences in the expression of key prostaglandin-metabolizing enzymes in developing human fetal lung in culture and with in utero ontogeny.

Animals↗
PubMed1996

Detection of Cryptosporidium parvum oocysts in faeces: comparison of conventional coproscopical methods and the polymerase chain reaction.

Conventional and coproscopical methods were compared with the polymerase chain reaction (PCR) for the detection of Cryptosporidium oocysts in bovine faeces. Oocysts were not detected in samples seeded with 10,000 oocysts following formol ether sedimentation and examination using auramine phenol (AP) or by immunofluorescent (IF) staining. When oocysts were concentrated using sucrose flotation the threshold of detection was 4000 oocysts per gram for both staining methods. Following salt flotation 4000 oocysts per gram could be reliably detected by AP staining but the detection limit was increased to 6000 oocysts per gram using IF staining. The recovery of oocysts was significantly less than expected for all techniques. A specific PCR coupled with immunomagnetic particle separation (IMS) of samples detected five oocysts per ml of diluted faeces, which corresponds to 80-90 oocysts per gram. Even allowing for the dilution of formed faecal samples, required for IMS, this represents an increase in sensitivity of several orders of magnitude over the conventional corpodiagnostic methods.

Animals↗
PubMed1996

Problems in assessing the audiogram in patients with severe hearing impairment.

Severe hearing impairment (SHI) is an impairment of hearing in which the air conduction mean over 0.5-4 kHz in the better hearing ear lies between 70 and 90 dB. Masking of bone and air conduction thresholds is seldom possible with SHI, leading to difficulties in assessing the pure tone audiogram whenever there is a potential air bone gap in either ear. An audiological survey of 83 patients with severe hearing impairment was conducted. In 16 per cent of patients there was no possibility of a material air bone gap in either ear and no difficulty in interpreting the audiogram. In 23 (28 per cent), the audiogram was consistent with, but did not prove the presence of, an air bone gap in the poorer hearing ear. In 25 patients (30 per cent of 108) the better hearing ear could not be determined, and in 22 (27 per cent) a profound sensorineural impairment in the poorer hearing ear could not be excluded. The implications of this for the otologist are discussed.

Adult↗
PubMed1995

The results of two years operation of the visiting specialist service to the Waikato mobile ear clinic.

AIM: To review the function and results of the Health Waikato mobile ear clinic service 1993-4. METHOD: Data were collected on all children reviewed at the fortnightly specialist clinics conducted in the mobile ear clinics during 1993-4. An overall pathological assessment of the middle ear and eardrum was made for each ear. RESULTS: Of the 467 children examined 311 children were wait listed for elective surgery. Pathology ranged from recurrent acute otitis media to cholesteatoma. Large numbers of children were found with atelectasis of the tympanic membrane. Children as young as seven years of age required modified radical mastoidectomy for treatment of otorrhea due to cholesteatoma. CONCLUSIONS: The results of this survey show the mobile ear clinic service requires a large amount of resources to operate. The mobile ear clinic generates a large operative workload which creates an imbalance between resources devoted to finding the disease and those devoted to treating it. Recommendations include a tighter integration between the mobile ear clinic and the hospital, and appropriate allocation of treatment services to treat the children identified by the service.

Acute Disease↗
PubMed1995

A misdiagnosis of X-linked adrenoleukodystrophy in cultured chorionic villus cells by the measurement of very long chain fatty acids.

A case is reported of a male fetus at risk of X-linked adrenoleucodystrophy who showed a normal cultured chorionic villus cell very long chain fatty acid (VLCFA) profile but at birth exhibited grossly abnormal plasma and cultured fibroblast VLCFAs. Maternal contamination or a sample mix-up was excluded by chromosome analysis and analysis of polymorphic markers. This is the second report of a fetus affected with this disorder who showed normal cultured chorionic villus cell VLCFAs. It highlights the importance of a proper audit of all prenatal diagnoses to evaluate method reliability.

Adrenoleukodystrophy↗
PubMed1995

Blood donation and Ajzen's theory of planned behaviour: an examination of perceived behavioural control.

In spite of the success achieved by the theory of reasoned action, researchers continue to suggest that new components should be added to the original model. Indeed, Ajzen has himself acknowledged that some behaviours may be subject to control problems and thus proposed the theory of planned behaviour to handle behaviours of this kind. This study set out to explore the predictive superiority of the revised theory of planned behaviour by focusing on blood donation, a behavioural domain in which volitional control was thought to be incomplete. It was also the intention to explore the extent to which the belief-based measure of attitude exists as a multidimensional construct. An Ajzen & Fishbein type questionnaire was administered to 141 undergraduate students. Multiple regression analyses provided strong support for the theory of planned behaviour, suggesting that perception of control has an important impact on a person's behavioural motivation. Also, some support for a multidimensional representation of the belief-based measure of attitude was provided.

Adult↗
PubMed1994

Clinical validation of a radionuclide detector to measure ejection fraction in critically ill patients.

The use of a new non-imaging nuclear probe (Cardioscint) capable of continuous online monitoring of left ventricular function is described in critically ill patients undergoing mechanical ventilation. Ejection fraction, measured by the Cardioscint, was compared with that measured by echocardiography. The mean difference was -1.1% (95% confidence interval -2.9 to +0.6%). Mean difference +/- 2 SD was +10.6 to -12.8% (95% confidence intervals +7.5 to 13.6% and -15.8 to -9.0%, respectively). Examples of fluid loading and inotropic support showed comparable changes in stroke counts measured by the Cardioscint and stroke index measured by thermodilution. The Cardioscint is a practical bedside method for continuous or repeated measurement of ejection fraction and for assessing the response to therapeutic interventions in critically ill patients.

Adult↗
PubMed1993

Detection of Cryptosporidium parvum using a specific polymerase chain reaction.

The design and use of polymerase chain reaction primers and probes as reagents for the detection of Cryptosporidium parvum are described. Sensitive and specific amplification of a 329 base pair product was demonstrated by ethidium bromide staining and hybridisation of radiolabelled probes. These reagents have the potential for application to diagnostic samples, environmental monitoring and epidemiological surveys.

Animals↗