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Biomedical subjects

G MacGregor

Publications and source records attributed to G MacGregor.

At least 19 recordsLinked to original sources
PubMed2005

Breath condensate ammonium is lower in children with chronic asthma.

Exhaled breath condensate pH and ammonium reflect asthmatic status and acute exacerbations in adults. The aim of this study was to assess whether pH and ammonium could reflect asthma and its severity in children. The current study comprised two parts: 1) a cross-section of 74 children with asthma (median age 10.5 yrs) compared with 47 healthy controls (median age 10 yrs); and 2) longitudinal assessment of eight children (mean age 8.5 yrs) admitted with asthma exacerbation. Condensate pH and ammonium were compared with clinical observations. In the cross-sectional part of the study, lower per cent forced expiratory volume in one second was associated with more symptoms and treatment. There was no significant difference between median pH in children with stable asthma (6.05) compared with controls (5.90). Ammonium was significantly lower in children with asthma (median 258 microM) compared with controls (median 428 microM). No association was found between ammonium or pH and lung function or symptom-free days. In the longitudinal study, significant improvements in oxygen saturation and respiratory rate with treatment of an acute exacerbation were not reflected by changes in pH or ammonium. In conclusion, pH does not appear to reflect disease or severity in children with asthma. Ammonium was significantly lower in children with asthma when compared with controls.

Adolescent↗
PubMed2002

Airways in cystic fibrosis are acidified: detection by exhaled breath condensate.

BACKGROUND: The loss of cystic fibrosis transmembrane conductance regulator (CFTR) mediated chloride conductance does not fully explain the diverse pathologies evident in patients with cystic fibrosis (CF). Bicarbonate (HCO(3)(-)) secretion is also impaired in CFTR expressing tissues and CFTR is thought to regulate HCO(3)(-) secretion at the apical membrane of epithelial cells. We hypothesised that the epithelial lining fluid (ELF) of patients with CF would be acidified and that this may be worsened during an infective exacerbation due to the increased inflammatory burden. METHODS: pH and nitrite levels in exhaled breath condensate (EBC) from 12 healthy non-smoking controls and 30 patients with CF (11 of whom were in an infective exacerbation) were measured. A further nine patients were studied before and after intravenous antibiotic treatment for an exacerbation of CF. RESULTS: The pH of EBC was significantly lower in patients with stable CF than in controls (5.88 (0.32) v 6.15 (0.16), p=0.017), and was further reduced in CF patients with an exacerbation (5.32 (0.38), p=0.001) compared with stable CF patients. EBC pH increased significantly following antibiotic treatment from 5.27 (0.42) to 5.71 (0.42), p=0.049). Nitrite levels in EBC were increased in CF patients with an exacerbation compared with control subjects (4.4 (4.0) micro m v 1.6 (1.6) micro m p=0.047). No correlation was found between EBC pH and nitrite levels. CONCLUSIONS: These findings support the hypothesis that airway acidification occurs in CF. This acidity is in part a function of inflammation as the pH of the EBC of patients increased significantly with treatment of an exacerbation, although not to control levels. Acidic pH of the ELF may play a role in the pathophysiology of CF lung disease and requires further investigation.

Adult↗
PubMed2000

Early discharge for patients with exacerbations of chronic obstructive pulmonary disease: a randomized controlled trial.

BACKGROUND: We have previously reported the use of a hospital based respiratory nurse service (Acute Respiratory Assessment Service, ARAS) to support home treatment of patients with exacerbations of chronic obstructive pulmonary disease (COPD). A controlled trial was undertaken to compare early discharge with home treatment supported by respiratory nurses with conventional hospital management of patients admitted with exacerbations of COPD. METHODS: Patients with COPD admitted as emergencies were identified the next working day. They were eligible for inclusion in the study if the differential diagnosis included an exacerbation of COPD, but were excluded if other medical conditions or acidotic respiratory failure required inpatient investigation or management. Of 360 patients reviewed, 209 were being assessed for other active medical problems and were excluded, 33 potential participants were already involved in research studies and so were ineligible, and 37 did not wish to participate in the study. Eighty one patients were randomised to receive conventional inpatient care (n=40) or to planned early discharge the next working day (n=41). Those discharged early continued treatment at home under the supervision of specialist respiratory nurses. Outcome measures were readmission, additional hospital days, and deaths within 60 days of initial admission. Process measures included number of visits, duration of follow up by the respiratory nurse, and additional treatment provided to support early discharge. RESULTS: On an intention to treat basis, a policy of early discharge reduced inpatient stay from a mean of 6.1 (range 1-13) days with conventional management to 3.2 (1-16) days with an early discharge policy. Twelve patients (30% conventional management, 29.3% early discharge) were readmitted in each group giving a mean difference in readmission of 0.7% (95% CI of the difference -19.2 to 20.6). In the conventional management group readmitted patients spent a mean of 8.75 additional days in hospital compared with 7.83 days in the early discharge group, giving a mean difference of 0.92 days (95% CI of the difference -6.5 to 8.3). There were two deaths (5%) in the conventional management group and one (2.4%) in the early discharge group, a mean difference of 2.6% (95% CI of the difference -5.7 to 10.8). CONCLUSIONS: Patients with acute exacerbations of COPD uncomplicated by acidotic respiratory failure or other medical problems can be discharged home earlier than is current practice with support by visiting respiratory nurses. No difference was found in the subsequent need for readmission.

Aged↗
PubMed1999

Guidelines for management of hypertension: report of the third working party of the British Hypertension Society.

Use non-pharmacological measures in all hypertensive and borderline hypertensive people. Initiate antihypertensive drug therapy in people with sustained systolic blood pressures (BP) >/=160 mm Hg or sustained diastolic BP >/=100 mm Hg. Decide on treatment in people with sustained systolic BP between 140 and 159 mm Hg or sustained diastolic BP between 90 and 99 mm Hg according to the presence or absence of target organ damage, cardiovascular disease or a 10-year coronary heart disease (CHD) risk of >/=15% according to the Joint British Societies CHD risk assessment programme/risk chart. In people with diabetes mellitus, initiate antihypertensive drug therapy if systolic BP is sustained >/=140 mm Hg or diastolic BP is sustained >/=90 mm Hg. In non-diabetic hypertensive people, optimal BP treatment targets are: systolic BP <140 mm Hg and diastolic BP <85 mm Hg. The minimum acceptable level of control (Audit Standard) recommended is <150/<90 mm Hg. Despite best practice, these levels will be difficult to achieve in some hypertensive people. In diabetic hypertensive people, optimal BP targets are; systolic BP <140 mm Hg and diastolic BP <80 mm Hg. The minimum acceptable level of control (Audit Standard) recommended is <140/<90 mm Hg. Despite best practice, these levels will be difficult to achieve in some people with diabetes and hypertension. In the absence of contraindications or compelling indications for other antihypertensive agents, low dose thiazide diuretics or beta-blockers are preferred as first-line therapy for the majority of hypertensive people. In the absence of compelling indications for beta-blockade, diuretics or long acting dihydropyridine calcium antagonists are preferred to beta-blockers in older subjects. Compelling indications and contraindications for all antihypertensive drug classes are specified. For most hypertensives, a combination of antihypertensive drugs will be required to achieve the recommended targets for blood pressure control. Other drugs that reduce cardiovascular risk must also be considered. These include aspirin for secondary prevention of cardiovascular disease, and primary prevention in treated hypertensive subjects over the age of 50 years who have a 10-year CHD risk >/=15% and in whom blood pressure is controlled to the audit standard. In accordance with existing British recommendations, statin therapy is recommended for hypertensive people with a total cholesterol >/=5 mmol/L and established vascular disease, or 10-year CHD risk >/=30% estimated from the Joint British Societies CHD risk chart. Glycaemic control should also be optimised in diabetic subjects. Specific advice is given on the management of hypertension in specific patient groups, ie, the elderly, ethnic subgroups, diabetes mellitus, chronic renal disease and in women (pregnancy, oral contraceptive use and hormone replacement therapy). Suggestions for the implementation and audit of these guidelines in primary care are provided.

Antihypertensive Agents↗
PubMed1999

Developmental regulation of Bcl-2 family protein expression in the involuting mammary gland.

Epithelial cells within the mammary gland undergo developmental programmes of proliferation and apoptosis during the pregnancy cycle. After weaning, secretory epithelial cells are removed by apoptosis. To determine whether members of the Bcl-2 gene family could be involved in regulating this process, we have examined whether changes in their expression occur during this developmental apoptotic program in vivo. Bax and Bcl-x were evenly expressed throughout development. However, expression of Bak and Bad was increased during late pregnancy and lactation, and the proteins were present during the time of maximal apoptotic involution. Thereafter, their levels declined. In contrast, Bcl-w was expressed in pregnancy and lactation but was downregulated at the onset of apoptosis. Bcl-2 was not detected in lactating or early involuting mammary gland. Thus, the pro-apoptotic proteins Bax, Bak and Bad, as well as the death-suppressors Bcl-x, Bcl-2 and Bcl-w, are synthesised in mouse mammary gland, and dynamic changes in the expression profiles of these proteins occurs during development. To determine if changes in Bak and Bcl-w expression could regulate mammary apoptosis, their effect on cultured mouse mammary epithelial cells was examined in transient transfection assays. Enforced expression of Bak induced rapid mammary apoptosis, which could be suppressed by coexpression of Bcl-w. In extracts of mammary tissue in vivo, Bak heterodimerized with Bcl-x whereas Bax associated with Bcl-w, but Bak/Bcl-w heterodimers were not detected. Thus, Bak and Bcl-w may regulate cell death through independent pathways. These results support a model in which mammary epithelial cells are primed for apoptosis during the transition from pregnancy to lactation by de novo expression of the death effectors Bak and Bad. It is suggested that these proteins are prevented from triggering apoptosis by anti-apoptotic Bcl-2 family proteins until involution, when the levels of Bcl-w decline. Our study provides evidence that regulated changes in the expression of cell death genes may contribute to the developmental control of mammary apoptosis.

Animals↗
PubMed1998

Abnormalities of nasal potential difference measurement in Liddle's syndrome.

In Liddle's syndrome, a rare inherited form of hypertension, epithelial sodium channel mutations appear to cause high blood pressure by increasing sodium reabsorption through sodium channels in the renal distal tubule. This increase in channel activity has not been confirmed previously by in vivo measurement. We have made transnasal potential difference measurements (effective in detection of increased sodium channel activity in cystic fibrosis) in three brothers with genetically proven Liddle's syndrome, their unaffected sister, and 40 normotensive controls. Maximum potential difference after 2 wk off treatment in the affected brothers was -30.4+/-1.2 mV (values mean+/-SD, lumen-negative with respect to submucosa) and was significantly more lumen-negative than that of the control group (-18.6+/-6.8 mV, P = 0.0228) or the unaffected sister (-18.25 mV, P < 0.01). The change in potential difference after topical application of 10(-)4 M amiloride was greater in the Liddle's patients, 14.0+/-2.1 mV, than in controls (7.9+/-3.9 mV, P = 0.0126) or the unaffected sister (5.5 mV, P < 0.05). This is the first in vivo demonstration of increased sodium channel activity in Liddle's syndrome. If these results are confirmed in other kindreds with this condition, then nasal potential difference measurements could provide a simple clinical test for Liddle's syndrome.

Adult↗
PubMed1987

The endogenous cytochemically assayable Na-K-ATPase inhibitor and its relation to hypertension.

Acute volume expansion endows the plasma with the capacity to cause a natriuresis, to inhibit Na-K-ATPase and to stimulate vascular reactivity. These changes are due to a change in the concentration of two or more substances in the plasma. Atrial natriuretic peptides do not inhibit Na-K-ATPase and they decrease vascular reactivity. The search for the Na-K-ATPase inhibitor has been hampered by the lack of specificity of most assays which demonstrate the presence of many irrelevant Na-K-ATPase inhibitors. Cytochemical bioassays, however, appear to have a certain selectivity. They disclose the presence of a Na-K-ATPase inhibitor in the plasma, the concentration of which is controlled by salt intake but the only known substance so far tested, which these bioassays will detect, is ouabain. The hypothalamus contains the highest concentration of the cytochemically bioassayable inhibitory material and its content is also controlled by salt intake. The substance responsible for the cytochemically bioassayable inhibitory activity in the plasma and the hypothalamus share the same physico-chemical properties and on extraction appear in the same fraction. It is possible therefore, that the Na-K-ATPase inhibitor which is detectable by the cytochemical assays in the plasma and hypothalamus is the same. The concentration of cytochemically bioassayable Na-K-ATPase inhibitory activity is raised in the plasma of patients with essential hypertension, the SHR rat and the Milan hypertensive rat, as is the concentration of atrial natriuretic peptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗