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Biomedical subjects

R Darnell

Publications and source records attributed to R Darnell.

15 recordsLinked to original sources
PubMed2004

Effect of ammonium and nitrate on ferric chelate reductase and nitrate reductase in Vaccinium species.

BACKGROUND AND AIMS: Most Vaccinium species have strict soil requirements for optimal growth, requiring low pH, high iron availability and nitrogen primarily in the ammonium form. These soils are limited and are often located near wetlands. Vaccinium arboreum is a wild species adapted to a wide range of soils, including high pH, low iron, and nitrate-containing soils. This broader soil adaptation in V. arboreum may be related to increased efficiency of iron or nitrate uptake compared with the cultivated Vaccinium species. METHODS: Nitrate, ammonium and iron uptake, and nitrate reductase (NR) and ferric chelate reductase (FCR) activities were compared in two Vaccinium species grown hydroponically in either nitrate or ammonia, with or without iron. The species studied were the wild V. arboreum and the cultivated V. corymbosum interspecific hybrid, which exhibits the strict soil requirements of most Vaccinium species. RESULTS: Ammonium uptake was significantly greater than nitrate uptake in both species, while nitrate uptake was greater in the wild species, V. arboreum, compared with the cultivated species, V. corymbosum. The increased nitrate uptake in V. arboreum was correlated with increased root NR activity compared with V. corymbosum. The lower nitrate uptake in V. corymbosum was reflected in decreased plant dry weight in this species compared with V. arboreum. Root FCR activity increased significantly in V. corymbosum grown under iron-deficient conditions, compared with the same species grown under iron-sufficient conditions or with V. arboreum grown under either iron condition. CONCLUSIONS: V. arboreum appears to be more efficient in acquiring nitrate compared with V. corymbosum, possibly due to increased NR activity and this may partially explain the wider soil adaptation of V. arboreum.

Adaptation, Physiological↗
PubMed2002

Prevalence of hypertension in children after early repair of coarctation of the aorta: a cohort study using casual and 24 hour blood pressure measurement.

OBJECTIVE: To study the prevalence of hypertension in a cohort of patients using the current strategy of repair in early childhood. PATIENTS: The cohort of patients with coarctation of the aorta born between 1983 and 1992. INTERVENTION: Casual (mean of three resting readings) and 24 hour blood pressure were measured in 119 children and compared with data from 1034 normal controls. The arch repair and left ventricular parameters were assessed using Doppler echocardiography. RESULTS: Median ages at first intervention and at blood pressure measurement were 0.2 years (interquartile range 0.04-2.0) and 12.0 years (9.0-14.5), respectively. Doppler velocity in the descending aorta was significantly associated with blood pressure (r = 0.28, p = 0.002 for casual systolic blood pressure (SBP); r = 0.26, p = 0.005 for mean 24 hour SBP). Patients were classified as having "no" (n = 70) or "mild" (n = 49) arch obstruction. Casual SBP was > 95th centile in 28% (34 of 119) overall and in 21% (15 of 70) of the no arch obstruction group. Mean 24 hour SBP was > 95th centile in 30% (36 of 119) overall and in 19% (13 of 70) of the no obstruction group. The sensitivity and specificity of casual SBP in detecting increased 24 hour SBP were 66% and 88%, respectively. CONCLUSIONS: This unique study of a large cohort of patients treated for coarctation in early childhood showed that a disappointingly high prevalence of hypertension is already apparent in children aged 7-16 years in the absence of significant arch obstruction, whether assessed by 24 hour or by casual blood pressure measurement.

Adolescent↗
PubMed2001

Children's respiratory health and daily particulate levels in 10 nonurban communities.

We conducted a study to assess the association between the acute respiratory health of children and the levels of particulates in communities near and away from active opencast coal mines. The study enrolled children aged 1-11 years from the general population of five socioeconomically matched pairs of nonurban communities in northern England. Diaries of respiratory events were collected for 1405 children, and information was collected on the consultations of 2442 children with family/general practitioners over the 6-week study periods during 1996-1997, with concurrent monitoring of particulate levels. The associations found between daily PM(10) levels and respiratory symptoms were frequently small and positive and sometimes varied between communities. The magnitude of these associations were in line with those from previous studies, even though daily particulate levels were low, and the children were drawn from the general population, rather than from the population with respiratory problems. The associations among asthma reliever use, consultations with general practitioners, and daily particulate levels were of a similar strength but estimated less precisely. The strength of association between all respiratory health measures and particulate levels was similar in communities near and away from opencast coal mining sites.

Air Pollutants↗
PubMed2001

Consultations of children living near open-cast coal mines.

Because of local concerns, general practitioner consultation rates in children living in communities close to and away from open-cast mines were compared. Information on consultations was collected on 2,442 children 1-11 years of age living in five socioeconomically matched pairs of open-cast and control communities in northern England. The data collection periods were 6 weeks each during 1996-1997 and the 52-week periods preceding these weeks. Consultations were categorized as respiratory, skin and eye conditions (possibly exacerbated by particulate matter), or other conditions. Over the 6-week periods, children in 4/5 pairs of open-cast and control communities had similar consultation rates for all conditions combined [2.7 vs. 2.4 per person-year; odds ratio (OR) = 1.1; 95% confidence interval (CI), 0.96-1.3). Consultations were higher in the open-cast communities for respiratory, skin, and eye conditions (2.1 vs. 1.5 per person-year; OR = 1.4; 95% CI, 1.2-1.7), and respiratory conditions alone (1.5 vs. 1.1 per person-year; OR = 1.5; 95% CI, 1.2-1.8). However, increases in consultation rates in open-cast communities were generally not seen over the portions of the 52-week periods when the open-cast sites were either active or inactive.

Air Pollution↗
PubMed2000

Living near opencast coal mining sites and children's respiratory health.

OBJECTIVES: To answer the question whether living near opencast coal mining sites affects acute and chronic respiratory health. METHODS: All 4860 children aged 1-11 from five socioeconomically matched pairs of communities close to active opencast sites and control sites away from them were selected. Exposure was assessed by concentrations of particulate matter with aerodynamic diameter < 10 microns (PM10), residential proximity to active opencast sites, and particle composition. PM10 was monitored and sampled for 6 weeks in four pairs, and for 24 weeks in one pair. A postal questionnaire collected data on health and lifestyle. Daily health information was collected by a symptom diary (concurrently with PM10 monitoring) and general practitioner (GP) records were abstracted (concurrently with PM10 monitoring and 52 weeks before the study). Outcomes were the cumulative and period prevalence (2 and 12 months) of wheeze, asthma, bronchitis, and other respiratory symptoms, and the prevalence and incidence of daily symptoms and GP consultations. RESULTS: Patterns of the daily variation of PM10 were similar in opencast and control communities, but PM10 was higher in opencast areas (mean ratio 1.14, 95% confidence interval (95% CI) 1.13 to 1.16, geometric mean 17.0 micrograms/m3 v 14.9 micrograms/m3). Opencast sites were a measurable contributor to PM10 in adjacent areas. Little evidence was found for associations between living near an opencast site and an increased prevalence of respiratory illnesses, asthma severity, or daily diary symptoms, but children in opencast communities 1-4 had significantly more respiratory consultations (1.5 v 1.1 per person-year) than children in control communities for the 6 week study periods. Associations between daily PM10 concentrations and acute health events were similar in opencast and control communities. CONCLUSIONS: Children in opencast communities were exposed to a small but significant amount of additional PM10 to which the opencast sites were a measurable contributor. Past and present respiratory health of children was similar, but GP consultations for respiratory conditions were higher in opencast communities during the core study period.

Acute Disease↗
PubMed1997

Anatomic localization of alternatively spliced leptin receptors (Ob-R) in mouse brain and other tissues.

Leptin's effects are mediated by interactions with a receptor that is alternatively spliced, resulting in at least five different murine forms: Ob-Ra, Ob-Rb, Ob-Rc, Ob-Rd, and Ob-Re. A mutation in one splice form, Ob-Rb, results in obesity in mice. Northern blots, RNase protection assays, and PCR indicate that Ob-Rb is expressed at a relatively high level in hypothalamus and low level in several other tissues. Ob-Ra is expressed ubiquitously, whereas Ob-Rc, -Rd, and -Re RNAs are only detectable using PCR. In hypothalamus, Ob-Rb is present in the arcuate, ventromedial, dorsomedial, and lateral hypothalamic nuclei but is not detectable in other brain regions. These nuclei are known to regulate food intake and body weight. The level of Ob-Rb in hypothalamus is reduced in mice rendered obese by gold thioglucose (GTG), which causes hypothalamic lesions. The obesity in GTG-treated mice is likely to be caused by ablation of Ob-Rb-expressing neurons, which results in leptin resistance.

Alternative Splicing↗
PubMed1997

Can an antihistamine delay appearance of hay fever symptoms when given prior to pollen season?

Mizolastine is a new, nonsedating antihistamine providing satisfactory symptom relief in allergic conditions. The purpose of this study was to determine whether the onset of hay fever symptoms could be delayed in patients known to suffer seasonal allergic rhinoconjunctivitis symptoms if mizolastine was given before the pollen season. This double-blind study involved 342 patients, randomly allocated to once-daily 10 mg mizolastine (n = 115), once-daily 120 mg terfenadine (n = 116), or placebo (n = 111) groups. All patients started treatment on 1 May, before the onset of the grass pollen season. The prophylactic effect of test drugs was assessed on their ability to delay the time to the first hay fever crisis of the season, which was defined by the occurrence of one of the following events: use of rescue medication, study withdrawal because of treatment failure, or total diary symptom score over 18. Active treatments prolonged the time to the first crisis by approximately 1 week (mizolastine 55 days, terfenadine 57 days) in comparison with placebo (50 days) (survival curve analysis: Logrank test, P = 0.01; Wilcoxon test, P = 0.03). Tolerability was satisfactory and comparable between groups. Thus, mizolastine can be safely used to delay and to treat symptoms of seasonal allergic rhinitis.

Adult↗
PubMed1996

Once daily mometasone furoate aqueous nasal spray is as effective as twice daily beclomethasone dipropionate for treating perennial allergic rhinitis patients.

BACKGROUND: Perennial allergic rhinitis is chronic and persistent, may lead to a constellation of secondary complaints including sinusitis, mouth-breathing, and some symptoms resembling a permanent cold, and often requires constant medical intervention. Well-tolerated nasal corticosteroids, alone or in combination with antihistamines, have been found to be very effective in treating this condition. OBJECTIVE: To compare the effectiveness and tolerability of mometasone furoate aqueous suspension, a new once daily nasal spray, to placebo vehicle and to beclomethasone dipropionate, administered twice daily, in patients with perennial allergic rhinitis. METHODS: This was a randomized, double-blind, placebo-controlled, double-dummy, parallel group study, in 427 patients age 12 years and older at 24 centers in Canada and Europe. Patients allergic to at least one perennial allergen, confirmed by medical history, skin testing, and adequate symptomatology were eligible to receive one of the following regimens for 3 months: mometasone furoate, 200 micrograms only daily; beclomethasone dipropionate, 200 micrograms twice daily (400 micrograms total dose); or placebo vehicle control. The primary efficacy variable was the change from baseline in total AM plus PM diary nasal symptom score over the first 15 days of treatment. RESULTS: Three hundred eighty-seven patients were valid for efficacy. For the primary efficacy variable, mometasone furoate was significantly (P < or = .01) more effective than placebo and was indistinguishable from beclomethasone dipropionate. Similar trends were seen among individual symptoms, physician symptom evaluations, and therapeutic response. There was no evidence of tachyphylaxis. All treatments were well tolerated. CONCLUSIONS: Mometasone furoate nasal spray adequately controls symptoms of perennial allergic rhinitis, offers the advantage of once daily treatment, and is well tolerated.

Administration, Intranasal↗
PubMed1994

A double-blind comparison of fluticasone propionate aqueous nasal spray, terfenadine tablets and placebo in the treatment of patients with seasonal allergic rhinitis to grass pollen.

Fluticasone Propionate Aqueous Nasal Spray (FPANS) contains a topically active glucocorticoid fluticasone propionate which has been used successfully for the treatment of seasonal allergic rhinitis. This multicentre, randomized, double-blind, double-dummy, placebo-controlled, parallel group study was designed to compare the efficacy and tolerability of FPANS with terfenadine tablets or placebo in controlling the symptoms of allergic rhinitis to grass pollen. Two hundred and fourteen patients were treated for 6 weeks during the grass pollen season with either FPANS 200 micrograms once daily, terfenadine tablets (60 mg) twice daily or placebo. Efficacy was evaluated by the analysis of symptom-free days and median symptom scores. Patients receiving FPANS had significantly more days free of nasal blockage on waking (P = 0.012) and during the day (P = 0.01) and of rhinorrhoea (P = 0.027) than those receiving terfenadine. Additionally, in terms of absolute efficacy, patients receiving FPANS demonstrated significantly more days free of the above symptoms (P = 0.017, P = 0.028, P = 0.004, respectively) and of sneezing (P < 0.001) than those receiving placebo. There were no significant differences in symptoms of nasal itching, eye symptoms, of symptoms of drowsiness between the three treatment groups. Patients in the FPANS group had significantly lower median symptom scores for nasal blockage on waking (P < 0.001) and during the day (P < 0.018) than those in the terfenadine group and significantly lower scores for nasal blockage on waking (P < 0.001), sneezing (P < 0.013) and rhinorrhoea (P = 0.005) than those in the placebo group.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1983

Milk-borne campylobacter enteritis in a rural area.

During November and December 1981 more than 50 residents in a village in Derbyshire had an acute gastrointestinal illness. One month later a second outbreak occurred affecting another 22 people. Campylobacter jejuni was isolated from 12 patients; no other gastrointestinal pathogens were identified. A case-control study showed an association with the consumption of unpasteurized milk from one particular farm. No new cases were identified for 6 months following the application of a Pasteurization Order from 26 January to 23 February 1982.

Adolescent↗
PubMed1977

A procedure for facilitating physical therapy research.

A procedure for facilitating research by physical therapists in a multidimensional practice setting is presented. The article addresses the need for physical therapists to be aware of research opportunities, and provides them with a means for action when such opportunities occur. The developmental sequence of events is described starting with conceptualization and moving through current utilization of the procedure.

Male↗
PubMed1975

Infantile gastroenteritis: a clinical study of reovirus-like agent infection.

In a clinical study of 32 infants with symptoms from infections with the human reovirus-like agent (R.I.A.) identified by electron microscopy (E.M.) of faecal extracts, a fairly consistent clinical pattern was found in 30 who had a gastroenteritis-like illness. The disease was usually mild, affecting mainly infants less than 2 years and males more commonly than females. The incubation period appeared to be 48-72 hours; and the onset was sudden, often with vomiting in the first 1-2 days of the illness. Loose yellow-green offensive stools without blood or mucus developed after a variable time, and there was often accompanying fever. Severe dehydration and electrolyte inbalance were uncommon; and with standard treatment the illness was uncomplicated, usually lasting 5-8 days. These features resemble those of previously reported winter epidemics of infantile non-bacterial gastroenteritis, and it is suggested that these epidemics were due to R.L.A. 2 infants in whom R.L.A. was identified in the stool did not have a gastroenteritis-like illness although both had protracted diarrhoea.

Age Factors↗