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Biomedical subjects

S McKenzie

Publications and source records attributed to S McKenzie.

At least 19 recordsLinked to original sources
PubMed2005

Faecal corticosteroid levels as an indicator of well-being in the tammar wallaby, Macropus eugenii.

Faecal corticosteroid levels were measured in five female tammar wallabies, Macropus eugenii, at Macquarie University, NSW, Australia, to assess their reliability as indicators of well-being in this species. Animals were challenged with a change in conditions over the course of approximately 1 week, comprising movement from group yards to isolation in individual yards, in order to impose a disturbance to homeostasis ("stress"). Faecal samples were collected in 24-h intervals during the study period and analysed for corticosteroid concentration. The use of enzyme immunoassay for the measurement of corticosteroids in marsupial faecal pellets was validated. We observed a significant increase in faecal corticosteroids upon isolation and movement. Faecal corticosteroids remained above initial levels in all five animals throughout the study period, suggesting that faecal corticosteroid concentrations may be a useful indicator of a change in animal well-being. Faecal corticosteroid levels did not correlate with serum cortisol levels, implying that the use of noninvasive methods in a representative marsupial, the tammar wallaby, has the potential to provide information that is not readily apparent using blood-based protocols. Faecal corticosteroid analysis therefore has the potential for application in monitoring the well-being of captive and managed marsupial populations, as part of an integrated system of measures of animal health and well-being.

Adrenal Cortex Hormones↗
PubMed2004

Are serum cortisol levels a reliable indicator of wellbeing in the tammar wallaby, Macropus eugenii?

Serum corticosteroid levels were measured in six female tammar wallabies (Macropus eugenii) at Macquarie University, NSW, Australia, to assess their reliability as indicators of wellbeing in this species. Animals were challenged with a change in conditions over the course of approximately 3 weeks, comprising (i) isolation and movement; (ii) altered feeding routine, in order to impose a disturbance to homeostasis ("stress"). Blood samples were collected five times during the study period, and analysed for corticosteroid concentration and a number of haematological and biochemical measures. The use of enzyme immunoassay for the measurement of corticosteroids in marsupial serum was validated. We found that there was no significant change in serum corticosteroid concentrations in response to either of the changed conditions suggesting that serum corticosteroid concentrations are not reflective of a change in wellbeing. Cortisol was the dominant serum corticosteroid, with concentrations up to 50 times higher than corticosterone. Significant differences were observed in aspartate amino-transferase, alanine amino-transferase, haemoglobin, total erythrocyte count and mean corpuscular haemoglobin concentration over the period of study. However, no significant correlations emerged to justify any of these measures, or serum corticosteroid levels, as reliable indicators of compromised wellbeing in the tammar wallaby.

Animals↗
PubMed2003

Dornase alfa in the treatment of cystic fibrosis in Europe: a report from the Epidemiologic Registry of Cystic Fibrosis.

Dornase alfa (Pulmozyme) treatment for patients with cystic fibrosis (CF) has been shown to improve pulmonary function and reduce exacerbations of infection in a number of placebo-controlled double-blind studies. Data in the Epidemiologic Registry of Cystic Fibrosis (ERCF) in November 1998 were used to assess the long-term effectiveness in routine clinical practice of dornase alfa in terms of pulmonary function and frequency of acute pulmonary exacerbations in CF. At that time, the ERCF contained data on 13,684 CF patients, with a mean observation period of 2.3 years. To be included in the analysis, patients had to have 2 years of data in the Registry in appropriate detail. Overall, untreated patients showed a decline in forced expiratory volume in 1 sec over a 2-year period of -2.3% predicted, but treated patients were stable, showing a change of 0.3% predicted, i.e., a treatment benefit of 2.5%. Compared to untreated patients, there were 25 fewer exacerbations per 100 treated patients per year. The analysis suggested that younger patients were likely to benefit more from treatment. The findings of randomized clinical trials were supported by the data collected in routine clinical practice.

Adolescent↗
PubMed2002

Dynamics of hematopoiesis in paroxysmal nocturnal hemoglobinuria (PNH): no evidence for intrinsic growth advantage of PNH clones.

PNH is characterized by expansion of one or more stem cell clones with a PIG-A mutation, which causes a severe deficiency in the expression of glycosylphosphatidylinositol (GPI)-anchored proteins. There is evidence that the expansion of PIG-A mutant clones is concomitant with negative selection against PIG-A wild-type stem cells by an aplastic marrow environment. We studied 36 patients longitudinally by serial flow cytometry, and we determined the proportion of PNH red cells and granulocytes over a period of 1-6 years. We observed expansion of the PNH blood cell population(s) (at a rate of over 5% per year) in 12 out of 36 patients; in all other patients the PNH cell population either regressed or remained stable. The dynamics of the PNH cell population could not be predicted by clinical or hematologic parameters at presentation. These data indicate that in most cases the PNH cell expansion has already run its course by the time of diagnosis. In addition, since in most cases no further expansion takes place, we can infer that the tendency to overgrow normal cells is not an intrinsic property of the PNH clone.

Adolescent↗
PubMed2001

Understanding childhood asthma in focus groups: perspectives from mothers of different ethnic backgrounds.

BACKGROUND: Diagnosing childhood asthma is dependent upon parental symptom reporting but there are problems in the use of words and terms. The purpose of this study was to describe and compare understandings of childhood 'asthma' by mothers from three different ethnic backgrounds who have no personal experience of diagnosing asthma. A better understanding of parents' perceptions of an illness by clinicians should improve communication and management of the illness. METHOD: Sixty-six mothers living in east London describing their ethnic backgrounds as Bangladeshi, white English and black Caribbean were recruited to 9 focus groups. Discussion was semi-structured. Three sessions were conducted with each ethnic group. Mothers were shown a video clip of a boy with audible wheeze and cough and then addressed 6 questions. Sessions were recorded and transcribed verbatim. Responses were compared within and between ethnic groups. RESULTS: Each session, and ethnic group overall, developed a particular orientation to the discussion. Some mothers described the problem using single signs, while others imitated the sound or made comparisons to other illnesses. Hereditary factors were recognised by some, although all groups were concerned with environmental triggers. Responses about what to do included 'normal illness' strategies, use of health services and calls for complementary treatment. All groups were concerned about using medication every day. Expectations about the quality of life were varied, with recognition that restrictions may be based on parental beliefs about asthma, rather than asthma itself. CONCLUSION: Information from these focus groups suggests mothers know a great deal about childhood asthma even though they have no personal experience of it. Knowledge of how mothers from these ethnic backgrounds perceive asthma may facilitate doctor - patient communication with parents of children experiencing breathing difficulties.

Adult↗
PubMed2001

European Epidemiologic Registry of Cystic Fibrosis (ERCF): comparison of major disease manifestations between patients with different classes of mutations.

SUMMARY. By August 1997, 11,749 patients with cystic fibrosis had been enrolled in the European Epidemiologic Registry of Cystic Fibrosis (ERCF). Genotype analysis had been performed on 8,963 (76%) of these patients, and the majority had one or two identifiable mutations. Patients with known mutations were classified according to the type of mutation (Classes I-V), and were grouped according to the class of mutation on both chromosomes. This resulted in six subgroups, including all patients homozygous for Class I (I/I, n = 72), for Class II (II/II, n = 5,020), and for Class III mutations, (III/III, n = 23). Since there were only 23 patients homozygous for Class III mutations, a fourth group was made up of patients who were compound heterozygous for a Class II and III mutation (II/III, n = 265). There were only five patients homozygous for Class IV mutations, and consequently a fifth group was made up of all patients carrying at least one Class IV mutation, regardless of the nature of the mutation on the other chromosome (IV/any, n = 187). None were homozygous for Class V mutations; consequently, a sixth group consisted of patients carrying at least one Class V mutation (V/any, n = 22). Mean age was highest in groups III/III, IV/any, and V/any (15.6, 16, and 17 years, respectively) as opposed to 12.4 years in group II/II and 13.4 in group II/III, but both group III/III and V/any were small, and the confidence interval of the mean was large. The percentage of patients receiving pancreatic enzymes was lower in groups IV/any and V/any than in any of the other groups, i.e., approximately 50% of patients 18 years or older in both groups as opposed to between 90-100% of all other patients regardless of age. The prevalence of diabetes mellitus increased with age from 2.6% in patients < 18 years to 22.1% in patients 18 years or older in the large group II/II, but was only 1.5% in patients 18 years or older in group IV/any. Disregarding the small group III/III, abnormally elevated liver enzymes and/or bilirubin (1.5 x upper normal limit) was much less frequent in group IV/any than in any of the other groups, both overall and in patients aged 18 years or more. The course of lung disease appeared to be less dependent on genotype than pancreatic function, with only minor differences between groups; however, the mean values of both FVC % and FEV(1) % were slightly higher in group IV/any than all other groups in both younger and older patients. The same was found for the prevalence of some major clinical signs of severe lung disease, such as clubbing, hyperinflation, and crepitations. Overall mean weight expressed as an age percentile was markedly higher in group IV/any than in any other group, which may be related to the finding of a much lower prevalence of chronic P. aeruginosa infection in patients 18 years or older belonging to group IV/any (and V/any) than in any other group. In conclusion, the presence of a class IV mutation appears to offer some degree of protection against pancreatic insufficiency, diabetes mellitus, and liver disease. We confirmed that lung disease follows a milder clinical course in patients with a class IV mutation and that the presence of a class IV mutation (and possibly class V) is associated with a delay in the onset of P. aeruginosa infection.

Adolescent↗
PubMed2001

Swallowing in myotonic muscular dystrophy: a videofluoroscopic study.

OBJECTIVES: (1) To determine how swallow function in patients with myotonic muscular dystrophy (MD) differs from that of healthy controls, (2) to identify the contributors to and predictors of improvement, and (3) to evaluate strategies that facilitate swallowing. DESIGN: Observational. SETTING: University medical center. PARTICIPANTS: Eighteen adults with myotonic MD (age range, 24-58 yr) and 60 healthy adult control subjects (age range, 18-73 yr). INTERVENTIONS: Swallow facilitation strategies. MAIN OUTCOME MEASURES: Between-group comparisons of mean bolus transit times, onsets of swallow gestures, and displacement measures obtained by dynamic lateral view videofluoroscopy. RESULTS: The MD patients' bolus transit times were significantly longer, and onsets of some swallow gestures were significantly delayed. Upper esophageal sphincter opening was prolonged (myotonic MD,.61 +/-.13s; control,.5 +/-.11s). Hyoid displacement was significantly less in men with myotonic MD (1.9 +/-.05 cm) than in male controls (2.4 +/-.68 cm); this difference was not observed between control and myotonic women. Of particular importance was the markedly reduced pharyngeal constriction found in the MD group. CONCLUSIONS: Weakness associated with the disease, as opposed to myotonia, was the most significant contributor to impairment. Persons at risk for aspiration may be identified by a measure of pharyngeal area. Selected strategies to facilitate pharyngeal clearing are worthwhile.

Adult↗
PubMed2001

Short-term 17-beta-estradiol administration does not affect metabolism in young males.

We have previously demonstrated that females oxidize more lipid and less protein and carbohydrate during endurance exercise [21]. Several studies in male rats have demonstrated similar metabolic changes after 4 d of 17-beta-estradiol (E2) administration. Our purpose was to study the effects of E2 administration upon substrate metabolism during 90min of cycle ergometry at 60% VO2peak in 11 healthy, young males. E2 was administered in a single-blind, cross-over, randomized fashion for 11 d (100 microg.d(-1) x 3.5d --> 200 microg.d(-1) x 3.5 d --> 300 microg.d(-1) x 4.0 d). Respiratory exchange ratio (RER), VO2, Ve, HR, lactate, and glucose were measured every 30 min during exercise and E2, testosterone TEST, glycerol and triglycerides were measured prior to exercise T = 0 min. Muscle biopsies were taken from the vastus lateralis before and after exercise for glycogen determination. Estradiol treatment resulted in lower plasma TEST (20.8-->7.8 nmol.L(-1), P<0.0001) and higher plasma E2 (168.1 327.3 pmol.L(-1), P < 0.002). Therewere no effects of E2 treatment upon any of the other measured variables including muscle glycogen: (E2 - PRE = 529.3 --> POST = 237.9; PL-PRE = 582.2 --> POST = 262.4 mmol.kg(-1) [dm]). We concluded that short-term E2 treatment increased plasma E2 to female follicular levels in males but had no effect upon lipid or carbohydrate metabolism.

Adolescent↗
PubMed2001

Short-term 17beta-estradiol decreases glucose R(a) but not whole body metabolism during endurance exercise.

The female sex hormone 17beta-estradiol (E(2)) has been shown to increase lipid and decrease carbohydrate utilization in animals. We administrated oral E(2) and placebo (randomized, double blind, crossover) to eight human male subjects for 8 days ( approximately 3 mg/day) and measured respiratory variables, plasma substrates, hormones (E(2), testosterone, leptin, cortisol, insulin, and catecholamines), and substrate utilization during 90 min of endurance exercise. [6,6-(2)H]glucose and [1,1,2,3,3-(2)H]glycerol tracers were used to calculate substrate flux. E(2) administration increased serum E(2) (0.22 to 2.44 nmol/l, P < 0.05) and decreased serum testosterone (19.4 to 11.5 nmol/l, P < 0.05) concentrations, yet there were no treatment effects on any of the other hormones. Glucose rates of appearance (R(a)) and disappearance (R(d)) were lower, and glycerol R(a)-to-R(d) ratio was not affected by E(2) administration. O(2) uptake, CO(2) production, and respiratory exchange ratio were not affected by E(2); however, there was a decrease in heart rate (P < 0.05). Plasma lactate and glycerol were unaffected by E(2); however, glucose was significantly higher (P < 0. 05) during exercise after E(2) administration. We concluded that short-term oral E(2) administration decreased glucose R(a) and R(d), maintained plasma glucose homeostasis, but had no effect on substrate oxidation during exercise in men.

Adult↗
PubMed2001

Writing your curriculum vitae.

Your curriculum vitae (CV) is your gateway to shortlisting. A good CV takes a long time to prepare. It should not only record your training but, more importantly, should reflect your 'physicianly' qualities, management skills and knowledge of health-care systems.

Career Mobility↗
PubMed2001

Provide a service ... then get paid.

Receiving payment at the time of dental treatment may be a new--even foreign--concept to dentists today. But more and more practices are finding it necessary to enforce such payment policies to keep a practice viable. Sometimes, it's just a matter of establishing policies within a practice; in other cases, it pays to enlist the services of a dental financing company for patient collections.

Accounting↗
PubMed2000

Timing of events in normal swallowing: a videofluoroscopic study.

Dynamic videofluoroscopic swallow studies were performed on 60 normal adult volunteers to establish normative data for clinically useful timing measures. The relation of swallowing gesture timing to the timing of actual bolus transit was of particular interest because it provides insight into the physiology of larger bolus volume accommodation. Parameters evaluated include the timing of bolus pharyngeal transit, soft palate elevation, aryepiglottic fold elevation and supraglottic closure, arrival of the bolus in the vallecula, hyoid bone displacement onset and duration, arrival of the bolus at the pharyngoesophageal sphincter, maximum pharyngeal constriction, and pharyngoesophageal sphincter opening. These parameters represent events required for normal deglutition, can be used to identify abnormalities in dysphagic patients, and provide a basis for comparison of swallowing performance both within and between patients. In addition, our experience has shown them to be reliably obtained. Other investigators have reported some of the measurements. However, to our knowledge, normative data for timing of aryepiglottic fold elevation, soft palate elevation and closure, and maximum pharyngeal constriction have not been described. Other measures included in the present study may provide alternatives when conventional measures cannot be obtained in selected patients. The relevance and clinical utility of new and alternative measures, in particular, are discussed.

Adolescent↗
PubMed2000

Structural displacements in normal swallowing: a videofluoroscopic study.

Dynamic videofluoroscopic swallow studies were performed on 60 normal adult volunteers to establish normative data for displacement of upper aerodigestive tract structures during deglutition. Variables evaluated included hyoid bone displacement, larynx-to-hyoid bone approximation, pharyngeal constriction, and the extent of pharyngoesophageal sphincter (PES) opening during liquid swallows of 1, 3, and 20 cc. Results showed direct relationships between bolus size and hyoid displacement, between bolus size and PES opening, and between bolus size and pharyngeal constriction. Only hyoid-to-larynx approximation remained unchanged across bolus sizes. Sex differences were noted for all variables except PES opening. Reliability for most measurement variables was excellent. To our knowledge, normative data for pharyngeal constriction and larynx-to-hyoid approximation have not previously been described.

Adolescent↗