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Biomedical subjects

S Curtis

Publications and source records attributed to S Curtis.

At least 55 records · Page 3Linked to original sources
PubMed1997

Abnormalities of skeletal muscle metabolism in patients with chronic heart failure: evidence that they are present at rest.

OBJECTIVE: To investigate abnormalities of skeletal muscle metabolism in patients with congestive heart failure. SETTING: A university teaching hospital. METHODS: 43 patients (22 New York Heart Association (NYHA) grade II, 21 grade III) and 10 controls were studied. A forearm model of muscle metabolism was used, with a cannula inserted retrogradely into an antecubital vein of the dominant forearm. Maximum voluntary contraction (MVC) was measured using handgrip dynamometry. Subjects performed handgrip exercise, 5 s contraction followed by 5 s rest for 5 min at 25%, 50%, and 75% of MVC or until exhaustion. Blood was taken at rest and 0 and 2 min after exercise for measurement of lactate and ammonia. After 30 min the procedure was repeated with fixed workloads of 7 kg, 14 kg, and 21 kg. RESULTS: MVC (kg, mean (SEM)) was lower in patients than in controls (control 42.45 (2.3); NYHA II 34.13 (1.3), P = 0.003; NYHA III 33.13 (1.94), P = 0.008). Resting lactate (mmol/l) was higher in patients than controls (control 0.65 (0.06); NYHA II 0.84 (0.08), P = 0.13; NYHA III 1.18 (0.1), P = 0.002). Resting ammonia (mumol/l) was higher in NYHA III (65.7 (6.0)) than in NYHA II (48.0 (3.7), P = 0.016); no difference was found between controls (48.0 (7.1)) and patients. The overall lactate and ammonia response to exercise was greater in NYHA III than in NYHA II and controls (P < 0.05). At volitional exhaustion, peak lactate (mmol/l: NYHA III 3.31 (0.26); NYHA II 2.56 (0.16); controls 2.71 (0.22); P = 0.022 NYHA III v NYHA II) and ammonia (mumol/l: NYHA III) 126.4 (8.97); NYHA II 92.9 (7.23); controls 109 (16.3); P = 0.006 NYHA III v NYHA II) were higher in severe congestive heart failure. CONCLUSIONS: Skeletal muscle metabolism is abnormal at rest in congestive heart failure. During exercise, the degree of metabolic abnormality is related to the symptomatic status of the patient.

Adult↗
PubMed1997

High prevalence of allergic sensitization in children with habitual snoring and obstructive sleep apnea.

STUDY OBJECTIVE: To determine whether allergic sensitization occurs frequently in children with habitual snoring and whether allergy predicts the occurrence of obstructive sleep apnea syndrome (OSAS) in snoring children. DESIGN: Prospective study of 39 children with habitual snoring who were referred for polysomnography. SETTING: Pediatric pulmonary sleep disorders clinic in a tertiary referral center. MEASUREMENTS: Subjects underwent a complete history and physical examination. To assess for the presence of allergic sensitization, a multiantigen radioallergosorbent test (RAST) was performed on serum samples. Subjects then underwent nocturnal polysomnography to determine the presence and severity of OSAS. RESULTS: Fourteen subjects (36%) demonstrated sensitivity to allergens; this is higher than expected for the general pediatric population. The frequency of OSAS was increased in subjects with positive RAST results compared to those with negative RAST results (57% vs 40%; chi 2 = 9.11; p < 0.01). CONCLUSION: Allergy is frequently present in pediatric patients with habitual snoring. Furthermore, the presence of allergy is associated with an increased risk of OSAS in this population.

Child↗
PubMed1997

Caught in the "traps of managed competition"? Examples of Russian health care reforms from St. Petersburg and the Leningrad region.

Elements of a "managed market" for health services have been introduced into the Russian health care system, which under the Soviet regime was run as a comprehensive state-managed system. The authors examine the recent development of health service reforms in a case study of the city of St. Petersburg and the surrounding Leningrad region. Evidence from key informants and a local survey of service users shows how alternative models of the managed market are being introduced in different parts of the study area. A critical review of the market-oriented strategies for reform emerging in the case study suggests that such reforms carry risks associated with the "traps of managed competition." Future policy for health service systems in Russia must take these risks more fully into account.

Adolescent↗
PubMed1996

Evaluation of pulmonary function and polysomnography in obese children and adolescents.

Obese adults have an increased prevalence of pulmonary disorders. Although childhood obesity is a common problem, few studies have evaluated the pulmonary complications of obesity in the pediatric population. We, therefore, performed pulmonary function tests (PFTs), polysomnography, and multiple sleep latency tests (MSLTs) in 22 obese children and adolescents [mean age, 10 +/- 5 (SD) years; 73 percent female; 184 +/- 36 percent ideal body weight], none of whom presented because of sleep or respiratory complaints. PFTs were normal in all but two subjects. Ten (46 percent) subjects had abnormal polysomnograms. There was a positive correlation between the degree of obesity and the apnea index (r = 0.47, P < 0.05), and an inverse correlation between the degree of obesity and the Sa0(2) nadir (r = -0.60, P < 0.01). The degree of sleepiness on MSLT correlated with the degree of obesity (r = -0.50, P < 0.05). We conclude that obese children and adolescents have a high prevalence of sleep-disordered breathing, although in many cases it is mild. Obstructive sleep apnea syndrome (OSAS) improved following tonsillectomy and adenoidectomy. We recommend that pediatricians have a high index of suspicion for OSAS when evaluating obese patients, and that polysomnography be considered for these patients.

Adolescent↗
PubMed1996

The effect of glycogen availability on power output and the metabolic response to repeated bouts of maximal, isokinetic exercise in man.

The relationship of glycogen availability to performance and blood metabolite accumulation during repeated bouts of maximal exercise was examined in 11 healthy males. Subjects performed four bouts of 30 s maximal, isokinetic cycling exercise at 100 rev.min-1, each bout being separated by 4 min of recovery. Four days later, all subjects cycled intermittently to exhaustion [mean (SEM) 106 (6) min] at 75% maximum oxygen uptake (VO2max). Subjects were then randomly assigned to an isoenergetic low-carbohydrate (CHO) diet [7.8 (0.6)% total energy intake, n = 6] or an isoenergetic high-CHO diet [81.5 (0.4)%, n = 5], for 3 days. On the following day, all subjects performed 30 min cycling at 75% VO2max and, after an interval of 2 h, repeated the four bouts of 30 s maximal exercise. No difference was seen when comparing total work production during each bout of exercise before and after a high-CHO diet. After a low-CHO diet, total work decreased from 449 (20) to 408 (31) J.kg-1 body mass in bout 1 (P < 0.05), from 372 (15) to 340 (18) J.kg-1 body mass in bout 2 (P < 0.05), and from 319 (12) to 306 (16) J.kg-1 body mass in bout 3 (P < 0.05), but was unchanged in bout 4. Blood lactate and plasma ammonia accumulation during maximal exercise was lower after a low-CHO diet (P < 0.001), but unchanged after a high-CHO diet. In conclusion, muscle glycogen depletion impaired performance during the initial three, but not a fourth bout of maximal, isokinetic cycling exercise. Irrespective of glycogen availability, prolonged submaximal exercise appeared to have no direct effect on subsequent maximal exercise performance.

Adult↗
PubMed1996

Predictors of persistence and remission of ADHD into adolescence: results from a four-year prospective follow-up study.

OBJECTIVE: To evaluate the predictors of persistence and the timing of remission of attention-deficit hyperactivity disorder (ADHD). METHOD: Subjects were 6- to 17-year old Caucasian, non-Hispanic boys with and without ADHD. DSM-III-R structured diagnostic interviews and blind raters were used to examine psychiatric diagnoses, cognitive achievement, social, school, and family functioning at a 4-year follow-up assessment. RESULTS: At the 4-year follow-up assessment, 85% of children with ADHD continued to have the disorder and 15% remitted. Of those who remitted, half did so in childhood and the other half in adolescence. Predictors of persistence were familiality of ADHD, psychosocial adversity, and comorbidity with conduct, mood, and anxiety disorders. CONCLUSIONS: The findings prospectively confirm that the majority of children with ADHD will continue to express the disorder 4 years later. For a minority of children, ADHD was a transient disorder that remits early in development. In addition, we have shown that persistence of ADHD is predictable. Familiality, adversity, and psychiatric comorbidity may be clinically useful predictors of which children with ADHD are at risk for a persistent disorder.

Achievement↗
PubMed1996

Modelling inequality in reported long term illness in the UK: combining individual and area characteristics.

STUDY OBJECTIVE: To assess the nature of the relation between health and social factors at both the aggregated scale of geographical areas and the individual scale. DESIGN AND SETTING: The individual data are derived from the sample of anonymised records (SAR) from the census of 1991 in Great Britain, and are combined with area data from this census. The ecological setting (context) was defined using multivariate methods to classify the 278 districts of residence identifiable in the SAR. The outcome health variable is the 1991 census long-term limiting illness question. Health variations were analysed by multilevel logistic regression to examine the compositional variation (at the level of the individual) and the contextual variation (variability operating at the level of districts) in reported illness. PARTICIPANTS: 10 per cent randomised subsample of the SAR who are aged 16+ and are resident in households. MAIN RESULTS: The multi-level modelling revealed that area factors have a significant association with individual health outcome but their effect is smaller than that of individual attributes. The results show evidence for both compositional and contextual effects in the pattern of variation in propensity to report illness. CONCLUSIONS: The results suggest generally higher levels of ill health for individuals who are older, not married, in a semi/unskilled manual social class, and socioeconomically deprived (as measured by a composite deprivation score). All individuals living in areas with high levels of illness (which tend to be more deprived areas) show greater morbidity, even after allowing for their individual characteristics. However, within affluent areas, where morbidity was generally lower, the health inequality (health gradient) between rich and poor individuals was particularly strong. We consider the implications of these findings for health and resource allocation policy.

Adolescent↗
PubMed1996

AANA Journal course: update for nurse anesthetists--genetic testing for malignant hyperthermia.

The "gold standard" for the determination of susceptibility to malignant hyperthermia has long been the caffeine-halothane-contracture test, which is costly and invasive. As the workings of molecular genetics are better understood, research is being applied to finding the causative gene for malignant hyperthermia. Once this gene is identified, genetic testing will involve a much simpler, less invasive test that uses blood samples to detect susceptibility. To reach this goal, researchers have been attempting to identify the deoxyribonucleic acid (DNA) mutations responsible for malignant hyperthermia by using techniques such as linkage analysis. Review of the literature reveals that malignant hyperthermia has been linked to the ryanodine receptor in swine and in some humans. It has also been linked to chromosome 19q12-13.1, which is where the gene encoding the ryanodine receptor lies. The literature further reveals that malignant hyperthermia may be a heterogeneous disorder, which means that more than one gene is responsible for its expression.

Chromosome Mapping↗
PubMed1995

Health care reforms in Russia: the example of St Petersburg.

This paper describes the changes being introduced into the Russian health care system, particularly the introduction of a compulsory social health insurance system which is paralleled by encouragement of independent health insurance. An example of the implementation of these changes is provided by the early developments in St Petersburg. The effects of the likely changes on health care providers and users are discussed. It is argued that in the light of these reforms, as well as change in other countries, a revision is necessary in the perspectives adopted by geographers of health care to compare national health systems.

Ambulatory Care Facilities↗
PubMed1995

The application of disability data from epidemiological surveys to the development of indicators of service needs for dependent elderly people.

Increases in the prevalence of disability due to the ageing of the population have given rise to the need for simple indicators which may be used to estimate service needs and to assess whether resources have been fairly distributed. The present study involved the validation of an indicator based on confinement level by reference to epidemiological studies of disability, social support, and living conditions in three regions of France. Using factorial correspondence analysis and regression methods it was found that such an indicator could adequately summarize more complex empirical observations and thus provide a means of classifying elderly populations into four dependency groups. While comparisons of the percentage of persons classified at each level with national data suggest that the observations from the three studies may be reasonably representative of France as a whole, the application of this indicator to other European countries should be preceded by a preliminary validation involving regional or national health survey data for each country. The use of this indicator should also be complemented by individual need assessment procedures.

Activities of Daily Living↗
PubMed1995

Amphetamine paired with physical therapy accelerates motor recovery after stroke. Further evidence.

BACKGROUND AND PURPOSE: In animal models of brain injury, administration of numerous pharmaceuticals is reported to facilitate functional recovery. However, only drugs that increase the release of norepinephrine have been shown to promote recovery when administered late (days to weeks) after injury. To determine whether these findings were applicable to humans, we administered the norepinephrine stimulant dextroamphetamine, paired with physical therapy, to hemiplegic stroke patients. METHODS: Ten hemiplegic patients who suffered an acute ischemic infarction were entered between days 16 and 30 after onset and randomly assigned to receive either 10 mg of dextroamphetamine or a placebo orally every fourth day for 10 sessions paired with physical therapy. The Fugl-Meyer Motor Scale was used at baseline, within each session, and for 12 months after onset as the dependent measure. Confounding medications such as alpha-adrenergic antagonists or agonists were excluded in all subjects. RESULTS: Although there were no differences between the groups at baseline (P = .599), there was a significant (P = .047) difference between the groups when the drug had been discontinued for 1 week and at the 12-month follow-up visit (P = .047). CONCLUSIONS: Administration of dextroamphetamine paired with physical therapy increased the rate and extent of motor recovery in a small group of hemiplegic stroke patients. These data support and extend previous findings of the facilitatory aspects of certain types of drugs on recovery from brain injury. The use of neuromodulation may allow the nervous system to adapt previously unused or alternative pathways to relevant external input.

Administration, Oral↗
PubMed1995

Inability of clinical history to distinguish primary snoring from obstructive sleep apnea syndrome in children.

STUDY OBJECTIVE: To determine whether primary snoring (PS) could be distinguished from childhood obstructive sleep apnea syndrome (OSAS) by clinical history. DESIGN: Retrospective study of clinical history of 83 children with snoring and/or sleep disordered breathing who were referred for polysomnography. SETTING: Tertiary referral center; pediatric pulmonary sleep apnea clinic. MEASUREMENTS: We evaluated the ability of a clinical obstructive sleep apnea (OSA) score and other questions about sleep, breathing, and daytime symptoms to distinguish PS from OSAS in children. Parents were asked about the child's snoring, difficulty breathing, observed apnea, cyanosis, struggling to breathe, shaking the child to "make him or her breathe," watching the child sleep, afraid of apnea, the frequency and loudness of snoring, and daytime symptoms such as excessive daytime sleepiness (EDS). RESULTS: Based on polysomnography results, 48 patients were classified as PS and 35 as OSAS. Peak endtidal CO2 (49 +/- 3.2 vs 55 +/- 8.2 [SD] mm Hg); lowest arterial oxygen saturation measured by pulse oximetry (95 +/- 1.9 vs 82 +/- 14%); and apnea/hypopnea index (0.27 +/- .3 vs 8.4 +/- 6 events/h) indicated that the diagnostic criteria for PS versus OSA were reasonable. There were no differences between PS and OSA patients with respect to age, sex, race, failure to thrive, obesity, history of EDS, snoring history, history of cyanosis during sleep, or daytime symptoms except for mouth breathing. There were no significant differences in sleep variables between PS patients and those with any severity of OSAS. The OSA score misclassified about one of four patients. Comparing PS and OSA patients, significant findings were daytime mouth breathing (61 vs 85%; p = 0.024); observed apnea (46 vs 74%; p = 0.013); shaking the child (31 vs. 60%; p = 0.01); struggling to breathe (58 vs 89%; p = 0.003); and afraid of apnea (71 vs 91%; p = 0.028). However, none of these were sufficiently discriminatory to predict OSAS. CONCLUSION: We conclude that PS in children cannot be reliably distinguished from OSAS by clinical history alone.

Case-Control Studies↗
PubMed1994

Coronary heart disease: trends in spatial inequalities and implications for health care planning in England.

The idea of health gain has recently received particular emphasis in health policy in England. One of the areas where there is considerable scope for health gain is in the reduction of mortality due to Coronary Heart Disease. Some reduction in mortality rates due to this cause have already been achieved in England in the 1980s. However, the change in standardised mortality rates varies around the country. A review of studies of geographies of declining CHD mortality shows that such geographical variation is typical of other countries which have recently experienced a reduction in the CHD epidemic. The paper presents the results of an analysis of change in spatial inequality in coronary heart disease mortality among the population aged 35-74 for the 190 District Health Authorities in England over the period 1982-1989. Data were derived from counts of cause-specific deaths and population estimates published by the Office of Population Censuses and Surveys. Various approaches were used to assess the change in spatial disparity which has accompanied the average overall reduction in mortality rates over the study period. The results show that the trends vary between age and sex groups in the population and that, particularly for older people, overall health gain across the country is being achieved at the cost of greater inequality in health between areas. The implications for local health strategies with respect to coronary heart disease reduction are discussed.

Adult↗
PubMed1994

Polysomnographic characteristics of patients with Rett syndrome.

During wakefulness, patients with Rett syndrome have disordered breathing. To understand further this ventilatory control disorder, we performed polysomnography in 30 patients with Rett syndrome and 30 control subjects (female subjects with primary snoring). The median age was 7 years (range, 1 to 32 years) for Rett syndrome and 6 years (range, 1 to 17 years) for control subjects. During periods of wakefulness, 67% of patients with Rett syndrome had the characteristic pattern of disordered breathing (i.e., episodes of hyperventilation followed by central apnea and desaturation). No such events occurred during sleep. Sleep efficiency and sleep architecture were similar for both groups. During sleep, there was no difference in duration of periodic breathing, number of episodes of central apnea with desaturation, or number of episodes of obstructive apnea or end-tidal carbon dioxide tension between the two groups. Although arterial oxygen saturation during rapid eye movement (REM) sleep was slightly lower in patients with Rett syndrome (nadir, 94% +/- 2% vs 96% +/- 2%), it remained within the normal range. Parental history reflected the awake respiratory findings in most cases. We conclude that patients with Rett syndrome have normal breathing during non-rapid eye movement (NREM) sleep. We speculate that patients with Rett syndrome have normal brain-stem control of ventilation, and that the disordered breathing seen during wakefulness is due to an abnormality of the cortical influence on ventilation.

Adolescent↗
PubMed1993

Improving the accuracy of a new articulator.

The indications and features of the new Denar Combi articulator are reviewed. The Combi articulator was designed primarily as a set path instrument, but can also be used as a semiadjustable or fully adjustable stereographic articular. The articulator can be programmed for any of these modes, but the Combi model is limited when used as a stereographic instrument according to the manufacturer's instructions, with the instrument-precipitated geometric errors. These errors were identified mathematically, and an accurate technique for the instrument is described.

Dental Articulators↗
PubMed1993

Gap junctional connections between hair cells, supporting cells and nerves in a vestibular organ.

The pattern of gap-junctional connections between cells in the vestibular neuroepithelium of the posterior semicircular duct of the alligator lizard are described based upon the study of freeze fracture replicas and ultrathin sections with a transmission electron microscope. Both type I and type II hair cells are coupled to adjacent supporting cells by a series of small macular gap junctions located in a ring around the hair cell at the level of the apical circumferential belt of actin filaments. Adjacent supporting cells are extensively interconnected by gap junctions. A few cases of gap junctions between afferent dendrites and supporting cells, and between afferent dendrites and calyceal nerve endings were seen. These morphological observations together with data from other studies in the literature suggest a possible role for supporting cells in altering the micromechanical properties of the hair cell receptor organs during stimulation.

Actin Cytoskeleton↗