Search PubMed⌕ Search

Biomedical subjects

C Thornton

Publications and source records attributed to C Thornton.

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

Obsessive compulsive comorbidity in the dieting disorders.

OBJECTIVE: This study investigated the comorbidity of obsessive compulsive disorder and obsessive compulsive personality disorder with the dieting disorders. A comorbid sample was examined in order to test the hypothesis that obsessive compulsive symptoms and personality are premorbid in these patients. METHOD: Sixty-eight inpatients (35 with anorexia nervosa and 33 with bulimia nervosa) were assessed for DSM-III-R Axis 1 and Axis 11 obsessive compulsive psychopathology using the Composite International Diagnostic Interview (CIDI) and the Personality Disorders Inventory (PDE), respectively. RESULTS: Twenty-one percent of the group met criteria for a diagnosis of obsessive compulsive disorder. Thirty-seven percent of anorexia nervosa patients were comorbid for obsessive compulsive disorder compared to only 3% of bulimia nervosa patients. In most, the obsessive compulsive disorder had predated the dieting disorder. Nineteen percent of patients were found to have premorbid obsessive compulsive personality disorder. DISCUSSION: This study supports the assumption of obsessive compulsive comorbidity within the dieting disorders and provides empirical support that this obsessionality is a premorbid characteristic.

Adolescent↗
PubMed1997

Effect of schedule on reactogenicity and antibody persistence of acellular and whole-cell pertussis vaccines: value of laboratory tests as predictors of clinical performance.

The performance of four acellular pertussis vaccines containing between two and five pertussis antigens combined with diphtheria and tetanus toxoids was compared with that of British whole-cell diphtheria/tetanus/pertussis (DTP) vaccine both in laboratory assays for potency, toxicity and immunogenicity, and for reactogenicity and immunogenicity in infants. Clinical responses were evaluated in double blind randomized Phase II trials using 3/5/9 month and 2/3/4 month schedules. The acellular DTPs had much lower toxicity than whole-cell DTP in laboratory tests and were significantly less pyrogenic than whole-cell DTP under both schedules. Local reactions were not consistently lower in acellular than whole-cell vaccinees and varied with the source of the diphtheria and tetanus antigens used. Differences in endotoxin level and content of active pertussis toxin (PT) between acellular DTP vaccines were not clinically significant. The reactogenicity advantage of the acellular vaccines was substantially reduced under the 2/3/4 month schedule due to the reduced reactogenicity of the whole-cell DTP vaccine when given at a younger age. There was no relationship between antigen content measured in micrograms per dose and ELISA antibody responses to filamentous haemagglutinin (FHA) and PT in infants, nor was murine immunogenicity predictive of immunogenicity in humans. Antibody response to PT was attenuated in the whole-cell group under the 2/3/4 month schedule but was unaffected in the group receiving acellular vaccines with individually purified components; antibody response to pertactin (69 kDa antigen) was similar in recipients of the whole-cell and component acellular vaccines under the 2/3/4 month schedule. PT antibody persistence until 4-5 years of age was significantly better in recipients of the component acellular than either the whole-cell vaccine or the co-purified acellular vaccine under the 3/5/9 month schedule. However, diphtheria antitoxin levels were reduced in acellular vaccine recipients under both schedules. Despite significantly lower tetanus potencies of the acellular vaccines in laboratory tests, no differences were found in tetanus anti-toxin responses in children.

Antibodies, Bacterial↗
PubMed1997

Trading spaces: computation, representation, and the limits of uninformed learning.

Some regularities enjoy only an attenuated existence in a body of training data. These are regularities whose statistical visibility depends on some systematic recoding of the data. The space of possible recoding is, however, infinitely large--it is the space of applicable Turing machines. As a result, mappings that pivot on such attenuated regularities cannot, in general, be found by brute-force search. The class of problems that present such mappings we call the class of "type-2 problems." Type-1 problems, by contrast, present tractable problems of search insofar as the relevant regularities can be found by sampling the input data as originally coded. Type-2 problems, we suggest, present neither rare nor pathological cases. They are rife in biologically realistic settings and in domains ranging from simple animat (simulated animal or autonomous robot) behaviors to language acquisition. Not only are such problems rife--they are standardly solved! This presents a puzzle. How, given the statistical intractability of these type-2 cases, does nature turn the trick? One answer, which we do not pursue, is to suppose that evolution gifts us with exactly the right set of recording biases so as to reduce specific type-2 problems to (tractable) type-1 mappings. Such a heavy-duty nativism is no doubt sometimes plausible. But we believe there are other, more general mechanisms also at work. Such mechanisms provide general (not task-specific) strategies for managing problems of type-2 complexity. Several such mechanisms are investigated. At the heart of each is a fundamental poly--namely, the maximal exploitation of states of representation already achieved by prior, simpler (type-1) learning so as to reduce the amount of subsequent computational search. Such exploitation both characterizes and helps make unitary sense of a diverse range of mechanisms. These include simple incremental learning (Elman 1993), modular connectionism (Jacobs et al. 1991), and the developmental hypothesis of "representational redescription" (Karmiloff-Smith 1979; 1992). In addition, the most distinctive features of human cognition--language and culture--may themselves be viewed as adaptations enabling this representation/computation trade-off to be pursued on an even grander scale.

Humans↗
PubMed1997

Auditory evoked response, median frequency and 95% spectral edge during anaesthesia with desflurane and nitrous oxide.

We have studied in 12 patients the effect of desflurane in nitrous oxide on the electroencephalogram (EEG) and the early cortical auditory evoked response (AER). After induction with desflurane, patients' lungs were ventilated to maintain three different end-expiratory concentrations of desflurane (1.5, 3 and 6%) during four consecutive 10-min periods before surgery. As the end-expiratory concentration of desflurane was increased, Pa and Nb (AER) amplitudes decreased and their latencies increased, and spontaneous EEG showed an increase in amplitude and a slowing of frequency. A linear relationship was demonstrated between log10 concentration of desflurane and all variables (P = 0.001). Pa amplitude showed the greatest linearity followed by the derived variable F95 of the EEG. From regression slopes, mean percentage changes of each variable were calculated for a 1 MAC change in desflurane concentration, Pa amplitude showed the largest change (mean 49% (95% confidence interval 40-56%) decrease for a 1 MAC increase). This was greater than that of F95 for a similar confidence interval, indicating better resolution. This study confirms that the early cortical AER is affected by desflurane in a similar manner to that of other anaesthetic agents and as such remains the most promising EEG derived measure of depth of anaesthesia.

Adult↗
PubMed1997

Expression of elongation factor-1 alpha and S1 in young and old human skeletal muscle.

Previous research has indicated that reduced expression of elongation factor-1 alpha (EF-1 alpha) may be an important determinant of the reduced rate of protein synthesis in senescent animals and cultured cells. The present study examined whether expression of EF-1 alpha or S1, a homologous protein found exclusively in postmitotic tissues, is reduced in senescent human skeletal muscle. Muscle biopsies were obtained from the vastus lateralis muscles of healthy young (22-31 yr old) and old (61-74 yr old) subjects. As reported previously, myofibrillar protein synthesis was approximately 40% slower in the older muscle (p < .001) as determined by incorporation of a stable isotope. Immunoblotting revealed no difference in the concentration of EF-1 alpha + S1 between younger and older muscle. RT-PCR assays indicated that S1 mRNA was much more abundant than EF-1 alpha mRNA in muscles of both age groups, with no reduction in either EF-1 alpha or S1 mRNA abundance in older muscles. We conclude that expression of EF-1 alpha and S1 is not diminished in older muscles and does not explain the age-related slowing of protein synthesis in human skeletal muscle. However, we cannot exclude the possibility that the activity of these proteins declines during senescence due to post-translational modifications.

Adult↗
PubMed1997

Insulin-like growth factor-I, actin, and myosin heavy chain messenger RNAs in skeletal muscle after an injection of growth hormone in subjects over 60 years old.

Growth hormone (GH) increases the amount of insulin-like growth factor-I (IGF-I) mRNA in rat skeletal muscle, but this effect has not been demonstrated in human muscle. An autocrine effect of IGF-I produced in muscle may be an important determinant of the increased muscle mass associated with GH therapy. Thus, we examined IGF-I mRNA abundance in skeletal muscle biopsy samples taken 10 h after a subcutaneous injection of GH (0.03 mg/kg, n = 6) or placebo (normal saline, n = 5) in men and women over 60 years of age. Relative tissue concentrations of IGF-I mRNA were evaluated with a competitive reverse transcriptase-polymerase chain reaction assay. Mean plasma IGF-I concentrations rose steadily after the GH injection, and were 74% higher in the GH group than in the control group at the time of the muscle biopsies. There was no consistent difference between the GH and control groups in muscle IGF-I mRNA abundance when expressed in relation to total RNA or polyadenylated RNA. However, one GH-treated subject had three times more IGF-I mRNA, relative to polyadenylated RNA, than the average control subject. There was no effect of GH on levels of mRNAs encoding the most abundant myofibrillar proteins, actin and myosin heavy chain. These data do not support the hypothesis that increased IGF-I mRNA abundance in skeletal muscle is required for the anabolic effect of GH in people over 60 years of age.

Actins↗
PubMed1997

Experiences of physical and sexual abuse in Australian general practice attenders and an eating disordered population.

OBJECTIVE: To determine the reported rates of child physical and sexual abuse experienced by hospitalised eating disordered patients compared to a control group of women attending general practitioners. METHOD: A retrospective survey using the self-report Finkelhor Sexual Life Events Inventory and clinical reports. RESULTS: Nearly one-half of eating disordered patients reported a history of child sexual abuse and one-quarter reported child physical abuse. These rates were significantly higher than those reported by the control group. CONCLUSIONS: Direct questioning regarding trauma histories is warranted when assessing patients with eating disorders and attention to such issues should be incorporated into the total management plan.

Adolescent↗
PubMed1997

The effects of predetermined payment rates for Medicare home healthcare.

OBJECTIVE: To assess the effects of an alternative method of paying home health agencies for services to Medicare beneficiaries, based on a demonstration program. DATA SOURCES/STUDY SETTING: Primary and secondary data collected on participating home health agencies in five states and their patients during the three-year demonstration period. Primary data included patient surveys at discharge and six months later, and two rounds of interviews with executive staff of the agencies. Secondary data included agencies' Medicare cost reports, quality assurance reviews, Medicare claims data, demonstration claims data, demonstration patient intake forms, and plan of treatment forms. STUDY DESIGN: The 47 agencies volunteering to participate in the demonstration were each randomly assigned to the treatment or control group. Treatment group agencies were paid a predetermined rate based on their inflation-adjusted cost per visit during the year preceding the demonstration; control group agencies were paid under Medicare's conventional cost reimbursement method. Demonstration impacts were estimated by comparing outcomes for the two groups of agencies and their respective patients, using regression models to control for any remaining differences. PRINCIPAL FINDINGS: Agencies paid under prospective rate setting were slightly better at holding per-visit cost increases below inflation than were control group agencies. The change in payment method had no effect on agencies' volume of Medicare visits or quality of care, nor on patients' use of Medicare services or other formal or informal care services. CONCLUSION: Changing from cost-based reimbursement to predetermined payment rates for Medicare home healthcare visits would not lead to large savings for the Medicare program, but would not increase costs to Medicare or adversely affect patients or their caregivers.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1996

A focus group inquiry into the perceptions of primary health care teams and the provision of health care for adults with a learning disability living in the community.

This study addresses the primary health needs of adults with learning disabilities living in the community. Policies specific to this client group and incorporating the ideology of normalization are noted and evidence of their implementation is sought. Previous research suggests that the adoption of a social rehabilitative model of care may have resulted in the neglect of health care needs. The recent closure of a local, subnormality hospital provided a critical situation and context for the study. The research question is, how do primary health care teams perceive the needs of adults with learning disabilities living in the community, and are they meeting their needs? Three primary health care teams formed the sample and data were obtained through semi-structured, focus group interviews. A conceptual framework developed early in the study influenced both the interview guide and the data analysis. The study suggests that practitioners working within primary health care teams have a limited awareness of the health care needs of adults with learning disabilities. Contributing factors were identified and include: negative attitudes towards the concept of normalization; inadequate education; a shortfall in financial and human resources; and poor collaboration with the specialist team.

Adult↗
PubMed1996

Utility of creatinine excretion in body-composition studies of healthy men and women older than 60 y.

This study evaluated whether aging alters the usefulness of creatinine excretion as an index of lean body mass (LBM) or muscle mass in healthy men and women. Creatinine excretion was determined while 24 young (15 men and 9 women aged < 32 y) and 38 older (23 men and 15 women aged > 60 y) healthy volunteers stayed at a clinical research center for 3 d. Total LBM was determined by 40K counting in all subjects, and cross-sectional areas of upper arm and thigh muscles were determined in some subjects (10 young, 20 old) by magnetic resonance imaging. The slopes and intercepts of the regression equations relating LBM to average daily creatinine excretion were the same in the younger and older groups, and the precision with which LBM could be determined from creatinine excretion was not diminished by aging. Creatinine excretion was closely correlated with cross-sectional areas of upper arm (r = 0.85) and thigh (r = 0.88) muscles, and the slopes and intercepts of the regression equations were not significantly affected by age. The older group had a mean LBM smaller than that of the younger group, which was accounted for entirely by a smaller muscle mass. Mean resting metabolic rate (RMR), whole-body protein turnover rate, and thigh strength were lower in the older group than in the young group. Adjustment of RMR and protein turnover for creatinine excretion or LBM eliminated the age effects. Strength was lower in the older group even after adjustment for creatinine excretion or LBM. This study indicates that creatinine excretion is useful for evaluating body composition in both young and old subjects.

Adult↗
PubMed1996

Effect of suxamethonium on the auditory evoked response in humans.

We have studied the arousal effect of suxamethonium on the auditory evoked response (AER) of the electroencephalogram (EEG) in 40 ASA I and II patients during isoflurane anaesthesia. After induction of anaesthesia, the patient's lungs were ventilated for 20 min with 0.6 MAC end-expiratory isoflurane (0.59-0.77% depending on the age of the patient), and 50% nitrous oxide in oxygen. The patients were then allocated randomly to one of two groups: 21 received suxamethonium 1 mg kg-1, while 19 were given saline. The AER before and after administration of suxamethonium or saline was compared to determine the changes in Pa and Nb amplitudes and latencies. Pa amplitude after suxamethonium increased by 53% (95% confidence interval (CI) 15, 104%) compared with a reduction in Pa amplitude in the saline group of 19% (95% CI, -41, 12%) (P = 0.004) suggesting an arousal effect. Similarly, Nb amplitude increased in the suxamethonium group by 47% (95% CI, 3, 110%) and decreased in the saline group by 11% (95% CI, -33, 19%) (P = 0.03). We conclude that suxamethonium caused arousal according to the AER and postulate that this may have been caused by increased muscle afferent activity after stimulation of muscle spindles, although further studies are required to confirm this.

Adolescent↗
PubMed1996

Effect of neuromuscular block on depth of anaesthesia as measured by the auditory evoked response.

In a double-blind, randomized, controlled, prospective study, we have investigated the effects of vecuronium and laryngoscopy on the auditory evoked response (AER) of the electroencephalogram (EEG) in 40 ASA I and II patients under steady state anaesthesia. After stable anaesthesia had been achieved with 1.0 MAC of isoflurane and nitrous oxide in oxygen, patients were allocated randomly to receive two separate doses of vecuronium 0.05 mg kg-1 or saline. The AER was recorded before and after each dose and then after 20-s laryngoscopy in each group to determine any changes in the early cortical components of the AER waveform (Pa and Nb). There were no statistically significant changes between the vecuronium and saline groups. However, there was a statistically significant increase in mean Pa amplitude of 36% (P = 0.008) and a reduction in mean Nb latency of 6% (P = 0.05) after laryngoscopy in both the paralysed and unparalysed groups, and these changes did not differ significantly between groups. There were correspondingly significant haemodynamic responses to laryngoscopy in both groups. We conclude that neuromuscular block with vecuronium does not affect depth of anaesthesia as measured by the AER in either stimulated or unstimulated patients. In addition, we have demonstrated clearly the arousal effect of laryngoscopy on the AER.

Adult↗
PubMed1996

Remifentanil reduces auditory and somatosensory evoked responses during isoflurane anaesthesia in a dose-dependent manner.

We studied 60 patients during stable isoflurane anaesthesia (0.4 MAC) after premedication with temazepam. Patients were allocated randomly to one of three dose regimens of remifentanil: 1 microgram kg-1 i.v. over 1 min and an infusion of 0.2 microgram kg-1 min-1 (low dose); 2.5 micrograms kg-1 and 0.5 microgram kg-1 min-1 (medium dose); and 5 micrograms kg-1 and 1 microgram kg-1 min-1 (high dose). The auditory (AER) and median nerve somatosensory (SER) responses were elicited throughout, and recorded before and after tracheal intubation, and surgical incision, together with systolic and diastolic arterial pressure and heart rate. Venous blood concentrations of remifentanil were measured at the above times. After administration of remifentanil, Pa and Nb amplitudes of the AER increased at the low dose, remained constant at the medium dose and decreased at the high dose. This dose-related effect was linear and significant (P = 0.012, P = 0.05). Pa amplitude correlated inversely with remifentanil blood concentrations before and after intubation and incision (P = 0.002, P < 0.001, P < 0.001 and P < 0.001). In the SER, P15-N20 amplitudes decreased after administration of remifentanil (P < 0.001), whereas P25-N35 and N35-P45 amplitudes increased at all dose concentrations (P < 0.001 and P < 0.001). After intubation, P15-N20 and N35-P45 amplitudes increased at the low dose, did not change at the medium dose and decreased at the high dose (P = 0.001, P = 0.027). After remifentanil, systolic and diastolic arterial pressure and heart rate decreased in a linearly dose-related manner (P = 0.033, P < 0.001, P < 0.001). At all doses the three variables increased after intubation (P = 0.001, P < 0.001, P < 0.01), and systolic and diastolic arterial pressure increased after incision (P = 0.027, P = 0.039).

Adjuvants, Anesthesia↗
PubMed1996

Effect of age on muscle hypertrophy induced by resistance training.

BACKGROUND: Previous research has shown that resistance training induces muscle hypertrophy in older subjects, but has not clarified whether the degree of hypertrophy is affected by age. The present study was done to test the hypothesis that men and women over 60 years old have a smaller hypertrophic response to resistance training than young adults. METHODS: Cross-sectional areas (CSA) of muscle in the thigh and upper arm were determined before and after 3 months of progressive resistance training by magnetic resonance imaging (MRI) in 9 young (22-31 yr, 5 male and 4 female) and 8 old (62-72 yr, 4 male and 4 female) subjects. Strength was determined by 3-repetition-maximum (3RM) testing. The amount of weight lifted during the training program was proportional to baseline strength. RESULTS: Mean pretraining 3RM strength, per cm2 CSA, was less in the older group for all muscle groups examined (16 +/- 6% for elbow flexors, p < .02; 40 +/- 7% for knee flexors, p < .001; 19 +/- 9% for knee extensors, p < .05). Mean training-induced increases in muscle CSA were less in the older group for elbow flexors (22 +/- 4% in young, 9 +/- 4% in old, p < .05) and knee flexors (8 +/- 2% in young, 1 +/- 2% in old, p < .01), but not for knee extensors (4 +/- 1% in young, 6 +/- 2% in old). Mean training-induced increases in specific tension (ratio of 3RM strength to CSA) were similar in young and old groups for elbow flexors (21 +/- 5% in young, 19 +/- 5% in old) and knee extensors (38 +/- 6% in young, 32 +/- 14% in old), but were greater in the older group for knee flexors (28 +/- 5% in young, 64 +/- 13% in old, p < .02). CONCLUSIONS: Aging can attenuate the hypertrophic response of muscle groups to resistance training, when the training load is proportional to baseline strength. However, aging does not impair training-induced increases in specific tension.

Adult↗
PubMed1996

Spontaneous movement after injection of propofol.

Spontaneous movement following injection of propofol at induction was studied in 303 patients. Two hundred patients were Caucasians and 103 were Asians. In a pilot study carried out prior to the main study, 26% of the Asians moved at induction as compared with 6% of the Caucasians. The patients were studied in relation to a number of variables; age, sex, weight, height, race, smoker/non smoker, vegetarian/non vegetarian, alcohol consumption, premedication, use of fentanyl at induction and dose of propofol. When race was included as the sole variable there was a marginal but not significant difference between the two groups in terms of movement (p = 0.06). However, when the other recorded variables were taken into account, race was not included as a predictor of whether or not the patient moved. The best model for predicting whether the patients moved or not combines the variables weight and dose of propofol. Patients were more likely to move if they were lighter and the dose of propofol used at induction was higher.

Adult↗