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Biomedical subjects

S Curtis

Publications and source records attributed to S Curtis.

At least 73 records · Page 4Linked to original sources
PubMed1992

Changes in cortical activity when subjects scan memory for tones.

The magnetoencephalogram (MEG) was used to detect regional changes in spontaneous cortical activity accompanying short-term memory search. This method was chosen because magnetic fields are detectable only within a few centimeters of the projections of their sources onto the scalp. The specific hypothesis that auditory cortex is involved in scanning memory for tones was tested by sensing the field of the magnetic counterpart to N100 (N100m) which is known to originate in auditory cortex. N100m was measured at many different positions and the spontaneous cortical rhythms in the alpha bandwidth (8-12 Hz) were measured at the same places. These rhythms were found to be suppressed while subjects scanned memory for musical tones in a Sternberg paradigm. For 3 subjects, both the MEG suppression time (ST) and reaction time (RT) increased linearly with memory set size. The correlation between ST measured over the left hemisphere and set size was significant for two subjects but not significant for the third, and the slopes of the regression lines relating ST to set size were too shallow to be related to the time required to scan memory. However, the correlation between ST of the right hemisphere and set size was highly significant for all subjects, and the slopes of the regression lines were comparable to those relating RT to set size. The electroencephalogram (EEG) recorded with midline electrodes failed to reveal a significant relationship between suppression time and set size for 2 of the subjects, thus ruling out global alpha blockage and generalized arousal as the basis for the task-related suppression duration. The electric N100, measured at Cz, decreased significantly in amplitude with set size for 2 subjects, but it increased significantly in amplitude for the third subject. In contrast, RT increased with set size for all subjects. N100m measured over the right hemisphere was similar to the behavior of N100, while N100m measured over the left hemisphere showed little change in amplitude with set size, thus establishing an asymmetry in N100 between the hemispheres. Since N100 amplitude is normally larger when attention is paid to auditory stimuli, differential attention alone cannot account for the relation between ST and set size. Furthermore, the processing negativity, which may be superimposed on N100 in selective attention tasks, was not discernible for any set size. It was also found that ST prior to the button press was not correlated with RT. Hence, the covariation of set size with ST is not attributable to preparation for a motor response.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed1992

The role of diagnostic CT scanning of the brachial plexus and axilla in the follow-up of patients with breast cancer.

In order to assess the value of computed tomographic scanning of the axilla and brachial plexus in the management of patients with arm symptoms following treatment for breast cancer, the case notes and diagnostic films of 102 such patients who underwent scanning between 1985 and 1990 at this institution were analysed retrospectively. The clinical indications for requesting computed tomography (CT) of the brachial plexus and axilla included arm oedema (52 patients, 51%), brachial plexus neuropathy (73 patients, 72%), and/or the presence of a palpable axillary mass (18 patients, 18%). Of 102 CT scans, 80 showed either no abnormality (31 patients, 30%), or axillary fibrosis (49 patients, 48%), and 22 (21%) showed radiological evidence of recurrent tumour. Only 4 of 84 patients with no palpable mass had computed tomographic evidence of occult recurrent tumour; all of these had concurrent evidence of distant metastatic disease (lung, liver, bone). Patients have been followed up for from between 1 and 15 years from diagnosis (median 5.5 years). The extremely low yield of tumour recurrence on computed tomographic scanning in the absence of a palpable axillary mass (4/84 patients, 5%; 95% CI 1-12), cannot justify CT as a method of screening for clinically occult axillary relapse in patients with arm symptoms following axillary surgery and radiotherapy for breast cancer. Computed tomographic scanning in these patients should only be employed to confirm the clinical suspicion of tumour as a baseline prior to further treatment.

Axilla↗
PubMed1992

Promoting health through a developmental analysis of adolescent risk behavior.

Adolescents are the only U.S. population group not to improve morbidity and mortality since 1960. Social and behavioral etiologies of adolescent morbidity and mortality are best addressed in schools, since health care providers rarely are seen by teen-agers for other than organic health complaints. The relevance of physical, cognitive, and psychosocial development for adolescent risk-taking and their attendant health problems are discussed. Recognizing adolescent risk-taking as a means of achieving autonomy and identity, nurses and health educators can intervene to promote health-enhancing alternatives to achieve those ends. Social learning theory provides a basis for interventions to personalize the curricula, change behaviors, and shape the environment.

Adolescent↗
PubMed1991

Estrogen receptor stereochemistry: ligand binding and hormonal responsiveness.

Estrogen stimulation of the uterus produces a spectrum of biochemical responses that are customarily linked together. This report is an overview of a series of studies by our laboratory investigating the role of different ligand structures in eliciting hormonal responses. Diethylstilbestrol (DES) and certain structural analogs, indenestrol A (IA), indenestrol B (IB), and pseudo-DES, were used as probes to segregate various genomic responses previously considered interrelated, most notably the events of specific protein synthesis and DNA synthesis. These compounds have weak uterotrophic activity; however, they interact with high affinity specifically with mouse uterine estrogen receptors (ERs). All of them produce stoichiometrically similar amounts of ER complex in the nucleus. Indenestrol A and IB possess a single chiral carbon atom and exist as a mixture of enantiomers (ENTs). Competitive binding assays of pure ENTs and cytosolic ERs demonstrated a stereochemical chiral preference for the IA isomer but not IB. This preference was also evident from nuclear ER occupancy experiments. Biologic activity of the IA ENTs also demonstrated differences as seen by receptor binding. Ornithine decarboxylase (ODC) activity was stimulated 600% by DES and partially by IA (rac). All of the ODC activity produced by IA (rac) was due to the IA(C3)-S ENT. Uterine DNA synthesis was measured after treatment with the IA compounds. Indenestrol A (rac) increased DNA synthesis to 40% of the level seen with DES. The weak ENTs showed no activity and the active ENTs were weaker than the IA racemic. These compounds should be useful probes for studying the individual responses involved in estrogen-induced uterine growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Diethylstilbestrol metabolites and analogs: differential ligand effects on estrogen receptor interactions with nuclear matrix sites.

Estradiol (E), diethylstilbestrol (DES), and three structurally similar DES derivatives and analogs, consisting of racemic mixtures of indenestrol-A (IA; rac), indenestrol-B (IB; rac), and the Z-isomer of pseudo-DES (PD) were used as probes to determine the effect of ligand on receptor-nuclear acceptor site interactions. IA (rac), IB (rac), and Z-PD have been previously shown to interact with the mouse uterine estrogen receptor with high affinity (Kd, approximately 1.5-2.2 x 10(-10) M), occupy similar levels of receptor in the nucleus in vivo, and have nuclear retention times similar to those of E and DES. However, in spite of these similarities, they differentially stimulate estrogenic responses that were previously thought to be interrelated and obligatory for full estrogenic action. In an attempt to elucidate the mechanism of differential stimulation of estrogen-regulated responses, the temporal pattern of KCl-resistant receptor sites was examined after a single injection of E, DES, IA (rac), IB (rac), Z-PD, or saline. Z-PD displayed lower levels of KCl-resistant receptor than the other compounds, whereas IA (rac) and IB (rac) had patterns similar to those of E and DES. In cell-free binding assays, all of the different receptor-ligand complexes were equally effective at competitively inhibiting the binding of receptor-[3H]E complexes to mouse uterine nuclear matrix with a Ki of 1.1 x 10(-10) M. Direct binding analysis showed no difference in the number of nuclear binding sites (range, 40.4-63.9 fmol/100 micrograms DNA) or Kd (range, 1.3-1.8 x 10(-10) M) among the different receptor-ligand complexes. Dissociation studies performed at 4 C showed no differences among the different complexes. In contrast, Z-PD-receptor complexes dissociated much faster from matrix sites at 22 C than any of the other complexes. Significant differences were noted in the proportion of complexes that were resistant to extraction with 0.6 M KCl. Forty-three percent of receptor-E complexes and 44% of receptor-DES complexes were resistant to KCl extraction, while 61% of receptor-IA and 29% of receptor-PD complexes were resistant to extraction, paralleling their activity in eliciting some estrogenic responses. In contrast, no difference was seen by gel shift assays in the ability of the ligand-receptor complexes to bind to a specific PS2 estrogen-responsive DNA sequence. These results demonstrate that the ligand may significantly affect the interaction of the estrogen receptor with nuclear acceptor sites.

Animals↗
PubMed1991

Concentrations of serum constituents in cold-stressed calves from heifers fed inadequate protein and(or) energy.

A study with neonatal calves was conducted to determine the effects of maternal crude protein (CP) and(or) metabolizable energy (ME) malnutrition, cold stress (0 or 21 degrees C), and age on concentrations of selected serum constituents. For each of 2 yr, 60 artificially bred Angus heifers were assigned randomly to a 2 x 2 factorial nutritional plan 150 d before predicted parturition. The diets provided each heifer with either .32 or .96 kg/d of CP and 8.7 or 12.6 Mcal/d of ME. Blood samples were obtained from heifers at parturition and from their calves at birth and at 12, 24, 36, 48, and 72 h of age. Sera were analyzed for concentrations of blood urea nitrogen (BUN), creatinine (Creat), iron, total protein (TProt), alkaline phosphatase (AlkPhos), total bilirubin (TBil), and cholesterol (Chol). Mean correlations of these constituents in calf sera between 12-h adjacency intervals were high, but those between longer times (48 or 60 h) were low. Simple correlations of serum constituents between cows and calves at birth were low except for BUN (r = .578 and .295 for yr 1 and 2, respectively). There were significant main treatment effects for maternal CP consumption on BUN levels, for environmental temperature on BUN, Creat, and TBil levels, and for years on BUN, Creat, iron, and AlkPhos levels in calves. Significant polynomial relationships were found over hours of age for all variables. Blood urea N decreased in normal calves but remained relatively constant at a low level in deficient calves. Year x hour of age interactions occurred for iron, TProt, AlkPhos, TBil, and Chol. Protein x year x hour of age interactions were found for iron and Chol. These results suggest that random sampling times are not useful for decision making during the first 72 h after birth. Consideration must be given to multiple samples taken at specific calf ages, to environmental temperatures, and to maternal protein nutritional levels when interpreting calf blood sera data.

Alkaline Phosphatase↗
PubMed1990

Social inequalities in self-reported morbidity: interpretation and comparison of data from Britain and France.

This paper considers the results from national surveys of self-reported morbidity in Britain and France and discusses the implications for our understanding of social class differences in the propensity to report illness. The methods adopted in these surveys in the two countries are so different that any comparison of the results must be limited. However, evidence on the trends over time in illness reporting in both countries reinforces the impression that the survey methodology has a significant impact on the results in terms of social class inequalities. The discussion also considers some other possible explanations for apparent changes in the propensity to report illness. It is concluded that in both countries the national survey data on class differences in self-reported morbidity has limitations and might be improved in the light of developments in survey methodology and the cross-fertilisation of ideas through international comparative studies of the subject.

Cross-Cultural Comparison↗
PubMed1989

Isolation, sequence, and expression in Escherichia coli of an unusual thioredoxin gene from the cyanobacterium Anabaena sp. strain PCC 7120.

Two sequences with homology to a thioredoxin oligonucleotide probe were detected by Southern blot analysis of Anabaena sp. strain PCC 7120 genomic DNA. One of the sequences was shown to code for a protein with 37% amino acid identity to thioredoxins from Escherichia coli and Anabaena sp. strain PCC 7119. This is in contrast to the usual 50% homology observed among most procaryotic thioredoxins. One gene was identified in a library and was subcloned into a pUC vector and used to transform E. coli strains lacking functional thioredoxin. The Anabaena strain 7120 thioredoxin gene did not complement the trxA mutation in E. coli. Transformed cells were not able to use methionine sulfoxide as a methionine source or support replication of T7 bacteriophage or the filamentous viruses M13 and f1. Sequence analysis of a 720-base-pair TaqI fragment indicated an open reading frame of 115 amino acids. The Anabaena strain 7120 thioredoxin gene was expressed in E. coli, and the protein was purified by assaying for protein disulfide reductase activity, using insulin as a substrate. The Anabaena strain 7120 thioredoxin exhibited the properties of a conventional thioredoxin. It is a small heat-stable redox protein and an efficient protein disulfide reductase. It is not a substrate for E. coli thioredoxin reductase. Chemically reduced Anabaena strain 7120 thioredoxin was able to serve as reducing agent for both E. coli and Anabaena strain 7119 ribonucleotide reductases, although with less efficiency than the homologous counterparts. The Anabaena strain 7120 thioredoxin cross-reacted with polyclonal antibodies to Anabaena strain 7119 thioredoxin. However, this unusual thioredoxin was not detected in extracts of Anabaena strain 7120, and its physiological function is unknown.

Amino Acid Sequence↗
PubMed1989

Passage to Patna.

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Child Health Services↗
PubMed1987

Home help provision to the elderly in France and England.

Home help is less generous in France than in England. The different systems of administration and operation of the service in the two countries are discussed. The analysis reported used survey data on elderly people over 65 years old living in private households, from samples of 1001 in the London region and 1324 in the Paris region of Ile de France. The data provided information on incapacity, disability for household tasks, support from members of the household, and home help use. The data on disability were used to distinguish in both samples different groups of elderly people needing home help according to alternative criteria. Two measures of efficiency of allocation of home help were used; targetting of the service on those in the need group, and coverage of those in the need group. The ratio of coverage/targetting indicated whether it would be possible to provide for all those in the need group by redistributing existing home help services. In both samples, especially in Paris, the home help service was distributed particularly in favour of lone elderly people with disability for household tasks. For some need groups, targetting seemed equally efficient in Paris as in London, however, the coverage of the parisian system was less comprehensive than in London, reflecting the low overall provision of the service. The implications for policy making and planning for the home help service in France are discussed.

Aged↗
PubMed1987

Characteristics of elderly people receiving home-help in three regions of France.

This study examined the allocation of home-help to the elderly using survey data collected on 3153 elderly respondents living at home in Haute-Normandie, Lille, and Ile-de-France. The samples of respondents were stratified by age, sex and area of residence, and were randomly selected from the electoral registers. The analysis identified 399 elderly people "in need": of home-help - living alone with disability. Of these, only 21% received home help. Of 174 home help recipients, 49% were "in need", and they received 52% of the volume (hours) of help allocated. The pattern of allocation varied regionally.

Aged↗
PubMed1987

[Study of the factors associated with the inability to perform household tasks among aged persons on the Ile-de-France. Application to the sub-regional planning of home-help services].

The aim of this paper is to present the preliminary results of a planning project in the area of health and social services for the elderly, which makes it possible to estimate the number of persons likely to seek help from such services at the administrative area levels with decisional powers. This involves identifying predictors of disability from raw data routinely available in the census and at various administrative area levels, the municipality being the preferred level. From the epidemiological data collected at the regional level, an indicator of disability has been constructed. Initially, those factors possibly associated with disabilities were identified by regrouping the variables in four dimensions (discriminant analysis): socio-economic, physical environment, human environment, local administrative area environment (district data from census, medical-social services offered in the area, ect.). Subsequently, a logistic regression made it feasible to calculate the coefficients attached to these predictors of disability. In our sample, sex, age and level of housing amenities in the dwelling place appear to be predictors of disability. The application of the coefficients obtained at the region level--by means of an epidemiological approach to distributions by sex, age and dwelling amenities characterizing a municipality or group of municipalities (territorial approach)--enabled us to estimate the number of persons 65 and over likely to seek help from home-assistance services at whatever administrative area level chosen. In certain of its quantitative aspects, this mixed approach (individual and area) helps in determining need, the first step in the planning process.

Activities of Daily Living↗
PubMed1986

Socio-demographic variation in perceived illness and the use of primary care: the value of community survey data for primary care service planning.

This paper addresses the question of the prevalence of self reported morbidity in the community and reports on results obtained using the Nottingham Health Profile in a population survey of morbidity. The variation between demographic and social groups and the relationship with GP are considered. The results show that certain aspects of morbidity vary according to social group more markedly than other aspects, and that some dimensions of self reported morbidity are predictive of recent consultation reported by the respondents. The interpretation of data of this sort for health planning purposes is considered. For example, the manual groups were particularly susceptible to tiredness and sleep disturbance, but these were not conditions associated with more frequent consultation. The manual groups also reported higher levels of pain and emotional distress, which were associated with propensity to consult. Other types of morbidity associated with consultation with the general practitioner were physical symptoms of pain and feelings of social isolation, but these did not show a strong class difference.

Adolescent↗
PubMed1984

Effects of estradiol and tamoxifen on human breast cancer cells in serum-free culture.

ZR-75-1 human mammary cancer cells can be grown in serum-free medium in an estradiol- and tamoxifen-sensitive manner. Growth occurs both in monolayer and suspension culture, although serum is necessary during the initial plating of the cells in monolayer culture. Optimal stimulation of proliferation by estradiol occurs at 10(-8) and 10(-9) M. Tamoxifen alone weakly stimulated growth in a dose-dependent manner up to 10(-7) M, but inhibition was observed at 10(-6) M. This inhibition was not seen if the cells were cultured in 10% dextran:charcoal-treated fetal calf serum. This difference is ascribed to tamoxifen binding components in the serum. In the absence of serum, tamoxifen (10(-6) M) abolished the proliferative effect of estradiol at all concentrations of estradiol below 10(-7) M. Higher concentrations of estradiol partially overcame the tamoxifen effect. Consistent antiestrogenic effects of tamoxifen required an estradiol:tamoxifen ratio of 1:1000.

Breast Neoplasms↗