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Biomedical subjects

D Barnes

Publications and source records attributed to D Barnes.

At least 73 records · Page 4Linked to original sources
PubMed1997

Spinal rigidity following acute myelitis.

A patient with a 2(1/2)-year history of painful spasms and rigidity of both lower limbs is described. Symptoms began after an episode of acute myelitis. The spasms--which were spontaneous and stimulus sensitive and occurred on voluntary action--involved the repetitive grouped discharge of motor units. Continuous motor unit activity was present at rest in the muscles of both legs, and cutaneomuscular reflexes were abnormal. This patient is similar to those recently reported as having stiffness and spasms of the legs due to a possible chronic spinal interneuronitis and provides further evidence that this kind of movement disorder may be caused by spinal cord pathology.

Acute Disease↗
PubMed1997

Emergent conditional discriminations in children and adults: stimulus equivalence derived from simple discriminations.

This study examines whether trained and derived simple discriminations lead to conditional relations between discriminative stimuli of the same and opposite (S+, S-) functions. After being trained on an arbitrary X-Y task (X1-Y1, X2-Y2) and on two simple discrimination tasks (A1+/A2- and B1+/B2-), children (Experiment 1) and adults (Experiment 2) were tested on the formation of novel simple discriminations (A3+/A2- and B3+/B2-) and conditional stimulus relations between all directly and indirectly paired A stimuli and between all directly and indirectly paired B stimuli (A1-A2-A3, B1-B2-B3). Subjects who formed these sets also received A2-X1 and B1-X2 training followed by a series of probes to assess the formation of two five-member stimulus equivalence classes (A1-A2-A3-X1-Y1, B1-B2-B3-X2-Y2). A modest majority of the children matched the directly paired stimuli (A2-A1, B2-B1 and A1-A2, B1-B2; A2-A3, B2-B3 and A3-A2, B3-B2) with one another while only a few of them also matched the indirectly paired stimuli with one another (A1-A3, B1-B3 and A3-A1, B3-B1). Those who did also related all the A and B stimuli with the designated X and Y stimuli. By contrast, all normal adults matched all paired and conditionally linked stimuli with one another. Present findings and those of related studies on stimulus equivalence are discussed from a stimulus contiguity perspective.

Age Factors↗
PubMed1997

Functional equivalence in children: derived stimulus-response and stimulus-stimulus relations.

The present study investigated the simultaneous occurrence of emergent stimulus-response relations (functional equivalence) and stimulus-stimulus relations (stimulus equivalence). After being pretrained and tested on two symbolic match-to-sample tasks (X1-Y1, X2-Y2), 20 4- and 5-year-old children were trained to emit specified responses to pairs of stimuli (A1-R1, B1-R1, A2-R2, B2-R2) in one setting (original training) and to emit other responses to one member of each pair (A1-R3, A2-R4) in another setting (reassignment training). Of the 18 children who responded correctly on all trained tasks, 15 emitted the novel responses also in the presence of the nonreassigned stimuli (B1-R3, B2-R4). Eleven of these children also matched same-class stimuli with one another (A1-B1, A2-B2, and vice versa). Additional tests with four of these children documented the formation of conditional response-stimulus relations (R3-B1, R4-B2) in all four children, and of conditional response-response relations (R1-R3, R2-R4, and vice versa) in two of them. Children who did not show stimulus control transfer also failed to match same-class stimuli with one another. Present findings, together with those obtained in animal research, suggest that functional equivalence can imply but does not require stimulus equivalence.

Child, Preschool↗
PubMed1997

Effect of dietary dl-alpha-tocopherol on tissue alpha- and gamma-tocopherol and pulmonary hypertension syndrome (ascites) in broilers.

The objectives of this experiment were to determine the effects of high dietary levels of vitamin E on growth performance and pulmonary hypertension syndrome (PHS) mortality. Male broiler chicks (Cobb 500) were randomly assigned to one of four dietary treatments consisting of standard starter and grower diets supplemented with 0, 17, 46, and 87 mg dl-alpha-tocopherol acetate/kg. To encourage the development of PHS, air temperature in the house was 32 and 28 C for Weeks 1 and 2, dropped to 18 C during Week 3, and kept between 10 and 15 C during Weeks 4 through 7. Also, chicks were placed in floor pens on litter used for five previous flocks and ventilation reduced to increase dust and ammonia in the house. Ammonia levels increased from an initial 18 to 36 ppm on Day 42 with the increase in ammonia corresponding to an obvious increase in dust in the air. Lung and liver tissue obtained at 2, 5, and 7 wk of age were analyzed for tissue alpha- and gamma-tocopherol by liquid chromatography. Dietary vitamin E had no effect on body weight, feed intake, or feed efficiency. Cumulative PHS mortality through 7 wk of age was 21% and was also unaffected by dietary treatment. Liver and lung alpha-tocopherol concentrations exhibited a dose-response increase to dietary tocopherol and there was a high correlation between lung and liver tissue alpha-tocopherol (r = 0.72, P < 0.05). Whereas gamma-tocopherol concentrations in lung and liver were unaffected by dietary treatment, liver and lung exhibited age-dependent increases in both alpha- and gamma-tocopherol. Despite dose-dependent increases in tissue alpha-tocopherol, supplementation of diets with up to 87 mg dl-alpha-tocopherol acetate had no effect on growth performance or PHS mortality in broilers under the conditions used in this study.

Ammonia↗
PubMed1997

Characterization of dynamic 3-D PET imaging for functional brain mapping.

Methods for optimizing the acquisition, reconstruction and analysis of positron emission tomography (PET) images for functional brain mapping have been investigated. The scatter fraction and noise-equivalent count rate characteristics were measured for the ECAT 951/31R PET scanner operating in septa-extended two-dimensional (2-D) and septa-retracted three-dimensional (3-D) modes. The 3-D mode is shown to provide higher signal-to-noise images than the 2-D mode at specific activities less than 30 kBq/ml. To enable increased temporal resolution in dynamic 3-D PET activation studies, a parallel version of the 3-D reconstruction algorithm was developed. Implementation of the reprojection algorithm on an 88 processor 1860 supercomputer resulted in a more than tenfold increase in reconstruction speed compared to a single 1860 processor system. An investigation of the optimal duration for imaging brain activations was undertaken in 12 normal subjects using repeated H2(15)O slow infusions and a visually presented lexical decision task. The significance of change in regional cerebral blood flow (CBF) was determined using statistical parametric maps for images acquired during stimulation, immediately after stimulation, and commencing 1 min after cessation of the stimulus. Regions of CBF change were detected in all three images. Dynamic 3-D, or four-dimensional (4-D), PET activation scanning is shown to be practical and likely to further improve the sensitivity of PET for detection of subtle regional CBF changes in functional brain mapping research.

Adult↗
PubMed1997

Studies to assess if pizotifen prophylaxis improves migraine beyond the benefit offered by acute sumatriptan therapy alone.

Two multi-centre studies-one double-blind, placebo-controlled (study 1) and one open (study 2)-were set up to assess if pizotifen prophylaxis improved migraine beyond the benefit offered by acute sumatriptan therapy alone. Eighty-eight patients completed the blinded study and 63 patients completed the open study. Both studies were of crossover design with patients undertaking a 4 week run-in period prior to a 12-week treatment period. Following a 4-week washout period patients commenced a second 12-week treatment period on the alternative treatment regimen. All breakthrough attacks were treated with 100 mg oral sumatriptan with an optional 2 doses available to treat any recurrence within 24 h of taking dose 1. Pizotifen was built up to a final daily dose of 1.5 mg over a 2-week period and patients remained on this dose for a further 10 weeks. Patients in the blinded study were given matching placebo tablets for one of the two treatment periods. The efficacy of sumatriptan was not affected by pizotifen. The median of the monthly attack rate experienced by patients was slightly lower whilst patients were on pizotifen and sumatriptan than while on placebo prophylaxis and sumatriptan or sumatriptan alone; study 1, 3.5 vs 3.9 attacks per month (p = 0.008); study 2, 2.9 vs. 3.2 attacks per month (p = 0.23). Also, while on pizotifen and sumatriptan more patients had a greater proportion of their time in the study migraine-free. From the results of these studies it does not appear that pizotifen reduces migraine severity; regardless of the treatment regimen the initial headache severity of most attacks was moderate. Weight gains experienced by patients while on pizotifen and sumatriptan were greater than the weight gains experienced while on placebo prophylaxis and sumatriptan or sumatriptan alone (period 1); study 1, 2.6 vs. 1.0 kg (p = 0.002); study 2, 1.6 vs. -0.8 kg (p < 0.0001). The combination of pizotifen and sumatriptan did not result in any additional adverse events other than those usually seen with each medication alone. In these studies, where the average number of migraine attacks was around 4 per month, the benefits conferred by pizotifen were at the expense of the adverse events associated with the drug, particularly weight gain. Therefore the clinical benefit of treatment with pizotifen for patients who have less than 4 attacks per month should be carefully reviewed as acute treatment with sumatriptan may be the most appropriate treatment. Pizotifen may be better reserved for those patients who have 4 of more attacks per month.

Adolescent↗
PubMed1997

An investigation into the temperature dependence of the rheological synergy between xanthan gum and locust bean gum mixtures.

The interaction between xanthan gum (XG) and locust bean gum (LBG) in water has been investigated using texture analysis, thermorheological analysis and high sensitivity differential scanning calorimetry. For the batches of XG and LBG used in the present study and at a total polymer concentration of 1% w/v, texture analysis indicated that the greatest synergy occurred at approximately 10% w/w XG, while the technique also allowed measurement of the increase in strength resulting from heating the mixes to 70 and 80 degrees C and cooling to room temperature. Thermorheological studies showed a maximum in viscosity for the xanthan gum gels at approximately 45 degrees C; this maximum became less pronounced as the concentration of XG decreased. High sensitivity differential scanning calorimetry indicated that XG undergoes two transitions at approximately 30 and 80 degrees C on heating, but on cycling a single transition is seen at approximately 74 degrees C. It was also noted that the transitions were diminished or were absent in the presence of LBG.

Calorimetry, Differential Scanning↗
PubMed1997

A transformation of respondently conditioned stimulus function in accordance with arbitrarily applicable relations.

Adult male subjects saw a sexual film clip paired with a nonsense syllable (C1). Similarly, an emotionally neutral film clip was paired with a second nonsense syllable (C3). Responses to the nonsense syllables were recorded as skin resistance responses. Subjects were also trained in a series of related conditional discriminations, using the C1 and C3 stimuli, from which the following equivalence relations were predicted; A1-B1-C1, A2-B2-C2, and A3-B3-C3. Some subjects were given matching-to-sample (equivalence) tests after the conditional discrimination training (Experiment 1), whereas others were not (Experiment 2). Subjects were tested for a transformation of eliciting functions by presenting the A1 and A3 stimuli, which were related through equivalence to C1 and C3, respectively. Five of the 6 subjects who showed significantly greater conditioned responses to C1 than to C3, also showed significantly greater skin resistance responses to A1 than to A3. Two additional subjects demonstrated a transformation of an eliciting stimulus function in accordance with five-member equivalence relations (Experiment 3), and another 5 subjects demonstrated similar effects in accordance with the relations of sameness and opposition (Experiment 4).

Adolescent↗
PubMed1997

Cloning, sequencing, and embryonic expression of an N-ras proto-oncogene isolated from an enriched zebrafish (Danio rerio) cDNA library.

An enriched zebrafish (Danio rerio) complementary DNA library was constructed for screening of ras-related genes, and a positive clone was isolated from one plate of 3 x 10(4) plaques. This clone, Zras-B1, carried an insert of 2592 base pairs (bp) with an open reading frame encoding a ras p21 protein of 188 amino acids. The deduced amino-terminal 86 amino acid residues and the carboxy-terminal CAAX binding motif are identical to mammalian ras. The full-length Zras-B1-encoded protein is most closely related to human N-ras (91% identity), with lesser homology to Ha-ras (84%) and Ki-ras (85%). Preliminary screening data also indicate other ras genes in zebrafish, at least one of which is also transcribed in adults. A Zras-B1-related 3.1-kb transcript was found to be abundant in embryos from zygote through gastrulation, and may be maternally derived.

Amino Acid Sequence↗
PubMed1996

Cyclin D1 and prognosis in human breast cancer.

We have used immunohistochemical staining to assess the expression of cyclin D1 in formalin-fixed sections of 345 breast carcinomas, dating back 20 years. Clinical follow-up data were available on all patients. Approximately 50% of the tumours showed excessive nuclear staining for cyclin D1 as compared with normal epithelium. Some tumours showed strong cytoplasmic staining in the absence of nuclear staining, and around 25% of the tumours were judged to be negative for nuclear cyclin D1. Contrary to expectations, moderate/strong staining for cyclin D1 was associated with improved relapse-free and overall survival relative to patients whose tumours stained weakly or negatively. Conversely, tumours that were considered negative for cyclin D1 staining had an adverse prognosis, and the poor outcome was further accentuated if the tumours were also oestrogen receptor-negative. A possible explanation for our findings is that tumours in which cyclin D1 levels are abnormally low may have sustained mutations in other genes, such as RBI and that it is this abnormality that has the more significant impact on survival from breast cancer.

Adult↗
PubMed1996

Patterns of disease activity in multiple sclerosis patients: a study with quantitative gadolinium-enhanced brain MRI and cytokine measurement in different clinical subgroups.

In this study we assessed the subclinical disease activity in 45 patients with primary progressive, secondary progressive or relapsing-remitting multiple sclerosis (MS). The patients had gadolinium-enhanced brain MRI scans, which were analysed using a semiquantitative method both for lesion load and for degree of enhancement. At the same time cerebrospinal fluid (CSF) and serum samples were collected and, from these, cytokine levels were measured in most cases by enzyme-linked immunoassay using commercially available kits. Enhancing lesions on MRI were found in 73% of the patients. The sensitivity of this test was greatly increased by our method of analysis as far as the primary progressive patients are concerned (70% vs 40% for conventional evaluation). CSF interleukin-1 beta (IL-1 beta) levels were above the normal range in 22% and IL-6 levels in 13% of patients, while tumour necrosis factor alpha (TNF-alpha) was undetectable or below the upper normal limits in all the samples tested. Serum IL-1 beta was above the normal limits in 40%, IL-6 in 42% and TNF-alpha in 7% of patients. No significant differences in cytokine profiles were found between the clinical subgroups. This study confirms the high sensitivity of gadolinium-enhanced MRI in detecting MS activity, which was further increased by our method of analysis. Longitudinal studies performed with more sensitive immunological techniques are needed to define better the relationship between cytokine, clinical and MRI data in MS patients.

Adult↗
PubMed1996

Microalbuminuria as a marker of silent myocardial ischaemia in IDDM patients.

Insulin-dependent diabetic (IDDM) subjects with microalbuminuria have an increased long-term risk of overt cardiovascular disease; however, the early exposure to cardiovascular risk factors may increase their predisposition to current silent myocardial ischaemia. The frequency of silent myocardial ischaemia detected by stress echocardiography and electrocardiography was significantly greater in 32 asymptomatic IDDM patients with microalbuminuria compared to 32 normoalbuminuric IDDM patients (25% [n = 8] vs 6.3% [n = 2]; p = 0.03, odds ratio [95% CI] 6.3 [1.2, 37.8]). Elective coronary artery bypass grafting was required in 1 patient with microalbuminuria and silent myocardial disease. Microalbuminuria and poorer autonomic function were independently associated with silent myocardial ischaemia in multivariate analysis (p = 0.03 and p = 0.02, respectively). Screening for silent myocardial ischaemia using these non-invasive tests may be warranted in microalbuminuric IDDM which patients could be of considerable clinical importance.

Adolescent↗
PubMed1996

Emergent simple discriminations and conditional relations in children, intellectually impaired adults, and normal adults.

Previous research has shown that when, under non-reinforced conditions, stimuli are added to S+ and S- stimuli in simultaneous discrimination tasks, transfer between paired stimuli is likely to occur. The present study examined whether this procedure also leads to the formation of conditional relations between paired stimuli. In Experiments 1, 2, and 3, normal pre-school children were trained on a simultaneous discrimination task with A1 reinforced and A2 not reinforced (A1+/A2-). Then they received two tests (no programmed consequences): one with B stimuli superimposed on the A stimuli (A1B1/ A2B2), and one with B stimuli only (B1/B2). Subjects who selected A1B1 and B1 also received conditional discrimination tests: one with B1 or B2 as samples and A1 and A2 as comparisons (B-A), and one in which the functions of these stimuli were reversed (A-B). Intellectually impaired adults and normal adults served in Experiments 4 and 5, respectively. These experiments were basically the same except that the subjects were also given the opportunity to demonstrate transfer from B to C via BC (B1C1/B2C2 and C1/C2 tests). Most children (75%) and intellectually impaired adults (75%) treated the conditional discrimination probe tasks as simple discriminations and typically selected the trained and derived S+ stimuli. The remaining children, intellectually impaired adults, and all normal adults related all directly and indirectly linked stimuli of the same functions conditionally to one another (A-B, B-C, A-C, and vice versa). The present findings suggest that, as humans develop, conditional stimulus relations may emerge from tasks and stimulus configurations that are increasingly remote from traditional conditional discrimination tasks.

Adult↗
PubMed1996

International population and development: the United Nations' Cairo Action Plan for women's health.

The report of the International Conference on Population and Development (Cairo Action Document) was sponsored by 180 national governments and 1,200 nongovernmental organizations during the United Nations' conference on women, population, and development in Cairo, Egypt 1994. Many international conferences preceded the one in Cairo but it was there that women participated at an unprecedented level in shaping the debate. The resulting document represents a quantum leap for women's health. Nurses can play a major role in using the principles in the Cairo Action Document by empowering women and enhancing their health care. To invite dialogue, the authors provide an analysis of the Cairo Plan from a nursing perspective and identify three paradoxes that may hinder progress: Universal values and local cultures, global policy and local implementation, and national development and women's empowerment. Clinicians, scholars, and members of professional organizations are asked to consider the assumptions that underlie the recommendations for action and to propose ways to resolve the problems that may evolve during implementation.

Egypt↗
PubMed1996

IFNB in MS.

Explore the source record for details and available documents.

Humans↗
PubMed1995

Amplification of chromosome band 11q13 and a role for cyclin D1 in human breast cancer.

In this paper we describe how research on the mouse mammary tumor virus model of breast cancer resulted in the identification of an amplified region of DNA on human chromosome 11 band q13. This amplification occurs in approximately 15% of primary breast cancers. Several candidate oncogenes map within the amplicon but by analysing expression of these genes a strong case can be made for a role for cyclin D1 in tumorigenesis. Immunohistochemical staining indicates that cyclin D1 is expressed at elevated levels in around 40% of breast cancers, including those with the 11q13 amplification. The potential function of cyclin D1 as a regulator of early cell division cycle events would be consistent with a role in neoplasia.

Blotting, Southern↗