Biofeedback treatment of atopic dermatitis: controlled case studies of eight cases.

To investigate the feasibility of a behaviorally oriented intervention program with atopic dermatitis, 12 patients were exposed to a fixed sequence of treatment phases including a no-treatment baseline phase, a phase incorporating nonspecific treatment factors, and a phase involving frontal electromyographic (EMG) feedback and relaxation instructions. Photographic analyses of involved skin areas revealed significant remission of dermatological problems across the entire program, although significant changes could not be attributable to any specific phase. Ratings of itching level decreased within but not across treatment sessions, and variable correlations across subjects were found between frontal EMG and itching level. MMPI results from the dermatitis subjects were within normal limits. Overall, the results provided mixed support for the hypothesis that atopic dermatitis may be amenable to intervention through behaviorally oriented treatment procedures.     

Mechanism of carbamoyl-phosphate synthetase. Properties of the two binding sites for ATP.

Carbamoyl phosphate synthethase I synthesizes carbamoyl phosphate from ammonia, HCO3- and two molecules of ATP, one of which, ATPA, yields Pi while the other, ATPB, yields the phosphoryl group of carbamoyl phosphate. Pulse-chase experiments with [gamma-32P]ATP without added HCO3- demonstrate separate binding sites for ATPA and ATPB. Bound ATPA dissociates readily from its site (t1/2 approximately 1--2 s) and the Kd is 0.2--0.7 mM. For the ATPB binding site the t1/2 for dissociation is 5--12 s and the Kd approximately 10 mM. Kd for ATPA seems to increase with enzyme concentration whereas Kd for ATPB does not change. HClO4 releases the ATP unchanged from the enzyme . ATPB and enzyme . ATPB . ATPA complexes. In the presence of HCO3-, ATP and N-acetylglutamate, an enzyme . ATPB . HCO3- . ATPA complex is formed. Its formation by the addition of HCO3- to the enzyme . ATPB . ATPA complex appears to involve an initial bimolecular addition reaction followed by an isomerization. Treatment with HClO4 releases Pi from ATPA but ATPB is released unchanged. Spontaneous hydrolysis of ATPA is responsible for the ATPase activity of the enzyme. Thus, a covalent bond may form between HCO3- and ATPA. However, ATPA can dissociate rapidly (t1/2 less than 10 s). The Kd for ATPA is approximately 0.2 mM. ATPB appears unable to dissociate from the enzyme . ATPB . HCO3- . ATPA complex since the t1/2 for dissociation of ATPB from the enzyme is lengthened about five times in the presence of 19 mM HCO3- and at 1 mM ATP. ATPA may also hydrolyse in this complex and be replaced by another molecule of ATP in the absence of exchange of ATPB. However, the ATPA binding site must be occupied to prevent ATPB release. ATPB may be bound in a pocket which becomes inaccessible to the solution when HCO3- and ATPA also bind. In contrast, HCO3- does not inhibit the binding of ATPB to the enzyme. Various intermediate steps in the formation of the enzyme . ATPb . HCO3- . ATPA complex are discussed. Additional evidence is presented that the ATPB binding site is only periodically accessible to ATP in solution and that ATPB in the steady-state reaction binds when the products leave. Since greater than 1.3 mol ATPB and greater than 1.8 mol ATPA bind/mol enzyme dimer, the enzyme monomer may be an active species.     

Development and evaluation of evidence based risk assessment tool (STRATIFY) to predict which elderly inpatients will fall: case-control and cohort studies.

OBJECTIVES: To identify clinical characteristics of elderly inpatients that predict their chance of falling (phase 1) and to use these characteristics to derive a risk assessment tool and to evaluate its power in predicting falls (phases 2 and 3). DESIGN: Phase 1: a prospective case-control study. Phases 2 and 3: prospective evaluations of the derived risk assessment tool in predicting falls in two cohorts. SETTING: Elderly care units of St Thomas''s Hospital (phase 1 and 2) and Kent and Canterbury Hospital (phase 3). SUBJECTS: Elderly hospital inpatients (aged > or = 65 years): 116 cases and 116 controls in phase 1,217 patients in phase 2, and 331 in phase 3. MAIN OUTCOME MEASURES: 21 separate clinical characteristics were assessed in phase 1, including the abbreviated mental test score, modified Barthel index, a transfer and mobility score obtained by combining the transfer and mobility sections of the Barthel index, and several nursing judgements. RESULTS: In phase 1 five factors were independently associated with a higher risk of falls: fall as a presenting complaint (odds ratio 4.64 (95% confidence interval 2.59 to 8.33); a transfer and mobility score of 3 or 4 (2.10 (1.22 to 3.61)); and primary nurses'' judgment that a patient was agitated (20.9 (9.62 to 45.62)), needed frequent toileting (2.48 (1.08 to 5.70)), and was visually impaired (3.56 (1.26 to 10.05)). A risk assessment score (range 0-5) was derived by scoring one point for each of these five factors. In phases 2 and 3 a risk assessment score > 2 was used to define high risk: the sensitivity and specificity of the score to predict falls during the following week was 93% and 88% respectively in phase 2 and 92% and 68% respectively in phase 3. CONCLUSION: This simple risk assessment tool predicted with clinically useful sensitivity and specificity a high percentage of falls among elderly hospital inpatients.     

Threshold, wave and cell-cell avalanche behaviour in a class of substrate inhibition oscillators.

Two molecules of IgG need to be in close proximity upon a cell surface in order to bind complement. Here we obtain approximate results for the probability that two or more IgG molecules are closer than some minimum separation distance, given that N IgG molecules are bound to the cell. Determining this probability exactly is a classical unsolved problem in geometrical probability. We also estimate the probability of having n pairs of IgG molecules in close proximity and compute the expected number of IgG pairs. Our theoretical results are compared with experimental measurements on complement fixation by IgG.     

AN IN VIVO STATHMOKINETIC STUDY OF CELL PROLIFERATION IN HUMAN GASTRIC CARCINOMA AND GASTRIC MUCOSA

Cell production rates were studied in a group of eleven patients with carcinoma of the stomach using an in vivo technique with vincristine. In normal pyloric mucosa estimates ranged from 8 to 15 cells/1000 cells/hr, and in the carcinomas from 3 to 24 cells/1000 cells/hr. Because of the very large variation in the data, comparison between individual tumours and normal mucosa is not regarded as being worth while at this stage. The implications of these results for previous human in vivo stathmokinetic experiments are also discussed.     

Cross-conjugated carotenoid aldehydes in Rhodopseudomonas viridis

Two carotenoid aldehydes isolated from Rhodopseudomonas viridis (Rhodospirillaceae) have been identified as lycopen-20-al (13-cis-ψ, ψ-caroten-20-al) and the novel 3,4-didehydro-1,2-dihydrolycopen-20 (or 20′)-al (3,4-didehydro-1,2-dihydro-ψ,ψ-caroten-20-al or 3′, 4′-didehydro-1′,2′-dihydro-ψ,ψ-caroten-20-al). Some extracts also contained acetonyl derivatives, probably artefacts produced from the cross-conjugated carotenoid aldehydes and acetone under alkaline conditions. The distribution of cross-conjugated caroten-20-als in photosynthetic bacteria is discussed.     

Prognosis of angina with and without a diagnosis: 11 year follow up in the Whitehall II prospective cohort study

Objective To investigate the prognosis of angina among people with and without diagnosis by a doctor and an abnormal cardiovascular test result.Design Prospective cohort study with a median follow up of 11 years.Setting 20 civil service departments originally located in London.Participants 10 308 civil servants aged 35-55 years at baseline.Main outcome measures Recurrent reports of angina; quality of life (SF-36 physical functioning); non-fatal myocardial infarction; death from any cause (n = 344).Results 1158 (11.4%) participants developed angina, and 813 (70%) had no evidence of diagnosis by a doctor at the time of the initial report. Participants without a diagnosis had an increased risk of impaired physical functioning (age and sex adjusted odds ratio of 2.36 (95% confidence interval 1.91 to 2.90)) compared with those who had neither angina nor myocardial infarction throughout follow up. Among reported cases of angina without a diagnosis, the 15.5% with an abnormality on a study electrocardiogram had an increased risk of death (hazard ratio 2.37 (1.16 to 4.87)). These effects were similar in magnitude to those in participants with a diagnosis of angina.Conclusion Undiagnosed angina was common and had an adverse impact on prognosis comparable to that of diagnosed angina, particularly among people with electrocardiographic abnormalities. Efforts to improve prognosis among people with angina should take account of this submerged clinical iceberg.     

Habitat fragmentation,percolation theory and the conservation of a keystone species

Many species survive in specialized habitats. When these habitats are destroyed or fragmented the threat of extinction looms. In this paper, we use percolation theory to consider how an environment may fragment. We then develop a stochastic, spatially explicit, individual-based model to consider the effect of habitat fragmentation on a keystone species (the army ant Eciton burchelli) in a neo tropical rainforest. The results suggest that species may become extinct even in huge reserves before their habitat is fully fragmented; this has important implications for conservation. We show that sustainable forest-harvesting strategies may not be as successful as is currently thought. We also suggest that habitat corridors, once thought of as the saviour for fragmented environments, may have a detrimental effect on population persistence.