Separated response function ratios in exclusive, forward π(±) electroproduction

The study of exclusive π(±) electroproduction on the nucleon, including separation of the various structure functions, is of interest for a number of reasons. The ratio RL=σL(π-)/σL(π+) is sensitive to isoscalar contamination to the dominant isovector pion exchange amplitude, which is the basis for the determination of the charged pion form factor from electroproduction data. A change in the value of RT=σT(π-)/σT(π+) from unity at small -t, to 1/4 at large -t, would suggest a transition from coupling to a (virtual) pion to coupling to individual quarks. Furthermore, the mentioned ratios may show an earlier approach to perturbative QCD than the individual cross sections. We have performed the first complete separation of the four unpolarized electromagnetic structure functions above the dominant resonances in forward, exclusive π(±) electroproduction on the deuteron at central Q(2) values of 0.6, 1.0, 1.6  GeV(2) at W=1.95  GeV, and Q(2)=2.45  GeV(2) at W=2.22  GeV. Here, we present the L and T cross sections, with emphasis on RL and RT, and compare them with theoretical calculations. Results for the separated ratio RL indicate dominance of the pion-pole diagram at low -t, while results for RT are consistent with a transition between pion knockout and quark knockout mechanisms.

British Dietetic Association evidence-based guidelines for the protein requirements of adults undergoing maintenance haemodialysis or peritoneal dialysis

BACKGROUND

Existing nutritional guidelines suggest that protein requirements of adults with stage five chronic kidney disease undergoing haemodialysis (HD) or peritoneal dialysis (PD) are increased as a result of protein losses during dialysis. The present review aimed to update previous guidance and develop evidence-based practice guidelines on the protein requirements of adults undergoing maintenance dialysis.

METHODS

Following a PICO approach (Participants or Population, Intervention or Exposure, Comparison and Outcome), four research questions were formulated to investigate the total protein requirement and protein quality required by adults undergoing HD and PD. A comprehensive, systematic review was undertaken using the databases Medline, EMBASE and the Cochrane Library from 2005 to September 2009 for HD studies and from 1997 to September 2009 for PD studies.

RESULTS

The literature search yielded 2931 studies, which were assessed for inclusion. Following appraisal, 19 studies in HD and 18 studies in PD met the inclusion criteria and were systematically reviewed. Limited good quality evidence supports the recommendations that: (i) adults undergoing maintenance HD require a minimum protein intake of 1.1 g kg(-1) ideal body weight (IBW) per day; and (ii) adults undergoing maintenance PD require a minimum protein intake of 1.0-1.2 kg(-1) IBW per day, in conjunction with an adequate energy intake. There were no studies that addressed the quality of protein for either HD or PD.

CONCLUSIONS

Evidence suggests that nutritional status may be maintained with lower protein intakes than previously recommended. However, the evidence base is limited and further randomised controlled trials are required to establish the optimal protein intake for dialysis patients.

The detection of malingering in memory performance: The sensitivity and specificity of four measures in a UK population

OBJECTIVES

To investigate the validity of a clinical neuropsychological battery for the detection of malingering on tests of memory.

METHODS

A simulated scenario design was developed to investigate the effectiveness of a battery of four neuropsychological tests in the detection of malingering; the Coin in the Hand Test (CIH), Autobiographical Memory Index (AMI), Rey I 5-Item Test (RIT),and the Wechsler Mental Control Test (MCT). The performances of patients with an acquired brain injury (N = 40) were compared with two groups of controls instructed either to simulate a head injury performance (N = 40) or do their best (N = 40).

RESULTS

The CIH and MCT demonstrated good validity and displayed high sensitivity and specificity. The RIT and the AMI was relatively poor in distinguishing between simulators and patients.

CONCLUSIONS

The sensitivity and specificity of all four tests to the detection of malingering has been assessed. Two of the tests the CIH and MCT would be useful as a quick and accurate screening tool for detecting malingering.

STUDIES OF DISEASES OF THE LYMPHOID AND MYELOID TISSUES. I : THE CHEMICAL METABOLISM OF NORMAL AND PATHOLOGICAL LYMPH NODES

From a study of the metabolism of 71 lymph nodes and tumors one may conclude: 1. The nature of a tumor can not be predicted from the metabolism because too much overlapping of metabolic rates exists between the pathological groups. 2. There is no evidence metabolically one way or another as to whether malignant lymphomata of any type should be classed as neoplastic or as infectious processes. 3. The degree of cell differentiation can in most cases be foretold by the percentage difference between the aerobic and the anaerobic glycolysis. The greater the differentiation the greater the percentage difference. Sarcomata in general constitute an exception to this rule. 4. The degree of malignancy in carcinoma, but not in other tumors, can, with certain exceptions, be predicted from the height of the value U. 5. Human sarcomata appear to have a metabolism far more closely comparable to that of benign tumors than to that of carcinomata. They do not behave as malignant tumors under the Warburg classification. Their energy requirements are not of the same order as those of carcinoma. 6. One can not from the value U or from the glycolytic rates predict whether or not a tissue should be classed as neoplastic. 7. Warburg's findings for carcinomata are confirmed and amplified.

Suicide attempt in first-episode psychosis: a 7.4 year follow-up study

BACKGROUND

Individuals with first-episode psychosis demonstrate high rates of suicide attempt (SA).

AIMS

1) To examine the prevalence of, and risk factors for, SA in a first-episode psychosis (FEP) cohort over a 7.4 year follow-up period. 2) To investigate differences between single versus multiple suicide attempters.

METHODS

This study reports baseline and follow-up data from a naturalistic, prospective follow-up of 413 FEP patients treated at a specialist early psychosis centre. Assessments were conducted at treatment entry, initial symptom remission or stabilization, and long term follow-up. Binary logistic regression models were used to assess unadjusted and adjusted associations between early illness and sociodemographic characteristics and two outcome measures: any SA during follow-up; and multiple SAs.

RESULTS

Follow-up data were available for 282 participants. Sixty-one (21.6%) made a suicide attempt over the follow-up period, including 12 successful suicides. The following baseline risk factors increased the risk of any SA: history of self-harm (OR=4.27; p<0.001), suicidal tendencies (OR=2.30; p=0.022), being depressed for >50% of the initial psychotic episode (OR=2.49; p=0.045), and hopelessness (OR=2.03; p=0.030). History of problem alcohol use increased the risk of multiple SAs (OR=4.43; 95% CI (1.05-18.7); p=0.043).

DISCUSSION

The prevalence of suicide attempt in this study exceeds reports from short-term FEP studies but is comparable to longer term follow-up studies, indicating that risk remains elevated for at least 7 years following commencement of treatment. The key predictor of future suicide attempt was previous self-harm, indicating that interventions for self-harm are required.

The role of interleukin 6 in megakaryocyte formation, megakaryocyte development and platelet production

Megakaryocytopoiesis is the cellular amplification and differentiation of precursors into immature megakaryocytes, and the cytoplasmic maturation of these megakaryocytes, a process terminating in the release of platelets into the circulation. Interleukin 6 (IL-6) stimulates megakaryocytopoiesis in the bone marrow, increasing platelet numbers in the circulation. IL-6 alone is poorly active on the growth of stem cell populations, but acts in synergy with stem cell factor (c-kit ligand) to expand the committed myeloid progenitor compartments but not the megakaryocyte progenitors. IL-6 has a direct action on megakaryocyte progenitors but only in synergy with low doses of interleukin 3 (IL-3), increasing the number of immature megakaryocytes and enhancing the processes of development into mature megakaryocytes. IL-6 is about 10 times more active on megakaryocytes than on megakaryocyte progenitors in cell culture. It is active alone and will stimulate increases in cell size and DNA content. IL-6 does not appear to stimulate the process of platelet release. IL-6 is found in bone marrow, in both macrophage subsets and megakaryocytes, indicating that it may be an important physiological regulator of both paracrinal (microenvironmental) and autocrinal mechanisms controlling megakaryocyte development in bone marrow.

Prevalence and correlates of comorbidity 8 years after a first psychotic episode

OBJECTIVE

While rates and correlates of comorbidity have been investigated in the early course of psychosis, little is known about comorbidity in the medium-to-longer term or its relationship with outcome.

METHOD

A total of 182 first-episode psychosis (FEP) patients who met DSM-IV criteria for a current psychotic disorder 8 years after index presentation were grouped according to concurrent comorbidity [no concurrent axis I disorder; concurrent substance use disorder (SUD); other concurrent axis I disorder; concurrent SUD and other axis I disorder]. Outcomes were compared between groups controlling for relevant covariates.

RESULTS

As much as 39% met criteria for one or more concurrent axis 1 diagnoses. Comorbidity was associated with greater severity of general psychopathology, but not with measures of functioning, treatment or negative symptoms.

CONCLUSION

Specific combinations of comorbid disorders may influence patterns of psychotic symptomatology. Routine examination of axis I disorders is warranted in the ongoing management of psychosis.

Does lesion size determine the success rate of photodynamic therapy for age-related macular degeneration?

Photodynamic therapy (PDT) is a new evidence-based treatment modality available for choroidal neovascularisation (CNV) secondary to age-related macular degeneration (AMD). Eligibility for PDT is based on the morphological classification of the neovascular complex, the benefit being greater in classic with no occult lesions. Lesion size is also shown to be a predictive factor for treatment benefit. This retrospective case series looked at effect of initial and final lesion size on the visual outcome of patients with subfoveal classic with no occult CNV and found that increasing initial and final lesion size is associated with poorer visual outcome.