What makes a high quality clinical research paper?

The quality of a research paper depends primarily on the quality of the research study it reports. However, there is also much that authors can do to maximise the clarity and usefulness of their papers. Journals' instructions for authors often focus on the format, style, and length of articles but do not always emphasise the need to clearly explain the work's science and ethics: so this review reminds researchers that transparency is important too. The research question should be stated clearly, along with an explanation of where it came from and why it is important. The study methods must be reported fully and, where appropriate, in line with an evidence based reporting guideline such as the CONSORT statement for randomised controlled trials. If the study was a trial the paper should state where and when the study was registered and state its registration identifier. Finally, any relevant conflicts of interest should be declared.

Intensified treatment of type 2 diabetes--positive effects on blood pressure, but not glycaemic control.

BACKGROUND: Since publication of the UK Prospective Diabetes Study (UKPDS) in 1998, there has been a clear evidence base for tight glycaemic (HBA(1c) < 7.0%) and blood pressure (BP < 140/85 mmHg) control. AIM: To determine the effect of UKPDS-based intensified glycaemic and BP targets on the care of type 2 diabetic patients attending a routine diabetes clinic. DESIGN: Two surveys, each of 500 consecutively attending type 2 diabetic patients. METHODS: The first survey was in a 3-month period in 1999, shortly after publication of the UKPDS study. The second was identical, but 2 years later. Glycaemic control (by DCCT-aligned HBA(1c)), BP and treatment details were recorded in both. RESULTS: BP control was significantly improved in the second survey (mean +/- SD systolic BP from 151 +/- 25 to 146 +/- 26 mmHg, p = 0.001; diastolic from 77 +/- 13 to 72 +/- 12 mmHg, p < 0.0001) and the proportion of patients on anti-hypertensive treatment increased from 33% to 60% (p < 0.0001). Mean HbA(1c) however remained unchanged (8.7 +/- 1.8% in 1999 vs. 8.5 +/- 1.8% in 2001), although there was evidence of more intensive treatment patterns, with declining numbers on diet alone and more on oral agents and/or insulin. DISCUSSION: Intensified BP control may be achievable within the confines of routine diabetes care, but achievement of optimal glycaemic targets remains problematic.

Elderly people with hypothalamic-pituitary disease and untreated GH deficiency: clinical outcome, body composition, lipid profiles and quality of life after 2 years compared to controls.

OBJECTIVE: Elderly patients with GH deficiency (GHD) have significant impairments in multiple aspects of quality of life (QOL) but similar lipid profiles compared to age-matched control subjects. There are, however, no data on changes in these parameters with time. This study assessed the impact of untreated GHD over a period of 2 years in a group of elderly patients with hypothalamic-pituitary disease in relation to new illnesses and differences in body composition, circulating lipid profile levels and QOL. Control subjects were also followed for 2 years. SUBJECTS: Twenty-seven elderly patients (> 65 years) with hypothalamic-pituitary disorders and GHD (mean peak stimulated GH response 1.6 mIU/l, range 0.6--5.0) were studied initially. Two years later 21 (13 males) agreed to attend for reassessment. Mean age was then 72.7 +/- 5.04 years (range 67--85). Eighteen patients had pituitary tumours, three had craniopharyngiomas. Twenty-seven control subjects were studied at baseline and 17 (7 males) agreed to attend for reassessment. Mean age was then 75.9 +/- 6.97 years (range 67--88). METHODS: Weight, body mass index (BMI), total fat mass (FM) (bioelectrical impedance), serum IGF-1 and fasting lipid profile (total cholesterol, triglyceride, HDL cholesterol, LDL cholesterol) were measured. QOL was assessed in both groups using five interviewer-administered self-rating questionnaires: the Nottingham Health Profile, Short Form-36, Hospital Anxiety and Depression Scale, Mental Fatigue Questionnaire and Life Fulfillment Scale. The GHD group also completed the Disease Impact Scale. RESULTS: Two of the 27 patients with GHD died during the 2-year follow-up (myocardial infarction and probable cerebrovascular accident). Four controls could not be traced but there were no deaths in the other 23. In the 21 GHD patients after 2 years, mean serum IGF-1 and BMI were unchanged (12.6 +/- 5.8 vs. 13.3 +/- 5.1 nmol/l, P = 0.5 and 28.3 +/- 4.3 vs. 29.1 +/- 4.2, P = 0.5, respectively) at the 2-year follow-up and there were no significant changes in the lipid profiles. However, there was a significant reduction in fat mass (31.7 +/- 11.2 vs. 28.5 +/- 10.9%, P = 0.04). In the 17 control subjects after 2 years, serum IGF-1 levels (17.2 +/- 4.0 vs. 15.7 +/- 5.6 nmol/l, P = 0.4), BMI and fat mass were unchanged. However, there was a significant fall in total cholesterol levels over the 2-year follow-up (6.3 +/- 0.9 vs. 5.7 +/- 0.9 mmol/l, P < 0.0001), although LDL cholesterol, triglycerides and HDL cholesterol were unchanged. Analysing the QOL data, the GHD patients had less energy (P < 0.05), more depression (P < 0.05), more pain (P < 0.05) and lower life fulfillment scores (P < 0.01) after 2 years. However, the control subjects also had less energy (P < 0.05), less vitality (P < 0.05) and lower self-esteem (P < 0.05), more depression (P < 0.05), worse mental health (P < 0.05), life fulfillment personal (P < 0.01), life fulfillment material (P < 0.02), physical functioning and role physical functioning (P < 0.05) after 2 years. Comparing the patients and controls at baseline, there were significant differences in IGF-1, BMI, FM, LDL cholesterol, personal life fulfillment, mental fatigue, general health and mental health. However, after 2 years, only BMI and depression scores were significantly different. CONCLUSION: These patients with untreated GHD did not have deterioration of body composition or lipid profiles when reassessed after a period of 2 years. In fact, fat mass fell. The control subjects did have a significant decrease in total cholesterol but no change in other lipids or body composition. Some quality of life domains did deteriorate in the patients with GHD. However, the control subjects also had worse quality of life scores after 2 years which were then little different from the GHD patients. These results raise doubts about the benefits of GH replacement in elderly people with GHD.

cAMP signaling can antagonize potent glucocorticoid post-transcriptional inhibition of stanniocalcin gene expression.

Stanniocalcin (STC) is a glycoprotein hormone first discovered in fish as a homeostatic regulator of calcium and phosphate transport; it has recently been discovered in mammals, in which it appears to have a similar role. It has also been implicated in a number of different physiological processes through correlative studies, but the factors regulating its production have not been elucidated. In this report, we show that steady-state STC mRNA levels in the mouse corticotrope tumor line, AtT-20, were exquisitely sensitive to glucocorticoids. Hydrocortisone and dexamethasone (Dex) induced a dramatic reduction in steady-state STC mRNA levels in AtT-20 cells through a post-transcriptional mechanism. Similarly, glucocorticoids down-regulated STC mRNA levels in the human fibrosarcoma cell line, HT1080. The specificity of the glucocorticoid-mediated decrease in STC mRNA abundance was shown using the glucocorticoid receptor antagonist, RU-486. Activation of the cAMP-signaling pathway in glucocorticoid-cultured AtT-20 cells transiently restored STC gene expression. Treatment of AtT-20 cells with the transcriptional inhibitor, actinomycin D, rescued steady-state STC mRNA levels from Dex-induced repression, indicating that the Dex-mediated decrease in STC gene expression requires current gene transcription. Taken together, these results describe a unique model system in which cAMP-stimulated events can reverse post-transcriptional repression of gene expression by glucocorticoids.

Evaluation of portable air samplers for monitoring airborne culturable bacteria.

Airborne culturable bacteria were monitored at five locations (three in an office/laboratory building and two in a private residence) in a series of experiments designed to compare the efficiency of four air samplers: the Andersen two-stage, Burkard portable, RCS Plus, and SAS Super 90 samplers. A total of 280 samples was collected. The four samplers were operated simultaneously, each sampling 100 L of air with collection on trypticase soy agar. The data were corrected by applying positive hole conversion factors for the Burkard portable, Andersen two-stage, and SAS Super 90 air samplers, and were expressed as log10 values prior to statistical analysis by analysis of variance. The Burkard portable air sampler retrieved the highest number of airborne culturable bacteria at four of the five sampling sites, followed by the SAS Super 90 and the Andersen two-stage impactor. The number of bacteria retrieved by the RCS Plus was significantly less than those retrieved by the other samplers. Among the predominant bacterial genera retrieved by all samplers were Staphylococcus, Bacillus, Corynebacterium, Micrococcus, and Streptococcus.

Dynamics of airborne fungal populations in a large office building.

The increasing concern with bioaerosols in large office buildings prompted this prospective study of airborne fungal concentrations in a newly constructed building on the Gulf coast. We collected volumetric culture plate air samples on 14 occasions over the 18-month period immediately following building occupancy. On each sampling occasion, we collected duplicate samples from three sites on three floors of this six-story building, and an outdoor sample. Fungal concentrations indoors were consistently below those outdoors, and no sample clearly indicated fungal contamination in the building, although visible growth appeared in the ventilation system during the course of the study. We conclude that modern mechanically ventilated buildings prevent the intrusion of most of the outdoor fungal aerosol, and that even relatively extensive air sampling protocols may not sufficiently document the microbial status of buildings.

TCR engagement of CD4+CD8+ thymocytes in vitro induces early aspects of positive selection, but not apoptosis.

Immature CD4/CD8 double-positive (DP) thymocytes expressing self MHC-restricted TCR are positively selected in response to TCR signals to survive and differentiate into functionally competent CD4 or CD8 single positive (SP) T cells. In contrast, DP precursors expressing autoreactive TCR are clonally deleted in response to TCR signals. We show here that in vitro TCR engagement of TCR(low) DP thymocytes rapidly triggers a variety of events considered to be hallmarks of positive selection in vivo. These include increased expression of CD5 and Bcl-2, termination of RAG-1 and pre-T(alpha) gene expression, and a switch in lck promoter usage. We also demonstrate that CD4- or CD28-mediated signals synergize with TCR signals to induce these outcomes. Finally, we show that the response of DP thymocytes to TCR engagement is selective in that clonal deletion, CD4/CD8 lineage commitment, and other events associated with maturation, such as changes in expression of Thy-1, HSA, MHC class I, and CD45-RB, were not induced. Thus, only subsets of maturational processes associated with positive selection in vivo were shown to be directly coupled to TCR signaling pathways at the DP stage. These observations support conclusions from in vivo systems suggesting that multiple, temporally separated TCR engagements are required to effect the entire spectrum of developmental changes associated with positive selection, and provide a conceptual and experimental framework for unraveling the complexity of positive selection.

Fyn can partially substitute for Lck in T lymphocyte development.

Lck, a Src family tyrosine kinase, transduces signals important for the development of alphabeta and gammadelta T cells. However, T cell development is only partially compromised in Lck-deficient mice, suggesting that other kinases may also transduce pre-TCR or TCR signals. One candidate is Fyn, a Src kinase coexpressed with Lck in immature and mature T cells. Here we show that T cell development is completely compromised in lck(-/-)fyn(-/-) mice. In addition, we demonstrate that expression of a gain-of-function mutant fyn(T) transgene completely restores production of immature CD4/CD8 double positive thymocytes and gammadelta T cells and improves the representation of CD4 or CD8 single positive thymocytes. These observations reveal that Fyn can subserve some Lck-like functions in T cell development.

Inactivation of Fac in mice produces inducible chromosomal instability and reduced fertility reminiscent of Fanconi anaemia.

Fanconi anaemia (FA) is an autosomal recessive disease characterized by bone marrow failure, variable congenital malformations and predisposition to malignancies. Cells derived from FA patients show elevated levels of chromosomal breakage and an increased sensitivity to bifunctional alkylating agents such as mitomycin C (MMC) and diepoxybutane (DEB). Five complementation groups have been identified by somatic cell methods, and we have cloned the gene defective in group C (FAC)(7). To understand the in vivo role of this gene, we have disrupted murine Fac and generated mice homozygous for the targeted allele. The -/- mice did not exhibit developmental abnormalities nor haematologic defects up to 9 months of age. However, their spleen cells had dramatically increased numbers of chromosomal aberrations in response to MMC and DEB. Homozygous male and female mice also had compromised gametogenesis, leading to markedly impaired fertility, a characteristic of FA patients. Thus, inactivation of Fac replicates some of the features of the human disease.

In vitro maturation of clonal CD4+CD8+ cell lines in response to TCR engagement.

Engagement of the TCR on immature CD4+CD8+ (DP) thymocytes by an appropriate peptide/MHC ligand evokes a complex program of maturation known as positive selection. As a result, DP thymocytes are rescued from programmed cell death, become committed to the CD4 or CD8 lineage, extinguish expression of V(D)J recombinase activity, and undergo further maturation. We describe here a panel of DP thymic lymphoma cell lines that, in response to in vitro TCR engagement, undergo many of the TCR-beta-induced maturation events that have been reported to accompany positive selection of DP thymocytes in vivo. These events include increased expression of CD5, CD69, CD45, TCR-alpha, and MHC class I, and decreased expression of Thy-1 and heat-stable Ag. In addition, we observed TCR-induced expression of the bcl-2 gene, a well described inhibitor of programmed cell death. Finally, TCR engagement decreased expression of recombinase-activating genes and terminal deoxynucleotidal transferase genes, as well as V(D)J recombinase activity. However, TCR engagement did not elicit demonstrable CD4/CD8 lineage commitment. These observations suggest that engagement of the TCR on these DP cell lines elicits multiple maturation events that are part of the positive selection developmental program, but not CD4/CD8 lineage commitment. Thus, these DP cell lines provide the opportunity to elucidate molecular mechanisms of maturation and CD4/CD8 lineage commitment in vitro.