Iron supplementation improves progressive fatigue resistance during dynamic knee extensor exercise in iron-depleted,nonanemic women

BACKGROUND: Tissue iron depletion may negatively affect endurance performance and muscle fatigability. OBJECTIVE: We investigated tissue-level iron depletion and progressive fatigue of the quadriceps during dynamic knee-extension exercise in young women. DESIGN: Twenty iron-depleted (serum ferritin < 20 micro g/L), nonanemic (hemoglobin > 110 g/L) women (macro x +/- SEM age: 29.1 +/- 1.2 y) received iron (iron group) or placebo (placebo group) for 6 wk in a randomized, double-blind trial (n = 10 per group). A protocol integrating 2-3-s maximal voluntary static contractions (MVCs) with dynamic knee extensions was used to assess fatigue. RESULTS: No significant differences between the groups in baseline iron status, MVC at rest, or MVC at the end of the protocol were observed. After treatment, serum iron and transferrin saturation increased significantly in the iron group (P = 0.02 and P = 0.03, respectively). Serum transferrin receptor concentrations increased significantly in the placebo group (P < 0.01) but not in the iron group. After treatment, the rate of decrease in MVC was attenuated in the iron group but not in the placebo group (P = 0.01). In the iron group, MVC at the sixth minute of the fatigue protocol and MVC at the end of the protocol were approximately 15% (P = 0.04) and approximately 27% higher (P < 0.01), respectively, after treatment. These improvements were not related to changes in iron-status indexes or tissue iron stores, although power was low (< 0.50) to detect these relations. CONCLUSIONS: Iron supplementation was associated with a significant improvement in muscle fatigability. Interpretation regarding the direct role of tissue iron status is limited by the study's low power to detect relations between tissue iron improvement and decreased muscle fatigue.     

How useful is docusate in patients at risk for constipation? A systematic review of the evidence in the chronically ill

The effectiveness of docusate for constipation has not been studied in the terminally ill. Controversy also exists concerning its effectiveness in the chronically ill. Because chronically ill patients and terminally ill patients have several risk factors for constipation in common, we undertook a systematic review of prospective controlled trials of oral docusate in the chronically ill to clarify the utility of this drug in populations with advanced disease. The data sources were Medline 1966-April 1997, CINAHL 1982-April 1997, Current Contents August 1996-April 1997, Cochrane Library, a hand search of Index Medicus 1940-1966, three palliative care journals, references in relevant articles and texts, and direct contact with experts. Prospective controlled trials evaluating oral docusate in humans with chronic illness and identifiable risk factors for, or preexisting, constipation were selected. Only materials abstracted in English or French were considered. Information was collected by two independent reviewers and included patient demographic data, study design, dose of docusate, outcomes of stool consistency, stool frequency, need for other laxatives, and assessment of methodologic and reporting quality. Of nine identified studies, four were eligible. These incorporated three different designs and sample sizes that ranged from 15 to 74. Quality assessment scores were low (range 0.46-0.52 with a perfect score being 1.0). Three studies were flawed in blinding of treatment allocation and the use of co-interventions. All studies showed a small trend toward increased stool frequency on docusate. Because of significant clinical heterogeneity in the identified studies, pooled data analysis was not feasible. At present, the use of docusate for constipation in palliative care is based on inadequate experimental evidence. Randomized controlled trials with chronically ill patients and patients with advanced disease are needed to determine its role in prevention and treatment of constipation.     

Postoperative infections following total knee replacement: an epidemiological study

From January 1991 to June 1997 217 patients undergoing monolateral or bilateral total knee replacement (TKR) were consecutively enrolled in a prospective study on the incidence of postoperative infections and related risk factors. Regional antimicrobial prophylaxis (teicoplanin 400 mg) was used in 263 (95%) prostheses implanted; in the remaining 14 implants (5%) perioperative antibiotic prophylaxis (teicoplanin 800 mg) was administered as usual by systemic route. None of the patients experienced local or systemic adverse effects. Over the 2-year follow-up period, 8 (2.9%) primary site infectious complications were recorded, i.e. 4 superficial infections, which were cured without involvement of the prostheses, and 4 deep infections, which required prosthesis removal. Six infections occurred in patients who had undergone previous surgery of the same knee joint, and 2 in patients undergoing primary TKR (p= 0.0005); diabetic patients had infections (13%) more frequently than non-diabetic patients (1.9%, p=0.01). Staphylococci were the leading organisms isolated from infections; however 3 strains of Escherichia coli were isolated from patients who had undergone a previous prosthesis implantation at the same knee joint. Regional administration of teicoplanin appears to be a safe and valuable prophylactic technique; however, in patients at risk of infection a prophylactic regimen which is also active against gram-negative bacteria should probably be considered.     

Agreement between physicians and parents in rating functional ability of children with juvenile idiopathic arthritis

Objective  

To investigate concordance between physicians and parents in rating the degree of functional ability of children with juvenile idiopathic arthritis (JIA).     

Competition–defense tradeoffs and the maintenance of plant diversity

Ecologists have long observed that consumers can maintain species diversity in communities of their prey. Many theories of how consumers mediate diversity invoke a tradeoff between species’ competitive ability and their ability to withstand predation. Under this constraint, the best competitors are also most susceptible to consumers, preventing them from excluding other species. However, empirical evidence for competition–defense tradeoffs is limited and, as such, the mechanisms by which consumers regulate diversity remain uncertain. We performed a meta-analysis of 36 studies to evaluate the prevalence of the competition–defense tradeoff and its role in maintaining diversity in plant communities. We quantified species’ responses to experimental resource addition and consumer removal as estimates of competitive ability and resistance to consumers, respectively. With this analysis, we found mixed empirical evidence for a competition–defense tradeoff; in fact, competitive ability tended to be weakly positively correlated with defense overall. However, when present, negative relationships between competitive ability and defense influenced species diversity in the manner predicted by theory. In the minority of communities for which a tradeoff was detected, species evenness was higher, and resource addition and consumer removal reduced diversity. Our analysis reframes the commonly held notion that consumers structure plant communities through a competition–defense tradeoff. Such a tradeoff can maintain diversity when present, but negative correlations between competitive ability and defense were less common than is often assumed. In this respect, this study supports an emerging theoretical paradigm in which predation interacts with competition to both enhance and reduce species diversity.     

The health of widows in the year following bereavement

has been written during the past decade about the mortality and morbidity which may follow conjugal bereavement [1–4]. Existing studies of morbidity do not however enable us to draw any substantial conclusions about the prevalence of such consequences in widows and widowers. Either the population of bereaved persons has been a highly selected one, commonly available for study because they have been referred for psychiatric treatment, or there has been no utilization of a non-bereaved control group, the desirability of which is heightened by the tendency towards some deterioration in physical and mental health in middle age [5].

This present study developed as one segment of a major research endeavour, aimed ultimately at the identification in advance of those widows most likely to suffer untoward physical and/or psychological consequences following conjugal bereavement [6]. Our major focus has been on the subject's interaction with her social network during the three months immediately following the bereavement [7], the whole study being conceptualized within the framework of crisis theory [8]. Our findings on the health of widows, however, were of such interest that it seemed worthwhile to examine suitably matched control groups in order to determine more truly the prevalence of health deterioration following bereavement. As well as information about the overall prevalence of health deterioration in two samples of widows, one in Boston, Massachusetts and the other in Sydney, Australia, our techniques also enabled us to gather information about the specific symptoms and syndromes manifested by the subjects and the matched controls.     

Autoantibodies in juvenile dermatomyositis

Fourteen patients with juvenile dermatomyositis (JDM) have been investigated for the presence of several serum autoantibodies: antinuclear (ANA), anti-single-stranded and double-stranded DNA, anti-histones, anti-Sm, anti-ribonucleoprotein, anti-SSA/SSB, anti-PM-1, anti-Jo-1, anti-mitochondrial, anti-smooth muscle, anti-gastric parietal cells, anti-cardiolipin (ACA) antibodies and rheumatoid factor. Patients were negative for all autoantibodies except for ANA and ACA. ANA were detected in 50% of the patients when tested on rat liver, but the percentage of positivity rose to 86% when HEp-2 cells were used as substrate. This finding suggests that HEp-2 cells represent a more sensitive substrate than rat liver for the detection of ANA in JDM. Three patients were positive for ACA; two of these presented vascular complications, thus suggesting a possible relationship between ACA and vascular involvement in JDM.