Scaling maximal oxygen uptake to predict cycling time-trial performance in the field: a non-linear approach

The purpose of the present article is to identify the most appropriate method of scaling for differences in body mass when assessing the energy cost of time-trial cycling. The data from three time-trial cycling studies were analysed (N=79) using a proportional power-function ANCOVA model. The maximum oxygen uptake-to-mass ratio found to predict cycling speed was precisely the same as that derived by Swain for sub-maximal cycling speeds (10, 15 and 20 mph). The analysis was also able to confirm a proportional curvilinear association between cycling speed and energy cost, given by The model predicts, for example, that for a male cyclist (72 kg) to increase his average speed from 30 km h^–1 to 35 km h^–1, he would require an increase in from 2.36 l min^–1 to 3.44 l min^–1, an increase of 1.08 l min^–1. In contrast, for the cyclist to increase his mean speed from 40 km h^–1 to 45 km h^–1, he would require a greater increase in from 4.77 l min^–1 to 6.36 l min^–1, i.e. an increase of 1.59 l min^–1. The model is also able to accommodate other determinants of time-trial cycling, e.g. the benefit of cycling with a side wind (5% faster) compared with facing a predominatly head/tail wind (P<0.05). Future research could explore whether the same scaling approach could be applied to, for example, alternative measures of recording power output to improve the prediction of time-trial cycling performance.     

An exploration into the role of depression and self-efficacy on township men who have sex with men's ability to engage in safer sexual practices

Men who have sex with men (MSM) in South Africa remain at particular risk of HIV infection. The Ukwazana baseline survey is the first to explore this risk in relation to psychological factors associated with unprotected anal intercourse (UAI). A cohort of 316 MSM from township peri-urban Cape Town took part in the survey. The survey found that 55.2% had engaged in UAI over the preceding 6 months. Depression was significantly associated with UAI. Respondents with self-efficacy scores less than two standard deviations above the mean were also more likely to have engaged in UAI. A Sobel test for mediation highlighted that the depression–UAI association was partially mediated by self-efficacy, indicating that most of the effect of depression on UAI was not covarying with self-efficacy. This study, therefore, highlights that both depression and self-efficacy should be considered factors to be addressed in HIV-prevention programmes aimed at peri-urban MSM.     

Antimicrobial resistance of uropathogens in women with acute uncomplicated cystitis from primary care settings

We assessed the antimicrobial resistance patterns of all urine samples submitted for culture from outpatient women aged ≥14 years with diagnosis of uncomplicated cystitis over a 24-month period (2007–2009) in the city of Fortaleza, Brazil. Only bacterial growth of a single uropathogen with ≥10⁵ CFU/mL was considered for analysis. The Pearson’s chi-square test was used for bivariate correlations. Escherichia coli presented the highest prevalence (64.7%). Coagulase-negative staphylococcus was more common in younger than in older women (P = 0.003). Gentamicin presented the lowest overall resistance pattern (3.5% resistant), followed by ceftriaxone (5%) and norfloxacin (7.5%). Ampicillin and trimethoprim-sulfamethoxazole were the least active agents with 63.7% and 39.8% of resistance, respectively. The resistant rate to trimethoprim-sulfamethoxazole was significantly higher among E. coli than non-E. coli isolated. Among ciprofloxacin-resistant E. coli strains, only 3.4% were resistant to nitrofurantoin. We conclude that trimethoprim-sulfamethoxazole follows a worldwide tendency of antimicrobial increasing resistance and it should be avoided as first-line empirical treatment for urinary tract infections.     

Tuberculosis-associated chronic kidney disease

Extrapulmonary tuberculosis (TB) account for approximately 15-20% of TB cases in immunocompetent patients. The genitourinary system is the third most commonly affected site. We report the case of a 20-year-old man admitted with fever, chills, dry cough, right flank pain, and oliguria who developed renal function loss. The pyelogram evidenced silence of the right kidney, and the abdominal and pelvic magnetic resonance showed significant dilation of the right pyelocaliceal system and proximal ureter. Biopsies of renal cortex and retroperitoneal lymph nodes showed caseous granuloma consistent with TB. Treatment was started with rifampicin, isoniazid, pyrazinamide, and ethambutol, and the patient presented a favorable outcome but with non-dialytic chronic kidney disease. This case illustrates a case of chronic kidney disease secondary to TB in a young, otherwise healthy man.