Hydration status affects urea transport across rat urothelia

Although mammalian urinary tract epithelium (urothelium) is generally considered impermeable to water and solutes, recent data suggest that urine constituents may be reabsorbed during urinary tract transit and storage. To study water and solute transport across the urothelium in an in vivo rat model, we instilled urine (obtained during various rat hydration conditions) into isolated in situ rat bladders and, after a 1-h dwell, retrieved the urine and measured the differences in urine volume and concentration and total quantity of urine urea nitrogen and creatinine between instilled and retrieved urine in rat groups differing by hydration status. Although urine volume did not change >1.9% in any group, concentration (and quantity) of urine urea nitrogen in retrieved urine fell significantly (indicating reabsorption of urea across bladder urothelia), by a mean of 18% (489 mg/dl, from an instilled 2,658 mg/dl) in rats receiving ad libitum water and by a mean of 39% (2,544 mg/dl, from an instilled 6,204 mg/dl) in water-deprived rats, but did not change (an increase of 15 mg/dl, P = not significant, from an instilled 300 mg/dl) in a water-loaded rat group. Two separate factors affected urea nitrogen reabsorption rates, a urinary factor related to hydration status, likely the concentration of urea nitrogen in the instilled urine, and a bladder factor(s), also dependent on the animal's state of hydration. Urine creatinine was also absorbed during the bladder dwell, and hydration group effects on the concentration and quantity of creatinine reabsorbed were qualitatively similar to the hydration group effect on urea transport. These findings support the notion(s) that urinary constituents may undergo transport across urinary tract epithelia, that such transport may be physiologically regulated, and that urine is modified during transit and storage through the urinary tract.

The association of arterial shear and flow-mediated dilation in diabetes

While adjusting flow-mediated dilation (FMD), a measure of vascular function, for shear rate may be important when evaluating endothelial-dependent vasodilation, the relationship of FMD with shear rate in study populations with cardiovascular risk factors is unclear. We aimed to investigate the association of four measures of shear rate (peak shear rate (SR(peak)) and shear rate area under the curve through 30 seconds (SR(AUC 0-30)), 60 seconds (SR(AUC 0-60)), and time to peak dilation (SR(AUC 0-ttp))) with FMD in 50 study subjects with type 2 diabetes and mild hypertension undergoing baseline FMD testing for an exercise intervention trial. Associations among measures of shear rate and FMD were evaluated using Pearson's correlations and R(2). The four measures of shear rate were highly correlated within subjects, with Pearson's correlations ranging from 0.783 (p < 0.001) to 0.972 (p < 0.001). FMD was associated with each measure of shear rate, having a correlation of 0.576 (p < 0.001) with SR(AUC 0-30), 0.529 (p < 0.001) with SR(AUC 0-60), and 0.512 (p < 0.001) with SR(peak). Nine of 50 subjects (18%) did not dilate following the shear stimulus. Among the 41 responders, FMD had a correlation of 0.517 (p < 0.001) with SR(AUC 0-ttp) and similar correlations to those found in the full sample for SR(AUC 0-30), SR(AUC 0-60), and SR(peak). In conclusion, shear rate appears to explain up to a third of between-person variability in FMD response and our results support the reporting of shear rate and FMD with and without adjustment for shear rate in similar clinical populations with CVD risk factors.

Lean mass predicts hip geometry in men and women with non-insulin-requiring type 2 diabetes mellitus

Persons with type 2 diabetes mellitus (T2DM) are at increased risk for hip fracture despite normal bone mineral density (BMD). The contribution of body composition to hip geometry, a measure of hip strength, has not been studied in T2DM. We hypothesized that lean mass would predict hip geometry. Subjects (n=134) for this cross-sectional analysis were men and women aged 56 ± 6yr with non-insulin-requiring T2DM. Fat and lean mass were measured with dual-energy X-ray absorptiometry (DXA). Abdominal fat was measured with magnetic resonance imaging. Hip geometry parameters including section modulus, cross-sectional area, and buckling ratio were estimated from DXA using validated formulae. Subjects had normal BMD, elevated body mass indices (29-41 kg/m(2)), and controlled T2DM (hemoglobin A1c: 5.1-8.3%). In bivariate analysis, lean mass was positively associated with section modulus and cross-sectional area in both sexes (r=0.36-0.55, p<0.05). In multivariate analyses, lean mass remained a significant predictor of all hip strength estimates in both sexes. In women alone, fat mass predicted parameters of hip strength. These data demonstrate that lean mass is significantly associated with hip strength in subjects with non-insulin-requiring T2DM. Resistance exercises that build lean mass may be an intervention for hip fracture prevention in T2DM, although additional research is needed.

Lean mass and fat mass predict bone mineral density in middle-aged individuals with noninsulin-requiring type 2 diabetes mellitus

OBJECTIVE

Despite high bone mineral density (BMD), persons with type 2 diabetes are at greater risk of fracture. The relationship between body composition and BMD in noninsulin-requiring diabetes is unclear. The aim was to examine how fat and lean mass independently affect the skeleton in this population.

RESEARCH DESIGN AND METHODS

Subjects for this cross-sectional analysis were men (n = 78) and women (n = 56) aged 40-65 years (56 ± 6 years) with uncomplicated, noninsulin-requiring type 2 diabetes. Total body fat and lean mass, total body, hip and lumbar spine BMD were measured with dual energy X-ray absorptiometry. Magnetic resonance imaging measured total abdominal, visceral and subcutaneous (SQ) fat.

RESULTS

Subjects had normal all-site BMD and were obese to overweight (body mass index 29-41 kg/m(2)) with controlled diabetes (HbA1c women 6·6 ± 1·2%, men 6·7 ± 1·6%). Lean mass was positively associated with total body, hip, femoral neck and hip BMD in both sexes. Fat mass, abdominal total and SQ fat were associated with total body and hip BMD in women. In multivariate analyses adjusted for sex, lean mass significantly predicted total, hip and femoral neck BMD in men and women. In unadjusted models, lean mass continued to predict BMD at these sites in men; fat mass also predicted total body, femoral and hip BMD in women.

CONCLUSIONS

In men and women with uncomplicated, noninsulin-requiring diabetes, lean mass significantly predicted BMD at the total body, hip and femoral neck. Further research is needed to determine whether acquisition or maintenance of lean mass in T2DM can prevent hip fracture in this at-risk population.

Soft tissue management of children's open tibial fractures--a review of seventy children over twenty years

INTRODUCTION

The management of open tibial fractures in children represents a unique reconstructive challenge. The aim of the study was to evaluate the management of paediatric open tibial fractures with particular regard to soft tissue management.

PATIENTS AND METHODS

A retrospective case-note analysis was performed for all children presenting with an open tibial fracture at a single institution over a 20-year period for 1985 to 2005.

RESULTS

Seventy children were reviewed of whom 41 were males and 29 females. Overall, 91% (n = 64) of children suffered their injury as a result of a vehicle-related injury. The severity of the fracture with respect to the Gustilo classification was: Grade I, 42% (n = 29); Grade II, 24% (n = 17); Grade III, 34% (n = 24; 7 Grade 3a, 16 Grade 3b, 1 Grade 3c). The majority of children were treated with external fixation and conservative measures, with a mean hospital in-patient stay of 13.3 days. Soft tissue cover was provided by plastic surgeons in 31% of all cases. Four cases of superficial wound infection occurred (6%), one case of osteomyelitis and one case of flap failure. The limb salvage was greater than 98%.

CONCLUSIONS

In this series, complications were associated with delayed involvement of plastic surgeons. Retrospective analysis has shown a decreased incidence of open tibial fractures which is reported in similar studies. Gustilo grade was found to correlate with length of hospital admission and plastic surgery intervention. We advocate, when feasible, the use of local fasciocutaneous flaps (such as distally based fasciocutaneous and adipofascial flaps), which showed a low complication rate in children.

Bone mineral density after bone marrow transplantation in childhood: measurement and associations

This study examined the bone mineral density (BMD) of 46 (median age 16.3, 8-29) survivors of autologous and allogeneic bone marrow transplantation (BMT). Areal (g/m2) BMD was acquired with dual energy x-ray absorptiometry and volumetric (g/cm3) BMD values were calculated. Abnormal BMD was identified in 24% (11/46) of survivors with areal measures and 22% (10/46) with volumetric measures. Comparison of areal and volumetric BMD revealed the measures were highly correlated (r = 0.73, p<0.001) but clinical diagnosis of osteopenia/osteoporosis were not consistent. Volumetric z-scores were higher for 7/8 of the survivors who were < 3rd percentile for height. Associations of BMD and body composition and disease and treatment factors were assessed with multiple linear regression. When controlling for other significant associations and cumulative steroid dose, the body composition measure of fat mass index (FMI) was associated with higher volumetric BMD z-scores (CI: 0.006, 0.193; p = 0.037). CNS irradiation (CI: -1.710,-0.200; p = 0.015), age at time of testing (CI: -0.116, -0.024; p = 0.004) and female sex (CI: -1.375, -0.155; p = 0.015) were associated with lower volumetric BMD z-scores.

CONCLUSIONS

Childhood BMT survivors are at risk for diminished BMD. Areal and volumetric DEXA derived measures of BMD are highly correlated and volumetric measures may correct for underestimation of BMD in BMT survivors who are small for age. Survivors who received CNS irradiation, are older and female may be at greater risk for diminished BMD while fat mass is associated with higher BMD in childhood BMT survivors.

Prevalence and predictors of abnormal cardiovascular responses to exercise testing among individuals with type 2 diabetes: the Look AHEAD (Action for Health in Diabetes) study

OBJECTIVE

We examined maximal graded exercise test (GXT) results in 5,783 overweight/obese men and women, aged 45-76 years, with type 2 diabetes, who were entering the Look AHEAD (Action for Health in Diabetes) study, to determine the prevalence and correlates of exercise-induced cardiac abnormalities.

RESEARCH DESIGN AND METHODS

Participants underwent symptom-limited maximal GXTs. Questionnaires and physical examinations were used to determine demographic, anthropometric, metabolic, and health status predictors of abnormal GXT results, which were defined as an ST segment depression > or =1.0 mm, ventricular arrhythmia, angina pectoris, poor postexercise heart rate recovery (<22 bpm reduction 2 min after exercise), or maximal exercise capacity less than 5.0 METs. Systolic blood pressure response to exercise was examined as a continuous variable, without a threshold to define abnormality.

RESULTS

Exercise-induced abnormalities were present in 1,303 (22.5%) participants, of which 693 (12.0%) consisted of impaired exercise capacity. ST segment depression occurred in 440 (7.6%), abnormal heart rate recovery in 206 (5.0%), angina in 63 (1.1%), and arrhythmia in 41 (0.7%). Of potential predictors, only greater age was associated with increased prevalence of all abnormalities. Other predictors were associated with some, but not all, abnormalities. Systolic blood pressure response decreased with greater age, duration of diabetes, and history of cardiovascular disease.

CONCLUSIONS

We found a high rate of abnormal GXT results despite careful screening for cardiovascular disease symptoms. In this cohort of overweight and obese individuals with type 2 diabetes, greater age most consistently predicted abnormal GXT. Long-term follow-up of these participants will show whether these abnormalities are clinically significant.

The osmotic tissue expander: a 5-year experience

Tissue expansion is a valuable technique in soft tissue reconstruction. Osmotic expanders are self-inflating and obviate the need for repeated injections. In doing so, they eliminate port site problems and may reduce the potential to introduce infection. The use of such expanders has become more common in recent years. We report on our experience with the Osmed™ osmotic expanders over the last 5-years.

Remodelling of the pinna in myxoid degeneration of the ear

Idiopathic deformation of the pinna is not widely reported in the current literature. We present a series of cases in which patients have required surgery for spontaneous thickening and deformation of the auricular cartilage, and a description of a technique for surgical correction. Four cases of idiopathic deformation of the pinna are reported. Our preferred technique of scaphoid rim incision and anterior carving of the cartilage is described, with intra-operative photographs. Each patient reported spontaneous swelling of the upper poles of the ears beginning in the second or third decade of life. In 3 cases the deformity was bilateral, although in each of these cases one side was more severely affected than the other. Histology for these cases was reported as myxoid degeneration of the ear. All of the reported patients were pleased with the aesthetic outcome of their auricular remodelling. Currently, there are no typical patient demographics for idiopathic myxoid degeneration of the ear. We have achieved good aesthetic results by hand carving the anterior aspect of the deformed cartilage via scaphoid rim incisions.