Correlates of Physical Functioning and Performance Across the Spectrum of Kidney Function.

The aim of this study was to determine the extent to which poor physical functioning, low participation in physical activity, and muscle atrophy observed among patients on hemodialysis are evident in the earlier stages of chronic kidney disease (CKD). We enrolled adults in three groups: no CKD, Stages 3 to 4 CKD, and hemodialysis. Outcomes measured were physical activity, muscle size, thigh muscle strength, physical performance, and self-reported physical function. Patients with CKD had muscle area intermediate between the no CKD and hemodialysis groups, but they had low levels of physical activity that were similar to the hemodialysis group. Physical activity and muscle size were significantly associated with all outcomes. Kidney function was not significantly associated with muscle strength or physical performance after adjustment for physical activity and muscle size. In conclusion, interventions aimed to increase muscle mass and energy expenditure might have an impact on improving physical function of CKD patients.

Postdialysis fatigue is associated with sedentary behavior.

Postdialysis fatigue (PDF) is a common and debilitating phenomenon that adversely affects the quality of life of hemodialysis patients. Excessive ultrafiltration and rapid osmolar flux are implicated in the pathogenesis of PDF, but simple adjustments do not always ameliorate this symptom. Increased physical activity has long been associated with reduced fatigue in sedentary fatigued patients. The aim of the study was to examine the extent to which physical activity is associated with PDF. This was a retrospective cross-sectional study of hemodialysis patients (n = 58, age 55 ± 13 years, 38 M, 20 F). Physical activity was measured by self-report using the Human Activity Profile (HAP) (n = 58) and accelerometry (n = 26). Postdialysis fatigue was assessed by a questionnaire rating frequency, severity, and duration of symptoms. 86% (50/58) of patients reported PDF ranging from mild to severe. The PDF index was inversely correlated with the adjusted score of the HAP (p < 0.05). Least squares linear regression was used to assess the association of physical activity with PDF, controlling for Kt/V and dialysis vintage. In the adjusted model (R2 = 0.40), physical activity remained the most significant predictor (p < 0.01) of PDF after adjusting for Kt/V and/or vintage. Further studies are needed to evaluate whether increasing habitual physical activity can mitigate PDF symptoms.

Resistance training alters cytokine gene expression in skeletal muscle of adults with type 2 diabetes.

Resistance training results in muscle hypertrophy and improves glycemic control in patients with type 2 diabetes. Whether resistance training modulates inflammation in muscles of diabetic patients remains unknown. We examined the expression of genes encoding the cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and transforming growth factor-beta1 (TGF-beta1) as well as the pan-leukocyte marker CD18. Thirty men and women (67+/-7 years) were randomized to either 16 weeks of resistance training and usual diabetes care (EX) or to usual diabetes care only (CON). Muscle biopsies were obtained from the vastus lateralis muscle prior to the 16-week intervention, and 72 h following the maximal strength test post-intervention. Fiber cross-sectional area (CSA) was determined following ATPase staining. Cytokine and CD18 transcript levels were assessed by real-time PCR. Resistance training increased CSA of type I and II fibers (both P <0.05) and IL-1beta transcript levels (P = 0.05). TNF-alpha (P<0.05) and TGF-beta1 transcripts (P<0.05) increased over time in the EX group, but these increases did not differ from those in the CON group. In both groups, the increase in CD18 transcripts remained minimal. The two groups differ by the relationship between changes in CD18 and changes in cytokine transcripts, suggesting that resistance training affects the source of cytokines in muscle. Our studies establish that resistance training in older adults with type 2 diabetes results in muscle fiber hypertrophy, despite a greater accumulation of inflammatory cytokine transcripts in muscle.

Markedly elevated serum biotinidase activity may indicate glycogen storage disease type Ia.

We report two children who presented with symptoms suggestive of biotinidase deficiency. Rather than deficiency, markedly elevated serum biotinidase activities were found. Based upon literature reports of elevated biotinidase activities in children with glycogen storage disease (GSD) type Ia, we considered the latter in our differential diagnosis and subsequently confirmed GSD type Ia in both patients by enzymatic testing. GSD type Ia should be considered in children with markedly elevated serum biotinidase activity.

Resistance training to counteract the catabolism of a low-protein diet in patients with chronic renal insufficiency. A randomized, controlled trial.

BACKGROUND: Chronic renal insufficiency leads to muscle wasting, which may be exacerbated by low-protein diets prescribed to delay disease progression. Resistance training increases protein utilization and muscle mass. OBJECTIVE: To determine the efficacy of resistance training in improving protein utilization and muscle mass in patients with chronic renal insufficiency treated with a low-protein diet. DESIGN: Randomized, controlled trial. SETTING: Tufts University, Boston, Massachusetts. PATIENTS: 26 older patients with moderate renal insufficiency (17 men, 9 women) who had achieved stabilization on a low-protein diet. INTERVENTION: During a run-in period of 2 to 8 weeks, patients were instructed and their adherence to the low-protein diet (0.6 g/kg of body weight per day) was evaluated. They were randomly assigned to a low-protein diet plus resistance training (n = 14) or a low-protein diet alone (n = 12) for 12 weeks. MEASUREMENTS: Total body potassium, mid-thigh muscle area, type I and II muscle-fiber cross-sectional area, and protein turnover. RESULTS: Mean protein intake was 0.64 +/- 0.07 g/kg per day after stabilization. Total body potassium and type I and II muscle-fiber cross-sectional areas increased in patients who performed resistance training by a mean (+/-SD) of 4% +/- 8%, 24% +/- 31%, and 22% +/- 29%, respectively, compared with those who did not. Leucine oxidation and serum prealbumin levels also improved significantly. Patients assigned to resistance training maintained body weight compared with those who were not. Improvement in muscle strength was significantly greater with resistance training (32% +/- 14%) than without (-13% +/- 20%) (P < 0.001). CONCLUSION: By improving muscle mass, nutritional status, and function, resistance training seems to be effective against the catabolism of a low-protein diet and uremia in patients with renal failure.

Clinical responses to bone marrow transplantation in children with severe osteogenesis imperfecta.

Preclinical models have shown that transplantation of marrow mesenchymal cells has the potential to correct inherited disorders of bone, cartilage, and muscle. The report describes clinical responses of the first children to undergo allogeneic bone marrow transplantation (BMT) for severe osteogenesis imperfecta (OI), a genetic disorder characterized by defective type I collagen, osteopenia, bone fragility, severe bony deformities, and growth retardation. Five children with severe OI were enrolled in a study of BMT from human leukocyte antigen (HLA)-compatible sibling donors. Linear growth, bone mineralization, and fracture rate were taken as measures of treatment response. The 3 children with documented donor osteoblast engraftment had a median 7.5-cm increase in body length (range, 6.5-8.0 cm) 6 months after transplantation compared with 1.25 cm (range, 1.0-1.5 cm) for age-matched control patients. These patients gained 21.0 to 65.3 g total body bone mineral content by 3 months after treatment or 45% to 77% of their baseline values. With extended follow-up, the patients' growth rates either slowed or reached a plateau phase. Bone mineral content continued to increase at a rate similar to that for weight-matched healthy children, even as growth rates declined. These results suggest that BMT from HLA-compatible donors may benefit children with severe OI. Further studies are needed to determine the full potential of this strategy.

Marginal protein intake results in reduced plasma IGF-I levels and skeletal muscle fiber atrophy in elderly women.

We investigated the effects of dietary protein on plasma IGF-I levels and muscle fiber cross-sectional area (CSA). Twelve healthy elderly women were randomly assigned to a weight-maintaining diet containing either 1.47 (marginal) or 2.94 (adequate) g protein/kg body cell mass (BCM)/d, (0.45 and 0.92 g/kg body weight/d, respectively) for 10wks. Plasma IGF-I levels and muscle fiber areas and distributions were evaluated at baseline and 10wks. After 10wks, both IGF-I and type I fiber CSA had declined significantly in subjects fed the marginal diet (30.1+/-2.1% and 32.7+/-7.9%, respectively) while they increased in those fed the adequate diet (19.5+/-7.0% and 22.3+/-7.5%, for IGF-I and type I CSA, respectively). The change in IGF-I was the only significantly associated with the change in type I fiber CSA (r2=0.70; p<0.03). These findings show that marginal dietary protein intakes will result in losses of muscle mass in the elderly and suggest a role for plasma IGF-I as a biochemical marker for the histological changes in skeletal muscle.

Transplantability and therapeutic effects of bone marrow-derived mesenchymal cells in children with osteogenesis imperfecta.

In principle, transplantation of mesenchymal progenitor cells would attenuate or possibly correct genetic disorders of bone, cartilage and muscle, but clinical support for this concept is lacking. Here we describe the initial results of allogeneic bone marrow transplantation in three children with osteogenesis imperfecta, a genetic disorder in which osteoblasts produce defective type I collagen, leading to osteopenia, multiple fractures, severe bony deformities and considerably shortened stature. Three months after osteoblast engraftment (1.5-2.0% donor cells), representative specimens of trabecular bone showed histologic changes indicative of new dense bone formation. All patients had increases in total body bone mineral content ranging from 21 to 29 grams (median, 28), compared with predicted values of 0 to 4 grams (median, 0) for healthy children with similar changes in weight. These improvements were associated with increases in growth velocity and reduced frequencies of bone fracture. Thus, allogeneic bone marrow transplantation can lead to engraftment of functional mesenchymal progenitor cells, indicating the feasibility of this strategy in the treatment of osteogenesis imperfecta and perhaps other mesenchymal stem cell disorders as well.

Strength gains without muscle injury after strength training in patients with postpolio muscular atrophy.

We evaluated changes in the dynamic and isometric strength in the newly weakened quadriceps muscles and asymptomatic triceps muscles of 6 patients with postpolio muscular atrophy (PPMA) after 10 weeks of progressive resistance strength training. Alterations in muscle size were determined with magnetic resonance imaging. Serum creatine kinase levels were measured throughout training, and histological signs of muscle injury and changes in muscle fiber size and types were assessed with muscle biopsies before and after training. Exercise training led to an increase in dynamic strength of 41% and 61% for the two knee extensor tests, and 54% and 71% for the two elbow extensor tests. Up to 20% of the improvement was maintained 5 months after cessation of training. Isometric strength, whole muscle cross-sectional areas of quadriceps and triceps muscles, and serum muscle enzymes did not change. No destructive histopathological changes were noted in the repeat muscle biopsies, and no consistent changes in muscle fiber size or fiber type percentages were observed. These results demonstrate that a supervised resistance training program can lead to significant gains in dynamic strength of both symptomatic and asymptomatic muscles of PPMA patients without serological or histological evidence of muscular damage.

Characterization of an unbalanced de novo rearrangement by microsatellite polymorphism typing and by fluorescent in situ hybridization.

Unbalanced de novo rearrangements, difficult to characterize by conventional cytogenetic techniques, may be elucidated by molecular approaches. By dinucleotide repeat polymorphism typing and fluorescence in situ hybridization (FISH), we have defined the composition of an unbalanced de novo translocation (46,XX,15p+) in a child with multiple congenital anomalies. Use of a microsatellite repeat D5S208 (localized to 5p15) and polymerase chain reaction (PCR) analysis confirmed that the extra segment originated from the short arm of chromosome 5. Amplification of the patient's DNA with primers for dinucleotide repeats D5S350 and D5S118 showed that the entire 5p (from 5pter to 5q11) was present in 3 copies. FISH confirmed the trisomic status of 5p, and further revealed the presence of centromeres of both chromosomes 5 and 15 on the rearranged chromosome thus delineating its dicentric nature. This information allowed us to redefine the de novo rearrangement in this patient as 46,XX,dic der(15)t(5;15)(q11;p11).

Neoplasms in Proteus syndrome.

We report on 2 children with Proteus syndrome who developed neoplasms. Patient 1 had a probable mesothelioma, although papillary carcinoma of the thyroid could not be completely ruled out. Patient 2 had bilateral ovarian serous cystadenomas with nuclear atypia. Other unusual neoplasms in Proteus syndrome are discussed, together with their etiologic and pathogenetic possibilities.

Prenatal diagnosis of isolated bilateral microphthalmia with confirmation by evaluation of products of conception obtained by dilation and evacuation.

We describe the prenatal diagnosis of isolated bilateral fetal microphthalmia in a woman at increased risk of having a fetus with microphthalmia. Ultrasound examinations at 16.1 and 19.5 weeks' gestation demonstrated bilateral fetal microphthalmia with no other associated structural defects. The patient elected to terminate her pregnancy at 19.5 weeks. Pathological evaluation of the products of conception obtained by dilation and evacuation confirmed the prenatal diagnosis of isolated bilateral fetal microphthalmia.

Elucidation of the centromere involvement in an inversion (13) by fluorescent in situ hybridisation.

A newborn infant with phenotypic features of trisomy for distal 13q was found to have recombinant inversion duplication involving the (13)(q22-->qter) region. Parental karyotypes showed that the mother had a normal 46,XX complement and the father had an apparently balanced pericentric inversion of a chromosome 13. Because of the unusual nature of the inversion, the exact position of the centromere on the father's inverted chromosome 13 was difficult to assign by GTG banding, even on prometaphase chromosomes. CBG and NOR banding were not informative in determining the location of the centromere. Fluorescent in situ hybridisation with an alpha satellite DNA probe for D13Z1/D21Z1 helped in confirming the exact position of the centromere in the rearranged paternal chromosome. Thus, the origin of the proband's abnormal chromosome 13 was clarified.

Deletion of chromosome 15pter-->q11.2 due to t(Y;15) in a boy with Prader-Willi syndrome.

Chromosome analysis of lymphocytes from a patient with the clinical presentation of Prader-Willi syndrome showed the presence of 45 chromosomes, including a der(Y) resulting from an unbalanced t(Y;15)(q12;q11.2). In situ hybridization using DYZ3 and DYZ2 showed positive signals at the paracentromeric region on the short arm and at the heterochromatic region of the long arm of the Y chromosome, respectively. The Prader-Willi syndrome in this patient is caused by the deficiency of a very small region involving 15cen-->q11.2.

Design of an artificial skin. II. Control of chemical composition.

Detailed methodology is described for the reproducible preparation of collagen--glycosaminoglycan (GAG) membranes with known chemical composition. These membranes have been used to cover satisfactorily large experimental full-thickness skin wounds in guinea pigs over the past few years. Such membranes have effectively protected these wounds from infection and fluid loss for over 25 days without rejection and without requiring change or other invasive manipulation. When appropriately designed for the purpose, the membranes have also strongly retarded wound contraction and have become replaced by newly synthesized, stable connective tissue. In our work, purified, fully native collagen from two mammalian sources is precipitated from acid dispersion by addition of chondroitin 6-sulfate. The relative amount of GAG in the coprecipitate varies with the amount of GAG added and with the pH. Since coprecipitated GAG is generally eluted from collagen fibers by physiological fluids, control of the chemical composition of membranes is arrived at by crosslinking the collagen--GAG ionic complex with glutaraldehyde, or, alternately, by use of high-temperature vacuum dehydration. Appropriate use of the crosslinking treatment allows separate study of changes in membrane composition due to elution of GAG by extracellular fluid in animal studies from changes in composition due to enzymatic degradation of the grafted or implanted membrane in these studies. Exhaustive in vitro elution studies extending up to 20 days showed that these crosslinking treatments insolubilize in an apparently permanent manner a fraction of the ionically complexed GAG, although it could not be directly confirmed that glutaraldehyde treatment covalently crosslinks GAG to collagen. By contrast, the available evidence suggests strongly that high-temperature vacuum dehydration leads to formation of chemical bonds between collagen and GAG. Procedures are described for control of insolubilized and "free" GAG in these membranes as well as for control of the molecular weight between crosslinks (Mc). The insolubilized GAG can be controlled in the range 0.5--10 wt. % while "free" GAG can be independently controlled up to at least 25 wt. %; Mc can be controlled in the range 2500--40,000. Studies by infrared spectroscopy have shown that treatment of collagen--GAG membranes by glutaraldehyde or under high-temperature vacuum does not alter the configuration of the collagen triple helix in the membranes. Neither do these treatments modify the native banding pattern of collagen as viewed by electron microscopy. Collagen--GAG membranes appear to be useful as chemically well-characterized, solid macromolecular probes of biomaterial--tissue interactions.

Correlation of in vivo collagen degradation rate with in vitro measurements.

The rate of in vitro enzymatic degradation of various materials based on collagen has been determined by a novel mechanochemical method, and has been compared with the extent of degradation resulting from subcutaneous implantation in guinea pigs. In vitro data correlate well with in vivo data. It is suggested that the simple in vitro method described is an effective means of screening a large number of materials based on collagen for their ability to resist degradation during implantation in animals.