The effect of corrective surgery on energy expenditure during ambulation in children with cerebral palsy

Mechanical efficiency, heart rate, blood lactate, and some other variables were studied in six children with cerebral palsy who walked on a treadmill before and after corrective surgery. During each test, conducted at each child's naturally selected speed, two situations were studied: steady state level walking for 9 min, and then walking at an increasing inclination up to 20% for another 10 min. During the test the subjects were allowed to hold on to a handrail to eliminate the risk of falling off the treadmill. The corrective surgery resulted in a 5% reduction in oxygen consumption per kg body mass during level walking. The subjects' levels of physical fitness, as estimated from oxygen pulse, however, were unchanged. These results are indicative of a biomechanical improvement due to the corrective surgery. While walking at a 20% inclination the subjects off loaded themselves to different degrees on the handrail which influenced the results. Their feeling of exhaustion at this load was probably due to local factors, since heart rate was well below maximal values, and blood lactate, respiratory exchange ratio and ventilatory equivalent also indicated that they were below their anaerobic thresholds (50-60% of maximal oxygen uptake).     

Near Infrared Optical Projection Tomography for Assessments of β-cell Mass Distribution in Diabetes Research

By adapting OPT to include the capability of imaging in the near infrared (NIR) spectrum, we here illustrate the possibility to image larger bodies of pancreatic tissue, such as the rat pancreas, and to increase the number of channels (cell types) that may be studied in a single specimen. We further describe the implementation of a number of computational tools that provide: 1/ accurate positioning of a specimen''s (in our case the pancreas) centre of mass (COM) at the axis of rotation (AR)²; 2/ improved algorithms for post-alignment tuning which prevents geometric distortions during the tomographic reconstruction² and 3/ a protocol for intensity equalization to increase signal to noise ratios in OPT-based BCM determinations³. In addition, we describe a sample holder that minimizes the risk for unintentional movements of the specimen during image acquisition. Together, these protocols enable assessments of BCM distribution and other features, to be performed throughout the volume of intact pancreata or other organs (e.g. in studies of islet transplantation), with a resolution down to the level of individual islets of Langerhans.     

Abatacept Treatment Does Not Preserve Renal Function in the Streptozocin-Induced Model of Diabetic Nephropathy

Diabetic nephropathy (DN) is one of the most severe complications of diabetes and remains the largest cause of end-stage renal disease in the Western world. Treatment options are limited and novel therapies that effectively slow disease progression are warranted. Previous work suggested that treatment with CTLA4-Ig (abatacept), a molecule that binds and blocks B7-1 and is licensed for the treatment of rheumatoid arthritis, could ameliorate DN. This study was designed to assess whether B7-1 signalling constitutes a promising therapeutic pathway for DN. Mice injected with streptozotocin (STZ) were treated with abatacept and glycemia and renal function were assessed. No differences were found in diabetes progression, albumin excretion rates or albumin/creatine ratios, while mesangial expansion was unaltered at endpoint. Except for increased renal CCL5, treatment did not affect a panel of gene expression endpoints reflecting early fibrotic changes, inflammation and kidney injury. Finally, abatacept treatment effectively reduced the accumulation of activated CD4⁺ T cells in the kidney, suggesting that renal T cell inflammation is not a driving factor in the pathology of the STZ model. In conjunction with the recent data discounting the expression of B7-1 on podocytes, our present data do not support a role for abatacept in DN treatment.     

On the substrate specificity of human CYP27A1: implications for bile acid and cholestanol formation

The mitochondrial sterol 27-hydroxylase (CYP27A1) is required for degradation of the C27-sterol side chain in bile acid biosynthesis. CYP27A1 seems, however, to have roles beyond this, as illustrated by patients with a deficient sterol 27-hydroxylase due to mutations of the CYP27A1 gene [cerebrotendinous xanthomatosis (CTX)]. These subjects have symptoms ranging from accumulation of bile alcohols and cholestanol to accelerated atherosclerosis and progressive neurologic impairment. The present work describes a detailed investigation on the substrate specificity of recombinant human CYP27A1. In accordance with some previous work with rat liver mitochondria, the activity in general increased with the polarity of the substrate. An obvious example was the finding that cholesterol was 27-hydroxylated more efficiently than cholesterol oleate but less efficiently than cholesterol sulfate. The oxysterols 24S-hydroxycholesterol and 25-hydroxycholesterol were 27-hydroxylated less efficiently than cholesterol, possibly due to steric hindrance. Surprisingly, sterols with a 3-oxo-Delta4 structure were found to be hydroxylated at a much higher rate than the corresponding sterols with a 3beta-hydroxy-Delta5 structure. The rates of hydroxylation of the sterols were: 7alpha-hydroxy-4-cholesten-3-one>4-cholesten-3-one>7alpha-hydroxycholesterol>24-hydroxy-4-cholesten-3-one> cholesterol>25-hydroxy-4-cholesten-3-one>24-hydroxycholesterol>or=25-hydroxycholesterol. The possibility is discussed that the findings may have implications for oxysterol-mediated regulation of gene expression. The very high activity of CYP27A1 towards the cholestanol precursor 4-cholesten-3-one may be of importance in connection with the accumulation of cholestanol in patients with CTX.     

Alveolar fluid clearance in late-gestational guinea pigs after labor induction: mechanisms and regulation

We tested the hypothesis that labor-induced epinephrine release would stimulate alveolar fluid clearance in preterm fetuses. Preterm fetuses were obtained by cesarean section from timed-pregnant guinea pigs at 61-69 days postconception. Fetal guinea pigs were euthanized and placed on continuous positive airway pressure oxygenation, and an isosmolar 5% albumin solution was instilled. Alveolar fluid clearance was measured over 1 h. The fetal lung began to absorb fluid at 64-66 days postconception, and at birth, alveolar fluid clearance quadrupled. Baseline alveolar fluid clearance when present was sensitive to propranolol inhibition and depended on beta-adrenergic stimulation. Measurements of plasma epinephrine in fetal animals confirmed high epinephrine levels in 66- to 69-day postconception fetuses. Prenatal alveolar fluid clearance when present was highly amiloride sensitive, suggesting that amiloride-sensitive Na+ channels were critical. Oxytocin-induced labor initiated an amiloride- and propranolol-sensitive net alveolar fluid clearance in 61-day-gestation animals. Moreover, oxytocin induced significant epinephrine release in all fetuses. These results have clinical implications for infants delivered by cesarean section before the onset of labor. Use of pharmacological agents to induce labor may reduce the occurrence and severity of perinatal respiratory distress.     

Investigation of interfacial capacitance of Pt,Ti and TiN coated electrodes by electrochemical impedance spectroscopy

Electrochemical processes at the electrode-electrolyte (body fluid) interface are of ultimate importance for stimulating/sensing electrode function. A high electrode surface area is desirable for safe stimulation through double-layer charging and discharging. Pt and Pt-Ir alloys have been the most common electrode materials. The use of TiN coating as the surface layer on the electrode has found increasing interest because of its metal-like conductivity, excellent mechanical and chemical properties, and the fact that it can be deposited with a high surface area. In this work, electrochemical impedance spectroscopy (EIS), which is a sensitive and non-destructive technique and widely used for characterization of electrical properties of electrode-electrolyte interfaces, was applied to investigate pure Pt and Ti, and TiN coated electrodes exposed to a phosphate-buffered-saline (PBS) solution. Platinized Pt and Ti were also studied for comparison. The capacitance value of the electrodes in PBS was obtained through quantitative analysis of the EIS spectra. The results reveal that the capacitance of the TiN coated electrodes with a rough surface is several hundreds times higher than that of a smooth Pt surface. Platinization of Ti can also increase the capacitance to the same extent as platina. EIS has been shown to be a powerful technique for characterization of stimulating/sensing electrodes.     

Fibroblast growth factor signaling is required for the proliferation and patterning of progenitor cells in the developing anterior pituitary

The proliferation and patterning of progenitor cells in the anterior pituitary require signals derived from the neuroepithelium of the juxtaposed infundibulum. The infundibulum expresses Fibroblast growth factor (Fgf) 8 and Fgf 18, and FGFs can mimic some of the activities of the infundibulum. The requirement for FGF signaling during growth and patterning of the anterior pituitary has not, however, been established. By blocking FGF receptor signaling in explants of the anterior pituitary cultured in vitro we provide evidence that FGF signaling derived from the infundibulum is required for the proliferation and patterning of progenitor cells in the anterior pituitary.     

Oxysterol 7 alpha-hydroxylase activity by cholesterol 7 alpha-hydroxylase (CYP7A)

A 7 alpha-hydroxylation is necessary for conversion of both cholesterol and 27-hydroxycholesterol into bile acids. According to current theories, cholesterol 7 alpha-hydroxylase (CYP7A) is responsible for the former and oxysterol 7 alpha-hydroxylase (CYP7B) for the latter reaction. CYP7A is believed to have a very high substrate specificity whereas CYP7B is active toward oxysterols, dehydroepiandrosterone, and pregnenolone. In the present study, 7 alpha-hydroxylation of various oxysterols in liver and kidney was investigated. Surprisingly, human cholesterol 7 alpha-hydroxylase, CYP7A, expressed as a recombinant in Escherichia coli and COS cells, was active toward 20(S)-hydroxycholesterol, 25-hydroxycholesterol, and 27-hydroxycholesterol. This enzyme has previously been thought to be specific for cholesterol and cholestanol. A partially purified and reconstituted cholesterol 7 alpha-hydroxylase enzyme fraction from pig liver showed 7 alpha-hydroxylase activity toward the same oxysterols as metabolized by expressed recombinant human and rat CYP7A. The 7 alpha-hydroxylase activity toward 20(S)-hydroxycholesterol, 25-hydroxycholesterol, and 27-hydroxycholesterol in rat liver was significantly increased by treatment with cholestyramine, an inducer of CYP7A. From the present results it may be concluded that CYP7A is able to function as an oxysterol 7 alpha-hydroxylase, in addition to the previously known human oxysterol 7 alpha-hydroxylase, CYP7B. These findings may have implications for oxysterol-mediated regulation of gene expression and for pathways of bile acid biosynthesis. A possible use of 20(S)-hydroxycholesterol as a marker substrate for CYP7A is proposed.     

<Emphasis Type="Italic">TRAF1/C5</Emphasis>polymorphism is not associated with increased mortality in rheumatoid arthritis: two large longitudinal studies

Introduction  

Recently an association between a genetic variation in TRAF1/C5 and mortality from sepsis or cancer was found in rheumatoid arthritis (RA). The most prevalent cause of death, cardiovascular disease, may have been missed in that study, since patients were enrolled at an advanced disease stage. Therefore, we used an inception cohort of RA patients to investigate the association between TRAF1/C5 and cardiovascular mortality, and replicate the findings on all-cause mortality. As TRAF1/C5 associated mortality may not be restricted to RA, we also studied a large cohort of non-RA patients.