Relationships between three potentiation effects of plyometric training and performance.

UNLABELLED: This study measured the potentiation effects of plyometric training [normalized electromyography (EMG) in triceps surae, stiffness and elastic energy utilization of the Achilles tendon] and investigated the correlations between these effects and performances [voluntary electromechanical delay (EMD) and jump height]. Twenty-one subjects were randomly assigned either to the control group (10 subjects: age 22.3+/-1.6 years) or to a training group (11 subjects: age 22.1+/-1.6 years) that performed 8 weeks of plyometric training. RESULTS: As compared with the performances before training, normalized EMG in the soleus were significantly (P

Inhibition of collagen fibril formation in vitro and subsequent cross-linking by glucose.

Glucose inhibits collagen fibril formation in vitro. A linear dose response was observed, with half-maximum inhibition of fibril formation occurring at 50 mM glucose. Nonfibrillar collagen cannot be cross-linked by lysyl oxidase, an enzyme that catalyzes the initial cross-linking reaction. The degree of decreased fibril formation correlated with the loss of ability of the collagen to serve as a substrate for lysyl oxidase. Collagen that is not cross-linked is unstable and more susceptible to collagenolytic attack. Interference with collagen cross-linking and more rapid degradation may explain the decreased amounts of interstitial collagen and the poor healing of wounds associated with diabetes mellitus.

Role of organic osmolytes in myelinolysis. A topographic study in rats after rapid correction of hyponatremia.

Organic osmolytes have been implicated in the pathogenesis of myelinolysis because some of them are accumulated slowly during correction of chronic hyponatremia. I investigated whether there was a topographic correlation between demyelinative lesions and the regional changes of organic osmolytes after rapid correction of chronic hyponatremia. In normal female Sprague-Dawley rats, concentrations of glutamate, glutamine, taurine, and betaine were highest in the cerebral cortex and decreased toward the brain stem. Conversely, glycine level was highest in the brainstem, and decreased toward the cortex. Myoinositol, glycerophosphorylcholine, glycerophosphorylethanolamine, and creatine were distributed more evenly. In chronic hyponatremic rats (plasma Na 110 +/- 4 meq/liter), organic osmolytes decreased globally with the total loss ranging from 13 (medulla) to 24 (cerebellum) mmol/kg H2O. After rapid correction with intraperitoneal injection of hypertonic saline, the recovery of the loss of organic osmolytes was 48% in the cerebral cortex, cerebellum, and medulla oblongata, 44% in pons, but only 17% in midbrain and 36% in striatum. Histopathology of the brain was examined in nine rats 2-7 d after correction of hyponatremia. Large demyelinative lesions were seen persistently in the midbrain and striatum, and smaller lesions in cerebrum, cerebellum, and pons were found less frequently. This is the first report of regional distribution of brain organic osmolytes. After rapid correction of chronic hyponatremia, a topographic correlation between demyelination lesions and delayed accumulation of organic osmolytes exists.

Effects of hypernatremia on organic brain osmoles.

We studied the effects of varying degrees and durations of hypernatremia on the brain concentrations of organic compounds believed to be important, so-called "idiogenic" osmoles in rats by means of conventional biochemical assays, nuclear magnetic resonance spectroscopy, and high-performance liquid chromatography. There were no changes in the concentrations of these osmoles (specifically myoinositol, sorbitol, betaine, glycerophosphorylcholine [GPC], phosphocreatine, glutamine, glutamate, and taurine) in rats with acute (2 h) hypernatremia (serum Na 194 +/- 5 meq/liter). With severe (serum Na 180 +/- 4 meq/liter) chronic (7 d) hypernatremia, the concentrations of each of these osmoles except sorbitol increased significantly: myoinositol (65%), betaine (54%), GPC (132%), phosphocreatine (73%), glutamine (143%), glutamate (84%), taurine (78%), and urea (191%). Together, these changes account for 35% of the change in total brain osmolality. With moderate (serum Na 159 +/- 3 meq/liter) hypernatremia, more modest but significant increases in the concentrations of each of these osmoles except betaine and sorbitol were noted. When rats with severe chronic hypernatremia were allowed to drink water freely, their serum sodium as well as the brain concentrations of all of these organic osmoles except myoinositol returned to normal within 2 d. It is concluded that: idiogenic osmoles play an important role in osmoregulation in the brain of rats subjected to hypernatremia; the development of these substances occur more slowly than changes in serum sodium; and the decrease in concentration of myoinositol occurs significantly more slowly than the decrease in serum sodium which occurs when animals are allowed free access to water. These observations may be relevant to the clinical management of patients with hypernatremia.

Study of brain electrolytes and organic osmolytes during correction of chronic hyponatremia. Implications for the pathogenesis of central pontine myelinolysis.

Osmotic injury induced by rapid correction of severe chronic hyponatremia has been implicated in the development of central pontine myelinolysis. Organic osmolytes known previously as "idiogenic osmoles" accumulate intracellularly to protect cells from osmotic injury. We investigated the changes of these organic osmolytes as well as electrolytes in the brain during the induction and correction of chronic hyponatremia. Using 1H-nuclear magnetic resonance spectroscopy and HPLC, we found that in rats with chronic hyponatremia (3 d, serum sodium = 109 +/- 3 meq/liter), brain concentrations of myoinositol (41%), glycerophosphorylcholine (45%), phosphocreatine/creatine (60%), glutamate (53%), glutamine (45%), and taurine (37%) were all significantly decreased compared with control values (percentage control value shown, all P less than 0.01). The contribution of measured organic osmolytes and electrolytes to the total brain osmolality change was 23 and 72%, respectively. With rapid correction by 5% NaCl infusion, significant brain dehydration and elevation of brain Na and Cl levels above the normal range occurred at 24 h. These changes were not seen with slow correction by water deprivation. Reaccumulation of most organic osmolytes except glycerophosphorylcholine is delayed during the correction of hyponatremia and is independent of the correction rate of serum sodium. It is concluded that: most of the change of brain osmolality in chronic hyponatremia can be accounted by the changes in organic osmolytes and brain electrolytes; and rapid correction of hyponatremia is associated with an overshoot of brain sodium and chloride levels along with a low organic osmolyte level. The high cerebral ion concentrations in the absence of adequate concentrations of organic osmolytes may be relevant to the development of central pontine myelinolysis.

Hemodialysis increases apparent diffusion coefficient of brain water in nephrectomized rats measured by isotropic diffusion-weighted magnetic resonance imaging.

The nature of brain edema in dialysis disequilibrium syndrome (DDS) was investigated by diffusion-weighted magnetic resonance imaging (DWI). DWI was performed on normal or bilaterally nephrectomized rats before, and immediately after, hemodialysis. Hemodialysis was performed with a custom-made dialyzer (surface area 150 cm2) against a bicarbonate-buffered bath for 90 min with or without 70 mM urea. Hemodialysis with non-urea bath decreased plasma urea by 21 mM, and plasma osmolality by 22 mosmol/kg H2O, and increased brain water content by 8.0% (all < 0.05), while hemodialysis with urea bath did not affect plasma urea, osmolality, or brain water content. Three sets of axial DWI images of the brain were obtained at different gradient weighing factors with an in-plane resolution of 0.39 mm2. The apparent diffusion coefficient (Dapp) of the brain water was not affected by bilateral nephrectomy, or by hemodialysis in normal rats. In nephrectomized rats, brain Dapp was significantly increased after dialysis with non-urea bath (1.15 +/- 0.08 vs 0.89 +/- 0.07 x 10(-9)m2/sec, P < 0.01). No significant changes of brain water Dapp could be observed after dialysis with urea bath. The increased Dapp associated with DDS indicates that brain extracellular water increases and/or intracellular water decreases after hemodialysis. Our results strongly suggest that the brain edema induced by hemodialysis in uremic rats is due to interstitial edema rather than cytotoxic edema. Furthermore, our results support a primary role for the "reverse urea effect" in the pathogenesis of brain edema in DDS.DWI may be a useful diagnostic tool for DDS in patients with end-stage renal disease.

Correction of renal tubular acidosis in carbonic anhydrase II-deficient mice with gene therapy.

Carbonic anhydrase II (CAII) deficiency in humans is associated with a syndrome of renal tubular acidosis, osteopetrosis, and cerebral calcification. A strain of mice of CAII deficiency due to a point mutation also manifests renal tubular acidosis. We report here that retrograde injection of cationic liposome complexed with a CAII chimeric gene, using a cytomegalovirus (CMV) promoter/enhancer as an expression cassette to drive human CAII cDNA, into the renal pelvis of CAII-deficient mice results in expression of CAII in the kidney. The levels of both the CAII gene and its corresponding mRNA were highest by day 3 after treatment, diminishing thereafter, but remaining detectable by 1 mo. After gene therapy, CAII-deficient mice restored the ability to acidify urine after oral administration of ammonium chloride. The ability to acidify urine was maintained at 3 wk after gene therapy, and was eventually lost by 6 wk. Immunohistochemistry studies using anti-CAII antibodies showed that CAII was expressed in tubular cells of the outer medulla and corticomedullary junction. The gene therapy was not associated with nephrotoxicity as assessed by blood urea nitrogen levels and renal histology. To our knowledge, this is the first successful gene therapy of a genetic renal disease. Our results demonstrate the potential of gene therapy as a novel treatment for hereditary renal tubular defects.

Chemical size effect on the magnetic and electrical properties in the (Tb(1-)(x)Eu(x))MnO(3) (0 < or = x < or = 1.0) system.

The effect of isovalent chemical substitution of Eu3+ into the Tb3+ sites on the magnetic and electrical properties of (Tb1-xEux)MnO3 (0

Effects of a structured exercise programme in sedentary dogs with chronic diarrhoea.

The aim of this investigation was to evaluate the effects of a structured exercise programme in sedentary dogs with chronic diarrhoea. Twenty-two dogs were enrolled in the study. All dogs received oral prednisolone (1 mg/kg/day for 14 days, followed by a tapering dosage) for 10 weeks. After four weeks of prednisolone treatment, dogs were assigned to either the exercise or control group (n=11 each). Owners of dogs in the exercise group were instructed to guide their dogs in structured exercise training (low-intensity to moderate-intensity aerobic and resistance exercise three to five days per week). After 10 weeks of prednisolone treatment with concomitant 6 weeks of complementary exercise, the Canine Inflammatory Bowel Disease Activity Index (CIBDAI) score had decreased significantly in the exercise group (from 8.8±1.5 at the start of the exercise programme to 2.4±1.5; P<0.001); no such change was observed in the control group (from 9.2±0.9 to 9.2±1.1). CIBDAI scores differed significantly between the groups at the end of the 10-week study period (P<0.001). The exercise programme affected all six CIBDAI parameters significantly; bodyweight (P<0.001, adjusted r2=0.722) was most affected. A structured exercise programme may have positive effects on clinical symptoms in sedentary dogs with chronic diarrhoea.

A portable magneto-optical trap with prospects for atom interferometry in civil engineering.

The high precision and scalable technology offered by atom interferometry has the opportunity to profoundly affect gravity surveys, enabling the detection of features of either smaller size or greater depth. While such systems are already starting to enter into the commercial market, significant reductions are required in order to reach the size, weight and power of conventional devices. In this article, the potential for atom interferometry based gravimetry is assessed, suggesting that the key opportunity resides within the development of gravity gradiometry sensors to enable drastic improvements in measurement time. To push forward in realizing more compact systems, techniques have been pursued to realize a highly portable magneto-optical trap system, which represents the core package of an atom interferometry system. This can create clouds of 107 atoms within a system package of 20 l and 10 kg, consuming 80 W of power.This article is part of the themed issue 'Quantum technology for the 21st century'.

Observing coherence effects in an overdamped quantum system.

It is usually considered that the spectrum of an optical cavity coupled to an atomic medium does not exhibit a normal-mode splitting unless the system satisfies the strong coupling condition, meaning the Rabi frequency of the coherent coupling exceeds the decay rates of atom and cavity excitations. Here we show that this need not be the case, but depends on the way in which the coupled system is probed. Measurements of the reflection of a probe laser from the input mirror of an overdamped cavity reveal an avoided crossing in the spectrum that is not observed when driving the atoms directly and measuring the Purcell-enhanced cavity emission. We understand these observations by noting a formal correspondence with electromagnetically induced transparency of a three-level atom in free space, where our cavity acts as the absorbing medium and the coupled atoms play the role of the control field.

Collagen, proteoglycan and hyaluronidase activity in cultures from normal and scoliotic chicken fibroblasts.

Connective tissue matrix components were investigated using skin fibroblasts from normal or inbred scoliotic lines of chickens. Specifically, the fibroblasts were obtained from either an isogenic line or a backcross, derived by crossing the isogenic line with a pure line of scoliotic birds. From the backcross, both affected (35-45%) and non-affected (55-65%) progeny were produced. The affected birds had spinal curves greater than 20 degrees. Several abnormalities of connective tissue were observed when cells from scoliotic chicks were grown in culture: increased collagen extractability, decreased aggregatability of proteoglycans under associative conditions and lower than normal levels of hyaluronic acid. There was also less collagen deposited in the cell layer with proportionately increased amounts of collagen secreted into the culture media by cells from scoliotic versus normal chick fibroblasts. Values for collagen matrix stability, as estimated by extractability and net deposition, were intermediate for cells from the backcrossed, but non-affected, birds. Moreover, hyaluronidase, an enzyme that degrades hyaluronic acid, was abnormally elevated in the fibroblast cultures from scoliotic chicks. It is proposed that the increase in hyaluronidase contributes to the abnormalities observed in extracellular matrix components and may be a factor in the expression of scoliosis in susceptible birds.

In vivo 31P NMR study of early cellular responses to hyperosmotic shock in cultured glioma cells.

Cell volume regulation in the face of osmotic stress is a fundamental homeostatic activity, and is most critical in brain, which is spatially constrained. Despite the importance of this phenomenon, little is known about volume regulation in the brain, primarily because of the cellular heterogeneity in the tissue. We describe here simultaneous in vivo 31P nuclear magnetic resonance (NMR) measurements of cell volume, intracellular pH and phosphate metabolites during early responses to hyperosmotic stress in C6 glioma cells perfused in NMR-compatible bioreactors. Cell volume was measured using dimethyl methylphosphonate (DMMP) as a probe which has an intracellular NMR resonance shifted upfield from the extracellular resonance. The sensitivity of these measurements allowed 31P NMR spectra to be collected every 30 s. Following an increase in osmolarity from 320 to 480 mOsm by addition of NaCl to the perfusate, C6 glioma cells shrank to 67% of their original volume. We also observed a simultaneous increase of intracellular pH coincident with the decrease in cell volume. The signals from ATP decreased by 10%, but those from phosphocreatine (PCr) increased by 31% after hyperosmotic shock. However, correcting the ATP signals for the decrease in cell volume indicated that its intracellular concentrations increased after treatment. Signals from glycerophosphorylcholine (GPC) and glycerophosphorylethanolamine (GPE) were not changed significantly. This is the first in vivo report of early cellular responses monitored by NMR spectroscopy following hyperosmotic shock in cultured cells.

Long-term cyclophosphamide treatment for recurrent type I membranoproliferative glomerulonephritis after transplantation.

The incidence of recurrent type I membranoproliferative glomerulonephritis (MPGN) after renal transplant is approximately 30%, and the rate of graft loss due to recurrent MPGN type I is higher than 50%. The treatment of this disease has not been defined. We report a case of recurrent MPGN type diagnosed 4 months after a cadaveric renal transplantation. The patient was treated with cyclophosphamide and was able to maintain her graft function. Cyclophosphamide was interrupted three times during the course. Each time her renal function deteriorated and her serum albumin decreased. The patient currently has a functional renal graft 3 years after transplantation while receiving low-dose therapy with cyclophosphamide. We suggest treating recurrent type I MPGN with cyclophosphamide while continuing the calcineurin inhibitor and prednisone.

Therapeutic application of chimeric RNA/DNA oligonucleotide based gene therapy.

Chimeric RNA/DNA oligonucleotides, or chimera, have emerged as a breakthrough technology for treating genetic disorders. Chimera have been shown to induce correction of point mutations in several genetic disease models without utilising the viral vectors. Recent studies of chimera-based gene therapy in genetic disease models are reviewed. Chimera were delivered intravenously, intramuscularly, intradermally, or topically with or without vehicles. Correction of the mutation at genotypic and phenotypic levels was assessed using various methods. The gene correction frequency varied, ranging from 1-40%. The resulting phenotype changes lasted longer than one year in some studies. The most dramatic phenotypic change is the reduction of serum bilirubin level by 50% in the Gunn rat, a model for Crigler-Najjar syndrome. Chimera based gene therapy has the potential to develop into powerful therapeutic modality for genetic diseases.

Gene therapy for renal diseases.

Gene therapy is a promising therapeutic approach for a variety of renal diseases including both inherited and acquired diseases. In vivo gene transfer in the kidney using viral or non-viral vectors have been reported. These approaches have been tested in a few animal models of renal diseases, including experimental glomerulonephritis, ischemic renal failure, and carbonic anhydrase II deficiency. Selection of vectors, routes, and therapeutic genes is critical to the success of gene therapy targeted to the specific compartment of the kidney. Limitations of gene therapy for renal diseases exist and consist of: duration of transgene expression is short, transfection efficiency is not adequate, immune reactions are induced by adenoviral vector, and insertional mutagenesis may be caused by retroviral and adeno-associated viral vectors. Further studies are needed for improvement of gene delivery, minimization of side effects and development of cell-specific and long-term regulated gene expression.

Scyllo-inositol depletion in hepatic encephalopathy.

Cerebral myo-inositol depletion is found in patients with hepatic encephalopathy and can be implicated in the pathogenesis of hepatic encephalopathy. We measured scyllo-inositol, a stereoisomer of myo-inositol, in brain extracts from patients dying in hepatic coma using HPLC and high resolution 1H MRS. The cerebral scyllo-inositol concentration, determined by both methods, in patients without hepatic encephalopathy was 0.41 +/- 0.11 mmol/kg wet weight. It decreased by 73% and 76%, respectively, as measured by HPLC and 1H MRS, in patients with hepatic encephalopathy. These findings indicate that myo-inositol depletion in patients with hepatic encephalopathy is not due to enhanced conversion of myo-inositol to scyllo-inositol or inhibition of myo-inositol transport by scyllo-inositol, but rather to the reduced biosynthesis or transport of both inositols.

Promoter activity of carbonic anhydrase II regulatory regions in cultured renal proximal tubular cells.

Carbonic anhydrase II (CAII) plays an important role in the acid-base homeostasis of the body and its deficiency results in renal tubular acidosis. In order to identify the regulatory regions in the CAII gene for the future development of kidney-targeted gene therapy, we investigated the 5' region of the gene for its promoter activity. Deletion constructs with various lengths of the 5' flanking region of the human CAII promoter were ligated to the CAT reporter gene and lipofected in primary cultures of mouse proximal renal tubular cells and in cells of the established porcine proximal tubular cell line, LLC-PK1. The CAT activity was measured 48 hours after gene transfection. The -12000/CAT and -1300/CAT constructs expressed the highest CAT activity in both types of renal tubular cells (143- and 180-fold increase, respectively, in mouse proximal tubular cells; 50- and 70-fold increase, respectively, in LLC-PK1 cells) but not the -420/CAT, -270/CAT, or -180/CAT constructs (9, 12, and 9% of that of -1300/CAT construct, respectively, in mouse proximal tubular cells and, 23, 9, and 8%, respectively, in LLC-PK1 cells, all p <0.01 vs. -1300/CAT construct). No cytotoxicity was detected in the transfected cells. A computer search identified multiple putative transcription factor binding elements including Ap1 and Ap2 binding elements, which are present in the -1300/CAT construct but not in the shorter constructs. In conclusion, we demonstrate that the human CAII 5' sequence of proximal 1.3 kb contains strong promoter sequence(s) for renal tubular cells.

Renal gene therapy.

Until now there is no renal gene therapy available for clinical use, however, gene therapy for several experimental renal diseases has been tested with promising results. The kidney is a well-differentiated organ with a variety of specialized compartments, i.e., vascular, glomerular, tubular, and interstitial. Many physiological factors such as cell turnover rate, blood flow, and urine flow, as well as anatomical factors such as glomerular basement membrane and nephron segment arrangement, may affect the specificity and efficacy of gene therapy in the kidney. On the other hand, the kidney has a major advantage over other solid organs, since it is accessible by many routes, including intrarenal artery infusion, retrograde delivery through the urinary tract, direct injection into renal parenchyma, and perfusion into the donor graft prior to transplantation (1). This chapter reviews nonviral gene transfer in the different compartments of the kidney (for review of viral vectormediated renal gene transfer, see refs. 2-5), and in skeletal muscle, for renal gene therapy, and potential applications and safety concerns for renal gene therapy.

Low dose megestrol increases serum albumin in malnourished dialysis patients.

To evaluate the efficacy of low dose megestrol on malnourished dialysis patients we treated 16 dialysis patients with persistent hypoalbuminemia ( < 3.5 gm/dl for 2 consecutive months) and adequate dialysis at a dose of 20 mg orally twice daily. Twelve patients on peritoneal dialysis and 4 on hemodialysis were followed for 4.3 +/- 0.6 m (2-11 m). Within one month serum albumin rose from 2.7 +/- 0.1 to 3.0 +/- 0.2 gm/dl (p < 0.05) and remained elevated at the end of follow-up (3.1 +/- 0.2, p < 0.05 vs. pre-treatment levels). In the 12 responders (increase of albumin > 0.3 gm/dl), all of whom reported improved appetite, the maximal increase of serum albumin in 2 months was 0.8 +/- 0.1 gm/dl (range: 0.3-1.2). Four patients did not respond (change of albumin: -0.05 +/- 0.18, range: -0.6-0.2) because of encephalopathy, amyloidosis, depression or noncompliance. One patient stopped megestrol because of vaginal bleeding from uterine leiomyoma. Three patients died from causes unrelated to the megestrol. Our preliminary study suggests that low dose megestrol (40 mg per day) increases serum albumin levels in 75% of dialysis patients with malnutrition. It is well tolerated but may cause vaginal bleeding from uterine tumors.