Insulin Prevents Hyperfiltration and Proteinuria but Not Glomerular Hypertrophy and Increases Mesangial Matrix Expansion in Diabetic Rats.

Objective: The aim of this work was to study the effect of 7 days of strict glycemic control with insulin on glomerular function and structure in streptozotocin (STZ)-diabetic rats.

Materials And Methods: Three groups of adult male Fischer rats were studied: controls (n = 15), diabetics (n = 15), and insulin-treated diabetics (n = 15). Diabetes was induced by treating the rats with STZ (55 mg/kg i.

Phlorizin prevents glomerular hyperfiltration but not hypertrophy in diabetic rats.

The relationships of renal and glomerular hypertrophies to development of hyperfiltration and proteinuria early in streptozotocin-induced diabetes were explored. Control, diabetic, phlorizin-treated controls, and diabetic male Fischer rats were used. Phlorizin (an Na+-glucose cotransport inhibitor) was given at a dose sufficient to normalize blood glucose.

Pulmonary ventilatory functions and obesity in Kuwait.

Objective: To study the relationship between obesity and pulmonary ventilatory functions in Kuwaiti adults.

Subjects And Methods: A total of 200 male and 180 female Kuwaiti adults aged 20-65 years were investigated in six medical centers from April 2004 to March 2006. Parameters measured included forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC), FEV(1) as a percentage of FVC (FEV%); body mass index (BMI in kg/m(2)) and waist-to-hip ratio (W/H).

Interactions of the growth-related, type IIc renal sodium/phosphate cotransporter with PDZ proteins.

Despite similar molecular structures, the growth-related sodium/phosphate cotransporter NaPiIIc is regulated differently than the main NaPiIIa phosphate transporter. Using two-hybrid systems and immunoprecipitation, we identified several proteins that interact with NaPiIIc that might account for this differential regulation. NaPiIIc interacted with the PDZ domain-containing sodium-hydrogen exchange-regulating factor (NHERF) 1 and NHERF3 through novel binding motifs in its C terminus.

Cell-matrix interactions modulate transepithelial phosphate transport in P(i)-deprived OK cells.

In opossum kidney (OK) cells as well as in kidney proximal tubules, P(i) depletion increases apical (A) and basolateral (B) Na(+)-dependent P(i) cell influxes. In OK cells' monolayers in contrast to proximal tubules, there is no increase in transepithelial P(i) transport. This limitation may be due to altered cell-matrix interactions.

Expression of the rat renal PiT-2 phosphate transporter.

Background: NaPi-2a is the main sodium-dependent Pi (Na+-Pi) transporter in the apical membrane of the renal proximal tubule. Another group of Pi transporters, Glvr-1 (PiT-1) and Ram-1 (PiT-2), was identified. The PiT-2 cRNA induces Na+-dependent Pi uptake into Xenopus laevis oocytes.

Parathormone sensitivity and responses to protein kinases in subclones of opossum kidney cells.

Parathyroid hormone (PTH) inhibits sodium-dependent phosphate (Na(+)-Pi) transport in the renal proximal tubule and opossum kidney (OK) cells by mechanisms involving protein kinases (PK) A and C, and 20-hydroxyeicosatetraneoic acid (20-HETE). The magnitude of the effect of PKA and PKC on Na(+)-Pi transport in OK cells varies in different studies, suggesting that OK cell subclones are functionally heterogeneous despite their morphological similarity. We studied the effect of PTH and PK effectors in two separate sets of OK cells at two different time periods.

Hypoxic rise in cytosolic calcium and renal proximal tubule injury mediated by a nickel-sensitive pathway.

In the kidney, cell injury resulting from ischemia and hypoxia is thought to be due, in part, to increased cytosolic Ca(2+) levels, [Ca(2+)]i, leading to activation of lytic enzymes, cell dysfunction, and necrosis. We report evidence of a progressive and exponential increase in [Ca(2+)]i (from 245 +/- 10 to 975 +/- 100 nM at 45 mins), cell permeabilization and propidium iodide (PI) staining of the nucleus, and partial loss of cell transport functions such as Na(+)-gradient-dependent uptakes of (14)C-alpha-methylglucopyranoside and inorganic phosphate ((32)Pi) in proximal convoluted tubules of adult rabbits subjected to hypoxia. The rise in [Ca(2+)]i depended on the presence of extracellular [Ca(2+)] and could be blocked by 50 microM Ni(2+)but not by verapamil (100 microM).

Reported frequency of physical activity, fitness, and fatness in Kuwait.

We studied reported frequency of physical activity (PA), body composition, and fitness in Kuwaiti females (n = 84) and males (n = 72), urban office government employees, or students. A sedentary (SED) group reported no or occasional participation in self-directed PA of 30 minutes or more during the week for the last 6 months; group LOF (low frequency) participated in 1-2 sessions/week (walking, jogging, sports such as volleyball, soccer, or gym); group HIF (higher frequency) reported three or more sessions/week. Aerobic fitness was measured using Bruce's treadmill protocol.

Basolateral phosphate transport in renal proximal-tubule-like OK cells.

It is generally assumed that phosphate (Pi) effluxes from proximal tubule cells by passive diffusion across the basolateral (BL) membrane. We explored the mechanism of BL Pi efflux in proximal tubule-like OK cells grown on permeable filters and then loaded with 32P. BL efflux of 32P was significantly stimulated (P < 0.

Gastrointestinal parasitic infection, anthropometrics, nutritional status, and physical work capacity in Colombian boys.

This article tests the hypothesis that the presence of gastrointestinal parasites in Colombian boys is negatively associated with anthropometric characteristics, physical work capacity, blood hemoglobin (Hb) levels, and nutritional status. Anthropometric, Hb, &Vdot;O(2) max, and parasite load data were collected on 1,016 boys in Cali, Colombia. The boys were classified as lower socioeconomic class (SEC) from either urban or rural environments, and upper SEC from an urban environment.

Cardio-respiratory responses to moderately heavy aerobic exercise during the Ramadan fasts.

Objective: The aim of this study was to quantify the magnitude of the cardiovascular and respiratory changes that occur during the month of Ramadan in response to moderately heavy aerobic physical exertion.

Methods: Eighteen sedentary Kuwaiti adult males were tested under thermo-neutral conditions during a spring-like month of Ramadan and one month thereafter.

Results: There were no significant changes in maximal exercise capacity, treadmill walking efficiency, percentage VO2 max, in body weight and composition associated with Ramadan fasting or one month after.

Ontogeny of renal phosphate transport and the process of growth.

The kidneys of infants and children reabsorb a high fraction of the filtered phosphate (Pi), as appropriate to the needs of a growing organism. This high Pi reabsorptive rate is associated with a high capacity (Vmax) of the Na+-Pi symport system. At the molecular level this high reabsorptive capacity appears to be due to the presence of a growth-specific Na-Pi cotransporter.

Phosphate depletion in opossum kidney cells: apical but not basolateral or transepithelial adaptions of Pi transport.

Monolayers of opossum kidney (OK) cells are widely used as models for the renal proximal tubule. OK cells adapt to phosphate (Pi) depletion by increasing their capacity for apical and basolateral Na+-dependent Pi uptake. Because NMR-visible cell Pi was found to be decreased in Pi-deprived kidney cells, we suggested that up-regulation of basolateral Pi efflux also occurs during adaptation to Pi deprivation [American Journal of Physiol 1994;267:C915-919].

Low-frequency physical activity insufficient for aerobic conditioning is associated with lower body fat than sedentary conditions.

We aimed to show the relationships between reported physical activity, fitness level, and body composition in healthy adult office-working Kuwaiti males (n = 45). Reported level of physical activity (group 0 = no routine exercise, n = 10; group 1 = routine exercise once per wk, n = 19; group 2 = routine exercise two or more times per wk, n = 16) was determined from recall questionnaires. Aerobic fitness levels were assessed from resting exercise heart rates and measurement of maximal oxygen uptake (treadmill exercise, Bruce protocol).

Hormonal regulation of sodium-dependent phosphate transport in opossum kidney cells.

There are multiple regulators of renal proximal tubule sodium-dependent phosphate (Na(+)-Pi) transport, including 1,25-dihydroxyvitamin D (1,25-Vit. D), parathyroid hormone (PTH), insulin-like growth factor 1 (IGF-1), and arachidonic acid (AA) and/or its metabolites. The purpose of our studies was to determine whether the effect of these factors on Pi transport is synergistic or antagonistic.

Multiple arachidonic acid metabolites inhibit sodium-dependent phosphate transport in OK cells.

The cytochrome P450-dependent monoxygenase pathway represents a major route for the metabolism of arachidonic acid (AA) in the kidney. In turn, AA metabolites have been shown to affect renal electrolyte metabolism, including sodium transport. Specifically AA, 20-HETE and 12-HETE inhibit sodium-dependent (Na+-Pi) uptake into renal culture cells, and both 12-HETE and 14,15 EET have been shown to reduce renin release from renal cortical slices.

Responses to exercise, fluid, and energy balances during Ramadan in sedentary and active males.

This study compares the effects of the Ramadan fast (RF) on body and plasma compositions, hematology, and responses to steady state submaximal exercise in six physically active (A, 35.5+/-1.6 y) and seven sedentary (S, 37.

Study of renal metabolic disturbances related to renal lithiasis at school age in very-low-birth-weight children.

We studied 34 asymptomatic children who were born with a very-low-birth-weight (VLBW) and had no perinatal history of acute renal failure nor treatment with furosemide. The study was done at preschool or school age, looking for echographic changes and renal tubular disturbances which are known to predispose to renal lithiasis. The results were compared with those of a control group of 18 children who had been born at term with a body weight >2,500 g.

20-HETE mediates the effect of parathyroid hormone and protein kinase C on renal phosphate transport.

Parathyroid hormone (PTH) is a major inhibitor of renal proximal tubule (PT) sodium-dependent phosphate (Na+-Pi) cotransport. PTH is thought to exert its effect on Pi transport in the PT via the protein kinase A (PKA) and C (PKC) intracellular signalling pathways. PKC-dependent phosphorylation of phospholipase A2 stimulates arachidonic acid (AA) release, the latter a potent inhibitor of Pi transport.

A putative growth-related renal Na(+)-Pi cotransporter.

The mRNA that encodes for NaPi-2, the renal Na(+)-Pi cotransporter that is upregulated by Pi depletion in the adult rat, is low in the young animal. Yet, renal Na-Pi cotransport rates are higher in rapidly growing than in fully grown rats. The aim of this study was to unravel the molecular basis of this apparent discrepancy.

Renal protein degradation in streptozotocin diabetic mice.

In diabetes mellitus, the kidney and the gut--but not the liver or the muscle--undergo hypertrophy. Hypertrophy may be due to an increase in the rate of protein synthesis and/or to a decrease in proteolysis. In order to resolve this issue we assessed in vivo the rates of protein degradation by measuring the disappearance rates of 3H- and 14C-labelled valine incorporated into renal and liver proteins of control and streptozotocin-diabetic mice.

Age dependence of tolerance to anoxia and changes in cytosolic calcium in rabbit renal proximal tubules.

Calcium(Ca2+)-dependent processes mediate, in part, anoxic cell injury. These may account for the difference in sensitivity to anoxia between certain immature and mature renal cells. To address this question, we studied the effects of anoxia on cytosolic free Ca2+ concentration ([Ca2+]i), cell integrity, and transport functions in microdissected proximal convoluted tubules (PCT) of < 3-week-old (newborn) and > 12-week-old (adult) rabbits.

Mechanism of renal phosphate retention during growth.

We have previously demonstrated that the retention of phosphate required for growth is due to a a high Vmax of the Na(+)-Pi cotransport system located in the brush border membrane of the proximal tubule. Because of this and other similarities between adaptation of the kidney to a high Pi demand (growth) and that to low Pi supply, we measured the levels of NaPi-2 mRNA and cDNA present in kidney cortex of 3- and > 12-week-old rats. Like in Pi depletion, Western blots revealed that a 80 to 85 kDa protein recognized by a polyclonal antibody directed against the N-terminal region of the NaPi-2 protein was 2.

Use of proton MR spectroscopy and MR imaging to assess obesity.

We used 1H MR spectroscopy and MR imaging at 9.4-T to quantify and localize fat and water in the abdominal regions of 12 lean, normal, and obese mice. The D2O dilution method which measures also the equilibrium plasma D2O concentration by 2H MR spectroscopy was used to quantify body water and fat.