Increased renal medullary endothelin-1 synthesis in prehypertensive DOCA- and salt-treated rats

To investigate the role of renal endothelin-1 (ET-1) synthesis in water-sodium homeostasis, we measured mRNA expressions, protein levels, enzyme activity, and receptor binding of the renal ET-1 system in a DOCA- and salt-treated rat model. Male Wistar rats were divided into control and DOCA- and salt-treated (DOCA-Salt) groups. The DOCA-Salt group received 25 mg/kg body wt DOCA and was maintained on 1% NaCl drinking water. Rats were killed on days 1, 2, 4, and 10 of the experiment. Urinary ET-1-like immunoreactivity significantly increased from the second day in the DOCA-Salt group and correlated well with the urinary sodium excretion rate (r = 0.81, P < 0.001). Renal endothelin-converting enzyme (ECE) activity, ET-1, and ECE-1 mRNA expressions were significantly increased in the renal medullary area of DOCA-Salt rats. In situ hybridization and immunohistochemical studies showed that the increase in ET-1 synthesis was mainly localized in the inner medullary collecting ducts. The maximum binding of endothelin B receptor also increased from the second day in the renal medulla of the DOCA-Salt group. Our results suggest that renal medullary synthesized ET-1 may be a natriuretic factor and may participate in the intrarenal regulation of water and salt homeostasis in prehypertensive DOCA-and salt-treated rats.

In vivo effect of endothelin-1 on plasma calcium and parathyroid hormone concentrations

We have previously reported an in vitro inhibitory effect of endothelin-1 (ET-1) on parathyroid hormone (PTH) secretion. In the present experiment, ET-1 was infused into rabbits to study the in vivo effect of ET-1 on the changes in calcium, magnesium, PTH and calcitonin concentrations. Femoral arteries and veins of anesthetized male rabbits were cannulated to monitor vital signs, blood sampling and infusion of the agents being studied. Infusion of ET-1 (1, 5, 10 and 20 ng/kg per min) induced a dose-dependent decline in plasma ionized calcium concentrations from 6.68+/-0.26 to 5.50+/-0.46 mg/dl (P<0.05) and a decrease in calcitonin concentrations from 48.6+/-6.5 to 32.5+/-4.7 pg/ml. PTH concentrations increased from 58.3+/-10.2 to 159.4+/-22.1 pg/ml. In a separate experiment, calcium gluconate solution was simultaneously infused to keep calcium concentrations steady, thereby proving a calcium 'clamp'. In normal calcium concentration, ET-1 infusion gradually decreased PTH concentrations from 71.4+/-8.6 to 38.0+/-6.2 pg/ml. We further infused sodium citrate solution to decrease the calcium concentration (2.0 mg/dl less) and calcium gluconate solution was infused to keep calcium concentrations steadily less than normal. PTH concentrations were initially stimulated by the induction of hypocalcemia (68.1+/-11.2 to 135.6+/-8.5 pg/ml), but decreased by ET-1 infusion (135.6+/-8.5 to 85.1+/-15.2 pg/ml). Plasma magnesium concentrations did not change significantly throughout the entire study and calcitonin concentrations were not significantly changed during the calcium clamp studies. Serum phosphate and 1,25-(OH)(2) vitamin D(3) concentrations were also measured, but they also did not change significantly. In conclusion, ET-1 exhibited an in vivo acute hypocalcemic action, independent of calcitonin. It also directly decreased PTH secretion if serum calcium concentrations were kept steady. The above findings are consistent with the results of our previous in vitro experiment.

Reactive oxygen species enhances endothelin-1 production of diabetic rat glomeruli in vitro and in vivo

Both reactive oxygen species (ROS) and endothelin-1 (ET- 1) have been implicated in the pathophysiology of diabetic nephropathy. The interrelationship between them, however, has not been documented in this disease. To determine whether ROS regulates ET-1 production in diabetic kidneys, we examined the in vitro and in vivo effects of ROS donors and scavengers on ET-1 production of diabetic rat glomeruli. For in vitro study, the glomeruli were isolated with a sieving method from streptozotocin-induced diabetic rats and killed at 1 week, 1 month, and 3 months, respectively. Superoxide was measured by a spectrophotometer, and ET-1 was measured by radioimmunoassay. The results demonstrated that the basal production levels of superoxide and ET-1 were higher in diabetic glomeruli than in normal glomeruli in vitro. There was a positive correlation between the production of superoxide and ET-1 in diabetic glomeruli. The basal ET-1 production was markedly attenuated by ROS scavengers including superoxide dismutase, catalase, dimethyl sulfoxide, and deferoxamine in diabetic glomeruli. Exogenous ROS generated by xanthine/xanthine oxidase significantly enhanced ET-1 generation by both diabetic and normal glomeruli. A high glucose concentration (500 mg/dL) in vitro increased ET-1 production by normal glomeruli but not diabetic glomeruli, and insulin partly suppressed ET- 1 production by diabetic glomeruli. The in vivo study demonstrated that when diabetic rats were injected daily with superoxide dismutase or catalase after diabetes was induced, the basal production of ET-1 was markedly attenuated after 1 week and 1 month, respectively. These results indicate that exogenously or endogenously derived ROS can enhance ET-1 production by diabetic rat glomeruli and that ROS scavengers suppress ET- 1 production both in vitro and in vivo. The effects of ROS on ET-1 production of diabetic glomeruli may be partly caused by the effect of hyperglycemia or insulin deficiency.

Flavonol-cinnamate cycloadducts and diamide derivatives from Aglaia laxiflora

Leaf extracts of the Malaysian plant Aglaia laxiflora provided two cytotoxic compounds, a new rocaglaol rhamnoside (1), a known rocaglaol (2), new (but inactive) flavonol-cinnamaminopyrrolidine adducts (3-6), and their probable biosynthetic precursors (7 and trimethoxyflavonol). All structures were elucidated primarily by 2D NMR spectroscopy. The structure and stereochemistry of aglaxiflorin A (3) were confirmed by single-crystal X-ray crystallography.

Fatal outcome after ingestion of star fruit (Averrhoa carambola) in uremic patients

Clinical outcome of dialysis patients after eating star fruit (Averrhoa carambola) varies, but it may be fatal. In the past 10 years, 20 such patients were treated in our hospital when they developed clinical symptoms after eating the fruit or drinking star fruit juice. Their initial presentations included sudden-onset limb numbness, muscle weakness, intractable hiccups, consciousness disturbance of various degrees, and seizure. No other major events that might be responsible for these symptoms could be identified. Eight patients died, including one patient with a serum creatinine level of 6.4 mg/dL who had not yet begun dialysis. The clinical manifestations of the survivors were similar to those who died except for consciousness disturbance and seizure. Death occurred within 5 days despite emergent hemodialysis and intensive medical care. The survivors' symptoms usually became less severe after supportive treatment, and these patients subsequently recovered without obvious sequelae. The purpose of this article is to report that patients with renal failure who ingest star fruit may develop neurological symptoms and also run the risk for death in severe cases. Mortality may also occur in patients with chronic renal failure not yet undergoing dialysis.

Antibiotic treatment of orbital cellulitis: an analysis of pathogenic bacteria and bacterial susceptibility

The proper choice of effective antibiotics is a mainstay for the treatment of orbital cellulitis. The lack of native data regarding the microorganism causing the infection and its antibiotic sensitivity prompted us to conduct this study. We retrospectively collected 29 cases of orbital cellulitis admitted to Chung-Ho Memorial Hospital of Kaohsiung Medical College from January 1994 to September 1998. The effectiveness of antibiotics with bacterial susceptibility was analyzed. Of the 29 cases, fifteen were male and fourteen female. The patients ranged in age from 7 months to 79 years (mean, 37.6 years). Sinusitis (9 cases, 31.0%) is the most common etiology. Fourteen cases received both medical and surgical treatments. Eighteen cases had purulent discharge from the infection areas sent for culture isolation of the microorganism. The culture positive rate was 50% (9 in 18 cases). The Staphylococcus aureus (5 cases) was the most common pathogen. The bacterial susceptibility test showed drug resistance of 100% for penicillin G (seven out of seven cases; 7/7), 100% for ampicillin (10/10), and 0% for amikacin (0/3) and vancomycin (0/7). Penicillin and ampicillin are not effective for those isolated bacteria. Oxacillin and gentamicin, frequently used in first line treatment, might encounter drug resistance in some cases. Amikacin and vancomycin, without any resistance in bacterial susceptibility tests, could be used in vision-threatening, critical, and intractable cases.

Ermap, a gene coding for a novel erythroid specific adhesion/receptor membrane protein

Ermap (erythroid membrane-associated protein), a gene coding for a novel transmembrane protein produced exclusively in erythroid cells, is described. It is mapped to murine Chromosome 4, 57 cM distal to the centromere. The initial cDNA clone was isolated from a day 9 murine embryonic erythroid cell cDNA library. The predicted peptide sequence suggests that ERMAP is a transmembrane protein with two extracellular immunoglobulin folds, as well as a highly conserved B30.2 domain and several phosphorylation consensus sequences in the cytoplasmic region. ERMAP shares a high homology throughout the entire peptide with butyrophilin, a glycoprotein essential for milk lipid droplet formation and release. A GFP-ERMAP fusion protein was localized to the plasma membrane and cytoplasmic vesicles in transiently transfected 293T cells. Northern blot analysis and in-situ hybridization demonstrated that Ermap expression was restricted to fetal and adult erythroid tissues. ERMAP is likely a novel adhesion/receptor molecule specific for erythroid cells.

Traditional Chinese medicines as immunosuppressive agents

INTRODUCTION

Traditional Chinese Medicines (TCM) have been used for centuries in China to treat various immune-mediated disorders.

METHODS

This review focuses on the clinical and experimental studies that have been performed with TCM as immunosuppressive agents for the treatment of systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), atopic eczema and solid organ transplantation.

RESULTS

The "thunder god" vine, Tripterygium wilfordii Hook F (TWHf), has been extensively used in China to treat SLE and RA. TWHf not only inhibited mitogen-stimulated lymphoproliferation, but its active derivatives have also been shown to inhibit production of proinflammatory cytokines by monocytes and lymphocytes, as well as prostaglandin E2 production via the cyclooxygenase, COX-2, pathway, a potential mechanism of action in patients with RA. Demethylzelasteral (TZ-93), a triterpenoid isolated from the root cortex of TWHf, the plant alkaloid berbamine, and the hydrophobic extract of a Chinese herbal decoction, CMX-13, were all shown to be active in prolonging allograft survival in experimental animal models of heart, skin and single lung transplants, respectively. There are few well-designed randomised placebo-controlled clinical trials demonstrating the efficacy of TCM in various diseases. Zemaphyte, a decoction of 10 herbs, has been shown to be efficacious in the treatment of atopic dermatitis in both children and adults in two randomised double-blind placebo-controlled trials.

CONCLUSION

There is both laboratory and clinical evidence that the derivatives of many of these herbs may have significant beneficial immunosuppressive effects, however, concerns of toxicity must also be addressed, as exact dosing of the active derivatives is difficult to achieve with the current prescriptions of TCM.

Induction of heat shock protein 70 protects mesangial cells against oxidative injury

The heat shock response is an immediate cellular response to elevated temperatures and other types of injury that consists of the synthesis of so-called heat shock protein (hsp). This study was designed to investigate the production and the protective role of the 70 kDa hsp (hsp70) in cultured rat mesangial cells. When mesangial cells undergo thermal (45 degrees C, 15 min) stimulation, they express hsp70 mRNA expression and increased hsp70 protein production. Following this, Northern blots show an enhanced gene expression of hsp70 at one hour that reached a maximum by 12 hours after heat shock. The hsp70 protein production, estimated by Western blots, was detectable 12 hours after heat shock and reached a maximum by 36 hours. Oxidative injury generated by xanthine and xanthine oxidase inhibited cell survival and cellular proliferation, as measured by trypan blue exclusion and [3H]-labeled thymidine uptake. It did not affect hsp70 mRNA expression. Furthermore, when mesangial cells were preconditioned by heat shock, subsequent oxidative injury caused less inhibition of cell survival and cellular proliferation. Pretreatment of cells with quercetin, a transcription inhibitor, abolished the protective effect of heat shock on subsequent oxidative injury. We conclude that heat shock, not oxidative injury, induces hsp70 in mesangial cells, and this induction of hsp70 protects mesangial cells against subsequent oxidative injury.

Role of the Janus kinase (JAK)/signal transducters and activators of transcription (STAT) cascade in advanced glycation end-product-induced cellular mitogenesis in NRK-49F cells

Advanced glycation end product (AGE) is important in the pathogenesis of diabetic nephropathy, which is characterized by cellular hypertrophy/hyperplasia leading to renal fibrosis. However, the signal transduction pathways of AGE remain poorly understood. The Janus kinase (JAK)/signal transducers and activators of transcription (STAT) pathway has been associated with cellular proliferation in some extra-renal cells. Because interstitial fibroblast proliferation might be important in renal fibrosis, we studied the role of the JAK/STAT pathway in NRK-49F (normal rat kidney fibroblast) cells cultured in AGE/BSA and non-glycated BSA. We showed that AGE dose-dependently (10-200 microgram/ml) increased cellular mitogenesis in NRK-49F cells at 5 and 7 days. However, cellular mitogenesis was unaffected by the simultaneous presence of BSA. Regarding the JAK/STAT pathway, AGE (100 microgram/ml) induced tyrosine phosphorylation of JAK2 (but not JAK1, JAK3 or TYK2) at 15-60 min; it also induced the tyrosine phosphorylation of STAT1 and STAT3 at 1-2 h and 0.5-4 h respectively. Being a transcription factor, AGE also increased the DNA-binding activities of STAT1 and STAT3 AG-490 (a specific JAK2 inhibitor) (5 microM) inhibited tyrosine phosphorylation of JAK2 and the DNA-binding activities of STAT1 and STAT3. The same results were obtained by using specific 'decoy' oligodeoxynucleotides (ODNs) that prevented STAT1 and STAT3 from binding to DNA. Meanwhile, the STAT1 or STAT3 decoy ODN and AG-490 were effective in reversing AGE-induced cellular mitogenesis. We concluded that the JAK2-STAT1/STAT3 signal transduction pathway is necessary for AGE-induced cellular mitogenesis in NRK-49F cells.

Improvement in lupus nephritis following treatment with a Chinese herbal preparation

OBJECTIVE

To study the effect of a Chinese herbal decoction (CM), which contained 21 different herbs, on clinical remission in a patient with lupus nephritis and chronic nephrotic syndrome.

DESIGN

Case report describing the clinical and laboratory markers of lupus activity in the patient before and after treatment with CM. We also studied the in vitro effect of CM and its hydrophobic extract on spontaneous IgG production by peripheral blood mononuclear cells (PBMCs) from 12 patients with systemic lupus erythematosus (SLE) compared with 9 healthy control subjects.

RESULTS

Spontaneous PBMC IgG production was significantly higher in patients with SLE (mean +/- SD, 20.4+/-10.6 x 10(-5) g/L) compared with controls (4.7+/-1.9 x 10(-5) g/L) (P<.001). Addition of CM and its hydrophobic extract to PBMCs from patients with SLE resulted in significant suppression of spontaneous IgG production.

CONCLUSIONS

The CM may contain some active pharmacological compound with immunosuppressive properties useful in the treatment of SLE. Further controlled studies are important to evaluate the efficacy of this medicine, potential toxic effects, and the possible immunosuppressive mechanisms of the active component(s).

Short- and long-term uses of calcium acetate do not change hair and serum zinc concentrations in hemodialysis patients

Calcium acetate (CaAc) acutely decreases absorption of concomitantly administered zinc gluconate (Hwang et al., AJKD 1992), but its long-term effect on zinc metabolism has not been studied. This study is intended to elucidate whether use of CaAc as phosphate binder on a daily basis affects zinc status in hemodialysis (HD) patients. Effects of CaAc on serum zinc were studied in 44 HD patients for 8 weeks (short-term). In 10 of these patients, the changes of serum and hair zinc were followed for 8 months (long-term). The daily dose of CaAc contained 25.35 mmol elemental calcium. Serum and hair zinc concentrations were measured by atomic absorptiometry. Our results were as follows: (i) in the short-term study, serum zinc concentrations did not show a significant difference compared to the baseline; (ii) in the long-term study, serum zinc concentrations showed no significant difference between different time points (11.0+/-0.5 in the beginning, 11.9+/-0.4 after 2 months, 11.4+/-0.4 after 4 months and 11.3+/-0.5 micromol/L after 8 months, n=10). However, these values were all significantly lower than in the normal controls (15.7+/-0.5 micromol/L, n=16); (iii) hair zinc content was not significantly different from the baseline level (2.7+/-0.1 in the beginning, 2.4+/-0.1 after 2 months, 2.6+/-0.2 after 4 months, 3.1+/-0.1 micromol/g hair, and from that of normal controls, 2.7+/-0.2 micromol/g hair). In conclusion, daily application of CaAc does not significantly interfere with zinc absorption and storage in HD patients. However, the comparable hair zinc content in the presence of decreased serum zinc concentrations indicates that the metabolic processing of zinc in HD patients is different from that of normal individuals.

Effects of Th2 cytokines on chemokine expression in the lung: IL-13 potently induces eotaxin expression by airway epithelial cells

Airway inflammation associated with asthma is characterized by massive infiltration of eosinophils, mediated in part by specific chemoattractant factors produced in the lung. Allergen-specific Th2 cells appear to play a central role in asthma; for example, adoptively transferred Th2 cells induced lung eosinophilia associated with induction of specific chemokines. Interestingly, Th2 supernatant alone administered intranasally to naive mice induced eotaxin, RANTES, monocyte-chemotactic protein-1, and KC expression along with lung eosinophilia. We tested the major cytokines individually and found that IL-4 and IL-5 induced higher levels of macrophage-inflammatory protein-1alpha and KC; IL-4 also increased the production of monocyte-chemotactic protein-1; IL-13 and IL-4 induced eotaxin. IL-13 was by far the most potent inducer of eotaxin; indeed, a neutralizing anti-IL-13 Ab removed most of the eotaxin-inducing activity from Th2 supernatants, although it did not entirely block the recruitment of eosinophils. While TNF-alpha did not stimulate eotaxin production by itself, it markedly augmented eotaxin induction by IL-13. IL-13 was able to induce eotaxin in the lung of JAK3-deficient mice, suggesting that JAK3 is not required for IL-13 signaling in airway epithelial cells; however, eosinophilia was not induced in this situation, suggesting that JAK3 transduces other IL-13-mediated mechanisms critical for eosinophil recruitment. Our study suggests that IL-13 is an important mediator in the pathogenesis of asthma and therefore a potential target for asthma therapy.

Mouse IL-13 enhances antibody production in vivo and acts directly on B cells in vitro to increase survival and hence antibody production

IL-13, a Th2 cytokine, exhibits similar functions to IL-4 in stimulating proliferation and class switching of human B cells. Although mouse B cells were reported to be unresponsive to IL-13, we now show that IL-13 directly stimulates mouse B cells, causing extended survival and higher Ab levels. Recombinant mouse IL-13 was administered via osmotic pump during immunization of BALB/c mice with chicken RBCs. IL-13 treatment enhanced not only the plasma levels of total IgG1, IgG2a, and IgG2b but also Ag-specific Ig levels. To examine whether IL-13 acted directly on mouse B cells, B220+ B cells were cultured with fixed, anti-CD3-activated Th2 clones. Production of IgM and IgG1 was enhanced moderately by IL-13 and strongly by IL-4. Anti-CD40-stimulated sIgD+ mouse B cells also responded to IL-13 by producing increased levels of IgM, and to a lesser extent IgG1, IgG2a, IgG2b, and IgG3. No evidence was found for IL-13-induced class switching. Mouse B cells were stimulated directly rather than indirectly via contaminating cells, as IL-13 increased the numbers of both total and Ab-secreting B cells in aliquots of 100 sIgD+ B cells (>99.5% pure) stimulated with anti-CD40 Ab. Stimulation of B cells by IL-13 was unaffected by the addition of anti-IL-4 to the cultures. In contrast to IL-4, IL-13 did not increase CD23 expression or B cell proliferation as measured by dilution of an intracellular fluorescence label. Collectively, these data indicate that IL-13 can enhance mouse B cell Ab production by increasing survival of the B cells.

A patient of primary hyperparathyroidism with full-blown bone changes simulating malignancy

The two most common causes of hypercalcemia are malignancy and primary hyperparathyroidism (1 degree HPT). The radiographic presentations and the histological findings on bone biopsy are important for differential diagnosis of underlying diseases. We report a patient with hypercalcemia who presented unusual bone manifestations. A 43 y/o woman was admitted due to right femoral fracture. X-ray on the right tibia revealed several osteolytic cystic lesions with sclerotic rims. Blood biochemistry showed anemia, impaired renal function and hypercalcemia. Multiple osteolytic lesions on the skull and bilateral forearms were also noted. Malignancy, such as multiple myeloma or metastatic cancer was suspected. However, this was excluded because of the absence of M-component on serum protein electrophoresis and the negative finding of plasma cells or other malignant cell on bone biopsy examination. Abdominal sonography demonstrated bilateral medullary nephrocalcinosis. The final diagnosis of 1 degree HPT was made, based on the findings of classic pathological pictures (brown tumor) and the markedly elevated intact parathyroid hormone (1267.4 pg/ml) level. Sonography on the neck and 201Tl/99mTc parathyroid subtraction scan localized a left lower parathyroid tumor and fine needle aspiration confirmed the parathyroid origin. Diagnosis of 1 degree HPT could only be made from recurrent urolithiasis and X-ray picture of osteitis fibrosa cystica in the past. This patient presented the full-blown skeletal changes which are uncommonly seen nowadays. The characteristic sclerotic rims suggesting increased bone formation provides a further important clue for differential diagnosis of 1 degree HPT from other malignancies with osteolytic bone lesions.

Prediction of equilibrated postdialysis BUN by an artificial neural network in high-efficiency hemodialysis

In urea kinetic modeling, postdialysis blood urea nitrogen (BUN) is usually underestimated with an overestimation of the Kt/V especially in high-efficiency hemodialysis (HD). Thus, an artificial neural network (ANN) was used to predict the equilibrated BUN (Ceq) and equilibrated Kt/V (eKt/V60) by using both predialysis, postdialysis, and low-flow postdialysis BUN. The results were compared to a Smye formula to predict Ceq and a Daugirdas' formula (eKt/V30) to predict eKt/V60. Seventy-four patients on high-efficiency or high-flux HD were recruited. Their mean urea rebound was 28.6+/-2%. Patients were divided into a "training" set (n = 40) and a validation set (n = 34) for the ANN. Their status was exchanged later, and the two results were pooled. In the prediction of Ceq, both Smye formula and low-flow ANN were equally highly accurate. In patients with a high urea rebound (>30%), although Smye formula lost its accuracy, low-flow ANN remained accurate. In the prediction of eKt/V60, both Daugirdas' formula and low-flow ANN were equally accurate, although the Smye formula was not so accurate. In patients with a high urea rebound, although both Smye and Daugirdas' formulas lost their accuracy, low-flow ANN remained accurate. We concluded that low-flow ANN can accurately predict both Ceq and eKt/V60 regardless of the degree of urea rebound.

Medullary cystic disease: a family study

Medullary cystic disease of the kidney is characterized by progressive tubulointerstitial disease with medullary cyst formation and secondary glomerular sclerosis. We treated a patient with chronic renal failure and investigated the family history of renal disease. The patient, an 18-year-old woman, was admitted due to poor appetite and fatigue for several months. Findings on physical examination were normal except for a pale conjunctiva. Urinalysis revealed only mild proteinuria with clear sediment. The hemogram showed normocytic normochromic anemia with hemoglobin 86 g/L. The patient was azotemic and her creatinine clearance rate was 10.7 mL/min. Renal sonography showed contraction of both kidneys with a marked increase in cortical echogenicity. One small cyst was found in the medullary area. Computed tomography (CT) and magnetic resonance imaging revealed several medullary cysts. Percutaneous renal biopsy showed focal and periglomerular sclerosis, marked tubular atrophy, and interstitial fibrosis. Ten of her family members were examined for renal function, and by sonography and CT. Five had medullary cysts, and three of the five showed abnormal renal function. Medullary cystic disease should be considered in the differential diagnosis of patients with renal disease and a positive family history.

Interaction between high glucose and TGF-beta in cell cycle protein regulations in MDCK cells

Transforming growth factor-beta (TGF-beta) may mediate high glucose effects in renal cells. Thus, Madin-Darby canine kidney cells were studied for the modulation of cell cycle regulatory proteins by high glucose (27.5 mM) and TGF-beta1. We showed that unlike other renal cells, TGF-beta1 mRNA and its bioactivity were not induced by high-glucose culture. Furthermore, high glucose per se increased cellular proliferation without alterations in cell size. High glucose also increased the percentage of cells in the G2/M phase while decreasing cells in the G0/G1 phase of the cell cycle. In contrast, TGF-beta1 dose dependently (1 to 4 ng/ml) decreased cellular mitogenesis while increasing hypertrophy in the cells, especially in the presence of high glucose. TGF-beta1 also increased the percentage of cells arrested in the G0/G1 phase while decreasing cells in the G2/M phase of the cell cycle. Regarding two of the cell cycle regulatory proteins, high glucose increased cdc2 kinase activity and retinoblastoma protein (pRb) phosphorylation. In contrast, TGF-beta1 decreased cdc2 kinase activity and pRb phosphorylation, especially in the presence of high glucose. Additionally, glucose dose dependently (5.5, 16.5, 27.5, and 38.5 mM) increased type I and II TGF-beta receptor protein expression. In conclusion, changes in cdc2 kinase activity and pRb phosphorylation were correlated with high glucose and TGF-beta1-induced growth effects in a cell cycle-dependent manner in the Madin-Darby canine kidney cells. Furthermore, high glucose may potentiate TGF-beta1-induced effects by enhancing TGF-beta receptor protein expression.

Recombinant human erythropoietin enhances superoxide production by FMLP-stimulated polymorphonuclear leukocytes in hemodialysis patients

Recombinant human erythropoietin (rHuEPO) is a hematopoietic growth factor that has a broad spectrum of action. We have observed the in vivo and in vitro effects of rHuEPO on the superoxide production of circulating polymorphonuclear leukocytes (PMNs) in hemodialysis patients. The PMNs were separated from heparinized blood after dextran sedimentation and Ficoll-Conray centrifugation and stimulated with formyl-methionyl-leucyl-phenylalanine (FMLP), serum-treated zymosan (STZ), or phorbol myristate acetate (PMA). The in vivo study showed that rHuEPO therapy for 12 weeks enhanced the superoxide production by FMLP-stimulated PMNs (P < 0.01). However, no significant changes on superoxide production was found in either STZ- or PMA-stimulated PMNs. Simultaneous measurement of PGE2 production by PMNs in response to all three stimulants did not show any significant changes after rHuEPO therapy. The direct in vitro effect of rHuEPO on PMNs showed that rHuEPO does not enhance the superoxide production by non-stimulated PMNs. However, preincubation of rHuEPO enhanced superoxide production from FMLP- and STZ-stimulated PMNs. Our results indicate that rHuEPO enhanced FMLP-stimulated superoxide production of PMNs both in vivo and in vitro in hemodialysis patients, which may be responsible for the increased oxidant stress in hemodialysis patients after rHuEPO therapy.

Intravenous repletion of phosphorus deficiency in the chronic renal failure patients with severe hypophosphatemia

Severe hypophosphatemia is a potentially life-threatening medical condition and might lead to a fatal outcome in critically ill patients. The situation is further complicated by the co-morbid renal failure. We evaluated the efficacy and safety of the intravenous phosphate repletion in 15 renal failure patients with severe hypophosphatemia. Six patients with advanced renal failure and nine patients under maintenance hemodialysis, 7 males and 8 females, aged between 42 and 83 years old, were found to have serum phosphate level < 1.2 mg/dL from various medical conditions and were treated with intravenous phosphate infusion. The phosphate solution prepared from sodium dihydrogen phosphate (NaH2PO4), containing 13 mg/ml phosphate and 0.5 meq/ml sodium, in the dosage 2.5-3.0 mg phosphate/Kg body weight, was administered through the central venous lins every 6-8 hours. The infusion was discontinued once serum phosphate level reached 5.0-5.5 mg/dL. Serum ionized calcium, phosphate and intact parathyroid hormone levels were serially followed at different intervals, respectively. The hemodialyzed uremic patients received their dialysis treatment as scheduled. All patients survived the hypophosphatemic period and regained normal phosphate levels after repletion. The amount of phosphate administered to reach the target level ranged between 3438 and 9150 mg and the duration of treatment varied between six and seventeen days. Hypocalcemia (< 4.2 mg/dL) was noted at eight occasions during the whole treatment period but none was symptomatic. Eleven patients recovered from the offending illness. However, four patients expired due to reasons not directly consequent to and temporally remote from hypophosphatemia. We conclude that prompt repletion of severe hypophosphatemia and phosphate deficiency with relatively slower rate of NaH2PO4 solution intravenous infusion is a safe and effective mode of treatment for renal failure and uremic patients. The longer treatment period allowed the administered minerals full equilibration. The risk of hyperkalemia is avoided and the sodium/volume load can be eliminated by dialysis.