TGF-β1 decreases CHOP expression and prevents cardiac fibroblast apoptosis induced by endoplasmic reticulum stress

Transforming growth factor-beta 1 (TGF-β1) is a cytokine with marked pro-fibrotic action on cardiac fibroblasts (CF). TGF-β1 induces CF-to-cardiac myofibroblast (CMF) differentiation, defined by an increase in α-smooth muscle cells (α-SMA), collagen secretion and it has a cytoprotective effect against stimuli that induce apoptosis. In the Endoplasmic Reticulum (ER) lumen, misfolded protein accumulation triggers ER stress and induces apoptosis, and this process plays a critical role in cell death mediated by Ischemia/Reperfusion (I/R) injury and by ER stress inducers, such as Tunicamycin (Tn). Here, we studied the regulation of CHOP, a proapoptotic ER-stress-related transcription factor in CF under simulated I/R (sI/R) or exposed to Tn. Even though TGF-β1 has been shown to participate in ER stress, its regulatory effect on CF apoptosis and ER stress-induced by sI/R or TN has not been evaluated yet. CF from neonatal rats were exposed to sI/R, and cell death was evaluated by cell count and apoptosis by flow cytometry. ER stress was assessed by western blot against CHOP. Our results evidenced that sI/R (8/24) h or Tn triggers CF apoptosis and an increase in CHOP protein levels. TGF-β1 pre-treatment partially prevented apoptosis induced by sI/R or Tn. Furthermore, TGF-β1 pre-treatment completely prevented CHOP increase by sI/R or Tn. Additionally, we found a decrease in α-SMA expression induced by sI/R and in collagen secretion induced by Tn, which were not prevented by TGF-β1 treatment. In conclusion, TGF-β1 partially protects CF apoptosis induced by sI/R or Tn, through a mechanism that would involve ER stress.

Attenuation of endoplasmic reticulum stress using the chemical chaperone 4-phenylbutyric acid prevents cardiac fibrosis induced by isoproterenol

Increasing evidence indicates that endoplasmic reticulum (ER) stress is involved in various diseases. In the human heart, ischemia/reperfusion has been correlated to ER stress, and several markers of the unfolded protein response (UPR) participate during cardiac remodeling and fibrosis. Here, we used isoproterenol (ISO) injection as a model for in vivo cardiac fibrosis. ISO induced significant cardiomyocyte loss and collagen deposition in the damaged areas of the endocardium. These responses were accompanied by an increase in the protein levels of the luminal ER chaperones BIP and PDI, as well as an increase in the UPR effector CHOP. The use of the chemical chaperone 4-phenylbutyric acid (4-PBA) prevented the activation of the UPR, the increase in luminal chaperones and also, leads to decreased collagen deposition, cardiomyocyte loss into the damaged zones. Our results suggest that cardiac damage and fibrosis induced in vivo by the beta-adrenergic agonist ISO are tightly related to ER stress signaling pathways, and that increasing the ER luminal folding capacity with exogenously administrated 4-PBA is a powerful strategy for preventing the development of cardiac fibrosis. Additionally, 4-PBA might prevent the loss of cardiomyocytes. Our data suggests that the attenuation of ER stress pathways with pharmacological compounds such as the chemical chaperone 4-PBA can prevent the development of cardiac fibrosis and adverse remodeling.

Differential participation of angiotensin II type 1 and 2 receptors in the regulation of cardiac cell death triggered by angiotensin II

BACKGROUND

The Angiotensin II (Ang II) type 1 (AT(1)R) and type 2 (AT(2)R) receptors are increased in the heart following myocardial infarction and dilated cardiomyopathy, yet their contribution at a cellular level to compensation and/or failure remains controversial.

METHODS

We ectopically expressed AT(1)R and AT(2)R in cultured adult rat cardiomyocytes and cardiac fibroblasts to investigate Ang II-mediated cardiomyocyte hypertrophy and cardiac cell viability.

RESULTS

In adult rat cardiomyocytes, Ang II did not induce hypertrophy via the AT(1)R, and no effect of Ang II on cell viability was observed following AT(1)R or AT(2)R expression. In adult rat cardiac fibroblasts, Ang II stimulated cell death by apoptosis via the AT(1)R (but not the AT(2)R), which required the presence of extracellular calcium, and induced a rapid dissipation of mitochondrial membrane potential, which was significant from 8 h.

CONCLUSIONS

We conclude that Ang II/AT(1)R triggers apoptosis in adult rat cardiac fibroblasts, which is dependent on Ca2+ influx.

[Peritoneal dialysis solutions]

New peritoneal dialysis solutions have attracted interest in recent years, as shown by the number of publications. Overall, the most salient aspects refer to the potential clinical benefits achieved using such solutions. Reports on such benefits are sometimes conflicting. The improved preservation of kidney function seen with a biocompatible bicarbonate solution is not seen with biocompatible lactate or bicarbonate/lactate solutions. Lower CRP levels are seen with biocompatible solutions; however, other studies report similar levels. Peritoneal local inflammation parameters suggest that less inflammation occurs with new solutions as compared to the standard solutions. The decreased incidence of peritonitis achieved with a solution in the long term is not achieved with other solutions in the short term. There is no agreement as to whether UF is lower with biocompatible solutions, a well designed study did report a lower ultrafiltration (UF) with the new solutions. The higher the concentration of glucose degradation products in dialysis solutions, the higher will also be in peritoneal fluid and blood, as has brilliantly been reported. Also, the higher the concentration of glucose degradation products, the greater the generation of advanced glycosilation products. All authors conclude that further controlled studies are required to obtain more convincing evidence about the clinical benefits of the new solutions.

[Phosphorus (P) chelant in dialysis: efficacy and cost. Peritoneal dialysis solutions]

Sevelamer use has a high prevalence, and half of patients are treated with this noncalcium binder. Two randomized studies appeared in 2007 that compared the efficacy of sevelamer over calcium salts. In the more statistically potent of the two studies, no differences were found in mortality between the sevelamer and calcium groups, except for a benefit in favor of sevelamer in patients older than 65 years. In the other less statistically potent study, lower mortality was observed in the sevelamer group. Both studies have various deficiencies and a timely meta-analysis of the two studies appearing that same year concluded that there was no significant evidence demonstrating a superior efficacy of sevelamer over calcium salts. Therefore, generalized extension of its use as a first-line binder is not recommended. However, its use can be assessed in specific clinical situations. With regard to the cost-benefit ratio, as there is no evidence that greater clinical benefits are obtained with sevelamer than with calcium salts, prudence and moderation in its use are needed because of the high cost/benefit ratio demonstrated. Otherwise, we will contribute to increasing the already very high treatment cost in these patients, with one of the highest costs per life year gained in medicine. The cost/benefit ratio of sevelamer remains unattractive from an economic point of view, even if dialysis and transplant are excluded in these patients.

[Guidelines of the Spanish Society of Nephrology. Clinical practice guidelines for peritoneal dialysis]

In Spain and in each of its autonomous communities, the dialysis treatment of chronic renal disease stage 5 is totally covered by public health. Peritoneal dialysis, in any of its modalities, is established as the preferred home dialysis technique and is chosen by high percentage of patients as their choice in dialysis treatment. The Spanish Society of Nephrology has promoted a project of creation of performance guides in the field of peritoneal dialysis, entrusting a work group composed of members of the Spanish Society of Nephrology a with the development of these guides. The information offered is based on levels of evidence, opinion and clinical experience of the most relevant publications of the topic. In these guides, after defining the concept of << peritoneal dialysis>>, the obligations and responsibilities of the sanitation team of the peritoneal dialysis unit are determined, and protocols and performance procedures that try to include all the aspects that concern the patient with chronic renal disease in substitute treatment with this technique are developed. They propose prescription objectives based on available clinical evidence and, lacking this, on the consensus of the experts' opinions. The final aim is to improve the care and quality of the of the patient in peritoneal dialysis, optimizing in this way the survival of the patient and of the technique. In Spain, as in other neighbouring countries, peritoneal dialysis has an incidence and prevalence that is much lower than that of hemodialysis, ranging in the last evaluation by the Spanish Society of Nephrology between 5 and 24% in the different autonomous communities. The great majority of peritoneal dialysis units form part of the public network of the Spanish state, with special representation as a Satellite Unit or Concerted Center related to the public hospital of reference, on which it must depend.

[Role of diet in the management of osteodystrophy during progressive renal insufficiency]

Secondary hyperparathyrodism (SH) is an early manifestation of chronic renal failure (CRF), which has serious complications. Moreover, treating SH is not a risk-free process. Once in its advanced state, it is extremely difficult to reverse and therefore it is critical an early intervention and prevention. An excess of phosphorus and a deficit of calcium and calcitriol are key factors in the evolution of SH. Despite the fact that plasma phosphorus levels remain normal until an extremely advanced stage of CRF, and even apparent hyperphosphatemia in mild CRF, it has been shown that restricting dietary levels of protein and phosphorus impedes the progression of SH. A decrease of protein in the diet also decreases the amount of calcium, thus the calcium levels must be supplemented in order to prevent their deficit. In addition to that slightly diminished levels of calcitriol can be observed in the early stages of CRF, thus it is logical to provide this hormone. However, administering calcitriol may induce hypercalcemia and hyperphosphatemia, which in turn risks the onset of cardiovascular calcifications and complications. Therefore, the calcitriol dosage should be small and then adjusted according to the degree of SH. Neither the PTH levels nor alterations in the phospho-calcium metabolism follow a linear increase appropriate to the decrease in renal function, therefore we propose a treatment strategy which adapts to the different degrees of renal failure.

[Doxazosin, of modified liberation, in hemodialyzed patients]

INTRODUCTION

Valuation of doxazosin, system formulation modified, in the hypertension in the hemodialysis population.

METHOD

Arterial Hypertension (AHT) has been studied in 77 patients (p) subjected to hemodialysis (HD). Mean age (mag) was 61 years (y), range 84y-25y; 66% were males. The underlying etiology was glomerular in 19%, tubulo-interstitial in 18%, congenital in 18%, vascular in 19% and diabetic in 26%.

RESULTS

Doxazosin (system formulation modified, single daily dose (4 mg), treatment follow-up was completed in 16 patients subjected to HD for 24 weeks (wk).

CONCLUSION

It is concluded that AHT is of great importance in HD, and can be adequately controlled with the new antihypertensive drugs. In this context, doxazosin affords excellent therapeutic control, efficiency and good pharmacological tolerance.

ApoE(-/-) mice develop atherosclerosis in the absence of complement component C5

Previous studies have suggested that the terminal complex of complement may contribute to the pathogenesis of atherosclerosis. C5b-9 complexes colocalize with the extracellular lipid in the aortic intima of hypercholesterolemic rabbits, and C6-deficient rabbits develop less atherosclerosis than controls. To test the role of complement in atherosclerosis in a different animal model, C5 deficient (C5def) mice were cross-bred with atherosclerosis susceptible apoE(-/-) mice, generating mice deficient in both apoE and C5 and control apoE(-/-) mice. Progeny were typed for C5 titer and serum cholesterol levels. Both male and female mice were fed a high fat diet from weaning until 22 weeks of age. At that time there were no significant differences in plasma cholesterol or triglycerides between apoE(-/-) control and apoE(-/-)/C5def groups. Morphometric analysis of the aortic root lesions gave mean (+/-SEM) lesion areas for male apoE(-/-) and apoE(-/-)/C5def mice of 468,176 +/- 21,982 and 375,182 +/- 53,089 microm(2), respectively (n = 10 each, P value = 0.123). In female apoE(-/-) mice (n = 5), the mean lesion area was 591,981 +/- 53,242 microm(2), compared to 618,578 +/- 83,457 microm(2) for female apoE(-/-)/C5def mice (n = 10) (P value = 0.835). Thus neither male nor female mice showed a significant change in lesion area when C5 was not present. In contrast to the case in the hypercholesterolemic rabbit, activation of the terminal complex of complement does not play a major role in the development of atherosclerosis in apoE(-/-) mice.

Intestinal absorption of cholesterol is mediated by a saturable, inhibitable transporter

Although the mechanism by which dietary cholesterol is absorbed from the intestine is poorly understood, it is generally accepted that cholesterol is absorbed from bile acid micelles in the jejunum. Once inside the enterocytes, cholesterol is esterified by the action of acyl-coenzyme A:cholesterol acyltransferase (ACAT), assembled into chylomicrons, and secreted into the lymph. In this work, mechanistic aspects of cholesterol absorption were probed using compounds that block cholesterol absorption in hamsters. Sterol glycoside cholesterol absorption inhibitors, exemplified by L-166,143, (3 beta, 5 alpha,25R)-3-[(4", 6"-bis[2-fluoro-phenylcarbamoyl]-B-D-cellobiosyl)oxy]-spirostan -11-on e, potently blocked absorption of radioactive cholesterol, and the potencies of several analogs correlated with their ability to lower plasma cholesterol. Each molecule of L-166,143 blocked the uptake of 500 molecules of cholesterol, rendering it unlikely that the inhibitor interacts directly with the cholesterol or bile acid. Radiolabeled L-166,143 bound to the mucosa and binding was blocked by active, but not inactive, cholesterol absorption inhibitors. Subtle changes in the structure of sterol glycosides yielded large changes in their ability to block both cholesterol absorption and binding of radiolabeled L-166,143. Large species-to-species variation in potency was also observed. These lines of evidence support the interpretation that dietary cholesterol is absorbed via a specific transporter found in the intestinal mucosa.

A target for cholesterol absorption inhibitors in the enterocyte brush border membrane

Uptake of cholesterol by the intestinal absorptive epithelium can be selectively blocked by specific small molecules, like the sterol glycoside, L-166,143. Furthermore, (3)H-labeled L-166,143 administered orally to hamsters binds specifically to the intestinal mucosa, suggesting the existence of a cholesterol transporter. Using autoradiography, the binding site of (3)H-L-166,143 in the hamster small intestine was localized to the very apical aspect of the absorptive epithelial cells. Label was competed by non-radioactive L-166,143 and two structurally distinct cholesterol absorption inhibitors, suggesting a common site of action for these compounds. L-166,143 blocked uptake of (3)H-cholesterol into enterocytes in vivo, as demonstrated by autoradiography, suggesting that it inhibits a very early step of cholesterol absorption, incorporation into the brush border membrane. This conclusion was confirmed by studies in which intestinal brush borders were isolated from hamsters dosed with (3)H-cholesterol in the presence or absence of L-166,143. Uptake of (3)H-cholesterol into the membranes was substantially inhibited by the compound. In contrast, an inhibitor of acyl CoA:cholesterol acyltransferase, did not affect uptake of (3)H-cholesterol into the brush border membranes. These results strongly support the existence of a specific transporter that facilitates the movement of cholesterol from bile acid micelles into the brush border membranes of enterocytes.

Infectious agents are not necessary for murine atherogenesis

Recent work has revealed correlations between bacterial or viral infections and atherosclerotic disease. One particular bacterium, Chlamydia pneumoniae, has been observed at high frequency in human atherosclerotic lesions, prompting the hypothesis that infectious agents may be necessary for the initiation or progression of atherosclerosis. To determine if responses to gram-negative bacteria are necessary for atherogenesis, we first bred atherosclerosis-prone apolipoprotein (apo) E(-/)- (deficient) mice with animals incapable of responding to bacterial lipopolysaccharide. Atherogenesis was unaffected in doubly deficient animals. We further tested the role of infectious agents by creating a colony of germ-free apo E(-/)- mice. These animals are free of all microbial agents (bacterial, viral, and fungal). Atherosclerosis in germ-free animals was not measurably different from that in animals raised with ambient levels of microbial challenge. These studies show that infection is not necessary for murine atherosclerosis and that, unlike peptic ulcer, Koch's postulates cannot be fulfilled for any infectious agent in atherosclerosis.

Exit-site care with ciprofloxacin otologic solution prevents polyurethane catheter infection in peritoneal dialysis patients

OBJECTIVE

Mupirocin ointment and antiseptics are standard cleansing agents in routine exit-site care of peritoneal dialysis (PD) catheters, but these agents have a deleterious effect on polyurethane devices. We assessed the effectiveness of topical use of ciprofloxacin otologic solution for preventing exit-site infection (ESI) in PD patients with polyurethane catheters.

DESIGN

Prospective study.

SETTING

Service of Nephrology of an acute-care teaching hospital in Galdácano, Bizkaia, Spain.

PATIENTS

A total of 164 patients with polyurethane catheters inserted was studied from start of continuous ambulatory PD to the end of a 24-month period. Patients were divided into two groups according to exit-site treatment protocols.

INTERVENTION

Patients in group 1 (n = 86) were instructed on daily exit-site care with soap and water only; whereas patients in group 2 (n = 78) cleansed with soap and water, followed by application of a single-dose vial of 0.5 mL ciprofloxacin (1 mg) for application around the insertion site.

MAIN OUTCOME MEASURES

Episodes of ESI and peritonitis.

RESULTS

There were 67 episodes of ESI among patients in group 1 versus 9 episodes among patients in group 2 (p < 0.05), resulting in a rate of 0.41 and 0.06 episodes per patient-year of exposure, respectively (p < 0.001). Staphylococcus aureus ESI rate was 0.34 in group 1 versus 0.06 in group 2 (p = 0.001). Infections caused by Pseudomonas aeruginosa and other pathogens occurred in 11 patients in group 1 and in no patients in group 2 (p = 0.05). Peritonitis due to S. aureus ESI was significantly less frequent among patients treated with ciprofloxacin (1 vs 9 cases, p = 0.001). Removal of the catheter was necessary in 5 patients in group 1 and in no patients in group 2 (p < 0.05).

CONCLUSION

Daily application of ciprofloxacin otologic solution at the exit site of PD patients with polyurethane catheters inserted significantly reduces the rate of ESI caused by S. aureus and other organisms, particularly P. aeruginosa.

A fluorescent cholesterol analog traces cholesterol absorption in hamsters and is esterified in vivo and in vitro

The fluorescent cholesterol analog 22-(N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl)amino)-23,24-bisnor-5-cholen-3beta-ol (fluoresterol) was characterized as a tool for exploring the biochemistry and cell biology of intestinal cholesterol absorption. Hamsters absorbed fluoresterol in a concentration- and time-dependent manner, with an efficiency of about 15-30% that of cholesterol. Fluoresterol absorption was blocked by compounds known to inhibit cholesterol absorption, implying that fluoresterol interacts with those elements of the normal pathway for cholesterol absorption on which the inhibitors act. Confocal microscopy of small intestinal tissue demonstrated that fluoresterol was taken up by absorptive epithelial cells and packaged into lipoprotein particles, suggesting a normal route of intracellular trafficking. Uptake of fluoresterol was confirmed by biochemical analysis of intestinal tissue, and a comparison of [(3)H] cholesterol and fluoresterol content in the mucosa suggested that fluoresterol moved through the enterocytes more rapidly than did cholesterol. This interpretation was supported by measurements of fluoresterol esterification in the mucosa. Four hours after hamsters were given fluoresterol and [(3)H]cholesterol orally, 44% of the fluoresterol in the intestinal mucosa was esterified, compared to 8% of the [(3)H]cholesterol. Caco-2 cells took up 2- to 5-fold more [(3)H]cholesterol than fluoresterol from bile acid micelles, and esterified 21-24% of the fluoresterol but only 1-4% of the [(3)H]cholesterol. Thus fluoresterol apparently interacts with the proteins required for cholesterol uptake, trafficking, and processing in the small intestine.

Evaluation of the Losartan in Hemodialysis (ELHE) Study

Angiotensin converting enzyme inhibitors (ACEIs) have been shown to be effective in the treatment of dialysis patients with high blood pressure, however, they also have been associated with anaphylactoid reactions at the start of dialysis, when they have been used concomitantly with AN69 membranes. A multicenter, open six-month study was designed to test the tolerability and efficacy of losartan as antihypertensive in patients under hemodialysis (HD), with particular emphasis on the appearance of anaphylactoid reactions. HD patients with systolic blood pressure (SBP) levels > or = 140 and/or diastolic blood pressure (DBP) > or = 90 mm Hg, previously nontreated, treated but uncontrolled, or treated with a poor tolerability, were included. The study performed three controls: baseline, at month 3, and at study completion. DBP and SBP levels were measured on the six HD sessions previous to the three visits in addition to biochemical and hematology measurements. Four hundred and six patients were included. The mean age was 55 years, 42% were women, and 23.6% of the patients were dialyzed with AN69 membranes. There was a significant reduction in pre- and postdialysis SBP and DBP at three and six months. Fifteen patients discontinued the study due to adverse reactions related to losartan, and in seven of them the adverse reaction was hypotension. Only two patients have reported a possible anaphylactoid reaction on treatment with AN69, in one of them the HD session had to be stopped and losartan was discontinued. On the contrary, nine patients with a history of previous anaphylactoid reaction, with ACEIs and AN69, have not shown this complication with losartan and AN69. We conclude that losartan is a well tolerated antihypertensive by HD patients, with a very low incidence of adverse reactions, and a lower prevalence of anaphylactoid reactions than those detected with ACEIs and AN69.

Factors influencing serum aluminum in CAPD patients

The aim of this study was to find out the relationship between body iron stores and serum aluminum levels among 82 stable CAPD patients. The influence of other factors such as time on CAPD and residual renal function was also considered. Thirty-three patients received aluminum hydroxide as a phosphate binder, and they had significantly higher aluminum levels (36.45 microg/l) than the patients who were not taking aluminum preparations (17.2 microg/l, p = 0.001). A statistically-significant correlation between serum aluminum levels and residual renal function and time on CAPD was also observed (p <0.05). However, there was no relationship between serum aluminum levels and serum iron, ferritin and transferrin saturation, neither between body iron stores and total excretion of aluminum (p >0.05). In previous reports, low serum iron levels were associated with high serum aluminum concentration among hemodialysis patients. However, this effect was not observed in the CAPD population under study. The highest risk of hyperaluminemia was found in the patients who were taking aluminum hydroxide, had worse residual renal function and had been longer on CAPD.

Is there a lesser hyperparathyroidism in diabetic patients with chronic renal failure?

Diabetic patients on dialysis have lower levels of parathyroid hormone (PTH); however, there is no data regarding PTH levels with different degrees of chronic renal failure (CRF). We compared 58 diabetic patients with different degrees of CRF with 268 non-diabetic patients with CRF (serum creatinine >1.2 mg/dl). In both groups, we investigated the main biochemical parameters together with plasma calcium, phosphorus, magnesium, PTH and calcitriol. Diabetic patients showed lower levels of PTH than non-diabetics (P=0.003). The differences were observed in patients with creatinine clearance <70ml/min. We also observed differences in phosphorus, magnesium and tubular resorption of phosphate. In the group of diabetic patients, serum glucose correlated inversely with PTH. Our study suggests that poor control of diabetes (hyperglycaemia) may play a role in the pathogenesis of the hypoparathyroidism observed in patients with diabetes and CRF.

Reversibility of parathyroid gland suppression in CAPD patients with low i-PTH levels

The i-PTH response to changes in the peritoneal calcium balance was studied prospectively in a group of 13 stable CAPD patients, who presumably had adynamic bone disease, with low or normal i-PTH values and low aluminum in plasma. Five days after the reduction of dialysate calcium concentration from 1.75 mmol/l to 1 mmol/l, there was a significant elevation in the serum i-PTH. These increased PTH levels returned to baseline values when patients were changed to the 1.75 mmol/l Ca solution (p = 0.004). The changes in i-PTH mirrored the changes in peritoneal calcium balances. These results support the notion that the low or normal levels of i-PTH frequently seen in peritoneal dialysis patients are due to the hypercalcemic effects of the standard peritoneal dialysis solutions; in these patients, the parathyroid hormone production is normal since negative peritoneal balances of calcium are associated with an increase in serum i-PTH.

The importance of dietary calcium and phosphorous in the secondary hyperparathyroidism of patients with early renal failure

Secondary hyperparathyroidism (HPT) was evaluated in 157 patients with chronic renal failure (CRF). It was noted that HPT developed early in CRF at a time when plasma calcium and phosphorous were within normal limits. As creatinine clearance decreased below 80 mL/m, there was a significant decrease in plasma calcitriol and a slow and progressive significant increment in plasma parathyroid hormone (PTH). The effect of dietary intake of calcium and phosphorous was evaluated in these patients with early renal failure (ERF). They were divided into two groups. Group A was placed on a protein- and phosphorous-restricted diet (10 days) followed by a daily phosphorous-load diet (10 days). Group B had similar sequential diets plus a calcium supplement throughout the study. Dietary protein and phosphorous restriction resulted in an amelioration of the HPT only in the group of patients receiving calcium supplementation. The phosphate-load diet resulted in worsening of HPT in both groups. In summary, a deficit of calcitriol occurs early in CRF, which in turn leads to a significant increase in PTH. Phosphorous restriction, together with calcium supplementation, ameliorated the HPT of patients with ERF.

Changes in renal function in primary hypothyroidism

Renal function impairment and electrolyte disorders in hypothyroidism are frequently subtle and rarely observed in clinical practice. To assess the extent of these defects, serum concentration of electrolytes and glomerular filtration rate were estimated before and after thyroid replacement therapy in 41 patients with primary hypothyroidism. All patients had decreased glomerular filtration rates and 22 patients had increased serum creatinine levels. Although a relationship between creatinine clearance and serum thyrothropin-stimulating hormone was not found, a weak correlation between age and serum creatinine concentration was observed. Hyponatremia was documented in 45% of 22 patients with elevated serum creatinine but in only 21% of 19 patients with normal creatinine. All these defects were corrected by treatment with thyroid hormone. We conclude that creatinine clearance was slightly decreased in all patients with hypothyroidism, this decrease being more noticeable in elderly patients. The greater the impairment in renal function, the more common was the occurrence of hyponatremia.

A deficit of calcitriol synthesis may not be the initial factor in the pathogenesis of secondary hyperparathyroidism

Secondary hyperparathyroidism (HPT) develops early in chronic renal failure (CRF) at a time when plasma calcitriol levels are normal. At this time, PTH are higher than normal controls and serum phosphorous levels are lower. A decrement in total serum Ca is noted, after an oral phosphate load, only in patients with ERF. These data suggest that factors, other than a decrease in calcitriol synthesis, may be involved in the pathogenesis of HPT. A hypothesis is forwarded suggesting that an alteration in the newly cloned calcium sensor receptor may be the earliest abnormality in the HPT, preceding a decrease in plasma calcitriol levels.

[Comparative study of 2 culture methods by seeding, in hemoculture bottles, the dialysis fluid from patients in continuous ambulatory peritoneal dialysis]

BACKGROUND

Peritonitis remains a major complication of continuous ambulatory peritoneal dialysis (CAPD). The accurate diagnosis of peritonitis is a requirement for a successful CAPD program. A prospective study was performed to evaluate two culture methods.

METHODS

1. Culture of 10 ml of uncentrifuged peritoneal fluid and 2. Culture of the sediment of 50 ml centrifuged and resuspended in 20 ml of distilled water, into aerobe/anaerobe hemoculture bottles (Hemoline, BioMérieux). We processed 162 PF from 138 CAPD peritonitis episodes, 33 of whom were in antimicrobial drug therapy.

RESULTS

The sensibility/specificity of both methods (87.0/70.8 method 1 and 81.9/79.2) were similar. Both methods were more sensitive (p = 0.001) when the patient was no in antimicrobial drug therapy (60.6/88.6 method 1 and 69.7/92.4 method 2). We isolated 132 microorganisms, 64.4% Gram positive, 25.0% Gram negative, 4.6% anaerobes and 6.1% levures.

CONCLUSION

Both methods were similar and the more important factor to increase the yield of culture is to remove the antibiotic presents in centrifuged fluid.

Fluconazole treatment of candida peritonitis with delayed removal of the peritoneal dialysis catheter

Candida peritonitis was treated with fluconazole in ten continuous ambulatory peritoneal dialysis (CAPD) patients without immediate removal of the peritoneal catheter. Shortly prior to diagnosis, six patients (60%) had received broad-spectrum antibiotics. Gram stain of peritoneal fluid detected yeast in 70% of cases. In eight patients the peritoneal dialysis catheter was removed within one week of diagnosis because of clinical deterioration. In the majority of cases (90%), candida peritonitis resolved only after catheter removal in spite of ongoing fluconazole therapy. Fluconazole was well tolerated by all patients.

[Microbiological diagnosis of peritonitis in patients undergoing continuous ambulatory peritoneal dialysis. Review of 5 years at the Hospital de Galdakao]

BACKGROUND

With the aim of knowing the etiology of infectious peritonitis in patients undergoing continuous ambulatory peritoneal dialysis in our Hospital and the yield of our method of culture, we have made a revision of cases recorded during a five years period.

METHODS

The peritoneal fluids of 105 patients with peritonitis was processed as following: 10 ml of uncentrifuged liquid was placed in hemocultures bottles, aerobe and anaerobe (Hemoline, Biomérieux) and incubated for up to 15 days at 37 degrees C. An additional 50 ml of peritoneal fluid was centrifuged and the sediment used for Gram stain and placed on enriched chocolate agar. Plates were incubated for up to two days at 37 degrees C in 5% of CO2. During the last year of the review the sediment of 50 ml resuspended in sterile distilled water was placed, too, in hemoculture bottles. In 18 cases we had only the hemoculture bottles inoculated by the nurse of the Nephrology Service (those patients came at a time when the laboratory was closed). Subcultures were identified with routine methodology.

RESULTS

96 (91.43%) of the 105 dialysis effluents processed were culture positive; 91.67% were bacterial and 8.33% fungal peritonitis. 64 (69.56%) of the bacterial isolates were Gram positive and 28 (30.43%) Gram negative.

CONCLUSION

We remark the good yield of a simple culture method and the high rate of Gram negative and fungal peritonitis.

Normothermic cardioplegia: is aortic cross-clamping still synonymous with myocardial ischemia?

The enthusiastic clinical reports on normothermic blood cardioplegia contrast with the paucity of data on the myocardial metabolic effects of this technique. The present study was therefore designed to assess whether normothermic blood cardioplegia really provides an aerobic environment during aortic cross-clamping. Thirty-one patients undergoing coronary (16 patients), valve (13 patients), and transplantation (2 patients) procedures were given continuous normothermic blood cardioplegia through the coronary sinus. Myocardial metabolism was assessed either immediately before aortic unclamping (16 patients) by collecting blood simultaneously from the cardioplegia infusion line and the aortic effluent or during reperfusion (15 patients) by collecting blood simultaneously from the radial artery and the coronary sinus. All samples were assayed for markers of anaerobiosis (blood gases, lactates), leukocyte activation (elastase), and lipid peroxidation (malondialdehyde, vitamin E). At the end of arrest, oxygen extraction was low, whereas the production of lactates was small, thereby suggesting the efficacy of normothermic blood cardioplegia in maintaining a predominantly aerobic metabolism. This was confirmed by postarrest data, as oxygen extraction measured immediately after cross-clamp removal was unchanged from prearrest values, whereas lactate metabolism yielded transient and limited production followed by prompt recovery of normal extraction patterns. There was no release of elastase from the myocardium, which suggests adequate protection of the coronary endothelium from ischemic injury and the related increase in leukocyte activation. Likewise, postarrest coronary sinus concentrations of malondialdehyde and vitamin E were identical to the respective arterial concentrations, thereby ruling out the occurrence of intramyocardial lipid peroxidation at the time of reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Beta 2 microglobulin in CAPD

The peritoneal clearance (Kp) and renal clearance (Kr) of beta 2 microglobulin (beta 2 m) were studied prospectively on 50 ESRD patients treated with CAPD, in order to determine the effect of the number of daily exchanges on Kp and to investigate the factors which influence the serum levels of beta 2m. Kr and Kp of beta 2m and creatinine (Cr) were calculated using standard formulae at the initiation of study and again at 6, 12, 18 and 24 months by collecting 24 hour urinary output and dialysate effluent. Kp of beta 2m of patients on 3 exchanges/day was .94 +/- .08 ml/min at the initiation of study and 1.1 +/- .08 at the end. For patients on 4 exchanges/day it was .99 +/- .14 ml/min and 1.1 +/- .12 respectively. There was no significant difference. Serum levels of beta 2m were lower on patients with significant residual renal function (RRF) (17 +/- .9 mg/L) than on patients without RRF (38 +/- 2 mg/L. p = .001). Serum levels of beta 2m correlated inversely with Kr of Cr and beta 2m at the initiation of study and at the end (r = .67 and .77 respectively, p = .0001). We conclude that serum levels of beta 2m correlate inversely with Kr of Cr and are expected to rise as RRF decreases. The combined peritoneal and renal excretion of beta 2m is less than its daily production. The number of dialysis exchanges does not influence Kp of beta 2m.

A volume-dependent, chloride-sensitive component of taurine release stimulated by potassium from retina

Chick retinas exposed to 56 mM KCl showed marked swelling of cells and synaptic structures, detected by morphological examination as well as by measurements of cell water content. Retinal cell swelling is prevented by omission of chloride. Potassium chloride, 56 mM, elicited the efflux of [3H]taurine by a process that is partly calcium-dependent, highly chloride-dependent (80%), and sensitive to furosemide. The release of [3H]dopamine under the same conditions is completely calcium-dependent and increases in the absence of chloride. The chloride-dependent component of [3H]taurine efflux seems related to increases in volume changes since it is markedly reduced when cell swelling is prevented either by maintaining constant the K X Cl product (Donnan equilibrium) or by making the solution hypertonic with mannitol. Omission of calcium and of chloride showed additive effects, practically suppressing the potassium-stimulated release of taurine. These results suggest that the potassium-stimulated efflux of [3H]taurine consists of a large component associated to changes in cell volume and a small component probably related to the depolarizing effects of potassium.

A chloride-dependent component of the release of labeled GABA and taurine from the chick retina

The characteristics and ionic dependence of the release of [3H]gamma-aminobutyric acid ([3H]GABA) and [3H]taurine from the chick retina, stimulated by kainic acid (KA) and by depolarizing concentrations of potassium was examined and compared to those of [3H]dopamine. KA (100 microM) highly stimulated the release of [3H]GABA (25-fold over resting efflux), induced a moderate increase in [3H]taurine and did not increase the efflux of [3H]dopamine. The efflux of [3H]GABA stimulated by KA was totally calcium-independent but it was markedly sodium and chloride dependent. Chloride dependence was assessed by replacing chloride with the impermeant anion gluconate, or by addition of the anion transport blocker 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). Depolarizing concentrations of KCl (56 mM) stimulated the release of [3H]GABA, [3H]taurine and [3H]dopamine to about the same extent. The release of [3H]GABA and [3H]taurine was only partially calcium dependent, in contrast to the highly calcium-dependent efflux of [3H]dopamine. A sodium-free medium increased the resting efflux and decreased the potassium-stimulated release of [3H]GABA and [3H]taurine; the resting efflux of [3H]dopamine was unaffected and the potassium-induced efflux was somewhat increased. The potassium-stimulated efflux of [3H]GABA and [3H]taurine showed a chloride-dependent component which was higher for taurine whereas the resting efflux was not modified. The stimulated release of [3H]dopamine was increased in a chloride-free medium. The ionic dependence of KA and potassium stimulated efflux of [3H]GABA and [3H]taurine showed properties similar to those of the homoexchange-activated efflux of amino acids which was also found sodium and chloride dependent and clearly different from the calcium-coupled neurotransmitter release process. Exposure of retinas to KA and potassium produced retinal cell swelling which is prevented in a chloride-free medium. Results are discussed in terms of a particular efflux mechanism for [3H]GABA and [3H]taurine in the retina in response to stimulation associated with changes in ionic gradients and retinal cell swelling.

Clinical and histological kidney involvement in human kala-azar

A 19-year-old women developed prolonged fever, weight loss, hepatosplenomegaly, anemia, leukopenia, and hyperglobulinemia. Appropriate tests indicated that she had visceral leishmaniasis (kala-azar). Urinalysis demonstrated significant proteinuria and microhematuria with the presence of red cell casts. A kidney biopsy was performed. Light microscopy showed a slight mesangial thickening and segmental mesangial proliferation. Immunofluorescence demonstrated deposits of immunoglobulins A and M, complement, and fibrinogen. Electron microscopy showed subendothelial and intramembranous deposits. After treatment with N-methylglucamine antimonate the proteinuria and microhematuria disappeared and the patient recovered uneventfully.