Mannitol reduces nephron loss after warm renal ischemia in a porcine model.

BACKGROUND: Mannitol has been employed to ameliorate renal warm ischemia damage during partial nephrectomy, however, there is limited scientific evidence to support the use of mannitol during partial nephrectomy. The objective of the present study was to investigate the glomerular number after renal warm ischemia, with and without the use of mannitol in a Pig Model. METHODS: Twenty-four male pigs were assigned into three groups. Eight animals were allocated to the sham group that was subjected to laparoscopic dissection of the left renal hilum, without renal ischemia. Eight animals were allocated to the ischemia group that had the left renal hilum clamped for 30 min through laparoscopic access. Eight animals received mannitol (250 mg/kg) before the occlusion of renal hilum for 30 min. The kidneys were collected after the euthanasia of the pigs 21 days post surgery. The right kidney was utilized as a self-control for each animal. Serum creatinine, urea levels, the weight and volume of the kidneys were measured. Glomerular volumetric density, volume-weighted glomerular volume, and cortical volume were quantified through stereological methods and employed to determine the number of nephrons per kidney. Student's t test and ANOVA were used for statistical analysis. RESULTS: In the ischemia group, the left kidney recorded a reduction of 24.6% (290, 000 glomeruli) in the number of glomeruli in comparison to the right kidney. Kidneys subjected to ischemia also displayed decreased weight and volume in comparison to the sham and mannitol groups. No difference was observed between the left and right kidneys from the sham and mannitol groups. Further, no distinction in serum creatinine and urea among the groups was observed. CONCLUSION: The use of mannitol significantly reduces nephron loss during warm ischemia in pigs.

Hemodynamic effects of mannitol infusion in patients with acute intracerebral hemorrhage.

PURPOSE: To evaluate hemodynamic effects of mannitol infusion in patients with acute intracerebral hemorrhage. METHODS: Thirty patients with acute intracerebral hemorrhage were enrolled. Transcranial doppler was used to detect variables of bilateral middle cerebral arteria (MCA) including mean velocity (Vm) and pulsitility index (PI) before and after 125 ml and 250 ml mannitol infusion (0, 30, 60, 90, 120, 180, 240 min). RESULTS: When 125 ml or 250 ml mannitol was infused in patients with acute intracerebral hemorrhage, Vm of bilateral MCA elevated, and reached the top at 30 min, and then decreased. PI decreased in the affected MCA (250 ml) and in the unaffected MCA (125 ml and 250 ml). CONCLUSION: Mannitol infusion in patients with acute intracerebral hemorrhage can improve cerebral blood flow in bilateral hemispheres and decrease intracranial pressure in the hemorrhagic hemisphere (250 ml) and in the nonhemorrhagic hemisphere (125 ml and 250 ml).

Hemodynamic effects of mannitol infusion in patients with acute intracerebral hemorrhage

PURPOSE: To evaluate hemodynamic effects of mannitol infusion in patients with acute intracerebral hemorrhage. METHODS: Thirty patients with acute intracerebral hemorrhage were enrolled. Transcranial doppler was used to detect variables of bilateral middle cerebral arteria (MCA) including mean velocity (Vm) and pulsitility index (PI) before and after125ml and 250ml mannitol infusion (0, 30, 60, 90, 120, 180, 240 min). RESULTS: When 125ml or 250ml mannitol was infused in patients with acute intracerebral hemorrhage, Vm of bilateral MCA elevated, and reached the top at 30min, and then decreased. PI decreased in the affected MCA (250ml) and in the unaffected MCA (125ml and 250ml). CONCLUSION: Mannitol infusion in patients with acute intracerebral hemorrhage can improve cerebral blood flow in bilateral hemispheres and decrease intracranial pressure in the hemorrhagic hemisphere (250ml) and in the nonhemorrhagic hemisphere (125ml and 250ml).

Ontogenetic role of angiontensin-converting enzyme in rats: thirst and sodium appetite evaluation.

We investigated the influence of captopril (an angiotensin converting enzyme inhibitor) treatment during pregnancy and lactation period on hydromineral balance of the male adult offspring, particularly, concerning thirst and sodium appetite. We did not observe significant alterations in basal hydromineral (water intake, 0.3M NaCl intake, volume and sodium urinary concentration) or cardiovascular parameters in adult male rats perinatally treated with captopril compared to controls. However, male offspring rats that perinatally exposed to captopril showed a significant attenuation in water intake induced by osmotic stimulation, extracellular dehydration and beta-adrenergic stimulation. Moreover, captopril treatment during perinatal period decreased the salt appetite induced by sodium depletion. This treatment also attenuated thirst and sodium appetite aroused during inhibition of peripheral angiotensin II generation raised by low concentration of captopril in the adult offspring. Interestingly, perinatal exposure to captopril did not alter water or salt intake induced by i.c.v. administration of angiotensin I or angiotensin II. These results showed that chronic inhibition of angiotensin converting enzyme during pregnancy and lactation modifies the regulation of induced thirst and sodium appetite in adulthood.

Inhibition of water absorption in human proximal tubular epithelial cells in response to Shiga toxin-2.

Postdiarrhea hemolytic uremic syndrome (HUS) is the most common cause of acute renal failure in children in Argentina. It is well established that Shiga toxin type 2 (Stx2) causes direct damage to glomerular endothelial cells and tubular epithelial cells, leading to a reduction in the water handling capacity of the kidney. In this study, we demonstrate that Stx2 and its B subunit (Stx2B) were able to inhibit water absorption across human renal tubular epithelial cell (HRTEC) monolayers without altering the short circuit current and the (3)H-mannitol permeability. Quantitative evaluation of (14)C-inulin transport across HRTEC monolayers showed a similar transport rate both before and after HRTEC treatment with Stx2 that confirmed the integrity of the paracellular pathway. Furthermore, Stx2 produced significant protein synthesis inhibition of HRTEC at concentrations as low as 0.001 ng/ml and 1 h of incubation, whereas Stx2B did not modify it at concentrations as high as 10,000 ng/ml and 6 h of incubation. Our findings suggest that whereas the action of Stx2 appears to be caused mainly by the inhibition of protein synthesis mediated by the A subunit, the binding of Stx2B subunit to the Gb3 receptor may affect the membrane mechanisms related to water absorption. We speculate that inhibition of water absorption may occur in proximal tubular cells in vivo in response to Stx2 and may contribute to the early event of HUS pathogenesis.

Effects of vasoactive intestinal polypeptide microinjected into the nucleus tractus solitarius on jejunal electrolytes absorption in rats.

It has been shown that vasoactive intestinal polypeptide (VIP) injected into the nucleus tractus solitarius inhibits alanine absorption across the jejunum. The aim of the present study was to investigate the effects of VIP injection into the nucleus tractus solitarius on jejunal absorption of electrolytes in the rat. Fifty-three Wistar rats were submitted to midline laparotomy to expose and isolate 20 cm of jejunal loop and to perform a subdiaphragmatic troncular vagotomy. Saline or VIP (10 pg 100 nl(-1)) was injected into the rostral nucleus tractus solitarius using a stereotaxic instrument. Tyrode solution, pH 8, containing twice glucose, sodium and potassium concentration was infused (0.5 ml min(-1)) into the jejunal loop. Samples were taken at 10-min intervals during the 40-min-experiment. Injection of VIP into the nucleus tractus solitarius increased jejunal potassium absorption. Moreover, VIP associated with vagotomy resulted in inhibition of jejunal potassium absorption by VIP alone at 40 min after perfusion (5.99 +/- 0.74 vs. 9.83 +/- 0.57 microM). There was no change in jejunal sodium absorption in any of the experimental groups. VIP had a modulatory action on jejunal potassium absorption when injected into the nucleus tractus solitarius.

Comparative study of the use of diltiazem as an antispasmodic drug in coronary angiography via the transradial approach.

OBJECTIVE: To evaluate the impact of the use, prior to the procedure, of injectable diltiazem to prevent complications. METHODS: Between September 2000 and July 2001, 50 patients underwent transradial coronary angiography and were randomized to receive placebo (GI) or diltiazem (GII) through a catheter inserted into the radial artery. All patients received isosorbide mononitrate. Ultrasound analyses of the radial artery were performed before examination, 30 minutes afterwards, and 7 days afterwards to evaluate the flow, the diameter, and the artery output. RESULTS: The radial artery diameter of GI was 2.4d +/- 0.5 mm before the procedure and 2.3 +/- 0.5 mm after 30 minutes (NS), whereas in GII the diameter was 2.2 +/- 0.3 mm before the examination and +/- 2.5 0.4 mm 30 minutes after it (P<0.001). Radial artery output in group 1 was 7.3 +/- 5.l2 mL/min before the examination and 6.1 +/- 3.5 mL/min 30 minutes after the examination (NS), and GII had an increase of 5.9 +/- 2.5 mL/min before examination to 9.05 +/- 7.78 mL/min after the examination (P=0.04). Complications (spasm, occlusion, and partial obstruction) occurred in 4 patients (17.4%) in GI and did not occur in GII (P=0.04). CONCLUSION: The study suggests a decrease in vascular complications through the transradial access for coronary angiography with the use of diltiazem as an antispasmodic drug, resulting in the significant increase in the diameter of the radial artery and radial artery output.

Dual effect of local application of nitric oxide donors in a model of incision pain in rats.

The effects of local application of a cream containing nitric oxide (NO) donors, S-nitroso-N-acetylpenicillamine (SNAP) or isosorbide dinitrate were studied in a rat model of incision pain. An incision was made in the plantar aspect of a hind paw and the cream was applied inside the surgical wound. SNAP (1-10%) or isosorbide (2.5-5%) reduced the incision allodynia as measured with von Frey filaments. Higher concentrations produced a smaller or no effect, but SNAP (30%) intensified the allodynia. Allodynia was also intensified by SNAP (5% or 30%) in rats pretreated with intraplantar 1H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one (ODQ, 4 microg), a guanylate cyclase inhibitor. The effect of isosorbide (5%) was prevented by ODQ. The cream containing SNAP released 10- to 20-fold more nitrite than did isosorbide from a macrophage culture. We conclude that local application of drugs generating a low NO concentration reduces incision pain through activation of guanylate cyclase. Drugs generating high NO concentrations, however, intensify pain via a guanylate cyclase-independent mechanism.

Effects of mannitol on the acute lung injury induced by oleic acid in rats.

Our purpose was to evaluate the pulmonary effects of mannitol infusion in a rat model of acute lung injury induced by oleic acid (OA) to compare the effects of mannitol to those of another diuretic, furosemide (FUR), and to assess if mannitol effects remained after correction of the volume depletion induced by this agent. Acute lung injury was induced in Wistar rats by intravenous administration of 100 mg/kg of OA. Mannitol (1 mL of a 20% solution) was infused either 15 min before or 2 h after OA infusion. FUR was infused intravenously in a dose (1 mg/kg) that induced a similar amount of diuresis compared to mannitol. We also studied rats that received NaCl 0.9% infusion to correct for volume losses induced by mannitol. The severity of the acute lung injury was evaluated by morphometric studies of the lungs 4 h after OA infusion. The amount of intraalveolar fluid accumulation and the intensity of alveolar distention and collapse were evaluated. Mannitol infusion either 15 min before or 2 h after OA administration resulted in a significant decrease in the amount of intraalveolar edema and alveolar distention and collapse (P < 0.001). FUR administration before OA infusion had an effect similar to mannitol. We did not observe any significant effect of mannitol when the rats received saline infusion to correct for diuresis induced by mannitol. We conclude that mannitol decreases the severity of pulmonary injury induced by OA in rats. This effect is mainly due to its diuretic properties.

Retinol-induced elevation of ornithine decarboxylase activity in cultured rat Sertoli cells is attenuated by free radical scavenger and by iron chelator.

We investigated retinol effects in ornithine decarboxylase activity in Sertoli cells. We also tested the hypothesis that free radical scavengers and iron chelators may attenuate the effect of retinol. Sertoli cells isolated from 15-day-old Wistar rats were previously cultured for 48 h and then treated with retinol by 24 h with or without mannitol (1 mM) or 1,10 phenanthroline (100 microM). We measured ornithine decarboxylase and catalase activities and malondialdehyde concentrations in response to retinol treatment. In response to 7 microM retinol treatment ornithine decarboxylase activity increased 30%. Retinol-induced ornithine decarboxylase activity was significantly decreased by addition of free radical scavenger (mannitol) or iron chelator (1,10 phenanthroline). In addition the same effect was observed in catalase increased activity and in malondialdehyde concentrations. These results suggest that retinol treatment induced ornithine decarboxylase and catalase activity and increased malondialdehyde concentration. These effects appear to be mediate by ROS.

Partially folded intermediates during trypsinogen denaturation.

The equilibrium unfolding of bovine trypsinogen was studied by circular dichroism, differential spectra and size exclusion HPLC. The change in free energy of denaturation was delta GH2O = 6.99 +/- 1.40 kcal/mol for guanidine hydrochloride and delta GH2O = 6.37 +/- 0.57 kcal/mol for urea. Satisfactory fits of equilibrium unfolding transitions required a three-state model involving an intermediate in addition to the native and unfolded forms. Size exclusion HPLC allowed the detection of an intermediate population of trypsinogen whose Stokes radii varied from 24.1 +/- 0.4 A to 26.0 +/- 0.3 A for 1.5 M and 2.5 M guanidine hydrochloride, respectively. During urea denaturation, the range of Stokes radii varied from 23.9 +/- 0.3 A to 25.7 +/- 0.6 A for 4.0 M and 6.0 M urea, respectively. Maximal intrinsic fluorescence was observed at about 3.8 M urea with 8-aniline-1-naphthalene sulfonate (ANS) binding. These experimental data indicate that the unfolding of bovine trypsinogen is not a simple transition and suggest that the equilibrium intermediate population comprises one intermediate that may be characterized as a molten globule. To obtain further insight by studying intermediates representing different stages of unfolding, we hope to gain a better understanding of the complex interrelations between protein conformation and energetics.

Partially folded intermediates during trypsinogen denaturation

The equilibrium unfolding of bovine trypsinogen was studied by circular dichroism, differential spectra and size exclusion HPLC. The change in free energy of denaturation was delta GH2O = 6.99 + ou - 1.40 kcal/mol for guanidine hydrochloride and delta GH2O = 6.37 + ou - 0.57 kcal/mol for urea. Satisfactory fits of equilibrium unfolding transitions required a three-state model involving an intermediate in addition to the native and unfolded forms. Size exclusion HPLC allowed the detection of an intermediate population of trypsinogen whose Stokes radii varied from 24.1 + ou - 0.4 angstron to 26.0 + ou - 0.3 angstron 1.5 M and 2.5 M guanidine hydrochloride, respectively. During urea denaturation, the range of Stokes radii varied from 23.9 + ou - 0.3 angstron to 25.7 + ou - 0.6 angstron for 4.0 M and 6.0 M urea, respectively. Maximal intrinsic fluorescence was observed at about 3.8 M urea with 8-aniline-1-naphthalene sulfonate (ANS) binding. These experimental data indicate that the unfolding of bovine trypsinogen is not a simple transition and suggest that the equilibrium intermediate population comprises one intermediate that may be characterized as a molten globule. To obtain further insight by studying intermediates representing different stages of unfolding, we hope to gain a better understanding of the complex interrelations between protein conformation and energetics.

[Intestinal permeability in the first year of life. The effect of diarrhea]. / Permeabilidad intestinal en el primer año de vida. Efecto de la diarrea.

OBJECTIVE: The permeability of the intestinal mucosa to lactulose and mannitol was explored longitudinally in infants at 1, 3-4 and 11-12 months of age. This was also evaluated during the episodes of diarrhea that they suffered during follow-up. PATIENTS AND METHODS: Sugar excretion was measured by gas chromatography in five-hour urine samples. RESULTS: A decrease in lactulose excretion was observed, which became significant at 11-12 months of age (p = 0.02). No changes were detected in mannitol excretion, although this showed a tendency to decrease. The lactulose/mannitol (L/M) ratio remained unchanged. During the 15 episodes of diarrhea observed in these infants during the 12 month follow-up, a considerable increase in this ratio was seen, due mainly to increased lactulose excretion. CONCLUSIONS: It is hypothesized that the decrease in lactulose excretion between one and 11-12 months of age is part of the maturational process of the intestinal barrier, while diarrhea results in increased permeability due to damage to the absorptive epithelium.

Manitol- fundamentos para sua utilizaçäo / Mannitol- reasons for its utilization

O diurético osmótico manitol é uma droga amplamente utilizada em neurociruriga e neurologia a fim de diminuir a pressäo intracraniana e melhorar a microcirculaçäo cerebral. As teorias sobre seu mecanismo de açäo säo revisadas: gradiente osmótico pela barreira hematoencefálica, auto-regulaçäo vascular e neutralizaçäo dos radicais livres do oxigênio. Sua posologia é empírica, segunda a experiência própria de cada autor. O conhecimento dos critérios básicos para o uso do manitol e de sua reposiçäo hidreletrolítica é fundamental para a manutençäo da osmolaridade sérica em valores terapêuticos

Influencia de los diuréticos en el resultado de los análisis clínicos / Influence of diuretics on the result of clinical analysis

En este trabajo se realizó una revisión de los principales grupos de diuréticos, sus sitios y mecanismos de acción y sus efectos sobre las pruebas de laboratorio. Se analizó el efecto de los diuréticos sobre: el estado ácido base, los electrolitos séricos y urinarios, el ácido úrico sérico y urinario y sobre la glucemia. También se describió la influencia de los diuréticos sobre los análisis de orina. Finalmente, los efectos hematológicos de los mismos. El objetivo de este trabajo fue estudiar la influencia de los diuréticos en los análisis clínicos, buscando los mecanismos fisiopatológicos o metodológicos de los casos citados

Influencia de los diuréticos en el resultado de los análisis clínicos / Influence of diuretics on the result of clinical analysis

En este trabajo se realizó una revisión de los principales grupos de diuréticos, sus sitios y mecanismos de acción y sus efectos sobre las pruebas de laboratorio. Se analizó el efecto de los diuréticos sobre: el estado ácido base, los electrolitos séricos y urinarios, el ácido úrico sérico y urinario y sobre la glucemia. También se describió la influencia de los diuréticos sobre los análisis de orina. Finalmente, los efectos hematológicos de los mismos. El objetivo de este trabajo fue estudiar la influencia de los diuréticos en los análisis clínicos, buscando los mecanismos fisiopatológicos o metodológicos de los casos citados (AU)

[Influence of mannitol added to the nutrient solution on the mechanical performance and on the degree of myocardial edema of isolated hearts of rats]. / Influência do acréscimo de manitol à solução nutriente no desempenho mecânico e no grau de edema miocárdico de corações isolados de ratos.

PURPOSE: To analyse the influence of mannitol added to Krebs-Henseleit (KH) solution on the myocardium edema and myocardial function. METHODS: Isolated rat heart under isovolumetric contractions studied according to Langendorff's technique were perfused with KH solution at constant flow during 90 min. The coronary perfusion pressure, diastolic and systolic pressures were recorded at every 15 min. At the end of the experiment, myocardium water content was measured in hearts perfused with KH solution (group I, n = 9) and in hearts perfused with KH solution plus 8mM mannitol (group II, n = 8). These results were compared to non-perfused control heart (n = 9). RESULTS: Myocardial water content was statistically higher in group I (80.8 +/- 1.3%) compared to group II (78.1 +/- 0.7%) and control group (75.5 +/- 0.5%). Systolic arterial pressure was statistically higher in group I (86.2 +/- 11.5mmHg) compared to group II (72.7 +/- 21.1mmHg). There was no difference in the diastolic pressure between the two groups. Coronary perfusion pressure (Pp) increased progressively during the experiment in both groups. However, Pp was lower in group II than in group I. CONCLUSION: Mannitol added to KH solution significantly attenuates the myocardium edema in the isolated perfused rat heart.

Influência do acréscimo de manitol à solução nutriente no desempenho mecânico e no grau de edema miocárdico de coraçoes isolados de ratos / Influence of Mannitol Added to the Perfusion Solution on Mechanical Properties and Myocardial Edema of Isolated Rat Hearts

PURPOSE--To analyse the influence of mannitol added to Krebs-Henseleit (KH) solution on the myocardium edema and myocardial function. METHODS--Isolated rat heart under isovolumetric contractions studied according to Langendorff's technique were perfused with KH solution at constant flow during 90 min. The coronary perfusion pressure, diastolic and systolic pressures were recorded at every 15 min. At the end of the experiment, myocardium water content was measured in hearts perfused with KH solution (group I, n = 9) and in hearts perfused with KH solution plus 8mM mannitol (group II, n = 8). These results were compared to non-perfused control heart (n = 9). RESULTS--Myocardial water content was statistically higher in group I (80.8 +/- 1.3) compared to group II (78.1 +/- 0.7) and control group (75.5 +/- 0.5). Systolic arterial pressure was statistically higher in group I (86.2 +/- 11.5mmHg) compared to group II (72.7 +/- 21.1mmHg). There was no difference in the diastolic pressure between the two groups. Coronary perfusion pressure (Pp) increased progressively during the experiment in both groups. However, Pp was lower in group II than in group I. CONCLUSION--Mannitol added to KH solution significantly attenuates the myocardium edema in the isolated perfused rat heart.

Cell wall deficiency in "slime" strains of Neurospora crassa: osmotic inhibition of cell wall synthesis and beta-D-glucan synthase activity.

1. The RCP-3 S/H mutant of Neurospora crassa was obtained by vegetative selection in medium of high osmolarity of a mycelial form of an fz, sg, os-1 ("slime"-like) segregant. The mutant exhibits spheroplast-hyphal dimorphism conditioned by the osmolarity of the culture medium (Pietro et al. (1990). Journal of General Microbiology, 136: 121-129). The carbohydrate composition of the cell wall of the mutant was different from that of the wild type in the absence of an alkali-soluble galactosaminoglycan polymer. Furthermore the mutant cell wall had a somewhat lower content of beta-glucan relative to that of chitin. 2. Increasing concentrations of sorbitol in the culture medium of the mutant inhibited by 10-fold the formation of cell wall relative to total biomass. The cell wall of the mutant cultured in the presence of sorbitol lacked mannose- and galactose-containing polymers, and also showed progressively lower amounts of beta-glucan relative to chitin. 3. The activity of membrane-bound (1-3)-beta-D-glucan synthase from the mutant grown in the absence of sorbitol shared several properties with the wild type enzyme (i.e., Km app., Vmax, stability at 30 degrees C, activation by GTP gamma S, and dissociability by treatment with NaCl and Tergitol NP-40 into a membrane-bound catalytic center and a GTP-binding activating protein). On the other hand, the enzyme from the mutant but not that from the wild type was inactivated by about 15% by treatment with NaCl and detergent. 4. At high concentrations of sorbitol (1.0 M) the RCP-3 S/H mutant exclusively produced spheroplasts devoid of (1-3)-beta-D-glucan synthase activity. The defect was at the level of the membrane-bound catalytic center. The activity of the GTP-binding activating factor was apparently normal in these cells. 5. These results suggest that the definitive loss of cell wall in the N. crassa "slime" RCP-3 S/H mutant was due to a defect in (1-3)-beta-D-glucan synthase activity which was exaggerated in the presence of high osmolyte concentrations.

Avanços terapêuticos em cardiologia; Parte 2. Diureticos: estado atual em cardiologia / Therapeutic advances in cardiology; Part 2. Diuretics: up-to-date cardiology

Os diuréticos constituem-se na principal arma no tratamento da insuficiência cardíaca e da hipertensäo arterial sistêmica. Os pacientes têm uma boa e prolongada resposta com alívio da dispnéia, reduzem a pressäo venosa e a congestäo hepática. Chamamos atençäo para os efeitos adversos e o uso indevido em pacientes com edema e obesidade