Predestinative role acidic cerebrospinal fluid on the destiny of central channel in spinal cord following subarachnoid hemorrhage: an experimental study.

OBJECTIVE: Acidosis is the most dangerous complication in subarachnoid hemorrhage (SAH). This study aimed to investigate the effect of acidic cerebrospinal fluid on central canal structures after SAH. MATERIALS AND METHODS: Twenty-eight hybrid rabbits were studied. Blood and cerebrospinal fluid pH values were recorded before/during/after the experimental procedures. The structures related to the central canals at the level of C5 of the cervical spinal cord were then examined histopathologically. The relationship between pH values of ependymal cells and degenerated epithelial cell densities was statistically analyzed. RESULTS: Mean blood pH values and degenerated ependymal cell density (n/mm2) were as follows: 7.351 ± 0.033/23 ± 7 in control, 7.322 ± 0.059/78 ± 13 in SHAM, and 7.261 ± 0.048/254 ± 62 in study animals. Gross examinations revealed swelling, edema, pia-arachnoid adhesions, ventral canal dilatation, arachnoiditis, central canal hemorrhage, occlusions, and dilatation in the spinal cord. CONCLUSION: Cerebrospinal fluid acidosis-induced central channel pathologies should be considered an important complication of SAH following SAH.

OBJETIVO: La acidosis es la complicación más peligrosa en la hemorragia subaracnoidea (HSA). El objetivo de este estudio fue investigar el efecto del líquido cefalorraquídeo ácido en las estructuras del canal central tras la HSA. MATERIALES Y MÉTODOS: Se estudiaron 28 conejos híbridos. Se registraron los valores de pH de la sangre y del líquido cefalorraquídeo antes, durante y después de los procedimientos experimentales. A continuación se examinaron histopatológicamente las estructuras relacionadas con los canales centrales a nivel de C5 de la médula espinal cervical. Se analizó estadísticamente la relación entre los valores de pH de las células ependimarias y las densidades de células epiteliales degeneradas. RESULTADOS: Los valores medios de pH en sangre y la densidad de células ependimarias degeneradas (n/mm2) fueron los siguientes: 7.351 ± 0.033/23 ± 7 en el control, 7.322 ± 0.059/78 ± 13 en el SHAM, 7.261 ± 0.048/254 ± 62 en los animales del estudio. Los exámenes macroscópicos revelaron hinchazón, edema, adherencias pia-aracnoideas, dilatación del canal ventral, aracnoiditis, hemorragia del canal central, oclusiones y dilatación en la médula espinal. CONCLUSIONES: Las patologías del canal central inducidas por la acidosis del líquido cefalorraquídeo deben considerarse como una complicación importante de la HSA tras una hemorragia subaracnoidea.

Pro-inflammatory mediators and neutrophils are increased in synovial fluid from heifers with acute ruminal acidosis.

BACKGROUND: Acute ruminal acidosis (ARA) is a metabolic disease of cattle characterized by an aseptic synovitis. ARA is the result of an increased intake of highly fermentable carbohydrates that frequently occurs in dairy cattle subjected to high production requirements. In human joint diseases such as rheumatoid arthritis and gout, several pro-inflammatory molecules are increased in the synovial fluid, including cytokines, prostaglandin E2 (PGE2), metalloproteinases, and neutrophil extracellular traps (NETs). The aim of this study was to identify the presence of proinflammatory mediators and neutrophils in the synovial fluid of heifers with ARA, induced by an oligofructose overload. Five heifers were challenged with an oligofructose overload (13 g/kg BW) dissolved in water. As a control, a similar vehicle volume was used in four heifers. Synovial fluid samples were collected from the tarso-crural joint and PGE2, IL-6, IL-1ß, ATP, lactate dehydrogenase (LDH), albumin, glucose, matrix metalloproteinase-9 (MMP-9), cellular free DNA, NETs, and serpin B1 were analyzed at 0, 9, and 24 h post treatment. RESULTS: At 9 h post oligofructose overload, an increase of IL-1ß, IL-6, PGE2, serpin B1 and LDH was detected in the joints when compared to the control group. At 24 h, the synovial fluid was yellowish, viscous, turbid, and contained abundant neutrophils. An increase of DNA-backbone-like traps, histone 3 (H3cit), aggregated neutrophil extracellular traps (aggNETs), and serpin B1 were observed 24 h post treatment. Furthermore, albumins, LDH, ATP, MMP-9, IL-6, and IL-1ß were increased after 24 h. CONCLUSIONS: The overall results indicate that IL-1ß, IL-6 and PGE2, were the earliest proinflammatory parameters that increased in the synovial fluid of animals with ARA. Furthermore, the most sever inflammatory response in the joint was observed after 24 h and could be associated with a massive presence of neutrophils and release of aggNETs.

p38 mitogen activated protein kinase mediates cardiac Na+/H+ exchanger inhibition induced by Sildenafil.

Since the original description as potent antianginal compounds, phosphodiesterase 5A inhibitors have continuously increased their possible therapeutic applications. In the heart, Sildenafil was shown to protect against an ischemic insult by decreasing cardiac Na+/H+ exchanger (NHE1) activity, action that was mediated by protein kinase G. p38 mitogen activated protein kinase (p38MAPK) activation was described in cardiac ischemia, but its precise role remains elusive. It has been shown that p38MAPK is activated by protein kinase G (PKG) in certain non-cardiac tissues, while in others modulates NHE1 activity. Current study was aimed to seek the role of p38MAPK in the Sildenafil-triggered pathway leading to NHE1 inhibition in myocardium. Rat isolated papillary muscles were used to evaluate NHE1 activity during intracellular pH recovery from an acidic load. Protein kinases phosphorylation (activation) was determined by western blot. Sustained acidosis promoted NHE1 hyperactivity by enhancing Ser703 phosphorylation, effect that was blunted by Sildenafil. p38MAPK inhibition reversed the effect of Sildenafil on NHE1. Activation of p38MAPK, by Sodium Arsenite or Anisomycin, mimicked the inhibitory effect of Sildenafil on the exchanger. Consistently, Sildenafil induced p38MAPK phosphorylation/activation during acidosis. Neither Sildenafil nor p38MAPK inhibition affected extracellular signal-regulated kinases 1/2 phosphorylation, kinases upstream NHE1. Furthermore, inhibition of NHE1 after p38MAPK activation was precluded by preventing the activation of protein phosphatase 2A with Okadaic Acid. Taken together, these results suggest that activation of p38MAPK is a necessary step to trigger the inhibitory effect of Sildenafil on cardiac NHE1 activity, thorough a mechanism that involves protein phosphatase 2A-mediated exchanger dephosphorylation.

Placental endoplasmic reticulum stress and acidosis: relevant aspects in gestational diabetes.

In this issue, Yung and colleagues (doi: 10.1007/s00125-016-4040-2 ) report endoplasmic reticulum stress in the placenta of patients with gestational diabetes mellitus. With the use of a trophoblast-like cell line, these authors identify putative mechanisms involved in, and treatments to prevent the induction of endoplasmic reticulum stress. Here, the relevance and possible implications of these findings and areas for further research are discussed.

Metabolic acidosis aggravates experimental acute kidney injury.

AIMS: Ischemia/reperfusion (I/R) injury and metabolic acidosis (MA) are two critical conditions that may simultaneously occur in clinical practice. The result of this combination can be harmful to the kidneys, but this issue has not been thoroughly investigated. The present study evaluated the influence of low systemic pH on various parameters of kidney function in rats that were subjected to an experimental model of renal I/R injury. MAIN METHODS: Metabolic acidosis was induced in male Wistar rats by ingesting ammonium chloride (NH4Cl) in tap water, beginning 2 days before ischemic insult and maintained during the entire study. Ischemia/reperfusion was induced by clamping both renal arteries for 45 min, followed by 48 h of reperfusion. Four groups were studied: control (subjected to sham surgery, n=8), I/R (n=8), metabolic acidosis (MA; 0.28 M NH4Cl solution and sham surgery, n=6), and MA+I/R (0.28 M NH4Cl solution plus I/R, n=9). KEY FINDINGS: Compared with I/R rats, MA+I/R rats exhibited higher mortality (50 vs. 11%, p=0.03), significant reductions of blood pH, plasma bicarbonate (pBic), and standard base excess (SBE), with a severe decline in the glomerular filtration rate and tubular function. Microscopic tubular injury signals were detected. Immunofluorescence revealed that the combination of MA and I/R markedly increased nuclear factor κB (NF-κB) and heme-oxygenase 1 (HO-1), but it did not interfere with the decrease in endothelial nitric oxide synthase (eNOS) expression that was caused by I/R injury. SIGNIFICANCE: Acute ischemic kidney injury is exacerbated by acidic conditions.

Glucose-regulated protein 78 (Grp78) confers chemoresistance to tumor endothelial cells under acidic stress.

OBJECTIVES: This study was designed to investigate the activation of the unfolded protein response (UPR) in tumor associated endothelial cells (TECs) and its association with chemoresistance during acidic pH stress. MATERIALS AND METHODS: Endothelial cells from human oral squamous cell carcinomas (OSCC) were excised by laser capture microdissection (LCM) followed by analysis of UPR markers (Grp78, ATF4 and CHOP) using quantitative PCR. Grp78 expression was also determined by immunostaining. Acidic stress was induced in primary human dermal microvascular endothelial cells (HDMECs) by treatment with conditioned medium (CM) from tumor cells grown under hypoxic conditions or by adjusting medium pH to 6.4 or 7.0 using lactic acid or hydrochloric acid (HCl). HDMEC resistance to the anti-angiogenic drug Sunitinib was assessed with SRB assay. RESULTS: UPR markers, Grp78, ATF4 and CHOP were significantly upregulated in TECs from OSCC compared to HDMECs. HDMECs cultured in acidic CM (pH 6.0-6.4) showed increased expression of the UPR markers. However, severe acidosis led to marked cell death in HDMECs. Alternatively, HDMECs were able to adapt when exposed to chronic acidosis at pH 7.0 for 7 days, with concomittant increase in Grp78 expression. Chronic acidosis also confers drug resistance to HDMECs against Sunitinib. Knockdown of Grp78 using shRNA resensitizes HDMECs to drug treatment. CONCLUSIONS: UPR induction in ECs under acidic pH conditions is related to chemoresistance and may contribute to therapeutic failures in response to chemotherapy. Targeting Grp78, the key component of the UPR pathway, may provide a promising approach to overcome ECs resistance in cancer therapy.

Role of CaMKII in post acidosis arrhythmias: a simulation study using a human myocyte model.

Postacidotic arrhythmias have been associated to increased sarcoplasmic reticulum (SR) Ca(2+) load and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) activation. However, the molecular mechanisms underlying these arrhythmias are still unclear. To better understand this process, acidosis produced by CO2 increase from 5% to 30%, resulting in intracellular pH (pHi) change from 7.15 to 6.7, was incorporated into a myocyte model of excitation-contraction coupling and contractility, including acidotic inhibition of L-type Ca(2+) channel (I(CaL)), Na(+)-Ca(2+) exchanger, Ca(2+) release through the SR ryanodine receptor (RyR2) (I(rel)), Ca(2+) reuptake by the SR Ca(2+) ATPase2a (I(up)), Na(+)-K(+) pump, K(+) efflux through the inward rectifier K(+) channel and the transient outward K(+) flow (I(to)) together with increased activity of the Na(+)-H(+) exchanger (I(NHE)). Simulated CaMKII regulation affecting I(rel), I(up), I(CaL), I(NHE) and I(to) was introduced in the model to partially compensate the acidosis outcome. Late Na(+) current increase by CaMKII was also incorporated. Using this scheme and assuming that diastolic Ca(2+) leak through the RyR2 was modulated by the resting state of this channel and the difference between SR and dyadic cleft [Ca(2+)], postacidotic delayed after depolarizations (DADs) were triggered upon returning to normal pHi after 6 min acidosis. The model showed that DADs depend on SR Ca(2+) load and on increased Ca(2+) leak through RyR2. This postacidotic arrhythmogenic pattern relies mainly on CaMKII effect on I(CaL) and I(up), since its individual elimination produced the highest DAD reduction. The model further revealed that during the return to normal pHi, DADs are fully determined by SR Ca(2+) load at the end of acidosis. Thereafter, DADs are maintained by SR Ca(2+) reloading by Ca(2+) influx through the reverse NCX mode during the time period in which [Na(+)]i is elevated.

Distinct mechanisms underlie adaptation of proximal tubule Na+/H+ exchanger isoform 3 in response to chronic metabolic and respiratory acidosis.

The Na(+/)H(+) exchanger isoform 3 (NHE3) is essential for HCO(3)(-) reabsorption in renal proximal tubules. The expression and function of NHE3 must adapt to acid-base conditions. The goal of this study was to elucidate the mechanisms responsible for higher proton secretion in proximal tubules during acidosis and to evaluate whether there are differences between metabolic and respiratory acidosis with regard to NHE3 modulation and, if so, to identify the relevant parameters that may trigger these distinct adaptive responses. We achieved metabolic acidosis by lowering HCO(3)(-) concentration in the cell culture medium and respiratory acidosis by increasing CO(2) tension in the incubator chamber. We found that cell-surface NHE3 expression was increased in response to both forms of acidosis. Mild (pH 7.21 ± 0.02) and severe (6.95 ± 0.07) metabolic acidosis increased mRNA levels, at least in part due to up-regulation of transcription, whilst mild (7.11 ± 0.03) and severe (6.86 ± 0.01) respiratory acidosis did not up-regulate NHE3 expression. Analyses of the Nhe3 promoter region suggested that the regulatory elements sensitive to metabolic acidosis are located between -466 and -153 bp, where two consensus binding sites for SP1, a transcription factor up-regulated in metabolic acidosis, were localised. We conclude that metabolic acidosis induces Nhe3 promoter activation, which results in higher mRNA and total protein level. At the plasma membrane surface, NHE3 expression was increased in metabolic and respiratory acidosis alike, suggesting that low pH is responsible for NHE3 displacement to the cell surface.

Renal function in children with congenital neurogenic bladder.

AIMS: Preservation of renal function in children with congenital neurogenic bladder is an important goal of treatment for the disease. This study analyzed the evolution of renal function in patients with congenital neurogenic bladder. METHODS: We reviewed the records of 58 pediatric patients with respect to the following attributes: gender, age, etiology of neurogenic bladder, reason for referral, medical/surgical management, episodes of treated urinary tract infections, urodynamics, DMSA scintigraphy, weight, height, blood pressure, glomerular filtration rate, microalbuminuria and metabolic acidosis. Statistical analysis was performed, adopting the 5% significance level. RESULTS: The mean age at presentation was 4.2 ± 3.5 years. Myelomeningocele was the most frequent etiology (71.4%). Recurrent urinary tract infection was the reason for referral in 82.8% of the patients. Recurrent urinary tract infections were diagnosed in 84.5% of the patients initially; 83.7% of those patients experienced improvement during follow-up. The initial mean glomerular filtration rate was 146.7 ± 70.1 mL/1.73 m²/min, and the final mean was 193.6 ± 93.6 mL/1.73 m²/min, p = 0.0004. Microalbuminuria was diagnosed in 54.1% of the patients initially and in 69% in the final evaluation. Metabolic acidosis was present in 19% of the patients initially and in 32.8% in the final assessment. CONCLUSIONS: Patient referral to a pediatric nephrologist was late. A reduction in the number of urinary tract infections was observed with adequate treatment, but microalbuminuria and metabolic acidosis occurred frequently despite adequate management.

Renal function in children with congenital neurogenic bladder

AIMS: Preservation of renal function in children with congenital neurogenic bladder is an important goal of treatment for the disease. This study analyzed the evolution of renal function in patients with congenital neurogenic bladder. METHODS: We reviewed the records of 58 pediatric patients with respect to the following attributes: gender, age, etiology of neurogenic bladder, reason for referral, medical/surgical management, episodes of treated urinary tract infections, urodynamics, DMSA scintigraphy, weight, height, blood pressure, glomerular filtration rate, microalbuminuria and metabolic acidosis. Statistical analysis was performed, adopting the 5 percent significance level. RESULTS: The mean age at presentation was 4.2 ± 3.5 years. Myelomeningocele was the most frequent etiology (71.4 percent). Recurrent urinary tract infection was the reason for referral in 82.8 percent of the patients. Recurrent urinary tract infections were diagnosed in 84.5 percent of the patients initially; 83.7 percent of those patients experienced improvement during follow-up. The initial mean glomerular filtration rate was 146.7 ± 70.1 mL/1.73 m²/min, and the final mean was 193.6 ± 93.6 mL/1.73 m²/min, p = 0.0004. Microalbuminuria was diagnosed in 54.1 percent of the patients initially and in 69 percent in the final evaluation. Metabolic acidosis was present in 19 percent of the patients initially and in 32.8 percent in the final assessment. CONCLUSIONS: Patient referral to a pediatric nephrologist was late. A reduction in the number of urinary tract infections was observed with adequate treatment, but microalbuminuria and metabolic acidosis occurred frequently despite adequate management.

Study of blood porphyrin spectral profile for diagnosis of chronic renal failure.

The progression to end-stage renal failure is independent of the initial pathogenic mechanism. Metabolic acidosis is a common consequence of chronic renal failure that results from inadequate ammonium excretion and decreased tubular bicarbonate reabsorption. Protoporphyrin IX (PpIX) is the immediate metabolic precursor of the heme molecule. The purpose of this study was to evaluate the levels of erythrocytes protoporphyrin IX at an animal model during progressive renal disease. A total of 36 eight-week-old male Wistar rats were divided into six groups: Normal, 4 and 8 weeks after 5/6 nephrectomy (NX). Renal function was evaluated by creatinine clearance and plasma creatinine levels. The autofluorescence of erythrocytes porphyrin of healthy and NX rats was analyzed using fluorescence spectroscopy. Emission spectra were obtained by exciting the samples at 405 nm. Significant differences between normal and NX rats autofluorescence shape occurred in the 600-700 nm spectral region. A correlation was observed between emission band intensity at 635 nm and progression of renal disease.

Iatrogenic Wernicke's encephalopathy in allogeneic bone marrow transplantation: a study of eight cases.

Wernicke's encephalopathy (WE) is a neuropsychiatric condition generally caused by acute thiamine deficiency and classically involves the triad of altered mentation, ataxia and ophthalmoplegia. It is most common among alcoholics, but several other causes have been identified, including total parenteral nutrition (TPN) use. We present eight cases of WE in patients undergoing allogeneic BMT, where thiamine deficiency was caused by a lack of vitamin supplementation during TPN administration. Clinically, WE presented as a severe refractory metabolic acidosis, preceded by 'raspberry tongue', and ophthalmologic and neurologic dysfunction. The sites most affected were the periventricular structures and the thalamus, and no mammilary bodies lesions were found.