D-lactic acidosis (DLA) is a disease associated with D-lactatemia, acidosis and neurological signs. However, these associations are ill-defined. Bacterial fermentation in the intestine causes increasing D-lactic acid concentrations in the body. Therefore, DLA is reported secondary to gastrointestinal diseases, such as short bowel syndrome, gastroenteritis or diarrhea. Despite intestinal origin, sudden D-lactatemia is often a result of impaired D-lactate metabolism in the body.<p> Aims of this work were to determine: 1) Influence of the presence of D-lactate or acidity on neurological disturbances; 2) Effectiveness of parenteral NaHCO3 therapy in correcting cerebrospinal acidity and DLA; 3) Prevalence of DLA in diarrheic lambs and fecal D-lactate thresholds; 4) Effectiveness of malate in preventing DLA.<p> The methodological tools consisted of animal models (calves and lambs): 1) Advanced surgical procedure in calves for long-lasting atlanto-occipital catheterizations; 2) Intravenous infusions of acids to experimentally induce acidosis; 3) Intravenous NaHCO3 therapies; 4) Sampling of cerebrospinal fluid (CSF), blood, urine and feces from experimental / treated calves or diarrheic lambs for blood gas analysis, and D-lactate separation by chromatography.<p> D-lactate entered the central nervous system (> 2 mmol/L) from the circulation following experimentally induced D-lactatemia (> 5 mmol/L) and was responsible for neurological disturbances which correlated (r = 0.9, P < 0.05) with both CSF and serum D-lactate concentrations. A zenith of neurological disturbances, ataxia was evident when D-lactate concentration exceeded 12 mmol/L (CSF) and 26 mmol/L (serum), however, a nadir of acidosis (pH 6.9) caused by HCl infusions produced only mild neurological disturbances (P < 0.05). Therapeutic NaHCO3 infusions did not result paradoxical CSF acidosis, but supportive in correcting (P < 0.05) acidosis (ÄpH + 0.11) and D-lactatemia in calves.<p> In lambs, metabolic acidosis following a range of mild to severe diarrhea was observed with a corresponding range of D-lactate concentrations in both serum (< 0.05−24.0 mmol/L) and feces (< 0.05−31.0 mmol/L). D-lactate was absorbed into the circulation when the fecal D-lactate concentration exceeded 10.2 mmol/L (threshold). In calves, moderate oral use of malate produced a > 50% (P < 0.05) decrease in fecal and serum D-lactate concentrations suggesting prebiotic properties to prevent DLA. <p> This dissertation answers the critical questions about the onset of neurological signs in D-lactic acidosis, and advances the current knowledge on the metabolism of D-lactate, the prevention and treatment of acidosis.

Maternal alcohol abuse during pregnancy can result in a range of structural and functional abnormalities that include lifelong physical, mental, behavioral and learning disabilities, now collectively termed as Fetal Alcohol Spectrum Disorders (FASD). The incidence of FASD is now estimated be as high as 10 per 1000 live births. Each year, 40,000 babies are born with FASD in the United States at an estimated cost of $1.4 million per individual and total cost of $6 billion. Because of the magnitude of this problem and because the incidence has not decreased in spite intensive efforts to educate women to not abuse alcohol during pregnancy, ways to prevent or mitigate the effects of prenatal alcohol exposure must be explored in addition to education. Therefore, we wished to identify the precise mechanisms by which alcohol mediates the neurodevelopmental damage in order to develop intervention/amelioration strategies. The present study was conducted using an ovine model system. The large body mass of the ovine fetus, the longer gestation that is more similar to that of humans, and that all three trimester equivalents occur in utero, make the sheep an excellent model to study the effects of alcohol on the developing fetus. Our study establishes that maternal alcohol exposure does not result in fetal cerebral hypoxia. Instead, alcohol results in hypercapnea and acidemia leading to a cascade of events in the maternal and fetal compartments that include deficits in the levels of glutamine and glutamine-related amino acids, alterations in endocrine axes, oxidative stress, alteration in cardiovascular homeostasis and fetal neuronal loss. Further, we demonstrate that inhibiting the novel two-pore domain acid sensitive potassium channel (TASK) expressed in the cerebellar granule cells and the peripheral and central chemoreceptors may prove to a be potential therapeutic strategy. Preventive strategies that are safe to use in pregnant women and that involve glutamine-related pathways are also suggested. Finally, the study also establishes the beneficial effects of moderate alcohol consumption on the fetal skeletal system.

Dissertation (Ph.D.)--University of Toledo, 2008. / Typescript. "Submitted as partial fulfillment of the requirements for The Doctor of Philosophy degree in Exercise Science." Bibliography: leaves 5-7, 24-34, 61-66, 88-92.

Made available in DSpace on 2014-06-11T19:25:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-09-28Bitstream added on 2014-06-13T19:32:59Z : No. of bitstreams: 1 vivan_mcr_me_araca.pdf: 2758803 bytes, checksum: a64192b41cf9bd2f30e7b776b50e6f69 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A avaliação da perfusão tecidual com macroparâmetros não permite a detecção precoce de alteração na microvasculatura. A anestesia da gestante requer avaliação da perfusão e a eficácia do lactato na identificação de complicações em crianças após o parto já foi descrita. O presente estudo objetivou validar o lactato sanguíneo e correlacioná-lo a métodos, na avaliação de neonatos de parto normal ou cesariana eletiva sob anestesia geral inalatória. Foram utilizadas oito cadelas para realização de parto normal ou cesariana eletiva, com o protocolo composto de morfina, propofol e sevofluorano. Foram avaliados 24 neonatos de parto normal (GN) e 30 de cesariana (GC), com exames de sangue umbilical no nascimento para dosagem de lactato, hemogasometria, hematócrito, glicose e eletrólitos. No nascimento e aos 10 minutos de vida foram realizadas avaliações Apgar e neurológica. O lactato foi avaliado aos 10 minutos, 4 e 30 dias de vida. Os filhotes apresentaram acidose respiratória, acidemia e hipoxemia ao nascimento, mais elevada no GC. Os animais do GC apresentaram notas de Apgar e resposta neurológica menores ao nascimento, com melhora aos 10 minutos. O lactato sanguíneo foi maior nos animais do GN no nascimento, e foi maior nos animais que morreram. A correlação entre o lactato e as variáveis ocorreu em GN. O lactato sanguíneo associado aos demais parâmetros foi útil na avaliação dos neonatos do GN, porém nos animais do GC não houve correlação com a condição clínica dos animais no momento do nascimento. O procedimento anestésico influencia nos valores de lactato, e a determinação do melhor intervalo para sua avaliação nesses pacientes é necessária. / The assessment of tissue perfusion using macro parameters does not allow early detection of changes in the microvasculature. Anesthesia for pregnant patient requires evaluation of perfusion, and the lactate effectiveness in identifying complications in children after birth has been described. This study aimed to validate the blood lactate and its correlation with other methods, in the evaluation of neonates born from vaginal delivery or elective cesarean section under inhalator anesthesia. Eight dogs were used to perform normal delivery or cesarean section, with the protocol consisting of morphine, propofol and sevoflurane. At birth were evaluated 24 neonates born from vaginal delivery (NG) and 30 born from cesarean section (CG) using umbilical blood to test lactate, blood gas, hematocrit, glucose and electrolytes. Apgar score and neurologic tests were performed at birth and at 10 minutes of life. Lactate levels were evaluated at 10 minutes, 4 and 30 days of life. The puppies showed respiratory acidosis, hypoxemia and acidemia at birth, higher in the CG. The animals of CG presented lower Apgar scores and neurological response at birth, which improved in 10 minutes. Blood lactate was higher in NG animals at birth, and was higher in those who died. The correlation between lactate and the variables occurred on NG. Association of blood lactate with other parameters was useful in the evaluation of neonates on NG, but in the animals of CG there was no correlation with the clinical condition of animals at birth. Anesthesia influences the lactate values, and it is necessary to determine the best interval for evaluation in these patients.

The basis of this thesis is intended to inform the reader about the general complications of acute diabetes mellitus and its consequences. It focuses on the general definitions of the diseases, etiology, morbidity, mortality, pathogenesis of the disease, clinical presentation, treatment, and future developments in hopes of treating the disease. The major focus highlights the differences between diabetic ketoacidosis and hyperglycemic hyperosmolar state, as well as understanding the complications of diabetic hypoglycemia. The most critical effects of these disorders are also emphasized; cerebral edema, vascular thrombosis, and hyperchloremic metabolic acidosis.

The pro-inflammatory cytokine interleukin 1 (IL-1) is involved in numerous physiological and pathological processes. It contributes to thermoregulation, sleep, feeding behaviour and notably to the exacerbation of non-communicable disorders such as cancer, heart disease, stroke and epilepsy, which are the greatest cause of mortality worldwide. Given this important role, IL-1 is tightly regulated, with regulation mechanisms present at the level of its synthesis, activation and receptor engagement. However, when studying IL-1 in vitro, little notice is taken of the disease microenvironment in which it acts. Acidosis is a hallmark of disease, often due to poor perfusion resulting in a shift to anaerobic respiration, a build-up of lactic acid and poor clearance of CO2. Additionally, highly active infiltrating immune cells favour anaerobic respiration and can contribute to this local acidosis. This thesis utilised primary cell cultures, cell lines and reporter cells to explore the mechanisms of IL-1 signalling under disease-relevant acidic conditions. Subsequently, a murine seizure model was developed to further explore IL-1 signalling in disease conditions in vivo. This work demonstrated that acidic pH itself did not induce IL-1β release, however, it did promote release of minimally active 20 kDa IL-1β in response to damage associated molecular patterns (DAMPs) such as ATP, monosodium urate crystals or calcium pyrophosphate dihydrate crystals. The cleavage of pro-IL-1β into 20 kDa IL-1β was mediated by cathepsin D and was also induced on addition of lactic acid to the culture media. This 20 kDa IL-1β was not further cleaved to the active mature 17 kDa IL-1β thus its production limits the spread of inflammation. The intranasal administration of kainic acid induces seizures in C57Bl/6J mice, however, IL-1β was not observed acutely in this model thus the presence of 20 kDa IL-1β in vivo was not confirmed. In recent years, the contribution of IL-1 to disease has become well established. However, despite successes in the development of novel therapeutics targeted at blocking IL-1 activity, such as anakinra, canakinumab or rilonacept to treat cryopyrin associated periodic syndromes, a number of studies have demonstrated poor efficacy and only minor improvements in patients when targeting IL-1. Thus further knowledge of the mechanisms of IL-1 signalling in disease is required to understand this system and develop improved novel therapeutics.

Skeletal muscle fatigue is defined as a loss in the force/velocity generating capacity of a muscle. A portion of the loss in function is attributable to effects of acidosis (i.e. low pH) on the regulatory proteins, troponin and tropomyosin (Tm), which regulate the binding of myosin and actin in a calcium (Ca++) dependent manner. However, the relative role of troponin and Tm on myosin-actin function during acidosis is not clear, nor are the mechanisms underlying these effects. PURPOSE: To determine the role of Tm in the acidosis-induced depression of muscle function using isolated muscle proteins in an in vitro motility assay. METHODS: Three mutant constructs of Tm were expressed by replacing the two amino acid (histidine) residues most likely affected by low pH with alanine residues (H153A, H276A, H153A/H276A). These mutant constructs were compared to wild-type Tm (wt-Tm) in order to test whether the acidosis-induced charge change of the histidine amino acid governs the pH-dependent alteration of tropomyosin and therefore the decrease in maximal RTF velocity and Ca++-sensitivity. The effect of acidosis on regulated thin filament (RTF) function was determined by assessing the impact of low pH (pH 6.8) versus neutral pH (pH 7.4) on myosin’s ability to move RTFs in the motility assay as a function of increasing levels of Ca++. This was done separately for the wt-Tm and each structural variant. RESULTS: A two-way ANOVA (pH x Tm construct) revealed that acidosis significantly (p<0.05) depressed the maximal sliding velocity of the RTFs across all versions of Tm, but that the magnitude of the depression was similar among the wt and all of the Tm mutants. Acidosis did not significantly depress the sensitivity to Ca++ under the unloaded conditions of this assay (p>0.05). CONCLUSIONS: These data suggest that the histidine residues in tropomyosin do not mediate the acidosis-induced depression in contraction velocity observed during muscle fatigue. However, since these residues may be more important in mediating the depression of force, we are currently testing the impact of the three mutant Tm constructs on the acidosis-induced depression in Ca++-sensitivity using a loaded in vitro motility assay.

Among the basal bony fishes, the American paddlefish (Polyodon spathula) has a unique respiratory strategy of ram-ventilation. However, despite the increasing problems caused by hypoxia in natural habitats occupied by this species, little information exists about their response to hypoxia. Four studies were conducted to examine the physiological and biochemical responses of juvenile paddlefish (150-181 g) to acute and chronic hypoxia. Acute hypoxia tolerance, aerobic metabolic rates and swimming capabilities of paddlefish in an intermittent respirometer or swim flume were evaluated under normoxic (partial pressures of oxygen [pO2] =140 mm Hg) and hypoxic (pO2 =62 mm Hg) conditions at 18 °C and 26 °C. Additionally, blood oxygen transport, blood acid-base balance and metabolic stress were evaluated in paddlefish independently exposed to 4 different pO2s: normoxia =148 mm Hg, mild hypoxia =89 mm Hg, moderate hypoxia =59 mm Hg and extreme hypoxia =36 mm Hg, at 21°C. Blood samples were collected from paddlefish after they had been exposed to treatment pO2’s for 0.25, 2, 6, 24 and 72 hours, and analyzed for hematocrit, pO2, total oxygen content, pCO2, pH, hemoglobin, Na+, K+, Ca2+, Cl-, glucose, lactate, etc. A third study used 1-D and 2-D J-resolved 1H NMR to analyze metabolite changes in muscle tissue of paddlefish exposed to normoxia (148 mm Hg), or acute (0.25 h) or chronic (72 h) moderate hypoxia (59 mm Hg). The last study examined the effect of moderate hypoxia (pO2: 59 mm Hg) and subsequent recovery in normoxia (pO2: 148 mm Hg) on plasma cortisol, blood oxygen transport, blood acid-base balance, metabolic, ion-osmoregulation and enzyme parameters in paddlefish. The results indicate that paddlefish have a critical pO2 of 74 mm Hg at 18 °C and 89 mm Hg at 26 °C and a lethal oxygen threshold of ~2 mg/ L. Sensitive to moderate hypoxia, death occured after 3-8 hours of extreme hypoxia. Paddlefish have reduced capacity for metabolic depression and, as a result, survival in hypoxia is limited due to a reduction in both aerobic and anaerobic (glycogen and glucose) energy stores as well as the accumulations of toxic H+ and lactate. Nonetheless recovery is possible.

No description available.

Foram utilizados neste experimento quatro garrotes Jersey (J) e quatro Gir (G), providos de cânula ruminal. Dois meses antes da indução da acidose láctica ruminal (ALR), os animais foram alimentados com dieta padronizada a base de feno e concentrado. A ALR foi induzida experimentalmente por meio da administração de sacarose intraruminal, correspondente ao peso metabólico corrigido, segundo técnica descrita por ORTOLANI (l995). Colheitas de sangue, suco de rúmen, urina, fezes e exames clínicos foram realizados nos seguintes momentos após a indução: zero, 14, 16, 18, 20, 22 e 24 horas. O pH e as concentrações de ácido láctico total, D e L e de seus sais foram determinados em todos os materiais biológicos colhidos. No sangue foram avaliados o hematócrito, os exames gasométricos e a concentração de creatinina; esta última substância também foi determinada na urina. Após a última colheita, todo o conteúdo ruminal foi completamente retirado para a determinaçãodo seu volume. Os bovinos de ambas as raças apresentaram marcante e idêntica acidose ruminal, não ocorrendo diferença no pH e na concentração de ácido láctico total, L e D no suco de rúmen. A acidose metabólica sistêmica foi moderada em ambas as raças, porém esta foi mais intensa nos bovinos J, confirmada pelas menores concentrações médias de bicarbonato e TCO2 (P < 0,00001) e pelo menor pH sangüíneo, (p < 0,025). Os garrotes J absorveram maiores quantidades de ácido láctico total e do isômero D; este último apresentou correlação negativa com o pH sangüíneo nesta raça (r = -O,78). Os garrotes G apresentaram maior capacidade homeostática de manutenção de pH sangüíneo no final da indução, provavelmente pela maior metabolização do lactato-L. Entretanto, os mesmos animais tiveram maior grau de desidratação, evidenciado pelas maiores porcentagens de hematócrito e de déficit de volume plasmático (p < 0,00001). Nessa raça ocorreu uma menor filtração glomerular, demonstrada pela maior concentração sérica de creatinina (p < 0,00001), menor depuração deste catabólito (p < 0,003) e menor volume urinário estimado (p < 0,05). Não ocorreram diferenças significativas no pH fecal entre as raças estudadas. Houve correlação negativa entre a concentração de lactato total fecal e o correspondente pH (r = - 0,65). / Four Jersey (J) and four Gir (G) rumen-cannulated steers were used. The steers were fed, for two months before the beginning of the rumen lactic acidosis (RLA) induction, a standard diet of hay and concentrates. The RLA was induced experimentally through the administration of sucrose into the rumen, according to the corrected metabolic weight, after ORTOLANI (1995). Blood, rumen fluid, urine, and fecal samples were collected and clinical examination carried out in the following times after the induction: zero, 14, 16, 18, 20, 22 and 24 hours. The pH, the total lactic acid and its L and D isomers were determined in all samples. The hematocrit, acid-base variables and the creatinine concentration were determined in the blood samples; creatinine was also determined in the urine samples. All the rumen content was evacuated in order to evaluate its volume at the 24th h. A intense rumen acidosis was reached; no differences in the rumen fluid pH and in the concentration of the total lactic acid and its isomers were found in both studied breeds. A moderate level of systemic metabolic acidosis was reached in both breeds, but lower overall mean of bicarbonate and TCO2 (p < 0.0001) as well as blood pH (p < 0.025) were found in the J steers. These steers absorbed higher amounts of total lactic and its D isomer than the G animals; the higher the blood D-lactate concentration, the lower the blood pH (r = - O.78) in the former breed. Better blood pH homeostasis were kept, at the end of induction, by the G steers, probably by their higher efficiency to metabolize L-lactate. However, the G steers exhibited a higher level of dehydration as seen by the greater hematocrit and plasma volume deficit (p < 0.00001). They also presented a lower glomerular filtration as evidenced by the higher creatinine serum levels (p < 0.00001), its lower urinary clearance (p < 0.003) and the lower estimated urinary volume (p < 0.05). There were no differences in the fecal pH values presented by both breeds. There was a negative correlation between the fecal total lactate concentration and the fecal pH (r = - 0.65).