Reduced Lactate Dehydrogenase Activity Research Articles

Anti-inflammatory effects of trans-anethole in a mouse model of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease that is generally characterized by progressive and irreversible airflow obstruction and alveolar destruction. Long-term treatment with current medications has been associated with various adverse effects, indicating a need for alternative approaches for the prevention and treatment of COPD. This study investigated the mechanism underlying the effects of trans-anethole in a mouse model of COPD induced by porcine pancreatic elastase (PPE) and lipopolysaccharide (LPS). BALB/c mice were orally administered trans-anethole (62.5, 125, 250, or 500mg/kg) 2h before intranasal challenge with 1.2 units of PPE and 7μg of LPS. Lactate dehydrogenase (LDH) activity, cell counts, lung histology, cytokine production, and blood pressure were analyzed. Trans-anethole reduced LDH activity and inflammatory cell counts, including macrophage, neutrophil, and lymphocyte counts. trans-anethole 125mg/kg restored the histopathological changes induced in mouse lungs by PPE and LPS. trans-anethole reduced the serum concentrations of pro-inflammatory cytokines, including interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), as well as significantly reducing blood pressure during chronic inflammation. Trans-anethole ameliorated chronic lung inflammation in a mouse model of COPD by reducing the serum concentrations of pro-inflammatory cytokines such as TNF-α and IL-6, and by reducing blood pressure. The present results indicate that trans-anethole may be a potential therapeutic agent for prophylaxis and treatment in patients with chronic lung inflammation.

Antilithiatic potential of Vernonia cinerea against calcium oxalate calculi in experimental rats

Objectives: The present manuscript was focused on evaluating the antilithiatic potential of Vernonia cinerea extract (VCE) against calcium oxalate calculi using experimental model. Methods: The drinking water containing ethylene glycol (0.75% v/v) and ammonium chloride (1% w/v) was used to induce hyperoxaluria in Wistar rats. Thirty-six rats, divided into following six groups (each containing six animals), were treated with vehicle (normal control), ethylene glycol and ammonium chloride (urolithic), Neeri (standard), 100, 300 and 500 mg/kg, VCE (tests). The experimental protocol involved the estimation of different biochemical parameters in urine, serum, kidney homogenates, and histopathological examinations of the kidney. Results: The urolithic rats showed the presence of oxalate crystals in renal tubules and significant changes in biochemical parameters like decreased creatinine clearance, increased urinary levels of oxalates, urea, calcium, phosphorus, uric acid, proteins, decreased urinary magnesium levels; increased serum levels of urea nitrogen, uric acid, calcium, phosphorus, lactate dehydrogenase; increased calcium, phosphorus, and oxalate contents in kidney homogenates. It altered the renal architecture and impaired the functions. The extract significantly (p< 0.05) reversed the biochemical changes in urine, serum and kidney homogenates in a dose-dependent manner. It improved the renal functions as indicated by improved creatinine clearance, reduced lactate dehydrogenase activity and restoration of renal architecture towards normal. Conclusions: Vernonia cinerea showed significant antilithiatic potential against oxalate calculi in glycolated rats.

Protective effects of choline against hypoxia-induced injuries of vessels and endothelial cells.

The current study aimed to lay a theoretical foundation for further development of choline as an anti-hypoxia damage drug. Wild-type, 3- to 5-month-old male Sprague-Dawley rats, weighing 180–220 g, were used in this study. The rats were randomly divided into a normoxic control group (n=16) and a chronic intermittent hypoxia (CIH) group (n=16). The effects of CIH on acetylcholine (ACh)-mediated endothelium-dependent vasodilatation in the rat cerebral basilar arterioles and mesenteric arterioles, as well as the protective effects of choline on the arterioles damaged by hypoxia were observed. Moreover, the effects of choline on endothelial cell proliferation during hypoxia were observed, and choline's functional mechanism further explored. The ACh-mediated vasodilatation of rat cerebral basilar and mesenteric arterioles significantly reduced during hypoxia (P<0.01). Choline significantly increased dilation in the rat cerebral basilar (P<0.01) and mesenteric arterioles (P<0.05) damaged by CIH compared with those in the control group. In addition, under hypoxic conditions, choline significantly promoted the proliferation of rat aortic endothelial cells (P<0.05) and significantly reduced lactate dehydrogenase activity in the cell culture supernatant in vitro (P<0.05). Furthermore, the effect of choline could be related to its ability to significantly increase the secretion of vascular endothelial growth factor (P<0.01) and activation of α7 non-neuronal nicotinic acetylcholine receptors under hypoxia (P<0.01). This study demonstrated that choline could have protective effects against hypoxic injuries.

Transcatheter paravalvular leak closure and hemolysis – a prospective registry

IntroductionParavalvular leak (PVL) related to a surgical prosthetic valve may be associated with clinically significant hemolysis. The influence of transcatheter PVL closure (TPVLC) on hemolysis remains uncertain.Material and methodsThe prospective registry included patients undergoing TPVLC due to PVL-related heart failure and/or hemolysis. Procedural data, laboratory markers of hemolysis and heart failure status were recorded at baseline, discharge and at 1- and 6-month follow-up.ResultsOf 116 patients from all those qualified for TPVLC, 79 fulfilled the inclusion/exclusion criteria. Hemolysis was significantly more frequent in patients with mitral location of PVL and with calcifications in its channel. After TPVLC prompt reduction of lactate dehydrogenase activity (617.0 (342.0–899.0) vs. 397 (310.0–480.5) IU/l, p < 0.05) and gradual resolution of anemia (hemoglobin (HGB) 11.7 (10.4–13.8) vs. 13.4 (12.9–13.8) g%, p < 0.05) over 6 months were noted. Effective closure of PVL (> 90% reduction of PVL cross-sectional area) resulted in a more prominent increase of red blood cell count and HGB than in patients with residual regurgitation. The TPVLC-related exacerbation of hemolysis was recorded in 14 patients. Its risk was aggravated by presence of significant hemolysis at baseline or residual flow either by a partially uncovered channel or across the occluder. Reduction of hemolysis after successful TPVLC was sustained in 6-month follow-up.ConclusionsRisk factors for PVL-related hemolysis were the presence of calcifications in the defect and mitral location of PVL. The TPVLC effectively reduced hemolysis if at least 90% reduction of PVL cross sectional area was achieved. The effect was sustained in 6-month follow-up. Incomplete closure of PVL may increase the magnitude of hemolysis after TPVLC, but it occurred rarely.

Exogenous Ca&lt;sup&gt;2+&lt;/sup&gt; alleviates waterlogging-caused damages to pepper

Ca2+ has been considered as a necessary ion for alleviation of stress-induced damages in plants. We investigated effects of exogenous Ca2+ on waterlogging-induced damage to pepper and its underlying mechanisms. Pepper seedlings under stress were treated by spraying of 10 mM CaCl2. Applying exogenous Ca2+ increased the biomass of pepper leaves and roots, improved photosynthetic characteristics, membrane permeability, root activity, osmotic substance contents, antioxidant enzyme and alcohol dehydrogenase activities, while it reduced lactate dehydrogenase activity. It maintained hydroxide radical contents and activities of malate dehydrogenase and succinate dehydrogenase relatively high. Our results suggested that applying exogenous Ca2+ could regulate osmotic substance contents, antioxidant system activity, root respiration, and metabolism, and subsequently alleviate waterlogging-induced damages to pepper plants.

The study of cardiomyocytes mitochondrial dysfunction in hyperhomocysteinemia and nitric oxyde deficiency

Aim. To study the influence of nitric oxide metabolism disturbance on the development of mitochondrial dysfunction in case of hyperhomocysteinemia.&#x0D; Methods. The research was conducted on 32 Wistar male rats. Hyperhomocysteinemia was simulated by intragastric injection of methionine suspension prepared using starch and Tween-80 with addition of this amino acid into the drinking water. The nitric oxide deficiency was induced by intraperitoneal injection of L-Nω-nitroarginine methyl ester (L-NAME) solution.&#x0D; Results. Hyperhomocysteinemia is accompanied by dysfunction of cardiac cells mitochondria, manifesting in growth of cytoplasmic lactate level and development of oxidative stress with increased mitochondrial proteins carbonylation. Oxidative stress is largely compensated by the activation of the antioxidant defense system (including superoxide dismutase), as evidenced by a slight decrease of succinate dehydrogenase and H+-ATPase activity, the absence of statistically significant changes of cytoplasmic lactate dehydrogenase activity. Tween-80 showed antioxidant properties, reducing the content of protein carbonyl derivatives and superoxide dismutase activity. Nitric oxide deficiency caused by the L-NAME injection was accompanied by an inhibition of aerobic oxidation processes in cardiomyocytes mitochondria, which was proved by a significant decrease in succinate dehydrogenase activity as well as slight reduction of lactate dehydrogenase activity and lactate accumulation in the cytoplasm, and an oxidative phosphorylation reduction which manifested with a decrease of H+-ATPase activity. One reason for these changes is increased carbonylation of proteins due to high production of reactive oxygen species, which is not sufficiently compensated by increased activity of superoxide dismutase.&#x0D; Conclusion. Since hyperhomocysteinemia is associated with reduced concentrations of nitric oxide metabolites in cardiomyocytes mitochondria, and changes in these organelles after the administering of methionine have some similarities with those after injection of L-NAME, it can be argued that nitric oxide deficiency plays an important role in the pathogenesis of mitochondrial dysfunction of cardiomyocytes in case of hyperhomocysteinemia.

N(1)-methylspermidine, a stable spermidine analog, prolongs anagen and regulates epithelial stem cell functions in human hair follicles.

Spermidine (Spd), the prototypic polyamine, has been shown to be essential for hair follicle (HF) growth. However, Spd can be readily converted into other polyamines, and is physiologically unstable. Therefore, to assess its individual functions on HFs, we used the metabolically stable Spd analog N(1)-methylspermidine (N(1)-MeSpd). N(1)-MeSpd was confirmed to be a metabolically stable compound, with a half life of 90 h. 0.5 µM N(1)-MeSpd strongly prolonged anagen and decreased cell apoptosis in HFs in culture after 6 days, accompanied by specific stimulation of the expression of the epithelial stem cell-associated keratin, K15. N(1)-MeSpd also reduced lactate dehydrogenase activity in the culture supernatant, a parameter of cell death and cell lysis. N(1)-MeSpd diminished intracellular reactive oxygen species production in cultured keratinocytes, and reduced tumor necrosis factor-α, interleukin (IL)-1β and IL-6 gene and protein expression after lipopolysaccharide stimulation. This suggests that some effects of N(1)-MeSpd may be mediated by anti-oxidative and anti-inflammatory effects. These additional properties of N(1)-MeSpd could be clinically important for the treatment of inflammatory alopecias and inflammatory scalp diseases.

Hydrogen sulfide reduces regional myocardial ischemia injury through protection of mitochondrial function.

Hydrogen sulfide (H2S) is a signaling gasotransmitter, involved in various physiological and pathological processes. H2S-donating drugs have been tested to conjugate the beneficial effects of H2S with other pharmaceutical properties. It has been shown that the endogenous cystathionine-γ-lyase (CSE)/H2S pathway participates in myocardial ischemia injury in isolated hearts in rats. The present study aimed to investigate the cytoprotective action of H2S against acute myocardial ischemia injury in rats. Isolated rat hearts were perfused and subjected to ischemic conditions for 4 h. The hearts were assigned to five groups: Sham, model, infarct plus low-dose (5 µmol/l) NaHS, infarct plus middle-dose (10 µmol/l) NaHS and infarct plus high-dose (20 µmol/l) NaHS. The administration of NaHS enhanced the activity of CSE, increased the content of H2S and reduced infarct volumes following myocardial ischemia injury. Furthermore, the administration of NaHS attenuated the injury to organelles (including the mitochondria, nucleus and myofilaments) by reducing lactate dehydrogenase activity, decreasing the level of mitochondrial malondialdehyde and increasing the activities of superoxide dismutase and glutathione peroxidase in the ischemic myocardial mitochondria. These protective effects of H2S against myocardial ischemia injury appeared to be mediated by its antioxidant activities and the preservation of mitochondrial function.

Optimized heterologous transfection of viable adult organotypic brain slices using an enhanced gene gun

BackgroundOrganotypic brain slices (OTBS) are an excellent experimental compromise between the facility of working with cell cultures and the biological relevance of using animal models where anatomical, morphological, and cellular function of specific brain regions can be maintained. The biological characteristics of OTBS can subsequently be examined under well-defined conditions. They do, however, have a number of limitations; most brain slices are derived from neonatal animals, as it is difficult to properly prepare and maintain adult OTBS. There are ample problems with tissue integrity as OTBS are delicate and frequently become damaged during the preparative stages. Notwithstanding these obstacles, the introduced exogenous proteins into both neuronal cells, and cells imbedded within tissues, have been consistently difficult to achieve.ResultsFollowing the ex vivo extraction of adult mouse brains, mounted inside a medium-agarose matrix, we have exploited a precise slicing procedure using a custom built vibroslicer. To transfect these slices we used an improved biolistic transfection method using a custom made low-pressure barrel and novel DNA-coated nanoparticles (40 nm), which are drastically smaller than traditional microparticles. These nanoparticles also minimize tissue damage as seen by a significant reduction in lactate dehydrogenase activity as well as propidium iodide (PI) and dUTP labelling compared to larger traditional gold particles used on these OTBS. Furthermore, following EYFP exogene delivery by gene gun, the 40 nm treated OTBS displayed a significantly larger number of viable NeuN and EYFP positive cells. These OTBS expressed the exogenous proteins for many weeks.ConclusionsOur described methodology of producing OTBS, which results in better reproducibility with less tissue damage, permits the exploitation of mature fully formed adult brains for advanced neurobiological studies. The novel 40 nm particles are ideal for the viable biolistic transfection of OTBS by reducing tissue stress while maintaining long term exogene expression.

LDH enzyme activity in human saliva: The effect of exposure to cigarette smoke and its different components

ObjectiveAldehydes and reactive nitrogen species (RNS) are important chemically active agents in cigarette smoke (CS). Salivary lactate dehydrogenase (LDH) originates predominantly from oral epithelium and was identified as an oral state marker. Its activity in saliva decreases after CS exposure. The aims of the current study were to identify the specific damaging agents in CS responsible for this activity reduction and to understand the mechanisms participating in CS oxidative damage to the salivary enzymes. MethodsPurified and salivary LDH samples were exposed to different levels of CS, pure acrolein, acetaldehyde, peroxynitrite and RNS donors. Each response of the isolated agent to the exposure was examined by a spectrophotometric enzyme activity assay and a Western blot. ResultsCS exposure caused a 34% reduction in LDH activity. Isolated treatment with unsaturated-aldehydes (acrolein, 10μmol) caused a 61% reduction, while saturated-aldehydes (acetaldehyde, 200μmol), peroxynitrite (200μM) and RNS donor (SIN-1, 2mM) caused no substantial effect. All five LDH isoenzymes reacted similarly. The carbonyl immunoblotting assay revealed a fourfold increase in carbonyl content when treated with CS and a sevenfold increase when treated with acrolein. Conclusionα,β-Unsaturated-aldehydes were identified as the main CS ingredient responsible for salivary LDH activity diminution. The effect of saturated-aldehydes and RNS donors was negligible. Unsaturated-aldehydes are capable of introducing carbonyl group into proteins, causing their dysfunction. This provides a molecular explanation for a decrease in LDH enzymatic activity in saliva.

Cytoprotective effect of bioactive sea buckthorn extract on paraquat-exposed A549 cells via induction of Nrf2 and its downstream genes

The extract of sea buckthorn (SBT) [Hippophae rhamnoides L. (Elaeagnaceae)], is used as a food supplement and traditional medicine in numerous countries. This study investigated the protective effects of the functional extract of SBT against paraquat (PQ)-induced toxicity via antioxidant mechanisms in A549 cells. The methanol extract of SBT (25-200 µg/ml) was used to protect cells against PQ (200 µM)-induced cell death. A viability assay was conducted using 3-(4,5-dimethylthioazol-2-ly)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase (LDH). Total intracellular reactive oxygen species (ROS) were measured and plotted. For validation of the SBT-induced expression of nuclear factor-E2-related factor 2 (Nrf2) and its target genes, western blot analysis and qPCR were performed. The present study showed that pretreatment of A549 cells with SBT extract significantly attenuated PQ (200 µM)-induced cellular toxicity. The maximum cytoprotective effect was identified using 200 µg/ml SBT extract; it began 24 h following exposure and was sustained up to 120 h (P<0.05). SBT extract significantly reduced LDH activity by 35.63% and ROS levels by 30.90% (P<0.05). Pretreatment with SBT extract activated Nrf2 mRNA and protein expression and its nuclear translocation. The SBT extract effectively induced Nrf2 target genes, such as NAD(P)H dehydrogenase quinone 1, glutathione peroxidase 1, glutathione reductase and catalase following treatment with PQ. Based on these results, it was hypothesized that SBT extract may be used as a potential therapeutic agent for the treatment of various oxidative stress-related diseases.

1,25-Dihydroxyvitamin D regulation of glucose metabolism in Harvey-ras transformed MCF10A human breast epithelial cells

This study was designed to investigate the impact of 1,25-dihydroxyvitamin D (1,25(OH)2D) on glucose metabolism during early cancer progression. Untransformed and ras-oncogene transfected (ras) MCF10A human breast epithelial cells were employed to model early breast cancer progression. 1,25(OH)2D modified the response of the ras cells to glucose restriction, suggesting 1,25(OH)2D may reduce the ras cell glucose addiction noted in cancer cells. To understand the 1,25(OH)2D regulation of glucose metabolism, following four-day 1,25(OH)2D treatment, metabolite fluxes at the cell membrane were measured by a nanoprobe biosensor, [13C6]glucose flux by 13C-mass isotopomer distribution analysis of media metabolites, intracellular metabolite levels by NMR, and gene expression of related enzymes was assessed. Treatment with 1,25(OH)2D reduced glycolysis as flux of glucose to 3-phosphoglycerate was reduced by 15% (P=0.017) and 32% (P<0.003) in MCF10A and ras cells respectively. In the ras cells, 1,25(OH)2D reduced lactate dehydrogenase activity by 15% (P<0.05) with a concomitant 10% reduction in the flux of glucose to lactate (P=0.006), and reduction in the level of intracellular lactate by 55% (P=0.029). Treatment with 1,25(OH)2D reduced flux of glucose to acetyl-coA 24% (P=0.002) and 41% (P<0.001), and flux to oxaloacetate 33% (P=0.003) and 34% (P=0.027) in the MCF10A and ras cells, respectively, suggesting a reduction in tricarboxylic acid (TCA) cycle activity. The results suggest a novel mechanism involving the regulation of glucose metabolism by which 1,25(OH)2D may prevent breast cancer progression.

1,25 dihydroxyvitamin D regulation of energy metabolism in MCF10 human breast epithelial cells

These studies were designed to investigate the impact of 1,25 dihydroxyvitamin D (1,25D) on the metabolic reprogramming during cancer progression towards increased glycolysis and lactate production, and reduced oxidative metabolism (Warburg effect). The ras‐oncogene transfected MCF10 human breast epithelial cells were used to study early breast cancer progression. Metabolite fluxes at the cell membrane were measured by a selective micro biosensor (mFlux), [13C6]glucose flux by 13C‐mass isotopomer distribution analysis of media metabolites (gFlux), and intracellular metabolite levels by NMR following four day 1,25D treatment. Flux of glucose to 3‐phosphoglycerate (gFlux) was reduced 32% by 1,25D, supporting a reduction in glycolysis by 1,25D. 1,25D‐induced reduction in the citric acid (TCA) cycle activity was supported by a 41% reduced flux of glucose to acetyl‐coA (gFlux), a 20% reduced oxygen uptake (mFlux) and a 29% reduced intracellular succinate (NMR). Moreover, 1,25D reduced the flux of glucose to lactate by 10% (gFlux) and reduced intracellular lactate by 55% (NMR), which is consistent with a 15% reduction in lactate dehydrogenase activity, the enzyme converting pyruvate to lactate. These studies suggest 1,25D regulates energy metabolism in early cancer progression, shifting glucose utilization towards reduced glycolysis and lactate production as well as reduced flux through the TCA cycle.Grant Funding Source : NIH R25CA128770

Activation of Pak1/Akt/eNOS signaling following sphingosine-1-phosphate release as part of a mechanism protecting cardiomyocytes against ischemic cell injury

We investigated whether plasma long-chain sphingoid base (LCSB) concentrations are altered by transient cardiac ischemia during percutaneous coronary intervention (PCI) in humans and examined the signaling through the sphingosine-1-phosphate (S1P) cascade as a mechanism underlying the S1P cardioprotective effect in cardiac myocytes. Venous samples were collected from either the coronary sinus (n = 7) or femoral vein (n = 24) of 31 patients at 1 and 5 min and 12 h, following induction of transient myocardial ischemia during elective PCI. Coronary sinus levels of LCSB were increased by 1,072% at 1 min and 941% at 5 min (n = 7), while peripheral blood levels of LCSB were increased by 579% at 1 min, 617% at 5 min, and 436% at 12 h (n = 24). In cultured cardiac myocytes, S1P, sphingosine (SPH), and FTY720, a sphingolipid drug candidate, showed protective effects against CoCl induced hypoxia/ischemic cell injury by reducing lactate dehydrogenase activity. Twenty-five nanomolars of FTY720 significantly increased phospho-Pak1 and phospho-Akt levels by 56 and 65.6% in cells treated with this drug for 15 min. Further experiments demonstrated that FTY720 triggered nitric oxide release from cardiac myocytes is through pertussis toxin-sensitive phosphatidylinositol 3-kinase/Akt/endothelial nitric oxide synthase signaling. In ex vivo hearts, ischemic preconditioning was cardioprotective in wild-type control mice (Pak1f/f), but this protection appeared to be ineffective in cardiomyocyte-specific Pak1 knockout (Pak1cko) hearts. The present study provides the first direct evidence of the behavior of plasma sphingolipids following transient cardiac ischemia with dramatic and early increases in LCSB in humans. We also demonstrated that S1P, SPH, and FTY720 have protective effects against hypoxic/ischemic cell injury, likely a Pak1/Akt1 signaling cascade and nitric oxide release. Further study on a mouse model of cardiac specific deletion of Pak1 demonstrates a crucial role of Pak1 in cardiac protection against ischemia/reperfusion injury.

Vascular Endothelial Growth Factor Attenuates Neurodegenerative Changes in the NSC-34 Motor Neuron Cell Line Induced by Cerebrospinal Fluid of Sporadic Amyotrophic Lateral Sclerosis Patients

Background: Motor neuron disease or amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the selective death of motor neurons in the spinal cord as well as motor cortex. Recently, vascular endothelial growth factor (VEGF) has been identified as a neurotrophic factor in animal models of familial ALS and other neurological diseases. Objective: The present study was designed to investigate the neuroprotective role of VEGF in the more prevalent sporadic form of ALS. Methods: We studied the effect of VEGF on the NSC-34 cell line exposed to cerebrospinal fluid (CSF) from sporadic ALS patients (ALS-CSF) in terms of lactate dehydrogenase (LDH) assay as well as choline acetyltransferase (ChAT) and phosphorylated neurofilament expression by immunocytochemistry and confocal microscopy. NSC-34 cells were exposed to CSF from patients with definite ALS and compared to controls. LDH activity was assessed in the growth media, prior to and 24 h after the addition of VEGF to the cells. At similar time points, the cells were fixed and processed for immunocytochemistry to evaluate ChAT and phosphorylated neurofilament expression. Results: Exposure to ALS-CSF caused morphological changes of NSC-34 cells like reduced differentiation and aggregation of phosphorylated neurofilaments. Enhanced LDH activity and reduced ChAT immunoreactivity were also observed. Addition of VEGF to NSC-34 cells exposed to ALS-CSF was protective in terms of reduced LDH activity and restoration of ChAT expression. Conclusion: The present study confirms that VEGF exerts a neuroprotective effect on the NSC-34 cell line by attenuating the degenerative changes induced by ALS-CSF. It thus has therapeutic potential in sporadic ALS.

Retinal metabolic state of the proline-23-histidine rat model of retinitis pigmentosa

We determined the metabolic changes that precede cell death in the dystrophic proline-23-histidine (P23H) line 3 (P23H-3) rat retina compared with the normal Sprague-Dawley (SD) rat retina. Metabolite levels and metabolic enzymes were analyzed early in development and during the early stages of degeneration in the P23H-3 retina. Control and degenerating retinas showed an age-dependent change in metabolite levels and enzymatic activity, particularly around the time when phototransduction was activated. However, lactate dehydrogenase (LDH) activity was significantly higher in P23H-3 than SD retina before the onset of photoreceptor death. The creatine/phosphocreatine system did not contribute to the increase in ATP, because phosphocreatine levels, creatine kinase, and expression of the creatine transporter remained constant. However, Na(+)-K(+)-ATPase and Mg(2+)-Ca(2+)-ATPase activities were increased in the developing P23H-3 retina. Therefore, photoreceptor apoptosis in the P23H-3 retina occurs in an environment of increased LDH, ATPase activity, and higher-than-normal ATP levels. We tested the effect of metabolic challenge to the retina by inhibiting monocarboxylate transport with alpha-cyano-4-hydroxycinnamic acid or systemically administering the phosphodiesterase inhibitor sildenafil. Secondary to monocarboxylate transport inhibition, the P23H-3 retina did not demonstrate alterations in metabolic activity. However, administration of sildenafil significantly reduced LDH activity in the P23H-3 retina and increased the number of terminal deoxynucleotidyl transferase biotin-dUPT nick end-labeled photoreceptor cells. Photoreceptor cells with a rhodopsin mutation display an increase in apoptotic markers secondary to inhibition of a phototransduction enzyme (phosphodiesterase), suggesting increased susceptibility to altered cation entry.

Effect of Palestinian Honey on Spermatogenesis in Rats

Treatment of male albino rats with 5% honey for 20 days had no significant effect on total body weight or on the relative weight of other organs like the testis, seminal vesicles, spleen, kidneys, liver, heart, or brain. The only significant change was a 17% increase in the relative weight of the epididymis (P < or = .01). The relative weight of all the other organs was similar to those in control animals treated for the same period with drinking water. Treatment of rats for the same period with the same concentration of 5% sucrose produced no significant changes in absolute or relative weight of tested organs compared to control animals. The same treatment with Palestinian honey increased significantly the epididymal sperm count by 37% (P < or = .05). The activity of testicular marker enzymes for spermatogenesis such as sorbitol dehydrogenase (SDH) was increased by 31% (P < or = .05), and lactate dehydrogenase (LDH) was reduced by 48% (P < or = .05), which indicates that treatment with honey induces spermatogenesis. Similar treatment with sucrose had no significant effect on any of the key enzymes or epididymal sperm count. In conclusion, our results show that ingestion of honey induces spermatogenesis in rats by increasing epididymal sperm count, increasing selectively the relative weight of the epididymis, and increasing SDH activity and reducing LDH activity.

Response of cytoplasmic pH to anoxia in plant tissues with altered activities of fermentation enzymes: application of methyl phosphonate as an NMR pH probe.

Acidification of the cytoplasm is a commonly observed response to oxygen deprivation in plant tissues that are intolerant of anoxia. The response was monitored in plant tissues with altered levels of lactate dehydrogenase (LDH) and pyruvate decarboxylase (PDC) with the aim of assessing the contribution of the targeted enzymes to cytoplasmic pH (pH(cyt)) regulation. The pH(cyt) was measured by in vivo (31)P nuclear magnetic resonance (NMR) spectroscopy using methyl phosphonate (MeP) as a pH probe. The potential toxicity of MeP was investigated by analysing its effect on the metabolism of radiolabelled glucose. MeP accumulated to detectable levels in the cytoplasm and vacuole of plant tissues exposed to millimolar concentrations of MeP, and the pH-dependent (31)P NMR signals provided a convenient method for measuring pH(cyt) values in tissues with poorly defined signals from the cytoplasmic inorganic phosphate pool. Pretreatment of potato (Solanum tuberosum) tuber slices with 5 mm MeP for 24 h did not affect the metabolism of [U-(14)C]glucose or the pattern of (14)CO(2) release from specifically labelled [(14)C]-substrates. Time-courses of pH(cyt) measured before, during and after an anoxic episode in potato tuber tissues with reduced activities of LDH, or in tobacco (Nicotiana tabacum) leaves with increased activities of PDC, were indistinguishable from their respective controls. MeP can be used as a low toxicity (31)P NMR probe for measuring intracellular pH values in plant tissues with altered levels of fermentation enzymes. The measurements on transgenic tobacco leaves suggest that the changes in pH(cyt) during an anoxic episode are not dominated by fermentation processes; while the pH changes in the potato tuber tissue with reduced LDH activity show that the affected isozymes do not influence the anoxic pH response.

Prunus mumeExtract Ameliorates Exercise-Induced Fatigue in Trained Rats

This study evaluated the effects of Prunus mume extract on exercise-induced fatigue recovery in a trained rat model. Male Sprague-Dawley rats were raised either on a control diet (EC) or on diets supplemented with 0.15% (0.15EP), 0.3% (0.3EP), or 0.9% (0.9EP) Prunus mume extract for 4 weeks (n = 18). Each dietary group was divided into two subgroups; at the end of the experimental period, one subgroup was sacrificed immediately after a 1-hour exercise, and the other subgroup was sacrificed after a 30-minute rest following the exercise (n = 9). Compared to the values for EC rats, serum ammonia concentration was significantly lower in 0.3EP and 0.9EP rats that were sacrificed immediately after the exercise-loading and in 0.15EP, 0.3EP and 0.9EP rats that were sacrificed after a 30-minute rest following the exercise. Compared to that in EC rats, serum lactate levels were significantly lower in rats fed 0.15% or higher levels of P. mume extract when they were sacrificed after a 30-minute rest following the exercise. Dietary supplementation with the P. mume extract significantly elevated hepatic and muscle glycogen concentrations of the rats sacrificed immediately after the exercise. P. mume extract significantly reduced lactate dehydrogenase activity and increased citrate synthase activity in the skeletal muscles of the rats sacrificed immediately after the exercise-loading. Taken together, these results indicate that the P. mume extract administered during endurance exercise training may enhance the oxidative capacity of exercising skeletal muscle and may induce the muscle to prefer fatty acids for its fuel use rather than amino acids or carbohydrates.

Molecular characterization of CcpA and involvement of this protein in transcriptional regulation of lactate dehydrogenase and pyruvate formate-lyase in the ruminal bacterium Streptococcus bovis.

A ccpA gene that encodes global catabolite control protein A (CcpA) in Streptococcus bovis was identified and characterized, and the involvement of CcpA in transcriptional control of a gene (ldh) encoding lactate dehydrogenase (LDH) and a gene (pfl) encoding pyruvate formate-lyase (PFL) was examined. The ccpA gene was shown to be transcribed as a monocistronic operon. A catabolite-responsive element (cre) was found in the promoter region of ccpA, suggesting that ccpA transcription in S. bovis is autogenously regulated. CcpA required HPr that was phosphorylated at the serine residue at position 46 (HPr-[Ser-P]) for binding to the cre site, but glucose 6-phosphate, fructose 1,6-bisphosphate, and NADP had no effect on binding. Diauxic growth was observed when S. bovis was grown in a medium containing glucose and lactose, but it disappeared when ccpA was disrupted, which indicates that CcpA is involved in catabolite repression in S. bovis. The level of ccpA mRNA was higher when cells were grown on glucose than when they were grown on lactose, which was in line with the level of ldh mRNA. When cells were grown on glucose, the ldh mRNA level was lower but the pfl mRNA level was higher in a ccpA-disrupted mutant than in the parent strain, which suggests that ldh transcription is enhanced and pfl transcription is suppressed by CcpA. The ccpA-disrupted mutant produced less lactate and more formate than the parent, probably because the mutant had reduced LDH activity and elevated PFL activity. In the upper region of both ldh and pfl, a cre-like sequence was found, suggesting that the complex consisting of CcpA and HPr-[Ser-P] binds to the possible cre sites. Thus, CcpA appears to be involved in the global regulation of sugar utilization in S. bovis.