Lactatc Dehydrogenase Isoenzymes in Normal BovineSerum and during Experimental Liver and Muscle Damage

Influence of meat batter addition in ground beef on structural properties and quality parameters

The determination of the amount of non-intact cells (ANIC) in ground beef products is usually performed using a time-consuming and subjective histometric approach neglecting structural properties, which is why more objective and faster methods including evaluation of quality parameters are needed. To determine, whether the addition of meat batter increases the histologically determined ANIC ground beef samples containing increasing shares of meat batter (non-intact cells) were investigated histologically and results were compared to other methodological approaches, namely lactate dehydrogenase activity (LDH), soluble protein content, metmyoglobin content, drip loss, firmness, and cooking loss. Histological measurements showed that ANIC increased linearly with the addition of meat batter to ground beef. The quality parameters drip loss (r = − 0.834, p < 0.01) and firmness (r = − 0.499, p < 0.01), and the structural parameter metmyoglobin content (r = 0.924, p < 0.01) revealed significant correlations with the amount of added meat batter, and detected differences between ground beef samples when the difference in the amount of added batter-like-substance was ≥ 25%. Therefore, those methods might be useful to estimate and extrapolate ANIC, and assess product quality of ground beef samples in a faster and simpler way. The cooking loss was not affected by meat batter addition, whereas LDH activity revealed non-repeatable results. Taken together, histometric methods are useful to measure ANIC, nevertheless, it is limited in terms of characterization of morphological and structural changes in the meat. However, other parameters were correlated and could, in addition, be used for assessing the quality of ground meat.

Clinical and Diagnostic Significance of Lactate Dehydrogenase and Its Isoenzymes in Animals

Lactate dehydrogenase (LDH) is widely distributed enzyme in cells of various living systems where it is involved in carbohydrate metabolism catalyzing interconversion of lactate and pyruvate with NAD⁺/NADH coenzyme system. Cells of tissues are direct source of lactate dehydrogenase isoenzymes that are naturally distributed in blood plasma/serum of animals and humans producing characteristic profile. This profile depends on intracellular isoenzyme concentration in all tissues that contribute to the common pool of lactate dehydrogenases in plasma/serum as a consequence of natural cell degradation. LDH is widely distributed in the body, high activities are found in the heart, liver, skeletal muscle, kidney, and erytrocytes, whereas lesser amounts are found in the lung, smooth muscle, and brain. Because of its widespread activities in numerous body tissues, LDH is elevated in a variety of disorders. There are many conditions that contribute to increased activity of LDH. An elevated total LDH value is a rather nonspecific finding. Therefore, LDH assays assume a more clinical significance when separated into isoenzyme fractions. The activity of LDH and its serum and tissue patterns and composition show great variations between the species. These differences do not allow using catalytic activities of LDH isoenzymes from one species to another. Instead, the pattern of serum LDH isoenzymes should be interpreted in respect to its species origin that is important in particular in veterinary medicine. Determination of total LDH activity and its isoenzyme pattern in serum of mammals had become one of the biochemical indicators in the assessment of organ disorders. When the content of cells is released from tissue to plasma, as on cell injury, the LDH isoenzyme pattern of the serum changes in favour of the profile of the affected organ (tissue) that can be used in the diagnostic practice.

The effect of candesartan on chronic stress induced imbalance of glucose homeostasis

OBJECTIVE

To explore whether chronic stress induces imbalance of glucose homeostasis, and to investigate the possible involvement of the renin-angiotensin system (RAS).

METHODS

Male Sprague-Dawley rats were divided into four groups: control, chronic stress, chronic stress plus low dose candesartan (an angiotensin II receptor-1 blocker, ARB, 5 mg/kg/d, i.p.), chronic stress plus high dose candesartan (15 mg/kg/d, i.p.). Rats were received restraint stress for 14 days. Glucose transporter 2 (GLUT2) mRNA was quantified in liver by real-time polymerase chain reaction. The concentration of glucokinase (GK), glucose-6-phosphatase (G-6-P), glycogen synthase (GS), insulin receptor (ISR), glucocorticoid receptor (GR)-alpha and -beta in liver, hexokinase (HK), lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH) in muscle, and serum insulin were measured by ELISA. Body weights, systolic blood pressure, heart rate and fasting blood glucose were monitored. Glucose tolerance test were performed after 14 days restraint stress.

RESULTS

After 14 days restraint stress, systolic blood pressure, increase of plasma glucose concentration at 15 minutes were higher and the fasting plasma concentration of glucose was lower compared with control group (P <  0.05), which were reversed by high dose ARB treatment (P <  0.05). In addition, chronic stress decreased expression of GLUT2 and increased expression of GR beta in liver. High dose ARB treatment normalized GLUT2 and GR beta expressions in liver.

CONCLUSIONS

Our present data indicate chronic stress induces the imbalance of glucose homeostasis and RAS contributes to the imbalance of glucose homeostasis induced by chronic stress.

Serum thymidine kinase activity as a useful marker for bovine leukosis

Serum thymidine kinase (TK) activity has recently been evaluated as a serum marker for human and canine hematopoietic neoplasms. The purpose of the current study was to establish the significance of serum TK activity in the diagnosis of bovine leukosis. The discrimination value for TK activity was set at 5.4 U/l based on the receiver operating characteristic curve. In the group of clinically healthy cows, only 2 out of 83 cows (2.4%) had serum TK activity above the discrimination value. In contrast, 19 out of 20 cows (95.0%) with bovine leukosis showed serum TK activity above the discrimination value, although only 7 of 79 (8.9%) cows diagnosed with diseases other than bovine leukosis showed elevated serum TK activity. Thymidine kinase activities of all Bovine leukemia virus-positive cows with or without lymphocytosis were below the discrimination value. Sensitivity and specificity of measuring serum TK activity as a diagnostic tool for bovine leukosis was 95.0% and 95.9%, respectively. Results indicate that serum TK activity may be a marker for bovine leukosis.

Changes in metabolite, energy metabolism related enzyme activities and peripheral blood mononuclear cell (PBMC) populations in beef heifers with two differing liveweight change profiles in New Zealand

Metabolite and immunoreactive insulin (IRI) concentrations, energy metabolism related enzymes activities and peripheral blood mononuclear cell (PBMC) populations were measured in blood of pregnant Angus heifers with differing liveweight change profiles (gaining or losing), in New Zealand to investigate the meanings of those parameters in the restricted feeding beef heifers. Beef heifers losing liveweight (-412 g/day) showed significantly lower concentrations of plasma IRI, and higher concentrations of plasma free fatty acid (FFA) than heifers gaining liveweight (483 g/day). The cytosolic and mitochondrial malate dehydrogenase (MDH) activities and MDH/lactate dehydrogenase (M/L) ratio in leukocytes of the liveweight losing heifers were significantly higher than those the liveweight gaining heifers. Percentages of cluster of differentiation (CD) 3 positive cells and natural killer (NK) cells in PBMC decreased significantly in the liveweight losing heifers compared to those in the liveweight gaining heifers. Plasma IRI and FFA concentrations, leukocyte cytosolic and mitochondrial MDH activities and CD3 positive and NK cell populations may be useful markers to evaluate metabolic conditions and immunity in the restricted feeding beef heifers.

Lactate dehydrogenase (LD) pattern in serum of calves with a total artificial heart (TAH)

Serum lactate dehydrogenase (LD) patterns of 16 calves with total artificial heart (TAH) were studied to identify a mean LD pattern in their serum (survival 51–293 days). Evaluations were made by the sum of vectors method (SV). The mean LD pattern was determined from serum LD patterns, interval days of 33 - 49 with TAH. Serum LD patterns of control and mean LD pattern differed significantly (n = 12, P < 0.05) in single isoenzymes and resultant vectors as the representatives of LD patterns. The different tissues with an increased risk of being affected were identified by evaluation of LD patterns in the serum of calves within term without perceptible acute damage and in the terminal stage of experiments. Such identified organs suggest that the organism under study is out of balance and specific treatment is needed.

Lactate dehydrogenase quantification and isoenzyme distribution in physiological response to stress in red deer (Cervus elaphus)

As a contribution to the description of the physiological response to stress in red deer (Cervus elaphus), the potential use of the intracellular glycolytic enzyme, lactate dehydrogenase (LDH) and its isoenzyme LDH-5, as a marker of muscle damage was assessed. The distribution of LDH isoenzymes within red deer tissues was similar to that shown in other ruminants: tissue characterisation showed isoenzyme LDH-5 to be particularly associated with skeletal muscle. High plasma concentrations of creatine kinase, a muscle-specific enzyme, were associated with both high total LDH activity and the percentage of LDH-5 activity in deer undergoing a potentially stressful procedure, transportation followed by simulated abattoir lairage, which is further evidence of the specificity of the isoenzyme for skeletal muscle damage. The activity of LDH was not correlated with the plasma concentration of cortisol, a widely used physiological measure of psychological stress. This may have been due to different time courses for release and the fact that, in the present study, the immediate pre-collection procedures may have induced a short-term stress response.

Experimental production of hypocalcemia by EDTA infusion in calves: a critical appraisal assessed from the profile of blood chemicals and enzymes

Physiological studies of the effects of Ca2+ withdrawal using Na2EDTA have been conducted with the prior basic assumption that Na2EDTA-specific direct or indirect effects on the functions under study were negligible. The present study aimed at providing unequivocal confirmation of such assumption by establishing the pattern of response of blood constituents to intravenous infusions of Na2EDTA in calves. Na2EDTA infusion in calves allowed effective chelation of blood Ca2+, leading to a progressive hypocalcemia. Magnesium levels remained constant and concentrations of other ions (Na+, K+, Pi, H+, HCO3-), although significantly altered (P < or = 0.0001), remained within the normal range. Comparison of enzymes, urea, and creatinine changes precluded renal, hepatic, or muscular parenchymatous damages as being the cause of dysfunctions in the context of Na2EDTA-induced hypocalcemia. It was not possible, however, to standardize the Na2EDTA infusion characteristics (flow, volume) to obtain previsible Ca2+ decay in different animals. Conversely, monitoring of systemic arterial pressure (SAP) offered a precious tool to estimate the degree of hypocalcemia reached. Infusion rate must, therefore, be manipulated using careful on-line monitoring of SAP to obtain an experimental range of Ca2+ as large as possible. It was concluded that physiological data collected during Na2EDTA perfusions can be reliably discussed in terms of Ca2+ dependence rather than in terms of either Na2EDTA toxicity, electrolytes maladjustment, acid-base imbalance, impaired blood oxygenation, or hepatic, renal, myocardic, or skeletal muscle damages.

Seasonal changes in the plasma isoenzymes of lactate: NADH oxidoreductase in Hereford cows under range conditions

Plasma levels of lactate: NADH oxidoreductase (LD) and the proportions of five major isoenzymes were estimated in samples taken in January, March, June, July and November from Hereford cows kept under range conditions. Seasonal changes were observed in both total LD and the proportions of the isoenzymes. Levels of total LD and all isoenzymes were low in winter and high in summer. Proportions of LD4 and LD5, the electrophoretically slow isoenzymes which predominate in muscle, increased in summer at the expense of LD1, the fast isoenzyme which predominates in liver and erythrocytes. LD1 was increased in November, at the time when other isoenzyme levels were decreasing from summer high levels. The seasonal changes observed in plasma LD were attributed to changes in diet and/or water supply and activity of the range cows.

The mechanisms relating to increases in plasma enzymes and isoenzymes in diseases of animals

Changes in plasma or serum enzymes and isoenzymes are useful indicators of tissue damage in many diseases. Enzyme increases are usually related to leakage of enzymes from damaged cells. The amount of increase depends on factors such as the concentration of enzyme in the cells, the rate of leakage of enzyme from cells and the rate of clearance of enzyme from plasma. There are important species variations in the tissue concentrations and plasma clearance rates of enzymes and isoenzymes.

One and two dimensional isoelectric focusing of lactate dehydrogenase from the tissues of ovis aries

Lactate dehydrogenase in ovine tissues was separated by electrophoresis, one dimensional isoelectric focusing (IEF) and a two dimensional technique. Tissues showed five zones of enzyme activity consisting of multiple bands after IEF. The IEF zymograms were unique for each tissue and differed from those of other species. Two dimensional separation revealed that the five zones of activity observed on IEF corresponded to the five isoenzymes separable by conventional electrophoresis.

Sources of normal variation of plasma lactate dehydrogenase in range cattle

1. Plasma levels of lactate dehydrogenase (LD) were estimated in Hereford cattle of 1 month to 12 yr of age kept under range conditions. 2. Plasma levels of LD were estimated in a group of confined cows and their calves fed a constant diet and kept in individual pens in the same geographic area as the range Herefords. 3. Large seasonal changes in mean plasma LD were observed in the range cattle but not in the confined, constant diet group. The seasonal changes corresponded with the appearance of new growth on the range. 4. Changes in plasma LD were observed at weaning time in the range cattle but not in the confined group. 5. Sex had no effect upon plasma LD levels in the juvenile animals of either group. No comparison of adult animals could be made. 6. Mean plasma LD levels did not change with age but the seasonal effect decreased in magnitude as the animals matured. 7. An increase in plasma LD was observed around the first ovulation in the confined animals. 8. A decrease in plasma LD was observed during parturition in the confined group.