Postprandial lipemia causes oxidative stress in dogs

Ozone therapy by rectal insufflation in dogs: safety and oxidative stress - a randomized cross-over study

Ozone therapy acts in the body inducing controlled oxidative stress, thereby improving the antioxidant, immune and circulatory responses. However, very little is known about how this therapy affects oxidative stress indicators in dogs. We aimed to assess the clinical, hematological, biochemical and oxidative stress parameters of healthy dogs subjected to ozone therapy and oxygen therapy by rectal insufflation. Ten healthy dogs were allocated into three experimental groups in a cross-over design: control, without intervention; ozone, which received 100 µg of O3/kg through rectal insufflation; and oxygen, which received an ozone-equivalent volume of medicinal O2 through rectal insufflation. Dogs received four applications weekly and were followed up until the seventh week. Ozone therapy significantly increased the weight, mean corpuscular volume and mean platelet volume and decreased total cholesterol of treated dogs. Regarding oxidative stress, ozone therapy reduced total antioxidant capacity by ferric reduction (TAC-FRAP) in D7 compared with baseline and the control, significantly increased total antioxidant capacity by cupric reduction (TAC-CUPRAC) in D42 and D49 compared with the control group, caused an increase in uric acid compared with the oxygen group and decreased lipid peroxidation on D21 compared with the control group. In conclusion, ozone therapy through rectal insufflation causes transient oxidative stress followed by an antioxidant response and discreetly interferes with a few clinical, hematological and biochemical variables in healthy dogs, although variables still remained within the reference ranges for the species, thus proving the safety of the therapy. Furthermore, oxygen therapy causes oxidative stress without inducing a subsequent antioxidant response.

Hemolysis, icterus and lipemia interfere with the determination of two oxidative stress biomarkers in canine serum

BACKGROUND

Oxidative stress has been proven to play a role in numerous human and canine diseases. Among the biomarkers of oxidative stress, Thiobarbituric Acid Reactive Substances (TBARS) and Total Antioxidant Status (TAS) are two of the most widely used. Preanalytical factors are crucial for obtaining accurate results in these assays. Hemolysis, icterus and lipemia (HIL) are common sources of preanalytical errors in the laboratory; however, limited information is available regarding the considerations for canine specimens. Therefore, the objective of this study was to evaluate the potential interferences of HIL in the determination of TBARS and TAS in canine serum.

METHODS

Solutions of pooled canine serum samples were prepared by adding increasing concentrations of hemolysate, bilirubin and a synthetic lipid emulsion. TBARS and TAS were determined, and biases from the control value caused by the interfering substances were calculated.

RESULTS

Hemolysis, icterus and lipemia induced significant interferences on TBARS and TAS, albeit to varying degrees depending on the specific biomarker and interfering substance. TBARS appeared to be more susceptible to interferences in this study. Slight hemolysis, moderate icterus and slight lipemia caused notable deviations in TBARS values, surpassing the acceptable threshold for interference. TAS assay was also affected by HIL, although to a lesser extent compared to TBARS. Significant biases from TAS control value were observed when icterus was moderate, and when hemolysis and lipemia were more pronounced.

CONCLUSIONS

In light of our results, we conclude that hemolyzed, icteric and lipemic specimens are not suitable for TBARS and TAS determination in canine serum. Our findings hold considerable practical utility, as a simple visual inspection would be sufficient for identifying and excluding such specimens.

A bibliometric analysis and visualization of literature on non-fasting lipid research from 2012 to 2022

Background

Non-fasting lipid assessment can help predict cardiovascular disease risks and is linked to multiple diseases, particularly diabetes. The significance of non-fasting lipid levels in routine screening and postprandial lipid tests for potential dyslipidemia has not been conclusively determined. Various new lipid-lowering strategies have been developed to improve non-fasting dyslipidemia. Therefore, analysis of scientific outputs over the past decade is essential to reveal trends, hotspots, and frontier areas for future research in this field.

Methods

The Science Citation Index Expanded in the Web of Science Core Collection database was searched for publications related to non-fasting lipid research from 2012 to 2022. The regional distributions, authors, disciplines, journals, references, and keywords of the studies were analyzed using the bibliometric software VOSviewer and CiteSpace.

Results

A total of 4160 articles and reviews that met the inclusion criteria were included in this study. The output trend was established to be stable and the number of citation indices has been persistently increasing. A total of 104 countries/regions, 4668 organizations, and 20782 authors were involved in this research area. In terms of country, the United States had the largest number of publications (979). The University of Copenhagen was the most productive institution, publishing 148 papers. Professor Børge G Nordestgaard has made the most significant contribution to this field. Nutrients was the most productive journal while the American Journal of Clinical Nutrition was the highest co-cited journal. Analysis of co-cited references indicated that lipid-lowering strategies, statin therapy, high-fat meals, insulin resistance, physical exercise, and fructose were hotspots. Analysis of co-cited keywords revealed that apolipoprotein B, especially apolipoprotein B48, is becoming a key research focus. The keywords "gut microbiota" and "meal timing" were the most extensively studied.

Conclusion

The causal relationship between non-fasting dyslipidemia and diseases is currently being explored and the standards for non-fasting or postprandial lipid assessment are continuously being updated. Among the hotspots, lipid-lowering strategies are a potential research direction. Apolipoprotein B48, gut microbiota, and chrononutrition are the research frontiers. This initial bibliometric analysis of non-fasting lipids will enable researchers to monitor swift transformations and recognize novel concepts for upcoming research.

Feline obesity causes hematological and biochemical changes and oxidative stress - a pilot study

Obesity, an extremely important factor in feline clinical practice, is estimated to affect up to one third of the feline population. Moreover, it can trigger chronic inflammation, which could predispose to oxidative stress by increasing reactive oxygen species, thereby generating potentially irreversible cellular damage. This study analyzed hematological, biochemical and oxidative stress profiles at various degrees of feline obesity. Forty-five cats were selected and divided into three groups: control (n = 17), overweight (n = 13) and obese (n = 15), after clinical and laboratory evaluation and body condition score. Biochemical and oxidative stress analyses were performed using a photocolorimeter and hematological analyses were performed in a veterinary cell counter. Obese cats showed increased mean corpuscular volume (MCV), red cell distribution width (RDW), HDL cholesterol and triglycerides and decreased activity of gamma-glutamyl transferase (GGT) than control cats, although within the reference ranges for the species. As for oxidative stress, obese cats showed higher total antioxidant capacity (TAC), by the inhibition of 2,2'-Azino-Bis-3-Ethylbenzthiazoline-6-Sulfonic Acid (ABTS), inhibition of ABTS associated with horseradish peroxidase (ABTS + HRP), cupric ion reducing antioxidant capacity (CUPRAC) and ferric reducing antioxidant power (FRAP) methods, while overweight cats had a higher TAC-ABTS + HRP and TAC-FRAP than control cats. We conclude that the conditions of natural obesity and overweight in the feline species alter its hematological, biochemical and oxidative stress parameters.

Does postprandial lipemia interfere with blood gas analysis and assessment of acid-base status in dogs?

To evaluate the interference of postprandial lipemia on blood gas parameters and to assess the acid-base status by the quantitative approach of the strong ion model blood samples of 15 healthy dogs were collected during fasting (0 h) and at one (1 h), three (3 h) and five (5 h) hours after the induction of lipemia with a hypercaloric diet. Total cholesterol (TC) and triglyceride (TG) levels were used to assess lipemia and these were correlated with the parameters evaluated accordingly. Anion gap decreased at 5 h without correlation with TC and TG, whereas other parameters measured by the blood gasometer did not change. In the evaluation of the acid base state, the apparent strong ion difference (SIDa) and the strong ion gap (SIG) showed a decrease at 5 h without correlation with lipemia. Lipid levels correlated with the effective strong ion difference (SIDe), the concentration of total non-volatile weak acids (A_tot), albumin, phosphate, and magnesium. The SIDe increased at 1 h and at 3 h; the A_tot at 1 h, 3 h, and 5 h; albumin increased at 1 h and 3 h; phosphate increased at 1 h, 3 h and 5 h; and magnesium decreased at 5 h. Though postprandial lipemia does not interfere with blood gas analysis, it can cause errors in the variables used to assess the acid-base status, which are dependent on biochemical analytes. Therefore, caution is required when interpreting electrolyte disturbances that result from the postprandial state.

Species Differences in Tryptophan Metabolism and Disposition

Major species differences in tryptophan (Trp) metabolism and disposition exist with important physiological, functional and toxicity implications. Unlike mammalian and other species in which plasma Trp exists largely bound to albumin, teleosts and other aquatic species possess little or no albumin, such that Trp entry into their tissues is not hampered, neither is that of environmental chemicals and toxins, hence the need for strict measures to safeguard their aquatic environments. In species sensitive to toxicity of excess Trp, hepatic Trp 2,3-dioxygenase (TDO) lacks the free apoenzyme and its glucocorticoid induction mechanism. These species, which are largely herbivorous, however, dispose of Trp more rapidly and their TDO is activated by smaller doses of Trp than Trp-tolerant species. In general, sensitive species may possess a higher indoleamine 2,3-dioxygenase (IDO) activity which equips them to resist immune insults up to a point. Of the enzymes of the kynurenine pathway beyond TDO and IDO, 2-amino-3-carboxymuconic acid-6-semialdehyde decarboxylase (ACMSD) determines the extent of progress of the pathway towards NAD⁺ synthesis and its activity varies across species, with the domestic cat (Felis catus) being the leading species possessing the highest activity, hence its inability to utilise Trp for NAD⁺ synthesis. The paucity of current knowledge of Trp metabolism and disposition in wild carnivores, invertebrates and many other animal species described here underscores the need for further studies of the physiology of these species and its interaction with Trp metabolism.

Evaluation of hematological, biochemical and oxidative stress profile in calves under propofol anesthesia

Propofol is a widely used drug in veterinary medicine to induce anesthesia; as well as the chosen compound for protocols of intravenous anesthesia. The present study aimed to describe the hematological, biochemical and oxidative stress alterations in calves kept under anesthesia by propofol in different dosages. In order to achieve this, eight Holstein calves were induced using propofol in a 5 mg/kg dosage and maintained under continuous propofol infusion for 60 min, having being administered 0.6 mg/kg/h or 0.8 mg/kg/h in crossover design with seven days interval. Blood samples were collected immediately before the anesthesia induction (baseline), and 30 min, 1, 2, 3, 4 and 5 h after the procedure started. Statistically relevant propofol influence was observed both in blood and biochemical parameters, with differences between dosages according to the time of infusion. The drug action over oxidative stress was also observed, causing a raise of the total antioxidant capacity (TAC) with an uric acid increase. Additionally, the increase of triglycerides, induced by the anesthesia maintenance with propofol, caused lipemia in the samples, which was capable of interfering directly in the measurements made by refractometry and spectrophotometry. It was concluded that, in spite of propofol induced alterations in blood and biochemical parameters, such alterations are subtle. In addition to that, the drug presented an antioxidative effect, which reinstates the safety of anesthesia maintenance with propofol in calves.