Laparoscopic ovariohysterectomy for dogs under 5 kg body weight.

OBJECTIVE: To describe the surgical method, operative time, safety, and usefulness of 3-port laparoscopic ovariohysterectomy (LOHE) using an ultrasonic coagulation and incision device in dogs <5 kg. STUDY DESIGN: Retrospective study. ANIMALS: Female dogs (n = 147). METHODS: Animals were allocated to one of four groups by bodyweight: <2 kg (n = 18), 2-3 kg (n = 37), 3-4 kg (n = 55), and 4-5 kg (n = 37). All surgical procedures were recorded on video. Mean operative time (i.e., time from first skin incision to last suture), clinical variables, hematologic variables, and blood biochemistry were recorded. Intrasurgical and postsurgical complications were recorded, and wound complications, including signs of inflammation or hernia formation were monitored for 3 months. RESULTS: The mean operative time for all groups was 18 min, with no significant differences between groups. Eight dogs bled from the mesometrium during surgery. Two dogs had hernia formation at a midline port incision; this complication developed by month 3. No complications such as wound dehiscence or infection of the surgical field were observed at the time of suture removal in any of the dogs. CONCLUSION: We performed LOHE using an ultrasonic coagulation and incision device in dogs <5 kg, and found it to be a safe procedure with minimal complications. CLINICAL SIGNIFICANCE: We believe that LOHE, using a 3-port and ultrasonic coagulation and incision device, is a safe, useful, and minimally invasive surgical method for sterilization of dogs <5 kg with minimal complications.

Enhancement of reactive oxygen species and induction of apoptosis in streptozotocin-induced diabetic rats under hyperbaric oxygen exposure.

An important source of reactive oxygen species (ROS) production is nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, which on activation induces superoxide production via oxidation in the mitochondria, inflammation and stress; such ROS are implicated in the pathogenesis of diabetic complications, including neuropathy. Hyperbaric oxygen (HBO) treatments are applied various diseases including diabetic patients with unhealing foot ulcers, however, and also increases the formation of ROS. In a previous study, we showed that a clinically recommended HBO treatment significantly enhanced oxidative stress of pancreatic tissue in the diabetic rats. However, no study has been undertaken with regard to the effects of HBO on the activity and gene expression of the NADPH oxidase complex and on apoptosis in the pancreas of diabetic animals. The purpose of this study was to investigate the effect of HBO exposure on gene expression of the NADPH complex, and pancreatic expression of genes related to apoptosis via the mitochondria, using the NADPH oxidase inhibitor apocynin. The mRNA expression of genes related to NADPH oxidase complex and apoptosis increased significantly (P < 0.05) in the pancreas of diabetic rats under HBO exposure. Similarly, activities of NADPH oxidase and caspase-3 changed in parallel with mRNA levels. These results suggest that oxidative stress caused by HBO exposure in diabetic animals induces further ROS production and apoptosis, potentially through the up-regulation of NADPH oxidase complex. Thus, this study can contribute to development of a better understanding of the molecular mechanisms of apoptosis via the mitochondria in diabetes, under HBO exposure.

Regulation of synthesis and oxidation of fatty acids by adiponectin receptors (AdipoR1/R2) and insulin receptor substrate isoforms (IRS-1/-2) of the liver in a nonalcoholic steatohepatitis animal model.

Nonalcoholic steatohepatitis (NASH) is one of the most frequent causes of abnormal liver dysfunction associated with synthesis and oxidation of fatty acids. Adiponectin receptors (AdipoR1/R2) and insulin receptor substrates (IRS-1/-2) are known as modulators of these fatty acid metabolisms in the liver; however, the regulatory roles of these receptors in the synthesis and oxidation of fatty acids are unclear in the liver of NASH. In this study, we examined the roles of hepatic AdipoR1/R2 and IRS-1/-2 in NASH using an animal model. After feeding a high-fat and high-cholesterol diet to obese fa/fa Zucker rats for 8 weeks, rats showed fatty liver spontaneously with inflammation and fibrosis that are characteristic of NASH. The expression levels of AdipoR1/R2 and IRS-2 were significantly decreased, whereas IRS-1 was significantly increased, in NASH. As a result of the decrease of AdipoR1/R2 expression, the messenger RNA expression levels of genes located downstream of AdipoR1/R2, adenosine monophosphate-activated protein kinase α1/α2, which inhibits fatty acid synthesis, and peroxisome proliferator-activated receptor α, which activates fatty acid oxidation, also decreased. Expression level of sterol regulatory element binding protein-1c was found to be elevated, suggesting the up-regulation of IRS-1, and resulted in increased fatty acid synthesis. Furthermore, increase of forkhead box protein A2 expression was observed, which might be associated with the down-regulation of IRS-2, facilitating fatty acid oxidation. Taken together, increased synthesis and oxidation of fatty acids by up- or down-regulation of AdipoR or IRS may contribute to the progression of NASH. Thus, AdipoR and IRS might be crucially important regulators for the synthesis and oxidation of fatty acids in the liver of NASH.

Regulation of oxidative stress and inflammation by hepatic adiponectin receptor 2 in an animal model of nonalcoholic steatohepatitis.

The pathogenesis of nonalcoholic steatohepatitis (NASH) is not well understood; however, the progression of fatty liver to NASH has been linked to oxidative stress and lipid peroxidation in the liver, leading to inflammation. Although the adiponectin receptor 2 (AdipoR2) has been identified as a modulator of oxidative stress and inflammation in the liver, it remains unclear whether the receptor has hepatic antioxidant and anti-inflammatory effects in NASH. In this study, we used an animal model of NASH to examine hepatic AdipoR2. Obese fa/fa Zucker rats fed a high-fat and high-cholesterol (HFC) diet spontaneously developed fatty liver with inflammation and fibrosis, characteristic of NASH, after 4, 8, or 12 weeks of HFC diet consumption. AdipoR2 expression was significantly decreased, whereas the expression of genes related to NADPH oxidase complex were increased. As a result of the decrease in AdipoR2 expression, the mRNA expression of genes located downstream of AdipoR2, i.e., Cu-Zn superoxide dismutase (Cu-Zn SOD) and Mn-SOD, also decreased. Furthermore, the expression of genes related to inflammation was increased. Increased oxidative stress and inflammation by down-regulation of AdipoR2 may contribute to the progression of NASH. Thus, the AdipoR2 might be a crucially important regulator of hepatic oxidative stress and inflammation in NASH.

Oxidative stress and gene expression of antioxidant enzymes in the streptozotocin-induced diabetic rats under hyperbaric oxygen exposure.

Diabetes mellitus (DM) causes not only hyperglycemia but oxidative stress, resulting mainly enhanced production of mitochondrial reactive oxygen species (ROS). Hyperbaric oxygen (HBO) treatments are applied various diseases including diabetic patients with unhealing foot ulcers, however, and also increases the formation of ROS. Recently, it has been reported that oxidative stress worsens many pathological conditions including DM and obesity suggesting possible changes in regulation of genes associated with the oxidative stress, however, effects of HBO which could induce ROS on the gene expressions of oxidative stress parameters in DM animals are unknown. The purpose of this study is to investigate the effect of HBO exposure on the gene expression of three important antioxidant enzymes, cytosolic superoxide dismutase (Cu-Zn SOD), cytosolic glutathione peroxidase (GPx-1), and catalase (CAT) in DM rats, respectively. We used streptozotocin-induced DM model rats and examined both mRNA expressions and the activities of these antioxidant enzymes in the liver, skeletal muscle, and pancreas. The mRNA expressions of Cu-Zn SOD and CAT decreased significantly (p < 0.001), and GPx increased significantly (p < 0.001) in all the studied organs of DM rats under HBO exposure compared to those from DM-induced rats not exposed to HBO. Similarly, activities of these three enzymes changed in accordance with the mRNA levels. These results suggested that DM induction and HBO exposure might synergistically affect antioxidant enzymes, resulting increase of oxidative stress state. Thus, HBO exposure seems to be an excellent model system for investigating oxidative stress.

Enhancement of glucose toxicity by hyperbaric oxygen exposure in diabetic rats.

The side effects of hyperbaric oxygen (HBO) treatment, such as oxidative stress and oxygen toxicity, have long been of interest. However, there are no comprehensive studies evaluating such toxic effects in diabetes mellitus (DM). The purpose of this study was to determine the effects of HBO on glucose homeostasis and histological changes in pancreatic beta-cells of experimentally induced diabetic rats. A total of 24 male Wistar rats were randomly divided into 4 groups: 1) Control group, no diabetic induction without HBO treatment; 2) HBO group, exposed to 100% oxygen at 2.8 ATA (atmosphere absolute) for 2 h once daily, for 7 days; 3) DM group, diabetes induced by streptozotocin (STZ) injection; and 4) DM + HBO group, received both STZ injection and HBO exposure. HBO treatment, with clinically recommended pressures and duration of therapy, was started on day 5 after STZ injection, when the blood glucose levels were significantly increased. After the last HBO treatment, the pancreatic tissues were immunostained to measure the areas of insulin immunoreactive beta-cells in the islets of Langerhans. The blood glucose increased significantly following exposure to HBO, with the highest levels achieved in rats, which had been treated with both HBO and diabetic induction. The area populated with insulin immunoreactive beta-cells decreased significantly following diabetic induction and/or HBO exposure, with the smallest area in DM + HBO group. Thus, HBO exposure enhanced the cytotoxic effect of STZ in the beta-cells of the pancreas. HBO should be cautiously employed in diabetic patients.