Does sex matter in the cheetah? Insights into the skeletal muscle of the fastest land animal.

The cheetah is considered the fastest land animal, but studies on their skeletal muscle properties are scarce. Vastus lateralis biopsies, obtained from male and female cheetahs as well as humans, were analysed and compared for fibre type and size, and metabolism. Overall, cheetah muscle had predominantly type IIX fibres, which was confirmed by the myosin heavy chain isoform content (type I: 17±8%, type IIA: 21±6%, type IIX: 62±12%), whereas humans contained predominantly type I and IIA fibres (type I: 49±14%, type IIA: 43±8%, type IIX: 7±7%). Cheetahs had smaller fibres than humans, with larger fibres in the males compared to their female counterparts. Citrate synthase (16±6 vs. 28±7 µmol/min/g prot, P<0.05) and 3-hydroxyacetyl co-enzyme a dehydrogenase (30±11 vs. 47±15 µmol/min/g prot, P<0.05) activities were lower in cheetahs, whereas lactate dehydrogenase activity was 6 times higher in cheetahs (2159±827 vs. 382±161 µmol/min/g prot, P<0.001). The activities of creatine kinase (4765±1828 vs. 6485±1298, P<0.05 µmol/min/g prot) and phosphorylase (111±29 vs. 216±92 µmol/min/g prot) were higher in humans, irrespective of higher type IIX fibres in cheetahs. Superoxide dismutase and catalase, markers of antioxidant capacity, were higher in humans, but overall antioxidant capacity was higher in cheetahs. To conclude, fibre type, fibre size and metabolism differ between cheetahs and humans, with limited differences between the sexes.

A cross-over dietary intervention in captive cheetahs (Acinonyx jubatus): Investigating the effects of glycine supplementation on blood parameters.

Captive cheetahs are prone to unusual diseases which may be attributed to their high muscle meat, collagen deficient captive diet. Glycine is a simple amino acid that is abundant in collagen rich tissues and has many physiological functions, specifically in collagen synthesis and in the conjugation of detrimental by-products produced during gut bacterial fermentation. Therefore, the aim of this study was to investigate the effect of a 4 week glycine supplementation on the body measurements, haematology and serum blood parameters of 10 captive cheetahs using a randomised controlled cross-over design. This approach has not yet been used to investigate the effect of diet in captive cheetahs. Cheetahs were randomly assigned to a control diet (horse meat only) or a glycine diet (30 g glycine per 1 kg meat) for 4 weeks before being crossed over. Blood was collected at baseline and after each intervention. The glycine diet resulted in a decreased serum albumin, alkaline phosphatase and total calcium concentration and increases in eosinophils and basophils counts compared to the control diet. Body weight also decreased on the glycine diet which may be due to increased ß-oxidation and fat loss. This was the first study to investigate the effect of glycine supplementation, which resulted in slight body and blood changes, in captive cheetahs using a cross-over design and this approach should be utilised for future dietary studies.

Wild antelope skeletal muscle antioxidant enzyme activities do not correlate with muscle fibre type or oxidative metabolism.

Wild antelope are some of the fastest land animals in the world, presenting with high oxidative and glycolytic skeletal muscle metabolism. However, no study has investigated their muscle antioxidant capacity, and may assist in understanding their physical ability and certain pathophysiological manifestations, such as capture myopathy. Therefore, the primary aim of this study was to determine the antioxidant activities superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR), as well as five key regulatory enzymes that serve as markers of glycolysis (phosphofructokinase (PFK) and lactate dehydrogenase (LDH)), the tricarboxylic acid cycle (citrate synthase (CS)), ß-oxidation (3-hydroxyacetyl CoA dehydrogenase (3HAD)) and the phosphagen pathway (creatine kinase (CK)), in the Vastus lateralis muscle of six southern African wild antelope species (mountain reedbuck, springbok, blesbok, fallow deer, black wildebeest and kudu). Four different muscle groups from laboratory rats served as reference values for the enzyme activities. SOD, CS and LDH activities were the highest in the wild antelope, whereas CK appeared highest in rat fast twitch muscles. Between the wild antelope species, differences exist for SOD, CAT, PFK, CK and LDH, but not for CS, 3HAD and GR. CAT and GR correlated positively only with type I fibres. No correlations could be found between muscle fibre type and the oxidative enzymes, CS and 3HAD, from the wild animals, concurring with previous studies on porcine and rats. However, wild antelope and rat muscle CK and SOD strongly correlated, hinting towards an antioxidant role for CK.

Are Cape Peninsula baboons raiding their way to obesity and type II diabetes? - a comparative study.

Researchers, managers and conservationists in the Cape Peninsula, South Africa, have reported cases of individual baboons (Papio ursinus) appearing overweight, lethargic and having poor teeth. Despite an intensive baboon management programme, there are certain individual baboons and troops that continue to raid human food sources. These food sources often are high in processed carbohydrates and saturated fats. As this diet is highly associated with obesity, insulin resistance and type II diabetes, the present study aimed to establish if these baboons may be at risk of developing insulin resistance. Post mortem muscle samples from 17 Cape Peninsula and 7 control adult male baboons were rapidly frozen in liquid nitrogen and analysed for insulin receptor substrate-1 (IRS-1), glucose transporter 4 (GLUT4), oxidative and glycolytic markers of metabolism (citrate synthase, 3-hydroxyacyl-CoA-dehydrogenase, lactate dehydrogenase and creatine kinase activities), and muscle fibre morphology. The sampled Peninsula baboons were heavier (33 ± 2 vs. 29 ± 2 kg, P < 0.05) and had a higher frequency of poor teeth compared to control baboons. Muscle fibre type, fibre size, GLUT4 content, oxidative and glycolytic metabolism were not different between the two groups. However, IRS-1 content, a marker of insulin sensitivity, was significantly lower (by 43%, P < 0.001) in the Peninsula baboons compared to the controls. This study provides the first indirect evidence that some Peninsula baboons with a history of raiding human food sources, may be at risk of developing insulin resistance in the wild, with long term implications for population health.

Reduced Glucose Tolerance and Skeletal Muscle GLUT4 and IRS1 Content in Cyclists Habituated to a Long-Term Low-Carbohydrate, High-Fat Diet.

Very little is known about how long-term (>6 months) adaptation to a low-carbohydrate, high-fat (LCHF) diet affects insulin signaling in healthy, well-trained individuals. This study compared glucose tolerance; skeletal muscle glucose transporter 4 (GLUT4) and insulin receptor substrate 1 (IRS1) content; and muscle enzyme activities representative of the main energy pathways (3-hydroxyacetyl-CoA dehydrogenase, creatine kinase, citrate synthase, lactate dehydrogenase, phosphofructokinase, phosphorylase) in trained cyclists who followed either a long-term LCHF or a mixed-macronutrient (Mixed) diet. On separate days, a 2-hr oral glucose tolerance test was conducted, and muscle samples were obtained from the vastus lateralis of fasted participants. The LCHF group had reduced glucose tolerance compared with the Mixed group, as plasma glucose concentrations were significantly higher throughout the oral glucose tolerance test and serum insulin concentrations peaked later (LCHF, 60 min; Mixed, 30 min). Whole-body insulin sensitivity was not statistically significantly different between groups (Matsuda index: LCHF, 8.7 ± 3.4 vs. Mixed, 12.9 ± 4.6; p = .08). GLUT4 (LCHF: 1.13 ± 0.24; Mixed: 1.44 ± 0.16; p = .026) and IRS1 (LCHF: 0.25 ± 0.13; Mixed: 0.46 ± 0.09; p = .016) protein content was lower in LCHF muscle, but enzyme activities were not different. We conclude that well-trained cyclists habituated to an LCHF diet had reduced glucose tolerance compared with matched controls on a mixed diet. Lower skeletal muscle GLUT4 and IRS1 contents may partially explain this finding. This could possibly reflect an adaptation to reduced habitual glucose availability rather than the development of a pathological insulin resistance.

A pyruvate decarboxylase-mediated therapeutic strategy for mimicking yeast metabolism in cancer cells.

Cancer cells have high rates of glycolysis and lactic acid fermentation in order to fuel accelerated rates of cell division (Warburg effect). Here, we present a strategy for merging cancer and yeast metabolism to remove pyruvate, a key intermediate of cancer cell metabolism, and produce the toxic compound acetaldehyde. This approach was achieved by administering the yeast enzyme pyruvate decarboxylase to triple negative breast cancer cells. To overcome the challenges of protein delivery, a nanoparticle-based system consisting of cationic lipids and porous silicon were employed to obtain efficient intracellular uptake. The results demonstrate that the enzyme therapy decreases cancer cell viability through production of acetaldehyde and reduction of lactic acid fermentation.

Evaluation of anticancer activity of celastrol liposomes in prostate cancer cells.

CONTEXT: Celastrol, a natural compound derived from the herb Tripterygium wilfordii, is known to have anticancer activity, but is not soluble in water. OBJECTIVE: Formation of celastrol liposomes, to avoid the use of toxic solubilising agents. MATERIALS AND METHODS: Two different formulations of PEGylated celastrol liposomes were fabricated. Liposomal characteristics and serum stability were determined using dynamic light scattering. Drug entrapment efficacy and drug release were measured spectrophotometrically. Cellular internalisation and anticancer activity was measured in prostate cancer cells. RESULTS: Liposomal celastrol displayed efficient serum stability, cellular internalisation and anticancer activity, comparable to that of the free drug reconstituted in dimethyl sulfoxide. DISCUSSION AND CONCLUSION: Liposomal celastrol can decrease the viability of prostate cancer cells, while eliminating the need for toxic solubilising agents.

Hesperetin impairs glucose uptake and inhibits proliferation of breast cancer cells.

The flavanone hesperetin is known to decrease basal glucose uptake, although the inhibitory mechanism is largely unknown. Here, we used MDA-MB-231 breast cancer cells to investigate the molecular pathways affected by hesperetin. The results indicate that the suppression of glucose uptake is caused by the down-regulation of glucose transporter 1 (GLUT1). Hesperetin was also found to inhibit insulin-induced glucose uptake through impaired cell membrane translocation of glucose transporter 4 (GLUT4). In addition, the phosphorylation of the insulin receptor-beta subunit (IR-beta) and Akt was suppressed. Hesperetin also decreased cellular proliferation, which is likely due to the inhibition of glucose uptake. Cancer cells are highly dependent on glucose and hesperetin may, therefore, have potential application as an anticancer agent.

Fiber type and metabolic characteristics of skeletal muscle in 16 breeds of domestic dogs.

The domestic dog (Canis lupus familiaris) species comprises hundreds of breeds, each differing in physical characteristics, behavior, strength, and running capability. Very little is known about the skeletal muscle composition and metabolism between the different breeds, which may explain disease susceptibility. Muscle samples from the triceps brachii (TB) and vastus lateralis (VL) were collected post mortem from 35 adult dogs, encompassing 16 breeds of varying ages and sex. Samples were analyzed for fiber type composition, fiber size, oxidative, and glycolytic metabolic capacity (citrate synthase [CS], 3-hydroxyacetyl-coA dehydrogenase [3HAD], creatine kinase [CK], and lactate dehydrogenase [LDH] enzyme activities). There was no significant difference between the TB and VL in any of the measurements. However, there were large intra species variation, with some variables confirming the physical attributes of a specific breed. Collectively, type IIA was the predominant fiber type followed by type I and type IIX. The cross-sectional areas (CSA) of the fibers were all smaller when compared to humans and similar to other wild animals. There was no difference in the CSA between the fiber types and muscle groups. Metabolically, the muscle of the dog displayed high oxidative capacity with high activities for CS and 3HAD. Lower CK and higher LDH activities than humans indicate a lower and higher flux through the high energy phosphate and glycolytic pathways, respectively. The high variability found across the different breeds may be attributed to genetics, function or lifestyle which have largely been driven through human intervention. This data may provide a foundation for future research into the role of these parameters in disease susceptibility, such as insulin resistance and diabetes, across breeds.

A novel description of the Vastus lateralis morphology of the Temminck's ground pangolin (Manis temminckii).

The pangolin (Manidae family) is the world's most trafficked animal, yet very little is known about its physiology and metabolism primarily due to its inconspicuous and solitary nature. Skeletal muscle samples from the Vastus lateralis were collected postmortem from a single female Temminck's ground pangolin (Manis temminckii). Samples were analyzed for fiber type composition, fiber size and myosin heavy chain isoform content. The oxidative and glycolytic metabolic capacity was determined through citrate synthase, 3-hydroxyacetyl co A dehydrogenase, creatine kinase, lactate dehydrogenase, phosphofructokinase and glycogen phosphorylase enzyme activities. Lastly, antioxidant capacity was determined through superoxide dismutase and catalase enzyme activities, and the total antioxidant capacity. The pangolin metabolic profile was then compared to other endurance and nonendurance mammals, in which data were standardized relative to human endurance athletes in order to provide context. Slow twitch type I fibers, rich in mitochondria were the predominant fiber type within the pangolin indicating a reliance on oxidative derived energy from fats and carbohydrates. This suggests that the pangolin has a high endurance capability when compared to other wild animals and human endurance athletes. This is the first study to investigate the skeletal muscle physiology and metabolism of any pangolin species, in an attempt to further understand this endangered animal and aid with conservation efforts.

Hesperetin Liposomes for Cancer Therapy.

Hesperetin is a compound from citrus fruit that has previously been found to exert anticancer activity through a variety of mechanisms. However, the application of hesperetin to cancer therapy has been hampered by its hydrophobicity, necessitating the use of toxic solubilizing agents. Here, we have developed the first liposome-based delivery system for hesperetin. Liposomes were fabricated using the thin-layer evaporation technique and physical and pharmacological parameters were measured. The liposomes remained stable for prolonged periods of time in serum and under storage conditions, and displayed anticancer efficacy in both H441 lung cancer cells and MDA-MB-231 breast cancer cells. Furthermore, the anticancer activity was not impaired in cells expressing the multidrug resistance protein 1 (MDR-1). In conclusion, the encapsulation of hesperetin in liposomes does not interfere with therapeutic efficacy and provides a biocompatible alternative to toxic solubilizing agents, thereby enabling future clinical use of this compound for cancer therapy.