Expression of adiponectin receptors in pancreatic beta cells

Pancreatic beta cell dysfunction is an early and crucial pathogenic factor in the development of type 2 diabetes. Free fatty acids (FFA) and adipokines released from adipose tissues lead to both the development of insulin resistance and beta cell dysfunction. Adiponectin is a novel adipokine with antidiabetic properties. Its circulating concentrations are reduced in subjects with increased visceral adiposity, insulin resistance, or type 2 diabetes. Very recently, the cloning of two adiponectin receptors AdipoR1 and AdipoR2 was reported. AdipoR1 is abundantly expressed in muscle, while AdipoR2 is predominantly expressed in liver. Here we report the marked expression of mRNAs for the adiponectin receptors AdipoR1 and AdipoR2 in human and rat pancreatic beta cells, at levels similar to liver and greater than muscle. Adiponectin receptor expression is increased by beta cell exposure to the unsaturated FFA oleate, and treatment of insulin-producing cells with globular adiponectin induces lipoprotein lipase expression. Regulated adiponectin receptor expression on pancreatic beta cells might be a novel mechanism modulating the effects of circulating adiponectin.     

Genomic evidence of contemporary hybridization between Schistosoma species

Hybridization between different species of parasites is increasingly being recognised as a major public and veterinary health concern at the interface of infectious diseases biology, evolution, epidemiology and ultimately control. Recent research has revealed that viable hybrids and introgressed lineages between Schistosoma spp. are prevalent across Africa and beyond, including those with zoonotic potential. However, it remains unclear whether these hybrid lineages represent recent hybridization events, suggesting hybridization is ongoing, and/or whether they represent introgressed lineages derived from ancient hybridization events. In human schistosomiasis, investigation is hampered by the inaccessibility of adult-stage worms due to their intravascular location, an issue which can be circumvented by post-mortem of livestock at abattoirs for Schistosoma spp. of known zoonotic potential. To characterise the composition of naturally-occurring schistosome hybrids, we performed whole-genome sequencing of 21 natural livestock infective schistosome isolates. To facilitate this, we also assembled a de novo chromosomal-scale draft assembly of Schistosoma curassoni. Genomic analyses identified isolates of S. bovis, S. curassoni and hybrids between the two species, all of which were early generation hybrids with multiple generations found within the same host. These results show that hybridization is an ongoing process within natural populations with the potential to further challenge elimination efforts against schistosomiasis.     

Nonbiological Conversion of Cephalosporin C to a New Antibiotic by Sodium Thiosulfate

The apparent stimulation of cephalosporin C biosynthesis by sodium thiosulfate is due to a nonbiological conversion of cephalosporin C to a new derivative, cephalosporin C_x. The new compound is more active than cephalosporin C against the assay organism, Escherichia coli W-208. Cephalosporin C_x retains the properties of ultraviolet absorption and resistance to penicillinase, but migrates more slowly than cephalosporin C in the paper-chromatographic system used.     

Isolation,Characterization and Functional Examination of the Gingival Immune Cell Network

Immune cell networks in tissues play a vital role in mediating local immunity and maintaining tissue homeostasis, yet little is known of the resident immune cell populations in the oral mucosa and gingiva. We have established a technique for the isolation and study of immune cells from murine gingival tissues, an area of constant microbial exposure and a vulnerable site to a common inflammatory disease, periodontitis. Our protocol allows for a detailed phenotypic characterization of the immune cell populations resident in the gingiva, even at steady state. Our procedure also yields sufficient cells with high viability for use in functional studies, such as the assessment of cytokine secretion ex vivo. This combination of phenotypic and functional characterization of the gingival immune cell network should aid towards investigating the mechanisms involved in oral immunity and periodontal homeostasis, but will also advance our understanding of the mechanisms involved in local immunopathology.     

Effects of Varied Housing Density on a Hybrid Mouse Strain Followed for 20 Months

To evaluate the effect of increased housing density in a hybrid mouse strain, we evaluated a panel of physiological and behavioral traits in animals that were housed in groups of 3, 5, 8, or 12, using cages that provide 78.1 in² of floor space. Such groupings resulted in cage densities that ranged from half to almost twice the density recommended by the Guide for the Care and Use of Laboratory Animals. While previous studies have investigated physiological effects of increased housing density using inbred mouse strains, including C57BL/6J and 129S1/SvImJ, this study tested an F1 hybrid population of C57BL/6J x 129S1/SvImJ for changes resulting from either decreased or increased housing density. Mice were followed until they were 20 months old, a substantially longer duration than has been used in previous density studies. We evaluated mortality, growth, home cage behavior, blood pressure, body composition, clinical plasma chemistries, immune function, and organ weights (heart, kidney, adrenal glands, and testes) as endpoints of chronic stress that may arise from sub-optimal housing conditions. Few statistically different parameters were observed in this study, none of which describe chronic stress and all within normal physiological ranges for research mice, suggesting that this hybrid strain was not adversely affected by housing at twice the density currently recommended.     

Cytosolic Free Calcium and Gene Expression During Chemical Hypoxia

Understanding the cellular response to hypoxia may help elucidate the role of altered oxidation in neuronal death or abnormal cell function. In PC12 cells, 30 min of chemical hypoxia (i.e., KCN) reduced ATP concentrations by 92%, but diminished viability by only 10%. Ten minutes of hypoxia increased cytosolic free calcium ([Ca2+]i) 2.5-fold above control, but after 30 min of hypoxia, [Ca2+]i was slightly below that of nonhypoxic cells. Short periods of hypoxia also exaggerated the K(+)-induced elevation of [Ca2+]i, but by 30 min these ATP-depleted cells reestablished a calcium gradient that was equal to nonhypoxic, K(+)-depolarized cells. Thus, 30 min of severe ATP depletion left [Ca2+]i and viability relatively unaffected. Nerve growth factor caused slight, but significant, improvements in ATP and viability of hypoxic cells, but had no effect on [Ca2+]i. Although [Ca2+]i was equivalent in control and hypoxic cells after 30 or 60 min, hypoxia abolished the K(+)-stimulated elevation of [Ca2+]i. The nerve growth factor induction of c-fos, an indicator of the genomic response, was diminished by approximately 80%. Thus, hypoxic PC12 cells with greatly reduced ATP stores maintained normal [Ca2+]i, but their ability to respond to external stimulation was impaired. Further, the reduced oxidation that occurs in the brain in a variety of pathological conditions may interfere with the cellular response to stimulation and growth factors.     

Chirality differences in amino acid retention and release from the acid-extractable pool of cultured mammalian cells

In previous work, no chiral differences were found between D and L enantiomers of Leu in their ability to displace one another from the acid-extractable pool in mammalian cells. Recent evidence suggested otherwise. Our aim is to examine whether, in physiological range, D-amino acids have an equivalent ability to displace L-amino acids from the acid-extractable pool of HeLa cells, and vice versa. In the millimolar range, D-Leu and L-Leu have similar uptake and displacement properties with regard to the acid-extractable pool in HeLa cells, despite only the latter isomer being incorporated into protein. Below millimolar concentrations however, a distinct difference was found in the displacement of tritium-labelled L-Leu from the pool by unlabelled D-Leu compared with unlabelled L-Leu. Thus, unlabelled L-Leu in the external medium at 10⁻⁴ or 10⁻⁵ M displaced an equivalent amount of label from the pool as D-Leu introduced at a concentration approx. one order of magnitude higher, respectively. Reciprocal experiments, in which the acid-extractable pool was preloaded with ³H-D-Leu, confirmed this finding. The chirality difference was noted whether pool prelabelling was carried out at 37 or 0°C; but in order to avoid the complications of active transport mechanisms, the competition work reported here was done at 0°C. Similar chirality differences were observed with other hydrophobic amino acids, including His, Ile and Phe, such as, preferential displacement by the L-Leu racemer compared with the D-Leu racemer below mM levels. This was also true for the D and L forms of the non-utilisable isomer of Leu, norleucine (nLeu). We conclude that D-forms of hydrophobic amino acids have lower affinity for similar or the same intracellular binding sites involved in the acid-extractable pool than their L-forms. The significance of these chirality findings to amino acid pools in cells, and to the predominance of L-forms of amino acids in the biosphere is considered.     

Trypanocidal and cytotoxic evaluation of synthesized thiosemicarbazones as potential drug leads against sleeping sickness

Thiosemicarbazones have become one of the promising compounds as new clinical candidates due to their wide spectrum of pharmaceutical activities. The wide range of their biological activities depends generally on their related aldehyde or ketone groups. Here, we report the pharmacological activities of some thiosemicarbazones synthesized in this work. Benzophenone and derivatives were used with N(4)-phenyl-3-thiosemicarbazide to synthesize corresponding five thiosemicarbazones (1–5). Their structures were characterized by spectrometrical methods analysis IR, NMR ¹H & ¹³C and MS. The compounds were then screened in vitro for their antiparasitic activity and toxicity on Trypanosoma brucei brucei and Artemia salina Leach respectively. The selectivity index of each compound was also determined. Four thiosemicarbazones such as 4, 2, 3 and 1 reveal interesting trypanocidal activities with their half inhibitory concentration (IC₅₀) equal to 2.76, 2.83, 3.86 and 8.48 μM respectively, while compound 5 (IC₅₀ = 12.16 μM) showed a moderate anti-trypanosomal activity on parasite. In toxicity test, except compound 1, which showed a half lethal concentration LC₅₀ >281 μM, the others exerted toxic effect on larvae with LC₅₀ of 5.56, 13.62, 14.55 and 42.50 μM respectively for thiosemicarbazones 4, 5, 3 and 2. In agreement to their selectivity index, which is greater than 1 (SI >1), these compounds clearly displayed significant selective pharmaceutical activities on the parasite tested. The thiosemicarbazones 2–5 that displayed significant anti-trypanosomal and cytoxicity activities are suggested to have anti-neoplastic and anti-cancer activities.