Simian crease in man: some methodological considerations

There is no agreement among workers in defining the Simian crease, thus making it difficult to compile or compare their works. The Simian crease, invariably present among anthropoid apes and frequent among mongoloid idiots, is also present in varying degrees among normal populations. Mode of inheritance of this trait is not yet established. This paper attempts to examine critically the definitions and classifications forwarded by various authorities. A new definition has been suggested considering the course of both the distal and the proximal creases. A new classification, to include all transitional variations has also been proposed. A progressive transition from the typical Simian crease to the normal crease configuration is recognized. Further investigation to assess the hereditability of Simian as well as normal creases is emphasized.     

The saponin-rich fraction of a Gymnema sylvestre R. Br. aqueous leaf extract reduces cafeteria and high-fat diet-induced obesity

We examined the antiobesity effect of a saponin-rich fraction of a Gymnema sylvestre R. Br. aqueous leaf extract (SGE) using cafeteria and high-fat diet-induced obese rats for a period of eight weeks. SGE was orally administered at a dose of 100 mg/kg body weight once a day to the treatment group. It significantly decreased the body weight, food consumption, visceral organs weight, and the levels of triglycerides, total cholesterol, low-density lipoproteins, very low-density lipoproteins, atherogenic index, glucose, and increased the levels of high-density lipoproteins. There was no significant difference with respect to all parameters of the study in case of normal (N) diet and N diet + SGE rats. In vitro, SGE inhibited the pancreatic lipase activity. The present study gave clear evidence that the SGE has a significant antiobese action, supporting its use in traditional medicine, and can be used as a substitute for synthetic drugs.     

ParA encoded on chromosome II of Deinococcus radiodurans binds to nucleoid and inhibits cell division in Escherichia coli

Bacterial genome segregation and cell division has been studied mostly in bacteria harbouring single circular chromosome and low-copy plasmids. Deinococcus radiodurans, a radiation-resistant bacterium, harbours multipartite genome system. Chromosome I encodes majority of the functions required for normal growth while other replicons encode mostly the proteins involved in secondary functions. Here, we report the characterization of putative P-loop ATPase (ParA2) encoded on chromosome II of D. radiodurans. Recombinant ParA2 was found to be a DNA-binding ATPase. E. coli cells expressing ParA2 showed cell division inhibition and mislocalization of FtsZ-YFP and those expressing ParA2-CFP showed multiple CFP foci formation on the nucleoid. Although, in trans expression of ParA2 failed to complement SlmA loss per se, it could induce unequal cell division in slmAminCDE double mutant. These results suggested that ParA2 is a nucleoid-binding protein, which could inhibits cell division in E. coli by affecting the correct localization of FtsZ and thereby cytokinesis. Helping slmAminCDE mutant to produce minicells, a phenotype associated with mutations in the ‘Min’ proteins, further indicated the possibility of ParA2 regulating cell division by bringing nucleoid compaction at the vicinity of septum growth.     

Homology and enzymatic requirements of microhomology-dependent alternative end joining

Nonhomologous DNA end joining (NHEJ) is one of the major double-strand break (DSB) repair pathways in higher eukaryotes. Recently, it has been shown that alternative NHEJ (A-NHEJ) occurs in the absence of classical NHEJ and is implicated in chromosomal translocations leading to cancer. In the present study, we have developed a novel biochemical assay system utilizing DSBs flanked by varying lengths of microhomology to study microhomology-mediated alternative end joining (MMEJ). We show that MMEJ can operate in normal cells, when microhomology is present, irrespective of occurrence of robust classical NHEJ. Length of the microhomology determines the efficiency of MMEJ, 5 nt being obligatory. Using this biochemical approach, we show that products obtained are due to MMEJ, which is dependent on MRE11, NBS1, LIGASE III, XRCC1, FEN1 and PARP1. Thus, we define the enzymatic machinery and microhomology requirements of alternative NHEJ using a well-defined biochemical system.DNA double-strand breaks (DSBs) are the most deleterious to the genome among various lesions. Nonhomologous end joining (NHEJ) is one of the major DSB repair pathways in higher eukaryotes.^{1, 2, 3} In the absence of key NHEJ factors, another distinct but error-prone pathway known as alternative NHEJ (A-NHEJ) has been described to have an important role in DSB repair.^{4, 5, 6, 7} It has been shown that majority of A-NHEJ-mediated repair of DSBs utilize distinct microhomology regions, hence termed microhomology-mediated end joining (MMEJ).^{4, 8, 9}A-NHEJ has been proposed as a possible cause for chromosomal translocations. Studies have shown co-amplification of c-MYC and IgH locus from pro-B lymphomas in mice deficient for p53 and NHEJ.¹⁰ A reduced level of class switch recombination (CSR) and increased number of chromosomal rearrangements at IgH locus have been shown in XRCC4- and LIGASE IV-deficient murine B cells.⁸ The occurrence of robust alternative end joining has been reported in the absence of NHEJ proteins, when murine RAG proteins were absent.¹¹Unraveling the enzymatic machinery involved in alternative end joining is currently an active area of research. Recently, it was shown that MRE11-RAD50-NBS1 complex may be involved in a subset of alternative NHEJ,^{5, 12, 13, 14} whereas ATM has a regulatory role.¹⁵ Role of PARP1 in repairing switch regions through a microhomology-mediated pathway leading to IgH/c-MYC translocations during immunoglobulin CSR has been described.¹⁶ Besides, studies have also suggested a role for DNA LIGASE IIIα and WRN in A-NHEJ.¹⁷ Interestingly, XRCC1 was shown to be dispensable in A-NHEJ during CSR, whereas functional relevance of Ligase I, III and Pol λ have been established.^{18, 19, 20} Hence, it can be concluded that canonical NHEJ (C-NHEJ) requires LIGASE IV–XRCC4 complex, while A-NHEJ is predominant in the absence of C-NHEJ proteins and is mainly characterized by joining utilizing microhomology (MMEJ). Further, it has been demonstrated that RPA, when bound to single-stranded DNA can antagonize MMEJ.²¹ Very recently, a genetic system was reported in budding yeast to detect microhomology-mediated repair.²² However, little is known whether alternative NHEJ can be operative when classical NHEJ machinery is intact.²³ A recent study suggested that MMEJ is also functional in normal mammalian cells. Besides, HR and MMEJ share the initial steps of end resection for DSB repair in mammalian cells.²⁴ However, it appears that there is not much consensus among different research groups over its presence and relevance in normal cells.²³ Therefore, several aspects of alternative NHEJ still need to be resolved. For example, its precise mechanism and microhomology length requirements are yet to be fully uncovered. Its occurrence in normal cells needs to be proved beyond doubt. Although there are independent studies showing the role of multiple proteins using gene knockdown or knockout strategies, their involvement needs to be confirmed.In the present study, we have established a cell-free repair assay system using which we show that MMEJ is operative even in the presence of classical NHEJ machinery. Further, our data suggest that MMEJ operates not only in cancer cells but also in normal cells. We show that a minimum of 5 nt microhomology is required for MMEJ and is independent of classical NHEJ proteins such as KU70, KU80 and LIGASE IV. Finally, we show that MRN complex, XRCC1, FEN1, PARP1 and LIGASE III are the factors responsible for joining mediated through microhomology.     

Autoimmune Diabetes Is Suppressed by Treatment with Recombinant Human Tissue Kallikrein-1

The kallikrein-kinin system (KKS) comprises a cascade of proteolytic enzymes and biogenic peptides that regulate several physiological processes. Over-expression of tissue kallikrein-1 and modulation of the KKS shows beneficial effects on insulin sensitivity and other parameters relevant to type 2 diabetes mellitus. However, much less is known about the role of kallikreins, in particular tissue kallikrein-1, in type 1 diabetes mellitus (T1D). We report that chronic administration of recombinant human tissue kallikrein-1 protein (DM199) to non-obese diabetic mice delayed the onset of T1D, attenuated the degree of insulitis, and improved pancreatic beta cell mass in a dose- and treatment frequency-dependent manner. Suppression of the autoimmune reaction against pancreatic beta cells was evidenced by a reduction in the relative numbers of infiltrating cytotoxic lymphocytes and an increase in the relative numbers of regulatory T cells in the pancreas and pancreatic lymph nodes. These effects may be due in part to a DM199 treatment-dependent increase in active TGF-beta1. Treatment with DM199 also resulted in elevated C-peptide levels, elevated glucagon like peptide-1 levels and a reduction in dipeptidyl peptidase-4 activity. Overall, the data suggest that DM199 may have a beneficial effect on T1D by attenuating the autoimmune reaction and improving beta cell health.     

Prostaglandin H Synthetase-Mediated Metabolism of Dopamine: Implication for Parkinson's Disease

Abstract: Differences in prostaglandin H synthetase (PHS) activity in the substantia nigra of age- and post-mortem interval-matched parkinsonian, Alzheimer's, and normal control brain tissue were assessed. Prostaglandin E₂ (PGE₂, an index of PHS activity) was higher in substantia nigra of parkinsonian brain tissue than Alzheimer's or control tissue. Incubation of substantia nigra slices with arachidonic acid (AA) increased PGE₂ synthesis. Dopamine stimulated PHS synthesis of PGE₂. [³H]Dopamine was activated by PHS to electrophilic intermediate(s) that covalently bound to DNA, microtubulin protein, bovine serum albumin, and sulfhydryl reagents. When AA was replaced by hydrogen peroxide, PHS/H₂O₂-supported binding proceeded at rates similar to those observed with PHS/AA. Indomethacin and aspirin inhibited AA-mediated cooxidation of dopamine but not H₂O₂-mediated metabolism. PHS-mediated metabolism of dopamine was not affected by monoamine oxidase inhibitors. Substrate requirements and effects of specific inhibitors suggest cooxidation of dopamine is mediated by the hydroperoxidase activity of PHS. ³²P-postlabeling was used to detect dopamine-DNA adducts. PHS/AA activation of dopamine in the presence of DNA resulted in the formation of five dopamine-DNA adducts, i.e., 23, 43, 114, 70, and 270 amol/µg DNA. DNA adduct formation was PHS, AA, and dopamine dependent. PHS catalyzed cooxidation of dopamine in dopaminergic neuronal degeneration is discussed.