Individualized intensive insulin therapy of diabetes: Not only the goal, but also the time.

Intensive insulin therapy has been extensively used to control blood glucose levels because of its ability to reduce the risk of chronic complications of diabetes. According to current guidelines, intensive glycemic control requires individualized glucose goals rather than as low as possible. During intensive therapy, rapid blood glucose reduction can aggravate microvascular and macrovascular complications, and prolonged overuse of insulin can lead to treatment-induced neuropathy and retinopathy, hypoglycemia, obesity, lipodystrophy, and insulin antibody syndrome. Therefore, we need to develop individualized hypoglycemic plans for patients with diabetes, including the time required for blood glucose normalization and the duration of intensive insulin therapy, which deserves further study.

Cervical cancer cell proliferation inhibition by vanillin oxime through HIF­1α expression inhibition, ERK1/2 and Akt protein down-regulation.

Cervical cancer is a frequently reported cancer of reproductive tract in females and is worldwide 4th most common malignant tumor. The present study investigated the effect of vanillin oxime on proliferation of cervical cancer cells. Vanillin oxime treatment led to suppression of Caski cell proliferation but could not affect proliferation of (HCvEpC) cells at the tested (2 to 10 µM) concentrations. In vanillin oxime treated Caski cells ROS level showed an increase with enhancement in concentration from 2 to 10 µM. Vanillin oxime treatment significantly (P<0.0487) lowered the count of colonies and inhibited invasive abilities of Caski cells. Treatment with vanillin oxime caused a significant (P<0.0487) suppression in HIF­1α expression in Caski cells. Caski cell apoptotic count reached to 8.76% and 48.65%, on incubation with 2 and 10 µM concentrations of vanillin oxime respectively. After treatment with vanillin oxime a prominent reduction in MMP-2 and -9 levels was observed in Caski cells. A prominent reduction in p-ERK1/2 and p-Akt levels was observed in Caski cells after treatment with vanillin oxime. Vanillin oxime inhibits cervical cancer proliferation, invasive abilities, induces apoptotic signalling, and elevates ROS production. Therefore, vanillin oxime may be developed as an effective therapeutic agent for treatment of cervical cancer.

Human Tdp1 cleaves a broad spectrum of substrates, including phosphoamide linkages.

Human tyrosyl-DNA phosphodiesterase (Tdp1) hydrolyzes the phosphodiester bond between a DNA 3' end and a tyrosyl moiety. In eukaryotic cells, this type of linkage is found in stalled topoisomerase I-DNA covalent complexes, and Tdp1 has been implicated in the repair of such complexes in vivo. We confirm here that the Tdp1 catalytic cycle involves a covalent reaction intermediate in which a histidine residue is connected to a DNA 3'-phosphate through a phosphoamide linkage. Most surprisingly, this linkage can be hydrolyzed by Tdp1, and unlike a topoisomerase I-DNA complex, which requires modification to be an efficient substrate for Tdp1, the native form of Tdp1 can be removed from the DNA. The spinocerebellar ataxia with axonal neuropathy neurodegenerative disease is caused by the H493R mutant form of Tdp1, which shows reduced enzymatic activity and accumulates the Tdp1-DNA covalent intermediate. The ability of wild type Tdp1 to remove the stalled mutant protein from the DNA likely explains the recessive nature of spinocerebellar ataxia with axonal neuropathy. In addition to its activity on phosphotyrosine and phosphohistidine substrates, Tdp1 also possesses a limited DNA and RNA 3'-exonuclease activity in which a single nucleoside is removed from the 3'-hydroxyl end of the substrate. Furthermore, Tdp1 also removes a 3' abasic site and an artificial 3'-biotin adduct from the DNA. In combination with earlier data showing that Tdp1 can use 3'-phosphoglycolate as a substrate, these data suggest that Tdp1 may function to remove a variety of 3' adducts from DNA during DNA repair.

SCAN1 mutant Tdp1 accumulates the enzyme--DNA intermediate and causes camptothecin hypersensitivity.

Tyrosyl-DNA phosphodiesterase (Tdp1) catalyzes the hydrolysis of the tyrosyl-3' phosphate linkage found in topoisomerase I-DNA covalent complexes. The inherited disorder, spinocerebellar ataxia with axonal neuropathy (SCAN1), is caused by a H493R mutation in Tdp1. Contrary to earlier proposals that this disease results from a loss-of-function mutation, we show here that this mutation reduces enzyme activity approximately 25-fold and importantly causes the accumulation of the Tdp1-DNA covalent reaction intermediate. Thus, the attempted repair of topoisomerase I-DNA complexes by Tdp1 unexpectedly generates a new protein-DNA complex with an apparent half-life of approximately 13 min that, in addition to the unrepaired topoisomerase I-DNA complex, may interfere with transcription and replication in human cells and contribute to the SCAN1 phenotype. The analysis of Tdp1 mutant cell lines derived from SCAN1 patients reveals that they are hypersensitive to the topoisomerase I-specific anticancer drug camptothecin (CPT), implicating Tdp1 in the repair of CPT-induced topoisomerase I damage in human cells. This finding suggests that inhibitors of Tdp1 could act synergistically with CPT in anticancer therapy.

Expression and purification of immunologically reactive DPPD, a recombinant Mycobacterium tuberculosis skin test antigen, using Mycobacterium smegmatis and Escherichia coli host cells.

DPPD is a Mycobacterium tuberculosis recombinant antigen that elicits specific delayed type hypersensitivity reactions similar in size and morphological aspects to that elicited by purified protein derivative, in both guinea pigs and humans infected with M. tuberculosis. In addition, earlier clinical studies with DPPD suggested that this molecule could improve the specificity of the tuberculin skin test, which is used as an important aid for the diagnosis of tuberculosis. However, these studies could only be performed with DPPD engineered as a fusion molecule with another Mycobacterium spp. protein because no expression of DPPD could be achieved as a single molecule or as a conventional fusion protein in any commercial system. Although recombinant fusion proteins are in general suitable for several biological studies, they are by definition not ideal for studies involving highly purified and defined polypeptide sequences. Here, we report two alternative approaches for the expression of immunologically reactive recombinant genuine DPPD. The first approach used the rapidly growing, nonpathogenic Mycobacterium smegmatis as host cells transformed with the pSMT3 plasmid vector containing the full-length DPPD gene. The second approach used Escherichia coli transformed with the pET-17b plasmid vector containing the DPPD gene engineered in a three-copy fusion manner in tandem with itself. Though at low levels, expression and purification of immunologically reactive DPPD in M. smegmatis could be achieved. More abundant expression and purification of DPPD as a homo-trimer molecule was achieved in E. coli (> or =2 mg/L of bacterial broth cultures). Interestingly, expression could only be achieved in host cells transformed with the DPPD gene containing its leader peptide. However, the expressed proteins lacked the leader sequence, which indicates that processing of the M. tuberculosis DPPD gene was accurately achieved and necessary in both M. smegmatis and E. coli. More importantly, the delayed type hypersensitivity reactions elicited by purified molecules in guinea pigs infected with M. tuberculosis were indistinguishable from that elicited by purified protein derivative. Because the DPPD gene is present only in the tuberculosis-complex organisms of the Mycobacterium genus, these highly purified molecules should be helpful in identifying individuals sensitized with tubercle bacilli.