Dynamic Reassociation of the Nuclear Lamina with Newly Replicated DNA

The physical association of specific regions of chromatin with components of the nuclear lamina provides the framework for the 3-dimensionl architecture of the genome. The regulation of these interactions plays a critical role in the maintenance of gene expression patterns and cell identity. The breakdown and reassembly of the nuclear membrane as cells transit mitosis plays a central role in the regulation of the interactions between the genome and the nuclear lamina. However, other nuclear processes, such as transcription, have emerged as regulators of the association of DNA with the nuclear lamina. To determine whether DNA replication also has the potential to regulate DNA-nuclear lamina interactions, we adapted proximity ligation-based chromatin assembly assays to analyze the dynamics of nuclear lamina association with newly replicated DNA. We observe that lamin A/C and lamin B, as well as inner nuclear membrane proteins LBR and emerin, are found in proximity to newly replicated DNA. While core histones rapidly reassociate with DNA following passage of the replication fork, the complete reassociation of nuclear lamina components with newly replicated DNA occurs over a period of approximately 30 minutes. We propose models to describe the disassembly and reassembly of nascent chromatin with the nuclear lamina.

Histopathologic features predictive of metastasis and survival in 230 patients with cutaneous squamous cell carcinoma of the head and neck and non-head and neck locations: a single-center retrospective study

BACKGROUND

Staging systems for cutaneous squamous cell carcinoma (cSCC) produce inconsistent risk stratification.

OBJECTIVE

The aim of this study was to identify further prognostic parameters for better stratification.

METHODS

We retrospectively analysed the prognostic significance of clinicopathologic parameters of 230 patients who underwent primary excision of invasive cSCC of the head and neck (n = 115) and non-head and non-neck (n = 115) locations. In addition to known high-risk features, we analysed tumour nest shape, invasion pattern, lymphoid response pattern and tumour budding.

RESULTS

On multivariable analysis, lymphovascular invasion (LVI) and high tumour budding predicted worse disease-specific survival, and ulceration, LVI and high tumour budding predicted worse overall survival. Only ulceration was independently associated with risk of nodal metastasis.

CONCLUSION

High tumour budding, LVI and ulceration are independently associated with poor outcome in cSCC and may be used to refine cSCC prognostic stratification, which is crucial to optimize clinical decision and to identify patients who are more likely to benefit from more aggressive interventions or clinical trials.

Comparison of performance indicators of MGIT primary culture to assess the impact of implementation of ISO 15189:2012 standards

Performance indicators are key component and plays a major role for monitoring and continuous quality improvement of the test results. The NABL certificate of accreditation is issued in accordance with the standard ISO 15189:2012 requirements. As part of the accreditation process, the laboratory has acquired knowledge and implemented the quality system procedures. Present study analyzed the impact of the accreditation process on the "performance indicators" of MGIT primary culture and found that performance indicators have been improved significantly after implementation of NABL for almost all indicators which clearly indicate the importance of accreditation and implementation of quality procedures for reliability of valid test results.

Epigenetic regulation of nuclear lamina-associated heterochromatin by HAT1 and the acetylation of newly synthesized histones

A central component of the epigenome is the pattern of histone post-translational modifications that play a critical role in the formation of specific chromatin states. Following DNA replication, nascent chromatin is a 1:1 mixture of parental and newly synthesized histones and the transfer of modification patterns from parental histones to new histones is a fundamental step in epigenetic inheritance. Here we report that loss of HAT1, which acetylates lysines 5 and 12 of newly synthesized histone H4 during replication-coupled chromatin assembly, results in the loss of accessibility of large domains of heterochromatin, termed HAT1-dependent Accessibility Domains (HADs). HADs are mega base-scale domains that comprise ∼10% of the mouse genome. HAT1 globally represses H3 K9 me3 levels and HADs correspond to the regions of the genome that display HAT1-dependent increases in H3 K9me3 peak density. HADs display a high degree of overlap with a subset of Lamin-Associated Domains (LADs). HAT1 is required to maintain nuclear structure and integrity. These results indicate that HAT1 and the acetylation of newly synthesized histones may be critical regulators of the epigenetic inheritance of heterochromatin and suggest a new mechanism for the epigenetic regulation of nuclear lamina-heterochromatin interactions.

Histone acetyltransferase 1 is required for DNA replication fork function and stability

The replisome is a protein complex on the DNA replication fork and functions in a dynamic environment at the intersection of parental and nascent chromatin. Parental nucleosomes are disrupted in front of the replication fork. The daughter DNA duplexes are packaged with an equal amount of parental and newly synthesized histones in the wake of the replication fork through the activity of the replication-coupled chromatin assembly pathway. Histone acetyltransferase 1 (HAT1) is responsible for the cytosolic diacetylation of newly synthesized histone H4 on lysines 5 and 12, which accompanies replication-coupled chromatin assembly. Here, using proximity ligation assay-based chromatin assembly assays and DNA fiber analysis, we analyzed the role of murine HAT1 in replication-coupled chromatin assembly. We demonstrate that HAT1 physically associates with chromatin near DNA replication sites. We found that the association of HAT1 with newly replicated DNA is transient, but can be stabilized by replication fork stalling. The association of HAT1 with nascent chromatin may be functionally relevant, as HAT1 loss decreased replication fork progression and increased replication fork stalling. Moreover, in the absence of HAT1, stalled replication forks were unstable, and newly synthesized DNA became susceptible to MRE11-dependent degradation. These results suggest that HAT1 links replication fork function to the proper processing and assembly of newly synthesized histones.

The flip side of sirtuins: the emerging roles of protein acetyltransferases in aging

Protein N-ε-lysine acetylation is is an important post-translational modification that plays critical roles in the regulation of many cellular processes. A role for this modification in the process of aging goes back two decades to the discovery that the yeast NAD⁺-dependent histone deacetylase Sir2 regulates lifespan in yeast. While the Sirtuin family of protein deacetylases has been intensively studied in many model systems and is definitively linked to aging, the enzymes responsible for protein acetylation, protein acetyltransferases (KATs), have not received a similar level of attention. However, a series of recent studies have directly explored the role of specific KATs in aging. These studies have shown that modulation of KAT activity can influence cellular pathways important for aging and directly effect organismal lifespan.

Hat1-Dependent Lysine Acetylation Targets Diverse Cellular Functions

Lysine acetylation has emerged as one of the most important post-translational modifications, regulating different biological processes. However, its regulation by lysine acetyltransferases is still unclear in most cases. Hat1 is a lysine acetyltransferase originally identified based on its ability to acetylate histones. Using an unbiased proteomics approach, we have determined how loss of Hat1 affects the mammalian acetylome. Hat1^+/+ and Hat1^-/- mouse embryonic fibroblast cell lines were grown in both glucose- and galactose-containing media, as Hat1 is required for growth on galactose, and Hat1^-/- cells exhibit defects in mitochondrial function. Following trypsin digestion of whole cell extracts, acetylated peptides were enriched by acetyllysine affinity purification, and acetylated peptides were identified and analyzed by label-free quantitation. Comparison of the acetylome from Hat1^+/+ cells grown on galactose and glucose demonstrated that there are large carbon source-dependent changes in the mammalian acetylome where the acetylation of enzymes involved in glycolysis were the most affected. Comparisons of the acetylomes from Hat1^+/+ and Hat1^-/- cells identified 65 proteins whose acetylation decreased by at least 2.5-fold in cells lacking Hat1. In Hat1^-/- cells, acetylation of the autoregulatory loop of CBP (CREB-binding protein) was the most highly affected, decreasing by up to 20-fold. In addition to the proteins involved in chromatin structure, Hat1-dependent acetylation was also found in a number of transcriptional regulators, including p53 and mitochondrial proteins. Hat1 mitochondrial localization suggests that it may be directly involved in the acetylation of mitochondrial proteins. Data are available via ProteomeXchange with identifier PXD017362.

Early-onset aging and mitochondrial defects associated with loss of histone acetyltransferase 1 (Hat1)

Histone acetyltransferase 1 (Hat1) is responsible for the acetylation of newly synthesized histone H4 on lysines 5 and 12 during the process of chromatin assembly. To understand the broader biological role of Hat1, we have generated a conditional mouse knockout model of this enzyme. We previously reported that Hat1 is required for viability and important for mammalian development and genome stability. In this study, we show that haploinsufficiency of Hat1 results in a significant decrease in lifespan. Defects observed in Hat1^+/− mice are consistent with an early‐onset aging phenotype. These include lordokyphosis (hunchback), muscle atrophy, minor growth retardation, reduced subcutaneous fat, cancer, and paralysis. In addition, the expression of Hat1 is linked to the normal aging process as Hat1 mRNA and protein becomes undetectable in many tissues in old mice. At the cellular level, fibroblasts from Hat1 haploinsufficient embryos undergo early senescence and accumulate high levels of p21. Hat1^+/− mouse embryonic fibroblasts (MEFs) display modest increases in endogenous DNA damage but have significantly higher levels of reactive oxygen species (ROS). Consistently, further studies show that Hat1^−/− MEFs exhibit mitochondrial defects suggesting a critical role for Hat1 in mitochondrial function. Taken together, these data show that loss of Hat1 induces multiple hallmarks of early‐onset aging.

An unusual case of unresolving tunnel infection in a patient on continuous ambulatory peritoneal dialysis

Atypical mycobacteria remain a rare cause of peritoneal dialysis catheter-related tunnel infection (TI) and poses serious risk because of the resistant nature to most antibiotic therapy. Non-tubercular mycobacterial infections lead to chronicity requiring peritoneal dialysis catheter removal. We report an 82-year-old male, with diabetic nephropathy who had a coinfection with Staphylococcus hominis and Mycobacterium abscessus who presented with pus discharge at exit site and TI. He was treated with relocation of the extraperitoneal part of the catheter with a new exit site without catheter removal and multidrug mycobacterial therapy.

Spitzoid melanoma with histopathological features of ALK gene rearrangement exhibiting ALK copy number gain: a novel mechanism of ALK activation in spitzoid neoplasia

Spitzoid neoplasms pose diagnostic difficulties because their morphology is not consistently predictive of their biological potential. Recent advances in the molecular characterization of these tumours provides a framework by which they can now begin to be categorized. In particular, spitzoid lesions with ALK rearrangement have been specifically associated with a characteristic plexiform growth pattern of intersecting fascicles of amelanotic spindled melanocytes. We report the case of an 87-year-old man with a 3-cm nodule on his mid-upper back comprised of an intradermal proliferation of fusiform amelanotic melanocytes arranged in intersecting fascicles with occasional peritumoral clefts. Immunohistochemical studies demonstrated diffuse, strong expression of SOX10 and S100 by the tumour cells and diffuse, weak-to-moderate cytoplasmic positivity for anaplastic lymphoma kinase (ALK), suggestive of ALK rearrangement. Fluorescence in situ hybridization revealed no ALK rearrangements but instead revealed at least three intact ALK signals in 36% of the tumour cells, confirming ALK copy number gain. To our knowledge, this is the first reported case of a plexiform spitzoid neoplasm exhibiting ALK copy number gain instead of ALK rearrangement. This case suggests that ALK copy number gain is a novel mechanism of ALK activation but with the same characteristic histopathological growth pattern seen among ALK-rearranged spitzoid neoplasms.

Pruritic arthropod bite-like papules in T-cell large granular lymphocytic leukaemia and chronic myelomonocytic leukaemia

T-cell large granular lymphocytic leukaemia (T-LGLL) is a clinically indolent mature T-cell neoplasm characterized by a monoclonal population of CD3+ CD8+ cytotoxic T cells, which usually presents as neutropenia, anaemia and thrombocytopenia. Chronic myelomonocytic leukaemia (CMML) is a clonal haematopoietic disorder with features of both a myeloproliferative neoplasm and myelodysplastic syndrome (MDS). Patients with CMML exhibit a persistent peripheral blood monocytosis in addition to myelodysplastic features. Because of the rarity of T-LGLL, its cutaneous manifestations are poorly documented, but include vasculitis, vasculopathy, persistent ulcerations, generalized pruritus and disseminated granuloma annulare. Various types of skin lesions have been observed in patients with CMML and reportedly occur in approximately 10% of cases. We report the extraordinary case of a patient with MDS who developed T-LGLL, and subsequently the MDS progressed to CMML. The patient then developed diffuse arthropod bite-like papules and intractable pruritus.

Identification of multiple roles for histone acetyltransferase 1 in replication-coupled chromatin assembly

Histone acetyltransferase 1 (Hat1) catalyzes the acetylation of newly synthesized histone H4 at lysines 5 and 12 that accompanies replication-coupled chromatin assembly. The acetylation of newly synthesized H4 occurs in the cytoplasm and the function of this acetylation is typically ascribed to roles in either histone nuclear import or deposition. Using cell lines from Hat1^+/+ and Hat1^−/− mouse embryos, we demonstrate that Hat1 is not required for either histone nuclear import or deposition. We employed quantitative proteomics to characterize Hat1-dependent changes in the composition of nascent chromatin structure. Among the proteins depleted from nascent chromatin isolated from Hat1^−/− cells are several bromodomain-containing proteins, including Brg1, Baz1A and Brd3. Analysis of the binding specificity of their bromodomains suggests that Hat1-dependent acetylation of H4 is directly involved in their recruitment. Hat1^−/− nascent chromatin is enriched for topoisomerase 2α and 2β. The enrichment of topoisomerase 2 is functionally relevant as Hat1^−/− cells are hyper-sensitive to topoisomerase 2 inhibition suggesting that Hat1 is required for proper chromatin topology. In addition, our results indicate that Hat1 is transiently recruited to sites of chromatin assembly, dissociating prior to the maturation of chromatin structure.

Variants of katG, inhA and nat genes are not associated with mutations in efflux pump genes (mmpL3 and mmpL7) in isoniazid-resistant clinical isolates of Mycobacterium tuberculosis from India

To understand the impact of efflux pump genes such as mmpL3 and mmpL7 on isoniazid (INH) resistance and to correlate with presence or absence of mutations in essential genes of INH resistance (katG, inhA, and nat) in clinical isolates of Mycobacterium tuberculosis (M. tuberculosis). One hundred (75 resistant and 25 sensitive) clinical isolates of M. tuberculosis from India were selected for the study. The presence of mutations in specific regions of katG, inhA, and nat, efflux pump genes (mmpL3 and mmpL7) associated with INH resistance were analyzed using multiplex allele-specific polymerase chain reaction (MAS-PCR) and DNA sequencing methods, respectively. Substitution mutation AGC-ACC at codon 315 of the katG gene was detected in 65% of resistant isolates. Mutation (C-T at nucleotide position 15) in the inhA promoter region was seen in 22% of resistant isolates. Silent mutation (GGA to GGG) at codon 207 in the nat gene was found in three resistant isolates. No mutations were found in either of the efflux genes (mmpL3 and mmpL7) in any of the isolates. Of the 75 resistant isolates analyzed, 74% had mutation in katG and inhA genes. Thus, this report suggests that the role of mmpL3, mmpL7 and nat genes in INH resistance should not be overestimated in comparison to the primary contribution by katG and inhA in clinical isolates of M. tuberculosis. Further, this concise report is the first of its kind to our knowledge, to show the influence of efflux genes on INH resistance in relation to katG and inhA in clinical isolates of M. tuberculosis.

Efficacy of Onalespib, a Long-Acting Second-Generation HSP90 Inhibitor, as a Single Agent and in Combination with Temozolomide against Malignant Gliomas

Purpose: HSP90, a highly conserved molecular chaperone that regulates the function of several oncogenic client proteins, is altered in glioblastoma. However, HSP90 inhibitors currently in clinical trials are short-acting, have unacceptable toxicities, or are unable to cross the blood-brain barrier (BBB). We examined the efficacy of onalespib, a potent, long-acting novel HSP90 inhibitor as a single agent and in combination with temozolomide (TMZ) against gliomas in vitro and in vivoExperimental Design: The effect of onalespib on HSP90, its client proteins, and on the biology of glioma cell lines and patient-derived glioma-initiating cells (GSC) was determined. Brain and plasma pharmacokinetics of onalespib and its ability to inhibit HSP90 in vivo were assessed in non-tumor-bearing mice. Its efficacy as a single agent or in combination with TMZ was assessed in vitro and in vivo using zebrafish and patient-derived GSC xenograft mouse glioma models.Results: Onalespib-mediated HSP90 inhibition depleted several survival-promoting client proteins such as EGFR, EGFRvIII, and AKT, disrupted their downstream signaling, and decreased the proliferation, migration, angiogenesis, and survival of glioma cell lines and GSCs. Onalespib effectively crossed the BBB to inhibit HSP90 in vivo and extended survival as a single agent in zebrafish xenografts and in combination with TMZ in both zebrafish and GSC mouse xenografts.Conclusions: Our results demonstrate the long-acting effects of onalespib against gliomas in vitro and in vivo, which combined with its ability to cross the BBB support its development as a potential therapeutic agent in combination with TMZ against gliomas. Clin Cancer Res; 23(20); 6215-26. ©2017 AACR.

Abstract 683: DEBIO0932, an Hsp90 inhibitor downregulates key signaling pathways and sensitizes glioma cells to temozolomide

Heat shock protein 90 (Hsp90), a molecular chaperone that regulates proper folding, stabilization and degradation of key regulatory client proteins, has also been implicated in maintenance of high levels of aberrantly expressed proteins such as kinases and transcription factors in several malignancies. Hence Hsp90 inhibition has emerged as a novel strategy for therapeutic targeting of cancers. Several Hsp90 inhibitors (Hsp90i) have demonstrated efficacy as anti-neoplastic agents in pre-clinical studies by inducing downregulation of key oncogenic proteins such as Akt, EGFR, ErKs, STAT3 and VEGFR resulting in differentiation or death of malignant cells. DEBIO0932 is an orally bioavailable second generation HSP90i which can cross the blood brain barrier (BBB) and has shown preclinical efficacy both as a single agent and in combination therapy against several malignancies. However, its possible efficacy in gliomas has not been fully characterized. We examined the effects of DEBIO0932 as a single agent and in combination with temozolomide (TMZ) using glioma cell lines (U373, LN229, U251HF) and glioma stem-like cells (GSC11, GSC23). DEBIO0932-treated glioma cells and GSC showed decreased proliferation in a WST-1 assay and induction of apoptosis by flow cytometry. Western blot analysis of DEBIO0932 treated cells showed activation of apoptotic pathways and downregulation of EGFR, Akt and MAPK which are key regulators of survival pathways and drivers of malignancy in glioblastoma. Wound healing and migration assay showed reduced Glioma cell motility, decreased migration and invasion after DEBIO0932 treatment. Analysis of effects of DEBIO0932 on key signaling molecules using a kinase array showed downregulation of several key kinases relevant to glioma biology; of particular interest, treatment with DEBIO0932 caused downregulation of β-catenin which has been implicated in maintenance of tumor stem cell state. Corresponding to this, we also observed downregulation of CD133, a marker enriched in glioma stem cells. Additionally, given the downregulation of several proteins implicated in cell survival and treatment resistance, we tested the ability of DEBIO0932 to increase the cytotoxic effect of temozolomide (TMZ) in glioma cells. Combination studies showed a synergistic effect of DEBIO0932 and TMZ against gliomas cells and GSC indicating the potential for Hsp90i in overcoming tumor cell resistance to cytotoxic signals. Our results strongly support the potential for Hsp90 inhibition as a therapeutic strategy against gliomas particularly in combination with cytotoxic agents such as TMZ. The oral bioavailability and ability to cross the BBB make DEBIO0932 a promising agent for therapeutic targeting of glioblastoma.

Citation Format: Alessandro Canella, Jihong Xu, W. Hans Meisen, Balveen Kaur, Lara Rizzotto, Divya Kesanakurti, Prabakaran Nagarajan, Vinay K. Puduvalli. DEBIO0932, an Hsp90 inhibitor downregulates key signaling pathways and sensitizes glioma cells to temozolomide. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 683. doi:10.1158/1538-7445.AM2015-683

Mineral bone disease in maintenance hemodialysis patients: Association with morbidity and mortality

There is a paucity of data on mineral bone disease in maintenance hemodialysis (MHD) patients from India. This retrospective analysis was undertaken on 858 (males: 599; females: 259) patients from two medical centers on MHD from 1998 to 2010. Age, gender, months on dialysis, hours per session of dialysis, hemoglobin, serum calcium, inorganic phosphorus, intact parathyroid hormone (iPTH), urine output, erythropoietin dosage per week, blood sugar, blood pressure, urea reduction rate, gain in fluid and fluid removed per session, serum albumin, alkaline phosphatase, vitamin D level, supplemental vitamin D and use of phosphate binder for therapy were documented. Overall, 191 patients died (22%) during the observation period. There was an 86% patient survival rate at 1 year on dialysis and an overall predicted 3-year survival rate of 78%. A relatively higher iPTH (P = 0.012), a need for vitamin D supplementation (P = 0.003), less hours on dialysis per session (P = 0.046) and a non-vegetarian diet (P = 0.022) were significantly associated with mortality.

Rare occurrence of fatal Candida haemulonii peritonitis in a diabetic CAPD patient

A 68-year-old diabetic chronic kidney disease patient on continuous ambulatory peritoneal dialysis for two years developed Candida haemulonii peritonitis without any predisposing factors. There is no effective treatment for this fungus. A peritoneal biopsy showed morphological changes of acute inflammation and chronicity.

A non-surgical approach for male germ cell mediated gene transmission through transgenesis

Microinjection of foreign DNA in male pronucleus by in-vitro embryo manipulation is difficult but remains the method of choice for generating transgenic animals. Other procedures, including retroviral and embryonic stem cell mediated transgenesis are equally complicated and have limitations. Although our previously reported technique of testicular transgenesis circumvented several limitations, it involved many steps, including surgery and hemicastration, which carried risk of infection and impotency. We improved this technique further, into a two step non-surgical electroporation procedure, for making transgenic mice. In this approach, transgene was delivered inside both testes by injection and modified parameters of electroporation were used for in-vivo gene integration in germ cells. Using variety of constructs, germ cell integration of the gene and its transmission in progeny was confirmed by PCR, slot blot and immunohistochemical analysis. This improved technique is efficient, requires substantially less time and can be easily adopted by various biomedical researchers.

Increasing the complexity of chromatin: functionally distinct roles for replication-dependent histone H2A isoforms in cell proliferation and carcinogenesis

Replication-dependent histones are encoded by multigene families found in several large clusters in the human genome and are thought to be functionally redundant. However, the abundance of specific replication-dependent isoforms of histone H2A is altered in patients with chronic lymphocytic leukemia. Similar changes in the abundance of H2A isoforms are also associated with the proliferation and tumorigenicity of bladder cancer cells. To determine whether these H2A isoforms can perform distinct functions, expression of several H2A isoforms was reduced by siRNA knockdown. Reduced expression of the HIST1H2AC locus leads to increased rates of cell proliferation and tumorigenicity. We also observe that regulation of replication-dependent histone H2A expression can occur on a gene-specific level. Specific replication-dependent histone H2A genes are either up- or downregulated in chronic lymphocytic leukemia tumor tissue samples. In addition, discreet elements are identified in the 5′ untranslated region of the HIST1H2AC locus that confer translational repression. Taken together, these results indicate that replication-dependent histone isoforms can possess distinct cellular functions and that regulation of these isoforms may play a role in carcinogenesis.

Effect of long-term castration on serum biochemistry in rhesus monkeys

BACKGROUND

Testicular failure has an effect on normal physiology. To address this issue, an experimental non-human primate model of long-term castrated rhesus monkey was chosen for this study to evaluate the influence of castration on various biochemical parameters.

METHODS

Nine castrated rhesus monkeys were evaluated for changes in body weight, serum testosterone, and serum biochemical parameters as compared to those in non-castrated macaques.

RESULTS

Castration caused statistically significant changes in body weight, biochemical analytes, and testosterone levels. Body weight and testosterone levels were decreased, and there were increase in alanine aminotransferase, cholesterol, serum bilirubin, phosphorous, alkaline phosphatase, urea and a decrease in serum protein, uric acid, creatinine, and triglycerides.

CONCLUSIONS

This study provided essential baseline information on biochemical variables due to the effect of castration associated with declining levels of testosterone, as data are not readily accessible from the existing body of scientific literature on non-human primates.

Constant Temperature Microfeature Embossing with Slowly Crystallizing Polymers

A new microfeature embossing method utilizing a slowly crystallizing mechanism was investigated to eliminate thermal cycling, as needed in standard hot embossing. Poly(ethylene terephthalate) was used as a model system for demonstration. Due to its slow crystallization, amorphous PET film can be made by melt casting onto a chilled roll. The resulting amorphous film was embossed at a constant temperature of 180°C for a period of time comparable to or longer than the polymer's half-time of crystallization. During constant-temperature embossing, the film is softened first, caused by rubber softening of the amorphous phase, and is then hardened, resulting from the crystallization of the amorphous phase at the same embossing temperature. Since the embossed film is hardened under the constant mold temperature, no cooling is needed. Selected micro features, including circular microchannels and high aspect ratio microribs, were consistently patterned using a total cycle time about 40s. The embossed films were characterized using DSC and rotational rheometry to elucidate the physical mechanism for softening and hardening the polymer during constant-temperature embossing.

Retrieval of Mycobacterium tuberculosis cultures suspended in phosphate buffered saline

One hundred and twenty-seven of 130 isolates of Mycobacterium tuberculosis, suspended in phosphate buffered saline (PBS) and stored at ambient conditions in the laboratory for 14days, and another 55 of 60 cultures, suspended as above, transported from reference laboratories within 7days, were successfully retrieved on LJ medium. Considering the maximum retrieval of M. tuberculosis, use of PBS can be explored further for transportation of M. tuberculosis cultures across laboratories.

Protocol for long duration whole body hyperthermia in mice

Hyperthermia is a general term used to define the increase in core body temperature above normal. It is often used to describe the increased core body temperature that is observed during fever. The use of hyperthermia as an adjuvant has emerged as a promising procedure for tumor regression in the field of cancer biology. For this purpose, the most important requirement is to have reliable and uniform heating protocols. We have developed a protocol for hyperthermia (whole body) in mice. In this protocol, animals are exposed to cycles of hyperthermia for 90 min followed by a rest period of 15 min. During this period mice have easy access to food and water. High body temperature spikes in the mice during first few hyperthermia exposure cycles are prevented by immobilizing the animal. Additionally, normal saline is administered in first few cycles to minimize the effects of dehydration. This protocol can simulate fever like conditions in mice up to 12-24 hr. We have used 8-12 weeks old BALB/Cj female mice to demonstrate the protocol.

Assessment of panel slides prepared by phenol ammonium sulphate and NALC methods for proficiency testing

BACKGROUND

Existing methods for the preparation of panel slides necessitate handling high-grade acid-fast bacilli positive sputum samples.

OBJECTIVE

To compare panel slides prepared using the phenol ammonium sulphate sediment (PhAS) method with those prepared using the N-acetyl-L-cysteine (NALC) method in proficiency testing.

METHODS

Pooled sputum specimens of known smear-positives and -negatives were divided into two parts: one part was used for preparing panel slides using the NALC method and the other using PhAS, a non-hazardous method. Respectively 413 and 384 smears of different grades were prepared in three batches using the PhAS and NALC methods. Smear grade and quality were recorded by 121 microscopists during proficiency testing in different states. Agreement between reference and reported results was analysed using the kappa test.

RESULTS

The overall agreement was 96% for the PhAS method and 91% for the NALC method. There were 37 errors using the NALC method compared to 21 for the PhAS method (P < 0.223). Smear quality was equally good in both methods; however, the cell count was significantly higher in the PhAS than in the NALC method.

CONCLUSION

The PhAS method, a non-hazardous procedure with good-quality smears, may be further explored for the preparation of panel slides.

Recovery of Mycobacterium tuberculosis from Löwenstein-Jensen media contaminated with other organisms

Growth of contaminating organisms along with Mycobacterium tuberculosis on Löwenstein-Jensen (LJ) medium is common. However, there is no documented evidence on the decontamination procedure adopted in mycobacteriology laboratories to recover M. tuberculosis from the contaminants grown on LJ medium. At the National Institute for Research in Tuberculosis, of 1048 LJ slopes with M. tuberculosis received from intermediate reference laboratories, 98 (9%) were contaminated. Of these, 87 (89%) M. tuberculosis cultures were retrieved after decontamination with 1% cetrimide. The use of cetrimide as a decontaminating agent to retrieve M. tuberculosis cultures grown with contaminants is documented.

Effect of dietary β carotene on cerebral aneurysm and subarachnoid haemorrhage in the brain apo E-/- mice

Atherosclerosis will lead to stenosis/occlusion in the lumen of various arteries of living body. This can lead various conditions including myocardial infarction, cerebral infarction/aneurysm and peripheral artery disease. Ang II is believed to be an important regulatory peptide involved in maintaining cardiovascular homeostasis and pathogenesis of various cardiovascular diseases. Matrix metalloproteinase's (MMPs), adhesion molecules and plasminogen systems are involved in the inflammatory reaction of various blood vessels as well as pathogenesis of cerebro vasuclar disease in apo E(-/-) mice during angiotensin II injection. The present study analyses the role of ang II in development of cerebral aneurysm and also evaluated the mRNA levels of MMPs, adhesion molecules, plasminogen systems and peroxisome proliferators-associated receptors in the brain of apo E(-/-) mouse during the progression of cerebral aneurysm and ischemic conditions. Also, this study evaluates the role of dietary β carotene on cerebrovascular disease. Serum total cholesterol (TC), Low density lipoprotein (LDL) and triglyceride (TG) levels were significantly increased in angiotensin II treated animals and further β carotene supplementation reduces TC but does not affect the triglyceride and LDL levels. Circulating levels of macrophages were significantly increased in angiotensin treated animals and further beta carotene supplementation significantly reduced the circulating macrophages. Cerebro meningeous aneurysm, subarachnoid haemorrhage, multiple foci of infarction, necrosis and infiltration of inflammatory cells were observed in the cerebral hemispheres of ang II treated animals, however, infarction size were reduced and no aneurysm, inflammatory foci was observed in β carotene treated animals. Real time analysis showed down regulation of mRNA levels of MMP 2, uPA, PAI, PPAR-A, MCSF1 and up regulation of tPA and MCP-1 in the brain during the progression of cerebral aneurysm and β carotene supplementation to bring to normal expression levels of all the candidate genes for cerebrovascular diseases. Based on above results, Ang II may induced cerebral aneurysm, ischemia/infarction on brain through RAS system by down regulating the mRNA levels of MMP 2, uPA, PAI, PPAR-A, MCSF1 and up regulating tPA and MCP-1 and β carotene attenuates the disease condition and bring down to normal expression levels of above genes.

Potassium channel opening: a subtle two-step

Voltage-gated K(+) channels undergo a voltage-dependent conductance change that plays a key role in modulating cellular excitability. While the Open state is captured in crystal structures of Kv1.2 and a chimeric Kv1.2/Kv2.1 channel, the Close state and the mechanism of this transition are still a subject of debate. Here, we propose a model based on mutagenesis combined with measurements of both ionic and gating currents which is consistent with the idea that the Open state is the default state, the energy of the electric field being used to keep the channel closed. Our model incorporates an 'Activated state' where the bulk of sensor movement is completed without channel opening. The model accounts for the well characterized electrophysiology of the 'V2' and 'ILT' mutations in Shaker, where sensor movement and channel opening occur over distinct voltage ranges. Moreover, the model proposes relatively small protein rearrangements in going from the Activated to the Open state, consistent with the rapid transitions observed in single channel records of Shaker type channels at zero millivolts.

Role of chromodomain helicase DNA-binding protein 2 in DNA damage response signaling and tumorigenesis

The chromodomain helicase DNA-binding proteins (CHDs) are known to affect transcription through their ability to remodel chromatin and modulate histone deacetylation. In an effort to understand the functional role of the CHD2 in mammals, we have generated a Chd2 mutant mouse model. Remarkably, the Chd2 protein appears to play a critical role in the development, hematopoiesis and tumor suppression. The Chd2 heterozygous mutant mice exhibit increased extramedullary hematopoiesis and susceptibility to lymphomas. At the cellular level, Chd2 mutants are defective in hematopoietic stem cell differentiation, accumulate higher levels of the chromatin-associated DNA damage response mediator, gamma H2AX, and exhibit an aberrant DNA damage response after X-ray irradiation. Our data suggest a direct role for the chromatin remodeling protein in DNA damage signaling and genome stability maintenance.

Disruption of chromodomain helicase DNA binding protein 2 (CHD2) causes scoliosis

Herein we characterize an apparently balanced de novo translocation, t(X;15)(p22.2;q26.1)dn, in a female patient with scoliosis, hirsutism, learning problems, and developmental delay (DGAP025). Other clinical findings include a high-arched palate, 2-3 syndactyly of the toes, and mildly elevated serum testosterone. No known or predicted genes are disrupted by the Xp22.2 breakpoint. The 15q26.1 breakpoint disrupts chromodomain helicase DNA binding protein 2 (CHD2). Another member of the chromatin-remodeling gene family, CHD7, has been associated with a defined constellation of congenital anomalies known as coloboma, heart anomaly, choanal atresia, mental retardation, genital and ear anomalies syndrome (CHARGE) and idiopathic scoliosis. Monosomy of 15q26 also has been associated with a spectrum of congenital abnormalities and growth retardation that overlaps with those of DGAP025. To provide a biological correlate, we characterized a mutant mouse model with Chd2 disruption that is associated with embryonic and perinatal lethality. Expression analysis indicated that Chd2 is expressed in the heart, forebrain, extremities, facial and dorsal regions during specific times of embryonic development. Chd2(+/m) mice showed pronounced lordokyphosis, reduced body fat, postnatal runting, and growth retardation. These data suggest that haploinsufficiency for CHD2 could result in a complex of abnormal human phenotypes that includes scoliosis and possibly features similar to CHARGE syndrome.