DNase I site mapping and micrococcal nuclease digestion of pachytene chromatin reveal novel structural features

A comparison of the DNase I digestion products of the 32P-5'-end-labeled pachytene nucleosome core particles (containing histones H2A, TH2A, X2, H2B, TH2B, H3, and H4) and liver nucleosome core particles (containing somatic histones H2A, H2B, H3, and H4) revealed that the cleavage sites that are 30, 40, and 110 nucleotides away from the 5'-end are significantly more accessible in the pachytene core particles than in the liver core particles. These cleavage sites correspond to the region wherein H2B interacts with the nucleosome core DNA. These results, therefore, suggest that the histone-DNA interaction at these sites in the pachytene core particles is weaker, possibly because of the presence of the histone variant TH2B interacting at similar topological positions in the nucleosome core as that of its somatic counterpart H2B. Such a loosened structure may also be maintained even in the native pachytene chromatin since micrococcal nuclease digestion of pachytene nuclei resulted in a higher ratio of subnucleosomes (SN4 + SN7) to mononucleosomes than that observed in liver chromatin

Demographics and Histopathological Patterns of Oral Squamous Cell Carcinoma at a Tertiary Level Referral Hospital in Hyderabad, India: A 5-Year Retrospective Study

Background: To study the demographics and histopathological patterns of oral squamous cell carcinoma (OSCC) reported at a tertiary level referral teaching hospital in Hyderabad, India. Materials and methods: An institutional retrospective study of biopsies sent to a tertiary level referral teaching hospital, Hyderabad. The data was collected year-wise for a period of 5 years from 2007 to 2011 with reference to age, sex, site involved and final diagnosis based on the histopathological findings. Results: A total of 1,005 oral biopsies were reviewed. Of these, OSCC was seen in 234 cases (23.28%). Buccal mucosa (47.7%) was the most frequently involved site followed by tongue (27.6%). Most of the OSCC patients were in the age group of 41 to 50 years, males and histopathologically well-differentiated (62%). Conclusion: This study showed that OSCC is widespread in the patients of this region

DNase I Site Mapping and Micrococcal Nuclease Digestion of Pachytene Chromatin Reveal Novel Structural Features

A comparison of the DNase I digestion products of the 32P-5’-end-labeled pachytene nucleosome core particles (containing histones H2A, TH2A, X2, H2B, THPB, H3a, nd H4) and liver nucleosome core particles (containing somatic histones H2A, H2B, H3, and H4) revealed that the cleavage sites that are 30, 40, and 110 nucleotidesa way from the 5’-enda re significantly more accessiblei n the pachytene core particles than in the liver core particles. These cleavage sites correspond to the region wherein H2B interacts with the nucleosome core DNA. These results, therefore, suggest that the histone-DNA interactiona t these sites in the pachytene core particles is weaker, possibly because of the presence of the histone variant THBB interacting at similar topological positions in the nucleosome core as that of its somatic counterpart H2B. Such a loosened structumrea y also be maintainede ven in the native pachytene chromatin since micrococcal nuclease digestion of pachytene nuclei resulted in a higher ratio of subnucleosomes (SN4 + SN?) to mononucleosomes than that observed liinv er chromati

RecA protein reinitiates strand exchange on isolated protein-free DNA intermediates. An ADP-resistant process

Efficient homologous pairing de novo of linear duplex DNA with a circular single strand (plus strand) coated with RecA protein requires saturation and extension of the single strand by the protein. However, strand exchange, the transfer of a strand from duplex DNA to the nucleoprotein filament, which follows homologous pairing, does not require the stable binding of RecA protein to single-stranded DNA. When RecA protein was added back to isolated protein-free DNA intermediates in the presence of sufficient ADP to inhibit strongly the binding of RecA protein to single-stranded DNA, strand exchange nonetheless resumed at the original rate and went to completion. Characterization of the protein-free DNA intermediate suggested that it has a special site or region to which RecA protein binds. Part of the nascent displaced plus strand of the deproteinized intermediate was unavailable as a cofactor for the ATPase activity of RecA protein, and about 30% resisted digestion by P1 endonuclease, which acts preferentially on single-stranded DNA. At the completion of strand exchange, when the distal 5′ end of the linear minus strand had been fully incorporated into heteroduplex DNA, a nucleoprotein complex remained that contained all three strands of DNA from which the nascent displaced strand dissociated only over the next 50 to 60 minutes. Deproteinization of this intermediate yielded a complex that also contained three strands of DNA in which the nascent displaced strand was partially resistant to both Escherichia coli exonuclease I and P1 endonuclease. The deproteinized complex showed a broad melting transition between 37°C and temperatures high enough to melt duplex DNA. These results show that strand exchange can be subdivided into two stages: (1) the exchange of base-pairs, which creates a new heteroduplex pair in place of a parental pair; and (2) strand separation, which is the physical displacement of the unpaired strand from the nucleoprotein filament. Between the creation of new heteroduplex DNA and the eventual separation of a third strand, there exists an unusual DNA intermediate that may contain three-stranded regions of natural DNA that are several thousand bases in length

Knowledge, attitude and practices related to oral health among English and Telugu medium school teachers in two districts of Andhra Pradesh, India: A comparative study

Background: A teacher with adequate oral health knowledge, positive attitude toward dental health can always play an important role in health education of school children and be a role model for children, lay people and the community at large. Objective: To assess and compare the oral health knowledge among English and Telugu medium primary school teachers in Hyderabad and Ranga Reddy districts of Andhra Pradesh. Materials and Methods: A cross-sectional questionnaire study was conducted among 300 primary school teachers selected from two districts of Andhra Pradesh. A combination of cluster and systematic random sampling technique was employed for the selection of study participants. The data on oral health knowledge, attitude and practices (KAP) were collected by two investigators using a structured questionnaire. The data were entered onto a personal computer, and statistical analysis was done using SPSS version 20. Results: A total of 150 school teachers each from English (62 males and 88 females) and Telugu medium (62 males and 88 females) schools participated in the study. By considering the oral hygiene aid used and frequency of brushing, it was evident that the oral hygiene practices were better among English medium teachers compared to their counterparts in Telugu medium. The teachers in English medium had favorable attitudes toward dental health than teachers in Telugu medium. Conclusion: The study found English medium teachers to be having better oral hygiene practices, more frequent dental visits, and better awareness about first aid in dentistry. However, the lack of preventive attitude, lack of motivation to be role models for children in oral health maintenance, reflect that there is a tremendous need to improve the oral health KAP among schoo teachers

Demographics and histopathological patterns of oral squamous cell carcinoma at a tertiary level referral hospital in Hyderabad, India: a 5-year retrospective study

Background: To study the demographics and histopathological patterns of Oral Squamous Cell Carcinoma (OSCC) reported at a tertiary level referral teaching hospital in Hyderabad, India. Materials and Methods: An institutional retrospective study of biopsies sent to a tertiary level referral teaching hospital, Hyderabad. The data was collected year-wise for a period of 5 years from 2007 to 2011 with reference to age, sex, site involved and final diagnosis based on the histopathological findings. Results: A total of 1,005 oral biopsies were reviewed. Of these, OSCC was seen in 234 cases (23.28%). Buccal mucosa (47.7%) was the most frequently involved site followed by tongue (27.6%). Most of the OSCC patients were in the age group of 41 to 50 years, males and histopathologically well-differentiated (62%). Conclusion: This study showed that OSCC is widespread in the patients of this region