Participation of Phosphatidylinositol-3 Kinase Signalling in Human Chorionic Gonadotropin, Bovine Insulin (B-Insulin) and Human-Insulin-Like Growth Factor-I Induced Oocyte Maturation and Steroidogenesis in the Grey Mullet, Mugil Cephalus.

CONTEXT: The grey mullet, Mugil cephalus, is an edible fish of high economic importance. Breeding biology with reference to hormonal/growth factor regulation of oocyte maturation needs to be known for its commercial production. OBJECTIVE: The present study was conducted to examine the potency of maturation inducing hormones, chorionic gonadotropin (hCG), bovine-insulin, and insulin like growth factor1 (h-IGF-1) I on ovarian steroidogenesis and oocyte maturation. DESIGN: The role of hormones and growth factors on steroidogenesis and oocyte maturation was investigated using specific inhibitors, Wortmannin for phosphatidylinositol-3 (PI3) kinase, trilostane for 3ß-hydroxysteroid dehydrogenase, 1-octanol and 1-heptanol for gap junctions, actinomycin D for transcription and cycloheximide for translation of signal molecules. METHODS: Actions of hormonal and growth factors were examined for steroidogenesis, by radioimmunoassay and oocyte maturation by germinal vesicle breakdown (GVBD). Specific inhibitors were used to determine the cell signaling pathways, PI3 kinase. RESULTS: All the inhibitors attenuated the hCG-induced oocyte maturation (GVBD%), steroidogenesis including transcription, translation, gap junctions and PI3 kinase signaling. These inhibitors failed to inhibit h-IGF-I and b-insulin-induced oocyte maturation, steroidogenesis, translation and PI3 kinase signaling. CONCLUSION: hCG induces oocyte maturation via steroid dependent pathway involving gap junctions, transcription, translation and PI3 kinase signaling, unlike h-IGF-I and b-insulin in the mullet.

Human papillomavirus infection mediates response and outcome of vulvar squamous cell carcinomas treated with radiation therapy.

PURPOSE: Human papillomavirus (HPV) is implicated as a causative factor in vulvar squamous cell carcinoma (VSCC). This study evaluates if p16-positivity, a surrogate for HPV, predicts for better response rates to chemoradiation therapy and survival. MATERIALS AND METHODS: We conducted a retrospective chart review of women treated with neoadjuvant or definitive chemoradiation (CRT) therapy from 2000 to 2016 for VSCC. p16 stain-positivity was defined as diffuse strong "block" immunoreactivity within invasive tumor. RESULTS: Seventy-three women with median follow-up of 13.4 months were analyzed. Thirty-three (45.2%) had p16+ tumors. Median age was 73 years (range: 37-89); with p16+ tumors, the median age was 60 years vs 73 years for women with p16- tumors (p < 0.001). The distribution of tumor size and stage by p16-status were similar. The complete clinical response (cCR) rate for p16+ tumors was 63.6% vs 35.0% for p16- tumors (p = 0.014). The pathologic complete response (pCR) rate for women treated neoadjuvantly was 53.8% vs 31.4% for p16+ vs p16-, respectively (p = 0.067). The combined complete response (cCR orpCR [CCR]) rate was 63.6% for p16+ and 30.0% for p16- (p = 0.004). Two-year vulvar control (VC) for women with p16+ tumors was 75.5% vs. 49.5% for p16- (p = 0.008). In women with p16+ tumors who achieved CCR, 2-year VC was 92.3% vs 52.1% for CIR (p = 0.009). For p16- tumors, 2-year VC was 67.3% vs 41.1% for CCR and CIR (p = 0.072). No woman with a p16+ tumor developed distant metastases vs. 7 with p16- tumor (p = 0.013). OS was not statistically different between p16+ cohorts, but was improved for p16- patients with CR vs CIR, 72.9% vs 18.8% (p = 0.026). CONCLUSIONS: p16-positive tumors appear to have better clinical and pathologic response rates and clinical outcomes.

ARECOLINE CANNOT ALTER PINEAL-TESTICULAR RESPONSES TO METABOLIC STRESS IN WISTAR RATS.

CONTEXT: Betel nut is consumed by millions of people for stress reduction and increased capacity to work. One of its components is arecoline which is useful for Alzheimer and schizophrenia; it also influences endocrine and gonadal functions. OBJECTIVE: Objective is to examine whether arecoline can influence pineal-testicular function in metabolic stress. DESIGN: Rats were deprived of food or water or treated them with arecoline, each separately for 5 days. SUBJECTS: Pineal and testis with sex accessories were studied. METHODS: Ultrastructural (pineal, testis, Leydig cells and prostate), hormonal (melatonin and testosterone) and other parameters (fructose and sialic acid) were examined. Pineal indoleamines were quantitated by fluorometric method; testosterone by ELISA, and carbohydrate fractions by spectrophotometric methods. RESULTS: Inanition/ water deprivation caused pineal stimulation ultrastructurally (with enlarged synaptic ribbons) and elevation of melatonin level, but reproductive dysfunction by ultrastructural degeneration of Leydig cells and prostate with fall of testosterone, fructose and sialic acid concentrations. Arecoline treatment showed reversed changes to those of metabolic stress, but arecoline treatment in metabolic stress showed same results as in metabolic stress. CONCLUSION: The findings suggest that arecoline cannot alter the action of metabolic stress on pineal-testicular activity in rats.

Comparative evaluation of micro-leakage of two newer glass ionomer cements in primary molars immersed in three beverages: in vitro study

Introduction: The dietary habits of children expose the oral cavity to challenging environments. A durable interface between the restorative material and tooth surface is essential to ensure marginal integrity thereby contributing to the longevity of restoration. Objectives: The objective of this study was to compare the micro-leakage of two newer glass ionomer cements (SDI Riva Self Cure GIC and GC Fuji IX GP EXTRA) in primary molars immersed in sugarcane juice, chocolate milk and mango drink. Methods: The study included 60 extracted non carious upper and lower primary molars. The buccal and lingual surfaces were restored with SDI Riva Self Cure GIC and GC Fuji IX GP EXTRA respectively. The sample was divided into three groups (chocolate milk, mango drink, sugarcane juice). Each group (n=18) was further subdivided into three subgroups based on the immersion regime. Six teeth were kept as control. The teeth were immersed in Rhodamine B dye. Following this, micro-leakage was determined under 40 x stereomicroscope. Results: Both the materials showed micro leakage when immersed in the three beverages. When specimen under each group were compared, the microleakage score increased with an increase in immersion frequency. This was not statistically significant. The microleakage values for both the materials immersed in the three beverages were not significant. Conclusions: Both the materials used in this study can be conveniently used in restoration of primary molars.

DUAL ACTION OF ARECOLINE ON ADRENAL FUNCTION AND GLUCOSE-GLYCOGEN HOMEOSTASIS IN METABOLIC STRESS IN MICE.

BACKGROUND: People chew betel nut (Areca catechu) for physical work and stress reduction, but it contains arecoline, which has both therapeutic value and untoward effects on endocrine and gonadal functions. OBJECTIVE: Aim of the present study is to investigate its role on adrenal with its target in metabolic stress in mice. MATERIALS AND METHODS: Mice were deprived of water / food, each for 5 days / treated with arecoline (10 mg / kg body wt daily for 5 days) / arecoline after water or food deprivation, for 5 days each. RESULTS: Water or food-deprivation caused adrenocortical hyperactivity, evident from abundance of enlarged mitochondria and smooth endoplasmic reticulum (SER) with elevation of corticosterone level (C: 68.31 ± 2.30, WD: 159.31 ± 4.10 / FD: 194.12 ± 3.40 µg/ mL). Arecoline treatment alone or in water deprivation (C: 68.31 ± 2.30, AR: 144.50 ± 4.33, AR+WD: 194.42 ± 3.35 µg/ mL) / food deprivation (AR + FD: 180.89 ± 4.51 µg/ mL) stress also stimulated adrenocortical activity as recorded in metabolic stress. In contrast, adrenomedullary activity was not altered following water/ food deprivation. Arecoline treatment alone or in metabolic stress suppressed adrenomedullary activity by showing depletion of chromaffin granules (E/NE?), epinephrine (E) and norepinephrine (NE) concentrations. Both the stress decreased blood glucose and liver glycogen levels. Arecoline treatment decreased blood glucose level, with a rise in liver glycogen level, but elevated blood glucose level in water deprivation unlike in starvation. CONCLUSION: Arecoline alone or in metabolic stress involves adrenal and probably other endocrine glands (pancreas, posterior pituitary and rennin-angiotensin system) to maintain homeostasis in metabolic stress in mice.

Modeling non-syndromic autism and the impact of TRPC6 disruption in human neurons.

An increasing number of genetic variants have been implicated in autism spectrum disorders (ASDs), and the functional study of such variants will be critical for the elucidation of autism pathophysiology. Here, we report a de novo balanced translocation disruption of TRPC6, a cation channel, in a non-syndromic autistic individual. Using multiple models, such as dental pulp cells, induced pluripotent stem cell (iPSC)-derived neuronal cells and mouse models, we demonstrate that TRPC6 reduction or haploinsufficiency leads to altered neuronal development, morphology and function. The observed neuronal phenotypes could then be rescued by TRPC6 complementation and by treatment with insulin-like growth factor-1 or hyperforin, a TRPC6-specific agonist, suggesting that ASD individuals with alterations in this pathway may benefit from these drugs. We also demonstrate that methyl CpG binding protein-2 (MeCP2) levels affect TRPC6 expression. Mutations in MeCP2 cause Rett syndrome, revealing common pathways among ASDs. Genetic sequencing of TRPC6 in 1041 ASD individuals and 2872 controls revealed significantly more nonsynonymous mutations in the ASD population, and identified loss-of-function mutations with incomplete penetrance in two patients. Taken together, these findings suggest that TRPC6 is a novel predisposing gene for ASD that may act in a multiple-hit model. This is the first study to use iPSC-derived human neurons to model non-syndromic ASD and illustrate the potential of modeling genetically complex sporadic diseases using such cells.

Investigating the influence of Na+ and Sr2+ on the structure and solubility of SiO2-TiO2-CaO-Na2O/SrO bioactive glass.

This study was conducted to determine the influence that network modifiers, sodium (Na+) and strontium (Sr2+), have on the solubility of a SiO2-TiO2-CaO-Na2O/SrO bioactive glass. Glass characterization determined each composition had a similar structure, i.e. bridging to non-bridging oxygen ratio determined by X-ray photoelectron spectroscopy. Magic angle spinning nuclear magnetic resonance (MAS-NMR) confirmed structural similarities as each glass presented spectral shifts between -84 and -85 ppm. Differential thermal analysis and hardness testing revealed higher glass transition temperatures (Tg 591-760 °C) and hardness values (2.4-6.1 GPa) for the Sr2+ containing glasses. Additionally the Sr2+ (~250 mg/L) containing glasses displayed much lower ion release rates than the Na+ (~1,200 mg/L) containing glass analogues. With the reduction in ion release there was an associated reduction in solution pH. Cytotoxicity and cell adhesion studies were conducted using MC3T3 Osteoblasts. Each glass did not significantly reduce cell numbers and osteoblasts were found to adhere to each glass surface.

Contextual modulation of androgen effects on agonistic interactions.

Seasonal changes in steroid hormones are known to have a major impact on social behavior, but often are quite sensitive to environmental context. In the bi-directionally sex changing fish, Lythrypnus dalli, stable haremic groups exhibit baseline levels of interaction. Status instability follows immediately after male removal, causing transiently elevated agonistic interactions and increase in brain and systemic levels of a potent fish androgen, 11-ketotestosterone (KT). Coupling KT implants with a socially inhibitory environment for protogynous sex change induces rapid transition to male morphology, but no significant change in social behavior and status, which could result from systemically administered steroids not effectively penetrating into brain or other tissues. Here, we first determined the degree to which exogenously administered steroids affect the steroid load within tissues. Second, we examined whether coupling a social environment permissive to sex change would influence KT effects on agonistic behavior. We implanted cholesterol (Chol, control) or KT in the dominant individual (alpha) undergoing sex change (on d0) and determined the effects on behavior and the degree to which administered steroids altered the steroid load within tissues. During the period of social instability, there were rapid (within 2 h), but transient effects of KT on agonistic behavior in alphas, and secondary effects on betas. On d3 and d5, all KT, but no Chol, treated females had male typical genital papillae. Despite elevated brain and systemic KT 5 days after implant, overall rates of aggressive behavior remained unaffected. These data highlight the importance of social context in mediating complex hormone-behavior relationships.

Comparative evaluation of hand and rotary file systems on dentinal microcrack formation during pulpectomy procedure in primary teeth: an in vitro study.

PURPOSE: Pulpectomy can be used for the management of deep dentinal carious lesions in primary teeth which can be restored. Mechanical preparation of root canals can be performed using hand or NiTi rotary files. However, this may cause dentinal stress and consequently dentinal microcracks. Hence, the aim was comparative evaluation of hand and rotary file systems on dentinal microcrack formation during pulpectomy procedure in primary teeth. METHODS: 60 extracted primary molar teeth were selected comprising of 80 root canals. Simple random sampling was used to divide root canals into four groups (n = 20): Group A-Hedstrom file, Group B-Pro AF Baby Gold rotary, Group C-ProTaper Next rotary, and Group D-unprepared group. Assessment was conducted on presence or absence of microcracks using Chi square test (p < 0.05). RESULTS: The total number of microcracks in Group A: one (5%), Group B: four (20%), Group C: nine (45%) and Group D: zero (0%) which was statistically significant (p = 0.002). At cervical third, the number of microcracks seen with Group A: one (5%), Group B: zero (0%), Group C: five (25%) and Group D: zero (0%) (p = 0.005). At the middle third, the number of microcracks seen in Group A: zero (0%), Group B: four (20%), Group C: four (20%) and Group D: zero (0%) (p = 0.029). CONCLUSION: The study concluded that dentinal microcracks are formed with both hand and rotary file systems in primary teeth. ProTaper Next showed significantly higher number of microcracks, followed by ProAF Baby Gold and H files.

Comparative evaluation of shear bond strength of three different glass ionomer cement (conventional, zirconium-reinforced and advanced glass hybrid) in primary molars: an in vitro study.

PURPOSE: The success of restorative materials is largely dependent on their capacity to adhere to the tooth structure and withstand the various forces present in the oral cavity. So, the aim of present study was to evaluate and compare the shear bond strength (SBS) of Type IX Glass Ionomer Cement (GIC), Zirconomer, and Gold Label Hybrid GIC in primary molars. METHODS: Thirty primary molars were selected based on inclusion and exclusion criteria. The molars were polished to provide a flat dentin surface after being inserted in auto polymerizing acrylic resin. The samples were randomly divided into three groups, equally and were bonded to GIC. On the dentin surface, restoration cylinders were made using a plastic mould that had an internal diameter and height of 5 mm and 3 mm, respectively. The cement was manipulated according to the manufacturer's directions through the plastic mould. Then, the samples were stored at room temperature for 10 days to mimic oral conditions. The Universal Testing Machine was used to test SBS. One-way ANOVA and the post hoc Tukey test were used to statistically assess the collected data. RESULTS: A statistically significant difference was found in all three groups (p < 0.01), with Zirconomer demonstrating highest SBS, followed by Type IX GIC and Gold Label Hybrid GIC. CONCLUSION: The SBS value of Zirconomer was better when compared to Type IX GIC and Gold Label Hybrid GIC.

Bioleaching of low-grade uranium ore using Acidithiobacillus ferrooxidans.

Bioleaching of uranium was carried out with Turamdih ore sample procured from Uranium Corporation of India Limited, Jaduguda. The bacterial strain that was used in the leaching experiments was isolated from the Jaduguda mine water sample. Efficiency of bioleaching was studied by varying parameters like pulp density and initial ferrous concentration as source of energy. It is observed that the efficiency of bioleaching was 49% at 10% pulp density (w/v) and initial pH 2.0. Addition of external has no effect on efficiency of bioleaching showing domination of direct leaching mechanism over indirect.

Intubation in the Intensive Care Unit: C-MAC video laryngoscope versus Macintosh laryngoscope.

PURPOSE: Various modifications of the Macintosh blade and direct laryngoscopy have been incorporated into practice to improve the intubation success rate and avoid complications while ensuring patient safety. This study evaluates the usefulness of two different direct laryngoscopy methods used by operators with various level of experience in the Intensive Care Unit. MATERIAL AND METHODS: In a single centre prospective study, C-MAC and Macintosh laryngoscopes were compared in terms of laryngoscopy and intubation outcomes such as glottic visualization, number of intubation attempts, intubation success and satisfaction score. RESULTS: During the one-year study period, 263 patients were evaluated and data of 218 patients were analyzed. The rate of successful first attempt intubation was higher in the video laryngoscope group (VL) (84% vs 57%; P<0.001). A significantly greater number of patients in the Macintosh laryngoscopy group had difficult visualization of the glottis in terms of the modified Cormack and Lehane classification and Percentage of Glottic Opening scale. CONCLUSION: The use of video laryngoscope for intubation in ICU settings results in better visualization of the glottis and a higher incidence of successful intubation attempts.

Genomic alterations driving psoriasis pathogenesis.

Psoriasis is an immune mediated inflammatory skin disease with complex etiology involving interplay between environmental and genetic risk factors as disease initiating event. Enhanced understanding on genetic risk factors, differentially expressed genes, deregulated proteins and pathway-targeted therapeutics have established multiple axis of psoriasis pathogenesis. So far, loci in 424 genes are reported to be associated with psoriasis alongside copy number variations and epigenetic alterations. From clinical perspective, presence of specific genetic trigger(s) in individual psoriasis patient could aid in devising a personalized therapeutic strategy. Therefore, the review presents an updates on reported genomic alterations and their subsequent course of cutaneous inflammations that potentially drive to psoriasis.

Detection of Bacterial Pathogens in Cerebrospinal Fluid using Restriction Fragment Length Polymorphism.

BACKGROUND: Polymerase chain reaction (PCR) is useful for rapid microbial detection in body fluids with low microbial load. It is easier to use universal or broad range primers for the amplification of conserved stretches of DNA common to all bacteria like 16S rRNA gene, followed by restriction fragment length polymorphism (RFLP) of PCR products. METHODS: Forty samples of cerebrospinal fluid were collected. After DNA extraction, universal or broad range PCR was performed using two universal primers U1-5'-CCAGCAGCCGCGGTAATACG-3', corresponding to nucleotides 518 to 537 of the Escherichia coli 16S rRNA gene, and U2 - 5'-ATCGG(C/T)TACCTTGTTACGACTTC-3', corresponding to nucleotides 1513 to 1491 of the same gene. The PCR product was subjected to digestion by endonucleases- HaeIII, Mn11, BstB1 and Alu1. Restriction pattern obtained was compared with that of standard organisms to identify the pathogen. The results were compared with conventional methods. RESULT: Universal PCR could detect pathogens in 20% samples within 13-18 hours as compared to 16% by conventional methods. The analytical sensitivity was 10 Gram negative and 250 Gram positive organisms per 200 µl sample. Overall sensitivity was 83.3% and specificity was 91.2%. CONCLUSION: Universal PCR followed by RFLP of PCR product is a good alternative to conventional diagnosis of bacterial pathogens.

Multiple systems for recognition of apoptotic lymphocytes by macrophages.

In vivo, apoptotic lymphocytes are recognized and phagocytosed by macrophages well before the final stages of DNA degradation and cell lysis. The recognition process is apparently triggered by the exposure of phosphatidylserine (PS) on the cell surface, an event which precedes cell lysis by several hours. However, multiple receptors appear to respond to this event. We demonstrate here that both activated and unactivated macrophages recognize PS, but with different receptor systems. Phagocytosis of apoptotic lymphocytes by activated (but not by unactivated) macrophages is inhibited by pure PS vesicles as well as by N-acetylglucosamine, implicating involvement of a lectin-like receptor in this case. Conversely, uptake of apoptotic lymphocytes by unactivated (but not by activated) macrophages is inhibited by PS on the surface of erythrocytes as well as by the tetrapeptide RGDS and cationic amino acids and sugars, implicating involvement of the vitronectin receptor in this case. Recognition by both classes of macrophages is blocked by the monocyte-specific monoclonal antibody 61D3. The signal recognized by activated macrophages appears to develop on the lymphocyte prior to assembly of the signal recognized by unactivated macrophages. Collectively, these results suggest that PS exposure on the surface of apoptotic lymphocytes generates a complex and evolving signal recognized by different receptor complexes on activated and unactivated macrophages.

Intestinal protozoal infestation profile in persistent diarrhea in children below age 5 years in western Nepal.

Unlike acute diarrhea, the role of pathogens in persistent diarrhea in children in Nepal is unclear. Protozoal parasites are suspected to be a major cause. The study was carried out to find the association between protozoal agents and persistent diarrhea in children below age 5 years from western Nepal. Stool samples were collected from 253 children with persistent diarrhea, from 155 children with acute diarrhea (disease controls) and from 100 healthy children from the community (normal controls). Of 253 children with persistent diarrhea, 90 (35.5%) had protozoal infections, 63 (24.9%) helminthic infections, 32 (12.6%) had bacterial infections and 16 had mixed infections. Giardia lamblia was the most prevalent (67.7%), followed by Entamaeba histolytica (27.7%). HIV infection and severe malnutrition were associated with Cyclospora cayetanensis and Cryptosporidium spp causing persistent diarrhea. We conclude that stool microscopy should be routinely performed in children with persistent diarrhea since protozoal infections can be cured with effective treatment and control can be achieved by proper health education.

Comparative evaluation of endodontic management of teeth with unformed apices with mineral trioxide aggregate and calcium hydroxide.

PURPOSE: The purpose of this study was to compare mineral trioxide aggregate (MTA) and calcium hydroxide (Ca(OH)2) for their efficacies and time taken for formation of apical biological calcific barriers and resolution of periapical radiolucencies, if present at baseline, in teeth with unformed apices. METHODS: Twenty nonvital permanent maxillary incisors with unformed apices, stratified according to the size of periapical radiolucencies and stage of root development, were equally allocated to MTA and Ca(OH)2 groups. In group 1 (MTA group), after 7 days of disinfection with Ca(OH)2, MTA was packed into the apical one third of the root canals and obturation with gutta percha (GP) was performed in 90% (9/10) of cases within 15 to 30 days. In group 2 (Ca(OH)2 group), obturation was performed following clinical and radiographic depiction of the apical stop. RESULTS: The mean time taken for apical biological barrier formation was 3 +/- 2.9 months for group 1 and 7 +/- 2.5 months for group 2 (P=.008). The periapical radiolucencies were resolved in 4.6 +/- 1.5 months for group 1 and 4.4 +/- 1.3 months for group 2 (P=.83). The total treatment was completed in 0.75 +/- 0.4859 months and 7 +/- 2.5 months for groups 1 and 2, respectively. CONCLUSION: The 2 materials were found to be equally efficacious in the management of nonvital teeth with unformed apices. Time taken to complete the treatment and the biological barrier formation in group 1 was significantly less than that for group 2. The healing time for periapical radiolucencies was almost identical.

Investigating the structure and biocompatibility of niobium and titanium oxides as coatings for orthopedic metallic implants.

Applying sol gel based coatings to orthopedic metallic implant materials can significantly improve their properties and lifespan in vivo. For this work, niobium (Nb2O5) and titanium (TiO2) oxides were prepared via solution processing in order to determine the effect of atomic arrangement (amorphous/crystalline) on bioactivity. Thermal evaluation on the synthesized materials identified an endotherm for Nb2O5 at 75 °C with 40% weight loss below 400 °C, and minimal weight loss between 400 and 850 °C. Regarding TiO2 an endotherm was present at 92 °C with 25% weight loss below 400 °C, and 4% between 400 and 850 °C. Phase evolution was determined using High Temperature X-ray Diffraction (HT-XRD) where amorphous-Nb2O5 (450 °C), hexagonal-Nb2O5 (525 °C), orthorhombic-Nb2O5 (650 °C), amorphous-TiO2 (275 °C) and tetragonal TiO2 (500 °C) structures were produced. Simulated body fluid (SBF) testing was conducted over 1, 7 and 30 days and resulted in positive chemical and morphological changes for crystalline Nb2O5 (525 °C) and TiO2 (500 °C) after 30 days of incubation. Rod-like CaP deposits were observed on the surfaces using Scanning Electron Microscopy (FE-SEM) and Grazing Incidence-X-ray Diffraction (GI-XRD) shows that the deposits were X-ray amorphous. Cell viability was higher with the TiO2 (122%) samples when compared to the growing cell population while Nb2O5 samples exhibited a range of viability (64-105%), partially dependent on materials atomic structure.

RNA synthesis in Yoshida ascites tumor cells after ultraviolet and gamma irradiation.

The residual RNA synthesis in Yoshida ascites tumor cells following exposure to ultraviolet radiation was insensitive to rifampicin AF/013, an inhibitor of initiation of RNA synthesis in eukaryotic cells. On the other hand, residual RNA synthesis in the ascites tumor cells after gamma-irradiation was inhibited by rifampicin AF/013. In vitro synthesis of RNA on ultraviolet-irradiated ascites chromatin likewise was resistant to rifampicin AF/013. Ultraviolet irradiation was found to decrease the number of RNA chain initiation sites on ascites chromatin considerably whereas the number of initiation sites on ascites chromatin increased considerably after gamma irradiation. These results indicate that ultraviolet irradiation may preferentially affect the DNA segments participating in initiation of RNA synthesis.