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S Mitra

Publications and source records attributed to S Mitra.

At least 415 records · Page 23Linked to original sources
PubMedDate not supplied

Stress, diet and alcohol-induced oxidative gastrointestinal mucosal injury in rats and protection by bismuth subsalicylate.

Oxygen free radicals are implicated in the pathogenesis of stress and food/alcohol-induced gastrointestinal injury. We have investigated the effects of restraint stress, spicy food diet, high-fat diet and 40% ethanol on the enhanced production of reactive oxygen species, including superoxide anion and hydroxyl radicals, and on DNA fragmentation, lipid peroxidation and membrane microviscosity (indices of oxidative tissue damage) in gastric and intestinal mucosa of Sprague-Dawley rats. Furthermore, the protective ability of bismuth subsalicylate (BSS; 15 mg kg(-1) was determined against the gastrointestinal mucosal injury induced by these stressors. Animals on the high-fat diet consumed 31% more food as compared to other animals. Animals on the spicy food diet consumed ca. 23% more water as compared to control animals, and the high-fat diet animals consumed 17% less water. Restraint stress provided greater injury to both gastric and intestinal mucosa as compared to other stressors. Restraint stress, spicy food diet, high-fat diet and ethanol increased superoxide anion production by 10.0-, 4.3-, 5.7- and 4.8-fold, respectively, in the gastric mucosa, and by 10.4-, 5.3-, 7.0- and 5.5-fold in the intestinal mucosa. Exposure to restraint stress, spicy food diet, high-fat diet and 40% ethanol also increased hydroxyl radical production by ca. 14.3-, 4.5-, 3.5- and 4.8-fold, respectively, in the gastric mucosa, and by 17.0-, 4.8-, 3.5- and 4.7-fold in the intestinal mucosa. Bismuth subsalicylate administration to the animals provided significant protection against superoxide anion and hydroxyl radical production. Restraint stress, spicy food diet, high-fat diet and ethanol increased lipid peroxidation by 3.6-, 2.4-, 2.6- and 2.0-fold, respectively, in the gastric mucosa, and by 4.1-, 3.5-, 3.6- and 2.7-fold in intestinal mucosa. Administration of BSS decreased restraint stress, spicy food diet, high-fat diet and ethanol-induced gastric mucosal lipid peroxidation by ca. 26%, 36%, 45% and 18%, and intestinal mucosa lipid peroxidation by 20%, 21%, 46% and 42%, respectively. Approximately 4.0-, 2.0-, 2.4- and 2.0-fold increases in DNA fragmentation were observed in the gastric mucosa of rats exposed to restraint stress, spicy food diet, high-fat diet and 40% ethanol, respectively, and similar increases in the intestinal mucosa. These same four stressors increased membrane microviscosity by 11.6-, 6.1-, 7.3- and 5.4-fold, respectively, in the gastric mucosa, and by 16.2-, 7.9-, 9.5- and 7.8-fold in the intestinal mucosa. Bismuth subsalicylate exerted significant protection against DNA damage and changes in membrane microviscosity induced by the four stressors. Excellent correlations existed between the production of reactive oxygen species and the tissue damaging effects in both gastric and intestinal mucosa. In summary, the results demonstrate that physical and chemical stressors can induce gastrointestinal oxidative stress and mucosal injury through enhanced production of reactive oxygen species, and that BSS can significantly attenuate gastrointestinal injury by scavenging these reactive oxygen species.

Animals↗
PubMedDate not supplied

A proposed three-phase counting system for the in vivo measurement of the major elements using pulsed 14 MeV neutrons.

It is proposed to employ a pulsed source of 14 MeV neutrons for in vivo activation analysis. This would permit the differentiation, with time, of the resulting gamma ray emission into three separate spectra, according to the type of nuclear reaction and mode of decay. The three-phase counting has been divided into approximately 10 microseconds during "beam-on," and 200 and 800 microseconds during "beam-off." Measurements of the major elements, C, N, O, Cl, and P, to give nutritionally-important body compartments of total body fat, protein, water, minerals, and extracellular water, thus is expected with a single scan.

Body Composition↗
PubMedDate not supplied

Role of carcinogen-modified deoxynucleotide precursors in mutagenesis.

Agents which damage or modify cellular DNA will generally also modify the nucleotide precursor pools, sometimes preferentially (Topal and Baker, 1982). There are at least two different ways that incorporation of modified (possibly promutagenic) nucleotides could, theoretically, make a significant contribution to the mutations induced by these agents. Modified bases may exhibit ambiguous base pairing and produce mutations during normal replication or they may induce secondary mutations as a result of processing subsequent to incorporation. There are important precedents for such possibilities. Classical studies on mutagenesis with prototype mutagens like 2-aminopurine (2-AP) and 5-bromouracil clearly show that mutations can occur by incorporation of deoxynucleotides of tautomeric or ionized (Sowers et al., 1987) bases into newly synthesized DNA (Ronen, 1979; Lasken and Goodman, 1984, Coulondre and Miller, 1977). 5-Hydroxymethyl-2'-deoxyuridine (HMdU), a product of oxidative DNA damage, can also be (re)incorporated into cellular DNA with both toxic and mutagenic consequences (Kaufman, 1987; Shirname-More et al., 1987). Furthermore, modified nucleotides may alter the pool sizes of the normal nucleotides and indirectly produce toxic and mutagenic effects. However, these effects are generally seen at high, nonphysiological, concentrations of the modified precursors and may not be relevant under physiological conditions. The relative importance of modified deoxynucleotide precursors in the production of mutations by alkylating and oxidative DNA-damaging agents is discussed.

Animals↗
PubMedDate not supplied

Tissue-specific variation in repair activity for 3-methyladenine in DNA in two stocks of mice.

Two stocks of mice, hybrid (C3H X 101)F1 and inbred SEC/R1, were compared for 3-methyladenine-DNA N-glycosylase activity which is involved in removal of 3-methyladenine, 7-methylguanine and some other N-methylpurines in DNA, in cell-free extracts of different tissues. Based on activity measured both per unit weight of tissue and per mass DNA, there is a significant organ-specific and stock-specific difference in N-glycosylase activity over a range of 0.5-8.7 fmoles of 3-methyladenine released per h at 37 degrees C per micrograms DNA of tissue extract. On a per cell basis, the repair activity for 3-methyladenine is the highest in stomach in both stocks. The tissue can be arranged in order of decreasing activity of glycolytic removal as stomach greater than kidney greater than lung greater than liver greater than spleen greater than brain greater than ovary for SEC/R1 mice and stomach greater than kidney greater than ovary greater than spleen, lung and brain greater than liver for the hybrid mice. For all tissues except ovary, SEC/R1 mice have 1.5-4-fold higher specific N-glycosylase activity than (C3H X 101)F1 mice. In contrast, the ovary of SEC/R1 stock has about half as much enzyme activity as that of the hybrid stock.

Adenine↗
PubMedDate not supplied

Calibration of a prototype in vivo total body composition analyser using 14 MeV neutron activation and the associated particle technique.

A prototype in vivo total body composition analyser has been constructed for determining the total body contents of nitrogen (TBN), carbon (TBC) and oxygen (TBO) in young experimental animals such as sheep or pigs by 14 MeV neutron activation using a commercially available associated particle sealed tube neutron generator (APSTNG). The instrument was calibrated by scanning phantoms of different sizes in the mass range 10-36 kg, filled with a mixture of elements as found in a normal human body. Good agreement was found between the measured and expected values of N, O and C when two phantoms of similar dimensions but of different composition were scanned. With four 15 cm x 15 cm cross section and 45 cm long NaI(T1) gamma detectors and a radiation dose of approximately 20 microSv due to neutrons, the expected precisions for a 28 kg animal, CV% (based on counting statistics) are N: 9.3, C: 2.3 and O: 1.4.

Animals↗
PubMedDate not supplied

Alkalinized lidocaine and bupivacaine with hyaluronidase for sub-tenon's ophthalmic block.

BACKGROUND AND OBJECTIVES: Alkalinization of local anesthetics has been shown to decrease the onset and prolong the duration of block for extraconal and intraconal application in ocular surgery. The objective of this study is to determine if alkalinization is also effective in sub-Tenon's block when hyaluronidase is added to the drug mixture. METHODS: Twenty-nine patients were randomly assigned to 2 groups in a double-blind, prospective fashion to receive 5.125 mL of either a plain mixture LBH (2.5 mL lidocaine 2%, 2.5 mL bupivacaine 0.5%, 5 IU/mL hyaluronidase, and 0.125 mL isotonic saline) or pH-adjusted mixture LBH-PH (2.5 mL lidocaine 2%, 2.5 mL bupivacaine 0.5%, 5 IU/mL hyaluronidase, and 0.125 mL sodium bicarbonate 8.4%) of local anesthetics in a 1-quadrant sub-Tenon's block. Time to onset and time to full akinesia were determined every 30 seconds. RESULTS: No difference was found between the study groups. CONCLUSION: pH adjustment of the local anesthetic mixture of lidocaine, bupivacaine, and hyaluronidase offered no additional benefit in sub-Tenon's technique in ocular procedures.

Adult↗
PubMedDate not supplied

Frequency-plane analysis of normal and pathological ECG signals for disease identification.

In this paper a frequency plane analysis of both normal and diseased ECG signals is performed specifically for disease identification. Image processing techniques are used to develop an automated data acquisition package of 12 lead ECG signals from paper records. A regeneration domain is also developed to check the captured pattern with the original wave shape. A QRS complex detector with an accuracy level approximately 98.4% in up to 30% signal to noise level is developed. Discrete Fourier transform (DFT) is performed to obtain the frequency spectrum of every ECG signal. Some interesting amplitude and phase response properties of chest lead V2, V3, V4, V6 and limb lead I, II, III, AVL, AVF are seen. Both amplitude and phase properties are different for normal and diseased subjects and can serve an important role in disease identification. A statistical analysis of amplitude property is carried out to show that this property is significantly different for normal and diseased subjects.

Adult↗
PubMedDate not supplied

On the convergence of Das Gupta's model of fertility projection.

A regression model expressing the age-specific fertility rates at a given point of time as a variable dependent upon the same at the preceding points of time has been developed by Das Gupta for purposes of fertility projection. The model, judged by the values of the multiple correlation coefficients, appears to work very well with the U.S. data set, and it also produces limiting values of the fertility rates when the projection is carried far into the future. The conditions of convergence of such a model have been determined in this paper according to which the model's usefulness for purposes of long-term projection of fertility rates appears to be severely restricted.

Adult↗
PubMedDate not supplied

Human papillomavirus prevalence in postradiotherapy uterine cervical carcinoma patients: correlation with recurrence of the disease.

To understand the role of human papillomavirus (HPV) in recurrence of uterine cervical cancer (CA-CX) after radiotherapy, we have analyzed the HPV prevalence in the exfoliated cells of 56 patients and their corresponding plasma. HPV DNA was detected in exfoliated cells of 78% (44/56) patients (HPV-16, 68%; HPV-18, 14%; HPV-X [other than 16, 18], 11%; and mixed infection of HPV-16 and HPV-18 in three cases). HPV DNA in plasma was present in only 25% (11/44) of the HPV-positive exfoliated cells (positive predictive value, 100%; negative predictive value, 27%) with concordance in HPV types. The recurrence of the disease was significantly associated with the presence of HPV in the exfoliated cell (P= 0.01) and plasma (P= 0.007) as well as high viral load in the exfoliated cell (P= 0.0002). Kaplan-Meier disease-free estimates have also shown the significant association between HPV prevalence in plasma and recurrence of the disease (P= 0.045). Thus, it indicates that in postradiotherapy CA-CX patients, the high viral load in the exfoliated cell as well as HPV presence in the plasma samples could be used in early detection of the patients at increased risk for disease recurrence and progression.

Adult↗
PubMedDate not supplied

A feasibility study of in vivo 14-MeV neutron activation analysis using the associated particle technique.

The feasibility of using the time correlated associated particle technique for in vivo 14-MeV neutron activation analysis has been investigated. Gamma rays following neutron inelastic scattering with nitrogen, carbon, and oxygen have been measured with a 12.5 x 10-cm NaI (T1) detector. The results have been scaled to a proposed facility comprising four such detectors past which the subject would be scanned. Based on counting statistics, the precision of estimation of these elements has been determined to be 2.1%, 1.0%, and 1.1%, respectively, for experimental measurements on a sample containing physiological concentrations of the major body elements. The average body dose level would be restricted to 0.3 mSv.

Alpha Particles↗
PubMedDate not supplied

Purification and characterization of a protein kinase from goat sperm plasma membrane.

A protein kinase that causes phosphorylation of serine and threonine residues of casein has been partially purified from goat cauda-epididymal sperm plasma membrane and characterized. The kinase, solubilized from the membrane with 1.0% Triton X-100, was purified to 480-fold by using DEAE-cellulose and casein-Sepharose affinity chromatographic techniques. The kinase is a strongly basic protein with pI of 9.5. The enzyme has a molecular mass of 310 kilodaltons as estimated by Sephacryl S-300 gel exclusion. The kinase showed affinity for protein substrates in the order membrane proteins > casein > phosvitin > histone > protamine. The apparent Km values of the kinase for casein and membrane proteins were 1 and 0.15 mg/mL, respectively. The synthetic peptides Kemptide and poly(Glu80Tyr20) did not serve as substrates of the enzyme. ATP, rather than GTP or PP(i), is the donor of phosphate for the phosphorylation reaction. Cyclic AMP and GMP, NaCl (0.25 M), KCl (0.25 M), Ca2+, calmodulin, phosphatidylserine, and muscle protein kinase inhibitor had no appreciable effect on the kinase activity. Heparin (0.5 microgram/mL) showed high affinity for inhibiting only 40% of the kinase activity, whereas polyamines at a relatively high concentration (5 mM) inhibited 40-50% of the enzymic activity. The kinase appears to be distinct from other protein kinases including casein kinases. The activity of the kinase derived from the purified sperm plasma membrane was markedly (approximately 90%) lost when the intact spermatozoa were pretreated with diazonium salt of sulfanilic acid, a membrane nonpenetrating surface probe.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Chloromercuribenzenesulfonate↗
PubMedDate not supplied

Maxillary sinus involution after endoscopic sinus surgery in a child: a case report.

Studies in animal models have suggested that functional endoscopic sinus surgery may affect facial skeletal growth in children, although reviews of large clinical series do not support this observation. This is a case report of a 12 year old male referred to the senior author (SBL) several months after undergoing bilateral functional endoscopic sinus surgery. The preoperative computed tomograms of the paranasal sinuses were normal with symmetrical well-developed paranasal sinuses. Postoperative computed tomography revealed nearly total involution of the osseous skeleton of the left maxillary sinus. This is the first clinical report of alterations in the facial skeleton of a child secondary to iatrogenic trauma directed at the osteomeatal complex. The case and related literature are reviewed in detail.

Child↗
PubMedDate not supplied

Recurrent carotid blowout syndrome: diagnostic and therapeutic challenges in a newly recognized subgroup of patients.

BACKGROUND AND PURPOSE: To our knowledge, recurrent carotid blowout syndrome (rCBS) has not been well described. Our purpose was to review our institution's recent experience with patients who presented with multiple episodes of carotid blowout syndrome (CBS), and who were referred for emergent diagnostic angiography and endovascular therapy. METHODS: We retrospectively reviewed the last 46 consecutive patients who had a clinical diagnosis of CBS. All patients were examined and treated prospectively according to a standardized protocol. Most patients (43 of 46) had undergone extensive primary and salvage radical surgery with intraoperative brachytherapy or external beam radiation or both. The remaining three patients had either traumatic or iatrogenic CBS. RESULTS: Twelve patients (26%) in our series had more than one episode of CBS in which a total of 32 (20 recurrent) events were observed (average 2.7, range 2-4). Intervals of rCBS ranged from 1 day to 6 years. Thirteen (65%) of 20 recurrent events were attributed to progressive disease (PD), and seven (35%) of 20 to treatment failures (TFs). In the PD group, seven (54%) of 13 had recurrent ipsilateral disease, and six (46%) of 13 had recurrent contralateral disease. Etiologies of rCBS were as follows: seven exposed carotids; seven carotid pseudoaneurysms; eight small-branch pseudoaneurysms; five tumor hemorrhages; three hyperemic/ulcerated wounds; and one aortic arch rupture. Twenty-seven of 32 events were treated with endovascular therapy, which included the following: nine carotid occlusions; 11 small-branch embolizations; three transarterial tumor embolizations; one carotid stent; and two direct-puncture embolizations. Four of six TFs were retreated successfully with endovascular therapy; the remaining two TFs were managed successfully by surgery. In the PD group, hemorrhagic complications of rCBS were managed successfully in all but one patient, who died. No permanent neurologic or ophthalmologic complications occurred. CONCLUSION: Recurrent CBS is a frequently encountered problem in which most cases are caused by PD resulting from both multifocal iatrogenic arteriopathy and occasional wound complications that are characteristic of aggressively managed head and neck surgical patients. Initial TFs are encountered often as well. Despite the diagnostic and therapeutic challenges of rCBS, most cases can be retreated effectively.

Adolescent↗
PubMedDate not supplied

Monitoring effluents from an air toxic control device using continuous nonmethane organic carbon analyzer.

Nonmethane organic carbon (NMOC) is a measure of total organic carbon other than methane in an air emission. It is a convenient way of expressing total organic emissions in terms of carbon. Development of a continuous NMOC (referred to as the C-NMOC) analyzer was recently reported. A microsorbent trap called the microtrap is the key component of this instrument. The microtrap selectively concentrates the organic compounds and then desorbs them as an injection pulse for NMOC detection. The process of concentration and injection is quite fast, and the analysis can be carried out every few seconds to every few minutes. The characteristics of this instrument as applied to on-line monitoring are presented in this article. Its applicability is demonstrated by monitoring emissions from an air toxic control device. The instrument performed well with the oxygenated, chlorinated, aliphatic, and aromatic hydrocarbons in this study. The instrument also demonstrated linear response and high sensitivity.

Air Pollutants↗