Inhibition in radiation mediated cellular toxicity by minimizing free radical flux: one of the possible mechanisms of biological protection against lethal ionizing radiation by a sub- fraction of Podophyllum hexandrum

The study has focused on exploring the mechanism of action of Podophyllum hexandrum sub-fraction (G-001M) exhibiting >90% protection in lethally irradiated mice. Currently, G-001M was assessed for antioxidant characteristics by evaluating DPPH, superoxide and hydrogen peroxide radical formation, anti-lipid per oxidation, metal chelation and total flavonoid content. To affirm cytoprotective efficacy of G-001M, plasmid DNA protection, blood WBC counts, marker for lipid peroxidation (MDA) and antioxidant status (GSH) in mice splenocytes and thymocytes were studied. G-001M, having high amount of total phenolic contents (200±10mg, w/w), exhibited dose dependent inhibition in DPPH and superoxide radical formation. Hydrogen peroxide radical scavenging was higher than standards. With pre-treatment of G-001M, plasmid DNA was also maximally restored to supercoiled form. Radiation modulated MDA and GSH values in splenocytes and thymocytes of mice altered significantly after 24 hrs and at later intervals, values were close to the controls. Radiation mediated losses in WBC counts were significantly regained (p<0.001) in G-001M pre-treated irradiated mice. The above findings explicitly conveyed that G-001M has successfully minimized radiation inflicted free radicals generation and their multiplication. This activity of G-001M could be undoubtedly among one of the major modes of action in extending whole body survival in lethally irradiated mice.

Cardio-respiratory reflexes evoked by phenylbiguanide in rats involve vagal afferents which are not sensitive to capsaicin

AIM

Stimulation of pulmonary C fibre receptors by phenylbiguanide (PBG, 5-HT(3) agonist) produces hypotension, bradycardia and tachypnoea or apnoea. However, tachypnoeic or apnoeic responses are not consistent. Therefore, this study was undertaken to delineate the actions of PBG on respiration and compared with those evoked by capsaicin (TRPV1 agonist).

METHODS

Blood pressure, respiratory excursions and ECG were recorded in urethane anaesthetized adult rats. The effect of PBG or capsaicin was evaluated before and after ondansetron (5-HT(3) antagonist), capsazepine (TRPV1 antagonist) or bilateral vagotomy. In addition, their effect on vagal afferent activity was also evaluated.

RESULTS

Bolus injection of PBG produced concentration-dependent (0.1-100 microg kg(-1)) hypotensive and bradycardiac responses, while there was tachypnoea at lower concentrations (0.1-3 microg kg(-1)) and apnoea at higher concentrations (10-100 microg kg(-1)). After vagotomy or after exposure to ondansetron both tachypnoeic and apnoeic responses were abolished along with cardiovascular responses. However, capsazepine (3 mg kg(-1)) did not block the PBG-induced reflex responses. Capsaicin (0.1-10 microg kg(-1)), on the other hand, produced a concentration-dependent apnoea, hypotension and bradycardia but tachypnoea was not observed. Ondansetron failed to block the capsaicin-induced reflex response while bilateral vagotomy abolished bradycardiac and hypotensive responses and attenuated the apnoeic response. In another series, vagal afferent activity and cardio-respiratory changes evoked by PBG were blocked by ondansetron. However, capsaicin failed to activate the PBG-sensitive vagal afferents even though cardio-respiratory alterations were observed.

CONCLUSIONS

The present observations indicate that PBG produced tachypnoea at a lower concentration and apnoea at a higher concentration involving vagal afferents which are different from those excited by capsaicin.

Familial hypoparathyroidism

A family with hereditary (familial) hypoparathyroidism is reported where three of the total four siblings were affected and each presented with different manifestation-one brother with refractory epilepsy since early childhood, another brother with unilateral extrapyramidal features in adult life, and their only sister having recurrent attacks of tingling and numbness due to hypocalcemia since 12 years of age.

Profile of tuberculous meningitis with or without HIV infection and the predicators of adverse outcome

OBJECTIVES

To compare the clinical, radiological and cerebrospinal fluid (CSF) findings, at hospital admission, among adult patients with tuberculous meningitis (TBM) with or without HIV infection and to identify the factors that predict adverse outcome at six months.

METHODS

A total of 82 adult patients with TBM were included (40 HIV-positive and 42 HIV-negative). Several clinical (duration of illness, Glasgow Coma Scale score, presence of high temperature, headache, cranial nerve or sphincter abnormality, seizures and endocrine dysfunction), radiological (presence of hydrocephalus, cerebral infarction and oedema, meningeal enhancement, granuloma) and cerebrospinal fluid parameters (glucose, protein, lactate, lymphocytes, neutrophils and adenosine deaminase values) were recorded along with CD4 count in the peripheral blood. Statistical analysis was performed using the chi-square test. Individual variables were evaluated as prognostic factors for adverse outcome in both groups by calculating the relative risk of association for each.

RESULTS

Temperature more than 38.33 degrees C was more common in the HIV-negative group while seizures, hydrocephalus, cerebral infarction and low CD4 count occurred significantly more commonly in the HIV-positive group. Hydrocephalus had strong association with severe neurological deficit and seizure with death in both the groups.

CONCLUSION

Several clinical and laboratory features of TBM in patients who are HIV-positive are distinctly different from those without HIV infection; some of these have an association with the probability of adverse outcome.

Stochastic resonance-enhanced laser-based particle detector

This paper presents a Laser-based particle detector whose response was enhanced by modulating the Laser diode with a white-noise generator. A Laser sheet was generated to cast a shadow of the object on a 200 dots per inch, 512 x 1 pixels linear sensor array. The Laser diode was modulated with a white-noise generator to achieve stochastic resonance. The white-noise generator essentially amplified the wide-bandwidth (several hundred MHz) noise produced by a reverse-biased zener diode operating in junction-breakdown mode. The gain in the amplifier in the white-noise generator was set such that the Receiver Operating Characteristics plot provided the best discriminability. A monofiber 40 AWG (approximately 80 microm) wire was detected with approximately 88% True Positive rate and approximately 19% False Positive rate in presence of white-noise modulation and with approximately 71% True Positive rate and approximately 15% False Positive rate in absence of white-noise modulation.

Lattice resistance to dislocation motion at the nanoscale

In this Letter, we propose a model that demonstrates the effect of a free surface on the lattice resistance experienced by a moving dislocation in nanodimensional systems. This effect manifests in an enhanced velocity of dislocation due to the proximity of the dislocation line to the surface. To verify this finding, molecular dynamics simulations for an edge dislocation in bcc molybdenum are performed, and the results are found to be in agreement with the numerical implementations of this model. The reduction in this effect at higher stresses and temperatures, as revealed by the simulations, confirms the role of lattice resistance behind the observed change in the dislocation velocity.

Splenic metastasis and bleeding manifestations--an unusual association with gastric malignancy

Splenic metastasis is a rare clinical entity--incidence being 0.6% at autopsy and 1.1% at splenectomy. We report the case of a 30 year old female who presented with purpura and melena and who was later diagnosed to have a mucinous adenocarcinoma of stomach with disseminated intravascular coagulation and splenic metastasis.

Production of activated carbon from coconut shell: optimization using response surface methodology

The production of activated carbon from coconut shell treated with phosphoric acid (H3PO4) was optimized using the response surface methodology (RSM). Fifteen combinations of the three variables namely; impregnation ratio (1, 1.5, and 2); activation time (10, 20, and 30 min); and activation temperature (400, 450, and 500 degrees C) were optimized based on the responses evaluated (yield, bulk density, average pore diameter, small pore diameter, and number of pores in a unit area). Pore diameters were directly measured from scanning electron microscope (SEM) images. Individual second-order response surface models were developed and contour plots were generated for the optimization analysis. The optimum range identified for impregnation ratio was from 1.345 to 2, while for the activation time was from 14.9 to 23.9 min. For the activation temperature it was from 394 to 416 degrees C. The optimum points are 1.725, 19.5 min, and 416 degrees C, respectively. The models were able to predict well the values of the responses when the optimum variable parameters were validated as proven by the generally acceptable values of the residual percentages. Direct characterization of the pores using the SEM was found to be a good technique to actually see the pores and get actual measurements. Additionally, RSM has also proven to be a good tool in optimization analysis to get not only optimum production condition points but ranges, which are crucial for the flexibility of the production process, as well.

DNA replication and the cell cycle

The replication of DNA in the eukaryotic cell cycle is one of the most highly regulated events in cell growth and division. Biochemical studies on the replication of the genome of the small DNA virus simian virus 40 (SV40) have resulted in the identification of a number of DNA replication proteins from human cells. One of these, Replication Protein A (RPA), was phosphorylated in a cell cycle-dependent manner, beginning at the onset of DNA replication. RPA was phosphorylated in vitro by the cell cycle-regulated cdc2 protein kinase. This kinase also stimulated the unwinding of the SV40 origin of DNA replication during initiation of DNA replication in vitro, suggesting a mechanism by which cdc2 kinase may regulate DNA replication. Functional homologues of the DNA replication factors have been identified in extracts from the yeast Saccharomyces cerevisiae, enabling a genetic characterization of the role of these proteins in the replication of cellular DNA. A cellular origin binding protein had not been characterized. To identify proteins that function like T antigen at cellular origins of DNA replication, we examined the structure of a yeast origin of DNA replication in detail. This origin consists of four separate functional elements, one of which is essential. A multiprotein complex that binds to the essential element has been identified and purified. This protein complex binds to all known cellular origins from S. cerevisiae and may function as an origin recognition complex.