Production of high performance AA7150-1% SiC nanocomposite by novel fabrication process of ultrasonication assisted stir casting.

The effect of ultrasonic vibration treatment on nanoparticle distribution was successfully investigated and developed a novel fabrication process to produce nano silicon carbide particle reinforced AA7150-1% SiC nanocomposite through a combination of the vortex, double stir casting, and ultrasonic vibration techniques. Ultrasonicfrequency of 20 KHz and with a power capacity of 1000 W was used in the process. Ultrasonic probe was used for proper mixing of the nanoparticles in the molten bath. Microstructure investigation of grain formation, particle distribution, and fracture surface was analyzed through an optical and scanning electron microscope at the as-cast condition. Energy dispersive spectroscopy was used for determining chemical composition of the nanocomposite. In the novel fabrication process, the influence of sonication effect on material properties such as porosity, microhardness, tensile strength were examined and compared with double stir casted nanocomposite material as well as the base material. Mechanical properties of AA7150-1% SiC novel fabrication process were enhanced with a reported increase of 26.05% in tensile strength, and 10.85% in microhardness. 74.1% reduction in porosity as compared to the base alloy. In the double stir casting process, there was 19.6% increase in tensile strength, 2.9% of improvement in microhardness, and 46.96% reduction in porosity as compared to base material properties. The enhancement of material properties with the ultrasonic probe assisted novel fabrication process are attributed to grain refinement of composite and homogeneous distribution of SiC nanoparticles due to the acoustic streaming and cavitation effect.

Anti-inflammatory and proapoptotic effects of umbelliferone in colon carcinogenesis.

Colorectal cancer (CRC) is a serious health problem throughout the world. 5-Flurouracil, the first-line chemotherapy of colorectal cancer often produces more toxicity to neighboring cells; however, it is still used for CRC treatment. To overcome this, umbelliferone (UMB), a less toxic bioflavonoid has been used to test its anticancer effects on animal model. The objective of the present study is to evaluate the anticancer activity of UMB on 1,2-dimethylhydrazine (DMH)-induced rat colon tumorigenesis to determine the development of aberrant crypt foci (ACF), agyrophylic nucleolar organizer regions (AgNORs), mast cell recruitment, pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1ß and also study the expressions of inducible nitric oxide synthase, cyclooxygenase (COX)-2, and apoptotic markers. DMH-induced rats showed increased ACF number (incidence), multiplicity and its distribution, counts of AgNORs, mast cells, inflammatory markers and apoptotic proteins. Interestingly, UMB supplementation to DMH-induced rats (group 4) significantly (p < 0.05) suppressed ACF development, AgNORs, mast cells, and inflammatory markers and increased the apoptotic markers as compared to DMH-induced rats (group 2). We concluded that UMB is a potential anticancer agent that can be used for the prevention and treatment of CRC.

Pre-hypertension: Is it an inflammatory state?

Even though several studies have implicated the role of inflammation in the pathogenesis of hypertension and other cardiovascular disease, there are only limited studies about inflammatory markers in prehypertension. The objective of the present article was to review the role of markers like C-reactive protein, interleukin-6, tumor necrosis factor-α and sialic acid in prehypertension. An extensive literature search was made in Pubmed (http://www.ncbi.nlm.nih.gov/pubmed/) using phrases such as prehypertension, inflammation, C-reactive protein, cardiovascular disease, cytokines and sialic acid. Several investigators have reported increased inflammatory markers like C-reactive protein, interleukin-6, tumor necrosis factor-α and sialic acid in prehypertension indicating the role of inflammation in the pathogenesis of prehypertension and its complications. Elevated inflammatory markers may enhance the risk for cardiovascular disease in subjects with prehypertension.

An efficient in vitro system for somatic embryogenesis and podophyllotoxin production in Podophyllum hexandrum Royle.

Podophyllum hexandrum Royle known as Indian mayapple is an important medicinal plant found only in higher altitudes (2,700 to 4,200 m) of the Himalayas. The highly valued anticancer drug Podophyllotoxin is obtained from the roots of this plant. Due to over exploitation, this endemic plant species is on the verge of extinction. In vitro culture for efficient regeneration and the production of podophyllotoxin is an important research priority for this plant. Hence, in the present study, an efficient plant regeneration system for mass multiplication through somatic embryogenesis was developed. We have screened P. hexandrum seeds collected from three different regions in the Himalayas to find their regenerative potentials. These variants showed variation in germination percentage as well as somatic embryogenic frequency. The seeds collected from the Milam area of Pithoragarh district showed better germination response (99.3%) on Murashige and Skoog (MS) medium fortified with Gibberellic acid (GA3 [5 mg/l]) and higher direct somatic embryogenic frequency (89.6%). Maximum production of embryogenic callus (1.2 g fresh weight [FW]) was obtained when cotyledons containing the direct somatic embryo clusters were cultured in MS medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D [1.5 mg/l]) after 4 week of culture in complete darkness. In the present investigation, somatic embryogenesis was accomplished either by direct organogenesis or callus mediated pathways. The latter method resulted in a higher frequency of somatic embryo induction in hormone-free MS medium yielding 47.7 embryos/50 mg of embryogenic callus and subsequent germination in MS medium supplemented with GA3 (5 mg/l). Seventy-nine percent of embryos attained complete maturity and germinated into normal plants with well-developed roots. Systematic histological analysis revealed the origin of somatic embryo and their ontogenesis. The higher level of podophyllotoxin (1.8 mg/g dry weight [DW]) was recorded in germinated somatic embryos when compared to field grown plants. The present system can be widely used for mass propagation, transgenic recovery, and podophyllotoxin production for commercial utilization.

Increased non-enzymatic glycation of plasma proteins and hemoglobin in non-diabetic patients with acute myocardial infarction (MI).

BACKGROUND: Glycation is known to play a key role in complications of many pathophysiological processes. The present study was carried out to assess whether there are abnormalities of non-enzymatic glycation of proteins and hemoglobin in acute Myocardial Infarction (MI) patients. METHODS: Eighteen acute Myocardial Infarction (MI) patients and 20 healthy controls were enrolled for the present study. Fasting plasma glucose, fructosamine, glycated hemoglobin were evaluated. RESULTS: A significant rise in the mean values of fructosamine and glycated hemoglobin was found in acute myocardial patients when compared with controls. When Pearson's correlation analysis was performed, no significant correlation was found between fasting plasma glucose with either fructosamine or glycated hemoglobin levels. CONCLUSION: This data suggests an increased glycation of both plasma proteins and glycated hemoglobin in acute myocardial patients, which might be independent of prevailing glucose concentration.

Artificial humidification for the mechanically ventilated patient.

Caring for patients who are mechanically ventilated poses many challenges for critical care nurses. It is important to humidify the patient's airways artificially to prevent complications such as ventilator-associated pneumonia. There is no gold standard to determine which type of humidification is best for patients who are artificially ventilated. This article provides an overview of commonly used artificial humidification for mechanically ventilated patients and discusses nurses' responsibilities in caring for patients receiving artificial humidification.

Time-varying methods for characterizing nonstationary dynamics of physiological systems.

BACKGROUND: Accurate and early diagnosis of various diseases and pathological conditions require analysis techniques that can capture time-varying (TV) dynamics. In the pursuit of promising TV signal processing methods applicable to real-time clinical monitoring applications, nonstationary spectral techniques are of great significance. OBJECTIVES: We present two potential practical applications of such techniques in quantifying TV physiological dynamics concealed in photoplethysmography (PPG) signals: early detection of blood-volume loss using a nonparametric approach known as variable frequency complex demodulation (VFCDM), and accurate detection of abrupt changes in respiratory rates using a parametric approach known as combined optimal parameter search and multiple mode particle filtering (COPS-MPF). METHODS: The VFCDM technique has been tested using ear-PPG signals in two study models: mechanically ventilated patients undergoing surgery in operating room settings and spontaneously breathing conscious healthy subjects subjected to lower body negative pressure (LBNP) in laboratory settings. Extraction of respiratory rates has been tested using COPS-MPF technique in finger-PPG signals collected from healthy volunteers with abrupt changes in respiratory rate ranging from 0.1 to 0.4 Hz. RESULTS: VFCDM method showed promise to detect the blood loss noninvasively in mechanical ventilated patients well before blood losses become apparent to the physician. In spontaneously breathing subjects during LBNP experiments, the early detection and quantification of blood loss was possible at 40% of LBNP tolerance. COPS-MPF showed high accuracy in detecting the constant as well as sudden changes in respiratory rates as compared to other time-invariant methods. CONCLUSION: Integration of such robust algorithms into pulse oximeter device may have significant impact in real-time clinical monitoring and point-of-care healthcare settings.

Influence of respiratory rate on the variability of blood volume pulse characteristics.

Photoplethysmogram (PPG) measures have been proven useful for the quantification of sympathetic reactivity and continuous monitoring of vascular reactivity. This study was designed to delineate the influence of respiratory rate on the variability of various PPG characteristics in time and frequency domains. PPG, electrocardiogram (ECG) and respiration were simultaneously recorded for 2 min from eight healthy volunteers during paced respiration of 6, 12 and 18 cycles min(-1). The PPG characteristics such as peak-to-peak interval (PPI), systolic peak amplitude, slope, T(crest), T(decay) and pulse transit time (PTT) were computed for every pulse. In time domain, the mean of amplitude, slope and T(crest) were not significantly different amongst three different respiratory rates. However, the mean of T(decay), PPI and PTT were significantly increased (p < 0.05, p < 0.05 and p < 0.01, respectively) during respiration of 6 cycles min(-1) compared to 12 cycles min(-1). The maximal spectral powers of the variability of all PPG measures were centred on the respiratory frequency in frequency domain. In conclusion, the results that the amplitude and slope in time domain are not altered by the respiratory frequency suggest their application in faithful assessment of cardiovascular reactivity. As the variability of PPI, T(decay) and PTT are altered by the slow respiration, the influence of respiration on these time derivatives should not be ignored during interpretation of vascular reactivity.

Protein glycation, insulin sensitivity and pancreatic beta cell function in high-risk, non-diabetic, first degree relatives of patients with type 2 diabetes.

Insulin resistance and impaired beta cell function are widely recognized as features of type 2 diabetes. But it is still debated whether insulin resistance or beta cell dysfunction constitutes the primary abnormality. This study was done to evaluate the impact of family history of type 2 diabetes on insulin resistance, beta cell function and glycation of proteins. A total of 30 healthy subjects with a positive family history of type 2 diabetes and thirty two healthy age-matched subjects without any family history of type 2 diabetes were enrolled in this study. Fasting glucose, post prandial glucose, fasting plasma insulin, fructosamine and glycated hemoglobin were evaluated in both the study groups. The mean fasting glucose, fasting Insulin and HOMA-IR were significantly higher among the first-degree relatives of type 2 diabetics, but there was no alteration in HOMA-B. The levels of both glycated hemoglobin and fructosamine were significantly increased in the test group when compared with controls. In conclusion the results from the present study suggest that Indian subjects with family history of type 2 diabetes are associated with insulin resistance and enhanced glycation of proteins, but with no evidence of beta cell defect.

Assessment of heart rate variability derived from finger-tip photoplethysmography as compared to electrocardiography.

Heart rate variability (HRV) is traditionally derived from RR interval time series of electrocardiography (ECG). Photoplethysmography (PPG) also reflects the cardiac rhythm since the mechanical activity of the heart is coupled to its electrical activity. Thus, theoretically, PPG can be used for determining the interval between successive heartbeats and heart rate variability. However, the PPG wave lags behind the ECG signal by the time required for transmission of pulse wave. In this study, finger-tip PPG and standard lead II ECG were recorded for five minutes from 10 healthy subjects at rest. The results showed a high correlation (median = 0.97) between the ECG-derived RR intervals and PPG-derived peak-to-peak (PP) intervals. PP variability was accurate (0.1 ms) as compared to RR variability. The time domain, frequency domain and Poincaré plot HRV parameters computed using RR interval method and PP interval method showed no significant differences (p < 0.05). The error analysis also showed insignificant differences between the HRV indices obtained by the two methods. Bland-Altman analysis showed high degree of agreement between the two methods for all the parameters of HRV. Thus, HRV can also be reliably estimated from the PPG based PP interval method.

Association between protein bound sialic acid and high sensitivity C-reactive protein in prehypertension: a possible indication of underlying cardiovascular risk.

The global burden posed by cardiovascular disease due to a rising incidence of known risk factors like essential hypertension underlines an urgent need to identify other potential risk factors like dyslipidemia, elevated levels of high-sensitivity CRP (hsCRP), Apo-B, and sialic acid in prehypertensive subjects. This study sought to examine the possible alteration in the levels of hsCRP, plasma protein bound sialic acid, and other lipid risk factors and the possible interactions among these parameters in prehypertensive subjects. Forty prehypertensive and 34 normotensive male subjects were enrolled in the study. Lipid profile, hsCRP, Apo-B, sialic acid, and lipid risk ratios were estimated in both the groups. There was no significant difference between fasting glucose and BMI in either group. The levels of total cholesterol, triglycerides, direct LDL-cholesterol, non-HDL cholesterol, and Apo-B were significantly increased in prehypertensive subjects compared with controls. The risk ratios calculated as direct LDL-cholesterol/Apo-B, total cholesterol/HDL-cholesterol, non-HDL-cholesterol/HDL-cholesterol were significantly elevated in prehypertensive subjects. There was also a significant increase in hsCRP and protein bound sialic acid in prehypertensive subjects in comparison with normotensive subjects. Correlation analysis revealed a significant association between the protein bound sialic acid with hsCRP, LDL cholesterol, and LDL-C/Apo-B. The findings of the present study suggest that in prehypertension, there is an association between protein bound sialic acid and hsCRP that reflects the clustering of cardiovascular risk factors in these subjects.

Is euthyroid sick syndrome a defensive mechanism against oxidative stress?

The body has a hierarchy of defence strategies to deal with oxidative stress. Among these arrays of defence mechanisms, the over expression and increased activity of glutathione peroxidases has been suggested as the first line of defence. The two main cofactors required for glutathione peroxidase activity are selenium and reduced glutathione. These two factors have been shown to be required for the deiodinase activity also. In vitro and in vivo studies have shown that oxidative stress decreases the activity of deiodinase. Thus, a decrease in deiodinase activity would facilitate the use of these cofactors by glutathione peroxidase in combating oxidative stress. Lowering of serum T3 is generally regarded as a valuable calorie-sparing economy. A decreased metabolic state of the cells as found in euthyroid sick syndrome indicates a decreased free radical generation from the mitochondria. For this reason, euthyroid sick syndrome could be considered as a physiological mechanism activated in response to oxidative stress.

Oxidative stress induced changes in plasma protein can be a predictor of imminent severe dengue infection.

OBJECTIVES: Oxidative stress in dengue viral infection has been suggested and severity of it was found to be associated with progress of illness. Hence assessing oxidative stress mediated changes in plasma proteins can be an early biomarker for prediction of severe dengue infection. DESIGN AND METHODS: Thirty two dengue hemorrhagic fever (DHF), 21 dengue shock syndrome (DSS), 27 dengue fever (DF) and 63 age and sex matched controls, were included in this study. Blood samples were collected on the 3rd day of fever. Protein carbonylation (PCOs) and protein-bound sulphydryl (PBSH) group levels were determined by spectrophotometric method and analyzed as predictor of dengue hemorrhagic fever and dengue shock syndrome. RESULTS: About 80-84% of cases presented with no signs of DHF/DSS at the time of sampling. Dengue infected individuals had significantly elevated PCOs and low PBSH group levels than the controls. Using one-way ANOVA we found a significant difference with high PCOs and low PBSH group levels between DHF and DSS when compared with DF (P<0.001). However, no difference was observed in PBSH group levels between DHF and DSS. A significant difference in PCOs to PBSH ratio was observed among DF, DHF and DSS (P<0.001). Linear regression analysis revealed that duration of hospitalization is dependent on PCOs and PBSH group levels. Receiver operator curve (ROC) analysis indicated that 5.22nmol/mg protein PCOs; 1.08 PCOs to PBSH group levels ratio were optimal cutoff value for predicting DHF with sensitivity and specificity of 87.5% and 74.1%; 96.9% and 81.5%, respectively. For DSS prediction, 6.13 nmol/mg protein PCOs; 1.16 PCOs to PBSH group levels ratio were found as effective cutoff with sensitivity and specificity of 81% and 71.9%; 95.2% and 56.2%, respectively. CONCLUSION: Oxidative stress has been observed to develop since early days of onset of dengue infection. Plasma PCOs, PCOs to PBSH group ratio were found to very well predict DHF/DSS.

Altered malondialdehyde, protein carbonyl and sialic acid levels in seminal plasma of microscopically abnormal semen.

Microscopically abnormal (n = 26) semen showed significantly higher levels of malondialdehyde (MDA), protein carbonyl (PC) and protein-bound sialic acid (SA) in seminal plasma as compared with normal semen (n = 24). The percentage of nonmotile spermatozoa showed significant (P < 0.01) positive correlation with MDA (r = 0.5) and PC (r = 0.49). Sperm counts showed a significant negative correlation with MDA (r = -0.63, P < 0.001) level of seminal plasma. SA correlated (r = 0.56, P < 0.01) with MDA. The receiver operating characteristic (ROC) curve of MDA and SA showed that MDA of 3.15 micromol l(-1) and SA of 3.85 micromol l(-1) were optimum cut-off limits to discriminate abnormal semen from normal. In conclusion, high SA might be a protective response against prevailed oxidative stress in abnormal semen. Seminal plasma MDA and SA may act as potential markers of abnormal semen.

Bitter gourd (Momordica charantia) improves insulin sensitivity by increasing skeletal muscle insulin-stimulated IRS-1 tyrosine phosphorylation in high-fat-fed rats.

The aim of this present study was to investigate the effect of bitter gourd extract on insulin sensitivity and proximal insulin signalling pathways in high-fat-fed rats. High-fat feeding of male Wistar rats for 10 weeks decreased the glucose tolerance and insulin sensitivity compared to chow-fed control rats. Bitter gourd extract supplementation for 2 weeks (9th and 10th) of high-fat feeding improved the glucose tolerance and insulin sensitivity. In addition bitter gourd extract reduced the fasting insulin (43 (se 4.4) v. 23 (se 5.2) microU/ml, P < 0.05), TAG (134 (se 12) v. 96 (se 5.5) mg/dl, P < 0.05), cholesterol (97 (se 6.3) v. 72 (se 5.2) mg/dl, P < 0.05) and epidydimal fat (4.8 (se 0.29) v. 3.6 (se 0.24) g, P < 0.05), which were increased by high-fat diet (HFD). High-fat feeding and bitter gourd supplementation did not have any effect on skeletal muscle insulin receptor, insulin receptor subtrate-1 (IRS-1) and insulin- stimulated insulin receptor tyrosine phosphorylation compared to chow-fed control rats. However high-fat feeding for 10 weeks reduced the insulin-stimulated IRS-1 tyrosine phosphorylation compared to control rats. Bitter gourd supplementation together with HFD for 2 weeks improved the insulin-stimulated IRS-1 tyrosine phosphorylation compared to rats fed with HFD alone. Our results show that bitter gourd extract improves insulin sensitivity, glucose tolerance and insulin signalling in HFD-induced insulin resistance. Identification of potential mechanism(s) by which bitter gourd improves insulin sensitivity and insulin signalling in high-fat-fed rats may open new therapeutic targets for the treatment of obesity/dyslipidemia-induced insulin resistance.

Oxidative stress: does it play a role in the genesis of early glycated proteins?

Glycation and oxidative stress are two important processes known to play a key role in complications of many pathophysiological processes. The two traditional factors found to modulate the early glycation of proteins are the prevailing concentration of glucose and half life of the protein. But evidences in the literature have documented an increased glycated protein levels in some non-diabetic pathological states. So it stands to reason that hyperglycemia, while clearly the culprit in diabetes, is not the complete answer to the etiology of increased early glycated products in non-diabetic conditions. A common denominator in all these above mentioned non-diabetic pathological conditions is oxidative stress. Collective evidences from the literature reveal that malondialdehyde, reduced glutathione, vitamin C, vitamin E and drugs with antioxidant properties mitigate the process of protein glycation. Taking all the above factors into account, we hypothesis that oxidative stress either via increasing reactive oxygen species or by depleting the antioxidants may modulate the genesis of early glycated proteins in vivo.

Increased plasma malondialdehyde and fructosamine in iron deficiency anemia: effect of treatment.

Glycation and lipid peroxidation are spontaneous reactions that are believed to play a key role in the pathogenesis of many clinical disorders. Glycation of proteins is enhanced by elevated glucose concentrations. However, increased glycated hemoglobin levels have been documented in iron deficiency anemic patients without any history of diabetes. Collective evidences reveal that lipid peroxidation can modulate protein glycation. This study was undertaken to unravel the possible association of malondialdehyde and fructosamine in iron deficient anemic patients and to observe the possible alteration in malondialdehyde and fructosamine levels in these patients after one month supplementation with iron. Twenty non-diabetic anemic patients and 16 age-matched healthy subjects were enrolled for this study. Plasma lipid peroxides, fasting glucose, fructosamine, iron, ferritin and hemoglobin were analyzed in both the groups. Partial correlation analysis was performed to predict the independent association of malondialdehyde and fasting glucose on fructosamine. In anemic patients, while fructosamine and malondialdehyde levels were found to be significantly increased, hemoglobin, iron and ferritin levels decreased significantly when compared to before treatment. Fructosamine was found to have a significant positive correlation with malondialdehyde even after nullifying the effect of glucose. After one month supplementation with iron, both fructosamine and malondialdehyde levels decreased significantly when compared to before treatment. There was a significant increase in iron, ferritin and hemoglobin levels in anemic patients after one month of treatment. In conclusion, an increased level of fructosamine and malondialdehyde was found in anemic patients. These data suggest that fructosamine levels are closely associated with malondialdehyde concentrations in iron deficient anemic patients.

Altered oxidant-antioxidant status in non-obese men with moderate essential hypertension.

BACKGROUND: Although a wide number of experimental evidences are available regarding oxidant-antioxidant disturbance in hypertension, clinical data supporting it is lacking in men in early stages of hypertension. AIMS: The objective of the study was to evaluate oxidative status and antioxidant activities in males with stage I essential hypertension. MATERIALS AND METHODS: Thirty hypertensives and 21 normotensives were included in the study. Protein carbonyl, reduced glutathione, glutathione peroxidase, catalase and fasting glucose were assessed in both the groups. STATISTICAL ANALYSIS: Results were analyzed by student's 't' test and linear regression analysis test. RESULTS: Plasma protein carbonyl and glutathione peroxidase were significantly increased and catalase and GSH were significantly reduced in the hypertensive group compared to normotensive subjects. There was a significant negative correlation between glutathione peroxidase and catalase in the test group. CONCLUSIONS: The data from the present study indicates an alteration in oxidant-antioxidant status in non-obese men in early stages of essential hypertension.