Reduction of perifusate magnesium alters inotropic response of papillary muscle to ion channel modulators.

Magnesium has a significant role in the regulation of ion transport. Marginal deficiency of Mg can therefore affect myocardial excitability and contractility. This study was taken up with the objective of examining the inotropic response of the myocardium to variation in extracellular [Mg]o and identifying the ion channels and pumps mediating the inotropic changes. Electrically stimulated rat papillary muscle was used as the experimental model and mechanical changes were recorded using a physiograph. Channel specific antagonists were used to identify the channels mediating the functional changes. Diastolic Ca2+ levels were determined in isolated myocytes by the ratiometric method using the fluorescent indicator Fura2-AM. A negative association was observed between the level of [Mg]o and force of contraction, with a peak at 0.48 mM Mg. The force of contraction in Mg deficient medium (0.48 mM) was 158% of control (1.2 mM Mg) (p < 0.001). Inotropic response to the L-type channel antagonist (verapamil-1 microm) and NaK ATPase inhibitor (Ouabain-0.3 mM) was augmented in Mg deficiency (p < 0.005), indicating activation of the channel and the pump. The response to T-type channel inhibitor (NiCl2-40 microM) was attenuated in Mg deficiency (p < 0.05). The response to the sarcoplasmic reticular Ca pump inhibitor (caffeine-10 mM) and the SR Ca2+ release channel inhibitor (ryanodine-1 microM) were not significantly affected by Mg deficiency. Diastolic level of Ca2+ increased with a decrease in Mg (p < 0.05). The observations of the study lead to the conclusion that the positive inotropic response in Mg deficiency is mediated by an increase in basal Ca2+ combined with Ca-induced-Ca release consequent to Ca2+ influx through L-type Ca channel. Variation in sensitivity to Ca channel blockers and NaK ATPase inhibitor in Mg deficiency can have pharmacological implications.     

TYPE IVa CHOLEDOCHAL CYSTS: SURGICAL MANAGEMENT AND LITERATURE REVIEW

Type IVa choledochal cysts with cylindrical dilatation of the intrahepatic ducts constitute a relatively less recognized variety of choledochal cysts, and differ from cystic dilatation of intrahepatic ducts in their clinical manifestations and response to treatment. Five patients with type IVa choledochal cysts and cylindrical dilatation of major intrahepatic ducts who underwent cyst excision and Roux-en-Y hepaticojejunostomy are reported. The duration of symptoms was less than 1 year in all patients. Palpable abdominal mass and abdominal pain were present in 3 patients. The triad of jaundice, abdominal pain and mass was present in only 1 patient. The intrahepatic dilatation regressed after excision of the extrahepatic cyst just below the hilum of the liver. The surgical technique is described and the need for excision of the cyst is emphasized.     

Bacterial meningitis vaccines: Not just for kids

Bacterial meningitis remains a feared diagnosis that may lead to significant mortality and morbidity in both the developed and developing world; case fatality rates range from 10% to 50% among all age groups. Several vaccines are available (including the Haemophilus influenzae type B polysaccharide conjugate vaccine) that have proven effective in reducing the incidence of bacterial meningitis. Although a 23-valent pneumococcal polysaccharide vaccine has been available for some time, use of the 7-valent pneumococcal conjugate vaccine (PCV) has demonstrated a dramatic reduction in the incidence of invasive pneumococcal disease; despite the increase in the disease caused by nonvaccine-serotype strains, the success of the 7-valent PCV is noteworthy. A quadrivalent conjugate meningococcal vaccine has been available in the United States since 2005; although its true efficacy remains to be determined, there have been dramatic results with declining incidence in certain high-risk populations and in endemic areas.     

Linear Models of Cumulative Distribution Function for Content-based Medical Image Retrieval

We propose an Image matching technique based on Cumulative Distribution Function, which provides a considerable reduction in the retrieval time. The two novel approaches called bit plane histogram and hierarchical bit plane histogram are discussed. Next, the image matching technique based on Cumulative Distribution Function is explained and a comparison of the various techniques is brought out. The CDF of the query and the images in the database are approximated by piecewise linear models with two parameters, slope and intercept at various grayscale intervals. The contiguous set of lines approximating the CDFs enables us to compare the query image and the images in the database with corresponding estimated slopes and intercepts. As the dynamic range of CDF is from 0 to 1, images of different sizes can be compared. Approximation of CDFs with lines further reduces the dimension of the image features and thus improves the speed of matching.     

Effect of luminal acidification on guinea pig gastric mucosa

H⁺ secretion was studied in guinea pig fundic mucosa incubated in (A) bicarbonate-Ringer's gassed with 95% O₂-5% CO₂, or (B) HEPES gassed with 100% O₂ before and after luminal pH was lowered to 2.0 for periods up to 90 min. At pH 2.0 for 60 min, H⁺ secretion in group A tissues fell by 35±4% (P=0.02) from a control rate of 1.35±0.09 eq/cm²/hr and in group B tissues by 50±11% (P=0.01) from a control rate of 1.59±0.08 eq/cm²/hr. After 90 min at pH 2.0, H⁺ secretion in group A fell by 53±8% (P=0.02) from a control rate of 1.47±0.07 eq/cm²/hr and in group B fell by 44±6% (P=0.01) from a control rate of 1.38±0.07 eq/cm²/hr. Histamine 1×10^–4 M stimulation following exposure to pH 2.0 for 90 min increased secretion in group A tissues from 0.80 ±0.14 to 1.06±0.13 eq/cm²/hr (P<0.05), compared with an increase in nonacidified controls from 1.15±0.22 to 1.80±0.20 eq/cm²/hr (P<0.05) and in group B tissues from 1.27±0.10 to 1.56±0.19 eq/cm²/hr (P<0.05) compared with nonacidified controls from 1.43±0.22 to 2.23±0.41 eq/cm²/hr (P<0.05). Secretory function and electrical characteristics were adversely affected by luminal acidification to pH 2.0 and suggested a breach in the mucosal barrier with damage to parietal cells.This study was funded by the National Institute of Health Grant No. AM 15681.     

Mint leaf derived carbon dots for dual analyte detection of Fe(iii) and ascorbic acid

Highly luminescent carbon dots (CDs) are obtained from mint leaves adopting a simple and cost effective route devoid of additional chemical reagents and functionalization. The as-synthesized CDs are characterized by TEM, FE-SEM, XRD analysis, FTIR, Raman, UV-visible and photoluminescence spectral studies. The results reveal that the CDs have an average diameter of 4 nm with a hydroxyl-rich surface. The luminescence of the dots was excitation dependent and was stable towards variation in the medium. The system could perform as a promising on–off–on fluorescent sensor for the selective and sensitive dual analyte recognition of Fe³⁺ and AA with a detection limit of 374 nM and 79 nM, respectively. The mechanism of ascorbic acid sensing by the CD–Fe³⁺ unit is established by identifying the binding sites of the biomolecule with the metal ion by examining the behaviour of the sensor in the presence of ascorbic acid derivatives.

Highly luminescent carbon dots (CDs) are obtained from mint leaves adopting a simple and cost effective route devoid of additional chemical reagents and functionalization.