Microscopic theory of longitudinal sound velocity in charge ordered manganites

A microscopic theory of longitudinal sound velocity in a manganite system is reported here. The manganite system is described by a model Hamiltonian consisting of charge density wave (CDW) interaction in the e(g) band, an exchange interaction between spins of the itinerant e(g) band electrons and the core t(2g) electrons, and the Heisenberg interaction of the core level spins. The magnetization and the CDW order parameters are considered within mean-field approximations. The phonon Green's function was calculated by Zubarev's technique and hence the longitudinal velocity of sound was finally calculated for the manganite system. The results show that the elastic spring involved in the velocity of sound exhibits strong stiffening in the CDW phase with a decrease in temperature as observed in experiments.

Injection drug use in Calcutta: a potential focus for an explosive HIV epidemic

Our objective was to assess HIV risk perceptions, risk behaviours and factors that may facilitate an increase in injection drug use in Calcutta. Focus group discussions and in-depth interviews were conducted with a selected group of drug users to delineate drug use patterns, languages used to express addictive and related experiences and acceptance of harm minimization messages. Results from these were used to develop a semi-structured interview instrument which was used to interview 111 drug users (76 IDUs and 35 non-IDUs) recruited from jails and detoxification centres. Secondary data of narcotic seizures for the last 5 years were collected from the Calcutta police department. Data on percentage of IDUs admitted to large detox facility in the city was also collected. Findings show that HIV/AIDS knowledge and risk perceptions were low; sharing of injection equipment was reported by 66% of the injectors; and condom use was insignificant. Non-availability, rising cost and increasing tolerance to heroin were cited as factors contributing to switch to injection. Ecological association was found between intensified police activity and an increase in: the amount of smokable heroin seized; increased injection of buprenorphine; and admission to detoxification centres. In addition to HIV, IDUs were also found to be prone to hepatitis B and C. The findings suggest an urgent need for developing and implementing community-based HIV prevention interventions targeting drug users in Calcutta.

Thyroid inhibitory, antiperoxidative and hypoglycemic effects of stigmasterol isolated from Butea monosperma

Stigmasterol, isolated from the bark of Butea monosperma was evaluated for its thyroid hormone and glucose regulatory efficacy in mice. Its administration at 2.6 mg/kg/d for 20 days reduced serum triiodothyronine (T(3)), thyroxin (T(4)) and glucose concentrations as well as the activity of hepatic glucose-6-phophatase (G-6-Pase) with a concomitant increase in insulin indicating its thyroid inhibiting and hypoglycemic properties. A decrease in the hepatic lipid peroxidation (LPO) and an increase in the activities of catalase (CAT), superoxide dismutase (SOD) and glutathione (GSH) suggested its antioxidative potential. The highest concentration tested (5.2 mg/kg) evoked pro-oxidative activity.

Acoustic backscatter and effective scatterer size estimates using a 2D CMUT transducer

Compared to conventional piezoelectric transducers, new capacitive microfabricated ultrasonic transducer (CMUT) technology is expected to offer a broader bandwidth, higher resolution and advanced 3D/4D imaging inherent in a 2D array. For ultrasound scatterer size imaging, a broader frequency range provides more information on frequency-dependent backscatter, and therefore, generally more accurate size estimates. Elevational compounding, which can significantly reduce the large statistical fluctuations associated with parametric imaging, becomes readily available with a 2D array. In this work, we show phantom and in vivo breast tumor scatterer size image results using a prototype 2D CMUT transducer (9 MHz center frequency) attached to a clinical scanner. A uniform phantom with two 1 cm diameter spherical inclusions of slightly smaller scatterer size was submerged in oil and scanned by both the 2D CMUT and a conventional piezoelectric linear array transducer. The attenuation and scatterer sizes of the sample were estimated using a reference phantom method. RF correlation analysis was performed using the data acquired by both transducers. The 2D CMUT results indicate that at a 2 cm depth (near the transmit focus for both transducers) the correlation coefficient reduced to less than 1/e for 0.2 mm lateral or 0.25 mm elevational separation between acoustic scanlines. For the conventional array this level of decorrelation requires a 0.3 mm lateral or 0.75 mm elevational translation. Angular and/or elevational compounding is used to reduce the variance of scatterer size estimates. The 2D array transducer acquired RF signals from 140 planes over a 2.8 cm elevational direction. If no elevational compounding is used, the fractional standard deviation of the size estimates is about 12% of the mean size estimate for both the spherical inclusion and the background. Elevational compounding of 11 adjacent planes reduces it to 7% for both media. Using an experimentally estimated attenuation of 0.6 dB cm(-1) MHz(-1), scatterer size estimates for an in vivo breast tumor also demonstrate improvements using elevational compounding with data from the 2D CMUT transducer.

Plasma MDA and antioxidant vitamins in diabetic retinopathy

Hyperglycemia and dyslipidemia in diabetes mellitus induce increased lipid peroxidation and peroxyl radical formation, an important mechanism in genesis of microangiopathy. We took up a study on oxidative stress, measured by plasma MDA and antioxidant vitamin status in type - 2 DM patients with and without retinopathy and compared them with a control non-diabetic group. Lipid peroxidation marker MDA was significantly elevated (p < 0.001) in both the diabetic groups whereas, serum vitamin E and vitamin C registered a significant fall (p<0.001) as compared to controls. Our correlation study revealed a significant positive association between plasma MDA with both fasting and 2hr post prandial plasma glucose (r=0.81, p < 0.001, r=0.92, p <0.001) suggesting the role of hyperglycemia in free radical production. Plasma MDA also depicted significant positive relation (p< 0.001) with all lipid parameters except serum HDLc pointing the role of dyslipidemia towards lipid peroxidation. Plasma MDA level was also found to be negatively correlated with both the vitamins (p<0.001, p<0.001) in the study group explaining their protective consumption in the oxidative process prevailing in diabetic retinopathy.

Cholesterol ester storage disease with unusual neurological manifestations in two siblings: a report from South India

Cholesterol ester storage disease is a rare autosomal recessive storage disorder resulting from lysosomal acid lipase deficiency. Two siblings manifested with hepatosplenomegaly, ptosis, and bilateral external ophthalmoplegia. Evaluation revealed hyperlipidemia and bilateral adrenal calcifications. Leukocyte acid lipase levels were significantly low in both the patients, compared with controls, suggesting a diagnosis of cholesterol ester storage disease. Ptosis and external ophthalmoplegia have hitherto not been reported in cholesterol ester storage disease.

Annona squamosa seed extract in the regulation of hyperthyroidism and lipid-peroxidation in mice: possible involvement of quercetin

Annona squamosa (Custard apple) seeds are generally thrown away as waste materials. The extract of these seeds was evaluated for its possible ameliorative effect in the regulation of hyperthyroidism in mouse model. Serum triiodothyronine (T(3)), thyroxine (T(4)) concentrations, hepatic glucose-6-phospatase (G-6-Pase) and 5'-mono-deiodinase (5'DI) activity were considered as the end parameters of thyroid function. Simultaneously hepatic lipid peroxidation (LPO), superoxide dismutase (SOD) and catalase (CAT) activities were investigated to observe its hepatotoxic effect, if any. L-T(4) administration (0.5 mg/kg/d for 12 days, i.p.) increased the levels of serum T(3) and T(4), activity of hepatic G-6-Pase, 5'DI and LPO with a parallel decrease in SOD and CAT activities. However, simultaneous administration of the Annona seed extract (200 mg/kg) or quercetin (10 mg/kg) to T(4)-induced hyperthyroid animals for 10 days, reversed all these effects indicating their potential in the regulation of hyperthyroidism. Further, the seed extract did not increase, but decreased the hepatic LPO suggesting its safe and antiperoxidative nature. Quercetin also decreased hepatic LPO. When relative efficacy was compared with that of propyl thiouracil (PTU), a standard antithyroidic drug, experimental seed extract appeared to be more effective. Phytochemical analyses including HPLC revealed the presence of quercetin in the seed extract and the results on the effects of quercetin suggested the involvement of this phytochemical in the mediation of antithyroidal activity of Annona squamosa seed extract.

Surgical techniques: robotic bladder diverticulectomy with the da Vinci-S surgical system

Bladder diverticulectomy is a surgical operation for symptomatic or large bladder diverticula. Typically, bladder diverticula are because of infravesical obstruction, although congenital diverticula can occur that may be large and symptomatic. The ability to excise the diverticulum completely, avoid important adjacent structures, and close the bladder defect in a watertight fashion are key fundamentals to this operation. Traditionally done via an open extravesical, intravesical, or combined approach, bladder diverticulectomy can now be done in a minimally invasive fashion. Both laparoscopic and robot-assisted methods have clear advantages over open surgery, including smaller incision, reduced pain, improved cosmesis, and reduced blood loss, with an equivalent functional result. Large bladder diverticula, particularly those involving the ureteric orifice which required ureteric reimplantation, were often considered beyond the scope of conventional laparoscopy. Recently, use of robotic technology as a means of facilitating laparoscopic excision of bladder diverticula has provided the ability to treat large and more complex diverticula. Advantages of the robotic approach are the finer precision and dexterity of the instruments coupled with three-dimensional imaging. Although there are several case reports describing pure laparoscopic diverticulectomy, as far as we are aware there are no published reports of robotic bladder diverticulectomy. This paper will outline a safe and reproducible surgical technique for performing robotic bladder diverticulectomy using the da Vinci-S surgical system.

Role of a novel photopigment, melanopsin, in behavioral adaptation to light

Adaptation to changes in the ambient light is of critical importance to life. In mammals, three principal photoadaptation mechanisms depend on ocular photoreception and exhibit spectral sensitivity suggestive of the opsin class of photopigment(s). These include rapid adaptation of the visual system to the ambient light by pupil constriction, direct modulation of neuroendocrine function and entrainment of the circadian clock to the day:night cycle. Surprisingly, these processes can largely function independent of classical rod/cone photoreceptors, suggesting a novel opsin-based signaling mechanism. They appear to involve a recently discovered network of intrinsically photosensitive retinal ganglion cells that make direct or indirect axonal connections to brain centers regulating photoadaptive behaviors. The discovery of a novel opsin, melanopsin, in these cells has offered an exciting entry point to explore, at the molecular level, how mammals adapt to their light environment. There is now genetic proof of a principal role for melanopsin in all three major photoadaptation processes.

Cardio-protective role of Terminalia arjuna bark extract is possibly mediated through alterations in thyroid hormones

Terminalia arjuna bark extract is believed to exhibit cardio-protective effects. In the present study we investigated the possible involvement of thyroid hormones in the amelioration of cardiac and hepatic lipid peroxidation (LPO) by a bark extract of the plant in albino rats. While L-thyroxine (L-T4) treatment increased the level of thyroid hormones, heart/body weight ratio as well as cardiac and hepatic lipid peroxidation, simultaneous administration of 21.42 and 42.84 mg/kg of the plant extract decreased the level of thyroid hormones and also the cardiac LPO, suggesting the possible mediation of the drug action through an inhibition in thyroid function. These effects were comparable to a standard antithyroid drug, propyl thiouracil (PTU). When the drug was administered to euthyroid animals, serum concentrations of thyroid hormones were decreased, whereas the hepatic LPO increased indicating a drug induced toxicity in euthyroid subjects. Although a suboptimal dose of the drug was found to be non-toxic to the liver, it appeared to be of no use, as it could neither affect the thyroid functions nor the cardiac lipid peroxidation. Since in euthyroid animals, thyroid hormones were decreased and hepatic LPO was increased, it is suggested that high amounts of this plant extract should not be consumed, as hepatotoxicity as well as hypothyroidism may be caused.

Recruitment of governing elements for electron transfer in the nitric oxide synthase family

At least three building blocks are responsible for the molecular basis of the modulation of electron transfer in nitric oxide synthase (NOS) isoforms: the calmodulin-binding sequence, the C-terminal extension, and the autoregulatory loop in the reductase domain. We have attempted to impart the control conferred by the C termini of NOS to cytochrome P450 oxidoreductase (CYPOR), which contains none of these regulatory elements. The effect of these C termini on the properties of CYPOR sheds light on the possible evolutionary origin of NOS and addresses the recruitment of new peptides on the development of new functions for CYPOR. The C termini of NOSs modulate flavoprotein-mediated electron transfer to various electron acceptors. The reduction of the artificial electron acceptors cytochrome c, 2,6-dichlorophenolindophenol, and ferricyanide was inhibited by the addition of any of these C termini to CYPOR, whereas the reduction of molecular O(2) was increased. This suggests a shift in the rate-limiting step, indicating that the NOS C termini interrupt electron flux between flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) and/or the electron acceptors. The modulation of CYPOR by the addition of the NOS C termini is also supported by flavin reoxidation and fluorescence-quenching studies and antibody recognition of the C-terminal extension. These experiments support the origin of the NOS enzymes from modules consisting of a heme domain and CYPOR or ferredoxin-NADP(+) reductase- and flavodoxin-like subdomains that constitute CYPOR, followed by further recruitment of smaller modulating elements into the flavin-binding domains.

Myasthenic crisis: a retrospective study

BACKGROUND AND OBJECTIVE

Myasthenic crisis (MC) is one of the important and common complications in the natural history of myasthenia gravis (MG). MC can be precipitated by multiple factors including deficiency or excess of the acetylcholinesterase inhibitors (AChEI). Any episode of MC is an emergency requiring aggressive therapy. We studied the demographic, clinical and treatment-related characteristics of patients who developed MC.

MATERIALS AND METHODS

A retrospective study was conducted in patients with MC admitted during a 31-month period from February 1999 to August 2001, at a tertiary care center in India.

RESULTS

Eleven patients (9.69% of the total 114 patients with MG) were admitted with 12 episodes of MC. Mean age at presentation was 39.83 + 13.18 years with male predominance. Seven patients had undergone thymectomy previously; of which 2 had postoperative MC. Six patients had thymoma. Steroid or cholinesterase inhibitor withdrawal and infections were the commonest precipitating factors for MC. Patients required ventilatory support for median 14 days. They responded to low volume of plasma exchange (PE) (mean 854 ml / day with mean 6.5 cycles per patient).

CONCLUSIONS

This report highlights that the subset of Indian patients with MG who are at risk to develop MC belong to the 3rd and 4th decade, have bulbar symptoms at presentation and are associated with thymoma. Patients with MC should have judicious drug adjustments under supervision and should be treated aggressively during impending MC.

Fruit extract of Emblica officinalis ameliorates hyperthyroidism and hepatic lipid peroxidation in mice

The ethanolic extract from the fruits of Emblica officinalis Gaertn (Euphorbiaceae) was investigated to evaluate its possible ameliorating effects, on the L-thyroxine (L-T4) induced hyperthyroidism and on hepatic lipid peroxidation in mice. While an increase in serum T3 (triiodothyronine) and T4 (thyroxine) concentrations, and in a thyroid dependent parameter, hepatic glucose 6-phospatase (glu-6-pase) activity was observed in L-T4 (0.5 mg/kg/d) treated animals, simultaneous oral administration of the plant extract at a dose of 250 mg/kg/d (p.o.) for 30 days in hyperthyroid mice reduced T3 and T4 concentrations by 64 and 70% respectively as compared to a standard antithyroid drug, propyl thiouracil (PTU) that decreased the levels of the thyroid hormones by 59 and 40% respectively. The plant extract also maintained nearly normal value of glu-6-pase activity in hyperthyroid mice. The plant extract also decreased hepatic lipid peroxidation (LPO) and increased the superoxide dismutase (SOD) and catalase (CAT) activities in hyperthyroid mice, exhibiting its hepatoprotective nature. Our findings suggest that the test material may potentially ameliorate the hyperthyroidism with an additional hepatoprotective benefit.

Piperine lowers the serum concentrations of thyroid hormones, glucose and hepatic 5'D activity in adult male mice

Piperine, the main alkaloid of Piper nigrum fruits, was evaluated for its thyroid hormone and glucose regulatory efficacy in adult male Swiss albino mice. Its daily oral administration (2.50 mg/kg) for 15 days lowered the serum levels of both the thyroid hormones, thyroxin (T (4)) and triiodothyronine (T (3)) as well as glucose concentrations with a concomitant decrease in hepatic 5'D enzyme and glucose-6-phospatase (G-6-Pase) activity. However, no significant alterations were observed in animals treated with 0.25 mg/kg of piperine in any of the activities studied except an inhibition in serum T (3) concentration. The decrease in T (4), T (3) concentrations and in G-6-Pase were comparable to that of a standard antithyroid drug, Proylthiouracil (PTU). The hepatic lipid-peroxidation (LPO) and the activity of endogenous antioxidants, superoxide dismutase (SOD), and catalase (CAT) were not significantly altered in either of the doses. It appears that the action of P. nigrum on thyroid functions is mediated through its active alkaloid, piperine. We also suggest that a higher dose of piperine may inhibit thyroid function and serum glucose concentration in euthyroid individuals.

X-linked lissencephaly in an Indian family

Neuronal migration disorders are an important differential diagnosis to be considered in the evaluation of intractable epilepsy. Though the underlying causative factors which govern their development are many and varied, genetic factors have been found to be contributory in a few forms of these disorders. An X-linked association with lissencephaly has recently been discovered and there are a few families described till now with this entity.