Sensitive and rapid titrimetric and spectrophotometric methods for the determination of stavudine in pharmaceuticals using bromate-bromide and three dyes

Four sensitive and rapid methods for the determination of stavudine (STV) in bulk drug and in dosage forms were developed and optimized. In titrimetry, aqueous solution of STV was treated with a known excess of bromate-bromide in HCl medium followed by estimation of unreacted bromine by iodometric back titration. Spectrophotometric methods involve the addition of a measured excess of bromate-bromide in HCl medium and subsequent estimation of the residual bromine by reacting with a fixed amount of methyl orange, indigocarmine or thymol blue followed by measurement of absorbance at 520 nm (method A), 610 nm (method B) or 550 nm (method C). In all the methods, the amount of bromate reacted corresponds to the amount of STV. Calculations in titrimetry were based on a 1:0.666 (STV:KBrO3) stoichiometry and the method was found to be applicable over 3.5-10 mg range. A linear increase in absorbance with concentration of STV was observed in the spectrophotometric methods, and the Beer's law was obeyed over the concentration ranges 0.125-1.75, 1-10 and 1-9.0 microg mL-1 STV for method A, method B and method C, respectively. The methods when applied to the determination of STV in tablets and capsules were found to give satisfactory results.     

The Transseptal T‐Cut—What More Can We See?

Abstract   An optimal approach to the mitral valve for repair or replacement must provide adequate exposure even in a small left atrial and redo cases, without need for forceful retraction. This benefit of good exposure must not be at the cost of increased morbidity from increased postoperative bleeding, SA node, or atrioventricular node dysfunction. We describe a simple technique of transseptal T-cut for exposure of the mitral valve, which is without the attendant complications of the other techniques.     

GP attitudes to managing drug- and alcohol-dependent patients: a reluctant role

The aim of this study was to determine the experience, confidence and views of GPs in South West Sydney towards managing drug and alcohol dependence and their interest in participating in shared care methadone prescribing. Five hundred and forty-eight GPs were mailed a self complete questionnaire. Non-responders were followed-up by telephone. Seventy-six per cent of GPs responded; 52% considered methadone maintenance to be effective. GPs were more confident managing smoking than alcohol and benzodiazepine dependence and least confident in illicit drug dependence. Fifty per cent reported having no patients on methadone and 40% between one and five patients. GPs in Fairfield and Liverpool reported having most patients; 25% were interested in prescribing methadone for patients in their own practice and 17% for patients referred to them. GPs who had more patients on methadone in their practice (especially those in Fairfield and Liverpool) considered methadone effective and were more likely to be interested in having patients referred to them. The most frequent reasons for not being interested were concerns about patients being demanding or aggressive or the impact on their practice. The most frequently requested support for shared care prescribing was for 24-hour back-up from specialist services, especially requested by those with less experience with patients on methadone. A shared-care approach to facilitating greater GP involvement in prescribing appears feasible, especially among GPs with some previous experience with patients on methadone.     

Nanobiomaterial applications in orthopedics.

Advancements in nanobiotechnology are revolutionizing our capability to understand biological intricacies and resolve biological and medical problems by developing subtle biomimetic techniques. Nanocomposites and nanostructured materials are believed to play a pivotal role in orthopedic research since bone itself is a typical example of a nanocomposite. This article reviews current strategies using nanobiomaterials to improve current orthopedic materials and examines their applications in bone tissue engineering. Preliminary investigations support the potential of nanobiomaterials in orthopedic applications; however, significant advancements are necessary to achieve clinical use. Overall, current trends in nanobiotechnology foreshadow a bright future through the use of nanobiomaterials in the orthopedic domain.     

Optimization of culture conditions for the preservation of monkey pancreatic islets in culture.

Culturing of islets is essential for various purposes before transplantation. It is necessary to establish optimal culture conditions for each animal species for their preservation in culture. In this study, attempts were made to preserve the Indian bonnet monkey islets in culture. The islets were isolated from monkey pancreas by the collagenase digestion method. They were separated from acinar cells by dextran density-gradient centrifugation. They were preserved in a humidified atmosphere of 5% carbon dioxide and 95% air for 7 days. The culture medium used was RPMI-1640. Various optimal conditions such as volume of the culture medium used, number of islets in one culture dish, concentration of glucose in culture medium, and fetal calf serum percentage were tested for their better preservation in culture. After the culture period, they were tested for their insulin secretory capacity by exposing them to various secretagogues. Histologic appearance of the cultured islets also was examined. Both insulin secretory characteristics and histologic structure were found to be normal.     

Liver histology and immunohistochemical findings in asymptomatic Indians with incidental detection of hepatitis B virus infection.

BACKGROUND AND OBJECTIVES: The relationship between hepatocyte expression of hepatitis B virus (HBV) antigens, liver histology and viral replication in asymptomatic subjects with incidental detection of hepatitis B surface antigen (HBsAg) remains unclear. We evaluated the histological activity index (HAI) and hepatocyte expression of viral antigens with replicative status in asymptomatic chronic HBV infection. METHODS: Asymptomatic subjects with incidental detection of HBsAg and ALT levels less than twice the upper limit of normal were grouped as follows: Group A - negative for HBeAg and HBV DNA (no HBV replication); B - HBeAg negative, HBV DNA positive (low HBV replication or pre-core mutant); C - positive HBeAg and HBV DNA (high viral replication). Liver biopsies were assessed for HAI (Ishak's scoring system). These were also subjected to immunohistochemistry for expression of HBsAg and hepatitis B core antigen (HBcAg); distribution, staining pattern and quantitative measurement of antigen expression were assessed. RESULTS: Median HAI was similar in the three groups (1.0, 2.0 and 2.0 in groups A, B and C, respectively). All subjects in Group C showed discrete cytoplasmic expression of HBsAg, whereas the other two groups showed heterogeneity in distribution and pattern of HBsAg staining. Quantitative measurement of cytoplasmic HBsAg revealed similar results in the three groups. Core antigen (nuclear) was detected in 4 of 5 subjects in Group C and none of those in Groups A and B. Ground-glass hepatocytes were seen in 20 and orcein-positive cells in 26 cases. HBsAg was detected by immunohistochemistry in 37 biopsies. CONCLUSIONS: Among asymptomatic subjects with chronic HBV infection, those with high rate of viral replication had discrete cytoplasmic HBsAg expression and nuclear expression of core antigen; these findings were uncommon in subjects with low or no viral replication.