Prediction of the impact of lubrication on tablet compactibility

The tableting of most pharmaceutical formulations requires the addition of lubricants to reduce ejection forces, prevent tooling damage and tablet defects. The internal addition of lubricants is known to reduce tablet tensile strength, especially of mainly plastically deforming materials. To date, available models show only limited quantitative predictive accuracy for the influence of lubricant concentration on the mechanical strength of tablets. This study aims to fill this gap and present a model based on the Ryshkewitch-Duckworth equation that can estimate the compactibility profiles of lubricated formulations. Binary mixtures of different diluents (microcrystalline cellulose and lactose) were prepared with common lubricants (magnesium stearate and sodium stearyl fumarate) and subsequently tableted. The resulting compactibility profiles were fitted using the Ryshkewitch-Duckworth equation and the derived fit parameters (k_b and σ₀) were correlated with the lubricant concentration. Subsequently, an empirical model was established which requires a minimum of experimental data and is able to predict the tensile strength of lubricated diluent tablets. Consequently, the developed empirical model is an interesting and valuable addition to the existing multi-component compacting models available and offers the opportunity to accelerate experimentation in the development of new tablet formulations.

Masses of nasal cavity, paranasal sinuses and nasopharynx: A clinicopathological study

An analysis of clinicopathological features of 240 cases presenting as mass in nasal cavity, paranasal sinuses and nasopharynx observed, both retrospectively and prospectively, over a period of 5 years in Jawaharlal Nehru Medical College. Aligarh. The incidence of masses in nasal cavity, paranasal sinuses and nasopharynx was 34.3 cases per year. Amongst the 240 cases studied, there were 144 cases (60%) of non-neoplastic lesions, 56 cases (23.33%) of benign lesions and 40 cases (16.67%) of malignant lesions. All age groups were involved and the mean age of presentation with the increasing age were: - non-neoplastic (22.5 years), benign tumors (26.8 years) and malignant tumors (35.3 years). The male to female ratio was 1.7:1 for non-neoplastic lesions; 3:1 for benign tumors: and 2.3:1 for malignant lesions. In this study maximum number of cases were present in nasal cavity (65%) followed by paranasal sinuses (20%) and least number of cases involved the nasopharynx (15%). The relative number of non-neoplastic and neoplastic lesions varies from region to region. A provisional diagnosis was made after clinical assessment and radiological investigation but final diagnosis was made after histopathological examination.

Clinicopathological study of non-neoplastic lesions of nasal cavity and paranasal sinuses

An analysis of cases presenting as mass in nasal cavity (NC), paranasal sinuses (PNS), and nasopharynx (NP) was done over a period of 7 years in Jawaharlal Nehru Medical College, Aligarh. A provisional diagnosis was made after clinical assessment and radiological investigations, but final diagnosis was made after histopathological examination. The incidence of masses in NC, PNS, and NP was 34.3 cases per year, non-neoplastic lesions constituted 60% of these cases and their incidence was 20.7 cases per year. All the cases were carefully examined histopathologically and it was found that the region was affected by a variety of non-neoplastic lesions. Among 240 cases, 145 were non-neoplastic and 95 were neoplastic The lesions in the decreasing order of frequency were - nasal polyp, rhinoscleroma, tuberculosis, fungal infection, fibrous dysplasia, ossifying fibroma, cysts, nasal glioma, and cemento-ossifying fibroma. NP was involved by a range of neoplastic lesions; however, no non-neoplastic lesion was seen in this region.

SR proteins ASF/SF2 and SRp55 participate in tissue factor biosynthesis in human monocytic cells

BACKGROUND

Human monocytes express two naturally occurring forms of circulating tissue factor (TF) - full-length TF, a membrane-spanning protein, and alternatively spliced TF, a soluble molecule. Presence of the variable exon 5 in TF mRNA determines whether the encoded TF protein is transmembrane, or soluble. Recently, an essential SR protein ASF/SF2 was implicated in TF pre-mRNA processing in human platelets.

OBJECTIVE

To examine molecular mechanisms governing regulated processing of TF pre-mRNA in human monocytic cells.

METHODS AND RESULTS

In silico analysis of the human TF exon 5, present only in full-length TF mRNA, revealed putative binding motifs termed exonic splicing enhancers (ESE) for the SR proteins ASF/SF2 and SRp55, which were found to be abundantly expressed in monocytic cell lines THP-1 and SC, as well as monocyte-enriched peripheral blood mononuclear cells (PBMC). Using a splice competent mini-gene reporter system transiently expressed in monocytic cells, it was determined that weakening of either five closely positioned ASF/SF2 ESE (bases 87-117) or a single conserved SRp55 ESE (base 39) results in severe skipping of exon 5. ASF/SF2 and SRp55 were found to physically associate with the identified ESE.

CONCLUSIONS

SR proteins ASF/SF2 and SRp55 appear to interact with the variable TF exon 5 through ESE at bases 39 and 87-117. Weakening of the above ESE modulates splicing of TF exon 5. This study is the first to identify and experimentally characterize cis-acting splicing elements involved in regulated biosynthesis of human TF.