Kinetics of inhibited or retarded polymerization. Investigations on the cerium(IV)/toluene/acrylonitrile system

The kinetics and mechanism of the inhibiting action of toluene on the Ce(IV) initiated polymerization of acrylonitrile were studied together with the effects of [M], [Ce(IV)], [Toluene], [HClO₄], [NaClO₄], and [Acetic acid] on the rate of polymerization. The values of composite rate constant kk_t/k_pk_ok_i for toluene (and substituted toluenes) was calculated by plotting [M]/R_p versus [M]^?1. A very significant observation in the present study was that the plot of [M]/R_p versus [M]^?1 gave a negative intercept, which seems to be a general observation for all inhibiting substrates. On the basis of the experimental data, it could be concluded that the benzyl radical obtained by hydrogen abstraction, and not a chain transfer, is responsible for the inhibition.     

Fine-needle aspiration cytology of meningiomas with unusual presentations

Meningiomas are not often aspirated unless they erode the skull, occur intraorbitally, or present as swelling in the head and neck region. We describe the cytologic findings of fine-needle aspiration cytology (FNAC) in four cases of meningioma that presented with swellings in the head and neck region. The patients underwent surgery, and the diagnosis of meningioma was confirmed. Three of the four cases were reported as aggressive meningiomas on histopathology.     

Entomophthoromycosis in South Bengal (Eastern India): a 9 years study

Subcutaneous mycoses caused by the family Entomophthoraceae is very rare type of disease and is being reported sporadically from various Tropical countries including India. Here we report 8 cases of rhinoentomophthoromycosis caused by Conidiobolous coronatus and 7 cases of chronic subcutaneous phycomycosis caused by Basidiobolus ranarum. Cases were detected during a span of 9 years between 1991 to 1999, from 9 districts in and around Kolkata (Eastern India). Former type of lesions were detected among 20 to 65 age group of healthy individuals, predominantly males (7:1). In the latter type, male-female ratio was 2:5, and except for one all cases belonged to below 20 years age group of healthy individuals. Several cases were detected only after examination of repeat biopsy samples. With high degree of clinical suspicion, right approach is needed for laboratory confirmation of diagnosis.     

Controversies in surgical pathology: minimal involvement of sentinel lymph node in breast carcinoma: prevailing concepts and challenging problems

Sentinel lymph node biopsy has attained "standard of care' status in the management of breast carcinoma. However, the pathological interpretation and clinical consequences of "minimally involved' sentinel lymph nodes remain controversial. Herein, we present some of the complex and challenging pathological problems inherent in this evolving setting. Clearly, at least some of our current concepts regarding "minimally involved' sentinel lymph nodes need reappraisal.     

Characterization and physical map of choleraphage φ149 DNA

Choleraphage φ149 DNA is a linear double-stranded molecule 69 × 10⁶ Da or 104 kilobase pairs (kbp). From restriction enzyme analysis, it has been concluded that the DNA is circularly permuted. There are at least three S1 nuclease-sensitive sites along the length of the molecule. These sites represent single-strand interruptions repairable by T4 DNA ligase. A physical map of the DNA has been constructed using the restriction endonucleases BamH1 and BglII.     

Knowledge-based computer system to aid in the histopathological diagnosis of breast disease.

A knowledge-based computer system, designed to assist pathologists in the histological diagnosis of breast disease, is described. This system represents knowledge in the form of "disease profiles" and uses a novel inference model based on the mathematical technique of hypergraphs. Its design overcomes many of the limitations of existing expert system technologies when applied to breast disease. In particular, the system can quickly focus on a differential problem and thus reduce the amount of data necessary to reach a conclusion. The system was tested on two sets of samples, consisting of 14 retrospective cases and five hypothetical cases of breast disease. Its recommendations were judged "correct" by the evaluating pathologist in 15 cases. This study shows the feasibility of providing "decision support" in histopathology.     

Evaluation of two commercially available anti human immunodeficiency virus antibody ELISA Kits using clinical samples

Laboratory diagnosis is the mainstay in the diagnosis of HIV infection in an individual. The wide range of diagnostic kits available, for the detection of anti HIV antibodies, makes it mandatory that the kits are evaluated before they are made available in the market. We evaluated the performance of a Microlisa HIV kit (J. Mitra & Co.) using a panel of HIV reactive and non reactive clinical specimens. The sensitivity and specificity of the kit were found to be 100% as compared to the UBI HIV 1/2 EIA kit. The ease of testing, the assay characteristics including efficiency of the Microlisa favour its use by laboratories as a primary screen for HIV infection.     

Crosslinked chitosan: its physical properties and the effects of matrix stiffness on chondrocyte cell morphology and proliferation

Chitosan [beta(1-4)-2 amino-2-deoxy-D-glucose], the natural polyaminosaccharide derived from N-deacetylation of chitin [beta(1-4)-2 acetamide-2-deoxy-D-glucose], has been shown to possess attractive biological and cell interactive properties. Recently chitosan and chitosan analogs have also been shown to support the growth and continued function of chondrocytes. In the present study, chitosan substrates are crosslinked with a functional diepoxide (1,4 butanediol diglycidyl ether) to alter its mechanical property, and the viability and proliferation of the canine articular chondrocytes seeded on the crosslinked surface are further assayed. Of interest is the impact of substrate stiffness on the growth and proliferation of articular canine chondrocytes. Crosslinked scaffolds were also subjected to degradation by chitosanase to examine the impact of crosslinking on enzyme-assisted degradation. The hydrophilicity and compression modulus of the crosslinked surfaces were measured via contact-angle measurements and compression tests, respectively. Scanning electron microscopy (SEM) and fluorescent staining were used to observe the proliferation and morphology of chondrocyte cells on noncrosslinked and crosslinked surfaces. The crosslinked chitosan was found to be nontoxic to chondrocytes and more hydrophilic. Its compression modulus and stiffness increased, which may improve the scaffold resistance to wear and in vivo shrinkage once implanted. The increased stiffness also seemed to serve as an additional mechanical stimulus to promote chondrocyte growth and proliferation. The cell morphology on crosslinked scaffolds seen by SEM and fluorescent stain was the typical chondrocytic rounded shape. The method proposed provides a nontoxic way to increase the mechanical strength of the chitosan scaffolds.