National intercomparisons of I radioactivity measurements in nuclear medicine centres in India

National intercomparisons of activity measurements of ¹³¹I, a radioisotope widely used for diagnosis and therapy of thyroid related ailments, were initiated in 1979 as a quality assurance program, towards improving radiation safety procedures and related dosimetry in Nuclear Medicine Centres (NMCs) in India. Oral administration of a known quantity of radioiodine to patients requires accurate radioactivity measurements to be performed on a well-calibrated isotope calibrators. Under or over estimation of the activity due to a faulty or uncalibrated isotope calibrator could provide misleading results. Calibration of isotope calibrators and the traceablity of subsequent measurements to the national standards laboratory is one of the essential basic radiation safety requirement of the IAEA. In view of the stringent quality assurance requirements for activity measurements imposed by Atomic Energy Regulatory Board, a National Intercomparison Program was initiated and to date ten such intercomparison programs have been conducted by the Radiation Safety Systems Division, of the Bhabha Atomic Research Centre. This program has benefited the participants by making their measurements traceable to the National Primary Standards. Over the years there has been a marked increase in the number of NMCs participating in the intercomparison programs. As a result, the number of institution showing large deviation from the correct value has decreased considerably over the years. This program thus, has enabled participating NMCs to check their isotope calibrators so as to ensure proper delivery of radiation dose to the patients and hence to optimise patient exposure.     

Non-HIV-Related Progressive Multifocal Leukoencephalopathy (PML): A Tertiary Cancer Center Experience

In the course of 1 year at a tertiary cancer center, 3 patients (2 men; 1 woman; age 51-75 years) were seen in neurological consultation (1.5% of all consultations). Clinical course in all patients was of a progressive neurologic disorder not consistent with either a primary or secondary malignancy. Magnetic resonance (MR) imaging was most informative with respect to diagnosis and subsequent management. Brain biopsy was performed in all patients to assist in both diagnosis and prognostication. All patients were determined to have progressive multifocal leukoencephalopathy (PML) by brain biopsy.     

Brain abscess in Saudi Arabia

There are significant variations among countries in the incidence of brain abscess. We report here 26 cases of brain abscess treated at the Neurosurgery Department of King Faisal University and Dammam Central Hospital Saudi Arabia over a six year period (1982–1988). This is 2.3% of total admissions to the two neurosurgery departments serving a population of approximately 1.2 million in the same period.Young males were most often affected (M/F ratio 3.3:1; 31% were less than 15 years old, 46% aged between 15–39 years, and 23% older than 40 years). Streptococcus was found to be the most common microorganism (38.4%). Mixed infection was seen in 15.3%, and sterile abscesses were found in 11.5% of the patients after aerobic and anaerobic cultures of the pus. Chronic otitis media and paranasal sinusitis predisposed the patients to abscess formation in 57.6% of the cases. The temporo-parietal area was the commonest site. Epilepsy was a complication in 30.7% of our patients, and the mortality rate was 15.3%.     

Changes in UK ORL-HNS training scheme: Does the Indian trainee have a place anymore?

The determination of the UK Government to modernise medical careers, the shortage of training jobs for local medical graduates, the establishment of the Postgraduate Medical Training and Education Board (PMETB) and European Union rules have combined to change the scheme of surgical training in the United Kingdom. In the opinion of the author, the Indian Otorhinolaryngological (ORL) trainee can no longer aspire to reasonable higher training in the UK.     

Evolution of the neuropeptide Y receptor family: gene and chromosome duplications deduced from the cloning and mapping of the five receptor subtype genes in pig

Neuropeptide Y (NPY) receptors mediate a variety of physiological responses including feeding and vasoconstriction. To investigate the evolutionary events that have generated this receptor family, we have sequenced and determined the chromosomal localizations of all five presently known mammalian NPY receptor subtype genes in the domestic pig, Sus scrofa (SSC). The orthologs of the Y(1) and Y(2) subtypes display high amino acid sequence identities between pig, human, and mouse (92%-94%), whereas the Y(4), Y(5), and y(6) subtypes display lower identities (76%-87%). The lower identity of Y(5) is due to high sequence divergence in the large third intracellular loop. The NPY1R, NPY2R, and NPY5R receptor genes were localized to SSC8, the NPY4R to SSC14, and NPY6R to SSC2. Our comparisons strongly suggest that the tight cluster of NPY1R, NPY2R, and NPY5R on human chromosome 4 (HSA4) represents the ancestral configuration, whereas the porcine cluster has been split by two inversions on SSC8. These 3 genes, along with adjacent genes from 14 other gene families, form a cluster on HSA4 with extensive similarities to a cluster on HSA5, where NPY6R and >13 other paralogs reside, as well as another large cluster on HSA10 that includes NPY4R. Thus, these gene families have expanded through large-scale duplications. The sequence comparisons show that the NPY receptor triplet NPY1R-NPY2R-NPY5R existed before these large-scale duplications.     

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.     

Malassezia furfur in a case of onychomycosis: colonizer or etiologic agent?

The etiologic role of Malassezia furfur in onychomycosis is a contentious diagnostic problem because its keratinolytic ability has never been verified. This case report describes the isolation of M. furfur from the infected nails of a child clinically diagnosed with onychomycosis, and discusses the role of this organism as an etiologic agent/colonizer. The patient presented with subungual hyperkeratosis and onycholysis without associated paronychia. Budding yeast cells compatible with M. furfur were repeatedly demonstrated in KOH wet mounts of damaged nails, histopathology of hematoxylin and eosin (H&E) and periodic acid-Schiff (PAS) stained sections showed penetration of fungal elements between deeper layers of keratin, and numerous colonies of M. furfur were isolated on three consecutive occasions from nail specimens collected from different areas of hand and toenail lesions. No evidence of nail invasion by dermatophytic or nondermatophytic filamentous fungi were found by direct microscopy or culture. Microscopy and culture were negative following 12 weeks of ketoconazole treatment, which resulted in growth of healthy nail plates with normal beds. We can infer from these observations that M.furfur was an etiologic agent rather than a colonizer in the patient's nails even though direct keratinolytic character of this fungus was not demonstrated.