Flanking regulatory sequences of the locus encoding the murine GDNF receptor, c-ret, directs lac Z (beta-galactosidase) expression in developing somatosensory system.

RET forms the catalytic component within the receptor complex that transmits signals from the GDNF family of neurotrophic factors. To study the mechanisms regulating the cell-type specific expression of this gene, we have cloned and characterised the murine c-ret locus. A cosmid contig comprising approximately 60 kb of the mouse genome encompassing the entire structural gene and flanking sequences have been isolated and the transcription initiation site identified and promoter characterised. The murine c-ret promoter lacks a TATA initiation motif and has GC enriched DNA sequences reminiscent of CpG islands. Analysis of transgenic mice lines bearing the Lac Z (beta-galactosidase) reporter gene under the control of 5' flanking sequences show modularity in the organisation of cis-regulatory domains within the locus. Cloned 5' flanking sequences comprise a distal regulatory domain directing Lac Z expression at the primitive streak, lateral mesoderm and facial ganglia and a proximal sensory neurones specific regulatory domain inducing Lac Z expression primarily within the developing somatosensory system. The spatial and temporal progression of transgene expression precisely recapitulates endogenous gene expression in developing sensory ganglia including its induction in postnatal Isolectin B4 binding nociceptive neurones.

Signalling by the RET receptor tyrosine kinase and its role in the development of the mammalian enteric nervous system.

RET is a member of the receptor tyrosine kinase (RTK) superfamily, which can transduce signalling by glial cell line-derived neurotrophic factor (GDNF) and neurturin (NTN) in cultured cells. In order to determine whether in addition to being sufficient, RET is also necessary for signalling by these growth factors, we studied the response to GDNF and NTN of primary neuronal cultures (peripheral sensory and central dopaminergic neurons) derived from wild-type and RET-deficient mice. Our experiments show that absence of a functional RET receptor abrogates the biological responses of neuronal cells to both GDNF and NTN. Despite the established role of the RET signal transduction pathway in the development of the mammalian enteric nervous system (ENS), very little is known regarding its cellular mechanism(s) of action. Here, we have studied the effects of GDNF and NTN on cultures of neural crest (NC)-derived cells isolated from the gut of rat embryos. Our findings suggest that GDNF and NTN promote the survival of enteric neurons as well as the survival, proliferation and differentiation of multipotential ENS progenitors present in the gut of E12.5-13.5 rat embryos. However, the effects of these growth factors are stage-specific, since similar ENS cultures established from later stage embryos (E14. 5-15.5), show markedly diminished response to GDNF and NTN. To examine whether the in vitro effects of RET activation reflect the in vivo function(s) of this receptor, the extent of programmed cell death was examined in the gut of wild-type and RET-deficient mouse embryos by TUNEL histochemistry. Our experiments show that a subpopulation of enteric NC undergoes apoptotic cell death specifically in the foregut of embryos lacking the RET receptor. We suggest that normal function of the RET RTK is required in vivo during early stages of ENS histogenesis for the survival of undifferentiated enteric NC and their derivatives.

Characterization of mouse fibroblast (NIH3T3) and fibrosarcoma cell lines (WEHI-164 and MFS 8) using PMRS.

Proton magnetic resonance Spectroscopy (PMRS) has been used to study the differences between immortalized fibroblasts and fibrosarcoma cells of different grade. One and two dimensional purged correlation spectroscopy (PCOSY) have been used to assess intact viable fibroblast and fibrosarcoma cells, and differences in the triglyceride, cellular metabolite, and cell surface fucosylation patterns between the three cell lines have been observed. The clinical implication of this study is the potential use of PMRS as an adjunct to conventional histopathology.

Interaction of filarial proteins on growth regulation of normal lung epithelial cells in vitro.

An in vitro model to examine the effects of filarial proteins on lung epithelial cells has been developed. Several of these proteins appear in circulation of infected individuals. A close association between tropical pulmonary eosinophilia (TPE) and filariasis has been reported by several workers. [3H]-thymidine studies do indicate that when optimum concentration of these filarial proteins were added to lung cultures in proliferating and basal/maintenance media a further increase in growth stimulation was observed early in culture. However, on longer exposures and at higher concentrations an inhibitory effect with distinct morphological changes were noted. The dual role of these proteins on lung epithelial cells in vitro may highlight the possibility of a direct interaction of these proteins with lung cells during disease also contributing to tissue damage.

Induction chemotherapy in non-metastatic high grade osteo sarcomas--results of pilot study at Cancer Institute (WIA), Madras.

Twelve patients with high grade osteosarcomas of the extremities were treated with two cycles of induction chemotherapy using adriamycin and cis-platinum and sandwich radiation between the two cycles (4000 rads). Ten patients underwent amputation or disarticulation, two patients had wide excision followed by endoprosthesis. The specimen was assessed for grade of necrosis. The Disease Free Survival at a minimum follow-up period of 26 months and median follow-up period of 35.5%. All the five patients who developed distant metastases had shown only a grade I necrosis in the tumour.

Exclusive asymptomatic neonatal infections by human rotavirus strains having subgroup I specificity and "long" RNA electropherotype.

A large number of stool specimens, of healthy newborn infants, collected from various hospitals and clinics in Bangalore City, India, have been examined for the presence of asymptomatic rotaviral excretion. Out of 370 samples analysed during a three year period from 1988 to 1991, 133 specimens (36%) were positive for rotavirus RNA. All these asymptomatic neonatal strains, without exception, showed "long" RNA pattern, but subgroup I specificity. Serotype analysis by ELISA or by hybridization with serotype-specific probes indicated that these strains probably represent a new serotype in newborn children. We find an exclusive association of human rotaviruses having "long" RNA pattern and subgroup I specificity with asymptomatic neonatal infections in contrast to the earlier observations of association of such unusual strains with acute gastroenteritis in young children.

Campylobacter diarrhea in children in Trivandrum.

One hundred and fifty two stool samples from patients belonging to the pediatric age group clinically diagnosed as acute diarrhea/dysentery were processed for thermophilic campylobacters. C. jejuni was isolated from 9 samples (5.9%). Five of the C. jejuni isolates were from children who presented with bloody diarrhea and 4 were from those who had watery diarrhoea. Though the pathogenic role of C. jejuni in these cases is not proved, this study indicates the prevalence of the organism in Trivandrum district.

Acute carcinoid syndrome: a complication of flexible fiberoptic bronchoscopy.

We report the case of a patient with functioning bronchial carcinoid tumor found as a solitary nodule. Acute carcinoid syndrome developed during transbronchial biopsy, and life-threatening hypotension occurred during operation. We emphasize that carcinoid tumors should be considered in the differential diagnosis of solitary nodules, and such a complication should be kept in mind when endobronchial or transbronchial biopsy is performed.

Histoenzmological mapping of ATPase and 5-nucleotidase in the spinal cord and medulla oblongata of hedgehog (Paraechinus micropus).

The contribution presented deals with the distribution of adenosine triphosphatase (ATP-A) and 5-nucleotidase (AMP-A) in the spinal cord and medulla oblongata of hedgehog. The highlights of this study are: (1) AMP-A activity is stronger in neuropil than in neurons, in all the areas of spinal cord and medulla oblongata. In the nerve cells the enzyme is localized at the peripheries of the neurons, whereas the cytoplasm and nuclei are completely free from enzymatic activity. Reaction in blood vessels is quite high both in gray and white matter. (2) ATP-A activity is seen mainly at the peripheries of the neurons. The neuropil activity varies from mild to intense. Reaction in blood vessels is quite strong in all the areas. (3) Fibrous bundles and tracts are negative for both the enzymes. (4) In general, the activity of ATP-A and AMP-A is strongest in cranial nerve nuclei, irrespective of their sensory or motor nature. The distribution of these enzymes has been correlated with the functions of various nuclei of spinal cord and medulla oblongata in hedgehog, and compared with other mammals.

A comparative histochemical mapping of acid phosphatase, 5-nucleotidase and non-specific esterase in the olfactory bulbs of rabbit and hedgehog.

The paper deals with comparative account of the distribution of acid phosphatase 5-nucleotidase and non-specific esterase in the olfactory bulbs of rabbit and hedgehog. The acid phosphatase is observed in all the neurons of both the animals. However, the concentration of the enzyme is higher in hedgehog as compared to rabbit. The intensity of 5-nucleotidase in all the layers of olfactory bulb of hedgehog is stronger than in the rabbit. Intensity of non-specific esterase is quite higher in the olfactory bulb of rabbit than of hedgehog. Along with comparison the distribution of these enzymes have been correlated with their role in the olfactory senses.

Mediastinal herniation of the pleural sac: occurrence in massive pleural effusion.

In a review of 50 patients with massive pleural effusion, mediastinal herniation of the pleural sac occurred in 16 patients (32 percent). Right-to-left herniation (ten patients) was more common than left-to-right (six patients). Herniation occurred only in the posteroinferior mediastinum (D5-D11). Fourteen patients had displacement of the mediastinum away from the side of pleural effusion. Disappearance of herniated sac in every patient following thoracocentesis confirmed the diagnosis.