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Biomedical subjects

U Prasad

Publications and source records attributed to U Prasad.

11 recordsLinked to original sources
PubMed1992

Expression of Epstein-Barr virus genes and of lymphocyte activation molecules in undifferentiated nasopharyngeal carcinomas.

Previous studies investigating the role of Epstein-Barr virus (EBV) in undifferentiated nasopharyngeal carcinoma (NPC) have been performed on extracts from biopsies. The authors analyzed expression and localization of viral gene products in 18 undifferentiated NPCs at the cellular level using immunohistology and in situ hybridization. All cases were EBV-positive. The small nuclear EBV-encoded RNAs, EBERs, were regularly expressed whereas the latent membrane protein, LMP1, and EBV was detectable only in four cases (22%) and the nuclear antigen 2 was not detectable. The BZLF-1 protein of EBV which disrupts viral latency, was not detectable, confirming that the virus is latent in the tumor cells. Although the expression of the CD23 antigen in transplantable NPCs has been reported, our study demonstrates that expression of this antigen in human undifferentiated NPCs is rare. In contrast, almost all cases expressed the CDw70 antigen. Since in normal tissues this antigen is present only in activated lymphoid blasts, this finding may be relevant for the differential diagnosis of undifferentiated NPCs.

Antibodies, Monoclonal↗
PubMed1979

Ultrastructural studies on the replication of herpes virus ateles-73 in owl monkey kidney cells.

The replicative cycle of herpesvirus ateles, strain 73 (HVA-73), was examined in the electron microscope and compared to that of other herpesviruses known to be oncogenic. A relatively slow replicative cycle of HVA-73 in owl monkey kidney (OMK) cells allowed us to distinguish cytoplasmic and nuclear stages of replication, comprising virus uptake, transport, maturation, and extrusion. Virus uptake was observed within 10 hours of infection and occurred both as a result of fusion between virus and cell membranes and by phagocytosis. Morphologic evidence for the transfer of viral DNA from nuclecapsids to the nucleus at the nuclear membrane is presented. This is shown by the location of numerous empty capsids in front of nuclear pores early during infection. Towards the end of the eclipse phase, at about 48 hougs after infection, two different types of nuclear inclusion bodies were observed. Progeny nucleocapsids were detected in the nucleus at the same time. The envelopment of nucleocapsids occurred both at the nuclear membrane and at proliferating Golgi lamellae in the cytoplasm. Each site of envelopment is associated with the maturation of a characteristic, morphologically distinguishable virus particle. The assembly of HVA-73 resembled that of other oncogenic herpesviruses.

Adsorption↗
PubMed1978

Intracisternal tubular inclusions in nasopharyngeal carcinoma.

Biopsy specimens obtained from 20 cases of nasopharyngeal carcinoma were examined under electronmicroscope for the presence of Intracisternal Tubular Inclusions (ITI). In eight (40 per cent) of them these inclusions could be identified. Although the morphogenesis and significance of these ITI are not clearly understood, they have been found in several autoimmune and viral diseases, including infectious mononucleosis, a disease caused by EBV, and Burkitt's lymphoma, which is closely associated with EBV. Hence, the presence of ITI in NPC, another disease associated with EBV, seems to be of some significance. It is proposed that these inclusions could be the result of an immunological reaction initiated by injured cells infected with EBV, which acted as an antigen. The presence of another type of cytoplasmic inclusion, hitherto unknown, has also been reported.

Carcinoma↗
PubMed1978

Recent data and significance of intracisternal tubular inclusions in human and animal cells.

In 24 out of 60 patients with nasopharyngeal carcinoma (NPC) the cells were shown to contain a tubulo-reticular network in the dilated cisternae of the ergastoplasm which corresponds to the entity described previously as "intracisternal-tubular inclusion" (ITI). The significance of such inclusions is discussed in different pathological conditions and the literature is reviewed. This is the first report of such inclusions in nasopharyngeal carcinoma.

Animals↗
PubMed1978

Nasopharyngeal carcinoma and histocompatibility antigens.

New data are presented concerning the relationship between NPC and HLA antigens among Chinese. When attention is confined to newly diagnosed cases, it can be shown that, apart from the increased risk associated with the joint occurrence of A2 and B-Sin 2, there is also an increased risk associated with BW17 and a decrease in risk associated with A11. Among long-term survivors, however, BW17 is appreciably decreased, whereas A2 in the absence of B-Sin 2 or BW17 is increased. Among Malays, a non-Chinese group, there is an excess among NPC patients of a locus A blank, a blank which is probably associated with the AW19 complex.

Carcinoma↗
PubMed1975

Nasopharyngeal craniopharyngioma.

Two cases of cranipharyngiomas which were mainly located in the nasopharynz have been reported. The cystic nature of the tumour with leakage of brownish-coloured fluid helped in arriving at the diagnosis, which was confirmed on histology. Marsupulization through a transpalatal approach seems to be the treatment of choice in such cases.

Angiography↗