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Biomedical subjects

R Pandey

Publications and source records attributed to R Pandey.

At least 91 records · Page 5Linked to original sources
PubMed1994

Pathogenicity of a subgroup C feline leukemia virus (FeLV) is augmented when administered in association with certain FeLV recombinants.

There is evidence to suggest that infectious feline leukemia viruses (FeLVs) may be altered biologically because of homologous recombination with non-infectious endogenous FeLV (enFeLV) sequences in the infected cells. To evaluate the role of such recombination events in FeLV pathogenesis, a molecular clone of subgroup C FeLV, Sarma strain (FSC), was tested for induction of aplastic anemia in the absence or presence of mixtures of recombinants between FSC and an enFeLV element. In the recombinants, FSC sequences in the viral surface glycoprotein (SU) protein were variably replaced by the corresponding sequences of the enFeLV. The results showed that the virus mixtures varied in their infectivity to neonatal specific pathogen-free cats. One group of mixtures, although exhibiting relatively reduced infectivity, represented the most acute disease-inducing agents. The presence of recombinants in this mixture significantly accelerated the development of erythrocyte aplasia compared to cats infected with FSC alone. In addition, infected cells appeared to be distributed differently in various hematopoietic organs with respect to infection with FSC versus viral mixture. Viral recombinants which were present in this inoculum mixture, however, could not be detected in the plasma or infected tissues of the cats at the end stage of the disease, although their presence in the plasma at the early stages could be detected. Clearly, parental FSC outgrew the recombinants in the infected animals, since its detection was prominent at all stages of the progression of the disease. Therefore, we hypothesize that recombinants initially present in the infected animals, while only poorly replicated compared to FSC in the host, might have had the opportunity to infect certain target cells (potentially erythroid progenitor cells) and then disappeared with the associated cytopathic effect.

Animals↗
PubMed1994

Abnormal processing of a recombinant feline leukemia virus envelope polyprotein and its interference with subgroup C virus infection.

Processing of the env polyprotein of a noninfectious feline leukemia virus (FeLV) recombinant, named r6gp, was examined in human-transfected cells. The r6gp provirus was previously generated in the frame of FeLV, subgroup B, GA clone with substitution of all but 40 C-terminal amino acid sequences of the surface glycoprotein (SU) from an endogenous FeLV provirus element (CFE-6). Although r6gp produced a normal size (85 kDa) env glycoprotein precursor, the product, unlike the precursor of the parental virus, was neither additionally glycosylated nor further processed into mature env proteins. Biochemical observations were consistent with the idea that the chimeric env polyprotein was trapped in the endoplasmic reticulum (ER) and were directly supported by immunofluorescence microscopy analyses. Interestingly, the residence of the chimeric protein in the ER specifically interfered with FeLV, subgroup C (Sarma) virus infection but not the parental FeLV-B virus infection. Since FeLV-C provirus sequences could be readily detected in the infected cells, it appeared that r6gp env expression did not block entry of the challenge virus. While FeLV-B and CFE-6 env genes share an extensive overall sequence homology, a variable region (region VI) of CFE-6 near the C-terminus of SU, which was retained in the r6gp construct, exhibits a considerably higher degree of homology to FeLV-C than FeLV-B. Thus, we propose that region VI is involved in conferring specificity for the env polyprotein oligomerization in the ER, and that co-oligomerization of the trapped r6gp env with FeLV-C is the reason for specific interference with FeLV-C infection. The results also demonstrate for the first time a functional abnormality of a recombinant FeLV env gene which is structurally similar to those commonly detected in FeLV-induced feline lymphosarcomas.

Amino Acid Sequence↗
PubMed1994

Gliosarcomas: pathological spectrum.

Pathological spectrum as seen in sixteen cases of gliosarcomas out of 81 cases of glioblastomas is described. Temporal lobe involvement (37.5%) and fibrosarcomatous pattern (62.5%) were found to be most frequent. Osteochondromatous element was found in recurrence of one gliosarcoma. Minimal criteria for diagnosis, pitfalls in diagnosis, differential diagnosis and histogenesis of gliosarcoma are discussed.

Adolescent↗
PubMed1994

Pedunculated hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the commonest malignant tumor of the liver. Pedunculated HCC, however, is rarely observed. A pre-operative diagnosis before the advent of current imaging modalities was often difficult. A patient of pedunculated HCC presenting as a mobile abdominal lump, managed successfully by surgery, is reported herein.

Carcinoma, Hepatocellular↗
PubMed1994

Recombination between feline exogenous and endogenous retroviral sequences generates tropism for cerebral endothelial cells.

Brain tissues of domestic cats that died of aplastic anemia from infection with either parental feline leukemia virus (FeLV), subgroup C, or a mixture of FeLV-C and recombinants between FeLV-C and an endogenous FeLV provirus were examined by the immunoperoxidase staining technique using a monoclonal antibody (C11D8) directed against an epitope of the viral surface glycoprotein (SU). Positive staining of the central nervous system (CNS) capillary endothelial cells with no labeling on neuronal or glial cells was observed in cats that were inoculated with the virus mixture. This was in contrast to brain tissue of cats infected with FeLV-C alone, which showed no such staining. While non-CNS endothelial cells derived from human umbilical vein (HUVEC) could be readily infected in culture by FeLV-C, endothelial cells derived from human retina (REC) or brain (BEC) were resistant to infection by this parental virus. These latter cells in culture, however, could be infected by the viral mixture. The data suggested that at least one or more of the presumptive recombinant viruses could specifically infect CNS-derived endothelial cells. Using polymerase chain reaction and DNA sequencing strategies to amplify and analyze DNA fragments of the proviral SU region from cells infected with REC-selected viruses, we found the occurrence of a single recombinant in which two-thirds of the SU gene from the N-terminus of FeLV-C was replaced by the endogenous FeLV element. This recombinant virus, when molecularly cloned, should be useful in determining its potential in vivo neuropathogenicity.

Anemia, Aplastic↗
PubMed1993

Intracranial tuberculomas: MRI signal intensity correlation with histopathology and localised proton spectroscopy.

In seven cases of intracranial tuberculomas showing different signal intensities on MRI (five characteristic and two nonspecific), detailed histopathological examination was performed to look for number of macrophages, fibrosis, gliosis, degree of inflammatory cellular infiltrate, and type of caseation. The granulomas showing more macrophages, fibrosis and gliosis appeared hypointense on T2-weighted images. Tuberculomas showing minimal macrophages, marked cellular infiltration, and minimal fibrosis appeared hyperintense on T2-weighted images. Lesions showing similar signal intensity on T2-weighted images showed variation in the amount of macrophages, cellular infiltrates, maturity and fibrosis. Trace element estimation was done (iron, copper, and magnesium) in two of these lesions appearing hypointense on T2 and two normal brain samples; these were significantly lower in tuberculoma compared to normal brain tissue. Localised proton spectroscopy was performed in two hypointense lesions which showed marked increase in peaks in the region of mobile lipids (1.28 ppm) compared to normal brain parenchyma. It is concluded that the signal intensity of the lesions is dependent on the number of macrophages, fibrosis and cellular infiltrates. In addition increased lipid contents in the tuberculoma also contribute to the hypointensity on T2-weighted images.

Adult↗
PubMed1993

Tuberculosis of the thyroid gland: a clinicopathological profile of four cases and review of the literature.

Four cases of tuberculosis of the thyroid with different presentations including chronic sinus (following drainage of thyroid abscess), thyrotoxicosis, severe dysphagia clinically mimicking malignancy and euthyroid multinodular goitre are described. Except in the case presenting with chronic sinus (discharging acid-fast bacilli), the diagnosis was a pathological surprise (cytopathology in one and histopathology in two). Only in one case was there evidence of disease outside the cervical region. All cases showed multiple coalescing and caseating epitheloid cell granulomas along with giant cells, which are considered as diagnostic of tuberculous thyroiditis even if acid fast bacilli cannot be demonstrated. The literature is reviewed and the pathogenesis discussed.

Adult↗
PubMed1993

Recombinant feline leukemia virus genes detected in naturally occurring feline lymphosarcomas.

Using a polymerase chain reaction strategy aimed at detecting recombinant feline leukemia virus (FeLV) genomes with 5' env sequences originating from an endogenous source and 3' env sequences resulting from FeLV subgroup A (FeLV-A), we detected recombinant proviruses in approximately three-fourths of naturally occurring thymic and alimentary feline lymphosarcomas (LSAs) and one-third of the multicentric LSAs from cats determined to be FeLV capsid antigen positive by immunofluorescence assay. In contrast, only 1 of 22 naturally arising FeLV-negative feline LSAs contained recombinant proviruses, and no recombinant env gene was detected in seven samples from normal tissues or tissues from FeLV-positive animals that died from other diseases. Four preferred structural motifs were identified in the recombinants; one is FeLV-B like (recognizing that FeLV-B itself is a product of recombination between FeLV-A and endogenous env genes), and three contain variable amounts of endogenous-like env gene before crossing over to FeLV-A-related sequences: (i) a combination of full-length and deleted env genes with recombination at sites in the middle of the surface glycoprotein (SU), (ii) the entire SU encoded by endogenous-like sequences, and (iii) the entire SU and approximately half of the transmembrane protein encoded by endogenous-like sequences. Additionally, three of the thymic tumors contained recombinant proviruses with mutations in the vicinity of the major neutralizing determinant for the SU protein. These molecular genetic analyses of the LSA DNAs correspond to our previous results in vitro and support the occurrence and association of viral recombinants and mutants in vivo in FeLV-induced leukemogenesis.

Amino Acid Sequence↗
PubMed1993

Histological and mucin secretion patterns in solitary rectal ulcer syndrome.

OBJECTIVE: Histological and mucin secretion patterns were studied in 32 cases of solitary rectal ulcer syndrome. METHODS: Biopsy sections stained with hematoxylin and eosin, Masson's trichrome and alcian blue with PAS at pH 1.0 and pH 2.5 were examined. RESULTS: Fibrosis and smooth muscle extension in lamina propria and hypertrophy of muscularis mucosa were the most frequent histological findings. Sialomucin was present in all cases, in contrast to sulphomucin which is normally present. CONCLUSION: Mucin staining pattern appears to be a helpful diagnostic marker of solitary rectal ulcer syndrome and may be helpful in differentiating it from other non-malignant conditions.

Humans↗
PubMed1993

Fusion activity dissociated from replication ability in feline immunodeficiency virus (FIV) in human cells.

Multinucleated-giant-cell formation followed by cell killing was observed after cocultivation of the feline immunodeficiency virus (FIV)-producing feline T-cell line 3201/FIV with various human cells, including T-cell lines carrying human T-cell lymphotropic virus type I (HTLV-I). The susceptibility to giant cell formation varied with the cell lines tested. Cocultivation of irradiated 3201/FIV cells with MT-2 cells resulted in giant cell formation as early as 2 h in culture, with striking resemblance to that induced by human immunodeficiency virus (HIV). MT-4 cells (HTLV-I positive) and H9 cells (HTLV-I negative) were less susceptible than MT-2 to the induction of syncytia. MOLT-4 cells (HTLV-I negative) had intermediate sensitivity to syncytia formation. No syncytia were observed in the monocytic cell line U-937 (HTLV-I negative). Syncytia formation between 3201/FIV and MT-2 cells was inhibited by polyclonal cat anti-FIV antisera but not polyclonal cat anti-feline leukemia virus (FeLV) antisera, goat anti-FeLV, uninfected specific-pathogen-free cat serum, human anti-HTLV-I antisera, or normal human and goat serum. Concentrated cell-free FIV supernatant from 3201/FIV also induced giant cells of MT-2 cells that were indistinguishable from those induced by cocultivation. Giant cells and extensive cell killing associated with giant cell formation declined and disappeared within 10 days. Surviving cells appeared to be of normal size and grew continuously without expressing FIV antigen or releasing infective virus. Although Southern blot analysis using probes specific for FIV could not detect proviral DNA in any of the five human cell lines cocultured with irradiated 3201/FIV cells, the polymerase chain reaction (PCR) technique detected FIV-specific DNA in MOLT-4 cells. DNA from the FIV-PCR positive MOLT-4 cells was PCR negative for endogenous FeLV-specific sequences, indicating that the MOLT-4 cell DNA was not contaminated with DNA from feline cells (i.e., 3201 cells). The FIV-MOLT-4 cells remained PCR positive for FIV after 40 passages, suggesting stable integration in the human cell line. These findings indicate that FIV is capable of forming proviral DNA in human T-lymphoid cells by cocultivation, although this FIV-carrying human cell line failed to produce replication-competent viruses.

Animals↗
PubMed1993

Actinomycosis mimicking carcinoma of the maxillary sinus.

Human actinomycosis may pose a diagnostic problem at times and is often mistaken for a neoplasm. A thirty-five year old male was clinically diagnosed as a case of carcinoma of the right maxillary sinus on the basis of history, clinical presentation and radiologic findings. Tissue biopsy was negative for malignancy on three consecutive occasions. Microscopic examination showed bits of granulation tissue and fragments of filamentous structures. On microbiological examination, Actinomyces israelii was isolated and fungus culture was negative. Long term Penicillin treatment caused disappearance of all signs and symptoms. The report highlights the importance of bearing in mind the fact that certain rare, chronic, suppurative granulomatous infections, like actinomycosis, may mimic malignancy.

Actinomycosis, Cervicofacial↗