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Biomedical subjects

N Balachandran

Publications and source records attributed to N Balachandran.

At least 55 records · Page 3Linked to original sources
PubMed1984

Localization of a type-specific antigenic site on herpes simplex virus type 2 glycoprotein D.

A herpes simplex virus type 1 strain isolated from a recurrent lesion of the nose reacted with monoclonal antibodies recognizing a type 2-specific site on glycoprotein D but not with monoclonal antibodies recognizing other type 2-specific sites. DNA sequence analysis of the glycoprotein D gene of the isolate revealed a single nucleotide alteration which changed the codon for asparagine to one encoding histidine at amino acid 97 in the protein. Histidine is located at this position in glycoprotein of herpes simplex virus type 2; thus, the monoclonal antibody 17 beta A3 recognizes an epitope located at this region of the protein.

Adult↗
PubMed1983

B cell activation by cytomegalovirus.

Human cytomegalovirus is shown to be a nonspecific polyclonal B cell activator. The B cell response is independent of virus replication and requires little, if any, T cell help.

B-Lymphocytes↗
PubMed1982

Protection against lethal challenge of BALB/c mice by passive transfer of monoclonal antibodies to five glycoproteins of herpes simplex virus type 2.

Monoclonal antibodies secreted by six hybridomas and recognizing antigenic sites on glycoproteins gC, gAB, gD, gE, and gF of herpes simplex virus type 2 were examined for their ability to protect BALB/c mice from lethal infection by the virus. Administration of monoclonal antibodies to individual glycoproteins intraperitoneally 3 h before footpad challenge with 10 times the 50% lethal dose of virus protected between 35 and 75% of the mice, except for one of two monoclonal antibodies recognizing antigens on gC. The antibodies did not neutralize virus in vitro and protected A/J mice deficient in the fifth component of complement as efficiently as complement-sufficient BALB/c mice. A good correlation was found between protection and titers of monoclonal antibodies assessed by antibody-dependent cell-mediated cytolysis. The results indicate that any of the glycoproteins can serve as antigens for a protective immune response. In addition, the data are compatible with protection being mediated by an antibody-dependent cell-mediated cytolysis mechanism.

Animals↗
PubMed1982

Identification and typing of herpes simplex viruses with monoclonal antibodies.

Monoclonal antibodies which reacted with type-specific antigens of herpes simplex virus type 2 or with antigens shared by herpes simplex virus types 1 and 2 were used in an indirect immunofluorescence assay to type virus isolates and to detect viral antigens in cells obtained from herpetic lesions. Complete concordance was obtained for 42 isolates typed by endonuclease restriction analysis of viral DNA and by indirect immunofluorescence with monoclonal antibodies. Examination of a limited number of ulcerative lesions revealed that indirect immunofluorescence and virus isolation were comparable in detecting herpes simplex virus. The results indicate that monoclonal antibodies can be used to accurately identify and type isolates of herpes simplex virus.

Animals↗
PubMed1982

Glycoproteins of herpes simplex virus type 2 as defined by monoclonal antibodies.

We used monoclonal antibodies reacting with glycoproteins specified by herpes simplex virus type 2 (HSV-2) to characterize the individual antigens in terms of structure, processing, and kinetics of synthesis in BHK or Vero infected cells. Our results provided a direct demonstration of the structural identity of the gA and gB proteins of HSV-2 as well as confirmation of the existence of type-specific and type-common domains within the gD molecule. They also show that, with the exception of gC, processing of the viral glycoproteins differs to some extent in Vero and BHK infected cells, possibly as a result of different efficiency of glycosylation or different processing of underglycosylated and unglycosylated products in the two cell types. Finally, we showed that individual HSV-2 glycoproteins are synthesized at greatly different times during the infectious cycle, possibly in response to their different roles in virus replication and assembly.

Animals↗
PubMed1981

Production of hybrid cell lines secreting antibodies to herpes simplex virus type 2.

Following different immunization schedules we have produced 102 myeloma--spleen cell hybrid lines (30.8% of the total) secreting antibodies to HSV-2 infected cells. The highest yield of hybrids was derived from fusion of myeloma cells with spleen cells from mice sensitized by footpad injection of formalin-inactivated virus and boosted intravenously with the same antigen. To date, twelve of the antibody-producing hybrids have been cloned by limiting dilutions to generate over 100 monoclonal lines reacting specifically with HSV-infected but not with mock-infected cells. Several hybrid lines have also been injected into mice to generate tumors and high titers of anti-HSV-specific antibodies have been detected in ascitic fluids. All of the hybrids so far tested have retained the capacity to secrete anti-HSV antibodies after long-term in culture or repeated passages through mice. Antibodies reacting with cytoplasmic or nuclear antigens in infected cells as well as type-specific and type common antibodies have been detected.

Animals↗
PubMed1981

Monoclonal antibodies to two glycoproteins of herpes simplex virus type 2.

Monoclonal antibodies to herpes simplex virus type 2 were found to precipitate different numbers of radiolabeled polypeptides from lysates of virus-infected cells. Antibodies directed against two viral glycoproteins were characterized. Antibodies from hybridoma 17 alpha A2 precipitated a 60,000-molecular-weight polypeptide which chased into a 66,000- and 79,000-molecular-weight polypeptide. All three polypeptides labeled in the presence of [3H]glucosamine and had similar tryptic digest maps. The 60,000-molecular-weight polypeptide also chased into a 31,000-molecular-weight species which did not label with [3H]glucosamine. Antibodies from hybridoma 17 beta C2 precipitated a 50,000-molecular-weight polypeptide which chased into a 56,000- and 80,000-molecular weight polypeptide. These polypeptides also shared a similar tryptic digest map and labeled with [3H]glucosamine. Both monoclonal antibodies were herpes simplex virus type 2 specific. The viral proteins precipitated by 17 alpha A2 antibodies had characteristics similar to those reported for glycoprotein E, whereas the proteins precipitated by 17 beta C2 antibodies appeared to represent a glycoprotein not previously described. This glycoprotein should be tentatively designated glycoprotein F.

Antibodies, Monoclonal↗
PubMed1980

Elution of herpes simplex virus-specific cytotoxic antibodies from squamous cell carcinoma of uterine cervix.

There is evidence that carcinoma of the cervix uteri is associated with infection with herpes simplex virus type 2 (HSV-2), and although indirect evidence suggests an aetiological relationship, this remains controversial. One facet of the problem is that complement-dependent cytotoxic antibodies is HSV-2-infected cells have been undetectable or found only in low titre in sera from patients with progressive cervical cancer whereas higher titres have been found where cervical lesions are less advanced. Indeed, cytotoxic antibody titres have been found to rise during the follow-up period after successful treatment. Absorption of these antibodies by the tumour cells has been proposed as a possible reason for low HSV-2 cytolytic reactivity in patients with progressing cervical cancer. This explanation assumes the presence of HSV-2-specific antigen(s) on the tumour cells. We now provide support ffor this assumption with evidence that absorbed HSV-2-specific antibodies can be eluted from cervical cancer tissue.

Antibodies, Viral↗
PubMed1980

Immune response in rabbits to surface components of extracellular and intracellular forms of vaccinia virus.

The development of cellular as well as humoral immune response to extracellular and intracellular forms of vaccinia virus (ECV and ICV, respectively) and their surface antigens were studied in rabbits. Direct lymphocyte cytotoxicity and peripheral blood leukocyte migration inhibition tests were used to measure cell-mediated immune response, while neutralizing and hemagglutination-inhibiting antibodies were assayed for measuring humoral immune response. Direct cytotoxicity of lymphocytes from rabbits immunized with ECV or its surface proteins was demonstrable by day 7 after immunization, and by the end of week 3 it almost declined to pre-immunization levels. Inoculation with ICV or its surface proteins failed to induce lymphocyte cytotoxicity. In contrast, migration inhibition of peripheral blood leukocytes from rabbits immunized with ECV, ICV, or their surface proteins was observed with homologous antigens. However, leukocytes from rabbits immunized with ECV or its surface proteins also showed migration inhibition in the presence of ICV. Similarly, in the humoral immune response, neutralizing antibodies were produced against homologous as well as heterologous forms of virus despite immunization with purified preparations of ECV, ICV, or their surface proteins. Adsorption with purified ICV preparations abolished the neutralizing activity of these antisera against heterologous forms of virus. Hemagglutination-inhibiting antibodies, on the other hand, were produced only after immunization with ECV or its surface proteins. In addition, antibody-dependent cell-mediated cytotoxicity was employed to detect specific antibody response after immunization of rabbits with live virus, ECV, and ICV. Antisera raised against ECV or live virus supported antibody-dependent cell-mediated cytotoxicity, whereas ICV-antiserum failed to do so. The antibody activity present in the former antisera was abolished by absorption with cell membranes from vaccinia-infected cells but not with purified ICV. The data suggest that immunization with inactivated ECV seems to bring about interaction between host immune response (cellular and humoral) and virus-infected cells, which may, perhaps, be necessary for protection against pox virus infection. A similar interaction is unlikely to occur after immunization with inactivated ICV.

Animals↗
PubMed1979

Use of the 51chromium release test to demonstrate antigenic differences between extracellular and intracellular forms of vaccinia virus.

Complement-dependent antibody lysis of vaccinia-infected cells was examined to demonstrate the antigenic differences between extracellular (ECV) and intracellular (ICV) forms of vaccinia virus. Cytolytic antibodies present in the antisera raised against ECV or live virus (LV) were completely removed by absorption with infected cell membranes or purified ECV but not with purified ICV. Absorption with infected cell membranes also abolished the neutralizing activity of ECV and LV antisera against ECV. On the other hand, antiserum against ICV did not contain cytolytic antibodies against vaccinia-infected cells, even though its neutralizing antibody titre against ICV was high. Moreover, both ECV and ICV antisera neutralized a small proportion of the heterologous form of virus, despite using purified preparations of ECV and ICV, respectively, for raising these antisera in rabbits. In contrast, the 51Cr release test only detected the antibodies against ECV and thus can be used to differentiate between the antibody activity of a serum against ECV and ICV.

Animals↗
PubMed1979

Rehabilitation of Caisson's disease with spinal cord involvement.

Fifteen cases of Caisson's Disease or Decompression Sickness with spinal cord involvement treated at the Department of Rehabilitation Tan Tock Seng Hospital, from 1973 to 1978 are described. All the cases had bladder and bowel function involvement. Five cases developed bone complications, one of whom was referred to us primarily for rehabilitation after he had an operation for collapsed right femoral head which occurred two years after the incident.

Adult↗
PubMed1979

Rehabilitation of traumatic spinal cord lesions--results of 145 cases treated between 1973 and 1977.

An analysis of 145 traumatic spinal cord lesions admitted to the Department of Rehabilitation Medicine, Tan Tock Seng Hospital, between 1973 and 1977 is made. The annual incidence based on this figure and on a population of 2.2 million was 16.3 per million population. 68% of the cases were within the employable age group of 15 to 45 years. 40% of them were due to industrial accidents, 36% from road traffic accidents and 24% resulted from other causes like domestic accidents, sports mishaps and criminal violence. An analysis of the site of lesion shows that 71 cases had lesions at the cervical level, 50 at the thoracic lumbar region, 9 at the upper thoracic region and 15 at the lumbar region. After a course of rehabilitaion 66% were able to walk either independently or with some form of aids, 27% were wheelchair-bound and the rest were bedridden at time of discharge. In self-care activities 79% were independent, 15% were partially dependent and the rest totally dependent after rehabilitation.

Accidents, Home↗
PubMed1979

Circulating immune complexes in carcinoma of uterine cervix.

Circulating immune complexes were determined in the sera of forty-eight patients wital status by inhibition of rheumatoid factor (RF) maediated agglutination of IgG coated latex particles. The inhibitory activity was present in 63% of the sera from cervical cancer patients but only 13% of sera from control women contained this activity. Similarly, anticomplementary activity suggestive of the presence of immune complexes was present in 71% of sera from cancer patients and 13% of sera from control women. The incidence as well as the levels of immune complexes (IC) were higher in sera of patients with advanced stages of cancer as compared to those with Stage I cervical cancer. In addition, 95% of sera from cervical cancer patients had cryoblobulins, whereas only 20.8% sera from matched controls were positive for cryoprecipitates. All the cryoglobulins contained IgG type of immunoglobulin except one which had IgA immunoglobulins also. The complexes have not been characterized with regard to the nature of the antigen(s) present.

Antigen-Antibody Complex↗