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Biomedical subjects

A Ahmed

Publications and source records attributed to A Ahmed.

At least 55 records · Page 3Linked to original sources
PubMed1978

Vibriocidal antibody titer rise after rectal or anal administration of Vibrio cholerae in dogs.

In many developing countries and ablution with surface water is a daily habit. This water is heavily contaminated with microbes, raising the possibility that and contamination may lead to immune responses. This hypothesis was experimentally tested in 21 dogs by anal or rectal application of Vibrio cholerae suspension V. cholerae was recovered from rectal swab cultures for a mean of one day after rectal contamination and 2.5 days after anal application (P less than .02). Significant increases occurred in the geometric mean titer of serum vibriocidal antibody; this suggests the need for study of the possible role of anal ablution in maintaining serum vibriocidal antibody levels in endemic cholera areas.

Anal Canal↗
PubMed1978

Immunobiology of congenitally athymic-asplenic mice.

Congenitally athymic-asplenic mice on an outbred N:NIH(S) background were produced by the mating of nude by hereditarily asplenic (Dh/+)mice. Athymic-asplenic mice survive for up to 9 months, under specific pathogen free conditions, with no evidence for increased risk of spontaneous neoplasia. Although lymphocyte surface markers and sera immunoglobulin levels of athymic-asplenic mice are similar to their nude and asplenic littermates, there are a number of significant differences. In particular, levels of sera IgA are higher than nude, but lower than either nu/+ or Dh/+ mice, related perhaps to the increased histiocytic engorgement of Peyer's patches. Athymic-asplenic mice have normal haematocrit, haemoglobin, and reticulocyte counts, but are markedly leucopenic, have a thrombocytosis and an increased number of bone marrow CFU-C. As expected, the response of the athymic-asplenic mice to the T cell mitogen PHA is markedly reduced. However, levels of Thy 1.2 bearing cells, while reduced compared to either nu/+ or Dh/+ littermates, are significantly higher than nude mice in both Peyer's patches and lymph nodes. Further, they, like their nude littermates, fail to respond to sheep red blood cell immunization. Nonetheless, athymic-asplenic mice appear more immunologically compromised than nude mice. Indeed, there is an elevated rate of growth and a lower inoculated cell threshold needed for successful transplantation of a human malignant melanoma. Finally, there was no evidence for auto-antibody production in mice up to 9 months of age. Congenitally athymic-asplenic mice can be used for a variety of studies in which other immunologically deprived mouse mutants are desired.

Animals↗
PubMed1978

Studies on the transfer of protective immunity with lymphoid cells from mice immune to malaria sporozoites.

In an effort to understand the mechanisms involved in the protective immunity to malarial sporozoites, an A/J mouse/Plasmodium berghei model was studied. Protective immunity could consistently be adoptively transferred only by using sublethal irradiation of recipients (500 R); a spleen equivalent (100 X 10(6))of donor cells from immune syngeneic mice; and a small booster immunization (1 X 10(4)) of recipients with irradiation-attenuated sporozoites. Recipient animals treated in this manner were protected from lethal challenge with 1 X 10(4) nonattenuated sporozoites. Immune and nonimmune serum and spleen cells from nonimmune animals did not protect recipient mice. Fewer immune spleen cells (50 X 10(6)) protected some recipients. In vitro treatment of immune spleen cells with anti-theta sera and complement abolished their ability to transfer protection. This preliminary study suggests that protective sporozoite immunity can be transferred with cells, and that it is T cell dependent.

Animals↗
PubMed1977

B-lymphocyte Fc receptor-associated non-H-2 antigens are determined by a single polymorphic locus which is linked to the Mls locus.

Certain non-H-2 alloantigens are associated with murine B-lymphocyte Fc receptors in that pretreatment of spleen cells with alloantibodies against these antigens inhibited binding of Ig complexes to B-cell Fc receptors. This inhibition was specific in that: (a) as has been shown previously, the Fc portion of the alloantibody was not required to produce inhibition; and (b) antibodies against some non-H-2 antigens but not antibodies against others (including some that were expressed on B cells) caused such inhibition. Backcross experiments revealed that the B-cell Fc receptor-associated non-H-2 antigens were determined by the gene(s) of a single background locus in each of the three strains tested (A/J, B10, and CBA/J). This locus was poly-morphic in that at least four different B-cell Fc receptor:associated non-H-2 antigens were identified (one each in the A/J, B10, and CBAJJ and one antigen shared or crossreactive between the B10 and CBA/J). These antigens were primarily but not exclusively expressed on B lymphocytes as determined by immunofluorescence studies, and on the basis of capping experiments they did not appear to be identical to B-cell Fc receptors. Linkage studies revealed that the locus which determined these antigens was not linked to the albino locus nor the heavy chain allotype locus and expression was neither sex-limited nor an X-linked recessive trait. However, this locus was closely linked but not identical to the Mls locus (apparent recombination frequency 6.8 percent). Thus, two closely linked non-H-2 loci both determine the expression of antigens which have characteristics similar to Ia antigens. One locus is polymorphic and determines the expression of antigens which are primarily expressed on B cells and are specifically associated with the Fc receptors of these cells. The other (Mls locus) determines antigens which are stimulatory in mixed lymphocyte cultures. These observations suggest that there may be a second gene complex which is the analogue of the I region of the H-2 complex.

Animals↗
PubMed1977

Theta-sensitive cell and erythropoiesis: identification of a defect in W/Wv anemic mice.

Nonirradiated mice of the W/WV genotype were injected with normal (+/+) bone marrow cells that had been treated with antiserum to Thy 1.2 and complement (C'). Such bone marrow cells had no effect on the number of macroscopic colonies formed in the spleens of these mice, but did not cure the anemia. The addition of +/+ thymocytes to these bone marrow cells restored their ability to cure the anemia in W/WV mice. These data suggest that a theat-sensitive cell is required in the promotion of differentiation of murine hematopoietic stem cells into erythrocytes, and that there is a deficiency of such a cell in the W/WV mouse.

Anemia, Macrocytic↗
PubMed1977

B-lymphocyte heterogeneity: development and characterization of an alloantiserum which distinguishes B-lymphocyte differentiation alloantigens.

CBA/N mice and F1 male mice, which are hemizygous for the CBA/N X chromosome, have an immune defect which is associated with the absence (deficiency) of a subpopulation of mature or late developing B lymphocytes. This characteristic was utilized to develop an antiserum that was specific for this subclass of B cells. C57BL/L mice were immunized with DBA/2 spleen calls, and the resulting antisera was absorbed with lymphoid cells derived from immunologically abnormal (CBA/N female X DBA/2 male)F1 male mice. The absorbed antisera was cytotoxic for a subpopulation of lymphocytes that was present in the spleens of adult DBA/2 and (CBA/N female X DBA/2 male)F1 female mice. The cells killed by the absorbed antisera were Ig-bearing, complement receptor-bearing B lymphocytes, which had a low-to-intermediate density of total surface Ig. Moreover, the cells remaining after treatment of adult (CBA/N female X DBA/2 male)F1 female spleen cells with the absorbed antisera and C had a high ratio of surface IgM to IgD. The development of this cytotoxic alloantisera, which is specific for a late developing (mature) subpopulation of B lymphocytes, will allow the functional characterization of subclasses of B lymphocytes.

Animals↗
PubMed1977

The ultrastructure of tubular carcinoma of the breast.

The ultrastructure of four tubular carcinomas of the breast is described. The neoplastic tubules are single layered and lack a myo-epithelial component, an important feature in distinguishing tubular carcinoma from sclerosing adenosis. Numerous myo-fibroblasts are present in the stroma of all four tumours and, since cells of this type have been recorded only occasionally in the stroma of other types of breast carcinoma, it is suggested that they may be a characteristic feature of tubular carcinomas.

Breast Neoplasms↗
PubMed1977

Identification of the gal3 insertion in Escherichia coli AS IS2.

The gal3 mutation in Escherichia coli, located in the operator-promoter region of the gal operon, is identified as an IS2 insertion in the polar orientation I relative to the direction of transcription. This mutation, which may be considered the earliest example of a polar mutation caused by an IS insertion, is shown by heteroduplex analysis of phage lambdagal3 to be located about 170 base pairs from the promoter-proximal end of the chlD-pgl deletion in lambdagal8. It appears indistinguishable in position, sequence and orientation from the IS2 insertion carried by lambdagal8-490. The endpoints of the bacterial DNA segments in lambdagal3 and lambdagal8 are physically mapped in relation to attL.

Chromosome Aberrations↗
PubMed1977

Studies on non-H-2 linked lymphocyte activating determinants. I. Description of the cell type bearing the Mls product.

The non-H-2 linked, lymphocyte activating determinants (LADs), which are coded by the minor (histocompatibility) lymphocyte stimulating locus (Mls), were detected on B lymphocytes, but not on immunoglobuin (Ig) negative or on theta positive T lymphocytes. These determinants, like the complement receptor and surface IgD, develop late in neonatal life. Thus, the Mls coded LADs mark a population of B lymphocytes which are not present in the spleens of newborn to 2-week-old mice. Studies of B lymphocytes derived from the spleens of adult mice indicated that the cells bear the Mls coded LADs have a high density of surface Ig and possess the complement receptor.

Animals↗
PubMed1977

Murine B lymphocyte heterogeneity: distribution of complement receptor-bearing and minor lymphocyte-stimulating B lymphocytes among cells with different densities of total surface Ig and IgM.

The distribution of complement receptor-bearing (CR+) and minor lymphocyte-stimulating (Mls)-defined lymphocyte-activating determinants (LAD) among B lymphocytes with different densities of total surface immunoglobulin (sIg) and sIgM was determined. B lymphocytes that bore intermediate densities of sIg and low densities of sIgM had the highest frequency of CR+ cells and were the most active in expressing Mls-defined LAD. The distribution of these and other surface markers on B-lymphocyte subpopulations is discussed.

Animals↗