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Biomedical subjects

P Sultan

Publications and source records attributed to P Sultan.

18 recordsLinked to original sources
PubMed2006

Podophyllum hexandrum Offers Radioprotection by Modulating Free Radical Flux: Role of Aryl-Tetralin Lignans.

We have evaluated the effect of variation in aryl-tetralin lignans on the radioprotective properties of Podophyllum hexandrum. Two fractionated fractions of P. hexandrum [methanolic (S1) and chloroform fractions (S2)], with varying aryl-tetralin lignan content were utilized for the present study. The peroxyl ion scavenging potentials of S1 and S2 were found to be comparable [i.e. 45.88% (S1) and 41% (S2)] after a 48 h interval in a time-dependent study, whereas in a 2 h study, S2 exhibited significant (P < 0.05) antioxidant activity in different metal ion + flux states. In the aqueous phase, S2 exhibited non-site-specific reactive oxygen species scavenging activity, i.e. 73.12% inhibition at 500 mug ml(-1). S1 exhibited 58.40 +/- 0.8% inhibition (at 0.025 mug ml(-1)) of the formation of reactive nitrite radicals, comparable to S2 (52.45 +/- 0.825%), and also showed 45.01% site-specific activity (1000 mug ml(-1)), along with significant (P < 0.05) electron donation potential (50-2000 mug ml(-1)) compared to S2. Such activities of S1 could be attributed to the significantly (P < 0.05) higher levels of podophyllotoxin beta-d-glucopyranoside (16.5 times) and demethyl podophyllotoxin glucoside (2.9 times) compared with S2. Together, these findings clearly prove that aryl-tetralin lignan content influences the radiation protective potential of the Podophyllum fractions to a great extent.

Journal Article↗
PubMed2005

Integrin function and signaling as pharmacological targets in cardiovascular diseases and in cancer.

The microenvironment is now considered as an important source of potential therapeutic targets in diverse pathologies. In cardiovascular diseases and in cancer, common processes involving stromal remodeling, cell invasion, and angiogenesis can promote progression of the pathology. At each step of the pathogenesis, cell adhesion needs to be modulated to allow adaptation of cell survival/motility/proliferation functions to the microenvironment. Among adhesion receptors, integrins, responsible for cell/matrix or cell/cell interactions, play a key role in the cellular responses. Moreover, their engagement conditions the sensitivity to apoptosis induced by therapeutic drugs. Targeting of the extracellular side of integrins in order to modulate their adhesive functions is under development and has reached clinical indications. However, improvement of oral availability and of cell signaling control is required in the future. Targeting of the extracellular or the intracellular key proteins involved in integrin-dependent signaling pathway seems promising. Yet, although some common key enzyme inhibitors are under development, a better knowledge of the specificity of integrin activation and interaction with partners upon pathogenesis is of major importance in envisaging the antagonism of integrin-linked signals as a therapeutic tool alone or in association with other therapies.

Cardiovascular Diseases↗
PubMed1998

Dermal microvascular injury in the human peripheral blood lymphocyte reconstituted-severe combined immunodeficient (HuPBL-SCID) mouse/skin allograft model is T cell mediated and inhibited by a combination of cyclosporine and rapamycin.

We have analyzed the mechanism of human endothelial injury in a human peripheral blood lymphocyte-severe combined immunodeficient (huPBL-SCID) mouse/human skin graft model of allograft injury and examined the effect of immunosuppressive drugs on this process. In this model, split-thickness human skin containing the superficial dermal microvessels was grafted onto immunodeficient C.B-17 SCID or SCID/beige mice and allowed to heal. Human peripheral blood mononuclear cells (PBMCs) allogeneic to the skin, when subsequently introduced by intraperitoneal injection, caused destruction of the human dermal microvasculature by day 16, evident as endothelial cell sloughing and thrombosis. In the same specimens, mouse microvessels that invaded the human skin graft were uninjured. Human microvascular cell injury was accompanied by a mononuclear cell infiltrate consisting of approximately equal numbers of human CD4+ and CD8+ T cells, some of which contained perforin-positive granules. We found no evidence of human natural killer cells and noted occasional human, but not mouse, macrophages at a frequency indistinguishable from that resident in skin on animals not receiving human PBMCs. These human T cell infiltrates did not extend into adjacent mouse skin. Human immunoglobulin G antibody was detected in the blood and was diffusely present throughout mouse and human tissues in SCID mice receiving PBMCs. Mouse C3 was detected on human dermal vessels in both unreconstituted control animals and those that received PBMCs. Blood and tissues from mice injected with PBMCs depleted of B cells showed no human immunoglobulin, but circulating CD3+ cells were detected by flow cytometry at levels comparable with those of animals receiving whole PBMCs. Significantly, skin graft infiltration by human T cells and human dermal microvascular injury were equivalent in the B cell-depleted and whole-PBMC-reconstituted mice. Mice inoculated with PBMCs depleted of CD8+ T cells developed microvascular injury and infiltrates containing perforin-expressing CD4+ T cells. These data suggested a cytolytic T cell-dependent mechanism of microvessel injury. We then tested the ability of T cell immunosuppressants, cyclosporine and rapamycin, to attenuate vessel damage. Neither cyclosporine nor rapamycin alone effectively reduced either mononuclear cell infiltration or vascular injury. However, a combination of the two agents reduced both parameters. We conclude that the huPBL-SCID/skin allograft model may be used both to study cytolytic T cell-mediated rejection and to test the effect of immunosuppressive drug strategies in vivo in a small-animal model of human immune responses.

Animals↗
PubMed1997

Pig but not human interferon-gamma initiates human cell-mediated rejection of pig tissue in vivo.

Split-thickness pig skin was transplanted on severe combined immunodeficient mice so that pig dermal microvessels spontaneously inosculated with mouse microvessels and functioned to perfuse the grafts. Pig endothelial cells in the healed grafts constitutively expressed class I and class II major histocompatibility complex molecules. Major histocompatibility complex molecule expression could be further increased by intradermal injection of pig interferon-gamma (IFN-gamma) but not human IFN-gamma or tumor necrosis factor. Grafts injected with pig IFN-gamma also developed a sparse infiltrate of mouse neutrophils and eosinophils without evidence of injury. Introduction of human peripheral blood mononuclear cells into the animals by intraperitoneal inoculation resulted in sparse perivascular mononuclear cell infiltrates in the grafts confined to the pig dermis. Injection of pig skin grafts on mice that received human peripheral blood mononuclear cells with pig IFN-gamma (but not human IFN-gamma or heat-inactivated pig IFN-gamma) induced human CD4(+) and CD8(+) T cells and macrophages to more extensively infiltrate the pig skin grafts and injure pig dermal microvessels. These findings suggest that human T cell-mediated rejection of xenotransplanted pig organs may be prevented if cellular sources of pig interferon (e.g., passenger lymphocytes) are eliminated from the graft.

Animals↗
PubMed1997

Blockade of CD2-LFA-3 interactions protects human skin allografts in immunodeficient mouse/human chimeras.

A human skin allograft injury model in immunodeficient mice, engrafted with human peripheral blood mononuclear cells from a different donor, has been used to test whether reagents that block human T cell CD2 interactions with its principal ligand, LFA-3 (CD58), can inhibit immune reactions in vivo. In this model, human skin grafts show a reproducible pattern of progressive human T-cell infiltration and human graft microvascular injury that resembles human first-set skin graft rejection. Murine Mab to human LFA-3 or human LFA-3-IgG1 fusion protein, but not isotype-matched control antibodies, each markedly protected skin grafts from leukocyte infiltration and injury. These data provide the first evidence that LFA-3 functions in vivo and establish the ability of this new model to test human-specific immune modulators.

Animals↗
PubMed1995

Variation in the number, location and size of synaptic vesicles provides an anatomical basis for the nonuniform probability of release at hippocampal CA1 synapses.

Synaptic vesicles, synaptic clefts and postsynaptic areas were measured in three dimensional reconstructions at representative axonal boutons in hippocampal area CA1. Both docked and non-docked vesicles were counted and measured. Small boutons on thin spines had about 2-6 docked vesicles from a pool of more than 200 vesicles. Medium-sized boutons on medium-sized mushroom-shaped dendritic spines contained about 13-16 docked vesicles from a pool of more than 450 vesicles. A large bouton synapsing with a large mushroom-shaped dendritic spine had two clusters of vesicles totaling more than 1000 vesicles. The postsynaptic density was segmented into two discrete zones under the two clusters of vesicles and 36 docked vesicles were distributed over its surfaces. Two multiple-synapse boutons contained more than 500 vesicles with 2-12 docked vesicles observed at each of the two postsynaptic densities on each bouton. This nonuniform number of docked vesicles provides an anatomical basis for the non-uniform probability of release that occurs across hippocampal synapses of different sizes. In addition, the volume of each synaptic vesicle was determined to be 0.4-5.2% of the total volume of the reconstructed synaptic clefts into which they presumably release their contents. However, since each vesicle contains more than 10 times the concentration of glutamate needed to saturate the postsynaptic receptors, these data also support the hypothesis that release a single synaptic vesicle will activate all of the postsynaptic receptors.

Animals↗
PubMed1992

Nucleotide sequence of endothelin-1 cDNA from rabbit endothelial cells.

A cDNA encoding rabbit endothelin-1 (ET-1) was isolated by plaque hybridization from a rabbit inferior vena caval endothelial cell lambda gt11 cDNA library using human ET-1 cDNA as the hybridization probe. DNA sequence analysis indicates that mature 21 amino acid rabbit ET-1 is derived from a 202 amino acid precursor, via a 39 amino acid intermediate 'big' ET-1.

Amino Acid Sequence↗
PubMed1991

Gene structure, chromosomal location, and basis for alternative mRNA splicing of the human VCAM1 gene.

Vascular cell adhesion molecule 1 (VCAM-1) is a cell surface glycoprotein adhesive for certain blood leukocytes and tumor cells, which is expressed by activated endothelium in a variety of pathologic conditions including atherosclerosis. Genomic clones encoding the VCAM1 gene were isolated and the organization of the gene was determined. The gene, which is present in a single copy in the human genome, contains 9 exons spanning approximately 25 kilobases of DNA. Exons 2-8 contain C2 or H-type immunoglobulin domains. At least two different VCAM-1 precursors can be generated from the human gene as a result of alternative mRNA splicing events, which include or exclude exon 5. A consensus TATAA element is located upstream of the transcriptional start site. The VCAM1 promoter contains consensus binding sites for NF-kappa B, the GATA family of transcription factors, as well as an AP1 site. The VCAM1 gene was assigned to the 1p31-32 region of chromosome 1 based on the analysis of human-mouse hybrid cell lines and in situ hybridization. Structural analysis of the human VCAM1 gene provides the basis for alternative mRNA splicing and an initial approach to elucidating the regulation of VCAM-1 expression.

Amino Acid Sequence↗
PubMed1991

Structure of the murine c-sis proto-oncogene (Sis, PDGFB) encoding the B chain of platelet-derived growth factor.

The murine proto-oncogene c-sis (Sis, PDGFB), encoding the B chain of platelet-derived growth factor, has been cloned. Its structure, with seven exons spanning approximately 20 kb, closely resembles that of the human and feline homologs. The predicted amino acid sequence of murine PDGF-B has residues 89% identical to those of human PDGF-B. A noncoding region at the start of exon 7, which is deleted by alternative splicing during the generation of the viral v-sis oncogene, is highly conserved in human, mouse, and cat and may represent an important regulatory element.

Amino Acid Sequence↗
PubMed1991

Alternative splicing of human VCAM-1 in activated vascular endothelium.

Vascular cell adhesion molecule 1 (VCAM-1)/inducible cell adhesion molecule 110 is a mononuclear leukocyte-selective adhesion molecule, expressed on vascular endothelium following activation by certain cytokines or endotoxin. This inducible transmembrane protein and member of the immunoglobulin gene superfamily was previously reported to contain six immunoglobulinlike domains. Using the polymerase chain reaction, a VCAM-1 cDNA was obtained from mRNA of interleukin-1 (IL-1)-treated cultured human umbilical vein endothelial cells (HUVEC). The cDNA clone contained an additional 276 base-pair (bp) domain, located between domains 3 and 4. This new domain is most homologous to the existing N-terminal domain (domain 1). The internal 276-bp region is encoded by a single exon of the human VCAM-1 gene, indicating that the two forms of mRNA arise by alternative splicing. Both forms of VCAM-1 mRNA were detected by polymerase chain reaction in IL-1-stimulated HUVEC, although the seven-domain form appeared predominant. On the surface of HUVEC only a 110-kd polypeptide, consistent with the seven-immunoglobulinlike domain form of VCAM-1, was detectable by immunoprecipitation. Alternative splicing of the VCAM-1 gene in cytokine-activated endothelium may generate functionally distinct cell-surface adhesion molecules.

Amino Acid Sequence↗
PubMed1985

[The impacted canine. Review of 212 cases. General principles of treatment].

The authors have studied the localization, the functional and radiological signs, the complications, the etiologies and the treatment, according to 212 cases of impacted canines. The upper impacted canines are more frequent and women are more concerned, it can be unilateral as well as bilateral. If the mentioned etiologies are debatable and if the functional signs are poor, the complications are frequent: infectious, mechanical, tumorous or algesic. The therapeutic approach should primarily consider the evolutive potential of the tooth. As a matter of fact, before undergoing any surgical or any complicated surgical orthodontic treatment, the result of our study shows that the eventual absence of any ankylosis image has to be precised on successive profile headfilms taken with an interval of 6 to 12 months. If any evolution is seen, it would be enough to remove the mucous obstacle and then bring the tooth to a normal position by some mechanical means. In the adverse case, the prognosis won't be favorable and leads to either abstention or a dubious therapeutics.

Adolescent↗