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Biomedical subjects

Sanjeev Gupta

Publications and source records attributed to Sanjeev Gupta.

At least 37 records · Page 2Linked to original sources
PubMed2005

Contact allergies to cosmetics: testing with 52 cosmetic ingredients and personal products.

Fifty patients of both sexes with clinically suspected cosmetic dermatitis were subjected to patch testing with a cosmetic and fragrance series, approved by the Contact and Occupational Dermatosis Forum of India (CODFI), and with selected allergens from the Indian Standard Series (ISS). Most of these patients were young adults between 10-29 years; the mean age was 27.5 years. The majority of the patients had cosmetic dermatitis of <1 year duration (68%). The occupational profiles of the patients included students (46%), housewives (18%), teachers (10%) and laborers (4%). A miscellaneous group, comprised of tailors, farmers, staff nurses, beauticians, jewellers and engineers, accounted for the remaining 22%. The most commonly involved site was the face, followed by the forehead, neck and scalp. Patch testing of these patients revealed that, out of the 50 subjects tested, thirty-three (66%) reacted to one or more allergens. Fragrance components were the most common offending allergen (51.5%) followed by preservatives (39.3%), paraphenylenediamine (PPD) (21.2%), and cetrimide and tertiary butyl hydroquinone (12.1% each), in descending order of frequency. Hence, patch testing, with the standard series supplemented by personal cosmetics; should be considered for patients with cosmetic dermatitis to determine the offending allergen so as to avoid further contact with that allergen.

Adolescent↗
PubMed2005

Embryonic mouse STO cell-derived xenografts express hepatocytic functions in the livers of nonimmunosuppressed adult rats.

Cells derived from embryonic mouse STO cell lines differentiate into hepatocytes when transplanted into the livers of nonimmunosuppressed dipeptidylpeptidase IV (DPPIV)-negative F344 rats. Within 1 day after intrasplenic injection, donor cells moved rapidly into the liver and were found in intravascular and perivascular sites; by 1 month, they were intrasinusoidal and also integrated into hepatic plates with approximately 2% efficiency and formed conjoint bile canaliculi. Neither donor cell proliferation nor host inflammatory responses were observed during this time. Detection of intrahepatic mouse COX1 mitochondrial DNA and mouse albumin mRNA in recipient rats indicated survival and differentiation of donor cells for at least 3 months. Mouse COX1 targets were also detected intrahepatically 4-9 weeks after STO cell injection into nonimmunosuppressed wild-type rats. In contrast to STO-transplanted rats, mouse DNA or RNA was not detectable in untreated or mock-transplanted rats or in rats injected with donor cell DNA. In cultured STO donor cells, DPPIV and glucose-6-phosphatase activities were observed in small clusters; in contrast, mouse major histocompatibility complex class I H-2Kq, H-2Dq, and H-2Lq and class II I-Aq markers were undetectable in vitro before or after interferon gamma treatment. Together with H-2K allele typing, which confirmed the Swiss mouse origin of the donor cells, these observations indicate that mouse-derived STO cell lines can differentiate along hepatocytic lineage and engraft into rat liver across major histocompatibility barriers.

Animals↗
PubMed2005

Regulation of hepatobiliary transport activity and noninvasive identification of cytokine-dependent liver inflammation.

UNLABELLED: Many diseases are associated with cytokine release after inflammatory infiltration, which perturbs organ function. Radioligands capable of noninvasive tracking to assess the integrity of specific biochemical pathways offer potent ways to establish such perturbing mechanisms. METHODS: To demonstrate regulation of hepatobiliary transport in disease, we used (99m)Tc-mebrofenin in a carbon tetrachloride-induced liver injury model in Fischer 344 rats. Healthy rats served as control animals. Image analysis was used to determine (99m)Tc-mebrofenin handling. Liver tests and histologic analysis were used for grading liver injury and hepatic fibrosis. To address the role of inflammatory cytokines, we used in vitro assays with (99m)Tc-mebrofenin-loaded primary rat hepatocytes. RESULTS: In healthy rats, (99m)Tc-mebrofenin was promptly excreted, and after 1 h only 20% +/- 5% (mean +/- SD) of peak (99m)Tc-mebrofenin activity remained in the liver. In contrast, rats treated with carbon tetrachloride for 1 or 3 mo showed 84% +/- 5% and 80% +/- 7% (mean +/- SD), respectively, of peak (99m)Tc-mebrofenin activity in the liver after 1 h (P < 0.001). Abnormal (99m)Tc-mebrofenin transport was associated with necroinflammatory activity and not hepatic fibrosis. This was examined directly in animals, where withdrawal of carbon tetrachloride for 2 wk after significant liver injury produced loss of inflammatory activity without affecting hepatic fibrosis. In this situation, (99m)Tc-mebrofenin transport returned to normal, indicating a central role of inflammatory activity in this process. In vitro assays showed impairment in (99m)Tc-mebrofenin excretion after incubation of cultured hepatocytes with interleukin-6 and further impairment with interleukin-6 plus tumor necrosis factor-alpha. CONCLUSION: The findings indicate that inflammatory cytokines regulate (99m)Tc-mebrofenin transport. This cytokine-mediated process establishes a paradigm for identifying and monitoring organ inflammation, including in viral or alcoholic hepatitis, fatty liver disease, allograft rejection, and responses to gene therapy vectors.

Aniline Compounds↗
PubMed2004

Regulation of HAX-1 anti-apoptotic protein by Omi/HtrA2 protease during cell death.

Omi/HtrA2 is a nuclear-encoded mitochondrial serine protease that has a pro-apoptotic function in mammalian cells. Upon induction of apoptosis, Omi translocates to the cytoplasm and participates in caspase-dependent apoptosis by binding and degrading inhibitor of apoptosis proteins. Omi can also initiate caspase-independent apoptosis in a process that relies entirely on its ability to function as an active protease. To investigate the mechanism of Omi-induced apoptosis, we set out to isolate novel substrates that are cleaved by this protease. We identified HS1-associated protein X-1 (HAX-1), a mitochondrial anti-apoptotic protein, as a specific Omi interactor that is cleaved by Omi both in vitro and in vivo. HAX-1 degradation follows Omi activation in cells treated with various apoptotic stimuli. Using a specific inhibitor of Omi, HAX-1 degradation is prevented and cell death is reduced. Cleavage of HAX-1 was not observed in a cell line derived from motor neuron degeneration 2 mice that carry a mutated form of Omi that affects its proteolytic activity. Degradation of HAX-1 is an early event in the apoptotic process and occurs while Omi is still confined in the mitochondria. Our results suggest that Omi has a unique pro-apoptotic function in mitochondria that involves removal of the HAX-1 anti-apoptotic protein. This function is distinct from its ability to activate caspase-dependent apoptosis in the cytoplasm by degrading inhibitor of apoptosis proteins.

Adaptor Proteins, Signal Transducing↗
PubMed2004

The C-terminal tail of presenilin regulates Omi/HtrA2 protease activity.

Presenilin mutations are responsible for most cases of autosomal dominant inherited forms of early onset Alzheimer disease. Presenilins play an important role in amyloid beta-precursor processing, NOTCH receptor signaling, and apoptosis. However, the molecular mechanisms by which presenilins regulate apoptosis are not fully understood. Here, we report that presenilin-1 (PS1) regulates the proteolytic activity of the serine protease Omi/HtrA2 through direct interaction with its regulatory PDZ domain. We show that a peptide corresponding to the cytoplasmic C-terminal tail of PS1 dramatically increases the proteolytic activity of Omi/HtrA2 toward the inhibitor of apoptosis proteins and beta-casein and induces cell death in an Omi/HtrA2-dependent manner. Consistent with these results, ectopic expression of full-length PS1, but not PS1 lacking the C-terminal PDZ binding motif, potentiated Omi/HtrA2-induced cell death. Our results suggest that the C terminus of PS1 is an activation peptide ligand for the PDZ domain of Omi/HtrA2 and may regulate the protease activity of Omi/HtrA2 after its release from the mitochondria during apoptosis. This mechanism of Omi/HtrA2 activation is similar to the mechanism of activation of the related bacterial DegS protease by the outer-membrane porins.

Amino Acid Sequence↗
PubMed2004

Isolated small intestinal segments support auxiliary livers with maintenance of hepatic functions.

We determine here the functional integrity of auxiliary livers in containers fashioned from the small intestine. Liver microfragments from dipeptidyl peptidase 4 (DPP4)-deficient rats were transplanted into syngeneic normal animals with isolated intestinal segments characterized by mucosal denudation but intact vascular supply. Transplanted liver fragments were restored to confluent tissue with normal hepatic architecture and development of DPP4-positive vessels, indicating angiogenesis and revascularization. Auxiliary liver units expressed multiple hepatotrophic and angiogenic genes, and transplanted tissues remained intact for up to the 6-week duration of the studies with neither ischemic injury nor significant hepatocellular proliferation. Hepatic metabolic, transport and synthetic functions were preserved in auxiliary livers, including uptake and biliary excretion of (99m)Tc-mebrofenin in syngeneic recipients of liver from F344 rats, as well as secretion of albumin in allografted Nagase analbuminemic rats. This ability to produce functionally competent auxiliary livers in vascularized intestinal segments offers therapeutic potential for liver disease and genetic deficiency.

Animals↗
PubMed2004

Emerging insights into liver-directed cell therapy for genetic and acquired disorders.

Treatment of acute or chronic liver diseases by cell transplantation is an attractive prospect because organ shortages greatly restrict liver transplantation. Moreover, a variety of genetic deficiency states affecting extrahepatic organs are amenable to liver-directed cell therapy. While the initial clinical experience with liver cell transplantation has been encouraging, further advances in several areas are necessary to improve these results. Insights into how engraftment and proliferation of transplanted cells may be modulated to obtain therapeutically effective masses of transplanted cells will be important in this pursuit. Studies of cell therapy in animal models of specific diseases have provided insights into the development of clinically relevant strategies for various disorders. Also, identification of suitable cell types, including stem/progenitor cells that could be expanded and manipulated in cell culture conditions, has begun to provide important new information for cell therapy. Similarly, advances in cryopreservation of cells and prevention of allograft rejection offer ways to accomplish cell therapy in an effective manner. Taken together, these advances indicate that liver-directed cell therapy will be well positioned in the near future to play significant roles in transplantation medicine.

Animals↗
PubMed2004

Role of contact allergens in pompholyx.

Fifty patients of both sexes with clinically suspected pompholyx were patch tested with the Indian Standard Patch Test Battery approved by the Contact & Occupational Dermatosis Forum of India (CODFI). Most of these patients were young adults between 20-39 years of age with a mean age of 30 years. The mean duration of symptoms was 4 years. The occupational profile of the patients included students (20%), housewives (16%), housewives engaged in farming (12%), labourers (12%), farmers (12%) and paramedical workers (6%). The miscellaneous group, including salesmen, teachers and photographers, accounted for the remaining 22%. The clinical patterns of presentation of pompholyx included cheiropompholyx (60%), cheiropompholyx and podopompholyx (36%) and podopompholyx alone (4%). Patch test analysis of these patients revealed that, out of the 50 subjects tested, 20 (40%) reacted to one or more allergens. Nickel sulphate was the commonest offending allergen (14%) followed by potassium dichromate and phenylene diamine and nitrofurazone (8% each), fragrance mix (6%) and cobalt chloride (4%), in descending order of frequency. Hence, patch testing may be considered for all patients with recurrent episodes of pompholyx as allergic contact dermatitis may be relatively common in such patients and the avoidance of offending allergens may be of substantial benefit to these patients.

Adolescent↗
PubMed2004

Analysis of the functional integrity of cryopreserved human liver cells including xenografting in immunodeficient mice to address suitability for clinical applications.

BACKGROUND: The availability of well-characterized human liver cell populations that can be frozen and thawed will be critical for cell therapy. We addressed whether human hepatocytes can recover after cryopreservation and engraft in immunodeficient mice. METHODS: We isolated cells from discarded human livers and studied the properties of cryopreserved cells. The viability of thawed cells was established with multiple in vitro assays, including analysis of liver gene expression, ureagenesis, cytochrome P450 activity, and growth factor-induced cell proliferation. The fate of transplanted cells was analysed in immunodeficient NOD-SCID mice. RESULTS: After thawing, the viability of human hepatocytes exceeded 60%. Cells attached to culture dishes, proliferated following growth factor stimulation and exhibited liver-specific functions. After transplantation in NOD-SCID mice, cells engrafted in the peritoneal cavity, a heterologous site, as well as the liver itself, retained hepatic function and proliferated in response to liver injury. Transplanted hepatocytes were integrated in the liver parenchyma. Occasionally, transplanted cells were integrated in bile ducts. CONCLUSIONS: Cryopreserved human liver cell showed the ability to retain functional integrity and to reconstitute both hepatic and biliary lineages in mice. These studies offer suitable paradigms aimed at characterizing liver cells prior to transplantation in people.

Animals↗
PubMed2003

Metal-catalyzed oxidation of extracellular matrix components perturbs hepatocyte survival with activation of intracellular signaling pathways.

To investigate whether oxidative manipulation of extracellular matrix components could affect cell survival, we studied primary rat hepatocytes cultured on dishes coated with collagen type 1, which was oxidized with a metal-based system. Culture of hepatocytes on oxidized collagen led to decreased cellular catalase activity along with impaired cell survival. The fraction of polyploid hepatocytes decreased early followed by greater reaccumulation of polyploid cells. Cells cultured on oxidized collagen showed greater susceptibility to additional oxidant stress induced by tert.-butyl-hydroperoxide. The capacity of hepatocytes for growth factor-induced DNA synthesis was unaffected by culture on oxidized collagen. In response to culture on oxidized matrix, AP-1, Egr-1, CREB, and NF-kappaB transcription factor activity was rapidly increased. This change in transcription factor activity was ameliorated by treatment of collagen with a free radical spin trap, N-tert.-butyl-alpha-phenylnitrone, prior to oxidation. Moreover, culture of hepatocytes with aminoguanidine, an antioxidant drug, decreased cell injury. These findings established that exposure of primary hepatocytes to oxidized extracellular matrix components rapidly activates cell signaling events with loss of hepatocyte subpopulations. Such cell-extracellular matrix interactions may play roles in organ homeostasis and oncogenetic progression.

Animals↗
PubMed2003

Loss of Omi mitochondrial protease activity causes the neuromuscular disorder of mnd2 mutant mice.

The mouse mutant mnd2 (motor neuron degeneration 2) exhibits muscle wasting, neurodegeneration, involution of the spleen and thymus, and death by 40 days of age. Degeneration of striatal neurons, with astrogliosis and microglia activation, begins at around 3 weeks of age, and other neurons are affected at later stages. Here we have identified the mnd2 mutation as the missense mutation Ser276Cys in the protease domain of the nuclear-encoded mitochondrial serine protease Omi (also known as HtrA2 or Prss25). Protease activity of Omi is greatly reduced in tissues of mnd2 mice but is restored in mice rescued by a bacterial artificial chromosome transgene containing the wild-type Omi gene. Deletion of the PDZ domain partially restores protease activity to the inactive recombinant Omi protein carrying the Ser276Cys mutation, suggesting that the mutation impairs substrate access or binding to the active site pocket. Loss of Omi protease activity increases the susceptibility of mitochondria to induction of the permeability transition, and increases the sensitivity of mouse embryonic fibroblasts to stress-induced cell death. The neurodegeneration and juvenile lethality in mnd2 mice result from this defect in mitochondrial Omi protease.

Amino Acid Sequence↗
PubMed2003

Inhibitor of apoptosis proteins are substrates for the mitochondrial serine protease Omi/HtrA2.

The mature serine protease Omi/HtrA2 is released from the mitochondria into the cytosol during apoptosis. Suppression of Omi/HtrA2 by RNA interference in human cell lines reduces cell death in response to TRAIL and etoposide. In contrast, ectopic expression of mature wildtype Omi/HtrA2, but not an active site mutant, induces potent caspase activation and apoptosis. In vitro assays demonstrated that Omi/HtrA2 could degrade inhibitor of apoptosis proteins (IAPs). Consistent with this observation, increased expression of Omi/HtrA2 in cells increases degradation of XIAP, while suppression of Omi/HtrA2 by RNA interference has an opposite effect. Combined, our data demonstrate that IAPs are substrates for Omi/HtrA2, and their degradation could be a mechanism by which the mitochondrially released Omi/HtrA2 activates caspases during apoptosis.

Apoptosis↗