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Biomedical subjects

R Agarwal

Publications and source records attributed to R Agarwal.

At least 19 recordsLinked to original sources
PubMed1995

Long-term culture of chronic myelogenous leukemia marrow cells on stem cell factor-deficient stroma favors benign progenitors.

Long-term culture of marrow from patients with chronic myelogenous leukemia (CML) has been reported to favor the outgrowth of bcr/abl- progenitor cells in some patients. We examined the effect of the presence of soluble or transmembrane forms of stem cell factor (SCF) in long-term cultures of CML marrow. CD34-enriched cells from CML patients in advanced chronic phase or accelerated phase were plated on immortalized fetal liver stromal cells from homozygous SCF-deficient SI/SI mice (SI/SI4) with or without the addition of soluble human SCF, SI/SI4 cells expressing high levels of the transmembrane form of human SCF (SI/SIh220), or primary human allogeneic stroma. Cells were removed from cultures and plated weekly in colony assays. The clonagenic cell output from cultures completely lacking SCF was lower over the first 2 to 3 weeks, but by 5 weeks was similar to the clonagenic cell output from the other culture conditions. Analysis of bcr/abl transcripts from individual colonies showed a lower percentage of malignant progenitors present in long-term cultures completely deficient in SCF than under the other culture conditions, particularly compared with primary human stroma-containing long-term cultures. SCF may specifically favor malignant versus benign progenitor cells present in the marrow of CML patients, and an abnormal proliferative response to SCF in very primitive cells may be an underlying defect in the pathophysiology of this disease.

Adult↗
PubMed1995

Antibody reactivity to the HRES-1 endogenous retroviral element identifies a subset of patients with systemic lupus erythematosus and overlap syndromes. Correlation with antinuclear antibodies and HLA class II alleles.

OBJECTIVE: To evaluate the correlation between the presence of antibodies to an endogenous retroviral element-encoded nuclear protein autoantigen, HRES-1, and the presence of other antinuclear antibodies and HLA class II alleles in patients with systemic lupus erythematosus (SLE) and overlap syndromes. METHODS: Antibody reactivities to native and recombinant proteins and synthetic peptides were assessed by counterimmunoelectrophoresis, enzyme-linked immunosorbent assay, and Western blotting. HLA class II alleles were determined by oligonucleotide typing. RESULTS: Forty-eight percent of the 153 patients with autoimmune disease, and 52% of the subgroup with SLE, had HRES-1 antibodies. In contrast, 3.6% of 111 normal donors, and none of 42 patients with the acquired immunodeficiency syndrome or 50 asymptomatic human immunodeficiency virus 1-infected patients, had HRES-1 antibodies. Chi-square analyses revealed a significant association between anti-HRES-1 and anti-RNP and an inverse correlation between HRES-1 and Ro/La autoantibodies in patients with SLE or overlap syndromes. Antigenic epitopes of HRES-1 and the retroviral gag-related region of the 70-kd protein component of U1 small nuclear RNP, which share 3 consecutive highly charged amino acids (Arg-Arg-Glu), an additional Arg, and functionally similar Arg/Lys residues, represent cross-reactive epitopes between the two proteins. Selective removal of HRES-1 antibodies from sera of HRES-1-seropositive/RNP-seropositive patients by absorption on recombinant HRES-1/glutathione-S-transferase-conjugated agarose beads had no effect on anti-RNP reactivities. A comparative multivariate analysis of HLA class II genes revealed a differential segregation of DQB1 alleles in HRES-1-seropositive versus HRES-1-seronegative patients (P = 0.04). While a relative increase of DQB1*0402 among HRES-1-seropositive patients was noted across ethnic groups (P = 0.02), a decrease of DQB1*0201 and DQB1*0301 was found in white HRES-1-seropositive patients (P = 0.04). CONCLUSION: Autoantibodies to HRES-1 are detectable in a distinct subset of patients with autoimmune disease, primarily in those who do not have antibodies to Ro and La. Anti-HRES-1 and anti-RNP reactivities are mediated by cross-reactive but separate antibody molecules. HLA-DQB genes, rather than HLA-DRB or DQA genes, may have a more significant influence on generation of these antinuclear autoantibodies.

Alleles↗
PubMed1995

In-hospital outcome of percutaneous transluminal coronary angioplasty for long lesions and diffuse coronary artery disease.

We performed coronary angioplasty on 151 long or diffuse lesions (120 long and 31 diffuse) in 141 patients (86% male, mean age 50 +/- 9 years). Long lesions were defined as lesions 11-20 mm in length and diffuse lesions as lesions longer than 20 mm, or three or more lesions in the same vessel. One or more adverse morphologic features were present in 131 (93%) lesions. Long balloons were used in 44%, significantly more often for diffuse disease (long lesions 39% and diffuse disease 64%; P = 0.004). Newer devices including the rotational atherectomy device (9 lesions), stents and perfusion balloons were employed in 18 (12%) lesions, more often for diffuse lesions (long lesions 8% vs. diffuse lesions 26%; P = 0.017). Lesion severity was comparable in the two groups (long lesions: 88 +/- 7%; diffuse lesions: 88 +/- 8%), but diffuse lesions were associated with significantly higher residual stenosis (long lesions: 6 +/- 8%; diffuse lesions: 12 +/- 13%, P = 0.01). Major complications occurred in five (3.5%) patients, including one death (0.7% mortality). The angiographic and clinical success rates for all patients were 99% and 96%, respectively, and were comparable for long and diffuse lesions. Judicious case selection and the use of long balloons and newer interventional devices permit coronary angioplasty for long lesions and diffuse disease with excellent success and a low risk of complications. Diffuse lesions are associated with more frequent use of long balloons and newer devices, especially rotational atherectomy and slightly higher residual stenosis as compared to long lesions.

Adult↗
PubMed1995

Inhibition of ras p21 membrane localization and modulation of protein kinase C isozyme expression during regression of chemical carcinogen-induced murine skin tumors by lovastatin.

We investigated the ras p21 membrane localization and the expression and activation of protein kinase C (PKC) isozymes in activated ras oncogene-containing tumors and assessed whether these events were related to tumor growth. We used 7,12-dimethylbenz[a]anthracene-initiated and 12-O-tetradecanoylphorbol-13-acetate-promoted SENCAR mouse skin tumors, which were shown to contain Ha-ras oncogene activated by point mutation at codon 61, as an in vivo model for these studies. Compared with levels in epidermis, highly elevated levels of membrane-bound Ha-ras p21 were observed in growing tumors, which also showed strong expression and membrane translocation of PKC zeta and beta II and weak expression of PCK alpha. However, when ras p21 membrane localization was blocked in vivo in growing tumors by lovastatin, opposite results were evident. Compared with saline-treated animals, in which tumor growth continued, lovastatin-treated animals had significantly inhibited tumor growth, which led to tumor regression with concomitant inhibition of Ha-ras p21 membrane localization. These regressing tumors from lovastatin-treated animals also showed a decrease in the expression and membrane translocation of PKC zeta and beta II but increased expression of PKC alpha. Taken together, our results indicate that ras p21 membrane localization and the expression and activation of PKC zeta, beta II, and alpha may be the critical events in the regulation of the growth of tumors that contain activated ras oncogenes.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1995

A rapid and convenient filter-binding assay for ras p21 processing enzyme farnesyltransferase.

Because it is the target for the development of anti-cancer agents, the mammalian cytosolic enzyme farnesyltransferase (FTase) has received significant attention in recent years. FTase catalyzes the transfer of a farnesyl group from farnesylpyrophosphate (FPP) to cysteine 185/186 at the carboxyl terminal end of ras proteins (ras p21), a reaction essential for the localization of ras p21 to the plasma membrane for their cellular functions including cell transformation in case of oncogenic ras p21. Here, we report the development of a rapid and convenient assay procedure for FTase using phosphocellulose paper which has a binding affinity for proteins. The FTase is assayed as the transfer of [3H]farnesyl group from [3H]FPP to the ras p21 at pH 7.4 and 37 degrees C in the presence of rat brain cytosol followed by the binding of radioactive farnesylated ras p21 to the phosphocellulose paper. The radioactivity associated with ras p21 bound to the phosphocellulose paper was determined by scintillation counting after soaking the paper in trichloroacetic acid and washing with distilled water. Utilizing [3H]FPP and recombinant Ha-ras p21 as substrates in the reaction, the FTase followed Michaelis-Menten kinetics with Km values of 1.0 and 7.69 microM for respectively [3H]FPP and recombinant Ha-ras p21. The method reported here has the advantages over the other published assay procedures of being rapid, convenient and economical, and can be successfully used for the basic assaying of FTase in different organs and distinct species and for the screening of novel inhibitors of FTase.

Alkyl and Aryl Transferases↗
PubMed1995

Inhibition of 12-O-tetradecanoylphorbol-13-acetate and other skin tumor-promoter-caused induction of epidermal interleukin-1 alpha mRNA and protein expression in SENCAR mice by green tea polyphenols.

Recent studies have shown that topical application of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) to murine skin results in increased expression of the highly inflammatory cytokine interleukin (IL)-1 alpha in the epidermis. This has led to the suggestion that IL-1 alpha directly or indirectly mediates the inflammatory and hyperplastic responses elicited by TPA and possibly by other skin tumor promoters. In the current study, we investigated the effect of skin application of a polyphenolic fraction isolated from green tea (GTP) to SENCAR mice on skin tumor-promoter-caused induction of cutaneous edema and hyperplasia, and IL-1 alpha mRNA expression. Pretreatment of the skin with GTP 30 min before that of anthralin, benzoyl peroxide, mezerein, and TPA resulted in a significant (p < 0.05) inhibition of cutaneous edema and epidermal hyperplasia caused by each of these tumor promoters. Northern blot analysis indicated that topical application of TPA, anthralin, mezerein, or benzoyl peroxide to SENCAR mice resulted in an increased expression of epidermal IL-1 alpha mRNA. Pretreatment of the skin with GTP or individual epicatechin derivatives (ECDs) present therein, 30 min before that of TPA, resulted in a significant inhibition of enhanced expression of epidermal IL-1 alpha mRNA caused by skin application of TPA. These inhibitory effects were found to be dependent on the dose of GTP. Among four epicatechin derivatives present in GTP, (-)-epicatechin-3-gallate and (-)-epigallocatechin-3-gallate were more effective than (-)-epigallocatechin and (-)-epicatechin in affording this inhibition. Preapplication of GTP was also found to afford inhibition against anthralin-, benzoyl peroxide-, and mezerein-caused increased expression of epidermal IL-1 alpha mRNA and protein. Our study suggests that the inhibition of tumor-promoter-induced IL-1 alpha mRNA and protein expression in mouse epidermis by green tea in combination with other inhibitory effects may be responsible for the anti-tumor-promoting and anti-inflammatory effects of GTP.

Animals↗
PubMed1994

Evidence for multiple inducible cytochrome P450 isozymes in SENCAR mouse skin by pyridine.

Pyridine, an amphipathic solvent, is widely used in industry and is also a constituent of tobacco and its smoke. Since, in addition to inhalation and ingestion, pyridine is also readily absorbed through skin, we assessed the effect of skin application of pyridine on monooxygenase activities and cytochrome P450 (CYP) isozymes and CYP mRNA levels in the skin of SENCAR mice. Compared to controls, a single topical application of pyridine (30 or 50 mg/100 g body weight) resulted in induction of cutaneous 7-ethoxyresorufin O-deethylase, 7-pentoxyresorufin O-depentylase, and erythromycin N-demethylase activities. Pyridine treatment also resulted in an increase in reactivity with monoclonal antibodies directed against CYP 1A1, 2B1 and 3A. In Northern blot analysis, treatment of pyridine also showed a significant increase in mRNA for Cyp1a-1 in the skin. These data indicate that murine skin contains multiple inducible CYP isozymes, and that pyridine results in the induction of at least three families of CYP in murine skin.

Animals↗
PubMed1994

Pathophysiology of potassium absorption and secretion by the human intestine.

When normal people ingest 90 mEq/day of K+ in their diet, they absorb about 90% of intake (81 mEq) and excrete an equivalent amount of K+ in the urine. Normal fecal K+ excretion averages about 9 mEq/day. The vast majority of intestinal K+ absorption occurs in the small intestine; the contribution of the normal colon to net K+ absorption and secretion is trivial. K+ is absorbed or secreted mainly by passive mechanisms; the rectum and perhaps the sigmoid colon have the capacity to actively secrete K+, but the quantitative and physiological significance of this active secretion is uncertain. Hyperaldosteronism increases fecal K+ excretion by about 3 mEq/day in people with otherwise normal intestinal tracts. Cation exchange resin by mouth can increase fecal K+ excretion to 40 mEq/day. The absorptive mechanisms of K+ are not disturbed by diarrhea per se, but fecal K+ losses are increased in diarrheal diseases by unabsorbed anions (which obligate K+), by electrochemical gradients secondary to active chloride secretion, and probably by secondary hyperaldosteronism. In diarrhea, total body K+ can be reduced by two mechanisms: loss of muscle mass because of malnutrition and reduced net absorption of K+; only the latter causes hypokalemia. Balance studies in patients with diarrhea are exceedingly rare, but available data emphasize an important role for dietary K+ intake, renal K+ excretion, and fecal K+ losses in determining whether or not a patient develops hypokalemia. The paradoxical negative K+ balance induced by ureterosigmoid anastomosis is described. The concept that fecal K+ excretion is markedly elevated in patients with uremia as an intestinal adaptation to prevent hyperkalemia is analyzed; we conclude that the data do not convincingly show the existence of a major intestinal adaptive response to chronic renal failure.

Adaptation, Physiological↗
PubMed1994

Chemical and enzyme-catalysed synthesis of quinoline arene hydrates.

Arene hydrates of quinoline have been synthesized by enzyme-catalysed benzylic and allylic hydroxylation of dihydroquinolines in growing cultures of the fungus Mortierella isabellina and in liver microsomal preparations. A preference for allylic hydroxylation was generally observed in eukaryotic systems. Evidence of epoxidation of dihydroarenes by both the fungal and animal enzyme systems was also obtained. The chemical synthesis of these arene hydrates (5-hydroxy-5,6-dihydroquinoline, 6-hydroxy-5,6-dihydroquinoline, 7-hydroxy-7,8-dihydroxyquinoline, and 8-hydroxy-7,8-dihydroquinoline) from the corresponding hydroxy-5,6,7,8-tetrahydroquinolines, has also been accomplished.

Animals↗
PubMed1994

The post-transurethral resection of prostate syndrome: therapeutic proposals.

Absorption of large volumes of irrigation fluid during transurethral resection of the prostate (TURP) can produce hyponatremia, coma, blindness, and cardiorespiratory depression. This has been termed the "post-TURP syndrome." The pathophysiology and management of this syndrome are controversial. A case of severe post-TURP syndrome due to the absorption of hypotonic glycine irrigant is reported. This patient developed severe hyponatremia, slight hypo-osmolality, hyperglycinemia, hyperserinemia, hyperammonemia, and hypocalcemia. He became comatose, profoundly hypotensive, bradycardic, and transiently blind. Because of this combination of severe biochemical, neurologic, and hemodynamic abnormalities, we elected to treat this patient with hemodialysis. The biochemical and clinical manifestations resolved completely. The pathophysiology and treatment of this disorder are discussed and a role for hemodialysis is suggested.

Aged↗
PubMed1994

Inhibitory effect of silymarin, an anti-hepatotoxic flavonoid, on 12-O-tetradecanoylphorbol-13-acetate-induced epidermal ornithine decarboxylase activity and mRNA in SENCAR mice.

In recent years, considerable emphasis has been placed on identifying new cancer chemopreventive agents which could be useful for human populations. Silymarin, an anti-oxidant flavonoid isolated from artichoke, has been shown to possess significant activity against hepatotoxicity and other pharmacological and physiological disorders. Since many antioxidants inhibit tumor promotion, and because ornithine decarboxylase (ODC) is a well known biochemical marker of tumor promotion, we assessed the effect of skin application of silymarin on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced epidermal ODC activity and ODC mRNA levels in SENCAR mice. Application of silymarin at doses of 0.5-18 mg (1-37 mumol)/mouse prior to that of TPA (2.5 micrograms) treatment resulted in significant inhibition of TPA-induced epidermal ODC activity in a dose- and time-dependent manner. Northern blot analysis revealed that topical application of silymarin at the dose of 2 mg/mouse resulted in almost complete inhibition of TPA-induced epidermal ODC mRNA. In other studies, silymarin also showed significant inhibition of epidermal ODC activity induced by several other tumor promoters, including free radical-generating compounds. Our data suggest that silymarin could be a useful anti-tumor promoting agent capable of ameliorating the tumor promoting effects of a wide range of tumor promoters.

Animals↗
PubMed1994

Multiple cytochrome P450 isozymes in murine skin: induction of P450 1A, 2B, 2E, and 3A by dexamethasone.

Cytochrome P450s (P450s) are a supergene family of enzymes responsible for the metabolism of a wide range of endogenous and foreign compounds. P450 isozymes possess overlapping substrate specificity. Systemic administration of dexamethasone, a widely used topical agent in dermatologic practice, to animals is known to result in the induction of multiple P450 isozymes in liver. In this study the effect of topical application of dexamethasone to mice on P450-dependent monooxygenase activities, expression of P450 isozymes, and P450 mRNA levels in skin was assessed. The treatment of mice with dexamethasone resulted in significant induction of 7-ethoxyresorufin O-deethylase (2.3 times), 7-pentoxyresorufin O-depentylase (19.2 times), para-nitrophenol hydroxylase (7.5 times), and erythromycin N-demethylase (2.2 times) activities; the monooxygenases catalyzed preferentially by P450 isozymes 1A1, 2B1, 2E1, and 3A, respectively. Immunoblot analysis of cutaneous microsomes, employing antibodies directed against purified P450s 1A1/2, 2B1/2, 2E1, and 3A, showed that dexamethasone treatment results in an increased immunoreactivity (1.8-13.9 times). In immunohistochemical staining of skin with antibody against P4502B1/2, topical application of dexamethasone resulted in an increased reactivity towards microsomal protein in the suprabasal layer of the epidermis and with the cells of the hair follicles. Whereas constitutive expression of mRNAs for CYP1A1 and CYP2E1 was evident in murine skin, any change in the levels of these mRNAs following treatment with dexamethasone was not apparent. The results of our study indicate that the application of dexamethasone to murine skin results in the induction of several families of P450 isozymes, suggesting that murine skin contains multiple inducible P450 isozymes capable of participating in the metabolism of a wide range of xenobiotics and endogenous compounds.

Administration, Topical↗