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Biomedical subjects

R K Jain

Publications and source records attributed to R K Jain.

At least 109 records · Page 6Linked to original sources
PubMed1999

Water channel (aquaporin 1) expression and distribution in mammary carcinomas and glioblastomas.

The aquaporins represent a family of transmembrane water channel proteins that are widely distributed in various tissues throughout the body and play a major role in transcellular and transepithelial water movement. Most tumors have been shown to exhibit high vascular permeability and high interstitial fluid pressure, but the transport pathways for water within tumors remain unknown. In this study, we examined the distribution of the aquaporin 1 (AQP1) water channel protein in several types of transplanted tumor. Two mammary carcinomas, MCaIV and R3230AC, and three glioblastomas, HGL21, U87, and F98, were implanted in rats and mice. Two sites of implantation in rodents were chosen: a cranial window (CW) region and a subcutaneous (SC) region. Tissues were studied using immunoblot analysis and immunofluorescence staining. In the mammary carcinomas, AQP1 was localized in vascular structures; no differences between CW and SC regions were observed. Among the three glioblastomas, HGL21 and U87 exhibited similar AQP1 localization in vascular structures, whereas the center of F98 did not show vascular staining. Cell membranes of normal epithelial cells did not show AQP1 expression, while membranes of most tumor cells exhibited significant AQP1 expression. Interestingly, however, HGL21 and F98 in the CW locations showed no AQP1 expression on tumor cell membranes. These results show that the AQP1 water channel is heterogeneously expressed in tumor cells and their vasculature, and that the level of expression is determined not only by the specific cellular origin of the tumor, but also by the location of the tumor in the host animal.

Animals↗
PubMed1999

Degradation of phenanthrene by different bacteria: evidence for novel transformation sequences involving the formation of 1-naphthol.

Four polycyclic aromatic hydrocarbon (PAH)-degrading bacteria, namely Arthrobacter sulphureus RKJ4, Acidovorax delafieldii P4-1, Brevibacterium sp. HL4 and Pseudomonas sp. DLC-P11, capable of utilizing phenanthrene as the sole source of carbon and energy, were tested for its degradation using radiolabelled phenanthrene. [9-14C]Phenanthrene was incubated with microorganisms containing 100 mg/l unlabelled phenanthrene and the evolution of 14CO2 was monitored: within 18 h of incubation, 30.1, 35.6, 26.5 and 2.1% of the recovered radiolabelled carbon was degraded to 14CO2 by RKJ4, P4-1, HL4 and DLC-P11, respectively. When mixtures of other PAHs such as fluorene, fluoranthene and pyrene, in addition to phenanthrene, were added as additional carbon sources, there was a 36.1 and 20.6% increase in 14CO2 production from [9-14C]phenanthrene in the cases of RKJ4 and HL4, respectively, whereas P4-1 and DLC-P11 did not show any enhancement in 14CO2 production. Although, a combination of many bacteria enhances the degradation of organic compounds, no enhancement in the degradation of [9-14C]phenanthrene was observed in mixed culture involving all four microorganisms together. However, when different PAHs, as indicated above, were used in mixed culture, there was a 68.2% increase in 14CO2 production. In another experiment, the overall growth rate of P4-1 on phenanthrene could be enhanced by adding the non-ionic surfactant Triton X-100, whereas RKJ4, HL4 and DLC-P11 did not show any enhancement in growth. Pathways for phenanthrene degradation were also analysed by thin-layer chromatography, gas chromatography and gas chromatography-mass spectrometry. Common intermediates such as o-phthalic acid and protocatechuic acid were detected in the case of RKJ4 and o-phthalic acid was detected in the case of P4-1. A new intermediate, 1-naphthol, was detected in the cases of HL4 and DLC-P11. HL4 degrades phenanthrene via 1-hydroxy-2-naphthoic acid, 1-naphthol and salicylic acid, whereas DLC-P11 degrades phenanthrene via the formation of 1-hydroxy-2-naphthoic acid, 1-naphthol and o-phthalic acid. Both transformation sequences are novel and have not been previously reported in the literature. Mega plasmids were found to be present in RKJ4, HL4 and DLC-P11, but their involvement in phenanthrene degradation could not be established.

Bacteria↗
PubMed1999

Diffusion of macromolecules in agarose gels: comparison of linear and globular configurations.

The diffusion coefficients (D) of different types of macromolecules (proteins, dextrans, polymer beads, and DNA) were measured by fluorescence recovery after photobleaching (FRAP) both in solution and in 2% agarose gels to compare transport properties of these macromolecules. Diffusion measurements were conducted with concentrations low enough to avoid macromolecular interactions. For gel measurements, diffusion data were fitted according to different theories: polymer chains and spherical macromolecules were analyzed separately. As chain length increases, diffusion coefficients of DNA show a clear shift from a Rouse-like behavior (DG congruent with N0-0.5) to a reptational behavior (DG congruent with N0-2.0). The pore size, a, of a 2% agarose gel cast in a 0.1 M PBS solution was estimated. Diffusion coefficients of the proteins and the polymer beads were analyzed with the Ogston model and the effective medium model permitting the estimation of an agarose gel fiber radius and hydraulic permeability of the gels. Not only did flexible macromolecules exhibit greater mobility in the gel than did comparable-size rigid spherical particles, they also proved to be a more useful probe of available space between fibers.

Animals↗
PubMed1999

Mechanics of interstitial-lymphatic fluid transport: theoretical foundation and experimental validation.

Interstitial fluid movement is intrinsically linked to lymphatic drainage. However, their relationship is poorly understood, and associated pathologies are mostly untreatable. In this work we test the hypothesis that bulk tissue fluid movement can be evaluated in situ and described by a linear biphasic theory which integrates the regulatory function of the lymphatics with the mechanical stresses of the tissue. To accomplish this, we develop a novel experimental and theoretical model using the skin of the mouse tail. We then use the model to demonstrate how interstitial-lymphatic fluid movement depends on a balance between the elasticity, hydraulic conductivity, and lymphatic conductance as well as to demonstrate how chronic swelling (edema) alters the equipoise between tissue fluid balance parameters. Specifically, tissue fluid equilibrium is perturbed with a continuous interstitial infusion of saline into the tip of the tail. The resulting gradients in tissue stress are measured in terms of interstitial fluid pressure using a servo-null system. These measurements are then fit to the theory to provide in vivo estimates of the tissue hydraulic conductivity, elastic modulus, and overall resistance to lymphatic drainage. Additional experiments are performed on edematous tails to show that although chronic swelling causes an increase in the hydraulic conductivity, its greatly increased distensibility (due to matrix remodeling) dampens the driving forces for fluid movement and leads to fluid stagnation. This model is useful for examining potential treatments for edema and lymphatic disorders as well as substances which may alter tissue fluid balance and/or lymphatic drainage.

Animals↗
PubMed1999

Characterization of distinct Gal:3-O-sulfotransferase activities in human tumor epithelial cell lines and of calf lymph node GlcNAc : 6-O-sulfotransferase activity.

We found earlier in human breast and colon tumors, an augmented level of Gal : 3-O-sulfotransferase activities showing, respectively, an acceptor preference to blood group T-hapten (Group A enzymes) or Galbeta1,4GlcNAc (Group B enzymes) on the mucin Core 2 structure [Chandrasekaran EV, Jain RK, Vig R, and Matta KL (1997) Glycobiology 7: 753-68]. The present study reports these enzyme activities in human tumor cell lines and additional tumor specimens. The human colon tumor epithelial cell lines, akin to their parent tumors, express Group B enzyme activity. The acceptor specificity and kinetic properties, such as divalent metal ion activation and pH dependent activity profile, of the colon cancer line LS180 enzyme activity are identical to those of colon tissue specimens. Consistent with breast tumor specimens, the Group A enzyme activity is present in human breast tumor epithelial cell lines, with some exceptions. The Gal : 3-O-sulfotransferases show specific binding to Aleuria aurantia lectin, suggesting the presence of asparagine linked carbohydrate chains containing an inner core alpha1,6-fucosyl residue on these enzymes. Calf lymph nodes contain GlcNAc : 6-O-sulfotransferase as well as Group A Gal : 3-O-sulfotransferase activities, which differ in pH dependent profiles, pH optima (7.6 and 7.0, respectively) and the influence of Mn2+.

Animals↗
PubMed1999

Neurotoxic potential of three structural analogs of beta-N-oxalyl-alpha,beta-diaminopropanoic acid (beta-ODAP).

Lathyrism is a non-progressive motor neuron disease produced by consumption of the excitatory amino acid, 3-N-oxalyl-L-2,3-diaminopropanoic acid (beta-ODAP). To learn more about the mechanisms underlying Lathyrism three structural analogs of beta-ODAP were synthesized. Carboxymethyl-alpha,beta-diaminopropanoic acid (CMDAP) evoked inward currents which were antagonized by APV (30 microM), but not by CNQX (10 microM). N-acetyl-alpha,beta-diaminopropanoic acid (ADAP) evoked no detectable ionic currents but potentiated N-methyl-D-aspartate (NMDA)-activated currents. The potentiation of NMDA currents by ADAP was blocked by 7-chlorokynurenic acid. Carboxymethylcysteine (CMC) did not activate any detectable ionic currents. None of the three beta-ODAP analogs produced visible symptoms of toxicity in day old chicks when administered for 2-3 consecutive days. Ligand binding studies demonstrated that all the three compounds were effective to in displacing [3H]glutamate. The maximum inhibition was 92% for CMDAP, 61% for ADAP, 65% for CMC and 99% for beta-ODAP. These data indicate that analogs of beta-ODAP may interact with glutamate receptors without producing neurotoxicity.

Amino Acids, Diamino↗
PubMed1999

Tumor-host interactions in the gallbladder suppress distal angiogenesis and tumor growth: involvement of transforming growth factor beta1.

Angiogenesis inhibitors produced by a primary tumor can create a systemic anti-angiogenic environment and maintain metastatic tumor cells in a state of dormancy. We show here that the gallbladder microenvironment modulates the production of transforming growth factor (TGF)-beta1, a multifunctional cytokine that functions as an endogenous anti-angiogenic and anti-tumor factor in a cranial window preparation. We found that a wide variety of human gallbladder tumors express TGF-beta1 irrespective of histologic type. We implanted a gel impregnated with basic fibroblast growth factor or Mz-ChA-2 tumor in the cranial windows of mice without tumors or mice with subcutaneous or gallbladder tumors to study angiogenesis and tumor growth at a secondary site. Angiogenesis, leukocyte-endothelial interaction in vessels and tumor growth in the cranial window were substantially inhibited in mice with gallbladder tumors. The concentration of TGF-beta1 in the plasma of mice with gallbladder tumors was 300% higher than that in the plasma of mice without tumors or with subcutaneous tumors. In contrast, there was no difference in the plasma levels of other anti- and pro-angiogenic factors. Treatment with neutralizing antibody against TGF-beta1 reversed both angiogenesis suppression and inhibition of leukocyte rolling induced by gallbladder tumors. TGF-beta1 also inhibited Mz-ChA-2 tumor cell proliferation. Our results indicate that the production of anti-angiogenesis/proliferation factors is regulated by tumor-host interactions.

Angiostatins↗
PubMed1999

Creatine and cyclocreatine treatment of human colon adenocarcinoma xenografts: 31P and 1H magnetic resonance spectroscopic studies.

Creatine (Cr) and cyclocreatine (cyCr) have been shown to inhibit the growth of a variety of human and murine tumours. The purpose of this study was to evaluate the anti-tumour effect of these molecules in relation to drug accumulation, energy metabolism, tumour water accumulation and toxicity. Nude mice carrying a human colon adenocarcinoma (LS174T) with a creatine kinase (CK) activity of 2.12 units mg(-1) protein were fed Cr (2.5% or 5%) or cyCr (0.025%, 0.1% or 0.5%) for 2 weeks and compared with controls fed standard diet. Cr concentrations of 2.5% and 5% significantly inhibited tumour growth, as did 0.1% and 0.5% cyCr. In vivo 31P magnetic resonance spectroscopy (MRS) after 2 weeks of treatment showed an increase in [phosphocreatine (PCr)+phosphocyclocreatine (PcyCr)]/nucleoside triphosphate (NTP) with increasing concentrations of dietary Cr and cyCr, without changes in absolute NTP contents. The antiproliferative effect of the substrates of CK was not related to energy deficiency but was associated with acidosis. Intratumoral substrate concentrations (measured by 1H-MRS) of 4.8 micromol g(-1) wet weight Cr (mice fed 2.5% Cr) and 6.2 micromol g(-1) cyCr (mice fed 0.1% cyCr) induced a similar decrease in growth rate, indicating that both substrates were equally potent in tumour growth inhibition. The best correlant of growth inhibition was the total Cr or (cyCr+Cr) concentrations in the tissue. In vivo, these agents did not induce excessive water accumulation and had no systemic effects on the mice (weight loss, hypoglycaemia) that may have caused growth inhibition.

Adenocarcinoma↗
PubMed1999

Cells shed from tumours show reduced clonogenicity, resistance to apoptosis, and in vivo tumorigenicity.

The goal of this study was to compare growth characteristics of cells shed from a tumour with the native tumour cells. The human colon adenocarcinoma LS174T and its highly metastatic subline LS LiM 6 were grown as tissue-isolated tumours in nude mice and perfused to collect shed cells. The tumours were then excised and prepared into single-cell suspensions. Clonogenicity in 0.3-0.9% agarose, apoptotic fraction, and in vivo tumorigenicity were determined for each population. In both tumour lines, shed cells were less clonogenic, more apoptotic and less tumorigenic than cells isolated directly from their native tissue. These findings suggest that shed cells have a low metastatic potential compared to native tumour cells, most likely because they represent an apoptotic population.

Adenocarcinoma↗
PubMed1999

Changes in vascularization of human breast cancer xenografts responding to antiestrogen therapy.

To elucidate the previously suggested vascular effect(s) of antiestrogen therapy, we studied the effect of estrogen withdrawal and tamoxifen on 1) vascular resistance, 2) glucose and oxygen consumption, and 3) vascular density in a perfused breast cancer line (ZR75-1). Furthermore, we examined ZR75-1 tumors by functional CT-scanning (fCT) to determine changes in parameters related to tumor capillary transfer constants and vascular volume fraction in response to antiestrogenic manipulations. The vascular resistance decreased significantly from 42.7 to 20.8 mmHg x min x g x ml(-1) (P< .03) on day 9 after estrogen withdrawal, but not after 9 days of tamoxifen treatment. The estrogen-depleted tumors were significantly smaller than controls on day 9. There was no difference in nutrient consumption or vascular density in any of the experimental groups compared to controls. fCT showed an increase (P < .03) in vascular volume fraction during tumor growth, and this parameter was significantly lower after estrogen withdrawal when compared to controls (P < .05). Vascular resistance correlated with tumor size (R = 0.7, P < .0001), indicating that vascular resistance increases during tumor growth. The changes in vascular parameters after estrogen withdrawal indicate a vascular remodeling effect. This inhibition of vascular development by hormone deprivation may have important implications for future planning of multimodal treatment regimens.

Animals↗
PubMed1999

Return of lymphatic function after flap transfer for acute lymphedema.

OBJECTIVE: The goals of this work were to develop animal models of lymphedema and tissue flap transfer, and to observe physiologic changes in lymphatic function that occur in these models over time, both systemically with lymphoscintigraphy (LS) and locally using fluorescence microlymphangiography (FM). SUMMARY BACKGROUND DATA: Although lymphedema has been managed by a combination of medical and surgical approaches, no effective long-term cure exists. Surgical attempts aimed at reconnecting impaired lymphatic channels or bypassing obstructed areas have failed. METHODS: The tails of rats (A groups) and mice (B groups) were used because of their different features. Lymphedema was created by ligation of the lymphatics at the tail base and quantified by diameter measurements there. In the experimental group, rectus abdominis myocutaneous flap was transferred across the ligation. In addition to the ligation (A1 and B1) and ligation + flap (A2 and B2) groups, three control groups were included: sham flap with ligation (B4), sham flap alone (B5), and normal (A3 and B3) animals. Observations were made at weekly time points for lymphatic function and continuity. RESULTS: Lymphedema was successfully created in the mouse ligation groups (B1 and B4) and sustained for the entire length of observation (up to 14 weeks). Lymphatic continuity was restored in those animals with transferred flaps across the ligation site (A2 and B2), as seen both by LS and FM. Sham flaps did not visibly affect lymphatic function nor did they cause any visible swelling in the tail. CONCLUSIONS: Acute lymphedema developing after ligation of tail lymphatics in mice can be prevented by myocutaneous flap transfer. Restored lymphatic continuity and function were demonstrable using lymphoscintigraphy and fluorescence microlymphangiography.

Acute Disease↗
PubMed1999

Transport of molecules, particles, and cells in solid tumors.

Extraordinary advances in molecular biology and biotechnology have led to the development of a vast number of therapeutic anti-cancer agents. To reach cancer cells in a tumor, a blood-borne therapeutic molecule, particle, or cell must make its way into the blood vessels of the tumor and across the vessel wall into the interstitium, which it then must migrate through. Unfortunately, tumors often develop in ways that hinder these steps. The goal of research in this area is to analyze each of these steps experimentally and theoretically and integrate the resulting information into a unified theoretical framework. This paradigm of analysis and synthesis has fostered a better understanding of physiological barriers in solid tumors and aided in the development of novel strategies to exploit and/or overcome these barriers for improved cancer detection and treatment.

Animals↗
PubMed1998

Primary tumor size-dependent inhibition of angiogenesis at a secondary site: an intravital microscopic study in mice.

Some primary tumors are capable of suppressing the growth of their metastases by presumably generating antiangiogenic factors such as angiostatin. We hypothesized that the amount of inhibitor(s) released by a tumor increases with tumor growth. We tested this hypothesis by evaluating the relationship between the size of a primary tumor and its ability to inhibit angiogenesis at a secondary site. Furthermore, we characterized the effects of the primary tumor on physiological properties of newly formed vessels at the secondary site. Angiogenesis and physiological properties were measured using intravital microscopy of angiogenic vessels in the gels containing basic fibroblast growth factor placed into cranial windows of immunodeficient mice bearing human prostatic carcinoma (PC-3) in their flank. The PC-3 tumor inhibited angiogenesis in the gels, and surgical resection of tumor reversed this inhibition. The inhibition of angiogenesis 20 days after gel implantation (range, 0-83%) correlated positively (r = 0.625; P < 0.008) with the tumor size on the day of gel implantation (range, 19-980 mm3). The primary tumor also suppressed leukocyte-adhesion in angiogenic vessels, thus helping them evade the immune recognition. These results provide an additional rationale for combining antiangiogenic treatment with local therapies.

Animals↗
PubMed1998

Tumor induction of VEGF promoter activity in stromal cells.

We have established a line of transgenic mice expressing the A. victoria green fluorescent protein (GFP) under the control of the promoter for vascular endothelial growth factor (VEGF). Mice bearing the transgene show green cellular fluorescence around the healing margins and throughout the granulation tissue of superficial ulcerative wounds. Implantation of solid tumors in the transgenic mice leads to an accumulation of green fluorescence resulting from tumor induction of host VEGF promoter activity. With time, the fluorescent cells invade the tumor and can be seen throughout the tumor mass. Spontaneous mammary tumors induced by oncogene expression in the VEGF-GFP mouse show strong stromal, but not tumor, expression of GFP. In both wound and tumor models the predominant GFP-positive cells are fibroblasts. The finding that the VEGF promoter of nontransformed cells is strongly activated by the tumor microenvironment points to a need to analyze and understand stromal cell collaboration in tumor angiogenesis.

Animals↗
PubMed1998

Endothelial cell death, angiogenesis, and microvascular function after castration in an androgen-dependent tumor: role of vascular endothelial growth factor.

The sequence of events that leads to tumor vessel regression and the functional characteristics of these vessels during hormone-ablation therapy are not known. This is because of the lack of an appropriate animal model and monitoring technology. By using in vivo microscopy and in situ molecular analysis of the androgen-dependent Shionogi carcinoma grown in severe combined immunodeficient mice, we show that castration of these mice leads to tumor regression and a concomitant decrease in vascular endothelial growth factor (VEGF) expression. Androgen withdrawal is known to induce apoptosis in Shionogi tumor cells. Surprisingly, tumor endothelial cells begin to undergo apoptosis before neoplastic cells, and rarefaction of tumor vessels precedes the decrease in tumor size. The regressing vessels begin to exhibit normal phenotype, i.e., lower diameter, tortuosity, vascular permeability, and leukocyte adhesion. Two weeks after castration, a second wave of angiogenesis and tumor growth begins with a concomitant increase in VEGF expression. Because human tumors often relapse following hormone-ablation therapy, our data suggest that these patients may benefit from combined anti-VEGF therapy.

Androgens↗
PubMed1998

Role of HIF-1alpha in hypoxia-mediated apoptosis, cell proliferation and tumour angiogenesis.

As a result of deprivation of oxygen (hypoxia) and nutrients, the growth and viability of cells is reduced. Hypoxia-inducible factor (HIF)-1alpha helps to restore oxygen homeostasis by inducing glycolysis, erythropoiesis and angiogenesis. Here we show that hypoxia and hypoglycaemia reduce proliferation and increase apoptosis in wild-type (HIF-1alpha+/+) embryonic stem (ES) cells, but not in ES cells with inactivated HIF-1alpha genes (HIF-1alpha-/-); however, a deficiency of HIF-1alpha does not affect apoptosis induced by cytokines. We find that hypoxia/hypoglycaemia-regulated genes involved in controlling the cell cycle are either HIF-1alpha-dependent (those encoding the proteins p53, p21, Bcl-2) or HIF-1alpha-independent (p27, GADD153), suggesting that there are at least two different adaptive responses to being deprived of oxygen and nutrients. Loss of HIF-1alpha reduces hypoxia-induced expression of vascular endothelial growth factor, prevents formation of large vessels in ES-derived tumours, and impairs vascular function, resulting in hypoxic microenvironments within the tumour mass. However, growth of HIF-1alpha tumours was not retarded but was accelerated, owing to decreased hypoxia-induced apoptosis and increased stress-induced proliferation. As hypoxic stress contributes to many (patho)biological disorders, this new role for HIF-1alpha in hypoxic control of cell growth and death may be of general pathophysiological importance.

Animals↗
PubMed1998

Increased rates of CD4(+) and CD8(+) T lymphocyte turnover in simian immunodeficiency virus-infected macaques.

Defining the rate at which T cells turn over has important implications for our understanding of T lymphocyte homeostasis and AIDS pathogenesis, yet little information on T cell turnover is available. We used the nucleoside analogue bromodeoxyuridine (BrdUrd) in combination with five-color flow cytometric analysis to evaluate T lymphocyte turnover rates in normal and simian immunodeficiency virus (SIV)-infected rhesus macaques. T cells in normal animals turned over at relatively rapid rates, with memory cells turning over more quickly than naive cells. In SIV-infected animals, the labeling and elimination rates of both CD4(+) and CD8(+) BrdUrd-labeled cells were increased by 2- to 3-fold as compared with normal controls. In normal and SIV-infected animals, the rates of CD4(+) T cell BrdUrd-labeling and decay were closely correlated with those of CD8(+) T cells. The elimination rate of BrdUrd-labeled cells was accelerated in both naive and memory T lymphocytes in SIV-infected animals. Our results provide direct evidence for increased rates of both CD4(+) and CD8(+) T cell turnover in AIDS virus infection and have important implications for our understanding of T cell homeostasis and the mechanisms responsible for CD4(+) T cell depletion in AIDS.

Animals↗