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R K Jain

Publications and source records attributed to R K Jain.

At least 163 records · Page 9Linked to original sources
PubMed1997

Geometric resistance and microvascular network architecture of human colorectal carcinoma.

OBJECTIVE: To measure the geometric resistance to blood flow in human colorectal carcinoma. Although tumor blood flow is of central importance in both the detection and the treatment of cancer, the determinants of blood flow through the neoplastic circulation are poorly understood. METHODS: Human colorectal carcinomas (tissue weight = 272 g +/- 43 g (SD), n = 6) were perfused ex vivo with a buffered physiological salt solution of known viscosity at flow rates ranging from 2.5 to 40 ml/min and perfusion pressures from 8 to 100 mm Hg. The geometric resistance was determined from the slope of the pressure-flow curve. For examination of the principal determinant of geometric resistance, the vascular architecture, one of the tumors was perfused with Batson's No. 17 polymer and macerated in KOH to produce a positive vascular east that was used for measurement of vascular branching patterns and dimensions. RESULTS: The pressure-flow relationship was linear at perfusion pressures above 40 mm Hg, and the geometric resistance, zzero, was constant at approximately 6.5 x 10(9) g/cm3. Below 40 mm Hg, zzero increased rapidly. The architecture of the arteriolar and capillary networks of human colorectal carcinoma is similar to those of experimental rodent tumors. Capillaries in planar and nonplanar meshworks had mean segment diameters of 11 +/- 2 and 9.6 +/- 2 microns, lengths of 46 +/- 24 and 107 +/- 40 microns, and intercapillary distances of 46 +/- 13 and 74 +/- 24 microns, respectively. CONCLUSIONS: The geometric flow resistance in neoplastic tissue is 1-2 orders of magnitude higher than that observed in normal tissues. A decrease in functional vascular cross-sectional area may explain the additional increase in resistance at small perfusion pressures. The observed flow resistance may be due to the specialized arteriolar and capillary network architecture, pressure exerted by proliferating cancer cells, and/or coupling between vascular and extravascular flow. These observations demonstrate that tumor vascularity alone may not be indicative of flow resistance or tumor susceptibility to blood-borne therapeutic agents.

Adenocarcinoma↗
PubMed1997

Effect of tumor necrosis factor alpha on vascular resistance, nitric oxide production, and glucose and oxygen consumption in perfused tissue-isolated human melanoma xenografts.

The effect of tumor necrosis factor alpha (TNF-alpha) on vascular resistance, nitric oxide production, and consumption of oxygen and glucose was examined in a perfused tissue-isolated tumor model in nude mice. One experimental group was perfused with heparinized Krebs-Henseleit buffer, a second one was perfused with TNF-alpha (500 microgram/kg) 5 h before perfusion. The vascular resistance increased significantly 5 h after TNF-alpha injection. The increase in vascular resistance did not seem to be mediated by a decrease in tumor nitric oxide production, as determined by perfusate nitrate/nitrite concentrations, but may be due to aggregation of leukocytes, platelets, and erythrocytes and/or endothelial consumption among the three experimental groups. The oxygen consumption was linearly dependent on the amount of available oxygen in the perfusate, whereas the glucose consumption was constant and independent of the glucose delivery rate. The present experiments provide new insights into physiological and metabolic mechanisms of action of TNF- alpha for optimization of future treatment schedules involving TNF-alpha.

Animals↗
PubMed1997

Role of nitric oxide in tumor microcirculation. Blood flow, vascular permeability, and leukocyte-endothelial interactions.

The present study was designed to define the role of nitric oxide (NO) in tumor microcirculation, through the direct intravital microcirculatory observations after administration of NO synthase (NOS) inhibitor and NO donor both regionally and systemically. More specifically, we tested the following hypotheses: 1) endogenous NO derived from tumor vascular endothelium and/or tumor cells increases and/or maintains tumor blood flow, decreases leukocyte-endothelial interactions, and increases vascular permeability, 2) exogenous NO can increase tumor blood flow via vessel dilatation and decrease leukocyte-endothelial interactions, and 3) NO production and tissue responses to NO are tumor dependent. To this end, a murine mammary adenocarcinoma (MCaIV) and a human colon adenocarcinoma (LS174T) were implanted in the dorsal skinfold chamber in C3H and severe combined immunodeficient mice, respectively, and observed by means of intravital fluorescence microscopy. Both regional and systemic inhibition of endogenous NO by N omega-nitro-L-arginine methyl ester (L-NAME; 100 mumol/L superfusion or 10 mg/kg intravenously) significantly decreased vessel diameter and local blood flow rate. The diameter change was dominant on the arteriolar side. Superfusion of NO donor (spermine NO, 100 mumol/L) increased tumor vessel diameter and flow rate, whereas systemic injection of spermine NO (2.62 mg/kg) had no significant effect on these parameters. Rolling and stable adhesion of leukocytes were significantly increased by intravenous injection of L-NAME. In untreated animals, both MCaIV and LS174T tumor vessels were leaky to albumin. Systemic NO inhibition significantly attenuated tumor vascular permeability of MCaIV but not of LS174T tumor. Immunohistochemical studies, using polyclonal antibodies to endothelial NOS and inducible NOS, revealed a diffuse pattern of positive labeling in both MCaIV and LS174T tumors. Nitrite and nitrate levels in tumor interstitial fluid of MCaIV but not of LS174T were significantly higher than that in normal subcutaneous interstitial fluid. These results support our hypotheses regarding the microcirculatory response to NO in tumors. Modulation of NO level in tumors is a potential strategy for altering tumor hemodynamics and thus improving oxygen, drug, gene vector, and effector cell delivery to solid tumors.

Adenocarcinoma↗
PubMed1997

Potential and limitations of radioimmunodetection and radioimmunotherapy with monoclonal antibodies.

UNLABELLED: Recently, we developed a physiologically based pharmacokinetic model capable of predicting antibody biodistribution in humans by scaling up from mice. By applying this model to anticarcinoembryonic antigen murine antibody ZCE025, we address several critical issues in radioimmunodetection and radioimmunotherapy, including the optimal antibody doses, the desirable antibody form for cancer detection, the optimal combinations of antibody forms and radionuclides for cancer treatment and the effectiveness of the modality. METHODS: Under the baseline conditions of a standard 70-kg man with a 20-g tumor embedded in the liver, the model was used to: (a) estimate absorbed doses in tumor and normal tissues, (b) determine dose-dependent antibody uptake in the tumor, (c) simulate tumor-to-background antibody concentration ratio and (d) calculate therapeutic ratios for different antibody forms and radionuclides. Sensitivity analysis further enabled us to determine antibody delivery barriers and to assess the modality under average and favorable tumor physiological conditions. RESULTS: By using ZCE025 under the baseline conditions, the model found that Fab was the most suitable form for cancer diagnosis, while 131l combined with F(ab')2 provided the highest tumor-to-bone marrow therapeutic ratio for cancer treatment. Sensitivity analysis showed that antibody permeability was the major barrier for antibody accretion in tumors. It also demonstrated that normal tissue antigen expression at a level lower than in the tumor had little effect on the therapeutic ratio. CONCLUSION: The model demonstrates that: (a) for radioimmunodetection, the most effective antibody form (Fab for ZCE025) was the lower mol weight form, yet not sensitive enough for hepatic metastasis detection; and (b) for radioimmunotherapy, a relatively fast-clearing antibody form (F(ab')2 for ZCE025) in combination with long half-life beta(-)-emitters was optimal, yet inadequate as the sole therapeutic modality for solid tumors.

Animals↗
PubMed1997

Early events of metastasis in the microcirculation involve changes in gene expression of cancer cells. Tracking mRNA levels of metastasizing cancer cells in the chick embryo chorioallantoic membrane.

The early events of metastasis involve multiple interactions between cancer cells and the host microcirculation during cancer cell arrest, adhesion, and extravasation. These interactions may lead to changes in gene expression of the metastasizing cancer cells, although such changes have never been demonstrated directly. To test this hypothesis, B16-F10 murine melanoma cells were injected intravenously into the chick embryo chorioallantoic membrane (CAM), and mRNA levels in the metastasizing cancer cells were evaluated by species-specific reverse transcription polymerase chain reaction. Unlike standard mouse models of experimental metastasis, the CAM model showed successful extravasation of a large number of the arrested cancer cells in the CAM microcirculation without significant cancer cell death, providing a unique opportunity to keep track of mRNA levels in cancer cells during the early phases of metastasis. Using this model, we were able to demonstrate directly the temporal induction of cancer cell genes that potentially affect metastatic efficiency, namely, Fos (5 to 60 minutes after injection), vascular permeability factor (4 to 7 hours), and urokinase plasminogen activator (> 9 hours). In conclusion, using the CAM system, we have observed an alteration of gene expression in cancer cells in the early phases of metastasis, most likely as a consequence of host-cancer cell interactions. These changes may influence the metastatic behavior of cancer cells.

Actins↗
PubMed1997

Effect of host microenvironment on the microcirculation of human colon adenocarcinoma.

It is generally accepted that the host microenvironment influences tumor biology. There are discrepancies in growth rate, metastatic potential, and efficacy of systemic treatment between ectopic and orthotopic tumors. Liver is the most common and critical site of distant metastasis of colorectal carcinoma. Tumorigenicity and efficacy of chemotherapeutic agents in colorectal tumors are different in liver and subcutaneous sites. Thus, we hypothesize that the liver (orthotopic) versus subcutaneous (ectopic) microenvironment would have different effects on the angiogenesis and maintenance of the microcirculation of colorectal tumor. To this end, we developed a new method to monitor and to quantify microcirculatory parameters in the tumor grown in the liver. Using this approach, we compared the microcirculation of LS174T, a human colon adenocarcinoma, metastasized to the liver with that of the host liver vessels and that of the same tumor grown in the subcutaneous space. In the liver metastasis model, 5 x 10(6) LS174T cells were injected into the spleen of nude mice. Four to eight weeks later, the liver with metastatic tumors was exteriorized and placed on a special stage and observed under an intravital fluorescence microscope. The dorsal skinfold chamber model was used to study the subcutaneous tumors. Red blood cell velocity, vessel diameter, density, permeability, and leukocyte-endothelial interactions were measured using fluorescence microscopy and image analysis. Vascular endothelial growth factor/ vascular permeability factor (VEGF/VPF) mRNA expression was determined by the Northern blot analysis. LS174T tumor foci in the liver had tortuous vascular architecture, heterogeneous blood flow, significantly lower vascular density, and significantly higher vascular permeability than normal liver tissue. Tumors grown in the liver had significantly lower vessel density, especially in the center coincident with central necrosis, than the subcutaneous tumors. The frequency distribution of vessel diameters of liver tumor was slightly shifted to smaller size compared with that of subcutaneous tumor. Leukocyte rolling in liver tumor was twofold lower than that in subcutaneous tumor. These physiological findings were consistent with the measurement of VEGF/VPF in that the VEGF/VPF mRNA level was lower in the liver tumor than that in the subcutaneous tumor. However, macromolecular vascular permeability in the liver tumor was significantly higher than in the subcutaneous tumor. Liver sinusoidal endothelial cells, the origin of liver tumor vessel endothelium, are known to be fenestrated and not to have a basement membrane, suggesting that the difference in endothelial cell origin may explain the difference in tumor vascular permeability in two sites. These findings demonstrate that liver microenvironment has different effects on some aspects of the tumor angiogenesis and microcirculation compared with the subcutaneous tissues. The new model/method described in this paper has significant implications in two research areas: 1) the liver microenvironment and its effect on tumor pathophysiology in conjunction with cytokine/ growth factor regulation and 2) the delivery of drugs, cells, and genes to liver tumors.

Adenocarcinoma↗
PubMed1996

Time-dependent vascular regression and permeability changes in established human tumor xenografts induced by an anti-vascular endothelial growth factor/vascular permeability factor antibody.

The hyperpermeability of tumor vessels to macromolecules, compared with normal vessels, is presumably due to vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) released by neoplastic and/or host cells. In addition, VEGF/VPF is a potent angiogenic factor. Removal of this growth factor may reduce the permeability and inhibit tumor angiogenesis. To test these hypotheses, we transplanted a human glioblastoma (U87), a human colon adenocarcinoma (LS174T), and a human melanoma (P-MEL) into two locations in immunodeficient mice: the cranial window and the dorsal skinfold chamber. The mice bearing vascularized tumors were treated with a bolus (0.2 ml) of either a neutralizing antibody (A4.6.1) (492 micrograms/ml) against VEGF/VPF or PBS (control). We found that tumor vascular permeability to albumin in antibody-treated groups was lower than in the matched controls and that the effect of the antibody was time-dependent and influenced by the mode of injection. Tumor vascular permeability did not respond to i.p. injection of the antibody until 4 days posttreatment. However, the permeability was reduced within 6 h after i.v. injection of the same amount of antibody. In addition to the reduction in vascular permeability, the tumor vessels became smaller in diameter and less tortuous after antibody injections and eventually disappeared from the surface after four consecutive treatments in U87 tumors. These results demonstrate that tumor vascular permeability can be reduced by neutralization of endogenous VEGF/ VPF and suggest that angiogenesis and the maintenance of integrity of tumor vessels require the presence of VEGF/VPF in the tissue microenvironment. The latter finding reveals a new mechanism of tumor vessel regression-i.e., blocking the interactions between VEFG/VPF and endothelial cells or inhibiting VEGF/VPF synthesis in solid tumors causes dramatic reduction in vessel diameter, which may block the passage of blood elements and thus lead to vascular regression.

Animals↗
PubMed1996

Tumor angiogenesis and interstitial hypertension.

Due to the high permeability of tumor vessels to fluids and plasma proteins, the microvascular pressure (MVP) is the principal driving force for interstitial hypertension in solid tumors; as a result, hydrostatic pressures between the microvascular and interstitial space are close to equilibrium. Based on these observations, we hypothesized that the tumor interstitial fluid pressure (IFP) should increase following the onset of angiogenesis. To this end, the relationship between IFP and tumor neovascularization was determined in the human colon adenocarcinoma (LS174T) and the murine carcinoma (MCaIV) implanted in a transparent dorsal skin fold chamber in severe combined immunodeficient mice. Three stages in the development of the tumor neovasculature were characterized by intravital microscopy. Stage I tumors were avascular, stage II was characterized by vascular sprouts and loops, and in stage III, the tumor vasculature was completely developed and blood flow was obvious. The IFP was measured with micropipettes and a servo-null system. For both tumor types, the IFP in stage I tumors was close to 0 mm Hg, and IFP increased significantly from one stage to the next. To further confirm that interstitial hypertension was associated with the development of the tumor vasculature, IFP was measured in LS174T spheroids. The mean pressure in spheroids was 0.2 +/- 0.3 mm Hg. In stage III tumors, the IFP was compared to the MVP. In MCaIV, the MVP was comparable to the IFP; however, in LS174T the MVP was significantly higher than the IFP. In conclusion, the results demonstrate that avascular tumors have atmospheric pressures and that tumor interstitial hypertension is associated with the development of the neovasculature.

Adenocarcinoma↗
PubMed1996

Fenvalerate (alpha-cyano-m-phenoxy-benzyl alpha-isopropyl-p-chlorophenyl acetate) residues in and on okra fruits.

Okra crop was sprayed with sumicidin 20E (Fenvalerate 20% EC) at the rate of 300 ml/ha (C1), 375 ml/ha (C2) and 500 ml/ha (C3). Residues in fruit samples were determined by gas chromatography (Hewlett Packard 5890 A) at different time intervals to establish the safe waiting period for Fenvalerate. The initial deposits of Fenvalerate on okra fruits for C1, C2 and C3 were 1.4 ppm, 2.8 ppm and 4.5 ppm, respectively. Seven days after spraying, the initial deposits of C1, C2 and C3 decreased to 0.03 ppm, 0.05 ppm and 0.67 ppm, respectively. The residue values of Fenvalerate on okra fruits 7 days after spraying were below the tolerance limit (0.2 ppm; Anonymous, 1978; FAO, 1980) for C1 and C2, but above it in the case of C3. Ten days after spraying, the residue values of C1, C2 and C3 were below the tolerance limit.

Chromatography, Gas↗
PubMed1996

Physiologically based kinetic model of effector cell biodistribution in mammals: implications for adoptive immunotherapy.

The goal of the present investigation was to develop a physiologically based kinetic model to describe the biodistribution of immunologically active effector cells in normal and neoplastic tissues of mammals based on the current understanding of lymphocyte trafficking pathways and signals. The model was used to extrapolate biodistribution among different animal species and to identify differences among different effector populations and between intra-arterial and systemic injections. Most importantly, the model was used to discern critical parameters for improving the delivery of effector cells. In the model, the mammalian body was divided into 12 organ compartments, interconnected in anatomic fashion. Each compartment was characterized by blood flow rate, organ volume and lymphatic flow rate, and other physiological and immunological parameters. The resulting set of 45 differential equations was solved numerically. The model was used to simulate the following biodistribution data: (a) nonactivated T lymphocytes in rats; (b) interleukin 2-activated tumor-infiltrating lymphocytes in humans; (c) nonactivated natural killer (NK) cells in rats; and (d) interleukin 2-activated adherent NK cells in mice. Comparisons between simulations and data demonstrated the feasibility of the model and the scaling scheme. The similarities as well as differences in biodistribution of different lymphocyte populations were revealed as results of their trafficking properties. The importance of lymphocyte infiltration from surrounding normal tissues into tumor tissue was found to depend on lymphocyte migration rate, tumor size, and host organ. The study confirmed that treatment with effector cells has not been as impressive as originally promised, due, in part, to the biodistribution problems. The model simulations demonstrated that low effector concentrations in the systemic circulation greatly limited their delivery to tumor. This was due to high retention in normal tissues, especially in the lung. Reducing normal tissue retention through decreasing attachment rate or adhesion site density in the lung by 50% could increase the tumor uptake by approximately 40% for tumor-infiltrating lymphocytes and by approximately 60% for adherent NK cells. Our analysis suggested the following strategies to improve effector cell delivery to tumor: (a) bypassing the initial lung entrapment with administration to the arterial supply of tumor; (b) reducing normal tissue retention using effector cells with high deformability or blocking lymphocyte adhesion to normal vessels; and (c) enhancing tumor-specific capture and arrest by modifying the tumor microenvironment.

Animals↗
PubMed1996

Plasmid-encoded degradation of p-nitrophenol by Pseudomonas cepacia.

A Pseudomonas cepacia strain RKJ 200 capable of utilising p-nitrophenol (PNP+) as the sole source of carbon, nitrogen, and energy was isolated by selective enrichment. The degradation of PNP by this strain proceeds through an oxidative route as indicated by the accumulation of nitrite molecules in the culture medium. Initial studies indicate that the degradation of PNP occurs via hydroquinone as shown by thin layer chromatography and gas chromatography studies; hydroquinone is further degraded via the beta-ketoadipate pathway. A plasmid of approximately 50 kilobase pairs was found to be responsible for carrying genes for PNP degradation in this strain. This was based on the facts that the PNP- mutants lacked the plasmid and that the PNP+ phenotype could conjugally be transferred. In addition, the same plasmid also encoded resistance to inorganic zinc ions.

Biotransformation↗
PubMed1996

Characterization of the specificities of human blood group H gene-specified alpha 1,2-L-fucosyltransferase toward sulfated/sialylated/fucosylated acceptors: evidence for an inverse relationship between alpha 1,2-L-fucosylation of Gal and alpha 1,6-L-fucosylation of asparagine-linked GlcNAc.

The assembly of complex structures bearing the H determinant was examined by characterizing the specificities of a cloned blood group H gene-specified alpha 1,2-L-fucosyltransferase (FT) toward a variety of sulfated, sialylated, or fucosylated Gal beta 1,3/4GlcNAc beta- or Gal beta 1,3GalNAc alpha-based acceptor structures. (a) As compared to the basic type 2, Gal beta 1,4GlcNAc beta-(K(m) = 1.67 mM), the basic type 1 was 137% active (K(m) = 0.83 mM). (b) On C-6 sulfation of Gal, type 1 became 142.1% active and type 2 became 223.0% active (K(m) = 0.45 mM). (c) On C-6 sulfation of GlcNAc, type 2 showed 33.7% activity. (d) On C-3 or C-4 fucosylation of GlcNAc, both types 1 and 2 lost activity. (e) Type 1 showed 70.8% and 5.8% activity, respectively, on C-6 and C-4 O-methylation of GlcNAc. (f) Type 1 retained 18.8% activity on alpha 2,6-sialylation of GlcNAc. (g) Terminal type 1 or 2 of extended chain had lower activity. (h) With Gal in place of GlcNAc in type 1, the activity became 43.2%. (i) Compounds with terminal alpha 1,3-linked Gal were inactive. (j) Gal beta 1,3GalNAc alpha- (the T-hapten) was approximately 0.4-fold as active as Gal beta 1,4GlcNAc beta-. (k) C-6 sulfation of Gal on the T-hapten did not affect the acceptor activity. (l) C-6 sulfation of GalNAc decreased the activity to 70%, whereas on C-6 sulfation of both Gal and GalNAc the T-hapten lost the acceptor ability. (m) C-6 sialylation of GalNAc also led to inactivity. (n) beta 1,6 branching from GalNAc of the T-hapten by a GlcNAc residue or by units such as Gal beta 1, 4GlcNAc-, Gal beta 1,4(Fuc alpha 1,3)GlcNAc-, or 3-sulfoGal beta 1,4GlcNAc- resulted in 111.9%, 282.8%, 48.3%, and 75.3% activities, respectively. (o) The enhancement of enzyme affinity by a sulfo group on C-6 of Gal was demonstrated by an increase (approximately 5-fold) in the K(m) for Gal beta 1,4GlcNAc beta 1,6(Gal beta 1,3)GalNAc alpha-O-Bn in presence of 6-sulfoGal beta 1,- 4GlcNAc beta-O-Me (3.0 mM). (p) Among the two sites in Gal beta 1, 4GlcNAc beta 1,6(Gal beta 1,3) GalNAc alpha-O-Bn, the enzyme had a higher affinity ( > 3-fold) for the Gal linked to GlcNAc. (q) With respect to Gal beta 1,- 3GlcNAc beta-O-Bn (3.0 mM), fetuin triantennary asialo glycopeptide (2.4 mM), bovine IgG diantennary glycopeptide (2.8 mM), asialo Cowper's gland mucin (0.06 mM), and the acrylamide copolymers (0.125 mM each) containing Gal beta 1,3GlcNAc beta-, Gal beta 1,3(6-sulfo)GlcNAc beta-, Gal beta 1,3GalNAc alpha-, Gal beta 1,3Gal beta-, or Gal alpha 1,3Gal beta- units were 153.6%, 43.0%, 6.2%, 52.5%, 94.9%, 14.7%, 23.6%, and 15.6% active, respectively. (r) Fucosylation by alpha 1,2-L-FT of the galactosyl residue which occurs on the antennary structure of the bovine IgG glycopeptide was adversely affected by the presence of an alpha 1,6-L-fucosyl residue located on the distant glucosaminyl residue that is directly attached to the asparagine of the protein backbone. This became evident from the 4-fold activity of alpha 1,2-L-FT toward bovine IgG glycopeptide after approximately 5% removal of alpha 1,6-linked Fuo.

ABO Blood-Group System↗
PubMed1996

Specificity analysis of three clonal and five non-clonal alpha 1,3-L-fucosyltransferases with sulfated, sialylated, or fucosylated synthetic carbohydrates as acceptors in relation to the assembly of 3'-sialyl-6'-sulfo Lewis x (the L-selectin ligand) and related complex structures.

Unique specificities of the cloned alpha 1,3-L-fucosyltransferases (FTs), FT III (Lewis type), FT IV (myeloid type), and FT V (plasma type), and the alpha 1,3-FTs of Colo 205 (colon carcinoma), HL 60 (myeloid), B142 (lymphoid), EKVX (lung carcinoma), and calf mesenteric lymph nodes (CMLN) were discerned with sulfated, sialylated, and/or fucosylated Gal beta 1,3/4GlcNAc beta-based acceptor moieties. (a) FT V was 1.0-, 20.8-, and 4.6-fold active in forming Lewis x, Lewis y, and 3'-alpha-galactosyl Lewis x, respectively. (b) FT III and FT V formed approximately 4-fold 3'-sulfo Lewis x, as compared to 3'-sialyl Lewis x. (c) FT IV showed great efficiency in forming 3'-sulfo Lewis x (249%) and Lewis x (345%) in mucin-type branched chains. (d) FT III, FT IV, and FT V formed 19%, 62%, and 47% 6-sulfo Lewis x as compared to Lewis x. (e) 6'-Sulfo Lewis x and 3'-sialyl-6'-sulfo Lewis x (GLYCAM ligand) were not synthesized from their immediate precursors by FT III, FT IV, or FT V. (f) FT III, FT IV, and FT V were 311%, 9%, and 188% active, respectively, with 2'-fucosyl lactose but were not active with 2'- fucosyl-6'-sulfo lactose. (g) FT III and FT V were 7.0- and 0.5-fold active in forming Lewis a as compared to Lewis x, whereas, FT IV was inactive. (h) FT III was -2.0-fold more active in forming 3'-alpha-galactosyl Lewis a than Lewis b. (i) FT III synthesized 6-sialyl Lewis a (40% efficiency as compared to Lewis a) from 6-sialyl type 1. (j) FT III did not act on 6'-sulfo or 6'-sialyl type 1 but was 106% and 22% active with 3'-sulfo and 6-sulfo type 1, respectively. (k) The Colo 205 FT activities with type 1 compounds almost paralleled that of FT III except for the low activity (9%) with Gal beta 1,3(NeuAc alpha 2, 6)GlcNAc beta-O-Bn, but with type 2 considerable differences between Colo 205 FT and FT III were noticed. (l) The alpha 1,3-FTs of CMLN, HL60, B142, and EKVX were 1.2-1.7 times active with Fuc alpha 1,2Gal beta 1,4GlcNAc beta- O-pNP and Gal alpha 1,3Gal beta 1,4 GlcNAc beta-O-Bn with respect to Gal beta 1,4GlcNAc beta-O-Al. (m) Both CMLN and HL60 FTs were 2-fold active with 3-sulfoGal beta 1,4GlcNAc in a mucin-type branch structure such as 3-sulfoGal beta 1,4GlcNAc beta 1,6(Gal beta 1,3)GalNAc alpha-O-Bn. (n) The 3'-sulfoLacNAc/acrylamide copolymer, either as an acceptor or as a competitive inhibitor, had the potential to distinguish myeloid type alpha 1,3-FT from the plasma type.

Animals↗
PubMed1996

Plasmid-mediated degradation of o-phthalate and salicylate by a Moraxella sp.

A Moraxella sp. strain VG45 capable of utilizing o-phthalate and salicylate as a sole source of carbon and energy was isolated. The degradation of o-phthalate occurs via phthalate 4,5-dioxygenase, 4,5-dihydro-4,5-dihydroxyphthalate dehydrogenase, 4,5-dihydroxyphthalate decarboxylase and protocatechuate 4,5-dioxygenase. Salicylate is degraded via salicylate 5-hydroxylase, gentisate 1,2-dioxygenase and then by a glutathione-independent maleylpyruvate hydrolase. Further, a plasmid of app. 60 kilobase pairs (kb) is involved in the degradation of the o-phthalate and salicylate and the enzymes of these two pathways are independently regulated in strain VG45.

Biodegradation, Environmental↗
PubMed1996

Effect of radiation on interstitial fluid pressure and oxygenation in a human tumor xenograft.

Elevated interstitial fluid pressure (IFP) is a pathophysiological characteristic of most human and experimental tumors and may be responsible, in part, for the poor distribution of blood-borne therapeutic agents and low blood flow rate in tumors. Recent data in cervical carcinomas in patients suggest that fractionated radiation can lower tumor IFP and increase oxygen partial pressure (pO (2)) in some patients. The goals of this study were to find the minimum dose of radiation required to modulate IFP and pO(2) and to determine the time course of IFP changes due to radiation in a preclinical model. Xenografts of the LS174T human colon adenocarcinoma were grown in the right flank of nude (BALB/c) mice. IFP and pO(2) were measured before and 24 h after graded doses of irradiation. The mean +/- SD initial IFP in untreated tumors was 12.9 +/- 0.5 mm Hg (n=109), and the range was 3.0 to 40.3 mm Hg. The mean +/- SD and median initial pO(2) were 20.2 +/- 2.4 and 11.9 mm Hg, respectively (n=37). IFP and pO(2) were independent of tumor size. Fractionated radiation lowered IFP by 2.5 mm Hg when the total dose was 10 or 15 Gy (P<0.05), but IFP did not change in the controls or the 5-Gy radiation group (P>0.05). Irradiation increased the proportion of tumors at higher oxygen tensions when compared to control tumors. The IFP and tumor volumes were followed for up to 10 days after a single dose of 10, 20, or 30 Gy of irradiation. IFP decreased for all treatment groups. The decrease was most significant for the group receiving 30 Gy. On day five following irradiation, the IFP had decreased by 35%. The changes in IFP and pO(2) occurred before any macroscopic changes in tumor volume could be observed. The radiation-induced decrease in IFP could be, in part, responsible for the increased uptake of monoclonal antibodies following single or fractionated radiation that has been reported in the literature.

Adenocarcinoma↗
PubMed1996

Chemical synthesis of a hexasaccharide comprising the Lewisx determinant linked beta-(1-->6) to a linear trimannosyl core and the precursor pentasaccharide lacking fucose.

Phenyl 2,3,4-tri-O-acetyl-6-O-chloroacetyl-1-thio-alpha,beta-mannopyranoside (5) was condensed with benzyl O-(2,3,4-tri-O-benzyl-beta-D-mannopyranosyl)-(1-->6)-2,3,4-tri-O-benzyl- alpha-D- mannopyranoside (12) in the presence of NIS-triflic acid to give, after removal of the chloroacetyl group, the key intermediate, benzyl O-(2,3,4-tri-O-acetyl-alpha-D-mannopyranosyl)-(1-->6)-O-(2,3,4-tri-O-ben zyl- beta-D-mannopyranosyl)-(1-->6)-2,3,4-tri-O-benzyl-alpha-D-mannopyranosid e (14). A similar condensation of 6 and 7 with acceptor 14, followed by the removal of protecting groups, afforded 16 and 18, respectively. These compounds are expected to be useful in specificity studies of an antibody raised against a related, synthetic antigen that we are currently investigating.

Antigens, CD↗