Showing papers by "Rakesh K. Jain published in 1987"

Transport of Molecules in the Tumor Interstitium: A Review

Abstract: The transport of fluid and solute molecules in the interstitium is governed by the biological and physicochemical properties of the interstitial compartment as well as the physicochemical properties of the test molecule. The composition of the interstitial compartment of neoplastic tissues is significantly different from that of most normal tissues. In general the tumor interstitial compartment is characterized by large interstitial space, high collagen concentration, low proteoglycan and hyaluronate concentrations, high interstitial fluid pressure and flow, absence of anatomically well-defined functioning lymphatic network, high effective interstitial diffusion coefficient of macromolecules, as well as large hydraulic conductivity and interstitial convection compared to most normal tissues. While these factors favor movement of macromolecules in the tumor interstitium, high interstitial pressure and low microvascular pressure may retard extravasation of molecules and cells, especially in large tumors. These differences in transport parameters have major implications in tumor growth and metastases, as well as in tumor detection and treatment.

Transport of molecules across tumor vasculature.

Abstract: The vascular-extravascular exchange of fluid and solute molecules in a tissue is determined by three transport parameters (vascular permeability, P, hydraulic conductivity, Lp, and reflection coefficient, σ); the surface area for exchange, A; and the transluminal concentration and pressure gradients. The transport parameters and the exchange area for a given molecule are governed by the structure of the vessel wall. In general, tumor vessels have wide interendothelial junctions; large number of fenestrae and transendothelial channels formed by vesicles; and discontinuous or absent basement membrane. While these factors favor movement of molecules across tumor vessels, high interstitial pressure and low microvascular pressure may retard extravasation of molecules and cells, especially in large tumors. These characteristics of the transvascular transport have significant implications in tumor growth, metastasis, detection and treatment.

Secondary tuberculosis of the skin. Clinical features and problems in laboratory diagnosis.

Abstract: One hundred patients with secondary skin tuberculosis–59 with lupus vulgaris (LV), 27 with scrofuloderma (SD), and 14 with tuberculosis verrucosa cutis (TVC)–were included in this study. The buttocks and lower limbs were seen to be important sites of involvement in LV, besides the occurrence over the face. An active focus of tuberculosis was present in 18, a past history of pulmonary tuberculosis in 8, and intrafamilial tuberculous infections in 21. Histopathology and culture for Mycobacterium tuberculosis were done in all the cases. Guinea pig inoculation was done in 11. The poor results of these investigations have been highlighted and discussed with reference to studies done in the past by other workers. The need for improvement in laboratory techniques is suggested.

Effect of Glucose and Galactose on Microcirculatory Flow in Normal and Neoplastic Tissues in Rabbits

Abstract: Red blood cell (RBC) velocity and vessel lumen diameter were measured in individual microvessels of both normal (mature granulation) and neoplastic (VX2 carcinoma) tissues grown in a transparent ear chamber prior to and following glucose and galactose injections (6 g/kg i.v.) in anesthetized rabbits. RBC velocity was measured using the dual-slit photometric technique and the diameter of the vessels was determined using an image shearing device. From these measurements, the mean volumetric flow rates in the individual vessels were determined. Glucose produced a 90% decrease in RBC velocity and blood flow rate in the tumor at 65 min postinjection without modifying the flow in the normal tissue. Galactose, on the other hand, decreased RBC velocity and blood flow in the tumor and normal tissues by approximately 90 and 55%, respectively, at 65 and 5 min postinjection. Neither glucose nor galactose caused any statistically significant changes in vessel diameter, WBC adhesion to vessels, microvascular permeability, or systemic viscosity. Results suggest that the mechanism responsible for flow reduction in tumors due to glucose and galactose are both systemic and local. Systemic mechanisms include reduction and redistribution of the cardiac output. Local mechanisms for glucose include blockage of rigid RBC in the tortuous vasculature of tumor and increase in local blood viscosity also due to RBC rigidity. Increase in RBC rigidity is caused by glucose itself as well as by low pH in tumors. Results also show that the local mechanisms responsible for blood flow reduction following galactose injection differ from those responsible for the reduction following glucose injection.

Molecular microbial ecology of a naphthalene-degrading genotype in activated sludge

Abstract: The concentration of cells in an activated sludge system containing a gene known to participate in degradation of naphthalene was experimentally related to the biotransformation and mineralization of naphthalene. The gene probe analysis for the naphthalene catabolic genotype was more sensitive in this system than other naphthalene degrader microbial analysis methods for naphthalene catabolic cells. Other live cells present were 1000-10,000-fold more numerous than the genotype. Naphthalene biotransformation and mineralization rates fell when the mean value of genotype replicates dropped below 10/sup 7/ genotypically positive cells/mL. The ability to enumerate a critical genotype and relate it to enzymatic activity in a mixed culture suggests an improved capability for system understanding at the ecological level and the potential for process control at the genotype level.

Effect of glucose and galactose on red blood cell membrane deformability

Abstract: The effect of glucose and galactose on the membrane deformability of red blood cells (RBC) suspended in isotonic solution was determined using micropipette aspiration technique. In this method, a negative pressure was applied to the RBC membrane via a micropipette and the resulting deformation was analyzed using a Kelvin model to yield a membrane elastic modulus E. When glucose concentration was increased from 0 to 0.3 M/dm3 in the extracellular media, E increased seven-fold (p less than 0.0001) with most increase occurring in the 0-0.05 M/dm3 range. The increase in E due to glucose was not completely reversible. The time constant of increase in E was about 14 minutes. Whereas, galactose had no significant effect on the membrane elasticity up to a concentration of 0.3 M/dm3. Increase in the RBC membrane rigidity in the presence of glucose may be due to binding of glucose to the membrane and intracellular proteins. The results obtained may be important for explanation of decrease in tumor blood flow during hyperglycemia.

A Theoretical Model for Water Flux Through the Artery Wall

Abstract: A two layer model for water flux through the artery is studied using a mathematical model based on the theory for the consolidation of water saturated soils. The matrix is considered to be constituted by two layers with different permeabilities and different elastic constants and the two systems of equations are coupled with the condition of continuity of pressure, total stress, solid displacement and fluid seepage velocity at the interface. The luminal pressure is considered to be harmonic in time. Exact solutions are obtained for displacements and pressures in both the layers. For large consolidation times, large pressure gradients are found to exist near the boundaries and at the interface. The heterogeneous model may not only be useful to understand the mechanics of transport in the physiological system but it will also help the bioengineers to choose proper implant materials to design artificial vascular organs for the purpose of prosthesis.

Analysis of diffusive and convective recovery of fluorescence after photobleaching—effect of uniform flow field

Abstract: Fluorescence Recovery After Photobleaching (FRAP) is used to monitor the relaxation of concentration profiles after various imposed concentration fields. A theoretical analysis is conducted to quantify convective and diffusive transport and determine their contributions to fluorescence recovery in a perfused medium. Four different photobleach geometries—line, periodic pattern, uniform circular spot and Gaussian spot—are studied. It is shown that a spatially-averaged fluorescence profile (as would be the output of a photomultiplier) is inadequate in distinguishing convection from diffusion except in cases of large convection. In order to characterize both diffusive and convective effects, it is necessary to study the detailed concentration profile as a function of space and time.

Matting of the Hair Due to Onic Detergent.

Abstract: A 27 year old developed matting of her hair after using 5% cetrimide lotion for dandruff.

Type 1 (reversal) lepra reaction in borderline leprosy with unusual clinical presentation--a case report.

Abstract: A male 26 years old patient with BB type of leprosy was encountered with a typical clinical presentations of up-grading (reversal) Type 1 Lepra Reaction. These included sudden appearance of tender, erythematous nodular eruptions mimicking ENL, severe constitutional symptoms like high grade fever, malaise, vomiting, epistaxis, joint pain and tenosynovitis simulating Type 2 Lepra Reaction. To the best of our knowledge, this may be the first such case in our hand.

Synthetic Studies in Carbohydrates. Part 44. A Synthesis of Methyl 3-O-α-D-Mannopyranosyl-α-D-mannopyranoside and Related Disaccharides.

Abstract: The key intermediates (IVa) and (IVb) are synthesized from the protected mannosides (I) as outlined in the reaction scheme.

Synthetic Studies in Carbohydrates. Part 46. Synthesis of Some D-Mannosyl-disaccharides Containing D-Mannose 6-Phosphate Residues.

Abstract: The disaccharides mentioned in the title are prepared by two methods: 1. condensation of a phosphorylated bromide, e.g. (II), with a glycosyl acceptor such as (III) yields the target compound (IV), 2. direct phosphorylation of the disaccharides (V) produces the monophosphorylated derivatives (VI).