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Showing papers by "Rakesh K. Jain published in 1984"


Journal Article
TL;DR: Differential flow response in individual microvessels was used to develop a theoretical framework relating various mechanisms of blood flow modifications due to hyperthermia, which appeared to be bimodal functions of temperature.
Abstract: RBC velocity and vessel lumen diameter were measured in individual microvessels in normal (mature granulation) and neoplastic (VX2 carcinoma) tissues grown in a transparent rabbit ear chamber. Blood flow rates were determined before, during, and after local hyperthermia treatments at 40–52° for 1 hr. Blood flow in normal tissue increased dramatically with temperature, but stasis occurred at higher temperatures and/or longer durations of heating. In tumors, blood flow rate did not increase as much, and stasis occurred at lower levels of hyperthermia. Both the magnitude and the time of maximum flow appeared to be bimodal functions of temperature. That is, both of these parameters increased with temperature up to a certain critical temperature, and then decreased at higher temperatures. This critical temperature was approximately 45.7° in normal tissue and 43.0° in tumors. Normal tissue required temperatures greater than 47° to bring about vascular stasis in less than 1 hr, while stasis occurred in tumors in the same time frame at temperatures greater than 41°. Normal tissue could increase its maximum flow capacity up to 6 times its preheating value, while neoplastic tissue could only double its maximum flow capacity. This differential flow response in individual microvessels was used to develop a theoretical framework relating various mechanisms of blood flow modifications due to hyperthermia.

323 citations


Journal Article
TL;DR: Macromolecular transport in tumor tissue was hindered to a lesser extent than in normal tissue, which is consistent with reports of reduced contents of glycosaminoglycans, and markedly large interstitial space in tumors.
Abstract: Extravascular transport of fluorescein isothiocyanate-conjugated bovine serum albumin and a graded series of fluorescein isothiocyanate-dextrans from Mr 19,400 to 71,800 were studied in both normal tissue (granulation) and tumor (VX2 carcinoma) grown in a rabbit ear chamber. Sodium fluorescein was used as a representative small molecule. A one-dimensional diffusion model adequately described extravascular transport in both normal and tumor tissue. Measured diffusion coefficients showed a relationship with molecular size which progressively deviates from that of free diffusion in water, with values for albumin being significantly reduced from that for a dextran of equivalent size. Macromolecular transport in tumor tissue was hindered to a lesser extent than in normal tissue, which is consistent with reports of reduced contents of glycosaminoglycans, and markedly large interstitial space in tumors. Diffusion coefficients for dextran were found to vary with molecular weight according to the expression, D = a(Mr)b, in both normal tissue (a = 10(6) and b = -2.96) and tumor (a = 2.51 X 10(-2) and b = 1.14).

295 citations


Journal ArticleDOI
TL;DR: The objective of this paper is to summarize the data on tumor blood flow rate during normothermia and hyperthermia, and to discuss the use of pharmacological agents in modifying the tumorBlood flow rate for therapeutic benefits.
Abstract: Abstruct-The differential blood flow rateof normaland tumor tissues plays a critical role in determining the effectiveness of hyperthermia alone or in combination with radiation and chemotherapy. The objective of this paper is to summarize the data on tumor blood flow rate during normothermia and hyperthermia, and to discuss the use of pharmacological agents in modifying the tumor blood flow rate for therapeutic benefits. After a brief review of various physical, physiological, biochemical, and biological factors that determine the effectiveness of hyperthermia in cancer treatment, various methods of blood flow measurements will be outlined. The following section will be devoted to the tumor blood flow rate during normothermia. Next will be discussion of changes in tumor blood flow rate at elevated temperatures. Finally, the possibility of modifying tumor blood flow rate by the use of vasoactive agents will be discussed. Throughout this paper, outstanding problems in the measurements and alterations of blood flow will be identified and some directions for future research will be suggested.

240 citations


Journal ArticleDOI
TL;DR: The extracellular pH and temperature of Walker 256 carcinoma and of normal subcutaneous tissue were measured continuously in unanesthetized female Sprague-Dawley rats for up to 20 hours following glucose or galactose administration and response of large ulcerated tumors was not as uniform.
Abstract: The extracellular pH and temperature of Walker 256 carcinoma and of normal subcutaneous tissue were measured continuously in unanesthetized female Sprague-Dawley rats for up to 20 hours following glucose or galactose administration. The pH was monitored with flexible glass electrodes contained in micropore chambers implanted in the flank of a rat. Temperature was measured with miniature thermistor probes incorporated in the tumor or in subcutaneous tissue. The pH in the untreated Walker 256 carcinoma decreased linearly from approximately 7.3 to 6.2 with increasing tumor mass up to 50 g. Administration of glucose (6 g/kg body wt, ip) in tumor-bearing rats increased glucose concentrations in blood and tumor, as well as lactic acid concentration in tumor, and had no significant effect on lactic acid concentration in blood. Plasma volume was not affected by either glucose or galactose loading as compared to that in rats given saline alone. However, the blood viscosity increased by up to 30% within 30 minutes after galactose injection, but not after glucose injection, and this significant difference in viscosities persisted for approximately 6 hours after glucose and galactose injections. In small tumors (less than 10 g), a decrease of up to 1 pH unit was observed within 6 hours after glucose administration, and the return of pH to pretreatment values began about 10 hours after glucose injection. Response of large ulcerated tumors (greater than 20 g) was not as uniform; the pH decreased by about 0.5 to 1 pH unit for only a brief period. After galactose injection, pH in some tumors remained unchanged, whereas in others an average decrease of about 0.2 pH units was observed. The pH in normal tissue was not affected by glucose or galactose administration. Both glucose and galactose decreased tumor temperature by about 7 degrees C.

99 citations


Journal ArticleDOI
TL;DR: A one-dimensional model of diffusion adequately described interstitial transport and sodium fluorescein and albumin agreed with a fiber-matrix model, whereas the interstitial diffusion of dextrans more closely corresponded to a pore model.
Abstract: Concentration-time profiles of fluorescein isothiocyanate (FITC)-conjugated bovine serum albumin and a graded series of FITC-dextrans of 20,000-70,000 molecular weight were measured within the erythrocyte-free plasma layer in individual vessels and at various positions within the interstitial tissue space of mature granulation tissue grown in a rabbit ear chamber. Sodium fluorescein was used as a representative small molecule. The plasma pharmacokinetic data were found to follow a biexponential decay in time. A one-dimensional model of diffusion adequately described interstitial transport. Interstitial diffusion coefficients decreased progressively with Stokes-Einstein radius with values for albumin being significantly reduced from that for a dextran of equivalent hydrodynamic radius. Interstitial diffusion of sodium fluorescein and albumin agreed with a fiber-matrix model, whereas the interstitial diffusion of dextrans more closely corresponded to a pore model.

67 citations


Journal ArticleDOI
TL;DR: No significant differences were observed in the measured dielectric properties of normal and neoplastic tissues, presumably due to the high water content of both types of tissues.
Abstract: Dielectric properties of five rat mammary carcinomas, one rat glioma, and rat muscle were measured in vitro at 37 and 43 °C over a frequency range of 1 MHz-1 GHz. No significant differences were observed in the measured dielectric properties of normal and neoplastic tissues, presumably due to the high water content of both types of tissues.

40 citations


Journal ArticleDOI
TL;DR: Biochemical and restriction endonuclease analysis of the wild-type and mutant strains showed that the structural and/or regulatory genes for 3,5-xylenol metabolism were encoded within a 130–140 kb region of pRA500.
Abstract: SUMMARY: Pseudomonas putida NCIB 9869 carries a transmissible plasmid pRA500 of approximately 500 kb which encodes the degradation of 3,5-xylenol via a gentisate pathway. Several mutant strains which were unable to utilize 3,5-xylenol were isolated and these strains either carried deleted derivatives of pRA500 or lacked plasmid DNA. Biochemical and restriction endonuclease analysis of the wild-type and mutant strains showed that the structural and/or regulatory genes for 3,5-xylenol metabolism were encoded within a 130–140 kb region of pRA500 and that, with the exception of the first enzyme of the pathway, 3,5-xylenol methylhydroxylase, all the enzymes were encoded within a 50–70 kb segment of that region. pRA500 also encoded for resistance to inorganic mercuric ions; the genes for this phenotype were located separately from those for the degradation of 3,5-xylenol.

28 citations





Journal ArticleDOI
TL;DR: This paper showed that pyrex glass beads can increase the surface area of lipid-glass contact by more than 100 times in the presence of polyethylene glass beads, which is more than 5 times larger than in the control experiments without glass beads.

Journal ArticleDOI
TL;DR: Observation directe de l'etat triplet du compose cite dans le titre par spectroscopie RPE et etude de ses comportements thermiques as discussed by the authors.
Abstract: Observation directe de l'etat triplet du compose cite dans le titre par spectroscopie RPE et etude de ses comportements thermiques


Journal ArticleDOI
TL;DR: In this paper, the plasma pharmacokinetics of sodium fluorescein, conjugated bovine serum albumin and a graded series of dextrans of 19,400 to 71,800 MW were monitored continuously using a noninvasive photometric technique in individual blood vessels of tissue grown in a rabbit ear chamber.
Abstract: Plasma pharmacokinetics of sodium fluorescein, fluorescein isothiocyanate conjugated bovine serum albumin, and a graded series of dextrans of 19,400 to 71,800 MW were monitored continuously using a noninvasive photometric technique in individual blood vessels of tissue grown in a rabbit ear chamber. The data obtained were fitted with a two-compartment open model to obtain an effective permeability and an effective clearance. Both parameters decreased with increasing molecular radius for dextrans. Values for albumin were considerably less than expected on the basis of molecular radius, presumably due to the configuration, charge, and binding characteristics of albumin.

Journal Article
TL;DR: Ten established cases of lepromatous leprosy with laryngeal involvement are reported, and their clinical and histopathological findings are discussed with a brief review of the literature.
Abstract: Ten established cases of lepromatous leprosy with laryngeal involvement are reported, and their clinical and histopathological findings are discussed with a brief review of the literature.

01 Jan 1984
TL;DR: Values for albumin were considerably less than expected on the basis of molecular radius, presumably due to the configuration, charge, and binding characteristics of albumin.
Abstract: Plasma pharmacokinetics of sodium fluorescein, fluorescein isothiocyanate conjugated bovine serum albumin, and a graded series of dextrans of 19,400 to 71,800MW were monitored continuously using a noninvasive photometric technique in individual blood vessels of tissue grown in a rabbit ear chamber. The data obtained were fitted with a two-compartment open model to obtain an effective permeability and an effective clearance. Both parameters decreased with increasing molecular radius for dextrans. Values for albumin were considerably less than expected on the basis of molecular radius, presumably due to the configuration, charge, and binding characteristics of albumin.


Journal ArticleDOI
01 Oct 1984
TL;DR: In this article, general dispersion equations for planar, thin viscoelastic films between membranes are developed, and the effects due to the membrane tension, bending elasticity and permeability, as well as those of the disjoining pressure and the viscoelingity of the films, on the conditions for film rupture and on the film breaking time are considered.
Abstract: Differential equations which describe the dynamics of thin viscoelastic films, behaving as Maxwell or Kelvin bodies between permeable and deformable membranes are derived. General dispersion equations for planar, thin viscoelastic films between membranes are developed. The effects due to the membrane tension, bending elasticity and permeability, as well as those of the disjoining pressure and the viscoelasticity of the films, on the conditions for film rupture and on the film breaking time are considered. It is proposed that the film stability may be a determinant of the kinetics of membrane fusion. The theoretical estimates are in qualitative agreement with available experimental data.

Journal Article
TL;DR: A case of tuberculoid leprosy with complete depigmentation on its active margins, in a predisposed individual to vitiligo is presented and the postulated mechanism of hypopigmentation vis-a-vis leproSy lesions is discussed in brief.
Abstract: A case of tuberculoid leprosy with complete depigmentation on its active margins, in a predisposed individual to vitiligo is presented. The postulated mechanism of hypopigmentation vis-a-vis leprosy lesions is discussed in brief in the context of the presenting unusual association.