M. Stone

Effects of x-radiation on growth and function of the repair blastema (granulation tissue). II. Measurements of angiogenesis in the Selye pouch in the rat.

SummaryThe Selye pouch technique has been used to stimulate growth of the repair blastema and angiogenesis and measure radiosensitivity of capillary blood vessels in the subcutis. Measurements of radiation damage to the tissue were based on (i) weight per unit area and corresponding DNA content of the repair blastema, (ii) the volume of blood produced in the pouch by angiogenesis and (iii) vascular macrocolony counts. Colony counts gave a D0 value of ∼240 rads for single-dose and ∼180 rads recovery for split-dose irradiation. No significant difference was observed for single doses of irradiation given shortly before or after raising the pouches. Increasing the interval between irradiation of intact skin and raising of the pouch, was associated with rapid and marked repair of radiation damage; a delay of 2–3 weeks resulted in a dose-reduction factor of 500–625 rads for single doses of 1500–1800 rads given to intact skin. Local irradiation of an established pouch with a single large dose (2–4 krads) rapidly...

Promotion of Growth of Tumour Cells in Acutely Inflamed Tissues

Acute inflammatory reactions were induced in rats by the intravenous injection of cellulose sulphate (CS) or an extract of normal rat lung homogenate (LH), or by intraperitoneal injections of Compound 48/80. These treatments greatly increased survival and clonogenic growth in the lungs of rats of intravenously injected allogeneic W-256 and Y-P388 tumour cells. Increase in the dose of intravenously injected CS caused a logarithmic increase in colony forming efficiency (CFE) of tumour cells in the lungs. CFE was not stimulated by the intravenous injection of rats with pharmacological mediators of inflammation (histamine, 5-hydroxytryptamine, bradykinin and prostaglandins PGE1 and PGF2α) which are released from tissues by agents which induce inflammation. Stimulation of CFE by CS occurred in adrenalectomized rats but was inhibited by treatment of rats with an anti-inflammatory steroid, dexamethasone. CFE was stimulated by CS in tumour immunized rats; the inflammatory state did not prevent the expression of immunity but “rescued” a proportion (approximately 20%) of the injected tumour cells from immunodestruction in the lungs. A higher proportion of tumours grew in the paws of rats when a small number of W-256 cells were injected interdigitally into the acute inflammatory swellings produced by the local injection of paws with LH or CS.CS is a “synthetic heparin” which causes marked prolongation of blood clotting time and also increases fibrinolytic activity of the blood. Anticoagulant treatment of rats with heparin did not affect CFE. Thus, there was no direct correlation between blood clotting time and CFE of blood borne tumour cells in the rat.The mechanisms which may be responsible for the nonspecific growth promoting effects of inflammatory reactions induced by various types of tissue injury on tumour induction and growth are discussed.

Reactions of the tumour bed to lethally irradiated tumour cells, and the Revesz effect.

Subdermal inoculation of the foot of the rat with lethally irradiated (LI) Walker tumour (W256) cells, mixed with viable (V) W256 cells, decreased the latent period for initiation of allogeneic tumour growth without significantly affecting its rate. This Révész effect decreased with increase in the number of inoculated V cells, and with decrease in age of recipient. LI cells of a different (Y-P388) rat tumour exerted a Révész effect, even in recipients which had been immunized with LI (Y-P388) tumour cells. Local pre-irradiation of the site of inoculation of V cells decreased both the latent period and rate of tumour growth. It acted independently of a Révész effect, and the decrease in tumour growth rate was partly due to emigration of V cells from the inoculum, producing metastases. LI, but not heat-killed cells, induced prolonged swelling of the tumour bed in unimmunized and tumour-immunized rats, which, unlike inflammatory swelling, was inhibited by pre-irradiation of the foot. It is postulated that the Révész effect is due to enhancement of survival of V cells by trophic substances which are principally elaborated by LI (AND V) cells, but also by the tumour bed, due to innate growth and trophic reactions of its tissues to the presence of tumour cells.

Effects of x-radiation on growth and function of the repair blastema (granulation tissue). I. Wound contraction.

Pre-operative local irradiation of intact rat skin given immediately before wounding caused dose-dependent reductions in the rate of wound contraction, largely by delaying and inhibiting growth of the repair blastema. When the dose was fractionated, evidence of recovery of sublethal damage STA(D/ sub 2/- D/sub 1/) approx equal 250 rads! was obtained. The effect of pre- operative irradiation was decreased by increasing the time between irradiation and wounding. Pre-operative local irradiation of the skin, partly shielded by a lead grid or by a lattice of lead discs, with large single doses (4 to 8 kR), caused no reduction in the rate of wound contraction and showed that spatial discontinuity of blastemal tissues did not prevent integration of function. Partial shielding of the margin or base of a freshly-made wound during irradiation showed that the sphincter-like concentration of blastema produced at the periphery of an open wound principally effected contraction. When the radiation was given postoperatively to a contracting wound (i.e., after the repair blastema had developed) the rate of contraction was not decreased. The bearing of the radiobiological findings on the mechanism of wound contraction and their relevance to combined treatment by radiotherapy and surgery was discussed. (auth)

Effect of X-radiation on Salivary Gland Growth in the Rat: IV. Relative Effects of Local Irradiation on Growth, Regressive and Secretory Phases of Sialadenotrophism

SummaryAdaptive growth of salivary tissues in the rat (growth phase of sialadenotrophism), induced by treatment with isopropylnoradrenaline (ISOP), was principally due to the hypertrophy of acinar cells assisted by a relatively short and limited phase of acinar-cell hyperplasia (cell division) which caused corresponding increases in total glandular DNA. This hyperplastic component of growth was radiosensitive. Increases in glandular protein and RNA due to cell hypertrophy were radioresistant. Decreases in gland-weight, protein, RNA and DNA, which occurred rapidly after treatment with ISOP had been terminated (regression phase), were due to (a) regression of cell hypertrophy and (b) loss of super-numerary acinar cells that had accumulated during the growth phase. Local irradiation (1500 rads) failed to affect the rates of regression of hypertrophy and cell loss. Secretion and resynthesis of salivary enzyme (amylase) by parotid gland, which had become enlarged in rats treated with ISOP, were similarly radio...

Rapid and accurate measurement of growth of solid tumours and changes in the tumour bed in the rat by the technique of volumetric displacement.

An apparatus which has been widely used in rats for measuring swelling of the foot induced locally by inflammatory agents has been adapted to measure rapidly, accurately and objectively, the growth of tumour cells transplanted to the foot, and the reactions of the normal tissues (tumour bed) to tumour growth. General features on the apparatus and the techniques used are described. Examples are provided of preliminary measurements made of normal growth of the foot, reactions of the foot to two injurious agents (histamine and Corynebacterium parvum) and of growth of allogeneic (W256) tumour cells.

Effects of X-radiation on Growth and Function of the Repair Blastema (Granulation Tissue): III. Measurements of Pharmacodynamic Activity in Vitro

SummaryThe development of contractility during growth of granulation tissue (GT) in unirradiated and irradiated skin of the rat has been studied. The Selye pouch method was used to grow GT, and the in vitro technique of Majno et al. (1971) to measure pharmacodynamic responses to various drugs. In particular, the reactions of the tissue to 5-hydroxytryptamine and other inflammatory autacoids and to colchicine and related spindle poisons were studied. Irradiation delayed the onset of contractility and its development by reducing growth of GT; it did not affect affinity or intrinsic activity of receptors to agonists which cause contraction of this tissue, but tended to increase the strength of contraction. These observations are discussed in relation to the roles of microtubules and microfilaments in the control of cell tone and of the cellular mechanisms underlying wound contraction.