Lymphatic metastasis of tumour; persistent transport of cells

Summary A model of lymphatic metastasis established by injecting Walker rat carcinoma cells into the rat footpad was used to study the output of tumour cells from the footpad. The lymphatic efferent from the footpad was cannulated in a group of rats with advanced neoplasm; it was shown that the output of tumou cells was continuou over periods up to 90 min and ranged from 10²–10⁵ cells/min.Acknowledgment. This work was supported by a grant from the National Cancer Institute of Canada to C.R.F. and I.C. We are grateful to Mrs W. Kao and Mr I. Etches for meticulous technical help and to the Photographic Section, Department of Pathology for illustrations. Dr V.S. Gupta of Veterinary Physiology, University of Saskatchewan supplied the tumour for transplantation.     

Differences in luteinizing hormone release stimulated in rat anterior pituitary cells by leukotriene C4 and by gonadotropin-releasing hormone in vitro

Continuous administration of leukotriene C4 (LTC4, 10(-10) M) to superfused rat anterior pituitary cells increased LH release for 40 min only, whereas in a parallel experiment gonadotropin-releasing hormone (GnRH, 10(-9) M) evoked a continuous increase in hormone secretion. In contrast to GnRH, LTC4 did not desensitize rat anterior pituitary cells. The secretory action resulting from the administration of LTC4 (10(-10) M) was abolished for 40 min after previous stimulation. The results documented the dual action of LTC4 on LH exocytosis.     

Differences in luteinizing hormone release stimulated in rat anterior pituitary cells by leukotriene C4 and by gonadotropin-releasing hormone in vitro

Summary Continuous administration of leukotriene C₄ (LTC₄, 10^–10 M) to superfused rat anterior pituitary cells increased LH release for 40 min only, whereas in a parallel experiment gonadotropin-releasing hormone (GnRH, 10^–9 M) evoked a continuous increase in hormone secretion. In contrast to GnRH, LTC₄ did not desensitize rat anterior pituitary cells. The secretory action resulting from the administration of LTC₄ (10^–10 M) was abolished for 40 min after previous stimulation. The results documented the dual action of LTC₄ on LH exocytosis.     

Electron microscopic study of secretion of chylomicrons in the rat by enterocytes in lymphatic capillary lumen]

Rats were fed on a 20% fat diet; 30 min. or 2 hrs later intestinal jejunal cells were fixed in situ; samples were taken and processed for subsequent study by electron microscopy. Chylomicron secretion was followed from the enterocyte to the lymphatic capillary lumen. Chylomicrons entered the lamina propria through breaks in the basal membrane at intercellular space level. Their penetration into the lymphatic capillary lumen occurred through the open junctions of the endothelial cells normally kept closed by desmosomal formations.     

In situ observations of spontaneous contractions of the peripheral lymphatic vessels in the rat mesentery: effects of temperature

By means of an intracellular glass microelectrode, action potential changes were successfully recorded in situ from the endothelial cells of rat mesenteric lymphatics over the temperature range of 27-40 degrees C. The frequency of action potential and the lymphatic contraction rate correlated well with temperature.     

In situ observations of spontaneous contractions of the peripheral lymphatic vessels in the rat mesentery: Effects of temperature

Summary By means of an intracellular glass microelectrode, action potential changes were successfully recorded in situ from the endothelial cells of rat mesenteric lymphatics over the temperature range of 27–40°C. The frequency of action potential and the lymphatic contraction rate correlated well with temperature.     

Mechanical forces in lymphatic vascular development and disease

The lymphatic vasculature is essential for fluid homeostasis and transport of immune cells, inflammatory molecules, and dietary lipids. It is composed of a hierarchical network of blind-ended lymphatic capillaries and collecting lymphatic vessels, both lined by lymphatic endothelial cells (LECs). The low hydrostatic pressure in lymphatic capillaries, their loose intercellular junctions, and attachment to the surrounding extracellular matrix (ECM) permit passage of extravasated blood plasma from the interstitium into the lumen of the lymphatic capillaries. It is generally thought that interstitial fluid accumulation leads to a swelling of the ECM, to which the LECs of lymphatic capillaries adhere, for example via anchoring filaments. As a result, LECs are pulled away from the vascular lumen, the junctions open, and fluid enters the lymphatic vasculature. The collecting lymphatic vessels then gather the plasma fluid from the capillaries and carry it through the lymph nodes to the blood circulation. The collecting vessels contain intraluminal bicuspid valves that prevent fluid backflow, and are embraced by smooth muscle cells that contribute to fluid transport. Although the lymphatic vessels are regular subject to mechanical strain, our knowledge of its influence on lymphatic development and pathologies is scarce. Here, we discuss the mechanical forces and molecular mechanisms regulating lymphatic vascular growth and maturation in the developing mouse embryo. We also consider how the lymphatic vasculature might be affected by similar mechanomechanisms in two pathological processes, namely cancer cell dissemination and secondary lymphedema.     

Adenosine-5'-triphosphate levels in experimental CaNT and Fib/t tumours of varying volume and degree of hypoxia

The variation of adenosine-5'-triphosphate (ATP) content per unit mass of tumour, versus tumour volume was measured in vivo under normoxic conditions, using CaNT and Fib/t murine tumours grown in CBA and WHT mice respectively. A monotonically decreasing relation was found. Artificially induced tumour hypoxia resulting from 15 min of clamping was accompanied by reduced ATP levels.     

Monolayer cultures of normal adult rat adrenocortical cells: steroidogenic responses to nucleotides, bacterial toxins and antimicrotubular agents.

Monolayer cultures of normal rat adrenocortical cells were treated with agents which stimulate steroidogenesis by Y-1 adrenal tumour cells. Choleragen was active, whereas cyclic nucleotides other than cyclic AMP, bacterial endotoxins and antimicrotubular agents were inactive.     

Isolation of histone proteins from rat normal and tumour blood plasma

Summary Histone proteins were isolated from both normal and tumour rat blood plasma: H1, (H2b+H2a) for normal plasma and H1, H3, (H2b+H2a) and H4 for tumour one.     

A study of irrigation fluids for neurosurgery on brain primary cell cultures

Summary Primary cell cultures from newborn rat brain hemispheres were exposed to different irrigation fluids used in neurosurgery. The cells died after incubation for 5 min with hydrogen peroxide, and the number of cells was drastically decreased after 10 sec of incubation. They shrank after incubation in Elliott's artificial cerebrospinal fluid for 3 h, but the viability as determined by trypan blue exclusion test was not affected. Physiological sodium chloride, Ringer's solution and the culture medium 199 with Hank's salt had no noticeable effect on the viability or morphology of the cells.Acknowledgments. This study was supported by grants from the Medical Faculty of Göteborg and from Statens Naturvetenskapliga Forskningsråd. We want to thank Dr Åke Sellström and Dr Hans-Arne Hansson for valuable discussions.     

Periodate oxidation of lymphocyte membrane glycoconjugates]

Mouse spleen cells free of erythrocytes were suspended in PBS at a concentration of 2 X 10(7) cells/ml and mixed with an equal volume of sodium periodate in PBS for 10 min. at 4 degrees C to give a final concentration of periodate ranging from 10(-4) M to 5 X 10(-3) M. The cells were then washed and suspended (60 X 10(6) ml) in PBS containing 3H-labelled sodium borohydrate and incubated for 30 min, at 23 degrees C. Following this, the cells were washed and the pellets treated with H2SO4 0.1 N for 60 min. at 80 degrees C. Compounds liberated by such treatment, were identified by chromatography as derivates of sialic acid. The data provide direct evidence that the mitogenic effect of sodium periodate is associated to the oxidation of the sialic acid residues on the lymphocyte membrane.     

Selective killing of smooth muscle cells in culture by the ricin A-chain conjugated with monoclonal antibodies to a cell surface antigen via a dextran bridge

Monoclonal antibodies to a surface antigen of the modulated smooth muscle cells originally isolated from the rat aorta media were conjugated with ricin A-chain via an oxidized dextran bridge. The interaction of cultured cells with the conjugates obtained and with control substances was monitored following incorporation of 14C-leucine radioactivity. It was found that 14C-leucine incorporation was suppressed by 80-90% at a conjugate concentration of 10(-6)-10(-7) M. Antigen-negative cells (line IAR; rat hepatocytes) were insensitive to the conjugate at any concentration used. Control use of purified ricin A-chain, native or oxidized dextran, specific and nonspecific IgG did not affect normal 14C-leucine incorporation. The data obtained may be useful for designing targeted drug transport systems and for selective screening of modulated smooth cells in vascular pathology models in vivo.     

On the lymphatic spread of cancer

Experimental demonstration that agents promoting cellular motility and/or vascular permeability enhance the spread of tumour to regional or distant lymph nodes. Tumour emboli appear to reach the regional glands via the lymphatic channels and the distant nodes by haematogenous route.     

On the lymphatic spread of cancer

Summary Experimental demonstration that agents promoting cellular motility and/or vascular permeability enhance the spread of tumour to regional or distant lymph nodes. Tumour emboli appear to reach the regional glands via the lymphatic channels and the distant nodes by haematogenous route.     

The in vitro effect of aprotinin upon spleen cells from normal and tumour-bearing mice exposed to PPD and tumour cells

Summary A protinin (Trasylol) is shown to enhance the response of spleen cells from normal and tumour bearing mice to PPD and tumour cells. This enhancement is greater in the tumour-bearing mice.Acknowledgments. We are grateful to Bayer (U.K.) Limited for generous supplies of aprotinin. The PPD was supplied by the Ministry of Agriculture. The work was supported by a grant from the North of England Cancer Research Campaign.     

Effect of nerve stimulation on rat skeletal muscle. A study of plasma membrane

Summary The gastrocnemius muscle of the rat showed no morphological, histometric or plasma membrane changes, after sciatic nerve stimulation with a 5 mA current for 30 to 60 min, 10 mA for 30 min and 15 mA for 5 min. However, 10 mA for 60 and 200 min gave rise to mitochondrial and plasma membrane abnormalities. These changes were absent after a rest period. The results indicated the sciatic nerve stimulation at 10 mA for 60 and 200 min caused reversible changes in the rat skeletal muscle mitochondria and plasma membrane.     

Monolayer cultures of normal adult rat adrenocortical cells: Steroidogenic responses to nucleotides,bacterial toxins and antimicrotubular agents

Summary Monolayer cultures of normal rat adrenocortical cells were treated with agents which stimulate steroidogenesis by Y-1 adrenal tumour cells. Choleragen was active, whereas cyclic nucleotides other than cyclic AMP, bacterial endotoxins and antimicrotubular agents were inactive.This work was supported by the Medical Research Council of Great Britain (grant No. 970/656/B). I am grateful to MissR. Magee for technical assistance and Prof.A. M. Neville for continued support.     

Effect of nerve stimulation on rat skeletal muscle. A study of plasma membrane

The gastrocnemius muscle of the rat showed no morphological, histometric or plasma membrane changes, after sciatic nerve stimulation with a 5mA current for 30 to 60 min, 10 mA for 30 min and 15 mA for 5 min. However, 10 mA for 60 and 200 min gave rise to mitochondrial and plasma membrane abnormalities. These changes were absent after a rest period. The results indicated that the sciatic nerve stimulation at 10 mA for 60 and 200 min caused reversible changes in the rat skeletal muscle mitochondria and plasma membrane.     

Adenosine-5′-triphosphate levels in experimental CaNT and Fib/t tumours of varying volume and degree of hypoxia

Summary The variation of adenosine-5-triphosphate (ATP) content per unit mass of tumour, versus tumour volume was measured in vivo under normoxic conditions, using CaNT and Fib/t murine tumours grown in CBA and WHT mice respectively. A monotonically decreasing relation was found. Artificially induced tumour hypoxia resulting from 15 min of clamping was accompanied by reduced ATP levels.