The effects of activated macrophages on tumor target cells: Escape from cytostasis

In contrast to normal mouse peritoneal macrophages, activated macrophages almost totally inhibit [³H]TdR uptake by tumor target cells 24 hr after challenge. However, when the period of observation was extended to 48 or 72 hr, renewed [³H]TdR uptake by target cells was often, but not always, observed in the presence of activated macrophages. This apparent escape of target cells from the cytostatic effects of activated macrophages was not due to a subpopulation of resistant target cells, and autoradiographic studies revealed that target cells, inhibited from incorporating [³H]TdR by activated macrophages at 24 hr, were subsequently able to renew DNA synthesis and multiply. These results suggest that in the presence of activated macrophages, the almost total cytostasis of target cells does not necessarily mean that these cells are irreversibly damaged or killed.Escape from or maintenance of cytostasis was not peculiar to any of the target cells (L cells, EMT-6, Bladder 4934) or mouse strains (SW, C57BL, BALB/c) employed nor was it consistent with any of the forms of stimulation used for obtaining activated macrophages (Toxoplasma or Besnoitia infection; C. parvum treatment). However, the results suggest that when escape of target cells from the cytostatic effects of activated macrophages occurred, it may have been due to a qualitative or quantitative inadequacy of the population of macrophages employed.     

Unimodality,symmetry and the step-state hypothesis of electrophoretic variation in natural populations

Summary The population frequency distributions of electromorphs of polymorphic loci, when ordered by electrophoretic mobility, tend strongly and significantly to be both unimodal and symmetrical. Such distributions are predicted by all step-change models and their generality in published data can be construed as supportive of the step-change hypothesis. On the other hand, unimodality and symmetry might also be due to artifactual unit perception biases that affect the interpretation and reporting of electro-phoretic data. In any case, it appears that perceived electromorphs are highly heterogeneous.This work was supported by PHS Grant RO 1 GM 21283-O1 GEN.     

Aldolases of the lactic acid bacteria

Reciprocal qualitative and quantitative immunological experiments employing an anti-Pediococcus cerevisiae aldolase serum confirmed many of the interspecific relationships demonstrated previously among lactic acid bacteria with antisera prepared against the Streptococcus faecalis fructose diphosphate aldolase. The extent of immunological relatedness observed between the Lactobacillus and Pediococcus aldolases was markedly greater than that noted between Pediococcus and Streptococcus aldolases indicating that the pediococci share closer phylogenetic ties with the rod-shaped lactobacilli than with their spherical counterparts in the streptococci. In addition to confirming the existence of definitive, but distant, relationships between the lactic acid bacteria and certain gram positive nonsporeforming anaerobes, immunological cross-reactivity was also demonstrated between the pediococcal aldolases and those of Aerococcus viridans.This paper is dedicated with deepest appreciation to Prof. Roger Y. Stanier on the occasion of his 60th birthday in token of what his friendship and guidance have meant to me. — J. L.     

New types of islet cells in a cyclostome,Petromyzon marinus L.

Four types of acidophilic granular cells, in addition to B-cells, are identified in the islet organ of anadromous specimens of two subspecies of Petromyzon marinus by light and electron microscopy. Three of these acidophils (PI, PII and PIV-cells) occur in both the cranial and hepatic islets while a fourth type (PIII-cell) has only been found in the hepatic islet of some animals. The granules of the PI-cells stain with ponceau de xylidine, give a distinct tryptophan reaction and in ultrastructural examination show large, dense granules. The PII-cells contain unusual crystals and appear to be a non-secretory stage of the PI. The PIII-cells stain deep-red and acid fuchsin. They contain very large, dense granules and some lysosomes. PIV-cells stain selectively with phosphotungstic acid-hematoxylin and ultrastructurally, contain small, more or less dense granules. It appears that PI- and PIV-cells develop directly from B-cells, while the PIII-cells derive from PI-cells. despite their direct or indirect origin from B-cells, the PI-, PIII- and PIV-cells show characteristic features of functionally independent endocrine cells. Petromyzon marinus may be an ideal model for the understanding of phylogenetic and pathological interrelationships between islet and gastrointestinal hormones. It is clear that the interpretation of the islet organ of the cyclostomes, which has been generally considered a source of insulin only, requires a revaluation.     

Hypotonic hemolysis of human red blood cells: a two-phase process

Summary Previous use of hemolysis time measurement to determine permeability coefficients for the red blood cell membrane rested on the assumption that cells swelling in a hypotonic medium hemolyzed immediately on reaching critical volume. By preswelling red cells to various volumes prior to immersion in hemolytic solutions we extrapolate to the hemolysis time of red cells immersed at critical volume and thereby find a significant period of time during which the cells apparently remain in a spherical form prior to release of hemoglobin. Revised estimates of permeability coefficients follow from including this spherical (nonswelling) phase. In addition, the appreciation of a characteristic time period during which the membrane is under tension provides new opportunity to study physical and chemical properties of the membrane.Presented in part at the 1974 joint meeting of the Biophysical Society and the American Society of Biological Chemists.     

Identification of specificityH-2.7 as an erythrocyte antigen: Control by an independent locus,H-2G,between theS andD regions

SpecificityH-2.7 is expressed predominantly on erythrocytes and controlled by a gene that maps within theH-2 gene complex at a locus, designated asH-2G, which apparently lies between regionsS andD. Three phenotypes have been observed with respect to this antigen: a) positive by direct test and absorption (haplotypesH-2 ^f ,H-2 ^j ,H-2 ^p ,H-2 ^s ); b) positive only by absorption (H-2 ^k ); and c) negative (H-2 ^b ,H-2 ^d ,H-2 ^q ). New crossover positions have been established for severalH-2 recombinants based on classifications for theH-2G locus.     

Pancreatic islet cytology of ictaluridae (Teleostei)

Summary The endocrine pancreas of the bullhead catfish, Ictalurus nebulosus, and the channel catfish, I. punctatas was studied by light and electron microscopy. In addition to the usual A, B and D cells, a fourth endocrine cell type was consistently observed in the electron microscope. All endocrine cell types were innervated. The vesicles of most of the nerve endings were ultrastructurally different from typical adrenergic and cholinergic vesicles, strongly suggesting the possibility of a third autonomic neurotransmitter serving as a regulator of catfish islet secretion.Supported in part by PHS grant AM 11407 awarded to Dr. Bryce Munger.     

A light and electron microscopic study of myelopoietic cells in the perihepatic subcapsular region of the liver in the adult aquatic newt,Notophthalmus viridescens

Summary The liver of the newt, Notophthalmus viridescens, consists of several incompletely separated lobes of parenchymal tissue each of which is covered by a perihepatic subcapsular region (PSR) of myeloid tissue. This tissue contains neutrophils and eosinophils in various stages of differentiation. As neutrophils develop from myeloblasts to late neutrophilic myelocytes, two types of granules appear. The primary granules (type of granules formed first) are more electron dense and smaller than the secondary granules (type of granules formed later). The primary granules first appear at the stage designated early neutrophilic myelocyte, and the secondary granules appear at the stage of the maturing neutrophilic myelocyte. The eosinophils present are characterized by much larger granules than those observed in neutrophils. Cells in the PSR which superficially resemble small lymphocytes are primitive stem cells that give rise to neutrophils and eosinophils. The liver PSR is invested by a visceral peritoneum of simple squamous mesothelial cells some of which are ciliated.Supported by ACS IN-105.