Evaluation of serum levels of cytokines and intercellular adhesion molecule-1 (ICAM-1) in astrocytic tumours

Soluble form of intercellular adhesion molecules (sICAM) are increased in serum of many inflammatory diseases and tumours: the expression of such molecules is regulated by cytokines. In the present paper serum levels of interleukin-2 (IL-2), soluble interleukin-2 receptor (sIL-2R) and sICAM-1 were evaluated in patients with glioma compared with different tumours (lung and kidney carcinoma) in order to investigate the compromise of the immune system in these malignancies and to understand the host defence mechanisms. 14 cases of astrocytomas (WHO grade II, III), 20 cases of glioblastomas (GBL, WHO grade IV), 5 cases of lung carcinoma and 6 cases of kidney carcinoma were studied; the results were compared with 15 healthy controls. IL-2, sIL-2R, sICAM-1 concentrations were assessed by an enzyme-linked immunosorbent assay (ELISA) technique. The results were analyzed by Student's t test. Our findings showed that serum levels of IL-2 and sIL-2R were increased in all cancer patients; on the contrary, sICAM-1 serum levels were not significantly increased in GBL and astrocytoma patients. The increased values of IL-2 and sIL-2R are in agreement with a depression of the immune reactivity in patients with glioblastoma and astrocytoma, as reported in literature. On the contrary the levels of sICAM-1 are unchanged in astrocytic tumours while patients with kidney carcinoma presented the higher levels and an unfavourable prognosis.

Styrene hepatotoxicity in rats treated by inhalation or intraperitoneally: a structural investigation

The purpose of this study was to investigate the toxicity of styrene in the liver of adult rats treated either by inhalation of styrene vapour (300 ppm, 6 h/d, 5 d/wk, for 2 wk) or intraperitoneally with different styrene doses (4, 40, 400 mg/Kg) for 3 consecutive days. Using a light microscope, some alterations of liver parenchyma and sinusoid dilation were noticed, more marked in the group treated with the intraperitoneal administration of the chemical. Using an electron microscope, some additional changes were observed (once again, more marked in the latter group of rats): a) an increase in the content of lipids inside hepatocytes, and b) the rise of intracytoplasmic, intercellular and perisinusoidal collagen fibres. Therefore, cell damage and functional disturbance of sinusoids due to perisinusoidal fibrosis are apparent in the liver of both groups of rats exposed to styrene treatment, but these changes are definitely more significant in those subjected to intraperitoneal administration.

Hemopoiesis in the liver of adult tumor-bearing mice

In the liver of adult mice bearing an Ehrlich carcinoma on the leg, progressively hypoxic and displaying reactive hepatitis but not metastatic dissemination, extramedullary hemopoiesis was detected. Electron microscopy revealed mainly erythropoietic islands and scattered megakaryocytes in maturation stages up to the platelet-releasing phase. Erythropoietic cells expressed an embryonic-type of hemoglobin, which is more adequate to oxygenate hypoxic environments than the adult type. They were positive for the peroxidase reaction due to the presence of hemoglobin and could furthermore be visualized by the blue-excited red autofluorescence of protoporphyrin IX. Extramedullary hemopoiesis, one of the various examples of reactivation of fetal features in the liver associated with carcinogenesis, is supposed to be compensatory for the loss of blood cells induced by the tumor. Reviewing this process has the purpose of raising the question whether the fetal features are better adapted than adult ones to the metabolic and physiological characteristics of a tumor-influenced organism.

Enzyme histochemical studies on tumor blood vessels

The oxygenation, the growth rate and the metastatic potential of a solid tumor depend on its vascularization and, in particular, on angiogenesis; a therapeutic approach affecting angiogenesis has been suggested as an alternative to conventional ones. Especially the study of the metabolism in the cells of the vessel wall should be a useful prerequisite for this approach. In this connection, an enzyme histochemical study was performed to characterize the blood vessels in a solid tumor (Ehrlich carcinoma). The following enzymes were considered: (a) alkaline phosphatase, involved in the transcellular phosphate transport and in the response to inflammatory and growth promoting factors; (b) dihydrofolate reductase, involved in the metabolism of tetrahydrofolate (for the synthesis of nucleic acids and the metabolism of serine and glycine); (c) purine nucleoside phosphorylase, involved in the degradation of purines and, in particular, of extracellular ATP and ADP; (d) xanthine oxidoreductase, engaged in the same degradation path and leading to the formation of urate, a strong antioxidant. Various patterns of enzyme activities were observed in the vessel wall. In particular, thin linear capillaries (presumed to be host capillaries penetrating the tumor) were identified for the intense positivity of alkaline phosphatase, dihydrofolate reductase and purine nucleoside phosphorilase; tortuous capillaries with variable diameters (presumed to be induced by angiogenesis from the host vessels) were negative for the alkaline phosphatase and expressed an heterogeneous pattern for the dihydrofolate reductase. All the data suggest a different vessel behaviour concerning the response to cytokines and to inflammatory stimuli.

Increase in liver pigmentation during natural hibernation in some amphibians

The amount/distribution of liver melanin in 3 amphibian species (Rana esculenta, Triturus a. apuanus, Triturus carnifex) was studied during 2 periods of the annual cycle (summer activity-winter hibernation) by light and electron microscopy, image analysis and microspectrofluorometry. The increase in liver pigmentation (melanin content) during winter appeared to be correlated with morphological and functional modifications in the hepatocytes, which at this period were characterised by a decrease in metabolic activity. These findings were interpreted according to the functional role (e.g. phagocytosis, cytotoxic substance inactivation) played by the pigment cell component in the general physiology of the heterothermic vertebrate liver and, in particular, in relation to a compensatory engagement of these cells against hepatocellular hypoactivity during the winter period.

Comparison of K(+)-p-nitrophenyl phosphatase activity in the urinary bladder of the frog Rana esculenta during hibernation and active life

We have studied effects of hibernation on the frog urinary bladder, an organ involved in water and ion transepithelial transport and taking part in osmoregulation. We have demonstrated K(+)-p-nitrophenyl phosphatase activity (an enzyme involved in ion and water transport) both in active and hibernating frogs. Most of the reaction product deposition was found on basolateral membranes of granular cells of the urinary bladder epithelium during all seasons. Therefore, it seems likely that this organ, unlike organs studied previously (skin, kidney and lung), maintains its function in the osmoregulatory process during hibernation.

Ultrastructural changes of neutrophils following IL-2 treatment in vivo

An ultrastructural analysis of peripheral blood cells of cancer patients following recombinant interleukin-2 (rIL-2) treatment at high doses (rIL-2, 18 x 10(6) I.U./m2/day) has been performed. Characteristic patterns of intense phagocytosis (neutrophils with large vaculoes containing electron-dense bodies) were observed in granulocytes of the treated patients with respect to the basal situation. These characteristics were particularly evident in the advanced stages of the therapy (24 and 48 h). The state of neutrophil activation was sometimes accompanied by the appearance of a close net of cell membranes, probably derived from lamellopodia.

Tumor interstitial fluid: misconsidered component of the internal milieu of a solid tumor

The tumor interstitial fluid (TIF) is a fluid phase present in the extracellular space of all tumors whose importance in oncology is seldom recognized. In order to stimulate other researchers to give it the due importance, a review of the available data (including our own) is provided. An hypothesis is presented for the genesis, fate and role of the TIF in the processes of invasion, growth and metastatization. Open questions regarding the TIF's role in tumor response to therapy are raised.

Characterization of the metabolism of perinecrotic cells in solid tumors by enzyme histochemistry

Hypoxic tumor cells resist most therapies and cause tumor regrowth when their environment improves. Identifying the adaptation strategies to hypoxia would help develop better tailored cancer therapies. Ehrlich carcinomas implanted on mice were analyzed histochemically for the following enzyme activities: lactate, succinate and glucose-6-phosphate dehydrogenases, dihydrofolate reductase, purine nucleoside phosphorylase, xanthine oxidoreductase, and acid phosphatase. With the exception of xanthine oxidoreductase, which was not active in tumor cells, and of succinate dehydrogenase the activity of which was not significatively altered, all other activities were much higher in perinecrotic cells with respect to cells close to blood vessels. These data suggest the integration of metabolic paths allowing purine and lipid biosyntheses. Degradation products from the necrosis are presumed to be employed as surrogates of blood-borne nutritive substances by cells distant from the vascularization.

Morphofunctional characterization of lymphokine activated killer (LAK) cells in vitro

In order to characterize the cellular subsets of peripheral blood lymphocytes cultured with interleukin-2 (IL-2), a study in vitro was developed. Both conditioned medium from PHA-stimulated lymphocytes and recombinant IL-2 (rIL-2) were employed. The following aspects were examined: the morphological pattern of IL-2 stimulated lymphocytes; the ability of these cells to recognize, bind, attack and destroy tumoral lines; their cytochemical and immunological (CD) feature. The results suggest that, in our experimental conditions, these cells showed a characteristic "hand mirror shape", cytotoxic antitumor activity, lack of hydrolytic enzymes and CD3+, CD4+ phenotype.

Neuroprotective effects of alpha-dihydroergocryptine against damages in the substantia nigra caused by severe treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine

The effects on the substantia nigra of alpha-dihydroergocryptine (DEK), a drug with strong dopaminomimetic activity, were tested with a severe 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment in monkeys. Compared with monkeys treated with MPTP alone, the animals which received DEK plus MPTP showed reduced neuronal death in the substantia nigra. The reactive astrocytes were increased in number. Moreover, several axons which were immunopositive to phosphorylated neurofilament proteins and with features similar to those of control animals were seen in the pars compacta. The findings suggest that DEK preserves neuronal morphology and brain architecture.

Immunohistochemistry of dihydrofolate reductase in methotrexate-sensitive and -resistant human cell lines by flow cytometry: a comparison with the cytochemical tetrazolium salt method

Dihydrofolate reductase (DHFR, EC 1.5.1.3) is an enzyme involved in the metabolism of nucleic acids; it is also an important target for folate antagonists such as methotrexate (MTX). The distribution and expression of DHFR both in human HeLa BU-25 cell line and in methotrexate-resistant (MTX-R) variant, deriving from the human VA2-B cell line (having the DHFR gene amplified) was studied by tetrazolium salt method and by flow cytometric analysis. The immunohistochemical labelling of DHFR was achieved by using the streptavidinbiotinilated complex technique. DHFR activity was low in the human HeLa BU-25 cell line, while it was very high in the MTX-R cell line; the activity level increased with the increasing concentration of the MTX. The results obtained with cytochemical and immunohistochemical technique were compared. These findings showed that the hyperproduction of DHFR is strictly related with the cells having the DHFR gene amplified. Since MTX resistance is a common finding in the cells of patients with acute leukaemia, these studies may be extended to tumour-bearing patients at onset and following chemotherapy with methotrexate.

Stroma formation in Ehrlich carcinoma. I. Oedema phase. A mitosis burst as an index of physiological reoxygenation?

Tumor stroma induction has been shown closely to resemble wound repair process, both involving the replacement of a fibrin gel by vascularized connective tissue. In such a process the initial phase of hyperpermeability of blood vessels leads to diffuse oedema. It is here reported that cell loosening and a remarkably high mitotic burst were observed in Ehrlich carcinoma in regions in contact with the exudate, particularly at the perinecrotic (hypoxic) region. This suggests both an enhanced cell detachment from the tumour parenchyma and an improvement of the microenvironment, the exudate thus appearing as beneficial to the malignant cells contributing to the reoxygenation of formerly hypoxic regions. The temporary and well-localized concentration of mitoses in inner tumour areas has perhaps been disregarded by the pathologists engaged in mitosis counting for tumour grading. Peripheric and intraparenchymal concentrations of mast cells, lipid pools and platelets were seen in apparently key geometric disposition for controlling fibrin deposition and angiogenesis. Hypoxia is known to cause resistance to oxygen-dependent treatments and to facilitate cell detachment; normal fibroblasts respond and survive under hypoxic conditions by exhibiting features of the malignant phenotype. During reoxygenation, gene instability, cellular heterogeneity and increased drug resistance and metastatic spread have been reported. A reoxygenation process can also be deduced from several other histochemical and morphological patterns observed in this study. The findings here reported thus suggest that the oedema phase is a crucial phase regulating growth, invasion and dissemination of tumour cell populations, that should be specifically addressed therapeutically.

Histochemical probes for the detection of hypoxic tumour cells

Hypoxia is thought to be a major cause of failure in cancer treatment. In this paper, we report methods transposable to clinical practice, for identifying hypoxic tumour cells. They consist of histochemical tests for revealing lactate dehydrogenase activity, endogenous lactate and accumulation of neutral fat. An ascites tumour (Yoshida hepatoma) and a solid tumour (Ehrlich carcinoma) were used as the experimental models. A gel film technique was used for visualizing lactate dehydrogenase and "nothing dehydrogenase" (or endogenous lactate). The fluorescent dyes Nile Red and Acridine Orange were used to demonstrate lipid accumulation and to visualize the tumour morphology, respectively. Tumour cells at the edge of areas of necrosis and at a distance of about 130 microns from a blood vessel were presumed to be hypoxic and showed the following features: 1) a dark blue granular pattern of lactate dehydrogenase (LDH) activity, ascribed to intense activity of the LDH5 and/or LDHk isoenzymes bound to membranous structures; 2) an intense granular positivity of "Nothing Dehydrogenase" due to high concentrations of endogenous lactate; 3) neutral lipid droplets emitting an intense yellow fluorescence in Nile Red-stained preparations; 4) a yellow cytoplasmic fluorescence in Acridine Orange-stained sections, attributable to a low cellular RNA content. Electron microscopy revealed moderately osmiophilic lipid globules in close association with damaged mitochondria. Better oxygenated cells showed: (a) a reddish-blue diffuse pattern of LDH, ascribed to moderately active soluble LDH isoenzymes containing H subunits; (b) almost no "Nothing Dehydrogenase" positivity; (c) no cytoplasmic lipid droplets; and (d) an intense orange-red fluorescence in the cytoplasm of Acridine Orange-stained specimens, due to high concentrations of cellular RNA. Nile Red fluorescence showed that the lipids of the solid tumour membranes were more hydrophobic than in the normal surrounding tissue. This suggests that there are abnormal domains of neutral lipids in the tumour cell membranes. In solid tumours, cells with the characteristics attributable to hypoxia were usually observed on the edge of necrosis of cuff-like formations. In very advanced growth stages, however, they were also seen surrounding (and occasionally clogging) blood vessels, or in tentacular formations coming from a necrosis border and polarized towards the vessels. Lipid-loaded cells were also seen in blood vessels distant from the tumour. These observations point towards a chemotactic process of hypoxic cells towards better environments.

DNA double staining for a fluorescence energy transfer study of chromatin in liver cells

Methodological aspects related to the application of techniques based on fluorescence energy transfer in the study of chromatin structure, were first examined. Fluorochromes specific for DNA with different interaction mechanisms were employed, both in single and double stainings. The following dye pairs were considered as donor/acceptor couples: Hoechst 33342 or DAPI/Mithramycin A or Chromomycin A3, Hoechst 33342 or DAPI/Propidium Iodide, and Mithramycin A or Chromomycin A3/Propidium Iodide. Spectrofluorometric analysis showed that the spectral distribution of the dye pair Ho/PI is more suitable for the evaluation of energy transfer efficiency. This dye pair was used in the study of the chromatin microstructure in rat hepatocytes isolated from livers at two different growth stages. In particular, diploid mono- and binucleated cells from young and adult rats were considered. The results indicated the existence of a more homogeneous situation in young than in adult rats. In the latter case, the statistical analysis indicates the presence of two groups of energy transfer values. The different efficiency values in energy transfer can be considered a consequence of chromatin structure rearrangement and are tentatively interpreted according to the functional role of the diploid cells in the two stages of liver growth.

A qualitative and quantitative cytochemical assay of dihydrofolate reductase in erythroid cells

The distribution and intensity of dihydrofolate reductase (DHFR) cytochemically demonstrable was studied in erythroid cells. Cells of normal human bone marrow, of human erythroleukaemia (M6), and cells of the Friend (MEL) clone 745A murine erythroleukaemia (also after differentiation with dimethylsulphoxide, DMSO) were stained according to Gerzeli and de Piceis Polver (1969) technique; quantification of the reaction product was made using a Vickers M86 microdensitometer. The enzyme activity progressively decreased during the normal differentiation of the erythropoietic series while persisted at high levels in erythroleukaemia cells. It can be suggested that in the 1st case, the cytochemical pattern of dihydrofolate reductase may be a useful added tool for studying the erythroid differentiation. In the 2nd case, the increased level of this enzyme may be related to an amplification of the gene of DHFR in the malignant transformation.

The action of cisplatinum (cis-DDP) on the postnatal growth of the rat liver. Cytokinetics and ultrastructural studies

The early and late effects of cis-DDP treatment on liver cell kinetics were analyzed after its intraperitoneal injection into 17-day old rats. Frequency of binucleate hepatocytes, cellular DNA content distribution, 3H-thymidine labelling and ultrastructure of the nuclei were analyzed. Two days after treatment, a block of mononucleate hepatocytes in the S phase and in the G2 phase was demonstrated by the increase of intermediate 2c-4c and 4c DNA values in the absence of changes in 3H-thymidine labelling; 8c binucleate cells, which are essential for the formation of tetraploid mononucleate cells, were not found. In cell nuclei, large areas of more condensed chromatin appeared, perhaps providing further evidence for a G2 block. Seven days after treatment, there was a tendency to catch up with the normal situation, as shown by the unblocking of the S phase in mononucleate cells indicated by both cytophotometry and autoradiography. The presence of 8c binucleate cells and 4c-8c mononucleate cells indicates that 4c mononucleate hepatocytes are either diploid cells in the G2 phase or true tetraploid G1 cells. The decrease in the heterochromatin areas and the appearance of hypertrophic nucleoli demonstrate an increase in the metabolic activity of the nuclei. Thirty six days after treatment, the incidence of different DNA hepatocyte classes and the 3H-thymidine labelling were already similar in control and in treated rats.

Tetrahydrofolate dehydrogenase cytochemistry in acute lymphoblastic leukemia

We studied the cytochemical distribution of tetrahydrofolate dehydrogenase (FH4D), an enzyme involved in nucleic acid metabolism and thus in cell proliferation and differentiation processes, in bone marrow blasts from 37 cases of acute lymphoblastic leukemia (ALL), of whom 23 were pediatric patients. 26 cases were analyzed at onset, 11 in relapse. The ALL cases were immunologically classified as T (10), common (20), B (3) and null (4). In each subgroup the majority of lymphoblasts were positive, with heterogeneous positivity patterns and variable degrees of enzyme activity. Most T lymphoblasts were characterized by focal localization of FH4D, whereas in common blasts reactivity - usually less strong - was either focally localized or scattered with several fine granules. Finally, many B and null blasts showed diffuse positivity. A quantitative evaluation of FH4D activity using cytophotometric technique (Vickers M86) demonstrated higher degrees of reactivity in leukemic blasts than in normal lymphocytes. Moreover, slightly different levels of reactivity were observed in relation to immunological phenotype, age and stage of the disease. Therefore we think that FH4D is a useful additional marker for ALL characterization.

Dihydrofolate reductase activity in the Purkinje neuron populations of some non-mammalian vertebrates

The intensity and distribution of histochemically demonstrable dihydrofolate reductase (FH2-R EC 1.5.1.3.) in unfixed cryostat sections was studied in Purkinje neurons of adult vertebrates that have either simple neural circuits and cytoarchitectonics (Ictalurus nebulosus, Rana esculenta) or complex neural circuits and cytoarchitectonics (Coturnix coturnix japonica), compared with the rat as a control. The reaction was generally undetectable in Ictalurus nebulosus and in Rana esculenta; with positive reactions in only a few neurons. On the contrary, FH2-R in the Purkinje cell population of Coturnix coturnix japonica had several pattern (heterogeneity) as in the rat. These results suggest that the existence of FH2-R in Purkinje cell population may be correlated with the complexity of the neural circuits of the vertebrate's cerebellum and that the "heterogeneity" of the reaction may be related to the different functional states of the Purkinje cells within the cerebellum.

Qualitative and quantitative study of dihydrofolate reductase in myelodysplastic syndromes

Dihydrofolate reductase (FH2-R) was studied cytochemically in the bone marrow erythroblasts of 20 normal controls and 46 patients with myelodysplastic syndromes (MDSs) classified according to FAB, prior to therapy. The reaction product was quantified for the same samples with a Vickers M86 microdensitometer. The enzyme activity progressively decreased during the normal differentiation of the erythroid cells and persisted at high levels in MDS cells. The high level of FH2-R may be related to the malignant transformation of the cells, or to increased compensatory erythropoietic activity of ineffective erythropoiesis, or to both.

Nuclear changes and morphology of the epidermis in the hibernating frog

Cytochemical changes of chromatin and DNA in frog epidermal cells were correlated with some morphological features to investigate the skin physiology during hibernation in comparison with the active period. The epidermal cells of hibernating frogs showed less condensed chromatin in all the layers; a greater loss of DNA was found during the transition from the middle to the superficial layer. In the germinative layer, a lesser frequency of hyperdiploid cells and a remarkably low amount of mitoses were detected; this is accompanied by the increase of epidermal thickness and the presence of two layers of cornified cells. The slowing of tissue differentiation and cell renewal kinetics during hibernation can be related to lowered activity of the frog skin. Further, the smaller intercellular spaces as well as the scarcity of puffed ER and vacuoles may be indicative of a lower ion transport in epidermal cells during hibernation.

Leucine aminopeptidase activity in blood and hemopoietic organs of different vertebrates. A histochemical comparative study

Leucine aminopeptidase distribution was examined in the cells of peripheral blood and hemopioetic organs of different Vertebrate classes using histoenzymatic methods. Various degrees of staining intensity were observed in leukocytes of the distinct Vertebrates: in particular, leukocytes of fresh water Osteichthyes and Mammals looked strongly positive, whereas leukocytes of Amphibians, Reptiles, and Birds were barely reactive without great differences among species. The observations should be related to enzyme molecular structure and to kinetics and substrate specificity.

Ultrastructural patterns of the alpha-naphthyl butyrate esterase activity in normal and leukaemic peripheral blood leucocytes

The activity of alpha-naphthyl butyrate esterase was investigated at the ultrastructural level in normal human peripheral blood and in a few cases of hairy cell leukaemia, B-chronic lymphocytic leukaemia and acute monocytic leukaemia. A membrane reactivity was detected in most normal monocytes and lymphocytes. The activity in monocytes was very strong and was inhibited by NaF. It was NaF-resistant and less intense in lymphocytes. The reaction product was localized in the cytoplasm only in a small percentage of lymphocytes. In lymphocytes and monoblasts from pathological samples the pattern of reactivity was similar to that found in their normal counterparts, except for a lower intensity. The hairy cells showed a discrete distribution of the NaF-resistant reaction product on their cell surface. The different patterns of enzyme distribution are discussed critically.

Morphohistochemical changes in hepatocytes during the life cycle of the European eel

The comparative analysis of morphological, histochemical and cytochemical patterns of eel (Anguilla anguilla L.) hepatocytes reveals clear differences between two stages of its life cycle, i.e. the trophic stage (yellow eel) and reproductive stage (silver eel). The storage of glycogen prevails in the yellow eel, whilst lipids appear to be remarkably increased in the silver eel, in which some hepatocytes also show glycogen-rich areas. Generally, in the silver eel dehydrogenase and acid phosphatase activities seem greater and different distribution of the reaction products is present; on the contrary, a lower G6PDH activity is observed. The electron microscopy characteristics and distribution of both cellular organelles and reserve materials reflect the modifications found at light microscopy. The ultrastructural patterns provide further evidence for the heterogeneity of liver parenchyma in silver eel. In particular, the coexistence of nuclei showing a different degree of chromatin compactness is also accounted for by the quantitative cytochemical data on the nuclear DNA after Feulgen reaction and intercalation with propidium iodide at low and high concentrations. With regard to the DNA content, the hepatocytes in the silver eel as well as in the yellow eel are mainly 2c. However, some 4c values are also found, which according to the literature can be ascribed to cells in G2 phase. The present data may express the onset of different functional requirements during the reproductive stage in comparison with the trophic one. Moreover, our results are consistent with modifications found by other authors as a consequence of interruption of nourishment and during gonad maturation, i.e. two phenomena characterizing the transition from yellow to silver eel.

Cytochemical study of K+-dependent p-nitrophenyl-phosphatase activity in the urinary bladder of Salamandra salamandra

The ultrastructural Na+-K+-ATPase localization in the salamander urinary bladder has been studied by the histochemical techniques of Ernst (1972) and Mayahara et al. (1980). Reaction products have been specially found on the basal and lateral membranes of granular and mitochondria-rich cells. The variable presence of artifacts, often accompanying Pb-capture phosphatase cytochemistry, is discussed. Additional data on the active ion transport have been obtained by using electrophysiological techniques.

Cytochemical pattern of alpha-mannosidase, alpha-fucosidase and neutral maltase in normal blood cells

The activity of alpha-mannosidase, alpha-fucosidase and neutral maltase was studied by cytochemical techniques in blood cells of 20 controls and of 4 T and B lymphocyte concentrates. All granulocytes, monocytes and platelets showed fine or coarse reaction product deposition, whereas lymphocytes were negative or showed various positivity patterns. A significant difference of the positivity between T and B subpopulations was observed only for the fucosidase reaction. It is possible that the different positivity patterns of the lymphoid cells are related to different functional activities. Further studies will probably confirm the interest of the alpha-fucosidase reaction for the characterization of normal and pathological lymphoid cells.

Comparative aspects of circulating erythrocytes in the trophic and reproductive phases of European eel. Ultrastructure and cytochemistry

Different cytochemical and morphological parameters were used to compare the functional patterns of the erythrocytes in the transition from the trophic (yellow eel) to the reproductive (silver eel) phases of European eel (Anguilla anguilla L.). Data on the nucleus were obtained by microdensitometric (Feulgen reaction) and cytofluoremetric (propidium iodide and Hoechst 33342 fluorochromization) evaluations of DNA staining intensity. In the silver eel, chromatin condensation was more heterogeneous and chromatin also appeared to be looser. The fluorochromes provided information on the different degrees of organization of the chromatin filament, with regard to both primary and higher order DNA structure. In the silver eel, the fine structure showed a higher number of erythrocytes with large euchromatinic areas and the heterochromatinic component was occasionally present in scattered clumps. As for the cytoplasm, in the silver eel a positive correlation could be established between the presence of intact cytoplasmic organelles (mitochondria, Golgi complexes, ribosomes, etc.) and the high fluorescence intensity. This aspect is revealed through the detection of definite membrane components such as glycoconjugates and primary amino groups (PAS reaction and fluorescamine staining, respectively). All these findings allowed us to establish that the transition from the trophic to the premigratory reproductive phase is marked by a higher heterogeneity of the erythrocytes, due to different cell maturation levels. This fact can be ascribed to different metabolic requirements as well as to a more intense erythropoiesis, typical of the most active phase of the eel's life.

Cytochemistry of cell surface sialoglycoconjugates in endometrial adenocarcinoma. Effects of medroxyprogesterone therapy

Ferritin- and rhodamine-conjugated Limulus polyphemus agglutinin was used to localize, by electron microscopy, and to quantify, by microfluorometry, the cell surface sialoglycoconjugates in human endometrial adenocarcinoma before and after medroxyprogesterone acetate therapy. In the untreated tumor the lectin labelling was irregularly distributed on the cell surface, with a maximum density at the apical area and at the intercellular border; high values of the density-binding sites on cell surface were also detected by cytofluorometry. The binding pattern in both electron microscopy and microfluorometry on normal tissue and on tumor tissue submitted to medroxyprogesterone acetate stimulation appeared clearly modified; the lectin labelling concerned the apical areas only (also after treatment with chelating agents), with low fluorometric values of the reactive site density. The differences found in the lectin binding to the cellular sialic acid residues may be due to sialoglycoconjugate quantitative changes and/or to their different reactivity resulting from alterations of the cell membrane architecture. The data appear also correlated with a different proliferative activity and ploidy level of the three situations analyzed.

Cytofluorometric study of the erythrocyte glycoconjugates content in different species of vertebrates

The PAS-positive material was measured by cytofluorometry in peripheral circulating erythrocytes of 22 species from different classes of Vertebrates. The following parameters were considered: total fluorescence intensity per cell, concentration index, fluorescence fading. The highest variability of concentration indexes was found in Fishes with a minimum in the more active swimmers (Scylliorhinus and Salmo); this fact may be related to a more intense erythropoiesis. The values were more homogeneous in the Amphibians, Reptiles, and Birds, the difference never exceeding 1/2 between the maximum and minimum values. The lowest concentration indexes were found in Mammals, a class with very specialized and enucleated erythrocytes: the data appear rather heterogeneous with a minimum in Macaca. The patterns of fluorescence fading suggest a biochemical homogeneity of the PAS-positive erythrocyte material in the species considered. This fact might indicate the presence of a fundamental biochemical component possibly linked to different structures of the red cells.

Propidium iodide as a probe for the study of chromatin thermal denaturation in situ

The possibility of using propidium iodide, a phenanthridinic fluorochrome specific for double-stranded nucleic acids, for the study of chromatin thermal denaturation in situ has been examined. Smears of lymphocytes and hepatocyte nuclei from 15-day-old rats were fixed in acetic acid--ethanol (1:3 v/v), treated with RNAse and submitted to different protein extraction procedures, namely, incubation with pepsin, trypsin and sodium chloride. Denaturation experiments were performed in Sörensen buffer at pH 7.4 containing 10% formamide at temperatures between 27 and 95 degrees C. The samples were stained with propidium iodide and mounted in buffer or glycerol. Measurements were performed with a microfluorometer at a wavelength of 446 nm. The results indicate a higher thermostability of lymphocytes as compared to hepatocytes. The denaturation pattern suggests a certain organization complexity of chromatin, better emphasized by the derivative curves which show the presence of at least three fractions with different melting points. After protein extraction, the denaturation curves exhibit a somewhat simplified pattern, with the disappearance of the most stable peak in the derivative curves. The samples mounted in glycerine exhibit a better stability of staining with time, and an increased quantum efficiency of the fluorochrome with regard to those mounted in buffer. These data confirm the importance of protein--DNA interactions in the organization of chromatin and point to some differences, depending on the cell type and on functional activity.

[Histochemical demonstration of tetrahydrofolate dehydrogenase in human bone marrow: apparent enzymatic induction after administration of folic acid antagonists]

Folate antagonists interfere to a varying extent with the histochemical demonstration of tetrahydrofolate dehydrogenase. Some aspects of this interaction are investigated in normal hemopoietic cells of patients following antitumor treatment with methotrexate. In this situation the histochemically detectable activity of tetrahydrofolate dehydrogenase exceeds the control levels (apparent enzymatic induction). A protection of the enzyme-metabolite complex from degradation and diffusion might be effective for the changes in reaction intensity.

Tetrahydrofolate dehydrogenase in blood cells and in hematopoietic organs of different vertebrate species

Some general aspects in cytochemical demonstration of the tetrahydrofolate dehydrogenase, concerning the final reaction product, are studied. Steady and variable factors are detected in a comparative study of Vertebrate hemopoiesis: the enzyme exhibits peculiar features in different cell types. The reactivity progressively decrease in the erythropoietic series, in concomitance with hemoglobin synthesis. Conversely an increase in the intensity of reaction is found in the granulocytopoietic series; the correspondence of positive material with the specific (eosinophil and heterophil) granulations can be discussed. The thrombocytopoietic series is also labelled by this reaction.

Changes in liver cells ploidy of young rats following isoprenaline treatment

Cell proliferation induced by isoprenaline (IPR) stimulation in very high doses was assayed in the liver of young rats, and the formation of polyploid cells was studied form the 15th to the 70th day of life. A general stimulatory effect on a complex process of cellular multiplication, leading to a population of tetraploid cells, was found to be accelerated; the earlier appearance of binucleate cells and the subsequent significant variations in their incidence confirmed the role of this cell type as an intermediate step in the process of polyploidization. Evidence was found of concomitant size changes of the hepatocytes, which might be partially independent of the effect of DNA content. The stimulation was no longer evident 20--30 days from the end of treatment, by when the cells which had come into contact with IPR should have completed the whole sequence of events leading to the formation of tetraploid mononucleate cells.

The sulfatides and some histochemical correlations of the lachrymal glands involved in salt secretion in Chelonia

High concentrations of sulfolipids (four fractions having different hexose/sulfate ratio), intense enzyme activity (ATPase, oxoreductases) and evidence of mucines (staining with PAS and Alcian blue) in intercellular spaces were found in the lachrymal glands of Caretta caretta and Malaclemys terrapin adapted to sea water. In addition, the supranuclear region of the gland cells in Malaclemys terrapin is filled with mucin granules. These biochemical and histochemical observations indicate that these glands have a function in salt secretion in both species and are also consistent with a function of mucous secretion exclusively in Malaclemys terrapin. Limited signs of hypotrophy are not accompanied by changes in concentrations of sulfolipids in Malaclemys terrapin adapted to fresh water; only the reactions for enzyme activities are less intense. The mucous secretion is not affected, whereas, in correlation with changes in salt secretion, the change in ATPase activity is mot conspicuous. The correlations between the different components of the gland and salt secretion are compared with salt glands of birds and elasmobranchs.