Tracer Technique to Measure in Vivo Chemical Transport Rates within an Implantable Cell Transplantation Device

An in vivo tracer technique that uses radiolabeled inulin as the tracer molecule has been developed to assess the rate of chemical transport between the cell transplantation chamber of an implantable bioartificial device and the host's circulatory system. The device considered here employs site-directed neovascularization of a porous matrix to induce capillary growth adjacent to an immunoisolated cell implantation chamber. This device design is being investigated as a vehicle for therapeutic cell transplantation, with the advantages that it allows the cells to perform their therapeutic function without the danger of immune rejection and it avoids damaging contact of blood flow with artificial surfaces. A pharmacokinetic model of the mass transport between the implantation chamber, the vascularized matrix, and the body has been devised to allow proper analysis and understanding of the experimental tracer results. Experiments performed in this study have been principally directed at evaluation of the tracer model parameters, but results also provide a quantitative measure of the progression of capillary growth into a porous matrix. Measured plasma tracer levels demonstrate that chemical transport rates within the implanted device increase with the progression of matrix vascular ingrowth. Agreement between the fitted model curves and the corresponding measured concentrations at different levels of capillary ingrowth demonstrate that the model provides a realistic representation of the actual capillary-mediated transport phenomena occurring within the device.

Evaluation of an Immunoisolation Membrane Formed by Incorporating a Polyvinyl Alcohol Hydrogel within a Microporous Filter Support

An immunoisolation membrane formed by incorporating a high water content polyvinyl alcohol (PVA) hydrogel into a microporous polyether sulfone (PES) filter has been investigated in this study. The PVA hydrogel is formed in situ within the filter pores via glutaraldehyde (GA) crosslinking under acidic conditions. The tortuous nature of the microporous filter pores securely anchors the embedded hydrogel to provide excellent structural integrity. The high void fraction of the PES filter support (>80%) and high water content of the PVA hydrogel (>85% water by weight) allow excellent solute transport rates, while an appropriate level of glutaraldehyde crosslinking supplies the required molecular size selectivity. In vitro permeability measurements made with solutes covering a wide range of molecular sizes demonstrate high transport rates for small nutrient molecules with rapidly diminishing permeabilities above a molecular weight of approximately 1,000 Dalton. Implantation experiments show that the membrane properties are not deleteriously affected by prolonged in vivo exposure or common sterilization techniques. Thus, this hybrid hydrogel/filter membrane system offers a promising approach to the immunoisolation of implanted cells.

Carcinogen induced unscheduled DNA synthesis in mouse hepatocytes

Mouse primary liver cell cultures were examined for evidence of unscheduled DNA synthesis (UDS) following treatment with the carcinogens; dimethylnitrosamine (DMNA), diethylnitrosamine (DENA), 2-acetylaminofluorene (2-AAF), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), benzo(a)pyrene (BP), dimethylbenzanthracene (DMBA), 1,1,-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), safrole, diethylstilbestrol (DES), aflatoxin B1 (AFB1), and dieldrin and the noncarcinogens; dimethylformamide (DMF), fluorene, and pyrene. Mouse hepatocyte cultures were simultaneously treated with three concentrations of each compound and 3H-thymidine. After 24 hrs, cells were fixed and processed for autoradiography. 3H-thymidine incorporation in both experimental and control cell nuclei, as evidenced by autoradiographic grains, was quantitated microscopically. DMNA, DENA, 2-AAF, MNNG, BP, AFB1 and DMBA significantly increased UDS over untreated cells at all concentrations studied. DDT, DMF, fluorene, pyrene, safrole, DES, and dieldrin were negative for UDS in all concentrations examined. DMNA, 2-AAF and MNNG were also studied for UDS induction in 2 hr old, 1 day old and 4 day old cultures. A progressive decrease in UDS with increased time after plating was found in DMNA and 2-AAF treated cultures. After 4 days DMNA and 2-AAF induced UDS only at the highest concentrations examined (10(-3) M and 10(-4) M respectively). MNNG induced UDS at all time periods and concentrations sampled. An attempt to enhance the sensitivity of the UDS assay by inducing the mixed function oxidative enzyme activity in the hepatocytes with phenobarbital administered in vivo resulted in no statistically significant increase in UDS with DMNA, 2-AAF, MNNG, DDT, and dieldrin when compared with cells from non-induced animals.

Evaluation of an immunoisolation membrane formed by incorporating a polyvinyl alcohol hydrogel within a microporous filter support

An immunoisolation membrane formed by incorporating a high water content polyvinyl alcohol (PVA) hydrogel into a microporous polyether sulfone (PES) filter has been investigated in this study. The PVA hydrogel is formed in situ within the filter pores via glutaraldehyde (GA) crosslinking under acidic conditions. The tortuous nature of the microporous filter pores securely anchors the embedded hydrogel to provide excellent structural integrity. The high void fraction of the PES filter support (>80%) and high water content of the PVA hydrogel (>85% water by weight) allow excellent solute transport rates, while an appropriate level of glutaraldehyde crosslinking supplies the required molecular size selectivity. In vitro permeability measurements made with solutes covering a wide range of molecular sizes demonstrate high transport rates for small nutrient molecules with rapidly diminishing permeabilities above a molecular weight of approximately 1,000 Dalton. Implantation experiments show that the membrane properties are not deleteriously affected by prolonged in vivo exposure or common sterilization techniques. Thus, this hybrid hydrogel/filter membrane system offers a promising approach to the immunoisolation of implanted cells.

High density insulin receptor-positive T lymphocytes from nonobese diabetic mice transfer insulitis and diabetes

In the nonobese diabetic mouse, insulin-dependent diabetes is an autoimmune disease characterized by T cell-mediated invasion and destruction of pancreatic islet beta cells. The importance of insulin receptor (IR) expression in the pathogenesis of diabetes was examined, since it has been shown that the IR is a chemotactic receptor capable of directing cell movement in response to insulin. Using polyclonal antisera to the IR, phenotypic analysis of purified splenic T cells from diabetic mice showed that about 15% of T cells expressed high density IR (IRhigh). In addition, IRhigh T cells were already a dominant phenotype in the insulitis of young prediabetic mice. To determine the ability of IRhigh T cells to transfer diabetes, cells were sorted by flow cytometry before adoptive transfer into young (6- to 8-wk-old) nondiabetic irradiated nonobese mice. Transfer of as few as 3 x 10(6) purified IRhigh T cells alone resulted in rapid onset of insulitis and diabetes, and IRhigh-depleted T cells were essentially unable to passage either insulitis or diabetes. The adoptive transfer of disease was not due to the transfer of activated cells, since removal of IL-2R+ or transferrin R+ cells did not alter diabetes transfer. Therefore, IRhigh T cells are aggressively diabetogenic, suggesting that increased IR expression may provide a mechanism for delivering potentially autoreactive T cells to the islet, regardless of their activation state.

High density insulin receptor-positive T lymphocytes from nonobese diabetic mice transfer insulitis and diabetes

In the nonobese diabetic mouse, insulin-dependent diabetes is an autoimmune disease characterized by T cell-mediated invasion and destruction of pancreatic islet beta cells. The importance of insulin receptor (IR) expression in the pathogenesis of diabetes was examined, since it has been shown that the IR is a chemotactic receptor capable of directing cell movement in response to insulin. Using polyclonal antisera to the IR, phenotypic analysis of purified splenic T cells from diabetic mice showed that about 15% of T cells expressed high density IR (IRhigh). In addition, IRhigh T cells were already a dominant phenotype in the insulitis of young prediabetic mice. To determine the ability of IRhigh T cells to transfer diabetes, cells were sorted by flow cytometry before adoptive transfer into young (6- to 8-wk-old) nondiabetic irradiated nonobese mice. Transfer of as few as 3 x 10(6) purified IRhigh T cells alone resulted in rapid onset of insulitis and diabetes, and IRhigh-depleted T cells were essentially unable to passage either insulitis or diabetes. The adoptive transfer of disease was not due to the transfer of activated cells, since removal of IL-2R+ or transferrin R+ cells did not alter diabetes transfer. Therefore, IRhigh T cells are aggressively diabetogenic, suggesting that increased IR expression may provide a mechanism for delivering potentially autoreactive T cells to the islet, regardless of their activation state.

Detection of genomic alterations in human cervical cancer by two-dimensional gel electrophoresis

Two-dimensional gel electrophoresis was used to comprehensively scan the whole genome of 6 cervical intraepithelial neoplasia (CIN) lesions, 7 cervical squamous cell carcinomas, 1 cervical adenosquamous cell carcinoma, and 2 cervical adenocarcinomas for multiple genetic alterations, such as DNA amplification, chromosome deletion, loss of heterozygosity, and chromosome translocation, as compared with the paired normal tissues. DNA spot analysis of the genomic 2-dimensional gels was performed by a computer color overlay system and by spot recognition software allowing for objective spot comparison and quantitation. Nine spots were found to be amplified in the cervical carcinomas while two amplified spots were detected in the CIN III lesions. Fourteen DNA spots were either reduced in their intensity or absent in cervical carcinomas as compared to their normal paired tissues. Reduction of intensity in 6 spots was observed in the 5 CIN III lesions. These genetic alterations may represent changes in cancer genes that are associated with human cervical carcinogenesis. Further characterization of these alterations may be significant to the understanding of cervical tumorigenesis and to the development of biomarkers for clinical trials in cancer chemoprevention.

DNA quantification in cervical intraepithelial neoplasia thick tissue sections by confocal laser scanning microscopy

Image analysis of tissue biopsies for determination of DNA content as an early marker of neoplasia is hampered by the complexity of corrections necessary to dea with nuclear truncation and overlap in thin sections. The use of confocal laser scanning microscopy (CLSM) for measurement of cellular DNA content on whole cells within thick tissue sections offers the advantage of preservation of cellular architecture, capacity for 3-dimensional analysis, and absence of sectioning artifacts. We have applied this technique to pararosaniline-Feulgen stained human cervical tissues graded from normal to cervical intraepithelial neoplasia (CIN) III. For the purpose of comparison, 15 microns sections were stained and mapped so that the same cell population could be analyzed by both integrated optical density and fluorescence intensity. Distribution of DNA content from normal cervical epithelial cells 2-3 layers out from the basal cell layer measured by both methodologies showed a stable G0/G1 population with no observable S-phase or G2 cells. Cells measured from areas of increasing CIN grade showed progressively higher DNA content values that were not observable in normal tissue. Although these data are preliminary they suggest that CLSM can be used to identify aneuploid states within defined structural areas of pre-invasive neoplasia.

Tracer technique to measure in vivo chemical transport rates within an implantable cell transplantation device

An in vivo tracer technique that uses radiolabeled insulin as the tracer molecule has been developed to assess the rate of chemical transport between the cell transplantation chamber of an implantable bioartificial device and the host's circulatory system. The device considered here employs site-directed neovascularization of a porous matrix to induce capillary growth adjacent to an immunoisolated cell implantation chamber. This device design is being investigated as a vehicle for therapeutic cell transplantation, with the advantages that it allows the cells to perform their therapeutic function without the danger of immune rejection and it avoids damaging contact of blood flow with artificial surfaces. A pharmacokinetic model of the mass transport between the implantation chamber, the vascularized matrix, and the body has been devised to allow proper analysis and understanding of the experimental tracer results. Experiments performed in this study have been principally directed at evaluation of the tracer model parameters, but results also provide a quantitative measure of the progression of capillary growth into a porous matrix. Measured plasma tracer levels demonstrate that chemical transport rates within the implanted device increase with the progression of matrix vascular ingrowth. Agreement between the fitted model curves and the corresponding measured concentrations at different levels of capillary ingrowth demonstrate that the model provides a realistic representation of the actual capillary-mediated transport phenomena occurring within the device.

Photodynamic therapy: a new modality for the treatment of cancer

Photodynamic therapy is a promising new modality for the treatment of neoplastic disease. Currently, Photofrin is the only photosensitizer approved for the treatment of human cancers. In the search for new, chemically pure second generation photosensitizing agents which absorb in the deep red region of the visible spectrum, a novel and unique photosensitizer, CDS1, an iminium salt of copper octaethylbenzochlorin, was developed. This new photosensitizer is chemically pure, cationic, and possesses a strong (epsilon = 35000 M-1.cm-1) absorption peak at 750 nm (in dichloromethane). With copper in the aromatic cavity and a triplet lifetime which is not measurable (< 20 nsec), the photodynamic activity of CDS1 was unexpected. Preliminary in vitro and in vivo animal studies with a transplantable urothelial tumor indicate that CDS1 is an effective photosensitizing agent when used in conjunction with a broad band xenon arc light source or a low frequency, high peak power pulsed alexandrite laser.

Expression and localization of elements of the plasminogen activation system in benign breast disease and breast cancers

The malignant potential of solid tumors is related to the ability to invade adjacent tissue and to metastasize. These properties of cancer cells depend on the synthesis of proteolytic enzymes which are able to digest adjacent connective tissue and basement membranes. We hypothesized that all elements of the plasminogen activation system might be overexpressed in malignant human breast tumors, functioning as an essential element in tumor invasion and metastasis. As determined by histopathological methods, the malignant tumors showed statistically significantly higher expression of urokinase plasminogen activator (uPA), type-1 plasminogen activator inhibitor (PAI-1), and especially urokinase plasminogen activator receptor (uPAR) than benign tissues. All those elements were present in higher amounts in the cancer cells than in the cells of benign or normal breast tissues. High exhibition of tissue plasminogen activator (tPA) found in cancer seems to be random and not related to the malignant or benign state, since benign and malignant tumors show overexpression of tissue plasminogen activator with similar frequency. When the tumors express high amounts of uPA, they express a high amount of uPAR in 50% of cases and PAI-1 in 57.3% of cases. When urokinase is expressed in low amount, the receptor is low in 28.6% and inhibitor in 21.4% of malignant breast tumors. This statistically significant consensus, 78.6% in the case of urokinase and its receptor and 78.6% in case of urokinase and its inhibitor, suggests that these activities may be the result of a unique mechanism of control, activated in the last steps of malignant transformation.

Keratin expression in chemically induced mouse lung adenomas

Chemically induced mouse lung tumors exhibit distinctive growth patterns, characterized by an alveolar or solid appearance, a papillary appearance, or a combination of the two. Lung tumors induced in strain A/J mice by either benzo(a)pyrene (BP) or by N-nitrosoethylurea (ENU) were examined for expression of low- and high-molecular-weight cytokeratins. Simple cytokeratins (low molecular weight) were found in all epithelial cells of the normal mouse lung and in all tumor types, whereas higher-molecular-weight cytokeratins were found only in normal bronchiolar cells and in papillary tumor cells. These data lend support to the hypothesis that chemically induced papillary lung tumors in strain A/J mice are derived from bronchiolar Clara cells.

Glyceraldehyde-3-phosphate dehydrogenase and other enzymatic activity in normal mouse lung and in lung tumors

The histogenesis of chemically induced mouse lung adenomas is currently being debated. Tumors induced by a variety of chemicals and in a number of different strains exhibit growth patterns having a solid/alveolar appearance, a papillary appearance, or a mixture of both. Ultrastructural observations suggest that solid tumors are derived from the alveolar type II pneumocyte and that papillary tumors arise from the bronchiolar Clara cell. However, recent immunocytochemical investigations have concluded that most mouse lung tumors are derived solely from the alveolar type II cell. Enzyme histochemical methods have previously been utilized to identify Clara cells in pulmonary cell isolates and also to characterize mouse lung tumors. This report demonstrates a difference in glyceraldehyde-3-phosphate dehydrogenase (G3PD) activity in type II pneumocytes and Clara cells. Solid tumors and type II cells appear to have a similar G3PD activity, and this activity is different from that observed in papillary tumors and bronchiolar cells. These findings support morphological evidence that suggests mouse lung tumors are phenotypically different and may arise from at least two different cells of origin.

Strain A/J mouse lung adenoma growth patterns vary when induced by different carcinogens

The histogenesis of mouse lung adenomas is currently being investigated in several laboratories. Based upon studies of a limited number of carcinogens in different mouse strains, some investigators suggest that all lung adenomas in mice are derived from alveolar type II cells, whereas others suggest a Clara cell origin for a majority of the tumors. This report differs from previous investigations in that 12 different carcinogens were evaluated for the types of lung tumor growth patterns they induced in a single mouse strain (strain A mice). The carcinogens aflatoxin B1 (AFB1), benzo(a)pyrene (BP), 1,2-dimethylhydrazine (DMH), 3-methylcholanthrene (MCA), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and N-nitrosomethylurea (MNU) induced tumors with a predominantly solid/alveolar growth pattern, whereas N-nitrosodiethylamine (NDEA) induced predominantly papillary tumors. Most of the other carcinogens induced a higher proportion of lung tumors with the solid/alveolar growth pattern than with the papillary growth pattern; however, ratios between the 2 growth patterns varied. If, as suggested by others, solid tumors are derived from alveolar type II cells and papillary tumors from Clara cells, then carcinogens may differ with respect to their ability to transform one cell type or the other.

Metabolic studies of carnitine in a child with propionic acidemia

Carnitine metabolism was studied in a 7-y-old boy with propionic acidemia due to an almost total deficiency of propionyl-CoA carboxylase. The initial diagnosis was made at 3 wk of age followed by numerous episodes of metabolic acidosis despite a low-content branch-chain amino acid diet containing supplemental biotin. Although clinically stable and in a nonacidotic state, the plasma concentration of total carnitine was normal (38.9 microM; normal = 46 +/- 10, mean +/- SD, n = 30) whereas free carnitine was decreased (5.7 microM; normal = 37 +/- 8) and short-chain acylcarnitines were increased (28.6 microM; normal = 5.7 +/- 3.5). Skeletal muscle and liver specimens obtained at open biopsy had low total and free carnitine contents and increased ratio of short-chain acylcarnitines to free carnitine. Short-chain acylcarnitine content was low in liver but increased in skeletal muscle. The liver contained fatty vacuoles, enlarged mitochondria with paracrystalline inclusions, and numerous peroxisomes whereas the skeletal muscle also had lipid vacuoles and an increase in number and size of mitochondria. A carnitine challenge test (100 mg L-carnitine/kg body wt via a gastrostomy tube) resulted in a peak plasma carnitine concentration at 120 min. With maintenance therapy of 100 mg L-carnitine/kg/day the plasma free carnitine remained relatively low, the plasma glycine concentration decreased, and urinary acylcarnitine excretion increased. This study demonstrates that the alterations in carnitine and its derivatives observed in plasma and urine reflect the same type of altered distribution in tissue and provides further data on the effects of L-carnitine therapy.

Relationship between in utero development of the mouse liver and tumor development following transplacental exposure to ethylnitrosourea

Pregnant C3HeB/FeJ mice were treated with ethylnitrosourea (ENU) on one of gestation Days 10, 13, or 15 to determine if ENU treatment at different stages of gestation would result in morphological or quantitative differences in liver tumors induced in the offspring. Liver tumors were counted and measured 6 mo after treatment with ENU. Foci of cellular alteration were identified histologically and counted. Liver tumor number and foci of cellular alteration increased as a function of increasing dose and age at the time of ENU treatment. An inverse relationship between age at the time of treatment and the size of liver tumors was found. The mean tumor volume of male mice exposed on Day 10 of gestation was 123-fold larger than for spontaneous tumors observed in controls. The differences between mean liver tumor volume in mice which had been exposed to ENU on Days 10, 13, or 15 of gestation appeared to be associated with the exponential growth of the fetus during this period of gestation. Unique, large, multinodular foci of cellular alteration were found in mice treated on Day 10 of gestation. The relationship between the stage of gestation and the size of chemically induced liver tumors in these mice is similar to previous observations with transplacentally induced lung tumors in C3HeB/FeJ mice. This indicates that developmentally regulated cell proliferation occurring at the time of carcinogen exposure may affect the subsequent extent of tumor development in both the liver and lung. Therefore, cells transformed during early development may result in tumors that pose a greater biological hazard than those transformed in later development.

Morphometric evaluation of the renal arterial system of Dahl salt-sensitive and salt-resistant rats on a high salt diet. II. Interlobular arteries and intralobular arterioles

The progression of small vessel renal vascular disease was studied in inbred Dahl salt-sensitive (SS/Jr) and salt-resistant rats with acute hypertension induced by a high salt diet. Corrected cross-sectional areas of wall (WAC) and lumen were measured by planimetry and histologic staining for fibrin, hyalin deposition, and elastic lamellae was performed. In SS/Jr rats on the high salt diet, the hallmarks of malignant hypertension (fibrinoid necrosis, hyperplastic and necrotizing arteritis) appeared by week 2 and were intensified after 4 weeks on the high salt diet. Renal vascular lesions from SS/Jr rats were characterized by: hyperplasia and/or hypertrophy of medial smooth muscle cells; intimal proliferation; fibrin, basophilic mucoid, and hyalin deposition within the the subendothelial space and media; variable adventitial fibrosis; and accumulation of mononuclear inflammatory cells in the adventitia and media. Interlobular arteries from both rat strains exhibited significantly increased cross-sectional areas over time for all measured parameters. Intralobular arterioles from both rat strains exhibited significantly increased cross-sectional areas over time for all measured parameters except lumen from SS/Jr rats. For SS/Jr rats, increased WAC from both arterial divisions correlated positively with systolic blood pressure, but not body weight. In salt-resistant rats, increased WAC from both arterial divisions correlated positively with body weight, but not systolic blood pressure. We concluded that the rapid increase in WAC from SS/Jr rats could not be attributed solely to the normal growth of the rat. With the development of acute hypertension in the SS/Jr rat, these results demonstrate the potential usefulness of this model to investigate the pathogenesis of similar renal vascular alterations which are observed in man.

Functional units in rainbow trout (Salmo gairdneri, Richardson) liver: II. The biliary system

The intrahepatic biliary system was studied in the rainbow trout (Salmo gairdneri), a teleost known to form liver neoplasms after exposure to various carcinogens. Normal adults (N = 25) were examined using light microscopic, enzyme histochemical, and transmission and scanning electron microscopic methods. In light micrographs, longitudinal arrays of hepatocytes appeared as double rows incompletely divided by elongated darkly stained cells. Electron micrographs showed tubules of five to nine pyramidally shaped hepatocytes with their apices directed toward a central biliary passageway and their bases directed toward sinusoids. Sequentially, beginning with hepatocytes, biliary passageways included canaliculi, preductules, ductules, and ducts. Canaliculi were short and joined transitional passageways (preductules) formed by junctional complexes between plasma membranes of hepatocytes and small, electron-dense cells with a high nuclear to cytoplasmic ratio. Ductules, completely lined by biliary epithelial cells, occupied central regions of hepatic tubules. Relatively elongated, ductular cells were intimately associated with surrounding hepatocytes, separated from them by only a thin extracellular space devoid of a basal lamina. Epithelium of bile ducts included cuboidal through mucus-laden columnar cells, surrounded by basal lamina and, in larger ducts, by fibroblasts, smooth muscle cells, and a capillary plexus. Bile ducts and hepatic arterioles, but not venules, were distributed together. The ultrastructure of biliary epithelium, periductular, and periductal cells is presented.

Effect of gestational development of lung tumor size and morphology in the mouse

Pregnant C3HeB/FeJ mice were treated with ethylnitrosourea (ENU) on one of gestation Days 10, 13, or 15 to determine if ENU treatment at different stages of gestation would result in qualitative or quantitative differences in lung tumors induced in the offspring. Lung tumors were counted and measured 6 mo after treatment with ENU. Offspring of mice treated with ENU on Day 10 of gestation had a small increase in lung tumors while those treated on gestation Day 13 or 15 had significantly more tumors than controls and 6- to 8-fold more tumors than the treated mothers. An inverse relationship between age at the time of treatment and lung tumor size was found. The mean lung tumor volume of mice exposed on Day 10 of gestation was 167-fold larger than that of mice exposed to ENU as adults. The difference between mean lung tumor volume in mice which had been exposed to ENU on Day 10, 13, or 15 of gestation appeared to be associated with the exponential growth of the fetus during this period of gestation. Lung tumors induced on Days 10 and 13 of gestation were irregular in contour and were multinodular. Sixty-five to 85% of the lung tumors in offspring treated during gestation versus 20% in mice treated as adults had a papillary morphology. These differences in tumor size and morphology indicate that cells transformed during early development may pose a greater biological hazard than cells transformed in older animals.

Morphometric evaluation of the renal arterial system of Dahl salt-sensitive and salt-resistant rats on a high salt diet. I. Interlobar and arcuate arteries

Structural changes in intrarenal arteries of inbred Dahl salt-sensitive and salt-resistant rats with acute hypertension were studied morphometrically. After a week on a normal salt diet (1% NaCl), animals were placed on a high salt diet (8% NaCl) for 4 weeks. Systolic blood pressure (BP) and body weights (BW) were recorded, and six salt-sensitive and six salt-resistant animals were sacrificed weekly for a total of five sampling periods. Corrected cross-sectional (C/S) areas of adventitia, media (MAC), intima, wall (WAC), and lumen (LAC) were measured by planimetry. Although significant increases (p less than 0.01) in both BW and systolic BP were observed over time in both strains, salt-sensitive rats became hypertensive (systolic BP greater than 150 mm Hg) by week 2 on a high salt diet, while salt-resistant rats remained normotensive. In interlobar arteries, significant increases over time were observed for the WAC, MAC, and LAC in salt-resistant rats and in the WAC, adventitia, MAC, and LAC for salt-sensitive rats. Significant increases over time were observed for the WAC, adventitia, MAC, and LAC in arcuate arteries from salt-sensitive rats only. Increased C/S areas observed over time in both strains were observed by week 3 on the high salt diet, after the elevated systolic BP. Analysis of covariance indicated that increased C/S areas observed over time in salt-sensitive rats paralleled elevated systolic BP but did not follow an increase in BW. On the other hand, in salt-resistant rats, increased C/S areas observed over time correlated with BW but not systolic BP. The documented rapid development of vascular changes in salt-sensitive rats in conjunction with the development of acute hypertension demonstrates the potential usefulness of this model for investigating the pathogenesis of hypertensive renal vascular alterations.

Resident sinusoidal macrophages in the liver of the brown bullhead (Ictalurus nebulosus): an ultrastructural, functional and cytochemical study

Ultrastructural, functional, and cytochemical characteristics of resident sinusoidal macrophages (RSM) in brown bullhead (Ictalurus nebulosus) liver were examined. Following perfusion fixation of the hepatic vascular bed, light micrographs revealed RSM that possessed multiple elongate cytoplasmic processes and frequently contained erythrocytes in various stages of degradation. Following brief perfusion fixation, light microscope examination of vibratome sections of bullhead liver reacted for peroxidase revealed intensely positive RSM. By transmission electron microscopy, peroxidase activity was localized to the nuclear envelope and cytoplasmic granules of RSM and in endothelial and perisinusoidal fat-storing cells. In cryostat sections of fresh-frozen liver, glucose-6-phosphate dehydrogenase (G-6-PDH) was uniformly distributed over hepatocytes, whereas intensely positive punctate staining for G-6-PDH was localized over RSM. To test for phagocytosis by RSM, latex beads (0.81 micron) were injected into a tributary of the hepatic portal vein 2 min prior to perfusion fixation. Latex beads appeared either singly or in dense aggregates within RSM. Ultrastructurally, RSM were characterized by an irregularly shaped, eccentrically located nucleus, electron-dense vacuoles, small patches of granular endoplasmic reticulum, a well-developed Golgi apparatus, elongated mitochondria, desmosomes or desmosome-like densities that served as a source of attachment to endothelial cells, and a centriole with radiating microtubules. Invaginations of the plasma membrane (vermiform processes) characteristic of mammalian Kupffer cells were not observed in bullhead RSM. The results indicated a resident cell population of sinusoidal macrophages in the bullhead liver with properties that partially resembled mammalian Kupffer cells. These results are important for the identification of the normal resident cells in the bullhead liver.

Morphologic and histochemical analysis of the newt (Notophthalmus viridescens) liver

Architectural arrangement, ultrastructure, and selected histochemical properties of the newt (Notophthalmus viridescens) liver were examined. Although hematopoietic tissue (1-4 cells thick) invested the liver, direct vascular communication between this tissue and hepatic parenchyma was not observed. The liver was intensely positive when stained with Oil-red-O and periodic acid-Schiff reagent and connective tissue was limited to large vascular channels and the capsule. A distinctive polarity was observed in the hepatic vascular system when lobes were viewed in cross section. Dorsally, portal venules accompanied arterioles and branches of the biliary system, while tributaries of hepatic veins were observed ventrally. Following perfusion fixation, hepatocytes appeared as sheets of cells 1-5 cells thick; however, lobules as defined in adult mammalian liver were absent. Hepatocytes contained abundant smooth endoplasmic reticulum, mitochondria, electron-dense lysosomes, patches of granular endoplasmic reticulum, and lipid droplets. Continuous endothelial cells lined sinusoids and exhibited fenestrae organized into structures similar to sieve plates observed in mammalian liver. Variable numbers of melanin-containing macrophages and subendothelial macrophages were observed; however, Kupffer cells and lipid containing perisinusoidal fat-storing cells were not seen. Patterns of reaction product for glucose-6-phosphatase (G-6-Pase), glucose-6-phosphate dehydrogenase (G-6-PDH), and succinic dehydrogenase (SDH) were localized in the newt liver. All enzymes exhibited a uniform distribution pattern; however, small punctate regions of intensely positive G-6-PDH cells were noted within hepatic parenchyma. Cells comprising the hematopoietic tissue were intensely positive for G-6-Pase, G-6-PHD, and negative for SDH.

Ethylnitrosourea-induced transplacental carcinogenesis in the mouse: tumor response, DNA binding, and adduct formation

We have confirmed previous results which suggest that transplacental exposure of fetal mice to carcinogens does not cause an increase in tumor incidence as they mature unless treatment occurs after midorganogenesis. In C3HeB/FeJ mice we found a negligible increase in tumor incidence and multiplicity following transplacental exposure to the direct-acting carcinogen ethylnitrosourea (ENU) on gestation day 10, but significant increases in lung and liver tumor incidence following exposure on days 13 or 15 or in adults. To explore the possibility that this observed difference is due to differences in the biodistribution of the carcinogen or its interaction with cellular macromolecules, the level of covalent binding between ENU and fetal and maternal DNA following an i.p. injection of a dose of 50 mg/kg of tritium-labeled ENU was measured 30 min after its injection into pregnant females on days 10, 13, and 15 of gestation. The DNA from fetal and maternal lung, liver, and brain was isolated and the amount of covalent binding estimated from the dpm/mg DNA recovered. Samples of DNA were hydrolyzed and chromatographed to determine that the bound tritium was associated with ENU-DNA adducts and not as a product of DNA synthesis. The level of binding of ENU to fetal DNA was equivalent at all gestation days studied but was significantly less than maternal tissues. Binding to the DNA of maternal liver was 4-fold greater than to fetal DNA while maternal lung and brain DNA were bound at intermediate levels. We conclude that the lack of carcinogenic response to ENU documented here, in fetal mice exposed early in gestation (day 10), is not due to differences in ENU binding to fetal DNA during development.

How computers are used in pathology education

How are computers being used to teach pathology? Of 129 major medical teaching institutions surveyed, 63 institutions responded and 37 were using computers in pathology education. Applications include examination, instruction and consultation, case simulation, and course evaluation.

Mechanisms of chloroform and carbon tetrachloride toxicity in primary cultured mouse hepatocytes

Mechanisms of chloroform (CHCl3) and carbon tetrachloride (CCl4) toxicity to primary cultured male B6C3F1 mouse hepatocytes were investigated. The cytotoxicity of both CHCl3 and CCl4 was dose- and duration-dependent. Maximal hepatocyte toxicity, as determined by lactate dehydrogenase leakage into the culture medium, occurred with the highest concentrations of CHCl3 (5 mM) and CCl4 (2.5 mM) used and with the longest duration of treatment (20 hr). CCl4 was approximately 16 times more toxic than CHCl3 to the hepatocytes. The toxicity of these compounds was decreased by adding the mixed function oxidase system (MFOS) inhibitor, SKF-525A (25 microM) to the cultures. The addition of diethyl maleate (0.25 mM), which depletes intracellular glutathione (GSH)-potentiated CHCl3 and CCl4 toxicity. The toxicity of CHCl3 and CCl4 could also be decreased by adding the antioxidants N,N'-diphenyl-p-phenylenediamine (DPPD) (25 microM), alpha-tocopherol acetate (Vitamin E) (0.1 mM), or superoxide dismutase (SOD) (100 U/mL) to the cultures. These results suggest that: in mouse hepatocytes, both CHCl3 and CCl4 are metabolized to toxic components by the MFOS; GSH plays a role in detoxifying those metabolites; free radicals are produced during the metabolism of CHCl3 and CCl4; and free radicals may be important mediators of the toxicity of these two halomethanes.

Histological study of the effect of hematoporphyrin derivative photodynamic therapy on the rat jejunum

Hematoporphyrin derivative photodynamic therapy is evolving as a local treatment for neoplastic disease. The emphasis of previous research has been on the determination of mechanisms of tumoricidal activity and defining the tumoricidal porphyrin component in hematoporphyrin derivative. The effect of hematoporphyrin derivative photodynamic therapy on normal tissue has received little attention. In the following study we examined the morphological changes of normal rat intestine exposed to hematoporphyrin derivative and light. In this model a segment of rat jejunum was exposed to red light (greater than 590 nm; 360 J/cm2) 24 or 72 h after the i.v. administration of hematoporphyrin derivative (5 or 10 micrograms/g body weight). Control groups received either no treatment, hematoporphyrin derivative only, or light only. Four h after treatment, intestinal segments were removed and examined by light microscopy. Segments treated with hematoporphyrin derivative and light showed extensive sloughing of the mucosa and submucosa with sparing of the muscular and serosal layers. It appears that hematoporphyrin derivative photodynamic therapy is capable of causing mucosal and submucosal damage to normal rat jejunum at these doses of light and hematoporphyrin derivative.

Tumor-localizing and photosensitizing properties of hematoporphyrin derivative in hamster buccal pouch carcinoma

The tumor-localizing and photochemotherapeutic properties of hematoporphyrin derivative (HPD) were examined in 7, 12 dimethylbenzanthracene (DMBA)-induced oral cancers in the Syrian hamster. Oral tumors in hamsters injected with HPD (50 micrograms per gram of body weight) exhibited bright salmon pink fluorescence when exposed to long-wave ultraviolet light 24 hours after intraperitoneal HPD injection. Adjacent tumor-free mucosa did not fluoresce. Similarly, tumors not treated with HPD, normal mucosa treated with HPD, and normal mucosa not treated with HPD did not fluoresce. Tumors in animals that received HPD and photochemotherapy (PCT) were examined for gross and microscopic pathologic changes following the phototreatment. Tumors displayed edema, hemorrhage, and cellular necrosis that progressed with the time of sampling after photochemotherapy. Complete tumor necrosis was evident in the majority of oral tumors 24 hours after HPD PCT.

Cellular effects of hematoporphyrin derivative photodynamic therapy on normal and neoplastic rat bladder cells

HPD is known to localize in neoplastic cells and when exposed to the appropriate wavelength of light causes cytotoxicity. The authors have established a rat urothelial cell model for use in comparing and contrasting the effects of HPD photodynamic therapy (PDT) in normal (RBL-01) and transitional cell carcinoma (AY27) bladder cell lines. Uptake, toxicity, and morphologic damage following exposure to HPD PDT were evaluated. Trypan blue exclusion was used for determination of the toxicity of several HPD concentrations (1, 10, 25, and 50 micrograms/ml) with increasing duration of incubation with HPD (0, 1, 2, 4, 12, 24, and 48 hours). Both cell lines displayed increased toxicity with higher concentrations of HPD; however, the AY27 cells were more susceptible to the toxic effects of HPD PDT than the RBL-01 cells at the higher HPD doses studied (25 and 50 micrograms/ml). Viability decreased with increased duration of HPD incubation in RBL-01 cells up until 4 hours, after which it showed a steady increase. Viability decreased in the AY27 cells with increased duration of HPD incubation. An increase in serum concentration in the medium resulted in an increase in viability for both cell lines. Both cell lines demonstrated fast initial uptake of HPD followed by slower uptake over the time studied. By 24 and 48 hours the AY27 cells contained twice the amount of methanol-extractable porphyrins as the RBL-01 cells. The initial morphologic change following HPD PDT was damage to mitochondria. Mitochondrial damage occurred immediately after PDT in the AY27 cells and 30 minutes after PDT in the RBL-01 cells. Both cell lines exhibited a similar progression of cell injury; however, morphologic damage was observed earlier after PDT and appeared more extensive in the AY27 cells.

Jejunal blood flow after exposure to light in rats injected with hematoporphyrin derivative

Experiments were performed to determine the effect of hematoporphyrin derivative (HPD) photodynamic therapy on blood flow to normal rat intestine. A segment of rat jejunum was exposed to red (greater than 590 nm) light (200 mW/cm2) 24 h after the i.v. administration of HPD. Blood flow to the light exposed segment was determined using the radioactive microsphere technique while blood flow to an adjacent light shielded segment of intestine served as an internal control. Animals were divided into six groups of six each: Group I, no HPD, no light; Group II, light, no HPD; Group III, HPD (20 micrograms/g body weight), no light; and Group IV, HPD (20 micrograms/g body weight), light. Blood flow in these four groups was determined 10 min after completion of a 30-min exposure to light. Only in Group IV was there a statistically significant decrease (P less than 0.005) in blood flow to the segment treated with HPD and light. In Groups V [HPD (20 micrograms/g body weight), light] and VI [HPD (10 micrograms/g body weight), light] blood flows were determined 24 h after exposure to light. In both of these groups there was also a significant (P less than 0.05) decrease in blood flow in the segment treated with HPD and light. This study demonstrates that normal intestinal blood flow can be disrupted by HPD photodynamic therapy.

Ultrastructure of the interstitial cells of Leydig, stimulated and unstimulated

The interstitial cells of Leydig which lie in small groups or individually between the seminiferous tubules of the testes, or at the hilum in the ovary, are known to be active in production of androgenic substances, as well as being sensitive to the influence of various trophic hormones. Among the hormones known to be produced by these cells are testosterone, dihydrotestosterone, and estradiol. Responsiveness of the function of the Leydig cells has been demonstrated with luteinizing hormone (LH), growth hormone, follicle stimulating hormone (FSH), and probably estrogen as well as prolactin. Human chorionic gonadotrophin also may have a marked effect. Attempts to correlate the cytologic appearance of Leydig cells with various states of stimulation have revealed a number of ultrastructural appearances. Since a spectrum of cellular morphology is apparent, both in the normal and in altered physiologic states, it is hazardous to ascribe a particular ultrastructural variation to the influence of a given hormonal stimulus. Nevertheless, in normal males, three types of cells can frequently be seen: fusiform cells with ovoid nuclei, small aggregates of smooth endoplasmic reticulum (SER), and variable amounts of cytoplasmic filaments, probably representing resting cells, since they are most abundant in pre-pubertal males; light cells, the most frequent type, with well developed SER, scant rough endoplasmic reticulum (RER), and mitochondria which vary in size and shape, contain abundant lipid and frequent lipochrome deposits; and dark interstitial cells which are variable in number, derive their density from stacks of tubular SER, and may represent merely an altered response to fixation or an involutional form. In addition to immature cells and normal mature cells, two additional cell types are described in various primary testicular disorders: abnormally differentiated Leydig cells with features such as grouped mitochondria, whorls of endoplasmic reticulum, absent or fragmented Reinke's crystals and paracrystalline arrays and deficiency of lipid droplets as well as masses of microfilaments; and a multivacuolated cell type characterized by swelling of cytoplasmic organelles and absence of Reinke's crystals or paracrystalline arrays. It is also clear that the interstitial cells respond in systemic diseases, are injured by alcohol ingestion, and show involutional changes in aging. While these ultrastructural changes are now well documented, there is still a need to correlate them exactly with the various stimuli which may affect testicular function.

Localization of hematoporphyrin derivative in injured bladder mucosa. An experimental study

Hematoporphyrin derivative, a fluorescent mixture of porphyrins, has the putative property of being retained in neoplastic tissue after systemic administration. This preferential retention is the basis for the use of this agent as a tumor localizer and tumor photosensitizer. The retention of hematoporphyrin derivative in non-neoplastic but regenerating urothelium has not been reported. In this study, thermal urothelial injury was induced in Fischer 344 rats. Animals were then injected intravenously with hematoporphyrin derivative at 3 days, 1, 2, 3 and 6 weeks after injury. Photography under ultraviolet illumination was used to detect porphyrin fluorescence in the bladder mucosa. Up to 3 weeks after injury porphyrin fluorescence was detectable in areas of inflammation and hyperplasia around the area of injury. This study suggests that in this experimental model HpD fluorescence is not specific for neoplasia.

Morphologic studies of bladder tumors treated with hematoporphyrin derivative photochemotherapy

The morphologic changes that occurred in transplanted rat bladder tumors after treatment with hematoporphyrin derivative (HPD) and/or phototherapy were investigated. Transitional cell bladder tumors were initiated subcutaneously in male F344 rats by injection of AY27 cells. When tumors reached 1 cm in diameter, the rats received either HPD (10 mg/kg body weight) photochemotherapy, HPD only, phototherapy only, or no treatment. Tumors were sampled immediately (0 time), 1/2, 1, 2, 4, and 24 hours after phototreatment for light and electron microscopy. Tumors receiving HPD-photochemotherapy displayed progressive injury to both tumor cells and endothelial cells. Early changes (0-2 hours) included focal tumor and endothelial cell vacuolation and swelling as well as sloughing of tumor cells into papillary spaces. Tumor cells and endothelial cells displayed vacuolization and damage to cell mitochondria immediately after phototreatment. Intercellular spaces also increased in size. Lethally injured cells were apparent in papillary spaces. At 4 hours after phototherapy, tumor cells and endothelial cells exhibited extensive cell damage, including mitochondrial destruction, endoplasmic reticulum swelling, polyribosome disaggregation, and plasma membrane blebbing. By 24 hours after phototherapy, the majority of cells within the tumor were necrotic. Untreated tumors and those treated with phototherapy-only did not exhibit these changes. Tumors that received HPD only exhibited focal areas of cell swelling and focal mitochondrial vacuolization in both tumor and endothelial cells. These changes, unlike the HPD-light-treated group did not progress and were reversible.

Trout hepatocyte culture: isolation and primary culture

Rainbow trout (Salmo gairdneri) hepatocytes were isolated using a two-step perfusion through the portal vein. A typical perfusion yielded 2.92 X 10(6) liver cells with a mean viability of 96.3%. Hepatocytes comprised 93.4% of the total cell isolate. Survival of hepatocytes in suspension culture was dependent on fetal bovine serum concentration and temperature of incubation. Serum concentrations of 5, 10, and 20% produced the highest survival during primary culture. Hepatocyte survival was in inverse proportion to the incubation temperature. Trout hepatocyte DNA synthesis and mitosis decreased during the culture period. Cytochrome p450 activity decreased rapidly during the first 2 d of culture and then remained low but measurable during the remaining 8 d of culture. Culture temperature also influenced the p450 activity with lower temperatures producing greater activity. Morphologic changes occurred in the cells during culture. Isolated hepatocytes self-aggregated, forming strands and clumps that increased in size with time in culture. Junctional complexes between cells were evident within the aggregates. Nuclear atypia, increases in size and number of autophagic vacuoles, and the appearance of bundles of intermediate filaments also were observed with increased time in culture.

Hematoporphyrin derivative photochemotherapy of experimental bladder tumors

Recent studies have shown that disruption of tumor blood flow is a major consequence of hematoporphyrin derivative photochemotherapy. A series of experiments was undertaken on the transplantable N-(4-(5-nitro-2-furyl)-2-thiazolyl)-formamide induced urothelial tumor in Fischer 344 rats to determine a dose response for both hematoporphyrin derivative and light. Tumor blood flow was used as the biologic criteria of response. Hematoporphyrin derivative doses of 10 micrograms./gm. body weight or above were necessary to cause a significant decrease in tumor blood flow when the tumors were illuminated with 360 joules/cm.2 of noncoherent red light (greater than 590 nm.). With a constant hematoporphyrin derivative dose of 20 micrograms./gm. body weight, significantly lower tumor blood flows were observed with fluences of 240 joules/cm.2 and above. In order to correlate dose response to tumor regression, experiments were done in which tumor dry weights were determined 3 weeks after completion of photochemotherapy (360 joules/cm.2). Hematoporphyrin derivative doses of 10 micrograms./gm. body weight or above were necessary to induce tumor regression. These studies support the hypothesis that disruption of tumor blood flow is a tumoricidal mechanism of hematoporphyrin derivative photochemotherapy.

Preliminary studies on the usefulness of medaka, Oryzias latipes, embryos in carcinogenicity testing

Medaka (Oryzias latipes) embryos were exposed continuously for 10 days to diethylnitrosamine (DENA) at concentrations of 25, 50, or 100 ppm. Following exposure and after hatching, the embryos were placed in clean, carcinogen-free water. Fish were sampled for pathological examination after 1 month, 3, and 6 months. Grossly visible liver tumors were evident after 3 months in 10 and 30% of the fish treated with 50 and 100 ppm DENA, respectively. Following 6 months exposure, 4% of the fish treated with 25 ppm, 15% of those given 50 ppm, and 43% of those treated with 100 ppm DENA contained liver tumors. Focal areas consisting of 10 to 40 highly basophilic cells in the liver were noted at all the exposure concentrations. The incidence of the focal areas increased proportionately with the concentration of DENA and the age of the fish. Liver tumors were examined by light and electron microscopy. Most of the hepatic tumors were moderate to well-differentiated trabecular hepatomas, although 2 cholangiomas and 2 poorly differentiated hepatomas were noted. No liver lesions or tumors were observed in controls.

Blood flow in transplantable bladder tumors treated with hematoporphyrin derivative and light

Following hematoporphyrin derivative (HPD) photochemotherapy, blood flow to transplantable N-[4-(5-nitro-2-furyl)-2-thia-zolyl] formamide-induced urothelial tumors was determined by a radioactive microsphere technique using either 103Ru or 141Ce. Two tumors were implanted s.c. on the abdominal wall of Fischer 344 weanling rats. HPD (10 mg/kg body weight) was administered 24 hr prior to phototherapy (red light, greater than 590 nm; 360 J/sq cm). One of the two tumors was shielded from light exposure and served as an internal control. Blood flows were determined in control animals that received no treatment (Group 1), HPD only (Group 2), or light only (Group 3). In Groups 4 and 5, animals received the combination of HPD and light but differed in the time interval between treatment and blood flow determinations (10 min and 24 hr, respectively). Only blood flow to tumors treated with HPD and light showed a significant decrease (p less than 0.05) when compared with their internal controls both at 10 min (Group 4) and 24 hr (Group 5) after completion of phototherapy. These studies suggest that disruption of tumor blood flow may be an important mechanism of action of this method of cancer therapy.

Ultrastructure of the liver and biliary tract in health and disease

Ultrastructural studies with the transmission (TEM) and scanning (SEM) electron microscopes have added greatly to our knowledge of cellular structure and function in the liver. The normal polyhedral hepatocyte has numerous subcellular organelles, such as mitochondria, peroxisomes, lysosomes and complex rough (rer) and smooth (ser) endoplasmic reticulum. The normal hepatocyte stores glycogen, and sometimes lipid droplets, and secretes bile through the bile canaliculi between adjacent liver cells. It receives nutrients from the sinusoidal lumen across a fenestrated endothelium which is separated by the Space of Disse' from the plasma membrane. The Space of Disse' contains a scant network of reticulin fibers but no basal lamina. Two types of parasinusoidal cells are found in Disse's space: the fat storing cells of Ito, and the Pit cells which may have an endocrine function. The diseased liver has yielded much information in studies with TEM and SEM. The studies with TEM have been most helpful in studying the etiology of infectious diseases such as hepatitis B; have revealed organelle changes such as megamitochondria in cirrhosis and the fibrillar nature of alcoholic hyaline; have led to the identification of specific deposits in metabolic and storage diseases such as hemochromatosis (iron). Wilson's disease (copper), and alpha-1-antitrypsin deficiency (glycoprotein) have proven useful in identifying drug induced liver cell changes such as proliferation of SER and cholestasis, and are useful for identifying specific cell types in inflammatory and neoplastic diseases. In the future, both TEM and SEM coupled with histochemical, cytochemical, immunohistochemical and other analytic techniques will continue to add greatly to our understanding of the liver in health and disease.

Morphologic and functional studies of mouse hepatocytes in primary culture

Mouse liver cells in primary culture were evaluated by high-resolution light microscopy (HRLM) and transmission electron microscopy (TEM). Cells after 2 hours of culture in L-15 medium supplemented with 10% fetal bovine serum were spherical in shape, and were either individual or in small clusters of up to ten cells. Following 1 day in culture, hepatocytes were flattened and usually found in groups. Bile canaliculus-like structures were apparent between hepatocytes. Tight junctions and desmosomes were also present along adjacent plasma membranes. Autophagic vacuoles were seen within the cytoplasm. After 2 days in culture, hepatocytes appeared more elongated and flattened than in earlier sampling periods. Both autophagic and clear vacuoles were seen in the cytoplasm. Mitochondria were present in a variety of shapes and sizes. Small bundles of microfilaments were frequently seen in the basal region of cross-sectioned cells. From the fourth until the eighth day in culture, hepatocytes displayed further progression of the morphologic changes seen after 2 days. Nuclear elongation and the projection of cytoplasmic pseudoinclusions into the nucleus were also evident after 4 days. Cytoplasmic and nuclear changes were eventually observed in all hepatocytes by the eighth day of culture. DNA synthesis in the cells during culture was investigated by autoradiography. The percentage of S-phase labeled cells was 0.1% after 1 day of culture. The labeling index increased to 1.02%, 3.14%, and 5.88% after 2, 4, and 6 days of culture, respectively. Synthesis of albumin by the liver cells was also detectable during the first 8 days of primary culture. A gradual drop in albumin synthesis was noted with increased time in culture. The percentage of hepatocytes that histochemically stained for gamma glutamyl transpeptidase (GGT) progressively increased from 0.01% of the cells after 2 hours culture to 3.14% of the cells after 8 days of culture.

Cellular effects of human leukocyte hydrolases. II. Ultrastructural studies on fibroblasts

Morphologic ultrastructural changes induced in human gingival fibroblasts in vitro by treatment with human neutrophil granule enzymes were studied. Surface mucopolysaccharide of the fibroblasts was examined by ruthenium red staining. The only alteration that could be identified was the removal of surface mucopolysaccharide after treatment with granule enzymes, but not when soybean trypsin inhibitor was present. When the cells were released from their growth surface they assumed the characteristics of floating cells rather than spreading fibroblasts, but were otherwise unremarkable.

Malignant fibrous histiocytoma. Cytologic, light microscopic and ultrastructural studies

Studies of the cytologic, light-microscopic and electron-microscopic features of three malignant fibrous histiocytomas (MFH) confirmed the presence of histiocytelike and fibroblastlike cells. The ultrastructural features suggest that the neoplasm possibly originates in undifferentiated mesenchymal cells that are capable of differentiating into histiocytic and fibroblastic cells. Cytologic features seen in smears obtained by thin needle aspiration included loose aggregates of markedly pleomorphic, elongated cells, histiocytelike cells and isolated bizarre giant cells. Phosphotungstic acid hematoxylin (PTAH) and oil red O staining of air-dried smears were helpful in differentiating MFH from pleomorphic variants of liposarcoma and rhabdomyosarcoma.

Mouse liver cell culture. II. Primary culture

Mouse hepatocytes in primary culture were characterized. Hepatocytes were isolated by the two-step hepatic portal vein perfusion method described previously. An optimal cell attachment of 43% was noted after 2 h incubation in 10% fetal bovine serum. Minimal attachment (less than 7%) occurred in serumless medium. Serum concentrations above 10% and attachment durations greater that 2 h resulted in no increased attachment of viable cells. Nonviable cells, however, progressively attached when both of these parameters were increased. Survival data of the cells in culture resembled those reported for rat hepatocytes in primary culture. A progressive decrease in survival was noted following initial attachment until only approximately 15% of initially plated cells remained viable and attached after 8 d culture. The decrease in survival was accompanied by morphologic changes including flattening and elongation of the cells, some multinucleation, and disruption of monolayer groups.

Metabolism and DNA binding of benzo[a]pyrene in cultured human bladder and bronchus

The metabolism of benzo[a]pyrene (BP) was examined in explant cultures of human bladder and bronchus. Three-day cultures were exposed to radiolabeled BP for 24 h, and the metabolism was determined by analysis of the level of binding of reactive metabolites to DNA, and by the release of metabolites into the medium. For a given individual, the DNA binding level and extent of metabolism was usually higher in the bladder than in the bronchus. In specimens obtained from 16 individuals, the average DNA-binding levels for BP-DNA adducts following a 24 h exposure to 1 microM BP were 6.4 +/- 5.0 mumol BP/mol deoxyribonucleotide for the bladder and 3.1 +/- 1.9 mumol BP/mol deoxyribonucleotide for the bronchus. The major BP-DNA adduct in both tissues co-chromatographed with one of the adducts formed by reaction of r-7, t-8-dihydroxy-t-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene with deoxyguanosine using high-pressure liquid chromatography. In tissues obtained from the same individual, the binding levels of BP metabolites to bladder cell DNA was not strongly correlated to that of bronchial cell DNA (r = 0.55). The medium of both tissues contained small amounts of free, unconjugated metabolites of BP (less than 3% of the total) and large amounts (30-86% of the total) of unidentified, highly polar material. Human bladder appears to be the most active explant tissue yet studied with respect to its ability to activate BP to DNA binding forms. The relevance of this observation to human bladder cancer is, as yet, unknown.

Mouse liver cell culture. II. Primary culture

Mouse hepatocytes in primary culture were characterized. Hepatocytes were isolated by the two-step hepatic portal vein perfusion method described previously. An optimal cell attachment of 43% was noted after 2 h incubation in 10% fetal bovine serum. Minimal attachment (less than 7%) occurred in serumless medium. Serum concentrations above 10% and attachment durations greater that 2 h resulted in no increased attachment of viable cells. Nonviable cells, however, progressively attached when both of these parameters were increased. Survival data of the cells in culture resembled those reported for rat hepatocytes in primary culture. A progressive decrease in survival was noted following initial attachment until only approximately 15% of initially plated cells remained viable and attached after 8 d culture. The decrease in survival was accompanied by morphologic changes including flattening and elongation of the cells, some multinucleation, and disruption of monolayer groups.

Mouse liver cell culture. I. Hepatocyte isolation

A method for isolation of mouse liver cells by a two-step perfusion with calcium and magnesium-free Hanks' salt solution followed by a medium containing collagenase is described. Several variations of the commonly used procedure for rat liver cell isolation were quantitatively compared with respect to cell yield and viability. The optimal isolation technique involved perfusion through the hepatic portal vein and routinely produced an average of 2.3 x 10(6) viable liver cells/g body weight. Optimal perfusate collagenase concentration was found to be 100 U of enzyme activity per milliliter of perfusate. Light and electron microscopic evaluation of liver morphology after several steps of the isolation showed distinct morphologic changes in hepatocytes and other liver cells during perfusion. After perfusion with Hanks' calcium- and magnesium-free solution, many hepatocytes exhibited early reversible cell injury. These changes included vesiculation and slight swelling of the endoplasmic reticulum as well as mitochondrial matrix condensation. Subsequent to perfusion with collagenase, the majority of hepatocytes appeared connected to one another only by tight junctional complexes at the bile canaliculi. Multiple evaginations were seen on the outer membrane resembling microville and probably represented the remains of cell-to-cell interdigitations between hepatocytes and sinusoidal lining cells from the space of Disse. The cytoplasmic injury seen after Hanks' perfusion was reversed after collagenase perfusion. After mechanical dispersion, isolated mouse hepatocytes were spherical in shape and existed as individual cells; many (80 to 85%) were binucleated under hase contrast light microscopy. By electron microscopy, cells appeared morphologically similar in cytoplasmic constitution to that seen in intact nonaltered liver cells.

Biology of hepatocellular neoplasia in the mouse. II. Sequential enzyme histochemical analysis of BALB/c mouse liver during safrole-induced carcinogenesis

Sequential alterations in enzyme histochemical profiles and reaction of hepatocytes to rapid iron overload were examined in male BALB/c mice during chronic, safrole exposure. At 24 weeks after initiation of safrole treatment, foci of enzyme-altered hepatocytes were noted. These foci were composed of cells showing a decrease in reactivity for glucose-6-phosphatase (Glc-6-Pase) and succinate dehydrogenase (SDH) and an increase for gamma-glutamyl transpeptidase (gamma-Glu-T). In control, iron-loaded mice, the livers were intensely siderotic. In safrole-exposed, iron-loaded mice, foci of iron-negative hepatocytes, varying from a few cells to a lobule in diameter, were initially noted at 24 weeks. Both enzyme-altered and iron-negative foci occurred in the livers of exposed mice at all time periods after 24 weeks. After 36, 52, and 75 weeks of safrole treatment, hepatocellular adenomas were noted with altered enzyme histochemical profiles. Hepatocytes from adenomas were characterized by a decreased staining for Glc-6-pase and SDH and increased staining for gamma-Glu-T and glucose-6-phosphate dehydrogenase (Glc-6-PD). In addition, a few nodules showed a decrease in staining for 5'nucleotidase. In iron-loaded mice, hepatocytes of adenomas showed a decreased to negative reaction for iron when the surrounding parenchyma was siderotic. Hepatocellular carcinomas (HPC) occurred in livers of mice exposed to safrole for 52-75 weeks. The cells of HPC displayed similar enzyme histochemical reactions as cells of adenomas. They were decreased for Glc-6-Pase and SDH activity and increased for gamma-Glu-T and Glc-6-PD. In iron-loaded mice, the HPC cells were negative for stainable iron. Foci, adenomas, and HPC displayed some variability in enzyme histochemical reactions. Variability existed between lesions as well as between cells of the same lesion.

Unusual ultrastructural features in a case of acute diffuse proliferative glomerulonephritis

A case consistent with recurrent acute poststreptococcal glomerulonephritis but with atypical features is described. Light microscopy revealed a diffuse proliferative glomerulonephritis. A spectrum of ultrastructural features, from the typical "humpy bumpy" subepithelial deposits to the apparent disappearance of the deposits within the epithelial cells, is presented. An unusual piling up of basement membrane material around the deposits is described, together with some areas showing an appearance reminiscent of membranous glomerulopathy. Resorption of the dense deposits within epithelial cells is suggested and a hypothesis advanced that the basement membrane reaction may indicate an incipient chronic immune complex lesion.