Incidence of nonneoplastic lesions in historical control male and female Fischer-344 rats from 90-day toxicity studies

The incidence of all spontaneously occurring histologic lesions was determined for control Fischer-344 (F-344) rats from 90-day (13-wk) prechronic National Toxicology Program (NTP) toxicity studies. A total of 319 rats, represented by control groups of 10 males and 10 females each from dosed feed (n = 8), inhalation (n = 4), and gavage (n = 4) studies were included in the review. All protocol required tissues routinely collected for evaluation were reexamined for potential nonneoplastic and neoplastic lesions. Histopathologic findings in tissues included a spectrum of degenerative and inflammatory lesions. The most common lesions in male rats were nephropathy [145/160 (90.6%)] and cardiomyopathy [125/158 (79.1%)]. These changes were also present in the female rats, however, at much lower incidence rates [nephropathy = 30/157 (19.1%); cardiomyopathy = 36/158 (22.8%)]. Other less frequently occurring lesions included inflammation of the preputial [36/152 (23.7%)] and clitoral [34/155 (21.9%)] glands and inflammation of the liver consisting of either foci of mononuclear inflammatory cells [19/159 (11.9%) in males and 33/159 (20.8%) in females] or focal granulomatous inflammation [1/159 (0.6%) in males and 14/159 (8.8%) in females]. Pancreatic acinar cell atrophy occurred in both males [11/160 (6.9%)] and females [8/159 (5.0%)]. A variety of other less common nonneoplastic lesions were identified in both sexes of rats. Also recorded in this review are histologic changes generally considered to be components of the normal morphology of a particular tissue or organ for the F-344 rat (i.e., extramedullary hematopoiesis and hemosiderin deposition in the spleen, renal mineralization, uterine dilation, etc.). These findings were included and discussed due to potential treatment effects that may result in an increase or decrease in these changes compared to controls. Neoplasms were not observed in rats from the prechronic studies evaluated.

Comparative and collaborative evaluation of standardization of antifungal susceptibility testing for filamentous fungi

The purpose of the study was to evaluate the interlaboratory agreement of broth dilution susceptibility methods for five species of conidium-forming (size range, 2 to 7 microns) filamentous fungi. The methods used included both macro- and microdilution methods that were adaptations of the proposed reference method of the National Committee for Clinical Laboratory Standards for yeasts (m27-P). The MICs of amphotericin B, fluconazole, itraconazole, miconazole, and ketoconazole were determined in six centers by both macro- and microdilution tests for 25 isolates of Aspergillus flavus, Aspergillus fumigatus, Pseudallescheria boydii, Rhizopus arrhizus, and Sporothrix schenckii. All isolates produced clearly detectable growth within 1 to 4 days at 35 degrees C in the RPMI 1640 medium. Colony counts of 0.4 x 10(6) to 3.3 x 10(6) CFU/ml (mean, 1.4 x 10(6) CFU/ml) were demonstrated in 90% of the 148 inoculum preparations. Overall, good intralaboratory agreement was demonstrated with amphotericin B, fluconazole, and ketoconazole MICs (90 to 97%). The agreement was lower with itraconazole MICs (59 to 79% median). Interlaboratory reproducibility demonstrated similar results: 90 to 100% agreement with amphotericin B, fluconazole, miconazole, and ketoconazole MICs and 59 to 91% with itraconazole MICs. Among the species tested, the MICs for S. schenckii showed the highest variability. The results of the study imply that it may be possible to develop a reference method for antifungal susceptibility testing of filamentous fungi.

Pulmonary response of Fischer 344 rats to acute nose-only inhalation of indium trichloride

We have previously shown that rats dosed intratracheally with indium trichloride (InCl3) develop severe lung damage and fibrosis. However, it is not clear what pulmonary effects would result following accidental occupational exposure to low concentrations of indium by inhalation. The present study uses a model of acute lung injury based on single 1-hr nose-only exposures to 0.2, 2.0, or 20 mg InCl3/m3. Exposure to 0.2 mg InCl3/m3 was capable of initiating an inflammatory response. Seven days following inhalation of 20 mg InCl3/m3 the total cell number, fibronectin, and TNF alpha levels in the bronchial alveolar lavage fluid were 8, 40, and 5 times higher than the control, respectively. Commensurate with the level of lung injury 7 days after exposure, an acute restrictive lung lesion and increased airway responsiveness to acetylcholine were observed. Forty-two days after exposure a compensatory increase in lung volume and carbon monoxide diffusing capacity in the 20 mg InCl3/m3 group suggested recovery from the lung injury. Lung collagen levels were increased in a concentration-dependent manner 42 days postexposure. These data indicate that inhalation of InCl3/m3 causes acute inflammatory changes in the lung.

Inhibition of lung immunity after intratracheal instillation of benzo(a)pyrene

Benzo(a)pyrene (B(a)P) has been shown to suppress systemic immunity in experimental animals, which may contribute to the growth of the chemical-induced tumors. However, its effects on lung immunity after inhalation, a common route for human exposure in urban areas, has not been determined. These studies examine intratracheal B(a)P instillation on lung natural killer (NK) cell activity, alveolar macrophage (AM) functions, and susceptibility to tumor cell challenge in Fischer 344 (F-344) rats. Adult female F-344 rats were given a single intratracheal instillation of 0, 10, 20, or 40 mg B(a)P/kg body weight as a suspension, and lung NK cell activity and AM functions were examined 7, 21, or 100 d later. Although exposure to B(a)P did not alter cell recovery after lavage, histologic changes were observed as evidenced by granulomatous inflammation and squamous metaplasia. There was a slight but significant suppression of H2O2 and nitric oxide (NO) release from alveolar macrophages of treated animals as well as NK cell activity from the lung digest. A marked suppression of tumor necrosis factor-alpha (TNF alpha) and interleukin (IL-1) secretion in LPS- and/or cytokine-activated alveolar macrophages occurred. The suppressive effects were generally more severe on Day 7 after exposure than on Days 21 or 100, although IL-1 remained depressed through Day 100 after exposure. B(a)P exposure allowed for the increased growth of MADB106 metastatic tumor cells in the lung. These tumor cells were shown to be highly sensitive to lysis by immune-mediators, including TNF alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

"Lipomatous" lesions of unknown cellular origin in the liver of B6C3F1 mice

The gross, microscopic, and ultrastructural features of lipomatous lesions in the liver of B6C3F1 mice are described. The cases were selected from a database of 45,406 male and 45,674 female mice used as treated, control, or vehicle-control animals in the National Cancer Institute's Bioassays or the National Toxicology Program's 2-year carcinogenicity studies. Thirteen hepatic lesions identified from cases within the database were re-evaluated microscopically and selected for further study. These lesions were present in ten males and three females that were between 85 and 113 weeks of age at the time of death. Grossly, the liver lesions were described as white to yellow or red to brown nodules/masses or foci that ranged from 2.0 to 25 mm in diameter. The lesions commonly involved the median and left lateral hepatic lobes. Microscopically, many of the lesions closely resembled lipomas described in the liver of human beings, and they consisted of nonencapsulated mature adipose-like tissue with irregular margins. The majority of the cells that comprised the lipomatous lesions were signet-ring shaped. These cells were positive for lipid as evidenced with oil red-O. The lipid droplets were also present within the hepatocytes that comprised the hepatic plates trapped within or surrounding many of the lipomatous lesions. At the margins of many of the lesions there were spindle-shaped cells that contained small intracytoplasmic lipid vacuoles. These cells were often within a stromal matrix that had focal areas of collagen and mucopolysaccharides, as evidenced by weak staining with Masson's trichrome and periodic acid-Schiff's stains, respectively. There was also disruption of the reticulum fibers in many of the lesions, as noted with a Gomori's reticulum stain. Ultrastructurally, cytoplasmic organelles, such as rough endoplasmic reticulum, free ribosomes and small lipid vacuoles, were present in the spindle-shaped cells, whereas signet-ring-shaped cells had few discernible organelles due to peripheral compression of the cytoplasm by single large vacuoles occupying the cytoplasmic space. The spindle-shaped cells were free of lysosomes. Thin collagen fibers were seen in contact with some of the spindle-shaped cells and were located between these cells and adjacent hepatocytes, or endothelial cells lining sinusoidal capillaries. A distinct basal lamina was not associated with spindle- or signet-ring-shaped cells. Similar lipomatous lesions were not found in other visceral organs. The exact cellular origin of the hepatic lesions described here is not known.

Pulmonary toxicity to intratracheally administered indium trichloride in Fischer 344 rats

The use of indium by the semiconductor industry has risen sharply in recent years with the discovery that the electrical properties of compounds such as indium phosphide and indium arsenide are better than those of silicon. However, relatively little is known about its potential to induce lung damage. These studies examined the effect of indium trichloride (InCl3) on the lung. To examine the disposition and removal of InCl3 from the lung, groups of female Fischer 344 rats received a single intratracheal dose of 1.3 mg In/kg as InCl3 and were euthanized after 1, 2, 4, 7, 14, 28, and 56 days at which time lung samples were analyzed for metal content. Furthermore, the histology, hydroxyproline levels, and bronchoalveolar lavage (BAL) fluid cellularity of the lung were studied. In addition, the effect of 0.00016, 0.00325, 0.065, and 1.3 mg In/kg on inflammatory response and BAL fluid cellularity was compared. While a dose as low as 0.00325 mg In/kg was capable of initiating an influx of inflammatory cells, instillation of 1.3 mg In/kg resulted in an inflammatory response that was still evident 56 days later. After 28 days, the lung weight of the InCl3-treated animals was 2.5 times greater than that of the controls. The total cell number in the BAL fluid of the treated animals after 28 days was 32 times higher than that in the control rats. Sixty-seven percent of these cells were granulocytes. Compared to the controls, the hydroxyproline content of the lungs from the InCl3-treated animals were two-fold greater after 28 and 56 days. Furthermore, the levels of fibronectin and TNF alpha present in the BAL fluid of InCl3-treated rats increased sharply during the first 24 hr and remained elevated 56 days later. These data and the histological examination of the lung following InCl3 treatment suggest that InCl3 is capable of causing severe lung damage and the development of fibrosis.

Design and synthesis of novel cyclic RGD-containing peptides as highly potent and selective integrin alpha IIb beta 3 antagonists

Utilizing conformational constraints in conjunction with various structural considerations, we have synthesized a series of cyclic disulfide peptides that are highly potent and selective antagonists for the platelet integrin alpha IIb beta 3 (GPIIb/IIIa). The affinities of the peptides for alpha IIb beta 3 were determined by platelet aggregation assays and an alpha IIb beta 3 ELISA. Their affinities for alpha 5 beta 1 and alpha v beta 5 integrins were also determined in respective ELISA assays. Structure-activity relationship studies suggest that R-G-D-Ar-R (Ar = hydrophobic residue) is the essential pharmacophore that is responsible for their high alpha IIb beta 3 binding affinity, very high selectivity, and distinct biological properties. One of these analogues, TP9201, has been shown to inhibit platelet-mediated thrombus formation without associated prolongation of template bleeding time. The arginine residue adjacent the carboxy terminus of the R-G-D-Ar sequence could function as the biological effector element that determines this distinct and unexpected biological property.

Evaluation of ketamine-xylazine in Syrian hamsters

Few parenteral anesthetics are safe and effective in the Syrian hamster. This study evaluated the anesthetic efficacy and potential for tissue damage of ketamine-xylazine (KX). Two dosage levels were administered intraperitoneally. Ketamine at 50 mg/kg combined with 10 mg/kg xylazine did not produce a consistent, reliable level of immobilization or anesthesia. Ketamine at 150 mg/kg combined with 10 mg/kg xylazine administered IP produced an adequate level of anesthesia without tissue damage for most procedures, but supplementation with lidocaine was necessary for peritoneal incision. Careful positioning of male hamsters for IP injection is imperative to prevent inadvertent injection into the testes with subsequent tissue damage.

The novel metallothionein genes of Caenorhabditis elegans. Structural organization and inducible, cell-specific expression

Two genes (mtl-1 and mtl-2) that encode the novel metallothioneins (MTs) of Caenorhabditis elegans (CeMTs) were cloned and characterized. Both genes contain a single intron that interrupts codon 6 and short 3'-untranslated regions. However, their promotor regions are distinctively non-homologous. The mtl-2 promoter contains a TATAA box and a single putative metal regulatory element. These elements are absent in the mtl-1 promoter. Nevertheless, both CeMT1 and CeMT2 mRNAs are induced by cadmium and contain precisely initiated, 5'-untranslated sequences. The inducibility and cell type specificity of metallothionein gene expression were investigated in transgenic C. elegans that carry the lacZ (beta-galactosidase) reporter gene under the control of an mtl-1 or mtl-2 promoter sequence. Upon treatment of transgenic C. elegans with cadmium or heat stress, the mtl-2:lacZ fusion gene is abundantly and exclusively expressed in the intestinal cells of larvae and adult animals. Expression is not detected in the absence of metal or heat shock. In contrast, an mtl-1:lacZ construct is constitutively expressed in the pharynx and induced by cadmium and heat shock in the intestinal cells of C. elegans larvae. The metal-inducible expression of the mtl-1:lacZ gene is attenuated in adult transgenic nematodes. Thus, the activity of each mtl promoter is modulated by metals as well as developmental and environmental factors.

Microvascular hemodynamics in the sickle red blood cell perfused isolated rat lung

In this study the effects of alveolar hypoxia on pulmonary microvascular hemodynamics in sickle red blood cell (HbSS-RBC) perfused rat lungs were studied under conditions of high and low oxygen tensions and compared with lung perfused with rat (HbRat) and normal human (HbAA) RBC controls. Independent of the RBC suspension (hematocrit 5%) used, ventilation with the room air gas mixture did not result in any significant differences in the pulmonary arterial pressure (Ppa), capillary pressure (Ppc), total pulmonary vascular resistance (RT), or angiotensin II pressor response. Ventilation of HbSS-RBC perfused lungs with a hypoxic gas mixture significantly increased the Ppa, Ppc, and RT above that which was seen in HbRat and HbAA controls. The increase in RT occurred mainly in the pulmonary artery independent of RBC suspension. In addition, no significant accumulation of lung water occurred in HbSS-RBC perfused lungs compared with HbRat and HbAA controls, as indicated by the change in capillary filtration coefficient and wet-to-dry lung weight ratio. In conclusion, deoxygenation of the HbSS-RBC and hypoxic pulmonary vasoconstriction is additive in altering pulmonary microvascular hemodynamics.

Evaluation of Telazol-xylazine as an anesthetic combination for use in Syrian hamsters

The availability of safe parenteral anesthetics for use in Syrian hamsters is limited. We evaluated the effects of Telazol-xylazine (TZX) combinations with respect to anesthetic efficacy and potential for tissue damage. Two dose levels of the combination were administered by both the intraperitoneal (IP) and intramuscular (IM) routes. TZX by the IM route failed to consistently produce anesthesia and caused gross and histopathologic muscle lesions. IP administration of 20 mg/kg Telazol combined with 10 mg/kg xylazine was adequate for restraint purposes. IP administration of 30 mg/kg Telazol combined with 10 mg/kg xylazine produced a safe, reliable level of surgical anesthesia without evidence of gross or histopathologic lesions. There was no nephrotoxicity at either concentration of the anesthetic. A dose level of TZX that provides safe parenteral anesthesia in Syrian hamsters was determined.

Confocal laser scanning immunofluorescence microscopy of lamellar bodies and pulmonary surfactant protein A in isolated alveolar type II cells

We have determined the distribution of surfactant protein A (SP-A) in isolated type II cells from the lungs of rats by using immunofluorescence in conjunction with a laser scanning microscope fitted with a confocal aperture. Because of the very narrow depth of field of this microscope (less than 0.4 microns) in the confocal format, we were able to optically section type II cells and determine both the distribution of SP-A in the type II cell and the distribution of the lamellar bodies. The location of SP-A was determined by using fluorescein isothiocyanate-labeled secondary antibodies and the lamellar body distribution by using the lipid soluble fluorescent stain Phosphine 3R. SP-A was detected in the cytoplasm of type II cells as asymmetrically distributed punctate fluorescent bodies that resembled lamellar bodies in terms of size, number, and distribution within the cytoplasm of the cell. Most of the SP-A was located within bodies of the type II cell. Diffuse patches of fluorescence were seen in other cytoplasmic regions as well as the number of the cell. We conclude that SP-A is localized primarily, but not exclusively, in lamellar bodies of type II cells and that laser scanning microscopy is a much superior technique for the localization of SP-A than conventional microscopy in terms of both sensitivity and resolution.

Multivariate analysis of prognostic factors in stage IV follicular low-grade lymphoma: a risk model

We analyzed the records of 96 previously untreated patients with stage IV follicular low-grade lymphoma (FLGL) uniformly treated with cyclophosphamide, doxorubicin, vincristine, prednisone, and bleomycin (CHOP-Bleo) chemotherapy from 1972 to 1982. The overall complete remission (CR) rate was 77%. At a median follow-up of 138 months, the 10-year cause-specific survival rate was 42% with a median survival of 100 months. Failure-free survival (FFS) was 15% at 10 years with a median FFS of 30 months. Multivariate analysis showed peripheral lymph node size (LN), degree of marrow involvement, and sex, in that order, to be important for FFS, while the number of extranodal sites (#ENS), LN, sex, and degree of marrow involvement were important for cause-specific survival. We devised a tumor burden (TB) model, incorporating #ENS, LN, and degree of marrow involvement. Three groups were identified with statistically significant differences in cause-specific survival and FFS. Those with low TB (one ENS exclusive of extensive marrow and nodal disease less than 5 cm) had a 10-year cause-specific survival of 73% compared with 24% for patients with high TB (greater than or equal to two ENS and nodal disease greater than or equal to 5 cm) (P less than .001) and 40% for those with intermediate TB (either greater than or equal to 2 ENS, or extensive marrow only, or nodal disease greater than 5 cm) (P = .050). Patients with low TB had a 10-year FFS rate of 32%, while the intermediate and high TB groups had 10% and 9% FFS, respectively (P = .003). Because sex was a very strong prognostic variable, we created a risk model for survival and FFS based on TB and sex. Females with low TB had the best prognosis (92% survival and 50% FFS at 10 years) and males with high TB had the worst outlook (median survival and FFS, 43 and 12 months, respectively). Other TB-sex combinations defined two groups with statistically significant differences in survival but comparable FFS. This model should aid in the design and analysis of future trials.

Histomorphology and ultrastructure of spontaneous pulmonary neoplasms in strain A mice

The microscopic and ultrastructural characteristics of spontaneous pulmonary neoplasms in strain A (strA) mice are described. Fifty-one spontaneous lung tumors were identified in 34 out of 57, 11-23-month-old male strA/Hen mice. Grossly, all tumors appeared as yellow-white, discrete nodules ranging in size from 1.0-10 mm. Tumor types were randomly distributed throughout the lung; however, the right lung lobes were most frequently involved. Histologically, tumors were classified as adenoma (34/51) or carcinoma (17/51) as defined by standard histopathologic criteria. Adenomas were usually less than 4 mm in diameter and had solid (16/34), papillary (10/34), or mixed (8/34) histologic growth patterns. Carcinomas were usually greater than 4 mm in diameter and had papillary (13/17) or mixed (4/17) histologic growth patterns. Ultrastructurally, benign tumors consisted of solid or papillary areas of neoplastic type II-like cells. Cells comprising malignant tumors had varying ultrastructural characteristics ranging from well-differentiated alveolar cell types to undifferentiated cells having intracytoplasmic osmiophilic dense bodies, vacuoles, or few specialized organelles commonly observed in mature nonneoplastic pulmonary epithelial cells.

Molecular basis of the activation of the tumorigenic potential of Gag-insulin receptor chimeras

A previous study showed that the human insulin receptor (IR) could be activated by insertion of a 3' portion of the cDNA encoding the beta subunit into a retrovirus genome to form a Gag-IR fusion protein. While capable of transforming cells in culture, this IR cDNA-containing virus, called UIR, was not able to induce tumors in animals. Subsequently, we isolated a spontaneous sarcomagenic variant called UIR19t from the parental UIR. UIR19t was molecularly cloned, sequenced, and found to harbor two mutations. A 44-amino acid deletion immediately upstream from the transmembrane domain of the Gag-IR fusion protein removes all the extracellular sequence of the IR remaining in the original UIR construct. In addition, a single nucleotide deletion at the 3' end results in truncation and replacement of the carboxyl-terminal 12 amino acids by 4 new amino acids. The specific kinase activity of UIR19t is 4- to 5-fold higher than that of the parental UIR. However, no new cellular substrates were detected in UIR19t-transformed cells as compared to UIR cells. Viruses containing either the 5' or the 3' deletion mutation were constructed and assessed for their biological function. Our data indicate that the 5' deletion alone is sufficient to confer tumorigenic ability. We conclude that sequence immediately upstream from the transmembrane domain imposes a negative effect on the transforming and tumorigenic potential of the Gag-IR fusion protein.