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Primary Rauscher leukemia virus (RLV)-induced myeloid leukemias can produce many small clones in agar in the absence of a factor needed for the proliferation of normal myeloid cells. It seems that leukemic cells can more efficiently utilize the small amount of colony-stimulating factor (CSF) that is produced by them. At optimal stimulation by exogenous CSF, leukemic cells exhibit a poorer rate of proliferation than normal bone marrow cells. Hemopoietic cells can replicate the virus after infection in vitro. In some experiments, infection of normal bone marrow cells leads to the production of some cells with the same growth pattern as cells from primary leukemias.

Purpose. The use of intracerebral microdialysis as a tool to measure the penetration of anticancer agents in brain tumor was investigated.

Lethally irradiated C3H/Law mice were injected (i.v.) with C57BL/Rij allogeneic bone marrow cells to induce a delayed type graft-vs-host disease (GVHD). Signs of GVHD first became apparent in the third week after transplantation. The disease resulted in a mortality rate of 70% at 80 days. Treatment with IFN-gamma twice weekly, for a period of 6 wk, starting at the time of bone marrow transplantation (BMT), completely prevented overt GVHD, as evidenced by a lack of diarrhea and no mortality during the follow-up period of 100 days after BMT. Also, the histologic GVHD lesions in the gastrointestinal tract were almost completely abrogated by the IFN-gamma treatment. All long term survivors were proven to be chimeras. During the induction phase of GVHD, the number of Con A-induced, IFN-gamma-producing cells in the spleen was significantly reduced in the IFN-gamma-treated mice as compared with control mice. These results suggest that the normally enhanced production of endogenous IFN-gamma in the spleen at the time of hematopoietic reconstitution after BMT is down-regulated by exogenously administered IFN-gamma. This cytokine-mediated strategy to prevent GVHD might be an alternative to the current strategy of in vitro depletion of T cells for allogeneic BMT.

The induction of experimental arthritis in rhesus monkeys was studied by intradermal immunization of bovine type II collagen and antigens derived from Mycobacterium tuberculosis, Streptococcus pyogenes, and Eubacterium aerofaciens. The tested bacterial antigens proved to be not arthrogenic. Bovine type II collagen induced clinical arthritis in 50% of the rhesus monkeys. Type II collagen induced arthritis in rhesus monkeys proved to be a potential model to study clinical, serological, histological, genetic, and immunologic features associated with human RA.

High doses of adenotk were injected into the cerebrospinal fluid of rats and nonhuman primates (Macaca mulatta). Vector administration was followed by ganciclovir administration for 14 days. Despite the absence of clinical symptoms, analysis of the cerebrospinal fluid (CSF) and histopathological examination of the central nervous system (CNS) of the monkeys (3 weeks after vector injection) were consistent with a viral meningitis. Immunohistochemical analysis of the inflammatory infiltrates in the monkeys revealed the presence of T and B lymphocytes, indicating a combined cellular and humoral immune response to the vector. This latter was supported by the finding of intrathecal anti-adenovirus antibody synthesis. Rats receiving high intrathecal adenotk doses showed a transient and dose-dependent clinical toxicity consisting of lethargy, hyperemic eyes and weight loss. Histopathological examination of the meninges showed a shift from polymorphonuclear infiltrates during the first post-injection days to clusters of mononuclear cells after 7 days. Acute toxicity is probably related to the early, innate immune response to the vector. In a separate experiment, high levels of IL-8 and IL-6, were measured during the first 2-3 post-injection days in the CSF of two monkeys which received intrathecal adenoLacZ. Therefore, these cytokines seem to play an important role in initiating the nonspecific immune response. In one monkey which received adenotk, recombinant adenovirus was cultured from serum samples obtained at the 7th post-injection day. At this time-point, no vector could be isolated from CSF samples. Based on these preclinical data, we recommend careful dose finding for clinical studies that aim to treat patients with leptomeningeal metastases.

Chronic proliferative dermatitis is a spontaneous mutation in C57BL/Ka mice (cpdm/cpdm), showing alopecia, epithelial hyperproliferation, infiltration by eosinophils and macrophages, and vascular dilatation. To further elucidate its pathogenesis, organs of 1-, 2-, 3-, 4-, 5-, and 6-week-old cpdm/cpdm mice were examined. At 4 weeks, the epidermal thickness was increased, whereas already at 3 weeks, the bromodeoxyuridine incorporation was increased in the basal keratinocytes. However, already at the age of 1 week, skin, lungs, and lymph nodes were infiltrated by eosinophils although no macroscopic lesions were present. Compared with control animals, 6-week-old cpdm/cpdm mice had decreased serum IgE levels and increased numbers of mast cells. From the age of 1 week these mast cells became increasingly IgE positive. In contrast, the mast cells of the control animals remained IgE negative. Mast cells of control and cpdm/cpdm mice were interleukin-4 and tumor necrosis factor-alpha positive. A likely explanation for the tissue infiltration of eosinophils could be the release of interleukin-4 and tumor necrosis factor-alpha from activated mast cells. Tumor necrosis factor-alpha may lead to the expression of E-selectin on endothelial cells, facilitating interleukin-4-mediated eosinophil transendothelial migration. Although various pathogenetic aspects of the cpdm/cpdm mouse need further elucidation, this model can be a tool to study eosinophil infiltration, leukocyte-endothelial cell interactions, and mast cell proliferation. Furthermore, the cpdm/cpdm mouse can be used to study chronic inflammatory skin disease because of the severe epidermal proliferation.

In the present paper the time course of brain tissue changes as evoked by a microdialysis probe and repeated dialysis procedures was examined by semiquantitative histology. The reactions to the presence of the probe as such were minimal. However, after more than two repeated perfusion procedures, tissue scores of hypercellularity and infiltration of granulocytes increased. It is concluded that the frequent use of repeated dialysis procedures may give rise to tissue effects parallelled by changes in BBB permeability. This has to be taken into account when intracerebral microdialysis is applied repeatedly within the same animal.

The use of intracerebral microdialysis as a tool to measure the penetration of anticancer agents in brain tumor was investigated.Following intravenous (iv) administration of 75 mg/kg. concentration-time profiles of methotrexate (MTX) were determined in brain cortical dialysate and in plasma. The individual ratio of the area under the curve of MTX in brain dialysate over that in plasma (MTX penetration) was determined in normal brain, in tumor-bearing brain and in brain after sham tumor implantation. Individual brains were examined histologically on the presence of tumor, as well as for other factors that might influence local MTX penetration. Histological scores were related to the individual data on penetration of MTX.MTX penetration values were higher in cortical brain at the site of the tumor, as compared to the levels measured in normal or sham implanted brain (mean increase to 250%). In the cortical brain contralateral to the tumor, MTX penetration values were found to be lower than in normal brain (mean reduction of 65%). Furthermore, it appeared that in the absence of tumor tissue, the presence of exudate around the probe was independently associated with increased penetration of MTX into the brain.Tumor tissue appeared to be the most important parameter in changing local MTX penetration in brain after tumor implantation. In general, it is anticipated that intracerebral microdialysis combined with histological examination can be used to investigate effects of brain tumor presence on regional (periprobe) penetration of anticancer drugs into the brain.

We have administered replication defective recombinant adenovirus harboring the human CFTR cDNA (Ad.CFTR) to lungs of Rhesus monkeys and assessed toxicity, efficiency of gene transfer and containment of recombinant adenovirus in the lungs. Gene transfer efficiencies, as measured by PCR analysis, were dose-dependent. Administration of low dose Ad.CFTR [1.5 x 10(7) plaque forming units (p.f.u.)] was not accompanied by any clinical chemical or histopathological changes. Mild to moderate multifocal perivascular and peribronchial lymphocytic infiltrates were found upon histopathological analysis only after administration of a high dose of recombinant adenovirus, although not accompanied by changes in clinical chemical parameters. Long-term expression (up to 128 days) was found after administration of recombinant adenovirus. Re-challenging of the monkeys treated with high-dose recombinant adenovirus resulted again in gene transfer at all levels of lungs and airways, without being accompanied by additional histopathological changes. Circulating anti-adenovirus antibodies were elicited. Animals treated with high-dose adenovirus secreted virus in pharynx and faeces for maximally 2 and 4 days after administration, respectively. These results show that recombinant adenovirus can be used for efficient delivery of genes into primate airway epithelium without signs of severe toxicity.

Bone is subject to continuous remodeling throughout life. The age-related loss of (trabecular) bone, leading to senile osteopenia, is mainly due to impaired bone formation. Osteoblasts (OB) and osteoclasts (OC) have been identified as playing a crucial role in the process of bone turnover, but the contribution made by their precursors is not well documented. We analyzed the cells of the osteoblast and osteoclast cell lineage along the trabecular bone of tibiae and the stromal cells in the marrow of aging BN/Bi Rij rats using electron microscopy. It appeared possible to distinguish preosteoblasts (pre-OB), OB, preosteoclasts (pre-OC), OC, and inactive bone-lining cells. Periods of increase, the maximal peak, and the decrease in trabecular bone volume were defined by means of morphometric measurements of trabecular bone volume. We found a decrease of more than 10-fold in the number of OB with age, but the numbers of pre-OB, pre-OC, and OC expressed per unit bone length, although variable, were age independent. The relative bone resorption and formation surface, expressed as a percentage of the total bone surface, decreased 2- and 15-fold, respectively. In 2-year-old animals the total volume of stromal cells, part of which constitutes the stem cell compartment of the osteogenic lineage, was a quarter of that found in 1-month-old animals and a third of that found in 6-month-old animals. The loss of trabecular bone is concomitant with a sharp increase in the ratio of pre-OB/OB, the ratio of OC/OB, and in the ratio of resorption to formation surfaces. There was no relation between the ratio of pre-OC/OC with age. These data lead to the conclusion that the main factor causing bone loss with age is a diminished maturation of pre-OB into OB.

The propensity of tumours to generate resistant clones is a major barrier to cytotoxic and hormone therapy. The vasculature of malignancies is a more appealing target, since tumour endothelial cells are not known to be tranformed or subject to somatic mutation or random phenotypic variation. Thus an effective anti-angiogenic therapy need not be vitiated by the acquisition of resistance. Although several antiangiogenic agents have been described and used in experimental models, there remain severe problems about optimising their use and about setting up informative clinical trials. These difficulties arise predominantly because of the “invisible” nature of tumour angiogenesis.

It is now generally recognized that carcinogenesis is the most important detrimental effect in man after low dose irradiation. The carcinogenic action of ionizing radiation is clearly demonstrated after exposure to relatively high doses (in excess of 0.5 Gy) but for the lower dose levels reliable direct observations are not available.

The risks of total-body irradiation with large doses of X rays (average dose 6.7 Gy) and fission neutrons (average dose 3.4 Gy) were investigated by keeping a group of long-term surviving monkeys from an experiment on acute effects under continuous observation. On the basis of the number of animals developing tumors in each group as a function of the total observation period and the average absorbed dose, relative biological effectiveness (RBE) values between 4 and 5 have been derived at these high dose levels. In experiments on mammary carcinogenesis in rats the highest RBE values are observed for neutrons with energies of 0.43 to 1 MeV as produced by the p + T reaction or by the fission process. Based upon linear dose-response curves for neutrons and X rays, a maximum RBE value of 15 was observed for induction of adenocarcinomas in WAG/Rij rats. Appreciably higher RBE values would be obtained if the results of the gamma-ray exposure, indicating a nearly quadratic dose-response relationship, were used as a baseline. For radiation protection applications it should be realized, however, that such an increase will be caused by the lower efficiency of low-linear-energy-transfer radiation rather than by an increase in efficiency of the neutron irradiation at low doses.

During its lifespan, the multi-mammate mouse Praomys (Mastomys) natalensis develops a great variety of neoplastic and non-neoplastic lesions. Among the non-neoplastic lesions, renal lesions are predominant. From light microscopic, electron microscopic, and immunofluorescence studies, Mastomys glomerulopathy appeared to be comparable to the immune complex glomerulonephritis in several mouse strains. Oncornaviral antigens are demonstrated in these immune complexes in AKR and NZB mice. Therefore, renal tissues of aged Mastomys were screened by the immunofluorescence technique for the presence of oncornaviral antigens by using polyvalent antisera against murine and feline leukemia viruses. Viral antigens were detectable in glomeruli of aged mastomys, but not in kidneys of young mastomys. Infectious virus could be demonstrated in cell-free spleen extracts of three Mastomys. This virus does not grow in Mastomys or mouse embryonic fibroblasts but replicates in the murine BALB 3T3 cell line.

Praomys (Mastomys) natalensis develops a wide variety of autoantibody specificities with age; of these only those to thyroid colloid were associated with a histopathological lesion e.g. thyroiditis. An inverse relationship was found between the mean number of autoantibodies and the occurrence of lymphoreticular tumors. It appears that Mastomys is a better model for studies on the general mechanisms of autoimmunity than for investigating specific autoimmune diseases per se.

The occurrence of lymphoplasmacellular thyroiditis associated with the presence of autoantibodies to thyroid colloid in Mastomys makes it likely that there is an autoimmune thyroiditis in this animal species. Thyroiditis occurred in 16% of the males and in 23% of the females. From longitudinal studies performed in a number of the animals, it appeared that the autoantibodies occurred from the age of 13 months onward and that they persisted until the death of the animals in the majority of the cases. The serum concentration of antibodies to thyroid colloid in Mastomys correlated only roughly with the extent of thyroid infiltration. Neither differences in serum thyroxin concentration nor in proliferative thymic lesions were found between animals with and without thyroid disease.

One hundred and thirty-five sera from aged Mastomys were screened for the presence of spontaneously occurring autoantibodies using an indirect immunofluorescence technique. Such antibodies appeared to be relatively frequent and a number of different tissue specificities were observed. Autoantibodies observed were antibodies to cytoplasmic antigens in liver cells, thyroid follicular cells, and renal proximal tubular cells, striated and smooth muscle, gastric parietal cells, nuclear factors, colloid, and erythrocytes. Several antibody specificities were present in most sera, with a maximum of six and a median value of three different specificities per Mastomys. Anti-striational antibodies of the myasthenic type and anti-colloid antibodies belonged to the IgG class, antierythrocyte antibodies to the IgG and IgM classes, and the other types to the IgM class. From preliminary histopathological data it appears that of the spectrum of autoantibodies present in Mastomys, only autoantibodies directed to colloid could be associated with distinct histopathological changes (i.e., lymphoplasmacellular thyroiditis). Although striational antibodies as found in patients with myasthenia gravis were common in Mastomys, clinical signs of increased muscular weakness were lacking and antibodies to acetylcholine receptors were absent. The multiplicity of autoantibodies in this species together with other abnormalities in the immune system make Mastomys a promising model for the study of basic mechanisms underlying autoimmunity.

The incidence of spontaneously occurring tumors of the cervix and vagina was unusually high in an inbred strain of Brown Norway rats (BN/Bi). Fifty-four tumors were diagnosed in the cervixes or vaginas of 252 rats. Of the tumors, 7 were squamous cell carcinomas, 4 were leiomyomas, and the rest were sarcomas. These tumors were found in nearly 20% of all female rats that died naturally.

Summary The serological and immunochemical properties of antibodies with anti-I specificity found in the serum of a patient with high-titre cold auto-agglutinins are described. Survival studies with 51Cr tagged I and i red cells showed that i cells survived normally and that the I cells had a diminished survival time. The agglutinating and haemolysing antibodies were both β2M globulins. The nature of the positive reaction between the patient's red cells and various anti-human globulin reagents was studied. Anti-C' sera contain at least three different antibodies responsible for the agglutination of cold haemolytic anaemia cells, cells sensitized by naturally occurring incomplete cold antibodies and cells sensitized by Lewis antibodies. Resume Les proprietes serologiques et immunochimiques des anticorps de specificite anti-I trouves chez un patient presentant un titre eleve d'auto-agglutinines du type froid sont discutees. Les etudes de survie d'erythrocytes I et i marques au 51Cr ont demontre que les erythrocytes i survivaient normalement, tandis que les erythrocytes I avaient un temps de survie diminue, Les anticorps hemolysants et agglutinarits etaient tous deux des globulines β2M. La nature de la reaction positive entre les erythrocytes du patient et differents reactifs antiglobuline humaine a ete etudiee. Les serums anti-C' contiennent au moins trois anticorps differents respoilsables de l'agglutination des erythrocytes d'anemie hemolytique du type froid, des erythrocytes sensibilises par des anticorps froirls «naturrls» incomplets et des erythrocytes sensibilises par des anticorps anti-Lewis. Zusammenfassung Die serologischen und immunochemischen Eigenschaften der im Serum einer Patientin mit hochtitrigen Kalteautoagglutininen vorhandenen Antikorpern mit Anti-I-Spezifitat werden beschrieben. Die Uberlebenszeitbestimmung mit Cr-51-markierten I- und i-Zellen zeigte, das die letzteren normal uberlebten, wahrend die ersteren eine verkurzte uberlebenszeit aufwiesen. Die agglutinierenden wie auch die hamolysierenden Antikorper erwiesen sieh als β2-M-Globuline. Der Mechanismus der positiven Reaktion der Patientinnenerythrozyten mit verschiedenen Anti-Human-Globulinseren wurde untersucht. Anti-C'-Seren enthalten mindestens drei verschiedene Antikorper, welche bei der Agglutination van Erythrozyten van Patienten mit erworbener hamolytischer Anamie vom Kaltetypus beteiligt sind, Erythrozyten mit naturlichen inkompletten Kalteantikorpern sensibilisiert sowie Lewis-antikorpersensibilisierte Zellen.

IN several animal species, C-type oncogenic RNA viruses (oncornaviruses) cause malignant tumours of mesodermal origin, such as leukaemia, lymphomas and different kinds of sarcoma1. C-type oncornaviruses have rarely been observed in human mesenchymal neoplasms using electron microscopy2,3, but it has been claimed that molecular-biological methods can demonstrate in the tumours the presence of entities, the nucleic acids of which have sequences in common with the genomes of known mammalian oncornaviruses4–7. There have also been claims that C-type viruses can be detected in tissue cultures of human tumours8–10, although it seems that a contamination with an animal virus had occurred in these cases. Recently11 an agent with type C RNA tumour virus characteristics has been isolated from cultured human acute myelogenous leukaemia cells.

An attempt is made to relate the presence of autoantibodies to pathological changes in aged Mastomys. It appeared that a direct relationship between one of the thymic changes (atrophy, hyperplasia, or neoplasia) and autoantibody formation was doubtful. An association was found between autoantibodies and tumors involving the lymphoreticular tissues (excluding the thymus). Animals in which the lymphoreticular tissues were entirely replaced by tumor cells did not have autoantibodies. For the other lesions, which included thyroiditis, myositis, myocarditis, immune complex glomerulonephritis, and vascular lesions, a direct relationship was found only between thyroiditis and autoantibodies to colloid. The conclusion is that Mastomys seems to be more suited as for studying general phenomena underlying autoimmunity than for studying specific autoimmune diseases.

Conditioning protocols were tested for their efficacy in increasing the incidence of engraftment of histoincompatible dog bone marrow cells. Cyclophosphamide and total body irradation (TBI), Corynebacterium parvum and TBI, a 3- or 5-day delayed transfusion of bone marrow cells after TBI, or an increase in the number of donor bone marrow cells or lymphocytes appeared to be ineffective. These protocols were previously reported to promote recovery of splenic hemopoiesis in mice in short-term assays. The noted discrepancy between studies with mice and dogs invalidated allogeneic resistance as measured in the mouse spleen assay as a model for bone marrow allograft rejection. Intravenous treatment with silica particles or L-asparaginase did improve the engraftment rate after 7.5 Gy TBI. Low efficiency and significant extra toxicity restrict the applicability of these procedures. The most promising conditioning schedule found appeared to be two fractions of 6.0 Gy TBI separated by a 72-hr interval. Prolonged survival was noted after transplantation of bone marrow cells from a one-DLA haplo-type-mismatched donor. Possibilities for further improvement of this protocol are discussed.

Sendai virus infected a hysterectomy derived, barrier maintained breeding colony and a conventional aging rat colony. The virus produced seroconversion in the colonies followed by a 7-month period of decreasing titers. Clinical signs were absent during the months when titers were highest, and there was no increase in mortality, but multifocal interstitial pneumonia with perivascular and peribronchial cuffing by lymphocytes and plasma cells was present in rat lungs examined histologically. Such lesions were absent before the period of seroconversion. During the months of declining titers, the interstitial and perivascular lesions decreased in frequency and severity. The peribronchial lesions did not decrease, however, and were still present in many rats 7 months after the acute infection. Attempts to isolate the virus from weanling rats were unsuccessful.

A mixture of OKT4+4A monoclonal antibodies (reactive with T4 cells) was tested for its immunosuppressive potential in rhesus monkeys receiving a kidney allograft. The kidney transplant model used in this study was designed to mimic the clinical situation. Therefore, all animals received a low dose of azathioprine and prednisolone, and the effectiveness of monoclonal antibody treatment was assessed in nontransfused and transfused recipients. The treatment very effectively suppressed acute graft rejection in untransfused recipients. In transfused recipients, which show an improved graft survival, no additional favorable effect of OKT4 + 4A treatment was seen when this treatment was given at the time of transplantation. It is possible that transfused recipients that reject their kidney in an acute fashion do not benefit from the OKT4 + 4A treatment because they have generated primed effector cells that belong to a T4-negative subpopulation or a T4-positive subpopulation with high affinity for donor cells. When the OKT4 + 4A treatment was given at the time of graft rejection in transfused recipients, thus treating chronic rather than acute rejection, a modest improvement in graft survival was observed. It seems, therefore, that anti-T4 antibodies will be of limited value for clinical transplantation and should be used in combination with other immunosuppressive drugs.

The role of H-2 genetic factors in the development of benign monoclonal gammopathy (BMG) was investigated in six H-2 congenic C57BL and BALB strains (C57BL/10.ScSn and BALB.B: H-2b; B10.D2 and BALB/c: H-2d; B10.BR and BALB.K: H-2k) during ageing. The frequencies of homogeneous immunoglobulins (H-Ig), both single and multiple, in the three C57BL strains were higher than those in the corresponding three BALB strains. No relationship was found with a particular H-2 haplotype. The most frequent H-Ig isotype within the C57BL strains was IgG2a, within BALB.B and BALB.K mice IgG3 and in BALB/c mice IgG1. Categorization of the monoclonal gammopathies (MG) on the basis of their origin showed a single transient monoclonal B-cell proliferation in 2-5% and 3-9% of the C57BL and BALB mice positive for H-Ig, respectively. Multiple myeloma or B-cell lymphoma were found to be responsible for about 1% of the paraproteinaemias in all strains. Persistent, non-progressive MG, most likely BMG, was detected in 70-81% and 39-46% of the C57BL and BALB mice positive for H-Ig, respectively. The remaining 14-24% and 50-58% of the, respectively, C57BL and BALB mice positive for H-Ig could not be evaluated in time. The H-2 haplotypes under investigation were not associated with the onset, occurrence, multiplicity, persistence or isotype of the MG developing in these H-2 congenic C57BL and BALB strains during ageing.

Discontinuous albumin density gradients were used to obtain enrichment of hemopoietic stem cells and depletion of T lymphocytes in aspirated dog bone marrow. Colony forming units in agar (CFU-C) were determined to evaluate the degree of enrichment achieved. An average CFU-C concentration factor of 12.4 was obtained. All transplantations in the study were carried out between DLA-identical sibling combinations. The number of CFU-C administered varied from 0.2 to 5.5 X 10(5)/kg and the number of nucleated cells transfused varied from 0.1 to 1.0 X 10(8)/kg. Stem cell concentrates were found more difficult to engraft than unmodified bone marrow following standard conditioning with a single total-body irradiation (TBI) dose of 7.5 Gy. The efficacy of different TBI-fractionation schedules for obtaining sustained engraftment of CFU-C-enriched grafts in identical bone marrow transplantation (BMT) was determined. A total dose of 12 Gy TBI delivered in two equal fractions of 6.0 Gy (72-hr interval) resulted in sustained engraftment of stem cell grafts in 7 of 7 evaluable dogs. A TBI dose of 9 Gy in two fractions of 4.5 Gy (72-hr interval) resulted in sustained engraftment in 5 of 7 evaluable dogs. The two dogs with engraftment failure received low total cell numbers (10(7) cells/kg) and low CFU-C numbers. 9 Gy of TBI in two fractions of 4.5 Gy (24-hr interval) resulted in sustained engraftment in 11 of 12 evaluable dogs. A significant improvement of engraftment was obtained by increasing the total dose of TBI, which necessitates fractionation into two fractions of TBI. The lower-total-dose TBI (9 Gy) produced less early and late toxicity than the total high-dose (12 Gy) TBI. The incidence of engraftment was similar for the two dosages, however the recovery of peripheral leukocyte counts was slower after 9 Gy TBI. In the dog, optimal conditioning for lymphocyte-depleted hemopoietic stem cell grafts can be obtained by increasing the dose of TBI and concomitant fractionation.

Transplantation experiments in the C57BL/KaLwRij mouse model of idiopathic paraproteinemia (IP) showed that an IP-producing clone can be further propagated in young, lethally irradiated mice and also equally as well in nonirradiated recipients by a bone marrow and/or spleen cell transfer. The latency period before the original paraprotein was detected in the sera of recipients varied in different experiments between 1 and 9 months after transplantation. With subsequent transplantations, the "take" frequency gradually decreased. Propagation of IP for three to four generations seems to be the final limit. In comparison to age-matched seems to be the final limit. In comparison to age-matched control groups, no substantial influence of the transplanted IP on the survival of the recipients was observed. In contrast, transplantation of cells from mice with a B cell lymphoma or a myeloma led to continuous propagation of the malignancy, with a high "take" frequency, progressive development of the paraproteinemia, and a shortened survival time of the recipients. These findings indicate that IP represents in its final stage in the aging C57BL mice an intrinsic cellular defect within the affected B cell clone, which is, however, different from that found in B cell malignancies.

Neuropathies associated with monoclonal gammopathy (MG) in humans have been extensively studied in the past few years, but experimental models have proved difficult to create. C57BL mice are prone to develop benign MG and it has been reported that some of these mice with benign IgG MG present an inflammatory demyelinating neuropathy (IDN). In order to verify such findings, the serum and the sciatic nerve of the first group of 28 C57BL/KaLwRij mice were examined: none of 10 mice with normal serum showed ultrastructural abnormalities in the sciatic nerve, while lesions of IDN were present in three out of 10 mice with benign IgG MD, in two out of seven with benign IgM MG, and in a mouse with Waldenstrom-like lymphoma. The second group of animals was studied in the same way; it was composed of seven C57BL mice with transplanted multiple myeloma, and six C57BL mice with Morbus Waldenstrom-like lymphoma. In none of these animals, which were younger than those of the first group, was any lesion of IDN observed.

An acute Sendai virus epizootic occurred simultaneously in a breeding colony, in experimental and stock animal rooms, and in a colony of aging mice. During the 2-month period that the infection was at its maximum, death rates were approximately doubled. In some strains, the preweanling death rate reached 100%. RFM and BALB/c mice were most susceptible and NZB mice least susceptible. The mortality during the period of Sendai virus infection was increased for most strains and age groups except for the oldest female RFM and NZB mice. Death rates during the epizootic were lowest in young adult mice (greater than 10 weeks of age) and highest in the very young mice (less than 10 weeks of age) and in the oldest male and the moderately aged female mice. Although a substantial number of older mice died during the epizootic, examination of the age-specific death rates indicated that the increase in deaths remained relatively constant for all ages over 10 weeks. This showed that the older mice were not more susceptible to Sendai virus infection. As a sequela of the epizootic, focal chronic pneumonia was found in 10-40% of the mice coming to necropsy even 1 year later.

Resistance to allogeneic bone-marrow grafts (AR) was found to occur in many species, including the dog. The i.v. administration of silica particles suppressed AR in vivo in this species. Genetic studies provide suggestive evidence for the existence of a previously unrecognized system or systems in the canine major histocompatibility complex controlling AR.

Although earlier reports in the literature suggested degenerative changes in the senescent hypothalamo-neurohypophyseal system (HNS), recent investigation showed hyperactivity of this system in the old Wistar (WAG/Rij) rat. In the brain, changes were found in those sites of extrahypothalamic vasopressin (VP) fiber termination that are testosterone-dependent. In the present study, further evaluation of these changes was performed in male Brown-Norway (BN/BiRij) rats. Immunocytochemical staining of VP binding sites in renal tubuli of the senescent, 33-month-old rats was occasional, and could only slightly be enhanced up to weak staining by in vitro preincubation with the peptide, in contrast to the intense staining observed in young, 3-month-old rats. Although VP plasma levels of young and old rats did not differ significantly and no change in either urine or plasma osmolality was observed, urinary VP concentration and 24-hour urinary VP excretion were significantly increased in senescent rats. The activation of the hypothalamo-neurohypophyseal system (HNS) in the senescent rat seems thus to compensate for a decreased responsiveness to VP in the aged kidney. Testicular weight in the senescent animals declined by 40% and a highly significant decrease of 80-90% was observed in total and free testosterone plasma levels. Consequently, changes in peripheral organs in senescent rats may well underly the changes observed in the brain of these animals.

The effects of the treatment of multiple myeloma (MM) with APD-bisphosphonate on bone destruction, the dissemination pattern of the MM, and toxicity for normal and malignant cells were investigated in an animal model, the 5T2 MM. This mouse MM very closely resembles the human disease, including the typical bone lesions. It was demonstrated by radiography, microradiography, and histologic investigation that the treatment of the 5T2 MM with APD-bisphosphonate protected the mice against a loss of bone to a significant extent. It seemed that the treatment with APD not only diminished the bone destruction by the MM but also led to the formation of new bone in already-affected bone tissue. The growth pattern of the MM was not substantially influenced by the treatment, even though there was an indication that APD exerts some cytotoxic effect on the MM cells.

A feeder layer culture system suited to grow carcinoma cells derived from solid human lung tumors was developed. This report deals with culturing of the four main histological types of lung carcinomas observed in 37 patients: 19 squamous cell, 6 adenocarcinomas, 7 small cell, and 5 large cell carcinomas. The cultures were initiated from 24 fresh human surgical specimens and from 14 human lung tumors grown as xenografts in nude mice. Three different patterns of behavior in culture were found to be characteristic for squamous cell, adenocarcinomas, and small cell carcinomas, respectively. The culture pattern presented by the primary cultures did not appreciably change after passaging in vitro for periods of up to 2 years, even after infinite cell lines were established. Cultures of large cell carcinoma showed one or more of these patterns. From these patterns cells could be cloned and subsequently cultured as separate stable lines. The system described facilitates the identification of specific types of human lung carcinomas almost immediately (within 1 h) after plating (Phase I) as well as during culture.

Hydrogel was used to provide water in a solid state to rats and mice under laboratory conditions. Hydrogel was easy to handle and readily consumed by the animals. In studies extending over 10 months, no adverse effects on the condition of the animals were observed. Consumption of hydrogel as the sole source of water for nearly 2 months had no effect on the concentration of selected fecal aerobic microorganisms. Histopathological changes were not observed in the tissues of rats and mice kept for periods up to 7 months on hydrogel as the sole source of fluids. The survival time of rats and mice kept on hydrogel after exposure to supralethal doses of total body irradiation did not differ significantly from that of control animals given drinking water in bottles.

A naturally occurring, chronic disease of the respiratory tract was investigated from the time of its onset to completion of life-time studies in a colony of rats. The disease was characterized by peribronchial lymphoid cuffing, suppurative bronchitis, bronchiectasis and bronchial abscesses. Its onset in the colony occurred a few months after an epizootic of Sendai virus infection. Limited retrospective serological testing indicated that Mycoplasma pulmonis may have been present in the colony at that time and continued to persist throughout life in some rats in the colony. Although of uncertain significance, light and electron microscopy consistently demonstrated many filamentous bacteria between the cilia on respiratory epithelium and free in bronchial exudate in these cases. Attempts to culture this organism on artificial media were unsuccessful.

Five squamous cell carcinomas were induced in the lungs of WAG/Rij rats by radiation emitted from isotopes iridium-192 or iodine-125. Tumor fragments were transplanted subcutaneously in syngeneic hosts for propagation of the tumors. A lung cancer model based on implantation of tumor fragments in the lung has been developed. Tumor implants in the lung grew into large invasive squamous cell carcinomas. Metastases in the renal cortex were frequently observed. Tumor growth was determined from repeated chest radiographs. Volume changes after cytostatic treatment could be monitored accurately up to several months. Squamous cell carcinomas transplanted subcutaneously responded as heterogeneously to a variety of cytostatic drugs as did their human counterparts. Responses of the tumor line L17 to doxorubicin were similar when tumors were growing intrapulmonarily or subcutaneously. However, the response of L33 tumors to cisplatin was different, depending on the location. The tumors growing in the lungs provide a model for realistic testing of regimens involving radiation doses, cytostatic drugs, and combinations thereof.

Squamous cell carcinomas were induced in the lungs of male WAG/Rij inbred rats by radiation emitted from the isotopes iridium-192 or iodine-125. These isotopes were implanted by a surgical procedure in the lungs of young rats. Forty rats received implants of 192Ir wires and 20 animals, of 125I seeds. In a 14-month observation period, 30 of the 40 animals with implants of 192Ir wires developed tumors. Malignant hemangioendotheliomas occurred with the highest frequency (50%). From the lungs of 12 rats, squamous cell carcinomas were found. In the observation period of 17 months, 3 rats with implants of 125I seeds developed tumors, among which 1 squamous cell carcinoma could be identified. Tumor fragments were transplanted in syngeneic hosts for propagation of the tumors. Histologic appearances of tumors remained constant in subsequent passages. Responses of transplanted tumors growing in the flanks of syngeneic hosts to doses of radiation, methotrexate, or vinblastine were determined. Although the histologic appearances of the 5 squamous cell carcinomas were similar, tumor-doubling times and responses to irradiation and chemotherapeutic drugs were different. Small cell or large cell carcinomas were not observed.

Procedures for total and selective gastrointestinal decontamination of dogs are described. The selective procedure removed only Gram negative aerobic bacteria, yeast and fungi. Dogs receiving total decontamination were less susceptible to the GI syndrome following total body irradiation (TBI) than dogs receiving conventional care. After TBI and allogeneic bone marrow transplantation, serum albumin levels decreased in conventional animals, but remained normal in totally or selectively decontaminated animals. Exogenous infections occurred frequently in both irradiated, and totally decontaminated animals, but were absent in selectively decontaminated animals. Endogenous infections after total body irradiation were prevented only by total decontamination. Endogenous infections occurred in selectively decontaminated animals, but with milder clinical symptoms than in conventional animals. Appearance of donor type leukocytes and serum gamma globulin was slower in decontaminated animals than in conventionally treated controls. Acute graft versus host disease caused by a limited number of lymphocytes of a DLA identical littermate donor were prevented by selective gastrointestinal decontamination. Complications due to late immune reconstitution obscured the effect of decontamination on delayed graft versus host disease.

Primary Rauscher leukemia virus (RLV)-induced myeloid leukemias can produce many small clones in agar in the absence of a factor needed for the proliferation of normal myeloid cells. It seems that leukemic cells can more efficiently utilize the small amount of colony-stimulating factor (CSF) that is produced by them. At optimal stimulation by exogenous CSF, leukemic cells exhibit a poorer rate of proliferation than normal bone marrow cells. Hemopoietic cells can replicate the virus after infection in vitro. In some experiments, infection of normal bone marrow cells leads to the production of some cells with the same growth pattern as cells from primary leukemias.

Concanavalin A (Con A) and phytohemagglutinin (PHA) responses of spleen and blood lymphocytes from tumor-bearing (TB) rats were found to be markedly depressed in 4 different models employing tumors of spontaneous origin. Removal of phagocytic cells from both spleen and blood lymphocyte suspensions led to a complete restoration of the responses, indicating that the decreased responses were not due to intrinsic defects in the lymphocytes. The reduction was shown to be due to the inhibitory effect of an increase in the percentage of phagocytic cells. In addition, TB induced an atrophy of the thymus and a decrease in the number of thymic lymphocytes, mainly due to severe lymphocyte depletion in the cortex. The cells that remained in the thymus exhibited increased responsiveness to PHA and Con A as compared to thymus cells from normal rats. Similar results were found in hydrocortisone acetate-treated rats, suggesting that TB leads to a decrease in nonresponsive, cortical corticosteroid-sensitive thymocytes.