Prophylaxis and treatment of experimental lung metastases in mice after treatment with liposome-encapsulated 6-O-stearoyl-N-acetylmuramyl-L-?-aminobutyryl-D-isoglutamine

A new lipophilic muramyl dipeptide analog, 6-O-stearoyl-N-acetylmuramyl-L-alpha-aminobutyryl-D-isoglutamine, when incorporated in liposomes, was effective in both the prevention and eradication of experimental pulmonary metastases in mice. Multilamellar vesicles composed of synthetic phospholipids (phosphatidylglycerol and phosphatidylcholine) containing saturated myristoyl or unsaturated dioleoyl acyl chains were found to potentiate the antimetastatic activity of this glycopeptide. Prophylactic and therapeutic efficacy was observed against the three murine tumors tested: FSa, an immunogenic fibrosarcoma; NFSa, a nonimmunogenic fibrosarcoma; and B16 melanoma. Neither the administration of empty liposomes or free glycopeptide, nor their coadministration, had a significant antimetastatic effect. This approach is promising for the therapy of cancer metastases in humans, particularly in the prevention of metastatic seeding and in the treatment of micrometastases.

Effectiveness of AMSA alone or in combination with radiation on murine fibrosarcoma pulmonary nodules

The cytotoxic effects in vivo of 4'-(9-acridinylamino) methanesulfon-m-anisidide (AMSA), radiation or both modalities in combination on murine fibrosarcoma (FSa) cells grown as pulmonary tumors were determined. Fourteen days following the i.v. injection of viable FSa cells, recipient mice developed between 100 and 150 visible pulmonary nodules. At that time, tumor-bearing animals were exposed to either single or combined modality treatments, as well as single and fractionated dose regimens. Animals were sacrificed 1 hour after the last treatment. Tumor nodules were excised, made into a single cell suspension and separated on the basis of cell size by centrifugal elutriation. Flow microfluorometry (FMF) was used to determine the cell-cycle parameters and the relative synchrony of the separated populations, as well as the percentage contamination by normal diploid cells in each of the tumor cell populations. Known numbers of viable cells from each elutriator fraction were injected into recipient mice to determine their colony-forming efficiency (CFE). Surviving fractions were determined by comparing the CFEs of treated FSa cells from each of the separated elutriator fractions with those of appropriate untreated controls. Following a single i.v. dose of AMSA (30 mg/kg), populations of cells enriched in S phase were the most sensitive. When a single dose of AMSA was combined with a single dose of radiation (100 rad), there was a marked schedule dependence with the more effective sequence, especially if a 12 hour interval was chosen between doses, being AMSA followed by irradiation. No schedule dependence was observed if both modalities were combined and administered under a fractionated protocol of four fractions of AMSA (5 mg/kg per fraction) and four fractions of radiation (300 rad per fraction). Under these conditions the greatest reduction in CFE was in cell subpopulations most enriched in S and G2 + M phase cells.

Effect of tumor type, size, and endpoint on tumor radioprotection by WR-2721

Experiments are reported showing that the degree of tumor radioprotection afforded by WR-2721 varies with the type of tumor and assay endpoint, and that for a given tumor system, microaggregates are protected better than larger cell masses. The tumors used were a methylcholanthrene-induced fibrosarcoma (FSa), and two tumors of spontaneous origin, another fibrosarcoma (NFSa), and a mammary carcinoma (MCa-4), all syngeneic to C3Hf/Kam mice. WR-2721 was given in a dose of 400 mg/kg 30 minutes before irradiation in all experiments. In TCD50 assays, WR-2721 protected 5 mm diameter and impalpable 3 day-old transplants of 5 X 10(5) FSa cells growing in the leg by factors of 1.11 and 1.13, respectively. Using the tumor latency endpoint, 3 day-old s.c. transplants of 10(3) FSa in the abdominal wall were protected by a factor of 1.27, a degree of protection similar to that reported earlier for sterilization of lung micrometastases of the same tumor. MCa-4 tumors growing in the leg were protected better than FSa in TCD50 assays with protection factors of 1.3 for 4 day-old transplants, 1.24 for 5 mm tumors, and 1.23 for 8 mm tumors. MCa-4 tumors recurrent after irradiation as 4 day-old transplants grew more rapidly in mice that had received WR-2721, and this was shown to be most likely due to protection by the drug against expression of the tumor bed effect. Using the lung micrometastases assay, NFSa was protected by a factor of 1.22. This variability in protection with different tumor types, sizes, and assay endpoints is discussed in terms of drug delivery and uptake, and also in relation to the influence of tumor hypoxia on the radioprotective ability of WR-2721.

Survey of radiographic requirements and techniques in United States dental assisting programs, 1982

A survey of dental assisting programs revealed little standardization of student requirements for dental radiography in the United States. Areas for concern were (1) the high proportion of programs in which classmates exposed one another to ionizing radiation for training purposes and (2) the continued use of closed cones in some cases. Preclinical laboratories in radiography were, on average, of considerably longer duration than those previously reported for dental students. Conversely, clinical requirements in intraoral techniques were less for dental assisting students than is the case for dental students. Available methods of reducing patient exposure to ionizing radiation are not being fully implemented.

Characteristics of a high molecular weight extracellular protein of Streptococcus mutans

A high molecular weight protein antigen, designated P1, has been isolated from the culture fluid of chemostat-grown Streptococcus mutans strain Ingbritt and shown to be free of other antigens including glucosyltransferase. Antiserum against the protein was used in rocket immunoelectrophoresis to confirm and extend the previous observation that there were major differences in the amount of the protein produced under different growth conditions. Physico-chemical and serological studies indicated that protein P1 was indistinguishable from antigens B, I/II and IF isolated in other laboratories. Mammalian tissue cross-reactivity of protein P1 was demonstrated by binding of antiserum to P1 to sections of normal rabbit tissues, particularly heart. There was also a statistically significant increase in the number of mononuclear leucocytes in heart tissue of rabbits which had been injected with protein P1, when compared with the levels in control uninjected rabbits; injection with whole cells of S. mutans Ingbritt did not produce this effect.

Studies on the antitumor activities of pyrimidinone-interferon inducers. Part 2. Potentiation of antitumor resistance mechanisms

In continuation of studies on antitumor activities of pyrimidinone interferon inducers, we report here that 2-amino-5-bromo-6-mF-phenyl-4(3H)-pyrimidinone (ABmFPP) is similarly effective to 2-amino-5-bromo-6-phenyl-4-pyrimidinone (ABPP) in its ability to reduce the number of metastatic nodules of a spontaneous fibrosarcoma (NFSa) and a spontaneous mammary carcinoma (MCa-K) in the lungs of C3Hf/Kam mice. Both compounds were more effective when given to mice prior to, rather than after, intravenous transplantation of tumor cells. In studies on the mechanism of the antitumor activity of pyrimidinones, 2-amino-5-iodo-6-phenyl-4-pyrimidinone (AIPP) was used in addition to ABPP and ABmFPP. These agents were capable of activating peritoneal macrophages that thus became capable of lysing in vitro 3T12 transformed cells but not syngeneic BALB/c embryo fibroblasts. Also, these agents were capable of augmenting significantly the natural killer (NK) cell activity in the spleen of C3Hf/Kam mice. Spleen cells from treated mice admixed to NFSa cells inhibited in vivo tumor take of these cells when the admixture was injected subcutaneously. Pyrimidinones were also effective against the development of NFSa nodules in the lungs of T-cell deficient mice implying that the presence of T-cells is not a prerequisite for the induction of antitumor activity by these agents. A further observation was that pyrimidinone compounds reduced the metastasis formation enhancing effect of cyclophosphamide. Therefore, pyrimidinone interferon inducers exhibit an appreciable antimetastatic activity mediated through antitumor resistance mechanisms involving activation of macrophages and stimulation of NK-cells.

Effect of tumor size on S-2-(3-aminopropylamino)ethylphosphorothioic acid and misonidazole alteration of tumor response to cyclophosphamide

The influence of tumor size on the ability of S-2-(3-aminopropylamino)ethylphosphorothioic acid (WR-2721) or misonidazole (MISO) to alter cyclophosphamide (CY) antitumor activity was investigated, using a chemically induced fibrosarcoma (FSA) and a spontaneous fibrosarcoma (NFSA) in C3Hf/Kam mice. Tumors were of two sizes at the time of treatment, 8-mm leg tumors and 4-day-old micrometastases in the lung. The antitumor activity of CY and its modification were assessed by growth delay of leg tumors and the reduction in the number of lung metastases. Both measures of tumor response were more pronounced as the dose of CY increased, and FSA was more sensitive to CY than was NFSA. WR-2721 (400 mg/kg), given 30 min before treatment with CY, reduced the effectiveness of CY on both FSA and NFSA. This reduction in effectiveness of CY was only minimal for leg tumors (dose-modifying factors were 1.1 for FSA and 1.03 for NFSA) but remarkable for lung micrometastases (dose-modifying factors were 1.81 for FSA and 1.55 for NFSA). Protection increased with the increase in the dose of WR-2721 and was also dependent on the time of injection relative to CY. The greatest protection occurred when WR-2721 was given within 30 min before to 15 min after CY. Tumor size had the opposite effect on MISO from that on WR-2721. MISO (1 mg/g) enhanced the effect of CY more effectively for leg tumors than for lung micrometastases: dose-modifying factors were 1.74 for FSA and 2.21 for NFSA growing in the leg and 1.27 for FSA and 1.11 for NFSA lung micrometastases. Therefore, tumor size appears to be a very important factor in determining the extent of WR-2721- and MISO-induced modification of CY antitumor effect.

Protection by S-2-(3-aminopropylamino)ethylphosphorothioic acid against radiation-induced leg contractures in mice

S-2-(3-Aminopropylamino)ethylphosphorothioic acid (WR-2721) was shown to provide marked protection against development of radiation-induced leg contractures in C3Hf/Kam mice whose legs were exposed to single doses of gamma-radiation. The radiation doses ranged from 3300 to 6200 rads delivered to the right hind thighs from two parallelly opposed 137Cs sources. WR-2721 was given i.p. 30 min before irradiation. The severity of radiation-induced leg contractures in untreated and WR-2721-treated mice was followed for 342 days after irradiation. The degree of leg contractures in both control and WR-2721-treated mice increased up to 100 days after radiation, when the change stabilized, remaining more or less at the same level to the end of the observation period. During this entire period, the severity of contractures was less in WR-2721-treated mice. The dose-modifying factor for the level of 5 mm reduction in leg extension was 1.5 at 182 days after irradiation. Since WR-2721 did not prevent the radiocurability of 8-mm fibrosarcomas growing in the same legs, these data imply that WR-2721 has a high potential for increasing therapeutic gain when combined with irradiation in the treatment of tumors of an appreciable size.

Inhibition of artificial and spontaneous lung metastases by preirradiation of abdomen--II. Target organ and mechanism

We have previously reported that irradiation of the abdomen of mice before i.v. injection of both immunogenic and nonimmunogenic tumour cells is capable of suppressing their ability to form metastatic lung nodules in a time and dose-dependent fashion. Experiments with segmental exposure indicated the target organ to be located in the ventral half of the abdomen. The effect has now been shown positively to depend upon irradiation of the caecum, and can be abolished either by shielding the caecum from irradiation or by surgically removing it prior to irradiation. Further experiments have shown that the effect cannot be elicited in germ-free mice and that its magnitude is markedly reduced in animals given gut-sterilizing antibiotics. Split-dose irradiation only slightly reduced the magnitude of suppression, provided both doses were given within the time window of effectiveness of single doses. Tumour-growth retardation was observed and spontaneous lung metastases were also suppressed when tumour-bearing mice received abdominal irradiation 7 days after tumour cell transplantation into the leg. However, abdominal irradiation did not significantly reduce subsequent tumour transplantability by the s.c. or i.p. routes. The experimental data are consistent with a mechanism by which transmigration of enteric bacteria across the radiation-damaged mucous membrane of the caecum effectively results in an endogenous infusion of endotoxin.

Radiosensitivity of irradiated mouse skin to a second course of single and multifractionated irradiation. I. Early skin reaction

Six or 12 months after a single or multifractionated gamma ray irradiation of the skin from the hind legs of mice, the response of the skin to the test dose in single or multi-fractionated (4-16) exposures was studied, using an early skin reaction as an endpoint. The pre-irradiated skin was relatively radioresistant compared to the previously untreated control skin in either dorsal or ventral sides of the legs. The variation in the skin sensitivity depending on the site of irradiation is also discussed for the pretreated and the untreated skin.

Visual cell profiles for quantitation of premalignant cells in sputum: a preliminary report

Visual cell profiles were used to analyze the distribution of atypical bronchial cells in sputum specimens from cigarette-smoking volunteers, cigarette-smoking asbestos workers and cigarette-smoking uranium miners. The preliminary results of these sputum visual cell profile studies have demonstrated distinctive distributions of bronchial cell atypias in progressive patterns of squamous metaplasia, mild, moderate and severe atypias and carcinoma, similar to those the authors have previously reported using cell image analysis techniques to determine an atypia status index (ASI). The information gained from this study will be helpful in further validating this ASI and subsequently achieving the ultimate goal of employing cell image analysis for the rapid and precise identification of premalignant atypias in sputum.

Protective effects of S-2-(3-aminopropylamino)ethylphosphorothioic acid against radiation damage of normal tissues and a fibrosarcoma in mice

S-2-(3-Aminopropylamino)ethylphosphorothioic acid (WR-2721) was investigated for its protective effect against radiation-produced damage of jejunum, testis, lung, hair follicles, and a fibrosarcoma of C3Hf/Kam mice. Most of these tissues were radioprotected, and the degree of radioprotection depended on the dose of WR-2721 and the time interval between administration of WR-2721 and radiation treatment. WR-2721 increased resistance of jejunal epithelial cells and spermatogenic cells to single doses of gamma-rays by factors of 1.64 and 1.54, respectively. Protection against hair loss was less pronounced; the dose-modifying factor here was 1.24. The radiation-induced acute damage of the lung expressed by the increased formation of tumor nodules in the lung was not decreased by treatment of animals with WR-2721 before radiation. In contrast, WR-2721 augmented the radiation-induced enhancement of metastasis formation in the lung. WR-2721 protected fibrosarcoma micrometastases in the lung against therapeutic effect of radiation by a factor of 1.238. In contrast, this compound had no effect on the therapy of an 8-mm fibrosarcoma growing in the legs of mice.

Protective effects of WR-2721 against radiation-induced injury of murine gut, testis, lung, and lung tumor nodules

WR-2721 (S-2-(3 aminopropylamino) ethylphosphorothioic acid) has been investigated for its ability to protect gut, lung, and testis, as well as fibrosarcoma (FSa) tumor nodules, in the lungs of mice from gamma-radiation injury. This compound greatly protected jejunum and testis epithelial cells. FSa micrometastases in the lung were protected to a lesser extent than jejunum and testis. Conversely, WR-2721 was not able to protect the lung against radiation-induced enhancement of tumor metastases formation generated by intravenously injected FSa cells.

Studies on the antitumor activities of pyrimidinone-interferon inducers. I. Effect against artificial and spontaneous lung metastases of murine tumors

Since pyrimidinone compounds induce interferon production in several animal species and have potent antivirus activities, it appeared important to determine whether these compounds could also induce antitumor activities in their recipients. Pyrimidinone compounds 2-amino-5-bromo-6-methyl-4-pyrimidinone (ABMP), 2-amino-5-brome-6-phenyl-4-pyrimidinone (ABPP), and 2-amino-5-iodo-6-phenyl-4-pyrimidinone (AIPP) were studied for their activities against artificial lung metastases of the weakly immunogenic spontaneous fibrosarcoma NFSa, the moderately immunogenic spontaneous mammary carcinoma MCa-K, and the strongly immunogenic 3-methylcholanthrene-induced fibrosarcoma FSa syngeneic to inbred C3Hf/Kam mice. In addition, the therapeutic efficacy of ABPP and AIPP was also determined against spontaneous lung metastases of NFSa. ABPP and AIPP given ip at 250 mg/kg for 2 or 3 consecutive days before or after iv inoculatin of NFSa, FSa, or MCa-K cells greatly reduced the number of tumor nodules developed in the lungs. ABMP, however, was considerably less effective. ABPP and AIPP were also effective in therapy of spontaneous lung metastases of NFSa, especially when these compounds were given before surgical removal of the primary tumor. Neither ABPP nor AIPP was effective against tumor nodules growing in whole-body irradiated (WBI) mice, but both protected mice against enhancement of lung metastasis formation induced by exposure to whole-body irradiation. ABPP was more effective than AIPP in inducing production of interferon in normal mice. When treated with ABPP, WBI mice, however, were unable to produce interferon. These results show that 6-phenyl-pyrimidinone compounds induce strong antitumor activities in mice, which correlated with neither tumor immunogenicity nor the ability of these agents to induce interferon, but which depended on the immune status of the tumor host.

Long-term effects of pulmonary damage in mice on lung weight, compliance, hydroxyproline content and formation of metastases

The development of "metastatic" colonies of fibrosarcoma in the lungs of mice after IV injection of a single-cell suspension of tumour cells varied with time after irradiation or administration of bleomycin. Most notably, there was a late radiation-induced enhancement of colony-forming efficiency that coincided with an increase in lung weight and hydroxyproline content and a decrease in compliance. There was no radiation-induced enhancement of "spontaneous" metastases from a mammary carcinoma implanted in the thighs of the animal. The sequence of events after administration of bleomycin was similar to that after irradiation, but the duration of the treatment was different and the temporal relationship between enhanced colony-forming efficiency and changes in lung weight and hydroxyproline content was not as clear cut.

Therapy of artificial and spontaneous metastases of murine tumors with maleic anhydride-divinyl ether-2

A 15,500 molecular-weight fraction of a pyran copolymer, (MVE-2) was investigated for its therapeutic efficacy against artificial lung metastases of a weakly immunogenic spontaneous fibrosarcoma (NFSa), a relatively strongly immunogenic fibrosarcoma (FSa), a moderately immunogenic spontaneous mammary carcinoma (MCa-K-, and a weakly immunogenic spontaneous mammary carcinoma (MDAH-MCa-4) syngeneic to C3Hf/Kam mice. In addition, the therapeutic efficacy of this polyanionic compound against spontaneous lung metastases of NFSa was also determined. Systemic i.v. or i.p. application of MVE-2 in doses ranging from 10 to 50 mg/kg body weight greatly reduced the number of artificial NFSa lung metastases and prolonged the survival of the mice. Multiple injections of MVE-2 given at weekly intervals were more effective than were single treatments. Although various treatment schedules with MVE-2 were capable of reducing the number of metastases and prolonging survival of tumor-bearing mice, no cures were observed. A therapeutic effect was also evident against spontaneous lung metastases of NFSa. The effect, however, was more profound when MVE-2 was given before rather than after surgical removal of the primary tumor. MVE-2 was not effective in mice exposed previously to whole-body or local thoracic irradiation. In contrast, MVE-2 protected mice against enhancement of lung metastases induced by exposure of the mice to these irradiations. NFSa growing i.m. promoted the formation of lung metastases from tumor cells given i.v. This concomitant enhancement of metastases was abolished by treatment of the mice with MVE-2. MVE-2 was also effective against tumor deposits in the other three tumors. The extent of its therapeutic efficacy was independent of tumor immunogenicity. These results suggest several approaches to the clinical application of MVE-2 and provide additional data on the therapeutic activity of the pyran copolymer derivatives in different animal models.

Antibody response to streptococcal cell wall antigens associated with experimental arthritis in rats

The antibody response to group A streptococcal cell wall components was measured in rats during the development of chronic, remittent experimental arthritis. The arthritis was induced by a single intraperitoneal injection of an aqueous suspension of group A streptococcal cell wall fragments and antibodies were measured by a radioactive antigen-binding assay. Antibodies in serum against both peptidoglycan and A polysaccharide reached maximum levels at 1 or 2 weeks and declined to preimmunization levels by day 63. The kinetics and magnitude of the antibody responses were similar in neonatally thymectomized and non-thymectomized rats. A relationship between chronic joint lesions and anti-peptidoglycan concentration in serum was indicated, since all rats which produced high levels of antibody developed severe chronic arthritis. However, 46% of the rats which produced very low levels of antibody also developed moderate to severe arthritis. There was no correlation between anti-A polysaccharide antibodies and joint disease, although the concentration of this antibody was 10- to 100-fold greater than the anti-peptidoglycan. We conclude that antibody can be a component in the pathogenesis of this experimental model of arthritis, but its role requires further elucidation.

Cell-mediated immune response during experimental arthritis induced in rats with streptococcal cell walls

Chronic, remittent, erosive arthritis was produced in rats by a single intraperitoneal injection of an aqueous suspension of cell wall fragments isolated from group A streptococci. Arthritis could be induced in rats which had been immunologically compromised by neonatal thymectomy. Delayed hypersensitivity to cell wall peptidoglycan could not be elicited in these rats, although progressive joint disease was obvious by clinical and radiological measurements. A delayed skin test was elicited with peptidoglycan in non-thymectomized rats at 6 to 14 days after injection of low doses of cell wall fragments. Between 2 to 4 weeks after cell wall injection the skin test could not be elicited and these rats could not be sensitized again with peptidoglycan. After a high dose of cell wall the skin test could not be elicited at any time. These non-thymectomized rats which had been injected with cell walls remained hyporesponsive to peptidoglycan for at least 3 months. Lymphocytes from non-thymectomized cell wall-injected rats also showed a non-specific depression of lymphocyte response to phytohaemagglutinin in vitro, but this function was recovered between 2 to 4 weeks after cell wall injection. We conclude that cell-mediated immunity against bacterial cell wall antigens is not a pathogenetic factor in this experimental model of arthritis.

Lipopolysaccharide Composition of the Wilt Pathogen, Pseudomonas solanacearum: CORRELATION WITH THE HYPERSENSITIVE RESPONSE IN TOBACCO

In the induction of the hypersensitive response (HR) in tobacco by Pseudomonas solanacearum, the recognition between host and pathogen is thought to involve an interaction between plant lectins and bacterial lipopolysaccharide (LPS). The LPS of a series of strains of P. solanacearum were examined to determine if there are structural differences that might account for the ability or inability of these strains to induce the hypersensitive response. Analysis of the components of LPS by gas chromatography indicates a clear difference in sugar composition between the HR-inducing and non-HR-inducing strains, especially in terms of the percentage of glucose, xylose and rhamnose. Sodium dodecyl sulfate polyacrylamide gel electrophoresis shows there are two distinct kinds of LPS, differing greatly in size, which correspond to rough and smooth LPS in other systems. In addition, a phage, CH154, was isolated which lyses non-HR-inducing bacteria and which is inactivated by LPS from these bacterial strains. Therefore, differences in LPS structure correlate strongly with host recognition of Pseudomonas solanacearum.

Inhibition of artificial lung metastases in mice by pre-irradiation of abdomen

A phenomenon by which pre-irradiation of the abdomen of mice reduced the lung-colony-forming efficiency of i.v.-injected tumour cells is described. The extent of lung-colony inhibition was shown to depend on both the dose and timing of abdominal irradiation. The maximum inhibitory effect was obtained when mice received 1200 rad gamma-irradiation to the abdomen 5--7 days before tumour-cell challenge, but there was no effect when abdominal irradiation was given 1 or greater than or equal to 14 days before challenge, or when radiation doses were less than 600 rad. In mice less than 3 weeks old, the effect was much less marked than in adults. The target tissue which, when irradiated, exerted the inhibitory influence on lung-colony formation was located in the ventral half of the abdomen in all 4 quadrants, and was probably gut. Radioactively labelled tumour cells were arrested normally in the lungs of irradiated mice, but were cleared more rapidly without evidence of sequestration in the irradiated gut. The most plausible mechanism seems to be that irradiation of the gut induces the production of natrual killer cells with anti-tumour activity, though this has not been conclusively established.