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Biomedical subjects

A Richters

Publications and source records attributed to A Richters.

44 records · Page 3Linked to original sources
PubMedDate not supplied

Inhalation of NO2 and blood borne cancer cell spread to the lungs.

An experimental model was designed where the frequency of blood-borne cancer cell metastases to the lungs of animals was used as an indicator to detect adverse effects of inhaled nitrogen dioxide (NO2). Animals were exposed to air containing 0.40 +/- 0.05 ppm or 0.80 +/- 0.05 ppm of NO2. After the appropriate exposure periods, the animals were infused intravenously with B16 mouse melanoma cells. At 3 wk post-infusion the animals were killed and the lungs were examined for melanoma nodule development. The lungs of the NO2-exposed animals contained a significantly higher number of melanoma nodules than the lungs of control animals (P less than .0025). These results indicate that inhalation of ambient or near ambient levels of NO2 influences the metastasis of blood-borne cancer cells. This raises the possibility that similar events may occur in the human population.

Animals↗
PubMedDate not supplied

A new relationship between air pollutant inhalation and cancer.

Many studies have been conducted to investigate the effects of different air pollutants on health. Our studies have focused on the effects of nitrogen dioxide (NO2), and recently we reported that inhalation of low levels of NO2 can facilitate cancer cell metastasis. The study described herein utilized the same B16 mouse melanoma metastasis model of previous investigations, but under different NO2 exposure conditions. The results provide further evidence that inhalation of ambient level NO2 (0.4 ppm) or polluted urban ambient air play a role in facilitation of blood-borne cancer cell metastasis. In addition, results show different patterns of melanoma cell distribution in the lungs of NO2- and ambient-air exposed animals. They also indicate that extended periods of clean air between NO2 exposures may diminish the severity of the insult in the less sensitive animals. It is our conclusion that the results provide strong support for the need of improved air quality and for reduction of noxious pollutants in urban ambient air.

Air Pollutants↗
PubMedDate not supplied

Ambient level ozone effects on subpopulations of thymocytes and spleen T lymphocytes.

The effects of ozone on thymocyte and spleen T lymphocyte subpopulations were studied. Balb/c mice were exposed to clean air or to 0.3 +/- 0.05 ppm ozone for 1-3 wk. Thymocytes and spleen T cells were stained with fluorochrome conjugated monoclonal antibodies against surface differentiation markers and/or propidium iodide for deoxyribonucleic acid (DNA). The cells were then analyzed by fluorescence activated cell sorter. The percentages of certain thymocyte and spleen T lymphocyte subtypes and DNA synthesizing spleen T cells were lower following 1 wk of ozone exposure. After 3 wk exposure, the thymocyte percentages were higher in ozone-exposed mice, whereas the absolute number remained lower, and spleen T lymphocytes showed no changes. The findings suggest that short-term ozone inhalation can affect the T cell immune system adversely, particularly the CD4+ cells.

Animals↗
PubMedDate not supplied

The relationship between inhalation of nitrogen dioxide, the immune system, and progression of a spontaneously occurring lymphoma in AKR mice.

The effects of exposure to an ambient level of nitrogen dioxide (NO2) on the development and progression of the spontaneous T-cell lymphoma in AKR/cum mice are evaluated. The animals were exposed to 0.25 ppm +/- 0.05 ppm NO2 for 7 hr/day, 5 days/week for up to 181 days. Following exposure periods of 37, 71, 111, 141, and 181 days, the extent of lymphoma was determined microscopically in histologic sections of the thymus, spleen, lymph nodes, lung, and liver. In addition, T-lymphocyte subpopulations were quantitated by flow cytometry. The results indicate that the development and progression of lymphoma in mice was influenced by intermittent inhalation of NO2. The lymphoma was detectable earlier in control animals and the survival of the NO2-exposed group was significantly higher. The T-lymphocyte subpopulations were significantly lower in NO2-exposed animals following 37 and 181 days of NO2 exposure. The T-helper/inducer (CD4+) lymphocytes were adversely affected to the greatest extent, explaining in part the more aggressive behavior of the lymphoma in the control animals. Most importantly, these studies provide additional evidence that in vivo exposure to a level of NO2 commonly encountered in polluted metropolitan areas adversely affects cells of the immune system. In the case of the AKR mouse, the adverse effect of NO2 on CD4+ cells manifested itself by retarding development and progression of the spontaneous lymphoma. Our data suggest that this neoplasm may be dependent on growth factors such as interleukin 2, produced by CD4+ lymphocytes in the early stages.

Air Pollutants↗
PubMedDate not supplied

Influence of ambient level NO2 exposure on newborn and adult mice body weights.

A study of the effects of NO2 inhalation on body weights of newborn and adult mice was carried out. A total of 1590 adult mice and 450 newborn mice were evaluated. The level of NO2 exposure was in the ambient range and varied between 0.17 and 0.80 +/- 0.05 ppm depending on experimental design. The duration of exposure was three to twelve weeks, depending upon specific experimental design. The results have indicated that newborn mice are more sensitive than adults to the inhalation of ambient level NO2 and showed significantly lower body weight gains. The findings were interpreted as being indicative of adverse systemic NO2 effects on newborn animals.

Administration, Inhalation↗