A quantitative evaluation of the development and anatomy of the ovine spleen and the hematology and histopathology of the ovine spleen exposed to hypoxia

The spleen is an important hematological and immunological organ; however, results of studies are not available on the spleen of the sheep. Therefore, this experiment was designed to study the normal development and structure of the sheep spleen and the effect of hypobaric hypoxia on splenic volume and cellular structure, and blood elements. The normal development and microanatomy of the spleen of the sheep were studied in 8-age-groups: prenatal; 1- day; 1-, 3-, and 6-weeks; 4- and 5-months; and 2-years of age. Morphometrical data were gathered and tested by statistical analysis of variance. The effects of exposure to hypoxia for 15 days on the spleen and peripheral blood were evaluated in 4-month-old sheep. The morphology of the spleen and the changes in the peripheral blood after exposure to hypoxia were studied and compared with the spleen of sheep kept at normal atmospheric pressure. The developmental findings in the 8-age-groups were: 1) splenic-weight per body-weight ratio increased from prenatal to 3-weeks of age, then declined; 2) germinal centers were observed after 3-weeks of age; 3) white pulp increased with age and reached its maximum development by 4-months of age; 4) capsule and trabeculae increased in thickness with age; and 5) no megakaryocytes were observed in any age groups. Histological findings in the spleen of hypoxic sheep were: 1) a significant increase in red pulp volume; 2) multiple nuclei in reticular cells; and 3) an increased thickness of the capsule of the spleen. The hematopoietic results after exposure to hypoxia were: 1) a decrease in platelet sizes; 2) an increase in red blood cell numbers and packed cell volumes; and 3) an initial increase followed by a decrease in platelet numbers. The effects of hypoxia on body growth and splenic weight were. 1) decreased body weight and 2) splenic weight. The increase in white pulp compartments reflects an increase in the immunity of the animal until the fourth month of life. Hypoxia studies lead to the conclusion that stem cell competition between the megakaryocytic and erythroid cell lines is responsible for the decrease in platelet numbers

Cadmium and Cadmium/Zinc Ratios and Tobacco-Related Morbidities

Metals are one of five major categories of carcinogenic or toxic constituents in tobacco and tobacco smoke. Cadmium is highly volatile and a higher percentage of the total tobacco cadmium content is efficiently transferred to mainstream tobacco smoke than many other toxic metals in tobacco. Inhaled cadmium bioaccumulates in the lungs and is distributed beyond the lungs to other tissues, with a total body biological half-life of one to two decades. Chronic cadmium exposure through tobacco use elevates blood and urine cadmium concentrations. Cadmium is a carcinogen, and an inducer of proinflammatory immune responses. Elevated exposure to cadmium is associated with reduced pulmonary function, obstructive lung disease, bronchogenic carcinoma, cardiovascular diseases including myocardial infarction, peripheral arterial disease, prostate cancer, cervical cancer, pancreatic cancer, and various oral pathologies. Cadmium and zinc have a toxicologically inverse relationship. Zinc is an essential element and is reportedly antagonistic to some manifestations of cadmium toxicity. This review summarizes associations between blood, urine, and tissue cadmium concentrations with emphasis on cadmium exposure due to tobacco use and several disease states. Available data about zinc and cadmium/zinc ratios and tobacco-related diseases is summarized from studies reporting smoking status. Collectively, data suggest that blood, urine, and tissue cadmium and cadmium/zinc ratios are often significantly different between smokers and nonsmokers and they are also different in smokers for several diseases and cancers. Additional biomonitoring data such as blood or serum and urine zinc and cadmium levels and cadmium/zinc ratios in smokers may provide further insight into the development and progression of diseases of the lung, cardiovascular system, and possibly other organs