Kinetic aspects of Ki-67 antigen expression in a normal cell line.

Using a normal cell line derived from a human fetus, the disappearance and reappearance of the Ki-67-reactive antigen following modification of the cell cycle was observed and estimated immunohistologically. It was found that G1/G0 arrest induced by serum deprivation resulted in loss of the antigen in 24 h in all but a few (usually less than 10%) of cells. Return to normal medium and resumption of growth was accompanied by reappearance in 30 h. When entry into S-phase was prevented by desferrioxamine, reappearance of the antigen still occurred but only lasted for about 24 h. Inhibition of protein synthesis with cycloheximide also caused fading and eventual loss of immunostaining. In view of the ease with which this antigen becomes undetectable with cessation of protein synthesis and interruption of the cell cycle, we agree with those who advise caution in the use of Ki-67 to measure growth fraction in changeable cell populations such as tumours.

Biochemical evidence for an increased and progressive deposition of collagen in lungs of patients with pulmonary fibrosis.

To assess the role of changes in lung collagen in pulmonary fibrosis, the content of this protein was measured in biopsy and autopsy lung from patients with cryptogenic fibrosing alveolitis (CFA), a fibrotic lung disorder of unknown cause. The collagen concentration was measured in lung samples from 21 patients with CFA (14 autopsy and seven open-lung biopsy) and 17 normal subjects; total lung collagen was determined in the right lung of 10 patients who died from CFA and the results were compared with those from 10 normal lungs. There was a wide variation in the collagen concentrations but the mean value (+/- SEM) for patients with CFA (217 +/- 13 mg/g dry weight) was significantly higher (P less than 0.02) than that of the controls (155 +/- 15 mg/g dry weight). The mean collagen concentration of the autopsy samples (243 +/- 20 mg/g dry weight) was significantly higher (P less than 0.05) than that of the biopsy samples (165 +/- 24 mg/g dry weight). The mean total collagen was markedly raised (P less than 0.001) in right lungs of patients with CFA (32.5 +/- 4.3 g) compared with normal lungs (14.0 +/- 1.1 g). When corrected for the predicted lung volume this difference in total lung collagen remained statistically significant (P less than 0.01, mean for patients 4.7 +/- 0.7 mg/ml, controls 2.3 +/- 0.2 mg/ml). These results demonstrate an increased deposition of lung collagen in this form of pulmonary fibrosis. They also suggest that there is a greater collagen concentration in lungs of patients with later disease, indicating a progressive deposition of collagen during the course of the disease.

Bone changes in mice after prolonged continuous exposure to a high concentration of carbon monoxide.

Quantitative and qualitative pathological changes in mouse bones are described after continuous exposure to 0.24% v/v of carbon monoxide in air for periods of up to 180 days. Planimetric measurements of five bones (parietal bone, sternum, lumbar vertebrae, ribs and shafts of femurs) showed a considerable increase in the amount of bone tissue in all bones except the femurs. The greatest amount of new bone formation was found, in decreasing order, in the skull, ribs, lumbar vertebrae and sternal segments. The cortex of the femur shafts showed some thinning, although there was more trabecular bone in the metaphyses. At the same time an expansion of marrow cavities was found in ribs, parietal bones and femurs. Possible pathomechanisms responsible for the excessive bone formation are explored. It is suggested that an increased rate of blood flow through the bone and marrow tissues played an important role.

Effects of environmental temperature on haemopoietic stem cells in the tails of mice.

Using the endogenous spleen colony assay method of Till & McCulloch (1963), the numbers of haemopoietic stem cells present in the bone marrow in the tails of mice were estimated under different environmental temperatures. Compared to animals kept at 22--26 degrees C, mice transferred to an kept at 36.5 degrees C showed a doubling of colony-forming units in the tail in 1--4 weeks. Exposing them to 8 degrees C caused a significant depopulation to approximately one-third in 3--4 weeks. By transferring the mice from one temperature extreme to another these changes could be reversed. Tail marrow depleted of viable stem cells by X-irradiation was repopulated within approximately 3 weeks in animals kept at room temperature or above but this process was inhibited in the cold.

Adaptation of mice to carbon monoxide and the effect of splenectomy.

The adaptation of normal and splenectomized mice to increasing concentrations of carbon monoxide (CO) in air, and their subsequent long-term survival in it were studied. From the 10th day onwards the concentration of CO was maintained at 0.24%, which produced a carboxyhaemoglobin level of about 74% in the blood, and which was normally lethal within 24 h. However, the non-splenectomized mice survived in this envirment for an average of 47 days, but splenectomized moce survived for 101 days. During adaptation to CO there were marked increases in the haematocrit level and the concentration haemoglobin, a massive release of reticulocytes into the circulation, and increases in blood volume, spleen and heart weight. However, changes in the above haematological parameters were significantly less in splenectomized than in normal animals. These differences were attributed to the loss of the erythropoietic reservees of the spleen. In splenctomized mice which survived for over 90 days in CO there was histological evidence for the development of extramedullary erythropoiesis, as well as increased erythropoietic activity in the marrow of the tail vertebrae, which occurred earlier. Deaths were most frequently associated with massive internal haemorrhages in both groups of animals. This is discussed in relations to histological and haematological findings. Also in both groups, there was evidence that both hypertrophy and hyperplasia of heart muscle fibres occurred during adaptation to breathing CO.