The morphology of alveolar tissue destruction

Destruction of intra-alveolar stroma in regions of tuberculous pneumonia is described. This destruction is associated with phagocytosis of argentophilic granules and fibre fragments by macrophages. The specific features of stromal destruction consist of sequestration, fragmentation, lysis, and other, less obvious, changes in reticulin and collagen fibres found in the air spaces. These findings have important implications in chronic fibrosing pneumonitis where similar intra-alveolar stromal changes occur. Destructive stromal changes have also been noted within granulomatous nodules of sarcoidosis in the region of giant cells. Some of the latter also contain argentophilic fibre fragments.

[Is separation of sternopagus conjoined twins possible? (author's transl)]

One case is reported of female sternopagus conjoined twins. One appeared normal, the other presented spina bifida with hydrocephalus. Separation was not made. Embryological study and postmorten findings demonstrate the actual impossibility of separation of sternopagus conjoined twins.

The biologic response to titanium phosphate. A new synthetic mineral fiber

Titanium phosphate, a new manmade fiber, was evaluated by intratracheal and intraperitoneal techniques in rats and hamsters to assess the fibrogenic potential and possible hazard to man. Titanium phosphate fibers structurally resemble asbestos insofar as they are composed of bundles of submicronic fibers. A slight, dose-related fibrogenic response to the fiber was observed subsequent to the intratracheal injection of a 50- and 10-mg/kg but not 2-mg/kg dose in rats or any of these three doses in the hamster. Intraperitoneal administration of 10 or 2 mg/kg of the fibers in rats or hamsters induced no abdominal tumors considered related to treatment. In contrast, approximately 34% of rats given an intraperitoneal injection of 2 mg/kg of asbestos developed abdominal tumors; no tumors developed in hamsters injected with asbestos.

Skin lesions in association with beta-hemolytic Streptococcus group B

A full-term male infant delivered by caesarean section following a prolonged rupture of the amniotic membranes of 30 hours' duration manifested peculiar skin lesions at the time of birth consistent with the healing phase of bullous impetigo. He was colonized with beta-hemolytic Streptococcus group B that was also cultured from the mother's cervix. It is possible this infant became infected in utero since the healing stage of the lesions suggest that they were present sometime before birth.

Tissue destruction in chronic pneumonitis

A hitherto unrecognized, but apparently common, feature of chronic pneumonitis is tissue destruction. This feature may be as important as the proliferative component in formation of honeycomb lung. Fifty-two selected cases of active chronic pneumonitis were studied with hematoxylin-eosin stain, followed by bleach and Gordon and Sweets silver stain for reticulin. Thus, exactly the same cells and tissue could be studied with both stains. Pulmonary tissue destruction in regions of active chronic pneumonitis was indicated by (1) the presence of structureless eosinophilic material containing karyolytic nuclear remnants, (2) the presence of fragments of degenerated reticulin fibers within the air spaces, and (3) the phagocytosis of reticulin fiber fragments by macrophages.

The biologic categorization of inhaled fiber glass dust. A critical review of pertinent studies and reports

Data obtained from animal models of fiber glass pneumoconiosis in which the fiber glass dust was inhaled indicate that fiber glass dust is nonfibrogenic and should be classified as a nuisance-type dust. Fiber glass dust, when inhaled even in high concentrations during much of the animal's lifetime, does not stimulate the production of neoplastic tissue. Epidemiologic data and pathologic examination of the lungs of long-term fiber glass workers indicate that fiber glass dust evokes no recognizable anatomic or functional changes. The development of tumors in the chest and abdominal cavities of rats as a result of the implantation of mineral fibers of diverse composition, including glass, has no relevance to man. The implication derived from such experimental results in rats that inhaled glass fibers are potentially carcinogenic for man, is therefore an inappropriate extrapolation of misinterpreted data.

The mineral dust load of human lungs

Studies of the dust content of lungs from non-industrially exposed city dwellers have shown that many people build up during life a total dust load of 2 grammes or more. This dust load may include up to 17 X 10(6) mineral fibres large enough to be visible with the light microscope and 360 X 10(8) fibres visible only by electron-microscopy. All lungs examined contained a small percentage of fibres that appeared structurally similar to chrysotile asbestos. It was found that the total dust content and content of light microscope sized mineral fibres was much lower in a non-industrialised city than in one with a high level of heavy industry, but levels of electron-microscope sized fibres did not differ markedly between the two groups. It would appear that these very small fibres are part of a general mineralogical background rather than resulting from industrial atmospheric pollution. This was further indicated by the fact that many of the dust particles, including large numbers of the fibrous ones proved to be derived from diatom skeletons.