Histochemical and ultrastructural study of lactic dehydrogenase in chemically induced lung cancer.

Light and electron microscopy studies of lactic dehydrogenase activity were carried out in embryonic, neonatal, and adult mouse lungs and in lungs undergoing chemically induced carcinogenesis. Embryonic mouse lungs were collected on the 6th, 12th, and 18th days of gestation; 1-day-old lungs were used for the neonatal model. These were compared with adult normal mouse lung and lungs of the animals treated with 4-nitroquinoline 1-oxide at a monthly interval until cancer developed. Enzymatic activity was seen in the embryonic, precancerous, and malignant lung tissues and was found diffusely in the cytoplasm of the epithelial cells.

Suggestive evidence for a direct innervation of mucosal mast cells.

Mast cells are often observed near nerves and functional evidence suggests an innervation of these cells. In the present ultrastructural study, nerve terminals containing many small clear vesicles and a few large vesicles with dense matrix were observed in direct contact with the plasma membrane of mucosal mast cells in the rat ileum, strongly suggestive of a direct innervation.

Inhibition of afferent vagus nerves decreases gastric stress lesions.

Capsaicin (Sigma Chemical Co.) is a unique chemical agent that causes degeneration of afferent nerve fibers. Previous conclusions about Capsaicin effects on the gastric mucosal response to stress have not precisely defined which afferent nerves were affected. Therefore, the aim of the first portion of this study was to define the origin of afferent vagus nerves to the anterior gastric wall after injections of fluorogold (which is an axonal tracer) into the stomach. The second part of this study was to compare the stress effects on the gastric mucosa in rats with impaired afferent nerve function after Capsaicin treatment.

The normal electron histochemistry and the effect of hemorrhagic shock on the pulmonary surfactant system.

An electron histochemical study was carried out on eight baboons to localize the phospholipid constituent of pulmonary surfactant in the normal state and after hemorrhagic shock. In the normal state, phospholipid was seen as a continuous layer lining the alveolar spaces. Phospholipid also was seen in the inclusion bodies of the granular pneumocytes, suggesting these cells as the site of production of surfactant. After hemorrhagic shock, the previously continuous phospholipid layer lining the alveolar spaces became totally fragmented. In addition, increased numbers of phospholipid particles were seen within the pulmonary interstitium. The results of this study suggest that the pulmonary surfactant system may be impaired after hemorrhagic shock.

Ultrastructural observations in the rat ileal mucosa of possible epithelial "taste cells" and submucosal sensory neurons.

Electronmicroscopical studies of the rat ileum have demonstrated the presence of submucosal neuronlike cells located just under the basal lamina of intestinal crypts. These cells had dendrite-like processes and frequently made contacts with adjacent submucosal nerve terminals. Furthermore, within the mucosa epithelial "clear' cells with apical cytoplasmic processes into the gut lumen and basal cytoplasmic processes extending underneath adjacent epithelial cells were demonstrated. The "clear' cells were devoid of secretory granules, as e.g. endocrine cells, and had a morphological resemblance to taste cells. Occasionally the "clear' cells made contacts with submucosal nerve terminals. The possibility that the "clear' cells and submucosal neuronlike cells represent a receptive function within the intestine is discussed.

Further evidence for the presence of subepithelial nerve cells in the rat ileum--an immunohistochemical study.

Earlier we observed electronmicroscopically an unidentified but neuron-like subepithelial cell in the crypts of the rat ileum. We have now studied some immunocytochemical characteristics of similar cells in the fluorescence microscope by indirect immunofluorescence. Three markers for neuronal tissues were used: 1) Monoclonal Thy-1-antibodies, demonstrated previously to recognize surface antigens of thymus-derived cells and nervous tissue; 2) Tetanus toxin, which binds to the GT1 ganglioside receptor of nerve cells, and to some other neuronal receptor; and 3) Anti-Protein I-IgG, which is monospecific for Protein I located in synaptic vesicle membranes. The various antisera used for secondary incubations all reacted with leucocytes and other connective tissue cells in the villous cores. When the specific primary antisera of Thy-1 and Protein I, and tetanus toxin, were included, a small number of spindle-shaped cells with two processes, extending just beneath the basal lamina of the epithelium, was observed. These cells had a similar location and appearance as the neuron-like cells observed electronmicroscopically and may be identical with these cells. These results give further evidence that cells with neuron-like characteristics are present in the mucous layer of the small intestine.

On the presence of serotonin in the gut lumen and possible release mechanisms.

The possible presence of a luminal release of serotonin (5-HT) from gut enterochromaffin cells (EC) of the rat, was studied after the injection of the tritiated 5-HT precursor 5-hydroxytryptophan (3H]-5-HTP by electron microscopic autoradiography. The uptake of 5-HTP into gut epithelial cells was also studied by fluorescence histochemistry according to the Hillarp-Falck technique at the same post-injection interval as in the autoradiography experiments. 3 h after the injections of 5-HTP (100 mg/kg i.v.) the fluorescence intensity of EC was increased and numerous, probably enteroendocrine, cells had an increased yellow tryptamine induced fluorescence due to an uptake of 5-HTP and probably decarboxylation to 5-HT. However, the labelled precursor [3H]-5-HTP was taken up not only into granules of enteroendocrine cells but also incorporated into the cytoplasm and nucleus of nonendocrine cells when studied by autoradiography. After 10 min of efferent electrical stimulation of the vagal nerve much of the label was found in the gut lumen suggesting a release of the amine. The hypothesis of a luminal release of 5-HT was further corroborated in starved cats, where considerable amounts of 5-HT were detected by fluorimetric assays in the lumen of isolated jejunal loops under resting conditions. The experiments demonstrate that :(i) 5-HTP is taken up not only into typical EC but also into other enteroendocrine cells, and most probably decarboxylated to 5-HT. (ii) Also intestinocytes take up [3H]-5-HTP and incorporate the amino acid into peptides to a certain extent. (iii) Following vagal nerve stimulation labelled material, probably 5-HT, is secreted into the gut lumen. (iv) 5-HT normally occurs in the gut lumen.

Engulfment of erythrocytes by intestinocytes of the rat ileum.

The innervation of ileal mucosa of normal, unanaesthetized male Wistar rats was investigated electronmicroscopically. The presence of RBC inside intestinocytes was a secondary, but frequent observation in 4 of 20 rats. No sign of hemorrhage or trauma of the tissue was noted, and the rats had not been exposed to any known toxic agent. The study demonstrates that also intestinocytes have the capacity to engulf RBC, as many other types of epithelial cells. However, previous demonstration of RBC phagocytosis of epithelia was performed in tissues where hemorrhage had occurred for various reasons. In contrast, the rats of the present study were considered normal, although the influence of unknown agents cannot be ruled out.

Bacterial translocation following abdominal trauma in humans.

Bacterial translocation in humans has been identified only with small bowel obstruction and in trauma patients. Our aim was to determine whether the occurrence of bacterial translocation correlates with clinical outcome in trauma patients. All patients requiring exploratory celiotomy for abdominal trauma over a 2-month period were considered for the study. Gross fecal contamination of the abdomen was the only exclusion criterion. Five patients with small bowel injuries without obvious contamination were included. Patients received preoperative antibiotics. Once surgical hemostasis and injury repair were complete, two mesenteric lymph nodes were harvested--one for quantitative culture, the other for electron microscopic evaluation. Postoperatively, patients were monitored for infection via temperature, white blood cell (WBC) count, and, when indicated, chest X-ray (CXR) and culture. Statistical analysis utilized ANOVA (P < 0.05 significant) and linear regression. Sixteen patients were included in the study. Fifteen patients sustained penetrating abdominal trauma, one blunt. Six patients presented in Class I hemorrhagic shock, four in Class II, and two in Class III. The remaining four were not in hemorrhagic shock. Thirteen patients demonstrated bacterial translocation: one by culture alone, nine by electron microscopy, and three by both culture and electron microscopy. Statistical analysis of these three groups and patients without evidence of infection failed to reveal significant difference in average age, injury severity, hospital days, or incidence of postoperative infection. Bacterial translocation occurs following abdominal trauma in humans. Electron microscopic evaluation of mesenteric lymph nodes demonstrated that the incidence of translocation is greater than anticipated by culture alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructural localization of lactic dehydrogenase in mouse mammary carcinoma cells.

Electron microscopic study of lactic dehydrogenase (LDH) was carried out in C3H mouse mammary carcinoma cells. Scattered cytoplasmic LDH granules were noted as well as around mitochondria and nuclear membrane. Control studies with normal breast tissues failed to show any activity. This observation suggests that LDH plays an important role in C3H mammary carcinoma and may be of use as an additional marker.

The vagal release of 5-hydroxytryptamine from enterochromaffin cells in the cat.

Enterochromaffin cells (EC) from the cat duodenum were studied before and after electrical efferent stimulation of the cervical vagi by means of electron microscopy and fluorescence histochemistry according to the Hillarp-Falck technique. From the same animals portal blood plasma was assayed for serotonin (5-HT) at various stages of the nerve stimulation. Within 15 min after the onset of vagal nerve stimulation there was a more than twofold increase of the portal 5-HT levels, which returned to normal after cessation of stimulation. There was also a pronounced reduction in the fluorescence intensity of EC demonstrating a lowered intracellular 5-HT level. Ultrastructurally there was evidence for basal exocytosis as well as for a release of osmiophilic material from the EC directly into the gut lumen after nerve stimulation. Together, these observations strongly suggest a vagally induced 5-HT release from EC in the cat.