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Biomedical subjects

J M Langloss

Publications and source records attributed to J M Langloss.

11 recordsLinked to original sources
PubMed1992

Glycoprotein hormone alpha-subunit-producing pituitary adenomas in rats treated for one year with calcitonin.

Calcitonin, a calcium-lowering hormone, has been associated with an increased incidence of nonfunctioning pituitary tumors in rats. In this study, rats were treated with calcitonin (80 IU/kg/d) for 52 weeks. After treatment with calcitonin, immunohistochemistry and in situ hybridization analyses demonstrated that most pituitary tumors expressed the glycoprotein hormone alpha-subunit. Expression of the alpha-subunit was identified rarely in hyperplastic lesions of control animals. Serum levels of GH, PRL, ACTH, LH, and FSH were unchanged in calcitonin-treated rats relative to controls. However, TSH levels were increased 2.1 fold after chronic treatment with calcitonin in both male and female rats (P less than 0.001). The level of glycoprotein hormone alpha-subunit was markedly increased (20-fold) in male rats with smaller elevations in female rats. Time course studies demonstrated that increases in serum alpha-subunit levels could be detected by 24 weeks of treatment and that elevations in alpha-subunit were present in the majority of animals by 40 weeks of treatment with calcitonin. The authors conclude that high doses of calcitonin, administered to rats for 6 months or longer, increases the incidence of alpha-subunit-producing pituitary tumors.

Adenoma↗
PubMed1990

Spindle cell carcinoma of the conjunctiva. An immunohistochemical and ultrastructural study of six cases.

Six cases of conjunctival spindle cell carcinoma, a rare variant of squamous cell carcinoma, were studied. The median age of the three men and three women was 63.5 years. The tumors appeared as a single nodule in some patients or diffusely involved the conjunctiva in others. Two of the four individuals with intraocular extension presented with phthisis bulbi. Polyclonal antikeratin antibody was helpful and gave the most consistent results when compared with monoclonal antikeratin antibodies, AE1/3 and PKK1. The electron microscopic study of four lesions also established the epithelial nature of the tumor cells. Intracytoplasmic tonofilaments and a few desmosomes were present. Histopathologically, this variant of squamous cell carcinoma is difficult to distinguish from other spindle cell tumors, and this study demonstrates the value of immunohistochemistry and electron microscopy in supporting the correct diagnosis.

Adult↗
PubMed1979

Elaboration of chemotactic substances by alveolar cells: possible mechanisms for the initial neutrophilic response in feline caliciviral pneumonia.

In vitro experiments established that the interaction of feline calicivirus (FCV) with alveolar macrophages and pneumocytes results in the generation of chemotactic factors that produce directed migration of neutrophils in Boyden chambers. Factors were produced independent of immune mechanisms and of discernible serum factors. Lysates of noninfected alveolar macrophages and pneumocytes did not possess chemotactic activity, indicating that chemotactic factors were not preformed in these cells. Noninfected alveolar macrophages also elaborated neutrophil chemotactic factors in culture; however, activity was greater when macrophages were infected with FCV. The results of this study suggested that the neutrophilic response in the peripheral portion of the lung of cats exposed to aerosols of FCV was the result of the elaboration of complete chemotactic factors from FCV-infected alveolar cells.

Animals↗
PubMed1978

In vitro interaction of alveolar macrophages and pneumocytes with feline respiratory viruses.

Feline alveolar macrophages and feline pneumocytes were inoculated in vitro with low multiplicities of either feline calicivirus or feline viral rhinotracheitis virus. Pneumocytes were permissive for both viruses. High titers were attained, and characteristic cytopathic effects developed. Alveolar macrophages were permissive for feline viral rhinotracheitis virus, although the cycle of replication was delayed. Infection of macrophages with feline calicivirus resulted in the production of viral antigens and cytopathic effects; however, viral particles were not detected by electron microscopy, and viral infectivity titers rose only slightly and then fell to undetectable levels by 96 h. The differences in viral susceptibility between these two peripheral pulmonary cell populations that were demonstrated in vitro probably contribute to the differences in pathogenesis of viral rhinotracheitis and calicivirus infections in cats.

Animals↗
PubMed1978

Experimentally induced feline chlamydial infection (feline pneumonitis).

Cats exposed to aerosols of feline Chlamydia psittaci developed a disease characterized principally by conjunctivitis. Signs of conjunctivitis appeared between postexposure days (PED) 5 and 10, were often unilateral initially, and persisted for 22 to 45 days. Fever followed the onset of conjunctivitis (PED 11 to 15) and persisted for 3 to 8 days. Signs of mild rhinitis (occasional sneezing and mild serous nasal discharge) occurred in some cats between PED 8 and 37. Neither signs of lower respiratory tract disease nor significant pulmonary lesions were produced by the feline pneumonitis agent. Small foci of pneumonia were detected microscopically in 3 of 6 cats examined between PED 7 and 14. Chlamydiae were identified between PED 7 and 14 in the cytoplasm of epithelial cells in stained conjunctival smears. Conjunctivitis persisted for at least 18 days after chlamydiae no longer were detectable in conjunctival smears. Low levels of chlamydial infectivity, however, still were present in conjunctiva and lung on PED 45.

Animals↗
PubMed1978

Ultrastructural morphogenesis of acute viral pneumonia produced by feline calicivirus.

The ultrastructural morphogenesis of acute viral pneumonia was studied in pathogen-free cats exposed to aerosols of a virulent strain of feline calicivirus. Electron microscopy and fluorescence microscopy indicated that the virus had a marked tropism for alveolar pneumocytes. Viral-induced necrosis of pneumocytes was observed as early as 12 hours after exposure and was associated with acute serofibrinous and neutrophilic inflammation in the distal air exchange tissue. The acute exudative phase abated by 168 hours after exposure. The regenerative phase that followed was characterized by hyperplasia of type II pneumocytes; influx of monocytes, lymphocytes, and plasma cells; and interalveolar and intraalveolar proliferation of fibroblasts. The decrease in pneumocyte injury coincided with the increase in alveolar macrophages and immunocytes. With minor exceptions, feline calicivirus-induced alveolar damage and the subsequent repair resembled toxic alveolar injury produced by oxidant gases. Feline caliciviral pneumonia, therefore, is a naturally occurring example of viral-induced diffuse alveolar damage.

Animals↗
PubMed1977

Diffuse alveolar damage in cats induced by nitrogen dioxide or feline calicivirus.

The ultrastructural morphogenesis of pulmonary lesions was studied in cats exposed to either aerosols of feline calicivirus (FCV) or high concentrations of NO2. Both directly injured alveolar lining cells, particularly type I cells. Necrosis of pneumocytes attended by an acute exudative response in the air exchange tissues was evident from 0 through 24 hours after exposure of cats to NO2 and from 12 through 96 hours after infection with FCV. The reparative process following alveolar injury was characterized by regenerative hyperplasia of type II pneumocytes, proliferation of stromal cells, and infiltration of mononuclear cells. Differences in the lesions produced by NO2 and FCV also were encountered. Endothelial necrosis was detected only after NO2 injury, whereas a marked infiltration of neutrophils and immunocytes was observed only after FCV injury. The FCV/NO2 experimental system in cats is well suited for studies of diffuse alveolar damage of toxic and viral etiology.

Animals↗
PubMed1976

Malignant intraocular teratoid medulloepithelioma in three dogs.

Tumors derived from the fully differentiated ciliary epithelium include adenomas and adenocarcinomas. Many such tumors in animal eyes have been reported. Medulloepitheliomas derived from the primitive medullary epithelium of the optic cup have rarely been seen in animal eyes. A teratoid variant of medulloepithelioma, recently described in human eyes, has also been seen in canine and bovine eyes. These tumors contain tissues resembling brain, cartilage, rhabdomyoblasts, and primitive mesenchyme, in addition to the poorly differentiated neuroepithelial and neuroblastic elements characteristic of malignant medulloepitheliomas.

Animals↗