Biomedical subjects
Publications and source records attributed to N Chan.
Seat belt-induced blunt abdominal trauma can result in a condition that both clinically and pathologically simulates Crohn's disease. Prompt recognition of this sequel to injury can save prolonged morbidity.
A 41-year-old man was found to have a malignant mesothelioma of the pleura. During childhood in Corsica, he had been exposed at home to chrysotile ore from the Canari mine. Analysis of lung mineral content revealed background levels of chrysotile but an elevated level of tremolite and actinolite asbestos. The latter had a geometric mean length of 3.7 microns, a value considerably longer than we have found for tremolite and actinolite from Quebec chrysotile miners but roughly the same as the mean length of amosite and crocidolite in workers with occupational amphibole exposure. No tremolite or actinolite fibers of length greater than 8 microns microns and width less than 0.25 micron were observed. The mean aspect ratio of the tremolite and actinolite fibers was 7, a value similar to that found in chrysotile miners with mesothelioma but considerably less than the mean aspect ratio of amosite and crocidolite from those with occupational exposure. These data suggest that long-fiber tremolite is a potential mesothelial carcinogen in humans, and that fiber length is more important than fiber aspect ratio in this regard.
Idiosyncratic pulmonary reactions to nitrofurantoin are not unusual, often presenting as eosinophilic pneumonia. We report two cases of uncommon pathological reactions, one resembling a hypersensitivity pneumonitis and the other mimicking a giant cell interstitial pneumonia.
To examine for a relationship between in vivo nonspecific bronchial reactivity to histamine and in vitro smooth muscle response to histamine, we performed inhalation dose-response curves prior to lung surgery in 12 patients and compared this with their bronchial smooth muscle response in vitro. In vivo reactivity was assessed by the provocative concentration of histamine resulting in a 20% fall in forced expiratory volume in one second (PC20), and in vitro reactivity was measured by the negative log of the molar concentration of histamine producing 50% maximal contraction (pD2) as well as maximal tension generated (Tmax). In addition, morphometric analysis was performed on the in vitro tissue to quantitate the amount of smooth muscle present. A wide range of in vivo responses was found in the 12 subjects (PC20-0.065 lead to 16). There was less in vitro variability and no correlation between PC20 and in vitro reactivity assessed by pD20 or Tmax or between PC20 and the percent of smooth muscle.
The performance of enzyme immunoassays (EIAs) with use of O-antigen-containing lipopolysaccharides (LPSs) extracted with phenol-water from Shigella dysenteriae type 1, Shigella flexneri serotypes 1a-5b, and Shigella sonnei for determination of the serum antibody responses after onset of bacillary dysentery is reviewed. For the purpose of several studies, serum samples from a total of 175 Vietnamese and 47 Swedish patients, for whom Shigella species had been isolated from fecal specimens, were obtained at various intervals until less than or equal to 1 year after the onset of infection. Titers of antibodies in serum samples from infected patients were compared with those in serum samples from healthy control subjects; the combined control population of all studies comprised 426 Vietnamese and 154 Swedes. The sensitivity of the EIAs ranged from 78% to 100% for patients whose fecal culture was positive for Shigella. For diagnosis of S. flexneri, a species-specific but no serotype-specific assay based on LPS antigens is possible. Among Vietnamese patients the EIA with use of S. flexneri was sensitive and diagnostic only for children less than 3 years of age, most likely because healthy older Vietnamese children and adults have high titers of antibody to the O-antigens of S. flexneri. Among Swedish patients the same EIA was diagnostic for adults as well as children. Increased titers of IgA in the early phase and of IgG in the convalescent phase, as determined by EIA, were the best indicators of infection due to Shigella species.
We describe an end stage renal disease (ESRD) patient on maintenance hemodialysis who developed a spontaneous increase in erythropoiesis associated with an episode of viral hepatitis. Resolution of the hepatitis was accompanied by a reduction in erythropoiesis with the hemoglobin and hematocrit falling back toward the patient's low baseline levels. Plasma erythropoietin (Ep) titers were measured during the period of active erythropoiesis and were found to be low to low normal. The unusual phenomenon of increased erythropoiesis in ESRD following liver injury has been previously described and is thought to be mediated through increased hepatitic Ep production. The low Ep titers measured in our patient, however, suggest that the liver may be capable of stimulating erythropoiesis by another mechanism.
Synthetic peptides were used as models for studying the conformation of ice nucleation proteins. We chemically synthesized four peptides (16-, 24-, 32-, and 48-mer) that consisted of two to six repeats of the consensus repeating octapeptide unit of ice nucleation proteins and evaluated their conformation by circular dichroism spectroscopy. These model peptides exist predominantly as random coils in aqueous solution, but adopt alpha-helical structures in the presence of trifluoroethanol. The stability of their secondary structures was investigated by monitoring the pH and time dependence of their circular dichroism spectra. Our results indicated that the alpha-helical content of the 48-mer exhibited a significant pH dependence, while that of the 24- and 32-mer peptides did not. The 32-mer was the only peptide that transformed from the alpha-helical to a beta-sheet structure upon storage. We suggest that the overall conformation of the ice nucleation protein could be a beta-sheet.
Despite the improved success of lung transplantation, ischemia of the donor bronchus continues to be the most important factor influencing airway healing. Recent studies have shown that at the level of the mainstem bronchi the pulmonary contribution to the airway blood flow may be equivalent to or greater than the systemic contribution and could therefore assist early healing of the newly anastomosed bronchus and, in addition, might facilitate the improved healing associated with omentopexy. The aim of this study was to measure the pulmonary contribution to airway blood flow in dogs after allotransplantation of the left lung and to determine whether omentopexy might improve the healing process. Using the radioactive microsphere technique, we measured the pulmonary contribution to airway blood flow in 25 dogs 1 week after allotransplantation of the left lung. Half the dogs had an omental wrap around the anastomotic site. Results showed that pulmonary blood flow increased progressively from lower trachea to distal mainstem bronchus and supplied the left mainstem bronchus above as well as below the anastomotic site. Omentopexy did not increase flow or enhance healing.
Fine needle aspiration (FNA) of a neck mass yielded cytologic specimens containing two cell populations: multinucleated giant cells and smaller, round-to-oval, undifferentiated malignant cells. The giant cells were frequently so numerous as to obscure the other cells. The FNA cytodiagnosis of a rare anaplastic thyroid carcinoma containing osteoclastic giant cells was substantiated by the subsequent exploratory surgery and biopsy specimen. Immunohistochemical staining suggested a dual origin of the two cell populations.
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