Response of the human oesophagus to d-tubocurarine and atropine

Intraluminal manometric studies of normal swallowing activity fail to distinguish between the peristaltic response of striated and smooth muscle. Studies were performed to determine if the two types of musculature differ in their response to pharmacological stimulation. After the administration of d-tubocurarine, peristaltic amplitude in the striated muscle segment decreased by 26 to 51%, while amplitude in the smooth muscle portion was not significantly affected. The administration of atropine, on the other hand, abolished or diminished smooth muscle peristalsis without altering striated muscle activity. The injection of neostigmine restored peristaltic amplitude toward normal in both striated and smooth muscle portions. These studies demonstrate that although the striated and smooth muscle segments are indistinguishable during normal oesophageal peristalsis, they do differ markedly in their pharmacological response. Pharmacologically, oesophageal striated muscle responds like other striated muscle and oesophageal smooth muscle responds like smooth muscle elsewhere.     

The New Mexico experiment: educational innovation and institutional change

Over the past ten years the University of New Mexico School of Medicine has conducted an educational experiment featuring learner-centered, problem-based, community-oriented learning. The experiment was introduced into an established institution by means of an innovative educational track running parallel to the more conventional curriculum. Students in the innovative track, compared with those in the conventional tract, tended to score lower on the National Board of Medical Examiners (NBME) Part I examination (basic sciences) and higher on NBME Part II (clinical sciences), received higher clinical grades on clinical clerkships, and experienced less distress. They were more likely than conventional-track students to retain their initial interest in or switch their preference to careers in family medicine. The parallel-track strategy for introducing curriculum reform succeeded in fostering institutional acceptance of continuing educational innovation. Generic steps in overcoming institutional barriers to change are identified.     

Coronary spasm associated with urticaria: Report of a case mimicking anaphylaxis

Recent investigations suggest that the vasoactive substances, histamine, prostaglandin E₂, and thromboxane A₂ are mediators of coronary artery spasm. These substances may be released during an episode of urticaria. We report here a case of coronary artery spasm associated with an episode of acute urticaria. The coronary spasm may have been mediated by the vasoactive substances released from basophils and secondary platelet aggregation, known to occur with urticaria.     

Immunological memory induced by genetically transduced tumor cells

Background: Recent studies have demonstrated the usefulness of gene-modified tumor cells for immunotherapy. Using the tumorigenic murine fibrosarcoma, MCA 106, we investigated the effects of localized interferon-γ (IFNg) secretion on tumorigenicity and on long-term memory. Methods: The murine IFNg (MuIFNg) gene was introduced into tumor cells. High and low IFNg-secreting clones were isolated. C57BL/6 mice were injected subcutaneously (s.c.) with either parental (P), high or low IFNg-secreting (H- or L-IFNg) cells, and tumor growth was assessed weekly. Spleens were harvested on different days postinjection (p.i.) to assess in vitro cytolytic activity. In parallel, tissues from injection sites were stained with macrophage-, CD4-, and CD8-detecting antibodies. Mice were injected s.c. with H-IFNg MCA106 tumor. After 150 days the animals were rechallenged s.c. with MCA106P in one leg and with irrelevant syngeneic tumor in the other. Results: Both P- and L-IFNg cells had similar growth, whereas the H-IFNg cells never grew. Only splenocytes from the H-IFNg animals showed in vitro CTL activity persisting until day 30 p.i. Histological data revealed a macrophage and CD4⁺ infiltrate much earlier in the H-IFNg group compared with the P group. Only the irrelevant, syngeneic tumor grew in animals previously injected with H-IFNg cells, whereas both P and irrelevant syngeneic tumors grew in controls. Conclusions: Transduction of MCA106 cells with the MuIFNg gene diminished in vivo tumorigenicity in proportion to the amount of IFNg secreted. Immunization with H-IFNg cells elicited a host response characterized by macrophages and CD4⁺ cells. Long-term tumor-specific memory was seen after immunization with H-IFNg cells.     

The effect of visual deprivation on canine gastric secretion

In 13 dogs with gastric cannulas the acid output per hour was determined after: (a) subcutaneous injection of 0.1 mg histamine (base), (b) subcutaneous injection of 1.0 mg histamine (base), (c) teasing with meat (10 min interval), (d) intravenous injection of 1.0 units/kg of insulin. The pepsin concentration was also determined after the intravenous injection of 1.0 units/kg of insulin. The range and average acid output and pepsin concentration were established for each test condition per dog. Vision was compromised in the dogs by ablation of the orbits, collapse of the orbits, and by occipital cortical lesions. Gastric secretory studies were repeated at intervals over a 4 month period. There was marked inhibition of acid output and pepsin concentration in all dogs for the entire 4 month period to all gastric stimuli.Acknowledgment is made to medical students Alan C. Leshnower, Dennis G. Westmoreland and John M. Eisenberg; to Jan Rubion, University of Tennessee Clinical Research Center, for the pepsin determinations; to Robert H. Murray, Surgical Research Laboratories, VA Hospital, Memphis, Tenn; to Lena Haney for histologic preparations; and to T. Bond for handling the statistical material.Supported in part, by Grant GB-7687 from the National Science Foundation.Supported by General Research Grant FR-05423, NIH, US Public Health Service.Supported by Research Grant FR-00211, US Public Health Service.     

Pseudoaneurysms complicating organ transplantation: roles of CT, duplex sonography, and angiography

In a retrospective study of proved pseudoaneurysms (PAs) in 15 patients with transplanted organs (11 liver, three kidney, one pancreas), the results of computed tomography (CT), duplex sonography, and angiography were reviewed. Of the 15 cases of PA, eight occurred at the arterial anastomosis and seven were nonanastomotic. Three of the eight anastomotic PAs were caused by infection. Of the seven nonanastomotic PAs, four were caused by percutaneous biopsy, two were caused by infection, and one was of undetermined cause. In nine (60%) of the 15 patients the PAs were incidentally detected at imaging studies performed for other reasons. Diagnosis requires a high degree of suspicion. CT was performed in nine cases and duplex sonography in ten. The diagnosis of PA was made with CT in six (67%) patients and with duplex sonography in five (50%). CT and duplex sonography could not enable diagnosis when the PA was small, when the arterial anastomosis was not included in the field of study, or when enhancement with intravenously administered contract material was suboptimal. Angiography depicted the PAs in all 15 patients. In three liver transplant recipients with gastrointestinal tract bleeding, the causative PAs were detected only with angiography.