Acute unilateral pulmonary nonventilation due to mucous plugs

Acute bronchial obstruction by mucous plugs may be manifested clinically by dyspnea, hypoxemia, and respiratory alkalosis mimicking pulmonary thromboembolism. In eight cases with complete interruption of ventilation to an entire lung, chest radiography failed to reveal the extent of the obstruction. Perfusion was substantially less affected than ventilation. Routine ventilation-perfusion scintigraphy with technetium-99m DTPA aerosol aids in the diagnosis of acute major bronchial obstruction in patients with suspected pulmonary thromboembolism.     

Spontaneous internal carotid artery dissection shown by magnetic resonance imaging

We have reported a case of spontaneous dissection of the internal carotid artery, with MRI and angiographic findings. We conclude that MRI is a beneficial noninvasive test for the detection and study of carotid artery dissection.     

Short-term desensitization of prostaglandin F2 alpha receptors increases cyclic AMP formation and reduces inositol phosphates accumulation and contraction in the bovine iris sphincter

The effect of short-term prostaglandin (PG) desensitization on PGF2 alpha receptor-mediated inositol phosphates accumulation, 1,2-diacylglycerol production, measured as phosphatidic acid (PA), myosin light chain (MLC) phosphorylation, cAMP formation and contraction was investigated in bovine iris sphincter smooth muscle. We have found that incubation of the sphincter with 25 microM PGF2 alpha for 45 min leads to: (a) significant loss in sensitivity of the tissue to PGF2 alpha receptor-stimulated inositol phosphates accumulation, PA production, MLC phosphorylation and contraction, and (b) significant increase in both basal and PGF2 alpha-stimulated cAMP formation. These changes are probably not due to reduction in phospholipid synthesis because there were no detectable differences in basal phospholipid labeling, either from 3H-inositol or from 32P, between normal and desensitized muscles. Preincubation of the sphincter in the absence of PGF2 alpha for 45 min did not lead to alterations in the biochemical-pharmacological responsiveness of the control muscle to PGF2 alpha. Our results suggest that desensitization of PG receptors in the iris sphincter occurs by a receptor-specific process. The PG receptor mediating contraction (IP3-Ca2+) is selectively susceptible to desensitization, in contrast with the receptor mediating smooth muscle relaxation (cAMP). These findings add further support to the developing hypothesis that there are functional and biochemical reciprocal interactions between the IP3-Ca2+ and cAMP messenger systems in the iris of the mammalian eye.     

Fatigue fractures of the femoral diaphysis in the skeletally immature simulating malignancy

The clinical and radiological features of three fatigue fractures developing along the medial aspect of the distal femoral diaphysis are described. All three patients were skeletally immature and were referred with the radiographic diagnosis of a probable sarcoma of bone. The plain radiographic findings consisted of an uninterrupted single lamella of periosteal new bone arising medially from the distal femoral diaphysis. Bone scans showed no evidence of hyperaemia on the vascular phase and revealed a fusiform focus of increased uptake in the postero-medial cortex of the lower femoral diaphysis on the 3-h images. Computed tomography showed increased attenuation of the medulla due to fibrosis and an absence of a soft-tissue mass. Periosteal callus was present and a cortical fracture through the medial femoral cortex was identified in two cases. The features that distinguish a fatigue fracture of the femur from a sarcoma are discussed.     

Pancreatic carcinogenesis: effect of secretin in the hamster- nitrosamine model

The effect of exogenous secretin on pancreatic carcinogenesis in WO strain hamsters has been examined in the nitrosamine-ductular adenocarcinoma model. Secretin, 20 clinical U/kg, stimulated a maximal secretory response of pancreatic juice and bicarbonate when given iv. The same dose given sc for 6 weeks had no significant effect on pancreatic wet weight and DNA or RNA contents. However, when given to animals receiving N-nitrosobis(2-oxopropyl)amine [(BOP) CAS: 60599-38-4] (5 mg/kg), it reduced the latency and increased the induction rate of tumor development when compared with the carcinogen given alone to animals (secretin + BOP, 15 of 17 animals with tumors; BOP alone, 4 of 13 with tumors at 15 wk; P less than .002). These effects are consistent with secretin acting as a cocarcinogen in this model of pancreatic carcinogenesis.     

Pulsatile masses surrounding vascular prostheses: real-time US color flow imaging

A prospective evaluation of color flow mapping and real-time ultrasound was performed to determine if pseudoaneurysms could be distinguished from other causes of masses surrounding vascular grafts of the lower extremities. Twelve palpable pulsatile masses were imaged. Diagnoses were confirmed at angiography (n = 11), computed tomography (n = 7), aspiration biopsy (n = 5), and operative intervention (n = 6). A swirling pattern of blood flow was seen in six of seven cases of pseudoaneurysm. Lack of flow signals was noted in four of the five collections representing hematoma (n = 2) or infection (n = 2). The seventh case was later shown to be an infected, thrombosed pseudoaneurysm. The single false-positive diagnosis was made early in the series when the flow signals detected were due to transmitted arterial pulsations. The authors conclude that color Doppler flow imaging is useful in the differential diagnosis of pulsatile masses associated with prosthetic grafts. Prosthetic graft pseudoaneurysms have a specific appearance of swirling blood flow arising from a wide neck and are distinguishable from traumatic or iatrogenic pseudoaneurysms of the native vascular tree.     

Rapid and accurate stability-indicating assay for nitroglycerin.

A rapid high-pressure liquid chromatographic method for determining the nitroglycerin concentration in liquid dosage forms and intravenous admixture solutions is presented. A coefficient of variation of less than 1.8% was achieved over the concentration range most commonly encountered (50-500 microgram/ml). A variable wavelength detector (lambda = 218 nm) and a micro-alkyl phenyl column were employed. The mobile phase was acetonitrile-tetrahydrofuran-water (26:10:64). Total analysis time was 12 min.