A. Connolly

Cytosolic free Ca2+ concentration ([Ca2+]i) was monitored in single and groups of fura-2-loaded bovine aortic endothelial cells (BAEC) during exposure to laminar fluid shear stress. Application of a step increase in shear stress from 0.08 to 8 dyn/cm2 to confluent BAEC monolayers resulted in a transient increase in [Ca2+]i, which attained a peak value in 15-40 s, followed by a decline to baseline within 40-80 s. The magnitude of the [Ca2+]i responses increased with applied shear stress over the range of 0.2-4 dyn/cm2 and reached a maximum at greater than 4 dyn/cm2. Transient oscillations in [Ca2+]i with gradually diminishing amplitude were observed in individual cells subjected to continuous high shear stress. Elimination of extracellular Ca2+ with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, blockade of Ca2+ entry with lanthanum, depolarization of the cell membrane with high K+, and preconditioning of BAEC in steady laminar flow had little effect on the [Ca2+]i response. In the presence of ATP or ADP, application of shear stress caused repetitive oscillations in [Ca2+]i in single BAEC, whose frequency was dependent on both agonist concentration and the magnitude of applied shear stress. However, apyrase, an ATPase and ADPase, did not inhibit the shear-induced [Ca2+]i responses in standard medium (no added ATP or ADP), suggesting that the shear-induced [Ca2+]i response is not due to ATP released by endothelial cells.

We prospectively studied the latest 60 patients who presented to the ENT Departments of St Mary's and St George's Hospitals with ingested foreign bodies. Localization of the foreign body by the patient was compared to the actual site of the foreign body at removal and graded accordingly. Localization was better the higher the object. When compared with objects above the cricopharyngeus muscle items impacted below this level were poorly localized (P < 0.0001) and lateralized (P < 0.0001). This suggests that for a patient who is able to lateralize a presumptive foreign body within the cervical region, then that object is likely to be above cricopharyngeus and on the side indicated. Further, it is likely to be visible on indirect laryngoscopy and amenable to removal in the casualty department. We hypothesize that the pharyngeal innervation by the vagus and glossopharyngeal nerves provides better sensation than in the oesophagus which is innervated less densely by the vagus and cervical sympathetic nerves.

Three hundred and sixty children who had a head and neck mass excised during 1987 to 1992 at the Royal Hospital for Sick Children, Glasgow were studied. There were 210 males and 150 females with a mean age of 60.7 months (0.5 to 198 months). Pilomatrixomata/sebaceous cysts (34 per cent), thyroglossal cysts (13 per cent), branchial remnants (nine per cent) and dermoids (nine per cent) accounted for almost two-thirds of the 264 non-lymphadenomatous benign lesions excised. Ninety-three lymphadenopathy masses consisted of 60 with reactive hyperplasia, 21 with Mycobacterium infection and 12 lymphomas. There were three solid malignant tumours, two were rhabdomyosarcomata and one disseminated round cell tumour. The correlation between clinical diagnosis and histopathology of benign non-lymph node masses and solid tumours was 90 per cent and 100 per cent respectively, in benign lymph nodes, 66 per cent, but was poor in differentiating lymph node content. The mean time from presentation of a swelling to its excision was almost a year and the mean in-patient stay for excision of a mass was almost five days. The role of fine needle aspiration cytology (FNAC) in arriving at a diagnosis and reducing patient morbidity is discussed.

To examine the control of pulsatile insulin secretion by an intrapancreatic pacemaker, samples at minute intervals were taken from the portal vein in dogs in vivo and from an isolated perfused pancreas preparation in vitro. Anesthetized dogs had high amplitude pulsatile insulin secretion which was not consistently regular. Fourier transform analysis showed dominant 20- and 10-min periods of spectral power (P less than 0.01). After vagotomy, the relative oscillatory power was reduced from 83% to 42%, about a lower mean concentration with abolition of the 20-min oscillations. The isolated perfused dog pancreas also had oscillatory insulin secretion with oscillatory power of 12%. Autocorrelation showed regularity of in vitro insulin secretion with a period of 10-11 min (P less than 0.0001). In addition, somatostatin was secreted from the in vitro pancreas in pulses in phase with insulin (cross-correlation P less than 0.0001). These data are in accord with the theory that the pancreas has an internal pacemaker which controls insulin secretion, and that the amplitude of the oscillations is modulated by vagal control. The pacing of the islets may be coordinated by a neural network, whereas coincident pulsatile somatostatin release may temporarily suppress islet secretion and help to synchronize hormonal oscillations.

Abstract The thermal conductivity, Ks, of superconductive tantalum and niobium has been measured between 0.2 and 1.2 °K, and for one niobium specimen between 0.2 and 4.2 °K. Large maxima in Ks occur in all three cases at ~ 0.2TC and Ks has been analyzed into its electronic and lattice components Kes and Kgs. Agreement between experiment and the B.C.S. theory is good for tantalum between T = 0.5TC and T = TC, where Kgs is small. Below 0.5TC conduction by phonons becomes appreciable. From the curves of Kgs against T the width of the energy gap at 0 °K has been deduced, giving (2Є0 =) 3.8 ± 0.2kTC for tantalum and (2Є0 =) 3.5 ± 0.2kTC for niobium.