EVIDENCE FOR DIRECT INTERACTION OF KETAMINE WITH α- AND β2-ADRENOCEPTORS

1. Ketamine has a number of effects that suggest that it may interact with α- and β-adrenoceptors. To date, the experimental evidence for this has been indirect and has been based on physiological studies using competitive blocking agents. In the present study we sought to determine from receptor binding studies whether ketamine binds directly to α- and β-adrenoceptors. 2. Membrane preparations o. α₁- and β₂-adrenergic binding sites were obtained from urinary bladder and urethrae of sheep. These binding sites were characterized by saturation analyses using [³H]-prazosin for α₁-adrenoceptor binding sites and [¹²⁵I]-cyanopindolol (CYP) for the β₂-adrenoceptor binding sites. The receptors were further characterized by displacement studies using selective and non-selective antagonists. 3. Studies in which ketamine was used to displac. [³H]-prazosin revealed a K_d of 3.40±1.23× 10^?3 mol/L for ketamine binding to ai-adrenoceptors. Displacement studies of [¹²⁵I]-CYP by ketamine showed a K_d of 0.35±0.03× 10^?3 mol/L for ketamine binding to β₂-adrenoceptors. 4. We conclude that ketamine interacts directly with both ai- an. β₂-adrenoceptors and that such interactions probably explain the reported effects of this agent on the vasculature and the bronchial tree.     

The advantages of delayed imaging and radiographic correlation in scintigraphic localization of gastrointestinal bleeding

Two cases in which gastrointestinal bleeding was localized by serial scintigraphic imaging with red blood cells labeled in vivo with 99mTc-PYP are reported. The importance of both early serial imaging and delayed imaging and of the correlation with other radiographic techniques is demonstrated. Reflux of blood from the sigmoid into the proximal colon was observed in both cases. In one case, contrast material injected into a resected specimen confirmed the scintigraphic localization of the site of bleeding.     

Neuropsychological and linguistic follow-up studies of children with galactosaemia from an unscreened population

Many galactosaemics appear to have neuropsychological and/or linguistic problems in spite of dietary treatment. Because the neonatal screening program in Norway does not include galactosaemia, we have re-examined Norwegian galactosaemics. Of 16 known patients, 8 patients participated in the study. They had been diagnosed between 2 and 11 weeks of age, and were between 9 months and 19 years old at the time of this study. All had very low or 0 activity of galactose-1-phosphate uridyl transferase. As part of the study all were examined neurologically, and had an age-appropriate developmental/IQ test, an ABR and an EEG, and a comprehensive psycholinguistic evaluation. The three youngest patients had normal developmental/IQ tests, while the five older patients had IQ scores in or below low range of normal. The majority had delayed language development and three patients were classified as having verbal dyspraxia. ABR and EEG showed mild pathology in the oldest patient only. Galactosaemia appears to be associated with significant risks of developmental and language delays in this unscreened population.     

Pancreas divisum: thin-section CT

Twelve patients with known pancreas divisum underwent thin-section computed tomography (CT) to determine the capability of CT to depict this pancreatic anomaly. Focal pancreatic enlargement was present in five patients. Two distinct pancreatic moieties separated by a fat cleft were noted in three patients; a fourth patient had focal atrophy in the distribution of the dorsal pancreas. The two pancreatic moieties were identified at the same craniocaudal level in all four of these patients. The dorsal duct was depicted in all 12 patients, while the short ventral duct was seen in only five of the 12 patients. Failure of the ventral and dorsal pancreatic ducts to fuse was identified in all five patients in whom both ducts were seen. CT may not enable specific diagnosis of pancreas divisum in the majority of patients. If, however, distinct pancreatic moieties or unfused ductal systems are evident, the diagnosis may be confidently suggested.