Nanosecond-pulse fluorimetry of wheat-germ agglutinin (lectin)

Nanosecond-pulse fluorimetry of wheat germ agglutinin is analyzed as a function of both excitation and emission wavelengths. When excited at 280 nm, wheat germ agglutinin fluorescence exhibited three lifetimes: one corresponding to the tyrosine residues as a whole and two others corresponding to the tryptophyl emission. The tyrosine contribution to the emission spectrum deduced from this method was in good agreement with that reported previously in steady-state fluorescence experiments [Privat, J.P. and Monsigny, M. (1975) Eur. J. Biochem. 60, 555-567]. The fluorescence decay of each tryptophan residue was not a single exponential function when wheat germ agglutinin was excited at 295 nm. This could be related to the microenvironment of the indole chromophores in the protein. The comparison of the quantum yield and of average lifetime showed that some tryptophan residues were completely quenched. Energy transfer from tyrosines to tryptophan residues previously detected in steady-state fluorescence was also revealed by fluorescence decay measurements. Comparison of both methods showed that an important part of transfers occurred with a very fast rate equal to or greater than 10(10) s-1. Both lifetimes and the ratio of the short and the long-lived component were found dependent on tri-N-acetylchitotriose binding.     

Surgical treatment of renovascular hypertension

Two hundred sixty-four patients exhibiting renal artery occlusive disease underwent operation for renovascular hypertension between 1961 and 1977. Included were 27 pediatric patients. Fibrodysplastic disease affected 132 adults. Atherosclerotic lesions affected 51 patients with and 54 patients without clinically overt extrarenal arteriosclerotic cardiovascular disease. Ischemic kidney renin hypersecretion (renal: systemic index greater than 0.48), associated with suppressed contralateral kidney renin secretion (renal: systemic index approaching 0.0) predicted curability most reliably. Three hundred forty-eight operations were performed, of which 297 were primary and 51 were secondary procedures. Nephrectomy was initial therapy in 15 cases. Three operative deaths occurred among 51 patients manifesting overt extrarenal arteriosclerotic disease. No operative mortality was encountered among the other 213 patients. Surgical benefits were afforded 96% of pediatric patients and adults with fibrodysplastic disease, 91% of patients with focal renal arteriosclerosis, and 73% of those exhibiting overt extrarenal arteriosclerosis.     

Punctate pressure sensitivity: effects of skin temperature

The dependence on skin temperature of tactile sensitivity to punctiform (hair) stimulation of the finger tip came under study in five subjects. Their data show that punctate sensitivity is relatively stable over a wide range of thermal environments. On the average, some elevation of touch threshold occurred at a skin temperature of 20 degrees C (i.e., about 10 degree below normal), but severe loss of sensitivity first occurred at 10 degrees C. A small but possibly insignificant loss appeared at skin temperatures of 40 and 43 degrees C. The relatively stable behavior of the punctate threshold between about 20 and 40 degrees C contrasts with that of the vibrotactile threshold, which, at least for high frequencies, depends strongly on the skin temperature.     

Effect of low concentrations of quinolone antibiotics on bacterial virulence mechanisms

Recent studies have shown that exposure to quinolone antibiotics at or below the minimal inhibitory concentration (MIC) results in reduction in the level of production or total elimination of certain factors that contribute to the virulence of bacteria. This study was designed to determine whether low concentrations of enoxacin, lomefloxacin, and ciprofloxacin altered the morphology or affected the production of various virulence factors in several different genera of bacteria. The factors studied were nuclease and a toxin production in Staphylococcus aureus, cell size, pili and fimbriae production, and adherence of Salmonella typhimurium, Escherichia coli, and Pseudomonas aeruginosa to urinary epithelial cells and dog bladder cells, and the major virulence factor in Yersinia pseudotuberculosis. In addition, the effect of growth in low levels of enoxacin on phagocytosis of S. aureus by human polymorphonuclear leukocytes (PMNs) was studied. Following exposure to subinhibitory levels of quinolones tested, significant reduction in activity or complete elimination was seen in all of those factors measured. Minor differences were noted in the efficiency of elimination among the three quinolones tested. At as low as 1/8 MIC there is significant enhancement of phagocytic activity by human PMNs. These data suggest that exposure to quinolones at concentrations below the MIC disrupts the regulatory mechanisms that control cell morphology, adherence as well as exocellular enzyme production and plasmid maintenance. This may mean that certain virulent organisms that survive exposure to quinolone antibiotics may be less likely to produce or maintain the disease state in susceptible hosts.     

In vivo cerebral metabolism and central benzodiazepine-receptor binding in temporal lobe epilepsy

Positron emission tomography measured interictal cerebral glucose metabolism with [18F]fluorodeoxyglucose and central benzodiazepine-receptor binding with [11C]flumazenil in 10 mesial temporal lobe epilepsy (TLE) patients and in normal subjects. Eight TLE patients had mesial temporal, lateral temporal, and thalamic hypometabolism ipsilateral to EEG ictal onsets, with additional extratemporal hypometabolism in four. One had unilateral anterior mesial temporal hypometabolism only, and one had normal metabolism. Each patient had decreased benzodiazepine-receptor binding in the ipsilateral anterior mesial temporal region, without neocortical changes. Thus, interictal metabolic dysfunction is variable and usually extensive in TLE, whereas decreased central benzodiazepine-receptor density is more restricted to mesial temporal areas. Metabolic patterns in TLE may reflect diaschisis, while benzodiazepine-receptor changes may reflect localized neuronal and synaptic loss that is specific to the epileptogenic zone. [11C]Flumazenil imaging may be useful in presurgical evaluation of refractory complex partial seizures.     

Paraganglioma of the cauda equina: a case report and review of the literature

The authors describe the technique of RARE sequences (Hennig, 1986) and their hydrographic application to urinary imaging, RARE urography. Heavily T2-weighted non-tomographic images of the urinary tract are obtained in less than 30 seconds, without contrast medium or ionizing radiation. The whole urinary tract is visualised on one image with a spatial resolution superior to that of sonography. The semiology of RARE urography is similar to that of the intravenous pyelogram. Silent kidneys are also visualised.