Dissociation of saccade-related and pursuit-related activation in human frontal eye fields as revealed by fMRI

The location of the human frontal eye fields (FEFs) underlying horizontal visually guided saccadic and pursuit eye movements was investigated with the use of functional magnetic resonance imaging in five healthy humans. Execution of both saccadic and pursuit eye movements induced bilateral FEF activation located medially at the junction of the precentral sulcus and the superior frontal sulcus and extending laterally to the precentral gyrus. These findings extend previous functional imaging studies by providing the first functional imaging evidence of a specific activation in the FEF during smooth pursuit eye movements in healthy humans. FEF activation during smooth pursuit performance was smaller than during saccades. This finding, which may reflect the presence of a smaller pursuit-related region area in human FEF than the saccade-related region, is consistent with their relative size observed in the monkey. The mean location of the pursuit-related FEF was more inferior and lateral than the location of the saccade-related FEF. These results provide the first evidence that there are different subregions in the human FEF that are involved in the execution of two different types of eye movements, namely saccadic and pursuit eye movements. Moreover, this study provides additional evidence that the human FEF is located in Brodmann's area 6, unlike the monkey FEF which is located in the posterior part of Brodmann's area 8.     

Effect of Compositional Variations in the Lead Lanthanum Zirconate Stannate Titanate System on Electrical Properties

The purpose of this work was to evaluate the effect of compositional modifications on the electrical properties of lead lanthanum zirconate stannate titanate (PLZST) ceramics, as well as to examine their electrically induced phasechange behavior. Variations in the Ti:Sn ratio were evaluated. Increased Ti⁴⁺ content produced the following: decreased switching field, related to an increased antiferro-electric-ferroelectric (AFE-FE) transition temperature; constant hysteresis (Δ E ) correlated with a constant temperature of the maximum dielectric constant (T_max); a sharper dielectric-constant maximum peak; and increased room-temperature dielectric constant ( K ). Variations in the Zr:Sn ratio also were evaluated. Increased Zr⁴⁺ content produced the following: increased hysteresis with increased T_max , decreased maximum dielectric constant, and decreased switching field with increased AFE-FE transition temperature (T_AFE__FE). From these results, with respect to compositional modifications, the AFE-FE switching field (E_AFE__FE) and Δ E were observed to be dependent strongly on T_AFE__FE and T_max, respectively. Negligible change existed in the strain achievable at the switching field, which remained constant for all compositions at ∼0.16%. The significance of this research was the ability demonstrated to tailor the properties of phase-change materials through compositional modifications.     

Magnetic resonance imaging arthrography of the ankle

Magnetic resonance imaging (MRI) arthrography of the ankle is a useful diagnostic modality in the detection and staging of lateral ankle ligament tears, particularly in patients who fail to respond to conservative management. MRI arthrography also may be helpful in determining the extent of ligamentous injury in professional athletes, for whom immediate surgical repair may be the initial treatment. Preoperative planning is optimized with MRI arthrography. Frequently, alternative diagnoses may be made for conditions that can simulate lateral ligamentous injury, thus obviating the need for diagnostic arthroscopy.     

Isolation and characterization of novel endogenous digitalis-like factors in the ovary of the giant toad, Bufo marinus

We have previously described the structures of four novel unconjugated bufadienolides in the ovary of the toad, Bufo marinus. In this study, we report the separation and characterization of three novel bufadienolide conjugates. These compounds were purified by HPLC, and their structures were determined to be 11alpha, 19-dihydroxytelocinobufagin-3-(12-hydroxydodecanoic acid) ester, 11alpha,19-dihydroxytelocinobufagin-3-(14-hydroxy-7-tetra decenoic acid) ester, and 11alpha, 19-dihydroxytelocinobufagin-3-(14-hydroxytetradecanoic acid) ester on the basis of NMR and MS data. Numerous dicarboxylic acid esters of bufadienolides have previously been described, but the three bufadienolide conjugates described in this report differ from previously described esters in that they contain hydroxylated monocarboxylic acids. The function of these three conjugates is not known but they are, like bufotoxins, potent inhibitors of Na+, K+-ATPase and may play a developmental role in the differentiation of toad oocytes.     

Clinically significant drug interactions in dermatology

Several glycoproteins that are present at the nuclear rim and at the nuclear pore complex of tobacco suspension-cultured cells are modified by O-linked oligosaccharides with terminal N-acetylglucosamine (GlcNAc). Here, we report on the purification of several of these glycoproteins, which are referred to as terminal GlcNAc (tGlcNAc) proteins. In vitro galactosylation of the tGlcNAc proteins generated glycoproteins with terminal galactosyl-beta-1, 4-GlcNAc and thus permitted their isolation by Erythrina crystagalli agglutinin affinity chromatography. Peptide sequence information derived from one tGlcNAc protein with an apparent molecular mass of 40 to 43 kD, designated gp40, made it possible to clone its gene. Interestingly, gp40 has 28 to 34% amino acid identity to aldose-1-epimerases from bacteria, and no gene encoding an aldose-1-epimerase has been isolated previously from higher organisms. Polyclonal antibodies were generated against recombinant gp40. Consistent with its purification as a putative nuclear pore complex protein, gp40 was localized to the nuclear rim, as shown by biochemical fractionation and immunofluorescence microscopy.     

The characteristics of the immune response in acute viral hepatitis B

The clinical and pathogenetic importance of a number of features characterizing cell-mediated immunity and nonspecific protective factors in acute virus hepatitis B. 124 patients with hepatitis B virus (HBV) infection were placed under observation. Of these, 115 patients had acute virus hepatitis B, 6 patients had acute virus hepatitis of mixed etiology (B + delta) and 3 patients had chronic virus hepatitis B. The study included, besides the detection of virus hepatitis markers and the biochemical analysis of blood, the determination of subpopulations of peripheral blood lymphocytes (CD3, CD4, CD8, CD57), the functional activity of natural killers, characteristics of the interferon status, serum neopterin and beta 2-microglobulin in blood serum. Considerable changes in cell-mediated immunity and the interferon system were found to occur and the optimum immune response in acute virus hepatitis B was characterized.     

Clinical aspects of injury to the eye inflicted with gas pistols for self-defense

The clinical picture of an injury inflicted with gas pistols represents polymorphous changes and severe injury to the organ of vision, involving not only the anterior segment, but the deep structures as well. Analysis of the status of the damaged eyes and the mechanism of injury permitted us to distinguish 3 clinical groups in terms of the intensity of exposure to this or that factor: 1) chemical burn of the cornea and conjunctiva (65 patients); 2) chemical burn with elements of thermal involvement and impregnation of tissues with particles of gunpowder that failed to burn and slight or medium-severe contusion of the eyeball (31 patients): and 3) severe thermochemical burn with grave contusion of the eyeball, sometimes with rupture of membranes (6 patients). Hence, we may conclude that the consequences of using gas weapons differ from those described in the Status of Gas Weapons Application and in advertising materials by a much greater severity, and in 11.7% cases such injuries led to complete irreversible loss of vision. Obviously the shortest distance from which it may be allowed to shoot from gas pistols should be increased to 1 meter.