Inhibition of phospholipase D blocks activation of fibrinogen-adherent neutrophils by tumor necrosis factor.

Tumor necrosis factor stimulates fibrinogen-adherent neutrophils to produce a dramatic oxidative burst; the resulting superoxide and other products may contribute to tissue damage in severe infection. Inhibitors of the phospholipase D pathway blocked this activation without affecting cell adherence or nonspecific activation by phorbol myristate acetate. The phospholipase D pathway appears to be involved in the activation of adherent neutrophils by tumor necrosis factor, and this pathway may be a target for modulation of tumor necrosis factor's effects.     

Accuracy of passive ankle joint positioning during quiet stance in young and elderly subjects

Age-related postural deficits elicit compensatory mechanisms such as ankle dorsiflexion in the elderly. To gain further insight into this problem, the ability to match an ankle angle during quiet stance was studied in 12 elderly and 12 young subjects. Following an initial single limb angular perturbation presented in the ±4° range, a subject had to return a tilt platform to level, as determined by the nonperturbed limb. Elderly subjects exhibited significant positive (0.9°) over-shoot of the level position, in contrast to young subjects who matched ankle angle with a mean error of −0.1°. The elderly group also exhibited an increase in positioning error for angular displacements in the range between −1 and +1°. The results document age-related postural changes in ankle positioning which might affect postural stability in older adults.     

Strain differences in kinetic and thermal stability of two mouse brain tryptophan hydroxylase activities

Levels of forebrain serotonin (5-HT), tryptophan, 5-hydroxyindoleacetic acid (5-HIAA) and hydroxylase cofactor (BH₄) were comparable in two experimental mouse strains (A/J and C57B1/6J) despite 2–3-fold differences in vitro in the relative activities of forebrain and midbrain tryptophan-5-monooxygenase (TPOH; EC 1.14.16.4). The enzyme activities did not differ with respect toK_m for cofactor at saturating levels, but manifested different degrees of cooperativity with respect to cofactor when examined with BH₄ concentrations within a physiological range. They differed also in the frequency and amplitude of kinetic variation around comparable mean velocity slopes across cofactor and time; in resistance to pre-incubation inactivation and responsiveness to its facilitation by calcium; in molecular weight heterogeneity as reflected in the distribution of molecular weight forms by gel diffusion chromatography; and in the number of peaks in power spectral analysis of kinetic variation patterns. Although the potential roles of small-molecule ligand and/or regulator proteins have not been ruled out, we hypothesize that differences in conformational stability underlie the differences in regulatory properties and make one enzyme activity more vulnerable to occlusive influences in vivo.     

Oxygen-transmitting hard contact lenses.

Nine PMMA contact lens wearers with persistent corneal edema were refitted with CAB contact lenses. All of the patients showed less corneal swelling with CAB lenses than with PMMA lenses.     

The pedicle in neurofibromatosis.

Three cases of von Recklinghausen's disease (neurofibromatosis) are described, one with agenesis of a pedicle, another with multiple hypoplastic pedicles, and a third with bilateral hypoplastic pedicles producing a spondylolistesis. These peidcle deficiencies are manifestations of mesodermal dysplasia. Agenesis of the pedicle most likely represents a defect in chondrification. Hypoplasia probably represents a partial lack of development of the pedicle and the ipsilateral arch. Hypoplasia or agenesis of a pedicle should suggest the possibility of underlying neurofibromatosis.     

The effects of chronic administration of some cholinergic and adrenergic drugs on the activity of choline acetyltransferase in the optic lobes of the chick brain

Chicks receiving methadrine, reserpine and 6-hydroxydopamine for 2 or 3 days showed significant increases in optic lobe choline acetyltransferase. Atropine and neostig-mine did not produce this change. The methadrine-induced change occurred within 6 hr. Methadrine did not activate this enzyme in vitro however. This latter finding and the failure of acetoxycycloheximide to decrease measurable enzyme in 6 hr, suggests that the ampheta-mine-induced increase may be due to an increase in synthesis of choline acetyltransferase rather than either a steric activation or a decrease in degradation of the enzyme.