Unsubstituted hydrolyzed waxy maize as a potential agent for centrifugal leukacytapheresis

In order to determine whether newer, possibly safer erythrocyte sedimenting agents could be used during centrifugal leukacytapheresis, we tested seven varieties of plant starch. Only waxy maize prepared by partial acid hydrolysis appeared suitable, and it was tested extensively on an analytical device developed especially for testing erythrocyte sedimentation under the conditions of residence time, force, and sedimenting agent concentration used in a cell separator. This species of waxy maize, however, was not quite as effective a sedimenting agent when compared to hydroxyethyl starch (HES 450/0.70) under the test conditions used. Although chromatographic analysis showed the average molecular weights of the unsubstituted waxy maize were considerably higher than those of HES 450/0.70, degradation of waxy maize to smaller molecular weight fragments occurred more rapidly. The rapid degradation of this material may offer significant advantages during centrifugal leukacytapheresis procedures, but additional studies of its storage stability are needed.     

Obstructed calycocystostomy site in association with a transplanted kidney: percutaneous management

We have used advanced endourologic techniques in the treatment of an obstructed lower-pole calycocystostomy site. The unusual clinical course that led to this problem and the interventional treatment used are discussed.     

Migraine trigger factors in a non-clinical Mexican-American population in San Diego county: implications for etiology

We conducted an investigation of migraine headache in a general population of Mexican-Americans living in San Diego county. Specific headache triggers were reported and analyzed, the most frequently reported for females with migraine being missing meals (58.9%), weather changes (54.4%), menstruation (53.6%), post-crisis letdown (52.7%), and fatigue (51.8%). The most frequently reported trigger factors for migraines reported by males were fatigue (58.8%), sleep (as a precipitating factor) (56.3%), post-crisis letdown (41.2%), and weather changes (37.5%). Trigger factors were further evaluated using stratification by presence or absence of Raynaud's phenomenon (RP), menstrual migraine, family history of migraine, and by migraine type. Odds ratios and 95% confidence intervals were calculated. These results suggest that subjects with migraine and RP (perhaps indicative of a systematic vascular tone disorder) and those with menstrual migraine (indicative of sensitivity to hormonal changes) may overall be more sensitive to certain environmental stimuli, particularly those involving change in the internal environment.     

Three conserved motifs in the extracellular domain of the human granulocyte-macrophage colony-stimulating factor receptor subunit are essential for ligand binding and surface expression

The receptor for the human granulocyte-macrophage colony-stimulating factor (GM-CSF) (GM-R) is a heterodimeric complex consisting of two subunits, GM-R alpha and GM-R beta. Structural analyses have shown a number of highly conserved amino acid motifs present in both GM-R alpha and GM-R beta. These motifs include QYFLY, CXW, XW, and WSXWS motifs in the extracellular domain; a conserved cysteine in the transmembrane domain; and the entire cytoplasmic domain, including the LXVLX box in the carboxy terminal region of the cytoplasmic domain. We have investigated the role of these motifs in GM-R alpha by examining the effects of specific motif mutations on ligand binding and surface expression. Transient expression of these mutant GM-R alpha subunits in COS cells shows that these extracellular motis are essential for ligand binding. Alterations of the cytoplasmic region of GM-R alpha do not alter GM-CSF binding or the reconstitution of high-affinity receptors when coexpressed with GM-R beta. Permeabilization and immunostaining of cells transfected with mutant GM-R alpha subunits yields data suggesting that each of the mutant subunits is present in the cytoplasm. Immunostaining of both intact and permeabilized COS cells transiently transfected with wild-type or mutant GM-R alpha s showed that extracellular domain mutants accumulated in the cytoplasm and were not efficiently transported to the cell surface.     

Long-Term Thresholds of Nonsteroidal Permanent Pacing Leads: A 5-Year Study

The present commercial market supports many nonsteroidal endocardial pacing leads of differing construction. In order to compare the performance of these configurations, we studied the long-term pacing properties of three representative lead types by randomized clinical trial in 99 patients undergoing a first elective VVl implant. Thirty-one patients received sintered platinum leads, 36 activated pyrolytic carbon leads, and 32 vitreous carbon leads. All received generators capable of noninvasive threshold testing. Acute sensing parameters were R wave amplitude and ST segment elevation measured from the endocardial electrogram. Noninvasive voltage thresholds were measured at implantation, 2 days, 1, 3, and 6 months, and yearly thereafter for 5 years. There were no significant differences between leads in pacing or sensing capabilities at implantation. All three demonstrated similar increases in thresholds, peaking at 1 month, then falling to a plateau by 6 months and did not vary significantly thereafter. There were no significant differences in thresholds between leads during 5 years of follow-up. The lowest mean threshold at 5 years was 0.93 V at 0.5 ms. This study suggests that: (1) although these lead types all perform well, none offers any particular clinical advantage over another; (2) the degree of early threshold peaking precludes immediate postimplant output reduction, but later thresholds are sufficiently low to enable reductions in pacing output; (3) safe low energy pacing requires greater attention to the lead-generator combinations; (4) data obtained at subsequent annual follow-up provided no additional useful clinical information to that obtained at 1 year, and (5) in the absence of other differences, cost can be the deciding factor in lead selection.