Comparison of acceleration subjects to other populations: spinal anomaly distribution

Prior studies demonstrate an inconsistent relationship between occupational inorganic lead exposure and simple reaction time (SRT) performance. In this study, we administered a computerized SRT test to 78 currently employed lead smelter workers and then investigated the relationship between different measures of blood lead and components of SRT performance. The measures of blood lead included current blood lead (PbB) and mathematically derived blood lead fractions from the environment (PbB-env) and from bone (PbB-bn). Measures of SRT performance, obtained from 44 trials with interstimulus intervals (ISIs) ranging from 1 to 10 seconds, included median SRT (SRT-md), mean SRT for ISIs between 1 and 5 seconds (SRT-1-5), and mean SRT for ISIs between 6 and 10 seconds (SRT-6-10). Multiple regression analysis after adjustment for age and education revealed a curvilinear relationship between PbB and SRT-md. As PbB increased from 0 to 30 micrograms dl-1, SRT-md decreased, and only with PbB levels above 30 micrograms dl-1 did SRT-md increase. PbB terms accounted for 13.7% of the variance in this SRT measure (P < 0.01). The longer ISI variable, SRT-6-10, was found to be more strongly related to PbB, to have lesser variability across ISIs, and to be unrelated to age. Additional multiple regression analysis to examine the relationship between components of SRT and the PbB fractions, PbB-env and PbB-bn, showed only PbB-env to account for significant variance in SRT-md, (14.4%, P < 0.01), SRT-1-5 (9.7%, P < 0.03), and SRT-1-6 (15%, P < 0.01). We conclude that the relationship between PbB and SRT is U-shaped, that the SRT measure SRT-6-10 has properties that make it the preferred measure of SRT performance in future studies, and finally that only PbB-env, and not PbB-bn, is related to components of SRT.     

Purification of the lysosomal sialic acid transporter. Functional characteristics of a monocarboxylate transporter

Sialic acid and glucuronic acid are monocarboxylated monosaccharides, which are normally present in sugar side chains of glycoproteins, glycolipids, and glycosaminoglycans. After degradation of these compounds in lysosomes, the free monosaccharides are released from the lysosome by a specific membrane transport system. This transport system is deficient in the human hereditary lysosomal sialic acid storage diseases (Salla disease and infantile sialic acid storage disease, OMIM 269920). The lysosomal sialic acid transporter from rat liver has now been purified to apparent homogeneity in a reconstitutively active form by a combination of hydroxyapatite, lectin, and ion exchange chromatography. A 57-kDa protein correlated with transport activity. The transporter recognized structurally different types of acidic monosaccharides, like sialic acid, glucuronic acid, and iduronic acid. Transport of glucuronic acid was inhibited by a number of aliphatic monocarboxylates (i.e. lactate, pyruvate, and valproate), substituted monocarboxylates, and several dicarboxylates. cis-Inhibition, trans-stimulation, and competitive inhibition experiments with radiolabeled glucuronic acid as well as radiolabeled L-lactate demonstrated that L-lactate is transported by the lysosomal sialic acid transporter. L-Lactate transport was proton gradient-dependent, saturable with a Km of 0.4 mM, and mediated by a single mechanism. These data show striking biochemical and structural similarities of the lysosomal sialic acid transporter with the known monocarboxylate transporters of the plasma membrane (MCT1, MCT2, MCT3, and Mev).     

Muscle contraction as a Markov process. I: Energetics of the process

Force generation during muscle contraction can be understood in terms of cyclical length changes in segments of actin thin filaments moving through the three-dimensional lattice of myosin thick filaments. Recent anomalies discovered in connection with analysis of myosin step sizes in in vitro motility assays and with skinned fibres can be rationalized by assuming that ATP hydrolysis on actin accompanies these length changes. The paradoxically rapid regeneration of tension in quick release experiments, as well as classical energetic relationships, such as Hill's force-velocity curve, the Fenn effect, and the unexplained enthalpy of shortening, can be given mutually self-consistent explanations with this model. When muscle is viewed as a Markov process, the vectorial process of chemomechanical transduction can be understood in terms of lattice dependent transitions, wherein the phosphate release steps of the myosin and actin ATPases depend only on occurrence of allosteric changes in neighbouring molecules. Tropomyosin has a central role in coordinating the steady progression of these cooperative transitions along actin filaments and in gearing up the system in response to higher imposed loads.     

Split-receptors in the tachykinin neurokinin-1 system--mutational analysis of intracellular loop 3

Several membrane proteins have been functionally expressed from non-covalently coupled, contiguous segments especially with the split-site located between natural domains. Experiments using such 'split-proteins' were here performed in the tachykinin neurokinin-1 (NK1) receptor with co-expression of contiguous segments with split-sites positioned in various intracellular and extracellular loops. The construct where the split-site was located in intracellular loop 3 gave a reasonable expression level of substance-P-binding sites, i.e. 12% of wild-type expression. Of the other split-receptors tested, only the one with the split-site located just outside transmembrane (TM) segment-V gave any detectable substance P binding, which however only was 1% of the wild-type expression level. The construct with the split-site located in intracellular loop 3 bound all of the tested peptide agonists and non-peptide antagonists with normal affinity and was able to stimulate inositol phosphate turnover with a normal EC50 for substance P and an Emax according to the expression level. When intracellular loop 3 was either extended with 112 amino acid residues derived from the muscarine M2 receptor or, when major parts of the loop were deleted in the non-split NK1 receptor, the affinity for neither substance P nor for the prototype nonpeptide antagonist, CP96,345 was affected, yet an increase in EC50 for substance P was observed. Also in the split-receptor, most of intracellular loop 3 could be substituted or even deleted without affecting ligand affinity, although a decreased expression level was observed in constructs having major deletions. It is concluded, that the NK1 receptor is preferentially reconstituted by co-expression of a putative A-domain including TM-I-V and a B-domain including TM-VI and -VII. It is suggested that a number of rhodopsin-like 7TM receptors may function as two-domain structures based on the finding that a network of short loops has been highly conserved within each of the putative domains and, that these domains are separated by a relatively long and in respect of length poorly conserved loop, i.e. intracellular loop 3.     

A computerised adaptometer

The hippocampal EEG power spectra of rabbits were analyzed to clarify the relationship between the theta-wave and emotionality. The relative power of T2 (6.0-7.9 Hz)/T1 (4.0-5.9 Hz) represented the index of theta-wave change. Emotional excitement (produced with novelty stress or methamphetamine) or suppression (produced with restraint stress or reserpine) increased or decreased T2/T1 ratios within around +/- 1 Hz changes. Furthermore, the imaging patterns of the peak feature make possible detailed characterization of emotional states. These results suggest that the hippocampus finely adjusts the theta-wave on a +/- 1 Hz level, with a fine balance of voltage, in response to the emotional activity.     

Superior temporal gyrus and the course of early schizophrenia: progressive, static, or reversible?

Accumulating evidence suggests alterations in brain structure, especially in the prefrontal and temporal cortex, in schizophrenia. Previous studies examining the progression of brain structural alterations in schizophrenia have led to conflicting results. Morphometric studies of the superior temporal gyrus (STG) volumes were conducted in a series of neuroleptic-naive first-episode schizophrenic patients, non-schizophrenic first-episode psychotic patients, and matched healthy controls. Three-dimensional MRI scans were carried out in these subjects before and after one year of treatment. Volume reductions were seen at baseline in the left superior temporal gyrus (adjusted for intracranial volume) in both of the patient groups. Pretreatment illness duration was inversely related to the volume of the left superior temporal gyrus; this relation was confined to males. One-year follow-up MRI investigations in a smaller subset of patients suggested that the STG volume reductions may be reversible. No significant changes were noted in the STG volumes in matched healthy controls who were also scanned at baseline as well as at one-year follow-up. These findings have implications for understanding the nature of the neuropathological processes in early schizophrenia, as well as the potential impact of early treatment.     

Both lobes of the soluble receptor of the periplasmic histidine permease, an ABC transporter (traffic ATPase), interact with the membrane-bound complex. Effect of different ligands and consequences for the mechanism of action

The histidine permease of Salmonella typhimurium is an ABC transporter (traffic ATPase). The liganded soluble receptor, the histidine-binding protein HisJ, interacts with the membrane-bound complex HisQMP2 and stimulates its ATPase activity, which results in histidine translocation. In this study, we utilized HisJ proteins with mutations in either of the two lobes and wild type HisJ liganded with different substrates to show that each lobe carries an interaction site and that both lobes are involved in inducing (stimulating) the ATPase activity. We suggest that the spatial relationship between the lobes is one of the factors recognized by the membrane-bound complex in dictating the efficiency of the induction signal and of translocation. Several of the key residues involved have been identified. In addition, using constitutive ATPase mutants, we show that the binding protein provides some additional essential function(s) in translocation that is independent of the stimulation of ATP hydrolysis, and one possible mechanism is proposed, which includes the notion that liganded HisJ has different optimal conformations for signaling and for translocation.     

Comparison of pneumatic retinopexy and scleral buckling in the management of primary rhegmatogenous retinal detachment. Southern Wisconsin Pneumatic Retinopexy Study Group

PURPOSE: To compare pneumatic retinopexy and scleral buckling for repair of primary rhegmatogenous retinal detachment with respect to visual outcome, single-procedure reattachment rate, and development of proliferative vitreoretinopathy. METHODS: A consecutive series of eyes initially treated with pneumatic retinopexy (n = 56) between March 1986 and February 1996 were compared with a selected group of eyes treated with scleral buckling (n = 86) with similar location and distribution of retinal breaks and absence of proliferative vitreoretinopathy. A regression model was developed to adjust for underlying differences between treatment groups, resulting in a cohort of 50 eyes in each group for final comparison. A minimum follow-up of 6 months was obtained. RESULTS: Single-procedure reattachment rate was significantly higher for scleral buckle eyes (42 of 50 eyes, 84%) than for pneumatic retinopexy eyes (31 of 50 eyes, 62%; P < or = .01). Correspondingly, reoperation rate was significantly higher for pneumatic retinopexy eyes (19 of 50 eyes, 38%) than for scleral buckle eyes (7 of 50 eyes, 14%; P < or = .01). Multiple regression analysis evaluating perioperative factors demonstrated that the use of pneumatic retinopexy was the sole factor predictive of retinal detachment after a single procedure (relative odds = 2.20, P = .02). Final reattachment rate, after reoperations, was 98% (49 of 50 eyes) in each group. Except for nonphakic eyes, final visual outcome and rate of postoperative proliferative vitreoretinopathy development did not differ significantly between the two procedures. CONCLUSIONS: In phakic eyes, pneumatic retinopexy was associated with a significantly higher reoperation rate than scleral buckling, but resulted in equivalent final visual outcome and reattachment rate after reoperations. If used, it must be incorporated into a strategy in which patient and physician are prepared for a greater chance of reoperation compared to initial management with scleral buckling.     

Perspectives of patients with terminal renal failure: quality of life and psychological adjustment before and in the first year after heart transplantation

This prospective study was designed to compare quality of life, life satisfaction, and subjective ratings of health before and at variable time intervals after heart transplantation (HTx). 175 patients were included between February 1994 and December 1997. Every six months before and 1 1/2, 3, 6, and 12 months after HTx, they received the following standardized and validated questionnaires: German SF 36, heart failure and specific transplant symptom list, global quality of life assessment, Munich life quality dimension list, expected/experienced life changes after HTx. Inclusion criteria were the acceptance of the patient on the waiting list for HTx, good command of the German language, and a minimum age of 18 years. During data evaluation, median (Me), mean (M), and standard deviation (SD) were created from individual parameters. Quality of life was rated as very poor by 84% of patients with congestive heart failure. Only 6 weeks after HTx, 74% rated their quality of life as significantly better. Before HTx 80% were very unsatisfied about their health status and 87% about physical performance. Six weeks after HTx, this parameter improved significantly and 76% were very satisfied about their health status and 50% about physical performance. While somatic changes expected before HTx corresponded well with experienced ones, psychological improvements were smaller than expected, but one year after HTx they were significant (before: M = 3.66; SD = 0.9; Range (R) = 3.78 vs 12 months postop: M = 4.61; SD = 0.6; R = 2.67; p < 0.05). Quality of life correlated before HTx best with subjectively rated health (r = 0.61, p < 0.01) and 6 months after with satisfaction about health status (r = 0.76, p < 0.01). Only in 25% were expected improvements fulfilled regarding sexual activity/satisfaction, professional situation, and recreational activities. 90% of post-transplant patients reported physical complaints, most by effects of immunsuppression, but were coping well. The study shows that already 6 weeks after successful HTx all quality of life parameters improved significantly. Despite some unfulfilled expectations and complaints, the postoperative life situation of HTx patients appeared significantly improved.