Distribution of alpha 1A, alpha 1B and alpha 1E voltage-dependent calcium channel subunits in the human hippocampus and parahippocampal gyrus

The distribution of voltage-dependent calcium channel subunits in the central nervous system may provide information about the function of these channels. The present study examined the distribution of three alpha-1 subunits, alpha 1A, alpha 1B and alpha 1E, in the normal human hippocampal formation and parahippocampal gyrus using the techniques of in situ hybridization and immunocytochemistry. All three subunit mRNAs appeared to be similarly localized, with high levels of expression in the dentate granule and CA pyramidal layer. At the protein level, alpha 1A, alpha 1B and alpha 1E subunits were differentially localized. In general, alpha 1A-immunoreactivity was most intense in cell bodies and dendritic processes, including dentate granule cells, CA3 pyramidal cells and entorhinal cortex pre-alpha and pri-alpha cells. The alpha 1B antibody exhibited relatively weak staining of cell bodies but stronger staining of neuropil, especially in certain regions of high synaptic density such as the polymorphic layer of the dentate gyrus and the stratum lucidum and radiatum of the CA regions. The alpha 1E staining pattern shared features in common with both alpha 1A and alpha 1B, with strong immunoreactivity in dentate granule, CA3 pyramidal and entorhinal cortex pri-alpha cells, as well as staining of the CA3 stratum lucidum. These findings suggest regions in which particular subunits may be involved in synaptic communication. For example, comparison of alpha 1B and alpha 1E staining in the CA3 stratum lucidum with calbindin-immuno-reactivity suggested that these two calcium channels subunits may be localized presynaptically in mossy fibre terminals and therefore may be involved in neurotransmitter release from these terminals.     

Pre‐natal and post‐natal exposure to pet ownership and lung function in children: The Seven Northeastern Cities Study

To evaluate the association between pre‐natal and post‐natal exposure to pet ownership and lung function in children, a cross‐sectional study named Seven Northeastern Cities (SNEC) study was conducted. In this study, children's lung function including the forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), maximal mid‐expiratory flow (MMEF), and peak expiratory flow (PEF) were measured by spirometers, and pet ownership situations were collected by questionnaire. Analyzed by multiple logistic regression and generalized linear modeling, we found that for all subjects, pet exposure in the first 2 years of life was significantly associated with lung function impairment of FVC<85% predicted (adjusted odds ratio [aOR]=1.28; 95% confidence interval [CI]: 1.01, 1.63). For current pet exposure, the increased odds of lung function impairment ranged from 35% (aOR=1.35; 95%CI: 1.12, 1.62) for FVC<85% predicted to 57% (aOR=1.57; 95%CI: 1.29, 1.93) for FEV₁<85% predicted. The in utero exposure was not related to lung function impairment. Compared with other pets, higher odds were observed among children with dogs. When stratified by gender, girls with current pet exposure were more likely to have lung function impairment than boys. It implies self‐reported exposures to pets were negatively associated with lung function among the children under study.     

Symbol-by-symbol MAP demodulation of CPM and PSK signals onRayleigh flat-fading channels

Demodulation using the symbol-by-symbol maximum a posteriori probability (MAP) algorithm is presented. The algorithm is derived for the case of continuous phase modulation (CPM) signals transmitted over Rayleigh flat-fading channels, and a corresponding receiver structure is specified. It is shown that the MAP algorithm requires computing, for each trellis branch, the sum of the products of the weights of all paths through the trellis which pass through that branch, and that this generic computational problem can be solved efficiently by an approach that uses a forward and backward recursion through the trellis. Simulation results are presented which show both the hard and soft decision performance of the MAP receiver to be robust, even in the presence of fade rates of up to 30% of the symbol rate. The application of the receiver concept to phase-shift keying (PSK) signals is also discussed, and then evaluated via simulation. The concept of joint demodulation and decoding using iterative processing techniques is introduced. It is shown that the MAP receiver is well suited for iterative processing applications due to its use of a priori symbol probabilities and its production of optimal soft decisions. Simulation results for the reception of quaternary PSK (QPSK) show that the bit error rate (BER) performance of the iterative MAP receiver can approach that of a receiver operating with perfect knowledge of the fading process     

Ascorbate enhances iron uptake into intestinal cells through formation of a FeCl3–ascorbate complex

It has been well documented that ascorbate enhances iron uptake, with a proposed mechanism based on reduction to the more absorbable ferrous form. We have performed a study on the effects of ascorbate on ferric iron uptake in the human epithelial Caco-2 cell-line. Ascorbate increased uptake in a concentration-dependent manner with a significant difference between iron uptake and reduction. Uptake kinetics are characteristic of a non-essential activator and the formation of an Fe³⁺–ascorbate complex. This investigation provides evidence that ascorbate enhances the apical uptake of ferric iron into Caco-2 cells through the formation of a Fe³⁺–ascorbate complex.     

Cerebral metabolic effects of sequential periods of hypothermic circulatory arrest

During repair of congenital heart defects, extended periods of hypothermic circulatory arrest (CA) have been shown to cause short-term cerebral metabolic and flow abnormalities as well as long-term neuropsychologic dysfunction. Occasionally, a second period of CA is required during the same operative setting to revise a complicated repair. However, the metabolic effects of two consecutive periods of CA on the brain are unclear. In this study, we compared the recovery of cerebral metabolism after 60 minutes of CA with that after two sequential 30-minute periods of CA separated by a brief period of rewarming (30'SEQ). Fifteen neonatal piglets (2 to 3 kg) were placed on cardiopulmonary bypass at 100 mL.kg-1 x min-1 and cooled to 18 degrees C. Each animal then underwent either 60 minutes of uninterrupted cardiopulmonary bypass at 18 degrees C, 60 minutes of CA, or two 30-minute periods of CA separated by a brief period of rewarming. After these experimental periods, animals were rewarmed to 37 degrees C and weaned from cardiopulmonary bypass. Data were obtained before cardiopulmonary bypass and after cardiopulmonary bypass at 37 degrees C and included measurements of cerebral blood flow by xenon 133 clearance, arterial and sagittal sinus blood gases, and cerebral metabolism (mL O2.100 g-1 x min-1). Our results demonstrated that acute recovery of cerebral metabolism was significantly impaired after 60 minutes of CA and that recovery of cerebral metabolism after two sequential 30-minute periods of CA was significantly better than after 60 minutes of continuous CA.(ABSTRACT TRUNCATED AT 250 WORDS)     

Space-time coding in mobile Satellite communications using dual-polarized channels

The use of dual-orthogonal polarization (horizontal/vertical or circular right-hand/left-hand polarizations) can increase the rate of transmission of satellite communication systems by a factor of two. However, the cross polar discriminations (XPDs) of the satellite and earth station antennas may be large enough to severely interfere between the two polarizations. In this paper, we investigate the use of space-time coding techniques in satellite-land mobile systems using dual-polarized transmit and receive antennas. In particular, we show that we can achieve significant gains by using layered space-time coding concepts and iterative detection and decoding receivers in communications systems employing polarization diversity channels in the presence of line-of-sight components.     

An evaluation of vesical urodynamics before renal transplantation and its effect on renal allograft function and survival

This prospective study investigated the urodynamics of the urinary bladder prior to renal transplantation in 57 patients and related this to graft function and transplantation outcome. The study demonstrated a clear deterioration in the pretransplant urodynamic characteristics in all subgroups, with male patients in the hemodialysis group (HD) showing a more substantial decline: 1st sensation volume (ml) in male HD patients = 112 (120) vs. 171 (173) in male CAPD patients, P < 0.05; and corresponding average flow rate for same groups 3 (3) ml/sec vs. 5 (5) ml/sec, P < 0.05. Figures are median (interquartile range). We have identified a subgroup of patients with a small bladder capacity (less than 100 ml) who have a reduced graft survival (55% vs. 92% for bladders larger than 100 ml at 2 years) apparently unrelated to immunological processes.     

Synthesis of the four isomers of 4-aminopyrrolidine-2,4-dicarboxylate: identification of a potent, highly selective, and systemically-active agonist for metabotropic glutamate receptors negatively coupled to adenylate cyclase

The four isomers of 4-aminopyrrolidine-2,4-dicarboxylate (APDC) were prepared and evaluated for their effects at glutamate receptors in vitro. (2R,4R)-APDC (2a), an aza analog of the nonselective mGluR agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylate (1S,3R)-ACPD, 1), was found to possess relatively high affinity for metabotropic glutamate receptors (mGluRs) (ACPD-sensitive [3H]glutamate binding IC50 = 6.49 +/- 1.21 microM) with no effects on radioligand binding to NMDA, AMPA, or kainate receptors up to 100 microM. None of the other APDC isomers showed significant mGluR binding affinity, indicating that this interaction is highly stereospecific. Both 1 and 2a were effective in decreasing forskolin-stimulated cAMP formation in the adult rat cerebral cortex (EC50 = 8.17 +/- 2.21 microM for 1; EC50 = 14.51 +/- 5.54 microM for 2a); however, while 1 was also effective in stimulating basal tritiated inositol monophosphate production in the neonatal rat cerebral cortex (EC50 = 27.7 +/- 5.2 microM), 2a (up to 100 microM) was ineffective in stimulating phosphoinositide hydrolysis in this tissue preparation, further supporting our previous observations that 2a is a highly selective agonist for mGluRs negatively coupled to adenylate cyclase. Microelectrophoretic application of either 1 or 2a to intact rat spinal neurons produced an augmentation of AMPA-induced excitation (95 +/- 10% increase for 1, 52 +/- 6% increase for 2a). Intracerebral injection of 1 (400 nmol) produced characteristic limbic seizures in mice which are not mimicked by 2a (200-1600 nmol, ic). However, the limbic seizures induced by 1 were blocked by systemically administered 2a in a dose-dependent manner (EC50 = 271 mg/kg, ip). It is concluded that (2R,4R)-APDC (2a) is a highly selective, systemically-active agonist of mGluRs negatively coupled to adenylate cyclase and that selective activation of these receptors in vivo can result in anticonvulsant effects.