Short term performance evaluation of a perfluorocopolymer coated gas exchanger for arteriovenous CO2 removal

A new perfluorocopolymer coating for micropore hollow fiber gas exchangers was developed to improve gas exchange, reduce plasma leakage, and reduce blood-surface interactions. The present authors evaluated gas exchanger performance using this new coating in a prospective, randomized, controlled, unblinded, large animal model of CO2 retention. Adult sheep (30-40 kg), under general anesthesia, underwent cannulation of the carotid artery (12 F) and jugular vein (14 F). The perfluorocopolymer coated (n = 5) and uncoated (n = 5) gas exchangers were attached to an arteriovenous CO2 removal (AVCO2R) circuit. Blood gases, CO2 removal, and hemodynamics were monitored throughout the 6 hour study. Average CO2 removal was 107.6 +/- 15.6 ml/min (coated) vs. 93.0 +/- 13.9 ml/min (uncoated; p < 0.01). PaCO2 and CO2 removal for both coated and uncoated did not deteriorate significantly over the study. Average AVCO2R blood flow was 1,130 +/- 25 ml/min (coated) versus 1,101 +/- 79 ml/min (uncoated; p = not significant). Likewise, cardiac output and AVCO2R blood flow did not change over the duration of the study. No significant differences in the pressure gradient or resistance between devices (coated, 6.89 +/- 1.14 mm Hg/L/min; uncoated, 6.42 +/- 0.23 mm Hg/L/min) was noted. The authors concluded that the new perfluorocopolymer coated gas exchanger improved CO2 removal without compromising hemodynamics in an acute performance evaluation.     

Total ovarian volume before human chorionic gonadotrophin administration for ovulation induction may predict the hyperstimulation syndrome

Total ovarian volumes were measured before the administrationof HCG in 42 women undergoing treatment for infertility by in-vitrofertilization (IVF) and embryo transfer and considered to havean exaggerated response to stimulation (>20 follicles). Sevenwomen who subsequently developed moderate or severe ovarianhyperstimulation syndrome (OHSS) (n = 7; group 1) were comparedwith 35 matched controls (five matched controls per case; n= 35; group 2) of similar age, number of follicles and durationof infertility who underwent follicular stimulation, oocyterecovery, in-vitro fertilization and embryo transfer duringthe same period but did not develop moderate or severe OHSS.The mean age, duration of infertility and total number of follicleswere similar but the mean total ovarian volume was significantlyhigher in the group of women who developed moderate or severeOHSS compared with controls (271.00 ± 87.00 versus 157.30± 54.20 ml; P < 0.01). We conclude that total ovarianvolume measured before HCG administration is higher in womenwho develop moderate or severe OHSS compared with controls andmay therefore be used as an additional parameter in the preventativestrategy for the ovarian hyperstimulation syndrome.     

Behavioural and ERP indices of response inhibition during a Stop-signal task in children with two subtypes of Attention-Deficit Hyperactivity Disorder.

Previous research has shown that children with Attention-Deficit Hyperactivity Disorder of the Combined Type (AD/HDcom) have problems with response inhibition, with poorer task performance and atypical inhibition-related ERPs relative to control subjects, while little is known about response inhibition in children with Attention-deficit Hyperactivity Disorder of the Predominantly Inattentive Type (AD/HDin). In this study children with AD/HDin (N=12), AD/HDcom (N=13) and age-matched controls (N=13) aged between 8 and 14 years completed a Stop-signal task, with visual Go and auditory Stop-signal stimuli, while EEG was recorded. The results indicated that the groups did not differ on any inhibitory task performance measure, but the AD/HD groups showed more errors of omission to Go stimuli than controls. ERPs to the visual Go stimuli differed between children with AD/HDin and controls (increased central N1 and N2, decreased central P2 and increased parietal P3), while the AD/HDcom group showed only minor scalp distribution differences for N2 and P3. The AD/HDin group showed amplitude differences from controls to Stop signals (larger central N1 and parietal P3; reduced midline N2) and did not show a Successful vs. Failed inhibition effect for P3. The AD/HDcom group showed reduced parietal P3 to Stop signals, with the Trial Type effect present for N2 but not P3. These data suggest that the apparent atypical inhibitory processing at N2 and P3 may stem, at least in part, from atypical early sensory/alerting processing of all stimuli in children with AD/HDin.     

The role of prolactin and testosterone in mediating seasonal differences in the self-grooming behavior of male meadow voles, Microtus pennsylvanicus

Self-grooming in response to the odors of conspecifics is a form of olfactory communication among meadow voles. The amount of time meadow voles spend self-grooming when they encounter the odors of conspecifics varies seasonally, with males targeting the odors of reproductively active females only during the breeding season. Other odor related behaviors in male voles such as odor preferences for conspecifics and the attractiveness of their odors to conspecifics vary seasonally as well. For male meadow voles, these behaviors are mediated by seasonal variations in testosterone (T) and prolactin (PRL) titers. The objective of this study was to determine whether seasonal differences in the amount of time male meadow voles self-groom in response to odors of conspecifics are mediated by seasonal rhythms in their circulating T and PRL titers. We tested the hypothesis that high titers of both T and PRL are necessary for reproductively active (long-photoperiod; LP) males and sufficient for reproductively quiescent (short-photoperiod; SP) male voles to spend more time self-grooming in response to odors of LP females than to those of other conspecifics. Results of this study demonstrate that high titers of PRL and T are necessary for LP male meadow vole to self-groom more in response to odors of LP females as compared to those of other conspecifics, but were not sufficient to induce SP males to preferentially self-groom to odors of LP females. The endocrine control of self-grooming by LP males appears to depend upon high titers of both PRL and T, which matches the endocrine mediation of other odor related behaviors in male voles. In contrast, the endocrine tissues that underlie self-grooming in SP male meadow voles appear to be refractory to the effects of LP-equivalent titers of PRL and T.     

Neural projections of the preoptic-suprachiasmatic region to the median eminence in the rat: A quantitative autoradiographic study

The possibility of a preferential distribution of projections from the preoptic-suprachiasmatic region (POA-Sch) to the median eminence in the male rat was studied using autoradiographic and computer procedures. A cocktail of [3H]leucine-[3H]proline was injected into the POA-Sch. Animals were killed after either 1, 4, or 24 h of incorporation time (IT). The number of silver grains per 25-micron square was counted throughout the median eminence. Squares with silver grain densities at or above the 75 percentile of the population for any given IT group were labeled as "concentrating areas." The distribution of these concentrating areas in median eminence tissue was analyzed utilizing univariate procedures. Visual inspection of the distribution of silver grain densities in a rostrocaudal fashion indicated the likelihood of uneven distribution; however, these differences were not statistically significant. In the dorsoventral plane, results indicated that the highest silver grain density was at 50 to 75 micron from the floor of the 3rd ventricle. Such distribution was apparent both ipsi- and contralateral to the injection site, but was greater on the ipsilateral side.     

Human multilineage progenitor cell sensitivity to 4-hydroperoxycyclophosphamide

This institution has documented consistent reconstitution of hematopoiesis in patients treated with marrow lethal chemoradiotherapy who are "rescued" by reinfusion of autologous cryopreserved marrow cells incubated with 4-hydroperoxycyclophosphamide (4-HC) for in vitro purging of occult tumor cells. After 4-HC incubation, the reinfusion marrow cells showed marked reduction in committed progenitor cell (BFU-E, CFU-GM) frequency, and often total absence of detectable progenitors, without significant loss of marrow reconstituting ability. Since BFU-E and CFU-GM assays did not predict marrow reconstituting ability after 4-HC incubation, we sought to determine whether multilineage progenitor cells (CFU-GEMM) might be more resistant to 4-HC incubation and therefore a more reliable predictive assay in this setting. We found that BFU-E, CFU-GM, and CFU-GEMM all show similar dose-related sensitivity to in vitro incubation with 4-HC and do not appear representative of the cell(s) responsible for marrow reconstitution.     

Electroconvulsive Therapy in Two Former Neurosurgical Patients: Skull Prosthesis and Ventricular Shunt

Electroconvulsive therapy (ECT) was successfully used to treat patients with prior neurosurgical history. The first patient had undergone surgery for a meningioma with subsequent insertion of a plate in the cranium. The second patient had a history of normal pressure hydrocephalus which was treated with a ventriculoperitoneal shunt procedure. Both patients received ECT and in both cases the presenting symptoms of depression abated. Treatment was considered both uneventful and successful.     

Maturational topography of the visual evoked potential in fetal lambs

The normal maturational course of the visual evoked potential (VEP) in human newborns and infants is well documented. Unfortunately, there is a paucity of data about VEP maturation in the normal preterm infant. Since this population is at risk to develop many abnormalities affecting the VEP (intraventricular hemorrhage, hydrocephalus, and retinopathy of prematurity), one must question whether such VEP data collected from this group is representative of normal maturation. To provide normative parametric developmental data we have been studying VEP development in fetal lambs. Six fetal lambs between 105 and 120 days gestational age were externalized and surgically instrumented with subcutaneous recording electrodes placed over the occipital and parietal regions. High-intensity light-emitting diodes (LEDs) externalized fiberoptic cables were secured adjacent to the orbit. from 108 to 141 days gestation, fetal VEPs were recorded in response to bright flash stimulation and the maturational topography was investigated.Over the occipital regions, the emergence of major positivities at P400 and P650 were observed beginning around 120 days gestation. Over the parietal area, the emergence of P200 and P500 components was observed by 128 days gestation. The latency-maturation functions revealed that the slope of the parietal function was steeper than the occipital counterpart, suggesting that the maturation of parietal neurons occurs at a faster rate than neuronal development in the occipital regions.     

Incidence and specificity of interference in two-site immunoassays

Using a modified "two-site" immunoradiometric assay, termed an "interference assay," we have demonstrated the occurrence of non-analyte antibody-binding substances in approximately 40% of serum samples. These substances multivalently bind antibodies from any of several species at a site other than the antigen-binding site. Using a two-site immunoradiometric assay for human choriogonadotropin, we have investigated their effect on analyte quantification. In this system these antibody-binding substances mimic the presence of analyte; when analyte is actually present, they can also cause over- or underestimates. Addition of excess nonspecific immunoglobulin from an appropriate species eliminates this interference. However, the amount of nonspecific immunoglobulin added to an assay system may not always be enough to block interference in all samples.