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Rapid Drop (rapid + drop)
Selected AbstractsNerve growth factor increases airway responses and decreases levels of exhaled nitric oxide during histamine challenge in an in vivo guinea-pig modelACTA PHYSIOLOGICA, Issue 2 2001S. G. Friberg There is a growing body of evidence supporting the idea that nerve growth factor (NGF) may be involved in the development of asthma-associated symptoms, such as airway hyper-responsiveness. Increased levels of NGF have recently been described in serum and in the airways of asthmatics. We have examined whether exhaled nitric oxide (NO) levels might be altered during the increased airway responses upon NGF treatment in guinea-pigs in vivo. Intravenous (i.v.) administration of histamine normally elicits a rapid peak in insufflation pressure (IP) and in exhaled NO, followed by a period of decreased concentrations of exhaled NO. Anaesthetized guinea-pigs were pre-treated intravenously with either saline, 4 or 80 ng kg,1 NGF 30 min before i.v. challenge with 16 ,g kg,1 histamine. At 80 ng kg,1 NGF significantly enhanced the airway obstruction caused by histamine, whereas the peak acute increase in exhaled NO was not enhanced. Following the increase, came a rapid drop, an effect enforced in the NGF treated animals. Subsequently, the time to return to 90% of resting exhaled NO was increased, from 12 min in saline-treated animals to 48 min in NGF-treated animals. Our data confirm that NGF can enhance airway responses to histamine. Moreover, our study shows a decrease in exhaled NO following a histamine challenge, an effect enhanced by NGF. A reduced ability to release exhaled NO may be a mechanism for increased airway responses during elevated NGF levels. The interaction between NGF and airway NO formation, and its relation to airway responses, merit further investigation. [source] Growth of children on the ketogenic dietDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 12 2002Eileen P G Vining MD This is a prospective cohort study of 237 children (130 males, 107 females) placed on the ketogenic diet for control of intractable epilepsy (mean age at starting diet 3 years 8 months; age range 2 months to 9 years 10 months); average length of follow-up was 308 days. There were 133 children on the diet at 1 year and 76 at 2 years. Height and weight measurements were converted into age- and sex-appropriate z scores. There was a rapid drop in weight z scores in the first 3 months. After this initial period, the weight z score remained constant in children who started the diet below the median weight for their age and sex, although z scores continued to decrease in children starting above the median. There was a small decrease in height z scores in the first 6 months (<0.5); however, there were larger changes by 2 years. There was no difference based on sex for either height or weight. The ketogenic diet generally provides sufficient nutrition to maintain growth within normal parameters over a defined period. Very young children grow poorly on the diet and should be followed-up carefully over long periods of use. [source] The Impact of Uncertainty ShocksECONOMETRICA, Issue 3 2009Nicholas Bloom Uncertainty appears to jump up after major shocks like the Cuban Missile crisis, the assassination of JFK, the OPEC I oil-price shock, and the 9/11 terrorist attacks. This paper offers a structural framework to analyze the impact of these uncertainty shocks. I build a model with a time-varying second moment, which is numerically solved and estimated using firm-level data. The parameterized model is then used to simulate a macro uncertainty shock, which produces a rapid drop and rebound in aggregate output and employment. This occurs because higher uncertainty causes firms to temporarily pause their investment and hiring. Productivity growth also falls because this pause in activity freezes reallocation across units. In the medium term the increased volatility from the shock induces an overshoot in output, employment, and productivity. Thus, uncertainty shocks generate short sharp recessions and recoveries. This simulated impact of an uncertainty shock is compared to vector autoregression estimations on actual data, showing a good match in both magnitude and timing. The paper also jointly estimates labor and capital adjustment costs (both convex and nonconvex). Ignoring capital adjustment costs is shown to lead to substantial bias, while ignoring labor adjustment costs does not. [source] Role of the plasma membrane leaflets in drug uptake and multidrug resistanceFEBS JOURNAL, Issue 5 2010Hagar Katzir The present study aimed to investigate the role played by the leaflets of the plasma membrane in the uptake of drugs into cells and in their extrusion by P-glycoprotein and multidrug resistance-associated protein 1. Drug accumulation was monitored by fluorescence resonance energy transfer from trimethylammonium-diphenyl-hexatriene (TMA-DPH) located at the outer leaflet to a rhodamine analog. Uptake of dye into cells whose mitochondria had been inactivated was displayed as two phases of TMA-DPH fluorescence quenching. The initial phase comprised a rapid drop in fluorescence that was neither affected by cooling the cells on ice, nor by activity of mitochondria or ABC transporters. This phase reflects the association of dye with the outer leaflet of the plasma membrane. The subsequent phase of TMA-DPH fluorescence quenching occurred in drug-sensitive cell lines with a half-life in the range 20,40 s. The second phase of fluorescence quenching was abolished by incubation of the cells on ice and was transiently inhibited in cells with active mitochondria. Thus, the second phase of fluorescence quenching reflects the accumulation of dye in the cytoplasmic leaflet of the plasma membrane, presumably as a result of flip-flop of dye across the plasma membrane and slow diffusion from the inner leaflet into the cells. Whereas activity of P-glycoprotein prevented the second phase of fluorescence quenching, the activity of multidrug resistance-associated protein 1 had no effect on this phase. Thus, P-glycoprotein appears to pump rhodamines from the cytoplasmic leaflet either to the outer leaflet or to the outer medium. [source] Application of a coil-type TDR probe for measuring the volumetric water content in weathered granitic bedrockHYDROLOGICAL PROCESSES, Issue 6 2008Shin'ya Katsura Abstract As a first step toward describing water flow processes in bedrock, a coil-type time domain reflectometry (TDR) probe capable of measuring volumetric water content, ,, in weathered bedrock at three depths was prepared. Because the coil-type TDR probe is large in diameter (19 mm), it can be installed even in highly weathered bedrock more easily and appropriately than conventional TDR probes that consists of two or three rods of small diameter (5-8 mm). The probe calibrations suggest that the values measured by the probe are very sensitive to changes in ,. Using the calibrated probe together with commercially available profile soil moisture sensors, the , profile was monitored for 1 year. Even rainfall events with relatively small cumulative rainfall of 15 mm increased the bedrock ,, and the increments were comparable to those in the soil. After the end of the rainfall events, the bedrock , displayed a more rapid drop than the soil, and varied little during the period of no rainfall. The water storage showed similar tendencies. These observations suggest that the bedrock , is controlled by clearly distinguishable macropores and micropores within the bedrock. It is concluded that the coil-type TDR probe is very effective in determining , in weathered bedrock, and that bedrock, conventionally defined by conducting cone penetration tests and treated as impermeable, does conduct and hold substantial amounts of water, and therefore contribute greatly to hydrological processes in headwater catchments. Copyright © 2007 John Wiley & Sons, Ltd. [source] Inter-ocean dispersal is an important mechanism in the zoogeography of hakes (Pisces: Merluccius spp.)JOURNAL OF BIOGEOGRAPHY, Issue 6 2001W. Stewart Grant Aim To present new genetic data and to review available published genetic data that bear on the phylogeny of hakes in the genus Merluccius. To construct a zoogeographical model from a summary phylogenetic tree with dated nodes. To search for an explanation of antitropical distributions in hakes. To assess peripheral isolate, centrifugal and vicariance models of speciation in view of the molecular phylogeny and zoogeography of hakes. Locations Northern and southern Atlantic Ocean, eastern Pacific Ocean, South Pacific Ocean. Methods Electrophoretic analysis of 20 allozyme loci in 10 species of hakes. Phylogenetic tree construction with parsimony and bootstrap methods. Reanalysis of previous genetic data. Analysis of zoogeographical patterns with geographical distributions of molecular genetic markers. Results Phylogenetic analyses of new and previous allozyme data and previous mitochondrial DNA data indicate a deep genetic partition between Old- and New-World hakes with genetic distances corresponding to 10,15 Myr of separation. This time marks a widening rift between Europe and North America and a rapid drop in ocean temperatures that subdivided an ancestral population of North Atlantic hake. Two Old-World clades spanning the equator include pairs of sister taxa separated by tropical waters. Divergence times between these pairs of sister-taxa variously date to the early Pliocene and late Pleistocene. Amongst New-World hakes, pairs of sister taxa are separated by equatorial waters, by the Southern Ocean, and by the Panama Isthmus. These genetic separations reflect isolation by the rise of the Isthmus 3,4 Ma and by Pliocene and Pleistocene dispersals. Pairs of species occurring in sympatry or parapatry in six regions do not reflect sister-species relationships, but appear to reflect allopatric divergence and back dispersals of descendent species. Some geographically isolated regional populations originating within the last few hundreds of thousands of years merit subspecies designations. Conclusions Vicariance from tectonic movement of continental plates or ridge formation cannot account for the disjunct distributions of most hake sister taxa. Molecular genetic divergences place the origin of most hake species diversity in the last 2,3 Myr, a period of negligible tectonic activity. Distributions of many hake species appear to have resulted from dispersals and back dispersals across both warm equatorial waters and cool waters in the Southern Ocean, driven by oscillations in climate and ocean temperatures. Genetic and ecological divergence prevents hybridization and competitive exclusion between sympatric species pairs in six regions. Sister-taxa relationships and estimates of divergence are consistent with the modified peripheral isolate model of speciation in which vicariances, range expansions and contractions, dispersals and founder events lead to isolated populations that subsequently diverge to form new species. [source] THE GEOLOGY AND HYDROCARBON HABITAT OF THE SARIR SANDSTONE, SE SIRT BASIN, LIBYAJOURNAL OF PETROLEUM GEOLOGY, Issue 2 2000G. Ambrose The Jurassic , Lower Cretaceous Sarir Sandstone Cformerly known as the Nubian Sandstone) in the SE Sirt Basin is composed of four members which can be correlated regionally using a lithostratigraphic framework. These synrift sandstones unconformably overlie a little known pre-rift succession, and are in turn unconformably overlain by post-rift marine shales of Late Cretaceous age. Within the Sarir Sandstone are two sandstone-dominated members, each reflecting a rapid drop in base level, which are important oil reservoirs in the study area. Between these sandstones are thick shales of continental origin which define the architecture of the reservoir units. This four-fold lithostratigraphic subdivision of the Sarir Sandstone contrasts with previous schemes which generally only recognised three members. The sandstones below the top-Sarir unconformity host in excess of 20 billion barrels of oil in-place. The dominant traps are structural (e.g. Sarir C field), stratigraphic (e.g. Messla field), hanging-wall fault plays (e.g. UU1,65 field) and horst-block plays (e.g. Calanscio field). Three Sarir petroleum systems are recognised in the SE Sirt Basin. The most significant relies on post-rift (Upper Cretaceous) shales, which act as both source and seal. The Variegated Shale Member of the Sarir Sandstone may also provide source and seal; while a third, conceptual petroleum system requires generation of non-marine oils from pre-rift (?Triassic) source rocks in the axis of the Sarir Trough. The intrabasinal Messla High forms a relatively rigid block at the intersection of two rift trends, around which stress vectors were deflected during deposition of the syn-rift Sarir Sandstone. Adjacent troughs accommodated thick, post-rift shale successions which comprise excellent source rocks. Palaeogene subsidence facilitated oil generation, and the Messla High was a focus for oil migration. Wrenching on master faults with associated shale smear has facilitated fault seal and the retention of hydrocarbons. In the Calanscio area, transpressional faulting has resulted in structural inversion with oil entrapment in "pop-up" horst blocks. Elsewhere, transtensional faulting has resulted in numerous fault-dependent traps which, in combination with stratigraphic and truncation plays, will provide the focus for future exploration. [source] Novel biopolymers as implant matrix for the delivery of ciprofloxacin: Biocompatibility, degradation, and in vitro antibiotic releaseJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2007Suniket V. Fulzele Abstract The purpose of this study was to investigate the in vitro,in vivo degradation and tissue compatibility of three novel biopolymers viz. polymerized rosin (PR), glycerol ester of polymerized rosin (GPR) and pentaerythritol ester of polymerized rosin (PPR) and study their potential as implant matrix for the delivery of ciprofloxacin hydrochloride. Free films of polymers were used for in vitro degradation in PBS (pH 7.4) and in vivo in rat subcutaneous model. Sample weight loss, molecular weight decline, and morphological changes were analyzed after periodic intervals (30, 60, and 90 days) to monitor the degradation profile. Biocompatibility was evaluated by examination of the inflammatory tissue response to the implanted films on postoperative days 7, 14, 21, and 28. Furthermore, direct compression of dry blends of various polymer matrices with 20%, 30%, and 40% w/w drug loading was performed to investigate their potential for implant systems. The implants were characterized in terms of porosity and ciprofloxacin release. Biopolymer films showed slow rate of degradation, in vivo rate being faster on comparative basis. Heterogeneous bulk degradation was evident with the esterified products showing faster rates than PR. Morphologically all the films were stiff and intact with no significant difference in their appearance. The percent weight remaining in vivo was 90.70,±,6.2, 85.59,±,5.8, and 75.56,±,4.8 for PR, GPR, and PPR films respectively. Initial rapid drop in Mw was demonstrated with nearly 20.0% and 30.0% decline within 30 days followed by a steady decline to nearly 40.0% and 50.0% within 90 days following in vitro and in vivo degradation respectively. Biocompatibility demonstrated by acute and subacute tissue reactions showed minimal inflammatory reactions with prominent fibrous encapsulation and absence of necrosis demonstrating good tissue compatibility to the extent evaluated. All implants showed erosion and increase in porosity that affected the drug release. Increase in drug loading significantly altered the ciprofloxacin release in extended dissolution studies. PPR produced drug release >90% over a period of 90 days promising its utility in implant systems. The results demonstrated the utility of novel film forming biopolymers as implant matrix for controlled/sustained drug delivery with excellent biocompatibility characteristics. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96:132,144, 2007 [source] Histopathology and Immunophenotype of the Spleen During Acute Antibody-Mediated RejectionAMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2010B. Kaplan Splenectomy has been reported to have a beneficial effect in treating Acute antibody-mediated rejection (ABMR). This reason for this often rapid and profound beneficial effect is not readily apparent from what is known about normal splenic immunoarchitecture. While the spleen is rich in mature B cells, it has not been noted to be a repository for direct antibody-secreting cells. We present a case of a Native American female who received a renal transplant and developed a severe episode of ABMR. The patient was initially refractory to both plasmapheresis and IVIG. The patient underwent an emergent splenectomy with almost immediate improvement in her renal function and a rapid drop in her DR51 antibodies. Immunohistochemical stains of the spleen demonstrated abundant clusters of CD138+ plasma cells (>10% CD138 cells as opposed to 1% CD138 cells as seen in traumatic controls). Though this is a single case, these findings offer a rationale for the rapid ameliorative effect of splenectomy in cases of antibody rejection. It is possible that the spleen during times of excessive antigenic stress may rapidly turn over B cells to active antibody-secreting cells or serve as a reservoir for these cells produced at other sites. [source] Erythropoietin production rate in phlebotomy-induced acute anemiaBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 9 2004N.H. Al-Huniti Abstract Objective. To estimate the rate of erythropoietin (EPO) production under physiological, conditions and to examine the regulatory mechanism of EPO production in response to acute phlebotomy-induced anemia. Methods. Six sheep each underwent two phlebotomies in which the hemoglobin (Hb) was reduced to 3,4 g/dl over 4,5 h. The EPO plasma level, reticulocytes, Hb and EPO clearance were followed by frequent blood sampling. The EPO production rate was determined by a semi-parametric method based on a disposition decomposition analysis that accounts for the nonlinear disposition kinetics of EPO and corrects for time-dependent changes in the clearance. Results. The controlled drop in hemoglobin resulted in an abrupt increase in the plasma EPO concentration (peak level 812 ± 40 mU/ml, mean ± CV%) that was followed by a rapid drop 2,4 days after the phlebotomy at a time when the sheep were still anemic (Hb = 4.3 ± 16 g/dl). The EPO production rate at baseline was 43 ± 52 U/day/kg and the amounts of EPO produced over an 8 day period resulting from the first and second phlebotomy were 2927 ± 40 U/kg and 3012 ± 31 U/kg, respectively. Conclusions. The rapid reduction in the EPO plasma level observed 2,4 days following the phlebotomy cannot be explained solely by the increase in EPO clearance but also by a reduction in EPO production. Copyright © 2004 John Wiley & Sons, Ltd. [source] Chronological aspects of ultrasonic, hormonal, and other indirect indices of ovulationBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 8 2001René Ecochard Objective To improve prediction of ovulation in normal cycles. Design Collection of women's characteristics and their menstrual cycles. Monitoring and analysis of time relationships between several indicators of ovulation: transvaginal ultrasonography, cervical mucus, basal body temperature, urinary luteinising hormone, and ratio of urinary oestrogen to progesterone metabolites. Setting Each of eight natural family planning clinics was to study 12 women for at least three cycles. Population One hundred and seven normally fertile and cycling women aged 18 to 45. Methods Daily measurements of urinary luteinising hormone, follicle stimulating hormone, oestrone-3-glucuronide and pregnanediol-3, -glucuronide. Basal body temperature recording and cervical mucus checking. Transvaginal ultrasound examination of the ovaries. Main outcome measures Delays between the expected day of ovulation according to the luteinising hormone peak or to ultrasound evidence and the expected days according to the other indices of ovulation. Results Ultrasonography was able to show evidence of ovulation in 283 out of 326 cycles. The average time lag between luteinising hormone peak and ultrasound evidence was less than one day (+0.46) but premature and late luteinising hormone-expected date of ovulation were observed in nearly 10% and 23% of cycles, respectively. Basal body temperature rise was observed in 98% of cycles. Cervical mucus peak symptom, rapid drop in the ratio of urinary metabolites, and luteinising hormone initial rise were all close to ultrasonographic evidence in more than 72% of cycles. Conclusions For accuracy and practical reasons, the cervical mucus peak symptom, the ratio of urinary metabolites and luteinising hormone initial rise might be better indices of ovulation than the luteinising hormone peak. [source] | |||||||||||||