Increased abundance of frost mRNA during recovery from cold stress is not essential for cold tolerance in adult Drosophila melanogaster.

Frost (Fst) is a candidate gene associated with the response to cold in Drosophila melanogaster because Fst mRNA accumulation increases during recovery from low temperature exposure. We investigated the contribution of Fst expression to chill-coma recovery time, acute cold tolerance and rapid cold hardening (RCH) in adult D. melanogaster by knocking down Fst mRNA expression using GAL4/UAS-mediated RNA interference. In this experiment, four UAS-Fst and one tubulin-GAL4 lines were used. We predicted that if Fst is essential for cold tolerance phenotypes, flies with low Fst mRNA levels should be less cold tolerant than flies with normal levels of cold-induced Fst mRNA. Cold-induced Fst abundance and recovery time from chill-coma were not negatively correlated in male or female flies. Survival of 2 h exposures to sub-zero temperatures in Fst knockdown lines was not lower than that in a control line. Moreover, a low temperature pretreatment increased survival of severe cold exposure in flies regardless of Fst abundance level during recovery from cold stress, suggesting that Fst expression is not essential for RCH. Thus, cold-induced Fst accumulation is not essential for cold tolerance measured as chill-coma recovery time, survival to acute cold stress and RCH response in adult D. melanogaster.

Lesion Volume in Relapsing Multiple Sclerosis is Associated with Perivascular Space Enlargement at the Level of the Basal Ganglia.

BACKGROUND AND PURPOSE: Perivascular spaces surround the blood vessels of the brain and are involved in neuroimmune functions and clearance of metabolites via the glymphatic system of the brain. Enlarged perivascular spaces could be a marker of dysfunction in these processes and, therefore, are highly relevant to monitoring disease activity in MS. This study aimed to compare the number of enlarged perivascular spaces in people with relapsing MS with MR imaging markers of inflammation and brain atrophy. MATERIALS AND METHODS: Fifty-nine patients (18 with clinically isolated syndrome, 22 with early and 19 with late relapsing-remitting MS) were scanned longitudinally (mean follow-up duration = 19.6 [SD, 0.5] months) using T2-weighted, T1-weighted, and FLAIR MR imaging. Two expert raters identified and counted enlarged perivascular spaces on T2-weighted MR images from 3 ROIs (the centrum semiovale, basal ganglia, and midbrain). Baseline and change with time in the number of enlarged perivascular spaces were correlated with demographics and lesion and brain volumes. RESULTS: Late relapsing-remitting MS had a greater average number of enlarged perivascular spaces at baseline at the level of the basal ganglia (72.3) compared with early relapsing-remitting MS (60.5) and clinically isolated syndrome (54.7) (F = 3.4, P = .042), and this finding correlated with lesion volume (R = 0.44, P = .0004) but not brain atrophy (R = -0.16). Enlarged perivascular spaces increased in number with time in all regions, and the rate of increase did not differ among clinical groups. CONCLUSIONS: Enlarged perivascular spaces at the level of the basal ganglia are associated with greater neuroinflammatory burden, and the rate of enlargement appears constant in patients with relapsing-remitting disease phenotypes.

Basal cold but not heat tolerance constrains plasticity among Drosophila species (Diptera: Drosophilidae).

Thermal tolerance and its plasticity are important for understanding ectotherm responses to climate change. However, it is unclear whether plasticity is traded-off at the expense of basal thermal tolerance and whether plasticity is subject to phylogenetic constraints. Here, we investigated associations between basal thermal tolerance and acute plasticity thereof in laboratory-reared adult males of eighteen Drosophila species at low and high temperatures. We determined the high and low temperatures where 90% of flies are killed (ULT(90) and LLT(90) , respectively) and also the magnitude of plasticity of acute thermal pretreatments (i.e. rapid cold- and heat-hardening) using a standardized, species-specific approach for the induction of hardening responses. Regression analyses of survival variation were conducted in ordinary and phylogenetically informed approaches. Low-temperature pretreatments significantly improved LLT(90) in all species tested except for D. pseudoobscura, D. mojavensis and D. borealis. High-temperature pretreatment only significantly increased ULT(90) in D. melanogaster, D. simulans, D. pseudoobscura and D. persimilis. LLT(90) was negatively correlated with low-temperature plasticity even after phylogeny was accounted for. No correlations were found between ULT(90) and LLT(90) or between ULT(90) and rapid heat-hardening (RHH) in ordinary regression approaches. However, after phylogenetic adjustment, there was a positive correlation between ULT(90) and RHH. These results suggest a trade-off between basal low-temperature tolerance and acute low-temperature plasticity, but at high temperatures, increased basal tolerance was accompanied by increased plasticity. Furthermore, high- and low-temperature tolerances and their plasticity are clearly decoupled. These results are of broad significance to understanding how organisms respond to changes in habitat temperature and the degree to which they can adjust thermal sensitivity.

Metabolic rate and oxidative stress in insects exposed to low temperature thermal fluctuations.

Fluctuating temperatures are a predominant feature of the natural environment but their effects on ectotherm physiology are not well-understood. The warm periods of fluctuating thermal regimes (FTRs) provide opportunities for repair leading to increased survival, but there are also indications of negative effects of warm exposure. In this study, we examined respiration and oxidative stress in adult Alphitobius diaperinus exposed to FTRs and to constant low temperatures. We hypothesized that cold exposure will cause oxidative stress and that FTRs would reduce the amount of chill injuries, via activation of the antioxidant system. We measured V˙CO2, activities of super oxide dismutase (SOD), amounts of total (GSHt) and oxidized glutathione (GSSG) during cold and warm periods of FTRs. Increased severity of cold exposure caused a decrease in the glutathione pool. SOD levels increased during the recovery period in the more severe FTR. The antioxidant response was sufficient to counter the reactive oxygen species production, as the GSH:GSSG ratio increased. We conclude that cold stress causes oxidative damage in these beetles, and that a warm recovery period activates the antioxidant system allowing repair of cold-induced damage, leading to the increased survival previously noted in beetles exposed to fluctuating versus constant temperatures.

Giardia Colonizes and Encysts in High-Density Foci in the Murine Small Intestine.

Giardia lamblia is a highly prevalent yet understudied protistan parasite causing significant diarrheal disease worldwide. Hosts ingest Giardia cysts from contaminated sources. In the gastrointestinal tract, cysts excyst to become motile trophozoites, colonizing and attaching to the gut epithelium. Trophozoites later differentiate into infectious cysts that are excreted and contaminate the environment. Due to the limited accessibility of the gut, the temporospatial dynamics of giardiasis in the host are largely inferred from laboratory culture and thus may not mirror Giardia physiology in the host. Here, we have developed bioluminescent imaging (BLI) to directly interrogate and quantify the in vivo temporospatial dynamics of Giardia infection, thereby providing an improved murine model to evaluate anti-Giardia drugs. Using BLI, we determined that parasites primarily colonize the proximal small intestine nonuniformly in high-density foci. By imaging encystation-specific bioreporters, we show that encystation initiates shortly after inoculation and continues throughout the duration of infection. Encystation also initiates in high-density foci in the proximal small intestine, and high density contributes to the initiation of encystation in laboratory culture. We suggest that these high-density in vivo foci of colonizing and encysting Giardia likely result in localized disruption to the epithelium. This more accurate visualization of giardiasis redefines the dynamics of the in vivo Giardia life cycle, paving the way for future mechanistic studies of density-dependent parasitic processes in the host. IMPORTANCEGiardia is a single-celled parasite causing significant diarrheal disease in several hundred million people worldwide. Due to limited access to the site of infection in the gastrointestinal tract, our understanding of the dynamics of Giardia infections in the host has remained limited and largely inferred from laboratory culture. To better understand Giardia physiology and colonization in the host, we developed imaging methods to quantify Giardia expressing bioluminescent physiological reporters in two relevant animal models. We discovered that parasites primarily colonize and encyst in the proximal small intestine in discrete, high-density foci. We also show that high parasite density contributes to encystation initiation.

Mammary transcriptome analysis of lactating dairy cows following administration of bovine growth hormone.

The galactopoietic effect of growth hormone (GH) in lactating ruminants is well established; however the mechanisms that mediate these effects are not well understood. The first objective of this study was to determine the effect of GH on the synthesis of the major casein and whey proteins. The second objective was to identify the genes and pathways that may be involved in mediating the effect of GH on milk synthesis. A single subcutaneous injection of a commercially available slow release formulation of GH (Lactatropin®), or physiological saline solution (control) was administered to non-pregnant dairy cows (n=4/group) in mid-late lactation. Milk samples were collected for composition analysis and mammary lobulo-alveolar tissue was collected postmortem 6 days post injection. Gene expression profiles were evaluated using either a 22 000 bovine complementary DNA microarray or quantitative PCR (qPCR), and microarrays were validated by qPCR. The yield of all the major casein and whey proteins was increased 32% to 41% in GH-treated cows, with the exception of α-lactalbumin yield which was elevated by 70% relative to controls. Treatment with GH treatment tended to increase the concentration of α-lactalbumin but had no effect on the concentration of any of the major milk proteins. Messenger RNA (mRNA) abundance of the major whey and casein genes, with the exception of α-s2-casein, was increased in response to GH compared with controls, which is consistent with the positive effect of GH on milk production. Treatment with GH treatment influenced the mRNA abundance of genes involved in cell growth and proliferation, transcriptional and translational regulation, actin cytoskeleton signalling, lipid metabolism and cell death. This study has provided new insights into the cell signalling that may be involved in mediating the effect of GH on milk production in the mammary gland of lactating dairy cows.

Three-dimensional reconstruction of color Doppler flow convergence regions and regurgitant jets: an in vitro quantitative study.

OBJECTIVES: This study sought to investigate the applicability of a current implementation of a three-dimensional echocardiographic reconstruction method for color Doppler flow convergence and regurgitant jet imaging. BACKGROUND: Evaluation of regurgitant flow events, such as flow convergences or regurgitant jets, using two-dimensional imaging ultrasound color flow Doppler systems may not be robust enough to characterize these spatially complex events. METHODS: We studied two in vitro models using steady flow to optimize results. In the first constant-flow model, two different orifices were each mounted to produce flow convergences and free jets--a circular orifice and a rectangular orifice with orifice area of 0.24 cm(2). In another flow model, steady flows through a circular orifice were directed toward a curved surrounding wall to produce wall adherent jets. Video composite data of color Doppler flow images from both free jet and wall jet models were reconstructed and analyzed after computer-controlled 180 degrees rotational acquisition using a TomTec computer. RESULTS: For the free jet model there was an excellent relation between actual flow rates and three-dimensional regurgitant jet volumes for both circular and rectangular orifices (r = 0.99 and r = 0.98, respectively). However, the rectangular orifice produced larger jet volumes than the circular orifice, even at the same flow rates (p < 0.0001). Calculated flow rates by the hemispheric model using one axial measurement of the flow convergence isovelocity surface from two-dimensional color flow images underestimated actual flow rate by 35% for the circular orifice and by 44% for the rectangular orifice, whereas a hemielliptic method implemented using three axial measurements of the flow convergence zone derived using three-dimensional reconstruction correlated well with and underestimated actual flow rate to a lesser degree (22% for the circular orifice, 32% for the rectangular orifice). In the wall jet model, the jets were flattened against and spread along the wall and had reduced regurgitant jet volumes compared with free jets (p < 0.01). CONCLUSIONS: Three-dimensional reconstruction of flow imaged by color Doppler may add quantitative spatial information to aid computation methods that have been used for evaluating valvular regurgitation, especially where they related to complex geometric flow events.

Evaluation of aortic regurgitation with digitally determined color Doppler-imaged flow convergence acceleration: a quantitative study in sheep.

OBJECTIVES: The aim of the present study was to validate a digital color Doppler-based centerline velocity/distance acceleration profile method for evaluating the severity of aortic regurgitation. BACKGROUND: Clinical and in vivo experimental applications of the flow convergence axial centerline velocity/distance profile method have recently been used to estimate regurgitant flow rates and regurgitant volumes in the presence of mitral regurgitation. METHODS: In six sheep, a total of 19 hemodynamic states were obtained pharmacologically 14 weeks after the original operation in which a portion of the aortic noncoronary (n = 3) or right coronary (n = 3) leaflet was excised to produce aortic regurgitation. Echocardiographic studies were performed to obtain complete proximal axial flow acceleration velocity/distance profiles during the time of peak regurgitant flow (usually early in diastole) for each hemodynamic state. For each steady state, the severity of aortic regurgitation was assessed by measurement of the magnitude of the regurgitant flow volume/beat, regurgitant fraction and instantaneous regurgitant flow rates determined by using both aortic and pulmonary artery electromagnetic flow probes. RESULTS: Grade I regurgitation (regurgitant volume/beat < 15 ml, six conditions), grade II regurgitation (regurgitant volume/beat between 16 ml and 30 ml, five conditions) and grade III-IV regurgitation (regurgitant volume/beat > 30 ml, eight conditions) were clearly separated by using the color Doppler centerline velocity/distance profile domain technique. Additionally, an equation for correlating "a" (the coefficient from the multiplicative curve fit for the velocity/distance relation) with the peak regurgitant flow rates (Q [liters/min]) was derived showing a high correlation between calculated peak flow rates by the color Doppler method and the actual peak flow rates (Q = 13a + 1.0, r = 0.95, p < 0.0001, SEE = 0.76 liters/min). CONCLUSIONS: This study, using quantified aortic regurgitation, demonstrates that the flow convergence axial centerline velocity/distance acceleration profile method can be used to evaluate the severity of aortic regurgitation.

Acquired right ventricular outflow tract obstruction in the recipient twin in twin-twin transfusion syndrome.

OBJECTIVES: The goal of this study was to determine the prevalence and evolution of acquired right ventricular outflow tract obstruction (RVOTO) in the recipient twin in twin-twin transfusion syndrome (TTTS). BACKGROUND: Twin-twin transfusion syndrome complicates 4% to 26% of diamniotic monochorionic twin gestations and is associated with high fetal morbidity and mortality. Cardiac dysfunction and biventricular hypertrophy may develop in the recipient twin with the potential for RVOTO. METHODS: This was a retrospective review of a two-center experience of TTTS to describe the prevalence and evolution of acquired RVOTO in the recipient twin. Right ventricular outflow tract obstruction was diagnosed or excluded by fetal or postnatal echocardiography or clinical assessment. RESULTS: Of 73 twin pregnancies with TTTS identified between 1994 to 1998, a total of seven (9.6%) were complicated by RVOTO in the recipient twin: two subvalvar/muscular, four valvar and one combined. Of 44 pregnancies with fetal echo, six had in utero RVOTO with antegrade flow diagnosed at gestational ages ranging from 19 to 27 weeks. In utero progression occurred in four cases over a period of four to eight weeks, with the development of RVOT atresia by delivery. Postnatal progression of RVOTO occurred in two cases, one of which required pulmonary balloon valvuloplasty at age two years. Postnatal regression of subvalvar RVOTO occurred in two cases in early infancy. Death related directly or indirectly to the RVOTO occurred in all four patients who developed complete RVOT obliteration. CONCLUSIONS: Right ventricular outflow tract obstruction may occur in the recipient twin of at least 9% of pregnancies complicated by TTTS. Right ventricular outflow tract obstruction progression is common in utero and may worsen neonatal outcome.

Novel Methods of Measuring Hydraulic Conductivity of Tree Root Systems and Interpretation Using AMAIZED (A Maize-Root Dynamic Model for Water and Solute Transport).

Steady-state and dynamic methods were used to measure the conductivity to water flow in large woody root systems. The methods were destructive in that the root must be excised from the shoot but do not require removal of the root from the soil. The methods involve pushing water from the excised base of the root to the apex, causing flow in a direction opposite to that during normal transpiration. Sample data are given for two tropical (Cecropia obtusifolia and Lacistema aggregatum) and two temperate species (Acer saccharum and Juglans regia cv Lara). A hysteresis was observed in the relationship between applied pressure and resulting flow during dynamic measurements. A mathematical model (AMAIZED) was derived for the dynamics of solute and water flow in roots. The model was used to interpret results obtained from steady-state and dynamic measurements. AMAIZED is mathematically identical with the equations that describe Munch pressure flow of solute and water in the phloem of leaves. Results are discussed in terms of the predictions of AMAIZED, and suggestions for the improvement of methods are made.

Generalized cortical dysplasia manifested by diffusely thick cerebral cortex.

Unilateral or bilateral rolandic macrogyria has been described as a cause of epilepsy and, in some cases, retardation. Tissue from the periphery of these lesions shows the changes of focal cortical dysplasia. Evidence reported herein suggests that cortical dysplasia may also be generalized. Two patients with intractable epilepsy and mental retardation had diffusely abnormal, thick cortex, shallow gyri, and poor demarcation of gray and white matter. One patient had an anterior callosotomy that led to considerable improvement of the epilepsy. Cortical layers 5 and 6 could not be differentiated on biopsy material. The white matter was poorly myelinated and contained clusters of heterotopic neurons. This syndrome, a congenital disorder of neuronal migration, with prolonged survival, represents a mild form of lissencephaly. It can be diagnosed during life by computed tomography or magnetic resonance scanning.

Resection of the lesion in patients with hypothalamic hamartomas and catastrophic epilepsy.

BACKGROUND: Patients with hypothalamic hamartomas (HH) often have severe refractory epilepsy, incapacitating behavioral abnormalities, and cognitive decline. Attempts to control the seizure disorder by resection of apparently epileptogenic mesial temporal or other cortical structures have failed consistently. OBJECTIVE: To report a series of 13 patients in whom the hamartoma itself was resected. METHODS: All patients underwent preoperative evaluation between ages 2 and 33 years and had subtotal or complete resection of the hamartoma. Follow-up ranged from 1 to 5.5 years (mean: 2.8 y). RESULTS: Preoperatively, all patients had variable combinations of gelastic, complex partial, and generalized seizures. Eight had drop attacks. In addition, all had marked behavior abnormalities and cognitive impairment. Postoperatively, two patients are completely seizure-free and 11 are either seizure-free or have achieved a greater than 90% reduction of drop attacks and generalized tonic-clonic seizures. However, minor gelastic, complex partial, and atypical absence seizures have persisted in 11 patients, although at significantly reduced rates. In addition, there has been a dramatic improvement in behavior and cognition. Three patients had an anterior thalamic and one a capsular infarct, which left only minimal long-term deficits. Exact location of the lesion in relation to the interpeduncular fossa and the walls of the third ventricle correlated with extent of excision, seizure control, and complication rate. CONCLUSION: Resection can alleviate both the seizures and the behavioral and cognitive abnormalities of hypothalamic hamartomas, but complications are frequent.

Direct infusion of a variant of insulin-like growth factor-I into the skin of sheep and effects on local blood flow, amino acid utilization and cell replication.

In vivo effects of local infusion of a variant of insulin-like growth factor-I (IGF-I), long-R3-IGF-I, into the skin were investigated using six conscious sheep with food available ad libitum. An artery and vein on the abdominal flank of each animal, as well as the saphenous artery, were catheterized so that infusion of isotopically labelled amino acids, with or without IGF-I, could be used to determine amino acid uptake by arteriovenous difference in combination with blood flow determined by dye dilution. Measurements were made on each animal prior to IGF-I infusion, at hourly intervals for the 4 h of IGF-I infusion into the skin artery, then 2 and 4 h after IGF-I infusion ceased. Numbers of cells replicating in the bulbs of wool follicles in the IGF-I-infused area and in the skin on the contralateral side of each animal were measured after labelling with 5-bromo-2'-deoxyuridine. IGF-I caused a significant increase in the skin blood flow (P < 0.05), utilization of oxygen (P < 0.05), uptake of cysteine (P < 0.05) and phenylalanine (P < 0.001), and the rate of utilization of cysteine (P < 0.05) for protein synthesis. IGF-I increased amino acid uptake regardless of whether the skin was in negative or positive amino acid balance prior to infusion. During the recovery period amino acid utilization by skin returned towards preinfusion levels. No effects of IGF-I were found on replicating cell numbers in the bulbs of wool follicles.

Primary ciliary dyskinesia associated with a novel microtubule defect in a child with Down's syndrome.

We present a child with Down's syndrome, bilateral lower lobe bronchiectasis, sinusitis, and severe ear disease who was found to have a novel ciliary defect, with a frequent, partial absence of the walls of the A subunits of some peripheral doublets. The defect caused the A subunits to be "U-shaped" rather than "O-shaped." A nuclear nasal mucociliary transport study confirmed that this defect was associated with abnormal mucociliary transport. The ciliary defect was not observed in a biopsy performed in a second patient who had Down's syndrome.

Hemolytic anemia after atrioventricular septal defect repair without synthetic material.

We report a rare case of severe hemolytic anemia following repair of a congenital heart defect without the use of prosthetic material. A review of the literature, diagnosis, and management are described. Although this is an unusual complication following congenital heart surgery, a high index of suspicion must be maintained and a possible mechanical cause should be sought and corrected.

The pharmacology of hippocampal theta cells: evidence that the sensory processing correlate is cholinergic.

The firing repertoires of theta cells in the CA1 and dentate layers of the hippocampal formation of the freely moving rabbit were analyzed during 3 behavioral conditions: (1) voluntary motor patterns, termed type 1 theta behaviors; (2) automatic motor patterns, termed type 2LIA behaviors; (3) alert immobility with presentation of sensory stimuli, termed type 2 theta behavior. Cholinergic manipulations were shown to effect the firing repertoires of theta cells during the type 2 theta behavior condition (sensory processing) and not the other two behavioral conditions. A hypothesis of a sensorimotor processing function of the hippocampal formation is presented and discussed.