Plasmoid Formation and Strong Radiative Cooling in a Driven Magnetic Reconnection Experiment

We present the first experimental study of plasmoid formation in a magnetic reconnection layer undergoing rapid radiative cooling, a regime relevant to extreme astrophysical plasmas. Two exploding aluminum wire arrays, driven by the Z machine, generate a reconnection layer (S_{L}≈120) in which the cooling rate far exceeds the hydrodynamic transit rate (τ_{hydro}/τ_{cool}>100). The reconnection layer generates a transient burst of >1  keV x-ray emission, consistent with the formation and subsequent rapid cooling of the layer. Time-gated x-ray images show fast-moving (up to 50  km s^{-1}) hotspots in the layer, consistent with the presence of plasmoids in 3D resistive magnetohydrodynamic simulations. X-ray spectroscopy shows that these hotspots generate the majority of Al K-shell emission (around 1.6 keV) prior to the onset of cooling, and exhibit temperatures (170 eV) much greater than that of the plasma inflows and the rest of the reconnection layer, thus providing insight into the generation of high-energy radiation in radiatively cooled reconnection events.

High-resolution fiber imaging for pulsed power experiments

This work presents a novel approach for imaging the visible emissions from plasmas in pulsed power experiments using high-resolution plastic optical fibers. The diagnostic consists of a 2 mm diameter core commercial cable constructed of 13 000 individual acrylic fibers. The fibers are fused together to create a single high-resolution bundle. Different designs were investigated to cover a wide range of resolutions and fields of view (3-700 µm and 0.05-45 mm, respectively). The system was tested on the 1-MA Mykonos accelerator at Sandia National Laboratories and successfully imaged visible emission from a hybrid x-pinch target. Diagnostic development and preliminary results are presented.

A quarter of patients with type 1 diabetes have co-existing non-islet autoimmunity: the findings of a UK population-based family study

Individuals with type 1 diabetes (T1D) are at increased risk of coeliac disease (CD), autoimmune thyroiditis and autoimmune gastritis, but the absolute risks are unclear. The aim of this study was to investigate the prevalence of autoantibodies to tissue transglutaminase (TGA), thyroid peroxidase (TPOA) and gastric H⁺ /K⁺ -ATPase (ATPA) and their genetic associations in a well-characterized population-based cohort of individuals with T1D from the Bart's-Oxford family study for whom islet autoantibody prevalence data were already available. Autoantibodies in sera from 1072 patients (males/females 604/468; median age 11·8 years, median T1D duration 2·7 months) were measured by radioimmunoassays; HLA class II risk genotype was analysed in 973 (91%) using polymerase chain reaction with sequence specific primers (PCR-SSP). The prevalence of TGA (and/or history of CD), TPOA and ATPA in patients was 9·0, 9·6 and 8·2%, respectively; 3·1% had two or more autoantibodies. Females were at higher risk of multiple autoimmunity; TGA/CD were associated with younger age and TPOA with older age. ATPA were uncommon in patients under 5 years, and more common in older patients. Anti-glutamate decarboxylase autoantibodies were predictive of co-existing TPOA/ATPA. TGA/CD were associated with human leucocyte antigen (HLA) DR3-DQ2, with the DR3-DQ2/DR3-DQ2 genotype conferring the highest risk, followed by DR4-DQ8/DR4-DQ8. ATPA were associated with DR3-DQ2, DRB1*0404 (in males) and the DR3-DQ2/DR4-DQ8 genotype. TPOA were associated with the DR3-DQ2/DR3-DQ2 genotype. Almost one-quarter of patients diagnosed with T1D aged under 21 years have at least one other organ-specific autoantibody. HLA class II genetic profiling may be useful in identifying those at risk of multiple autoimmunity.

Delineating the phenotypic spectrum of Bainbridge-Ropers syndrome: 12 new patients with de novo, heterozygous, loss-of-function mutations in ASXL3 and review of published literature

BACKGROUND

Bainbridge-Ropers syndrome (BRPS) is a recently described developmental disorder caused by de novo truncating mutations in the additional sex combs like 3 (ASXL3) gene. To date, there have been fewer than 10 reported patients.

OBJECTIVES

Here, we delineate the BRPS phenotype further by describing a series of 12 previously unreported patients identified by the Deciphering Developmental Disorders study.

METHODS

Trio-based exome sequencing was performed on all 12 patients included in this study, which found a de novo truncating mutation in ASXL3. Detailed phenotypic information and patient images were collected and summarised as part of this study.

RESULTS

By obtaining genotype:phenotype data, we have been able to demonstrate a second mutation cluster region within ASXL3. This report expands the phenotype of older patients with BRPS; common emerging features include severe intellectual disability (11/12), poor/ absent speech (12/12), autistic traits (9/12), distinct face (arched eyebrows, prominent forehead, high-arched palate, hypertelorism and downslanting palpebral fissures), (9/12), hypotonia (11/12) and significant feeding difficulties (9/12) when young.

DISCUSSION

Similarities in the patients reported previously in comparison with this cohort included their distinctive craniofacial features, feeding problems, absent/limited speech and intellectual disability. Shared behavioural phenotypes include autistic traits, hand-flapping, rocking, aggressive behaviour and sleep disturbance.

CONCLUSIONS

This series expands the phenotypic spectrum of this severe disorder and highlights its surprisingly high frequency. With the advent of advanced genomic screening, we are likely to identify more variants in this gene presenting with a variable phenotype, which this study will explore.

Large-scale discovery of novel genetic causes of developmental disorders

Despite three decades of successful, predominantly phenotype-driven discovery of the genetic causes of monogenic disorders, up to half of children with severe developmental disorders of probable genetic origin remain without a genetic diagnosis. Particularly challenging are those disorders rare enough to have eluded recognition as a discrete clinical entity, those with highly variable clinical manifestations, and those that are difficult to distinguish from other, very similar, disorders. Here we demonstrate the power of using an unbiased genotype-driven approach to identify subsets of patients with similar disorders. By studying 1,133 children with severe, undiagnosed developmental disorders, and their parents, using a combination of exome sequencing and array-based detection of chromosomal rearrangements, we discovered 12 novel genes associated with developmental disorders. These newly implicated genes increase by 10% (from 28% to 31%) the proportion of children that could be diagnosed. Clustering of missense mutations in six of these newly implicated genes suggests that normal development is being perturbed by an activating or dominant-negative mechanism. Our findings demonstrate the value of adopting a comprehensive strategy, both genome-wide and nationwide, to elucidate the underlying causes of rare genetic disorders.

Maternal hepatitis B and hepatitis C infection and neonatal neurological outcomes

To examine the associations between maternal hepatitis B (HBV) and hepatitis C (HCV) infection status and selected infant neurological outcomes diagnosed at birth, we conducted a population-based, retrospective cohort study on singleton live births in Florida from 1998 to 2009. Primary exposures included maternal HBV and HCV monoinfection. The neurological outcomes included brachial plexus injury, cephalhematoma, foetal distress, feeding difficulties, intraventricular h aemorrhage and neonatal seizures. Multivariable logistic regression models were used to generate odds ratios (OR) and 95% confidence intervals (CI) that were adjusted for socio-demographic characteristics, risky behaviours, pregnancy complications and pre-existing medical conditions, and timing of delivery. The risk of an adverse neurological outcome was higher in infants born to mothers with hepatitis viral infection (7.2% for HCV, 5.0% for HBV), compared with infants of hepatitis virus-free mothers (4.2%). After adjusting for potential confounders, women with HBV were twice as likely to have infants who suffered from brachial plexus injury (OR = 2.04, 95% CI = 1.15-3.60), while those with HCV had an elevated odds of having an infant with feeding difficulties (OR: 1.32, 95% CI = 1.06-1.64) and a borderline increased likelihood for neonatal seizures (OR = 1.74, 95% CI = 0.98-3.10). Additionally, HCV+ mothers had a 22% increased odds of having an infant with some type of adverse neurological outcome (OR: 1.22, 95% CI = 1.03-1.44). Our findings add to current understanding of the association between maternal HBV/HCV infections and infant neurological outcomes. Further research evaluating the role of maternal HBV and HCV infections (including viraemia, treatment) on pregnancy outcomes is warranted.

Measuring stock and change in the GB countryside for policy--key findings and developments from the Countryside Survey 2007 field survey

Countryside Survey is a unique large scale long-term monitoring programme investigating stock and change of habitats, landscape features, vegetation, soil and freshwaters of Great Britain. Repeat field surveys combine policy and scientific objectives to provide evidence on how multiple aspects of the environment are changing over time, a key goal of international science in the face of profound human impacts on ecosystems. Countryside Survey 2007 (CS2007), the fifth survey since 1978, retained consistency with previous surveys, whilst evolving in line with technological and conceptual advances in the collection and integration of data to understand landscape change. This paper outlines approaches taken in the 2007 survey and its subsequent analysis and presents some of the headline results of the survey and their relevance for national and international policy objectives. Key changes between 1998 and 2007 included: a) significant shifts in agricultural land cover from arable to grassland, accompanied by increases in the area of broadleaved woodland, b) decreases in the length of managed hedges associated with agricultural land, as a proportion deteriorated to lines of trees and c) increases in the areas and numbers of wet habitats (standing open water, ponds) and species preferring wetter conditions (1998-2007 and 1978-2007). Despite international policy directed at maintaining and enhancing biodiversity, there were widespread decreases in species richness in all linear and area habitats, except on arable land, consistent with an increase in competitive and late successional species between 1998 and 2007 and 1978 and 2007. Late successional and competitive species: Stinging nettle (Urtica dioica), Hawthorn (Cratageous monogyna) and Bramble (Rubus fruticosus), in the top ten recorded species recorded in 2007, all increased between 1998 and 2007. The most commonly recorded species in CS (1990, 1998 and 2007) was agricultural Ryegrass (Lolium perenne). Increases in both water quality and soil pH were in line with policy aimed at addressing previous deterioration of both. Headwater streams broadly showed continued improvements in biological quality from 1998 to 2007, continuing trends seen since 1990. In soils, there were significant increases in soil pH between 1998 and 2007 consistent with recovery from acidification.

The association between Chiari-like malformation, ventriculomegaly and seizures in cavalier King Charles spaniels

Cavalier King Charles spaniels (CKCSs) with Chiari-like malformation (CM) and associated seizures are frequently diagnosed with idiopathic epilepsy. There could be an association between ventriculomegaly (V) or caudal fossa overcrowding (CCFP) and seizures. A retrospective case-control study was performed using MRI to investigate the possible association between these morphological abnormalities and seizures. Seizure semiology and, where possible, electroencephalographic (EEG) abnormalities were documented. Eighty-five CKCS with CM were included, 27 with seizures. There was no association between V or CCFP and seizures (P=0.10 and 0.71, respectively). Seizures were classified as having partial onset in 61% of individuals in the study population (95% CI 42.41-76.43%). Another cause of recurrent seizures in CKCS (such as familial epilepsy) is suspected, as previously reported.

Evaluation of brain tissue or cerebrospinal fluid with broadly reactive polymerase chain reaction for Ehrlichia, Anaplasma, spotted fever group Rickettsia, Bartonella, and Borrelia species in canine neurological diseases (109 cases)

BACKGROUND

Vector-transmitted microorganisms in the genera Ehrlichia, Anaplasma, Rickettsia, Bartonella, and Borrelia are commonly suspected in dogs with meningoencephalomyelitis (MEM), but the prevalence of these pathogens in brain tissue and cerebrospinal fluid (CSF) of dogs with MEM is unknown.

HYPOTHESIS/OBJECTIVES

To determine if DNA from these genera is present in brain tissue and CSF of dogs with MEM, including those with meningoencephalitis of unknown etiology (MUE) and histopathologically confirmed cases of granulomatous (GME) and necrotizing meningoencephalomyelitis (NME).

ANIMALS

Hundred and nine dogs examined for neurological signs at 3 university referral hospitals.

METHODS

Brain tissue and CSF were collected prospectively from dogs with neurological disease and evaluated by broadly reactive polymerase chain reaction (PCR) for Ehrlichia, Anaplasma, Spotted Fever Group Rickettsia, Bartonella, and Borrelia species. Medical records were evaluated retrospectively to identify MEM and control cases.

RESULTS

Seventy-five cases of MUE, GME, or NME, including brain tissue from 31 and CSF from 44 cases, were evaluated. Brain tissue from 4 cases and inflammatory CSF from 30 cases with infectious, neoplastic, compressive, vascular, or malformative disease were evaluated as controls. Pathogen nucleic acids were detected in 1 of 109 cases evaluated. Specifically, Bartonella vinsonii subsp. berkhoffii DNA was amplified from 1/6 dogs with histopathologically confirmed GME.

CONCLUSION AND CLINICAL IMPORTANCE

The results of this investigation suggest that microorganisms in the genera Ehrlichia, Anaplasma, Rickettsia, and Borrelia are unlikely to be directly associated with canine MEM in the geographic regions evaluated. The role of Bartonella in the pathogenesis of GME warrants further investigation.

Does choice of imaging modality affect outcome in dogs with thoracolumbar spinal conditions?

OBJECTIVES

A retrospective cross-sectional study was done to look for differences in outcome in canine spinal patients that had myelography compared to those that had magnetic resonance imaging.

METHODS

Medical records of dogs with spinal conditions in the period January 2004 to December 2007 were reviewed. Data on patient age, gender, breed, size, neurolocalisation, rate of onset, imaging modality, time taken to image, type of treatment, neurological grade at admission and discharge, length and cost of hospitalisation and status at discharge were collected. Only dogs with neurological grade 3 to 6 with signs referable to the thoracolumbar spine were included.

RESULTS

Of 107 dogs that met the inclusion criteria, 66 (62%) had myelography and 41 (38%) had magnetic resonance imaging. Using multivariable analyses, non-chondrodystrophoid breed, increasing age and higher neurological grade at admission were found to be associated negatively with survival. Neurological grade 5 at admission was found to be associated positively with likelihood of neurological improvement. Male gender, higher neurological grade at admission and medical treatment were associated negatively with length of hospitalisation. magnetic resonance imaging, surgical treatment and period of hospitalisation were associated positively with total cost of hospitalisation.

CLINICAL SIGNIFICANCE

No significant association was found between type of imaging and any patient outcome variables except cost of hospitalisation, which was higher for dogs having magnetic resonance imaging. Although magnetic resonance imaging may be considered advantageous compared to myelography because it is non-invasive and provides superior anatomical detail for surgical guidance, no beneficial effect on outcome of dogs with non-ambulatory thoracolumbar spinal disease was found.

Multi-focal cerebral oligoastrocytoma in a puppy

A nine-month-old puppy was presented for investigation of seizures. Neurological deficits were found localising to the prosencephalon, mesencephalon and myelencephalon. Magnetic resonance imaging identified multiple, large lesions involving both cerebral hemispheres. Management with antiepileptic and immunomodulatory drugs was instituted; however, the seizures became progressively refractory and the puppy was euthanased. Histopathology following post-mortem examination found a mixed glial cell tumour with discrete areas where neoplastic cells appeared oligodendroglial or astrocytic. Primary intracranial neoplasia is a rare cause of neurological disease in young dogs. Moreover, this case is unusual in terms of both the mixed glial nature of the neoplasm and also its multi-focal distribution.

Multiple mechanisms are implicated in the generation of 5q35 microdeletions in Sotos syndrome

BACKGROUND

Sotos syndrome is characterised by learning difficulties, overgrowth, and a typical facial appearance. Microdeletions at 5q35.3, encompassing NSD1, are responsible for approximately 10% of non-Japanese cases of Sotos. In contrast, a recurrent approximately 2 Mb microdeletion has been reported as responsible for approximately 50% of Japanese cases of Sotos.

METHODS

We screened 471 cases for NSD1 mutations and deletions and identified 23 with 5q35 microdeletions. We investigated the deletion size, parent of origin, and mechanism of generation in these and a further 10 cases identified from published reports. We used "in silico" analyses to investigate whether repetitive elements that could generate microdeletions flank NSD1.

RESULTS

Three repetitive elements flanking NSD1, designated REPcen, REPmid, and REPtel, were identified. Up to 18 cases may have the same sized deletion, but at least eight unique deletion sizes were identified, ranging from 0.4 to 5 Mb. In most instances, the microdeletion arose through interchromosomal rearrangements of the paternally inherited chromosome.

CONCLUSIONS

Frequency, size, and mechanism of generation of 5q35 microdeletions differ between Japanese and non-Japanese cases of Sotos. Our microdeletions were identified from a large case series with a broad range of phenotypes, suggesting that sample selection variability is unlikely as a sole explanation for these differences and that variation in genomic architecture might be a contributory factor. Non-allelic homologous recombination between REPcen and REPtel may have generated up to 18 microdeletion cases in our series. However, at least 15 cannot be mediated by these repeats, including at least seven deletions of different sizes, implicating multiple mechanisms in the generation of 5q35 microdeletions.

Brain and spinal cord haemorrhages associated with Angiostrongylus vasorum infection in four dogs

Multifocal haemorrhages associated with Angiostrongylus vasorum infection were observed in the central nervous system of four dogs with neurological signs including depression, seizures, spinal pain and paresis. In magnetic resonance images the majority of the lesions were isointense or slightly hyperintense in T1-weighted images, hyperintense in T2-weighted images and hypointense in T2*-weighted (gradient echo) images, compatible with haemorrhages more than seven days old. Lesions were found in the brain of three of the dogs and in the spinal cord of two. The cerebrospinal fluid contained high concentrations of protein and evidence of erythrophagia. All the dogs had coagulopathy and pulmonary haemorrhage of varying severity. A vasorum larvae were detected in the faeces of each of the dogs. Neural A vasorum was confirmed at postmortem examination in two dogs.

Apoptosis in human cultured trophoblasts is enhanced by hypoxia and diminished by epidermal growth factor

Preeclampsia and fetal growth restriction are associated with placental hypoperfusion and villous hypoxia. The villous response to this environment includes diminished trophoblast differentiation and enhanced apoptosis. We tested the hypothesis that hypoxia induces apoptosis in cultured trophoblasts, and that epidermal growth factor (EGF), an enhancer of trophoblast differentiation, diminishes hypoxia-induced apoptosis. Trophoblasts isolated from placentas of term-uncomplicated human pregnancies were cultured up to 72 h in standard (PO(2) = 120 mm Hg) or hypoxic (PO(2) <15 mm Hg) conditions. Exposure to hypoxia for 24 h markedly enhanced trophoblast apoptosis as determined by DNA laddering, internucleosomal in situ DNA fragmentation, and histomorphology, as well as by the reversibility of the apoptotic process with a caspase inhibitor. Apoptosis was accompanied by increased expression of p53 and Bax and decreased expression of Bcl-2. Addition of EGF to cultured trophoblasts or exposure of more differentiated trophoblasts to hypoxia significantly lowered the level of apoptosis. We conclude that hypoxia enhances apoptosis in cultured trophoblasts by a mechanism that involves an increase in p53 and Bax expression. EGF and enhancement of cell differentiation protect against hypoxic-induced apoptosis.

Syringohydromyelia in Cavalier King Charles spaniels

Syringohydromyelia secondary to foramen magnum overcrowding is described in seven Cavalier King Charles spaniels. Clinical signs were consistent with a central spinal cord lesion. The most common signs were persistent scratching at the shoulder region with apparent neck, thoracic limb, or ear pain and thoracic limb lower motor neuron deficits. The diagnosis was made by magnetic resonance imaging. The syringohydromyelia is postulated to be a consequence of an occipital bone malformation resulting in a small caudal fossa and cerebellar herniation. Clinical signs improved but did not completely resolve when the dogs received treatment with corticosteroids or nonsteroidal anti-inflammatory drugs.

Registrar experience in vaginal breech delivery. How much is occurring?

The debate surrounding the safety of vaginal breech delivery compared to Caesarean delivery may be close to resolution, with a large randomized trial underway. However, trends in the management of vaginal breech delivery over recent years have led to suggestions that training in the technique of such deliveries may be inadequate. We have attempted to quantify the level of training in vaginal breech delivery available to registrars. This was accomplished by surveying obstetric training schemes in comparable regions of England and South Australia. Our findings suggest that registrar exposure to this important obstetric skill may be insufficient to guarantee expertise.

Melanocanthoma: a rare cause of oral hyperpigmentation

The oral features of a black woman with melanocanthoma of the oral mucosa are detailed, and the current literature of melanocanthoma of the oral mucosa is briefly reviewed.

Partial trisomy 15q: report of a patient and literature review

We report a girl with severe developmental delay, scoliosis and mild dysmorphism. She was found to have a partial duplication of the long arm of chromosome 15. Precise cytogenetic diagnosis was possible after additional in situ hybridisation. A Karyotype of 46,XX,dup (15) (pter-->q26.3::q24-->qter) was concluded. We compare her data with the literature. No specific phenotype was found.

Development of squamous cell carcinoma in hepatitis C virus-associated lichen planus

The hepatitis C virus may occasionally be associated with oral lichen planus. The present report details the features of a patient with hepatitis C virus infection and oral lichen planus who developed a squamous cell carcinoma of the tongue.

Computer assisted learning (CAL) of oral manifestations of HIV disease

General dental practitioners (GDPs) in the UK may wish additional education on relevant aspects of human immunodeficiency virus (HIV) disease. The aim of the present study was to develop and assess a computer assisted learning package on the oral manifestations of HIV disease of relevance to GDPs. A package was developed using a commercially-available software development tool and assessed by a group of 75 GDPs interested in education and computers. Fifty-four (72%) of the GDPs completed a self-administered questionnaire of their opinions of the package. The majority reported the package to be easy to load and run, that it provided clear instructions and displays, and that it was a more effective educational tool than videotapes, audiotapes, professional journals and textbooks, and of similar benefit as post-graduate courses. The GDPs often commented favourably on the effectiveness of the clinical images and use of questions and answers, although some had criticisms of these and other aspects of the package. As a consequence of this investigation the package has been modified and distributed to GDPs in England and Wales.

Detachment of transformed cells. Role of CD44 variants

A parallel-plate flow chamber was used to quantify the detachment of normal cloned rat embryo fibroblasts (CREF) fibroblasts, ras-transformed CREF fibroblasts (CREF T24), and CREF T24 fibroblasts transfected with a Krev/RAP1A suppressor gene (HK B1) from a confluent monolayer of normal CREF fibroblasts to determine if the expression patterns of CD44 variants (mol wt 110 and 140 kDa) corresponded with detachment properties and metastatic potential. In the detachment assay, known shear stresses ranging from 20-24 dyn/cm2 were applied to the adherent cells and the number of cells detached from the monolayer after 180 s was determined. Results showed that cellular expression of CD44 variants correlated with the metastatic potential of the cells and with the cells' ability to detach from a monolayer of normal cells. Western blot analysis showed a low level of expression of the CD44 variants in the normal cell line, CREF, and the lowly metastatic cell line, HK B1. Detachment studies showed a low percentage of detachment of both of these cell lines from a normal cell monolayer. Tumor-derived (HK B1-T) and lung nodule-derived (HK B1-M) cell lines were established and both formed tumors and metastasis with reduced latency periods as compared to HK B1, but still showed a markedly delayed latency period compared to the highly metastatic cell line, CREF T24. Both of these cell lines showed a higher expression of the CD44 variants as compared to CREF and HK B1, and detached easier than CREF and HK B1. CREF T24 showed a much higher level of expression of the variants and had a higher percentage detachment than all other cell lines. To further test the role of the CD44 variants in the ability of the cells to detach from the normal monolayer, CREF cells were transfected with a DNA construct that constitutively expresses the CD44 variants and the detachment properties of three randomly selected clones were studied. Clones 2 and 3 showed a low level of expression of the CD44 variants after transfection and detached from the normal monolayer similar to CREF. Clone 1 showed a high level of expression of the CD44 variants and the detachment of these cells was significantly higher than CREF. From these results, it is concluded that in the five cell lines studied, expression of the CD44 variants play a significant role in the ability of the cells to detach from a monolayer of normal cells. It is hypothesized that this detachment may be an important component of a cell's ability to metastasize.

The immune response of sheep infected with larvae of the sheep blowfly Lucilia cuprina monitored via efferent lymph

Changes in lymphocyte traffic in efferent lymph from the prescapular lymph node of sheep were monitored during local primary and secondary infection with blowfly, Lucilia cuprina. During primary infections the response was characterised by an increase in the output of CD4+ T cells over CD8+ T cells for the first 48 h after wound initiation. By 72 h the output of CD8+ T cells exceeded that of CD4+ T cells. During secondary infections the increased output of CD8+ T cells was more pronounced and occurred earlier at approximately 48 h. The percentage of B lymphocytes as measured by sIg, CD45R and MHC class II expression increased at approximately 96-120 h after both primary and secondary infections, with the secondary response being greater than the primary. This increase in B cells corresponded with peak antibody titres recorded in the efferent lymph to a first instar antigen preparation as measured by ELISA. An increase in IFN-gamma and soluble IL-2 receptor was recorded after both primary and secondary infections, with the response after secondary infection being greater than that recorded after primary larval infections.

Isolation of a human biliary glycoprotein inhibitor of cholesterol crystallization

BACKGROUND

About 50% of populations in developed countries have bile supersaturated with cholesterol, which is a major risk factor for cholesterol gallstone formation. Despite the prevalence of supersaturated bile, only about 10% of these populations develop gallstones. The existence of a biliary protein that inhibits cholesterol crystallization was hypothesized to explain this discrepancy. This report outlines the purification and characterization of such a human biliary glycoprotein.

METHODS

Chromatographic methods were used for separation and characterization. Additional steps included activity analysis by crystal growth assay, electrophoresis, and deglycosylation.

RESULTS

The glycoprotein consists of a heterodimer, M(r) of 120 kilodalton, with subunits of M(r) of 63 kilodalton and 58 kilodalton. Each of the subunits is characterized by an isoelectric point of 6.6 and shows comparable inhibitory activity. Deglycosylation of the subunits show that they share a similar polypeptide backbone (M(r) of 35 kilodalton) based upon a highly similar amino acid profile. This suggests that differential subunit glycosylation alone may account for the apparent heterodimeric structure.

CONCLUSIONS

No other human biliary glycoprotein has been found thus far that shows cholesterol crystal growth-inhibiting activity. Thus, it may be of importance in preventing gallstone formation in healthy populations.

A novel transcellular transport pathway for non-bile salt cholephilic organic anions

Non-bile salt cholephilic organic anions comprise a single class of nonhomologous ligands having a range of hydrophobicity. Hydrophobicity enhances the hepatic extraction of cholephiles as well as their partitioning into secreted biliary lipid particles. When hydrophobicity is correlated with patterns of biliary excretion for studying transcellular transport, however, the more hydrophobic probes are unsuitable. Specifically, with the isolated perfused rat liver technique, the excretory times for sulfobromophthalein and rose bengal were significantly longer compared with that for the much more hydrophilic analogue phenol red (PR), which showed only a single, nearly symmetrical excretory peak at 10 min. Colchicine affected the apparently well-defined PR pathway only at a saturation dose (10,000 times the tracer dose). In contrast, the effect of a different perturbant, monensin, was striking at a tracer dose of PR, but was less evident at a saturation dose. The combined administration of colchicine and monensin had no additive inhibitory effect on PR excretion at tracer doses. At a saturation dose of PR, where monensin is less inhibiting, however, a significant additive inhibitory effect was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Transcellular transport of organic anions in the isolated perfused rat liver: the differential effects of monensin and colchicine

Nonbile salt cholephiles and bile salts are two classes of organic anions that are efficiently taken up and excreted by the liver. Recent evidence suggests that a microtubular system-dependent, colchicine-sensitive transcellular pathway may transport both classes of these ligands. The relationship of this pathway to flux rates, however, remains unclear. Some structural evidence suggests an important role for a Golgi-associated vesicular system. Monensin, like colchicine, is a perturbing agent that is believed to target primarily Golgi and related organelles. The effects of a minimal effective dose of both colchicine (0.06 mg to 0.12 mg/100 gm body wt) and monensin (0.6 mg/100 gm body wt) were examined in the isolated perfused rat liver in a single-pass mode. The nonbile salt cholephile, phenol red, was studied at two doses: 1 nmol and 5 mumol. Sodium taurocholate was studied at three doses: 2 nmol, 1 mumol and 5 mumol. Colchicine affected the transcellular transport for both classes of organic anions equally. Partially inhibitory effects on both anions occurred only at high ligand flux rates. In contrast, monensin greatly impaired the transport of nonbile salt cholephiles but had no influence on transcellular bile salt flux. We conclude that the monensin effect appears to define a distinct transcellular transport pathway for each of the two classes of organic anions.

The perceptual priming phenomenon in amnesia

Alcoholic Korsakoff patients and controls were given three variants of a priming task. In the first task, a study list of words was followed by a recognition test phase and then a perceptual identification test phase. In the second task, the order of the two test phases was reversed. The amnesics performed like normals on the priming for identification task and the delay did not affect their performance. However, recognition by amnesics was significantly impaired when the delay was introduced; although it too was normal with no delay. In a third task, pseudowords were used as stimuli. Under these conditions the amnesics could not be primed nor could they recognize the material. The implications of these findings for current theories of amnesia were discussed.