Nuclear export of circular RNA

Circular RNAs (circRNAs), which are increasingly being implicated in a variety of functions in normal and cancerous cells1-5, are formed by back-splicing of precursor mRNAs in the nucleus6-10. circRNAs are predominantly localized in the cytoplasm, indicating that they must be exported from the nucleus. Here we identify a pathway that is specific for the nuclear export of circular RNA. This pathway requires Ran-GTP, exportin-2 and IGF2BP1. Enhancing the nuclear Ran-GTP gradient by depletion or chemical inhibition of the major protein exporter CRM1 selectively increases the nuclear export of circRNAs, while reducing the nuclear Ran-GTP gradient selectively blocks circRNA export. Depletion or knockout of exportin-2 specifically inhibits nuclear export of circRNA. Analysis of nuclear circRNA-binding proteins reveals that interaction between IGF2BP1 and circRNA is enhanced by Ran-GTP. The formation of circRNA export complexes in the nucleus is promoted by Ran-GTP through its interactions with exportin-2, circRNA and IGF2BP1. Our findings demonstrate that adaptors such as IGF2BP1 that bind directly to circular RNAs recruit Ran-GTP and exportin-2 to export circRNAs in a mechanism that is analogous to protein export, rather than mRNA export.

Mechanism of Bloom syndrome complex assembly required for double Holliday junction dissolution and genome stability

The RecQ-like helicase BLM cooperates with topoisomerase IIIα, RMI1, and RMI2 in a heterotetrameric complex (the "Bloom syndrome complex") for dissolution of double Holliday junctions, key intermediates in homologous recombination. Mutations in any component of the Bloom syndrome complex can cause genome instability and a highly cancer-prone disorder called Bloom syndrome. Some heterozygous carriers are also predisposed to breast cancer. To understand how the activities of BLM helicase and topoisomerase IIIα are coupled, we purified the active four-subunit complex. Chemical cross-linking and mass spectrometry revealed a unique architecture that links the helicase and topoisomerase domains. Using biochemical experiments, we demonstrated dimerization mediated by the N terminus of BLM with a 2:2:2:2 stoichiometry within the Bloom syndrome complex. We identified mutations that independently abrogate dimerization or association of BLM with RMI1, and we show that both are dysfunctional for dissolution using in vitro assays and cause genome instability and synthetic lethal interactions with GEN1/MUS81 in cells. Truncated BLM can also inhibit the activity of full-length BLM in mixed dimers, suggesting a putative mechanism of dominant-negative action in carriers of BLM truncation alleles. Our results identify critical molecular determinants of Bloom syndrome complex assembly required for double Holliday junction dissolution and maintenance of genome stability.

Parathyroid Hormone Related Peptide Elevations in Normocalcemic Adults

Introduction/Objective

Elevated parathyroid hormone-related peptide (PTHrP) is a biomarker often associated with hypercalcemia of malignancy. However, elevations of PTHrP can be seen in non-malignant patients with normal calcium status, notably renal failure. We investigate whether a LC-MS/MS test that specifically measures a peptide in the middle region of PTHrP fragments is immune to false elevations of PTHrP. Furthermore, we examine if PTHrP/PTH ratio or renal status can be used to further characterize PTHrP elevations in a cohort of normocalcemic patients.

Methods/Case Report

We conducted a retrospective study on adult patients that had at least one PTHrP laboratory test (i.e., ARUP PTHrP by LC-MS/MS) within the past 10 years (01/01/2011 to 04/29/2021) at a large academic center. We further stratified this cohort by demographics and additional laboratory markers including calcium status, parathyroid hormone (PTH) (i.e., by Siemens Centaur assay (Malvern, PA)), renal status, and known malignancies.

Results (if a Case Study enter NA)

We identified a total of 941 patients (585 female and 356 male). 33% of patients (30% [70/233] female and 36% [84/236] male) with elevated PTHrP were normocalcemic (i.e., did not have an elevation in calcium, ionized calcium, or diagnosis of hypercalcemia). 95% (21/22) of normocalcemic males and 100% (17/17) of normocalcemic females with an elevated PTHrP and elevated PTH had a PTHrP/PTH ratio below the normal sex specific reference ranges of 1.07 and 1.86, respectively. A subset of normocalcemic patients with elevated PTHrP had an estimated glomerular filtration rate (eGFR) recorded. Of these patients, 100% (58/58) of females and 94% (65/59) of males had an eGFR below 90 mL/min/1.73 m2 had an eGFR less than 30 mL/min/1.73 m2. and 50% (29/58) of females and 38% (26/69) of males

Conclusion

Our study supports the hypothesis that elevated PTHrP in the setting of normal calcium may occur due to renal insufficiency.

Domain-general and domain-specific influences on emerging numerical cognition: Contrasting uni-and bidirectional prediction models

Domain-general skills such as executive functions (EFs), and domain-specific skills such as non-symbolic number sense and symbolic understanding are often pitted against each other as predictors of emerging maths. Here we aimed to investigate early childhood relations between these foundational skills with a balanced, longitudinal design. One hundred and seventy 3- and 4-year-old-children were tested at two time points, 5 months apart, on four domain-general executive and five domain-specific numeracy tasks. A latent EF factor was a strong predictor of symbolic maths and of their growth. In addition, stronger symbolic maths at Time 1 was correlated with later stronger EF, but symbolic maths did not predict EF growth. Our findings provide novel insights into dynamic interplay between general and specific cognitive skills contributing to preschool maths.

Association of clinical severity with FANCB variant type in Fanconi anemia

Fanconi anemia (FA) is the most common genetic cause of bone marrow failure and is caused by inherited pathogenic variants in any of 22 genes. Of these, only FANCB is X-linked. We describe a cohort of 19 children with FANCB variants, from 16 families of the International Fanconi Anemia Registry. Those with FANCB deletion or truncation demonstrate earlier-than-average onset of bone marrow failure and more severe congenital abnormalities compared with a large series of FA individuals in published reports. This reflects the indispensable role of FANCB protein in the enzymatic activation of FANCD2 monoubiquitination, an essential step in the repair of DNA interstrand crosslinks. For FANCB missense variants, more variable severity is associated with the extent of residual FANCD2 monoubiquitination activity. We used transcript analysis, genetic complementation, and biochemical reconstitution of FANCD2 monoubiquitination to determine the pathogenicity of each variant. Aberrant splicing and transcript destabilization were associated with 2 missense variants. Individuals carrying missense variants with drastically reduced FANCD2 monoubiquitination in biochemical and/or cell-based assays tended to show earlier onset of hematologic disease and shorter survival. Conversely, variants with near-normal FANCD2 monoubiquitination were associated with more favorable outcome. Our study reveals a genotype-phenotype correlation within the FA-B complementation group of FA, where severity is associated with level of residual FANCD2 monoubiquitination.

Verocytotoxin Escherichia coli-Associated Haemolytic Uraemic Syndrome

Aims To describe laboratory data on clinical human Verotoxigenic E. coli (VTEC) strains causing haemolytic uraemic syndrome (HUS) and to characterise the VTEC strains, thus contributing to risk mitigation to decrease HUS incidence in Ireland. Methods Laboratory characterisation was performed on isolates from 52 VTEC-associated HUS cases identified in the National clinical VTEC Reference Laboratory (NRL-VTEC) for the years 2012-2014. Data were analysed with respect to age, gender, serogroup and verotoxin type and subtype. Results 52/83 (62.6%) culture positive HUS cases were identified from laboratory data; 30 (57.7%) cases occurred in females. Seven HUS-associated serogroups and eleven patterns of verotoxin subtypes are described. Conclusion Ireland has the highest incidence of VTEC infection in Europe and a variety of VTEC serogroups causing clinical infection, suggesting any viable VTEC may potentially cause HUS. A broad diagnostic approach, to detect uncommon serotypes, should be considered when analysing clinical and food samples for VTEC.

ATP-dependent helicase activity is dispensable for the physiological functions of Recql4

Rothmund-Thomson syndrome (RTS) is a rare autosomal recessive disorder characterized by skin rash (poikiloderma), skeletal dysplasia, small stature, juvenile cataracts, sparse or absent hair, and predisposition to specific malignancies such as osteosarcoma and hematological neoplasms. RTS is caused by germ-line mutations in RECQL4, a RecQ helicase family member. In vitro studies have identified functions for the ATP-dependent helicase of RECQL4. However, its specific role in vivo remains unclear. To determine the physiological requirement and the biological functions of Recql4 helicase activity, we generated mice with an ATP-binding-deficient knock-in mutation (Recql4^K525A). Recql4^K525A/K525A mice were strikingly normal in terms of embryonic development, body weight, hematopoiesis, B and T cell development, and physiological DNA damage repair. However, mice bearing two distinct truncating mutations Recql4^G522Efs and Recql4^R347*, that abolished not only the helicase but also the C-terminal domain, developed a profound bone marrow failure and decrease in survival similar to a Recql4 null allele. These results demonstrate that the ATP-dependent helicase activity of Recql4 is not essential for its physiological functions and that other domains might contribute to this phenotype. Future studies need to be performed to elucidate the complex interactions of RECQL4 domains and its contribution to the development of RTS.

DNA helicases unwind double-stranded nucleic acids using energy from ATP to access genetic information during cell replication. In humans, several families of helicases have been described and one of particular importance is the RecQ family, where mutations in three of five members cause human disease. RECQL4 is a member of this family and its mutation results in Rothmund-Thomson syndrome (RTS). Prior studies have shown that defects in the helicase region of RECQL4 may contribute to the disease, but no studies have specifically assessed the biological effects of its absence in a whole animal model. In this study, we generated a mouse model with a specific point mutation resulting in a helicase-inactive Recql4 protein. We found that an absence of ATP-dependent helicase activity does not perturb the physiological functions of Recql4 with the homozygous mutants being normal. In contrast, when we assessed point mutations that generate protein truncations these were pathogenic. Our results suggest that the helicase function of Recql4 is not essential for its physiological functions and that other domains of this protein might account for its functions in diseases such as RTS.

Epilepsy in Irish psychiatric inpatient settings

Aims To ascertain epilepsy prevalence in Irish psychiatric inpatient units and compliance with care planning guidelines. Methods Case records were reviewed in seven psychiatric inpatient units. Results The prevalence of epilepsy across seven psychiatric inpatient units (n=9/267) was three times that of general population estimates. Minimal data was recorded pertaining to seizure type (n=1,11.1%), triggers (n=2,22.2%), clinical investigations relating to epilepsy (n=2,22%) and no epilepsy risk assessments were recorded (n=0,0%). Conclusions The introduction of appropriate care plans is needed to optimise physical and mental wellbeing of those with epilepsy in psychiatric units.

Flavonoid rich dark cocoa may improve fatigue in people with multiple sclerosis, yet has no effect on glycaemic response: An exploratory trial

CONTEXT

Current research suggests that dark cocoa may reduce fatigue; however, the effect on fatigue in people with MS (pwMS) has never been established. The objective of this feasibility study was to explore the acute effect of high flavonoid cocoa on measures of fatigue and glycaemic response.

METHODS

This was a randomised crossover participant blind exploratory study in 12 participants (2 male and 10 female) with MS-related fatigue (>4 on the Fatigue Severity Scale; FSS). After fasting overnight, participants consumed the high flavonoid cocoa drink (350 mg gallic acid equivalents {GAE}/g) or a low flavonoid cocoa control (120 mg GAE/g), consuming the alternative drink on the next visit. Fatigue was self-reported on a 100 mm visual analogue scale at 30-min time intervals for 2 h post cocoa consumption and every 2 h for the rest of the day. Fatigability was monitored using a 6 min walk test (6MWT) at the end of the visit (2 h), and activity monitors worn for 24 h commencing at 12 noon on the day of testing. The feasibility of performing the trial including outcome measures was documented.

RESULTS

A moderate effect was found in self-reported fatigue throughout the day in favour of the high flavonoid group (Cohen's d 0.32, 95% non-central t CI -0.57 to 1.20). Fatigability measures did not change. Participants consumed and enjoyed the cocoa, all participants completed the study and outcome measures were accepted.

CONCLUSION

The results of this study support further trials to investigate the feasibility and efficacy of pure cocoa as a dietary supplement for fatigue in pwMS.

Abstract OT3-04-03: The impact of the 21 gene recurrence score (RS) on chemotherapy prescribing in estrogen receptor (ER) positive, lymph node positive early stage breast cancer in Ireland

BACKGROUND

For Estrogen Receptor (ER) positive, early stage breast cancer, the 21 gene Recurrence Score (RS) has clinical use both as a prognostic tool and to predict chemotherapy benefit. The availability of this tool in Ireland has led to a reduction in the use of adjuvant chemotherapy for women with lymph node (LN) negative disease. However, the RS is not routinely funded for patients with LN positive (LN+) breast cancer in Ireland. In addition, there are limited international data on the use of this tool in the preoperative setting. In this prospective observational study, we are investigating whether access to the 21 gene RS leads to a reduction in the receipt of chemotherapy for patients with ER+, LN+ breast cancer, and to correlate the 21 gene RS with response to preoperative systemic therapy.

TRIAL DESIGN

This is a national, multi-site, prospective, observational study that will examine the impact of the 21 gene RS on chemotherapy recommendations in both the neoadjuvant and adjuvant setting. Prior to and following tumor testing with the 21 gene RS, Physicians will complete a questionnaire which details type and strength of systemic therapy recommendations.

ELIGIBILITY

Cohort 1 (postoperative) will include patients with ER+ tumors of any size with involvement of 1-3 lymph nodes (N1 including micrometastases). Cohort 2 (preoperative) will include patients with ER+, T2-T4 tumors with biopsy proven nodal metastases. Both cohorts will have ECOG PS 0 or 1 and be fit for consideration of chemotherapy as determined by the Investigator.

SPECIFIC AIMS

The primary endpoint is the percentage reduction in the number of patients for whom treating physicians recommend chemotherapy after testing with 21 gene RS. Secondary endpoints include the correlation between the 21 gene RS and residual cancer burden score, as well as pathological, clinical and radiological response rates. The economic impact of the 21 gene RS in ER+, LN+ will also be assessed.

STATISTICAL METHODS

The sample size is based on similar decision impact studies conducted in other countries. Physician recommendations for chemotherapy pre 21-gene RS and recommendations post 21-gene RS testing will be compared and percentage change estimated with 95% confidence intervals. For secondary endpoints, the Pearson correlation coefficient (rho) will be used to examine the strength of the correlation between the 21 gene RS category and response. A budget impact model will be used to estimate the cost reduction in adjuvant chemotherapy as a result of 21-gene RS testing.

PRESENT ACCRUAL AND TARGET ACCRUAL

Target accrual is 75 in each of the neoadjuvant and adjuvant cohorts to total 150 patients.

Supported by Genomic Health.

Citation Format: Keegan NM, Milewski M, Kelly CM, Murphy V, Chao C, Walsh J, Kennedy MJ, O'Connor M, Murphy C, O'Reilly S, Keane M, Duffy K, Hennessy B, Morris PG. The impact of the 21 gene recurrence score (RS) on chemotherapy prescribing in estrogen receptor (ER) positive, lymph node positive early stage breast cancer in Ireland [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT3-04-03.

First isolation and outbreak of OXA-48-producing Klebsiella pneumoniae in an Irish hospital, March to June 2011

Five OXA-48-producing Klebsiella pneumoniae were detected in a tertiary referral hospital in Ireland between March and June 2011. They were found in the clinical isolates of five cases that were inpatients on general surgical wards. None of the cases had received healthcare at a facility outside of Ireland in the previous 12 months. This is the first report of OXA-48-producing K. pneumoniae in Ireland.

First isolation and outbreak of OXA-48-producing Klebsiella pneumoniae in an Irish hospital, March to June 2011

Five OXA-48-producing Klebsiella pneumoniae were detected in a tertiary referral hospital in Ireland between March and June 2011. They were found in the clinical isolates of five cases that were inpatients on general surgical wards. None of the cases had received healthcare at a facility outside of Ireland in the previous 12 months. This is the first report of OXA-48-producing K. pneumoniae in Ireland.

Enhancement strategies for Cu(II), Cr(III) and Cr(VI) remediation by a variety of seaweed species

Various chemical treatments have been applied to six brown, red and green seaweed species with a view to enhancing their metal removal for Cu(II), Cr(III) and Cr(VI). Treatment with acetone resulted in the greatest enhancement for both cationic and anionic species with relatively low mass losses (15-35%), indicating its low risk to biomass operational stability. Cation binding was increased by 69%, while the total Cr removal was augmented by 15%. Cr(VI) binding was shown to be an adsorption-coupled reduction, whereby Cr(VI) was bound to the biomass surface at pH 2 and subsequently reduced to Cr(III). Acetone treatment also resulted in biomasses that were capable of converting up to 83% of Cr(VI) in solution to Cr(III). Blocking of carboxyl and amino functionalities had significant negative effects both on total Cr removal as well as percentage conversion of Cr(VI) to Cr(III). Results therefore indicated the significant role played by these moieties in metal binding to these seaweeds. Potentiometric titrations displayed agreement between the degree of esterification and the decrease in Cu(II) removal for Ulva spp. and Polysiphonia lanosa. FTIR analysis identified changes in biomass functionality and availability after chemical modification, the results of which were in agreement with metal removal studies. In conclusion, these biosorbents represent suitable candidates to replace conventional removal technologies for metal bearing wastewaters, in particular for the detoxification of hazardous Cr(VI) waste streams.

Clinical trial: comparison of the gastrointestinal safety of lumiracoxib with traditional nonselective nonsteroidal anti-inflammatory drugs early after the initiation of treatment--findings from the Therapeutic Arthritis Research and Gastrointestinal Event Trial

BACKGROUND

The large (n = 18 325) Therapeutic Arthritis Research and Gastrointestinal Event Trial (TARGET) study demonstrated a significant gastrointestinal benefit with lumiracoxib 400 mg o.d. (4x the recommended dose in osteoarthritis) vs. naproxen 500 mg b.d. or ibuprofen 800 mg t.d.s.

AIM

To investigate how early a reduction in ulcer complications could be detected with lumiracoxib vs. nonselective nonsteroidal anti-inflammatory drugs in TARGET.

METHODS

Pointwise 95% confidence intervals were generated for the between-treatment differences in Kaplan-Meier estimates for definite or probable upper gastrointestinal ulcer complications (ulcer complications) and for all ulcers.

RESULTS

In patients not on aspirin, there was a significant reduction in all ulcers by day 8 and in ulcer complications by day 16 with lumiracoxib compared with both nonselective nonsteroidal anti-inflammatory drugs combined, by day 6 (all ulcers) and day 14 (ulcer complications) vs. naproxen and by day 32 (all ulcers) and day 33 (ulcer complications) vs. ibuprofen.

CONCLUSION

Even with short-term use, there are gastrointestinal safety benefits for lumiracoxib vs. nonselective nonsteroidal anti-inflammatory drugs.

Comparative study of chromium biosorption by red, green and brown seaweed biomass

Dried biomass of the macroalgae Fucus vesiculosus and Fucus spiralis (brown), Ulva spp. (comprising Ulva linza, Ulva compressa and Ulva intestinalis) and Ulva lactuca (green), Palmaria palmata and Polysiphonia lanosa (red) were studied in terms of their chromium biosorption performance. Metal sorption was highly pH dependent with maximum Cr(III) and Cr(VI) sorption occurring at pH 4.5 and pH 2, respectively. Extended equilibrium times were required for Cr(VI) binding over Cr(III) binding (180 and 120min, respectively) thus indicating possible disparities in binding mechanism between chromium oxidation states. The red seaweed P. palmata revealed the highest removal efficiency for both Cr(III) and Cr(VI) at low initial concentrations. However, at high initial metal concentrations F. vesiculosus had the greatest removal efficiency for Cr(III) and performed almost identically to P. lanosa in terms of Cr(VI) removal. The Langmuir Isotherm mathematically described chromium binding to the seaweeds where F. vesiculosus had the largest q(max) for Cr(III) sorption (1.21mmol g(-1)) and P. lanosa had the largest Cr(VI) uptake (0.88mmol g(-1)). P. palmata had the highest affinity for both Cr(III) and Cr(VI) binding with b values of 4.94mM(-1) and 8.64mM(-1), respectively. Fourier transform infrared analysis revealed interactions of amino, carboxyl, sulphonate and hydroxyl groups in chromium binding to Ulva spp. The remaining seaweeds showed involvement of these groups to varying degrees as well as ether group participation in the brown seaweeds and for Cr(VI) binding to the red seaweeds.

Pseudoautosomal gene: possible association with bipolar males but not with schizophrenia

The phenomenon of anticipation has been demonstrated in several neuropsychiatric disorders and suggested for schizophrenia and bipolar affective disorder. Many conditions exhibiting anticipation have been shown to be caused by trinucleotide repeat (CAG/CTG) expansions. Some evidence suggests that these expansions also exist in individuals with schizophrenia and bipolar affective disorder. In this investigation, we analysed a polymorphic CAG repeat in the interleukin receptor gene (IL9R), mapped to the pseudoautosomal region Xq28 and Yq21 (a candidate region for schizophrenia and affective disorder). Two common alleles, differing by one repeat unit and two rare alleles were found in cases and controls. Allele frequencies of this repeat were investigated in Irish schizophrenic, bipolar disorder and ethnically matched control samples. We found no evidence of an increased frequency of larger CAG repeats in either the schizophrenic or bipolar affective disorder samples as a whole when compared to the controls. However, dividing the samples by sex demonstrated a significant association between bipolar affective disorder males and the larger allele (allele 2) (patients 54.8% vs controls 40.1%, chi2 = 6.7, P = 0.009). In addition, a decreased frequency of this allele has been observed in the female patients, but did not attain statistical significance (patients 37% vs controls 46%, chi2 = 2.1, P = 0.14). This provides preliminary evidence that this locus or a closely mapped DNA variant (in linkage disequilibrium with the CAG repeat) may be involved in the genetic susceptibility to bipolar affective disorder in males.

No evidence to support the association of the potassium channel gene hSKCa3 CAG repeat with schizophrenia or bipolar disorder in the Irish population

Anticipation has attracted much interest and has been demonstrated in several neuropsychiatric disorders. For some disorders, this phenomenon has been found to correlate with the repeat number in large and unstable repeats (CAG/CTG). In addition, case control studies have suggested an increase in triplet repeat size in the psychoses. Recently, it was reported that the larger alleles (longer than 19 repeats) of the second potassium channel gene hSKCa3 are associated with schizophrenia in European and American samples. A similar trend, though not statistically significant, was also seen in bipolar disorder samples. This was further supported by an independent UK study.1 In this investigation, we have examined Irish familial schizophrenic patients, bipolar affective disorder patients and ethnically matched controls in an effort to replicate these findings. No significant differences between the patients and the control groups were observed. In addition, linkage analyses in the multiplex schizophrenic families showed no evidence for linkage or linkage disequilibrium. We concluded that the polymorphism of the second CAG repeat of the hSKCa3 gene is not a risk factor in schizophrenia or bipolar disorder, at least in the Irish population.

Synthesis and characterization of potent and selective agonists of the neuronal cannabinoid receptor (CB1)

Two subtypes of the cannabinoid receptor (CB1 and CB2) are expressed in mammalian tissues. Although selective antagonists are available for each of the subtypes, most of the available cannabinoid agonists bind to both CB1 and CB2 with similar affinities. We have synthesized two analogs of N-arachidonylethanolamine (AEA), arachidonylcyclopropylamide (ACPA) and arachidonyl-2-chloroethylamide (ACEA), that bind to the CB1 receptor with very high affinity (KI values of 2.2 +/- 0.4 nM and 1.4 +/- 0.3 nM, respectively) and to the CB2 receptor with low affinity (KI values of 0.7 +/- 0.01 microM and 3.1 +/- 1.0 microM, respectively). Both ACPA and ACEA have the characteristics of agonists at the CB1 receptor; both inhibit forskolin-induced accumulation of cAMP in Chinese hamster ovary cells expressing the human CB1 receptor, and both analogs increase the binding of [35S]GTPgammaS to cerebellar membranes and inhibit electrically evoked contractions of the mouse vas deferens. ACPA and ACEA produce hypothermia in mice, and this effect is inhibited by coadministration of the CB1 receptor antagonist SR141716A. Therefore, ACPA and ACEA are high-affinity agonists of the CB1 receptor but do not bind the CB2 receptor, suggesting that structural analogs of AEA can be designed with considerable selectivity for the CB1 receptor over the CB2 receptor.

Evidence for an allelic association between bipolar disorder and a Na+, K+ adenosine triphosphatase alpha subunit gene (ATP1A3)

BACKGROUND

Disturbances in central nervous system Na+, K+ adenosine triphosphatase (ATPase) activity have previously been proposed as being involved in the pathophysiology of bipolar mood disorder.

METHODS

We have examined one particular alpha subunit of this enzyme for allelic association in a sample of 85 Irish bipolar patients and 85 matched controls.

RESULTS

There was evidence for an overall allelic association between the disease and a dinucleotide polymorphism within the ATP1A3 gene (p = .022). Subjects were then analyzed on the basis of a number of criteria, and the significance of the association increased when cases were divided based on the nature of the first episode. Patients who presented with a depressive episode first showed a significant association (p = .001) with this polymorphism.

CONCLUSIONS

The results presented here provide preliminary evidence of an association between bipolar disorder and an alpha subunit of Na+, K+ ATPase, the expression of which predominates in the brain.

Amygdala-prefrontal interactions and conditioned bradycardia in the rabbit

Damage to the amygdala or medial prefrontal cortex (mPFC) produces deficits in learned autonomic adjustments. Whether connections between these 2 structures are necessary for acquiring classically conditioned heart rate (HR) decelerations was studied. Connections between them were interrupted by unilateral lesions of the mPFC and amygdala, but on opposite sides of the brain. One experiment focused on the mPFC and amygdala central nucleus and a second on the mPFC and amygdala basolateral complex. Bilateral lesions of either structure disrupted the HR conditioned response. The response of the 2 crossed lesioned groups also was smaller than that of the sham-operated and unilateral lesioned groups, but significant conditioned stimulus-evoked bradycardia occurred in both, suggesting that although interactions between the amygdala and mPFC may normally occur during associative emotional responding, these connections are not necessary for the acquisition of conditioned bradycardia.

Amygdala-prefrontal interactions and conditioned bradycardia in the rabbit

Damage to the amygdala or medial prefrontal cortex (mPFC) produces deficits in learned autonomic adjustments. Whether connections between these 2 structures are necessary for acquiring classically conditioned heart rate (HR) decelerations was studied. Connections between them were interrupted by unilateral lesions of the mPFC and amygdala, but on opposite sides of the brain. One experiment focused on the mPFC and amygdala central nucleus and a second on the mPFC and amygdala basolateral complex. Bilateral lesions of either structure disrupted the HR conditioned response. The response of the 2 crossed lesioned groups also was smaller than that of the sham-operated and unilateral lesioned groups, but significant conditioned stimulus-evoked bradycardia occurred in both, suggesting that although interactions between the amygdala and mPFC may normally occur during associative emotional responding, these connections are not necessary for the acquisition of conditioned bradycardia.

Distinct roles for leukemia inhibitory factor receptor alpha-chain and gp130 in cell type-specific signal transduction

Leukemia inhibitory factor (LIF) induces a variety of disparate biological responses in different cell types. These responses are thought to be mediated through the functional LIF receptor (LIFR), consisting of a heterodimeric complex of LIFR alpha-chain (LIFRalpha) and gp130. The present study investigated the relative capacity of the cytoplasmic domains of each receptor subunit to signal particular responses in several cell types. To monitor the signaling potential of LIFRalpha and gp130 individually, we constructed chimeric receptors by linking the extracellular domain of granulocyte colony-stimulating factor receptor (GCSFR) to the transmembrane and cytoplasmic regions of either LIFRalpha or gp130. Both chimeric receptors and the full-length GCSFR in expressed in M1 myeloid leukemic cells to measure differentiation induction, in embryonic stem cells to measure differentiation inhibition, and in Ba/F3 cells to measure cell proliferation. Our results demonstrated that whereas GCSFR-gp130 receptor homodimer mediated a GCSF-induced signal in all three cell types, the GCSFR-LIFRalpha receptor homodimer was only functional in embryonic stem cells. These findings suggest that the signaling potential of gp130 and LIFRalpha cytoplasmic domains may differ depending upon the tissue and cellular response initiated.

Risk factors for repeatedly reactive HIV-1 EIA and indeterminate western blots. A population-based case-control study

OBJECTIVE

Causes of indeterminate results of Western blot testing (IWB) for human immunodeficiency virus (HIV) type 1 include seroconversion, HIV-2 cross-reactivity, and autoimmune disease, but most IWB results remain unexplained. This case-control study assessed risk factors for IWB results, including early HIV infection, other retroviral infection, autoantibodies, and other medical conditions.

DESIGN

Prospective study to determine HIV seroconversion rate, with a case-control design to assess other risk factors for IWB. Cases (persons with one or more repeatedly reactive HIV-1 enzyme immunoassay with IWB), their current sexual partners, and controls (persons with negative enzyme immunoassay and Western blot results) were recruited from blood banks, health department and prenatal clinics, and private providers in Washington and Oregon.

RESULTS

Of 244 cases enrolled, 206 were followed up for 6 months or longer, and six (3.0%; 95% confidence interval [CI], 0.7% to 5.3%) with recent HIV risk behaviors seroconverted. The Western blot banding patterns differed among groups; cases usually had p17 or p24 bands, while controls and cases' sexual partners usually had polymerase bands. Conditional logistic regression indicated that independent risk factors for IWB among male cases and controls were a tetanus booster in the past 2 years (odds ratio, 3.2; 95% CI, 1.2 to 8.6) and sexual contact with a prostitute (odds ratio, 3.0; 95% CI, 1.0 to 9.5). Independent risk factors for women were parity (odds ratio, 1.2; 95% CI, 1.02 to 1.4) and autoantibodies, either rheumatoid factor or antinuclear antibodies (odds ratio, 2.3; 95% CI, 1.03 to 5.6). No cross-reactivity was detected with HIV-2, human T-lymphotrophic virus type 1, feline immunodeficiency or feline leukemia, or bovine immunodeficiency viruses.

CONCLUSIONS

Evaluation of persons with reactive HIV-1 enzyme immunoassays and IWB should include an assessment of HIV risk and other possible risk factors, such as alloimmunization (ie, parity or recent immunization) or autoantibodies (ie, antinuclear antibodies and rheumatoid factor). The relationship of IWB among men who reported sex with prostitutes is intriguing and warrants further study.

Intussusception in cystic fibrosis

Two cases of acute intussusception in older children with cystic fibrosis are reported. Both cases presented with symptoms and signs consistent with meconium ileus equivalent, which delayed the final diagnosis. Both cases required abdominal surgery but made full and uneventful recoveries.

Expression and characterization of the Ha-ras p21 protein produced at high levels in the insect/baculovirus system

Normal and mutated cDNAs of Ha-ras have each been cloned into a standard (pAc373) and a novel (p36C) baculovirus transfer vector and introduced via homologous recombination into the genome of Autographa californica nuclear polyhedrosis virus immediately downstream of the polyhedrin promoter. Spodoptera frugiperda cells infected with recombinant virus containing the normal Ha-ras gene express very high levels of ras p21 protein (approximately 20% of total cell protein), whereas the mutant protein was expressed at considerably lower levels. Molecular analysis showed that this was most likely due to a post-transcriptional event. The expression vector p36C produced considerably higher levels of recombinant p21 compared to the more commonly used pAc373. The majority of the normal ras p21 protein is soluble, cytoplasmic, and appears to be nonacylated. However, about 10% of the p21 associates with the membrane fraction of infected cells and migrates as a slightly faster band on gels. Furthermore, this band is sensitive to hydroxylamine treatment and shows specific incorporation of [3H]palmitate, strongly suggesting that it is the palmitoylated form of p21, which is the biologically active form of the protein. Both the soluble and membrane-associated p21 have been purified to homogeneity under nondenaturing conditions, the latter in the presence of detergents. The isolation of native palmitoylated p21 has not been reported previously. The difference in hydrophobicity between these two proteins has been demonstrated by Triton X-114 partitioning. The use of the insect/baculovirus expression system to express relatively high levels (20 mg/liter) of palmitoylated p21 should aid experiments to resolve the structural and functional properties of this molecule.

Pentylenetetrazol kindling in mice

Kindling with pentylenetetrazol to produce minimal and maximal convulsions was investigated in CF-1 mice. Like electrical kindling, the kindling effect was directly proportional to the dose or the intensity of the kindling stimulus. Similarly, the kindling effect was persistent, as was emphasized by the ability to kindle with an interdose interval of 3 days and by the convulsions produced by a challenge with pentylenetetrazol 30 days after withdrawal from the kindling treatment. The changes in excitability, associated with the kindling state, appeared to be relatively selective for pentylenetetrazol, because no changes in thresholds to either electroshock or administration of picrotoxin or N-methyl-DL-aspartate correlated temporally with the persistence of kindling. The influence of two anticonvulsant drugs, ethosuximide and cannabidiol, on kindling was also investigated. Both drugs blocked the development of kindling to pentylenetetrazol-induced minimal convulsions. Of these drugs, only ethosuximide raised the minimal convulsive threshold to pentylenetetrazol. Against pentylenetetrazol-induced kindling to maximal convulsions, only cannabidiol blocked kindling and only cannabidiol raised the maximal seizure threshold for pentylenetetrazol. Although the drugs modified the kindling effect, the mechanism of the interaction is not clear.