Inborn Errors of Immunity Contribute to the Burden of Skin Disease and Create Opportunities for Improving the Practice of Dermatology

Opportunities to improve the clinical management of skin disease are being created by advances in genomic medicine. Large-scale sequencing increasingly challenges notions about single-gene disorders. It is now apparent that monogenic etiologies make appreciable contributions to the population burden of disease and that they are underrecognized in clinical practice. A genetic diagnosis informs on molecular pathology and may direct targeted treatments and tailored prevention strategies for patients and family members. It also generates knowledge about disease pathogenesis and management that is relevant to patients without rare pathogenic variants. Inborn errors of immunity are a large class of monogenic etiologies that have been well-studied and contribute to the population burden of inflammatory diseases. To further delineate the contributions of inborn errors of immunity to the pathogenesis of skin disease, we performed a set of analyses that identified 316 inborn errors of immunity associated with skin pathologies, including common skin diseases. These data suggest that clinical sequencing is underutilized in dermatology. We next use these data to derive a network that illuminates the molecular relationships of these disorders and suggests an underlying etiological organization to immune-mediated skin disease. Our results motivate the further development of a molecularly derived and data-driven reorganization of clinical diagnoses of skin disease.

Estimating the heritability of SARS-CoV-2 susceptibility and COVID-19 severity

SARS-CoV-2 has infected over 340 million people, prompting therapeutic research. While genetic studies can highlight potential drug targets, understanding the heritability of SARS-CoV-2 susceptibility and COVID-19 severity can contextualize their results. To date, loci from meta-analyses explain 1.2% and 5.8% of variation in susceptibility and severity respectively. Here we estimate the importance of shared environment and additive genetic variation to SARS-CoV-2 susceptibility and COVID-19 severity using pedigree data, PCR results, and hospitalization information. The relative importance of genetics and shared environment for susceptibility shifted during the study, with heritability ranging from 33% (95% CI: 20%-46%) to 70% (95% CI: 63%-74%). Heritability was greater for days hospitalized with COVID-19 (41%, 95% CI: 33%-57%) compared to shared environment (33%, 95% CI: 24%-38%). While our estimates suggest these genetic architectures are not fully understood, the shift in susceptibility estimates highlights the challenge of estimation during a pandemic, given environmental fluctuations and vaccine introduction.

Development and implementation of a scalable and versatile test for COVID-19 diagnostics in rural communities

Rapid and widespread testing of severe acute respiratory coronavirus 2 (SARS-CoV-2) is essential for an effective public health response aimed at containing and mitigating the coronavirus disease 2019 (COVID-19) pandemic. Successful health policy implementation relies on early identification of infected individuals and extensive contact tracing. However, rural communities, where resources for testing are sparse or simply absent, face distinctive challenges to achieving this success. Accordingly, we report the development of an academic, public land grant University laboratory-based detection assay for the identification of SARS-CoV-2 in samples from various clinical specimens that can be readily deployed in areas where access to testing is limited. The test, which is a quantitative reverse transcription polymerase chain reaction (RT-qPCR)-based procedure, was validated on samples provided by the state laboratory and submitted for FDA Emergency Use Authorization. Our test exhibits comparable sensitivity and exceeds specificity and inclusivity values compared to other molecular assays. Additionally, this test can be re-configured to meet supply chain shortages, modified for scale up demands, and is amenable to several clinical specimens. Test development also involved 3D engineering critical supplies and formulating a stable collection media that allowed samples to be transported for hours over a dispersed rural region without the need for a cold-chain. These two elements that were critical when shortages impacted testing and when personnel needed to reach areas that were geographically isolated from the testing center. Overall, using a robust, easy-to-adapt methodology, we show that an academic laboratory can supplement COVID-19 testing needs and help local health departments assess and manage outbreaks. This additional testing capacity is particularly germane for smaller cities and rural regions that would otherwise be unable to meet the testing demand.

0541 Exploratory Study of Closed-Loop, Artificial Intelligence Driven Neurotechnology Improves Self-Reported Symptoms of Insomnia, Stress, and Anxiety in First Responders

Introduction

First responders (FR) have decreased life expectancy, attributed to work-related exposure to traumatic stress and circadian disruption. In prior studies, High-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM®) reduced symptoms and improved heart rate variability (HRV) in law enforcement personnel. HIRREM is operator dependent, difficult to scale, and many medications were excluded for prior studies. Cereset Research™ (CR) uses HIRREM core technology, echoing tones linked to brainwaves, with updated components, artificial intelligence (AI) driven protocols, and software management of designs to improve scalability. We report symptom changes in a series of first responders enrolled in an exploratory study evaluating CR for self-reported symptoms of insomnia, stress, or anxiety, including subjects taking previously excluded medications.

Methods

11 adults (4 females) meeting criteria for insomnia (ISI, of ≥8 points for ≥1 month), stress (PSS of ≥14), or anxiety (GAD-7 of ≥5), who are also FR, enrolled in this ongoing exploratory trial. Subjects receive six to twelve 60 minute sessions of CR, plus continued current care. Data collection is at baseline (V1), 0-21 days post-intervention (V2), 4-7 weeks later (V3), and 4-7 weeks thereafter (V4). Primary outcome is change in autonomic cardiovascular regulation at V3, with change in ISI, PSS, GAD-7, CES-D, and PCL-C as secondary outcomes. We report interim results for symptom outcomes at V3. HRV and baroreflex sensitivity results are pending.

Results

2 dropped out during follow-up. For n=9, median change from V1 to V3 ISI score: -6; PSS score: -4; GAD-7: -4; CES-D: -3; and PCL-C: -8. The cohort moved to no anxiety and low stress categories from V1 to V3.

Conclusion

Results suggest relevant symptom reductions among FR following use of CR, as seen previously with HIRREM for law enforcement, even with additional medications. This informs future randomized clinical trials using this scalable, non-drug intervention. Updated results will be presented.

Support: Support

Research grant received from, The Susanne Marcus Collins Foundation, Inc.

0542 Exploratory Use of Artificial Intelligence Driven Acoustic Neuromodulation Improved Sleep, Depression, Anxiety, and Stress in Adults with Persisting Post-Concussion Symptoms

Introduction

In prior studies, High-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM®) reduced persisting post-concussion symptoms (PPCS) of insomnia and depression and improved heart rate variability (HRV), but is operator dependent, with difficulty scaling. Cereset Research™ (CR), a noninvasive, closed-loop, artificial intelligence (AI) driven, acoustic neuromodulation technology uses the same core technology, echoing tones linked to brainwaves, but includes updated components, standardized AI driven protocols, software management of designs, and shorter sessions to improve scalability. This open label trial explores use of CR for PPCS.

Methods

5 adults (1 female, median age = 48, 31-64) with PPCS received a median of 8 CR sessions (range 7-9, 60 minutes each) over 11 (5-18) days as part of an open label IRB-approved exploratory study of CR for diverse health conditions. Data is collected at baseline (V1), 0-21 days (V2), 4-7 weeks later (V3), and 4-7 weeks thereafter (V4). Pre- and post-CR symptom inventories included concussion (RPQ), insomnia (ISI), depression (CES-D), anxiety (GAD-7), PTSD (PCL-C), and stress (PSS). Primary outcome is change in autonomics at V3 via HRV (SDNN and rMSSD) based on 10-minute BP and HR recordings using a BIOPAC device. Formal analysis of HRV outcome is pending, but we report preliminary changes in symptom outcomes.

Results

6 subjects have enrolled for sleep trouble related to PCCS, with 1 lost to follow-up after receiving intervention. For V1-V2 (n=5), median change in RPQ score is -23, ISI -10, CES-D -16, GAD-7 -7, PCL-C -16, and PSS -7. For V1-V3 (n=4), median change in RPQ -19, ISI -10.5, CES-D -6, GAD-7 -4.5, PCL-C -14.5, and PSS -3. No serious adverse events reported.

Conclusion

Preliminary results suggest similar, clinically meaningful reductions in ISI score, and concussion symptoms, as seen with HIRREM, suggesting promise as a scalable, non-drug intervention for insomnia with PPCS. Updated results will be presented.

Support: Support

Research grant received from, The Susanne Marcus Collins Foundation, Inc.

Decoupled molecular and inorganic framework dynamics in CH3NH3PbCl3

The organic-inorganic lead-halide perovskites are composed of organic molecules imbedded in an inorganic framework. The compounds with general formula CH3NH3PbX 3 (MAPbX 3) display large photovoltaic efficiencies for halogens X = Cl, Br, and I in a wide variety of sample geometries and preparation methods. The organic cation and inorganic framework are bound by hydrogen bonds that tether the molecules to the halide anions, and this has been suggested to be important to the optoelectronic properties. We have studied the effects of this bonding using time-of-flight neutron spectroscopy to measure the molecular dynamics in CH3NH3PbCl3 (MAPbCl3). Low-energy/high-resolution neutron backscattering reveals thermally activated molecular dynamics with a characteristic temperature of ~95 K. At this same temperature, higher-energy neutron spectroscopy indicates the presence of an anomalous broadening in energy (reduced lifetime) associated with the molecular vibrations. By contrast, neutron powder diffraction shows that a spatially long-range structural phase transitions occurs at 178 K (cubic → tetragonal) and 173 K (tetragonal → orthorhombic). The large difference between these two temperature scales suggests that the molecular and inorganic lattice dynamics in MAPbCl3 are actually decoupled. With the assumption that underlying physical mechanisms do not change with differing halogens in the organic-inorganic perovskites, we speculate that the energy scale most relevant to the photovoltaic properties of the lead-halogen perovskites is set by the lead-halide bond, not by the hydrogen bond.

Depth dependant element analysis of PbMg1/3Nb2/3O3 using muonic x-rays

The relaxor PbMg_1/3Nb_2/3O₃ (PMN) has received attention due to its potential applications as a piezoelectric when doped with PbTiO₃ (PT). Previous results have found that there are two phases existing in the system, one linked to the near-surface regions of the sample, the other in the bulk. However, the exact origin of these two phases is unclear. In this paper, depth dependant analysis results from negative muon implantation experiments are presented. It is shown that the Pb content is constant throughout all depths probed in the sample, but the Mg and Nb content changes in the near-surface region below 100 μm. At an implantation depth of 60 μm, it is found that there is a 25% increase in Mg content, with a simultaneous 5% decrease in Nb content in order to maintain charge neutrality. These results show that the previously observed skin effects in PMN are due to a change in concentration and unit cell.

CHILDSPLA: a collaboration between children and researchers to design and animate health states

AIM

The children's health state preferences learnt from animation (CHILDSPLA) project developed an interactive application presented on a touch screen device using an animated character to collect information from children about their health.

BACKGROUND

The underlying hypothesis was that health information could be directly collected from children as young as 4 years old by the use of animated characters. This paper describes in detail how children were involved in the development of the application, and recounts both the challenges and benefits of that process. A child psychologist and an animation filmmaker worked closely with children to design a character and to animate it to represent different health states. Children were recruited from a local primary school (n = 38) and a paediatric specialist hospital (n = 36). Diverse interactive activities were organized to help children give feedback and guide the design process. The activities for each session were adjusted to the children's needs, based on the experience of previous sessions.

RESULTS

The character and the animations were modified according to the feedback provided by the children.

CONCLUSIONS

Developing the CHILDSPLA app in collaboration with children was a worthwhile and enriching experience, despite the required iteration and extension of the design process, as it enabled us to adjust the tool to the children's needs.

Dark-adapted Pupil Sizes in a Prospective Evaluation of Laser in situ Keratomileusis Patients

PURPOSE

This study presents the results of scotopic pupil size measurement in a group of laser in situ keratomileusis (LASIK) patients and the implications this value has for night vision symptoms and treatment zones.

METHODS

This was a prospective study measuring the dark-adapted pupil of 218 patients using a handheld pupillometer.

RESULTS

The mean scotopic pupil size was 5.66 mm with a standard deviation of 1.04 mm. Pupils ranged in size from 3.00 mm to 9.00 mm.

CONCLUSION

Results suggest that a number of patients may have seotopic pupil size well beyond the treatment zones commonly used or available in refractive laser systems. Treating with an ablation zone that is smaller than the mesopic pupil will often result in night vision disturbances. Next generation technology such as the Nidek EC-5000 excimer laser can incorporate larger treatment diameters in order to reduce the incidence of halos and glare at night. [J Refract Surg 2000; 16(suppl):S239-S241].

A mortality risk model to adjust for case mix in UK paediatric cardiac surgery

Background

Congenital heart disease (CHD) is a relatively common disorder in childhood, affecting approximately 8–9 per 1000 live-born infants annually in the UK. CHD often involves serious abnormalities and is an important cause of childhood mortality, morbidity and disability. It is generally recognised that it is important and valuable to monitor outcomes in cardiac surgery and that, to do so fairly and effectively, one needs to risk stratify the case load of each unit. There is evidence that, since outcome monitoring in adult cardiac surgery became mandatory and routine, outcomes have improved. At present, no process for routinely monitoring risk-adjusted outcomes in paediatric cardiac surgery exists.

Objectives

To establish whether or not a risk model can be developed that is fit for the purpose of adjusting for case mix severity to facilitate routine monitoring of outcomes for paediatric cardiac surgery in the UK and to assess whether or not and how diagnostic information can augment procedural information in risk adjustment.

Methods

Data from the Central Cardiac Audit Database (CCAD) for all cardiac surgery procedures, excluding reoperations within 30 days, performed in the UK for patients < 16 years between 2000 and 2010 (38,597 patient episodes) were included: 70% for model development and 30% quarantined for validation. The outcome was 30-day survival, as supplied to CCAD through the Central Register of NHS patients (now the Medical Research Information Service). The CCAD defines 36 ‘specific procedures’. Nine of these were merged as a ‘low-volume specific procedure’ group (< 90 cases each in the entire development set). Unassigned cases were grouped as ‘not a specific procedure’. Twenty-four ‘primary’ cardiac diagnoses and separately a categorisation of ‘univentricular’ status were defined using a hierarchical algorithm developed by the study team based on International Paediatric and Congenital Cardiac codes. Comorbidities considered included prematurity (< 37 weeks' gestation), Down syndrome, constellations of features that constitute a recognised syndrome, congenital structural defects of organs other than the heart and acquired conditions. Other candidate variables included use of bypass and patient age, weight and sex. Data were analysed using logistic regression.

Results

In the development set, there were 25,665 episodes that resulted in survival to 30 days, 693 episodes for which the vital status at 30 days was unknown and 854 episodes that resulted in death within 30 days in the development set (mortality 3.2% overall). The risk model developed includes the following factors: specific procedure, primary cardiac diagnosis grouped into low-, medium- and high-risk categories, univentricular heart status, age band (neonate, infant, child), continuous age, continuous weight, presence of a comorbidity other than Down syndrome and use of bypass. To account for decreasing mortality over time in the development set, a binary indicator for operations performed after 1 January 2007 is also included in the model. We were able to calculate a risk score for 95% of cases in the test set: weight was missing in 5% of cases. Data completeness improved over time. The proposed model discriminated well: the area under the receiver operating characteristic curve (AUC) for the test set was 0.77 (0.81 for post-2007 data). Removal of all but procedural information gave a reduced AUC of 0.72. The model performed well across the spectrum of predicted risk in the entire data set, but there was underestimation of mortality risk in the test set among neonates operated from 2007.

Limitations

An important limitation is that the model pertains to short-term 30-day outcomes (not long-term outcomes) and is designed for the purpose of routine monitoring for quality assurance rather than bedside-type predictions for individual patients. Over the recent period in the validation set (since 2007), the model was found to underestimate risk at the very high-risk end (> 10% risk), in particular among neonates. This indicates that risk adjustment based on the current parameterisation of the model will potentially give an unduly negative impression of outcomes at those centres with a high proportion of high-risk cases. Finally, any risk model used for ongoing quality improvement initiatives needs to be regularly updated as data quality improves and clinical practice evolves.

Conclusions

For the first time diagnostic information has been successfully incorporated into risk adjustment for short-term outcomes in this patient group, which added discriminatory power. The risk model is fit for purpose, although the underestimation of risk in recent neonates is an important caveat. Several centres have expressed an interest in piloting the risk model and the accompanying monitoring tool. Future work includes developing software to generate variable life-adjusted display charts within units using the risk model; using the risk model to explore trends in case mix over time; and informing future work in evaluating long-term outcomes for children with CHD.

Funding

The National Institute for Health Research Health Services and Delivery Research programme.

Hormones, metabolites, and reproduction in Holsteins, Jerseys, and their crosses

Holsteins (HH), Jerseys (JJ), and their crosses in first (n=157) and second (n=107) lactation were used to determine if reproduction, progesterone (P4), insulin-like growth factor 1 (IGF-1), insulin, nonesterified fatty acids (NEFA), and milk production differed between genetic groups. Thirty-four cows were Holstein-Jersey (HJ) crosses, 46 were Jersey-Holstein (JH) crosses, 48 were purebred Holsteins (HH), and 29 were purebred Jerseys (JJ) in first lactation, whereas the second-lactation animals included 23 HJ, 35 JH, 35 HH, and 14 JJ. Blood samples were collected weekly for the first 10 wk postpartum. Analyses were conducted using the MIXED, chi-square, and GLIMMIX procedures (SAS Institute Inc., Cary, NC). Seasons of calving were cold (November to May) and hot (June to October) and were combined with year to form 8 year-seasons. Days open and number of services were affected by genetic group. The HH were open 169±8 d, which was greater than HJ (143±9 d), JJ (132±10 d), and JH (127±8 d). The HH had 2.4±0.1 services per pregnancy, which was greater than JH (1.9±0.1), but not different from HJ (2.1±0.2) or JJ (2.1±0.2). Concentrations of NEFA were greater in lactation 2 (0.52±0.02 mEq/L) than in lactation 1 (0.45±0.02 mEq/L) and decreased over the 10-wk period. Concentrations of NEFA were greater in the cold season except in yr 3. Insulin in lactation 1 (0.81±0.03 ng/mL) was greater than in lactation 2 (0.72±0.03 ng/mL); insulin decreased to wk 2 then gradually increased. The HJ had the greatest insulin concentrations (0.87±0.04 ng/mL) and the JJ had the lowest (0.66±0.04 ng/mL), and IGF-1 gradually increased over the 10-wk period. Milk production (actual yield in the first 305 d, not adjusted for fat and protein) was affected by genetic group, lactation number, year-season, and wk 1 insulin. The HH produced 10,348±207 kg of milk, which was greater than the HJ (9,129±230 kg), the JH (9,384±190 kg), and the JJ (7,080±240 kg). Milk production in lactation 2 (9,676±163 kg) was greater than that in lactation 1 (8,294±160 kg). The JJ (10.3±4.7%) had the highest frequency of mastitis. The chance of getting mastitis for HH (1.1±0.9%) differed from that for HJ (9.4±4.1%), JH (8.1±3.4%), and JJ (10.3±4.7%). Genetic group affected hormones and metabolites, which may partially explain differences in reproductive measures and milk yield.

First Report of Bean yellow mosaic virus in Alaska from Clover (Trifolium spp.)

In mid-June 2008, distinct mosaic leaves were observed on a cluster of clover (Trifolium spp.) with light pink and white flowers growing at the edge of a lawn in Palmer, AK. Virus minipurification from leaves of affected clover and protein extractions on a polyacrylamide electrophoresis implicated a ~35-kDa putative coat protein (CP). Subsequent western blots and ELISA with a universal potyvirus antiserum (Agdia Inc., Elkhart, IN) confirmed potyvirus identity. Total RNA extracts (RNeasy Plant Mini Kit, Qiagen Inc., Valencia, CA) from the same plant were used for reverse transcription (RT)-PCR. Three sets of degenerate primers that targeted potyvirus-specific genes, HC-Pro (helper component protease) and CI (cylindrical inclusion protein) and the genomic 3'-terminus that included a partial NIb (nuclear inclusion), CP (coat protein), and UTR (untranslated region), produced the expected PCR segments (~0.7, ~0.7, and ~1.6 kbp, respectively) on 1% agarose gels (1). Direct sequencing of the HC-Pro (GenBank No. GQ181115), CI (GQ181116), and CP (GU126690) segments revealed 98, 97, and 99% nucleotide identities (no gaps), respectively, to Bean yellow mosaic virus (BYMV)-chlorotic spot (CS) strain, GenBank No. AB373203. The next closest BYMV percent identity comparisons decreased to 79% for HC-Pro (GenBank No. DQ641248; BYMV-W), 79% for CI (U47033; BYMV-S) partial genes, and 96% for CP (AB041971; BYMV-P242). Mechanical inoculations of purified virus preparations produced local lesions on Chenopodium amaranticolor Coste & A. Reyn. (2 of 5) and C. quinoa Willd. (6 of 7), and mosaic on Nicotiana benthamiana Domin (5 of 5). BYMV was specifically confirmed on tester plants using a double-antibody sandwich (DAS)-ELISA BYMV (strain 204 and B25) kit (AC Diagnostics, Inc., Fayetteville, AR) as directed. The absence of another potyvirus commonly found in clover, Clover yellow vein virus (ClYVV), was verified in parallel DAS-ELISA ClYVV assays (AC Diagnostics, Inc). The BYMV isolate was maintained in N. benthamiana, and virion or sap extracts inoculated to the following host range (number of infected/total inoculated plants [verified by BYMV ELISA]): Cucumis sativus L. 'Straight Eight' (0/5), Gomphrena globosa L. (1/4), Nicotiana clevelandii A. Gray (4/7), Phaseolus vulgaris L. 'Bountiful' (1/3), Pisum sativum L. (Germplasm Resources Information Network Accession Nos. -PI 508092 (8/12), -W6 17525 (13/13), -W6 17529 (0/13), -W6 17530 (13/14), -W6 17537 (0/12), -W6 17538 (0/12), and -W6 17539 (0/21), Tetragonia tetragoniodes (2/2), Trifolium pretense L. 'Altaswede' (6/10), T. repens L. 'Pilgrim' (0/8), and Vicia faba L. (1/3). All infected plants had symptoms ranging from systemic mosaic (T. pretense, P. sativum) to leaf distortions (N. clevelandii, Tetragonia tetragoniodes). Interestingly, the host range and genomic sequences of the BYMV Alaskan strain resemble the BYMV-CS (chlorotic spot) strain that was originally isolated from a diseased red clover (T. pretense) plant in Japan more than 40 years ago (2). Although BYMV occurs worldwide and has a wide host range in dictoyledonous and monocotyledonous plants (3), to our knowledge, this is the first report of a natural occurrence of BYMV in Alaska. The incidence and distribution of BYMV in clover and other plant species are not known in Alaska. References: (1) C. Ha et al. Arch. Virol. 153:36, 2008. (2) H. Kume et al. Mem. Fac. Agric. Hokkaido Univ. 7:449, 1970. (3) S. J. Wylie et al. Plant Dis. 92:1596, 2008.

First Report of Tobacco rattle virus in Peony in Alaska

Peonies (Paeonia sp.) are highly valued for their large showy flowers in home gardens and commercially in the cut flower industry. In 2007, scattered peony (Paeonia lactiflora 'Sarah Bernhardt') plants cultivated on small plots at the University of Alaska Experimental Station in Fairbanks displayed distinct leaf ringspot patterns. Symptoms were more severe during the cooler months of the growing season (June and September), with symptom remission in the intervening warmer months. Leaf samples from six symptomatic plants were collected in July and from 20 symptomatic plants in September and assayed for viruses. Leaf samples (1 g) were assayed with a general protocol for plant virus extraction and partial purification with differential centrifugation followed by protein detection on stained sodium dodecyl sulfate-polyacrylamide gel electrophoresis (1). No distinct proteins indicative of viral coat protein(s) were detected. Tomato spotted wilt virus (TSWV) and Tobacco rattle virus (TRV), known pathogens of peony, were then specifically targeted. Total RNA was extracted from each sample with an RNeasy Plant Mini kit (Qiagen Inc., Valencia, CA) and used as the template for reverse transcription (RT)-PCR with random primers. TSWV was not detected by RT-PCR with tospovirus group-specific primers (Agdia, Inc., Elkhart, IN). A nested set of primers designed from the TRV 16-kDa protein gene on RNA1 (4) amplified an ~600-bp fragment from one of the symptomatic plants. This DNA was directly sequenced (GenBank Accession No. FJ357572) and BLAST searches in GenBank revealed as much as 95% nucleotide (nt) identity with TRV accessions J04347 and X03685. Additional primer pairs specific for TRV (2) amplified overlapping fragments with expected sizes of ~818, ~515, and ~290 bp from the 29- and 16-kDa protein genes on the 3'-end of RNA1 that were directly sequenced. Assembly of these sequences in Sequencher 4.8 (Gene Codes Corp., Ann Arbor, MI) resulted in a 1,422-nt sequence (Accession No. FJ357571) and Clustal X analysis (3) showed 93 to 94% nt identity to TRV isolates, -ORY (AF034622), -PpK20 (AF314165), -Pp085 (AJ586803), and -SYM (D00155). Mechanical inoculation of partially purified virions from the confirmed TRV-infected peony plant to Nicotiana benthamiana gave no symptoms to occasional ringspots, faintly curled leaves, and chlorotic blotches on N. tabacum 'Samsun', and local lesions on Chenopodium amaranticolor. TRV infection of these hosts was confirmed by RT-PCR. With electron microscopy, rod-shaped particles similar to TRV with a distinct central canal characteristic of TRV were seen occasionally only from inoculated N. benthamiana. On the basis of the biological and molecular data, we have determined the virus in the peony to be an isolate of TRV, tentatively named TRV-Peony. TRV was confirmed in only one other peony based on a sequenced 290-nt PCR fragment with 95% identity with the sequence from the other TRV-infected peony. Lack of TRV detection in the other symptomatic peonies was possibly due to low viral concentrations and interfering plant substances. Documentation of TRV in peonies is especially important to help avoid distribution of virus-infected vegetative propagation material. To our knowledge, this is the first report of TRV in this host in Alaska, but also of this virus in Alaska. References: (1) L. C. Lane. Methods Enzymol. 118:687, 1986. (2) D. J. Robinson. J. Phytopathol. 152:286, 2004. (3) J. D. Thompson et al. Nucleic Acids Res. 24:4882, 1997. (4) F. Van Der Wilk et al. Eur. J. Plant Pathol.100:109, 1994.

Identification and Molecular Characterization of a Potyvirus Isolated from Native Larkspur (Delphinium glaucum) in Alaska

Wild larkspur, Delphinium glaucum S. Watson, grows throughout most of Alaska along roadsides and in forests and is planted as an ornamental. Leaves containing distinct vein-clearing and chlorotic mosaic symptoms were first noticed on several D. glaucum plants during 2000 at the Georgeson Botanical Garden in Fairbanks, AK. Although affected plants continued to produce normal flowers, by 2008, the plants developed overall stunting. Initially, virus presence was determined by a general differential centrifugation extraction and concentration protocol followed by examination of the partially purified virus and leaf sap by electron microscopy. Filamentous particles approximately 725 nm long were observed. Virion protein extractions analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a putative coat protein (CP) of ~35 kDa. Potyvirus identity (family Potyviridae) was confirmed with universal potyvirus antiserum in western blots and ELISA assays (Agdia, Inc., Elkhart, IN). Exotic larkspur plants, D. elatum L., growing next to diseased D. glaucum plants, did not exhibit symptoms nor were they positive for potyvirus when tested serologically as described previously. Total RNA was extracted from potyvirus-infected leaves and used in reverse transcriptase-PCR assays that specifically targeted potyviruses (2,4) to generate genomic segments for identification and sequence analysis. Fragments representing portions of the helper component protease gene, HC-Pro (~700 bp), the cylindrical inclusion gene, CI (~700 bp), and the 3'-end (~1.7 kbp) were purified, cloned, sequenced, and deposited in GenBank (Accession Nos. FJ349329, FJ349328, and FJ349327, respectively). The sequenced 3'-end (1,674 nt) revealed a partial nuclear inclusion protein gene, NIb (1 to 630 nt), a CP gene (631 to 1,443 nt), and a 3'-untranslated region (1,447 to 1,674 nt) attached to a poly (A) tail. Blast searches in GenBank for percent identities of the nucleotide and amino acid comparisons resulted in highest similarities in conserved regions among members in the genus Potyvirus. For example, the highest CI, CP, and HP amino acid identities (0 gaps) were 67% with Potato virus A (Accession No. AF543709), 74% with Araujia mosaic virus (Accession No. EF710625), and 65% with Potato virus A (Accession No. AJ131403), respectively. However, none of the identities were sufficient for inclusion with an existing potyvirus species, whereby the CP amino acid sequence identity must be at least 80% (1). Mechanical transmission of purified virus to Chenopodium amaranticolor, C. quinoa, D. elatum, D. glaucum, and Nicotiana benthamiana seedlings was unsuccessful. We conclude that the isolated virus is a new species in the genus Potyvirus and propose the name Delphinium vein-clearing virus (DeVCV). To our knowledge, this is the first report of a virus isolated from D. glaucum and is representative of the growing number of viruses found in native plants (3). The distribution of DeVCV-infected larkspur is not known in managed or natural ecosystems. Identification of new viruses from native plants is important, in that, the host plant may act as a virus reservoir for transmission to other ornamental and crop plants. References: (1) P. H. Berger et al. Family Potyviridae. Page 819 in: Virus Taxonomy-8th Report of the ICTV. C. M. Fauquet et al., eds. Elsevier Academic Press, San Diego, CA, 2005. (2) J. Chen et al. Arch. Virol. 146:757, 2001. (3) I. Cooper and A. C. Jones. Adv. Virus Res. 67:1, 2006. (4) C. Ha et al. Arch. Virol. 153:25, 2008.

Delayed diagnosis of congenital heart disease worsens preoperative condition and outcome of surgery in neonates

OBJECTIVES

To assess whether the route by which neonatal congenital heart disease (CHD) is first recognised influences outcome after surgery.

METHODS

Surgical neonates admitted to a tertiary cardiac unit between March 1999 and February 2002 were retrospectively reviewed with analysis of risk factors for outcome. Three routes to initial recognition of CHD were compared: antenatal diagnosis, detection on the postnatal ward, and presentation after discharge to home. Outcome measures were mortality and duration of perioperative ventilation.

RESULTS

286 neonates had cardiac surgery with a median duration of ventilation of 101 h and in-hospital mortality of 12%. Recognition of CHD was antenatal in 20%, on the postnatal ward in 55% and after discharge to home in 25%. Multiple regression analyses, including the cardiac diagnosis, associated problems and other risk factors, indicated that severe cardiovascular compromise on admission to the cardiac unit was significantly related to mortality and prolonged ventilation. Considered in isolation, the route to recognition of heart disease did not influence mortality or ventilation time. Route to initial recognition did, however, influence the patient's condition on admission to the cardiac unit. Cardiovascular compromise and end organ dysfunction were least likely when recognition was antenatal and most common when presentation followed discharge to home.

CONCLUSION

The setting in which neonatal CHD is first recognised has an impact on preoperative condition, which in turn influences postoperative progress and survival after surgery. Optimal screening procedures and access to specialist care will improve outcome for neonates undergoing cardiac surgery.

Predicting outcome in ex-premature infants supported with extracorporeal membrane oxygenation for acute hypoxic respiratory failure

OBJECTIVE

To identify predictors of outcome in ex-premature infants supported with extracorporeal membrane oxygenation (ECMO) for acute hypoxic respiratory failure.

METHODS

Retrospective review of ex-premature infants with acquired acute hypoxic respiratory failure requiring ECMO support in the United Kingdom from 1992 to 2001. Review of follow up questionnaires completed by general practitioners and local paediatricians.

RESULTS

Sixty four ex-premature infants (5-10 each year) received ECMO support, despite increased use of advanced conventional treatments over the decade. The most common infective agent was respiratory syncytial virus (85% of cases). Median birth gestation was 29 weeks and median corrected age at the time of ECMO support was 42 weeks. Median ECMO support duration was relatively long, at 229 hours. Survival to hospital discharge and to 6 months was 80%, remaining similar throughout the period of review. At follow up, 60% had long term neurodisability and 79% had chronic pulmonary problems. Of pre-ECMO factors, baseline oxygen dependence, younger age, and inpatient status were associated with non-survival (p < or = 0.05). Of ECMO related factors, patient complications were independently associated with adverse neurodevelopmental outcome and death (p < 0.01).

CONCLUSIONS

Survival rates for ex-premature infants after ECMO support are favourable, but patients suffer a high burden of morbidity during intensive care and over the long term. At the time of ECMO referral, baseline oxygen dependence is the most important predictor of death, but no combination of the factors considered was associated with a mortality that would preclude ECMO support.

Cardiac ECMO for biventricular hearts after paediatric open heart surgery

OBJECTIVE

To delineate predictors of hospital survival in a large series of children with biventricular physiology supported with extracorporeal membrane oxygenation (ECMO) after open heart surgery.

RESULTS

81 children were placed on ECMO after open heart surgery. 58% (47 of 81) were transferred directly from cardiopulmonary bypass to ECMO. Hospital survival was 49% (40 of 81) but there were seven late deaths among these survivors (18%). Factors that improved the odds of survival were initiation of ECMO in theatre (64% survival (30 of 47)) rather than the cardiac intensive care unit (29% survival (10 of 34)) and initiation of ECMO for reactive pulmonary hypertension. Important adverse factors for hospital survival were serious mechanical ECMO circuit problems, renal support, residual lesions, and duration of ECMO.

CONCLUSIONS

Hospital survival of children with biventricular physiology who require cardiac ECMO is similar to that found in series that include univentricular hearts, suggesting that successful cardiac ECMO is critically dependent on the identification of hearts with reversible ventricular dysfunction. In our experience of postoperative cardiac ECMO, the higher survival of patients cannulated in the operating room than in the cardiac intensive care unit is due to early effective support preventing prolonged hypoperfusion and the avoidance of a catastrophic cardiac arrest.

Murine Scrapie Infection Causes an Abnormal Germinal Centre Reaction in the Spleen

Follicular dendritic cells (FDCs) of the lymphoreticular system play a role in the peripheral replication of prion proteins in some transmissible spongiform encephalopathies (TSEs), including experimental murine scrapie models. Disease-specific PrP (PrPd) accumulation occurs in association with the plasmalemma and extracellular space around FDC dendrites, but no specific immunological response has yet been reported in animals affected by TSEs. In the present study, morphology (light microscopical and ultrastructural) of secondary lymphoid follicles of the spleen were examined in mice infected with the ME7 strain of scrapie and in uninfected control mice, with or without immunological stimulation with sheep red blood cells (SRBCs), at 70 days post-inoculation or at the terminal stage of disease (268 days). Scrapie infection was associated with hypertrophy of FDC dendrites, increased retention of electron-dense material at the FDC plasma membrane, and increased maturation and numbers of B lymphocytes within secondary follicles. FDC hypertrophy was particularly conspicuous in immune-stimulated ME7-infected mice. The electron-dense material was associated with PrP Napoli accumulation, as determined by immunogold labelling. We hypothesize that immune system changes are associated with increased immune complex trapping by hypertrophic FDCs expressing PrP Napoli molecules at the plasmalemma of dendrites, and that this process is exaggerated by immune system stimulation. Contrary to previous dogma, these results show that a pathological response within the immune system follows scrapie infection.

Near-fatal grape aspiration with complicating acute lung injury successfully treated with extracorporeal membrane oxygenation

OBJECTIVE

In this report of a near-fatal case of grape aspiration successfully treated with extracorporeal membrane oxygenation (ECMO), we highlight the danger of feeding seedless grapes to young children and demonstrate that ECMO can provide cardiopulmonary support for cases of acquired large-airway disruption and can facilitate therapeutic intervention.

DESIGN

Case report.

SETTING

A tertiary pediatric intensive care unit and ECMO center.

PATIENT

A healthy 14-month-old boy aspirated a seedless grape while playing at home and suffered a cardiopulmonary arrest of 15 mins in duration. He responded to advanced life support with return of cardiac output but developed intractable cardiopulmonary failure secondary to aspirated grape particles and postobstructive pulmonary edema.

INTERVENTIONS

The patient was emergently transferred to the regional ECMO center and placed on venoarterial ECMO. Bronchoscopies were performed in the stable environment provided by ECMO, aspirated particles were removed from the large airways, and lung recovery was facilitated.

MEASUREMENTS AND MAIN RESULTS

End-organ perfusion was restored via ECMO during a period of severe intractable cardiopulmonary failure. Pulmonary recovery occurred during a 6-day ECMO run and was facilitated by therapeutic bronchoscopy. The patient was reviewed 1 yr later and has made a full neurodevelopmental recovery, despite a 15-min out-of-hospital cardiac arrest.

CONCLUSIONS

Aspiration of a seedless grape is a life-threatening event in a small child. This danger is not fully appreciated by parents in the UK. ECMO may be life saving in cases of acquired large-airway disruption resulting in severe cardiopulmonary failure, including foreign body aspiration, as long as end-organ perfusion is maintained.

Enzymatic activity of coenzyme B(12) derivatives with altered axial nucleotides: probing the mechanochemical triggering hypothesis in ribonucleotide reductase

Theoretical studies (J. Inorg. Biochem. 2001, 83, 121) of the involvement of the bulky 5,6-dimethylbenzimidazole (Dmbz) ligand of coenzyme B(12) (5'-deoxyadenosylcobalamin, AdoCbl) in the mechanism of activation of the carbon-cobalt bond of the coenzyme for homolytic cleavage by AdoCbl-dependent enzymes (the "mechanochemical triggering" mechanisms) have shown that a purely steric, ground-state mechanism can supply only a few kilocalories per mole (of the observed 13-16 kcal mol(-1)) of activation, but that an electronic mechanism, operating to stabilize the transition state, can explain all of the observed catalytic effect. To address these mechanisms experimentally, analogues of AdoCbl in which the Dmbz ligand is replaced by benzimidazole (Ado(Bzim)Cbl) or by imidazole (Ado(Im)Cbl) have been prepared and characterized. Both of these analogues support turnover in the AdoCbl-dependent ribonucleoside triphosphate reductase (RTPR) from Lactobacillus leichmannii at 100% of the activity of AdoCbl itself, but the Ado(Im)Cbl analogue has a significantly higher K(m). 5'-Deoxyadenosylcobinamide, the analogue in which the axial nucleotide has been chemically removed, in contrast, is inactive in the spectrophotometric assay, which indicates that it has at most 1% of the activity of AdoCbl. Stopped-flow spectrophotometric measurements of the formation of cob(II)alamin at the enzyme active site show that RTPR binds Ado(Bzim)Cbl slightly more weakly than it does AdoCbl, but binds Ado(Im)Cbl 8-fold more weakly. While the equilibrium constant for cob(II)alamin formation is nearly the same for Ado(Bzim)Cbl and AdoCbl, it is 5-fold smaller for Ado(Im)Cbl. Finally, the forward rate constant for enzyme-induced Co-C bond homolysis was about the same for Ado(Bzim)Cbl and for AdoCbl but was 17-fold smaller for Ado(Im)Cbl. These results are consistent with a small contribution from ground-state mechanochemical triggering, but they do not in themselves rule out transition-state mechanical triggering.

Role of sulfation in CD44-mediated hyaluronan binding induced by inflammatory mediators in human CD14(+) peripheral blood monocytes

Activation of T cells by Ag or stimulation of monocytes with inflammatory cytokines induces CD44 to bind to hyaluronan (HA), an adhesion event implicated in leukocyte-leukocyte, leukocyte-endothelial cell, and leukocyte-stromal cell interactions. We have previously shown that TNF-alpha induces CD44 sulfation in a leukemic cell line, which correlated with the induction of HA binding and CD44-mediated adhesion. In this study, we establish that TNF-alpha and IFN-gamma induce HA binding and the sulfation of CD44 in CD14(+) PBMC, whereas no induced HA binding or CD44 sulfation was observed in CD14(-) PBMC stimulated with TNF-alpha. Treatment of cells with NaClO(3), an inhibitor of sulfation, prevented HA binding in a significant percentage of CD14(+) PBMC induced by TNF-alpha, LPS, IL-1beta, or IFN-gamma. Furthermore, stimulation with TNF-alpha or IFN-gamma in the presence of NaClO(3) reduced the ability of isolated CD44H to bind HA, demonstrating a direct effect of CD44H sulfation on HA binding. In contrast, the transient induction of HA binding in T cells by PHA was not affected by NaClO(3), suggesting that activated T cells do not use sulfation as a mechanism to regulate HA binding. Overall, these results demonstrate that inducible sulfation of CD44H is one mechanism used by CD14(+) peripheral blood monocytes to induce HA binding in response to inflammatory agents such as TNF-alpha and IFN-gamma.

Equilibrium and kinetic studies on the reactions of alkylcobalamins with cyanide

Ligand substitution equilibria of different alkylcobalamins (RCbl, R = Me, CH(2)Br, CH(2)CF(3), CHF(2), CF(3)) with cyanide have been studied. It was found that CN(-) first substitutes the 5,6-dimethylbenzimidazole (Bzm) moiety in the alpha-position, followed by substitution of the alkyl group in the beta-position trans to Bzm. The formation constants K(CN) for the 1:1 cyanide adducts (R(CN)Cbl) were found to be 0.38 +/- 0.03, 0.43 +/- 0.03, and 123 +/- 9 M(-1) for R = Me, CH(2)Br, and CF(3), respectively. In the case of R = CH(2)CF(3), the 1:1 adduct decomposes in the dark with CN(-) to give (CN)(2)Cbl. The unfavorable formation constants for R = Me and CH(2)Br indicate the requirement of very high cyanide concentrations to produce the 1:1 complex, which cause the kinetics of the displacement of Bzm to be too fast to follow kinetically. The kinetics of the displacement of Bzm by CN(-) could be followed for R = CH(2)CF(3) and CF(3) to form CF(3)CH(2)(CN)Cbl and CF(3)(CN)Cbl, respectively, in the rate-determining step. Both reactions show saturation kinetics at high cyanide concentration, and the limiting rate constants are characterized by the activation parameters: R = CH(2)CF(3), DeltaH = 71 +/- 1 kJ mol(-1), DeltaS = -25 +/- 4 J K(-1) mol(-1), and DeltaV = +8.9 +/- 1.0 cm(3) mol(-1); R = CF(3), DeltaH = 77 +/- 3 kJ mol(-1), DeltaS = +44 +/- 11 J K(-1) mol(-1), and DeltaV = +14.8 +/- 0.8 cm(3) mol(-1), respectively. These parameters are interpreted in terms of an I(d) and D mechanism for R = CH(2)CF(3) and CF(3), respectively. The results of the study enable the formulation of a general mechanism that can account for the substitution behavior of all investigated alkylcobalamins including coenzyme B(12).

Human papillomavirus type 16 E6 and E7 cooperate to increase epidermal growth factor receptor (EGFR) mRNA levels, overcoming mechanisms by which excessive EGFR signaling shortens the life span of normal human keratinocytes

Epidermal growth factor receptor (EGFR) levels are dramatically increased in human keratinocytes (HKc) immortalized with full-length human papillomavirus type 16 (HPV16) DNA (HKc/HPV16), but increases in EGFR levels actually precede immortalization. In some normal HKc strains, acute expression of HPV16 E6 (but not HPV16 E5, HPV16 E7, or HPV6 E6) from LXSN retroviral vectors produced an increase in EGFR mRNA levels detectable at 24 h and stable for up to 10 days after infection. However, about one-half of the individual normal HKc strains we analyzed proved unresponsive to E6 induction of EGFR mRNA despite the robust expression of E6 and degradation of p53. E6 responsiveness of normal HKc strains correlated inversely with initial EGFR levels: although HKc strains expressing relatively low basal EGFR levels grew poorly and tolerated the infection protocol with difficulty, they responded to E6 with an increase in EGFR mRNA and protein and with robust proliferation. However, those HKc strains expressing high basal EGFR levels grew well, but did not respond to E6 with increased EGFR levels or with proliferation. Immunostaining of paraffin-embedded foreskin tissue for the EGFR confirmed that there is an intrinsic interindividual variability of EGFR expression in HKC: These results prompted us to investigate the effects of overexpression of the EGFR in normal HKC: Infection of normal HKc with a LXSN retrovirus expressing the full-length human EGFR cDNA resulted in a dramatic reduction in growth rate and a shorter life span. Although acute expression (1-10 days after infection) of HPV16 E7 alone did not induce the EGFR, acute expression of E6 and E7 together increased EGFR levels in normal HKc unresponsive to E6 alone. Also, HKc infected with E7 alone expressed increased EGFR levels at early stages of extended life span (at passage 9 after infection), and HKc immortalized by HPV16 E7 alone expressed EGFR levels comparable with those of E6/E7-immortalized cells. These results support a key role of the EGFR in HPV16-mediated transformation of HKC: In addition, these data show that normal HKc do not tolerate excessive EGFR levels/signaling, and such intolerance must be overcome in order for HKc to become immortalized by HPV16. We conclude that both E6 and E7 contribute to increasing EGFR levels, but with different mechanisms: although E6 can increase EGFR levels, it cannot overcome the resistance of normal HKc to excessive EGFR signaling. On the other hand E7, which alone does not acutely increase EGFR mRNA or protein, allows for EGFR overexpression in normal HKC:

Follicular dendritic cells in scrapie pathogenesis

Scrapie pathogenesis was studied in chimaeric mice that carried the prion protein (PrP) gene only in particular cells of the immune system. These mice were produced by grafting bone marrow from PrP expressing donors into PrP deficient recipients and vice versa. As follicular dendritic cells are not replaced significantly from the bone marrow in adult mice, this procedure resulted in a mismatch in PrP genotype between these cells and bone marrow derived cells such as lymphocytes. Using these models we obtained strong evidence that follicular dendritic cells produced high levels of the normal form of PrP in uninfected mice. Furthermore, the replication of a mouse-passaged scrapie strain in the spleen depended only on the presence of PrP expressing follicular dendritic cells. PrP expression by lymphocytes or other bone marrow derived cells had no influence on replication in spleen or on neuroinvasion in these models. These results indicate that the follicular dendritic cell is a potential target for prophylactic or therapeutic intervention in transmissible spongiform encephalopathies.

Cellular and sub-cellular localisation of PrP in the lymphoreticular system of mice and sheep

Using immunocytochemistry or immunogold electron microscopy, abnormal PrP accumulation was found in lymphoreticular tissues of Suffolk sheep naturally exposed to scrapie and in the spleens of ME7 infected C57 BL mice at 70 days after infection and at the terminal stage of disease at 170 days. Clinically diseased scrapie affected sheep show widespread PrP accumulation within tingible body macrophages (TBMs) and follicular dendritic cells (FDCs) of secondary lymphoid follicles. Serial tonsillar biopsies taken from 171 ARQ/ARQ sheep at 4 months of age did not contain abnormal PrP accumulations but 80% of biopsies were positive by 14 months. In contrast, whole body necropsies of sheep not previously biopsied failed to detect PrP in the tonsil of sheep at 4, 8, 12 or 16 months of age. These findings suggest that the biopsy procedure of susceptible sheep but not resistant sheep may induce tonsillar infection. In spleen of mice both at 70 and 170 dpi, accumulations of PrP were found within lysosomes of TBMs and also at the plasma-lemma of FDCs. In the light zone of follicles of terminally diseased mice, all FDC dendrites were arranged in the form of highly reactive or hyperplastic labrynthine glomerular complexes. PrP was consistently seen between FDC dendrites in association with abundant electron dense antigen-antibody complexes. At 70 days after challenge, labrynthine complexes were rare and invariably labelled for PrP. However, sparse PrP labelling was also seen on simple FDC dendrites at this stage. These observations suggests that scrapie infected FDCs continually release PrP from the cell surface where it accumulates in excess in association with trapped immune complexes and dendritic extension. It is likely that TBMs acquire lysosomal PrP following phagocytosis of effete FDC processes or from the extracellular space. We suggest that the normal function of PrP may involve cell process extension or immune complex trapping.

Fetal cell grafts provide long-term protection against scrapie induced neuronal loss

We have transplanted fetal neurons to prolong hippocampal pyramidal cell survival in a mouse scrapie model in which 50% of CA1 pyramidal cells have died by day 180 of the 250-day incubation period. Cells prepared from embryonic PrP deficient mice were intracerebrally injected into infected mice on day 150 and groups killed on day 171 and with terminal disease. Neuron counts and CA1 depth measurements were made on semi-serial sections using an image analysis system. Both grafted groups retained more CA1 neurons than controls injected with medium alone, and showed greater depth of CA1 than controls. This new approach may have potential as a late-stage therapy for TSEs for which there are currently no available treatments.

Molecular modeling of the mechanochemical triggering mechanism for catalysis of carbon-cobalt bond homolysis in coenzyme B12

The possible contributions of the mechanochemical triggering effect to the enzymatic activation of the carbon-cobalt bond of coenzyme B12 (5'-deoxyadenosylcobalamin, AdoCbl) for homolytic cleavage have been studied by molecular modeling and semiempirical molecular orbital calculations. Classically, this effect has envisioned enzymatic compression of the axial Co-N bond in the ground state to cause upward folding of the corrin ring and subsequent sterically induced distortion of the Co-C bond leading to its destabilization. The models of this process show that in both methylcobalamin (CH3Cbl) and AdoCbl, compression of the axial Co-N bond does engender upward folding of the corrin ring, and that the extent of such upward folding is smaller in an analog in which the normal 5,6-dimethylbenzimidazole axial ligand is replaced by the sterically smaller ligand, imidazole (CH3(lm)Cbl and Ado(lm)Cbl). Furthermore, in AdoCbl, this upward folding of the corrin is accompanied by increases in the carbon-cobalt bond length and in the Co-C-C bond angle (which are also less pronounced in Ado(Im)Cbl), and which indicate that the Co-C bond is indeed destabilized by this mechanism. However, these effects on the Co-C bond are small, and destabilization of this bond by this mechanism is unlikely to contribute more than ca. 3 kcal mol(-1) towards the enzymatic catalysis of Co-C bond homolysis, far short of the observed ca. 14 kcal mol(-1). A second version of mechanochemical triggering, in which compression of the axial Co-N bond in the transition state for Co-C bond homolysis stabilizes the transition state by increased Co-N orbital overlap, has also been investigated. Stretching the Co-C bond to simulate the approach to the transition state was found to result in an upward folding of the corrin ring, a slight decrease in the axial Co-N bond length, a slight displacement of the metal atom from the plane of the equatorial nitrogens towards the "lower" axial ligand, and a decrease in strain energy amounting to about 8 kcal mol(-1) for both AdoCbl and Ado(Im)Cbl. In such modeled transition states, compression of the axial Co-N bond to just below 2.0 A (the distance subsequently found to provide maximal stabilization of the transition state by increased orbital overlap) required about 4 kcal mol(-1) for AdoCbl, and about 2.5 kcal mol(-1) for Ado(Im)Cbl. ZINDO/1 calculations on slightly simplified structures showed that maximal electronic stabilization of the transition state by about 10 kcal mol(-1) occurred at an axial Co-N bond distance of 1.96 A for both AdoCbl and Ado(Im)Cbl. The net result is that this type of transition state mechanochemical triggering can provide 14 kcal mol(-1) of transition state stabilization for AdoCbl, and about 15.5 kcal mol(-1) for the Ado(Im)Cbl, enough to completely explain the observed enzymatic catalysis. These results are discussed in the light of current knowledge about class I AdoCbl-dependent enzymes, in which the coenzyme is bound in its "base-off" conformation, with the lower axial ligand position occupied by the imidazole moiety of an active site histidine residue, and the class II enzymes, in which AdoCbl binds to the enzyme in its "base-on" conformation, and the pendent 5,6-dimethylbenzimidazole base remains coordinated to the metal during Co-C bond activation.

Resection, rotationplasty, and femoropelvic arthrodesis in severe congenital femoral deficiency. A report of the surgical technique and three cases

BACKGROUND

The major problems associated with severe congenital deficiency of the femur are an unstable hip joint and a femur that is more than 50% shorter than the contralateral, normal femur. The usual treatment of these extreme cases of congenital femoral deficiency is a Syme or Boyd amputation when the child begins to walk. A knee fusion is done when the child is older, and the patient functions as an above-the-knee amputee. Rotationplasty has been described as an alternative treatment that allows the patient to function as a below-the-knee amputee. None of the currently described types of rotationplasty address the problem of the unstable hip.

METHODS

Three patients with severe congenital femoral deficiency underwent a unique single-stage reconstruction. In this procedure, the limb is completely detached except for the sciatic nerve and the femoral vessels. The proximal part of the dysplastic femur and some muscles are resected. The residual limb is externally rotated 180 degrees and the rotated distal part of the femur is fused to the pelvis. All of the muscles distal to the knee remain undisturbed.

RESULTS

The anatomical knee in its rotated position functioned as a hip with flexion and extension, and the femoropelvic arthrodesis provided a more stable support. The rotated ankle acted as a knee, and the patients functioned as below-the-knee amputees. The duration of follow-up of these three patients was eight, six, and four years. Active hip flexion was 10 degrees to 70 degrees , 10 degrees to 90 degrees , and 0 degrees to 80 degrees , and active knee flexion was 900 and 95 . The patients' gait continued to improve as they matured.

CONCLUSIONS

The femoropelvic arthrodesis provides a stable hip. Since the muscles distal to the knee are not disturbed, the problem of derotation of the limb, which is often seen following the Van Nes rotationplasty, is not seen after this operation.

A microbiological evaluation of warm air hand driers with respect to hand hygiene and the washroom environment

A finger rinse technique for counting micro-organisms on hands showed no significant difference in the level of recovered micro-organisms following hand drying using either warm air or paper towels. Contact plate results appeared to reflect the degree of dampness of hands after drying rather than the actual numbers of micro-organisms on the hands. In laboratory tests, a reduction in airborne count of Pseudomonas aeruginosa and Staphylococcus aureus of between 40 and 75% was achieved from 600 readings comparing inlets and outlets of warm air hand driers. In washroom trials, the number of airborne micro-organisms was reduced by between 30 and 75%. Air emitted from the outlet of the driers contained significantly fewer micro-organisms than air entering the driers. Drying of hands with hand driers was no more likely to generate airborne micro-organisms than drying with paper towels. Levels of micro-organisms on external surfaces of hand driers were not significantly different to those on other washroom surfaces. This work shows that warm air hand driers, of the type used in this study, are a hygienic method of drying hands and therefore appropriate for use in both the healthcare and food industry.

Dipeptide seryl-histidine and related oligopeptides cleave DNA, protein, and a carboxyl ester

The amino acids histidine (His) and serine (Ser), or amino acids similar to Ser, function together as key catalytic amino acids in the active sites of such diverse enzymes as the serine- and thiol-proteases, lipases, and esterases. Ser and His are also conserved in the intein-extein junctions of the phylogenetically widespread self-splicing proteins and at the N- and C-termini of the homing endonucleases spliced from them. Here we show that the dipeptide seryl-histidine (Ser-His) and related oligopeptides can themselves cleave DNA, protein, and the ester p-nitrophenyl acetate (p-NPA) over wide ranges of pH and temperature. Denaturing polyacrylamide gel electrophoresis (PAGE) of 5'-end labeled DNA samples incubated with Ser-His reveals a pattern of two bands per nucleotide position, consistent with the generation of both 3'-hydroxyl and 3'-phosphate DNA cleavage fragments, as would be expected of phosphodiester hydrolysis by Ser-His. To the best of our knowledge, Ser-His is the shortest peptide ever reported to show cleavage activity with multiple categories of natural substrates. The amenability of the dipeptide to variation through addition of amino acid residues, either internally or to the C-terminus while retaining its multiple cleavage activities, combined with its reactivity over wide ranges of pH and temperature, demonstrates the evolutionary capacity of the Ser/His dyad and evokes many questions about possible roles it may have played in molecular evolution and its potential role as a core for selection of oligopeptides with enhanced cleavage activities and target specificity.

Follicular dendritic cells in TSE pathogenesis

The pathogenesis of transmissible spongiform encephalopathies (TSEs) often includes a replication phase in lymphoid tissues before infection spreads to the central nervous system. Recent studies show that the follicular dendritic cells of the germinal centres are critical for this replication. These cells are therefore potential targets for therapy or prophylaxis in natural TSEs, such as variant Creutzfeldt-Jakob disease.

Translation/secretion coupling by type III secretion systems

Type III secretion systems mediate export of virulence proteins and flagellar assembly subunits in Gram-negative bacteria. Chaperones specific to each class of secreted protein are believed to prevent degradation of the secreted substrates. We show that an additional role of chaperones may be to regulate translation of secreted proteins. We show that the chaperone FIgN is required for translation of the flgM gene transcribed from one mRNA transcript (a flagellar class 3 transcript), but not from another (a flagellar class 2 transcript). FIgM translated from the class 3 transcript is primarily secreted whereas FIgM translated from the class 2 transcript is primarily retained in the cytoplasm. These results suggest FIgM and other type III secretion substrates possess both mRNA and amino acid secretion signals, and supports a new role for type III chaperones in translation/secretion coupling.

Sites of prion protein accumulation in scrapie-infected mouse spleen revealed by immuno-electron microscopy

Prion protein (PrP) from the brains of animals with transmissible spongiform encephalopathies is partially protease resistant (PrP(res)) compared with fully sensitive PrP (PrP(sen)) from uninfected brains. In most experimental models, PrP(res) is a reliable indicator of infectivity. Light microscopic studies have suggested that both PrP(sen) and disease-specific accumulations of PrP are associated with follicular dendritic cells (FDCs). Using immunogold electron microscopy, this study has demonstrated disease-specific accumulation of PrP in the spleens of C57 BL mice, 70 days after intracerebral infection with the ME7 strain of scrapie and at the terminal stage of disease at 170 days. At both stages, tingible body macrophages contained PrP within lysosomes and PrP was also detected at the plasmalemma of FDCs. In the light zone of follicles of terminally diseased mice, all FDC dendrites were arranged in the form of highly reactive or hyperplastic labyrinthine glomerular complexes, within which PrP was consistently seen between FDC processes in association with abundant electron dense material, interpreted as antigen-antibody complexes. Within some glomeruli, fibrillar forms of PrP consistent with amyloid were seen. At 70 days after challenge, large or hyperplastic labyrinthine complexes were rare and invariably labelled for PrP. However, sparse PrP labelling was also seen on simple FDC processes at this stage. The ubiquitous accumulation of extracellular PrP in complex glomerular dendrites of FDCs in spleens from terminally affected mice, contrasted with simple FDC profiles, sparse PrP and limited electron dense deposits in all but a few FDCs of 70-day post-infected mice. This suggests that FDCs continually release PrP from the cell surface, where it is associated with trapped antigen-antibody complexes and dendritic extension. It is likely that tingible body macrophages acquire PrP following phagocytosis of PrP within iccosomes or from the extracellular space around FDC dendrites. These studies would not support an intracellular phase of PrP accumulation in FDCs but show that PrP is produced in excess by scrapie-infected cells from where it is released into the extracellular space. We suggest that PrP(sen) is involved in dendritic extension or in the process of antibody-antigen trapping, perhaps as part of the binding mechanism for antigen-antibody complexes. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.

Detection of PrP in extraneural tissues

Transmissible spongiform encephalopathies (TSEs) or "prion diseases" are a group of unconventional fatal diseases. TSEs are characterised by the accumulation of a modified form of the normal host glycoprotein, PrP (PrP(c)). In the course of infection PrP(c) is converted to an abnormally protease resistant form, PrP(Sc). The exact nature of the infectious agent responsible for these diseases remains controversial. While there is compelling evidence that TSE agents contain an informational molecule, possibly a nucleic acid, some believe that the infectious agent or "prion" is solely composed of PrP(Sc). Nevertheless, PrP is required for TSE pathogenesis, as mice devoid of the PrP gene (PrP(-/-)) remain healthy when challenged with TSE isolates and are unable to replicate infectivity within the central nervous system (CNS) or in other tissues. In recent years immunocytochemistry has been used to pinpoint which cells are associated with abnormal accumulations of PrP, providing important information on the cellular targeting of TSE infection. In uninfected and scrapie-infected mice, PrP protein is found in the CNS and in extraneural tissues such as spleen and lymph nodes. In the peripheral lymphoid system, PrP is associated with follicular dendritic cells that are known to be important for replication of infectivity for at least one TSE strain. This review will focus on current methods for the immunocytochemical detection of PrP in murine extraneural tissues, mainly lymphoid tissues, and will discuss recent findings on the role of the peripheral lymphoid system in TSE pathogenesis.

Pharmacokinetics, tolerability, and clinical effectiveness of quetiapine fumarate: an open-label trial in adolescents with psychotic disorders

BACKGROUND

This is the first investigation of the pharmacokinetics, tolerability, and efficacy of quetiapine fumarate in adolescents with chronic or intermittent psychotic disorders.

METHOD

Ten patients with DSM-IV chronic or intermittent psychotic disorders (ages 12.3 through 15.9 years) participated in an open-label, rising-dose trial and received oral doses of quetiapine twice daily (b.i.d.), starting at 25 mg b.i.d. and reaching 400 mg b.i.d. by day 20. The trial ended on day 23. Key assessments were pharmacokinetic analysis of plasma quetiapine concentrations and neurologic, safety, and efficacy evaluations.

RESULTS

No statistically significant differences were observed between 100-mg b.i.d. and 400-mg b.i.d. quetiapine regimens for total body clearance, dose-normalized area under the plasma concentration-time curve, or dose-normalized premorning- or postmorning-dose trough plasma values obtained under steady-state conditions after multiple-dose regimens. No unexpected side effects occurred with quetiapine therapy, and no statistically significant changes from baseline were observed for the UKU Side Effect Rating Scale items that were rated. No serious adverse events or clinically important changes in hematology or clinical chemistry variables were reported. The most common adverse events were postural tachycardia and insomnia. Extrapyramidal side effects improved, as evidenced by significant (p < .05) decreases from baseline to endpoint in the mean Simpson-Angus Scale total scores and Barnes Akathisia Scale scores. Quetiapine improved positive and negative symptoms, as shown by significant (p < .05) decreases from baseline to endpoint in the mean Brief Psychiatric Rating Scale total score, the Clinical Global Impressions-Severity of Illness scale, and the Modified Scale for the Assessment of Negative Symptoms summary score.

CONCLUSION

Quetiapine pharmacokinetics were dose proportional in adolescents and were similar to those previously reported for adults. Quetiapine was well tolerated and effective in the small number of adolescents studied.

A role for the cell adhesion molecule CD44 and sulfation in leukocyte-endothelial cell adhesion during an inflammatory response?

CD44 is a widely expressed cell adhesion molecule that has been implicated in a variety of biological processes including lymphopoiesis, angiogenesis, wound healing, leukocyte extravasation at inflammatory sites, and tumor metastasis. The adhesive function of CD44, like other molecules involved in inducible adhesion, is tightly regulated. Post-translational modifications, isoform expression, aggregation state, and protein associations all can affect the ligand binding properties of CD44, and these can vary depending on the cell type and the activation state of the cell. The most extensively characterized ligand for CD44 is hyaluronan, a component of the extracellular matrix. Interactions between CD44 and hyaluronan can mediate both cell-cell and cell-extracellular matrix adhesion. In the immune system, both the selectin molecules and CD44 have been implicated in the initial binding of leukocytes to endothelial cells at an inflammatory site. Sulfation is required for selectin-mediated leukocyte-endothelial cell interactions, and, recently, inducible sulfation also was shown to regulate CD44-mediated leukocyte adhesion to endothelial cells. Sulfation, therefore, may be important in the regulation of cell adhesion at inflammatory sites. In this commentary we have reviewed the molecular aspects of CD44 and the mechanisms that regulate its binding to hyaluronan. In addition, we have summarized the role of CD44 and hyaluronan in mediating leukocyte-endothelial cell interactions and have discussed how this interaction may be regulated. Finally, we examined the potential role of sulfation as an inducible means to regulate CD44-mediated leukocyte adhesion and as a more general mechanism to regulate leukocyte-endothelial cell interactions.

Control of bacterial spores

Bacterial spores are much more resistant than their vegetative counterparts. The most dangerous spore-former is Clostridium botulinum which produces a potent neurotoxin that can prove fatal. The most common food poisoning from a spore-former is caused by C. perfringens. Other food poisoning spore-formers include Bacillus cereus, B. subtilis and B. licheniformis. There are a number of non-pathogenic spore-formers including butyric and thermophilic anaerobes that cause significant economic losses to food producers. Some unusual spoilage complaints have been reported, for example, B. sporothermodurans in UHT milk, Alicyclobacillus acidoterrestris in apple and orange juice and Desulfotomaculum nigrificans in hot vending machines. Control of spore-formers requires an understanding of both the resistance and outgrowth characteristics of the spores.

Scrapie replication in lymphoid tissues depends on prion protein-expressing follicular dendritic cells

The immune system is central in the pathogenesis of scrapie and other transmissible spongiform encephalopathies (TSEs) or 'prion' diseases. After infecting by peripheral (intraperitoneal or oral) routes, most TSE agents replicate in spleen and lymph nodes before neuroinvasion. Characterization of the cells supporting replication in these tissues is essential to understanding early pathogenesis and may indicate potential targets for therapy, for example, in 'new variant' Creutzfeldt-Jakob disease. The host 'prion' protein (PrP) is required for TSE agent replication and accumulates in modified forms in infected tissues. Abnormal PrP is detected readily on follicular dendritic cells (FDCs) in lymphoid tissues of patients with 'new variant' Creutzfeldt-Jakob disease, sheep with natural scrapie and mice experimentally infected with scrapie. The normal protein is present on FDCs in uninfected mice and, at lower levels, on lymphocytes. Studies using severe combined immunodeficiency (SCID) mice, with and without bone marrow (BM) grafts, have indicated involvement of FDCs and/or lymphocytes in scrapie pathogenesis. To clarify the separate roles of FDCs and lymphocytes, we produced chimeric mice with a mismatch in PrP status between FDCs and other cells of the immune system, by grafting bone marrow from PrP-deficient knockout mice into PrP-expressing mice and vice versa. Using these chimeric models, we obtained strong evidence that FDCs themselves produce PrP and that replication of a mouse-passaged scrapie strain in spleen depends on PrP-expressing FDCs rather than on lymphocytes or other bone marrow-derived cells.

Thermolysis of coenzymes B12 at physiological temperatures: activation parameters for cobalt-carbon bond homolysis and a quantitative analysis of the perturbation of the homolysis equilibrium by the ribonucleoside triphosphate reductase from Lactobacillus leichmannii

The kinetics of the thermolysis of 5'-deoxyadenosylcobalamin (AdoCbl, coenzyme B12) in aqueous solution, pH 7.5, have been studied in the temperature range 30-85 degrees C using AdoCbl tritiated at the adenine C2 position and the method of initial rates. Combined with a careful analysis of the distribution of adenine-containing products, the results permit the dissection of the competing rate constants for carbon-cobalt bond homolysis and heterolysis. After correction for the temperature-dependent occurrence of the much less reactive base-off species of AdoCbl, the activation parameters for homolysis of the base-on species were found to be delta H++homo,on = 33.8 +/- 0.2 kcal mol-1 and delta S++homo,on = 13.5 +/- 0.7 cal mol-1 K-1, values not significantly different from those determined by Hay and Finke (J. Am. Chem. Soc. 108 (1986) 4820), in the temperature range 85-115 degrees C. In contrast, the heterolysis of base-on AdoCbl was characterized by a much smaller enthalpy of activation (delta H++het,on = 18.5 +/- 0.2 kcal mol-1) and a negative entropy of activation (delta S++het,on = -34.0 +/- 0.7 cal mol-1 K-1) so that heterolysis, which is minor pathway at elevated temperatures, is the dominant pathway for AdoCbl decomposition at physiological temperatures. Using literature values for the rate constant for the reverse reaction, the equilibrium constant for AdoCbl homolysis at 37 degrees C was calculated to be 7.9 x 10(-18). Comparison with the equilibrium constant for this homolysis at the active site of the ribonucleoside triphosphate reductase from Lactobacillus leichmannii shows that the enzymes shifts the equilibrium constant towards homolysis products by a factor of 2.9 x 10(12) (17.7 kcal mol-1) by binding the thermolysis products with an equilibrium constant of 7.1 x 10(16) M-2, compared to the bonding constant for AdoCbl of 2.4 x 10(4) M-1.

Cholinergic effects on human gastric motility

BACKGROUND

Cholinergic regulation of chronotropic (frequency) and inotropic (force) aspects of antral contractility and how these impact on gastric emptying are not well delineated.

AIMS

To determine the effects of cholinergic stimulation and inhibition on myoelectric, contractile, and emptying parameters of gastric motility.

METHODS

Ten normal subjects underwent three studies each, using simultaneous electrogastrography (EGG), antroduodenal manometry, and gastric emptying with dynamic antral scintigraphy (DAS). After 30 minutes of baseline fasting manometry and EGG, subjects received saline intravenously, atropine (0.6 mg then 0.25 mg/hour intravenously), or bethanechol (5 mg subcutaneously). This was followed by another 30 minutes' recording and by three hours of postprandial recording after ingestion of a technetium-99m labelled solid meal.

RESULTS

During fasting, atropine decreased, whereas bethanechol increased, the antral manometric motility index and EGG power. Postprandially, atropine decreased the amplitude of antral contractions by DAS, decreased the postprandial antral manometric motility index, and slowed gastric emptying. Atropine caused a slight increase in postprandial frequency of antral contractions by DAS and gastric myoelectrical activity by EGG. Bethanechol slightly increased the amplitude, but slightly decreased the frequency of antral contractions by DAS and decreased the frequency of gastric myoelectrical activity by EGG, with no significant increase in the motility index or gastric emptying.

CONCLUSIONS

Cholinergic antagonism with atropine reduces antral contractility and slows gastric emptying. Cholinergic stimulation with bethanechol increases antral contractility, but decreases the frequency of antral contractions, without altering the antral motility index or gastric emptying.

Carbamazepine hypersensitivity and the use of lymphocyte proliferation responses

This report describes a case of multisystem failure in a 5-year-old boy who was being treated with carbamazepine for a seizure disorder. Carbamazepine hypersensitivity was diagnosed from the combination of the clinical constellation and the results of the patient's peripheral blood monocyte proliferation responses to both carbamazepine and a panel of other medications.

An unusual etiology of biliary hilar obstruction and the potential role of acidic fibroblast growth factor in the development of a biliary neuroma

Neuroma of the biliary tract is a rare condition thought to be caused by trauma secondary to cholecystectomy. More rare is the occurrence that causes symptomatic biliary obstruction. A 65-year-old woman was hospitalized because of abdominal pain, nausea, vomiting, and general malaise of 1 to 2 months duration. Cholecystectomy had been performed 40 years before. Ultrasound revealed hepatomegaly and dilated intrahepatic ducts. CT showed intra- and extrahepatic ductal dilatation with questionable intraductal mass. Endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography demonstrated stricture of the hepatic duct bifurcation. The biliary bifurcation was resected, and hepaticojejunostomy was performed. The patient's postoperative course was unremarkable. Histological examination of the surgical specimen revealed positive staining for the S-100 antigen of the obstructing luminal stricture (without evidence of cholangiocarcinoma), which was consistent with a biliary neuroma. Positive staining was also found for acidic (and not basic) fibroblast growth factor (FGF) and two of its high affinity receptors (FGFR-1 and FGFR-4). This study supports the apparent association between biliary neuromas and cholecystectomy as well as the potential role of an established angiogenic and neurogenic growth factor in the formation of this tumor. Finally, this case is also unique in that it represents the longest interval between cholecystectomy and presentation of a biliary neuroma, 40 years after surgery.

Cauda equina syndrome. Implications for the orthopaedic nurse in a clinical setting

Cauda equina syndrome (CES) is a presentation of signs and symptoms that indicate nerve compression involving one or more of the nerve roots in the lumbar spine. The Clinical Nurse Specialist working in a general orthopaedic practice must become familiar with the presentation of CES to appropriately assess the patient and alert the physician. Prompt and accurate care of the patient is critical when cauda equina syndrome is suspected to minimize permanent nerve damage. This article describes the syndrome, its signs and symptoms, basic triage techniques, plan of care, and recovery for the patient with cauda equina syndrome.

Heteronuclear NMR studies of cobalt corrinoids. 20. 31P chemical shift anisotropy of aquacobalamin and its complex with a haptocorrin from chicken serum

Static light scattering measurements have been used to determine the molecular mass (65.3 kDa) and second virial coefficient (3.66 x 10(-4) mol mL g-2) for the complex between chicken serum haptocorrin (HC) and aquacobalamin (H2OCbl). Dynamic light scattering measurements have also been used to determine the translational diffusion coefficient of the H2OCbl-HC complex as a function of concentration. From the diffusion coefficient at infinite dilution (4.71 x 10(-7) cm2 s-1), the hydrodynamic radius (45.5 A) and rotational correlation time (85.4 ns) have been calculated. Using the latter, and measured values of the 31P NMR linewidths of the H2OCbl-HC complex at several field strengths, a detailed analysis of the 31P nuclear relaxation is possible. The chemical shift anisotropy term from the transverse relaxation equation is determined to be 95.7 ppm, and the average phosphorus-proton internuclear distance is 2.05 A. For comparison to protein-free H2OCbl, the chemical shift anisotropy of the phosphorus atom was studied by solid state NMR spectroscopy and the 31P relaxation by solution T1 measurements. These studies give values of 110.3 ppm for the chemical shift anisotropy term and 2.45 A for the average phosphorus-proton internuclear distance. The results are consistent with a significant change in the conformation of the H2OCbl phosphodiester upon binding to haptocorrin which could be due to a shortening of the axial Co-N bond.

Structural and enzymatic studies of a new analogue of coenzyme B12 with an alpha-adenosyl upper axial ligand

A new analogue of coenzyme B12 (5'-deoxyadenosylcobalamin, AdoCbl), in which the configuration of the N-glycosidic bond in the Ado ligand is inverted [(alpha-ribo)AdoCbl], has been synthesized and its crystal structure determined by X-ray diffraction [MoKalpha, lambda = 0.71073 A, monoclinic P212121, a = 16.132(12) A, b = 21. 684(15) A, c = 27.30(3) A, 9611 independent reflections, R1 = 0. 0708]. As suggested by molecular mechanics modeling before the structure was known, the Ado ligand lies over the southern quadrant of the molecule, as is the case for AdoCbl. The most striking feature of the structure is disorder in the orientation of the adenine (Ade) moiety relative to the ribose of the Ado ligand. This was resolved with a two-state model in which in the major (0.57 occupancy) conformer the A16(O)-A11-A9(N)-A8 dihedral angle is 1.9 degrees and the Ade is virtually perpendicular to the corrin ring; in the minor conformer, the Ade is tilted down, and this dihedral is -48.7 degrees. The Co-C and axial Co-N bond lengths and the Co-C-C bond angle are quite similar to those in AdoCbl. The corrin ring is considerably flatter than that of AdoCbl, with a fold angle of 11.7 degrees. The molecule was successfully modeled by molecular mechanics (MM), and rotation of the Ado ligand relative to the corrin gave rise to four locally minimum structures with the Ado in the southern, eastern, northern, or western quadrant, with the southern conformation as the global minimum, as is the case with AdoCbl itself. Nuclear Overhauser effects (nOe's) observed by two-dimensional (2D) NMR were incorporated as restraints in molecular dynamics (MD) and simulated annealing (SA) calculations. A MD simulation at 300 K showed that only the southern conformation is populated with the Ado ligand confined to an arc from over C15 to over C12, while the Ade ring oscillates from perpendicular to parallel to the corrin ring. Twenty-seven structures were collected by MD-SA. Most of these annealed into the southern conformation, but examples of the other conformations were also found. The new analogue is a partially active coenzyme for the ribonucleotide reductase from Lactobacillus leichmanii with maximal activity that is 9.7% of that of AdoCbl itself, and a very high Km value (245 microM compared to 0.54 microM for AdoCbl). In addition, the rate constant for enzyme-induced carbon-cobalt bond cleavage of (alpha-ribo)AdoCbl is 160-fold smaller than that for AdoCbl, and only 1/3 as much cob(II)alamin is produced at the active site.

Absence of detectable EWS/FLI1 expression after therapy-induced neural differentiation in Ewing sarcoma

Ewing sarcoma and other peripheral primitive neuroectodermal tumors (pPNETs) display limited neural differentiation and are thought to have a neural crest origin Greater than 95% of these tumors share common t(11;22)(q24;q12) ort(21;22)(q22;q12) chromosomal translocations leading to ES/FLI1 or EWS/ERG gene fusions, respectively. The resulting chimeric oncoproteins seem to function as aberrant transcription factors. However, whether these molecules contribute to the limited neural differentiation observed in pPNETs or actually inhibit differentiation remains unclear. We report a Ewing sarcoma case from the forearm of a 10-year-old girl which expressed EWS/FLI1 fusion transcripts. The tumor was treated with surgery, chemotherapy, and local radiation, but residual tumor was detected within a year as a well-differentiated peripheral neural tumor lacking detectable EWS/FLI1 expression. Further studies suggested that the primary and residual tumors were clonally related. This association between apparent therapy-induced differentiation in Ewing sarcoma and absence of detectable fusion transcripts in the residual tumor provides presumptive evidence that EWS/FLI1 expression may inhibit differentiation in tumour cells.

Effect of gastric acid suppressants on human gastric motility

BACKGROUND

The effect of histamine H2 receptor antagonists on gastric emptying is controversial.

AIMS

To determine the effects of ranitidine, famotidine, and omeprazole on gastric motility and emptying.

PATIENTS AND METHODS

Fifteen normal subjects underwent simultaneous antroduodenal manometry, electrogastrography (EGG), and gastric emptying with dynamic antral scintigraphy (DAS). After 30 minutes of fasting manometry and EGG recording, subjects received either intravenous saline, ranitidine, or famotidine, followed by another 30 minutes recording and then three hours of postprandial recording after ingestion of a radiolabelled meal. Images were obtained every 10-15 minutes for three hours to measure gastric emptying and assess antral contractility. Similar testing was performed after omeprazole 20 mg daily for one week.

RESULTS

Fasting antral phase III migrating motor complexes (MMCs) were more common after ranitidine (9/15 subjects, 60%), famotidine (12/15, 80%), and omeprazole (8/12, 67%) compared with placebo (4/14, 29%; p < 0.05). Postprandially, ranitidine, famotidine, and omeprazole slowed gastric emptying, increased the amplitude of DAS contractions, increased the EGG power, and increased the antral manometric motility index.

CONCLUSIONS

Suppression of gastric acid secretion with therapeutic doses of gastric acid suppressants is associated with delayed gastric emptying but increased antral motility.

Severely combined immunodeficient (SCID) mice resist infection with bovine spongiform encephalopathy

Following combined intraperitoneal and intracerebral injection with bovine spongiform encephalopathy (BSE) cow brain homogenate, SCID mice show a resistance to infection in comparison with immunocompetent CB20 mice. BSE occurred in only five out of 22 challenged SCID mice, with a mean incubation period of 573 days, whereas all the CB20 mice developed the disease with a mean incubation period of 456 days. In contrast, previous studies have shown that intracerebral infection of SCID mice with a mouse-passaged scrapie strain, ME7, produces 100% incidence of disease but no replication of infectivity in spleen. The results with BSE suggest that there is little or no direct infection of the CNS in interspecies transmissions, but that processing or replication of infectivity in peripheral lymphoid tissues may facilitate subsequent spread of infection to the CNS.