Deeply Virtual Compton Scattering Cross Section at High Bjorken x_{B}

We report high-precision measurements of the deeply virtual Compton scattering (DVCS) cross section at high values of the Bjorken variable x_{B}. DVCS is sensitive to the generalized parton distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton form factors (CFFs) of the nucleon as a function of x_{B}, while systematically including helicity flip amplitudes. In particular, the high accuracy of the present data demonstrates sensitivity to some very poorly known CFFs.

Determination of the ^{27}Al Neutron Distribution Radius from a Parity-Violating Electron Scattering Measurement

We report the first measurement of the parity-violating elastic electron scattering asymmetry on ^{27}Al. The ^{27}Al elastic asymmetry is A_{PV}=2.16±0.11(stat)±0.16(syst)  ppm, and was measured at ⟨Q^{2}⟩=0.02357±0.00010  GeV^{2}, ⟨θ_{lab}⟩=7.61°±0.02°, and ⟨E_{lab}⟩=1.157  GeV with the Q_{weak} apparatus at Jefferson Lab. Predictions using a simple Born approximation as well as more sophisticated distorted-wave calculations are in good agreement with this result. From this asymmetry the ^{27}Al neutron radius R_{n}=2.89±0.12  fm was determined using a many-models correlation technique. The corresponding neutron skin thickness R_{n}-R_{p}=-0.04±0.12  fm is small, as expected for a light nucleus with a neutron excess of only 1. This result thus serves as a successful benchmark for electroweak determinations of neutron radii on heavier nuclei. A tree-level approach was used to extract the ^{27}Al weak radius R_{w}=3.00±0.15  fm, and the weak skin thickness R_{wk}-R_{ch}=-0.04±0.15  fm. The weak form factor at this Q^{2} is F_{wk}=0.39±0.04.

Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q^{2}) up to 15.75  (GeV/c)^{2}. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q^{2} and double the range over which a longitudinal or transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q^{2} and attributed to hard two-photon exchange (TPE) effects, extending to 8  (GeV/c)^{2} the range of Q^{2} for which a discrepancy is established at >95% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q^{2}.

Deep Exclusive Electroproduction of π^{0} at High Q^{2} in the Quark Valence Regime

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of x_{B} (0.36, 0.48, and 0.60) and Q^{2} (3.1 to 8.4  GeV^{2}) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions dσ_{T}/dt+εdσ_{L}/dt, dσ_{TT}/dt, dσ_{LT}/dt, and dσ_{LT^{'}}/dt are extracted as a function of the proton momentum transfer t-t_{min}. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross section throughout this kinematic range. The data are well described by calculations based on transversity generalized parton distributions coupled to a helicity flip distribution amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

Precision Measurement of the Beam-Normal Single-Spin Asymmetry in Forward-Angle Elastic Electron-Proton Scattering

A beam-normal single-spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable related to the imaginary part of the two-photon exchange process. We report a 2% precision measurement of the beam-normal single-spin asymmetry in elastic electron-proton scattering with a mean scattering angle of θ_{lab}=7.9° and a mean energy of 1.149 GeV. The asymmetry result is B_{n}=-5.194±0.067(stat)±0.082 (syst) ppm. This is the most precise measurement of this quantity available to date and therefore provides a stringent test of two-photon exchange models at far-forward scattering angles (θ_{lab}→0) where they should be most reliable.

Enhanced contact investigations for nine early travel-related cases of SARS-CoV-2 in the United States

Coronavirus disease 2019 (COVID-19), the respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first identified in Wuhan, China and has since become pandemic. In response to the first cases identified in the United States, close contacts of confirmed COVID-19 cases were investigated to enable early identification and isolation of additional cases and to learn more about risk factors for transmission. Close contacts of nine early travel-related cases in the United States were identified and monitored daily for development of symptoms (active monitoring). Selected close contacts (including those with exposures categorized as higher risk) were targeted for collection of additional exposure information and respiratory samples. Respiratory samples were tested for SARS-CoV-2 by real-time reverse transcription polymerase chain reaction at the Centers for Disease Control and Prevention. Four hundred four close contacts were actively monitored in the jurisdictions that managed the travel-related cases. Three hundred thirty-eight of the 404 close contacts provided at least basic exposure information, of whom 159 close contacts had ≥1 set of respiratory samples collected and tested. Across all actively monitored close contacts, two additional symptomatic COVID-19 cases (i.e., secondary cases) were identified; both secondary cases were in spouses of travel-associated case patients. When considering only household members, all of whom had ≥1 respiratory sample tested for SARS-CoV-2, the secondary attack rate (i.e., the number of secondary cases as a proportion of total close contacts) was 13% (95% CI: 4-38%). The results from these contact tracing investigations suggest that household members, especially significant others, of COVID-19 cases are at highest risk of becoming infected. The importance of personal protective equipment for healthcare workers is also underlined. Isolation of persons with COVID-19, in combination with quarantine of exposed close contacts and practice of everyday preventive behaviors, is important to mitigate spread of COVID-19.

Enhanced contact investigations for nine early travel-related cases of SARS-CoV-2 in the United States

Coronavirus disease 2019 (COVID-19), the respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first identified in Wuhan, China and has since become pandemic. In response to the first cases identified in the United States, close contacts of confirmed COVID-19 cases were investigated to enable early identification and isolation of additional cases and to learn more about risk factors for transmission. Close contacts of nine early travel-related cases in the United States were identified and monitored daily for development of symptoms (active monitoring). Selected close contacts (including those with exposures categorized as higher risk) were targeted for collection of additional exposure information and respiratory samples. Respiratory samples were tested for SARS-CoV-2 by real-time reverse transcription polymerase chain reaction at the Centers for Disease Control and Prevention. Four hundred four close contacts were actively monitored in the jurisdictions that managed the travel-related cases. Three hundred thirty-eight of the 404 close contacts provided at least basic exposure information, of whom 159 close contacts had ≥1 set of respiratory samples collected and tested. Across all actively monitored close contacts, two additional symptomatic COVID-19 cases (i.e., secondary cases) were identified; both secondary cases were in spouses of travel-associated case patients. When considering only household members, all of whom had ≥1 respiratory sample tested for SARS-CoV-2, the secondary attack rate (i.e., the number of secondary cases as a proportion of total close contacts) was 13% (95% CI: 4-38%). The results from these contact tracing investigations suggest that household members, especially significant others, of COVID-19 cases are at highest risk of becoming infected. The importance of personal protective equipment for healthcare workers is also underlined. Isolation of persons with COVID-19, in combination with quarantine of exposed close contacts and practice of everyday preventive behaviors, is important to mitigate spread of COVID-19.

Clinical and virologic characteristics of the first 12 patients with coronavirus disease 2019 (COVID-19) in the United States

Data on the detailed clinical progression of COVID-19 in conjunction with epidemiological and virological characteristics are limited. In this case series, we describe the first 12 US patients confirmed to have COVID-19 from 20 January to 5 February 2020, including 4 patients described previously^1-3. Respiratory, stool, serum and urine specimens were submitted for SARS-CoV-2 real-time reverse-transcription polymerase chain reaction (rRT-PCR) testing, viral culture and whole genome sequencing. Median age was 53 years (range: 21-68); 8 patients were male. Common symptoms at illness onset were cough (n = 8) and fever (n = 7). Patients had mild to moderately severe illness; seven were hospitalized and demonstrated clinical or laboratory signs of worsening during the second week of illness. No patients required mechanical ventilation and all recovered. All had SARS-CoV-2 RNA detected in respiratory specimens, typically for 2-3 weeks after illness onset. Lowest real-time PCR with reverse transcription cycle threshold values in the upper respiratory tract were often detected in the first week and SARS-CoV-2 was cultured from early respiratory specimens. These data provide insight into the natural history of SARS-CoV-2. Although infectiousness is unclear, highest viral RNA levels were identified in the first week of illness. Clinicians should anticipate that some patients may worsen in the second week of illness.

Poly(amido amine) dendrimers as absorption enhancers for oral delivery of camptothecin

Oral delivery of camptothecin has a treatment advantage but is limited by low bioavailability and gastrointestinal toxicity. Poly(amido amine) or PAMAM dendrimers have shown promise as intestinal penetration enhancers, drug solubilizers and drug carriers for oral delivery in vitro and in situ. There have been very limited studies in vivo to evaluate PAMAM dendrimers for oral drug delivery. In this study, camptothecin (5 mg/kg) was formulated and co-delivered with cationic, amine-terminated PAMAM dendrimer generation 4.0 (G4.0) (100 and 300 mg/kg) and anionic, carboxylate-terminated PAMAM generation 3.5 (G3.5) (300 and 1000 mg/kg) in CD-1 mice. Camptothecin associated to a higher extent with G4.0 than G3.5 in the formulation, attributed to an electrostatic interaction on the surface of G4.0. Both PAMAM G4.0 and G3.5 increased camptothecin solubilization in simulated gastric fluid and caused a 2-3 fold increase in oral absorption of camptothecin when delivered at 2 h. PAMAM G4.0 and G3.5 did not increase mannitol transport suggesting that the oral absorption of camptothecin was not due to tight junction modulation. Histologic observations of the epithelial layer of small intestinal segments of the gastrointestinal tract (GIT) at 4 h post dosing supported no evidence of toxicity at the evaluated doses of PAMAM dendrimers. This study demonstrates that both cationic (G.4) and anionic (G3.5) PAMAM dendrimers were effective in enhancing the oral absorption of camptothecin. Results suggest that drug inclusion in PAMAM interior controlled solubilization in simulated gastric and intestinal fluids, and increased oral bioavailability.

Search for a new gauge boson in electron-nucleus fixed-target scattering by the APEX experiment

We present a search at the Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling α' to electrons. Such a particle A' can be produced in electron-nucleus fixed-target scattering and then decay to an e + e- pair, producing a narrow resonance in the QED trident spectrum. Using APEX test run data, we searched in the mass range 175-250 MeV, found no evidence for an A'→ e+ e- reaction, and set an upper limit of α'/α ~/= 10(-6). Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and couplings for sub-GeV forces.

Child and parental surveys about pre-hospitalization information provision

BACKGROUND

There is little available information about what children and parents would like to know about a forthcoming hospitalization and what they currently receive.

METHODS

The current study was a survey of 102 children between the ages of 6 and 10 years and their parents recruited either from the Recovery Unit following day surgery or from the wards following overnight admissions at Sydney Children's Hospital, Australia. Information was obtained about each child's experience in hospital, the nature and format of information that they had received prior to the admission, and what information the child/parent thought would be helpful to receive.

RESULTS

Parents recorded a total of 163 questions asked by children prior to their admission. Questions related to timing (e.g. duration of admission, length of procedure), pain, procedural information, anaesthesia, needles, whether parents can be present, activities to do in hospital, seeking explanations ('Why' questions), hospital environment, seeking reassurance and miscellaneous questions. Children who were satisfied with the amount of information they received before coming to hospital subsequently reported that they would be significantly less scared should they need to come back to hospital for a future procedure. A total of 46.7% of children received information about their hospitalization from their parent(s) and a further 12% from a doctor and parent.

CONCLUSIONS

Children were found to have many questions about a forthcoming hospitalization. Parents were found to have a major role as information providers. Further research is needed to assess parental confidence and competence to meet their child's information needs.

Cryptococcus gattii in wildlife of Vancouver Island, British Columbia, Canada

Although Cryptococcus gattii has emerged as an important pathogen of humans and domestic animals on Vancouver Island, Canada since 1999; its distribution in regional wildlife species is largely unknown. Opportunistic sampling methods were employed to obtain nasal swabs for fungal culture from wild mammal species residing within the coastal Douglas fir biogeoclimatic zone on the southeast coast of the island. Samples were collected from 91 animals representing 14 species. Cryptococcus gattii was isolated from the nasal swabs of two eastern gray squirrels (Sciurus carolinensis) trapped in Duncan, British Columbia. The relative proportion of nasal colonization in wild mammal species is consistent with findings in domestic animals, suggesting that animals may be good indicators of environmental organisms.

Sodium bicarbonate treatment and ubiquitin gene expression in acidotic human subjects with chronic renal failure

BACKGROUND

In chronic renal failure, metabolic acidosis is associated with increased whole body protein degradation. In rats this effect of acidosis occurs in skeletal muscle and is associated with increased ubiquitin mRNA expression. This has not been demonstrated in humans.

MATERIALS AND METHODS

Six patients with chronic renal failure and acidosis underwent muscle biopsy before and after 1 month's treatment with sodium bicarbonate. RNA was extracted from the biopsy, and the expression of the genes for ubiquitin and the proteasome component, C2, were measured by Northern blotting.

RESULTS AND CONCLUSIONS

There was no significant difference in the expression of ubiquitin or C2 after bicarbonate treatment. This is contrast with results from animal models of acidosis and some other catabolic conditions in humans. This may reflect the complexity of the ubiquitin-dependent pathway, and it may be that changes in ubiquitin expression are only seen with more severe and/or acute changes in pH.

A model for predicting endotoxin concentrations in metalworking fluid sumps in small machine shops

METHODS

In British Columbia, Canada, nineteen small machine shops which used water-based metalworking fluids (MWF) were examined. One bulk MWF sample was taken from each independent sump (N=140) and tested for endotoxin using the Limulus Amoebocyte Lysate assay. Factors that might influence the MWF sump endotoxin concentration were investigated using mixed effect multiple regression modelling to control for repeated measures within shops.

RESULTS

The geometric mean (GM) endotoxin concentration was 6791 EU/ml. Contamination of MWF with tramp oil, MWF pH, MWF temperature, and MWF type were significant predictors of sump fluid endotoxin concentration (model P=0.0001, ordinary least squares R(2) =0.36). Concentrations of endotoxin in sump fluids were increased by MWF contamination with tramp oils such as hydraulic oils, preservative oils, spindle oils, slidway lubricants, gear lubricants, and greases (model predicted GM=17400 EU/ml vs. 1600 EU/ml without tramp oil). Concentrations were also elevated where pH was lower than 8.5 (predicted GM=10600, vs 3600 EU/ml for pH 8.5 to 9.5), where soluble fluids were used (predicted GM=11800 vs. 2800 EU/ml for synthetic fluids), and where sump fluid temperatures were higher (predicted GM=2600 EU/ml at 11 degrees C vs. 21500 EU/ml at 32 degrees C). The within-shop correlation of sump bulk fluid endotoxin concentrations was 38%.

CONCLUSIONS

Minimizing tramp oil contamination, using synthetic fluids, and monitoring pH and temperature would be valuable tools for controlling endotoxin contamination in MWF sumps. In addition, since there was correlation within-shop, contamination of one sump in a shop may suggest changing the fluids in all.

Neonatal screening for medium-chain acyl-CoA dehydrogenase deficiency

Neonatal screening for medium-chain acyl-CoA dehydrogenase (MCAD) deficiency has not yet been introduced in the UK, primarily because of uncertainty about the natural history of the disorder and concerns about the specificity of the screening test. To obtain data on these issues, we did a retrospective study in which we analysed the concentrations of acylcarnitines in stored neonatal blood spots, and reviewed patients with high octanoylcarnitine concentrations at age 7-9 years. The high morbidity and mortality associated with the disorder, and the specificity of acylcarnitine analysis seen in our study support the introduction of screening for MCAD deficiency.

Carnitine palmitoyl transferase I and the control of myocardial beta-oxidation flux

Carnitine palmitoyltransferase I is assumed to be rate limiting for beta-oxidation in all tissues. However, the concentration of malonyl-CoA in heart and muscle is high and is enough to completely inhibit beta-oxidation if this assumption is correct. In this review, we consider whether: (i) there is a malonyl-CoA-insensitive carnitine palmitoyltransferase I activity; (ii) the measured malonyl-CoA concentration in the heart is physiologically meaningful; and (iii) carnitine palmitoyltransferase I is rate-limiting for beta-oxidation in the heart.

Physician explanations for failing to comply with "best practices"

CONTEXT

Substantial effort has been devoted to improving physician compliance with evidence-based guidelines.

OBJECTIVE

To explore physicians' reasons for not following so-called "best practices" in caring for patients with type 2 diabetes.

DESIGN

Descriptive study of self-assessed compliance with five measures of performance.

PARTICIPANTS

Eighty-five internists who volunteered to participate in a practice-based research network created to improve clinical practice.

DATA COLLECTION

Physicians reviewed their own charts of patients with type 2 diabetes mellitus (1755 patient encounters) to assess compliance and offered open-ended comments concerning their reasons for not complying with "best practices."

RESULTS

The physician volunteers reported not complying with the annual foot examination in 13% of encounters. A similar level of noncompliance was reported for the annual lipid profile (15%) and retinal examination (17%). Among the five measures examined, noncompliance was most common for screening urinalysis (26%) and screening microalbuminuria (46%). The physicians' open-ended comments suggested that physician oversight, patient nonadherence, and systems issues were common reasons for noncompliance. However, noncompliance also resulted from a conscious decision by the physician, as indicated by comments about patient age and comorbid illness or, with nephropathy screening, established renal disease or current therapy with angiotensin-converting enzyme inhibitors.

CONCLUSIONS

Even among a self-selected group of physicians, noncompliance with best practices in diabetes is common. Although physician forgetfulness and external factors are frequently offered as reasons for noncompliance, it may also result from a conscious decision, as physicians may disagree about what constitutes "best practices."

Carnitine palmitoyl transferase I and the control of beta-oxidation in heart mitochondria

Mitochondrial beta-oxidation provides much of the fuel requirements of heart and skeletal muscle despite the malonyl-CoA concentration greatly exceeding the IC(50) of carnitine palmitoyl transferase for malonyl-CoA. To try to explore the relationship between inhibition of carnitine palmitoyl transferase I activity and beta-oxidation flux, we measured the flux control coefficient of carnitine palmitoyl transferase I over beta-oxidation carbon flux in suckling rat heart mitochondria. The flux control coefficient was found to be 0.08 +/- 0.05 and 50% of carnitine palmitoyl transferase I activity could be inhibited before beta-oxidation flux was affected. These observations may help to explain the presence of high rates of beta-oxidation despite the high concentration of malonyl-CoA in rat heart; we hypothesize that although not rate-limiting in vitro, carnitine palmitoyl transferase is rate-limiting in vivo because of the high malonyl-CoA concentration in heart and muscle.

Spatial and temporal distribution of airborne Bacillus thuringiensis var. kurstaki during an aerial spray program for gypsy moth eradication

We measured airborne exposures to the biological insecticide Bacillus thuringiensis var. kurstaki (Btk) during an aerial spray program to eradicate gypsy moths on the west coast of Canada. We aimed to determine whether staying indoors during spraying reduced exposures, to determine the rate of temporal decay of airborne concentrations, and to determine whether drift occurred outside the spray zone. During spraying, the average culturable airborne Btk concentration measured outdoors within the spray zone was 739 colony-forming units (CFU)/m3 of air. Outdoor air concentrations decreased over time, quickly in an initial phase with a half time of 3.3 hr, and then more slowly over the following 9 days, with an overall half-time of about 2.4 days. Inside residences during spraying, average concentrations were initially 2-5 times lower than outdoors, but at 5-6 hr after spraying began, indoor concentrations exceeded those outdoors, with an average of 244 CFU/m3 vs. 77 CFU/m3 outdoors, suggesting that the initial benefits of remaining indoors during spraying may not persist as outside air moves indoors with normal daily activities. There was drift of culturable Btk throughout a 125- to 1,000-meter band outside the spray zone where measurements were made, a consequence of the fine aerosol sizes that remained airborne (count median diameters of 4.3 to 7.2 microm). Btk concentrations outside the spray zone were related to wind speed and direction, but not to distance from the spray zone.

The measurement of volatile constituents in Foray 48B, an insecticide prepared from Bacillus thuringiensis var. kurstaki

Foray 48B, an insecticide prepared from Bacillus thuringiensis var. kurstaki (Btk), has been used for many years to combat infestations of Gypsy moths. Foray 48B also contains a large number of 'inert ingredients' which are not disclosed by the manufacturer. Gypsy moths usually enter the country through marine- and airports in close proximity to urban areas, which consequently need to be sprayed. The population affected often demands more detailed information than what is available including the potential presence of volatile organic agents which could be released during spraying, posing a potential health hazard. Four different methods were investigated using GC/mass spectrometry regarding their ability to capture volatile agents associated with Foray 48B. It was found that solid phase micro-extraction was most efficient in capturing volatile agents from the head-space of Foray 48B. Separate trials using 95:5% ethanol/isopropanol mixture and toluene in an impinger configuration were much less efficient. Standard techniques using activated charcoal tubes in the laboratory setting as well as in a field trial did not capture any compounds. It was concluded that the volatile agents associated with Foray 48B did not appear to constitute a significant health hazard and no one agent was a likely candidate to serve as a tracer for Foray 48B exposure.

Plasma coenzyme Q(10) in children and adolescents undergoing doxorubicin therapy

The objective of this study was to test the hypothesis that doxorubicin treatment for cancer in childhood and adolescence causes a dose-related decrease in the concentration of plasma coenzyme Q(10). The concentration of plasma coenzyme Q(10) was measured before and after administration of doxorubicin in six patients, and before and after chemotherapy in six patients undergoing treatments that did not include doxorubicin. There was a significant increase in the concentration of plasma coenzyme Q(10) in post-treatment samples compared to pre-treatment samples in patients treated with doxorubicin (P=0.008; n=32), whereas there were no significant changes in plasma coenzyme Q(10) concentrations in patients treated with chemotherapy that did not include doxorubicin. (P=0.770; n=30). We hypothesise that the increase in plasma coenzyme Q(10) that was observed in patients undergoing doxorubicin treatment is due to release of coenzyme Q(10) from apoptotic or necrotic cardiac tissue. We conclude that the cardiotoxicity due to doxorubicin therapy does not involve acute myocardial depletion of coenzyme Q(10).

Effect of oral antibiotics on intestinal production of propionic acid

BACKGROUND

Propionic acid derived from colonic bacterial fermentation contributes substantially to overall propionate load in children with disorders of propionate metabolism, and its reduction is important for adequate metabolic control.

AIMS

To evaluate the in vitro and in vivo effects of antibiotic treatment on propionate production by colonic bacteria, and plasma propionate concentrations in a child with propionic acidaemia.

METHODS

In vitro fermentation techniques were used to study the effects of addition of antibiotics (metronidazole, clindamycin, erythromycin, and vancomycin) on net faecal production of short chain fatty acids including propionic acid. Courses of oral antibiotics of 7 days duration were used to assess the in vivo effects on faecal propionate production and metabolic control including plasma propionate concentrations.

RESULTS

Metronidazole produced the largest and most consistent reduction (77-84%) in the production in vitro of propionate from faecal homogenates. Oral administration of metronidazole reduced faecal propionate production by 43% within 24 hours of treatment; a 7 day course virtually eliminated it for the next 3 weeks. These reductions were accompanied by substantially lowered plasma propionate concentrations during the same period.

CONCLUSIONS

Intermittent courses of oral metronidazole might be as effective as continuous treatment in reducing gut propionate production in children with disorders of propionate metabolism.

The mitochondrial trifunctional protein: centre of a beta-oxidation metabolon?

The trifunctional enzyme comprises three consecutive steps in the mitochondrial beta-oxidation of long-chain acyl-CoA esters: 2-enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase and 3-ketoacyl-CoA thiolase. Deficiencies in either 3-hydroxyacyl-CoA dehydrogenase activity, or all three activities, are important causes of human disease. The dehydrogenase and thiolase have a requirement for NAD+ and CoA respectively, whose levels are conserved within the mitochondrion and thus provide possible means for control and regulation of beta-oxidation. Using analysis of the intact CoA ester intermediates produced by the complex, we have examined the sensitivity of the complex to NAD+/NADH and acetyl-CoA. We consider the evidence for channelling within the trifunctional protein and propose a model for a beta-oxidation 'metabolon'.

Preliminary report on the results of the second phase of a round- robin endotoxin assay study using cotton dust

In an on-going endotoxin assay study, a two-part interlaboratory endotoxin assay study has been completed. The purpose of the study was to compare the variation in assay results between different laboratories, and, if the variation was high, to see if a common protocol would reduce the variation. In both parts of the study, membrane filters laden with the same approximate amount and type of cotton dust were sent for analysis to laboratories that "routinely" perform endotoxin analyses. First, each of these laboratories performed the analysis using the methodology common to its laboratory. In the second part of the study, membrane filters with cotton dust were again sent to the same laboratories where the analyses were performed as before but with a common extraction protocol. The preliminary results from the first phase of the study have been collected and showed that intra-laboratory variations were small, but large and significant interlaboratory variation was observed. The results were reported elsewhere. The preliminary results from the second part of the study consisting of the data currently collected are presented here. Again, intra-laboratory variations were small, but, also again, large and significant inter-laboratory variation was observed. However, in this part of the study, the range between the highest and lowest average results was narrower than in the first part of the study. Influence of the assay kit type was examined. The variation within assay kit type was small but significant differences in results were observed between assay kit types. The findings suggest that endotoxin concentration in samples can be ranked within laboratories, but not necessarily between laboratories. However, some of the variation between laboratories has been reduced by a common extraction protocol which suggests the possibility of further standardization that may lead to better comparability between laboratories.

Wheat antigen content of inhalable dust in bakeries: modeling and an inter-study comparison

The purposes of this study were (a) to compare wheat antigen content of inhalable bakery dust in Canada and the Netherlands and, (b) to evaluate the validity of dust exposure measurement as a surrogate of specific antigen exposure. Wheat antigen exposure data from the studies of Canadian and Dutch bakeries were used to explore the correlation between dust and antigen levels, and identify factors explaining variability of the antigen content of bakery dust. Direct comparison and pooling of the data were possible because the same antigen assay was used in both studies. Wheat antigen exposure samples totaling 544 were available, all originating from personal full-shift monitoring of bakery workers. The wheat antigen content of bakery dust varied greatly between the two studies and with different products within each study. Bakery dust from the Canadian study had a much higher wheat antigen content. Therefore, the interstudy difference in the wheat antigen content of bakery dust was by far the most significant in undermining the validity of the use of dust levels as a surrogate measures of wheat antigen exposure. The production of croissants, wheat bread and buns, puff pastry, bagels, and cinnamon buns was associated with increased wheat antigen content of bakery dust, while in rye bread production, bakery dust with less wheat antigen content was emitted. Although we can, in part, account for the pattern of variability in the wheat antigen content of bakery dust (explaining 49% of it), we concluded that the effort involved in modeling it accurately would probably exceed that expended in direct measurement of the antigen level. Therefore, for the exposure assessments carried out for the purpose of managing occupational risks of aeroallergen exposure in bakeries, we recommend the use of analytical techniques that can directly measure antigen exposure.

Tandem mass spectrometry--the potential

We summarize the current status of the use of tandem mass spectrometry for the detection of inherited metabolic disorders and the investigation of the pathophysiology of these conditions. We also indicate some of the more recent developments of this technology that have potential diagnostic applications.

Intermediates of myocardial mitochondrial beta-oxidation: possible channelling of NADH and of CoA esters

Adult rat heart mitochondria were isolated and incubated with [U-14C]hexadecanoyl-CoA or unlabelled hexadecanoyl-CoA. The accumulating CoA and carnitine esters and [NAD+]/[NADH] ratio were measured by HPLC or tandem mass spectrometry. Despite minimal changes in the intramitochondrial [NAD+]/[NADH] ratio, 2, 3-unsaturated and 3-hydroxyacyl esters were observed as well as saturated acyl-CoA and acylcarnitine esters. In addition to acetylcarnitine, significant amounts of butyryl-, hexanoyl-, octanoyl- and decanoylcarnitines were detected and measured. Rat myocardial beta-oxidation is subject to control at the level of 3-hydroxyacyl-CoA dehydrogenase but this control is not due to a simple lack of oxidised NAD. We hypothesise a pool of NAD in contact between the trifunctional protein of beta-oxidation and complex I of the respiratory chain, the turnover of which is responsible for some of the control of beta-oxidation flux. In addition, short- and medium-chain acylcarnitine esters were detected whereas only small amounts of long-chain acylcarnitines were present. This may imply the presence of a mitochondrial carnitine octanoyl transferase or may reflect channelling of long-chain CoA esters so that they are not available for carnitine palmitoyl transferase II activity.

Clear correlation of genotype with disease phenotype in very-long-chain acyl-CoA dehydrogenase deficiency

Very-long-chain acyl-CoA dehydrogenase (VLCAD) catalyzes the initial rate-limiting step in mitochondrial fatty acid beta-oxidation. VLCAD deficiency is clinically heterogenous, with three major phenotypes: a severe childhood form, with early onset, high mortality, and high incidence of cardiomyopathy; a milder childhood form, with later onset, usually with hypoketotic hypoglycemia as the main presenting feature, low mortality, and rare cardiomyopathy; and an adult form, with isolated skeletal muscle involvement, rhabdomyolysis, and myoglobinuria, usually triggered by exercise or fasting. To examine whether these different phenotypes are due to differences in the VLCAD genotype, we investigated 58 different mutations in 55 unrelated patients representing all known clinical phenotypes and correlated the mutation type with the clinical phenotype. Our results show a clear relationship between the nature of the mutation and the severity of disease. Patients with the severe childhood phenotype have mutations that result in no residual enzyme activity, whereas patients with the milder childhood and adult phenotypes have mutations that may result in residual enzyme activity. This clear genotype-phenotype relationship is in sharp contrast to what has been observed in medium-chain acyl-CoA dehydrogenase deficiency, in which no correlation between genotype and phenotype can be established.

Endotoxin exposure among softwood lumber mill workers in the Canadian province of British Columbia

An increased prevalence of respiratory problems among softwood lumber mill workers has been observed in a number of studies. These workers are potentially exposed to a variety of respiratory hazards including wood dust, abietic or other resin acids, monoterpenes, and fungi, as well as endotoxins. The objectives of this study were to determine if lumber mill workers were exposed to hazardous levels of airborne endotoxin and to identify the factors contributing to high exposures. Personal endotoxin samples (n = 216) were collected in four lumber mills in the Canadian province of British Columbia. The mean personal exposure concentration was 2.09 ng/m.(3) and 9% of the samples were above 5 ng/m.(3). Factors related to the personal endotoxin exposure were type of job, use of compressed air, the percentage of time spent in a booth or cab during a shift, and dust concentration. Log storage practices were also suspected of playing a role. The levels of exposure observed in this study were low compared to the levels reported for populations with respiratory problems attributed to endotoxins.

Control of mitochondrial beta-oxidation: sensitivity of the trifunctional protein to [NAD+]/[NADH] and [acetyl-CoA]/[CoA]

Isolated human mitochondrial trifunctional protein was incubated with 2-hexadecenoyl-CoA, CoA and NAD+ and the resultant CoA esters measured. Steady state with respect to the concentrations of the intermediates 3-hydroxyhexadecanoyl-CoA and 3-ketohexadecanoyl-CoA and the rate of formation of the product tetradecanoyl-CoA was reached within 4 min. Flux was greatly enhanced by the addition of Tween 20 (0.2% v/v) which stimulated 3-ketoacyl-CoA thiolase activity by over 7-fold. When 3-ketoacyl-CoA thiolase was not stimulated, 3-hydroxyhexadecanoyl-CoA was the prominent CoA ester accumulated, presumably due to inhibition of 3-hydroxyacyl-CoA dehydrogenase activity by accumulated 3-ketoacyl-CoA, analogous to the inhibition of short-chain 3-hydroxyacyl-CoA dehydrogenase by 3-ketoacyl-CoA. When [NAD+]/[NADH] was varied at a fixed total [NAD++NADH], the overall flux was only inhibited by [NAD+]/[NADH] less than 1. In contrast, when [acetyl-CoA]/[CoA] was varied at a fixed total [CoA], much greater sensitivity was observed.

Smith-Lemli-Opitz syndrome: a variable clinical and biochemical phenotype

We have reviewed all known UK cases of Smith-Lemli-Opitz syndrome. Among 49 cases with proven 7-dehydrocholesterol reductase deficiency, half had been terminated or had died in infancy. The minimum incidence is 1 in 60,000. The frequent occurrence of hypospadias may account for 71% of recognised cases being male. Important common features which emerged include short thumbs, severe photosensitivity, aggressive behaviour, and atrioventricular septal defect. The typical facial appearance becomes less obvious with age and 20% of cases did not have 2/3 toe syndactyly. Biochemical measurements of serum 7-dehydrocholesterol did not correlate with clinical severity.

Determinants of wheat antigen and fungal alpha-amylase exposure in bakeries

The study's objectives were to measure flour antigen exposure in bakeries and define the determinants of exposure. Ninety-six bakery workers, employed in seven different bakeries, participated in the study. Two side-by-side full-shift inhalable dust samples were obtained from each study participant on a single occasion. The flour antigen exposure was measured as wheat antigen and fungal alpha-amylase content of the water-soluble fraction of inhalable dust, assayed via enzyme-linked immunosorbent assays. During the entire sampling period bakers were observed and information on 14 different tasks was recorded at 15-minute intervals. Other production characteristics were also recorded for each sampling day and used in statistical modeling to identify significant predictors of exposure. The mean alpha-amylase antigen exposure was 22.0 ng/m3 (ranging from below the limit of detection of 0.1 ng/m3 to 307.1 ng/m3) and the mean wheat antigen exposure was 109 micrograms/m3 (ranging from below the limit of detection of 1 microgram/m3 to 1018 micrograms/m3). Regression models that explained 74% of variability in wheat antigen and alpha-amylase antigen exposures were constructed. The models indicated that tasks such as weighing, pouring, and operating dough-brakers increased flour antigen exposure, while packing and decorating resulted in lower exposures. Croissant, puff-pastry, and bread/bun production lines were associated with increased exposure, while cake production and substitution of dusting with the use of divider oil were associated with decreased exposure. Exposure levels can be reduced by the automation of forming tasks, alteration of tasks requiring pouring of flour, and changes to the types of products manufactured.

Integrated telematic support for paediatrics: a practical model

This paper describes the benefits gained and the organizational and practical considerations involved in establishing a relatively low-cost telematic support network for paediatric care and research. It is based on a case study in north-east England, where such a system has been implemented, supporting multimedia conferencing and reference facilities, postgraduate education and management information. The role of this type of service in regional health-care provision is discussed, for paediatrics and other disciplines.

Changes in protein turnover, IGF-I and IGF binding proteins in children with cancer

Changes in insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding proteins (IGFBPs) were correlated with protein synthesis and breakdown using [1-13C]leucine before chemotherapy and during subsequent febrile neutropenia (FN) in eight children with cancer, aged 6.3-17.5 y. IGF-I levels were similar to age-matched controls before chemotherapy (mean +/- SEM: 250+/-28 and 228+/-22 microg l(-1), respectively). During FN, IGF-I fell to 156+/-22 microg l(-1) (p = 0.02), and rose to 276+/-27 microg l(-1) with recovery at 6 months (p = 0.004). Similarly, IGFBP-3 decreased from 4.0+/-0.2 mg l(-1) before chemotherapy to 3.0+/-0.3 mg l(-1) during FN (p = 0.01), and returned to 4.1+/-0.2 mg l(-1) at 6 months (p = 0.01). IGF-I correlated with IGFBP-3 (r = +0.7, p < 0.001). Scanning densitometry showed a decrease in IGFBP-3 from 94 to 54% during FN, when the presence of IGFBP-3 protease activity was observed. Compared with normal human serum, IGFBP-2 was elevated throughout the study. IGFBP-1 increased from 14.6+/-3.5 to 30.6+/-2.8 microg l(-1) (p = 0.004), whereas serum insulin decreased from 26.5+/-6.8 to 7.8+/-0.8 mU l(-1) (p = 0.03) before and during FN, respectively. Whilst IGF-I and IGFBP-3 fell, daytime growth hormone increased from 3.3+/-0.6 to 6.7+/-0.8 mU l(-1) (p=0.01), and cortisol from 197+/-48 to 594+/-98 nmol l(-1) (p = 0.005). Albumin decreased from 47+/-2 to 38+/-2 g l(-1) (p = 0.004) and improved to 47+/-2 g l(-1) with recovery (p = 0.003). Protein synthesis increased from 4.5+/-0.4 to 5.0+/-0.6 g kg(-1)d(-1) before chemotherapy and during FN, while protein breakdown rose from 5.4+/-0.4 to 6.3+/-0.4 kg(-1)d(-1). Increasing protein breakdown was related to falling IGF-I and IGFBP-3 levels. Modification of IGFBP-3 by circulating proteolytic activity may alter IGF bioavailability, allowing protein synthesis to increase during periods of severe catabolic stress.

Thiamine deficiency mimicking acute rejection following cardiac transplantation

We describe a recipient of an orthotopic cardiac transplant who developed severe ventricular dysfunction following an episode of sepsis. He had normal cardiac biopsies and responded to treatment with thiamine. Causes other than rejection should be considered in patients who have received a cardiac transplant and who present in cardiac failure.