Alloreactivity and autoreactivity converge to support B cell epitope targeting in transplant rejection

Antibody (Ab) responses against human leukocyte antigen (HLA) proteins mismatched between donor and recipient are leading cause of allograft loss in kidney transplantation. However, therapies targeting alloreactive B cell and Ab-secreting cell (ASC) are lacking, motivating the need to understand how to prevent and abrogate these alloresponses. Using molecular, structural, and proteomic techniques, we profiled the B cell response in a kidney transplant recipient with antibody-mediated rejection and graft loss. We found that this response spanned the rejected organ and peripheral blood, stimulated the differentiation of multiple B cell subsets, and produced a high-affinity, donor-specific, anti-HLA response. We found epitopic immunodominance that relied on highly exposed, solvent-accessible mismatched HLA residues as well as structural and biomolecular evidence of autoreactivity against the recipient's self-HLA allele. These alloreactive and autoreactive signatures converged in the recipient's circulating donor-specific Ab repertoire, suggesting that rejection requires both the recognition of non-self and breaches of tolerance to lead to alloinjury and graft loss.

Expedient Endovascular Hemorrhage Control During Anterior Lumbar Spinal Exposure Allows Procedural Completion in Rescued Patients

OBJECTIVES

To propose a contemporary management strategy for venous injury during anterior lumbar spinal exposure that incorporates endovascular treatment.

METHODS

Vein injuries suffered by patients treated in a single practice were reviewed. A treatment algorithm based on these experiences was formulated.

RESULTS

Between 2015 and 2018, 914 patients received anterior access procedures for indicated lumbar interbody fusions. Of these patients, 15 (1.6%) suffered minor vascular injuries treated with manual pressure or suture repair. Four (0.4%) patients undergoing anterior lumbar spine surgery suffered major venous injuries, all of whom received the indicated spinal hardware following endovascular rescue. Primary repair was attempted in three patients before endovascular control and not at all in one. Vascular access was obtained via the bilateral femoral veins in 2 patients, unilateral femoral in one, and bilateral femoral plus right internal jugular vein in one. Stent choice included both uncovered (5, 63%) and covered stents (3, 38%). Deep venous thrombosis occurred in 2 patient's post-treatment. 1 DVT was encountered in the setting of a covered stent and 1 uncovered stent thrombosis was treated with catheter-directed lysis 4 weeks post-operatively. Ultimately, 3 patients were therapeutically anticoagulated. Mean follow-up is 13 months (range 1-36) with duplex ultrasounds available at 6 months or later in 3 of 4 patients. There is no evidence of post-thrombotic syndrome in the 2 patients that developed DVT's or in-stent stenosis in the 3 patients with available follow-up imaging.

CONCLUSIONS

Endovascular techniques are important adjuncts when controlling large-volume hemorrhage associated with venous tears during anterior spinal exposure. Adequate direct compression allowing occlusion balloon inflation are key steps to reduce blood loss. Covered and uncovered stents are both appropriate choices to treat injuries. Patients must be anticoagulated post-operatively and surveilled for the sequelae of venous insufficiency. With expedient hemostasis, the indicated spinal surgery may be safely completed.

The effect of inflammation on serum zinc concentrations and the prevalence estimates of population-level zinc status among Congolese children aged 6-59 months

BACKGROUND/OBJECTIVES

Zinc is a negative acute-phase reactant; hence, its concentration decreases in the presence of inflammation. There is no current consensus on how to control for the effect of inflammation on serum zinc, which has implications for accurate estimates of population-level zinc status. We aimed to measure the association between inflammation and serum zinc concentrations and to compare the means and the prevalence of zinc deficiency using unadjusted and inflammation-adjusted serum zinc concentrations among Congolese children.

SUBJECTS/METHODS

Non-fasting blood was collected in the afternoon in trace element-free vacutainers from 744 apparently healthy children aged 6-59 months in the Democratic Republic of the Congo. Serum was analyzed for zinc, C-reactive protein (CRP) and α-1 acid glycoprotein (AGP) for 665 children with complete data for all three biomarkers. Linear regression was used to generate correction factors (CFs) based on three stages of inflammation: incubation (CRP >5 mg/l and normal AGP), early convalescence (CRP >5 mg/l and AGP >1 g/l) and late convalescence (AGP >1 g/l and normal CRP), relative to no inflammation.

RESULTS

Overall unadjusted mean±s.d. serum zinc concentration was 9.4±2.1 μmol/l. Study-generated CFs (95% confidence interval) for incubation, early and late convalescence were 1.01 (0.88, 1.14), 1.15 (1.11, 1.21) and 1.07 (1.03, 1.11), respectively. After applying the CFs, overall adjusted mean±s.d. serum zinc concentration was 10.1±2.2 μmol/l, and prevalence of zinc deficiency (<8.7 μmol/l) decreased from 35% (n=234/665) to 24% (n=160/665).

CONCLUSIONS

Adjustment of zinc concentrations for inflammation is warranted when assessing population-level zinc status.European Journal of Clinical Nutrition advance online publication, 23 August 2017; doi:10.1038/ejcn.2017.127.

Acute pancreatitis after transarterial chemoembolization of hepatocellular carcinoma with drug-eluting beads

Nontarget embolization is a relatively common cause of post-chemoembolization complications. Clinical presentation following nontarget embolization varies from minimal to fatal, and oftentimes relates to the vascular distribution embolized rather than the amount or type of embolic agent. Post-chemoembolization pancreatitis is an uncommon complication, but one that is known to occur. The following manuscript presents a case of post-chemoembolization pancreatitis, and suggests methods to decrease this complication as well as treatment once the complication occurs.

Household food insecurity and dietary diversity as correlates of maternal and child undernutrition in rural Cambodia

OBJECTIVES

To assess household food insecurity and dietary diversity as correlates of maternal and child anthropometric status and anemia in rural Cambodia.

METHODS

Trained interviewers administered a survey to 900 households in four rural districts of Prey Veng, Cambodia. The Household Food Insecurity Access Scale (HFIAS) and Household Dietary Diversity Score (HDDS) were used to assess household food insecurity and dietary diversity. The height, weight and hemoglobin concentration of the mother and youngest child under 5 years in each household were measured. Multivariate logistic regression models were constructed to assess the association between household food insecurity and dietary diversity, and child stunting and wasting, maternal thinness, maternal and child anemia.

RESULTS

The mean (s.d.) HFIAS and HDDS scores were 5.3 (3.9) and 4.7 (1.6), respectively. The respective prevalences of mild, moderate and severe food insecurity were 33, 37 and 12%. Maternal thinness, child stunting and child wasting were present in 14.6, 25.4 and 8.1% of respondents, respectively. The risk of maternal thinness, but not child stunting or wasting, increased as the severity of household food insecurity increased. Household food insecurity was also positively associated with maternal, but not child, anemia. Household dietary diversity status was not significantly associated with any of the outcomes we assessed.

CONCLUSIONS

Efforts to improve household food security are important as a means of promoting maternal nutritional status; however, additional research is needed to better understand the role of other factors that are driving the burden of child undernutrition in Cambodia.

Downstaging disease in patients with hepatocellular carcinoma outside of Milan criteria: strategies using drug-eluting bead chemoembolization

PURPOSE

To assess downstaging rates in patients with United Network for Organ Sharing stage T3N0M0 hepatocellular carcinoma (HCC) treated with doxorubicin-eluting bead transarterial chemoembolization to meet Milan criteria for transplantation.

MATERIALS AND METHODS

A single-center retrospective review of 239 patients treated with doxorubicin-eluting bead (DEB) chemoembolization between September 2008 and December 2011 was undertaken. Baseline and follow-up computed tomography or magnetic resonance imaging was assessed for response based on the longest enhancing axial dimension of each tumor (ie, modified Response Evaluation Criteria In Solid Tumors measurements), and medical records were reviewed. Fisher exact tests and exact logistic regression were used to test the association of patient and disease characteristics with downstaging.

RESULTS

After exclusions, 22 patients remained in the analysis, 17 of whom (77%) had their HCC downstaged to meet Milan criteria. Among those whose disease was downstaged, seven underwent transplantation, one remained listed for transplantation, six had disease progression beyond Milan criteria, two underwent conventional transarterial chemoembolization, and one underwent radiofrequency ablation. The seven patients who received transplants were still living, but recurrent HCC developed in two. Baseline age (P = .25), Model for End-stage Liver Disease score (P = .77), and α-fetoprotein (AFP) level (P = 1.00) were similar between patients with and without downstaged HCC. No associations were observed between the odds of downstaging and sex (P = .21), Child-Pugh class (P = .14), Child-Pugh class controlling for baseline tumor multiplicity (P = .15), Eastern Cooperative Oncology Group performance status (P = 1.00), tumor burden (P = .31), multiple tumors (P = .31), or hepatitis C virus infection (P = 1.00). Fifteen patients who did not receive transplants were alive at 1 year, with two progression-free. Baseline AFP levels differed between those who survived 1 year and those who did not (P = .02), but did not differ by progression-free survival status (P = .62).

CONCLUSIONS

T3N0M0 HCC treatment with DEB chemoembolization has a high likelihood (77%) of downstaging the disease to meet Milan criteria.

Upper and lower airways associations in patients with chronic rhinosinusitis and bronchiectasis

BACKGROUND

Bronchiectasis is an uncommon disease of the lower airways characterized by bronchial wall destruction and permanent bronchiolar dilation. Several etiologic categories exist, and patients with bronchiectasis often complain of symptoms suggestive of chronic rhinosinusitis (CRS). The present study investigates the association between bronchiectasis and CRS using radiologic and bacteriologic data.

METHODS

Retrospective chart review from a tertiary care respiratory hospital was performed. Sinus computed tomography (CT) scans were examined for extent of disease and relationship to pulmonary disease severity. Statistical analysis was performed with Student t test and linear regression. Upper and lower airway cultures from patients with both bronchiectasis and CRS were compared using the chance adjusted agreement.

RESULTS

Patients with bronchiectasis were found to have a significantly higher Lund-Mackay score when compared to patients with allergic rhinitis (p = 0.047). Lund-Mackay CT score did not correlate with forced expiratory volume in 1 second (FEV1 ) and FEV1 :forced vital capacity (FVC), or presence of Pseudomonas aeruginosa. Correlation of upper and lower airway bacterial cultures in patients with both bronchiectasis and CRS was noted (kappa = 0.294, p = 0.004), particularly when P. aeruginosa was present (kappa = 0.49, p < 0.0001).

CONCLUSION

The current study suggests that the upper and lower airways may be linked in CRS and bronchiectasis from both an objective radiologic standpoint and a bacteriologic perspective. This finding carries implications for disease pathogenesis, clinical care, and future research.

Effect of PGX, a novel functional fibre supplement, on subjective ratings of appetite in overweight and obese women consuming a 3-day structured, low-calorie diet

Introduction:

Dietary factors that help control perceived hunger might improve adherence to calorie-reduced diets.

Objectives:

The objective of the study was to investigate the effect of supplementing a three-day, low-calorie diet with PolyGlycopleX (PGX), a highly viscous fibre, on subjective ratings of appetite compared with a placebo.

Methods:

In a double-blind crossover design with a 3-week washout, 45 women (aged 38±9 years, body mass index 29.9±2.8 kg m⁻²) were randomised to consume a 1000-kcal per day diet for 3 days, supplemented with 5 g of PGX or placebo at each of breakfast, lunch and dinner. Subjective appetite was assessed using 100 mm visual analogue scales that were completed daily before, between and after consumption of meals.

Results:

Thirty-five women completed the study. Consumption of PGX compared with placebo led to significantly lower mean area under the curve for hunger on day 3 (440.4 versus 375.4; P=0.048), prospective consumption on day 3 (471.0 versus 401.8; P=0.017) and the overall 3-day average (468.6 versus 420.2; P=0.026). More specifically, on day 3 PGX significantly reduced total appetite, hunger, desire to eat and prospective consumption for 2.5 and 4.5 h after lunch and before dinner times, with hunger also being reduced 2.5 h after dinner (P<0.05).

Conclusion:

The results show that adding 5 g of PGX to meals during consumption of a low-calorie diet reduces subjective ratings of prospective consumption and increases the feelings of satiety, especially during afternoon and evening. This highly viscous polysaccharide may be a useful adjunct to weight-loss interventions involving significant caloric reductions.

Bacterial diversity of the digestive gland of Sydney rock oysters, Saccostrea glomerata infected with the paramyxean parasite, Marteilia sydneyi

AIMS

To determine whether the infestation by the protozoan paramyxean parasite, Marteilia sydneyi, changes the bacterial community of the digestive gland of Sydney rock oysters, Saccostrea glomerata.

METHODS AND RESULTS

Six 16S rDNA clone libraries were established from three M. sydneyi-infected and three un-infected oysters. Restriction enzyme analysis followed by sequencing representative clones revealed a total of 23 different operational taxonomic units (OTUs) in un-infected oysters, comprising the major phyla: Firmicutes, Proteobacteria, Cyanobacteria and Spirocheates, where the clone distribution was 44, 36, 7 and 5%, respectively. Close to half of the OTUs are not closely related to any other hitherto determined sequence. In contrast, S. glomerata infected by M. sydneyi had only one OTU present in the digestive gland. Phylogenetic analysis of the 16S rDNA sequence reveals that this dominant OTU, belonging to the alpha-Proteobacteria, is closely related to a Rickettsiales-like prokaryote (RLP).

CONCLUSIONS

The microbiota of the digestive gland of Sydney rock oysters is changed by infection by M. sydneyi, becoming dominated by a RLP, and generally less diverse. The bacterial community of un-infected S. glomerata differs from previous studies in that we identified the dominant taxa as Firmicutes and alpha-Proteobacteria, rather than heterotrophic gamma-Proteobacteria.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first culture-independent study of the microbiota of the digestive glands of edible oysters to the species level. The commercial viability of the Sydney rock oyster industry in Australia is currently threatened by Queensland Unknown disease and the changes in the bacterial community of S. glomerata corresponding with infection by M. sydneyi sheds further light on the link between parasite infection and mortality in this economically damaging disease.

Sensitivity of papilledema as a sign of shunt failure in children

PURPOSE

Papilledema is considered one of the cardinal ophthalmologic signs of shunt failure. However, the prevalence of papilledema in children with shunt malfunction has not been systematically investigated. The purpose of this study is to determine the sensitivity of papilledema as a sign of shunt failure in children.

METHODS

A prospective evaluation was undertaken of all children (n = 29; <19 years of age) with surgically confirmed shunt malfunction who were treated at Arkansas Children's Hospital between July 2007 and April 2008. Each child had a dilated fundus examination and/or RetCam photograph while under anesthesia immediately before shunt repair. The optic disk was evaluated for the presence of papilledema and pallor. Intracranial pressure was measured during surgical shunt repair at the discretion of the neurosurgeon.

RESULTS

Twenty-nine patients had surgically confirmed shunt failure. Patient's age ranged from 36 days to 18 years, 8 months. Four patients (14%) had papilledema, and 1 patient had severe optic disk pallor. The remaining 24 patients had flat optic disks. Five patients had flat optic disks despite an intracranial pressure >/=300 mm H(2)O.

CONCLUSIONS

Papilledema is not a sensitive sign of shunt failure. Even children with severe elevations in intracranial pressure from shunt malfunction may have flat optic disks. Therefore, physicians that evaluate children with shunts should be aware that a normal optic disk does not preclude shunt malfunction.

Association between quantitative measures of skin color and plasma 25-hydroxyvitamin D

We examined the relationship between vitamin D and skin color measured by reflectance colorimetry at an exposed and un-exposed site in 321 people. Exposed but not unexposed skin color was associated with better vitamin D status. Sun-exposure was more important than natural skin color in determining vitamin D status in our population.

INTRODUCTION

Vitamin D is obtained through UV synthesis in the skin where melanin limits its synthesis. Ethnicity is often used as a proxy for skin color, but skin color varies considerably. The relation between quantitative measures of skin color and plasma 25-hydroxyvitamin D (25OHD) concentration has not been well described.

METHODS

The aim of this study was to determine the association between constitutive (natural) and sun-induced skin color and 25OHD in a group of Pacific People (n = 87) and Europeans (n = 255) living in NZ (46 degrees S) in summer. Plasma 25OHD was determined and sun-induced (outer fore-arm) and constitutive (upper inner-arm) measured by reflectance colorimetry.

RESULTS

Mean (SD) 25OHD was significantly higher in Europeans than Pacific People, 88 (31) nmol/L vs. 75 (34) nmol/L, respectively. Based on constitutive skin color, 35% of participants were very light, 45% light, 16% intermediate, 4% tanned, and 0% brown or dark. Skin color at the forearm but not constitutive skin color was a significant predictor of 25OHD. Each 10 degrees lower skin color value at the forearm (more tanning) was associated with a 5 nmol/L higher 25OHD (P < 0.001).

CONCLUSIONS

Tanning but not natural skin color was an important determinant of 25OHD. Further study is needed in a population with a higher proportion of darker skin people.

Vitamin D status and its association with parathyroid hormone concentrations in women of child-bearing age living in Jakarta and Kuala Lumpur

OBJECTIVE

To describe the vitamin D status of women living in two Asian cities,--Jakarta (6 degrees S) and Kuala-Lumpur (2 degrees N), to examine the association between plasma 25-hydroxyvitamin D and parathyroid hormone (PTH) concentrations, and to determine a threshold for plasma 25-hydroxyvitamin D above which there is no further suppression of PTH. Also, to determine whether dietary calcium intake influences the relationship between PTH and 25-hydroxyvitamin D.

DESIGN

Cross-sectional.

SETTING

Jakarta, Indonesia and Kuala Lumpur, Malaysia.

PARTICIPANTS

A convenience sample of 504 non-pregnant women 18-40 years.

MAIN MEASURES

Plasma 25-hydroxyvitamin D and PTH.

RESULTS

The mean 25-hydroxyvitamin D concentration was 48 nmol/l. Less than 1% of women had a 25-hydroxyvitamin D concentration indicative of vitamin D deficiency (<17.5 nmol/l); whereas, over 60% of women had a 25-hydroxyvitamin D concentration indicative of insufficiency (<50 nmol/l). We estimate that 52 nmol/l was the threshold concentration for plasma 25-hydroxyvitamin D above which no further suppression of PTH occurred. Below and above this concentration the slopes of the regression lines were -0.18 (different from 0; P=0.003) and -0.01 (P=0.775), respectively. The relation between vitamin D status and parathyroid hormone concentration did not differ between women with low, medium or high calcium intakes (P=0.611); however, even in the highest tertile of calcium intake, mean calcium intake was only 657 mg/d.

CONCLUSION

On the basis of maximal suppression of PTH we estimate an optimal 25-hydroxyvitamin D concentration of approximately 50 nmol/l. Many women had a 25-hydroxyvitamin D below this concentration and may benefit from improved vitamin D status.

A comparison of the effects of A1 and A2 β-casein protein variants on blood cholesterol concentrations in New Zealand adults

Beta-casein is a cow's milk protein that occurs predominantly in two forms, A1 and A2. Epidemiological evidence suggests that per capita consumption of beta-casein A1 is associated with national mortality rates from ischaemic heart disease. A biological mechanism was proposed after rabbits fed diets containing beta-casein A2 had lower serum cholesterol concentrations and less aortic intimal thickening than rabbits fed beta-casein A1. We tested whether beta-casein A1 and A2 variants differentially affect plasma cholesterol concentrations in humans. In a randomised crossover trial of two four-and-a-half week periods without washout, 62 participants replaced all dairy products in their diet with 500 mL of low-fat milk and 28 g of full-fat cheese that differed in the proportion of beta-casein A1 and A2 variants. Duplicate blood samples were taken on non-consecutive days at the end of each treatment period from 55 people who completed the study. Mean (S.D.) plasma total, low-density and high-density lipoprotein cholesterol concentrations were 5.60 (0.77), 3.73 (0.70) and 1.26 (0.34) mmol/L after the A1 diet and 5.63 (0.81), 3.75 (0.75) and 1.27 (0.37) mmol/L after the A2 diets. We found no evidence that dairy products containing beta-casein A1 or A2 exerted differential effects (P > 0.05) on plasma cholesterol concentrations in humans.

Serum 25-hydroxyvitamin D concentrations of New Zealanders aged 15 years and older

INTRODUCTION

Vitamin D plays an important role in bone health. Our purpose was to measure serum 25-hydroxyvitamin D concentrations and their determinants in a national sample (n=2,946) of New Zealanders aged 15 years and over.

FINDINGS

Mean (99% CI) serum 25-hydroxyvitamin D concentrations were 47 (45-50) nmol/l in women and 52 (49-55) nmol/l in men. Mean concentrations in New Zealand European and Others (NZEO, n=2,440), Māori (n=370), and Pacific (n=136) were 51 (49-53), 42 (38-46) and 37 (33-42) nmol/l, respectively. Three percent of New Zealanders had serum 25-hydroxyvitamin D concentrations indicative of deficiency (<or=17.5 nmol/l); 48% and 84% were insufficient based on cutoffs of <or=50 and <or=80 nmol/l. Determinants of serum 25-hydroxyvitamin D concentrations in women were age, ethnicity, obesity, latitude and season; determinants in men were ethnicity and season. Serum 25-hydroxyvitamin D in women declined with age; mean concentration was 13 (8-18) nmol/l lower in women 65 years or older and 9 (5-13) nmol/l lower in women 45-64 years compared with women 15-18 years. Spring to summer differences in serum 25-hydroxyvitamin D were 31 (28-34) and 28 (25-31) nmol/l in women and men, respectively. Obese women had lower vitamin status than normal-weight women by 6 (3-10). Women living in the South Island had a mean serum 25-hydroxyvitamin D that was 6 (3-9) nmol/l lower than women living in the North Island. Ethnicity and season are the major determinants of serum 25-hydroxyvitamin D in New Zealanders.

CONCLUSION

The high prevalence of vitamin D insufficiency in New Zealanders, particularly in older women, may warrant strategies to improve vitamin D status.

Serum vitamin B12 concentrations and atrophic gastritis in older New Zealanders

OBJECTIVE

To determine the serum vitamin B(12) status of older New Zealanders and to assess the impact of atrophic gastritis on vitamin B(12) status.

DESIGN

A cross-sectional nationally representative population-based survey.

METHOD

Serum vitamin B(12) concentrations were used to assess vitamin B(12) status. The presence and severity of atrophic gastritis was classified using serum pepsinogen I and II.

SUBJECTS

A total of 466 noninstitutionalized urban and rural dwelling New Zealanders aged 65 y or older who participated in the 1997 National Nutrition Survey.

RESULTS

The prevalence of deficient (<148 pmol/l) and marginal (148-221 pmol/l) serum vitamin B(12) concentrations was 12 and 28%, respectively. The prevalence of atrophic gastritis was 6.7% (severe 3.1%, mild-moderate 3.6%). While atrophic gastritis increased the relative risk (RR, 95% CI) of having a deficient or marginal serum vitamin B(12) concentration by 21-fold (6-67) and five-fold (1-17), respectively, those who had atrophic gastritis made up only 33 and 6% of the participants with deficient or marginal serum vitamin B(12) concentrations. An intake of vitamin B(12) from food that exceeded the recommended dietary allowance (2.4 mug/day) did not protect against deficient (RR 0.5; 95% CI: 0.2, 1.2) or marginal (RR 0.9; 95% CI: 0.5, 1.7) serum vitamin B(12) status. Vitamin B(12) supplement users had a reduced risk of having deficient and marginal vitamin B(12) status (RR 0.3; 95% CI: 0.1, 0.8).

CONCLUSIONS

There is a relatively high prevalence of deficient and marginal serum vitamin B(12) concentrations among older New Zealanders. However, the prevalence of atrophic gastritis was low in the New Zealand elderly compared with other surveys. Although atrophic gastritis was a risk factor for low vitamin B(12) status, it did not fully explain the prevalence of low serum vitamin B(12).

Effects of once-a-week or daily folic acid supplementation on red blood cell folate concentrations in women

OBJECTIVE

Our aim was to determine if a once-a-week folic acid supplement increases women's red blood cell folate to concentrations (>905 nmol/l) that are associated with a low risk of bearing a child with a neural tube defect.

DESIGN

Randomized control trial.

SETTING

General community.

SUBJECTS

In total, 114 nonpregnant women (18-40 y) volunteers, with red blood cell folate concentrations between 295 and 905 nmol/l at screening.

INTERVENTION

Women were randomized to receive a once-a-week 2800 microg folic acid supplement, a daily 400 microg folic acid supplement or a daily placebo for 12 weeks.

RESULTS

The mean (95% CI) red blood cell folate concentrations increased during the 12-week intervention from 608 (553-668) to 900 (828-978) in the weekly folic acid group (P<0.05) and from 615 (560-677) to 1053 (957-1158) nmol/l in the daily group (P<0.05) during the trial. At week 12, 49% of women ingesting the weekly folic acid supplement had red blood cell folate concentrations greater than 905 nmol/l compared to 74% of women ingesting the daily supplement.

CONCLUSION

A once-a-week 2800 microg folic acid supplement can increase women's red blood cell folate to concentrations associated with a reduced risk of bearing a child with a neural tube defect, but is less effective than a 400 microg daily supplement. Use of a weekly folic acid supplement over at least 12 weeks before conception by women of child-bearing age may prevent neural tube defects.

FUNDING

The Otago Medical Research Foundation (Laurenson Award). Healtheries (New Zealand) provided the supplements.

Capture of attention in selective frequency listening

Four signal-detection experiments demonstrated robust stimulus-driven, or exogenous, attentional processes in selective frequency listening. Detection of just-above-threshold signal tones was consistently better when the, signal matched the frequency of an uninformative cue tone, even with relatively long cue-signal delays (Experiment 1) or when as few as 1 in 8 signals were at the cued frequency (Experiment 2). Experiments 3 and 4 compared performance with informative and uninformative cues. The involvement of intentional, or endogenous, processes was found to only slightly increase the size of the cuing effect beyond that evident with solely exogenous processes, although the attention band, a measure of how narrowly attention is focused, was found to be wider when cues were informative. The implications for models of auditory attention are discussed.

Pathophysiology of apolipoprotein E deficiency in mice: relevance to apo E-related disorders in humans

Apolipoprotein E (apo E) deficiency (or its abnormalities in humans) is associated with a series of pathological conditions including dyslipidemia, atherosclerosis, Alzheimer's disease, and shorter life span. The purpose of this study was to characterize these conditions in apo E-deficient C57BL/6J mice and relate them to human disorders. Deletion of apo E gene in mice is associated with changes in lipoprotein metabolism [plasma total cholesterol (TC) (>+400%), HDL cholesterol (-80%), HDL/TC, and HDL/LDL ratios (-93% and -96%, respectively), esterification rate in apo B-depleted plasma (+100%), plasma triglyceride (+200%), hepatic HMG-CoA reductase activity (-50%), hepatic cholesterol content (+30%)], decreased plasma homocyst(e)ine and glucose levels, and severe atherosclerosis and cutaneous xanthomatosis. Hepatic and lipoprotein lipase activities, hepatic LDL receptor function, and organ antioxidant capacity remain unchanged. Several histological/immunohistological stainings failed to detect potential markers for neurodegenerative disease in the brain of 37-wk-old male apo E-KO mice. Apo E-KO mice may have normal growth and development, but advanced atherosclerosis and xanthomatosis may indirectly reduce their life span. Apo E plays a crucial role in regulation of lipid metabolism and atherogenesis without affecting lipase activities, endogenous antioxidant capacity, or appearance of neurodegenerative markers in 37-wk-old male mice.

Selenium and zinc status are suboptimal in a sample of older New Zealand women in a community-based study

The importance of selenium and zinc in the immune functioning of the aged is widely recognized. Seniors in New Zealand are at particularly high risk of low selenium status because of the low selenium soil environment. The zinc status of the New Zealand elderly has never been assessed. In this cross-sectional study, the biochemical selenium, zinc and lipid levels, physical functional capacity and dietary intakes of 103 randomly selected free-living New Zealand women (mean age +/- SD, 75 +/- 3 y) were assessed. Among nonusers of selenium supplements (n = 80), 80% [95% confidence interval (CI): 70; 88%] had plasma selenium levels (0.85 +/- 0.23 micromol/L) below 1.00 micromol/L [ approximately 10% below mean plasma selenium necessary for full expression of glutathione peroxidase (GPx) activity in New Zealand subjects]. Plasma selenium was strongly correlated with GPx: r = 0.56; P < 0.0001. For nonusers of zinc supplements (n = 88), serum zinc concentrations were 12.4 +/- 1.4 micromol/L, with 12% (95% CI: 6; 21%) having levels below the cut-off value (10.7 micromol/L). Estimated mean daily selenium and zinc intakes were 34 +/- 10 microg and 8.7 +/- 2.0 mg, respectively. Subjects in the highest tertile of a functional capacity index had higher biochemical zinc and selenium values than those in the lowest tertile (P < 0.05). The correlation between plasma selenium and GPx indicates that selenium intake in these women is still insufficient for full expression of GPx activity. Lower serum zinc levels also appear to be prevalent. Because a suboptimal trace element status may be more common among those with a poor physical functioning, promotion of the consumption of nutrient dense foods or supplements to improve selenium and zinc status of elderly women in New Zealand may be beneficial.

Capture of attention in selective frequency listening

Four signal-detection experiments demonstrated robust stimulus-driven, or exogenous, attentional processes in selective frequency listening. Detection of just-above-threshold signal tones was consistently better when the, signal matched the frequency of an uninformative cue tone, even with relatively long cue-signal delays (Experiment 1) or when as few as 1 in 8 signals were at the cued frequency (Experiment 2). Experiments 3 and 4 compared performance with informative and uninformative cues. The involvement of intentional, or endogenous, processes was found to only slightly increase the size of the cuing effect beyond that evident with solely exogenous processes, although the attention band, a measure of how narrowly attention is focused, was found to be wider when cues were informative. The implications for models of auditory attention are discussed.

Potential for cross-transmission of Dictyocaulus viviparus between cattle and white-tailed deer

Development of an in vitro culture system for infectious Dictyocaulus viviparus larvae made it possible to study the potential cross-transmission of D. viviparus between white-tailed deer (Odocoileus virginianus) and cattle (Bos taurus). Between 26 September 1995-29 February 1996, six parasite-free bull calves were individually inoculated with 15 to 50 infective third stage larvae (L3)/kg of body weight cultured from adult D. viviparus collected from white-tailed deer. Three bull calves were simultaneously inoculated with 45 L3/kg of body weight recovered from cattle either by the Baermann technique or by in vitro culture as above. All three calves inoculated with the homologous cattle strain became patently infected while all six calves inoculated with the heterologous deer strain remained negative for the presence of D. viviparus in the feces and in the lungs upon necropsy.

Study of the assembly of vesicular stomatitis virus N protein: role of the P protein

To derive structural information about the vesicular stomatitis virus (VSV) nucleocapsid (N) protein, the N protein and the VSV phosphoprotein (P protein) were expressed together in Escherichia coli. The N and P proteins formed soluble protein complexes of various molar ratios when coexpressed. The major N/P protein complex was composed of 10 molecules of the N protein, 5 molecules of the P protein, and an RNA. A soluble N protein-RNA oligomer free of the P protein was isolated from the N/P protein-RNA complex using conditions of lowered pH. The molecular weight of the N protein-RNA oligomer, 513,879, as determined by analytical ultracentrifugation, showed that it was composed of 10 molecules of the N protein and an RNA of approximately 90 nucleotides. The N protein-RNA oligomer had the appearance of a disk with outer diameter, inner diameter, and thickness of 148 +/- 10 A, 78 +/- 9 A, and 83 +/- 8 A, respectively, as determined by electron microscopy. RNA in the complexes was protected from RNase digestion and was stable at pH 11. This verified that N/P protein complexes expressed in E. coli were competent for encapsidation. In addition to coexpression with the full-length P protein, the N protein was expressed with the C-terminal 72 amino acids of the P protein. This portion of the P protein was sufficient for binding to the N protein, maintaining it in a soluble state, and for assembly of N protein-RNA oligomers. With the results provided in this report, we propose a model for the assembly of an N/P protein-RNA oligomer.

Low erucic acid canola oil does not induce heart triglyceride accumulation in neonatal pigs fed formula

Canola oil is not approved for use in infant formula largely because of concerns over possible accumulation of triglyceride in heart as a result of the small amounts of erucic acid (22:1n-9) in the oil. Therefore, the concentration and composition of heart triglyceride were determined in piglets fed from birth for 10 (n = 4-6) or 18 (n = 6) d with formula containing about 50% energy fat as 100% canola oil (0.5% 22:1n-9) or 100% soybean oil, or 26% canola oil or soy oil (blend) with palm, high-oleic sunflower and coconut oil, providing amounts of 16:0 and 18:1 closer to milk, or a mix of soy, high-oleic sunflower and flaxseed oils with C16 and C18 fatty acids similar to canola oil but without 22:1. Biochemical analysis found no differences in heart triglyceride concentrations among the groups at 10 or 18 d. Assessment of heart triglycerides using Oil Red O staining in select treatments confirmed no differences between 10-d-old piglets fed formula with 100% canola oil (n = 4), 100% soy oil (n = 4), or the soy oil blend (n = 2). Levels of 22:1n-9 in heart triglyceride and phospholipid, however, were higher (P<0.01) in piglets fed 100% canola oil or the canola oil blend, with higher levels found in triglycerides compared with phospholipids. The modest accumulation of 22:1n-9 associated with feeding canola oil was not associated with biochemical evidence of heart triglyceride accumulation at 10 and 18 d.

Inhibition of B16 melanoma metastasis by overexpression of the cysteine proteinase inhibitor cystatin C

Progression to metastasis has been correlated with increased cysteine proteinase activity for a number of tumour types. One mechanism of cysteine proteinase regulation in normal cells is by natural protease inhibitors, the cystatins. Here we further characterize a transfected cell line showing increased cystatin C transcription driven by cytomegalovirus (CMV) promoter/enhancer sequences. Properties of this cystatin C altered cell line such as growth in vitro, lung colonization after tail vein injection in mice, production of cystatin, and cysteine proteinase inhibitor activities were examined. Although there was no difference between the growth rate of the cystatin transfected cell line and that of the control, there was a substantial difference in metastatic ability. No increase was noted in cystatin C secretion into the media for the cystatin C transfected cell line compared with the control transfected cell line. There was, however, a difference in cysteine protease inhibitor activity in the cell-free extracts. These results show that alteration of cystatin C levels by overexpression in B16 melanoma alters properties associated with metastasis.

Variability in the trans fatty acid content of foods within a food category: implications for estimation of dietary trans fatty acid intakes

OBJECTIVE

Currently, the published information on trans fatty acid composition of foods is incomplete and of questionable accuracy. Detailed fatty acid analysis of over 200 foods was undertaken for the purpose of determining the variability in trans fatty acid content among foods within a product category, and the significance of this variability to the estimation of trans fatty acids intakes from analysis of dietary intake data.

METHODS

The analysis of food fatty acids used gas-liquid chromatography with 100 m capillary columns and standardized methodologies for food sampling, fat extraction, separation and quantification of trans fatty acid isomers. For the purposes of this report, trans refers to all non-naturally occurring isomers including trans, cis-trans, geometric and positional isomers.

RESULTS

The results show that the amount of trans fatty acids varies considerably among foods within a category, reflecting differences in the fats and oils used in the manufacturing or preparation process. For example, the range of trans fatty acids in 17 brands of crackers was 23 to 51% total fatty acids, representing differences of from 1 to 13 g trans fatty acids per 100 g cracker. The large errors that may arise in estimates of the trans fatty acid intake of an individual are illustrated by analyses of the potential trans fatty acid intake in a sample diet, for each food as calculated using the minimum and maximum values for trans fatty acids within a given category. The results of these analyses show estimates of trans fatty acid intake from a low of 1.4 to 25.4 g a day for the same diet.

CONCLUSION

This study shows that the wide variability in trans fatty acid content of different foods may result in large errors in the estimation of trans fatty acid intake of individuals and, potentially, groups.

Patients' diets and preferences in a pediatric population with inflammatory bowel disease

PURPOSE

To determine the dietary practices of the pediatric inflammatory bowel disease population at the Children's Hospital of the Hamilton Health Sciences Corporation and the reported effectiveness of those diets.

PATIENTS AND METHODS

A questionnaire mailed to 153 pediatric patients was returned by 125 patients (76 Crohn's disease [CD] and 49 ulcerative colitis [UC] patients)--an 82% response rate.

RESULTS

The median age of respondents was 13 years, and 62% were male. Ninety per cent and 71% of CD and UC patients, respectively, had changed their diets since diagnosis. Caloric supplements (eg, BOOST [Mead Johnson Nutritionals]), sole source nutrition, low fibre and lactose-free diets were used by more than 15% of CD patients, whereas lactose-free, nonspicy, low acid, additive-free, caloric supplement and low fibre diets were used by more than 15% of UC patients. A diet supplement was more commonly used in CD patients (P < 0.05) and an additive-free diet in UC patients. Corn and corn products, nuts, milk and bran were avoided by more than 20% of CD and UC patients; however, more CD than UC patients avoided corn and corn products. In addition, UC patients (more than 20%) also avoided tomato, other dairy (nonfluid milk-based products and foods containing milk products), chocolate, cheese, wheat, tomato sauces and fruit juice. A benefit was reported for 103 of 141 reported diets, with the most commonly alleviated symptoms being abdominal pain, diarrhea and flatulence.

CONCLUSION

Many children with inflammatory bowel disease have altered their diets to manage their disease and have attributed symptomatic relief to these diets.

A three-day weighed food record and a semiquantitative food-frequency questionnaire are valid measures for assessing the folate and vitamin B-12 intakes of women aged 16 to 19 years

The purpose of this study was to validate a food-frequency questionnaire (FFQ) and a 3-d weighed food record (3d-WFR) by comparing nutrient intakes estimated using these methods with serum folate, RBC folate and serum vitamin B-12 concentrations in 105 females aged 16-19 y. During an early morning clinic visit, subjects completed a self-administered, 116-item FFQ, blood was collected and they were trained to complete a 3d-WFR. Folate intakes as determined by the 3d-WFR (r = 0.65, P < 0.01) exhibited a stronger association with serum folate than did intakes from the FFQ (r = 0.48, P < 0.01) (P = 0.017). The correlations between folate intakes and RBC folate as determined by the FFQ (r = 0.42, P < 0.01) and 3d-WFR (r = 0.50, P < 0.01) methods did not differ. Vitamin B-12 intakes showed only a modest association with serum vitamin B-12 when supplement users were included in the analyses (FFQ, r = 0.25, P < 0.05; 3d-WFR, r = 0.32, P < 0.05). After excluding supplement users from the analyses, the relationship between vitamin B-12 intakes as determined by FFQ and serum vitamin B-12 was no longer significant. Median daily folate intakes (346 vs. 212 microgram) and vitamin B-12 (4.9 vs. 1.9 microgram) estimated from the FFQ were higher than those obtained from the 3d-WFR. In sum, these data suggest that both the FFQ and 3d-WFR are valid measures of assessing the folate intake of young women, and both appear to be useful in determining vitamin B-12 intake when supplemental users are included. The markedly different conclusions about absolute folate and vitamin B-12 intakes obtained using these two dietary methodologies should be taken into consideration when making recommendations about optimal folate intakes in relation to disease prevention.

Oral contraceptives did not affect biochemical folate indexes and homocysteine concentrations in adolescent females

OBJECTIVE

The study was designed to determine the impact of currently available oral contraceptive agents (OCAs), smoking, and alcohol on biochemical indexes of folate and vitamin B-12 in adolescent females.

DESIGN

Subjects completed a 3-day weighed food record along with a detailed lifestyle questionnaire that included questions on OCA, cigarette, and alcohol use. After subjects had fasted overnight, blood samples were collected and analyzed for levels of serum and red blood cell (RBC) folate and serum B-12 and homocysteine.

SUBJECTS/SETTINGS

Two hundred twenty-nine adolescent females (aged 14 to 20 years) were recruited from southern Ontario, Canada, by advertisements in newspapers, high schools, universities, shopping malls, adolescent drop-in centers, and community groups.

STATISTICAL ANALYSES PERFORMED

Multiple regression models were used to determine the effect of lifestyle factors and covariates (e.g., dietary folate intake, supplemental folate intake, and age) on biochemical indexes.

RESULTS

OCA use, alcohol use, and smoking were not significantly associated with lower serum or RBC folate levels, after controlling for folate intake. Serum homocysteine levels were not associated with smoking or OCA use; however, we estimated a 13% higher concentration among alcohol users than nonusers. Smoking and alcohol use were not associated with serum B-12 levels, but OCA use was associated with an estimated 33% lower serum B-12 level than nonuse.

APPLICATIONS

Our findings provide no evidence to suggest that currently available OCAs have a negative impact on the folate status of adolescent females; thus, dietary advice designed to specifically encourage an increase in folate intake among adolescents who use OCAs is not supported. In contrast, serum B-12 levels were lower among OCA users than nonusers, which suggests that an interaction between OCA and some vitamins may persist. The suboptimal biochemical folate indexes of smokers may have more to do with the dietary quality of smokers than previously appreciated. Thus, efforts to improve dietary folate intakes of adolescents who smoke may be an important strategy for improving the folate status of young women.

Role of sialyloligosaccharide binding in Theiler's virus persistence

Theiler's murine encephalomyelitis viruses (TMEVs) belong to the Picornaviridae family and are divided into two groups, typified by strain GDVII virus and members of the TO (Theiler's original) group. The highly virulent GDVII group causes acute encephalitis in mice, while the TO group is less virulent and causes a chronic demyelinating disease which is associated with viral persistence in mice. This persistent central nervous system infection with demyelination resembles multiple sclerosis (MS) in humans and has thus become an important model for studying MS. It has been shown that some of the determinants associated with viral persistence are located on the capsid proteins of the TO group. Structural comparisons of two persistent strains (BeAn and DA) and a highly virulent strain (GDVII) showed that the most significant structural variations between these two groups of viruses are located on the sites that may influence virus binding to cellular receptors. Most animal viruses attach to specific cellular receptors that, in part, determine host range and tissue tropism. In this study, atomic models of TMEV chimeras were built with the known structures of GDVII, BeAn, and DA viruses. Comparisons among the known GDVII, BeAn, and DA structures as well as the predicted models for the TMEV chimeras suggested that a gap on the capsid surface next to the putative receptor binding site, composed of residues from VP1 and VP2, may be important in determining viral persistence by influencing virus attachment to cellular receptors, such as sialyloligosaccharides. Our results showed that sialyllactose, the first three sugar molecules of common oligosaccharides on the surface of mammalian cells, inhibits virus binding to the host cell and infection with the persistent BeAn virus but not the nonpersistent GDVII and chimera 39 viruses.

Association between dietary fiber intake and the folate status of a group of female adolescents

The main objective of this study was to assess the association between dietary fiber intake and the folate status of Canadian female adolescents. We also assessed dietary folate intakes and evaluated the prevalence of biochemical folate deficiency in these subjects. Female adolescents aged 14-19 y (n = 224) were recruited and fasting blood samples were collected. Dietary intakes (3-d food record) were recorded and participants were classified as lactoovovegetarians, semivegetarians, or omnivores on the basis of food-consumption patterns assessed with food-frequency questionnaires. Fourteen percent, 17%, and 26% of lactoovovegetarians, semivegetarians, and omnivores, respectively, had dietary folate intakes below their predicted requirements; 1%, 4%, and 23%, respectively, had serum folate concentrations indicative of deficiency. Despite low dietary folate intakes and serum folate concentrations, few subjects had homocysteine concentrations indicative of deficiency, suggesting that the degree of folate depletion had not yet produced functional consequences. Most important, results suggest that the consumption of nonstarch polysaccharide is significantly associated with serum folate concentrations (P < 0.001). For each 1-g increase in nonstarch polysaccharide intake, a 1.8% increase in serum folate concentration is expected. In summary, we propose that an increase in nonstarch polysaccharide intake may promote the intestinal biosynthesis of folate, providing a complementary strategy to enhance the folate nutriture of humans.

Advanced practice nurses: change agents for clinical practice

The article presents the role of advanced practice nurses as change agents in the clinical setting. Research utilization is needed to shape and form the basis of nursing practice. As change agents, the advanced practice nurses in one institution established a research-based minimal stimulation protocol for the very low-birth weight infant and implemented it using a video presentation. Knowledge of change theory, research utilization, and video production was necessary in making this project a success.

Synthetic-aperture-radar imaging with a solid-state laser

We report the operation of an imaging Nd:YAG microchip-laser synthetic-aperture radar, with which we imaged two-dimensional (2-D) models of military targets. The images obtained showed spatial resolution significantly better than the diffraction limit of the real aperture in the along-track dimension. The signal processing is described, and the measurement sensitivity is both predicted and verified. In addition, 2-D images with high resolution in both dimensions were generated by using an asymmetric aperture to match the along-track synthetic-aperture resolution with the across-track diffraction-limited resolution.

A cytotoxic diacetylene from Dendropanax arboreus

The crude ethanol extract from the leaves of Dendropanax arboreus (Araliaceae) from Monteverde, Costa Rica, exhibits cytotoxic activity against Hep-G2, A-431, H-4IIE, and L-1210 tumor cell lines, but is not toxic against normal hepatocytes. The active component has been isolated by activity-directed separation and identified by 1H- and 13C-NMR spectroscopy as the acetylenic compound cis-1,9,16-heptadecatriene-4,6-diyne-3,8-diol.

An antibacterial vitamin E derivative from Tovomitopsis psychotriifolia

The crude ethanol extract from the leaves of Tovomitopsis psychotriifolia (Clusiaceae) exhibits antibacterial activity against Bacillus cereus, Staphylococcus aureus, and Pseudomonas aeruginosa. The biologically active agent in the extract has been isolated by chromatographic techniques and identified by NMR spectroscopy as trans-delta-tocotrienoloic acid.

Antigenic analysis of Dictyocaulus viviparus by use of test-positive bovine sera

An antigen extract of Dictyocaulus viviparus was analyzed by use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the antigen-recognition patterns of serum antibody from cattle not infected, cattle infected with D viviparus, and cattle with unknown history of D viviparus were analyzed by the use of ELISA and western blotting techniques. Cross-reactive antibody-recognition patterns were determined by comparing western blots of D viviparus-positive sera with blots of D viviparus-negative sera obtained from cattle singly infected with Bunostomum phlebotomum, Cooperia oncophora, C punctata, Nematodirus helvetianus, Oesophagostomum radiatum, or Ostertagia ostertagi. Five antigen bands unique to D viviparus were identified, and their frequency of appearance in western blots of sera from verified D viviparus-positive and -negative cattle, and sera from cattle exposed to the parasite, but with unknown D viviparus immune status, were determined. Of the 5 antigens unique to D viviparus, 29- and 19-kd bands had the highest frequencies of reaction (45.9 and 59.0%, respectively) with the test sera. These bands had strong reactivity with sera containing antibodies to D viviparus and did not react with the heterologous sera. We conclude that the 29- and 19-kd antigens may be useful for developing an improved serodiagnostic test for D viviparus infections in cattle.

Solid-state laser synthetic aperture radar

Here we report the operation of an optical synthetic aperture radar employing, for the first time to our knowledge, a solid-state laser as the source. The experimental data-acquisition and digital processing techniques are described, by which spatial resolution superior to that limited by diffraction is demonstrated.

Monoclonal IgM rheumatoid factor-like anti-globulins enhance the inhibitory effects of Plasmodium falciparum-specific monoclonal antibodies in vitro

Monoclonal IgM rheumatoid factor-like anti-globulins were produced by in vitro stimulation of naive BALB/c spleen cells with lipopolysaccharide, and by hyperimmunization of mice with merozoites of Plasmodium falciparum, followed by fusion of the spleen cells to mouse myelomas. In vitro, these anti-globulins augmented the inhibitory effects of P. falciparum-specific polyclonal mouse sera and monoclonal IgG1 and IgG2b antibodies by binding to Fc fragments of IgG molecules attached to blood-stage parasites. In some instances, the presence of anti-globulins correlated with an increase in the number of schizonts which failed to disperse merozoites. In other cases, parasitaemia remained low in the absence of the schizont inhibition phenomenon, suggesting that anti-globulins contribute to host cell protection not only by agglutinating merozoites, but also by increasing the density of the antibody coat surrounding the parasites, thus interfering with parasite receptor-erythrocyte ligand interactions. The anti-globulins were not inhibitory when added to parasite cultures containing IgG not specific for P. falciparum. These results may help explain the function of IgM anti-globulins found at elevated serum levels in some patients with malaria or other chronic infectious diseases.

Identification of common surface antigens among Babesia bigemina isolates by using monoclonal antibodies

A group of monoclonal antibodies (MAb) was used to immunochemically characterize Babesia bigemina surface components. Two surface reactive MAb by an IFAT test were subsequently shown to bind to epitopes on the external surface of the parasite plasma membrane as evidenced by immunoelectron microscopy. Parasite components with relative sizes of 68, 62, 60, 58, 56, 54, 51, 49, 48, 47, 43, 36 kDa were identified with the group of MAb in at least 6 geographically different B. bigemina isolates. The antigenic components were demonstrated to be species-specific and apparently predominant. Both polyclonal antibodies (immune bovine serum) and highly diluted MAb specifically reacted with such bands producing a strong signal in Western blots.

Phosphorimeters for analysis of decay profiles and real time monitoring of exponential decay and oxygen concentrations

A phosphorimeter which can be assembled at low cost from mainly commercially available components and which has better time resolution, data acquisition rate, sensitivity, and flexibility than commercially available instruments is described. As a phosphorescence analyzer the instrument can measure phosphorescence lifetimes ranging from approximately 30 microseconds to seconds from samples with variable intensity, excitation, and emission spectra and which may follow complex decay behavior. Configured as a phosphorescence monitor it is designed for fast, repetitive calculation of phosphorescence lifetime, assuming single-exponential decay, and can be used to calculate oxygen concentration in biological samples in real time.

The oxygen dependence of mitochondrial oxidative phosphorylation measured by a new optical method for measuring oxygen concentration

Oxygen-dependent quenching of phosphorescence has been used to measure the dependence of mitochondrial oxidative phosphorylation on oxygen concentration in suspensions of isolated rat liver mitochondria. An instrument has been designed which simultaneously monitors the phosphorescence lifetime of a fluorophor and the reduction of cytochrome c by dual wavelength spectrophotometry. The phosphorescence lifetime method gives very rapid (less than 100 ms) measure of the oxygen concentration (Vanderkooi, J. M., Maniara, G., Green, T. J., and Wilson, D. F. (1987) J. Biol. Chem. 262, 5476-5482) from concentrations characteristic of air-saturated media to as low as 2 x 10(-8) M. The results may be summarized as follows. For well coupled rat liver mitochondria at pH 7.0 and in the presence of ATP, as the oxygen concentration was lowered, increased cytochrome c reduction was observed to begin at oxygen concentrations greater than 20 microM. For mitochondria in the presence of uncoupler, cytochrome c reduction began at oxygen concentrations less than 1.0 microM. The oxygen dependence of reduction of cytochrome c in well coupled mitochondria treated with ATP was strongly dependent on the pH of the suspending medium. Reduction of cytochrome c began at higher oxygen concentrations as the pH was made more alkaline. The oxygen concentration for half-maximal respiratory rates was much larger for well coupled mitochondria treated with ATP (approximately 0.7 microM) than for mitochondria treated with uncoupler (less than 0.1 microM). It is concluded that the oxygen dependence of mitochondrial oxidative phosphorylation is such that mitochondria could function in their proposed role of tissue oxygen sensors for regulation of such diverse functions as local blood flow and electrical activity in the carotid body.

An optical method for measurement of dioxygen concentration based upon quenching of phosphorescence

An optical method for measuring oxygen concentrations in aqueous solutions is described. This method is based upon the oxygen-dependent quenching of phosphorescence. Phosphorescence excitation and emission spectra and lifetimes of some of the probe molecules suitable for measurement of oxygen in aqueous solutions are given. The probes include fluorescein derivatives, 4'5'-diiodofluorescein, eosin Y, 5(and 6)-carboxyeosin, erythrosin, and 5(and 6)-carboxyerythrosin as well as the Zn(II), Y(III), Sn(IV), Lu(III), and Pd(II) derivatives of meso-tetra-(4-sulfonatophenyl)-porphine, meso-tetra-(N-methyl-4-pyridyl)-porphine and coproporphyrin. The phosphorescence lifetimes of the given probes were found to depend upon the oxygen concentration by a simple Stern-Volmer relationship with a quenching constant of approximately 10(9) M-1 S-1. Binding of the molecules to bovine serum albumin decreased the quenching constant for oxygen by approximately an order of magnitude and also inhibited probe self-quenching, indicating that at the protein binding site the probes are somewhat protected from collision with quenchers. The use of this optical method for measuring oxygen is demonstrated for reactions catalyzed by glucose oxidase and by cytochrome c oxidase. It is shown that, using this method oxygen concentrations can be measured from approximately 250 microM (air saturation) down to the nanomolar range.

A sensitive urea-silver stain method for detecting trace quantities of separated proteins in polyacrylamide gels

An ultrasensitive method using a urea-silver staining procedure to detect trace quantities of proteins in polyacrylamide gels (PAGE) is described. This technique is sensitive enough to detect picogram quantities of proteins resolved on sodium dodecyl sulfate-polyacrylamide gels. The major advantages of our method are that it provides a clear background and it is more sensitive than other techniques allowing it to substitute for radioisotopic techniques in some cases.

A versatile and sensitive method for measuring oxygen

Oxygen dependence of the lifetime of the excited triplet state of phosphorescent molecules can be used to measure the oxygen concentration in aqueous media. These measurements are insensitive to much of the optical interference that limits the usefulness of measurements based on the oxygen dependent quenching of luminescence intensity. The measurements also extend to significantly lower oxygen concentrations than are normally attainable using oxygen electrodes. The phosphorescence lifetimes can be accurately measured from a few microseconds to seconds, permitting a wide dynamic range of oxygen concentration measurements. With currently available probes, for example, it is possible to make continuous measurement of oxygen concentrations from 10(-4) M to 10(-8) M in a single experiment.

Specific detection of Plasmodium falciparum malaria by a molecularly cloned DNA probe

A highly repeated DNA sequence from Plasmodium falciparum was cloned and used as a probe in molecular hybridization to detect malaria. Our results indicate that the probe is specific to P. falciparum but not to other species of Plasmodium and is extremely sensitive. As little as a 20 pg parasite DNA, which is equivalent to about 1000 parasites can be detected. The cloned DNA can be used as a diagnostic tool to follow the course of infection of falciparum malaria.