Validating the NIH LDL-C equation for provincial implementation in Alberta

BACKGROUND

LDL-C, a cardiovascular disease risk assessment biomarker, is commonly calculated using the Friedewald equation. The NIH equation overcomes several limitations of the Friedewald equation. Consistent with the Canadian Society of Clinical Chemists (CSCC) lipid reporting recommendations, we assessed the NIH LDL-C equation in Alberta prior to its provincial implementation.

METHODS

1-year (01/01/2021-12/31/2021) of lipid results (n = 1,486,584 after data cleaning) were obtained from five analytical instrument groups used across Alberta. Analyses were performed on all data and after separating by age, analytical instrument group, and fasting status. The correlation between Friedewald- and NIH-calculated LDL-C and between Friedewald- and NIH-calculated LDL-C difference and each lipid parameter, was determined. The frequency of unreportable/inaccurate LDL-C results was compared between the two equations. The concordance between the two equations and with non-HDL-C was determined at LDL-C thresholds. Lastly, LDL-C calculated by Friedewald, NIH, and Martin-Hopkins equations was compared to density-gradient ultracentrifugation.

RESULTS

Friedewald- and NIH-calculated LDL-C exhibit the strongest correlation when triglycerides ≤ 4.52 mmol/L. The difference between Friedewald- and NIH-calculated LDL-C increases with decreasing LDL-C concentration. The NIH equation yields fewer inaccurate results (0.35 % vs. 22.0 %). The percent agreement between equations was > 96 % at all LDL-C thresholds, suggesting most patients will not require treatment changes. NIH-calculated LDL-C exhibited better agreement with non-HDL-C when triglycerides ≤ 9.04 mmol/L and better correlated with LDL-C measured by ultracentrifugation (r2 = 0.926 vs. 0.775 (Friedewald) and 0.863 (Martin-Hopkins)). Results were consistent across age, analytical instrument group, and fasting status.

CONCLUSIONS

Our findings demonstrate the benefits of implementing the NIH equation across Alberta.

Hemoglobin Variant in Disguise

BACKGROUND

Hemoglobinopathies include thalassemia syndromes, where production of one or more globin subunits of hemoglobin (Hb) is reduced, and structural Hb variants. Over 1000 disorders of Hb synthesis and/or structure have been identified and characterized, with phenotypes ranging from having severe clinical manifestations to clinically silent. Various analytical methods are used to phenotypically detect Hb variants. However, molecular genetic analysis is a more definitive method for Hb variant identification.

CASE REPORT

Here, we report a case of a 23-month-old male with results from capillary electrophoresis, gel electrophoresis (acid and alkaline), and high-performance liquid chromatography most consistent with HbS trait. Specifically, capillary electrophoresis showed slightly elevated HbF and HbA2, HbA of 39.4% and HbS of 48.5%. The HbS percentage was consistently higher than expected (typically 30-40%) for HbS trait with no concurrent thalassemic indices. The patient has not experienced any clinical complications due to the hemoglobinopathy and he is thriving.

CONCLUSION

Molecular genetic analysis revealed the presence of compound heterozygosity for HbS and Hb Olupona. Hb Olupona is an extremely rare beta-chain variant that appears as HbA on all three common methods used for phenotypic Hb analysis. When the fractional concentration of Hb variants is unusual, more definitive methods should be used, such as mass spectrometry or molecular genetic testing. In this case, incorrectly reporting this result as HbS trait is unlikely to have a significant clinical impact, as current evidence suggests Hb Olupona is not a clinically significant variant.

Variation in Processes and Reporting of Cerebrospinal Fluid Oligoclonal Banding and Associated Tests and Calculated Indices across Canadian Clinical Laboratories

OBJECTIVES

Multiple sclerosis is diagnosed based on clinical and laboratory findings, including cerebrospinal fluid (CSF) oligoclonal banding (OCB) analysis. The lack of updated CSF OCB laboratory guidelines in Canada has likely led to variation in processes and reporting across clinical laboratories. As a first step to developing harmonized laboratory recommendations, we examined current CSF OCB processes, reporting, and interpretation across all Canadian clinical laboratories currently performing this test.

DESIGN AND METHODS

A survey of 39 questions was sent to clinical chemists at all 13 Canadian clinical laboratories performing CSF OCB analysis. The survey included questions regarding quality control processes, reporting practices for CSF gel electrophoresis pattern interpretation, and associated tests and calculated indices.

RESULTS

The survey response rate was 100%. Most (10/13) laboratories use ≥2 CSF-specific bands (2017 McDonald Criteria) as their CSF OCB positivity cut-off and only 2/13 report the number of bands with every report. Most (8/13 and 9/13) laboratories report an inflammatory response pattern and monoclonal gammopathy pattern, respectively. However, the process for reporting and/or confirming a monoclonal gammopathy varies widely. Variation was observed for reference intervals, units, and the panel of reported associated tests and calculated indices. The maximum acceptable time interval between paired CSF and serum collections varied from 24 hours to no limit.

CONCLUSIONS

Profound variation exists in processes, reporting, and interpretation of CSF OCB and associated tests and indices across Canadian clinical laboratories. Harmonization of CSF OCB analysis is required to ensure continuity and quality of patient care. Our detailed assessment of current practice variation highlights the need for clinical stakeholder engagement and further data analysis to support optimal interpretation and reporting practices, which will aid in developing harmonized laboratory recommendations.

Care Coordination of Autism Spectrum Disorder: A Solution-Focused Approach

The expanding practice of multi-disciplinary care to address the complex nature of Autism Spectrum Disorder (ASD) suggests that there is a need for a means of coordinating care that transcends the disciplinary distinctions of relevant ASD treatment providers. As ASD services become more specialized, there is a growing need for effective care coordination with providers across the systems of care. Nursing professionals are ideally qualified to support families affected by ASD, as they provide a necessary holistic lens of health and wellbeing to obtain the appropriate treatments. Solution-focused brief therapy has been applied to a growing number of clinical settings, indicating solution-focused techniques are applicable to the various contexts associated with ASD treatments. We provide a case presentation to demonstrate a solution-focused approach to address ASD-related concerns within the family that are generalizable to coordination of care.

Past, present, and future for biologic intervention in atopic dermatitis

Atopic dermatitis (AD) is a debilitating disease that significantly alters the quality of life for one in four children and one in 10 adults. Current management of AD utilizes combinations of treatments to symptomatically alleviate disease by suppressing the inflammatory response and restoring barrier function in the skin, reducing disease exacerbation and flare, and preventing secondary skin infections. Resolution is temporary and long-term usage of these treatments can be associated with significant side-effects. Antibody therapies previously approved for inflammatory diseases have been opportunistically evaluated in patients with atopic dermatitis; however, they often failed to demonstrate a significant clinical benefit. Monoclonal antibodies currently in development offer hope to those individuals suffering from the disease by specifically targeting immune and molecular pathways important for the pathogenesis of atopic dermatitis. Here, we review the underlying biological pathways and the state of the art in therapeutics in AD.

Phylogenetic Diversity of Rhizoctonia solani Associated with Canola and Wheat in Alberta, Manitoba, and Saskatchewan

Rhizoctonia solani is a damaging soilborne pathogen, which affects most field crops in the Canadian provinces of Alberta, Manitoba, and Saskatchewan. The objective of this study was to conduct a phylogenetic comparison of isolates of R. solani collected from a previous survey in the major canola- and wheat-growing regions of western Canada. A total of 128 multinucleate isolates from a previous survey were identified by internal transcribed spacer (ITS) sequence and compared to anastomosis group (AG) results. The multinucleate isolates of R. solani were grouped into eight distinct clades. Each clade corresponded to a specific AG with the exception of two distinct clades that were observed for isolates classified as AG 2-1 by anastomosis testing. While most isolates of AG 5 clustered together according to ITS sequences, three isolates classified by anastomosis grouping as AG 5 grouped with AG 2-1, AG 4, and a binucleate Rhizoctonia sp. in the phylogenetic analysis. In most instances, the results from AG tests were consistent with ITS sequence, but there were still several cases where isolates were inconsistently classified or failed to undergo anastomosis with any of the tester strains used in this study. This provides support for the use of the ITS region as a valuable tool for rapid identification of R. solani isolates to their respective AGs.

Evaluation of Air Sampling and Detection Methods to Quantify Airborne Ascospores of Sclerotinia sclerotiorum

Detection and quantification of airborne ascospores as a component of the Sclerotinia rot of carrot (SRC) forecast model is currently accomplished using the blue plate test (BPT), which uses Sclerotinia semiselective medium (SSM). A quantitative polymerase chain reaction (qPCR) assay was developed to reduce the time to specifically quantify ascospores of Sclerotinia sclerotiorum from air samples collected using a Burkard Multi-Vial Cyclone Sampler. The qPCR assay was highly sensitive and detected DNA from 0.5 to 5 × 10⁴ ascospores within a linear range (R² = 0.99). The qPCR assay was used to quantify ascospores of S. sclerotiorum in air samples collected over three growing seasons. Initial SRC disease was observed 8 and 34 days following detection of 9.5 and 2 ascospores m^-3 of air, respectively. Results from air samples collected using an Andersen N6 Sampler and the qPCR assay were compared with the BPT. Ascospore counts from a Burkard Sampler coupled with the qPCR assay and the BPT followed similar trends. In general, fewer ascospores were detected and bioaerosol sampling efficiency was low using an Anderson Sampler. Three days were required to confirm the number of ascospores using SSM in the BPT and with an Andersen Sampler, whereas results from a Burkard Sampler coupled with the qPCR assay can provide results within 5 h of air sampling. The choice of method will depend on the available resources.

Methanogenesis from ethanol by defined mixed continuous cultures

Methanogenesis from ethanol by defined mixed continuous cultures was studied. Under sulfate-free conditions, a Desulfovibrio strain was used as the ethanol-degrading species producing acetic acid and hydrogen. In a two-membered mutualistic coculture, the hydrogen was converted to methane by a Methanobacterium sp. and pH was maintained at neutrality by the addition of alkali. Introduction of a third species, the acetate-utilizing Methanosarcina mazei, obviated the need for external pH control. Methanogenesis by the co-and triculture was studied at various dilution rates in the steady state. The mutualistic coculture performed like a composite single species, as predicted from the theory of mutualistic interactions. Coupling between the mutualistic coculture and the acetate-utilizing methanogen was less tight. Increasing the dilution rate destabilized the triculture; at low dilution rates, instability was soon recovered, but at higher dilution rates imbalance between the rates of production and removal of acetic acid led to a drop in pH. Flocs formed in the triculture. An annulus of the Methanobacterium sp. and Desulfovibrio sp. was retained around the Methanosarcina sp. by strands of material probably derived from the Methanosarcina sp.

Salmonella must be viable in order to attach to the surface of prepared vegetable tissues

AIMS

The aims of the current study were to explore the site of bacterial attachment to vegetable tissues and to investigate the hypothesis that Salmonella must be living in order to attach to this site(s).

METHODS AND RESULTS

Scanning electron micrographs of intact potato cells showed that Salm. serotype Typhimurium attached to cell-wall junctions; suggesting a high-level of site selectivity. Inactivation of Salm. Typhimurium using heat, ethanol, formalin or Kanamycin resulted in cells that could be no longer attached to these sites. Attachment of a Gfp(+) strain of Salm. Typhimurium to cell-wall material (CWM) was examined via flow cytometric analysis. Only live Salm. Typhimurium attached to the CWM.

CONCLUSIONS

Salmonella serotype Typhimurium must be metabolically active to ensure attachment to vegetable tissues. Attachment preferentially occurs at the plant cell-wall junction and the cell-wall components found here, including pectate, may provide a receptor site for bacterial attachment.

SIGNIFICANCE AND IMPACT OF THE STUDY

Further studies into individual plant cell-wall components may yield the specific bacterial receptor site in vegetable tissues. This information could in turn lead to the development of more targeted and effective decontamination protocols that block this site of attachment.

During infection of epithelial cells Salmonella enterica serovar Typhimurium undergoes a time-dependent transcriptional adaptation that results in simultaneous expression of three type 3 secretion systems

The biogenesis of the Salmonella-containing vacuole within mammalian cells has been intensively studied over recent years. However, the ability of Salmonella to sense and adapt to the intracellular environment of different types of host cells has received much less attention. To address this issue, we report the transcriptome of Salmonella enterica serovar Typhimurium SL1344 within epithelial cells and show comparisons with Salmonella gene expression inside macrophages. We report that S. Typhimurium expresses a characteristic intracellular transcriptomic signature in response to the environments it encounters within different cell types. The signature involves the upregulation of the mgtBC, pstACS and iro genes for magnesium, phosphate and iron uptake, and Salmonella pathogenicity island 2 (SPI2). Surprisingly, in addition to SPI2, the invasion-associated SPI1 pathogenicity island and the genes involved in flagellar biosynthesis were expressed inside epithelial cells at later stages of the infection, while they were constantly downregulated in macrophage-like cells. To our knowledge, this is the first report of the simultaneous transcription of all three Type Three Secretion Systems (T3SS) within an intracellular Salmonella population. We discovered that S. Typhimurium strain SL1344 was strongly cytotoxic to epithelial cells after 6 h of infection and hypothesize that the time-dependent changes in Salmonella gene expression within epithelial cells reflects the bacterial response to host cells that have been injured by the infection process.

The effect of environment on endosperm cell-wall development in Triticum aestivum during grain filling: an infrared spectroscopic imaging study

One of the major factors contributing to the failure of new wheat varieties is seasonal variability in end-use quality. Consequently, it is important to produce varieties which are robust and stable over a range of environmental conditions. Recently developed sample preparation methods have allowed the application of FT-IR spectroscopic imaging methods to the analysis of wheat endosperm cell wall composition, allowing the spatial distribution of structural components to be determined without the limitations of conventional chemical analysis. The advantages of the methods, described in this paper, are that they determine the composition of endosperm cell walls in situ and with minimal modification during preparation. Two bread-making wheat cultivars, Spark and Rialto, were selected to determine the impact of environmental conditions on the cell-wall composition of the starchy endosperm of the developing and mature grain, focusing on the period of grain filling (starting at about 14 days after anthesis). Studies carried out over two successive seasons show that the structure of the arabinoxylans in the endosperm cell walls changes from a highly branched form to a less branched form. Furthermore, during development the rate of restructuring was faster when the plants were grown at higher temperature with restricted water availability from 14 days after anthesis with differences in the rate of restructuring occurring between the two cultivars.

FTIR imaging of wheat endosperm cell walls in situ reveals compositional and architectural heterogeneity related to grain hardness

Endosperm cell walls of cultivars of wheat (Triticum aestivum L.) selected for their endosperm texture (two soft and two hard) were analysed in situ by Fourier transform infrared (FTIR) microspectroscopy. FTIR imaging coupled with statistical analysis was used to map the compositional and structural heterogeneity within transverse sections from which cell contents had been removed by sonication. In the majority of grains analysed, two distinct populations of endosperm cells could be identified by spectral features that were related to cell morphology and age, regardless of cultivar. The main cell-wall component responsible for these differences was the polysaccharide arabinoxylan. In a few samples, this heterogeneity was absent, for reasons that are not understood, but this was not correlated to endosperm texture or growth conditions. Within the same population of endosperm cells, cell walls of hard endosperm could be distinguished from those of soft endosperm by their spectral features. Compared to hard cultivars, the peripheral endosperm of soft cultivars was characterised by a higher amount of polymer, whose spectral feature was similar to water-extractable arabinoxylan. In contrast, no specific compound has been identified in the central endosperm: structural differences within the polysaccharides probably contribute to the distinction between hard and soft cultivars. In developing grain, a clear difference in the composition of the endosperm cell walls of hard and soft wheat cultivars was observed as early as 15 days after anthesis.

Synthetic and naturally occurring COX-2 inhibitors suppress proliferation in a human oesophageal adenocarcinoma cell line (OE33) by inducing apoptosis and cell cycle arrest

Epidemiological studies suggest that the use of NSAIDs and/or a high intake of fruit and vegetables reduce the risk of oesophageal adenocarcinoma. Since COX-2 is up-regulated in Barrett's oesophageal carcinogenesis, the protective effect of NSAIDs and natural food components might reflect COX-2 inhibition. We explored the effects of quercetin, a natural flavonoid with a potent COX-2 inhibitory activity, and two commercially available selective COX-2 inhibitors (NS-398 and nimesulide) on cell proliferation, apoptosis, PGE2 production and COX-2 mRNA expression in a human oesophageal adenocarcinoma cell line (OE33). Changes in the relative numbers of adherent and floating cells were quantified and apoptotic cells were identified using ethidium bromide and acridine orange staining under fluorescence microscopy. Flow cytometric analysis of adherent and floating cells was used to quantify apoptosis and to examine the effects of the agents on the cell cycle. After 48 h exposure at concentrations of > or =1 microM both COX-2 inhibitors and quercetin suppressed cell proliferation (P < 0.01) and increased the fraction of floating apoptotic cells. At higher concentrations (50 microM) and longer exposure (48 h) the effects of quercetin were significantly greater than those of the selective COX-2 inhibitors (P < 0.01). Cell cycle analyses showed that quercetin blocked cells in S phase, while the selective COX-2 inhibitors blocked cells in G1/S interphase. COX-2 mRNA expression was suppressed by quercetin and the synthetic COX-2 inhibitors in a time- and dose-dependent manner. Quercetin and the synthetic COX-2 inhibitors (10 microM) suppressed PGE2 production by approximately 70% after 24 h exposure (P < 0.001). We conclude that OE33 is a useful model for the study of COX-2 expression and associated phenomena in human adenocarcinoma cells. Synthetic COX-2 inhibitors and the food-borne flavonoid quercetin suppress proliferation, induce apoptosis and cell cycle block in human oesophageal adenocarcinoma cells in vitro, and future studies should assess their effects in vivo.

Microbial colonization of naturally black olives during fermentation and associated biochemical activities in the cover brine

AIMS

To establish the site of microbial growth on naturally black fermented table olives, and to monitor the population dynamics of yeasts and selected micro-organisms together with the changes in organic acid profile and pH in the cover brine during fermentation.

METHODS AND RESULTS

During fermentation, the numbers of Enterobacteriaceae and Pseudomonas spp. in the brine decreased whilst lactic acid bacteria and yeast populations increased. Scanning electron microscopy showed that a yeast-rich biofilm developed on the epicuticular wax of the olive skin during fermentation. Yeasts also predominated in the stomatal openings, but bacteria were more numerous in intercellular spaces in the sub-stomatal flesh. Citric, malic and tartaric acids were the major organic acids accumulating in the brine during fermentation.

CONCLUSIONS

Micro-organisms associated with the skin, stomata and flesh in fermenting black olives may experience different local conditions to those prevailing in the cover brine.

SIGNIFICANCE AND IMPACT OF THE STUDY

These are the first observations of the micro-organisms associated with the fruit of naturally fermented black olives and of the accumulation of specific organic acids during fermentation.

Pectin distribution at the surface of potato parenchyma cells in relation to cell-cell adhesion

The crispness of fruits and vegetables is dependent, predominantly, on the maintenance of cell adhesion. There is a growing body of evidence to suggest that cell adhesion in plants is controlled at the edge of cell faces rather than across the entire cell surface. The aim of the current study has been to exploit antibody-labeling techniques in conjunction with methods that induce cell separation to explore the distribution of highly esterified and weakly esterified pectic polysaccharides on the cell surface. Potato parenchyma tissue was subjected to cooking and chemical treatments, which induced softening through cell separation. Scanning electron microscopy (SEM) revealed characteristic patterns on the surface of these separated cells, which outlined the imprint of neighboring cells. Monoclonal antibodies, JIM5 and JIM7, were used to locate weakly esterified and highly esterified pectin by silver-enhanced immunogold SEM. The edge-of-face structures labeled strongly with JIM5 but not JIM7, indicating that they contained polygalacturonic acid of low ester content. In addition, adhesion of the middle lamella to the face of the primary wall was found to differ from adhesion at the edge of each cell face. This, in conjunction with the antibody-labeling observations, complements previous transmission electron microscopy studies and is consistent with the edge-of-face regions having a specialist role in cell adhesion.

Rerouting the plant phenylpropanoid pathway by expression of a novel bacterial enoyl-CoA hydratase/lyase enzyme function

The gene for a bacterial enoyl-CoA hydratase (crotonase) homolog (HCHL) previously shown to convert 4-coumaroyl-CoA, caffeoyl-CoA, and feruloyl-CoA to the corresponding hydroxybenzaldehydes in vitro provided an opportunity to subvert the plant phenylpropanoid pathway and channel carbon flux through 4-hydroxybenzaldehyde and the important flavor compound 4-hydroxy-3-methoxybenzaldehyde (vanillin). Expression of the Pseudomonas fluorescens AN103 HCHL gene in two generations of tobacco plants caused the development of phenotypic abnormalities, including stunting, interveinal chlorosis and senescence, curled leaf margins, low pollen production, and male sterility. In second generation progeny, the phenotype segregated with the transgene and transgenic siblings exhibited orange/red coloration of the vascular ring, distorted cells in the xylem and phloem bundles, and lignin modification/reduction. There was depletion of the principal phenolics concomitant with massive accumulation of novel metabolites, including the glucosides and glucose esters of 4-hydroxybenzoic acid and vanillic acid and the glucosides of 4-hydroxybenzyl alcohol and vanillyl alcohol. HCHL plants exhibited increased accumulation of transcripts for phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, and 4-coumarate:CoA ligase, whereas beta-1,3-glucanase was suppressed. This study, exploiting the ability of a bacterial gene to divert plant secondary metabolism, provides insight into how plants modify inappropriately accumulated metabolites and reveals the consequences of depleting the major phenolic pools.

Physicochemical studies of caroubin: a gluten-like protein

It has been reported that caroubin, a protein mixture obtained from carob seeds, has rheological properties similar to those of gluten. Comparative studies of the effects of hydration and temperature on caroubin and gluten were carried out with the aid of NMR, FTIR, scanning electron microscopy, and differential scanning calorimetry techniques. The results show that caroubin has a more ordered structure than gluten and that hydration has little effect on its secondary structure when compared to gluten. Caroubin is more easily accessible to water than gluten, suggesting that caroubin is more hydrophilic in nature. On hydration, caroubin, like gluten, forms fibrillar structures and sheets.

Fracture mechanics of the cell wall of Chara corallina

Previous mechanical studies using algae have concentrated on cell extension and growth using creep-type experiments, but there appears to be no published study of their failure properties. The mechanical strength of single large internode cell walls (up to 2 mm diameter and 100 mm in length) of the charophyte (giant alga) Chara corallina was determined by dissecting cells to give sheets of cell wall, which were then notched and fractured under tension. Tensile tests, using a range of notch sizes, were conducted on cell walls of varying age and maturity to establish their notch sensitivity and to investigate the propagation of cracks in plant cell walls. The thickness and stiffness of the walls increased with age whereas their strength was little affected. The strength of unnotched walls was estimated as 47+/-13 MPa, comparable to that of some grasses but an order of magnitude higher than that published for model bacterial cellulose composite walls. The strength was notch-sensitive and the critical stress intensity factor K1c was estimated to be 0.63+/-0.19 MNm(-3/2), comparable to published values for grasses.

Esterified phenolics of the cell walls of chufa (Cyperus esculentusL. ) tubers and their role in texture

Chufas (Cyperus esculentus) are edible tubers that, like Chinese waterchestnut (CWC), are very crisp when raw and do not soften when cooked. The present study compares the mechanical properties of chufas with those of potato and CWC in relation to the carbohydrate and phenolic compositions of the cell walls. The cutting toughness of raw chufa was higher than that of raw CWC and potato; its value decreased on boiling, as also observed with CWC, but remained over twice that of raw potato. Chufa cell walls were rich in xylose, arabinose, glucose, uronic acid, and galactose, with minor quantities of mannose. The cell walls of the parenchyma exhibited a uniform pH-dependent autofluorescence indicating the presence of cinnamic acid derivatives. Analysis of these revealed that peeled tuber cell walls are rich in ferulic acid, whereas p-coumaric acid dominates the monomeric phenol fraction of the skin. Cell wall material from both skin and peeled tubers contains a significant amount of different diferulic acids ( approximately 20% of the wall ferulic acid), consisting mainly of the 8-O-4'-, 8-5'-, and 5-5'-dimers. These are potentially available to form thermally stable cross-links between polysaccharides within the wall and between cells. This may confer thermal stability of texture.

Physicochemical characteristics of onion (Allium cepa L.) tissues

The structure and mechanical properties of onions are important factors affecting their textural quality. The onion bulb consists of several layers of pigmented, papery scales surrounding fleshy storage scales that comprise an upper epidermis, an intermediate parenchyma tissue, and a lower epidermis. The purpose of this study was to examine the chemical composition of cell walls from the papery scales and outer fleshy scales of onion (Allium cepa L. cv. Sturon) in relation to their mechanical properties. Cell-wall material (CWM) was prepared from the component tissues and analyzed for its carbohydrate and phenolic composition. The CWMs were rich in uronic acid and glucose, with smaller quantities of arabinose, galactose, and xylose. In the fleshy scales, the lower epidermis contained relatively more galactose-rich pectic polysaccharides, whereas the upper epidermis and the papery scales contained virtually no galactose. Analysis of mechanical properties showed that the order of strength of the tissues was papery scales > fleshy scales, which were in the order lower epidermis > upper epidermis > intermediate parenchyma. The upper epidermis of fleshy scales was stronger in the vertical than the horizontal direction, and both orientations showed negligible notch sensitivity. Cyclohexane-trans-1,2-diaminetetraacetate-induced vortex-induced cell separation of the intermediate layer of fleshy scales indicated that calcium cross-linking may play an important role in cell-cell adhesion. A small but significant amount of ferulic acid was found in the walls, predominantly in the thick cuticle of the lower epidermis of fleshy scales. Alkali-labile wall-bound flavonoids were also detected.

Differential toxicities of organophosphate and carbamate insecticides in the nestling European starling (Sturnus vulgaris)

The concept of B-esterase buffering against anti-cholinesterase (ChE) insecticide toxicity has been extensively researched in mammalian species. Presumably due to relatively low levels of anti-ChE detoxifying enzyme activity in birds, however, avian species are often more susceptible to the toxic effects of these compounds. We quantified B-esterase buffering of organophosphate (diazinon and methyl parathion) and carbamate (aldicarb and oxamyl) toxicity in nestling European starlings (Sturnus vulgaris). The differential toxicities were studied using mortality, behavioral observation, and inhibitor affinity data. The toxicities of diazinon, methyl parathion, and oxamyl were affected by the removal of butyrylcholinesterase (BChE) using the specific inhibitor tetraisopropylpyrophosphoramide (iso-OMPA). When BChE was absent, aldicarb toxicity was not affected. Theoretically, compounds affected by BChE removal would have a higher affinity for BChE or carboxylesterase (CaE) than acetylcholinesterase (AChE). However, this was only the case for diazoxon, which had a 1,000-fold higher affinity for plasma BChE and CaE than AChE. Methyl paraoxon and aldicarb had a higher affinity for plasma AChE than for BChE or CaE. Oxamyl had similar IC50 values for all three enzymes studied. The generation of IC50 curves for each inhibitor revealed the presence of nonsensitive forms of CaE in both the plasma and brain. Based on the results of this research, there appears to be no strict correlation between mortality data and inhibitor affinities for each esterase that alone can explain the differential toxicities of these compounds.

Modifications to physicochemical and nutritional properties of hard-To-cook beans (Phaseolus vulgaris L.) by extrusion cooking

The objective of this work was to evaluate extrusion cooking as a means to improve the nutritional properties of Phaseolus vulgaris L. that had been stored either at 42 degrees C and 80% relative humidity for 6 weeks or for periods >1 year in cereal stores in tropical conditions. Storage under these conditions resulted in an increase in cooking time increased (7.7- and 12-fold, respectively) as a result of development of the hard-to-cook (HTC) defect. Single-screw extrusion of the milled beans was carried out at four barrel temperatures and two moisture contents. The extrudate bulk density and water solubility index decreased with increasing temperature, whereas the water absorption index increased due to the higher proportion of gelatinized starch in the extruded samples. Both fresh and HTC beans contained nutritionally significant amounts of lectins, trypsin, and alpha-amylase inhibitors, which were mostly inactivated by extrusion. Extrusion also caused a considerable redistribution of insoluble dietary fiber to soluble, although the total dietary fiber content was not affected. Changes in solubility involved pectic polysaccharides, arabinose and uronic acids being the main sugars involved. Stored beans subjected to extrusion cooking showed physical and chemical characteristics similar to those of extrudates from fresh beans.

Are we making progress with emergency contraception? Recent findings on American adults and health professionals

OBJECTIVES

To determine how awareness of and practices and attitudes toward emergency contraceptive pills (ECPs) have progressed among the American public and US health professionals.

METHODS

In 1997, we conducted two nationally representative telephone surveys of Americans and health professionals of their knowledge, attitudes, and practices on ECPs and compared the findings to previous surveys.

RESULTS

66% of women and 51% of men 18 to 44 years old had heard of ECPs, up from 61% of women and 45% of men the same age in 1994. Only 1% of women surveyed reported having ever used this method, reflecting no change from 1994. Only 11% of women knew enough about ECPs to be able to use them. Americans named media as the primary source of information about ECPs. The proportion of physicians who had prescribed ECPs at least once in the preceding year increased significantly in 1997: 85% of obstetrician/gynecologists and 50% of family physicians compared to 69% and 34% in 1995. Almost all health professionals considered ECPs to be safe (99%) and effective (100%), yet relatively few discussed this option with their patients, and even fewer commonly prescribed it.

CONCLUSION

Ongoing efforts are needed to improve awareness among the general public and to encourage health professionals to discuss and offer ECPs more widely.

Low pH enhances the transfer of carotene from carrot juice to olive oil

A current model for carotenoid transport and absorption in the gut proposes an initial solubilization in the oil phase of dietary emulsions followed by incorporation of the carotenoids in mixed bile salt micelles. To assess the relevance of the first stage of this model to what is observed in vivo we have examined the transfer of carotene from carrot juice to olive oil. Increased acidity enhanced the transfer from both whole juice and carotene crystals isolated from carrot chromoplasts. The transfer was significantly slower from whole juice. By using exogenous beta-carotene and measuring its transfer to oil in the presence and absence of carrot juice we have demonstrated that the inhibition of the transfer in juice arises, at least in part, from soluble juice factors. The inhibition is relieved by a fall in pH, which leads to lowering of the electric potential at the oil/aqueous phase interface and aggregation of carrot tissue including crystalline carotene. Under conditions of low pH, oil droplets adhere to the tissue aggregates, allowing carotene to pass into the oil. Our results provide an explanation for why carotene absorption in vivo is depressed by conditions of low gastric acidity.

Missed opportunities: teenagers and emergency contraception

OBJECTIVE

To determine American teenagers' awareness of and knowledge about emergency contraceptive pills and their likelihood to use them.

METHODS

We conducted a nationally representative telephone survey between March 28, 1996, and May 5, 1996, of 1510 teenagers (757 girls and 753 boys), aged 12 to 18 years, living in the continental United States in households with telephones. The sample overrepresented African American, Latino, and low-income teenagers. The error attributable to sampling and other random effects for the total sample is +/-3 percentage points at the 95% confidence level.

RESULTS

Of the 1510 teenagers, only about one quarter (23%) were aware that "anything" could be done after unprotected sex to prevent pregnancy. Slightly more (28%) had heard of "morning-after pills" or emergency contraceptive pills. Of the 423 teenagers who had heard of emergency contraceptive pills, one third (32%) did not know that a prescription is necessary to obtain them, and three quarters (78%) underestimated how long after unprotected intercourse the emergency contraceptive pill regimen could be initiated. Only 9% knew that emergency contraceptive pills are effective as long as 72 hours after unprotected sex. After being told about the option of emergency contraceptive pills, two thirds (67%) of teenaged girls said that they would be likely to use emergency contraceptive pills. Among the 66% of teenaged girls who had not previously heard of emergency contraceptive pills, 64% said that they would be likely to use them.

CONCLUSIONS

Emergency contraceptive pills have great potential as a tool for reducing unplanned pregnancies among teenaged girls in the United States. Few teenaged girls were aware that this option exists. Once informed, teenaged girls reported being very interested in taking emergency contraceptive pills if needed.

Interplanting Wheat Is Not an Effective Postplant Management Tactic for Criconemella xenoplax in Peach Production

In two orchard experiments, interplanting wheat (Triticum aestivum cv. Stacy) around either newly planted or 4-year-old well-established peach trees did not suppress (P ≤ 0.05) the population density of the ring nematode, Criconemella xenoplax, after 3 years. Furthermore, inter-planting wheat around newly planted trees reduced tree growth, perhaps the result of competition for water and (or) nutrients. Wheat root exudate was not as attractive to C. xenoplax as peach root exudate, but wheat root exudate did not repel the nematode either. Stacy wheat appeared to be more beneficial as a preplant rather than as a postplant ground cover management tool for suppressing the population density of C. xenoplax.

The microstructure and distribution of micro-organisms within mature Serra cheese

The distribution of micro-organisms in mature Serra, a traditional Portuguese cheese made from unpasteurised ewes' milk without added starter culture, was examined by light microscopy and electron microscopy. Four populations of micro-organisms were recognized according to their position within the cheese: (i) those present as apparently axenic colonies within the curd matrix; (ii) bacteria growing along curd junctions; (iii) yeasts and bacteria present in the smear on the surface of the cheese and (iv) bacteria found in cracks which penetrated the outer part of the cheese from the rind. Two types of crystals were observed, together with contaminants of vegetable origin and somatic cells originating from the milk.

Atomic Force Microscopy of Interfacial Protein Films

Atomic force microscopy (AFM) has been used to image interfacial films of bovine serum albumen and beta-casein produced at hexadecane/water and air/water interfaces, respectively. Planar oil/water and air/water interfaces have been used to model protein films such as may form in emulsions and foams. The protein films were picked up onto mica sheets and imaged under butanol. Both systems studied yielded homogeneous flat networks which could be imaged at molecular resolution and which demonstrate the potential for using AFM to probe interfacial networks.

Growth of food-borne pathogenic bacteria in oil-in-water emulsions: I--Methods for investigating the form of growth

Methods are presented for investigating the site and form of growth of bacteria in model oil-in-water emulsions and in dairy cream. Following growth of the bacteria, the continuous aqueous phase is gelled using agarose and the oil phase removed using a mixture of chloroform and methanol. Using this method, the authors have found that Listeria monocytogenes, Salmonella typhimurium and Yersinia enterocolitica grow in the form of colonies in concentrated oil-in-water emulsions. Colonies of L. monocytogenes and Y. enterocolitica also form in artificially-inoculated fresh and tinned dairy cream. If information about the precise site of growth is not required, the authors have discovered that intact colonies can be liberated from the model emulsions by dissolving away the oil phase with chloroform:methanol.

Growth of food-borne pathogenic bacteria in oil-in-water emulsions: II--Effect of emulsion structure on growth parameters and form of growth

The growth rates and yields of Listeria monocytogenes and Yersinia enterocolitica were determined in liquid culture media, and in model oil-in-water emulsions that contained 30, 70 or 83% (v/v) hexadecane. In emulsions with a mean droplet size of 2 microns containing 83% (v/v) hexadecane, the growth of both organisms resulted in decreased yields. Additionally, in these emulsions adjusted to pH 5.0 or 4.4 the growth rate of L. monocytogenes was significantly less than in other model systems which had an aqueous phase of equivalent chemical composition. Microscopic examination of the 83% (v/v) emulsion showed that its microstructure immobilized the bacteria, which were constrained to grow as colonies. Bacteria behaved similarly in model emulsions of either hexadecane or sunflower oil. Manipulation of the droplet size distribution of the emulsions changed the form and rate of growth of bacteria within them.

RNA sequence variants in live poliovirus vaccine and their relation to neurovirulence

Mutant analysis by polymerase chain reaction and restriction enzyme cleavage (MAPREC) was used to study sequence heterogeneity and stability in attenuated poliovirus type 3 at positions in which the vaccine virus differs from its wild-type progenitor. Of seven genomic positions tested, only two (positions 472 and 2493) show nucleotide heterogeneity. Propagation of the vaccine virus in cell cultures leads to rapid selection of virus with reversions at these two positions of the genome. The relative abundance of reversions at position 472 correlates with the results of monkey neurovirulence tests, while the mutation at position 2493 is not directly associated with neurovirulence of the virus in monkeys. Instead, the abundance of mutations at the latter position correlates with the source of the seed virus and its passage level. These results further indicate that MAPREC at position 472 can be used to assess the quality of poliovirus type 3 vaccine.

Urine metabolite values in fed and nonfed clinically normal beagles

Twenty-four-hour excretion of urine metabolites was determined in 33 clinically normal Beagles during periods of consumption of a standard diet and when food was withheld. The goal was to determine normal canine values for urine analytes incriminated in the genesis of calcium oxalate uroliths. During periods when dogs consumed food, dairy urinary excretion of calcium, uric acid, sodium, potassium, magnesium, ammonium, and hydrogen ions were significantly (P = 0.0004, 0.0038, 0.001, 0.0001, 0.0004, 0.0001, and 0.024, respectively) higher than when food was withheld. Urinary excretion of phosphorus, oxalate, and citrate were not significantly different between samples obtained during periods of food consumption and when food was withheld. Male dogs excreted significantly higher quantities of urine oxalate than females during fed (P = 0.003) and nonfed (P = 0.003) conditions. When food was withheld, urinary uric acid excretion was significantly higher in males than females (P = 0.01). Females excreted significantly more urine calcium than males when food was withheld (P = 0.003). Our results indicated that dietary conditions influence the quantity of sodium, potassium, calcium, magnesium, and uric acid excreted in the urine of clinically normal dogs; therefore, dietary conditions should be considered when measuring the concentration of these analytes in urine.

Aqueous dissolution of crystalline and amorphous amylose-alcohol complexes

Complexes of amylose, the linear starch polysaccharide, with linear alcohols having chain lengths varying from 4 to 8 carbon atoms, were prepared. Either crystalline or amorphous complexes could be formed depending on preparation conditions. Crystalline complexes gave sharp X-ray diffraction patterns, characteristic of the VH form of amylose, whereas no observable pattern was obtained from the amorphous form. Thermal dissociation of the complexes occurred at increasing temperatures with increasing alcohol chain length. Crystalline complexes dissociated at temperatures approximately 23 degrees C higher than their amorphous counterparts and the enthalpy of dissociation was also greater for the crystalline samples. Enthalpy values were independent of alcohol chain length. Differences in thermal behaviour of the two types of complex may be described in terms of the polymer crystal lattice energy and may explain the variability of reported results for complex dissociation in the literature.

The Saccharomyces cerevisiae BAR1 gene encodes an exported protein with homology to pepsin

Saccharomyces cerevisiae a cells secrete an extracellular protein, called "barrier" activity, that acts as an antagonist of alpha factor, the peptide mating pheromone produced by mating-type alpha cells. We report here the DNA sequence of BAR1, the structural gene for barrier activity. The deduced primary translation product of 587 amino acids has a putative signal peptide, nine potential asparagine-linked glycosylation sites, and marked sequence similarity of the first two-thirds of the protein with pepsin-like proteases. Barrier activity was abolished by in vitro mutation of an aspartic acid predicted from this sequence homology to be in the active site. Therefore, barrier protein is probably a protease that cleaves alpha factor. The sequence similarity suggests that the first two-thirds of the barrier protein is organized into two distinct structural domains like those of the pepsin-like proteases. However, the BAR1 gene product has a third carboxyl-terminal domain of unknown function; deletion of at least 166 of the 191 amino acids of this region has no significant effect on barrier activity.

Genetic control of capsid length in bacteriophage T4: DNA sequence analysis of petite and petite/giant mutants

The T4 gene 23 product (gp23) encodes the major structural protein of the mature capsid. Mutations in this gene have been described which disrupt the normal length-determining mechanism (A.H. Doermann, F.A. Eiserling, and L. Boehner, J. Virol. 12:374-385, 1973). Mutants which produce high levels of petite and giant phage (ptg) are restricted to three tight clusters in gene 23 (A.H. Doermann, A. Pao, and P. Jackson, J. Virol. 61:2823-2827, 1987). Twenty-six of these ptg mutations were cloned, and their DNA sequence alterations were determined. Each member of this set of ptg mutants arose from a single mutation, and the set defined 10 different sites at which ptg mutations can occur in gene 23. Two petite (pt) mutations in gene 23 (pt21-34 and ptE920g), which produce high frequencies of petite particles but no giants, were also sequenced. Both pt21-34 and ptE920g were shown to include multiple mutations. The phenotypes attributed to both pt and ptg mutations are discussed relative to the mechanism of capsid morphogenesis. A site-directed mutation (SD-1E) was created at the ptgNg191 site, and its phenotypic consequences were examined. Plaque morphology revertants arising from a gene 23 mutant derivative of pt21-34 and from SD-1E were isolated. A preliminary mapping of the mutation(s) responsible for their revertant phenotypes suggested that both intra- and extragenic suppressors of the petite phenotype can be isolated by this method.

Characterization of two chlorophyll b-deficient, azide-derived mutants of Hordeum vulgare cv. Maris Mink

Two mutant lines of Hordeum vulgare cv. Maris Mink (designated RChl 46 and 47) deficient in chlorophyll b have been isolated following azide mutagenesis. Two major thylakoid membrane proteins of molecular weight 25 and 26 k daltons are absent from the mutant plants following analysis by SDS gel electrophoresis, presumably due to a lack of the light harvesting chlorophyll a/b complex. The photosynthetic capabilities of the wild type and mutant lines were very similar.

Nucleotide sequence and transcriptional initiation site of two Pseudomonas aeruginosa pilin genes

The complete nucleotide sequences of the 1.2-kilobase HindIII fragments which contain the pilin genes of two independently isolated strains of Pseudomonas aeruginosa (PAK and PA103) have been determined and compared to that of strain PA01 (Sastry, P. A., Finlay, B. B., Pasloske, B. L., Paranchych, W., Pearlstone, J. R., and Smollier, L. B. (1985) J. Bacteriol. 164, 571-577). The fragments share extensive regions of homology, including the 5'- and 3'-flanking sequences as well as the 5' end of the pilin gene. The most highly diverged segments of the pilin genes are those which encode the variable carboxyl-terminal region of the pilin polypeptides. The pilin polypeptides each contain a 6-amino acid amino-terminal leader peptide (Met-Lys-Ala-Gln-Lys-Gly) and are nearly identical in the following 60 amino acids. The carboxyl-terminal portion of the pilin polypeptides contain extensive regions of divergence in their amino acid sequences, although hydropathicity analysis of the pilin polypeptides indicated that they are structurally similar. The transcriptional initiation site of the PAK pilin gene has been determined by S1 nuclease mapping. The promoter region at -10 and -35 base pairs from the transcriptional initiation site shows no significant homology to the consensus Escherichia coli promoter, but the -12 and -24 regions show a high degree of homology to promoters which require the ntrA gene product for transcription. Several other Pseudomonas promoters and the promoters of the homologous pilin genes from other bacterial species also share homology to this sequence.

Nucleotide sequence of the triosephosphate isomerase gene from Aspergillus nidulans: implications for a differential loss of introns

A functional cDNA from Aspergillus nidulans encoding triosephosphate isomerase (TPI) was isolated by its ability to complement a tpi1 mutation in Saccharomyces cerevisiae. This cDNA was used to obtain the corresponding gene, tpiA. Alignment of the cDNA and genomic DNA nucleotide sequences indicated that tpiA contains five introns. The intron positions in the tpiA gene were compared with those in the TPI genes of human, chicken, and maize. One intron is present at an identical position in all four organisms, two other introns are located in similar positions in A. nidulans and maize, and the remaining two introns are unique to A. nidulans. These Aspergillus-specific introns are located in regions of the protein that were predicted to be interrupted by introns based on analysis of a Go plot of chicken TPI. These comparisons are discussed in relation to the evolution of introns within TPI genes.

Nucleotide sequence of bacteriophage T4 gene 23 and the amino acid sequence of its product

We have determined the nucleotide sequence of gene 23 of bacteriophage T4 by the methods of Maxam and Gilbert and of Sanger. The identities of approximately 80% of the amino acid residues of the major capsid protein which is encoded by gene 23 were determined additionally by Edman degradation of the intact protein and its peptides. Fifteen gene 23 amber mutation sites have been located within the sequence, and the 3' transcription termination site for genes 21, 22 and 23 has been identified.

Ultrastructure of the mesophyll cells of leaves of a catalase-deficient mutant of barley (Hordeum vulgare L.)

The ultrastructure of mesophyll cells from leaves of a catalase-deficient homozygous mutant of barley (RPr 79/4), which grows poorly in air but normally in carbon-dioxide-enriched air, has been examined and compared with that of the cultivar Maris Mink with normal catalase levels, and with that of the F1 progeny of the cross RPr 79/4xGolden Promise with 50% normal catalase levels. In Maris Mink, the F1 progeny, and the mutant in which photorespiration had been suppressed by growing in air enriched to 0.2% CO2, the ultrastructure of the mesophyll cells was typical of young festucoid leaves with the peroxisomes containing thread-like inclusions. In air-grown leaves of the mutant RPr 79/4 which had developed lesions and become shrivelled, all the chloroplasts were irregular in outline, and in some the granal membranes were disrupted into abnormal honeycomb configurations and the plastid envelope was absent. In necrotic tissue, membrane fragments and osmiophilic droplets marked the sites of severely damaged chloroplasts. The peroxisomes contained diffuse tufts of electron-opaque material as well as fibrous strands. Catalase activity, visualised cytochemically by DAB, was located exclusively in the peroxisomes of Maris Mink and the F1 progeny, but none was found in the mutant grown either in CO2-rich air, or in normal air. The role of catalase in preventing ultrastructural damage by hydrogen peroxide during photorespiration is discussed.

Prevaccination screening of medical and dental students. Should low levels of antibody to hepatitis B surface antigen preclude vaccination?

The prevalence of hepatitis B virus (HBV) markers in 484 medical and 329 dental students was studied. Three students (0.9%) were hepatitis B surface antigen (HBsAg) reactive, and 46 students (5.7%) were reactive for antibody to HBsAg (anti-HBs). There was no difference in anti-HBs frequency between medical and dental students, and the prevalence of this marker was not associated with year in school. Of the 46 reactors, eight (17%) were nonreproducible and 38 (83%) were reproducibly reactive when the same samples were reanalyzed. Of note, all nonreproducible reactors exhibited anti-HBs sample-negative control (S/N) ratios of less than 10, and none were positive for antibody to hepatitis B core antigen (anti-HBc). Nineteen (50%) of the reproducible reactors had anti-HBs S/N ratios equal to or greater than 10, and only 15 (39%) were anti-HBc positive. In view of these observations, we do not recommend HBV screening in a vaccine program for health students. Due to the frequency with which low-level anti-HBs reactors without anti-HBc are found to be nonreproducibly positive, we are concerned by the potential overinterpretation of such results before the formulation of decisions about the need for vaccination.