Hybrid insulin peptide isomers spontaneously form in pancreatic beta-cells from an aspartic anhydride intermediate

Hybrid insulin peptides (HIPs) form in beta-cells when insulin fragments link to other peptides through a peptide bond. HIPs contain nongenomic amino acid sequences and have been identified as targets for autoreactive T cells in type 1 diabetes. A subgroup of HIPs, in which N-terminal amine groups of various peptides are linked to aspartic acid residues of insulin C-peptide, was detected through mass spectrometry in pancreatic islets. Here, we investigate a novel mechanism that leads to the formation of these HIPs in human and murine islets. Our research herein shows that these HIPs form spontaneously in beta-cells through a mechanism involving an aspartic anhydride intermediate. This mechanism leads to the formation of a regular HIP containing a standard peptide bond as well as a HIP-isomer containing an isopeptide bond by linkage to the carboxylic acid side chain of the aspartic acid residue. We used mass spectrometric analyses to confirm the presence of both HIP isomers in islets, thereby validating the occurrence of this novel reaction mechanism in beta-cells. The spontaneous formation of new peptide bonds within cells may lead to the development of neoepitopes that contribute to the pathogenesis of type 1 diabetes as well as other autoimmune diseases.

Early and late preterm birth rates in participants adherent to randomly assigned high dose docosahexaenoic acid (DHA) supplementation in pregnancy

BACKGROUND

Intention-to-treat analyses do not address adherence. Per protocol analyses treat nonadherence as a protocol deviation and assess if the intervention is effective if followed.

OBJECTIVE

To determine the rate of early preterm birth (EPTB, <34 weeks gestation) and preterm birth (PTB, <37 weeks gestation) in participants who adhered to a randomly assigned docosahexaenoic acid (DHA) dose of 1000 mg/day.

STUDY DESIGN

Eleven hundred women with a singleton pregnancy were enrolled before 20-weeks' gestation, provided a capsule with 200 mg/day DHA and randomly assigned to two additional capsules containing a placebo or 800 mg of DHA. In the Bayesian Adaptive Design, new randomization schedules were determined at prespecified intervals. In each randomization, the group with the most EPTB was assigned fewer participants than the other group. Adherence was defined a priori as a postpartum red blood cell phospholipid DHA (RBC-PL-DHA) ≥5.5%.and post hoc as ≥8.0% RBC-PL-DHA, the latter after examination of postpartum RBC-PL-DHA. Bayesian mixture models were fitted for gestational age and dichotomized for EPTB and PTB as a function of baseline RBC-PL-DHA and dose-adherence. Bayesian hierarchical models were also fitted for EPTB by dose adherence and quartiles of baseline RBC-PL-DHA.

RESULTS

Adherence to the high dose using both RBC-PL-DHA cut points resulted in less EPTB compared to 200 mg [Bayesian posterior probability (pp) = 0.93 and 0.92, respectively]. For participants in the two lowest quartiles of baseline DHA status, adherence to the higher dose resulted in lower EPTB (≥5.5% RBC-PL-DHA, quartiles 1 and 2, pp = 0.95 and 0.96; ≥8% RBC-PL-DHA, quartiles 1 and 2, pp = 0.94 and 0.95). Using the Bayesian model, EPTB was reduced by 65%, from 3.45% to 1.2%, using both cut points. Adherence also reduced PTB before 35, 36 and 37 weeks using both cut points (pp ≥ 0.95). In general, performance of the nonadherent subgroup mirrored that of participants assigned to 200 mg.

CONCLUSION

Adherence to high dose DHA reduced EPTB and PTB. The largest effect of adherence on reducing EPTB was observed in women with low baseline DHA levels.

CLINICALTRIALS

gov (NCT02626299).

Docosahexaenoic acid (DHA) intake estimated from a 7-question survey identifies pregnancies most likely to benefit from high-dose DHA supplementation

BACKGROUND

Two randomized trials found women with low blood docosahexaenoic acid (DHA; an omega 3 fatty acid) had fewer early preterm births (<34 weeks gestation) if they were assigned to high dose DHA supplementation, however, there is currently no capacity for clinicians who care for pregnancies to obtain a blood assessment of DHA. Determining a way to identify women with low DHA intake whose risk could be lowered by high dose DHA supplementation is desired.

OBJECTIVE

To determine if assessing DHA intake can identify pregnancies that benefit from high dose DHA supplementation.

STUDY DESIGN

This secondary analysis used birth data from 1310 pregnant women who completed a 7-question food frequency questionnaire (DHA-FFQ) at 16.8 ± 2.5 weeks gestation that is validated to assess DHA status. They were then randomly assigned to a standard (200 mg/day) or high dose (800 or 1000 mg/day) DHA supplement for the remainder of pregnancy. Bayesian logistic regressions were fitted for early preterm birth and preterm birth as a function of DHA intake and assigned DHA dose.

RESULTS

Participants who consumed less than 150 mg/day DHA prior to 20 weeks' gestation (n = 810/1310, 58.1%) had a lower Bayesian posterior probability (pp) of early preterm birth if they were assigned to high dose DHA supplementation (1.4% vs 3.9%, pp = 0.99). The effect on preterm birth (<37 weeks) was also significant (11.3% vs 14.8%, pp = 0.97).

CONCLUSION

The DHA-FFQ can identify pregnancies that will benefit most from high dose DHA supplementation and reduce the risk of preterm birth. The DHA-FFQ is low burden to providers and patients and could be easily implemented in obstetrical practice.

Cathepsin D Drives the Formation of Hybrid Insulin Peptides Relevant to the Pathogenesis of Type 1 Diabetes

Hybrid insulin peptides (HIPs) form in pancreatic β-cells through the formation of peptide bonds between proinsulin fragments and other peptides. HIPs have been identified in pancreatic islets by mass spectrometry and are targeted by CD4 T cells in patients with type 1 diabetes (T1D) as well as by pathogenic CD4 T-cell clones in nonobese diabetic (NOD) mice. The mechanism of HIP formation is currently poorly understood; however, it is well established that proteases can drive the formation of new peptide bonds in a side reaction during peptide bond hydrolysis. Here, we used a proteomic strategy on enriched insulin granules and identified cathepsin D (CatD) as the primary protease driving the specific formation of HIPs targeted by disease-relevant CD4 T cells in T1D. We also established that NOD islets deficient in cathepsin L (CatL), another protease implicated in the formation of disease-relevant HIPs, contain elevated levels of HIPs, indicating a role for CatL in the proteolytic degradation of HIPs. In summary, our data suggest that CatD may be a therapeutic target in efforts to prevent or slow the autoimmune destruction of β-cells mediated by HIP-reactive CD4 T cells in T1D.

Utility of a 7- question online screener for DHA intake

The secondary analyses of two large, recently completed randomized clinical trials of DHA supplementation in pregnancy found that women with a low baseline DHA status benefited from randomization to a higher dose (800 vs 0 and 1000 vs 200 mg/day DHA). To obtain DHA status, it is necessary to obtain a blood sample and conduct an analysis using gas chromatography (GC) or GC-mass spectrometry (GCMS), both barriers to clinics where pregnant women receive advice on nutrition. Participants consuming less than 150 mg/day of DHA at baseline in our recent trial had a lower risk of early preterm birth and preterm birth when assigned to 1000 vs 200 m/day DHA. DHA intake was determined using a 7-question food frequency questionnaire administered by a trained nutritionist. Because the need for trained personnel to administer the questionnaire would be a barrier to implementing this finding in clinical management of pregnancy, the goal of this study was to determine if an online version of the questionnaire could be validly completed without assistance.

Validation of an abbreviated food frequency questionnaire for estimating DHA intake of pregnant women in the United States

Docosahexaenoic acid (DHA) intake was estimated in pregnant women between 12- and 20-weeks' gestation using the National Cancer Institute's (NCI) Diet History Questionnaire-II (DHQ-II) and a 7-question screener designed to capture DHA intake (DHA Food Frequency Questionnaire, DHA-FFQ). Results from both methods were compared to red blood cell phospholipid DHA (RBC-DHA) weight percent of total fatty acids. DHA intake from the DHA-FFQ was more highly correlated with RBC-DHA (r_s=0.528) than the DHQ-II (r_s=0.352). Moreover, the DHA-FFQ allowed us to obtain reliable intake data from 1355 of 1400 participants. The DHQ-II provided reliable intake for only 847 of 1400, because many participants only partially completed it and it was not validated for Hispanic participants. Maternal age, parity, and socioeconomic status (SES) were also significant predictors of RBC-DHA. When included with estimated intake from the DHA-FFQ, the model accounted for 36% of the variation in RBC-DHA.

Structural implications of fenestrated stent graft misalignment

BACKGROUND

Endovascular aneurysm repair is a minimally-invasive method for the treatment of abdominal aortic aneurysms. For aneurysms that involve the visceral arteries, a custom-made stent graft with fenestrations for the branch arteries is required. The purpose of the current study is to evaluate the structural impact of misaligned fenestrations with respect to luminal patency and proximal aortic neck apposition in an in vitro model.

METHODS

A custom apparatus was used to evaluate seven Anaconda and three Zenith fenestrated stent grafts. All stent grafts were evaluated at 10° increments of stent/fenestration misalignment up to 80°. Images were captured at each interval and the luminal cross-sectional area and wall apposition were measured.

RESULTS

The Anaconda stent graft, which has an unsupported main body, demonstrated a linear reduction in luminal patency at increasing angles of misalignment (P < 0.0001). Stent/fenestration misalignments of 20° and 80° resulted in decreases in mean luminal patency of 14% and 54% respectively. The Zenith stent graft demonstrated a similar decrease in luminal patency, starting at misalignments of ≥40° (P < 0.0001). However, with stent/fenestration misalignments of ≥30°, apposition between the Zenith stent graft and the simulated aortic neck was compromised suggesting the creation of a type Ia endoleak.

CONCLUSIONS

Both the Anaconda and Zenith devices behave adversely at extreme angles of misalignment with luminal narrowing in the Anaconda device and loss of wall apposition in the Zenith device; however, both stent grafts appear to be equivalent at low angles of misalignment.

Naturally occurring R225W mutation of the gene encoding AMP-activated protein kinase (AMPK)gamma(3) results in increased oxidative capacity and glucose uptake in human primary myotubes

AIMS/HYPOTHESIS

AMP-activated protein kinase (AMPK) has a broad role in the regulation of glucose and lipid metabolism making it a promising target in the treatment of type 2 diabetes mellitus. We therefore sought to characterise for the first time the effects of chronic AMPK activation on skeletal muscle carbohydrate metabolism in carriers of the rare gain-of-function mutation of the gene encoding AMPKgamma(3) subunit, PRKAG3 R225W.

METHODS

Aspects of fuel metabolism were studied in vitro in myocytes isolated from vastus lateralis of PRKAG3 R225W carriers and matched control participants. In vivo, muscular strength and fatigue were evaluated by isokinetic dynamometer and surface electromyography, respectively. Glucose uptake in exercising quadriceps was determined using [(18)F]fluorodeoxyglucose and positron emission tomography.

RESULTS

Myotubes from PRKAG3 R225W carriers had threefold higher mitochondrial content (p < 0.01) and oxidative capacity, higher leak-dependent respiration (1.6-fold, p < 0.05), higher basal glucose uptake (twofold, p < 0.01) and higher glycogen synthesis rates (twofold, p < 0.05) than control myotubes. They also had higher levels of intracellular glycogen (p < 0.01) and a trend for lower intramuscular triacylglycerol stores. R225W carriers showed remarkable resistance to muscular fatigue and a trend for increased glucose uptake in exercising muscle in vivo.

CONCLUSIONS/INTERPRETATION

Through the enhancement of skeletal muscle glucose uptake and increased mitochondrial content, the R225W mutation may significantly enhance exercise performance. These findings are also consistent with the hypothesis that the gamma(3) subunit of AMPK is a promising tissue-specific target for the treatment of type 2 diabetes mellitus, a condition in which glucose uptake and mitochondrial function are impaired.

Increased susceptibility to oxidative damage in post-diabetic human myotubes

AIMS/HYPOTHESIS

Obesity is an important risk factor for the development of type 2 diabetes, but not all obese individuals develop this complication. The clinical signs of type 2 diabetes can often be reversed with weight loss; however, it is unknown whether the skeletal muscle oxidative stress associated with type 2 diabetes remains after weight loss. We hypothesised that chronic exposure to high glucose and insulin would re-elicit impaired metabolism in primary myotubes from patients with a history of type 2 diabetes.

METHODS

Obese participants with or without type 2 diabetes completed a standardised weight loss protocol, following which all participants were euglycaemic and had similar indices of insulin sensitivity. Satellite cells were isolated from muscle biopsies and differentiated under low or high glucose and insulin conditions (HGI).

RESULTS

Cells from participants with no history of type 2 diabetes showed robust increases in mitochondrial content, citrate synthase and cytochrome c oxidase activities when exposed to HGI. This increase in oxidative capacity was absent in cells from patients with a history of type 2 diabetes. High glucose and insulin caused increased oxidative damage in cells from the latter, despite higher superoxide dismutase expression. Cells from patients with a history of type 2 diabetes were unable to decrease mitochondrial membrane potential in response to HGI, potentially due to lower levels of uncoupling protein-3.

CONCLUSIONS/INTERPRETATION

This is the first report to note that primary myotubes from patients with a history of type 2 diabetes are unable to adapt to a hyperglycaemic-hyperinsulinaemic challenge. We have demonstrated that impaired mitochondrial biogenesis and an inability to manage oxidative stress define a muscle phenotype at risk of obesity-associated type 2 diabetes.

Interface pressure measurements: Visual interpretation of pressure maps with MS clients

PURPOSE

Pressure mapping systems provide useful information for pressure care assessment. Healthcare professionals tend to rely upon their colour-coded pressure maps to assist clinical decision-making, based on ranking these from best to worst pressure distribution. The current study investigated whether such ranking is an appropriate method of assessment when compared to use of the numerical output of average and maximum pressure values (mmHg), yielded by the system.

METHOD

This community-based correlational study involved 27 multiple sclerosis clients (15 wheelchair users; 12 non-wheelchair users). Pressure maps were recorded on each participant's current seating surface and on six pressure reducing cushions, using the Force Sensing Array pressure mapping system. Outcome measures included (1) rank order of pressure maps based on visual interpretation by two occupational therapists, (2) average pressure (mmHg) and (3) maximum pressure (mmHg). Visual ranking of the colour-coded pressure maps was correlated with average and maximum pressure values for each map.

RESULTS

Correlations between visual ranking of maps and maximum pressures were high for six out of seven surfaces (p < 0.05) for non-wheelchair users; however, they were much less between average pressures and visual interpretation for the same cohort. Similarly, correlations between visual ranking of maps and average pressures for wheelchair users was minimal and was only noted as being high (p < 0.05) on two surfaces when considering maximum pressures and visual interpretation.

CONCLUSIONS

This study contests the usefulness of the visual ranking of pressure maps in interpreting interface pressures with MS clients, especially with wheelchair users. Visual interpretation of pressure maps by clinicians may be useful in eliminating inappropriate support surfaces from a selection, or those that display easily identifiable 'extremes' of pressure values. Clinicians need to incorporate and interpret the numerical data as well as pressure maps when conducting their assessment and making provision.

Cellular and subcellular compartmentation of Ni in the Eurasian serpentine plants Alyssum bracteatum, Alyssum murale (Brassicaceae) and Cleome heratensis (Capparaceae)

This study investigated the cellular and subcellular compartmentation of Ni in the Eurasian serpentine species Alyssum murale, Alyssum bracteatum and Cleome heratensis and a non-serpentine population of A. murale (as a control) grown in hydroponic culture. Plant growth responses and Ni uptake clearly revealed the higher Ni tolerance of serpentine plants than the non-serpentine plants. Serpentine A. murale and A. bracteatum grew better at elevated (0.01 mM) Ni in the nutrient solution, supporting the view that the Ni hyperaccumulators have a higher requirement for Ni than normal plants. Low shoot Ni content of C. heratensis in response to the high Ni treatments indicated that this species employs an avoidance strategy for Ni tolerance. Energy-dispersive X-ray microanalysis showed that Ni was highly concentrated in the cell walls and cell lumen, most likely the vacuoles, of leaf epidermis of A. murale and A. bracteatum rather than in the mesophyll cells. EDX spectra from leaves of the non-serpentine A. murale suggested that Ni accumulated in both epidermal and mesophyll cells but not in the epidermal cell walls. Growth reduction and Ni toxicity in plants of the non-serpentine A. murale could be due to accumulation of Ni in the lumen of leaf mesophyll cells. Our data suggest that cellular and subcellular compartmentation are both possible mechanisms for Ni tolerance employed by the serpentine A. murale and A. bracteatum.

Hammocking: the effect of cushion covers on interface pressure measurements

PURPOSE

To investigate the effects of the cushion covers on interface pressure measurements using pressure mapping technology.

METHODS

Sixty-one healthy participants were recruited for a laboratory-based study using a single group design. Participants were pressure mapped on a visco-elastic foam cushion and a foam and fluid pack cushion with their covers on and with their covers removed. An air-filled cushion was tested with two different types of covers, an incontinence cover and a 'Comfair' cover. Average and maximum pressures recorded at 6 mins by the Force Sensing Array pressure mapping system were used for statistical analysis.

RESULTS

There were no significant differences in maximum pressures for the three cushions tested with their covers on or with their covers removed. The cushion with the foam base and fluid pack did not demonstrate any significant differences in average pressure with the cover on or with the cover removed. However, the visco-elastic foam cushion showed significantly lower average pressures with the cover on (p=0.019). The air-filled cushion showed lower average pressures with the incontinence cover on, when compared to the Comfair cover (p=0.029).

CONCLUSION

Contrary to the belief that the process of hammocking may create surface tension within the cushion covers, which in turn may adversely affect the cushions ability to reduce interface pressure, the cushions tested in the current study did not show significantly lower interface pressure measurements with the covers removed. Therefore the covers did not adversely affect the cushion's ability to reduce interface pressure. The findings of this study require verification with disabled clients.

An investigation of the impact of the Force Sensing Array pressure mapping system on the clinical judgement of occupational therapists

OBJECTIVES

To examine the impact of pressure mapping technology on the clinical decisions of occupational therapists and to examine the role of the Braden Scale in assisting with the selection of pressure-reducing cushions.

DESIGN

Case studies.

SETTING

Community.

SUBJECTS

Forty clients.

INTERVENTIONS

Clients were pressure mapped on their current seating surface and on four pre-selected cushions by the principal researcher. An occupational therapist completed the Braden Scale and a decision tree to assist in recommending a suitable pressure-reducing cushion.

MAIN OUTCOME MEASURES

Interface pressure maps, Braden Scale, and the cushion recommended, using a decision tree to guide clinical judgement.

RESULTS

Thirty per cent (12) of the 40 cushions recommended were changed when the pressure maps from the Force Sensing Array (FSA) system were viewed. In 70% (26) of cases, the maps supported the cushion recommended. In 25% (10) of the cases, the maps showed that the client's current seating surface was unsuitable. After viewing the pressure maps, a surface other than the client's current surface was recommended in 47% (19) of the cases. There was a lack of agreement between the risk level of the clients as identified by the Braden Scale score, and the risk level of the clients as identified by the occupational therapist using a decision tree and the FSA maps.

CONCLUSION

Pressure mapping technology has a positive impact on clinical decisions regarding the provision of pressure-reducing cushions. Future research should examine the predictive validity of this technology. The Braden Scale may underpredict the risk level of the clients.

Mutations in folP associated with elevated sulfonamide MICs for Neisseria meningitidis clinical isolates from five continents

Sulfonamide resistance in meningococci is associated with mutations in the chromosomal gene folP, which encodes dihydropteroate synthase. Several mutations associated with resistance have been previously described, including amino acid substitutions at codons 31 and 194, a glycine-serine insertion at codons 195 and 196, and, recently, an additional mutation at nucleotide 682 (C682A). In this study, sulfisoxazole MICs were determined for 424 geographically diverse clinical isolates of Neisseria meningitidis, including all major subtypes. A subset of 134 isolates with MICs ranging from 0.5 to >64 microg/ml were assayed for the C682A mutation by real-time PCR, and 25 isolates were selected for folP gene sequencing. All isolates for which the sulfisoxazole MIC was >/=8 possessed the C682A mutation by real-time PCR or folP sequencing, and 34 of 35 isolates with a MIC of </=2 lacked this mutation. Of 16 sequenced isolates for which the sulfisoxazole MIC was >/=4, 15 possessed previously described mutations, including 10 at codon 31, 1 at codon 194, and 4 with the 2-amino-acid insertion codons 195 and 196; all 16 possessed the C682A mutation. The C682A mutation predicted elevated sulfonamides MICs for a large number of geographically diverse clinical isolates of meningococci. Detection of this mutation by real-time PCR or other methods may allow more wide-scale detection of meningococcal isolates with for which the sulfonamide MICs are elevated without resorting to multiple assays or folP gene sequencing, providing a simple, high-throughput screening method for use in public health and epidemiologic settings.

Detection of resistance to gatifloxacin and moxifloxacin in Streptococcus pneumoniae with the VITEK 2 instrument

A group of 72 pneumococcal isolates resistant or intermediate to levofloxacin and 124 pneumococcal isolates susceptible to fluoroquinolones were tested by the VITEK 2 instrument using investigational test cards and by a broth microdilution reference method. The VITEK 2 instrument performed well, detecting 52 of 60 (86.7%) gatifloxacin-resistant isolates and 22 of 23 moxifloxacin-resistant isolates, and did not falsely classify any susceptible isolates as resistant.

Detection of inducible clindamycin resistance of staphylococci in conjunction with performance of automated broth susceptibility testing

This study has shown that inducible clindamycin resistance in staphylococci can be detected by disk testing on sheep blood agar inoculum purity plates used with the bioMerieux VITEK 2. Tests of 150 erythromycin-resistant isolates correlated with standard D-zone tests on Mueller-Hinton agar and with PCR for erm(A), erm(C), and msr(A).

Practical disk diffusion method for detection of inducible clindamycin resistance in Staphylococcus aureus and coagulase-negative staphylococci

Resistance to macrolides in staphylococci may be due to active efflux (encoded by msrA) or ribosomal target modification (macrolide-lincosamide-streptogramin B [MLSB] resistance; usually encoded by ermA or ermC). MLSB resistance is either constitutive or inducible following exposure to a macrolide. Induction tests utilize closely approximated erythromycin and clindamycin disks; the flattening of the clindamycin zone adjacent to the erythromycin disk indicates inducible MLSB resistance. The present study reassessed the reliability of placing erythromycin and clindamycin disks in adjacent positions (26 to 28 mm apart) in a standard disk dispenser, compared to distances of 15 or 20 mm. A group of 130 clinical isolates of Staphylococcus aureus and 100 isolates of erythromycin-resistant coagulase-negative staphylococci (CNS) were examined by disk approximation; all CNS isolates and a subset of S. aureus isolates were examined by PCR for ermA, ermC, and msrA. Of 114 erythromycin-resistant S. aureus isolates, 39 demonstrated constitutive resistance to clindamycin, while 33 showed inducible resistance by disk approximation at all three distances. Only one isolate failed to clearly demonstrate induction at 26 mm. Of 82 erythromycin-resistant CNS isolates that contained ermA or ermC, 57 demonstrated constitutive clindamycin resistance, and 25 demonstrated inducible resistance, at 20 and 26 mm. None of the 42 S. aureus isolates or 18 CNS isolates containing only msrA and none of the erythromycin-susceptible isolates yielded positive disk approximation tests. Simple placement of erythromycin and clindamycin disks at a distance achieved with a standard disk dispenser allowed detection of 97% of S. aureus strains and 100% of CNS strains with inducible MLSB resistance in this study.

Identification of a 41 kDa protein embedded in the biosilica of scales and bristles isolated from Mallomonas splendens (Synurophyceae, Ochrophyta)

Cells of the photosynthetic protist Mallomonas splendens (Synurophyceae, Ochrophyta) are encased within a highly patterned wall or scale case that consists of silicified scales and bristles. In an effort to understand the mechanisms that unicellular protists utilize to produce elaborate, mineralized structures of great complexity and hierarchical structure, we identified and characterized a 41 kDa protein from purified scales/bristles isolated from M. splendens (SP41 for Scale Protein of 41 kDa). A cDNA encoding this protein was isolated and sequence analysis indicated that it is a novel protein. Polyclonal antibodies were generated against bacterially expressed SP41 and used to localize the protein throughout scale and bristle morphogenesis. Immunoelectron microscopy confirmed the biochemical data that SP41 is a component of mature scales and bristles, the protein localizing to silicified components of the purified extracellular matrix. During scale and bristle biogenesis within the cell, SP41 is deposited into a specialized Silica Deposition Vesicle (SDV) concomitant with silica deposition, a highly regulated event during scale and bristle formation. These results argue for SP41 playing a role in morphogenesis and/or silicification within the SDV during scale and bristle biogenesis.

The application of atomic force microscopy to topographical studies and force measurements on the secreted adhesive of the green alga Enteromorpha

Atomic force microscopy (AFM) enables the topographical structure of cells and biological materials to be resolved under natural (physiological) conditions, without fixation and dehydration artefacts associated with imaging methods in vacuo. It also provides a means of measuring interaction forces and the mechanical properties of biomaterials. In the present study, AFM has been applied for the first time to the study of the mechanical properties of a natural adhesive produced by a green plant cell. Swimming spores of the green alga Enteromorpha linza (L.) J. Ag. (7-10 microm) secrete an adhesive glycoprotein which provides firm anchorage to the substratum. Imaging of the adhesive in its hydrated state revealed a swollen gel-like pad, approximately 1 microm thick, surrounding the spore body. Force measurements revealed that freshly released adhesive has an adhesion strength of 173 +/- 1.7 mN m(-1) (mean +/- SE; n=90) with a maximum value for a single adhesion force curve of 458 mN m(-1). The adhesive had a compressibility (equivalent to Young's modulus) of 0.54 x 10(6) +/- 0.05 x 10(6) N m-2 (mean +/- SE; n=30). Within minutes of release the adhesive underwent a progressive 'curing' process with a 65% reduction in mean adhesive strength within an hour of settlement, which was also reflected in a reduction in the average length of the adhesive polymer strands (polymer extension) and a 10-fold increase in Young's modulus. Measurements on the spore surface itself revealed considerably lower adhesion-strength values but higher polymer-extension values than the adhesive pad, which may reflect the deposition of different polymers on this surface as a new cell wall is formed. The study demonstrates the value of AFM to the imaging of plant cells in the absence of fixation and dehydration artefacts and to the characterisation of the mechanical properties of plant glycoproteins that have potential utility as adhesives.

Rapid automated antimicrobial susceptibility testing of Streptococcus pneumoniae by use of the bioMerieux VITEK 2

The VITEK 2 is a new automated instrument for rapid organism identification and susceptibility testing. It has the capability of performing rapid susceptibility testing of Streptococcus pneumoniae with specially configured cards that contain enriched growth medium and antimicrobial agents relevant for this organism. The present study compared the results of testing of a group of 53 challenge strains of pneumococci with known resistance properties and a collection of clinical isolates examined in two study phases with a total of 402 and 416 isolates, respectively, with a prototype of the VITEK 2. Testing was conducted in three geographically separate laboratories; the challenge collection was tested by all three laboratories, and the unique clinical isolates were tested separately by the individual laboratories. The VITEK 2 results of tests with 10 antimicrobial agents were compared to the results generated by the National Committee for Clinical Laboratory Standards reference broth microdilution MIC test method. Excellent interlaboratory agreement was observed with the challenge strains. The overall agreement within a single twofold dilution of MICs defined by the VITEK 2 and reference method with the clinical isolates was 96.3%, although there were a number of off-scale MICs that could not be compared. The best agreement with the clinical isolates was achieved with ofloxacin and chloramphenicol (100%), and the lowest level of agreement among those drugs with sufficient on-scale MICs occurred with trimethoprim-sulfamethoxazole (89.7%). Overall there were 1.3% very major, 6.6% minor, and no major interpretive category errors encountered with the clinical isolates, although >80% of the minor interpretive errors involved only a single log(2) dilution difference. The mean time for generation of susceptibility results with the clinical isolates was 8.1 h. The VITEK 2 provided rapid, reliable susceptibility category determinations with both the challenge and clinical isolates examined in this study.

Revision of failed total hip arthroplasty with a proximal femoral modular cemented stem

We have designed a modular cemented femoral component for revision of failed total hip arthroplasty in which deficiency of the proximal femur is such as to require a variable extrafemoral portion of the stem. We present the results of the first 74 operations in 72 patients; 56 of the patients had grade-3 or grade-4 femoral deficiency as defined by Gustilo and Pasternak and 24 had fractures of the proximal femur, of which 22 were periprosthetic. There was or had been infection in 19 hips. At a mean follow-up of 5 years 9 months (1 to 12 years) nine stems were radiologically loose of which three had been revised. There were no failures in 45 cases in which there was fixation of the distal stem of 10 cm or more. Dislocation occurred in nine patients and there were four cases of infection in the 19 which were, or had been, infected previously. There were no neurovascular complications and no intraoperative femoral fractures. The femoral bone stock improved radiologically in 45 hips of which 29 showed considerable reformation of the proximal femur; 27 remained unchanged and two showed increasing osteoporosis.

Evaluation of the Dade MicroScan MICroSTREP antimicrobial susceptibility testing panel with selected Streptococcus pneumoniae challenge strains and recent clinical isolates

The MicroScan MICroSTREP panel is a recently marketed frozen broth microdilution panel for susceptibility testing of various streptococci, including Streptococcus pneumoniae. The panel contains 10 antimicrobial agents in cation-adjusted Mueller-Hinton broth supplemented with 3% lysed horse blood, similar in concept to the National Committee for Clinical Laboratory Standards (NCCLS) reference broth microdilution method for testing streptococci. A group of 210 isolates of S. pneumoniae were selected to include isolates with previously documented resistance to agents incorporated in the MICroSTREP panel, as well as recent invasive clinical isolates. All isolates were tested simultaneously with the MICroSTREP panel and an NCCLS reference panel whose drug concentrations were prepared to coincide with those of the MICroSTREP panel. Of the 210 isolates, 5 failed to grow in the MICroSTREP panel; 3 of those also did not grow in the reference panel. Essential agreement of MICs determined by the two methods (test MIC +/- one dilution of the reference MIC) was 99.6% overall and ranged from 98.0% with chloramphenicol to 100% with penicillin, ceftriaxone, erythromycin, tetracycline, and vancomycin. There were no very major or major interpretive category errors resulting from the MICroSTREP panel tests. Minor interpretive category errors ranged from 12.2% with cefotaxime and 9.8% with ceftriaxone (due mainly to clustering of MICs for the selected strains near the breakpoints) to 0% with chloramphenicol and vancomycin. These results indicate that the MicroScan MICroSTREP frozen panels provide susceptibility results with pneumococci that are essentially equivalent to results derived by the NCCLS reference broth microdilution procedure.

Rimantadine prophylaxis in children: a follow-up study

In a randomized, double-blind placebo-controlled clinical trial, we evaluated the prophylactic effectiveness of rimantadine in children (ages 1 to 18 years) against infection with influenza A (H3N2) and associated illness and the prevention of transmission of infection to adult members of the child's family. One hundred ten volunteers from 29 families completed this study during a naturally occurring outbreak of influenza A (H3N2). Influenza infections, defined as a positive viral throat culture or a 4-fold increase in antibody titer, occurred in 31.0% of children in the placebo group and 7.4% in the rimantadine group (P = 0.026). Clinical illness with laboratory evidence of influenza infection occurred in 24.1% of children in the placebo group and none in the rimantadine group (P = 0.007). Rimantadine was well-tolerated by the children, with no significant difference in reported adverse effects between the placebo and rimantadine groups. A combined analysis by families of these data and those of our similarly designed 1984 study, revealed that families in whom the children were given rimantadine had a significantly lower rate of influenza A infection and influenza-like illness compared with the families in whom the children were given placebo (68.8% vs. 18.8%, P less than 0.001) and (56.3% vs. 12.5%, P less than 0.001), respectively. We conclude that rimantadine prophylaxis of children appears to be an effective method to prevent influenza A (either H1N1 or H3N2) infection and illness in children.

Effectiveness of rimantadine prophylaxis of children within families

With recent studies suggesting that children are the main introducers of influenza infections into families, we conducted a placebo-controlled, double-blind, randomized trial to study the prophylactic effectiveness of rimantadine hydrochloride in children on the transmission of influenza A infections within families. One hundred forty-five volunteers from 35 families completed this study during a naturally occurring outbreak of influenza A (H1N1) infection. Influenza infections, defined as a positive viral throat culture or a fourfold increase in antibody titer, occurred in 31.7% of children in the placebo group and 2.9% of children in the rimantadine group. Clinical illness with laboratory evidence of influenza infection occurred in 17.0% of children in the placebo group and 0% of children in the rimantadine group. Rimantadine was well tolerated by the children, with no significant difference in reported side effects between the placebo and rimantadine groups. Influenza A infection occurred in 19.0% of adults whose children were receiving a placebo and 8.8% of adults whose children were receiving rimantadine. On the basis of our study, rimantadine prophylaxis of children appears to be an effective method to prevent influenza A infection in children. Additional studies are needed to demonstrate the effects of rimantadine prophylaxis of children on the incidence of influenza A infection in their parents.

Collaborative evaluation of the Abbott Avantage system for identification of frequently isolated nonfermentative or oxidase-positive gram-negative bacilli

The capability of the Abbott Avantage system to identify 10 species of commonly isolated glucose nonfermentative or oxidase-positive gram-negative bacilli in a 5-h test period was evaluated in a collaborative study. The Avantage nonenteric data base uses 20 biochemical test reactions performed in an expanded Abbott bacterial identification cartridge plus the results of a manual oxidase test. The species included in the Avantage data base are Acinetobacter anitratus, Acinetobacter Iwoffi, Aeromonas hydrophila, Flavobacterium meningosepticum-IIb group, Pseudomonas aeruginosa, Pseudomonas cepacia, Pseudomonas fluorescens-putida group, Pseudomonas maltophilia, Pasteurella multocida, and Plesiomonas shigelloides. The collaborative study included the testing of 200 coded challenge strains in all three laboratories and the subsequent testing of an additional group of 100 to 200 clinical isolates recovered independently by each laboratory. Reference identifications for all isolates were determined by conventional biochemical test reactions. The overall accuracy of identification of the coded challenge strains for the three laboratories was 97%, whereas 95% of 437 clinical isolates and selected stock cultures of clinical derivation were identified correctly.

Comparison of two automated instrument systems for rapid susceptibility testing of gram-negative bacilli

The Vitek AutoMicrobic System with GSC-plus cards and the Abbott MS-2 system were tested in parallel and the results were compared directly with those of a reference microdilution minimal inhibitory concentration (MIC) procedure on a group of 262 clinical isolates of the family Enterobacteriaceae and of Pseudomonas aeruginosa. Results of both systems were compared with the reference MIC for category agreement, and in addition, the Vitek MICs were compared with those obtained by the reference procedure. The Vitek system provided an essential category correlation of 89.4% for enteric bacteria and 97.0% for P. aeruginosa. Vitek MICs agreed within 1 twofold dilutional increment for 86.3% of the enteric bacteria tested and for 96.2% of the P. aeruginosa isolates. The Abbott MS-2 essential categoric agreement was 92.0% for enteric bacteria and 92.4% for P. aeruginosa. If only aminoglycosides or carbenicillin were considered for P. aeruginosa isolates, the essential category agreement was 92.5% for the Vitek and 93.3% for the MS-2. The majority of MS-2 category errors (13 of 19) with P. aeruginosa involved gentamicin results on isolates whose reference MICs were 8 micrograms/ml and whose MS-2 results were susceptible (MIC less than or equal to 4 micrograms/ml). Retesting of the P. aeruginosa isolates in calcium-supplemented MS-2 broth increased the essential agreement for the aminoglycosides to 97.5%.

Rapid identification of group D streptococci with the API 20S system

The API 20S system (Analytab Products) was evaluated as a means of identifying 209 isolates of Lancefield group D streptococci to the species level. Results were compared with those from a conventional tube biochemical identification system and from serological grouping. Use of the latest 20S computerized data base allowed species identification of 97% (203 of 209) of test isolates after a 4-h incubation period and 99% (208 of 209) of test isolates if supplemental overnight biochemical tests were used to clarify the identity of five Streptococcus bovis-variant isolates. The API 20S system appears to be a convenient and accurate method for rapid, same-day species identification of group D streptococci.

Ceftazidime levels in human breast milk

Ceftazidime in the breast milk of 11 puerperal women were determined by bioassay. Each patient received 2 g of ceftazidime intravenously every 8 h for 5 days. The mean (+/- standard deviation) ceftazidime concentrations in the milk were: 3.8 +/- 2.0 (before the next dose), 5.2 +/- 3.0 (1 h after), and 4.5 +/- 1.7 micrograms/ml (3 h after). Ceftazidime was excreted in breast milk at relatively constant levels between days 2 and 4 of therapy.

Pyridinium-2-azo-p-dimethylaniline chromophore, a new chromogenic cephalosporin for rapid beta-lactamase testing

A new chromogenic cephalosporin, pyridinium-2-azo-p-dimethylaniline chromophore, was evaluated for use in a rapid paper strip or tube test for the detection of beta-lactamases from a variety of microorganisms. A 1-min pyridinium-2-azo-p-dimethylaniline chromophore paper strip test was found to be a convenient and accurate method for the detection of beta-lactamase-producing strains of Haemophilus influenzae and Neisseria gonorrhoeae, although it could not be relied upon to detect beta-lactamases produced by staphylococci, enteric organisms, or Bacteroides fragilis.

Recovery and activation of hydroxymethylglutaryl coenzyme A reductase from rat small intestine

We describe a method for estimating the total activity of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase (EC 1.1.1.34) in the small intestine of rats. An homogenate of the whole small intestine is prepared rapidly and assayed directly to maximize the yield of enzyme and to minimize opportunity for uncontrolled change in activity. Fresh homogenate inhibits the expression of reductase in hepatic microsomes, has high HMG-CoA cleavage activity, and forms NADPH-independent metabolites which contaminate mevalonolactone isolated by thin-layer chromatography. When homogenate is preincubated, these interfering factors are decreased and reductase activity is increased. Part of this increase can be inhibited by F-. After freezing and preincubation, total reductase activity recovered from homogenates of small intestine from 300-g male rats at the middle of their dark period is 40 nmol mevalonate per min compared to 70 from hepatic microsomes. If F- is added at the time of homogenization, an activity of 11 nmol per min is recovered from each organ. Reductase in intestinal homogenate has an apparent Km for S-HMG-CoA of 4 microM.

Total hydroxymethylglutaryl CoA reductase activity in the small intestine and liver of insulin-deficient rats

We examined the effect of streptozotocin-induced diabetes on the rate-limiting enzyme in cholesterol synthesis, 3-hydroxy-3-methylglutaryl CoA reductase (EC 1.1.1.34), in liver and small intestine of rats. During the acute phase of insulin deficiency (first day), food intake, plasma cholesterol, and reductase specific activity in liver all decreased. By 3 days, food intake, plasma cholesterol, and reductase activity in small intestine were all increasing. After 1 week, total reductase activity in small intestine was 2.5 times normal, whereas activity in liver remained low. Thus diabetes shifted the major site of cholesterol synthesis from the liver to the small intestine. These data support the proposal that hyperphagia by diabetic rats leads to increased input of both dietary and newly synthesized cholesterol by the small intestine into thoracic lymph and thereby contributes significantly to their hypercholesterolemia. The possibility that diabetes affected the F--inhibitable activation of reductase in vitro was also tested. There was no evidence of an effect in small intestine, but activation of reductase in vitro was decreased by 1/3 in liver. These data suggest that, in liver, either the activity of the activator was decreased or the fraction of reductase in the active state was increased after more than 12 hr of insulin deficiency.

In vitro activities of moxalactam and cefotaxime against aerobic gram-negative bacilli

The in vitro activities of two new beta-lactam antibiotics, moxalactam disodium (LY 127935) and cefotaxime (HR-756), were compared with cefoxitin, cefamandole, cefuroxime, cephalothin, and, in some instances, carbenicillin, gentamicin, and amikacin against aerobic gram-negative bacilli. Test isolates included normally cephalosporin-resistant members of the Enterobacteriaceae and Pseudomonas spp. and a variety of nonfermentative or oxidase-positive bacteria. Both moxalactam and cefotaxime demonstrated impressive in vitro activities against both groups of microorganisms. The two new drugs were clearly more active than any of the other beta-lactam antibiotics against species of Escherichia, Citrobacter, Enterobacter, Klebsiella, Proteus, Providencia, Pseudomonas, and Serratia. An additive or synergistic effect could also be demonstrated with the majority of Pseudomonas and Serratia isolates when either moxalactam or defotaxime was combined with amikacin.

Comparison of moxalactam (LY127935) and cefotaxime against anaerobic bacteria

The in vitro activities of moxalactam (LY127935 [6059S]) and cefotaxime were compared with those of cefoxitin, cefamandole, cefuroxime, carbenicillin, and penicillin by agar dilution susceptibility testing of a variety of anaerobic bacteria. Moxalactam proved to be the most active agent tested against Bacteroides fragilis and other species of the B. fragilis group. Moxalactam and cefotaxime showed activity similar to the other drugs against the remaining species of Bacteroides, Fusobacterium, Actinomyces, Propionibacterium, and Veillonella. Penicillin was the most effective drug tested against most species of Clostridium, the anaerobic gram-positive cocci, and Eubacterium lentum.

In vitro activities of cefotaxime and moxalactam (LY127935) against Haemophilus influenzae

The in vitro activities of two new beta-lactam antibiotics, cefotaxime and moxalactam (LY127935), were compared with those of cefamandole, cefoxitin, cefuroxime, and ampicillin against both beta-lactamase-producing and non-beta-lactamase-producing isolates of Haemophilus influenzae. Both cefotaxime and LY127935 were highly active against all isolates irrespective of beta-lactamase production.

Sillitoe, Storey, Hines: their contribution to the sociology of sport and physical education

The place of sporting activity in literature is reviewed and attention is drawn to the outstanding depth and quality of much of the American writing in this genre. The focus of attention, however, in this paper, is the contribution of contemporary English literature. In recent years a number of novels, short stories and plays have translated sport into dramatic terms as well as placing such action within a recognisable and definable sociological framework. Selected writings by English authors Sillitoe, Storey and Hines are studied and examined to illustrate the many sources available to identify, describe, analyse and complement academic and empirical researches in the sociology of sport and physical education. There is unlimited scope for sports literature (especially in the North American situation) to provide a viable tool for sociological investigation.

Necrotizing fasciitis associated with Haemophilus aphrophilus. Report of a case

Necrotizing fasciitis, a serious infection requiring prompt antibiotic and surgical therapy, previously has not been associated with Haemophilus aphrophilus. We report a case of necrotizing fasciitis associated with methylphenidate abuse from which H aphrophilus was isolated. Surgical and antibiotic therapy based on in vitro susceptibility testing resulted in eradication of the infection.

Particle-based axenic media for tetrahymenids

Autoclavable, natural particulate media simplify axenic cultivation of tetrahymenid ciliates and presumably favor selection for phagotrophy. Viability is at least 2 months at room temperature (24-26 C) for the lipid-sensitive tetrahymenids Tetrahymena setosa, T. corlissi, T. paravorax, T. limacis, and T. patula, also for T. rostrata and (at 12 C), for strains of the T. pyriformis complex and Glaucoma chattoni. A typical medium consists of crude soy "lecithin" + skim milk powder + Saccharomyces cerevisiae cells. Other useful particules readily available commercially are: whole liver powder, cells of Micrococcus lysodeikticus and Escherichia coli, and powdered residue of liver which had been extracted with 70% ethanol ("liver No. 2). Preliminary experiments indicate that some of these media are suitable for the maintenance of Paramecium octaurelia stock 299S and Colpidium campylum. Such mixtures may serve as points of departure for devising media for more fastidious phagotrophs.