Potential of NIR spectroscopy for predicting cellulose nanofibril quality in commercial bleached Kraft pulp of Eucalyptus

Multivariate models were developed to classify cellulose nanofibril (CNF) fibrillation by a quality index from near infrared (NIR) spectra. Commercial pulps of Eucalyptus spp. were used to produce cellulose nanofibrils by means of a fibrillator mill. After each of the five passes through the mill, samples were collected and analyzed for energy consumption and fiber classification. As a standard, pulps were oxidized with TEMPO reagent followed by a single pass through the mill to compare the resulting quality of CNFs produced by each method. NIR spectra of CNFs were associated with quality indices determined by conventional laboratory analyses that included morphology, turbidity, mechanical properties, X-ray diffraction and quality index measurements. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were applied to the spectral and experimental data. Fibrillator milling to obtain CNFs was efficient and resulted in gel formation following the third pass through the mill. NIR spectroscopy combined with PLS-DA was used successfully to create a model to classify quality of CNFs with 96 % certainty in 3 wt% solutions. These findings suggest that NIR spectroscopy holds promise for estimating CNF quality in suspension, particularly in real-time industrial applications where reliable estimates are crucial.

Sequencing and functional validation of the JGI Brachypodium distachyon T-DNA collection

Due to a large and growing collection of genomic and experimental resources, Brachypodium distachyon has emerged as a powerful experimental model for the grasses. To add to these resources we sequenced 21 165 T-DNA lines, 15 569 of which were produced in this study. This increased the number of unique insertion sites in the T-DNA collection by 21 078, bringing the overall total to 26 112. Thirty-seven per cent (9754) of these insertion sites are within genes (including untranslated regions and introns) and 28% (7217) are within 500 bp of a gene. Approximately 31% of the genes in the v.2.1 annotation have been tagged in this population. To demonstrate the utility of this collection, we phenotypically characterized six T-DNA lines with insertions in genes previously shown in other systems to be involved in cellulose biosynthesis, hemicellulose biosynthesis, secondary cell wall development, DNA damage repair, wax biosynthesis and chloroplast synthesis. In all cases, the phenotypes observed supported previous studies, demonstrating the utility of this collection for plant functional genomics. The Brachypodium T-DNA collection can be accessed at http://jgi.doe.gov/our-science/science-programs/plant-genomics/brachypodium/brachypodium-t-dna-collection/.

Renewable hybrid nanocatalyst from magnetite and cellulose for treatment of textile effluents

A hybrid catalyst was prepared using cellulose nanofibrils and magnetite to degrade organic compounds. Cellulose nanofibrils were isolated by mechanical defibrillation producing a suspension used as a matrix for magnetite particles. The solution of nanofibrils and magnetite was dried and milled resulting in a catalyst with a 1:1 ratio of cellulose and magnetite that was chemically and physically characterized using light, scanning electron and transmission electron microscopies, specific surface area analysis, vibrating sample magnetometry, thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, catalytic potential and degradation kinetics. Results showed good dispersion of the active phase, magnetite, in the mat of cellulosic nanofibrils. Leaching and re-use tests showed that catalytic activity was not lost over several cycles. The hybrid material produced was tested for degradation of methylene blue dye in Fenton-like reactions resulting in a potential catalyst for use in degradation of organic compounds.

Antimicrobial Poly(lactic acid)-Based Nanofibres Developed by Solution Blow Spinning

The present study reports on the development of hybrid poly(lactic acid) (PLA) fibres loaded with highly crystalline bacterial cellulose nanowhiskers (BCNW) by the novel solution blow spinning method. Furthermore, fibres with antimicrobial properties were generated by incorporating carvacrol and THC as antimicrobial agents and the biocide effect against Listeria monocytogenes was studied. Initially, PLA blow spun fibres containing BCNW were optimized in terms of morphology and thermal properties. The addition of BCNW was seen to significantly increase the viscosity and surface tension of solutions, restricting the capacity to form fibres for concentrations greater than 30 wt.-% BCNW. 15 wt.-% BCNW was selected as the optimum nanofiller loading as it led to the most uniform fibres morphology, with BCNW homogeneously distributed along the fibres' axis. Subsequently, carvacrol and THC were incorporated into the fibres to confer them with antimicrobial properties, although the hydrophobic PLA matrix did not provide an efficient release of the antimicrobials. Thus, hydrophilic substances were added in order to trigger the antimicrobials release through water sorption mechanisms. The addition of the BCNW filler was not seen to significantly increase the antimicrobial capacity of the fibres by itself and, hence, gelatin was added to help promoting further the hydrophylicity and biocide performance of the fibres. Nevertheless, for the more hydrophilic THC, the biocide capacity of the fibres with gelatin was accentuated further by the presence of the BCNW.

Solid lipid particles in lipid films to control the diffusive release of 2-heptanone

BACKGROUND

Controlled-release formulations of bioactive agents are of increasing interest for effective pest control. Volatile 2-heptanone is a bioactive agent that has shown potential as a pesticide. The aim of this study was to investigate the kinetics of release of 2-heptanone incorporated into lipid films or composite solid lipid particle (SLP) films.

RESULTS

Effective 2-heptanone diffusivity was estimated to be between 0.1 and 2.5 mm(2)  day(-1) during the first week and between 0.05 and 0.1 mm(2)  day(-1) during the next 5 weeks. The films that showed better retention of 2-heptanone were the paraffin lipid films. Inclusion of SLPs into paraffin films increased the release rate of 2-heptanone, mainly owing to a decrease in the film firmness as the composite SLP film became less crystalline and more brittle. In contrast, SLPs decreased the kinetics of 2-heptanone release in Acetem films owing to an increase in the film firmness.

CONCLUSIONS

The results indicated that the use of SLPs as a method for controlled release can improve the delivery of the natural pesticide 2-heptanone if the SLPs have good compatibility with the matrix, leading to an increase in firmness of the films without increasing their porosity. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

Use of microscopy to assess bran removal patterns in milled rice

During rice milling, the bran and germ are successively removed from the caryopsis (kernel). Because bran and germ contain large quantities of lipid, the amount of lipid remaining on the kernel surface may be used as a method for the assessment of milling quality. Bulk samples of rice pureline varieties and an experimental hybrid were milled for 0, 10, 20, 30, and 40 s. Scanning electron microscopy (SEM) revealed that brown rice kernels had large contours of linear protuberances and depressions running lengthwise along the kernel surface. The protuberances were abraded successively during milling, but varying amounts of material remained in the depressions. Light microscopy combined with the lipid-specific probes Nile Blue A or Sudan Black B demonstrated that the material in the depressions observed with SEM was lipid. Sections of whole, milled rice kernels, prepared using a modified sectioning technique and stained with Nile Blue A, showed that portions of the embryo remain after milling and that lipid is located on or near the surface of the kernel. Differences in quantity and distribution of residual lipid as milling duration increased were documented photographically to indicate the extent to which the bran and embryo components were removed during milling. This paper provides proof of concept that residual lipid is a robust measure of the degree of milling.

Nanoemulsions prepared by a low-energy emulsification method applied to edible films

Catastrophic phase inversion (CPI) was used as a low-energy emulsification method to prepare oil-in-water (O/W) nanoemulsions in a lipid (Acetem)/water/nonionic surfactant (Tween 60) system. CPIs in which water-in-oil emulsions (W/O) are transformed into oil-in-water emulsions (O/W) were induced by changes in the phase ratio. Dynamic phase inversion emulsification was achieved by slowly increasing the water volume fraction (fw) to obtain O/W emulsions from water in oil emulsions. Composition and processing variables were optimized to minimize droplet size and polydispersity index (PdI). It was found that addition of the continuous phase to the dispersed phase following the standard CPI procedure resulted in the formation of oil droplets with diameters of 100-200 nm. Droplet size distribution during CPI and emulsification time depended on stirring speed and surfactant concentration. Droplet sizes in the inverted emulsions were compared to those obtained by direct emulsification: The process time to reach droplet sizes of around 100 nm was reduced by 12 times by using CPI emulsification. The Acetem/water nanoemulsion was also used as a carrier to incorporate oregano and cinnamon essential oils into soy protein edible films. The resulting composite films containing oregano oil showed better moisture barrier and mechanical properties compared to soy protein films.

Composite edible films based on hydroxypropyl methylcellulose reinforced with microcrystalline cellulose nanoparticles

It has been stated that hydroxypropyl methyl cellulose (HPMC) based films have promising applications in the food industry because of their environmental appeal, low cost, flexibility and transparency. Nevertheless, their mechanical and moisture barrier properties should be improved. The aim of this work was to enhance these properties by reinforcing the films with microcrystalline cellulose (MCC) at the nano scale level. Three sizes of MCC nanoparticles were incorporated into HPMC edible films at different concentrations. Identical MCC nanoparticles were lipid coated (LC) prior to casting into HPMC/LC-MCC composite films. The films were examined for mechanical and moisture barrier properties verifying how the addition of cellulose nanoparticles affected the water affinities (water adsorption/desorption isotherms) and the diffusion coefficients. The expected reinforcing effect of the MCC was observed: HPMC/MCC and HPMC/LC-MCC films showed up to 53% and 48% increase, respectively, in tensile strength values in comparison with unfilled HPMC films. Furthermore, addition of unmodified MCC nanoparticles reduced the moisture permeability up to 40% and use of LC-MCC reduced this value up to 50%. Water vapor permeability was mainly influenced by the differences in water solubility of different composite films since, in spite of the increase in water diffusivity values with the incorporation of MCC to HPMC films, better moisture barrier properties were achieved for HPMC/MCC and HPMC/LC-MCC composite films than for HPMC films.

Measurement and visualisation of focal cartilage thickness change by MRI in a study of knee osteoarthritis using a novel image analysis tool

We describe the application of a novel analysis method that provides detailed maps of changes in cartilage thickness measured from MRI scans for individuals and cohorts of patients together with regional measures. A cohort of osteoarthritis patients was imaged using a 1.0 T MR scanner over a 36-month period. Hyaline cartilage was manually segmented from a three-dimensional (3D) spoiled gradient-echo sequence with fat suppression. Representative outlines of the bone surfaces of the distal femur and proximal tibia were automatically generated from T₂ weighted images using statistical models of the shape and appearance of the bones. Cartilage thickness was measured from a dense set of points representing the bony surface. The models of the bones provided a common frame of reference, relative to which change maps were generated and aggregated across the cohort and anatomically corresponding subregions of the joint to be identified. In the reproducibility arm involving six patients, the thickness of cartilage had coefficients of variation of 2.66% within the tibiofemoral joint and 2.94% within the medial femoral condyle region. In the 9 patients (6 female, 3 male) who completed the 36-month study, the most striking observation was that lack of change in global measures of cartilage thickness concealed substantial focal changes. Specifically, the cartilage thickness within the tibiofemoral joint decreased by 0.85% per annum (95% CI -2.13% to 0.45%) with the medial femoral condyle as the region with the most significant change, decreasing by 2.43% per annum (uncorrected 95% CI -4.31% to 0.51%).

Effect of fiber treatments on tensile and thermal properties of starch/ethylene vinyl alcohol copolymers/coir biocomposites

Coir fibers received three treatments, namely washing with water, alkali treatment (mercerization) and bleaching. Treated fibers were incorporated in starch/ethylene vinyl alcohol copolymers (EVOH) blends. Mechanical and thermal properties of starch/EVOH/coir biocomposites were evaluated. Fiber morphology and the fiber/matrix interface were further characterized by scanning electron microscopy (SEM). All treatments produced surface modifications and improved the thermal stability of the fibers and consequently of the composites. The best results were obtained for mercerized fibers where the tensile strength was increased by about 53% as compared to the composites with untreated fibers, and about 33.3% as compared to the composites without fibers. The mercerization improved fiber-matrix adhesion, allowing an efficient stress transfer from the matrix to the fibers. The increased adhesion between fiber and matrix was also observed by SEM. Treatment with water also improved values of Young's modulus which were increased by about 75% as compared to the blends without the fibers. Thus, starch/EVOH blends reinforced with the treated fibers exhibited superior properties than neat starch/EVOH.

Isolation and Characterization of a Cold-Active Xylanase Enzyme from Flavobacterium sp

Xylan is the major component of hemicellulose, and xylan should be fully utilized to improve the efficiencies of a biobased economy. There are a variety of industrial reaction conditions in which an active xylanase enzyme would be desired. As a result, xylanase enzymes with different activity profiles are of great interest. We isolated a xylanase gene (xyn10) from a Flavobacterium sp. whose sequence suggests that it is a glycosyl hydrolase family 10 member. The enzyme has a temperature optimum of 30 degrees C, is active at cold temperatures, and is thermolabile. The enzyme has an apparent Km of 1.8 mg/ml and kcat of 100 sec-1 for beechwood xylan, attacks highly branched native xylan substrates, and does not have activity against glucans.

An episomal expression vector for screening mutant gene libraries in Pichia pastoris

Screening mutant gene libraries for isolating improved enzyme variants is a powerful technique that benefits from effective and reliable biological expression systems. Pichia pastoris is a very useful organism to express proteins that are inactive in other hosts such as Escherichia coli and Saccharomyces cerevisiae. However, most P. pastoris expression plasmids are designed to integrate into the host chromosome and hence are not as amenable to high-throughput screening projects. We have designed a P. pastoris expression vector, pBGP1, incorporating an autonomous replication sequence that allows the plasmid to exist as an episomal element. This vector contains the alpha-factor signal sequence to direct secretion of the mutant enzymes. Expression of the genes is driven by the constitutive GAP promoter, thus eliminating the need for timed or cell density-specific inductions. The pBGP1 plasmid was used to screen a xylanase gene library to isolate higher activity mutants.

Long-term follow up of patients with toenail onychomycosis after treatment with terbinafine

The long-term outcome of 111 patients treated with oral terbinafine for toenail onychomycosis with a novel treatment protocol was assessed a median of 138 weeks after entry into the trial. All but three patients had either one or two 12 week courses of terbinafine 250 mg daily. Of the 77 evaluable patients, 72.7% were still classified as responders (i.e. negative mycological culture and at least 3 mm of new unaffected nail growth) on reassessment. The present study shows that a favourable long-term outcome can be achieved in patients who have been treated with at least one 12 week course of terbinafine.

Non-dermatophytes in onychomycosis of the toenails

A multicentre trial for the treatment of dermatophyte onychomycosis of the toenails with terbinafine was carried out in Australia and New Zealand. Between eight and 12 nail samples were obtained from each of the 118 patients in the 48-week trial, and each sample was investigated by direct microscopy and culture for dermatophyte and non-dermatophyte fungi. Patients were randomized to treatment with terbinafine at 250 mg/day or placebo for the first 12 weeks of the study, then non-responders were offered a 12-week course of terbinafine from week 28. All patients had a dermatophyte infection. In 42 patients (36%) microscopy and mycological culture identified dermatophytes alone. In the remaining 76 patients (64%), a non-dermatophyte mould or yeast was also isolated at some stage during the trial, but in only three patients did the same non-dermatophyte persist in two or more successive nail specimens. The presence of a fungal contaminant in addition to a dermatophyte had no apparent effect on the efficacy of treatment with terbinafine. We conclude that non-dermatophyte moulds and yeasts are generally found as contaminating organisms in dermatophyte onychomycosis, secondary to the dermatophytes, and that they do not influence the outcome of treatment.

Restructuring critical care services. Part III: Successful implementation preparation

Successful implementation in a redesigning organization does not happen without a sound design, good implementation planning and effective leadership. The focus of the implementation preparation must change prior to and after the "go live" implementation date. Implementation preparation requires intentional steps to build systems, communicate effectively and develop operational understanding among clinicians, physicians and management. Early effort should focus on planning for efficient day-to-day operations, development of measurement systems and contingency planning. Immediately prior to and after implementation the focus should be on communication, goal setting, issues prioritization and fact-based issues resolution. After the first couple of months of implementation, the focus should move toward mentoring teams/individuals, building outcome measurement systems, identifying sources of future improvement and transferring more authority as appropriate to teams. Commit to comprehensive implementation preparation. Time spent on implementation preparation will pay large dividends during the challenging times of transitioning your organization to a redesigned world.

Significance of non-dermatophyte moulds and yeasts in onychomycosis

In a multicentre, randomised, double-blind, 48-week clinical trial, 118 patients with toe-nail onychomycosis were given terbinafine (250 mg daily) or placebo for 12 weeks, followed by 12 weeks of observation. Non-responders were offered 12 further weeks of terbinafine (250 mg daily) from week 28. Each patient had 8-12 consecutive nail specimens collected from the same nail, allowing for an assessment of the fungal nail flora from 1,321 nail specimens. By week 48, the overall mycological cure rate for terbinafine patients was 94%. 64% of patients had an underlying dermatophyte infection with at least 1 non-dermatophyte mould or yeast isolated from at least 1 specimen. These contaminants often overgrow or mask the presence of a dermatophyte. In only 2.5% of all patients was the same non-dermatophyte isolated from 2 or more consecutive specimens, probably representing secondary colonisation which exploits nutrients released by the underlying dermatophyte. The presence of incidental non-dermatophyte contaminants or secondary colonisers did not affect treatment outcome, and in this study treatment of the primary dermatophyte pathogen with terbinafine cleared the nails from infection in all cases. 80% of patients remained mycologically negative after 2 years.

Measuring the potency of pulp mill effluents for induction of hepatic mixed-function oxygenase activity in fish

A bioassay protocol was optimized for measuring the potency of effluents or waterborne chemicals for inducing mixed-function oxygenase (MFO) activity of rainbow trout (Oncorhynchus mykiss). Measurements of ethoxyresorufin O-deethylase (EROD) can be made with an established endpoint assay using large volumes of reagents and tissue. However, a new kinetic microplate assay offers significant savings in time, reagents, and sample volumes. Data are distributed lognormally and must be log transformed before statistical analyses. EROD activity increases with exposure time to pulp mill effluent, and a 4-d exposure provides a near-maximal response. Optimum fish size conforms to standard practices in fish toxicology; loading rates should not exceed 1 g of fish per liter of test solution per day. Feed should be withheld from test fish 48 h before testing to reduce the variance of measured activity, and anaesthetizing fish with MS-222 does not affect their response to MFO inducers. Pulp mill effluents do not lose their potency during 2-3 wk of exposure at temperatures ranging from -20 to 13 degrees C, whether stored in plastic or glass. Steel containers were associated with slight losses in potency. Bioassays of MFO induction in fish exposed to liquid effluents are practical and conform to standard practice for testing the lethality of waterbone chemicals. The results are sufficiently precise that differences among means based on live fish per treatment can be discriminated statistically when activity changes by threefold or more.

Death of a classified worker probably caused by overexposure to gamma radiation

This paper describes the case of an industrial radiographer who was seriously overexposed to gamma radiation. The exact circumstances of this exposure were not established but it was concluded that he was repeatedly irradiated probably to a total average whole body dose of at least 10 Gy over several years. Also, a much larger dose to a hand required its partial amputation. He developed myelodysplasia, which progressed to acute myeloid leukaemia from which he died. Karyotypic examination of the leukaemic blasts showed changes very similar to those associated with secondary leukaemia that may develop after radio or chemotherapy. The paper describes his medical case history, the investigation of his workplace, and the attempts to estimate his radiation dose by chromosomal analysis of blood lymphocytes and electron spin resonance of dental enamel and bone.

Rigorous management of insulin-dependent diabetes mellitus during pregnancy

The effect of rigorous management of insulin-dependent diabetes mellitus (IDDM) during pregnancy on the perinatal outcome was assessed by comparing 78 prepartum gravid patients with IDDM managed prospectively with 78 matched controls. The diabetic women were treated with insulin by either infusion pump or split-dose therapy, with the goal of normalization of the fasting blood sugars and hemoglobin Hb A1c values. Differences in the perinatal outcome were evaluated by either chi-square or analysis of variance. Of the women with IDDM, 14% where White class B, 43% class C, 26% class D, 17% classes R and F. The mean Hb A1c value in the first half of pregnancy was 8.49% +/- 2.30%, and 7.34% +/- 1.79% in the second half. Women with IDDM had higher rates of premature delivery (31% vs. 10%, P = 0.003), pre-eclampsia (15% vs. 5%, P = 0.035), and cesarean section (55% vs. 27%, P = 0.002). Complications of infants born to diabetic mothers included large size for gestational age (41% vs. 16%, P = 0.0002), hypoglycemia (14% vs. 1%, P = 0.0025), hyperbilirubinemia (46% vs. 23%, P = 0.0002), and respiratory distress (12% vs. 1%, P = 0.008). The Apgar scores and mortality were similar. Congenital malformations occurred in 7.7% of infants of diabetic mothers and 1.3% of controls (P = 0.05). The maternal Hb A1c level did not correlate with the infant size for gestation. Although the improved medical management of IDDM has decreased neonatal mortality, significant perinatal complications persist.

Dissolved inorganic nitrogen budget for a forested catchment at Beddgelert, North Wales

An input-output budget for dissolved inorganic-N in a small forested catchment in North Wales is presented. From 1982 to 1990, bulk precipitation inputs averaged 10.3 kg ha(-1) year(-1), whereas throughfall inputs in 1983-1984 were 20.3 kg ha(-1) year(-1). Streamwater outputs were consistently larger than bulk precipitation inputs, averaging 14.6 kg ha(-1) year(-1). Inorganic-N in the forest stream was predominantly nitrate and concentrations were substantially higher than in a nearby moorland stream. Both streams showed seasonal trends in nitrate concentration, with highest concentrations occurring in summer in the forest stream but in winter in the moorland stream. Nitrate concentration in the forest stream increased with increasing soil temperature up to approximately 7 degrees C and decreased at higher temperatures. Nitrification is thought to be responsible for nitrate production at temperatures both below and above 7 degrees C, but root uptake becomes significant only at the higher temperatures. In the forest, dry deposition and cloudwater inputs of inorganic-N are responsible for increased nitrogen fluxes in throughfall compared with wet deposition. Mineralization and nitrification in excess of plant needs causes the organic soil horizons to act as a net source of dissolved inorganic-N. Nitrogen transformations in the soil lead to soil acidification at a rate of 1.0 keq ha(-1) year(-1).

Duodenal perforation after laparoscopic cholecystectomy

A case is reported of duodenal perforation complicating laparoscopic cholecystectomy performed by laser dissection. The importance of investigating a patient with persistent shoulder-tip pain following this technique to exclude a subphrenic abscess is emphasised.

Identification and localization of carbonic anhydrase in two chlorella species

Carbonic anhydrase (CA) activity and localization have been examined in two species of the eukaryotic green alga Chlorella. Mass spectrometric and potentiometric assays of CA activity indicate that C. ellipsoidea contains very little extracellular CA activity whereas C. saccharophila exhibits significant extracellular activity when grown at alkaline pH values. Extracellular CA activity appears to be correlated with the presence of a 36 kilodalton polypeptide that was detected immunologically using a polyclonal antibody directed against the 37 kilodalton Chlamydomonas CA monomer. Both Chlorella species and enzymatically isolated C. ellipsoidea chloroplasts also contain an immunologically similar 38 kilodalton polypeptide that may be a cytosolic or chloroplastic form of CA.

Meconium aspiration syndrome: intrapartum and neonatal attributes

To identify the fetus and newborn at risk for meconium aspiration syndrome the perinatal characteristics of 238 infants delivered through meconium-stained amniotic fluid were prospectively examined. All infants with meconium-stained amniotic fluid were routinely suctioned with a DeLee apparatus before tracheal intubation and suctioning. The type and presence of meconium in the trachea, neonatal breathing before intubation, and Apgar scores were recorded in the delivery room. Intrapartum fetal monitoring data were collected for 80% (190/238) of the mothers and umbilical artery pH for 74% (177/238) of the newborns. Despite suctioning with a DeLee apparatus and endotracheal suctioning, meconium was present in the trachea in 87/238 (37%) and meconium aspiration syndrome developed in 22 (9.2%). A total of 73% of newborns who had meconium aspiration syndrome were delivered through thick meconium. Thick meconium, the presence of fetal tachycardia, and absence of intrapartum fetal cardiac accelerations identified the fetus at high risk for meconium aspiration syndrome. The presence of these monitoring findings and thick meconium should alert obstetricians to the possibility of a fetus that requires intervention. Low umbilical artery pH, Apgar scores less than 5, and meconium in the trachea further characterized the newborn at high risk for meconium aspiration syndrome. The combination of these findings may best identify the infant delivered through meconium-stained amniotic fluid who requires close observation for meconium aspiration syndrome.

Respiratory distress during total parenteral nutrition

We report on a patient who developed fatal respiratory distress two days after starting parenteral feeding for malnutrition complicating Crohn's disease. Post mortem examination revealed pulmonary collapse secondary to mediastinal leak of the infusion fluid due to an undiagnosed erosion of the vascular catheter tip through the brachiocephalic vein.

Comparison of cardiac effects of enflurane, isoflurane, and halothane in the dog heart-lung preparation

Minimum alveolar concentration (MAC) was determined in intact dogs (N = 10 for each anesthetic) to be 2.12 +/- 0.04 vol% for enflurane (ENF), 1.28 +/- 0.04 vol% for isoflurane (ISO), and 0.94 +/- 0.03 vol% for halothane (HAL). Then, the direct cardiac effects of these three anesthetics were studied at 0.36, 0.6, 1.0, and 1.2 MAC in the dog heart-lung preparation (HLP): an in situ whole heart preparation devoid of major extracardiac influences and reflex control. All three agents produced concentration-dependent decreases in heart rate (HR) that became significantly different from control at 0.6 MAC. HAL and ISO reduced +dP/dtmax by the same degree at all MAC levels, becoming statistically significant at 0.6 MAC, while a significant reduction in +dP/dtmax for ENF occurred first at 1.0 MAC. Marked increases in left atrial pressure (LAP) were observed at 1.0 MAC for all anesthetics and the first significant depression of systemic output (SO) occurred at 1.0 MAC. Each agent produced significant shifts of the left ventricular function curves (LVFC) to the right with each consecutive MAC fraction. Marked reductions in the slope of the LVFC were first observed at 1.0 MAC, and this change in slope was more pronounced with ENF. At 1.2 MAC, ENF seemed to produce a more severe cardiodepression than HAL or ISO, as suggested by a greater incidence of cardiac failure; however, this was not statistically significant. In general, the data suggest that at MAC fractions up to 0.6, ENF is less cardiodepressant than ISO or HAL, but that ENF has a tendency to be more depressant than HAL or ISO at concentrations higher than 1.0 MAC.

The relationship between cadmium, zinc, and birth weight in pregnant women who smoke

It is universally accepted that smoking during pregnancy results in decreased infant birth weight. However, the mechanism for decreased birth weight is not completely understood. This study tested the hypothesis that the cadmium/zinc interaction in the maternal-fetal-placental unit of the mother who smokes could be related to birth weight. Thiocyanate was used as the index of smoking status and atomic absorption spectroscopy was used to determine trace elements. Results show that cord vein red blood cell zinc and maternal whole blood cadmium levels are significant predictors of infant birth weight when variance that is due to clinical factors and thiocyanate is controlled with stepwise multiple regression techniques (n = 202). Bivariate correlation techniques showed that the factors affecting birth weight were different in the smoking and nonsmoking groups. For example, in nonsmokers (n = 125), the cord vein red blood cell zinc level was positively related to birth weight. In smokers (n = 77), maternal whole blood cadmium, placental cadmium, and placental zinc levels were negatively related to birth weight; the ratio of placental zinc to placental cadmium and the cord vein red blood cell zinc level were positively related to birth weight. The results suggest that increased maternal cadmium and decreased cord vein red blood cell zinc levels in infants of smokers may be significant clinically since increased maternal whole blood cadmium and decreased cord vein red blood cell zinc levels are both significantly related to decreased birth weight.

Neonatal complications following in utero exposure to intravenous ritodrine

Intravenous administration of ritodrine for tocolysis has been associated with maternal cardiovascular and metabolic changes. Studies with other tocolytic agents, such as isoxsuprine, have shown an increased neonatal morbidity among infants born soon after failure of such therapy. We examined the potential side effects of maternal intravenous ritodrine therapy in 58 neonates born within 12 h following discontinuation of maternal medication. 'Low dextrostix' was significantly greater in the ritodrine exposed neonates (p less than 0.05) than in the controls. It occurred within a mean 1.0 +/- 0.5 h following birth. The mean 1 min and 5 min Apgar scores, neonatal pH, bicarbonate levels, hypotension and neonatal mortality were comparable in the ritodrine-exposed and control groups of neonates. The occurrence of any of the neonatal morbidity variables, including 'low dextrostix' was not related either to the total dose of ritodrine used or to the interval between drug discontinuation and delivery. Administration of ritodrine by the standard protocol to stop preterm labor is not associated with any significant increase in neonatal morbidity.

The Role of External Carbonic Anhydrase in Inorganic Carbon Acquisition by Chlamydomonas reinhardii at Alkaline pH

The role of external carbonic anhydrase in inorganic carbon acquisition and photosynthesis by Chlamydomonas reinhardii at alkaline pH (8.0) was studied. Acetazolamide (50 micromolar) completely inhibited external carbonic anhydrase (CA) activity as determined from isotopic disequilibrium experiments. Under these conditions, photosynthetic rates at low dissolved inorganic carbon (DIC) were far greater than could be maintained by CO(2) supplied from the spontaneous dehydration of HCO(3) (-) thereby showing that C. reinhardii has the ability to utilize exogenous HCO(3) (-). Acetazolamide increased the concentration of DIC required to half-saturate photosynthesis from 38 to 80 micromolar, while it did not affect the maximum photosynthetic rate. External CA activity was also removed from the cell-wall-less mutant (CW-15) by washing. This had no effect on the photosynthetic kinetics of the algae while the addition of acetazolamide to washed cells (CW-15) increased the K((1/2)) (DIC) from 38 to 80 micromolar. Acetazolamide also caused a buildup of the inorganic carbon pool upon NaHCO(3) addition, indicating that this compound partially inhibited internal CA activity. The effects of acetazolamide on the photosynthetic kinetics of C. reinhardii are likely due to the inhibition of internal rather than a consequence of the inhibition of external CA. Further analysis of the isotopic disequilibrium experiments at saturating concentration of DIC provided evidence consistent with active CO(2) transport by C. reinhardii. The observation that C. reinhardii has the ability to take up both CO(2) and bicarbonate throws into question the role of external CA in the accumulation of DIC in this alga.

Photosynthetic Adaptation by Synechococcus leopoliensis in Response to Exogenous Dissolved Inorganic Carbon

Synechococcus leopoliensis was grown over a wide range of dissolved inorganic carbon (DIC) concentrations (4-25,000 micromolar) which were obtained by varying culture pH (6.2-9.6) and the CO(2) concentration of the gas stream (36-50,000 microliters per liter). The [DIC] required to half-saturate photosynthesis (K((1/2)) (DIC)) was found to vary depending upon the ambient DIC concentration at which the cells were grown. Low [DIC] grown cells exhibited low values of K((1/2)) (DIC) (4.7 micromolar) whereas cells grown at high [DIC] exhibited high values of K((1/2)) (DIC) (1-2.5 millimolar). Intermediate concentrations of DIC produced intermediate values. Changes in K((1/2)) (DIC) appeared to be solely a function of [DIC] and were independent of both culture pH and CO(2) concentration. As changes in K((1/2)) (DIC) occur in response to DIC concentrations commonly found in natural systems we suggest this adaptation may be of ecological significance.

Maternal obesity as a risk factor in gestational diabetes

Maternal obesity has been associated with both gestational diabetes mellitus (GDM) and neonatal macrosomia. Most studies of obesity in pregnancy have demonstrated an increased risk for GDM. However, the contribution of obesity as an added risk in GDM has not been examined. The purpose of this study was to examine the contribution of obesity as a risk factor to perinatal morbidity in gestationally diabetic women by comparing the maternal and neonatal outcome in obese and nonobese gestationally diabetic women. From 1979 to 1983, the maternal, intrapartum, and neonatal characteristics of all prepartum gravid patients with GDM were examined. Of the 158 patients with documented GDM, 62 (39%) were obese (weight greater than 90 kg). There was no difference in maternal age (obese 29.3 +/- 5.4 years, nonobese 28.7 +/- 6.5 years) parity, or prepartum risk score between the obese and nonobese patients. The incidence of prematurity, pre-eclampsia, fetal distress, and primary cesarean sections were not different between the groups. There were no differences in Apgar scores, gestational age, or perinatal morbidity. However, the obese patients delivered heavier neonates expressed as mean birthweight (obese 3667 +/- 682 gms, nonobese 3331 +/- 750 gms. P less than .01), the number of macrosomic (greater than 4 kg) neonates (obese 37%, nonobese 14%, P less than .001) and K-score, (obese 0.8 +/- 1, nonobese 0.4 +/- 9, P less than .05). These data indicate that obese patients with GDM have an increased risk of neonatal macrosomia.(ABSTRACT TRUNCATED AT 250 WORDS)

Gestational diabetes mellitus. Is further improvement necessary?

The maternal antepartum, intrapartum, and neonatal characteristics of 158 patients with gestational diabetes mellitus (GDM) attending a large teaching hospital between 1979 and 1983 were described and compared with a matched nondiabetic control group. The primary cesarean section rate in patients with GDM (18%) was significantly greater than in the control group (11%, P less than 0.04). Neonatal macrosomia, as reflected in mean birthweight (P less than 0.04), the number of neonates weighing greater than 4 kg (P less than 0.05) and large-for-gestational-age infants (P less than 0.05), and the birthweight adjusted for gestational age (K-score, P less than 0.01) was significantly increased in the diabetic group. The characteristics of patients with GDM treated with diet alone and diet and insulin together were examined. The insulin-therapy group was characterized by more patients older than 25 yr (P less than 0.01) and a higher mean birthweight (3743 +/- 677 g) (P less than 0.02) than the diet-alone group. This may reflect an increased magnitude of glucose intolerance in the insulin-treated group. Obese patients with GDM delivered heavier neonates than the nonobese patients with GDM (P less than 0.01). Although there was no difference between the groups, perinatal mortality was present in this study. These data indicate that the major perinatal morbidity in GDM included increased cesarean section for fetal macrosomia. Early diagnosis with strict diagnostic criteria and rigid antenatal surveillance may result in further improvements in outcome.

The diagnosis of aortic graft-enteric fistulae by computed tomography

A number of techniques have been used to diagnose aortic graft-enteric fistulae. These are reviewed and their value assessed. Three patients are described in whom the diagnosis was correctly made from characteristic appearances seen on a computed tomography (CT) scan. Further experience may show that CT scanning has an important role in the detection of this condition.