High resolution solid state NMR in paramagnetic metal-organic frameworks

We study the metal-organic framework (MOF) ZIF-67 with ¹H and ¹³C nuclear magnetic resonance (NMR). In addition to the usual orbital chemical shifts, we observe spinning sideband manifolds in the NMR spectrum due to hyperfine interactions of the paramagnetic cobalt with ¹H and ¹³C. Both orbital and paramagnetic chemical shifts are in good agreement with values calculated from first principles, allowing high-confidence assignment of the observed peaks to specific sites within the MOF. Our measured resonance shifts, line shapes, and spin lattice relaxation rates are also consistent with calculated values. We show that molecules in the pores of the MOF can exhibit high-resolution NMR spectra with fast spin lattice relaxation rates due to dipole-dipole couplings to the Co²⁺ nodes in the ZIF-67 lattice, showcasing NMR spectroscopy as a powerful tool for identification and characterization of "guests" that may be hosted by the MOF in electrochemical and catalytic applications.

Dual Task Performance Is Associated with Amyloidosis in Cognitively Healthy Adults

BACKGROUND

Preclinical Alzheimer's disease (AD) provides an opportunity for the study and implementation of interventions and strategies aimed at delaying, mitigating, and preventing AD. While this preclinical state is an ideal target, it is difficult to identify efficiently and cost-effectively. Recent findings have suggested that cognitive-motor dual task paradigms may provide additional inference.

OBJECTIVES

Investigate the relationship between dual task performance and amyloidosis, suggestive of preclinical Alzheimer's disease and whether dual task performance provides additional information beyond a cognitive composite, to help in the identification of amyloidosis.

DESIGN

Cross-sectional.

SETTING

Outpatient specialty brain health clinical research institution in the United States.

PARTICIPANTS

52 cognitively healthy adults.

MEASUREMENTS

The data included demographics, amyloid standardized uptake value ratio obtained via florbetapir-PET, neuropsychological testing, apolipoprotien E genotype, and dual task performance measures. Data were analyzed via hierarchal multiple linear regression or logistic regression, controlling for age, education, and apolipoprotien E genotype. Receiver operating characteristic curves were plotted, and sensitivity and specificity calculated via 2x2 contingency tables.

RESULTS

There was a moderate relationship (rs>.30) between motor and cognitive dual task effects and amyloid standardized uptake value ratio (ps<.042). A strong relationship (r=.58) was found between combined dual task effect, a measure of automaticity derived from dual task performance, and amyloid standardized uptake value ratio (p<.001). Additionally, combined dual task effect showed promise in its unique contributions to amyloid standardized uptake value ratio, accounting for 7.8% of amyloid standardized uptake value ratio variance beyond cognitive composite scores (p=.018). Additionally, when incorporated into the cognitive composite, combined dual task effect resulted in improved diagnostic accuracy for determining elevated amyloid standardized uptake value ratio, and increased the sensitivity and specificity of the cognitive composite.

CONCLUSSION

Dual task performance using the combined dual task effect, a measure of automaticity, was a moderate predictor of cerebral amyloidosis, which suggests that it has utility in the screening and diagnosis of individuals for preclinical AD. Additionally, when combined with the cognitive composite, the combined dual task effect improves diagnostic accuracy. Further research is warranted.

Development of a long-acting direct-acting antiviral system for hepatitis C virus treatment in swine

Chronic hepatitis C virus (HCV) infection is a leading cause of cirrhosis worldwide and kills more Americans than 59 other infections, including HIV and tuberculosis, combined. While direct-acting antiviral (DAA) treatments are effective, limited uptake of therapy, particularly in high-risk groups, remains a substantial barrier to eliminating HCV. We developed a long-acting DAA system (LA-DAAS) capable of prolonged dosing and explored its cost-effectiveness. We designed a retrievable coil-shaped LA-DAAS compatible with nasogastric tube administration and the capacity to encapsulate and release gram levels of drugs while resident in the stomach. We formulated DAAs in drug-polymer pills and studied the release kinetics for 1 mo in vitro and in vivo in a swine model. The LA-DAAS was equipped with ethanol and temperature sensors linked via Bluetooth to a phone application to provide patient engagement. We then performed a cost-effectiveness analysis comparing LA-DAAS to DAA alone in various patient groups, including people who inject drugs. Tunable release kinetics of DAAs was enabled for 1 mo with drug-polymer pills in vitro, and the LA-DAAS safely and successfully provided at least month-long release of sofosbuvir in vivo. Temperature and alcohol sensors could interface with external sources for at least 1 mo. The LA-DAAS was cost-effective compared to DAA therapy alone in all groups considered (base case incremental cost-effectiveness ratio $39,800). We believe that the LA-DAA system can provide a cost-effective and patient-centric method for HCV treatment, including in high-risk populations who are currently undertreated.

A gastric resident drug delivery system for prolonged gram-level dosing of tuberculosis treatment

Multigram drug depot systems for extended drug release could transform our capacity to effectively treat patients across a myriad of diseases. For example, tuberculosis (TB) requires multimonth courses of daily multigram doses for treatment. To address the challenge of prolonged dosing for regimens requiring multigram drug dosing, we developed a gastric resident system delivered through the nasogastric route that was capable of safely encapsulating and releasing grams of antibiotics over a period of weeks. Initial preclinical safety and drug release were demonstrated in a swine model with a panel of TB antibiotics. We anticipate multiple applications in the field of infectious diseases, as well as for other indications where multigram depots could impart meaningful benefits to patients, helping maximize adherence to their medication.

Astronomical time-of-flight photon speedometer

A dual-band, fiber-optic, photon time-of-flight instrument was developed. Its design was optimized for measuring the velocity of visible photons emanating from relatively dim astronomical sources (apparent magnitude m>12), such as distant galaxies and quasars. We report the first direct photon group velocity measurements for extragalactic objects. The photon group velocity is found to be 3.00±0.03×10⁸ ms^-1 and is invariant, within experimental error, over the range of redshifts measured (0≤z≤1.33). This measurement provides additional validation of general relativity and is consistent with the Friedmann-Lemaître-Robertson-Walker and hyperbolic anti-de Sitter metrics but not with the elliptical de Sitter metric.

Liver Histopathology and Liver and Serum Alanine Aminotransferase and Alkaline Phosphatase Activities in Epileptic Dogs Receiving Phenobarbital

Phenobarbital (PB) therapy is frequently associated with elevated serum alanine aminotransferase (ALT) and alkaline phosphatase (AP) activities in dogs without clinical signs of liver disease. The goal of this study was to determine if increased serum ALT and AP activities in clinically healthy PB-treated epileptic dogs are due to hepatic enzyme induction or to subclinical liver injury. Liver biopsies were obtained from 12 PB-treated dogs without clinical signs of liver disease but with elevated serum ALT and/or AP activities or both. Liver biopsies were obtained from eight healthy control dogs not receiving PB. Biopsies were evaluated histopathologically (all dogs) and liver homogenates were assayed for ALT (all dogs) and AP (six treated dogs, all controls) activities. As a positive control, liver cytochrome P4502B, an enzyme known to be induced by PB, was measured by benzyloxyresorufin- O-dealkylase activity and immunoblotting (five treated dogs, all controls). Serum AP isoenzyme analyses were performed. Results showed that ALT and AP activities in liver homogenates were not increased in treated dogs compared with controls, whereas the positive control for induction, CYP2B, was dramatically increased in treated dogs. Histopathological examination of liver biopsies revealed more severe and frequent abnormalities in treated dogs compared to controls, but similar types of abnormalities were found in both groups. Serum AP isoenzyme analyses in treated dogs demonstrated increased corticosteroid-induced and liver isoenzyme activities compared to controls. Results do not support induction of ALT or AP in the liver as the cause of elevated serum activities of these enzymes due to PB.

Intravitreal aflibercept for macular oedema secondary to central retinal vein occlusion in patients with prior treatment with bevacizumab or ranibizumab

PurposeTo report the visual and anatomic outcomes in eyes with macular oedema (MO) secondary to central retinal vein occlusion (CRVO) that were switched from either intravitreal bevacizumab or ranibizumab to intravitreal aflibercept.MethodsTwo-center retrospective chart review. Eyes with MO secondary to CRVO that received a minimum of three intravitreal injections of bevacizumab or ranibizumab and were switched to intravitreal aflibercept for persistent or recurrent MO not responding to either bevacizumab and/or ranibizumab.ResultsIn all 42 eyes of 42 patients were included in the study. The median visual acuity before the switch was 20/126, 1 month after the first injection of aflibercept 20/89 (P=0.0191), and at the end of the follow-up 20/100 (P=0.2724). The median CRT before the switch was 536 μm, 1 month after the first injection of aflibercept 293.5 μm (P=0.0038), and at the end of the follow-up 279 μm (P=0.0013 compared to before the switch). The median number of weeks between injections before the switch was 5.6 and after the switch was 7.6 (P<0.0001).ConclusionConverting eyes with refractory MO due to CRVO to aflibercept can result in stabilization of the vision, improved macular anatomy, and extension of the injection interval.

Spray desorption collection of free fatty acids onto a solid phase microextraction fiber for trap grease analysis in biofuel production

Spray desorption collection (SDC) is a sample collection and preparation method that allows for the collection of soluble chemical compounds directly from solid surfaces. Here the analysis of trap grease, a potential biofuel feedstock, is demonstrated by combining SDC with solid phase micro-extraction (SPME) collection followed by direct GC-MS analysis. The SPME fiber collects droplets of solvent, which has picked up analytes from the solid sample surface. It is found that the SDC-SPME combination is a simple and convenient method to collect sample components from surfaces when they are less volatile than heptanoic acid, while the collection efficiency of highly volatile compounds is increasingly reduced due to the purging effect of the nebulising gas. In a real trap grease analysis the SDC-SPME method was able to analyze both the longer chain fatty acids in the sample, important for energy production evaluation of the sample, as well as volatile sample components down to pentanoic acid, which may add to off-odours produced during biofuel use.

Contribution of anthropogenic and natural sources to atmospheric methane variability

Methane is an important greenhouse gas, and its atmospheric concentration has nearly tripled since pre-industrial times. The growth rate of atmospheric methane is determined by the balance between surface emissions and photochemical destruction by the hydroxyl radical, the major atmospheric oxidant. Remarkably, this growth rate has decreased markedly since the early 1990s, and the level of methane has remained relatively constant since 1999, leading to a downward revision of its projected influence on global temperatures. Large fluctuations in the growth rate of atmospheric methane are also observed from one year to the next, but their causes remain uncertain. Here we quantify the processes that controlled variations in methane emissions between 1984 and 2003 using an inversion model of atmospheric transport and chemistry. Our results indicate that wetland emissions dominated the inter-annual variability of methane sources, whereas fire emissions played a smaller role, except during the 1997-1998 El Niño event. These top-down estimates of changes in wetland and fire emissions are in good agreement with independent estimates based on remote sensing information and biogeochemical models. On longer timescales, our results show that the decrease in atmospheric methane growth during the 1990s was caused by a decline in anthropogenic emissions. Since 1999, however, they indicate that anthropogenic emissions of methane have risen again. The effect of this increase on the growth rate of atmospheric methane has been masked by a coincident decrease in wetland emissions, but atmospheric methane levels may increase in the near future if wetland emissions return to their mean 1990s levels.

Unexpected Changes to the Global Methane Budget over the Past 2000 Years

We report a 2000-year Antarctic ice-core record of stable carbon isotope measurements in atmospheric methane (delta13CH4). Large delta13CH4 variations indicate that the methane budget varied unexpectedly during the late preindustrial Holocene (circa 0 to 1700 A.D.). During the first thousand years (0 to 1000 A.D.), delta13CH4 was at least 2 per mil enriched compared to expected values, and during the following 700 years, an about 2 per mil depletion occurred. Our modeled methane source partitioning implies that biomass burning emissions were high from 0 to 1000 A.D. but reduced by almost approximately 40% over the next 700 years. We suggest that both human activities and natural climate change influenced preindustrial biomass burning emissions and that these emissions have been previously understated in late preindustrial Holocene methane budget research.

14N magnetic resonance for materials detection in the field

Nitrogen is prevalent in many materials, both naturally occurring and man-made. In particular, it is found in many explosives and other contraband materials. One technique for the detection of such materials in the field is the use of the magnetic resonance signal from the nearly 100% abundant, spin-1, 14N nuclei. Some of the difficulties with such measurements in the field include spurious signals from acoustic resonances, radio-frequency interference, and generally low signal-to-noise ratios. A summary of recent work by the authors to help mitigate these difficulties is presented.

Gate-controlled spin-orbit quantum interference effects in lateral transport

In situ control of spin-orbit coupling in coherent transport using a clean GaAs/AlGaAs two-dimensional electron gas is realized, leading to a gate-tunable crossover from weak localization to antilocalization. The necessary theory of 2D magnetotransport in the presence of spin-orbit coupling beyond the diffusive approximation is developed and used to analyze experimental data. With this theory the Rashba contribution and linear and cubic Dresselhaus contributions to spin-orbit coupling are separately estimated, allowing the angular dependence of spin-orbit precession to be extracted at various gate voltages.

Spin-orbit coupling, antilocalization, and parallel magnetic fields in quantum dots

We investigate antilocalization due to spin-orbit coupling in ballistic GaAs quantum dots. Antilocalization that is prominent in large dots is suppressed in small dots, as anticipated theoretically. Parallel magnetic fields suppress both antilocalization and also, at larger fields, weak localization, consistent with random matrix theory results once orbital coupling of the parallel field is included. In situ control of spin-orbit coupling in dots is demonstrated as a gate-controlled crossover from weak localization to antilocalization.

The effects of payback and loan repayment programs on medical student career plans

Many states have considered implementing payback programs on state-subsidized medical education to increase the rate of graduates returning to those states to practice. An alternative is for states to offer and expand loan repayment programs to entice medical school graduates from rural states to return to their home states. The goal of this study is to determine and contrast the impact these two types of programs might have on medical school choice and students' intentions to return to their home states. Two hundred twenty-nine medical students were surveyed (response rate 80 percent). The questionnaire collected background information on the students and addressed the possible impact of payback and loan repayment policy proposals on student plans. Forty-seven percent of students reported that they would attend a different medical school if a required payback program were in place. Students who were more competitive at the time of admission to medical school were significantly more likely to say they would attend another medical school than were less competitive students. In contrast, 48 percent of students reported that they would be more likely to return to their home states if expanded loan repayment programs were available for service in areas of need. The findings suggest that payback programs may dissuade more competitive students from entering medical schools with such requirements, compromising the pool of students most likely to return to rural areas. Conversely, medical students appear willing to consider loan repayment programs upon completion of their training.

Quantitative amino acid analysis using a Beckman system gold HPLC 126AA analyzer

BACKGROUND

The Beckman 6300/7300 analyzer, which was widely used for amino acid (AA) analysis, is no longer commercially available.

METHODS

To set up an affordable AA analysis program, a Beckman system gold HPLC 126AA analyzer and Pickering Laboratories reagents were used. Two quantitative AA analysis programs were developed. One was an 18-min short program quantitating seven AAs from plasma and dried blood spots (DBS) specimens using Lithium eluents Li-365 and Li-375 at 70 degrees C column temperature. The short program could be used for diagnosis and follow-up dietary management for phenylketonuria (PKU), maple syrup urine disease (MSUD), tyrosinemia and homocystinuria patients. The second program was a 118-min long AA screening panel quantitating 40 AAs using Lithium eluents Li-275, Li-365 and Li-375 at 32, 48 and 72 degrees C column temperatures from plasma and urine specimens.

RESULTS

The values obtained from DBS specimens were in good agreement with certified results from the Centers for Disease Control and Prevention. The values obtained from plasma and urine samples were in good correlation with those obtained from Beckman 6300 analyzer (0.9076 < or = r < or = 0.999).

CONCLUSIONS

Amino acid quantitation from physiological samples using a Beckman 126AA Analyzer and Pickering Laboratories reagents was useful for clinical diagnosis and monitoring of aminoacidopathies.

A longitudinal study of salivary sialic acid in preterm infants: Comparison of human milk-fed versus formula-fed infants

We found that the saliva of preterm infants fed human milk contains twice the level of sialic acid as that in infants fed commercial formulas. The higher sialic acid level suggests greater viscosity and enhanced protection of the mucosal surfaces in breast-fed infants. Human milk itself is a rich source of sialylated oligosaccharides.

Pro- and anti-apoptotic members of the Bcl-2 family in skeletal muscle: a distinct role for Bcl-2 in later stages of myogenesis

Apoptotic myonuclei appear during myogenesis and in diseased muscles. To investigate cell death regulation in skeletal muscle, we examined how members of the Bcl-2 family of apoptosis regulators are expressed and function in the C2C12 muscle cell line and in primary muscle cells at different stages of development. Both anti-apoptotic (Bcl-W, Bcl-X(L)) and pro-apoptotic (Bad, Bak, Bax) members of the Bcl-2 family were expressed in developing skeletal muscle in vivo. Each was also expressed in embryonic (E11-12), fetal (E15-16), and neonatal muscle stem cells, myoblasts, and myotubes in vitro. In contrast, Bcl-2 expression was limited to a small group of mononucleate, desmin-positive, myogenin-negative muscle cells that were seen in fetal and neonatal, but not embryonic, muscle cell cultures. The cell surface protein Sca-1, which is associated with muscle and blood stem cells, was found on approximately 1/2 of these Bcl-2-positive cells. Loss of Bcl-2 did not affect expression of other family members, because neonatal muscles of wild-type and Bcl-2-null mice had similar amounts of Bcl-X(L), Bcl-W, Bad, Bak, and Bax mRNAs. Loss of Bcl-2 did have functional consequences; however, because neonatal muscles of Bcl-2-null mice had only approximately 2/3 as many fast muscle fibers as muscles in wild-type mice. Thus, Bcl-2 function is required for particular stages of fetal and postnatal myogenesis.

Changes in serum thyroxine and thyroid-stimulating hormone concentrations in epileptic dogs receiving phenobarbital for one year

A multicentric prospective study was conducted to monitor the effect of phenobarbital on serum total thyroxine (T4) and thyroid-stimulating hormone (TSH) concentrations in epileptic dogs. Serum T4 concentrations were determined for 22 epileptic dogs prior to initiation of phenobarbital therapy (time 0), and 3 weeks, 6 months, and 12 months after the start of phenobarbital. Median T4 concentration was significantly lower at 3 weeks and 6 months compared to time 0. Thirty-two percent of dogs had T4 concentrations below the reference range at 6 and 12 months. Nineteen of the 22 dogs had serum TSH concentrations determined at all sampling times. A significant upward trend in median TSH concentration was found. No associations were found between T4 concentration, dose of phenobarbital, or serum phenobarbital concentration. No signs of overt hypothyroidism were evident in dogs with low T4, with one exception. TSH stimulation tests were performed on six of seven dogs with low T4 concentrations at 12 months, and all but one had normal responses. In conclusion, phenobarbital therapy decreased serum T4 concentration but did not appear to cause clinical signs of hypothyroidism. Serum TSH concentrations and TSH stimulation tests suggest that the hypothalamic-pituitary-thyroid axis is functioning appropriately.

Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets

Both anthropologists and nutritionists have long recognized that the diets of modern-day hunter-gatherers may represent a reference standard for modern human nutrition and a model for defense against certain diseases of affluence. Because the hunter-gatherer way of life is now probably extinct in its purely un-Westernized form, nutritionists and anthropologists must rely on indirect procedures to reconstruct the traditional diet of preagricultural humans. In this analysis, we incorporate the most recent ethnographic compilation of plant-to-animal economic subsistence patterns of hunter-gatherers to estimate likely dietary macronutrient intakes (% of energy) for environmentally diverse hunter-gatherer populations. Furthermore, we show how differences in the percentage of body fat in prey animals would alter protein intakes in hunter-gatherers and how a maximal protein ceiling influences the selection of other macronutrients. Our analysis showed that whenever and wherever it was ecologically possible, hunter-gatherers consumed high amounts (45-65% of energy) of animal food. Most (73%) of the worldwide hunter-gatherer societies derived >50% (> or =56-65% of energy) of their subsistence from animal foods, whereas only 14% of these societies derived >50% (> or =56-65% of energy) of their subsistence from gathered plant foods. This high reliance on animal-based foods coupled with the relatively low carbohydrate content of wild plant foods produces universally characteristic macronutrient consumption ratios in which protein is elevated (19-35% of energy) at the expense of carbohydrates (22-40% of energy).

Coding sequence, chromosomal localization, and expression pattern of Nrf1: the mouse homolog of Drosophila erect wing

In Drosophila, the erect wing (ewg) protein is required for proper development of the central nervous system and the indirect flight muscles. The fly ewg gene encodes a novel DNA-binding domain that is also found in four genes previously identified in sea urchin, chicken, zebrafish, and human. To identify mouse ewg homologs, we designed degenerate primers to the conserved DNA-binding domain. The RT-PCR product obtained from mRNA of the mouse muscle cell line C2C12 was used to screen cDNA libraries; a single gene was identified which encodes a predicted 503 amino acid protein. The mouse ewg homolog, termed Nrf1, was mapped to proximal Chr 6. By RT-PCR and Northern analysis, Nrf1 was expressed in all tissues examined, and Northern analysis on adult tissues revealed a complex banding pattern suggesting extensive alternative splicing. Nrf1 hybridized to mRNA transcripts at approximately 2.2 kb, 4.0 kb, 4.4 kb, and 5.0 kb, with additional tissue-specific transcripts at 1.5 kb in testis, 1.9 kb in lung, and 3.7 kb in skeletal muscle. In situ hybridization on whole-mount E9-10.5 embryos showed a broad pattern of expression, with the highest levels of expression in the central nervous system, somites, first branchial arch, optic vesicle, and otic vesicle.

Arylsulfatase A pseudodeficiency: altered kinetic and heat-inactivation properties

Arylsulfatase A (ASA) pseudodeficiency (PD) was described in clinically healthy individuals with ASA-deficient activity. To confirm that the PD individual in the present study is homozygous for the PD allele without any other mutations, direct solid-phase sequencing was done and the two A-to-G transitions--one at the third N-glycosylation site (N350S) and the other at the first polyadenylation signal (ATTAAC to AGTAAC)--were identified. No other mutations were detected in the entire coding region nor in the intron-exon boundary region of the ASA gene in the PD cells. Kinetic studies to compare the partially purified ASA from controls to that from a homozygote (PD allele) were carried out using p-nitrocatechol sulfate (p-NCS) as a substrate. The apparent Km for the control ASA was 0.6 mM and for the PD enzyme 2.0 mM (p < 0.01). The heat inactivation at 60 degrees C revealed 50% inactivation within 90 min for control ASA and 28 min for PD ASA. At 65 degrees C, the 50% inactivation was reached at 18 min for the control and at 8.5 min for the PD. These results document the decreased affinity of ASA toward p-NCS and increased heat inactivation from a PD individual. Western blot analysis following SDS-PAGE and isoelectric focusing revealed differences in both the molecular weight and the isoelectric point between the control ASA and that of the PD allele. To the best of our knowledge, this is the first report showing the altered properties of ASA from a PD homozygote.

Effects of phenobarbital treatment on serum thyroxine and thyroid-stimulating hormone concentrations in epileptic dogs

OBJECTIVE

To determine whether phenobarbital treatment of epileptic dogs alters serum thyroxine (T4) and thyroid-stimulating hormone (TSH) concentrations.

DESIGN

Cross-sectional study.

ANIMALS

78 epileptic dogs receiving phenobarbital (group 1) and 48 untreated epileptic dogs (group 2).

PROCEDURE

Serum biochemical analyses, including T4 and TSH concentrations, were performed for all dogs. Additional in vitro analyses were performed on serum from healthy dogs to determine whether phenobarbital in serum interferes with T4 assays or alters free T4 (fT4) concentrations.

RESULTS

Mean serum T4 concentration was significantly lower, and mean serum TSH concentration significantly higher, in dogs in group 1, compared with those in group 2. Thirty-one (40%) dogs in group 1 had serum T4 concentrations less than the reference range, compared with 4 (8%) dogs in group 2. All dogs in group 2 with low serum T4 concentrations had recently had seizure activity. Five (7%) dogs in group 1, but none of the dogs in group 2, had serum TSH concentrations greater than the reference range. Associations were not detected between serum T4 concentration and TSH concentration, age, phenobarbital dosage, duration of treatment, serum phenobarbital concentration, or degree of seizure control. Signs of overt hypothyroidism were not evident in dogs with low T4 concentrations. Addition of phenobarbital in vitro to serum did not affect determination of T4 concentration and only minimally affected fT4 concentration.

CONCLUSIONS AND CLINICAL RELEVANCE

Clinicians should be aware of the potential for phenobarbital treatment to decrease serum T4 and increase TSH concentrations and should use caution when interpreting results of thyroid tests in dogs receiving phenobarbital.

Coding sequence, genomic organization, chromosomal localization, and expression pattern of the signalosome component Cops2: the mouse homologue of Drosophila alien

The Drosophila alien gene is highly homologous to the human thyroid receptor interacting protein, TRIP15/COPS2, which is a component of the recently identified signalosome protein complex. We identified the mouse homologue of Drosophila alien through homology searches of the EST database. We found that the mouse cDNA encodes a predicted 443-amino-acid protein, which migrates at approximately 50 kDa. The gene for the mouse alien homologue, named Cops2, includes 12 coding exons spanning approximately 30 kb of genomic DNA on the central portion of mouse chromosome 2. Mouse Cops2 is widely expressed in embryonic, fetal, and adult tissues beginning as early as E7.5. Mouse Cops2 cDNA hybridizes to two mRNA bands in all tissues at approximately 2.3 and approximately 4 kb, with an additional approximately 1.9-kb band in liver. Immunostaining of native and epitope tagged proteins localized the mouse Cops2 protein in both the cytoplasm and the nucleus, with larger amounts in the nucleus in some cells.

Modulation of the baboon (Papio anubis) uterine endometrium by chorionic gonadotrophin during the period of uterine receptivity

This study was undertaken to determine the modulation of uterine function by chorionic gonadotrophin (CG) in a nonhuman primate. Infusion of recombinant human CG (hCG) between days 6 and 10 post ovulation initiated the endoreplication of the uterine surface epithelium to form distinct epithelial plaques. These plaque cells stained intensely for cytokeratin and the proliferating cell nuclear antigen. The stromal fibroblasts below the epithelial plaques stained positively for alpha-smooth muscle actin (alphaSMA). Expression of alphaSMA is associated with the initiation of decidualization in the baboon endometrium. Synthesis of the glandular secretory protein glycodelin, as assessed by Western blot analysis, was markedly up-regulated by hCG, and this increase was confirmed by immunocytochemistry, Northern blot analysis, and reverse transcriptase-PCR. To determine whether hCG directly modulated these uterine responses, we treated ovariectomized baboons sequentially with estradiol and progesterone to mimic the hormonal profile of the normal menstrual cycle. Infusion of hCG into the oviduct of steroid-hormone-treated ovariectomized baboons induced the expression of alphaSMA in the stromal cells and glycodelin in the glandular epithelium. The epithelial plaque reaction, however, was not readily evident. These studies demonstrate a physiological effect of CG on the uterine endometrium in vivo and suggest that the primate blastocyst signal, like the blastocyst signals of other species, modulates the uterine environment prior to implantation.

Seeking muscle stem cells

Skeletal muscle development requires the formation of myoblasts that can fuse with each other to form multinucleate myofibers. Distinct primary and secondary, slow and fast, populations of myofibers form by the time of birth. At embryonic, fetal, and perinatal stages of development, temporally distinct lineages of myogenic cells arise and contribute to the formation of these multiple types of myofibers. In addition, spatially distinct lineages of myogenic cells arise and form the anterior head muscles, limb (hypaxial) muscles, and dorsal (epaxial) muscles. There is strong evidence that myoblasts are produced from muscle stem cells, which are self-renewing cells that do not themselves terminally differentiate but produce progeny that are capable of becoming myoblasts and myofibers. Muscle stem cells, which may be multipotent, appear to be distinguishable from myoblasts by a number of indirect and direct criteria. Muscle stem cells arise either in unsegmented paraxial mesoderm (anterior head muscle progenitors) or in segmented mesoderm of the somites (epaxial and hypaxial muscle progenitors). These initial stages of myogenesis are regulated by positive and negative signals, including Wnt, BMP, and Shh family members, from nearby notochord, neural tube, ectoderm, and lateral mesoderm tissues. The formation of skeletal muscles, therefore, depends on the generation of spatially and temporally distinct lineages of myogenic cells. Myogenic cell lineages begin with muscle stem cells which produce the myoblasts that fuse to form myofibers.

Surface and gradiometer coils near a conducting body: the lift-off effect

The use of surface coils in magnetic resonance is widespread. Examples include MRI, detection of subsurface aquifers by NMR, and, more recently, landmine detection by nuclear quadrupole resonance. In many of these cases a finite-sized sample to be examined is contained within a larger medium that is a poor electrical conductor, and eddy currents induced by the RF fields provide a loss mechanism that reduces the effective quality factor Q of the transmitter and receiver coils. Here the losses induced in a circular surface coil (a horizontal loop antenna) separated a distance from a dissipative medium are calculated and compared to measurements. It is shown that often the overall efficiency of the coil for magnetic resonance can be improved by displacing the coil away from the conducting medium a prescribed "lift-off" distance. The use of a gradiometer as a surface coil is also examined, and it is shown by theory and experiment that in certain circumstances such a gradiometer can be more efficient than a conventional surface coil for inspection of conducting media.

Bcl-2 expression identifies an early stage of myogenesis and promotes clonal expansion of muscle cells

We show that Bcl-2 expression in skeletal muscle cells identifies an early stage of the myogenic pathway, inhibits apoptosis, and promotes clonal expansion. Bcl-2 expression was limited to a small proportion of the mononucleate cells in muscle cell cultures, ranging from approximately 1-4% of neonatal and adult mouse muscle cells to approximately 5-15% of the cells from the C2C12 muscle cell line. In rapidly growing cultures, some of the Bcl-2-positive cells coexpressed markers of early stages of myogenesis, including desmin, MyoD, and Myf-5. In contrast, Bcl-2 was not expressed in multinucleate myotubes or in those mononucleate myoblasts that expressed markers of middle or late stages of myogenesis, such as myogenin, muscle regulatory factor 4 (MRF4), and myosin. The small subset of Bcl-2-positive C2C12 cells appeared to resist staurosporine-induced apoptosis. Furthermore, though myogenic cells from genetically Bcl-2-null mice formed myotubes normally, the muscle colonies produced by cloned Bcl-2-null cells contained only about half as many cells as the colonies produced by cells from wild-type mice. This result suggests that, during clonal expansion from a muscle progenitor cell, the number of progeny obtained is greater when Bcl-2 is expressed.

Noise-immune coil for unshielded magnetic resonance measurements

A modified split-loop resonator that is electrically balanced and that has no magnetic dipole moment is shown to be relatively immune to environmental noise. Using a magnetic resonance surface coil of this design for 14N NQR at 3.4 MHz, it is demonstrated that magnetic resonance measurements can be made in the laboratory without additional RF shielding and with less than a 2 dB increase in the rms noise. Compared to more traditional designs, the modified split-loop resonator showed a net 17-dB gain in sensitivity for unshielded measurements. Copyright 1998 Academic Press.

The effect of dehydroepiandrosterone combined with a low-fat diet in spontaneously obese dogs: a clinical trial

Dehydroepiandrosterone (DHEA) has been shown to have antiobesity activity in rodents and spontaneously obese dogs. This study evaluated the effect of DHEA or placebo combined with a low-fat/high-fiber diet in spontaneously obese dogs in a clinical trial. Spontaneously obese, euthyroid dogs, referred to the University of Wisconsin School of Veterinary Medicine for treatment of their obesity, were evaluated for percent overweight, rate of weight loss, serum cholesterol, plasma lipoprotein and serum biochemistry profiles, complete blood count, and endocrine profiles (T4, T3, cortisol, insulin, and DHEA-sulfate). DHEA-treated dogs had a significantly increased rate of actual and percent excess weight loss compared with placebo-treated dogs. Serum cholesterol decreased in both treatment groups; however, DHEA-treated dogs had a significantly greater reduction than placebo-treated dogs. DHEA-treated dogs had a significant 32% reduction in total plasma cholesterol, which was due to a 27% reduction in the lipoprotein fraction containing the high-density lipoprotein (HDL) and a 50% reduction in the lipoprotein fraction containing the low-density lipoprotein (LDL). Placebo-treated dogs did not have a significant reduction in total plasma cholesterol or in the fraction containing LDL; however, they did have a significant 11% reduction in the fraction containing HDL. Significant decreases in serum T4 and T3 observed in dogs receiving DHEA were not noted in dogs receiving placebo. DHEA in combination with caloric restriction results in a faster rate of weight loss than does caloric restriction alone. In addition, DHEA has hypocholesterolemic activity, particularly affecting the lipoprotein fraction containing the LDL cholesterol.

Sialic acid concentration of brain gangliosides: variation among eight mammalian species

Sialic acid is a vital component of brain gangliosides which play an essential role in the transmission and storage of information in the brain. The concentration of bound sialic acid in gangliosides and free sialic acid in the brain cortex of eight different mammals [human, chimpanzee (Pan troglodytes), rat (Rattus norvegicus), mouse (Mus musculus), rabbit (Oryctolagus cuniculus), sheep (Ovis aries), cow (Bos indicus) and pig (Sus scrofa)] were compared. Total sialic acid concentration (890+/-103 microg/g wet weight tissue, mean+/-SE, n = 6) was 2-4 times higher in the human brain compared with the other species studied (0.001 < p < 0.05). There was no significant difference between human males and females. The rank order of adult brain sialic acid after humans (in microg/g) was rat (493+/-23, n = 12), mouse (445+/-29, n = 16), rabbit (380+/-18, n = 6), sheep (323+/-43, n = 6), cow (304+/-14, n = 6) and pig (252+/-14, n = 6). Apart from the cow vs the sheep, the differences between species were statistically significant (p < 0.05). In the mouse, cow and sheep, total sialic acid concentration increased during maturation by 18-32% (p < 0.05). In a 2-year-old chimpanzee, the sialic acid concentration in the left lobe of the brain cortex was 25% higher than that of right lobe at 6 weeks of age (p < 0.05). Free sialic acid was higher in the human brain cortex (41+/-3 microg/g) than that of the rat and mouse (32+/-3 and 25+/-5 microg/g respectively) and absent from other species. Variation in brain sialic acid concentration among different animals has implications for the evolution of the brain and may affect learning ability in animals.

Human milk oligosaccharides: only the breast

Over 100 years ago it was first deduced that a major component of human milk must be an unidentified carbohydrate that was not found in cows milk. At first this was thought to be a form of lactose and was called gynolactose. We now know that this was not a single carbohydrate but a complex mixture of approximately 130 different oligosaccharides. Although small amounts of a few oligosaccharides have been found in the milk of other mammals, this rich diversity of sugars is unique to human milk. The oligosaccharide content of human milk varies with the infant's gestation, the duration of lactation, diurnally and with the genetic makeup of the mother. Milk oligosaccharides have a number of functions that may protect the health of the breast fed infant. As they are not digested in the small intestine, they form the 'soluble' fibre of breast milk and their intact structure is available to act as competitive ligands protecting the breast-fed infant from pathogens. There is a growing list of pathogens for which a specific oligosaccharide ligand has been described in human milk. They are likely to form the model for future therapeutic and prophylactic anti-microbials. They provide substrates for bacteria in the infant colon and thereby contribute to the difference in faecal pH and faecal flora between breast and formula-fed infants. They may also be important as a source of sialic acid, essential for brain development.

MRF4 can substitute for myogenin during early stages of myogenesis

MRF4, myogenin, MyoD, and Myf-5 are the four members of the basic helix-loop-helix family of muscle-specific regulatory factors (MRFs). We examined whether MRF4 could substitute for myogenin in vivo by determining if the myofiber- and MRF4-deficient phenotype of myogenin (-/-) mice could be rescued by a myogenin promoter-MRF4 transgene. When the transgene was expressed at a physiological level in myogenin-deficient fetuses, we found that expression of the endogenous MRF4 gene was restored to normal levels, whereas MyoD levels were unchanged. Thus, MRF4 can participate in a positive autoregulatory loop and can substitute for myogenin to activate its own promoter. Myogenin-deficient fetuses that expressed the transgene also had more myosin, more and larger myofibers, and a more normal ribcage morphology than myogenin-deficient littermates without the transgene. The transgene failed, however, to restore normal numbers of myofibers or viability to myogenin-deficient mice, because the approximately 1.6 kb myogenin promoter fragment was not expressed in most late-forming myofibers. These results demonstrate that MRF4 is able to substitute for myogenin to activate MRF4 expression and promote myofiber formation during the early stages of myogenesis.

Clinic nurses: confronting campus alcohol use on the frontline

Alcohol use is common on college campuses. Nurses in the student health clinic, in collaboration with other health professionals, have a responsibility and an opportunity to assess, intervene, and prevent problems related to the use of alcohol and other drugs. In this article, the author suggests how college health nurses, in everyday practice, can seize opportunities for helping students face their alcohol-related problems.

Acceleration of somitic myogenesis in embryos of myogenin promoter-MRF4 transgenic mice

The four muscle regulatory factors (MRFs) of the MyoD family are expressed in distinct temporal and spatial patterns in developing somites. To examine MRF function and regulation in somites, we generated myogenin promoter-MRF4 transgenic mice in which MRF4 was expressed in rostral somites about a half day earlier than normal. We found that the transgene, which was expressed at about the same level as endogenous MRFs, did not noticeably alter developing or adult mice, whereas the rostral somites of transgenic embryos showed accelerated myocyte formation, as well as precocious expression of the endogenous MRF4 gene. In an individual transgenic somite, MRF4 was expressed in both presumptive myotomal (mesenchymal) and dermatomal (epithelial) cells. Transgenic dermatomal cells also contained myogenin, which is expressed early in myogenesis, but did not contain myosin, which is expressed late in myogenesis. In transgenic myotomal cells, in contrast, precocious expression of MRF4 accelerated late events in myogenesis, including myosin expression and striated myofibril formation. MRF function, therefore, appears to be differentially regulated in dermatomal and myotomal cells.

Incidence of perioperative myocardial ischemia in TURP patients

STUDY OBJECTIVE

To determine the incidence of new episodes of myocardial ischemia in patients undergoing transurethral resection of the prostate (TURP).

DESIGN

Prospective, nonrandomized study.

SETTING

Veterans Administration medical center.

PATIENTS

39 patients undergoing elective TURP.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Myocardial ischemia was detected with a 3-channel ambulatory ECG recorded. The ambulatory ECG recorder was applied preoperatively and removed when the patient left the recovery room. New myocardial ischemia was defined as a 1 mm or greater ST depression or a 2 mm or greater ST elevation from baseline, lasting for 1 minute or longer in at least one lead at the J point plus 60 msec unless this point fell within the T wave, in which case the J point 40 msec or greater was used. ST changes consistent with myocardial ischemia were confirmed by a cardiologist blinded to the patient's clinical course. Seven of 39 TURP patients (18%) had ST segment changes indicative of new myocardial ischemia. These seven patients had more prostate tissue resected and more blood loss than the 32 patients who did not have any myocardial ischemia (p < 0.05).

CONCLUSIONS

Patients undergoing TURP have an 18% incidence of myocardial ischemia. Patients undergoing TURP with more prostate tissue resected and greater blood loss are at increased risk for perioperative myocardial ischemia.

Memory for conversation

Memory for conversation is treated as a source of coherence in social encounters and its connections with social competence are tested in a study of problem-solving conversations. As predicted, accurate recall is found to correlate positively with social competence and negatively with social anxiety. Partners have better memory for their own contributions than for each other's, and this difference is exacerbated by topic importance. Differences in recall are also found for differing amounts of involvement in the conversations. Results are explained in terms of resource allocation during conversation.

Progress, problems, and prospects for gene therapy in muscle

As the molecular defects that cause many muscle diseases have been identified, research has shifted to finding novel therapies. Gene therapy has been proposed both for correcting primary gene defects of muscle and as a way of using muscle for the production of proteins therapeutic in inflammatory or nonmuscle diseases. Several strategies have been developed to introduce foreign genes into diseased muscles, including myoblast transfer, direct injection of plasmids or DNA-liposome complexes, and infection with modified viruses. Related strategies, using antisense sequences or ribozymes, have been devised to modify gene expression in diseased cells. No method has yet proved itself in the clinic, although current work remains promising and some of the pitfalls that must be overcome have been identified.

The effect of insulin and insulin-like growth factors on luteal progesterone secretion in the rabbit

OBJECTIVE

The purpose of this study was to determine if insulin or insulin-like growth factors (IGF) either alone or in combination with estradiol (E2) could maintain progesterone secretion by rabbit luteal cells in culture.

METHODS

Progesterone secretion was measured in media of luteal cell cultures incubated in serum-free media alone or containing E2 with or without added insulin, IGF-I or IGF-II.

RESULTS

Progesterone production by rabbit luteal cells in culture fell precipitously in serum-free media containing E2, IGF-I, IGF-II, or insulin alone. However, when E2 was combined with insulin, IGF-I, or IGF-II, serum progesterone production was stimulated two- to fivefold above control levels.

CONCLUSION

There is an important synergism between insulin/IGF and E2 in regulating luteal steroidogenesis.