Phase-matching-free ultrashort laser pulse characterization from a transient plasma lens

A phase-matching-free ultrashort pulse retrieval based on the defocusing of a laser-induced plasma is presented. In this technique, a pump pulse ionizes a rare gas providing a plasma lens whose creation time is ultrafast. A probe pulse propagating through this gas lens experiences a switch of its divergence. The spectrum of the diverging part, isolated by a coronograph, is measured as a function of the pump-probe delay, providing a spectrogram that allows for a comprehensive characterization of the temporal properties of the probe pulse. The method, called PI-FROSt for "plasma-induced frequency-resolved optical switching," is simple, is free of phase-matching constraints, and can operate in both self- and cross-referenced configurations at ultrahigh repetition rate in the whole transparency range of the gas. The assessment of the method demonstrates laser pulse reconstructions of high reliability in both near-infrared (NIR) and ultraviolet (UV) spectral ranges.

Characterizing the carrier-envelope phase stability of mid-infrared laser pulses by high harmonic generation in solids

We present a novel approach for measuring the carrier-envelope phase (CEP) stability of a laser source by employing the process of high harmonic generation (HHG) in solids. HHG in solids driven by few-cycle pulses is very sensitive to the waveform of the driving pulse, therefore enabling to track the shot-to-shot CEP fluctuations of a laser source. This strategy is particularly practical for pulses at long central wavelength up to the mid-infrared spectral range where usual techniques used in the visible or near-infrared regions are challenging to transpose. We experimentally demonstrate this novel tool by measuring the CEP fluctuations of a mid-infrared laser source centered at 9.5~μm.

High-field mid-infrared pulses derived from frequency domain optical parametric amplification

We present a novel, to the best of our knowledge, approach for scaling the peak power of mid-infrared laser pulses with few-cycle duration and carrier-to-envelope phase stabilization. Using frequency domain optical parametric amplification (FOPA), selective amplification is performed on two spectral slices of broadband pulses centered at 1.8 µm wavelength. In addition to amplification, the Fourier plane is used for specific pulse shaping to control both the relative polarization and the phase/delay between the two spectral slices of the input pulses. At the output of the FOPA, intrapulse difference frequency generation provides carrier-envelope phase stabilized two-cycle pulses centered at 9.5 µm wavelength with 25.5 µJ pulse energy. The control of the carrier-envelope phase is demonstrated through the dependence of high-harmonic generation in solids. This architecture is perfectly adapted to be scaled in the future to high average and high peak powers using picosecond ytterbium laser technologies.

Phase-matching-free pulse retrieval based on transient absorption in solids

In this paper, we introduce a pulse characterization technique that is free of phase-matching constraints, exploiting transient absorption in solids as an ultrafast optical switch. Based on a pump-probe setup, this technique uses pump pulses of sufficient intensity to induce the switch, while the pulses to characterize are probing the transmissivity drop of the photoexcited material. This enables the characterization of low-intensity ultra-broadband pulses at the detection limit of the spectrometer and within the transparency range of the solid. For example, by using zinc selenide (ZnSe), pulses with wavelengths from 0.5 to 20 μm can be characterized, denoting five octaves of spectral range. Using ptychography, we retrieve the temporal profiles of both the probe pulse and the switch. To demonstrate this approach, we measure ultrashort pulses from a titanium-sapphire (Ti-Sa) amplifier, which are compressed using a hollow core fiber setup, as well as infrared to mid-infrared pulses generated from an optical parametric amplifier (OPA). The characterized pulses are centered at wavelengths of 0.77, 1.53, 1.75, 4, and 10 μm, down to sub-two optical cycles duration, exceeding an octave of bandwidth, and with energy as low as a few nanojoules.

Spatial Properties of High-Order Harmonic Beams from Plasma Mirrors: A Ptychographic Study

Spatial properties of high-order harmonic beams produced by high-intensity laser-matter interactions carry rich information on the physics of the generation process, and their detailed understanding is essential for applications of these light beams. We present a thorough study of these properties in the case of harmonic generation from plasma mirrors, up to the relativistic interaction regime. In situ ptychographic measurements of the amplitude and phase spatial profiles of the different harmonic orders in the target plane are presented, as a function of the key interaction parameters. These measurements are used to validate analytical models of the harmonic spatial phase in different generation regimes, and to benchmark ultrahigh-order Maxwell solvers of particle-in-cell simulation codes.

[Intracranial hemorrhage and oral anticoagulants of patients treated between 2011 and 2013 at the Nancy Regional University Hospital]

OBJECTIVE

To perform a descriptive analysis of intracranial hemorrhages of patients treated with an antivitamin K (fluindione, acenocoumarol or warfarin) or a direct oral anticoagulant (dabigatran, rivaroxaban or apixaban) at the Nancy Regional University Hospital.

MATERIAL AND METHOD

The study period was from January 2011 to December 2013 and the computerized data (Programme de Médicalisation des Systèmes d'Information) of our hospital was accessed to identify the patients. Clinical data were obtained from the patients' files. Regional healthcare system was queried for reimbursement data.

RESULTS

Among the 157 identified cases of intracranial hemorrhage, 153 were related to antivitamin K, primarily fluindione (n=127), and only 4 to a direct oral anticoagulant (3 dabigatran and 1 rivaroxaban). During the same period, regional data indicated that 65,345 patients had had at least one reimbursement of antivitamin K and 20,983 patients one reimbursement of an oral direct anticoagulant. In our series, the most frequent intracranial hemorrhages were subdural hematoma (chronic in 65 cases, acute in 50 cases) and intraparenchymal hemorrhage (20 cases). The global mortality rate was 20.2% but varied with the site of hemorrhage. In multivariate analysis, the two risk factors of fatal outcome were coma on admission (OR 6.2; 95%CI: 2.6-15.0) and a history of previous intracranial hemorrhage (OR 13,4; 95% CI: 1,6-114,9).

CONCLUSION

During the 2011-2013 period, antivitamin K, especially fluindione, was the most frequently involved anticoagulants in intracranial hemorrhages with hospitalization at our Regional University Hospital. Coma on admission and a history of previous intracranial hemorrhage were the two main risk factors for fatal outcome.

Dark Matter Search Results from the PICO-60 C_{3}F_{8} Bubble Chamber

New results are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 52 kg of C_{3}F_{8} located in the SNOLAB underground laboratory. As in previous PICO bubble chambers, PICO-60 C_{3}F_{8} exhibits excellent electron recoil and alpha decay rejection, and the observed multiple-scattering neutron rate indicates a single-scatter neutron background of less than one event per month. A blind analysis of an efficiency-corrected 1167-kg day exposure at a 3.3-keV thermodynamic threshold reveals no single-scattering nuclear recoil candidates, consistent with the predicted background. These results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (WIMP)-proton spin-dependent cross section at 3.4×10^{-41}  cm^{2} for a 30-GeV c^{-2} WIMP, more than 1 order of magnitude improvement from previous PICO results.

Interaction of Ultraintense Laser Vortices with Plasma Mirrors

Laser beams carrying orbital angular momentum (OAM) have found major applications in a variety of scientific fields, and their potential for ultrahigh-intensity laser-matter interactions has since recently been considered theoretically. We present an experiment where such beams interact with plasma mirrors up to laser intensities such that the motion of electrons in the laser field is relativistic. By measuring the spatial intensity and phase profiles of the high-order harmonics generated in the reflected beam, we obtain evidence for the helical wavefronts of the high-intensity laser at focus, and study the conservation of OAM in highly nonlinear optical processes at extreme laser intensities. The physical effects determining the field mode content of the twisted harmonic beams are elucidated.

A robust viologen and Mn-based porous coordination polymer with two types of Lewis acid sites providing high affinity for H2O, CO2 and NH3

A water stable PCP with two kinds of Lewis acid sites, open Mn²⁺ cations and viologen, shows high affinity for H₂O, CO₂ and NH₃.

[A subacute dementia: Inflammatory cerebral amyloid angiopathy]

We report a case of inflammatory cerebral amyloid angiopathy (CAA) that led to rapid cognitive decline, seizures, visual hallucinations, hyperproteinorrachia and right hemispheric leukopathy. Brain biopsy gave the diagnosis of CAA. Although no inflammatory infiltrate was found in the biopsy sample, corticosteroids led to a regression of the radiological lesions without significant clinical improvement. CAA is a rare disease, defined by lesions of classical cerebral amyloid angiopathy and perivascular infiltrates in contact with the affected vessels. In cases of rapidly progressive dementia associated with leukopathy, inflammatory amyloid angiopathy should be considered as cognitive disorders may improve after immunosuppressive therapy.

An unusual case of delayed-type hypersensitivity to ceftriaxone and meropenem

Recent studies have demonstrated a low cross-reactivity between β-lactam antibiotics and carbapenems in IgE-mediated reactions. There are no studies on cross-reactivity of meropenem in patients with non-immediate hypersensitivity to cephalosporins. We describe a case of a 13-year-old male, admitted in Neurosurgery with a severe extradural empyema complicating frontal sinusitis, submitted to an emergent bifrontal craniotomy. A generalized maculopapular exanthema, fever and malaise, appeared by the 7th day of meningeal doses of ceftriaxone, clindamycin and vancomycin. Those were replaced by meropenem, with posterior worsening of the reaction and mucosal involvement. A new scheme with amikacin, metronidazole and linezolid was done with improvement. Skin prick, intradermal and patch tests to penicillins, ceftriaxone and meropenem were negative. Lymphocyte transformation test was positive to ceftriaxone and negative to meropenem.Non-immediate T cell mechanism seems to be involved. Diagnosis work-up couldn't exclude cross-reactivity between ceftriaxone and meropenem.

[Systematic implementation of transthoracic echocardiography, transesophageal echocardiography and 24-hour Holter ECG for the detection of cardiac sources of embolism in patients with stroke or transient ischemic attack. A retrospective study of 220 patients]

INTRODUCTION

Embolism of cardiac origin accounts for around 20% of ischemic strokes. ECG and transthoracic echocardiography (TTE) are commonly obtained during the evaluation of patient of ischemic stroke but specific indications for the transesophageal (TEE) echocardiography and 24-hour Holter ECG (Holter) remain uncertain.

OBJECTIVES

The aim of this study is to report the contribution of TTE, TEE and Holter performed as a routine during the evaluation of patients with ischemic stroke (IS) or transient ischemic attack (TIA).

METHODS

This is a retrospective single-center study of 220 patients hospitalized between 1st January 2007 and 31st December 2010 for a first IS or TIA.

RESULTS

One hundred and forty-three IS and 77 TIA are identified. The average age of patients was 66 years (18-88 years). TTE/TEE/24-hour Holter allowed the diagnosis of cardiac sources of embolism in 135 patents (61.3%). TTE/TEE identified potential source of cardiogenic embolism in 126 patients (52.2%). Twenty four-hour Holter ECG tracked supraventricular arrhythmia in 15 patients (6.7%), 9 (4%) which had non-contributory ultrasound assessment.

CONCLUSION

The systematic implementation of TTE/TEE/Holter is useful for identifying potential sources of cardiogenic embolism. The performance of TEE remains above the TTE. Holter should be recommended because it is a cost effective and non-invasive tool.

Optically controlled solid-density transient plasma gratings

A general approach for optically controlled spatial structuring of overdense plasmas generated at the surface of initially plain solid targets is presented. We demonstrate it experimentally by creating sinusoidal plasma gratings of adjustable spatial periodicity and depth, and study the interaction of these transient structures with an ultraintense laser pulse to establish their usability at relativistically high intensities. We then show how these gratings can be used as a "spatial ruler" to determine the source size of the high-order harmonic beams produced at the surface of an overdense plasma. These results open new directions both for the metrology of laser-plasma interactions and the emerging field of ultrahigh intensity plasmonics.

Bisphosphonates as a supplement to exercise to protect bone during long-duration spaceflight

We report the results of alendronate ingestion plus exercise in preventing the declines in bone mass and strength and elevated levels of urinary calcium and bone resorption in astronauts during 5.5 months of spaceflight.

INTRODUCTION

This investigation was an international collaboration between NASA and the JAXA space agencies to investigate the potential value of antiresorptive agents to mitigate the well-established bone changes associated with long-duration spaceflight.

METHODS

We report the results from seven International Space Station (ISS) astronauts who spent a mean of 5.5 months on the ISS and who took an oral dose of 70 mg of alendronate weekly starting 3 weeks before flight and continuing throughout the mission. All crewmembers had available for exercise a treadmill, cycle ergometer, and a resistance exercise device. Our assessment included densitometry of multiple bone regions using X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) and assays of biomarkers of bone metabolism.

RESULTS

In addition to pre- and post-flight measurements, we compared our results to 18 astronauts who flew ISS missions and who exercised using an early model resistance exercise device, called the interim resistance exercise device, and to 11 ISS astronauts who exercised using the newer advanced resistance exercise device (ARED). Our findings indicate that the ARED provided significant attenuation of bone loss compared with the older device although post-flight decreases in the femur neck and hip remained. The combination of the ARED and bisphosphonate attenuated the expected decline in essentially all indices of altered bone physiology during spaceflight including: DXA-determined losses in bone mineral density of the spine, hip, and pelvis, QCT-determined compartmental losses in trabecular and cortical bone mass in the hip, calculated measures of fall and stance computed bone strength of the hip, elevated levels of bone resorption markers, and urinary excretion of calcium.

CONCLUSIONS

The combination of exercise plus an antiresoptive drug may be useful for protecting bone health during long-duration spaceflight.

Assessment of asthma control: clinical, functional and inflammatory aspects

BACKGROUND

Asthma is a complex disease with numerous markers of severity/activity. Clinical assessment,functional parameters and inflammation biomarkers are the most used A correlation between them is difficult, as each one evaluates a particular aspect of the disease.

OBJECTIVE AND METHODS

To explore the possible association between asthma control, pulmonary function and inflammation in patients with asthma, consecutive asthmatics underwent simultaneous spirometry (measurement of FEV1), exhaled nitric oxide (eNO) evaluation and Asthma Control Test (ACTTM) questionnaire.

RESULTS

The study included 232 asthmatics (mean age: 37.48 years; 78.4%female): 43% had uncontrolled asthma (ACTTM < or = 19) with FEV1 mean values of 83.3% +/- 21.8; 48% partially controlled (ACTTM: 20-24) with FEV1 of 87.6% +/- 17; 9% complete control (ACTTM = 25) with FEV1 of 93.1 +/- 20.6. The relation ACTTM/FEV1 and ACTTM/FEF 25-75% was statistically significant (p = 0.001 and p = 0.034, respectively). Among patients with eNO < 35 ppb, 66% had FEV1 > 80% and 52% had ACTTM > 19. No association was found combining ACTTM/eNO or FEV1/eNO. A subgroup of 66 patients was evaluated twice.

CONCLUSION

An association was found between ACTTM and spirometry, with higher ACTTM scores reflecting less bronchial obstruction. The authors advise a combined approach in asthma follow-up, involving clinical aspects, functional parameters and inflammation biomarkers, although in some circumstances ACT could be a valid instrument to be used alone to assess control.

Prevalence of aeroallergen sensitization and increased exhaled nitric oxide values in schoolchildren of different socioeconomic status

BACKGROUND

Screening for allergic diseases allows an early diagnosis to be made, thus reducing socioeconomic burden and enhancing quality of life. We determined the prevalence of elevated exhaled nitric oxide (eNO) levels and sensitization to common airborne allergens in schoolchildren from different socioeconomic backgrounds.

MATERIAL AND METHODS

The study population comprised 271 children (136 boys) aged between 8 and 12 years in whom we applied skin prick tests and determined eNO levels.

RESULTS

Thirty-five percent of the children were identified as atopic. There was a significantly higher prevalence of atopy in boys (43% vs. 27%). Among the children with a high socioeconomic status, 37% were atopic, compared with 30% of those with a low socioeconomic status. We observed a significantly lower prevalence of pollen sensitization in children of lower socioeconomic status (10% vs. 20%). In the atopic group, 51% had elevated eNO levels, while in the nonatopic group this value was 4%. The mean (SD) eNO level was 33.4 (26.6) ppb in the atopic group and 11.9 (6.4) ppb in the nonatopic group. No differences were found for eNO values in terms of gender or socioeconomic status.

CONCLUSIONS

Our results emphasize the high prevalence of atopy in our population and suggest that determination of eNO levels could help to provide an early diagnosis. We also observed the following: (a) a significant difference in mean eNO values between atopic and nonatopic children; (b) a significantly lower prevalence of pollen sensitization in children of lower socioeconomic status; and (c) a higher prevalence of atopy in boys.

Relationship between osteopontin and vascular calcifications in type 2 diabetic patients

AIM

To measure circulating osteopontin levels in a cohort of type 2 diabetic patients and to determine whether osteopontin could be associated with lower limb arteries calcifications, either intimal (atherosclerotic) or medial (mediacalcinosis).

METHODS

Osteopontin was measured in 60 patients with type 2 diabetes who were subdivided in three groups: group 1 (n=19) was characterized by the absence of peripheral vascular calcifications on plain soft tissue radiograms; group 2 (n=18) presented intimal calcifications without mediacalcinosis; in group 3 (n=23), mediacalcinosis was the dominant pattern.

RESULTS

Osteopontin levels were significantly higher in patients with mediacalcinosis (558 ng/ml [140-2289], median [range]) than in subjects without vascular calcifications (337 [134-841], P = 0.024) or in individuals with intimal lesions (340 [140-1154], P = 0.05). No correlation was observed between osteopontin, glycaemic control or HOMA test results. Osteopontin was correlated with creatinine clearance (P = 0.037).

CONCLUSION

In type 2 diabetic patients, circulating levels of osteopontin were higher in the presence of medial calcifications than in subjects without vascular lesions or in individuals with calcifications limited to the intimal

Response of canine cutaneous epitheliotropic lymphoma to lomustine (CCNU): a retrospective study of 46 cases (1999-2004)

BACKGROUND

Epitheliotropic lymphoma (ELSA) is an uncommon cutaneous canine malignancy of T lymphocytes. A consensus regarding the therapeutic standard of care is lacking, warranting evaluation of chemotherapeutic agents traditionally employed against canine nodal lymphoma in the treatment of ELSA.

HYPOTHESIS

The purpose of this retrospective, multi-institutional study was to evaluate the efficacy of 1-(2-chloroethyl)-3-cyclohexyl-l-nitrosourea (CCNU) in the treatment of ELSA.

ANIMALS

Forty-six dogs with adequate follow-up and treatment response information.

METHODS

All cases were diagnosed histopathologically. Immunohistochemisty (CD3, CD79a) was performed on 42/46 samples.

RESULTS

Presenting skin lesions included generalized scales (25/46), plaques or nodules (22/46), mucocutaneous lesions (14/ 46), and corneal involvement (1/46). Lymph node involvement and Sézary syndrome were documented in 7 and 2 dogs, respectively. The median number of CCNU treatments was 4 (range, 1-11), with a median starting dose of 60 mg/m(2) (range, 30-95). Of the 46 dogs, 15 achieved complete remission, 23 achieved partial remission, 5 had stable disease, and 3 had progressive disease, for an overall response rate of 83%. The median number of treatments to achieve a response was 1 (range, 1-6). The overall median duration of response was 94 days (range, 22-282). Sixteen dose reductions were required because of neutropenia (10/46), thrombocytopenia (1/46), anemia (1/46), increased liver enzyme activity (3/46), or unspecified reasons (1/46).

CONCLUSIONS AND CLINICAL IMPLICATIONS

Given the high response rate and well tolerated protocol, prospective studies are warranted to investigate the utility of CCNU alone or in multi-agent protocols for the treatment of ELSA.

Les céphalées après ponction lombaire en pédiatrie générale : étude prospective multicentrique

PURPOSE

To investigate the frequency of post lumbar puncture headaches (PLPH) after diagnostic lumbar puncture (LP) and to search for influence factors.

PATIENTS AND METHODS

Conducted over 6 months into 8 paediatric services, the study concerned 2 to 15 years old children. The LP technic (cannula gauge, bevel orientation, child position, reinsertion of the stylet) was standardised. For each child questionnaires were filled with the parents 3 and 8 days after LP for inquiring headaches, postural characteristics, length and clinical consequences.

RESULTS

Among 84 charts, 71 were exploitable. PLPH were observed in 25% of children. The mean duration was 5.9 days, mean bed rest was 1.4 day and mean antalgic treatment 1.7 day. The frequency of PLPH was not significantly influenced by age and sex, neither by the qualification of the physician performing the LP. The frequency was significantly lower when LP execution was easy (19.6 vs. 46.7%; P < 0.05), and when the child had viral meningitis (8 vs. 34.8%; P < 0.05).

CONCLUSION

We have found a more important frequency of PLPH than in previous paediatric studies. Clinical consequences justify other researches to precise influence factors and reduce the frequency of this complication.

[Methadone poisoning in a 1-year-old child treated by continuous infusion of naloxone]

Methadone is a synthetic narcotic used in opioid dependent situations. Child intoxications are harmful, sometimes responsible for death.

CASE REPORT

An one-year-old infant was seen in the emergency room, two hours after accidental methadone ingestion. He presented with coma, myosis and respiratory depression. After intubation, symptoms disappeared with naloxone injection. For maintaining this child safe, naloxone was given by continuous infusion during 48 hours.

CONCLUSION

Patients, families and professionals should be informed of the risks of methadone intoxication. Owing to methadone long duration of action, initial injection of naloxone, the specific opioid antagonist, must be followed by continuous infusion.

Mechanisms of insulin resistance in cystic fibrosis

Cystic fibrosis (CF) is associated with a high incidence of diabetes. Studies evaluating causes of CF-related diabetes (CFRD) have consistently documented decreased insulin secretion. In patients with CFRD, insulin sensitivity has been documented to be decreased, but controversy exists in patients with normal or impaired glucose tolerance (IGT). We undertook this study 1) to reexplore insulin sensitivity in patients with IGT and 2) to evaluate potential mechanisms of insulin resistance in CF, including GLUT-4 translocation, elevation of serum cytokines, and free fatty acid (FFA) levels. We recruited nine CF subjects with impaired glucose tolerance (IGTCF) and nine age-, gender-, and body mass index-matched control volunteers. Each underwent a hyperinsulinemic euglycemic clamp (200 mU. m(-2). min(-1)) to measure insulin sensitivity. A muscle biopsy was obtained at maximal insulin stimulation for measure of GLUT-4 translocation with sucrose gradients. An oral glucose tolerance test and National Institutes of Health (NIH) clinical status scores were measured in all volunteers. We also measured tumor necrosis factor (TNF)-alpha levels and FFA in all subjects. Additionally, we report the results of TNF-alpha and FFA in 32 CF patients previously studied by our group. Results were that glucose disposal rate (GDR) was significantly lower in the CFIGT subjects than in controls, indicative of impaired insulin action. GLUT-4 translocation was impaired in CF and correlated with GDR. TNF-alpha levels were higher in all CF subjects than in controls and correlated with GDR. There was no difference in FFA between CF and control subjects. Modified NIH clinical status scores were inversely correlated with GDR and TNF-alpha levels. We conclude that IGTCF patients have decreased peripheral insulin sensitivity. Mechanisms include elevation of TNF-alpha and impaired translocation of GLUT-4.

Kinetic studies of guinea pig liver transglutaminase reveal a general-base-catalyzed deacylation mechanism

Guinea pig liver transglutaminase (TGase) reacts with 0.1 mM N-Cbz-L-Glu(gamma-p-nitrophenyl ester)Gly (5, prepared herein, K(M) = 0.02 mM) to undergo rapid acylation that can be followed spectrophotometrically at 400 nm (pH 7.0, 25 degrees C). Deacylation of the transiently formed thiolester acyl enzyme intermediate via catalytic aminolysis was studied in the presence of six primary amines of widely varying basicity (pK(NH+) = 5.6-10.5). Steady-state kinetic studies were performed to measure k(cat) and K(M) values for each amine substrate. A Brønsted plot constructed through the correlation of log(k(cat)/K(M)) and pK(NH+) for each amine substrate displays a linear free-energy relationship with a slope beta(nuc) = -0.37 +/- 0.08. The shallow negative slope is consistent with a general-base-catalyzed deacylation mechanism in which a proton is removed from the amine substrate during its rate-limiting nucleophilic attack on the thiolester carbonyl. Kinetic isotope effects were measured for four acceptor substrates (water, kie = 1.1 +/- 0.1; aminoacetonitrile, kie = 5.9 +/- 1.2; glycine methyl ester, kie = 3.4 +/- 0.7; N-Ac-L-lysine methyl ester, kie = 1.1 +/- 0.1) and are consistent with a proton in flight at the rate-limiting transition state. The active site general-base implicated by these kinetic results is believed to be His-334, of the highly conserved TGase Cys-His-Asp catalytic triad.

Effects of long-duration bed rest on structural compartments of m. soleus in man

Magnetic resonance imaging (MRI), histomorphometry and electron microscopy of muscle demonstrate that long-term exposure to actual or simulated weightlessness (including head down bed rest) leads to decreased volume of antigravity muscles in mammals. In muscles interbundle space is occupied by the connective tissue. Rat studies show that hindlimb unloading induces muscle fiber atrophy along with increase in muscle non-fiber connective tissue compartment. Beside that, usually 20% of the muscle fiber volume is comprised by non-contractile (non-myofibrillar) compartment. The aim of the present study was to compare changes in muscle volume, and in muscle fiber size with alterations in myofibrillar apparatus, and in connective tissue compartment in human m. soleus under conditions of 120 day long head down bed rest (HDBR).

Guinea pig liver transglutaminase: A modified purification procedure affording enzyme with superior activity in greater yield

Tissue transglutaminase purified from guinea pig livers has a very broad substrate specificity in comparison with other members of the transglutaminase family and therefore is useful for substrate analogue kinetic studies. Modifications made in our laboratory to the standard purification protocol (J. E. Folk and S. I. Chung, 1985, Methods Enzymol. 113, 358-364) have yielded a 28% increase in specific activity and 55% increase in overall yield, while reducing the number of steps to the purification. Herein we report some of the highest yields and specific activities for guinea pig liver transglutaminase found in the literature, as well as the use of lyophilization as a solution to the long-standing problem of enzyme stability during storage.

Acute unilateral visual loss due to a single intranasal methamphetamine abuse

An otherwise healthy 35 year old male with insulin-dependent diabetes mellitus (IDDM) presented himself three days after a single intranasal methamphetamine abusus. Directly upon awakening the day after the recreational use of this drug, he discovered an acute and severe visual loss of his right eye. This unilateral loss of vision was permanent and eventually lead to a pale and atrophic optic nerve head. The characteristics of this visual loss, together with the aspect of the optic nerve head was very similar to the classical non-arteritic ischemic optic neuropathy (NAION). We suggest a direct ischemic episode to the short posterior ciliary arteries due to this single intranasal abuse of methamphetamine as the underlying pathogenesis of this acute and permanent visual loss.

Collagen cross-link excretion during space flight and bed rest

Extended exposure to weightlessness results in bone loss. However, little information exists as to the precise nature or time course of this bone loss. Bone resorption results in the release of collagen breakdown products, including N-telopeptide and the pyridinium (PYD) cross-links, pyridinoline and deoxypyridinoline. Urinary pyridinoline and deoxypyridinoline are known to increase during bed rest. We assessed excretion of PYD cross-links and N-telopeptide before, during, and after long (28-day, 59-day, and 84-day) Skylab missions, as well as during short (14-day) and long (119-day) bed-rest studies. During space flight, the urinary cross-link excretion level was twice those observed before flight. Urinary excretion levels of the collagen breakdown products were also 40-50% higher, during short and long bed rest, than before. These results clearly show that the changes in bone metabolism associated with space flight involve increased resorption. The rate of response (i.e. within days to weeks) suggests that alterations in bone metabolism are an early effect of weightlessness. These studies are important for a better understanding of bone metabolism in space crews and in those who are bedridden.

Regional variation in vertebral bone density and trabecular architecture are influenced by osteoarthritic change and osteoporosis

STUDY DESIGN

The effects of age-related osteoarthritic disease and bone loss on cortical and trabecular bone density in the human spine were analyzed. Changes were quantified by a new method of computed quantitative radiography. Using this method, the relative losses of bone mineral from specific areas and the specific redistribution of bone within vertebrae as a function of age-related bone loss and osteoarthritic change were determined.

OBJECTIVES

To quantify the effects of age-related bone loss and osteoarthritic disease on cortical and trabecular density in the human spine by the use of a new method of computed quantitative radiography.

SUMMARY OF BACKGROUND DATA

To the authors' knowledge, osteoarthritic and age-related changes resulting in the relative loss of bone mineral from specific areas within vertebrae have never been quantitatively studied.

METHODS

Seventy-four vertebrae were obtained from 23 normal, human subjects at autopsy. Vertebral bodies were measured by dual-energy x-ray absorption, and then sectioned for analysis by computerized quantitative radiography. Attention was focused on overall bone density, regional cancellous bone density, and cortical bone density (anterior cortex, superior, and inferior endplates) for both mid-sagittal and para-sagittal sections. One hundred forty sections were so analyzed.

RESULTS

Quantitative radiography demonstrated previously undescribed, well defined patterns of cortical and trabecular architecture and bone density within vertebral bodies that were uniform among vertebrae, but strongly influenced by osteoarthritic change and bone loss. These changes were neither detected nor documented by dual-energy x-ray absorption.

CONCLUSIONS

Understanding the patterns of bone lose, and knowing how osteoarthritic change affects normal bone loss yields insight into the pathophysiology of the aging process and osteoarthritic disorders. Knowledge of the variations in density and microanatomy within vertebrae may improve techniques of internal fixation and designs of spinal implants, and may help to clarify the pathogenesis of clinical problems such as fractures.

Increased blood manganese in cirrhotic patients: relationship to pallidal magnetic resonance signal hyperintensity and neurological symptoms

Increasing evidence suggests that manganese deposition is responsible for the T1-weighted magnetic resonance imaging (MRI) signal hyperintensity consistently observed in pallidum of cirrhotic patients. However, the relationship between blood manganese and the etiology or severity of liver disease, as well as the neurological symptomatology in these patients, has not been well established. In the present study, blood manganese concentrations were measured by atomic absorption spectrometry together with MRI and neurological evaluation in 57 cirrhotic patients with various etiologies and severity of liver disease. Blood manganese concentrations were elevated in 67% of cirrhotic patients and were significantly higher in patients with previous portacaval anastomoses or transjugular intrahepatic portosystemic shunt (TIPS). Pallidal signal hyperintensity was observed in 88% of patients, and significant correlations were demonstrated between blood manganese and pallidal index (PI) (a measure of pallidal signal hyperintensity), as well as Child-Pugh score. Assessment of extrapyramidal symptoms using the Columbia rating scale revealed a significant incidence of tremor, rigidity, or akinesia in up to 89% of cirrhotic patients. However, there was no significant correlation between blood manganese and extrapyramidal symptoms, although severity of akinesia was significantly greater in Child-Pugh C patients. Extrapyramidal symptoms could result from a toxic effect of manganese on basal ganglia dopaminergic function. These findings further support a role for manganese in the etiology of pallidal MRI signal hyperintensity in patients with chronic liver disease.

Effects of spaceflight on bone mineralization in the rhesus monkey

We combined dual-photon absorptiometry, iliac crest histomorphometry, and backscattered electrons analysis to characterize bone mineralization effects of a spaceflight on young monkeys. Two 4- to 5-kg male rhesus monkeys (Macaca mulatta) were flown during a 11.5-day spaceflight that took place onboard Cosmos 2229 biosatellite (Bion 10). Vivarium (n = 4) and Earth-based chair (n = 4) control situations were studied for comparison. Flight monkeys exhibited lower values of iliac cancellous bone volume, associated with nonsignificantly thinner trabeculae. Bone mineralization rate and the proportion of trabecular bone surface involved in mineralization processes were found markedly reduced after spaceflight. Analysis of embedded sections by backscattered electrons imaging showed a nonsignificant shift to lower mineralization in the flight biopsies vs. postflight mock-up biopsies. These results were in accordance with dual-photon absorptiometry evaluations showing a tendency for decreased bone mineral content during flight and recovery thereafter. The ground simulation experiment performed on the same monkeys more than 1 mo after landing suggests that the observed effects were specifically related to spaceflight and that the animals had only partially recovered. Additional animals on future flights will be required to confirm these findings.