Sources of cosmic dust in the Earth's atmosphere.

There are four known sources of dust in the inner solar system: Jupiter Family comets, asteroids, Halley Type comets, and Oort Cloud comets. Here we combine the mass, velocity, and radiant distributions of these cosmic dust populations from an astronomical model with a chemical ablation model to estimate the injection rates of Na and Fe into the Earth's upper atmosphere, as well as the flux of cosmic spherules to the surface. Comparing these parameters to lidar observations of the vertical Na and Fe fluxes above 87.5 km, and the measured cosmic spherule accretion rate at South Pole, shows that Jupiter Family Comets contribute (80 ± 17)% of the total input mass (43 ± 14 t d-1), in good accord with Cosmic Background Explorer and Planck observations of the zodiacal cloud.

On the size and velocity distribution of cosmic dust particles entering the atmosphere.

The size and velocity distribution of cosmic dust particles entering the Earth's atmosphere is uncertain. Here we show that the relative concentrations of metal atoms in the upper mesosphere, and the surface accretion rate of cosmic spherules, provide sensitive probes of this distribution. Three cosmic dust models are selected as case studies: two are astronomical models, the first constrained by infrared observations of the Zodiacal Dust Cloud and the second by radar observations of meteor head echoes; the third model is based on measurements made with a spaceborne dust detector. For each model, a Monte Carlo sampling method combined with a chemical ablation model is used to predict the ablation rates of Na, K, Fe, Mg, and Ca above 60 km and cosmic spherule production rate. It appears that a significant fraction of the cosmic dust consists of small (<5 µg) and slow (<15 km s-1) particles.

Effect of estradiol and progesterone on metabolic biomarkers in healthy bitches.

The aim of this study was to evaluate the possible association between hormonal changes that occur during oestrus and biomarkers related with glucose metabolism (glucose and insulin), lipid metabolism (lipidic profile and BChE) and adipokines (adiponectin and ghrelin) in healthy bitches. For this purpose, we measured these analytes in serum of bitches, at two times: before (T1) and after (T2) the LH peak that were established according to progesterone concentrations. Increased levels of total cholesterol (p < 0.01), high density lipoprotein cholesterol (HDL-C) (p < 0.01), low density lipoprotein cholesterol (LDL-C) (p < 0.01), adiponectin (p < 0.01) and ghrelin (p < 0.05) were observed at T2 in comparison with T1. No statistically significant changes were observed in serum glucose, insulin, homoeostasis model assessment for insulin sensitivity (HOMA), triglycerides and BChE. When all data of T1 and T2 were pooled, serum adiponectin showed positive correlation with progesterone (r = 0.353; p = 0.022) and HDL-C (r = 0.307; p = 0.048), and negative with insulin (r = -0.429; p = 0.005), HOMA (r = -0.446; p = 0.003) and BChE (r = -0.522; p < 0.001). Ghrelin showed negative correlation with estradiol (r = -0.701; p = 0.004). BChE was negatively correlated with estradiol (r = -0.441; p = 0.018) and glucose (r = -0.343; p = 0.028), and positively with insulin (r = 0.460; p = 0.003) and HOMA (r = 0.505; p < 0.001). In conclusion, changes in metabolic biomarkers occur in bitches after LH peak, characterized by increased lipids (total cholesterol, HDL cholesterol and LDL cholesterol) without changes in BChE activity, and increased adiponectin and ghrelin concentrations, without significant changes in glucose and insulin.

Polymorphisms C677T and A1298C in the MTHFR gene in Mexican patients with rheumatoid arthritis treated with methotrexate: implication with elevation of transaminases.

Rheumatoid arthritis (RA) is the prototype of the rheumatic diseases worldwide. Methotrexate (MTX) is the drug of first choice in the treatment of this disease due to its immunosuppressant effect. However, side events are present in 30% of the patients. The C677T and A1298C polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) gene are involved in the metabolism of MTX. Earlier studies reported an association between these polymorphisms and elevation of hepatic enzymes. We analyzed the frequencies of both polymorphisms and the presence of transaminasemia in 70 Mexican patients with rheumatic arthritis treated with MTX. The 19% (13/70) of patients had an increase in the serum level of transaminases. The A1298C polymorphism was associated with elevation of transaminases (P=0.024). The identification of MTHFR genotypes for C677T and A1298C polymorphisms could lead clinicians to identify patients in risk of elevation of transaminases, and give them an individualized treatment, as is a goal of pharmacogenetics.

Effects of orchidectomy in selective biochemical analytes in Beagle dogs.

The objective of this study was to evaluate the possible effects of orchidectomy and associate hormonal changes on circulating concentrations of acute-phase proteins (APPs) (CRP--C-reactive protein; Hp--haptoglobin; Cp--ceruloplasmin), adiponectin and IGF-1 in dogs. For this, a total of five adult Beagle dogs were subjected to orchidectomy. Blood samples were taken before neutering, during six consecutive days and on weeks 2, 4, 8 and 12 after surgery. Appropriate diet regime was maintained to keep stable body weight of the dogs. Concentrations of APPs significantly increased on days 2-3 for CRP and 2-7 for Hp and Cp. On days 3-4 after neutering, adiponectin levels were significantly lower than before surgery (p<0.05 and <0.01, respectively). After this initial change, adiponectin did not show any significant alteration during the 3 months. Serum IGF-1 concentrations were significantly decreased at days 2-5 after neutering. In addition, on weeks 8 and 12 serum IGF-1 levels were significantly lower (p<0.001 and <0.01 respectively) in comparison with those before surgery. In conclusion, orchidectomy induced a short-term inflammatory process that was associated with the increase in serum levels of APPs and decrease in IGF-1 and adiponectin levels. However, orchidectomy did not result in long-term changes of circulating concentrations of APPs or adiponectin. Although a decrease in IGF-1 levels was recorded 2 months after surgery, possibly as a consequence of associated decrease in androgen levels or food restriction.

Meteoric Metal Chemistry in the Martian Atmosphere.

Recent measurements by the Imaging Ultraviolet Spectrograph (IUVS) instrument on NASA's Mars Atmosphere and Volatile EvolutioN mission show that a persistent layer of Mg+ ions occurs around 90 km in the Martian atmosphere but that neutral Mg atoms are not detectable. These observations can be satisfactorily modeled with a global meteoric ablation rate of 0.06 t sol-1, out of a cosmic dust input of 2.7 ± 1.6 t sol-1. The absence of detectable Mg at 90 km requires that at least 50% of the ablating Mg atoms ionize through hyperthermal collisions with CO2 molecules. Dissociative recombination of MgO+.(CO2)n cluster ions with electrons to produce MgCO3 directly, rather than MgO, also avoids a buildup of Mg to detectable levels. The meteoric injection rate of Mg, Fe, and other metals-constrained by the IUVS measurements-enables the production rate of metal carbonate molecules (principally MgCO3 and FeCO3) to be determined. These molecules have very large electric dipole moments (11.6 and 9.2 Debye, respectively) and thus form clusters with up to six H2O molecules at temperatures below 150 K. These clusters should then coagulate efficiently, building up metal carbonate-rich ice particles which can act as nucleating particles for the formation of CO2-ice clouds. Observable mesospheric clouds are predicted to occur between 65 and 80 km at temperatures below 95 K and above 85 km at temperatures about 5 K colder.

Regression models to predict the behavior of the coefficient of friction of AISI 316L on UHMWPE under ISO 14243-3 conditions.

Friction is the natural response of all tribosystems. In a total knee replacement (TKR) prosthetic device, its measurement is hindered by the complex geometry of its integrating parts and that of the testing simulation rig operating under the ISO 14243-3:2014 standard. To develop prediction models of the coefficient of friction (COF) between AISI 316L steel and ultra-high molecular weight polyethylene (UHMWPE) lubricated with fetal bovine serum dilutions, the arthrokinematics and loading conditions prescribed by the ISO 142433: 2014 standard were translated to a simpler geometrical setup, via Hertz contact theory. Tribological testing proceeded by loading a stainless steel AISI 316L ball against the surface of a UHMWPE disk, with the test fluid at 37 °C. The method has been applied to study the behavior of the COF during a whole walking cycle. On the other hand, the role of protein aggregation phenomena as a lubrication mechanism has been extensively studied in hip joint replacements but little explored for the operating conditions of a TKR. Lubricant testing fluids were prepared with fetal bovine serum (FBS) dilutions having protein mass concentrations of 5, 10, 20 and 36 g/L. The results were contrasted against deionized, sterilized water. The results indicate that even at protein concentration as low as 5 g/L, protein aggregation phenomena play an important role in the lubrication of the metal-on-polymer tribopair. The regression models of the COF developed herein are available for numerical simulations of the tribological behavior of the aforementioned tribosystem. In this case, surface stress rather than film thickness should be considered.

The coefficient of friction of UHMWPE along an entire walking cycle using a ball-on-disc tribometer under arthrokinematics and loading conditions prescribed by ISO 14243-3:2014.

The observation of tribological phenomena occurring in total knee replacement (TKR) simulators may be obscured by the intrinsic complexity of their operation: the dynamics and kinematics prescribed by the ISO 14243-3:2014 standard, and the geometry of the surfaces involved. On the other hand, evaluating the individual performance of the tribosystem elements may be carried out in simpler apparatuses. An experimental method is presented here, by means of which the arthrokinematics and loading conditions prescribed by the said standard are adapted to a ball-on-disc configuration in order to observe the behavior of the coefficient of friction along an entire walking cycle, using the contact point of an AISI 316L stainless steel ball rolling/sliding on an ultra-high molecular weight polyethylene (UHMWPE) disc, lubricated by a solution of fetal bovine serum, at 37°C. The method was tried on two different testing fluids prepared with protein concentrations of 20g/L, according to the said standard, and 36g/L, as received. The statistical model obtained for the behavior of the COF during the entire walking cycle may be used in numerical simulations of UHMWPE wear, under the conditions established by ISO 14243-3:2014.

A novel instrument to measure differential ablation of meteorite samples and proxies: The Meteoric Ablation Simulator (MASI).

On entering the Earth's atmosphere, micrometeoroids partially or completely ablate, leaving behind layers of metallic atoms and ions. The relative concentration of the various metal layers is not well explained by current models of ablation. Furthermore, estimates of the total flux of cosmic dust and meteoroids entering the Earth's atmosphere vary over two orders of magnitude. To better constrain these estimates and to better model the metal layers in the mesosphere, an experimental Meteoric Ablation Simulator (MASI) has been developed. Interplanetary Dust Particle (IDP) analogs are subjected to temperature profiles simulating realistic entry heating, to ascertain the differential ablation of relevant metal species. MASI is the first ablation experiment capable of simulating detailed mass, velocity, and entry angle-specific temperature profiles whilst simultaneously tracking the resulting gas-phase ablation products in a time resolved manner. This enables the determination of elemental atmospheric entry yields which consider the mass and size distribution of IDPs. The instrument has also enabled the first direct measurements of differential ablation in a laboratory setting.

Vagus nerve stimulation therapy for epilepsy in older adults.

The authors assessed the efficacy, safety, and tolerability of vagus nerve stimulation (VNS) for refractory epilepsy in 45 adults 50 years of age and older. They determined seizure frequency, adverse effects, and quality of life. At 3 months, 12 patients had a >50% decrease in seizure frequency; at 1 year, 21 of 31 studied individuals had a >50% seizure decrease. Side effects were mild and transient. Quality of life scores improved significantly with time.

Serologic survey of domestic animals for zoonotic arbovirus infections in the Lacandón Forest region of Chiapas, Mexico.

A serologic survey in domestic animals (birds and mammals) was conducted in four communities located in the Lacandón Forest region of northeastern Chiapas, Mexico, during June 29 to July 1, 2001, with the objective to identify zoonotic arboviruses circulating in this area. We collected 202 serum samples from healthy domestic chickens, geese, ducks, turkeys, horses and cattle. The samples were tested by plaque-reduction neutralization test for antibodies to selected mosquito-borne flaviviruses (family Flaviviridae), including St. Louis encephalitis (SLE), Rocio (ROC), Ilheus (ILH), Bussuquara (BSQ), and West Nile (WN) viruses, and selected alphaviruses (family Togaviridae), including Western equine encephalitis (WEE), Eastern equine encephalomyelitis (EEE), and Venezuelan equine encephalitis (VEE) viruses. Neutralizing antibodies to SLE virus were detected in two (8%) of 26 turkeys, 15 (23%) of 66 cattle, and three (60%) of five horses. Antibodies to VEE virus were detected in 29 (45%) of 65 cattle. Because some of these animals were as young as 2 months old, we demonstrated recent activity of these two viruses. Sub-typing of the VEE antibody responses indicated that the etiologic agents of these infections belonged to the IE variety of VEE, which has been reported from other regions of Chiapas. WN virus-neutralizing antibodies were detected in a single cattle specimen (PRNT(90) = 1:80) that also circulated SLE virus-neutralizing antibodies (PRNT(90) = 1:20), suggesting that WN virus may have been introduced into the region. We also detected weak neutralizing activity to BSQ virus in four cattle and a chicken specimen, suggesting the presence of this or a closely related virus in Mexico. There was no evidence for transmission of the other viruses (ROC, ILH, EEE, WEE) in the study area.

[Primary laryngeal tuberculosis caused by Mycobacterium bovis]. / Tuberculosis laríngea primaria por Mycobacterium bovis.

It is suggested that laryngeal tuberculosis is a common complication of pulmonary tuberculosis. The most frequent germ is Mycobacterium tuberculosis. We present a case in which a infrequent bacillus, Mycobacterium bovis, was isolated without lung afectation. Considerations about morphologic and microbiologic findings are discussed.

High temperature stability of anatase in titania-alumina semiconductors with enhanced photodegradation of 2, 4-dichlorophenoxyacetic acid.

The incorporation of aluminum acetylacetonate as alumina source during the gelation of titanium alkoxide reduces the nucleation sites for the formation of large rutile crystals on temperatures ranging from 400 to 800°C. As a result, the aggregation of anatase crystals is prevented at high temperature. A relationship among the specific surface area, pore size, energy band gap, crystalline structure and crystallite size as the most relevant parameters are evaluated and discussed. According to the results for the photocatalytic degradation of 2,4-dichlorophenoxyacetic acid, the specific surface area, pore size, Eg band gap are not determinant in the photocatalytic properties. It was found that the anatase crystallite size is the mores important parameter affecting the degradation efficiency.

Intramolecular Friedel-Crafts-type reactions involving N-acyliminium ions derived from glycine templates.

Enantiomerically pure 4-substituted 2-aralkyl-2,4-dihydro-1H-pyrazino[2,1-b]quinazoline-3,6-diones (1b-m) in which the alkyl chain is (CH(2))(n), n = 1-3, behave as glycine templates giving by treatment with [hydroxy(tosyloxy)iodo]benzene in ethyl acetate cis-1-tosyloxy derivatives. When these compounds contain electron-rich aryl substituents with n = 2, they spontaneously cyclize through intramolecular Friedel-Crafts-type diastereoselective reactions to give penta- or hexacyclic compounds. Otherwise, they give by solvolysis cis-1-alkoxy derivatives, which in a second step, may be cyclized in acid if n = 2, 3. All these reactions must occur through N-acyliminium species in S(N)1-like mechanisms. 1-Alkoxy-2-arylmethyl derivatives are reluctant to cyclize, giving trans-1-hydroxy compounds as the only isolated reaction products.

Risperidone in the treatment of choreiform movements and aggressiveness in a child with "PANDAS".

The acronym 'PANDAS' (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections) is used to describe neuropsychiatric symptoms putatively resulting from autoimmune responses to streptococcal infection in vulnerable children. A case of 'PANDAS' is presented to increase physician awareness of this disorder and to document effectiveness of risperidone in chorea and treatment-resistant disruptive behavior associated with this syndrome. To our knowledge, this is the first case report on risperidone in pediatric chorea, although studies on effectiveness of this agent in Tourette's disorders have been previously published.

[Incidence of adverse reactions to additives. Our experience over 10 years]. / Incidencias de reacciones adversas con aditivos. Nuestra experiencia de 10 años.

No published information exists about the incidence of food additives reactions in the general population. Most studies have been made in patients with urticaria and bronchial asthma. The majority of them lack an adequate design and, therefore, the reported results should be interpreted with extreme caution. In this article, we expose our ten years experience in this field. We have added up 1941 oral provocation tests, with an ample battery of additives, administering the tested substances directly or in aqueous or acid solution (1110 in patients with urticaria, mainly chronic urticaria, and 831 in asthmatic subjects, with or without aspirin intolerance). From these exhaustive data, we get the following conclusions: 1) in contrast with other-investigators, and using similar or even higher provocation doses, we get a very low incidence of adverse reactions. 2) We are sceptical that food additives play any role in chronic urticaria or in other cutaneous processes (only 0.63% provocation tests resulted in an urticarial exacerbation, and none of them was repeated after re-provocation). 3) In asthmatic patients, similar results were obtained, except with sulfites in acid solution challenge test (10% asthmatic exacerbations), possibly as a sign of nonspecific bronchial hyperreactivity. 4) The prescription of food additives free restrictive diets does not seem to be justified. The should be followed only by those patients with clear evidence of additives reactions. 5) In most cases, with punctual exceptions, the study of food additives reactions, in clinical allergy, implies a waste of time.

Stimulation of protooncogene expression by partial hepatectomy is not tissue-specific.

We have characterized the early protooncogene response and the later cell proliferative response in the kidneys and livers of normal rats cross-circulated with partially hepatectomized animals. Increase c-myc and C-Ha-ras expression was observed in the kidneys of totally hepatectomized rats, as well as those of their cross-circulated partners. This indicates that the initial response to hepatectomy is not organ-specific, although the later DNA synthetic response of the kidney is only approximately one-tenth that of regenerating liver. Expression of c-myc and c-Ha-ras is dramatically increased in the livers of both hepatectomized and nonhepatectomized, parabiotic (cross-circulated) rats within 1 hr of partial hepatectomy, confirming the presence of a circulating factor which stimulates protooncogene expression early in regeneration. DNA synthesis was also stimulated in the livers of the cross-circulated animals between 20 and 26 hr following hepatectomy, but only to a level one-eighth that of the livers of hepatectomized animals. Normal rats cross-circulated with totally hepatectomized animals also demonstrated an early increase in hepatic c-myc and c-Ha-ras expression, indicating that regeneration must be stimulated by an extrahepatic signal. Our data suggest that the early increase in protooncogene expression is a non-organ-specific response to partial hepatectomy which does not insure subsequent cellular proliferation. The organ specificity of liver regeneration must involve an event separate from the early stimulation of protooncogene expression.

Stimulation of renal and hepatic c-myc and c-Ha-ras expression by unilateral nephrectomy.

Unilateral nephrectomy induces compensatory hypertrophy of the contralateral kidney in rats, resulting in a 25% weight increase in 14 days. We have demonstrated that expression of the c-myc and c-Ha-ras protooncogenes is increased more than ten-fold in the contralateral kidney within 4 to 8 hr following unilateral nephrectomy in rats. The increased expression of these genes is analogous to the increased expression of c-myc and c-Ha-ras that occurs early in liver regeneration, preceding the first increase in DNA synthesis by at least 20 hr. In order to define the tissue specificity of the signals for compensatory renal hypertrophy, we also determined the early protooncogene response and the proliferative response in the liver of rats following unilateral nephrectomy. The expression of c-myc and c-Ha-ras was also increased (five- to ten-fold) in the livers of these animals. DNA synthesis was stimulated in the contralateral kidney at 26-30 hr following nephrectomy as measured by 3H thymidine incorporation, indicating a hyperplastic response to unilateral nephrectomy. However, there was no increase in DNA synthesis in the liver despite the dramatic increase in c-myc and c-Ha-ras expression. Our data suggest that the early increase in protooncogene expression in response to unilateral nephrectomy is stimulated by circulating signals that are not tissue-specific. Increased protooncogene expression in both kidney and liver following unilateral nephrectomy is an early response to the regenerative stimulus, but later signals must provide the tissue specificity necessary for regeneration and cellular proliferation.