Preoperative MR Imaging to Differentiate Chordoid Meningiomas from Other Meningioma Histologic Subtypes.

BACKGROUND AND PURPOSE: Chordoid meningiomas are uncommon WHO grade II primary intracranial neoplasms that possess unique chordoid histology and follow an aggressive clinical course. Our aim was to assess the utility of qualitative MR imaging features and quantitative apparent diffusion coefficient values as distinguishing preoperative MR imaging metrics to identify and differentiate chordoid histology from other meningioma histologic subtypes. MATERIALS AND METHODS: Twenty-one patients with meningiomas with chordoid histology, which included both chordoid meningiomas (>50% chordoid histology) and meningiomas with focal chordoid histology (<50% chordoid histology) with available preoperative MR imaging examinations, including diffusion-weighted imaging, were identified. Qualitative imaging features and quantitative ADC values were compared between meningiomas with chordoid histology and 42 nonchordoid meningiomas (29 WHO grade I, eleven WHO grade II, and 2 WHO grade III). RESULTS: The median ADC (10-3mm2/s) of meningiomas with chordoid histology was significantly higher than nonchordoid meningiomas (1.16 versus 0.92, P < .001), as was the median normalized ADC (1.60 versus 1.19, P < .001). In subgroup analysis, the median and normalized ADC values of chordoid meningiomas (n = 11) were significantly higher than those in meningiomas with focal chordoid histology (n = 10, P < .001 and P < .001, respectively) or nonchordoid meningiomas (n = 42, P < .001 and <0.001, respectively). Median and normalized ADC values were not significantly different between the meningiomas with focal chordoid histology and nonchordoid meningiomas (P = .816 and .301, respectively). Among the qualitative imaging features, only DWI signal intensity was significantly associated with meningiomas with chordoid histology diagnosis. CONCLUSIONS: ADC values are higher in chordoid compared with nonchordoid meningiomas and may be used to discriminate the degree of chordoid histology in meningiomas. While qualitative MR imaging features do not strongly discriminate chordoid from nonchordoid meningiomas, DWI may allow preoperative identification of chordoid meningiomas.

Rabies control in Mexico.

Rabies in dogs was unknown in the Americas before the arrival of the Spanish "Conquistadores". Until the mid-1980s rabies in animals and, in turn in humans, changed little from year to year, with the number of dog vaccinations reported annually rarely reaching one million. In Mexico, the national rabies control programme using mass parenteral vaccination of dogs started in 1990 with about seven million dogs vaccinated the same year. The number of vaccinated dogs exceeded 10 and 15 million in 1995 and 2005, respectively. Modern cell culture-based inactivated rabies virus vaccines were used. A key factor for the success of the dog rabies control program was the supply of potent canine rabies vaccines. Between 1990 and 2005, more than 150 million vaccine doses from 300 lots were administered. Each lot was tested for potency prior to use in the field. The required minimum content of rabies virus antigen for vaccines was 2 IU, in accord with WHO standards. Testing revealed antigen contents ranging from 3.28 to 5.59 IU. As a result of the mass dog vaccination campaigns, human rabies cases due to dog-mediated rabies decreased from 60 in 1990 to 0 in 2000. The number of rabies cases in dogs decreased from 3,049 in 1990 to 70 cases last year.

Microalgal mediation of ripple mobility.

The interaction between physical and biological factors responsible for the cessation of ripple migration on a sandy intertidal flat was examined during a microalgal bloom period in late winter/early spring, as part of a wider study into the biostabilisation of intertidal sediments. Ripple positions and ripple geometry were monitored, and surface sediment was sampled, at weekly intervals over a 5-week period. Ripples remained in the same position for at least 4 weeks, during which time there was a progressive reduction in bedform height (smoothing) and deposition of some 1.5 cm sediment, mainly in the ripple troughs (surface levelling). The mean chlorophyll a (chl a) sediment content was 6.0 microg gDW(-1) (DW: dry weight) (0-1 mm depth fraction), with a maximum value of 7.4 microg gDW(-1) half way through the bloom. Mean colloidal-S carbohydrate (S: saline extraction) content was 131 microg GE gDW(-1) (GE: glucose equivalent) (0-1 mm), with a maximum of 261 microg GE gDW(-1 )towards the end of the bloom. Important accessory pigments were peridinin (indicative of dinophytes) and fucoxanthin (diatoms). Stepwise multiple regression showed that peridinin was the best predictor of chl a. For the first time, in situ evidence for the mediation of (wave) ripple migration by microalgae is provided. Results indicate that diatoms, and quite possibly dinophytes, can have a significant effect on intertidal flat ripple mobility on a temporal scale of weeks. In addition, microalgal effects appear capable of effecting a reduction in bed roughness on a spatial scale of up to 10(-2 )m, with a subsequent reduction in bottom stress and bed erodability. It is suggested that a unique combination of environmental conditions, in conjunction with the microalgal bloom(s), promoted the initial cessation of ripple movement, and that stationary-phase, diatom-derived extracellular polymeric substances (EPS) (and possibly dinophyte-derived EPS) may have prolonged the condition. It is reasonable to suppose that ripple stabilisation by similar processes may have contributed to ripple mark preservation in the geological record. A conceptual model of sandy intertidal flat processes is presented, illustrating two conditions: (i) a low EPS/microalgae sediment content with low ripple stabilisation and preservation potential; and (ii) a high EPS/microalgae content with higher preservation potential.

Halocarbon and dimethyl sulphide studies around the Mascarene Plateau.

Air-sea exchange is thought to be one of the major routes by which halocarbons and dimethyl sulphide reach the troposphere and stratosphere. Once there, in different ways, they participate in chemical reactions that have implications for ozone depletion and climate change. The gases are released by phytoplankton and other algae, but our present understanding of the sources and sinks is insufficient to establish a balanced global budget. Published data suggest that there are regions of coastal and ocean waters that constitute a major source, but, for halocarbons, in other regions the ocean is a net sink. For example, in many open oceanic areas, the rate of degradation of methyl bromide outweighs production. Here we present data from the Central Indian Ocean, a region considered to be low in terms of biological productivity. Little is known about trace-gas release from the Central Indian Ocean and without such data it is impossible to even hazard a guess at the global ocean source to the atmosphere.

[An evaluation of the Mexico-BID Health Services Improvement Program, 1991]. / Evaluación del Programa de Mejoramiento de Servicios de Salud México-BID, 1991.

The evaluation of the program for enhancing health services showed advances in the building and provision of equipment for the health units, as well as development of additional operative capability until 1991. One of the main characteristics of the evaluation process, was the utilization of the local and state information systems, which allow the selective use of indicators in order to identify the advances of the program of expanded coverage and enhance of the quality of care and its direct relationship with the organization of health services. The present research constitutes a good example of the development of programmes funded by multilateral organizations.

[Trends in health services research in Mexico, 1984-1991]. / Tendencias de investigación en servicios de salud en México, 1984-1991.

Health services research is a basic tool for the development of the National Health System. This paper presents the results of a national survey on research projects carried out in Mexican health institutions, as well as in universities and research centers, from 1984 to 1991.

[Epidemiologic overview of measles in Mexico: current situation and perspectives]. / Panorama epidemiológico del sarampión en México: situación actual y perspectivas.

It has been recognized that due to immunization campaigns and specific treatment of medical complications, has resulted in a reduced measles mortality in México as in others countries. However, during the last few years the number of measles cases in México has shown an increasing trend over previous years due to two larges epidemics, in 1985 and 1989. As a vaccine preventable disease, the number of measles cases has shown an important decline in mortality as compared with mortality in the general population. From the total deaths in children under five years the measles deaths have been reduced from a level of 2.8% in 1969 to a level of 1.6% in 1985. The more recent mortality data available shows that 597 deaths caused by measles were registered in 1986, for a mortality rate of 0.75 per 100,000 inhabitants. At higher rate was observed in the age groups less than 1 year with a mortality rate of 5.9 per 100,000 inhabitants compared with 4.2 in the group from 1 to 4 years. The morbidity epidemiologic surveillance system among governmental health services reported a total of 20,076 cases in 1989, with an incidence rate of 23.8 cases per 100,000 inhabitants and a estimated mortality rate of 6.6%. This recent emergence of the measles activity in México is part of a pandemic that is affecting several countries around the world. The impact of these cases on an increased demand of medical care as well as its clinical complications, outcome and mortality, makes measles a high priority problem in México.