PubMed Health⌕ Search

Biomedical subjects

A P Martinez

Publications and source records attributed to A P Martinez.

At least 19 recordsLinked to original sources
PubMed2001

Evaluation of human exposure to ambient PM10 in the metropolitan area of Mexico City using a GIS-based methodology.

The main goal of this study was to evaluate the magnitude of outdoor exposure to fine particulate matter (PM10) potentially experienced by the population of metropolitan Mexico City. With the use of a geographic information system (GIS), spatially resolved PM10 distributions were generated and linked to the local population. The PM10 concentration exceeded the 24-hr air quality standard of 150 microg/m3 on 16% of the days, and the annual air quality standard of 50 microg/m3 was exceeded by almost twice its value in some places. The basic methodology described in this paper integrates spatial demographic and air quality databases, allowing the evaluation of various air pollution reduction scenarios. Achieving the annual air quality standard would represent a reduction in the annual arithmetic average concentration of 14 microg/m3 for the typical inhabitant. Human exposure to particulate matter (PM) has been associated with mortality and morbidity in Mexico City; reducing the concentration levels of this pollutant would represent a reduction in mortality and morbidity and the associated cost of such impacts. This methodology is critical to assessing the potential benefits of the current initiative to improve air quality implemented by the Environmental Metropolitan Commission of Mexico City.

Air Pollutants↗
PubMed1992

Second-generation 1,2,4-benzotriazine 1,4-di-N-oxide bioreductive anti-tumor agents: pharmacology and activity in vitro and in vivo.

SR 4233 (1,2,4-benzotriazine-3-amine 1,4-dioxide) will soon be entering Phase I clinical trials as a new bioreductive cytotoxic agent for the treatment of solid tumors in combination with fractionated radiotherapy. We have selected 3 from over 50 analogues of SR 4233 which showed particular promise as second generation bioreductive antitumor agents. These compounds, when compared to SR 4233, have higher hypoxic toxicity and comparable or higher oxic to hypoxic cytotoxicity ratios in vitro and similar animal toxicity. We have compared the effectiveness of these three compounds with SR 4233 in two tumor systems and have examined some pharmacokinetic properties. The results show that replacement of the amino group at the 3-position of SR 4233 with either a hydrogen or an N,N-dialkylaminoalkylamino group shortens the half-life of these compounds in the blood because of the combined effects of partition coefficients, basicity, and higher reactivity. SR 4754 and SR 4755, the N,N-dialkylaminoalkylamino derivatives, exhibited shorter plasma half-lives than SR 4233 but exhibited lower anti-tumor activity than SR 4233 based on equal mouse toxicity in a fractionated regimen. SR 4482, with the hydrogen substitution and very high electron affinity, possessed a very short blood half life yet retained similar anti-tumor activity as SR 4233.

Animals↗
PubMed1992

Trends in suicide (1983-1987).

From over 20,000 autopsies performed by the Department of Forensic Medicine of The London Hospital Medical College over a period of 5 years from 1983 to 1987, 7.4 per cent were classified as unnatural deaths, and from these 659 (3.2 per cent) were suicides. The object of this paper is to study the different methods of self-destruction, the incidence of these methods by sex and age, and evidence left by the deceased.

Adolescent↗
PubMed1987

Factor VIII-associated antigen in human lymphatic endothelium.

Lymphatic vascular endothelium both on tissue section and in culture exhibits positivity for Factor VIII-associated antigen although staining is generally less intense and more spotty than in comparable blood vascular endothelium. Lymphatic endothelium also exhibits Weibel-Palade bodies. Neither marker, therefore, reliably distinguishes blood vascular endothelium from lymphatic endothelium.

Antigens↗
PubMed1986

A technical modification to improve experimental production of hepatogenic ascites.

Constriction of the thoracic inferior vena cava is a useful experimental maneuver to reproduce massive ascites. Unfortunately, the margin of safety of this technique is narrow in that too much constriction overly restricts venous return with subsequent shock and death, and lesser constriction is often associated with extensive venous collateralization via the azygos system and failure to sustain hepatic congestion. By combining azygos vein ligation with 50% constriction of the supradiaphragmatic inferior vena caval circumference at the time of the initial thoracotomy, we have found that intense hepatic congestion is sustained and that dogs consistently develop massive ascites within 2-3 weeks.

Animals↗
PubMed1977

Potential antitumor agents. Some sulfur-substituted derivatives of alpha- and beta-2'-deoxythioguanosine.

A series of ten S-substituted derivatives of the alpha and beta anomers (1a and 1b) of 2'-deoxy-6-thioguanosine has been prepared by S-alkylation of the parent nucleosides and/or by mercaptide displacement reactions on 6-chloro intermediates. Against L1210 murine leukemia all beta anomers were active but potency was reduced relative to 1b. Most S-alkyl alpha anomers were inactive in this test. Limited testing against P388 murine leukemia showed all alpha-anomer derivatives to be inactive but the beta anomers were more effective than the parent. S-Substitution sharply reduced acute toxicity in both series. In vitro DNA and RNA synthesis inhibition data are also reported. The antitumor activity of these derivatives and of the 2',5'-di-O-acetyl derivatives of 1a and 1b against lymphoid leukemia L1210 is reported. Some results with the lymphocytic leukemia P388 and an in vitro assay of the inhibition of nucleic acid synthesis are also given.

Animals↗