Biomedical subjects

C Loftin

Publications and source records attributed to C Loftin.

11 recordsLinked to original sources

PubMed2001

The COX-2 inhibitor NS-398 causes T-cell developmental disruptions independent of COX-2 enzyme inhibition.

Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit the function of cyclooxygenases, COX-1 and COX-2, which catalyze the first step in the synthesis of inflammatory mediators (PGE2). We sought to understand the roles of cyclooxygenases and NSAIDs in T-cell development. Our data show no significant defects in T-cell development in fetal thymic organ cultures of mice disrupted in both or either COX genes or in mice disrupted in either EP-1 or EP-2 receptor genes. On the other hand, NSAIDs reproducibly caused thymocyte developmental defects. However, the specific effects of the COX-2 inhibitors were not correlated with their potency for inhibition of COX-2 activity. We focused on the NS-398 COX-2 inhibitor and showed that its effects could not be reversed by exogenous PGE2. Furthermore, NS-398 was inhibitory even when its target, COX-2, was absent. These data show that the T-cell developmental effects of NS-398 are COX-2 and PGE2 independent.

Animals↗

PubMed1999

Cyclooxygenase knockout mice: models for elucidating isoform-specific functions.

The development of cyclooxygenase (COX) deficient mice has allowed investigation into the individual physiological roles of the COX-1 and COX-2 isoforms. In the following article, the phenotypes of the two Ptgs (genes coding for COX-1 and COX-2) knockouts are summarized, and recent studies to investigate the effects of COX deficiency on cancer susceptibility, inflammatory response, gastric ulceration, and female reproductive processes are discussed. Also, the development and potential uses of mice deficient in both COX isoforms and mice containing only a single copy of one isoform are discussed. Additionally, when the data permit, the effects of genetic ablation of COX activity are compared with those of pharmacological inhibition of COX activity by nonsteroidal anti-inflammatory drugs. The data suggest that prostaglandins derived via the individual COX isoforms have separate as well as common functions. However, for the maintenance of normal physiology, it appears that deficiency of COX-2 has more profound effects than deficiency of COX-1.

Animals↗

PubMed1998

Fatal firearm-related injury surveillance in Maryland.

CONTEXT: Maryland began a statewide firearm-related injury surveillance system in 1995. The system now focuses on firearm-related deaths; a system to monitor nonfatal injuries is being developed. The system is passive; it accesses, integrates, and analyzes data collected by Maryland's Office of the Chief Medical Examiner, Maryland State Police, and Division of Health Statistics. OBJECTIVE: To evaluate the surveillance system's ability to ascertain cases in the absence of a standard for the true number of cases. DESIGN: Link records of the same firearm-related death captured by the surveillance system's multiple data sources, comparing the rate of false positives and false negatives, and assessing errors in linkage variables. SETTING: Maryland, 1991-1994. PARTICIPANTS: All deaths occurring in the state of Maryland as a result of a firearm-related injury. MAIN OUTCOME MEASURES: Sensitivity and positive predictive value. RESULTS: The system is extremely sensitive, detecting 99.61% of cases, and it has a very high positive predictive value, with 99.87% of the cases identified from medical examiner's office data being confirmed as actual cases. CONCLUSIONS: Maryland's database of information from the medical examiner's office is highly accurate for ascertaining firearm-related deaths that occur in the state. A unique identifier common across data sources would ease record linkage efforts, and improve the system's ability to monitor firearm-related deaths.

Adolescent↗

PubMed1991

Effects of restrictive licensing of handguns on homicide and suicide in the District of Columbia.

BACKGROUND: Whether restricting access to handguns will reduce firearm-related homicides and suicides is currently a matter of intense debate. In 1976 the District of Columbia adopted a law that banned the purchase, sale, transfer, or possession of handguns by civilians. We evaluated the effect of implementing this law on the frequency of homicides and suicides. METHODS: Homicides and suicides committed from 1968 through 1987 were classified according to place of occurrence (within the District of Columbia or in adjacent metropolitan areas where the law did not apply), cause (homicide or suicide), mechanism of death (firearms or other means), and time of occurrence (before or after the implementation of the law). The number of suicides and homicides was calculated for each month during the study period, and differences between the mean monthly totals before and after the law went into effect were estimated. RESULTS: In Washington, D.C., the adoption of the gun-licensing law coincided with an abrupt decline in homicides by firearms (a reduction of 3.3 per month, or 25 percent) and suicides by firearms (reduction, 0.6 per month, or 23 percent). No similar reductions were observed in the number of homicides or suicides committed by other means, nor were there similar reductions in the adjacent metropolitan areas in Maryland and Virginia. There were also no increases in homicides or suicides by other methods, as would be expected if equally lethal means were substituted for handguns. CONCLUSIONS: Restrictive licensing of handguns was associated with a prompt decline in homicides and suicides by firearms in the District of Columbia. No such decline was observed for homicides or suicides in which guns were not used, and no decline was seen in adjacent metropolitan areas where restrictive licensing did not apply. Our data suggest that restrictions on access to guns in the District of Columbia prevented an average of 47 deaths each year after the law was implemented.

Cause of Death↗

PubMed1991

Preventing homicide: an evaluation of the efficacy of a Detroit gun ordinance.

BACKGROUND: In November 1986, a Detroit, Michigan city ordinance requiring mandatory jail sentences for illegally carrying a firearm in public was passed to preserve "the public peace, health, safety, and welfare of the people." METHODS: We conducted a set of interrupted time-series analyses to evaluate the impact of the law on the incidence of homicides, hypothesizing that the ordinance, by its nature, would affect only firearm homicides and homicides committed outside (e.g., on the street). RESULTS: The incidence of homicide in general increased after the law was passed, but the increases in non-firearm homicides and homicides committed inside (e.g., in a home) were either statistically significant or approached statistical significance (p = .006 and p = .070, respectively), whereas changes in the incidence of firearm homicides and homicides committed outside were not statistically significant (p = .238 and p = .418, respectively). We also determined that the ordinance was essentially unenforced, apparently because of a critical shortage of jail space. CONCLUSIONS: Our findings are consistent with a model in which the ordinance had a dampening effect on firearm homicides occurring in public in Detroit. The apparent preventive effect evident in the time series analyses may have been due to publicity about the ordinance, whereas the small nature of the effect may have been due to the lack of enforcement.

Firearms↗

PubMed1986

The validity of robbery-murder classifications in Baltimore.

The most widely used source of nationwide data on homicide in the United States is the Supplementary Homicide Report (SHR) data compiled by the FBI as part of its Uniform Crime Reporting System. This paper describes a study of the reliability of robbery-murder classifications by the SHR for Baltimore, Maryland during 1983. The research is exploratory, but indicates a high level of inconsistency in the data. Of the 42 cases that were classified as robbery murders by the SHR or the replication study, only 20 were classified that way in both studies. The high level of unreliability can be attributed to three major problems: (1) the SHR codes are mutually exclusive, but many homicides could be placed in several of the categories; (2) there are few systematic rules for classifying ambiguously motivated homicides; and (3) the SHR placed too many cases in the "unknown" category. It appears that the reliability of the coding could be increased substantially with relatively minor changes in the procedures currently used.

Baltimore↗

PubMed1986