Adolescents and children injured or killed in drive-by shootings in Los Angeles

BACKGROUND: Drive-by shootings by violent street gangs contribute to early morbidity and mortality among adolescents and children in Los Angeles. This study attempted to determine the frequency of this problem and the population at greatest risk. We also studied the most frequently injured areas of the body, the seasons in which the most shootings occurred, the most common sites for drive-by shootings, and the types of firearms used. METHODS: We retrospectively reviewed the files of the Gang Information Section of the Los Angeles Police Department to identify all drive-by shootings in Los Angeles in 1991 in which a child or adolescent under the age of 18 was shot at, injured, or killed. RESULTS: A total of 677 adolescents and children were shot at, among whom 429 (63 percent) had gunshot wounds and 36 (5.3 percent) died from their injuries. Three hundred three of those with gunshot wounds (71 percent) were gang members. Arms and legs were the areas of the body most commonly injured. Handguns were the most frequently used type of firearm. All the homicide victims were African American or Hispanic, and 97 percent were boys. African American and Hispanic children and adolescents, especially male gang members, had a significantly higher risk than their Asian and white counterparts of injury and death from drive-by shootings in Los Angeles (P < 0.001). CONCLUSIONS: Drive-by shootings involving adolescents and children are frequent in Los Angeles. Although Los Angeles may be an atypical case, understanding why violent street gangs form, preventing causes of violence, and limiting access to firearms are essential steps in preventing this serious problem.     

Continuous planar phospholipid bilayer supported on porous silicon thin film reflector

Reconstituting artificial membranes for in vitro studies of cell barrier mechanisms and properties is of major interest in biology. Here, artificial membranes supported on porous silicon photonic crystal reflectors are prepared and investigated. The materials are of interest for label-free probing of supported membrane events such as protein binding, molecular recognition, and transport. The porous silicon substrates are prepared as multilayered films consisting of a periodically varying porosity, with pore dimensions of a few nanometers in size. Planar phospholipid bilayers are deposited on the topmost surface of the oxidized hydrophilic mesoporous silicon films. Atomic force microscopy provides evidence of continuous bilayer deposition at the surface, and optical measurements indicate that the lipids do not significantly infiltrate the porous region. The presence of the supported bilayer does not obstruct the optical spectrum from the porous silicon layer, suggesting that the composite structures can act as effective optical biosensors.     

Comparative repeatability of guide-pin axis positioning in computer-assisted and manual femoral head resurfacing arthroplasty

The orientation of the femoral component in hip resurfacing arthroplasty affects the likelihood of loosening and fracture. Computer-assisted surgery has been shown to improve significantly the surgeon's ability to achieve a desired position and orientation; nevertheless, both bias and variability in positioning remain and can potentially be improved. The authors recently developed a computer-assisted surgical (CAS) technique to guide the placement of the pin used in femoral head resurfacing arthroplasty and showed that it produced significantly less variation than a typical manual technique in varus/valgus placement relative to a preoperatively determined surgical plan while taking a comparable amount of time. In the present study, the repeatability of both the CAS and manual techniques is evaluated in order to estimate the relative contributions to overall variability of surgical technique (CAS versus manual), surgeon experience (novice versus experienced), and other sources of variability (e.g. across specimens and across surgeons). This will enable further improvements in the accuracy of CAS techniques. Three residents/fellows new to femoral head resurfacing and three experienced hip arthroplasty surgeons performed 20-30 repetitions of each of the CAS and manual techniques on at least one of four cadaveric femur specimens. The CAS system had markedly better repeatability (1.2 degrees) in varus/valgus placement relative to the manual technique (2.8 degrees), slightly worse repeatability in version (4.4 degrees versus 3.2 degrees), markedly better repeatability in mid-neck placement (0.7 mm versus 2.5 mm), no significant dependence on surgeon skill level (in contrast to the manual technique), and took significantly less time (50 s versus 123 s). Proposed improvements to the version measurement process showed potential for reducing the standard deviation by almost two thirds. This study supports the use of CAS for femoral head resurfacing as it is quicker than the manual technique, independent of surgeon experience, and demonstrates improved repeatability.     

Depressive symptoms among amphetamine and cocaine users before and after substance abuse treatment.

This study examined whether higher rates of depressive symptoms among amphetamine compared with cocaine users result from amphetamine use itself, polydrug use, or experiencing a major lifetime depressive episode and whether depressive symptoms among amphetamine users are more likely to persist 12 months after treatment. The association between amphetamine use and depressive symptoms disappears when controlling for polydrug use and lifetime major depressive episode. Polydrug use and lifetime depressive episode are significantly related to depressive symptoms in the year preceding treatment. Amphetamine use at intake does not predict depressive symptoms among individuals who are abstinent at follow-up, and amphetamine users are no more likely than cocaine users to report depression at a 12-month follow-up. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The epidemic of gang-related homicides in Los Angeles County from 1979 through 1994

OBJECTIVE: To determine trends in gang homicides and the population at greatest risk for homicide by reviewing all gang-related homicides in Los Angeles County, California, from January 1979 to December 1994. DESIGN: Homicide files of the Los Angeles Police Department and the Los Angeles County Sheriff's Department from 1979 to 1994 involving violent street gang activity were reviewed. Gang files were reviewed for demographic data, weapons used, homicides by drive-by shootings, and times and geographic areas of occurrence. SETTING: Los Angeles County from January 1, 1979, to December 31, 1994. MAIN OUTCOME MEASURES: Age, race, and sex of gang-related homicide victims; frequency of weapon use; and the change in gang-related homicide rates during the study period. RESULTS: A total of 7288 gang-related homicides occurred in Los Angeles County from 1979 through 1994; 5541 of these homicides occurred in Los Angeles Police Department and Los Angeles County Sheriff's Department jurisdictions. During the study period, the proportion of all homicides that were gang related increased from 18.1% to 43.0% (P < .001). Of the 5541 gang-related homicide victims, 4580 (85.6%) were aged 15 to 34 years, 93.3% were African American or Hispanic, 5157 (93.2%) were male, 3559 (64.2%) were gang members, and 1408 (25.4%) occurred during drive-by shootings. Firearms were used in an increasing proportion of homicides, from 71.4% in 1979 to 94.5% in 1994. Homicides by semiautomatic handguns dramatically increased during the study period. Gang-related homicide rates for African-American males aged 15 to 19 years increased from 60.50 per 100,000 population per year in 1979 to 1981 to 192.41 per 100,000 population per year in 1989 to 1991. CONCLUSIONS: Gang-related homicides in Los Angeles County have reached epidemic proportions and are a major public health problem. To prevent gang violence, the root causes of violent street gang formation must be alleviated, the cycle of violent street gang involvement must be broken, and access to firearms must be limited.     

Antibody-induced antigen redistribution and shedding from human breast cancer cells

Cell surface antigens of human breast cancer cells undergo a rapid redistribution when bound by antibodies from cancer patients. The subsequent shedding of these antigen-antibody complexes and free antigen may be instrumental in tumor survival.     

Children's acquisition of the English cardinal number words: A special case of vocabulary development.

When children produce the names of the cardinal numbers from 1 to 1,000,000,000,000 in English, it is unlikely that they have previously learned all of these words. Rather, children have probably learned small set of basic number words and by combining these elements, construct additional words. To understand the development of number-word construction, students in Grades 1, 3, 5, and 7 named and counted from a set of numbers into the billions in 2 studies. Times taken to produce numbers were also recorded in Study 2. Despite large individual differences within grade, number knowledge increase dramatically with age, and many students in Grades 1, 3, 5, and 7 produced number words in the hundreds, thousands, millions, and billions, respectively. In Study 2, times to name and count decrease substantially with grade. The findings are discussed both in relation to children's growing knowledge to the number system and to vocabulary development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)