Human THP-1 monocyte uptake and cellular disposition of 14C-grepafloxacin.

Uptake of (14)C-grepafloxacin into human mononuclear (THP-1) cells was determined at pH 7.4, 6.8, or 5.0 over a 4-log antibiotic concentration. Grepafloxacin was taken up by THP-1 monocytes rapidly by both a passive and an active transport mechanism at pH 7.4. Its uptake was initially linear, with equilibrium being reached after approximately 1 h. Efflux followed first-order clearance and was complete within 1 h, suggesting no longterm sequestering of the antibiotic occurred. Neither cell number nor serum protein binding appeared to have any effect on antibiotic uptake. High intracellular concentrations were achieved and the ratios of cellular to extracellular antibiotic concentration (IC/EC) were between 529 and 644 at 0.04 micro g/ml at pH 7.4 and 6.8, suggesting that monocytes may contain sufficient levels of grepafloxacin for affecting bacteriostatic killing. Grepafloxacin disposition within the THP-1 monocytes showed large amounts present in the nucleus and cell sap in stimulated and unstimulated cells, and its presence was evenly distributed throughout the cytosol, nuclei, lysosomes, mitochondria, and ribosomes. After stimulation by zymogen A, Staphylococcus aureus, or Streptococcus pneumoniae, increased amounts of grepafloxacin were found within THP-1 monocytes and isolated phagosome vacuoles. No antibiotic sequestration occurred inside stimulated monocytes, although a sufficient intracellular grepafloxacin concentration was available to kill phagocytized bacteria. Metabolic inhibitors, suppressors of K(+)/Cl(-) and Cl(-) transporters, inhibitors of the phagocytic process, low temperature, and low pH inhibited grepafloxacin uptake by THP-1 monocytes.

Newborns killed or left to die by a parent: a population-based study.

CONTEXT: Interest in the discarding or killing of newborns by parents has increased due to wide news coverage and efforts by states to provide Safe Haven legislation to combat the problem. OBJECTIVE: To describe the characteristics of these cases in North Carolina. DESIGN, SETTING, AND POPULATION: Case series derived from data on all deaths among liveborn infants 0 to 4 days of age reported to the North Carolina medical examiner from 1985 through 2000. MAIN OUTCOME MEASURES: Incidence of newborns known to have been killed or discarded by a parent; epidemiological characteristics of newborns and parents. RESULTS: There were 34 newborns known to have been killed or discarded by a parent, comprising 0.002% of all liveborn infants during the 16-year study period, giving a rate of 2.1 per 100 000 per year. A total of 58.8% were male, 41.1% were white, and 52.9% were black. For 29 cases, the perpetrator was determined to be the mother. Among mothers, 50% were single and 20.6% were married (marital status of the remainder was unknown). Thirty-five percent had had other children. Eight mothers (23.5%) were known to have received some prenatal care. The mean age of the mothers was 19.1 years (range, 14-35 years) and more than half were aged 18 years or older. The most common causes of death were asphyxiation/strangulation (41.1%) and drowning (26.5%). CONCLUSIONS: In North Carolina, at least 2.1 per 100 000 newborns are known to be killed or left to die per year, usually by their mothers. It is unknown how many of these deaths might be prevented by Safe Haven laws. Efforts to educate the public about these laws need to target the general public. Where resources are limited, the focus should be on on adolescent pregnancy prevention programs, young adults, prenatal care clinics, and married women.

Female intimate partner homicide: a population-based study.

OBJECTIVES: To identify the patterns of female intimate partner homicide, to describe the nature of the partner relationships between victims and perpetrators, and to determine the extent of intimate partner violence (IPV) preceding the homicide. METHODS: We reviewed North Carolina medical examiner records and conducted telephone interviews with law enforcement officers about partner homicides of women age 15 and older occurring in North Carolina from 1991 to 1993. RESULTS: Most women were killed in homes (80%) and with guns (66%). One hundred thirty-five women (of 293 cases) were killed by marital partners, 47 of them former partners. Nonmarital partners killed 158 women, 46 of them former partners. Intimate partner violence was noted in two-thirds of the cases, 70% of those involving marital partners and 64% involving nonmarital partners. Homicides by former nonmarital partners were the most likely to have been preceded by IPV (78%). One hundred six victims with histories of IPV had had contact with law enforcement or judicial systems in the year before death. CONCLUSIONS: Legal and health care professionals should be aware that women are vulnerable to both IPV and homicide from both nonmarital and former partners as well as from current husbands.

Disposition and intracellular activity of azithromycin in human THP-1 acute monocytes.

Uptake of [14C]-azithromycin into THP-1 human monocytes was determined at pH 7.4, 6.8 or 5.5 over 4-log antibiotic concentrations for 24 h under a number of conditions. Stimulation of cells was with bacteria, latex beads, lipopolysaccharide (LPS), or zymogen A. Subcellular organelle disposition was determined after isolation by ultracentrifugation or sucrose gradients. Hydrolytic enzyme activities and mediators of intracellular inflammation (IL-1, IL-6, IL-8, and TNFalpha) were assessed. Azithromycin uptake into human THP-1 monocytes was initially linear achieving approximately 2% of the extracellular concentration. At pH 7.4, uptake was both passive- and carrier-mediated, but as the pH became more acidic, the uptake was exclusively passive. The intracellular concentration was not pH-dependent over 24 h. Uptake was dependent upon temperature but not the presence of foetal calf serum. Intracellular disposition in zymogen A-stimulated and unstimulated cells was throughout all compartments of the cell, but was higher in the nucleus and cell sap. Phagosomes of stimulated cells contained higher level of the antibiotic. Efflux from THP-1 monocytes was complete between 3 and 4 h. After 1 h treatment with zymogen A, THP-1 monocytes demonstrated an increase in intracellular acidity, protein kinase C, SOD and NAG activities, and NO, H(2)O(2), TNFalpha and IL-1 release over the 1st h. After 2-4 h the pH became alkaline, activities of NADPH reductase, NAG and cathepsin were reduced, and the release of NO, H(2)O(2), TNFalpha and IL-6 were suppressed. Protein synthesis and killing of the bacteria was evident in bacteria kept in monocyte-free medium and those phagocytized by the THP-1 monocytes moderately at 2 h, but more significantly at 24 h. The early killing of the bacteria appears to be a cidal mechanism whereas later, a standard bacteriostatic mechanism was evident. Nevertheless, suppression of these chemical mediators and hydrolytic enzyme activities would reduce the infection and the spread to adjacent areas.

In vitro assessment of urinary isolates of ampicillin-resistant enterococci.

OBJECTIVE: Susceptibility and minimum inhibitory concentration (MIC) studies of ampicillin-resistant enterococci (ARE) were performed with vancomycin, ciprofloxacin, and trovafloxacin. Ampicillin MICs were determined to make comparisons with achievable urinary concentrations of ampicillin. DESIGN: From July 1998 to April 1999, all enterococci isolated from urinary specimens were tested for susceptibility to ampicillin by disk diffusion. For all ARE, vancomycin, ciprofloxacin, and trovafloxacin susceptibilities were determined by use of either disk diffusion or the E-test. Ampicillin MICs were determined for these isolates by liquid agar microdilution testing. ARE were identified to the species level on the basis of biochemical reactions. SETTING: The study was performed at a university-affiliated tertiary care hospital. OUTCOME MEASURES: In vitro susceptibility studies and MIC determinations were performed in accordance with the National Committee for Clinical Laboratory Standards. RESULTS: A total of 310 urine samples were culture positive for enterococcus. Thirty (9.7%) unduplicated isolates were resistant to ampicillin. Of these, nine ARE isolates (30%) were also vancomycin resistant, whereas only 2 ampicillin-susceptible isolates were vancomycin resistant (p < 0.05). All ARE were resistant to ciprofloxacin, and 29 (96.7%) were resistant to trovafloxacin. Nine (30%), 18 (60%), and 3 (10%) isolates had an ampicillin MIC of 128, 256, and 512 micrograms/mL, respectively. Ampicillin MICs did not differ significantly between vancomycin-susceptible and -resistant isolates (p = 0.963). Twenty-seven isolates (90%) were identified as Enterococcus faecium; the other 3 were either Enterococcus avium or Enterococcus raffinosus. CONCLUSIONS: Ampicillin resistance is associated with resistance to vancomycin. Most ARE are resistant to fluoroquinolone antibiotics such as ciprofloxacin and trovafloxacin. Ampicillin MICs for ARE found in these urinary specimens were all within 1 dilution of 256 micrograms/mL, a concentration achievable in the urine with higher doses of oral amoxicillin or intravenous ampicillin. Additional studies are needed to assess the clinical implications of these data.

Effectiveness of safety measures recommended for prevention of workplace homicide.

CONTEXT: Homicide is the second leading cause of death on the job for US workers. Government agencies recommend that employers prevent violence against workers by adopting interventions originally designed to prevent robbery, but the effectiveness of these interventions is unknown. OBJECTIVE: To investigate the effectiveness of existing administrative and environmental interventions recommended for preventing workplace homicide. DESIGN, SETTING, AND PARTICIPANTS: Population-based case-control study of North Carolina workplaces where a worker had been killed between January 1, 1994, and March 31, 1998, identified through a statewide medical examiner system (cases; n = 105) and an industry-matched random sample of workplaces at risk during the same period, selected from business telephone listings (controls; n = 210). MAIN OUTCOME MEASURE: Risk of death of a worker due to homicide. RESULTS: Among environmental interventions, strong and consistent reductions in the risk of a worker being killed on the job were associated with bright exterior lighting (odds ratio [OR], 0.5; 95% confidence interval [CI], 0.3-1.0). Among administrative interventions, the largest beneficial effect was for staffing practices that prevented workers from being alone at night (OR, 0.4; 95% CI, 0.2-0.9). Keeping doors closed during working hours was also associated consistently with substantially reduced risk (OR, 0.4; 95% CI, 0.1-1.1) but was not statistically significant. Combinations of 5 or more administrative measures were associated with significantly lower levels of risk (OR, 0.1; 95% CI, 0.0-0.5). CONCLUSIONS: We found evidence suggesting that eliminating solo work at night could reduce the risk of homicide for workers. Keeping doors closed and using bright exterior lighting or combinations of administrative interventions also appear to be beneficial, but there was no evidence of effectiveness for a number of other recommended measures.