Evaluation of Combination Drug Therapy for Treatment of Antibiotic-Resistant Inhalation Anthrax in a Murine Model.

Bacillus anthracis is considered a likely agent to be used as a bioweapon, and the use of a strain resistant to the first-line antimicrobial treatments is a concern. We determined treatment efficacies against a ciprofloxacin-resistant strain of B. anthracis (Cipr Ames) in a murine inhalational anthrax model. Ten groups of 46 BALB/c mice were exposed by inhalation to 7 to 35 times the 50% lethal dose (LD50) of B. anthracis Cipr Ames spores. Commencing at 36 h postexposure, groups were administered intraperitoneal doses of sterile water for injections (SWI) and ciprofloxacin alone (control groups), or ciprofloxacin combined with two antimicrobials, including meropenem-linezolid, meropenem-clindamycin, meropenem-rifampin, meropenem-doxycycline, penicillin-linezolid, penicillin-doxycycline, rifampin-linezolid, and rifampin-clindamycin, at appropriate dosing intervals (6 or 12 h) for the respective antibiotics. Ten mice per group were treated for 14 days and observed until day 28. The remaining animals were euthanized every 6 to 12 h, and blood, lungs, and spleens were collected for lethal factor (LF) and/or bacterial load determinations. All combination groups showed significant survival over the SWI and ciprofloxacin controls: meropenem-linezolid (P = 0.004), meropenem-clindamycin (P = 0.005), meropenem-rifampin (P = 0.012), meropenem-doxycycline (P = 0.032), penicillin-doxycycline (P = 0.012), penicillin-linezolid (P = 0.026), rifampin-linezolid (P = 0.001), and rifampin-clindamycin (P = 0.032). In controls, blood, lung, and spleen bacterial counts increased to terminal endpoints. In combination treatment groups, blood and spleen bacterial counts showed low/no colonies after 24-h treatments. The LF fell below the detection limits for all combination groups yet remained elevated in control groups. Combinations with linezolid had the greatest inhibitory effect on mean LF levels.

Influenza A virus and TLR7 activation potentiate NOX2 oxidase-dependent ROS production in macrophages.

Influenza A virus infects resident alveolar macrophages in the respiratory tract resulting in Toll like receptor 7 (TLR7) activation that triggers an inflammatory response to resolve the infection. Macrophages are also major sources of reactive oxygen species (ROS) via the NOX2-containing NADPH oxidase. Although ROS are crucial for pathogen clearance, in response to influenza A virus, ROS are touted as being culprit mediators of the lung tissue injury. The aim of the present study was to determine whether influenza A virus infection and TLR7 activation of macrophages, results in alterations in their ROS production. Here we demonstrate using immunofluorescence that influenza A virus (Hong Kong X-31 strain; H3N2) internalizes in RAW264.7 cells and mouse alveolar macrophages within 1 h, resulting in a significant enhancement in the stimulated NOX2 oxidase-dependent oxidative burst, although virus had no effect on basal ROS. The specific TLR7 agonist imiquimod (10 µg/ml) elevated basal superoxide production and, in a similar fashion to influenza A virus, enhanced NOX2 oxidase-dependent oxidative burst. By contrast, the TLR3 agonist, poly I:C (1-100 µg/ml) failed to influence the oxidative burst to NOX2 oxidase. A peptide corresponding to the region 337-348 on p47phox conjugated to a HIV-tat, designed to inhibit the phosphorylation of Ser346 on p47phox suppressed the influenza A virus- and imiquimod-induced enhancement in the oxidative burst. In conclusion, this study demonstrates for the first time that influenza A virus and TLR7 activation enhance the NOX2 oxidase-dependent oxidative burst in macrophages, which might underpin the acute lung injury to influenza A virus infection.

Nutritional status of HIV-infected women with tuberculosis in Dar es Salaam, Tanzania.

SETTING: Tuberculosis (TB) treatment clinics in Dar es Salaam, Tanzania. OBJECTIVE: To quantify anthropometrics and intake of en-ergy and protein among human immunodeficiency virus (HIV) positive women with TB. DESIGN: HIV-positive women with newly diagnosed TB were assessed on their anthropometric characteristics and dietary intake. Energy and protein intake were determined using Tanzania food composition tables and compared with standard recommendations. Patients were re-evaluated after 4-6 months of anti-tuberculosis treatment. RESULTS: Among 43 women, the baseline median CD4 count was 209 cells/µl (range 8-721); 19 (44%) had a CD4 count of <200; 20 (47%) were on antiretroviral therapy. Body mass index was <18.5 kg/m(2) in 25 (58%); the median food insecurity score was 6. The median level of kcal/day was 1693 (range 1290-2633) compared to an estimated need of 2658; the median deficit was 875 kcal (range -65-1278). The median level of protein/day was 42 g (range 27-67) compared to 77 g estimated need; the median protein deficit was 35 g (range 10-50). The median weight gain among 29 patients after 4-6 months was 6 kg. CONCLUSION: HIV-positive women with TB have substantial 24-h deficits in energy and protein intake, report significant food insecurity and gain minimal weight on anti-tuberculosis treatment. Enhanced dietary education together with daily supplementation of 1000 kcal with 40 g protein may be required.

Injury surveillance for youth on farms in the U.S., 2006.

In order to provide injury surveillance for youth on farms in the U.S., the National Institute for Occupational Safety and Health (NIOSH), in partnership with the USDA, developed the Childhood Agricultural Injury Survey (CAIS). CAIS data for all youth less than 20 years of age on farms have been collected for the calendar years of 1998, 2001, 2004, and 2006. CAIS data from 2006 indicated that an estimated 30.7 million youth lived on, worked on, or visited U.S. farms. These youth experienced almost 23,000 injuries while on the farm. The majority of these injuries occurred to males (15,223) and youth between the ages of 10 and 15 years (10,158). Approximately 25% (5,773) of the injuries were related to work being done on the farm. Youth living on the farm incurred 51% (11,654) of the injuries, hired youth sustained 6% (1,363), and 40% were to visiting youth (9,729). Although youth injuries on farms have declined by 30% since 1998, the numbers are still unacceptably high. Further indepth evaluation of subsets of the youth population may serve to better direct safety intervention programs and research.

Consequences for the bovine embryo of being derived from a spermatozoon subjected to oxidative stress.

OBJECTIVE: To determine whether oxidative damage of ejaculated frozen-thawed sperm prior to oocyte insemination in vitro affects the competence of the resultant embryo to develop to the blastocyst stage. METHOD: Extended frozen semen from bulls was thawed, subjected to Percoll gradient purification to obtain motile spermatozoa and mixed with medium containing the pro-oxidants menadione or tert-butyl hydroperoxide. After 3 h at 38.5 degrees C, the sperm were washed and used to inseminate oocytes in vitro. Embryo development proceeded until 8 days after insemination. RESULTS: Treatment of sperm with 15 or 30 micromol/L menadione reduced the proportions of oocytes that cleaved and those that developed to the blastocyst stage; 30 micromol/L menadione reduced the proportion of cleaved embryos that developed to the blastocyst stage at day 8 after insemination. Oocytes inseminated with sperm treated with 150 or 300 micromol/L tert-butyl hydroperoxide had lower proportions of cleavage and blastocyst development, and the proportion of cleaved embryos becoming blastocysts was also reduced. CONCLUSION: Oxidative damage to ejaculated sperm can compromise the ability of the sperm to cause oocyte cleavage and leads to formation of embryos with reduced competence for development.

Effects of airport screening X-irradiation on bovine sperm chromatin integrity and embryo development.

Biological samples, including cryopreserved sperm, are routinely X-rayed during air shipment. The goal was to investigate the impact of X-irradiation used for checked and carry-on luggage on bovine sperm chromatin integrity and postfertilization in vitro embryonic development. Frozen domestic bull sperm (Bos taurus) (n=9 bulls) stored in a dry shipper (-160 degrees C) was screened by X-irradiation 0, 1, 2, and 3 times as either carry-on or checked luggage. Duplicate straws were thawed, and sperm were assessed for chromatin damage using the sperm chromatin structure assay (SCSA) and by postfertilization in vitro developmental competence of mature oocytes. Multiple exposure to X-rays did not significantly affect sperm chromatin integrity assessed by SCSA. There were lower proportions of oocytes cleaved (P=0.07; 21.6+/-3.1% vs. 29.4+/-3.1%, 24.9+/-3.1%, and 25.7+/-3.3% for 3 vs. 0, 1, and 2 times, respectively; least-squares means+/-SEM) and that developed to blastocysts (P=0.06; 9.0+/-1.7% vs. 13.8+/-1.7%, 11.5+/-1.7%, and 12.6+/-1.9%, respectively) when fertilization was performed with sperm X-rayed 3 times using checked luggage irradiation; developmental competence (percentage cleaved embryos becoming blastocysts) was unaffected. There were no deleterious effects of other X-irradiation treatments on embryo development. We inferred that screening by X-irradiation may reduce the ability of sperm to activate oocyte cleavage after multiple exposures at the checked luggage dose. However, there was no evidence that competence of embryos to become blastocysts was reduced by X-irradiation (45.4+/-5.7%, 40.4+/-5.7%, 46.4+/-6.1%, and 41.8+/-5.7% for 0, 1, 2, and 3 doses, respectively), but potential long-term epigenetic effects are unknown.

Youth living on Hispanic-operated farms: injuries and population estimates in the U.S., 2000.

A dearth of information exists in public health surveillance on the injury burden among Hispanic farm youth in the U.S. In this study, data were collected via a telephone survey with Hispanic farm operators sampled from the 1991 Census of Agriculture active list of farms. There were an estimated 307 nonfatal injuries among an estimated 21,631 youth less than 20 years old living on Hispanic-operated farms in the U.S., 2000. Males accounted for 73% of the injuries and had an injury rate of 20.2 compared to 8.2 per 1,000 for females. Injury rates were higher for work-related incidents than for nonwork, and this relationship was true for both males and females. Work and nonwork injury rates were also similar for youth < 10 and 10-15 years old, but for youth 16-19 years of age, the risk of injury for work-related incidents was higher than for nonwork. Livestock operations had a larger number of injuries and higher injury rates compared to crop operations. These data provide previously unavailable descriptive statistics for both the nonfatal injury burden and population estimate for youth on Hispanic-operated farms.

Nonfatal injuries to household youth on racial minority-operated farms in the U.S., 2000.

The National Institute for Occupational Safety and Health (NIOSH) estimated that 32,808 nonfatal injuries occurred to youth less than 20 years of age on U.S. farms during 1998. These data, however, do not allow for the identification of minority farm operators. The Minority Farm Operator Childhood Agricultural Injury Survey (M-CAIS) was conducted to provide an overview of the number of youth on minority-operated farms and their associated farm-related injuries during 2000. M-CAIS was conducted by the USDA for NIOSH through a telephone survey of 49,270 minority-operated farms identified in the 1997 Census of Agriculture. These minority-operated farms included four racial categories (black, Asian, Native American, and other) and operators of Hispanic ethnicity. This study included only racial minority-operated farms for analysis, white Hispanic farms were excluded. In 2000, there were an estimated 28,577 youth living on U.S. farms operated by racial minorities. In that year, these youth sustained an estimated 348 nonfatal injuries. Males accounted for 245 (70%) of the injuries to household youth. The majority of all injuries to household youth (247, 71%) occurred on livestock operations. Native American household youth accounted for both the largest number of injuries (177) and the highest rate of injury (24.0/1,000 household youth) on these farms. M-CAIS data indicated significant variation in injury rates among specific racial categories. Results of the M-CAIS suggest the need for prevention strategies to address issues found within these specific sub-populations of the agricultural community.

Effect of repeated administration of PGF2alpha in the early post partum period on the prevalence of clinical endometritis and probability of pregnancy at first insemination in lactating dairy cows.

Two experiments were performed to determine the effects of repeated administration of PGF2alpha in the immediate post partum period on the prevalence of clinical endometritis at 22 and 58 days post partum, and the probability of pregnancy at first insemination, in post partum dairy cows. In Experiment 1, 228 cows on day 7 post partum were used. Cows in Group 1 (n = 114) were treated twice with PGF2alpha (25 mg, im) 8 h apart on days 7 and 14 post partum, and only once on days 22 and 35 post partum. Cows in Group 2 (n = 114) served as untreated controls. Vaginoscopy and transrectal palpation of the genital tract were done on days 22 and 58 post partum. Cows in both groups were inseminated at estrus after a voluntary waiting period of 100 days. Pregnancy was determined by transrectal palpation between 45 and 50 days after insemination. Repeated administration of PGF2alpha in the immediate post partum period did not reduce the prevalence of clinical endometritis on days 22 or 58 post partum (65 versus 62% on day 22 and 28.3 versus 35.2% on day 58 in Groups 1 and 2, respectively). There was no significant difference in the probability of pregnancy at first insemination between cows in both groups. In Experiment 2, 418 cows on day 7 post partum were used. Cows in Group 1 (n = 209) were treated twice with PGF2alpha (25 mg, im) 8h apart on days 7 and 14 post partum, and only once on days 22 and 35 post partum. Cows in Group 2 (n = 209) served as untreated controls. Cows in both groups were subjected to the Presynch and Ovsynch protocols on days 49 and 75 post partum, respectively. Pregnancy was determined by transrectal ultrasonography between days 29 and 32 after timed insemination. There was no significant difference in the probability of pregnancy at first insemination between cows in both groups. In conclusion, repeated administration of PGF2alpha to cows in this herd had no effect on the prevalence of clinical endometritis at 22 and 58 days post partum, and that there was no effect on the probability of pregnancy after insemination at estrus among cows with a voluntary waiting period of > 100 days, or at timed AI at 85 days in milk when Presynch was employed.

Ceramic-on-ceramic versus ceramic-on-polyethylene bearings in total hip arthroplasty: Results of a multicenter prospective randomized study and update of modern ceramic total hip trials in the United States.

One reason why otherwise well-functioning total hip replacements have a finite service life is eventual aseptic loosening of the implants because of osteolysis induced by wear particles from the artificial bearing. Pain and osteolysis from wear debris can manifest even in the absence of aseptic loosening. Total hip replacements with ceramic-on-ceramic articulations have shown less wear both in vitro and in vivo. A randomized prospective clinical trial was conducted to compare the outcomes of ceramic-on-ceramic articulations to ceramic-on-polyethylene articulations. Two-year data are of interest because premature failures of ceramic femoral heads usually occur by this time interval. Of 500 patients enrolled in this trial, half received total hip replacements with alumina-on-alumina bearings, while the other half had ceramic-on-polyethylene bearings. At the two-year follow-up, 444 patients (217 study group and 227 control group) were available for review. The clinical and radiographic outcomes between the groups were comparable, and reflected the typical results of primary total hip replacements. No complications related to spontaneous failures of the ceramic bearings were observed at this early follow-up period. Further follow-up is needed to confirm these findings over the long-term, but the short-term safety of alumina ceramic bearings in hip replacements reported in other recent reports is further validated by our findings. (Hip International 2005; 15: 129-35).

On-farm falls among youth less than 20 years old in the U.S.

This article examines the magnitude and characteristics of fall-related injuries on U.S. farms for youth less than 20 years old for work and non-work exposures at a national level. To examine the problem, data from the Childhood Agricultural Injury Survey (CAIS) and Census of Fatal Occupational Injuries (CFOI) were used. Findings indicate that falls are an important contributor to on-farm injuries, with youth appearing to be at considerable risk. Thus, a reduction of the exposure of youth to fall-related hazards on farms is needed. Strategies such as providing safe play areas for young children and continuing efforts to prevent extra riders on farm equipment will help in reducing these hazardous fall exposures.

Elution characteristics of tobramycin from polycaprolactone in a rabbit model.

This study investigated the elution characteristics of tobramycin from polycaprolactone, a bioabsorbable polymer, in a rabbit model. Sixty rabbits were divided into two groups. Group 1 had polycaprolactone rods impregnated with 6% tobramycin surgically implanted into the proximal femoral intramedullary canal. Group 2 received polymethylmethacrylate rods of like size, shape, and antibiotic concentration. Serum and urine samples were obtained, and tobramycin levels were determined via fluorescent immunosorbent assay. Rabbits were sacrificed as long as 56 days after surgery. Local bone tobramycin concentration was determined using the agar diffusion method. Polycaprolactone delivered a significantly higher peak bone concentration of tobramycin (22.4 microg/mL) than did polymethylmethacrylate (13.59 microg/mL). Polycaprolactone also had a more gradual decrease in local tobramycin concentration than did polymethylmethacrylate. Neither polycaprolactone nor polymethylmethacrylate yielded consistently detectable (> 0.1 microg/mL) serum tobramycin levels. Urine concentrations mirrored those seen in bone, with polycaprolactone achieving significantly higher tobramycin concentrations than did polymethylmethacrylate. Polycaprolactone had superior elution characteristics compared with polymethylmethacrylate in this lapine model, suggesting that polycaprolactone might be a promising local antibiotic delivery vehicle for the treatment of osteomyelitis.

Effects of hyperinsulinemia and obesity on risk of neural tube defects among Mexican Americans.

Although both maternal obesity and diabetes mellitus increase the risk for neural tube defects, it is unknown whether they are independent risk factors or manifestations of an underlying prediabetic state such as hyperinsulinemia. We investigated whether hyperinsulinemia was a risk factor for neural tube defects independent of obesity and hyperglycemia in Mexican-American women. We identified case and control women from residents delivering or terminating pregnancies in hospitals or birthing centers in any of the 14 Texas-Mexico border counties during 1995-2000. Case women had a pregnancy affected by anencephaly, spina bifida, or encephalocele; randomly selected control women had normal births, frequency matched by year and birth facility. Questionnaire and laboratory values obtained 5-6 weeks postpartum were available for 149 case and 178 control women. Both hyperinsulinemia and obesity were related to increased neural tube defect risk [odds ratio (OR) = 1.91, 95% confidence interval (CI) = 1.21-3.01 and OR = 1.73, 95% CI = 1.03-2.92, respectively]. Adjustment for obesity only slightly reduced the effect of hyperinsulinemia (OR = 1.75, 95% CI = 1.09-2.82). Alternatively, a modest effect remained for obesity after adjustment for hyperinsulinemia (OR = 1.45, 95% CI = 0.84-2.51). Hyperinsulinemia is a strong risk factor for neural tube defects and may be the driving force for the observed risk in obese women.

In vitro elution of tobramycin from bioabsorbable polycaprolactone beads.

OBJECTIVES: To compare the in vitro elution characteristics of tobramycin impregnated beads made of polycaprolactone (PCL) and polymethylmethacrylate (PMMA). DESIGN: Six-millimeter PCL and PMMA beads with 6% tobramycin were formed and placed in phosphate-buffered saline or newborn calf serum and incubated at room temperature or 37 degrees C. Aliquots were taken at intervals for eight weeks. Tobramycin levels were determined by fluorescent assay and antibacterial efficacy was assessed by measuring the zones of inhibition against Staphylococcus aureus and Pseudomonas aeruginosa on agar diffusion plates. RESULTS: Tobramycin elution rates at room temperature were similar up to three weeks. At three weeks, elution rates from PCL beads were twice those from PMMA beads, and at eight weeks, elution from PCL was quadruple that from PMMA. At 37 degrees C, tobramycin elution rates from PCL were eight times greater than those from PMMA by eight weeks. Total tobramycin eluted from PCL beads was 38.9% and 20% in PMMA beads. All samples showed bacteriostatic activity against S. aureus and P. aeruginosa at eight weeks. CONCLUSIONS: These in vitro results show that PCL has superior antibiotic elution characteristics compared with PMMA, and this may translate into a more effective antibiotic delivery vehicle. In addition, PCL is a bioabsorbable polymer, which may decrease the need for a second surgical procedure to remove retained beads.

Synergy between Staphylococcus aureus and Pseudomonas aeruginosa in a rat model of complex orthopaedic wounds.

BACKGROUND: We observed an interaction in animals inoculated concomitantly with Staphylococcus aureus and Pseudomonas aeruginosa during a study of the efficacy of surfactants for disinfection of orthopaedic wounds. This led us to investigate whether synergy could be demonstrated between Staphylococcus aureus and Pseudomonas aeruginosa in a rat model of complex orthopaedic wounds. METHODS: A wire was implanted into the spinous process of a lumbar vertebra of Sprague-Dawley rats through a dorsal incision. Animals were divided into two groups: group one was inoculated with either Staphylococcus aureus or Pseudomonas aeruginosa, and group two received a polymicrobial inoculation with both test organisms in varying concentrations. After inoculation, the wounds were irrigated and closed. On postoperative day 14, all animals were killed and specimens from the wounds were cultured. The number of colony-forming units (CFU) of Staphylococcus aureus or Pseudomonas aeruginosa needed to cause infection in 50% of the animals (ID50) was determined with use of the Reed-Muench method. The infection rate associated with each inoculum combination was calculated, and the two groups were compared. RESULTS: The ID50 was 2.8 x 10(4) CFU for Staphylococcus aureus and 4.8 x 10(5) CFU for Pseudomonas aeruginosa. The combination of 10(3) CFU of Staphylococcus aureus with low concentrations (10(2), 10(3), or 10(4) CFU) of Pseudomonas aeruginosa yielded infection rates that were higher than those found with either organism alone at the same concentrations. The combination of 10(3) CFU of Staphylococcus aureus and 10(3) CFU of Pseudomonas aeruginosa yielded a 75% infection rate, which was significantly higher (p = 0.004) than that associated with 10(3) CFU of either organism alone. As the Pseudomonas aeruginosa concentration was increased (to 10(5), 10(6), and 10(7) CFU), this trend reversed, and the infection rate decreased to 33% (p = 0.004). Low concentrations of Pseudomonas aeruginosa (0 to 10(5) CFU) combined with 10(6) CFU of Staphylococcus aureus yielded infection rates ranging from 83% to 100%. At the higher concentrations of Pseudomonas aeruginosa (10(6) and 10(7) CFU), however, the infection rate again decreased, to 33% (p = 0.005). Only Staphylococcus aureus was isolated from the cultures of the specimens from the animals that had received a polymicrobial inoculum. CONCLUSIONS: Synergy between Staphylococcus aureus and Pseudomonas aeruginosa was demonstrated when low levels of each organism were present in the wound. As the Pseudomonas aeruginosa concentration was increased, the infection rates fell well below what would be anticipated, suggesting that low concentrations of Pseudomonas aeruginosa enhance the ability of Staphylococcus aureus to cause infection in this orthopaedic wound model. At the same time, the presence of Staphylococcus aureus in the ratios tested decreased the rate of infection by Pseudomonas aeruginosa. CLINICAL RELEVANCE: Staphylococcus aureus is a pathogen commonly seen in orthopaedic patients. The pathogenicity of Staphylococcus aureus was shown to be increased in the presence of anaerobic bacteria. This study is the first one that we are aware of that demonstrated synergy between Staphylococcus aureus and Pseudomonas aeruginosa, at low concentrations, in a wound model while at the same time showing that Staphylococcus aureus lowers the rate of Pseudomonas aeruginosa infection.

Non-fatal animal related injuries to youth occurring on farms in the United States, 1998.

OBJECTIVE: To provide data on the magnitude and patterns of animal related on-farm injuries to youth in the United States. DATA SOURCE: A survey of 26,000 farm households conducted for the National Institute for Occupational Safety and Health by the United States Department of Agriculture in 1998. SUBJECTS: Youth younger than 20 years of age. RESULTS: There were an estimated 6,438 animal related on-farm injuries to youth in 1998. 70% occurred to farm residents; 69% were work related. Males accounted for 64% and approximately 41% occurred to those younger than 10; 37% involved horses and 31% cattle. Most horse related injuries occurred to females and a majority of the cattle related injuries were to males. Additionally, most of the cattle related injuries were work related, while horse related injuries were mainly nonwork. CONCLUSIONS: One out of every five youth injuries occurring on farms in the United States is animal related. These animal related injuries were due to both work and non-work related exposures. The large number of horse and cattle related injuries highlights a need for intervention strategies based on the injury circumstances common to these animals.

Neural tube defects among Mexican Americans living on the US-Mexico border: effects of folic acid and dietary folate.

Populations of Mexican descent have high occurrences of neural tube defects (NTDs). A recent study suggested that folic acid supplements may not protect these populations from NTDs. In a case-control study, the authors investigated the role of folic acid and dietary folate intake in NTD risk among Mexican Americans living along the Texas-Mexico border. From January 1995 to February 1999, 148 Mexican-American women with NTD-affected pregnancies and 158 women with normal live births were interviewed in person about use of vitamin supplements and dietary intakes during a 6-month periconceptional period (from 3 months before conception to 3 months after conception). Daily preconceptional consumption of vitamin supplements containing folic acid was 2.5% in control women and 2.0% in case women (odds ratio = 0.77; 95% confidence interval (CI): 0.19, 3.22). With adjustment for maternal age, education, obesity, and previous stillbirth or miscarriage, the risk estimate was essentially null (odds ratio = 1.12; 95% CI: 0.22, 5.78). Combined folic acid intake from diet and supplements showed only a modest risk reduction for intakes of > or = 1.0 mg per day (adjusted odds ratio = 0.73; 95% CI: 0.31, 1.72). The fact that the primary folic acid exposure was in the form of dietary polyglutamates rather than the more easily absorbed supplemental monoglutamates may explain an apparent decreased effect in this population.

BRG1, a component of the SWI-SNF complex, is mutated in multiple human tumor cell lines.

Human BRG1 is a component of the evolutionarily conserved SWI-SNF chromatin remodeling complex. BRG1 has been implicated in growth control through its interaction with the tumor suppressor pRb and may consequently serve as a negative regulator of proliferation. Postulating that BRG1 may itself be a tumor suppressor gene, we screened a panel of tumor cell lines to determine whether the gene is targeted for mutation. We report that the COOH-terminal region of BRG1 is homozygously deleted in two carcinoma cell lines, prostate TSU-Pr1 and lung A-427. In addition, biallelic inactivations of BRG1 were observed in four other cell lines derived from carcinomas of the breast, lung, pancreas, and prostate; their mutations in BRG1 included three frameshift lesions and one nonsense lesion. Point mutations were also discovered in a number of other cell lines, however in most cases any effect of these mutations on BRG1 function remains to be established. A variety of different mutations within BRG1, in several cell lines, suggest that BRG1 may be targeted for disruption in human tumors. Significantly, reintroduction of BRG1 into cells lacking BRG1 expression was sufficient to reverse their transformed phenotype inducing growth arrest and a flattened morphology. These data strongly support the model that BRG1 may function as a tumor suppressor and strengthen the hypothesis that the regulation of gene expression through chromatin remodeling is critical for cancer progression. It will be important to confirm these observations in primary tumors.