Discovery of novel cell wall-active compounds using P ywaC, a sensitive reporter of cell wall stress, in the model gram-positive bacterium Bacillus subtilis.

The emergence of antibiotic resistance in recent years has radically reduced the clinical efficacy of many antibacterial treatments and now poses a significant threat to public health. One of the earliest studied well-validated targets for antimicrobial discovery is the bacterial cell wall. The essential nature of this pathway, its conservation among bacterial pathogens, and its absence in human biology have made cell wall synthesis an attractive pathway for new antibiotic drug discovery. Herein, we describe a highly sensitive screening methodology for identifying chemical agents that perturb cell wall synthesis, using the model of the Gram-positive bacterium Bacillus subtilis. We report on a cell-based pilot screen of 26,000 small molecules to look for cell wall-active chemicals in real time using an autonomous luminescence gene cluster driven by the promoter of ywaC, which encodes a guanosine tetra(penta)phosphate synthetase that is expressed under cell wall stress. The promoter-reporter system was generally much more sensitive than growth inhibition testing and responded almost exclusively to cell wall-active antibiotics. Follow-up testing of the compounds from the pilot screen with secondary assays to verify the mechanism of action led to the discovery of 9 novel cell wall-active compounds.

Elevated plasmz zinc: a heritable anomaly.

An extremely high concentration of zinc in the plasma (hyperzincemia) was found in five out of seven members of one family and in two out of three second generation indiviuals, an indication that the condition is heritable. The excess zinc in the plasma appears to be bound to serum proteins, with no apparent clinical symptoms or abnormalities.

Helicobacter pylori physiology predicted from genomic comparison of two strains.

Helicobacter pylori is a gram-negative bacteria which colonizes the gastric mucosa of humans and is implicated in a wide range of gastroduodenal diseases. This paper reviews the physiology of this bacterium as predicted from the sequenced genomes of two unrelated strains and reconciles these predictions with the literature. In general, the predicted capabilities are in good agreement with reported experimental observations. H. pylori is limited in carbohydrate utilization and will use amino acids, for which it has transporter systems, as sources of carbon. Energy can be generated by fermentation, and the bacterium possesses components necessary for both aerobic and anaerobic respiration. Sulfur metabolism is limited, whereas nitrogen metabolism is extensive. There is active uptake of DNA via transformation and ample restriction-modification activities. The cell contains numerous outer membrane proteins, some of which are porins or involved in iron uptake. Some of these outer membrane proteins and the lipopolysaccharide may be regulated by a slipped-strand repair mechanism which probably results in phase variation and plays a role in colonization. In contrast to a commonly held belief that H. pylori is a very diverse species, few differences were predicted in the physiology of these two unrelated strains, indicating that host and environmental factors probably play a significant role in the outcome of H. pylori-related disease.

Membrane activity profiling of small molecule B. subtilis growth inhibitors utilizing novel duel-dye fluorescence assay.

Small molecule disruption of the bacterial membrane is both a challenge and interest for drug development. While some avoid membrane activity due to toxicity issues, others are interested in leveraging the effects for new treatments. Existing assays are available for measuring disruption of membrane potential or membrane permeability, two key characteristics of the bacterial membrane, however they are limited in their ability to distinguish between these properties. Here, we demonstrate a high throughput assay for detection and characterization of membrane active compounds. The assay distinguishes the effect of small molecules on either the membrane potential or membrane permeability using the fluorescent dyes TO-PRO-3 iodide and DiOC2(3) without the need for secondary assays. We then applied this assay to a library of 3520 synthetic molecules previously shown to inhibit growth of B. subtilis in order to determine the frequency of membrane activity within such a biologically active library. From the library, we found 249 compounds that demonstrated significant membrane activity, suggesting that synthetic libraries of this kind do not contain a plurality of membrane active molecules.

Serum hormones and the alcohol-breast cancer association in postmenopausal women.

BACKGROUND: Alcohol ingestion is associated with an increased risk of breast cancer in most epidemiologic studies. Results, however, are heterogeneous at lower levels of alcohol intake, and a biologic mechanism for the association has not been clearly identified. To determine whether alcohol consumption by postmenopausal women elevates serum levels of hormones associated with an increased risk of breast cancer, we performed a controlled feeding study. METHODS: Participants were 51 healthy postmenopausal women not using hormone replacement therapy. Each participant rotated through three 8-week dietary periods in which she consumed 15 or 30 g of alcohol per day or an alcohol-free placebo beverage. The order of assignment to the three alcohol levels was random. During the dietary periods, all food and beverages were supplied by the study, and energy intake was adjusted to keep body weight constant. Levels of estradiol, estrone, estrone sulfate, testosterone, androstenedione, progesterone, dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), and androstenediol were measured by radioimmunoassays in serum collected at the end of each dietary period. All statistical tests are two-sided. RESULTS: When women consumed 15 or 30 g of alcohol per day, respectively, estrone sulfate concentrations increased by 7.5% (95% confidence interval [CI] = -0.3% to 15.9%; P =.06) and 10.7% (95% CI = 2.7% to 19.3%; P =.009) and DHEAS concentrations increased by 5.1% (95% CI = 1.4% to 9.0%; P =.008) and 7.5% (95% CI = 3.7% to 11.5%; P<.001) relative to levels when women consumed placebo. None of the other hormones measured changed statistically significantly when women consumed alcohol. CONCLUSIONS: Results suggest a possible mechanism by which consumption of one or two alcoholic drinks per day by postmenopausal women could increase their risk of breast cancer.

High concentrations of the carcinogen 2-amino-1-methyl-6-phenylimidazo- [4,5-b]pyridine (PhIP) occur in chicken but are dependent on the cooking method.

Heterocyclic aromatic amines (HAAs) are mutagenic and carcinogenic compounds found in meats cooked at high temperatures. Although chicken is consumed in large quantities in the United States, there is little information on its HAA content. The objective of this study was to measure the five predominant HAAs (IQ, MeIQ, MeIQx, DiMeIQx, and PhIP) in chicken cooked by various methods to different degrees of doneness. Chicken breasts were panfried, oven-broiled, or grilled/barbecued. Whole chickens were roasted or stewed. Skinless, boneless chicken breasts were cooked to three degrees of doneness: just until done, well done, or very well done. High levels of PhIP (ranging from 12 to 480 ng/g cooked meat) were found in chicken breasts when panfried, oven-broiled, and grilled/barbecued but not in while roasted or stewed chicken. PhIP concentration increased in skinless, boneless chicken breast with longer cooking time, higher internal temperature, and greater degree of surface browning. PhIP concentration was also high in chicken breasts cooked with skin and bones. MeIQx and DiMeIQx levels increased with the degree of doneness, whereas IQ and MeIQ were not detectable in any of these chicken samples. Certain cooking methods produce PhIP, a known colon and breast carcinogen in rodents and possibly a human carcinogen, at substantially higher levels in chicken than has been reported previously in red meat.

Pan-fried meat containing high levels of heterocyclic aromatic amines but low levels of polycyclic aromatic hydrocarbons induces cytochrome P4501A2 activity in humans.

Heterocyclic aromatic amines (HAAs) are formed when meat juices are pyrolyzed. In humans HAAs are activated in vivo by cytochrome P4501A2 (CYP1A2) and N-acetyltransferase (NAT2) to mutagens or carcinogens. While activity of NAT2 is noninducible, exposure to cigarettes, polycyclic aromatic hydrocarbons, and cruciferous vegetables has been shown to induce CYP1A2 activity in humans. To date, it is unknown if pan-fried meat, which is consumed at high levels in the United States, is capable of inducing CYP1A2. In order to address this issue, we measured CYP1A2 and NAT2 activities in 66 healthy nonsmokers (33 males and 33 females) in a controlled metabolic feeding study. The study was designed to minimize the influence of known inducers of CYP1A2. Subjects consumed meat pan-fried at a low temperature (100 degrees C) for 7 days followed by 7 days of meat pan-fried at a high temperature (250 degrees C). The low temperature-cooked meat had undetectable levels of HAAs while the high temperature-cooked meat contained high amounts of HAAs [9.0 ng/g of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2.1 ng/g of 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (DiMeIQx), and 32.8 ng/g of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)]. In contrast, total polycyclic aromatic hydrocarbon content was similar in both meat samples (10.7 ng/g in low temperature-cooked meat and 10.1 ng/g in high temperature-cooked meat). At the end of each period, subjects were tested for CYP1A2 and NAT2 enzyme activity by caffeine metabolism phenotyping. NAT2 activity remained unchanged throughout the study while CYP1A2 activity increased in 47 of 65 (72%) of the subjects after consuming high temperature-cooked meat (P < 0.0002), suggesting induction by some compound(s) formed during high temperature cooking. If HAAs are shown to be human carcinogens in epidemiological studies, then meat cooked at high temperatures may pose an increased cancer risk because it contains both inducers of CYP1A2 and procarcinogens MeIQx, DiMeIQx, and PhIP known to be activated by this enzyme.

A kinetic and equilibrium study of the denaturation of aspartic proteinases from the fungi, Endothia parasitica and Mucor miehei.

Kinetic and equilibrium analyses of the denaturation of Endothia parasitica and Mucor miehei aspartic proteinases were performed using enzyme activity and ultraviolet absorption as indices of denaturation. Denaturation of these proteinases was shown to be irreversible, suggesting that the conformations of these aspartic proteinases may be predetermined in their zymogens. Thermal and guanidine hydrochloride denaturation of these proteinases produced first-order, two-state, kinetic behaviour. Equilibrium unfolding transitions of these proteinases were highly cooperative but not entirely coincident in the two indices employed, suggesting some deviation from two-state character. Oxidation to remove 37.8% of the carbohydrate of M. miehei glycoproteinase with sodium metaperiodate resulted in a substantial decrease in both kinetic and equilibrium stabilities without modification of the amino acid composition or specific activity. In addition, gel filtration subsequent to equilibrium studies indicated that partial removal of the carbohydrate from M. miehei proteinase promoted autolysis under denaturing conditions.

The dependence of the lipolytic activity of Rhizopus arrhizus lipase on surfactant concentration in Aerosol-OT/isooctane reverse micelles and its relationship to enzyme structure.

Aerosol OT, bis(2-ethylhexyl)sodium sulfosuccinate/isooctane reverse micelles were used to investigate the dependence of the lipolytic activity of Rhizopus arrhizus lipase on surfactant concentration. Kinetic constants for the lipolytic reaction were measured in parallel with structural studies using protein fluorescence and circular dichroism (CD) spectroscopy. Km values remained constant throughout the range of AOT concentrations studied. The kcat values decreased with increasing surfactant concentration at constant water-to-surfactant ratio (wo = 11) from 50 mM to 100 mM AOT, but remained constant from 100 to 200 mM AOT. These data suggested an association of the lipase with the micellar membrane. An inflection in the time-course of the reaction was found to be a function of both surfactant and substrate concentrations and was likely an indication of the interfacial nature of the hydrolysis reaction. Structure prediction based on far-UV CD spectral data demonstrated structural reorganization of R. arrhizus lipase upon incorporation into reverse micelles which was characterized by a dramatic increase in beta-sheet and overall accountable secondary structure. Other spectral changes of the lipase upon incorporation into reverse micelles included appearance of fine structure in the near-UV CD spectrum and a blue shift in the fluorescence emission maximum from 336 to 326 nm.

Pulmonary infiltrates following butane 'fire-breathing'.

Rapidly progressive bilateral pulmonary infiltrates occurred in a 19-year-old man following an unusual hydrocarbon abuse. The acute illness was the result of a "trick" known as "fire-breathing." Fire-breathing involves filling the oral cavity with butane gas, from an ordinary butane cigarette/cigar lighter, and exhalation of the volatile vapors over an open flame producing a flame-throwing effect. Because of the pulmonary toxic reaction, this activity could have a serious or even fatal outcome.

Sleep fragmentation in the elderly: relationship to daytime sleep tendency.

Sleep in the elderly is known to be disturbed, and many elderly persons also complain of daytime sleepiness. The present study assessed sleep and waking behavior in 12 male (aged 63 to 86) and 12 female (ages 63 to 82) subjects. Sleep stages, respiration, and movement were recorded at night, and daytime sleep tendency was measured using the Multiple Sleep Latency Test during a single 24-hour period. Daytime sleepiness did not correlate with total sleep time or any sleep stage, but was significantly correlated with measures of sleep fragmentation. The latter included transient arousals, a measure of less than 15-sec awakenings, and sleep-related respiration disturbance. These findings suggest that fragmented nocturnal sleep is a significant cause of reduced daytime well-being in elderly individuals. The continuity of both sleep and wakefulness appears to be disrupted with age. Experimental strategies for achieving a rational sleep hygiene are discussed.

Carotenodermia in men with elevated carotenoid intake from foods and beta-carotene supplements.

We evaluated the relation between plasma levels of carotenoids and carotenodermia in 30 men receiving carotenoid supplementation for 42 d. Five subjects each were randomly assigned to one of six treatment groups: 30 mg purified beta-carotene supplement, 12 mg beta-carotene supplement, 272 g cooked carrots, 300 g cooked broccoli, 180 g tomato juice, and placebo. Definite carotenodermia was observed only in the five subjects who took 30 mg of purified beta-carotene daily. Carotenodermia was first noted between 25 and 42 d after supplementation and persisted from 14 to greater than 42 d posttreatment and was observed only after plasma total carotenoid levels exceeded 4.0 mg/L. These observations may be useful to investigators planning clinical trials with beta-carotene and to clinicians assessing the significance of carotenodermia in men taking beta-carotene supplements or following diets high in carotenoid-containing foods.

Carotenoids in human buccal mucosa cells after 4 wk of supplementation with tomato juice or lycopene supplements.

BACKGROUND: Lycopene has been identified as a phytochemical with potentially protective health benefits. OBJECTIVE: Our objective was to monitor lycopene changes in buccal mucosa cells (BMCs) in response to 3 vehicles for oral delivery of lycopene. DESIGN: Fifteen healthy subjects ingested lycopene-rich tomato juice, tomato oleoresin, lycopene beadlets (each containing 70-75 mg lycopene) and a placebo for 4 wk each in a randomized crossover design while consuming self-selected diets. A 6-wk washout period separated the treatment periods. BMCs were collected at baseline and after 4 wk of supplementation. RESULTS: Lycopene in BMCs increased significantly ( approximately 2-fold) after 4 wk of ingestion of oleoresin and of beadlets to 4.95 (P < 0.001) and 3.75 microg/g protein (P = 0.053), respectively, but was not significantly affected by tomato juice treatment. The placebo treatment produced a significant decrease in BMC lycopene concentrations (P = 0.018). We observed significant treatment differences between oleoresin and tomato juice, oleoresin and placebo, and beadlets and placebo. BMC concentrations of phytofluene and beta-carotene, which were present in small amounts in the lycopene-containing treatments, increased significantly with ingestion of these products. Strong correlations were found between plasma and BMC concentrations of lutein, beta-cryptoxanthin, alpha-carotene, and beta-carotene. In contrast, correlations between lycopene concentrations in plasma and in BMCs were weak and not significant for any treatment. CONCLUSIONS: The cellular content of lycopene and other tomato-related carotenoids with proposed beneficial health effects can be increased through prolonged supplementation.

Plasma carotenoids in normal men after a single ingestion of vegetables or purified beta-carotene.

Changes in seven plasma carotenoids were measured in 30 men for 11 d after ingesting a single dose of pure beta-carotene or a high carotenoid vegetable. A controlled, low-carotenoid diet was fed in a crossover design. Maximum plasma concentrations of beta-carotene occurred 24-48 h after dosing with beta-carotene (12 or 30 mg) or carrots (270 g). A large intake of broccoli (600 g) or tomato juice (180 g) did not change any plasma carotenoids. We concluded that 1) normal subjects vary widely, three to fourfold, in efficiency of carotenoid absorption; 2) peak plasma response to beta-carotene in a capsule occurs at 24-48 h; 3) a large single intake of carrots produces a small increase in plasma beta-carotene but single intakes of broccoli or tomato juice do not change plasma carotenoids; and 4) plasma response to pure beta-carotene is greater than the response to a similar amount of beta-carotene in carrots.

Plasma carotenoid response to chronic intake of selected foods and beta-carotene supplements in men.

We determined serial changes in four major plasma carotenoid fractions (alpha-carotene, beta-carotene, lutein/zeaxanthin, and lycopene) in 30 men consuming defined daily doses of carotenoids from foods (broccoli, carrots, or tomato juice) or from purified beta-carotene in capsules (12 or 30 mg) for 6 wk while fed a controlled diet. Compared with baseline, beta-carotene increased in the 30- and 12-mg-capsule and carrot groups whereas alpha-carotene increased in the carrot group and lutein increased in the broccoli group. Lower lutein concentrations in recipients of beta-carotene capsules suggested an interaction between these two carotenoids. Lycopene declined in all groups except the tomato-juice group. Total carotenoid concentration changes only reflected the large increases in beta-carotene concentrations and not the smaller changes observed in other individual carotenoids. Overall, purified beta-carotene produced a greater plasma response than did similar quantities of carotenoids from foods sources. However, some foods increased plasma concentrations of certain carotenoids.

Chronic ingestion of lycopene-rich tomato juice or lycopene supplements significantly increases plasma concentrations of lycopene and related tomato carotenoids in humans.

The bioavailability of lycopene from tomato juice and 2 dietary supplements, each containing 70-75 mg lycopene, was studied in 15 healthy volunteers in a randomized, crossover design. Subjects ingested lycopene-rich tomato juice, tomato oleoresin, lycopene beadlets, and a placebo for 4 wk each while consuming self-selected diets. Treatment periods were separated by 6-wk washout periods. Plasma lycopene concentrations, assessed at baseline and weekly throughout the treatment periods, were significantly higher during tomato juice, oleoresin, and lycopene beadlet ingestion than during placebo ingestion. Mean (+/-SEM) increases in plasma lycopene at week 4 of tomato juice, oleoresin, and lycopene beadlet ingestion were not significantly different: 0.24 +/- 0.07, 0.23 +/- 0.05, and 0.24 +/- 0.06 micromol/L, respectively. Plasma concentrations of phytofluene and phytoene, which were present in small amounts in tomato juice, oleoresin, and lycopene beadlets, increased significantly with ingestion of these 3 products. Beta-carotene, zeta-carotene, and 2,6-cyclolycopene-1,5-diol (a metabolite of lycopene)--also present in tomato juice and supplements--were significantly increased with consumption of the tomato juice and lycopene beadlets, but not with oleoresin consumption. A marked increase in plasma concentrations of an unknown compound was observed; it was detected in trace amounts in tomato juice, oleoresin, and lycopene beadlets, and had a maximum absorbance at 448 nm and a molecular weight of 556. Concentrations of plasma lycopene and other carotenoids with potential for enhancing human health can be increased by ingestion of realistic amounts of tomato juice. Lycopene appears to be equally bioavailable from tomato juice and the supplements used in this study.

The correlation between two dietary assessments of carotenoid intake and plasma carotenoid concentrations: application of a carotenoid food-composition database.

A newly available carotenoid food-composition database providing specific carotenoid values for > 2300 foods was linked to dietary data on 57 male nonsmokers to examine the association between dietary carotenoid intake and plasma carotenoid concentrations over 3 wk when free-living. Carotenoid intake was estimated from a food-frequency questionnaire (FFQ) and 7 d of food diaries with concurrent analysis of plasma carotenoid concentrations. After adjustment for energy intake, percentage of energy from alcohol, and plasma lipid concentrations, significant diet-plasma correlations for the FFQ and the food diaries (FD) included alpha-carotene (r = 0.29 and 0.43), beta-carotene (r = 0.36 FFQ only), beta-cryptoxanthin (r = 0.46 and 0.44), lutein (r = 0.44 FD only), and lycopene (r = 0.53 FD only). Dietary carotenoid intakes were associated with plasma carotenoid concentrations for all the carotenoids except for beta-carotene when food diaries were used whereas the diet-plasma correlation for the provitamin A carotenoids were consistently significant when the FFQ was used.

Treatment of obstructive sleep apnea with continuous nasal airflow delivered through nasal prongs.

We describe a new device for treating obstructive sleep apnea (OSA) which is similar to nasal CPAP, but less cumbersome. The device consists of a 7 mm diameter flexible tube terminating at one end in nasal prongs covered with foam cylinders. The foam cylinders are compressed, inserted into the nostrils and released, forming a tight seal. The other end of the catheter is attached to a compressor delivering between 7 and 15 L/min of air. We studied four men and two women with OSA, the first night without treatment and the following night with continuous nasal airflow. A desaturation index was calculated by multiplying the average number of desaturation episodes per hour of sleep times the average maximum desaturation per episode. With continuous nasal airflow there was a significant decrease in all parameters (p less than .025). We conclude that continuous nasal airflow decreased oxyhemoglobin desaturation in patients with OSA and may be useful in patients with mild-to-moderate OSA and in patients who do not tolerate nasal CPAP.

Zinc in selected hospital diets. Comparison of analysis vs. calculation.

Sample hospital meals for breakfast and the noon and evening meals for regular, ovo-lacto-vegetarian, and renal diets were collected for seven consecutive days. The daily zinc content of each diet was determined, using atomic absorption spectrophotometric analysis and by calculation, using the USDA provisional tables on the zinc content of individual foods. The data indicated that the provisional tables provide a reasonable estimation of zinc content of regular or renal diets with errors approximately 10%. However, a 35% overestimation occurred for vegetarian diets. A major cause of error between assayed and calculated values was probably due to substituting items not included in the tables. The mean zinc content for the regular diet, as offered, was 97% of the adult recommended allowance for zinc, while the vegetarian diet provided 81% of the allowance. The average renal diet contained 49% of the allowance. Certain types of vegetarian and low-protein diets may be inadequate in total and/or available zinc. Also important in evaluating hospital diets for adequacy of zinc are the actual intake and the condition of the patient.

Effects of moderate alcohol consumption on folate and vitamin B(12) status in postmenopausal women.

BACKGROUND: Although alcohol intake has been positively associated with breast cancer risk in epidemiologic studies, a causal relationship has not been established, and the mechanisms mediating this association are speculative. Alcohol may act through altered status of folate and vitamin B(12), two vitamins required for DNA methylation and nucleotide synthesis, and thus cell integrity. Although the effects of heavy alcohol intake on folate and vitamin B(12) status have been well-documented, few studies have addressed the effects of moderate alcohol intake in a controlled setting. OBJECTIVE: The objective of this study was to determine the effects of moderate alcohol intake on folate and vitamin B(12) status in healthy, well-nourished, postmenopausal women. DESIGN: The study design was a randomized, diet-controlled crossover intervention. Postmenopausal women (n=53) received three 8-week alcohol treatments in random order: 0, 15, and 30 g/day. Treatment periods were preceded by 2-5-week washout periods. Blood collected at baseline and week 8 of each treatment period was analyzed for serum folate, vitamin B(12), homocysteine (HCY), and methylmalonic acid (MMA) concentrations. RESULTS: After adjusting for body mass index (BMI), a significant 5% decrease was observed in mean serum vitamin B(12) concentrations from 0 to 30 g of alcohol/day (461.45+/-30.26 vs 440.25+/-30.24 pg/ml; P=0.03). Mean serum HCY concentrations tended to increase by 3% from 0 to 30 g of alcohol/day (9.44+/-0.37 vs 9.73+/-0.37 micromol/l; P=0.05). Alcohol intake had no significant effects on serum folate or MMA concentrations. CONCLUSIONS: Among healthy, well-nourished, postmenopausal women, moderate alcohol intake may diminish vitamin B(12) status.