Bactericidal efficacy of hydrogen peroxide on Cutibacterium acnes.

OBJECTIVES: The purpose of this study was to examine the bactericidal efficacy of hydrogen peroxide (H2O2) on Cutibacterium acnes (C. acnes). We hypothesize that H2O2 reduces the bacterial burden of C. acnes. METHODS: The effect of H2O2 was assessed by testing bactericidal effect, time course analysis, growth inhibition, and minimum bactericidal concentration. To assess the bactericidal effect, bacteria were treated for 30 minutes with 0%, 1%, 3%, 4%, 6%, 8%, or 10% H2O2 in saline or water and compared with 3% topical H2O2 solution. For time course analysis, bacteria were treated with water or saline (controls), 3% H2O2 in water, 3% H2O2 in saline, or 3% topical solution for 5, 10, 15, 20, and 30 minutes. Results were analyzed with a two-way analysis of variance (ANOVA) (p < 0.05). RESULTS: Minimum inhibitory concentration of H2O2 after 30 minutes is 1% for H2O2 prepared in saline and water. The 3% topical solution was as effective when compared with the 1% H2O2 prepared in saline or water. The controls of both saline and water showed no reduction of bacteria. After five minutes of exposure, all mixtures of H2O2 reduced the percentage of live bacteria, with the topical solution being most effective (p < 0.0001). Maximum growth inhibition was achieved with topical 3% H2O2. CONCLUSION: The inexpensive and commercially available topical solution of 3% H2O2 demonstrated superior bactericidal effect as observed in the minimum bactericidal inhibitory concentration, time course, and colony-forming unit (CFU) inhibition assays. These results support the use of topical 3% H2O2 for five minutes before surgical skin preparation prior to shoulder surgery to achieve eradication of C. acnes for the skin.Cite this article: P. Hernandez, B. Sager, A. Fa, T. Liang, C. Lozano, M. Khazzam. Bactericidal efficacy of hydrogen peroxide on Cutibacterium acnes. Bone Joint Res 2019;8:3-10. DOI: 10.1302/2046-3758.81.BJR-2018-0145.R1.

Effect of lifestyle changes on whole-body protein turnover in obese adolescents.

OBJECTIVE: To investigate the effect of lifestyle changes on whole-body protein turnover (WBPT) in obese adolescents. DESIGN/METHODS: Randomized and controlled nonpharmacological intervention study of WBPT in obese adolescents using stable isotope dilution techniques. SUBJECTS AND MEASUREMENTS: We studied a total of 21 adolescents (11 boys and 10 girls, matched for their pubertal status) of which 15 were obese (age=15.8+/-0.4 y old and BMI=38.6+/-3.3 kg/m(2)) and six were lean controls (age=16.0+/-0.4 y old and BMI=21.3+/-1.2 kg/m(2)). The obese subjects were subjected to a randomized controlled lifestyle intervention program that involved moderate physical activity and diet changes for 3 months. A group of lean age-matched subjects was also studied at baseline to compare the WBPT in obese and lean adolescents. The studies were performed during a primed, continuous infusion of L-[1-(13)C]leucine. Leucine appearance rate (Leu Ra) was used as an index of whole protein breakdown and the nonoxidative portion of leucine disposal (NOLD) as an index of whole-body protein synthesis. RESULTS: The obese groups showed significantly higher body mass index (BMI), fat mass (FM), percent body fat (%BF), fat-free mass (FFM), resting energy expenditure (REE) and WBPT compared to the lean controls. The intervention program resulted in a redistribution of the parameters of body composition without apparent changes in BMI or body weight. There was a significant decrease in WBPT in the obese intervention group, but not in the obese control group. Insulin levels also decreased significantly in the obese group after intervention but not in the obese control group, whereas the glucose concentrations remained normal in all groups at baseline and also after intervention/or control. CONCLUSIONS: Results from the current study suggest: (i). abonormalities of protein metabolism occur early in the clinical course of obesity and (ii). these abnormalities are modifiable by moderate lifestyle changes in obese adolescents. The mechanism for these changes in WBPT in obese adolescents as well as their impact on specific cardiovascular risk factors and turnover of specific proteins will require further investigation.

Phenylbutyrate-induced glutamine depletion in humans: effect on leucine metabolism.

The present study was designed to determine whether sodium phenylbutyrate (phi B) acutely induces a decrease in plasma glutamine in healthy humans, and, if so, will decrease estimates of whole body protein synthesis. In a first group of three healthy subjects, graded doses (0, 0.18, and 0.36 g.kg-1.day-1) of phi B were administered for 24 h before study: postabsorptive plasma glutamine concentration declined in a dose-dependent manner, achieving an approximately 25% decline for a dose of 0.36 g phi B.kg-1.day-1. A second group of six healthy adults received 5-h infusions of L-[1-14C]leucine and L-[1-13C]glutamine in the postabsorptive state on two separate days: 1) under baseline conditions and 2) after 24 h of oral treatment with phi B (0.36 g.kg-1.day-1) in a randomized order. The 24-h phenylbutyrate treatment was associated with 1) an approximately 26% decline in plasma glutamine concentration from 514 +/- 24 to 380 +/- 15 microM (means +/- SE; P < 0.01 with paired t-test) with no change in glutamine appearance rate or de novo synthesis; 2) no change in leucine appearance rate (Ra), an index of protein breakdown (123 +/- 7 vs. 117 +/- 5 mumol.kg-1.h-1; not significant); 3) an approximately 22% rise in leucine oxidation (Ox) from 23 +/- 2 to 28 +/- 2 mumol.kg-1.h-1 (P < 0.01), resulting in an approximately 11% decline in nonoxidative leucine disposal (NOLD = Ra-Ox), an index of protein synthesis, from 100 +/- 6 to 89 +/- 5 mumol.kg-1.h-1 (P < 0.05). The data suggest that, in healthy adults, 1) large doses of oral phenylbutyrate can be used as a "glutamine trap" to create a model of glutamine depletion; 2) a moderate decline in plasma glutamine does not enhance rates of endogenous glutamine production; and 3) a short-term depletion of plasma glutamine decrease estimates of whole body protein synthesis.

Glutamine metabolism in very low birth weight infants.

To quantitate glutamine kinetics in premature infants and determine whether glutamine affects leucine metabolism. 11 very low birth weight (< 1250 g) neonates received 4-h i.v. infusions of L-[2H3]leucine and L-[13C5]glutamine, along with orogastric infusion of L-[I-13C]leucine and L-[I-13C]glutamine on the 10th d of life and in the fed state. Patients were receiving parenteral nutrition and were randomized to receive either hypocaloric, enteral preterm formula alone (controls; n = 5), or glutamine (0.2 g.kg-1.d-1 on the day of the study) supplemented formula (GL.n; n = 6). The rates of appearance (Ra) of leucine and glutamine, and their rates of splanchnic extraction were determined from isotopic enrichments in plasma at steady state. Leucine release from protein breakdown did not differ between groups (123 +/- 51 versus 162 +/- 94 mumol.kg-1h-1 in the controls and GLN group, respectively). Glutamine de novo synthesis accounted for > 80% of overall glutamine Ra, and was similar in both groups (626 +/- 177 versus 525 +/- 86 mumol.kg-1.h-1; NS); 46 +/- 16% and 53 +/- 31% of the enteral glutamine underwent first-pass splanchnic extraction in the controls and GLN group, respectively. These findings indicate that the pathways of glutamine de novo synthesis and glutamine utilization in the splanchnic bed are functional in very low birth weight humans by the 10th d of life. Glutamine supplementation provided at low doses on a hypocaloric regimen results in no apparent differences in flux of glutamine or leucine.

Disease management: a practitioner's perspective.

Disease management focuses on the patient throughout the entire course of a disease, measuring desired outcomes related to the patient and each intervention. Traditional health care based on cost component management does little to reduce the long-term costs of chronic illness. Hypertension is an appropriate target for disease management. Successful disease management will require integrated information systems and third party payer support.

Protein and energy metabolism in prepubertal children with sickle cell anemia.

We hypothesized that, in children with homozygous sickle cell anemia (HbSS), the shortened life-span of erythrocytes places an increased demand on protein stores, accelerates whole body protein turnover, and consequently, energy expenditure, as well as the rate of utilization of glutamine, a major fuel for reticulocytes. Eight (11.2 +/- 0.4 y old) children with HbSS who were free of infection of vaso-occlusive disease, and seven (11.3 +/- 0.4 y old) healthy black children were therefore studied in the postabsorptive state. Each received a continuous 4-h infusion of L-[1-(13)C]leucine to determine the rate of leucine oxidation, leucine rate of appearance, and nonoxidative leucine disposal, indicators of whole body protein breakdown and synthesis, respectively. Infusion of L-[2-(15)N]glutamine was used to assess rates of glutamine utilization. Resting energy expenditure and cardiac output were measured using indirect calorimetry and echocardiography, respectively. Compared with control subjects, HbSS children had a 58 and 65% higher leucine rate of appearance and nonxidative leucine disposal, respectively (both p < 0.001), 47% higher rates of whole body glutamine utilization (p < 0.01), 19% higher resting energy expenditure (p < 0.05), and 66% higher cardiac output (p < 0.01). In conclusion, children with HbSS show evidence of hypermetabolism with regard to protein, energy, and glutamine utilization. Both increased Hb synthesis and increased cardiac workload may contribute to excess protein and energy utilization. Whatever the mechanism of hypermetabolism, the data suggest that children with HbSS may have greater protein and energy requirements than the general population.

Response of glutamine metabolism to exogenous glutamine in humans.

To determine whether exogenous glutamine affects whole body glutamine metabolism, preliminary experiments were performed to verify that L-[1-13C]-, L-[U-14C]-, and L-[3,4-3H]glutamine given simultaneously by vein provided similar estimates of glutamine appearance rates [Ra; 355 +/- 24, 373 +/- 19, and 393 +/- 24 (SE) mumol.kg-1.h-1, respectively, P = NS] in six healthy men; glutamine oxidation accounted for 32 +/- 3 and 51 +/- 5% (P < 0.01) of glutamine Ra when it was measured using L-[U-14C]- and L-[1-13C]glutamine, respectively. Five subjects received two 5-h intravenous infusions of L-[3,4-3H]glutamine and a simultaneous nasogastric infusion of L-[1-13C]glutamine on 2 separate days in the postabsorptive state, along with saline on 1 day and natural L-glutamine (856 +/- 45 mumol.kg-1.h-1) on another day in a randomized order. Splanchnic glutamine extraction (determined from [13C]glutamine appearance into systemic blood) reached 74 +/- 4 and 53 +/- 5% during the enteral infusion of tracer alone and in combination with a large load of glutamine, respectively. Glutamine infusion was associated with increased plasma glutamine concentration (from 630 +/- 50 to 1,297 +/- 75 microM), Ra (from 258 +/- 20 to 589 +/- 45 mumol.kg-1.h-1), and oxidation (from 179 +/- 20 to 477 +/- 47 mumol.kg-1.h-1, all P < 0.01), no change in glutamine release from proteolysis, and a decline in glutamine de novo synthesis (from 156 +/- 15 to 93 +/- 13 mumol.kg-1.h-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Use of [13C]bicarbonate infusion for measurement of CO2 production.

To determine whether infusion of 13C-labeled bicarbonate can be used to measure rates of CO2 production (VCO2), seven healthy adults received 6-h primed continuous intravenous infusions of NaH13CO3 and L-[1-14C]leucine in the post-absorptive state while VCO2 was measured by indirect calorimetry. Indirect calorimetry and the use of specific activity and rate of 14CO2 expired yielded identical values of VCO2: 8.97 +/- 0.82 and 8.80 +/- 0.83 mmol/min, respectively (P = NS). The concentration of NaH13CO3 in the infusates and the 13C enrichment in breath CO2 were determined using gas chromatography-isotope ratio mass spectrometry. The rate of appearance of CO2 measured using the NaH13CO3 infusion rate and the steady-state breath 13CO2 enrichments was 11.41 +/- 1.56 mmol/min, which was higher (P < 0.001) than that determined by either of the other two methods. When corrected for the recovery of labeled CO2 during the infusion of NaH13CO3 by use of published values, rate of appearance of CO2 was 9.24 +/- 0.78 mmol/min, which did not differ from VCO2 determined using the other two methods. We conclude that infusion of NaH13CO3 can be used to determine VCO2. This method should be useful to study the oxidation of substrates in populations such as ventilator-dependent neonates, in whom indirect calorimetry is laborious and inaccurate.

Intercellular C-signaling and the traveling waves of Myxococcus.

Early in their development into fruiting bodies, Myxococcus xanthus cells organize themselves into dense bands that move as trains of traveling waves. C-factor, a 20-kD cell-surface bound protein, is a short-range developmental signal molecule required for these waves. What is the role of C-factor in the wave pattern? It is proposed that oriented collisions between cells initiate C-signaling, which, in turn, causes individual cells to reverse their direction of gliding. Cells would move about one wavelength and then reverse. Several lines of experimental evidence support these proposals: (1) Cells that suffered a mutation in the signal transduction pathway that controls the spontaneous reversal frequency lost the ability to form waves; (2) presentation of developing cells with detergent-solubilized C-factor increased the mean frequency of single cell reversal by three-fold; and (3) fluorescently labeled cells in the waves were tracked, and it was found that they moved and reversed on linear paths along the axis of wave propagation. Similar numbers of cells were found moving in the direction of ripple propagation, and in the reverse direction, as expected. (4) Dilution of C-signaling-competent cells with C-factor-deficient cells increased the wavelength as the probability of productive collision decreased. The waves exemplify a way that a multicellular pattern of stripes can be produced de novo, one that maintains a uniform 50-microns separation between stripes over a distance as large as 1 cm.

Spatial restriction of cellular differentiation.

Myxococcus xanthus cells differentiate into myxospores within a fruiting body, an aggregate of approximately 10(5) cells. Previous work had discerned an inner and outer domain within the fruiting body differentiated by cell density and cell alignment. To test whether the two domains might play different roles in spore differentiation, developmentally regulated gene fusions were screened for expression restricted to one domain or the other. Transcriptional lacZ fusions to 80 developmentally regulated genes were examined and eight fusions were found that restricted expression to the inner domain, while one fusion, omega 7621, showed initial expression in the outer domain. Initial omega 7621 expression coincided with patches of spore precursors evident in bright-field microscopy. Later in development, both omega 7621 expression and the patches expanded inward, eventually filling both the inner and outer domains. Previous work had also shown that high cell density and cell alignment are required for transmission of the C-signal, which is needed to initiate spore differentiation. Evidence is presented for a novel morphogenetic mechanism in which C-signaling in the outer (high density) domain initiates spore differentiation. It is proposed that spore precursors are passively transported from the outer to the inner domain by the movements of undifferentiated rod cells. Reconstruction experiments showed that developing rod cells move with sufficient force to displace spores. Spore precursors thus accumulate in the inner domain where they express spore-specific genes at high levels and account for inner domain specific expression.

Beta-galactosidase activity in single differentiating bacterial cells.

Myxococcus xanthus strains containing transcriptional fusions to lacZ were analyzed and fractionated by differences in their levels of beta-galactosidase expression. The fluorogenic substrate for beta-galactosidase, fluorescein di-beta-galactopyranoside, was introduced into M. xanthus cells during a rapid decrease in osmolarity of the medium followed by a return to isoosmolarity. Fluorescein, the product of hydrolysis, was retained within the cells and their viability was preserved. Fluorescence increased linearly with time and was proportional to beta-galactosidase activity. beta-Galactosidase expression in most fusion strains, though beginning at different phases of growth or development, was distributed unimodally amongst cells. However, fusion strain Tn5 lac omega 4473 was shown to be heterogeneous at 9 hr of development. It was possible to separate physically cells that expressed beta-galactosidase at a high level from other, still viable, cells with no expression. The approach described here could be adapted to study differentiation in plants and animals as well, where transcriptional fusions and fluorogenic substrates for enzyme probes of gene expression also can be used.

Two cell-density domains within the Myxococcus xanthus fruiting body.

Myxococcus xanthus, one of the simplest of multicellular organisms, develops into an organized, multicellular aggregate, called a fruiting body. Examination of the internal structure of the nascent fruiting body showed it to consist of a hemispherical outer domain of densely packed and ordered cells. Inside this dense shell is an inner domain of less ordered cells at 3-fold lower cell density. Single cells move in a bidirectional stream in the outer domain, orbiting the fruiting body throughout development, whereas in the inner domain, cell movement ceases as the fruiting body matures. The fruiting body thus consists of two domains, distinguished from each other by differential cell density, cell arrangements, and cell movements.

Use of a computer to assay motility in bacteria.

An assay was developed to study the movement of free-swimming Escherichia coli. Cells were videotaped through a microscope, and the videotape images were then digitized and analyzed with a computer. Angular and linear speeds were measured for wild-type E. coli and for a smooth and a tumbly mutant. The average angular and linear speeds of a population were directly and inversely proportional, respectively, to the time spent tumbling. Changes in angular and linear speeds were followed during the response of wild-type E. coli to attractant or repellent.