Comparison of bacterial counts in expressed breast milk following standard or strict infection control regimens in neonatal intensive care units: compliance of mothers does matter.

Bacterial counts in 1466 expressed breast milk (EBM) samples from women following one of two infection control regimens (standard vs strict) were investigated. Overall, 12% of samples yielded Gram-negative bacteria, with no significant differences between the standard [11.9% (94/788)] and strict [12.1% (82/678)] regimens (P = 0.92). Significantly more samples were contaminated when expressed at home (standard regimen home/hospital: 17.9% vs 6.1%; strict regimen home/hospital: 19.6% vs 3.4%; P < 0.001). Bacterial contamination of EBM was not associated with the regimen, but was associated with the location of breast milk expression. Attempts to improve personal hygiene during milk collection seem to be of limited value. Good hygiene of collection and storage equipment is likely to be the most important way to ensure the microbiological quality of EBM.

Pion electromagnetic form factor at spacelike momenta.

A novel method is employed to compute the pion electromagnetic form factor, F(π)(Q²), on the entire domain of spacelike momentum transfer using the Dyson-Schwinger equation (DSE) framework in QCD. The DSE architecture unifies this prediction with that of the pion's valence-quark parton distribution amplitude (PDA). Using this PDA, the leading-order, leading-twist perturbative QCD result for Q²F(π)(Q²) underestimates the full computation by just 15% on Q²â‰³8 GeV², in stark contrast to the result obtained using the asymptotic PDA. The analysis shows that hard contributions to the pion form factor dominate for Q²â‰³8 GeV², but, even so, the magnitude of Q²F(π)(Q²) reflects the scale of dynamical chiral symmetry breaking, a pivotal emergent phenomenon in the standard model.

Pion distribution amplitude from lattice QCD.

A method is explained through which a pointwise accurate approximation to the pion's valence-quark distribution amplitude (PDA) may be obtained from a limited number of moments. In connection with the single nontrivial moment accessible in contemporary simulations of lattice-regularized QCD, the method yields a PDA that is a broad concave function whose pointwise form agrees with that predicted by Dyson-Schwinger equation analyses of the pion. Under leading-order evolution, the PDA remains broad to energy scales in excess of 100 GeV, a feature which signals persistence of the influence of dynamical chiral symmetry breaking. Consequently, the asymptotic distribution φπ(asy)(x) is a poor approximation to the pion's PDA at all such scales that are either currently accessible or foreseeable in experiments on pion elastic and transition form factors. Thus, related expectations based on φ φπ(asy)(x) should be revised.

Imaging dynamical chiral-symmetry breaking: pion wave function on the light front.

We project onto the light front the pion's Poincaré-covariant Bethe-Salpeter wave function obtained using two different approximations to the kernels of quantum chromodynamics' Dyson-Schwinger equations. At an hadronic scale, both computed results are concave and significantly broader than the asymptotic distribution amplitude, φ(π)(asy)(x)=6x(1-x); e.g., the integral of φ(π)(x)/φ(π)(asy)(x) is 1.8 using the simplest kernel and 1.5 with the more sophisticated kernel. Independent of the kernels, the emergent phenomenon of dynamical chiral-symmetry breaking is responsible for hardening the amplitude.

Gustatory and reward brain circuits in the control of food intake.

Gustation is a multisensory process allowing for the selection of nutrients and the rejection of irritating and/or toxic compounds. Since obesity is a highly prevalent condition that is critically dependent on food intake and energy expenditure, a deeper understanding of gustatory processing is an important objective in biomedical research. Recent findings have provided evidence that central gustatory processes are distributed across several cortical and subcortical brain areas. Furthermore, these gustatory sensory circuits are closely related to the circuits that process reward. Here, we present an overview of the activation and connectivity between central gustatory and reward areas. Moreover, and given the limitations in number and effectiveness of treatments currently available for overweight patients, we discuss the possibility of modulating neuronal activity in these circuits as an alternative in the treatment of obesity.

Pair production and optical lasers.

Electron-positron pair creation in a standing wave is explored using a parameter-free quantum kinetic equation. Field strengths and frequencies corresponding to modern optical lasers induce a material polarization of the QED vacuum, which may be characterized as a plasma of e+e- quasiparticle pairs with a density of approximately 10(20) cm-3. The plasma vanishes almost completely when the laser field is zero, leaving a very small residual pair density n(r) which is the true manifestation of vacuum decay. The average pair density per period is proportional to the laser intensity but independent of the frequency nu. The density of residual pairs also grows with laser intensity but n(r) proportional to nu(2). With optical lasers at the forefront of the current generation, these dynamical QED vacuum effects can plausibly generate 5-10 observable two-photon annihilation events per laser pulse.

Quantum effects with an x-ray free-electron laser.

A quantum kinetic equation coupled with Maxwell's equation is used to estimate the laser power required at an x-ray free-electron laser (XFEL) facility to expose intrinsically quantum effects in the process of QED vacuum decay via spontaneous pair production. A 9 -TW-peak XFEL laser with photon energy of 8.3 keV could be sufficient to initiate particle accumulation and the consequent formation of a plasma of spontaneously produced pairs. The evolution of the particle number in the plasma will exhibit non-Markovian aspects of the strong-field pair production process, and the plasma's internal currents will generate an electric field whose interference with that of the laser leads to plasma oscillations.

Pair creation and an x-ray free electron laser.

Using a quantum kinetic equation we study the possibility that focused beams at proposed x-ray free electron laser facilities can initiate spontaneous electron-positron pair production from the QED vacuum. Under conditions reckoned achievable at planned facilities, repeated cycles of particle creation and annihilation will take place in tune with the laser frequency. The peak particle number density is insensitive to this frequency, and one can anticipate the production of a few hundred particle pairs per laser period.

Management of lawnmower injuries to the lower extremity in children and adolescents.

Lawnmower-associated trauma remains a substantial source of extremity injury in the pediatric and adolescent patient populations, producing complex wounds that require a combined orthopedic and plastic surgical approach. The authors review their experience with 16 patients, 2 to 17 years of age (mean age, 6.2 years), who were admitted to Duke University Medical Center for lower extremity lawnmower trauma between January 1988 and December 1999. The average hospitalization time was 13.5 days, and an average of 2.9 surgical procedures per patient were performed. Early debridement and bony fixation were carried out in all patients; 8 patients sustained traumatic amputations. Fifteen of 20 nonamputation fractures involved the foot and were managed with either closed reduction or K-wire fixation. Three of five long-bone fractures underwent external fixation. Wound closure was achieved with direct closure or skin grafting in the majority of patients. However, five microsurgical free flap transfers were required for extensive defect reconstruction of the foot (N = 4) and knee (N = 1). Adequate immediate debridement, fracture reduction, and early primary or if necessary secondary wound coverage including microsurgical free tissue transfer to prevent further damage and long-term disability in these type of devastating injuries is recommended.

Wound management products--the evidence we need and the difficulties in obtaining it.

The management of complex wounds requires the expertise and co-ordinated effort of multiple disciplines in a variety of healthcare settings. Providers of wound care will be held increasingly responsible for the impact of clinical and economic outcomes for the patient, healthcare system and, ultimately, society as a whole. Collecting and analysing outcome data and comparing it to regional and national standards, will be the method which demonstrates the quality of service provided. This paper will review the design implications for conducting comparisons of therapies used in the management of wounds. Consideration will be given to overall design, sample size calculations, clinical setting, choice of comparator and mechanisms for exploring how efficacy and cost data can be linked. Evidence obtained from several prospective randomised clinical trials will be used as examples to support the theoretical considerations.

Data quality of the Drug Abuse Warning Network.

The purpose of this article was to assess the quality of data collected by the Drug Abuse Warning Network (DAWN), which reports drug abuse emergency department visits. The results of quality assurance studies at 36 sites were reviewed and interpreted. Data collection procedures are not consistent among hospitals and, along with personnel, regularly change within a hospital. Trained investigators reabstracted DAWN report forms at 24 sites and determined that only 57.4% of the cases that met DAWN case definition criteria had been reported; one of five cases had been reported at one site. The technique used in 11 (47.8%) of 23 hospitals to screen for potential DAWN cases detected only 36% of the cases found when all medical charts are examined. The investigators found discrepancies between reported and actual cases in 81.3% of the report forms reabstracted, with an average of 2.3 errors per form. Information as to the drug(s) involved was incorrect in 36.3% of the forms. Due to underreporting of drug abuse emergency department visits and poor quality data in DAWN report forms, DAWN estimates of drug activity must be viewed with caution. Furthermore, estimation of trends is risky, due to differences between emergency departments as to reporting systems and changes over time.

The effects of non-nutritional factors on growth in cerebral palsy.

This study was designed to evaluate the effects of non-nutritional factors alone on the growth of children with cerebral palsy (CP). 20 children with hemiplegic CP, normal stature and normal triceps skinfold measurements had 16 different anthropometric measures performed on each side of the body (affected vs unaffected). All measures of breadth, circumference and length were significantly smaller on the affected side compared with the unaffected side. Skinfold measurements had a tendency to be larger on the affected side. These results suggest that non-nutritional factors related to disease severity have a significant influence on the growth of children with CP, even in the absence of malnutrition.

Structure-activity relationships of C1 and C6 side chains of zaragozic acid A derivatives.

Systematic modification of the C6 acyl side chain of zaragozic acid A, a potent squalene synthase inhibitor, was undertaken to improve its biological activity. Simplification of the C6 side chain to the octanoyl ester has deleterious effects; increasing the linear chain length improves the in vitro activity up to the tetradecanoyl ester. An omega-phenoxy group is a better activity enhancer than an omega-phenyl group. A number of C6 carbamates, ethers, and carbonates were prepared and found to have similar activity profiles as the C6 esters. In the preparation of C6 ethers, C4 and C4,6 bisethers were also isolated; their relative activity is: C6 > C4 > C4,6. These C6 long-chain derivatives are subnanomolar squalene synthase inhibitors; they are, however, only weakly active in inhibiting hepatic cholesterol synthesis in mice. The C6 short-chain derivatives are much less active in vitro, but they all have improved oral activity in mice. Modification of the C1 alkyl side chain of the n-butanoyl analogue (ED50 4.5 mg/kg) did not improve the po activity further. A number of these C6 long-chain derivatives are also potent antifungal agents in vitro.

Evaluation of a hydrocellular dressing in the management of exuding wounds in the community.

A multicentre clinical trial was conducted to assess the performance and acceptability of a hydrocellular dressing in the management of exuding wounds by community nurses. The study examined ease of use, adherence, patient comfort, conformability and safety in use. Since this article was written, Allevyn hydrocellular dressing has become available on the Drug Tariff.

Effect of hemiplegia on skeletal maturation.

Children with cerebral palsy have been reported to have poor growth and delayed skeletal maturation, but it is unclear whether these effects are related to the underlying brain injury or to concomitant malnutrition. This study was designed to evaluate the effects of hemiplegic cerebral palsy on skeletal maturation and growth, with the unaffected side used as each subject's control. Bilateral hand-wrist radiographs were obtained for 19 children with spastic hemiplegia. Skeletal maturation was determined in a blinded fashion with the Fels method. The skeletal age of the affected (hemiplegic) side was less than that of the unaffected (control) side in all 19 subjects; the mean difference in skeletal age was 7.3 months (p < 0.001). The delay in skeletal maturation of the affected side correlated linearly with age and upper extremity function. These findings show that brain injury results in delayed skeletal maturation independent of malnutrition. This effect on skeletal maturation may explain, in part, the reason that some children with cerebral palsy grow poorly.

Dose-response relationship in skin sensitization.

The dose-response relationship (challenge phase) of the skin sensitization response was investigated in previously sensitized Hartley guinea pigs. Larger numbers of animals were used per group at the lower doses so that statistically significant observations could be made. Model compounds known to be skin sensitizers were used: a strong sensitizer, dinitrochlorobenzene (DNCB), and a weaker sensitizer, p-phenylenediamine (PPDA). A gradation in response to changing DNCB doses was easily observed by using either the open epicutaneous test (OET) or the Buehler occlusive patch test. The Buehler test was used to study the dose-response relationship of DNCB sensitization. The sensitivity of the OET and Buehler test was judged not adequate to measure the dose response for PPDA, because at high doses a high incidence of responders was not obtained. Therefore, the maximization test was used to evaluate PPDA. Similar, non-linear dose-response curves were obtained with each compound. The higher doses produced a somewhat linear relationship, but at lower doses the curves flattened out and more slowly approached a zero response. Thus, for potent sensitizers, concentrations found in exposure situations might be in the linear portion of the dose-response curve. For weak responders, use concentrations might be in the shallow portion of the curve, where reactions would be underestimated if a linear dose-response curve were assumed.

gamma-Aminobutyric acid-opioid interactions in the regulation of gonadotropin secretion in the immature female rat.

Previous studies in the male rat have demonstrated that GABA acting via GABAB receptors can abolish naloxone-induced LH secretion. The purpose of the present study was to determine if an analogous situation exists in the female rat. Naloxone administered to ovariectomized immature rats had no effect on LH release. In contrast, naloxone potently stimulated LH release in estrogen-primed ovariectomized immature rats. Elevation of endogenous brain levels of GABA by administering amino-oxyacetic acid, an inhibitor of GABA catabolism, prevented the naloxone-stimulated release of LH. This effect appeared to be both GABAA and GABAB receptor mediated, since exogenous administration of either muscimol (GABAA agonist) or baclofen (GABAB agonist) prevented the naloxone-induced release of LH. Neither GABA agonist had any effect on LHRH-stimulated LH release in vivo, suggesting that their effect was specific and achieved at the level of the CNS. In contrast to its inhibitory effect on naloxone-stimulated LH and FSH release, muscimol increased basal LH and FSH release in vivo and from hemipituitaries incubated in vitro, while having no effect on LHRH release from mediobasal hypothalamic and preoptic area fragments in vitro. Thus, under conditions of basal LH release, activation of GABAA receptors in the anterior pituitary can actually lead to enhanced LH secretion. Finally, naloxone-stimulated LH release was found to be inhibited by the alpha 1- and alpha 2-adrenergic blockers, prazosin and yohimbine, suggesting that naloxone-stimulated LH release is mediated via catecholamine neurotransmission involving alpha 1- and alpha 2-adrenergic receptor activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Progesterone and corticosteroid regulation of hypothalamic and pituitary opioid content during LH surge induction.

The purpose of this study was to determine whether steroid hormones affect brain opioid content during the time of gonadotropin surge induction. Ovariectomized rats (26 days old) were primed with estradiol (E(2)) (2 mug) for 2 days. E(2) treatment markedly suppressed hypothalamic beta-endorphin content at 1500 h, 1800 h (Day 29), and 0800 h (Day 30) but had no effect on pituitary beta-endorphin levels. The administration of progesterone (P(4)) at 0900 h on Day 29 caused a luteinizing hormone (LH) and a follicle-stimulating hormone (FSH) surge at 1500 h that same day. Interestingly, hypothalamic beta-endorphin content was unchanged during the LH surge induced by P(4), although a nonsignificant elevation of hypothalamic beta-endorphin levels was noticed in P(4)-treated rats the morning after the surge. Triamcinolone acetonide (TA) treatment induced a large LH and FSH surge at 1500 h. Similar to P(4), TA did not alter hypothalamic beta-endorphin levels during the time of the LH surge; however, after the surge, TA-treated rats had a significant increase in hypothalamic beta-endorphin levels at 1800 h (Day 29) and 0800 h the next morning. Cortisol had no effect on LH levels but increased FSH levels at 0800 h on Day 30. Similar to TA, cortisol caused an elevation in hypothalamic beta-endorphin levels at 1800 h and 0800 h the next day. Finally, pituitary dynorphin A 1-13 content was not affected by any of the steroids. This study suggests that E(2) is principally responsible for reducing hypothalamic opioid content. The stimulatory effect of progesterone and TA on gonadotropin secretion appears to be due to the turning on of an excitatory signal rather than the turning off of an inhibitory opioid signal.

Statistical model in tests for eye irritants.

A test used to classify substances for eye irritancy, as required by the Consumer Product Safety Commission, is performed on 1-3 groups of 6 albino rabbits in a sequential manner. When the statistical implications of the test are realized, it is possible for a substance to be classified as an irritant with fewer reactions than the number required for it to be classified as not an irritant. A procedure is given for correcting the inconsistency in the current test, and an alternative test, which considerably reduces the number of animals required, is proposed. Probability models and expected sample size calculations have been derived.

Bacteriological quality control in human milk-banking.

The bacteriological quality of pooled human milk donated to the Oxford milk bank was analysed and the effects on bacteriology of sterilisation of the milk-collecting vessels in the home with hypochlorite solution and of Holder pasteurisation in a purpose-built human-milk pasteuriser were studied. Collecting milk in hypochlorite-sterilised vessels resulted in a significantly lower bacterial count of both pathogens and species of unlikely pathogenicity before pasteurisation and significantly increased the chance of pasteurisation giving a sterile product. Potentially pathogenic organisms grown in untreated milk were Escherichia coli, Staphylococcus aureus, and group B beta-haemolytic streptococci. Seven species of organisms of unlikely pathogenicity were also identified. Pasteurisation eliminated all potential pathogens from milk but did not reliably remove any of the species of unlikely pathogens. Banked human milk may be contaminated with bacteria which are known to be capable of producing lipases, proteases, and decarboxylases. Accurate pasteurisation, together with attention to the sterility of the collecting vessels, results in a bacteriologically safe product that retains many of the protective properties of raw milk.