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Growth and survival of streptomycete inoculants and extent of plasmid transfer in sterile and nonsterile soil.

The growth and survival of strains of Streptomyces lividans and S. violaceolatus in sterile and nonsterile soil was investigated by using inoculated soil microcosms run as batch systems. It was evident that, after an initial short mycelial growth phase of 2 to 3 days, sporulation occurred and inoculants survived as spores. The transfer of a high-copy-number, self-transmissible plasmid, pIJ673, was detected by using intra- and interspecific crosses. The initial detection of transconjugants correlated with the development of the mycelial state of the inoculants (as confirmed by scanning electron microscopy) after 2 days of incubation. Subsequent spread of the plasmid was attributed to spread within existing mycelium followed by sporulation. In natural soil, inoculant numbers remained constant or declined, but plasmid transfer was readily detected.

Journal Article↗

Racial variation in retinopathy of prematurity. The Cryotherapy for Retinopathy of Prematurity Cooperative Group.

OBJECTIVES: To determine and compare the incidence of severe, vision-threatening retinopathy of prematurity (ROP) in black and white low-birth-weight infants. DESIGN: Prospective cohort study. SETTING: Seventy neonatal intensive care units in 23 US participating centers in the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity. PATIENTS: A total of 4099 premature infants weighing less than 1251 g at birth were enrolled to evaluate the natural history of ROP. This 'Natural History' cohort included 2158 white infants and 1584 black infants who were followed up prospectively according to a Natural History protocol. MAIN OUTCOME MEASURES: Incidence and severity of acute ROP. RESULTS: While ROP occurred with similar frequency in all racial subgroups, severe ROP was less common in black infants. One hundred sixty (7.4%) of 2158 white infants reached threshold ROP (defined as at least 5 contiguous or 8 cumulative clock-hours of stage 3 retinopathy in zone 1 or zone 2 in the presence of "plus disease" [dilation and tortuosity of the posterior pole blood vessels]), but only 51 (3.2%) of 1584 black infants progressed to threshold ROP. Using multiple logistic regression analysis, race emerged as a highly significant factor (P < .001) in the development of threshold disease, even when birth weight, gestational age status at delivery, sex, multiple births, and transport status were considered. CONCLUSIONS: Severe, vision-threatening ROP occurs with greater frequency in low-birth-weight white infants than in low-birth-weight black infants who are seemingly at equivalent risk. The reason for this disparity is unknown. We speculate that differences in retinal pigmentation may confer relative protection against free radical-mediated phototoxic injury in black infants.

Birth Weight↗

Quantum mechanical interpretation of nitrite reduction by cytochrome cd1 nitrite reductase from Paracoccus pantotrophus.

The reduction of nitrite to nitric oxide in respiratory denitrification is catalyzed by a cytochrome cd(1) nitrite reductase in Paracoccus pantotrophus (formerly known as Thiosphaera pantotropha LMD 92.63). High-resolution structures are available for the fully oxidized [Fülöp, V., Moir, J. W., Ferguson, S. J., and Hajdu, J. (1995) Cell 81, 369-377; Baker, S. C., Saunders, N. F., Willis, A. C., Ferguson, S. J., Hajdu, J., and Fülöp, V. (1997) J. Mol. Biol. 269, 440-455] and fully reduced forms of this enzyme, as well as for various intermediates in its catalytic cycle [Williams, P. A., Fülöp, V., Garman, E. F., Saunders, N. F., Ferguson, S. J., and Hajdu, J. (1997) Nature 389, 406-412]. On the basis of these structures, quantum mechanical techniques (QM), including density functional methods (DFT), were combined with simulated annealing (SA) and molecular mechanics techniques (MM) to calculate the electronic distribution of molecular orbitals in the active site during catalysis. The results show likely trajectories for electrons, protons, substrates, and products in the process of nitrite reduction, and offer an interpretation of the reaction mechanism. The calculations indicate that the redox state of the d(1) heme and charges on two histidines in the active site orchestrate catalysis locally. Binding of nitrite to the reduced iron is followed by proton transfer from His345 and His388 to one of the oxygens of nitrite, creating a water molecule and an [Fe(II)-NO(+)] complex. Valence isomerization within this complex gives [Fe(III)-NO]. The release of NO from the ferric iron is influenced by the protonation state of His345 and His388, and by the orientation of NO on the d(1) heme. Return of Tyr25 to a hydrogen-bonding position between His345 and His388 facilitates product release, but a rebinding of Tyr25 to the oxidized iron may be bypassed in steady-state catalysis.

Binding Sites↗

Effects of nativity, age at migration, and acculturation on smoking among adult Houston residents of Mexican descent.

OBJECTIVES: We investigated differences in smoking behaviors between US-and Mexican-born ever smokers and examined the influence of US culture on smoking initiation. METHODS: Participants were 5030 adults of Mexican descent enrolled in an ongoing population-based cohort in Houston, Tex. RESULTS: More men than women reported current smoking; rates among US-born women were higher than those among Mexican-born women. Smoking rates among US-born men were higher than earlier published rates among Hispanics and non-Hispanic Whites but similar to rates among African Americans. Current smoking rates among Mexican-born women were lower than published rates for Hispanics, non-Hispanic Whites, and African Americans. Older age, male gender, a higher level of acculturation, more than a high school education, and residing in a census tract with a higher median age predicted history of smoking among US-born participants. Among Mexican-born participants, older age, male gender, a higher level of acculturation, and younger age at migration predicted history of smoking. CONCLUSIONS: Smoking interventions for people of Mexican descent should be tailored according to gender, nativity, and acculturation level and should target all ages, not just young people.

Acculturation↗

Concordance between ICD-10 alcohol and drug use disorder criteria and diagnoses as measured by the AUDADIS-ADR, CIDI and SCAN: results of a cross-national study.

Agreement between the AUDADIS-ADR, CIDI and SCAN in case identification for ICD-10 alcohol and drug use disorders and diagnostic criteria was investigated in three countries, Luxembourg, Greece and the US. Overall, agreement for ICD-10 dependence diagnoses between the three instruments was fair to good for alcohol, opioids and cocaine, but generally lower for dependence diagnoses for other substance. In contrast, concordance between instruments for harmful use diagnoses was extremely poor for all substances. Implications of these major findings are discussed in terms of the relationship between prevalence, reliability and concordance and indications and cautions regarding cross-instrument comparisons.

Adult↗

Ventilatory responses to inhaled carbon dioxide at rest and during exercise in man.

1. Rapid steady-state CO2 responses were determined in six normal subjects at rest and five subjects at four different work loads up to 125 W, by injecting pure CO2 at constant flow into a small mixing chamber in the inspiratory limb of a breathing circuit. 2. The time course of the response of ventilation (V) and mean alveolar PCO2 (PACO2) was checked in separate experiments, where the flow rate of injected CO2 was changed abruptly and the effects were followed for 10 min. 3. V and PACO2 were measured every breath, and the results ensemble-averaged for each subject (two or three runs per subject) and then for the groups as a whole, in 30 s or 60 s time bins. 4. PACO2 during exercise was estimated by graphical reconstruction from the sloping alveolar plateau, and separately by the empirical equation of Jones, Robertson & Kane [1]. At rest, PACO2 was assumed equal to end-tidal PCO2 (PetCO2). 5. With the constant inflow technique, 4 min was required to reach steady-state V and PACO2 during exercise, and 6 min at rest. 6. At rest, with 4 min steps (doubtful steady state) the averaged CO2 response was concave up. With 6 min steps the response was almost linear. In neither case was the deviation from linearity statistically significant. 7. During exercise, the averaged CO2 responses were essentially isocapnic at work loads greater than 75 W with either method of deriving PACO2.

Adult↗

Behaviour of Dictyostelium discoideum amoebae and Escherichia coli grown together in chemostat culture.

When Dictyostelium discoideum amoebae and Escherichia coli were grown together in chemostat culture damped oscillations in the population densities of the organisms occurred followed by a sudden increase in bacterial numbers and a concommitant decrease in the number of amoebae. After the system had come to equilibrium altering the dilution rate resulted in a monotonic change in the experimental variables to new steady state levels. A square wave increase in the concentration of limiting nutrient in the feed medium during the oscillatory phase of culture produced a sinusoidal response indistinguishable from that prior to the perturbation. The results are more complicated than those predicted by simple models of microbial predator-prey dynamics although they correspond most nearly to models which incorporate saturation kinetics.

Animals↗

Hydrodynamics of polar liquid crystals.

Starting from a microscopic definition of an alignment vector proportional to the polarization, we discuss the hydrodynamics of polar liquid crystals with local C infinity v symmetry. The free energy for polar liquid crystals differs from that of nematic liquid crystals (D infinity h) in that it contains terms violating the n --> -n symmetry. First we show that these Z2-odd terms induce a general splay instability of a uniform polarized state in a range of parameters. Next we use the general Poisson-bracket formalism to derive the hydrodynamic equations of the system in the polarized state. The structure of the linear hydrodynamic modes confirms the existence of the splay instability.

Journal Article↗

Acute pancreatitis after EUS-guided FNA of solid pancreatic masses: a pooled analysis from EUS centers in the United States.

BACKGROUND: The aim of this study was to determine the frequency and the severity of pancreatitis after EUS-guided FNA of solid pancreatic masses. A survey of centers that offer training in EUS in the United States was conducted. METHODS: A list of centers in which training in EUS is offered was obtained from the Web site of the American Society for Gastrointestinal Endoscopy. Designated program directors were contacted via e-mail. The information requested included the number of EUS-guided FNA procedures performed for solid pancreatic masses, the number of cases of post-procedure pancreatitis, and the method for tracking complications. For each episode of pancreatitis, technical details were obtained about the procedure, including the location of the mass, the type of fine needle used, the number of needle passes, and the nature of the lesion. RESULTS: Nineteen of the 27 programs contacted returned the questionnaire (70%). In total, 4909 EUS-guided FNAs of solid pancreatic masses were performed in these 19 centers over a mean of 4 years (range 11 months to 9 years). Pancreatitis occurred after 14 (0.29%): 95% CI[0.16, 0.48] procedures. At two centers in which data on complications were prospectively collected, the frequency of acute pancreatitis was 0.64%, suggesting that the frequency of pancreatitis in the retrospective cohort (0.26%) was under-reported (p=0.22). The odds that cases of pancreatitis would be reported were 2.45 greater for the prospective compared with the retrospective cohort (95% CI[0.55, 10.98]). The median duration of hospitalization for treatment of pancreatitis was 3 days (range 1-21 days). The pancreatitis was classified as mild in 10 cases, moderate in 3, and severe in one; one death (proximate cause, pulmonary embolism) occurred after the development of pancreatitis in a patient with multiple comorbid conditions. CONCLUSIONS: EUS-guided FNA of solid pancreatic masses is infrequently associated with acute pancreatitis. The procedure appears to be safe when performed by experienced endosonographers. The frequency of post EUS-guided FNA pancreatitis may be underestimated by retrospective analysis.

Acute Disease↗

31P NMR studies of the metabolic status of pig hearts preserved for transplantation.

31P NMR spectroscopy has been used to evaluate the metabolic status of cardioplegically arrested pig hearts. Hearts were stored with Plegisol for up to 12 hours at either 5 degrees C or 12 degrees C. Results indicated that the ATP content of hearts could be maintained (greater than 70% of initial values) for up to 5 hours in the ischemic storage state. The ATP loss was greater at 12 degrees C. PCr was lost exponentially under the same conditions. Functional testing by reperfusing the stored hearts in vitro indicated a good correlation between the ATP content and survivability of the preparations. Twenty-four hour preservation of pig hearts using slow perfusion with a modified cardioplegic solution (Wicomb) allowed for preservation of both PCr and ATP, in all cases, reperfusion of hearts revealed a loss of NMR- visible ATP and PCr.

Adenosine Triphosphate↗

Prospective study of the value of necropsy examination in early death after cardiac surgery.

OBJECTIVE: To assess the value of necropsy examination in patients dying soon after cardiac surgery, particularly the proportion of clinical questions answered by the necropsy, the frequency of major unexpected findings, and the limitations of the procedure. DESIGN: A three year prospective study of necropsy examinations in adult patients dying before discharge or within 30 days of cardiac surgery performed under cardiopulmonary bypass in one hospital. SETTING: Tertiary referral centre. RESULTS: 123 of 2781 patients (4.4%) died in the early postoperative period, and necropsy examination was performed in 108 of these (88%). The mortality after emergency procedures (18%) was much higher than after routine operations (2.6%). The main causes of death were cardiac failure (52%), haemorrhage (14%), cerebral disease (6%), and pulmonary emboli (5%). The necropsy changed the stated cause of death in 16 patients (15%), and answered clinical questions in 24 of 38 patients. In 15 patients necropsy examination did not provide a full explanation of death. Most of these patients died of cardiac failure soon after surgery or were sudden unexpected deaths. CONCLUSIONS: Necropsy examination in patients dying early after cardiac surgery is valuable as it answers the majority of clinical questions, and shows unexpected findings in a significant proportion of cases.

Adult↗

The relationship between dorsolateral prefrontal N-acetylaspartate measures and striatal dopamine activity in schizophrenia.

BACKGROUND: Pathology of dorsolateral prefrontal cortex and dysregulation of dopaminergic neurons have been associated with the pathophysiology of schizophrenia, but how these phenomena relate to each other in patients has not been known. It has been hypothesized that prefrontal cortical pathology might induce both diminished steady-state and exaggerated responses of dopaminergic neurons to certain stimuli (e.g., stress). We examined the relationship between a measure of prefrontal neuronal pathology and striatal dopamine activity in patients with schizophrenia and in a nonhuman primate model of abnormal prefrontal cortical development. METHODS: In the patients, we studied in vivo markers of cortical neuronal pathology with NMR spectroscopic imaging and of steady-state striatal dopamine activity with radioreceptor imaging. In the monkeys, we used the same NMR technique and in vivo microdialysis. RESULTS: Measures of N-acetyl-aspartate concentrations (NAA) in dorsolateral prefrontal cortex strongly and selectively predicted D2 receptor availability in the striatum (n = 14, rho = -.64, p < .01), suggesting that the greater the apparent dorsolateral prefrontal cortex pathology, the less the steady-state dopamine activity in these patients. A similar relationship between NAA measures in dorsolateral prefrontal cortex and steady-state dopamine concentrations in the striatum was found in the monkeys (n = 5, rho = .70, p < .05). We then tested in the same monkeys the relationship of prefrontal NAA and striatal dopamine overflow following amphetamine infusion into dorsolateral prefrontal cortex. Under these conditions, the relationship was inverted, i.e., the greater the apparent dorsolateral prefrontal cortex pathology, the greater the dopamine release. CONCLUSIONS: These data demonstrate direct relationships between putative neuronal pathology in dorsolateral prefrontal cortex and striatal dopamine activity in human and nonhuman primates and implicate a mechanism for dopamine dysregulation in schizophrenia.

Adult↗

Refractive errors in young children with Down syndrome.

Significant refractive errors are common among older children and adults with Down syndrome. We examined infants and children with Down syndrome to determine the prevalence of these errors at younger ages. Noncycloplegic retinoscopy was used to determine the refractive state of 92 infants and children with Down syndrome, aged 4 months to 12 years. The results for infants show a similar distribution of refractive errors in patients with Down syndrome and an age-matched control group. However, rather than a narrower distribution for the older age groups, as is the case with the controls, the distribution is wider, and the prevalence of refractive errors (including astigmatism) is higher among young children with Down syndrome than among controls. This high prevalence of refractive defects cannot be explained by the presence of strabismus or other pathologies.

Child↗

Structural characterization of Paracoccus denitrificans cytochrome c peroxidase and assignment of the low and high potential heme sites.

The amino acid sequence of the diheme cytochrome c peroxidase from Paracoccus denitrificans has been determined as the result of sequence analysis of peptides generated by chemical and enzymatic cleavages of the apoprotein. The sequence shows 60% similarity to the cytochrome c peroxidase from Pseudomonas aeruginosa, 39% similarity to an open reading frame encoding a putative triheme c-type cytochrome in Escherichia coli, and remote similarity to the MauG proteins from two methylotrophic bacteria. It is proposed, on the basis of the pattern of conserved residues in the sequences, that a change in iron coordination in the N-terminal heme domain may accompany reduction to the active mixed valence state, a change which may be accompanied by conformational adjustments in the highly conserved interface between the N- and C-terminal domains. These conformational adjustments may also lead to the appearance of a second Ca2+ binding site in the mixed valence enzyme. The exposed edge of the heme in the C-terminal domain is surrounded by several different patterns of charged residues in the Paracoccus and Pseudomonas enzymes, and this is consistent with the interaction of the former with the highly positively charged front face of the donor cytochrome c-550.

Amino Acid Sequence↗

Hypertension in minorities: blacks.

Hypertension is known to occur much more frequently in blacks than in the general population, roughly 33% to 50% more frequently. In addition, severe hypertension occurs 3 to 7 times more commonly in blacks than whites and is associated with an excessive amount of target organ damage. Thus, damage to the heart, kidneys, and cerebral structures may occur as much as three to five times more frequently in blacks than the general population and is associated with a much greater mortality. Because of differences in clinical presentation, delays in entering the medical care system, and some pathophysiologic features specific for the black population, treatment becomes somewhat more challenging and should be tailored for this population. Because of economic factors often found in minority populations, inexpensive effective drugs such as diuretics and beta-blockers, which are preferred drugs according to the JNC-V, often should be given first consideration in this population. However, calcium channel blockers seem to be quite effective in this group, equal to in the white population, although they are somewhat more expensive. Angiotensin converting enzyme inhibitors, if given in proper dosage and especially with low dose diuretics, are also quite effective in this population. Tissue specific angiotensin converting enzyme inhibitors may be more effective, but further studies are needed. Studies have shown that effective treatment of the black population, in spite of the differences and the more challenging situation, can result in improved survival and reduction in morbidity and mortality from the various complications.

Black People↗

Prospective data on the prevalence of abnormal involuntary movements among elderly people living in the community.

Trained raters from the Liverpool Continuing Health in the Community study interviewed 1070 people over the age of 65 in 1982-1983 using the Geriatric Mental State (GMS) examination. Three years later the cohort was re-interviewed, this time by psychiatrists trained in the GMS, who used the GMS and the History and Aetiology Schedule (HAS). The cohort had fallen in size to 875, because of mortality; 701 were re-interviewed. The cohort was followed up again 6 years after the first interview by trained nurse raters using the GMS (A3) and the Mini-Mental State Examination. Cases of mental disorder identified by the computer diagnostic program AGECAT were re-interviewed by psychiatrists along with a number of controls using the GMS and the HAS on the remaining 450 individuals. Observational behavioural ratings from the GMS and summary sheets were analysed along with AGECAT diagnoses and data on medication gained at the 3 assessments. The community prevalence of tardive dyskinesia and other movement disorders in elderly people over a 6-year follow-up appears to be very low (the community prevalence of tardive dyskinesia being 0.22% and akathisia 1.57%), is usually associated with organic mental disorder (and consequently higher mortality) and is furthermore not usually associated with antipsychotic medication.

Aged↗

Effects of short-term glucocorticoids on cardiovascular biomarkers.

CONTEXT: Glucocorticoids are known to acutely increase blood pressure, suppress inflammation, and precipitate insulin resistance. However, the short-term effects of glucocorticoids on other cardiovascular risk factors remain incompletely characterized. OBJECTIVE: Our objective was to determine the effects of a short course of dexamethasone on multiple cardiovascular biomarkers and to determine whether suppression of morning cortisol in response to low-dose dexamethasone is correlated with cardiovascular risk markers in healthy volunteers. DESIGN: We conducted a randomized, double-blind, placebo-controlled study. SETTING: The study took place in a tertiary care hospital. STUDY SUBJECTS: Twenty-five healthy male volunteers, ages 19-39 yr, participated in the study. INTERVENTION: Subjects received either 3 mg dexamethasone twice daily or placebo for 5 d. Subjects also underwent a low-dose (0.5 mg) overnight dexamethasone suppression test. MEASURES: Parameters examined before and after the 5-d intervention included heart rate, blood pressure, weight, fasting lipid variables, homocysteine, renin, aldosterone, insulin resistance (homeostasis model assessment), high-sensitivity C-reactive protein, B-type natriuretic peptide, flow-mediated and nitroglycerin-mediated brachial artery dilatation, and heart rate recovery after exercise. All measurements were done in the morning hours in the fasting state. RESULTS: Dexamethasone increased systolic blood pressure, weight, B-type natriuretic peptide, and high-density-lipoprotein-cholesterol. Dexamethasone decreased resting heart rate, high-sensitivity C-reactive protein, and aldosterone and tended to attenuate nitroglycerin-mediated vasodilatation. There was no effect on flow-mediated vasodilatation, diastolic blood pressure, triglycerides, low-density-lipoprotein-cholesterol, nonesterified fatty acids, homocysteine, or heart rate recovery. The response of circulating cortisol to low-dose dexamethasone had no significant correlation with any of the cardiovascular risk markers. CONCLUSIONS: Short-term glucocorticoids elicits both favorable and unfavorable effects on different cardiovascular risk factors. Manipulation of specific glucocorticoid-responsive physiological pathways deserves further study.

Adult↗

Blood pressure as a risk factor for depression in elderly people: a prospective study.

A total of 1070 men and women aged 65 years and over living in the community in Liverpool were interviewed using the Geriatric Mental State. Diagnoses of depression at case and subcase level were made using the GMS-AGECAT package from an initial interview and at follow-up three years later. Data relating to blood pressure at year 0 was available on 748 subjects. Men not taking anti-hypertensives or antidepressants with diastolic blood pressure greater than 85 mmHg were significantly less likely to be subcases than men with low or normal diastolic pressure. People in this group were also significantly less likely to be cases 3 years later. There were no other significant findings. These results do not support an association between low blood pressure and coincidental or future subcase- or case-level depressive illness.

Aged↗