Mean Sp Research Articles

Isotopomer signatures of soil-emitted N 2O under different moisture conditions—A microcosm study with arable loess soil

Soils represent the major source of the atmospheric greenhouse gas nitrous oxide (N 2O) and there is a need to better constrain the total global flux and the relative contribution of the microbial source processes. The aim of our study was to evaluate isotopomer analysis of N 2O (intramolecular distribution of 15N) as well as conventional nitrogen and oxygen isotope ratios (i) as a tool to identify N 2O production processes in soils and (ii) to constrain the isotopic fingerprint of soil-derived N 2O. We conducted a microcosm study with arable loess soil fertilized with 20 mg N kg −1 of 15NO 3 −-labeled or non-labeled ammonium nitrate. Soils were incubated for 16 d at varying moisture (55%, 75% and 85% water-filled pore space (WFPS)) in order to establish different levels of nitrification and denitrification. Dual isotope and isotopomer ratios of emitted N 2O were determined by mass spectrometric analysis of δ 18O, average δ 15N ( δ 15N bulk) and 15N site preference (SP=difference in δ 15N between the central and peripheral N-positions of the asymmetric N 2O molecule). Total rates and N 2O emission of denitrification and nitrification were determined by 15N analysis of headspace gases and soil extracts of the 15NO 3 − treatment. N 2O emission and denitrification increased with moisture whereas gross nitrification was almost constant. In the 55% WFPS treatment, more than half of the N 2O flux was derived from nitrification, whereas denitrification was the dominant N 2O source in the 75% WFPS and 85% WFPS treatments. Moisture conditions were reflected by the isotopic signatures since highly significant differences were observed for average δ 15N bulk, SP and δ 18O. Experiment means of the 75% WFPS and 85% WFPS treatments gave negative δ 15N bulk (−18.0‰ and −34.8‰, respectively) and positive SP (8.6‰ and 15.3‰, respectively), which we explained by the fractionation during N 2O production and partial reduction to N 2. In the 55% WFPS treatment, mean SP was relatively low (1.9‰), which suggests that nitrification produced N 2O with low or negative SP. The observed influence of process condition on isotopomer signatures suggests that the isotopomer approach might be suitable for identifying N 2O source processes. However, more research is needed to determine the impact from process rates and microbial community structure. Isotopomer signatures were within the range reported from previous soil studies which supports the assumption that SP of soil-derived N 2O is lower than SP of tropospheric N 2O.

Prevalence of oxygen desaturation and use of oxygen at home in adults at sea level and at moderate altitude

The aim of this study was to determine the prevalence of oxygen desaturation in adults aged>or=40 yrs as altitude above sea level increases. A population-based, cross-sectional study with a multistage cluster sampling of 1,063 subjects from metropolitan Mexico City (Mexico; 2,240 m above sea level), 1,357 from Caracas (Venezuela; 950 m) and 943 from Montevideo (Uruguay; 35 m). The mean of six measurements of arterial oxygen saturation (SP,O2) was estimated using a pulse oximeter. Mean SP,O2 decreased with altitude. No subject from Montevideo had a mean SP,O2<or=88%. Prevalence of subjects with SP,O2<or=88%, a common criterion used for oxygen prescription, was 1.0% in Caracas and 6.0% in Mexico City. Additional predicting factors for hypoxaemia in multiple regression models were age, body mass index and a low forced expiratory volume in one second as a percentage of the predicted value. In Mexico City and Caracas, <10% of the hypoxaemic subjects reported use of domiciliary oxygen, whereas at least half of the subjects reporting use of oxygen at home had a resting SP,O2>88%. In conclusion, the prevalence of hypoxaemia was closely related to altitude. Priorities for oxygen prescription must be defined in moderate altitudes because it is unfeasible to provide it to all subjects fulfilling the criteria commonly used.

VALId: VALIDATION OF PROTEIN SEQUENCE QUALITY BASED ON MULTIPLE ALIGNMENT DATA

The validation of sequences is essential to perform accurate phylogeny and structure/function analysis. However among the thousands of protein sequences available in the public databases, most have been predicted in silico and have not systematically undergone a quality verification. It has recently become evident that they often contain sequence errors. To address the problem of automatic protein quality control, we have developed vALId, an interactive web interfaced software. Taking advantage of high quality multiple alignments of complete protein sequences (MACS), vALId first warns about the presence of suspicious insertions, deletions (indels) and divergent segments, and second, proposes corrections based on transcripts and genome contigs. In a first evaluation test, hundreds of indels and divergent segments were randomly generated in a manually refined MACS. The sensitivity (Sn) and specificity (Sp) of indel detection were excellent (0.96) while the mean Sn(0.49) and Sp(0.56) of divergent segment delineation depended on the percent identity between sequence neighbors. In a second test, 6195 sequences in 100 MACS corresponding to different functional and structural protein families were analyzed. 65% of the sequences were in silico predictions and 44% of eukaryote predicted proteins were partially incorrect with at least one suspicious indel or divergent segment.

HEMO equilibrated Kt/V goals are difficult to achieve in large male patients.

The long-term outcome of chronic hemodialysis patients is influenced by the adequacy of dialysis treatment. A major objective of the ongoing US HEMO Study is to determine if a higher target value of treatment as measured by the equilibrated Kt/V (eKt/V), a calculation of dialysis adequacy developed for the study, of 1.45 results in a better outcome than the presently accepted target value for eKt/V of 1.05 (approximately equal to spKt/V of 1.2). eKt/V corrects for urea rebound and gives a better estimate of actual treatment received. To examine the feasibility of achieving the higher eKt/V in large hemodialysis patients, a retrospective analysis of 389 monthly eKt/V values from 65 men on chronic hemodialysis of larger than average size dialyzed at high blood and dialysate flows (QB 400, QD 800 ml/min) with large dialyzers (1.8-2.2 m2) for longer than 4 hours three times weekly was performed. A total of 278 treatments considered optimal by a blood water urea clearance estimate were included in the final analyses. The mean body weight and Chertow water volume were 84.3+/-16.5 kgm and 50.0+/-6.7 L, respectively. The mean sp Kt/V was 1.29+/-0.17. The mean eKt/V was 1.16+/-0.14 and was inversely correlated with weight and water volume (p < 0.0001). Despite the large dialyzers and high blood and dialysate flow rates, no patient weighing more than 80 kgm or with body water volume exceeding 46 liters achieved an eKt/V of 1.45. This study suggests that creative dialyses will be required to achieve the HEMO "high arm" target in large patients.

Pesticide use and residues on Queensland wool.

To determine practices for control of louse infestation and blowfly strike in Queensland sheep flocks that are associated with organophosphorous and synthetic pyrethroid residues on wool. Information on residues was obtained from a survey of Queensland wool clips. Information on pesticide use was obtained from a trace-back postal survey. The association between pesticide use and residues was assessed using generalised linear models, controlling for potential confounding by flock location. Between 1995 and 1997 Queensland wool clips were randomly sampled. Samples were tested for the presence and amount (mg per kg of greasy wool) of organophosphorous and synthetic pyrethroid pesticides. A questionnaire seeking information on flock characteristics and pesticide use was sent to the manager of each flock from which a wool sample was tested. The median amount of OP and SP residue was 0.8 and 0.25 mg/kg, respectively, and 91 and 95% of wool samples contained < 8 mg/kg of OP and SP residues, respectively. The frequency of OP pesticide use for louse control was significantly (P = 0.005) associated with mean OP residue amount, and the timing of SP use for louse control, in relation to shearing, was significantly (P < 0.001) associated with mean SP residue amount. Most Queensland wool clips have acceptable amounts of residues after the use of OP and SP pesticides, but wool growers can further reduce residues by effectively controlling louse infestation with pesticide applications early after shearing and the use of non-chemical methods of ectoparasite control.

Cortical silent period evoked by transcranial magnetic stimulation in ischemic stroke

Objectives: Transcranial magnetic stimulation (TMS) of the motor cortex produces motor evoked potentials (MEPs). Besides this excitatory response, TMS has inhibitory effects. When TMS is performed during voluntary muscle contraction, the MEP is followed by a pause in electromyographic activity (cortical silent period, SP). Methods: We studied SP changes in 50 patients with acute hemispheric brain infarction. A stimulator with a round coil and a fixed intensity of 90% of maximum was used to evoke MEPs. Results: SP was elicited on the affected side in 29 of the 50 patients. The mean SP duration was markedly longer on the affected side in the patient group. There were no significant differences between left and right sides in the means of the MEP amplitude ratio (amplitude related to corresponding amplitudes to peripheral electric stimulation) and MEP latencies in the patient group. Prolonged SP was found in 25 of the 29 patients (86%) whereas only 4 (14%) had abnormalities in MEP latency or amplitude ratio. The mean SP duration was significantly prolonged also in a subgroup of 14 patients with normal hand function. Conclusions: The SP measurement is an easily performed and sensitive method to detect even subclinical disturbances in motor system function in ischemic stroke.

Biochemical fingerprinting of coliform bacterial populations – comparisons between polluted river water and factory effluents

Bacteria from different pollution sources may consist of essentially the same species but with different strains predominating. Therefore, sub-typing of bacterial strains recovered in the polluted water and comparison with those present in possible pollution sources is a valuable tool for identification of the source. Since such studies require investigations of large numbers of isolates, simple laboratory methods combined with automated data evaluation and presentation are necessary. The Phene Plate (PhP) system for biochemical fingerprinting of bacteria is based on measurements of the kinetics of biochemical tests, performed in micro-plates. The system also includes mathematical models to calculate the diversity (Di) of the bacterial flora within samples, as well as the similarities between bacterial populations in different samples as the population similarity coefficient (Sp). We have used the PhP system to type coliform bacteria isolated from a polluted river in Sweden and from the outlets from three paper mills that were suspected contamination sources. From each of 27 river water samples and 8 samples from factory outlets, collected on eight sampling occasions, between 10 and 50 coliforms were typed, yielding altogether 1,027 isolates. The diversity among the bacteria in river water samples was generally high (mean Di = 0.95) compared with factory outlets (mean Di = 0.63) which usually were dominated by isolates belonging to a few PhP types. These PhP types were very rarely recovered from the river water samples which is also reflected in low similarities between bacterial populations in river water and factory outlets (mean Sp = 0.03). Thus the bacteria from factory outlets did not seem to have spread downstream. In contrast, bacterial populations from sampling sites close to each other in the river were more similar to each other (mean Sp 0.13), indicating the presence of several, diffuse contamination sources, possibly from animal or human faecal material.

Biochemical fingerprinting of coliform bacterial populations — comparisons between polluted river water and factory effluents

Bacteria from different pollution sources may consist of essentially the same species but with different strains predominating. Therefore, sub-typing of bacterial strains recovered in the polluted water and comparison with those present in possible pollution sources is a valuable tool for idenlification of the source. Since such studies require investigations of large numbers of isolates, simple laboratory methods combined with automated data evaluation and presentation are necessary. The Phene Plate (PhP) system for biochemical fingerprinting of bacteria is based on measurements of the kinetics of biochemical tests, performed in micro-plates. The system also includes mathematical models to calculate the diversity (Di) of the bacterial flora within samples, as well as the similarities between bacterial populations in different samples as the population similarity coefficient (Sp). We have used the NIP system to type coliform bacteria isolated from a polluted river in Sweden and from the outlets from three paper mills that were suspected contamination sources. From each of 27 river water samples and 8 samples from factory outlets, collected on eight Sampling occasions, between 10 and 50 coliforms were typed, yielding altogether 1,027 isolates. The diversity among the bacteria in river water samples was generally high (mean Di = 0.95) compared with factory Outlets (mean Di = 0.63) which usually were dominated by isolates belonging to a few NIP types. These PhP types were very rarely recovered from the river water samples which is also reflected in low similarities between bacterial populations in river water and factory outlets (mean Sp = 0.03). Thus the bacteria from factory outlets did not seem to have spread downstream. In contrast, bacterial populations from sampling sites close to each other in the river were more similar to each other (mean Sp 0.13), indicating the presence of several, diffuse contamination sources, possibly from animal or human faecal material.

A practical anesthesia monitoring protocol for free-ranging adult African elephants (Loxodonta africana).

Twenty free-ranging adult African elephants (Loxodonta africana) in northern Botswana were immobilized with a mean (+/- SD) of 9.5 +/- 0.5 mg etorphine hydrochloride and 2,000 IU hyaluronidase by intramuscular (IM) dart. The mean time to recumbency was 8.7 +/- 2.4 min. All animals were maintained in lateral recumbency. The anesthesia monitoring protocol included cardiothoracic auscultation; palpation of auricular pulse for quality and regularity; checking of rectal temperature, and monitoring of respiratory and heart rates. Results of basic physiologic measurements were similar to those of previous field studies of African elephants immobilized with etorphine or etorphine-hyaluronidase. In addition, continuous real-time pulse rate and percent oxygen saturation of hemoglobin (SpO2) readings were obtained on 16 elephants with a portable pulse oximeter. Duration of pulse oximetry monitoring ranged from 3 to 24 min (mean +/- SD = 8.2 +/- 4.8 min). Differences between minimum and maximum SpO2 values for any given elephant ranged from 1 to 6 percentage points, evidence for relatively stable trends. The SpO2 readings ranged from 70% to 96% among the 16 elephants, with a mean of 87.3 +/- 2.8%. Fifteen of 16 elephants monitored with a pulse oximeter had mean SpO2 values > or = 81 +/- 2.4%, with 11 having mean SpO2 values > or = 85 +/- 1.5%. All 20 animals recovered uneventfully following reversal: diprenorphine at 23.3 +/- 1.5 mg intravenous (IV) with 11.7 +/- 0.5 mg IM, or 24 mg diprenorphine given all IV.

Seminal plasma zinc analysis and bacteriological cultures in chronic staphylococcal prostatitis.

Seminal plasma zinc (SP Zn) determinations were undertaken in 22 patients suspected of having chronic bacterial prostatitis and in 12 normal subjects free from prostatic infection. Of the 20 patients with positive Staphylococcus culture 17 (85%) showed the same bacterial growth in urethral urine with no significant difference in colony counts (P > 0.005). Mean SP Zn concentration in seminal plasma of 20 patients (164.69 +/- 122.25 mg/ml) was not significantly different in comparison with the control group (168.47 +/- 123.01 mg/ml) (P = 0.755). Mean SP Zn concentration of 3 (15%) patients (156.95 +/- 98.44 mg/ml), with staphylococcal infection bacteriologically localized to the prostate was not significantly different from those of the control group (P = 0.77). We believe that assays of SP Zn content might aid in the confirmation of the role of Staphylococcus in the aetiology of chronic prostatis in larger patient groups.

Parathyroid function in end-stage penal failure

To clarify the degree of parathyroid dysfunction in end-stage renal failure, sigmoidal relationship between serum Ca2+ and intact-PTH was evaluated in vivo in 47 hemodialysis (HD) patients including 12 diabetics. Patients were divided into 3 groups, 9 who had been just introduced to HD (0 years), 31 who were on maintenance HD for 2.5 to 16.2 years without significant secondary hyperparathyroidism (2nd HPT), and 7 who suffered from severe 2nd HPT for 8.5 to 15.3 years on HD. Additional 4 patients who were treated with HD or hemodiafiltration because of acute hepatic failure with normal renal function were selected for control. Sigmoidal curve (SC) in patients with non-diabetics on 0 years on HD was significantly deviated to upper and right direction. Similarly, the set point of calcium (SP) in non-diabetics was deviated to the right (higher calcium level). These abnormalities were more pronounced as the length of HD duration increased. However, these parathyroid dysfunction was not obvious in diabetic patients. In severe 2nd HPT, SC and SP were remarkably deranged. Mean SP in these patients was 1.22 mmol/l, and 1.26 mmol/l in 3 patients who required parathyroidectomy after the study. These results indicate that the earlier treatment to prevent 2nd HPT would be necessary from conservative stage of renal failure in non-diabetic population.

Analysis of phenolic compounds in relation to the prediction of digestibility and toxicity of ammonia-treated cereal straws

Thirty-five samples of cereal straws were collected from farms in southern Spain before and after treatment with ammonia (35 g NH 3 kg −1 straw) in sealed plastic-covered stacks. Seven of the treated straws produced symptoms of acute toxicity (hyperexcitability) when fed to sheep and cattle. Total phenolic content (TP), phenolic material solubilised by water extraction of straws at 70 °C (SP) and residual, water-insoluble phenolics (RP) were measured by the acetyl bromide method. No significant differences were found between the mean TP or RP content of untreated (136 ± 9 g kg −1 straw and 112 ± 9 g kg −1 straw, respectively) and treated straws (145 ± 21 g kg −1 straw and 107 ± 9 g kg −1 straw, respectively). Ammonia treatment did not significantly increase the water solubility of the phenolic fraction of the non-toxic straws examined. The mean SP content of toxic straws however, was found to be three to four times greater (91 g kg −1 straw) than non-toxic treated straws (24 g kg −1 straw), this difference being reflected in the TP values which were approximately 30% higher in the toxic samples. A significantly higher proportion of added nitrogen was fixed in the toxic straws compared with their non-toxic counterparts. Limited analysis of SP fractions from toxic straws by thinlayer chromatography and gas chromatography-mass spectroscopy failed to reveal any compound which co-chromatographed with reference imidazoles including 4- O-methyl imidazole. Thin-layer chromatography fractionation showed qualitative differences between SP fractions from toxic and non-toxic straws but the compounds involved were not identified. Results obtained suggest that soluble phenolics do not provide a means of predicting the digestibility of ammonia-treated straw but that a substantially elevated soluble phenolic content is indicative of potential toxicity.

Doppler ultrasonic brachial blood pressure measurements in normal Chinese neonates: a preliminary report.

The purpose of this study was to determine brachial blood pressures in normal Chinese neonates using a Doppler ultrasonic blood pressure monitor (Roche Arteriosonde 1020). The systolic (SP) and diastolic (DP) pressures of 100 healthy, full-term Chinese neonates were determined in triplicate under resting conditions. The pulse pressures (PP) were derived from the SP and DP. Correlation studies reveal significant positive correlation between age and PP (r = 0.34, P less than 0.0002), between weight and SP (r = 0.23, P less than 0.02) and between weight and PP (r = 0.40, P less than 0.02). No significant difference exists between blood pressures of males and females (P greater than 0.05). Comparison with three Western studies reveals that our mean SP is the lowest (1-3). This may be due to technical factors, e.g. different Doppler ultrasonic device, anthropometric factors or true genetic or environmental differences.

Serum SP 1 and hCGβ-subunit (hCGβ) levels in choriocarcinoma, invasive mole, and hydatidiform mole—Clinical significance of [formula omitted] ratio

Serum SP 1 (pregnancy-specific β 1, glycoprotein) levels in patients with choriocarcinoma, invasive mole, and hydatidiform mole were radioimmunoassayed and compared with simultaneously measured serum hCGβ-subunit (hCGβ) levels in order to evaluate the clinical significance of SP 1 determination. Serum SP 1 levels at the time of admission ranged from 6.4 to 1660 ng/ml in choriocarcinoma patients, 16.3 to 540 ng/ml in invasive mole, and 720 to 58,000 ng/ml in hydatidiform mole. SP 1 hCGβ ratios were under 1.0 in choriocarcinoma (0.3 ± 0.2, mean ± SD), over 1.0 in hydatidiform mole (10.9 ± 8.3), and intermediate in invasive mole (1.5 ± 0.3). In normal pregnancy, the ratio increases as pregnancy progresses, that is, from 15.25 in 7-week gestation to 14,090.90 in 40-week gestation. The mean SP 1 hCGβ ratio differs significantly among choriocarcinoma, invasive mole, and hydatidiform mole. SP 1 hCGβ ratio is likely to represent the degree of differentiation of trophoblastic cells. The SP 1 hCGβ ratio may be useful in differentiating between choriocarcinoma and invasive mole.