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At least 307 records · Page 17Linked to original sources
PubMed1989

A mathematical model of erythropoiesis in mice and rats. Part 2: Stimulated erythropoiesis.

A mathematical model of erythropoietic cell production and its regulation process has been proposed in a preceding paper. It is primarily based on the assumption that the number of cell divisions taking place in the CFU-E and erythropoietic precursor stages is regulated depending on the oxygen supply of the tissue. Quantitative dose-response relationships for in vivo erythropoiesis are suggested. Here, we demonstrate that this model adequately reproduces data obtained in situations of stimulated erythropoiesis in mice and rats. In detail, this implies a quantitative description of the following processes: (1) Changes in tissue oxygen tension (Pto2) following removal of red cells (bleeding, haemolytic anaemia) or increase in plasma volume (dilution anaemia) or decrease in atmospheric oxygen pressure (hypoxia). (2) Pto2 dependent erythropoietin (EPO) production. (3) Dose-response of EPO on erythropoietic amplification (up to two to four additional mitoses). (4) The changes of the marrow transit time. Model simulations are compared with experimental data for changes of erythropoiesis during hypoxia, EPO-injection, and different forms of anaemia. A satisfactory agreement suggests that the model adequately describes and correlates different direct and indirect ways to stimulate erythropoiesis. It quantifies the role and relative contribution of the haematocrit, haemoglobin concentration, atmospheric oxygen pressure, tissue oxygen pressure, and plasma volume as triggers in erythropoietic stimulation under various conditions. Furthermore, the model may allow to optimize the scheme of EPO-administration and to find the maximum increase of erythropoiesis for a given amount of erythropoietin.

Anemia↗
PubMed1998

Comparison of spontaneous frontal EMG, EEG power spectrum and bispectral index to monitor propofol drug effect and emergence.

BACKGROUND: The aim of this study was to investigate the accuracy of frontal spontaneous electromyography (SEMG) and EEG spectral edge frequency (SEF 95%), median frequency (MF), relative delta power (RDELTA) and bispectral index (BIS) in monitoring loss of and return of consciousness and hypnotic drug effect during propofol administration at different calculated plasma target concentrations. METHODS: Propofol was administered by using a target-controlled infusion at different propofol steady-state concentrations. All variables were measured simultaneously at specific calculated concentrations and endpoints. RESULTS: Loss of consciousness was accurately monitored by BIS, SEMG and SEF 95%, and propofol drug effect by BIS only. Return of consciousness was predicted by BIS, MF and SEF 95%. Due to the biphasic EEG pattern of propofol and the lack of reproducible data at specific propofol concentrations, the clinical usefulness of SEF 95%, MF and RDELTA was very limited. SEMG was useful to detect loss and return of consciousness, but without predictive value. CONCLUSIONS: The BIS might be an accurate measure to monitor depth of anaesthesia and hypnotic drug effect. Other neurophysiologic measures have limited value to monitor depth of anaesthesia and hypnotic drug effect.

Adult↗
PubMed2005

Regional differences in responses of rabbit detrusor to electrical and adrenergic stimulation: influence of outlet obstruction.

OBJECTIVE: To examine regional responses of control and obstructed rabbit detrusor strips to electrical and adrenergic stimulation, and determine whether outlet obstruction causes regional variations in blood flow throughout the detrusor, as the detrusor smooth muscle of the bladder body has previously been considered homogeneous in its pharmacological properties. MATERIALS AND METHODS: Fourteen male rabbits had the bladder outlet surgically obstructed for 2 weeks and were compared with 10 unoperated control rabbits. Blood flow was measured with the bladder empty and at capacity, using fluorescent microspheres. Paired dorsal and ventral strips were harvested from the midline equatorial detrusor and electrically and adrenergically stimulated. RESULTS: Obstructed rabbits had significantly higher bladder capacities and bladder weights than control rabbits. Dorsal strips from both control and obstructed rabbits contracted in response to noradrenaline, whereas ventral strips relaxed. The addition of prazosin, a nonselective alpha1-adrenergic-receptor blocker, completely blocked the contraction in dorsal strips, but had no effect on responses of ventral strips. There was also a regional difference in response to electrical stimulation, with ventral strips generating significantly more tension than dorsal strips in both control and obstructed rabbits. There were no regional differences in detrusor blood flow. Obstruction resulted in significantly lower responses to all forms of stimulation, and significantly less blood flow throughout the detrusor. CONCLUSION: There are regional differences in adrenergic receptor function and response to electrical-field stimulation throughout control and obstructed rabbit detrusor, a region that was previously thought to be functionally homogeneous. These differences must be recognized and acknowledged to obtain accurate and reproducible data from in vitro studies of the bladder.

Adrenergic alpha-Antagonists↗
PubMed1994

A time to be born: implications of animal studies in maternal-fetal medicine.

Recent studies on the capabilities of the fetus in the last third of gestation demonstrated that the fetus actively prepares for its journey to the extrauterine environment. The most remarkable of these preparations is that the fetal brain gives the signal to begin the birth process. Several studies, particularly those conducted in sheep, showed that endocrine signals from the fetal brain are sent to the placenta to stimulate increased estrogen production. The increased estrogen production initiates uterine contractility, and starts the labor process. The mother's oxytocin production also plays a role by determining the precise time of the day that the baby is born. These studies produced fascinating insights into fetal and uterine physiology that have already begun to be employed in clinical care. One primary example in the application of this new knowledge obtained originally from studies on fetal sheep is in understanding the endocrine regulation of fetal production of surfactant to treat women in preterm labor and to produce artificial surfactants for the treatment of babies delivered too early. It is important to obtain and use reproducible data gained from carefully controlled animal experiments to rationalize clinical management practices. Basic research should precede changes in clinical management, rather than follow them, as is so often the case.

Brain↗
PubMed2006

Quantitative electroencephalography values of neonates during and after venoarterial extracorporeal membrane oxygenation and permanent ligation of right common carotid artery.

Venoarterial extracorporeal membrane oxygenation (ECMO) in neonates commonly needs neck vessel cannulation leading to ligation of right common carotid artery (RCCA) in some cases. Quantitative electroencephalography (EEG) measurements provide reproducible data of cerebral function. The aim of this case-control study was to test whether ligation of the RCCA results in EEG changes after ECMO weaning. Ten mechanically ventilated neonates not treated with ECMO were eligible as control patients. Seven ECMO patients receiving similar sedoanalgesia were investigated during and after ECMO and RCCA ligation. Dominant frequency, absolute alpha, theta, delta, and total powers of right and left frontocentral and temporooccipital derivations were calculated. Dominant frequency did not differ among groups. Power was found to be significantly decreased in all frequency bands during ECMO. After weaning from ECMO, EEG differences between the ECMO and control groups disappeared in spite of permanent RCCA ligation. It is concluded that ligation of the RCCA per se does not result in quantitative EEG changes.

Carotid Artery, Common↗
PubMedDate not supplied

Computer analysis of the fetal heart rate.

Computer analysis of the fetal heart rate is a technology of the Information Age commercially available for research and clinical practice. Intelligent systems are engineered with algorithms or neural networks designed to simulate expert knowledge. Automated analysis has provided objective, standardized, and reproducible data used to research fetal heart rate responses in the antepartum and intrapartum setting. Perinatal information systems can integrate FHR analysis and data management.

Algorithms↗
PubMed2002

Reliability, validity, and responsiveness of severity of dyspepsia assessment (SODA) in a randomized clinical trial of a COX-2-specific inhibitor and traditional NSAID therapy.

OBJECTIVES: We aimed to assess the Severity of Dyspepsia Assessment (SODA) scales as measures of change in dyspepsia-related health in a blinded, randomized, controlled trial in arthritis patients treated with nonsteroidal anti-inflammatory drugs. METHODS: Three thousand nine hundred seven arthritis patients completed SODA at baseline and weeks 4, 13, 26, and 52 and/or at early termination. Using baseline and 4-wk data, reliability was evaluated with Cronbach's a and the intraclass correlation coefficient (ICC). Dyspepsia adverse events were defined based on a combined set of World Health Organization Adverse Reaction Terminology terms. The ability of SODA to measure change in dyspepsia-related health was evaluated by comparing SODA change scores by dyspepsia adverse event severity level and withdrawal status. Responsiveness was further evaluated by the area under the curve (AUC) from receiver operating characteristic curves using withdrawal due to dyspepsia as the criterion. RESULTS: The SODA scales--Pain Intensity (alpha = 0.93), Non Pain Symptoms (alpha = 0.82), and Satisfaction (alpha = 0.89)--demonstrated excellent internal consistency reliability using baseline data. Reproducibility was fair to good: Pain Intensity ICC = 0.49, Non Pain Symptoms ICC = 0.61, and Satisfaction ICC = 0.45. SODA change scores (4-wk score - baseline score) increased, or worsened, with increasing dyspepsia severity and differentiated between adjacent levels of dyspepsia severity for eight of nine adjacent comparisons (p < 0.05). SODA change scores also differentiated between those who did and did not withdraw (p < 0.001). Responsiveness was highest with the Pain Intensity scale (AUC = 0.78), followed by the Non Pain Symptoms (AUC = 0.74) and Satisfaction (AUC = 0.75) scales. CONCLUSIONS: SODA is a reliable, valid instrument for use as a measure of dyspepsia tolerability in future clinical trials involving cyclo-oxygenase-2-specific and/or traditional nonsteroidal anti-inflammatory drugs.

Adult↗
PubMed1989

A comparison between stereological estimates of mean nuclear volume and DNA flow cytometry in bladder tumours.

The correlation between stereological estimate of mean nuclear volume and DNA-content was studied in 55 human urinary bladder tumours. The DNA-content was determined by flow cytometry on isolated nuclei stained with ethidium bromide. Trout erythrocytes were used as a biological internal standard providing an accurate determination of the DNA-histogram. An unbiased estimate of the mean nuclear volume (vv) was obtained after standard formaline fixation, paraffin-embedding, sectioning and hematoxylin-eosin staining using the equation vv = pi/3.l3(0). Here l0 is the length of an intercept measured in a random direction through a test point, which hit a nucleus. A highly significant correlation was found between vv and mean DNA-content of nuclei (2p = 0.0004). A highly significant correlation was also found between vv and the highest DNA-content present in tumours having cell populations with different DNA content (2p = 0.0016). The mean nuclear volume and the DNA-content also correlated well with the pathologic grade. Although significant the correlations were far from perfect, which indicates that DNA content and mean nuclear volume may provide partly independent biological information. The methods provide objective, unbiased and reproducible data which may improve the possibility of grading and predicting the disease course of human urinary bladder tumours.

Cell Nucleus↗
PubMed1977

Percutaneous cardiac puncture in domestic pigs.

Blood sampling by percutaneous cardiac puncture was carried out in 69 domestic pigs. The procedure was shown to be safe and to produce reproducible data. The technique can be carried out without anaesthesia. Repeated sampling is possible over minutes, hours or days, and a wide range of sample volumes can be achieved by this technique.

Animals↗
PubMed1994

Longitudinal monitoring of intracranial arterial stenoses with transcranial Doppler ultrasonography.

The natural history of intracranial arterial stenoses remains relatively unknown. To monitor the progression of these lesions over time, the authors reviewed transcranial Doppler (TCD) laboratory reports at five hospitals for patients with angiographically documented intracranial arterial stenoses along the internal carotid artery distribution, and at least two TCD studies conducted more than 2 months apart. Twenty-two patients (19 men and 3 women; mean age, 64 years) with 29 stenoses were identified. The findings were compared to reproducibility data obtained from 11 age-matched control subjects with repeat TCD studies. During a mean follow-up period of 21 months, peak systolic flow velocities corresponding to the areas of stenosis increased in 9 arteries with lesions, and new collateral flow patterns, indicating further hemodynamic compromise distal to the lesions, developed in 2; one of the latter also had increased corresponding velocities. Thus, 10 (35%) arteries with lesions had TCD evidence of progression. Flow velocities remained the same in 13 (45%) stenotic vessels and dropped in 2 (7%). Findings were considered inconclusive for 4 lesions (14%). These findings suggest that intracranial arterial stenoses are dynamic lesions, and that they can evolve and cause further reductions of the arterial diameters after relatively short periods of time. TCD can noninvasively detect their hemodynamic effects.

Adult↗
PubMed1999

Sound localization in noise in hearing-impaired listeners.

The present study assesses the ability of four listeners with high-frequency, bilateral symmetrical sensorineural hearing loss to localize and detect a broadband click train in the frontal-horizontal plane, in quiet and in the presence of a white noise. The speaker array and stimuli are identical to those described by Lorenzi et al. (in press). The results show that: (1) localization performance is only slightly poorer in hearing-impaired listeners than in normal-hearing listeners when noise is at 0 deg azimuth, (2) localization performance begins to decrease at higher signal-to-noise ratios for hearing-impaired listeners than for normal-hearing listeners when noise is at +/- 90 deg azimuth, and (3) the performance of hearing-impaired listeners is less consistent when noise is at +/- 90 deg azimuth than at 0 deg azimuth. The effects of a high-frequency hearing loss were also studied by measuring the ability of normal-hearing listeners to localize the low-pass filtered version of the clicks. The data reproduce the effects of noise on three out of the four hearing-impaired listeners when noise is at 0 deg azimuth. They reproduce the effects of noise on only two out of the four hearing-impaired listeners when noise is at +/- 90 deg azimuth. The additional effects of a low-frequency hearing loss were investigated by attenuating the low-pass filtered clicks and the noise by 20 dB. The results show that attenuation does not strongly affect localization accuracy for normal-hearing listeners. Measurements of the clicks' detectability indicate that the hearing-impaired listeners who show the poorest localization accuracy also show the poorest ability to detect the clicks. The inaudibility of high frequencies, "distortions," and reduced detectability of the signal are assumed to have caused the poorer-than-normal localization accuracy for hearing-impaired listeners.

Aged↗
PubMed1989

Minimum antibiotic levels for selecting a resistance plasmid in a gnotobiotic animal model.

The minimum antibiotic concentrations for selecting an R plasmid in vivo were determined in germfree mice colonized by two isogenic strains of Escherichia coli, one of which carried an R plasmid. Seventy groups of three gnotobiotic mice were given low doses of ampicillin, colistin, flumequin, gentamicin, tetracycline, or streptomycin via drinking water for 2 weeks. The equilibrium between susceptible and resistant populations of bacteria was monitored daily in feces and compared with that of control mice given pure water. This model yielded reproducible data, and dose and response were strongly correlated. The minimum selecting doses ranged from 0.9 to 12.8 micrograms/ml of water, depending on the antibiotic and the R plasmid. The use of mathematical models and complementary in vitro experiments accounted for the effect of the low antibiotic levels.

Animals↗
PubMed2002

Quantification of substance p mRNA in human immune cells by real-time reverse transcriptase PCR assay.

We have applied a newly developed real-time reverse transcriptase (RT) PCR (RT-PCR) assay for quantification of substance P (SP) mRNA expression (the SP real-time RT-PCR assay) in human blood monocyte-derived macrophages, peripheral blood lymphocytes, and microglia isolated from fetal brain. The SP real-time RT-PCR assay had a sensitivity of 60 mRNA copies, with a dynamic range of detection between 60 and 600,000 copies of the SP gene transcript per reaction mixture. The coefficient of variation of the threshold cycle number between the SP real-time RT-PCR assays was less than 1.16%. This assay with an SP-specific primer pair efficiently recognizes all four isoforms of preprotachykinin A (the SP precursor) gene transcripts. In order to use this assay to measure the levels of SP mRNA in the human immune cells quantitatively, we designed a specific probe (molecular beacon) derived from exon 3 of the SP gene. We demonstrated that the real-time RT-PCR quantitatively detected SP mRNA in the human immune cells, among which the microglia isolated from fetal brain had the highest levels of SP mRNA. The SP real-time PCR assay yielded reproducible data, as the intra-assay variation was less than 1%. Thus, it is feasible to apply the real-time RT-PCR assay for quantification of SP mRNA levels in human immune cells, as well as in other nonneuronal cells. Since SP is a major modulator of neuroimmunoregulation, this assay has the potential for widespread application for basic and clinical investigations.

Adult↗
PubMed1988

Homogeneous liposome lysis assay for determination of anti-streptolysin O antibody titer in serum.

We developed a liposome lysis assay for determining anti-streptolysin O antibodies (ASO) in human sera involving the use of carboxyfluorescein-entrapped multilamellar liposomes. This assay system was based on the inhibition of streptolysin O-induced liposome lysis by ASO. Briefly, after incubation of a given amount of streptolysin O with ASO for 30 min at 37 degrees C, carboxyfluorescein-entrapped liposomes composed of egg yolk phosphatidylcholine and cholesterol in a molar ratio of 1:1 were added to the mixture to determine the residual streptolysin O activity. Liposome lysis, detected as carboxyfluorescein release from the liposomes, was inversely proportional to the ASO titer. The results of within-run and between-run precision studies indicated that the liposome lysis assay is accurate and gives reproducible data. Bilirubin, hemoglobin, and triglycerides did not interfere with the liposome lysis assay. The ASO titers of 100 patient sera, evaluated by our new method and the Rantz-Randall method, showed good correlation.

Antistreptolysin↗
PubMed1996

Comparative assessment of Etest for testing susceptibilities of Neisseria gonorrhoeae to penicillin, tetracycline, ceftriaxone, cefotaxime, and ciprofloxacin: investigation using 510(k) review criteria, recommended by the Food and Drug Administration.

We evaluated the ability of the Etest (AB Biodisk, Solna, Sweden) method to accurately and reproducibly determine the antimicrobial susceptibility of Neisseria gonorrhoeae. One hundred gonococcal isolates were used to evaluate the diagnostic performance of the Etest compared with the reference agar dilution method for penicillin, tetracycline, ciprofloxacin, and ceftriaxone. Between 92 and 99% of Etest MIC results for all drugs were within +/- 1 log2 dilution of the reference MIC. According to recommended interpretive criteria, ceftriaxone, cefotaxime, and ciprofloxacin had 100% categorical agreement, while penicillin (86%) and tetracycline (85%) categorical agreement percentages were lower because of the large number of strains that were within 0.5 to 1 log2 dilution of the susceptible or resistant breakpoints. Reproducibility data also demonstrated that the Etest was precise (99.1%) when subjected to replicate testing. On the basis of these data, the Etest method provides an effective, simple alternative to the reference agar dilution method for the direct quantification of N. gonorrhoeae susceptibility.

Cefotaxime↗
PubMed2004

Use of insertion sequence element IS1126 in a genotyping and transmission study of Porphyromonas gingivalis.

Porphyromonas gingivalis is strongly associated with periodontal diseases and is regarded as one of the risk factors for periodontitis. Insertion sequence element IS1126-based PCR was used to investigate the genetic heterogeneity of P. gingivalis from periodontitis patients and to examine the frequency of the parent-child and spouse-spouse transmission. Two sets of IS1126-specific primers were used for the PCR. The inward primer set (PI1 and PI2), which amplifies the IS1126 fragment of approximately 690 bp, was used to identify P. gingivalis. The outward primer set (PI1RC and PI2RC), which is reverse complementary to PI1 and PI2, respectively, and amplifies the gene fragments between the adjacent IS1126 elements was used to characterize the genotypes of the P. gingivalis strains. PCR of P. gingivalis with PI1RC and PI2RC resulted in the production of two to seven amplicons, which showed a unique electrophoretic pattern in each strain (4 laboratory strains and 37 clinical isolates cultured from 12 patients with aggressive periodontitis). The usefulness of the method for transmission study was confirmed by detecting identical genotypes between the isolates and the plaque samples from which the isolates were cultured and between the plaque samples from different tooth sites in the same patient. Thirty probands with periodontal diseases and their thirty immediate family members were included in the transmission study. In 11 of 14 parent-child pairs (78.6%), P. gingivalis revealed an identical or similar band pattern, whereas 5 of 16 spouse pairs (31.25%) had this similarity. These results show that IS1126-based PCR for genotyping P. gingivalis has a highly discriminating potential with reproducible data and is a simple and reliable method for a transmission study.

Adult↗
PubMed2005

Use of a three-dimensional microarray system for detection of levofloxacin resistance and the mec A gene in Staphylococcus aureus.

We evaluated a novel three-dimensional microarray (Pam Chip microarray) system to detect the presence of levofloxacin-related resistance mutations and the mec A gene. The results were compared to those obtained for 27 Staphylococcus aureus isolates by conventional DNA sequencing or PCR methods. Hybridization and fluorescence detection were performed using an FD 10 system designed for Pam Chip microarray under conditions optimized for each target/probe on the array. In dilution series analysis using multiplex PCR samples, the sensitivity of the microarray was about 10 times greater than that of conventional PCR methods. A high level of data reproducibility was also confirmed in those analyses. Various point mutations in quinolone resistance-determining regions detected by our system corresponded perfectly to the results obtained by conventional DNA sequencing. The results of the mec A gene detection using our system also corresponded to the PCR method; that is, signal/band was detected in all isolates of methicillin-resistant S. aureus, and no signal/band was detected in any isolate of methicillin-susceptible S. aureus. In conclusion, our novel three-dimensional microarray system provided rapid, specific, easy, and reproducible results for the simultaneous detection of levofloxacin resistance and the mec A gene in S. aureus.

Anti-Bacterial Agents↗