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At least 397 records · Page 22Linked to original sources
PubMed1999

Comparison of transcranial Doppler flow velocity and cerebral blood flow during focal ischemia in rabbits.

The predictive value of transcranial Doppler (TCD) cerebral blood flow velocity (CBFV) measurements for cerebral blood flow (CBF) calculations in humans is still controversial, and experimental correlative studies are lacking. The aim of the present study was to validate TCD signals of CBFV during focal cerebral ischemia. Therefore, CBFV determined in the middle cerebral artery (MCA) was compared with values of CBF obtained from autoradiograms of ischemic brain areas. To determine CBFV, a transcranial Doppler ultrasound probe (TCD) adapted to small sample volumes was used in 9 rabbits. CBF was quantified after a final infusion of [14C]-iodoantipyrine in the same animals. For focal cerebral ischemia induction, two threads were flushed upward simultaneously into the internal carotid artery, resulting in a flow reduction in the ipsilateral MCA. After thread occlusion, mean systolic CBFV in the MCA decreased from 49 +/- 9 cm/s to 22 +/- 3 cm/s. CBF in the caudate nucleus was reduced (19 +/- 8 mL/100 g/min) compared to the contralateral nonischemic side (52 +/- 18 mL/100 g/min). The decrease in hemispheric CBF correlated well with the decrease in both mean systolic (r = 0.97) and diastolic (r = 0.94) CBFV in the MCA (p < 0.01). The decrease in CBFV determined by transcranial Doppler ultrasound in the MCA appears to reflect the reduction in CBF in the affected brain hemisphere and can be used as a quantitative in vivo parameter for tissue perfusion.

Animals↗
PubMed1998

An ecological-transactional analysis of children and contexts: the longitudinal interplay among child maltreatment, community violence, and children's symptomatology.

Cicchetti and Lynch have conceptualized ecological contexts as consisting of nested levels with varying degrees of proximity to the individual. These levels of the environment interact and transact with each other over time in shaping individual development and adaptation. With a sample of maltreated (n = 188) and nonmaltreated (n = 134) children between the ages of 7 and 12 years, this investigation employed a 1-year longitudinal design to conduct an ecological-transactional analysis of the mutual relationships among community violence, child maltreatment, and children's functioning over time. Indicators of children's functioning were externalizing and internalizing behavior problems and self-rated traumatic stress reactions, depressive symptomatology, and self-esteem. Either full or partial support was obtained for the study's primary hypotheses. Rates of maltreatment, particularly physical abuse, were related to levels of child-reported violence in the community. In addition, child maltreatment and exposure to community violence were related to different aspects of children's functioning. Specific effects were observed for neglect and sexual abuse and for witnessing and being victimized by violence in the community. Finally, there was evidence that children and their contexts mutually influence each other over time. Results were discussed within the framework of an ecological-transactional model of development.

Aggression↗
PubMed2002

Label-free parallel screening of combinatorial triazine libraries using reflectometric interference spectroscopy.

The parallel reflectometric interference spectroscopy is presented as a label-free optical detection method. A new setup was adapted to accommodate sample carriers in a 96-well microplate. It allows for the first time simultaneous plate imaging by a CCD camera for the parallel detection of specific biomolecular interaction in the microplate wells at heterogeneous phase using direct optical monitoring. The detection of binding events with time resolution enables a highly parallel functional biomolecular interaction analysis (BIA). The combination of this new screening setup with combinatorial solid-phase synthesis is performed in the wells of glass-bottom microplates to accomplish the synthesis and the screening platform within one device. As a model system for a solid-phase substance library, synthesis of a triazine library and the subsequent BIA with four different antibodies were carried out. The presented setup enables a time resolution of 18 s with a total screening time of less than 35 min including baseline adjustment, BIA, and regeneration of the screening device for 96 samples in parallel. The binding studies reveal a fast classification of the different monoclonal and polyclonal antibodies and enable the detection of triazines with high binding affinity. The presented prototype is the first parallelized optical label-free detection system for biomolecular interaction analysis that is suitable for a high-throughput screening based on the 96-well microplate format.

Antibodies↗
PubMed1990

Fluorescence analysis of the size of a binding pocket of a peptide receptor at natural abundance.

We have studied the topography of interaction of a family of fluorescent formyl peptides containing four (CHO-Met-Leu-Phe-Lys-fluorescein), five (CHO-Met-Leu-Phe-Phe-Lys- fluorescein), and six (CHO-Nle-Leu-Phe-Nle-Tyr-Lys-fluorescein and CHO-Met-Leu-Phe-Phe-Phe-Lys- fluorescein) amino acids with their receptor using spectroscopic methods adapted to small sample volumes. Only the fluorescent peptides containing four and five amino acids were quenched upon binding to the receptor, indicating physical contact of the chromophore with the receptor. In contrast, only the hexapeptides were accessible to antibodies to fluorescein. Taken together, these results suggest that the carboxy terminus of the tetrapeptide or the pentapeptide is protected in the receptor binding pocket while the fluorescein on the carboxy terminus of either hexapeptide is exposed and recognized by the antibody to fluorescein. These results indicate that the binding pocket accommodates at least five but no more than six amino acids.

Amino Acid Sequence↗
PubMed1999

Community services for rape survivors: enhancing psychological well-being or increasing trauma?

This research examined how contact with the legal, medical, and mental health systems affects rape survivors' psychological well-being. Although community services may be beneficial for some victims, there is increasing evidence that they can add trauma, rather than alleviate distress (termed secondary victimization). This study examined how secondary victimization affects rape survivors' posttraumatic stress (PTS) symptoms. Adaptive and snowball sampling were used to recruit a sample of 102 rape survivors. Victims of nonstranger rape who received minimal assistance from either the legal or medical system, and encountered victim-blaming behaviors from system personnel, had significantly elevated levels of PTS. This high-risk group of rape survivors had PTS levels significantly higher than all other victims in this study, including those who did not seek community assistance postrape. However, for these high-risk rape survivors, receiving sustained mental health services after these negative experiences was associated with a significant decrease in PTS.

Adolescent↗
PubMed2003

Reference values of electrolyte plasma concentrations in healthy piglets during the first 48 hours of life.

The aim of this study was to analyse the plasma concentrations of sodium (Na), magnesium (Mg), calcium (Ca), inorganic phosphate (P) and potassium (K) in mature, healthy suckling pigs during the first 2 days of life in order to obtain more detailed information about this aspect of the neonatal adaptation period. Blood samples were taken from 120 suckling piglets (30 min after birth, and then at 6, 24 and 48 h post-natum). The control group consisted of 60 piglets at the ages of 1 and 2 weeks. All electrolyte concentrations showed a significant age influence (P < 0.001). Thirty minutes post-partum a significant correlation between body temperature (T) and both Mg (P < 0.05; b = -0.13) and Ca (P < 0.05, b = -0.09) could be shown. In the sixth hour of life, there was a significant dependency between Ca (P < 0.05, b = 0.48) and body mass, whereas a relationship to sex could be established for P (P < 0.05). After the twenty-fourth hour of life, there was a significant relationship between body T and both Mg (P < 0.05, b = -2.26) and P (P < 0.05, b = -6.54), as well as between body mass and Ca (P < 0.001, b = 0.89). After the forty-eighth hour of life, statistically significant correlations between body mass and Na (P < 0.05, b = 25.72), P (P < 0.05, b = 4.92), and Ca (P < 0.001, b = 1.61) became apparent. At this point, K showed a significant dependency on T (P < 0.05, b = -0.80). It may thus be hypothesized that in the first phase following birth, disturbances in temperature regulation exert a primary influence on the level of neonatal vitality, whereas body weight becomes a deciding factor at a later point in time.

Animals↗
PubMed1987

[Ceratopogonidae (Diptera) of the Congolese Mayombe. II. Contribution to the study of a Culicoides community].

Owing to adapted methods of sampling and regular captures carried out during one year, the study of a Culicoides community could be realized in the Mayombe mountain in Congo. Nineteen species were recorded. Quantity and frequency of each of them have been computed. For the principal species feeding habits, phototaxis, sex-ratio, seasonal fluctuations are analysed. Influence of climatic parameters is discussed.

Animals↗
PubMed1971

Cytological and biochemical correlation of late X-chromosome replication and gene inactivation in the mule.

The correlation between late X-chromosome replication and the quantitation of different X-linked glucose-6-phosphate dehydrogenase electrophoretic forms was studied in a natural hybrid, the female mule. In all four animals examined, a significant deviation from the expected 1: 1 ratio of random X-chromosome inactivation was observed, with the donkey X-chromosome the more frequently late-replicating one. The relative amounts of horse and donkey enzymes activities in lysates of mule skin fibroblasts and in peripheral blood were in agreement with this finding: the donkey enzyme was the minor component. Although random expression of the enzymes from the two parent species was not observed, sampling, selection, or adaptation may actually be responsible for the apparent "preferential inactivation". These studies support the hypothesis that late DNA replication indicates genetic inactivation.

Acetates↗
PubMed2003

Classification of prostatic carcinoma with artificial neural networks using comparative genomic hybridization and quantitative stereological data.

Staging of prostate cancer is a mainstay of treatment decisions and prognostication. In the present study, 50 pT2N0 and 28 pT3N0 prostatic adenocarcinomas were characterized by Gleason grading, comparative genomic hybridization (CGH), and histological texture analysis based on principles of stereology and stochastic geometry. The cases were classified by learning vector quantization and support vector machines. The quality of classification was tested by cross-validation. Correct prediction of stage from primary tumor data was possible with an accuracy of 74-80% from different data sets. The accuracy of prediction was similar when the Gleason score was used as input variable, when stereological data were used, or when a combination of CGH data and stereological data was used. The results of classification by learning vector quantization were slightly better than those by support vector machines. A method is briefly sketched by which training of neural networks can be adapted to unequal sample sizes per class. Progression from pT2 to pT3 prostate cancer is correlated with complex changes of the epithelial cells in terms of volume fraction, of surface area, and of second-order stereological properties. Genetically, this progression is accompanied by a significant global increase in losses and gains of DNA, and specifically by increased numerical aberrations on chromosome arms 1q, 7p, and 8p.

Adenocarcinoma↗
PubMed1999

Finnish norms for the Harvard Group Scale of Hypnotic Susceptibility, Form A.

Finnish norms of the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A) are presented. The aggregate sample of 285 subjects consisted of 3 groups (n = 129, n = 116, and n = 40) that were tested during 1996 and 1997. Comparisons are made with the original normative American sample, an Australian sample, and 3 translated adaptations of HGSHS:A in Danish, German, and Spanish. In the Finnish sample, Items 2 (eye closure), 11 (posthypnotic suggestion), and 12 (amnesia) received high passing percentage in comparison with the reference data, but generally the Finnish normative data were congruent with these index studies.

Adult↗
PubMed1998

Methods for quantitative assessment of airborne levels of noninfectious microorganisms in highly contaminated work environments.

Exposure to high airborne levels of noninfectious microorganisms is recognized as a cause of respiratory symptoms and disease among workers handling biological materials, such as farmers, sawmill workers, and workers handling municipal waste and fuel chips. Risk assessment is difficult because occupational exposure limits for noninfectious microorganisms have not been established. Many different methods are used for the measurement of airborne microorganisms, which are based on impaction, impingement, or filtration. Samples can be analyzed by methods that are culture-based or nonculture-based and that may estimate different microbial entities: culturable microorganisms by culture-based methods, microbial cells by microscopic methods, and microbial constituents and products by chemical, biochemical and immunochemical methods. Sources of errors and validation studies of these methods are reviewed and methods are evaluated for exposure assessment in epidemiological studies and for future compliance testing. At present it is not clear which microbial bioaerosol components should be assessed. Culture-based methods are probably not satisfactory because nonviable microorganisms and microbial constituents and products also may cause health effects. Culture-based methods are poor surrogates for nonculture-based methods and have poor precision. However, identification of microorganisms is most readily performed by culture-based methods. Filter sampling is preferred for personal exposure measurements because filters can be analyzed by a variety of nonculture-based methods, and filter sampling may be adapted to recently adopted criteria for health-related size fractions.

Aerosols↗
PubMed1995

Influence of lasalocid, cationomycin and feeding frequency on the postprandial kinetics of some plasma parameters in the rumen vein, portal vein and mesenteric artery of sheep.

Two adult sheep, A and B, received successively during three experimental periods a forage-based pelleted feed, then the same diet supplemented with 33 mg/kg of lasalocid (L) or cationomycin (C). The feed was given in either eight (sheep A) or two (sheep B) daily meals. After four weeks of adaptation, 11 blood samples were taken through catheters in the rumen vein (RVA) and the mesenteric artery (MAA) in sheep A and in the rumen vein (RVB) and portal vein (PVB) in sheep B over a 5-hour period after the morning meal. Because of a blockage in the catheter it was not possible to measure the effect of C in MAA. Food intake had no immediate effect on the plasma levels measured: the distribution of eight daily meals stabilized plasma levels and made it easier to determine the effect of the ionophores. This effect varied according to the sampling site, the animal and the antibiotic, sometimes contradictorily. All the plasma parameters monitored in RVA were significantly modified by either one of the ionophores. A decrease in plasma albumin concentration (P < 0.05) was observed with L in MAA and with C in RVA and MAA. Aceto-acetate concentration decreased (P < 0.05) with L in MAA but increased with L and C in RVB. A decrease in glycaemia and uraemia (P < 0.05) was observed with L in MAA, RVA and RVB and with C in RVA. Total amino acid concentration decreased (P < 0.05) with C in RVA or increased (P < 0.05) with L in PVB and RVB. These variations in results may be due to different mechanisms of action of L and C on digestion, particularly in the rumen. While the changes undergone by the ketone bodies in the blood suggested a decrease in hepatic ketogenesis with L, there was no evidence that the ionophores had a direct postprandial effect.

Acetoacetates↗
PubMedDate not supplied

Evaluation of the Radiometer Ion Scanning System 820 for the analysis of lead in urine.

We have evaluated the application and performance characteristics of a system that utilizes potentiometric stripping analysis (PSA); an electrochemical technique recently proposed for use in the routine determination of lead in urine. Its advantages over current methods for urinary lead are its low cost and minimal requirements for sample pretreatment. We adapted the published procedure to enable the use of a single protocol over a wide lead concentration range (10-500 microgram/L). Using spiked urine pools, we found the precision and recovery to be acceptable for clinical usage over this range. A comparative study using individual spiked patient urines demonstrated good correlation with a bismuth hydroxide coprecipitation/atomic absorption (AA) procedure [Y (microgram/L, PSA) = -11 microgram/L + 1.10X (microgram/L, AA); S y times x = 32 microgram/L; Sa = 15 microgram/L; Sb = 0.08, N = 22]. Approximately 10% of the randomly chosen urines in this study exhibit negative interferences with the PSA method. However, these interferences were readily recognizable when using a standard addition technique to obtain concentrations from analytical signals, and were resolvable following either dilution with dilute acid or addition of Triton X-100. While we consider the system's performance characteristics acceptable, the length of time required for each urine lead determination (approximately 40 minutes) is a notable limitation to the routine clinical adoption of the instrument in its current configuration.

Electrochemistry↗
PubMed1998

Octamer-primed cycle sequencing using dye-terminator chemistry.

Octamer Sequencing Technology, OST, is a method of DNA sequencing using single octamer oligonucleotides to prime cycle sequencing reactions. This sequencing strategy is faster than a traditional primer-walking strategy, since access to this optimized octamer library eliminates delays associated with designing and synthesizing gene specific primers. In this report, OST has been optimized for fluorescent, dye-terminator cycle sequencing reactions to facilitate parallel processing of samples. The successful adaptation of OST to an automated sequencing platform and the design of and access to an octamer library are critical steps towards developing an efficient 'closed-loop' DNA sequencing system.

Animals↗
PubMed1996

Measurement of airborne 218Po--a Bayesian approach.

The standard mathematical treatment of the buildup and decay of airborne radionuclides on a filter paper uses the solutions of the so-called Bateman equations adapted to the sampling process. These equations can be interpreted as differential equations for the expectation of an underlying stochastic process, which describes the random fluctuations in the accumulation and decay of the sampled radioactive atoms. The process for the buildup and decay of airborne 218Po can be characterized as an "immigration-death process" in the widely adopted, biologically based jargon. The probability distribution for the number of 218Po atoms, accumulated after sampling time t, is Poisson. We show that the distribution of the number of counts, registered by a detector with efficiency epsilon during a counting period T after the end of sampling, is also Poisson, with mean dependent on epsilon, t, T, the flowrate and N(o), the number of airborne 218Po atoms per unit volume. This Poisson distribution was used to construct the likelihood given the observed number of counts. After inversion with Bayes' Theorem we obtained the posterior density for N(o). This density characterizes the remaining uncertainty about the measured number of 218Po atoms per unit volume of air.

Air Pollution, Radioactive↗
PubMed2004

A particle-dynamics study of dissipation in colliding clouds of ultracold fermions.

We present a numerical study of the micro-dynamical roots of dissipation in two colliding mesoscopic clouds of point-like fermions as a function of the scattering length and of temperature approaching full quantum degeneracy. This study, which is motivated by current experiments on ultracold gaseous mixtures of fermionic atoms inside magnetic traps, combines the solution of the coupled Vlasov-Landau equations for the Wigner distribution functions with a locally adaptive importance-sampling technique for handling collisional interactions. The results illustrate the consequences of genuinely quantum collisional phenomena, and in particular the role of Pauli blocking in the transition to hydrodynamic behaviour. We also compare the computed quantum collision rate as a function of temperature in the weak-coupling case with theoretical results assuming that equilibrium distributions determine the quantum collision integral.

Journal Article↗
PubMed1985

Effect of metal-rich sewage sludge application on the bacterial communities of grasslands.

The effect of long-term application of heavy metal-laden sewage sludge on the total heterotrophic aerobic and the cadmium-resistant soil bacterial communities was studied. Gram-positive bacteria were completely absent from resistant communities. These findings suggest that this group is highly susceptible to Cd. Shannon's diversity indices estimated for total communities did not reveal negative effects on the communities that developed in the presence of sludge. However, Cd-resistant communities isolated from long-term sludge-amended soils were more diverse than the resistant communities from a control sample, suggesting that adaptation to Cd as a stressor had occurred in the presence of sludge constituents. This higher diversity was attributed to Cd resistance in pseudomonads and gram-negative fermenters. Resistance did not develop by dissemination of Cd resistance plasmids, because these were rarely detected in the genomes of resistant strains.

Journal Article↗
PubMed1988

A suspension method to determine reuse life of chemical disinfectants during clinical use.

In-use testing of disinfectants is necessary to ensure efficacy over time. The current official procedure for testing disinfectants, the Association of Official Analytical Chemists (AOAC) use-dilution method, cannot be adapted to repeated sampling techniques of use-life testing. It is therefore necessary to use an alternative method when evaluating the activity of a disinfectant under actual use. The Clinical Research Associates (CRA) suspension method was developed to fill this need. It consists of adding 0.5 ml of a standard culture to 5.0 ml of test disinfectant and sampling the mixture after 10 min for surviving bacteria. When this test was compared with the AOAC use-dilution method under a simulated use situation, the two methods were generally equivalent in identifying disinfectant inactivation. In addition, the CRA method was less time consuming, easier to perform, and less variable than the AOAC method. Use of the CRA method in a clinical study demonstrated the need for reuse claims to be based on clinical use studies rather than on laboratory testing only.

Disinfectants↗