bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of sensitivity and specificity of serum poly-C avid ribonuclease activity and C-reactive protein concentration in detection of mild and severe acute pancreatitis
Authors: Kuśnierz-Cabala Beata , Naskalski Jerzy W. , Kędra Boguslaw , Panek Józefa
Published: August 2004

The aim of this study was to compare diagnostic performance of C-reactive protein (CRP) and poly-C avid ribonuclease (P-RNase) levels in the prediction of a severe clinical course of acute pancreatitis (AP). The study included 36 patients with mild and 20 with severe AP. CRP concentration was measured by an immunonephelometric method and P-RNase activity by the rate of polycytidylate hydrolysis at pH 7.8. At the time of admission, both P-RNase and CRP levels were significantly increased in all patients when compared to healthy subjects (29.2 vs. 18.7 U/l and 91.1 vs. 2.89 mg/l; p<0.001). Up to days 3 and 4 a further increase in P-RNase was observed. On the other hand, the increase in CRP continued only through days 2 and 3 (p<0.001). Severe acute pancreatitis (SAP) and mild acute pancreatitis (MAP) differed significantly with respect to P-RNase levels on all days studied; whereas CRP levels differed significantly on days 2–5 but did not differ at admission. Receiver operating characteristic (ROC) curve function analysis yielded the best sensitivity of SAP detection for P-RNase, equaling 72.2%, at the cut-off point value 65.3 U/l on day 3 after admission. The sensitivity of CRP for detection of SAP was 85.0% at 125.7 mg/l on the 2nd day after admission. Both parameters studied were significantly associated with the severity of the AP clinical course; however, on days 1 and 2 postadmission, P-RNase was more specific for detection of SAP than CRP (94.4% vs. 77.1% on the 1st day and 94.4% vs. 55.5% on the 2nd day). In conclusion, P-RNase has shown an excellent performance for early differentiation of acute necrotizing pancreatitis.
Genetic analysis of glutathione S-transferase A1 and T1 polymorphisms in a Japanese population
Authors: Matsuno Kumi , Kubota Takahiro , Matsukura Yuji , Ishikawa Hiroshi , Iga Tatsuji
Published: August 2004

Novel allelic variants have been found in the glutathione S-transferase (
The European Register for Specialists in Clinical Chemistry and Laboratory Medicine: Code ofConduct
Authors: Sanders G. , Opp M. , McMurray J. , Koeller U. , Blaton V. , Lund E. , Harmoinen A. , Zerah S. , Baum H. , Rizos D. , Kenny D. , Pazzagli M. , Hoffman H. , Reguengo H. , Queralt J. M. , Wallinder H. , Jansen R. , Hallworth M. , Schuff-Werner P.
Published: August 2004

The European Communities Confederation of Clinical Chemistry and Laboratory Medicine (EC4) opened a Register for European Specialists in Clinical Chemistry and Laboratory Medicine in 1997. The operation of the Register is undertaken by a Register Committee (EC4RC). During the last 6 years more than 1500 specialists in clinical chemistry and laboratory medicine have joined the Register. In this article a Code of Conduct for Registrants which was approved at the EC4 Register Committee meeting in Amsterdam, 8 November 2003 is presented.
Activity of eosinophils and immunoglobulin E concentration in the peritoneal fluid of women with endometriosis
Authors: Eidukaite Androne , Tamosiunas Vytas
Published: August 2004

Autoinflammatory phenomena, including autoantibody production and atopy, have been regarded as associated with endometriosis. The present study investigates the activity of eosinophils and the distribution of immunoglobulin E concentrations in the peritoneal fluid of women with early endometriosis. The study group consisted of 30 patients with laparoscopically diagnosed early endometriosis. The healthy control group consisted of 18 females with no evident changes in the abdominal cavity and no endometrial foci. Concentrations of immunoglobulin E in serum and peritoneal blood were determined by enzyme immunoassay. The activity of eosinophils was estimated according to the expression of the early activation molecule CD69 by the flow cytometry method. The concentrations of immunoglobulin E in the peripheral blood and peritoneal fluid were similar in both groups. However, the count of CD69+ eosinophils was higher in the peritoneal fluid of women with endometriosis. The results indicate that activated eosinophils accumulate in the peritoneal fluid in early endometriosis and can play a significant role in the pathogenesis of the disease.
Presence of secretory group IIa and V phospholipase A2 and cytosolic group IVα phospholipase A2 in chondrocytes from patients with rheumatoid arthritis
Authors: Leistad Lilian , Feuerherm Astrid J. , Østensen Monika , Faxvaag Arild , Johansen Berit
Published: August 2004

Both secretory and cytosolic phospholipase A
Neurokinin B levels in maternal circulation during early pregnancy
Authors: Tjoa May Lee , Lomecky Marie , Martens Frans , Wijk Inge J. van , Vugt John M. G. van , Blankenstein Marinus A. , Oudejans Cees B. M.
Published: August 2004

Neurokinin B levels were measured between the 10th–20th weeks of pregnancy, i.e., prior to the development of clinical symptoms, in women who developed preeclampsia or delivered a growth-restricted baby. No difference was found in plasma neurokinin B levels, although neurokinin B levels increased slightly towards term.
Cl- regulates cryoglobulin structure: a new hypothesis for the physiopathological mechanism of temperature non-dependent cryoprecipitation
Authors: Stasio Enrico Di , Bizzarri Patrizia , Casato Milvia , Galtieri Antonio , Fiorilli Massimo , Pucillo Leopoldo Paolo
Published: August 2004

Cryoglobulins are pathological cold-precipitable immunoglobulins associated with a number of infectious, autoimmune and neoplastic disorders. Patients, when exposed to low temperatures, show symptoms related to intravascular precipitation of such immunoglobulins. The formation of cryoaggregates induced by exposure to cold temperature is the key pathogenetic mechanism. The subsequent intravascular precipitation can account for some clinical signs of peripheral vasculitis, but fails to explain the precipitation of cryoglobulins in regions where no significant temperature changes take place. We studied, in vitro, the activity of different ions on temperature-dependent aggregation of cryoglobulins and found that the concentration of Cl
Comparison of serum creatinine, uric acid, albumin and glucose in male professional endurance athletes compared with healthy controls
Authors: Lippi Giuseppe , Brocco Giorgio , Franchini Massimo , Schena Federico , Guidi Giancesare
Published: August 2004

Owing to considerable physical, endocrinological and metabolic adaptations, the analysis of biochemical data in elite and top-class athletes requires caution. With the aim to identify metabolic and biochemical adaptations to particular lifestyle conditions, such as regular and strenuous physical exercise, we measured the concentration of serum albumin, creatinine, uric acid and glucose in 80 male professional cyclists, 37 male members of the Italian national cross-country ski team and 60 male healthy sedentary controls at rest. At variance with earlier investigations, endurance athletes showed significantly decreased concentrations of serum creatinine (controls: 83.1±11.0 μmol/l; skiers: 78.0±8.4 μmol/l; p<0.05; cyclists: 73.8±10.4 μmol/l; p<0.01), uric acid (controls: 362±69 μmol/l; skiers: 331±70 μmol/l; p<0.05; cyclists: 312±61 μmol/l; p<0.01) and glucose (controls: 5.35±0.54 mmol/l; skiers: 4.94±0.41 mmol/l; p<0.01; cyclists: 4.94±0.42 mmol/l; p<0.01). The concentration of serum albumin was also decreased in athletes, but the difference did not reach statistical significance (controls: 4.76±0.26 g/l; skiers: 4.71±0.22 g/l; p=0.384; cyclists: 4.68±0.22 g/l; p=0.393). Results of the present investigation demonstrate that values of laboratorytesting lying outside conventional reference limits calculated on sedentary populations might express physiological adaptations to regular and demanding physical aerobic activity, emphasizing the need for the estimation of reliable reference limits in elite and professional athletes, to avoid equivocal interpretation of results within clinical and anti-doping contests.
Low S-adenosylmethionine concentrations found in patients with severe inflammatory bowel disease
Authors: Schmedes Anne , Nielsen Jens Nederby , Hey Henrik , Brandslund Ivan
Published: August 2004

Background: S-adenosylmethionine is a methyl donor in many cellular reactions including detoxification of constantly produced hydrogen sulphide in the colon. A reduced capacity to detoxify hydrogen sulphide may be implicated in the pathogenesis of inflammatory bowel disease. S-adenosylmethionine could be low if this assumption is correct. We compared S-adenosylmethionine concentrations in whole blood in patients with severe and moderate inflammatory bowel disease with healthy reference persons. Methods: S-adenosylmethionine concentrations in whole blood were measured using high-pressure liquid chromatography. Patients with Crohn's disease (n=21), ulcerative colitis (n=7) and healthy age-matched reference persons (or controls) (n=17) were studied. Results: S-adenosylmethionine concentrations were significantly decreased in patients with severe inflammatory bowel disease (mean 1.10 mg/l) as compared to patients with moderate Crohn's disease and ulcerative colitis (mean 1.83 mg/l) and reference persons (mean 1.84 mg/l). Statistically significant inverse correlations were found between S-adenosylmethionine concentration and activity index (p<0.01 and R
The influence of freezer storage of urine samples on the BONN-Risk-Index for calcium oxalate crystallization
Authors: Laube Norbert , Zimmermann Diana J.
Published: August 2004

This study was performed to quantify the effect of a 1-weekfreezer storage of urine on its calcium oxalate crystallization risk. Calcium oxalate is the most common urinary stone material observed in urolithiasis patients in western and affluent countries. The BONN-Risk-Index of calcium oxalate crystallization risk in human urine is determined from a crystallization experiment performed on untreated native urine samples.

We tested the influence of a 1-weekfreezing on the BONN-Risk-Index value as well as the effect of the sample freezing on the urinary osmolality. In vitro crystallization experiments in 49 native urine samples from stone-forming and non-stone forming individuals were performed in order to determine their calcium oxalate crystallization risk according to the BONN-Risk-Index approach. Comparison of the results derived from original sample investigations with those obtained from the thawed aliquots by statistical evaluation shows that i) no significant deviation from linearity between both results exists and ii) both results are identical by statistical means. This is valid for both, the BONN-Risk-Index and the osmolality data.

The differences in the BONN-Risk-Index results of both procedures of BONN-Risk-Index determination, however, exceed the clinically acceptable difference. Thus, determination of the urinary calcium oxalate crystallization risk from thawed urine samples cannot be recommended.
The evolution of the reference value concept
Authors: Gräsbeck Ralph
Published: August 2004

This manuscript reviews the introduction of the concept of reference values, the corresponding philosophy, and subsequent recommendations reflecting the different subtopics of the field. The generally unrecognised phenomenon that laboratory results of the population tended to be lognormal instead of Gaussian attracted the attention of the author, who became sceptical of the concept of normal values because of its ambiguity. Together with N.-E. Saris a new concept of reference values was launched at a congress in 1969. Briefly, clinical measurements should be interpreted against values from proper control subjects. Subsequently international, regional and national societies established expert panels which produced recommendations covering the general principles and terminology of reference values, the concept of health, standardised specimen collection and preanalytical factors, statistical treatment of collected values, stratification of data, relating observed (patient) values to reference values, etc. The importance of using correct terminology, taking into consideration the aim of ordering the laboratory test and some neglected procedures (e.g., survival values) are emphasised. New developments such as reference changes are mentioned. The field has evolved largely as the result of constructive international teamwork.
Graphical interpretation of confidence curves in rankit plots
Authors: Petersen Per Hyltoft , Blaabjerg Ole , Andersen Marianne , Jørgensen Lone G. M. , Schousboe Karoline , Jensen Esther
Published: August 2004

A well-known transformation from the bell-shaped Gaussian (normal) curve to a straight line in the rankit plot is investigated, and a tool for evaluation of the distribution of reference groups is presented. It is based on the confidence intervals for percentiles of the calculated Gaussian distribution and the percentage of cumulative points exceeding these limits.

The process is to rank the reference values and plot the cumulative frequency points in a rankit plot with a logarithmic (ln=log

This is a conservative validation, which is more demanding than the Kolmogorov-Smirnov test. The graphical presentation, however, makes it easy to disclose deviations from ln-Gaussianity, and to make other interpretations of the distributions, e.g., comparison to non-Gaussian distributions in the same plot, where the cumulative frequency percentage can be read from the ordinate. A long list of examples of ln-Gaussian distributions of subgroups of reference values from healthy individuals is presented. In addition, distributions of values from well-defined diseased individuals may showup as ln-Gaussian.

It is evident from the examples that the rankit transformation and simple graphical evaluation for non-Gaussianity is a useful tool for the description of sub-groups.
Partitioning biochemical reference data intosubgroups: comparison of existing methods
Authors: Lahti Ari
Published: August 2004

Four existing methods for partitioning biochemical reference data into subgroups are compared. Two of these, the method of Sinton et al. and that of Ichihara and Kawai, are based on a quotient of a difference between the subgroups and the reference interval for the combined distribution. The criterion of Sinton et al. appears rather stringent and could lead to recommendations to apply a common reference interval in many cases where establishment of group-specific reference intervals would be more useful. The method of Ichihara and Kawai is similar to that of Sinton et al., but their criterion, based on a quantity derived from between-group and within-group variances, seems to lead to inconsistent results when applied to some model cases. These two methods have the common weakness of using gross differences between subgroup distributions as an indicator of differences between their reference limits, while distributions with different means can actually have equal reference limits and those with equal means can have different reference limits. The idea of Harris and Boyd to require that the proportions of the subgroup distributions outside the common reference limits be kept reasonably close to the ideal value of 2.5% as a prerequisite for using common reference limits seems to have been a major improvement. The other two methods considered, that of Harris and Boyd and the “new method” follow this idea. The partitioning criteria of Harris and Boyd have previously been shown to provide a poor correlation to those proportions, however, and the weaknesses of their method are summarized in a list of five drawbacks. Different versions of the new method offer improvements to these drawbacks.
Should we maintain the 95 percent reference intervals in the era of wellness testing? A concept paper
Authors: Jørgensen Lone G. M. , Brandslund Ivan , Petersen Per Hyltoft
Published: August 2004

The reference interval is probably the most widely used decision-making tool in clinical practice, with a modern use aiming at identifying wellness during health check and screening. Its use as a diagnostic tool is much less recognised and may be obsolete.

The present study investigates the consequences of the newpractice for the interpretation of prospective value, negative vs. positive, the probability of confirming wellness, and number of false results based on selected strategy for reference interval establishment.

Calculations assumed normalised Gaussian-distributed reference intervals with analytical variation set to zero and absolute accuracy. Also assumed is the independency of tests. Probability for no values outside reference intervals in healthy subjects was calculated from the formula p

Use of the 99.9 centile for health checks will increase the probability for no false from 60% to 99% for 10 tests, and from 46% to 98% for 15 tests.

The probability for one false-positive result in 10 tests in a panel can be reduced from 32% to 1% if the 99.9% centile is substituted for the 95% centile. For two in 10 tests, the probability can be reduced from 8% to below 0.1%. In both cases, selection of the 99.9% centile improves the diagnostic accuracy.

Reference intervals are needed as a “true” negative reference for absence of disease, and should cover the 99.9% centile of the reference distribution of an analyte to avoid false positives. For this new use, it is critical that reference persons are absolutely normal without clinical, genetic and biochemical signs of the condition being investigated. However, reference intervals cannot substitute clinical decision limits for diagnosis and medical intervention.
Clinical interpretation of reference intervals and reference limits. A plea for assay harmonization
Authors: Klee George G.
Published: August 2004

Reference intervals for healthy subjects and diseased populations are important benchmarks for the clinical interpretation of laboratory test values. It is important that the testing conditions used to collect the reference data be closely matched with the testing conditions used for patient data. Interlaboratory differences and intralaboratory changes, especially changes in analytic set-points, can markedly affect the clinical interpretation of tests. If laboratory testing methods could be harmonized, laboratories could potentially share reference data to make these data more reliable.

This chapter illustrates the use of reference intervals for healthy subjects and reference data from diseased populations for medical decisions. One example illustrates the effects of age differences on test result interpretation. Other examples illustrate use of thyroid-stimulating hormone (TSH) and combinations of TSH with free thyroxine measurements for diagnosing thyroid diseases. Both univariate and multivariate reference intervals are discussed. Model systems for using disease prevalence and cost utility functions are provided to illustrate optimization of medical decisions.
Inherent biological variation and reference values
Authors: Fraser Callum G.
Published: August 2004

There is a need for revisiting theoretical concepts and practical applications of conventional population-based reference values to make for better clinical use of laboratory data. Knowledge of the underlying biological variation of quantities examined in medical laboratories is vital to understanding the proper generation and application of traditional population-based reference values. Appreciation of the biological changes that occur over the span of life is a necessary prerequisite to deciding whether stratification of reference values according to age is likely to be necessary. Knowledge of the detail of predictable biological cyclical rhythms is required for correct clinical interpretation of laboratory data and appropriate collection of specimens at times relevant to the clinical purpose. Quantitative data on inherent within- and between-subject biological components of variation have shown the marked individuality of most quantities of interest in laboratory medicine. This individuality casts light on why examinations are not generally very successfully applied in population screening or case-finding. Consideration of individuality demonstrates why stratification of reference values is often very advantageous. Individuality provides an indisputable argument for better use of individual specific reference values.
Intraindividual reference values
Authors: Queraltó Josep M.
Published: August 2004

When a biological quantity examination exhibits a high degree of individuality, developing a strategy for interpreting these values in an individual context can be a useful alternative. Time-series analysis is the appropriate statistical framework to build a model for explanation of the behaviour of laboratory information and to forecast future values. The key concepts in this approach are autocorrelation and withinperson variance. Unfortunately, the powerful tools provided by time-series analysis require many observations, a requisite difficult to meet in every day practice. However, introducing some restrictions in the autocorrelation parameter of the most reliable model, the first order autocorrelation model, and using the average within-person variance from a selected population, it is possible to build predictive reference intervals for an individual, based on only few observations. The most common case is the minimum time series: when there are just two observations. The statistical significance of the change from a previous observation is a problem that arises from both quality control (delta checks) and the interpretative diagnostic fields (reference change limit). Applying the same restrictive criteria, it is possible to develop specific limits for a difference between consecutive observations based on a within-person variance selected from the distribution of variances found in a sample of similar individuals.
Proposal for guidelines to establish common biological reference intervals in large geographical areas for biochemical quantities measured frequently in serum and plasma
Authors: Rustad Pål , Felding Peter , Lahti Ari
Published: August 2004

A suggestion for a standard procedure to establish biological reference intervals for biochemical quantities by a multicenter approach is presented. This procedure was developed for and used in the Nordic Reference Interval Project 2000 (NORIP). This project established biological reference intervals for 25 frequently requested biochemical quantities through cooperation of 102 Nordic laboratories. Each laboratory performed collection of reference samples and measurement using their routine methods. The bias of each routine method was eliminated by use of common reference materials measured in each of the participating laboratories.
Study of reference values and biological variation: a necessity and a model for Preventive Medicine Centers
Authors: Siest Gérard
Published: August 2004

Laboratory tests were at the origin of the modern approach to the evaluation of the health status in many Preventive Medicine Centers.

Guided by the theory of reference values and its applications, years of efforts have been devoted to defining the health status of people, and understanding the biological variation of the population.

At the Nancy Center for Preventive Medicine, 40,000 people are invited every year for health examination; many coming with their families. French legislation authorized every citizen to have full health examination every five years. Annually, 600,000 people are seen at 70 centers.

The visit includes answering questionnaires, physiological and biological testing modified for age, risks, and social criteria. The process concludes with consultation with a general practitioner.

Data accumulated over 30 years have led to the identification of primary factors influencing biological variation of common laboratory tests. For example, body mass index (BMI) has to be considered, in addition to age and gender, for measurement of γ-glutamyltransferase, alanine aminotransferase, and other analytes.

More recently, the familial Stanislas cohort has shown that apolipoprotein E (apoE) genetic polymorphism has to be considered as a factor for variation in some individuals. For example, there was greater than 100% difference in the mean concentration of apoE between
Difficulties in establishing reference intervals for special fluids: the example of 5-hydroxyindoleacetic acid and homovanillic acid in cerebrospinal fluids
Authors: Dhondt Jean-Louis
Published: August 2004

Biochemical measurements in “special fluids” are complicated with the problem of reference intervals. Reference intervals are difficult to establish for these types of samples since they are usually only collected in patients with clinical suspicion of disease. Determination of neurotransmitter metabolites in cerebrospinal fluid illustrates this difficulty. This paper will review the factors and circumstances that have been identified or are suspected to modifythe concentration of 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) in cerebrospinal fluid. In addition to obvious parameters such as age-related variation that can affect the concentration of 5-HIAA and HVA in cerebrospinal fluid, a varietyof other factors can explain the wide range of “control” group sizes reported in the literature. Reference intervals must take into account the purpose of cerebrospinal fluid examinations, whether they be prospective studies to explore physio-pathologic relationships or for diagnostic purposes. In the latter case, certain neurological disorders cannot be excluded if a single measured value is within the reference interval.
Creation of the necessary analytical quality for generating and using reference intervals
Authors: Klein Gerhard , Junge Wolfgang
Published: August 2004

This is a brief compilation of criteria on analytical quality that are prerequisites for the establishment and use of reference intervals in laboratory medicine. In this context, analytical quality is characterized by the precision, accuracy and long-term stability of laboratory methods performed with diagnostic kits, including their application on various instrument platforms. Systematically, analytical quality can be differentiated into quality of the method and its performance, and quality of long-term use. Factors influencing these types of quality in the development of diagnostic kits are discussed. The responsibility for maintaining analytical quality is shared by the two parties involved in the provision and use of reference intervals: The manufacturers of diagnostic kits are committed to providing complete description and traceability of their methods, whereas users must consider the effects of physiological, biometrical, preanalytical and analytical influences on the reference interval.
Analytical quality specifications for common reference intervals
Authors: Ricós Carmen , Doménech Maria Vicenta , Perich Carmen
Published: August 2004

Interpretation oflaboratory test results requires comparison to some type of reference value or reference interval. These comparisons can be cross-sectional (population-based reference interval and cut-off values) or longitudinal (reference change value). Quality specifications for cross-sectional comparison have been established by determining the influence of analytical bias and imprecision on the percentage ofthe healthy population falling outside the reference limits, when sharing population-based reference intervals in a Gaussian distribution ofresults. Quality specifications for longitudinal comparisons are equally important and are often overlooked, since less work has been done in this area. Some criteria suggest that a difference between consecutive results designates a true change in a patient health status when the difference is higher than the within-subject biological variation plus the within-laboratory analytical variation. In this chapter we discuss the clinical considerations and laboratory-related factors that must be considered when quality specifications are applied to sharing reference comparisons. Real life experience shows that different analytical methods can produce comparable results when common quality goals are established, and quality can be achieved through a willingness to work together. Within the existing organization, the current specifications for analytical quality and a dedication to quality health care makes it possible to achieve transferability between laboratories within a geographic area.
Design of internal quality control for reference value studies
Authors: Westgard James O.
Published: August 2004

Internal quality control should assure that the desired quality goals are achieved during reference value studies. Quality goals are often stated in the form of allowable limits of error, such as an allowable total error or an allowable bias. For reference value studies, it may be more appropriate to utilize a goal for allowable bias. In either case, it is possible to calculate a metric in the form of the critical systematic error that can be used to guide selection or design of the internal quality control procedure. A graphical tool, called the critical-error graph, facilitates the selection by superimposing the calculated critical systematic error on the power curves of different control rules and numbers of control measurements. Examples are provided to illustrate the calculation of the critical systematic error from both an allowable total error goal and an allowable bias goal, using figures from an extensive tabulation of available total error and bias goals.
Learning Enhances the Survival of New Neurons beyond the Time when the Hippocampus Is Required for Memory
Authors: Leuner Bendetta , Mendolia-Loffredo Sabrina , Kozorovitskiy Yevgenia , Samburg Deanna , Gould Elizabeth , Shors Tracey J.
Published: August 2004

Trace memories are formed when a stimulus event becomes associated with another event that occurs later in time and is discontinuous with the first event. The formation of trace memories enhances the survival of newly generated neurons in the dentate gyrus of the adult hippocampus (Gould et al., 1999a). Here we tested whether the acquisition of trace memories early during training is sufficient to enhance cell survival. We also examined whether the new neurons affected by trace memory formation persist indefinitely or only as long as the hippocampus is necessary for the expression of those memories. Groups of adult rats were injected with bromodeoxyuridine (BrdU), a marker of dividing cells, and trained 1 week later with paired stimuli using a trace eyeblink conditioning task or exposed to the same number of unpaired stimuli. Cell survival was assessed after different numbers of training trials and survival periods after training. Overall cell survival was not enhanced by exposure to 200 trials of paired stimuli during trace conditioning. However, there was a positive correlation between performance of individual animals and cell survival. In addition, exposure to 800 trials of paired stimuli during trace conditioning increased the number of BrdU-labeled cells 60 d after training. The vast majority of these cells were neurons and coexpressed the neuronal markers class IIIβ-tubulin or neuronal nuclei. These data suggest that individual differences in associative learning predict whether new neurons will survive and that once affected, these neurons remain for months and beyond the time when they are required for the retention of trace memories.
Input-Driven Components of Spike-Frequency Adaptation Can Be UnmaskedIn Vivo
Authors: Gollisch Tim , Herz Andreas V. M.
Published: August 2004

Spike-frequency adaptation affects the response characteristics of many sensory neurons, and different biophysical processes contribute to this phenomenon. Many cellular mechanisms underlying adaptation are triggered by the spike output of the neuron in a feedback manner (e.g., specific potassium currents that are primarily activated by the spiking activity). In contrast, other components of adaptation may be caused by, in a feedforward way, the sensory or synaptic input, which the neuron receives. Examples include viscoelasticity of mechanoreceptors, transducer adaptation in hair cells, and short-term synaptic depression. For a functional characterization of spike-frequency adaptation, it is essential to understand the dependence of adaptation on the input and output of the neuron. Here, we demonstrate how an input-driven component of adaptation can be uncoveredin vivofrom recordings of spike trains in an insect auditory receptor neuron, even if the total adaptation is dominated by output-driven components. Our method is based on the identification of different inputs that yield the same output and sudden switches between these inputs. In particular, we determined for different sound frequencies those intensities that are required to yield a predefined steady-state firing rate of the neuron. We then found that switching between these sound frequencies causes transient deviations of the firing rate. These firing-rate deflections are evidence of input-driven adaptation and can be used to quantify how this adaptation component affects the neural activity. Based on previous knowledge of the processes in auditory transduction, we conclude that for the investigated auditory receptor neurons, this adaptation phenomenon is of mechanical origin.
Tonotopic Gradients of Membrane and Synaptic Properties for Neurons of the Chicken Nucleus Magnocellularis
Authors: Fukui Iwao , Ohmori Harunori
Published: August 2004

Nucleus magnocellularis (NM) is a division of the avian cochlear nucleus that extracts the timing of auditory signals. We compared the membrane excitability and synaptic transmission along the tonotopic axis of NM. Neurons expressed a Kv1.1 potassium channel mRNA and protein predominantly in the high characteristic frequency (CF) region of NM. In contrast, the expression of Kv1.2 mRNA did not change tonotopically. Neurons also showed tonotopic gradients in resting potential, spike threshold, amplitude, and membrane rectification. All neurons were sensitive to 100 nmdendrotoxin, but the effects were most significant in the high CF neurons. The EPSC recorded by minimal stimulation of auditory nerve fibers (ANFs) was 13 times larger in high CF neurons than in low CF neurons. Moreover, EPSCs were generated in an all-or-none manner in the high CF neurons when stimulus intensity was increased, whereas EPSCs were graded in the low CF neurons, indicating multiple axonal inputs. ANF synaptic terminals were visualized by DiI. ANF formed enfolding end-bulbs of Held around the cell body in the high and middle CF region but not in the low CF region. These observations indicate coordinated gradients of neuronal properties both presynaptically and postsynaptically along the tonotopic axis. Such specializations may be suitable for extracting and preserving the timing information of auditory signals over a wide range of acoustic frequencies.
L-Type Ca2+Channels Mediate Adaptation of Extracellular Signal-Regulated Kinase 1/2 Phosphorylation in the Ventral Tegmental Area after Chronic Amphetamine Treatment
Authors: Rajadhyaksha Anjali , Husson Isabelle , Satpute Shirish S. , Küppenbender Karsten D. , Ren J. Q. , Guerriero Rejean M. , Standaert David G. , Kosofsky Barry E.
Published: August 2004

L-type Ca2+channels (LTCCs) play an important role in chronic psychostimulant-induced behaviors. However, the Ca2+second messenger pathways activated by LTCCs after acute and recurrent psychostimulant administration that contribute to drug-induced molecular adaptations are poorly understood. Using a chronic amphetamine treatment paradigm in rats, we have examined the role of LTCCs in activating the mitogen-activated protein (MAP) kinase pathway in the ventral tegmental area (VTA), a primary target for the reinforcing properties of psychostimulants. Using immunoblot and immunohistochemical analyses, we find that in chronic saline-treated rats a challenge injection of amphetamine increases phosphorylation of MAP [extracellular signal-regulated kinase 1/2 (ERK1/2)] kinase in the VTA that is independent of LTCCs. However, in chronic amphetamine-treated rats there is no increase in amphetamine-mediated ERK1/2 phosphorylation unless LTCCs are blocked, in which case there is robust phosphorylation in VTA dopamine neurons. Examination of the expression of phosphatases reveals an increase in calcineurin [protein phosphatase 2B (PP2B)] and MAP kinase phosphatase-1 (MKP-1) in the VTA. Usingin situhybridization histochemistry and immunoblot analyses, we further examined the mRNA and protein expression of the LTCC subtypes Cav1.2 and Cav1.3 in VTA dopamine neurons in drug-naive animals and in rats after chronic amphetamine treatment. We found an increase in Cav1.2 mRNA and protein levels, with no change in Cav1.3. Together, our results suggest that one aspect of LTCC-induced changes in second messenger pathways after chronic amphetamine exposure involves activation of the MAP kinase phosphatase pathway by upregulation of Cav1.2 in VTA dopaminergic neurons.
AMPA Receptor Synaptic Targeting Regulated by Stargazin Interactions with the Golgi-Resident PDZ Protein nPIST
Authors: Cuadra Adolfo E. , Kuo Sheng-Han , Kawasaki Yoshimi , Bredt David S. , Chetkovich Dane M.
Published: August 2004

Regulation of AMPA receptors (AMPARs) at synapses plays a critical role in alterations of synaptic strength in the brain. Stargazin, an AMPAR-interacting protein, is critical for clustering and regulation of synaptic AMPARs. Stargazin interacts with AMPARs via its extracellular domain and with PDZ [postsynaptic density-95 (PSD-95)/Discs large (Dlg)/zona occludens-1 (ZO-1)] proteins via its C-terminal PDZ-binding motif, and these interactions are necessary for stargazin and AMPAR synaptic targeting. By studying the expression of stargazin mutant constructs in cultured hippocampal neurons, we identified a novel domain corresponding to residues 243-283 within the cytoplasmic C terminus of stargazin that is also required for stargazin and AMPAR synaptic clustering. To identify proteins that interact with this stargazin synaptic clustering domain, we performed a yeast two-hybrid assay and found that this stargazin domain binds to nPIST (neuronal isoform of protein-interacting specifically with TC10), a Golgi-enriched protein implicated in trafficking of transmembrane proteins. Usingin situhybridization, immunohistochemistry, coimmunoprecipitation studies, and biochemical fractionation, we found that stargazin and nPIST colocalize and interact in the brain. Finally, by studying AMPAR clustering in transfected hippocampal neurons, we found that overexpression of nPIST enhances AMPAR synaptic clustering, whereas transfection of a dominant-negative nPIST construct attenuates AMPAR synaptic clustering. These studies identify a novel stargazin domain necessary for synaptic clustering of AMPARs and suggest that nPIST and stargazin interactions play a critical role in AMPAR trafficking to the synapse.
Asymmetrical Neural Substrates of Tactile Discrimination in Humans: A Functional Magnetic Resonance Imaging Study
Authors: Harada Tokiko , Saito Daisuke N. , Kashikura Ken-Ichi , Sato Tetsuhiro , Yonekura Yoshiharu , Honda Manabu , Sadato Norihiro
Published: August 2004

The left-hand advantage seen during tactile discrimination tasks suggests hemispheric-processing asymmetry, although its neural substrates are not well known. We used functional magnetic resonance imaging to evaluate the laterality of the neural substrates involved in tactile discrimination in 19 normal volunteers. Passive tactile discrimination tasks, along with appropriate control tasks, were performed with both the right and left hands to evaluate the effects of the hand used and hemispheric effects (i.e., laterality of the activation pattern). Regardless of the hand used, the right dorsolateral prefrontal cortex, posterior parietal cortex, pre-supplementary motor area, and rostral portion of the dorsal premotor cortex (PMdr) were activated asymmetrically during tactile discrimination. This confirms the previous finding of a right-sided asymmetry for tactile shape discrimination. Hand effects were found in the left caudal portion of PMd (PMdc) adjacent to the central sulcus, which showed prominent activation during right-handed but not left-handed discrimination tasks. This asymmetric activation in the left PMdc might be related to the asymmetric interhemispheric interaction during right-handed tactile discrimination.
Activation and Habituation of Extracellular Signal-Regulated Kinase Phosphorylation in Zebra Finch Auditory Forebrain during Song Presentation
Authors: Cheng Hui-Yun , Clayton David F.
Published: August 2004

The sound of tape-recorded birdsong triggers a set of behavioral and physiological responses in zebra finches, including transcriptional activation of thezenkgene in the auditory forebrain. Song repetition leads to the stimulus-specific habituation of these responses. To gain insight into the mechanisms that couple auditory experience to gene regulation, we monitored the phosphorylation of the zebra finch extracellular signal-regulated kinase (ERK) protein by immunoblotting. Initial presentations of novel song (but not tones or noise) resulted in a rapid increase in ERK phosphorylation, followed by a return to basal levels within 5 min. This response was localized to the auditory forebrain where thezenkgene is activated. Sustained repetition of one song caused a selective habituation of the ERK response: a different song triggered another cycle of ERK phosphorylation without altering the habituated response to the first. To test directly for a role of ERK in experience-dependentzenkgene regulation, we infused an inhibitor of mitogen-activated and extracellular-regulated protein kinase kinase (MEK-1; the enzyme responsible for ERK activation) unilaterally into one auditory lobule just before song stimulation. The song-induced increase inzenkmRNA was blocked on the side of the injection, but not on the contralateral (uninfused) side. These results show that ERK phosphorylation is necessary for the initiation of thezenkgene response to novel song and identify ERK as a plausible site of signal integration underlying the selective habituation of genomic responses to a repeated song.
Orexin-A Infusion in the Locus Ceruleus Triggers Norepinephrine (NE) Release and NE-Induced Long-Term Potentiation in the Dentate Gyrus
Authors: Walling Susan G. , Nutt David J. , Lalies Margaret D. , Harley Carolyn W.
Published: August 2004

The orexins (ORX-A/ORX-B) are neuroactive peptides known to have roles in feeding and sleep. Evidence of dense, excitatory projections of ORX-A neurons to the noradrenergic pontine nucleus, the locus ceruleus (LC), suggests ORX-A also participates in attention and memory. Activation of LC neurons by glutamate produces a β-adrenergic receptor-mediated long-term potentiation (LTP) of the perforant path-evoked potential in the dentate gyrus, a target structure of the LC that has been implicated in memory. We asked whether ORX-A also activates norepinephrine (NE)-induced LTP by initiating NE release in the hippocampus. Here, we show that ORX-A infusion (0.25-25 fmol) into the LC produces a robust, β-adrenergic receptor-dependent, long-lasting potentiation of the perforant path-evoked dentate gyrus population spike in the anesthetized rat. Pharmacological inactivation of the LC with an α2-adrenergic receptor agonist, before ORX-A infusion, prevents this potentiation. Analysis of NE concentrations in the hippocampus after ORX-A infusion into the LC reveals a transient, but robust, increase in NE release. Thus, this study demonstrates that the dense orexinergic projection to the LC promotes the induction of NE-LTP in the dentate gyrus. ORX-A modulation of LC activity may provide important support for the cognitive processes of attention and memory.
Mate Searching inCaenorhabditis elegans: A Genetic Model for Sex Drive in a Simple Invertebrate
Authors: Lipton Jonathan , Kleemann Gunnar , Ghosh Rajarshi , Lints Robyn , Emmons Scott W.
Published: August 2004

Much of animal behavior is regulated to accomplish goals necessary for survival and reproduction. Little is known about the underlying motivational or drive states that are postulated to mediate such goal-directed behaviors. Here, we describe a mate-searching behavior of theCaenorhabditis elegansmale that resembles the motivated behaviors of vertebrates. AdultC. elegansmales, if isolated from mating partners, will leave the area of a food source and wander about their environment in an apparent search for a mate. When mating partners are present on the food source, males do not wander but remain with them. This behavior is sexually dimorphic forC. elegansand two additional male/hermaphrodite species studied; for these species, hermaphrodites leave food significantly slower than males. In contrast, for three male-female species examined, both males and females left food, in two cases with similar frequency, suggesting coordinate evolution of behavioral dimorphism with hermaphroditism. We use a quantitative behavioral assay to show thatC. elegansmale mate searching is regulated by signals from hermaphrodites and by physiological signals indicating nutritional and reproductive status. We identify genes in the serotonin, insulin, and sex determination pathways that affect the rate of mate searching. These genes may contribute to physiological and reproductive regulatory mechanisms. Our results establishC. elegansas a model genetic animal with a simple nervous system in which neural pathways leading to a motivated behavior may be genetically dissected.
Recruitment of the Rod Pathway by Cones in the Absence of Rods
Authors: Strettoi Enrica , Mears Alan J. , Swaroop Anand
Published: August 2004

In mammalian retinas, rods and cones connect to distinct sets of bipolar cells. In the retina of Nrl (neural retina leucine zipper) knock-out mice, in which rods fail to form and all photoreceptors are cones, rod bipolar cells have normal morphology, pattern of staining, and lamination, but they form synaptic connections with cones. Hence, retinal interneurons are not entirely committed to the choice of their synaptic partners; also, their morphology and pattern of distribution of their processes in the synaptic layers of the retina are not instructed by the establishment of synaptic connections with cognate photoreceptor(s). These findings are of considerable relevance for our understanding of mechanisms responsible for cell recognition during development and in the context of using transplanted tissue to restore vision in retinal degeneration.
Dysregulation of Gene Expression in the 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine-Lesioned Mouse Substantia Nigra
Authors: Miller Renee M. , Callahan Linda M. , Casaceli Cindy , Chen Linlin , Kiser Gretchen L. , Chui Buena , Kaysser-Kranich Tamma M. , Sendera Timothy J. , Palaniappan Chockalingam , Federoff Howard J.
Published: August 2004

Parkinson's disease pathogenesis proceeds through several phases, culminating in the loss of dopaminergic neurons of the substantia nigra (SN). Although the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of oxidative SN injury is frequently used to study degeneration of dopaminergic neurons in mice and non-human primates, an understanding of the temporal sequence of molecular events from inhibition of mitochondrial complex 1 to neuronal cell death is limited. Here, microarray analysis and integrative data mining were used to uncover pathways implicated in the progression of changes in dopaminergic neurons after MPTP administration. This approach enabled the identification of small, yet consistently significant, changes in gene expression within the SN of MPTP-treated animals. Such an analysis disclosed dysregulation of genes in three main areas related to neuronal function: cytoskeletal stability and maintenance, synaptic integrity, and cell cycle and apoptosis. The discovery and validation of these alterations provide molecular evidence for an evolving cascade of injury, dysfunction, and cell death.