Post-traumatic stress disorder and amygdala-hippocampectomy

OBJECTIVE

The case report suggests the indispensability of preoperative accurate psychiatric checkups especially in temporal resections.

METHOD

A single case was reported.

RESULTS

We report the case of a 20-year-old woman suffering for 12 years from primary generalized epilepsy, attributed to left-sided hippocampal sclerosis. Because seizures were resistant to drug therapy, she underwent amygdala-hippocampectomy at the age of 18. Furthermore, she had previously been victim of childhood sexual abuse. Two weeks after epilepsy surgery, she manifested symptoms of post-traumatic stress disorder (PTSD).

CONCLUSION

There is evidence that the amygdala-hippocampal region is both functionally and morphologically involved in the aetiology of PTSD. The removal of this marked neuroanatomical region and the resulting disconnection and asymmetry between right and left amygdala-hippocampal region might be seen as an evidence for this region aetiologically being involved in the patient's PTSD symptoms.

Effect of nebulized albuterol on blood glucose in patients with diabetes mellitus with and without cystic fibrosis

Over 90% of cystic fibrosis (CF) patients are treated with bronchodilators, and 6% have diabetes. Some with asthma also have diabetes, and most are treated with bronchodilators. Systemic administration of adrenergic agents can cause increases in blood glucose, but the effect of inhaled agents is unclear. A double-blind study was performed on 10 patients with type 1 diabetes mellitus (DM) without CF (3 male, 7 female, mean age 25.5 years) and 9 patients with insulin-dependent CF-related diabetes (CFRD) (8 male, 1 female, mean age 21.9 years). On 2 separate days before 9 AM fasting and the morning dose of insulin, 2.5 mg of albuterol or nebulized placebo were given. Blood glucose was measured by finger stick with a glucose reflectance meter before and 15, 30, 45, and 60 min after treatment. No significant changes from baseline or differences between placebo and albuterol occurred in either group. The mean maximum increase from baseline in DM was 20 mg/dl on placebo, and 38 mg/dl on albuterol; in the CFRD, the respective changes were 7 and 7 mg/dl. Two DM patients had a > 50 mg/dl increase on albuterol vs. placebo; no CFRD patients had differences of such magnitude. DM patients had greater increases from baseline than CFRD patients on placebo and albuterol. Differences reached statistical significance at 30 and 45 min on placebo, and 45 min on albuterol. Albuterol 2.5 mg by nebulizer causes no clinically significant increases in blood glucose in DM or CFRD patients. Diabetes patients without CF have a significantly greater increase of glucose with time (placebo or albuterol) than CFRD patients.

Quantification of venlafaxine and O-desmethylvenlafaxine in human serum using HPLC analysis

We describe an isocratic reversed-phase liquid chromatographic method for the determination of venlafaxine (VLX) and its main active metabolite O-desmethylvenlafaxine (ODV) in serum, using haloperidol as internal standard and liquid/liquid extraction for sample preparation. VLX and ODV were separated on a C18 column with a mobile phase of acetonitrile/buffer (30/70, v:v) at 60 degrees C and a flow rate of 1.5 ml/min. The measurement of the native fluorescence signals of the eluted compounds were carried out at 227/300 nm (excitation/emission) without interference from endogenous components in serum. High linearities for VLX and ODV for concentrations between 20 and 500 microg/l were obtained (r = 0.9997). A large spectrum of routinely prescribed drugs did not interfere in the assay. The coefficients of variation for repeatability varied between 5.40% and 5.99% and for reproducibility between 9.43% and 21.63%. Absolute recoveries were more than 52% for both substances.

Therapeutic drug monitoring of trazodone: are there pharmacokinetic interactions involving citalopram and fluoxetine?

OBJECTIVE

Therapeutic drug monitoring (TDM) of the new generation antidepressants is subject of controversial discussion. Nonetheless, TDM may safeguard against drug-drug interactions, can be used to control compliance and is valuable in the investigation of overdose.

METHOD

The aim of this prospective study was to investigate serum levels of trazodone when prescribed as monotherapy or when used in combination with the selective serotonin reuptake inhibitors citalopram and fluoxetine in a simultaneous assay using high-performance liquid chromatography (HPLC). Over a 1-year period, we studied 97 patients (63 females) with depressive syndrome who were subdivided into 3 main diagnostic groups. Fifty-two patients were smokers, the mean age was 39.9 years and the mean weight was 72.4 kg; 40 patients were taking trazodone alone, 41 trazodone in combination with citalopram and 16 patients trazodone in combination with fluoxetine.

RESULTS

The use of citalopram and fluoxetine in combination with trazodone had no significant impact on trazodone serum levels, and the same was true for differences in body weight and smoking behavior. On the other hand, age and sex had a significant influence on the pharmacokinetic pattern of trazodone, causing higher concentrations in females and in older patients. Since the polypharmacy investigated did not change the serum levels of trazodone, we assume that there is no metabolic interaction between trazodone and citalopram and trazodone and fluoxetine. We observed none of the adverse effects which might have been expected, including dizziness, severe headache, daytime sedation, fatigue or the serotonin syndrome even in a mild form.

CONCLUSION

A "double-tracked" antidepressive treatment using trazodone and the SSRIs citalopram and fluoxetine is associated with a wide safety margin.

Etomidate vs. thiopentone in electroconvulsive therapy. An interdisciplinary challenge for anesthesiology and psychiatry

The choice of anesthetic for electroconvulsive therapy is based on the anesthetic requirements to be met and on the agent's impact on the seizure threshold. Thus, the non-barbiturate anesthesia etomidate revealed properties to enhance the seizure duration. Even though precisely this feature makes etomidate so valuable, little research has been done on the use of etomidate in ECT. The aim of the present study was to compare the barbiturate anesthesia thiopentone with etomidate, with the focus of attention being the quality of seizure. In 13 patients, the paradigm of a single intra-individual crossover anesthesia during maintenance ECT was selected. The excitatory effects and the electroencephalographic changes were described. Furthermore, significant differences in motor seizure duration (26.69 sec +/- 9.7 vs. 35.92 sec +/- 9.2; p < 0.007) and EEG seizure duration (39 sec +/- 14.1 sec vs. 61 sec +/- 22.2 sec; p < 0.0009) were observed. Our results confirm previous findings and reveal that after etomidate the quality of seizure can be improved not only in terms of duration. The growing knowledge of the mode of action of anesthetics/hypnotics from an anesthesiological point of view and the better understanding of subcortical and cortical mechanisms, with particular consideration of the motor seizure threshold, facilitate a differentiated choice of the narcotic and the optimization of short anesthesia in the course of electroconvulsive therapy.

Daily psychosocial stressors and cyclic response patterns in urine cortisol and neopterin in a patient with systemic lupus erythematosus

This study investigated the complex biochemical responses to personally meaningful everyday stressors in a patient with systemic lupus erythematosus (SLE). For this purpose, a 52 year-old woman with SLE collected her entire urine for 56 days on a 12-h basis for the determination of cortisol as well as neopterin, a cellular immune parameter. Additionally, using questionnaires, daily notes and interviews, extensive psychosocial and psychological time-series data were collected every 12 h. Cross-correlational analyses of the resulting time-series revealed that stressful incidents were associated with cyclic fluctuations in both urine cortisol and urine neopterin. Specifically, whenever the patient anticipated a moderately stressful incident, urine cortisol initially increased 24 h before the incident and then decreased 12 h before the incident. Moderate stressors not anticipated by the patient were associated with an initial increase 24 h following the incident and then with a decrease after a total of 36 h. Moreover, stressors having to do with the patient's extramarital relationship were followed initially by a decrease in urine neopterin after 36 h and then by an increase after a total of 60 h. Our findings indicate that when investigating the relationship between psychosocial stressors and biochemical activity in SLE, appropriate consideration of the data's dynamic nature may be necessary to avoid flawed conclusions.

Zuclopenthixol-acetate treatment in catatonic patients: the implication of iron metabolism

There is some evidence of ferropenia correlating with neuroleptic malignant syndrome and catatonic symptoms. The aim of this prospective and naturalistic study was to investigate the implications of ferremia in patients undergoing an intramuscular injection treatment of Zuclopenthixol-acetate in Visceolo. We recruited 59 catatonic patients (33 females). Age, sex, psychiatric and somatic diagnoses, body mass index (BMI), dosage and duration of Zuclopenthixol-acetate medication and the timing of the changeover from intramuscular to oral prescription, the single dosage of Clopenthixol if initially coadministered, incidence, onset and duration of transient benign hyperthermia, iron, ferritin, transferrin and saturation values, and white and red blood cell counts as well as liver function and electrolytes were registered. A transient and benign hyperthermic reaction (mean degrees: 37.5 + 0.3 degrees C) lasting for an average of 3.0 + 1.9 d was shown by 72.9% patients (N = 43, 22 females), during a mean treatment period of 5.8 + 3.1 d. These patients were medicated with significant different mean doses of Zuclopenthixol-acetate and compared to the patients with normal body temperature (ANOVA P < 0.01). The duration of Zuclopenthixol-acetate application did not vary between these patients groups. Furthermore, significant differences of iron (59.5 + 30.6 micromol/dl vs. 87.8 + 40.8 micromol/dl; ANOVA P < 0.006) and transferrin saturation values (18.3 + 10.4% vs. 27.2 + 17.0%; ANOVA P < 0.02) were found. Ferritin and transferrin were not implicated in the episode of hyperthermia. Diagnoses, sex, white and red blood cell counts also did not vary between these groups. Our findings indicate a possible involvement of ferropenia in catatonic patients, regardless of the diagnoses, and in the development of benign transient hyperthermia, also known as drug fever.

Simultaneous quantification of citalopram, clozapine, fluoxetine, norfluoxetine, maprotiline, desmethylmaprotiline and trazodone in human serum by HPLC analysis

We describe an analytical procedure for the simultaneous quantification of citalopram (seropram), clozapine (leponex), fluoxetine (fluctine), norfluoxetine, maprotiline (ludiomil), desmethylmaprotiline and trazodone (trittico) in human serum within a period of 11.5 minutes using reversed phase HPLC. After 2 liquid/liquid extractions in the sample preparation phase, the drugs and metabolites were separated on a C18 column using a mobile phase consisting of acetonitrile/buffer (30/70, v:v) at 70 degrees C, a flow rate of 1.5 m/min and haloperidol as internal standard. Absorption and native fluorescence signals of the eluted compounds were detected simultaneously at 260 nm and 227/300 nm (excitation/emission), respectively. The calibration ranges for citalopram, clozapine, fluoxetine, norfluoxetine, maprotiline, and desmethylmaprotiline ranged from 50-400 microg/l and for trazodone from 50-3,200 microg/l. The CVs varied between 0.6% and 5.5% (within-run) and between 3.2% and 7.1% (between-run). Recoveries were > 90% for all pharmaceuticals. We noticed no interferences from several commonly used drugs.

ECT in Austria: Is It Still a Valid Treatment? Appraisal of Present Day Standards in a Psychiatric Hospital

We report on the current experience of electroconvulsive therapy (ECT) in a modern regional psychiatric hospital in Austria. The article describes ECT in 120 psychiatric inpatients during 1980-1987. All patients were hospitalized, the main indications for ECT being "neuroleptic treatment resistance" and "catatonia/stupor." Between 1980-1987, an average of 0.7% of admissions (0.6-2.75%) were treated with a course of 10 (62%) or 15 ECTs (25%), with 4% of patients requiring 15 ECTs or more. In more than one-half of the patients, bilateral electrode placement was used. All ECT was done under anesthesia and muscular relaxation. We find ECT to be a valuable treatment-technique for a subgroup of psychotic inpatients.

The cryosurgical ablation of bone tissue by means of a new miniature cryoprobe -- evaluation of the probe and adaption of the method to in vitro human bone

Until now, modern miniature cryoprobes have been used successfully for the local destruction of soft-tissue tumors without damaging adjacent healthy tissue. In this study, the methodology of cryoablation was applied to bone, and the freezing effect as well as the cooling capacity of the probe were examined. Freezing was performed by cooling one or two probes, with a diameter of 3.2 mm, to -180 degrees C with liquid nitrogen. The cooling capacity of the probes was determined under optic and thermic control in a homogenous reference gel (gelatin), followed by an in vitro measurement on human bone. The simultaneous use of 2 probes resulted in a synergistic effect which produced an almost spherical expansion of frozen area in the homogenous gelatin. In vitro freezing of human tibiae produced equivalent freezing temperatures, with one or two probes, in comparison to the homogenous gelatin. An adequate tissue cooling of bone matrix can be achieved through the use of one or more miniature cryoprobes so that after in vivo testing, the use of this probe could possibly become an alternative or supplement to the surgical resection of pathologic bone processes.

[The influence of daily psychosocial stressors and associated emotions on the dynamic course of urine cortisol and urine neopterin in systemic lupus erythematosus: Experience taken from two "integrative single-case studies"]

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by flare-ups, the cause of which is unknown. According to new stress concepts, two "integrative single-case studies" have been conducted in order to gather evidence about whether daily stressful incidents and associated emotions interfere with the dynamics of urine cortisol and urine neopterin in SLE. Patients under study collected their urine at home, for a period of at least 50 days, on a daily basis, divided into day and night urine. Additionally, patients filled out questionnaires twice a day to determine their emotional state, life style and disease activity. Each week, patients were examined clinically and interviewed to identify the past week's stressors using the Incidents and Hassles Inventory (IHI, Brown and Harris). Statistical analysis of the serial data was performed using time-series analysis according to Box and Jenkins. In both "integrative single-case studies" we were able to demonstrate that stressful incidents predicted an increase in urine neopterin 36 hours (Case 1) to 60 hours (Case 2) later (p < 0.05). Additionally, in Case 1 the neopterin levels were highly associated with stress resulting from the weekly examinations and interviews. Furthermore, in Case 2 it turned out that depending on their predictability stressful incidents were preceded by a decrease in urine cortisol 12 hours earlier or were followed by a decrease in urine cortisol 36 hours later. And finally, emotional irritation was highly correlated with the course of urine-neopterin. In Case 2 irritation led to an increase in urine neopterin 84 hours later. There were no clinical signs of SLE during both prospective studies. In conclusion, our results validate the idea of "integrative single-case studies" as a new "bio-psycho-social" approach in psychoneuroimmunology. Further studies with SLE patients as well as with healthy probands will be necessary in order to both strengthen and generalize these results.

Neurons with two sites of synaptic integration learn invariant representations

Neurons in mammalian cerebral cortex combine specific responses with respect to some stimulus features with invariant responses to other stimulus features. For example, in primary visual cortex, complex cells code for orientation of a contour but ignore its position to a certain degree. In higher areas, such as the inferotemporal cortex, translation-invariant, rotation-invariant, and even view point-invariant responses can be observed. Such properties are of obvious interest to artificial systems performing tasks like pattern recognition. It remains to be resolved how such response properties develop in biological systems. Here we present an unsupervised learning rule that addresses this problem. It is based on a neuron model with two sites of synaptic integration, allowing qualitatively different effects of input to basal and apical dendritic trees, respectively. Without supervision, the system learns to extract invariance properties using temporal or spatial continuity of stimuli. Furthermore, top-down information can be smoothly integrated in the same framework. Thus, this model lends a physiological implementation to approaches of unsupervised learning of invariant-response properties.

Solution structure of a telomeric DNA complex of human TRF1

BACKGROUND

Mammalian telomeres consist of long tandem arrays of double-stranded TTAGGG sequence motif packaged by TRF1 and TRF2. In contrast to the DNA binding domain of c-Myb, which consists of three imperfect tandem repeats, DNA binding domains of both TRF1 and TRF2 contain only a single Myb repeat. In a DNA complex of c-Myb, both the second and third repeats are closely packed in the major groove of DNA and recognize a specific base sequence cooperatively.

RESULTS

The structure of the DNA binding domain of human TRF1 bound to telomeric DNA has been determined by NMR. It consists of three helices, whose architecture is very close to that of three repeats of the c-Myb DNA binding domain. Only the single Myb domain of TRF1 is sufficient for the sequence-specific recognition. The third helix of TRF1 recognizes the TAGGG part in the major groove, and the N-terminal arm interacts with the TT part in the minor groove.

CONCLUSIONS

The DNA binding domain of TRF1 can specifically and fully recognize the AGGGTT sequence. It is likely that, in the dimer of TRF1, two DNA binding domains can bind independently in tandem arrays to two binding sites of telomeric DNA that is composed of the repeated AGGGTT motif. Although TRF2 plays an important role in the t loop formation that protects the ends of telomeres, it is likely that the binding mode of TRF2 to double-stranded telomeric DNA is almost identical to that of TRF1.

Proteinuria and plasma total homocysteine levels in chronic renal disease patients with a normal range serum creatinine: critical impact of true glomerular filtration rate

Conflicting data have been reported concerning the independent association between proteinuria and plasma total homocysteine (tHcy) levels, particularly among chronic renal disease (CRD) patients with a normal range serum creatinine. Studies of this potential relationship have been limited by failure to assess true GFR, failure to assess proteinuria in a quantitative manner, or arbitrary restriction of the range of proteinuria examined. We examined the potential independent relationship between plasma tHcy levels and a wide range of quantitatively determined proteinuria (i.e., 0.000-8.340 g/day), among 109 CRD patients with a normal range serum creatinine (range; 0.8-1.5 mg/dl; median=1.2 mg/dl). Glomerular filtration rate (GFR) was directly assessed by iohexol clearance, and plasma status of folate, pyridoxal 5'-phosphate, and B12, along with serum albumin, were also determined. Linear modeling with ANCOVA revealed that proteinuria was not independently associated with tHcy levels (partial R=0.127; P=0.201), after adjustment for potential confounding by GFR (partial R=0.408; P<0.001), age, sex, plasma B-vitamin status, and serum albumin. Moreover, descending across quartiles (Q) [from Q4 to Q1] of GFR, ANCOVA-adjusted (i.e., for age, sex, and folate status) geometric mean tHcy levels (micromol/l) were significantly increased: tHcy Q4 GFR=9.6; tHcy Q3 GFR=10.5; tHcy Q2 GFR=11.9; tHcy Q4 GFR=14.5; P<0.001 for overall Q difference. We conclude that across a broad spectrum of quantitatively determined proteinuria, after adjustment for true GFR, in particular, there is no independent relationship between proteinuria and tHcy levels among CRD patients with a normal range serum creatinine.

Supervised and unsupervised learning with two sites of synaptic integration

Many learning rules for neural networks derive from abstract objective functions. The weights in those networks are typically optimized utilizing gradient ascent on the objective function. In those networks each neuron needs to store two variables. One variable, called activity, contains the bottom-up sensory-fugal information involved in the core signal processing. The other variable typically describes the derivative of the objective function with respect to the cell's activity and is exclusively used for learning. This variable allows the objective function's derivative to be calculated with respect to each weight and thus the weight update. Although this approach is widely used, the mapping of such two variables onto physiology is unclear, and these learning algorithms are often considered biologically unrealistic. However, recent research on the properties of cortical pyramidal neurons shows that these cells have at least two sites of synaptic integration, the basal and the apical dendrite, and are thus appropriately described by at least two variables. Here we discuss whether these results could constitute a physiological basis for the described abstract learning rules. As examples we demonstrate an implementation of the backpropagation of error algorithm and a specific self-supervised learning algorithm using these principles. Thus, compared to standard, one-integration-site neurons, it is possible to incorporate interesting properties in neural networks that are inspired by physiology with a modest increase of complexity.

Efficient evaluation of serial sections by iterative Gabor matching

Evaluation of electron microscopic images of serial sections is a time-consuming process requiring a high level of expertise. Here we present an algorithm to ease and accelerate this process. It is a modification of an algorithm successfully used in computer vision for object recognition. However, rather than recognising individual structures, we estimate the spatial mapping of a whole section onto the consecutive one. This mapping is used to transfer labelled information of the very first section, e.g. a classification by a human expert of different visible structures, onto structures visible in the next section. We investigate its performance on an artificially constructed benchmark as well as on real electron microscopic samples taken in primary visual cortex and demonstrate its potential for dramatically facilitating the evaluation process of serial sections.

Ethanol reduces excitability in a subgroup of primary sensory neurons by activation of BK(Ca) channels

Ethanol effects on the central nervous system have been well investigated and described in recent years; modulations, by ethanol, of several ligand-gated and voltage-gated ion channels have been found. In this paper, we describe a shortening of action potential duration (APD) by ethanol in approximately equal to 40% of small diameter neurons in rat dorsal root ganglia (DRG). In these neurons, designated as group A neurons, we observed an ethanol-induced increase in whole-cell outward-current. As iberiotoxin, a specific blocker of large-conductance calcium-activated K+ channels (BK(Ca) channels), blocks the effects of ethanol, we investigated the interaction between these channels and ethanol in outside-out patches. Open probability of BK(Ca) channels was increased 2-6 x depending on the concentration (40-80 mM approximately equal to 2-4 per thousand v/v) of ethanol. Functional consequences were a prolongation of the refractory period, which was reversible after addition of iberiotoxin, and reduced firing frequency during ethanol application. In contrast, another type of neuron (group B) showed a prolonged APD during application of ethanol which was irreversible in most cases. In 90% of cases, neurons of group A showed a positive staining for isolectin B4 (I-B4), a marker for nociceptive neurons. We suggest that the activation of BK(Ca) channels induced by clinically relevant concentrations of ethanol, the resulting modulations of APD and refractory period of DRG neurons, might contribute to clinically well-known ethanol-induced analgesia and paresthesia.

Non-contact eye-tracking on cats

The objective of visual systems neuroscience has shifted over the past few years from determining the receptive fields of cells towards the understanding of higher level cognition in awake animals viewing natural stimuli. In experiments with awake animals it is important to control the relevant aspects of behavior. Most important for vision science is the control of the direction of gaze. Here we present Dual Purkinje eye-tracking on cats, which--as a non-contact method--brings a number of advantages. Along with the presented methods for calibration and for synchronization to off-the-shelf video presentation hardware, this method allows high precision experiments to be performed on cats freely viewing videos of natural scenes.

[Living kidney donation--selection criteria, preparation and follow-up]

Since a dialysis patient in Austria still waits on average more than two years for a renal transplant, the question of a transplant from a living donor is very interesting. We differentiate between related and non-related living donors, who are chosen on the basis of medical criteria and emotional ties. Austria's first three kidney transplants from related donors were performed in 1967. Since then a total of 317 kidneys from genetically related donors have been transplanted until December 31, 2000. Transplants from non-related living donors were performed once in 1982, once in 1990 and since 1995 in a steadily increasing number each year, until they reached 47 by December 31, 2000. The United Network for Organ Sharing calculated the ten-year survival rate for functional grafts for a four-year period (1995-1998) in more than 30,000 renal transplant recipients from HLA-identical twins, non-related living donors, parent and cadaver donors. As anticipated, this study demonstrates that HLA-identical twins (n = 1,581) have the most functional grafts (81%), followed by non-related donor-recipients (n = 1,704) at 67% despite their often poor HLA match, parent-child transplants (n = 2,428) at 62% and cadaver renal grafts (n = 26,178) at 50%. Therefore, medical aspects as well as influences from the psychosocial environment would appear to be decisive for transplantation success. Thus, when choosing from several possible living donors it is absolutely justifiable to choose a donor with a poorer HLA match but good emotional ties. Such a choice requires strict selection criteria, and surgical preparation and follow-up demand the greatest care. While the criteria given in this paper are meant to be guidelines to help in deciding for a liver donor, they certainly do not rule out a different approach following critical reflection and participation by the affected parties, namely donor and recipient, as well as their advisors, nephrologist, transplant surgeon and psychotherapist. At the same time we need to make every effort to further intensify the use of cadaver kidneys. Only in this way can we ensure optimal implementation of all the resources available to us for supplying renal grafts to dialysis patients.

Low frequency rTMS as an add-on antidepressive strategy: heterogeneous impact on 99mTc-HMPAO and 18 F-FDG uptake as measured simultaneously with the double isotope SPECT technique. Pilot study

Single photon emission computed tomography (SPECT) and positron emission tomography (PET) are examination procedures that have shown that repetitive transcranial magnetic stimulation (rTMS) is biologically active. The aim of the present study was to investigate the patterns of regional cerebral 18F-fluorodeoxyglucose (18F-FDG) uptake and regional 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) uptake simultaneously during a series of therapeutic rTMS at low frequency. Four drug-resistant depressed patients underwent 10 rTMS as an add-on measure over 14 days. One day before and one day after TMS, simultaneous measurements of 18F-FDG, representing regional cerebral metabolic rate (rCMR), and 99mTc-HMPAO, representing regional cerebral blood flow (rCBF), were carried out. A conventional double head SPECT camera with 511 keV collimators was used. Statistically significant simultaneous overall changes of rCBF and rCMR were found in the upper prefrontal regions bilaterally in terms of increased uptake rates and in the left gyrus frontalis inferior in terms of decreased uptake rates of both isotopes compared to controls. Although this method improves our understanding of rTMS mechanism, there are limitations due to the lower resolution provided. Therapeutic rTMS seems to influence distinct, cortical regions affecting rCBF and rCMR.

Zotepine in the treatment of acute hospitalized schizophrenic episodes

The atypical antipsychotic zotepine was studied in an open, multicentre uncontrolled, post-marketing surveillance study in 108 schizophrenic patients hospitalized in 12 trial centres in Austria. Within the dosage range of 50-450 mg (mean at the end of the study, 207 +/- 125 mg/day), a significant reduction of positive as well as negative symptoms was noted. There was no increase in extrapyramidal side-effects during the study and a significant decrease in akathisia scores. The medication was well tolerated during the 42-day observation period. Zotepine improved both positive and negative symptoms and was not accompanied by extrapyramidal side-effects, justifying its classification as an atypical antipsychotic.

Chronic renal transplantation: a model for the hyperhomocysteinemia of renal insufficiency

Renal transplant recipients (RTR) are considered representative of patients with chronic renal insufficiency (CRI) in general with respect to both reduced, progressively declining renal function, and increased risk for cardiovascular disease (CVD). In accord with this argument, we hypothesized that total (t) plasma concentrations of the putatively atherothrombotic amino acid homocysteine (Hcy) would be equivalent in RTR and CRI patients with comparable renal function. We determined plasma tHcy, folate, pyridoxal 5'-phosphate, and B12 concentrations, in addition to serum creatinine and albumin concentrations, in 86 chronic, stable RTR, and 238 patients with CRI. Within comparable ranges of serum creatinine (i.e. RTR=0.6-4.2 mg/dl; CRI=0.7-4.1 mg/dl), tHcy concentrations did not differ between the two groups (RTR=15.0 micromol/l; CRI=14.9 micromol/l, P=0.899). ANCOVA revealed that renal function, gauged as a simple creatinine measurement, was the major independent determinant of plasma tHcy concentrations, accounting for approximately 80-90% of the total variability in tHcy predicted by the full model (i.e. full model R(2)) containing, in addition to creatinine, the seven other potential explanatory variables. If controlled trials confirm that tHcy-lowering treatment reduces CVD events rates in RTR, these results should be applicable to CRI patients in general.

Hemolytic-uremic syndrome surveillance to monitor trends in infection with Escherichia coli O157 and non-O157 enterohemorrhagic E. coli in Austria

Austrian data underline that relying on the number of enterohemorrhagic Escherichia coli (EHEC) O157 strains isolated from clinical specimens does not allow assessment of the actual incidence of EHEC infections. A hospital-based system for identification of hemolytic-uremic syndrome cases based on voluntary cooperation was established in 1995 and provides information needed to monitor trends in the incidence of O157 and non-O157 EHEC infections.

Mechanisms to synchronize neuronal activity

Temporal aspects of neuronal activity have received increasing attention in recent years. Oscillatory dynamics and the synchronization of neuronal activity are hypothesized to be of functional relevance to information processing in the brain. Here we review theoretical studies of single neurons at different levels of abstraction, with an emphasis on the implications for properties of networks composed of such units. We then discuss the influence of different types of couplings and choices of parameters to the existence of a stable state of synchronous or oscillatory activity. Finally we relate these theoretical studies to the available experimental data, and suggest future lines of research.

Energy dependence of quasiparticle relaxation in a disordered fermi liquid

A spectroscopic method is applied to measure the inelastic quasiparticle relaxation rate in a disordered Fermi liquid. The quasiparticle relaxation rate gamma is deduced from the magnitude of fluctuations in the local density of states, which are probed using resonant tunneling through a localized impurity state. We study its dependence on the excitation energy E measured from the Fermi level. In a disordered metal (heavily doped GaAs) we find that gamma~E3/2 within the experimentally accessible energy interval, in agreement with the Altshuler-Aronov theory for electron-electron interactions in diffusive conductors.

Maintenance electroconvulsive therapy in affective and schizoaffective disorder

Twenty-one patients (13 depressives and 8 schizoaffectives) who underwent maintenance electroconvulsive therapy (M-ECT) were compared with controls who received maintenance pharmacotherapy alone. Measures of effectiveness and safety of maintenance treatment were prospectively obtained during a 1-year follow-up. Survival analysis demonstrated a significantly better outcome defined by time to rehospitalization for all patients of the M-ECT group. Regarding the subgroups, depressives of the M-ECT group had markedly decreased rehospitalization rates compared to depressive controls. Furthermore, M-ECT in depressives resulted in a significant reduction in hospitalization rates and duration during follow-up. In schizoaffective patients, a significant difference in survival time was found in favor of the M-ECT group. In both groups, schizoaffectives had a markedly poorer outcome compared to depressive subjects. Our results indicate that in selected patients M-ECT, at least in combination with supporting medication, may be an efficient and safe alternative to pharmacological continuation or maintenance therapy alone.

NOSIP, a novel modulator of endothelial nitric oxide synthase activity

Production of nitric oxide (NO) in endothelial cells is regulated by direct interactions of endothelial nitric oxide synthase (eNOS) with effector proteins such as Ca2+-calmodulin, by posttranslational modifications such as phosphorylation via protein kinase B, and by translocation of the enzyme from the plasma membrane caveolae to intracellular compartments. Reversible acylation of eNOS is thought to contribute to the intracellular trafficking of the enzyme; however, protein factor(s) that govern the translocation of the enzyme are still unknown. Here we have used the yeast two-hybrid system and identified a novel 34 kDa protein, termed NOSIP (eNOS interacting protein), which avidly binds to the carboxyl-terminal region of the eNOS oxygenase domain. Coimmunoprecipitation studies demonstrated the specific interaction of eNOS and NOSIP in vitro and in vivo, and complex formation was inhibited by a synthetic peptide of the caveolin-1 scaffolding domain. NO production was significantly reduced in eNOS-expressing CHO cells (CHO-eNOS) that transiently overexpressed NOSIP. Stimulation with the calcium ionophore A23187 induced the reversible translocation of eNOS from the detergent-insoluble to the detergent-soluble fractions of CHO-eNOS, and this translocation was completely prevented by transient coexpression of NOSIP in CHO-eNOS. Immunofluorescence studies revealed a prominent plasma membrane staining for eNOS in CHO-eNOS that was abolished in the presence of NOSIP. Subcellular fractionation studies identified eNOS in the caveolin-rich membrane fractions of CHO-eNOS, and coexpression of NOSIP caused a shift of eNOS to intracellular compartments. We conclude that NOSIP is a novel type of modulator that promotes translocation of eNOS from the plasma membrane to intracellular sites, thereby uncoupling eNOS from plasma membrane caveolae and inhibiting NO synthesis.

Top-down processing mediated by interareal synchronization

Perception and cortical responses are not only driven "bottom-up" by the external stimulus but are altered by internal constraints such as expectancy or the current behavioral goal. To investigate neurophysiological mechanisms of such top-down effects, we analyzed the temporal interactions of neurons on different levels of the cortical hierarchy during perception of stimuli with varying behavioral significance. We found that interareal interactions in a middle-frequency range (theta and alpha; 4-12 Hz) strongly depend on the associated behavior, with a phase relationship and a layer specificity indicating a top-down-directed interaction. For novel unexpected stimuli, presumably processed in a feed-forward fashion, no such interactions occurred but high-frequency interactions (gamma; 20-100 Hz) were observed. Thus corticocortical synchronization reflects the internal state of the animal and may mediate top-down processes.

A case of pharmacokinetic interference in comedication of clozapine and valproic acid

In 4-6% of treatment histories, clozapine induces generalized seizures by reducing the seizure threshold. Despite the knowledge of high risks combined therapy (such as bone marrow suppression, pathological EEG changes), some authors even suggest the prophylactic combination with anticonvulsants in high dose treatment of clozapine. We report a case of a 33-year-old female patient, a heavy smoker, suffering from mixed schizoaffective disorder from 1989 onwards. At her 8th admission in 1998, she was rehospitalized after experiencing her first generalized seizure under clozapine treatment, although no seizure phenomenon or other relevant side-effects under several previous clozapine therapies had been observed. Therefore, she received a valproic acid co-medication during her clozapine therapy. Based on therapeutic drug monitoring of clozapine (weekly) under compliance-controlled conditions, the serum levels of clozapine significantly decreased, probably induced by valproic acid. According to the literature, this case report might support the clinical relevance of therapeutic drug monitoring when clozapine therapy is combined with valproic acid as co-medication.

Apoptosis of tubular epithelial cells in familial juvenile gouty nephropathy

Two patients, a 47-year-old woman suffering from chronic renal failure, hyperuricemia and gout, and her 26-year-old son with hyperuricemia and chronic renal failure, are described. The father and two siblings of the woman had died of chronic renal failure. Both patients had a markedly reduced fractional excretion of urate, which was significantly increased by both benzbromarone and probenecid. A renal biopsy of the son revealed an unspecific chronic tubulointerstitial nephropathy. By light microscopy, many proximal tubular epithelial cells showed signs of apoptosis, which was confirmed with the specific TUNEL assay. We propose a hypothesis based on a gain-of-function mutation of the luminal anion exchanger of the proximal tubulus to explain reduced uric acid excretion, dominant inheritance and apoptosis of tubular epithelial cells in this rare disease. Treatment with a combination of allopurinol to reduce the renal urate load and benzbromarone to block the tubular anion exchanger and normalize fractional uric acid excretion is suggested.

Pyuria in patients treated with indinavir is associated with renal dysfunction

BACKGROUND

Indinavir therapy is associated with a continuum of crystal-related syndromes, including nephrolithiasis, renal colic, flank pain without recognizable stone formation, dysuria and asymptomatic crystalluria. A frank nephropathy has been recognized recently as part of the spectrum.

METHODS

A retrospective analysis of 72 HIV-infected individuals receiving indinavir was performed to identify the frequency and risk factors for indinavir-associated nephropathy and urinary complications. Individuals treated with nucleoside analogues alone served as controls.

RESULTS

Mean serum creatinine levels rose from 1.03 +/- 0.16 mg/dl to 1.11 +/- 0.22 mg/dl at week 12 and 1.15 +/- 0.27 mg/dl at week 24 (both, p < 0.01). Thirteen individuals developed serum creatinine levels > or =1.4 mg/dl. Increased serum creatinine levels were found more frequently in women (p < 0.01) and were associated with pyuria and microhematuria (p < 0.01). Frank renal colic and/or nephrolithiasis (seven patients) and urinary pH were not associated with serum creatinine levels > or =1.4 mg/dl. The mean duration of indinavir treatment, until sterile pyuria occurred, were 22 weeks and 32 weeks until the first rise of serum creatinine levels to > or =1.4 mg/dl. Ten patients showed both findings, pyuria preceded the first rise in serum creatinine levels to > or = 1.4 mg/dl (18 vs. 27 weeks, p = 0.02). Renal biopsy, done in three patients, revealed tubulointerstitial disease with crystals in collecting ducts. In 21 patients, among them 11 with pyuria, indinavir was replaced for various reasons and pyuria disappeared in nine. In these patients mean serum creatinine levels decreased from 1.43 mg/dl at withdrawal of indinavir to 1.04 mg/dl three months later (p < 0.01).

CONCLUSION

Indinavir therapy is associated with a decrease in renal function which is reversible after withdrawal. In addition, indinavir-associated tubulointerstitial disease does no in patients taking indinavir may help to identify patients being at risk for nephrotoxicity.

A spike based learning rule for generation of invariant representations

For biological realism, models of learning in neuronal networks often assume that synaptic plasticity solely depends on locally available signals, in particular only on the activity of the pre- and post-synaptic cells. As a consequence, synapses influence the plasticity of other synapses exclusively via the post-synaptic activity. Inspired by recent research on the properties of apical dendrites it has been suggested, that a second integration site in the apical dendrite may mediate specific global information. Here we explore this issue considering the example of learning invariant responses by examining a network of spiking neurones with two sites of synaptic integration. We demonstrate that results obtained in networks of units with continuous outputs transfer to the more realistic neuronal model. This allows a number of more specific experimental predictions, and is a necessary step to unified description of learning rules exploiting timing of action potentials.

Bi-directional interactions between visual areas in the awake behaving cat

The study of the cooperativity among cortical areas is essential to our understanding of brain functioning. Here we investigated the relative contributions of top-down and bottom-up directed interactions between area 17 and area 7 of the cat visual system. Bipolar local field potentials were recorded while the animals performed a go/no-go task or were in a quiet resting state. The data were analyzed by applying measures of interaction based on the Wiener-Granger causality concept. We found that during the visual task top-down directed interactions were of a similar magnitude as the bottom-up component. Second, interareal couplings tended to increase in conditions requiring a discriminative effort. Third, during behaviors not dominated by visual processing non-directed interactions increased.

Integrating top-down and bottom-up sensory processing by somato-dendritic interactions

The classical view of cortical information processing is that of a bottom-up process in a feedforward hierarchy. However, psychophysical, anatomical, and physiological evidence suggests that top-down effects play a crucial role in the processing of input stimuli. Not much is known about the neural mechanisms underlying these effects. Here we investigate a physiologically inspired model of two reciprocally connected cortical areas. Each area receives bottom-up as well as top-down information. This information is integrated by a mechanism that exploits recent findings on somato-dendritic interactions. (1) This results in a burst signal that is robust in the context of noise in bottom-up signals. (2) Investigating the influence of additional top-down information, priming-like effects on the processing of bottom-up input can be demonstrated. (3) In accordance with recent physiological findings, interareal coupling in low-frequency ranges is characteristically enhanced by top-down mechanisms. The proposed scheme combines a qualitative influence of top-down directed signals on the temporal dynamics of neuronal activity with a limited effect on the mean firing rate of the targeted neurons. As it gives an account of the system properties on the cellular level, it is possible to derive several experimentally testable predictions.

Local and global gating of synaptic plasticity

Mechanisms influencing learning in neural networks are usually investigated on either a local or a global scale. The former relates to synaptic processes, the latter to unspecific modulatory systems. Here we study the interaction of a local learning rule that evaluates coincidences of pre- and postsynaptic action potentials and a global modulatory mechanism, such as the action of the basal forebrain onto cortical neurons. The simulations demonstrate that the interaction of these mechanisms leads to a learning rule supporting fast learning rates, stability, and flexibility. Furthermore, the simulations generate two experimentally testable predictions on the dependence of backpropagating action potential on basal forebrain activity and the relative timing of the activity of inhibitory and excitatory neurons in the neocortex.

Transcranial magnetic stimulation induces 'pseudoabsence seizure'

OBJECTIVE

Several studies support the hypothesis of an antidepressive or mood-enhancing effect of repetitive transcranial magnetic stimulation (rTMS) on depressive patients. The most acute concern regarding rTMS is possible seizure induction; therefore, reports on seizure during rTMS are of special significance.

METHOD

We describe a case in which high frequency rTMS over the left dorsolatero-prefrontal cortex (DLPC) applied as an add-on antidepressive strategy may have induced a frontal lobe complex partial seizure in a female patient affected by drug-resistant depression.

RESULTS

The epileptic seizure was self-limited, and the patient did not report any physical sequelae. The psychopathological improvement, observed immediately after the incident in question, did not last.

CONCLUSION

In this case train duration in rTMS, combined with drugs modulating the norepinephrine turnover, may have contributed to the occurrence of this complex partial seizure, which neuroanatomically seems to be localized in the DLPC.

Preliminary findings of simultaneous 18F-FDG and 99mTc-HMPAO SPECT in patients with depressive disorders at rest: differential correlates with ratings of anxiety

The assumption of a dynamic coupling between regional cerebral blood flow (rCBF) and cerebral glucose metabolic rates (rCMRGlu) has been challenged by simultaneous measurements of both. Through the use of a dual-headed gamma camera with a 511-keV collimator applying the double isotope 18F-FDG and 99mTc-HMPAO SPECT technique, the uptake rates of these isotopes can be semi-quantitatively evaluated. Sixteen depressed patients, diagnosed by ICD-10 criteria and assessed with the 17-item Hamilton Rating Scale for Depression (HRSD), were studied. Based on the severity of HRSD-rated anxiety (item 10: low=1-21; high=3-4), two eight-patient subgroups were formed and compared with 12 age- and handedness-matched healthy control subjects. As regions of interest, we selected areas implicated in the neuroanatomy of anxiety and depression: hippocampus (hippo), basal ganglia (BG) and gyri temporales superiores (G.t.s.). In the control subjects, a significant statistical coupling between rCBF and rCMRGlu was revealed by the Spearman correlation coefficient only in left hippo and left BG. Patients in the low-anxiety subgroup demonstrated a marked dynamic coupling bilaterally for the G.t.s., while patients in the high-anxiety subgroup showed a significant statistical correlation of rCBF and rCMRGlu only in the left G.t.s. These findings indicate that a dynamic coupling between blood flow and glucose metabolism exists only in distinct brain regions, and that the depressive illness has an uncoupling effect on this correlation in the left BG. Furthermore, our results suggest that the HRSD anxiety score might interact with the underlying depressive illness to influence the relationship of rCBF and rCMRGlu.

The effects of cromolyn sodium and nedocromil sodium in early asthma prevention

The possibility of irreversible obstruction and therefore the need for early intervention is being much debated. Some investigators suggested that delay in starting inhaled corticosteroids will result in irreversible obstruction. Our own long-term study, specifically designed to detect irreversible obstruction showed that a step-wise approach (starting with cromolyn sodium and switching to inhaled corticosteroids if clinical control and pulmonary function tests are not satisfactorily controlled) resulted in an increase in pulmonary function and not a deterioration. There was no evidence that a delay in starting inhaled corticosteroids will result in irreversible obstruction or clinical worsening. However, delay in starting cromolyn sodium in patients treated with bronchodilators alone did result in worsening pulmonary function tests and worse clinical outcomes. One study from Finland and another study from Australia came to the same conclusion. Even though some studies with cromolyn sodium did not show benefit in the first year of life, other studies did show a good response. The choice between nonsteroidal drugs, such as cromolyn sodium and inhaled corticosteroids as first-line drugs, has to be made on the risk/benefit ratio of these drugs. Although in severe asthma inhaled corticosteroids have greater efficacy, in mild-to-moderate asthma there is comparable efficacy, and the nonsteroidal drugs have better safety. A step-wise approach is still a logical approach