Ventromedial prefrontal cortex activation and neurofeedback modulation during episodic future thinking for individuals with suicidal thoughts and behaviors

Individuals experiencing suicidal thoughts and behaviors (STBs) show less specificity and positivity during episodic future thinking (EFT). Here, we present findings from two studies aiming to (1) further our understanding of how STBs may relate to neural responsivity during EFT and (2) examine the feasibility of modulating EFT-related activation using real-time fMRI neurofeedback (rtfMRI-nf). Study 1 involved 30 individuals with major depressive disorder (MDD; half with STBs) who performed an EFT task during fMRI, for which they imagined personally-relevant future positive, negative, or neutral events. Positive EFT elicited greater ventromedial prefrontal cortex (vmPFC) activation compared to negative EFT. Importantly, the MDD + STB group exhibited reduced vmPFC activation across all EFT conditions compared to MDD-STB; although EFT fluency and subjective experience remained consistent across groups. Study 2 included rtfMRI-nf focused on vmPFC modulation during positive EFT for six participants with MDD + STBs. Results support the feasibility and acceptability of the rtfMRI-nf protocol and quantitative and qualitative observations are provided to help inform future, larger studies aiming to examine similar neurofeedback protocols. Results implicate vmPFC blunting as a promising treatment target for MDD + STBs and suggest rtfMRI-nf as one potential technique to explore for enhancing vmPFC engagement.

Determination of Magnesium and Calcium in Foods by Atomic Absorption Spectrometry after Microwave Digestion: NMKL Collaborative Study

On the basis of results of the performed collaborative study, the 49th Annual General Meeting of the Nordic Committee on Food Analysis (NMKL) in The Faroe Islands, August 1995, approved this method to be printed and included in NMKL's collection of methods of analysis of foods. Eleven laboratories participated in an interlaboratory methods-performance (collaborative) study of a method for determining magnesium and calcium in foodstuffs by atomic absorption spectrometry (AAS) after wet microwave digestion. The study was preceded by a practice round of familiarization samples. The method was tested on 7 materials: 5 foods (apple, milk powder, minced fish, wheat bran, and chocolate cake) and 2 composite diets ranging in Mg content from 240 to 3900 mg/kg and in Ca content from 290 to 9300 mg/kg. The materials were presented to study participants as blind duplicates, and participants were asked to perform single determinations on each sample. Repeatability relative standard deviations (RSDr) ranged from 1.9 to 4.9% for Mg and from 2.2 to 8.1 % for Ca. Reproducibility relative standard deviations (RSDR) ranged from 4.0 to 13% for Mg and from 5.9 to 23% for Ca. For Ca, lowest RSDR values were found for samples with high concentrations of Ca (>3800 mg/kg sample) and with nitrate ion residues of <1.3% (w/v).

Prevalence and heritability of symptomatic syringomyelia in Cavalier King Charles Spaniels and long-term outcome in symptomatic and asymptomatic littermates

Background

Syringomyelia (SM) is common in the Cavalier King Charles Spaniel (CKCS). Dogs with syringes express clinical signs or might be clinically silent.

Objectives

To investigate the prevalence and heritability of symptomatic SM, the association between clinical signs and magnetic resonance imaging (MRI) findings, and long‐term outcome.

Animals

All CKCS registered in the Danish Kennel Club in 2001 (n = 240).

Methods

A cross‐sectional questionnaire‐based prevalence study validated by telephone interviews and clinically investigated clinical signs of SM. Dogs were 6 years at the time of investigation. A prospective observational litter study including clinical investigations, MRI and 5‐year follow‐up of symptomatic and asymptomatic siblings. Heritability was estimated based on the scale of liability in the study population and litter cohort.

Results

The cross‐sectional study estimated a prevalence of symptomatic SM at 15.4% in the population. Thirteen symptomatic and 9 asymptomatic siblings participated in the litter study. Spinal cord syringes were confirmed in 21 of 22 littermates (95%). Syrinx diameter and mean syrinx : spinal cord ratio were significantly correlated with clinical signs (P < .01). Estimated heritability of symptomatic SM was 0.81. Symptomatic SM motivated euthanasia in 20%. Dogs with syringes, which expressed no clinical signs at the age of 6, remained asymptomatic in 14/15 cases (93%).

Conclusions and Clinical Importance

The prevalence of symptomatic SM is high and genetics have a high impact on clinical disease expression. Further investigations of factors influencing the outbreak threshold of clinical signs of SM are desirable.

Biologische Wirkungen photochemischer Wasserstoffperoxydbildung

Die photochemische H2O2-Bildung wird als eine weitere Möglichkeit geprüft, um cytotoxische Effekte in der Mikrobiologie hervorzurufen. Suspensionen von Proteus vulgaris (SG 2), die Anthrachinonsulfonsäuren in einer Konzentration von 6·10-4-m. enthalten, werden mit Licht der Wellenlängen &gt; 360 mμ bestrahlt und einerseits die resultierende H2O2-Konzentration gemessen, andererseits die Keimzahlen zu verschiedenen Zeiten bestimmt. Unter vorliegenden Bedingungen wird eine so starke Wirkung erzielt, daß bei Versuchsende ein Bruchteil der eingesetzten Bakterien vermehrungsfähig bleibt. Aus dem Vergleich mit zugesetztem H2O2 wird gefolgert, daß sich die oxydationsfreudigen Radikale OH und HO2 maßgeblich an der cytotoxischen Wirkung beteiligen.

Electroporation of cell membranes supporting penetration of photodynamic active macromolecular chromophore dextrans

The aim is to demonstrate that macromolecular chromophore dextrans (Cibacron-dextran) acting as photosensitizers can be transported easily into cancer cells by electroporation of their membranes (short electric pulses on cell suspension between electrodes). There are two possibilities, either:(A)irradiation starts with the electropulse-showed with easily penetrating thiopyronin-yielding nearly 100% dead cells;(B)irradiation starts after a resealing time of membrane pores during which macromolecular photosensitizers can penetrate into cells. In this way, fractions of Cibacron-dextran with molecular weights (Mw) 3300, 10,900 and 500,000 are now able to kill. This combination of bioelectrochemistry and photobiology will be suitable also for other biopolymers, connected with photodynamic active chromophores (e.g. chromopeptides) to transport them through cell walls and membranes into cells and tissues. The human cancer cells U-935 and K-562 (pulsed by 1.15 kV/cm field strength) additionally or synergistically reach high rates of necrotic cells (colored by trypan blue) by this combination.

Inhibition of proliferation of human lymphoma cells U937 by a 50 Hz electromagnetic field

Weak pulsating electromagnetically induced fields (PEMF) by Helmholtz coils changes cell metabolism, if cells are treated with a certain range of frequency and amplitude. The influence on proliferation of human histiocytic lymphoma cells U937 has been studied applying a sinusoidal 50 Hz field with amplitudes of the flux density B = 0.3 to 4.7 mT for 4 days. No difference between experiment and control was found in the region 0.3 and 2 mT. However, stronger fields (> or =2.5 mT) inhibit cell division. Fields > or =3.5 mT treatment kill > or =80% of the cell number at the beginning (1.5 x 10(5)/ml). This effect may be an electromagnetocally induced cell death as the first step for a non-invasive application on cell proliferation process.

Acceleromyography of the orbicularis oculi muscle II: comparing the orbicularis oculi and adductor pollicis muscles

BACKGROUND

The orbicularis oculi (OO) muscle has been recommended for neuromuscular monitoring when the adductor pollicis (AP) muscle is not available. We investigated whether neuromuscular block could be measured reliably from the orbital part of the OO muscle by the use of acceleromyography.

METHODS

During propofol, fentanyl, and alfentanil anaesthesia two TOF-Guards (Organon Teknika NV, Boxtel, the Netherlands) with acceleration transducers placed on the distal phalanx of the thumb and over the middle of the eyebrow, respectively, were used to measure neuromuscular block simultaneously in 23 patients during vecuronium-induced and neostigmine-antagonized neuromuscular block. For both muscles, the simultaneously recorded first response (T1) in the train-of-four (TOF) and TOF-ratio were measured both during onset and recovery of the block. Furthermore, both the AP muscle T1 and TOF-ratio responses were plotted against 10% intervals of the OO muscle responses during onset and recovery, respectively.

RESULTS

The orbicularis oculi muscle had a shorter latency and a faster recovery to TOF-ratio 0.80 compared with the AP muscle. During onset and recovery, pronounced variations of the AP muscle T1 and TOF-ratio responses were observed when compared with the OO muscle.

CONCLUSION

A significant clinical disagreement exists between the degree of paralysis measured at the OO and the AP muscles. It is impossible to obtain a reasonable estimate of the degree of block at the AP muscle when the block is measured from the OO muscle with acceleromyography. If used, there is substantial risk of overlooking a residual block, and adequate recovery of the block should be confirmed by a final AP muscle measurement.

Acceleromyography of the orbicularis oculi muscle I: significance of the electrode position

BACKGROUND

This study aimed to establish the best position of the stimulating electrodes for facial nerve stimulation during acceleromyographic monitoring from the orbital part of the orbicularis oculi muscle.

METHODS

In 59 anaesthetised patients, an acceleration transducer was positioned over the middle of the eyebrow. In 47 patients, supramaximal train-of-four (TOF) stimulation was established for four electrode pairs with different positions along the facial nerve and behind the ear. The electrode pair with the lowest, the intermediate, and the highest supramaximal stimulating current based on first response (T1) in TOF was found in each patient. A possible response from direct muscle stimulation was evaluated during complete vecuronium block. In 12 patients, supramaximal stimulation was established using a stimulation sequence different from the one used in the first part of the study.

RESULTS

The best positions for the stimulating electrodes were either with both electrodes just lateral to the eye, or with one electrode lateral to the eye and one in front of the ear. In most patients, supramaximal stimulation was obtained at these positions at 20-60 mA. However, in 10-21% of the patients, supramaximal stimulation could not be obtained. During complete block, 1-4 responses with a twitch height of 3-11% were recorded in 80% of the patients.

CONCLUSION

The best placements of the stimulation electrodes are either just lateral to the eye or along the zygomatic arch. However, supramaximal stimulation may often not be obtainable, and activation of other facial muscles may be a confounding factor that may impede correct evaluation of the degree of neuromuscular block.

Development of methods for the determination of vitamins A, E and beta-carotene in processed foods based on supercritical fluid extraction: a collaborative study

New methodologies based on supercritical fluid extraction (SFE) have been developed for the determination of fat-soluble vitamins in processed foods. The results obtained so far indicate that SFE is well suited to extraction of fat-soluble vitamins from food products, although validation work is required to establish accuracy and precision. The vitamins investigated were A, E and beta-carotene, and the processed foods were UHT milk, milk powder, minced meat, liver paste, infant formula, canned baby food and margarine. Extraction equipment employed analyte collection on either a solid-phase trap or in a solvent. After extraction, the samples were saponified and the vitamins determined using reversed-phase liquid chromatography with ultraviolet or fluorescence detection. Sample throughput was at least 12 samples day(-1), i.e. at least twice the number achievable with a conventional extraction methodology. The detection limits for the vitamins in different processed foods were well below 0.1 microg g(-1). Recoveries (in comparison with vitamin levels obtained using conventional solvent extraction) were close to 100% for experienced personal with access to modern automatic equipment. To reach this level, it was necessary to protect the vitamins with an antioxidant during the different steps of the analysis procedure, to add methanol or ethanol to the extraction cell to facilitate the analyte extraction from the food matrix, and when using a solid-phase trap, to employ a fractionated extraction-elution procedure to prevent breakthrough losses. The developed methods were tested in a validation exercise between five laboratories, which had taken part in the method development, and in an intercomparison between 10 laboratories including laboratories with less experience of vitamin determination. The within-laboratory RSD was generally < or = 11%. The average of the between-laboratory relative standard deviation (RSD) was about 23% in the validation, and increased to about 40% in the intercomparison. Ruggedness tests performed at different steps of the project showed that different types and models of equipment did not give large differences in recoveries. Thus, the increasing RSD can largely be ascribed to differences in experience in vitamin analysis of the participants.

The pharmacodynamics and pharmacokinetics of mivacurium in children

BACKGROUND

In children, onset time and duration of action of mivacurium are shorter than in adults. Some suggest that this is due to differences in plasma cholinesterase (pChe), whereas others indicate that there is no difference. The purpose of this study was to evaluate the pharmacodynamics and pharmacokinetics of mivacurium in phenotypically normal children aged 3-6 and 10-14 years old, respectively.

METHODS

Ten children aged 3-6 years and 10 children aged 10-14 years were studied during halothane anaesthesia. Before induction of anaesthesia, a blood sample was drawn to measure the pChe activity and phenotype. The neuromuscular block was monitored at the thumb using train-of-four (TOF) nerve stimulation every 12 s and mechanomyography. The times to different levels of neuromuscular recovery following mivacurium 0.2 mg/kg were recorded. The concentrations in venous blood of the three isomers and the metabolites of mivacurium were measured.

RESULTS

No statistically significant difference was found in pChe activity or in the pharmacodynamics of mivacurium. The onset time was 1.4 min (0.8-1.9) median (range) and 1.3 min (1.1-1.9) and the time to first response to TOF nerve stimulation was 9.6 min (6.5-12.6) and 10.5 min (7.0-14.0) in young and older children, respectively. The pharmacokinetic data were too sparse to allow analysis of the two age groups separately (8 and 8 patients), hence the data were pooled. The median clearances of the cis-cis, the cis-trans, and the trans-trans isomer were 5.5, 51.0 and 30.5 ml/kg/min, respectively.

CONCLUSION

Our data indicate that there are no major differences in pharmacodynamics or pharmacokinetics of mivacurium between young (3-6 years) and older (10-14 years) children.

Photodynamic effect on cancer cells influenced by electromagnetic fields

The synergism of low-frequency electromagnetic field treatment and photodynamic effect on killing of human cancer cells is presented. The weak pulsating electromagnetic field (PEMF) generated by Helmholtz coils in the mT range influences the permeability of cell membranes for photosensitizers. Several types of sensitizers were excited by visible light during incorporation without and with two kinds of PEMF treatment. In the first part suitable photosensitizers were selected in the absorption range between 400 and 700 nm against human myeloid leukaemia K562 and human histiocytic lymphoma U937 cells by treatment of PEMF consisting of rectangular pulse groups. In the second part amplitude and frequency dependencies were measured using sinuous PEMF and white light with the result that after 12 min the PEMF treatment enhanced photodynamic effectivity by more than 40% over the control value. Taking into account the influence of many parameters, an additional optimization will be possible by photodynamic PEMF synergism for an increased drug delivery in general.

Correlation between detection methods of Chlamydia pneumoniae in atherosclerotic and non-atherosclerotic tissues

Polymerase chain reaction (PCR) and immunohistochemistry (IHC) have been used to detect Chlamydia (C.) pneumoniae in vascular tissues. Discrepancies between the results of these two methods have frequently been reported. However, the correlation between PCR and IHC has not been analyzed yet. This study assesses the correlation between the detection of C. pneumoniae by PCR and IHC in 45 atherosclerotic and 50 non-atherosclerotic tissue specimens. Also, the presence of Mycoplasma (M.) pneumoniae in these 95 specimens was investigated. Correlation was found between the detection of C. pneumoniae by PCR and IHC in the atherosclerotic tissues. Both tests were positive in 10 specimens and negative in 17 specimens (p = 0.003). There was no significant correlation between PCR and IHC in non-atherosclerotic specimens (p = ns). M. pneumoniae was detected, by PCR, in one atherosclerotic specimen.The results show correlation between PCR and IHC in the detection of C. pneumoniae in atherosclerotic tissues, emphasize the association between C. pneumoniae and atherosclerosis, and support the specificity of the association between C. pneumoniae and atherosclerosis.

Visual search and visual working memory in patients with chronic focal cortical lesions

Visually guided behavior is known to involve temporo-parietal, inferotemporal, and prefrontal cortex and each of these areas appears to contribute to visual working memory. We explored the extent to which chronic lesions in one of these cortical areas affect visually guided oculomotor performance. We also explore whether possible impairments become more pronounced with increasing memory load. With this aim we recorded saccadic eye movements in 19 patients with a chronic focal postsurgical lesion in either temporo-parietal, inferior temporal or prefrontal cortex. Their results are compared to those of 19 age-matched volunteers. The subjects performed three different visual search tasks with increasing memory load: Instructed search, cue-guided search and memory-guided search. In addition, the latter task was performed with a short (1 s) and a long (6 s) delay. All tasks required the subjects to make a saccade to a single target presented together with one or three distractors. The results indicate that patients with inferotemporal lesions make the most task-related errors. Saccadic reaction times (SRTs) were significantly prolonged in patients with temporo-parietal and prefrontal lesions, but were unaffected in the patients with lesions in the inferotemporal cortex. The spatial accuracy of saccades was lowest in patients with temporo-parietal lesions. An increase in memory load led to more errors, to longer reaction times and to lower saccadic precision. However, the effect was similar across the three patient groups and the controls. An error analysis indicated that both patients and controls tended to weight global (luminance contrast and form) features higher than local features (line-segment orientation) when making difficult perceptual decisions.

Serum concentrations of carotenoids and vitamins A, E, and C in control subjects from five European countries

High intakes of fruits and vegetables, or high circulating levels of their biomarkers (carotenoids, vitamins C and E), have been associated with a relatively low incidence of cardiovascular disease, cataract and cancer. Exposure to a high fruit and vegetable diet increases antioxidant concentrations in blood and body tissues, and potentially protects against oxidative damage to cells and tissues. This paper describes blood concentrations of carotenoids, tocopherols, ascorbic acid and retinol in well-defined groups of healthy, non-smokers, aged 25-45 years, 175 men and 174 women from five European countries (France, UK (Northern Ireland), Republic of Ireland, The Netherlands and Spain). Analysis was centralised and performed within 18 months. Within-gender, vitamin C showed no significant differences between centres. Females in France, Republic of Ireland and Spain had significantly higher plasma vitamin C concentrations than their male counterparts. Serum retinol and alpha-tocopherol levels were similar between centres, but gamma-tocopherol showed a great variability being the lowest in Spain and France, and the highest in The Netherlands. The provitamin A: non-provitamin A carotenoid ratio was similar among countries, whereas the xanthophylls (lutein, zeaxanthin, beta-cryptoxanthin) to carotenes (alpha-carotene, beta-carotene, lycopene) ratio was double in southern (Spain) compared to the northern areas (Northern Ireland and Republic of Ireland). Serum concentrations of lutein and zeaxanthin were highest in France and Spain; beta-cryptoxanthin was highest in Spain and The Netherlands; trans-lycopene tended to be highest in Irish males and lowest in Spanish males; alpha-carotene and beta-carotene were higher in the French volunteers. Due to the study design, the concentrations of carotenoids and vitamins A, C and E represent physiological ranges achievable by dietary means and may be considered as 'reference values' in serum of healthy, non-smoking middle-aged subjects from five European countries. The results suggest that lutein (and zeaxanthin), beta-cryptoxanthin, total xanthophylls and gamma-tocopherol (and alpha- : gamma-tocopherol) may be important markers related to the healthy or protective effects of the Mediterranean-like diet.

Distribution of DDT residues in fish from the Songkhla Lake, Thailand

Since the early 1950s DDT has been extensively used in Thailand as a malaria repellent and as an agricultural pesticide, but was finally banned in 1994. In this study concentrations of p,p'-DDT, p,p'-DDE, and p,p'-DDD in 113 fish of four species (Scatophagus argus, Protosus canius, Channa striata and Zonichthys nigrofasciata) are reported from the large, brackish Songkhla Lake and the Gulf of Thailand. The mean sigma DDT concentrations at different locations in the analysed fish species ranged from 33 to 170 ng/g lipid wt. (0.086-7.7 ng/g fresh wt.). This is well below the recommended maximum residue levels in aquatic animals used for human consumption (5000 ng/g fresh wt.) in Thailand. The comparatively low residue levels could be due to the high temperature and solar radiation in the region, which may result in a high volatilising and degradation rate of DDT. Also, the high productivity of the lake could result in a dilution effect, when DDT is distributed in a large amount of organic matter, followed by a high biological degradation of the substance.

Biosynthesis of the cyanobacterial reserve polymer multi-L-arginyl-poly-L-aspartic acid (cyanophycin): mechanism of the cyanophycin synthetase reaction studied with synthetic primers

Biosynthesis of the cyanobacterial nitrogen reserve cyanophycin (multi-L-arginyl-poly-L-aspartic acid) is catalysed by cyanophycin synthetase, an enzyme that consists of a single kind of polypeptide. Efficient synthesis of the polymer requires ATP, the constituent amino acids aspartic acid and arginine, and a primer like cyanophycin. Using synthetic peptide primers, the course of the biosynthetic reaction was studied. The following results were obtained: (a) sequence analysis suggests that cyanophycin synthetase has two ATP-binding sites and hence probably two active sites; (b) the enzyme catalyses the formation of cyanophycin-like polymers of 25-30 kDa apparent molecular mass in vitro; (c) primers are elongated at their C-terminus; (d) the constituent amino acids are incorporated stepwise, in the order aspartic acid followed by arginine, into the growing polymer. A mechanism for the cyanophycin synthetase reaction is proposed; (e) the specificity of the enzyme for its amino-acid substrates was also studied. Glutamic acid cannot replace aspartic acid as the acidic amino acid, whereas lysine can replace arginine but is incorporated into cyanophycin at a much lower rate.

Determination of food constituents based on SFE: applications to vitamins A and E in meat and milk

A method has been developed for the determination of vitamins A and E in food using supercritical fluid extraction (SFE), applying liquid or solid trapping, with an accuracy equal to conventional solvent extraction methods. Under optimal conditions, using methanol modified carbon dioxide as a supercritical fluid, Hydromatrix as a water adsorbent, and with a small amount of ascorbic acid and methanol added to the sample, the extraction time is reduced to 80 min. This time is considerably shorter than in conventional methods. Other advantages are the reduction of manual manipulations leading to lower labour costs and reduced consumption of organic solvents in the sample preparation step.

LiMn2O4low-temperature phase: synchrotron and neutron diffraction study

The structural evolution of LiMn2O4spinel was followed from 320 K down to 10 K. The structural transformation, recently studied down to 230 K [Rodriguez-Carvajal, Rousse, Masquelier & Hervieu (1998).Phys. Rev. Lett.81, 4660–4663], takes place near room temperature with a significant hysteresis: the high-temperature cubic phase transforms to a superstructure orthorhombic cell. The present study indicates that the nuclear structure is stable down to 10 K, while neutron diffraction patterns below 80 K show the rise of a magnetic ordering in the spinel phase. From Mn—O bond-length analysis of the MnO6octahedra, a temperature-independent charge ordering in the structure can be deduced.

Examination of the relationship between parameters to determine electropermeability of Saccharomyces cerevisiae

A rectangular electric pulse was applied to Saccharomyces cerevisiae suspensions in NaCl solutions. The relationship between field strength, pulse width and conductivity of extracellular media of key--factors to determine the yield of electropermeability--was examined at the time when the same permeability occurred. The results showed that the dependence of the yield of permeability upon the width of applied pulse was mutually related with the conductivity of extracellular media. Namely at one field strength, the value of pulse width is inversely proportional to that of conductivity of media and its relationship holds true for any field strength. Further, the relationship between parameters considered bears a close resemblance to that recognized between stress amplitude and the number of cycles to failure in the fatigue fracture of materials.

Effects of ELF capacitively coupled weak electric fields on metabolism of 6B1 cells

In this study, we adopted several methods of MTT colorimetry, DAPI fluorimetry and ELISA to study the effects of extremely low frequency (ELF) capacitively coupled electric fields (EFs) on the metabolism of 6B1 cells. The result shows that 50 mV cm(-1) ELF EF (10-100 Hz) has no significant effect on proliferation, DNA synthesis and activity of succinate dehydrogenase of 6B1 cells, indicating that the effect of ELF (10-100 Hz) EF on the metabolism of 6B1 cells is not obvious. However, 50 mV cm(-1), 50 Hz EF significantly promotes the HBs-Ab (Hepatitis B surface antibody) secretion of 6B1 cells, implying that under this situation, EF has some distinctive effect on the outerface of 6B1 cell membrane.

Problems of weak electromagnetic field effects in cell biology

Electrostimulations of cells by weak electric or electromagnetic LF and HF-fields are applied widely today; capacitively or inductively coupled, however, they are seldom applied for cell-free and membrane-free solutions of enzymes. First, the detection of a response of the cells ('electrical window') is a prerequisite for testing at least three parameters: frequency, amplitude and treatment time, besides reproducible biological conditions. The 'state-of-the-art' of this fast developing direction of bioelectrochemistry can be characterized in the following way: the results from several laboratories of (a) cell proliferation, (b) ion transport, (c) activation of several enzymes (Na,K-ATPase), (d) increase of certain protein concentrations (heat-shock protein hsp70) are more or less in agreement. Unfortunately, there are discrepancies between no less than 7 labs in the gene expression of c-myc, c-fos histone 2B, -actin, URA-3 and others, especially for low fields (< 0.05 mT), e.g., in HL60 cells! The reason why seems to be: (1) differences in the most suitable isolation procedure, (2) interferences in the case of too low magnetic flux and (3) too small ranges of parameters have been measured. Today, three open problems must be pointed out: (A) What is the physiological causality for specific 'electrical windows' and their positive or negative efficacy? (B) What are the biochemical targets for either magnetic or electric fields or both? (C) What is the influence of electrical and (or) thermal noise on field efficiency?

Effects of propofol (intravenous propofol emulsion) on cell membranes measured by electrofusion and electroporation

The influence of propofol (CAS 2078-54-8 (intravenous propofol emulsion) on cell membrane properties was investigated in vitro with techniques of cell electrofusion and cell electroporation. Human lymphoma cells and plant protoplasts were chosen as a model system. Propofol (intravenous propofol emulsion) decreased the electrofusion yield of the cells and their membrane permeability. A 50% decrease in relative electrofusion was observed in human lymphoma cells in the presence of about 0.05 mmol/l propofol (intravenous propofol emulsion) and in plant protoplasts in the presence of about 0.1 mmol/l. The fusion of human lymphoma cells was inhibited to 100% at concentrations higher than 0.2 mmol/l propofol and 0.4 mmol/l intravenous propofol emulsion. The membrane permeability of human lymphoma cells decreased by the factor of two with increasing propofol concentrations up to about 0.1 mmol/l. The effects of electroporation were highly reversible. Propofol (intravenous propofol emulsion) was more effective than tetracaine. These sensitive techniques are suitable for the investigation of interactions between anesthetic drugs and the cell membrane.

Tactile evaluation of the response to double burst stimulation decreases, but does not eliminate, the problem of postoperative residual paralysis

BACKGROUND

Routine perioperative monitoring with accelero-myography might prevent residual block, whereas routine tactile evaluation of the response to train-of-four (TOF) nerve stimulation does not. The purpose of this prospective, randomised and blinded study was to evaluate the effect of manual evaluation of the response to double burst stimulation (DBS3.3) upon the incidence of residual block.

METHODS

Sixty adult patients scheduled for elective abdominal surgery were included in the study. Pancuronium 0.08 to 0.1 mg kg-1 was given for relaxation and tracheal intubation. For maintenance of neuromuscular block, pancuronium 1-2 mg was administered. The patients were randomly allocated into two groups. In group DBS (double burst stimulation) the degree of block during anaesthesia was assessed by manual evaluation of the response to TOF nerve stimulation. During reversal, when no fade was detectable in the TOF response, the stimulation pattern was changed to DBS3.3. The trachea was extubated when the anaesthetist judged the neuromuscular function to have recovered adequately and no fade in the DBS3.3 response could be felt. In group CC (clinical criteria) patients were managed without the use of a nerve stimulator, and the level of neuromuscular block and reversal were evaluated solely on the basis of clinical criteria. In both groups, the TOF ratio was measured by mechanomyography immediately after tracheal extubation. Also, the ability to sustain head lift for 5 s, to protrude the tongue, to open the eyes, and to lift one arm to the opposite shoulder were tested.

RESULTS

The TOF ratio, as measured immediately after tracheal extubation, was significantly lower in group CC than in group DBS (means: 0.68 and 0.78, respectively), and the incidence of residual neuromuscular block defined as a TOF ratio < 0.7 was significantly higher in group CC than in group DBS (57 and 24%, respectively). The time from the first TOF measurement until the TOF ratio reached 0.8 was significantly longer in group CC than in group DBs (means: 11.5 and 6.2 min, respectively). No significant differences between the two groups of patients were found in duration of anaesthesia, in times from end of surgery to injection of neostigmine, tracheal extubation or TOF ratio 0.8, in dose of pancuronium, or in any other postoperative variable.

CONCLUSION

Routine perioperative manual evaluation of the responses to TOF and DBS3.3 decreased the incidence and the degree of residual block following the use of pancuronium. It did not, however, exclude clinically significant residual paralysis, nor did it influence the amount of pancuronium used during the operation, the duration of anaesthesia or the time from end of surgery to tracheal extubation or to sufficient recovery of neuromuscular function (TOF = 0.8).

Outbreak of Staphylococcus schleiferi wound infections: strain characterization by randomly amplified polymorphic DNA analysis, PCR ribotyping, conventional ribotyping, and pulsed-field gel electrophoresis

Within a 1-year period, six surgical-site infections (SSI) caused by Staphylococcus schleiferi were observed in the department of cardiac surgery of Ignatius Hospital, Breda, The Netherlands. Since outbreaks caused by this species of coagulase-negative staphylococci have not been described before, an extensive environmental survey and a case control study were performed in combination with molecular typing of the causative microorganism in order to identify potential sources of infection. Variability, as detected by four different genotyping methods (random amplification of polymorphic DNA [RAPD], conventional and PCR-mediated ribotyping, and pulsed-field gel electrophoresis [PFGE] of DNA macro restriction fragments), appeared to be limited both among the clinical isolates and among several control strains obtained from various unrelated sources. Among unrelated strains, RAPD and PCR-mediated ribotyping identified two types only, whereas seven different types were identified in a relatively concordant manner by conventional ribotyping and PFGE. The latter two procedures proved to be the most useful tools for tracking the epidemiology of S. schleiferi. Four of the outbreak-related strains were identical by both methods, and two isolates showed limited differences. In the search for a potential source of S. schleiferi infection, two slightly different PFGE types were encountered on several occasions in the nose of a single surgeon. These strains were, however, clearly different from the outbreak type. In contrast, S. schleiferi cultures remained negative for two persons identified on the basis of case control analysis. It was demonstrated that SSI caused by S. schleiferi had a clinical impact for patients comparable to that of a wound infection caused by Staphylococcus aureus. This report describes the first well-documented outbreak of S. schleiferi infection. A source of the outbreak was not detected.