Late conduction defects following aortic valve replacement

BACKGROUND AND AIM OF THE STUDY

The study aim was to determine the incidence and clinical significance of late cardiac conduction defects (CD) after aortic valve replacement (AVR).

METHODS

An analysis was made of 100 consecutive cases after AVR in a prospective outpatient evaluation program.

RESULTS

The perioperative (30-day) mortality rate was 5%, and incidence of perioperative pacemaker implantation 3%. Among patients, 19% had CDs before surgery; a normal ECG was present during all periods in 45% of patients. The most frequent perioperative CD was left anterior hemiblock (LAHB; n = 8), and the most frequent late CD was left bundle branch block (LBBB; n = 8). Overall, 13.7% of operative survivors with normal preoperative and perioperative ECGs developed late CDs; one patient (1%) required pacemaker implantation 82 months after AVR. A further three patients (3%) had worsening of pre-existent CDs. Late CDs occurred over a wide time range (3 to 102 months) after surgery.

CONCLUSION

There is an important incidence of CDs that occur late after AVR, even if the perioperative ECGs are normal; however, a need for late pacemaker implantation is rare. As CDs may occur at any time after surgery, regular follow up with precise evaluation of ECGs is called for.

Effect of the dry-cold season dormancy on the tonic and phasic neural control of heart rate in the toad, Bufo paracnemis

This work examined basal heart rate and autonomic cardiac tone as well as sympathetic cardiac reactivity to hypotension induced by systemic nitroprusside injection in dormant toads (dry-cold season), Bufo paracnemis, comparing the values with those of toads collected during the active months (hot-rainy season). Autonomic tone was calculated according to the method of Lin and Horwath ('72), which allows its evaluation as a percentage of intrinsic heart rate. Specimens were maintained in an outdoors terrarium except for the week preceding surgery, when they were transferred to indoor nonclimatized tanks. The heart rate of dormant toads (27.8 +/- 2.7 beats/min) was lower than that of active toads at rest (38.6 +/- 2. 3). Cholinergic tone was higher than adrenergic tone both in active (26.2% and 7.8%, respectively) and aestivated (19.5% and 4.8%, respectively) animals. Thus, cholinergic tone and adrenergic tone were both lower in dormant animals. The reflex tachycardia elicited by nitroprusside-induced hypotension was lower in aestivated toads (9.3 +/- 0.9 beats/min) when compared to active toads (19.9 +/- 1.0), indicating a reduced sympathetic reactivity. Nitroprusside-induced hypotensions were not different in the two groups. We conclude that at rest Bufo paracnemis heart is under the influence of a double cholinergic and adrenergic tone, and that both influences, as well as the reflex adrenergic reactivity to the unloading produced by nitroprusside-induced hypotension, are reduced in aestivated toads.

Micromanipulation by laser microbeam and optical tweezers: from plant cells to single molecules

Complete manipulation by laser light allows precise and gentle treatment of plant cells, subcellular structures, and even individual DNA molecules. Recently, affordable lasers have become available for the construction of microbeams as well as for optical tweezers. This may generate new interest in these tools for plant biologists. Early experiments, reviewed in this journal, showed that laser supported microinjection of material into plant cells or tissues circumvents mechanical problems encountered in microinjection by fragile glass capillaries. Plant protoplasts could be fused with each other when under microscopical observation, and it was no major problem to generate a triple or quadruple fusion product. In the present paper we review experiments where membrane material was prepared from root hair tips and microgravity was simulated in algae. As many plant cells are transparent, it is possible to work inside living, intact cells. New experiments show that it is possible to release by optical micromanipulation, with high spatial resolutions, intracellular calcium from caged compounds and to study calcium oscillations. An example for avian cardiac tissue is given, but the technique is also suitable for plant cell research. As a more technical tool, optical tweezers can be used to spatially fix subcellular structures otherwise moving inside a cell and thus make them available for investigation with a confocal microscope even when the time for image formation is extended (for example at low fluorescence emission). A molecular biological example is the handling of chromosomes and isolated individual DNA molecules by laser microtools. For example, chromosomes can be cut along complex trajectories, not only perpendicular to their long axis. Single DNA molecules are cut by the laser microbeam and, after coupling such a molecule to a polystrene microbead, are handled in complex geometries. Here, the individual DNA molecules are made visible with a conventional fluorescence microscope by fluorescent dyes such as SYBRGreen. The cutting of a single DNA molecule by molecules of the restriction endonuclease EcoRI can be observed directly, i.e. a type of single molecule restriction analysis is possible. Finally, mechanical properties of individual DNA molecules can be observed directly.

Lack of association between 27-bp repeat polymorphism in intron 4 of the endothelial nitric oxide synthase gene and the risk of coronary artery disease

The gene encoding endothelial nitric oxide synthase (ecNOS) is a candidate gene for the mediation of initial endothelial cell damage seen in arteriosclerosis. Although the association of ecNOS polymorphisms with hypertension has been studied extensively, there is little information regarding its association with coronary artery disease (CAD). We decided to study a 27 base-pair tandem repeat polymorphism in intron 4 of the ecNOS gene in 1043 individuals (413 controls, 630 patients with CAD) who consecutively underwent coronary angiography at our institution. The frequencies of the genotypes drawn from 1038 individuals were 0.69, 0.28 and 0.03 in the controls and 0.73, 0.25 and 0.02 in individulas with CAD for the ecNOS4b/b, ecNOS4b/a and ecNOS4a/a genotypes, respectively (p = n.s). There was no shift of the genotype frequencies from the expected distribution based on the Hardy-Weinberg equilibrium. Neither the rare ecNOS4a allele nor the ecNOS4a/a genotype conferred an independent risk factor for CAD in subgroups, e.g. smokers, diabetic individuals, hypertensive individuals and individuals with a low conventional risk for CAD. In five individuals we identified an additional 27-bp repeat in the ecNOS gene (ecNOS4c), which occurred heterozygous with the ecNOS4b allele (ecNOS4b/c genotype). In conclusion, the ecNOS4a allele as well as the ecNOS4a/a genotype did not show a general association with CAD in the studied European population. Even in high-risk subgroups the ecNOS4a/4a genotype did not represent an independent risk factor for CAD. In addition, the severity of CAD was not associated with the ecNOS4a allele/ecNOS4a/a genotype.

Baroreceptor control of heart rate in the awake toad: peripheral autonomic effectors and arterial baroreceptor areas

Systemic injection of sodium nitroprusside (30 microg/kg, i.v.) in the awake Bufo paracnemis toad induced a fall in arterial blood pressure and tachycardia. This tachycardia, but not the hypotension, was significantly reduced in toads with bilateral electrolytic lesion of the caudal and commissural regions of the solitary tract nucleus and in animals with transection of the spinal cord, 2 mm below the obex. This indicates that the tachycardia is reflex, depends on the integrity of the solitary tract nucleus and is due to descending spinal autonomic activation. Pretreatment with propranolol (4 mg/kg, i.v.) significantly reduced the tachycardia but did not block it completely, showing the importance of beta-adrenoceptors in its genesis. The reflex increase in heart rate induced by nitroprusside was not statistically significant in animals with bilateral section of the laryngeal nerve, whose baroreceptor fibers originate from the pulmocutaneous artery or in animals in which the bilateral section of the laryngeal nerve was performed together with section of the glossopharyngeal nerves, which incorporate fibers originating from the carotid labyrinth. The reduction of the reflex tachycardia was significant in toads with aortic arch denervation alone or combined with section of the laryngeal nerves or in animals with complete denervation of the three baroreceptors areas. These results suggest that the region of the aortic arch, when submitted to unloading, is the most important baroreceptor zone for cardiac compensation in toads.

Five cases with central diabetes insipidus and hypogonadism as first presentation of neurosarcoidosis

OBJECTIVES

We retrospectively reviewed 5 patients with neurosarcoidosis, who all presented with central diabetes insipidus and hypogonadism.

DESIGN

This was a single-centre, retrospective analysis of 5 cases with a minimum follow-up of 2 years.

METHODS

Case analysis included clinical, biochemical, and endocrinological evaluation and frequent CT/MRI scans of involved organs as primary evaluation and in response to immunosuppressive therapy.

RESULT

Neurosarcoidosis was diagnosed in all patients. Two patients had no proven extracerebral manifestation and had a stable disease over 3 and 5 years. One patient showed deterioration with corticosteroids alone but partial remission after additional cyclophosphamide. Pituitary dysfunction remained unchanged in all patients, despite total clinical and radiological remission in two patients. However, one of these patients died of acute granulomatous meningoencephalitis after two years of follow-up.

CONCLUSION

Although the presenting symptoms of neurosarcoidosis may vary, the occurrence of central diabetes insipidus associated with typical radiological features is suggestive of neurosarcoidosis. However, there is an increasing number of case reports on lymphocytic hypophysitis. Without the bioptic diagnosis, the differentiation between potentially lethal isolated neurosarcoidosis and lymphocytic hypophysitis is difficult. These cases demonstrate the difficulties in diagnosing neurosarcoidosis and reflect experiences with follow-up parameters.

Combined assessment of obstructive sleep apnea syndrome with dynamic MRI and parallel EEG registration: initial results

RATIONALE AND OBJECTIVES

To detect obstructive pharyngeal changes in sleeping patients with obstructive sleep apnea syndrome by dynamic MRI and concurrent EEG monitoring during true apneic episodes.

METHODS

Five volunteers and eight patients with clinically diagnosed obstructive sleep apnea were polysomnographically monitored inside the scanner before, during, and after sleep discontinuation. After sleep interruption, the Mueller maneuver was performed to compare induced pharyngeal collapse with real collapse during sleep.

RESULTS

In all patients, on-line EEG registration was achieved in the static magnetic field. Sleep was proved in four of the eight patients who showed typical EEG findings. A complete pharyngeal collapse was shown in two of the four sleeping patients. The other patients predominately showed local epi- and oropharyngeal obstructions in the apneic state. Compared with the apneic episodes, the Mueller maneuver did not reveal the same extent of pharyngeal narrowing, nor a complete collapse.

CONCLUSIONS

Polysomnographically monitored MRI can directly assess findings induced by the pathophysiology of sleep apnea and shows promise for use in sleep investigation and therapy planning and monitoring.

Electromyography in MRI--first recordings of peripheral nerve activation caused by fast magnetic field gradients

Prior studies on the evaluation of stimulation by MRI were based on the subjective feeling of the volunteers. A wide variety of stimulation thresholds between the subjects was observed. In order to exclude subjective perception levels as a cause of this variation, we developed a method to investigate the activation of peripheral nerves after gradient switching by electromyography (EMG) within the MR-imager. Five healthy volunteers were positioned in the MR-scanner with the bridge of the nose at isocenter. The amplitude of sinusoidal pulse trains of the anterior-posterior gradient (rise-times: 200 or 300 micros, various numbers of oscillations) was increased stepwise. Four surface electrodes were placed on the region where a muscle-twitch was reported. Electric activity of the muscle during stimulation experiments was recorded with an MR-compatible electro-physiologic amplifier. Stimulation thresholds were defined by the appearance of an EMG-signal. Thresholds were sharp and consistent with the report of the subjects.

First clinical data of a natural immunomodulator in colorectal cancer

BACKGROUND/AIMS

MSC (trade-name AVEMAR) is a per os applicable complex of multiple, biologically active molecules obtained from fermented wheat-germ extract. Preclinical studies suggest potent anti-metastatic activity and it has a favorable toxicity profile. It has been aimed in a pilot-scale, phase II clinical study to document whether or not MSC as a support to surgery or plus chemotherapy adds any therapeutic benefit compared to the same combination without MSC in colorectal cancer.

METHODOLOGY

From 1998 to June 1999, 18 control patients and 12 consecutive colorectal cancer patients respectively, were enrolled into this study. All patients underwent curative surgery. The control group (18 patients) received no other therapy or adjuvant chemotherapy alone. The MSC group (12 patients) received MSC alone or plus adjuvant chemotherapy. Until now, the median follow-up has been 9 months.

RESULTS

Interim data of the study document that in the MSC group no new metastases, neither hepatic nor other, have occurred, so far. On the contrary, several new metastases have developed in the control group.

CONCLUSIONS

Orally administered MSC is a potent candidate to be regarded as a supportive therapy to surgery or plus chemotherapy for colorectal cancer patients.

Cardiac allograft vascular disease after orthotopic heart transplantation: methylenetetrahydrofolate reductase gene polymorphism C677T does not account for rapidly progressive forms

BACKGROUND

Recently, homocysteine (HCY) levels have been suggested to be a risk factor in cardiac allograft vascular disease (CAVD). As plasma levels are partially under genetic control, we investigated the influence of the methylenetetrahydrofolate reductase (MTHFR) polymorphism on HCY levels and development of CAVD in heart transplant (HTX) recipients.

METHODS

Genotyping and assessment of fasting HCY levels were performed in a cohort of 146 HTX recipients and correlated to the onset and progression of CAVD, assessed by serial angiography.

RESULTS

Actuarial freedom from CAVD did not differ significantly between the genotypes. However, patients positive for CAVD presented with higher HCY levels than CAVD-negative individuals (21.0+/-9.4 vs. 18.2+/-6.6 micromol/L, P=0.046).

CONCLUSIONS

There is some evidence that plasma HCY might be involved in development of CAVD. However, polymorphism of the MTHFR gene could not be shown to be related to severity of allograft vascular disease.

[Therapy of osteoporosis: strategies for individualized treatment]

Pharmacological and non-pharmacological interventions are available and useful for effective treatment of osteoporosis. Drugs act by stimulation of bone formation (fluoride) or inhibition of bone resorption (calcium, vitamin D compounds, bisphosphonates, hormone replacement therapy, calcitonin). Published data for effectiveness on bone mineral density and/or fracture rates vary considerably. Non-pharmacological interventions to prevent falls or the impact of falls (hip protectors) must be part of a sufficient treatment strategy. Costs of treatment have to be considered in comparison to costs of fracture repair and rehabilitation.

A Combined Experimental and Theoretical Investigation of the Reactions of 3-Pentoxy Radicals: Reaction with O2 and Unimolecular Decomposition

The reactions of 3-pentoxy radicals with O

In addition to the experimental investigation, the unimolecular reaction channels of 3-pentoxy radicals were also analyzed by a combined

Analysis of point mutation in exon 2 of CYP2E1 gene in renal cell/urothelial cancer patients in comparison with control population

OBJECTIVE

Genetic polymorphisms of human cytochrome P450s have been implicated to be of importance for susceptibility to different cancers. Recently, a point mutation was found in the exon 2 of the CYP2E1 gene (CYP2E1*2) [Hu et al. 1997]. In order to evaluate a possible link between the point mutation in exon 2 of the CYP2E1 gene and the susceptibility to renal cell/urothelial cancer, we developed a screening method based on the polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP).

MATERIAL

DNA of peripheral white blood cells was isolated from 158 renal cell/urothelial cancer patients as well as from 150 controls.

METHOD

Primers for PCR were designed by the Primer 3 release 0.1 program. The PCR yield a product of 215 base pairs (bp), which was digested with the restriction enzyme Hha I. The DNA fragments were separated on a 3% agarose gel stained with ethidium bromide. Restriction enzyme digestion of the PCR product obtained from the wild-type DNA resulted in the appearance of a 66 bp, a 43 bp, a 40 bp, a 39 bp and a 28 bp DNA fragment. In contrast to the wild-type, the digestion of the PCR product from DNA carrying the point mutation resulted in the loss of the 39 bp and 40 bp fragments and the appearance of an additional 79 bp fragment. Therefore, the loss of one Hha I restriction site caused by a single nucleotide exchange is suitable for the identification of the point mutation in exon 2 of CYP2E1 gene.

RESULTS

However, we could not detect any point mutation in any of the 158 renal cell/urothelial cancer patients or the 150 controls. The distribution of the point mutation in exon 2 of CYP2E1 gene did not show any difference in renal cell/urothelial cancer patients and controls.

CONCLUSION

This might indicate a lack of association between this CYP2E polymorphism (CYP2E1*2) and renal cell/urothelial cancer.

A common variant of the angiotensinogen gene and the risk of coronary artery disease in a German population

The thymidine to cytosine transition at position 704 in exon 2 of the angiotensinogen gene leads to the amino acid substitution of threonine for methionine (T235 variant) and is responsible for elevated plasma levels of angiotensinogen. To examine the influence of T235 on the risk of coronary artery disease (CAD) we genotyped 184 CAD patients, 77 controls in whom CAD was excluded angiographically, and 155 healthy controls without signs of CAD by polymerase chain amplification and restriction enzyme digestion. Allele frequencies for A (wildtype) and a (mutant allele) in the total study population were 0.538 and 0.462, 0.536 and 0.464 in the healthy controls, and 0.481 and 0.519 in patients with excluded CAD, respectively. The allele frequencies and the genotype distribution in these groups did not show a significant difference. In conclusion, we did not observe an association between the T235 variant of the angiotensinogen gene and the risk of CAD.

Molecular cloning and characterization of a birch pollen minor allergen, Bet v 5, belonging to a family of isoflavone reductase-related proteins

BACKGROUND

Birch pollen is a major cause of pollinosis and is responsible for cross-reactive oral allergies to fruits, nuts, and vegetables. The major allergen, Bet v 1, has been extensively characterized, and 3 minor allergens, Bet v 2, Bet v 3, and Bet v 4, have been cloned and sequenced. Recently, another birch pollen protein with an apparent mass of 35 kd was described as a new IgE-binding protein in birch pollen with cross-reacting homologues in plant foods.

OBJECTIVE

The aim of this study was to determine the primary structure of the 35-kd birch pollen allergen and to investigate its immunologic properties.

METHODS

On the basis of a known complementary DNA fragment, a PCR strategy was applied to obtain the full-length nucleotide sequence of the coding region. The protein was expressed as His-Tag fusion protein in Escherichia coli and purified by Ni-chelate affinity chromatography. Nonfusion protein was obtained by cyanogen bromide treatment of the fusion protein. IgE-binding characteristics and potential allergenicity were investigated by immunoblot, immunoblot inhibition analysis, rat basophil leukemia-cell mediator release assay, and basophil histamine release and compared with those of natural (n) Bet v 5, recombinant (r)Bet v 1, and rBet v 2.

RESULTS

Recombinant Bet v 5 has a mass of 33 kd, an isoelectric point of 9.0, and sequence identity of 60% to 80% to isoflavone reductase homologue proteins from various plants. On immunoblots the recombinant Bet v 5 bound IgE from 9 (32%) of 28 sera from patients allergic to birch pollen with a CAP class of at least 3; Bet v 1 was detected by 89% of these patients. IgE immunoblot and inhibition experiments showed that nBet v 5 and rBet v 5 shared identical epitopes. A rabbit antiserum raised against pea isoflavone reductase and patients' IgE reacted with Bet v 5 and proteins of similar size in several vegetable foods, including exotic fruits. A similar reaction pattern was obtained with 2 Bet v 5-specific mAbs. Furthermore, Bet v 5 triggered a dose-dependent mediator release from rat basophil leukemia 2H3 cells passively sensitized with murine anti-birch pollen IgE and from basophils of a Bet v 5-reactive subject with birch pollen allergy. In contrast, no mediator release could be induced from basophils of a subject who was monosensitized to Bet v 1.

CONCLUSIONS

This 33-kd protein, designated as Bet v 5, is a new minor allergen in birch pollen and may be responsible for pollen-related oral allergy to specific foods in a minority of patients with birch pollen allergy. Amino acid sequence comparison and immunoreactivity to anti-isoflavone reductase serum indicate that Bet v 5 is related to isoflavone reductase, a protein family that is involved in plant defense reactions.

Fate of plasmid-bearing, luciferase marker gene tagged bacteria after feeding to the soil microarthropod Onychiurus fimatus (Collembola)

In order to study the potential impact of the soil microarthropod Onychiurus fimatus (Collembola) on the microbial community, we analysed the fate of luciferase marker gene tagged bacterial strains fed to young adult specimens in petri dish microcosm experiments. In faeces collected from O. fimatus, Escherichia coli S17-1/pRP4luc and Sinorhizobium meliloti L33 were only detectable for 2 days after feeding whereas strain HR2/pRP4luc, a close relative of Stenotrophomonas maltophilia, isolated from another collembolan species, could be detected for 16 days. The amount of shed cells of strain HR2 increased during the frequent releases of the cast-off skins (exuvia). In order to analyse whether gut associated bacteria could serve as recipients for mobile genetic elements, plasmid-bearing E. coli donor strains were incubated with faeces in filter mating-like experiments and, in other experiments, directly fed to O. fimatus specimens. Transconjugants were obtained with both the conjugative self-transferable broad host range plasmid pRP4luc and the mobilisable (Mob(+)) broad host range plasmid pSUP104luc, the latter, however, only with a mobilising donor strain. No transfer was detected with the narrow host range plasmids pSUP202luc (Mob(+)), pUC18luc (Mob(-)), or with the broad host range transposon delivery plasmid pUTluxCDABE (Mob(+)). Transconjugants of pRP4luc were detected within one day of the beginning of a feeding experiment and then throughout the incubation period of two weeks, with gaps of no detection after 5, 12 and 14 days, probably caused by moulting. The results of this study indicate that feeding activities of collembola can modify the structure of soil-inhabiting microbial communities and enhance the spread of plasmids from non-indigenous to indigenous soil bacteria.

[Success and complication rates of diagnostic and therapeutic endoscopic retrograde cholangiopancreatography--a prospective study]

The aim of the prospective study was to evaluated the efficacy and the complications of 2,820 ERCP-examinations in 1,717 consecutive patients (performed over a three-year period). The rate of success was 82.8% for diagnostic ERCP, 96.6% for endoscopic sphincterotomy, 76.8% for the extraction of stones on common bile tract, 87.5% for drainage in bile tract obstruction, respectively. The rate of all complications amounted to 7.9% (4.9% diagnostic ERCP, 9.2% therapeutic ERCP, in detail: 3.8% acute pancreatitis, 2.1% cholangitis, 1.3% bleeding, 0.2% perforation, 0.5% other respectively). The total mortality was 0.1% (three cases of death). The frequency of complications increased with the number of procedure at the papilla Vateri in patients, who underwent needle knife papillotomy in combination with standard papillotomy.

Pollen-related food allergy: cloning and immunological analysis of isoforms and mutants of Mal d 1, the major apple allergen, and Bet v 1, the major birch pollen allergen

BACKGROUND

Mal d 1, the major apple allergen, cross-reacts with IgE specific for the major birch pollen allergen, Bet v 1, and is responsible for birch pollen related food allergy to apple. Isoforms of Bet v 1 showing minor sequence variations display different binding capacity for specific IgE antibodies from allergic patients. Moreover, strain-dependent variation of allergenicity has been reported for apples.

OBJECTIVE

To investigate the occurrence of strain-dependent isoforms of Mal d 1 which may differ in their allergenic potential, to obtain data on structures essential for binding of Mal d 1 to the antibody, and to gain insights into the structures responsible for its IgE cross-reactivity to Bet v 1.

METHODS

The cDNA of Mal d 1 from various apple strains was amplified by a PCR strategy based on conserved regions of known Mal d 1-sequences, and sequenced. Two major isoforms of Mal d 1 were expressed as recombinant proteins and purified, as were different variants of the major birch pollen allergen, Bet v 1. Together with already existing recombinant birch pollen and apple allergens, these were subjected to allergenicity testing by IgE-immunoblotting, enzyme allergo sorbent test and dose related mediator release. "Hot-spots" for IgE-reactivity were identified by site-directed mutagenesis.

RESULTS

Twelve Mal d 1-clones were sequenced from 7 apple varieties and compared to 3 known Mal d 1 sequences. The clones were clustered into two groups, each showing a high degree of sequence identity to one of the known sequences and specific differences to the third sequence. No strain-specific sequences were identified. In contrast, apple strains with reported differences in allergenicity showed different expression levels of the major allergen. Immunologic testing of recombinant allergens revealed high IgE binding capacity of 2 major isoforms, named GD26 and GS29, with a slightly higher IgE binding capacity of GD26. Moreover, the allergenicity was similar to another r Mal d 1 reported in the literature, representing the isoform divergent from our clones. Mutational analysis of our Mal d 1 allergens identified serine in position 111 as essential for IgE binding. Allergenicity was almost depleted by changing this residue into a proline. Moreover, the corresponding serine residue, present in position 112 of Bet v 1, was in a similar manner crucial for the allergenicity of the birch pollen allergen.

CONCLUSION

We conclude that divergent allergenicity of apple strains mainly depends on different expression levels of the major allergen. Introduction of a proline residue in position 111 of Mal d 1 and in position 112 of Bet v 1 led to a drastic reduction of allergenicity of both the pollen and the food allergen, obviously also removing the cross-reactive epitope. Mutants with reduced IgE-reactivity but maintained T-cell reactivity may represent new candidates for a safer specific immunotherapy with reduced side-effects.

Analysis of volatile organic compounds in human urine by headspace gas chromatography-mass spectrometry with a multipurpose sampler

A multipurpose sampler (Gerstel MPS), designed for liquid large volume, gaseous and headspace samples was used for the GC-MS analysis of organic volatiles in human urine. Headspace sampling with a volume-, temperature- and speed-controlled gas-tight syringe was combined with a temperature-controlled cold injection system (CIS) for cold trapping, enrichment and focusing of analytes. Regular 2-ml GC vials filled with 1 ml acidified urine were used as headspace sampling vials. A 100-vial autosampler tray was equipped with an additional temperature and heating time controlled "preheating station" for five vials. Profiles of organic volatiles in human urine were determined and 34 components identified. Trimethylamine (TMA) and 4-heptanone as two metabolites of medical interest were quantified. Calibration curves and intra assay imprecision for 4-heptanone concentrations in the range of 40 to 800 ng/ml showed a correlation coefficient of r = 0.9980 and a relative standard deviation (RSD) between 3.0 and 3.4%. Calibration curves and intra-assay imprecision for TMA concentrations in the range of medical interest from 0.5 to 20 micrograms/ml showed a correlation coefficient of r = 0.9968 and a RSD between 4.1 and 6.8%. The high practicability of the multipurpose sampler for both gaseous and liquid samples together with the here shown good reproducibility and sensitivity make this single CIS-GC-MS system very attractive for routine clinical use in metabolic profiling of organic volatiles (headspace) and non-volatiles (liquid).

Identification of plasticizers in medical products by a combined direct thermodesorption--cooled injection system and gas chromatography--mass spectrometry

The combination of a new thermodesorption module with a cooled injection system now provides a powerful system for direct analysis of volatile trace compounds in gaseous, liquid and solid samples by gas chromatography-mass spectrometry (GC-MS). As a cooled injection system is used for the cryofocusing of the desorbed volatiles the GC-MC system still can be used for the regular analysis of liquid samples. Although plasticizers usually are analyzed by GC-MS after solvent extraction, contaminated solvents and glassware are very well known problems. Analysis of plasticizers in plastic materials by direct thermodesorption instead saves time and avoids cross contaminations. Many medical products are made of plasticized polyvinyl chloride. Extraction of the common plasticizer di(2-ethylhexyl) phthalate (DEHP) into blood will occur, and harmful effects of DEHP in the human body have been suggested. We therefore analyzed 21 different plastic devices which are used for various invasive techniques in medicine by direct thermodesorption GC-MS. In some of the plastics up to 30 different components were identified. By far the most common plasticizer found was DEHP, followed by diethyl and dibutyl phthalates.

[Recurrent ventricular fibrillation in a patient with Prinzmetal angina pectoris--case report]

The description of the case of 35 years old patient with paroxysmal ventricular fibrillation in a course of Prinzmetal angina pectoris treated unsuccessfully with antiarrhythmic drugs who required implantation of cardioverter/defibrillator. The via-venous cardioverter/defibrillator was implanted (ICD). During 6 months observation ventricular tachycardia and ventricular fibrillation occurred four times and was effectively interrupted by the cardioverter/defibrillator.