[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.

Induction of the PAC1-R (PACAP-type I receptor) gene by p53 and Zac

Pituitary adenylate cyclase-activating polypeptides and PAC1-R are expressed during early embryogenesis and PACAP's neurotrophic action supports a role in neuronal development. In the adult brain PACAP functions as a neuroprotective factor that attenuates the neuronal damage resulting from various insults. The tumor suppressor gene p53 and the new zinc finger protein Zac regulate apoptosis and cell cycle arrest through unrelated pathways and both genes are up-regulated under cerebral ischemia. We report here that p53 and Zac induce expression of the PAC1-R gene. By this mechanism p53 and Zac could fine-tune the balance between death promoting and protective signals and may thus fulfil a dual role in ischemia.

Determination of the allergenic activity of birch pollen and apple prick test solutions by measurement of beta-hexosaminidase release from RBL-2H3 cells. Comparison with classical methods in allergen standardization

BACKGROUND

A murine in vitro model of the allergic type I reaction was set up to determine the biologic activity of extracts without involvement of human beings. It is based on beta-hexosaminidase release from passively sensitized RBL cells after allergen challenge. The intended application of this RBL cell assay in the field of quality control of allergenic extracts requires its comparison with established methods.

METHODS

The activity of five standardized birch-pollen prick test solutions was determined in parallel by RBL assay, direct IgE binding, IgE-binding inhibition, major allergen content, histamine-release assay, and skin testing.

RESULTS

The RBL cell-release assay corresponded well to other methods if a reagin raised against natural birch-pollen extract was used for passive sensitization. However, in the case of a reagin against recombinant Bet v 1, only a decreased activity was observed, presumably because a reduced number of epitopes were recognized by the monospecific reagin. In contrast to standardized birch-pollen extracts, nonstandardized apple extracts showed poor activity in all assays.

CONCLUSIONS

This murine model might be a useful tool in the quality control of allergenic extracts. It combines properties of assays based on standardized antisera and of assays that consider IgE cross-linking properties.

[Serum level-adjusted dosage of once-daily aminoglycoside therapy in critical illness: results of a prospective study]

OBJECTIVE

In critically ill patients, the adjustment of target peak and trough levels of tobramycin was investigated because aminoglycoside pharmacokinetics can be changed by multiple influences. Sufficient but not too high peak serum concentrations and low trough levels, however, should be achieved to ensure a therapeutic effect and to minimize toxicity.

METHODS

70 critically ill patients of 51 +/- 18 years were monitored daily during their aminoglycoside treatment on the intensive care unit targeting a peak of about 12 micrograms/ml 30 minutes after infusion and a trough level below 1 to 2 micrograms/ml. Dose recommendations were given daily, taking into consideration serum levels, dose predictions (Bayesian method, ABBOTTBASE), creatinine clearance and clinical findings. Creatinine clearance was estimated according to the Cockcroft-Gault-formula as well as directly by the urine collection method.

RESULTS

The standardized initial dose of 400 mg tobramycin led to average peak serum levels of 14.2 +/- 3.9 micrograms/ml in the patients with an apparent distribution volume of 0.345 +/- 0.074 L/kg. In 95% of the patients, the initial peak was higher than 8.5 micrograms/ml; levels higher than 20 micrograms/ml were observed in 7%, extremely low concentrations (below 5 micrograms/ml) in 2%. With individually adjusted doses between 160 and 560 mg, a mean peak of 11.5 +/- 2.7 micrograms/ml was measured subsequently. The levels amounted to 96 +/- 23% of the predicted values, deviations greater than 50% occurred in 5%. The target trough level was achieved in 99%, in less than 3% the dosing interval was extended up to 72 hours. A tobramycin clearance below 80 ml/min/1.73 m2 was associated with average 80% and 33% higher creatinine clearance values according to the Cockcroft-method and the direct method, respectively.

CONCLUSION

Target peak and trough aminoglycoside levels are adjustable even in critically ill patients. Reduced tobramycin clearance can be associated with normal creatinine clearance. Assuming an exact methodology, a reduced "direct" creatinine clearance, however, indicates a reduced drug clearance.

[Quality of care of patients with diabetes mellitus living in a rural area of Germany]

PATIENTS AND METHOD

In a population based study the quality of diabetes care of insulin-treated diabetic patients aged 16 to 60 years and living in a rural area was studied. The parameters of metabolic control as well as the incidence of acute complications (severe hypoglycemia with the need of glucose or glucagon injection, ketoacidosis with hospital admission) were assessed by examination and with a standardized questionnaire in 81% of the target population (type-1/type-2-diabetic patients: n = 25/33). Also, in all the patients diabetic long-term complications (retinopathy, nephropathy, amputations of the lower extremities) were examined. 76% of the patients with type-1-diabetes and 91% of the patients with type-2-diabetes mellitus completed standardized questionnaires to assess quality of life and treatment satisfaction.

RESULTS

In type-1-diabetic patients HbA1c was 9.38 +/- 1.6%. In type-2-diabetic patients it was 9.53 +/- 1.91%. None of the patients examined was regularly treated by a specialized physician/diabetologist. The goal of metabolic control, a HbA1c value below 7.2%, was reached only by 4% of the patients with type-1-and 12% of the patients with type-2-diabetes mellitus. In multivariate analysis the most important factor associated with HbA1c was in type-1-diabetic patients female sex (R-squared = 0.17, c = 0.38, p = 0.059); in patients with type-2-diabetes mellitus it was the number of insulin injections per day (R-squared = 0.37, c = 0.19, p = 0.0096). All other factors investigated in the model (diabetes duration, insulin dosage/kg body weight, frequency of blood- or urine-glucose self-monitoring/week, body mass index, educational level) showed no significant associations. Quality of life and treatment satisfaction of the patients were good and comparable to other trials.

CONCLUSION

Out of other studies there is evidence for better metabolic control in patients regularly treated by specialized physicians/diabetologists and in patients who participated in structured treatment and teaching programs. These features must be the main goals of treatment for all patients with diabetes mellitus.

Reciprocal connections between the preglomerular complex and the dorsolateral telencephalon in the weakly electric fish, Gymnotus carapo

The diencephalic preglomerular complex of gymnotiform fish receives inputs from several sensory areas. By employing anterograde and retrograde tracing techniques, we studied the afferent and efferent connections of the dorsolateral area (dorsal subdivision) of the telencephalon with the preglomerular nuclei in the weakly electric fish, Gymnotus carapo. Neurons of the medial preglomerular nucleus project to intermediate and deep portions of the middle (commissural) level of the dorsolateral telencephalon, and neurons located in the lateral preglomerular nucleus project to superficial portions of the middle levels of the dorsolateral telencephalon. Therefore, we observed a spatial distribution pattern of connectivity between dorsolateral telencephalon and preglomerular complex.

[Do patients with changes in the vertebral arteries have an increased risk in carotid artery obliteration?]

There was no difference between the groups investigated in terms of the preoperative neurological stages. In patients with VA involvement, both the 30-day mortality rate (p < 0.01) and the long-term survival rate (p < 0.01) were significantly poorer. In the study group, the incidence of shunt procedures was three times as high as in the control group (p < 0.01).

Cross-reactivity and epitope analysis of Pru a 1, the major cherry allergen

A high percentage of birch pollen allergic patients experiences food hypersensivity after ingestion of fresh fruits and vegetables. The cross-reactivity of the major allergens of sweet cherry (Pru a 1), apple (Mal d 1), pear (Pyr c 1), celery tuber (Api g 1) and carrot (Dau c 1) is due to structural similarities which are reflected by high amino acid sequence identities with Bet v 1a, the major birch pollen allergen. Apart from a strong cross-reactivity to Bet v 1a, IgE inhibition experiments with Mal d 1, Pru a 1 and Api g 1 demonstrated the presence of common and different epitopes among the tested food allergens. Secondary structure prediction of all investigated allergens indicated the presence of almost identical structural elements. In particular, the 'P-loop' region is a common domain of the pollen related food allergens and of pathogenesis related proteins. To identify the IgE binding epitopes, five overlapping recombinant Pru a 1 fragments representing the entire amino acid sequence with lengths of approximately 60-120 residues were investigated. Weak IgE binding capacity was measured exclusively with Pru a IF4 (1-120) by immunoblotting, whereas none of the fragments showed allergenicity in the rat basophil leukaemia cell mediator release assay. Site-directed mutagenesis experiments with Pru a 1 revealed that amino acid S112 is critical for IgE binding of almost all patients sera tested. This reduced IgE binding was also observed with a single point mutant of Bet v 1a (S112P) and thus indicated serine 112 as an essential residue for preserving the structure of a cross-reactive IgE epitope. Moreover, two Pru a 1 mutants with an altered 'P-loop' region, showed a lowered IgE binding capacity for IgE from a subgroup of allergic patients. The investigation of essential features for preserving cross-reactive IgE-epitopes provides the structural basis for understanding the clinically observed cross-allergenicity between pollen and fruits. Moreover, non-anaphylactic allergen fragments or variants derived from the IgE-inducing pollen allergens may serve as useful tools for a new strategy of specific immunotherapy.

Recombinant GM2-activator protein stimulates in vivo degradation of GA2 in GM2 gangliosidosis AB variant fibroblasts but exhibits no detectable binding of GA2 in an in vitro assay

The interaction between glycosphingolipids and recombinant human GM2-activator was studied in a microwell binding assay. A-series gangliosides like GM3, GM2 and GM1 were strongly bound by the recombinant human GM2 activator. A weak binding was observed to GD1b and sulfatide, while neutral glycolipids were not bound. Optimal binding occurred at pH 4.2 and was inhibited by increasing concentrations of citrate buffer and NaCl. In contrast with these in vitro results the recombinant human GM2-activator is able to restore the degradation of GA2 in fibroblasts from patients with the AB variant of GM2 gangliosidosis in vivo.

Volatile anaesthetics and the atmosphere: atmospheric lifetimes and atmospheric effects of halothane, enflurane, isoflurane, desflurane and sevoflurane

The atmospheric lifetimes of the halogenated anaesthetics halothane, enflurane, isoflurane, desflurane and sevoflurane with respect to reaction with the hydroxyl radical (OH.) and UV photolysis have been determined from observations of OH. reaction kinetics and UV absorption spectra. Rate coefficients for the reaction with OH radicals for all halogenated anaesthetics investigated ranged from 0.44 to 2.7 x 10(-14) cm3 molec-1 s-1. Halothane, enflurane and isoflurane showed distinct UV absorption in the range 200-350 nm. In contrast, no absorption in this wavelength range was detected for desflurane or sevoflurane. The total atmospheric lifetimes, as derived from both OH. reactivity and photolysis, were 4.0-21.4 yr. It has been calculated that up to 20% of anaesthetics enter the stratosphere. As a result of chlorine and bromine content, the ozone depletion potential (ODP) relative to chlorofluorocarbon CFC-11 varies between 0 and 1.56, leading to a contribution to the total ozone depletion in the stratosphere of approximately 1% for halothane and 0.02% for enflurane and isoflurane. Estimates of the greenhouse warming potential (GWP) relative to CFC-12 yield values of 0.02-0.14, resulting in a relative contribution to global warming of all volatile anaesthetics of approximately 0.03%. The stratospheric impact of halothane, isoflurane and enflurane and their influence on ozone depletion is of increasing importance because of decreasing chlorofluorocarbons globally. However, the influence of volatile anaesthetics on greenhouse warming is small.

Effect of drugs that alter alertness and emotionality on the novelty response of a weak electric fish, Gymnotus carapo

Weak field electric fish respond to alerting stimuli with a transient increase in the frequency of electric organ discharge (novelty response). In an attempt to demonstrate the influence of different degrees of alertness and of emotionality on the novelty response of Gymnotus carapo, we studied the variations in the magnitude of this response induced by the application of an electric stimulus to the water of the experimental box using a pair of electrodes, before and after intramuscular injections of d-amphetamine (1-2 and 4 mg/kg), sodium pentobarbital (10-20 and 30 mg/kg), diazepam (1-2 and 4 mg/kg), beta-carboline (2 mg/kg), and saline. After d-amphetamine injection the animal presented increased somatic motility but no changes in electric organ baseline firing rate or in response to the alerting electric stimulus. Sodium pentobarbital induced a partial loss of posture and a reduction of fin and operculum movements, as well as a reduction of baseline firing rate and of the response to the alerting electric stimulus, with frequent interruptions in electric organ firing. Beta-carboline caused increased motility, but no changes in basal firing rate or in response to the alerting stimulus. Diazepan-injected fishes remained still throughout the experiment, and some of those threated with the higher dose (4 mg/kg) presented interruptions on electric organ discharges in response to stimulation but no change on baseline firing rate. The data suggest that a reduction of the degree of alertness by the barbiturate and a decrease in emotionality and/or stress by the benzodiazepine interfere with the novelty response. The possible site of action of the drugs is discussed.

A melatonin preparation with a pulsatile liberation pattern: a new form of melatonin in replacement therapy

Using melatonin (MLT) as a circadian synchroniser in humans to treat rhythm disorders, it is desirable to have controlled-release dosage forms. Following in vitro liberation tests, one fast-release form containing 5 mg MLT (capsule A) and two oral pulsatile-dosage forms containing 10 mg MLT each (capsules B and C) were studied in a randomised, single-dose, threefold cross-over study in 15 healthy male volunteers after investigation of capsule B in dogs. Mean peak concentrations of MLT in serum (pmol/ml) were reached between 0.5 h and 0.75 h: Cmax1 20.7 (A), 16.4 (B), 9.7 (C). Capsules B and C released a second MLT pulse after about 3.5 h with Cmax2 of 13.0 and 17.5 pmol/ml, respectively. The time course of the renally excreted main metabolite 6-sulphatoxymelatonin (aMT6s) correlates with that of changes in MLT serum concentrations. The kinetic profile of the delivery system is adjusted to the pattern of sleep maintenance disturbances.

LBP-p40 binds DNA tightly through associations with histones H2A, H2B, and H4

Laminin binding protein precursor p40 (LBP-p40) was long believed to be located exclusively in the cytoplasm. We recently reported localization of epitope-tagged LBP-p40 to the nucleus tightly associated with nuclear structure as well as on ribosomes. In this paper, we analyze the interaction of LBP-p40 with DNA and nuclear proteins in vitro. LBP-p40 was found to bind to a double-stranded DNA cellulose column at moderate salt. However, when mixed with a high salt nuclear extract, LBP-p40 was eluted from the DNA cellulose column only at higher salt. An LBP-p40 affinity column indicated that both histone H1 and in particular the core histones associate with LBP-p40. Using recombinant core histone molecules fused with glutathione S-transferase (GST), we demonstrate that histones H2A, H2B, and H4 are capable of interacting with LBP-p40, whereas H3 is not. These results suggest that association of LBP-p40 with histones H2A, H2B, and H4 confers tight binding of LBP-p40 to chromatin DNA in the nucleus.

Induction of type I PACAP receptor expression by the new zinc finger protein Zac1 and p53

We reported recently the cloning of the type I PACAP receptor by a functional expression cloning technique. Unexpectedly, we observed additional PACAP-positive pools that turned out to encode the wild-type form of the tumor suppressor gene p53 and the novel zinc finger protein Zac1, which regulates apoptosis and cell cycle arrest. Both Zac1 and p53 caused, under transient or stably regulated expression, induction of the type I PACAP receptor by transcriptional mechanisms. Transactivation of the type I PACAP receptor gene by Zac1 and p53 points to a subtle balance between death promoting and protective mechanisms. The control of these processes is central to various physiological conditions ranging from development to senescence, whereas dysregulation may lead to overt pathological outcomes, notably cancer, immune deficiency syndromes, and neurodegenerative disorders.

Vasoactive intestinal peptide and epidermal growth factor: co-mitogens or inhibitors of keratinocyte proliferation in vitro?

Vasoactive intestinal peptide (VIP) is a neuropeptide with a broad range of biological activities in various tissues. Interactions of VIP and epidermal growth factor (EGF) are of particular interest for dermatology. They may be either co-mitogenic or inhibitory. HaCaT keratinocytes cultivated under serum-free conditions in vitro have been used to investigate the interactions of VIP and EGF. EGF was found to induce cell growth, whereas preincubation with VIP inhibited EGF-induced proliferation in a dose-dependent manner. Maximum growth inhibition was 46% (p < 0.01) at a VIP concentration of 10(-7) M. EGF-induced growth is mediated by tyrosine kinase (TK). Therefore we studied the effect of VIP on TK activity. Cells were incubated with VIP (10(-13)-10(-7) M) for 48 h and stimulated with EGF at a final concentration of 500 ng/ml. SDS-PAGE and Western blot with the antibody RC20H against TK were performed. We found a dose dependent decrease of EGF receptor TK activity. At VIP concentration of 10(-7) M a residual TK activity of 65% was detected. To investigate the possibly involved signal transduction pathways, we performed inhibition experiments with wortmannin, pertussis toxin, 2'5'diacylglycerol and adenosine-3':5'-mono-phosphorothioate. However, none of the inhibitors was effective in abolishing growth inhibition by VIP. VIP was shown to be growth inhibitory for human keratinocytes. The data suggest that EGF receptor TK is involved in signal transduction of VIP. Thus TK activity is a possible common target of both EGF- and VIP-induced cellular responses.

Bmp-2 downstream targets in mesenchymal development identified by subtractive cloning from recombinant mesenchymal progenitors (C3H10T1/2)

ABmp-dependent in vitro model was used to identify cDNAs during the manifestation of mesenchymal lineages. This model involves the recombinant expression of Bmps (Bmp-2, Bmp-4-7) in murine mesenchymal C3H10T1/2 progenitors, which leads to the differentiation into three lineages: the osteogenic, the chondrogenic and the adipogenic lineage, albeit in varying efficiencies. By subtractive cloning, 21 Bmp-2-regulated cDNAs from C3H10T1/2 mesenchymal progenitors were identified; 20 were related to known sequences and 1 was not. During mouse embryonic development, many of these cDNAs are expressed in chondrogenic, osteogenic, and in adipogenic tissues. Novel findings include a G0/G1 switch gene (G0S2), which was demonstrated to be predominantly expressed in adipose tissue during late murine embryonic development. Furthermore, the membrane-standing glycoprotein autotaxin (ATX) is expressed, at precartilage condensations, joint regions, and during tooth development. An as yet undescribed cDNA, 29A, which encodes a putative secreted factor, is expressed in developing osteo-/chondrogenic tissues of vertebrae, ribs, tooth, and the limb bud. C3H10T1/2-progenitors, therefore, may serve as a legitimate model for the investigation of the Bmp-mediated events during mesenchymal differentiation.

Factors influencing the quality of food extracts for in vitro and in vivo diagnosis

Food extracts for diagnostic purposes often lack sufficient activity and consistency. Biologically standardized food extracts are not available on the market. Using extracts from plant-derived foods as examples, we investigated factors which may be important for the quality of such extracts. Divergent allergenic activities were found between strains of apples, but not within varieties of celery tuber (celeriac), hazelnut, and peanut, respectively. Heating of the food remarkably reduced the activity of apple, hazelnut, and celeriac, but had little effect on peanut. By contrast, heating of semipurified protein extracts from celery tuber and apple for 30 min at 100 degrees C did not deplete the immunoreactivity of the major allergens, indicating that this is an inappropriate test for identifying labile food allergens. Due to their high endogenous enzyme activities, apples and other fruits require special extraction procedures applying either low temperature or enzyme inhibitors. Variation of extraction conditions had little effect on the composition and activity of extracts from hazelnut. The storage stability of skin test solutions from plant foods can be improved by avoiding phenol as an additive and by including 50% of glycerol. For model studies considering neoallergens, IgE was raised in mice against native and heated celery tuber, respectively. When extracts from nonthermally and thermally processed celeriac were subjected to an RBL-cell mediator release assay with these sera, an inverse ranking was obtained with anti-heated celeriac IgE and anti-native celeriac IgE, respectively. These data indicated that new epitopes had been formed by the heating process. Since all parameters were tested in model experiments with either human or murine IgE, their relevance has to be proven in further clinical investigations.

[Computer-based determination of stereopsis]

AIM

A computer-based approach to assess stereopsis for screening purposes is described. This approach is based on random-dot stereograms (RDS).

METHOD

The TNO test is a common method to assess stereopsis based on red/green anaglyphs and the use of RDS. This technique was transferred to a computer-based platform. To investigate the validity of the computer-based approach, 25 subjects were tested with both the TNO test and the computer-based approach.

RESULTS

With regard to the spectral emission of the monitor screen, accurate separation of red and green for RDS generation was not possible. However, adaptation of the RDS to the colour filters used permitted the best-possible separation. The resolution of the monitor required a viewing distance of 2 m. The results obtained showed no significant differences between the two methods.

CONCLUSIONS

For the computer-based screening, RDS and anaglyphs can be employed. The influence of the spectral emission of the monitor screen and its resolution can be reduced by adapting the RDS colours to the filters used and modifying the viewing distance.

Can oral contraceptive steroids influence the elimination of nifedipine and its primary pryidine metabolite in humans?

OBJECTIVE

To investigate the influence of oral contraceptives on cytochrome P450 3A4 (P450NF) activity.

METHODS

In 23 healthy women, the pharmacokinetics of nifedipine and its main metabolite dehydronifedipine in plasma were assessed after a single oral dose, prior to and after intake of one of two oral contraceptive formulations, one containing 2 mg dienogest and 0.03 mg ethinylestradiol (group A) and the other containing 0.125 mg levonorgestrel and 0.03 mg ethinylestradiol (group B).

RESULTS

While the intake of two oral contraceptives for 21 days did not influence the plasma concentration-time curve of unchanged nifedipine, mean AUC0-23.5 h and the mean Cmax values of dehydronifedipine were significantly lower in both groups tested/(24% in group A and 25% in group B). This observation may indicate a reduced formation rate of metabolites and reflects an inhibition of cytochrome P450 3A4 activity. The activation of the same or other metabolic degradation mechanism(s) could explain this result.

CONCLUSION

The investigation presented demonstrates the importance of metabolite measurement when in vivo studies are undertaken to investigate different influences on drug metabolizing ability.

Stereotaxic atlas of the telencephalon of the weakly electric fish Gymnotus carapo

A restraining box for the head and body of the electric fish Gymnotus carapo was constructed and coupled to a micromanipulator, permitting us to prepare an atlas of the telencephalon with stereotaxic parameters. A photograph and a schematic drawing of an animal's head is presented, showing two skin electroreceptors that were used as external landmarks. A sagittal section of the telencephalic structure is also presented, whose vertical bars indicate the frontal planes that compose the atlas. The frontal planes of the atlas consist of serial sections spaced 600 or 500 microns apart in the rostrocaudal axis. Sections mapped with acetylcholinesterase are shown, intercalated with Nissl-stained sections. The acetylcholinesterase sections proved to be useful for the delimitation of certain nuclei and for the exact localization of small fissures and fiber tracts. A brief description of major cytoarchitectural subdivision and connections of the telencephalon is provided.