A novel sequential procedure to enhance the renaturation of recombinant protein from Escherichia coli inclusion bodies.
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Animals↗
Biomedical subjects
B Fischer
Publications and source records attributed to B Fischer.
Sense and antisense transcripts of human papillomavirus type 16 in cervical cancers.
Human papillomavirus type 16 (HPV-16) transcription was analysed in one squamous cervical carcinoma by cDNA cloning and DNA sequencing, and in eight additional squamous cervical carcinomas and 11 precancerous lesions by RNA-RNA in situ hybridization. The nucleotide sequences of the cDNA clones revealed structures of early HPV-16 mRNAs (E6*-E7-E1 E4-E5) in agreement with data reported for other premalignant and malignant tumours. cDNA clones possibly representing viral RNA of antisense orientation were also detected. These RNAs included sequences of the upstream regulatory region, part of the early and the late region of the genome. In three of eight squamous cervical carcinomas examined by in situ hybridization, signals specific for viral antisense RNA were also found. The antisense RNAs had a predominantly nuclear localization. Viral antisense RNA could not be detected in any of 11 HPV-16-positive premalignant lesions. The expression of HPV antisense RNA is likely to be linked to viral integration into the host genome. The possible effects of viral antisense transcription with regard to tumour progression remain to be determined.
Female↗
Electrogram patterns predictive of successful radiofrequency catheter ablation of accessory pathways.
UNLABELLED: We assessed anterograde conduction electrogram parameters at successful ablation sites according to accessory pathway (AP) location and compared them to the most favorable electrograms at unsuccessful sites. A median of three radiofrequency energy impulses was applied to ablate 97% of 136 APs versus four impulses to ablate 90% of 65 concealed APs. Electrograms at successful sites showed variable A/V ratio (0.04-7), and a QS pattern of unipolar ventricular wave in 90%. Electrograms were different in right versus left AP: AV time 29 +/- 7 versus 38 +/- 10; and timing of ventricular deflection: 17 +/- 9 versus 2 +/- 9 msec, respectively. Analysis in each patient of the mapping parameters at successful versus "most favorable" unsuccessful sites showed an improvement in at least one parameter in 55%, no apparent change in all parameter values in 30%, and even less favorable parameters in 15% of patients. In patients with manifest AP, overall comparison of electrograms at successful versus unsuccessful sites showed no difference in A/V ratio (1.3 +/- 1.5 vs 1.2 +/- 1.6), unipolar pattern distribution, and AV time (34 +/- 10 vs 35 +/- 9), but earlier bipolar main ventricular potential (-4 +/- 12 vs -1.5 +/- 10 msec) and unipolar intrinsic deflection timings (-5.2 +/- 11 vs -1.8 +/- 10 msec). In patients with concealed AP, a retrograde continuous electrical activity was recorded in 72% of successful versus 38% of unsuccessful sites (P = 0.03). CONCLUSIONS: Electrogram characteristics at successful radiofrequency ablation are different in right and left manifest AP.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Elimination of atrioventricular nodal reentrant tachycardia using discrete slow potentials to guide application of radiofrequency energy.
BACKGROUND: Ablation of the slow pathway has been performed to eliminate atrioventricular (AV) nodal reentrant tachycardia (AVNRT) either by a surgical approach or by using radiofrequency catheter technique guided by retrograde slow pathway activation mapping. From previous experience of midseptal and posteroseptal mapping, we were aware of the existence of peculiar slow potentials in most humans. Postulating their role in AVNRT, we studied these potentials and the effects of radiofrequency energy. METHODS AND RESULTS: Sixty-four patients (mean age, 48 +/- 19 years) with the usual form of AVNRT were studied. Slow, low-amplitude potentials were recorded when using the anterograde AV conducting system. Slow potentials occupied all (giving a continuum of electrograms) or some of the time between the atrial and ventricular electrograms. Their most specific patterns were their progressive response to increasing atrial rates, which resulted in a dramatic decline in amplitude and slope, a corresponding increase in duration, and a separation from preceding atrial potentials until the disappearance of any consistent activity. Slow potentials were recorded along a vertical band at the mid or posterior part of the septum near the tricuspid annulus. Radiofrequency energy applied at the slow potential site resulted in interruption of induced tachycardia within a few seconds and rendered tachycardia noninducible in all patients. A median of two impulses was delivered to each patient. In 69% of patients, postablation atrial stimulation cannot achieve a long atrial-His interval, which previously was critical for tachycardia induction or maintenance. No patient had AVNRT over a follow-up period of 1-16 months, and all had preserved AV conduction. In all except two patients, the PR interval was unchanged. In 47 patients, long-term electrophysiological studies confirmed the efficacy of ablation and the nonreversibility of results by isoproterenol; however, echo beats remained inducible in 40% of patients. CONCLUSIONS: An area showing slow potentials is present at the perinodal region in humans. In patients with AVNRT, application of radiofrequency energy renders tachycardia noninducible through the preferential modification of the anterograde slow pathway. With present clinical methods, the exact origin and significance of these physiological potentials cannot be specified.
Cardiac Pacing, Artificial↗
Radiofrequency catheter ablation of left lateral accessory pathways via the coronary sinus.
BACKGROUND: The purpose of this study was to describe a new technique for catheter ablation of left lateral accessory pathways (APs) by radiofrequency energy applied at the epicardium through the coronary sinus wall using a unipolar configuration. METHODS AND RESULTS: In an overall group of 212 patients with left lateral APs, multiple endocardial ablation attempts of the AP were unsuccessful in eight patients. The mean +/- SD cumulative duration of previous attempts was 12 +/- 9 hours, using DC shocks and/or radiofrequency energy applied both at the atrial and/or ventricular AP insertions. Epicardial AP insertion was determined by bipolar and unipolar unfiltered distal electrograms by scanning the coronary sinus with a steerable 6F or 7F catheter with a 4-mm distal electrode. The local atrial to ventricular electrogram amplitude ratio was 0.3-1.6. At the ablation site, the catheter tip was slightly deflected toward the annulus to increase both the ventricular component of electrograms and contact with the epicardium. In four patients, epicardial electrogram timings were earlier than endocardial ones. The AP was ablated in seven of the eight patients with 20-30 W applied for 10-60 seconds. No complications occurred except a marked nonspecific pain during radiofrequency energy application; however, the catheter remained adherent to the coronary sinus wall, and its withdrawal was performed during a new radiofrequency application to decrease the risk of coronary sinus rupture. After ablation, echocardiograms, coronary artery angiograms, and levophase coronary sinus angiograms showed no abnormality in all patients except two who had a probable mural thrombus in the coronary sinus. AP conduction remained abolished for 1-10 months of follow-up in seven patients. CONCLUSIONS: Radiofrequency catheter ablation of left lateral APs can be achieved effectively and relatively safely via the mid or distal coronary sinus when endocardial approaches are unsuccessful.
Catheter Ablation↗
Isolation and renaturation of bio-active proteins expressed in Escherichia coli as inclusion bodies.
Over-expression of recombinant proteins in Escherichia coli often results in the formation of insoluble and inactive material as inclusion bodies. Within the last years specific methods and strategies have been developed to produce bio-active proteins from these inclusion bodies. These methods include (i) isolation and purification of inclusion bodies, (ii) solubilization and reduction of the insoluble material, and (iii) renaturation of the proteins including formation of native disulphide bonds. Inclusion bodies are isolated from E. coli cells after desintegration of cells by mechanic forces. Due to their stability, inclusion bodies may be purified by washing with detergent solutions or low concentrations of denaturant. High concentrations of urea and guanidine hydrochloride are used in combination with reducing reagents such as 2-mercaptoethanol or dithiothreitol to reduce and solubilize proteins from inclusion bodies. After purification of solubilized materials, proteins are renatured and native disulphide bonds are formed by either air oxidation or glutathione reoxidation starting from reduced material, or by disulphide interchange starting from mixed disulphides containing peptides. Final yield of renatured proteins is raised by low concentrations of proteins and by adding low concentrations of denaturant during renaturation.
Animals↗
[Focal junctional tachycardia in adults. Anatomo-electrophysiological aspects apropos of a case].
The authors report the case of a 65 year old patient with focal junctional tachycardia complicating infectious myocarditis which had a fatal outcome. The ECG recordings showed episodes of tachycardia alternating with junctional rhythm at 90/min. There were signs of retrograde conduction. The anatomopathological findings were typical of acquired myocarditic lesions in the lower part of the atrioventricular node with congenital abnormalities, in particular a bifid node and His bundle with an accessory paraseptal atrioventricular bundle. This is the first description, to the best of the authors's knowledge, of junctional tachycardia associated with a latent pre-excitation.
Aged↗
[Radiofrequency treatment of junctional tachycardia].
Atrioventricular nodal tachycardias due to intranodal reentry or to an accessory pathway are accessible to radical cure with radiofrequency currents applied either at the site of recording of characteristic slow potentials or at the tricuspid or mitral atrioventricular rings. One hundred and six patients with atrioventricular nodal reentry were treated by modification of the slow anterograde reentrant pathway with a 100% success rate and without any serious complications (especially atrioventricular block). One hundred and eighty six patients had one or more overt or latent accessory pathways and were treated by the same method. The ablation site was decided on indirect criteria and not by the recording of the specific activity of the accessory pathway. The success rate was 97%, also with no significant complications. The duration of the treatment was 41 +/- 22 min for the accessory pathways. The exposure time to ionising radiation was 14 +/- 14 min and 31 +/- 34 min respectively. These results suggest that the indications of radiofrequency current ablation could be extended.
Adolescent↗
[Anthroposophically oriented pediatric nursing].
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Anthroposophy↗
The dynamic structure of rabbit blastocyst coverings. III. Transformation of coverings under non-physiological developmental conditions.
Under physiological conditions the zona pellucida disappears in the rabbit between Day 3 and early Day 4 post coitum (p.c.) and is replaced by a new layer, the neozona. The dissolution of the zona pellucida and the formation of the neozona was investigated in three different experimental approaches, all of them characterized by non-physiological developmental conditions for the embryo: Prevention of embryo migration from the oviduct into the uterus by postcoital (48 h p.c.) tubal ligation, in vitro culture, and asynchronous embryo transfer into uteri of recipient rabbits. Embryos of age 2 1/2, 3, 4 and 4 1/2 days p.c. were cultured for 12 to 72 h. The media used for in vitro culture were supplemented with BSA, serum or with uterine secretions that were collected either synchronously or asynchronously to the developmental stage of the cultured embryos. Three-day-old embryos were transferred into uteri of pseudopregnant foster rabbits of either synchronous (Day 3) or asynchronous stages (Day 0, 2, 4, 5, 6) and were recovered 24 to 72 h after transfer. The transformation of the coverings was evaluated by light and transmission electron microscopy. The dissolution of the zona pellucida was greatly disturbed in tube-locked embryos, and in cultured embryos if standard protein supplements (BSA or serum) had been used for in vitro culture. In many cases the zona was still completely preserved after 2 or 3 days in culture, at a time when it normally would have already been replaced by the neozona in vivo. The dissolution in vitro, however, progressed incomparably better if the culture medium had been substituted with synchronous or asynchronous uterine secretions. The formation of the neozona could not be verified in cultured blastocysts. After embryo transfer, the dissolution of the zona pellucida was completed in most cases by 2 days after transfer, irrespective of the recipients' progestational stage. Present results indicate that uterine components are essential for the dissolution of the rabbit zona pellucida. These components appear to be present in the uterine cavity constitutively, i.e. independently of the uterine progestational transformation, and need not be in synchrony with the embryo's developmental stage for dissolution of the zona. Normal formation of the neozona does not take place under the non-physiological developmental conditions of in vitro culture.
Animals↗
Effects of visible light and room temperature on the ultrastructure of preimplantation rabbit embryos: a time course study.
In a time course study (4-20 h) rabbit early cleavage stages (day 1 p.c.) and compacted morulae (day 3 p.c.) were exposed to visible light or room temperature (23 degrees C), respectively. An 8 h light exposure of day 1 embryos caused alterations in nuclear morphology (lobulated nuclei, loss of nucleolar differentiation), an increased electron density of the cytoplasm, and cellular fragmentation leading to a considerable degeneration of blastomeres (central clustering of organelles, loss of cell surface differentiation) after a 20 h exposure. Room temperature exposure (compacted Day 3 morulae) led to decompaction and a cleavage delay after 8 h. After 10 h, arrested metaphases occurred in all examined morulae. Even after 20 h at 23 degrees C, day 3 embryos were at the decompacted morula stage, and showed metaphase-arrested blastomeres. The general morphology of the blastomeres was unaffected at this temperature, except for vacuolated ser- and cis-side vesicles of the Golgi complex at 8, 12 and 20 h, respectively.
Animals↗
Occurrence of express saccades under isoluminance and low contrast luminance conditions.
Saccadic reaction times (SRTs) of three human subjects were analyzed. The gap paradigm was used (i.e. fixation point offset precedes target onset) to obtain high proportions of express saccades (i.e. saccades of extremely short reaction times) in the SRT distributions. In one set of experiments, the luminance of the (red) saccade target was varied from brighter to darker than the (green) background including an isoluminance condition. Express saccades were obtained in response to pure color contrast stimuli with about the same frequency and reaction time as to stimuli with both color and luminance contrast. In a second experiment, the luminance contrast of a white target on a white background was lowered below 10%. Again the number of express saccades was not reduced. Thus, in contrast to other perceptual phenomena the visual neural mechanisms underlying the generation of express saccades are not affected by isoluminance nor low contrast luminance.
Color Perception↗
Trunk orientation as the determining factor of the 'contralateral' deficit in the neglect syndrome and as the physical anchor of the internal representation of body orientation in space.
The present study examines which egocentric coordinate system determines the border between the disturbed 'contralateral' and the normal 'ipsilateral' side in patients with hemineglect. Based on the observation of significantly longer reaction times for saccades towards stimuli presented in the left visual field (LVF) in right brain-damaged patients with hemineglect, stimuli were presented randomly to the LVF or RVF and the corresponding saccadic reaction times (SRTs) were compared. Beginning with the standard body position generally used for the investigation of neglect patients, where the midlines of head, trunk and visual field are parallel and oriented straight towards the middle of the projection screen, the spatial relation between orientation of head and trunk midlines and location of the target stimuli was systematically varied while holding the retinal projection of the stimuli constant. The deficit in SRTs towards the LVF in 4 right brain-damaged patients with left-sided hemineglect could be compensated for by turning the patients' trunk to the left, such that both LVF and RVF-stimuli were projected to the right, ipsilateral side of trunk space. The results suggest that the spatial orientation of the trunk midline divides our normal perception of space into an egocentric 'left' and an egocentric 'right' sector and seems to be the decisive factor for determining the neglected 'contralateral' part of space in patients with brain-damage. They indicate that the trunk midline constitutes the physical anchor for calculation of the internal egocentric coordinate frame for representing body position with respect to external objects. The hypothesis of Ventre et al. (1984) that deficient reactions to contralaterally located stimuli in neglect patients could be the result of a displacement of these egocentric coordinates towards the non-neglected, ipsilateral side is discussed.
Adult↗
Effects of monoclonal antibodies on tissue-type plasminogen activator (t-PA) binding to lysine, fibrin and heparin and on fibrin-mediated enhancement of one-chain t-PA amidolytic activity.
The effects of 4 monoclonal antibodies against human tissue-type plasminogen activator (t-PA) on binding of t-PA to lysine, fibrin, and heparin, and on fibrin-mediated activation of one-chain t-PA-amidolytic activity were investigated. The association constants of the antibodies were determined in a direct assay to be equal to 0.125 l/nmol, 0.225 l/nmol, 0.4 l/nmol, and 0.5 l/nmol for mAB 5, mAB 16, mAB 25, and mAB 31, respectively. All 4 monoclonal antibodies inhibited binding of intact t-PA to lysine-Sepharose and fibrin, and they suppressed fibrin-mediated activation of one-chain t-PA-amidolytic activity. Binding analysis demonstrated that mAB 25 inhibited t-PA binding to lysine-Sepharose and to fibrin as well as fibrin-mediated enhancement of one-chain t-PA-amidolytic activity in a competitive manner with inhibitor constants of 5 nmol/l, 3 nmol/l and 10 nmol/l, respectively. It was also shown that free lysine counteracts the association of t-PA with the antibodies. Binding of t-PA to heparin is only moderately affected by the 4 antibodies. Since t-PA possesses two homologous kringle domains which contain fibrin (lysine) binding sites, the results underline the importance of a lysine binding site for fibrin binding by intact t-PA and show that the binding of the enzyme to fibrin and lysine is mediated by the same binding site of a kringle domain. The parallel effects of antibodies on fibrin binding and on fibrin-mediated enhancement of one-chain t-PA amidolytic activity proves that the site of fibrin binding is identical with the site of fibrin activation. The binding site of heparin apparently differs from lysine and fibrin binding sites.
Antibodies, Monoclonal↗
Embryonic development and incidence of aneuploidy in two rabbit strains of different fecundity.
The correlation between strain fecundity and (i) development and (ii) rate of aneuploidy was studied in rabbit preimplantation embryos obtained from 2 strains of different fecundity. Embryos were investigated at Days 3-6 (preimplantation development) or Days 2, 4 and 6 post coitum (aneuploidy). Embryonic size and cell proliferation varied on the days of investigation, but with no consistent tendency in favour of one strain. The incidence of aneuploidy did not differ significantly between embryos from the 2 strains (P greater than 0.05). The multifactorially determined criterion of prolificacy was not selectively correlated with overall differences in embryonic preimplantation growth and rate of aneuploidy.
Aneuploidy↗
Binding of one-chain tissue-type plasminogen activator to fibrin, partially plasmin-degraded fibrin, lysine and heparin.
Tissue-type plasminogen activator (t-PA) binds to heparin with an association constant of 2.4 x 10(4) l/mol at pH 7.4. The binding increases at lower pH-values and reaches maximal values below pH 6.0. Sodium chloride above 0.5 mol/l abolishes t-PA binding to heparin at neutral pH. t-PA binds to lysine maximally at pH 6 to pH 9. At neutral pH the association constant is 1.8 x 10(5) l/mol. Sodium chloride concentrations of 1 mol/l reduce interaction of the enzyme to lysine by about 60% at pH 7.4. Binding of t-PA to fibrin and to partially plasmin-degraded fibrin takes place maximally at pH 6 to 9. The interaction of t-PA with plasmin-degraded fibrin is less sensitive to addition of lysine than the interaction of t-PA and fibrin. Sodium chloride concentrations of 1 mol/l reduce the interaction of t-PA to fibrin by about 60% at pH 7.4.
Chromatography, Agarose↗
Development of a BaF2/TMAE PET system.
A detector has been developed for position sensitive registration of annihilation radiation. The 511 keV gamma rays are detected in a set of BaF2 scintillation crystals coupled to low pressure TMAE-filled photosensitive multi wire chambers. In a first experimental detector with two BaF2 crystals we obtained a detection efficiency for 511 keV quanta of 42%. The position resolution is 5 mm and the time resolution is 4 ns. At present a circular detector for three BaF2 crystals with a diameter of 28 cm, each with a thickness of 8 mm, is under construction. Position sensitivity is obtained by means of delayline read out of cathode wires. Detectors of this type can be used as building blocks for a PET system. We are performing simulations of a system consisting of six rectangular detectors in a hexagonal composition. Results are given and a discussion of further innovative developments is presented.
Barium↗
[Diabetes insipidus in sarcoidosis].
Sarcoidosis is a generalized disorder which involves the central nervous system in 5 per cent of patients presenting with the disease. We describe the case of a 22-year-old man who developed central diabetes insipidus with a daily urine production of 14,81 seven weeks after diagnosis of pulmonary sarcoidosis and parotid gland enlargement. Computed tomography showed a contrast enhancement of pituitary gland and stalk, no other intracranial manifestations were demonstrated. Intranasal administration of synthetic antidiuretic hormone (ADH) reduced urine volume to normal levels immediately. After discontinuation of 15 months therapy with corticosteroids and administration of ADH for 29 months spontaneous urine volume didn't exceed 31. The patient has been free of symptoms since discontinuation of therapy.
Administration, Intranasal↗