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Biomedical subjects

C Kessler

Publications and source records attributed to C Kessler.

At least 127 records · Page 7Linked to original sources
PubMed1992

Sensitive chemiluminescent detection of digoxigenin-labeled nucleic acids: a fast and simple protocol and its applications.

A fast and simple protocol for the chemiluminescent detection of digoxigenin-labeled nucleic acids with anti-digoxigenin antibody Fab fragments coupled to alkaline phosphatase and 3-(4-methoxyspiro[1,2-dioxetane-3,2'-tricyclo-[3.3.1.1 (3,7)]decan]-4- yl)phenyl phosphate as substrate is described. The washing and blocking procedure was optimized to yield low background even on positively charged nylon membranes. The sensitivity of the system is equal or better than radioactive methods. Exposure to x-ray or Polaroid film for up to 30 minutes is sufficient for the detection of 70 femtograms of homologous DNA. Human single-copy genes are detected in Southern blots of as low as 0.3 microgram total placental DNA. Blots can be reprobed multiple times very easily. The advantages of the digoxigenin system are high sensitivity, absence of background and ease of reprobing and are illustrated by applications for single-copy gene detection in genomic blots of human DNA, Northern hybridizations to rare mRNA, detection of E. coli genes on blots of genomic digests after pulse field gel electrophoresis, as well as for nonradioactive DNA sequencing blots with digoxigenin-labeled primers.

Actins↗
PubMed1991

EEG power variation in schizophrenic subgroups: effects of emotionally salient stimuli.

Eighteen unmedicated chronic schizophrenic patients and 13 normal controls were tested in a paradigm designed to examine functional changes in electroencephalographic (EEG) activity following presentation of emotionally salient auditory stimuli and control tones. Five standard bands of EEG spectral power were examined at bilateral frontal and temporal surface recording sites. The schizophrenic subjects were assigned to diagnostic subgroups on the basis of DSM-III-R criteria following independent clinical examination by two staff psychiatrists. Those subjects who met DSM-III-R criteria for paranoid schizophrenia were assigned to one subgroup (PS subgroup), while those who met DSM-III-R criteria for either residual or undifferentiated schizophrenia were assigned to a second subgroup (R/US subgroup). Analysis of Variance of EEG activity recorded at bilateral frontal (F1 and F2) and temporal (T3 and T4) scalp leads revealed significant diagnosis-related differences in alpha and beta-2 activity at temporal recording sites, and in beta-1 and beta-2 activity at frontal recording sites. Post-hoc tests revealed that significant differences in all four measures occurred in the R/US subgroup, which showed a decrease in temporal alpha and an increase in temporal beta-2 power as compared to controls. These variations in EEG activity appeared to demonstrate a degree of subgroup specificity, as the R/US subgroup also differed significantly from the PS subgroup on most of these measures. Significant subgroup-specific lateralization effects were also observed for temporal lobe delta activity and for frontal lobe beta-1 activity. These findings are interpreted in terms of subgroup-specific alterations in the processing of sensory information in schizophrenia, particularly when such information is emotionally salient. They suggest that subgroup differences in emotional and clinical state may be reflected in differential changes in EEG spectra within the schizophrenic population.

Acoustic Stimulation↗
PubMed1991

A complex family of class-II restriction endonucleases, DsaI-VI, in Dactylococcopsis salina.

A series of class-II restriction endonucleases (ENases) was discovered in the halophilic, phototrophic, gas-vacuolated cyanobacterium Dactylococcopsis salina sp. nov. The six novel enzymes are characterized by the following recognition sequences and cut positions: 5'-C decreases CRYGG-3' (DsaI); 5'-GG decreases CC-3' (DsaII); 5'-R decreases GATCY-3' (DsaIII); 5'-G decreases GWCC-3' (DsaIV); 5'-decreases CCNGG-3' (DsaV); and 5'-GTMKAC-3' (DsaVI), where W = A or T, M = A or C, K = G or T, and N = A, G, C or T. In addition, traces of further possible activity were detected. DsaI has a novel sequence specificity and DsaV is an isoschizomer of ScrFI, but with a novel cut specificity. A purification procedure was established to separate all six ENases, resulting in their isolation free of contaminating nuclease activities. DsaI cleavage is influenced by N6-methyladenine residues [derived from the Escherichia coli-encoded DNA methyltransferase (MTase) M.Eco damI] within the overlapping sequence, 5'-CCRYMGGATC-3'; DsaV hydrolysis is inhibited by a C-5-methylcytosine residue in its recognition sequence (5'-CMCNGG-3'), generated in some DsaV sites by the E. coli-encoded MTase, M.Eco dcmI.

Base Sequence↗
PubMed1991

Rapid filter assay for the detection of DNA polymerase activity: direct identification of the gene for the DNA polymerase from Thermus aquaticus.

A method for rapid identification of DNA polymerase activity employing an activated DNA substrate covalently bound to nitrocellulose membranes is described. Samples containing DNA polymerase are spotted and the membranes are incubated in an appropriate polymerization buffer containing radioactively labelled dNTPs. By autoradiography of the dried filters, DNA polymerase activity can be directly identified. The method can be used for fast and large-scale screening of chromosomal expression libraries for heterologous DNA polymerases characterized by activity optima different from those of the host organisms. We have identified the gene of the thermostable DNA polymerase from Thermus aquaticus in an expression library of Escherichia coli.

Cell Membrane↗
PubMed1991

Influence of the strength, drop size and viscosity of metipranolol eye drops on the concentration of the substance in human aqueous humour.

Concentrations of metipranolol were determined in the aqueous humour of patients undergoing cataract surgery. At 30 min before the operation, patients were given 20- or 30 microliters drops of 0.1% or 0.3% metipranolol solutions with a viscosity of 7.5 cP or drops (20 or 30 microliters) of a 0.3% solution with a viscosity of 1.5 cP. Samples of the aqueous humour were obtained at the beginning of the cataract operation, and desacetyl-metipranolol content was determined by means of gas chromatography and mass spectroscope. The Wilcoxon signed-rank test and Jonckheere's method were used for evaluation of the results. A 3-fold increase in the strength of metipranolol was associated with an approx. 8-fold increase in the concentration of metabolite found in the aqueous humour. Drop size had no apparent effect on the concentration of this substance in the aqueous humour, but viscosity had a significant influence when large drops were applied. An increase in the amount of metipranolol applied as eye-drops was associated with an increase in the intraocular concentration of the metabolite.

Administration, Topical↗
PubMed1991

Influence of the concentration of metipranolol eye drops on the drug concentration in human aqueous humour.

The concentration of the metabolite of the beta-blocker metipranolol was determined in the aqueous humour of 89 cataract patients. At 1, 2 or 5 h before surgery, they received one drop (30 microliters) of a 0.1% or 0.3% solution of the drug. At 1, 2 or 5 h after the application of 0.1% metipranolol eye drops, desacetyl-metipranolol concentrations of 624.55, 235.29 and 88.02 ng/ml, respectively, were measured. At the same intervals after the instillation of 0.3% metipranolol eye drops, the respective values of 1289.20, 1120.88 and 327.36 ng/ml were found. The metabolite concentration in the eye drops and the values measured show no consistent correlation.

Adrenergic beta-Antagonists↗
PubMed1991

Colour Doppler flow imaging of the carotid arteries.

53 patients with carotid artery atherosclerosis were examined by colour Doppler flow imaging. These results were compared with real time duplex sonography and continuous wave Doppler sonography. In 48 low degree stenoses (less than 50%) the B-mode showed 36 smooth and 12 ulcerated plaque surfaces. In 24 high degree stenoses (greater than 50%) 10 plaques were smooth and 14 ulcerated. In the low degree stenoses, which exhibited smooth surfaces in B-mode examination, colour flow Doppler showed nine additional cases with turbulences in the area of the stenotic site. This indicates that plaque ulcerations in low degree stenoses are underestimated. In contrast, in nearly all cases with high degree stenoses marked turbulences could be demonstrated by colour Doppler flow imaging independent of the B-mode, showing regular or ulcerated plaque surfaces. Additionally, the duplex ultrasound diagnosed a carotid artery occlusion in 11 cases, but the colour coded Doppler was able to assess a remaining blood flow in two out of these 11 cases. Our results suggest that the colour Doppler flow imaging as a noninvasive technique is an advantage in diagnosing plaque ulcerations and it is more precise in diagnosing carotid occlusions than duplex-sonography is.

Arteriosclerosis↗
PubMed1991

Nonradioactive labeling of oligonucleotides in vitro with the hapten digoxigenin by tailing with terminal transferase.

A procedure for the nonradioactive labeling of oligonucleotides with the hapten digoxigenin (DIG) has been developed. The label is introduced by enzymatic tailing of the 3'-end. Two different modified nucleotides were applied. DIG-dUTP allows the synthesis of hapten-modified oligonucleotides with longer tails containing several DIG molecules, whereas the novel compound DIG-ddUTP leads to the addition of only a single DIG hapten. The efficiency of the labeling reactions with respect to variation of the different parameters was analyzed and data on application of labeled oligonucleotide probes to different blot formats are shown.

Biotin↗
PubMed1991

The digoxigenin:anti-digoxigenin (DIG) technology--a survey on the concept and realization of a novel bioanalytical indicator system.

A review is given on the novel non-radioactive digoxigenin:anti-digoxigenin (DIG) bioanalytical indicator system. After a general introduction on direct and indirect indicator systems based on previous non-radioactive indicator reactions as well as in vitro and in vivo amplification procedures the principle of the new digoxigenin:anti-digoxigenin technology is demonstrated. The novel system is based on the specific high-affinity interaction between the cardenolide digoxigenin from Digitalis plants and a digoxigenin-specific antibody coupled with a reporter group. A variety of methods for digoxigenin modification of nucleic acids, proteins and glycans are presented. In addition, various applications of the novel non-radioactive indicator system in a variety of direct or indirect detection approaches with either insoluble or soluble substrates are described. It is also shown that with these applications alternative reaction formats are used which are partly characterized by additional amplification steps.

Antibodies↗
PubMed1991

Doppler CO2-test in patients with vertebrobasilar ischemia.

The pathogenesis of vertebrobasilar ischemia (VBI) is still uncertain. Embolism and systemic hypotension have been discussed as possible causes. We evaluated the basilar arteries of 35 VBI-patients by transcranial Doppler-sonography at rest and under hypercapnic conditions and compared these findings with the basilar flow velocities in 10 healthy volunteers matched by age. We found no difference between the controls and the VBI-patients for the basilar flow velocities at rest. Under hypercapnia (end-tidal CO2-concentration 8.5%), the basilar blood flow velocities in the healthy controls increased by an average of 53.0% but only by 32.3% in the VBI-patients (p less than 0.005). The reduction of CO2 dependent vasomotor reactivity was observed in all VBI-patients, except in patients with infarction in the posterior cerebral artery area, possibly indicating a different pathogenic mechanism of stroke. The results in all other patients revealed no obvious correlation to the clinical course or angiographic or dopplersonographic findings. As CO2 dependent vasomotor reactivity and brain perfusion pressure dependent cerebral autoregulation have similar mechanisms, we conclude that systemic hypotension might play an important part in VBI.

Aged↗
PubMed1991

Clinical relevance of intraplaque hemorrhage in the internal carotid artery.

In this study the correlation between hemispherical ischemic symptoms and the presence of intraplaque hemorrhage in carotid plaques has been evaluated. 38 patients who had undergone carotid endarterectomy were examined clinically and the specimens obtained from operation were studied morphologically. The patients were divided into two groups, asymptomatic and symptomatic regarding the territory of the supplying carotid artery. The presence of intraplaque hemorrhage, shown by Ladewig's Trichrom stain, as well as evidence of iron, immunohistochemical stain of hemoglobin and native fluorescence microscopy was noted, and, according to their extension, classified into three degrees. As a result, there was neither a correlation between history of ischemic brain symptoms and the presence of intraplaque hemorrhage, nor between clinical symptoms and extension of hemorrhage. The plaques were high degree stenotic (greater than 80%) in most of the patients and showed various degenerative changes. In 97% of all plaques with hemorrhages surface defects were seen. Our results confirm that intraplaque hemorrhage is one out of a series of pathological events which occurs during advanced atherosclerosis. Blood inflow from the lumen through an already damaged plaque surface is a common event and a correlation with the onset of symptoms is unlikely.

Arteriosclerosis↗
PubMed1991

Unresectable pancreatic cancer: what is the optimal procedure?

We retrospectively reviewed cases of pancreatic cancer to determine the benefit of various methods of biliary decompression and the role of prophylactic gastroenterostomy (GE) in management. Twenty-seven patients had only biliary bypass, and 26 had biliary bypass and GE. Operative mortality was similar for both groups (22% and 19%, respectively). The complication rates were almost identical (37% and 35%). Differences in operative mortality, incidence of cholangitis, and recurrence of jaundice were not statistically significant between patients having biliary decompression via the common bile duct or the gallbladder. Operative mortality associated with choledochoenterostomy was 33% versus 17% for cholecystoenterostomy. Gastric outlet obstruction developed in 5% of patients who did not have GE. We conclude that cholecystojejunostomy is an effective method of biliary bypass. Because its addition did not seem to increase operative morbidity or mortality, we advocate GE at the initial exploration to prevent gastric outlet obstruction.

Aged↗
PubMed1990

Non-radioactive labeling of RNA transcripts in vitro with the hapten digoxigenin (DIG); hybridization and ELISA-based detection.

We have developed a system for the enzymatic in vitro synthesis of non-radioactively labeled RNA which is derivatized with the hapten digoxigenin (DIG). The labeling reaction as well as the conditions for hybridization and detection of hybrids by an antibody-conjugate and a coupled colour reaction were analyzed and adapted for high sensitivity and low background. In addition, data on the performance and sensitivity of digoxigenin-labeled RNA probes in Southern and Northern blots are presented.

Animals↗
PubMed1990

Cloning, expression and characterization of the Sau3AI restriction and modification genes in Staphylococcus carnosus TM300.

The genes encoding the restriction enzyme (ENase) and modification enzyme (MTase) of Staphylococcus aureus 3A (recognition sequence 5'-GATC-3') have been cloned in Staphylococcus carnosus TM300 using the vector pCA44. Clones carrying both genes were isolated from DNA libraries prepared with MboI + BamHI. The DNA region encoding M.Sau3AI was subcloned on a 3.66-kb EcoRV fragment in vector pT181mcs. Plasmids purified from the clones were resistant to digestion with Sau3AI, indicating that the sau3AIM gene was expressed and the product was functional in S. carnosus. Cell lysates of clones with both activities encoded on plasmid pSEM7, cut DNA with the same pattern as Sau3AI, showing that the sau3AIR gene was also expressed and the ENase was functional in S. carnosus. Sequence analysis shows that both genes are transcribed in the same direction and encode polypeptides with calculated Mrs of 56,477 for R.Sau3AI and 47,300 for M.Sau3AI. Efforts to clone one or both genes in Escherichia coli have so far failed.

Amino Acid Sequence↗