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C Kessler

Publications and source records attributed to C Kessler.

At least 91 records · Page 5Linked to original sources
PubMed1996

Cloning and characterization of the MamI restriction-modification system from Microbacterium ammoniaphilum in Escherichia coli.

The genes encoding a class-IIN restriction-modification (R-M) system (MamI, sequence specificity [symbol: see text] from Microbacterium ammoniaphilum have been cloned in Escherichia coli. The vector used for cloning was plasmid pUC18 modified by the inclusion of three MamI recognition sites. Recombinant clones containing the mamIM gene in its genomic context became fully methylated in vivo and remained completely resistant against digestion with the R.MamI restriction endonuclease (ENase). Determination of the nucleotide (nt) sequence revealed three open reading frames with lengths of 1089 bp (ORF1), 276 bp (ORFc) and 927 bp (ORF2). On the basis of expression and deletion experiments, the 1089-bp ORF1 was assigned to mamIM encoding the M.MamI DNA methyltransferase (MTase). By amino acid sequencing of the N terminus of R.MamI and comparison of the deduced nt sequence with ORF2, the 927-bp ORF2 was identified as the mamIR gene encoding R.MamI. The 276-bp ORFc, located between mamIR and mamIM, is part of the DNA sequence downstream from mamIM shown to be necessary for controlled mamIM expression.

Amino Acid Sequence↗
PubMed1996

Novel specific endonuclease activity recognizing a 10-bp sequence.

We report here the generation of a novel restriction endonuclease (ENase) activity with the 10-bp recognition sequence, [symbol: see text]. This specificity could be achieved by first methylating a substrate DNA with M.MamI in vivo, followed by in vitro R.DpnI restriction.

Base Composition↗
PubMed1996

[Prognostic factors and clinical outcome in symptomatic focal epilepsies].

Successful drug therapy for symptomatic focal epilepsy is often difficult to achieve. The aim of our study was to determine predictors of seizure-free versus therapy-resistant courses of epilepsy. To accomplish this, we evaluated clinical data obtained early in the course of focal symptomatic epilepsy to determine which factors best determine the probability of therapeutic success. This retrospective study included 70 patients who were treated at the Neurology Clinic, University of Greifswald, between 1984 and 1992. Inclusion criteria were: Clear clinical diagnosis, a minimum of 3 years follow up in our epilepsy outpatient clinic, therapy with standard anticonvulsant drugs, and good compliance. We distinguished between patients who were seizure-free for at least two years and those who were not. 22 patients (31.4%) were seizure-free, whereas 48 patients (68.6%) remained resistant to pharmacotherapy. Prognostic factors for seizure-free outcome were: Focal grand mal seizures as the only seizure type ever experienced by the patient, the occurrence of only one type of seizures during the course of the illness, the occurrence of only nocturnal seizures, few grand mal seizures before starting an effective anticonvulsant therapy, no previous status epilepticus, and the remission of focal epileptic EEG patterns during effective drug therapy.

Adolescent↗
PubMed1996

Basilar artery blood flow during head rotation in vertebrobasilar ischemia.

PATIENTS AND METHODS: Forty-six patients with vertebrobasilar ischemia and 40 control subjects were examined during head rotation using transcranial Doppler ultrasonography. RESULTS: In the control group, no difference in blood flow velocity through the BA was found between the neutral and rotated positions. Based on these data, a blood flow reduction in the BA of more than 20% was considered to be significantly abnormal (p < 0.01). In three of 46 patients no signal was detectable in the BA using TCD. The reduction in blood flow velocity through the BA during head rotation was strongly dependent on the condition of the VA; none of 23 patients without atherosclerotic lesions or hypoplasia of the VA developed a significant reduction in blood flow through the BA. Two of 11 patients with unilateral VA lesions had significantly reduced blood flow in the BA (27% and 31%), although both were asymptomatic. Five of nine patients with bilateral VA lesions showed a significant reduction in blood flow through the BA (mean = 52%, minimum = 30%), and four of these developed clinical symptoms such as vertigo or diplopia during the rotation maneuver. CONCLUSION: These data suggest that patients with uni- or bilateral lesions of the VA are at risk for developing clinically relevant reductions in blood flow through the BA during head rotation. Because not all patients with VA lesions developed reduced blood flow velocity, we conclude that individual vascular mechanisms must play an important compensatory role.

Adult↗
PubMed1996

Power Doppler ultrasound examination of the intracerebral and extracerebral vasculature.

Power Doppler is a new ultrasound technique based on the visualization of the Doppler power spectrum. In 22 patients with different lesions of brain-supplying vessels the results of power Doppler ultrasound were compared with those of digital subtraction angiography and conventional color Doppler ultrasound. In patients with intracranial high-degree stenoses, power Doppler was largely free of those artifacts that occur with conventional color Doppler (e.g., echoshadowing and aliasing). The vessel lumen was seen in all patients with more than 80% stenoses. Power Doppler was superior to conventional color Doppler in visualizing both middle cerebral artery stenosis and intracerebral aneurysms. Power Doppler visualization of intracranial pathology was similar to visualization by digital subtraction angiography. Power Doppler appears to be a valuable tool in the noninvasive imaging of intracranial and extracranial pathological vascular conditions.

Angiography, Digital Subtraction↗
PubMed1996

Cerebrovascular disease assessed by color-flow and power Doppler ultrasonography. Comparison with digital subtraction angiography in internal carotid artery stenosis.

BACKGROUND AND PURPOSE: An understanding of carotid atherosclerosis is important to further our knowledge regarding the etiology of cerebral ischemia, and therefore it is necessary to accurately visualize carotid stenosis. The purpose of the present study was to compare different imaging techniques to determine their advantages and disadvantages in the diagnosis and quantification of middle- and high-grade internal carotid artery stenosis. In particular, we were interested in evaluating the effectiveness of the new ultrasound technique power Doppler. METHODS: Fifty-four patients with greater than 50% extracranial internal carotid artery stenosis, as determined by continuous-wave Doppler, were recruited prospectively to serve as subjects. All subjects were examined with color-flow Doppler, power Doppler, and digital subtraction angiography to enable visualization of carotid stenosis and plaque surface morphology. RESULTS: Thirty-four middle-grade stenoses (50% to 69%), 32 high-grade stenoses (70% to 99%), and 7 complete occlusions of the internal carotid artery were diagnosed with the use of digital subtraction angiography. Power Doppler visualized stenosis significantly more frequently and accurately than color-flow Doppler. Color-flow Doppler tended to overestimate and underestimate in patients with both middle- and high-grade stenosis. Power Doppler was superior to both color-flow Doppler and angiography with regard to differentiation of plaque surface morphology. CONCLUSIONS: This study demonstrates that power Doppler is an important, noninvasive imaging technique that has several advantages over color-flow Doppler in diagnosing carotid artery stenosis and visualizing plaque surface. Power Doppler, used in concert with other ultrasound techniques, should enable a more accurate detection and treatment of cerebrovascular disease.

Aged↗
PubMed1996

Power Doppler--a new tool for transcranial duplex assessment of intracranial vasculature.

The present study was undertaken to assess the clinical use of power Doppler (PD) as a new tool for transcranial vessel imaging. Power Doppler displays the integrated power of the Doppler signal instead of the Doppler frequency shift used in the conventional color flow Doppler (CFD) technique. Twenty-one patients were evaluated who had intracranial malformations or arterial stenoses [4 middle cerebral artery (MCA) stenoses, 2 intracranial carotid stenoses, 7 arteriovenous malformations (AVM), 5 intracranial carotid aneurysms, 3 Moya-Moya syndromes]. The PD results were compared with those obtained from CFD and digital subtraction angiography (DSA). Power Doppler was able to visualize 3 of 4 MCA stenoses with greater morphological detail than CFD, whereas PD and CFD were equally effective in diagnosing carotid stenoses. All AVMs were visualized using PD as well as CFD, but again PD revealed more morphological details, in a manner similar to DSA. Power Doppler was also superior to CFD in imaging intracerebral aneurysms and pathological collateralization associated with Moya-Moya syndromes. It is evident from these data that PD permits reliable and detailed transcranial imaging and therefore is a superior method for visualizing intracerebral vascular malformations and arterial stenoses.

Blood Flow Velocity↗
PubMed1996

[Hysteria, dissociation and conversion. A review of concepts, classification and diagnostic instruments].

Modern theories on hysteria are presented by describing the historical context of various scientific approach to hysterical phenomena as well as the concepts of dissociation and conversion which are closely linked. The subdivision of the classical hysterical neurosis into the dissociative disorders and the somatoform disorders within the diagnostic classifications of ICD-10 and DSM-III-R respectively DSM-IV is illustrated and discussed. These new theories have prompted the development of some instruments such as diagnostic interviews (SCID-D) and self-measuring questionnaires (DES). The scientific value and importance of these instruments is discussed, especially with regard to further studies on dissociative disorders, particularly in the German-speaking countries.

Conversion Disorder↗
PubMed1995

Ultrasound for the assessment of the embolic risk of carotid plaques.

In a prospective study we compared duplex-ultrasound characteristics of symptomatic internal carotid artery (ICA) stenoses with cranial computerized tomographic (CCT) findings in 82 patients suffering from completed or transient middle cerebral artery symptoms. The aim was to assess the pathogenic role of ICA plaque morphology and the potential embolic risk of ICA plaques. The degree of carotid stenosis was estimated by spectral analysis of the pulsed Doppler signal. The CCT findings were classified as being either normal, lacunar lesions, hemodynamically induced low-perfusion infarctions, or territorial embolic infarctions. According to their ultrasonic features we characterized the ICA plaque surface as smooth or irregular and their structure as homogeneous or heterogeneous. Plaques with an irregular surface and heterogeneous echogenicity dominated significantly in CCT-territorial infarctions (p < 0.01), whereas hemodynamically induced low-perfusion infarctions showed no relationship with any plaque characteristic. High degree ICA stenoses (> 50%) dominated in both territorial infarctions and low-perfusion infarctions, as compared to ipsilateral normal CCT or lacunes (p < 0.05). Normal CCT and lacunar infarctions were associated with homogeneous and smooth plaques (both p < 0.05). We conclude that > 50% ICA stenoses can cause both hemodynamically induced low-perfusion infarctions as well as thromboembolic territorial infarctions, whereas ulcerated and heterogeneous plaques constitute a high risk factor for arterio-arterial embolic stroke. Furthermore, carotid ultrasound may help to estimate the clinical significance of carotid lesions.

Adult↗
PubMed1995

[Determinants of arterial embolism with special reference to atheromatous changes of the thoracic aorta].

Potential sources of arterial embolism were evaluated with special emphasis on aortic atheromatosis in patients who underwent transesophageal echocardiography for various clinical reasons. Among 375 patients, 166 had suffered from cerebrovascular disease or peripheral embolism and 209 were free from symptoms of embolism. Univariate analysis revealed that atheromatosis of the aortic arch and descending aorta as well as cardiac thrombi, aneurysms of the interatrial septum and arterial hypertension were significantly more common in patients who had a history of embolism or ischemic stroke. In a stepwise multiple regression analysis, aortic arch atheromatosis (odds ratio 1.7, 95% CI 1.1-2.6), cardiac thrombi (odds ratio 4.1, 95% CI 1.7-9.8), atrial septal aneurysm (odds ratio 3.0, 95% CI 1.2-7.8) and arterial hypertension (odds ratio 1.8, 95% CI 1.1-3.0) were determined as independent predictors of embolic symptoms. We conclude that atheromatous lesions of the aortic arch are an independent risk factor for arterial embolism and ischemic stroke among other well known sources of embolism.

Aged↗
PubMed1994

Non-radioactive analysis of biomolecules.

An overview on non-radioactive bioanalytical indicator systems is presented. The nature of labels being important for direct as well as indirect systems is discussed. This is followed by the description of enzymatic, photochemical and chemical methods for labeling nucleic acids, proteins and glycans. These methods can be applied either for direct labeling of these biomolecules or for labeling of respective probes (DNA, RNA, oligonucleotides, antibodies, lectins). In the second part, various optical, luminescent and fluorescent detection approaches are described. The possibility to enhance the sensitivity by coupled amplification reactions (signal amplification, target-specific signal amplification, target amplification) is shown in a separate section. Finally, the wide variety of qualitative and quantitative reaction formats related to different applications is collected.

Biotechnology↗
PubMed1994

1-Deamino-8-D-arginine vasopressin (DDAVP) increases platelet membrane expression of glycoprotein Ib in patients with disorders of platelet function and after cardiopulmonary bypass.

1-deamino-8-D-Arginine vasopressin (DDAVP) shortens the bleeding time in some patients with platelet dysfunction and decreases blood loss in some cardiopulmonary bypass patients. We studied platelet membrane glycoproteins in patients with von Willebrand disease (vWD), disorders of platelet function, and in cardiopulmonary bypass patients after infusion of 0.3 microgram/kg of DDAVP. Platelets from 8 cardiopulmonary bypass patients, receiving DDAVP immediately after surgery, were compared to those of 14 patients not receiving DDAVP. We also studied 12 patients with vWD, and 8 patients with platelet dysfunction receiving DDAVP. Fixed platelets, stained with monoclonal fluorescein (FITC)-labeled antibodies directed against GPIb (CD42b antigen), GPIb/IX, GPIIb/IIIa (CD41a antigen), CD63 antigen (a platelet activation protein), and P-selectin (CD62 antigen) were studied by flow cytometry. Binding of CD42b monoclonal antibody (MoAb) and anti-GPIb/IX to platelets from both groups of bypass patients increased during the 18-20 hr after surgery, but the group receiving DDAVP showed the greater increase (P = 0.032). Platelets from patients receiving DDAVP for vWD or for platelet dysfunction, had increases in CD42b MoAb and anti-GPIb/IX binding (P < 0.01) that coincided with shortening of their bleeding time. No changes were seen in binding of other antibodies. When platelets from normal donors were incubated with DDAVP for 20 hr, there were increases in platelet surface CD42b MoAb binding, while immunogold-stained transmission electron micrographs of permeabilized platelets demonstrated decreases in cytoplasmic CD42b MoAb binding. DDAVP increases platelet membrane GPIb expression in a variety of patients and may account for improvement in hemostasis seen in some studies. Redistribution of GPIb from the cytoplasm to the membrane may account for this increased expression.

Adult↗
PubMed1994

Nonradioactive labeling and high-sensitive detection of PCR products.

The polymerase chain reaction (PCR) represents the most common and widespread method for the direct amplification of specific sequences of nucleic acid target molecules. Incorporation of nonradioactive labeled nucleotides during PCR by Taq DNA polymerase results in directly detectable amplification products or generates nonradioactively labeled probes for nucleic acid hybridization. Here we provide a reliable and easy to follow protocol for direct incorporation of digoxigenin-(DIG) or biotin-labeled nucleotides during PCR. The combination of high-efficient PCR amplification and high-sensitive digoxigenin technology is leading to the detection of single DNA molecules by applying digoxigenin-specific antibodies in an ELISA-type detection reaction. Following a transfer to nylon membranes, the detection of digoxigenin-labeled amplification products can also be accomplished either with a colorimetric or a chemiluminescent reaction. Using the digoxigenin-labeled amplification products as hybridization probes, sensitivities in the 0.1-pg range are obtained in Southern blot procedures.

Biotechnology↗
PubMed1994

Gender differences in sexual fantasy and behavior in a college population: a ten-year replication.

This report is a replication of a study conducted 10 years ago by Person et al., investigating gender differences in sexual behaviors and fantasies in a college population. We found that men continue to fantasize more than women, but the gender differences have narrowed. Recent sexual experiences of our population show a trend toward an increase in gender differences, and there is a greater correlation between sexual fantasy and experiences in women than in men. As in Person's study, we did not find that men had more aggressive/sadistic fantasies than women.

Adult↗
PubMed1994

Systemic embolism in aortic arch atheromatosis.

The role of aortic atheromatosis as a risk factor for systemic embolism and its relationship to other potential sources of embolism was examined in 335 patients undergoing transoesophageal echocardiography for various clinical reasons. Multiple logistic regression analysis revealed a significant correlation between embolism and moderate (atheroma protruding less than 5 mm into the aortic lumen, grade 2) to complex (atheroma protruding at least 5 mm into the vessel lumen with or without mobile components, grade 3) atherosclerosis of the aortic arch. Odds ratios were 4.0 for grade 2 atheromatosis (95% CI 1.1-14.4; P < 0.05) and 9.7 for grade 3 atheromatosis (95% CI 1.5-61.0; P < 0.05). Other significant associations were found with cardiac thrombi (odds ratio 4.0, 95% CI 1.7-9.3; P < 0.005) and hypertension (odds ratio 1.8, 95% CI 1.0-3.3; P < 0.05). In a subset of 163 patients in whom results of an ultrasound examination were available, atherosclerosis of the carotid arteries was another significant marker of embolism (odds ratio 2.0, 95% CI 1.2-3.3; P < 0.01). In conclusion, aortic arch atheromatosis, which was predominantly recognized in patients with cerebrovascular events of undetermined cause, seems to carry a risk of embolism that is comparable to cardiac and carotid atherosclerosis.

Aorta, Thoracic↗