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C Kessler

Publications and source records attributed to C Kessler.

At least 163 records · Page 9Linked to original sources
PubMed1990

Methodical and ethical aspects of nucleic acid diagnostics. A review.

Aside from the established enzymatic and immunodiagnostic procedures, an increasing number of diagnostic procedures for nucleic acid detection--i.e. for the detection of the primary genetic information--has been developed in recent years. For the routine use of these diagnostic procedures in central analytical laboratories or by the general practitioner, automated DNA analysis methods with integrated highly sensitive detection systems have been developed. The most important objective of these developments--aside from the elucidation of the type of genetic defect on the molecular level through basic research--is the generation of a quantitative nonradioactive signal in corresponding analyzers. Detection methods using the ELISA principle as quantifiable reporter system--analogous to the automatic immunodiagnostic procedures--have hence been developed in recent years. Owing to the increasing importance of this analysis procedure alternative to the detection of bioactive low molecular weight substances or proteins--i.e. nucleic acid diagnostics--the following is an attempt to provide a survey of the methods and possibilities of application. Moreover, possibilities for nonradioactive signal generation and amplification will be presented. The chances and risks of genome diagnostics will be discussed in a final section.

Animals↗
PubMed1989

Cloning, characterization and heterologous expression of the SmaI restriction-modification system.

The genes coding for the class-II Serratia marcescens restriction-modification system have been cloned and expressed in E. coli. Recombinant clones, restricted incoming phage only poorly; the recombinant plasmids, however, became fully modified in vivo, i.e. completely resistant against digestion with R.SmaI. The determined nucleotide sequence of the cloned system revealed three open reading frames with lengths of 252 bp, 741 bp, and 876 bp. Through various deletion experiments and an insertion-mutation experiment the 876 bp open reading frame could be assigned to the SmaI DNA modification enzyme and the 741 bp open reading frame to the SmaI restriction endonuclease. Mapping of the transcription start sites of the genes revealed that the SmaI endonuclease is transcribed as polycistronic mRNA together with a 252 bp long preceding open reading frame of unknown function. No homology was found when comparing the amino acid sequence of M.SmaI with the published sequences of m5C-specific DNA modification methyltransferases. On the other hand, a stretch of 14 amino acids in the C-proximal region of M.SmaI shows a significant homology to the C-proximal amino acid sequences of the N6A-methyltransferases M.HinfI and M.DpnIIA and the N4C-methyltransferase M.PvuII.

Amino Acid Sequence↗
PubMed1989

Dominantly transmitted hematologic dysfunction clinically similar to Fanconi's anemia.

We report a family with a dominantly transmitted syndrome resembling Fanconi's anemia and spanning two generations. This syndrome was characterized by an ill-defined hematologic stem cell disorder, immune dysfunction, poor dentition, hyperpigmented skin, warts, and multiple second trimester spontaneous abortions and included one case of acute myelomonocytic leukemia (acute non-lymphocytic leukemia, M4). This family lacks the characteristic chromosomal aberrations of Fanconi's anemia. We believe this constellation of findings represents an entity not previously described.

Abortion, Habitual↗
PubMed1989

Evoked potential variation in schizophrenic subgroups.

Unmedicated chronic schizophrenic inpatients and nonpsychotic controls were tested in a paradigm designed to elicit habituated event-related potentials (ERPs) to auditory stimuli. Analysis of Variance of the ERP components recorded at bilateral frontal (F1 and F2) and temporal (T3 and T4) scalp leads revealed significant decreases in N1 component amplitudes in both frontal leads in the schizophrenic subjects. P2 and N2 amplitudes also tended to be smaller at frontal leads in the schizophrenic subjects, but these differences were not found to be statistically significant overall. The schizophrenic subjects were assigned to diagnostic subgroups following administration of the Diagnostic Interview Schedule, the Maine Paranoid Scale, and the Scale for the Assessment of Negative Symptoms. Subjects meeting DSM-III criteria for paranoid schizophrenia were assigned to one subgroup (PS subgroup), and those meeting DSM-III criteria for residual or undifferentiated schizophrenia were assigned to another subgroup (RS subgroup). The Analysis of Variance of the N1 amplitude measures was repeated with subgroup diagnosis as a factor, revealing significant decreases in N1 amplitude in the PS, but not the RS, patients. Patients in the PS subgroup were found to differ significantly from those in the RS subgroup on this ERP measure, as well as from controls. These results suggest that subgroup differences exist within the schizophrenic population that are reflected in differential changes in ERP morphology.

Adult↗
PubMed1988

AsnI: a novel class II restriction endonuclease from Arthrobacter sp., strain N-CM, recognizing 5'-AT/TAAT-3'.

A new class II restriction endonuclease, AsnI, with a novel sequence specificity was isolated from the Gram-positive eubacterium Arthrobacter species, strain N-CM. AsnI recognizes the unambiguously defined palindromic hexanucleotide (Formula: see text) consisting of A- and T-residues. The novel enzyme in the presence of Mg2+ cleaves specifically both strands as indicated by the arrows. The staggered cuts generate 5'-protruding ends with single-stranded 5'-TA-3' dinucleotide extensions. The novel enzyme may be a useful tool for cloning experiments by complementation of the few enzymes such as PstI and PvuI cutting only once in the Ampr-gene of plasmids pBR322 and pBR328.

Arthrobacter↗
PubMed1988

Ksp632I, a novel class-IIS restriction endonuclease from Kluyvera sp. strain 632 with the asymmetric hexanucleotide recognition sequence: 5'-CTCTTC(N)1-3' 3'-GAGAAG(N)4-5'.

A new class-IIS restriction endonuclease, Ksp632I, with novel sequence specificity has been discovered in a non-pathogenic species of Kluyvera. The presence of only a single site-specific activity in this Kluyvera sp. strain 632 enables Ksp632I to be isolated in highly purified form free of contaminating nucleases. Ksp632I recognition sites and cleavage positions were deduced using experimental and computer-assisted mapping and sequencing. The cleavage specificity corresponds to the sequence 5'-CTCTTCN decreases NNN-N-3' 3'-GAGAAGN-NNN increases N-5'. The enzyme recognizes an asymmetric hexanucleotide sequence and cleaves in the presence of Mg2+ ions specific phosphodiester bonds in both DNA strands, 1 and 4 nucleotides distal to the recognition sequence. The staggered cuts generate 5'-protruding ends with single-stranded 5'-phosphorylated trinucleotides. Several slow cleavage sites for Ksp632I were observed on lambda cI857Sam7 DNA. Ksp632I may complement other class-IIS enzymes in the universal restriction approach and may serve as a tool for generating defined unidirectional deletions or insertions.

Bacteriophages↗
PubMed1988

Identification and quantification of ethylene glycol and diethylene glycol in plasma using gas chromatography-mass spectrometry.

A method for the gas chromatographic-mass spectrometric identification and quantification of ethylene glycol and diethylene glycol in plasma is described. Such a method is necessary in clinical and forensic toxicology to diagnose probable intoxication and to control the efficacy of detoxification. For sample preparation, the glycols were isolated using acetone after the addition of 1,3-propylene glycol as internal standard. The glycols were then esterified by pivalic acid (pivalic acid anhydride, triethylamine and methanol, 70 degrees C, 15 min) to improve their gas chromatographic characteristics. The glycols were first identified by a comparison of the full mass spectra with reference spectra and then quantified. Therefore, the peak area ratio in the total ion chromatogram (ethylene glycol or diethylene glycol/1,3-propanediol) of the sample was compared with the calibration curve in which the peak area ratios of the standards (0.05, 0.1, 0.5, 1 and 2 g/l), prepared in the same way, were plotted versus their concentrations. The method was linear at least from 0.05 to 2 g/l, with a detection limit of less than 0.01 g/l. The analytical recoveries were 99.2-102.9% for the different concentrations. Precision studies show coefficients of variation of 3.0-6.3% for the different concentrations.

Ethylene Glycols↗
PubMed1988

A comparison of laparoscopy and laparotomy for the treatment of ectopic pregnancy.

A case-control method was used to examine differences in outcome between laparoscopy and laparotomy for the treatment of ectopic pregnancy. Cases and controls, 25 each, were matched by criteria selected to minimize differences in preoperative morbidity and technical difficulty. Patients treated laparoscopically had significantly shorter hospital stays (1.34 +/- 0.8 versus 3.92 +/- 1.1 days; mean +/- SD; P less than .01) and less operating time (77.5 +/- 26.1 versus 103.6 +/- 26.7 minutes; P less than .05). In addition, a laparoscopic approach resulted in a shorter convalescence (8.7 +/- 7.8 versus 25.7 +/- 16.2 days; P less than .01) and reduced postoperative analgesia requirements (0.84 +/- 2.3 versus 4.64 +/- 2.9 doses; P less than .01). We conclude that laparoscopic treatment of ectopic pregnancy is well tolerated by patients and, in comparison with laparotomy, requires fewer medical resources, thereby significantly reducing cost.

Convalescence↗
PubMed1988

[Myotonia congenita with familial spastic paraparesis].

An association of myotonia congenita and hereditary spastic paraplegia has not been reported up to now. We present three cases in one family, who suffer from this combination of syndromes. There are no hints for a pathophysiological connection between these diseases of different systems. A combination of autosomal dominant myotonia congenita and autosomal recessive spastic paraplegia is supposed. Under this hypothesis the risk for an association of the syndromes in the last generation of the reported family with two affected patients is 1/36. A coincidence of these two hereditary diseases seems to be possible.

Adult↗
PubMed1987

Successful pregnancy after pharmacologic suppression of a circulating anticoagulant in a woman with previous pregnancy losses and pulmonary emboli. A case report.

A woman had two second-trimester fetal deaths two weeks after genetic amniocenteses, and her puerperal courses were also complicated by pulmonary emboli. During her next pregnancy a circulating anticoagulant was demonstrated that had been absent between her pregnancies. It was suppressed with aspirin and prednisone. Amniocentesis was uneventful. Despite the development of steroid-induced diabetes, the pregnancy outcome was successful, with no postpartum complications.

Adult↗
PubMed1986

Specificity of restriction endonucleases and methylases--a review.

The properties and sources of all known restriction endonucleases and methylases are listed. The enzymes are cross-indexed (Table I), classified according to their recognition sequence homologies (Table II), and characterized within Table II by the cleavage and methylation positions, the number of recognition sites on the double-stranded DNA of the bacteriophages lambda, phi X174 and M13mp7, the viruses Ad2 and SV40, the plasmids pBR322 and pBR328, and the microorganisms from which they originate. Other tabulated properties of the restriction endonucleases include relaxed specificities (integrated into Table II), the structure of the generated fragment ends (Table III), and the sensitivity to different kinds of DNA methylation (Table V). In Table IV the conversion of two- and four-base 5'-protruding ends into new recognition sequences is compiled which is obtained by the fill-in reaction with Klenow fragment of the Escherichia coli DNA polymerase I or additional nuclease S1 treatment followed by ligation of the modified fragment termini [P3]. Interconversion of restriction sites generates novel cloning sites without the need of linkers. This should improve the flexibility of genetic engineering experiments. Table VI classifies the restriction methylases according to the nature of the methylated base(s) within their recognition sequences. This table also comprises restriction endonucleases which are known to be inhibited or activated by the modified nucleotides. The detailed sequences of those overlapping restriction sites are also included which become resistant to cleavage after the sequential action of corresponding restriction methylases and endonucleases [N11, M21]. By this approach large DNA fragments can be generated which is helpful in the construction of genomic libraries. The data given in both Tables IV and VI allow the design of novel sequence specificities. These procedures complement the creation of universal cleavage specificities applying class IIS enzymes and bivalent DNA adapter molecules [P17, S82].

Base Sequence↗