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Biomedical subjects

H Ritter

Publications and source records attributed to H Ritter.

At least 37 records · Page 2Linked to original sources
PubMed1996

Disambiguating complex visual information: towards communication of personal views of a scene.

Two experiments on the perception and eye-movement scanning of a set of six overtly ambiguous pictures are reported. In the first experiment it was shown that specific perceptual interpretations of an ambiguous picture usually correlate with parameters of the gaze-position distributions. In the second experiment these distributions were used for an image processing of initial pictures in such a way that in regions which attracted less fixations the brightness of all elements was lowered. The preprocessed pictures were then shown to a group of 150 naïve subjects for an identification. The results of this experiment demonstrated that in four out of six pictures it was possible to influence perception of other persons in the predicted way, ie to shift spontaneous reports of naïve subjects in the direction of interpretations that accompanied gaze-position data used for the preprocessing of initial pictures. Possible reasons for a failure of such a communication of personal views in two cases are also discussed.

Attention↗
PubMed1995

Detection of two hypervariable (ATTTT)n loci in the human genome.

Object of this investigation was the isolation of a single-locus probe from a multi-locus fingerprint. Individual specific multi-locus fingerprints in man were generated by using the oligonucleotide probe (ATTTT)5. An isolated (ATTTT)5-positive DNA fragment was analyzed using polymerase chain reaction (PCR) cycle-sequencing and nonradioactive direct-blotting electrophoresis. A digoxigenated oligonucleotide synthesized according to this sequence was used as a single-locus probe. Two hypervariable loci were detected on Southern blots. Formal genetic investigations for the two loci were performed in order to estimate the allele frequencies. Locus 1 shows an individual-specific banding pattern with an autosomal-codominant inheritance and can be used for forensic investigations. Locus 2 also represents a polymorphic pattern, but the inheritance is not according to the Mendelian rules. Probably we have detected a highly mutagenic locus in the human genome.

Base Sequence↗
PubMed1995

Comparative clinical trial of granisetron and ondansetron in the prophylaxis of cisplatin-induced emesis. The Granisetron Study Group.

PURPOSE: To compare the efficacy and safety of granisetron and ondansetron, serotonin (5-HT3) receptor antagonists shown to be effective in the prevention of chemotherapy-induced emesis. PATIENTS AND METHODS: In a double-blind, randomized, stratified, parallel-group study, the efficacy and safety of granisetron and ondansetron were compared in 987 chemotherapy-naive patients who received cisplatin in doses > or = 60 mg/m2. Granisetron was administered as a single dose of 10 or 40 micrograms/kg before the start of chemotherapy. Ondansetron was administered in doses of 0.15 mg/kg before and 4 and 8 hours after the start of chemotherapy. The three treatment groups were well-matched with respect to demographic characteristics and the dose of cisplatin administered. RESULTS: For all evaluations, single doses of granisetron 10 or 40 micrograms/kg were as effective as three 0.15-mg/kg doses of ondansetron. Total control (no vomiting, no retching, no nausea, and no use of rescue) was attained by 38%, 41%, and 39% of all patients who received granisetron 10 microgram/kg, granisetron 40 micrograms/kg, and ondansetron, respectively. No vomiting or retching and no use of rescue antiemetics were reported in 47%, 48%, and 51% of patients who received granisetron 10 micrograms/kg, granisetron 40 micrograms/kg, and ondansetron, respectively; no nausea and no use of rescue antiemetics were reported in 39%, 42%, and 40% of patients, respectively. CONCLUSION: All three treatment regimens were well-tolerated. The results of this study indicate that a single dose of granisetron 10 or 40 micrograms/kg is as effective as three doses of ondansetron 0.15 mg/kg in the prevention of nausea and vomiting induced by cisplatin chemotherapy.

Adult↗
PubMed1994

Restriction fragment length polymorphism: molecular weight analysis and calculation with a scanner-based computer system.

For an exact and reproducible molecular weight calculation, an essential requirement in all applications of DNA profiling, we present a new system, called RFLP-MAC (restriction fragment length polymorphism-molecular weight analysis and calculation). The system is composed of a sensitive digital gray-scale scanner unit and an Apple Macintosh computer supported by a powerful combination of a shareware and self-developed software package. Molecular weights are calculated by profiling the optical density and band particle processing parameters to identify the unknown DNA fragments. Mathematical models were used to interpolate the transverse and horizontal migration directions of the molecular weight standards, insuring consistent results from gel to gel. All data are stored in a relational multi-user database system. Descriptive statistics are performed and allele frequencies are analyzed. Procedures for image-analysis, molecular weight calculation, statistical evaluations and database management were developed and run within the multitasking environment of 4th Dimension. Two sets of data, intragel and intergel measurements, are investigated in order to check the precision of the RFLP-MAC system. All these data are subjected to a standard analysis of variance resulting in a maximal 3 SD value of 0.005 (0.288%) for the intragel and of 0.091 (1.654%) for the intergel variation.

Computer Systems↗
PubMed1994

TGGE and HIEF: a comparison of two methods in the detection of carriers of the Z mutation in the alpha-1-antitrypsin gene.

Alpha-1-antitrypsin (alpha-1-AT) deficiency can lead to juvenile liver cirrhosis and lung emphysema in adulthood. The deficiency Z allele is caused by a base transition. Temperature gradient gel electrophoresis (TGGE) and hybrid isoelectric focusing (HIEF) were used to detect carriers of the Z mutation of the alpha-1-AT gene. The resulting data were compared. To verify carriers at the sequence level, a manual nonradioactive sequencing strategy was established. Among our sample of carriers of the Z mutation, two were not detected by HIEF that could be identified by TGGE. DNA of all TGGE identified individuals harboring the Z mutation of the alpha-1-AT gene were sequenced nonradioactively. All carriers harbored a G to A transition at position 11.940. This mutation is described to cause the altered protein.

Alleles↗
PubMed1993

Subtyping of alkylated human orosomucoid: evidence for a duplicated gene, ORM1*F2S.

Isoelectric focusing of human orosomucoid (ORM) was studied following different sample treatment. It is shown that: (i) alkylation with iodoacetamide leads to a drastic change in the isoelectric point (pI) of both ORM1 F2 and ORM2 A gene products and greatly improves the discrimination between ORM1 F1 and ORM1 F2; (ii) previous reduction of the molecule with dithiothreitol partially inhibits the pI transitions with resultant artifactual ORM1 F1F2S patterns that correspond in most cases to F2S phenotypes. With the technique now described, the persistence of three ORM1 gene products was found in only one individual and the segregation analysis is consistent with the existence of a rare ORM1*F2S haplotype.

Alkylation↗
PubMed1993

Polymorphism of glucose dehydrogenase (GDH, EC 1.1.1.47): formal and population genetic data.

The polymorphism of glucose dehydrogenase (GDH) is demonstrated by isoelectric focusing of leucocyte extracts followed by enzyme staining. Segregation in 52 families with 145 children is consistent with the formal hypothesis of three common alleles, GDH*1, GDH*2 and GDH*3, at an autosomal locus GDH. Allele frequencies from 104 unrelated individuals from southwestern Germany were calculated as GDH*1 = 0.70, GDH*2 = 0.18 and GDH*3 = 0.12.

Alleles↗
PubMed1993

Genetic polymorphism of the single locus probes pL159-1 and pL355-8.

The genetic polymorphism of the single-locus probes pL159-1 (D18S17) and pL355-8 (D20S15) was investigated in 445 unrelated individuals using PstI as restriction enzyme. Fragment size calculations were obtained using the molecular weight size marker MW-SBH. The basic relationship between migration distance and molecular weight was transformed using an exponential function. Fragment size frequency data show 2 peaks for pL159-1 at 4.36kb (2.36%) and 4.67 kb (6.29%) and one peak for pL355-8 at 6.04 kb (5.73%). The rate of heterozygosity exceeded 70% for both probes.

Alleles↗
PubMed1993

[Venous aneurysms].

Incidence, etiology, diagnostic procedures and therapy of venous aneurysms, basing on 152 own cases, are discussed. The main procedure for diagnosis is phlebography. It must be distinguished between aneurysms of epi- and subfascial veins. The localization determines the surgical procedure which represents the only successful therapy. Without proper treatment, venous aneurysms may be responsible for complications such as thrombophlebitis, thrombosis with pulmonary embolism, aneurysm rupture and compression of adjacent structures. The results of surgical treatment are excellent.

Aneurysm↗
PubMed1992

Temperature gradient gel electrophoresis: rapid detection of alpha-1-antitrypsin deficiency carriers.

The homozygous state of the alpha-1-antitrypsin (alpha 1AT) deficiency variant Z is associated with severe liver damage in early childhood and progressive lung emphysema in adulthood. A single base transition (G to A in codon 342) in exon V is causing the severe disease. The Glu342 to Lys342 mutation can be detected conventionally by isoelectric focusing (IEF) or on the DNA level by the newly developed method of temperature gradient gel electrophoresis (TGGE). It is the aim of this study to describe the TGGE technique, to compare the results with conventional IEF, and to discuss its efficiency for different diagnostic applications.

Alleles↗
PubMed1992

Genetic studies of antithrombin III with IEF and ASO hybridization.

Antithrombin III (AT III) was analyzed by two different methods. Isoelectric focusing was used to screen 3 different populations (southwest Germans, Portuguese, Xavante Indians). The same variant was detected both in the German and the Portuguese populations with frequencies of 0.007 and 0.00024, respectively. Further characterization of this variant was performed by allele specific oligonucleotides. By this means, it was possible to identify the variant as AT III Dublin, originally found in 4 Irish families.

Antithrombin III↗
PubMed1992

[Waste water pollutants due to the use of disinfectants in the hospital].

It is assumed that the antiseptic effect of disinfectants in effluents from hospitals can severely disturb the growth of microorganisms in the different stages of aeration of sewage plants. Regular biological catabolism could therefore be damaged. The impact of substances on the waste water depends on the concentration of disinfectants they contain. Consequently this essay first examines the expected quantities of antiseptic substances in the effluent of a medium-sized hospital (440 Beds). The effluents treated here however showed a low concentration of disinfectants and it could be proved that these quantities do not have any harmful effects on the examined parameters such as BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand) and pH-value.

Disinfectants↗
PubMed1991

Separation of human alloalbumin variants by isoelectric focusing.

A technique for the separation of human alloalbumin variants by means of isoelectric focusing in the presence of 8M urea and 60 mM L-serine is described. The potential usefulness of this technique in the detection and classification of genetic heterogeneity at the albumin locus is demonstrated by the differentiation of three human alloalbumin variants of European origin.

Europe↗
PubMed1991

Orosomucoid (ORM 1) subtyping and formal genetics.

Orosomucoid (ORM) phenotyping has been performed in 141 families with 407 children from southwest Germany. Eight families were observed in which duplicated ORM1 genes, F1F2, F1F3, segregated. The family data gave no information about the presence of tandemly duplicated ORM1 F1F4 and ORM1 F1F5 genes. To date, the segregation of the phenotypes of the children agrees with the extended formal model: two ORM1 loci with two common (*F1, *S) and several rare (*F1F2, *F1F3, *F4, *F5) alleles. The parental allele frequencies were calculated by gene counting as ORM1 *F1 = 0.5781, *S = 0.3901, *F1F2 = 0.0195, *F4 = 0.0053, *F1F3 = 00.0035, *F5 = 0.0035.

Alleles↗