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Biomedical subjects

D Richter

Publications and source records attributed to D Richter.

At least 271 records · Page 15Linked to original sources
PubMed1990

Nocturnal detachment of the tick Ixodes hexagonus from nocturnally active hosts.

To determine whether the pattern of engorgement of Ixodes hexagonus Leach (Acarina: Ixodidae) in Central Europe may influence host specificity, the host relationships of the sub-adult stages of this tick were examined and the time of detachment compared with the activity patterns of various candidate vertebrate hosts. The main hosts for I. hexagonus appear to be hedgehog and fox. This tick species seems to be incapable of feeding on any rodent commonly encountered in the study region, or on reptiles or birds. Virtually all of these ticks detach during the scotophase, becoming replete mainly during the late evening and early morning hours, regardless of the kind of host or of the time of attachment. These nocturnally detaching ticks, paradoxically, focus their feeding on nocturnally active hedgehogs and foxes, in spite of the possibility that such behaviour might cause them to disperse from the nests of the host. Dispersion is prevented, however, by the tendency of these ticks to detach while their host naps. The tick-host association of I. hexagonus with hedgehogs may serve to perpetuate such zoonotic, Ixodes-borne infections as Lyme disease.

Animals↗
PubMed1990

Poly(A) tail length of oxytocin- and lysine vasopressin-encoding mRNAs increases during development in the porcine hypothalamus.

Lysine vasopressin- and oxytocin-encoding mRNAs have been analysed in the developing hypothalamus of the pig. The two hormone-encoding mRNAs were first detectable on fetal day 49 by Northern blot analysis. Whereas RNase mapping revealed identical transcripts throughout the developmental stages studied, Northern blots showed that the early transcripts appeared to be shorter (by 100-200 nucleotides) and more heterogeneous in size than those of later stages. This developmentally related length polymorphism was shown to be due to different poly(A) lengths and was abolished by removal of the poly(A) tails with RNase H. These results indicate that maturation of neurones in the developing porcine hypothalamus is accompanied by an increase in length of the poly(A) tail of vasopressin and oxytocin mRNAs.

Amino Acid Sequence↗
PubMed1990

[The significance of psychosocial factors for the course of breast cancer--results of a prospective follow-up study].

The meaning of psychosocial factors for the course of breast cancer--First results of a prospective research project. Studies investigating the meaning of psychosocial factors for the course of cancerous diseases have so far been contradictious. In this paper the basic datas and first results of a prospective research project on this topic covering 107 breast cancer patients are reported. Somatic datas such as stage of lymph-nodes, type of surgery and additional treatments (radiation therapy or chemotherapy), are less important for the coping process 6 months after primary treatment than the cognitive attitudes of the patients toward their disease. About 56 percent of the patients coped quite well with their disease, 44 percent showed difficulties. The group of patients whose somatic and psychosocial prognosis was judged rather unfavorably at the time of the first examination, showed the highest rate of recidivation and progredience in the follow-up of the first 12 months.

Adaptation, Psychological↗
PubMed1989

Impact of altered protein structures on the intracellular traffic of a mutated vasopressin precursor from Brattleboro rats.

The rat vasopressin precursor, synthesized in the reticulocyte lysate system under the direction of in vitro transcribed mRNA, is processed and correctly delivered to the lumen of added microsomal vesicles. Translation of mRNA for the mutant (Brattleboro) vasopressin precursor which lacks a translational stop codon as a consequence of a frame-shift mutation, gives rise to a mutated protein (B-mutant precursor) with a C-terminal poly(lysine) sequence encoded by the poly(A) tail. Upon addition of microsomal membranes, the mutated precursor has access to the lumen of the vesicles as indicated by removal of the signal peptide; however, the C-terminal part with the poly(lysine) tail remains outside the vesicles as shown by its sensitivity to proteinase K. When a modified RNA, including a stop codon located similarly to that found in the cDNA encoding the normal precursor, is translated in the presence of microsomal membranes, the resulting product (S-mutant precursor) is refractory to proteolysis by exogenously added proteinase K. Analysis of the microsomal membranes indicates, however, that the C-terminus of the S-mutant precursor is still anchored within membranes. For studying the intracellular transport of the mutated precursor Xenopus laevis oocytes were injected with various RNA constructs. To monitor the transport steps from the endoplasmic reticulum to the Golgi compartment an RNA encoding a glycosylation site within the S-mutant precursor sequence was constructed. The resulting GS-mutant precursor is synthesized in the oocyte but not secreted into the incubation medium, completely in contrast to the normal vasopressin precursor which can be detected in the incubation bath 4 h after injection of the respective RNA. The sensitivity of the GS-mutant precursor carbohydrate side chain to endoglycosidase H treatment suggests that the mutated precursor does not reach the Golgi apparatus.

Acetylglucosaminidase↗
PubMed1989

Differential polyadenylation of the mutant vasopressin mRNA during development of Brattleboro rats.

In the normal (Wistar) rat vasopressin encoding mRNA first appears at embryonic day 15 as demonstrated by in situ hybridization of hypothalamic sections. In mutant (Brattleboro) rats, which possess a defective vasopressin gene with a single nucleotide deletion, the corresponding transcript is not detectable before fetal day 18. In both rat strains however expression of the structurally related oxytocin gene begins at fetal day 19. Whereas normal and mutant vasopressin encoding mRNAs are identical in size up to at least three weeks after birth, the corresponding transcripts from adult Brattleboro but not from normal rats are markedly larger. This increase in size is due to a longer stretch of poly(A) sequence as demonstrated by treatment of the respective mRNAs with RNase H and oligo(dT). Thus the mutant vasopressin gene transcript is subject to a cellular-specific differential polyadenylation process during development.

Age Factors↗
PubMed1989

Two isotocin genes are present in the white sucker Catostomus commersoni both lacking introns in their protein coding regions.

Two genes each encoding a distinct precursor protein to the hormone isotocin and a neurophysin-related protein are present in the teleost fish Catostomus commersoni. These precursors are referred to as isotocin 1 and 2. As shown by the polymerase chain reaction technique, both genes lack introns in their protein-coding sequences. Both genes are transcribed giving rise to mRNAs of 920 (isotocin 1) and 1020 (isotocin 2) bases, respectively. Based on the nucleotide sequences, the predicted isotocin precursors contain, besides the hormone moiety, a neurophysin-like protein that, in contrast to its mammalian counterpart, is extended at its C-terminus by a peptide which includes a leucine-rich core segment. This segment shows similarities to the copeptin of the mammalian vasopressin precursor that is known to possess prolactin-releasing activity. The data imply that the mammalian copeptin sequence was initially part of a larger ancestral neurophysin molecule.

Amino Acid Sequence↗
PubMed1989

[Psychosomatically oriented management of pregnant patients and patients in labor].

Knowledge of psychosocial risk factors and psychosomatic problems of pregnancy, childbirth, and childbed is still rather poor among obstetricians, midwives, pediatric nurses, and pediatricians. This means that psychosocial risk factors and psychosomatic disturbances during pregnancy, childbirth, and childbed are not always and not thoroughly enough discovered and thus they are not treated properly. The necessity of a psychosomatically oriented care of the pregnant woman is pointed out with discussion of basic and advanced psychosomatic treatment.

Adaptation, Psychological↗
PubMed1989

Vasotocin and isotocin precursors from the white sucker, Catostomus commersoni: cloning and sequence analysis of the cDNAs.

The nucleotide sequences of cloned cDNAs encoding the precursors for vasotocin and isotocin have been elucidated by analyzing a lambda gt11 library constructed from poly(A)+ RNA from the hypothalamic region of the teleost fish Catostomus commersoni. Screening of the library was carried out with synthetic oligonucleotide probes deduced from the amino acid sequences of the nonapeptides vasotocin and isotocin. The cDNA nucleotide sequences predict isotocin and vasotocin prohormone precursors each consisting of a signal peptide, a hormone moiety, and a neurophysin-like molecule. However, in comparison to their mammalian counterparts, both fish neurophysins are extended at their C termini by an approximately 30 amino acid sequence with a leucine-rich core segment. These extensions show striking similarities with the glycopeptide moiety (the so-called copeptin) present in mammalian vasopressin precursors, except that they lack the consensus sequence for N-glycosylation. These data suggest that mammalian copeptin is derived from the C terminus of an ancestral neurophysin.

Amino Acid Sequence↗
PubMed1989

[Applicability of the subrenal capsule assay (SRCA) in primary breast carcinoma].

We have examined the application of the subrenal capsule assay (SRCA) by use of normal immunocompetent (NIC) mice for chemosensitivity testing of primary breast cancers. In 18 out of 20 carcinomas an evaluation was possible. AB mice (10 breast cancers) and B6D2-F1 mice (10 breast cancers) were taken as recipients. Measurement of the size and the histological examination of all transplants were obligatory performed before and after finishing the assay on day 6. By use of AB mice as well as B6D2 mice in each group in 6 out of 9 evaluable cancers occurred a significant growth of the transplanted tissues after 6 days (p less than 0.05). It could be demonstrated by the histological examination that the enlargement was a consequence of the immunological reaction of the NIC mouse to the xenogeneic material. In most cases (76 of 97 used mice) the transplants consisted of inflammation cells only. Vital tumor cells were seen only in few cases (21 of 97 used mice). It is concluded, that the SRCA is not suitable for chemosensitivity testing of human breast cancer, if NIC mice as recipients are used.

Animals↗
PubMed1989

[Use and efficacy of extracorporeal detoxication procedures in poisoning in children].

We could demonstrate the possibilities and limitations of the extracorporal detoxications by accidental poisonings in children. The effective use of hemodialysis, hemoperfusion, and plasmapheresis in poisonings during childhood under special consideration of the parameters such as molecular weights, half time rate, proteinbinding, distribution volume, pattern of solubility, and metabolism is shown and critically discussed.

Child↗
PubMed1989

[Causal attributions and coping with illness in patients with breast cancer].

The aim of the present study was to investigate whether breast cancer patients who attribute their disease to different causes differ in their ability to cope with the disease. A semistructured interview technique was used to question a total of 107 patients, six months after the operation, about the psychological stress involved in their disease and how they coped with it. In addition, two further questionnaires were used: the Freiburg questionnaire concerning adjustment to the disease (FKV) and another questionnaire to register the causes to which the patients attributed their disease (PUK). The results revealed that environmental pollution was the most frequent and important cause of disease mentioned by the patients. This mainly correlated with depressive adjustment to the disease. The same type of adjustment was also frequently seen in patients who attributed their disease to individual psychic problems. Daily stress mentioned as the cause of disease was additionally closely connected with the desire for social support. In accordance with the poor adjustment in connection with internal causes reported in the literature, it was further shown that attribution to psychic causes made psychic adjustment to the disease more difficult, at least within the first six months after the operation.

Adaptation, Psychological↗
PubMed1989

[Evaluation of the subrenal capsule assay (SRCA) in breast cancer using immunocompetent (NIC) mice].

UNLABELLED: To assess the value of subrenal capsule assay (SRCA) for predictive chemo-sensitivity testing in breast cancer 24 primary tumours were examined in normal immunocompetent (NIC; AB- and B6D2-F1-) mice. In 6 cancers the effect of 0.25 mg Prednisolone mous X day (applicated with drinking water) was compared to the control group. Independent of the mice-species a significant increase of the grafts size occurred in 14 of 20 evaluable cancers (p less than 0.05). Histologically the increase of tumour size was caused by infiltrated host cells, only in 22 of 107 (20.6%) grafts vitale tumour cells were detectable. After immunosuppression the increase of the grafts size was significant lower, than in the no treated control group (p less than 0.05). In groups treated with Prednisolone only a thin inflammatory host cell infiltration was observed, but vital tumour cells were only seen in 3 of 29 (10.3%) grafts. CONCLUSION: Using normal immunocompetent mice subrenal capsule assay is not suited for predicting responsiveness of breast cancers to cytostatic drugs.

Animals↗