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Biomedical subjects

F Buchholz

Publications and source records attributed to F Buchholz.

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

Different thermostabilities of FLP and Cre recombinases: implications for applied site-specific recombination.

Genomic manipulations using site-specific recombinases rely on their applied characteristics in living systems. To understand their applied properties so that they can be optimally deployed, we compared the recombinases FLP and Cre in two assays. In both Escherichia coli and in vitro, FLP shows a different temperature optimum than Cre. FLP is more thermolabile, having an optimum near 30 degrees C and little detectable activity above 39 degrees C. Cre is optimally efficient at 37 degrees C and above. Consistent with FLP thermolability, recombination in a mammalian cell line mediated by a ligand- regulated FLP-androgen receptor fusion protein is more efficient at 35 degrees C than at higher temperatures. We also document a mutation in a commercially available FLP plasmid (FLP-F70L) which renders this recombinase even more thermolabile. The different temperature optima of FLP, FLP-F70L and Cre influence their strategies of usage. Our results recommend the use of Cre for applications in mice that require efficient recombination. The thermolabilities of FLP and FLP-F70L can be usefully exploited for gain of function and cell culture applications.

Amino Acid Sequence↗
PubMed1996

A simple assay to determine the functionality of Cre or FLP recombination targets in genomic manipulation constructs.

We report the construction of two Escherichia coli strains (294-Cre and 294-FLP) which express either Cre- or FLP-recombinase. Plasmids containing authentic recognition targets for either recombinase (loxPs or FRTs) are recombined when propagated in the appropriate strain. 294-Cre and 294-FLP thus provide a simple test for the recombination competence of constructs that are designed for use in Cre- or FLP-mediated genomic manipulations.

DNA Nucleotidyltransferases↗
PubMed1996

A novel family of Cys-Cys, His-Cys zinc finger transcription factors expressed in developing nervous system and pituitary gland.

A screen designed to identify proteins that specifically bind to retinoic acid response elements resulted in the identification of a rat cDNA encoding a novel protein containing six Cys-Cys, His-Cys zinc fingers. This gene is expressed in a restricted fashion exhibiting distinct temporal and spatial patterns in the developing nervous system, primarily brain, spinal cord, sensory ganglia, retina, and nasal epithelia, as well as in the pituitary, and is referred to as neural zinc finger factor 1 (NZF-1). NZF-1 binds specifically to a cis-regulatory element of the beta-retinoic acid receptor (RAR beta) gene, as well as to other related DNA elements, including two in the upstream enhancer region of the mouse Pit-1 gene. In heterologous cells, NZF-1 activates transcription from promoters containing specific binding sequences and can synergize with other factors, such as Pit-1, to regulate gene expression. These results suggest that NZF-1 may exert regulatory roles in the developing and mature nervous system and in the pituitary gland. Identification of a second mouse gene highly homologous to NZF-1, encoded by a distinct genomic locus, reveals a dispersed gene family encoding proteins containing Cys-Cys, His-Cys motifs.

Amino Acid Sequence↗
PubMed1992

Brain death: practicability of evoked potentials.

Multimodally evoked potentials were registered in 85 patients who fulfilled the criteria for brain death. While somatosensory and visual evoked potentials have been found to be of limited value for the diagnosis of brain death, the stepwise abolition of brain stem auditory evoked potentials (BAEP) confirmed brain death in 26 out of 85 patients, i.e. 31%. Registration of the abolition of BAEP is concluded to be a safe and acceptable confirmatory test. It is, however, more feasible for institutions, in which BAEP are analysed routinely. In spite of all efforts sequential BAEP could not be used for the diagnosis of brain death in the majority of cases either because of absence of reproducible responses at the initial registration or because the patient was already apnoic at the time of the initial BAEP. Assuming that bilateral preservation of wave I has the same significance as the stepwise abolition of BAEP, since it also proves the integrity of the peripheral receptor, BAEP are relevant for the declaration of brain death in approximately 30% of patients.

Brain Death↗
PubMed1992

Macrophage- and lymphocyte-subtypes in the endometrium during different phases of the ovarian cycle.

The presence of immunocompetetive cells in the endometrium during the proliferative and secretory phase of the ovarian cycle is demonstrated on the light and electron microscopic level using monoclonal antibodies (MoAb). Subtypes of monocytes, macrophages and T-lymphocytes appear during the different phases in variable extent and different localization. Some subpopulations of the monocyte/macrophage system and T-helper lymphocytes increase in number on day 21/22. Our observations indicate that cells with bone marrow origin take part in functional events of the endometrium during the ovarian cycle.

Antibodies, Monoclonal↗
PubMed1991

Lymphoreticular cells in invasive carcinoma of the uterine cervix: an immunohistological study.

In the present study the immunohistology of the cellular stromal reaction of invasive squamous cell carcinoma of the cervix is investigated. Tumor tissue from 10 patients with invasive squamous cell carcinoma of the uterine cervix (stages Ib-IIb, according to FIGO) was immunostained by the alkaline phosphatase-anti-alkaline phosphatase (APAAP) method. The monoclonal antibodies OKT3, OKT4, OKT8, TO15, Ki-M1, and Ki-M6 were applied. The cells in the stroma and the tumor foci were evaluated separately. In all cases, the overwhelming majority of lymphoreticular cells were found in the stroma and the tumor-cell complexes contained relatively low numbers of these cells. While B-lymphocytes were present only in low numbers or were virtually absent from the lymphoreticular infiltrates, cells of the mononuclear-phagocyte system were found to be another prominent constituent of the tumor's cellular stromal reaction.

B-Lymphocytes↗
PubMed1989

[Immunophenotyping of lymphoreticular cells in the human decidua].

The endometrial stroma is transformed into decidua by an adequate hormonal stimulus or by pregnancy, the endometrial stroma is transformed into decidua. There is increasing evidence, that the decidua has a central functional relevance for the survival of the mammalian embryo in an immunological competent host. In this study, the decidua of 10 patients were examined after therapeutic abortion in the 8th-10th week of pregnancy. Various monoclonal antibodies were used for immunophenotyping of lymphoreticular cells. Most intradecidual lymphoreticular cells could be identified as Ki-M6+ and Ki-M8+ macrophages, which also expressed HLA-DR (class-II) antigens. This finding is underlined by the fact, that Tü-35+ cells occurred in comparable numbers as macrophages and B-lymphocytes were virtually absent from the decidua. Next in frequency were OKT3-positive T-lymphocytes. Most of the lymphoid cells were detected by monoclonal antibody OKT8 (suppressor/cytotoxic lymphocytes) while OKT4+ helper/inducer cells occurred only in low numbers. Though definite conclusions in the cells' functional properties cannot be drawn from an immunohistological study, our findings might be regarded as a basis to explain the tolerance of the embryo in this apparently privileged immunological site.

Antibodies, Monoclonal↗
PubMed1989

Recombinant human interferon (IFN) alpha-2b in chronic myelogenous leukaemia: dose dependency of response and frequency of neutralizing anti-interferon antibodies.

Twenty-seven patients with Philadelphia chromosome positive chronic myelogenous leukaemia in the chronic phase were treated with low doses of recombinant interferon (IFN) alpha-2b. Ten patients entered a complete and six a partial haematologic remission with a median duration of 5.8 and 9.1 months respectively. Five minor cytogenetic responses were observed. These results are inferior compared to other studies with higher interferon-doses. Fever was an acute side effect after injection of IFN, limb pains and fatigue occurred protractedly. Haematologic side effects, nonspecific EEG changes, weight loss, and development of pulmonary infiltrates were observed in later periods of the treatment. Eight patients developed neutralizing anti-IFN antibodies after 4.2-20.4 months (median 12.8 months). Anti-IFN antibodies were associated with relapse or refractoriness to IFN treatment: five out of nine patients with rising WBC after initial fall had antibodies, while four did not. Two out of four patients with primary non-response had IFN-antibodies. These results may indicate a serious problem in the long-term treatment of CML with recombinant interferon.

Adolescent↗
PubMed1988

Histopathology of tubal pregnancy.

The histopathological examination of several sections of tubal ectopic pregnancies shows that the growth of the trophoblast usually takes place in an extraluminal subperitoneal site and dilation of the tube is caused by coagulated blood and not by the trophoblast. For conservative surgery of the tube it is necessary to keep in mind the histopathological findings of tubal pregnancies.

Female↗
PubMed1988

[Lymphoreticular cells in the human endometrial stroma].

The endometrium of 12 patients with a normal spontaneous uterine cycle was examined immunohistochemically with the indirect PAP-method using various monoclonal antibodies. Lymphoreticular cells, which are responsible for non-specific defense mechanisms and for the cell-mediated immune reactions were identified. In all phases of the normal cycle, high numbers of cells belonging to the mononuclear phagocyte system (MPS) and T-lymphocytes were detected in the endometrial stroma. The overwhelming majority of T-lymphocytes were found to be of the suppressor/cytotoxic cell type, while helper/inducer cells were seen only in comparably low numbers. B-lymphocytes were virtually absent from the endometrial stroma.

Adult↗
PubMed1988

[Possibilities and limits of contact hysteroscopic assessment of the causes of postmenopausal bleeding ].

In this study, the contact-hysteroscopic findings are compared with the histopathological diagnosis of 168 patients who were treated for post-menopausal bleedings. The good diagnostic agreement between contact-hysteroscopy and histopathology in mostly benign alterations like atrophic endometrium (94.7%), polyposis (87.5%), mucosal polyps (88%) and myomas (100%) is not achieved in precancerous (77%) and cancerous (75%) lesions. Being an optical method, contact hysteroscopy necessarily fails in the evaluation of origin, dignity and degree of differentiation of malign lesions, and is no substitute for a histopathological diagnosis. Therefore, contact hysteroscopy may only provide additional information to dilatation and curettage and thus optimize results and diagnostic security.

Adenocarcinoma↗
PubMed1987

Surface morphology of the perfused rabbit ovary.

Using transmission electron microscopy we examined the morphology of the surface epithelium of the isolated and perfused rabbit ovary after an ovulatory dose of HCG. Rupture of follicles occurred in vitro approximately 13 h after HCG-injection and 6 h after the start of perfusion. The ultrastructural changes during the perfusion were similar to those occurring in vivo. The perfused ovarian epithelium had villous processes of varied architectural complexity with squamoid and cuboid epithelial cells. The superficial cells contained pinocytotic vesicles, coated and noncoated endocytotic caveolae, and occasional vacuoles. Dense bodies were more commonly found in vitro than in vivo. Occasionally structures similar to "Call-Exner-bodies" were found on the surface epithelium near to preovulatory follicles. Intercellular spaces of various sizes were also numerous. Disappearance of surface epithelium in the apex of follicles was often observed and the matrix of the tunica albuginea consisted of dissociated fibers and degenerating cells. This study showed that the isolated perfused rabbit ovary can serve as a model for studying the biology and pathology of ovarian surface epithelium.

Animals↗
PubMed1987

[Immuno-oncologic aspects in invasive squamous cell carcinoma of the uterine cervix].

Five patients with an invasive squamous cell carcinoma of the cervix uteri were investigated histologically and immunohistologically to assess localization and composition of the lymphoreticular infiltrates. The relevant cell populations of local immunomechanisms (T-lymphocytes, monocytes/macrophages and plasma cells) were often found numerous in all neoplasms. It must be emphasized that an in situ histomorphological analysis of the cellular part of the stromal reaction of invasive squamous cell carcinoma of the cervix allows only limited conclusions concerning the functional properties of the tumor-infiltrating lymphoreticular cells.

B-Lymphocytes↗
PubMed1986

[Histopathology of tubal pregnancy].

The histopathological examination of several sections of tubal ectopic pregnancies shows that the growth of the trophoblast mostly takes place in an extraluminal site subperitoneally and that the dilated tube is caused by coagulated blood and not by the trophoblast.

Fallopian Tubes↗
PubMed1986

[Ovarian surface epithelium and its histogenic relation to ovarian cancer].

Approximately 80 to 90 per cent of adult ovarian cancers are assumed to originate from ovarian surface cells. A series of morphological and biochemical studies has been recently conducted to test this. The ovarian surface epithelium shows permanent morphological changes such as crypts, inclusion cysts, villous processes and different forms of müllerian epithelium. The unique nature of ovarian surface changes and their abrupt disappearance in immediately adjacent mesothelia suggest that local factors may play an important part in modifying the growth and morphogenesis of the epithelium of the ovarian surface. Whether these endogenous and/or exogenous factors may also induce surface neoplasia is a moot point.

Antigens, Neoplasm↗
PubMed1986

[Extramammary Paget's disease: clinical and histologic documentation of 2 forms].

There are two forms of extramammary Paget's disease in respect of clinic, therapy and prognosis. In most cases (about 95%) extramammary Paget's disease is an intraepidermal manifestation of a cutaneous adenocarcinoma. After horizontal spreading within the epidermis, malignant growth continues along the adjacent adnexal structures with dermal spreading and subsequent metastases. In rare cases (approx. 5%), extramammary Paget's disease is an epidermal manifestation of an adenocarcinoma primarily located in the intestinal or urogenital tract. Further diagnostic and therapeutical procedures depend upon the type of extramammary Paget's disease.

Adenocarcinoma, Mucinous↗
PubMed1985

[Extraoral manifestation of a white sponge nevus of the mucosa].

The nevus spongiosus albus mucosae (resp. white sponge nevus in the angloamerican literature) is a hereditary leukokeratosis localised preferably in the oral mucosa, but may simultaneously manifest itself in other regions, e.g. perianally. We report the case of a 18-year old patient with a primarily and exclusively extraorally located nevus spongiosus albus mucosae of the vulva. The differential diagnosis and clinical as well as therapeutical problems of this extremely rare disease are discussed.

Adolescent↗