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Biomedical subjects

C Hartmann

Publications and source records attributed to C Hartmann.

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

Neutral endopeptidase: variable expression in human lung, inactivation in lung cancer, and modulation of peptide-induced calcium flux.

Neutral endopeptidase (NEP; CALLA, CD10, EC 3.4.24.11) is a cell surface endopeptidase that hydrolyses bioactive peptides, including the bombesin-like peptides, as well as other neuropeptides. Bombesin-like peptides and other neuropeptides are autocrine growth factors for both small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Low expression of NEP has been reported in SCLC and NSCLC cell lines. NEP inhibition has been shown to increase proliferation in one cell line. To date, NEP expression has not been quantitatively evaluated in normal adult lung, SCLC or NSCLC tumors, paired uninvolved lung from the same patient, or in other pulmonary neoplasms such as mesotheliomas and carcinoids. We examined the expression of NEP in these tissues and human cell lines using immunohistochemistry, flow cytometry, enzyme activity, ELISA, Western blot, and reverse transcription (RT)-PCR. Uninvolved lung tissue from different individuals displayed considerable variation in NEP activity and protein. By immunohistochemistry, NEP expression was detectable in alveolar and airway epithelium, fibroblasts of normal lung, and in mesotheliomas, whereas it was undetectable in most SCLC, adenocarcinoma, squamous cell carcinoma, and carcinoid tumors of the lung. NEP activity and protein levels were lower in all SCLC and adenocarcinoma tumors when compared to adjacent uninvolved lung, often at levels consistent with expression derived from contaminating stroma. NEP expression and activity were reduced or undetectable in most SCLC and lung adenocarcinoma cell lines. NEP mRNA by RT-PCR was not expressed or was in low abundance in the majority of lung cancer cell lines. The majority of lung tumors did not express NEP by RT-PCR as compared with normal adjacent lung. In addition, recombinant NEP abolished, whereas an NEP inhibitor potentiated, the calcium flux generated by neuropeptides in some lung cancer cell lines, demonstrating potential physiological significance for low NEP expression. NEP, therefore, is a signal transduction and possibly a growth modulator for both SCLC and NSCLC, emphasizing the role of neuropeptides in the pathogenesis of the major histological forms of lung cancer.

Adenocarcinoma↗
PubMed1996

Structure-activity relationships of a new family of steroidal aromatase inhibitors. 1. Synthesis and evaluation of a series of analogs related to 19-[(methylthio)methyl]androstenedione (RU54115).

During the course of a study aimed at the search for new potent aromatase inhibitors, several new androstenedione analogs were synthesized and evaluated. This study led to the discovery of 19-[(methylthio)methyl]androsta-4,9(11)-diene-3,17-dione (7; RU54115) already described by our laboratory. The object of the present series of papers is to disclose the result of the structure-activity relationship studies that gave rise to this compound. This first part deals mainly with the substitution in the 19-position of the steroid nucleus. Several parameters were varied, the length of the chain and its rigidity and branching, as well as the nature of the heteroatom itself and its substitution. The interaction of these new compounds with human placental aromatase in competition with the substrate androstenedione was studied by difference visible spectroscopy. The in vivo aromatase-inhibiting activities were evaluated by measuring the estradiol lowering after oral administration of the compounds to PMSG-primed female rats.

Animals↗
PubMed1996

Intramolecular recombination of a mitochondrial minicircular plasmid-like DNA of date-palm mediated by a set of short direct-repeat sequences.

A molecular clone containing the complete sequence of a mitochondrial circular plasmid-like DNA (the R plasmid) isolated from the date-palm variety V3DP was used as a probe in Southern analyses of mitochondrial DNA prepared from other varieties. Another circular structure (the S plasmid) was detected in some of these varieties, and sequenced from variety V2DP. It appears that the R plasmid could have arisen from the S plasmid by an intermolecular recombination event at a set of 26-bp imperfect short direct repeats.

Base Sequence↗
PubMed1996

[New communication media for ophthalmology].

BACKGROUND: The use of high-tech communication is undoubtedly growing and has become established in almost all sciences and research fields. This article surveys the possibilities for scientific data-exchange via the Internet, the world's largest computer network. METHODS: An introduction is given to network as a whole, its history and structure, and the hardware and software required. Examples are provided to describe the basic services on the Internet with special emphasis on World wide web applications. CONCLUSIONS: The paper indicates that the Internet has a vast potential for providing almost unlimited information of relevance to users. By using the Internet and its resources, modern ophthalmological research will become more effective and successful.

Computer Communication Networks↗
PubMed1996

The immunology of bullous oculo-muco-cutaneous disorders.

In skin-blistering diseases, alteration of cellular adhesion results in a loss of cohesion of the epithelium of the skin and the mucous membranes. These disorders are often genetically determined and involve highly specific autoantibodies. A recent workshop discussed the immunology of these diseases.

Eye Diseases↗
PubMed1996

[Autoimmune diseases of the peripheral cornea. Immunopathology, clinical aspects and therapy].

Noninfectious ulceration of the peripheral cornea remains a major diagnostic and therapeutic challenge. The pathogenesis in most of these disorders is unclear, however, on the basis of systemic connective tissue diseases, autoimmune mechanisms are most likely involved. The peripheral cornea has distinct morphological and immunological characteristics that predispose for inflammatory reactions. Major differences exist regarding humoral and cellular components of the immune system. In the peripheral cornea there is more high-molecular IgM and initial complement component C1 than in the central cornea and may predispose for immune complex formation. The close contact to the conjunctival vasculature provides the basis necessary to generate an immune response. Langerhans cells and macrophages as important antigen presenting and processing cells are present in higher number in the peripheral cornea. Autoimmune diseases that affect the peripheral cornea include collagen vascular diseases and Mooren's ulcer. Although this association is obvious in advanced rheumatoid arthritis more subtle forms of polyarteritis nodosa or systemic lupus erythematosus require careful medical evaluation and workup. Ocular manifestations may present as the initial clinical signs and require careful workup in these potentially lethal disorders.

Antigen-Presenting Cells↗
PubMed1996

[Pathogenesis of complicated cataract in herpetic kerato-uveitis].

BACKGROUND: Keratitis, retinitis and secondary cataract are well known complications of ocular herpes simplex infection. We report on a case of herpetic keratouveitis and cataract. Acute and inflammatory pathogenesis of cataract formation resemble a phacoanaphylactic reaction. CASE REPORT: A 15-year-old girl with recurrent herpes keratitis was referred for acute spontaneous cataract formation accompanied by iridocyclitis and hypotony. Visual acuity was decreased from 0.4 to light projection. During cataract extraction the anterior chamber was tabbed for immunological analysis. The thickened anterior lens capsule was examined by light microscopy. We found a significant local synthesis of herpes antibodies in the aqueous. Histologically the lens capsule depicted a defect and a granulomatous inflammatory infiltrate towards the basal membrane material. The specimen was not suitable to judge on eventual additional phacoanaphylaxis. After cataract extraction and systemic acyclovir and corticosteroids the keratouveitis subsided. Visual acuity improved to 0.4, but was limited by the disciform corneal scar. CONCLUSION: The granulomatous response towards lens capsule shown here, resembles the granulomatous reaction towards Descemet's membrane in advanced herpetic corneal ulcer. We speculate on the pathogenesis of the lens capsule defect as a, so far unknown, herpes-associated autoimmun response against the basal membrane material of the lens. The acuteness of cataract formation may be a consequence of contact of aqueous with lens fibres. Additional phacoanaphylaxis combined with secondary glaucoma is possible.

Acyclovir↗
PubMed1996

[Effects of human recombinant basic Fibroblast Growth factor on endothelial wound healing in organ culture of human cornea].

PURPOSE: The effects of human recombinant bFGF has been evaluated on 9 paired human donor corneas (age 75 +/- 8 years), preserved in organ culture medium. MATERIAL AND METHODS: The endothelium of corneas were mechanically wounded (area of 7.53 +/- 2.05 mm2) and placed in culture medium during 14 days. For each pair, one cornea was tested with bFGF (50 ng/ml), delivered in two times (day 0, day 7), according to the stockage of the bFGF on the basal membranes (low affinity receptor), while the ipsilateral cornea served as control. Endothelium was assessed by trypan staining at day 0, day 7, and day 14. At this term of fourteenth day, alizarine red and trypan blue staining permitted morphometric data. RESULTS: The bFGF factor increases significantly cell density in the wound area (p < 0.05), and in the transitional area (p < 0.01), compared to the control group. In the transitional area, cells depletion was only 15% (392 +/- 55 cells/mm2) in the treated group compared to the 28% (716 +/- 0.1 cells/mm2) in the untreated group. In the wound area, the mean cell area was averaged 2581 microns2 in the control group and 2161 microns2 in the bFGF treated group (p < 0.05); in the transitional area the mean cell size was 549 microns2, and 479 microns2 in the control and the bFGF treated group (p < 0.05) respectively. The bFGF group do not affect the shape factor. CONCLUSION: This assay demonstrates that human bFGF greatly facilitates wound closure in endothelium of human cornea. The cellular migration from the transitional zone seems the dominant healing mechanism.

Cell Count↗
PubMed1996

Specular microscopy: from speculative to spectacular microscopy.

The evolution of confocal microscopy for in vivo qualitative analysis of the cornea seems to follow a path similar to that followed by specular microscopy after its reintroduction almost 20 years ago. The purpose of this report is to present the evolution of our own research data, starting with speculation concerning the attribution of morphological features and finishing with cell-to-cell correlation with special techniques. We present representative clinical but mainly experimental data from relocation studies using flat preparation, especially developed sequential vital staining techniques, and scanning electron microscopy as compared with specular microscopy. Starting from speculative attribution of the observed morphological features, we were capable of classifying morphological data on the endothelium and the surrounding structures into preendothelial, endothelial, retroendothelial, and non-endothelial features. Specular microscopy allows the detailed study of cellular and even intracellular structures and is probably one of the most spectacular ways of doing noninvasive in vivo microscopy in humans.

Endothelium, Corneal↗
PubMed1995

The Drosophila fork head domain protein crocodile is required for the establishment of head structures.

The fork head (fkh) domain defines the DNA-binding region of a family of transcription factors which has been implicated in regulating cell fate decisions across species lines. We have cloned and molecularly characterized the crocodile (croc) gene which encodes a new family member from Drosophila. croc is expressed in the head anlagen of the blastoderm embryo under the control of the anterior, the dorsoventral and the terminal maternal organizer systems. The croc mutant phenotype indicates that the croc wild-type gene is required to function as an early patterning gene in the anterior-most blastoderm head segment anlage and for the establishment of a specific head skeletal structure that derives from the non-adjacent intercalary segment at a later stage of embryogenesis. As an early patterning gene, croc exerts unusual properties which do not allow it to be grouped among the established segmentation genes. A single-site mutation within the croc fkh domain, which causes a replacement of the first out of four conserved amino acid residues thought to be involved in the coordinate binding of Mg2+, abolishes the DNA binding of the protein in vitro. In view of the resulting lack-of-function mutant phenotype, it appears likely that metal binding by the affected region of the fkh domain is crucial for proper folding of the DNA-binding structure.

Amino Acid Sequence↗
PubMed1995

Horseradish peroxidase Phe172-->Tyr mutant. Sequential formation of compound I with a porphyrin radical cation and a protein radical.

A gene coding for the F172Y mutant of horseradish peroxidase isozyme C (HRP) has been constructed and expressed in both Spodoptera frugiperda (SF-9) and Trichoplusia ni egg cell homogenate (HighFive) cells. Homology modeling with respect to three peroxidases for which crystal structures are available places Phe172 on the proximal side of the heme in the vicinity of porphyrin pyrrole ring C. The pH optimum and spectroscopic properties of the F172Y mutant are essentially identical to those of wild type HRP. Vmax values show that the mutant protein retains most of the guaiacol oxidizing activity. Stopped flow studies indicate that Compound I is formed with H2O2 at the same rate (kappa 1 = 1.6 x 10(7) M-1 s-1) at both pH 6.0 and 8.0 as it is with the wild type enzyme. This Compound I species decays rapidly at a rate kappa 2 = 1.01 s-1, pH 7.0, to a second two-electron oxidized species that retains the ferryl (FeIV = O) absorption. EPR studies establish that a ferryl porphyrin radical cation is present in the initial Compound I, but electron transfer from the protein results in formation of a second Compound I species with an unpaired electron on the protein (presumably on Tyr172). The presence or absence of oxidizable amino acids adjacent to the heme is thus a key determinant of whether the second oxidation equivalent in Compound I is found as a porphyrin or protein radical cation.

Animals↗
PubMed1995

The role of exogenous/endogenous basic fibroblast growth factor (FGF2) and transforming growth factor beta (TGF beta-1) on human corneal endothelial cells proliferation in vitro.

Adult human corneal endothelial cells (HCEC) have extremely low turnover rates but undergo rapid division in vitro when stimulated with soluble growth factors. We have investigated the role played by FGF2 and TGF beta-1 in the regulation of HCEC growth stimulation. HCEC from donors who were over 30 years old were cultured and experiments performed on cultures between the 2nd and the 6th passage in the presence of 5% NCS. Cell counts revealed a maximal stimulation of 2.1x for FGF2 and 1.9x for TGF beta-1 compared to control cultures. When both factors were added, a synergistic effect was noticed with a maximal stimulation of the proliferation rate of 4.5x over controls. In addition, endogenous FGF2 produced by HCEC was quantitated in a sensitive EIA assay. After 5 days in culture, 10(6) cells contained 150 ng FGF2 and 35 ng was extracted from trypsin-digested ECM. Two molar NaCl washes of ECM released 15.6 ng FGF2, which induced a slight mitogenic activity (1.5x over control) in HCEC cultures, which was partially inhibited by an anti-FGF2 antibody. Northern blot analysis of HCEC extracts revealed the presence of FGF receptors R1 and R2 mRNA. The bioactive FGFRs were demonstrated by the toxic effect of a mitotoxin FGF2-SAP. These results suggest that FGF2 could participate in the autocrine regulation of HCEC proliferation and survival. The synergy between exogenously added FGF2 and TGF beta demonstrates that a combination of different growth factors may be important to stimulate proliferation of these cells in vivo.

Adult↗
PubMed1995

Spatiotemporal relationships between a novel Drosophila stripe expressing gene and known segmentation genes by simultaneous visualization of transcript patterns.

We describe the cloning of the Drosophila transcription unit odd-striped (ost), which maps close to the P-element insertion site of the enhancer-trap line 05279. In order rapidly to gain information on its chromosomal localization, and to determine the spatial and temporal expression patterns of ost in whole-mount embryos, we established a double-label in situ hybridization protocol to localize two different DNA or RNA sequences simultaneously. The double-label in situ hybridization method involves digoxigenin- and biotin-labeled DNA probes that are processed to result in blue alkaline phosphatase and brown peroxidase reaction products, respectively. Using reference probes as internal standards, we show that the ost transcription unit is located within the cytogenetic band interval 89A1,2 on the right arm of the third chromosome, and that it exerts diagnostic segmentation gene expression patterns in the embryo. The ost transcripts are initially expressed in an anterior cap at the blastoderm stage, followed by a transient pair-rule gene expression pattern, which eventually changes into a segmental polarity gene pattern at gastrulation. Our results establish detailed spatial and temporal relationships between ost expression and the known patterns of the segmentation genes fushi tarazu and wingless, and demonstrate the potential of the double-label method with differently tagged DNA probes.

Animals↗
PubMed1995

Corneal wound healing modulation using basic fibroblast growth factor after excimer laser photorefractive keratectomy.

Photorefractive keratectomy with the 193-nm excimer laser is one of the most promising innovations in refractive surgery. However, routine clinical application is hindered by two main obstacles, i.e., postoperative subepithelial opacity and possible regression of the refractive result. Because we have previously demonstrated beneficial effects of basic fibroblast growth factor (bFGF) on corneal epithelial healing in different in vivo models, we investigated the influence on both epithelial and stromal healing of topical bFGF after excimer laser keratomileusis in a rabbit model. After 7-mm circular deepithelialization, the eyes of 24 New Zealand White rabbits received identical deep stromal laser ablations (depth 50 microns, 6 D, diameter 5 mm) and were randomly assigned to one of four treatment groups [control (phosphate-buffered saline, PBS), bFGF 10 micrograms/application, dexamethasone 0.1%, bFGF + dexamethasone, n = 12 eyes/group]. All treatments were administered four times daily--bFGF until complete epithelial healing, dexamethasone and PBS until 3 months postsurgery. Wound surface regression on time was determined by means of computer-assisted image analysis of fluorescein-stained corneas. Corneal opacity was observed biomicroscopically and graded using a previously established scoring system. After bFGF application for 2-3 days only, a highly significant acceleration in epithelial wound healing speed was found compared with the rate of the other three treatment groups (p < 0.001). A combined therapy (bFGF + steroid) had no effect on the healing rate. Compared with control values, mean scores for subepithelial haze in the other groups were found to be nearly 50% lower during the first 2 postoperative months.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Altered immunohistochemical expression of small proteoglycans in the tumor tissue and stroma of basal cell carcinoma.

Small proteoglycans have been shown to act as receptors for matrix molecules or growth factors and to influence the attachment and the migration of cells. We therefore report here on the immunocytochemical expression of three small proteoglycans, i.e., decorin, biglycan, and the recently described PG-100, in normal human skin and in basal cell carcinoma. In normal human skin, staining for decorin revealed expression throughout the dermis with an increased signal in the papillary dermis, whereas no expression was observed in the epidermis. Biglycan and PG-100 were mainly detected in the epidermis, with biglycan being expressed only in suprabasal layers. In addition, biglycan could be detected in a narrow zone below the basement membrane. In tissue specimens obtained from 12 basal cell carcinomas, the expression of biglycan and PG-100 was absent or strongly down-regulated in the tumor tissue. Tumor cells thus displayed a staining pattern similar to that found on the basal cells of normal human skin. In the stroma surrounding the tumor, however, the expression of biglycan and to a lesser degree decorin was increased when compared with normal human dermis. The increased deposition appears to be due to an increased synthesis of these molecules, as total RNA extracted from basal cell carcinoma tissue revealed an induction of biglycan and decorin mRNA. This study indicates that the expression of proteoglycans in basal cell carcinoma tumor cells and in tumor stroma is altered from that in normal skin.

Animals↗
PubMed1994

Gene expression mediated by bacteriophage T3 and T7 RNA polymerases in transgenic trypanosomes.

Messenger RNAs of higher eukaryotes share a functionally essential 5' monomethyl CAP structure generated during a reaction that is linked exclusively to RNA polymerase II transcription. In unicellular parasites belonging to the Kinetoplastida, however, mRNAs acquire their 5' CAP through a trans-splicing reaction which effectively uncouples pol II transcription and capping. Consequently functional mRNAs can be produced by endogenous RNA polymerase I. Here we demonstrate the extension of this flexibility to heterologous bacteriophage polymerases. Transgenic Trypanosoma brucei cell lines stably expressing functional, nuclearly localized T3 or T7 RNA polymerase were established and assayed using reporter plasmids bearing the corresponding phage promoters. In these cell lines the levels of phage promoter-driven gene expression ranges from one half to greater than 5 times that mediated by endogenous pol I. Analysis of 5' ends of transcripts synthesized by the T7 polymerase revealed that they are trans-spliced. Thus the usual eukaryotic link between mRNA production and pol II transcription can be by-passed by the introduced phage polymerases, thereby significantly expanding the critically small panel of promoters currently available for exploitation in reverse genetic approaches in T. brucei.

Animals↗