Search PubMed⌕ Search

Biomedical subjects

M Strauss

Publications and source records attributed to M Strauss.

At least 127 records · Page 7Linked to original sources
PubMed1995

Regulated expression of the retinoblastoma susceptibility gene in mammary carcinoma cells restores cyclin D1 expression and G1-phase control.

The product of the retinoblastoma susceptibility tumour suppressor gene, pRb, is a negative regulator of cell proliferation. In order to investigate the interaction between pRb and the cell cycle machinery in more detail, a functional Rb gene was reintroduced into the Rb-deficient human mammary carcinoma cell line Bt549. Since constitutive high level expression of Rb turned out to be difficult to maintain, the tetracycline-dependent gene expression system was used. A number of clones was generated which all showed low level expression in the noninduced state. Considerable induction rates were obtained. The low level of noninduced Rb expression was sufficient to induce the expression of cyclin D1 the level of which was not further increased by upregulation of Rb expression. Concomittantly, an increase in cell doubling time was observed due to retardation of the cell cycle in the G1-phase. The data suggest that limiting amounts of cyclin D1 determine, at least partly, the extent of growth-repressing properties of pRb. The inducible system allows for maintenance of Rb-reconstituted cells at a low level of expression and for their use in the investigation of downstream functions of pRb.

Breast Neoplasms↗
PubMed1995

Temporal bone histopathology of cisplatin ototoxicity.

Cisplatin (cis-diamminedichloroplatinum II) is a potent chemotherapeutic agent that is useful in the treatment of a variety of malignancies. Ototoxicity is a well-known adverse side effect of this drug and has been widely described in reports on clinical and animal studies. Few human temporal bone studies, however, have been performed for cisplatin ototoxicity. This report presents four cases of cisplatin ototoxicity in patients from whom temporal bone specimens with minimal post-mortem autolysis were obtained at autopsy. All patients received between 1 and 6 cycles of cisplatin with doses ranging from 100 to 165 mg/M2 per cycle. None of the patients received significant amounts of aminoglycosides or loop diuretics. Histopathologic changes included loss of inner and outer hair cells in the basal turn of the cochlea, degeneration of the stria vascularis, and a significant decrease in spiral ganglion cells predominantly in the upper turns.

Adolescent↗
PubMed1994

The PRAD-1/cyclin D1 oncogene product accumulates aberrantly in a subset of colorectal carcinomas.

The PRAD-1/cyclin D1 proto-oncogene is localized on chromosome 11q13 and it is overexpressed in several tumour types as a consequence of gene amplification or chromosomal rearrangements. In this study, the abundance and patterns of cyclin D1 protein expression in normal/non-involved colon (n = 44), primary (n = 48) and metastatic (n = 9) colorectal carcinomas, and in a series of 4 colon cancer cell lines were investigated by immunochemical methods using the DCS-6 monoclonal antibody specific for cyclin D1. While examination of all normal colorectal tissue samples and 56% of the primary tumours revealed only weak to undetectable immunostaining signals, 23% of the primary carcinomas showed moderate and 21% showed strong aberrant accumulation of this cell-cycle regulatory oncoprotein. The immunohistochemical patterns in the secondary lesions were concordant with the matched primary tumours in all cases. The staining was nuclear both in the clinical specimens and in the colon cancer cell lines, in which the antibody-mediated knock-out experiments demonstrated a positive regulatory role of the cyclin D1 protein whose function was required for progression through the G1 phase of the cell cycle. These results indicate that the PRAD-1/cyclin D1 protooncogene may be deregulated in a significant subset of colorectal tumours, and warrant further analyses of such aberrations of the cyclin D1/retinoblastoma protein pathway to elucidate its potential involvement in the multistep pathogenesis of human colorectal cancer.

Chromosomes, Human, Pair 11↗
PubMed1994

Cyclin D1 protein expression and function in human breast cancer.

Cyclin D1 is a cell-cycle regulator essential for G1 phase progression and a candidate proto-oncogene implicated in pathogenesis of several human tumour types, including breast carcinomas. In spite of the accumulating genetic evidence, however, there are no data regarding abundance and properties of the cyclin D1 protein in breast cancer. We now report aberrant nuclear overexpression/accumulation of the cyclin D1 protein in about half of the 170 primary breast carcinoma specimens analyzed by monoclonal antibody immunohistochemistry, indicating that the frequency of cyclin D1 abnormalities may be considerably higher than previously deduced from DNA amplification studies. A comparison of the expression patterns in matched lesions at different stages of tumour progression revealed that the cyclin D1 protein aberration appears to reflect a relatively early event and that, when acquired by a tumour, it is maintained throughout breast cancer progression including metastatic spread. In both tumour tissues and breast cancer cell lines, the abundance of this protein shows characteristic variations consistent with a cell-cycle oscillation and the peak levels expressed in G1. In all 7 cell lines whose retinoblastoma (Rb) protein is mutant or complexed to SV40 T antigen, exceptionally low levels of cyclin D1 protein and mRNA were found. Antibody-mediated and anti-sense oligonucleotide knockout experiments demonstrate the requirement for the cell-cycle regulatory function of cyclin D1 in breast cancer lines with single or multiple copies of the gene and reveal the absence of such a requirement in the cell lines with Rb defects. Our data are consistent with the notion that the emerging "Rb-cyclin D1 pathway" represents a frequent target of oncogenic abnormalities in breast cancer.

Base Sequence↗
PubMed1994

Efficient transfer of antibodies into mammalian cells by electroporation.

An optimized protocol for electroporation is described which is suitable for introducing antibodies into mammalian cells. The method results in the uptake of detectable amounts of antibodies in 80% of the cells and in 40% large amounts are introduced. As an example, cell cycle activity (transition from the G1 to S phase) was inhibited by the introduction of monoclonal antibodies against G1-specific cyclin D1 into CV-1 and MCF7 cells. This specific antibody mediated inhibition of cellular function did not affect the viability of the cells since they recovered from the inhibition after some time. While approaching the efficiency of microinjection, the new protocol for electroporation of antibodies additionally permits treatment of the larger number of cells which are required for biochemical analyses.

Animals↗
PubMed1994

Cyclin D1 expression is regulated by the retinoblastoma protein.

The product of the retinoblastoma susceptibility gene, pRb, acts as a tumor suppressor and loss of its function is involved in the development of various types of cancer. DNA tumor viruses are supposed to disturb the normal regulation of the cell cycle by inactivating pRb. However, a direct function of pRb in regulation of the cell cycle has hitherto not been shown. We demonstrate here that the cell cycle-dependent expression of one of the G1-phase cyclins, cyclin D1, is dependent on the presence of a functional Rb protein. Rb-deficient tumor cell lines as well as cells expressing viral oncoproteins (large tumor antigen of simian virus 40, early region 1A of adenovirus, early region 7 of papillomavirus) have low or barely detectable levels of cyclin D1. Expression of cyclin D1, but not of cyclins A and E, is induced by transfection of the Rb gene into Rb-deficient tumor cells. Cotransfection of a reporter gene under the control of the D1 promoter, together with the Rb gene, into Rb-deficient cell lines demonstrates stimulation of the D1 promoter by Rb, which parallels the stimulation of endogenous cyclin D1 gene expression. Our finding that pRb stimulates expression of a key component of cell cycle control, cyclin D1, suggests the existence of a regulatory loop between pRb and cyclin D1 and extends existing models of tumor suppressor function.

Base Sequence↗
PubMed1994

Adult-onset otitis media with effusion.

OBJECTIVE: To document the prevalence of adult-onset otitis media with effusion (OME), and to determine its causes, diagnostic approach, and therapeutic management. DESIGN: A prospective study of 167 consecutive patients with adult-onset OME. Endoscopic examination of intranasal and nasopharyngeal structures with special attention to the eustachian tube orifices was performed in all patients. In 65 patients computed tomography of the skull base, neck, and paranasal sinuses was also performed. RESULTS: Paranasal sinus disease, predominantly of the ethmoid system, was found to be the dominant causal factor in 110 patients (66%). Smoking-induced nasopharyngeal lymphoid hyperplasia and adult-onset adenoidal hypertrophy, two entities herein described, were the cause of OME in 15 patients (19%). Various other causes were found in 31 patients. Head and neck tumors, mainly nasopharyngeal carcinomas, were found in only eight patients (4.8%). The cause of adult-onset OME could not be determined in three patients (1.8%). CONCLUSIONS: Contrary to common belief, adult-onset OME is not an uncommon disease. Nasendoscopy is the mainstay of diagnostic evaluation in most patients. Computed tomography is also an important tool in most selected cases. Appropriate treatment of sinusitis resulted in resolution of OME in most patients. Sinusitis is the most common causal factor of adult-onset OME, but nasopharyngeal and parapharyngeal space-occupying lesions should be ruled out in all cases.

Adolescent↗
PubMed1994

Structure of the gene coding for the human early lymphocyte activation antigen CD69: a C-type lectin receptor evolutionarily related with the gene families of natural killer cell-specific receptors.

CD69 is the earliest inducible cell surface glycoprotein acquired during lymphoid activation. CD69 functions as a signal transmitting receptor involved in cellular activation events including proliferation and the induction of specific genes. This molecule is a member of a supergene family of type-II integral membrane proteins with C-type lectin domains. We have herein studied the genomic structure of the human gene encoding CD69. The coding sequence is divided into five exons separated by four introns. The first two exons corresponded to separate functional domains of the protein (cytoplasmic tail and the transmembrane region), while the final three exons encoded the carbohydrate-recognition domain (CRD). The conserved intron position between the exons encoding the CRD indicated that this protein is closely related to other type-II receptor groups with the C-type CRD, such as the asialoglycoprotein receptors, the low-affinity IgE receptor (CD23), and natural killer cell-specific receptors, NKR-P1 and Ly49. In contrast to the broad NKR-P1 and Ly-49 gene families, CD69 is a single-copy gene, as demonstrated by Southern blot analyses. The major transcription initiation site has been located, by amplification of cDNA 5' ends, 30 nucleotides downstream of a consensus TATA box. Comparison of human CD69 and mouse NKR-P1 gene structures indicates that the first intron maintains a conserved position, suggesting that CD69 and this gene family may diverge from a common ancestor gene. A possible evolutionary pathway of these genes is proposed.

Antigens, CD↗
PubMed1994

Cell cycle-related variation and tissue-restricted expression of human cyclin D1 protein.

Recent evidence from genetic studies suggests that abnormalities of some of the members of the cyclin superfamily may be intimately associated with tumourigenesis, most likely through deregulation of the cell cycle control. In an attempt to elucidate the potential role of cyclin D1 (a gene located within the 11q13 amplicon and a candidate BCL-1, PRAD-1 oncogene) in the pathogenesis of human neoplasias, we have developed and characterized a novel monoclonal antibody specifically recognizing cyclin D1 protein in various assays including immunohistochemistry on frozen and paraffin sections. Using the DCS-6 antibody as a tool, we now show a characteristic cell cycle-dependent variation of the cyclin D1 protein in human cultured cells and report on the first immunohistochemical study of this G1 cyclin in a range of normal human tissues and breast carcinomas. Analysis of normal tissues revealed generally low levels of cyclin D1 protein, mainly restricted to the proliferative zones of some epithelial tissues, and the lack of its expression in several human tissues including lymph nodes, spleen, and tonsils. In contrast, pronounced overexpression/nuclear accumulation of cyclin D1 was found in 37 per cent of cases in a series of 35 primary ductal carcinomas of the breast. We conclude that the DCS-6 antibody provides a potentially useful tool for the establishment of simple methods suitable for verifying any diagnostic and/or prognostic value of this novel marker on large series of histological specimens and opens the way for biochemical, immunocytochemical, and immunohistochemical studies of the role played by cyclin D1 aberrations in human oncogenesis.

Animals↗
PubMed1994

DNA tumor virus oncoproteins and retinoblastoma gene mutations share the ability to relieve the cell's requirement for cyclin D1 function in G1.

The retinoblastoma gene product (pRB) participates in the regulation of the cell division cycle through complex formation with numerous cellular regulatory proteins including the potentially oncogenic cyclin D1. Extending the current view of the emerging functional interplay between pRB and D-type cyclins, we now report that cyclin D1 expression is positively regulated by pRB. Cyclin D1 mRNA and protein is specifically downregulated in cells expressing SV40 large T antigen, adenovirus E1A, and papillomavirus E7/E6 oncogene products and this effect requires intact RB-binding, CR2 domain of E1A. Exceptionally low expression of cyclin D1 is also seen in genetically RB-deficient cell lines, in which ectopically expressed wild-type pRB results in specific induction of this G1 cyclin. At the functional level, antibody-mediated cyclin D1 knockout experiments demonstrate that the cyclin D1 protein, normally required for G1 progression, is dispensable for passage through the cell cycle in cell lines whose pRB is inactivated through complex formation with T antigen, E1A, or E7 oncoproteins as well as in cells which have suffered loss-of-function mutations of the RB gene. The requirement for cyclin D1 function is not regained upon experimental elevation of cyclin D1 expression in cells with mutant RB, while reintroduction of wild-type RB into RB-deficient cells leads to restoration of the cyclin D1 checkpoint. These results strongly suggest that pRB serves as a major target of cyclin D1 whose cell cycle regulatory function becomes dispensable in cells lacking functional RB. Based on available data including this study, we propose a model for an autoregulatory feedback loop mechanism that regulates both the expression of the cyclin D1 gene and the activity of pRB, thereby contributing to a G1 phase checkpoint control in cycling mammalian cells.

Adenovirus E1A Proteins↗
PubMed1994

An assay for O6-alkylguanine-DNA alkyltransferase based on restriction endonuclease inhibition and magnetic bead separation of products.

We describe an improved, rapid and cost effective assay for measuring O6-alkylguanine-DNA alkyltransferase (AGT) levels in large numbers of small biological samples. The assay is based on the use of a synthetic O6-methylguanine oligonucleotide bound to magnetic beads via a biotin-streptavidin linkage and bound to its complement. A 35S label is incorporated into the free end of the duplex. The basis of the assay lies in the observation that the restriction enzyme PvuII will not cleave the bead-bound duplex oligonucleotide having an O6-methylguanine within the restriction sequence. However, on removal of the methyl group by AGT present in cell extracts prior to incubation with PvuII, the 35S-labelled oligonucleotide is cleaved by the restriction enzyme, releasing a 35S-labelled 8 bp fragment. Due to the stoichiometric nature of the AGT reaction, quantitation of AGT is easily achieved by counting an aliquot of the supernatant after pelleting the unrestricted bead complexes with a magnet. AGT levels measured in certain cell lines and human lymphocytes by the reported assay are comparable to other methods. The assay can be performed in basic laboratories and allows for the rapid processing of many samples simultaneously, which could prove useful in clinical and epidemiological studies.

Base Sequence↗
PubMed1994

Lymphoma of the nasolacrimal drainage system.

1. Primary lymphomas of the nasolacrimal system are rare. 2. Workup for suspected lesions should include careful history and physical examination, appropriate radiographic imaging including CT scanning, and adequate tissue biopsy. 3. Isolated lesions of the diffuse large cell subtype have a favorable prognosis with standard treatment modalities of either primary radiotherapy or chemotherapy. 4. Epiphora is an expected residual despite tumor control, and secondary dacryocystorhinostomy may be necessary.

Adult↗
PubMed1994

Airway obstruction in hemophilia (factor VIII deficiency): a 28-year institutional review.

Life-threatening airway compromise is rarely reported as a major complication of coagulation disorders. However, before adequate factor-replacement therapy became available, this complication was often fatal. A retrospective review of all patients with classic hemophilia admitted to our institution from 1964 through 1992 was performed. The records of 147 patients who had a total of 1804 admissions were examined. Fifteen episodes of airway obstruction occurred. Additionally, 6 cases of potential airway compromise and 5 cases of airway-endangering oropharyngeal bleeding were identified. Tracheotomy was performed in 5 patients; 1 fatality occurred before modern replacement products were available. Patients with this disorder have a 13% chance of some form of airway-endangering event with an 8% chance that it will be immediately life-threatening. Tracheotomy and subsequent decannulation are safe procedures in these patients.

Adolescent↗
PubMed1994

Local increase of beta 1-integrin expression in cocultures of immortalized hepatocytes and sinusoidal endothelial cells.

The expression and spatial arrangement of beta 1-integrins was determined on two immortalized liver cell lines held in coculture, namely the epithelial cell line mHepR1 and a sinusoidal endothelial cell line. On mHepR1 cells the distribution of beta 1-integrins was restricted to the basolateral plasma membrane domains, a staining pattern that is typical of polarized epithelial cells. On the endothelial cell line the beta 1-integrins were distributed all over the cell surface. In coculture the endothelial cells tended to cover over the epithelial cells. Epithelial cells located in their vicinity exhibited an increased staining of beta 1-integrins at basolateral plasma membrane domains, which was most prominent with regard to the alpha 2-subunit. When mHepR1 cells were cultivated on various types of extracellular matrix also synthesized by the endothelial cells only collagen IV was found to increase the intensity of beta 1-integrin expression at the cell surface. The results indicate that beta 1-integrin expression in epithelial cell colonies can locally be modulated by interactions with non-parenchymal cells. In addition, the data suggest that mHepR1 cells may be a favorable system for analyzing basic functions of beta 1-integrins in polarized epithelial cells.

Aldehydes↗
PubMed1994

Liver-directed gene therapy: prospects and problems.

The development of strategies for gene therapy in the liver is a challenging task because this organ is particularly involved in the manifestation of numerous genetic diseases as well as in malignant and infectious diseases. Most of the available techniques for gene transfer were already applied to hepatocytes ex vivo. Attempts to retransplant retrovirally transduced hepatocytes back to patients have shown the limits of the ex vivo approach. The obvious alternative would be the development of suitable techniques for gene transfer in vivo. Both viral and non-viral delivery systems were tested in animal models with limited success. This article summarizes the state of the art of the available techniques and vectors and discusses the essential future developments.

Adenoviridae↗