Search PubMed⌕ Search

Biomedical subjects

M Strauss

Publications and source records attributed to M Strauss.

At least 163 records · Page 9Linked to original sources
PubMed1991

Immortalization of human fetal sinusoidal liver cells by polyoma virus large T antigen.

Fetal sinusoidal liver cells were isolated from human liver explant cultures and transfected with pCMVLT, a plasmid containing the immediate early promotor of cytomegalovirus (CMV) and the large tumor antigen (LT) coding part of the polyoma virus (py) genome. Whereas nontransfected cells stopped proliferating after 4 weeks, the transfected sinusoidal cells were stimulated to divide more quickly without changes in their morphology. Up to now, cells have been permanently cultured for more than 18 months and passaged over 130 times, corresponding to around 400 generations. This allows them to be regarded as "immortalized" cells. The presence of LT protein in the cells has been documented by means of immunoprecipitation and immunofluorescence. Expression of the v. Willebrandt factor VIII was the main criterion for classifying the cell population as endothelial cells. The presence of cytokeratins 7, 8, and 18 in these cells underlines their close ontogenic and functional relationship to mesothelial cells. Sinusoidal endothelial cells (SECs) synthesize vimentin and the typical extracellular matrix components collagen IV and fibronectin, but are negative for laminin and entactin. We used immortalized SEC's in co-culture experiments with fresh fetal human hepatocytes and adult mouse hepatocytes. They promoted survival of both types of hepatocytes over a period of 8-10 weeks. Control human fetal liver explant culture cells survived for only 3-4 weeks, whereas control adult mouse liver cells retained vitality for 8-10 days only.

Antigens, Polyomavirus Transforming↗
PubMed1991

Allergic fungal sinusitis: problems in diagnosis and treatment.

Although first described in 1983, allergic Aspergillus sinusitis (AAS) has yet to gain wide recognition among otolaryngologists and pathologists. We have treated three patients with a history of asthma, nasal polyposis, and recurrent pansinusitis who fit the description of allergic Aspergillus sinusitis. Histopathologically, mucinous material with abundant eosinophils and Charcot-Leyden crystals ("allergic mucin") is interspersed with fungal hyphae. Immunologic characteristics include serum total immunoglobulin E (IgE) elevation, increased RAST classes, and cutaneous reactivity to molds. A retrospective analysis of the histopathology of 82 patients with chronic sinusitis was also undertaken. Eleven additional patients with classic allergic mucin were identified, but were found to be without evidence of fungal elements. The clinical features of all 14 patients are reviewed revealing the spectrum of disease. The difficulties of diagnosis and a therapeutic protocol which includes wide local debridement and postoperative use of systemic steroids are discussed.

Adolescent↗
PubMed1991

Guinea pig model of transplacental congenital cytomegaloviral infection with analysis for labyrinthitis.

Cytomegalovirus is the most frequently recognized cause of congenital viral infection and of viral induced congenital hearing loss. Histopathologic reports on temporal bones from nine congenitally infected infants have most often demonstrated an endolabyrinthitis. The guinea pig and its specific cytomegaloviruses have been studied extensively as a model of transplacentally acquired infection. However, to date no investigation has been performed on the inner ear of such congenitally infected animals. To determine if a congenital viral labyrinthitis occurs in these guinea pigs, a study was conducted in which pregnant Hartley and Strain 2 guinea pigs were injected intraperitoneally with virulent salivary gland passaged cytomegalovirus during the first, second, or third trimester. Various durations of gestation up to delivery were permitted and selected organs from the products were then studied with routine histologic and immunocytochemical methods and cell cultures to verify the presence of transplacental infection. The temporal bones were studied with routine histopathology as well as immunocytochemical methods to detect cytomegalovirus antigen. Over 190 products of conception studied in this fashion revealed no evidence of teratogenesis or labyrinthine infection. It is not clear why in the presence of viremia, which resulted in cytomegalovirus infection of multiple organs, the inner ears of these animals were apparently spared.

Animals↗
PubMed1991

Aspergillus otomastoiditis in acquired immunodeficiency syndrome.

The diagnosis and therapy of fungal infection in the paranasal sinuses of the immunocompromised host, including those with acquired immunodeficiency syndrome (AIDS), has been discussed in recent literature. However, only limited reports have been presented on otologic infection in AIDS patients. A review of 26 such patients with otologic disease included no cases of fungal otopathology. Our recent experience with two patients with Aspergillus otomastoiditis is presented. The extent of fungal infection in these cases was early-stage in one patient and late-stage in the other. The case histories, management, and outcomes are presented to provide insight into this previously unreported complication of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Changes in pyruvate dehydrogenase complex (PDHc) activity and [3H]QNB-receptor binding in rat brain subsequent to intracerebroventricular injection of bromopyruvate.

Pyruvate dehydrogenase complex (PDHc), a link between carbohydrate and acetylcholine metabolism, is a regulatory enzyme for glucose and neurotransmitter metabolism in the brain and is reduced in Alzheimer-diseased brain. To study functional consequences of an inhibition of PDHc on muscarinic receptor binding, bromopyruvate, a suicide inhibitor od PDHc, was injected intracerebroventricularly (icv) in rats. Bromopyruvate caused a reduction of PDHc activity in the 3 brain regions examined, however, reaching significance only in the cerebral cortex and the hippocampus and not in the striatum, 24 h after injection. 3, 6, and 12 weeks later, there was a normalization or transiently increased activity, respectively, of PDHc in these brain regions. No changes in concentrations of energy-rich phosphates could be demonstrated in the cerebral cortex 12 weeks after brompyruvate injection. The number of muscarinic receptors was significantly reduced in the cerebral cortex 12 weeks after injection. The data indicate that a transient reduction of brain PDHc activity in vivo is associated with a long-lasting reduction in muscarinic cholinergic receptors. Because comparable changes of PDHc and muscarinic receptors are found in dementia of Alzhemier type, the model of bromopyruvate inhibition of PDHc in rats is suggested to be useful for experimental dementia research.

Alzheimer Disease↗
PubMed1990

Accumulation of c-fos mRNA in rat hippocampus during acquisition of a brightness discrimination.

Training rats to attain a foot-shock-motivated brightness discrimination in a Y-maze results in an early and transient increase of hippocampal c-fos mRNA levels. Maximal accumulation was observed immediately after training, returning to basal levels during the following 2 h. A similar increase was obtained when rats were subjected to a pseudotraining with an equal number of runs, but with random pairing of the choice of bright and dark alleys with foot shock. It is suggested that induction of hippocampal c-fos mRNA expression is a necessary, but not sufficient, prerequisite for the formation of long-term memory trace. This early gene expression seems rather to correspond to an initial stage induced by complex stimulus presentation of both the training and the pseudotraining procedure. The subsequent late synthesis or processing of target proteins finally contributing to the formation of a permanent trace requires the action of further convergent signals to principal cells, probably mediating reward or emotional influences.

Animals↗
PubMed1990

Use of modified silicone tracheal cannula for obstructive sleep apnea.

Experience with the original Montgomery silicone tracheal cannulas in 47 patients with obstructive sleep apnea has been reported. Further experience with 10 obstructive sleep apnea patients who used modified silicone tracheal cannulas that permit periodic self-removal, cleaning, and reinsertion was analyzed. Two patients used the tube briefly and without complications. The remaining eight patients used the modified cannula for 18 to 24 months. The average number of office visits following insertion was three. Compared to the original cannulas, there were markedly fewer difficulties with granulations, infection, and tube malposition with the modified cannulas. The improvements make this modified device a useful tool worth further study in obstructive sleep apnea patients requiring tracheostomy.

Adult↗
PubMed1990

Immortalization and transformation of human fibroblasts by regulated expression of polyoma virus T antigens.

We have established conditions for the immortalization of human fibroblasts by the large T antigen of the rodent virus polyoma. This allows the mechanism of immortalization to be studied, without interference by transformation events, in cells with relatively stable chromosomes. Large T antigen could immortalize human fibroblasts if expression was driven by a heterologous promoter like the immediate early promoter/enhancer of cytomegalovirus or the inducible mouse mammary tumour virus (MMTV) promoter. Using the latter promoter and dexamethasone, three clones were obtained, the immortalized phenotype of which was strictly dependent on the induction of T-antigen expression. At least one of these clones became mortal after removal of the inducing agent. The expression of large T antigen was paralleled by PCNA gene expression, as shown by nuclear run-off transcription, whereas none of a number of other known proto-oncogenes was influenced in its activity. Immortalized fibroblasts were readily transformed by polyoma virus middle T antigen expressed from the MMTV promoter or by the activated c-Ha-ras oncogene. The reversibility of immortalization and transformation is considered.

Antigens, Polyomavirus Transforming↗
PubMed1990

The value of preoperative radiotherapy response to maximizing laryngeal conservation in early stage supraglottic carcinoma.

This study is a retrospective review between 1976 and 1986 of 12 patients with T1(1) and T2(11) NO supraglottic cancers which were managed by a method that utilized planned preoperative radiotherapy (45-51 Gy) to the primary and bilateral necks. If adequate tumor response (greater than 75% reduction in size) was noted by laryngoscopy, therapy was completed at levels of 65-70 Gy to the primary. If a lesser tumor response was noted, the patient underwent supraglottic laryngectomy. Six patients completed primary radiotherapy (RT-RT) and six patients underwent supraglottic laryngectomy (RT-SG). There was evidence of residual tumor in three of six RT-SG patients. No tumor recurred at any site. Laryngeal function was preserved in all patients. Absolute survival was 58% at 67 months. This approach is oncologically sound and permits maximal laryngeal conservation.

Adult↗
PubMed1990

Food from waste.

Explore the source record for details and available documents.

Communicable Disease Control↗
PubMed1990

Ozena revisited.

Primary atrophic rhinitis or ozena is a chronic nasal disease characterized by progressive atrophy of the nasal mucosa and underlying bone, accompanied by the formation of foul smelling, thick, dry crusts in the greatly enlarged nasal cavities. Although the incidence of ozena is greatly diminished in the western world, it is still encountered rarely and merits the attention of the ENT specialist. Hereditary, infectious, developmental, endocrine and nutritional factors have been implicated but the etiology of ozena still remains enigmatic. Numerous surgical and non-surgical methods have been advocated for treatment of ozena. We review our experience with 17 ozena patients in the past 20 years and discuss different modes of treatment. The relevant literature is reviewed.

Adolescent↗
PubMed1990

Cellular immortalization--an essential step or merely a risk factor in DNA virus-induced transformation?

Different activities of DNA viral gene products seem to be involved in the immortalization process, even in cases where continued presence of the viral genome does not seem to be required for the maintenance of the immortalized state of a cell. Immortalization, does not appear to represent a single event as implied earlier and several studies have shown that the process can be reversible. Polyomavirus large T antigen and HPV E7 (or E6 + E7) seem to possess all the activities required in vitro for immortalization of human cells, whereas one of the required activities--that defined in the two-step model as a rare mutagenic event which occurs during cellular crisis--is weaker in SV40 large T antigen and E1A. Viral functions that can activate PCNA expression (or repress Rb1 expression) have to be considered as pivotal activities in immortalization. Finally, the growth factor independence characterizing many immortalized cells could be a result of growth factor-like activities intrinsic to the viral proteins or could reflect their ability to induce autocrine growth mechanisms. These statements all relate to the first aspect of our initial hypothesis concerning cellular immortalization and in general substantiate it. Is immortalization an essential step in malignant transformation? There seems no a priori reason that transformation or tumorigenesis should depend upon cellular immortalization. Notably, many tumors appear to be mortal in culture. Growth factor independence or activation of DNA replication--essential features of immortalization--are probably of little importance for tumors in vivo where a crucial environment is supplied by the surrounding cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Transfection by DNA-nuclear protein HMG1 complexes: raising of efficiency and role of DNA topology.

We have developed a novel and efficient transfection method based on the introduction of foreign DNA into mammalian cells in form of complexes of vector DNA with the nuclear protein HMG1. In this study, it is shown that a stabilization of the complexes against dilution dissociation by addition of soluble CaCl2 or by excessive HMG1 enhances the transfection efficiency. Furthermore, there are no differences in the transfection abilities between the 3 topological DNA forms, viz., supercoiled, open relaxed and linear DNA, if delivered to cells as HMG1-DNA complexes. It is further shown that transfection-inactive complexes of the core histones with foreign DNA can be activated in transfection by the addition of HMG1.

Animals↗
PubMed1989

High level gene expression in mammalian cells by a nuclear T7-phase RNA polymerase.

Here we describe a novel expression system for mammalian cells which is based on transcription of hybrid genes containing T7 phage promoters by a T7 phage RNA polymerase targeted to the nucleus of the host cells. The RNA polymerase gene of T7 phage has been modified by substituting a sequence encoding the nuclear location signal of SV40 large T antigen for the N-terminal part of the polymerase gene. Expression of the modified gene is driven by the mouse metallothionein promoter in transfected mouse Ltk- cells resulting in high concentration of the polymerase in the nucleus. Nuclear T7 RNA polymerase directs efficient transcription of the cat gene under control of a T7 promoter. T7 constructs are expressed at a level at least 6 fold higher than the prototype pRSVcat. The unique properties of this heterologeous expression system are discussed.

Amino Acid Sequence↗