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Biomedical subjects

D Kaiser

Publications and source records attributed to D Kaiser.

At least 127 records · Page 7Linked to original sources
PubMed1990

Cell alignment required in differentiation of Myxococcus xanthus.

During fruiting body morphogenesis of Myxococcus xanthus, cell movement is required for transmission of C-factor, a short range intercellular signaling protein necessary for sporulation and developmental gene expression. Nonmotile cells fail to sporulate and to express C-factor-dependent genes, but both defects were rescued by a simple manipulation of cell position that oriented the cells in aligned, parallel groups. A similar pattern of aligned cells normally results from coordinated recruitment of wildtype cells into multicellular aggregates, which later form mature fruiting bodies. It is proposed that directed cell movement establishes critical contacts between adjacent cells, which are required for efficient intercellular C-factor transmission.

Bacterial Proteins↗
PubMed1990

C-factor: a cell-cell signaling protein required for fruiting body morphogenesis of M. xanthus.

During fruiting body development, the product of the csgA gene is necessary for cellular aggregation, for spore differentiation, and for gene expression that is initiated after 6 hr of starvation. From nascent wild-type fruiting bodies we have purified a polypeptide of 17 kd called C-factor, which, at approximately 1 to 2 nM, restores normal development to csgA mutant cells. C-factor activity is not recovered from extracts of unstarved, growing cells or csgA mutant cells. The amino acid sequence from purified C-factor demonstrates that it is the product of the csgA gene. C-factor is active over a narrow range of concentration and has properties of a morphogenetic paracrine signal.

Amino Acid Sequence↗
PubMed1990

Growth and product formation of actinomycetes cultivated at increased total pressure and oxygen partial pressure.

Influence of pressure (P) and oxygen partial pressure (PO2) on cultivation of various Streptomyces spp. and Micromonospora purpurea was examined in pressurized air-lift and stirred tank fermenters. The maximum PO2 was 2100 mbar. Growth and product formation of all cultures tested were markedly influenced by PO2 higher than 1000 mbar. There is evidence that wild strains are more oxygen tolerant than production strains. At a certain PO2 the metabolic activities of all cultures were inhibited. However, results obtained with S. aureofaciens and S. rimosus indicated an increase in specific product formation rate at elevated pressure. With increase in oxygen tension incorporation of oxygen into tetracycline molecules was enhanced. Since elevated oxygen tension can either show inhibiting effects or may be used for regulation of product formation and selectivity, the influence of PO2 should be determined in an appropriate experimental set-up for each process.

Aerobiosis↗
PubMed1990

Omental pedicle flap used to treat a bronchopleural fistula after diaphragma--pericardio-pleuropneumonectomy.

In a 47-year-old male patient a bronchopleural fistula was apparent 22 days after extended right-sided diaphragma-pericardio-pleuro-pneumonectomy for pleuramesothelioma. The thoracic cavity was infected. Rethoracotomy was performed and the fistula was closed using an omental pedicle flap. The bronchial stump became tight and the cavity fluid became sterile. No abdominal complications were seen. The patient died 8 months later from malignant pericardial infiltration. The ability of greater omentum to revascularize ischemic tissue, to absorb fluid and to resist local infection is proved and used in several subspecialities of surgery. Nevertheless the use of the greater omentum in the management of bronchopleural fistula has been rarely published. The reported case shows that the closure of a large bronchopleural fistula is possible by using the attributes of the omental tissue.

Bronchial Fistula↗
PubMed1990

Purification and properties of Myxococcus xanthus C-factor, an intercellular signaling protein.

C-factor, a Myxococcus xanthus protein that restores the developmental defects of a class of nonautonomous mutants resulting from mutation of the csgA gene, has been purified approximately 1000-fold from starved wild-type cells. The monomeric form of C-factor is a single polypeptide with a molecular mass of 17 kDa that can be solubilized by detergent from membrane components. Characterization by gel filtration and denaturing gel electrophoresis suggests that biologically active C-factor is a dimer composed of two 17-kDa monomers. Antibodies against a form of the M. xanthus csgA gene product overexpressed in Escherichia coli react with purified C-factor.

Bacterial Proteins↗
PubMed1990

Cell motility is required for the transmission of C-factor, an intercellular signal that coordinates fruiting body morphogenesis of Myxococcus xanthus.

There are striking similarities between the developmental phenotypes of two different mutant classes of Myxococcus xanthus. The first class, mglA mutants, are nonmotile under all conditions tested. The second class, csgA mutants, are motile but belong to a class of signal-defective developmental mutants that cannot develop alone but will develop when mixed with intact wild-type cells. Nevertheless, both csgA and mglA mutants fail to aggregate properly or to sporulate when induced to form fruiting bodies. An mglA mutation and a csgA mutation affect expression of a panel of lacZ fusions to developmental genes in the same way, indicating that nonmotile cells and csgA cells arrest development at a similar stage. One explanation for the similarity of developmental phenotypes between these mutants is that motility is required for the csgA-mediated cell interaction. In support of this hypothesis, we report that C-factor, a protein purified from nascent wild-type fruiting bodies based on its ability to rescue csgA mutant fruiting body development, also rescues sporulation and expression of beta-galactosidase from developmentally controlled lacZ fusions in mglA strains, apparently without restoring their motility. Wild-type levels of active C-factor can be purified from mglA cells, yet intact mglA cells do not rescue csgA cells upon cell-cell mixing. Intact wild-type cells are unable to restore the sporulation and beta-galactosidase expression of mglA mutants. These results support the hypothesis that donor and responder cell motility is required for C-factor transmission between cells during development.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Proteins↗
PubMed1990

Defects in fruiting body development caused by Tn5 lac insertions in Myxococcus xanthus.

Mutations caused by insertions of Tn5 lac that block development are rare. At least six of the eight mutations examined appeared to be regulatory. Three of these were found to disrupt social motility, suggesting a particular importance for this function. One other occurred in a known cell-cell interaction gene, bsgA, and the remaining two were located in genes operative early in the developmental program.

Cell Movement↗
PubMed1990

[Special diagnosis of pleural metastasis].

In 58% of cases diagnosis of pleural metastases is confirmed by identification of malignant cells in pleural effusions. Sensitivity of pleural punch biopsies ranges about the same. Combination of both methods increases success rate up to 75%. Thoracoscopy has a sensitivity of about 89%, charged with complications in 1.7%, and over-shadowed by a lethality of 0.08%. Classical thoracoscopy after Jacobäus has to be differentiated from Maassen's method, using the mediastinoscope. Highest success rates are achieved by means of diagnostics thoracotomy, which in fact is restricted to isolated cases, where previous methods proved unsuccessful.

Biopsy↗
PubMed1990

[Lung resection in arteriovenous fistula].

Arteriovenous fistulas of the lung occur as a disease limited to the lung, or as a pulmonary manifestation of hereditary Rendu-Osler-Weber's disease. Typical complications are haemoptysis, haemothorax and cerebral embolism. We report on 3 patients in whom arteriovenous fistulas of the lung were removed by wedge excision or lobectomy. One of them had already suffered cerebral infarction. The indication for operative removal of single lesions is always given with respect to the severe complications of this disease. Decrease of the right-to-left shunt volume can usually be achieved.

Adult↗
PubMed1990

[State of oral health with children and adolescents aged 10 to under 15 years in relation to selected social factors].

The analysis of the state of oral health in pupils aged 10 to under 15 years showed a still high caries-morbidity. The mouth hygiene and the state of gingiva were good. Comparisons between pain patients, children dentistry patients and orthodontic patients showed best results in orthodontic patients. The state of oral health was found to be influenced by the profession of the parents, the number of brothers and sisters and the success at school.

Adolescent↗
PubMed1990

[Indications for surgical treatment of pleural carcinosis].

In patients with pleural carcinosis the indication for operative treatment results from their signs and symptoms and from the diminution in quality of life. The functional operative risk should be minimal. Additional to the tumour manifestation limiting indication for operation must be excluded. The operation is indicated for patients with expanding effusions after ineffective pleurodesis, for patients with chambered effusions, for reduction in tumour size and to improve chemotherapeutic results, for alleviation of pain in expanding tumour masses, as well as by suspected pleural mesothelioma and by solitary tumour findings. The parietal pleura is resected to prevent fluid production. The visceral fine-decortication allows for reexpansion of the lung.

Adenocarcinoma↗
PubMed1990

[MRI of an intrathoracic malignant tumor invading the chest wall].

22 patients with intrathoracic malignant tumors suspected of invading the chest wall were examined with CT and MRI. Chest wall invasion was operatively confirmed in 19 cases and excluded in the other 3 cases. CT showed tumor infiltration of the chest wall in 14/19 cases, no morphological changes in 5/19 cases. Thoracic wall invasion was demonstrated by MR in all 19 cases. Typical MR finding of malignant invasion was local lesion within the chest wall showing high signal intensity in post-Gd T1-weighted images and in T2-weighted images. Reactive inflammatory changes as well as malignant infiltration of the pleura showed high signal intensity on enhanced T1-weighted images and on T2-weighted images.

Adult↗
PubMed1990

[Value of magnetic resonance tomography in Pancoast and other tumors with infiltration of the thoracic wall].

Twenty-two patients with intrathoracic malignancies and suspected Pancoast and "break-out" tumours were submitted to a comparative investigation using CT scanning and MRI to detect infiltration of the chest-wall. In the patients, the lesion had been confirmed at surgery, which revealed malignant infiltration in 19 cases, and excluded in filtration in 3 cases. In 14 out of 19 patients, the CT scan revealed tumourous involvement of the chest-wall, while in five out of 19 patients, no such involvement was detected. Using MR imaging, tumour infiltration was detected in all 19 patients. A reliable MR sign of tumour involvement was the detection of signal-intensive lesions within the chest-wall in T1-weighted images following the administration of Gd-DTPA, and in the T2-weighted images. In contrast, signal enhancement of the pleura was found both in tumour involvement and in inflammation. In suspected tumorous chest-wall invasion MR imaging can demonstrate tumour involvement of the chest-wall when CT is equivocal.

Adult↗
PubMed1990

[Tuberculous spondylitis--a contribution to the differential diagnosis of space-occupying lesions of the posterior mediastinum].

This report describes a 27-year-old male patient with advanced spondylitis tuberculosa, who, being suspected of having a malignant tumour, was submitted to a CT-guided biopsy. Treatment comprising CT-controlled insertion of a permanent drain, and antituberculous chemotherapy and dorsal stabilisation, was administered. A high-risk intervention (diagnostic and therapeutic thoracotomy with the attendant acute danger of paraplegia was avoided through the use of the most up-to-date imaging procedures available.

Adult↗
PubMed1990

[Mounier-Kuhn disease/tracheobronchomegaly].

This paper reports on a 45-year-old male patient with tracheobronchomegaly, a very rare pathological picture, which is thought to be associated with autosomal, recessive genetic transmission. Radiological, nuclear-medical and pulmonary function-analytical findings, together with treatment, are presented.

Bronchi↗
PubMed1989

Clinical risk factors for proliferative vitreoretinopathy.

We reviewed the records of all patients with rhegmatogenous retinal detachments examined and treated by a single surgeon (B.P.C.) at the University of Virginia, Charlottesville, between 1978 and 1984. Of the 607 eyes that satisfied the selection criteria, a preliminary chart review of outcomes found that 65 (10.7%) had proliferative vitreoretinopathy and 34 had macular puckers. From the remaining 508 eyes, 325 controls were randomly selected to match each case from within a time window. Thirty-six (55.4%) of the 65 patients with proliferative vitreoretinopathy had had unequivocal reattachment after a single procedure before the onset of proliferative vitreoretinopathy, and the only clearly identified technical difficulty that was significantly more common in the patients with proliferative vitreoretinopathy was the inability to identify a retinal break. Several other features of the rhegmatogenous retinal detachments that correlated with the development of postoperative proliferative vitreoretinopathy were identified, and stepwise discriminant analysis was used to ascertain which of these were more important. The strongest predictor was use of vitrectomy in management of the detachment. Following this in order of importance were the presence of preoperative proliferative vitreoretinopathy, preoperative choroidal detachment, and the amount of cryopexy required. Vitrectomy remained a strong predictor even when considered after adjustment for all other characteristics. These data suggest that proliferative vitreoretinopathy is not simply an iatrogenic disease, but it is more likely to occur in association with certain detachment features that either by themselves or through their management require prolongation of the retinal wound healing process.

Cryosurgery↗