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Biomedical subjects

N Roos

Publications and source records attributed to N Roos.

At least 91 records · Page 5Linked to original sources
PubMed1992

Differentiation of benign from malignant superficial lymphadenopathy: the role of high-resolution US.

Ultrasonography has proved a valuable tool for the detection of enlarged lymph nodes; however, differentiation between benign and malignant nodal disease remains a problem. High-frequency probes with improved spatial and contrast resolution display superficial nodes to advantage and also show the internal structure of the nodes. Ninety-four superficial nodes in patients with suspected nodal disease were examined by using 7.5-MHz probes to evaluate longitudinal-transverse diameter ratio (L/T), the central hilus, cortical widening, and size. Histologic diagnosis was obtained after sonographic examination in 73 nodes (five reactive nodes, 35 primary nodal malignancies, and 33 nodal metastases). The remaining 21 nodes regressed after either antibiotic or no therapy. Marked differences were observed among the proportions of benign and malignant nodes in terms of L/T, hilus, and cortex; the latter two structures, however, must be interpreted together. Eccentric cortical widening was seen in only malignant nodes. The distribution of nodal size was not significantly (P greater than .1) different for benign and malignant nodes. No differences were observed between primary and secondary nodal malignancies. The sonographic criteria evaluated in this study assist in the differentiation of benign from malignant superficial lymph nodes.

Adult↗
PubMed1992

Role of liver endothelial and Kupffer cells in clearing low density lipoprotein from blood in hypercholesterolemic rabbits.

The role of liver endothelial and Kupffer cells in the hepatic uptake of cholesterol-rich low density lipoprotein (LDL) was studied in rabbits fed a diet containing 2% (w/w) cholesterol for 3 weeks. 125I-labeled tyramine cellobiose-labeled cholesterol-rich LDL was injected intravenously into rabbits, and parenchymal and nonparenchymal liver cells were isolated 24 h after injection. The hepatic uptake was 9 +/- 3% of injected dose in cholesterol-fed rabbits 24 h after injection, as compared to 36 +/- 9% in control-fed rabbits (n = 6 in each group; significant difference, P less than 0.005). Endothelial and Kupffer cells took up 2.7 +/- 0.5% and 1.2 +/- 0.8% of injected dose in the hypercholesterolemic rabbits, as compared to 1.9 +/- 0.8% and 0.8 +/- 0.3% in control animals. The amount accounted for by the parenchymal cells was markedly reduced in the cholesterol-fed rabbits to 7.3 +/- 2.7% of injected dose, as compared to 32.8 +/- 7.6% in controls (P less than 0.02). On a per cell basis, the nonparenchymal cells of cholesterol-fed rabbits took up as much LDL as the parenchymal cells (0.6 +/- 0.2, 0.7 +/- 0.1, and 0.6 +/- 0.4% of injected dose per 10(9) parenchymal, endothelial, and Kupffer cells, respectively). This is in marked contrast to the control animals, in which parenchymal cells took up about 6 times more LDL per cell than endothelial and Kupffer cells (3.2 +/- 0.9, 0.7 +/- 0.3, and 0.5 +/- 0.1% of injected dose per 10(9) cells). Thus, 30% of the hepatic uptake of LDL in the cholesterol-fed rabbits took place in nonparenchymal cells, as compared to 6% in controls. Consistent with these data, the concentrations of cholesteryl ester in endothelial and Kupffer cells in rabbits fed the high cholesterol diet were about twofold higher than in parenchymal cells (428 +/- 74 and 508 +/- 125 micrograms/mg protein, respectively, vs. 221 +/- 24 micrograms/mg protein in parenchymal cells). In contrast to cells from normal rabbits, Kupffer and endothelial cells from cholesterol-fed rabbits accumulated significant amounts of Oil Red O-positive material (neutral lipids). Electron microscopic examination of these cells in situ as well as in culture revealed numerous intracellular lipid droplets. Slot blot hybridization of RNA from liver parenchymal, endothelial, and Kupffer cells showed that cholesterol feeding reduced the level of mRNA specific for the apoB,E receptor to a small and insignificant extent in all three cell types (to 70-80% of that observed in control animals).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

[Legionnaires' disease in intensive care patients. Results of plain film thoracic radiography].

We reviewed the chest radiographs and clinical data of 30 patients in an intensive care unit with legionellosis diagnosed by significant serological findings (n = 18), microscopic demonstration of the organism in the transtracheal aspirate (n = 5) or both (n = 7) and investigated the correlation between the identification of Legionella and signs of pulmonary infection. In 13 patients legionnaires' disease was diagnosed with a high degree of confidence. Typical radiographic findings included distal air space disease, which initially appeared to be unilateral, progressing towards bilateral infiltrates. Patchy infiltration at the onset of disease was followed by consolidation. Small pleural effusions were common, while no abscess formation was observed. Characteristically, infiltration persisted for weeks even with clinical convalescence. These radiological findings correspond well with observations in otherwise healthy patients with legionnaire's disease. In 10 patients the etiology of pulmonary infiltrates could not be identified. Seven patients did not develop radiological or clinical signs of pneumonia; therefore, the serological/microscopic detection of Legionella was not interpreted as legionnaires' disease. According to the results of our investigation the diagnosis of legionnaires' disease requires radiological findings in addition to laboratory data.

Adolescent↗
PubMed1991

[A comparison between digital luminescence radiography and conventional myelography].

The potential of digital luminescence radiography in replacing conventional myelography was analyzed using ROC methodology. 95 conventional (CR), digital (DR) and edge enhanced digital (EDR) myelograms (49 disk herniations, 46 normal) were read independently by 5 radiologists; and a ROC analysis was performed. Higher confidence levels were used in making both correct and incorrect diagnoses with DR and EDR than with CR. However, no statistically significant differences between AUC (area under the curve) values obtained with the different techniques, were noted. The separate analysis of cervical and lumbar myelograms showed no significant differences between the different techniques. With DR and EDR, the sensitivity of 4 of 5 readers was somewhat higher in the lumbar but lower in the cervical region than with CR. Replacement of conventional by digital luminescence myelography seems possible; however, some decrease of sensitivity in the cervical region must be accepted.

Humans↗
PubMed1991

[Diagnostic imaging of the salivary glands in children and adolescents].

In children and adolescents, imaging of the salivary glands is a valuable supplement to clinical examination in various diseases. The choice of the most appropriate radiological technique depends on patient compliance, the necessity of avoiding radiation exposure as far as possible, and the tentative diagnosis made on the basis of the clinical examination. Ultrasonography (US) is the method of choice for the detection of both acute inflammatory disease and masses in the salivary gland and the adjacent tissue. US can also be implemented as a screening method for calculi, though sialography is superior for this purpose. Sialography is the only technique that allows diagnosis and evaluation of the degree of chronic inflammation. Computed tomography and magnetic resonance imaging are required for more deeply located neoplasms of the parotid region.

Adolescent↗
PubMed1991

[Diagnostic validity of imaging methods in the detection and observation of the progress of cases of invasive aspergillosis of the blood vessels of the lung].

Chest radiographs and thoracic computed tomograms (CT) of 21 patients with oncologic disease and vasoinvasive pulmonary aspergillosis (PA) were assessed and compared. CT findings were interpreted by comparison with histologic lung specimens of 28 lethal cases of PA. The analysis showed that in the early stages of infection findings suggestive of PA were only found in 29% of cases (n = 6) on conventional radiographs, whilst CT suggested the presence of PA in all cases (n = 21). In advanced stages, conventional radiographs suggested the presence of PA in 38% of cases (n = 8), which was not significantly different from that value for early disease. The comparison of CT with histopathologic findings allows their objective interpretation; such studies provide an improvement in both detection rate and characterization of CT changes in PA.

Adolescent↗
PubMed1991

Endocytosis of the recombinant tissue plasminogen activator alteplase by hepatic endothelial cells.

The glycoprotein tissue-type plasminogen activator (t-PA, alteplase, CAS 105857-23-6) is a serine protease consisting of 527 amino acids and can activate plasminogen to plasmin, which subsequently dissolves the fibrin network of a thrombus. This activation occurs selectively on the thrombus, making recombinant t-PA a very effective agent in the treatment of thromboembolic disorders. t-PA has a short in vivo half-life and is rapidly removed from the circulation by the liver. The catabolism of t-PA involves receptor-mediated endocytosis and intracellular degradation in several cell types of the liver namely hepatic endothelial, parenchymal and Kupffer cells. Liver endothelial cells have been reported to possess a specific uptake system for t-PA based on the recognition of the high mannose carbohydrate structures on Asn117. To further elucidate the involvement of the mannose receptor on sinusoidal endothelial cells in the hepatic catabolism of t-PA and to identify the mechanisms involved, biochemical as well as electron microscopic studies were performed. The biochemical studies revealed that the removal of the mannose side chain in t-PA significantly reduced its clearance and degradation in isolated perfused livers. The binding of t-PA to preparations of primary hepatocytes and liver cell membranes could not be competed for by various sugars and glycoproteins, and was not dependent on the presence of carbohydrates on the molecule. This ruled out a major relevance of the sugar moieties of t-PA in its recognition by liver cells that were not of endothelial origin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Osteosynthesis equipment. Types--principles of action--radiologic evaluation].

The standard osteosynthetic implants suggested by the AO (Association for Osteosynthesis Problems) are surveyed: lag screws, tension band wires, plates, nails, external fixators, as are other bone-fixation aids with regard to function, implementation and important aspects concerning radiological evaluation.

Bone Nails↗
PubMed1991

[The radiologic evaluation of osteosyntheses].

Surgeons, orthopedic surgeons, and neurosurgeons employ a wide variety of different osteosynthetic devices in the treatment of fractures and in spinal surgery. In order to assess these instruments correctly, the radiologist should be aware of their purpose and normal appearance. The complications should be identified, such as delayed union, pseudarthrosis, dislocation, device loosening, fracture of the device, osteomyelitis, and re-fracture. To evaluate the fixation device adequately two plain radiographs are mandatory. Normal fracture healing and the most commonly used fixation devices, the abnormalities of fracture healing and their complications are discussed.

Fracture Fixation, Internal↗
PubMed1990

Intracellular transport of endocytosed proteins in rat liver endothelial cells.

1. Receptor-mediated endocytosis of mannose-terminated glycoproteins in rat liver endothelial cells has been followed by means of subcellular fractionation and by immunocytochemical labelling of ultrathin cryosections after intravenous injection of ovalbumin. For subcellular-fractionation studies the ligand was labelled with 125-tyramine-cellobiose adduct, which leads to labelled degradation products being trapped intracellularly in the organelle where the degradation takes place. 2. Isopycnic centrifugation in sucrose gradients of a whole liver homogenate showed that the ligand is sequentially associated with three organelles with increasing buoyant densities. The ligand was, 1 min after injection, recovered in a light, slowly sedimenting vesicle and subsequently (6 min) in larger endosomes. After 24 min the ligand was recovered in dense organelles, where also acid-soluble degradation products accumulated. 3. Immunocytochemical labelling of ultrathin cryosections showed that the ligand appeared rapidly after internalization in coated vesicles and subsequently in two larger types of endosomes. In the 'early' endosomes (1 min after injection) the labelling was seen closely associated with the membrane of the vesicle; after 6 min the ligand was evenly distributed in the lumen. At 24 min after injection the ligand was found in the lysosomes. 4. A bimodal distribution of endothelial cell lysosomes with different buoyant densities was revealed by centrifugation in iso-osmotic Nycodenz gradients, suggesting that two types of lysosomes are involved in the degradation of mannose-terminated glycoproteins in liver endothelial cells. Two populations of lysosomes were also revealed by sucrose-density-gradient centrifugation after injection of large amounts of yeast invertase. 5. In conclusion, ovalbumin is transferred rapidly through three endosomal compartments before delivering to the lysosomes. The degradation seems to take place in two populations of lysosomes.

Animals↗
PubMed1990

[Pneumocystis carinii pneumonia in HIV-positive and HIV-negative patients].

Bronchoalveolar lavage was used in 170 immunocompromised patients for detection of causative agents. Pneumocystis carinii was isolated 18 times from HIV-positive patients and 14 times from patients suffering from immunodeficiencies due to various other diseases. Patients with AIDS were in better clinical condition, had fewer infiltrates on chest x-ray, a higher oxygen partial pressure and lower LDH-plasma concentration than HIV-negative patients. In spite of the earlier stage of the disease patients with AIDS experience prodromal symptoms for a longer time and the number of isolated pneumocystis was larger. Mortality in AIDS patients was significantly lower than in patients with other causes of immunodeficiency.

Adult↗
PubMed1990

[Pneumonia in immunocompromised patients: the value of non-biopsy bronchoscopic examination procedures in the diagnosis of pathogens].

Bronchoscopy was performed on 101 immunocompromised patients with fever and pulmonary infiltrates. Underlying diseases were mainly hematological malignancies. In 71% of cases, etiology of pneumonia was clarified by nonbioptic bronchoscopic methods (bronchoalveolar lavage, bronchial secretions, protected specimen brush). In 51% of cases, empirical antibiotic treatment was modified following bronchoscopy. In patients with early bronchoscopy a better prognosis regarding healing and survival was observed than in those cases, where bronchoscopy was performed later during pneumonia. Bronchoalveolar lavage was particularly suited for diagnosis of Pneumocystis carinii and pneumonia due to viruses or Legionella. Sensitivity and specificity of bronchoscopy were lower for diagnosis of mycotic pneumonia and of Gram-negative or Gram-positive bacteria.

Aspergillosis↗
PubMed1990

Morphology of rat exocrine pancreas prepared by anhydrous cryo-procedures.

This paper describes and compares the morphology of a relatively complex tissue, the exocrine pancreas, prepared by state-of-the-art anhydrous cryoprocedures. Cryopreparative procedures are being used increasingly for a wide range of applications, for example, electron-probe x-ray microanalysis and immunocytochemical localization of antigenic molecules, because they preserve the composition of the specimen better than procedures involving aqueous media. Some doubts have remained concerning the morphology of cryosections and the precise identification of subcellular structures. We show that thin and sufficiently large cryosections of fresh biological tissues can be produced using commercially available hardware. The freeze-dried cryosections display high intrinsic contrast, are stable under the beam, and allow identification of intracellular fine structure.

Animals↗
PubMed1990

Hepatosplenic candidiasis, a late manifestation of Candida septicaemia in neutropenic patients with haematologic malignancies.

Systemic candidiasis with Candida-induced abscesses, predominantly in the liver and the spleen, was diagnosed in 27 patients with haematologic malignancies after intensive cytostatic therapy. Specific features included septic fever unresponsive to antimicrobial therapy, hepatosplenomegaly with multiple lesions in the liver and spleen (diameter up to 2 cm) as detected by computed tomography (CT) or ultrasound, and an elevation in liver enzymes. During treatment, induced neutropenia, hepatic and splenic foci were poorly defined histologically and were not identified by imaging procedures. After granulocyte recovery these foci showed characteristic histological patterns. Ultrasound and/or CT investigations of the abdomen now revealed characteristic lesions in the liver and the spleen. Gamma-GT and alkaline phosphatase were early indicators of hepatic involvement in Candida septicaemia and were often already elevated in aplasia.

Abscess↗
PubMed1990

Further study of the increased mortality following transurethral prostatectomy: a chart-based analysis.

Previous studies using large administrative databases found an elevated relative risk of reoperation and death after transurethral resection of the prostate compared to open prostatectomy. To investigate whether differences in case-mix unmeasured by administrative data explained this finding, we reviewed the charts of 485 patients who had undergone prostatectomy (236 open and 249 transurethral) at the Health Science Centre, Winnipeg, Manitoba, Canada between 1974 and 1980. Data from patient histories, physical examinations and laboratory evaluations were abstracted and used to control for case-mix in models comparing the rates of reoperation and mortality after transurethral versus open prostatectomy. Several models were specified. In all models the relative risk of dying after transurethral prostatectomy remained elevated (1.36 to 1.89), as did the risk for reoperation (3.62). A prospective trial is needed to establish the relative safety and effectiveness of transurethral and open prostatectomy.

Aged↗
PubMed1990

Hepatosplenic candidosis--a late manifestation of Candida septicemia.

Hepatolienal candidosis was diagnosed in 27 patients suffering from malignant hematologic disorders. All patients had received intensive cytostatic chemotherapy and developed septic, antibiotic-resistant temperatures during severe treatment-induced neutropenia. During neutropenia hepatic and splenic foci were not identified by imaging procedures. Foci were poorly defined histologically. Blastospores and pseudomycelia were seen in non-reactive tissue and within necrotic areas in the liver, spleen, and other organs. Only Candida species could be isolated. One to four weeks after granulocyte recovery, round liver and splenic foci were demonstrated by sonographic and CT scans. Histologically, there were necrotic areas with blastospores and pseudohyphae exhibiting different degrees of cellular border reaction. Whereas the maximum diameter of fungal foci in aplasia was 0.4 cm, these increased in size to 1.5 cm after granulocyte regeneration.

Adolescent↗