A critical evaluation of the binary and ternary solid-oil-water and solid-water-oil interaction.

When determining the surface energies of solids the most frequently utilised method is to measure contact angles for particular probe liquids. The measured contact angles (usually measured in air) are then combined with published values of surface- and interfacial tensions of the liquids to give the surface energy of the solid. It is, however, very seldom that sufficient attention is paid to the impurities, to the experimental (e.g. saturated vapour) conditions chosen and to the heterogeneities (chemical and structural) of the solid surface. In this study five typical probe liquids: octane, hexadecane, diiodomethane, alpha-bromonaphthalene and water have been used to establish the dispersion component of the surface energy of the solid and the hydrophobic interaction occurring at the interface of four solids: hydrophobic/hydrophilic SiO2 and hydrophobic/hydrophilic TiO2. Two (solid/liquid) and three (solid/liquid/liquid) component systems were investigated. The results are compared with previously published results when Alkenyl Succinic Anhydride (ASA) was brought into contact with SiO2 under water. The preferential surface vapour pressure and liquid spreading of the one liquid over the solids in the absence and presence of a saturated liquid vapour were evaluated as sources of errors.

Influence of film digitization on radiological interpretation.

Our objective was to evaluate the influence of changing from analogue to digital imaging on interobserver and intraobserver image interpretation. Three radiologists interpreted 96 three image series of occipitomental radiographs of paranasal sinuses from the films and from the corresponding digitized images from the screen. Images were classified according to degree of abnormality as either normal, with mucosal thickening of less than 5 mm, with mucosal thickening of 5 mm or more, total opacity, air-fluid level or polyp or cyst of maxillary sinuses. In the present study we found that there were more differences between two radiologist's interpretations with a single method than in a single radiologist's interpretations between the methods, although radiologists interpreted fewer pathological findings from the digitized images than from the corresponding films. Our data show that the results of image interpretation are preferentially dependent on the reader rather than on the method of reading.

Incidence of deep venous thrombosis after thoracotomy.

BACKGROUND: Incidence of deep venous thrombosis (DVT) after thoracotomy has not been widely studied. DVT is a frequent complication in major surgery involving abdominal and pelvic areas and lower extremities. The aim of the present study was to evaluate the rate of postoperative DVTs after surgery of the lung. METHODS: In this prospective study with 25 patients undergoing thoracotomy both legs were studied with venous duplex imaging (VDI) preoperatively and on the second postoperative day. Clinically manifest thromboembolic events during one-month postoperative period were reviewed from the patients' records. DVT prophylaxis included compression stockings and early mobilization without low-molecular weight heparin. RESULTS: Frequency of postoperative DVTs was 4%. There were no clinically manifest thromboembolic events during one-month postoperative period. In 8% of the patients an old DVT was found preoperatively. CONCLUSIONS: Based on this material, incidence of DVT is low after thoracotomy. Early mobilization and the use of compression stockings may be a sufficient form of prophylaxis in these patients. The relatively small sample size and the use of ultrasound as a screening method should be noted in judging the results.

Validity of ultrasonography in diagnosis of acute maxillary sinusitis.

BACKGROUND: Accurate diagnosis of maxillary sinusitis is difficult on the basis of clinical examination only because the signs and symptoms of sinusitis are nonspecific. A simple, rapid, and readily available method for diagnosing maxillary sinusitis in primary care would increase the accuracy of the diagnoses and thus reduce unnecessary antibiotic treatment. OBJECTIVE: To investigate the validity of ultrasonography compared with radiography and magnetic resonance imaging (MRI) in detection of maxillary sinusitis. DESIGN: Ultrasonography and plain-film radiography of the paranasal sinuses were performed on all patients and MRI was performed on 40 randomly selected patients on day 7 of the study. SETTING: Study office at the Department of Pediatrics of Turku University Hospital, Turku, Finland. PATIENTS: One hundred ninety-seven young adults who contacted the study office within 48 hours of the onset of symptoms of the common cold. MAIN OUTCOME MEASURES: Detection rates of maxillary sinusitis by ultrasonography, radiography, and MRI. RESULTS: Acute maxillary sinusitis was diagnosed in 24% of the sinuses by radiography and in 28% by MRI. Compared with MRI findings, the sensitivity of ultrasonography for detection of maxillary sinusitis was 64% (specificity, 95%). Using a 2-step diagnostic approach in which radiological findings were additionally considered in cases of negative ultrasound findings, a sensitivity of 86% (specificity, 95%) was observed. CONCLUSIONS: The high specificity of ultrasonography indicates that a positive ultrasound finding can be regarded as evidence of maxillary sinusitis. The addition of plain-film radiography in cases of negative ultrasound findings increases the diagnostic sensitivity to clinically acceptable levels without loss in specificity. Active use of ultrasonography would substantially decrease the need for radiological imaging of the sinuses and also help reduce unnecessary antibiotic treatment in primary care. Arch Otolaryngol Head Neck Surg. 2000;126:1482-1486

The occurrence of the post-thrombotic changes after an acute deep venous thrombosis. A prospective two-year follow-up study.

BACKGROUND: The aim of the study is to investigate the development of subjective and objective findings during the first two years after DVT (deep venous thrombosis). METHODS: This prospective two-year follow-up study was established in Tampere University Hospital in Finland. Twenty-six patients with a two-year follow-up after a phlebographically confirmed DVT were followed. Patients were treated conventionally with heparin and warfarin. Phlebography was repeated 7 months after DVT. Color-flow duplex imaging (CFDI) was performed in both legs 7 and 20 months after DVT. The subjective symptoms in both legs were recorded at the beginning and at the end of the follow-up. The development of venous reflux, obstruction and subjective symptoms after DVT were studied. RESULTS: 50% of the legs with DVT had a pathological (deep reflux or obstructive change) CFDI-finding in the popliteal segment after a 20-month follow-up. The pathological findings in the control legs were rare. The rate of recanalisation was high. There was no difference between calf and more proximal DVTs. Pain (62%), oedema (46%) and pigmentation (35%) were common and only 27% of the legs with DVT were asymptomatic. CONCLUSIONS: The development of the post-thrombotic syndrome begins quite early. The frequency of the subjective symptoms is high. Calf DVT may lead to postthrombotic sequelae in the popliteal segment.

Imaging end-stage kidney disease in adults. Low-field MR imaging with magnetization transfer vs. ultrasonography.

PURPOSE: To 1) assess the potential of magnetization transfer (MT)-weighted MR imaging to improve the often poor visibility of native kidneys in patients with a renal transplant; and 2) compare low-field MR imaging and ultrasonography (US) for imaging these fibrotic kidney remnants. MATERIAL AND METHODS: Seventy-two native kidneys of 36 patients were prospectively evaluated with US and MR. In low-field (0.1 T) MR imaging, T1-, T2- and MT-weighted sequences were used. MT-weighted images were compared with T2-weighted images in their ability to delineate the kidneys from their surroundings whereas US and MR were compared for detection of renal cysts and possible solid tumors. RESULTS: MT-weighted images proved superior to conventional T2-weighted images in producing contrast between the kidney remnants and their fatty surroundings. Although US revealed a few small renal cysts that were not seen at MR images, no statistical difference was found between the two modalities in this respect. CONCLUSION: MT imaging, due to its unique protein-specific signal depression, offers significantly improved visualization and delineation of end-stage kidneys. US, because its better availability and cost-benefit ratio, remains the method-of-choice compared to low-field MR imaging in detecting cysts in multicystic kidneys. MR investigation is helpful in selected patients and may be used as an alternative.

Site-specific mutations in the D1 polypeptide affect the susceptibility of Synechocystis 6803 cells to photoinhibition.

Photoinhibition of photosystem II in the cyanobacterium Synechocystis 6803 was followed after site-specific mutagenesis of the D1 polypeptide. Mutations were created in the stromal/cytosolic loop connecting helices D and E. Two mutations E243K and CA1, a deletion of the three glutamates 242-244 and a substitution Q241H, were made in the putative cleavage area of the D1 polypeptide. A third mutation E229D was made in the PEST-like sequence. Mutants and control cells were illuminated and FV/FM was recorded. Compared to the control, the mutants were less photoinhibited. Fluorescence relaxation after a single flash was delayed in CA1. Restoration of FV/FM after photoinhibition in the mutants was totally dependent on protein synthesis while control cells were able to recover partially also when protein synthesis was inhibited. In addition, the protein synthesis-dependent recovery of CA1 was slowed down. Our results indicate a correlation between the mutated amino acids and photoinhibition of photosystem II.

Accumulation of pyrophosphate correlates with the increased level of nucleoside triphosphates in Escherichia coli.

We measured the concentration of nucleoside triphosphates and inorganic pyrophosphate in Escherichia coli in conditions where nucleotide synthesis or nucleic acid synthesis was inhibited. The inhibitors that brought about an accumulation of some of the four ribonucleoside triphosphates also increased the pyrophosphate level. In a pyrimidine auxotrophic strain uracil starvation led to simultaneous accumulation of ATP and pyrophosphate, and they both rapidly returned to normal level when starvation was relieved. These results indicate the possible involvement of pyrophosphate in the reactions leading to the accumulation of nucleoside triphosphates.

A method for concentration of nucleoside triphosphates by coprecipitation with calcium fluoride.

A method for concentration of nucleoside triphosphates (NTP) is described. NTPs are quantitatively coprecipitated from the solution with calcium fluoride. The precipitate is separated by filtration through a membrane filter and NTPs are dissolved from the filter by immersing it in 0.5 N H2SO4. With this method also nucleoside diphosphates can be efficiently concentrated, but the method does not work with nucleoside monophosphates or cyclic AMP.