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PubMedDate not supplied

A comparison of diagnostic tests to determine Helicobacter pylori infection.

Twenty-five Helicobacter pylori positive and 25 H. pylori negative subjects as defined by culture and phase contrast microscopy of antral biopsy specimens obtained from routine upper endoscopy were studied. Antral biopsies were examined by rapid urease test, phase contrast microscopy, culture and histology. Venous blood was tested for H. pylori specific IgG antibodies by an ELISA technique. Within 7 days of endoscopy the patients also had a [14C]-urea breath test. The sensitivity and specificity of the rapid urease test was 92%, the breath test 96% and 100%, histopathology 96% and 91% and serology 96% and 88%, respectively. The [14C]-urea breath test performed over 1 h with sampling of subjects at 0, 0.5 and 1 h was an accurate and reliable method. Results expressed as counts per minute of the expired 14CO2 proved to be a simple method of assessing H. pylori status. A significant correlation between severity of histological antral gastritis and the amount of 14CO2 expired was observed. This study has shown that the non-invasive 14C-urea breath test and serology are highly sensitive and specific for the diagnosis of H. pylori infection.

Breath Tests↗
PubMed2003

Asbestos release during removal of resilient floor covering materials by recommended work practices of the resilient floor covering institute.

The release of asbestos during maintenance and removal of resilient floor covering is of concern to health professionals and many regulators. This study assesses the asbestos levels observed during removal of resilient floor covering products using the "Recommended Work Practices" (1995) of the Resilient Floor Covering Institute or other methods requiring containment (Controls). The 1995 "work practices" require wet removal or dry heat removal but do not require the use of respirators. Wet removals of sheet vinyl/separated backing, 12" x 12" vinyl asbestos tile/mastic, and 9" x 9" asphalt tiles/mastic were conducted and the air was sampled during each procedure. Settled dust samples were collected at the sites of RFCI square tile removal and pieces of each type of tile were broken in a mini-enclosure to evaluate asbestos emissions. Analyses of the air samples collected during the removals showed that the RFCI methods did not produce asbestos counts significantly different from the Control methods requiring containment. Only a small number (0.7%) of fibers and structures, counted and measured by Analytical Transmission Electron Microscopy, would have been counted using the rules for Phase Contrast Microscopy in the 7400 method specified by Occupational Safety and Health Administration regulations. This indicates workers in similar situations without respirators are likely to have unknown exposure levels. A high percentage of these fibers and structures are 5 micrometers or less in length, smaller than 0.5 micrometer in diameter, and are easily inhaled. The RFCI air sample and settled dust data may cause regulators to consider requiring respiratory protection, cleanup procedures, and methods to control asbestos migration. Other areas that might be addressed are clearance levels and their measurement, removal area size, bulk sample analysis by transmission electron microscopy if polarized light microscopy reports less than 1 percent asbestos, better worker exposure evaluation, and supervisor/worker training in accordance with the Model Accreditation Plan.

Air Pollutants, Occupational↗
PubMed1994

Fibrogenic effect of wollastonite compared with asbestos dust and dusts containing quartz.

The distribution of length and diameter and the aspect ratio of crocidolite asbestos, a mineral substitute for asbestos (wollastonite), a manmade mineral fibre (glass wool), and synthetic fibres (polypropylene and polyacrylonitrite) were determined by light microscopy with phase contrast and, for crocidolite, also with transmission electron microscopy. The synthetic organic fibres and manmade mineral fibre used were of a size exceeding that considered respirable. Respirable materials were given to rats by the intratracheal method and after exposure for a standard time interval the main indices of fibrogenic effects--the total hydroxyproline content, the wet weight of the lung, and the total lipid content in the lung--were estimated. For wollastonite there was a significant increase in these variables in comparison with the controls. The fibrogenicity was considerably less than that of crocidolite and quartz.

Animals↗
PubMed1989

Comparison of different assays for the aggregation of oral bacteria by human whole saliva.

For comparison, human whole saliva-induced aggregation was studied by phase-contrast microscopy, spectrophotometry combined with macroscopic observations, and in microtiterplate assay under identical experimental conditions for Actinomyces viscosus HG 85 (T14-V) and HG 380 (T14-AV), Bacteroides gingivalis HG 66 (W 83), Streptococcus rattus HG 59 (BHT), and Streptococcus sanguis I HG 169. The entire process of formation, extension, and sedimentation of aggregates could merely be observed by the combination of these assays. The very first stages of aggregation could only be detected and quantitated by phase-contrast microscopy. Within 2 1/2 min, 50% of the A. viscosus, S. rattus, and S. sanguis cells were aggregated, denoted as T50. In microtiterplates, however, aggregates were observed in general only after sedimentation at 30-45 min of incubation, expressed as TA. For interpretation of the spectrophotometric curves, additional microscopic and macroscopic data were a prerequisite. The small decline in absorbance during the first 30-45 min (phase 1) corresponded to the formation and extension of nonsedimenting aggregates, whereas the subsequent pronounced fall in absorbance (phase 2) was caused by the massive sedimentation of aggregates. The moment of inflexion between both phases, TI, marked the onset of sedimentation of aggregates and corresponded very well with TA, at which time already 92-98% of the cells were aggregated as quantitated by microscopy. In conclusion, only by microscopy the formation and extension of aggregates could be observed within a few minutes and quantitated in terms of aggregation rate. From 30-45 min, merely the sedimentation of aggregates was visualized in microtiterplates, whereas the time course of the overall process was recorded indirectly by spectrophotometry.

Actinomyces↗
PubMed1993

Isolation, culture, and characterization of human pancreatic duct cells.

To establish a suitable control for pancreatic tumor cell lines, we have isolated and cultured primary human pancreatic duct cells from transplant donors. Duct cells were isolated by dissecting the main pancreatic duct and first-degree branches and enzymatic digestion. Aggregates of cells were cultured for 1 up to 5 weeks and monitored for changes in morphology and growth by phase contrast microscopy. Contaminating fibroblasts were mechanically removed from day 4 on and by cloning of epithelial cells. Cultured cells were characterized by phase contrast microscopy, electron microscopy, and immunofluorescence with antibodies against intermediate filaments (cytokeratins, vimentin, desmin), mucins (Du-Pan-2, CA 19-9), carbonic anhydrase II, acinar cell enzymes (amylase, lipase, trypsin), and islet cells. About 90% of the cultured cells could be identified as ductal epithelial cells by their expression of cytokeratins, mucins, and carbonic anhydrase II. These cells showed the ultrastructural features of duct cells. After 3-5 weeks of culture, most of the cultured cells showed co-expression of cytokeratins and vimentin in addition to duct cell markers. About 10% of cells were contaminating fibroblasts (vimentin positive, cytokeratin negative). The cultured normal human duct cells as the postulated cells of origin of the pancreatic adenocarcinoma may serve as a useful control for cultured pancreatic tumor cell lines.

Cell Separation↗
PubMed2006

Assessment of airborne asbestos exposure during the servicing and handling of automobile asbestos-containing gaskets.

Five test sessions were conducted to assess asbestos exposure during the removal or installation of asbestos-containing gaskets on vehicles. All testing took place within an operative automotive repair facility involving passenger cars and a pickup truck ranging in vintage from late 1960s through 1970s. A professional mechanic performed all shop work including engine disassembly and reassembly, gasket manipulation and parts cleaning. Bulk sample analysis of removed gaskets through polarized light microscopy (PLM) revealed asbestos fiber concentrations ranging between 0 and 75%. Personal and area air samples were collected and analyzed using National Institute of Occupational Safety Health (NIOSH) methods 7400 [phase contrast microscopy (PCM)] and 7402 [transmission electron microscopy (TEM)]. Among all air samples collected, approximately 21% (n = 11) contained chrysotile fibers. The mean PCM and phase contrast microscopy equivalent (PCME) 8-h time weighted average (TWA) concentrations for these samples were 0.0031 fibers/cubic centimeters (f/cc) and 0.0017 f/cc, respectively. Based on these findings, automobile mechanics who worked with asbestos-containing gaskets may have been exposed to concentrations of airborne asbestos concentrations approximately 100 times lower than the current Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 0.1 f/cc.

Air Pollutants, Occupational↗
PubMed2000

Rotational-diversity phase estimation from differential-interference-contrast microscopy images.

An iterative phase-estimation method for the calculation of a specimen's phase function or optical-path-length (OPL) distribution from differential-interference-contrast (DIC) microscopy images is presented. The method minimizes the least-squares discrepancy measure by use of the conjugate-gradient technique to estimate the phase function from multiple DIC images acquired at different specimen rotations. The estimate is regularized with a quadratic smoothness penalty. Results from testing the method with simulations and measured DIC images show improvement in the estimated phase when at least two rotationally diverse DIC images instead of a single DIC image are used for the estimation. The OPL of a cell that is estimated from two DIC images was found to be much more reliable than the OPL computed from single DIC images (which had a coefficient of variation equal to 15.8%).

Computer Simulation↗
PubMed1957

Phase contrast and interferometric microscopy of the L. E. cell phenomenon.

Alterations in the cellular morphology of polymorphonuclear leukocytes and lymphocytes under the influence of serum from patients having disseminated lupus erythematosus were observed under the phase contrast microscope. These changes appear to involve the cell nucleus without significant visible incorporation of cytoplasm. In the formation of the L.E. body, there is a loss of internal nuclear structure and a subsequent nuclear swelling and extrusion of the nuclear contents from the cell to form the free L.E. body. The possible incorporation of cytoplasmic substance cannot alone account for the large mass of the L.E. body as contrasted with the parent nucleus or nuclear lobe. Measurements of dry mass by means of the interference microscope show a two and one-half-fold increment in dry mass in L.E. bodies compared to parent lymphocyte nuclei. This confirms previous cytochemical studies, and establishes that an influx of protein into the leukocyte nucleus is an integral part of the L.E. phenomenon. That the accumulation of extraneous protein within the L.E. body is simultaneous with or subsequent to a disruption of the normal structure of the leukocyte nucleus is apparent from these studies, but the pathogenesis of this alteration is as yet unknown.

Cell Nucleus↗
PubMed1982

Effect of epidermal growth factor on membrane motility and cell locomotion in cultures of human clonal glioma cells.

Two clones, designated Cl 2 and Cl 3, were established from the human malignant glioma line U-343 MGa. The astrocytic origin of the cells was proven by the presence in virtually 100% of the cells of the astrocyte marker glial fibrillary acidic protein. The addition of 10 ng epidermal growth factor (EGF) per milliliter to Cl 2 and Cl 3 cells resulted in the rapid appearance of large cell surface ruffles, visualized by scanning electron microscopy. A time course study by phase contrast microscopy showed that the maximal ruffling activity occurred 5 minutes after addition of EGF. Under basic culture conditions (Eagle's MEM, 10% fetal calf serum), Cl 2 and Cl 3 cells were essentially immobile and formed tightly packed, well demarcated colonies. In the presence of 10 ng EGF per milliliter, no defined colonies were formed and the cells seemed to move around freely. The stimulatory effect of EGF on cell migration was confirmed by growing the cells on a deposit of colloidal gold; in the absence of EGF, the cells remained immobile whereas cells grown at 10 ng EGF per ml formed long phagokinetic tracks. The effect of EGF on membrane motility and cell locomotion occurred in the absence of any effect of EGF on growth rate; both clones multiplied at the same rate in the absence as in the presence of EGF. Binding experiments using 125I-labeled EGF demonstrated a single class of high affinity receptors. The number of 180,000 receptors per cell was estimated in both clones. The finding that human glioma cells in culture require EGF for their migration raises the interesting possibility that tumor cells in vivo may respond in a similar fashion, and in that case require a growth factor for migration and for the expression of their infiltrative growth potential. Furthermore, the present findings strengthen the notion that glial cells should be recognized as targets for EGF.

Cell Division↗
PubMed2006

An efficient way of high-contrast, quasi-3D cellular imaging: off-axis illumination.

An imaging system enabling a convenient visualisation of cells and other small objects is presented. It represents an adaptation of the optical microscope condenser, accommodating a built-in edge (relief) diaphragm brought close to the condenser iris diaphragm and enabling high-contrast pseudo-relief (quasi-3D) imaging. The device broadens the family of available apparatus based on the off-axis (or anaxial, asymmetric, inclined, oblique, schlieren-type, sideband) illumination. The simplicity of the design makes the condenser a user-friendly, dedicated device delivering high-contrast quasi-3D images of phase objects. Those are nearly invisible under the ordinary (axial) illumination. The phase contrast microscopy commonly used in visualisation of phase objects does not deliver the quasi-3D effect and introduces a disturbing 'halo' effect around the edges. The performance of the device presented here is demonstrated on living cells and tissue replicas. High-contrast quasi-3D images of cell-free preparations of biological origin (paper fibres and microcrystals) are shown as well.

Animals↗
PubMed1999

A risk assessment for exposure to grunerite asbestos (amosite) in an iron ore mine.

The potential for health risks to humans exposed to the asbestos minerals continues to be a public health concern. Although the production and use of the commercial amphibole asbestos minerals-grunerite (amosite) and riebeckite (crocidolite)-have been almost completely eliminated from world commerce, special opportunities for potentially significant exposures remain. Commercially viable deposits of grunerite asbestos are very rare, but it can occur as a gangue mineral in a limited part of a mine otherwise thought asbestos-free. This report describes such a situation, in which a very localized seam of grunerite asbestos was identified in an iron ore mine. The geological occurrence of the seam in the ore body is described, as well as the mineralogical character of the grunerite asbestos. The most relevant epidemiological studies of workers exposed to grunerite asbestos are used to gauge the hazards associated with the inhalation of this fibrous mineral. Both analytical transmission electron microscopy and phase-contrast optical microscopy were used to quantify the fibers present in the air during mining in the area with outcroppings of grunerite asbestos. Analytical transmission electron microscopy and continuous-scan x-ray diffraction were used to determine the type of asbestos fiber present. Knowing the level of the miner's exposures, we carried out a risk assessment by using a model developed for the Environmental Protection Agency.

Asbestos, Amosite↗
PubMed1985

Effect on growth curve patterns of brief exposure of bacteria to different concentrations of beta-lactam antibiotics.

The effect of a brief beta-lactam action on a bacterial culture has been studied by combining the use of a high performance photometer with phase contrast microscopic examination. After exposure of the culture with the antibiotic, the growth curves presented in logn OD have shown the importance of the pre-lytic increase in OD (PIOD). Using Escherichia coli a study of the PIOD values allowed us to separate the beta-lactam antibiotics studied into two groups: those whose PIOD were concentration-dependent (ampicillin, carbenicillin, ticarcillin, moxalactam, ceftazidime, cefsulodin, cefotaxime) and those whose PIOD were concentration-independent (or weakly dependent) (azlocillin, mezlocillin, piperacillin). When the PIOD was independent of the concentrations, long filaments were observed by phase contrast microscopy. Using Pseudomonas aeruginosa, all the antibiotics studied produced PIOD values that were barely dependent of the concentrations, and long filaments were observed by phase contrast microscopy. Study of the lag of regrowth in the post antibiotic period using a beta-lactamase technique showed that, if the PIOD was hardly concentration dependent, so was the lag of regrowth.

Ampicillin↗
PubMed1996

In vitro, follicle-stimulating hormone prevents apoptosis and stimulates deoxyribonucleic acid synthesis in the rat seminiferous epithelium in a stage-specific fashion.

The effects of FSH on stage-specific apoptosis and DNA synthesis in the adult rat seminiferous epithelium were studied in vitro. Seminiferous tubular segments from stages I, V, VIIa, and VIII-IX were cultured for 24, 48, and 72 h in different concentrations of FSH. Apoptotic cells were detected by in situ end labeling of DNA strands and quantified from squash preparations. After 48 h of culture, a FSH concentration of 2 ng/ml prevented apoptosis of early (steps 1-3) spermatids. In stage VIII-IX tubules cultured for 72 h, FSH decreased the apoptosis of pachytene spermatocytes. An apoptotic type of cell death of germ cells was confirmed by DNA laddering, electron microscopy, supravital acridine orange staining, and phase contrast microscopy of unstained living cells. The effects of FSH on stage-specific DNA synthesis were studied using the same culture system. FSH increased [3H]thymidine incorporation specifically at stages I and VIII-IX, and autoradiography confirmed stimulation of mitotic and meiotic DNA synthesis in type B spermatogonia and preleptotene spermatocytes, respectively. Increased thymidine incorporation also suggested that FSH stimulated DNA synthesis of type A and intermediate spermatogonia. Most effects exerted by FSH were seen in stages containing high levels of FSH receptors and FSH-stimulated cAMP production. In conclusion, the results suggest that FSH, probably acting via Sertoli cells, has a regulatory function in spermatogenic apoptosis and DNA synthesis in stages previously demonstrated to be preferentially dependent on FSH stimulation.

Acridine Orange↗
PubMed1979

Pairing of spermatozoa in the epididymis of the opossum (Didelphis virginiana): a scanning electron microscopic study.

Spermatozoa of the opossum, Didelphis virginiana, were taken from three different regions of the epididymis and examined by scanning electron microscopy, phase-contrast and dark-field microscopy. It has been demonstrated that marked morphological changes occur in spermatozoa during their passage through the epididymis. In the first segment or head of the epididymis, spermatozoa are non-motile and the long axis of their nuclei is perpendicular to that of the tail. The nucleus is V-shaped with a thick and a thin arm. At the junction of the two arms. At the junction of the two arms, where the arms join, the articular fossa receives the capitulum of the connecting piece which attaches the head of the spermatozoon to the tail. Spermatozoa from the central region of the epididymis show a re-orientation of the nuclei which now lie parallel to the long axis of the tail. Both paired and unpaired spermatozoa are found and show an increase in motility. In the caudal region of the epididymis all spermatozoa are paired. Pairing occurs as a result of the close apposition of adjacent cell membranes covering the acrosomes of the larger arms.

Animals↗