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Results for “Morphological Characterization”

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PubMed1979

Bactericidal activity of the tail of Pseudomonas aeruginosa bacteriophage PS17.

The tail of bacteriophage PS17 of Pseudomonas aeruginosa was shown to be bactericidal, and its properties were compared with those of pyocin R1. Temperature-sensitive mutants were isolated from PS17, and the products at nonpermissive temperature were morphologically characterized. Bactericidal substances were found in the lysates of such mutants that were defective in the head formation but not in the tail formation. Phage tails were purified from the lysate of one such mutant, and its chemical and biological properties were studied. Isolated tails killed sensitive cells by a single-hit process and repressed the uptake of leucine in sensitive cells. These results were consistent with the previous findings on the serological and morphological relationship between PS17 and pyocin R1. However, certain differences were also shown between them in shape and protein composition.

Antigens, Viral↗

PubMed1995

Dexamethasone-induced ocular hypertension in perfusion-cultured human eyes.

PURPOSE: Glucocorticoid administration can lead to the development of ocular hypertension and corticosteroid glaucoma in a subset of the population through a decrease in the aqueous humor outflow facility. The purpose of this study was to determine whether glucocorticoid treatment can directly affect the outflow facility of isolated, perfusion-cultured human eyes. METHODS: The anterior segments of human donor eyes from regional eye banks were placed in a constant flow, variable pressure perfusion culture system. Paired eyes were perfused in serum-free media with or without 10(-7) M dexamethasone for 12 days. Intraocular pressure was monitored daily. After incubation, the eyes were morphologically characterized by light microscopy, transmission and scanning electron microscopy, and scanning laser confocal microscopy. RESULTS: A significant increase in intraocular pressure developed in 13 of the 44 pairs of eyes perfused with dexamethasone with an average pressure rise of 17.5 +/- 3.8 mm Hg after 12 days of dexamethasone exposure. The contralateral control eyes, which did not receive dexamethasone, maintained a stable intraocular pressure during the same period. The outflow pathway of the untreated eyes appeared morphologically normal. In contrast, the dexamethasone-treated hypertensive eyes had thickened trabecular beams, decreased intertrabecular spaces, thickened juxtacanalicular tissue, activated trabecular meshwork cells, and increased amounts of amorphogranular extracellular material, especially in the juxtacanalicular tissue and beneath the endothelial lining of the canal of Schlemm. The dexamethasone-treated nonresponder eyes appeared to be morphologically similar to the untreated eyes, although several subtle dexamethasone-induced morphologic changes were evident. CONCLUSION: Dexamethasone treatment of isolated, perfusion-cultured human eyes led to the generation of ocular hypertension in approximately 30% of the dexamethasone-treated eyes. Steroid treatment resulted in morphologic changes in the trabecular meshwork similar to those reported for corticosteroid glaucoma and open angle glaucoma. This system may provide an acute model in which to study the pathogenic mechanisms involved in steroid glaucoma and primary open angle glaucoma.

Aged↗

PubMed1994

Interclonal heterogeneity in a human epithelioid-sarcoma cell line (GRU-1).

Three clonal sub-populations, GRU-IA, GRU-IB, and GRU-IC, isolated from the human epithelioid sarcoma cell line GRU-I, were characterized morphologically, cytogenetically and with regard to proliferation kinetics. Immunocytochemically, major differences became evident in the expression of cytokeratin 18 and neurofilament proteins, which are indicative for epithelial and neural differentiation respectively. Vimentin, a mesenchymal differentiation marker, however, could be detected in all tumor cells of each sub-population. Laminin, a major compound of basement membranes, formed abundant intercellular network-like patterns in GRU-IB and GRU-IC, whereas GRU-IA was characterized by a diffuse intracellular reaction, suggesting a disorder in laminin secretion. Cytogenetically, all sub-populations proved to be DNA-aneuploid, the DNA index ranging from 1.4 to 1.5. Proliferation analysis revealed doubling times ranging from 13 (GRU-IC) to 19 hr (GRU-IA). These strictly defined clonal sub-populations provide a valuable tool for further investigations of the biological behavior of human epithelioid sarcoma with special regard to tumor heterogeneity.

Aneuploidy↗

PubMed2003

PA-457: a potent HIV inhibitor that disrupts core condensation by targeting a late step in Gag processing.

New HIV therapies are urgently needed to address the growing problem of drug resistance. In this article, we characterize the anti-HIV drug candidate 3-O-(3',3'-dimethylsuccinyl) betulinic acid (PA-457). We show that PA-457 potently inhibits replication of both WT and drug-resistant HIV-1 isolates and demonstrate that the compound acts by disrupting a late step in Gag processing involving conversion of the capsid precursor (p25) to mature capsid protein (p24). We find that virions from PA-457-treated cultures are noninfectious and exhibit an aberrant particle morphology characterized by a spherical, acentric core and a crescent-shaped, electron-dense shell lying just inside the viral membrane. To identify the determinants of compound activity we selected for PA-457-resistant virus in vitro. Consistent with the effect on Gag processing, we found that mutations conferring resistance to PA-457 map to the p25 to p24 cleavage site. PA-457 represents a unique class of anti-HIV compounds termed maturation inhibitors that exploit a previously unidentified viral target, providing additional opportunities for HIV drug discovery.

Anti-HIV Agents↗

PubMed2005

Classification and pathology of pituitary tumors.

Pituitary adenomas originating in adenohypophysial cells represent the most common neoplasms of the sella turcica. The pathologist's goal is the optimal diagnosis and classification of pituitary adenomas. Lack of clinicopathological correlations in the past classification of pituitary adenomas, which was based on the tinctorial properties of adenoma cells, limited the importance of histological diagnosis. Morphologic separation of pituitary cells by electron microscopy provided fundamental knowledge to classify pituitary adenomas. Immunohistochemistry represents the gold standard of the current classification. Combined morphologic and immunohistochemical diagnostic approaches resulted in the clinicopathologic classification of pituitary adenomas. The WHO classification of 2004 is based on morphologic features and takes into consideration findings from imaging procedures and clinical symptoms. Morphologic characterization of pituitary tumors and correlation of the hormone product with hormone secretion provides the clinician with useful information. In addition, the utility of tumor markers offers objective information in managing the patient and predicting responses to specific treatment. The Ki-67 labeling index (LI) is widely used for it correlates with invasiveness and probably prognosis. Adenomas showing increased ( >3%) LI and extensive p53 immunoreactivity should be termed "atypical adenomas" suggesting aggressive potential or malignant transformation. Morphologic separation of adenoma from carcinoma is not feasible. The term pituitary carcinoma should be exclusively applied when cerebrospinal and/or systemic metastases are definite.

Adenoma↗

PubMed1998

Morphology of chemically crosslinked ultrahigh molecular weight polyethylene.

Morphological characterization of chemically crosslinked ultrahigh molecular weight polyethylene was performed by differential scanning calorimetry and scanning electron microscopy. The lamellar thickness of nascent UHMWPE inferred from DSC endotherms showed a very broad distribution, which was reduced significantly after melting and recrystallizing in DSC. Peroxide crosslinking further reduced the lamellar thickness distribution compared to uncrosslinked samples. After gamma-irradiation, a slowly cooled peroxide-free sample showed a greater increase in lamellar thickness distribution. Examination of the morphology of freeze-fractured surfaces by SEM showed that a slowly cooled peroxide-free UHMWPE exhibited a rougher fracture while chemically crosslinked samples showed a smoother fracture. After compression molding at 300 degrees C for 2 h, the grain boundaries between particles disappeared for all UHMWPE samples, indicating a complete fusion of the original flakes.

Calorimetry, Differential Scanning↗

PubMed1999

Intracellular filling and reconstruction of identified neurons in fixed rat brain slices.

A simple technique for the morphological characterization of pre-labelled neurons in fixed brain slices is described. Neurons are retrogradely-labeled with a carbocyanine dye and the tissue is fixed and sliced. Individual labeled cells from the interior of a slice are then visualized on an upright fluorescence microscope and impaled with a micropipet containing rhodamine or fluorescein-peroxidase conjugates. The cells are filled by iontophoresis, postfixed, and the peroxidase is oxidized into a permanent, opaque reaction product. The dendritic morphology of the neurons is then reconstructed under camera lucida and quantified.

3,3'-Diaminobenzidine↗

PubMed2006

Pathology and genetics of multiple system atrophy: an approach to determining genetic susceptibility spectrum.

Recent advances in the molecular pathology and genetics of multiple system atrophy (MSA) indicate that the disease involves plural pathogenic mechanisms. The determination of the morphological spectrum of MSA using quantitative pathological analysis points to the need for further investigation to determine the population-bound phenotype distribution of MSA. These notions support the hypothesis that a spectrum of genetic susceptibility factors underlies MSA pathogenesis. A possibly effective strategy for determining this genetic susceptibility spectrum is to perform an association study of important genes for neurodegenerative diseases, which are prevalent in a population, using linkage disequilibrium mapping in MSA patients with well-characterized morphological phenotypes.

Genetic Predisposition to Disease↗

PubMed2000

[Effect of rhTFAR19 protein on cell cycle and apoptosis of MCF-7 induced by gamma-ray].

OBJECTIVE: To investigate the effect of protein product of TFAR19, an apoptosis-related gene previously cloned from leukemia cell line TF-1 cultured in medium deprived of growth factor, on cell cycle and apoptosis of human breast cancer induced by gamma-ray. METHODS: Cell morphology, fluorescence microscopy, laser scanning confocal microscopy, single-cell gel electrophoresis (SCGE) and flow cytometry (FCM) were applied to study cell cycle and apoptosis of breast cancer cell line MCF-7. RESULTS: rhTFAR19 protein itself had no effect on cell cycle arrest and apoptosis of MCF-7 cell induced by gamma-ray. When MCF-7 cells were pretreated with 10 micrograms/ml rhTFAR19 and then irradiated with 12 Gy gamma-ray, cell apoptosis was observed. It was characterized morphologically by chromatin condensation, nucleoar disintegration, formation of apoptotic bodies, and typical "cornet" on SCGE. CONCLUSION: TFAR19 protein has no apparent effect on MCF-7 cell cycle induced by gamma-ray. However, it synergizes with gamma-radiation in the induction and enhancement of apoptosis.

Apoptosis↗

PubMed2001

Effects of beta-aminopropionitrile on equine tendon metabolism in vitro and on effects of insulin-like growth factor-I on matrix production by equine tenocytes.

OBJECTIVE: To investigate effects of beta-aminopropionitrile and a combination of insulin-like growth factor (IGF)-I and beta-aminopropionitrile on metabolism of equine tendon fibroblasts. SAMPLE POPULATION: Flexor tendon explants from 3 horses. PROCEDURE: Explants received 1 of 4 treatments (control, IGF-I, beta-aminopropionitrile, and IGF-I/beta-aminopropionitrile) for 10 days, and message expression for collagen types I and III was assessed by use of in situ hybridization. Histologic findings, new protein production, and quantitative determinations of glycosaminoglycan, DNA, and de novo collagen synthesis were made. RESULTS: Insulin-like growth factor-I stimulated an anabolic response in tendon. Collagen synthesis and glycosaminoglycan and DNA content of explants were all increased. Beta-aminopropionitrile significantly suppressed collagen synthesis, which was not ameliorated by concurrent IGF-I treatment. Beta-aminopropionitrile caused alterations in cell morphology characterized by large round cells with eccentric nuclei and decreased density of collagen fibers. Protein production and collagen type-III mRNA expression were reduced in these cells. CONCLUSIONS AND CLINICAL RELEVANCE: Treatment with beta-aminopropionitrile resulted in decreased production of protein and collagen synthesis, which could be expected to suppress tendon healing. The negative effects of beta-aminopropionitrile could not be abrogated by addition of IGF-I to the medium. Treatment resulted in alterations in cell morphology and matrix consistency, which could further delay tendon healing. Beta-aminopropionitrile may impair tendon healing at a cellular level by decreasing collagen production or increasing rate of degradation of existing matrix. Because of reduced crosslinking during beta-aminopropionitrile treatment, in combination with transiently decreased tensile strength, alterations in collagen content and structure may weaken the healing tendon.

Aminopropionitrile↗

PubMed2026

Clinical and Genomic Insights into the Allodiploid Hybrid Pathogen Aspergillus latus: A Retrospective Case Series.

Aspergillus latus is an emerging cryptic allodiploid hybrid pathogen within Aspergillus section Nidulantes that closely resembles related species and therefore prone to misidentification by routine diagnostic methods. Therefore, its true clinical burden is likely underestimated. In this study, we retrospectively characterized five patients with A. latus infections identified by metagenomic next-generation sequencing (mNGS) at a tertiary hospital in China. Clinical manifestations varied according to host immune status, ranging from a subclinical pulmonary lesion in an immunocompetent individual to aggressive disease in highly immunocompromised patients. Conventional microbiological methods showed limited sensitivity and consistently misidentified the isolates as A. nidulans, whereas mNGS enabled accurate detection of A. latus together with complex co-infections. Three viable clinical isolates were recovered for morphological characterization, antifungal susceptibility testing, and whole-genome sequencing (WGS). All tested isolates demonstrated reduced susceptibility to echinocandins but remained susceptible to mold-active triazoles and amphotericin B. Furthermore, WGS and macrosynteny analyses confirmed their allodiploid hybrid nature, revealing a mosaic genome derived from A. spinulosporus and an A. quadrilineatus-related lineage. Collectively, these findings highlight that A. latus may be missed by routine diagnostic methods and may exhibit a distinct antifungal susceptibility profile. Molecular approaches such as mNGS and WGS may therefore help achieve accurate species-level identification and support targeted antifungal therapy. Given this small retrospective case series, larger prospective and multicenter studies are needed to validate these observations and better define the epidemiology, clinical spectrum, and therapeutic implications of this emerging allodiploid hybrid pathogen.

Retrospective Studies↗

PubMed1991

[First results with a microbiological quick diagnostic procedure in periodontitis].

We tested a new diagnostic procedure for the characterization of subgingival plaque in 119 subjects suffering from adult periodontitis. The method can be characterized as a hydrolysis of BANA (N-benzoyl-DL-arginine-beta-naphthylamide) by peptidases of Porphyromonas gingivalis, Bacteroides forsythus and Treponema denticola. The result of a positive will be a more or less blue coloured test paper representing the amount of these three peridontal pathogens into the subgingival plaque. After the periodontal initial therapy the frequency of the positive colour reaction was significantly reduced. A correlation between the colour reaction and the clinical signs of periodontitis as well as the morphological characterization of subgingival plaque by darkfield microscopy could not been found. The new method for the characterization subgingival plaque seems to be useful for the judgement of a successful periodontal therapy at single sites.

Bacteroides↗

PubMed1998

Primary malignant melanoma with rhabdoid features: a histologic and immunocytochemical study of three cases.

Malignant rhabdoid tumors are morphologically characterized by the presence of sheets of large polygonal cells with abundant cytoplasm containing eosinophilic inclusions. They have vesicular nuclei, often with prominent central nucleoli. The term rhabdoid tumor was originally coined to describe a group of rare, aggressive renal neoplasms of childhood. Since then, similar lesions, so-called extrarenal malignant rhabdoid tumors have been increasingly reported. The evidence to date suggests that, at least in extrarenal locations, rhabdoid tumors do not constitute a homogeneous entity, but rather represent the shared morphological pattern of a diverse range of malignant neoplasms. Although such rhabdoid features are not uncommon in metastatic malignant melanoma, they have only once been briefly described in a primary lesion. We report three further cases of cutaneous primary malignant melanoma with rhabdoid morphology.

Adult↗

PubMed1996

Regional heterogeneity in the response of astrocytes following traumatic brain injury in the adult rat.

The regional distribution and temporal appearance of astrocytes expressing glial fibrillary acidic protein (GFAP), S100 protein, and vimentin were determined in a nonpenetrating lateral fluid percussion (LFP) brain injury model. Following injury, reactive astrocytes were observed in the subcortical white matter tracts as early as 1 day, in the hippocampus and injured cortex by 3 days, and in the thalamus by 1 week. Reactive astrocytes in the injured cortex, subcortical white matter tracts, and CA3 region of the hippocampus were all vimentin positive at 1 month post-injury. These astrocytes had a distinct morphology characterized by an enlarged cell body and long intertwined processes. In contrast, reactive astrocytes in the thalamic nuclei never expressed vimentin, and displayed an enlarged cell body with thick shortened processes. An increase in S100 protein was detected in all reactive astrocytes following LFP brain injury. Quantitative assessment of GFAP, S100, and vimentin polypeptides confirmed the immunohistochemical evaluation. Our data indicate that although astrogliosis mirrors the spatial pattern of post-traumatic neuronal cell loss, the expression of vimentin and the cellular morphology of the cells were regionally distinct, suggesting that astrogliosis may be modulated by factors present in the post-traumatic brain.

Animals↗

PubMed2004

Discovery of the novel candidate phylum "Poribacteria" in marine sponges.

Marine sponges (Porifera) harbor large amounts of commensal microbial communities within the sponge mesohyl. We employed 16S rRNA gene library construction using specific PCR primers to provide insights into the phylogenetic identity of an abundant sponge-associated bacterium that is morphologically characterized by the presence of a membrane-bound nucleoid. In this study, we report the presence of a previously unrecognized evolutionary lineage branching deeply in the domain Bacteria that is moderately related to the Planctomycetes, Verrucomicrobia, and Chlamydia lines of decent. Because members of this lineage showed <75% 16S rRNA gene sequence similarity to known bacterial phyla, we suggest the status of a new candidate phylum, named "Poribacteria", to acknowledge the affiliation of the new bacterium with sponges. The affiliation of the morphologically conspicuous sponge bacterium with the novel phylogenetic lineage was confirmed by fluorescence in situ hybridization with newly designed probes targeting different sites of the poribacterial 16S rRNA. Consistent with electron microscopic observations of cell compartmentalization, the fluorescence signals appeared in a ring-shaped manner. PCR screening with "Poribacteria"-specific primers gave positive results for several other sponge species, while samples taken from the environment (seawater, sediments, and a filter-feeding tunicate) were PCR negative. In addition to a report for Planctomycetes, this is the second report of cell compartmentalization, a feature that was considered exclusive to the eukaryotic domain, in prokaryotes.

Animals↗

PubMed1989

A morphology index for characterization of cell shape in Candida albicans.

The morphology of Candida albicans cells was determined from their maximum length, maximum diameter and septal diameter in a mathematical ratio, the morphology index (Mi), which usually ranged from approximately 1 for spherical yeast cells to approximately 4 for true hyphae, with elongated yeast cells and pseudohyphae giving intermediate values. Mi could be determined with high reproducibility for C. albicans grown in a variety of environments. The highest mean Mi was seen with cells grown in serum and Eagle's medium at 37 degrees C, the lowest with cells grown in Sabouraud glucose broth at 26 degrees C. Variant strains of C. albicans gave Mi values that remained constant in a variety of growth environments. The Mi facilitated detection of two variants that grew exclusively in the yeast form, one that grew as elongated yeasts but could be induced to form pseudohyphae in serum, and one consistently pseudohyphal variant. Cells with a mean Mi up to 2.5 could be easily separated at septal junctions by mild ultrasonication, whereas cells with a mean Mi greater than 3.5 tended not to separate under these conditions. The chitin content of C. albicans cells was almost twice as great in cells with a Mi approaching 4 as in cells with a Mi close to 1. The wide range of Mi distributions for a single C. albicans isolate in different environments demonstrates that the fungus does not undergo abrupt changes of morphological phase: rather there are continual changes in morphology between spherical yeasts and true hyphae at the extremes. The study shows that Mi can be used reliably in place of subjective descriptions of morphology to indicate the shape of a C. albicans cell. It should facilitate the detection of molecular and cellular markers specific for morphogenesis in the fungus.

Candida albicans↗

PubMed2004

Morphological and chemical characterizations of the interface of a hydroxyapatite-coated implant.

The present study aimed at morphological and chemical characterization of the coating-substrate interface of a commercially available dental implant coated with plasma-sprayed hydroxyapatite (HA). For this purpose, elements in the chemically and mechanically exposed substrate surfaces were analyzed by EPMA and XPS. A thin titanium oxide film containing Ca and P was found at the interface. When the implant was subjected to mechanical stress, a mixed mode of cohesive and interfacial fractures occurred. The cohesive fracture was due to separation of the oxide film from the substrate, while the interfacial fracture was due to exfoliation of the coating from the oxide film bonded to the substrate. Analysis showed diffusion of Ca into the metal substrate, hence indicating the presence of chemical bond at the interface. However, mechanical interlocking seemed to play the major role in the interfacial bond.

Calcium↗

PubMed1995

Surface morphology and chemical characterization of abrasion/erosion lesions.

PURPOSE: To describe the dentin surface morphology of abrasion/erosion lesions and to chemically characterize in vivo samples of sclerotic dentin. MATERIALS AND METHODS: Baseline polyvinylsiloxane impressions of eight in vivo caries-free lesions were taken. Dentin was collected from retention grooves for FTIR photoacoustic spectroscopic analysis. The cavity preparation was etched for 30 seconds with 37% phosphoric acid, rinsed, and dried. Impressions were taken of the etched surfaces. Epoxy resin dies were made of baseline and etched impressions, sputter-coated and examined at x1000 with the SEM. RESULTS: Lateral dentin tubule orientation was observed at gingival margins and on occlusal walls. Open cross-sectional tubules were seen at the depth of the groove. The mineral/protein ratio in the FTIR/PAS spectra of in vivo unetched sclerotic dentin samples suggested an increased mineral content.

Acid Etching, Dental↗