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Results for “Morphological Characterization”

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PubMed2003

Early Holocene human skeletal remains from Santana do Riacho, Brazil: implications for the settlement of the New World.

In this study we compare the cranial morphology of several late Paleoindian skeletons uncovered at Santana do Riacho, Central Brazil, with worldwide human cranial variation. Mahalanobis Distance and Principal Component Analysis are used to explore the extra-continental morphological affinities of the Brazilian Paleoindian sample. Santana do Riacho is a late Paleoindian burial site where approximately 40 individuals were recovered in varying states of preservation. The site is located at Lagoa Santa/Serra do Cipó, State of Minas Gerais. The first human activities in this rockshelter date back to the terminal Pleistocene, but the burials are bracketed between circa 8200 and 9500BP. The collection contains only six skulls well-enough preserved to be measured. The Santana do Riacho late Paleoindians present a cranial morphology characterized by long and narrow neurocrania, low and narrow faces, with low nasal apertures and orbits. The multivariate analyses show that they exhibit strong morphological affinities with present day Australians and Africans, showing no resemblance to recent Northern Asians and Native Americans. These findings confirm our long held opinion that the settlement of the Americas was more complicated in terms of biological input than has been widely assumed. The working hypothesis is that two very distinct populations entered the New World by the end of the Pleistocene, and that the transition between the cranial morphology of the Paleoindians and the morphology of later Native Americans, which occurred around 8-9ka, was abrupt. This, in our opinion, is a more parsimonious explanation for the diversity detected than a long, local microevolutionary process mediated by selection and drift. The similarities of the first South Americans with sub-Saharan Africans may result from the fact that the non-Mongoloid Southeast Asian ancestral population came, ultimately, from Africa, with no major modification in the original cranial bau plan of the first modern humans.

Animals↗

PubMed1986

Morphological and physiological properties of non-striated muscle from the tunicate, Ciona intestinalis: parallels with vertebrate skeletal muscle.

Non-striated muscle from the longitudinal body wall muscle in an adult ascidian (tunicate) is characterized morphologically and physiologically. These muscles are unique among chordate non-striated (i.e. 'smooth') muscles in that they are composed of discrete bundles of several small diameter (4-10 microns) muscle cells (fibers) arranged in parallel functional units. Each bundle is wrapped by a basal lamina, and at least some appear to be directly innervated at a neuromuscular junction similar to an end plate. In these regards, a bundle of Ciona smooth muscle cells is analogous to a skeletal muscle fiber of a vertebrate. This analogy also extends to physiological properties. Ciona muscle generates a rapid all-or-none Ca action potential which gives rise to a brisk twitch with brief latency. These anatomical and physiological adaptations are discussed in terms of the evolution of vertebrate skeletal muscle.

Action Potentials↗

PubMed2005

Molecular recognition in structured matrixes: control of guest localization in block copolymer films.

We demonstrate the use of molecular recognition to control the spatial distribution of guest molecules within block copolymer films. Block copolymers bearing recognition units were combined with complementary and noncomplementary molecules, and the extent of segregation of these molecules into the different domain types within microphase-separated thin films was quantitatively analyzed using dynamic secondary ion mass spectrometry (SIMS). Complementarity between the guest molecules and the polymer functionalities proved to be a key factor and an efficient tool for directing the segregation preference of the molecules to the different domain types. The effect of segregation preference on the glass transition temperature was studied using differential scanning calorimetry (DSC), and the results corroborate the SIMS findings. In a complementary study, guests with tunable sizes (via dendron substituents) were used to control block copolymer morphology. Morphological characterization using transmission electron microscopy (TEM) and X-ray diffraction reveal that selectivity differences can be directly translated into the ability to obtain different morphologies from recognition unit-functionalized block copolymer scaffolds.

Journal Article↗

PubMed2006

Use of PLGA scaffold for mucociliary epithelium transfer in airway reconstruction: a preliminary study.

CONCLUSION: A PLGA biodegradable membrane can be used as a scaffold for mucociliary epithelium transfer. OBJECTIVES: The aim of this study was to examine the usefulness of the PLGA membrane as a biodegradable scaffold for mucociliary epithelium transfer in order for it to be used as a substitute for a skin graft for restoring mucosal defects in the airway. METHODS: A PLGA biodegradable membrane was synthesized using the immersion precipitation method, and morphologic characterization was carried out using scanning electron microscopy (SEM). The degradation test was performed by soaking the PLGA membrane in a culture medium, and the morphological changes were observed by SEM. Human nasal basal epithelial (HNBE) cells were cultured on the newly synthesized PLGA membrane, and the morphological changes were analyzed using SEM. The MUC5AC and MUC8 mRNA levels were analyzed by RT-PCR. RESULTS: The PLGA membrane for the mucociliary epithelium transfer was successfully fabricated. It had a 24 mm diameter, a 50 microm thickness, and many pores with diameters of approximately 3 microm. The PLGA membrane began to degrade from 7 days after it was soaked in the culture medium. It rapidly degraded from 3 weeks and severe destruction of the pore structure was noted from 4 to 6 weeks of soaking. The HNBE cells were well differentiated into the mucociliary epithelium on the PLGA membrane both phenotypically and genotypically.

Absorbable Implants↗

PubMed2006

Form and function of ON-OFF amacrine cells in the amphibian retina.

ON-OFF amacrine cells were studied with whole cell recording techniques and intracellular staining methods using intact retina-eyecup preparations of the tiger salamander (Ambystoma tigrinum) and the mudpuppy (Necturus maculosus). Morphological characterization of these cells included three-dimensional reconstruction methods based on serial optical sections obtained with a confocal microscope. Some cells had their detailed morphology digitized with a computer-assisted tracing system and converted to compartmental models for computer simulations. The dendrites of ON-OFF amacrine cells have spines and numerous varicosities. Physiological recordings confirmed that ON-OFF amacrine cells generate both large- and small-amplitude impulses attributed, respectively, to somatic and dendritic generation sites. Using a multichannel model for impulse generation, computer simulations were carried out to evaluate how impulses are likely to propagate throughout these structures. We conclude that the ON-OFF amacrine cell is organized with multifocal dendritic impulse generating sites and that both dendritic and somatic impulse activity contribute to the functional repertoire of these interneurons: locally generated dendritic impulses can provide regional activation, while somatic impulse activity results in rapid activation of the entire dendritic tree.

Amacrine Cells↗

PubMed2000

Characterization of inflammatory reaction in upper airways of cystic fibrosis patients.

Inflammatory cell populations have not been yet precisely evaluated in cystic fibrosis (CF) airways. We intended to characterize morphological modifications, inflammatory cell infiltration and cell proliferation in nasal tissues obtained from 15 CF patients and from 6 non-CF patients with nasal polyposis. Morphological analysis showed an intense inflammatory infiltration in CF and non-CF tissues with only few modifications in the epithelium from CF tissues. Inflammatory cell populations characterized by specific immunolabeling were quantified, showing a predominance of macrophages and T- and B-lymphocytes and only moderate numbers of neutrophils in CF tissues; in non-CF polyps, lymphocytes and eosinophils were abundant. Proliferating cell percentages quantified after proliferating cell nuclear antigen immunolabeling were 5.3+/-4.1% (mean +/- SD) in CF polyps and 3.1+/-1.2% in non-CF polyps in epithelium but were very low in lamina propria. Intense inflammation in nasal tissues from CF patients is therefore dominated by macrophages and lymphocytes rather than by neutrophils. While morphology is preserved, proliferation is high in epithelium from CF polyps. These findings should be regarded in the future for a better understanding of inflammation in CF airway disease.

Adolescent↗

PubMed2003

Use of ribosomal DNA sequence data to characterize and detect a neogregarine pathogen of Solenopsis invicta (Hymenoptera: Formicidae).

A neogregarine parasite of the red imported fire ant, Solenopsis invicta, was discovered recently in Florida and tentatively placed in the Mattesia genus based on morphological characterization. S. invicta infected with this Mattesia species exhibited a characteristic yellowing of the cuticle which was designated Mattesia "yellow-head disease" (YHD). The 18S rRNA gene sequence from Mattesia YHD was elucidated and compared with the neogregarine pathogens, Mattesia geminata and Ophriocystis elektroscirrha. The sequence data support the previous conclusion that Mattesia YHD is a new species that infects S. invicta. Furthermore, high sequence identity between Mattesia YHD, M. geminata (95.7%), and O. elektroscirrha (86.2%) correctly place the YHD organism in the Mattesia genus and Neogregarinorida order. Oligonucleotide primer pairs were designed to unique areas of the 18S rRNA genes of Mattesia YHD and S. invicta. Multiplex PCR resulted in sensitive and specific detection of Mattesia YHD infection of S. invicta.

Animals↗

PubMed1982

Characterization of marrow-derived adherent cells. Evidence against an endothelial subpopulation.

Cultured, marrow-derived, adherent cells (MDAC) provide a microenvironment which supports the proliferation of haemopoietic stem cells (HSC) for extended periods in vitro. Morphological characterization suggested that MDAC populations consisted of a variety of cell types, including mononuclear phagocytes, fibroblastoid cells, fat cells and vascular endothelial cells. Recently performed functional characterization studies suggest that they consist largely of collagen-producing, fibroblastic cells. MDAC were not, however, examined systematically for endothelial cell characteristics. Unrecharged cultures of MDAC, shown in parallel studies to support in vitro haemopoiesis, were examined for endothelial cell markers. These included the presence of Weibel-Palade bodies and synthesis of factor VII related antigen. They were also examined biochemically for synthesis of basement membrane (type IV) collagen. The results of these investigations were negative in all cultures examined. It is thus concluded that vascular endothelial cells are not present as a significant component of the unrecharged MDAC population and do not, therefore, contribute to the functional haemopoietic microenvironment in vitro or in vitro.

Animals↗

PubMed1998

Hyalocyte-like cells are more numerous in the posterior chamber than they are in the vitreous of the rabbit eye.

The distribution and concentration of free cells inside the eye chambers of rabbits were investigated using semi-quantitative analysis of histological paraffin sections. Studies using light (methacrylate sections) as well as transmission and scanning electron microscopy were undertaken for the morphological characterization of the free cells. Immunocytochemistry and autoradiography were employed in an attempt to find out their nature and their origin, respectively. It was observed that cells morphologically similar to the vitreous hyalocytes were more numerous inside the posterior chamber than were the hyalocytes in the cortical vitreous. Neither the hyalocytes nor the posterior-chamber cells reacted with an antibody to rabbit macrophages. The finding of labeled free cells after an intravitreal injection of 3H-thymidine indicates that these cells can renew themselves and that their number does not depend exclusively on monocytes migrating from the blood stream to the eye chambers, as is believed to occur. In conclusion, hyalocytes or hyalocyte-like cells are more concentrated in the posterior chamber than they are in the vitreous. Both the hyalocytes and the posterior-chamber cells could not be characterized as fully developed macrophages.

Animals↗

PubMed1992

Morphological pathway of flagellar assembly in Salmonella typhimurium.

The process of flagellar assembly was investigated in Salmonella typhimurium. Seven types of flagellar precursors produced by various flagellar mutants were purified by CsCl density gradient protocol. They were characterized morphologically by electron microscopy, and biochemically by two-dimensional gel electrophoresis. The MS ring is formed in the absence of any other flagellar components, including the switch complex and the putative export apparatus. Four proteins previously identified as rod components, FlgB, FlgC, FlgF, FlgG, and another protein, FliE, assemble co-operatively into a stable structure. The hook is formed in two distinct steps; formation of its proximal part and elongation. Proximal part formation occurs, but elongation does not occur, in the absence of the LP ring. FlgD is necessary for hook formation, but not for LP-ring formation. A revised pathway of flagellar assembly is proposed based on these and other results.

Bacterial Proteins↗

PubMed2001

Morphologic features suggestive of gluten sensitivity in architecturally normal duodenal biopsy specimens.

We studied small bowel biopsy specimens with architecturally normal villi from 78 adult patients with potential gluten sensitivity (GS) and correlated them with outcome to characterize morphologic features that would allow a pathologist to suggest GS. No patient had a previous GS diagnosis. Twelve study patients had GS. The mean number of intraepithelial lymphocytes (IELs) per 20 enterocytes from the tips of 5 random villi was significantly greater in GS than non-GS biopsy samples, but the groups overlapped significantly, making the number diagnostically useful only when markedly increased. Crypt mitoses counts had similar relationships. Twelve patients had an even distribution of IELs along villus sides and over tips (3/66 [5%] non-GS patients, 9/12 [75%] GS patients). Non-GS patients had a decrescendo pattern of IELs along the sides of villi. Architecturally normal small bowel biopsy specimens with an appreciable, continuous, even distribution of IELs along the sides and tips of villi and a mean of 12 or more IELs in the tips of several villi are suggestive of GS. Pathologists should be watchful for these morphologic features in small bowel biopsy specimens to suggest GS.

Adolescent↗

PubMed2000

The orphan receptor serine/threonine kinase ALK7 signals arrest of proliferation and morphological differentiation in a neuronal cell line.

The signaling capabilities and biological functions of activin receptor-like kinase 7 (ALK7), a type I receptor serine/threonine kinase predominantly expressed in the nervous system, are unknown. We have constructed a cell line derived from the rat pheochromocytoma PC12 in which expression of a constitutively active mutant of ALK7 (T194D) is under the control of a tetracycline-inducible promoter. For comparison, another cell line was engineered with tetracycline-regulated expression of a constitutively active variant of the transforming growth factor-beta type I receptor ALK5. Expression of activated ALK7 in PC12 cells resulted in activation of Smad2 and Smad3, but not Smad1, as well as the mitogen-activated protein kinases extracellular signal-regulated kinase and c-Jun N-terminal kinase. Reporter assays demonstrated that ALK7 activation stimulates transcription from the Smad-binding element of the Jun-B gene, the plasminogen activator inhibitor-1 gene, and AP-1 elements. In addition, ALK7 activation induced expression of endogenous gene products, including Smad7, c-fos mRNA, and plasminogen activator inhibitor-1. Thymidine incorporation assays revealed an anti-proliferative effect of ALK7 activation in PC12 cells, which correlated with increased transcription from the promoters of cycline-dependent kinase inhibitors p15(INK4B) and p21. Unexpectedly, ALK7 signaling produced a remarkable change in cell morphology characterized by cell flattening and elaboration of blunt, short cell processes. Interestingly, no such changes were observed upon induction of activated ALK5. The alterations in cell morphology upon ALK7 activation were more pronounced in cultures grown in full serum, were accompanied by rearrangements of actin filaments, and were maintained for several days after withdrawal of treatment. PC12 cultures that had been "primed" in this way showed an accelerated and augmented differentiation response to nerve growth factor. These results indicate that ALK7 may participate in the control of proliferation of neuronal precursors and morphological differentiation of postmitotic neurons.

Actins↗

PubMed1983

Alterations of human endometrial stromal cells produced by N-methyl-N'-nitro-N-nitrosoguanidine.

Stromal cell cultures obtained from human endometrium were treated repetitively with N-methyl-N'-nitro-N-nitrosoguanidine in vitro at concentrations ranging from 0.5 to 4.0 micrograms/ml, and alterations in growth potential and morphology were analyzed. A single exposure to the carcinogen resulted in morphological evidence of toxicity and reductions in growth rates, plating efficiency, and saturation density as compared to solvent-treated control cells. Cytotoxicity was reduced after additional exposures to the carcinogen. Following repetitive treatments with N-methyl-N'-nitro-N-nitrosoguanidine, human endometrial stromal cells developed enhanced growth potential, the capacity to form macroscopic colonies in soft agar, and elevated gamma-glutamyltranspeptidase activity. Carcinogen-treated cells displayed atypical morphology characterized by irregularities in cell and nuclear size and shape, large bizarre nucleoli, increased nuclear:cytoplasmic ratios, and cellular crowding. Control cells did not display altered morphology or growth parameters even following multiple exposures to solvent and repetitive subculturing. These alterations in growth potential and morphology suggest that the cells are progressing towards preneoplastic and perhaps neoplastic transformation in vitro.

Agar↗

PubMed1993

Demonstration of extensive chromatin cleavage in transplanted Morris hepatoma 7777 tissue: apoptosis or necrosis?

Cell death may occur by either of two mechanisms: necrosis or apoptosis (programmed cell death). In this paper, we demonstrate extensive chromatin cleavage into oligonucleosome-length fragments (DNA ladder) in transplanted Morris hepatoma 7777 tissue, which is suggestive of the stimulation of an endogenous endonuclease activity previously found to be involved in the process of apoptosis. The existence of many apoptotic cells, which are morphologically characterized by condensed cytoplasm and basophilic nuclear fragments, were also seen in this tissue. In vivo and in vitro experiments were designed to further differentiate the morphological and biochemical features of necrosis and apoptosis in liver and hepatoma cells. Liver tissue undergoing ischemic necrosis showed a distinct DNA ladder pattern without demonstrating the morphology of apoptosis, indicating that chromatin cleavage into oligonucleosomal-length fragments is not confined to apoptotic cell death, at least in liver cells. In in vitro-cultured McA-RH7777 cells, however, DNA ladder pattern was detected only in cells showing characteristic morphology of apoptosis. From these two criteria (i.e., characteristic morphology and DNA ladder), it was strongly suggested that the apoptotic process is highly activated in the transplanted 7777 tissue. Based on the results obtained from in vitro experiments, it was suggested that tumor apoptosis may represent a residual attempt at autoregulation within the expanding tumor population and/or may result from mild cellular injuries such as hypoxia, nutrient deficiency, or other unknown noxious factor(s). We also showed evidence that apoptosis is inducible in hepatoma cells in vitro by a wide range of mild injuries or stimuli.

Animals↗

PubMed2000

Clinical and pathologic aspects of spontaneous canine prostate carcinoma: a retrospective analysis of 76 cases.

BACKGROUND: Pet dogs and men share a vulnerability for the development of prostate carcinoma. The purpose of this study was to further characterize the clinical and pathologic features of spontaneous canine prostate carcinoma. METHODS: A multiinstitutional, retrospective study was conducted using 76 dogs with prostate carcinoma that underwent postmortem evaluation. For each case, clinical and pathologic data were tabulated and hematoxylin/eosin-stained tissue sections from the primary tumor and metastatic lesions were evaluated. Prostatic carcinomas were subclassified based upon the presence of glandular, urothelial, squamoid, or sarcomatoid differentiation. We focused our analysis on dogs that differed with respect to morphologic features of the primary tumor, lifetime duration of testicular hormone exposure, and presence of skeletal metastases. RESULTS: The vast majority of canine prostate carcinomas affected elderly sexually intact dogs or dogs that underwent surgical castration after sexual maturity. Adenocarcinoma was the most frequent histologic type, although more than half of canine prostate carcinomas exhibited intratumoral heterogeneity. In many cases, primary tumors showed mixed morphology, characterized by two or more types of differentiation. Duration of testicular hormone exposure was significantly different between dogs with adenocarcinoma and dogs with mixed morphology tumor, but did not appear to influence the frequency or pattern of metastases. Overall, gross metastases were present in 80% of dogs with prostate carcinoma. Skeletal metastases were present in 22% of cases, and the predominantly axial skeletal distribution of these lesions was similar to that reported in men with prostate carcinoma. Young dogs were at highest risk for development of skeletal metastases. CONCLUSIONS: This study provides a more complete characterization of spontaneous prostate carcinoma of dogs in terms of morphologic heterogeneity, skeletal metastases, and the influence of testicular hormones. Prostate carcinoma in pet dogs provides an immunocompetent, autochthonous tumor system that mimics certain aspects of human prostate cancer. This spontaneous model may contribute to our understanding of the factors that regulate carcinogenesis within the aged prostate, and to the development of chemoprevention strategies or bone-targeted therapies.

Adenocarcinoma↗

PubMed1981

Morphologic and biochemical characteristics of isolated and cultured pancreatic ducts.

Rat and hamster pancreatic ducts were isolated by digestion with collagenase plus chymotrypsin and were cultured for eight weeks in an agarose matrix. Freshly isolated and cultured ducts were characterized morphologically and biochemically. The in vivo morphology of the ducts was maintained in vitro, although certain differences were noted. Both interlobular and intralobular ducts could be identified. gamma-Glutamyltranspeptidase and Mg-ATPase were stable enzymatic activities of the ducts of both species; alkaline phosphatase persisted only in the hamster ducts. Carbonic anhydrase and (Na + K)ATPase were minor activities of the rat ducts. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the rat ducts suggested that actin was the major duct peptide and that the major zymogens were greatly diminished. These results demonstrate that pancreatic ducts can be maintained in vitro and can be used for biochemical studies of this minor pancreatic tissue type.

Adenosine Triphosphatases↗

PubMed2002

Tissue engineering of functional trileaflet heart valves from human marrow stromal cells.

BACKGROUND: We previously demonstrated the successful tissue engineering and implantation of functioning autologous heart valves based on vascular-derived cells. Human marrow stromal cells (MSC) exhibit the potential to differentiate into multiple cell-lineages and can be easily obtained clinically. The feasibility of creating tissue engineered heart valves (TEHV) from MSC as an alternative cell source, and the impact of a biomimetic in vitro environment on tissue differentiation was investigated. METHODS AND RESULTS: Human MSC were isolated, expanded in culture, and characterized by flow-cytometry and immunohistochemistry. Trileaflet heart valves fabricated from rapidly bioabsorbable polymers were seeded with MSC and grown in vitro in a pulsatile-flow-bioreactor. Morphological characterization included histology and electron microscopy (EM). Extracellular matrix (ECM)-formation was analyzed by immunohistochemistry, ECM protein content (collagen, glycosaminoglycan) and cell proliferation (DNA) were biochemically quantified. Biomechanical evaluation was performed using Instron(TM). In all valves synchronous opening and closing was observed in the bioreactor. Flow-cytometry of MSC pre-seeding was positive for ASMA, vimentin, negative for CD 31, LDL, CD 14. Histology of the TEHV-leaflets demonstrated viable tissue and ECM formation. EM demonstrated cell elements typical of viable, secretionally active myofibroblasts (actin/myosin filaments, collagen fibrils, elastin) and confluent, homogenous tissue surfaces. Collagen types I, III, ASMA, and vimentin were detected in the TEHV-leaflets. Mechanical properties of the TEHV-leaflets were comparable to native tissue. CONCLUSION: Generation of functional TEHV from human MSC was feasible utilizing a biomimetic in vitro environment. The neo-tissue showed morphological features and mechanical properties of human native-heart-valve tissue. The human MSC demonstrated characteristics of myofibroblast differentiation.

Absorbable Implants↗

PubMed1995

Morphological factors influencing transepithelial conductance in a rabbit model of ileitis.

BACKGROUND & AIMS: Infection of rabbits with coccidia (Eimeria magna) causes chronic ileal inflammation and diarrhea. Inflamed ileum also shows decreased transmural conductance. The aim of this study was to characterize morphological factors known to affect paracellular permeability that may alter transmural conductance in inflamed ileum. METHODS: Ileal mucosa was mounted in Ussing chambers for study of [3H]mannitol and [3H]inulin fluxes. Light and electron microscopy were used for morphometric studies. Alterations in the zonula occludens of epithelial cells were evaluated in freeze-fracture replicas. RESULTS: Inflamed ileum showed diminished paracellular fluxes. Inoculated rabbits showed marked lymphoplasmocytic infiltration and villus blunting in ileum. Villus linear junctional density was unaffected. However, total villus apical surface area per square centimeter of tissue was reduced in inflamed ileum, causing a diminished total villus linear junctional pathway per square centimeter of apical surface. Villus zonula occludens strand number was reduced in inflamed ileum, whereas the frequency of both villus and crypt lateral surface extrajunctional strands increased. CONCLUSIONS: Chronic inflammation exerts a profound effect on ileal paracellular permeability. Morphological data suggest that this effect may be caused in part by alterations in inflamed ileal mucosal structure and tight junctional organization and density, particularly on villi.

Animals↗