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Results for “Digitation junction”

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At least 19 recordsLinked to original sources
PubMed1991

The potential role of the ovine pharyngeal tonsil in respiratory tract immunity: a scanning and transmission electron microscopy study of its epithelium.

The mucosal epithelium of the pharyngeal tonsil was studied in 10 conventionally raised sheep by scanning and transmission electron microscopy. The surface of the tonsil was covered by two types of topographically and ultrastructurally distinct epithelium. The epithelium overlying the lymphoid follicle region (follicle-associated epithelium) was compressed by adjacent ciliated epithelium and consisted of predominantly non-ciliated cells of varying height. The majority of these cells possessed microvilli or microfolds of varying number, height and density on their surface. Small numbers of squamous cells and, occasionally, intermediate cells were also present in these areas. Ultrastructurally, the microvillous cells showed features similar to M cells which occur in other mucosal sites. They contained cytoplasmic vesicles and vacuoles and formed intercellular digital junctions. Between these cells was a heavy infiltration of lymphoid cells. Focal disintegration of the mucosal epithelium was occasionally seen. The epithelium covering non-follicle areas consisted of mainly ciliated cells interspersed with some goblet cells and squamous cells, morphologically resembling those elsewhere in the respiratory tract. These findings have provided evidence which confirms that the ovine pharyngeal tonsil is part of the respiratory tract-associated lymphoid tissue.

Animals↗
PubMed2026

Interaction between CD82 and integrin αVβ3 selectively regulates collective movement of tumor cells via endolysosomal trafficking.

Tetraspanin CD82/KAI1 inhibits cell movement and metastasis of malignant tumors, and reduced and lost expressions of CD82 predict worse outcomes of patients with malignant tumors. Here we found that CD82 inhibits both solitary and collective movement of tumor cells. The CD82 YVAA mutation, which affects CD82 trafficking, selectively abrogates CD82-mediated inhibition of collective migration. Cilengitide, at the concentration that specifically inhibits integrin αVβ3, also selectively blocks collective movement, underscoring a promotive role of integrin αVβ3 in this mode of cell motility. In contrast, integrin αVβ5 appears non-essential for collective migration, and both αVβ3 and αVβ5 are dispensable for solitary movement on fibronectin, highlighting distinct functions of different integrins in different modes of tumor cell movement. CD82 interacts with αVβ3 and αVβ5 integrins and downregulates their protein levels, while CD82 YVAA mutation relinquishes this downregulation without disrupting CD82 interactions with these integrins. Mechanistically, CD82, but not the YVAA mutant, considerably reduces digitation junction-the structure where integrin αVβ3 localizes-and likely directs integrin αVβ3 for lysosomal degradation, thereby lowering its level and suppressing collective migration. Thus, our study reveals that i) integrin αVβ3 promotes collective movement of tumor cells, ii) CD82 counteracts this by diminishing integrin αVβ3 and its presence in microextrusions, and iii) digitation junction likely participates in collective cell movement. Our study further demonstrates that endolysosomal trafficking of CD82 and integrin αVβ3 is needed for their collective movement-regulatory activities and that coupling of metastasis suppressor CD82/KAI1 with different partners regulates different modes of cell movement.

Humans↗
PubMedDate not supplied

[Sclerotherapy of the internal saphenous vein in the standing and sitting position. A comparative study].

A study was undertaken to compare two methods of sclerosing injection of the sapheno-femoral junction (SFJ). The study involved a sample of 2186 patients. In the first method, with the patient in sitting position, injections were administered below the junction with digital compression applied directly to the SFJ. In the second method, with the patient in standing position, injections were administered below the junction with digital compression applied directly to the junction as well as below the injection site. Results showed that sequestration of the proximal saphenous segment with the patient in standing position is a valid technique for the treatment by sclerosing injections of incompetence of the long saphenous.

Adult↗
PubMed1990

Two different techniques for sclerosing the incompetent saphenofemoral junction: a comparative study.

A study comparing two methods of sclerosing the saphenofemoral junction (SFJ) that included 2186 patients was conducted. In the first method, injections were made below the junction with digital pressure applied at the SFJ, with the patient in a sitting position. In the second, injections were made below the junction with digital pressure at the SFJ and below the injection site, with the patient in a standing position. The results indicated that higher saphenous sequestration with the patient in a standing position is a valuable sclerotherapy technique.

Adult↗
PubMedDate not supplied

[Sclerosis of junctions combined with compression: long-term results].

The authors present long term results of sapheno-femoral junction injection with digital compression of the junction during the injection. The results were tabulated on the first one hundred cases seen at random 6 to 10 years after treatment. They conclude that this method is of great value for most patient with long saphenous vein insufficiency.

Female↗
PubMed1979

Alterations of the cell surface morphology in human T-rosetting lymphocytes. An ultrastructural study.

A study of E-rosette ultrathin sections has been undertaken in an attempt to analyze changes induced during the T-lymphocyte-sheep red blood cell interaction on the rosetted lymphocyte surface architecture. The formation of nonimmune rosettes implies different types of attachment between lymphocytes and sheep red blood cells which can affect the rosetted lymphocyte surface morphology: (a) Junctions not involving morphological changes which correspond to bands or point-to-point contact sites. (b) Junctions displaying localized morphological changes, which are revealed mainly in the form of microvilli or digitations. (c) Junctions involving broad morphological changes, revealed primarily by the development of various microvilli or other more complex structures. In both cases, the alterations are found only in those areas of the lymphocyte membrane-bound sheep red blood cells. The modifications that affect the rosetted lymphocyte make the validity of the E-rosette test questionable for studies aiming at the analysis of the lymphocyte surface architecture.

Animals↗
PubMed1985

Three-dimensional distribution of neuromuscular junctions in human cricothyroid.

Microinjections of myoneural blocking agents are effective in the treatment of strabismus and have been proposed as a possible technique to treat spastic dysphonia. The success of such a technique would rely on a precise knowledge of the neuromuscular junction distribution in the laryngeal muscle to be injected. In view of the possibility of an involvement of the cricothyroid muscle in spastic dysphonia or other neuromuscular disorders, we determined the three-dimensional distribution of neuromuscular junctions in the human cricothyroid muscle. Cricothyroid muscles obtained from autopsy cases were fixed, sectioned, and processed for the histochemical localization of neuromuscular junction acetylcholinesterase. Using serial sections and a computer interfaced X-Y digitizer, the neuromuscular junctions were referenced to various anatomic landmarks and the neuromuscular junction distribution and reconstructed in three dimension using computer graphics.

Computers↗
PubMed1992

Immunolabelling patterns of gap junction connexins in the developing and mature rat heart.

The distribution of gap junctions in prenatal, postnatal, and adult rat hearts was studied by laser scanning confocal microscopy, using antiserum raised to a peptide (HJ) matching part of the sequence of connexin43 (a cardiac gap junction protein). Using digital reconstruction of optically-sectioned tissue volumes, a highly sensitive detection of immunolabelled gap junctions was achieved. The distribution of positive anti-HJ immunolabelling was regionalised in the prenatal heart from its first detection at 10 days post-coitus. High levels of immunopositive staining occurred in the trabeculae of the embryonic ventricles. Other zones of the early myocardium including early central conduction tissues had no detectable signal. The prenatal outflow tract, interventricular septum and a narrow zone of myocardium subjacent to the epicardial free wall also had low levels of immunopositive signal. During postnatal growth and in the adult rat heart, a marked distinction emerged between the central conducting tissues of the atria and ventricles. Whilst small immunostained gap junctions became detectable within the atrioventricular node on the atrial side of the junction, between the interatrial and interventricular septa, no immunolabelling was found within the ventricular branching bundle. This difference between the atrioventricular node and branching bundle is consistent with potential functional distinctions between these two structures, and is not consistent with the recent proposal that the His bundle and its branches act as an extended atrioventricular node in smaller mammals such as the rat. Ventricular Purkinje fibres, distal to the branching bundle, showed high levels of anti-HJ immunostaining. Organisation of gap junctions into intercalated disks within the ventricle proceeded late into intercalated disks within the ventricle proceeded late into the adolescent stages of heart growth. The distribution of a second connexin protein, MP70, not previously characterised in the heart, was studied using monoclonal antibodies. MP70 was transiently immunolabelled in the heart during the postnatal period, but only within valves. Previously, this protein has been reported only in the eye lens. MP70-containing gap junctions may represent a specialisation in avascular tissues, since blood vessels are not present in either the eye lens or the cusps of heart valves.

Animals↗
PubMed1990

Mycotic aneurysm in a digital artery: case report and literature review.

A mycotic aneurysm of the common digital artery at its junction with the palmar arch, extending into the ulnar proper digital artery of the index finger, is reported in a patient with endocarditis. A review of the English-language literature revealed no case of mycotic aneurysm in a digital artery. Diagnosis of the aneurysm was established noninvasively by ultrasound. Because this patient lacked a radial proper digital artery to the finger, the aneurysm was managed by excision and revascularization with a bypass graft from the long finger. Postoperative circulatory monitoring was facilitated by a pulse oximeter.

Aged↗
PubMed1987

Fluorimetry of bovine myotendon junction by fibre-optics and microscopy of intact and sectioned tissues.

The autofluorescence of tendon, epimysium and endomysium at the myotendon junction of the deep digital flexor in the bovine forelimb was measured with a fluorescence microscope and with a bifurcated light guide composed of quartz optical fibres. Data were adjusted for spectral variation in the radiance of the halogen illuminator used to standardize the photometer. Samples of myotendon junction were examined intact, in slices several millimetres thick and after being frozen in liquid nitrogen and sectioned at 20 micron. Sections were examined with and without a mounting medium and with and without immersion oil objectives. Type I collagen fibres were identified by their scarcity of branching, relatively large size and yellow staining with silver. Type III collagen fibres were identified by their extensive branching, small size and black staining with silver. Purified Types I and III collagen were also examined. Type I collagen fibres had a strong fluorescence emission peak between 410 and 450 nm and a shoulder at 510 nm. For the strong peak, results obtained by fibre-optics were positively biased relative to those obtained by microscopy. Type III collagen reticular fibres lacked a strong emission peak at 410 to 450 nm. Although their overall fluorescence was weaker than that of Type I collagen fibres, Type III collagen fibres had similar or slightly stronger emissions around 510 nm. The Type I emission spectrum of collagen fibres was converted to a spectrum similar to the Type III spectrum by conditions that caused the fading of fluorescence (storage as dry or mounted sections and exposure of sections to UV light).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

The areas ratio of normal arterial junctions and its implications in pulse wave reflections.

STUDY OBJECTIVE: The aim of the study was to establish measurements for the area ratios of normal arterial junctions at various anatomical sites in order to estimate the significance of pulse wave reflections in the healthy arterial system. DESIGN: Coronary cineangiograms were used for the coronary junctions measurements and routine arteriograms for the rest of the junctions studied. A pair of digital calipers served to take measurements at a distance of one vessel diameter from the junction centre. MEASUREMENTS AND MAIN RESULTS: A bell shaped distribution of arterial area ratios was found with mean value for coronary bifurcations of 1.179 (95% confidence limits, 1.138-1.220). Slightly higher values were found for the higher order coronary junctions. Other junctions had similar area ratio values with the exception of the aortoiliac junctions where the area ratio was found 0.848 (0.775-0.920). Overall area ratio was 1.14 (1.113-1.167). Asymmetrical coronary bifurcations had higher area ratio than symmetrical ones (p less than 0.05). CONCLUSIONS: In the majority of cases the area ratios are in close agreement with the theoretically predicted values for forward matched junctions. Minimal pulse wave reflections are therefore expected to arise from the junctions of a healthy arterial system. We therefore consider that, contrary to the established view, the presence of reflected waves in the central arterial system is a potential pathological phenomenon and not a characteristic of the healthy system. This may have important theoretical implications for the way hemodynamic findings are interpreted. Finally we suggest that arterial area ratio can be considered as another criterion of normality of arterial junctions in the interpretation of angiograms.

Anthropometry↗
PubMed1991

[Free toe transfer with plantar metatarsal arteries and dorsal venous pedicle. Report of 18 cases].

Eighteen free second toe were used for pollicization other than the conventional method. From the first and second plantar metatarsal arteries junction of the both digital arteries of the second toe were dissected retrogradely and anastomosed to the deep of superficial palmar arch or terminal branch of the radial artery. The venous return was established between the dorsal venous arch and cephalic vein. These vessels were found to have much bigger diameters and less anatomical variation than those used by conventional methods. Seventeen transplantation were considered successful both functionally and cosmetically. One cases had persistent spasmodic contraction of the recipient arteries, so the transplant was salvaged by subclavicular pedicle including the sutured nerves and the attached soft tissues as introduced by Lu in 1964. Our method for reconstruction of the thumb or finger can avoid frequent anatomical variation and smaller diameter of the anastomosed vessels.

Adult↗
PubMed1976

The motor end plate in myasthenia gravis and in experimental autoimmune myasthenia gravis. A quantitative ultrastructural study.

Neuromuscular junction ultrastructure in rat forelimb digit extensor muscle was sequentially and quantitatively investigated in experimental autoimmune myasthenia gravis (EAMG). Experimental animals received a single dose of highly purified eel-electroplax acetylcholine receptor protein plus complete Freund's adjuvant and B. pertussis organisms. During the first 7 days (latent period) after immunization the experimental end plates remained normal. Between day 7 and 11 (acute phase) mononuclear cells infiltrated those regions of muscle where the end plates were located and the was sudden degeneration of the postsynaptic regions with splitting away of the abnormal junctional folds from the underlying muscle fibers. Macrophages entered the gaps arising between the muscle fibers and the separating postsynaptic folds and removed the degenerating folds by phagocytosis. The nerve terminals were displaced from their usual location but maintained their structural integrity. After day 11 (chronic phase) the inflammatory reaction subsided and the nerve terminals returned to the highly simplified postsynaptic regions. Subsequently the postsynaptic folds were reconstituted and again they degenerated. The degeneration involved especially the tips of the folds where acetylcholine receptor sites are concentrated. Immature junctions with poorly differentiated postsynaptic regions and nerve sprouts near end plates were also observed. In two animals that relapsed on day 27 and 33, respectively, degeneration of the postsynaptic folds was more intense than in the remaining animals that had not relapsed during the chronic phase. Morphometric analysis of the end plates demonstrated significant decreases in the postsynaptic membrane length, in the postsynaptic membrane density and in the postsynaptic to presynaptic membrane length ratio in chronic EAMG. In addition, the concentration of synaptic vesicles in the nerve terminals was increased in acute and chronic EAMG while the nerve terminal area was decreased in acute EAMG. The alterations in the nerve terminal may be secondary to the postsynaptic changes. The postsynaptic region is the primary target of the autoimmune reaction in EAMG and the ultrastructural and morphometric abnormalities of the end plate in the chronic phase of the syndrome closely resemble those which have been observed in human myasthenia gravis.

Animals↗
PubMedDate not supplied

Experimental autoimmune myasthenia gravis: a sequential and quantitative study of the neuromuscular junction ultrastructure and electrophysiologic correlations.

Neuromuscular junction ultrastructure in rat forelimb digit extensor muscle was sequentially and quantitatively investigated in experimental autoimmune myasthenia gravis (EAMG). Experimental animals were immunized with highly purified eel electroplax acetylcholine receptor protein plus complete Freund's adjuvant and B pertussis vaccine; control animals received only adjuvant and vaccine. During the first 7 days (latent period) after immunization end-plate structure and neuromuscular transmission remained normal in the experimental group. Between day 7 and 11 (acute phase) mononuclear cells infiltrated those regions of muscle where the end-plates were located and there was intense degeneration of the postsynaptic regions with splitting away of abnormal junctional folds from the underlying muscle fibers. Macrophages entered the gaps thus formed and removed the degenerating folds by phagocytosis. The nerve terminals were displaced from their usual location but maintained their structural integrity. Neuromuscular transmission was blocked in many muscle fibers. Miniature end-plate potentias (MEPPs), detectable in only a few fibers, were of abnormally low amplitude. After day 11 (chronic phase) the nerve terminals returned to the highly simplified postsynaptic folds became reconstituted and again degenerated. Immature junctions with poorly differentiated postsynaptic regions and nerve sprouts near end-plates were also observed. In two animals relapsing during the chronic phase degeneration of the postsynaptic folds was more intense than in the other chronic-phase animals. The posysynaptic membrane length and length per unit area and the MEPP amplitudes were significantly decreased in all chronic phase animals and the decreases were greater in the relapsing than in the non-lapsing animals. Minor morphometric alterations were also observed in the nerve terminals. These might have been secondary to the postsynaptic changes. The postsynaptic region is the primary target of the autoimmune reaction in EAMG. The ultrastructural, morphometric and electrophysiological abnormalities of the end-plate in chronic EAMG resemble those which have been observed in human myasthenia gravis.

Animals↗
PubMed1988

Morphological study of cerebellar transplant cocultivated with cerebral cortical graft in the anterior eye chamber. I. Granular layer.

Fetal cerebral cortex and cerebellar anlage from rat fetuses of 15-16 gestational day were grafted simultaneously to the anterior eye chamber of adult female albino rat recipients. Two months after transplantation the cerebellar portion of the double graft consisted of foliated cerebellar cortex surrounding a well-defined cerebellar nucleus. In the absence of pia mater or glial scar the cerebral and cerebellar grafts were observed to establish direct contact with each other. Although much thinner than in the normal cerebellum, the overall morphological organization of the granular layer in the transplant was similar to that described for "in situ" normal cerebellum, with some remarkable differences, though. In normal cerebellum all mossy terminals contain spheroid synaptic vesicles, a characteristic morphological feature of excitatory endings. In the transplant, however, although the majority of mossy terminals contained (small or large) spheroid synaptic vesicles, numerous mossy terminals were filled with ovoid, or pleomorphic synaptic vesicles, a morphological marker of inhibitory terminals. GABA-immunogold reaction, revealed, indeed, the presence of this inhibitory transmitter in mossy terminals containing ovoid synaptic vesicles. Both GABA (-) and GABA (+) mossy terminals formed asymmetric (Gray I-type) synaptic junctions with the surrounding dendritic digits of granule cells. It is suggested that GABA-ergic fibers as well as most non-GABA-ergic axons (originating either from the cerebral cortical graft, or from the cerebellar nucleus) may develop to mossy terminal-like structures as a consequence of the hugh deficit in "natural" mossy fibers in this model.

Animals↗
PubMed1987

Calcium-induced assembly of adherens junctions in keratinocytes.

Extracellular calcium concentration has been shown to control the stratification of cultured keratinocytes, presumably by regulation of formation of desmosomes. Previous studies have shown that keratinocytes cultured in medium containing 0.1 mM Ca++ form loose colonies without desmosomes. If the Ca++ is raised to 1 mM, desmosomes are assembled and the distribution of keratin filaments is altered. We have examined the disposition of vinculin and actin in keratinocytes under similar conditions. Using immunofluorescence microscopy we show that raising [Ca++] in the medium dramatically alters the distribution of vinculin and actin and results in the formation of adherens-type junctions within 15 min after switching to high calcium medium. Borders of cells at the edge of colonies, which are not proximal to other cells, are not affected, while cells in the interior of the colony form junctions around their periphery. Attachment plaques in keratinocytes grown in low calcium medium are located at the ventral plane of the cell, but junctions formed after switching to high calcium are not, as demonstrated by interference reflection microscopy. In cells colabeled with antibodies against vinculin and desmoplakin, vinculin-containing adherens junctions were visible before desmosomal junctions when cells were switched to high calcium. Although newly formed vinculin-containing structures in high calcium cells, like desmosomes, colocalize with phase-dense structures, superimposition of video fluorescence images using digitized fluorescence microscopy indicates that adherens junctions and desmosomes are discrete structures. Adherens junctions, like desmosomes, may play an essential role in controlling stratification of keratinocytes.

Actins↗
PubMed1992

Intercellular calcium signaling via gap junctions in glioma cells.

Calcium signaling in C6 glioma cells in culture was examined with digital fluorescence video microscopy. C6 cells express low levels of the gap junction protein connexin43 and have correspondingly weak gap junctional communication as evidenced by dye coupling (Naus, C. C. G., J. F. Bechberger, S. Caveney, and J. X. Wilson. 1991. Neurosci. Lett. 126:33-36). Transfection of C6 cells with the cDNA encoding connexin43 resulted in clones with increased expression of connexin43 mRNA and protein and increased dye coupling, as well as markedly reduced rates of proliferation (Zhu, D., S. Caveney, G. M. Kidder, and C. C. Naus. 1991. Proc. Natl. Acad. Sci. USA. 88:1883-1887; Naus, C. C. G., D. Zhu, S. Todd, and G. M. Kidder. 1992. Cell Mol. Neurobiol. 12:163-175). Mechanical stimulation of a single cell in a culture of non-transfected C6 cells induced a wave of increased intracellular calcium concentration ([Ca2+]i) that showed little or no communication to adjacent cells. By contrast, mechanical stimulation of a single cell in cultures of C6 clones expressing transfected connexin43 cDNA induced a Ca2+ wave that was communicated to multiple surrounding cells, and the extent of communication was proportional to the level of expression of the connexin43 cDNA. These results provide direct evidence that intercellular Ca2+ signaling occurs via gap junctions. Ca2+ signaling through gap junctions may provide a means for the coordinated regulation of cellular function, including cell growth and differentiation.

Calcium↗
PubMed1986

Flexor tendon lengthening by tenotomy at the musculotendinous junction.

The author presents his experience with an established technique of flexor tendon lengthening by tenotomy at the musculotendinous junction. This technique can be used for digital stiffness of forearm origin when active extension is possible on flexion of the wrist. There must not be adherence in the carpal tunnel or in the digital sheath, and active flexion must be preserved. It can also be used for digital stiffness in addition to other techniques. This kind of lengthening has some advantages: there are no sutures in the tendon itself, and it allows early reeducation in association with dynamic extension splinting. Active flexion is preserved immediately and there is good tendon healing. It is possible to lengthen selectively the superficial flexor or the deep flexor and in some cases both. Results are presented according to cause.

Adult↗