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PubMed1981

Ultrastructural relationships between the receptor nerve fiber and surrounding lamellae in Krause end-bulbs.

The ultrastructural relationship between the receptor nerve fiber and the surrounding lamellae in Krause end-bulbs was discussed. Many sites of specialized junctions of symmetrical or asymmetrical type along the receptor nerve fiber and the surrounding lamellae were found. In addition, in close vicinity to them, spine-like digitations of the receptor nerve fiber, filled mainly with small clear vesicles, were observed. Mitochondrion-like cholinesterase-positive structures bulging in some cytoplasmic lamellae were also found. It is suggested that a functional link might exist between the specialized junctions, digitations and mitochrondrion-like structures in the transformation of external mechanical stimuli into nerve impulses.

Animals↗
PubMed1980

Digital artery sympathectomy.

A very distal sympathectomy at the level of the origin of the proper digital arteries has been devised. Four men and four women have been operated on for digital vascular insufficiency due to frostbite, crush injuries, scleroderma, and Raynaud's disease. The operation is done through a palmar approach and the adventitia removed, over a length of 3 to 4 mm, from the proper digital arteries distal to the junction of the distal perforating artery with the common digital artery. Three frostbite victims have done well; their ulcers have healed, pain symptoms have improved, and a skin temperature rise of 1.5 degrees to 2.5 degrees F has persisted over a 17-year follow-up. Two crushed fingers have shown some, but not impressive, permanent symptomatic improvement. Three women had four operations for Raynaud-type disease. Two of the women, 40 and 41 years of age, showed a permanent skin temperature rise of only 2 degrees and 1 degree F, respectively. They showed significant, but not total, pain relief. The third woman, 22 years of age, had atrophic, curled index and thumb nails. After sympathectomy, the nails grew normally, there was significant pain relief, and the patient showed a permanent 3 degrees F rise in skin temperature.

Adult↗
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↗
PubMed2005

Microsurgical anatomy and quantitative analysis of the transtemporal-transchoroidal fissure approach to the ambient cistern.

OBJECTIVE: Surgical approaches to ambient cistern lesions are complex. We investigated the microanatomy of the transtemporal-transchoroidal fissure approach to the ambient cistern with emphasis on exposure of the posterior cerebral artery. METHODS: Dissections were performed bilaterally in five silicone-injected cadaveric heads. Critical anatomic distances, specifically with reference to the P2 segment of posterior cerebral artery in relation to the inferior choroidal point and P2-P3 junction, were measured with digital calipers. Other landmarks (temporal lobe tip, points from the temporal base to the choroidal fissure) were included for quantitative analysis. RESULTS: The transtemporal-transchoroidal fissure approach provided adequate exposure of the ambient cistern, minimized temporal lobe retraction, and allowed assessment of regional microanatomy. The mean distance from the temporal base to the choroidal fissure measured 18.09 mm (range, 16.9-21.9 mm). The distances from the choroidal fissure to P2 varied at the coronal plane of the inferior choroidal point (mean, 6.96 mm; range, 3.6-12.0 mm) and the P2-P3 junction (mean, 6.02 mm; range, 4.3-6.9 mm), respectively. CONCLUSION: The transtemporal-transchoroidal fissure approach provides a corridor to the ambient cistern and P2-P3 junction while minimizing temporal lobe retraction and avoiding interruption of temporal lobe venous drainage. Because of widely variable vascular anatomy, access to posterior cerebral artery lesions using this approach requires preoperative imaging to identify the specific location of the P2-P3 junction.

Arachnoid↗
PubMedDate not supplied

[Digital cineradiology in the diagnosis and surgical treatment of pharyngo-oesophageal junction motor disorders].

The aim of the study was to report our experience with the use of radiology in functional disorders of the cricopharyngeal muscle and their surgical therapy using digital cineradiology. Five-hundred and seventy dysphagic patients underwent dynamic study of the oral and pharyngeal phases of swallowing (Videofluoroscopic Swallowing Study, VFSS). A motor disorder of the cricopharyngeal muscle was diagnosed by videofluorography in 19 patients: the disorder was mild in 8, moderate in 7 and severe in 4. Two of these underwent cricopharyngeal myotomy, with an improvement in their dysphagia and swallowing mechanisms. VFSS provides a morphological and functional view of the aero-digestive tracts: this is essential in the diagnosis of cricopharyngeal dysfunction and is capable of revealing the related laryngeal penetration and tracheal aspiration. VFSS must always include an oesophageal phase study because of the known clinical and physico-pathological correlations between the gastro-oesophageal junction and the upper oesophageal sphincter. On the basis of our experience we believe that VFSS could be used as a primary investigation, followed by motility studies, and that it may be a useful complementary procedure both in the diagnosis of pharyngo-oesophageal junction motor disorders and with a view to surgical indications.

Aged↗
PubMed1994

Modifications in myotendinous junction surface morphology in dystrophin-deficient mouse muscle.

Single muscle fibers from mdx mouse muscle, which is deficient in dystrophin, and control mouse muscle, containing dystrophin, were compared by scanning electron microscopy. In particular, comparisons were made of the surface morphology at myotendinous junctions and costameres, sites at the muscle cell surface that are enriched in dystrophin and where force is transmitted across the cell membrane. Muscle fibers from 4- and 6-week-old controls display nearly uniform surface morphology characterized by numerous digit-like processes at the myotendinous junction and nonjunctional surface membrane possessing distinct grooves at sites corresponding to underlying costameres. Mdx fibers at this stage showed blunted myotendinous junctions with few digit-like processes, infrequent indistinct costameric markings, and holes in the cell membrane. Cells from peak regenerating mdx muscle (6 weeks) showed surface morphology similar to 4-week mdx fibers, although the proportion of fibers displaying extensive structural defects was reduced at 6 weeks. Completely regenerated mdx fibers (23 weeks) were indistinguishable from fibers of 6-week-old mdx mice. In control mice, only approximately 6% of the fibers examined from 4- or 6-week-old mice showed any of the structural defects characteristic of the majority of mdx fibers. However, fibers from 23-week-old control mice displayed an increased frequency of cells with poorly defined junctional processes and surface striations. These findings indicate that the fibers displaying extensive disruption of surface features, which are most commonly observed in 4-week mdx mice at peak necrosis, are necrotic fibers. Specific defects, such as the reduction in myotendinous junction folding, loss of costameres, and increased occurrence of membrane holes, are observed in the majority of mdx fibers at all ages. Thus, these defects are more directly attributable to dystrophin's absence because their frequency of occurrence is independent of the stage of necrosis and regeneration.

Animals↗
PubMed2000

Objective assessment of post-traumatic nerve repairs and neuromas.

The assessment of a nerve repair usually focuses on the level of sensory and motor recovery distal to the site of the repair. However, the development of a painful neuroma or nerve junction, particularly in a digit, can be just as disabling to the patient as an area of anaesthesia. An instrument has been developed to assess objectively the severity of neuroma formation at nerve-repair sites by measuring the threshold percussive force required to elicit a Tinel's sign using standard weights dropped from a uniform height in a tube.

Diagnostic Techniques, Neurological↗
PubMed1982

Small changes in free energy assignments for unpaired bases do not affect predicted secondary structures in single stranded RNA.

We present extensive calculations of the secondary structure of mRNA which point to its insensitivity to small changes in the free energy assignments of single stranded regions. Truncating the free energies of hairpin loops, bulges, internal loops and multibranched junctions to two significant digits yields structures nearly identical to those generated using three digit values. The results show that one can safely use truncated values in RNA folding calculations. The implementation of these results enabled us to carry out secondary structure calculations on 2600 nucleotides in a single computer run.

Base Composition↗
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↗
PubMed1981

Histological study of the ependyma of the hypothalamic third ventricle in the water snake Natrix maura (L).

The ependyma of the hypothalamic third ventricle of Natrix maura (L) has been investigated by light microscopy employing Nissl and Golgi stains. Electron microscopy was also used. Brains were fixed by intraventricular perfusion and embedded in paraffin, celloidin and Spurr resin. Light-microscopically the ependyma appears as a simple layer epithelium with round or enlarged nuclei. It sometimes shows basal processes extending into the subependymal tissue. These processes can be clearly seen in Richardson stained semithin sections. They often contact the subependymal capillaries. Electronmicroscopically, tanycytes contacting capillaries show numerous microvilli and few cilia as well as pinocytotic vesicles at their apical surfaces. There are zonulae adherentes and probably gap junctions as well as digitations and desmosomes. In the apical cytoplasm there are mainly mitochondria, endoplasmic reticulum and Golgi apparatus. Near the nuclei and specially in the basal process there are many microtubules. The tanycytes contact the capillaries by an end foot containing mitochondria and pinocytotic vesicles, which are also observed in the endothelian cytoplasm. These structures lead us to think, like several other authors, that the tanycytes of Natrix maura (L) may serve as a linkage between CSF and the capillaries and that they possess the morphological features which are necessary to effect intracellular transportation.

Animals↗
PubMed1982

A preparation for studying dystrophic avian muscle and neuromuscular junctions.

The extensor of the second digit of the chicken wing (EDII) is a small, fast-twitch muscle susceptible to chicken muscular dystrophy and well suited for correlated studies of the morphology and physiology of identified nerve and muscle fibers. In cross section, the dystrophic EDII shows morphological abnormalities common to other well-studied dystrophic chicken muscles. However, in contrast to other dystrophic chicken muscles, living endplates can be viewed in the EDII, facilitating electrophysiological studies. A survey of electrophysiological properties of the EDII muscle in birds 5-16 weeks ex ovo revealed that compared to normal preparations, the dystrophic preparations had: (1) lower resting potentials, (2) lower miniature endplate potential frequency, (3) abortive nerve-evoked action potentials recorded extrajunctionally, and (4) multiple muscle fiber action potentials to a single depolarizing current pulse.

Action Potentials↗
PubMedDate not supplied

Three-dimensional computer reconstruction of the distribution of neuromuscular junctions in the thyroarytenoid muscle.

Microinjections of botulinum toxin have recently been shown to be effective in the treatment of strabismus, and it has also been suggested that microinjections of this myoneural blocking agent might be of value in the treatment of spastic dysphonia. The success of such a microinjection technique would rely on a precise knowledge of the distribution of myoneural junctions in the thyroarytenoid muscle. In view of this potential application as well as the need for such information in reinnervation procedures, we have used computer graphics to reconstruct the three-dimensional distribution of motor end-plates in the thyroarytenoid muscle. Three cat and one human (fresh autopsy specimen) larynges were frozen and sectioned on a cryostat. Serial sections were then processed for the histochemical localization of acetylcholinesterase activity to demarcate the neuromuscular junctions. An X-Y digitizer was used to reference the position of the motor end-plates in each serial section, and the three-dimensional distribution of the neuromuscular junctions was reconstructed on a computer graphics terminal. The results are discussed in regard to their applicability to clinical treatment of spastic dysphonia and other disorders of phonation.

Animals↗
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↗
PubMed1998

Reliability of linear alveolar bone loss measurements of mandibular posterior teeth from digitized bitewing radiographs.

Observer reliability in performing linear measurements between the cementoenamel junction and alveolar crest was determined for mandibular posterior teeth from digitized clinical bitewing radiographs acquired during recall examinations. 6 measurements (corresponding to traditional probing measurements) were made per tooth by 3 observers. Mesial and distal measurements made to the most coronal aspects of the alveolar crest were the most reliable and least biased. As was anticipated, intra-observer reliability was better than inter-observer reliability although the 3 observers of our study were able to detect a significant mean change (0.1 mm, p<0.0001) in alveolar bone height over a 1-year period for 10 patients. For our most reliable and unbiased measurements (mesial measurements to the alveolar crest), a change of 0.54 mm (90th percentile) would be required to indicate change at a site from one time to the next. Based on the reliability of our digital radiographic measurements, with the alpha error rate set at 0.05 and beta at 0.20, a difference in alveolar bone height of 0.3 mm could be detected with a patient sample size of between 13 (best case) and 54 (worst case).

Alveolar Bone Loss↗
PubMed1998

Connexin43 gap junctions in normal, regenerating, and cultured mouse bone marrow and in human leukemias: their possible involvement in blood formation.

Communicating channels called gap junctions are thought to play a ubiquitous part in cell growth and development. Based on earlier work, we have recently found functional evidence of their presence in human and mouse bone marrow. In this study we studied the cell-type association of the gap junction channel-forming protein, connexin, in mouse and human bone marrow under different physiological and pathological conditions and tested the pathway of communication in bone marrow cultures. For high-resolution antigen demonstration we took advantage of semi-thin resin sections, antigen retrieval methods, immunofluorescence, and confocal laser scanning microscopy. Connexin43 (Cx43) and its mRNA were consistently expressed in human and rodent marrow. Cx37 was found only in the arteriolar endothelium, but neither Cx32 nor -26 were expressed. In tissue sections, the immunostained junctions appeared as dots, which were digitally measured and counted. Their average size was 0.40 mm in human and 0.49 mm in mice marrow. There were at least twice as many gap junctions in the femoral midshaft of 6-week-old mice (1.75 x 10(5)/mm3) as in those older than 12 weeks (0.89 x 10(5)/mm3). Most Cx43 was associated with collagen III+ endosteal and adventitial stromal cells and with megakaryocytes. Elsewhere, they were few and randomly distributed between all kinds of hematopoietic cells. In the femoral epiphysis of juvenile mice, stromal cell processes full of Cx43 enmeshed three to six layers of hematopoietic cells near the endosteum. The same pattern was seen in the midshaft of regenerating mouse marrow 3 to 5 days after cytotoxic treatment with 5-fluorouracil. Functional tests in cultures showed the transfer of small fluorescent dyes, Lucifer Yellow and 2',7'-bis-(2-carboxyethyl)-5, 6-carboxyfluorescein, between stromal cells and in rare cases between stromal and hematopoietic cells too. The stromal cells were densely packed with Cx43 and we found aggregates of connexon particles in their membrane replicas. In normocellular human bone marrow, gap junctions were as rare as in adult mouse and similarly distributed, except that they were also on adipocytic membranes. In a few leukemic samples, characterized by an increased stromal/hematopoietic cell ratio, there were two- to fourfold more Cx43 (2.8 x 10(5) to 3.9 x 10(5)/mm3) than in the normal (1.0 x 10(5) to 1.2 x 10(5)/mm3). The cases included a hypoplastic acute lymphoblastic leukemia, an acute myeloid leukemia (French-American-British classification M4-5), a case of myelodysplastic syndrome with elevated number of megakaryocytes, and a CD34+ acute hemoblastosis, probably acute myeloid leukemia (French-American-British classification M7). Taken together, our results indicate that direct cell-cell communication may be involved in hematopoiesis, ie, in developmentally active epiphyseal bone marrow and when there is a demand for progenitors in regeneration. However, gap junctions may not play as important a role in resting adult hematopoiesis and in leukemias.

Adolescent↗