[Laser endoscopy: diagnosis and therapy. 3. Development of the contact optic fiber probe].
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Animals↗
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Results for “fiber development”
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[Laser endoscopy: diagnosis and therapy. 4. Development of the lateral radiation fiber probe].
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Endoscopes↗
A step-zoom probe for laser endophotocoagulation: I. Design.
A step-zoom probe for laser endophotocoagulation of the eye has been developed, using fiber optics and a gradient index (GRIN) rod lens. It provides the operator with five or more focused spots ranging in size from 50 to 500 microns, and the spot size on the target is independent of the media filling the vitreous cavity, i.e., fluid or air. Each spot is located at the waist of the beam and therefore can be easily placed on the target, reducing the potential for overtreatment. A prototype model is currently undergoing animal testing.
Animals↗
[Immunochemical markers of embryonic lens differentiation in Rana temporaria. II. Immunohistochemical analysis of the manifestation and localization of individual classes of lens proteins].
Individual lens proteins were studied during development of Rana temporaria. Antisera to alpha-, beta-crystallins of chicks and gamma-crystallins of Rana ridibunda were used as immunochemical markers. Besides the main crystallins, a new antigen was found in the R. temporaria lens tentatively called alphabeta-crystallin. It appears to be characteristic only for the amphibian lens. Using the indirect method of fluorescent antibodies, it was shown that all the antigens under study appeared in the lens of the R. temporaria tadpoles within 1--2 days (at 20 degrees). The crystallins are found initially only in the developing lens fibers and later in the lens epithelium. It was established that the lens epithelium contained gamma-crystallins which appeared somewhat earlier than alpha- and beta-crystallins, but simultaneously with alphabeta-crystallin.
Animals↗
[Ultrastructure of mesenteric lymphatic postcapillaries of the small intestine of the human fetus].
Lymphatic vessels of the small intestine mesentery have been investigated in 36 human fetuses 3-6-month-old. Lymphatic postcapillaries are the predominant link in the lymphomicrocirculatory bed studied. They differ from the capillaries only by presence of valves. Intersegmentary valves and velves at the places where the lymphatic capillaries get into the postcapillaries are described; they are situated along the whole length of the postcapillary. Both types of the valves can be uni- and besinusoid, and according to the number of endotheliocytes, covering the sinuses, uni- and multicellular. Cells of fibroblastic line and developing collagenous fibers are inevitable structural components and situate in their base. Ultrastructural peculiarities of the lymphatic postcapillary wall are described. Structural mechanisms responsible for dilatation and narrowing of the vascular lumen (formation of the pulse wave) are discussed. The data obtained support the conception successively elaborated by V. V. Kuprianov on the lymphatic postcapillary as an inevitable link of the lymphomicrocirculatory bed.
Humans↗
[Myasthenia gravis. New results on etiology, diagnosis and therapy].
Myasthenia gravis is discussed with reference to recent immunologic findings, improvements in diagnostic procedure, and therapy. Myasthenic reactions can be produced in animals by injection of receptor proteins. In addition, the injection of thymopoietin causes neuromuscular block. The majority of patients with myasthenia gravis have antibodies against acetylcholine receptors, and there is a markedly reduced number of bungarotoxin binding receptors at the endplates. Further, recent immunologic findings indicate that genetic factors may be involved in the etiology of myasthenia gravis. The recently developed single fiber electromyography is useful in the diagnosis of myasthenia gravis. New statistics demonstrate the value of thymectomy in the treatment of myasthenia gravis. Good results have been reported following treatment with corticosteroids and azathioprine.
Adrenal Cortex Hormones↗
[Development and use of synthetic fibers in the hospital].
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Bedding and Linens↗
[Substance P].
Substance P (SP) is a polypeptide formed by 11 amino acids of the tachykinin family. SP is found in the peripheral nervous system, particularly in small diameter myelinated and non myelinated afferent fibers. It is concentrated at both proximal and distal ends of sensory neurones to the skin, mucous membranes, viscera and vessels throughout the body. In the central nervous system SP is concentrated in the basal ganglia (striatonigral system), the habenulo-interpeduncular system, the brain stem (particularly in afferent spinal tract neurones) and the hypothalamus. Neurones containing SP may also contain other neurotransmitters. Criteria for identification of SP are similar to those applying to other neuromediators except for duration of action, which is comparatively greatly prolonged for SP. SP exerts complex synaptic effects, both pre- and post-synaptic, and usually acts as an activating factor. Its physiological role is unknown but it could intervene in peripheral nociceptive processes by its peripheral (oedema and plasma extravasation) and central (excitation of dorsal horn sensory neurones and facilitation of medullary reflexes by depolarization of motor neurones) effects; in central regulation of nociceptive impulses (analgesic effect); in regulation of some vegetative functions (glandular secretion, digestive and vasomotor motility, hypothalamic functions); in certain motor regulatory actions as suggested by the large amounts of SP in the striatonigral tract and the motor effects induced by injection of SP into the substantia nigra; in control of some learning processes; in control of growth of some central nerve fibers during development.
Animals↗
[Experimental study of a biological micro-arterial prosthesis].
An arterial prosthesis prepared from human placental arteries, diameter 1.0 mm, length 20 mm, was evaluated after implantation into the infrarenal region of the aorta of the rat. The permeability rate after one year (70%) compares favorably with results after fresh arterial autografts. Histology showed that the prosthesis acted as a matrix colonizable by the tissues of the recipient. The internal surface of the tube was covered by a tissular layer in which fibrillary elements suggestive of elastic fibers were developing.
Animals↗
[Role of potassium permeability in action potential development in denervated frog muscle fibers].
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Action Potentials↗
Interaction of Escherichia coli cytotoxic necrotizing factor type 1 (CNF1) with cultured cells.
The cytotoxic necrotizing factor type 1 (CNF1) from E. coli causes necrosis in rabbit skin and multinucleation in cultured cells. Cells exposed to CNF1 were characterized by changes in actin organization, mainly consisting in the presence of well-developed stress fibers and membrane ruffles. The interaction of CNF1 with the cell cytoskeleton probably promotes the cell spreading and interferes with the cytokinesis, leading to the formation of giant multinucleated cells.
Actins↗
Fyn expression during early neurogenesis in mouse embryos.
Fyn is a member of the Src family of tyrosine kinases which are thought to play important roles in cell to cell interactions during morphogenesis. The developmental profile of Fyn expression was examined using mutant mice in which lacZ gene was introduced into this locus. The expression was characteristic in the neural system. Though at low levels, it was detected in the headfold at embryonic day (E) 7.5 and in the luminal surface of neuroectoderm along the entire neural groove at E8.5. The expression appeared regional in rhombomeres at E8.5 and E9.5. Consistent expression was also found at a low level in the notochord. The expression was high in later stages of the neural tube which consists of three layers; it was in the marginal layer but not in the germinal layer. High expression was also found in developing dorsal root filaments of neural crest origin. Non-expression in dividing neuroepithelial cells and expression in developing neural fibers appeared ubiquitous features of Fyn expression throughout the entire brain.
Animals↗
[Quantifying intestino-esophageal reflux with a fiberoptic bilirubin detection probe].
Currently available methods to assess reflux of duodenal contents into the esophagus are cumbersome, unphysiologic, and inaccurate. The role of intestino-esophageal reflux has therefore been controversial. We assessed intestino-esophageal reflux using a new system which allows prolonged intraesophageal measurement of bilirubin, the major pigment of bile. Measurements were made with a newly developed fiber-optic sensor electrode connected to a portable data processing unit (BILITEC 2000, Synectics Medical Inc., Sweden). Light absorption was measured at the absorption peak of bilirubin and a reference point. Studies were performed in 9 subjects without esophagitis, 9 subjects with esophagitis and primary reflux disease and 7 subjects with erosive esophagitis after a total or subtotal gastrectomy. The fiberoptic electrode was placed 5 cm above the lower esophageal sphincter. In vitro studies showed linear correlations between absorbance measurements obtained with the BILITEC-unit and known bilirubin and bile acid concentrations, respectively (p < 0.01). Compared to both other groups, light absorption was markedly increased in the subjects who had esophagitis after a total or subtotal gastrectomy (p < 0.05) indicating severe biliary reflux. An increase in bilirubin absorption occurred particularly during the post-prandial and supine periodes (p < 0.01). A Roux-en-Y biliary diversion procedure completely abolished bile reflux in 2 of these patients. These data indicate that ambulatory 24-hour fiberoptic measurement of bilirubin in the esophagus is feasible and allows quantitation of intestino-esophageal reflux. Intestino-esophageal reflux occurs particularly during the postprandial period and the early morning hours in patients who had a previous subtotal or total gastrectomy.
Adult↗
[Effect of mutant genes on crystallin synthesis in the forming mouse lens. 1. Dominant gene cataract-Fr].
The beginning of synthesis, localization and content of crystallins were studied in the developing lenses of 9--13 and 15 days old embryos of CatFr/CatFr and +/+ mice by means of immunofluorescence and polyacrilamide gel electrophoresis. The mutant gene CatFr was shown not to affect the crystallin synthesis. Alpha-crystallins are first to be synthesized in the cytoplasm of cells of the proximal part of the lens vesicle (10 days of development). Gamma-crystallins are detected for the first time in the lens of 11 days old embryos in the cytoplasm of developing lens fibers which lost their ability to divide. The differences in the time of synthesis of alpha- and gamma-crystallins are, possibly, related to their different role in the process of lens fiber differentiation.
Animals↗
Synthesis of lens capsule in long-term culture of human lens epithelial cells.
PURPOSE: This study examined the extent to which human lens epithelial (HLE) cells in tissue culture retain the potential for differentiation, expression of lens-specific marker proteins, and the synthesis of lens capsule, the major characteristics of lens epithelium in vivo. METHODS: Primary cultures of HLE cells were maintained for up to 450 days. Transmission and immunoelectron microscopy were used to study the thickness of the synthesized capsule and the formation of type IV collagen and laminin, two major protein components of the basement membrane of lens capsule in vivo. RESULTS: In a long-term HLE culture system, without subcloning, lens fiber differentiation and capsular synthesis were maintained over a period of 450 days. In these cultures, the cell sheet showed three distinct zones: (1) a central zone with tight monolayer; (2) a mild peripheral zone with irregularly aggregated multilayer; and (3) a peripheral zone with loose monolayer. The basement membrane-like material was synthesized in the central zone and lentoids, which serve as a model for fiber differentiation, developed primarily in the mid peripheral zone. No capsular material or lentoids were observed in the peripheral zone. The capsule-like material was 2 to 2.5 microns thick and showed the presence of type IV collagen and laminin, as detected by antibody reaction. CONCLUSION: This study demonstrates for the first time that HLE cells in long-term cultures synthesize a continuous sheet of capsule-like material. The findings also suggest that reformation of a tight cell-to-cell relationship or generation of high cell density similar to that found in vivo may be an important factor for the synthesis of lens capsule.
Basement Membrane↗
Double crush syndrome in lower extremities.
Retrospective analysis of results of electromyography and nerve conduction velocity was performed in 169 patients with lower back pain, mostly caused by trauma. A total 289 peroneal, 280 posterior tibial and 301 sural nerves were included in statistical analysis. Peripheral entrapment of nerves (tarsal tunnel syndrome and anterior tarsal tunnel syndrome) were found in 5.3% of patients, signs of acute or chronic partial muscle denervation of corresponding muscles of lower extremities in 21.8% of patients, and abnormally prolonged F-wave latency in 12.5% of patients. Combined partial denervation and abnormally prolonged F-wave latency were found in 6.2% of patients, combined partial denervation and peripheral entrapment of nerves in 4.4% of patients, combined abnormally prolonged F-wave latency and peripheral entrapment of nerves in 2.4% of patients and combined partial denervation, abnormally prolonged F-wave latency and peripheral entrapment of nerves in 3.5% of patients. Statistical analysis of these data showed significantly higher than random overlap of peripheral entrapment syndromes and signs of proximal nerve damage of the corresponding nerves (partial muscle denervation or abnormalities of F-wave). This higher than random coincidence of the two conditions strongly suggests cause-and-effect relationship of damage of the proximal stretch of motor nerve fibers and development of peripheral entrapment syndromes in the same nerves rather than a random coincidence of two independent pathologies. Appreciation of this causal relationship is important in the development of comprehensive approach to treatment of peripheral entrapment syndromes. In appropriate cases, simultaneous treatment of the lower back problem should be considered as well.
Adolescent↗
Acetone excretion into urine of workers exposed to acetone in acetate fiber plants.
To develop a proper protocol for biological exposure monitoring of acetone, we evaluated whether exposure to acetone on the previous day affects the biological monitoring value at the end of a work day. One hundred and ten male workers exposed to acetone in three acetate fiber manufacturing plants were monitored using a liquid passive sampler on two consecutive working days after 2 days without exposure. Urine samples were collected at the start of the workshift and the end of the shift on both days for each subject. For ten exposed workers urine samples were collected approximately every 2 h during and after the first working day until the following morning. Acetone concentrations in urine (Cu) at the start of the first working day were 1.3 +/- 2.4 (range: ND-14.1) mg/l in nonexposed workers and 2.4 +/- 5.6 (range: ND-40.3) mg/l in exposed workers. The urinary acetone concentration at the beginning of the second working day indicated that urinary levels of acetone do not decline to background level by the following morning when exposure concentration exceeds 300 ppm. However, linear regression analysis demonstrated that the relationship between environmental exposure level and urine level was similar on the 1st day and the 2nd day. Thus, although urine acetone levels did not return completely to baseline after high exposures, under the present exposure levels the exposure on the previous day did not significantly affect urinary acetone at the end of the workshift of the next day.
Acetone↗
Morphology and position of growth cones in the developing Xenopus spinal cord.
Axonal growth cones in longitudinal fiber tracts of the developing spinal cord of Xenopus were examined using electron microscopy. Fiber tracts of the spinal cord develop by the ingrowth of fibers, into pre-existing longitudinally oriented spaces between adjacent neuroepithelial cells of the neural tube. Growth cones seen among the neurites of the tracts were identified by their generally larger size (1.2 X 4.5 micrometer), bulbous and irregular outlines, and cytoplasmic components. Overall cytoplasmic density was usually less than that of surrounding neuroepithelial cells and axons. They contained few organelles, among them assorted clear and densecored vesicles, agranular reticulum, and occasional mitochondria and autographic vacuoles. Microtubules were rarely present. Growth cones appeared to conform in outline to the space which they occupied. Smaller extensions which resembled the filopodia described by others insinuated themselves among other elements of the fiber fascicles. The filopodia contained a fine granular or filamentous feltwork. Growth cones consistently appeared at the interface of other axons in the fascicle and the peripheral neuroepithelial endfeet. In longitudinal sections of fascicles containing more than one growth cone, the growth cones were layered in a pattern suggesting that new cones are added by pushing between the next youngest fibers and the peripheral neuroepithelial processes of the cord. The possible significance of this finding in the achievement of order in the spinal tracts is discussed.
Animals↗