Biomedical subjects
Publications and source records attributed to D Lim.
Microprobe analysis was performed at the cellular and subcellular levels of type I and type II vestibular hair cells. In principle the same types of elemental histograms were found in the two types of hair cells studied. High concentrations of Cl and K were detected in stereocilia, whereas calcium was found when analyzing stereocilia and the supranuclear cytoplasm.
A previously healthy 6-year-old boy who presented with meningococcal meningitis responded favorably to ampicillin, but suffered two and possibly three repeat attacks in the ensuing month. No abnormality of the otolarynx, skin, or neuroskeleton was found. The infecting strain, Neisseria meningitidis, Group Y, Type IV, was sensitive to the therapeutic agents used, and antibiotic levels were adequate. Serum bactericidal antibody titers against autologous meningococci were high. Serum complement hemolytic bactericidal activities, however, were entirely lacking, and this was attributable to a complete deficiency of C6. Measurements of the remaining complement components, C-dependent chemotaxis and opsonization, neutrophil function, specific immunity, and the coagulation system, were normal. The parents had half-normal C6 levels. Recurrence of meningitis in this patient supports the concept that complement plays a role in resistance to certain microorganisms and emphasizes the need for complete evaluation of the complement system in individuals with unexplained repeated infections.
From two families, one with Clr deficiency and the other with C6 deficiency, evidence was obtained suggesting genetic independence between the transmission of a 50% deficit in the functional activity of these two complement components and the inheritance of the HL--A system, the ABO system, and the sex of individuals.
Human external auditory canal skin, with a special emphasis on the secretory system, was studied by light, transmission electron and scanning electron microscopy. Two types of secretory glands were observed: modified apocrine (ceruminous) and sebaceous. The sebaceous secretory cellere homogeneous; on the other hand, modified apocrine secretory cells contained heterogeneous secretory granules. They were ither dark granules or light granules. Evidence to support both the apocrine as well as the eccrine mode of secretion was noted in the modified apocrine gland. This finding is partly in agreement with early reports based on light microscopy with suggested only an apocrine mode and data based on transmission electron microscopy which showed only the eccrine mode. Significance of the secretion by the external ear canal and its role in a local immune defense system is discussed.
The human middle ear corpuscles originally described by von Troeltsch are examined by means of light microscopy in 124 subjects, and electron microscopy in 27 subjects. While the corpuscles are not observed in all 19 individuals under age six, and in all 20 adults who had a history of suppurative otitis media, an average of six corpuscles per temporal bone is found in 98 percent of 83 adult subjects who had no history of middle ear disease. Two-thirds of the corpuscles are located in the mastoid, and the remainder in the middle ear. Often, they become bifurcated or trifurcated. Although light microscopy shows that the corpuscle is formed by lamellar capsules and a central core resembling pacinian corpuscles, electron microscopic study failed to confirm that this structure is a typical pacinian corpuscle. Subsequently, possible physiological significance of this corpuscle is discussed.
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Immunological phenomena occurring in the mucosa of the middle ear and Eustachian tube were investigated following tubal obstruction in squirrel monkeys which produced middle ear effusions. Although there are many variations among specimens, in general all classes of immunoglobulin producing plasma cells have shown an increase in number and/or an increase in intensity of fluorescence. IgG and IgA-producing plasma cells were more prominent than those producing other immunoglobulins. These findings support the concept that the middle ear and Eustachian tube in monkeys as in humans is protected by an immunodefense system.
This study demonstrates the mechanism of sensory hair fusion and its relationship to glycocalyx on the hair cells in the vestibular epithelia of gentamicin-treated guinea pigs, using a ruthenium red staining technique. 0.1 ml of a solution containing 50 mg gentamicin sulphate per 1 ml was injected once into the middle ear. After 7 days, various stages of sensory hair degeneration were observed. The glycocalyx was clearly visualized by ruthenium red. The gentamicin-induced hair damage started with a local decrease in or loss of glycocalyx from neighbouring sensory hairs, followed by formation of local attachment areas of membrane sensory hairs. These findings suggest that the glycocalyx of the sensory cell may play an important role in separating the cilia as well as maintaining the organization of the bundle. Therefore, the decrease in or loss of glycocalyx from the hair bundle of sensory cells affected by gentamicin, either directly or secondarily, can be considered as closely related to the fusion of the sensory hairs.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.