PubMed Health⌕ Search

Biomedical subjects

M C Schultz

Publications and source records attributed to M C Schultz.

At least 37 records · Page 2Linked to original sources
PubMed1989

Ultrastructural study of the coiled body and a new inclusion, the "mykaryon," in the nucleus of the adult rat Sertoli cell.

Random and serial thin sections of the nucleus in adult rat Sertoli cells were examined by electron microscopy. Besides the previously reported nucleoli and heterochromatin masses, the nuclei contain a coiled body and a new structure, the "mykaryon." The coiled body is 835 nm in maximum diameter. It is composed of distinct elements referred to as "coils." They are 32 nm wide on average and resemble the nucleolar pars fibrosa in their intense staining with heavy metal salts and their composition of narrow filaments. The coiled body is often close to a nucleolus, though no direct contact is established, and it sometimes exists at a distance from the nucleolus. The mykaryon is spherical, 460 nm in maximum diameter, and composed of a tridimensional network of 7-26 nm-wide electron-opaque "cords" separated by slightly thinner spaces. It has not been observed in the vicinity of a nucleolus. A literature survey showed no previous mention of a structure similar to the mykaryon. The coiled body and the mykaryon are interpreted as normal constituents of the Sertoli nucleus in the adult rat.

Animals↗
PubMed1989

Analytic study of the Tadoma method: effects of hand position on segmental speech perception.

In the Tadoma method of communication, deaf-blind individuals receive speech by placing a hand on the face and neck of the talker and monitoring actions associated with speech production. Previous research has documented the speech perception, speech production, and linguistic abilities of highly experienced users of the Tadoma method. The current study was performed to gain further insight into the cues involved in the perception of speech segments through Tadoma. Small-set segmental identification experiments were conducted in which the subjects' access to various types of articulatory information was systematically varied by imposing limitations on the contact of the hand with the face. Results obtained on 3 deaf-blind, highly experienced users of Tadoma were examined in terms of percent-correct scores, information transfer, and reception of speech features for each of sixteen experimental conditions. The results were generally consistent with expectations based on the speech cues assumed to be available in the various hand positions.

Adult↗
PubMed1989

The Xenopus ribosomal gene enhancers bind an essential polymerase I transcription factor, xUBF.

We purified xUBF on the basis of its ability to specifically bind the enhancer elements of the Xenopus laevis rRNA genes. xUBF also binds to both upstream and downstream regions of the X. laevis ribosomal gene promoter and is essential for polymerase I transcription. Unexpectedly, xUBF binds to both upstream and downstream regions of the human ribosomal gene promoter, producing footprints that are indistinguishable from the footprints produced by hUBF, a previously described polymerase I transcription factor isolated from human cells. Despite extensive sequence divergence of vertebrate polymerase I promoters, these data suggest an evolutionary conservation of the primary DNA-protein interaction.

Animals↗
PubMed1985

Research on the Tadoma method of speech communication.

In Tadoma, speech is received by placing a hand on the talker's face and monitoring actions associated with speech production. Our initial research has documented the speech perception, speech production, and linguistic abilities of deaf-blind individuals highly trained in Tadoma. This research has demonstrated that good speech reception can be achieved through the tactile sense: Performance is roughly equivalent to that of normals listening in noise or babble with a signal-to-noise ratio in the range 0-6 dB. It appears that the principal cues employed are lip movement, jaw movement, oral airflow, and laryngeal vibration, and that the errors which occur are caused primarily by inadequate information on tongue position. Our current research includes (1) learning of Tadoma by normal subjects with simulated deafness and blindness, (2) augmenting Tadoma with a supplemental tactile display of tongue position, and (3) developing a synthetic Tadoma system in which signals recorded from a talker's face are used to drive an artificial face. This research is expected to increase our understanding of Tadoma and its relation to other tactile communication methods, show that performance obtained through Tadoma does not represent the ultimate limits of the tactile sense, and provide a research tool for studying transformations of Tadoma.

Adult↗
PubMed1984

Structure, development, and cytochemical properties of the nucleolus-associated "round body" in rat spermatocytes and early spermatids.

The "round body," a spherical structure typically associated with a nucleolus in male germ cells of the rat, has been examined in the electron microscope using routine and cytochemical methods to determine its structure, composition, and mode of development. Cytochemical analysis indicates that the round body includes neither nucleic acid nor lipid, but is composed of nonhistone protein which appears in the form of 1.6-nm-wide fibrils. Development begins in late leptotene, when a single round body appears in each spermatocyte as an irregular spheroid located along the inner surface of the nuclear envelope. During subsequent stages of the meiotic prophase, the round body leaves the nuclear envelope, becomes a regular sphere, and gradually enlarges from a diameter of 0.4 micron in leptotene to 1.6 micron in diplotene. Concurrently, lacunae appear within its substance and enlarge. At each maturation division, the amount of round-body material is decreased by about half, presumably because the constituent proteins are dissociated at metaphase, distributed between the two daughter cells at telophase, and reconstituted into half-sized round bodies. As spermiogenesis proceeds, the round body shrinks gradually and disappears at step 8. Soon after its appearance at leptotene, the round body becomes associated with and is surrounded by the pars granulosa of one of the nucleoli. Moreover, 3H-uridine incorporation into nucleolar RNA is high as long as the size of the round body increases, but is low or absent when it decreases. It is possible, therefore, that the round body exerts some control on nucleolar activity in meiotic cells.

Animals↗
PubMed1984

Auditory processing tests for children: normative and clinical results on the SSW test.

Staggered Spondaic Word (SSW) test results were studied in 93 normally achieving children and 97 children referred to a learning disabilities clinic. All subjects were 8-11 years of age. The SSW test was found to differentiate between the normally achieving children and those experiencing classroom learning difficulties. Further, it was found that the performance of the normally achieving group was generally better than current test norms would imply. This finding suggests the use of stricter criteria in determining when a child is at risk for central auditory processing difficulties. Results for children with classroom learning difficulties show a progression toward better performance with age, except for the Left-Competing condition. This makes it unclear whether one can or cannot expect some resolution of auditory processing difficulties by age 11.

Age Factors↗
PubMed1983

A correlated light and electron microscopic study of the structure and secretory activity of the accessory salivary glands of the marine gastropods, Conus flavidus and C. vexillum (neogastropoda, conacea).

The structure and secretory activity of the accessory salivary gland in two species of Conus were examined using routine and histochemical techniques of light, scanning and transmission electron microscopy. The composite layers of the accessory salivary gland of Conus are a luminal epithelium, fibromuscular layer, submuscular layer, and a capsule. In C. flavidus and C. vexillum, the luminal epithelium is formed by epitheliocytes and cytoplasmic processes extending from the secretory cells, whose perikarya form the submuscular layer. The processes carry secretory cell products (chiefly Golgi-derived glycoprotein) across the fibromuscular layer and terminate between epitheliocytes (at the bases of the secretory canaliculi) or beyond the surface of the epithelial cells. Conus vexillum is distinguished from C. flavidus by its high content of lipofuscin. Epitheliocytes are the only microvillated cells in the accessory salivary gland of Conus. In C. flavidus, epitheliocytes extrude secretory granules, various types of cytoplasmic blebs and clear vesicles by apocrine "pinching off." Clear vesicles are shed from the tips of microvilli. The luminal epithelial cells of C. vexillum similarly egest clear vesicles, but normally undergo additional holocrine secretion to release lipofuscin. The secretions of epitheliocytes appear to be major products of the accessory salivary gland: consideration of secretory activities by both epitheliocytes and secretory cells will therefore be necessary when directly investigating accessory salivary gland function in Conus.

Animals↗
PubMed1982

Analytic study of the Tadoma method: identification of consonants and vowels by an experienced Tadoma user.

Performance on identifying consonant and vowel stimuli through the Tadoma methods of speechreading was studied for a deaf-blind, experienced user of Tadoma. For a set of 24 consonants in CV syllables, performance averaged 55%. For a set of 15 vowels and diphthongs in CVC syllables, performance averaged 56%. Confusion matrices derived from the identification tests were analyzed for performance on a set of articulatory/phonological features, the results of the feature analysis for consonants indicated that the features voicing, lip rounding frication, and place were well-perceived; for vowels, and features lip rounding, tenseness, and vertical lip separation were well-perceived.

Adult↗
PubMed1977

Analytic study of the Tadoma method: background and preliminary results.

Certain deaf-blind persons have been taught, through the Tadoma method of speechreading, to use vibrotactile cues from the face and neck to understand speech. This paper reports the results of preliminary tests of the speechreading ability of one adult Tadoma user. The tests were of four major types: (1) discrimination of speech stimuli; (2) recognition of words in isolation and in sentences; (3) interpretation of prosodic and syntactic features in sentences; and (4) comprehension of written (Braille) and oral speech. Words in highly contextual environments were much better perceived than were words in low-context environments. Many of the word errors involved phonemic substitutions which shared articulatory features with the target phonemes, with a higher error rate for vowels than consonants. Relative to performance on word-recognition tests, performance on some of the discrimination tests was worse than expected. Perception of sentences appeared to be mildly sensitive to rate of talking and to speaker differences. Results of the tests on perception of prosodic and syntactic features, while inconclusive, indicate that many of the features tested were not used in interpreting sentences. On an English comprehension test, a higher score was obtained for items administered in Braille than through oral presentation.

Adult↗