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Biomedical subjects

C S Miller

Publications and source records attributed to C S Miller.

At least 91 records · Page 5Linked to original sources
PubMed1983

Alterations in cultured fibroblasts of sibs with an infantile form of a free (unbound) sialic acid storage disorder.

Cultured fibroblasts from two sibs with generalized hypertonia, hepatosplenomegaly, and psychomotor retardation within the first year of life were found to have unusual morphologic features. When examined by phase microscopy, the unstained and unfixed cells contained a large number of vacuolated structures whose gross appearance resembled that of a honeycomb in the cell cytoplasm. Electron microscopy studies, following fixation, showed the "honeycombing" to be the result of numerous, closely packed, cytoplasmic, membrane-bound vacuoles. In some of these structures the remains of fibrilogranular material could be detected. Biochemical analysis of crude sonicates of these cells revealed increased levels (4--7 x N) of an acid soluble component that reacted with thiobarbituric acid. Analysis of trimethylsilyl derivatives of this material by gas liquid chromatography and mass spectrometry showed it to be indistinguishable from sialic acid (N-acetylneuraminic acid). Quantitation of this material from the cells of one of the sibs after isolation on a Dowex column yielded 39.8 nmoles of free (unbound) sialic acid per mg protein whereas normal fibroblasts had 1--2 nmoles per mg. Bound sialic acid levels were at the upper limits of normal (24.8 versus 11--23 nmoles per mg protein). The concentration of cytidine monophosphate-sialic acid was normal. After incubation of the patient's fibroblasts with [3H]-N-acetylmannosamine for 72 h, there was a 7-fold increase (compared to normal fibroblasts) in the amount of radioactivity in free sialic acid present in the acid soluble fraction. The amount of labeled, bound sialic acid in the acid-insoluble pool, however, was the same in both patient and control fibroblasts.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1982

Nonuniform deficiency of hexosaminidase A in tissues and fluids of two unrelated individuals.

Serum samples from two unrelated, clinically normal individuals lacked detectable hexosaminidase A by heat inactivation and electrophoretic analysis. In contrast, 15 and 17% of the hexosaminidase in their leukocytes and 23 and 26% of the hexosaminidase of their cultured fibroblasts had the heat stability and electrophoretic properties of the A form of this enzyme. An in vitro measurement of fibroblasts GM2 ganglioside-beta-galactosaminidase was in the range expected for Tay-Sachs disease (TSD) heterozygotes (2.5 and 3.1 versus a normal mean of 3.7). In contrast, fibroblasts from a patient with TSD, analyzed in an identical fashion, contained no detectable activity. Ten days after addition of labeled GM2 ganglioside to the medium of the cultured fibroblasts, 43 and 59% of the radioactivity taken up by the cells of these patients remained as unhydrolyzed ganglioside as compared with 94% in TSD fibroblasts and 42% in control cells. An analysis of sphingolipid composition by high performance liquid chromatography although the endogenous level of GM2 was elevated in TSD fibroblasts (0.39 nmoles/mg protein) there was no increase in the cells of these patients (0 and 0.12 versus control of 0.17 nmoles/mg protein). Finally, the synthesis of hexosaminidase was examined by an electrophoretic analysis of immunoprecipitates of the enzyme precursors that had been radiolabeled by culturing fibroblasts in medium containing [3H]-leucine. These studies revealed a normal pattern of biosynthesis, processing and secretion of the alpha and beta chains. The ratio of the alpha chain to the beta chain, however, was in the range expected for TSD heterozygotes.

Adult↗
PubMed1982

Two clonal cell populations (mosaicism) in a 46,XY male with mucolipidosis II (I-cell disease)--an autosomal recessive disorder.

Cultured fibroblasts from a 46,XY male with an atypical form of mucolipidosis II (I-cell disease) had two distinct phenotypes. One population of these fibroblasts had the morphological and biochemical features characteristic of I-cell disease, while the remaining cells were indistinguishable from normal fibroblasts. Direct evidence that the patient was a mosaic, having two cell populations, was provided by the establishment of pure, stable clones of both wild type and I-cell fibroblasts from each of two biopsies obtained several months apart. Additionally, it was shown that the I-cell fibroblasts lacked UDP-N-acetylglucosamine:lysosomal enzyme N-acetylglucosaminylphosphotransferase while the morphologically normal cells contained levels of this enzyme just below or at the lower end of the normal range.

Cells, Cultured↗
PubMed1980

Exposure of pesticide applicators to arsenic acid.

The arsenic content of long-sleeved coveralls worn by ground rig drivers, pilots, and ground crew members averaged 430, 260 and 348 mg of arsenic, respectively after being worn during the normal pursuit of the application of arsenic acid as a desiccant on cotton in Texas and Oklahoma. The average arsenic content in breathing zone air for ground rig applicators was 7.8 microgram As/m3 during the application. The applicators coveralls received only about 0.1 to 50 ml of the applied spray. The results will aid in the determination of preliminary hazards of exposure to arsenic acid spray when the expected absorption percentage of arsenic from clothing and bare skin is determined at some future date.

Agricultural Workers' Diseases↗
PubMed1979

Characterization of neuraminidase activity of cultured human fibroblasts.

Investigations have been carried out to establish the enzymatic properties and specificities of the neuraminidase of cultured human fibroblasts. Homogenates of these cells cleaved the actylated derivative of neuraminic acid from fetuin, N-acetylneuraminyllactose and 2-(3' methoxyphenyl)-N-acetyl-alpha-neuraminic acid. Maximum activity occurred between pH 4.2 and 4.6 in sodium acetate buffer. The Km values were 3.6 . 10(-4) M, 3.0 . 10(-3) M and 1.1 . 10(-3) M, respectively, against fetuin, N-acetylneuraminyllactose and 2-(3'methoxyphenyl)-N-acetyl-alpha-neuraminic acid. Against the first two substrates, the rate of hydrolysis fell below the expected value as the cell homogenate was diluted with water or 10 mM NaCl. Dilution with 8 mg/ml bovine serum albumin prevented the deviation and yielded the expected linear decrease. After the first 2-h incubation, the rate of hydrolysis decreased from the initial linear rate. The enzyme(s) was partially or completely inactivated by sonication at 20 kHz, freeze-thaw treatment, incubation at 52 degrees C or storage for 48 h at -70 degrees C. Suspension of the fibroblasts in water for 10 min at room temperature, followed by homogenization with a tissue grinder, yielded preparations that were suitable for the assay of the neuraminidase activity.

Cells, Cultured↗
PubMed1979

Neuraminidase deficiency in the original patient with the Goldberg syndrome.

Homogenates of cultured skin fibroblasts from a non-ambulatory, 20-year-old male with cherry-red spots, corneal clouding, seizures, mental retardation, dysostosis multiplex, dwarfism, coarse facies and loss of vision, originally described by Goldberg et al. (1971), have diminished neuraminidase activity and an excess of neuraminic acid-rich compounds. Specifically, these cells have 2-17% normal neuraminidase when measured with 2-(3' methoxyphenyl)-N-acetyl-alpha-neuraminic acid, N-acetyl-neuramin-lactose and fetuin. Activities of 12 other lysosomal enzymes were either at or above the range of normal control fibroblasts. Total neuraminic acid concentration was 44.3 nmol/mg protein versus an average control value of 14.2. It is concluded that the Goldberg syndrome should be considered, along with mucolipidosis I and the cherry-red spot -- myoclonus syndrome, as resulting from a primary neuraminidase deficiency.

Abnormalities, Multiple↗
PubMed1978

Sialidase (alpha-n-acetyl neuraminidase) deficiency: the enzyme defect in an adult with macular cherry-red spots and myoclonus without dementia.

A 31-year-old male is described who has macular cherry-red spots, increased deep tendon reflexes and and myoclonus without dementia. An older brother died at age 33 of a disease with similar symptomatology. Homogenates of cultured fibroblasts from the patient exhibited 2.6, 8.1 and 12.4% of normal mean sialidase (neuraminidase, N-acetyl-neuraminosyl glycohydrolase, EC 3.21.18) activity, respectively, against 2-(3'-methoxyphenyl)-N-acetyl-alpha-neuraminic acid, N-acetyl-neuramin-lactose and fetuin. Activities of 14 other lysosomal enzymes were within the range of normal control fibroblasts. The sialidase activities in fibroblasts from the patient's parents and children were 30 to 67% of normal. It is concluded that this is the first proven case of a new autosomal recessive disorder resulting in cherry-red spots, myoclonus and a sialidase deficiency.

Adult↗
PubMed1975

Short interval leaf movements of cotton.

Gossypium hirsutum L. cv. Lankart plants exhibited three different types of independent short interval leaf movements which were superimposed on the circadian movements. The different types were termed SIRV (short interval rhythmical vertical), SIHM (short interval horizontal movements), and SHAKE (short stroked SIRV). The 36-minute period SIRV movements occurred at higher moisture levels. The 176-minute period SIHM occurred at lower moisture levels and ceased as the stress increased. The SHAKE movements were initiated with further stresses. The SLEEP (circadian, diurnal) movements ceased with further stress. The last to cease just prior to permanent wilting were the SHAKE movements.

Journal Article↗
PubMed1968

Human-mouse somatic cell hybrids with single human chromosome (group E): link with thymidine kinase activity.

Mouse somatic cells lacking thymidine kinase were mixed in culture with human diploid cells lacking hypoxanthine guanine phosphoribosyl transferase, and hybrid cells were isolated and maintained in a selective medium containing hypoxanthine, aminopterin, and thymidine. The hybrid cells at the time of isolation had karyotypes consisting predominantly of mouse chromosomes but with one human chromosome, a submetacentric member of group E, apparently giving thymidine kinase to the hybrid cell. However, after long-term propagation in the selective medium this chromosome has been lost, although cells continue to show thymidine kinase activity as demonstrated by the incorporation of (3)H-thy-midine into DNA in the hybrid cell. The hybrid cells have only mouse electro-phoretic variants for glucose-6-phosphate dehydrogenase, lactate dehydrogenase, and malate dehydrogenase, suggesting that the human genetic loci for these enzymes are not represented in the hybrid genome and may be unlinked to that for thymidine kinase.

Aminopterin↗
PubMedDate not supplied

Visual adaptation modulates a potassium conductance in retinular cells of the crayfish.

Crayfish photoreceptors exhibit a voltage-dependent potassium conductance, G(K), that is generally similar to the delayed rectifier channel described in neurons and other arthropod retinular cells. G(K) activation (i.e. the apparent threshold, Vth) occurs near the resting potential and G(K) is substantially reduced by 25 mM extracellular tetraethylammonium (TEA) and by intracellular Cs+ injections. Light exposure, sufficient to reduce visual sensitivity 100-fold, increases Vth (shifts it in the depolarizing direction) by about 20 mV. The light-dependent change in Vth does not depend upon the corresponding increase (depolarization) of the steady-state membrane potential nor does it depend upon inward calcium currents. Vth is slightly influenced by fluctuations in Ko associated with the light-elicited currents. During light exposure Ko (measured with K+-sensitive electrodes) increases by 2.1 mM (equivalent to an 8 mV increase in E(K)). This increase in E(K) makes only a modest contribution to the light-dependent change in Vth as determined by perfusion with high potassium salines. Intracellular calcium injections increase Vth by 10 to 20 mV and reduce visual sensitivity by 5- to 10-fold. The results imply that during exposure to high levels of illumination, K+ currents at the steady-state membrane potential are diminished by a calcium-dependent change in G(K) gating and, to a smaller degree, by a reduced K+ concentration gradient. It is notable that Ca2+ appears to inhibit both G(K) and the light-elicited conductance from both inside and outside the plasma membrane. As a consequence of the light-dependent change in Vth, G(K) makes only modest contributions to the changes in sensitivity and speed normally associated with light adaptation. These functions are regulated by the transduction pathway and are revealed at the resting potential in the time course and magnitude of the light-elicited currents.

Adaptation, Ocular↗