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Biomedical subjects

C C Lin

Publications and source records attributed to C C Lin.

At least 685 records · Page 38Linked to original sources
PubMed1980

Cytogenetic analysis of great horned owls (Bubo virginianus).

A chromosome analysis of seven great honored owls (Bubo virginianus, Gmelin) has been performed on peripheral lymphocytes. The modal chromosome number was found to be 2n = 82. Measurements of relative lengths and arm ratios of the macrochromosomes were made. All chromosomes contain a region of constitutive heterochromatin in a centromeric location, with the W chromosome being composed almost entirely of this material. Chromosome replication, as demonstrated by the BudR-acridine orange method, showed synchronous replication of the two Z chromosomes of the male and late replication of the W chromosome of the female. In this species, functional regions of nucleolar organization appear to be localized to the microchromosomes.

Acridine Orange↗
PubMed1980

An OCT-reactivity classification to predict fetal outcome.

Based on analyses of the oxytocin challenge test (OCT) in 293 cases, an OCT-reactivity classification is proposed to improve the predictive value of OCT for fetal outcome. All of the 6 perinatal deaths occurred in the 2 groups associated with nonreactive pattern. The positive nonreactive test had 90% accuracy of predicting a sick infant, and the negative reactive test assured good fetal outcome. A nonreactive pattern seems to reflect a compromised fetus, as a high incidence of this pattern was found in patients with pre-eclampsia-hypertension, intrauterine growth retardation (IUGR), low and falling estriol levels, and suspected fetal problems. A positive OCT seems to reflect the limits of fetoplacental reserve under the stressed condition. A high incidence of positive OCT was associated with IUGR, low estriol levels, and a small placenta.

Adult↗
PubMed1979

Mechanism of failed labor after fetal death and its treatment with prostaglandin E2.

Pregnancy was terminated with prostaglandin E2 in 65 women harboring a dead fetus for 3 days to 8 weeks. The study was designed to: (1) elucidate the mechanism of failed onset of labor in the presence of fetal death, (2) determine appropriate dose-response relationships, and (3) evaluate safety and efficacy of this new method of intervention. Results indicate that plasma progesterone levels from 12 to 40 weeks' gestation are in the lower normal statistical range as compared to those seen in pregnancy with a living fetus. Uterine size as estimated from fetal birth weight is also in the low normal range compared to that seen in a viable pregnancy. Hence the uterine volume-progesterone ratio is equal to or greater than that in normal pregnancy and thereby partially explanatory for the failed initiation of labor. The dosage required to produce delivery declined in each month's grouping from a mean of 56 +/- 26 (SD) mg at 12 to 15 weeks to 22 +/- 8.4 mg at 38 to 40 weeks. Dose-delivery response did not correlate with age, parity, or progesterone levels but did correlate with oxytocin response. Three unusual and serious complications occured.

Adult↗
PubMed1979

Purification and properties of a nicotinamide adenine dinucleotide-linked dehydrogenase that serves an Escherichia coli mutant for glycerol catabolism.

Glycerol:NAD+2-OXIDOREDUCTASE (EC 1.1.1.6) was purified to homogeneity from a mutant of Escherichia coli K12 that uses this enzyme, instead of ATP:glycerol 3-phosphotransferase (EC 2.7.1.30), as the first enzyme for the dissimilation of glycerol. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate shows a subunit of 39,000 daltons. During electrophoresis under nondenaturing conditions, the protein migrates as two bands. These two forms, both of which are enzymatically active, appear to be dimers and octomers of the same subunit. The optimal pH for the oxidation of glycerol is about 10, and that for the reduction of dihydroxyacetone is about 6. Glycerol dehydrogenation is highly activated by NH4+, K+, or Rb+, but strongly inhibited by N-ethylmalemide, 8-hydroxyquinoline, 1,10-phenanthroline, Cu2+, and Ca2+. The enzyme exhibits a broad substrate specificity. In addition to glycerol, it act on 1,2-propanediol and several of its analogs.

Cations, Monovalent↗
PubMed1978

The use of base pair specific DNA binding agents as affinity labels for the study of mammalian chromosomes.

The fluorochromes Hoechst 33258 and olivomycin are base pair specific DNA binding agents. The fluorescence enhancement of Hoechst 33258 and olivomycin in the presence of DNA can be directly related to the A--T and G--C content of the interacting DNA respectively. Cytological observations of metaphase chromosomes treated with these two compounds suggest that the fluorescent banding patterns produced are the reverse of one another.--Non-fluorescent base pair specific DNA binding agents have been used as counterstains in chromosome preparations to enhance the contrast of the banding patterns produced by the base specific fluorochromes. The non-fluorescent G--C specific antibiotic actinomycin-D enhanced the resolution of fluorescent bands produced by the A--T specific fluorochrome Hoechst 33258. Similarly the non-fluorescent A--T specific antibiotic netropsin was found to enhance resolution of the bands produced by the G--C -specific fluorochrome olivomycin. Netropsin was also found to increase the differential fluorescent enhancement of complexes of olivomycin with DNAs of various base composition in solution. These findings suggest that counterstaining agents act through a base sequence dependent inhibition of subsequent binding by base pair specific fluorochromes.--The base specific DNA binding agents have been used to differentiate different types of constitutive heterochromatin in mammalian species, and to facilitate chromosome identification in somatic cell hybrids.

Affinity Labels↗
PubMed1978

Interaction of anthracyclines with DNA and chromosomes.

Daunomycin and adriamycin were previously found to produce Q-like banding patterns on chromosomes. The interaction of several anthracyclines with both natural and synthetic DNAs and chromosomes has been investigated in more detail. Daunomycin fluorescence is almost completely quenched by natural DNAs with varying base composition from 31 to 72% G-C and by the alternating polymer poly-d(G-C).poly-d(G-C). In contrast, daunomycin fluorescence is quenched by only 50% when the dye interacts with synthetic A-T polymers. Thus, differential quenching of daunomycin fluorescence can account for the production of bright bands at contiguous A-T sequences along the chromosome. Slight differences in fluorescence quenching between the repeating and homopolymeric A-T duplex DNAs were observed which can be attributed to differences in affinity of daunomycin for these DNAs. The aminosugar moiety of daunomycin, daunosamine, increases the binding of daunomycin to DNA and also enhances chromosome banding.--Nogalamycin, which displays no differential quenching with the different DNAs in solution, also fails to produce bands on chromosomes.--These findings suggest that non-random nucleotide sequence arrangements along the chromosome are a basic determinant for dye interaction to produce the observed banding patterns. Specific banding procedures may determine the accessibility of these sites within the chromosomal DNA.

Animals↗
PubMed1978

Synthesis and antitumor properties of some isoindolylalkylphosphonium salts.

Antitumor evaluation of 2-(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)ethyltriphenylphosphonium bromide (1) revealed significant activity in P-388 lymphocytic leukemia (T/C = 160%). As a follow-up to this chemical lead, a series of closely related phosphonium salts was prepared in which the 1,3-dihydro-1,3-dioxo-2H-isoindole ring system was maintained or in which it was replaced by other moieties such as maleimido, bromo, methoxy, and isoindoline. Syntheses generally involved treatment of the appropriate N-(bromoalkyl)phthalimide with the required phosphine or condensation of the K salt of the substituted imide with beta-(bromoethyl)triphenylphosphonium bromide (12). From the biological data obtained for these compounds, several requirements can be defined for substantial antileukemic activity. Of utmost importance is the presence of a triarylphosphonium halide moiety, coupled to an alkyl chain of two or three carbon atoms. The preferred terminus of the alkyl chain is the 1,3-dihydro-1,3-dioxo-2H-isoindole ring system, although the observed activity of beta-(bromoethyl)-triphenylphosphonium bromide (12) (T/C = 127%) would suggest that a superior carrier molecule could be developed.

Animals↗
PubMed1978

Molecular events during the release of delta-aminolevulinate dehydratase from catabolite repression.

Transfer of exponential-phase cells of Saccharomyces cerevisiae, previously grown in 2% glucose, to a derepression medium resulted in a prompt increase in the level of delta-aminolevulinate dehydratase, the rate-limiting enzyme of heme biosynthesis under these conditions. This derepression exhibited a lag of 35 min at 23 degrees C and required the participation of both RNA and protein syntheses. Dissection of the molecular events during this lag period disclosed that RNA synthesis, rnal gene function (messenger RNA transport from nucleus to cytosol), and initiation of protein synthesis were completed within less than 10, 18, and 24 min, respectively. The potential regulation of derepression by mitochondrial gene products and mitochondrial function was probed by means of a series of isogenic, respiration-deficient (rho-, pet-, and mit-) mutants; no such regulation was found.

Enzyme Repression↗
PubMed1978

A comparative study of five commercial reagents for the Coulter Model S: a proposed method for reagent evaluation.

A comparative study of five competitive commercial reagents for the Coulter Model S was performed jointly by two large, busy hospital laboratories with active quality control programs. Both laboratories, independently using the same reagent systems, studied 20 consecutive blood samples from patients from their own respective hospital for 20 days. Data from both laboratories were analyzed by standard and nonstandard statistical methods, and the results from both laboratories were compared. Although all reagent systems performed reasonably well in a clinical setting, highly significant statistical differences in their precisions were demonstrated by using univariate and multivariate techniques. The statistical method developed in this study can be applied to other systematic investigations that compare reagent systems.

Blood Cell Count↗
PubMed1978

Deceleration/contraction ratios as an index of fetal health during labor.

Internal FHR tracings of 259 patients with variable decelerations and 49 with late decelerations were analyzed for frequency and severity of the pattern in an attempt to correlate with fetal pH or Apgar score at 1 minute. A significant increase in the risk of fetal acidosis was associated with a frequency of greater than 30% variable decelerations and 20% late decelerations. It also increased with the increase of severity of the pattern. Variable decelerations are not good predictors of Apgar scores less than or equal to 6 at 1 minute, but late decelerations are predictive when they occur more than 20% of the time. The fetus with variable decelerations a normal pH can be observed through the first stage of labor with a high degree of confidence. However, when a 20% or more moderate-to-severe late deceleration/contraction ratio is present, intervention is necessary even if scalp blood pH is normal. The FHR deceleration/uterine contraction (UC) ratio is a simple bedside technique for assessing fetal outcome.

Acidosis↗
PubMed1978

Postpartum uterine pressures under halothane or enflurance anesthesia.

Postpartum uterine pressures were measured in healthy women with an intrauterine microballoon before, during, and after administration of different concentrations of halothane or enflurane. Arterial blood samples for anesthetic levels were obtained at intervals. Frequency and intensity of contractions diminished markedly when blood levels exceeded the equivalent of 1/2 MAC (minimum alveolar anesthetic concentration which produces immobility in one-half of subjects exposed to a noxious stimulus) of nonpregnant adults, but normal patterns returned promptly on lightening of anesthesia. Response to 10 mU of oxytocin was suppressed at blood levels corresponding to between 3/4 and 1 MAC of the agents. Halothane and enflurane exert equipotent dose-related reversible effects on the activity of the full-term pregnant human uterus.

Anesthesia, Inhalation↗