Metallocene interactions with DNA and DNA-processing enzymes.
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Antineoplastic Agents↗
Biomedical subjects
A H Liu
Publications and source records attributed to A H Liu.
Phylogenetic relationships among two species of golden monkey and three species of leaf monkey inferred from rDNA variation.
Restriction maps of rDNA repeats of five species of Colobinae and three outgroup taxa, Hylobates leucogenys, Macaca mulatta, and Macaca irus, were constructed using 15 restriction endonucleases and cloned 18S and 28S rRNA gene probes. The site variation between Rhinopithecus roxellana and Rhinopithecus bieti is comparable to that between Presbytis françoisi and Preshytis phayrei, implying that R. bieti is a valid species rather than a subspecies of R. roxellana. Phylogenetic analysis on the 47 informative sites supports the case for Rhinopithecus being an independent genus and closely related to Presbytis. Furthermore, branch lengths of the tree seem to support the hypothesis that the leaf monkeys share some ancestral traits as well as some automorphic characters.
Animals↗
Diaphragmatic flutter presenting as inspiratory stridor.
Diaphragmatic flutter is a rarely reported disorder in which the diaphragm involuntarily contracts at a rapid rate. We report a unique case in which diaphragmatic flutter was associated with inspiratory stridor and was severely disabling. A new approach to the treatment of this condition, phrenic nerve crush, provided an optimal outcome, with resolution of symptoms and the return of normal diaphragmatic function. Pathophysiology and treatment of this condition are discussed.
Adolescent↗
Multiple genotypes of mitochondrial DNA within a horse population from a small region in Yunnan Province of China.
mtDNA genotypes of six domestic horses (three adult short horses whose heights are under 1 m and three common domestic horses) from a small region of 15 km2 in Malipo county of Yunnan province of China were investigated by the technique of restriction fragment length polymorphism (RFLP) with 16 restriction endonucleases which recognize 6-bp sequences. An average of 56 fragments for an individual was obtained. Unlike other domestic animals, this population of horses exhibits high mtDNA genetic diversity. Each of the six horses has a specific mtDNA genotype showing a pattern of multiple maternal origins, as suggested by fossil and literature records. We think the population of horses is an amazing seed-resource pool of horses and hence deserves to be paid more attention from the view of conservation genetics. However, it is also remarkable that we did not find any typical mtDNA genetic markers which would discriminate between short horses and common domestic horses.
Animals↗
Sequencing heavy- and light-chain variable genes of single B-hybridoma cells by total enzymatic amplification.
We have devised a protocol to obtain accurate and complete sequences of the immunoglobulin heavy- and light-chain variable-region (VH and VL) genes of single B-hybridoma cells that express defined V genes. The amplification achieved ranges from 2 x 10(13)- to 1 x 10(14)-fold. Only one potential Taq DNA polymerase error was observed in 7590 nucleotides of sequence, thus permitting the identification of naturally occurring somatic mutations. The two-step nature of the amplification protocol provides sufficient DNA for a minimum of 160 sets of sequencing reactions of both the VH and VL genes from one cell without cloning. The amplification of relatively long segments of DNA in the first step of the protocol permits second-step amplification and sequencing of regions that flank VH and VL codons. Fractionating cellular lysates prior to the first step of amplification permits the separate amplification of V genes on opposite sister chromatids and possibly on opposite strands of the same DNA duplex. Accurate sequencing of VH and VL genes of defined germ-line origin that are expressed by single B cells taken directly from the animal is thus made feasible by this approach.
Animals↗
Allergy and asthma: classic TH2 diseases (?).
More than a decade of cytokine immunology has revealed a central role for pro-allergic TH2-like cytokines in the immune pathogenesis of allergic diseases and asthma. Of these, IL-4, IL-5, and IL-13 are produced mostly by T lymphocytes; more recently, numerous other immune cell types have been found capable of producing these cytokines as well, although their role in mediating atopic disease pathogenesis is less well understood. In contrast, the counterregulatory cytokine IFN-gamma can inhibit both the production and activities of the pro-allergic cytokines; therefore, central to the atopic diseases is a paradigm of cytokine imbalance, with overproduction of the TH2-like cytokines, and a relative deficiency of IFN-gamma production. Intriguing recent evidence is that all humans are TH2-like cytokine "skewed" at birth, due to maternal-fetal immune biology imperatives. However, further investigations suggest that IFN-gamma is likely to be pro-inflammatory in many if not most aspects of chronic allergic inflammation. Therefore, our understanding of these "classic TH2" diseases evolves, with important insights that will serve to optimize therapeutic strategies and investigations in the new millennium.
Asthma↗
Allergy and asthma prevention: the cup half full.
Lack of an effective approach to atopic disease prevention is implicit in the global rise in asthma and allergy prevalence over the last 10-20 years. Indeed, asthma appears to be the most common chronic disease of childhood, allergies seem more common than not, and recent evidence suggests that this atopic disease burden is influencing adult prevalence of these conditions as well. Thus, the time seems right for prevention. Considering our current understanding of asthma and allergy pathogenesis, numerous strategies of atopic disease prevention can be envisioned. These strategies can be organized as follows: (1) allergen avoidance; (2) anti-inflammatory pharmacotherapy; (3) inhibition of Th2-type immune development by Th1-type cytokine induction; and (4) dietary and environmental approaches to atopic disease prevention.
Adult↗
Endotoxin: friend or foe?
Endotoxin in our living environment has been of increasing interest to our global community of allergists. Initially and largely studied for its capacity to mediate septic shock (and earning its "-toxin" suffix), we have since come to understand that endotoxin in the dust of many occupational settings also is an occult respiratory culprit, inducing airflow obstruction and aggravating asthma and allergies. More recently, environmental endotoxin has been implicated as a microbial exposure in early childhood that may have an atopy-protective effect by augmenting early Th1-type immune development. Although seemingly paradoxical, endotoxin's dual nature ultimately may serve to enlighten our understanding of how such bioactive exposures can interact with and guide our immune systems in both health and disease.
Air Pollutants↗