Letter: Stereospecific conversion of diosgenin to alpha-ecdysone.
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Ecdysone↗
Biomedical subjects
Y T Liu
Publications and source records attributed to Y T Liu.
Isolation and characterization of a newly identified type II restriction endonuclease from a local Streptomyces sp. in Taiwan.
Streptomyces chusanensis ZS-2, isolated from a soil sample in Chusan in Taiwan, was found to produce a new Type II restriction endonuclease. This restriction enzyme was designated as SchI. The purified enzyme was characterized as having a subunit mol wt of 28 kDa, and was apparently free from exonuclease activities. It cleaves the phosphodiester bond between the fourth C and the fifth G on the 5'-CCGCGG-3' sequence of DNAs, leaving a 2-nucleotide protruding end at its 3' site. This data suggests that SchI is an isoschizomer of SacII. In addition, based on the comparison between SchI and SacII regarding reaction parameters, it seems that SchI is a better choice of restriction enzyme for genetic analysis and mapping.
Base Sequence↗
The global distribution of length polymorphisms of the promoters of the glucuronosyltransferase 1 gene (UGT1A1): hematologic and evolutionary implications.
The promoter region of the UDP glucuronosyltransferase 1 gene (UGT1A1) contains a run of thymine-adenine (TA) repeats, usually six (TA)(6). As well as its relationship to Gilbert's syndrome, homozygosity for the extended sequence, (TA)(7) (TA)(7), has been found to be an important risk factor for hyperbilirubinemia and gallstones in patients with hemoglobin E-beta-thalassemia and other intermediate forms of beta thalassemia. To assess the importance of this polymorphism in these common disorders a wide-scale population study of the relative frequency of the size alleles of the UGT1A1 promoter has been carried out. Homozygosity for the (TA)(7) allele occurs in 10-25% of the populations of Africa and the Indian subcontinent, with a variable frequency in Europe. It occurs at a much lower frequency in Southeast Asia, Melanesia, and the Pacific Islands, ranging from 0 to 5%. African populations show a much greater diversity of length alleles than other populations. These findings define those populations with a high frequency of hemoglobin E-beta-thalassemia and related disorders that are at increased risk for hyperbilirubinemia and gall bladder disease and provide evolutionary insights into how these polymorphisms have arisen and are so unequally distributed among human populations.
Animals↗
GC/MS identification of tetramine in samples from human alimentary intoxication and evaluation of artificial carbonic kidneys for the treatment of the victims.
One day in July 1991, 78 people became victims of accidental alimentary intoxication in a factory in Hebei Province, China. Related samples, including rodenticide bait, the artificial carbonic kidneys used for the treatment of the victims, and the victims' blood, were analyzed by GC/MS. Tetramine [80-12-6], a highly toxic rodenticide, was identified as the toxicant. The effectiveness of artificial carbonic kidneys was evaluated. The analytical results revealed that detoxification of the patients was effective 48 hours after intoxication by percolating their blood through artificial carbonic kidneys.
Bridged-Ring Compounds↗
Non-lethal Candida albicans cph1/cph1 efg1/efg1 transcription factor mutant establishing restricted zone of infection in a mouse model of systemic infection.
The cph1/cph1 efg1/efg1 Candida albicans mutant cells were non-lethal in a mouse model of systemic infection. We investigated in vivo proliferation and invasion of C. albicans cells in infected mice to elucidate the interaction between the host and the pathogen. Homogenates of kidneys from the mice infected with the wild-type and the mutant C. albicans cells yielded a mean of 2.1 x 10 7 CFU/g and 2.2 x 10 6 CFU/g, respectively. The kidneys from the mice infected with the wild-type cells showed extensive renal cortical necrosis associated with neutrophilic infiltration. There were also wild-type hyphal cells present in abundance. Hence, tubular necrosis leading to renal failure in the mice may be the cause of death. Although the cph1/cph1 efg1/efg1 mutant cells were not lethal, they were capable of establishing restricted zones of infection and colonization near the renal pelvis instead of simply being cleared by the immune system in mice.
Animals↗
Encapsulated PC12 cell transplants into hemiparkinsonian monkeys: a behavioral, neuroanatomical, and neurochemical analysis.
Four cynomolgus monkeys were trained on a hand reaching task and then rendered hemiparkinsonian with an intracarotid injection of n-methyl 4 phenyl 1,2,3,6, tetrahydropyridine (MPTP). Performance on this task with the limb contralateral to the MPTP injection was significantly impaired following the lesion. Three monkeys received implants of polymer-encapsulated containing PC12 cells into the caudate nucleus and putamen. One monkey received identical implants of empty capsules and served as a control. After a transient improvement, limb use in the control monkey dissipated and returned to post-MPTP disability. Two of the three PC12 cell grafted monkeys recovered performance on the hand reach task to near normal levels for up to 6.5 mo posttransplantation. Capsules retrieved from the monkeys who recovered limb function postimplantation contained numerous viable PC12 cells that continued to release levodopa, basal dopamine, and potassium evoked dopamine. In contrast, capsules retrieved from the PC12 cell-grafted monkey which did not recover limb use on the hand reach task contained few cells which secreted negligible or undetectable levels of levodopa and dopamine. Interestingly, functional disability was not reinstated following removal of the capsules. Neuroanatomical and neurochemical evaluation of the grafted striatum did not reveal a host-derived sprouting response of catecholaminergic or indolaminergic fibers. These data indicate that xenografts of PC12 cells can survive for up to 6.5 mo in nonimmunosuppressed monkeys when immunoisolated via polymer encapsulation. Moreover, these cells continue to secrete high levels of levodopa and dopamine and induce recovery of motor function in parkinsonian nonhuman primates.
1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗