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Biomedical subjects

J Yan

Publications and source records attributed to J Yan.

At least 271 records · Page 15Linked to original sources
PubMed1992

Cloning and nucleotide sequence of chloroplast psaA gene from sorghum.

The 6.7 kb EcoRI fragment containing the sorghum chloroplast psaA gene was cloned. The restriction endonuclease map and the nucleotide sequence were determined. The length of the determined nucleotide sequence was 3080 bp, of which the psaA coding sequence was 2253 bp, which encoded a polypeptide of 750 amino acids with a estimated molecular weight of 83000. The homologies of this psaA gene of sorghum with those of maize, rice and spinach were 99.4%, 96.3% and 89.4%, respectively, and the homologies of the deduced polypeptide sequences were 99.3%, 98.0% and 95.7%, respectively. We found that a difference in the profiles of the hydrophobic distribution of P700 apoproteins existed between C4 and C3 plants due to a change occurred at the 493th amino acid (C4 plants: Gly; C3 plants: Arg or Ser).

Amino Acid Sequence↗
PubMed1992

Cardiovascular effects of thyrotropin-releasing hormone in normotensive and hypotensive rats: role of rostral ventrolateral medulla.

To ascertain the central mechanism of the effects of thyrotropin-releasing hormone (TRH) on the cardiovascular system, we evaluated the effects of this neuropeptide on unit fires in the rostral ventro-lateral medulla (RVL), mean arterial pressure (MAP), and heart rate (HR) in normotensive and hypotensive rats. Intracerebroventricular injection (i.c.v.) of 10 micrograms TRH significantly increased MAP and HR in both normotensive and hypotensive rats. No similar effects were observed after saline injection. If electrolytic lesions of bilateral RVL were made, the cardiovascular effects of TRH i.c.v. failed to occur. TRH i.c.v. markedly increased the firing frequency of most units in the RVL. In particular, TRH i.c.v. increased the firing frequency of most units excitatory to a fall in MAP and decreased the firing frequency of most units inhibitory to a fall in MAP in normotensive rats. Moreover, a drop of MAP as low as 40 mmHg for 10 min resulted in an increase of the firing frequency of most units. The effect of TRH i.c.v. on the RVL units in the hypotensive rats was similar to that in the normotensive rats. Our findings suggest that TRH is able to intensify the cardiovascular activities and the RVL plays a key role in the effects of TRH on the cardiovascular system in both normotensive and hypotensive rats.

Animals↗
PubMed1991

[Orthogonal test for the best conditions of treating licorice seeds with sulphuric acid].

Adopting the method of orthogonal test and using the orthogonal table of L25(5(6)), this paper has made a test of the influential factors in treating the licorice seeds with sulphuric acid. The result shows that the best treating conditions are as follows: H2SO4 concentration over 80%. H2SO4 amount 10-20 ml/kg. Treating temperature 10-25 degrees C. Treating time 2 hours.

Analysis of Variance↗
PubMed1991

[Anti-cholinesterase activity of fordine].

The inhibitory effect of fordine on human true cholinesterase (ChE) was found to be 55386 times larger than on pseudo ChE in vitro. There was a marked difference in the inhibition of fordine on pseudo ChE of different species. The order of the decrease of potency of fordine on true ChE of different species was man, dog, rabbit, cat, rat and mouse. The order of the decrease of potency on pseudo ChE was rabbit, rat, dog, cat, mouse and man. In vivo, it was shown that ChE in blood and brain was strongly inhibited by fordine, and the duration of the inhibitory action was comparatively long. The ChE activity inhibited by fordine may recover spontaneously.

Alkaloids↗
PubMed1990

rRNA genes from the lower chordate Herdmania momus: structural similarity with higher eukaryotes.

Ascidians, primitive chordates that have retained features of the likely progenitors to all vertebrates, are a useful model to study the evolutionary relationship of chordates to other animals. We have selected the well characterized ribosomal RNA (rRNA) genes to investigate this relationship, and we describe here the cloning and characterization of an entire ribosomal DNA (rDNA) tandem repeat unit from a lower chordate, the ascidian Herdmania momus. rDNA copy number and considerable sequence differences were observed between two H. momus populations. Comparison of rDNA primary sequence and rRNA secondary structures from H. momus with those from other well characterized organisms, demonstrated that the ascidians are more closely related to other chordates than invertebrates. The rDNA tandem repeat makes up a larger percentage (7%) of the genome of this animal than in other higher eukaryotes. The total length of the spacer and transcribed region in H. momus rDNA is small compared to most higher eukaryotes, being less than 8 kb, and the intergenic spacer region consists of smaller internal repeats. Comparative analysis of rDNA sequences has allowed the construction of secondary structures for the 18S, 5.8S and 26S rRNAs.

Animals↗
PubMed1989

Studies on the structure of HBV DNA.

The structure of HBV adr NC-1 DNA is analyzed and compared with another five strains of HBV DNAs. Some of the prokaryotic promoter-like sequences, palindrom sequences and ATAA are found. An enhancer core sequence and some other characteristics are also shown. In considering the frame and its regulatory sequence as a transcriptional unit some of the possible new frames are discussed.

Base Sequence↗
PubMed1989

Determination of the complete nucleotide sequence of HBV adr NC-1 DNA.

On the basis of sequencing the large DNA-fragments which have been inserted into M13mp8, we design a simple strategy to determine the complete nucleotide sequence of HBV adr NC-1 DNA with chain termination method. The whole genome is 3195 nucleotides long. Five reading frames are observed. The gene location and organization are shown.

Base Sequence↗
PubMed1987

Numbers and proportions of GABA-immunoreactive neurons in different areas of monkey cerebral cortex.

The number and proportion of neurons displaying GABA immunoreactivity were determined for 50-micron-wide columns through the thickness of 10 areas of monkey cerebral cortex, including the precentral motor area (area 4), 3 cytoarchitectonic fields of the first somatic sensory area (areas 3b, 1, and 2), 2 areas of parietal association cortex (areas 5 and 7), the first and second visual areas (areas 17 and 18), area 21 of the temporal lobe, and areas of the orbital and lateral frontal cortex. Methods of fixation and immunocytochemical processing were designed to maximize the number of stained cells in 15-micron-thick frozen sections and 1-micron-thick plastic sections. In 8 of the 10 areas the number and proportion of GABA-immunoreactive neurons per 50-micron-wide column were found to be the same (34-43 cells/column; 25% of the total neuronal population). Areas 17 and 3b differed. Area 17 contained 50% more GABA-immunoreactive neurons (52-66 cells/column) but more than twice the total number of neurons, so that the GABA cells made up less than 20% of the total. In 3 monkeys, the number and proportion of GABA-positive neurons per 50-micron-wide column in area 3b were smaller than in adjacent areas of sensorimotor cortex (26-42 cells/column; 19-22%). In 2 other monkeys, the number and proportion (34-43 cells/column; 24-26%) were the same as in adjacent areas. Despite the similarity among most areas of monkey cortex, within some areas, the number of GABA-positive neurons per 50-micron-wide column varied as much as 30%. These variations form a significant, repeating pattern only in area 18, where narrow bands (150-200 micron wide) of relatively few stained cells alternated with either narrow or wide bands (600-700 micron wide) in which columns contained more cells. The GABA-immunoreactive neurons were unevenly distributed across layers, with every area containing large numbers and proportions of stained cells in layer II, and every area but area 4 displaying a second concentration in the principal thalamocortical recipient layers. In area 4, the number of GABA-positive neurons declined sharply from layer II to layer III and remained low through layer VI. For areas displaying the greatest intra-areal variability, only 1 or 2 layers contributed significantly to that variability (layer IV in area 3b, layers III and V in area 18, and layers II and III in area 17).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Care of very low birth weight infants by neonatal nurse clinicians.

In 1980, the medical facility at the authors' hospital developed a program to train neonatal critical care nurses for primary care provider roles in the intensive care nursery. The neonatal nurse clinician (NNC) program consists of a didactic portion that emphasizes physiology and pathophysiology of sick newborns, and an internship that focuses on the medical needs of very low birth weight (VLBW) neonates. At the completion of the internship, the NNC is assigned to be the primary care provider for infants with birth weights less than or equal to 1,250 g. This report discusses the NNC training program and the five-year experience with the NNC caring for VLBW infants.

Critical Care↗
PubMed1982

The role of the human caudate nucleus in acupuncture analgesia.

The role of the caudate nucleus in acupuncture analgesia was studied in 17 patients receiving caudate stimulation through chronic implanted electrodes to relieve intractable pain caused by late malignancy. Electrical stimulation of the head of the caudate nucleus provided relief from intractable pain in all 17 patients. The pain and pain tolerance threshold were elevated, the alteration in skin galvanic activity, respiratory movement and fingertip plethysmography elicited by a given painful stimulus were depressed. The analgesia required a period of induction and persisted for some time after cessation of stimulation; it showed no obvious segmental topography. These characteristics are similar to those observed in acupuncture analgesia. The effect of caudate stimulation was similar to that of electric needling in depressing the late component of the somatosensory evoked potentials (SEPs) recorded over the scalp and from the centrum medianum of the thalamus. Evoked potentials could be recorded from the caudate nucleus when an acupuncture point was electrically stimulated. The evoked potential record was a complex wave of positive and negative components, the peak latencies of main components being 100-180 msec for positive wave and 148-332 msec for negative wave components. The present study supports the supposition that the caudate nucleus may play a role in acupuncture analgesia. The possibility that the effect of caudate stimulation is brought on by inhibiting the activity of the medial thalamus is discussed.

Acetylcholine↗