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Biomedical subjects

B Li

Publications and source records attributed to B Li.

At least 703 records · Page 39Linked to original sources
PubMed1993

1,25-dihydroxyvitamin D as a cardiovascular hormone. Effects on calcium current and cytosolic free calcium in vascular smooth muscle cells.

Clinical and in vitro evidence suggests a role for the calcium regulating hormone, 1,25-dihydroxyvitamin D (1,25D) in human and experimental hypertension. To establish the cellular basis for this association, we utilized the whole-cell version of the patch clamp method and fluorescence spectroscopic techniques to measure voltage-dependent calcium channel activity and cytosolic free calcium concentrations ([Ca2+]i) in rat tail artery-derived smooth muscle cells, before and after the addition of 1,25D. 1,25D significantly increased the calcium channel current over the range of test pulses, from -40 to +60 mV, in a dose- and time-dependent manner, appearing by 5 to 10 min of exposure, with maximum effects by 15 min. At 10 and 30 nmol/L, the current increased to 149 +/- 10% and 221 +/- 13% of basal activity of 37.75 +/- 7.7 pA and 37.7 +/- 4.5 pA, respectively. Similarly, at 10 and 100 nmol/L, 1,25D increased cytosolic free calcium levels 115 +/- 2% and 171 +/- 11%, from basal values of 99 +/- 32 nmol/L and 116 +/- 10 nmol/L, respectively. These effects of [Ca2+]i developed slowly over 3 to 4 min. Peak values were achieved by 30 min of incubation and were reversible with removal of 1,25D from the medium. Altogether, these direct effects of 1,25D on calcium current and [Ca2+]i in vascular smooth muscle cells support a role for 1,25D in vascular physiology, and provide a cellular basis for better understanding the involvement of 1,25D in hypertensive vascular disease.

Animals↗
PubMed1993

Identification of mutations in p53 that affect its binding to SV40 large T antigen by using the yeast two-hybrid system.

The tumor suppressor p53 protein binds to the products of several viral oncogenes, including SV40 large T antigen. We reconstructed the p53-T antigen interaction in the yeast two-hybrid system, a genetic assay that uses the reconstitution of the activity of a transcriptional activator to detect protein-protein interactions. Using mutants of T antigen known to be defective in binding to p53, we demonstrate that the two-hybrid system is more sensitive than immunoprecipitation in the detection of weak interactions. We mutagenized the murine p53 gene and screened in the yeast assay for decreased reporter gene expression indicative of the failure of p53 to bind T antigen. This screen identified 34 p53 mutants, almost all of which contain at least one mutation in the conserved domains frequently found mutated in human cancers. These results support the idea that the function of the wild-type p53 protein requires residues involved in binding to T antigen, and indicate that this approach may be generally applicable in the analysis of protein-protein interactions.

Amino Acid Sequence↗
PubMed1993

VP4 serotype of the Gottfried strain of porcine rotavirus.

The antigenic relationships of the VP4 serotype of porcine rotavirus Gottfried strain with other rotaviruses were determined by using antiserum to Gottfried VP4-baculovirus recombinant. This antiserum failed to react significantly with virus of serotypes P1A, P1B, P3, and OSU; however, it reacted with P2 strains. In the reciprocal assay, antiserum to VP4 of an asymptomatic strain (P2) failed to neutralize the Gottfried strain virus to a significant level. It thus appears that the Gottfried strain should be considered a subtype of P2.

Animals↗
PubMed1993

Restriction endonuclease analysis of the vp7 genes of human and animal rotaviruses.

The vp7 genes of 194 strains of group A rotaviruses representing all known G types were analyzed with three restriction enzymes by direct digestion of amplified cDNA copies or by deduction of the restriction patterns from known sequences. Mammalian rotavirus strains were classified into 28 restriction patterns consisting of combinations of the 6 profiles (s1 to s6) obtained by digestion with Sau96I endonuclease, 9 profiles (h1 to h9) obtained with HaeIII, and 15 profiles (b1 to b15) obtained with BstYI. Digestion with Sau96I and HaeIII identified restriction sites common to all, or almost all, rotavirus strains studied, whereas BstYI was the most discriminating among rotavirus strains. A clear correlation between some restriction patterns or individual profiles and G type and/or host species of origin was found. Several discriminatory restriction sites consisted of type-specific nucleic acid sequences that encoded conserved amino acid residues. Although not directly involved in antigenic diversity, these sites appear to indicate the G type of the isolate. The technique permits rapid comparison of a large number of virus isolates directly from fecal specimens and provides useful markers for investigating the evolution of rotavirus vp7 genes and tracing vaccine virus and interspecies transmission.

Animals↗
PubMed1993

Human rotavirus K8 strain represents a new VP4 serotype.

The complete VP4 gene of the human rotavirus (HRV) K8 strain (G1 serotype) was cloned and inserted into the baculovirus transfer vector pVL941 under the control of the polyhedrin promoter. A K8VP4 recombinant baculovirus was obtained by cotransfection of Spodoptera frugiperda (Sf9) cells with transfer vector DNA containing the K8VP4 gene and wild-type baculovirus DNA. Infection of Sf9 cells with this VP4 recombinant baculovirus resulted in the production of a protein that is similar in size and antigenic activity to the authentic VP4 of the K8 strain. Guinea pigs immunized with the expressed VP4 developed antibodies that neutralized the infectivity of the K8 strain. This antiserum neutralized HRV strains belonging to VP4 serotypes 1A, 1B, and 2 with efficiency eightfold or lower than that of the homologous virus, indicating that the human rotavirus K8 strain represents a distinct VP4 serotype (P3). In addition, low levels of cross-immunoprecipitation of the K8VP4 and its VP5 and VP8 subunits with hyperimmune antisera to HRV strains representing different VP4 serotype specificities also suggested that the K8 strain possesses a unique VP4 with few epitopes in common with other P-serotype strains.

Animals↗
PubMed1993

LH pulsatility, biopotency, and clearance during undernutrition in orchidectomized mature rats.

The effect of food restriction on circulating luteinizing hormone (LH) levels in orchidectomized rats is controversial. The present study demonstrates that decreasing food intake by 50% for 3-10 days in orchidectomized rats increases LH pulse amplitude, length, area under pulse curve, and mean levels but decreases LH pulse frequency compared with ad-lib fed, orchidectomized controls. The effects on pulsatile LH secretion of food reduction by 50% with or without dilution by cellulose to maintain food volume in orchidectomized rats were also examined. Food volume influences pulsatile LH secretion independent of macronutrient effect after 3 days of food restriction, but subsequently macronutrient deprivation predominates. The exaggerated increase in LH levels in orchidectomized rats subject to food restriction for 7 days was not due to immunochemical or chromatographic heterogeneity or alteration in biopotency of circulating LH molecules. Intravenously injected 125I-labeled rat LH analyzed by noncompartmental modeling revealed that neither LH clearance nor mean residence time was reduced by food restriction. We conclude that during food restriction in orchidectomized rats, increases in LH pulse amplitude exceed and precede the decreases in LH pulse frequency, although the early changes in pulse amplitude are predominantly due to reduced food volume rather than macronutrient deprivation.

Aging↗
PubMed1993

[Evidences for the appearance of peripheral activator during the advance of PSM].

Investigation on mechanism underlying the formation of the propagated sensation along meridians (PSM) is one of the important problems in meridian research. In order to interpret the problem more satisfactorily, we had advanced a hypothesis in 1987, that is, 'integration of periphery' and CNS under the domination of substantial process proceeding along the meridians". According to this hypothesis, "periphery" and "central mechanism" are operated as a whole. However, it also emphasized that the peripheral substantial process is the determinant factor in the formation of PSM. And then, is there really a peripheral substantial process, or, in other word, a peripheral activator during the advance of PSM. The afferent discharges were directly led from the superficial branch of radial nerve. Nineteen volunteers with marked PSM were under observation. The preliminary results demonstrated that as PSM, evoked by stimulating Jianyu (LI15) or Ying Xiang Acupoint (LI20), travelled along the course of Large Intestine Meridian to the hand or index finger, the corresponding afferent impulses could be recorded from that nerve branch in a part of experiments. Through a series of control observations, it has been proved that the impulses recorded was not resulted from other responses, but really the afferent impulse discharged by the neuroreceptor apparatus distributing along the meridian, which was activated by certain stimulation. The facts demonstrated that "the peripheral activator" really appeared during the advance of PSM. It is of significance for the investigation on the mechanism underlying the formation of PSM.

Acupuncture Points↗
PubMed1993

[Observation on the functional characteristics of cortical somatosensory area during the advance of the propagated sensation along meridians].

It is still not clear what role is played by cortical somatosensory system during the advance of propagated sensation along meridians (PSM). In this paper the short-latent somatosensory evoked potential (SLSEP) was taken as an indication to observe the characteristics of functional activity in cortical somatosensory area I (SI) during the advance of PSM. The observation was preformed on 10 subjects with marked PSM, which were clear and kept stable. Sixteen subjects without SPM were taken as control. Electrical stimulation was delivered to the acupoint Jiaxi (GB43) or Hegu (LI4). The SLSEP were recorded simultaneously from 3 scalp points corresponding to the representative areas of foot, arm and face contralateral to the stimulated side. The results are shown as follows. When Jiaxi was stimulated, the amplitudes of SLSEP component C2 (P45-N55) from above three scalp points in subjects without PSC were 0.85 +/- 0.17, 0.51 +/- 0.11 and 0.31 +/- 0.07 microv respectively. The amplitude was largest in the foot representative area, but attenuated successively in arm and face areas and a stair-shaped distribution was thus formed. During stimulating the acupoint Hegu (LI4) the amplitude of SLSEP component C2 (P25-N55) from the representative area of arm in subjects without PSM was larger than that from the representative areas of foot and face, and a distribution with high-medium and low-bilateral character was shaped. However, no matter whether stimulating Jiaxi or Hegu the amplitude of SLSEP C2 in subjects with marked PSM was nearly the same from three scalp points.(ABSTRACT TRUNCATED AT 250 WORDS)

Acupuncture Points↗
PubMed1993

[Localization of the meridian track over body surface by the method of blocking the acupuncture effect with mechanical pressure].

Plotting out the meridian course with objective methods is one of the important projects in the research of meridian at present. Therefore, selecting a proper indication to plot out the meridian track over the body surface during acupuncture is significant for elucidating the essence of meridian. The purpose of this paper was to plot out the Large Intestine Meridian track by blocking the acupuncture effect with mechanical pressure, when electroretinogram (ERG) was taken as a responsive indication. The plotting out the track was carried out on 5 subjects with marked propagated sensation along meridians (PSM) and 5 without PSM. The pressure was applied on Wenliu (LI 7), Shoushanli (LI 10), Quchi (LI 11), Binao (LI 14) and Jianyu (LI 15) respectively, when Hegu (LI 4) was punctured. Under such condition the variation of ERG amplitude decreased markedly or even disappeared. But the variation rate of ERG amplitude was still distinctly increased when the pressure was applied on both sides of any above points. The difference is highly significant (P < 0.01). The results revealed that the meridian track over the body surface during acupuncture could be plotted out not only in the subjects with marked PSM, but also in those without PSM, when the proper objective indication was used. Its course basically coincided with that of the meridian described in the books of traditional Chinese medicine. Now it is safe to say the meridian track over the body surface is existed in human in common. It provides a new approach to plot out the meridian course with objective methods and opens up broad prospects for further application.

Acupuncture Points↗
PubMed1993

[The influence of pressing the meridian course on electroretinogram during acupuncture].

Observation was performed on 23 subjects with marked propagated sensation along meridians (PSM) and 30 without PSM. The electroretinogram (ERG) was recorded with surface electrode and added by an averager. The b wave of ERG evoked by flash stimulation was positive with a latent period about 60 ms and amplitude of 22 +/- 1.66 muv (n = 53). There were 2 types of ERG response during puncturing Hegu (LI 4). The amplitude of ERG b wave increased in 33 subjects and decreased in 20 subjects. However, the acupuncture effect was kept relatively stable in each subject. The spontaneous variation of ERG amplitude was about 10%. In contrast, it changed by 26.5 +/- 2.43% (n = 20) when Hegu (LI 4) was acupunctured alone. It is particularly to be noted that the amplitude of b wave almost remained unchanged, with in the range of 10.08 +/- 2.42% (n = 20), as the pressure was applied on Shousanli (LI 10) during acupuncture, no matter whether the subjects with or without PSM. However, the variation rate of b wave increased by 24.83 +/- 3.74% (n = 15) once again, if the pressure was applied on both side of Shousanli (LI 10), it was nearly equal to the value caused by acupuncture Hegu (LI 4) alone. The contrast between the two is striking. The result revealed again that there may be a certain substantial process advancing along the channel during acupuncture. It is the blockade of this process by mechanical pressure which leads to the decrease of the acupuncture effect.

Acupuncture Therapy↗
PubMed1993

[Observation on the relation between propagated sensation along meridians and the therapeutic effect of acupuncture on myopia of youngsters].

Nine hundred and ninety two eyes suffering from various degrees of myopia in 536 youngsters were treated with acupuncture. A method of exciting propagated sensation along meridians (PSM) and making it travel toward the affected region was employed in treatment. Bilateral Hegu (LI4) and Taichong (LR3); and bilateral Waiguan (ST5) and Guangming (GB37) were punctured on alternate days. The results showed that after 1-3 periods of treatment, the vision of 868 eyes (87.5%) were improved in various extent. Among them, the vision completely recovered in 131 eyes (13.31%), and the diopter decreased-0.75 to -1.00 D.S. in 13 eyes after acupuncture treatment. The therapeutic effect of acupuncture seemed to be considerably satisfactory and stable in two years following up. The extent of distinctness of PSM raised markedly with the increase of times of acupuncture. There was a close relation between the extent of distinctness of PSM and effectiveness of acupuncture. The more striking the centripetal PSM, the better was therapeutic effect of acupuncture. The excellent effect was always achieved when PSM arrived at the affected eye. Since PSM arrived at a large number of eyes in the subjects in younger year and so the better therapeutic effect was also achieved.

Acupuncture Therapy↗
PubMed1993

[Observation on the phenomenon of propagated sensation along meridians in youngsters].

That the opinion on the relation between the propagated sensation along meridians (PSM) and the age of the subjects was divergent in the results reported by some authors. In the last 10 years, we have performed a systematic investigation on PSM on a group of 536 youngsters. The main characteristics of PSM in youngsters were just the same as that of adults. However, the incidence of PSM in youngsters, particularly the degree of distinctness of PSM, was by far higher than that of adults. The results were stable and could be repeated in the experiments performed in different years. It showed that there was surely a close relation between the degree of distinctness of PSM and the age of subjects. This fact can not be appropriately explained at present. However, it provides an important clue to clarify the factors which influence the appearance of PSM, and in turn to promote the improvement of the therapeutic effect of acupuncture and cilacriation of the mechanism underlying the formation of PSM.

Acupuncture Therapy↗
PubMed1993

[The study of the RFLP of D14S13 site of human genome].

The single-locus probe pCE 1.2 recognizes the D14S13 site in human genome. Allele-frequency of HaeIII digested D14S13 site is drawn out from 269 unrelated individuals. It displayed that there were at least 66 alleles and more than 93% heterogeneity. No mutation in 93 individuals of 8 families was observed. This RFLP technique has been applied in the identification and parentage testing in forensic science, and the accuracy of identity was calculated. Some further applications were discussed.

Alleles↗