Biomedical subjects

P Li

Publications and source records attributed to P Li.

At least 343 records · Page 19Linked to original sources

PubMed1998

[Detection of Epstein-Barr virus subtypes in Hodgkin's disease].

OBJECTIVE: To investigate Epstein-Barr virus (EBV) subtypes in Chinese patients with Hodgkin's disease (HD). METHODS: 113 cases of HD patients with EBV latent membrane protein 1 (LMP-1) and/or EBV encoded small RAN (EBER-1) positive and throat washings from 21 healthy persons were studied for EBV subtypes by polymerase chain reaction (PCR). RESULTS: 68 HD cases exhibited specific bands, in which 62 cases were EBV type A and 6 cases were EBV type B. 13 of the control washing gave rise to specific bands, of which 11 were EBV type A and 2 of EBV type B. CONCLUSION: The results showed that EBV type A is predominant in Chinese HD patients and healthy individuals.

Adaptor Proteins, Signal Transducing↗

PubMed1998

[The correlation between Burkitt's lymphoma and Epstein-Barr virus in 28 cases and their expression of p53 and bcl-2 proteins].

OBJECTIVE: To investigate the correlation between Burkitt's lymphoma and Epstein-Barr (EB) virus and its expression of p53 and bcl-2 proteins. METHODS: Polymerase chain reaction (PCR), in situ PCR and immunohistochemical techniques were applied to specimens from 28 cases of Burkitt's lymphomas on paraffin-embedded sections. RESULTS: EB virus was found in 8 (28.5%) cases by PCR, of which 3 were positive by in situ PCR. Positive rates for the expression of p53 and bcl-2 were 44.4% and 48.1% respectively. Whereas in stages I-II and III-IV, they were 3(23.0%), 9(64.2%) and 3(23.0%), 10(71.4%) respectively. Both the expression of p53 and bcl-2 were high in stages III-IV, low in stages I-II (P < 0.05). The positive cases of EB virus in combination with the expression of p53 and bcl-2 protein, p53 protein and bcl-2 protein were 4,5,4 respectively and 9 cases were positive for p53 and bcl-2 protein. In other words, the positive cases for EB virus in combination with the expression of p53 and bcl-2 were 50%, whereas 70% were positive for both p53 and bcl-2. CONCLUSIONS: The positive rates of EB virus in our series are different from some reports of African-Burkitt's and similar to many other reports of endemic Burkitt's lymphoma. The expression of p53 and bcl-2 proteins are significantly correlated with stage; high in stages III-IV and low in stages I-II. EB virus, p53 and bcl-2 proteins may affect each other.

Adolescent↗

PubMed1998

[Repeat operations for recurrent trigeminal neuralgia after microvascular decompression].

For the study of cause and treatment of recurrent trigeminal neuralgia, repeat operations were performed in 12 patients with recurrent trigeminal neuralgia after microvascular decompression. Among repeat operations, there was vascular loop recompression at trigeminal root in 10 patients, negative exploration in 2 patients. The pain relief was achieved after neurovascular redecompression or neurolysis in all patients. The patients had no recurrent pain during a follow-up from 6 months to 4 years. The causes of recurrent trigeminal neuralgia after microvascular decompression and the questions related to repeat operations were discussed.

Adult↗

PubMed1998

[The central mechanism of the high frequency component in heart rate variability in rat].

Experiments were performed on 15 Sprague-Dawley rats to detect the effect of artificial ventilation of different frequencies on the high frequency component of heart rate variability (HRV) by autoregressive modeling with Burg algorithm. With continuous or intermittent electrical stimulation, different patterns of regulating activity of nucleus ambiguus in medulla on HRV were observed. Fast Fourier transform was used to analyze the coherence between neuronal discharge with respiratory rhythm in rostral ventrolateral medulla (rVLM) and HRV. The results showed that (1) the central frequency of high frequency (HF) component of HRV were moved closely with frequencies of artificial ventilation, (r = 0.83, P < 0.0001); (2) there was a favorable coherence between neuronal discharge with respiratory rhythm in rVLM and HRV in HF on spectrum, (k2 = 0.854 +/- 0.1); (3) the area of HF component in HRV was increased significantly during intermittent electrical stimulation of nucleus ambiguus in medulla. The central frequency of HF component in HRV was influenced mainly by frequencies of respiration. These results indicate a significant correlation between the HF in HRV and neuronal discharge with respiratory rhythm in rVLM, suggesting that rVLM participates in the regulation of HRV. The HF component of HRV may reflect mainly the fluctuating activity of vagal center. Coherence analysis of two signals provides a new method to confirm the type and interaction of neurons in the central cardiovascular system.

Animals↗

PubMed1998

Inhibitory effect of GABA on firing activity of rostral ventrolateral medullary neurons of rat in vitro.

Extracellular single-unit discharges were obtained from 106 spontaneously active neurons in the region of the rostral ventrolateral medulla (RVLM) by glass microelectrode from 73 brain alices of Sprague-Dawley rats. Exogenous gamma-aminobutyric acid (GABA, 0.1-3.0 mmol/L) inhibited the electrical activity of 84 out of 106 RVLM neurons dose-dependently. The inhibitory effect of GABA could be blocked by GABAA receptor antagonist bicuculline methiodide (BMI) and Cl- channel blocker picrotoxin (PTX). When perfused with BMI or PTX alone, the firing rates of most of the RVLM neurons were significantly increased. In 41 neurons responding to GABA, baclofen (0.1-3.0 mumol/L), a GABAB receptor selective agonist, inhibited the discharges of 33 of the neurons dose-dependently. GABAB receptor antagonist CGP35348 (n = 13) blocked the inhibition due to baclofen (n = 21). After perfused with CGP35348 alone, the firing rates of most of the RVLM neurons were significantly increased. Taken together, the inhibition of GABA on RVLM neurons is mediated through either GABAA or GABAB receptors and some intrinsic GABA neurons exert tonic inhibition activity.

Animals↗

PubMed1998

[Effect of activities of vagi and sympathetic nervous system on heart rate variability].

Experiments were performed on rabbits anaesthetized with urethane and chloralose. The electrocardiogram (ECG), heart rate (HR), and blood pressure (BP) were recorded and the power spectrum density (PSD) of R-R interval was analysed by a computer. The low frequency component (LF) was higher during the respective stimulation of the nucleus ambiguous, depressor nerve, and the peripheral end of right vagus with a low frequency fluctuant style than with a monotonous style (P < 0.05). Intravenous infusion of phenylephrine resulted in increases of total variance of RRI (TV), very low frequency components (VLF), LF, high frequency components (HF) and LF/HF during the first 256 RRI only (P < 0.05-0.01). In order to observe the influence of different activities of sympathetic nerves on heart rate variability (HRV), DL-homocysteine (DLH) was microinjected into the vicinity of N. Paraventricularis of hypothalamus. This injection caused increases of the TV, LF, LF/HF and VLF during the rising phase of BP and HR, but no significant change occurred at the plateau period of high BP and HR. These results suggest that heart rate variability mainly reflects the fluctuation of vagal and sympathetic tone.

Animals↗

PubMed1998

Convergence of midbrain, visceral and somatic inputs onto neurons in the nucleus paragigantocellularis lateralis in rats.

Extracellular recordings were made in nucleus paragigantocellularis lateralis (PGL) of the rat in response to stimulation of the dorsal periaqueductoral gray matter (dPAG), ventrolateral periaqueductuctoral gray matter (vPAG), deep peroneal nerve (DPN), median nerve (MN) and great splanchnic nerve (GSPL). Stimulation of dPAG or MN evoked mainly excitatory responses while the responses to stimulation of vPAG were inhibitory. However, stimulation of GSPL or DPN produced both inhibitory and excitatory responses. These neurons were not only responsive to one stimulation site, but were likely responsive to any other stimulation sites. Eighty-nine percent of cells tested (73/82) received convergent inputs from two or more sites. Sixty percent (21/35) of the neurons were identified as cardiovascular units based on their barosensitivity and slow conduction velocities of the descending axons projecting into the spinal cord. This result provided new evidence for the integrative function of neurons in PGL under some circumstances.

Afferent Pathways↗

PubMed1998

[Investigations on the incidence of dental wedge-shaped defects and abrasion in 501 elderly population and their correlation].

OBJECTIVE: To investigate the incidence of the wedge-shaped defects and abrasion their correlation in elderly. METHODS: 501 elderly were examined. RESULTS: The prevalence of wedge-shaped defects was 89.62% and the abrasion was 100.00%. Both the occurrence rate and abrasive degree were all significantly related with the age and the location of tooth. Patients with severe abrasion had severe wadge-shaped defects. CONCLUSION: The wedge-shaped defects and abrasion are common dental diseases in elderly. There would be some common factors in causing both lesions, but the factors that promote the abrasive degree are different.

Aged↗

PubMed1998

[Local amyloidosis of stomach].

OBJECTIVE: To improve the diagnostic rate of local amyloidosis of stomach. METHOD: One case of local amyloidosis of stomach was reported and the literatures were reviewed on the etiopathology, clinical features, diagnosis, treatment and prognosis. RESULT: The patient was negative for family history and other chronic disease. Total gastrectomy was taken and was eventually found to have localized amyloidosis of stomach and regional lymph nodes. The amyloidosis was found to be of AA amyloidosis. Multiple biopsy specimens taken from esophagus, duodenum, rectum and bone marrow showed no amyloid deposition. CONCLUSION: Amyloidosis should be considered in the differential diagnosis of gastric tumors, and also should be removed by operation if complications are to be prevented.

Amyloidosis↗

PubMed1998

[11 beta-Hydroxysteroid dehydrogenase].

There are two types of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD). 11 beta-HSD 1 is an oxoreductase interconverting biologically active cortisol and inactive cortisone. 11 beta-HSD 2 is an exclusive oxidase only converting cortisol to cortisone. It has been recognized that 11 beta-HSD 2 confers the specificity of mineralocorticoid receptor in the kidney and protects the fetus from high levels of maternal glucocorticoids in the placenta. Lack or malfunction of this enzyme could result in the development of apparent mineralocorticoid excess syndrome and intrauterine growth retardation of the fetus. 11 beta-HSD is possibly involved in a number of other physiological and pathological conditions such as stress, hypertension, diabetes mellitus and neurodegenerative disorders. The functions of 11 beta-HSD 1 are not very well understood.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗

PubMed1998

[Isolation and identification of Rhodopseudomonas acidophila from Fujian province, China].

A strain P301 of Gram negative purple nonsulfur bacterium was isolated from the ditch's mud collected in Fuzhou, Fujian. The cells are rod-shaped. Multiplication occur by budding without stalk formation. Growth optimum pH is 5.0-5.7. No growth factors required. The cells contain bacteriochlorophyll a. The photosynthetic membrane system consists of parallel lamellae. According to Bergery's Manual of Determinative Bacteriology, 8th ed. (1974) and 9th ed. (1994), the strain was identified to be Rhodopseudomonas acidophila. But on the side of enzyme activity, utilization of organic substrates and others the strain some differ from the type strain described by N Pfennig (1969). Therefore the strain P301 was identified to be Rhodopseudomonas acidophila var. fujianensis n. var.

China↗

PubMed1998

[The measurement of baroreflex sensitivity in stress-induced hypertensive rats by spectral analysis].

Simultaneous spectral analysis of short-term systolic blood pressure variability (SBPV) and heart rate variability (HRV) was applied to determine the change of baroreflex sensitivity (BRS) in Sprague-Dawley (SD) rats. The modulus of the transfer function between fluctuations in systolic pressure and beat-to-beat interval would be an appropriate quantification of BRS. The animal experiment was performed on two groups of rats: normotensive rats and stress-induced hypertensive rats (SIHR). V1-receptor antagonist d(CH2)5Tye(Me) AVP of arginine vasopressin (AVP) was microinjected into intracerebroventricle. The results showed that, in base-line condition before administration, although the BRS in very low frequency band (0-0.035 Cycle/Beat, VLF), low frequency band (0.035-0.12 Cycle/Beat, LF), high frequency band (0.12-0.32 Cycle/Beat, HF) and total BRS(the sum of the three bands) were all decreased, the BRS in VLF(P < 0.05) and LF(P < 0.01) decreased significantly by statistics; and that, to the SIHR, the BRS in VLF was significantly lower after AVP-V1 administration than in base-line condition, while to normotensive rats, the BRS did not change. It indicates that the facilitating effect of AVP on the beroreflex in SIHR is mainly due to V1-receptor in central nerve system. In summary, the transfer function between SBPV and beat-to-beat interval fluctuation could be an index of BRS. This method can be developed for future clinical application.

Animals↗

PubMed1998

Electroretinographic oscillatory potentials in different aged rats: an analysis in the domains of time and frequency.

OBJECTIVES: Electroretinographic Oscillatory Potentials (Ops) are considered to be the optimal parameter to study the retinal circulation disturbances the present we compared parameters of OPs between different aged rats under dark adaptation. METHODS: The scotopic ERG were performed in anaesthetized rats aged 3, 12, 24 months. According a window of collective power spectrum field of the OPs was isolated by using the FFT and IFFT of the spectrum analysis program. The parameters in the time and frequency domains were calculated. RESULTS: Results showed that the amplitudes of wavelets and the summed amplitudes of OPs declined with the increase of age. A reduction of the total power and dominated power of OPs was also found after the FFT. But implicit time of each OP and dominant frequency did not change obviously. CONCLUSIONS: The present study indicated that change of OPs of rat might be related to senile degeneration of the retina and circulative deficiency in retina in elder rats.

Aging↗

PubMed1998

Characterization of an A/T-rich family of sequences from channel catfish (Ictalurus punctatus).

A family of highly repetitive DNA sequences referred to as Xba elements was identified and characterized from the channel catfish (Ictalurus punctatus) genome. The Xba elements represent about 5% to 6% of the total genomic DNA of the channel catfish. The Xba elements are distributed specifically in the channel catfish and blue catfish (I. furcatus), but not in closely related species such as white catfish (Ameiurus catus) and flathead catfish (Pylodictus olivaris). These Xba elements are arranged as head-to-tail tandem repeats. Seven sequences were sequenced. They are A/T-rich (over 65%). Each sequence contains four copies of the ATTA repeat and eight copies of (A)3-6 GT/TG motifs whose function is not known. Each unit of the repeats is 325 bp from the Kansas strain, and 321 pb from the Auburn and Stuttgart strains of channel catfish. The Xba elements are conserved in length within a specific strain, and highly conserved in sequence identity. Sequence identity is more conserved among copies isolated from the same strain than from different strains. The sequence length polymorphism among strains may be useful for identification of strains by polymerase chain reaction analysis. Many features of these elements could make them potentially important for development of homologous recombination expression vectors and position-independent expression vectors.

Adenine↗

PubMed1998

Resurgence of vivax malaria in Henan Province, China.

Henan Province (population, 90 million) in China has nonstable endemic malaria. After 1970 when 10.2 million cases of malaria were reported in the province, a huge control programme was undertaken, and in the mid-1980s indoor spraying and bednet impregnation with pyrethroids began. By 1992 only 318 cases were reported. In 1992 Henan declared "basic elimination of malaria" and in consequence spraying and bednet impregnation ceased after 1994. Subsequently, malaria broke out again in southern Henan. In 1995 we conducted a household survey for malaria transmission in southern Henan. Blood smears and serum samples for immunofluorescent antibody (IFA) testing were collected from 2329 people and 3.1% (73/2329) were positive for infection with Plasmodium vivax and 13% (301/2329) positive for malaria (titre > or = 1:20). All age groups were affected. Exophilic Anopheles sinensis occurs throughout the province; endo-anthropophilic A. anthropophagus, whose vectorial capacity is 20 times greater than that of A. sinensis, occurs mainly in southern Henan (S of latitude 33 degrees N) and was greatly reduced in numbers during 1985-92. Comparison of 1995 entomological data with historical data showed that A. anthropophagus increased in proportion to other anophelines after spraying activities and impregnation of bednets ceased. Over 10% of 9377 residents reported having malaria. The true number affected among the at-risk population of 700,000 must be larger. We conclude that impregnated bednets and malaria surveillance should continue even after an area is declared to have "basically eliminated" malaria.

Adolescent↗

PubMed1998

Angiotensin-(1-7): a novel vasodilator of the coronary circulation.

Angiotensin-(1-7) [Ang-(1-7)] possesses novel biological functions that are distinct from angiotensin II (Ang II). In coronary arteries, the octapeptide Ang II and the heptapeptide Ang-(1-7) exert opposing actions. Ang II elicits vasoconstriction and Ang-(1-7) is a vasodilator. Ang-(1-7) elicits vasodilation by an endothelium-dependent release of nitric oxide. Further, the vasorelaxant activity is markedly attenuated by the bradykinin (BK) B2 receptor antagonist icatibant and does not appear to be associated with the synthesis and release of prostaglandins. Ang-(1-7) vasodilation is mediated by a non-AT1/AT2 receptor, since [Sar1Thr8]-Ang II, but neither candesartan, an AT1 receptor antagonist, nor PD123319, an AT2 receptor antagonist, blocked the response. Specific and high affinity binding of 125I-Ang-(1-7) to the endothelial layer of canine coronary arteries was demonstrated using in vitro emulsion autoradiography. Binding was effectively competed for by either unlabeled Ang-(1-7) or the specific Ang-(1-7) antagonist [D-Ala7]-Ang-(1-7). Additionally, Ang-(1-7) potentiated synergistically BK-induced vasodilation. The EC50 of BK vasodilation (2.45 +/- 0.51 nmol/L vs 0.37 +/- 0.08 nmol/L) was shifted 6.6-fold left-ward in the presence of 2 mumol/L concentration of Ang-(1-7). The potentiated response was specific for BK, since Ang-(1-7) did not augment the vasodilation produced by either acetylcholine or sodium nitroprusside; further, it was specific for Ang-(1-7), since neither Ang I nor Ang II augmented the BK response. In contrast to the vasodilator actions of Ang-(1-7), the potentiated response was not blocked by candesartan, PD123319 or [Sar1Thr8]-Ang II. Novel studies from our group demonstrate that Ang-(1-7) is both a substrate and inhibitor for angiotensin converting enzyme (ACE). Ang-(1-7) was shown to retard the degradation of 125I-[Tyr0]-BK in coronary rings. These studies describe novel actions of Ang-(1-7) as a vasodilator and a local synergistic modulator of kinin-induced vasodilation in coronary arteries.

Angiotensin I↗

PubMed1997

Cytochrome c and dATP-dependent formation of Apaf-1/caspase-9 complex initiates an apoptotic protease cascade.

We report here the purification of the third protein factor, Apaf-3, that participates in caspase-3 activation in vitro. Apaf-3 was identified as a member of the caspase family, caspase-9. Caspase-9 and Apaf-1 bind to each other via their respective NH2-terminal CED-3 homologous domains in the presence of cytochrome c and dATP, an event that leads to caspase-9 activation. Activated caspase-9 in turn cleaves and activates caspase-3. Depletion of caspase-9 from S-100 extracts diminished caspase-3 activation. Mutation of the active site of caspase-9 attenuated the activation of caspase-3 and cellular apoptotic response in vivo, indicating that caspase-9 is the most upstream member of the apoptotic protease cascade that is triggered by cytochrome c and dATP.

Amino Acid Sequence↗

PubMed1997

Retinal 5-methoxytryptamine and 5-methoxyindole-3-acetic acid in the rat and quail: diurnal rhythms and interspecies differences.

Endogenous 5-methoxytryptamine (5MT) and its biosynthetic oxidation product, 5-methoxyindole-3-acetic acid (5MIAA), were successfully identified and measured in the retina of the rat and quail by gas chromatography/electron-capture negative ion chemical ionization mass spectrometry (GC/EC-NICI-MS). In the rat retina, diurnal rhythms of 5MT and 5MIAA, with high levels at mid-light and opposite to that of melatonin, were observed. In the quail, high levels of retinal 5MT and 5MIAA were found at mid-dark, and in phase to that of melatonin. Biosynthetic pathways for retinal 5MT and 5MIAA in the rat and quail were discussed in relation to the diurnal rhythms observed. Our results indicate that the biosynthesis and physiological functions of retinal 5MT and 5MIAA could be species dependent.

5-Methoxytryptamine↗