Biomedical subjects

J L Li

Publications and source records attributed to J L Li.

At least 37 records · Page 2Linked to original sources

PubMed2001

[A control study of personality characteristics and variation of plasma peptide in pilots with neurosis].

Objective. To study the relationship between personality type and variation of plasma peptides in pilots with neurosis. Method. A case-control study was used. 124 male pilots were evaluated with Eysenck's personality checklist, and then level of certain plasma peptides, such as vasoactive intestinal peptide (VIP), beta-endorphin (beta-EP) and angiotensin-II (A-II) were determined. Result. There were significant difference in personality characteristics and personality types between pilots with neuroses and the control. The contents of VIP and beta-EP in plasma showed visible difference between disease group and control. Content of beta-EP in those with inner-unstable type personality was lowest among all the various types. Conclusion. Personality characteristics were different between pilots with neurosis and controls. Levels of VIP and beta-EP in disease group were lower than those in the control. Different personality types had different levels of beta-EP in pilots with neurosis.

Adult↗

PubMed2001

[A comparative study on sterols of ethanol extract and water extract from Hericium erinaceus].

OBJECTIVE: To study the pharmaceutic chemical basis of the different medicinal effects, and to compare and analyze the sterols in Hericium erinaceus mycelia and its ethanol extract, water extract derived from solid fermented mycelia. METHOD: The components of Hericium erinaceus mycelia and two kinds of extract were compared with some biochemical methods such as GC, RP-HPLC, etc. Sterol composition in Hericium erinaceus mycelia was determined by using GC-mass spectrometry. RESULTS: The content of crude polysaccharide, water-soluble protein and fatty acid of ethanol extract showed no obvious advantage over its water extract. However, there was significant difference between two kinds of extract in the content of sterols. And ergostane derivatives, beta-sitosterol and C28 sterol with four bonds were detected as the major sterols in Hericium erinaceus mycelia, among which ergosterol was the principal sterol. CONCLUSION: Sterols in Hericium erinaceus exist mainly in ethanol extract. And three sterols are found for the first time from Hericium erinaceus, which are ergostane derivatives, beta-sitosterol and C28 sterol with four bonds.

Basidiomycota↗

PubMed2001

[Pattern recognition of stereoscopic features of the leaves epidermis of medicinal Curcuma plants in China by image analysis].

OBJECTIVE: To provide new ways for classifying and identifying medicinal curcuma plants. METHOD: Based on classical taxonomy, the microscopic features of the epidermis of Curcuma plants in China were scored quantitatively by stereology and image analysis. RESULT: It showed that there were a lot of differences in density, size and shape of the epidermic cells among the medicinal Curcuma plants in China; that the average perimeter of the upper epidermic cells, average sectional area of the lower epidermis, stoma density and trichoma distribution of the upper and lower epidermis, etc. could be considered to be the main evidences for the microscopic identification of leaves of Curcuma. The 21 materials which belong to 11 species of Curcuma in China were systematized into 6 species, 1 species complex, 2 cultivated varieties. CONCLUSION: It can be concluded that stereology, and image analysis are advanced and feasible in pharmacognosy and taxonomy especially in the authentication of the relative and easily confused species.

Curcuma↗

PubMed2000

Cyclosporine A-induced hypertension involves synapsin in renal sensory nerve endings.

The calcineurin inhibitor cyclosporine A (CsA) has emerged as a major cause of secondary hypertension in humans, but the underlying pathogenetic mechanisms have remained enigmatic. Synapsins are a family of synaptic vesicle phosphoproteins that are essential for normal regulation of neurotransmitter release at synapses. In addition to synaptic vesicles, synapsins and other vesicle proteins are found on microvesicles in sensory nerve endings in peripheral tissues. However, the functions of the sensory microvesicles in general, and of synapsins in particular, are unknown. We now demonstrate in a mouse model that CsA raises blood pressure by stimulating renal sensory nerve endings that contain synapsin-positive microvesicles. In knockout mice lacking synapsin I and II, sensory nerve endings are normally developed but not stimulated by CsA whereas a control stimulus, capsaicin, is fully active. The reflex activation of efferent sympathetic nerve activity and the increase in blood pressure by CsA seen in control are greatly attenuated in synapsin-deficient mice. These results provide a mechanistic explanation for CsA-induced acute hypertension and suggest that synapsins could serve as a drug target in this refractory condition. Furthermore, these data establish evidence that synapsin-containing sensory microvesicles perform an essential role in sensory transduction and suggest a role for synapsin phosphorylation in this process.

Afferent Pathways↗

PubMed2000

Replication protein A physically interacts with the Bloom's syndrome protein and stimulates its helicase activity.

Bloom's syndrome is a rare autosomal recessive disorder characterized by genomic instability and predisposition to cancer. BLM, the gene defective in Bloom's syndrome, encodes a 159-kDa protein possessing DNA-stimulated ATPase and ATP-dependent DNA helicase activities. We have examined mechanistic aspects of the catalytic functions of purified recombinant BLM protein. Through analyzing the effects of different lengths of DNA cofactor on ATPase activity, we provide evidence to suggest that BLM translocates along single-stranded DNA in a processive manner. The helicase reaction catalyzed by BLM protein was examined as a function of duplex DNA length. We show that BLM catalyzes unwinding of short DNA duplexes (</=71 base pairs (bp)) but is severely compromised on longer DNA duplexes (>/=259-bp). The presence of the human single-stranded DNA-binding protein (human replication protein A (hRPA)) stimulates the BLM unwinding reaction on the 259-bp partial duplex DNA substrate. Heterologous single-stranded DNA-binding proteins fail to stimulate similarly the helicase activity of BLM protein. This is the first demonstration of a functional interaction between BLM and another protein. Consistent with a functional interaction between hRPA and the BLM helicase, we demonstrate a direct physical interaction between the two proteins mediated by the 70-kDa subunit of RPA. The interactions between BLM and hRPA suggest that the two proteins function together in vivo to unwind DNA duplexes during replication, recombination, or repair.

Adenosine Triphosphatases↗

PubMed2000

gamma-aminobutyric acid- and glycine-immunoreactive neurons postsynaptic to substance P-immunoreactive axon terminals in the superficial layers of the rat medullary dorsal horn.

gamma-Aminobutyric acid (GABA)ergic and glycinergic neurons were examined light- and electron-microscopically in laminae I and II of the medullary dorsal horn (MDH, i.e. spinal trigeminal nucleus caudalis in the rat). The majority of GABA- and glycine (Gly)-immunoreactive (-ir) neurons showed both GABA- and Gly-immunoreactivities (-IRs). Noxious stimulation (subcutaneous injection of formalin into perioral regions) induced Fos-IR in some of GABA- and Gly-ir neurons. GABA- and Gly-ir neuronal profiles were postsynaptic to substance P-ir axon terminals. These results suggest that nociceptive information being carried by primary afferent SP-fibers may be relayed directly to GABAergic and glycinergic neurons in laminae I and II of the MDH.

Animals↗

PubMed2000

Guanylyl cyclase activity associated with putative bifunctional integral membrane proteins in Plasmodium falciparum.

We report here that guanylyl cyclase activity is associated with two large integral membrane proteins (PfGCalpha and PfGCbeta) in the human malaria parasite Plasmodium falciparum. Unusually, the proteins appear to be bifunctional; their amino-terminal regions have strong similarity with P-type ATPases, and the sequence and structure of the carboxyl-terminal regions conform to that of G protein-dependent adenylyl cyclases, with two sets of six transmembrane sequences, each followed by a catalytic domain (C1 and C2). However, amino acids that are enzymatically important and present in the C2 domain of mammalian adenylyl cyclases are located in the C1 domain of the P. falciparum proteins and vice versa. In addition, certain key residues in these domains are more characteristic of guanylyl cyclases. Consistent with this, guanylyl cyclase activity was obtained following expression of the catalytic domains of PfGCbeta in Escherichia coli. In P. falciparum, expression of both genes was detectable in the sexual but not the asexual blood stages of the life cycle, and PfGCalpha was localized to the parasite/parasitophorous vacuole membrane region of gametocytes. The profound structural differences identified between mammalian and parasite guanylyl cyclases suggest that aspects of this signaling pathway may be mechanistically distinct.

Amino Acid Sequence↗

PubMed2000

The Bloom's syndrome gene product promotes branch migration of holliday junctions.

Bloom's syndrome (BS) is an autosomal recessive disorder associated with dwarfism, immunodeficiency, reduced fertility, and elevated levels of many types of cancer. BS cells show marked genomic instability; in particular, hyperrecombination between sister chromatids and homologous chromosomes. This instability is thought to result from defective processing of DNA replication intermediates. The gene mutated in BS, BLM, encodes a member of the RecQ family of DExH box DNA helicases, which also includes the Werner's syndrome gene product. We have investigated the mechanism by which BLM suppresses hyperrecombination. Here, we show that BLM selectively binds Holliday junctions in vitro and acts on recombination intermediates containing a Holliday junction to promote ATP-dependent branch migration. We present a model in which BLM disrupts potentially recombinogenic molecules that arise at sites of stalled replication forks. Our results have implications for the role of BLM as an anti-recombinase in the suppression of tumorigenesis.

Adenosine Triphosphatases↗

PubMed2000

Co-existence of calcium-binding proteins in neurons of the medullary dorsal horn of the rat.

Double immunofluorescence histochemistry for calcium-binding proteins was performed in the caudal subnucleus of the rat spinal trigeminal nucleus; for calbindin D28k (CB) and calretinin (CR), for CB and parvalbumin (PV), and for CB and CR. CB-immunoreactive (-ir) neurons were seen 1.7 times more frequently than CR-ir neurons and 5.5 times more frequently than PV-ir neurons. About 70-90% of these neurons were distributed in substantia gelatinosa. Co-existence of CB and CR was indicated in 2.3% of CB-ir and 3.9% of CR-ir neurons. Co-existence of CB and PV was indicated in 1.0% of CB-ir and 5.5% of PV-ir neurons. Co-existence of CR and PV was indicated in 1.4% of CR-ir and 5.1% of PV-ir neurons. In these doubly immunostained neurons, 59.5-69.5% were observed in substantia gelatinosa, 5.9-17.8% in the marginal zone, and 12.7-31.0% in the magnocellular part.

Animals↗

PubMed2000

[Comparative study of pulmonary magnetic resonance angiography (MRA)].

Imaging was performed using a 1.0 Tesla superconducting MR system with a body coil. Two-dimensional(2D) turbo FLASH sequence and/or three-dimensional(3D) FISP sequence were carried out in 46 volunteers with 113 pulmonary MRA. The total MRAs were divided into 4 groups and analysed. The results showed: After Gd-DTPA was injected, the signal-to-noise ratio(SNR) of pulmonary 2D- and 3D-TOF MRA was increased in 46 normal pulmonary MR angiography cases(P < 0.01); the number of left and right pulmonary artery divisions identified was much greater than that before Gd-DTPA injection both in 2D- and 3D-MOF(except lingual segment of left lobe). It is suggested that Gd-DTPA may markedly promote the efficiency of pulmonary MRA.

Adolescent↗

PubMed2000

Sexual stage-specific expression of a third calcium-dependent protein kinase from Plasmodium falciparum.

A third calcium-dependent protein kinase (CDPK) gene has been isolated from the human malaria parasite Plasmodium falciparum by vectorette technology. The gene consists of five exons and four introns. The open reading frame resulting from removal of the four introns encodes a protein of 562 amino acid residues with a predicted molecular mass of 65.3 kDa. The encoded protein, termed PfCDPK3, consists of four distinct domains characteristic of a member of the CDPK family and displays the highest homology (46% identity and 69% similarity) to PfCDPK2, the second CDPK of P. falciparum. The N-terminal variable domain is rich in serine/threonine and lysine and contains multiple consensus phosphorylation sites for a range of protein kinases. The catalytic domain possesses all conserved motifs of the protein kinase family except for the highly conserved glutamic acid residue in subdomain VIII, which is replaced by a glutamine residue. The sequence of the junction domain comprising 31 amino acid residues is less conserved. The calmodulin-like regulatory domain contains four EF-hand calcium-binding motifs, each consisting of a loop of 12 amino acid residues which is flanked by two alpha-helices. Southern blotting of genomic DNA digests showed that the Pfcdpk3 gene is present as a single copy per haploid genome. A 2900 nucleotide transcript of this gene is expressed specifically in the sexual erythrocytic stage, indicating that PfCDPK3 is involved in sexual stage-specific events. It is proposed that PfCDPK3 may serve as a link between calcium and gametogenesis of P. falciparum.

Amino Acid Sequence↗

PubMed2000

Relationship between neurokinin-1 receptor and substance P in the striatum: light and electron microscopic immunohistochemical study in the rat.

The synaptic relationship between substance P (SP) and its receptor, i.e., neurokinin-1 receptor (NK1R), was examined in the striatum of the rat by confocal laser-scanning microscopy and electron microscopy. For confocal laser-scanning microscopy, triple-immunofluorescence histochemistry was performed to label NK1R, SP, and vesicular acetylcholine transporter (a specific marker for cholinergic neurons). In electron microscopic double-immunolabeling study, immunoreactivity for NK1R was detected with the silver-intensified gold method, while immunoreactivity for SP was detected with peroxidase immunohistochemistry. Simultaneous immunolabeling of NK1R and SP revealed significant mismatch at the synaptic level: although some SP-immunopositive axon terminals were in synaptic contact with NK1R-immunopositive sites of plasma membrane, NK1R-immunoreactivity was observed at both synaptic and non-synaptic sites of plasma membrane. Thus, SP released from the sites remote from NK1Rs might diffuse in the extracellular fluid to act, as a paracrine neurotransmitter, on NK1Rs distant from its releasing site. SP neurotransmission in the striatum might occur not only synaptically but also extrasynaptically. The SP-NK1R system might constitute an association system within the striatum.

Animals↗

PubMed2000

Molecular cloning of a gene encoding a 20S proteasome beta subunit from Plasmodium falciparum.

A novel gene was cloned from Plasmodium falciparum. Database searches indicated this gene to be a member of the 20S proteasome beta-subunit family. Comparison of the gene's genomic DNA sequence with cDNA sequence revealed a 156-bp intron 85 bp downstream from the start codon. The nucleotide sequence of the gene contains one open reading frame encoding 265 amino acids with a predicted molecular mass of 30.9 kDa and a pI of 6.2. Northern blot analysis showed the transcript size to be approximately 1.6 kb indicating that some 800 bp of the transcript is non-coding.

Adenosine Triphosphatases↗

PubMed2000

The relationship between neurokinin-1 receptor and substance P in the medullary dorsal horn: a light and electron microscopic immunohistochemical study in the rat.

The synaptic relationship between substance P (SP) and its receptor, i.e. neurokinin-1 receptor (NK1R), was examined in the superficial laminae of the caudal subnucleus of the spinal trigeminal nucleus (medullary dorsal horn; MDH) of the rat. For confocal laser-scanning microscopy, double-immunofluorescence histochemistry for NK1 and SP was performed. In electron microscopic double-immunolabeling study, immunoreactivity for NK1R was detected with the silver-intensified gold method, while immunoreactivity for SP was detected with peroxidase immunohistochemistry. SP-immunoreactive axon terminals were observed to be in synaptic (mostly asymmetric) contact with NK1R-immunoreactive neuronal profiles in lamina I and lamina IIo. Although some SP-immunoreactive axon terminals were in synaptic contact with NK1R-immunoreactive sites of plasma membranes, NK1R-immunoreactivity was observed at both synaptic and non-synaptic sites of plasma membrane. Thus, SP released from axon terminals might not only act on NK1Rs facing the SP-containing axon terminals, but also diffuse in the extracellular fluid for distances larger than the synaptic cleft to act on NK1Rs at some distances from the synaptic sites.

Animals↗

PubMed2000

Monoclonal antibody against Mycoplasma fermentans-specific aminoglycoglycerolipid.

Previously, we reported that Mycoplasma fermentans has specific antigens (phosphocholine-containing glycoglycerolipids: GGPL-I and GGPL-III) and discussed the possibility of their pathogenic role. In this paper, we report the characterization of a monoclonal antibody (MF-III-1) specific to GGPL-III (phosphocholine-containing aminoglycoglycerolipid) using methods of electron microscopy, immunofluorescence cell surface staining, laser scanning microscopy, immunoelectron microscopy, and thin-layer chromatography immunostaining. The MF-III-1 antibody specifically recognized M. fermentans attached to the surface of HTLV-I-infected human helper T-cells, and it did not cross-react with other lipids nor with human T-cell antigens. Since MF-III-1 distinguishes GGPL-III from GGPL-I, the binding site may include a serinol (2-amino-1,3-propanediol) residue of GGPL-III. MF-III-1 is useful for the in vitro study of M. fermentans, and may also be useful as a tool for the study of the involvement of M. fermentans in human diseases.

Animals↗

PubMed2000

Association of estrogen receptor-alpha genotypes with body mass index in normal healthy postmenopausal Caucasian women.

Several lines of evidence suggest the importance of the estrogen receptor (ER) in determining body mass index (BMI). Our purpose was to investigate whether genetic polymorphisms at the restriction enzyme PvuII site of the ER-alpha gene locus are associated with BMI variation. Data on BMI, age, and ER-alpha genotypes were obtained from 108 healthy midwestern U.S. postmenopausal Caucasian women. The study subjects were unrelated and aged 65 yr and over (mean age +/- SD, 73.4 +/- 5.1 yr), with an average BMI of 25.25 (SD, 4.04). The ER-alpha genotypes were obtained by PCR followed by restriction enzyme PvuII digestion. We found that in our study subjects the ER-alpha genotypes are significantly associated with BMI (by ANOVA, P = 0.04), explaining about 6.2% of the BMI variation in our study sample. The allelic effects of this locus on BMI are approximately additive. In our sample, individuals of the PP and Pp genotypes have, respectively, 11.4% and 4.8% higher BMI than individuals of the pp genotype. There is a significant ER-alpha genotype by age interaction, so that in our sample PP individuals tend to gain weight with age, whereas Pp and pp individuals tend to lose weight with age. Therefore, the ER-alpha polymorphisms are associated with BMI variation in healthy postmenopausal Caucasian women aged 65 yr and over. Our result is consistent with some recent findings suggesting the potential effects of the ER on BMI. The importance of the ER-alpha genotypes in other populations and other age groups needs to be demonstrated. Although the results of the ER-alpha genotype by age interaction are obtained here from cross-sectional data, direct confirmation may come from longitudinal studies in which individuals are measured multiple times over several years. The importance of the ER-alpha genotypes on BMI should be confirmed by further studies using methods robust to the potential problem of population substructuring that may confound the conclusions of population association studies.

Aged↗

PubMed2000

Genetic determination of Colles' fracture and differential bone mass in women with and without Colles' fracture.

Osteoporotic fractures (OFs) are a major public health problem. Direct evidence of the importance and, particularly, the magnitude of genetic determination of OF per se is essentially nonexistent. Colles' fractures (CFs) are a common type of OF. In a metropolitan white female population in the midwestern United States, we found significant genetic determination of CF. The prevalence (K) of CF is, respectively, 11.8% (+/- SE 0.7%) in 2471 proband women aged 65.55 years (0.21), 4.4% (0.3%) in 3803 sisters of the probands, and 14.6% (0.7%) in their mothers. The recurrence risk (K0), the probability that a woman will suffer CF if her mother has suffered CF is 0.155 (0.017). The recurrence risk (Ks), the probability that a sister of a proband woman will suffer CF given that her proband sister has suffered CF is 0.084 (0.012). The relative risk lambda (the ratio of the recurrence risk to K), which measures the degree of genetic determination of complex diseases such as CF, is 1.312 (0.145; lambda 0) for a woman with an affected mother and 1.885 (0.276; lambda s) for a woman with an affected sister. A lambda-value significantly greater than 1.0 indicates genetic determination of CF. The terms lambda 0 and lambda s are related to the genetic variances of CF. These parameters translate into a significant and moderately high heritability (0.254 [0.118]) for CF. These parameters were estimated by a maximum likelihood method that we developed, which provides a general tool for characterizing genetic determination of complex diseases. In addition, we found that women without CF had significantly higher bone mass (adjusted for important covariates such as age, weight, etc.) than women with CF.

Absorptiometry, Photon↗

PubMed2000

[Selection of high avermectins producing strain and identification of avermectin B1].

Three types of colony, powdery gray, white and bald, were isolated from Streptomyces avermitilis ATCC31272. Among them, only the powdery grey one produces avermectins. Sa-76 strain was selected from the powdery grey strain by mutation with high energy electric flow, and its avermectins titer attainde 100 micrograms/mL in shaking flask. Avermectin B1 was extracted and purified from the mycelia of Sa-76, and identified by UV, IR, 1H-NMR, 13C-NMR and mass spectra. After Sa-76 strain was treated twice with NTG, a strain named Sa-76-8 was selected with avermectins titer over 2000 micrograms/mL. The Sa-76-8 strain was treated with NTG once again, and a high avermectins producing strain named as Sa-76-9 with avermectins titer up to 3500-4000 micrograms/mL was selected.

Anthelmintics↗