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Biomedical subjects

B W Li

Publications and source records attributed to B W Li.

At least 19 recordsLinked to original sources
PubMed2001

Adaptation of PMLS neurons to prolonged optic flow stimuli.

Changes in neuronal responses during and after adaptation to prolonged optic flow stimulation were investigated by extracellular single-unit recording in the posteromedial lateral suprasylvian area (PMLS) of the cat. In comparison with translation stimuli, the complex optic flow patterns (radiation and rotation) produced more pronounced adaptation and after-effects by inducing larger response reduction, and altered the direction selectivity of many neurons obviously as well. Generally, the adaptation effects were direction-specific for radiation/rotation, but independent of the direction of test stimulus for translation. These results suggest that PMLS may play an important role in the perception of motion after-effects to complex optic flow fields, while the adaptation to simple translation might be generated at a relatively earlier level of the visual system.

Adaptation, Physiological↗
PubMed2001

Pattern and component motion selectivity in cortical area PMLS of the cat.

Visual motion perception is one of the most prominent functions performed by the mammalian cerebral cortex. The moving images are commonly considered to be processed in two stages. The first-stage neurons are sensitive to the motion of one-dimensional orientated components, and their outputs are combined at the second stage to perceive the global motion of the whole pattern. Alternatively, the pattern motion may be signalled by monitoring a distinctive feature of the image, such as a line-end or a corner. In the present study, a series of 'random-line' patterns were used to measure the direction-tuning responses of 138 neurons in the posteromedial lateral suprasylvian area of the cat. The novel stimuli comprised identical thin line segments, with a length : width ratio no less than 10 : 1, which were moved perpendicularly or obliquely to their common orientation during the recordings. When the component lines were much shorter than the size of receptive field, the majority of cells were selective to the direction of pattern motion while only a small subset was sensitive to the direction of component motion. However, the response profiles of most cells became more component-motion selective with the increment of orientation element in stimulus by elongating the component lines in the patterns. These findings imply that the two-stage theory might be incomplete for modelling the visual motion analysis. Even at relatively low levels of the visual system, some kind of nonorientation-based processing may coexist with the orientation-sensitive processing in a dynamic competition, where one rises as the other falls depending upon the strength of the orientation element in the stimulus, so that under some circumstances it becomes possible to signal the veridical direction of pattern motion.

Action Potentials↗
PubMed2001

[Systemic breeding of the new variety of Biantiao ginseng (Panax ginseng)].

OBJECTIVE: To breed new varieties of Biantiao ginseng for high yield and fine quality. METHODS: Systemic breeding methods were applied. About 3,000 outstanding Biantiao ginseng roots were selected and planted in breeding field, and self-crossed for four generations. During the course, inferior lines or plants were rejected. Then strain comparison, identification of resistance to black-speck disease, and analysis of active compositions were carried out. RESULTS: "Biantiao 1" (BT1), the first new variety of Biantiao ginseng, with green stems and thick, long, elegant roots and median resistance to black-speck disease, has been harvested since 20 years. The percentage of Biantiao ginseng roots and yield were 15% and 30% higher than the control's respectively. The content of total ginsenosides and the main monomers was 1.8%-2.5% higher than the control's. The characteristics of overground part and root of BT1 were uniform and stable. CONCLUSIONS: BT1, a new excellent ginseng variety, has a good potential value to be generalized in ginseng production.

Breeding↗
PubMed2000

A rapid-format antibody card test for diagnosis of onchocerciasis.

Improved methods are needed for field diagnosis of onchocerciasis, to support efforts aimed at elimination of the disease. A rapid-format card test was evaluated that detects IgG4 antibodies to recombinant Onchocerca volvulus antigen Ov16 with serum samples from patients with onchocerciasis and with various types of control serum samples. The sensitivity of the test with serum samples from 106 microfilariae-positive subjects was 90.6%. The test was equally sensitive with serum samples obtained from patients in Africa and Latin America. Specificity was excellent; positive tests were observed for 2 of 38 serum samples from patients with other filarial infections and for 1 of 23 serum samples from patients with nonfilarial helminth infections. The 3 "false-positive" serum samples were from West Africans who could have been coinfected with onchocerciasis. No positive tests were observed with nonendemic serum samples from normal adults, patients with autoimmune disorders, or patients with the hyper-IgE syndrome. This new test holds great promise as a simple tool for diagnosis of onchocerciasis.

Adult↗
PubMed2000

Response properties of PMLS and PLLS neurons to simulated optic flow patterns.

The processing of optic flow information has been extensively investigated in the medial superior temporal area (MST) of the macaque. In the cat, the posteromedial area and the posterolateral area in the lateral suprasylvian cortex (PMLS and PLLS, respectively) have been suggested as likely participants according to their direction preferences to moving objects. In the present study, 203 PMLS and 123 PLLS neurons were tested with simulated optic flow patterns composed of random dots (including expansion and contraction, clockwise and counter-clockwise rotation, and translation) and moving bar stimuli. About 90% of the neurons were found to be excited by the optic flow stimuli and most of them were multiple-responsive to different flow patterns. Only 20-25% of the cells were selective to different optic flow modes, and in general, the direction preference was fairly modest. The selective cells showed stronger directionality to both flow field and moving bar than nonselective cells. However, the optic flow response properties in the PMLS and PLLS were not well correlated with the direction preference to moving bars. In accordance with previous findings, the PMLS was analogous to the middle temporal area of the macaque in many respects. As for the PLLS cells, they were sensitive to fewer types of stimuli, but responded better and more selectively to radial motion. All these results suggest that the two lateral suprasylvian areas are unlikely to be specialized for the analysis or discrimination of different flow patterns, but may play some kind of relay role in optic flow information processing.

Animals↗
PubMed1999

Immune responses to Brugia malayi paramyosin in rodents after DNA vaccination.

Immunization with recombinant Brugia malayi paramyosin protein (BM5) induces partial immunity to this filarial nematode in jirds. The present study examined the effects of intramuscular immunization with plasmid DNA that encodes BM5. DNA-immunized mice produced strong antibody and cell-mediated responses to paramyosin. The protective activity of DNA vaccination with BM5 was tested in jirds. Vaccinated jirds produced strong antibody responses to paramyosin, but adult worm recoveries after challenge were not decreased in vaccinated animals relative to controls. These studies show that DNA vaccination can induce immune responses to filarial antigens in rodents. Further efforts will be needed to achieve the goal of inducing protective immunity to filariasis with this promising new technology.

Animals↗
PubMed1999

Isolation and characterization of the lignans, isolariciresinol and pinoresinol, in flaxseed meal.

The isolation and characterization of the lignans, isolariciresinol, pinoresinol, secoisolariciresinol, and matairesinol, potent phytoestrogens, from flaxseed meal are described. This is the first report of isolariciresinol and pinoresinol being detected in a food. The extraction method selected combined the removal of the lignan glycosides from the plant matrix with an alcoholic solvent system, followed by acid hydrolysis to release the aglycons. A reversed-phase high-performance liquid chromatography with diode array detection system was used for initial separation and detection of the lignans at 280 nm in the acid-hydrolyzed methanolic extract. Lignan trimethylsilyl ether derivatives were characterized by gas chromatography/mass spectrometry. Secoisolariciresinol is the major lignan in flaxseed; isolariciresinol, pinoresinol, and matairesinol were identified as minor lignan components.

Chromatography, High Pressure Liquid↗
PubMed1999

The influence of surgical sites on early postoperative hypoxemia in adults undergoing elective surgery.

UNLABELLED: To determine the influence of the surgical sites on early postoperative hypoxemia, we studied postoperative hypoxemia in 994 patients, ASA physical status I or II, aged 18-68 yr, scheduled for various types of elective surgery. Patients were divided into three groups on the basis of the surgical sites: Group 1 = elective superficial plastic surgery (n = 288); Group 2 = upper abdominal surgery (n = 452); and Group 3 = thoracoabdominal surgery (n = 254). Anesthesia was maintained with 1%-2% enflurane and 67% nitrous oxide in oxygen; thiopental or fentanyl was given IV as required. SpO2 levels were recorded while patients breathed room air shortly after arrival in the recovery room (0 min) and 5, 10, 15, 20, 30, 40, 50, 60, 120, and 180 min thereafter. The results showed that during the early postoperative period, the degree of arterial desaturation and the incidences of hypoxemia (SpO2 86%-90%) and severe hypoxemia (SpO2 85%) were closely related to the operative sites and were greatest for thoracoabdominal operations, less for the upper abdominal operation, and least for the peripheral surgery. The incidence of hypoxemia and severe hypoxemia in the recovery room was 7% and 0.7%, respectively, in Group 1, 38% and 3% in Group 2, and 52% and 20% in Group 3. Mild airway obstruction and hypothermia in the postanesthesia recovery unit (PAR) were the predictive factors of early postoperative hypoxemia. We conclude that during the early postoperative period, there were significant differences in SpO2 levels and incidences of hypoxemia and severe hypoxemia among the three groups. IMPLICATIONS: We found that the severity of arterial desaturation and the incidence of hypoxemia during the early postoperative period are closely related to the surgical sites and are strongest for thoracoabdominal surgery, less for upper abdominal surgery, and least for peripheral surgery.

Abdomen↗
PubMed1997

[Experimental study on effect of shenyi xieli mixture on nature killer cell activity and lymphocyte reactivity to IL-2 in tumor mice].

OBJECTIVE: To explore therapeutic mechanism of Shengyi Xieli Mixture (SYXLM) on malignant tumor. METHODS: Chemotherapy, radiotherapy and different doses of SYXLM were used to treat tumor mice [correction of rats]. RESULTS: SYXLM could enhance the nature killer (NK) cell activities of the tumor mice [correction of rats], and this effect was dose dependent (control group 52.70 +/- 6.01, SYXLM No. 1 group 59.01 +/- 10.00, SYXLM No. 2 group 78.33 +/- 10.90, P < 0.01). The NK cell activities of the tumor mice [correction of rats] were inhibited in the chemotherapy group alone, but they were enhanced in the group of chemotherapy combined with SYXLM (P < 0.05), the results were the same in the radiotherapy group alone and the group of radiotherapy combined with SYXLM (P < 0.05). The response of lymphocyte of the tumor mice [correction of rats] to IL-2 was enhanced significantly in SYXLM group compared with the control group. This response was enhanced insignificantly in the group in which radiotherapy combined with the SYXLM. CONCLUSION: The SYXLM could enhance the function of immune system of the tumor mice [correction of rats] and diminish or reduce the side effect of radiotherapy, chemotherapy to the immune system of the tumor mice [correction of rats].

Animals↗
PubMed1995

Cloning of an early immunodominant filarial antigen: a member of the Brugia malayi myosin heavy chain gene family.

Partial protective immunity to filariasis can be achieved in animals by vaccination with irradiated infective larvae. A Brugia malayi cDNA expression library was screened with serum pools from vaccinated and infected jirds to select clones that expressed potentially protective recombinant antigens that were preferentially recognized by sera from vaccinated animals. Bmmyo-2, the largest of a group of related clones, was studied in detail. Jirds produced strong antibody responses to the protein product of Bmmyo-2, Bmmhc-B, as early as 1 month after vaccination with irradiated larvae. Antibody responses to Bmmhc-B in infected jirds were weaker than those of vaccinated jirds, and they developed somewhat later. Antibodies produced to Bmmhc-B were reactive with a 200 kDa native B. malayi antigen by immunoblot and with muscle bands in the body wall of microfilarial by indirect immunofluorescence. Sequence analysis of the 1454 bp cDNA insert of Bmmyo-2 showed that it codes for a portion of the rod region of a B. malayi myosin heavy chain isoform. The deduced amino acid sequence of Bmmyo-2 is 74.6% identical with that of the corresponding region of Caenorhabditis elegans myosin heavy chain B, but only 64.6% identical with a recently described B. malayi myosin heavy chain, Bmmhc-A.

Amino Acid Sequence↗
PubMed1995

Molecular characterization of a Brugia malayi intermediate filament protein which is an excretory-secretory product of adult worms.

Filarial parasites release macromolecules into their environment both in vitro and in vivo. These excretory-secretory products (E-S) have been studied with respect to function, vaccination potential, pathogenicity, and ability to serve as antigen targets for diagnostic tests. We have recently described monoclonal antibody OV-1 which binds to an intermediate filament in E-S and circulating antigens of Onchocerca volvulus. OV-1 also binds to cross-reactive antigens of Brugia malayi. Therefore, OV-1 was used to immunoscreen a B. malayi adult worm cDNA library in an attempt to clone a homologue (BMIF). BMIF is a 1664-bp full-length transcript which codes for 505 amino acids. BMIF has 95% sequence homology at the amino-acid level to OV1CF, an O. volvulus intermediate filament that was also selected with OV-1, and 75% homology to Ascaris intermediate filament A. Southern blot analysis suggests that BMIF is confined to a single location in the genomic DNA of B. malayi. Antibodies raised to BMIF identified native antigens in immunoblots of B. malayi adult worms, infective larvae and adult E-S. In addition, the antibody also bound to a 60-kDa antigen in immunoblots of poly(ethylene glycol)-precipitated immune complexes in sera from B. malayi infected patients. Localization studies showed that the antigen encoded by BMIF is present in the hypodermis, developing embryos and muscle of adult B. malayi. These studies show that BMIF is an E-S product of B. malayi adult worms which is detectable in sera from patients with brugian filariasis.

Amino Acid Sequence↗
PubMed1994

Molecular cloning of Brugia malayi antigens for diagnosis of lymphatic filariasis.

Immunological crossreactivity among nematodes has hampered development of specific serodiagnostic assays for lymphatic filariasis. In the present study, we report the molecular cloning and characterization of two filaria-specific recombinant clones (BmM5 and BmM14) with immunodiagnostic potential. BmM5 is a 505-bp cDNA which codes for a protein of 130 residues that ends with an endoplasmic reticulum targeting sequence. BmM14 is closely related to a recently reported clone (SXP-1), and it has 62% homology (deduced amino acid sequence) with a previously described Onchocerca volvulus clone, lambda RAL-2. Glutathione S-transferase fusion proteins of BmM5 and BmM14 were tested in various ELISA formats. The best results were obtained by measuring IgG4 antibodies to the fusion proteins. ELISA studies showed that approximately 90% of 111 sera from Indian and Egyptian patients with brugian and bancroftian filariasis were reactive with both antigens. Nonendemic sera as well as sera from patients with schistosomiasis or intestinal helminths were uniformly nonreactive. Assays based on BmM5 and BmM14 may be useful for large scale screening as an alternative to microfilaria or filarial antigen detection as a means of obtaining a rough index of filariasis endemicity in previously unstudied areas.

Amino Acid Sequence↗
PubMed1994

Evidence supporting the presence of Borrelia burgdorferi in Missouri.

Although Lyme disease is commonly seen in the southcentral United States, the epidemiology of the disease is poorly defined there. The purpose of this study was to document the presence of Borrelia burgdorferi in ticks collected in southeastern Missouri and around the city of St. Louis. Spirochetes were detected and identified as B. burgdorferi by immunofluorescent antibody (IFA) tests using the monoclonal antibody H5332 in 1.9% of Amblyomma americanum and 2.0% of Dermacentor variabilis ticks collected. The identity of IFA-positive organisms was verified by polymerase chain reactions (PCRs) with two different sets of B. burgdorferi-specific primers followed by Southern blotting. The DNA sequences of amplified 371-basepair PCR products from two positive Missouri ticks showed 97-98% identity with that obtained by the same method for the B31 strain of B. burgdorferi. These results confirm that B. burgdorferi is present in questing D. variabilis and A. americanum ticks in areas of Missouri where Lyme disease occurs. Additional studies are needed to determine the role of these ticks in the epidemiology of Lyme disease in Missouri and neighboring states.

Animals↗
PubMed1993

Vaccination with recombinant filarial paramyosin induces partial immunity to Brugia malayi infection in jirds.

Vaccination with irradiated infective larvae induces partial protective immunity to infection with the filarial nematode Brugia malayi in jirds. Prior studies have shown that such immunization stimulates a much stronger antibody response to recombinant and native filarial paramyosin than that seen after normal infection. To determine whether vaccination with recombinant paramyosin could induce protective immunity to larval challenge, jirds were immunized with either B. malayi paramyosin and maltose binding protein (BM5-MBP) (fusion protein of B. malayi paramyosin and maltose-binding protein), MBP alone, or recombinant Dirofilaria immitis paramyosin. Animals were challenged with 100 infective larvae s.c. 8 wk after the second immunization. Necropsies were performed 16 wk after challenge. Vaccination with BM5-MBP induced significant protective immunity; adult worm recoveries, worm lengths, and blood microfilaria counts were reduced in the BM5-MBP group relative to the MBP control group. The reductions in adult worm recoveries (43%) and female worm lengths (10%) were statistically significant (p < 0.05). Interestingly, protective immunity was not induced by immunization with D. immitis paramyosin. Additional studies are needed to identify mechanisms involved in protective immunity induced by BM5-MBP and to understand the differential activity of the two closely related recombinant paramyosin proteins in this model.

Animals↗
PubMed1993

[Comparison of the repetitive DNA sequences between Paragonimus westermani and Pagumogonimus skrjabini from six areas].

The genomic DNA of the two lung flukes (P. westermani and P. skrjabini) from six areas was digested separately by three restriction endonucleases BamHI, Hae III and Hind III, followed by agarose gel electrophoresis. Repetitive DNA were visualized as distinct bands in stained gels. Restriction fragment length differences were detected between the two species. The majority of bands of repetitive DNA were similar with minor differences within the same species collected from different areas, upon digestion with certain restriction endonucleases. The results demonstrated that the technique for demonstrating the band pattern of repetitive DNA with three restriction endonucleases can be used for the identification of P. westermani and P. skrjabini and the geographic relationship of the same species from different areas (Figs. 1-3).

Animals↗
PubMed1992

Brugia malayi: antibody responses to larval antigens in infected and immunized jirds.

Vaccination with irradiated third stage Brugia malayi larvae (L3) has been reported to induce partial protective immunity to L3 challenge in jirds. The purpose of this study was to identify antigens that may be targets of protective immunity in this model. Jirds were immunized by s.c. injection of irradiated L3 and challenged either s.c. or i.p. Necropsy was performed 11 wk after challenge. Partial protection was achieved in s.c. challenged animals; worm recovery was only 41% of that observed in unvaccinated controls, and worms recovered from immunized animals were stunted. Worm recoveries in immunized animals that were challenged i.p. did not differ from those of unimmunized controls. Group differences in parasite antigen levels in sera collected 2-11 wk after larval challenge were consistent with parasitological findings obtained at necropsy. Antibody studies compared prechallenge sera from immunized animals to sera from infected (unimmunized) controls. Antibody responses to L3 surface antigens (assessed by IFA) were much stronger after immunization than after infection. Immunoblot studies showed preferential recognition of several L3 antigens (97, 54, 48, and 40 kDa) by antibodies in sera from immunized animals. Additional studies are needed to determine whether immunization with such preferentially recognized antigens can induce protection to larval challenge comparable to or better than that observed with live vaccines.

Animals↗
PubMed1991

Identification of paramyosin as a potential protective antigen against Brugia malayi infection in jirds.

Vaccination of jirds with irradiated infective larvae of Brugia malayi has been reported to provide partial immunity to larval challenge. In the present study, we found that sera from vaccinated animals recognized larval antigens with apparent molecular weights of 97, 55-60, and 10 kDa that were not recognized by sera from infected animals. A B. malayi cDNA expression library in lambda gt11 was screened to identify clones that were preferentially recognized by sera from immunized animals. One of these clones (BM-5) was chosen for further study. BM-5 contains a 2.1 kb DNA insert and produces a fusion protein with a molecular weight of 185 kDa. Antibody, affinity-purified with the BM-5 fusion protein, binds to a 97 kDa native B. malayi antigen. Immunological studies and partial DNA sequence data confirm that BM-5 encodes paramyosin. Recombinant B. malayi paramyosin is strongly recognized by antibodies in sera from jirds that have been immunized either by injection with irradiated larvae or by chemotherapy-abbreviated infection. Most sera from infected jirds do not contain antibody to paramyosin. Additional studies are needed to determine whether paramyosin is actually protective in this filariasis model.

Amino Acid Sequence↗