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Biomedical subjects

J Zhao

Publications and source records attributed to J Zhao.

At least 577 records · Page 32Linked to original sources
PubMed1996

Radioimmunoscintigraphy of gastric adenocarcinomas with 99mTc-chimeric ccM4 antibody.

Fourteen patients with gastric lesions were studied for radioimmunoscintigraphy using the 99mTc-ccM4 chimeric antibody reactive with the human tumor-associated TAG72 antigen. These include 10 gastric adenocarcinomas, 3 gastric ulcers and 1 gastric lymphoma. Each patient received an infusion of 30-40 mCi 99mTc-ccM4 antibody. Gamma camera scans were performed at 12-h postadministration. All patients underwent operation after radioimmunoscintigraphy. All surgical specimens including gastric adenocarcinomas, lymphoma and ulcers were confirmed by histopathological studies. The 99mTc-ccM4 antibody was able to detect 6 out of 10 gastric adenocarcinomas (60%) by scans. Its accuracy was even 5 out of 6 (83%) in a group of patients with well/moderately-differentiated adenocarcinomas. In addition to the primary adenocarcinomatous lesions, the 99mTc-ccM4 antibody was also able to detect metastatic lesions in liver and lymph nodes. The smallest adenocarcinomatous lesion detected by scans was about 1 x 1 x 2 cm3. All four patients with gastric ulcers or lymphoma showed negative scan results. Therefore, the chimeric ccM4 antibody may be useful in radioimmunoscintigraphy of gastric adenocarcinomas, especially the well/moderately-differentiated adenocarcinomas.

Adenocarcinoma↗
PubMed1996

Characterization of cauliflower mosaic virus (CaMV) resistance in virus-resistant ecotypes of Arabidopsis.

Two Arabidopsis ecotypes are resistant to systemic infection by cauliflower mosaic virus (CaMV), a plant para-retrovirus. Arabidopsis ecotype Enkheim-2 (En-2) is highly resistant to CaMV infection while Bla-14 is more weakly resistant. CaMV resistance in En-2 can be largely attributed to the action of a single semidominant gene called cauliflower mosaic virus resistance1 (CAR1), located at a locus on chromosome 1. Resistance in Bla-14 is tightly linked to CAR1 and may be due to a weak allele at the same locus or another gene in a gene cluster. A quantitative polymerase chain reaction assay in conjunction with replication- and movement-incompetent viral mutants was used to determine whether virus replication or movement is affected in the resistant ecotypes. The pattern of accumulation of the wild-type virus in the resistant ecotype, En-2, was similar to that of a movement-incompetent CaMV mutant, suggesting that CAR1 interferes with or fails to support CaMV movement. CaMV-inoculated En-2 plants do not show visible signs of a hypersensitive response. However, indicators of an induced defense response do appear in CaMV-infected En-2 plants, such as the activation of pathogenesis-related protein gene expression and the production of camalexin, an Arabidopsis phytoalexin. Defense responses induced chemically or by mutation in the susceptible ecotypes delayed and reduced the severity of a CaMV infection. These findings suggest that CAR1 acts either in the susceptible ecotype to support virus movement or in the resistant ecotype to signal a defense response.

Arabidopsis↗
PubMed1996

Coordinate regulation of the tryptophan biosynthetic pathway and indolic phytoalexin accumulation in Arabidopsis.

Little is known about the mechanisms that couple regulation of secondary metabolic pathways to the synthesis of primary metabolic precursors. Camalexin, an indolic secondary metabolite, appears to be the major phytoalexin in Arabidopsis. It was previously shown that camalexin accumulation is caused by infection with plant pathogens, by abiotic elicitors, and in spontaneous lesions in the accelerated cell death mutant acd2. We demonstrate that the accumulation of this phytoalexin is accompanied by the induction of the mRNAs and proteins for all of the tryptophan biosynthetic enzymes tested. A strong correlation was observed between the magnitude of camalexin accumulation and the induction of tryptophan biosynthetic proteins, indicating coordinate regulation of these processes. Production of disease symptoms is not sufficient for the response because systemic infection with cauliflower mosaic virus or cucumber mosaic virus did not induce the tryptophan pathway enzymes or camalexin accumulation. Salicylic acid appears to be required, but unlike other documented pathogenesis-related proteins, it is not sufficient for the coordinate induction. Results with trp mutants suggest that the tryptophan pathway is not rate limiting for camalexin accumulation. Taken together, these results are consistent with the hypothesis that the regulation of the tryptophan pathway in plants responds to needs for biosynthesis of secondary metabolites.

Arabidopsis↗
PubMed1996

Opioid receptor affinity of multivalent ligand system consisting of polymerized liposome.

A multivalent ligand system, in which enkephalin/phospholipid conjugates were immobilized on a polymerized liposome, has been prepared. A hydrophilic spacer chain, -(Sar-Sar-Pro)2-, was placed between Tyr-D-Ala-Gly-Trp-Leu (an enkephalin part) and a phospholipid part to diminish steric hindrance of the liposome against receptor binding of the enkephalin unit. The affinity of the immobilized enkephalin conjugate for opioid receptor was dependent on the density of the enkephalin unit on the surface of polymerized liposome, indicating that more than two enkephalin units on a liposome simultaneously bind to receptors in the membrane. IC50 values for the delta- and mu-receptors were 15 and 26 nM, respectively, when the conjugate was immobilized at the molar ratio of [enkephalin]/[phospholipid] of 340. The latter affinity is better than that of Tyr-D-Ala-Gly-Trp-Leu (50 nM). The enkephalin part was located at the membrane surface, as indicated by fluorescence spectroscopy. When 12% cerebroside sulfate was mixed in the polymerized liposome, delta-receptor affinity of the immobilized enkephalin conjugate was improved to 7.4 nM. The environment around the enkephalin part became hydrophilic upon incorporation of cerebroside sulfate into the polymerized liposome, resulting in changes in the receptor affinities.

Animals↗
PubMed1996

Cyclic AMP-dependent anion secretion in human small and large intestine.

Cyclic AMP-dependent Cl- secretion is the major secretion pathway in human intestine. The aim of the present study was to examine mechanisms involved in cAMP-dependent anion secretion in human small and large intestine. Surgical resection specimens from both jejunum and distal colon were studied under short circuited conditions. Addition of the phosphodiesterase inhibitor IBMX induced an increase in the short-circuit current (Isc) equivalent to the net increase in Cl- secretion. The Isc was inhibited by diphenylamine decarboxylate (DPC; Cl- channel blocker), bumetanide (basolateral Na+/K+/2Cl- cotransporter), BaCl2 (basolateral K+ channel) and Cl- free buffer in both segments and indomethacin (cyclo-oxygenase inhibitor) in colon alone. Diphenylamine decarboxylate appears to directly inhibit secretion in jejunum, although its inhibitory effect is possibly mediated by inhibition of cyclo-oxygenase in the colon. A small component of IBMX-stimulated Isc was inhibited by acetazolamide. Cyclic AMP-dependent secretion is largely apical Cl- secretion, although a small component appears to be HCO3. Secretion is dependent on basolateral K+ channels and Na+/K+/2Cl- cotransporters and, in the colon, is inhibited by indomethacin, implying a role for cyclo-oxygenase metabolites. The chloride channel blocker DPC inhibits secretion in both areas. This class of compounds may have potential for treatment of secretory diarrhoea.

Adolescent↗
PubMed1996

Characterization of psaI and psaL mutants of Synechococcus sp. strain PCC 7002: a new model for state transitions in cyanobacteria.

The psaI and psaL genes were characterized from the cyanobacterium Synechococcus sp. strain PCC 7002. The gene organization was different from that reported for other cyanobacteria with psaI occurring upstream and being divergently transcribed from the psaL gene. Mutants lacking PsaI or PsaL were generated by interposon mutagenesis and characterized physiologically and biochemically. Mutant strains PR6307 (delta psaI), PR6308 (psaI-) and PR6309 (psaL-) had doubling times similar to that of the wild type under both high- and low-intensity white light, but all grew more slowly than the wild type in green light. Only monomeric photosystem I (PS I) complexes could be isolated from each mutant strain when Triton X-100 was used to solubilize thylakoid membranes; however, approximately 10% of the PS I complexes from the psaI mutants, but not the psaL mutant, could be isolated as trimers when n-dodecyl beta-D-maltoside was used. Compositional analyses of the mutant PS I complexes indicate that the presence of PsaL is required for trimer formation or stabilization and that PsaI plays a role in stabilizing the binding of both PsaL and PsaM to the PS I complex. Strain PR6309 (psaL-) was capable of performing a state 2 to state 1 transition approximately three times more rapidly than the wild type. Because the monomeric PS I complexes of this mutant should be capable of diffusing more rapidly than trimeric complexes, these data suggest that PS I complexes rather than phycobilisomes might move during state transitions. A "mobile-PS I" model for state transitions that incorporates these ideas is discussed.

Amino Acid Sequence↗
PubMed1996

Detection of hepatitis C virus by PCR in second-generation enzyme immunoassay-seropositive blood donors by using matched pairs of fresh frozen plasma and pilot tube sera.

Between April 1993 and March 1995, 429 of 334,454 (0.13%) blood donations at the Toronto Centre of the Canadian Red Cross were reactive for hepatitis C virus (HCV) by second-generation enzyme immunoassay (EIA-2). Of the 429 EIA-2-positive donations, 189 (44%), 138 (32%), and 102 (24%) were positive, indeterminate, and negative by Second-Generation Recombinant Immunoblot Assay (RIBA-2). To assess HCV viremia and minimize the risk that specimen handling affected PCR-based detection, the qualitative AMPLICOR HCV test was performed on both pilot tube sera (PTS) and the corresponding fresh frozen plasma (FFP) from 294 EIA-2-reactive donations. AMPLICOR PCR results for PTS and FFP were 100% concordant and were confirmed by nested HCV PCR for 27 of 294 donations. The AMPLICOR HCV test was positive for 127 of 140 (91%) of RIBA-2-positive donations (81, 91, and 96% of donations with two, three, and four reactive bands, respectively), 5 of 88 (5.7%) indeterminate donations, and 0 of 66 (0%) RIBA-2-negative donations. The Third-Generation Recombinant Immunoblot Assay (RIBA-3) was performed on RIBA-2-negative, -indeterminate, and -positive, PCR-negative donations. RIBA-3 demonstrated enhanced specificity and resolved 18 of 88 (20%) of RIBA-2-indeterminate samples as HCV antibody positive. The study demonstrates that PTS are as suitable as FFP for PCR-based detection of HCV and can be used to determine if EIA-2-reactive blood donors are viremic at the time of donation.

Blood Donors↗
PubMed1996

Characteristics and mechanisms of the effects of heart rate history on transient AV nodal responses.

The characteristics and functional origin of the changes in transient atrioventricular (AV) nodal responses with heart rate history were studied in isolated rabbit heart preparations. For this purpose, ramp stimulation sequences were applied to the atrium from different initial conditions. A ramp decrease and increase in the His-stimulus interval and a reverse sequence consisting of a ramp increase and decrease were performed starting from a control basic cycle length, after 5 min of fast rate, or with 5 min of fast rate inserted between the two ramps. The nodal conduction times (NCT) obtained during the ramp stimulations formed hysteresis loops, the direction, shape, and magnitude of which varied markedly with the nodal history. That is, the nodal response to a given ramp took a variety of forms, depending on the initial condition. The effects of the initial condition also depended on ramp direction and sequence. A paradoxical NCT-recovery relationship (decrease in NCT with shortening His-atrial interval) was consistently observed at the onset of any ramp decrease performed after 5 min of fast rate. These effects also varied with the rate used to change the nodal history. The insertion of a control cycle at every 20th beat during repeated ramp protocols allowed the determination of the contribution of the nodal property of fatigue to these effects. Fatigue was found to account for all observed hysteresis patterns. In conclusion, heart rate history can, by modulating beat-to-beat changes in fatigue, transform transient nodal responses and hysteresis observed during stimulation ramps. Interpretation of transient nodal responses thus requires exact knowledge of previous nodal history.

Animals↗
PubMed1996

Craniotomy guidance using a stereo-video-based tracking system.

In open intracranial neurosurgery, it is desirable to minimize exposure and to approach the target in the most accurate way possible. The VISLAN system described here employs a completely passive hand-held locator which is tracked by a video system and does not require a mechanical linkage nor cables. The system also tracks easily recognizable, constant, anatomical landmarks of the patient. By this means the initial registration of pre-operative imaging and the detection of, and correction for, patient movement can be accomplished. High-resolution MRI segmented interactively is used to define external surface and brain anatomy. Thus, a pre-operative patient representation (POPR) is planned. During the surgical procedure the patient's head is illuminated by structured light and stereo-video pictures obtained from two television cameras mounted above the head. The system is calibrated and registered with the POPR using a chamfered matching algorithm. The locator is also tracked in space by the video system, and its tip position shown in relation to the POPR on the video monitor.

Craniotomy↗
PubMed1996

Nonhypercalcemic vitamin D analogs: interactions with the vitamin D-binding protein.

The natural vitamin D hormone, 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25-(OH)2D3), not only regulates serum and bone calcium homeostasis but is probably also a paracrine factor in several cells and tissues including skin, immune system, placenta and brain, where it stimulates cell differentiation and inhibits cell proliferation. Several structural analogs of 1 alpha, 25-(OH)2D3 not only have superagonist activity but also display a selective action profile: indeed they maintain or have increased activity on cell differentiation/proliferation but also have substantially decreased calcemic activity when compared to 1 alpha,25-(OH)2D3. This decreased calcemic activity is partially due to mere pharmacological reasons: because of low binding affinity for the plasma vitamin D-binding protein, a more rapid extracellular metabolism and increased cellular uptake is possible when compared to 1 alpha,25-(OH)2D3. Their short extracellular half-life combined with comparable or enhanced transactivation potency together with analog-and cell-type-specific intracellular metabolism can probably explain why some analogs have a unique combination of superagonist activity and specific action profile with favorable dissociation of differentiation versus calcemic potency.

Animals↗
PubMed1996

Cataract free zone and primary health care approach to prevention of blindness in Shunyi county of Beijing.

OBJECTIVE: To establish a three-level eye care network, together with a referral and monitor system for the prevention of blindness, with the aim of creating a cataract free zone. SUBJECTS AND METHODS: Shunyi County with a population of 548364 was chosen as the target site. Our activities included (1) establishment of a County Guiding Committee for the prevention of blindness: (2) training local ophthalmologists and primary eye care personnel: (3) extensive publicity of knowledge for the prevention of blindness: (4) screening for blindness and low vision, (5) cataract surgery as the chief measure for creating a cataract free zone. RESULTS: A referral and monitor system for cataract blindness was established in 1987. Seven local ophthalmologists, 449 primary eye care health workers and six optometrists were trained. 815 cataract-blind patients were identified. Up to December 1991, 667 patients (737 eyes), accounting for 81.84% of the total, were treated with cataract surgery, 90.64% of these eyes had their sight restored, and 59.66% patients resumed work. A cataract free zone has been created in Shunyi County. CONCLUSIONS: The prevention of blindness with cataract surgery as the chief measure can dramatically decrease the prevalence of blindness in a relatively short period of time.

Blindness↗
PubMed1996

[The prospective study on the scope of extended operation for endometrial carcinoma].

OBJECTIVE: To investigate the scope of extended operation for endometrial carcinoma. METHODS: 105 patients underwent extended or less extended hysterectomy plus pelvic and/or para-aortic lymphadenectomy and 36 patients underwent less radical hysterectomy only. Prospective investigation of these 141 cases of endometrial carcinoma was undertaken. RESULTS: Of the 105 cases, lymph node metastasis (18.10%) occurred in 19 cases. Metastasis were found in all stages except stage Ia. The incidences of lymph node metastasis in stage Ib and stage Ic were 8.82% and 21.05% respectively. Of the 141 cases of extended or less extented hysteretomy, 2 were with parametrial connective tissue metastasis (stage II and stage III b), 2 with parametrial lymph node metastasis (stage I c and stage III b) and 2 with parametrial vascular involvement (stage I b and stage I c). CONCLUSIONS: The extended or less extended hysterectomy and lymphadenectomy should be performed in all patients of endometrial carcinoma except those of stage I a.

Adenocarcinoma↗
PubMed1996

[The changes in firing rates of ventromedial hypothalamic neurons and its modulations by electroacupuncture, arcuate nucleus and locus coeruleus during the immune response].

30 adult SD rats were divided into 3 grous: normal control goup; SRBC immune group (on 5th day after SRBC injection) and MSG(MSG injection at newborn stage) + SRBC group. The changes of the spontaneous firing rates of ventromedial hypothalamus (VMH) neurons and evoked responses by electroacupuncture (EA) and locus coeruleus (LC) stimulation were recorded. The results were as follows: (1) The spontaneous firing rate of VMH neurons was significant increase in the SRBC group. The firing rate in the MSG + SRBC group was higher than that in the control group, and lower than that in the SRBC group. There were statistical differences between them. (2) EA can increase the firing rates in all groups. The effect of EA was the most significant in the SRBC group, and more significant in the MSG + SRBC group. (3) The firing type of most VMH neurons showed first excited then inhibited biphasic response following stimulation LC in the SRBC and the MSG + SRBC groups. EA showed some increase in effect of the excited modulation from LC to VMH in the SRBC group. The results suggest that VMH might be an important neuroendocrinal link in immunoresponse. EA can increase the immune function of SRBC on VMH. LC and beta-endorphine neurons of arcuate nucleus might participate in the EA mediated immunoresponse.

Animals↗
PubMed1996

[The effects of C-fibers of primary afferent on immune responses regulated by EA in mice].

This work showed that electroacupuncture (EA) could enhance the ability of multiple immune responses in vehicle-treated animals. To study the role of primary sensory afferent C-fibers in the effect of EA on immume response, the experiments were performed on adult mice treated by capsaicin (cap) (50mg/kg) in neonate, cap is a tool drug selectively impairing afferent C-fibers. We found that the basal levels of multiple immune responses were changed apparently, showing that except the serum IgG decreased, all the spleen weight, thymus weight, spleen PFC, LTT, IL-2 and hemoagglutinating antibody titer elevated obviously in cap-treated mice as compared to that in vehicle control group. After the cap-treated mice were given EA, the levels of immune responses were found to be identical with cap-treated control group. The effects of EA-regulated immune response in vehicle-treated mice could not be observed in the cap-treated mice. The results mentioned above indicated that the effects of EA-regulated immune response were related to cap-sensitive afferent C-fibers.

Afferent Pathways↗