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Biomedical subjects

S Tang

Publications and source records attributed to S Tang.

At least 145 records · Page 8Linked to original sources
PubMed1998

The tomato Cf-9 disease resistance gene functions in tobacco and potato to confer responsiveness to the fungal avirulence gene product avr 9

The Cf-9 gene encodes an extracytoplasmic leucine-rich repeat protein that confers resistance in tomato to races of the fungus Cladosporium fulvum that express the corresponding avirulence gene Avr 9. We investigated whether the genomic Cf-9 gene functions in potato and tobacco. Transgenic tobacco and potato plants carrying Cf-9 exhibit a rapid hypersensitive cell death response (HR) to Avr 9 peptide injection. Cf 9 tobacco plants were reciprocally crossed to Avr 9-producing tobacco. A developmentally regulated seedling lethal phenotype occurred in F1 progeny when Cf9 was used as the male parent and Avr 9 as the female parent. However, when Cf9 was inherited in the maternal tissue and a heterozygous Avr 9 plant was used as the pollen donor, a much earlier reaction was caused, leading to no germination of any F1 seed. Detailed analysis of the Avr 9-induced responses in Cf 9 tobacco leaves revealed that (1) most mesophyll cells died within 3 hr (compared with 12 to 16 hr in tomato); (2) the macroscopic HR was visible at an Avr 9 titer five times lower than that which caused visible symptoms in tomato; (3) the HR invariably extended into noninjected panels of the tobacco leaf; (4) no HR occurred in leaves of young tobacco plants; (5) in older plants, the HR was dramatically enhanced by sequential Avr 9 challenges; and (6) coexpression of a salicylate hydroxylase transgene (nahG) from Pseudomonas putida reduced the severity of the macroscopic leaf HR and also restored germination to Cf 9 x 35S:Avr 9 F1 seedlings. Simultaneous introduction of Cf-9 homologs (Hcr 9-9 genes A and B or D) along with the native Cf-9 gene did not alter the responses that were specifically induced by Avr 9. Various ways to use the Cf-9-Avr 9 gene combination to engineer broad-spectrum disease resistance in several solanaceous species are discussed.

Journal Article↗
PubMed1998

Integrated analyzer and classifier of glottographic signals.

Electroglottography (EGG) and photoglottography (PGG) are two plausible methods to study voice production for monitoring the patterns of laryngeal vibrations. It has been suggested that measures such as open quotient and speed quotient calculated from glottographic signals can provide useful information regarding pathological phonation. In this paper, an integrated analyzer and classifier of glottographic signals was implemented. The system makes it possible to calculate the measures from digitized EGG and PGG signals automatically in order to examine vocal fold abnormality. The system developed several techniques to extract features from glottographic signals and proposed a statistical classification method that can possibly aid the diagnosis process. To check the reliability of the system, a training set and a test set of glottographic signals from normal people and patients with recurrent/superior laryngeal paralysis were analyzed and classified by the system. The results showed that the system is a useful tool for quantitative study of phonatory pathophysiology and can be used by the examiner who is interested in the clinical examination of glottographic signals. Moreover, glottographic techniques may have some clinical applications in the quantitative documentation of phonatory function in patients with voice disorders but requires further evaluation before clinical application.

Electrodiagnosis↗
PubMed1998

Molecular, genetic and physiological analysis of Cladosporium resistance gene function in tomato.

Characterization of the DNA sequence of 4 tomato leaf mould disease resistance genes (Cf-2, Cf-4, Cf-5 and Cf-9) leads to the prediction that they encode C-terminally membrane anchored glycopeptides with many extracytoplasmic leucine rich repeats (LRRs). The N terminal LRRs are variable between the Cf-genes, suggesting a role in specificity, and the C terminal LRRs are more conserved, suggesting a role in signal transduction. Genetic analysis has revealed several Rcr genes that are required for Cf-gene function; their isolation will help us understand how Cf-genes work. Cf-9 confers responsiveness to pathogen-encoded Avr9 peptide on introduction to tobacco. Tobacco suspension cultures carrying the Cf-9 gene produce reactive oxygen species in response to Avr9 peptide, whereas untransformed cultures do not. The significance of these observations is discussed.

Cladosporium↗
PubMed1998

[Study on method of sampling and analysis of trichloroaniline in the air].

Trichloroaniline in the air was collected with 50% ethanol and separated with a column OV-17:OV-210 ECD as a detector. The best conditions of sampling and determining were selected through the orthogonal experimental design. The detectable limit was 0.01 mg/L. When the concentration of trichloroaniline in the air was 0.5-10 mg/L, the relative standard deviation (RSD) was 4.3%-3.7%. There was a linear relation within the range of 0.02-40 mg/L. The sampling efficiency was 99.1%-100%. The samples were stable for at least 15 days. It is proved that this method is accurate, fast, simple and sensitive. It is suitable for the determination of trichloroaniline in the air.

Air Pollutants↗
PubMed1998

[HA-coated titanium implants used as orthodontic anchorage. An experimental investigation of implant stability and peri-implant neck tissue in dogs].

This study was aimed at the feasibility of using HA-coated titanium endosseous implants as orthodontic anchorage. These implants installed in dog's mandibles were loaded with the orthodontic force of 150 g for 3 months. The stability of the implant and the peri-implant neck tissue were investigated with radiograph and index evaluation. The findings demonstrated that no implant was mobile or loose or dislocated. The soft tissue around the cervical part of the implants had a slight inflammation because of bad oral hygiene and the stimulation of residual food attached to the stainless string. However, no resorption of marginal alveolor bone was found under sustained orthodontic force. The above results suggest that the HA-coated titianium implant can be used as anchorage for short-term orthodontic treatment.

Animals↗
PubMed1998

[Detection of Mycobacterium tuberculosis DNA in peripheral blood mononuclear cells from patients with pulmonary tuberculosis by polymerase chain reaction technique].

OBJECTIVE: To evaluate the clinical value of detection of Mycobacterium tuberculosis DNA (MTB-DNA) in peripheral blood mononuclear cells (PBMC) for diagnosis of pulmonary tuberculosis. METHOD: Polymerase chain reaction (PCR) technique was used to amplify gene of 240 bp DNA fragment prepared by Triton X-100 method, and some factors affecting PCR result were also analysed. RESULT: In blood samples of 89 patients with pulmonary tuberculosis and in sputum samples of 84 patients with pulmonary tuberculosis, the positive rates of PCR were 73% and 57% respectively, and the total positive rate of combinative detection of blood and sputum samples was 87% in 84 pulmonary tuberculosis patients. In 30 non-tuberculosis patients, 3 showed MTB-DNA positive. CONCLUSION: PCR technique prepared by Triton X-100 method is rapid, simple, specific, and sensitive for detection of MTB-DNA in PBMC, and its sensitivity and accuracy could be increased in combination with sputum MTB examination. Detection of MTB-DNA in PMBC is of value in diagnosis of pulmonary tuberculosis.

DNA, Bacterial↗
PubMed1998

Percutaneous transluminal angioplasty for stenosis of arteriovenous fistulae: a review of local experience.

The stenosis and subsequent thrombosis of the arteriovenous fistulae may lead to a loss of vascular access sites; this a major problem in chronic haemodialysis patients. Percutaneous transluminal angioplasty has been a popular way of correcting such lesions in recent years. We have reviewed patients who underwent this operation from 1993 to 1996 at the Queen Mary Hospital. Among 11 patients who were documented as having arteriovenous fistula stenosis, 60% of lesions were in the anastomotic area while 40% were in the venous limb. All patients had abnormal dialysis blood line pressures corresponding to the actual site of stenosis. The initial success rate of percutaneous transluminal angioplasty in treating the stenotic lesions was 73%. This method is thus a promising form of semi-invasive treatment for symptomatic arteriovenous fistula stenosis.

Journal Article↗
PubMed1998

[Temporary keratoprosthesis for surgery of severe injuries of ocular anterior and posterior segments].

OBJECTIVE: To evaluate the treatment of severe ocular injuries of anterior and posterior segments with temporary keratoprosthesis used in combined operations. METHODS: With temporary keratoprosthesis a combined operation including pars plana vitrectomy, air-fluid exchange, silicone oil fill in, use of perfluorocarbon liquid, foreign body removal and partial penetrating keratoplasty was performed on 18 eyes of 18 patients with severe ocular injuries, and the postoperative changes and recovery were observed. RESULTS: All eyes were rescued, the visual acuity was increased in 12 eyes, above 0.1 being in 5 eyes, retinal detachment recurred in 3 of 10 eyes, vitreous opacity was present in 1 eye, secondary glaucoma in 1 eye, and atrophy in 1 eye as its preoperative status. CONCLUSION: Temporary keratoprosthesis used in the combined surgeries of anterior and posterior ocular segments is an effective method for treatment of severe ocular injuries.

Adolescent↗
PubMed1998

[Stability of HA-coated titanium implants used as orthodontic anchorage].

12 two-stage HA-coated titanium implants were inserted into the mandibular alveolar bones of two dogs were loaded with orthodontic force of 150 gram for 3 months. The stability of the implants under orthodontic force were studied with intraoral and radiographic examinations. The results showed that both intraoral and radiographic analysis were reliable for assessing implant stability, and no signs of fixture dislocation were found during the force application period (P > 0.05), while the abutment was tilted after being loaded for 2 to 3 months. This suggests that HA-coated titanium implants remain stable enough under orthodontic force and are suitable as anchorage for short-term orthodontic therapy after design of the implant neck is improved.

Animals↗
PubMed1998

[Preliminary study on HA-coated titanium implants used as anchorage for protraction of dog molar teeth].

HA-coated titanium implants were placed surgically into dog mandible to protract the mandibular second molars with an orthodontic force of 150 g. During the force application period of 3 months, the movement of the molars was tested periodically and relevant reasons of movement were analysed. The results showed that the mesial moving distances of the second molar were respectively 1.04 mm, 1.68 mm and 1.76 mm at the first, second and third month, and the main reason of tooth mobility was ascribed to the implant anchorage. It can be concluded tiat HA-coated titanium implant can be used as anchorage for moving and fixing posterior teeth in the orthodontic treatment.

Animals↗
PubMed1998

[Assessment of marginal tissue around HA-coated titanium implants for orthodontic anchorage in dogs].

12 two-stage HA-coated titanium implants placed in dogs' mandibles were loaded with an orthodontic force of 150 g for 3 month. Gingival bleeding index, plague and calcucus index, mobility index, probing depth and marginal bone were investigated. The results showed that the implants were stable and peri-implant soft tissue displayed slight inflammation, but no marginal bone absorption and no difference of bone quantity between the tension side and compression side were found. It can be concluded that the clinical trials of marginal tissue around the HA-coated titanium implants are satisfactory when the implants are used as anchorage for short-term orthodontic treatment.

Animals↗
PubMed1998

[Management of very complicated retinal detachment].

PURPOSE: To evaluate the management for a group of complicated retinal detachment in very severe conditions including(A) rhegmatogenous retinal detachment associated with severe posterior and anterior PVR, (B) giant retinal tear (GRT) retinal detachment with severe PVR, (C) severe perforating eye injury with tractional retinal detachment. METHODS: A total number of 31 eyes from 31 patients was included, in which 14 eyes were in group A, 8 eyes were group B and 9 eyes group C. Procedures including scleral buckling, encircling, cryotherapy, total vitrectomy, epiretinal membrane peeling/excision, relaxing retinectomy, use of perfluorocarbon liquid and silicone oil were applied to all patients. Patients were followed up for three to 16 months. RESULTS: Retinas of 21 out of 31 eyes(67.7%) were completely reattached and 5 eyes (16.1%) were partially reattached, 5 eyes were failed(16.1%). Postoperative vision was significantly improved in 25 eyes. The visual acuity of 19 eyes was better than 0.02, while before operation only two eyes were better than 0.02. PVR and GRT patients had better results. CONCLUSION: The results showed that a big part of very complicated retinal detachment which was called as hopeless cases could still be successfully treated with comprehensive procedures, more than half of them may have useful vision which may obviously improve their life quality.

Adolescent↗
PubMed1998

The immunological studies on proliferative intraocular disorders: investigation of activated lymphocytes, macrophages and HLA-DR.

PURPOSE: To investigate whether activated B lymphocytes (CD23), activated T lymphocytes (CD25), macrophages (CD68) and human leucocyte antigen class II antigen (HLA-DR) were existed in epiretinal membranes (ERMs) and subretinal membranes (SRMs) of proliferative intraocular disorders (PID). METHODS: Twenty specimens of ERMs from rhegmatogenous retinal detachment with proliferative vitreoretinopathy (PVR), traumatic PVR and secondary traction retinal detachment, and two specimens of SRMs from rhegmatogenous retinal detachment with PVR and traumatic PRV were studied using immunohistochemical staining. RESULTS: CD68 and HLA-DR were found in all specimens, CD23 and CD25 in 4 cases of ERMs and in 1 case of SRMs, respectively. CONCLUSIONS: 1. The ERMs and SRMs of different etiology shared a common basis of inflammation and immunopathology. 2. There would be secondary cellular and humoral immunity in the ERMs and the SRMs of PID.

Antigens, CD↗
PubMed1997

Requirement for protein kinase C theta for cell cycle progression and formation of actin stress fibers and filopodia in vascular endothelial cells.

Activation of the protein kinase C (PKC) family with phorbol esters induces endothelial proliferation and angiogenesis, but which of the events that constitute angiogenesis are affected by individual members of the PKC family is unknown. In rat capillary endothelial (RCE) cells, serum stimulation increased expression of a single PKC isoenzyme, PKCtheta, and its translocation to the periphery. Conditional overexpression of a dominant-negative mutant of PKCtheta markedly inhibited RCE proliferation, as well as closure of a "wound" by RCE migration and formation of capillary rings and tubules in vitro. PKCtheta inhibition delayed the endothelial cell cycle at the G2/M phase and prevented formation of actin stress fibers and filopodia but not lamellipodia. The defect in cell morphology and wound closure in PKCtheta-kn cells was reversed by overexpressing kinase-active PKCtheta, indicating that these RCE functions depend upon PKCtheta substrates. Thus, PKCtheta is required for multiple processes essential for angiogenesis and wound repair, including endothelial mitosis, maintenance of a normal actin cytoskeleton, and formation of an enclosed tube.

Actins↗
PubMed1997

Myelin-associated glycoprotein interacts with neurons via a sialic acid binding site at ARG118 and a distinct neurite inhibition site.

Inhibitory components in myelin are largely responsible for the lack of regeneration in the mammalian CNS. Myelin-associated glycoprotein (MAG), a sialic acid binding protein and a component of myelin, is a potent inhibitor of neurite outgrowth from a variety of neurons both in vitro and in vivo. Here, we show that MAG's sialic acid binding site is distinct from its neurite inhibitory activity. Alone, sialic acid-dependent binding of MAG to neurons is insufficient to effect inhibition of axonal growth. Thus, while soluble MAG-Fc (MAG extracellular domain fused to Fc), a truncated form of MAG-Fc missing Ig-domains 4 and 5, MAG(d1-3)-Fc, and another sialic acid binding protein, sialoadhesin, each bind to neurons in a sialic acid- dependent manner, only full-length MAG-Fc inhibits neurite outgrowth. These results suggest that a second site must exist on MAG which elicits this response. Consistent with this model, mutation of arginine 118 (R118) in MAG to either alanine or aspartate abolishes its sialic acid-dependent binding. However, when expressed at the surface of either CHO or Schwann cells, R118-mutated MAG retains the ability to inhibit axonal outgrowth. Hence, MAG has two recognition sites for neurons, the sialic acid binding site at R118 and a distinct inhibition site which is absent from the first three Ig domains.

Amino Acid Sequence↗
PubMed1997

Soluble myelin-associated glycoprotein (MAG) found in vivo inhibits axonal regeneration.

Myelin-associated glycoprotein (MAG) is a potent inhibitor of axonal regeneration when used as a substrate for growth. However, to be characterized definitively as inhibitory rather than nonpermissive, MAG must also inhibit axonal regeneration when presented in solution. Here, we show that soluble dMAG (extracellular domain only), released in abundance from myelin and found in vivo and chimeric MAG-Fc, can potently inhibit axonal regeneration. For both dMAG and MAG-Fc, inhibition is dose-dependent. If myelin-conditioned medium is immunodepleted of dMAG, or if a MAG antibody is included with MAG-Fc, inhibition is completely neutralized. Together with MAG's ability to induce growth cone collapse, these results demonstrate that MAG is an inhibitory molecule and not merely nonpermissive. The results also suggest that MAG binds to a specific receptor and initiates a signal transduction cascade to effect inhibition. Importantly, these results indicate that soluble dMAG detected in vivo could contribute to the lack of regeneration in the mammalian CNS after injury.

Animals↗