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Biomedical subjects

S Zhang

Publications and source records attributed to S Zhang.

At least 667 records · Page 37Linked to original sources
PubMed1998

Pirfenidone reduces fibronectin synthesis by cultured human retinal pigment epithelial cells.

PURPOSE: Pirfenidone is a novel anti-fibrotic drug that has been shown to inhibit fibroblast growth and collagen synthesis induced by transforming growth factor (TGF)-beta1. In the present study we investigated the ability of pirfenidone to moderate fibronectin synthesis by cultured human retinal pigment epithelial (RPE) cells maintained in media containing 1% foetal bovine serum when stimulated with TGF-beta1. METHODS: Primary human RPE cultures were used. Treatments included TGF-beta1, pirfenidone and pirfenidone with TGF-beta1. After 72 h treatments, cell growth was determined by cell counting and fibronectin was measured by ELISA. RESULTS: Transforming growth factor-beta1 (1-10 ng/mL) increased the production of soluble fibronectin, while pirfenidone (300 micromol/L) significantly reduced the TGF-beta1-induced synthesis of fibronectin. Pirfenidone alone had no effect on fibronectin synthesis by cultured RPE cells. CONCLUSION: We conclude that the anti-fibrotic effect of pirfenidone may be partly mediated through inhibition of TGF-beta1-induced fibronectin synthesis.

Antineoplastic Agents↗
PubMed1998

Roles of the catalytic domain and two cellulose binding domains of Thermomonospora fusca E4 in cellulose hydrolysis.

Thermomonospora fusca E4 is an unusual 90.4-kDa endocellulase comprised of a catalytic domain (CD), an internal family IIIc cellulose binding domain (CBD), a fibronectinlike domain, and a family II CBD. Constructs containing the CD alone (E4-51), the CD plus the family IIIc CBD (E4-68), and the CD plus the fibronectinlike domain plus the family II CBD (E4-74) were made by using recombinant DNA techniques. The activities of each purified protein on bacterial microcrystalline cellulose (BMCC), filter paper, swollen cellulose, and carboxymethyl cellulose were measured. Only the whole enzyme, E4-90, could reach the target digestion of 4.5% on filter paper. Removal of the internal family IIIc CBD (E4-51 and E4-74) decreased activity markedly on every substrate. E4-74 did bind to BMCC but had almost no hydrolytic activity, while E4-68 retained 32% of the activity on BMCC even though it did not bind. A low-activity mutant of one of the catalytic bases, E4-68 (Asp55Cys), did bind to BMCC, although E4-51 (Asp55Cys) did not. The ratios of soluble to insoluble reducing sugar produced after filter paper hydrolysis by E4-90, E4-68, E4-74, and E4-51 were 6.9, 3.5, 1.3, and 0.6, respectively, indicating that the family IIIc CBD is important for E4 processivity.

Amino Acid Sequence↗
PubMed1998

Mechanical properties of a self-assembling oligopeptide matrix.

We have begun studies of a novel type of biomaterial derived from a recently-discovered class of ionic self-complementary oligopeptides. These short peptides (typically 8, 16, 24, or 32 amino acid residues with internally-repeating sequences) self-assemble in aqueous salt solution into three-dimensional matrices capable of favorable interactions with cells, and offer promise for useful bioengineering design based on rational changes in sequence. In this paper we present preliminary results on mechanical properties, combining experimental and theoretical approaches, of one particular example of these peptide materials, EFK8. The static elastic modulus was measured using an apparatus designed to allow sample fabrication and mechanical testing in the same system with the sample in aqueous solution. The material microstructure was examined by SEM and the measurements interpreted with the aid of a model for cellular solids. Values for the elastic modulus increased from 1.59 +/- 0.06 to 14.7 +/- 1.0 kPa for peptide concentrations increasing from 2.7 to 10 mg ml-1. SEM photographs showed the microstructure to consist of a relatively homogeneous lattice with fiber thickness of 10-30 nm independent of peptide concentration, but with fiber density increasing with peptide concentration. This behavior is consistent with scaling predictions from the cellular solids model and yields an estimate for the individual fiber elastic modulus in the range of 1-20 MPa. We therefore have provided some initial physical principles for guiding improvement of the mechanical properties of these new materials.

Biomechanical Phenomena↗
PubMed1998

slimb coordinates wg and dpp expression in the dorsal-ventral and anterior-posterior axes during limb development.

In the Drosophila leg disc, wingless (wg) and decapentaplegic (dpp) are expressed in a ventral-anterior and dorsal-anterior stripe of cells, respectively. This pattern of expression is essential for proper limb development. While the Hedgehog (Hh) pathway regulates dpp and wg expression in the anterior-posterior (A/P) axis, mechanisms specifying their expression in the dorsal-ventral (D/V) axis are not well understood. We present evidence that slimb mutant clones in the disc deregulate wg and dpp expression in the D/V axis. This suggests for the first time that their expression in the D/V axis is actively regulated during imaginal disc development. Furthermore, slimb is unique in that it also deregulates wg and dpp in the A/P axis. The misexpression phenotypes of slimb- clones indicate that the regulation of wg and dpp expression is coordinated in both axes, and that slimb plays an essential role in integrating A/P and D/V signals for proper patterning during development. Our genetic analysis further reveals that slimb intersects the A/P pathway upstream of smoothened (smo).

Amino Acid Sequence↗
PubMed1998

Changes in populations of Listeria monocytogenes inoculated on packaged fresh-cut vegetables.

A variety of wholesale and retail packaged vegetables and salads were inoculated with a mixture of strains of Listeria monocytogenes and incubated at 4 and 10 degrees C. Whole rutabagas, butternut squash, and onions, as well as packaged Caesar salad, carrots, coleslaw mix, and stir-fry vegetables were purchased from local supermarkets in the Ottawa area. L. monocytogenes population levels remained constant on all fresh-cut vegetables stored at 4 degrees C for 9 days, except for carrots and butternut squash: counts of cell numbers declined on carrots and increased on the butternut squash. Fresh-cut vegetables stored at 10 degrees C, however, supported good growth of L. monocytogenes on all vegetables tested, except for chopped carrots, where the population decreased approximately 2 log units over a 9-day storage period. As in the situation with the produce stored at 4 degrees C, butternut squash supported the highest rate of cell growth. In addition, Caesar salad and coleslaw mix were kept at 25 degrees C for 1 or 2 days before subsequent storage at 4 or 10 degrees C to stimulate extreme temperature-abuse conditions. In Caesar salad stored at 4 degrees C, by day 6 an initial 24- and 48-h temperature abuse at 25 degrees C led to a 1.21- and 2.55-log-unit population increase, respectively, over the control. Similar increases were observed on Caesar salads stored at 10 degrees C. Compared to Caesar salad, coleslaw mix temperature-abused at 25 degrees C and then stored at 4 degrees C supported slightly greater increases in the population of L. monocytogenes, i.e., a 3.22- and 3.83-log-unit increase over the control for the 1- and 2-day abused samples, respectively. Coleslaw mix samples temperature-abused and then stored at 10 degrees, however, only showed log unit increases of 1.75 and 1.94, respectively, compared to the controls. These results point to the importance of strict temperature control to prevent or reduce the growth of L. monocytogenes cells on fresh-cut vegetables.

Colony Count, Microbial↗
PubMed1998

Acute effects of carbofuran in workers of two pesticide plants.

This paper investigates the acute effects of carbofuran in workers of two pesticide-formulating plants. Mean airborne carbofuran concentrations ranged from 0.025 to 1.115 mg/m3 in plant A and from 0.018 to 0.067 mg/m3 in plant B, respectively. In workers of plant A the post-shift blood cholinesterase activity was significantly reduced, compared to pre-shift values. No difference in blood cholinesterase activity was found between pre- and post-shift values in workers of plant B. During the investigation, 25 cases of acute carbofuran poisoning were diagnosed by their clinical picture and depressed cholinesterase activity in blood. Usual symptoms included dizziness, weakness, blurred vision, nausea and sweating. Pallor, epigastric pain, vomiting and chest tightness occurred only in a few cases. Myosis was recorded in 24 cases. Fasciculation of muscle gastrocnemius induced by percussion was found in 6 cases, and four of them had also fasciculation of muscle orbicularis oculi. Inhibition of cholinesterase activity in the blood was related with the clinical features; however, the inhibition was rapidly reversible. In most cases, recovery was complete within 2-3 hours, with or without atropine treatment, after the subjects were removed from exposure. Rapid onset, mild illness and quick recovery are typical characteristics of occupational acute carbofuran poisoning.

Acute Disease↗
PubMed1998

[Study on health status of 3,333 old people in Chengdu City, Sichuan Province].

In order to study the health status of 3,333 old people (over 60) in Chengdu city, a survey was carried out from May 1996 to Nov. 1996. Results revealed that 79.4% of old people had a history of chronic diseases. The first ten common chronic diseases were stated as follows: rheumatic arthritis, hypertension, benign prostatic hypertrophy, chronic bronchitis, cataract, chronic gastritis, osteoarthrosis, asthma and diabetes mellitus. There were significant differences of body weight index, vision and auditus disorder among old people according to their age (P < 0.01). As ageing grows, old people's physical condition and daily-life-capacity decline. In order to improve the quality of life among the aged, following aspects as popularizing health education on self care, strengthening programs on prevention and care of chronic diseases, expanding the medical and nursing services in community and easier access to hospitalization etc should be promoted.

Aged↗
PubMed1998

[Analysis on the data regarding brucellosis at the National Monitoring Center].

Surveillance on brucellosis was carried out in 15 major monitoring places in 14 provinces from 1990 to 1996. The result indicated that in a few monitoring places the epidemic situation was stable but in many monitoring places outbreak had occurred in one or two monitoring places. Major source of infection was from infected sheep and cattle while in some old epidemic areas the pastoral area was active, which kept animals continuously excrete bacteria, making the potential of outbreak brucellosis exist. A tendency showed that the epidemic area was shifting to the farming and stockbreeding and agricultural areas. A comprehensive strategy including effective management and control the circulation of causative agent, needs to be developed.

Adolescent↗
PubMed1998

Preventive effect of artemether on schistosome infection.

OBJECTIVE: To study the preventive effect of artemether (Art) in protecting the people from schistosome infection during flood fighting in schistosomiasis endemic area of Poyang Lake, Jiangxi Province. METHODS: From mid July to mid August in 1996, the water level in Poyang Lake rose due to torrential rains and 2 embankments, Zhedi and Jiangtongdi, which appeared in dangerous situation and were selected as the pilot spots. After those who went to fight against flood arrived at the pilots their sera were collected within 48 hours and were examined with indirect hemagglutination test (IHA), enzyme-linked immunosorbent assay (ELISA) and McAb-ELISA. Individuals with negative outcome in the 3 tests were then selected as the study subjects and were allocated randomly to the Art or the control group. The first dose of Art given to the individuals contacted with the infested water within 11-15 days was 6 mg/kg. If the individual continually contacted the infested water, the same dose of Art was given once every 15 days. After the individuals withdrew from the pilot, one more dose of Art was administered 7-15 days later. Placebo (starch) was given to individuals in the control group at the same period as in artemether group. Stool examinations were made in both groups 40-50 days after the last medication for evaluation of the preventive effect of artemether. Double blind method was used in the administration of both artemether and placebo. RESULTS: In Zhedi pilot, the individuals fought against flood for about 1 month. In Art group, 99 individuals receiving 3 doses of the drug completed the stool examination with egg-positive rate of 4% and no acute schistosomiasis was seen. In the control group, among 110 people who completed the observation, 44 were egg-positive with an infection rate of 40%, and 29 were identified as having acute schistosomiasis. In Jiangtondi, the studied individuals contacted the infested water for only about 4 hours. But in the control group 4 out of 102 individuals were egg-positive, while none of the 103 individuals in Art group receiving 2 doses of the drug showed schistosome infection. No apparent side effect was seen in the people treated with artemether. CONCLUSION: After oral Art was given to the people fighting against flood in schistosomiasis endemic area of Poyang Lake, it was shown that the oral Art has a promising effect on controlling acute schistosomiasis and reducing the infection rate.

Adolescent↗
PubMed1998

[Restoration of supination of forearm by flexor carpi radialis transfer].

The dysfunction of supination of forearm following injury of brachial plexus or poliomyelitis always affects the function of hand. To find the dynamic muscle for restoration of the supination, the flexor carpi radialis was investigated on fifty male cadavers. The blood supply of the muscle was polygenic, mainly derived from the humoral and radial arteries. The movement of the muscle was innervated by median nerve. If the proximal 1/3 belly of the muscle was reserved, the blood supply and innervation of the complete muscle was reserved. According to the anatomic data, the operative procedure was designed as following: transfer the distal 2/3 of flexor carpi radialis over the ulnar aspect of the forearm to the dorsal-radial side, the tendon was fixed on the radius shaft 6 to 10 cm proximal to the styloid process with forearm in full supination. Four patients were treated and after followed up for 3.2 years average, the supination restored. It was discussed that in case of paralysis of the flexor carpi ulnaris and pronator teres, the optimal choice to restore the supination would be flexor carpi radialis.

Adult↗
PubMed1998

[Surgical therapy of hallux valgus in the young and middle-aged female].

OBJECTIVE: To correct hallux valgus in the young or middle-aged female. METHOD: Through dissecting foot specimens with hallux valgus we found that the intrinsic factor that caused hallux valgus was a "capstan" like mechanism of pressure. In order to eliminate the mechanism of the deformity, we cut off the link between the adductoris hallucis and the hallux completely. The tendon of adductoris hallucis was sutured to the fascial flap of hallucis bursa passing through a hole in the caput of the metatarsus. By this way the adductoris hallucis was fixed to the 1st metatarsus strongly, thus it pulled the 1st metatarsus directly. RESULTS: Twenty feet received this operation. 18 feet were followed up for 0.5-4 years. The rate of excellent and good results was 100%. CONCLUSION: This operation by suturing the adductoris hallucis with the fascial flap of the hallucis bursa not only can relieve pain but also restore the normal appearance of the foot.

Adult↗
PubMed1998

An experimental study on rhBMP-2 composite bone substitute for repairing craniomaxillary bone defects.

OBJECTIVE: To measure bone regenerative effects in animal calvarial or mandibular critical-size defects using recombinant human bone morphogenetic protein-2 (rhBMP-2) combined with four selected carriers. MATERIALS AND METHODS: The composite bone grafts were obtained by combining rhBMP-2 with chitin, coral, coral-based porous HA (CHA), and xenogeneic cancellous bone, respectively. These materials were implanted on the calvarial or mandibular defect of rabbits and on the calvarial defect of rats. Each carrier material was also studied as a control group. The animals were examined 2, 4, 8, and 12 weeks after implantation by radiography, histology (under light microscope and scanning electron microscope), immunohistochemistry, and biomechanics. RESULTS: The results showed that the composite graft was absorbed gradually after it was implanted into the defect, during which time new bone was formed within the combined material in the defect site; the amount of new bone increased as time elapsed. At 12 weeks the composite was replaced completely by bone except in the CHA group. In contrast, a large amount of fibrous tissue, and little new bone, formed on the area of the bone defect when the carrier material alone was implanted. CONCLUSIONS: All materials tested seem to be suitable carriers for rhBMP-2, which plays a very important role in new bone formation. These composite bone substitutes may be ideal materials for repairing various bone defects in the craniomaxillofacial region.

Animals↗
PubMed1998

[Anatomic study of the musculus depressor septi nasi in unilateral cleft lip nasal deformity].

OBJECTIVE: This study was to investigate the nasal musculature and its relationship with the deformities of the unilateral cleft lip nose. METHOD: The anatomic and histological examination and comparison of the musculus depressor septi nasi (MDSN) were performed in 33 normal cadavers and 30 patients with unilateral cleft lip undergoing the operation for secondary nasal deformities. RESULT: It was found that the MDSN in the cleft side of a unilateral cleft lip nose is lacking. CONCLUSION: Because of the anatomic deficiency on the cleft side, the function of the normal side is pathologically increased. The functional imbalance between the normal and abnormal side may bring about dislocation and malformation of the base of nasal columella as well as the septal structures.

Abnormalities, Multiple↗
PubMed1998

[Alteration of peritoneal lymphocyte transformation and its interleukin-2 release in patients with infertility and endometriosis].

OBJECTIVE: To study the relationship between alteration of peritoneal lymphocyte transformation activity, its interleukin-2 (IL-2) release and infertility associated with endometriosis. METHODS: Peritoneal fluid was collected from 15 infertile patients with endometriosis (endometriosis group) and 13 normal fertile women (control group). Lymphocyte transformation activity were determined in peritoneal fluid by morphometry. IL-2 contents were determined in peritoneal fluid and supernatants of cultured pelvic lymphocytes by biological method. RESULTS: Lymphocyte transformation activity reinforced (P < 0.001) and IL-2 contents increased in peritoneal fluid and supernatant of cultured pelvic lymphocyte in the endometriosis group than those in the control group (P < 0.01, P < 0.001 respectively). There is significant positive correlation between lymphocyte transformation rate and IL-2 activity of cultured supernatant in endometriosis group (P < 0.001). CONCLUSION: The increase of IL-2 content in the samples of endometriosis may play an important role in infertility with endometriosis.

Adult↗
PubMed1998

[Clinical study on the orthodontic treatment of deep overbite with bite plane].

Fifteen cases of patients with incisal Angel's Class II obserbite were orthodontically treated with bite plane and analysed with cephalometric radiograph. The results showed that bite plane can correct deep overbite rapidly (within 6 months) and effectively. The mechanism of bite plane was to raise the posterior teeth (1.1 mm) and to lower the anterior teeth (0.8 mm).

Adolescent↗