Biomedical subjects

S Li

Publications and source records attributed to S Li.

At least 505 records · Page 28Linked to original sources

PubMed2000

Ambient hypoxia reverses retinal vascular attenuation in a transgenic mouse model of autosomal dominant retinitis pigmentosa.

PURPOSE: Loss of retinal capillaries is an inherent component of late stage autosomal dominant retinitis pigmentosa (ADRP). This study examined the hypothetical role of tissue hyperoxia in this vascular attenuation process and tested the potential of ambient hypoxia to reverse it. METHODS: Transgenic mice expressing a mutant opsin gene with a 3-bp deletion of isoleucine at codon 255/256 were used. This model is characterized by early onset of a rapidly progressing retinal degeneration that by postnatal day (P)20 results in the loss of all but one row of photoreceptor nuclei. At P20 some mice were placed in 12% oxygen until they were euthanatized at P26. The remainder were maintained in normoxia and killed at the same age. Retinas were dissected, stained for ADPase, and flat-mounted. RESULTS: Deep plexus capillary density was significantly different in normoxic normals versus transgenics at 20 days of age (P: </= 0. 005). An additional 65% reduction of capillary density occurred within the deep plexus of normoxic transgenics between P20 and P26 (P: </= 0.005). Ambient hypoxia between days P20 and P26 reversed this trend, causing an increase in deep capillary plexus density of nearly 100% (P: </= 0.001). CONCLUSIONS: This model of ADRP demonstrates two important features of human retinitis pigmentosa: photoreceptor cell death and subsequent retinal capillary atrophy. Low ambient oxygen was used to reverse the capillary atrophy and to stimulate new capillary growth, implying that retinal oxygen tension may link these two features of the pathology. The implications of this study hold importance for strategies designed to treat retinitis pigmentosa with retinal cell transplantation.

Animals↗

PubMed2000

Morphology and formation mechanism of hydroxyapatite coating by hydrothermal method on CaO-SiO2-B2O3-Na2O glass.

Hydrothermal method was used to prepare the hydroxyapatite (HA) coating on CaO-SiO2-B2O3-Na2O glass. The phase composition, morphology and microstructure of HA coated glass composites were analyzed using XRD, EPMA, FT-IR and SEM techniques. It revealed that HA coating possessed a porous gradient construction; HA coating was tightly bonded with the glass substrate by the interface layer. During the formation of HA coating, the hydrated silica produced by the corrosion of glass substrate in the hydrothermal solution provided favorable sites for apatite nucleation. With the dissolving of HA powder and the growth of apatite small crystallites, Ca+, PO(4 (3-)) ions would precipitate on the surface of glass to form the HA coating. Silicon element released from glass reacted with calcium produced by the dissolution of HA to form the tight reaction layer. HA coating is formed by the mechanism of dissolving-ions immigrating-precipitating pattern.

Calcium↗

PubMed2000

Dissolution behavior of hydroxyapatite coating by hydrothermal method: an in vitro study.

Hydroxyapatite (HA) coated CaO-SiO2-B2O3-Na2O glass composites prepared by a hydrothermal coating method were soaked in four kinds of solutions to evaluate the dissolution behavior and the chemical stability. 0.5 mol/l HCl and 0.5 mol/l HNO3 were used as acidic solution, and 5% physiological saline and sodium lactate compound solution as the neutral physiological solution. It was found that HA coated glass composites had the better chemical stability and the corroding-resistance ability. The dissolution behavior of the HA coating was mainly correlated with the phase composition of the as-received HA coating and its microstructure as well as the pH value of the solution.

Calcium↗

PubMed2000

Eosinophilic ulcer of the oral mucosa: a clinicopathological analysis.

OBJECTIVE: To explore the clinical characteristics, histologic features, method of treatment, and possible etiology of eosinophilic ulcer of the oral mucosa. METHOD: Eight cases of eosinophilic ulcer of the oral mucosa were analyzed. RESULTS: In all cases, the ulcer site was the tongue. Ulcers were unifocal, had a benign course, and three of patients had a history of EUOM recurrence. Pathological features showed an extensive inflammatory cell infiltration, with predominantly eosinophilic cells throughout the submucosa. All ulcers were treated with either conservative excision or incisional biopsy. CONCLUSIONS: Eosinophilic ulcer is a rare, self-limiting benign disease that often appears in older adults or children. Its etiology remains obscure and may be associated with traumatic factors. This study provides useful information on clinical and pathological features, diagnosis, treatment, and prognosis, as well as the possible etiology of this disease.

Adolescent↗

PubMed2000

Preparation of monoclonal antibody against human m3 receptor.

AIM: To raise monoclonal antibody against human m3 receptor. METHODS: The m3 receptor selective peptide segments deduced from its gene were chemically synthesized, coupled to keyhole limpet hemocyanin carrier protein, and injected to Balb/c mice to raise monoclonal antibody. Antibody was purified by a combination of two-step precipitation methods and ion-exchange chromatography. The specificity of monoclonal antibody was tested by enzyme-linked immunosorbent assay, immunohistochemistry, and radioligand binding assay of receptors. RESULTS: The monoclonal antibody specifically bound to the protein of rat salivary gland and m3 peptide, but not m4 peptide. In radioligand binding assay of receptors, monoclonal antibody inhibited the binding of 3H-QNB to muscarinic receptor in rat salivary gland, but not in rat heart, and could not inhibit the binding of 3H-PZ to rat brain cerebral cortex membrane protein. Immunohistochemical study showed that the human salivary cell surface was strongly stained, whereas the human heart cell surface was not. CONCLUSION: Highly purified (96.3%) monoclonal antibody against the m3 receptor peptide recognized the m3 receptor.

Animals↗

PubMed2000

[Anatomical study and clinical applications of the tensor fascia lata myocutaneous flap].

OBJECTIVE: To explore the causes of blood circulation problems in 3 of 6 cases of pedicled tensor fascia lata myocutaneous flap transferring. METHODS: Anatomical study was performed on 16 cadavers (32 sides) after red emulsion injection. RESULTS: On 22 sides of 12 cadavers, the nutrient arteries lie in the muscle; on 2 sides of 2 cadavers, intramuscular nutrient arteries coexist with the big branches anterior to the muscle; on 4 sides of 3 cadavers, intramuscular nutrient arteries coexist with the big branches in the loose connective tissue deep to the muscle; on 4 sides of 3 cadavers, the nutrient arteries locate in the subcutaneous layer. According to the anatomical observations, much attention were paid to protect the vessels deep, superficial and anterior to the muscle during surgery, which resulted in successful clinical applications in 8 cases. CONCLUSIONS: The supplying arteries of the tensor fascia lata myocutaneous flap may exit not only intramuscularly, but also deep, superficial and anterior to the muscle. Special attention should be paid to them during operation.

Adolescent↗

PubMed2000

[Experimental study of lymph node flap transplantation for treatment of lymphedema].

OBJECTIVE: We investigated the treatment of lymphedema by using lymph node flap. METHODS: Upper limbs' lymphedema model in 14 rabbits were divided into two groups. They were treated with lymph node flap transplantation and general flap transplantation. RESULTS: Lymph node transplantation can reduce lymphedema and general flap transplantation can not significantly reduce lymphedema. CONCLUSION: Lymph node flap can be used to treat extremity's lymphedema.

Animals↗

PubMed2000

[Application of the scrotal axial skin flap in hypospadias repair].

OBJECTIVE: To present a new and reliable method for treatment of failed hypospadias repair. METHOD: The scrotal axial skin flap based on anterior scrotal vessels was designed and used in reconstruction of the urethra. 7 patients with failed hypospadias repair have been treated with this method since 1996. RESULT: There was no any complication in all the patients. CONCLUSION: The advantages of this method are that the flap has good blood supply and the potentiality of growth. It is suitable for treatment of hypospadias, especially the failed hypospadias repair.

Adolescent↗

PubMed2000

[Repair of rectovaginal fistula using pudendal-thigh flap pedicled on the obturator artery].

OBJECTIVE: This is to introduce a new method for repair of rectovaginal fistual. METHODS: On the basis of an anatomical study a new type of the pudendal-thigh flap pedicled on the obturator artery has been designed to repair rectovaginal fistual. RESULTS: 4 patients were treated with this method. All flaps survived and the fistula between vagina and rectum was closed primarily. CONCLUSIONS: The advantages of the pudendal-thigh flap pedicled on the obturator artery include: 1. Good blood supply; 2. Relative thin and hairless; 3. Perfect hiding of the donor site. We think that it is one of the best methods of rectovaginal fistula repair.

Adult↗

PubMed2000

[Lower lid blepharoplasty by using the principles of plastic surgery and the technique of orbital fat release].

OBJECTIVE: To create a new method for lower lid blepharoplasty in order to prevent the complication of lower lid ectropion after the operation. METHODS: Eight patients with 16 eyelids were undergoing the lower lid blepharoplasty with the use of plastic surgery principles and the technique of orbital fat release. The following-ups were carried out in each patient. RESULTS: Eight patients with 16 eyelids were treated with the above-mentioned technique. The satisfactory results were achieved with good appearance. CONCLUSION: The above-mentioned technique is a safe, simple and effective method for the lower lid blepharoplasty.

Adult↗

PubMed2000

[Leaching loss of nitrate from semiarid area agroecosystem].

A 6 years lysimeter experiment shows that an obvious nitrate leaching even occurred in semiarid area agroecosystem. The leaching loss was positively related to precipitation, and had a signficant difference among years with different precipitation. The application rate of N fertilizers determined the amount of leaching loss, but no obvious difference was found between urea and ammonium bicarbonate. Different depth of soil had different water storage, and therefore, had different leached amounts. Summer fallowing could increase the potential nitrate leaching loss.

Crops, Agricultural↗

PubMed2000

[Effect of AM fungi on water and nutrition status of corn plants under salt stress].

Under NaCl stress, the dry matter production of corn plants inoculated with or without arbuscular mycorrhizal (AM) fungus (Glomus mosseae) was decreased, but the decrement for non-mycorrhizal plants was 10% higher than that for mycorrhizal ones. Under salt stress condition, the dry weights of root system and aboveground part of mycorrhizal corn and its leaf water potential were higher than those of non-mycorrhizal corn, while the proline content of mycorrhizal corn was less than that of non-mycorrhizal corn. The contribution of hypha to P uptake of plants decreased from 45.3% to 42.6%, while the effect of AM fungi on plant growth increased from 30.9% to 63.5% under salt stress condition. The above-mentioned results indicated that the mechanism that AM fungi enhance the salt-resistance of corn is related with the improvements of water and P nutrition conditions. Meanwhile, it was found whether under salt stress or not, the ratio of P accumulation of root system to aboveground part of mycorrhizal corn was higher than that of non-mycorrhizal corn, indicating that the infection of AM fungi changed the P distribution pattern in plant bodies, which is beneficial to increase the salt-resistance of plants.

Ecosystem↗

PubMed2000

Platelet-derived growth factor and basic fibroblast growth factor immunolocalized in proliferative retinal diseases.

OBJECTIVE: To study the role of platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) in the development of proliferative vitreoretinopathy (PVR). METHODS: Immunohistochemical localization was performed on frozen sections of the epiretinal or subretinal membranes from 21 PVR patients using! monoclonal antibodies against PDGF and bFGF and the streptavidin peroxidase system. RESULTS: PDGF was expressed in 15 of 21 specimens (71.4%), and bFGF was expressed in 14 specimens (66.7%). Different cell density was seen in different types of epiretinal membranes. The cell density of vascular membranes induced by PDR and Eales disease was the highest (> or = 61 cells/field, x 1000); nonvascular membranes induced by PVR or traumatic PVR had moderate cell density (31-60 cells/field); and the macular membrane had the lowest cell density (< or = 30 cells/field). CONCLUSION: The presents of PDGF and bFGF in PVR tissues suggest that PDGF and bFGF may play an important role in the development of PVR.

Epiretinal Membrane↗

PubMed2000

Screening for mt-DNA mutations in optic neuritis of unknown cause.

OBJECTIVE: To investigate mitochondrial DNA (mt-DNA) mutations in optic neuritis of unknown cause (ONUC) and to assess the practical value of mt-DNA mutation detection in etiologically and differentially diagnosing ONUC. METHODS: Thirty patients with ONUC were screened for mt-DNA mutations of nt11778, nt3460 and nt15257 by using SSCP, mutation-specific primer PCR and sequencing. RESULTS: mt-DNA mutations were found in twelve of thirty ONUC patients. All of the mutations were at nt11778 position, but no one at nt3460 and nt15257. CONCLUSIONS: Forty percent (12/30) of ONUC patients were caused by an mt-DNA mutation. Combined with other routine measures, screening for mt-DNA mutations in ONUC patients is of great significance in diagnosing ONUC etiologically and differentially.

Adolescent↗

PubMed2000

Comparison of computer-photoscreening with non-cycloplegic retinoscopy for amblyopiogenic risk factors in children.

OBJECTIVE: To determine the sensitivity and specificity of using a computer-photoscreener and non-cycloplegic retinoscopy in the detection of amblyopiogenic factors in nine to fifty months old infants and children. METHODS: Three hundred children, nine to fifty months old, were screened with the computer-photoscreener and non-cycloplegic retinoscopy. With a blinded standardized clinical assessment as the standard, an overall comparison of the sensitivity of and specificity results obtained with the two techniques was made. Photoscreen images on the computer monitor screen were reviewed and analyzed immediately by two independent observers for indicators of amblyopiogenic risk factors. Simultaneously, the results were compared to the findings of a full ophthalmologic examination. RESULTS: The computer-photoscreener revealed a sensitivity of 94.6% and specificity of 90.1%, and the non-cycloplegic retinocopy revealed a sensitivity of 85.7% and specificity of 81.0% for the detection of amblyopiogenic risk factors, including hyperopia (+2.75 D or more), myopia (-1.50 D or more), astigmatism (1.75 D or more), anisometropia (2.00 D or more), ocular misalignment (5 degrees or more), and media opacity (1.5 mm or more). CONCLUSIONS: The computer-photoscreener offers an opportunity to identify problems that limit vision, and could provide a feasible and sufficiently reliable screening technique in infants and preschool children to be screened successfully for amblyopiogenic risk factors.

Amblyopia↗

PubMed2000

[Twelve cases of vaginal reconstruction using neurovascular pudendal-thigh flaps].

OBJECTIVE: To summarize the experience in vaginal reconstruction using neurovascular pudendal-thigh flaps. METHODS: The pudendal-thigh flaps lateral to labia majora with the external branches of labial posterior blood vessels in the pedicle were elevated and brought to the midline through tunnels formed under labia majora. The two flaps were then sutured together to create a new vagina. Flap size varied from 9 cm x 4 cm to 14 cm x 5 cm. RESULTS: In twelve cases aged 14 to 44 years including congenital absence of vagina, testicular ferminization syndrome and transsexual patients a new vagina was constructed with neurovascular pudendal-thigh flaps. One patient developed complete necrosis of unilateral flap, followed by formation of rectovaginal fistula. In other patients the flaps all survived and the neovagina was spacious and quite deep. CONCLUSION: The vaginal reconstruction using pudendal-thigh flaps is one of the best methods of vaginoplasty. The technique is simple and reliable. The flap has good blood supply and no stents or dilators are needed after operation. The donor site is hidden with little secondary deformity. The neovagina has a natural angle for intercourse and is sensible.

Adolescent↗

PubMed2000

[Nasal or oranasal face mask mechanical ventilation in the treatment of acute respiratory distress syndrome].

OBJECTIVE: To Evaluate the effect of nasal or oranasal face mask mechanical ventilation (FMMV) in the treatment of patients with acute respiratory distress syndrome(ARDS). METHODS: 16 ARDS patients were separated into two groups: infection group and non-infection group. The former had 6 cases with pneumonia and 1 case with sepsis; the later had 5 cases with multiple fracture, 2 with operation of intestines obstruction, 1 with operation of spleen rupture, 1 with hepatectomy. In Infection group, the respiratory rate(RR) was (46 +/- 5) times/min, the arterial blood pH 7.49 +/- 0.05, CO2 partial pressure(PaCO2) was (32 +/- 4) mm Hg, and oxygenation index (OI) (144 +/- 23) mm Hg. In non-infection group, the RR, pH, PaCO2, OI was (41 +/- 6) times/min, 7.49 +/- 0.13, (32 +/- 5) mm Hg, (156 +/- 51) mm Hg. All patients were linked with ventilator via nasal or ornasal mask. Pressure support ventilation (PSV) and positive end-expiratory pressure (PEEP) were selected. RESULTS: All patients successfully received FMMV. In infection group, RR and OI returned to (45 +/- 7) times/min (P > 0.05) and (195 +/- 30) mm Hg(P < 0.05) respectively after 2-8 hours via FMMV. But in non-infection group, the RR and OI were (35 +/- 4) times/min (P < 0.05) and (228 +/- 90) mm Hg(P < 0.05). 2 cases(29%) in infection group and 8 cases(89%) in non-infection were successfully weaned from FMMV. CONCLUSION: FMMV could be as the first choice in ARDS patients without infection, and airway intubation should be given in infectious patients as early as possible.

Acute Disease↗

PubMed2000

[Laser-induced fluorescence (LIF) spectrum of colorectal cancer in vivo].

OBJECTIVE: To study the LIF spectrum of colorectal cancer, adenomas, chronic colitis and normal colon tissue in vivo, with special emphasis on precancerous lesions. METHODS: A nitrogen laser (wavelength 337 nm) beam was introduced through endoscopic colonoscope and the fluorescence emission was recorded. An optical multichannel analyzer (OMA III) was used to analyze the fluorescence emission spectrum. A total of 83 patients was examined. RESULTS: The emission spectrum of LIF recorded on colorectal cancer and normal tissue showed significant differences in intensity and shape. (1) The normal tissue had higher intensity than that of cancer tissue. (2) The main peak wavelength of cancer moved to the red. (3) The minor peak of the cancer tissue fell more slowly than that of the normal tissue. Intensity of the main peak (x1), intensity ratio of 400 to 530 nm (x2) and the integrated LIF intensity (350-600 nm) (x3) were used as parameters to obtain an equation. The sensitivity and specificity of LIF for diagnosis of colorectal cancer was 83.3% and 94.4%, respectively. In 87.1% of moderate and severe dysplastic adenomatous polyps, the fluorescence spectrum was abnormal. CONCLUSION: In vivo, the LIF spectrum can be used to distinguish colorectal cancer from normal colon, especially from dysplasia. It plays an important role in the early diagnosis of colorectal cancer.

Adult↗