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Biomedical subjects

J Lin

Publications and source records attributed to J Lin.

At least 325 records · Page 18Linked to original sources
PubMed1998

Quantitation and regulation of pyroglutamyl peptidase II messenger RNA levels in rat tissues and GH3 cells.

The distribution of the mRNA of the specific thyrotropin-releasing-hormone (TRH)-degrading enzyme pyroglutamyl peptidase II (EC 3.4.19.6) in rat tissues and brain regions and its regulation in rat tissues and in GH3 cells was studied by a reliable and quantitative solution hybridization ribonuclease protection assay. The distribution of pyroglutamyl peptidase II mRNA levels was uneven with the highest level of mRNA found in brain. Within brain the distribution of pyroglutamyl peptidase II mRNA was heterogeneous. A single dose of T3 markedly increased the level of pyroglutamyl peptidase II mRNA in the pituitary (p < 0.01) and in the liver (p < 0.05). In GH3 cells, exposure to T3 at concentrations from 10(-10) to 10(-6) M for time periods of 2-24 h, did not change pyroglutamyl peptidase II mRNA levels. Acute administration of TRH to rats had no effect on pyroglutamyl peptidase II mRNA levels. By contrast, TRH down-regulated pyroglutamyl peptidase II mRNA in GH3 cells. A similar effect was produced in GH3 cells by activators of protein kinase C. These studies reveal fundamental differences in the mechanism of regulation of pyroglutamyl peptidase II mRNA in pituitary and in GH3 cells. Elevation of pyroglutamyl peptidase II mRNA in liver by T3 suggests that this organ is the source of the enzyme in serum.

Aminopeptidases↗
PubMed1998

Increase of mucous glycoprotein secretion by tumor necrosis factor alpha via a protein kinase C-dependent mechanism in cultured chinchilla middle ear epithelial cells.

Tumor necrosis factor alpha (TNF-alpha), originally defined by its antitumoral activity, is now recognized as a polypeptide mediator of inflammatory and cellular immune response. Recent studies have demonstrated that TNF-(alpha exists in the fluid of otitis media with effusion and, therefore, suggested its possible role in the pathogenesis of mucus hypersecretion. In this study, the effects of TNF-alpha on mucous glycoprotein (MGP) secretion from cultured chinchilla middle ear epithelial cells were examined, and TNF-alpha was found to stimulate MGP secretion in a time- and concentration-dependent manner. The action of TNF-alpha on MGP secretion was significantly and dose-dependently inhibited by TNF-alpha monoclonal antibody; this finding is suggestive of its specificity on MGP secretion. The addition of the protein kinase C inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperidine (H-7) to the culture significantly blocked TNF-alpha-induced MGP secretion, while the calmodulin inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) did not. This suggests that TNF-alpha stimulates MGP secretion via a protein kinase C-dependent mechanism.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1998

Identification of trophoblast-specific regulatory elements in the mouse placental lactogen II gene.

Placental lactogen II, the major ligand for the PRL receptor during the second half of gestation in rodents, is synthesized specifically by placental trophoblast giant cells. A transient transgenic analysis has been used to localize the giant cell-specific regulatory region within the mouse placental lactogen II gene to sequences between -1340 and -2019 upstream of the transcriptional start site. More precise mapping of the regulatory elements has been accomplished by transfection of promoter constructs into Rcho-1 trophoblast cells, resulting in the characterization of two positive regulatory elements in the -1471 to -1340 region; two other regulatory elements have been implicated but not further characterized, a negative regulatory element between -2019 and -1778 and another positive element within the region from -1340 to -569. Both of the characterized positive regulatory elements are recognized by factors that are enriched in differentiated giant cells compared with proliferative trophoblasts, and these factors are either absent or at low levels in fibroblasts. The complexes that form on the two elements are distinct and neither element competes with the other for factor binding, thus implicating at least two different regulatory elements in late-gestational trophoblast giant cell-specific gene expression.

Animals↗
PubMed1998

Electromyographic investigation of masticatory muscles in unilateral cleft lip and palate patients with anterior crossbite.

OBJECTIVE: To evaluate the characteristics of masticatory muscle activity in operated unilateral cleft lip and palate (UCLP) patients with anterior crossbite compared with normal individuals. SUBJECTS: Sixteen male and 13 female Chinese patients with UCLP and anterior crossbite. Fifteen male and 13 female Chinese individuals without cleft abnormalities served as a control group. DESIGN: Electromyographic activity of the masseter muscles and anterior temporalis muscles was recorded bilaterally in different mandibular positions using bipolar surface electrodes. RESULTS: Compared to noncleft controls, patients with UCLP demonstrated (1) higher activation levels of masseter and temporalis muscles in the rest position, (2) lower potential function of masseter and temporalis, (3) inharmonious activity of the masticatory muscles during mandibular border movement, (4) a higher asymmetry index of the masseter and temporalis muscles, and (5) longer silent periods of the two muscles. CONCLUSIONS: The function of masticatory muscles is different in patients with UCLP with anterior crossbite. Muscle function should be considered when evaluating cleft patients for orthodontic treatment and orthognathic surgery.

Action Potentials↗
PubMed1998

Osteochondromalike parosteal osteosarcoma: a report of six cases of a new entity.

OBJECTIVE: Our purpose was to describe a rare juxtacortical bone sarcoma with deceptively benign, osteochondromalike histologic characteristics. We present criteria by which this low-grade malignant neoplasm can be distinguished from other benign and malignant surface lesions of bone with particular emphasis on the imaging features. MATERIALS AND METHODS: Six cases of a low-grade, chondroossifying parosteal sarcoma of bone were reviewed. Patients included four males and two females 11 months to 66 years old. Histologic findings from initial tumors and from recurrent tumors were reviewed. Two musculoskeletal radiologists analyzed the imaging studies, which included plain films, CT scans, MR images, and a bone scan. RESULTS: Histologically, the lesions were characterized by a thin layer of proliferating, periosteally derived spindle cells overlying a thin, low-grade malignant cartilage cap that underwent calcification, neovascularization, and conversion into benign bone and marrow fat. These lesions were unique in that the malignant elements were only at their periphery. All six cases were initially misdiagnosed as benign lesions on pathologic evaluation. In each patient, imaging revealed a "pasted-on" ossified surface lesion with an intact underlying cortex and no medullary involvement. In three cases, recurrent tumors had histologic appearances consistent with conventional parosteal osteosarcoma. Dedifferentiation, metastases, and death occurred in one of these three cases. CONCLUSION: To our knowledge, this surface lesion of bone has not been specifically described. Whether this tumor constitutes a distinct entity or is a specialized variant of parosteal osteosarcoma is unclear. Precise radiologic-pathologic correlation is essential for appropriate diagnosis and management.

Adolescent↗
PubMed1998

Upregulation of the vascular endothelial growth factor/vascular endothelial growth factor receptor system in experimental background diabetic retinopathy of the rat.

Vascular endothelial growth factor (VEGF) is a major contributor to retinal neovascularization. The possible participation of VEGF and its high-affinity tyrosine kinase receptors, flk-1 and flt-1, in early background diabetic retinopathy was studied in the streptozotocin-induced diabetic rat model of experimental retinopathy using in situ hybridization, blotting techniques, and immunohistochemistry. Diabetic retinopathy was assessed by quantitative morphometry of retinal digest preparations. The number of acellular capillaries increased 2.7-fold in diabetic animals with diabetes' duration of 6 months compared with nondiabetic controls. VEGF expression was not detectable by in situ hybridization in nondiabetic rats but was highly increased in the ganglion cell layer and in the inner and outer nuclear layers of retinas from diabetic animals. VEGF protein was extractable only from diabetic retinas, and a strong immunolabeling was detected in vascular and perivascular structures. Increased flk-1 and flt-1 mRNA levels were also found in the ganglion cell and both nuclear layers of diabetic samples only. Dot blot and Western blot analyses confirmed the increase in flk-1 mRNA and protein in diabetic retinas. Also, flk-1 immunoreactivity was associated with vascular and nonvascular structures of the inner retinas from diabetic animals. These data obtained from a rodent model in which retinal neovascularization does not occur support the concept that the VEGF/VEGF receptor system is upregulated in early diabetic retinopathy.

Animals↗
PubMed1998

Inhibition of in vitro growth of coliform bacteria by a monoclonal antibody directed against ferric enterobactin receptor FepA.

The ability of a murine monoclonal antibody that blocks the enterobactin ligand-binding site of the ferric enterobactin receptor FepA to inhibit the growth of coliform bacteria derived from a bovine intramammary infection (IMI) was determined in an iron-restricted medium. Bacterial isolates from bovine IMI in five herds were tested by the chrome azurol sulfonate assay to detect siderophore production. Each of the isolates of Escherichia coli (n = 25) and Klebsiella pneumoniae (n = 25) were positive for siderophore production. Each isolate expressed iron-regulated outer membrane proteins when grown in trypticase soy broth plus the iron chelator alpha-alpha'-dipyridyl. Immunoblots revealed that the monoclonal antibody recognized FepA that was expressed by each of the E. coli isolates (n = 25). Only 4 of 25 K. pneumoniae isolates produced FepA that reacted with the monoclonal antibody. This result coincided with the results of an in vitro growth assay. Growth of all E. coli isolates was significantly inhibited by the addition of monoclonal antibody to synthetic medium containing apolactoferrin. Antigenic variation in the enterobactin-binding site resulted in a low percentage of K. pneumoniae isolates that were inhibited by the monoclonal antibody. Inhibition of bacterial growth by the monoclonal antibody was dose-dependent. As little as 50 micrograms/ml of purified antibody had an inhibitory effect on bacterial growth in the synthetic iron-restricted medium. Monoclonal antibody specific for the enterobactin ligand-binding site of FepA inhibited the growth of E. coli that was isolated from bovine IMI.

Animals↗
PubMed1998

Immunization of cows with ferric enterobactin receptor from coliform bacteria.

The serum and milk immunoglobulin (Ig) G responses of lactating dairy cows were determined following immunization with ferric enterobactin receptor FepA. Escherichia coli 471 was cultured in iron-depleted medium, and outer membrane proteins were extracted by 2% N-lauroylsarcosine sodium salt and 2% Triton X-100. The FepA was isolated from the outer membrane proteins by ion-exchange chromatography. Twenty cows were assigned to four treatment groups of 5 cows blocked by breed and days in milk. Treatment groups were vaccinated with 100 micrograms of FepA, 500 micrograms of FepA, Escherichia coli J5 bacterin, or sterile phosphate-buffered saline. Primary immunization was at approximately 200 d in milk, and booster immunizations were given 14 and 28 d later. Serum and whey IgG titers to FepA in cows vaccinated with FepA were significantly higher than those from cows vaccinated with either E. coli J5 bacterin or phosphate-buffered saline. Serum and whey IgG titers to FepA were elevated by 14 d in cows vaccinated with FepA. Significant differences were not observed between doses of FepA. The degree of cross-reactivity of purified IgG from cows vaccinated with FepA to E. coli and Klebsiella pneumoniae isolates was significantly higher than that to a control isolate that lacked FepA production. Immunization with FepA elicited an immunological response in serum and milk.

Ammonium Sulfate↗
PubMed1998

[Experimental study of effects of anti-ovarian antibodies on ovarian histology and function].

OBJECTIVE: To investigate the effects of anti-ovarian antibodies (AOA) on ovarian histology and functions. METHODS: Rabbit antibodies against mice ovarian tissues were obtained by immunizing with mice ovarian extracts and purified. The effects of AOA on mice ovarian histology were examined under light and electronic microscope. In addition, changes of ovarian functions, including natural pregnant rate and pregnant mare serum gonadotropin (PMSG) + hCG induced ovulation rate and pregnant rate, were also observed. RESULTS: After treating with different doses of AOA pathological changes occurred in a variety of ovarian components, especially in zona pellucida and granulosa cells, which is more serious in high AOA level group than that in low AOA level group. The natural pregnant rate decreased to zero in both AOA groups. The ovulation and pregnant rate induced by PMSG-hCG were significant lower in both AOA groups than that in the control group especially in the high AOA level group. CONCLUSION: AOA may damage the ovarian tissues and reduce the ovulation and pregnant rate. The higher the AOA level, the more serious pathological changes and the poorer curative effects of PMSG-hCG may occur.

Animals↗
PubMed1998

[Determination of cellular and humoral immunity in mice of autoimmune ovarian failure].

OBJECTIVE: To determine cellular and humoral immunity in mice of autoimmune ovarian failure. METHODS: A mice model of autoimmune ovarian failure was established. The percentages of help T cell (CD4+) and suppressor T cell (CD8+), the ratio of CD4/CD8 and anti-ovarian antibody (AOA) were determined. RESULTS: No significant changes were found in CD4+ fraction, but the percentage of CD8+ was reduced and the ratio of CD4/CD8 increased. AOA was positive which was probably the cause of damage of the ovarian tissues, reduction of sex hormone secretion and impaired fertility. CONCLUSION: Autoimmune ovarian failure is correlated with the abnormal change of CD4/CD8 and the increase of B-lymphocytes function.

Animals↗
PubMed1998

[The effect of amlodipine, nifedipine and perindopril on insulin sensitivity and blood lipid of patients with essential hypertension].

OBJECTIVE: To investigate the effect of amlodipine, nifedipine and perindopril on insulin sensitivity(IS) and blood lipid of patients with essential hypertension(EH). METHODS: 105 EH patients were randomly divided into 3 groups: amlodipine group; nifedipine group; perindopril group. Treatment period lasted for 4 weeks. Before and after treatment, IS was measured by euglycemic insulin clamp technique with glucose metabolism rate (M) as an index of IS. RESULTS: Amlodipine, nifedipine and perindopril significantly reduced blood pressure compared with that before treatment(P < 0.01). In the EH patients with decreased IS, the M value (mg.kg-1.min-1) after the use of amlodipine, nifedipine and perindopril was higer than that before treatment (amlodipine: 6.6 +/- 1.5 Vs 4.6 +/- 0.6, P < 0.01; nifedipine: 5.2 +/- 1.2 Vs 4.4 +/- 0.6, P < 0.05; perindopril: 6.8 +/- 1.6 Vs 4.4 +/- 0.6, P < 0.01). The increase of M value(mg.kg-1.min-1), nifedipine (1.2 +/- 0.9) were significantly lower than that of amlodipine(2.1 +/- 1.1) and perindopril(2.4 +/- 1.5), P < 0.01, respectively, but no significant difference was found between amlodipine and perindopril(P > 0.05). CONCLUSION: Amlodipine and perindopril have beneficial effect on improving insulin sensitivity in EH patients with decreased insulin sensitivity. The effect of nifedipine on insulin sensitivity is lower than that of amlodipine and perindopril. Blood lipid is not significantly changed after short treatment.

Amlodipine↗
PubMed1998

[The effects of BDP on eosinophils in nasal secretions of the patient with allergic rhinilis].

The effects of beclomethasone dipropionate (BDP) on eosinophils in nasal secretions of the patients with allergic rhinilis was assaied under the laser scanning confocal microscopy and the technology of fluoresence. The scanning images displayed that fluoresence signal of the eosinophils intracellular RNA was significantly decreased after BDP treatment. The results showed that anti-inflammation funtion of BDP was realized by controlling the intracellular DNA translate to RNA.

Anti-Inflammatory Agents↗
PubMed1998

[Neurotoxicity of antibody against motoneuron on cultured rat cortical neurons].

OBJECTIVE: In order to determine the role of antibody against motoneuron in the process of neuronal death. METHODS: Cultured rat cortical neurons growing in serum-free medium, were employed to observe the effects of antibody against motoneuron (anti-SMN) on the survival of these cultured neurons. RESULTS: (1) Exposure of the cultures in serum-free medium to anti-SMN with dilution of 1:50 results in death of 31%-41% of neurons for 24 hours incubation, 50%-67% for 48 hours and above 90% after 72 hours. The neurotoxicity induced by anti-SMN was accompanied by concentration-dependent release of lactate dehydrogenase into the culture medium. Cultures exposed to normal rat IgG as controls exhibited no such sign. (2) The cultured neurons exposed to anti-SMN (1:200) expressed markedly higher levels of immunoreactive Calbindin-D28k especially after 48 hours incubation with it. There was a reduction in the number of acetylcholinesterase-positive neurons compared to the normal control. CONCLUSIONS: The anti-SMN could directly initiate the process of cortical neuronal death and this effect was independent of complement. The alteration of Calbindin-D28k immunoreactivity implied that calcium may be involved in the neurotoxicity induced by anti-SMN.

Acetylcholinesterase↗
PubMed1998

[The general survey for chondromalacia of 2,743 Chinese population].

OBJECTIVE: To evaluate the distribution of chondromalacia patella in Chinese population. METHODS: A random cluster sampling survey was performed covering 2,743 subjects varied in age, sex and occupation in 1995. RESULTS: The prevalence rate is 36.2%. The occurrence in women was higher than that in men (P < 0.01), while in the age group, 30 to 39 years was the highest being 55.8%. The prevalence rate in soldier being 47.5% was the highest among varied occupations. CONCLUSIONS: Our study is the first survey to be performed in a large number of Chinese population. This investigation may reflect the prevalence rate of chondromalacia patella in China.

Adolescent↗
PubMed1998

[Expression of IL-1 mRNA and its correlation with astrocytes and NOS-positive neurons in rat spinal cord following sciatic nerve injury].

OBJECTIVE: To study expression of Interleukin 1 (IL-1) and its correlation with astrocytes and nitric-oxide synthase (NOS)-positive neurons in rat spinal cord following sciatic nerve transection. METHODS: Using RT-PCR and immunohistochemistry methods. RESULTS: The experiments showed that IL-1 expression appeared with a low frequency at 3 days after the axontomy, while it could be markedly detectable on post-lesioned day 7 and 14. In normal controls and the spinal fragments without being involved in the injury, no signal of IL-1 mRNA expression was detected with the same condition. At 7 days after nerve injury, the lesioned side of spinal cord began to show strong glial fibrillary acidic protein (GFAP) immunoreactive astrocytes and induction of NOS in the motoneurons that are normally NOS-negative. Up to 21 days after operation, GFAP staining showed star-shaped astrocytes closely resembling the typical appearance of fibrous astrocytes and GFAP-immunoreactive profiles were often seen surrounding NOS-positive neurons. Analysis of the time course of IL-1 mRNA expression, appearance of NOS-positive neurons and changes of reactive astrocytes suggested a close relationship between them. CONCLUSIONS: IL-1, NO might function as important mediators between injured motoneurons and astrocytes.

Animals↗
PubMed1998

[Surgical management of closed injury of mitral valve: report of four cases].

OBJECTIVE: To show the experience in dealing with mitral valve injury caused by trauma. METHODS: Four cases of closed injury of mitral valve were treated. RESULTS: Two of the four patients presented ruptured chordae of mitral valve and were cured with annutoplasty plus repair of the chordae and mitral valve replacement respectively. One presented tearing of mitral valve leaf and pseudoaneurysm of the femoral artery, which were complicated by infective endocarditis. The patient was cured with emergency operation to repair the lesions and remove pseudoaneurysm and neoplasm in the mitral valve. Another patient, who received mitral valve replacement 8 years before, presented ruptured valve-hook of the prosthesis and died of acute heart failure without prompt operation. The diagnosis was confirmed by autopsy. CONCLUSIONS: The disease is easy to misdiagnose and once the diagnosis is established surgical intervention should be performed early. Emergency operation is necessary if acute heart failure occurs or infective endocarditis is complicated.

Adult↗