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Biomedical subjects

L Fan

Publications and source records attributed to L Fan.

At least 127 records · Page 7Linked to original sources
PubMed1997

[The characteristics of labour course and perinatal prognosis in cases of fetal persistent occiput-transverse position and persistent occiput-posterior position].

OBJECTIVES: To study the characteristics of the labour course and perinatal prognosis in cases of fetal persistent occiput-transverse position (POTP) and persistent occiput-posterior position (POPP). METHODS: All the cases, delivered with POTP and POPP in or hospital from Nov, 1995 to July 1996 were analyzed retrospectively. RESULTS: In abnormal fetal occipital position group, the following indices were significantly higher than those of normal group: fetal macrosomia, uterine inertia, and duration of each labour course. The speed of descending of presentation was obviously slower. The incidence of abnormal labour course was markedly increased. The rate of operative delivery was significantly higher. The total rate of operative delivery was 82.81% in the POTP group, and 92.31% in the POPP group. The incidence fetal hypoxia and neonatal asphyxia was markedly high in the abnormal occiput group. CONCLUSIONS: The POTP and POPP are major cases of dystocia. If management is unsuitable, perinatal prognosis will be poor.

Adult↗
PubMed1996

Activation of metabotropic glutamate receptor subtype mGluR1 contributes to post-traumatic neuronal injury.

The role of phospholipase C-coupled (group I) metabotropic glutamate receptors (mGluR1 and mGluR5) in post-traumatic neuronal injury was examined using rat in vivo and in vitro models. Traumatic injury to mixed neuronal/glial cultures induced phosphoinositide hydrolysis and caused neuronal death. Pharmacological blockade of group I receptors significantly reduced these effects in vitro and decreased neurological deficits as well as neuronal loss produced by traumatic brain injury in vivo. In contrast, activation of group I receptors by a specific agonist in vitro exacerbated post-traumatic neuronal death in a dose-dependent manner. Antisense oligodeoxynucleotide directed to mGluR1, but not to mGluR5, was neuroprotective in vitro, although each oligodeoxynucleotide reduced the respective receptor-stimulated accumulation of inositol phosphates to a similar degree. Together, these findings suggest that activation of mGluR1 contributes to post-traumatic neuronal injury and that mGluR1 antagonists may have therapeutic potential in brain injury.

Animals↗
PubMed1996

Association of human papillomavirus type 11 DNA with squamous cell carcinoma of the tongue.

A 47-year-old man with a history of a benign papilloma of the tongue 5 years earlier was treated for a squamous cell carcinoma of the tongue with surgical resection. An analysis of the tumor DNA using several methods showed the presence of human papillomavirus (HPV) type 11 sequences that migrated with the high molecular weight cellular DNA, suggesting integration of viral DNA into the cellular genome. A segment of the HPV DNA was cloned from the lesion and shown to be similar to prototype HPV 11 DNA, except for some variability in the viral long control region. The proviral DNA contained part of the L1 region, all of the viral long control region, the entire E6 and E7 open-reading frames, and at least a portion of the E1 region; the E4 region appeared to be deleted. The integration sites of the HPV DNA could not be specifically identified. An analysis of the p53 tumor suppressor gene region of the tumor DNA showed no evidence of mutation. These results suggest that the HPV 11 DNA may have had a role in the origin of the cancer in this patient.

Blotting, Southern↗
PubMed1996

Experimental brain injury induces differential expression of tumor necrosis factor-alpha mRNA in the CNS.

In the present study, we examined the expression of tumor necrosis factor-alpha (TNF-alpha) mRNA i specific brain regions following experimental lateral fluid percussion traumatic brain injury (TBI) in rats. Adult Sprague-Dawley rats (n = 42) were anesthetized with sodium pentobarbital (60 mg/kg, i.p.) and subjected to lateral fluid percussion brain injury of moderate severity (2.4 atm.) centered over the left temporoparietal cortex, or 'sham' treatment (anesthesia and surgery without injury). Animals were killed by decapitation at 1, 6 or 24 h post injury, brains removed, and tissue samples of left (injured) parietal cortex (LC), right parietal cortex (RC), left adjacent cortex (LA), right adjacent cortex (RA), left hippocampus (LH) and right hippocampus (RH) were prepared. Total RNA was isolated and Northern blot hybridization was performed. TNF-alpha mRNA is expressed as the percent relative radioactivity of macrophage (positive control) RNA. In sham or naive animals, no consistent changes in expression of TNF-alpha mRNA were observed in any of the six brain areas at any times (less than 5%). A marked increase of TNF-alpha mRNA expression was observed in LH (104 +/- 17, P < 0.05 compared with sham), LC (105 +/- 21, P < 0.05) and LA (69 +/- 8, P < 0.01) in the traumatized hemisphere 1 h following injury. An increased TNF-alpha mRNA expression was also observed in LH (46 +/- 8, P < 0.05), LC(30 +/- 3, P < 0.01) and LA(32 +/- 3, P < 0.01) at 6 h which resolved by 24 h following injury. In the contralateral hemisphere, expression of TNF-alpha mRNA was increased in RH (46 +/- 2, P < 0.01) at 1 h and in RA (26 +/- 6%, P < 0.05) at 6 h. These results indicate that following parasagittal fluid percussion brain injury, the temporal expression of TNF-alpha mRNA is altered in specific brain regions, including those of the non-traumatized hemisphere. Post-traumatic alteration in gene expression of TNF-alpha might play an important role in both the acute and regenerative response to CNS trauma.

Animals↗
PubMed1996

The Dai minority population of southwest China: heterogeneity of DR2-associated HLA-DRB1,DRB5,DQA1, and DQB1 haplotypes.

HLA-DR2 is the most common DR specificity (60.3%) identified in the Dai minority population of Xishuangbanna, Yunna Province, China. We characterized the DRB1, DRB5, DQA1, and DQB1 alleles of 44 unrelated DR2-positive individuals, 11 of whom (15%) were DR2 homozygous. Four DRB1 and four DRB5 alleles encoding DR2 were identified in this population. The most frequent DR2-associated DRB1 alleles were *1602 (gf = 0.164) and *1502 (gf = 0.151). DRB1*1501 (gf = 0.048) and a new allele designated DRB1*1504 (gf = 0.014) were also detected, but *1601 and *1503 were absent. The most frequent DR2-associated DRB5 alleles were *0101 (gf = 0.233) and *0102 (gf = 0.110). Nine different DR2-associated DR/DQ haplotypes were identified. The two most common DR2 haplotypes were DRB1*1602, DRB5*0101, DQA1*0102, DQB1*0502 (hf = 0.142) and DRB1*1502, DRB5*0102, DQA1*0101, DQB1*0501 (hf = 0.075). The new DRB1*1504 allele was found on a single haplotype: DRB1*1504, DRB5*0101, DQA1*0102, DQB1*0502 (hf = 0.017). The Dw2, Dw12, Dw21, and Dw22 haplotypes, present in many other Asian and Mongoloid populations, were not identified in this unique group. However, the Dai minority population is characterized by a relatively large number of diverse DR2 haplotypes and a new DRB1 allele encoding DR2.

China↗
PubMed1996

Differentiation between emboli and artefacts using dual-gated transcranial Doppler ultrasound.

It is well documented that transcranial Doppler ultrasound has the ability to detect cerebral emboli. During intraoperative patient monitoring studies, many signals due to artefact (probe motion, patient movement or surgical manipulation) are also detected and can be difficult to distinguish from genuine embolic events. We have constructed a Doppler system that can simultaneously range-gate at two separate depths, in order to test the hypothesis that it should be possible to distinguish between emboli and artefact by comparing the signal from the two separate regions within the vessel. The classification algorithm is based on the principle that emboli propagate with blood motion (whereas artefacts do not) and thus will be detected sequentially at different depths along the insonated cerebral artery. One hundred thirty-eight (presumed) embolic and 170 artefact signals were analysed. The median (interquartile range) gate separation was 10.01 mm (7.41-10.78 mm). The time delay between detection of embolic signals in the two channels was 11.04 ms (6.24-16.41 ms, but was only 0.08 ms (-0.48(-)+0.64 ms) for artefact (p < 0.0001). Dual-gated Doppler ultrasound is a conclusive and independent method that differentiates emboli from artefact. Incorporation of this system for long-term monitoring may eliminate the need for an experienced observer to be present.

Artifacts↗
PubMed1996

Heat shock response of Trichinella spiralis and T. pseudospiralis.

Heat shock proteins (HSPs) were documented for the first time in both somatic extracts and excretory/secretory (ES) products of the infective-stage larvae of Trichinella spiralis and T. pseudospiralis. Larvae recovered from muscles of infected mice were heat shocked at 37, 40, 43 and 45 degrees C in RPMI 1640 medium containing L(-)[35S]methionine. Somatic extracts and ES products of heat-shocked worms were then analysed by SDS-PAGE, autoradiography and laser densitometry. Prominent bands of HSPs were observed at 43 degrees C which is the optimal heat shock temperature. The major HSPs in somatic extracts of T. spiralis were 20, 47, 50, 70, 80 and 86 kDa. When the temperature was increased from 37 to 43 degrees C, the greatest increase in absorbance was observed in HSPs 70 and 86. In vitro translation of mRNA in a nuclease-treated rabbit reticulocyte lysate system showed an increase in the synthesis of the 80 kDa protein. This suggests that the production of HSP 80 is regulated at the transcriptional level. The major HSPs in the ES products were 11, 45, 53 and 64 kDa. In T. pseudospiralis, the major HSPs in the somatic extracts were 20, 26, 31, 50, 53, 70, 80 and 86 kDa, and in the ES products, 11, 35, 37, 41 and 64 kDa.

Animals↗
PubMed1996

Enhanced natriuretic response to intrarenal infusion of atrial natriuretic factor during ovine pregnancy.

Volume-loading and intravenous infusion studies have suggested that the natriuretic response of atrial natriuretic factor (ANF) is blunted or unaltered during pregnancy, but these findings may be influenced by changes in peripheral metabolism or clearance. To better define the direct renal actions of ANF, three doses (0.3, 1.5, and 3.0 pmol.kg-1.min-1) of ANF were infused directly into the renal artery of nonpregnant (n = 7) and 115- to 135-day pregnant (n = 6) unilaterally nephrectomized conscious sheep. Each dose was administered on a separate day according to a protocol that consisted of two 20-min control periods, two 20-min ANF infusions, and three 30-min recovery periods. The levels of basal mean arterial pressure averaged 86 +/- 25 mmHg and were similar and constant throughout all protocols in nonpregnant and pregnant ewes. Glomerular filtration rate (GFR) and renal blood flow (RBF) were increased during pregnancy, but GFR, RBF, and fractional proximal tubular reabsorption were not significantly altered by infusion of ANF. Nonpregnant sheep exhibited a selective renal response that was limited to an increase in urinary sodium excretion (UNaV). Pregnant sheep exhibited a selective renal response that included increases in UNaV and urine flow rate produced by suppression of distal sodium and, presumably, fluid reabsorption. The natriuretic and diuretic response of pregnant sheep was much greater than that of nonpregnant sheep despite a smaller proportional increment in intrarenal ANF concentration. These data suggest that the ovine renal response to ANF is limited to actions on the distal tubule that are enhanced during pregnancy.

Absorption↗
PubMed1996

[An experimental study of regional spontaneous portasystemic shunt in cirrhotic rats].

CCl4 induced splenic portasystemic shunt (SPSS) was measured in 11 CCl4-induced cirrhotic rats and 10 controls, and mesenteric shunt (MPSS) was measured in 11 controls. 125I labeled albumin microspheres was used as nuclear markers for measurement of shunting rate. It was found that, portal resistance, free portal pressure, wedged hepatic venous pressure, portahepatic venous pressure gradient were all elevated markedly in cirrhotic rats, while the volume of portal flow had no significant difference between the two groups. SPSS and MPSS were higher remarkably those that in the normal controls, and SPSS was greater than MPSS significantly. It suggested that splenogastric venous bed is the main area for compensatory shunt and also the dangerous site of bleeding. Portaazygous disconnection is the operation of choice for control of bleeding. However it could impair the mechanism of spontaneous shunting compensation seriously. Disconnection operation combined with splenorenal shunt seems to be a reseasonable consideration.

Animals↗
PubMed1996

[Effect of HE-NE laser acupuncture on the spleen in rats].

The splenic sinuses, lymphocytes and antigen presenting cells in the spleen of rat stimulated by He-Ne laser acupuncture were observed by using TEM to investigate the ultrastructural changes of them. The width of endothelial interstice was increased, hence a lot of blood cells oozed out of the splenic sinuses. There were numerous activated T cells which contained abundant mitochondria and ribosome in the periarterial lymphatic sheaths. The B cells were gradually differentiated into large lymphocytes, immature and mature plasmatic cells with a lot of endoplasmic reticula. They were prominently increased in the splenic nodules. The macrophages had short processes with numerous folds and microvilli and tended to neighboring lymphocytes. The nucleus pores were increased. There were a lot of vacuoles, phagosome and mitochondria were closed to macrophages and lymphocytes. In conclusion the activities of the cellular immunity and humoral immunity were enhanced by laser.

Acupuncture Points↗
PubMed1995

Experimental brain injury induces expression of interleukin-1 beta mRNA in the rat brain.

Cytokines have been shown to be induced following a variety of central nervous system (CNS) insults, and may play a role in the pathophysiological sequelae of CNS injury. In the present study, we characterized the regional expression of interleukin-1 beta (IL-1 beta) mRNA in specific brain regions following experimental lateral fluid-percussion traumatic brain injury (TBI) in rats. Adult Sprague-Dawley rats (n = 42) were anesthetized with sodium pentobarbital (60 mg/kg, i.p.) and subjected to lateral fluid-percussion brain injury of moderate severity (2.4 atm.) centered over the left parietal cortex, or 'sham' treatment (anesthesia and surgery without injury). Animals were sacrificed at 1, 6 and 24 h post injury, brains were removed, and tissue samples of left (injured) parietal cortex (LC), corresponding area in the contralateral right cortex (RC), cortex adjacent to injured parietal cortex (LA), corresponding adjacent area in the right cortex (RA), left hippocampus (LH) and right hippocampus (RH) were prepared. Total RNA was isolated and Northern blot hybridization was performed and the quantity of brain tissue IL-1 beta mRNA is presented as percent relative radioactivity of IL-1 beta positive macrophage RNA which was loaded on same gel.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Cytotoxicity, DNA adduct formation and DNA repair induced by 2-hydroxyamino-3-methylimidazo[4,5-f]quinoline and 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine in cultured human mammary epithelial cells.

2-Amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) are heterocyclic amines (HAs) found in cooked meats. Both compounds are mammary gland carcinogens in rats. The initiation of carcinogenesis by the HAs is believed to be associated with their DNA adduct formation that occurs after metabolic activation of the parent amines via cytochrome P-450-mediated N-hydroxylation and esterification. To assess the capacity of the human mammary epithelium to metabolically activate the HAs, we used the 32P-postlabeling method to measure the levels of DNA adducts in a culture of human mammary epithelial cells exposed to IQ, PhIP or their N-hydroxylamine metabolites. Whereas 50 microM parent amines did not form detectable levels of DNA adducts in cultured human mammary epithelial cells after 24 h incubations, concentrations as low as 1 microM N-hydroxylamines produced detectable levels of adducts after 2 h incubations. N-Hydroxy-PhIP formed higher adduct levels than N-hydroxy-IQ at all concentrations tested. For example, following a 2 h incubation at 50 microM, adduct levels (per 10(7) nucleotides) were 674 and 16 for N-hydroxy-PhIP and N-hydroxy-IQ, respectively. At similar initial adduct levels (10-11/10(7) nucleotides), 60-80% of IQ- and PhIP-DNA adducts were removed after 24 h, indicating that the mammary epithelial cell culture showed efficient repair of HA adducts. Whereas neither IQ nor PhIP was cytotoxic, both N-hydroxy-IQ and N-hydroxy-PhIP were cytotoxic as assessed by a dose-dependent inhibition of colony formation. After exposure to 0.1, 1, 10 or 50 microM N-hydroxy-PhIP (or N-hydroxy-IQ), colony formation was 103 (94), 84 (74), 37 (29) and 3 (2)% of the control values, respectively. Only N-hydroxy-PhIP (at 10 and 50 microM), however, was cytotoxic as assessed by the MTT cell survival assay (which measures the capacity of mitochondria to metabolize a tetrazolium salt). The ability of the N-hydroxylamines to form DNA adducts and to be cytotoxic in a culture of human mammary epithelial cells may implicate these metabolites as proximate carcinogenic forms of IQ and PhIP in the human mammary gland. However, whether there are inter-individual differences in N-hydroxylamine metabolism, adduct formation and repair in human mammary epithelial cells requires further study. The results from this study support the usefulness of cultured human mammary epithelial cells for studies on the genotoxicity and metabolism of the N-hydroxylamines of HA food mutagens.

Breast↗
PubMed1995

Effects of angiotensin II on plasma atrial natriuretic factor in nonpregnant and pregnant ewes.

The release of atrial natriuretic factor (ANF) is primarily determined by atrial stretch, but may also be modulated by circulating angiotensin II (AngII). During pregnancy, the circulating concentrations of both ANF and AngII are increased. To further define possible effects of AngII on ANF release, four doses of AngII (0.5, 5, 20, 40 ng.kg-1.min-1) were intravenously infused into five nonpregnant and five pregnant (105-140 days of gestation) ewes alone and during the simultaneous infusion of sodium nitroprusside at doses sufficient to abolish the pressor effects of AngII. Mean arterial pressure (MAP) was increased from 80 +/- 2 to a maximum of 121 +/- 5 mmHg (1 mmHg = 133.3 Pa) in nonpregnant ewes (p < 0.01) and from 79 +/- 2 to 116 +/- 4 mmHg in pregnant ewes (p < 0.01) over the range of AngII infusion. MAP was unaltered during AngII plus nitroprusside infusion, averaging 78 +/- 3 mmHg in nonpregnant ewes and 80 +/- 2 mmHg in pregnant ewes. Basal ANF was higher (p < 0.01) in pregnant sheep than in nonpregnant sheep. With AngII infusion alone, plasma ANF was increased from 13 +/- 2 to 42 +/- 4 fmol/microL in nonpregnant ewes (p < 0.01) and from 23 +/- 5 to 72 +/- 16 fmol/microL in pregnant ewes (p < 0.01). However, during AngII plus nitroprusside infusion, the increases in plasma ANF observed were completely abolished in both nonpregnant and pregnant ewes.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1995

Control of atrial natriuretic factor by right and left atrial distension in pregnant sheep.

Previous studies of the atrial stretch-atrial natriuretic factor (ANF) relationship during pregnancy have employed volume expansion and measured only right atrial pressure (RAP). Consequently, we studied nonpregnant (n = 7) and 115- to 125-day pregnant (n = 7) sheep and assessed the ANF response to changes of RAP and left atrial pressure (LAP) induced by graded balloon inflation. Ewes prepared with vascular catheters and atrial balloons were studied after recovery from preparatory surgical procedures. The basal levels of mean arterial pressure (MAP, 83 +/- 3 mmHg), RAP (2.1 +/- 0.7 mmHg), LAP (4.7 +/- 0.9 mmHg), and heart rate (HR, 102 +/- 6 beats/min) were similar in nonpregnant and pregnant sheep. Pregnancy also resulted in elevation of ANF concentration from 25 +/- 6 to 57 +/- 4 fmol/ml. With right atrial distension, the RAP-ANF relationships were similar in both nonpregnant and pregnant sheep, with a 10-mmHg increase in RAP increasing ANF by an average of 95 +/- 9 fmol/ml. In nonpregnant sheep, the LAP-ANF relationship was more responsive than RAP-ANF because a 10-mmHg increase in LAP resulted in a 193 +/- 10 fmol/ml increase in ANF. Moreover, during pregnancy, the LAP-ANF relationship was significantly more sensitive because a 10-mmHg increase in LAP resulted in a 433 +/- 15 fmol/ml elevation of ANF. These data demonstrate that plasma ANF levels are more responsive to distension of the left atria than to the right. More importantly, the ANF response to left, but not right, atrial distension is enhanced by pregnancy.

Analysis of Variance↗
PubMed1995

Interpretation of embolic phenomena during carotid endarterectomy.

BACKGROUND AND PURPOSE: Air and particulate emboli are a major source of morbidity during carotid endarterectomy (CEA); however, amplitude overload and poor time resolution have restricted the ability of transcranial Doppler ultrasound to differentiate between the two. METHODS: We have now overcome these two limitations by (1) rerouting embolic signals away from the audio frequency amplifier to avoid amplitude overload and (2) substituting the Wigner distribution function for the fast Fourier transform to improve time and frequency resolution. Thus, we can now accurately determine embolic duration and embolic velocity, the product of which is the sample volume length (SVL). This measurement represents the physical distance over which an embolic signal can be detected. The underlying hypothesis was that air reflected more ultrasound and would therefore be detected over a greater SVL. RESULTS: The median SVL (interquartile range) for 75 in vitro air emboli was 1.97 cm (range, 1.70 to 2.35) compared with 0.27 cm (range, 0.16 to 0.43) for 185 particulate emboli detected during the dissection phase of CEA. Off-line analysis on an additional 560 embolic signals detected during different phases of CEA suggested that 46 of 143 (32%) of emboli immediately after shunt insertion were particulate, as were 19 of 33 (58%) occurring during shunting, 28 of 78 (36%) after restoration of flow in the external carotid artery, 23 of 251 (9%) after restoration of flow in the internal carotid artery, and 55 of 55 (100%) of those emboli detected during the early recovery phase. CONCLUSIONS: This development provides objective physical criteria upon which embolus characterization (particulate/air) can be based. This could have major implications for future patient monitoring with respect to modification of surgical technique and pharmacological intervention.

Embolism, Air↗
PubMed1995

An appraisal of equilibrium and disequilibrium models of population migration.

"This article [discusses] the basic assumptions of the equilibrium and disequilibrium models and their pertinent discussion. In addition, the article examines the conditions under which the two types of models apply in different socioeconomic situations, while paying special attention to the assumptions selected for research of migration in developing countries especially at a time when they begin to move toward a market economy."

Demography↗