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Biomedical subjects

X M Lin

Publications and source records attributed to X M Lin.

15 recordsLinked to original sources
PubMed2005

Equilibrium morphology of face-centered cubic gold nanoparticles >3 nm and the shape changes induced by temperature.

Many of the unique properties of metallic nanoparticles are determined not only by their finite size but also by their shape, defined by the crystallographic orientation of the surface facets. These surfaces (and therefore the nanoparticles themselves) may differ in a number of ways, including surface atom densities, electronic structure, bonding, chemical reactivities, and thermodynamic properties. In the case of gold, it is known that the melting temperature of nanoparticles strongly depends on the crystal size and that the shape may alter considerably (and yet somewhat unpredictably) during annealing. In this work we use first principle calculations and a thermodynamic model to investigate the morphology of gold nanoparticles in the range 3-100 nm. The results predict that the equilibrium shape of gold nanoparticles is a modified truncated octahedron and that the (size-dependent) melting of such particles is preceded by a significant change in the nanoparticle's morphology.

Journal Article↗
PubMed2005

Distribution of sorbed phenanthrene and pyrene in different humic fractions of soils and importance of humin.

Contributions of fulvic-humic acids (FA/HA) and humin (HM) to sorption of phenanthrene (PHE) and pyrene (PYR) in a soil were differentiated using a humic separation procedure after multi-concentration sorption experiments. It was found that the amount of solutes in FA/HA did not change significantly after 48 h, while that in HM increased continuously and slowly up to the end of the experimental period (720 h), indicating that HM was the main region for slow sorption. Based on the fitting results using Freundlich equation, it was found that nonlinearity of both solutes was greater in HM than in FA/HA, consistent with the sorption characteristics of individually extracted HA and HM in a separate experiment. The observed nonlinearity of the solute distribution was confirmed by using three other soil samples with organic carbon contents ranging from 0.7 to 7.9%. Distribution dynamics of PHE and PYR among various fractions were also discussed.

Adsorption↗
PubMed2005

Multiple cotunneling in large quantum dot arrays.

We investigate the effects of inelastic cotunneling on the electronic transport properties of gold nanoparticle multilayers and thick films at low applied bias, inside the Coulomb-blockade regime. We find that the zero-bias conductance, g(0)(T), in all systems exhibits Efros-Shklovskii-type variable range hopping transport. The resulting typical hopping distance, corresponding to the number of tunnel junctions participating in cotunneling events, is shown to be directly related to the power-law exponent in the measured current-voltage characteristics. We discuss the implications of these findings in light of models on cotunneling and hopping transport in mesoscopic, granular conductors.

Journal Article↗
PubMed2001

[Long-term efficacy of vaccination against hepatitis B in newborns: 13 years' follow-up].

OBJECTIVE: To evaluate long-term efficacy of hepatitis B vaccination in newborns. METHODS: In the past 13 years we followed up the children who had been immunized with hepatitis B vaccine at birth in 1986 every other year. At each follow-up visit, every child was tested for HBsAg, anti-HBs and anti-HBc. RESULTS: HBsAg positive rate of these birth cohort was low (range between 0.46% and 0.98%) during 13 years' follow-up. Long-term efficacy of the vaccination in preventing HBsAg carriage was confirmed. CONCLUSIONS: Thirteen years later no booster was after needed.

Female↗
PubMed2000

[Clinical significance of P-glycoprotein and CD34 expression of acute leukemia].

The expression of P-glycoprotein(P-170) and CD34 was detected in the bone marrow mononuclear cells of 30 patients with acute leukemia by immunocytochemical technique using JSB-1 and Tük 3 monoclonal antibody. The results were that expression of P-170 and CD34 had no significant difference between acute nonlymphoblastic leukemia and acute lymphoblastic leukemia(P > 0.05). The clinical therapeutic effect was poor in P-170 or CD34 positive patients and had significant difference compared with those negative patients(P < 0.05). Judgments of therapeutic effect for acute leukemia can be improved by detecting the expression of P-170 and CD34 simultaneously.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Cisapride provides symptomatic relief in functional dyspepsia associated with gastric myoelectrical abnormality.

OBJECTIVE: We evaluated the effects of cisapride (10 mg t.d.s. and 20 mg b.d.) on gastrointestinal symptoms and gastric myoelectrical activity in patients with functional dyspepsia. Myoelectrical activity was measured by electrogastrography. METHODS: Patients with functional dyspepsia, defined as discomfort in the epigastrium, a negative endoscopy, and clinical symptoms of dyspepsia, were enrolled. A total of 38 patients participated in the study (23 female; 15 male; 24-72 years of age). Screening electrogastrography identified those with a normal electrogastrogram (14 subjects) and those with an abnormal electrogastrogram (24 patients). Patients were randomly assigned to 2 weeks of placebo or 2 weeks of cisapride (10 mg t.d.s.); both groups then received 2 weeks of cisapride (20 mg b.d.). Electrogastrograms were repeated at the end of each 2-week treatment period. RESULTS: Cisapride 10 mg t.d.s. significantly improved symptoms in all patients. An additional 2 weeks of treatment with cisapride 20 mg b.d. led to continued improvement in symptoms in all patients, with significant improvement in the group with abnormal baseline electrogastrograms. Cisapride significantly improved postprandial bloating and discomfort in patients with abnormal baseline electrogastrograms. Cisapride also significantly improved postprandial gastric myoelectrical activity as measured by electrogastrography in patients with abnormal baseline electrogastrograms. CONCLUSION: Cisapride provides symptomatic relief and improves gastric myoelectrical abnormalities in patients with functional dyspepsia.

Adult↗
PubMed1997

Naloxone microinjected into the arcuate nucleus has differential effects on ventilation in male and female rats.

The arcuate nucleus of the hypothalamus, a highly sexually dimorphic brain region, has been called the bed nucleus for endogenous opioids. The potential contribution of opioids in this nucleus to modulate control of ventilation in male and female rats has not been investigated. The purpose of the present study is to determine the effect of microinjecting naloxone, an opioid receptor antagonist, into the arcuate nucleus of awake male and female rats on ventilation, oxygen consumption, heart rate, and blood pressure. Results of this study demonstrate that naloxone at doses of 1.5 and 3.0 nmol relative to vehicle caused a depression of ventilation due to a decrease of both frequency of breathing and tidal volume in male rats and a decreased response to a hypercapnic challenge in female rats. Although there were gender differences noted in oxygen consumption, heart rate, blood pressure, and ventilatory response to a hypoxic challenge, only oxygen consumption was significantly affected by naloxone. Potential mechanisms whereby naloxone may act to depressing ventilation are discussed.

Animals↗
PubMed1995

Effects of deferoxamine and a diet deficient in vitamin E on isoelectric electroencephalographic responses associated with ischemia by the four vessel occlusion method.

This study reports the effects of subchronic administration of the iron chelator deferoxamine (4.2 mg/day by osmotic minipump for 6 days) and a diet deficient in Vitamin E (15% RDA for 60 days) on the isoelectric electroencephalographic responses associated with 15 minutes of global transient cerebral ischemia in rats. Brain levels of thiobarbiturate-reacting substance (TBARS), a measure of lipid peroxidation, were lower in deferoxamine-treated animals and higher in Vitamin E deficit animals suggesting the treatments altered free radical activity at the time of ischemia. During ischemia, all test animals were observed to lose the righting reflex and enter a quiescent state. Fifty percent of the animals in two control groups (N = 15 per group) demonstrated an isoelectric electroencephalographic pattern (defined as 10% or less of pre-ischemia total EEG power) with a mean onset of 5.44 minutes. One third of the animals treated with deferoxamine (N = 15) experienced an isoelectric encephalogram with a mean onset of 8.6 minutes and 73% of the Vitamin E-deficient group (N = 15) experienced an isoelectric EEG with a mean onset of 3.43 minutes. Following reperfusion, EEG patterns returned to power levels within 20% of pre-ischemia levels in all animals. Control animals obtained this EEG power level within 1.34 minutes, deferoxamine-treated animals within 1.25 minutes and animals provided a diet deficient in Vitamin E within 5.03 minutes. Compared to mean total EEG power prior to the onset of ischemia, mean total EEG power five days after reperfusion was reduced 14% in the control groups and 59% in the Vitamin E-deficient group and increased 123% in the deferoxamine group. Results are discussed in relation to the possible involvement of free radicals in the ischemic and postischemic process.

Animals↗
PubMed1991

A survey of epidemiology of Gnathostoma hispidum and experimental studies of its larvae in animals.

The present study is concerned with a survey of the epidemiology and infectivity of Gnathostoma hispidum larvae in animals. A total or 3,478 pigs were examined in Hongze-Lake, Jiangsu; Po-Lake, Anhui; and Jiujiang, in Jiangxi Province. The infection rate of G. hispidum in pigs was 14.9%. The prevalence in pigs in the lake districts (26.4%) was considerably higher than in the mountainous districts (5.1%). The results of field surveys and experimental studies revealed that in China, 38 animal species served as the first and the second intermediate hosts and paratenic hosts of G. hispidum. Among them, 23 species (6 cyclops, 13 fish, 2 frogs and one each of snake and bird) were similar to the hosts of G. spinigerum. Carnivorous fish, frogs and rodents are an important infection source for gnathostomiasis. Experiments demonstrated that Macaca mulatta was successfully infected with the early 3rd-stage larvae from cyclops or the advanced 3rd-stage larvae from fish. The domestic cat and white rat were experimentally infected by skin penetration by advanced 3rd-stage larvae of G. hispidum obtained from fish; the results of the test were all positive. The survey of epidemiology and biology of G. hispidum and G. spinigerum were quite similar, so the authors consider that humans may be infected by G. hispidum.

Animals↗
PubMed1990

Assessment of intradermal test in longitudinal surveillance of bancroftian filariasis.

Longitudinal surveillance was carried out consecutively during 1982-1987 in two pilot villages where bancroftian filariasis was prevalent in different severity before 1982. Intradermal test (IT) with filaria polypeptide (FPT) antigen prepared from Dirofilaria immitis was made. It was shown that the level of immediate hypersensitivity reaction to the antigen in population as shown by IT appeared to be directly proportional to both the prevalence of the disease and the infection rate of mosquitoes harbouring larval filariae before mass and selective treatment with diethylcarbamazine. Time for negative conversion of IT after chemotherapy was significantly longer in previous microfilaraemic patients than that in amicrofilaraemic cases. The selected three criteria of IT used in filariasis surveillance, namely, the positive rate, frequency of strong reaction and positive conversion rate, were diminished gradually after chemotherapy year by year, so that the three criteria were demonstrated to be useful for longitudinal surveillance of lymphatic filariasis.

Adolescent↗
PubMed1990

[A clinico-pathologic study of 31 cases of parathyroid hyperplasia and tumours].

31 cases of primary hyperplasia and neoplasms of the parathyroid gland are reported. Among them, 23 cases were parathyroid adenoma, 6 cases parathyroid hyperplasia, one case adenoma associated with hyperplasia, and one case of parathyroid adenocarcinoma. Follow-up study demonstrated that prognosis in the adenoma group is better than that in the hyperplasia group, and one carcinoma patient died from metastasis. Regarding differential diagnosis, adenoma is usually single, with frequent presence of oppressed parathyroid tissue next to the tumor capsule; and cell atypical hyperplasia is often seen microscopically, which is usually multiple in sites, and some residual adipose tissue can be found under the microscope. Clinically, both groups manifested hypercalcemia and hypophosphatemia, especially in those cases with chief cell hyperplasia. Capsule infiltration and vascular embolism are emphasized as the differential features between benign and malignant parathyroid tumours.

Adenocarcinoma↗