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Biomedical subjects

Y Fu

Publications and source records attributed to Y Fu.

297 records · Page 17Linked to original sources

3-Nitropropionic acid produces indirect excitotoxic damage to rat striatum.

The mechanism of striatal damage induced by 3-nitropropionic acid (3-NPA) was studied in rats by neuropathological and neurochemical methods. Neuronal shrinkage with astrogliosis was observed in striatum after local injection of 0.5-5 mumol 3-NPA. Decortications involving dorsal and lateral aspects of frontal cortex or both frontal and parietal cortices significantly decreased the severity of striatal injuries induced by 3-NPA. This result suggests that corticostriatal projections play an important role in the development of striatal damage. No significant increase of glutamate and aspartate in striatal dialysates was observed, which indicated that 3-NPA may affect the postsynaptical sites and make the striatal neurons more vulnerable to endogenous levels of glutamate. Both of these findings suggested that 3-NPA produces indirect excitotoxic lesion to striatum. An increase of dopamine found in striatal dialysates may also be related to the occurrence of striatal damage.

Animals↗

Consistent striatal damage in rats induced by 3-nitropropionic acid and cultures of arthrinium fungus.

Arthrinium fungi were cultivated from the samples of mildewed sugarcane which caused acute encephalopathy and delayed dystonia in children. The Arthrinium cultures (AC) contained 5 mg/ml 3-nitropropionic acid (3-NPA) after being inactivated and concentrated. A neuropathological study was carried out in rats intoxicated with 3-NPA and AC, respectively. Consistent bilateral striatal necrosis was found in rats with both poisonings, and the severity was well correlated with persistent recumbency which was a clinical indicator of the development of morphological brain lesions. A reproducible animal model of striatal damage has been produced in rats by IP injections of 10 mg/kg 3-NPA, 6 times a day, with an interval of 1.5 h for 3-5 days. The clinical and neuropathological manifestations in rats dosed with AC were nearly the same as those dosed with 3-NPA. The striatal lesions induced by 3-NPA and AC in poisoned rats were in accordance with the bilateral lenticular hypodensity found by CT scanning in patients of mildewed sugarcane poisoning with delayed dystonia. This neuropathological evidence supports previous epidemiological and mycological findings which indicate that 3-NPA is the possible pathogen of acute mildewed sugarcane poisoning.

Animals↗

Cystic echinococcosis in semi-nomadic pastoral communities in north-west China.

In order to determine the prevalence of human cystic echinococcosis (CE) in semi-nomadic traditional pastoralist groups in north-west China, 2 large community studies were undertaken in Altai and Tacheng Prefectures in 1990/91 and 1995/96, respectively. The Kekergash community (Altai) comprised mainly ethnic Kazakhs, whereas the Narenhebuke community (Tacheng) comprised mainly Mongolians. Populations were screened for CE by abdominal ultrasound scan (US) and serological tests. The total prevalence of confirmed human CE was higher in Narenhebuke (2.7%, 49/1844) than in Kekergash (0.9%, 17/1861; P < 0.01). Within each community there was no significant difference of CE prevalence between the Kazakh and Mongolian groups, although Han Chinese exhibited twice the rate of CE (4.9%) in Narenhebuke compared to the dominant Mongolian population. For each community, human CE prevalence increased with age and there was a greater risk associated with the practice of home slaughter of livestock. Dogs were screened for Echinococcus granulosus infection and re-infection levels using a highly specific coproantigen test. The proportion of dogs with positive coproantigen tests was significantly higher in Narenhebuke (36.0%, 50/139) compared to Kekergash (17.8%, 16/90). In Narenhebuke the re-infection levels of dogs, as determined by coproantigen positivity, were higher in the winter quarters (49.4%, 39/79) compared to the summer quarters (18.3%, 11/60; P < 0.01). Furthermore, coproantigen re-test positivity was 25% at 3 months and 29.2% at 7 months. Highest dog coproantigen positivity was obtained over the winter period.

Adolescent↗

MR imaging of dural AV fistulas at the cavernous sinus.

The magnetic resonance appearance of dural arteriovenous fistulas (AVFs) at the cavernous sinus (CS) was studied in six angiographically verified cases. Magnetic resonance clearly demonstrated shunted blood as an area of signal void both in the CS and in the superior ophthalmic vein. The relationship between shunted blood, internal carotid artery, and extraocular nerves, as well as proptosis, enlargement of the extraocular muscles, and bulging of the lateral wall of the CS were also depicted in the images. Normal venous flow in the involved CS was shown as a low signal area that enhanced after gadolinium administration. Magnetic resonance is useful for screening and follow-up examinations of dural AVFs at the CS. It is essentially a noninvasive procedure that may be repeated and obviates the need for follow-up angiography. However, it should be noted that a signal void in the CS sometimes represents normal venous flow. A definite diagnosis should rely on angiography, which is essential for therapeutic planning.

Aged↗

InAs quantum dots capped by GaAs, In0.4Ga0.6As dots, and In0.2Ga0.8As well.

We have fabricated and characterized three types of InAs quantum dots (QDs) with different InxGa1-xAs capping layers. Post-growth atomic force microscopy measurements show that the In0.2Ga0.8As/InAs structure has a smooth surface (dot-in-well structure), whereas the In0.4Ga0.6As/InAs structure revealed large QDs with a density similar to that underneath InAs QDs on GaAs (dot-in-dot). With increasing In mole fraction of the capping layer and increasing In0.4Ga0.6As thickness, the energy position of the room-temperature photoluminescence (PL) peak is red-shifted. The quantum dot-in-dot structure emits stronger room-temperature PL than does the quantum dot-in-well structure. With a spatially distributed strain in the InAs quantum dot, we have solved the three-dimensional Schrödinger equation by the Green's function theory for the eigenvalues and eigen wave functions. It is concluded that the ground state increases its wave function penetration into the low-barrier InxGa1-xAs capping layer so that its energy position is red-shifted. The reduced PL peak intensity of the dot-in-well (compared with GaAs covered dots) is due to the reduced overlapping between the ground state and the extended states above the GaAs barrier. The overlapping reduction in the dot-in-dot is over compensated for by the reduced relaxation energy (full width at half-maximum), indicating the importance of the sample quality in determining the PL intensity.

Arsenicals↗

A protamine filter for extracorporeal heparin removal. Development, testing, blood compatibility evaluation, and future direction.

The authors previously developed a filter device containing immobilized protamine (termed "protamine filter") that could be used to remove heparin during extracorporeal perfusion. In vivo studies involving dogs showed that the protamine filter removed more than 50% of heparin from the animals' blood circuit in less than 20 min. In addition, the use of the protamine filter did not elicit statistically significant protamine induced hemodynamic and thrombocytopenic responses. Biocompatibility of the protamine filter was also evaluated, with the focus on its effect on the coagulation cascade, the complement system, and the blood antithrombin III levels. Results showed that heparin adsorbed to the protamine coated surface retained 20% of its original activated partial thromboplastin time activity, rendering the coated surface antithrombotic. Activation of the coagulation system by the protamine coated membrane and the untreated cellulose membrane, as measured by the elevation of prothrombin fragment F1 + 2 levels, was statistically identical. The CH50 hemolytic assay showed that the protamine coated membrane produced a reduction of 1.2 +/- 0.8% of the total complement levels, as compared to 9.4 +/- 1.6% by the untreated membrane. In addition, the change in C3a des Arginine levels after 30 min of circulation was 1.5 +/- 0.2 mg/ml by the protamine filter, as compared to 2.1 +/- 0.1 mg/ml by the untreated membrane. Unlike native heparin that would bind with antithrombin, heparin adsorbed on the protamine coated surface was devoid of such activity, and produced no depletion of circulating antithrombin. Because of the limited capacity of the protamine filter, the future system is envisioned to consist of two filters; while one filter is removing heparin the other will be regenerated. With a recently developed heparin sensor, it should be possible to design a sensor directed, biofeedback, two filter heparin removal system.

Adsorption↗

Local multicystic encephalopathy: case report.

A case of local multicystic encephalopathy is presented. CT scan showed a low-density area with a string-like structure of iso-density in the left frontal lobe. Angiogram demonstrated no abnormality. Magnetic resonance imaging (MRI) demonstrated multiple cystic lesions, and we diagnosed the case as local multicystic encephalopathy. This disease generally occurs diffusely, and local occurrence is very rare. MRI was very useful for diagnosis and delineating the details.

Adult↗