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Biomedical subjects

H Yuan

Publications and source records attributed to H Yuan.

At least 55 records · Page 3Linked to original sources
PubMed2001

[Cytomegalovirus infection associated with plasma endothelin and P-selectin in patients with essential hypertension].

BACKGROUND: To investigate the relationship between human cytomegalovirus (HCMV) infection and plasma endothelin and P-selectin in patients with essential hypertension. METHODS: Blood samples of 98 patients with essential hypertension were collected for HCMV IgM and IgG antibodies, plasma endothelin and plasma P-selectin by chemiluminescence technique, radio-immunoassay and ELISA. RESULTS: The rates of positive HCMV IgM antibodies and positive rates for both HCMV IgM and IgG antibodies were 56.12% and 54.08%, respectively, which were higher than that of the control group (P=0.05). The level of plasma endothelin and P-selectin in patients with positive HCMV IgM antibodies was 95.53 +/- 5.06 ng/ml and 42.50 +/- 3.28 ng/ml, respectively, which were higher than that in patients with negative HCMV IgM antibodies (71.60 +/- 4.34 ng/ml and 27.41 +/- 5.28 ng/ml) and that of the control group (48.77 +/- 5.96 ng/ml and 19.80 +/- 4.62 ng/ml). CONCLUSIONS: These results suggest that HCMV active infection may aggravate vascular endothelium lesi on in patients with essential hypertension and contribute to the increase of endothelin and P-selectin.

Adult↗
PubMed2001

Clinical trials in Alzheimer's disease. Calculating Alzheimer's Disease Assessment Scale-cognitive subsection with the data from the consortium to establish a registry for Alzheimer's disease.

The database of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) is a seminal work in the field of cognitive dysfunction and Alzheimer's disease. This 24-center study of 1,094 patients with Alzheimer's disease who received no treatment for their cognitive dysfunction and 463 normal control subjects is rich in neurobehavioral data and contains extensive imaging and neuropathologic findings. However, the Alzheimer's Disease Assessment Scale (ADAS) was not administered as part of the CERAD study, which limits the study's applicability to modern drug trials, in which the ADAS-cognitive subsection (ADAS-cog) is a popular end point. The purpose of this investigation was to develop a derived ADAS-cog score from the neurobehavioral data obtained from subjects during their evaluation in the CERAD study. Two calculated ADAS-cog scores were developed. The first was based on clinically mapping the items on the ADAS-cog to assessments that were performed in the CERAD study. The second was based on rescaling the Mini-Mental Status Exam (MMSE), using published results correlating the ADAS-cog to the MMSE. Standard characteristics of both calculated ADAS-cog scores were calculated and compared with each other and with the literature. Both calculated ADAS-cog scores performed comparably to published characteristics of the ADAS-cog. The clinically based calculated ADAS-cog outperformed the rescaled MMSE. Using the CERAD database, it is now possible to model the progression of an untreated (placebo) population of patients with Alzheimer's disease and correlate it to a study using ADAS-cog.

Aged↗
PubMed2001

[Study on some metal elements levels and the T lymphocyte subset of the peripheral lymphocytes in patients with nasopharyngeal carcinomas].

OBJECTIVE: To study some metal elements levels and T lymphocyte subset of the peripheral lymphocytes in patients with nasopharyngeal. METHOD: Metal elements in the patients with nasopharyngeal and normal control were detected by the Atomic Absorption Spectrometer (Flame SHIMATZV.JAPAN). T lymphocyte subset were detected by the flow cytometry (FCM). RESULT: The level of copper was significantly higher and the level of zinc was significantly lower in patients with nasopharyngeal carcinomas than those in normal control group (P < 0.01 and < 0.05 respectively). The number of CD3/CD4 cell in the patients group were less than those in normal group(P < 0.01). CONCLUSION: The results of correlative analysis showed that there was a significant correlationship between the number of CD4 cells and levels of copper in peripheral lymphocytes of the patients group.

Adult↗
PubMed2001

[Improved retrosigmoid approach operation in the treatment of trigeminal neuralgia].

OBJECTIVE: To explore the surgical method which can raise the treatment effect and reduce the complication occurrence of cerebellopontine angle (CPA) operation by retrosigmoid approach. METHOD: Have improved the retrosigmoid approach in the skin incision, the hole position of bone, the intracranial operation skills and the duramatral suture, etc. By the improved retrosigmoid approach, we used partial sensory rhizotomy (PSR) to cure 54 cases with trigeminal neuralgia (TN). RESULT: 52 cases got satisfactory treatment effect and no complication appeared. In the other 2 cases, the trigeminal nerve was not found in CPA. CONCLUSION: The CPA operation by retrosigmoid approach is dangerous relatively, it usually can cause some serious complication. But improved retrosigmoid approach can expose CPA sufficiently and is convenient to operate. On the other hand, it can decrease intracranial unexpected hemorrhage and complication occurrence.

Adult↗
PubMed2001

[Study of quantitative calibration model suitability in near-infrared spectroscopy analysis].

Near-infrared spectroscopy is a fast, high efficiency and low cost analytical technique, that depended on analytical models which are built through near-infrared spectra, the primary method results of calibration set and chemometrics methods. The reliability of analytical results mostly depends on the suitability of analytical model to unknown samples. To judge the suitability of analytical model, a new method is presented that combine principle factor analysis (PCA) and Mahalanobis distance. It is different with traditional method, that the Mahalanobis distance is calculated through PCA factor scores. It can avoid the wavelengths selection problem in traditional method of spectral Mahalanobis distance. Through the determination of cetane number of diesel fuel, some factors that affect model suitability judgement are discussed.

Calibration↗
PubMed2000

Four-year follow-up results of lumbar spine arthrodesis using the Bagby and Kuslich lumbar fusion cage.

STUDY DESIGN: This was a prospective multicenter clinical trial of a lumbar interbody fusion cage with a minimum of 4 years' follow-up. OBJECTIVES: To determine whether the early positive clinical results in fusions with lumbar cages, such as the Bagby and Kuslich (BAK) cage, are maintained beyond 2 years. SUMMARY OF BACKGROUND DATA: Threaded cages have been used increasingly for the treatment of symptomatic degenerative intervertebral disc disease. Concerns about the long-term clinical outcomes of this procedure have been posed, particularly regarding bony fusion viability, revision rates, potential adjacent level disease, and late complications. METHODS: The study cohort was a 196-patient subset from a prospective investigational device exemption. In addition to early postoperative examinations, these patients were examined biannually with a minimum of 4 years' follow-up. Patient outcome was assessed by a 6-point scale that evaluated pain relief, and functional improvement was determined by changes in activities of daily living. Fusion rates and return to work were determined. Complications and secondary operations were reported and categorized as non-device related or device related. RESULTS: The patient cohort with 4-year follow-up represented 25.6% of the original study population eligible at that time. Overall, the largest percentage of pain relief and functional improvements occurred by 3 months, and these improvements were maintained at each follow-up. Overall fusion rate was 91.7% and 95. 1% at 2 and 4 years, respectively. In this cohort, 39.5% of patients were working or were able to work within 3 months of surgery. After 4 years, 62.7% of patients were gainfully employed or able to work. The late-occurring complication rate in this cohort was 13.8% (27/196). Complications necessitating a second operation occurred in 8.7% (17/196), whereas reoperations that were deemed device related were performed in 3.1% (6/196). CONCLUSIONS: This study indicates that the early positive benefits of interbody fusion cage procedures are maintained through 4 years with acceptably low morbidity.

Cohort Studies↗
PubMed2000

Regulation of the activity of caspases by L-carnitine and palmitoylcarnitine.

L-Carnitine facilitates the transport of fatty acids into the mitochondrial matrix where they are used for energy production. Recent studies have shown that L-carnitine is capable of protecting the heart against ischemia/reperfusion injury and has beneficial effects against Alzheimer's disease and AIDS. The mechanism of action, however, is not yet understood. In the present study, we found that in Jurkat cells, L-carnitine inhibited apoptosis induced by Fas ligation. In addition, 5 mM carnitine potently inhibited the activity of recombinant caspases 3, 7 and 8, whereas its long-chain fatty acid derivative palmitoylcarnitine stimulated the activity of all the caspases. Palmitoylcarnitine reversed the inhibition mediated by carnitine. Levels of carnitine and palmitoyl-CoA decreased significantly during Fas-mediated apoptosis, while palmitoylcarnitine formation increased. These alterations may be due to inactivation of beta-oxidation or to an increase in the activity of the enzyme that converts carnitine to palmitoylcarnitine, carnitine palmitoyltransferase I (CPT I). In support of the latter possibility, fibroblasts deficient in CPT I activity were relatively resistant to staurosporine-induced apoptosis. These observations suggest that caspase activity may be regulated in part by the balance of carnitine and palmitoylcarnitine.

Acylation↗
PubMed2000

Synthesis and preliminary biological evaluations of CC-1065 analogues: effects of different linkers and terminal amides on biological activity.

CC-1065 analogues possessing a biologically active CBI functional group and amide-substituted indole and benzofuran were synthesized. The IC(50) values of compounds 26, bearing two indoles, and 25, bearing only one indole, are 0.4 and 3 nM, respectively, against U937 leukemia cells in vitro. The IC(50) values of compounds 28, bearing a butyramino group, and 27, bearing an acetamino group, are 0.008 and 0.4 nM, respectively, against U937 leukemia cells in vitro. Compound 29, bearing a double-bond linker, is about 4-fold more potent than 25, bearing no double-bond linker. Compound 26 is highly potent against all cell lines tested in the NCI in vitro screening with IC(50) values in the 0.1-5 nM range for most cell lines. Compounds 26 and 30 are highly active against L1210 leukemia in mice. Compound 26 is also active against B16BL6 melanoma in mice. Most importantly, 26 and 30 are not myelosuppressive at therapeutically effective doses. The mechanism of tumor cell death is through induction of apoptosis, and is accompanied by DNA fragmentation.

Animals↗
PubMed2000

Structural diversity based on cyclopropane scaffolds

[structure: see text] A practical and efficient route for the stereoselective conversion of easily accessible homoallylic alcohols to diastereomerically pure cis- and trans-disubstituted and 1,2,3-trisubstituted cyclopropanes has been developed. The diversity of structures that can be prepared and the simplicity of the overall sequence make this route ideal for extension to solid-phase synthesis techniques and ultimately combinatorial library generation.

Journal Article↗
PubMed2000

Proteasome inhibition in neuronal cells induces a proinflammatory response manifested by upregulation of cyclooxygenase-2, its accumulation as ubiquitin conjugates, and production of the prostaglandin PGE(2).

Inclusions containing ubiquitin-protein aggregates appear in neurons of patients with neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. The relationship between inclusion production and cell viability is not understood. To address this issue, we investigated the response of an established mouse neuronal cell line and of embryonic rat mesencephalic cultures to inhibition of the ubiquitin/proteasome pathway. Two proteasome inhibitors, a peptidyl aldehyde and an epoxy ketone, which cause accumulation of ubiquitinated proteins, were found to enhance expression of stress-inducible genes, including HSP70i and the polyubiquitin genes UbB and UbC. Under these conditions, mRNA and protein levels of the inducible form of cyclooxygenase (COX-2) were upregulated together with its product, PGE(2), a proinflammatory prostaglandin. Proteasomal inhibition also led to stabilization of COX-2 as ubiquitin conjugates, suggesting that the ubiquitin/proteasome pathway contributes to the regulation of COX-2 protein levels. Treatment with antioxidants known to inhibit NFkappaB and AP-1 transcriptional activation failed to abrogate COX-2 upregulation. Instead, these inhibitors exacerbated the stress response by potentiating HSP70i levels while eliciting a decrease in PGE(2) production. These findings suggest that the accumulation of ubiquitinated proteins resulting from proteasome inhibition in neuronal cells is associated with a proinflammatory response that may be an important contributor to neurodegeneration.

Animals↗
PubMed2000

Preparation and characterization of calixarene-coated capillaries for capillary electrophoresis.

Preparation and characterization of calixarene-coated capillaries for capillary electrophoresis (CE) were exemplified with p-allylcalix[4]arene (pACX4) which was immobilized to the fused silica surface using gamma-methacryloxypropyl-trimethoxysilane (gamma-MAPS) as linking agent. Successful gamma-ACX4 coating was suggested by the greatly decreased electroosmotic flow (EOF), due to the introduction of phenolic hydroxyl groups on the inner surface of the capillaries. A slight slope of EOF versus pH at pH <8 would help make the separation reproducible. The coated columns also featured a low ultraviolet (UV) absorption background and long lifetime (> 6 months at 4<pH<9). Moreover, their special selectivity on phenolic compounds indicated a certain extent of selective interactions between solutes and the calixarene coating, which effected separations partially based on an electrochromatographic mechanism.

Calixarenes↗
PubMed2000

Tissue responses of calcium phosphate cement: a study in dogs.

The in vivo properties of a new kind of calcium phosphate cement were investigated in this study. Calcium phosphate cement was implanted as paste into femoral bone and dorsal muscle of dogs for 3 and 6 months, and as prehardened form into thigh muscles of dogs for 1, 2 and 6 months. Histology was performed on thin un-decalcified sections. No foreign body reaction, no inflammation and no necrosis were found both in bony site and in muscles. There was no connective tissue layer between the cement and bone when cement paste was implanted in the bone. A creeping substitution of cement by bone, in which osteoclast-like cells resorbed the cement as if the cement is a part of bone and new bone was formed directly on the resorption line of calcium phosphate cement, was found. Bone formation was found histomorphologically in pores and deep rugged surface of cement samples (both paste and prehardened form) implanted in muscles of dogs. The induced bone was also identified with backscattered scanning electron microscopy (BSE) and by energy-dispersive X-ray micro-analysis (EDX). The results suggest that the calcium phosphate cement used in this study is biocompatible, resorbable in a manner of creeping substitution, osteoconductive and osteoinductive. It seems that an ideal bone substitute can be developed by using this type of calcium phosphate cement.

Absorbable Implants↗
PubMed2000

The determination of a chlorinated benzofuran pharmaceutical intermediate by HPLC-MS with on-line derivatization.

An HPLC-MS method for the analysis of 2-chloromethylbenzofuran, a pharmaceutical intermediate alkylating reagent employed in the preparation of a second generation HIV protease inhibitor, N-(2(R)-hydroxy-l(S)-indanyl)-2(R)-phenylmethyl-4(S)-hydroxy-5-(1-(4-(2- benzo[b]furanylmethyl)-2(S)-N'-9-t-butyl-carboxamido)-pipera zinyl))-pentaneamide, is described. Preliminary analysis of the protease inhibitor by HPLC-MS indicated that the quality of the drug substance was influenced by the composition of the chloromethylbenzofuran. Direct analysis of the chloromethylbenzofuran by LC-MS using atmospheric pressure ionization was unsuccessful, necessitating an alternative approach. The method described incorporated post-column derivatization of the chloromethyl benzofuran using a modification of the drug substance process chemistry yielding a derivative amenable to MS analysis using atmospheric pressure chemical ionization (APCI). This allowed measurement of an impurity in the chloromethylbenzofuran which was incorporated into the protease inhibitor.

Benzofurans↗
PubMed2000

The 1992-1999 World Bank Schistosomiasis Research Initiative in China: outcome and perspectives.

Ongoing efforts over the last 50 years, aiming at the elimination of schistosomiasis in the People's Republic of China, have been spectaculary successful in reducing the prevalence and intensity of the infection. The endemic areas have been reduced to core regions with particular problems such as the middle and lower reaches of the Changjiang River (Yangtze), the land adjacent to the lakes of central China and certain mountainous areas in Sichuan and Yunnan. An effort to eradicate schistosomiasis as a public health problem in these areas, by means of mass chemotherapy in regions of high prevalence and selective chemotherapy in others, provided good results initially but a lasting effect proved unattainable with chemotherapy alone. A small part of the funds available for this effort were used for research and training. Overseen by a Joint Research Management Committee (JRMC), research training was intensified resulting in improved applications and a better quality of the scientific level of the research finally carried out. Several new control tools were produced which may improve future control approaches, which might achieve a more than temporary relief. In evaluating the contributions made, it was found that the great environmental variations between the eight provinces where control activities were implemented was the main reason why general use of chemotherapy only could not be entirely successful. The inclusion of a research component proved beneficial both for the short- and long-term control and the JRMC proved useful in exposing that sustained progress cannot be achieved without back-up by other approaches, e.g. snail control. Suggested future activities include strengthening of intersectoral and industrial collaboration but finding financial support for continuing the JRMC initiative in some form. It is crucial to consolidate progress made.

Animals↗
PubMed2000

On molecular polarizability: 3. Relationship to the ionization potential of haloalkanes, amines, alcohols, and ethers

The relationship between the ionization potential and the parameters molecular electronegativity and molecular polarizability for haloalkanes, amines, alcohols, and ethers was investigated. There is no good linear correlation between the ionization potential Ip and molecular electronegativity chi(eq) alone for these compounds. Ip can be modeled well with three parameters: chi(eq), polarizability effect index (PEI) of an alkyl group, and atomic polarizability (P). Further, a single expression for predicting the Ip values of aldehydes, esters, nitriles, and carboxylic acids was developed: Ip(Rz)(eV) = Ip(MeZ) + 1.4544delta chi(eq) - 1.6435delta sigmaPEI(Ri). Here Ip(MeZ) is the experimental ionization potential of monosubstituted methane MeZ. Delta chi(eq) and delta sigmaPEI(Ri) are the difference in the molecular electronegativity and the difference in the polarizability effect index of alkyl groups attached to the functional group Z between molecules MeZ and RZ, respectively.

Journal Article↗
PubMed2000

Effects of collagenase and elastase on the mechanical properties of lung tissue strips.

The dynamic stiffness (H), damping coefficient (G), and harmonic distortion (k(d)) characterizing tissue nonlinearity of lung parenchymal strips from guinea pigs were assessed before and after treatment with elastase or collagenase between 0.1 and 3.74 Hz. After digestion, data were obtained both at the same mean length and at the same mean force of the strip as before digestion. At the same mean length, G and H decreased by approximately 33% after elastase and by approximately 47% after collagenase treatment. At the same mean force, G and H increased by approximately 7% after elastase and by approximately 25% after collagenase treatment. The k(d) increased more after collagenase (40%) than after elastase (20%) treatment. These findings suggest that, after digestion, the fraction of intact fibers decreases, which, at the same mean length, leads to a decrease in moduli. At the same mean force, collagen fibers operate at a higher portion of their stress-strain curve, which results in an increase in moduli. Also, G and H were coupled so that hysteresivity (G/H) did not change after treatments. However, k(d) was decoupled from elasticity and was sensitive to stretching of collagen, which may be of value in detecting structural alterations in the connective tissue of the lung.

Airway Resistance↗
PubMed2000

Morphometric evaluation of the human cervical motoneurons.

Morphometric analysis of the human cervical large motoneurons in the anterior horn was performed in 7 male cadavers with the help of an image-analyzer and the use of a new tissue preparation method which minimizes shrinkage. This method makes it possible to precisely evaluate the size of cervical motoneurons at each level. Our study revealed a difference in number, average area and total area of the motoneurons between C1-C3 and C4-C7 levels. This results can be of importance in setting standard values for the understanding of morphological and functional correlations.

Adult↗