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Y P Huang

Publications and source records attributed to Y P Huang.

At least 19 recordsLinked to original sources
PubMed2005

Ultrasonic measurement of depth-dependent transient behaviors of articular cartilage under compression.

We previously reported an ultrasound method for measuring the depth-dependent equilibrium mechanical properties of articular cartilage using quasi-static compression. The objective of this paper was to introduce our recent development for nondestructively measuring the transient depth-dependent strains of full-thickness articular cartilage specimens prepared from bovine patellae. A 50 MHz focused ultrasound transducer was used to collect ultrasound echoes from articular cartilage specimens (n=8) and sponge phantoms with open pores (n=10) during tests of compression and subsequent stress-relaxation. The transient displacements of the tissues at different depths along the compression direction were calculated from the ultrasound echoes using a cross-correlation tracking technique. An LVDT sensor and a load cell were used to measure the overall deformation of the tissue and the applied force, respectively. Results showed that the tissues inside the cartilage layer continued to move during the stress-relaxation phase after the compression was completed. In the equilibrium state, the displacements of the cartilage tissues at the depths of 1/4, 1/2, and 3/4 of the full-thickness reduced by 51%+/-22%, 54%+/-17%, and 50+/-17%, respectively, in comparison with its peak value. However, no similar phenomenon was observed in the sponge phantoms. Our preliminary results demonstrated that this ultrasound method may provide a potential tool for the nondestructive measurement of the transient depth-dependent processes involved in biological and bioengineered soft tissues as well as soft biomaterials under dynamic loading.

Animals↗
PubMed2004

A heat inducible tyrosinase with distinct properties from Bacillus thuringiensis.

AIMS: The objective of this work was to purify the tyrosinase from Bacillusthuringiensis subsp. kurstaki (Bt) (CCTCC AB 90010) and study its enzymatic properties. METHODS AND RESULTS: A 'one-step' purification method was used in this work, which was an easy, high-yield purification method. Tyrosinase activity of this purity was measured under different conditions to study its kinetic characterizations. The optimum pH and thermal stability of this enzyme were also determined. The results revealed that the tyrosinase from Bt has distinct properties compared with those from other sources. CONCLUSIONS: A heat-inducible tyrosinase of a wild strain of Bt was identified and partially characterized. SIGNIFICANCE AND IMPACT OF THE STUDY: The distinct properties of Bt tyrosinase are important to the application of Bt as a biology pesticide.

Bacillus thuringiensis↗
PubMed2001

Pilot study of a specific dietary supplement in tumor-bearing mice and in stage IIIB and IV non-small cell lung cancer patients.

Previously, a specific dietary supplement, selected vegetables (SV), was found to be associated with prolonged survival of stage III and IV non-small cell lung cancer (NSCLC) patients. In this study, several anticancer components in SV were measured; the anticancer activity of SV was assessed using a lung tumor model, line 1 in BALB/c mice. SV was also used in conjunction with conventional therapies by stage IIIB and IV NSCLC patients whose survival and clinical responses were evaluated. A daily portion (283 g) of SV was found to contain 63 mg of inositol hexaphosphate, 4.4 mg of daidzein, 2.6 mg of genistein, and 16 mg of coumestrol. Mouse food containing 5% SV (wt/wt) was associated with a 53-74% inhibition of tumor growth rate. Fourteen of the 18 patients who ingested SV daily for 2-46 months were included in the analyses; none showed evidence of toxicity. The first lead case remained tumor free for > 133 months; the second case showed complete regression of multiple brain lesions after using SV and radiotherapy. The median survival time of the remaining 12 patients was 33.5 months, and one-year survival was > 70%. The median survival time of the 16 "intent-to-treat" patients (including ineligible patients) was 20 months, and one-year survival was 55%. The Karnofsky performance status of eligible patients was 55 +/- 13 at entry but improved to 92 +/- 9 after use of SV for five months or longer (p < 0.01). Five patients had stable lesions for 30, 30, 20, 12, and 2 months; two of them, whose primary tumor was resected, used SV alone and demonstrated an objective response of their metastatic tumors. In addition to the two lead cases, eight patients had no new metastases after using SV. Three patients had complete regression of brain metastases after using radiotherapy and SV. In this study, daily ingestion of SV was associated with objective responses, prolonged survival, and attenuation of the normal pattern of progression of stage IIIB and IV NSCLC. A large randomized phase III clinical trial is needed to confirm the results observed in this pilot study.

Adult↗
PubMed1999

DNA polymerase C of the thermophilic bacterium Thermus aquaticus: classification and phylogenetic analysis of the family C DNA polymerases.

Bacterial family C DNA polymerases (DNA pol IIIs), the major chromosomal replicative enzymes, have been provisionally classified based on primary sequences and domain structures into three classes: class I (Escherichia coli DNA pol C-type), class II (Bacillus subtilis DNA pol C-type), and class III (cyanobacterial DNA pol C-type), respectively. We have sequenced the structural gene encoding the DNA pol C catalytic subunit of the thermophilic bacterium Thermus aquaticus. This gene, designated the Taq DNA pol C gene, contains a 3660-bp open reading frame which specifies a polypeptide of molecular weight of 137,388 daltons. Comparative sequence analyses revealed that Taq DNA pol C is a class I family C DNA polymerase. The Taq DNA pol C is most closely related to the Deinococcus radiodurans DNA pol C. Although a phylogenetic tree based on the class I family C DNA pols is still in the provisional stage, some important conclusion can be drawn. First, the high-G+C and the low-G+C Gram-positive bacteria are not monophyletic. Second, the low-G+C Gram-positive bacteria contain multigenes of family C DNA pols (classes I and II). Third, the cyanobacterial family C DNA pol, classified as class III because it is encoded by a split gene, forms a group with the high-G+C Gram-positive bacteria.

Amino Acid Sequence↗
PubMed1999

Primary structure of the DNA polymerase I gene of an alpha-proteobacterium, Rhizobium leguminosarum, and comparison with other family A DNA polymerases.

The structural gene for DNA polymerase I of Rhizobium leguminosarum was determined. The rhizobium DNA polymerase I consists of 1016 amino acid residues with a calculated molecular weight of 111,491 Dalton. The amino acid sequence comparison with E. coli DNA polymerase I, Thermus aquaticus DNA polymerase I, and Rickettsia prowazekii DNA polymerase I showed that, although 5'-nuclease and DNA polymerase domains are highly conserved, 3' to 5' exonuclease domains are much less conserved. While both R. leguminosarum and R. prowazekii belong to the alpha subdivision of the Proteobacteria on the basis of 16S ribosomal RNA phylogeny, the primary structure of the DNA polymerase I is quite different; the rhizobium DNA polymerase I has 3' to 5' proofreading exonuclease, but the rickettsia DNA polymerase I does not.

Amino Acid Motifs↗
PubMed1998

The hyperthermophilic bacterium Thermotoga maritima has two different classes of family C DNA polymerases: evolutionary implications.

Bacterial DNA polymerase III (family C DNA polymerase), the principal chromosomal replicative enzyme, is known to occur in at least three distinct forms which have provisionally been classified as class I ( Escherichia coli DNA pol C-type), class II ( Bacillus subtilis DNA pol C-type) and class III (cyanobacteria DNA pol C-type). We have identified two family C DNA polymerase sequences in the hyperthermophilic bacterium Thermotoga maritima. One DNA polymerase consisting of 842 amino acid residues and having a molecular weight of 97 213 belongs to class I. The other one, consisting of 1367 amino acid residues and having a molecular weight of 155 361, is a member of class II. Comparative sequence analyses suggest that the class II DNA polymerase is the principal DNA replicative enzyme of the microbe and that the class I DNA polymerase may be functionally inactive. A phylogenetic analysis using the class II enzyme indicates that T.maritima is closely related to the low G+C Gram-positive bacteria, in particular to Clostridium acetobutylicum, and mycoplasmas. These results are in conflict with 16S rRNA-based phylogenies, which placed T.maritima as one of the deepest branches of the bacterial tree.

Amino Acid Sequence↗
PubMed1998

Detection of Rickettsia sibirica in ticks and small mammals collected in three different regions of China.

The primers Rr 190.70p and Rr 190.602n were used to detect spotted fever group (SFG) rickettsiae by polymerase chain reaction (PCR) in ticks and small mammals collected in three different regions of China. The obtained results indicated that specific DNA fragments of SFG rickettsiae were amplified from Dermacentor silvarum, D. sinicus, D. auratus, Haemaphysalis concinna, H. wellingtoni, H. yeni, Apodemus agrarius, Microtus fortis. Clethrionomys rufocanus, Ondatra zibethica, Rattus flavipectus and hedgehog. The PCR product were digested with restriction endonucleases PstI and RsaI and the obtained electrophoretic profiles were compared with those of the prototype strains of SFG rickettsiae by the restriction fragment length polymorphism (RFLP) technique. The comparisons showed that the profiles were identical to those of Rickettsia sibirica. In addition, three new isolates of R. sibirica were obtained from H. yeni, D. sinicus and hedgehog, and designated NH-95, BJ-95 and BHJ-95, respectively. These results not only demonstrated a horizontal transmission of the rickettsiae between ticks and hosts but also suggested that R. sibirica is widely distributed in China and its hosts and vectors are various, all that indicating the existence of natural foci of North Asia tick-borne spotted fever specific to China.

Animals↗
PubMed1997

Arterial supply to the hippocampal formation.

Arterial supply of hippocampal formation in humans has been studied by many investigators in the past. More recently, investigation of correlation of complex partial seizure with mesial temporal sclerosis has brought a resurgence of interest in studying the hippocampus. This article discusses arterial architecture of the hippocampal formation.

Angiography↗
PubMed1997

Venous architecture of cerebral hemispheric white matter and comments on pathogenesis of medullary venous and other cerebral vascular malformations.

The parenchymal veins, especially the deep medullary veins, of the cerebral hemispheres were studied in detail by analyzing the stereoroentgenograms of multiple brain slices of postmortem injected brain specimens (injected into the internal carotid arteries in 17 cases and into the jugular veins in 12 cases). The presence of four zones--the first (or outer), the second (or candelabra), the third (or palmate) and the fourth (or subependymal) zone--of venous convergence was confirmed within the centrum semiovale, particularly in the frontoparietal area. Other venous convergences such as those related to the optic radiation in the para-atrial area were also found. Arterial branching zones were also observed in the areas similar to those of the medullary veins. It appears that these converging zones are created by rapidly growing crossing nerve fiber tracts, i.e., projection, commissural, and association fibers which grow rapidly during intrauterine and postnatal life. Pathogenesis of medullary venous malformation is also discussed from anatomical viewpoint, venoarchitecture of the pial, parenchymal, and subependymal veins and of the dural venous sinuses. The possibility of a similar mechanism (partial, mild, repetitive venoocclusive disease developing over a long period with fluctuating venous pressure) leading to formation of most (if not all) cases of medullary venous malformation and in some, if not many, cases of cerebral vascular malformations [aside from gene abnormality (chromosome 7) in familial cavernous angiomatosis, particularly in Hispanic American or other familial hereditary conditions] has been postulated.

Cerebral Cortex↗
PubMed1996

A rare (arteriolo-)capillomedullary venous anomaly of the cerebellum.

A rare (arteriolo-)capillomedullary venous anomaly of the cerebellum was examined with CT, MRI, and angiography. Unlike the usual venous angioma, this case had such extraordinary features as: infratentorial location, involvement of the whole left cerebellum, an arteriolocapillary component and a history of progressive vomiting and chronic constipation in a 7-year-old boy. CT and MRI were consistent with an extensive vascular malformation, but the actual diagnosis was reached by angiography.

Cerebellar Neoplasms↗
PubMed1994

Mutants of smooth muscle myosin light chain kinase at tryptophan 800.

The importance of Trp 800 in the calmodulin-binding site of myosin light chain kinase was investigated. Truncation mutants from Leu 447 to the C-terminus were expressed in E. coli and these were modified by point mutations of Trp 800 to Gly, Cys, Leu and Tyr. Trp at this position was more effective than any of the other residues. The Leu mutant was partially active and its Km for calmodulin decreased from about 10 nM to 175 nM. The Tyr mutant had detectable activity but the other two mutants were inactive and did not bind calmodulin. Thus Trp at position 800 is critical. The activity of the Leu mutant at high calmodulin concentrations was less than the wild-type mutant, about 20%. This suggests that the binding of calmodulin does not release inhibition in an all-or-none mechanism and that other intramolecular interactions are important.

Animals↗
PubMed1994

The utero-placental circulation, eugenics and the prevention and treatment of high risk pregnancies.

Through systematic experimental and clinical studies, the physiological regulation of utero-placental circulation and the relation of the disturbance in this acirculation to pathogenic mechanisms of high risk pregnancies-Intrauterine Growth Retardation (IUGR) and Pregnancy-induced hypertension (PIH) were explored. The pharmacological effects and mechanism of a Chinese herbal medicine-Qingxintong in improving, the utero-placental circulation and the therapeutic efficacy in treatment of IUGR and PIH, both accompanied by disturbance of utero-placental circulation, were investigated as well.

Acetophenones↗
PubMed1994

Development of posterior fossa dural sinuses, emissary veins, and jugular bulb: morphological and radiologic study.

PURPOSE: To report the anatomic and radiologic development of the transverse, sigmoid, and occipital sinuses, the emissary veins, and the jugular bulb formation from the jugular sinus in humans before and after birth. METHODS: Roentgenograms of 33 injected brains showing the cranial venous system in human fetuses from 3 to 7 months of gestational age and cerebral angiograms of newborns and infants up to 6 years of age (23 clinical cases) were made and analyzed in detail. Special attention was focused on the inner diameters of the transverse and sigmoid sinuses and of the internal jugular veins, particularly at the sigmoid sinus-internal jugular vein junction. RESULTS: Marked increase in venous flow from the rapidly growing cerebral hemispheres leads to ballooning of the transverse sinuses in the absence of an increase in the inner diameters of the sigmoid and jugular sinuses. The ballooning also results in formation of the occipital sinus, marginal sinus around the foramen magnum, and emissary veins. The formation of the jugular bulbs from the jugular sinuses begins after birth when a shift from a fetal to a postnatal type of circulation (or from a lying-down position to an erect posture) takes place. CONCLUSION: The morphological changes of the posterior fossa dural sinuses, emissary veins, and jugular bulb are closely related to the development of the brain, shift to postnatal type of circulation, and postural hemodynamic changes.

Cerebral Angiography↗
PubMed1993

Concerning stimulation by injected fluoroaluminate of the sodium efflux in barnacle muscle fibers.

Single barnacle muscle fibers from Balanus nubilus were used primarily to examine the validity of two ideas: first, that the injection of KF stimulates the ouabain-insensitive Na+ efflux, and that this action is potentiated by adding AlCl3 (Al) in a low concentration to the solution of KF prior to injection. And second, that the injection of a KF-AlCl3 solution into ouabain-poisoned, K(+/-)-depolarized fibers elicits a stimulatory response resembling that obtained by injecting GTP. The results of this study are as follows: injection of 0.5 M KF into unpoisoned fibers causes a sustained rise in the resting Na+ efflux. However, injection of a 0.5 M KF, 10(-3) M AlCl3 solution leads to a reduced rather than an augmented response. Whereas injection of 0.5 M KF into ouabain-poisoned fibers elicits a marked stimulatory response, the injection of 0.5 M KF, 10(-3) M AlCl3 reduces the remaining Na+ efflux. Injection of KF-AlCl3 in equimolar concentrations, e.g., 0.25 M, elicits a response that is significantly larger than that obtained by injecting 0.25 M KF. A dose-response curve indicates that a 0.2 M solution of fluoroaluminate probably represents an optimal concentration. Injection of 0.3 M KF following peak stimulation by injecting 0.3 M AlCl3 completely reverses this response to Al. In sharp contrast, injection of a 0.3 M KF, 0.3 M AlCl3 mixture following peak stimulation by injecting 0.3 M AlCl3 is ineffective. Injection of KF into ouabain-poisoned, K+ depolarized fibers does not always cause sustained stimulation of the remaining Na+ efflux.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1993

The reduction of the inhibitory effect of aluminum on Na+ efflux in barnacle muscles fibers by preinjecting phosphate.

The object of the present study was to test the hypothesis that the pre-enrichment of single muscle fibers from the barnacle Balanus nubilus with inorganic phosphate may protect the basal Na efflux from the inhibitory effect of Al injection. This approach was adopted in the light of evidence that the preinjection of ATP fails to stop the Na efflux in unpoisoned fibers from falling following the injection of Al. The results of the experiments are as follows: (i) Preinjection of K2HPO4 into unpoisoned fibers reduces the magnitude of the inhibitory effect on the basal Na efflux of injected Al in a dose-dependent manner but fails to completely stop it from occurring. (ii) Injection of K2HPO4 following Al into unpoisoned fibers fails to arrest or reverse the inhibitory effect of injected Al. (iii) Injection of K2HPO4 in a concentration as high as 0.5 M is without effect on the course of the basal Na efflux. (iv) Injection of K2HPO4 into ouabain-poisoned fibers fails to stop Al from stimulating the ouabain-insensitive Na efflux. Injection of K2HPO4 following peak stimulation by injecting Al is also without effect. (v) Injection of K2HPO4 in a concentration as high as 0.5 M is without effect on the course of the ouabain-insensitive Na efflux. Collectively, the results obtained with unpoisoned 'hypersensitive' fibers are consistent with the view that a significant fraction of the injected inorganic phosphate binds Al3+, and hence protects the basal Na efflux from the untoward action of Al3+.

Aluminum↗