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L X Xu

Publications and source records attributed to L X Xu.

72 records · Page 4Linked to original sources
PubMed1985

The complete amino-acid sequence of the proteinase inhibitor B from the root of the arrowhead (Sagittaria sagittifolia L.).

After reduction and alkylation of the disulfide bonds of the proteinase inhibitor B from the root of the arrowhead (Sagittaria sagittifolia L.) followed by CNBr cleavage three peptide fragments with 68, 62 and 11 amino-acid residues could be separated on DEAE-Sepharose CL-6B. The peptides or the inhibitor itself were further specifically cleaved either by trypsin or by the mixture of (CH3)2SO/HCl/HBr at the arginyl- and the tryptophyl-peptide bond, respectively. The complete amino-acid sequences of the peptides were determined by manual solid phase DABITC/PITC double coupling micro-method and the primary structure of the arrowhead inhibitor B consisting of 141 amino-acid residues was then elucidated. Twenty pairs of amino-acid residues are repeated in the molecule of this inhibitor, three of these pairs even occur three times. The possible locations of the reactive sites are discussed. On the basis of sequence comparisons between this inhibitor and all other serine proteinase inhibitors the arrowhead inhibitor may belong to a new family.

Amino Acid Sequence↗
PubMedDate not supplied

Microvascular thermal equilibration in rat spinotrapezius muscle.

The current study investigates heat exchange in the thermally significant countercurrent paired vessels of the rat spinotrapezius muscle. Detailed tissue surface temperatures under normal (after the microvascular surgery) and pharmacologically vasodilated states were measured using high-resolution infrared thermography. During vasodilation, a measurable thermal disturbance was observed above the first-order feeding vessel pair. The measured tissue temperatures were compared with those predicted by modifying the theoretical model for two-dimensional muscle preparations given by Zhu et al. (Zhu, L., D. E. Lemons, and S. Weinbaum. Ann. Biomed. Eng. 24:109-123, 1996). They were found in good agreement. The Weinbaum-Jiji k(eff) theory (Weinbaum, S., and L. M. Jiji. J. Biomech. Eng. 107:131-139, 1985) for heat exchange between the paired vessels and their surrounding tissue was also examined in this muscle. A close agreement was obtained between the theoretically predicted k(eff) and the measured value calculated using a fin approximation for the tissue layer. This experimental study revealed for the first time the nonequilibration between blood vessels and the surrounding tissue, where the enhancement in k(eff) due to the incomplete countercurrent heat exchange is comparable to the tissue axial conduction.

Animals↗
PubMedDate not supplied

Thermoregulation in the canine prostate during transurethral microwave hyperthermia, Part I: Temperature response.

In this research, experiments were performed to study thermoregulation in the canine prostate during microwave hyperthermia. The transurethral thermal therapy (T3) system provided by Urologix, Inc. was used to impose microwave heating in the canine prostate. Five types of temperature responses to different microwave power levels as time varies, including both damped and sustained oscillatory temperature responses, have been observed. Decreases in prostatic tissue temperature during the microwave heating are believed to be caused by the increase in local blood flow stimulated by tissue temperature elevations. In this study, the characteristic temperatures and time associated with each response. This work will help to provide a better understanding of how tissue temperature is regulated within the canine prostate during transurethral microwave hyperthermia. Results of the present study offer an experimental foundation for a more detailed theoretical analysis on the temperature distribution based on the power input and local blood perfusion.

Animals↗
PubMedDate not supplied

Thermoregulation in the canine prostate during transurethral microwave hyperthermia, Part II: Blood flow response.

Recent studies on transurethral-applied local hyperthermia in both the canine and human prostate have revealed significant effects of natural thermoregulation on the therapeutical results in the prostate. Using a thermal clearance method, blood perfusion rates were measured within different regions in the canine prostate under normal and hyperthermic conditions. It has been found that the canine-prostatic blood perfusion is strongly linked to the geometrical location within the gland, the local tissue temperature, and the imposed thermal dosage. Results from this research are expected to provide a better understanding of the thermoregulatory behaviour in the canine prostate, and thus lay an important foundation for predicting tissue temperature in the human prostate during transurethral microwave hyperthermia.

Animals↗