PubMed Health⌕ Search

Biomedical subjects

Y K Liu

Publications and source records attributed to Y K Liu.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Effect of intestinal lymph on blood pressure of rat].

The effect of intestinal lymph on blood pressure in rats was observed by the methods of lymph drainage and lymph infusion. The results obtained are as follows: (1) After 150 min of the lymph drained through the cannula of intestinal lymph duct, the blood pressure was significantly lower than that of the sham group (P < 0.05). (2) Equivalent albumin or intralipid infusion was not able to prevent the decrease in blood pressure when the lymph was lost. But in jugular-intestinal lymph duct shunt group, no significant blood pressure decrease could be seen during the drainage procedure for 4 h. (3) The blood pressure of rat with serious hemorrhagic shock could be increased significantly with a little amount of intestinal lymph infusion, and the rats survived longer than those of the control group (P < 0.05-0.01). The above results suggest that the intestinal lymph may play an important role in maintenance of blood pressure, in addition to the known function of lymphatic system by returning tissue fluid to blood and maintaining circulating blood volume.

Animals↗
PubMed1995

[Modulation of lymph microcirculation by sympathetic nerve during hemorrhagic shock of rat].

The present study was undertaken to examine the effect of sympathetic nerve on the changes of lymph microcirculation during hemorrhagic shock. After greater splanchnic nerve transection, changes of contractility of mesenteric micro-lymphatics (ML) in denervated rat were visualized and recorded by using a vital microscope with TV recorder during hemorrhagic shock and followed by refusion of withdrawn blood and infusion of saline. Results obtained showed that ML spontaneous contraction frequency, overall lymphatic contractile activity (Index II) and lymphatic dynamics (L. D-Index) decreased significantly after denervation. The ML spontaneous contractility decreased during hemorrhagic shock both in the denervated group and the intact group. During refusion of withdrawn blood and infusion of normal saline periods, the ML spontaneous contractility in the intact group was significantly higher than that of the pre-shock period, but in the denervated group it remained at a level, lower than that of the intact group (P < 0.01). During the post-infusion period the blood pressure was still much lower in the denervated than that of the intact group. The above results suggest that ML contractility shows decrease in hemorrhagic shock, while infusion of blood and normal saline may increase ML contractility and enhance blood pressure. The sympathetic nerve may play a modulation role to the recovery process of shock.

Animals↗
PubMed1992

Priapism associated with asplenic state.

Priapism may be primary (idiopathic) or secondary to sickle cell anemia, trauma, leukemia, drugs, venous thromboembolic diseases, and other less common disorders. This study concerns 21 patients with priapism treated during a period of ten years. Nine patients (43%) had sickle cell anemia. Of the 12 individuals (57%) classified as idiopathic, 3 (25%) had previously undergone surgical splenectomy for benign conditions. Considering the propensity for this unusual condition to develop in patients with hemoglobinopathy-induced hyposplenism, the possibility of a relationship between the asplenic state and priapism is considered.

Adult↗
PubMed1992

Biomechanical analysis of a step-cut technique for flexor tendon repair.

We compared the strength of a new step-cut technique for flexor tendon repair with that of the widely used Kessler-Tajima technique, giving special attention to the relative contributions of the core and epitendinous sutures. 36 flexor digitorum profundus tendons from human cadavers were used. Corresponding digits from the same donor were paired, and the two tendons of each pair were placed in the Kessler-Tajima and step-cut groups, respectively. Each group had three subcategories of repair: (1) core repair alone; (2) epitendinous repair alone; and (3) full repair. In the Kessler-Tajima repair, the core stitch contributed more to ultimate tensile strength, while the epitendinous stitch contributed more to gap formation resistance. In the step-cut repair, however, the epitendinous stitch contributed more to both measures of strength. The full step-cut repair was 65% stronger in resisting gap formation and had 84% more ultimate tensile strength than the full Kessler-Tajima repair. We attribute the greater strength of the step-cut repair to the additional number of epitendinous loops, which lie perpendicular to the long axis of the tendon.

Cadaver↗
PubMed1992

Failure analysis of a beam-column under oblique-eccentric loading: potential failure surfaces for cervical spine trauma.

For a cantilever beam-column with one end built-in and the free end subjected to an oblique-eccentric arbitrary concentrated force, general formulas to produce failure were derived. The original generalized uniform solution to the oblique-eccentric buckling problem was obtained. The Secant formula and Euler's formula were proved to be specific cases in this general solution. The load ratio, F/aE, was derived as functions of the force acting direction, alpha, the slenderness ratio, L/r, as well as the eccentricity ratio, ec/r2. Material and buckling failures aspects were combined in a uniform structural failure analysis. Safe regions for the load ratio, F/aE, were visualized in the three-dimensional (F/aE)-alpha-(L/r) space with the eccentricity ratios, ec/r2, as a parameter. The column failure factor, kL, was shown to be a key index controlling both aspects of failure as well as the orientation of the second stiffest region. The angle alpha E = tan-1 (2L/pi e) for kL = pi/2 is the singular point for both strength and buckling failure, and alpha II = tan-1 (2L/3e) for KL = 0 is the upper bound of the second stiffest region. The feasible domain of the second stiffest region is bounded by alpha E and alpha II both of which are only functions of geometrical properties. The implications of these analyses for the experimental validation of cervical spine trauma are discussed.

Biomechanical Phenomena↗
PubMed1992

[Monitoring of gentamicin blood level].

A prospective randomized comparison of blood concentration as well as manifestations of ototoxicity and nephrotoxicity in groups with conventional and individualized administration of gentamicin was carried out in a total of 106 hospitalized patients. Therapeutic serum concentrations (peak 4-9 mg/L, though less than 1 mg/L) were achieved in 50% of the patients of conventional group and in all the patients of individualized group. Incidence of auditory and renal toxic reactions was high in the conventional group, being 27% and 30% respectively, while in the individualized group, the corresponding figures were 2.8% and 0%. Therefore, individualized administration of gentamicin based on data from therapeutic drug monitoring can markedly decrease the toxic effect and increase the therapeutic efficacy. It is worthwhile to use this kind of administration clinically.

Adult↗
PubMed1991

Thermal response of rat fibroblasts stably transfected with the human 70-kDa heat shock protein-encoding gene.

The major heat shock protein hsp70 is synthesized by cells of a wide variety of organisms in response to heat shock or other environmental stresses and is assumed to play an important role in protecting cells from thermal stress. We have tested this hypothesis directly by transfecting a constitutively expressed recombinant human hsp70-encoding gene into rat fibroblasts and examining the relationship between the levels of human hsp70 expressed and thermal resistance of the stably transfected rat cells. Successful transfection and expression of the gene for human hsp70 were characterized by RNA hybridization analysis, two-dimensional gel electrophoresis, and immunoblot analysis. When individual cloned cell lines were exposed to 45 degrees C and their thermal survivals were determined by colony-formation assay, we found that the expression of human hsp70 conferred heat resistance to the rat cells. These results reinforce the hypothesis that hsp70 has a protective function against thermal stress.

Animals↗
PubMed1991

Bone-particle-impregnated bone cement: an in vivo weight-bearing study.

To evaluate an experimental inorganic-bone-particle-impregnated bone cement, canine hip prostheses were implanted in dogs using a regular bone cement on one side and the experimental bone cement on the other. In a preliminary feasibility study, bone ingrowth into the resorbed bone-particle spaces was established 3 months after implantation in three dogs. In a more detailed study, twenty-eight (28) dogs were divided in four groups to delineate the effects of time on the phenomena of bony ingrowth. One month after implantation, active bone ingrowth into the bone cement was obvious. By 3 months postimplantation, the ingrowth appeared to have traversed the thickness of the bone-particle-impregnated cement. By the fifth month, most of the interconnected inorganic bone particles were replaced by new bone. At the end of a year, the ingrown bone was mature and negligible new bone activity was present. Biomechanical pushout tests closely corroborated the histologic observations. The maximum shear strength of the cement/bone interface of the experimental side reached 3.6 times that of the control side at 5 months postimplantation. No further improvements were seen at 12 months postimplantation. A viable bone/cement interface may result in a better orthopedic implant fixation system by combining the advantages of both cement for immediate rigidity and biological ingrowth for longterm stability.

Animals↗
PubMed1991

Thigh bleeding time as a valid indicator of hemostatic competency during surgical treatment of patients with advanced renal disease.

We compared the usefulness of the modified Ivy bleeding time performed in the forearm (arm bleeding time) with that performed in the thigh (thigh bleeding time) as an indicator of hemostatic competence during surgical treatment in 16 patients with chronic renal failure. In 22 normal adults, the arm bleeding time (mean plus or minus standard deviation, 6.6 +/- 1.4 minutes) was significantly longer than the value in the thigh (mean plus or minus standard deviation, 4.1 +/- 1.3 minutes) (p less than 0.001), and there was no correlation between arm and thigh bleeding time. Preoperatively, the arm bleeding time in patients with renal disease was markedly prolonged (greater than 20 minutes) in 15 patients and slightly prolonged in one patient. There was no abnormal perioperative bleeding in 13 patients whose preoperative thigh bleeding time was seven minutes or less. Prolonged and excessive perioperative bleeding was observed in three patients whose thigh bleeding time was 8.0, 9.5 and 26.5 minutes. These findings suggest that thigh bleeding time is a better indicator of competence of primary hemostasis during the operation than the arm bleeding time in patients with advanced renal failure.

Adult↗
PubMed1990

Treatment of radiation or cyclophosphamide induced hemorrhagic cystitis using conjugated estrogen.

Five patients with severe hemorrhagic cystitis induced by radiation and/or cyclophosphamide were systematically treated with conjugated estrogen. Two patients received conjugated estrogen twice each day (1 mg. per kg.) intravenously, followed on day 3 and thereafter by 5 mg. per day orally. Hematuria decreased markedly 6 to 8 hours after the initial dose and urine color became light yellow within 1 to 3 days. The other 3 patients received 5 mg. conjugated estrogen per day orally and urine color became clear within 4 to 7 days. Hematuria did not recur during 12 to 22 months in 4 patients who received daily conjugated estrogen (1.25 mg.). However, transient episodes of mild hematuria persisted in 1 patient during the 3-month followup despite a higher dose of conjugated estrogen (10 mg. per day). Complications, including thromboembolism and other side effects associated with conjugated estrogen, were not observed in these patients. We postulate that conjugated estrogen controls hematuria in hemorrhagic cystitis by decreasing the fragility of the mucosal microvasculature of the bladder.

Adult↗
PubMed1990

Fatigue life improvement of nitrogen-ion-implanted pedicle screws.

An experimental study of the fatigue life of pedicle screws and their nitrogen-ion-implanted counterparts was conducted. Nitrogen-ion implantation parameters were varied in the first part of the study to obtain the best implantation characteristics. Using this optimal parameter for N(+)-implantation, the performance of two matched groups were compared at two bending moments near the "knee" of the S-N curves. At 3.96 N-m and 5.09 N-m of applied bending moments, the increase in the mean fatigue life for the former was 98% and for the latter 20%. The 98% prolongation was statistically significant at P less than 0.005; however, the 20% increase was statistically insignificant (P less than 0.1). The implantation depth is about 0.1 mu in the near surface of the screw. This appears to be thick enough to inhibit crack initiation at 3.96 N-m, but only marginally at 5.09 N-m. Increasing the implantation depth has the potential of increasing the fatigue life at the higher bending moments.

Bone Screws↗
PubMed1989

The second stiffest axis of a beam-column: implications for cervical spine trauma.

Based on an idealized model of a homogeneous, isotropic beam-column, the second stiffest axis under static loading was derived. The maximum allowable force for the second stiffest axis was then examined. The ratio of the maximum allowable forces of the second stiffest axis to the stiffest axis was established. The stiffness ratio of the second stiffest axis to the stiffest axis was also found. Taking buckling into consideration, the safe load region for all possible acting directions was derived. The implications of the idealized model for cervical spine trauma are discussed.

Biomechanical Phenomena↗
PubMed1988

Moment-rotation relationships of the ligamentous occipito-atlanto-axial complex.

The relationships between applied pure moments at the occiput (C0) and the resulting rotations at the atlanto-occipital (C0-C1) and atlanto-axial (C1-C2) joints are quantified. In axial twist, with a moment of 0.3 Nm, a mean rotation of about 2.5 degrees and 23.3 degrees was observed at C0-C1 and C1-C2 units respectively. Both the atlas and axis contributed to produce lateral bending motion. The ratio between extension and flexion rotations at C0-C1 was 2.5:1. Lateral bending and axial rotations were strongly coupled to each other. The occipito-atlanto-axial complex exhibited a large 'neutral zone' compared to lower cervical spine segments. The likely clinical significance of these findings are discussed.

Aged↗
PubMed1988

Response of the ligamentous lumbar spine to cyclic bending loads.

The effect of a "pure" cyclic flexion bending moment on the three-dimensional load-displacement behavior of fresh ligamentous lumbar spine was investigated. The load-displacement behavior, for 11 L1-sacrum specimens, pre- and post-cyclic fatigue bending tests were quantified using a Selspot II system. A special fixture was designed to mount the specimen within the MTS system to administer "pure" cyclic flexion bending, under displacement control, for 5 hours. The testing was accomplished in a 100% humidity chamber at 0.5 Hz. The maximum cyclic bending moment, based on the literature dealing with loads experienced by the spine during activities involving lifting, was set at 3.0 Nm. An increase in motion of the order of 10% in the extension loading mode was observed. The increase in motion in other loading modes was not significant. In the extension loading mode, the increase in the anteroposterior displacement (retrodisplacement) in general was higher than the corresponding rotation component. The results suggest that the bending moment of low magnitude, usually experienced by the spine during activities of daily living, alone may not trigger the mechanical failure processes in the disc. The presence of high axial compressive loads on the disc seems to be the main contributing factor in this process. The presence of bending moments and axial twist along with axial compressive load may accelerate the unstable processes leading to low back pain.

Humans↗