Biomedical subjects

S H Liu

Publications and source records attributed to S H Liu.

At least 127 records · Page 7Linked to original sources

PubMed1995

Current review. Functional knee bracing.

Recent surgical advancements in anterior cruciate ligament reconstructions have led to better results in the treatment of knee injuries. Functional knee braces have been prescribed in greater number, leading to an increased production of commercially available braces. The effectiveness of braces remains controversial because of inconsistency in investigations of functional knee braces. This article reviews the historical background, biomechanics, and static and dynamic testing of knee braces and compares custom and off-the-shelf functional knee braces. Factors such as hinge design and soft tissue compliance, which may affect functional knee bracing, are discussed.

Anterior Cruciate Ligament Injuries↗

PubMed1995

Collagen in tendon, ligament, and bone healing. A current review.

Cells that produce a particular type of collagen under normal physiologic circumstances can be induced by certain local triggers to change the amount and type of collagen synthesized. This has become most apparent during bone, tendon, and ligament healing, where cells that once produced the collagen of normal intact tissue are induced to synthesize different types of collagen at the repair site of injured tissue. For example, Type III collagen, not a major component of the extracellular matrix in normal tendons, is believed to be of great advantage during the healing process because of its ability to form rapid crosslinks and precariously stabilize the repair site. Although much is known about the gross histologic changes occurring during tissue healing, little is known about the specific role of the individual collagen types or what influences their development. This review addresses the role of collagen in normal and healing bone, tendon, and ligament. Much experimental effort is needed to uncover the distribution and function of the collagen types within connective tissue elements and the effect of growth factors on the phenotype of collagen produced in these tissue, with the ultimate goal of developing clinical manipulations that take advantage of the unique properties of each type of collagen.

Anterior Cruciate Ligament↗

PubMed1995

Biomechanics of two types of bone-tendon-bone graft for ACL reconstruction.

We measured the initial fixation strength of a new graft, bone-hamstring-bone (BHB), for reconstruction of the anterior cruciate ligament (ACL) in 79 porcine knees and compared it with that of the normal porcine ACL and of the bone-patellar tendon-bone (BPB) graft. All specimens were subjected to ultimate load to failure and cyclic loading tests to assess the amount of graft slippage. The ultimate load to failure for the intact ACL was 1266 +/- 250 N, for the BPB graft 663 +/- 192 N and for the BHB graft 354 +/- 92 N (p < 0.01). After cycling to 235 N (the maximum load for all groups without failure) the average residual displacements after removal of the load for the ACL, BPB and BHB grafts were 0.031 +/- 0.013 cm, 0.078 +/- 0.033 cm, and 0.322 +/- 0.222 cm, respectively (p < 0.01). For the BHB graft the load to failure was less and the amount of graft slippage was more than for the BPB graft. Neither form of reconstruction was as strong as the intact ACL.

Animals↗

PubMed1995

A new operation for chronic lateral ankle instability.

We have treated 45 patients (47 ankles) for chronic lateral instability by a new reconstructive procedure. The operation includes lateral shift of the entire lateral capsule-ligament complex and proximal advancement of the talocalcaneal ligament and the inferior extensor retinaculum. We reviewed 39 patients (39 ankles) at a mean of 4.6 years (2 to 7) after operation. There were 29 men and 10 women with an average age of 27 years (19 to 43); 11 of them were competitive college-level athletes and 28 were recreational athletes. The functional rating was excellent in 26 patients, good in 8, fair in 3 and poor in 2. Thirty-six patients (92%) were satisfied with the result and 34 (9 of 11 college-level athletes and 25 of 28 recreational athletes) have been able to return to their preinjury level of sport. At the last review, there had been only three episodes of recurrent ankle instability, all in recreational athletes; none had required further surgery. The unsatisfactory results were associated with pre-existing degenerative changes in the ankle.

Adult↗

PubMed1995

Power spectrum of the fast Fourier transform for measurement of standing balance.

Power spectrum of the force moment generated from the fast Fourier transform (FFT) was utilised to evaluate standing balance on a force platform. The principles on generating and analysing an FFT spectrum from the output of the force platform are illustrated. Test-retest reliability of twelve healthy young people (age = 26 +/- 4 years) was performed with the preferred leg stance. The intraclass correlation coefficient (ICC), R, of mean power (P), spectral area (Sx) and maximum power (Px) were 0.89, 0.85 and 0.89 respectively, indicating that the spectral parameters are reliable quantitative measures of balance. Pearson product moment (PPM), r, of these spectral parameters were 0.95, 0.85 and 0.95 respectively showing that these spectral parameters are significantly correlated (p < 0.01). A comparison was made with respect to the one legged stance and two legged stance steadiness. The one legged stance (Sx = 95.75 cm.Hz) was significantly less stable than the two legged stance (Sx = 41.58 cm.Hz) with a value of 9.37. Moreover, the one legged stance was highly correlated to the two legged stance (r = 0.84), indicating that, in general, a subject who has a stable one legged stance should have a stable two legged stance.

Adolescent↗

PubMed1994

Studies on the contracture inducing action of triphenyltin in the mouse diaphragm.

Triphenyltin induces a contracture of the mouse phrenic nerve-diaphragm preparation. This contracture was not inhibited by (+)-tubocurarine, high magnesium or the absence of electrical stimulation. Triphenyltin (0.1 mM) reduced the muscle membrane potential, the amplitude of the muscle action potential and the muscle membrane input resistance. Pretreatment with high K+ (25 mM) or veratridine (1.5 microM; a Na+ channel activator) briefly shortened the onset of the contracture and increased the peak tension of the contracture. Pretreatment with tetrodotoxin (0.3 microM; a Na+ channel blocker) or glycerol (a T tubule uncoupler) however, significantly reduced the triphenyltin-induced contracture. Removing Ca2+ from external solution and prolonged treatment with either caffeine (20 mM) or ryanodine (2 microM) inhibited the triphenyltin-induced contracture. However, a brief treatment with a lower concentration of caffeine (10 mM) potentiated the contracture. 45Ca2+ uptake studies showed that triphenyltin caused the muscle to accumulate Ca2+ which entered from external solution. Pretreatment with trypsin and dithiothreitol (a sulfhydryl-containing reducing agent) blocked the contracture induced by triphenyltin. These results suggest that triphenyltin initially interacts with the sulfhydryl groups of membrane bound proteins (possibly the Na+ channel) to cause depolarization of the muscle fibres. This depolarization triggers the release of Ca2+ from sarcoplasmic reticulum through the mechanism of Ca2+ inducing Ca2+ release, activates the contractile filaments and causes the muscle to contract.

Action Potentials↗

PubMed1994

Serum response factor associated ETS proteins: ternary complex factors and PEA3-binding factor.

An ETS protein binding motif CAGGAT adjoins the 5' side of the Serum Response Element in the c-fos promoter. This sequence is recognized by several ETS proteins which are able to form ternary complexes in the presence of Serum Response Factor. Related sequences, capable of ternary complex formation, are also found in the promoters of immediate early zinc finger proteins. However, similar sequences found in the gamma-actin and c-ets-2 promoters could not bind Ternary Complex Factor. We purified a 60-kDa human ETS protein which could bind the sequence recognized by Ternary Complex Factor, and this protein could bind DNA in the absence of Serum Response Factor. Interestingly, this protein also binds Serum Response Factor in vitro. Therefore the Serum Response Factor DNA-binding/oligomerization domain has affinities for distinct ETS oncoproteins.

Base Sequence↗

PubMed1994

An in vivo comparison of oral 5-iodo-2'-deoxyuridine and 5-iodo-2-pyrimidinone-2'-deoxyribose toxicity, pharmacokinetics, and DNA incorporation in athymic mouse tissues and the human colon cancer xenograft, HCT-116.

5-iodo-2-pyrimidinone-2'-deoxyribose (IPdR) was recently reported to be converted to 5-iodo-2'-deoxyuridine (IUdR) by an aldehyde oxidase, most concentrated in liver tissue. We questioned whether IPdR could be used as a p.o. hepatotropic prodrug to increase the percentage of IUdR-DNA incorporation into liver tumors compared to normal liver with acceptable systemic toxicity. Athymic nude mice with human colon cancer (HCT-116) xenograft tumors as liver metastases and s.c. flank tumors received daily p.o. boluses (via gastric tubes) of IUdR or IPdR for 6 days. The maximum tolerated dose of IUdR was 250 mg/kg/day and was associated with a > 10% weight loss and a high percentage of IUdR-DNA incorporation (> 5%) into normal bone marrow and intestine. In contrast, animals tolerated escalating doses of IPdR to 1 gm/kg/day without weight loss and with less (1.5-4%) IUdR-DNA incorporation in normal tissues. Pharmacokinetic analysis of p.o. IPdR showed peak plasma levels of IPdR and IUdR within 15-45 min, suggesting efficient conversion of IPdR to IUdR. Aldehyde oxidase activity was found in normal liver tissue but not in other normal or tumor tissues. Additionally, we found a 2-3 times greater percentage of IUdR-DNA incorporation in tumor with IPdR than IUdR at the highest doses used. However, no differential effect in the percentage of IUdR-DNA incorporation was noted between liver metastases and s.c. tumors with either IPdR or IUdR. We conclude that p.o. IPdR offers a greater therapeutic index for tumor incorporation (and presumably radiosensitization) than a similar schedule of IUdR.

Administration, Oral↗

PubMed1994

Potentiation by metal ions of ryanodine contracture of the mouse diaphragm.

The aim of this study was to elucidate the possible mechanism of the potentiating action of metal ions (Cu2+, Hg2+, Ag+ and SeO3(2-)) on the ryanodine-induced contracture of the mouse diaphragm. The ryanodine contracture in the quiescent muscle could be augmented by either electrical stimulation or pretreatment with high K+ of the diaphragm. Lowering the external Ca2+ concentration from 2.5 mM to 1 microM or the addition of 7 microM d-tubocurarine, which abolished the muscle excitability by blocking the receptors of acetylcholine, markedly attenuated the ryanodine contracture. Application of Cu2+, Hg2+, Ag+ and SeO3(2-) but not Ni2+ and Co2+, to quiescent muscle restored the ryanodine contracture. The potentiating effects of Hg2+, Ag+ and high K+ were dependent on the presence of external Ca2+ (2.5 mM) and intact transverse tubular systems but the effects of Cu2+ and SeO3(2-) were not. Treatment with 1 mM dithiothreitol 10 min after the application of metal ions and then subsequent addition of ryanodine abolished the potentiating effects of Hg2+ and Ag+ but not those of Cu2+ and SeO3(2-). Although ryanodine by itself had no effect on 45Ca2+ uptake by the mouse diaphragm, it significantly potentiated the increased 45Ca2+ uptake elicited by Cu2+ and Hg2+. Further elucidation of the interaction between metal ions and ryanodine on the outer sarcolemma showed that all of these metal ions, including the inactive Co2+ and Ni2+, not only decreased the membrane potential but also altered the membrane input resistance, effects which were not correlated with the potentiating effects of the metal ions on the ryanodine contracture.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Arthroscopic treatment of anterolateral ankle impingement.

Fifty-five ankle arthroscopies performed for anterolateral ankle impingement between January 1987 and April 1992 were reviewed for functional outcome and patient satisfaction. There were 33 men and 22 women with an average age of 34 years (range 20-67). All patients reported a previous history of ankle injury, and 60% of the patients had at least one ankle sprain. At an average follow up of 2.6 years (range 1.0-4.5), 87% of the patients had good/excellent results, 98% were satisfied, and 84% returned to their previous sports.

Adult↗

PubMed1994

Meniscal ossicles: two case reports and a review of the literature.

Intrameniscal ossicles of the knee are rare lesions. We present two cases. The first case occurred in a male soccer player who had knee trauma, with radiographic findings of a meniscal ossicle. Meniscal motions were normal, and symptoms resolved with conservative measures. The second case was found in a male athlete with acute medial compartment instability and complex meniscal tears. His medial meniscus, containing the ossicle, was removed. Initial conservative management is recommended for all cases of meniscal ossicle, and arthroscopic resection of the ossicle is recommended for symptomatic cases.

Adult↗

PubMed1994

Partial lateral meniscectomy in athletes.

Arthroscopic partial lateral meniscectomies performed for isolated meniscal tears, without associated ligamentous injury, in 41 athletes between August 1, 1988 and June 1, 1991 were reviewed for clinical and functional outcome. The study population was composed of 27 males and 14 females, with an average age of 26 years (range 17-40). Thirty-seven patients (90%) reported previous trauma to the knee. At an average follow-up of 3 years (range 2-5), 85% of the patients had excellent/good results, and 98% of the athletes returned to full sports activities after an average of 55 days. Patients' prognoses depended on (a) type of meniscal tear and (b) presence/absence of an articular cartilaginous lesion. Athletes who had isolated, longitudinal type tears of the lateral meniscus had the best outcome: 100% achieved excellent/good results and averaged 41 days to return to full sports activities. Athletes with complex meniscal tears and tears associated with articular cartilaginous lesions had the poorest results, achieving 79% and 64% excellent/good results, respectively, and averaging 64 and 78 days, respectively, for return to full sports activities.

Adolescent↗

PubMed1994

Endoscopic anterior cruciate ligament reconstruction: a modified technique for graft passage.

This article describes a simple technique for graft passage during endoscopic anterior cruciate ligament reconstruction. A 0.62 Kirschner wire is used to create a composite graft from either an Achilles tendon allograft or bone--patellar tendon--bone graft. This composite graft is then passed (linearly) from the tibial tunnel to the femoral tunnel without disturbing the soft tissue in the lateral thigh.

Anterior Cruciate Ligament↗

PubMed1994

Arthroscopically assisted rotator cuff repair: correlation of functional results with integrity of the cuff.

Thirty-three patients (35 full-thickness rotator cuff tears) who underwent arthroscopically assisted mini open repair between June 1987 and January 1990 were evaluated for shoulder function and cuff integrity. The study population was composed of 19 women and 14 men with an average age of 63 years (range 35-76) and an average follow-up of 3.7 years (range 2.5-5.1). Functional results were obtained using the UCLA Shoulder Rating Scale. Integrity of the rotator cuff was established by shoulder arthrography at a minimum 2 years postoperatively. UCLA Shoulder Rating Scale showed 86% good/excellent results with 92% patient satisfaction. The shoulder arthrography showed 12 (34%) full-thickness tears, seven (20%) partial tears, and 16 (46%) no tears. The size of the arthrographic defect correlated well with the size of the intraoperative tear. Seventy percent of the large tears had follow-up full-thickness defects and 80% of the small tears had no defect. Eighty percent and 88% good/excellent functional results were achieved in patients with full-thickness defects and no defects, respectively, without significant differences. The size of the tear at the time of the repair is a major determinant of the integrity of the cuff after repair. The integrity of the cuff at follow-up does not determine the functional outcome of the operated shoulder.

Adult↗

PubMed1994

Ganglion cysts of the anterior cruciate ligament: a case report and review of the literature.

Ganglion cysts on the anterior cruciate ligament (ACL) should be suspected in any patient having pain and clicking sensation during terminal knee extension. Previous investigators have reported incidental findings of ganglion cysts on the ACL. However, we report a symptomatic case of a ganglion cyst on the ACL that was treated successfully with arthroscopic debridement.

Adult↗

PubMed1994

Lateral ankle sprains and instability problems.

The lateral ankle complex is the most frequently injured single structure in athletes, consisting of 38% to 45% of all injuries. One-sixth of all sports injury loss time is from ankle sprains. In North America, ankle inversion sprains are considered "de rigeur" for basketball participation.

Ankle Injuries↗

PubMed1994

Arthroscopically-assisted rotator-cuff repair.

We reviewed 44 patients with 44 full-thickness rotator-cuff tears at an average of 4.2 years after arthroscopically-assisted repair. There were 25 women and 19 men aged between 35 and 76 years (average 58); 35% of the shoulders had other intra-articular lesions. Most of the patients (85%) had been discharged from hospital immediately after the operation. The result was rated good or excellent in 84%, 88% of the patients were satisfied, and 64% of the athletes returned to their previous sports. The size of the tear was a determining factor in the outcome.

Adult↗

PubMed1994

Serum response element-regulated transcription in the cell cycle: possible correlation with microtubule reorganization.

The transcriptional response to growth factors and other mitogenic signals is mediated by the serum response elements (SREs) located in the promoters of many immediate early genes, including the c-fos and beta-actin genes. We investigated SRE-regulated transcription in cell cycle-synchronized nuclei and found that a SRE-regulated reporter gene was transcribed actively during G1 and, surprisingly, during G2-M as well. One possible mechanism involved in the latter event is microtubule reorganization. Microtubule disassembly is mimicked by microtubule-disrupting drugs, and we found that these drugs, including colchicine, nocodazole, and vinblastine, could activate SRE-dependent reporter genes, as well as the c-fos protooncogene, in asynchronously growing cells. Taken together, our results suggested a possible relationship between cytoplasmic microtubule dynamics and cell cycle gene expression. Although the detailed molecular mechanisms of drug action are not known, protein phosphorylations may be involved, since drug-induced stimulation could be abrogated by several protein kinase inhibitors. Furthermore, the overexpression of mitogen-activated protein kinase ERK1 could superinduce the stimulation of SRE-dependent reporter gene expression by colchicine and suggests that the microtubule disassembly signal may be transduced by microtubule-associated kinases.

Actins↗