Biomedical subjects

C C Wu

Publications and source records attributed to C C Wu.

At least 127 records · Page 7Linked to original sources

PubMed2000

Integrated backscatter for quantification and risk stratification of blood stagnation in left atrial appendages of patients with rheumatic mitral stenosis.

This study was designed to quantify the blood stagnation in left atrial appendages (LAA) of patients with rheumatic mitral stenosis, and to stratify the risk of spontaneous echo contrast (SEC) for thrombus formation. A total of 45 patients were enrolled in this study. Thirty of the 45 patients had rheumatic mitral stenosis. All the above patients were evaluated for LAA contractility by transesophageal echocardiography. Acoustic density of the stagnant blood was assessed using the integrated backscatter (IBS) mode. Multivariate linear regression analysis showed that the significant independent variables determining relative IBS in LAA were the mitral valve area (p = 0.02) and the atrial fibrillation rhythm (p = 0.0003). In patients with mitral stenosis, the IBS in LAA correlated well with the presence of thrombus (p = 0.004) and SEC (p = 0.002). Using the relative IBS in LAA with 6.8 dB as the cutoff value, the diagnostic sensitivity, specificity, positive predictive value, negative predictive value and accuracy of SEC formation in LAA was 83, 86, 95, 60 and 83%, respectively. Using the relative IBS in LAA with 10.0 dB as the cutoff value, the diagnostic sensitivity, specificity, positive predictive value, negative predictive value and accuracy of SEC with thrombus formation in LAA was 80, 80, 67, 89 and 80%, respectively. In conclusion, the blood stasis in LAA can be objectively quantified using IBS. Utilizing different cutoff values, the acoustic densitometry in LAA enables identification of stagnant blood which represents a risk for the development of either SEC only or SEC with thrombus formation.

Adolescent↗

PubMed2000

Intraventricular isovolumic relaxation flow patterns improve the predicting power of Doppler echocardiography for the left ventricular filling pressure in patients with anterior wall myocardial infarction.

BACKGROUND AND PURPOSE: Previous studies have shown that left ventricular systolic asynchrony affects both the relaxation and filling phases of diastole. The purpose of this study was to delinate how the anterior wall dyssynergy influenced the intraventricular flow redistribution patterns during the isovolumic relaxation (IVR) period, which delineated the changes in diastolic suction performance and, therefore, determined the significant Doppler flow variables for predicting left ventricular filling pressure. METHODS: Seventy-three patients with anterior wall myocardial infarction and dyssynergy were enrolled. Those who exhibited the whole IVR intraventricular flow redistributing toward the mitral apparatus, which indicated the reverse physiologic intraventricular pressure gradient in early diastole, were classified as group B, otherwise, as group A. The Doppler echocardiographic variables of mitral inflow were correlated with the left ventricular end-diastolic pressures (LVEDP). RESULTS: With lower ejection fraction rate and more apical dyssynergy, the group B patients had much slower mitral flow propagation. For group A patients, the independent determinants for LVEDP were the ratio of mitral flow propagation rate to peak velocity in early diastole, the early mitral flow deceleration time and the IVR time, all occurring in early diastole. In contrast, the only independent determinant for LVEDP in group B patients was the ratio of mitral peak flow velocity in early diastole to that in late diastole. CONCLUSIONS: The intraventricular IVR flow patterns could delineate how the left ventricular systolic dyssynergy influenced the diastolic process, and determine which echocardiographic variables were more useful for predicting LVEDP in patients with anterior wall myocardial infarction.

Adult↗

PubMed2000

Prevention of bacteremia in dogs undergoing dental scaling by prior administration of oral clindamycin or chlorhexidine oral rinse.

Dogs with periodontitis were used to determine the efficacy of an oral regimen of clindamycin versus chlorhexidine acetate oral rinse in reducing the total number of bacteria and the incidence of bacteremia before and after dental scaling. Aerobic and anaerobic bacteria, isolated from blood and gingival swab cultures, were identified to genus using an automated system.

Administration, Oral↗

PubMed2000

Stent-based gene therapy.

Delivery of gene therapy to inhibit intimal hyperplasia has been proposed to prevent postangioplasty restenosis. We sought to apply gene therapy by using a stent-based technique. There are several hurdles that must be overcome before gene-stent therapy can be applied successfully in clinical trials. These include increasing the efficiency of gene delivery through atherosclerotic plaque; increasing intramural retention times; preventing the inflammatory reaction that stents coated with biodegradable polymers can elicit; overcoming the risk of systemic gene delivery; and accessing the adventitia via percutaneous approach. We evaluated a gene-stent delivery mechanism based on microporous metal microneedles developed with nanotechnology in an attempt to overcome some of these problems. A novel approach to the transfection of genes by microfabricated technology was evaluated in smooth muscle cells in culture. We demonstrated that microneedles can deliver gene therapy to smooth muscle cells in culture and can produce controlled penetration of the IEL and intima. We conclude that taller microneedles need to be developed to reach the media in diseased human arteries and that this technology has the potential to be incorporated in a stent to deliver gene therapy in atherosclerotic plaque.

Angioplasty, Balloon, Coronary↗

PubMed2000

Continuous infusion of gentamicin into the tarsocrural joint of horses.

OBJECTIVE: To develop a method for continuous infusion of gentamicin into the tarsocrural joint of horses, to determine pharmacokinetics of gentamicin in synovial fluid of the tarsocrural joint during continuous infusion, and to evaluate effects of continuous infusion of gentamicin on characteristics of the synovial fluid. ANIMALS: 12 healthy adult horses. PROCEDURE: An infusion catheter consisting of flow control tubing connected to a balloon infuser was used. Gentamicin solution (100 mg/ml) was infused in the right tarsocrural joint and balanced electrolyte solution was infused in the left tarsocrural joint for 5 days. Synovial fluid and serum gentamicin concentrations were measured by use of a fluorescence polarization immunoassay. RESULTS: 17 of the 24 (71%) infusion catheters initially placed functioned without complications for the entire 5-day infusion period. Median gentamicin concentration in synovial fluid from treated joints during the 5-day infusion period ranged from 2875 to 982 microg/ml. Median serum gentamicin concentration during this period ranged from 2.31 to 2.59 microg/ml. Mean (+/- SD) elimination half-life and total clearance of gentamicin from the synovial fluid were 6.25+/-1.01 hours and 1.52+/-0.96 ml/min, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: An infusion catheter can be used for continuous infusion of gentamicin into the tarsocrural joints of horses for up to 5 days. At a gentamicin dosage of 0.17+/-0.02 mg/kg/h, continuous intra-articular infusion results in synovial fluid gentamicin concentrations greater than 100 times the minimal inhibitory concentration reported for common equine pathogens.

Animals↗

PubMed2000

10 years of experience with penile prosthesis implantation in Taiwanese patients.

PURPOSE: We evaluated the long-term results of penile prosthesis implantation during the last 10 years. Special considerations were examined concerning Asian corporeal diameter, device survival and sociocultural factors influencing patient-partner satisfaction. MATERIALS AND METHODS: We followed 331 patients who underwent penile prosthesis implantation from December 1985 to May 1996. Surgical data, postoperative complications and information from a survey on satisfaction are reported. RESULTS: The most prevalent corporeal diameter in our patients was 11.0 to 11.5 cm. Postoperatively wound infection was the most serious surgical complication. The 5-year device survival was similar in the malleable and inflatable types except for a poorer outcome with the self-contained inflatable Hydroflex penile prosthesis. Overall patient satisfaction with surgery was 86.6%. CONCLUSIONS: Penile prosthesis implantation still has its place as definitive therapy in some patients with uncorrectable erectile dysfunction. In Taiwanese society more consideration of prosthesis selection, surgical preparation and patient-partner counseling is the basis for further success in the future.

Actuarial Analysis↗

PubMed2000

Bone grafting techniques in treating fracture nonunion.

A fracture nonunion is not uncommon and the principle of treatment has been well established. Traditionally, for the efficacy of treatment, a nonunion is classified as a hypervascular (hypertrophic) or an avascular (atrophic) type. Methods for treating nonunion are multiple and bone grafting techniques have been the most convincing and widely used. Bone grafts can be divided into allografts and autografts and cortical or cancellous bone grafts; each has its individual function. However, both types of a nonunion need to be supplemented with cancellous bone graft to increase the rate of success. Basically, effective treatment should include making fracture gaps vanish, providing sufficient stability, and initiating osteogenic power. Clinically, use of the closed bone grafting technique is preferable when possible. However, the critical size for using the closed technique to treat segmental bony defects has yet to be defined, and the open technique should be utilized whenever the effectiveness of the closed technique is in doubt. To simplify the surgical procedure and to reduce morbidity at the donor site, bone graft substitutes should be continuously investigated.

Bone Transplantation↗

PubMed2000

Postoperative coma induced by hyponatremia after laparoscopy--a case report.

Hyponatremia is a common clinical entity which may occur during the course of many medical illnesses. However disastrous sequelae or even death may develop in young, generally healthy patients who receive simple elective surgery. Here we present a case of a 34-year-old female, without past history of cardiopulmonary or renal disease, after undergoing laparoscopic surgery developed mental status changes and lapsed into coma on the second postoperative day. She was found to have a serum sodium level of 110 mEq/L. After careful treatment and a protracted hospital stay, the patient recovered uneventfully. The pathophysiology of postoperative hyponatremia is discussed and attention is called to the special vulnerability of menstruant women who carry a much increased risk of mortality and morbidity associated with hyponatremia.

Adult↗

PubMed2000

Histopathologic analysis of sentinel lymph nodes in breast carcinoma.

BACKGROUND: Intraoperative lymphatic mapping and identification of the first draining lymph node (the sentinel lymph node) may allow some patients with breast cancer to avoid the morbidity of formal axillary clearance. The aim of this study was to determine the accuracy of sentinel lymph node (SLN) biopsy in predicting axillary nodal involvement. METHODS: From August, 1998 until July, 1999, 41 patients with clinically node-negative breast cancer underwent SLN biopsy that was immediately followed by axillary lymph node dissection. If the SLN section was found free of metastasis by routine hematoxylin and eosin staining (H&E), then an additional four sections of the SLN were cut and examined for the presence of tumor cells by H&E staining (three sections) and by cytokeratin immunohistochemical staining (IHC) (one section). If the SLN had metastatic cells and the other remaining nonsentinel axillary lymph nodes were free of metastases by routine H&E staining, then an additional three sections of the nonsentinel axillary lymph nodes were cut and examined for the presence of tumor cells by H&E staining. RESULTS: The 41 patients had a mean of 2.2 sentinel (range, 1-7) and 14.6 nonsentinel (range, 5-32) lymph nodes excised per patient. Routine H&E staining identified 13 patients (31.7%) with SLN metastases and 28 patients (68.3%) with tumor-free SLNs. Applying IHC and the additional three sections stained with H&E to these tumor-free SLNs showed one additional patient with sentinel node metastasis. The conversion rate from being a sentinel node-negative patient to a sentinel node-positive patient was 3.6% (1/28). Overall, SLN metastases were detected in 14 (34.1%) of the 41 patients. The SLNs were negative in 27 patients (65.9%), two of whom had at least one positive nonsentinel lymph node each (7.4% "skip" metastasis). Biopsy of SLNs was 92.6% accurate in predicting the absence of nonsentinel nodal metastasis (p=0.001). CONCLUSIONS: Our results suggest that formal axillary lymph node dissection may need only be performed in SLN-positive patients. Nonetheless, further experience and refinement are needed to perfect this technique.

Adult↗

PubMed2000

GMx33: a novel family of trans-Golgi proteins identified by proteomics.

The known functions of the Golgi complex include the sorting, packaging, post-translational modification, and transport of secretory proteins, membrane proteins, and lipids. Other functions still remain elusive to cell biologists. With the goal of identifying novel Golgi proteins, a proteomics project was undertaken to map the major proteins of the organelle using two-dimensional gels, to identify the unknowns using tandem mass spectrometry, and to screen for Golgi residents using GFP-fusion constructs. Multiple unknowns were identified, and the initial characterization of one of these proteins is reported here. GMx33 alpha is a member of a conserved family of cytosolic Golgi-associated proteins with no known homology to any known functional domain or protein. Biochemical analyses show that GMx33 alpha differentially partitions into all phases of multiple detergent extractions, and two-dimensional immunoblots reveal that there are multiple differentially modified forms of GMx33 alpha associated with the Golgi, several of which are phosphorylated. Evidence suggests that these post-translational modifications regulate its association with the Golgi. GMx33 alpha was not found on Golgi budded vesicles, and immuno-electron microscopy co-localizes GMx33 alpha to the trans-face on the same three cisternae as TGN38 in normal rat kidney cells. This work represents the preliminary characterization of a novel family of trans-Golgi-associated proteins.

Amino Acid Motifs↗

PubMed2000

Study of propofol in bovine aortic endothelium: I. Inhibitory effect on bradykinin-induced intracellular calcium immobilization.

BACKGROUND: Propofol has been found to affect the intracellular calcium concentration with clinical manifestations of hypotension and bradycardia. The purpose of this study is to examine the effect of propofol on intracellular calcium immobilization in bovine aortic endothelium under the stimulation of bradykinin. METHODS: In order to validate the effect of propofol on the alteration of intracellular calcium concentration, we used the cultured bovine endothelial cells (Gm 7372a) to measure the calcium immobilization within the cells preincubated with or without propofol of clinical concentration. Using Fluo-3 staining and a fluorescence spectrophotometer (confocal microscope), intracellular calcium immobilization was demonstrated by the appearance of "hot spots" within the cytoplasm and perinuclear regions after addition of bradykinin to the cells. The changes of fluorescence density measured within these areas versus the effect of time were analyzed and compared with the cells in control group. RESULTS: After addition of bradykinin, intracellular calcium hot spots increased dramatically within seconds and reached a maximal level within 20 seconds. The concentrations of calcium gradually decreased to a constant level after about 3 min following the addition of bradykinin to the cells. With pretreatment of propofol at 0.01 mM and 37 degrees C for 30 min, the immobilization of intracellular calcium from the intracellular stores were significantly inhibited that was demonstrated by the decreased appearance of hot spots when compared with control. CONCLUSIONS: Our data demonstrated that under the stimulation of bradykinin, propofol at 0.01 mM, could inhibit intracellular calcium release from the intracellular stores in bovine aortic endothelial cells. This phenomenon might explain the possible mechanism for the clinical manifestations of hypotension and/or bradycardia associated with propofol.

Anesthetics, Intravenous↗

PubMed1999

Comparison between effects of dantrolene and nifedipine on lipopolysaccharide-induced endotoxemia in the anesthetized rats.

Intracellular calcium is an important mediator for regulating the cellular response in endotoxemia. In this study, we investigated the effects of dantrolene and nifedipine, two agents of reducing intracellular calcium levels, on bacterial endotoxin (lipopolysaccharide, LPS; 10 mg/kg i.v.)-induced production of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) as well as hemodynamic changes in the anesthetized rat. Injection of LPS (i) induced biphasic changes of blood glucose and rectal temperature: an initial increased phase (<180 min after injection of LPS) followed by a decreased phase (at 240 or 360 min), (ii) caused a significant fall in mean arterial blood pressure from 119+/-3 mmHg (at time 0) to 73+/-67 mmHg (at 360 min) with a concomitant increase of heart rate, (iii) resulted in a substantial hyporeactivity to norepinephrine (NE) (1 microg/kg i.v.), (iv) increased plasma nitrate (an indicator of NO formation) in a time-dependent manner, and (v) induced bell-shape changes in plasma TNF-alpha levels which reached a peak at 60 min. Pretreatment of animals with dantrolene (1 mg/kg i.v. at 20 min prior to LPS) or nifedipine (20 microg/kg i.v. infusion for 20 min at 20 min prior to LPS) not only attenuated the delayed circulatory failure (e.g. delayed hypotension and vascular hyporeactivity to NE), but also prevented the overproduction of NO caused by LPS in the rat. However, the prevention of NO overproduction by dantrolene, but not by nifedipine, was associated with an inhibition of TNF-alpha production elicited by LPS. Thus, both dantrolene and nifedipine have beneficial hemodynamic effects, although through different mechanisms, in animals with endotoxic shock.

Anesthesia↗

PubMed1999

Immune response of neonatal specific pathogen-free cats to experimental infection with Bartonella henselae.

The purpose of this study was to determine whether neonatal cats develop and maintain a persistent bacteremia for longer than do adult cats with a normal mature immune system, and whether neonatal cats are susceptible to infection with Bartonella henselae by oral inoculation. Neonatal specific pathogen-free (SPF) cats were inoculated with B. henselae intradermally (n = 4) or orally (n = 5) or with 0.9% NaCl (n = 2). Blood was collected periodically through 16 weeks post-inoculation (PI) for serology, bacteriology and complete blood count. Cats inoculated orally or intradermally at 3-5 days of age were bacteremic through 12-16 weeks PI, similar to what is documented for adult cats inoculated intradermally or intravenously. One cat inoculated at age 2 weeks was bacteremic through 10 weeks PI; the other was not bacteremic. Intradermally inoculated neonatal cats produced serum IgG antibodies to B. henselae but orally inoculated neonatal cats did not. Infected cats with and without serum IgG antibodies to B. henselae became blood-culture negative simultaneously, suggesting that IgG is not required to clear bacteremia.

Animals↗

PubMed1999

YC-1 potentiates the antiplatelet effect of hydrogen peroxide via sensitization of soluble guanylate cyclase.

In the present study, we showed that 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1), a nitric oxide (NO)-independent activator of soluble guanylate cyclase, could potentiate H2O2-induced inhibition of platelet aggregation and increase of platelet cGMP levels. The synergistic effect of YC-1 and H2O2 on platelet aggregation and increases of cGMP were almost completely prevented by catalase and a selective soluble guanylate cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), or partially attenuated by the hydroxyl radical scavenger mannitol. In contrast, superoxide dismutase failed to influence H2O2/YC-1-induced inhibition of aggregation. Furthermore, YC-1 could enhance the activation of soluble guanylate cyclase caused by FeSO4/H2O2 and, this effect was prevented markedly by mannitol. These results suggest that YC-1 may enhance the antiaggregatory effect of H2O2 via the sensitization of platelet soluble guanylate cyclase. In addition, this phenomenon is, at least in part, dependent on H2O2-derived hydroxyl radical.

Antioxidants↗

PubMed1999

Significance of dobutamine-induced ST-segment evaluation and T-wave pseudonormalization in patients with Q-wave myocardial infarction: simultaneous evaluation by dobutamine stress echocardiography and thallium-201 SPECT.

The clinical significance of stress-induced ST-segment elevation and T-wave pseudonormalization in infarct-related leads is still controversial. Therefore, we conducted the present study to assess this issue using simultaneous dobutamine stress echocardiography (DSE) and thallium-201 single-photon emission computed tomography. A total of 119 patients with Q-wave myocardial infarction were enrolled in this study. There were 58 patients with (group I) and 61 patients without (group II) dobutamine-induced ST-T changes. Left ventricular ejection fraction was 43 +/- 13% in group I and 49 +/- 14% in group II (p <0.05). The baseline, low-, and peak-dose global wall motion scores were similar between these 2 groups (26.2 +/- 6.1 vs 26.2 +/- 6.3 [p = NS]; 24.1 +/- 5.3 vs 23.5 +/- 5.7 [p = NS]; 26.4 +/- 5.7 vs 26.7 +/- 6.1 [p = NS]). The sensitivity, specificity, and accuracy of these ST-T changes for detecting residual myocardial viability and ischemia documented by DSE in all patients were 50%, 53%, and 51% (for viability), and 47%, 48%, and 47% (for ischemia), respectively. The sensitivity, specificity, and accuracy of these ST-T changes for detecting a reversible perfusion defect documented by thallium-201 single-photon emission computed tomography were 51%, 54%, and 52%, respectively. In conclusion, dobutamine-induced ST elevation and/or T-wave pseudonormalization is associated with poor resting left ventricular function. These ST-T changes are not associated with residual myocardial ischemia and viability in the infarct area. Therefore, these electrocardiographic changes alone cannot be reliably considered as distinctive markers in formulating the therapeutic strategy of coronary intervention.

Cardiotonic Agents↗

PubMed1999

Pentoxifylline improves circulatory failure and survival in murine models of endotoxaemia.

Pentoxifylline, a methylxanthine derivative, has been widely used to improve erythrocyte deformability and capillary blood circulation in patients with claudication and cerebrovascular disorders as well as in animals with sepsis. Here, we investigate the effects of pentoxifylline on the hypotension, vascular hyporeactivity to noradrenaline, release of tumour necrosis factor-alpha (TNF-alpha) and nitric oxide (NO), and inducible NO synthase protein expression in a rat model of circulatory shock induced by bacterial endotoxin (Escherichia coli lipopolysaccharide). In addition, we have evaluated the effect of pentoxifylline on the 36-h survival rate in a murine model of endotoxaemia. Male Wistar-Kyoto rats were anaesthetised and instrumented for the measurement of mean arterial pressure and heart rate. Injection of lipopolysaccharide (10 mg/kg, i.v.) resulted in a significant fall in mean arterial pressure and an increase of heart rate. In contrast, animals pretreated with pentoxifylline (3 mg/kg, i.v., at 30 min prior to lipopolysaccharide) maintained a significantly higher mean arterial pressure but showed no effect on the tachycardia when compared to rats given only lipopolysaccharide (lipopolysaccharide-rats). The pressor effect of noradrenaline (1 microg/kg, i.v.) was also significantly reduced after the treatment of rats with lipopolysaccharide. Similarly, rings of thoracic aorta obtained from lipopolysaccharide-rats showed a significant reduction in the contractile responses elicited by noradrenaline (1 microM). Pretreatment of lipopolysaccharide-rats with pentoxifylline partially, but significantly, prevented this lipopolysaccharide-induced hyporeactivity to noradrenaline in vivo and ex vivo. The injection of lipopolysaccharide resulted in bell-shape changes in plasma TNF-alpha level which reached a peak at 60 min, whereas the effect of lipopolysaccharide on the plasma level of nitrate (an indicator of NO formation) was increased in a time-dependent manner. This increase of both TNF-alpha and nitrate levels induced by lipopolysaccharide was significantly reduced in lipopolysaccharide-rats pretreated with pentoxifylline. Endotoxaemia for 240 min caused a significantly increased protein expression of inducible NO synthase in the lung. In lipopolysaccharide-rats pretreated with pentoxifylline, inducible NO synthase protein expression in lung homogenates was attenuated by 48 +/- 5%. Treatment of conscious mice with a high dose of endotoxin (60 mg/kg, i.p.) resulted in a survival rate of only 10% at 36 h (n = 20). However, therapeutic application of pentoxifylline (3 mg/kg, i.p. at 0, 6, 15 and 24 h after lipopolysaccharide) increased the 36-h survival to 35% (n = 20). Thus, pentoxifylline protects against circulatory failure and improves survival in rodents with severe endotoxaemia. These effects may be due to inhibition of the release of TNF-alpha and of the induction of inducible NO synthase.

Anesthesia↗

PubMed1999

NF-kappa B-dependent Fas ligand expression.

Apoptosis of lymphocytes is triggered by different stimuli through the induced expression of Fas and Fas ligand (FasL). Using T cell activation-induced Fas/FasL expression as a model system, we observed a differential regulation of the induction of Fas and FasL. cAMP inhibited activation-induced apoptosis by an effective suppression of TCR-coupled FasL expres sion. In contrast, cAMP weakly interfered with activation-induced Fas expression, and the remaining Fas molecules on cAMP-treated T cells still mediated apoptosis. Among the major transcription elements on the FasL promoter, the activation of NF-kappaB, but not of NF-AT and AP-1, was suppressed by cAMP. The prominent role of NF-kappaB was further demonstrated by a better activation of the FasL promoter and an elevated expression of FasL induced by p65 (RelA) overexpression than those induced by AP-1 or NF-AT. Our results demonstrate the essential role of NF-kappaB for the expression of the death receptor ligand FasL, and suggest a direct link between NF-kappaB activation and the expression of FasL. NF-kappaB may be the common mediator in the induction of FasL through TCR activation and by various stress stimuli.

Antibodies, Monoclonal↗

PubMed1999

Low-intensity ultrasound stimulates proteoglycan synthesis in rat chondrocytes by increasing aggrecan gene expression.

We evaluated the effect of low intensity-pulsed ultrasound stimulation on rat chondrocytes in vitro using two different 1.0-MHz ultrasound signals with spatial and temporal average intensities of 50 or 120 mW/cm2. The pulses had a duration of 200 microseconds and were repeated every millisecond, with corresponding average peak-pressure amplitudes of 230 or 360 kPa, respectively. Cells were stimulated one, three, or five times for 10 minutes each day starting the third day after plating. One group of cells was exposed to sham ultrasound as a control. The cultures were evaluated for cell proliferation (by [3H]thymidine incorporation and DNA measurement), steady-state mRNA levels of alpha1(I) and alpha1(II) procollagens and aggrecan (by Northern blotting), and proteoglycan synthesis (by [35S]sulfate incorporation). The results revealed that ultrasound causes increases in the level of aggrecan mRNA (p < 0.05) and in proteoglycan synthesis (p < 0.03) after three and five treatments. Expression of mRNA for alpha1(II) procollagen increased over time, but ultrasound had no stimulatory effect. Expression of mRNA for alpha1(I) procollagen was initially low and remained unchanged with time. Although cell proliferation increased with time in both groups, there was no statistically significant difference between the cultures treated with ultrasound and the controls (p = 0.1). The in vitro results support our previous in vivo findings that low-intensity ultrasound stimulates aggrecan mRNA expression and proteoglycan synthesis by chondrocytes, which may explain the role of ultrasound in advancing endochondral ossification, increasing the mechanical strength of fractures, and facilitating fracture repair.

Aggrecans↗