Chronic Kidney Disease, But Not Diabetes, Can Predict 30-Day Outcomes in Patients with ST-Elevation Myocardial Infarction after Primary Percutaneous Coronary Intervention: A Single-Center Experience

BACKGROUND

Patients with acute coronary syndrome and impaired renal function have been shown to have high mortality. However, there is scarce literature to date addressing the impact of diabetes mellitus (DM) and renal function on clinical outcomes of ST elevation myocardial infarction (STEMI) in Taiwan.

METHOD

This study enrolled 512 STEMI patients who received primary percutaneous coronary intervention. Patients were divided into 4 groups including group 1: patients without DM or CKD (nDM-nCKD); group 2: patients with DM but without CKD (DM-nCKD); group 3: patients with CKD but without DM (nDM-CKD); group 4: patients with DM and CKD (DM-CKD). Patients were also classified into four groups based on their estimated glomerular filtration rates (eGFR): stage 1 (eGFR ≥ 90 ml/min/1.73 m(2), n = 163), stage 2 (eGFR = 89-60 ml/min/1.73 m(2), n = 171), stage 3 (eGFR = 59-30 ml/min/1.73 m(2), n = 136), and stage 4 (eGFR < 30 ml/min/1.73 m(2), n = 42). The complication rates, length of hospital stay, and 30-day outcomes were analyzed.

RESULTS

The patients in both the nDM-CKD group and DM-CKD group had higher incidences of hypotension, intra-aortic balloon counterpulsation use, and respiratory failure (p < 0.005). They had significantly longer hospital stay and 30-day mortality rates (p < 0.001). The patients with CKD stage 3 and 4 had longer hospital stay and higher 30-day mortality rates (p < 0.001). However, DM was not an independent factor on the length of hospital stay and 30-day mortality rates.

CONCLUSIONS

STEMI patients with impaired renal function, but not DM, had significantly longer hospital stay and higher 30-day mortality rates.

KEY WORDS

Chronic kidney disease; Diabetes mellitus; Mortality; Primary percutaneous coronary intervention; ST-segment elevation myocardial infarction.

The Effect of Intensified Low Density Lipoprotein Cholesterol Reduction on Recurrent Myocardial Infarction and Cardiovascular Mortality

BACKGROUND

Lipid-lowering therapy plays an important role in preventing the recurrence of cardiovascular events in patients after acute myocardial infarction (AMI). This study aimed to assess the effect of intensified low density lipoprotein cholesterol (LDL-C) reduction on recurrent myocardial infarction and cardiovascular mortality in patients after AMI.

METHOD

The 562 enrolled AMI patients (84.2% male) were divided into two groups according to 3-month LDL-C decrease percentage equal to or more than 40% (n = 165) and less than 40% (n = 397). To evaluate the long-term efficacy of LDL-C reduction, the 5-year outcomes were collected, including time to the first occurrence of myocardial infarction and time to cardiovascular death.

RESULTS

The baseline characteristics and complication rates were not different between the two study groups. The patients with 3-month LDL-C decrease ≥ 40% had higher baseline LDL-C and lower 3-month, 1-year, 2-year, 3-year, 4-year and 5-year LDL-C than the patients with 3-month LDL-C decrease < 40%. In Kaplan-Meier analyses, those patients with 3-month LDL-C decrease ≥ 40% had a higher rate of freedom from myocardial infarction (p = 0.006) and survival rate (p = 0.02) at 5-year follow-up. The 3-month LDL-C < 40% parameter was significantly related to cardiovascular death (HR: 9.62, 95% CI 1.18-78.62, p < 0.04).

CONCLUSIONS

After acute myocardial infarction, 3-month LDL-C decrease < 40% was identified to be a significant risk factor for predicting 5-year cardiovascular death. The patients with 3-month LDL-C decrease ≥ 40% had a higher rate of freedom from myocardial infarction and lower cardiovascular mortality, even though these patients had higher baseline LDL-C value.

KEY WORDS

Acute myocardial infarction; Cardiovascular death; Low-density lipoprotein cholesterol; Mortality; Statin.

Five-Year Outcomes after Acute Myocardial Infarction in Patients with and without Diabetes Mellitus in Taiwan, 1996-2005

BACKGROUND

Diabetes mellitus (DM) is a strong risk factor of cardiovascular disease. To date, the impact of DM on outcomes after acute myocardial infarction (AMI) in Taiwan is undetermined. The aim of this study was to compare five-year outcomes after AMI in patients with and without diabetes in Taiwan.

METHODS

A nationwide cohort of 25,028 diabetic and 56,028 non-diabetic patients who were first hospitalized with AMI between 1996 and 2005 was enrolled through linkage with the Taiwan National Health Insurance research database. Patient mortality rates within 30 days after AMI, and 1, 3, and 5 years thereafter were compared.

RESULTS

Length of hospital stay (8.9 ± 8.7 vs. 8.2 ± 8.0 days, p < 0.01) and medical cost during admission (in Taiwan dollars: $129,123 ± $158,073 vs. $121,631 ± $157,018, p < 0.01) were significantly higher in diabetic patients. The difference in mortality rate within 30 days was insignificant between diabetic and non-diabetic patients (18.1% vs. 17.6%, p = 0.06). Mortalities within 1 year (31.0% vs. 26.8%, p < 0.01), 3 years (42.4% vs. 34.7%, p < 0.01), and 5 years (50.6% vs. 41.1%, p < 0.01) were significantly higher in diabetic patients. In patients with AMI who underwent percutaneous coronary intervention (PCI) during index admission, the mortality rate within 30 days was insignificant (6.3% vs. 6.4%, p = 0.70) but mortalities within 1 year (15.2% vs. 11.6%, p < 0.01), 3 years (24.1% vs. 17.2%, p < 0.01), and 5 years (32.2% vs. 22.6%, p < 0.01) were significantly higher in diabetic patients.

CONCLUSIONS

The average patient length of hospital stay and medical cost during admission were significantly higher in diabetic patients. Additionally, the difference in mortality rate within 30 days after AMI was insignificant between diabetic and non-diabetic patients. Also, long-term mortality after AMI was significantly higher in diabetic patients.

KEY WORDS

Acute myocardial infarction; Diabetes mellitus; Length of hospital stay; Medical cost; Mortality; National health insurance.

Body Mass Index and Outcome of Acute Myocardial Infarction - Is There an Obesity Paradox?

BACKGROUND

Although there have been some studies focusing on the relationship between body mass index (BMI), coronary artery disease (CAD) and acute coronary syndrome, the clinical effects of BMI on outcomes after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI) are not well known in a Taiwanese population.

METHODS

From January 2005 to December 2011, 1298 AMI patients who received PCI were enrolled from a single center in Taiwan. The patients were divided into 4 groups according to their BMI: underweight (BMI < 18.5 kg/m(2)); normal weight (18.5 ≤ BMI < 24 kg/m(2)); overweight (24 ≤ BMI < 27 kg/m(2)) and obese (BMI ≥ 27). All patients had been followed up for at least 12 months, and 30-day and 5-year all-cause and cardiovascular-cause mortality were compared among the study groups.

RESULTS

The patients in the underweight group had a lower 30-day survival rate than the other 3 groups, and the underweight and normal weight patients had a lower 5-year survival rate than the overweight and obese patients. The multivariate regression analysis showed that Killip class ≥ 2, non-use of statin, older age, hemoglobin < 12 g/dl and chronic kidney disease, but not BMI, are independent predictors of all-cause mortality.

CONCLUSIONS

In this present study, the major factors affecting long-term survival are lack of using statin and older age, but not obese paradox.

KEY WORDS

Acute myocardial infarction; Mortality; Obesity; Percutaneous coronary intervention; Survival.

The effect of failure mode and effect analysis on reducing percutaneous coronary intervention hospital door-to-balloon time and mortality in ST segment elevation myocardial infarction

BACKGROUND

Door-to-balloon (D2B) time is an important factor in the outcome of ST segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention. We aimed to use failure mode and effect analysis to reduce the D2B time for patients with STEMI and to improve clinical outcomes.

METHODS

There were three stages in this study. In Stage 0, data collected from 2005-2006 was used to identify failures in the process, and during Stage 2 (2007) and Stage 3 (2008) the efficacy of intrahospital and interhospital strategies to reduce the D2B time were evaluated. This study enrolled 385 patients; 86 from 2005-2006; 80 in 2007; and 219 in 2008.

RESULTS

By making improvements in these steps, the median D2B time was reduced from 146 min to 32 min for all patients. The proportion of patients with a D2B time of <90 min significantly increased from Stage 0 to Stage 1 and from Stage 1 to Stage 2, for all patients as well as for the non-transferred and transferred subgroups of patients (all p values <0.0001). For non-transferred patients, only reinfarction-free survival showed significant difference among the three stages (p=0.0225), and for transferred patients, only overall survival showed significant difference among the three stages (p=0.0322). Cox's proportional hazards regression analysis showed Stage 2 was associated with a lower risk of reinfarction and mortality compared with Stage 0.

CONCLUSIONS

This study found that failure mode and effect analysis is a powerful method for identifying weaknesses in D2B processes and evaluating strategies to reduce the D2B time.

Comparing radiation exposure during percutaneous vertebroplasty using one- vs. two-fluoroscopic technique

Background

Percutaneous vertebroplasty (PV) requires relatively lengthy fluoroscopic guidance, which might lead to substantial radiation exposure to patients or operators. The two-fluoroscopic technique (two-plane radiographs obtained using two fluoroscopes) during PV can provide simultaneous two-planar projections with reducing operative time. However, the two-fluoroscopic technique may expose the operator or patient to increased radiation dose. The aim of this study was to quantify the amount of radiation exposure to the patient or operator that occurs during PV using one- vs. two-fluoroscopic technique.

Methods

Two radiation dosimeters were placed on the right flank of each patient and on the upper sternum of each operator during 26 single-level PV procedures by one senior surgeon. The use of two-fluoroscopic technique (13 patients) and one-fluoroscopic technique (13 patients) were allocated in a consecutive and alternative manner. The operative time and mean radiation dose to each patient and operator were monitored and compared between groups.

Results

Mean radiation dose to the patient was 1.97 ± 1.20 mSv (95% CI, 0.71 to 3.23) for the one-fluoroscopic technique group vs. 0.95 ± 0.34 mSv (95% CI, 0.85 to 1.23) for the two-fluoroscopic technique group (P =0.031). Mean radiation dose to the operator was 0.27 ± 0.12 mSv (95% CI, 0.17–0.56) for the one-fluoroscopic technique group vs. 0.25 ± 0.14 mSv (95% CI, 0.06–0.44) for the two-fluoroscopic technique group (P = 0.653). The operative time was significantly different between groups: 47.15 ± 13.48 min (range, 20–75) for the one-fluoroscopic technique group vs. 36.62 ± 8.42 min (range, 21–50) for the two-fluoroscopic technique group (P =0.019).

Conclusion

Compared to the one-fluoroscopic technique, the two-fluoroscopic technique used during PV provides not only shorter operative times but also reduces the radiation exposure to the patient. There was no significant difference between the two techniques with regards to radiation exposure to the operator.

Left atrial distensibility and E/e' for estimating left ventricular filling pressure in patients with stable angina. -A comparative echocardiography and catheterization study-

BACKGROUND

Although E/e' (the ratio of early diastolic mitral inflow velocity to early diastolic mitral annular velocity) is widely used to measure left ventricular filling pressure (LVFP), its accuracy is questionable in coronary artery disease patients.

METHODS AND RESULTS

Echocardiograms and LVFP were obtained from 174 patients with stable angina (Canadian Cardiovascular Society angina grade I-II) who had received interventions for angiography-confirmed coronary stenosis. Compared with single-vessel groups, the multiple-vessel group exhibited lower mitral annular velocities, higher LVFP, and stronger correlations between E/regional e' and LVFP. Additionally, stronger correlations between E/regional e' and LVFP existed in patients with systolic dysfunction or lower variation of myocardial performance index (MPI) among anterior, inferior and lateral borders of mitral annulus. Average e' was not superior to any regional e' for assessing LVFP by the E/e' method. E/e' and left atrial (LA) ejection fraction (EF) correlated linearly with LVFP, but the correlation between LA distensibility and LVFP was logarithmical. Compared with E/e', LA distensibility and LAEF were superior for identifying high LVFP.

CONCLUSIONS

E/e' is not completely satisfactory for assessing LVFP in patients with stable angina, especially those with single-vessel disease, preserved systolic function or high MPI variation. For identifying high LVFP, LA distensibility and LAEF are better than E/e'.

Left atrial parameters in the estimation of left ventricular filling pressure and prognosis in patients with acute coronary syndrome

Because left atrial (LA) volume plays a critical role in determining cardiovascular outcomes, it was hypothesized that this might be related to the distensibility of the left atrium and how this relates to left ventricular filling pressure (LVFP). Echocardiographic estimates of LVFP were compared to cardiac catheterization measurements in 521 consecutive patients with acute myocardial infarction and correlated with short- and long-term outcomes. Receiver-operating characteristic curve analysis was performed to investigate the sensitivity and specificity of echocardiographic parameters for predicting elevated LVFP (> 15 mm Hg). LA distensibility was calculated as (maximal volume - minimal volume) × 100%/minimal volume(.) and was found to be logarithmically associated with LVFP (p < 0.0001). LA distensibility was superior to mitral E/annular Em for identifying increased LVFP (area under the receiver-operating characteristic curve 0.92 vs 0.78). A total of 44 patients died during hospitalization, and 89 patients had died or experienced heart failure requiring rehospitalization at 12-month follow-up. In a multivariate Cox regression model, LA distensibility was an independent predictor of in-hospital mortality (hazard ratio 2.373 for LA distensibility ≤ 60%, p = 0.026), while LA volume was an independent prognostic factor of 1-year death or heart failure (hazard ratio 2.266 for LA volume ≥ 34 ml/m², p = 0.007). In conclusion, LA distensibility accurately identifies patients with increased LVFP after acute myocardial infarction and is an independent predictor of in-hospital mortality.

Role of the supine lateral radiograph of the spine in vertebroplasty for osteoporotic vertebral compression fracture: a prospective study

Background

Severely collapsed vertebral compression fracture (VCF) is usually considered as a contraindication for vertebroplasty because of critically decreased vertebral height (less than one-third the original height). However, osteoporotic VCF can possess dynamic mobility with intravertebral cleft (IVC), which can be demonstrated on supine lateral radiographs (SuLR) and standing lateral radiographs (StLR). The purposes of this study were to: (1) evaluate the efficacy of SuLR to detect IVCs and assess the intravertebral mobility in VCFs, and (2) evaluate the short-term results of vertebroplasty in severely collapsed VCFs with IVCs.

Methods

We enrolled 37 patients with 40 symptomatic osteoporotic VCFs for vertebroplasty; 11 had severely collapsed VCFs with concurrent IVCs detected on the SuLR, the others had not-severely collapsed VCFs. A preoperative StLR, SuLR, magnetic resonance imaging (MRI), and postoperative StLR were taken from all patients. Radiographs were digitized to calculate vertebral body morphometrics including vertebral height ratio and Cobb's kyphotic angle. The intensity of the patient's pain was assessed by the visual analogue scale (VAS) on the day before operation and 1 day, 1 month, and 4 months after operation. The patient's VAS scores and image measurement results were assessed with the paired t-test and Pearson correlation tests; Mann-Whitney U test was used for VAS subgroup comparison. Significance was defined as p < 0.05.

Results

IVCs in patients with not-severely collapsed VCFs were detected in 21 vertebrae (72.4%) by MRI, in 15 vertebrae (51.7%) by preoperative SuLR, and in 7 vertebrae (24.1%) by preoperative StLR. Using the MRI as a gold standard to detect IVCs, SuLR exhibit a sensitivity of 0.71 as compared to StLR that yield a sensitivity of 0.33. In patients with VCFs with IVCs detected on SuLR, the average of the postoperative restoration in vertebral height ratio was significantly higher than that in those without IVCs (17.1% vs. 6.4%). There was no statistical difference in the VAS score between severely collapsed VCFs with IVCs detected on SuLR and not-severely collapsed VCFs at any follow-up time point.

Conclusions

The SuLR efficiently detects an IVC in VCF, which indicates a better vertebral height correction after vertebroplasty compared to VCF without IVC. Before performing a costly MRI, SuLR can identify more IVCs than StLR in patients with severely collapsed VCFs, whom may become the candidates for vertebroplasty.

Management of giant pseudomeningoceles after spinal surgery

Background

Pseudomeningoceles are a rare complication after spinal surgery, and studies on these complex formations are few.

Methods

Between October 2000 and March 2008, 11 patients who developed symptomatic pseudomeningoceles after spinal surgery were recruited. In this retrospective study, we reported our experiences in the management of these complex, symptomatic pseudomeningoceles after spinal surgery. A giant pseudomeningocele was defined as a pseudomeningocele >8 cm in length. We also evaluated the risk factors for the formation of giant pseudomeningoceles.

Results

All patients were treated successfully with a combined treatment protocol of open revision surgery for extirpation of the pseudomeningoceles, repair of dural tears, and implantation of a subarachnoid catheter for drainage. Surgery-related complications were not observed. Recurrence of pseudomeningocele was not observed for any patient at a mean follow-up of 16.5 months. This result was confirmed by magnetic resonance imaging.

Conclusions

We conclude that a combined treatment protocol involving open revision surgery for extirpation of pseudomeningoceles, repair of dural tears, and implantation of a subarachnoid catheter for drainage is safe and effective to treat giant pseudomeningoceles.

Left atrial distensibility and left ventricular filling pressure in acute versus chronic severe mitral regurgitation

Echocardiograms and left ventricular (LV) filling pressure were obtained from 95 patients with chronic severe mitral regurgitation (MR) and 16 patients with acute severe MR. All patients underwent catheterization for preoperative examinations and LV filling pressure measurements. A total of 52 age-, gender- and co-morbidity-matched patients with negative coronary angiographic results served as the controls. Echocardiography, including assessment of left atrial (LA) distensibility, was performed simultaneously. LA distensibility correlated logarithmically with the LV filling pressure. However, the early-diastolic mitral inflow velocity divided by the early-diastolic mitral annular velocity (mitral E/E') correlated linearly with the LV filling pressure. Bivariate correlation analysis revealed that LV filling pressure correlated positively with the maximum and minimum indexed LA volume, as well as the E/E', but the LV filling pressure correlated negatively with LA distensibility, LA ejection fraction, and LV ejection fraction. However, the MR regurgitation volume was associated only with the maximum and minimum indexed LA volume. Receiver operating characteristic curve analysis indicated that LA distensibility was not inferior to E/E' for identifying a LV filling pressure >15 mm Hg. However, to identify acute severe MR, LA distensibility was superior to E/E'. In conclusion, LA distensibility, as is E/E', is a valuable diastolic parameter. In patients with severe MR, it offers adequate power to assess the LV filling pressure and to identify acute severe MR.

PI3K/AKT regulates aggrecan gene expression by modulating Sox9 expression and activity in nucleus pulposus cells of the intervertebral disc

The goal of the investigation was to test the hypothesis that the phosphoinositide-3 kinase (PI3K)/AKT signaling pathway regulates the expression of the major extracellular matrix component of the intervertebral disc, aggrecan, in nucleus pulposus cells. Primary rat nucleus pulposus cells were treated with PI3K inhibitor to measure changes in gene and protein expression. In addition, cells were transfected with various luciferase reporter plasmids to investigate mechanisms of regulation of aggrecan gene expression. We found that treatment of nucleus pulposus cells with a PI3K inhibitor, LY294002 resulted in decreased expression of aggrecan and a reduction in deposition of sulfated glycosaminoglycans. Moreover, pharmacological suppression or co-expression of dominant negative (DN)-PI3K or DN-AKT resulted in downregulation of aggrecan promoter activity. Expression of constitutively active (CA)-PI3K significantly induced aggrecan promoter activity. We observed that PI3K maintained Sox9 gene expression and activity: inhibition of PI3K/AKT resulted in decreased Sox9 expression, lowered promoter activity, and mediated a reduction in Sox9 transcriptional activity. PI3K effects were independent of phosphorylation status of C-terminus transactivation domain (TAD) of Sox9. Finally, we noted that in nucleus pulposus cells, PI3K signaling controlled transactivation of p300 (p300-TAD activity), an important transcriptional co-activator of Sox9. Results of these studies demonstrate for the first time that PI3K/AKT signaling controls aggrecan gene expression, in part by modulating Sox9 expression and activity in cells of the nucleus pulposus.

Minimally invasive vertebroplasty managed by a two C‐arm fluoroscopic technique

One C-arm fluoroscope is widely considered to be sufficient for effectively monitoring minimally invasive vertebroplasty. However, rotating the C-arm fluoroscope for different radiographic views of the spine can be time-consuming, causing delay in detecting cement leakage. We retrospectively reviewed the results of minimally invasive vertebroplasty utilizing two C-arm fluoroscopes in the treatment of osteoporotic vertebral fractures. Forty-two patients (50 vertebrae) were treated with minimally invasive vertebroplasty under the guidance of two C-arm fluoroscopes. The mean operation time, patient satisfaction rate and the incidences of cement leakage or infection were used to evaluate the feasibility and efficacy of the two C-arm fluoroscopic technique in performing minimally invasive vertebroplasty. The mean follow-up duration was 17.4 months (range 6 approximately 36). The mean operation time was 37+/-14 minutes. Thirty patients (71%) were very satisfied or satisfied with the procedure. Cement leakages were identified in nine patients (nine vertebrae, 18%). Only one vertebra had a posterior leakage into spinal canal, which did not cause neurologic deficits. No wound infection was observed. This study indicates that the two C-arm fluoroscopic technique provides simultaneous antero-posterior and lateral radiographic views, and therefore may reduce the operation time. No symptomatic cement leakage or wound infection was noted in this investigation. Moreover, no additional staff is needed to rotate the C-arm for fluoroscopy. The proposed technique has been shown to be effective and useful for performing minimally invasive vertebroplasty.

Actin-free Gc-globulin after minimal access and conventional anterior lumbar surgery

BACKGROUND

Minimally invasive total knee or hip replacement has been increasingly adopted in recent years. However, literature indicates that minimally invasive joint arthroplasty may not always reduce pain or tissue trauma. We hypothesized that the tissue damage would be reduced in minimal access surgery (MAS) than the conventional open surgery (OS) for anterior lumbar disorders through quantifying measurement of serum actin-free Gc-globulin (Af-Gc), myoglobin (MG), and total creatine kinase (CK).

MATERIALS AND METHODS

This prospective study enrolled 23 patients, including 10 who underwent MAS and thirteen who underwent conventional OS. Blood samples for Af-Gc, MG, and CK were taken simultaneously before surgery and then at intervals of 12, 24, 48, 72, 120, and 168 h thereafter.

RESULTS

All serum level changes in Af-Gc, MG, and CK were significantly lower in the MAS than in the OS group. A significant negative correlation was noted between changes in Af-Gc and MG levels (P = 0.012), and a significant positive correlation was noted between changes in CK and MG levels (P < 0.001). However, at 12 h postop, CK level was transiently higher in MAS group than the OS group.

CONCLUSIONS

The changes of Af-Gc, MG, and CK levels indicate that MAS is less tissue invasive than OS. Further, Af-Gc proved to be a more sensitive marker than MG or CK in response to surgical trauma. The transiently higher CK level at 12 h postop in MAS patients may indicate that a more soft tissue manipulation is required in MAS than the OS patients for the initial surgical approach.

A comparison between one- and two-fluoroscopic techniques in percutaneous vertebroplasty

BACKGROUND

Percutaneous vertebroplasty (PV) is generally performed under fluoroscopic guidance. Technically, single fluoroscope is considered sufficient for effectively monitoring PV. However, single fluoroscopic technique might be time-consuming in rotating the C-arm of the fluoroscope for either antero-posterior (AP) or lateral radiographic view, and causing delay in detecting cement leakage that can occur if the correct sight is not given. The aim of the current investigation was to compare the efficacy and safety of performing PV using one or two sets of fluoroscope.

METHODS

This retrospective study enrolled 43 patients with painful osteoporotic vertebral fractures and they were treated with one-level PV. A single orthopaedic surgeon operated on all these patients. The patients were divided into two groups on the basis of the method of fluoroscopic control. In Group 1 (15 patients), PV was performed under the assistance of one fluoroscope. In Group 2 (28 patients), PV was performed under the control of two fluoroscopes. The mean follow-up was 19 months (range, 12 to 30).

RESULTS

Neither symptomatic cement leakage nor postoperative infection was found in both groups. The mean operation time in Group 2 was shorter, 37.8 vs. 31.0 minutes for Groups 1 and 2, P = 0.03. The incidence of cement leakage for Groups 1 and 2 was 26.7% (4/15) vs. 14.3% (4/28), respectively, P = 0.19.

CONCLUSION

We found that the two-fluoroscopic technique can provide simultaneous, real-time AP and lateral radiographic views to monitor entry point and cement delivery for PV and therefore reduce the operation time. The two-fluoroscopic technique did not require a complex manpower organization and has been proved to be a safe and effective technique for PV.

Expression of acid-sensing ion channel 3 (ASIC3) in nucleus pulposus cells of the intervertebral disc is regulated by p75NTR and ERK signaling

Although a recent study has shown that skeletal tissues express ASICs, their function is unknown. We show that intervertebral disc cells express ASIC3; moreover, expression is uniquely regulated and needed for survival in a low pH and hypoeromsotic medium. These findings suggest that ASIC3 may adapt disc cells to their hydrodynamically stressed microenvironment.

INTRODUCTION

The nucleus pulposus is an avascular, hydrated tissue that permits the intervertebral disc to resist compressive loads to the spine. Because the tissue is hyperosmotic and avascular, the pH of the nucleus pulposus is low. To determine the mechanisms by which the disc cells accommodate to the low pH and hypertonicity, the expression and regulation of the acid sensing ion channel (ASIC)3 was examined.

MATERIALS AND METHODS

Expression of ASICs in cells of the intervertebral disc was analyzed. To study its regulation, we cloned the 2.8-kb rat ASIC3 promoter and performed luciferase reporter assays. The effect of pharmacological inhibition of ASICs on disc cell survival was studied by measuring MTT and caspase-3 activities.

RESULTS

ASIC3 was expressed in discal tissues and cultured disc cells in vitro. Because studies of neuronal cells have shown that ASIC3 expression and promoter activity is induced by nerve growth factor (NGF), we examined the effect of NGF on nucleus pulposus cells. Surprisingly, ASIC3 promoter activity did not increase after NGF treatment. The absence of induction was linked to nonexpression of tropomyosin-related kinase A (TrkA), a high-affinity NGF receptor, although a modest expression of p75NTR was seen. When treated with p75NTR antibody or transfected with dominant negative-p75NTR plasmid, there was significant suppression of ASIC3 basal promoter activity. To further explore the downstream mechanism of control of ASIC3 basal promoter activity, we blocked p75NTR and measured phospho extracellular matrix regulated kinase (pERK) levels. We found that DN-p75NTR suppressed NGF mediated transient ERK activation. Moreover, inhibition of ERK activity by dominant negative-mitogen activated protein kinase kinase (DN-MEK) resulted in a dose-dependent suppression of ASIC3 basal promoter activity, whereas overexpression of constitutively active MEK1 caused an increase in ASIC3 promoter activity. Finally, to gain insight in the functional importance of ASIC3, we suppressed ASIC activity in nucleus pulposus cells. Noteworthy, under both hyperosmotic and acidic conditions, ASIC3 served to promote cell survival and lower the activity of the pro-apoptosis protein, caspase-3.

CONCLUSIONS

Results of this study indicate that NGF serves to maintain the basal expression of ASIC3 through p75NTR and ERK signaling in discal cells. We suggest that ASIC3 is needed for adaptation of the nucleus pulposus and annulus fibrosus cells to the acidic and hyperosmotic microenvironment of the intervertebral disc.

Interleukin-6 Protein Expression Is More Important Than Interleukin-6 mRNA Levels in Assessing Surgical Invasiveness

BACKGROUND

Interleukin-6 (IL-6) protein has been recognized as a sensitive marker of surgical stress response. However, little is known about the clinical significance of IL-6 mRNA levels as a marker of surgical stress. This study aims to examine the role of IL-6 mRNA expression in comparing the tissue invasiveness of microendoscopic discectomy (MED) and open discectomy (OD).

METHODS

Twenty-three consecutive patients were randomly selected to undergo either MED or OD. The total RNA was extracted from the peripheral whole blood of patients at pre-op and at 1, 2, 4, 8, 12 h post-op. The real-time reverse transcription polymerase chain reaction (RT-PCR) using the SYBR Green I fluorescence dye and the 2(-DeltaDeltaCt) method was adopted to measure the IL-6 gene expression.

RESULTS

The quantitative changes of IL-6 mRNA expression in MED and OD patients at different times post-op differed significantly, P = 0.04. Experimental results indicate that the changes in IL-6 mRNA expression in OD and MED groups varied significantly at 1 h, 12 h post-op, 10.26-fold versus 4.42-fold and 52.15-fold versus 26.78-fold increase, respectively. Although IL-6 mRNA expression demonstrated an earlier difference than protein levels at 1 h post-op, IL-6 mRNA levels were found to be significantly affected after surgical procedures. Furthermore, compared with our enzyme-linked immunosorbent assay data, no significant correlation existed between IL-6 mRNA and protein levels at any post-op time interval.

CONCLUSIONS

We conclude that IL-6 mRNA expression using RT-PCR to extract the total RNA from a patient's peripheral whole blood is more sensitive than protein levels but can be significantly affected by surgical procedures. The enzyme-linked immunosorbent assay data on IL-6 protein expression are more consistent and significant than IL-6 mRNA levels in comparing tissue invasiveness between MED and OD.