Up-regulated osteogenic transcription factors during early response of human periodontal ligament stem cells to cyclic tensile strain

Introduction

As one group of periodontal ligament (PDL) cells, human periodontal ligament stem cells (hPDLSCs) have been isolated and identified as mesenchymal adult stem cells (MSCs) since 2004. It has been well accepted that PDL sensitively mediates the transmission of stress stimuli to the alveolar bone for periodontal tissue remolding. Besides, the direction of MSCs differentiation has been verified regulated by mechanical signals. Therefore, we hypothesized that tensile strain might act on hPDLSCs differentiation, and the early response to mechanical stress should be investigated.

Material and methods

The hPDLSCs were cultured in vitro and isolated via a magnetic activated CD146 cell sorting system. After investigation of surface markers and other experiments for identification, hPDLSCs were subjected to cyclic tensile strain at 3,000 µstrain for 3 h, 6 h, 12 h, and 24 h, without addition of osteogenic supplements. In the control groups, the cells were cultured in similar conditions without mechanical stimulation. Then osteogenic related genes and proteins were analyzed by RT-PCR and western blot.

Results

Cyclic tensile strain at 3,000 µstrain of 6 h, 12 h, and 24 h durations significantly increased mRNA and protein expressions of Satb2, Runx2, and Osx, which were not affected in unloaded hPDLSCs.

Conclusions

We indicate that hPDLSCs might be sensitive to cyclic tensile strain. The significant increase of Runx2, Osx and Satb2 expressions may suggest an early response toward osteogenic orientation of hPDLSCs.     

Influence of different intensities of vibration on proliferation and differentiation of human periodontal ligament stem cells

Introduction

To understand the effects of low-magnitude, high-frequency (LMHF) mechanical vibration at different intensities on human periodontal ligament stem cell (hPDLSC) proliferation and osteogenic differentiation.

Material and methods

The effect of vibration on hPDLSC proliferation, osteogenic differentiation, tenogenic differentiation and cytoskeleton was assessed at the cellular, genetic and protein level.

Results

The PDLSC proliferation was decreased after different magnitudes of mechanical vibration; however, there were no obvious senescent cells in the experimental and the static control group. Expression of osteogenesis markers was increased. The expression of alkaline phosphatase (ALP) and osteocalcin (OCN) mRNA was up-regulated at 0.1 g, 0.3 g, 0.6 g and 0.9 g magnitude, with the peak at 0.3 g. The type I collagen (Col-I) level was increased after vibration exposure at 0.1 g, 0.3 g, and 0.6 g, peaking at 0.3 g. The expression levels of both mRNA and protein of Runx2 and osterix (OSX) significantly increased at a magnitude of 0.1 g to 0.9 g, reached a peak at 0.3 g and then decreased slowly. The scleraxis, tenogenic markers, and mRNA expression decreased at 0.05 g, 0.1 g, and 0.3 g, and significantly increased at 0.6 g and 0.9 g. Compared with the static group, the F-actin stress fibers of hPDLSCs became thicker and clearer following vibration.

Conclusions

The LMHF mechanical vibration promotes PDLSC osteogenic differentiation and implies the existence of a magnitude-dependent effect of vibration on determining PDLSC commitment to the osteoblast lineage. Changes in the cytoskeleton of hPDLSCs after vibration may be one of the mechanisms of the biological effects.     

Age-related BMAL1 change affects mouse bone marrow stromal cell proliferation and osteo-differentiation potential

Introduction

Aging people''s bone regeneration potential is always impaired. Bone marrow stromal cells (MSCs) contain progenitors of osteoblasts. Donor age may affect MSCs’ proliferation and differentiation potential, but the genomic base is still unknown. Due to recent research''s indication that a core circadian component, brain and muscle ARNT-like 1 protein (BMAL1), has a role in premature aging, we investigated the normal aging mechanism in mice with their MSCs and Bmal1 gene/protein level.

Material and methods

1, 6 and 16 month old C57BL/6 mice were used and the bone marrow stromal cells were gained and cultured at early passage. Bmal1 gene and protein level were detected in these cells. Marrow stromal cells were also induced to differentiate to osteoblasts or adipocytes. Three groups of mice MSCs were compared on proliferation by flow cytometry, on cell senescence by SA-β-gal expression and after osteo-induction on osteogenic potential by the expression of osterix (Osx), alkaline phosphatase (ALP) and osteocalcin (OCN).

Results

Bmal1 gene and protein level as well as S-phase fraction of the cell cycle decreased in MSCs along with the aging process. At the same time, SA-β-gal+ levels increased, especially in the aged mice MSCs. When induced to be osteogenic, Osx gene expression and ALP activity declined in the mid-age and aged mice MSCs, while OCN protein secretion deteriorated in the aged mice MSCs.

Conclusions

These findings demonstrate that mouse MSCs changed with their proliferation and osteo-differentiation abilities at different aging stages, and that Bmal1 is related to the normal aging process in MSCs.     

Cyclic tension promotes osteogenic differentiation in human periodontal ligament stem cells

Orthodontic forces result in alveolar bone resorption and formation predominantly on the pressure and tension sides of the tooth roots, respectively. Human periodontal ligament stem cells (PDLSCs) have demonstrated the capacity to differentiate into osteoblasts, and they play important roles in maintaining homeostasis and regenerating periodontal tissues. However, little is known about how PDLSCs contribute to osteoblastogenesis during orthodontic tooth movement on the tension side. In this study, we applied a 12% cyclic tension force to PDLSCs cultured in osteoinductive medium. The osteogenic markers Runx2, ALP, and OCN were detected at the mRNA and protein levels at different time points using real-time PCR and western blot analyses. We discovered that the mRNA and protein levels of Runx2, ALP and OCN were significantly up-regulated after 6, 12 and 24 hours of mechanical loading on PDLSCs compared to levels in unstimulated PDLSCs (P < 0.05). This study demonstrates, for the first time, the effects of mechanical tensile strain on the osteogenic differentiation of PDLSCs, as examined with a Flexcell FX-4000T Tension Plus System. Our findings suggested that cyclic tension could promote the osteogenic differentiation of PDLSCs. Furthermore, the effects of orthodontic force on alveolar bone remodeling might be achieved by PDLSCs.     

Correlation between central venous pressure and peripheral venous pressure with passive leg raise in patients on mechanical ventilation

Background:

Central venous pressure (CVP) assesses the volume status of patients. However, this technique is not without complications. We, therefore, measured peripheral venous pressure (PVP) to see whether it can replace CVP.

Aims:

To evaluate the correlation and agreement between CVP and PVP after passive leg raise (PLR) in critically ill patients on mechanical ventilation.

Setting and Design:

Prospective observational study in Intensive Care Unit.

Methods:

Fifty critically ill patients on mechanical ventilation were included in the study. CVP and PVP measurements were taken using a water column manometer. Measurements were taken in the supine position and subsequently after a PLR of 45°.

Statistical Analysis:

Pearson''s correlation and Bland–Altman''s analysis.

Results:

This study showed a fair correlation between CVP and PVP after a PLR of 45° (correlation coefficient, r = 0.479; P = 0.0004) when the CVP was <10 cmH₂O. However, the correlation was good when the CVP was >10 cmH₂O. Bland–Altman analysis showed 95% limits of agreement to be −2.912–9.472.

Conclusion:

PVP can replace CVP for guiding fluid therapy in critically ill patients.     

Electroporation-mediated transfer of Runx2 and Osterix genes to enhance osteogenesis of adipose stem cells

In the present study, we tested the hypothesis that electroporation-mediated transfer of Runx2, Osterix, or both genes enhances the in vitro and in vivo osteogenesis from adipose stem cells (ASCs). ASCs were transfected with Runx2, Osterix, or both genes using electroporation, and further cultured in monolayer or in PLGA scaffold under osteogenic medium for 14 days, then analyzed for in vitro osteogenic differentiation. Transfected ASC-PLGA scaffold hybrids were also implanted on nude mice to test for in vivo ectopic bone formation. Runx2 and Osterix genes were strongly expressed in ASCs transfected with each gene on day 7, decreasing rapidly on day 14. Runx2 protein was strongly expressed in ASCs transfected with the Runx2 gene, while Osterix protein was strongly expressed in ASCs transfected with either or both Runx2 and Osterix genes. Overexpression of Runx2 and Osterix significantly increased the gene expression of osteogenic differentiation markers (alkaline phosphatase [ALP], osteocalcin [OCN], type I collagen [COL1A1], and bone sialoprotein [BSP]) in ASCs. Transfection of Runx2 and Osterix genes enhanced the protein expression of OCN, type I collagen, and BSP, as demonstrated by Western blot analysis, and ALP activity as well as enhancing mineralization in the monolayer culture and ASC-PLGA scaffold hybrids. Runx2- or Osterix-transfected ASC-PLGA scaffold hybrids promoted bone formation in nude mice after 6 weeks of in vivo implantation.     

Assessment of apoptosis,MMP-1, MMP-3, TIMP-2 expression and mechanical and biochemical properties of fresh rabbit's medial meniscus stored two weeks under tissue culture conditions

Introduction

The purpose of this study was to assess apoptosis, the expression of MMP-1, MMP-3 and TIMP-2, as well as the mechanical and biochemical properties of fresh rabbit medial meniscus after 2 weeks stored under tissue culture conditions.

Material and methods

The study material included 26 rabbit''s medial menisci. Fourteen menisci were stored for 2 weeks under tissue culture conditions. Thirteen menisci were subjected to immunohistochemistry tests. Apoptosis (TUNEL method) and the expression of MMP-1 (collagenase-1), MMP-3 (stromelysin-2) and TIMP-2 (tissue inhibitor of metalloproteinases-2) were estimated semiquantitatively. The remaining menisci were tested mechanically and biochemically. The mechanical properties were assessed by the degree of elasticity. Biochemical composition was based on the content analysis of water, total collagen and glycosaminoglycans.

Results

As in the control group, the conducted study did not reveal any apoptosis in the stored menisci. The study group showed a slight expression of MMP-1 (0.27 ±0.19), MMP-3 (0.30 ±0.20) and TIMP-2 (0.33 ±0.20) – no statistically significant difference from controls. The degree of elasticity was 28.51 ±1.53 in the study group, and this did not statistically differ from the control group. No significant biochemical differences were identified in any other monitored parameter.

Conclusions

The conducted in vitro study did not show any negative influence of a 2-week storage period under tissue culture conditions on the apoptosis and expression of MMP-1, MMP-3 and TIMP-2 in rabbit fresh menisci, nor any impact on their mechanical and biochemical properties.     

Laryngeal air column width ratio in predicting post extubation stridor

Aim:

Correlation of upper air column width ratio in postextubation stridor patients.

Materials and Methods:

A prospective observational study was conducted in a tertiary hospital between January and December 2013. Patients who were admitted in Intensive Care Unit and intubated for >24 h were included (72 patients). The upper airway air column width ratio (air column width before extubation/air column width after intubation) was calculated and compared in patient with or without postextubation stridor.

Results:

The incidence of stridor was 6.9% (5/72). The duration of mechanical ventilation was 5.60 ± 1.14 days and 3.91 ± 1.45 days in stridor and nonstridor group respectively. In all 5 patients who had stridor, the upper airway air column width ratio was 0.8 or less.

Conclusion:

Air column width ratio of 0.8 or less may be helpful in predicting postextubation stridor, which should be confirmed by large observational studies.     

Elevated procalcitonin is associated with increased mortality in patients with scrub typhus infection needing intensive care admission

Context:

Procalcitonin is a biomarker of bacterial sepsis. It is unclear if scrub typhus, a rickettsial illness, is associated with elevated procalcitonin levels.

Aim:

To assess if scrub typhus infection is associated with high procalcitonin levels and whether high levels portend a poorer prognosis.

Setting and Design:

Retrospective study of patients with severe scrub typhus infection, admitted to the medical intensive care unit of a tertiary care university affiliated teaching hospital.

Materials and Methods:

Eighty-four patients with severe scrub typhus infection that also had procalcitonin levels were assessed.

Statistical Analysis:

Relationship between procalcitonin and mortality explored using univariate and multivariate analyses.

Results:

The mean (±standard deviation) age was 40.0 ± 15.5 years. Patients were symptomatic for 8.3 ± 4.3 days prior to presentation. The median admission procalcitonin level was 4.0 (interquartile range 1.8 to 8.5) ng/ml; 59 (70.2%) patients had levels >2 ng/ml. Invasive mechanical ventilation was required in 65 patients; 20 patients died. On univariate analysis, admission procalcitonin was associated with increased odds of death [odds ratio (OR) 1.09, 95% confidence interval (CI) 1.03 to 1.18]. On multivariate logistic regression analysis including procalcitonin and APACHE-II score, the APACHE-II score was significantly associated with mortality (OR 1.16, 95% CI 1.06 to 1.30, P = 0.004) while a trend was observed with procalcitonin (OR 1.05, 95%CI 1.01 to 1.13, P = 0.09). The area under the receiver operating characteristic (ROC) curve, AUC, for mortality was 0.77 for procalcitonin and 0.78 for APACHE-II.

Conclusions:

Procalcitonin is elevated in severe scrub typhus infection and may be associated with higher mortality.     

Can integrative weaning index be a routine predictor for weaning success?

Objective:

To assess the effectiveness of integrative weaning index (IWI) as a predictor of weaning success.

Materials and Methods:

This is a prospective randomized controlled observer-blinded study and carried out on 120 patients of both sexes; patients who received mechanical ventilation for more than 24 h and met defined criteria for a weaning trial, underwent a 2-h spontaneous breathing trial with either IWI plus routine criteria of weaning (Group I n = 60) or routine criteria of weaning alone (control group) (Group C n = 60), in Group C the IWI was measured retrospective as it is not used in weaning decision. Those tolerated the trial would be immediately extubated. The primary outcome measure was the ability to maintain spontaneous, unassisted breathing for more than 48 h after extubation. Secondary outcome measures were the duration of mechanical ventilation, length of Intensive Care Unit (ICU) stay, and length of hospital stay.

Results:

The mean duration (hours) of mechanical ventilation and length of ICU stay (days) were significantly shorter in the Group I where the IWI was used (83.6 ± 34.3 vs. 97.49 ± 47.2 h, P = 0.002 and 5.5 ± 1.6 vs. 7.12 ± 2.3 days, P = 0.03, respectively). Weaning success rate was significantly higher in the Group I (53 vs. 34, P = 0.0001) while weaning failure rate was significantly lower in the Group I C (7 vs. 26, P = 0.0001).

Conclusion:

IWI is a strong predictor of both successful and failed weaning.     

Static tensioning promotes hamstring tendons force relaxation more reliably than cycling tensioning

Background

Graft elongation might be a major reason for increased anterior laxity after anterior cruciate ligament (ACL) reconstruction. This study analyzed the force relaxation values and their stabilization when single strands of the gracilis and semitendinosus tendons underwent cyclic and static tensioning at 2.5% strain level, and compared the efficiency of static and cyclic tensioning in promoting force relaxation.

Estimation of TGF-β1 genotypes in Egyptian smokers; association with FEV1 in COPD patients

Introduction

TGF-β1 is a cytokine with many different effects on cell proliferation, differentiation and inflammation and can protect against the development of COPD. This work aims to study the association between COPD and the TGF-β1 gene genotypes.

Material and methods

The study included 70 males: 25 smokers with COPD, 25 resistant smokers, and 20 normal non-smokers as the control. They were subjected to spirometry pre- and post-bronchodilator (FEV₁, FEV₁/FVC), estimation of serum level of TGF-β1 gene by PCR and RFLP.

Results

The percent of Pro-Leu was 28% in the COPD group, 84% in the resistant smokers group and 85% in the control group. There was a highly significant statistical difference in FEV₁% of predicted associated with the distribution of TGF-β1 gene genotypes: 56.9 ±8.4% with Pro-Leu genotype and 35.5 ±8.8% with Leu-Leu genotype in COPD patients, 93.2 ±6.2% with Pro-Leu genotype and 86.7 ±0.9% with Leu-Leu genotype in the resistant smokers group.

Conclusions

The Pro-allele genotype is associated with increased production of TGF-β1, which has a protective role against the development of COPD and is important in preserving the decline of FEV₁ in COPD patients.     

A comparison of clinical efficacy between high frequency oscillatory ventilation and conventional ventilation with lung volume recruitment in pediatric acute respiratory distress syndrome: A randomized controlled trial

Purpose:

To determine the efficacy of lung volume recruitment maneuver (LVRM) with high frequency oscillatory ventilation (HFOV) on oxygenation, hemodynamic alteration, and clinical outcomes when compared to conventional mechanical ventilation (CV) in children with severe acute respiratory distress syndrome (ARDS).

Materials:

We performed a randomized controlled trial and enrolled pediatric patients who were diagnosed to have severe ARDS upon pediatric intensive care unit (PICU) admission. LVRM protocol combined with HFOV or conventional mechanical ventilation was used. Baseline characteristic data, oxygenation, hemodynamic parameters, and clinical outcomes were recorded.

Results:

Eighteen children with severe ARDS were enrolled in our study. The primary cause of ARDS was pneumonia (91.7%). Their mean age was 47.7 ± 61.2 (m) and body weight was 25.3 ± 27.1 (kg). Their initial pediatric risk of mortality score 3 and pediatric logistic organ dysfunction were 12 ± 9.2 and 15.9 ± 12.8, respectively. The initial mean oxygen index was 24.5 ± 10.4, and mean PaO₂/FiO₂ was 80.6 ± 25. There was no difference in oxygen parameters at baseline the between two groups. There was a significant increase in PaO₂/FiO₂ (119.2 ± 41.1, 49.6 ± 30.6, P = 0.01*) response after 1 h of LVRM with HFOV compare to CV. Hemodynamic and serious complications were not significantly affected after LVRM. The overall PICU mortality of our severe ARDS at 28 days was 16.7%. Three patients in CV with LVRM group failed to wean oxygen requirement and were cross-over to HFOV group.

Conclusions:

HFOV combined with LVRM in severe pediatric ARDS had superior oxygenation and tended to have better clinical effect over CV. There is no significant effect on hemodynamic parameters. Moreover, no serious complication was noted.     

Gradual sucrose gastric loading test: A method for the prediction of nonsuccess gastric enteral feeding in critically ill surgical patients

Background and Aims:

Intolerance of gastric enteral feeding (GEN) commonly occurs in surgical Intensive Care Unit (SICU). A liquid containing sugar could prolong gastric emptying time. This study was to propose a method for prediction of nonsuccess GEN using gastric volume after loading (GVAL) following gradual sucrose gastric loading.

Materials and Methods:

Mechanical ventilator supported and hemodynamically stable patients in SICU were enrolled. About 180-240 min before the GEN starting, a sucrose solution (12.5%; 450 mosmole/kg, 800 mL) was administered via gastric feeding tube over 30 min with 45° head upright position. GVAL was measured at 30, 60, 90, and 120 min after loading. GEN success status using clinical criteria was assessed at 72 h after the starting GEN protocol. The receiving operating characteristic (ROC) and c statistic were used for discrimination at each time point of GVAL.

Results:

A total of 32 patients were enrolled and completed the protocol. 14 patients (43.7%) were nonsuccessful GEN. The nonsuccess group was found to have significantly more GVAL than the other group at all-time points during the test (P < 0.05). The most discriminating point of GVAL for the prediction of nonsuccess was 150 mL at 120 min after loading with a sensitivity of 92.3%, specificity of 88.9%, positive predictive value of 85.7%, negative predictive value of 94.1%, and ROC area 0.97 (95% confidence interval 0.91–1.00).

Conclusion:

A high GVAL following sucrose gastric loading test might be a method to predict nonsuccess GEN in critically ill surgical patients.     

Mental health status among younger generation around Chernobyl

Introduction

In order to improve our understanding of how to approach the younger generation around Chernobyl, we screened mental health status among young adults born after the accident living in the Gomel region, Belarus.

Material and methods

We enrolled 697 medical students who were born after the accident. Participants were asked to answer self-administered questionnaires including the General Health Questionnaire (GHQ-12).

Results

GHQ-12 scores were 1.80 ±2.28 (mean ± SD) among all 697 subjects. When logistic regression analysis was performed with confounding factors, “economic situation” and “association of diseases and/or poor health condition with radiation exposure” were significantly associated with poor mental status.

Conclusions

Our findings suggest that anxiety about radiation exposure among highly educated medical students in the Gomel region, although they were born after the accident, affects their poor mental health status.     

Pathogenic activity of circulating anti-desmoglein-3 autoantibodies isolated from pemphigus vulgaris patients

Introduction

There are scarce data on immunochemical properties of pemphigus antibodies detected in clinical remission in pemphigus vulgaris (PV) patients. The aim of the study was to compare biological activity of anti-Dsg3 autoantibodies purified from the sera of PV patients in active stage and in clinical remission.

Material and methods

The effect of purified antibodies on expression of procaspase-3, Bax, Bcl-2, uPAR, IL-1β, IL-6, and TNF-α mRNAs in the HaCaT keratinocytes was evaluated by Western blot and RT-PCR method.

Results

Incubation of HaCaT cells with anti-Dsg-3 autoantibodies caused their binding to cell membranes surfaces. Anti-Dsg3 autoantibodies isolated from the patients in active stage and clinical remission showed proapoptotic effect, caused enhanced expression of analyzed proinflammatory cytokines’ mRNAs and uPAR mRNA.

Conclusions

Our data revealed similar pathogenic activity of anti Dsg-3 autoantibodies isolated from active and clinical remission PV patients.     

Treatment with double dose of omeprazole increases β-endorphin plasma level in patients with coronary artery disease

Introduction

The proton pump inhibitor empirical trial, besides the analysis of symptoms, is the main method in the diagnosis of gastro-oesophageal reflux disease-related chest pain. β-Endorphin acts as an endogenous analgesia system. The aim of the study was verify whether β-endorphin plasma level is affected by omeprazole administration and influences the severity of anginal symptoms and outcome of the “omeprazole test” in patients with coronary artery disease (CAD) and chest pain of suspected non-cardiac origin.

Material and methods

Omeprazole was administered to 48 patients with CAD in a randomized, placebo-controlled, crossover study design. At the beginning of the study, and again after the 14-day omeprazole and placebo treatment, the β-endorphin plasma concentration was determined.

Results

The level of plasma β-endorphin after the administration of omeprazole was significantly greater than at the start of the study and following the placebo. Responders to omeprazole had an average lower β-endorphin plasma concentration than subjects who failed to respond to this therapy. Subjects with symptoms in class III (according to the Canadian Cardiovascular Society classification) after omeprazole administration had a greater β-endorphin plasma level than subjects in class II for anginal symptom severity.

Conclusions

Fourteen-day therapy with a double omeprazole dose significantly increases the β-endorphin plasma concentration in patients with CAD. Circulating β-endorphin does not seem to be involved in the mechanism for the “omeprazole test” outcome, although an individually different effect on pain threshold cannot be excluded.     

Role of acute physiology and chronic health evaluation II scoring system in determining the severity and prognosis of critically ill patients in pediatric intensive care unit

Objective:

This study was conducted to validate the use of Acute Physiology and Chronic Health Evaluation II (APACHE II) scoring system in pediatric population in predicting the risk of mortality and to compare the predicted death rate (using APACHE II) with the actual death rate of the patients.

Design:

Hospital-based prospective study.

Setting:

Tertiary care Pediatric Intensive Care Unit (PICU) in Western Rajasthan, India.

Methods:

A total of 100 critically ill children between 1 and 18 years of age admitted to PICU and fulfilling the inclusion criteria were enrolled. APACHE II score was calculated in each patient on the day of admission. The predicted mortality was calculated on the basis of this score.

Results:

The mean APACHE II score was 21.35 ± 5.76. Mean APACHE II score among the survivors was 16.60 ± 6.12, and mean APACHE II score among the nonsurvivors was 26.11 ± 5.41, and the difference was statistically significant (P = 0.00). The area under the receiver operating characteristic curve for APACHE II score was found to be 0.889 (P = 0.008) indicating good discrimination.

Conclusion:

APACHE II scoring system has a good discrimination and calibration when applied to a pediatric population.     

Relationship between exercise-induced heart rate increase and the formation of microbubbles and high-intensity transient signals in mechanical heart valve implanted patients

Introduction

The formation and collapse of vapor-filled bubbles near a mechanical heart valve is called cavitation. Microbubbles can be detected in vivo by doppler ultrasonography (USG) as HITS (high intensity transient signals) in cranial circulation. We investigated the relationship between exercise induced heart rate increase and HITS formation in cranial circulation.

Material and methods

Thirty-nine mechanical heart valve implanted (8 aortic valve replacement (AVR) + mitral valve replacement (MVR), 9 AVR, 22 MVR) patients aged 18-80 years old were included in our study. Microbubbles were counted in the left ventricular cavity via transthoracic echocardiography at rest per cardiac cycle. Afterwards transcranial Doppler USG was performed and HITS were counted in each patient''s middle cerebral artery at 5 min duration. Subsequently an exercise test according to the Bruce protocol was performed. After achieving maximal heart rate, microbubbles in the left ventricle and HITS were counted again.

Results

Microbubbles in the left ventricle and transcranial HITS increased after exercise significantly compared to resting values (15.79 ±10.91 microbubbles/beat vs. 26.51 ±18.00 microbubbles/beat, p < 0.001; 6.13 ±8.07 HITS/5 min vs. 13.15 ±15.87 HITS/5 min, p = 0.001). There was a significant correlation between microbubbles and HITS counts after peak exercise (r = 0.55, p < 0.001).

Conclusions

In our study, we found that the microbubbles were increasing as the heart rate increased and more HITS were propelled to the cerebral circulation. As previously shown, HITS can alter cognitive functions. Therefore heart rate control is essential in mechanical heart valve patients to protect neurocognitive functions.     

Evidence for apoptosis,MMP-1, MMP-3 and TIMP-2 expression and their effect on the mechanical and biochemical properties of fresh viable knee medial meniscal allografts and autografts in the rabbit

Introduction

The study sought evidence for apoptosis, the expression of MMP-1, MMP-3 and TIMP-2 and their effect on the mechanical and biochemical properties of rabbit fresh knee medial meniscal grafts in a 6-month follow-up.

Material and methods

Forty white male New Zealand rabbits were chosen for the study. The medial meniscus was excised from 28 animals and stored under tissue culture conditions for 2 weeks, following which 14 of them were implanted as autografts and 14 as allografts. When the animals were euthanized, 20 menisci were used for immunohistochemical examinations. Apoptosis (TUNEL method) and MMP-1, MMP-3 and TIMP-2 immunoexpression were estimated semiquantitatively. The other 20 menisci were subjected to biochemical analysis and their degree of elasticity was evaluated.

Results

An increased level of apoptosis (p <0.05) was observed both in allografts (1.57 ±0.98) and autografts (0.86 ±0.69); no statistical differences existed between them. An increased level of metalloproteinases and TIMP-2 expression was observed only in the allografts (p < 0.05). The highest decrease of degree of elasticity and the most significant changes in biochemical composition were observed in allografts (p < 0.05).

Conclusions

The studies confirmed the existence of excessive apoptosis in both kinds of fresh viable medial meniscal implants: auto- and allografts. Our results suggest that apoptosis and increased MMP-1 and MMP-3 expression have an adverse effect on the biological properties of implants. The results of experimental studies on humans indicate the need to devise a method of apoptosis inhibition in transplanted menisci to improve long-term results.