Optical tweezers for measuring red blood cell elasticity: application to the study of drug response in sickle cell disease

The deformability of erythrocytes is a critical determinant of blood flow in microcirculation. By capturing red blood cells (RBC) with optical tweezers and dragging them through a viscous fluid we were able to measure their overall elasticity. We measured, and compared, the RBC deformability of 15 homozygous patients (HbSS) including five patients taking hydroxyurea (HU) for at least 6 months (HbSS/HU), 10 subjects with sickle cell trait (HbAS) and 35 normal controls. Our results showed that the RBC deformability was significantly lower in haemoglobin S (HbS) subjects (HbSS and HbAS), except for HbSS/HU cells, whose deformability was similar to the normal controls. Our data showed that the laser optical tweezers technique is able to detect differences in HbS RBC from subjects taking HU, and to differentiate RBC from normal controls and HbAS, indicating that this is a very sensitive method and can be applied for detection of drug-response in sickle cell disease.

Short term inhalation toxicity of a liquid aerosol of CdS/Cd(OH)₂ core shell quantum dots in male Wistar rats

Colloidal quantum dots (QD) show great promise as fluorescent markers. The QD used in this study were obtained in aqueous medium rather than the widely used colloidal QD. Both methodologies used for the production of QD are associated with the presence of heavy metals such as cadmium (Cd). Here we investigate the short-term inhalation toxicity of water-soluble core-shell CdS/Cd(OH)₂ QD. Male Wistar rats were head-nose exposed for 6 h/day on 5 days at the technically maximum concentration (0.52 mg Cd/m³). Histological examination was performed directly after the last exposure. Additional rats were used for Cd organ burden determinations. Clinical parameters in blood, bronchoalveolar lavage fluid and lung tissue were determined 3 days after the last exposure. To analyze the reversibility or progression of effects, the examinations were performed again after a recovery period of 3 weeks. The results of the study indicate that CdS/Cd(OH)₂ QD caused local neutrophil inflammation in the lungs that partially regressed after the 3-week recovery period. There was no evidence that QD were translocated to the central nervous system nor that a systemic acute phase response occurred.

Photodynamic effect of zinc porphyrin on the promastigote and amastigote forms ofLeishmania braziliensis

Zn(ii)meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin was applied in the photodynamic inactivation ofLeishmania braziliensis, leading to considerable cell damage.

Human papillomavirus as a risk factor in oral carcinogenesis: a study using in situ hybridization with signal amplification

INTRODUCTION

It is still controversial whether human papillomavirus (HPV) can be considered a risk factor in oral carcinogenesis. The aim of this study was to detect HPV DNA in 50 cases diagnosed as oral leukoplakias, with different degrees of epithelial dysplasia, and as oral squamous cell carcinomas, using in situ hybridization with signal amplification (CSA-ISH).

METHODS

HPV DNA was assessed in paraffin sections using CSA-ISH with a wide-spectrum biotinylated DNA probe. In HPV-positive cases, genotyping with specific probes to HPV types 6/11, 16/18 and 31/33 was performed.

RESULTS

The overall prevalence of HPV infection was 24%, markedly higher than that found in the control group. Results showed a discrete proportional relationship in the indices found in leukoplakia with no dysplasia, leukoplakia with dysplasia, and squamous cell carcinoma, but this was not statistically significant. When separating the group of leukoplakia by degrees of dysplasia, this relation of proportion was not observed. In genotyping, HPV types 16/18 were the most prevalent, and types 6/11 were only found in groups of mild or no dysplasia.

CONCLUSION

The results suggest that HPV is not likely to play a role in the progression of malignant transformation in oral lesions. Nevertheless, the increased prevalence of HPV infection compared to normal oral mucosa and the fact that high-risk HPV types were the most frequently identified do not allow the exclusion of HPV as a risk factor in oral carcinogenesis.

Acceptability of computer assessments among ethnically diverse, low-income smokers

PURPOSE

To examine the acceptability of computer-based assessments among an ethnically diverse, low-income population of primary care patients. Although computers have been used to provide assessments and interventions in health care settings, members of ethnic minority and low-income households have less access to computers than other groups, and therefore the acceptability of computers as a health care assessment and delivery tool needs to be examined.

DESIGN

We examined the acceptability of computers for providing assessments of smoking history, nicotine dependence, and other related variables among an ethnically diverse, low-income primary care population. No intervention was used in this study.

SETTING

Three inner-city primary care clinics located in hospitals were used as sites for this study. These hospitals were located in areas of the city where low-income and ethnic minority households are overrepresented relative to the total population.

SUBJECTS

Adult male and female smokers (n = 522) were recruited while awaiting appointments in each primary care clinic.

MEASURES

A questionnaire assessing smoking rate, patterns, history, motivation to quit smoking, and other smoking-related variables was administered using either a paper-and-pencil format or a laptop computer.

RESULTS

Frequency counts, analysis of variance, and chi 2 tests were used where appropriate. Most subjects (78.5%) used the computer to complete the baseline survey. Almost all subjects (92%) rated the computer "very easy" or "easy" to use. Subjects who were Spanish-speaking, were born outside the United States, or were Hispanic tended to rate the program as slightly less easy to use than other subjects.

CONCLUSIONS

Computer-based assessments appear highly acceptable to individuals in low-income populations.

Core-shell CdS/Cd(OH)2 quantum dots: synthesis and bioconjugation to target red cells antigens

We report a new and efficient methodology of labelling red blood cells, in order to investigate the expression of anti-A antigen, employing luminescent semiconductor nanocrystals. Highly luminescent and stable core-shell cadmium sulphide/cadmium hydroxide [CdS/CdS(OH)2] colloidal particles were obtained in the nanometre size range. The surface of these particles was characterized by using a monoclonal anti-A antibody via a one-step glutaraldehyde cross-linking procedure, followed by conjugation of the particles to red cells of blood groups A+, and O+. Laser scanning confocal microscopy images indicated that after conjugation for 30 min, A+ and erythrocytes presented different patterns of dual bright emission whereas the O+ group cells showed no emission. We suggest that this labelling procedure may be applied as a quantitative tool to investigate the distribution and expression of alloantigen in red blood cells.

Elastic properties of stored red blood cells from sickle trait donor units

BACKGROUND AND OBJECTIVES

Red blood cells (RBCs) from patients with sickle cell disease present reduced deformability. The aim of this study was to analyse the elasticity of stored RBCs from patients with the sickle cell trait (AS).

MATERIALS AND METHODS

The cell elasticity was studied, using laser optical tweezers, on storage days 1, 14, 21, 28 and 35.

RESULTS

The elasticity of RBC from AS units stored for 1, 14 and 21 days was significantly greater compared with that of control RBC cells stored for the same time-period. More than 30% of the cells from AS units stored for 28 or 35 days were very rigid and escaped from the optical trap.

CONCLUSIONS

RBCs became rigid during storage, suggesting that haemoglobin S might compromise the cell elasticity.

Activity of glucocerebrosidase in extracts of different cell types from type 1 Gaucher disease patients

Glucocerebrosidase activity in extracts of leukocytes, Epstein-Barr virus transformed lymphocytes and fibroblasts from Portuguese Type 1 Gaucher disease patients was studied. The residual glucocerebrosidase activity in all extracts from patients was less than 25% if measured in the presence of bile salt taurocholate. However, if measured in the absence of bile salt the residual enzyme activity in extracts from patients was cell type specific: it was severely reduced in the case of fibroblasts, mildly reduced in the case of lymphoblasts and not significantly reduced in the case of leukocytes. The glucocerebrosidase activity in extracts from all control cell types was stimulated by taurocholate. In the patients the enzyme activity in fibroblasts extracts was also stimulated but that in lymphoblasts and leukocytes was inhibited by the bile salt. The differences in glucocerebrosidase activity (in the absence of taurocholate) in extracts from different cell types from Gaucher disease patients are attributable to differences in the proportion of glucocerebrosidase present as a monomer with low activity (form I) and as a highly active aggregate (form II) that may also contain sphingolipid activator protein 2 (SAP-2). In extracts from leukocytes and lymphocytes from Type 1 Gaucher disease patients, but not in those from fibroblasts, a relatively high proportion of enzyme is present in aggregated form with near normal specific activity.

Clinical, enzymatic, and molecular characterisation of a Portuguese family with a chronic form of GM2-gangliosidosis B1 variant

Mutations in the hexosaminidase A gene (HEXA) causing the B1 variant of GM2-gangliosidosis result in the presence of a mutant enzyme protein with a catalytically defective alpha subunit. A rare and panethnically distributed mutation, transition G533A (Arg178His), is known to be a common allele among Portuguese patients with the subacute phenotype. We now report the presence of an Arg178His allele in three Portuguese sibs with a chronic form of the disease, who carry the transition G755A (Arg252His) on the second allele. This novel mutation is the first B1 allele to be associated with an adult phenotype.

Vitamin E nanoemulsion activity on stored red blood cells

BACKGROUND

Stored red blood cells (RBCs) undergo numerous changes that have been termed RBC storage lesion, which can be related to oxidative damage. Vitamin E is an important antioxidant, acting on cell lipids. Thus, this study aimed to investigate vitamin E activity on stored RBCs.

METHODS

We prepared a vitamin E nanoemulsion that was added to RBC units and stored at 4 °C. Controls, without vitamin E, were kept under the same conditions. Reactive oxygen species (ROS) production was monitored for up to 35 days of storage. RBC elasticity was also evaluated using an optical tweezer system.

RESULTS

Vitamin E-treated samples presented a significant decrease in ROS production. Additionally, the elastic constant for vitamin E-treated RBCs did not differ from the control.

CONCLUSION

Vitamin E decreased the amount of ROS in stored RBCs. Because vitamin E acts on lipid oxidation, results suggest that protein oxidation should also be considered a key factor for erythrocyte elastic properties. Thus, further studies combining vitamin E with protein antioxidants deserve attention, aiming to better preserve overall stored RBC properties.

High specific immune response to a bivalent anti-HPV vaccine in HIV-1-infected men in São Paulo, Brazil

INTRODUCTION

Infection with Human papillomavirus (HPV) has been reported as one of the most prevalent agent sexually transmitted diseases, but its true prevalence in men is not precisely known, mainly due to the near absence of symptoms. Moreover, few studies evaluating the post-vaccination immune response have been performed to date in men, hence the hypotheses tested in this study can be important to enable a better understanding of both the immunopathogenesis and the response to vaccination in HIV-infected patients, and to help in the elaboration of strategies of vaccination against HPV in the HIV-infected population.

OBJECTIVES

To analyze the specific response to antigens of HPV vaccine in HIV-infected men.

METHODS

A total of 25 HIV-infected male patients who met the inclusion criteria during the data collection period were vaccinated; however, six (30%) had anti-HPV at baseline, and were not considered further in the analysis. Therefore, 19 HIV-infected individuals were included in the study, along with five healthy, HPV-seronegative controls.

RESULTS

Patients infected with HIV-1 were subdivided into two groups, A and B, according to their T CD4 cells count at the time of vaccination, namely: Group A: CD4>500; Group B: CD4<500. The proportion of seroconversion after immunization with three doses of a bivalent anti-HPV vaccine was 92%.

CONCLUSION

HIV-infected patients as well as HIV negative controls responded to anti-HPV vaccination, regardless of their T CD4 cells count and HIV plasma viral load. These results demonstrate that anti-HPV immunization in HIV-infected males is effective and should be encouraged, thus helping to decrease the risk of infection, mortality and morbidity of diseases associated with HPV in men.

Biomechanical and biochemical investigation of erythrocytes in late stage human leptospirosis

Leptospirosis is a zoonotic disease caused by bacteria of the genus Leptospira, which can cause lipid changes in the erythrocyte membrane. Optical tweezers were used to characterize rheological changes in erythrocytes from patients with leptospirosis in the late stage. Biochemical methods were also used for quantification of plasma lipid, erythrocyte membrane lipid, and evaluation of liver function. Our data showed that the mean elastic constant of erythrocytes from patients with leptospirosis was around 67% higher than the control (healthy individuals), indicating that patient’s erythrocytes were less elastic. In individuals with leptospirosis, several alterations in relation to control were observed in the plasma lipids, however, in the erythrocyte membrane, only phosphatidylcholine showed a significant difference compared to control, increasing around 41%. With respect to the evaluation of liver function of individuals with leptospirosis, there was a significant increase in levels of alanine transaminase (154%) and aspartate transaminase (150%), whereas albumin was 43.8% lower than control (P<0.01). The lecithin-cholesterol acyltransferase fractional activity was 3.6 times lower in individuals with leptospirosis than in the healthy individuals (P<0.01). The decrease of the erythrocyte elasticity may be related to the changes of erythrocyte membrane phospholipids composition caused by disturbances that occur during human leptospirosis, with phosphatidylcholine being a strong candidate in the erythrocyte rheological changes.

Raman, hyper-Raman, hyper-Rayleigh, two-photon luminescence and morphology-dependent resonance modes in a single optical tweezers system

We present a setup of optical tweezers combined with linear and nonlinear microspectroscopies that enhances the capabilities of capture and analysis of both techniques. We can use either a continuous-wave (cw) Ti:sapphire laser for Raman measurements or a pulsed femtosecond Ti:sapphire laser that permitted the observation of nonlinear results such as hyper-Raman, hyper-Rayleigh, and two-photon luminescence. Only the high peak intensity of the femtosecond laser allows the observation of all these nonlinear spectroscopies. The sensitivity of our system also permitted the observation of morphology-dependent resonance (MDR) modes of a single stained trapped microsphere of 6 microm. The possibility of performing spectroscopy in a living microorganism optically trapped in any desired neighborhood would mean that one can dynamically observe the chemical reactions and/or mechanical properties changing in real time.

Risk scores in predicting adverse events after an acute coronary syndrome

Funding Acknowledgements

Type of funding sources: None.

Introduction

ST-segment elevation myocardial infarction (STEMI) is a serious event that usually occur in patients with cardiovascular risk factors and is associated with great morbidity and mortality.

PARIS ischemic risk score and TIMI score were validated to evaluate ischemic risk in STEMI patients who underwent percutaneous coronary intervention (PCI) and to estimate mortality, respectively.

Despite these specific purposes, the usefulness of these scores in predicting adverse cardiovascular events (ACE) is unknown.

Objectives

To assess the prognostic value of PARIS and TIMI scores for cardiovascular events, coronary ischemic events and mortality in patients after STEMI.

Methods

Retrospective single center cohort study enrolled 103 patients with STEMI diagnosis between 2018 and 2019, during a mean follow-up period 30.30 ± 6.46 months and patients were included regardless of the reperfusion strategy.

Primary endpoint (PE) was a composite of acute coronary events (ACE), admissions to the emergency department by heart failure (HF) decompensation or chronic coronary syndrome and HF hospitalization. Secondary endpoint (SE) was ACE. Cardiovascular and non-cardiovascular death was determined.

PARIS ischemic risk score was calculated and patients were stratified into low (0-2), intermediate (3-4) or high (≥ 5) ischemic risk categories. TIMI score was also assessed.

Results

Out of 103 patients with STEMI diagnosis, the median age was 58.15 ± 12.6 years and 85,4% were male. Fifty-seven patients (55.3%) had hypertension, 45 (43.7%) dyslipidemia, 18 (17.5%) diabetes, 17 (15.5%) were obese and seventy-eight patients (75.7%) had history of smoking. Twenty (19.4%) patients had a previous acute coronary syndrome and 15 underwent PCI.

Twenty-five (24.3%) patients were included in low PARIS ischemic risk category, 53 (51.5%) in intermediate risk and 20 (19.4%) in high risk category.

PE occurred in 16 patient (15.5%) and SE in 7 patients (6.8%).

Eight patients died during the follow-up period (7.8%), 4 of cardiovascular causes (50%), 3 of non-cardiovascular causes (37.5%) and 1 of unknown cause.

PARIS ischemic risk score showed prognostic value for PE, with an area under the curve (AUC) of 0.65, 95% confidence interval (CI) 0.506-0.806 and p-value 0.039.

PARIS score also had predictive value for SE (AUC 0.816, 95% CI 0.604-1.000; p 0.004) as well as TIMI score (AUC 0.738, 95% CI 0.560 – 0.917; p 0.032).

Both scores showed a good prognostic value in evaluating all-cause mortality, with a slightly better predictive value for TIMI score (AUC 0.91, 95% CI 0.802 – 1.00) when compared to PARIS score (AUC 0.84, 95% CI 0.685 – 0.987).

Conclusion

This study revealed that PARIS and TIMI scores have a good discriminatory power to predict prognosis in STEMI patients. According to our study results, these scores could be an interesting tool to determine the likelihood of fatal and non-fatal outcomes, including ACS.

STEMI treatment in remote areas – challenges of the only interventional angioplasty center located in an archipelago

Background

In remote islands lack of specialized medical facilities, long distance transfer and emergency medical system organization remains a challenge and fibrinolysis is necessary to achieve revascularization in optimal timing in ST-elevation myocardial infarction (STEMI) patients. Our angioplasty center is the only one located in an archipelago composed of nine islands, six of which do not have hospital facilities and only have small family health care units.

Purpose

To evaluate the reality and outcomes of our interventional angioplasty center and compare cardiovascular outcomes between STEMI patients from the main island and remote islands.

Methods

We retrospectively evaluated 103 patients with STEMI admitted to our center between 2018 and 2019. Patients from the main island where the center is located underwent primary percutaneous coronary intervention (PCI) (group 1, n=55) and patients from remote islands underwent fibrinolytic therapy followed by transference to our center with facilitated or rescue PCI (group 2, n=48). A subanalysis of the far remote islands without hospital facilities was also performed. Primary outcome was defined as cardiovascular death or re-infarction at two years and secondary outcome as intrahospital haemorrhagic complications.

Results

Mean age was 58,15±12,6 years, 85,4% were males and follow up period was 30,30±6,46 months. Seventy-eight patients (75,7%) had history of smoking, 45 (43,7%) dyslipidemia, 20 (19,4%) previous acute coronary syndrome, 18 (17,5%) diabetes and 17 (15,5%) were obese. Troponin I peak was 117,42±129,06 ug/L and 14 (13,6%) were in Killip Class III/IV. Infarct-related artery was the left anterior descending artery in 45 (45,5%) and multivessel disease was present in 38 (38,0%). In group 1 reperfusion after PCI was obtained in 91,5%. In group 2, 73,5% met criteria for reperfusion after fibrinolysis and 23,6% after rescue PCI. Mean time from fibrinolysis to PCI was 558±349 minutes. Rates of successful revascularization did not differ between groups, as well as complete patency of the culprit-vessel defined as thrombolysis in myocardial infarction (TIMI) flow 3 (91,5% vs. 97,2% and 90,0% vs. 93,0% respectively for group 1 and 2). Cardiovascular death at two years occurred in 4 (3,9%) patients and re-infarction in 11 (10,7%) and were similar between groups (3 (5,5%) vs. 1 (2,1%) and 8 (14,5%) vs. 3 (6,3%) respectively) as well as haemorrhagic complications (1 (1,8%) vs. 5 (10,4%) respectively). Nineteen (18,4%) patients were from far remote islands without hospital facilities and when comparing these patients with the others there was also no difference in primary outcome.

Conclusion

Even in remote islands, an organized STEMI network with attempted fibrinolytic treatment and coordinated transference of patients for facilitated or rescue PCI can provide successful revascularization with cardiovascular outcomes similar to those submitted to primary PCI.

Funding Acknowledgement

Type of funding sources: None.