Photophysical characterization of tetrahydroxyphenyl porphyrin Zn(II) and V(IV) complexes: experimental and DFT study

Photodynamic therapy (PDT) is a promising technique for the treatment of various diseases. In this sense, the singlet oxygen quantum yield (Φ∆) is a physical-chemical property that allows to stablish the applicability of a potential photosensitizers (PS) as a drug for PDT. In the herein report, the Φ∆ of three photosensitizers was determined: metal-free tetrahydroxyphenyl porphyrin (THPP), THPP-Zn and the THPP-V metal complexes. Their biological application was also evaluated. Therefore, the in vitro study was carried out to assess their biological activity against Escherichia coli. The metal-porphyrin complexes exhibited highest activities against the bacterial strain Escherichia coli. at the highest concentration (175 μg/mL) and show better activity than the free base ligand (salts and blank solution). Results indicated a relation between Φ∆ and the inhibitory activity against Escherichia coli, thus, whereas higher is the Φ∆, higher is the inhibitory activity. The values of the Φ∆ and the inhibitory activity follows the tendency THPP-Zn > THPP > THPP-V. Furthermore, quantum chemical calculations allowed to gain deep insight into the electronic and optical properties of THPP-Zn macrocycle, which let to verify the most probable energy transfer pathway involved in the singlet oxygen generation.

Safety and efficacy of direct oral anticoagulants in patients with atrial fibrillation on concomitant treatment with dronedarone

Funding Acknowledgements

Type of funding sources: None.

Introduction

The use of direct oral anticoagulants (DOACs) in patients with atrial fibrillation (AF) is associated with bleedings. Interactions with dronedarone may increase this risk, but data on concomitant treatment of DOACs with dronedarone are limited.

Purpose

The primary endpoint was to compare the survival free from the composite endpoint of clinically relevant bleeding, thromboembolic event and all-cause death, between AF patients on treatment with dronedarone and different DOACs. The secondary endpoints were to compare the survival free from i) clinically relevant bleeding and ii) clinically relevant major bleeding.

Methods

A retrospective study was conducted at our Local Health Unit, from January 1st 2016 to December 31st 2020. The population included AF patients with concomitant prescriptions of DOACs and dronedarone. Patients were divided into 4 groups (rivaroxaban, apixaban, edoxaban, dabigatran). Clinically relevant major bleedings were defined as fatal bleeding or bleeding leading to transfusion of ≥2 units of blood. Clinically relevant non-major bleedings were defined as any sign of hemorrhage that does not fit the criteria for major bleeding but does lead to hospitalization or emergency room admission. Thromboembolic events were defined as ischemic stroke, transient ischemic attack (TIA), and systemic embolism.

Results

165 patients were included: 46/165 (28%) on rivaroxaban, 66/165 (40%) on apixaban, 45/165 (27%) on edoxaban, and 8/165 (5%) on dabigatran (Fig.1). Over a median follow-up of 339 days, 14/165 (8%) met the primary composite endpoint: 8/165 (5%) had clinically relevant bleedings, of which 1/165 (0.6%) was a clinically relevant major bleeding (i.e., fatal spontaneous intracerebral hemorrhage), 2/165 (1%) had TIAs, and 5/165 (3%) died. We found no difference in survival free from the primary composite endpoint and from clinically relevant bleeding between groups (p=0.19 and p=0.69, respectively) (Fig. 2A-B). However, survival free from clinically relevant major bleeding was significantly lower in dabigatran users (p=0.003) (Fig. 2C). At a secondary analysis, DOACs contraindicated by 2015 EHRA guide (dabigatran, edoxaban 60 mg), and not by 2018/2021 EHRA guides (rivaroxaban, dabigatran, edoxaban 60 mg), were associated with lower survival from either clinically relevant bleeding or clinically relevant major bleeding (p=0.03 and p<0.001, respectively).

Conclusions

In our study on patients on concomitant treatment with DOACs and dronedarone, there was no difference in survival free from the primary composite endpoint and from clinically relevant bleeding between groups of coadministration. However, survival free from clinically relevant major bleeding was significantly lower in dabigatran users. DOACs contraindicated by 2015 EHRA guide (and not by the latest 2018/2021 EHRA guides) are associated with lower survival from either clinically relevant bleeding or clinically relevant major bleeding.

C51 SAFETY AND EFFICACY OF DIRECT ORAL ANTICOAGULANTS IN PATIENTS WITH ATRIAL FIBRILLATION ON CONCOMITANT TREATMENT WITH DRONEDARONE

Background

The use of direct oral anticoagulants (DOACs) in patients with atrial fibrillation (AF) is associated with bleedings. Interactions with dronedarone may increase this risk, but data on concomitant treatment of DOACs with dronedarone are limited.

Aim

The primary endpoint was to compare the survival free from the composite endpoint of clinically relevant bleeding, thromboembolic event and death, between AF patients on treatment with dronedarone and different DOACs. The secondary endpoints were to compare the survival free from i) clinically relevant bleeding and ii) clinically relevant major bleeding.

Methods

A retrospective study was conducted at the Local Health Unit “Ulss3 Serenissima” of Venice, Italy, from January 1st 2016 to December 31st 2020. The eligible population included AF patients with concomitant prescriptions of DOACs and dronedarone. Patients were divided in 4 groups (rivaroxaban, apixaban, edoxaban, dabigatran).

Results

165 patients were included: 46/165 (28%) on rivaroxaban, 66/165 (40%) on apixaban, 45/165 (27%) on edoxaban, and 8/165 (5%) on dabigatran (Fig.1). Over a median follow–up of 339 days, 14/165 (8%) met the primary composite endpoint: 8/165 (5%) had clinically relevant bleedings, of which 1/165 (0.6%) was a clinically relevant major bleeding, 2/165 (1%) had TIAs, and 5/165 (3%) died. We found no difference in survival free from the primary composite endpoint and from clinically relevant bleeding between groups (log–rank test p = 0.19 and p = 0.69, respectively) (Fig. 2A–B). However, survival free from clinically relevant major bleeding was significantly lower in dabigatran users (p = 0.003) (Fig. 2C). At a secondary analysis, DOACs contraindicated by 2015 EHRA guide (dabigatran, edoxaban 60 mg), and not by 2018/2021 EHRA guides (rivaroxaban, dabigatran, edoxaban 60 mg), were associated with lower survival from either clinically relevant bleeding or clinically relevant major bleeding (log–rank test p = 0.03 and p < 0.001, respectively) (Fig. 3).

Conclusions

In our study, there was no difference in survival free from the primary composite endpoint and from clinically relevant bleeding between groups of coadministration. However, survival free from clinically relevant major bleeding was significantly lower in dabigatran users. DOACs contraindicated by 2015 EHRA guide (and not by the latest 2018/2021 EHRA guides) are associated with lower survival from either clinically relevant bleeding or clinically relevant major bleeding.

Comparative clinical prognosis of massive and non-massive pulmonary embolism: A registry-based cohort study

AIMS

Little is known about the prognosis of patients with massive pulmonary embolism (PE) and its risk of recurrent venous thromboembolism (VTE) compared with non-massive PE, which may inform clinical decisions. Our aim was to compare the risk of recurrent VTE, bleeding, and mortality after massive and non-massive PE during anticoagulation and after its discontinuation.

METHODS AND RESULTS

We included all participants in the RIETE registry who suffered a symptomatic, objectively confirmed segmental or more central PE. Massive PE was defined by a systolic hypotension at clinical presentation (<90 mm Hg). We compared the risks of recurrent VTE, major bleeding, and mortality using time-to-event multivariable competing risk modeling. There were 3.5% of massive PE among 38 996 patients with PE. During the anticoagulation period, massive PE was associated with a greater risk of major bleeding (subhazard ratio [sHR] 1.72, 95% confidence interval [CI] 1.28-2.32), but not of recurrent VTE (sHR 1.15, 95% CI 0.75-1.74) than non-massive PE. An increased risk of mortality was only observed in the first month after PE. After discontinuation of anticoagulation, among 11 579 patients, massive PE and non-massive PE had similar risks of mortality, bleeding, and recurrent VTE (sHR 0.85, 95% CI 0.51-1.40), but with different case fatality of recurrent PE (11.1% versus 2.4%, P = .03) and possibly different risk of recurrent fatal PE (sHR 3.65, 95% CI 0.82-16.24).

CONCLUSION

In this large prospective registry, the baseline hemodynamic status of the incident PE did not influence the risk of recurrent VTE, during and after the anticoagulation periods, but was possibly associated with recurrent PE of greater severity.

Infectivity and pathobiology of H7N1 and H5N8 high pathogenicity avian influenza viruses for pigeons (Columba livia var. domestica)

Avian influenza (AI) is one of the most important viral diseases in poultry, wildlife and humans. Available data indicate that pigeons play a minimum role in the epidemiology of AI. However, a degree of variation exists in the susceptibility of pigeons to highly pathogenic AI viruses (HPAIVs), especially since the emergence of the goose/Guangdong H5 lineage. Here, the pathogenesis of H5N8 HPAIV in comparison with a H7N1 HPAIV and the role of pigeons in the epidemiology of these viruses were evaluated. Local and urban pigeons (Columba livia var. domestica) were intranasally inoculated with 10⁵ ELD₅₀ of A/goose/Spain/IA17CR02699/2017 (H5N8) or A/Chicken/Italy/5093/1999 (H7N1) and monitored during 14 days. Several pigeons inoculated with H5N8 or H7N1 seroconverted. However, clinical signs, mortality, microscopic lesions and viral antigen were only detected in a local pigeon inoculated with H5N8 HPAIV. This pigeon presented prostration and neurological signs that correlated with the presence of large areas of necrosis and widespread AIV antigen in the central nervous system, indicating that the fatal outcome was associated with neurological dysfunction. Viral RNA in swabs was detected in some pigeons inoculated with H7N1 and H5N8, but it was inconsistent, short-term and at low titres. The present study demonstrates that the majority of pigeons were resistant to H5N8 and H7N1 HPAIVs, despite several pigeons developing asymptomatic infections. The limited viral shedding indicates a minimum role of pigeons as amplifiers of HPAIVs, regardless of the viral lineage, and suggests that this species may represent a low risk for environmental contamination. RESEARCH HIGHLIGHTS H7N1 and H5N8 HPAIVs can produce subclinical infections in pigeons. The mortality caused by H5N8 HPAIV in one pigeon was associated with neurological dysfunction. Pigeons represent a low risk for environmental contamination by HPAIVs.

Experimental infection of domestic geese (Anser anser var. domesticus) with H5N8 Gs/GD and H7N1 highly pathogenic avian influenza viruses

Prior to the emergence of the Asian-origin H5 Goose/Guangdong/1/96 (Gs/GD) lineage, highly pathogenic avian influenza viruses (HPAIV) had rarely caused high mortalities in domestic geese. In 2016/2017 European epidemics, H5N8 Gs/GD clade 2.3.4.4 Group B produced an unprecedented number of outbreaks in waterfowl holdings. In this study, the pathogenesis of H5N8 HPAIV in comparison with H7N1 HPAIV, and the role of domestic geese in the epidemiology of these viruses, were evaluated. Local and commercial geese (Anser anser var. domesticus) were intranasally inoculated with 10⁵ ELD₅₀ of A/goose/Spain/IA17CR02699/2017 (H5N8) or A/Chicken/Italy/5093/1999 (H7N1) and monitored daily during 15 days. H5N8 was highly virulent to domestic geese, reaching 100% mortality by 10 days post-infection. Systemic microscopic necrotizing lesions associated with widespread AIV-antigen were detected by IHC techniques, the central nervous system being the most severely affected. High viral loads, measured by qRT-PCR, were present in all samples collected: oral and cloacal swabs, plasma tissues, and moderate levels in pool water. Domestic geese were also susceptible to H7N1 infection, as demonstrated by seroconversion and detection of viral RNA in tissues and plasma in some geese, but all lacked clinical signs. Viral shedding was confirmed in only some geese and was restricted to the oral route, but levels were high and still detected at the end of the study. Overall, H7N1 presents a lower lethality and shedding than H5N8 in geese; however, the viral shedding indicates that these species could play a role in the epidemiology of Gs/GD and other lineages of HPAIVs. RESEARCH HIGHLIGHTS H5N8 Gs/GD clade 2.3.4.4 Group B is highly virulent to domestic geese. The severity of H5N8 is associated with multisystemic replication. H7N1 can infect domestic geese but is avirulent to this species. Domestic geese could play a role in the epidemiology of Gs/GD HPAIVs.

D-dimer levels and risk of recurrence following provoked venous thromboembolism: findings from the RIETE registry

BACKGROUND

Patients with venous thromboembolism (VTE) secondary to transient risk factors may develop VTE recurrences after discontinuing anticoagulation. Identifying at-risk patients could help to guide the duration of therapy.

METHODS

We used the RIETE database to assess the prognostic value of d-dimer testing after discontinuing anticoagulation to identify patients at increased risk for recurrences. Transient risk factors were classified as major (postoperative) or minor (pregnancy, oestrogen use, immobilization or recent travel).

RESULTS

In December 2018, 1655 VTE patients with transient risk factors (major 460, minor 1195) underwent d-dimer measurements after discontinuing anticoagulation. Amongst patients with major risk factors, the recurrence rate was 5.74 (95% CI: 3.19-9.57) events per 100 patient-years in those with raised d-dimer levels and 2.68 (95% CI: 1.45-4.56) in those with normal levels. Amongst patients with minor risk factors, the rates were 7.79 (95% CI: 5.71-10.4) and 3.34 (95% CI: 2.39-4.53), respectively. Patients with major risk factors and raised d-dimer levels (n = 171) had a nonsignificantly higher rate of recurrences (hazard ratio [HR]: 2.14; 95% CI: 0.96-4.79) than those with normal levels. Patients with minor risk factors and raised d-dimer levels (n = 382) had a higher rate of recurrences (HR: 2.34; 95% CI: 1.51-3.63) than those with normal levels. On multivariate analysis, raised d-dimers (HR: 1.74; 95% CI: 1.09-2.77) were associated with an increased risk for recurrences in patients with minor risk factors, not in those with major risk factors.

CONCLUSIONS

Patients with raised d-dimer levels after discontinuing anticoagulant therapy for VTE provoked by a minor transient risk factor were at an increased risk for recurrences.

P4547Serum biochemical determinants of peripheral congestion assessed by bioimpedance vector analysis in acute heart failure

Background

The pathophysiology of peripheral congestion is poorly investigated in patients with acute heart failure (AHF).

Purpose

This study evaluated the relative contribution of serum colloid osmotic pressure (COP), relative plasma volume status (PVS), biomarkers of renal function, electrolytes, haemoglobin, and brain natriuretic peptide (BNP) in peripheral fluid overload using bioimpedance vector analysis (BIVA).

Methods

We retrospectively analysed data from 485 patients with AHF. Hydration status was evaluated by semiquantitative and quantitative approach using BIVA (R/Xc graph) and Hydration Index (HI), respectively. COP was calculated from albumin and total protein concentration, while relative PVS was calculated from validated equations.

Results

Congestion assessed by BIVA was observed in 304 (63%) patients and classified as mild (30%), moderate (42%), and severe (28%). On univariate analysis, HI was inversely correlated with COP (P<0.01), glomerular filtration rate (P<0.01), and haemoglobin (P<0.01), while positive correlations were found for relative PVS (P<0.05), BNP (P<0.01), and blood urea nitrogen (BUN; P<0.01). On stepwise multivariate analysis, COP explained 12% of the total variability, while BUN, PVS, haemoglobin, and BNP added a further 6%, 4%, 2%, and 1%, respectively, to the final explanatory model.

Conclusions

COP was the major determinant of the presence and entity of peripheral congestion assessed by BIVA. BUN, PVS, haemoglobin, and BNP revealed reduced influence on congestion as compared with COP. Routine laboratory testing could be useful in peripheral fluid accumulation. Future studies should evaluate the relationship between COP and pharmacological target therapies for the fluid management of AHF patients.

Acknowledgement/Funding

None

Prognosis of venous thromboembolism in orthopaedic surgery or trauma patients and use of thromboprophylaxis

BACKGROUND

There is scarce evidence about the prognosis of venous thromboembolism in patients undergoing orthopedic surgery and in patients suffering non-surgical trauma.

METHODS

We used the RIETE database (Registro Informatizado de pacientes con Enfermedad Trombo Embólica) to compare the prognosis of venous thromboembolism and the use of thromboprophylaxis in patients undergoing different orthopedic procedures and in trauma patients not requiring surgery.

RESULTS

From March 2001 to March 2015, a total of 61,789 patients were enrolled in RIETE database. Of these, 943 (1.52%) developed venous thromboembolism after elective arthroplasty, 445 (0.72%) after hip fracture, 1,045 (1.69%) after non-major orthopedic surgery and 2,136 (3.46%) after non-surgical trauma. Overall, 2,283 patients (50%) initially presented with pulmonary embolism. Within the first 90 days of therapy, 30 patients (0.66%; 95% CI 0.45-0.93) died from pulmonary embolism. The rate of fatal pulmonary embolism was significantly higher after hip fracture surgery (n = 9 [2.02%]) than after elective arthroplasty (n = 5 [0.53%]), non-major orthopedic surgery (n = 5 [0.48%]) or non surgical trauma (n = 11 [0.48%]). Thromboprophylaxis was more commonly used for hip fracture (93%) or elective arthroplasty (94%) than for non-major orthopedic surgery (71%) or non-surgical trauma (32%). Major bleeding was significantly higher after hip fracture surgery (4%) than that observed after elective arthroplasty (1.6%), non-major orthopedic surgery (1.5%) or non-surgical trauma (1.4%).

CONCLUSIONS

Thromboprophylaxis was less frequently used in lower risk procedures despite the absolute number of fatal pulmonary embolism after non-major orthopedic surgery or non-surgical trauma, exceeded that observed after high risk procedures.

Transmission and immunopathology of the avian influenza virus A/Anhui/1/2013 (H7N9) human isolate in three commonly commercialized avian species

H7N9 virus infection is a global concern, given that it can cause severe infection and mortality in humans. However, the understanding of H7N9 epidemiology, animal reservoir species and zoonotic risk remains limited. This work evaluates the pathogenicity, transmissibility and local innate immune response of three avian species harbouring different respiratory distribution of α2,6 and α2,3 SA receptors. Muscovy ducks, European quails and SPF chickens were intranasally inoculated with 10⁵ embryo infectious dose (EID)₅₀ of the human H7N9 (A/Anhui/1/2013) influenza isolate. None of the avian species showed clinical signs or macroscopic lesions, and only mild microscopic lesions were observed in the upper respiratory tract of quail and chickens. Quail presented more severe histopathologic lesions and avian influenza virus (AIV) positivity by immunohistochemistry (IHC), which correlated with higher IL-6 responses. In contrast, Muscovy ducks were resistant to disease and presented higher IFNα and TLR7 response. In all species, viral shedding was higher in the respiratory than in the digestive tract. Higher viral shedding was observed in quail, followed by chicken and ducks, which presented similar viral titres. Efficient transmission was observed in all contact quail and half of the Muscovy ducks, while no transmission was observed between chicken. All avian species showed viral shedding in drinking water throughout infection.

Outcome of Patients with Venous Thromboembolism and Factor V Leiden or Prothrombin 20210 Carrier Mutations During the Course of Anticoagulation

BACKGROUND

Individuals with factor V Leiden or prothrombin G20210A mutations are at a higher risk to develop venous thromboembolism. However, the influence of these polymorphisms on patient outcome during anticoagulant therapy has not been consistently explored.

METHODS

We used the Registro Informatizado de Enfermedad TromboEmbólica database to compare rates of venous thromboembolism recurrence and bleeding events occurring during the anticoagulation course in factor V Leiden carriers, prothrombin mutation carriers, and noncarriers.

RESULTS

Between March 2001 and December 2015, 10,139 patients underwent thrombophilia testing. Of these, 1384 were factor V Leiden carriers, 1115 were prothrombin mutation carriers, and 7640 were noncarriers. During the anticoagulation course, 160 patients developed recurrent deep vein thrombosis and 94 patients developed pulmonary embolism (16 died); 154 patients had major bleeding (10 died), and 291 patients had nonmajor bleeding. On multivariable analysis, factor V Leiden carriers had a similar rate of venous thromboembolism recurrence (adjusted hazard ratio [HR], 1.16; 95% confidence interval [CI], 0.82-1.64), half the rate of major bleeding (adjusted HR, 0.50; 95% CI, 0.25-0.99) and a nonsignificantly lower rate of nonmajor bleeding (adjusted HR, 0.66; 95% CI, 0.43-1.01) than noncarriers. Prothrombin mutation carriers and noncarriers had a comparable rate of venous thromboembolism recurrence (adjusted HR, 1.00; 95% CI, 0.68-1.48), major bleeding (adjusted HR, 0.75; 95% CI, 0.42-1.34), and nonmajor bleeding events (adjusted HR, 1.10; 95% CI, 0.77-1.57).

CONCLUSIONS

During the anticoagulation course, factor V Leiden carriers had a similar risk for venous thromboembolism recurrence and half the risk for major bleeding compared with noncarriers. This finding may contribute to decision-making regarding anticoagulation duration in selected factor V Leiden carriers with venous thromboembolism.

Lack of rivaroxaban influence on a prothrombinase-based assay for the detection of activated C protein resistance: an Italian ex vivo and in vitro study in normal subjects and factor V Leiden carriers

INTRODUCTION

Activated protein C resistance (APCr) leads to hypercoagulability and is due, often but not exclusively, to Factor V Leiden (FVL). The aim of this study was to assess the ex vivo and in vitro interference of the direct factor Xa inhibitor rivaroxaban (RIV) on a prothrombinase-based assay for APCr detection.

METHODS

An ex vivo study was performed on fresh plasma samples obtained from 44 subjects with FV wild-type and seven with FVL heterozygous, all treated with RIV. An in vitro study was performed on 15 plasma samples (six from normal subjects, six from heterozygous, and three from homozygous FVL carriers, all frozen specimens) spiked with RIV. RIV concentration was evaluated using a chromogenic assay, and APCr was evaluated by a prothrombinase-based assay.

RESULTS

No significant interference of RIV on APCr results obtained by a prothrombinase-based assay was observed for drug concentrations up to 400 ng/mL in FV wild-type and FVL carriers (homozygous and heterozygous). These results were confirmed both ex vivo and in vitro.

CONCLUSIONS

RIV did not significantly interfere with the prothrombinase-based assay used for the assessment of APCr, and this was observed to occur independently of FV status. However, only concentrations up to 400 ng/mL were tested and, therefore, what occurs in the presence of higher doses remains to be investigated.

The Clinical Course of Venous Thromboembolism May Differ According to Cancer Site

BACKGROUND

We hypothesized that the clinical course of venous thromboembolism in patients with active cancer may differ according to the specificities of primary tumor site.

AIM AND METHODS

We used data from RIETE (international registry of patients with venous thromboembolism) to compare the clinical venous thromboembolism-related outcomes during the course of anticoagulation in patients with one of the 4 more frequent cancers (breast, prostate, colorectal, or lung cancer).

RESULTS

As of September 2014, 3947 cancer patients were recruited, of whom 938 had breast, 629 prostate, 1189 colorectal, and 1191 lung cancer. Overall, 55% had metastatic disease (42%, 36%, 53%, and 72%, respectively). During the course of anticoagulant therapy (mean duration, 139 days), the rate of thromboembolic recurrences was similar to the rate of major bleeding in patients with breast (5.6 [95% confidence interval (CI), 3.8-8.1] vs 4.1 [95% CI, 2.7-5.9] events per 100 patient-years) or colorectal cancer (10 [95% CI, 7.6-13] vs 12 [95% CI, 9.4-15] per 100 patient-years). In contrast, in patients with prostate cancer, the rate of venous thromboembolic recurrences was half the rate of major bleeding (6.9 [95% CI, 4.4-10] vs 13 [95% CI, 9.2-17] events per 100 patient-years), whereas in those with lung cancer, the rate of thromboembolic recurrences was twofold higher than the rate of major bleeding (27 [95% CI, 22-23] vs 11 [95% CI, 8.6-15] per 100 patient-years).

CONCLUSIONS

Significant differences in the clinical profile of venous thromboembolic-related outcomes were observed according to the site of cancer. These findings suggest the development of cancer-specific anticoagulant strategies as an area for further research.

A prognostic score to identify low-risk outpatients with acute deep vein thrombosis in the lower limbs

BACKGROUND

No prior studies have identified which patients with deep vein thrombosis in the lower limbs are at a low risk for adverse events within the first week of therapy.

METHODS

We used data from the Registro Informatizado de la Enfermedad TromboEmbólica (RIETE) to identify patients at low risk for the composite outcome of pulmonary embolism, major bleeding, or death within the first week. We built a prognostic score and compared it with the decision to treat patients at home.

RESULTS

As of December 2013, 15,280 outpatients with deep vein thrombosis had been enrolled. Overall, 5164 patients (34%) were treated at home. Of these, 12 (0.23%) had pulmonary embolism, 8 (0.15%) bled, and 4 (0.08%) died. On multivariable analysis, chronic heart failure, recent immobility, recent bleeding, cancer, renal insufficiency, and abnormal platelet count independently predicted the risk for the composite outcome. Among 11,430 patients (75%) considered to be at low risk, 15 (0.13%) suffered pulmonary embolism, 22 (0.19%) bled, and 8 (0.07%) died. The C-statistic was 0.61 (95% confidence interval [CI], 0.57-0.65) for the decision to treat patients at home and 0.76 (95% CI, 0.72-0.79) for the score (P = .003). Net reclassification improvement was 41% (P < .001). Integrated discrimination improvement was 0.034 for the score and 0.015 for the clinical decision (P < .001).

CONCLUSIONS

Using 6 easily available variables, we identified outpatients with deep vein thrombosis at low risk for adverse events within the first week. These data may help to safely treat more patients at home. This score, however, should be validated.

Prognostic significance of tricuspid annular displacement in normotensive patients with acute symptomatic pulmonary embolism

BACKGROUND

Tricuspid annular plane systolic excursion (TAPSE) is an emerging prognostic indicator in patients with acute symptomatic pulmonary embolism (PE).

METHODS AND RESULTS

We prospectively examined 782 normotensive patients with PE who underwent echocardiography in a multicenter study. As compared with patients with a TAPSE of > 1.6 cm, those with a TAPSE of ≤ 1.6 cm had increased systolic pulmonary artery pressure (53.7 ± 16.7 mmHg vs. 40.0 ± 15.5 mmHg, P < 0.001), right ventricle (RV) end-diastolic diameter (3.5 ± 0.8 cm vs. 3.0 ± 0.6 cm, P < 0.001), and RV to left ventricle end-diastolic diameter ratio (1.0 ± 0.3 vs. 0.8 ± 0.2, P < 0.001), and a higher prevalence of RV free wall hypokinesis (68% vs. 11%, P < 0.001). Patients with a TAPSE of ≤ 1.6 cm at the time of PE diagnosis were significantly more likely to die from any cause (hazard ratio [HR] 2.3; 95% confidence interval [CI] 1.2-4.7; P = 0.02) and from PE (HR 4.4; 95% CI 1.3-15.3; P = 0.02) during follow-up. In an external validation cohort of 1326 patients with acute PE enrolled in the international multicenter Registro Informatizado de la Enfermedad TromboEmbólica, a TAPSE of ≤ 1.6 cm remained a significant predictor of all-cause mortality (HR 2.1; 95% CI 1.3-3.2; P = 0.001) and PE-specific mortality (HR 2.5; 95% CI 1.2-5.2; P = 0.01).

CONCLUSIONS

In normotensive patients with PE, TAPSE reflects right ventricular function. For these patients, TAPSE is independently predictive of survival.

Chemical vapor deposition of highly adherent diamond coatings onto co-cemented tungsten carbides irradiated by high power diode laser

The present investigation deals with the definition of a new eco-friendly alternative to pretreat Co-cemented tungsten carbide (WC-Co) substrates before diamond deposition by hot filament chemical vapor deposition (HFCVD). In particular, WC-5.8 wt %Co substrates were submitted to a thermal treatment by a continuous wave-high power diode laser to reduce surface Co concentration and promote the reconstruction of the WC grains. Laser pretreatments were performed both in N(2) and Ar atmosphere to prevent substrate oxidation. Diamond coatings were deposited onto the laser pretreated substrates by HFCVD. For comparative purpose, diamond coatings were also deposited on WC-5.8 wt %Co substrates chemically etched by the well-known two-step pretreatment employing Murakami's reagent and Caro's acid. Surface morphology, microstructure, and chemical composition of the WC-5.8 wt %Co substrates after the different pretreatments and the deposition of diamond coatings were assessed by surface profiler, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses. Wear performance of the diamond coatings was checked by dry sliding linear reciprocating tribological tests. The worn volume of the diamond coatings deposited on the laser pretreated substrates was always found lower than the one measured on the chemically etched substrates, with the N(2) atmosphere being particularly promising.

New limit on the lepton-flavor-violating decay μ+→e+γ

We present a new result based on an analysis of the data collected by the MEG detector at the Paul Scherrer Institut in 2009 and 2010, in search of the lepton-flavor-violating decay μ(+)e(+)γ. The likelihood analysis of the combined data sample, which corresponds to a total of 1.8×10(14) muon decays, gives a 90% C.L. upper limit of 2.4×10(-12) on the branching ratio of the μ(+)→e(+)γ decay, constituting the most stringent limit on the existence of this decay to date.

Clinical and ultrasound examination of the leeds enthesitis index in psoriatic arthritis and rheumatoid arthritis

Objective. To compare scores for the Leeds enthesitis index in psoriatic arthritis and rheumatoid arthritis using clinical assessment and ultrasonography (US). Design. Swelling and tenderness of the enthesis was assessed at six sites: lateral epicondyles of humerus (LE), medial condyles of femur (MC), and the insertion of the Achilles tendon (AT). US assessed “inflammatory activity” (power Doppler signal, oedema, tendon thickening, and bursal swelling) and “damage” (erosions and enthesophytes). Results. 94 patients were included, 71 with PsA and 23 with RA. The patients with RA were significantly older (PsA 47.6 years; RA 62.6 years; (mean difference in ages =15.0 years, 95% CI 9.3–20.7 years)). US scores were higher in RA at the LE, significantly so for the “damage” scores. No differences between RA and PsA were seen at the other sites. As a result, the odds ratio for PsA, given an US score above the median, was 0.41 (0.13–1.03). However, using the clinical score, the odds ratio for PsA was 2.16 (0.81–5.70). Conclusions. Although clinical scores of enthesitis are greater in PsA compared to RA, US enthesitis scores did not distinguish between RA and PsA. This may in part be due to more frequent juxta-articular involvement in RA and in part due to the older age of the subjects with RA.

Comparison between immunoradiometric and fluorimetric brain natriuretic peptide determination in patients with congestive heart failure

This study compared two different methods, namely the immunoradiometric (IRMA) and fluorimetric (FIA), in order to determine plasma brain natriuretic peptide (BNP) in congestive heart failure (CHF) patients.

METHODS

CHF in-patients underwent echocardiography and plasma BNP determination using both two methods. The echocardiograms analysed left ventricular end-systolic (LVESV) and end-diastolic (LVEDV) volumes and systolic dysfunction [left ventricular ejection fraction (LVEF) <50%].

RESULTS

Seventy-three (71% males, age 67 ± 9.6 yr) patients were enrolled, 31.5% affected by valvular heart disease. The mean LVEF was 39.8 ± 14.1%; in 26 (35%) a hypertensive etiology emerged. The immunoradiometric assay (IRMA) BNP was found to be significantly lower than the FIA determination 116.5 ± 149 pg/ml vs 267.3 ± 285.6 pg/ml; p=0.0001) and the two methods were closely correlated (r=0.89; p=0.00001). Logistic regression demonstrated a significant correlation between BNP, LVEF, and LVESV/LVEDV (r=-0.45, p=0.0003; r=-0.48, p=0.00001; r=0.22 p=0.003; r=0.34 p=0.0001; r=0.13 p=0.02; r=0.28 p=0.001 IRMA and FIA, respectively). IRMA BNP and FIA BNP significantly increased according to the worsening functional class [from 34.3 ± 60.2 pg/ml in NYHA (New York Heart Association) I to 555.5 ± 273.1 pg/ml in NYHA IV; from 86.1 ± 162.1 pg/ml in NYHA I to 1070 ± 42.2 pg/ml in NYHA IV, respectively]. In severe systolic dysfunction (LVEF<30%), receiver operating characteristic analysis revealed a satisfactorily sensitivity and specificity using a cut-off point of 50.6 pg/ml with IRMA and 243 pg/ml with FIA. In mild systolic dysfunction (LVEF<50%), a good sensitivity and specificity using a cut-off point of 42 pg/ml with IRMA and 182 pg/ml with FIA emerged.

CONCLUSIONS

In CHF patients both BNP methods correlated with NYHA class, LVEF, and ventricular volumes.

Prognostic role of B-type natriuretic peptide in patients with diabetes and acute decompensated heart failure

BACKGROUND

Several studies have reported the prognostic value of natriuretic peptides, but their predictive value in patients with diabetes mellitus is unknown. The aim of the study was to test the hypothesis that measurement of brain natriuretic peptide (BNP) levels in ambulatory patients with congestive heart failure (CHF) and diabetes can predict the occurrence of cardiovascular events at 6-month follow-up.

METHODS

We enrolled 145 consecutive patient with diabetes [age 72 +/- 9 years, hypertension (21%), ischaemic heart disease (52%), atrial fibrillation (22%), preserved left ventricular function (29%)] seen in the outpatient heart failure clinic after an acute episode of cardiac failure.

RESULTS

The median (25th/75th interquartile range) BNP concentrations at discharge were 186 (75-348) pg/ml. At 6-month clinical follow-up 10/145 (7%) subjects had died and 31/145 (21%) had been readmitted because of cardiac decompensation. BNP values of 200 and 500 pg/ml were found to have the best compromise between sensitivity (88 and 46%, respectively) and specificity (71 and 89%, respectively) for predicting events at 6 months. Multivariate Cox regression analysis identified only two parameters as predictors of events: serum creatinine [hazard ratio (HR) = 3.3; P = 0.02], and BNP plasma level BNP cut-off values (HR = 3.8; P = 0.03 for 201-499 pg/ml and HR = 7.7; P = 0.001 for > or = 500 pg/ml).

CONCLUSION

These results suggest that BNP and serum creatinine are strong predictors of clinical events in patients with diabetes and CHF. In these patients, clinical outcome might be stratified by plasma BNP levels.

Evaluation of investments in recycling centres for construction and demolition wastes in Brazilian municipalities

There are very few construction and demolition (C&D) waste recycling centres in Brazil. To encourage the building and operation of new units, data were collected and analysed relating to C&D waste management and recycling in Brazil. Based on the results of this analysis, a conceptual model is presented for conducting viability studies of future C&D waste recycling centres. Applying this model to verify the viability of private recycling centres, the results show that under current market conditions in Brazil, C&D waste recycling centres are not financially feasible based solely on revenue from the sale of processed products. Nevertheless, under the same market conditions, the recycling centres could be economically viable for public authorities depending on the particular circumstances of each municipality. The feasibility, however, depends on continuity and the production volume reached. The conceptual model, the results of its applications and the discussions about the experiences of existing centres can strongly support public authorities and private initiatives in their decision-making about investments in Brazil and in other developing countries.

Acute venous thromboembolism in patients with recent major bleeding. The influence of the site of bleeding and the time elapsed on outcome

BACKGROUND

Patients with major bleeding who subsequently develop clinically apparent venous thromboembolism (VTE) present a particularly difficult therapeutic dilemma.

METHODS

RIETE is a prospective registry of consecutive patients with symptomatic, objectively confirmed, acute VTE. We retrospectively studied those who had experienced recent major bleeding (<30 days prior to VTE) to assess the influence of the site of bleeding and the time elapsed to VTE on their 3 month outcome.

RESULTS

Of 12,294 patients enrolled up to July 2005, 306 (2.5%) had recent major bleeding: gastrointestinal (GI) tract, 116 (38%); intracranial, 94 (31%); other, 96 (31%). During the study period, 19 patients [6.2%; 95% confidence interval (CI) 3.5-8.9] with recent bleeding rebled (eight died): 13 of them (68%) during the first 2 weeks. Multivariate analysis confirmed that patients with recent GI bleeding had an increased risk for both major rebleeding (hazard ratio 2.8; 95% CI 1.4-5.3) and death (hazard ratio 1.9; 95% CI 1.2-3.1) compared to those with no recent bleeding. Those who bled in other sites had an increased risk only for death (hazard ratio 2.0; 95% CI 1.2-3.3). An elapsed time of <2 weeks from bleeding to the index VTE event was also associated with an increased risk for major rebleeding (hazard ratio 2.4; 95% CI 1.2-5.0) and death (hazard ratio 2.8; 95% CI 1.8-4.5).

CONCLUSION

The incidence of new bleeding or death depends on the site of prior bleeding and the time elapsed until VTE. This information may help to identify the best therapeutic approach for these high-risk patients.

The BNP assay does not identify mild left ventricular diastolic dysfunction in asymptomatic diabetic patients

AIMS

We examined the usefulness of BNP for screening for left ventricular (LV) diastolic dysfunction in a sample of type 2 diabetic patients, without structural heart disorder, who have never presented symptoms or signs of heart failure (HF).

METHODS AND RESULTS

Seventy-six consecutive patients admitted to the Outpatient Diabetes Clinic were studied. Blood samples were analyzed using the Triage BNP fluorescence immunoassay (Biosite Diagnostics, La Jolla, CA, USA). Echocardiography examinations were performed, with no knowledge of the BNP value. A total of 39 patients out of 76 (51%) were diagnosed with LV diastolic dysfunction and 23 (30%) with LV hypertrophy. Of the patients with LV diastolic dysfunction, impaired relaxation and pseudonormal pattern accounted for 97 and 3% of the cases, respectively. BNP levels among subjects with LV diastolic dysfunction (26+/-22 pg/ml, n=39) were not significantly different from patients with normal LV function (24+/-23 pg/ml, n=37 pg/ml; Mann-Whitney U-test, Z=-0.4, n.s.).

CONCLUSIONS

Our data confirm alarmingly high prevalence of LV diastolic dysfunction in asymptomatic individuals with diabetes. Identification of patients with preclinical diabetic cardiomyopathy should be a research and clinical priority. BNP levels cannot be used to detect mild LV diastolic dysfunction in this subset of patients, which requires Doppler echocardiography to be detected.

The outcome after treatment of venous thromboembolism is different in surgical and acutely ill medical patients. Findings from the RIETE registry

BACKGROUND

The history of venous thromboembolism (VTE), and the rationale for thromboprophylaxis in surgical patients are well understood. The situation is less clear for acutely ill medical patients.

OBJECTIVES

To compare the clinical presentation of VTE and clinical outcomes of immobile acutely ill medical patients with surgical patients.

PATIENTS

RIETE (Registro Informatizado de la Enfermedad TromboEmbolica) is a Spanish registry of consecutively enrolled patients with objectively confirmed, symptomatic acute VTE. In this analysis, clinical characteristics of patients, details of anticoagulant therapy, and outcomes of all enrolled acutely ill medical patients with immobility >/= 4 days, and surgical patients are included.

RESULTS

Of 6160 patients enrolled up to December 2003, 756 (12%) were acutely ill medical patients with immobility >/= 4 days, and 884 (14%) were surgical patients who developed VTE within 2 months of surgical intervention. Only 28% of acutely ill medical patients had received thromboprophylaxis, compared with 67% of surgical patients. During the 3-month follow-up period, both fatal pulmonary embolism (PE) and fatal bleeding occurred more frequently in acutely ill medical patients. Immobility in acutely ill medical patients, cancer, and PE were associated with a significantly higher risk of fatal PE or bleeding.

CONCLUSIONS

In patients treated for VTE, the incidences of fatal PE, fatal bleeding, and major bleeding were significantly higher in acutely ill medical patients compared with surgical patients. Given the low percentage of acutely ill medical patients who had received thromboprophylaxis, increasing its use appropriately may reduce the incidence of VTE and associated complications.

Ethnic differences in social network help-seeking strategies among Latino and Euro-Aamerican dementia caregivers

This research explores the help-seeking behavior of Euro-American and Latino caregivers who provide homecare assistance to an older adult with dementia. A community sample of 89 caregiver-care recipient pairs (39 Latino and 50 Euro-American) was interviewed. Descriptive, bivariate, and multivariate analyses were conducted to examine ethnic differences in use of an informal social network for help with caregiving tasks. Caregiver experiences that may impact help-seeking behaviors such as perceived availability of support network, satisfaction with support received and caregiver distress were also considered. Latino caregivers reported less help-seeking than did the Euro-American caregivers. Overall, ethnicity accounted for 16% of the variation in help-seeking behaviors. Ethnicity accounted for a significant portion of the variation in most of the help-seeking characteristics examined even after adjusting for socioeconomic variables. In the multivariate model, the effects of ethnicity on help-seeking persisted, while the effects of other likely predictors did not. The size of social network may not be synonymous with the seeking of support by caregivers. Likewise, higher levels of distress among Latino caregivers did not result in increased help-seeking behaviors. There remains a need to identity what other factors may contribute to the cultural variability in caregivers' use of informal support.

Cultural assessment in bioethical advocacy--toward cultural competency in bioethical practice

The continued diversification of the U.S. population poses increasing challenges for bioethical advocates (e.g., ethicists, physicians, nurses, social workers, psychologists, surrogates, researchers, and lawyers), especially those serving rapidly expanding and culturally varied populations. The issue from the bioethics perspective is that the members of ethnically diverse groups often bring different normative expectations and their own preferred decision-making formats to the bioethics table. For example, some advocates will encounter a "collectivity," or the family-as-a-whole rather than the individual, as a decision maker. In other instances, they may encounter cultural groups whose members (or some of whose members) will value the principle of beneficence more than personal autonomy. Moreover, such value-based challenges are likely to continue since forecasters predict that diversification will actually quicken in the United States throughout the next five decades. In the face of these changes in the bioethical climate, advocates must be prepared to strengthen their cultural assessment skills. Taking a multidimensional approach to the problem yields a four-point cultural assessment model to help advocates handle the great diversity of outlook and orientation among their culturally diverse clientele.

[Heart failure in nursing homes: prevalence, hospitalization, compliance to guidelines]

BACKGROUND

The prevalence of heart failure, the hospitalization rates for DRG 127 and the adherence to the recommendations included in the guidelines on pharmacological treatment among very old persons are poorly known.

METHODS

We screened 141 very old subjects (75% females, aged 87+/-4 years), living in 2 nursing homes. Heart failure was defined according to clinical criteria and on the basis of administrative databases and chart reviews. The latter were also used to collect data on hospitalization rates and pharmacological therapy.

RESULTS

We found that: 1) 23% of the subjects were affected by heart failure; 2) with regard to such patients, 26 hospital admissions for DRG 127 occurred in 1999 (18 admissions and 8 readmissions; 3) ACE-inhibitors have been prescribed to 54% of patients with a diagnosis of heart failure.

CONCLUSIONS

Heart failure affects a huge number of very old persons living in nursing homes. These patients have high hospitalization rates for DRG 127. The adherence to the recommendations included in the guidelines on the pharmacological therapy for very old persons is poor.

Poststreptococcal reactive arthritis in adults: long-term follow-up

BACKGROUND

Poststreptococcal reactive arthritis (PSReA) is a recognized inflammatory articular syndrome that follows group A streptococcal infection in persons not fulfilling the Jones criteria for the diagnosis of acute rheumatic fever. Characteristic features include nonmigratory arthritis, lack of response to aspirin or nonsteroidal anti-inflammatory agents, and the presence of extra-articular manifestations, including vasculitis and glomerulonephritis. Whether or not patients with PSReA develop carditis is a point of contention.

METHODS

We analyzed the clinical features, laboratory findings, response to therapy, and outcome in patients diagnosed with PSReA between 1983 and 1998 and observed through April 2000. All patients were contacted, reexamined, and repeat antistreptolysin, rheumatoid factor, C3 and C4 complement components, and echocardiograms were performed.

RESULTS

Seventeen patients (4 men and 13 women) were included. All were of low socioeconomic status. All patients had acute severe arthritis that began shortly after a sore throat episode. Extra-articular involvement including tenosynovitis, vasculitis, and glomerulonephritis was relatively common. More importantly, none exhibited clinical and/or echocardiographic evidence of cardiac involvement. Longterm antibiotic therapy was not given.

CONCLUSION

Cardiac involvement did not occur in this group of patients with PSReA. Prolonged prophylactic antibiotic therapy may not be required for adult patients presenting with PSReA.

Assessment of student performance in problem-based learning tutorial sessions

OBJECTIVES

To assess student performance during tutorial sessions in problem-based learning (PBL).

DESIGN

A 24-item rating scale was developed to assess student performance during tutorial sessions in problem-based learning (PBL) as conducted during the pre-clinical years of Medical School at the National Autonomous University of Mexico. Items were divided into three categories: Independent study, Group interaction and Reasoning skills. Fourteen tutors assessed 152 first and second-year students in 16 tutorial groups. An exploratory factor analysis with an Oblimin rotation was carried out to identify the underlying dimensions of the questionnaire.

SETTING

Medical School at the National Autonomous University of Mexico.

SUBJECTS

Medical students.

RESULTS

Factor analysis yielded four factors (Independent study, Group interaction, Reasoning skills, and Active participation) which together accounted for 76.6% of the variance. Their Cronbach reliability coefficients were 0.95, 0.83, 0.94 and 0. 93, respectively, and 0.96 for the scale as a whole.

CONCLUSIONS

It was concluded that the questionnaire provides a reliable identification of the fundamental components of the PBL method as observable in tutorial groups and could be a useful assessment instrument for tutors wishing to monitor students' progress in each of these components.

HLA-B27 subtypes in patients with ankylosing spondylitis (As) in Colombia

OBJECTIVE

We investigated the distribution of HLA-B27 subtypes in patients with ankylosing spondylitis (AS) belonging to two ethnic groups of Colombia.

MATERIAL AND METHODS

PCR-SSOs was used to detect the polymorphism in exons 2 and 3 of HLA-B27 in two groups of patients: 39 Mulattos and 20 Mestizos. Fifty-nine of them suffered of ankylosing spondylitis (AS), including two patients with ankylosing spondylitis plus anterior uveitis (AU). Only two out of eight HLA-B27 subtypes studied (B*2701-B*2708) were found.

RESULTS

The distribution of these alleles in the whole population was: B*2705: 87.1% and B*2702: 12.8% in the Mulattos group; 80% were B*2705 and 20% B*2702 in Mestizos group. The distribution of HLA-B27 subtypes was: 84.74% of patients with AS were B*2705 and 15.26% B*2702.

CONCLUSIONS

There was no significant difference in the distribution of HLA-B27 subtypes among the patients ethnic groups studied. Other authors have shown that B*2705, B*2702 and B*2704, the more frequent subtypes, are equally associated to the disease. Although population studies need to be done to analyze the distribution of subtypes between patients and controls, the low frequency of HLA-B27 within the normal population does not permit to do a representative number of controls; our results suggest that HLA-B*2705 and HLA-B*2702 are the subtypes more frequently associated with AS in patients from the two more prevalent patients ethnic groups in Colombia.

Characterization of MLH1 and MSH2 alternative splicing and its relevance to molecular testing of colorectal cancer susceptibility

The phenomenon of alternative splicing in the DNA mismatch repair genes MLH1 and MSH2 was extensively investigated by coupled reverse transcription-polymerase chain reaction in different human tissues, including 42 mononuclear blood cell samples--31 obtained from familial colon cancer patients or their at-risk relatives and 11 from healthy blood donors--7 normal colonic mucosae, 4 established human cancer cell lines, 8 colorectal tumors, and one sample each of ileum, liver, muscle, thymus, breast, and EBV-transformed lymphoblasts. Several isoforms were observed for each gene. Products of MLH1 alternative splicing included mRNAs lacking alternative exons 6/9, 9, 9/10, 9/10/11, 10/11, 12, 16, and 17. For MSH2, products lacking exons 5, 13, 2 through 7, and 2 through 8 were identified. The levels of expression were found to vary among different samples. All isoforms were found in a relevant fraction (43-100%) of the mononuclear blood cell samples, as well as in other tissues. The splicing variants were also detected in normal colonic mucosa, with the exceptions of the MLH1 -6/9 and -10/11 and the MSH2 -13 isoforms. Germline mutations of MLH1 and MSH2 confer constitutional predisposition to the development of colorectal cancer and other neoplasms. A substantial proportion of the mutations identified so far involve alterations of the normal splicing process. Knowledge of the existence of multiple alternative splicing events, not caused by genomic DNA changes, is important for the evaluation of the results of molecular diagnostic tests based on RNA analysis.

Loss of heterozygosity at the 5,10-methylenetetrahydrofolate reductase locus in human ovarian carcinomas

The high-affinity folate-binding protein (FBP) is primarily involved in the uptake of the 5-methyltetrahydrofolate, and its expression may be physiologically regulated by the intracellular folate content. The overexpression of FBP on the cell surface of ovarian carcinoma cells may be responsible for an increased folate uptake. We tested the hypothesis of the existence of a defect in the 5, 10-methylenetetrahydrofolate reductase (MTHFR) in ovarian tumours that could cause reduced intracellular regeneration of the 5-methyltetrahydrofolate and induce increased FBP expression. No sequence mutations were found in the MTHFR gene, but allelic deletions of this gene were frequently detected in ovarian tumours (59%). Chromosomal losses appeared to be confined to the 1p36.3 region to which the MTHFR gene maps. Although it cannot be stated that MTHFR is the target gene of the chromosomal loss involving the 1p36.3 region, a correlation between loss of heterozygosity at this locus and decrease in MTHFR activity was shown, suggesting a role of these allelic deletions in generating a biochemical defect in folate metabolism. Further studies are needed to assess further the relationship between MTHFR and FBP overexpression, but the demonstration of the alteration of a key metabolic enzyme of the folate cycle in a subset of human ovarian tumours is in accordance with the hypothesis of an altered folate metabolism in these neoplasias and might be exploited for therapeutic purposes.

Kinetic properties of erythrocyte Na+-Li+ and Na+-H+ exchange in hypertensive patients

OBJECTIVE

To ascertain the relationships between the kinetic properties of erythrocyte Na+-H+ exchange [maximum kinetic energy (Vmax), Michaelis constant (Km) for internal H+ and Hill's coefficient], Na+-Li+ (Vmax and Km for external Na+), and metabolic parameters in normotensive controls and hypertensive subjects.

MATERIALS AND METHODS

Na+-H+ exchange was measured as the Na+ influx driven by intracellular H+, and Na+-Li+ exchange as the Li+ efflux driven by extracellular Na+, in erythrocytes from normotensive (n = 59) and hypertensive (n = 93) subjects.

RESULTS

In comparison with normotensives, the hypertensives had a higher Vmax for Na+-Li+ and Na+-H+ exchange, a higher Km for external Na+ for Na+-Li+ exchange and a lower reduced Hill's number for Na+-H+ exchange. Vmax values for Na+-Li+ and Na+-H+ exchange were significantly correlated, as were Km values for internal H+ for Na+-H+ exchange and Km for external Na+ for Na+-Li+ exchange. Insulin resistance and beta-cell function indices were higher in the hypertensives than the normotensives. Upon stepwise multiple regression analysis, Vmax for Na+-Li+ exchange was correlated significantly and independently with Km for external Na+ and with the insulin resistance index, while Km for external Na+ was correlated with Km for internal H+, Vmax for Na+-H+ exchange and mean blood pressure. Vmax and Hill's coefficient for Na+-H+ exchange were correlated only with mean blood pressure.

CONCLUSIONS

The demonstration of functional correlations between the kinetic properties of Na+-H+ and Na+-Li+ exchange provides further evidence that erythrocyte Na+-Li+ exchange is a functioning mode of Na+-H+ exchange, which is affected by insulin resistance.