Risk scores' performance and their impact on operative decision-making in left-sided endocarditis: a cohort study

The accuracy of contemporary risk scores in predicting perioperative mortality in infective endocarditis (IE) remains controversial. The aim is to evaluate the performance of existent mortality risk scores for cardiovascular surgery in IE and the impact on operability at high-risk thresholds. A single-center retrospective review of adult patients diagnosed with acute left-sided IE undergoing surgery from May 2014 to August 2019 (n = 142) was done. Individualized risk calculation was obtained according to the available mortality risk scores: EuroScore I and II, PALSUSE, Risk-E, Costa, De Feo-Cotrufo, AEPEI, STS-risk, STS-IE, APORTEI, and ICE-PCS scores. A cross-validation analysis was performed on the score with the best area under the curve (AUC). The 30-day survival was 96.5% (95%CI 91-98%). The score with worse area under the curve (AUC = 0.6) was the STS-IE score, while the higher was for the RISK-E score (AUC = 0.89). The AUC of the majority of risk scores suggested acceptable performance; however, statistically significant differences in expected versus observed mortalities were common. The cross-validation analysis showed that a large number of survivors (> 75%) would not have been operated if arbitrary high-risk threshold estimates had been used to deny surgery. The observed mortality in our cohort is significantly lower than is predicted by contemporary risk scores. Despite the reasonable numeric performance of the analyzed scores, their utility in judging the operability of a given patient remains questionable, as demonstrated in the cross-validation analysis. Future guidelines may advise that denial of surgery should only follow a highly experienced Endocarditis Team evaluation.

Infective endocarditis in diabetic patients: a different profile with prognostic

Background

Infective Endocarditis (IE) is a severe condition. Diabetes mellitus (DM) has been associated with a poor prognosis in other settings. Our aim was to describe the profile and prognosis of IE with and without DM and to analyse the prognostic relevance of DM-related organ damage.

Methods

Retrospective analysis of the Spanish IE Registry (2008–2020).

Results

The cohort comprises 5.590 IE patients with a mean age of 65.0±15.5 years, 3.764 (67.3%) were male. DM was found in 1.625 patients (29.1%) and 515 presented DM-related organ damage. DM prevalence during the first half of the study period was 27.6% vs. 30.6% in the last half, p=0.015. Patients with DM presented higher in-hospital mortality than those without DM (521 [32.1%] vs 924 [23.3%] p<0.001) and higher one-year mortality (640 [39.4%] vs 1.131 [28.5%] p<0.001). Among DM patients, organ damage was associated with higher in-hospital (200 [38.8%] vs 321 [28.9%], p<0.001) and one-year mortality (247 [48.0%] vs 393 [35.4%], p<0.001). Multivariate analyses showed an independent association of DM with in-hospital (odds ratio [OR] = 1.34, 95% confidence interval [CI]: 1.16–1.55, p<0.001) and one-year mortality (OR = 1.38, 95% CI: 1.21–1.59, p<0.001). Among DM patients, organ damage was independently associated with higher in-hospital (OR = 1.37, 95% CI: 1.06–1.76, p=0.015) and one-year mortality (OR=1.59, 95% CI: 1.26–2.01, p<0.001)

Conclusions

The prevalence of DM among patients with IE is increasing and is already above 30%. DM is independently associated with a poor prognosis, particularly in the case of DM with organ damage.

Funding Acknowledgement

Type of funding sources: None.

Phenotyping calcium and contraction in a zebrafish model of phospholamban R9C mutation

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Science, Innovation and Universities, Spain by Consejería de Educación, Cultura y Deportes. Junta de Comunidades de Castilla-La Mancha.

Background

Phospholamban regulates SERCA2a pump activity by reducing its calcium affinity in the heart. Under β-adrenergic stimulation, protein kinase A (PKA) phosphorylates phospholamban attenuating its inhibitory effect on SERCA2a. The phospholamban mutation Arg 9 to Cys (R9C) was firstly identified in an American family with ventricular dilatation and premature death, and subsequently in a cohort of dilated cardiomyopathy patients in South Africa. Emerging evidence suggests that phospholamban R9C is a loss-of-function mutation with autosomal dominant inheritance. In vitro studies revealed that it enhances pentamer assembly by disulfide bridge formation, reducing the availability of phospholamban monomers to regulate SERCA2a.

Purpose

The present study aimed to investigate defects in Ca2+ handling and cardiac function of phospholamban R9C mutation in an in vivo zebrafish model.

Methods

We generated transgenic zebrafish lines overexpressing phospholamban wild-type (TgPLNwt) and phospholamban R9C (TgPLNR9C) in the heart of zebrafish. To measure calcium kinetics in 3 day-old larvae, TgPLNwt and TgPLNR9C fish were outcrossed with transgenic zebrafish lines expressing the fluorescent calcium biosensor mCyRFP1-GCaMP6f (TgRFP-GcaMP6f) and the bioluminescence calcium biosensor GFP-Aequorin (TgGA) in the heart.

Results

Overexpression of phospholamban wild-type and R9C did not alter the heart rate compared to sibling larvae, and no differences were observed in the upstroke and recovery time of the calcium transients.  However, atrial and ventricular calcium transient amplitude were higher in TgPLNR9C larvae with respect to TgPLNwt larvae. Contractile force of the heart, assessed as the fractional shortening, increased in TgPLNR9C larvae compared to siblings and TgPLNwt. Furthermore, stroke volume and cardiac output were also higher in TgPLNR9C larvae. Bioluminescence experiments were performed to estimate the average calcium levels in the heart. We found that TgPLNR9C larvae showed higher calcium levels than sibling and TgPLNwt larvae. To evaluate the responsiveness to β-adrenergic stimulation, larvae were treated with the β-agonist isoproterenol. Calcium transient amplitude and contractile force increased in sibling and TgPLNwt larvae after treatment. However, this response was absent in TgPLNR9C larvae, suggesting that they were hyper-stimulated in basal conditions, displaying amplitude and contractile force similar to sibling and TgPLNwt larvae treated with isoproterenol.

Conclusion

TgPLNR9C larvae exhibited aberrant calcium handling in the heart with higher calcium levels and contractility, consistent with a lack of inhibition of SERCA2a. Consequently, TgPLNR9C larvae did not respond to β-adrenergic stimulation. These results were consistent with previous in vitro studies carried out in cardiomyocites infected with phospholamban R9C and highlighted the pathological defects of phospholamban R9C at early stages of the disease.

Calcium, contraction, and hemodynamic alterations induced by arrhythmogenic drugs in the zebrafish larvae

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): MCIN/AEI/ 10.13039/501100011033 and “ERDF A way of making Europe” by the European Union

Background

Ca2+ ion is pivotal in excitation-contraction coupling. The dysregulation of Ca2+ fluxes is at the core of inherited and acquired arrhythmias. In recent years zebrafish have become an attractive vertebrate model to study heart development, cardiotoxicity, and heart diseases. We recently reported that the transgenic zebrafish line Tg(myl7:Twitch-4) expressing the ratiometric Ca2+ indicator Twitch-4 in the heart, allowed imaging Ca2+ transients (CaT) simultaneously with heart contraction in zebrafish larvae, thus maintaining the physiological mechano-electrical feedback.

Purpose

This study aimed to detect subtle disturbances in Ca2+ cycling, contractility, and hemodynamics induced by arrhythmogenic drugs in zebrafish larvae.

Methods

We have used the zebrafish transgenic line Tg(myl7:Twitch-4) and a custom software to acquire and analyze fluorescence emission ratio images of the heart. Larvae of 3- and 5-days post-fertilization (dpf) were incubated with arrhythmogenic drugs, and their effects on the systolic and diastolic Ca2+ and the CaT amplitude in the atrium and ventricle were determined. As the ventricular diameter was assessed in the same fluorescence images, a simultaneous, real-time, measurement of contraction correlated with Ca2+ was obtained. The systolic and diastolic areas, measured independently, were used to estimate hemodynamic parameters.

Results

Dofetilide caused time-dependent bradycardia and ultimately a 2:1 arrhythmia in 3 and 5 dpf larvae, with an increase in the CaT amplitude. the ejection fraction and the stroke volume increased, but the cardiac output decreased due to the low heart rate (2:1 arrhythmia). The T-type Ca2+ channel antagonist ML218 induced bradycardia and decreased systolic and diastolic Ca2+ levels in 3 dpf larvae, but the CaT amplitude did not change. Interestingly, some larvae (3 out of 14) displayed a progressive lengthening of the time between the start of atrial and ventricular CaT, analogous to increased PR interval of the electrocardiogram, until a ventricular systole failed. This is reminiscent of a second-degree atrioventricular block in humans. At higher ML218 concentration, a 2:1 arrhythmia was observed and increased ventricular CaT amplitude in all larvae.

Conclusions

We characterized Ca2+ changes induced by arrhythmogenic drugs and correlated them with contractility and hemodynamic parameters. The zebrafish line Tg(myl7:Twitch-4) allowed investigating drug-induced arrhythmias in this animal model with unprecedented detail. This transgenic line will serve to screen cardiotoxicity during drug development and to study conduction and rhythm defects in zebrafish, and their correlation with human disease.

Complementary techniques (spICP-MS, TEM, and HPLC-ICP-MS) reveal the degradation of 40 nm citrate-stabilized Au nanoparticles in rat liver after intraperitoneal injection

BACKGROUND

Due to the increased use of engineered nanoparticles (NPs), their tracing in environmental and biological systems is of utmost importance. Besides their accumulation within a biological specimen, little is known about their degradation and transformation into corresponding low-molecular species that might influence any toxicological impact.

ANALYTICAL METHODS

Wistar rats underwent intraperitoneal injections of 40 nm citrate-stabilized gold nanoparticles. Different liver samples were analysed for the occurrence of nanoparticles and potential degradation products by means of spICP-MS, TEM and HPLC-ICP-MS.

MAIN FINDINGS

Studies using spICP-MS revealed the presence of the originally administrated Au NPs (40 nm diameter) and some evidences of other Au-containing species due to the increased background signal. Images obtained by transmission electron microscopy (TEM) showed the predominant presence of particles of significantly smaller diameter (6 ± 2 nm). As complementary method, HPLC-ICP-MS confirmed the presence of both particle types indicating a degradation of the Au NPs accompanied by detection of low-molecular Au species.

CONCLUSIONS

This study underlines that degradation of gold nanoparticles to low-molecular gold species might have to be taken into account in future for studies on their toxicological behaviour and their potential use in clinical applications.

Early in vitro development of daptomycin non-susceptibility in high-level aminoglycoside-resistant Enterococcus faecalis predicts the efficacy of the combination of high-dose daptomycin plus ampicillin in an in vivo model of experimental endocarditis

Background

Previous studies showed development of daptomycin non-susceptibility (DNS: MIC >4 mg/L) in Enterococcus faecalis infections. However, no studies have assessed the efficacy of the combination of daptomycin/ampicillin against E. faecalis strains developing DNS in the experimental endocarditis (EE) model.

Objectives

To assess the in vitro and in vivo efficacy of daptomycin at 10 mg/kg/day, daptomycin/ampicillin and ampicillin/ceftriaxone against two high-level aminoglycoside-resistant E. faecalis strains, one developing DNS after in vitro exposure to daptomycin and another that did not (DS).

Methods

Subculture of 82 E. faecalis strains from patients with endocarditis with daptomycin MICs, time-kill and in vivo experiments using the EE model.

Results

33% of the strains (27 of 82) displayed DNS after subculture with daptomycin. Daptomycin MIC rose from 0.5-2 to 8-16 mg/L. In time-kill experiments, when using a high inoculum (10 8 cfu/mL), daptomycin/ampicillin was synergistic for one-third of DS strains and none of DNS strains, while ampicillin/ceftriaxone retained synergy in all cases. In the EE model, daptomycin did not significantly reduce cfu/g from vegetations compared with control against either strain, while daptomycin/ampicillin reduced significantly more cfu/g than daptomycin against the DS strain, but not against the DNS strain [2.9 (2.0-4.1) versus 6.1 (4.5-8.0); P  =   0.002]. Ampicillin/ceftriaxone was synergistic and bactericidal against both strains, displaying the same activity as daptomycin/ampicillin against the DS strain.

Conclusions

Performance of an Etest for daptomycin MIC after subculture with daptomycin inhibitory doses on strains of high-level aminoglycoside-resistant E. faecalis endocarditis may be an easy test to predict the in vivo efficacy of daptomycin/ampicillin.

The associations between physical fitness and cardiometabolic risk and body-size phenotypes in perimenopausal women

OBJECTIVE

To study the association between physical fitness and body-size phenotypes, and to test which aspects of physical fitness show the greatest independent association with cardiometabolic risk in perimenopausal women.

STUDY DESIGN

This cross-sectional study involved 228 women aged 53±5years from southern Spain.

MAIN OUTCOME MEASUREMENTS

Physical fitness was assessed by means of the Senior Fitness Test Battery (additionally including handgrip strength and timed up-and-go tests). Anthropometry, resting heart rate, blood pressure and plasma markers of lipid, glycaemic and inflammatory status were measured by standard procedures. The harmonized definition of the 'metabolically healthy but obese' (MHO) phenotype was employed to classify individuals.

RESULTS

The overall prevalence of the MHO phenotype was 13% but was 43% among the obese women. Apart from traditional markers, metabolically healthy non-obese women had lower levels of C-reactive protein than women with the other phenotypes (p<0.001), and levels of glycosylated haemoglobin were lower in MHO women than in metabolically abnormal non-obese women (overall p=0.004). Most of the components of physical fitness differed with body-size phenotypes. The 6-min walk and the back-scratch tests presented the most robust differences (both p<0.001). Moreover, the women's performance on the back-scratch (β=0.32; p<0.001) and the 6-min walk (β=0.22; p=0.003) tests was independently associated with the clustered cardiometabolic risk. The back-scratch test explained 10% of the variability (step 1, p<0.001), and the final model, which also included the 6-min walk test (step 2, p=0.003), explained 14% of the variability.

CONCLUSION

Low upper-body flexibility was the most important fitness indicator of cardiometabolic risk in perimenopausal women, but cardiorespiratory fitness also played an important role.

Enterococcal endocarditis revisited

The Enterococcus species is the third main cause of infective endocarditis (IE) worldwide, and it is gaining relevance, especially among healthcare-associated cases. Patients with enterococcal IE are older and have more comorbidities than other types of IE. Classical treatment options are limited due to the emergence of high-level aminoglycosides resistance (HLAR), vancomycin resistance and multidrug resistance in some cases. Besides, few new antimicrobial alternatives have shown real efficacy, despite some of them being recommended by major guidelines (including linezolid and daptomycin). Ampicillin plus ceftriaxone 2 g iv./12 h is a good option for Enterococcus faecalis IE caused by HLAR strains, but randomized clinical trials are essential to demonstrate its efficacy for non-HLAR EFIE and to compare it with ampicillin plus short-course gentamicin. The main mechanisms of resistance and treatment options are also reviewed for other enterococcal species.

Interaction between orexin A and cannabinoid system in the lateral hypothalamus of rats and effects of subchronic intraperitoneal administration of cannabinoid receptor inverse agonist on food intake and the nutritive utilization of protein

Crosstalk may occur between cannabinoids and other systems controlling appetite, since cannabinoid receptors are present in hypothalamic circuits involved in feeding regulation, and likely to interact with orexin. In this study, an immunohistochemical approach was used to examine the effect of the intracerebroventricular administration of cannabinoid receptor inverse agonist AM 251 on orexin neuropeptide in the hypothalamic system. AM-activated neurons were identified using c-Fos as a marker of neuronal activity. The results obtained show that AM 251 decreases orexin A immunoreactivity, and that it increases c-Fos-immunoreactive neurons within the hypothalamus when compared with the vehicle-injected control group. We also studied the effects of subchronic intraperitoneal administration of AM 251 on food intake, body weight, and protein utilization. The administration of AM 251 at 1, 2, or 5 mg/kg led to a significant reduction in food intake, along with a significant decrease in the digestive utilization of protein in the groups injected with 1 and 2 mg/kg. There was a dose-related slowdown in weight gain, especially at the doses of 2 and 5 mg/kg, during the initial days of the trial. The absence of this effect in the pair-fed group reveals that any impairment to digestibility was the result of administering AM 251. These data support our conclusion that hypothalamic orexigenic neuropeptides are involved in the reduction of appetite and mediated by the cannabinoid receptor inverse agonist. Furthermore, the subchronic administration of AM 251, in addition to its effect on food intake, has significant effects on the digestive utilization of protein.

Efficacy and safety of fosfomycin plus imipenem as rescue therapy for complicated bacteremia and endocarditis due to methicillin-resistant Staphylococcus aureus: a multicenter clinical trial

BACKGROUND

There is an urgent need for alternative rescue therapies in invasive infections caused by methicillin-resistant Staphylococcus aureus (MRSA). We assessed the clinical efficacy and safety of the combination of fosfomycin and imipenem as rescue therapy for MRSA infective endocarditis and complicated bacteremia.

METHODS

The trial was conducted between 2001 and 2010 in 3 Spanish hospitals. Adult patients with complicated MRSA bacteremia or endocarditis requiring rescue therapy were eligible for the study. Treatment with fosfomycin (2 g/6 hours IV) plus imipenem (1 g/6 hours IV) was started and monitored. The primary efficacy endpoints were percentage of sterile blood cultures at 72 hours and clinical success rate assessed at the test-of-cure visit (45 days after the end of therapy).

RESULTS

The combination was administered in 12 patients with endocarditis, 2 with vascular graft infection, and 2 with complicated bacteremia. Therapy had previously failed with vancomycin in 9 patients, daptomycin in 2, and sequential antibiotics in 5. Blood cultures were negative 72 hours after the first dose of the combination in all cases. The success rate was 69%, and only 1 of 5 deaths was related to the MRSA infection. Although the combination was safe in most patients (94%), a patient with liver cirrhosis died of multiorgan failure secondary to sodium overload. There were no episodes of breakthrough bacteremia or relapse.

CONCLUSIONS

Fosfomycin plus imipenem was an effective and safe combination when used as rescue therapy for complicated MRSA bloodstream infections and deserves further clinical evaluation as initial therapy in these infections.

Evaluation of the biological effect of Ti generated debris from metal implants: ions and nanoparticles

Metallic implants placed in humans exhibit wear and corrosion that result in the liberation of metal-containing by-products.

Influence of low-protein dietetic foods consumption on quality of life and levels of B vitamins and homocysteine in patients with chronic renal failure

OBJECTIVE

The aim of the study was to determine whether the consumption of low protein dietetic foods improved the quality of life and nutritional status for vitamins B and homocysteine in patients with chronic renal failure.

METHODOLOGY

This nutritional-intervention involved 28 men and 21 women, divided into two groups. The control-group consumed a low-protein diet prescribed, and the experimental-group consumed a diet in which some commonly used foods were replaced by low-protein dietetic foods. The study lasted 6 months. Food consumption was assessed by 24-h recall. Vitamin B6 as alphaEAST was measured in blood. Creatinine, urea, vitamin B12, folate and homocysteine were measured in plasma. The impact on the patients' quality of life from consuming the dietetic foods was assessed via the SF-36 questionnaire.

RESULTS

After 6 months, the protein intake among the experimental-group had decreased by 40%, and the urea/creatinine ratio and alphaEAST activity were also lower. The results of the SF-36 questionnaire show that the patients in the experimental-group obtained higher scores in the categories of general health and physical status.

CONCLUSIONS

The dietetic foods were very well accepted by all patients and their use allowed a better control of the protein intake, improved B6 status and a better quality of life.

[Vitamin B complex and homocysteine in chronic renal failure]

Metabolic, biochemical, and hormonal changes occur in chronic renal failure usually associated with hyponutrition states. In predialysis patients, knowing the nutritional state about water-soluble vitamins such as thiamine, riboflavin, pyridoxine, cianocobalamine, and folic acid is becoming more and more important since some of the manifestations of chronic renal failure may be due to the deficiency of some of these water-soluble vitamins. The metabolic pathways in which most of these vitamins participate are interrelated and it is difficult to understand how the individual deficits of each vitamin affect renal pathology. This work aims at reviewing not only this issue but also the status of these water-soluble vitamins that different authors have found in groups of predialysis patients. On the other hand, the issue on the high prevalence of hyperhomocysteinemia in chronic renal failure as the main mortality risk factor due to cardiovascular pathologies as well as the implication of these vitamins in the metabolism of homocysteine, and consequently in plasma levels of this metabolite in predialysis patients is reviewed.

Magnetic properties of ZnO nanoparticles

We experimentally show that it is possible to induce room-temperature ferromagnetic-like behavior in ZnO nanoparticles without doping with magnetic impurities but simply inducing an alteration of their electronic configuration. Capping ZnO nanoparticles ( approximately 10 nm size) with different organic molecules produces an alteration of their electronic configuration that depends on the particular molecule, as evidenced by photoluminescence and X-ray absorption spectroscopies and altering their magnetic properties that varies from diamagnetic to ferromagnetic-like behavior.

[Nutrients and energy intake assessment in the critically ill patient on enteral nutritional therapy]

INTRODUCTION AND OBJECTIVES

The critically ill patient is especially susceptible to malnutrition due to his/her hypermetabolic state that leads to an increase in the nutritional requirementes, which many times are not compensated with the administered enteral formulas. The assessment of nutritional intake is essential in this kind of patients to know to what level their energetic and nutritional requirements are fulfilled, improving and monitoring in the most individualized possible way to indicated clinical and nutritional therapu.

METHODOLOGY

This is a retrospective study in which all patients admitted to the Intensive Care Unit of Virgen de las Nieves Hospital were studied from January to December of 2003, aged more than 18 years, and on enteral nutrition. A total of 90 patients (52 men and 38 women) were studied, 81% of which were older than 50 years, and 57% had hospital stays longer than 8 days, with a 21% mortality rate. Intake was assessed from time of admission and throughout the whole hospitalization period. Energetic requirements were calculated according to the modified Long's formula and micronutrients intakes were compared to existing general recommendations for the Spanish, European and American populations, and to vitaminic requirements in critically ill patients.

RESULTS

Percentages of mean energy and nutrients intakes in relation to theoretical calculated requirements for both genders are presented in figure 1. Mean energy intake was 1,326 cal in men and 917 cal in women. With regards to micronutrients intake, the values found for proteins, falts, and carbohydrates were lower than 50% of the requirements for both genders. The percentage of adequacy as referred to requirements for vitamins and minerals intake is shown in figure 2. Reference recommendations used correspond to sufficient intakes to cover the healthy individual requirements, therefore, the values obtained in our study show and adequacy greater than 75%, with the exception of particular elements such as vitamin A and magnesium. However, by taking a look at figure 3, which shows the adequacy of vitamins intake at recommended does for sick patients, the intake is lower than 25% of the requirements in all cases, and these deficiencies significantly interfere with wound healing, the immune, cardiovascular and nervous systems, as well as with metabolism of the remaining macronutrients leading to an unbalanced situation of the antioxidant system, worsening the patient's clinical status.

CONCLUSIONS

The present study confirms the need for monitoring individually the nutritional requirements in the critically ill patient and adapting recommendations to his/her metabolic changes, since currently these recommendations are not clearly defined for these situations. It is necessary to provide micronutrients doses closer to the patient's demands, so that the nutritional status and the balance of the antioxidant system may be preserved or improved, making the adopted clinical treatment more effective.

Assessment of thiamin (vitamin B1) and riboflavin (vitamin B2) status in an adult Mediterranean population

The aim of the present study was to assess the nutritional status for thiamin (vitamin B1) and riboflavin (vitamin B2) in an adult Mediterranean population, in order to identify patterns of intake, groups at risk for deficiency and factors that might influence this risk. A cross-sectional survey was carried out in Andalusia, a western Mediterranean region in southern Spain. Nutrient intakes were studied in a random sample of 3390 subjects (1746 men, 1644 women) who were between 25 and 60 years of age. Blood samples were obtained for biochemical assays in a random subsample of 372 subjects (181 men, 191 women). Food consumption was assessed by 48 h recall. Vitamin B1 and B2 were measured as erythrocyte transketolase and as erythrocyte glutathione reductase activation coefficients, respectively. Energy and vitamin intakes were significantly higher in men than in women. Intakes were below two-thirds of the recommended dietary allowance for vitamin B1 in 7.80 % of the men and 4.50 % of the woman, and were below this level for vitamin B2 in 18.00 % of the men and 11.70 % of the women. Age, educational level, alcohol use and smoking were also associated with differences in the intake of these nutrients. Biochemical analyses showed that vitamin B1 and B2 status was deficient in 6.40 and 5.30 % of the population, respectively. Although factors such as gender, age, level of education, drinking and smoking can have an effect on the risk of inadequate intake of these nutrients, these factors did not affect biochemical indices of nutritional status in the present study.

Vitamins B6 and B12 and folate status in an adult Mediterranean population

OBJECTIVE

To assess the nutritional status for vitamins B(6) and B(12) and folate in an adult Mediterranean population, in order to identify patterns of intake, groups at risk for deficiency, and factors that might influence this risk.

DESIGN

A cross-sectional epidemiological survey.

SETTING

Andalusia, a western Mediterranean region in southern Spain.

SUBJECTS

The study was carried out with a random sample of 3528 subjects (1813 men, 1715 women) who were between 25 and 60 y of age. Blood samples were obtained for biochemical assays in a random subsample of 384 subjects (183 men, 201 women).

INTERVENTIONS

Food consumption was assessed by 48-h recall. Vitamin B(6) was measured as alpha erythrocyte aspartate aminotransferase activation coefficient (alphaEAST); vitamin B(12) and folate concentrations were measured in plasma.

RESULTS

Energy and vitamin intakes were significantly higher in men than in women. In men, intakes were below two-thirds of the RDA in 10.8, 2.9 and 22.6% for B(6), B(12) and folate, respectively. The corresponding figures in women were 16.7, 5.1 and 23.5% for vitamins B(6), B(12) and folate. Age, place of residence and educational level, alcohol use and smoking were also associated with differences in the intake of these nutrients. Biochemical analyses showed that vitamins B(6), B(12) and folate status was acceptable in 75.7, 89.1 and 57.6% of the population, respectively. Plasma concentration of folate was significantly higher in women.

CONCLUSION

Our results provide a precise estimate of the nutritional status for vitamins B(6), B(12) and folate in the adult population of southern Spain. Factors such as age, place of residence, level of education and smoking can increase the risk of inadequate intake of some nutrients. However, these factors did not affect biochemical indexes of nutritional status in the present study.

SPONSORSHIP

Dirección General de Salud Pública and the Health Council of the Andalusian Regional Government.

Vitamins in Spanish food patterns: the eVe Study

OBJECTIVE

To describe vitamin intakes in Spanish food patterns, identify groups at risk for inadequacy and determine conditioning factors that may influence this situation.

DESIGN

Pooled-analysis of eight cross-sectional regional nutrition surveys.

SUBJECTS

Ten thousand two hundred and eight free-living subjects (4728 men, 5480 women) aged 25-60 years. Respondents of population nutritional surveys carried out in eight Spanish regions (Alicante, Andalucia, Balearic Islands, Canary Islands, Catalunya, Galicia, Madrid and Basque Country) from 1990 to 1998. The samples were pooled together and weighted to build a national random sample.

METHODS

Dietary assessment by means of repeated 24-hour recall using photograph models to estimate portion size. Adjusted data for intra-individual variation were used to estimate the prevalence of inadequate intake. A Diet Quality Score (DQS) was computed considering the risk for inadequate intake for folate, vitamin C, vitamin A and vitamin E. DQS scores vary between 0 (good) and 4 (very poor). Influence of lifestyle (smoking, alcohol consumption and physical activity) was considered as well.

RESULTS

Inadequate intakes (<2/3 Recommended Dietary Intake) were estimated in more than 10% of the sample for riboflavin (in men), folate (in women), vitamin C, vitamin A, vitamin D and vitamin E. More than 35% of the sample had diets classified as poor quality or very poor quality. Factors identified to have an influence on a poor-quality diet were old age, low education level and low socio-economical level. A sedentary lifestyle, smoking, usual consumption of alcohol and being overweight were conditioning factors for a poor-quality diet as well.

CONCLUSION

Results from The eVe Study suggest that a high proportion of the Spanish population has inadequate intakes for at least one nutrient and nearly 50% should adjust their usual food pattern towards a more nutrient-dense, healthier diet.

Alcohol consumption and academic performance in a population of Spanish high school students

OBJECTIVE

The present study was designed to identify patterns of alcohol consumption among Spanish high school students and describe the relationship between alcohol intake and school performance.

METHOD

The sample population consisted of students, aged 14 to 19 years, who were attending high school during the academic year 1994-95 in the city of Granada in southern Spain. We studied 1,602 (861 female) students (alpha error - 0.05, sampling error = 5%), using a self-administered questionnaire that contained items about individual and family demographics, quantity and frequency of alcohol consumption, and school performance. Total alcohol consumption was recorded as grams (g) of alcohol per week and per day for three categories of alcoholic drinks: wine, beer and distilled spirits.

RESULTS

The percentage of nondrinkers was 21.05% for male adolescents and 28.56% for female adolescents. The mean amount of alcohol consumed per week was larger in male than in female students (F= 18.36, l/l,594 df, p < .001) and distilled spirits accounted for the largest proportion of alcohol consumed. No significant differences in drinking patterns were found between students at public and private schools. The risk of academic failure increased considerably when more than 150 g of alcohol were consumed per week (OR: 2.91; 95% CI: 1.94-4.43).

CONCLUSIONS

Although we cannot draw any conclusions about the causes of the association between academic failure and teenage drinking, our results do show that the risk of failing increases together with alcohol intake. However, it should be noted that academic achievement is also influenced by many factors other than alcohol consumption.

High-grade prostate intraepithelial neoplasia shares cytogenetic alterations with invasive prostate cancer

BACKGROUND

High-grade prostate intraepithelial neoplasia (PIN) is the most likely precursor of prostate adenocarcinoma. However, the relationship between this lesion and prostate cancer has not yet been established. The detection of cytogenetic changes in the lesions prior to prostate adenocarcinoma would be useful in demonstrating such a pathogenic relationship.

METHODS

Twenty eight high-grade PIN cases were found among 57 specimens of radical prostatectomy performed for clinically localized prostate cancer. Fluorescence in situ hybridization (FISH) analysis using centromeric probes to enumerate chromosomes 7, 8, 10, and 12 was performed to study the numerical chromosome alterations. FISH analysis was carried out over isolated nuclei obtained from high-grade PIN areas and prostate cancer foci in the same prostatectomy specimen.

RESULTS

Of the 28 suitable cases it was possible to complete the study in 26 tumor and 20 PIN areas. The remaining cases were excluded because of insufficient tissue or poor preservation. Cytogenetic alterations (aneuploidy) were found in 16 of the 26 (62%) tumors studied. The most frequent chromosome alteration was trisomy 7, detected in 12 (75%) aneuploid tumors, followed by monosomy 8 present in 5 (31%) aneuploid tumors. Trisomy 7 was also the most frequent isolated chromosome alteration since it was detected in 7 (44%) tumors. Thirteen of 20 (65%) PIN cases were aneuploid when studied by FISH. Trisomy 7, trisomy 8, and monosomy 8 were the most common cytogenetic alterations in the 20 PIN areas studied, being observed in nine (45%), six (30%), and four (20%) cases, respectively. FISH analysis showed a high correlation (75% cases) in ploidy and pattern of cytogenetic alterations between high-grade PIN areas and the paired prostate cancer focus in the same specimen.

CONCLUSIONS

The above results show a cytogenetic link between high-grade PIN and prostate cancer, suggesting that the former could be an early form of prostate cancer.

Effect of magnesium deficiency on enterocyte Ca, Fe, Cu, Zn, Mn and Se content

In previous studies based on indirect procedures, we reported that Mg deficit increased the bioavailability of a number of elements such as calcium, zinc, iron, copper, manganese and decreased selenium absorption. The present study was designed to verify these findings by direct methods. We investigated the effect of dietary magnesium deficiency on enterocyte Ca, Fe, Zn, Cu, Mn and Se concentrations. Male Wistar rats were fed a Mg-deficient diet (129 mg Mg/kg food) for 70 days. Whole enterocytes from the upper jejunum were isolated and Ca, Fe, Zn, Cu, Mn and Se were determined. The results were compared with findings in a control group that was pair-fed with an identical diet except that it covered this species's nutritional requirements for Mg (480 mg Mg/kg food). The Mg-deficient diet significantly increased enterocyte content of Ca, Fe, Zn, Cu and Mn; however, we found no significant changes in the Se content of these cells. These data support the results obtained by indirect methods.

Numeric alterations in chromosomes 7 and 8 detected by fluorescent in situ hybridization correlate with high-grade localized prostate cancer

OBJECTIVE

To compare the ability of flow cytometry (FCM) and fluorescent in situ hybridization (FISH), using a small set of 4 enumeration chromosome probes to detect aneuploidy in prostate tumors, and to correlate it with histological grade and pathological stage.

METHODS

Among 28 suitable cases, 21 could be analyzed by FISH and FCM techniques. DNA centromeric probes were used in FISH analysis to enumerate chromosomes 7, 8, 10 and 12.

RESULTS

(a) Of the 21 cases studied by FISH, 5 were diploid, 14 aneuploid and 2 were tetraploid. When studied by FCM, these tumors were: 14 diploid, 6 aneuploid, and 1 tetraploid. FISH proved to have a higher ability for detecting DNA aneuploidy than FCM while been equally specific, since all tumors aneuploid by FCM were also found to be aneuploid by FISH. (b) Of the 14 aneuploid tumors, 12 were of high histological grade, while only 2 of the 7 nonaneuploid were of high grade. A statistically significant association was observed between high histological grade and FISH aneuploidy (p = 0.033). (c) All the aneuploid tumors showed chromosome 7 and/or 8 aneusomy. Trisomy 7 and monosomy 8 were the most frequent alterations present in 56 and 42% of the aneuploid tumors, respectively.

CONCLUSION

FISH analysis of chromosome 7 and 8 alterations proved to be more sensitive than FCM in the detection of aneuploid prostate tumors. This aneuploidy was significantly associated with a poor pathological prognosis.

p53 expression predicts progression and poor survival in T1 bladder tumours

OBJECTIVES

Histological grade (G) is the only parameter proved to have prognostic value for progression in T1 transitional cell carcinoma (TCC) of the bladder, although it is considered inaccurate to make clinical decisions on individuals. The aim of the present study was to evaluate the prognostic relevance of p53 expression in T1 TCC of the bladder.

METHODS

Clinical records of 207 patients with T1 TCC of the bladder were reviewed for clinical parameters reported to influence the evolution of superficial bladder cancer. Among these 207 patients, 40 developed muscle-invasive disease (20 G2 and 20 G3). A retrospective case-control study was then carried out comparing the latter 40 tumours with 40 control tumours matched by grade, sex, age, number and size of the tumours, chemical exposure and presence of carcinoma in situ. p53 immunostaining with monoclonal antibody was performed in these two groups.

RESULTS

Histological grade was the only clinical parameter that influenced evolution. p53 expression correlated with tumour progression, since it was observed in 21 out of 24 p53-positive tumours and in only 20 of 56 p53-negative tumours (p<0.0001), showing a specificity of 93. 5% and a sensitivity of 53%. p53 expression correlated as well with patient survival, being 39% in patients with p53-positive tumours and 80% in patients with p53-negative tumours at 60 months (p<0. 0001).

CONCLUSIONS

p53 protein expression has prognostic value for survival and progression in T1 bladder tumours and can be used for early detection of poor-prognosis T1 bladder tumours.

Changes in intramitochondrial and cytosolic pH: early events that modulate caspase activation during apoptosis

Mitochondria trigger apoptosis by releasing caspase activators, including cytochrome c (cytC). Here we show, using a pH-sensitive green fluorescent protein (GFP), that mitochondria-dependent apoptotic stimuli (such as Bax, staurosporine and ultraviolet irradiation) induce rapid, Bcl-2-inhibitable mitochondrial alkalinization and cytosol acidification, followed by cytC release, caspase activation and mitochondrial swelling and depolarization. These events are not induced by mitochondria-independent apoptotic stimuli, such as Fas. Activation of cytosolic caspases by cytC in vitro is minimal at neutral pH, but maximal at acidic pH, indicating that mitochondria-induced acidification of the cytosol may be important for caspase activation; this finding is supported by results obtained from cells using protonophores. Cytosol acidification and cytC release are suppressed by oligomycin, a FoF1-ATPase/H +-pump inhibitor, but not by caspase inhibitors. Ectopic expression of Bax in wild-type, but not FoF1/H+-pump-deficient, yeast cells similarly results in mitochondrial matrix alkalinization, cytosol acidification and cell death. These findings indicate that mitochondria-mediated alteration of intracellular pH may be an early event that regulates caspase activation in the mitochondrial pathway for apoptosis.

Cellular regulation of cytosolic group IV phospholipase A2 by phosphatidylinositol bisphosphate levels

Cytosolic group IV phospholipase A2 (cPLA2) is a ubiquitously expressed enzyme with key roles in intracellular signaling. The current paradigm for activation of cPLA2 by stimuli proposes that both an increase in intracellular calcium and mitogen-activated protein kinase-mediated phosphorylation occur together to fully activate the enzyme. Calcium is currently thought to be needed for translocation of the cPLA2 to the membrane via a C2 domain, whereas the role of cPLA2 phosphorylation is less clearly defined. Herein, we report that brief exposure of P388D1 macrophages to UV radiation results in a rapid, cPLA2-mediated arachidonic acid mobilization, without increases in intracellular calcium. Thus, increased Ca2+ availability is a dispensable signal for cPLA2 activation, which suggests the existence of alternative mechanisms for the enzyme to efficiently interact with membranes. Our previous in vitro data suggested the importance of phosphatidylinositol 4,5-bisphosphate (PtdInsP2) in the association of cPLA2 to model membranes and hence in the regulation of cPLA2 activity. Experiments described herein show that PtdInsP2 also serves a similar role in vivo. Moreover, inhibition of PtdInsP2 formation during activation conditions leads to inhibition of the cPLA2-mediated arachidonic acid mobilization. These results suggest that cellular PtdInsP2 levels are involved in the regulation of group IV cPLA2 activation.

Ligand-dependent interactions of coactivators steroid receptor coactivator-1 and peroxisome proliferator-activated receptor binding protein with nuclear hormone receptors can be imaged in live cells and are required for transcription

Members of the nuclear receptor superfamily are thought to activate transcription by recruitment of one or more recently identified coactivator complexes. Here we demonstrate that both peroxisome proliferator-activated receptor binding protein (PBP) and steroid receptor coactivator-1 (SRC-1) are required for ligand-dependent transcription of transiently transfected and chromosomally integrated reporter genes by the estrogen receptor (ER) and retinoic acid receptor (RAR). To examine ligand-dependent interactions between nuclear receptors and specific coactivators in living cells, these proteins were tagged with cyan (CFP) and yellow (YFP) mutants of the green fluorescent protein. Fluorescence resonance energy transfer (FRET) from the CFP to the YFP indicated interaction between the receptor and coactivator. CFP fusions to RAR or its ligand-binding domain exhibited rapid ligand-dependent FRET to YFP-tagged nuclear receptor interaction domains of the coactivators SRC-1 and PBP. The ER-ligand-binding domain, unlike RAR, also exhibited some basal interaction with coactivators in unstimulated cells that was abolished by the receptor antagonists tamoxifen or ICI182,780. Inhibition of FRET by tamoxifen but not ICI182,780 could be reversed by estradiol, whereas estradiol-enhanced FRET could not be inhibited by either antagonist, indicating that ligand effects can show varying degrees of hysteresis. These findings suggest that ligand-dependent transcriptional activities of the RAR and ER require concurrent or sequential recruitment of SRC-1 and PBP-containing coactivator complexes.

Organelle pH studies using targeted avidin and fluorescein-biotin

BACKGROUND

Mammalian organelles of the secretory pathway are of differing pH. The pH values form a decreasing gradient: the endoplasmic reticulum (ER) is nearly neutral, the Golgi is mildly acidic and the secretory granules are more acidic still ( approximately pH 5). The mechanisms that regulate pH in these organelles are still unknown.

RESULTS

Using a novel method, we tested whether differences in H(+) 'leak' and/or counterion conductances contributed to the pH difference between two secretory pathway organelles. A pH-sensitive, membrane-permeable fluorescein-biotin was targeted to endoplasmic-reticulum- and Golgi-localized avidin-chimera proteins in HeLa cells. In live, intact cells, ER pH (pH(ER)) was 7.2 +/- 0.2 and Golgi pH (pH(G)) was 6.4 +/- 0.3 and was dissipated by bafilomycin. Buffer capacities of the cytosol, ER and Golgi were all similar (6-10 mM/pH). ER membranes had an apparent H(+) permeability three times greater than that of Golgi membranes. Removal of either K(+) or Cl(-) did not affect ER and Golgi H(+) leak rates, or steady-state pH(G) and pH(ER).

CONCLUSIONS

The Golgi is more acidic than the ER because it has an active H(+) pump and fewer or smaller H(+) leaks. Neither buffer capacity nor counterion permeabilities were key determinants of pH(G), pH(ER) or ER/Golgi H(+) leak rates.

Influence of magnesium deficiency on the bioavailability and tissue distribution of iron in the rat

We investigated the effect of dietary magnesium (Mg) deficiency on the nutritive utilization and tissue distribution of iron (Fe). Wistar rats were fed an Mg-deficient diet (56 mg/kg) for 70 days. Absorbed Fe, Fe balance, number of the erythrocytes [red blood cells (RBC)] and leukocytes white blood cells (WBC)], hemoglobin (Hb), and Fe content were determined in samples of plasma, whole blood, skeletal muscle, heart, kidney, liver, spleen, femoral bone, and sternum obtained on experimental days 21, 35, and 70. The Mg-deficient diet significantly increased Fe absorption and Fe balance from week 5 until the end of the experimental period. This effect was accompanied by a significant decrease in the concentration of RBC and Hb from day 35, which caused the decrease in whole blood Fe seen on day 70. However, WBC were significantly increased from day 21 until the end of the experimental period. Mg deficiency significantly increased plasma and liver Fe at all three time points investigated. Spleen, heart, and kidney Fe were significantly increased only at the end of the study. However, on day 70, Fe concentration in the sternum had decreased significantly. No changes were found in skeletal muscle or femur Fe content. Mg deficiency led to increased intestinal absorption of Fe and decreased RBC counts, possibly as a result of increased fragility of the erythrocytes. Intestinal interactions between Fe and Mg, together with activation of erythropoiesis as a result of hemolysis, favored intestinal absorption of Fe. This situation gave rise to an increase in plasma Fe levels, which in turn favored Fe uptake and storage by different organs, especially the liver and spleen. However, despite the increased Fe content seen in the tissues of rats fed the Mg-deficient diet, these animals were unable to compensate for the hemolysis caused by this nutritional deficiency.

Magnesium-manganese interactions caused by magnesium deficiency in rats

OBJECTIVE

We investigated the effect of dietary magnesium (Mg) deficiency on the nutritive utilization and tissue distribution of manganese (Mn).

METHODS

Wistar rats were fed a Mg-deficient diet (56 mg/kg) for 70 day. Absorbed Mn, Mn balance and Mn content in plasma, whole blood, skeletal muscle, heart, kidney, liver, femoral bone and sternum were determined after 21, 35 and 70 days.

RESULTS

The Mg-deficient diet significantly increased Mn apparent absorption and Mn balance from week five until the end of the experimental period. This effect was accompanied by a significant increase in the concentration of Mn in heart at all three time points. Whole blood, skeletal muscle and kidney Mn were significantly increased from day 35, and femur Mn content was increased only at the end of the study (day 70). However, Mn concentration in the sternum decreased significantly from day 35. No changes were found in liver Mn content.

CONCLUSION

Mg deficiency increased Mn absorbed, and this favored the deposition of Mn in all tissues studied except the liver and trabecular bone. The lack of response by the liver to increased Mn absorption may have led to the redistribution of this ion to other tissues.

Cameleon calcium indicator reports cytoplasmic calcium dynamics in Arabidopsis guard cells

Cytoplasmic free calcium ([Ca2+]cyt) acts as a stimulus-induced second messenger in plant cells and multiple signal transduction pathways regulate [Ca2+]cyt in stomatal guard cells. Measuring [Ca2+]cyt in guard cells has previously required loading of calcium-sensitive dyes using invasive and technically difficult micro-injection techniques. To circumvent these problems, we have constitutively expressed the pH-independent, green fluorescent protein-based calcium indicator yellow cameleon 2.1 in Arabidopsis thaliana (Miyawaki et al. 1999; Proc. Natl. Acad. Sci. USA 96, 2135-2140). This yellow cameleon calcium indicator was expressed in guard cells and accumulated predominantly in the cytoplasm. Fluorescence ratio imaging of yellow cameleon 2.1 allowed time-dependent measurements of [Ca2+]cyt in Arabidopsis guard cells. Application of extracellular calcium or the hormone abscisic acid (ABA) induced repetitive [Ca2+]cyt transients in guard cells. [Ca2+]cyt changes could be semi-quantitatively determined following correction of the calibration procedure for chloroplast autofluorescence. Extracellular calcium induced repetitive [Ca2+]cyt transients with peak values of up to approximately 1.5 microM, whereas ABA-induced [Ca2+]cyt transients had peak values up to approximately 0.6 microM. These values are similar to stimulus-induced [Ca2+]cyt changes previously reported in plant cells using ratiometric dyes or aequorin. In some guard cells perfused with low extracellular KCl concentrations, spontaneous calcium transients were observed. As yellow cameleon 2.1 was expressed in all guard cells, [Ca2+]cyt was measured independently in the two guard cells of single stomates for the first time. ABA-induced, calcium-induced or spontaneous [Ca2+]cyt increases were not necessarily synchronized in the two guard cells. Overall, these data demonstrate that that GFP-based cameleon calcium indicators are suitable to measure [Ca2+]cyt changes in guard cells and enable the pattern of [Ca2+]cyt dynamics to be measured with a high level of reproducibility in Arabidopsis cells. This technical advance in combination with cell biological and molecular genetic approaches will become an invaluable tool in the dissection of plant cell signal transduction pathways.

Ability of a cocoa product to correct chronic Mg deficiency in rats

Epidemiological studies have reported that Western diets are often deficient in Mg. We investigated the ability of a cocoa-derived product, used in some European countries as a dietary complement added to milk, to aid recovery from chronic Mg deficiency in rats. The animals were divided into three groups, each of which received a different amount of dietary Mg. Rats in the Mg-deficient (D) group received an Mg-deficient diet (0.225 g Mg/kg food) during 8 weeks. In the cocoa-supplement group (D + CC), the rats consumed the Mg-deficient diet for 5 weeks, and were then switched for 3 further weeks to the same diet supplemented with 3% (wt/wt) cocoa product, so that the Mg content of the diet was 0.27 g/kg food. Rats in the control group (C) were given the same diet as in group D, except that the amount of Mg was 0.56 g Mg/kg food. We measured the concentration of Mg, Ca and P from ten rats in plasma, whole blood, skeletal muscle, heart, kidney and femur in rats that were fed the diets for 35, 42, 49 or 56 days. In animal fed the cocoa-supplemented diet (D + CC) significant improvements were found between days 35 and 56 in the alterations in Mg, Ca and P caused by Mg deficiency in all tissues studied. On day 56, kidney and bone concentrations of Mg and Ca had returned to normal. Our findings show that the habitual use of the cocoa product as a dietary supplement favors correction of the negative effects of long-term feeding with a diet moderately deficient in Mg.

[Evaluation of the body composition by anthropometry and bioelectric impedance in a group of elderly patients recovering from cerebrovascular accidents]

Body composition was assessed by bioelectrical impedance and anthropometry in 25 subjects, 13 men and 12 women aged 68 +/- 9 with approximately 1 year of recovering from stroke. Most of them with a high independence in their diary activities. The main purpose of this study is to know the body composition of elderly patients with this pathology and how affects the two compartments, fat mass and fat free mass when they are measured by two different techniques anthropometry and BIA. Body Mass Index was higher in women than in men and correlation coefficient (r = 0.6) with body fat per cent was similar with both methods: BIA and anthropometry. The body fat per cent values obtained by BIA showed the same trend to be lower for men than for women and in general were higher than the anthropometric values; the high correlation between the body fat per cent by anthropometry and by BIA support this tendency (r = 0.748, p < 0.01). The comparative studies of ours results in elderly subjects recovered from stroke and the literature data in healthy elderly subjects suggests that this pathology do not lean to important changes in body composition. However, further research is necessary to confirm these results.

Measurement of cytosolic, mitochondrial, and Golgi pH in single living cells with green fluorescent proteins

Many cellular events depend on a tightly compartmentalized distribution of H+ ions across membrane-bound organelles. However, measurements of organelle pH in living cells have been scarce. Several mutants of the Aequorea victoria green fluorescent protein (GFP) displayed a pH-dependent absorbance and fluorescent emission, with apparent pKa values ranging from 6.15 (mutations F64L/S65T/H231L) and 6.4 (K26R/F64L/S65T/Y66W/N146I/M153T/ V163A/N164H/H231L) to a remarkable 7.1 (S65G/S72A/T203Y/H231L). We have targeted these GFPs to the cytosol plus nucleus, the medial/trans-Golgi by fusion with galactosyltransferase, and the mitochondrial matrix by using the targeting signal from subunit IV of cytochrome c oxidase. Cells in culture transfected with these cDNAs displayed the expected subcellular localization by light and electron microscopy and reported local pH that was calibrated in situ with ionophores. We monitored cytosolic and nuclear pH of HeLa cells, and mitochondrial matrix pH in HeLa cells and in rat neonatal cardiomyocytes. The pH of the medial/trans-Golgi was measured at steady-state (calibrated to be 6.58 in HeLa cells) and after various manipulations. These demonstrated that the Golgi membrane in intact cells is relatively permeable to H+, and that Cl- serves as a counter-ion for H+ transport and likely helps to maintain electroneutrality. The amenability to engineer GFPs to specific subcellular locations or tissue targets using gene fusion and transfer techniques should allow us to examine pH at sites previously inaccessible.