Organizational design: the case of SARS-CoV-2 vaccination in a healthcare centre.

Background: Only recently Anti-Covid-19 strategies have been applied through specific vaccines, that are a decisive support to modify the evolution of the disease and to reduce the contagion curve. Along vaccination campaigns, the necessity to guarantee rapidity and effectiveness is a critical challenge for all health organizations; their operative capability is applied to carry out govern plans, to ensure safety of the procedures, to adopt good clinical practices, to help with adhesion to vaccine administration and to monitor adverse effects. Study design: The "Centro Clinico Morgagni" is a private accredited diagnosis and treatment Centre with high specialty departments and several hospital beds. The challenge for its administration was to complete the vaccination of all the staff, so a COVID19 crisis unit was established to assure the control of all activities in the center throughout the pandemic. The goal was to complete the vaccination plan following the guidelines with no risks or harm. Methods: An original organizational model, based on different planning methodologies was developed, its task was to define a standard procedure and to give operational instructions based on ISO 9001 for monitoring the entire vaccination process. Also, the model had to define every responsibility role and it had to follow Joint Commission International's methodologies as far as error barriers, drug conservation risks, drug transport and drug administration were concerned.Furthermore, in agreement with the HACCP system, critical control points were highlighted during all the process. The results have been processed in the form of quick references and illustrative panels based on relevant process aspects, which were given to the staff involved in the operations as reference tools for prompt consultation. Results: The vaccination operations at the Centro Clinico Morgagni took place quickly in only four days: 800 staff units were vaccinated - first and second doses with Covid19 mRNA BNT162b2 (Cominraty) - in three different vaccination centers without highlighting significant events that did not comply with the guidelines, nor deviations from the established goals. More precisely, starting from 277 bottles corresponding to six doses each, only 0.2% was wasted, while ADR monitoring reported a prevalence of adverse effects in females (78%) compared to males (22%). Adhesion for vaccination of qualified personnel, thanks to the activities of the Medical College set up for this purpose, reached 100% of the candidate staff through repeated personalized interviews with only one opposition, compared to the 30 communicated at the beginning. Conclusions: It was necessary to ensure the efficiency of the entire process and the model was tested positively. This model can also provide a security control of all the vaccinated personnel; its schematization allows an easy application and flexibility, thus making it an organizational tool that could be reproduced and transferred to other contexts.

[Hematological and iron parameters to predict mortality in ESRD]. / I parametri ematologici e marziali come predittivi di mortalità in emodialisi.

The prognostic value of hematological parameters other than hemoglobin (Hb) has been seldom investigated in hemodialysis (HD) patients. We used the predialytic assessment of blood ferritin, blood transferrin, transferrin saturation, blood iron, total iron binding capacity (TIBC), Hb, reticulocyte count, IRF, mean corpuscular volume (MCV), RDW, CHR, in our HD patients, as well as the weekly iron and erythropoietin (EPO) supplementation, to evaluate the relationship with death in the subsequent 12-month period. Data were divided into two groups (group M for dead patients and group V for patients remaining alive after 12 months) and mean +/- SD with significant differences (Student's t-test) were calculated. The following results were obtained: blood transferrin: M (n=21) 1.78 +/- 0.57, V (n=96) 1.72 +/- 0.36 g/L (p=ns); blood iron: M (n=22) 8.66 +/- 5.07, V (n=97) 10.50 +/- 4.57 mmol/L (p=ns); TIBC: M (n=21) 42.69 +/- 13.63, V (n=98) 40.36 +/- 10.33 mmol of iron/L (p=ns); transferrin saturation: M (n=21) 22.10 +/- 13.07, V (n=96) 25.81 +/- 11.79% (p=ns); blood Hb: M (n=22) 107.55 +/-19.70, V (n=98) 111.02 +/- 14.68 g/L (p=ns); MCV: M (n=22) 94.58 +/- 7.35, V (n=98) 93.27 +/- 8.16 fL (p=ns); RDW: M (n=22) 16.60 +/- 1.51, V (n=98) 15.83 +/- 1.39 (p<0.022); soluble transferrin receptors: M (n=18) 1.85 +/- 0.90, V (n=90) 1.89 +/- 0.75 mg/L (p=ns); reticulocyte count: M (n=22) 91.38 +/- 34.69, V (n=98) 87.27 +/- 29.56 *10 9 /L (p=ns); CHR: M (n=22) 31.36 +/- 2.92, V (n=98) 31.46 +/- 3.08 pg (p=ns); IRF: M (n=22) 24.81 +/- 7.55, V (n=98) 23.65 +/- 8.64 (p=ns); intravenous Fe+++ weekly supplementation: M (n=22) 45.45 +/- 26.81, V (n=98) 37.31 +/- 32.25 mg/week (p=ns); a-EPO weekly supple-mentation: M (n=22) 9090.91 +/- 7824.92, V (n=97) 9030.93 +/- 8292.13 UI/week (p=ns). Since it was not feasible to compare an individual event such as death with the spectra of laboratory data or the administered drug amount, the values of each series were in descending order and the number of M patients (approximately 20% of the total) falling into the upper or lower 20% of values was calculated. In front to the expected amount of 4.4 M for each 20%, two M patients fell into the upper 20% and six patients into the lower 20% of blood ferritin values, and, correspondingly, two vs. nine patients for blood iron, four vs. seven patients for transferrin saturation, three vs. seven patients for blood Hb, eight vs. two patients for RDW and six vs. two patients for iron supplementation. Therefore, our patients with a negative prognosis showed an increase in RDW and an iron availability or metabolism disorder.

Atherosclerotic risk factors and renal function in the elderly: the role of hyperfibrinogenaemia and smoking. Results from the Italian Longitudinal Study on Ageing (ILSA).

BACKGROUND: We examined associations between cardiovascular diseases and risk factors with pathological levels of and significant changes in serum creatinine (SCr) in a large prevalence phase and longitudinal phase community-based sample of an elderly Italian population (ILSA Study) showing no clinical evidence of renal impairment. METHODS: The prevalence phase was performed on 2981 subjects, aged 65-84 years, who were negative for renal diseases, had available SCr values and had complete clinical information on their cardiovascular risk factors. Of these, 371 were considered 'healthy' since they were not affected by cardiovascular diseases or diabetes, whereas 2610 tested positive for cardiovascular diseases and were considered 'diseased'. The sex-specific 95th percentiles for SCr (cut-off points) were calculated in the healthy reference sample to define the upper limit for normal SCr values. The distribution and prevalence of diseased subjects having values over the cut-off point values were then estimated. Associations between values over the cut-off point levels and pathological or clinical conditions were analysed from the diseased sample. The longitudinal phase was carried out on 1906 subjects who had SCr values and sufficient clinical information for our investigation. The incidence of an increase of >26.5 micromol/l of SCr was evaluated in the longitudinal cohort. RESULTS: In healthy subjects, the 95th SCr percentiles (cut-off points) were 123.8 micromol/l in men and 97.2 micromol/l in women. In diseased subjects, the prevalence of SCr values over the cut-off point was 4.6% in men and 9.3% in women. In logistic regression analysis, independent variables that correlated with over the cut-off point SCr values were: age >75 years [odds ratio (OR) = 2.2; 95% confidence interval (CI) = 1.5-3.4], atherosclerosis of the lower limbs (OR = 2.0; 95% CI = 1.2-3.3), cerebrovascular disease (OR = 1.9; 95% CI = 1.2-3.3), angiotensin-converting enzyme (ACE) inhibitor medication (OR = 1.8; 95% CI = 1.2-2.8), fibrinogen values >3.5 g/l (OR = 1.2; 95% CI = 1.2-2.7) and diuretic treatment (OR = 1.6; 95% CI = 1.1-2.4). After a mean 3.6 years follow-up, multiple logistic regression analysis showed that risk factors for pathological loss of renal function (rise of SCr >26.5 micromol/l) were: current smokers >20 cigarettes/day (OR = 2.3; 95% CI = 1.0-5.3), fibrinogen values >3.5 g/l (OR = 2.2; 95% CI = 1.6-3.3), diabetes (OR = 1.8; 95% CI = 1.1-2.8), age >75 years (OR = 1.7; 95% CI = 1.2-2.4) and isolated systolic hypertension (OR = 1.6; 95% CI = 1.0-2.6). The loss of renal function examined during the longitudinal phase appeared to be independent of baseline SCr levels. CONCLUSION: The present prevalence and longitudinal studies show that age-associated decline in renal function in elderly subjects is associated with co-existing cardiovascular diseases and risk factors. These observations should be incorporated into clinical practice since some of the factors detrimental to kidney function, such as smoking, altered fibrinogen levels and elevated systolic blood pressure, can be prevented and/or modified when appropriate measures are taken.

Urinary excretion of vasoactive substances in chronic renal failure.

To investigate the pathophysiological role of vasoactive substances in the progression of chronic renal disease, we measured the 24-hour urinary excretion of prostaglandin 6-keto F1alpha, thromboxane B2, NOx, cGMP and ET-1 in 26 patients with chronic renal failure under conservative treatment and in 40 control subjects. Urinary 6-keto PgF1alpha, TxB2 and cyclic GMP were evaluated by RIA, and ET-1 was assayed by EIA. NOx were evaluated using a colorimetric assay as nitrate/nitrite. Urinary excretion of prostaglandin 6-keto F1alpha averaged 18.1 +/- 20.9 ng/g Ucreat in patients vs. 240.9 +/- 257.3 in controls (p < 0.0001), thromboxane B2 422 +/- 374 ng/g Ucreat in patients vs. 967 +/- 589 in controls (p < 2x 10(-5)), NOx 7.07 +/- 5.54 mg/g Ucreat in patients vs. 9.79 +/- 3.77 in controls (p < 0.01), cGMP 310 +/- 200 pg/g Ucreat in patients vs. 488 +/- 241 in controls (p < 0.001). In contrast, ET-1 urinary excretion was almost doubled in patients (13.45 +/- 5.84 ng/g of Ucreat) in comparison with controls (6.84 +/- 2.81 p < 1x10(-5)). While in control subjects significant correlations between urinary excretions of prostaglandin 6-keto F1alpha and thromboxane B2 (r = 0.69, p < 0.001) or NOx and ET-1 (r = 0.54, p < 0.001) were present, in patients only the relationship between urinary excretions of prostaglandin 6-keto F1alpha and thromboxane B2 (r = 0.53, p < 0.01) was retained. Our data suggest that in the normal kidney a balance between prostaglandin I2 and thromboxane A2, or nitric oxide and endothelin-1 is present, which contributes to hemodynamic regulation and protects this organ from ischemic damage. This balance is abolished in CRF, where a large increment of vasopressor agent endothelin is present, which, joined to a prevalent decrease of prostaglandin I2 synthesis, could contribute to the ischemic and fibrogenetic damage of the kidney, leading to progression of renal disease.

Cyclosporin-induced endothelial dysfunction and hypertension: are nitric oxide system abnormality and oxidative stress involved?

Hypertension is a major side effect of cyclosporin (CsA). While the mechanism(s) responsible are unclear, CsA-induced endothelial dysfunction and CsA-induced hypertension have been attributed to the CsA effect on the endothelial-derived factors controlling vasomotor tone. Endothelial nitric oxide (NO) is crucial in the maintenance of a state of basal vasodilation, and recent studies have suggested an NO-mediated counterregulatory mechanism protective from CsA-induced vasoconstriction. Our study evaluates endothelial nitric oxide synthase (ecNOS) gene status (PCR analysis) and plasma levels of NO metabolites (ELISA) in kidney and heart transplant patients under chronic CsA treatment with CsA-induced hypertension. Since CsA increases superoxide production, which metabolises NO, plasma hydroperoxides from cholesterol esters and from triglycerides and peroxynitrite were also evaluated (HPLC) as an index of the presence of superoxides and of "oxidative stress". Quantification of monocyte ecNOS mRNA and NO metabolites plasma levels from patients and controls (C) demonstrated NO system upregulation in patients notwithstanding the hypertension. The mean ecNOS to beta-actin ratio was 1.80 +/- 0.85 in patients vs 0.40 +/- 0.09 in C (P < 0.04). NO metabolites were 34.03 +/- 14.32 microM in patients vs 11.53 +/- 5.64 microM in C (P < 0.001). Hydroperoxides from cholesterol esters and from triglycerides were also increased in patients, 3.4 +/- 1.4 vs 1.3 +/- 0.6 integrated area units (i. a. u.), P < 0.007 and 10.6 +/- 6.4 vs 1.3 +/- 0.8 i. a. u., P < 0.008, respectively, as well as the peroxynitrite plasma level, 0.32 +/- 0.11 microM/l vs undetectable in C. This study confirms a CsA-induced NO system upregulation in transplanted patients. However, the NO-mediated counterregulatory system to CsA-induced vasoconstriction, present in normals, could be canceled in patients by CsA-induced superoxide (O2-) and free radical production which, by increasing NO metabolism, could contribute to CsA-induced vasoconstriction and hypertension and predispose to atherosclerosis.

Idiopathic hypercalciuria: O2(-)NO relationship and altered bone metabolism.

The pathogenesis of idiopathic hypercalciuria (IH) has not been elucidated yet, but a correlation between IH and altered bone metabolism has been proposed. Since nitric oxide (NO) regulates osteoclasts' bone resorption, a possible role for NO can be suggested. In this study we evaluated iNOS gene expression by reverse transcription of mRNA from monocytes, followed by polymerase chain reaction in patients with IH subdivided into fasting (FH) and absorptive (AH) hypercalciuria. Since superoxide (O2-), which metabolizes NO, is overproduced by osteoclasts during bone resorption, peroxynitrite plasma level was evaluated as index of O2-. Vertebral BMD in IH as a whole group was lower vs controls (C) (Z score=-1.78+/-0.2 vs 0.51+/-0.25, p<0.001), but only FH patients showed a reduced bone density (2.13+/-0.18 vs 0.51+/-0.25, p<0.0001). PTH and calcitriol were not different. FH showed an increase in b-ALP vs AH and C (41.1+/-2.6 vs 30.1+/-3.9 vs 26.6+/-3.6 U/l p<0.02), and higher uHP, either on NCD (17.7+/-1.6 vs 11.4+/-1.3 mg/g uCr, p<0.04) or after LCD (26.7+/-2.5 vs 16.7+/-1.9, p<0.01). Cells from FH patients, but not from both AH patients and C, expressed iNOS. Peroxynitrite plasma level was elevated in FH (0.30+/-0.07) pmol/l while not detectable in AH and C. This study confirms an altered bone metabolism only in FH which shows an abnormal NO system. The increased iNOS gene expression in FH, in fact, points toward an altered NO system's activity downstream the generation of NO. A possible interaction of NO with O2-, which breaks down NO, and the role of this interaction in the pathophysiology of IH is discussed.

Oxidative stress and nitric oxide system in post-transplant hypertension.

BACKGROUND: CsA-induced endothelial dysfunction and CsA-induced hypertension have been attributed to CsA effects on the endothelial-derived factors controlling vasomotor tone, but the mechanisms responsible are unclear. Endothelial nitric oxide (NO) is known to maintain a state of basal vasodilation and recently a NO mediated counterregulatory mechanism protective from CsA-induced vasoconstriction has been suggested. PATIENTS AND METHODS: Our study evaluates ecNOS gene status and NO metabolites in kidney transplanted patients under chronic CsA treatment with CsA-induced hypertension. Since CsA increases superoxide production, which metabolizes NO, plasma hydroperoxides and peroxynitrite were also evaluated as index of the presence of "oxidative stress". RESULTS: Quantification of monocyte ecNOS mRNA and NO metabolites plasma level from patients and control subjects (C) demonstrated NO system up regulation in patients notwithstanding hypertension. The mean ecNOS to beta-actin ratio was 2.00 +/- 0.87 vs 0.29 +/- 0.08 in C, p < 0.04. NO metabolite plasma level was 30.03 +/- 9.62 mM vs 9.37 +/- 3.86, p < 0.001. Hydroperoxides were also increased in patients: 3.6 +/- 1.6 i.a.u. vs 1.4 +/- 0.8, p < 0.007 (from cholesterol esters) and 10.8 +/- 6.6 vs 1.5 +/- 0.9, p < 0.008 (from triglycerides) as well as peroxynitrite plasma level: 0.36+/- 0.14 mM/L vs undetectable in C. CONCLUSIONS: This study confirms a NO system up-regulation in transplanted patients. However, the counterregolatory system to CsA-induced vasoconstriction, could be cancelled by CsA induced superoxide and free radicals production which, increasing NO metabolism could contribute to CsA induced vasoconstriction and hypertension.

Increased endothelial nitric oxide synthase mRNA level in Bartter's and Gitelman's syndrome. Relationship to vascular reactivity.

AIM: Patients with Bartter's syndrome and Gitelman's syndrome have reduced vascular reactivity, normo-hypotension and decreased peripheral resistances in spite of biochemical and hormonal abnormalities typical of hypertension. Since we found that both types of patients have increased urinary NO2-/NO3-, metabolites of NO, that correlated with their increased urinary cGMP, second messenger of NO, we examined the possible role of NO system in the pathophysiology of these syndromes. PATIENTS AND METHODS: We used a molecular biologic approach and studied ecNOS gene expression by PCR-amplification of cDNA obtained by RT-PCR of RNA extracted by patients and healthy controls monocytes. RESULTS: ecNOS is overexpressed in monocytes from patients with Bartter's and Gitelman's syndrome relative to controls: - 0.306 +/- 0.012 Densitometric Units (0.313 +/- 0.006, N = 3 for Bartter's patients; 0.302 +/- 0.009, N = 5 for Gitelman's patients) vs. 0.192 +/- 0.018, p < 0.0001. CONCLUSION: This overexperession presumably accounts for their increased NO production; thus it could be likely that elevated ecNOS and NO levels are a part of pathophysiological process(es) that leads to their characteristic reduced vascular responses. However, the relationship between the alterations in the NO signalling system observed in this study and the mutations in either Na+-K+-2Cl cotransporter or in a K+ channel ROMK or in Cl- channel ClCNKB in Bartter's syndrome and in Na+-Cl- cotranstransporter in Gitelman's syndrome, recently reported as their primary defects remains to be defined.

Reduced susceptibility to oxidation of low-density lipoprotein in patients with overproduction of nitric oxide (Bartter's and Gitelman's syndrome).

BACKGROUND: The oxidation of low-density lipoprotein (LDL) might play an important role in the development of atherosclerosis. OBJECTIVE: To establish whether greater than normal production of nitric oxide (NO) in vivo protects LDL from oxidation. PATIENTS AND METHODS: We studied nine subjects affected by Bartter's and Gitelman's syndrome (both characterized by greater than normal production of NO), and 10 subjects matched for age, sex and lipid levels as controls. LDL particles were isolated from plasma by density gradient ultracentrifugation. Susceptibility of LDL to oxidation was evaluated after incubation with copper sulfate solution, by measuring the formation of conjugated dienes, the thiobarbituric acid-reactive substances, and the volatile peroxidation products of n-3 (propanal) and n-6 (pentanal and hexanal) polyunsaturated fatty acids. Phospholipid fatty acid composition of LDL was determined by gas chromatography. LDL alpha-tocopherol concentrations were measured. RESULTS: Patients with Bartter's and Gitelman's syndrome had LDL particles smaller and/or denser than those of controls [Rf = 0.38 +/- 0.03 versus 0.42 +/- 0.02 (mean +/- SD), P < 0.01], which hence were assumed to be more oxidizable. The phospholipid fatty acid composition of LDL and the alpha-tocopherol concentrations did not significantly differ between patients and controls. The duration of the lag phase, which is the time preceding formation of conjugated dienes, did not differ between groups, but the lag phase times were related to urinary excretion of nitrite/nitrate from patients (r = 0.66, P < 0.05). Moreover, patient LDL had produced less thiobarbituric acid-reactive substances after 5 h (P < 0.04), and less pentanal and hexanal after 5 and 6 h (P < 0.04 and P < 0.02, respectively) than had that of controls. CONCLUSIONS: Greater than normal production of NO in vivo is associated with lower than normal susceptibility of LDL to oxidation in vitro, suggesting that NO plays a protective role in the development of atherosclerosis.

In vivo and in vitro neurotoxic action of plasma ultrafiltrate from uraemic patients.

BACKGROUND: In order to investigate the aetiology of uraemic neuropathy, we evaluated the neurotoxic activity of plasma from uraemic patients. To this end we prepared a concentrate (1:1000) of 2-60 kDa MW compounds from paired filtration dialysis ultrafiltrate and evaluated its activity on peripheral nerve conduction in vivo and in vitro. METHODS: The in vivo neurotoxicity was tested on rat sciatic nerve by intraneural injection of the uraemic concentrate, followed, 1 to 6 days later, by electrophysiological assessment of motor response and maximum conduction velocity. In vitro experiments were performed on isolated frog sciatic nerve in the presence of uraemic concentrate, and the neurotoxicity was evaluated from the rate of the decrease in the amplitude of the evoked maximal action potential. RESULTS: In the in vivo experiments, the sciatic nerves injected with the uraemic concentrate showed a decrease in maximum conduction velocity and a progressive impairment in evoked motor response. In the in vitro experiments uraemic concentrate induced a dose-dependent neurotoxic effect. CONCLUSIONS: Our study demonstrates the presence in plasma of uraemic patients of a compound of 2-60 kDa MW with neurotoxic activity.

Effect of doxazosin in mild to moderate hypertensive patients with insulin-dependent diabetes mellitus.

Diabetic patients often develop hypertension, and the presence of both hypertension and diabetes doubles the risk of death from coronary heart disease (CHD). Moreover, the presence and importance of abnormalities such as high low-density lipoprotein (LDL) cholesterol and triglycerides levels as CHD risk factors in insulin-dependent diabetes mellitus type 1 have been downplayed, while increasing evidence suggests that the management of type 1 patients should include control of dyslipidemia and hyperglycemia and an effective antihypertensive treatment able also to reduce risk factors for coronary artery events. In this study we assessed the antihypertensive and metabolic effects of doxazosin in hypertensive patients with type 1 diabetes. We show that the drug normalizes blood pressure, and while no improvement in glucose control was observed, it reduced total cholesterol and increased HDL cholesterol as well as the HDL to total cholesterol ratio. The changes of the various parameters studied, including the calculated CHD risk score based on the Framingham equation, suggest that doxazosine can reduce the CHD risk for hypertensive type 1 patients.

Constitutive endothelial nitric oxide synthase (ecNOS) gene expression in human monocytes.

This study evaluates using a polymerase chain reaction (PCR)-based molecular biological approach to study the gene expression of the constitutive endothelial isoform of nitric oxide synthase (ecNOS) in human monocytes. When PCR was carried out with specific primers for ecNOS, 302 bp product was amplified, which sequence analysis determined as having 100% identity to the reported human ecNOS isoform gene sequence. The data presented here demonstrate a reliable technique for assessing ecNOS mRNA levels in circulating human monocytes. This then permits use of this easily available cell to monitor ecNOS levels and provides a means to investigate mechanisms involved in controlling NO synthase levels as well as NO synthesis.

Urinary NO2- and NO3- evaluation by an ion chromatography system.

We describe an ion chromatography system using a Dionex AS4A-SC column with carbonate-bicarbonate buffer (1.8-1.7 mM) as eluent for the evaluation of urinary NO2- and NO3-. This chromatographic system gives an accurate measurement of NO2- and NO3- in the urine as an index of NO production in vivo, making also possible to evaluate their relative proportion and providing useful tools to investigate the NO system.

Calciotropic hormones and nephrolithiasis.

In recurrent calcium stone formers interfering factors or changes in receptor sensitivity may alter the interrelationships among calcium-regulating hormones, and hormonal behavior often does not fit with the theoretical assumptions. The vitamin D system appears to have the most important metabolic and clinical effects. Abnormal up-regulation of the synthesis of calcitriol and the consequent parathyroid hormone (PTH) suppression can induce hypercalciuria. Consequently, the hypocalciuric effect of thiazide would be caused by an enhanced response to PTH and by a reduction in 1,25(OH)2-vit D. A negative role of vitamin D on the skeleton has been observed in the presence of a negative calcium balance. Moreover, vitamin D also plays a role in urine oxalate excretion. PTH seems not to be directly stimulated in hypercalciuria and recurrent calcium nephrolithiasis, and patients with hyperparathyroidism and recurrent calcium nephrolithiasis show a similar degree of bone demineralization, irrespective of the presence of absence of the so-called 'primary hyperparathyroidism.' Calcitonin plays a contributory role in the pathogenesis of recurrent calcium nephrolithiasis that seems to be strictly related to dietary calcium intake. A higher sensitivity of thyroid C cells, particularly in absorptive hypercalciuric patients, could be related to the pathogenesis of hypercalciuria and contribute to its persistence.

Evidence of myocardial dysfunction in Bartter's syndrome.

Bartter's syndrome (BS) is characterized by arterial normohypotension despite biochemical and hormonal abnormalities generally associated with hypertension. An abnormal intracellular calcium homeostasis due to a reduced capacity to increase intracellular calcium has been demonstrated by us in BS and proposed as the main pathophysiological factor of the vascular hyporeactivity in BS. The present study was designed to assess whether this altered intracellular calcium homeostasis could also impair contractile recruitment at the myocyte level. Left-ventricular function of patients with BS and normal subjects (C) were studied by quantitative 2-D echocardiography at rest and by postextrasystolic potentiation (PESP), an inotropic stimulus able to recruit the maximal contractile reserve. A group of patients with hypokalemia other than BS (PB) was also included in the study to evaluate the effect of hypokalemia on myocardial contractile recruitment. Baseline left-ventricular end-diastolic volume (EDV) and ejection fraction (EF) did not differ in the 3 groups: EDV: 62 +/- 6 vs. 64 +/- 9 and 60 +/- 12 ml/m2; EF: 64 +/- 9 vs. 67 +/- 8 and 64 +/- 8%. PESP determines an increase of EF in C and PB: 82 +/- 5%, p < 0.01 and 76 +/- 6%, p < 0.01, while in BS it is unchanged: 69 +/- 9% and is reduced in comparison with the increment of myocardial function shown by C and PB (p < 0.01). This study is the first demonstration in BS of a depressed inotropic recruitment causing an exercise-induced left-ventricular dysfunction likely due to an abnormal intracellular calcium homeostasis in the myocytes.

Inhibition of furosemide-sensitive cation transport and activation of sodium-lithium exchange by endogenous circulating factor(s) in Bartter's and Gitelman's syndromes.

BACKGROUND: The nature of the cellular abnormality causing hypokalemia, hypotension, and hypovolemia in Bartter's and Gitelman's syndromes is still being debated. In fact, despite the recent descriptions of an array of nonconservative missense or point mutations in some ion transporters and in K+ channel, the lack of detectable defects in some patients suggests that other abnormalities of cell ion homeostasis may be involved in the pathophysiology of these syndromes. The study of the activity of cell ion transporters in patients with these syndromes using red blood cells (RBC) as a cellular model never investigated the role of plasma factor(s) affecting ion transport. OBJECTIVE: To evaluate the effect of plasma from patients with these syndromes on furosemide-sensitive lithium efflux (FSLE) from lithium (Li+)-loaded RBC of healthy subjects in vitro. METHODS: RBC of healthy controls were loaded with Li+ in the presence of nystatin and FSLE was evaluated in the presence of various concentrations of plasma from controls and patients with the two syndromes. RESULTS: Plasma from controls did not affect FSLE (0.08 +/- 0.02 mmol/l cells per h with 1:4 vol:vol and 0.07 +/- 0.02 mmol/l cells per h with 1:2 vol:vol plasma dilution). In contrast, doubling concentrations of plasma from patients with either syndrome in the efflux solution halved FSLE (from 0.10 +/- 0.0 mmol/l cells per h with 1:4 vol:vol to 0.05 +/- 0.01 mmol/l cells per h with 1:2 vol:vol plasma dilution, P < 0.05). Na+/Li+ exchange was significantly greater for RBC from patients with either syndrome than it was for RBC from controls (0.373 +/- 0.06 versus 0.257 +/- 0.01 mmol/l cells per h, P < 0.01), but the kinetic properties of furosemide-sensitive Na+-K+-2Cl- cotransport were similar. CONCLUSION: These data provide evidence for the hypothesis that plasma factor(s) affect ion transport in patients with these two syndromes. Since FSLE estimates Na+-K+-2Cl- cotransport the data suggest that plasma factor(s) contribute(s) to K+ wasting, hypokalemia, and hypotension by inhibiting cotransport in patients with these syndromes. The increase of Na+/Li+ exchange is most likely a secondary phenomenon associated with the hypermineralocorticoid state.

Increased urinary NO2-/NO3- and cyclic guanosine monophosphate levels in patients with Bartter's syndrome: relationship to vascular reactivity.

Nitric oxide (NO) is a potent endogenous vasodilator and plays a pivotal role in the control of vascular tone by the formation of cyclic guanosine monophosphate (GMP). Patients affected by Bartter's syndrome have lower than normal vascular reactivity with normohypotension and decreased peripheral resistances in spite of biochemical and hormonal abnormalities typical of hypertension, and it is possible that increased production of NO may be involved in maintaining this reduced vascular response and vasodilatation. We have examined this possibility by studying NO2-/NO3- and cyclic GMP urinary excretions to assess NO production in vivo in seven patients affected by Bartter's syndrome compared with seven healthy controls. A group of five patients with hypokalemia other than Bartter syndrome (pseudo-Bartters) was also included in the study to evaluate the effect of hypokalemia on NO production. NO2-/NO3- urinary excretion (0.45 +/- 0.14 v 0.25 +/- 0.04 micromol/micromol urinary creatinine [controls], P < 0.005, v 0.28 +/- 0.05 [pseudo-Bartters], P < 0.01) and cyclic GMP urinary excretion (0.057 +/- 0.028 v 0.022 +/- 0.01 micromol/micromol of urinary creatinine [controls], P < 0.009, v 0.024 +/- 0.004 [pseudo-Bartters], P < 0.02) were increased in patients with Bartter's syndrome in comparison with controls and pseudo-Bartters, and a linear correlation between these two parameters was also present (P < 0.001). We conclude that in Bartter's syndrome the increased NO2-/NO3- and cyclic GMP urinary excretions point to an increased NO synthesis, which could account for the reduced vascular response of the disease, therefore adding its role in determining the vascular hyporeactivity of Bartter's syndrome.