PubMed Health⌕ Search

Biomedical subjects

Y Levo

Publications and source records attributed to Y Levo.

At least 19 recordsLinked to original sources
PubMed2006

Arginine uptake is attenuated through modulation of cationic amino-acid transporter-1, in uremic rats.

Endothelial cell dysfunction (ECD) is a common feature of chronic renal failure (CRF). Defective nitric oxide (NO) generation due to decreased endothelial NO synthase (eNOS) activity is a crucial parameter characterizing ECD. L-arginine is the sole precursor for NO biosynthesis. Among several transporters that mediate L-arginine uptake, cationic amino-acid transporter-1 (CAT-1) acts as the specific arginine transporter for eNOS. Our hypothesis implies that CAT-1 is a major determinant of eNOS activity in CRF. We studied glomerular and aortic arginine uptake, CAT-1, and CAT-2 messenger ribonucleic acid (mRNA) expression, and CAT-1 protein in: (a) rats 6 weeks following 5/6 nephrectomy (CRF), (b) sham-operated animals, and (c) rats with CRF treated orally with either atorvastatin or arginine in drinking water (modalities which have been shown to enhance eNOS activity and improve endothelial function). Both glomerular and aortic arginine transport were significantly decreased in CRF. Treatment with either arginine or atorvastatin abolished the decrease in arginine uptake in CRF rats. Using reverse transcriptase-polymerase chain reaction and Northern blotting, we found a significant increase in glomerular and aortic CAT-1 mRNA expression in CRF. Western blotting revealed that CAT-1 protein was decreased in CRF, but remained intact following arginine and atorvastatin administration. Renal and systemic arginine uptake is attenuated in CRF, through modulation of CAT-1 protein. These findings provide a possible novel mechanism to eNOS inactivation and endothelial dysfunction in uremia.

Animals↗
PubMed2003

The economic burden of antibiotic treatment of penicillin-allergic patients in internal medicine wards of a general tertiary care hospital.

BACKGROUND: Penicillin allergy poses a major problem in the management of infectious diseases. OBJECTIVE: We estimated the costs and usage of antibiotic treatment of 'penicillin-allergic' patients in comparison to non-allergic patients in a tertiary care hospital. MATERIALS AND METHODS: The study was based on the records of 118 randomly chosen in-hospital patients labelled as being 'allergic to penicillin' and who were treated with antibiotics. The antibiotic selection and cost of the patients with alleged penicillin allergy were compared to 118 matched patients without an antibiotic allergy (controls). RESULTS: During in-hospital treatment, the mean antibiotic cost for penicillin-allergic patients was 63% higher than the cost for the controls. In addition, there was a 38% higher cost of the recommended anti-microbial treatment regimen to be followed upon discharge by the former compared to the latter. CONCLUSIONS: Penicillin-allergic patients were more likely to receive broader spectrum antibiotics compared to the non-allergic ones. Since many of the patients who are labelled as being 'allergic to penicillin' are, in fact, not allergic to it, inaccurate reporting of penicillin allergies may have costly economic and epidemiologic repercussions in addition to more toxic effects which can occur when choosing alternative drugs in case of penicillin allergy.

Aged↗
PubMed2001

Low levels of IFN-gamma down-regulate the integrin-dependent adhesion of B cells by activating a pathway that interferes with cytoskeleton rearrangement.

In order to fully mature and participate in the humoral immune response, immature B cells must first migrate into specific areas in the spleen where they differentiate into mature cells. However, before their maturation in the spleen, immature B cells must be excluded from non-splenic secondary lymphoid organs where any antigen encounter would lead to the death of the cells because of the negative selection process. We have recently shown that immature B cells can actively exclude themselves from antigen-enriched sites by down-regulating their integrin-mediated adhesion in a process mediated by interferon-gamma (IFN-gamma). In this study, we followed the pathway by which IFN-gamma regulates the homing of B cells. We show here that the inhibitory signal of IFN-gamma is transmitted through the IFN-gamma receptor whose engagement leads to the activation of PI3K. This PI3K activation subsequently leads to the inhibition of PKCalpha phosphorylation and cytoskeleton rearrangement required for promoting integrin-mediated adhesion and migration of B cells.

Actins↗
PubMed2001

Tetrahydrobiopterin augments arginine transport in rat cardiac myocytes through modulation of CAT-2 mRNA.

Tetrahydrobiopterin (BH4) has been shown to be required for dimerization and acquisition of nitric oxide (NO) generating capacity by nitric oxide synthase (NOS). In the present study we have investigated the hypothesis that BH4 may affect NOS activity through a novel mechanism-namely, modulating arginine transport in rat cardiac myocytes. Cardiac myocytes have been previously shown to express cationic amino acid transport proteins (y+ system) CAT-1 and CAT-2. Increasing extracellular BH4 concentrations up to 0.5 mmol/L augments arginine transport in 1 mmol/L arginine media (no BH4, 558 +/- 42 fmol arginine/microg protein/min; 0.1 mmol/L BH4, 580 +/- 11 fmol arginine/microg protein/min; 0.5 mmol/L BH4, 944 +/- 71* fmol arginine/microg protein/min; 1.0 mmol/L BH4, 983+/-84* fmol arginine/microg protein/min, n = 4; *: P <.05 vs no BH4). Treating the cells with lipopolysaccharide (LPS) (10 microg/mL) significantly augmented arginine transport only in the presence of BH4 (no BH4, 600 +/- 33 fmol arginine/microg protein/min; 0.1 mmol/L BH4, 691 +/- 29*dagger fmol arginine/microg protein/min; 0.5 mmol/L BH4, 1123 +/- 32*dagger fmol arginine/microg protein/min; 1.0 mmol/L BH4, 1296 +/- 42*dagger fmol arginine/microg protein/min, n = 4; *: P <.01 vs no BH4, dagger: P <.05 vs no LPS). The administration of biopterin, sodium nitroprusside (NO donor), 2,4-diamino-6-hydroxy-pyrimidine (inhibitor of BH4 synthesis), and sepiapterin (the precursor of de novo synthesis of BH4) to unstimulated cells had no effect on arginine uptake values. Using reverse trancriptase-polymerase chain reaction, we next studied the steady state levels for CAT-1 and CAT-2 mRNA. Incubation with BH4 significantly increased CAT-2 mRNA expression in a concentration-dependent manner in 0.1, 0.5, and 1 mmol/L BH4, respectively. Northern blotting analysis further confirmed this observation. We also found that in the presence of BH4 in these concentrations, CAT-1 mRNA expression was abolished. We suggest that BH4 augments intracellular arginine availability by modulating CAT-2 mRNA expression and suggest that its presence is required for the LPS effect on trans-membrane arginine traffic.

Amino Acid Transport Systems, Basic↗
PubMed2000

Autocrine secretion of interferon gamma negatively regulates homing of immature B cells.

The mechanism by which immature B cells are sequestered from encountering foreign antigens present in lymph nodes or sites of inflammation, before their final maturation in the spleen, has not been elucidated. We show here that immature B cells fail to home to the lymph nodes. These cells can actively exclude themselves from antigen-enriched sites by downregulating their integrin-mediated adhesion to the extracellular matrix protein, fibronectin. This inhibition is mediated by interferon gamma secretion. Perturbation of interferon gamma activity in vivo leads to the homing of immature B cells to the lymph nodes. This is the first example of autocrine regulation of immune cell migration to sites of foreign antigen presentation.

Animals↗
PubMed2000

[Systemic mastocytosis].

Mastocytosis has a highly variable clinical expression, and systemic mastocytosis is occasionally associated with a myeloproliferative or a myelodysplastic disorder. These patients often present without skin involvement and have a very poor prognosis. We report a 72-year-old man with this condition who had spells of flushing and dyspnea, myelofibrosis, and high serum and urine histamine levels.

Aged↗
PubMed1999

Suppressive activity of bronchial macrophages recovered by induced sputum.

BACKGROUND: The immunomodulatory activity of macrophages was shown to be a crucial mechanism in the pathogenesis of asthma. METHODS: Induced sputum (IS) and methacholine challenge (MC) were carried out in 21 atopic subjects. Suppressive activity (SA) of sputum macrophages (SMO) was investigated on autologous peripheral lymphocytes (APL) proliferation in 12 of these patients and compared to the MC. RESULTS: In 10 of the 21 patients, the FEV1 was >80%; five of these had a nonreactive MC. Eosinophils and metachromatic cells correlated well (r=0.6442; P=0.0029), but not with the MC. The SA of SMO correlated (P=0.0152) with the MC: SMO enhanced APL proliferation in five patients with a positive MC, while SMO showed SA in five with a negative MC. Only two patients with suppressive SMO had a positive MC. Cytokine profiles from five patients showed that two patients with a negative MC had interleukin (IL)-1alpha and beta, IL-6, and transforming growth factor (TGF)-beta transcripts, while two patients with a positive MC transcripted IL-4 and IL-5. One patient with a borderline MC transcripted IL-5, but not IL-4. CONCLUSIONS: These data support the theory that patients with reduced suppressive bronchial macrophages display clinical bronchial hyperreactivity.

Adult↗
PubMed1999

The effect of various hormonal preparations and calcium supplementation on bone mass in early menopause. Is there a predictive value for the initial bone density and body weight?

OBJECTIVES: To compare the effect of various oestrogen and oestrogen/progestin preparations on bone density over a 2-year follow-up period in early postmenopausal women. SETTING: A retrospective study on 315 women followed in a menopause clinic. DESIGN: Antero-posterior lumbar spine bone densitometry was performed at baseline and between 18 and 24 months (mean 22 months) after initiation of hormone therapy. Participants were divided into six groups: women taking conjugated equine oestrogen (CEE) (n = 30); CEE plus sequential monthly medroxyprogesterone acetate (MPA) (n = 52); CEE plus sequential bimonthly MPA (n = 51); oral estradiol plus sequential monthly norethisterone acetate (n = 52); transdermal estradiol plus sequential monthly MPA (n = 30). A control group (n = 100) was composed of nonusers of hormones. RESULTS: Hormone users, as a whole (n = 215), increased their bone mineral density (BMD) by 2.9% (4.8) as compared to the controls who lost 3.5% (3.4; P < 0. 001). There were similar gains in BMD amongst the five study groups. Calcium supplementation was associated with better results in all women: users of hormones and calcium had a gain in BMD of 4.5% (4.8) compared to only 1.5% (4.5) in those on hormones but without calcium (P < 0.001); amongst the controls, women using calcium lost 1.4% (2. 4), whilst nonusers of calcium lost 3.7% (2.4; P < 0.001). A dose-response curve was found between basal BMD and the effect of hormone therapy: women with osteoporosis (T-score <75%) demonstrated the largest increase in BMD - 6.3% (4.6), osteopenia (T-score 75-85%) was associated with a gain of 3.2% (5.6), low-borderline values (T-score 86-100%) gave a modest increase of 1.3% (4.3), and those with more than average BMD values (T-score >100%) actually lost bone despite hormone treatment [-2.1% (4.1)]. CONCLUSIONS: All hormone regimens had a similar bone conserving effect. Basal BMD value may serve as a predictor for the success of treatment. Calcium supplementation should be recommended in all postmenopausal women.

Body Weight↗
PubMed1999

L-thyroxine prevents the bone-conserving effect of HRT in postmenopausal women with subclinical hypothyroidism.

Hypothyroidism, which is a common disorder among postmenopausal women, may be associated with higher than average bone mineral content. Contrarily, treatment with L-thyroxine may cause a significant bone loss. The aim of our study was to evaluate the effects of hormone-replacement therapy (HRT) on bone density in women with subclinical hypothyroidism treated with L-thyroxine. A total of 73 postmenopausal women with thyroid-stimulating hormone (TSH) levels > 5 mU/l and normal free thyroxine values, who never used HRT or L-thyroxine, were divided into three groups according to the treatment given during a 3-year follow-up period: 34 women received only HRT; 20 women received HRT and L-thyroxine, and the remaining 19 women received neither medications. A euthyroid control group included 41 postmenopausal women with TSH levels between 0.5 and 1.5 mU/l, who were using HRT since the initial visit. Lumbar spine bone density measurements were performed at baseline and study termination. Taken as a whole, the hypothyroid women had a non-significant higher baseline bone mineral density (BMD) as compared to the euthyroid controls (1.068 +/- 0.19 g/cm2 vs. 1.024 +/- 0.15). After 3 years, both the euthyroid and hypothyroid women on HRT only had an increase in BMD (0.032 +/- 0.04 g/cm2 and 0.028 +/- 0.05 g/cm2, respectively; p < 0.001 for both, compared to baseline). Hypothyroid women using no medication had a decrease of 0.034 +/- 0.07 g/cm2 in BMD, and those receiving both HRT and L-thyroxine lost the most: 0.04 +/- 0.08 g/cm2 (p < 0.05 for both, compared to baseline). The addition of L-thyroxine thus prevented the beneficial effect of HRT on BMD. Thyroid hormone replacement is recommended only when overt symptoms of hormone deficiency occur. In such cases, a single bone-conserving treatment with HRT may not suffice.

Adult↗
PubMed1998

Hormone replacement and simvastatin in the therapy of hypercholesterolemic postmenopausal women.

OBJECTIVES: To prospectively investigate the effect of cholesterol lowering diet, hormone replacement therapy and simvastatin on plasma lipid levels using a 3-month stepwise protocol. METHODS: Participants were postmenopausal women under the age of 60 with hypercholesterolemia (plasma total cholesterol > 240 mg/dl). The study started with 3 months of Step-One diet (phase I) followed by 3 months of diet and hormone replacement therapy (0.625 mg conjugated estrogens daily combined with 5 mg medroxyprogesterone acetate at days 13-25 of each cycle) (phase II). In women whose total cholesterol remained above 240 mg/dl or LDL-cholesterol above 160 mg/dl by the end of phase II, simvastatin at 10 mg daily was added (phase III). Plasma cholesterol levels as well as safety measurements were closely monitored. RESULTS: Sixteen (21%) of 75 patients who entered the study had satisfactory cholesterol levels by the end of 6 months. Another 25 patients (33%) dropped out of the study for various reasons by that time. In the 34 patients who started simvastatin, plasma total cholesterol levels did not significantly change during phase I and II, however, LDL-cholesterol significantly decreased (204 +/- 31 to 187 +/- 26 mg/dl, p = 0.04) and HDL increased (53 +/- 12 to 62 +/- 16 mg/dl, p = 0.04). A dramatic decrease occurred in both total and LDL-cholesterol levels after one month of phase III (281 +/- 26 to 213 +/- 30 mg/dl 187 +/- 26 to 122 +/- 30 mg/dl respectively, p < 0.0001), with no further changes during the rest of the study period. No significant changes occurred in HDL-cholesterol and triglyceride plasma levels at this phase. Adverse effects were few and minor throughout the study. CONCLUSIONS: Some of the hypercholesterolemic postmenopausal women will benefit from hormone replacement therapy as a single cholesterol lowering treatment in addition to diet (21% in our series). Nevertheless, combination therapy of estrogens and low dose simvastatin proved to be extremely effective in lowering cholesterol levels with no significant side effects. Such therapeutic regimen may also have a synergistic anti-atherogenic effect.

Anticholesteremic Agents↗
PubMed1998

The effects of sublingual estradiol on left ventricular function at rest and exercise in postmenopausal women: an echocardiographic assessment.

OBJECTIVE: To evaluate the acute hemodynamic effects of 4 mg estradiol given sublingually. DESIGN: Rest and exercise echocardiographies were performed prior to estradiol administration. Then, another set of tests was done post-dose: rest examination at 1 h post-dose, isometric exercise at 65 min post-dose, and dynamic exercise at 100 min post-dose. RESULTS: The administration of 4 mg sublingual estradiol to 24 postmenopausal women (aged 48-58 years) was followed 60 min post-dose by a surge in mean estradiol serum levels (1759 +/- 704 pg/ml). At rest a slight drop in systolic and diastolic blood pressure was measured after estrogen ingestion: 132 +/- 24 mm Hg versus 127 +/- 21 mm Hg, p < 0.05; 83 +/- 11 mm Hg versus 78 +/- 10 mm Hg, p < 0.02. There were no changes in resting heart rate, double product, or vascular resistance. The left heart cavities became smaller: the left atrium diameter decreased from 33.7 +/- 4 mm to 32.3 +/- 4 mm, p < 0.01; the end-systolic diameter decreased from 24.9 +/- 3 mm to 23.6 +/- 4 mm, p < 0.01; the end-diastolic diameter decreased from 44.5 +/- 4 mm to 42.7 +/- 4 mm, p < 0.01. The peak aortic blood flow velocity fell from 120 +/- 19 cm/s to 116 +/- 22 cm/s (p < 0.05), and the flow velocity integral fell from 26.3 +/- 4 cm to 24.9 +/- 5 cm (p < 0.01); the cardiac output underwent a small change, with borderline significance: 7 +/- 2 L/min versus 6.7 +/- 2 L/min, p = 0.06. Only minor changes in the hemodynamic and echocardiographic parameters were recorded after estrogen for both isometric and dynamic exercises. Analyses were also made for two subgroups: 13 normotensive women were compared with 11 hypertensive women. The post-estrogen decreases in resting blood pressure and in peak blood velocity were observed only in the hypertensive subjects, whereas the changes in heart dimensions and in flow velocity integral were the same in both subgroups. CONCLUSIONS: Sublingual estradiol was associated with acute hemodynamic alterations mainly at rest but also after exercise.

Administration, Sublingual↗
PubMed1996

Exercise echocardiography in postmenopausal hormone users with mild systemic hypertension.

Rest and exercise echocardiography (at dynamic and isometric exercise) were performed in 30 postmenopausal women (aged 54 +/- 4 years) with borderline to mild hypertension. They were then divided into 2 groups: 17 women who started oral hormone replacement therapy (0.625 mg/day conjugated estrogens or 2 mg/day estradiol) and a control group of 13 nonusers. After 6 to 9 months, a second echocardiography was performed in 26 women (4 withdrew). There were only a few changes in values obtained in the 12 controls at the end of follow-up compared with baseline. Primarily, these changes included a slight decrease in systolic blood pressure at rest and on exercise. Several significant morphologic and hemodynamic alterations appeared in 14 hormone users. Left ventricular cavity dimensions and mass became smaller: mean end-diastolic diameter decreased from 45.9 +/- 3 mm at baseline to 44.4 +/- 3 mm at study termination (p = 0.007). The corresponding values for end-systolic diameter were 25.8 +/- 4 mm and 23.9 +/- 4 mm (p = 0.006); for left atrium diameter, it was 34.5 +/- 4 mm and 32.5 +/- 4 mm (p = 0.001); for left ventricular wall width, it was 19.9 +/- 2 mm and 19.3 +/- 2 mm (p = 0.02); for left ventricular mass, it was 197 +/- 28 g and 179 +/- 32 g (p = 0.006). The resting aortic blood flow velocity and acceleration increased: 119 +/- 18 cm/s before therapy versus 129 +/- 23 cm/s while on hormone substitution (p = 0.04), and 13.6 +/- 3 m/s2 versus 16.5 +/- 4 m/s2 (p = 0.008), respectively. Mean rest to peak exercise systolic blood pressure difference became smaller after hormones: 39 +/- 19 mm Hg versus 28 +/- 13 mm Hg (p = 0.03) during dynamic exercise, and 43 +/- 22 mm Hg versus 25 +/- 13 mm Hg (p = 0.004) during isometric exercise. The above data probably indicate that with hormone replacement therapy, there is an improvement in cardiac function both at rest and during exercise.

Echocardiography, Doppler↗
PubMed1996

Prediction of renal impairment in elderly patients with congestive heart failure treated with captopril.

This study assessed the usefulness of the oral captopril test in the prediction of renal impairment among elderly patients with congestive heart failure (CHF). Forty-seven patients aged > or = 65 years with CHF (EF < 40%) participated in a prospective nonrandomized series. Blood samples for plasma renin activity (PRA) were drawn before and 60 minutes after 50 mg of oral captopril. Twenty-four hours later, captopril was administered (up to 75 mg/day over a 4 day period), and renal laboratory and clinical assessment were performed at baseline and for a 9 day period. In 7 of 47 patients (14.9%), deterioration of renal function was observed. During the captopril test, the PRA increased significantly after 1 hour in almost all patients and the mean blood pressure decreased from 99.2 +/- 14.6 mmHg to 92.2 +/- 13.7 mmHg (p < 0.001). All patients whose baseline PRA level was < 1.9 ng/ml/hr and whose stimulated PRA was < 3.2 ng/ml/hr maintained a stable renal function throughout the study period. Significant statistical correlation (p < 0.05) was found between the initial PRA, the changes in PRA or mean blood pressure during the captopril test, and the change in plasma creatinine and creatinine clearance in the entire group, and was even more evident in a subgroup of patients with an ejection fraction > or = 30%. All these correlations were not statistically significant in the patients with an ejection fraction < 30%. It is thus concluded that measurement of pretreatment PRA levels might be a useful laboratory tool for predicting the renal safety of captopril use in patients with CHF whose EF > or = 30%.

Administration, Oral↗
PubMed1996

A comparison of the inhibitory effect of cromoline and nedocromil Na on histamine release from airway metachromatic cells and from peripheral basophils.

Metachromatic cells are increased in the airways of asthmatic patients. We obtained metachromatic cells from asthmatic airways using an induced sputum technique. The histamine release following ConA, anti-IgE and anti-IgE + IL3 from those cells were evaluated before and following the addition of cromoline Na and nedocromil Na. Metachromatic cells had a higher rate of spontaneous histamine release when compared to peripheral basophils. Cromoline Na and nedocromil Na inhibited histamine release from triggered metachromatic cells but not from peripheral basophils. It is concluded that airway metachromatic cells from asthmatics behave differently than peripheral basophils.

Adult↗