Riccardo Ientile

Effects of Genistein and Hormone-Replacement Therapy on Bone Loss in Early Postmenopausal Women: A Randomized Double-Blind Placebo-Controlled Study

The natural isoflavone phytoestrogen genistein has been shown to stimulate osteoblastic bone formation, inhibit osteoclastic bone resorption, and prevent bone loss in ovariectomized rats. However, no controlled clinical trial has been performed so far to evaluate the effects of the phytoestrogen on bone loss in postmenopausal women. We performed a randomized double‐blind placebo‐controlled study to evaluate and compare with hormone‐replacement therapy (HRT) the effect of the phytoestrogen genistein on bone metabolism and bone mineral density (BMD) in postmenopausal women. Participants were 90 healthy ambulatory women who were 47–57 years of age, with a BMD at the femoral neck of <0.795 g/cm2. After a 4‐week stabilization on a standard fat‐reduced diet, participants of the study were randomly assigned to receive continuous HRT for 1 year (n = 30; 1 mg of 17β‐estradiol [E2] combined with 0.5 mg of norethisterone acetate), the phytoestrogen genistein (n = 30; 54 mg/day), or placebo (n = 30). Urinary excretion of pyridinoline (PYR) and deoxypyridinoline (DPYR) was not significantly modified by placebo administration either at 6 months or at 12 months. Genistein treatment significantly reduced the excretion of pyridinium cross‐links at 6 months (PYR = −54 ± 10%; DPYR = −55 ± 13%; p < 0.001) and 12 months (PYR = −42 ± 12%; DPYR = −44 ± 16%; p < 0.001). A similar and not statistically different decrease in excretion of pyridinium cross‐links was also observed in the postmenopausal women randomized to receive HRT. Placebo administration did not change the serum levels of the bone‐specific ALP (B‐ALP) and osteocalcin (bone Gla protein [BGP]). In contrast, administration of genistein markedly increased serum B‐ALP and BGP either at 6 months (B‐ALP = 23 ± 4%; BGP = 29 ± 11%; p < 0.005) or at 12 months (B‐ALP = 25 ± 7%; BGP = 37 ± 16%; p < 0.05). Postmenopausal women treated with HRT had, in contrast, decreased serum B‐ALP and BGP levels either at 6 months (B‐ALP = −17 ± 6%; BGP = −20 ± 9%; p < 0.001) or 12 months (B‐ALP = −20 ± 5%; BGP = −22 ± 10%; p < 0.001). Furthermore, at the end of the experimental period, genistein and HRT significantly increased BMD in the femur (femoral neck: genistein = 3.6 ± 3%, HRT = 2.4 ± 2%, placebo = −0.65 ± 0.1%, and p < 0.001) and lumbar spine (genistein = 3 ± 2%, HRT = 3.8 ± 2.7%, placebo = −1.6 ± 0.3%, and p < 0.001). This study confirms the genistein‐positive effects on bone loss already observed in the experimental models of osteoporosis and indicates that the phytoestrogen reduces bone resorption and increases bone formation in postmenopausal women.

Tissue transglutaminase and the stress response

Summary.The expression of the protein crosslinking enzyme tissue transglutaminase (TG2, tTG), the ubiquitous member of transglutaminase family, can be regulated by multiple factors. Although it has been suggested that TG2 can be involved in apoptotic cell death, high levels of enzyme have also been associated with cell survival in response to different stimuli. Furthermore, evidence indicates that increases in TG2 production cause enzyme translocation to cell membrane. Cell stress can also lead to TG2 accumulation on the cell surface and in the extracellular matrix resulting in changes in cell-matrix interactions.Here, we discuss the underlying mechanisms of TG2 up-regulation induced by various stimuli including glutamate exposure, calcium influx, oxidative stress, UV, and inflammatory cytokines.These findings agree with a postulated role for transglutaminases in molecular mechanisms involved in several diseases suggesting that cross-linking reactions could be a relevant part of the biochemical changes observed in pathological conditions.

Recombinant human erythropoietin stimulates angiogenesis and healing of ischemic skin wounds.

Wound healing in ischemic tissues such as flap margins due to inadequate blood supply is still a source of considerable morbidity in surgical practice. Adequate tissue perfusion is particularly important in wound healing. We investigated the effects of recombinant human erythropoietin (rHuEPO) on wound healing in an ischemic skin wound model. Sixty-three Sprague-Dawley rats were used. Normal incisional wound and H-shaped double flaps were used as the wound models. Animals were treated with rHuEPO (400 IU/kg) or its vehicle. Rats were killed on different days (3, 5, and 10 days after skin injury) and the wounded skin tissues were used for immunohistochemistry and for analysis of vascular endothelial growth factor content and collagen content. Tissue transglutaminase immunostaining of histological specimens was used as a vascular marker to determine the level of microvessel density. The results showed a higher level of vascular endothelial growth factor protein and an increased microvessel density in ischemic wounds with rHuEPO treatment than the normal incisional wounds and ischemic control wounds. Collagen content was higher in the incisional wounds and in the ischemic wounds with rHuEPO treatment compared with the ischemic control wounds. Our results suggest that erythropoietin may be an effective therapeutic approach in improving healing in ischemic skin wounds.

Serum ionized magnesium levels in relation to metabolic syndrome in type 2 diabetic patients.

Objective: To evaluate circulating serum ionized magnesium (i-Mg) concentrations in patients with type 2 diabetes mellitus, and to investigate its relationship with the components of the metabolic syndrome. Design: cross-sectional study. Setting: Outpatients’ service for diabetic patients at the University Hospital of Messina, Italy. Subjects: 290 patients with type 2 diabetes mellitus. Measures of Outcome: Serum i-Mg was measured by ion selective electrode. Age, gender, body mass index (BMI), waist circumference, blood pressure, fasting glucose, HbA1c, HDL cholesterol, triglycerides, and urinary albumin excretion rate (UAER) were considered in the analyses. Patients with hypomagnesemia, defined as serum i-Mg <0.46 mmol/l, were compared with those having normal serum i-Mg levels, and variables proven to be associated with low i-Mg levels in the univariate analysis were entered in a multivariable logistic regression model to obtain a deconfounded estimate of the association between metabolic parameters and hypomagnesemia. Results: In univariate analysis, serum i-Mg levels were significantly reduced in patients with low HDL cholesterol, high triglycerides values, high waist circumference, high blood pressure, microalbuminuria and clinical proteinuria. Hypomagnesemia was highly prevalent in our study population (N = 143, 49.3%). After adjusting for potential confounders, plasma triglycerides (OR = 4.71; 95% CI = 2.56–8.67), waist circumference (OR = 2.21; 95% CI = 1.21–4.04), microalbuminuria (OR = 2.43; 95% CI = 1.16–5.08) and clinical proteinuria (OR = 2.04; 95% CI = 1.02–5.68) were independently associated with hypomagnesemia. Conclusions: Hypomagnesemia is highly prevalent in diabetic outpatients. High plasma triglycerides, waist circumference and albuminuria are independent correlates of hypomagnesemia.

Hyperhomocysteinemia in epileptic patients on new antiepileptic drugs.

Purpose:  Older enzyme‐inducing antiepileptic drugs (AEDs) may induce supraphysiologic plasma concentrations of total (t) homocysteine (Hcy). The aim of the present study was to investigate the effect of new AEDs on plasma tHcy levels.

Leptin-dependent platelet aggregation in healthy, overweight and obese subjects

OBJECTIVE: To investigate the effects of leptin on platelet aggregation and platelet free calcium (Ca2+) concentrations, and the role of the long form of leptin receptor (ObRb) and the phospholipase C (PLC) in mediating leptin effects on platelet function.DESIGN: Cross-sectional, clinical study.SETTING: Outpatients Service for Prevention and Treatment of Obesity at the University Hospital of Messina, Italy.SUBJECTS: A total of 19 healthy, 14 overweight, and 16 obese male subjects.MEASUREMENTS: ADP-induced platelet aggregation and platelet Ca2+ were measured after incubation of platelet-rich plasma with leptin alone 5–200 ng/ml, leptin 200 ng/ml and anti-human leptin receptor long-form antibody (ObRb-Ab) 5–10 μl, or leptin 200 ng/ml and PLC inhibitor U73122 0.5–1 nmol/l.RESULTS: Platelet stimulation with leptin lead to a significant and dose-dependent increase in platelet aggregation in healthy subjects. This effect was blunted in overweight, and strongly reduced in obese subjects. Similarly, the incubation with leptin induced a significant and dose-dependent increase in platelet free calcium, which was blunted in overweight and obese patients. The effect of leptin on platelet aggregation and platelet Ca2+ was completely abated by the anti-ObRb-Ab and the PLC inhibitor U73122.CONCLUSIONS: Leptin produces a dose-dependent enhancement of ADP-induced platelet aggregation in humans. Platelet aggregation response to leptin is blunted, but not completely abolished in overweight/obese subjects, thus suggesting that platelet may represent a site of leptin resistance in human obesity. Leptin increases platelet free calcium in a dose-dependent manner. The inhibition of PLC completely abates the effect of leptin on both platelet aggregation and Ca2+ levels. These findings suggest that signaling pathway other than JAK–STAT tyrosine phosphorylation (ie PLC and calcium) may be involved in mediating the prothrombotic action of leptin.

Serum Ionized Magnesium Levels in Type 2 Diabetic Patients with Microalbuminuria or Clinical Proteinuria

Background/Aims: The association between microalbuminuria and magnesium depletion is a controversial issue, and serum ionized magnesium levels have not been previously studied in patients with different grades of diabetic nephropathy. Therefore, the aim of this study was to evaluate circulating ionized magnesium concentrations in patients with non-insulin-dependent diabetes mellitus (NIDDM) and incipient or overt diabetic nephropathy. Methods: We measured fasting plasma glucose, creatinine, creatinine clearance estimate, total cholesterol and triglycerides, and serum ionized magnesium (ion-selective electrodes, ISE) in 30 NIDDM patients with urinary albumin excretion rate (UAER) <20 μg/min (normoalbuminuria), 30 NIDDM patients with microalbuminuria (20 < UAER < 200 μg/min), 30 NIDDM patients with clinical proteinuria (UAER >200 μg/min), and 20 healthy subjects. Results: Serum ionized magnesium levels were significantly reduced in diabetic patients when compared to control subjects (0.39 ± 0.06 vs. 0.58 ± 0.05 mmol/l, p < 0.001). Moreover, diabetic patients with microalbuminuria or clinical proteinuria showed a significant decrease in serum ionized magnesium with respect to normoalbuminuria group (normoalbuminuria: 0.45 ± 0.02 mmol/l; microalbuminuria: 0.36 ± 0.05 mmol/l, p < 0.001; clinical proteinuria: 0.35 ± 0.04 mmol/l, p < 0.001). Serum ionized magnesium showed a significant negative correlation with plasma HbA1c and triglycerides in both microalbuminuria and clinical proteinuria groups. Multiple linear regression analysis showed that circulating ionized magnesium levels decrease together with the increase of plasma HbA1c and triglycerides in NIDDM patients with incipient or overt nephropathy, also after adjusting for age, sex, BMI, diabetes duration, systolic and diastolic blood pressure, hypoglycemic therapy, plasma creatinine, creatinine clearance, plasma cholesterol and fasting glucose. Conclusions: Microalbuminuria and clinical proteinuria, as well as poor glycometabolic control and hypertriglyceridemia, are associated to relevant alterations in magnesium metabolism, and the measurement of serum ionized magnesium seems to represent a useful biochemical tool for the study of magnesium disturbances in patients with different grades of diabetic nephropathy.

Flavonoid Fraction of Bergamot Juice Reduces LPS-Induced Inflammatory Response through SIRT1-Mediated NF-κB Inhibition in THP-1 Monocytes

Plant polyphenols exert anti-inflammatory activity through both anti-oxidant effects and modulation of pivotal pro-inflammatory genes. Recently, Citrus bergamia has been studied as a natural source of bioactive molecules with antioxidant activity, but few studies have focused on molecular mechanisms underlying their potential beneficial effects. Several findings have suggested that polyphenols could influence cellular function by acting as activators of SIRT1, a nuclear histone deacetylase, involved in the inhibition of NF-κB signaling. On the basis of these observations we studied the anti-inflammatory effects produced by the flavonoid fraction of the bergamot juice (BJe) in a model of LPS-stimulated THP-1 cell line, focusing on SIRT1-mediated NF-κB inhibition. We demonstrated that BJe inhibited both gene expression and secretion of LPS-induced pro-inflammatory cytokines (IL-6, IL-1β, TNF-α) by a mechanism involving the inhibition of NF-κB activation. In addition, we showed that BJe treatment reversed the LPS-enhanced acetylation of p65 in THP-1 cells. Interestingly, increasing concentrations of Sirtinol were able to suppress the inhibitory effect of BJe via p65 acetylation, underscoring that NF-κB–mediated inflammatory cytokine production may be directly linked to SIRT1 activity. These results suggest that BJe may be useful for the development of alternative pharmacological strategies aimed at reducing the inflammatory process.

Apoptosis and necrosis occurring in excitotoxic cell death in isolated chick embryo retina.

Excitotoxic studies using isolated chick embryo retina indicated that such an in vitro model provides a valid tool to characterize the effect of different agonists for subtypes of glutamate ionotropic receptors. In retinas maintained for 24 h in a Krebs medium, after a brief exposure (30 min) to glutamate agonists, we compared the effects produced by NMDA and non‐NMDA‐agonists, such as kainic acid (KA) or α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA). Delayed retinal damage was assessed by measuring lactate dehydrogenase (LDH) present in the medium after exposure to the previously named agonists. Although at high concentrations, both KA and AMPA produced more relevant release than NMDA, 7–8% of total retinal LDH was released after exposure to a 50 µm concentration of non‐NMDA agonists. These values were similar to those obtained after 100 µm NMDA. In this regard, retinal tissue appeared to be less sensitive to excitotoxicity based on the activation of NMDA receptor subtype. All three agents produced histopathological lesions typical for excitotoxic damage. A delayed form of excitotoxicity observed in retina segments was predominated by necrotic features. However, the activation of apoptotic machinery early during the incubation period subsequent to brief exposure to NMDA (100 µm) was also present. The activation of caspase enzymes was studied by a fluorometric protease activity assay as well as by western blot analysis. Caspase‐3‐like activity reached the highest value within 3 h of incubation after exposure to excitotoxin, then the level of enzyme activity declined to lower values. As confirmed by a time‐related appearance of TUNEL‐positive nuclei, apoptotic features appeared to be specific for retina response to NMDA. In contrast, the exposure to a 50 µm concentration of KA or AMPA induced necrotic cell damage which was evident through the incubation, leading to a delayed mechanism of excitotoxicity. These observations provide evidence that in the retinal model, with regard to agonist concentrations and subtype of glutamate receptors, the cascade of events leading to excitotoxicity may result in either apoptotic or necrotic neuronal cell damage.

NITRIC OXIDE SYNTHASE PATTERNS IN NORMAL AND VARICOCELE TESTIS IN ADOLESCENTS

Objective To determine if the testes of normal adolescents can produce nitric oxide (NO), by assessing NO synthase (NOS) activity, and whether this activity changes in adolescents with left idiopathic varicocele.