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Biomedical subjects

A Maran

Publications and source records attributed to A Maran.

At least 19 recordsLinked to original sources
PubMed2006

2-methoxyestradiol inhibits differentiation and is cytotoxic to osteoclasts.

2-Methoxyestradiol (2-ME), a naturally occurring metabolite of 17beta-estradiol, is highly cytotoxic to a wide range of tumor cells but is harmless to most normal cells. However, 2-ME prevented bone loss in ovariectomized rats, suggesting it inhibits bone resorption. These studies were performed to determine the direct effects of 2-ME on cultured osteoclasts. 2-ME (2 microM) reduced osteoclast number by more than 95% and induced apoptosis in three cultured osteoclast model systems (RAW 264.7 cells cultured with RANKL, marrow cells co-cultured with stromal support cells, and spleen cells cultured without support cells in media supplemented with RANKL and macrophage colony stimulating factor (M-CSF)). The 2-ME-mediated effect was ligand specific; 2-hydroxyestradiol (2-OHE), the immediate precursor to 2-ME, exhibited less cytotoxicity; and 2-methoxyestrone (2-MEOE1) the estrone analog of 2-ME, was not cytotoxic. Co-treatment with ICI 182,780 did not antagonize 2-ME, suggesting that the cytotoxicity was not estrogen receptor-dependent. 2-ME-induced cell death in RAW 264.7 cells coincided with an increase in gene expression of cytokines implicated in inhibition of differentiation and induction of apoptosis. In addition, the 2-ME-mediated decrease in cell survival was partially inhibited by anti-lymphotoxin(LT)beta antibodies, suggesting that 2-ME-dependent effects involve LTbeta. These results suggest that 2-ME could be useful for treating skeletal diseases in which bone resorption is increased, such as postmenopausal osteoporosis and cancer metastasis to bone.

2-Methoxyestradiol↗
PubMed2006

Effects of stable transfection of human fetal osteoblast cells with estrogen receptor-alpha on regulation of gene expression by tibolone.

Tibolone is a synthetic steroid which undergoes tissue selective metabolism into several metabolites having estrogenic, progestogenic or androgenic activities. The effects of 3 alpha-hydroxy tibolone (Org 4094), 3 beta-hydroxy tibolone (Org 30126) and their sulfated metabolites were investigated on human fetal osteoblasts (hFOB). Tibolone had no effect on selected osteoblast marker proteins in estrogen-receptor negative hFOB cells. In contrast, 3 alpha-hydroxy and 3beta-hydroxy tibolone resulted in dose-dependent increases in alkaline phosphatase activity in estrogen receptor (ER) alpha-positive hFOB cells. The maximum increase for both metabolites was comparable to the effects of an optimal dose of 17beta-estradiol, and occurred at 10 muM. At 20 muM, both metabolites increased mRNA levels for alkaline phosphatase and type 1 collagen and protein levels for osteocalcin. Sulfated metabolites of tibolone also increased alkaline phosphatase activity. The estrogen receptor antagonist ICI 182, 780 inhibited stimulation of alkaline phosphatase activity by sulfated and non-sulfated tibolone metabolites, but was more potent on the former. Taken together, these results suggest that stable transfection of ER alpha into hFOB cells confers regulation by 3 alpha-hydroxy and 3beta-hydroxy tibolone metabolites of osteoblast metabolism.

Alkaline Phosphatase↗
PubMed2004

Role of anti-granulocyte Fab' fragment antibody scintigraphy (LeukoScan) in evaluating bone infection: acquisition protocol, interpretation criteria and clinical results.

Scintigraphy using anti-granulocyte Fab' fragment (LeukoScan) was performed in a series of 220 consecutive patients with suspected bone infection referred to our centre between September 1999 and June 2002. Two protocols were compared for interpreting scans: (1) evaluation of early 4 h imaging alone (protocol A), and (2) evaluation both of early and delayed 24 h imaging (protocol B). Protocol A and protocol B showed equal values of sensitivity (91.9% in patients with diabetic foot and 84.2% in patients with joint prosthesis/peripheral bone implants). Conversely, specificity was higher adopting protocol B than protocol A: 87.5% vs 75.0% in patients with diabetic foot, and 85.7% vs 76.2% in patients with joint prosthesis/peripheral bone implants, respectively. In particular, an improvement in specificity using protocol B was found in those patients with infection and with only a mild LeukoScan uptake in the early 4 h imaging: in these patients an increasing uptake intensity pattern observed in the delayed 24 h imaging was indicative of infection while a decreasing pattern suggested a negative result. Instead, the evidence of a high uptake intensity in the early LeukoScan imaging was a strong indicator of infection and delayed imaging in these cases did not further improve specificity. In conclusion, in our experience, LeukoScan showed high sensitivity in diagnosing bone infection in patients with diabetic foot and joint prosthesis or other peripheral bone implants. Moreover, in patients with an early high LeukoScan uptake intensity further delayed images appears unnecessary for the purpose of diagnosing infection. In contrast in patients with an early mild LeukoScan uptake intensity only, delayed imaging appears to be recommendable for improving specificity.

Adult↗
PubMed2003

Unanticipated changes in steady-state mRNA levels for glyceraldehyde-3-phosphate dehydrogenase in rat tibiae.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA levels are commonly used as an internal control to normalize gene expression data based on the belief that this gene is constitutively expressed. However, GAPDH mRNA levels increased by more than 2.5-fold in tibiae of hindlimb unloaded female rats compared to L32 mRNA levels. Similarly, GAPDH mRNA levels increased compared to 18S ribosomal RNA. Treatment with growth hormone and alcohol show no disparity in GAPDH mRNA levels whereas in some experiments, parathyroid hormone and 17beta-estradiol increased GAPDH mRNA levels. Taken together, these findings indicate that it is essential to demonstrate that GAPDH expression is not altered prior to using the gene as an internal control.

Animals↗
PubMed2003

A microdialysis technique for continuous subcutaneous glucose monitoring in diabetic patients (part 2).

The aim of this study was to evaluate the reproducibility, the accuracy and the reliability of a continuous subcutaneous glucose measuring system. The GlucoDay system (A. Menarini I.F.R. S.r.l.-Florence, Italy) is a portable instrument provided with a micro-pump and a biosensor, coupled to a microdialysis system (see part 1). This instrument has demonstrated high reliability coupled with a low degree of invasivity. The profiles of glucose monitoring allow to achieve an excellent knowledge of the real variation of glucose in diabetic patients. The reproducibility study showed a bias lower than 10% between instruments. The accuracy study showed a difference from the reference method lower than 15%.

Biosensing Techniques↗
PubMed2003

Measurement of gene expression following cryogenic mu-CT scanning of human iliac crest biopsies.

An important consideration in interpreting indices of gene expression in human bone is relating mRNA levels to functional endpoints such as bone architecture. In the present study, a method was developed for quantitative measurement of gene expression and bone morphology in the same specimen. Three-dimensional images of iliac crest bone biopsies from healthy premenopausal women were obtained using a novel high resolution cryogenic mu-CT scanner. RNA was isolated from the biopsies and mRNA levels were measured for genes related to bone metabolism. The gene expression profile and variability of expression within iliac crest biopsies of women was similar to human osteoblastic cell lines and rat long bones. mRNA for alkaline phosphatase, bone matrix proteins, and selected cytokines and cytokine receptors were consistently detected in biopsies. As previously shown in rat bone, there was a tight correlation between mRNA levels for type 1 collagen and osteonectin, a weaker correlation between type 1 collagen and osteocalcin and no correlation between bone matrix proteins and alkaline phosphatase. The relative abundance of the mRNA for the three most prevalent transforming growth factor-beta (TGF-beta) isoforms in bone (TGF-beta(1)>> TGF-beta(3)> TGF-beta(2)) was the same as the known abundance of the corresponding TGF-beta peptides in bone matrix. The results demonstrate the feasibility of analyzing the three-dimensional architecture of a bone biopsy using cryogenic mu-CT imaging and then measuring expression of genes related to bone cell function within the same specimen following RNA extraction and analysis.

Journal Article↗
PubMed2002

A telemedicine support for diabetes management: the T-IDDM project.

In the context of the EU funded Telematic Management of Insulin-Dependent Diabetes Mellitus (T-IDDM) project, we have designed, developed and evaluated a telemedicine system for insulin dependent diabetic patients management. The system relies on the integration of two modules, a Patient Unit (PU) and a Medical Unit (MU), able to communicate over the Internet and the Public Switched Telephone Network. Using the PU, patients are allowed to automatically download their monitoring data from the blood glucose monitoring device, and to send them to the hospital data-base; moreover, they are supported in their every day self monitoring activity. The MU provides physicians with a set of tools for data visualization, data analysis and decision support, and allows them to send messages and/or therapeutic advice to the patients. The T-IDDM service has been evaluated through the application of a formal methodology, and has been used by European patients and physicians for about 18 months. The results obtained during the project demonstration, even if obtained on a pilot study of 12 subjects, show the feasibility of the T-IDDM telemedicine service, and seem to substantiate the hypothesis that the use of the system could present an advantage in the management of insulin dependent diabetic patients, by improving communications and, potentially, clinical outcomes.

Blood Glucose Self-Monitoring↗
PubMed2002

2-methoxyestradiol induces interferon gene expression and apoptosis in osteosarcoma cells.

2-Methoxyestradiol (2-ME), a naturally occurring mammalian metabolite of 17beta-estradiol, has been implicated as a physiological inhibitor of tumor cell proliferation. In this study, the effects of 2-ME on cultured osteosarcomatous cells were investigated. Dose-dependent growth inhibition was observed in MG63 and TE85 human osteosarcoma cells exposed to 2-ME. The cell killing by 2-ME was ligand-specific; the immediate precursor (2-hydroxyestradiol), the parent compound (17beta-estradiol), and the equivalent metabolite of estrone (2-methoxyestrone) exhibited less potency and efficacy. Furthermore, 2-ME was similarly effective at killing immortalized human fetal osteoblastic cells (hFOB) with and without estrogen receptor-alpha and -beta and rat osteosarcoma cells (ROS17/2.8). The cytotoxicity of 2-ME was selective to transformed and immortalized osteoblastic cells; 2-ME (2 microm) had no effect on the proliferation of primary cultures of human osteoblasts. Co-treatment with the potent estrogen receptor ligand, ICI-182,780, did not reduce 2-ME-induced osteosarcoma cell death, implying that this action is not mediated by conventional estrogen receptors. The expression levels of bone matrix protein genes, type 1 collagen and osteonectin, were transiently reduced after 2-ME treatment, suggesting that the surviving cells are capable of producing bone matrix. The 2-ME-mediated killing of osteosarcoma cells was due to the induction of apoptosis; treatment induced expression of interferon genes within 12 h and histological evidence of apoptosis within 48 h of 2-ME treatment. Thus, our results demonstrate that 2-ME is highly cytotoxic to osteosarcoma cells but not normal osteoblasts. These findings suggest that further study of 2-ME as a potential intervention for treatment of osteosarcoma is warranted.

2-Methoxyestradiol↗
PubMed2001

Animal models for osteoporosis.

Animal models will continue to be important tools in the quest to understand the contribution of specific genes to establishment of peak bone mass and optimal bone architecture, as well as the genetic basis for a predisposition toward accelerated bone loss in the presence of co-morbidity factors such as estrogen deficiency. Existing animal models will continue to be useful for modeling changes in bone metabolism and architecture induced by well-defined local and systemic factors. However, there is a critical unfulfilled need to develop and validate better animal models to allow fruitful investigation of the interaction of the multitude of factors which precipitate senile osteoporosis. Well characterized and validated animal models that can be recommended for investigation of the etiology, prevention and treatment of several forms of osteoporosis have been listed in Table 1. Also listed are models which are provisionally recommended. These latter models have potential but are inadequately characterized, deviate significantly from the human response, require careful choice of strain or age, or are not practical for most investigators to adopt. It cannot be stressed strongly enough that the enormous potential of laboratory animals as models for osteoporosis can only be realized if great care is taken in the choice of an appropriate species, age, experimental design, and measurements. Poor choices will results in misinterpretation of results which ultimately can bring harm to patients who suffer from osteoporosis by delaying advancement of knowledge.

Animals↗
PubMed2001

The dose-response effects of ethanol on the human fetal osteoblastic cell line.

Alcohol is a risk factor for the development of osteoporosis, especially in men. Chronic alcohol abuse decreases bone mass, which contributes to the increased incidence of fractures. To better understand the mechanism of action of ethanol on bone metabolism, we have studied the dose-response effects of ethanol on conditionally immortalized human fetal osteoblasts (hFOB) in culture. Ethanol treatment had no significant effects on osteoblast number after 1 day or 7 days. Ethanol treatment did not reduce type I collagen protein levels at either time point at any dose but slightly reduced alkaline phosphatase activity after 7 days. The messenger RNA (mRNA) levels for alkaline phosphatase, type I collagen, and osteonectin were unaltered by 24 h of ethanol treatment but a high dose (200 mM) reduced mRNA levels for the two bone matrix proteins after 7 days. Ethanol treatment led to dose-dependent increases in transforming growth factor beta1 (TGF-beta1) mRNA levels and decreases in TGF-beta2 mRNA levels. The concentration of ethanol in the medium decreased with time because of evaporation but there was little degradation caused by metabolism. These results, which show that cultured osteoblasts are less sensitive than osteoblasts in vivo, suggest that the pronounced inhibitory effects of ethanol on bone formation are not caused by direct cell toxicity.

Alkaline Phosphatase↗
PubMed2001

An integrated approach to assess structure-to-function relationships in the skeleton.

In general, the disciplines of biomechanics, morphology, densitometry, biochemistry, cell biology and molecular biology have advanced independently of one another. In spite of this fragmentation, there have been incremental increases in our understanding of the organization, mechanical properties, growth, remodeling and repair of the tissues comprising the skeleton. As a practical application, this increased knowledge has greatly improved our capabilities for early diagnosis of bone loss and has proven similarly useful in determining the efficacy of interventions to prevent osteoporosis. This approach, however, has been much less successful in countering several other important musculoskeletal disorders, including arthritis. In the immediate future, a major emphasis will be placed on tissue regeneration (engineering) to restore lost mechanical function to a compromised skeleton. To accomplish this goal, it will be necessary to employ much more sophisticated approaches toward evaluating the structure-to-function relationships, ones which will include integration of the respective contributions of gene expression, cell number and activity, matrix composition and architecture to achieve adequate tissue function.

Journal Article↗
PubMed2000

Brain function rescue effect of lactate following hypoglycaemia is not an adaptation process in both normal and type I diabetic subjects.

AIMS/HYPOTHESIS: We have previously shown that lactate protects brain function during insulin-induced hypoglycaemia. An adaptation process could, however, not be excluded because the blood lactate increase preceded hypoglycaemia. METHODS: We studied seven healthy volunteers and seven patients with Type I (insulin-dependent) diabetes mellitus with a hyperinsulinaemic (1.5 mU.kg-1.min-1) stepwise hypoglycaemic clamp (4.8 to 3.6, 3.0 and 2.8 mmol/l) with and without Na-lactate infusion (30 mumol.kg-1.min-1) given after initiation of hypoglycaemic symptoms. RESULTS: The glucose threshold for epinephrine response was similar (control subjects 3.2 +/- 0.1 vs 3.2 +/- 0.1, diabetic patients = 3.5 +/- 0.1 vs 3.5 +/- 0.1 mmol/l) in both studies. The magnitude of the response was, however, blunted by lactate infusion (AUC; control subjects 65 +/- 28 vs 314 +/- 55 nmol/l/180 min, zenith = 2.6 +/- 0.5 vs 4.8 +/- 0.7 nmol/l, p < 0.05; diabetic patients = 102 +/- 14 vs 205 +/- 40 nmol/l/180 min, zenith = 1.4 +/- 0.4 vs 3.2 +/- 0.3 nmol/l, p < 0.01). The glucose threshold for symptoms was also similar (C = autonomic 3.0 +/- 0.1 vs 3.0 +/- 0.1, neuroglycopenic = 2.8 +/- 0.1 vs 2.9 +/- 0.1 mmol/l, D = autonomic 3.2 +/- 0.1 vs 3.2 +/- 0.1, neuroglycopenic 3.1 +/- 0.1 vs 3.2 +/- 0.1 mmol/l) but peak responses were significantly attenuated by lactate (score at 160 min C = 2.6 +/- 1 vs 8.8 +/- 1, and 0.4 +/- 0.4 vs 4.8 +/- 1, respectively; p = 0.02-0.01, D = 1.3 +/- 0.5 vs 6.3 +/- 1.7, and 2.3 +/- 0.6 vs 5.7 +/- 1.1 p = 0.07-0.02). Cognitive function deteriorated in both studies at similar glucose thresholds (C = 3.1 +/- 0.1 vs 3.0 +/- 0.1, D = 3.2 +/- 0.1 vs 3.3 +/- 0.2 mmol/l). Although in normal subjects a much smaller impairment was observed with lactate infusion (delta four-choice reaction time at 160 min = 22 +/- 12 vs 77 +/- 31 ms; p = 0.02), in Type I diabetic patients lactate infusion was associated with an improvement in cognitive dysfunction (0.2 +/- 0.4 vs -38 +/- 0.2 delta ms, p = 0.0001). CONCLUSION/INTERPRETATION: A blood lactate increase after the development of hypoglycaemic symptoms reduces counterregulatory and symptomatic responses to insulin-induced hypoglycaemia and favours brain function rescue both in normal and diabetic subjects. These findings confirm that lactate is an alternative substrate to glucose for cerebral metabolism under hypoglycaemic conditions.

Acclimatization↗
PubMed2000

Mechanisms of acute and chronic hypoglycemic action of gliclazide.

An extrapancreatic effect of sulfonylureas has been postulated. However, in vivo results have been disputed because the amelioration of insulin action that follows sulfonylurea may represent the relief from glucose toxicity rather than a direct effect of the drug. Therefore, we studied the hypoglycemic action of gliclazide acutely and after 2 months of therapy in seven type 2 diabetic patients. All patients received a 240-minute i.v. glucose infusion with [3-3H]glucose. In a random order, 160 mg gliclazide (study 1) or placebo (study 2) was given orally before glucose infusion. Finally, the effect of 160 mg gliclazide was reassessed after a two-month treatment with the same sulfonylurea (80 mg t.i.d.). Basal plasma glucose, insulin, C-peptide and endogenous glucose production (EGP) were similar before the two initial studies. During glucose infusion, EGP was more suppressed after gliclazide in spite of comparable increase in plasma insulin and C-peptide. After the two-month therapy, basal plasma glucose levels and HbA1c were lower while plasma insulin and C-peptide were higher with respect to baseline (p < 0.05). Gliclazide further reduced plasma glucose, the incremental area above baseline, and EGP during glucose infusion, while plasma insulin and C-peptide achieved higher plateaus (p < 0.05). When data were pooled, plasma glucose concentration and EGP correlated both in the basal state (r = 0.71) and during the last hour of glucose infusion (r = 0.84; both p < 0.05). These data suggest that gliclazide enhances the suppression of EGP induced by insulin and that this effect is greater with chronic treatment because of concomitant improvement of insulin secretion.

Acute Disease↗
PubMed1999

Estrogen has rapid tissue-specific effects on rat bone.

The decrease in cancellous bone formation after estrogen treatment is generally thought to be coupled with a prior decrease in bone resorption. To test the possibility that estrogen has rapid tissue-specific actions on bone metabolism, we determined the time course (1-32 h) effects of diethylstilbestrol on steady-state mRNA levels for immediate-response genes, extracellular matrix proteins, and signaling peptides in the proximal tibial metaphysis and uterus by using Northern blot and RNase protection assays. The regulation of signaling peptides by estrogen, although tissue specific, followed a similar time course in bone and uterus. The observed rapid decreases in expression of insulin-like growth factor I, a growth factor associated with bone formation; decreases in mRNA levels for bone matrix proteins; evidence for reduced bone matrix synthesis; failure to detect rapid increases in mRNA levels for signaling peptides implicated in mediating the inhibitory effects of estrogen on bone resorption (interleukin-1 and -6) as well as other cytokines that can increase bone resorption; and the comparatively long duration of the bone remodeling cycle in rats indicate that estrogen can decrease bone formation by a mechanism that does not require a prior reduction in bone resorption.

Animals↗
PubMed1999

Is resveratrol an estrogen agonist in growing rats?

Trans-3,4,5-trihydroxystilbene (resveratrol), a polyphenolic compound found in juice and wine from dark-skinned grape cultivars, was recently shown to bind to estrogen receptors in vitro, where it activated transcription of estrogen-responsive reporter genes. The purpose of this 6-day study in weanling rats was to determine the dose response (1, 4, 10, 40, and 100 microg/day) effects of orally administered resveratrol on estrogen target tissues. The solvent (10% ethanol) had no significant effect on any measurement or derived value. 17Beta-estradiol treatment (100 microg/day) decreased the growth rate, final body weight, serum cholesterol, and radial bone growth (periosteal bone formation and mineral apposition rates) at the tibia-fibula synostosis. In the uterus, 17beta-estradiol treatment increased wet weight, epithelial cell height, and steady state messenger RNA levels for insulin-like growth factor I. In contrast, resveratrol treatment had no significant effect on body weight, serum cholesterol, radial bone growth, epithelial cell height, or messenger RNA levels for insulin-like growth factor I. Resveratrol treatment resulted in slight increases in uterine wet weight, but significance was achieved at the 10-microg dose only. A second experiment was performed to determine whether a high dose of resveratrol (1000 microg/day) antagonizes the ability of estrogen to lower serum cholesterol. As was shown for the lower doses, resveratrol had no effect on body weight, uterine wet weight, uterine epithelial cell height, cortical bone histomorphometry, or serum cholesterol. 17Beta-estradiol significantly lowered serum cholesterol, and this response was antagonized by cotreatment with resveratrol. These in vivo results suggest, in contrast to prior in vitro studies, that resveratrol has little or no estrogen agonism on reproductive and nonreproductive estrogen target tissues and may be an estrogen antagonist.

Administration, Oral↗
PubMed1999

Effect of acute ketosis on the endothelial function of type 1 diabetic patients: the role of nitric oxide.

In type 1 diabetic patients, acute loss of metabolic control is associated with increased blood flow, which is believed to favor the development of long-term complications. The mechanisms for inappropriate vasodilation are partially understood, but a role of endothelium-derived nitric oxide (NO) production can be postulated. We assessed, in type 1 diabetic patients, the effect of the acute loss of metabolic control and its restoration on forearm endothelial function in 13 type 1 diabetic patients who were studied under conditions of mild ketosis on two different occasions. In study 1, after basal determination, a rapid amelioration of the metabolic picture was obtained by insulin infusion. In study 2, seven type 1 diabetic patients underwent the same experimental procedure, except that fasting plasma glucose was maintained constant throughout. Basal plasma venous concentrations of nitrites/nitrates (NO2- + NO3-) were determined both before and after intravenous insulin infusion. Endothelium-dependent and -independent vasodilation of the brachial artery was assessed by an intra-arterial infusion of N(G)-monomethyl-L-arginine (L-NMMA) and sodium nitroprusside (SNP), respectively. The same parameters were determined in 13 control subjects at baseline conditions and during a hyperinsulinemic-euglycemic glucose clamp. Baseline forearm blood flow (4.89 +/- 0.86 vs. 3.65 +/- 0.59 ml x (100 ml tissue)(-1) x min(-1)) and NO2- + NO3- concentration (30 +/- 8 vs. 24 +/- 3 micromol/l) were higher in type 1 diabetic patients than in control subjects (P < 0.05). Insulin infusion was associated with lower forearm blood flow and plasma (NO2- + NO3-) concentration (P < 0.05), irrespective of the prevailing glucose levels, as compared with patients under ketotic conditions. The responses to L-NMMA were significantly lower in type 1 diabetic patients during euglycemia and hyperglycemic hyperinsulinemia (-11 +/- 5 and -10 +/- 4%, respectively, of the ratio of the infused arm to the control arm) than in control subjects at baseline (-18 +/- 6%, P < 0.05) and during hyperinsulinemia (-32 +/- 11%, P < 0.01). We conclude that the acute loss of metabolic control is associated with a functional disturbance of the endothelial function characterized by hyperemia and increased NO release during ketosis and blunted NO-mediated vasodilatory response during restoration of metabolic control by intravenous insulin. This functional alteration is unlikely to be explained by hyperglycemia itself.

Acute Disease↗