Biomedical subjects

G Merola

Publications and source records attributed to G Merola.

At least 19 recordsLinked to original sources

PubMed2006

Measuring, modelling and testing ozone exposure, flux and effects on vegetation in southern European conditions--what does not work? A review from Italy.

Ozone (O3) exposure at Italian background sites exceeds UN/ECE concentration-based critical levels (CLe(c)), if expressed in terms of AOT40. Yet the occurrence of adverse effects of O3 on forests and crops is controversial. Possible reasons include (i) ability of response indicators to provide an unbiased estimate of O3 effects, (ii) setting of current CLe(c) in terms of cut-off value and accumulation level, (iii) response functions adopted to infer a critical level, (iv) environmental limitation to O3 uptake and (v) inherent characteristics of Mediterranean vegetation. In particular, the two latter points suggest that critical levels based on accumulated stomatal flux (CLe(f)) can be a better predictor of O3 risk than CLe(c). While this concept is largely acknowledged, a number of factors may limit its applicability for routine monitoring. This paper reviews levels, uptake and vegetation response to O3 in Italy over recent years to discuss value, uncertainty and feasibility of different approaches to risk assessment.

Crops, Agricultural↗

PubMed2000

Response to ambient ozone of two white clover (Trifolium repens L.cv. "Regal") clones, one resistant and one sensitive, grown in a Mediterranean environment.

Two clones of white clover (Trifolium repens L.) differing in ozone tolerance were grown in southern Italy during 1997 and 1998 to study the effects of ambient ozone exposure on yield, leaf morphology and water use. Ambient ozone levels were high in both years with values exceeding the threshold for leaf injury reported in the literature. In both years ozone injury was observed on the sensitive clone (NC-S) but not on the resistant one (NC-R), and leaf and stolon dry matter production was significantly lower in NC-S than in NC-R. However, it cannot be excluded that other factors, such as high temperature, interacted with the effect of ozone on biomass production. The clones differed in morphological characteristics. Lower total leaf area in NC-S plants was due to a smaller number of leaves per plant, but the average area per leaf was higher in NC-S. Specific leaf weight and net assimilation rate were higher in the more productive clone (NC-R). Cumulative plant water use was higher in NC-R in each growth period because of the larger leaf area; by contrast, water use per unit leaf area was higher in NC-S, indicating higher leaf conductance to water vapour. The results suggest that ozone significantly reduces the yield of sensitive white clover plants under well-watered conditions, and that the difference in ozone tolerance between clover clones is related to differences in leaf morphology and water use.

Journal Article↗

PubMed1994

Comparative study of the survival rate of frozen-thawed embryos with perforated zonae from microsurgical fertilization and frozen-thawed embryos with intact zonae.

OBJECTIVE: To compare the survival rate of frozen-thawed embryos with perforated zonae from microsurgical fertilization (subzonal insemination) (SUZI) with that of embryos with intact zonae. DESIGN: Thirty-eight embryos resulting from microsurgical fertilization by SUZI were cryopreserved in 16 patient cycles. Within the same period, 140 zonae-intact embryos from 46 patient cycles were cryopreserved. The survival rate of the SUZI embryos was compared with the zonae-intact embryos after thawing. Clinical pregnancies were compared after the transfer of the thawed embryos. RESULTS: The total survival rates were 94.7% and 89.3% for thawed SUZI embryos and zonae-intact embryos, respectively. Within each type of embryo, total survival rates were similar irrespective of the age of the embryos at freezing. The blastomere loss per thawed embryo was the same for zonae-intact and SUZI embryos. One clinical pregnancy was obtained in patients who received thawed SUZI embryos and nine in patients who received embryos with intact zonae. CONCLUSIONS: It is concluded that SUZI embryos can be cryopreserved and thawed with the same degree of confidence as zonae-intact embryos. The low implantation rate of thawed SUZI embryos requires confirmation in a larger clinical series.

Cryopreservation↗

PubMed1989

Leucine kinetics and the effects of hyperinsulinemia in patients with Cushing's syndrome.

As muscle wasting and resistance to insulin-mediated glucose utilization are features of Cushing's syndrome (CS), we examined glucose and amino acid metabolism in six patients with CS and six normal subjects before and during euglycemic hyperinsulinemic clamp studies (plasma insulin concentrations, approximately 0.36, approximately 0.65, and approximately 10.05 mmol/L). The two groups had similar body mass index values. In the postabsorptive state, leucine and alpha-ketoisocaproate (KIC) rates of appearance (Ra), KIC oxidation, and nonoxidized leucine-carbon flux, an index of leucine entering protein (Leu----P), were comparable in CS patients [2.38 +/- 0.14 (+/- SE), 0.22 +/- 0.04, and 2.16 +/- 0.12 mumol/kg.min) and in normal subjects (2.73 +/- 0.25, 0.17 +/- 0.02, and 2.59 +/- 0.22 mumol/kg.min). During the euglycemic clamp studies the leucine and KIC Ra values, KIC oxidation, and Leu----P decreased to a similar extent in both groups. In contrast, insulin-mediated glucose utilization was impaired in the CS patients at each clamp step (P less than 0.05). In summary, postabsorptive whole body leucine metabolism is normal in patients with CS and is normally suppressed by hyperinsulinemia, indicating a dissociation in insulin sensitivity with respect to glucose and amino acid metabolism.

Adolescent↗

PubMed1987

Corticotropin releasing hormone stimulation test: diagnostic aspects in Cushing's syndrome.

The effect of exogenous ovine Corticotropin-Releasing Hormone (oCRH) on plasma ACTH and cortisol levels was investigated in 10 normal volunteers and in 37 patients with Cushing's syndrome (26 with pituitary-dependent disease, 5 with an adrenal adenoma, 2 with an adrenal carcinoma and 4 with bilateral nodular hyperplasia). In all normal subjects and in patients with Cushing's disease, oCRH 100 micrograms as a bolus produced an increase in both plasma ACTH and cortisol. The peak of ACTH occurred after 15-30 min, while plasma cortisol showed highest levels between 30 and 60 min after oCRH administration. The hormonal response in Cushing's disease showed great variability with a clear hyperresponsiveness at least in 6 out of 26 patients with Cushing's disease. A slight and delayed response occurred in 3 cases of bilateral nodular adrenal hyperplasia, while a fourth case showed hyperresponsiveness similar to that found in pituitary-dependent Cushing's disease. No response was observed in patients with an adrenal tumor. Eleven patients with Cushing's disease were tested before and 1 month after pituitary microadenomectomy. After surgery basal cortisol levels were reduced in 10 and became unresponsive or less responsive to oCRH. ACTH patterns were variable with a normal response only in few cases. Although this test seems of limited value in the diagnosis of hypercortisolism, it is a useful tool to differentiate some types of Cushing's syndrome (adrenal tumor from pituitary-dependent Cushing's disease). Variable patterns of response in cases with bilateral nodular adrenal hyperplasia limit the usefulness of this test in recognizing this rare form of hypercortisolism.

Adolescent↗

PubMed1985

Evidence for ectopic ACTH production years after bilateral adrenalectomy for Cushing's syndrome: in vivo and in vitro studies.

Three patients presented with hyperpigmentation and high plasma levels of ACTH 4-5 years after bilateral adrenalectomy for Cushing's "disease". X-rays and ct-scan of the lungs showed a small pulmonary mass in all. ACTH levels (1100-2000 pg/ml) were not suppressible by high doses hydrocortisone. A carcinoid tumor was removed in two cases and a chemodectoma in the third. Evidence for ACTH secretion by these tumors was provided by both decrease of ACTH levels after surgery and/or in vitro studies. Both carcinoid cultures showed a basal ACTH production, which was clearly increased by LVP (10(-7) M) and CRF (10(-7) M). Our findings in vitro studies suggest the presence of specific receptor sites for physiological stimuli (LVP and CRF) in tumor cell membranes.

Adrenalectomy↗

PubMed1985

Effect of short and long-term administration of lisuride in Cushing's disease.

To define the role of dopaminergic drugs on pituitary ACTH secretion, we studied the effect of a dopamine-agonist, lisuride, on a group of 9 patients with pituitary dependent Cushing's syndrome. Lisuride (0.4-0.6 mg/day) was administered for two days: in only two out of eight cases the ACTH levels, sampled every 30 min for 6 h (08:00-14:00 h), showed some reduction when compared with the control day. Two of the nonresponders (R.P.; B.F.) and one untested patient (L.E.) were then treated chronically with a similar amount of lisuride per day for 20 days (L.E.) and for 4 months (B.F.; R.P.). One patient (L.E.) showed a clear decrease in urinary free cortisol without clinical improvement; while in the other two cases, followed for a longer period of time, a clinical improvement was observed together with a decrease of the hormonal parameters. In conclusion, lisuride may occasionally reduce ACTH secretion in patients with pituitary dependent Cushing's syndrome, but the acute test fails to identify the patients who would benefit from this treatment.

Adrenocorticotropic Hormone↗

PubMed1985

Prolonged treatment of Cushing's disease by ketoconazole.

Ketoconazole, used in clinical practice as an antifungal medication, recently was found to be a potent inhibitor of gonadal and adrenal steroidogenesis in vitro and in vivo. The effects of prolonged treatment with this agent in Cushing's disease were investigated in five patients who had recurrent severe hypercortisolism after selective transsphenoidal surgery. The patients received the drug for at least 2 months. Urinary cortisol markedly decreased in all patients immediately after the beginning of treatment with ketoconazole (800 mg/day) and remained within low normal levels when the daily dose was lowered to 600 mg/day. Plasma cortisol also decreased. After 4-6 weeks of treatment, the clinical features of the disease regressed in all patients without signs of toxicity. These findings indicate that ketoconazole may be a valuable drug for the management of patients with Cushing's disease because of its ability to correct hypercortisolism quickly.

Administration, Oral↗

PubMed1982