Study of the response of an ORTEC GMX45 HPGe detector with a multi-radionuclide volume source using Monte Carlo simulations

A model of an n-type ORTEC GMX45 HPGe detector was created using the MCNPX and the MCNP-CP codes. In order to validate the model, experimental efficiency was compared with the Monte Carlo simulations results. The reference source is a NIST traceable multi-gamma volume source in a water-equivalent epoxy resin matrix (1.15gcm(-3) density) containing several radionuclides: (210)Pb, (241)Am, (137)Cs and (60)Co in a cylinder shape container. Two distances of source bottom to end cap front surface of the detector have been considered. The efficiency for the nearest distance is higher than for longer distance. The relative difference between the measured and the simulated full-energy peak efficiency is less than 4.0% except for the 46.5keV energy peak of (210)Pb for the longer distance (6.5%) allowing to consider the model validated. In the absence of adequate standard calibration sources, efficiency and efficiency transfer factors for geometry deviations and matrix effects can be accurately computed by using Monte Carlo methods even if true coincidence could occur as is the case when the (60)Co radioisotope is present in the source.

A1c, glucose variability and hypoglycemia risk in patients with type 1 diabetes

AIM

The aim of this paper was to compare the predictive value of glycated hemoglobin (A1c) and glucose variability (GV) in the risk of hypoglycemia in patients with type 1 diabetes (T1D).

METHODS

Analysis of continuous glucose monitoring performed in 130 T1D patients with a diabetes background of 17.1±8.6 years, in intensive insulin therapy (49.8±17.9 UI per day). Mean interstitial glucose (in mg/dL), GV (standard deviation of mean glucose, in mg/dL), time per day spent in hypoglycemia (interstitial glucose ≤70 mg/dL, in %), and episodes of asymptomatic or nocturnal hypoglycemia, (hypoglycemia between midnight and 8 a.m., in %), were assessed. Patients were divided into two groups: group I (N.=84) with A1C≤7.5% and group II (N.=46) with A1C>7.5%. A statistical analysis was performed using SPSS, version 21.0®.

RESULTS

Group I presented a significantly lower mean glucose (139.2±25.9 vs. 173.1±33.2 mg/dL, P<0.05) and GV (58.4±18.8 vs. 70.3±18.6 mg/dL, P<0.05) and more hypoglycemia time (7.65±7.04 vs. 5.35±5.64%, P<0.05). The number of patients with nocturnal hypoglycemia was not significantly different in both groups (8.7 vs. 5.8%, P>0.05). Hypoglycemia time was positively correlated with GV (r=0.23, P=0.01) and negatively with A1C and mean glucose (r=-0.23 and r=-0.36; P=0.01). In multivariate analysis, GV and mean glucose were associated with hypoglycemia time (β=0.22 and β=-0.15, P<0.01, respectively), independent of A1c, diabetes duration and insulin dose; nocturnal hypoglycemia was only associated with mean glucose (OR=0.9, P<0.05) and was associated with a 16-fold increased risk of asymptomatic hypoglycemia (OR: 16.9, P<0.01).

CONCLUSION

Patients with high HbA1c still remain at risk of hypoglycemia. Glucose variability independently predicts daily time spent in hypoglycemia. At night, hypoglycemia only correlates with mean glucose, suggesting that daily fluctuations are probably due to inadequate meals insulin coverage. The potential of GV for predicting hypoglycemia time supports the inclusion of measures of GV into a global diabetes strategy.

Paternal deprivation prior to adolescence and vulnerability to pituitary adenomas

It has been reported that women with prolactinoma were exposed, early in life, to an environment characterized by an absent or violent father. The present study was designed to evaluate whether paternal absence or violent paternal behavior were more prevalent in patients with pituitary adenomas (prolactinoma, acromegaly, non-secreting adenoma and Cushing's disease) compared to a control population. We conducted an observational case-control multicenter study. We interviewed 395 patients with prolactinoma (296 females and 99 males), 130 with acromegaly (87 females and 43 males), 237 with non-secreting adenoma (144 females and 93 males) and 68 with Cushing's disease (61 females and 7 males) and 365 patients from the same clinics with nodular thyroid disease or lymphocytic thyroiditis with euthyroidism as controls. Violent or absent fathers were significantly more prevalent in patients with prolactinoma or acromegaly than in controls (P = 0.001 and P = 0.002, respectively) but not in patients with non-secreting adenoma or corticotrophinoma. Absent fathers in prolactinoma and acromegaly versus controls: P = 0.001 and P = 0.119. Violent fathers in prolactinoma and acromegaly versus controls: P = 0.069 and P = 0.001. The prevalence of absent or violent fathers was also significantly higher in prolactinoma and acromegaly when compared to non-secreting adenoma (P = 0.039 and P = 0.033, respectively). Paternal deprivation before adolescence may be a risk factor for prolactinoma and acromegaly but not for non-secreting pituitary adenomas or Cushing's disease.

Interim storage of spent and disused sealed sources: optimisation of external dose distribution in waste grids using the MCNPX code

Radioactive sealed sources are in use worldwide in different fields of application. When no further use is foreseen for these sources, they become spent or disused sealed sources and are subject to a specific waste management scheme. Portugal does have a Radioactive Waste Interim Storage Facility where spent or disused sealed sources are conditioned in a cement matrix inside concrete drums and following the geometrical disposition of a grid. The gamma dose values around each grid depend on the drum's enclosed activity and radionuclides considered, as well as on the drums distribution in the various layers of the grid. This work proposes a method based on the Monte Carlo simulation using the MCNPX code to estimate the best drum arrangement through the optimisation of dose distribution in a grid. Measured dose rate values at 1 m distance from the surface of the chosen optimised grid were used to validate the corresponding computational grid model.

Influence of individually estimated portion size on the assessment of nutritional risk in colorectal cancer in Portugal

We evaluated the influence of individually estimated portion sizes on the estimate of nutrient related risk of colorectal cancer, using data from a Portuguese hospital based case-control study on diet and colorectal cancer. A total of 100 patients with colorectal adenocarcinoma (aged 15-92 years) and 211 controls (aged 36-89 years) were included. Two data sets were created for nutrient analysis, the first one allowed estimates of food intake using data on portion size as collected with visual aids during the interview. The second estimate substituted respondents' estimate with a standard portion size, as used in the semi-quantitative (SQ) food frequency approach. The two analytic approaches yielded similar energy and nutrient intakes in cases and controls. The percent range of concordance is acceptable, in the same quartile varying from 44 to 82% (mean: 56%) and very good in the same or adjacent (+/-1) quartile (mean: 91%, range: 85-97%). The two estimates lead to a similar pattern of multivariate odd's ratio, however the SQ estimates resulted in more significant findings. We conclude that little extra information is gained by including individual portion size information when assessing diet-related risk of colorectal cancer.

[Acute thyroiditis]

We review the pathophysiology, clinical features and therapy of acute thyroiditis. Four cases are reported stressing the role of fine needle aspiration for the diagnosis of this clinical entity.

Influence of 0.1 or 0.2% cholesterol-enriched diets on the induction of atherosclerosis and aorta reactivity in vitro

Current knowledge of atherogenesis is largely based on animal models of hypercholesterolemia, which rarely show changes similar to the lesions described in humans. We studied the influence of two low cholesterol-enriched diets on the development of anatomopathologic lesions and on the reactivity of the isolated aorta in rabbits. Compared with controls (rabbits fed a normal diet), a 0.1% cholesterol-enriched diet over a 6- or 9-month period produced increases of the 5-hydroxytryptamine (5-HT)-induced contractile responses, as well as a decreases in acetylcholine (ACh)-induced relaxing response (endothelium-dependent, through the production of NO). Noradrenaline (NA)-induced contractions and relaxations elicited by sodium nitroprusside (SNP; endothelium independent) were not significantly modified. Because at 6 months, significant anatomopathologic intimal early lesions were not found, functional endothelial changes can explain such findings. There was a defect in NO synthesis, release, or diffusion; 5 HT, but not NA, may be responsible for inducing NO production. In 0.2% cholesterol-fed rabbits at 4 and 12 weeks, increases of 5-HT- and NA-induced contractile responses were found. In both cases, there was a decrease of ACh-induced relaxing effect, whereas responses to SNP remained unchanged. Intimal early and advanced lesions were present at both the 4- and 12-week periods. These data suggest abnormalities of the NO system. The effects obtained with NA may be explained by a possible decrease of catechol-O-methyltransferase (COMT) or monoamine oxidase (MAO) activities or both or by decreased amine uptake. The extent to which NA may induce NO production is small, because changes in NA-induced contractions are verified only in the presence of significant alterations in the endothelium. The use of a 0.2% cholesterol diet for a short time may induce atherosclerotic lesions, whereas the 0.1% cholesterol diet for a 9-month period, besides being closer to the human diet, allows the detection of functional abnormalities before the evidence of structural lesions.

[Sarcoma of endometrial stroma (SEE). Clinical and pathological prognostic factors]

Endometrial Stromal Sarcomas are rare neoplasms, accounting for 0.2% of female genital tract malignancies. They occur predominantly in post menopausal women, although they can develop during the reproductive years or even in childhood. The most important prognostic factors are the patient's age at diagnosis, FIGO surgical stage, myometrial invasion, mitotic index, DNA index and tumoral necrosis. In this study we try to evaluate the main prognostic factors in the women treated in the Portuguese Oncology Institute in Oporto. From the study of the 14 patients with the diagnosis of endometrial stromal sarcoma, between 1974 and 1995, we can conclude that the main factors influencing the outcome were FIGO surgical staging, mitotic index and myometrial invasion.

[The prevalence of hypertension in acromegaly]

AIM

To estimate the prevalence of hypertension (HT) in a group of patients with acromegaly at the moment of diagnosis and after treatment.

PATIENTS AND METHODS

Fifty-seven patients, 43 females and 14 males with a mean age of 45.19 +/- 11.9 years were studied retrospectively. In the last visit 9 patients (15.7%) were in remission and 47 (84.2%) had active acromegaly. We considered hypertensive the patients with systolic BP > or = 140 and/or diastolic BP > or = 90 mmHg. Hypertension was classified in four stages:- mild, moderate, severe and very severe.

RESULTS

The prevalence of hypertension at the moment of diagnosis was 35%. The hypertensive patients had a mean age of 51.75 +/- 9.3 years and normotensive patients 41.65 +/- 11.6 years (p < 0.001). In females the prevalence of HT was 27.9% and in males it was 57% (p = NS). In hypertensive patients (n = 20), the mean BP was 159 +/- 15 (syst.)/97.2 +/- 9.8 (diast.), 16 patients (80%) had mild to moderate HT and the remainder had severe (n = 2) and very severe (n=1) HT. In the last visit, 22.2% of patients were cured and 46.8% of those with active acromegaly were hypertensive. None of the patients cured and initially normotensive developed HT; among those that were hypertensive (n = 3), 2 remained hypertensive and 1 became normotensive. Among patients with active acromegaly and initially normotensive, 7 developed HT 4.85 +/- 2.03 years later; of those hypertensive at diagnosis (n = 16), only one became normotensive. The last case was 27 years old. The patients that remained hypertensive had a mean age of 53.8 +/- 6.85 years (41-62 years).

CONCLUSIONS

The prevalence of hypertension at the moment of diagnosis was 35%, similar to the majority of studies published and higher than the general population. The hypertensive patients were significantly older the normotensive patients and most of them had mild to moderate HT. We observed an increase in the prevalence of HT over the years in the cases that maintained active acromegaly. In our series only one of the three patients cured became normotensive, therefore, we concluded that HT in acromegaly is frequently irreversible. The chances of normalization seems higher in younger patients and probably with a shorter duration of acromegaly.

[Pancreatic transplantation]

The AA. report on their very limited experience with whole pancreatic transplantation. For the moment this is the only experience in Portugal, the detailed report of the 3 cases may be of some help to other Portuguese groups interested in starting this therapeutical approach for insulin-dependent end-stage renal failure patients. The main comments focus on the third simultaneous pancreas-kidney transplantation, which failed for technical reasons, mainly related to less than good selection of both donor and recipient. In all the three cases the technique preferred was the duodenocystostomy. The 2 first cases are doing very well, free of insulin and with normal glucose metabolism, at 15 and 7 months after grafting. The AA. also make some considerations on the indications, complications and follow-up of patients with pancreas-kidney transplantation.

[Beneficial effects of added glicazide in patients with type II diabetes mellitus treated with insulin]

The aim of the study was to assess, in patients with non insulin dependent diabetes mellitus (NIDDM), either with previous failure to sulphonylureas or insulin treated since the disease started, if the combination of gliclazide to insulin therapy might induce a reduction of daily insulin requirement. 30 caucasian type II patients used to self-monitoring (11 female, 19 male, mean age 55.78 +/- 8.07) with residual pancreatic function (glucagon induced C-peptide release = 1.01 +/- 0.70 microgram/ml) entered the study. 8 were excluded for non compliance or for high antiinsulin antibodies levels and 4 are still under study. Each patients was given, for 3 months, 240 mg of gliclazide in addition to usual daily dose of insulin. Data presented as mean +/- s.e.m. were analysed with analysis of variance (p less than 0.05). Mean initial values of main parameters were as follows: glycaemia 192.7 +/- 33.1 mg/100 ml, insulinaemia 9.5 +/- 4.5 microUI/ml, daily insulin requirements 33.11 +/- 10.47 U/d, HbA1 C 7.5 +/- 1.7%. Total cholesterol 240.1 +/- 52.2 mg/10 ml, triglycerides 120.6 +/- 60.3 mg/100 ml. After 3 months treatment significant reduction in mean daily insulin requirements (20.78 +/- 16.15 U/d) was observed. In 13 patients (72.2%) while keeping good metabolic control (HbA1 C 7.46 +/- 1.63), insulin therapy was reduced (9 patients) or even stopped (4 patients). In the other 5, insulin was maintained or slightly increased. The increase in glucagon induced C-peptide release (1.41 +/- 0.99 micrograms/ml) did not reach significance, while glycaemia and insulinaemia were not changed (196.0 +/- 34.1 mg/100 ml, 11.02 +/- 5.05 microUI/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

[Pregnancy and endocrinopathy. Activity, pathology and results at the outpatient obstetrics-endocrinology clinics of the University of Coimbra Hospitals--January 1980 through December 1988]

The authors have elaborated a statistic survey about the pregnant women with endocrinopathies, that they have examined in the outpatient clinic from January of 1980 to December of 1988. Three hundred and twenty four women were examined in an amount of 2152 (two thousand one hundred and fifty two) observations. The incidence for 100 births was 0.54%. Maternal and fetal mobility and mortality were analysed in correlation with the maternal area of endocrinopathy (Diabetes Mellitus, Thyroid, Hypophysis and Adrenal Glands) and with the necessary therapeutic regimens. At last the A.A. made some considerations about the importance of a team approach in this area of medical care, and applied to the clinicians who work in primary care, to a better collaboration.