Organ doses, detriment and genetic risk from interventional vascular procedures in Málaga (Spain).

Nowadays, the radiological risk from simple X-ray procedures is well known. The purpose of this work has been to estimate the population risk from digital angiographic and interventional procedures and to compare it with the one from simple procedures in the same population. The population risk has been estimated according to the following quantities: genetically significant dose, somatic significant dose, collective effective dose, annual per caput effective dose and detriment. These have been estimated from dose area product and organ dose. Organ dose values were estimated with the Eff-Dose software. A population of 605410 people were included in the study. In 1996, 1312 patients were to digital interventional vascular procedures in Malaga, and 159 of them were selected in this research project to obtain the dose area product and organ dose. The results obtained for the quantities evaluated are: genetically significant dose, 4.1 microGy; somatic significant dose, 0.9 mSv; collective effective dose, 11.65 person-Sv: annual per caput effective dose, 0.02 mSv and detriment, 0.65 radiogenic cancers per year. These procedures supply a high radiation dose, so they should have a greater contribution to population dose and risk than simple examinations. However, our results indicate just the opposite.

Stochastic risk estimate for barium radiological examinations in Malaga (Spain).

The aim of this research work has been the estimation of the stochastic risk for five barium examinations. The sample was the population attending the Radiological Service of the 'Nuestra Señora de la Victoria' University Hospital, who had been treated with some barium examinations, set in five different groups: oesophagus tract, oesophagus-gastric-duodenal tract, intestinal tract, enteroclysis and double enema. To estimate the stochastic risk, it is necessary to know the organ dose. This can be calculated from the dose-area product which allows us to determine the effective dose using software. The dose-area product is the most suitable quantity to measure in these types of examination. We have evaluated the contribution that each procedure provides to the genetically significant dose, somatically significant dose, collective effective dose, annual effective dose 'per capita' and detriment, which are useful for assessing the population risk of cancer or hereditary effects after x-ray exposure. The contribution to the genetically significant dose is 6.7 microGy, to the somatically significant dose 8.82 mSv-yr, 16.07 person-Sv for the collective effective dose, 0.03 mSv for the 'per capita' annual effective dose and the annual aggregated detriment is 0.33.

Patient dose in radiologically guided interventional vascular procedures: conventional versus digital systems.

PURPOSE: To calculate the difference in the patient radiation dose in radiologically guided interventional vascular procedures between conventional and digital systems and to estimate the effective dose and the energy imparted with the digital system. MATERIALS AND METHODS: A total of 318 procedures (in 318 patients) in 15 different examination groups were analyzed. The dose-area product was determined by using a transmission chamber fitted to an x-ray-tube light-beam diaphragm; the effective dose was determined by using software. RESULTS: Urinary and biliary tract procedures showed small differences in the average dose-area product between conventional and digital systems. The dose-area products in the vascular procedures were higher with the digital than with the conventional system. The average effective dose and energy imparted were 0.88 mSv and 129 mJ, respectively, in the subcutaneous placement of a reservoir for analgesic administration and as much as 25.7 mSv and 829 mJ, respectively, in spermatic vein embolization. CONCLUSION: The dose-area product was higher with the digital system than with the conventional system in 13 of the 15 groups. To reduce the patient dose in vascular interventional radiology procedures, the training of personnel and the frequent use of conventional fluoroscopy and low-dose imaging are required.

DC potentials of the lateral wall of the scala media.

We recorded DC potential and resistance changes of the cochlear lateral wall in guinea pigs, using (3M KCl) electrolyte glass microelectrodes. The patterns found for slow penetration showed different potential and resistance characteristics at different segments of the lateral wall. In addition, our findings demonstrate that the monitoring of microelectrode tip resistance is a useful procedure for DC cochlear recordings.

Noradrenaline as a possible mediator of angiotensin II induced fluid transport in rat ileum in vitro.

In isolated segments of ileum excised from bilaterally adrenalectomized and nephrectomized rats, 10(-12) M angiotensin or 10(-3) M noradrenaline added to serosal medium stimulated both fluid transfer and NaCl transport. The alpha adrenergic antagonist phentolamine blocked the stimulation of fluid transfer induced by angiotensin. These results are consistent with the hypothesis that noradrenaline may mediate the increase of intestinal fluid absorption induced by angiotensin in the rat. In segments of isolated ileum from normal rats 10(-12) M angiotensin only stimulated fluid transfer under one of the two following conditions when 10(-3) M imipramine, a noradrenaline uptake blocker, was present in the serosal medium; or when the rats had been previously treated with L-Dopa, a precursor of noradrenaline biosynthesis. These results suggested that the necessity for bilateral adrenalectomy and nephrectomy might be associated to the necessity of increasing the tissue levels of noradrenaline. Direct measurement of noradrenaline tissue content confirmed this.

Apical membrane potentials and intracellular potassium and sodium activities in the gallbladder of the freshwater turtle Mauremys caspica.

Open-tip and liquid ion-exchanger microelectrodes were used to measure transapical membrane potential (Va), fractional voltage ratio (fa) and intracellular sodium and potassium activities (aiNa, aiK) in Mauremys caspica gallbladder under open circuit conditions. The average values (+/- SEM) for Va and fa were -32 +/- 3 and 0.20 +/- 0.03 mV respectively. aiNa and aiK were, respectively, 17 +/- 4 and 82 +/- 7 mM. These results suggest that the mechanisms of Na+ and K+ transport in this tissue are essentially similar to those observed in leaky epithelia in general.

Addition of cAMP to mucosal or serosal medium induces different actions on Necturus gallbladder.

Open tip and Cl(-)-selective microelectrodes were used to study the effects of cAMP on apical membrane potential (Va), fractional voltage ratio (fa) and intracellular chloride activity (aicl) in Necturus gallbladder under open-circuit conditions. In the presence of cAMP in the mucosal medium Va depolarized from -68 +/- 5 mV in control conditions to -56 +/- 5 mV and fa decreased from 0.56 +/- 0.15 in control conditions to 0.15 +/- 0.02. Concomitantly aicl fell from 15 +/- 2 mM to 8 +/- 3 mM, a value close to its electrochemical equilibrium activity. These results differ markedly from those obtained when cAMP was added to serosal medium and indicate that cAMP elicits different transport mechanisms whether it is added to the serosal medium or to the mucosal medium.

Sodium, potassium and chloride intracellular concentrations in the intestine of the freshwater turtle Mauremys caspica.

Sodium, potassium and chloride intracellular concentrations were measured. Sodium replacement from the bathing medium induced a significant decrease in chloride intracellular concentration. Conversely, chloride replacement from the bathing medium induced a significant decrease in sodium intracellular concentration. These results suggest the existence of a coupled NaCl transport system. The presence of 10(-3) M ouabain in the bathing medium increased Na+ intracellular concentration while decreasing that of K+. Cyanide (10(-3) M) produced a significant increase in Na+ intracellular concentration, whereas that of K+ was not affected by this agent.

Effect of bicarbonate and furosemide on chloride accumulation by the intestine of the freshwater turtle Mauremys caspica.

The influence of HCO3- on Cl- absorption by the intestine of the freshwater turtle Mauremys caspica has been studied. Na+, K+ and Cl- intracellular concentrations together with transepithelial potential difference were measured. In HCO3--free medium, transepithelial potential difference was serosal positive. A reversal in the sign of the transepithelial potential difference was observed in HCO3- medium. A subsequent addition of 10(-3) M furosemide to HCO3- medium blocked, at least partially, this response. However, neither the presence of HCO3- nor addition of 10(-3) M furosemide to HCO3+ medium had any effect on Na+, K+ or Cl- intracellular concentrations. These results are discussed in relation to the presence of a Cl-/HCO3- exchange process.

[Dosimetry in interstitial radiotherapy using neutrons]. / Dosimetría en radioterapia intersticial con neutrones.

A program to evaluate the dosimetry in complex implants of encapsulated sources of 252Cf has been written. The program can use different kind of sources (applicator tubes, short afterloading cells, afterloading cells, needles and seeds). Partial contribution to total dose of radiation due to neutrons and gamma rays are separately evaluated. The program can work in two modes: in one mode the dose in a given point is evaluated; in the other mode isodose contours are obtained. Neutron and gamma ray isodose contours are separately obtained. The program is written in BASIC.

Cyclic AMP and intracellular ionic activities in Necturus gallbladder.

Open-tip and liquid ion-exchanger microelectrodes were used to study the effects of cAMP (6mM, added to the serosal medium) on apical membrane potential (Em) and intracellular sodium, potassium, and chloride activities (alphaiNa, alphaiK, alphaiCl) in Necturus gallbladder under open-circuit conditions. Transepithelial potential difference (ETr) was also measured. In the presence of cAMP, alphaiCl fell from about 1.5 times its equilibrium value to a level that corresponded to electrochemical equilibrium across the apical and basolateral cell membranes. Under these conditions alphaiNa decreased and alphaiK increased, Em was unchanged and ETr increased from virtually zero to a small but significant serosal positive value. The cAMP-induced increase in alphaiK was abolished when Cl- -free incubation media were used. Addition of the Ca++-ionophore A23187 (0.5 microgram/ml) to the serosal medium had no effect on Em, ETr, or alphaiCl. When A23187 was added to the mucosal medium, Em and the basolateral membrane potential hyperpolarized by about 20 mV and an increase in the outwardly directed electrochemical driving force for Cl- was observed. These results indicate that cAMP inhibits coupled transapical Na-Cl entry into epithelial cells of Necturus gallbladder and suggest that this inhibition may not be mediated by an increase in intracellular Ca++ concentration.

Cytochalasin B does not stimulate sugar uptake into small intestine of necturus or chick.

3-O-Methylglucose accumulation by Necturus intestine was studied in the presence and absence of cytochalasin B. The effect of this agent on 3-O-methylglucose-induced changes in transepithelial potential difference was also investigated. Cytochalasin B (50 microM) blocked the rise in potential difference induced by 4 mM 3-O-methyglucose. 3-O-Methyglucose accumulation by Necturus intestine was measured; it was inhibited by cytochalasin B at concentrations of 50 and 100 microM. These results indicate that, in Necturus intestine, sodium-dependent sugar transport across the apical cell membrane is blocked by cytochalasin B.