Radon progeny unattached fraction in an atmosphere far from radioactive equilibrium

It is often assumed that the unattached fraction of the exposure to suspended radon progeny activity can be predicted from particle concentration measurements. While this may be true in many circumstances, there are important exceptions to this rule. In particular, in an atmosphere far from radioactive equilibrium, such as a working area in a mine close to a source of radon and supplied with fresh air, the unattached fraction can be a factor of ten or more greater than indicated by a simple particle concentration measurement. Recent measurements made in a diesel powered uranium mine are presented to illustrate this effect.     

Hyponatremia in neurosurgical patients

Hyponatremia played an essential role in this case, determining the rapid transition from consciousness to a state of coma in female patient who had just come through the critical phase of intensive care. This circumstance underlines the importance of a correct water balance in patients undergoing neurosurgery, as well as a knowledge of the inappropriate antidiuretic hormone secretion (SIADH) syndrome responsible, either alone or in association, for the genesis of severe hyponatremia. In the differential diagnosis of hyponatremia, it is important to recall the role of an often mistaken syndrome (cerebral salt wasting syndrome) characterized by the secretion of a natriuretic factor that has still not been clearly identified.     

Macular edema induced by phacoemulsification

Purpose: To characterise the association between lens phacoemulsification and the development of macular edema. Methods: We studied 15 patients who underwent lens phacoemulsification in our clinic between January and April 1998 performed by the same surgeon. Ultrasound power and cumulative time was noted. Follow-up was performed at 1 day, 1 week, 1, 3 and 6 months after operation. On each visit corneal thickness, best corrected visual acuity, biomicroscopy and fluorescein angiography were performed. Patients with systemic diseases and/or retinal diseases were not included. Results: Visual acuity was inversely related to the amount of energy delivered during phacoemulsification. In patients who had received more than 1 Joule of energy, fluorescein angiography revealed a higher incidence of blood retinal barrier breakdown. Corneal thickness was not correlated with the ultrasound energy used. Conclusions: Excessive use of power during phacoemulsification may hamper the postoperative evolution of cataract surgery. This revised version was published online in July 2006 with corrections to the Cover Date.     

Clinical Measurement of Testicular Volume in Adolescents: Comparison of the Reliability of 5 Methods

Purpose

Measurement of the testis is a more readily available method of estimating spermatogenesis. Doubt remains about the best instrument for measuring testicular volume. Lack of bias or accuracy of instruments has received too much emphasis in some studies, while to our knowledge no one has yet appropriately compared reliability statistically. We propose a simple new method for measuring testicular size based on visual comparison with graphic models, and describe the reliability and bias of this and 4 traditional methods.

Materials and Methods

Measurements of 42 adolescent testes were made in a certain sequence: graphic method, dimensional measurement, Prader orchidometer, ring orchidometer and ultrasound with ultrasound assumed to be the standard. Statistical analysis was based on the linear structural model.

Results

Statistical tests indicated that all 5 methods are equally reliable (R greater than 0.9). Although they are not equally accurate, actual testicular size can be calculated using each of these 5 methods and the equations of the linear structural model.

Conclusions

The new graphic method proposed in this study is as reliable as other well-known methods for measuring testicular size. Actual testicular volume can be estimated without bias and with equal reliability from any of the 5 methods using the equations of the linear structural model. This statistical approach is more relevant than the sole comparison of lack of bias or accuracy, which has been the main concern of previous studies.     

Influence of acid-base alterations on myocardial sensitivity to catecholamines

Summary The influence of respiratory and metabolic acid-base alterations on the myocardial sensitivity to catecholamines was studied in the isolated rat atria. The ability of noradrenaline for increasing the atrial rate was enhanced during alkalosis and conversely, it was decreased by acidosis. These changes in sensitivity shifted the concentration-effect curve for noradrenaline to the right by about 0.5 log unit when the pH was lowered from 7.60 to 7.00. No changes in the maximum attainable response were detected. Essentially the same shifts of the concentration-effect curves were obtained with changes in pH brought about by altering the pCO₂ or at constant pCO₂. The decrease in the pH produced a similar shift to the right of the concentration-effect curve for isoprenaline, after the extraneuronal uptake inhibition by hydrocortisone and also in atria tissue with low content of endogenous noradrenaline (reserpine-pretreated and newborn rats). The ability of isoprenaline for increasing cyclic AMP levels in atrial tissue was also enhanced by alkalosis and decreased by acidosis. However, the shift to the right of the concentration-effect curve for cyclic AMP induced by the decrease in the pH was greater than the shift detected in the chronotropic-effect curve. In addition a decrease in the maximum increment of cyclic AMP was detected under acidosis, in spite of equal maximal chronotropic response.Our results support the hypothesis that the alterations in the sensitivity to catecholamines induced by the changes in pH are not due to a release of endogenous noradrenaline nor to alterations of the mechanisms which remove catecholamines from the biophase. The fact that cyclic AMP response to catecholamines was also reduced by acidosis strongly suggests that the mechanism(s) involved is located in the earlier steps of the events leading to the chronotropic effect of the -agonists.     

Chlorpyrifos-induced delayed polyneuropathy

Chlorpyrifos [0,0-diethyl 0-(3,5,6-trichloro-pyridyl) phosphorothioate] caused delayed polyneuropathy in man. Contrary to previous studies, we report here that it also causes delayed polyneuropathy in the hen, the animal model for this toxicity. The minimal neuropathic dose was 60–90 mg/kg p.o., corresponding to 4–6 times the estimated LD₅₀. Consequently, pralidoxime (2-PAM) in conjunction with atropine was necessary to reverse acetylcholinesterase (AChE) inhibition and cholinergic toxicity in hens given high enough doses of chlorpyrifos to cause neuropathy. Chlorpyrifos was slowly absorbed after single oral doses and the threshold of inhibition (>70%) of neuropathy target esterase (NTE), the putative target for delayed neuropathy, was reached within 5–6 days. High AChE inhibition (>90%), however, was measured within hours after dosing because of the higher potency of chlorpyrifos to inhibit this enzyme. In vitro studies showed that chlorpyrifos-oxon, the active metabolite of chlorpyrifos, was 10–20 times more active against AChE than against NTE, confirming the clinical observation. No differences were seen between human and hen enzymes in this respect. Hen and human brain homogenates contain A-esterases which hydrolysed chlorpyrifos to about the same extent in both species. In conclusion, chlorpyrifos causes delayed polyneuropathy in the hen, as was reported in man. The reasons for previous negative data in the hen are probably due to the relatively lower doses which were used. Judging from in vitro studies with hen and human enzymes, there are no differences in the two species as far as their relative sensitivity to delayed polyneuropathy. It is likely that delayed polyneuropathy would develop in both species only after severe cholinergic toxicity requiring aggressive antidotal treatment.Part of this work was presented at the 25th Annual Meeting of the Society of Toxicology held in New Orleans, LA, USA, March 1986, at the International Symposium on Biochemical and Cellular Indices of Toxicity in Occupational and Environmental Medicine held in Milan, Italy, June 1986, and at the 9th Meeting of the Peripheral Nerve Study Group, Praglia (PD), Italy, August – September, 1989     

Cardiac function in congenital hypothyroidism: Impairment and response to L-T4 therapy

Summary Electrocardiograms (heart rate, QRS voltage, QRS axis in the frontal plane, Q-Tc interval), echocardiograms [left ventricular fractional shortening (LVFS); preejection period (PEP); PEP/left ventricular ejection time (PEP/LVET) ratio; end-diastolic left ventricular free wall and interventricular septum thickness; presence of pericardial effusion], and thyrotropin (TSH), thyroxine (T₄), and triiodothyronine (T₃) serum levels were evaluated before and 1 week, 1 and 2 months after the start ofl-thyroxine (L-T₄) therapy in 11 infants with congenital hypothyroidism (CH), aged 16–59 days when first seen.Before the start of therapy, infants with CH had significantly lower QRS complexes and LVFS and significantly higher values for Q-Tc, PEP, and PEP/LVET than normal infants of the same age. The QTc interval, PEP and PEP/LVET ratio of infants with CH were significantly greater before than 1 week after L-T₄ therapy, and LVFS was significantly lower before than 1 month after L-T₄ therapy. Four of the infants with CH had small pericardial effusions, which disappeared within the first week of therapy.QRS axis in the frontal plane, Q-Tc interval, and PEP were negatively correlated with logT₄ and logT₃ serum levels. PEP/LVET ratios were negatively correlated with logT₄ serum values. The QRS voltage values were positively correlated with logT₄ and logT₃ serum values. The frontal-plane QRS axis, Q-Tc interval, and PEP/LVET ratio were positively correlated with logTSH serum levels. The QRS voltages were negatively correlated with TSH serum levels.Our data show that before therapy infants with CH have the same functional, but not morphological, abnormalities as older hypothyroid ones and that one third of them have small pericardial effusions. L-T₄ therapy rapidly reverses these changes.     

Ipriflavone inhibits osteoclast differentiation in parathyroid transplanted parietal bone of rats

Summary Ipriflavone, a synthetic isoflavone-derived flavonoid, was shown to have inhibitory effect on bone resorption. In order to study its mechanism of action directly on bone, 46 female Wistar rats were divided into six groups and medicated orally for 25 days as follows: groups 1 and 2 were given 1% carboxymethylcellulose solution (vehicle), groups 3, 4, 5, and 6 were administered ipriflavone at doses of 0.178, 0.356, 0.712, and 1.424 mmol/kg/day (suspended in vehicle), respectively. On the 22nd day, parathyroid glands, taken from donor rats, were transplanted in contact with the outer surface of the periosteum of both the right and the left parietal bones of rats from groups 2, 3, 4, 5, and 6. The group 1 rats underwent sham operation. Bone histomorphometry, performed on the ectocranial periosteum of parietal bones, showed that absolute erosion boundary, absolute eroded area, absolute erosion depth, number of tartrate-resistant acid phosphatase (TRAP)-positive polinucleated osteoclasts, and number of TRAP-positive mononucleated cells decreased in ipriflavone-treated rats compared with group 2 rats. The reduction was roughly proportional to the increase of drug dosage and reached statistical significance in rats of groups 5 and 6. The same parameters were extremely low in group 1 rats. Mineral apposition rate did not differ in any of the groups. Significant increase of serum calcium and significant decrease of serum phosphate were found in group 2 rats compared with group 1 rats, whereas no differences from controls were detected in ipriflavone-treated animals.The results demonstrate that ipriflavone has a direct inhibitory effect upon bone resorption, probably by reducing recruitment or differentiation of osteoclasts, rather than by inhibiting the resorption activity of differentiated osteoclasts. Ipriflavone also seems to exert a protective action against parathyroid hormone (PTH) diffusion from the site of parathyroid gland transplantation.     

Lomest psychiatric case register: Old and new long-stay patients

Summary Data derived from a psychiatric case-register are presented on the attrition of the cohort of theold long-stay in-patients, and the accumulation of thenew long-stay cases in Lomest, a town in northern Italy, from 1975 to 1980. The characteristics of high user groups of out-patients attending the non-residential services are also described. The analysis seeks to provide some information on who has been left behind by the massive deinstitutionalization programme that has been carried out in Italy since 1970.     

Nephrotoxic and cytoproliferative effects of streptozotocin: report of a patient with multiple hormone-secreting islet cell carcinoma.

The nephrotoxic and cytoproliferative side effects observed in a patient with Streptozotocin-treated, multiple hormone-secreting, pancreatic islet cell carcinoma are described. Streptozotocin induced prolonged partial remission of the patient's multiendocrine syndrome but resulted in progressive azotemia, which was controlled by temporary hemodialysis. A renal biopsy, the first to be reported in detail in such a condition, demonstrated a tubulo-interstitial nephritis and a glomerular alteration consisting of cellular nodules. At autopsy there were numerous bilateral renal cortical spindle cell "tumors" and cellular aggregates in glomeruli. These findings suggest that the tumorigenic effects of Streptozotocin demonstrated in animals may also occur in man.