Retrieval of droplet-size density distribution from multiple-field-of-view cross-polarized lidar signals: theory and experimental validation.

Multiple-field-of-view (MFOV) secondary-polarization lidar signals are used to calculate the particle-size density distribution (PSD) at the base of a cloud. At the cloud base, multiple scattering is weak and single backscattering is predominant by many orders of magnitude. Because secondary polarization is a direct measure of multiple scattering, it is therefore advantageous to use secondary polarization. A mathematical relation among the PSD, the lidar fields of view, the scattering angles, and the angular depolarization is derived to facilitate use of secondary polarization. The model is supported by experimental MFOV lidar measurements carried out in a controlled environment, and its limitations and restrictions are discussed.

Lidar-inversion technique based on total integrated backscatter calibrated curves.

The integrated backscatter signal from a smoke cloud contained in a chamber is studied as function of the measured concentration. An analysis based on the total backscattered signal leads to the determination of calibration curves specific to the material and to the lidar system. This procedure leads to a lidar inversion technique based on a calibrated total integrated backscatter curve. The limitation of the technique is discussed in terms of the maximum optical depth permitted for acceptable results.

Retrospective evaluation of the dose received by the ovary after radioactive iodine therapy for thyroid cancer.

In an earlier study, we evaluated the frequency of clinical manifestations of ovarian insufficiency after radioiodine therapy for thyroid cancer. We were thus led to consider the dose received by the ovary (DRO) during these treatments. In the literature, this dose is expressed as a function of the activity administered. However, in our study, the disorders were not correlated with the activity administered. Faced with this discrepancy, we have attempted to establish a dosimetric model using the parameters available for each patient. The results obtained show that besides the activity administered, which plays a role, morphological and kinetic factors specific to each individual have an importance that cannot be ignored when addressing this problem.

Temporary ovarian failure in thyroid cancer patients after thyroid remnant ablation with radioactive iodine.

We studied ovarian function retrospectively in 66 women who had regular menstrual cycles before undergoing complete thyroidectomy for differentiated thyroid cancer and subsequent thyroid remnant ablation with 131I. Eighteen women developed temporary amenorrhea accompanied by increased serum gonadotropin concentrations during the first year after 131I therapy. No correlation was found between the radioactive iodine dose absorbed, thyroid uptake before treatment, oral contraceptive use, or thyroid autoimmunity. Only age was a determining factor, with the older women being the most affected. We conclude that radioiodine ablation therapy is followed by transient ovarian failure, especially in older women.

[Thyroid function and trisomy 21. TSH increase and rT3 deficiency]. / Fonction thyroïdienne et trisomie 21 excès de TSH et déficit en rT3.

An excess of thyrotropin (TSH) with normal levels of tetraiodothyronine (T4) and of 3,5,3'-triiodothyronine (T3) was confirmed in the serum of 78 trisomy 21 children. A severe deficiency of 3,3',5'-triiodo-thyronine (rT3 or reverse T3) was observed and the decrease of the rT3/TSH ratio was highly significant. These new facts suggest that the rT3 deficiency plays a peculiar role in trisomy 21 (maybe through the regulation of one or few steps of monocarbons' metabolism). A systematic control of thyroid function (including the patient's rT3 level) is mandatory for the follow-up of every trisomy 21 patient.

Thyroglobulin secretion by cultured human thyroid cells from cold nodules.

An elevated serum thyroglobulin level has been demonstrated in patients with cold nodules, without determination of the exact cause. In this preliminary study, we examined thyroglobulin production in vitro by cells from cold nodules and compared it to that of normal cells taken from the contralateral lobe of the same patient. Cells were cultured in monolayer and in collagen gel. Differences were observed between normal and pathological cells depending upon the culture model. We have attempted to interpret these differences which could result from anomalies in the pathological cells at the level of the apical membrane.

[New method of estimating iodine overload in the urine from a simple urination]. / Une nouvelle méthode d'appréciation des surcharges iodées sur les urines d'une simple miction.

Iodine research holds an increasing place in thyroid pathology, either to cover a radioisotopic investigation with paradoxal results or to find an iatrogenic cause to an unexplained hypo- or hyperthyroidism in new born children as well as in adults. To determine iodine overloads we may need a urinary iodine estimation, in addition to blood iodine determination (quickly eliminated products) or instead of it (difficult blood taking: new born children, etc.). Classically, the 24 hours urinary iodine estimation (total urinary iodine) covers this need but, in practice, as we generally deal with ambulatory patients, the risks linked to the obtention of a perfect 24 hours urine collecting make us abandon it. This article presents an original and simple way of getting round this difficulty: it demonstrates that an excellent iodine overload estimation can be obtained by measuring simultaneously from a simple miction: on one hand iodine concentration, on the other hand the urinary creatinine.

[Thyroid biological evaluation: critical study]. / Le bilan biologique thyroïdien: étude critique.

Laboratory tests to assess thyroid gland function have changed considerably over the past few years, with the development of techniques allowing for the direct routine determination of unbound thyroid hormones (tri and tetra-iodothyronine), the "ultra-sensitive" assay of serum concentrations of TSH (thyroid-stimulating hormone) and finally, the radioimmunological assay of anti TSH-receptor antibodies. In our study, which excluded patients having an excess of iodine or who had serious disease of an organ other than the thyroid, we assessed the impact of these parameters respectively on various disease categories. An innovation has been made in that anti TSH-receptor antibody assay is now possible in everyday practice while up to the present this was only possible in the hospital setting and with a limited number of cases: this titer is important as a classification parameter in diagnosing Grave's disease and has prognostic importance to monitor treatment of patients suffering from this disorder. The "ultrasensitive" version of measuring thyrotropic hormone requires a new strategy: TSH assessment becomes the first-line diagnosis test to evaluate thyroid function because it differentiates from control subjects, as well as patients with hyper ou hypothyroidism who are not receiving therapy. In other cases, dosing of the free hormones T3 and T4 remains a vital supplementary test.

[Thyroid function of burned patients: effect of iodine therapy]. / Fonction thyroïdienne du brûlé: incidence de la thérapeutique iodée.

Thyroid function was studied in 3 groups of adults (group I = 13 burned patients treated with non iodinated antiseptic, group II = 15 burned patients treated with polyvidone iodine, group III = 50 control subjects) in order to examine: the thyroid hormone status in burned patients, the possible incidence of plasma iodine overload on these endocrine parameters. Burned skin area and thyroid function were measured before treatment, then weekly for 3 weeks. Before treatment a decrease in plasma T4 and T3 with an increase in reverse T3 (rT3) and a decrease in plasma thyroxin binding globulin (TBG) were observed in burned patients. Free T4 index (T4/TBG) was normal, but T3 resin uptake (T3RU) was elevated. During treatment, plasma iodine increase sharply from 6.4 +/- 0.4 to 20.7 +/- 4.7 micrograms/100 ml (p less than 0.02) in group II. Endocrine parameters (not different between group I and II) progressively returned to normal, except for T3RU which remained elevated until the third week. rT3, T4 and T3RU correlated (p less than 0.001) with burned skin area. To conclude, the reversible particularities of thyroid function in burned patients are positively correlated with burned area. The thyroid function does not seen to be modified by plasma iodine overload.