Abstract PO009: Epigenetic silencing by SETDB1 represses tumor-cell intrinsic immunogenicity

Epigenetic alterations are defining features of many tumor types and have recently been implicated in tumor immunity. However, the epigenetic mechanisms that mediate immune sensitivity or resistance in cancer cells are poorly characterized. To systematically identify epigenetic regulators of immune evasion in cancer, we performed in vivo loss of function CRISPR screens against 936 chromatin regulator genes in syngeneic murine tumor models treated with immune checkpoint blockade. These screens identified SETDB1, an H3K9-methyltransferase, and associated members of the HUSH and KAP1 complexes as intrinsic mediators of immune evasion in cancer cells. We also found that amplification of SETDB1 (1q21) in certain human tumors is associated with immune exclusion and resistance to immune checkpoint blockade. Mechanistically, we find that SETDB1 targets broad domains, hundreds of kilobases in size, that are predominantly located within the open genome compartment “A” (i.e., euchromatin). These SETDB1 domains show strong enrichment for transposable elements (TEs) of the LTR family, and gene loci that arose through segmental duplication events, a key driver of mammalian genome evolution. Setdb1 KO derepresses latent regulatory elements at TEs within these regions and leads to the transcriptional up-regulation of nearby immune genes, including canonical stimulatory ligands of the NKG2D receptor. SETDB1 loss also triggers the activation of hundreds of TEs with the potential to encode retroviral proteins (Gag, Pol, Env), and promotes immune responses dependent on CD8+ T cells and tumor expression of MHC Class I. Our study establishes SETDB1 as an epigenetic checkpoint that represses intrinsic immunogenicity in cancer cells, and thus represents a novel target to enhance the efficacy and scope of immunotherapy.

Citation Format: Jingyi Wu, Arvin Iracheta-Vellve, James Patti, Jeffrey Hsu, Thomas Davis, Deborah Dele-Oni, Peter Du, Jeffrey Ishizuka, Sarah Kim, Susan Klaeger, Nelson Knudsen, Brian Miller, Tung Nguyen, Emily Robitschek, Emily Schneider, Margaret Zimmer, Jacob Jaffe, John Doench, W. Nicholas Haining, Kathleen Yates, Robert Manguso, Bradley Bernstein, Gabriel K. Griffin. Epigenetic silencing by SETDB1 represses tumor-cell intrinsic immunogenicity [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO009.

Liposarcoma of the Thyroid Gland

The presumed first case of primary liposarcoma of the thyroid gland is presented, and the possible origin of this rare tumor from either mature fat cells or primitive mesenchymal cells is discussed.

Automatic data collection for cardiopulmonary bypass

An open software system for automatic data collection during cardiopulmonary bypass is presented. The software is run on a microprocessor with permanent memory, a general purpose interface board capable of analogue-to-digital conversion and five serial communication ports for data collection.

Analogue data signals for blood flow, gas flow, patient temperatures and pressures are automatically recorded and referenced to real time. Continuous inline blood gas and temperature parameters are passed to the microprocessor for storage in a database. Results from a blood analyser and an electrolyte analyser, placed in the next room, are automatically passed to the computer and presented on the screen.

This system provides the perfusionist with automatic preoperative calculations of all parameters necessary for setting up the perfusion. During bypass, data are automatically collected, presented for evaluation and used in calculated transformations. A maximum of 36 real time curves are traced and stored as trend curves. In critical situations they may also be stored as real time curves. These curves can be recalled or plotted for further analysis. At the end of bypass a perfusion report is printed out.

The records of the patients are permanently stored on disk and the files can be transferred to other software systems for further statistical analysis.

Abstract 178: Angiogenesis is Triggered by Nutrient Deprivation via Gcn2/atf4-dependent Regulation of Vegf and H2s Production

Objective: Angiogenesis is crucial to maintain tissue homeostasis under nutrient and oxygen deprivation (ischemia). Although considerable evidence supports that angiogenesis is regulated by hypoxia-HIF1α induction of vascular endothelial growth factor (VEGF), the role of nutrient deprivation in angiogenesis is poorly defined.

Approach and Results: We report that nutrient deprivation in the form of dietary sulfur amino acid restriction (Methionine/cysteine Restriction; MR) promotes VEGF expression and functional growth of new capillaries in skeletal muscle of mice (Fig.1 A, B). This occurred independently of hypoxia or HIF1α, but instead required the amino acid-sensing eIF2α kinase GCN2 and the transcription factor ATF4 (Fig. 1C). In addition to increased VEGF, nutrient deprivation boosted production of the pro-angiogenic gas hydrogen sulfide (H 2 S) via increased GCN2/ATF4-dependent expression of the H 2 S-generating enzyme cystathionine-gamma-lyase (CGL). The genetic requirement for CGL in angiogenesis triggered by nutrient deprivation, exercise or local VEGF overexpression, as well as the ability of local CGL overexpression to promote angiogenesis in vivo, revealed the critical importance of CGL-derived H 2 S in angiogenesis (Fig. 1D). Finally, plasma H 2 S was reduced in patients with vascular disease (versus non-diseased age-matched controls), and correlated with 2-year survival following vascular surgery (Fig.1 E, F).

Conclusions: These data reveal a nutrient-sensing pathway targetable by diet as a previously unrecognized central regulator of VEGF expression and angiogenesis independent of canonical hypoxic signaling. This discovery points to novel dietary interventions and GCN2/ATF4/CGL/H 2 S-based strategies to manipulate angiogenesis.

Figure 1

Low socio-economic status and familial occurrence of goitre are associated with a high prevalence of goitre

The occurrence of goitre is dependent on genetic and environmental factors, but the associations with socio-economic and life-style factors have only been examined briefly. A cohort of 4649 participants from the general population was examined with questionnaires, thyroid ultrasonography, clinical examination and blood tests. Data were analysed in linear models and logistic regression analysis. Thyroid volume and serum thyroglobulin were closely associated with educational level with higher values in the group with the lowest levels of education (p < 0.001). The same pattern applied to thyroid multinodularity at ultrasonography (p = 0.002) and palpable goitre (p = 0.01). Physical activity in leisure time was negatively associated with thyroid enlargement (p = 0.02) and serum thyroglobulin (p < 0.001). These associations diminished markedly if adjustment was made for smoking habits, alcohol consumption and iodine intake. Familial occurrence of goitre was associated with goitre prevalence (Odds Ratio 2.5, 95% CI: 1.6-3.9), but did not confound the socio-economic associations. In conclusion, social imbalances in the occurrence of goitre were identified. These imbalances could in part be explained by differences in smoking habits and iodine intake.

High occurrence of thyroid multinodularity and low occurrence of subclinical hypothyroidism among tobacco smokers in a large population study

Tobacco smoking increases the risk of goitre and Graves' disease, but the association with thyroid nodularity and hypothyroidism has not been settled. We investigated 4649 subjects from the general population with questionnaires, thyroid ultrasonography and blood tests. The results were analysed in multivariate regression models. Tobacco smoking was associated with an increased prevalence of thyroid multinodularity (odds ratio (OR) 1.9; 95% confidence interval (CI) 1.4-2.5), but not with increased prevalence of solitary thyroid nodules. The tendency was for a stronger association in the area with the most pronounced iodine deficiency (P for interaction=0.08). Lower levels of serum TSH were found among tobacco smokers (P<0.001), but this association disappeared when adjustment was made for thyroid nodularity and thyroid Volume. The prevalence of elevated TSH levels was markedly reduced among smokers (OR 0.47; 95% CI 0.33-0.67). No association was found between smoking and hyperthyroidism. The observed associations seem to be explainable by the blocking of iodine uptake and organification in the thyroid by thiocyanate, a degradation product of cyanide in tobacco smoke.

TSH-receptor antibody measurement for differentiation of hyperthyroidism into Graves' disease and multinodular toxic goitre: a comparison of two competitive binding assays

OBJECTIVES

Graves' disease is characterized by stimulating autoantibodies to the TSH-receptor (TRAb). The aim of this study was to compare the performance of a new TRAb assay based on competitive binding to recombinant human TSH-receptors (H-TRAb) with an assay employing purified porcine TSH-receptors (P-TRAb). Furthermore, to evaluate the applicability of the H-TRAb assay to discriminate between patients with hyperthyroidism due to Graves' disease (GD) and multinodular toxic goitre (MNTG).

DESIGN AND MEASUREMENTS

H-TRAb and P-TRAb were measured in patients with newly diagnosed hyperthyroidism due to GD (n = 106) and MNTG (n = 94). For comparison, TRAb was measured in patients with primary autoimmune hypothyroidism, euthyroid subjects with an enlarged thyroid gland by ultrasound, and healthy controls (n = 100 for each group). Patients were consecutively included from a population survey.

RESULTS

If the cut-off values recommended by the manufacturer for TSH-receptor antibody positivity were used for evaluation, the sensitivity of the H-TRAb assay vs. the P-TRAb assay in diagnosing GD was: 95.3/67.9% (P < 0.001). Specificity was (H/P-TRAb): 99/99%. The sensitivity of P-TRAb was increased if the upper 97.5% limit of measurements in controls was used as cut-off (H-TRAb vs. P-TRAb: 95.3/80.2%, P < 0.001). Specificity (H/P-TRAb): 98/98%. The difference between assay performance may partly be due to a better technical performance of the H-TRAb assay with more reliable results in the low range of measurements. However, even in GD patients with clearly measurable TRAb, 25% had a P-TRAb < 50% of the value expected from the H-TRAb measurement. This suggests that a subgroup of patients produce TRAb with a higher affinity for the human than the porcine TSH receptor. A relatively high proportion of patients with MNTG were TRAb positive (H-TRAb/P-TRAb: 17/9%). Characteristics of H-TRAb positive and negative MNTG patients were compared. There was no difference between size of thyroid gland and number of nodules by ultrasonography. H-TRAb positive patients had significantly higher serum T4 and T3 and a greater number were TPO-Ab positive.

CONCLUSIONS

H-TRAb diagnosed Graves' disease with a high sensitivity and specificity than P-TRAb. The high occurrence of TRAb in multinodular toxic goitre might in part reflect an overlap between Graves' disease and multinodular toxic goitre in some patients.

Evaluation of a semi-quantitative food frequency questionnaire to estimate iodine intake

OBJECTIVE

To evaluate a food frequency questionnaire (FFQ) used to assess the dietary intake of iodine.

DESIGN

The iodine intake determined by the FFQ was compared with 4-day dietary records and with iodine excretion in 24 h urine samples in a subgroup of participants in a cross-sectional study of iodine intake and thyroid diseases in Denmark. Furthermore, the intake of fish determined from the FFQ was compared with the intake of fish from a simple record kept for 3 months.

SUBJECTS

Women aged 25-30 y and 60-65 y.

RESULTS

Median iodine intake was similar when determined from the FFQ and from dietary records and the correlation between these measures was 0.52 (P < 0.001). Iodine intake was higher than iodine excretion (P < 0.001). The cross-check questions in the FFQ (for example the question 'How often did you get any kind of fish?') underestimated the intake. In contrast, the intake of a specific fish tended to be overestimated by the FFQ when compared with the 3 month record of fish intake.

CONCLUSION

The FFQ can be used to classify subjects into low and high iodine intake groups, but the level of iodine tends to be overestimated.

Serum Tg--a sensitive marker of thyroid abnormalities and iodine deficiency in epidemiological studies

Serum Tg is widely used in the control of thyroid cancer but also in the diagnosis of certain other thyroid diseases. Serum Tg may be useful in the characterization of the iodine status of a population, but little is known about determinants of serum Tg levels. We examined a random selection of 4,649 subjects from 2 regions in Denmark with different iodine status. Thyroid volume and structure were determined with ultrasonography, and thyroid function tests and Tg analysis were performed. The factor with the closest association with serum Tg levels was thyroid volume at ultrasonography (P < 0.001). Also thyroid nodularity (P < 0.001) and iodine excretion (P < 0.001) had close associations to serum Tg, even after adjusting for the influence of the other parameters. Thyroid dysfunction had a less pronounced but still highly significant association with serum Tg (P < 0.001), but no relation was found to serum TSH in general. The association with age seemed to rely on differences in the prevalence of thyroid abnormalities, and men had lower Tg levels than women of the same age. There was a marked difference in serum Tg between the two regions with slightly different iodine excretion also after adjusting for the other factors. In conclusion, serum Tg reflects thyroid abnormalities and thyroid function and is a sensitive marker of iodine deficiency in a population.

Alcohol consumption is associated with reduced prevalence of goitre and solitary thyroid nodules

OBJECTIVE

Goitre prevalence is dependent on iodine intake and smoking habits, but further risk factors have only been examined briefly. We examined the association between alcohol consumption and the prevalence of thyroid enlargement and nodularity.

DESIGN

Cross-sectional population study with ultrasonography of the thyroid gland and assessment of alcohol intake and smoking habits from questionnaires.

SUBJECTS

Four thousand six-hundred and forty-nine men and women aged 18-65 years, randomly selected from the Danish Civil Registration System.

MEASUREMENTS

Thyroid volume and prevalence of thyroid enlargement, multiple nodules or a solitary nodule in the thyroid.

RESULTS

Abstainers and participants with a low alcohol consumption (< 7 drinks/week) had the same prevalence of thyroid enlargement and nodularity, but participants with moderate (8-28 drinks/week for women, 8-42 for men) or high (> 28/42 drinks/week) alcohol consumption had much lower prevalence of thyroid abnormalities. Possible confounding by sex, age, iodine status and smoking was considered in all models. Odds ratios compared to abstainers for thyroid enlargement were 0.74 [95% confidence interval (CI) 0.57-0.96] for moderate- and 0.44 (95% CI 0.22-0.88) for high alcohol consumption. Odds ratios compared to abstainers for a solitary nodule were 0.64 (95% CI 0.42-0.96) for moderate- and 0.41 (95% CI 0.12-1.37) for high alcohol consumption. Mean thyroid volume was 13.5 ml among abstainers compared to 10.9 ml among participants with high alcohol consumption (P < 0.001). Both wine- and beer consumption were associated to lower prevalence of thyroid abnormalities.

CONCLUSIONS

Increasing levels of alcohol consumption were associated to lower prevalence of thyroid enlargement and to lower prevalence of a solitary nodule in the thyroid, and indications of a causal relationship were found.

Environmental iodine intake affects the type of nonmalignant thyroid disease

The relationship between the iodine intake level of a population and the occurrence of thyroid diseases is U-shaped with an increase in risk from both low and high iodine intakes. Developmental brain disorders and endemic goiter caused by severe iodine deficiency may seriously deteriorate overall health status and economic performance of a population. Severe iodine deficiency with a median 24-hour urinary iodine excretion of the population below 25 microg needs immediate attention and correction. Less severe iodine deficiency with median urinary iodine excretion below 120 microg per 24 hours is associated with multinodular autonomous growth and function of the thyroid gland leading to goiter and hyperthyroidism in middle aged and elderly subjects. The lower the iodine intake, the earlier and more prominent are the abnormalities. At the other end of the spectrum, severely excessive iodine intake starting at median urinary iodine excretion levels around 800 microg per 24 hours is associated with a higher prevalence of thyroid hypofunction and goiter in children. A number of studies indicate that moderate and mild iodine excess (median urinary iodine >220 microg per 24 hours) are associated with a more frequent occurrence of hypothyroidism, especially in elderly subjects. The exact mechanism leading to this has not been clarified, and more studies are needed to define the limits of excessive iodine intake precisely. Due to the frequent occurrence of thyroid disorders, proper monitoring and control of the population iodine intake level is a cost-effective alternative to diagnosing, therapy and control of the many individual cases of thyroid diseases that might have been prevented.

Folate intake, lifestyle factors, and homocysteine concentrations in younger and older women

BACKGROUND

An elevated total homocysteine (tHcy) concentration is considered to be an independent risk factor for cardiovascular diseases and has also been associated with an increased risk of neural tube defects.

OBJECTIVE

The objective of this study was to investigate folate intake, folate status, and the association between folate intake, other dietary and lifestyle factors, and tHcy concentrations in young and older women.

DESIGN

tHcy concentrations were measured in 290 young women aged 25-30 y and in 288 older women aged 60-65 y. All participants completed questionnaires about factors including lifestyle, health, and use of vitamin supplements. Red blood cell folate was measured in 204 of the participants. A subgroup of 258 participants completed dietary records.

RESULTS

Median tHcy was 7.6 micromol/L (range: 6.5-8.9) in the younger women and 9.4 micromol/L (7.7-11.1) in the older women. Folate intake from diet was 283 (224-348) and 268 (210-326) microg/d, respectively, in the 2 age groups. Folic acid intake from supplements (P: < 0.001 for the younger women and P: = 0.026 for the older women) and total folate intake (P: = 0.024 and P: = 0.079) were inversely associated with log tHcy in multiple linear regression analyses. Smoking status, coffee consumption, systolic blood pressure, and body mass index were positively associated and estrogen replacement therapy and tea consumption were inversely associated with log tHcy in some of the models.

CONCLUSIONS

According to the criteria used, between 1% and 36% of the women had suboptimal folate intake. Folic acid is a strong predictor of tHcy concentration; however, several dietary and other lifestyle factors seem to be important as well.

Thyroid disorders in mild iodine deficiency

Comparative epidemiologic studies in areas with low and high iodine intake and controlled studies of iodine supplementation have demonstrated that the major consequence of mild-to-moderate iodine deficiency for the health of the population is an extraordinarily high occurrence of hyperthyroidism in elderly subjects, especially women, with risk of cardiac arrhythmias, osteoporosis, and muscle wasting. The hyperthyroidism is caused by autonomous nodular growth and function of the thyroid gland and it is accompanied by a high frequency of goiter. Pregnant women and small children are not immediately endangered but the consequences of severe iodine deficiency for brain development are grave and a considerable safety margin is advisable. Moreover, a shift toward less malignant types of thyroid cancer and a lower radiation dose to the thyroid in case of nuclear fallout support that mild-to-moderate iodine deficiency should be corrected. However, there is evidence that a high iodine intake may be associated with more autoimmune hypothyroidism, and that Graves' disease may manifest at a younger age and be more difficult to treat. Hence, the iodine intake should be brought to a level at which iodine deficiency disorders are avoided but not higher. Iodine supplementation programs should aim at relatively uniform iodine intake, avoiding deficient or excessive iodine intake in subpopulations. To adopt such a strategy, surveillance programs are needed.

Comparative study of thyroid function and types of thyroid dysfunction in two areas in Denmark with slightly different iodine status

OBJECTIVE

The pattern of thyroid dysfunction seems to depend on the iodine status of the population. Prevalence of thyroid dysfunction could be a parameter to consider when evaluating iodine deficiency disorders in a population.

DESIGN

Comparative cross-sectional investigation in two regions in Denmark with marginally different iodine excretion.

METHODS

A random selection of 4649 participants from the Civil Registration System in Denmark in age groups between 18 and 65 years were examined. Thyroid dysfunction was evaluated from blood samples and questionnaires, and compared with results from ultrasonography.

RESULTS

Median iodine excretion was 53 microg/l in Aalborg and 68 microg/l in Copenhagen. Previously diagnosed thyroid dysfunction was found with the same prevalence in the regions. Serum TSH was lower in Aalborg than in Copenhagen (P=0. 003) and declined with age in Aalborg, but not in Copenhagen. Not previously diagnosed hyperthyroidism was found with the same overall prevalence in the regions, but in age >40 years hyperthyroidism was more prevalent in Aalborg (1.3 vs 0.5%, P=0.017). Not previously diagnosed hypothyroidism was found more frequently in Aalborg (0.6 vs 0.2%, P=0.03). Hyperthyroidism was more often associated with macronodular thyroid structure at ultrasound in Aalborg and hypothyroidism was more often associated with patchy thyroid structure in Copenhagen.

CONCLUSIONS

Significant differences in thyroid dysfunction were found between the regions with a minor difference in iodine excretion. The findings are in agreement with a higher prevalence of thyroid autonomy among the elderly in the most iodine-deficient region.

Goitre prevalence and thyroid abnormalities at ultrasonography: a comparative epidemiological study in two regions with slightly different iodine status

OBJECTIVE

The association between severe iodine deficiency and endemic goitre is well established, but little information is available on the relation between milder degrees of iodine deficiency and goitre prevalence.

SUBJECTS

In a comparative epidemiological study performed in two regions in Denmark, we examined 4649 subjects from the general population, women aged 18-65 years and men aged 60-65 years.

METHODS

Ultrasonography and palpation of the thyroid was performed in all participants. Iodine excretion was measured in casual urine samples. Previous thyroid disease was detected by questionnaires, personal interviews and tracing of records.

RESULTS

The median iodine excretion was 61 microg/l (mild iodine deficiency (ID)) and 45 microg/l (moderate ID) in the two regions. Median thyroid volume at ultrasonography was 11. 9 ml (mild ID) and 13.6 ml (moderate ID), P <0.001, and thyroid enlargement was found in 15.0% (mild ID) and 22.6% (moderate ID), P<0.001. Goitre prevalence increased in both regions with age to the age group 40-45 years, but not after that age. Subjects who had moved from the moderate ID to the mild ID area had the same prevalence of thyroid enlargement as the subjects staying permanently in the mild ID area. Thyroid nodules at ultrasonography were found in 30% in both regions, but nodules were larger and more often palpable in the moderate ID area. Palpable goitre was found in 9.8% (mild ID) and 14.6% (moderate ID), P<0.001. The greatest regional difference in thyroid abnormalities was found among men.

CONCLUSION

Marked differences in the prevalence of thyroid abnormalities were found in these regions with modest differences in iodine excretion.

Review of thyroid cancer cases among patients with previous benign thyroid disorders

A previous register linkage study showed an increased risk of thyroid cancer among patients previously discharged from a hospital with a diagnosis of a benign thyroid disorder. In this study, we have reviewed all available medical records, first to validate the earlier result and second to describe the symptomatology of patients with a history of benign thyroid disorder prior to the cancer diagnosis. The previous study identified 189 patients with a benign and subsequent malignant thyroid disorder. Medical records were obtainable for 156 of these patients and were reviewed. For 104 patients, benign and malignant thyroid diseases were metachronous (a clearly separated disease history of the benign and malignant diseases), and for 48 patients synchronous. In 4 cases, thyroid cancer could not be confirmed. Among patients with metachronous thyroid disorders, all major benign thyroid disorders were represented including hot nodules, diffuse and multinodular toxic and nontoxic goiter. Symptoms preceding diagnosis of thyroid cancer included growth of goiter/nodules, globulus, stridor, hoarseness, and metastasis. No major differences were found among patients with metachronous and synchronous benign and malignant thyroid disorder, apart from the fact that all metastases were found among metachronous cases. This study confirmed the conclusion that patients with a previous history of goiter or nodules have an increased risk of thyroid cancer. However, thyroid cancer still occurs too infrequently to warrant screening in all patients with a previous history of goiter or nodules.

Age- and sex-adjusted iodine/creatinine ratio. A new standard in epidemiological surveys? Evaluation of three different estimates of iodine excretion based on casual urine samples and comparison to 24 h values

OBJECTIVE

The most accurate way to measure urinary iodine excretion in epidemiological surveys is still debated. We propose a new principle of estimating iodine excretion based on casual urine samples.

MATERIAL AND METHODS

A total of 123 24 h urine samples and corresponding casual urine samples were collected from 31 subjects. Iodine excretion was expressed as 24 h iodine excretion and three different estimates: iodine concentration in the casual sample, iodine/gram creatinine in the casual sample, and the new principle-iodine/creatinine ratio in the casual sample, adjusted for expected creatinine excretion of the individual.

RESULTS

All three estimates based on casual urine samples correlated significantly to 24 h values with a r (Pearson) of 0.37 for iodine concentration, 0. 61 for iodine/creatinine ratio and 0.62 for the age- and sex-adjusted iodine/creatinine ratio. The median iodine excretion in the entire group was 143 microg/day in 24 h samples, 87 microg/l as iodine concentration, 77 microg/g creatinine as iodine/creatinine ratio and 126 microg/day as age- and sex-adjusted iodine/creatinine ratio.

CONCLUSION

Age- and sex-adjusted iodine/creatinine ratio is a more accurate and unbiased estimate of iodine excretion in epidemiological surveys of adults than the two most frequently used estimated: iodine concentration and iodine/gram creatinine, as these two estimates may introduce a bias depending on the composition of the investigated group. The adjusted iodine/creatinine ratio is superior to the other estimates, especially when individual estimates of 24 h iodine excretion is required or cohorts of selected groups are investigated.

SPONSORSHIP

This work was supported by grants from the Medical Research Foundation Region Greater Copenhagen, Faroe Islands and Greenland; the Wedell-Wedellsborg Foundation; Musikforlaeggerne Agnes and Knut Morks Foundation.

Thyroid structure and size and two-year follow-up of solitary cold thyroid nodules in an unselected population with borderline iodine deficiency

OBJECTIVE

Multinodular goitre has been found with a high prevalence in iodine-deficient areas, but less frequently in iodine-replete areas; the iodine intake sufficient to prevent goitre has not been established, however.

METHODS

We report data from an ultrasonic investigation of the thyroid glands of 2656 randomly selected subjects aged 41 to 71 years in an area with borderline iodine deficiency.

RESULTS

Median iodine concentration in spot urine samples was 70microg/l. Multinodular thyroid structure was found in 23% of the population, increasing in women from 20 to 46% with increasing age, and in men from 7 to 23%. Solitary, scintigraphically cold, thyroid nodules >10mm were found in 2.4% of the population with the same prevalence in the different age and sex groups. Two years of follow-up of these cold nodules revealed no signs of malignancies. Median thyroid volume was 11.0ml. Thyroid enlargement (>18ml for women and >25ml for men) was found among 13. 1% of the women and 6.2% of the men, and the prevalence increased with age. The presence of thyroid nodules was related to positive anti-thyroperoxidase antibody (TPO Ab) titres, whereas thyroid enlargement was associated with iodine excretion <50microg/day.

CONCLUSIONS

Thyroid enlargement was associated with low iodine excretion and median thyroid volume was slightly increased compared with iodine-replete areas. Multinodular thyroid structure was found with a high prevalence and was associated with TPO Ab >200kU/l. Cold thyroid nodules were moderately prevalent, with no cases of detected malignancies during 2 years of follow-up.

Sedation in the intensive care unit

OBJECTIVE

To describe the goals of sedative use in the intensive care unit and review the pharmacology of commonly used sedative drugs as well as to review pertinent publications in the literature concerning the comparative pharmacology of these drugs, with emphasis on outcomes related to sedation and comparative pharmacoeconomics.

DATA SOURCES

Publications in the scientific literature.

DATA EXTRACTION

Computer search of the literature with selection of representative articles.

SYNTHESIS

Proper choice and use of sedative drugs is based on knowledge of the pharmacology of commonly used agents and is an essential component of caring for patients in the intensive care unit. The large variability in pharmacokinetics and pharmacodynamics in the critically ill make it difficult to directly compare agents. Midazolam provides rapid and reliable amnesia, even when administered for low levels of sedation. Propofol may be useful when deeper levels of sedation and more rapid awakening are required. Lorazepam can be used for long-term sedation in more stable patients if rapidity of effect is not required. Further investigation in assessment of depth of sedation in the critically ill is needed. Continued study of costs, side effects, and appropriate dosing strategies of all sedative agents is needed to answer questions not sufficiently addressed in the current literature.

CONCLUSION

An individualized approach to sedation based on knowledge of drug pharmacology is needed because of confounding variables including concurrent patient illness, depth of sedation, and concomitant use of analgesic agents. (Crit Care Med 2000; 28:854-866)

Validation of ultrasonography of the thyroid gland for epidemiological purposes

Ultrasonography of the thyroid is often used in epidemiological surveys, thus thorough characterization of the interobserver variation of the different parameters obtained is important. Various methods have been used for measuring thyroid volume, and different formulas have been used for calculation of thyroid volume from the measured dimensions. In this article, two principles of thyroid volume measurement are described in detail: the wellknown method based on the three axes of each lobe and a new principle based on planimetry in two planes. The interobserver variation of the examination and the measuring procedure in itself were tested on 25 participants in a population study. A comparison of postmortem ultrasonography of the thyroid and results of an autopsy was performed. Good correlation and agreement between observers was found for thyroid volume (r = 0.98) and prevalence of thyroid nodules (kappa = 0.72), whereas echogenecity and echopattern showed little agreement. The correlation of thyroid volume by ultrasonography to autopsy results was satisfactory (r = 0.93), but the volume tended to be slightly underestimated even when using the formula pi/6(= 0.52)*length*width*depth. No major differences were found between the performance of the two principles of volume calculation. We conclude that when the measuring procedure is well defined, results of ultrasonography are comparable between observers for thyroid volume and prevalence of thyroid nodules, but not for echogenecity or echopattern. The formula of length*depth*width*pi/6 is suitable for thyroid volume measurement.

The prevalence of thyroid dysfunction in a population with borderline iodine deficiency

OBJECTIVE

We lack information on the influence of borderline iodine deficiency on the occurrence of thyroid dysfunction. Iodine deficiency has been reported to facilitate the development of toxic nodular goitre, whereas a high iodine intake may increase the prevalence of autoimmune hypothyroidism.

SUBJECTS AND METHODS

In a cross-sectional study of a random sample of the general population in our region with borderline iodine deficiency 2656 (65%) of 4073 men and women aged 41 to 71 years participated. Records were made of previous thyroidal illness. Blood samples were drawn for thyroid parameters and TPO Ab values. Iodine and creatinine was assessed in casual urine samples.

RESULTS

Previous or present hyperthyroidism was reported by 1.4% of the participants whereas 0.6% had unknown biochemical hyperthyroidism. All cases of undiagnosed hyperthyroidism were among women. Previously diagnosed and treated hypothyroidism was reported by 1.0% and undiagnosed hypothyroidism was found in 0.4%. Subclinical hyperthyroidism was found in 1.3% and subclinical hypothyroidism in 0.7%. TPO Ab titres >200 kU/l were found in 16.9% of the women and 6.6% of the men, and 83% of participants with TSH >5 mU/l had TPO Ab titres >200 kU/l. Participants with TPO Ab titres between 100 and 200 kU/l had no increased frequency of thyroid dysfunction. The median iodine excretion rate was estimated as 103 microg/day. Serum TSH values were higher in women than in men and showed higher dispersion in women as well as in old age. Serum free T3 was found to be higher in women than in men and increased with age. Serum free T4 showed no sex difference but values increased with increasing age.

CONCLUSION

In our region with borderline iodine deficiency more than 5% of the general population has clinical or subclinical thyroid dysfunction. We found a relatively high prevalence of hyperthyroidism, especially previously undiagnosed disease, but a low prevalence of hypothyroidism as would be expected in an area of iodine deficiency. Hypothyroidism was related to TPO Ab titres of >200 kU/l. Thyroid hormone levels varied with age and sex.

Heart rate variability and n-3 fatty acids in patients with chronic renal failure--a pilot study

Patients with chronic renal failure (CRF) often have autonomic cardiac dysfunction, which can be assessed by measuring heart rate variability (HRV). This dysfunction prediposes the patients to sudden cardiac death. This study describes 24-hour HRV in patients with CRF compared to HRV in patients with a previous myocardial infarction (MI). Furthermore, associations between HRV in patients with CRF and the content of n-3 polyunsaturated fatty acids (PUFA) in cell membranes were examined, because n-3 PUFA may improve HRV. Twenty-nine patients with CRF treated with dialysis were enrolled. A 24-hour Holter recording was obtained at baseline and the HRV variables, RR (= mean of all normal RR intervals during the 24-hour recording) and SDNN (= standard deviation of all normal RR intervals in the entire 24-hour recording) were analyzed. Also, granulocyte fatty acid composition was determined. The patients were allocated to dietary supplementation with either 5.2 g of n-3 PUFA or a placebo oil (olive oil) daily for 12 weeks in a double-blind design. At the end of the supplementation period the Holter recording and blood sampling were repeated. At baseline the CRF patients' mean SDNN ws 86 ms compared to 118 ms (p < 0.01) in patients with a previous MI. After supplementation with either n-3 PUFA or placebo a highly significant correlation was observed between the content of n-3 PUFA in cell membranes and HRV (r = 0.71, p < 0.01). Furthermore, when the patients were dichotomized according to their mean SDNN, it was found, that those with the highest SDNN had a higher content of n-3 PUFA in cell membranes compared to those with the lowest SDNN (7.8% vs 4.2%, p < 0.05). In conclusion, HRV was decreased in CRF patients indicating a cardiovascular autonomic dysfunction. The positive correlation between the n-3 PUFA content in cell membranes and HRV suggests that the effects of an increased intake of n-3 PUFA in CRF patients should be further studied.

Thyroid hormone treatment aiming at reduced, but not suppressed, serum thyroid-stimulating hormone levels in nontoxic goitre: effects on bone metabolism amongst premenopausal women

OBJECTIVES

To study the effects of six months' treatment with either T4 or T3, aiming at reduced but not totally suppressed serum TSH levels, as measured by a third generation TSH assay, on biochemical bone turnover parameters as well as bone mass in patients with nontoxic goitre.

DESIGN

Prospective randomized study with a matched control group, not blinded.

SETTING

Two University Hospital Clinics in Copenhagen.

SUBJECTS AND INTERVENTION

Twenty-four consecutive premenopausal women with moderate sized nontoxic goitre. Fourteen patients randomized to T4 or T3 treatment for six months with monthly titration of the dose, aiming at TSH values between 0.005 and 0.2 mUL(-1). Ten controls.

MAIN OUTCOME MEASURES

Serum parathyroid hormone (PTH), serum procollagen I C-terminal propeptide (PICP), serum alkaline phosphatase, serum osteocalcin, u-pyridinoline, u-deoxypyridinoline, u-hydroxyproline. Bone mass (BMD) at the lumbar spine and at both femoral necks.

RESULTS

Serum TSH was generally kept within the desired interval. There was no difference in any marker of bone metabolism between the effects of T4 and T3. Consequently, these groups were combined in order to evaluate the effect of thyroid hormones on the bone and mineral metabolism. Thyroid hormone treatment resulted in increased levels of serum ionized calcium (Ca) (P=0.02), serum alkaline phosphatase (P=0.007), serum-PICP (P=0.003), serum osteocalcin (P=0.02) and urinary excretion of deoxypridinoline (P=0.03) compared to untreated controls. Bone mass did not change.

CONCLUSION

Six months treatment with either T4 or T3 of premenopausal women with nontoxic goitre, aiming at reduced but not totally suppressed TSH values, resulted in biochemical signs of increased bone turnover, whereas bone mass remained unaltered. No differences were found between the effects of T4 or T3 treatment.

Development of hyperthyroidism in nodular goiter and thyroid malignancies in an area of relatively low iodine intake

A high incidence of toxic nodular goiter has recently been described in areas of relatively low iodine intake. We studied the development of hyperthyroidism in nodular goiter and thyroid malignancies in an area of relatively low iodine intake (median 87 micrograms/h). The material comprised a total of 557 patients admitted to our department in the period 1978-88. The follow-up material consisted of 214 patients with a median age of 55 yr (19-86). Eighty-eight percent were females. The period of observation was 33 months (1-205). All patients had technetium thyroid scans, serum T3, serum T4, T3 uptake test and serum TSH performed. TRH tests were performed in 58 patients. During the follow-up period 45 initially euthyroid patients became hyperthyroid (18%). The incidence increased with age, and the median age in the group, who developed hyperthyroidism, was 65 yr. An estimated minimal incidence of toxic nodular goiter was 23/100,000/yr. Contrary to previous assumption, hyperthyroidism developed frequently in elderly patients with nodular goiter in a low iodine intake area. Thyroid cancer was found in 13 patients corresponding an estimated incidence of 1.5/100,000/yr. The cancer incidence was very low compared to other nordic countries with high iodine intake. This finding may suggest a possible influence of iodine intake on the incidence of thyroid cancer.

Long-term topical nitrogen mustard treatment does not induce pulmonary fibrosis in MF patients

Eleven patients with mycosis fungoides had X-ray examinations of their lungs before, during and after topical treatment with mechlorethamine. The mean number of treatments was 163, ranging from 28 to 300 treatments within a period of 1 to 13 years (mean 7.8 years). Each exposure to the skin of mechlorethamine was between 20 and 40 mg giving a cumulative dosage in the range from 1.120 mg to a maximum of 12.000 mg. We looked for potential lung damage from mechlorethamine vapours, such as fibrosis of the lungs, but found none. Thus, we conclude that topical treatment with mechlorethamine of patients with mycosis fungoides is not only an effective treatment, but also a safe therapy.

Malignant pleural mesothelioma

Malignant pleural mesotheliomas are tumors originating in the serosal lining of the pleural cavities. Although these are relatively rare tumors, an increasing number of cases are anticipated over the next decade. Patients with these tumors, which are almost invariably fatal, usually have an interval of less than two years between the onset of symptoms and death. There is a well established link between mesothelioma and asbestos exposure. Treatment includes surgery, chemotherapy, and radiotherapy. This article explores the epidemiology and etiology of the disease, offers a summary of current treatment options, and discusses nursing strategies.

Seasonal variation in thyroid size in healthy males

Thyroid volume, measured ultrasonically, and serum levels of T4, T3 and TSH were determined every season during one year in 13 healthy males. A mean variation in thyroid volume of approximately 23% between minimum values (15.8 +/- 1.7 ml, summer) and maximum values (19.5 +/- 1.9 ml, winter) was found (P less than 0.01), although no significant differences in the other thyroid variables could be demonstrated. This seasonal variation in thyroid size should be taken into account when goitre frequency, goitrogenic action of drugs, and goitre treatment effects are evaluated.

Simultaneous registration of sleep-stages and bladder activity in enuresis

A combined monitoring of sleep stages and bladder activity for the evaluation of enuresis is on trial. Polygraphic recordings in 7 patients, comprising the preliminary material, have shown single-event bladder contractions without forewarning or changes in sleep stages. A volume dependency of the enuresis episodes seems so far to be a major mechanism.