Recent and episodic volcanic and glacial activity on Mars revealed by the High Resolution Stereo Camera.

The large-area coverage at a resolution of 10-20 metres per pixel in colour and three dimensions with the High Resolution Stereo Camera Experiment on the European Space Agency Mars Express Mission has made it possible to study the time-stratigraphic relationships of volcanic and glacial structures in unprecedented detail and give insight into the geological evolution of Mars. Here we show that calderas on five major volcanoes on Mars have undergone repeated activation and resurfacing during the last 20 per cent of martian history, with phases of activity as young as two million years, suggesting that the volcanoes are potentially still active today. Glacial deposits at the base of the Olympus Mons escarpment show evidence for repeated phases of activity as recently as about four million years ago. Morphological evidence is found that snow and ice deposition on the Olympus construct at elevations of more than 7,000 metres led to episodes of glacial activity at this height. Even now, water ice protected by an insulating layer of dust may be present at high altitudes on Olympus Mons.

Utility of thyroid aspiration biopsy.

The utility of fine-needle aspiration biopsy to detect carcinoma in thyroid nodules was evaluated by a decision-analysis approach in 102 patients. The procedure caused no morbidity. Cytologic diagnoses were categorized as unsatisfactory (4), no abnormality detected (61), atypical (13), suspicious for malignancy (14), malignancy (2), and inflammation (8). The duration of follow-up averaged 13 months. Of 21 thyroidectomy patients, 10 (48%) had carcinoma. Half of the ten patients operated upon for suspicious cytologic findings were found to have malignancy. Assuming criterion I, that atypical, suspicious, or malignancy results indicated cancer, sensitivity was 90%, specificity 77%, false positive fraction 23%, positive predictive value 31%, negative predictive value 99%, and accuracy 79%. Assuming criterion II, that only suspicious or malignancy cytologic findings represented carcinoma, sensitivity was 70%, specificity 90%, false positive fraction 10%, positive predictive value 44%, negative predictive value 96%, and accuracy 88%. We conclude that sensitivity and specificity of fine-needle aspiration biopsy vary depending upon the use of criterion I or II. Accuracy is highest if atypical results are not considered to represent carcinoma. Positive predictive values remain low and negative predictive values are high in either case. The utility of fine-needle aspiration biopsy when interpreted in relation to clinical criteria is supported by these results.

Graves' disease following acute (subacute) thyroiditis.

The development of Graves' disease with positive thyroid-stimulating antibody titers is described in a woman, five months after onset of the putatively viral disorder, acute (subacute) thyroiditis. There was no evidence of transient hyperthyroidism during the acute episode. The arguments for and against a causal relationship between the two diseases have been reviewed. The present experience adds to the earlier suggestion that the association may represent cause and effect.

Modification of the classification of the eye changes of Graves' disease.

The original (1969) classification of the Eye Changes of Graves' Disease has been retained except for Classes 1 and 3. Class 1 has been limited so that proptosis of 23 mm or greater is placed in Class 3, even if the patient is asymptomatic. Grading of Classes 1 and 2 has been left to the individual physician or clinic, but we urge that the suggested criteria for grading Classes 3 through 6 be used. Progression of disease is not necessarily sequential through each of the classes, and ethnic factors and myopia may influence the extent of proptosis in normal subjects.

Similar serum IgM concentrations in Greek endemic goiter and control populations: failure to confirm previous experience.

Circulating immunoglobulin M (IgM) concentrations were determined in 47 nontoxic goiter patients from four Greek endemic goiter areas, and in 13 patients from Athens, a non-goitrous area; and compared with 38 control non-goitrous subjects from the same goiter regions, and 23 more controls from Athens. The values in both goitrous and non-goitrous groups were indistinguishable. Current techniques for single radial immunodiffusion were employed. The results are expressed in standardized international units/ml serum, instead of the formerly used mg/dl. The present findings are in disagreement with the earlier observation from this laboratory that 40 per cent of goitrous patients had elevated IgM values compared with 10 per cent of control subjects.

Excessive thyrotropin concentrations in the circulation of the spontaneously hypertensive rat.

Thyroid funct-on in SHR was compared to that of inbred normotensive Wistar rats from Kyoto, and random bred Wistar rats from the United States. A marked increase in circulating thyrotropin concentration was found in SHR compared to controls. Serum thyroxine and T3 concentrations relative to controls, however, were variable and the concentrations in male and female SHR relative to Kyoto controls did not correspond with each other. No ready explanation for the circulating excess of thyrotropin, with mimimal increase in T4 and T3 concentrations, is available.