SUMMARY We have identified regular thermal patterns over normal knee, ankle, and elbow joints and demonstrate how synovitis affecting these joints may be identified by alteration or loss of the thermal pattern. Sixty healthy volunteers were thermographed on a total of 190 occasions, and 614 out of 618 joints conformed to the normal thermal pattern. Eight-five patients with synovitis of at least one of the specified joints were thermographed on a total of 339 occasions, and 322 out of 1362 thermograms were abnormal. No joint with clinical evidence of synovitis had a normal thermal pattern. As temperature-based parameters have been found to show marked diumal variation and relative frequency distributions do not have this drawback, we suggest that quantification of synovitis by thermography should in future be based on abnormalities of thermal pattern rather than absolute skin temperature values.The objective assessment of disease activity in rheumatoid arthritis is difficult. Many parameters are based on patients' symptoms, which may not give an accurate indication of the progress of the disease, and laboratory evaluation can be unhelpful.' Infrared thermography (IRT) has been used for the past 10 years to measure skin temperature over inflamed joints.23 Horvath and Hollander4 measured the intra-articular temperature in patients with rheumatoid arthritis and noted that it could be used as a guide to the acuteness of inflammation. Bacon et al. 5showed that measurement of mean skin temperature could be used as a measure of disease activity. Skin temperature is affected by many internal and external factors.6 Circadian rhythm, metabolic rate, calorific intake, physical activity, emotional state, and atmospheric temperature and humidity can all exert a marked effect on skin temperature. In particular, owing to the proximity of blood vessels to the skin in the extremities even small alterations in vascular tone will produce large changes in skin temperature.Many of these factors are uncontrollable. In addition, the variation leads to difficulties in standardisation and relating a single measurement to an arbitrary 'normal' temperature.7We therefore set out to examine whether such relation to absolute arbitrary standards is necessary and whether inspection of the thermogram could identify the presence or absence of synovitis. Thermograms of the knee, elbow, and ankle joints of normal subjects have been compared with those from patients with clinical evidence of synovitis. To test the effect of diurnal variation on the methods of analysis serial readings were obtained at different times of day. Methods and patientsThermography. This was carried out in a draught-free room with ambient temperature controlled to 20 5°C + 0 5°C and humidity 50% + 10%. Subjects were seated in a modified dentist's chair with their limbs exposed and a sleeveless jacket worn.An AGA Thermovision 680 medical system was used to detect infrared emission, and all thermograms were recorded in digital form on magnetic tape for subsequent analysis with...

The objective of this study was to determine if males with a deficient androgen receptor would develop hypertension when crossed with a hypertensive parent Female King-Holtzman rats (n=15), heterozygous for the testicular feminization (Tfm) gene, were crossed with male spontaneously hypertensive rats (SHR), and blood pressure was measured weekly from 5-14 weeks in the F, hybrid males. Approximately 50% of the F, hybrid males were Tfm males and androgen receptor-deficient, and 50% were normal. Blood pressure in the parent KingHoltzman males, Tfms, and female rats was also followed for the same time period. The F, normal male hybrids had a significantly higher (p<0.05) systolic blood pressure than the Tfm hybrid males after 12 weeks (195±8 versus 170±8 mm Hg, respectively). Blood pressure in the male and Tfm Holtzman rats was 120±5 mm Hg and 110±6 mm Hg, respectively. Castration lowered blood pressure by 38 mm Hg in the hybrid males and 27 mm Hg in the Tfm hybrids. Female F, hybrids also showed a pressure rise above that of female Holtzman controls (155±6 mm Hg versus 110±6 mm Hg, /><0.01) but lower than the F, males and Tfm hybrids. Ovariectomized females with testosterone implants did not show an elevation in blood pressure. Plasma electrolytes, norepinephrine, and cholesterol were not significantly different between normal and Tfm hybrid males. The results suggest that the presence of an androgen receptor and a testis-derived factor mediate the blood pressure rise in the hybrid males. A Y chromosome effect or sex-influenced locus may be involved since both the normal and Tfm males had significantly higher blood pressures than their female siblings. (Hypertension S ex differences in systolic and diastolic blood pressure by age have been reported in most studies of developed societies. The US Public Health Service National Health Survey, 1 The Tecumseh Study, 2 and similar epidemiological longitudinal studies in Norway, 3 Poland, 4 and Japan 5 have reported that men have higher blood pressure than women at younger ages (second through third decade) with a crossover in women to higher pressures in the fourth to sixth decade. The crossover phenomenon appears to be characteristic of nearly all developed societies and is seen most clearly with systolic pressure. Similar conclusions are reached whether the results are expressed as the mean pressure by age and sex or as prevalence of hypertension. There are only a few blood pressure studies in children, but available data suggest that there are no significant sex differences. 6 These studies and experimental studies suggest that the male sex hormones, specifically testosterone, play a role in the sexual differentiation of hypertension.

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SUMMARY Standard clinical methods of assessing joint inflammation are being supplemented increasingly by radioisotopic and thermographic studies. However, the correlation between these different methods has not been firmly established. In the quantification of synovitis by infrared thermography we have shown that the heat distribution index (HDI) based on thermal pattern is more reliable and is less affected by diurnal variations in joint temperature than the commonly used thermographic index, which is based on average skin temperature values. In 20 patients with rheumatoid arthritis whose knees were being treated with intra-articular steroid we obtained 184 serial paired observations over a period of 24 weeks for clinical assessment, HDI, and 99mTc pertechnetate uptake. We found significant correlations (p<0.001) between the three methods of assessment (except for pain and HDI (p=0116)).

Clinical assessment, plasma and synovial fluid kinetics were studied in 29 rheumatoid patients receiving 100 mg flurbiprofen twice daily. Clinical assessment and pharmacokinetic measurements varied widely within the group of patients. The average values for plasma clearance, volume of distribution and elimination halflife of flurbiprofen were 0.65 +/‐ 0.24 ml min‐1 kg‐1, 0.160 +/‐ 0.093 l kg‐1 and 3.1 +/‐ 1.7 h, respectively. Synovial fluid drug concentrations peaked later and were lower than corresponding plasma concentrations: 5.2 h and 4.4 mg l‐1 as against 1.49 h and 12.5 mg l‐1, respectively. At 48 h after an oral dose of flurbiprofen, all the drug had been cleared from the synovial fluid. Synovial fluid drug concentrations were not related to synovial fluid albumin concentration or pH. There was a weak relationship between synovial fluid drug concentration and the thermographic measurements of disease activity. The fractions of flurbiprofen not bound to protein in synovial fluid and plasma were not significantly different. A simple model is proposed to account for the plasma and synovial fluid pharmacokinetics.