Evidence of weak ferromagnetism in doped plasticized polyaniline (PANI-DDoESSA)0.5 from electron spin resonance measurements.

X-band electron spin resonance (ESR) measurements have been performed on a conducting free-standing film of polyaniline plasticized and protonated with di-n-dodecyl ester of sulfosuccinic acid (DDoESSA). The magnetic field was applied parallel and perpendicular to the plane of the film. At around 75 K a transition is observed from Pauli susceptibility to a localized state in which the spin 1/2 polarons behave as spin 1/2 dimers. A rough estimation of the intradimer and interdimer exchange constants is obtained. Below 5 K, ESR data reveal a weak ferromagnetism with the Dzyaloshinskii-Moriya vector mainly oriented in the plane of the film. The existence of a relatively well-defined n-fold axis along the chain direction in the crystalline regions confers a symmetry compatible with such analysis.

Magnetic field dependence of the magnetic susceptibility and the specific heat of the doped plasticized polyaniline (PANI-DB3EPSA)0.5.

Specific heat, magnetization and electron spin resonance (ESR) data obtained from a self-standing film of the doped plasticized polyaniline (PANI-DB3EPSA)(0.5) are shown. No long range magnetic order has been observed at zero magnetic field, above 2 K. For a magnetic field of 3.3 kOe applied perpendicular to the plane of the film, a clear signature of an induced ordered state can be seen in the specific heat data and ESR also reveals this antiferromagnetic order. An electronic contribution is detected from ESR, magnetization and specific heat; however, for T ≤ 5 K, the specific heat data show the existence of a gap. Magnetization data also show a low temperature dominant Curie behaviour which cannot be seen from ESR, probably due to a very large linewidth, suggesting short range correlations among spin 1/2 polarons.

Counter-ions dynamics in highly plastic and conducting compounds of poly(aniline). A quasi-elastic neutron scattering study.

Proton dynamics in films of poly(aniline) "plastdoped" with di-esters of sulfophthalic (or sulfosuccinic) acids have been investigated by using quasi-elastic neutron scattering techniques. A broad time range (10(-13)-10(-9) s) has been explored by using four different spectrometers. In this time range, the dynamics is exclusively due to protons attached to the flexible tails of the counter-ions. A model of limited diffusion in spheres whose radii are distributed in size gives a realistic view of the geometry of molecular motions. However, it is found that the characteristic times of these motions are widely distributed over several orders of magnitude. The time decay of the intermediate scattering function is well described by a time power law. This behaviour is qualitatively discussed in connection with the structure of the systems and by comparison with other so-called complex systems.

Assessment of wall structure and composition of varicose veins with reference to collagen, elastin and smooth muscle content.

OBJECTIVES: To compare collagen, elastin and smooth muscle contents of varicose and control long saphenous veins. DESIGN: Collagen, elastin and muscle were estimated stereologically using random sampling and histological staining. MATERIALS: Varicose vein samples were collected from nine patients (mean age 52 years, range 34-64 years) undergoing vein stripping, sample sites being saphenofemoral junction and knee. Control samples were taken from five patients (mean age 58 years, range 38-76 years) presenting for femoral-popliteal bypass at equivalent levels. METHODS: Veins were fixed, sectioned transversely, and stained with Picric Acid Sirius Red. Analysis of samples was performed using point and intersection counting on vertically projected images. RESULTS: Using two way analysis of variance tests, varicose saphenous veins had significantly larger wall areas (p < 0.01) and higher amounts of collagen (p < 0.01). Collagen content and wall area were significantly larger proximally compared to distally in both control and varicose veins (p < 0.05) with a higher content of smooth muscle and elastin in varicose veins proximally compared to distally (p < 0.05). There was no difference in wall thickness or elastin content between the two groups. CONCLUSIONS: This suggests that varicose veins are a dynamic response to venous hypertension and are not thin walled structures as previously thought.

Stereological studies on red corpuscle size produce values different from those obtained using haematocrit- and model-based methods.

The routine methods for estimating erythrocyte size (volume and surface area) are not generally unbiased. Using geometric models introduces a bias determined by the ways in which real red blood corpuscles depart in size and shape from the simplistic ideal. Employing haematocrit and red corpuscle count to estimate mean corpuscular volume relies on an implicit assumption that erythrocytes fill three-dimensional space. However, a biconcave circular disc cannot be space-filling. The bias is positive and its magnitude depends on erythrocyte geometry and packing density within the centrifuge pellet. We have estimated the volumes, surface areas and shape factors of red blood corpuscles in normal adults (three males, three females) using transmission electron microscopy and stereology. We confirm the lack of sexual dimorphism and find that the mean corpuscular volume is 44 fl (between-subject coefficient of variation 5%), mean membrane surface area is 87 microns2 (6%) and the shape factor is 18.4 fl/fl (11%). The surface is 44% greater than that of a sphere of equal volume. The possible reasons for discrepancies with standard haematological values are discussed. On the basis of observed volumes, we predict that red blood corpuscles account for only 51% of the volume of the red column in standard haematocrit pellets.

Postoperative limb compression in reduction of haemorrhage after varicose vein surgery.

In varicose vein surgery, significant postoperative morbidity results from subcutaneous haematoma formation and limb swelling after saphenous vein stripping. We investigated the effectiveness of a high-compression short-stretch adhesive bandage compared with non-adhesive crêpe in reducing haemorrhage after stripping of varicose veins. Using 99mTc-labelled red blood cells, the degree of postoperative bleeding was assessed in 10 patients with bilateral varicose veins allocated for stripping and ligation. High-compression adhesive bandaging was applied to the experimental limb and a non-adhesive bandage to the contralateral control limb. Results show that adequate compression bandaging can decrease subcutaneous haematoma formation after stripping of varicose veins.

Insulin and insulinlike growth factors in embryonic development. Effects of a biologically inert insulin (guinea pig) on rat embryonic growth and development in vitro.

Congenital anomalies occur up to four times more frequently in diabetic pregnancy than in the nondiabetic population. Although past work has shown that maternal hyperglycemia and hyperketonemia may increase embryonic abnormalities, recent experimental evidence suggests that low insulin levels may also contribute to diabetic embryopathy. This study investigated the effects of guinea pig serum (whose insulin is inactive in rat systems) on rat embryonic growth and development in culture. Supplementation of guinea pig serum with pork insulin at low (1 ng/ml) and high (5 ng/ml) physiological concentrations and insulinlike growth factors (IGF) I and II were also studied. Culture of rat embryos from the early headfold stage in guinea pig serum resulted in poor embryonic growth and development with a 92% rate of anomalies. Supplementation of guinea pig serum with zinc-binding pork insulin significantly improved rat embryonic growth and development (46% anomaly rate) especially between the first 5 and 21 h of the period of organogenesis. This evidence supports our most recent findings that low insulin levels, as encountered in untreated diabetic pregnancy, may contribute to the increased risk of congenital abnormality. Insulin at low physiological concentrations improved growth, whereas higher physiological concentrations were required to increase growth and development. IGF-I or IGF-II supplementation improved rat embryonic growth and development but failed to match that of the controls, indicating that other growth factors including insulin may also be required.

Effects of low insulin levels on rat embryonic growth and development.

The risk of congenital abnormality in diabetic pregnancy is about four times that for the normal population. Past clinical studies have suggested hyperglycemia and hyperketonemia as the factors responsible for these abnormalities, with no reference to the possible effects of low insulin levels. We examine the effect of hypoinsulinemia on rat embryonic growth and development in culture while normal glucose levels are maintained. With anti-insulin antibody bound to an affinity column containing cyanogen bromide-activated Sepharose 4B beads, insulin was selectively removed from the homologous culture serum eluted down the column. A culture of rat embryos from the early head-fold stage for 50 h in insulin-depleted normoglycemic homologous serum (insulin levels 0.055-0.18 ng/ml) showed retardation of growth and development when compared with control embryos. Adding physiological amounts (10 ng/ml) of insulin back into the insulin-depleted serum subsequently restored growth level to that of control embryos. We conclude that low insulin levels, encountered in newly diagnosed diabetic pregnancy, may be instrumental in increasing the risk of congenital abnormalities.

Incidence of sarcoidosis in the Isle of Man.

The incidence of sarcoidosis in a clearly defined island community has been determined in a seven year study. Special efforts were made to identify all cases, including those presenting to their general practitioners with only minor symptoms. A mean incidence of 14.7 per 100 000 per annum has been found in the years 1977-83 compared with an annual incidence of 3.5 per 100 000 in the preceding 15 years, when no specific attempts were made to identify sufferers from sarcoidosis. The lower figure is similar to the reported incidence in the United Kingdom and the difference is considered to be due to increased detection of cases during the study period. These findings suggest that a large proportion of cases of sarcoidosis in a general population may not be recorded in a registration system.

Double-blind clinical trial of topical steroids in anterior uveitis.

We present the results of a double-blind trial comparing the efficacy of betamethasone phosphate 0.1%, clobetasone butyrate 0.1%, and placebo in the treatment of acute unilateral nongranulomatous uveitis. The 2 steroids were equally comparable in improvement of the patients' symptoms, though betamethasone phosphate was significantly more effective than clobetasone butyrate in improving the ocular signs of uveitis. However, clobetasone butyrate had significantly less effect on raising intraocular pressure in known steroid responders and ocular hypertensives than did dexamethasone. The use of a bolometer as an objective measure in uveitis was significant only in the more severe cases of uveitis. In comparing the placebo group of patients with those on topical steroids, the former group, though improving, appeared to lag behind by approximately one week. Four cases on placebo, however, had to be withdrawn because of worsening of the condition. Mild cases of anterior uveitis would probably resolve without using topical steroids.

Topical steroids in anterior uveitis.

The results are presented of a double-blind trial comparing the efficacy of betamethasone phosphate 0.1 per cent, clobetasone butyrate 0.1 per cent, and placebo in the treatment of acute unilateral non-granulomatous uveitis. The two steroids gave comparable results in improvement of the patients' symptoms, although betamethasone phosphate was significantly more effective than clobetasone butyrate in improving the ocular signs of uveitis. In comparing the placebo group of patients with those given topical steroids, the former group, though improving, appeared to lag behind by approximately 1 week. Four patients receiving placebo, however, had to be withdrawn because of worsening of the condition. Mild cases of anterior uveitis would probably resolve without using topical steroids.

A controlled trial of adenine arabinoside and trifluorothymidine in herpetic keratitis.

The effectiveness of two anti-viral agents, adenine arabinoside and trifluorothymidine, were studied in cases of human superficial herpetic keratitis (dendritic ulceration). A highly satisfactory response to each drug was demonstrated in most cases.