Endothelium-derived relaxing factor (EDRF) and resistance vessels in an intact vascular bed: a microangiographic study of the rabbit isolated ear.

1. Microradiographic techniques have been used to show that endothelium-derived relaxing factor (EDRF), which is believed to be nitric oxide, influences vasomotor responses in small arteries and arterioles down to 25 micron in diameter in an isolated, intact, buffer-perfused ear preparation of the rabbit. Arteries down to 75 micron in diameter, i.e. the central ear artery (G0) and its first three generations of branch vessels (G1, G2 and G3) were studied quantitatively. 2. Relative constrictor responses to 1 micron 5-hydroxytryptamine (5-HT) and the combination of 1 microM 5-HT and 1 microM histamine diminished progressively from G0 to G3. Constrictor responses to 5-HT were doubled in all generations by 1 microM haemoglobin which abolishes EDRF activity. 3. Relative dilator responses to acetylcholine or to substance P in preconstricted arteries were, in contrast, equal in the different generations. Mean -log (IC50) values calculated from diameter measurements were 7.63 +/- 0.10 M and 9.80 +/- 0.11 M, respectively. These dilator responses were abolished by 1 microM haemoglobin, implying that they were EDRF-mediated. Spatial homogeneity of relative dilator responses was found also with glyceryl trinitrate (10 or 50 microM) whose activity is thought to depend on biotransformation to nitric oxide, in both the presence and the absence of haemoglobin. 4. This finding of spatial homogeneity of the diameter response to changes in EDRF activity (or to glyceryl trinitrate) implies that EDRF influences hydrodynamic resistance more in vessels where constrictor tone is high.

In vivo and in vitro assessment of barium sulphate suspensions.

In vitro methods of testing the efficiency of barium sulphate suspensions in delineating mucosal detail using canine cadaveric stomachs have been described in the literature. In this study a comparison is made between in vitro and in vivo tests in the stomach and small intestine of dogs, using several brands of barium sulphate. The results indicate that there is considerable variation in the behavior of these suspensions between the in vitro and in vivo tests particularly in the stomach. It is our view that in vitro tests of this sort are of little value for assessing the relative advantages and disadvantages of these suspensions in demonstrating mucosal detail.

Observations on the behaviour of barium sulphate suspensions in gastric secretion.

A number of barium sulphate suspensions showed varying patterns of stability when provoked with gastric secretion. The stability of the suspensions was affected by the pH, the mucin content and the volume of secretion used. These studies indicate that flocculation of the suspension in the presence of gastric residue decreases as the amount of undiluted barium sulphate in the mixture is increased.

The correlation of histopathological, microradiographic and ultrasonographic features in disease of the prostate gland.

The histopathological, microradiographic and ultrasonographic features of corresponding areas of 100 cadaveric prostates were examined and correlated statistically to investigate their relationship. Benign glands are seen to be related to reticular structure and mid-range echoes. Benign prostatic hyperplasia is related to microadenomatous structure and mid-range echoes, whilst cancer is related to amorphous structure and low echoes. A small number of cancers have irregular calcification present and these tumours are related to high echoes. The structure of the prostate gland is therefore related to its pathology and explains its ultrasound echogenicity.

Shear modulus-temperature meltdown profiles of gelatin and pectin gels. A cascade theory description.

In this paper, a cascade theory approach to biopolymer gelation is developed to describe variation of the shear modulus with temperature for thermoreversible gels. The broadness of this 'melting transition' is seen to depend crucially on the enthalpy of cross-linking, while the critical gel melting temperature is determined by additional factors such as the entropy of cross-linking, the polymer concentration, the molecular weight, and the number of cross-linking sites. On using the model to fit experimental data for specific gelatin and pectin systems, it was found that the behaviour of gelatin (sharp melting transition and low melting temperature) is a consequence of the large negative enthalpy and entropy of cross-linking, while, in contrast, the broad melting transition and high melting point of the pectin system are consistent with much smaller negative values for these parameters.

Forensic radiology.

Like any branch of medicine, radiology has an interface with the law. This has two main facets: first the technical applications of radiology to forensic problems and secondly the legal aspects of radiological practice.

Where do all the tablets go?

Barium sulphate tablets, identical in size and shape to those of aspirin, were given to 98 consecutive patients during routine radiological studies of the upper gastrointestinal tract. In 57 patients the tablets remained in the oesophagus for longer than five minutes. Delay in passage of the tablets was particularly likely to occur in patients with hiatus hernia and reflux and if defects of peristalsis in the oesophagus were observed.

Comparative pelvimetric measurements in Nigerian and Welsh women.

The authors compared the pelvic measurements of a group of Nigerian women with those of a similar group of Welsh women. The Nigerian pelvis is smaller than the Welsh especially when account is taken of the Nigerian women being taller. Base-line data for radiologists working in Nigeria are provided.

Coarse mucosal folds in the duodenum: a twenty-year follow-up.

In a 20-year follow-up of 40 patients with coarse duodenal folds, details were obtained about 34 patients of whom 11 had died. Clinical details were reviewed from the remaining 23 patients, and recent barium meal examinations were reviewed from eight patients. Ten of the 23 surviving patients continued to have recurrent dyspepsia, and the radiological appearance in three of the eight recent barium meals showed that coarse mucosal folds persisted. The clinical course of those with coarse duodenal folds is similar to that of peptic ulcer, with recurrent symptoms in some patients continuing for many years, and in others complicated by development of peptic ulcer. Coarse mucosal folds in the duodenum are usually associated with a high acid secretion and treatment to reduce acid secretion is appropriate in view of the severity of symptoms and risk of ulceration.

Inter-sterno-costo-clavicular ossification.

The clinical and radiological features of four patients with inter-sterno-costo-clavicular ossification are described. The process was associated with established seronegative spondyloarthropathy in three cases of whom four had long standing psoriasis, the other having ankylosing spondylitis. In the fourth case no associated arthropathy was present. A review of the literature is presented.

Antenatal attendance and screening for neural tube defects.

An analysis of factors influencing the time of booking at seven hospital antenatal clinics in one Health Authority Area showed that only 52.5 per cent of patients booked before 16 weeks gestation and 78.9 per cent before 19 weeks gestation. The principle reasons for late booking were delay in the patient seeking medical advice and delay in referral to hospital by the general practitioner (GP) after pregnancy was confirmed. Possibilities for improving early attendance and hence implementing an effective screening programme for the detection of neural tube defects are discussed.

Natural history of patients with x-ray-negative dyspepsia in general practice.

When 102 patients with dyspepsia who had normal findings on barium-meal examination in 1964 were interviewed in 1970, 85 of them (76%) were symptomatically improved, and only three were later shown to have a peptic ulcer. This suggests that "x-ray-negative dyspepsia" has a good prognosis in a general practice setting.