Infrared and visible fourier-transform spectra of sulfuric-acid-water aerosols at 230 and 294 K.

The extinction spectra of aqueous sulfuric acid aerosols fully covering the mid-IR to visible regions from 750 to 23,000 cm(-1) (13.9-0.4 microm) have been measured in the laboratory with a Fourier-transform spectrometer. Both large and small aerosol particles with compositions of approximately 60-70-wt. % H(2)SO(4) were generated and their spectra recorded at 230 and 294 K. The spectra were fitted to a model incorporating room-temperature refractive-index data [Appl. Opt. 14, 208 (1975)] and Mie theory calculations to characterize the composition and size distributions of the aerosol samples.

UV-B Robertson-Berger meter characterization and field calibration.

The New Zealand Meteorological Service has used a Robertson-Berger meter (RB meter) to monitor solar UV-B radiation for the past decade. The radiometric properties of the instrument have been analyzed and agree with the standard values published by Berger. A detailed theoretical treatment of the RB meter response that fully accounts for its cosine response is presented. Field measurements made with the RB meter and with a double monochromator spectral radiometer were used to validate the theoretical model and to derive a calibration for the RB meter. Only cloud-free data were considered so that the downward radiation field at the surface could be modeled as the sum of direct solar and isotropic diffuse components. The imperfect cosine responses of both instruments were modeled. A RB meter count was found to equate to 0.25 +/- 0.02 Jm(-2) referenced to 300-nm radiation at vertical incidence.

Radiological contrast media.

1. This author believes that the present evidence (water shifts and vasodilatation) strongly indicates that low osmolality is probably the main advantage of the new contrast media. 2. Arteriographic adverse reactions (pain, vasodilatation) are less marked with the contrast medium of the lowest osmolality--i.e. ionic ioxaglate salts. 3. Minor adverse reactions (nausea and vomiting) are less marked with some non-ionic media (e.g. iohexol, iopamidol) than with ioxaglate but there are no data concerning the relative incidence of severe reactions or fatalities. 4. Dr. Lasser's suggestion in 1987, that 12 hours of corticosteroid prophylaxis reduces the adverse reaction rate of intravenous HOCM to the rate of LOCM reactions, awaits confirmation. However, corticosteroid prophylaxis will not reduce the side effects due to hyperosmolality, e.g. vasodilation, hypervolemia, and pain (on arterial injection). 5. Unless and until the necessary finances are available, I suggest LOCM (costing 12 times the price of HOCM in Canada and America) be used on a selective and discriminatory basis in three groups of patients: those undergoing painful procedures (e.g. peripheral arteriography), those undergoing potentially dangerous procedures (e.g. spinal angiography, coronary angioplasty) for patients considered on account of their previous medical history (e.g. asthma, allergy, previous adverse reactions, cardiac failure) to be at greater risk than the normal population.

Fistula and sinus formation in xanthogranulomatous pyelonephritis. A clinicopathological review and report of four cases.

Fistula or deep sinus formation as a complication of xanthogranulomatous pyelonephritis (XPN) has not been described previously in the British literature. We present the clinicopathological features of one case of a nephrodiaphragmatic sinus complicating XPN, and three cases of nephrocolic fistula, including the first recorded case of fistula in childhood XPN. The detailed clinical, radiological and pathological features of XPN and its complications are reviewed. Total nephrectomy, together with primary excision of sinuses or fistulae, is the treatment of choice.

The optimal concentration of contrast medium for aortography and femoral arteriography: a comparison of Hexabrix 320 and Hexabrix 250.

A prospective double-blind randomised clinical trial of aortography and iliofemoral arteriography in 89 patients demonstrates that there is no difference in the diagnostic quality of the studies when Hexabrix 250 replaces Hexabrix 320. There is a minor reduction in patient subjective reaction, and the lower viscosity permits the use of smaller bore catheters. The major gain is that the cost of the contrast medium should be reduced by 22%.

The pulmonary circulation: the radiology of adaptation.

In this George Simon Lecture, I have tried to present a simplistic yet philosophical approach to the physiological processes of adaptation of circulatory and respiratory function in response to pathophysiological challenge. The objective of the body is to achieve a normal ventilation-perfusion ratio of 1 in order to optimise blood-gas exchange in a wide variety of pathological conditions. It is all a question of the right ingredients (oxygen in atmospheric air and reduced haemoglobin in desaturated blood), in the right copious amounts (100 ml/s), in the right proportion (1:1) and in the right place (alveolar capillary membrane). In order to demonstrate the above concepts, a variety of well known conditions, congenital and acquired, have been discussed in the developing infant lung and the adult mature lung; some primarily cardiovascular, others primarily respiratory; some conditions resulting in permanent and others resulting in temporary and reversible major readjustments of the blood supply to the lung. The emphasis has been to illustrate that simple, unsophisticated radiological techniques may provide a substantial amount of valuable information concerning the remarkable capacity of the pulmonary circulation to adapt to varying physiological or pathological demands in order to conserve our precious respiratory resources. George Simon, like all good doctors, had a tremendous respect for the ability of the body to respond to these challenges. He always emphasised the important basic principles rather than fine minutiae. It is hoped that this lecture in his honour follows these principles which he preached so well.

Xanthogranulomatous pyelonephritis: a pathological, clinical and aetiological analysis of 87 cases.

Analysis of 87 cases of xanthogranulomatous pyelonephritis ( XPN ) from 1958 to 1983 (14 males, 73 females, ages 13-85) revealed an incidence of 1.4 cases/100 000 population per annum which is apparently increasing. Clinical, radiological and pathological investigations demonstrated universal urinary obstruction (77.5 per cent calculi, 17.5 per cent pelviureteric junction obstruction) and pathogenic organisms such as E. coli or Proteus were cultured from the urine in 72 per cent of cases. Rare complications included sinuses or fistulae to bowel. We believe that the combination of urinary obstruction and infection by organisms of low virulence initiate XPN , and that associated lipid is derived from renal pelvic adipose tissue. Problems of differential diagnosis are discussed in relation to the use of immunocytochemistry and electron microscopy.

The effect of ionic and nonionic contrast media on the sickling phenomenon.

The effects of an ionic contrast agent (meglumine iothalamate) and a nonionic contrast medium (iopamidol) on the sickling phenomenon were studied in vitro. The findings indicate that, at the same concentration of contrast agent in the blood, iopamidol causes significantly less sickling than meglumine iothalamate. This indicates that nonionic contrast agents are preferable for diagnostic studies in patients with sickle cell anemia.

Xanthogranulomatous pyelonephritis: a reappraisal.

A survey was undertaken of the clinical, radiological, ultrasonic, and pathological features of 80 patients with xanthogranulomatous pyelonephritis (XPN). The condition is a progressive granulomatous reaction to chronic renal inflammation which is often suppurative and usually caused by calculous urinary tract obstruction. The characteristic pathological features are large numbers of foam cells containing lipid, and the presence of inflammatory destruction of neighbouring renal tissue. XPN, which is commoner than generally recognised, may often be diagnosed preoperatively--the patient is usually a middle-aged female who presents with severe toxaemia, tender loin mass, and mild lower urinary tract symptoms. The diagnosis is confirmed by radiology and ultrasonography. Nephrectomy is curative.