Determination of plutonium-239 + plutonium-240 and plutonium-241 in environmental samples using low-level liquid scintillation spectrometry

A radiochemical method for the simultaneous determination of 239Pu + 240Pu and 241Pu in environmental samples has been developed. In the course of the analysis a 236Pu tracer was used for estimating the chemical yield of plutonium isotopes. After suitable pre-treatment of the sample, the plutonium nuclides in solution were coprecipitated with iron(III) hydroxide and calcium oxalate and isolated further from impurities and interfering radionuclides by means of anion-exchange chromatography. Plutonium isotopes in the eluate (NH4I-HCI) were converted into nitrate form and then extracted with 20 ml of 5% bis(2-ethylhexyl) hydrogen phosphate extractive cocktail. The final organic solution was measured spectrometrically using an ultra-low-level liquid scintillation spectrometer, Quantulus (LKB, 1220 Wallac). The chemical yields of plutonium range from 25 to 50% for 100 I of sea-water and 30 to 60% for 40 g of dried soil sample. The counting efficiencies are nearly 100% for 239Pu + 240Pu and 48.8% for 241Pu, respectively. The detection limits were estimated to be 0.20 mBq for 239Pu + 240Pu and 2.2 mBq for 241Pu, respectively. The proposed procedure has been tested for the simultaneous determination of 239Pu + 240Pu and 241Pu in sea-water (Irish Sea, North Sea) and soils (Cumbrian coast, UK; Byelorussia, USSR).

[Pathological analysis of renal osteodystrophy in 194 cases]

Renal osteodystrophy is a metabolic bone disease resulted from chronic renal failure. The long-standing alterations in a mineral metabolism generated by renal failure have a profound effect on the skeleton and induce severe systemic metabolic bone disease. Iliac crest biopsies of 194 patients of chronic renal failure were taken and among them 10 cases were examined for Calcium(Ca), phosphorus (p), parathyroid hormone (PTH), 1,25(OH)2D3 and aluminium (Al). The histological bone changes are characterized by development of osteitis fibrosa, increase of bone resorption and the number of osteoclast, increase of osteoid volume (osteoblastic osteoid and acellular osteoid), active remodelling of bone and aluminum deposition in the bone. According to histological appearance, advanced renal bone disease could be subdivided into three groups namely: Secondary hyperparathyroid bone disease (high turnover uremic osteodystrophy), osteomalacia (low turnover uremic osteodystrophy) and mixed uremic osteodystrophy consisting of mild to moderate hyperparathyroid bone disease and defective mineralization. Aluminum-related bone changes might be obtained in various extent in all these groups. Although this classification does not fully represent all the separated entities, and there is also transformation from one form to another, it seems no less significant as a reference for clinical considerations.

[Fungal endocarditis after open-heart surgery. Report of 4 cases]

Four patients with fungal endocarditis after open-heart surgery were confirmed microbiologically. Two of them died, and the other 2 were treated with intravenous administration of miconazole. Clinical symptoms of the disease were similar to those of bacterial endocarditis, but headache and sweating were more predominant. This complication was likely to be found and treated with effective anti-fungi drugs. We suggest that reoperation is the only possible way to cure those with residual shunt or vegetation, and that prevention of postoperative fungal endocarditis is of great importance because of its refractoriness. Measures of preventing fungal endocarditis after open-heart surgery are discussed.

Electronmicroscopic observation on chronic cardiopathy in spontaneous diabetic biobreeding rats

The ultrastructural changes of chronic cardiopathy in diabetic biobreeding rats were observed electronmicroscopically. The thickness of the myocardial capillary basement membrane (CBM) and volume fraction of myofilaments in the myocardium were quantitatively measured with a video interactive display system III (VIDS-III). The effect of metabolic control on chronic diabetic cardiopathy was also investigated.

[Effect of berberine on slow inward ionic current in guinea pig ventricular papillary muscle]

Using a single sucrose gap voltage clamp technique, it was found that berberine hydrochloride (Ber-HCl) had a dose-dependent biphasic effect on Isi of guinea pig papillary muscle. It was more difficult to wash out the inhibitory effect of Ber-HCl on Isi. In the initial stage of the experiment, Ber-HCl 72 mumol/L and 365 mumol/L greatly improved the influx of extracellular Ca2+ and increased the amplitude of Isi. As the drug perfusion was prolonged, however, Ber-HCl dramatically blocked Ca2+ channels and decreased the influx of extracellular Ca2+ consequently, Isi was reduced in amplitude and later disappeared. This experiment further revealed the mechanisms of action of Ber on cardiac contractility and for the treatment of arrhythmias.

The use of nickel-titanium alloy in orthopedic surgery in China

A new biomaterial made of nickel and titanium with its shape-memory characteristics has been manufactured, investigated, and used in Shanghai, China. Since 1981, this biomaterial has been used in 265 cases clinically, among which 71 involved orthopedic surgery. Results are satisfactory without failure in our short-term follow up. This preliminary report of the use of this new biomaterial with the unique characteristic of being able to recover to its original shape with particular transformation temperatures indicates its potential for opening a new field for investigation in surgery. Research to discover appropriate ratios of nickel and titanium for specific usage is underway. The interest and cooperation between the medical and engineering professions may eventually solve the problems through mutual efforts and result in improved shape-memory biomaterials.