Effects of protein leakage on online monitoring of ultraviolet absorbance in spent dialysate

Recently, dialysis dose during hemodialysis treatment has been monitored by measuring the concentration of urea-like solutes such as uric acid in spent dialysate using near-ultraviolet (UV) light. The measured absorbance has been shown to have a good correlation with the time course of urea level even if the absorbance does not result from urea. However, the spent dialysate includes various solutes such as uric acid and albumin as well as unknown solutes that also absorb UV light. The effects of these solutes on monitored absorbance values are not clear. In this study, we evaluated the effect of protein leakage on data from the UV monitoring of spent dialysate. Albumin leakage in the earlier stage of the treatment may result in an increase in absorbance greater than the expected value. As a result, there is a possibility that the dialysis dose is overestimated. On the other hand, the quantity of albumin leakage could be estimated by a spent dialysate monitoring technique combined with a protein removal process.     

Effects of surrounding conditions on boundary and internal echoes of simulated mass lesions: A phantom study

Ultrasonography has been widely used in the maxillofacial region because of the ability to demonstrate pathological conditions in real time without radiation exposure. However, echo patterns of mass lesions vary with the surrounding tissue conditions. To examine the effects of the various surrounding conditions on depiction of such lesions on echograms, we constructed a model, an echo phantom consisting of an agar object, with or without scattering (methylcellulose) or absorptive (barium sulfate) material, and a corresponding surrounding medium. The object's boundary clarity decreased with increasing concentration of either the surrounding scattering or absorptive media, whereas the internal echo intensity of the object also decreased only with increasing concentration of the surrounding absorptive medium. The object with absorptive material produced peripheral echoes at the border. These results suggest that care should be taken when boundary echoes are evaluated as echo signs of lesions.     

In situ hybridization histochemistry for the kidney diseases]

Crucial points of in situ hybridization methods were pointed out for study on the kidney diseases at molecular level. As examples of in situ hybridization study on kidney, we introduced two cases: 1) expression of the hepatocyte growth factor gene during renal regeneration after unilateral nephrectomy, and 2) induction of the metallothionein gene expression by ischemic acute renal failure. We proposed an idea to establish a probe bank for the in situ hybridization study.     

Radiofrequency hyperthermia with successive monitoring of its effects on tumors using NMR spectroscopy.

Radiofrequency (rf) hyperthermia was generated on rat glioma inoculated s.c. in CD Fisher rats by applying the rf pulse using the surface coil in the NMR spectrometer, and the effect was monitored successively in the same spectrometer by measuring 31P NMR spectra and 1H NMR images. In the 31P NMR spectrum at the preirradiation stage, nucleoside triphosphate peaks and a phosphomonoester peak were high and a Pi peak was low. After a rf pulse at a power of 5 W was applied continuously for 60 min, the nucleoside triphosphate peaks decreased and the Pi peak increased immediately, resulting finally in a dominant Pi peak pattern within 30 min in all 10 cases examined. These spectral changes occurred much earlier than the histological changes and lasted for at least 7 days. By the 1H NMR imaging, the necrotic region was detected as a high-intensity lesion in spin echo and inversion recovery images 2 days after the irradiation. There were no changes either in the spectrum or in 1H NMR images in any of 8 cases after irradiation with a rf pulse of less than 3 W. Thus, we could generate rf hyperthermia with the NMR spectrometer and the effects were monitored sensitively with the same spectrometer. It can be concluded that the NMR device can be used not only for diagnosis but also as a therapeutic tool.     

Comparative utilization of a crystalline amino acid diet and a methionine-fortified casein diet by young rats and mice

A recently developed chemically defined diet containing crystalline amino acids (16% of the diet, 14.4% crude protein equivalent) as the sole source of nitrogen was compared to a methionine-fortified case in diet (20% crude protein) when fed in dry form to weanling rats and mice. Rate and efficiency of weight gain were similar for both diets in rats as well as mice. This finding suggests that the crystalline amino acid diet results in near maximal growth performance and thus supports its efficacy in future nutrition research endeavors.