Detector sensitivity and accuracy in kidney radionuclide examinations

Conclusions 1. It is possible to obtain more accurate corrections for the geometry (by comparison with existing methods) for radiometry and scintigraphy of the kidneys by means of the proposed method of calculating the detector sensitivity function. 2. Estimates have been made of the differences in the sensitivity functions for the two kidneys, which indicates that radiometric and scintigraphic results can be processed with an accuracy sufficient for clinical purposes without introducing corrections for these differences. All-Union Oncological Science Center, Academy of Medical Sciences of the USSR, Moscow. Translated from Meditsinskaya Tekhnika, No. 4, pp. 19–23, July–August, 1986.     

Design of a polymer drug for serological diagnosis of hepatitis C

A new immunobiological polymer drug has been designed for the serological identification of hepatitis C. The drug is able to reveal specific antibodies in the sera of patients with hepatitis C, meets the current requirements of diagnostic test systems, and shows a high sensitivity and specificity. It is based on polyacroleinic microspheres; the concentrated cell culture biomass of hepatitis C virus (HCV), which contains an adequate set of viral antigens, is used as sensitin. A new diagnosticum is proposed to be used during primary (screening) laboratory studies based on the serological detection of total antibodies to HCV antigens in the volume agglomeration test. The latter is both one of the alternative methods during serological studies and an additional procedure when a set of diagnostic techniques is used.     

Platelets inhibit the induction of nitric oxide synthesis by interleukin-1 beta in vascular smooth muscle cells

We have investigated the role of platelets in regulating the hemostatic and vasomotor properties of vascular smooth muscle. Experiments were performed to examine the effect of the releasate from activated platelets on the production of nitric oxide from interleukin-1 beta (IL- 1 beta)-treated cultured rat aortic smooth muscle cells. Treatment of vascular smooth muscle cells with IL-1 beta resulted in significant accumulation of nitrite in the culture media and in marked elevation of intracellular cyclic guanosine monophosphate (GMP) levels. The releasate from collagen-aggregated platelets blocked the IL-1 beta- mediated production of nitrite and the accumulation of cyclic GMP in smooth muscle cells in a platelet number-dependent manner. In functional assays, the perfusates from columns containing IL-1 beta- treated smooth muscle cells relaxed detector blood vessels without endothelium and the addition of IL-1 beta-treated smooth muscle cells to suspensions of platelets inhibited their thrombin-induced aggregation. The simultaneous treatment of smooth muscle cells with IL- 1 beta and the platelet releasate abolished both the vasorelaxing activities of the perfusates and the inhibition of platelet aggregation. Platelet releasates treated with a neutralizing antibody to platelet-derived growth factor (PDGF) failed to block IL-1 beta- induced nitric oxide production by the smooth muscle cells, as measured by both biochemical and functional assays. The platelet releasate from a patient with gray platelet syndrome likewise failed to block IL-1 beta-induced nitrite release by smooth muscle cells. These results demonstrate that platelets downregulate the production of nitric oxide by IL-1 beta-treated vascular smooth muscle cells through the release of PDGF. This effect may represent a novel mechanism by which platelets regulate vasomotor tone and thrombus formation at sites of vascular injury.     

Statistical Pitfalls in Medical Research

In conducting and reporting of medical research, there are some common pitfalls in using statistical methodology which may result in invalid inferences being made. This paper is aimed to highlight to inexperienced statisticians or non-statistician some of the common statistical pitfalls encountered when using statistics to interpret data in medical research. We also comment on good practices to avoid these pitfalls.     

GROWTH HORMONE ATTENUATES MYOCARDIAL FIBROSIS IN RATS WITH CHRONIC PRESSURE OVERLOAD-INDUCED LEFT VENTRICULAR HYPERTROPHY

• 1 The role of growth hormone (GH) in cardiac remodelling and function in chronic and persistent pressure overload‐induced left ventricular hypertrophy has not been defined. The aim of the present study was to assess short‐term GH treatment on left ventricular function and remodelling in rats with chronic pressure overload‐induced hypertrophy.
• 2 Twenty‐six weeks after induction of ascending aortic stenosis (AAS), rats were treated with daily subcutaneous injections of recombinant human GH (1 mg/kg per day; AAS‐GH group) or saline (AAS‐P group) for 14 days. Sham‐operated animals served as controls. Left ventricular function was assessed by echocardiography before and after GH treatment. Myocardial fibrosis was evaluated by histological analysis.
• 3 Before GH treatment, AAS rats presented similar left ventricular function and structure. Treatment of rats with GH after the AAS procedure did not change bodyweight or heart weight, both of which were higher in the AAS groups than in the controls. After GH treatment, posterior wall shortening velocity (PWSV) was lower in the AAS‐P group than in the control group. However, in the AAS‐GH group, PWSV was between that in the control and AAS‐P groups and did not differ significantly from either group. Fractional collagen (% of total area) was significantly higher in the AAS‐P and AAS‐GH groups compared with control (10.34 ± 1.29, 4.44 ± 1.37 and 1.88 ± 0.88%, respectively; P < 0.05) and was higher still in the AAS‐P group compared with the AAS‐GH group.
• 4 The present study has shown that short‐term administration of GH to rats with chronic pressure overload‐induced left ventricular hypertrophy induces cardioprotection by attenuating myocardial fibrosis.