Relation between distribution of DNA synthesizing cells and blood flow and glucose metabolism in Rous sarcoma virus-induced rat brain tumors

The correlations between blood flow or glucose metabolism and distribution of DNA synthesizing cells were simultaneously investigated in the same rat brain tumors using autoradiographic technique and immunoperoxidase stain. Two rat brain tumor strains (A and B) induced by Rous sarcoma virus were used. A suspension of 1 X 10(4) rat brain tumor cells was stereotactically implanted into the right basal ganglia of syngenic Fischer 344/Du Crj rats. The tumor strain A bearing rats died 12.0 +/- 1.8 days and the tumor strain B bearing rats died 17.6 +/- 1.3 days after the tumor implantation. Blood flow and glucose metabolism were measured with 14C-iodoantipyrine and 14C-2-deoxy-D-glucose autoradiography. All rats also received a 1-h i.v. infusion of BrdU, 5-20 mg, at the autoradiographic procedure. The immunoperoxidase staining for BrdU (Avidin Biotin peroxidase complex method) and other conventional stainings were performed in the sections alternating with the autoradiographic sections. BrdU-positive nuclei (S-phase cells) were heterogeneously distributed and labeling index ranged from less than 1% to more than 40% in the tumors. Neoplastic vessels tended to be distributed in the peripheral part of the tumor and were surrounded with S-phase cells in a part of the tumor. The blood flow was heterogeneously distributed in the tumor and the average blood flow reduced to about 50% in the tumor strain A and to about 60% in the tumor strain B, respectively in comparison with contralateral cortex. The distribution of blood flow did not correlate with the distribution of S-phase cells nor the distribution of neoplastic vessels.(ABSTRACT TRUNCATED AT 250 WORDS)     

Metabolism of 99mTc-ethyl cysteinate dimer (99mTc-ECD) in blood--mainly in vitro]

Metabolism of 99mTc-ethyl cysteinate dimer (99mTc-ECD) in blood was studied mainly in vitro. When 99mTc-ECD was mixed with blood taken from 12 subjects, the octanol extraction ratio of ECD (y) decreased rapidly and the octanol extraction ratio-time profile well fitted a monoexponential curve (y = Ae-kt/1000, A, k: constant, t: time after mixing). The k value and hematocrit (Ht) were significantly correlated (k = 0.376Ht-3.27, r = 0.897, p less than 0.001), therefore, it was suggested that the majority of the enzyme which dissolves ECD exists in red blood cells. When ECD was mixed with blood, there were more hydrophilic products of ECD in plasma than those generated by the enzyme in plasma. In vivo input function of 99mTc-ECD was calculated by arterial blood sampling and octanol extraction. The duration of effective input was relatively short, which was attributed to rapid decrease of octanol extraction ratio in vivo.     

Effects of endothelial-cell-derived growth factors on cultured astrocytes.

To clarify the participation of endothelial-cell-derived growth factors (ECDGFs) in astrocytosis, the effects of endothelial-cell-conditioned medium (ECCM) derived either from normotensive rats or spontaneously hypertensive, stroke-prone rats (SHRSPs) on proliferation of C6 cells of an established rat glioma cell line were bioassayed. The ECCM from both strains stimulated proliferation of astrocytes, but the ECCM from SHRSPs showed a higher mitogenic activity for astrocytes than that from normotensive rats. Growth-promoting activity of the ECCM derived from SHRSPs showed an increase that was linear to the conditioning time. These results seem to indicate that endothelial cells produce and release factors that promote the growth of astrocytes. It seems also probable that chronic hypertension causes an increase in production and release of such ECDGFs that correlated with astrocytic proliferation.     

Gorog Thrombosis Test: analysis of factors influencing occlusive thrombus formation.

We used the Gorog Thrombosis Test to analyze the factors influencing the occlusion time, which represents platelet activation and subsequent occlusive thrombus formation, in 132 healthy Japanese volunteers (116 men, 16 women; mean age, 45.0 +/- 12.0 years). The Gorog Thrombosis Test was designed to evaluate platelet aggregation and thrombolytic activity under a high shear stress condition (175 dynes/cm) in a native blood sample in vitro. The mean +/- SD occlusion time was 154.8 +/- 64.7 s (men, 153.4 +/- 64.2 s and women, 165.4 +/- 56.5 s). The occlusion time was inversely correlated with von Willebrand factor ristocetin cofactor activity (VWF:Rco) (r = -0.242, P = 0.0055) and von Willebrand factor antigen (r = -0.230, P = 0.0080). The mean occlusion time in the group with VWF:Rco of at least 170% (137 s) was significantly shorter than that in the group with VWF:Rco less than 170% (156 s, P < 0.05). Platelet counts, other coagulation markers and smoking showed no significant correlations with occlusion time. Red blood cells (r = -0.177, P = 0.0365), hemoglobin (r = -0.191, P = 0.0245) and hematocrit (r = -0.182, P = 0.0329) also showed inverse correlations with the occlusion time. This report is the first to clearly demonstrate the role of von Willebrand factor in the formation of occlusive thrombi in the Gorog Thrombosis Test.     

Diuretic and hypotensive actions of torasemide in hypertensive models of rat

The diuretic and the antihypertensive actions of torasemide were examined in renal and genetic hypertensive rats and compared to the effects of furosemide. Oral administration of torasemide (1 and 3 mg/kg) elicited a dose-dependent increase in the excretion of urine and electrolytes and elevated the urinary Na/K ratio in both renal and genetic hypertensive rats. Torasemide and furosemide had a similar maximum diuretic effect in the normotensive Wistar rat and the spontaneously hypertensive rat (SHR). However, the diuretic activity of furosemide was weaker in the renal hypertensive rat (RHR). Torasemide showed approximately 30 times greater diuretic potency than furosemide. Torasemide and furosemide demonstrated hypotensive action in hypertensive rat models, but not in the normotensive Wistar rat. Especially in the RHR, torasemide exhibited a more potent hypotensive action than furosemide. These results show that the diuretic and antihypertensive activities of torasemide are effective in various rat models of hypertension, while the diuretic activity of furosemide is weak in certain hypertensive rat models. © 1992 Wiley-Liss, Inc.     

Toluene vapor exposure and urinary excretion of hippuric acid among workers in China.

A factory survey was conducted in three provinces in China from 1985 to 1989. The time-weighted average toluene concentrations in breathing zone air were monitored by diffusive sampling, whereas hippuric acid (HA) concentrations in shift-end urine samples were measured by high performance liquid chromatography (HPLC). Exposed workers (456 men and women) were those for whom toluene (up to 548 ppm toluene) accounted for greater than or equal to 90% of total exposure (by vapor concentration in ppm), whereas 517 nonexposed controls were recruited from the same factories or from factories of the same region. There was a linear correlation between the intensity of toluene exposure and HA concentration in the shift-end urine. Comparison of the results with findings in the literature shows that the toluene-induced increase in urinary HA concentration among workers in China is significantly smaller than the published values, whereas HA concentrations in urine samples from nonexposed controls are comparable to the levels previously reported.