Blood Flow and Leukocyte Adhesiveness Are Reduced in the Microcirculation of a Peritoneal Disseminated Colon Carcinoma

Dynamic behavior of leukocytes in the microcirculation of solid tumor tissue was visualized using a fluorescent labeling technique combined with the use of a real-time confocal laser-scanning microscope (CLSM) system. Colon tumor cells (RCN-9) were inoculated into the peritoneal cavity of male Fischer 344 rats. Tumor-free rats were similarly injected with physiological saline (intraperitoneally). Ten days after tumor inoculation, the mesentery was exteriorized and subjected to vital microscopic observation under the CLSM system. Leukocytes were labeled with rhodamine 6G (100 g kg^–1, intravenously), and their behavior within the microvessels (10–30 m in diameter) was analyzed both in the solid tumor tissues and the normal mesentery. Wall shear rate was calculated from the measured values of vessel diameter and erythrocyte flow velocity. In tumor microvasculature of tumor-bearing rats, the centerline erythrocyte velocity (0.73 ± 0.58 mm s^–1, mean±standard deviation) and wall shear rate (210 ± 151 s^–1 were significantly lower than those of the tumor-free rats (1.27 ± 0.83 mm s^–, 344 ± 236 s^–1, respectively). Despite such reduced flow conditions, flux of the rolling leukocytes as well as density of the adhered leukocytes both decreased significantly in tumor microvasculature as compared with normal controls. The methods developed in this work show promise in improving our understanding of tumor biology and pathophysiology. © 1998 Biomedical Engineering Society. PAC98: 8722Fy, 8745Hw, 8745Ft, 8764-t, 4262Be     

Blood flow velocity in the common carotid artery in humans during graded exercise on a treadmill

Cerebral blood volume flow and flow velocity have been reported to increase during dynamic exercise, but whether the two increase in parallel and whether both increases occur as functions of exercise intensity remain unsettled. In this study, blood flow velocity in the common carotid artery was measured using the Doppler ultrasound method in eight healthy male students during graded treadmill exercise. The exercise consisted of stepwise progressive increases and decreases in exercise intensity. The peak intensity corresponded to approximately 85% of maximal oxygen consumption. During this exercise, the heart rate (f _c), mean blood pressure (BP) in the brachial artery and mean blood flow velocity (_cc) in the common carotid artery increased as functions of exercise intensity. At the peak exercise intensity, (f _c), BP and _cc increased by 134.5%, 20.5% and 51.8% over the control levels before exercise (P < 0.01), respectively. The resistance index (RI) and pulsatility index (PI) were determined from the velocity profile and were expected to reflect the distal cerebral blood flow resistance. The RI and PI increased during the graded exercise, but tended to decrease at the highest levels of exercise intensity. As _cc increased with increases in exercise intensity it would be expected that cerebral blood flow would also increase at these higher intensities. It is also suggested that blood flow velocity in the cerebral artery does not proportionately reflect the cerebral blood flow during dynamic exercise, since the cerebral blood flow resistance changes.     

Studies on elementary reactions in the polymerization of 1,2-epoxycyclohexane with organozinc compounds as initiators

1,2-Epoxycyclohexane ( 1 ) was found to behave differently from propylene oxide (PO) in polymerization reactions with organozinc compounds as initiators. A chair-type complex, [Zn-MP]_2,2, is the only compound that shows high catalytic activity for both polymerization of 1 and PO, following an anionic coordination mechanism. On the other hand, the polymerization of 1 with ZnEt₂ or (EtZnOMe)₄ as initiator proceeds according to a cationic mechanism. Cationic polymerization of 1 with ZnEt₂ has two modes of termination reaction resulting in the formation of terminal units containing vinyl ether and allyl ether moieties. The initiation and propagation mechanism of 1 by [Zn-MP]_2;2 is similar to that of PO, but chain transfer reaction takes place in the polymerization of 1 owing to the low stability of the growing chain end. By using [Zn-MP]_2,2 as initiator, it was possible to prepare a block copolymer consisting of an isotactic sequence of monomeric units of PO and a syndiotactic sequence of monomeric units of 1 .     

Imaging mitochondrial redox environment and oxidative stress using a redox-sensitive fluorescent protein.

Redox-sensitive green fluorescent protein (roGFP) is a fluorescent protein in which two cysteines are placed adjacently in the barrel structure. Disulfide formation (oxidation) increases the absorption at short wavelengths (410 nm) at the expense of absorption at longer wavelengths (490 nm). The fluorescence ratio indicates reduction/oxidation, i.e., the redox potential at specific cellular locations.     

Single nucleotide polymorphisms in TNFSF15 confer susceptibility to Crohn's disease

The inflammatory bowel diseases (IBDs), Crohn's disease (CD) and ulcerative colitis, are chronic inflammatory disorders of the digestive tract. The pathogenesis of IBD is complicated, and it is widely accepted that immunologic, environmental and genetic components contribute to its etiology. To identify genetic susceptibility factors in CD, we performed a genome-wide association study in Japanese patients and controls using nearly 80,000 gene-based single nucleotide polymorphism (SNP) markers and investigated the haplotype structure of the candidate locus in Japanese and European patients. We identified highly significant associations (P = 1.71 x 10(-14) with odds ratio of 2.17) of SNPs and haplotypes within the TNFSF15 (the gene encoding tumor necrosis factor superfamily, member 15) genes in Japanese CD patients. The association was confirmed in the study of two European IBD cohorts. Interestingly, a core TNFSF15 haplotype showing association with increased risk to the disease was common in the two ethnic groups. Our results suggest that the genetic variations in the TNFSF15 gene contribute to the susceptibility to IBD in the Japanese and European populations.     

Critical role for chicken Rad17 and Rad9 in the cellular response to DNA damage and stalled DNA replication

The Rad17-replication factor C (Rad17-RFC) and Rad9-Rad1-Hus1 complexes are thought to function in the early phase of cell-cycle checkpoint control as sensors for genome damage and genome replication errors. However, genetic analysis of the functions of these complexes in vertebrates is complicated by the lethality of these gene disruptions in embryonic mouse cells. We disrupted the Rad17 and Rad9 loci by gene targeting in the chicken B lymphocyte line DT40. Rad17-/- and Rad9-/- DT40 cells are viable, and are highly sensitive to UV irradiation, alkylating agents, and DNA replication inhibitors, such as hydroxyurea. We further found that Rad17-/- and Rad9-/- but not ATM-/- cells are defective in S-phase DNA damage checkpoint controls and in the cellular response to stalled DNA replication. These results indicate a critical role for chicken Rad17 and Rad9 in the cellular response to stalled DNA replication and DNA damage.     

Mutation in saposin D domain of sphingolipid activator protein gene causes urinary system defects and cerebellar Purkinje cell degeneration with accumulation of hydroxy fatty acid-containing ceramide in mouse

The sphingolipid activator proteins (saposins A, B, C and D) are small homologous glycoproteins that are encoded by a single gene in tandem within a large precursor protein (prosaposin) and are required for in vivo degradation of some sphingolipids with relatively short carbohydrate chains. Human patients with prosaposin or specific saposin B or C deficiency are known, and prosaposin- and saposin A-deficient mouse lines have been generated. Experimental evidence suggests that saposin D may be a lysosomal acid ceramidase activator. However, no specific saposin D deficiency state is known in any mammalian species. We have generated a specific saposin D(-/-) mouse by introducing a mutation (C509S) into the saposin D domain of the mouse prosaposin gene. Saposin D(-/-) mice developed progressive polyuria at around 2 months and ataxia at around 4 months. Pathologically, the kidney of saposin D(-/-) mice showed renal tubular degeneration and eventual hydronephrosis. In the nervous system, progressive and selective loss of the cerebellar Purkinje cells in a striped pattern was conspicuous, and almost all Purkinje cells disappeared by 12 months. Biochemically, ceramides, particularly those containing hydroxy fatty acids accumulated in the kidney and the brain, most prominently in the cerebellum. These results not only indicate the role of saposin D in in vivo ceramide metabolism, but also suggest possible cytotoxicity of ceramide underlying the cerebellar Purkinje cell and renal tubular cell degeneration.