Role of cyclic nucleotides in ischemia and reperfusion injury of canine livers

BACKGROUND: In a series of canine liver ischemia experiments, we have shown that amelioration of hepatic injury is achievable by the inhibition of vasoconstriction, cytokine production, platelet aggregation, and neutrophil infiltration. Cyclic adenosine diphosphate (cAMP) was considered to be involved in most of these events. In our study, we tested our hypothesis that augmentation of endogenous cAMP by phosphodiesterase (PDE) 3 inhibitor, amrinone (AM), or adenylate cyclase stimulator, NKH477 (NKH), could attenuate ischemia and reperfusion injury of the liver. METHODS: Thirty-six beagle dogs were used. They were divided into group CT (untreated control), group AM, group NKH, and group CB (treated by both agents). AM or NKH were administered i.v. 1 hr before ischemia (group preAM and group preNKH) or 15 min before reperfusion (pos-AM and postNKH). Combination group animals were treated only before ischemia. Animal survival, hepatic tissue blood flow, liver enzymes, platelet counts, energy metabolism, hepatic cAMP and cyclic guanosine 3',5'-cyclic monophosphate levels, and histopathology were analyzed. RESULTS: Two-week animal survival was significantly improved by pre- or posttreatment with either agent. After reperfusion, hepatic tissue blood flow, liver enzyme release, platelet counts, energy metabolism, tissue cAMP levels, and histological architecture were also ameliorated markedly. Combination of both agents induced severe liver damage and lethal hypotension. AM treatment exhibited more protective effects than NKH, particularly when it was given before ischemia. Interestingly, not only cyclic guanosine 3',5'-cyclic monophosphate, were also restored at higher levels after reperfusion by preischemia treatment. CONCLUSIONS: Administration of amrinone or NKH477 maintained hepatic tissue concentrations of cyclic nucleotides, and attenuated ischemia and reperfusion injury of the liver. Thus, regulation of hepatic tissue cyclic nucleotides is an important alternative for prevention of hepatic damage in liver preservation and surgery.     

The relationship between the severity of a neurological condition and the blood coagulation/fibrinolytic system in patients with spontaneous subarachnoid hemorrhage

In order to examine the relationship between the hemostatic systems and the severity of neurological changes, shortly after spontaneous subarachnoid hemorrhage (SAH) we reviewed 30 patients who had been admitted within 6 hours after the onset of SAH. Peripheral blood samples were obtained within 6 hours of the onset of SAH. There was a significant correlation between increased values of serum antithrombin III, thrombin-antithrombin III complexes, fibrinopeptide B beta 15-42, D-dimers, and the neurological severity of SAH. The data suggest that the activation of the blood coagulation system as well as the fibrinolytic system (especially the secondary fibrinolysis) occurs early in the course of SAH, particularly in patients with a severe neurological condition.     

A case of cerebral syphilitic gumma

A 38-year-old man experienced an intermittent low-grade fever with generalized eruption, followed by rapidly progressive right hemiplegia. Neuroimaging revealed a ring-like enhanced mass in the left premotor cortex surrounded by marked perifocal edema. The syphilitic titer was high both in the serum and in the cerebrospinal fluid. Open biopsy of the lesion revealed the tumor consisted of inflammatory cells associated with plasmacyte infiltration to the perivascular region as well as to the dura, which is consistent with the definition of syphilitic gumma. The abnormalities in neurology and in neuroimaging improved dramatically after antisyphilitic treatment. Difficulties in differentiating a cerebral gumma from other diseases are discussed.     

ET(B) receptor protects the tubulointerstitium in experimental thrombotic microangiopathy

BACKGROUND: The characteristic features of thrombotic microangiopathy (TMA) include glomerular and peritubular capillary endothelial cell injury with thrombus formation and subsequent ischemic tubulointerstitial damage. The endothelin ET(B) receptor has been shown to mediate both endothelial cell proliferation and vasodilation, and we therefore hypothesized that blockade of this receptor might promote more severe injury in this model. METHODS: TMA was induced in recently established transgenic rats that lack expression of ET(B) receptor in the kidney; these animals were compared to control rats with TMA both in the short-term (days 1 and 3) when acute glomerular injury was most manifest, and the long-term (day 17) when glomeruli have recovered but tubulointerstitial injury is still present. Renal damage was assessed by histological analysis and blood urea nitrogen (BUN) measurements. RESULTS: No difference in the TMA model was observed between rats with and without ET(B) receptor on days 1 or 3. At day 17, however, rats without the ET(B) receptor showed more severe tubulointerstitial injury compared with those with ET(B) receptor, which was associated with higher BUN levels. The tubulointerstitial damage was associated with a more severe loss of peritubular capillaries. CONCLUSIONS: These findings suggest that the ET(B) receptor may protect peritubular capillaries under the ischemic insult, and serve a defensive role in the tubulointerstitium induced by renal microvascular injury.     

L-arginine rescues decreased erythropoietin gene expression by stimulating GATA-2 with L-NMMA

BACKGROUND: NG-monomethyl-L-arginine (L-NMMA) decreases the expression of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) and increases the expression of GATA-2 mRNA and levels of GATA-2 binding activity, thereby inhibiting erythropoietin (Epo) promoter activity and causing a decrease in the expression of Epo protein. In the present study, we examined the effect of L-arginine on Epo gene expression in Hep3B cells and BDF1 mice. METHODS: Hep3B cells were incubated with and without different concentrations of L-NMMA and/or l-arginine. Anemic mice were injected with phosphate-buffered saline (PBS) or L-NAME and L-arginine. RESULTS: Incubation with L-NMMA under hypoxic conditions inhibited Epo expression, but this inhibition was recovered by the addition of L-arginine. Hypoxia induced the secretions of NO and cGMP, but the addition of L-NMMA inhibited these inductions, though these inhibitions of NO and cGMP by L-NMMA were recovered by the addition of L-arginine. Hep3B cells transfected with the Epo promoter/enhancer-luciferase gene had Epo promoter activity. This activity was inhibited by L-NMMA, but it could be recovered by the addition of L-arginine. L-NMMA induced the binding activity of GATA-2 under hypoxic conditions. This binding activity was inhibited by the addition of L-arginine. The addition of cGMP inhibited L-NMMA-induced GATA-2 binding activity in a dose-dependent manner. The results of an in vivo mouse assay revealed that L-NAME inhibited the expression of Epo, but this inhibition of Epo expression by L-NAME was rescued by pretreatment with L-arginine.CONCLUSION: L-arginine rescues decreased erythropoietin gene expression by stimulating GATA-2 with NG-monomethyl-L-arginine.     

Imaging of chromosomes at nano-meter scale resolution using scanning near-field optical/atomic force microscopy

Topographic and fluorescent images of whole barley chromosomes stained with YOYO-1 were observed simultaneously by scanning near-field optical/ atomic force microscopy (SNOM/AFM). The chromosome was relatively smooth and flat in the topographic images and no significant difference in height was present between regions of high fluorescent and low fluorescent intensity in the chromosomes. The telomeric region, labeled by fluorescence in situ hybridization (FISH) method, was also observed by SNOM/AFM at high resolution, and fluorescent signals of the telomeric region were clearly defined on the topographic image of chromatin fibers on the chromosome at the nano-meter scale level. Although the telomeric signals were usually visualized as a single fluorescent region at the end of sister chromatids by conventional light microscopy, they were observed separately as two fluorescent regions, less than 100-200 nm distance, using the SNOM/AFM. The SNOM/AFM offers great potential in identifying particular single gene location on chromosomes in the near future.     

Two cases of Swyer-James syndrome

Two cases of Swyer-James syndrome are reported. Case 1; A 25-year-old man was admitted to our hospital to be treated for Mycobacterium avium infection. Chest X-ray film revealed hyperlucency in the right lower lung. High-resolution CT showed a low attenuation area and bronchiectasis in the right lower lobe. He had had two episodes of pneumonia in his childhood. 3D CT scan showed a narrowing of right lower pulmonary arteries. Case 2; A 65-year-old woman was admitted to our hospital with dyspnea on effort. Chest X-ray film revealed hyperlucency in the right lung. Chest CT scan on inspiration and expiration detected air-trapping, which is characteristic of this syndrome. In both cases, the volume of the hyper lucent lung was normal. From these clinical findings, we diagnosed these two cases as Swyer-James syndrome and in this paper described the clinical features and treatment.     

Score tests for detecting excess risks around putative sources

Focused clustering studies examine raised disease risk around prespecified point sources. As statistical methods to detect such clusters, Stone's maximum likelihood ratio test is popular, against the general ordered alternatives and score tests which score each case the reciprocal of the distance from a point source as a surrogate exposure. This paper considers extensions of score tests in that (i) they can allow us to select the best among prespecified parametric exposure functions to avoid multiple testing problems and (ii) they can be applied to a possible situation where the hazardous substance levels have a peak at some distance from a point source. Simulation studies show that the powers of the proposed tests are higher than that of Stone's test over all the alternatives considered. The proposed tests are illustrated with hypothetical data as well as simulated data to be expected in an epidemiological study currently in progress regarding an excess risk of perinatal undesirable outcomes near municipal solid waste incinerators in Japan.