FM sonography in diffuse liver disease: prospective assessment and blinded analysis

FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease.     

用于筛选天然产物中脲酶抑制剂的脲酶活性测试方法的建立

抑制幽门螺杆菌产生的脲酶具有治疗胃炎和消化性溃疡的作用。用酚红指示剂和Ｂｅｒｔｈｅｌｏｔ试剂在９６孔培养板上检测重组脲酶活性，其灵敏度指标酚红法每ｍｇ酶蛋白引起的每分钟吸光度变化。△Ａ为６．９，而Ｂｅｒｔｈｅｌｏｔ法每ｍｇ酶蛋白引起的每分钟吸光度比值变化△Ａ为３１３。结果表明用Ｂｅｒｔｈｅｌｏｔ试剂检测重组脲酶活性适宜在９６孔培养板上大规模筛选天然产物中的脲酶抑制剂。     

Isoflurane Anesthesia Attenuates Endothelium-dependent Pulmonary Vasorelaxation by Inhibiting the Synergistic Interaction between Nitric Oxide and Prostacyclin

Background: Endothelium-derived nitric oxide causes vasodilation in part by increasing the dilator activity of other endothelium-derived mediators, including prostacyclin and a K sup +ATP channel-dependent hyperpolarizing factor. Although previous studies have proposed that isoflurane (ISO) depresses endothelium-dependent vasorelaxation by inhibiting endothelium-derived nitric oxide activity, the effects of ISO on the interactions among endothelium-derived dilators have not been characterized. The aim of this study was to determine the mechanisms underlying the inhibitory effect of ISO on endothelium-dependent relaxation in canine pulmonary arteries. Specifically, the goal was to assess the effects of ISO on the individual actions and on the synergistic interactions of these endothelium-derived mediators.

Methods: Canine pulmonary arterial rings were suspended for isometric tension recording. The effects of 1 minimum alveolar concentration ISO (0.4 mM) on vasorelaxation responses to bradykinin, A23187, acetylcholine, cromakalim, and SIN-1 were assessed in phenylephrine-precontracted rings with and without pretreatment with a nitric oxide synthase inhibitor (N sup omega -nitro-L-arginine methyl ester; L-NAME), a cyclooxygenase inhibitor (indomethacin), or a K sup +ATP, channel inhibitor (glybenclamide).

Results: Isofluane attenuated pulmonary vasorelaxation induced by bradykinin, A23187, and cromakalim but had no effect on relaxation induced by acetylcholine or SIN-1. Neither the nitric oxide-mediated nor the prostacyclin-mediated components of relaxation induced by bradykinin and A23187 were altered by ISO. However, ISO abolished the K sup +ATP -mediated component of relaxation and the K sup +ATP -dependent synergistic interaction between nitric oxide and prostacyclin.     

Identification of non-amplifying CYP21 genes when using PCR-based diagnosis of 21-hydroxylase deficiency in congenital adrenal hyperplasia (CAH) affected pedigrees

Steroid 21-hydroxylase deficiency is among the most common inborn errors of metabolism in man. Characterization of mutations in the 21- hydroxylase gene (CYP21) has permitted genetic diagnosis, facilitated by the polymerase chain reaction (PCR). The most common mutation is conversion of an A or C at nt656 to a G in the second intron causing aberrant splicing of mRNA. Homozygosity for nt656G is associated with profoundly deficient adrenal cortisol and aldosterone synthesis, secondary hypersecretion of adrenal androgens, and a severe form of congenital adrenal hyperplasia (CAH) characterized by ambiguous genitalia and/or sodium wasting in newborns. During the course of genetic analysis of CYP21 mutations in CAH families, we and others have noticed a number of relatives genotyped as nt656G homozygotes, yet showing no clinical signs of disease. A number of lines of evidence have led us to propose that the putative asymptomatic nt656G/G individuals are incorrectly typed due to dropout of one haplotype during PCR amplification of CYP21. For prenatal diagnosis, we recommend that microsatellite typing be used as a supplement to CYP21 genotyping in order to resolve ambiguities at nt656.      

Hypoxic dilatation of porcine small coronary arteries: role of endothelium and KATP-channels

1. The aim of the present study was to determine the cellular mechanims and potential mediators involved in hypoxic dilatation of porcine small coronary arteries.
2. Small coronary arteries were isolated from a branch of the left anterior descending artery of porcine hearts, cannulated with glass micropipettes and studied in a perfusion myograph system. At a transmural pressure of 40 mmHg, the arteries had an internal diameter of 167.8±6.6 μm (n=37).
3. In arteries contracted with acetylcholine (ACh), hypoxia (0% O₂, 30 min) caused dilatation (86.9±6.7% relaxation, n=6) in vessels with endothelium but constriction in endothelium-denuded vessels.
4. Hypoxic vasodilatation occurring in arteries with endothelium was abolished by the K_ATP channel inhibitor, glibenclamide (0.44 μM), but was not affected by inhibition of nitric oxide synthase (L-NAME, 44 μM) or cyclo-oxygenase (indomethacin, 4.4 μM).
5. Bradykinin evoked endothelium-dependent relaxation that was inhibited by L-NAME (44 μM) but not glibenclamide 0.44 μM). Cromakalim (0.1–0.3 μM), a K_ATP channel opener, caused relaxation that was inhibited by glibenclamide, but was not affected by L-NAME (44 μM) and/or indomethacin (4.4 μM).
6. Endothelium-removal inhibited vasodilatation evoked by cromakalim, but increased vasodilator responses to the NO donor, SIN-1 (10⁻⁸ to 10⁻⁵ M).
7. These results indicate that hypoxia acted directly on vascular smooth muscle of small coronary arteries to cause contraction. However, this effect was overwhelmed by endothelium-dependent relaxation in response to hypoxia. This relaxation was most likely mediated by release of an endothelium-derived factor, distinct from nitric oxide or prostacyclin, that activated smooth muscle K_ATP-channels.

     

Involvement of deprivation and environmental lead in neural tube defects: a matched case-control study

OBJECTIVE: To analyse the prevalence of neural tube defects in small geographical areas and seek to explain any spatial variations with reference to environmental lead and deprivation. SETTING: The Fylde of Lancashire in the north west of England. DESIGN: Cases were ascertained as part of a prospective survey of major congenital malformations in babies born in the Fylde to residents there between 1957 and 1981. A matched case-control analysis used infants with cardiovascular system, alimentary tract, and urinary system malformations as controls. Conditional logistic regression was used to assess the effects of more than 10 micrograms/l lead in drinking water and the Townsend deprivation score. RESULTS: The prevalence of neural tube defects in 1957-73 was higher in Blackpool, Fleetwood, and North Fylde, whereas the three control groups showed no significant spatial variation. In 1957-81 mothers living in electoral wards with either a higher proportion of houses with more than 10 micrograms/l lead in the water or a higher deprivation score had a greater risk of having a baby with a neural tube defect. For spina bifida and cranium bifidum alone, this was also true. For anencephaly, deprivation was less important although the effect of lead was still seen. In some neural tube defects, lead may act independently of other possible factors associated with deprivation. It seemed unlikely that lead levels changed significantly during the survey. The percentage of houses with 10 micrograms/l or more of lead in the water in 1984-5 was similar to that found in Great Britain 10 years previously. CONCLUSION: There is evidence to suggest that lead is one cause of neural tube defects, especially anencephaly. This could link the known preventive actions of hard water and folic acid. Calcium is a toxicological antagonist of lead. One cause of a deficiency of folic acid is impaired absorption secondary to zinc deficiency, which may be produced or exacerbated by lead.     

Effects of dietary fat and a vegetable-fruit mixture on the development of intestinal neoplasia in the ApcMin mouse

The variation in colorectal cancer (CRC) incidence worldwide strongly suggests a role for dietary influences. Based on epidemiological data, protective effects of vegetables and fruit intake on CRC are widely claimed, while other data indicate a possible increased CRC risk from (higher) dietary fat intake. Therefore, we have investigated single and interactive effects of dietary fat and a vegetable-fruit mixture (VFM) in the ApcMin mouse, a mouse model for multiple intestinal neoplasia. In this study, four different diets (A-D) were compared, which were either low in fat (20% energy diets A/B) or high in fat (40% energy diets C/D). In addition, 19.5% (wt/wt) of the carbohydrates in diets B and D were replaced by a freeze-dried VFM. The diets were balanced so that they only differed among each other in fat/carbohydrate content and the presence of specific plant-constituents. Because the initiation of intestinal tumors in ApcMin mice occurs relatively early in life, exposure to the diets was started in utero. Without the addition of VFM, mice maintained at a high-fat diet did not develop significantly higher numbers of small or large intestinal adenomas than mice maintained at a low-fat diet. VFM added to a low-fat diet significantly lowered multiplicity of small intestinal polyps (from 16.2 to 10.2/mouse, 15 animals/group), but not of colon tumors in male ApcMin mice only. Strikingly, addition of VFM to female mice maintained on a low-fat diet and to both sexes maintained on a high-fat diet significantly enhanced intestinal polyp multiplicity (from 16.5 to 26.7 polyps/mouse). In conclusion, our results indicate that neither a lower fat intake nor consumption of VFM included in a high-fat diet decreases the development of polyps in mice genetically predisposed to intestinal tumor development.      

Natural course of the impairment of endothelium-dependent relaxations after balloon endothelium removal in porcine coronary arteries. Possible dysfunction of a pertussis toxin-sensitive G protein

The purposes of the present study were to examine the natural course of the impairment of endothelium-dependent relaxations during a regeneration and tissue repair process after balloon endothelium removal and to elucidate the cellular mechanism(s) underlying it. Twenty-three male Yorkshire pigs underwent balloon endothelium removal along the proximal portion of either the left anterior descending or circumflex coronary artery and were then maintained on a regular chow for 4, 8, 16, or 24 weeks. Endothelium-dependent responses were examined in vitro in rings taken from the control and previously denuded arteries studied in parallel. Morphometric analysis revealed that intimal thickening developed only at the previously denuded area. In the previously denuded arteries with regenerated endothelium, the endothelium-dependent relaxations to UK 14304 (a selective alpha 2-adrenergic agonist), serotonin, and aggregating platelets were impaired 4 weeks after endothelium removal and remained so throughout the study. The endothelium-dependent relaxations to thrombin and adenosine diphosphate became depressed 8 weeks after endothelium removal and those to bradykinin became depressed 16 weeks after endothelium removal, while those to the calcium ionophore A23187 were maintained throughout the study. Endothelium-dependent relaxations to all vasoactive agents were unaltered in the control arteries. In the control arteries, pertussis toxin, an inhibitor of certain G proteins, markedly inhibited the endothelium-dependent relaxations to UK 14304 and serotonin and partially inhibited those to thrombin and aggregating platelets. The responses inhibited by the toxin in control arteries were significantly reduced in the reduced in the previously denuded arteries with regenerated endothelium. The inhibitory effect of pertussis toxin was markedly reduced in those arteries with regenerated endothelium. In quiescent rings, the presence of normal endothelium inhibited the contractions caused by serotonin and aggregating platelets; this endothelium-dependent depression was markedly impaired in the previously denuded arteries throughout the study. Direct relaxation of the coronary smooth muscle to nitric oxide or sodium nitroprusside or direct contraction to KCl or serotonin were comparable between the control and previously denuded arteries. These experiments indicate that endothelium-dependent relaxations progressively worsen after regeneration of the endothelium and that the dysfunction of a pertussis toxin-sensitive G protein partly account for the endothelial dysfunction in the chronic regenerated state.