EFFECTS OF PROSTAGLANDIN E2 ON RENAL FUNCTION AND LUNG LIQUID DYNAMICS IN FOETAL SHEEP

1. The aim of the present study was to determine the effects of prolonged prostaglandin E₂ (PGE₂) administration on the function of the foetal kidneys and lungs in order to gain a greater understanding of the role played by PGE₂ in the control of foetal fluid balance. By studying the effects of PGE2 at two gestational ages, we have also been able to examine the influence of age. 2. We studied the effects of 26 h PGE2 infusion on foetal sheep at a mean (±SEM) of 120.0 ± 0.6 (n= 6) and 139.0 ± 0.8 (n= 4) days of gestation. In both groups, foetal urine production was significantly inhibited throughout the infusion period (P < 0.05). In younger, but not older foetuses, urine production returned to control values within 24 h of ending the infusion (P < 0.05). This PGE2-induced anti-diuresis was associated with foetal hypoxaemia and acidaemia, a reduction in free water clearance and an increase in foetal plasma arginine vasopressin concentrations (P < 0.05). 3. During PGE₂ infusions, foetal breathing movements were inhibited, the effect being greater and more sustained in older foetuses (P < 0.05). 4. Infusions of PGE₂ led to increased lung liquid production at both ages (P < 0.05); lung liquid volumes were reduced in older foetuses (P < 0.05), but were unchanged in younger foetuses. The reduction in lung liquid volume in older foetuses may have been due to inhibition of foetal breathing. 5. We conclude that increased circulating levels of PGE2 have profound effects on foetal renal and lung function which, if sustained, could compromise foetal lung development and perinatal well-being.     

3-甲基芬太尼衍生物立体异构体的 QSAR 研究

用比较分子力场分析(CoMFA)方法研究了3-甲基芬太尼和羟甲芬太尼立体异构体的三维定量构效关系(3D-QSAR)。所得CoMFA-QSAR模型有很好的预测能力(γ²_{cros-validated}=0.716,n_{optimalcomponent}=5,γ²_conventional=0.999,s=0.052,F=1305.1),模型中,被研究化合物的构象可能就是其活性构象。以AM1方法进行量子化学计算,获得上述可能活性构象的结构参数及空间位置参数。基于这些参数,用偏最小二乘法(PLS)获得了被研究化合物的QSAR方程。所得PLS-QSAR模型具有较好的预测能力,并且显示被研究化合物的镇痛活性取决于分子中负电性的哌啶氮原子(N_PA)净电荷以及哌啶氮原子、羰基氧原子、1-β-苯环、4-N-苯环、3-甲基和2′-羟基的空间位置。     

Studies of a familial platelet disorder

At least 22 members of a large kindred have a bleeding tendency resulting from an autosomal dominant disorder of platelet production and function. Phenotypic manifestations include mild to moderate thrombocytopenia, bleeding time prolongation, and abnormal platelet aggregation. Platelet survival time is normal. The platelet disorder in this family appears to differ from known hereditary thrombocytopenic or thrombocytopathic syndromes and may represent a new genetic disease. Six family members reportedly developed hematologic neoplasms: acute monocytic leukemia nine years after treatment for congenital neuroblastoma; lymphosarcoma at age 10 years; myeloid leukemia at age 23 years; acute myelocytic leukemia at age 62 years; leukemia of unknown type at age 48 years; and lymphocytic lymphoma at age 52 years.     

Minimal-exposure transfusion and the committed donor

Autologous blood (collected preoperatively or salvaged intraoperatively) is the safest blood available for transfusion, but its use is not always feasible. It may be possible to decrease a patient's exposure to homologous donors. Pediatric cardiac surgery patients frequently are unable to donate autologous blood preoperatively. Since 1984, attempts have been made to provide parental apheresis platelets and intraoperative blood salvage to such patients to decrease their donor exposure. Further decreases in donor exposure have been the object of a program of collecting from one committed donor all the blood a patient is anticipated to need. This article reviews the experience with 50 pediatric cardiac surgery patients on such a program, in whom the mean decrease in homologous-donor exposure was 57 percent (range, 12-93%). Thirteen of these patients received only homologous blood products from one committed donor, for a mean decrease in homologous-donor exposure of 80 percent (range, 50-93%). A comparison of 12 of these 13 recipients with a matched control group showed no significant difference in red cell transfusion practice but a significant difference in the number of homologous-donor exposures per m2 of body surface area (BSA) (mean donor exposures/m2 of BSA: patients = 1.5, controls = 10.5). The use of one committed donor and autologous blood can provide a minimal-exposure transfusion.     

Gastric tuberculosis: a manifestation of acquired immunodeficiency syndrome

A Haitian man with acquired immunodeficiency syndrome (AIDS), fever, malaise, and diarrhea is described. A computed tomographic (CT) scan showed a retrogastric mass with an associated ulcer. An upper gastrointestinal tract study showed an ulcer with both benign and malignant features. Endoscopy revealed a malignant-appearing ulcer, but cultures and histologic examinations of surgical biopsy specimens indicated gastric tuberculosis. The relationship between tuberculosis and AIDS is discussed.     

Effect of Chlorides Content on the Structure and Properties of Porous Glass Ceramics Obtained from Siliceous Rock

Porous glass-ceramic materials are used in the construction engineering and repair of various objects. The article investigates the method for obtaining porous glass ceramics from siliceous rock with a high calcite content. To obtain samples with an even fine porous structure, a small amount (≤0.386%) of chloride (NaCl, KCl, MgCl₂·6H₂O, CaCl₂) was added to the charge mixture. At the first stage, mechanochemical activation of raw materials was carried out. Siliceous rock, Na₂CO₃ and additives (chlorides) were grinded together in a planetary ball mill. The resulting charge was annealed at a temperature of 850 °C. The influence of the type and amount of chloride on the properties of the charge mixture and glass ceramics has been defined by thermal analysis (TA), X-ray diffraction (XRD), scanning electron microscopy (SEM), etc. The chlorides in the charge mixture decreased the calcite’s decarbonization temperature and had an effect on the macro- and microstructure of the material. As a result, samples of glass ceramics with an even finely porous structure in the form of blocks were obtained. The samples consist of quartz, wollastonite, devitrite, anorthoclase and an amorphous phase. On average, 89–90% of the resulting material consists of with small pores. The apparent density of the samples is in the range of 245–267 kg/m³. Bending and compressive strength reaches 1.75 MPa and 3.8 MPa, respectively. The minimum thermal conductivity of the modified samples is 0.065 W/(m∙°C). The limiting operating temperature is 860 °C, and the minimum thermal shock resistance is 170 °C. The material has a high chemical stability. They can be used as thermal insulation for some types of industrial and civil facilities.     

Uterine leiomyomas reduce the efficacy of assisted reproduction cycles: results of a matched follow-up study

A matched follow-up study design was used to test the hypothesis that pregnancy rates following assisted reproduction procedures do not differ between women with or without intramural or sub-serosal uterine leiomyomas. Women undergoing their first in-vitro fertilization (IVF)- embryo transfer or zygote intra-Fallopian transfer (ZIFT) cycle between January 1993 and June 1995 were included. Cases (women with leiomyomas) were matched 1:1 with the next consecutive control (women without leiomyomas) according to age, number of embryos transferred, embryo grade, and the route of embryo transfer (uterine or Fallopian). Assisted reproduction cycles were performed in an identical manner, independent of the presence or absence of uterine leiomyomas. The main outcomes measured were clinical pregnancy and delivery rates. A total of 182 cycles was evaluated. Of the 91 assisted reproduction cycles performed in the leiomyoma group, there were 34 clinical pregnancies (37%) and 30 deliveries (33%). Of the 91 assisted reproduction cycles in the control group, there were 48 clinical pregnancies (53%) and 44 deliveries (48%). The Mantel-Haenszel estimate of relative risk indicated that the presence of a uterine leiomyoma significantly reduced the chance for a clinical pregnancy or delivery. These findings suggest that leiomyomas are associated with a reduction in the efficacy of assisted reproduction cycles.