Structurally distinct and stage-specific adenylyl cyclase genes play different roles in Dictyostelium development

We have isolated two adenylyl cyclase genes, designated ACA and ACG, from Dictyostelium. The proposed structure for ACA resembles that proposed for mammalian adenylyl cyclases: two large hydrophilic domains and two sets of six transmembrane spans. ACG has a novel structure, reminiscent of the membrane-bound guanylyl cyclases. An aca- mutant, created by gene disruption, has little detectable adenylyl cyclase activity and fails to aggregate, demonstrating that cAMP is required for cell-cell communication. cAMP is not required for motility, chemotaxis, growth, and cell division, which are unaffected. Constitutive expression in aca- cells of either ACA or ACG, which is normally expressed only during germination, restores aggregation and the ability to complete the developmental program. ACA expression restores receptor and guanine nucleotide-regulated adenylyl cyclase activity, while activity in cells expressing ACG is insensitive to these regulators. Although they lack ACA, which has a transporter-like structure, the cells expressing ACG secrete cAMP constitutively.

Acute pseudo-obstruction of the colon following partial splenic artery embolization: report of a case

This is a case of a 45-year-old woman suffering from liver cirrhosis with hypersplenism who received a partial splenic artery embolization with gelfoam pieces. Thrombocytopenia and leukopenia improved immediately after treatment. Marked abdominal distention, metallic bowel sounds and combined small and large bowel distension with air-fluid levels as shown on a plain abdominal X ray were noted on the fifth day after the embolization procedure. Laparotomy was performed. No mechanical obstruction was found during surgery. Acute pseudo-obstruction of the colon (Ogilvie's syndrome) was diagnosed. This condition was considered to be a complication of the partial splenic artery embolization and has not hitherto been reported.

Esterification of fatty acids by bovine intramuscular and subcutaneous adipose tissues

Exogenous fatty acid esterification in intramuscular and subcutaneous adipose tissues from 72-hr fasted or ad libitum fed Angus cattle was investigated. Intramuscular (interfascicular) and subcutaneous adipose tissue snips were obtained from the longissimus dorsi muscle and were incubated with radioisotopically labeled fatty acids (palmitate, stearate, oleate, linoleate or linolenate) at three different concentrations (0.3 mM, 0.6 mM and 2.0 mM) to assess rates of fatty acid incorporation into glycerolipids. Rates of fatty acid esterification in vitro increased with fatty acid concentration in both intramuscular and subcutaneous adipose tissues. For all of the fatty acids investigated, triglycerides were the predominant products (60-85%). Subcutaneous adipose tissue had larger adipocytes and more actively (P less than 0.05) esterified fatty acids, with the exception of palmitate, than intramuscular adipose tissue. The rate of palmitate esterification was not different between tissues, although intramuscular adipose tissue esterified a greater proportion (P less than 0.10) of palmitate as triglyceride (85%) than did subcutaneous adipose tissue (75%). Relative rates of incorporation of fatty acids into lipids in intramuscular and subcutaneous adipose tissues were: palmitate greater than linolenate greater than linoleate greater than stearate. In general, 72-hr fasting did not significantly reduce the rates of fatty acid incorporation in bovine adipose tissues. Results of this study revealed that:i) rates of exogenous fatty acid incorporation into adipose tissue lipids were dependent on the medium fatty acid concentration and adipose tissue depot; and ii) the relative esterification rates of the various fatty acids in vitro did not necessarily reflect the proportion of these fatty acids in bovine adipose tissues.

Binding characteristics of Escherichia coli biotin repressor-operator complex

The genes of the operon bioA.BFCD are transcribed divergently from a single regulatory region between the bioA and, bioB genes. Transcription in both directions is co-repressed by biotinyl-5'-adenylate and the biotin repressor. The multimeric state of the biotin repressor bound to DNA and how it affects transcription have not been fully characterized. Therefore, we isolated the BirA protein from a recombinant strain which overproduced the biotin repressor and studied the repressor-operator binding characteristics through restriction enzyme site protection experiments and the mobility shift assay. We also measured the stoichiometry of the biotin repressor-operator complex directly. The results of restriction enzyme site protection studies are consistent with the postulation that the biotin operator is approx. 40 bp long. Only one retarded DNA band appeared in the mobility shift experiments, suggesting that the repressor-operator binding could be a single step reaction. The repressor-operator binding stoichiometry determination revealed that two repressor monomers may occupy the wild type or half palindromic biotin operator sequences.

The role of aggregation of platelets in pregnancy-induced hypertension: a comprehensive and longitudinal study

Plasma 6-keto-prostaglandin F 1 alpha and thromboxane B2, the metabolites of prostacyclin and thromboxane A2 respectively, were measured in 12 women with pregnancy-induced hypertension, 12 age-matched normotensive pregnant women and 8 non-pregnant women as controls. Pregnancy was divided into 3 stages, namely: 22-27, 28-32 and 33-39 weeks. The concentrations of thromboxane B2 in the plasma of women with pregnancy-induced hypertension was 1.4-1.7 times greater than normotensive pregnant subjects at the same gestational stage, and 2 times higher than controls. Plasma levels of 6-keto-prostaglandin F 1 alpha in normotensive pregnant women was 1.8 times greater than in those with pregnancy-induced hypertension at 28-32 and 33-39 weeks, and was significantly higher than control. The ratio of thromboxane B2 to 6-keto-prostaglandin F 1 alpha was markedly increased in the group of patients with pregnancy-induced hypertension at 28-32 and 33-39 weeks gestation. The ratio of the two metabolites in normotensive patients at each stage of gestation was similar to the control group. The ratio of circulating aggregated platelets in subjects with pregnancy-induced hypertension was significantly lower than in normotensive pregnant subjects at 33-39 weeks, implying increased turnover of platelets in pregnancy-induced hypertension. There was no significant difference in count of platelets, adenosine diphosphate threshold concentration and variables of platelet aggregation induced by adenosine diphosphate among the 3 groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship of platelet specific proteins and other factors to atherosclerosis in various stages of hypertension

There is considerable evidence from previous studies that platelets play an important role in the development and progression of atherosclerosis in hypertension, more so in relation to the stage of hypertension. Seventy one hypertensive patients (WHO stage I: 39, stage II: 23, stage III: 9) aged 19-84 (mean age: 56, 59 and 62 respectively for each stage) and 37 normal controls (aged 22-72 with a mean age of 52) were involved in this study. Hematocrit, beta-thromboglobulin (beta-TG), platelet factor 4 (PF4), beta-TG/PF4 ratio, total cholesterol (TC), low density lipoprotein-C, and triglycerides were higher in the hypertensive group while platelet count, circulating platelet aggregates, and high density lipoprotein-C were higher in the normotensive group. Among the hypertensives, stage III patients showed the highest beta-TG, PF4, beta-TG/PF4 ratio, triglycerides, and stage I with the least elevation. There were no significant differences noted in the ADP or epinephrine-induced platelet aggregation in both the normal and hypertensive patients. Other parameters such as heart rate, serum sodium, potassium, renal and liver function tests, plasma renin activity, aldosterone, fibrinogen thromboxane B2 and 6-Keto-PGF1 alpha, showed no significant differences in both groups. This study clearly showed that beta-TG/PF4 ratio and triglycerides are closely related to the stage of hypertension and are good indicators of in vivo platelet activation in hypertensives which may account for the acceleration of hypertensive vascular complications secondary to atherogenesis.

Studies on the mechanisms of Ni2(+)-induced cell injury: I. Effects of Ni2+ on microtubules

Cytoskeletal perturbations have been associated with exposures to a variety of toxic agents as well as a number of human pathological conditions. We have observed dramatic alterations in the organization of microtubules (MT), a major component of the cytoskeleton, in 3T3 cells exposed to Ni2+. Severe perinuclear bundling and aggregation of MT occurred in both a time- and dose-dependent fashion, and this MT damage was reversible upon removal of Ni2+ from the culture media. To understand the mechanism of the Ni2(+)-induced MT change, we investigated the effect of Ni2+ (0.01 to 3.0 mM) on in vitro tubulin polymerization. Ni2+ at lower concentrations (0.01 to 1.0 mM) had little or no significant effect on the kinetics of MT polymerization. In contrast, in the presence of 1.5 to 2.0 mM Ni2+, a significant promoting effect on both the rate and the final extent of polymerization was observed. However, at Ni2+ concentrations higher than 2.0 mM, such stimulatory effect on the rate and the final extent of tubulin polymerization declined. Furthermore, the promoting effects of Ni2+ on MT polymerization were accompanied by a significant decrease in the lag period. Electron microscopic examination of samples of the polymerization product showed that MT, polymerized in the presence of 2.0 mM Ni2+, appeared more numerous and shorter (1.10 +/- 1.02 microns) than those of control (3.81 +/- 2.29 microns; p less than 0.005). This was probably a direct result of an increase in the number of initiation centers in the presence of Ni2+ as a consequence of the decreased critical concentration (7%, p less than 0.05) necessary for polymerization to occur. Our results suggest that Ni2+ may exert its toxic effect on MT in cultured cells by altering the normal kinetics of MT polymerization.

Characterization of filamentous bacteriophage phi Lf from Xanthomonas campestris pv. campestris

A filamentous phage, phi Lf, which specifically infects Xanthomonas campestris pv. campestris was isolated. The phage particle measured 1,000 (+/- 200) x 8 nm. It formed turbid plaques of about 1 mm in diameter. During multiplication, the progeny virions extruded into the medium without retarding host cell growth. Stocks were stable for 6 months at 4 degrees C and survived treatment at 80 degrees C for 10 min. Treatment with chloroform, ethanol or acetone completely destroyed infectivity; ethyl ether and methanol inactivated 98 to 99% of the phage. SDS-polyacrylamide gel electrophoresis showed a major coat protein band of approximate Mr 4000 whereas an immunoprecipitation test detected the existence of two coat protein species. The phage genome was shown to be a single-stranded DNA molecule. A physical map was constructed and the DNA size was calculated to be 5.9 kb. Cells treated with Tris-HCl containing CaCl2 and polyethylene glycol 6000 were transfected by replicative form DNA at a frequency of 3.4 x 10(3) p.f.u./micrograms.

Detection of dysfunctioning mitral prosthetic regurgitation: transesophageal echocardiography in comparison with transthoracic echocardiography and angiography

Transesophageal echocardiography has been increasingly used in addition to the transthoracic approach. It not only allows an unobstructed window for viewing the left atrium, but also provides high-quality imaging to improve diagnosis of prosthetic valve dysfunction. To determine the value of transesophageal echocardiography in detection of dysfunctioning mitral prosthetic regurgitation, 11 patients clinically suspected of dysfunctioning mitral prosthesis were studies by transthoracic, transesophageal echocardiography and was documented by a left ventricular angiography. There were 7 biological tissue valves and 4 metallic Bjork-Shiley valves. Compared with a left ventricular angiography, the transthoracic approach to 8 patients made an underestimation of the grade of regurgitation. The angiographic grading confirmed the transesophageal approach in all patients except one who was graded as mild regurgitation by left ventricular angiography, moderate regurgitation by transesophageal echocardiography, but no regurgitation by transthoracic echocardiography. Our results indicated that in patients with suspected mitral prosthetic dysfunction, a transesophageal echocardiography is more sensitive than a transthoracic echocardiography in detecting mitral regurgitation.

Effects of exercise and ticlopidine on platelet function and prostanoids in patients with old myocardial infarction

Twenty-eight subjects, 16 with old myocardial infarction (OMI) and a control group of 12, received ticlopidine 250 mg/day for 4 weeks. All subjects underwent the standard Bruce protocol exercise test before and after therapy. Blood was collected from a peripheral vein to study platelet function at pre-exercise (rest), peak exercise (end point), and 6 min post-exercise (recovery). Platelet count, platelet aggregatory response, plasma thromboxane B2 (TXB2), and 6-keto-PGF 1 alpha were measured by Coulter counter, aggregometry, and radioimmunoassay, respectively. The platelet count, aggregatory response (induced by ADP, adrenalin, and collagen) and the plasma concentration of TXB2 and 6-keto-PGF 1 alpha were not significantly affected by exercise in the OMI and control groups. Overall, there were no significant changes in exercise duration, heart rate, and blood pressure in both groups before or after ticlopidine treatment, with some minor exceptions. There were no significant changes in the peripheral blood profiles, the bleeding and coagulation times, the blood chemistry data, and the platelet counts between the groups before or after treatment. There was a significant decrease in collagen- and ADP-induced platelet aggregation in both groups after ticlopidine therapy. Prior to treatment, a higher plasma TXB2 concentration was noted in the OMI group during and after exercise; the difference was no longer statistically significant after ticlopidine therapy when both groups were compared. There was a significant reduction in the TXB2 levels in the OMI group after ticlopidine treatment despite exercise. Before therapy, plasma 6-keto-PGF 1 alpha was significantly elevated in the OMI group before or after exercise but was not statistically significant after ticlopidine treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Nonparasitic hepatic cysts detected in ultrasonographic examination: analysis of 95 cases

Ultrasonography has gained wide use in the diagnosis of hepatic cystic diseases. Ninety cases with nonparasitic hepatic cysts were detected in 4,615 patients who underwent routine abdominal ultrasonography. In this series, hepatic cysts were mostly discovered in men (62.1%), in the age range of 51-70 years (63.1%) and located in the right lobe of the liver (62.1%). Hepatomegaly, abdominal mass, abdominal pain, and jaundice were the common clinical manifestations in patients with symptomatic hepatic cysts (13.7%), especially in cases with larger or multiple cysts. Only 4 patients received invasive management; 2 with ultrasonographic guide aspiration alone, 1 with external drainage, and 1 with alcohol instillation. Complications in this series of liver cysts were noted in 3 patients (3.16%) including infection, portal hypertension and jaundice.

[A preliminary report of the fetal effects of dengue infection in pregnancy]

This Manuscript was read at the Clinical Aspects on Dengue Fever and Dengue Hemorrhagic Fever held at Kaohsiung Medical College, Kaohsiung City, Taiwan, Republic of China, November 13, 1988. There is not enough evidence to prove that the dengue virus will cause teratogenicity, abortion, or intrauterine growth retardation of a fetus during pregnancy. Nine cases of women infected with dengue fever in early pregnancy received amniocentesis (or chorion villi sampling) in the Department of Obstetrics and Gynecology, KMCH. The chromosome analysis revealed that all were normal, and the level of alpha-fetoprotein in amniotic fluids and maternal sera were within normal range. Antibodies to the dengue virus in the dengue infected mother can cross the placenta and transfer to the fetus, which can cause new born infants to develop dengue hemorrhagic fever or dengue shock syndrome easily when they are primarily infected with dengue virus. Anti-dengue activity was found in the lipid component of human milk and colostrum. This suggests that breast feeding will protect the infant from the dengue virus in the endemic area of dengue infection.

Inhibition of ovulation, steroidogenesis and collagenolytic activity in rabbits by sulpiride-induced hyperprolactinaemia

Ovulation induced by hCG in rabbits was reduced significantly (P less than 0.005) by sulpiride-induced hyperprolactinaemia. The pre- and post-ovulatory increases in peripheral and ovarian venous progesterone (but not oestradiol or testosterone) were suppressed in the treated animals. The condition of hyperprolactinaemia also prevented the usual changes in 2,4-dinitrophenyl-Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg-OH peptidase (DNP-peptidase) and alpha-N-benzoyl-DL-Arg-beta-naphthylamide hydrolase (BANA-hydrolase) activities in follicular tissue that had been stimulated by an ovulatory dose of hCG. These results suggest that inhibition of progesterone production and collagenolytic enzyme activity by sulpiride-induced hyperprolactinaemia may be responsible for the ovulatory dysfunction that occurs when a mammal has a high level of circulating prolactin.

Inhibition of human chorionic gonadotropin-induced ovulation and steroidogenesis by short-term hyperprolactinemia in female rabbits

To clarify the possible direct effects of hyperprolactinemia on the ovulatory process, we experimentally established hyperprolactinemia in female rabbits with 4 daily injections of sulpiride (SLP) at different doses and induced ovulation with human chorionic gonadotropin (hCG). Plasma levels of prolactin (PRL) were increased significantly before hCG injection in each SLP-treated group compared with the corresponding values for the controls. The ovulation rates at 14 h after hCG were significantly reduced in the 16 and 24 mg/kg/day SLP-treated groups. An inverse correlation (r = -0.74, P less than 0.001) was found between the ovulation rate and the increasing in plasma PRL measured just prior to hCG injection. The increase in peripheral as well as ovarian venous progesterone and 20 alpha-hydroxypregn-4-en-3-one(20 alpha-OHP) at 4 and 14 h after hCG injection in inhibited ovulation groups was much less than in the control group. However, the estradiol, androstenedione and testosterone concentrations were comparable with the control values. These results indicate that hypersecretion of PRL induced by SLP has a direct effect on ovary by inhibiting follicular rupture induced by hCG and this inhibitory effect was partly due to the suppression of progesterone secretion during the course of ovulation. This may be one of the causes leading to hypogonadism during hyperprolactinemia.

Thyrotropin-releasing hormone and gonadotropin-releasing hormone test to predict effectiveness of bromocriptine therapy in infertile women

Sixty-four infertile women presenting with luteal phase defect, anovulatory cycle, and secondary amenorrhea were compared with 15 normal cycling women with bolus injections of thyrotropin-releasing hormone (TRH) and gonadotropin-releasing hormone (GnRH) before bromocriptine (BCPT) therapy. All of the women had normal baseline prolactin (PRL), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) concentrations. Responses of PRL, LH, and FSH levels were measured. PRL responses in BCPT responders were markedly greater than in controls and nonresponders. A better responder rate to BCPT therapy was observed in patients with apparent (88.9%) or borderline (69.2%) exaggerated responses of PRL to TRH than in normal patients (41.7%). Further, in patients with normal PRL responses, the inappropriately enhanced LH responses were seen in BCPT responders but not in nonresponders. These findings suggest that TRH and GnRH tests are worthwhile in predicting the outcome of BCPT therapy in infertile patients.

Spoilage bacteria in canned foods. II. Sulfide spoilage bacteria in canned mushrooms and a versatile medium for the enumeration of Clostridium nigrificans

Clostridium nigrificans was found to be a spoilage organism of canned mushrooms in Taiwan. A modified beef extract tryptone iron medium, both in broth and agar form, was designed for the detection and recovery of the organisms. A procedure of simple plate counting method of C. nigrificans was established.