Clinical implications and factors related to left atrial spontaneous echo contrast in chronic nonvalvular atrial fibrillation

The mechanisms leading to formation of spontaneous echo contrast (SEC), a smoke-like echo on echocardiography, are still controversial. To further explore the clinical implications and factors related to SEC formation, the correlation among echocardiographic variables, hematologic parameters or platelet aggregability, and the occurrence of SEC was studied in 119 patients with chronic nonvalvular atrial fibrillation. There were 75 men and 44 women with a mean age of 65 +/- 10 years (range 38-88). Left atrial SEC was detected in 39 patients (33%) by transesophageal echocardiography. Patients with history of systemic embolism were more frequently found to have left atrial SEC and left atrial thrombus by univariate analysis. Multivariate analysis showed that left atrial SEC (p < 0.001) was the only independent predictor of history of systemic embolism. Age, sex, left atrial or left ventricular dimension, left ventricular ejection fraction, antiplatelet or anticoagulant therapy and the percentage of lone atrial fibrillation were not significantly different between patients with and without left atrial SEC. Among the hematologic parameters, higher hematocrit was found in patients with left atrial SEC, while white blood cell and platelet counts were comparable in both groups. Platelet aggregability with different concentrations of inducers, adenosine diphosphate and collagen, was evaluated by the turbidimetric method in 15 patients with left atrial SEC and in 42 patients without left atrial SEC who were not receiving antiplatelet or anticoagulant therapy. No significant difference was found in platelet aggregability using four inducer concentrations between two groups of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of insulin-like growth factor-I (IGF-I) and IGF-binding protein 1 gene transcription by hormones and provision of amino acids in rat hepatocytes

Synthesis of insulin-like growth factor-I (IGF-I) and IGF binding protein-1 (IGFBP-1) is altered in diabetes and malnutrition, but underlying processes are poorly understood. To study molecular mechanisms, we examined regulation of IGF-I and IGFBP-1 gene transcription in primary cultures of rat hepatocytes. Transcription of the IGF-I and IGFBP-1 genes was measured as incorporation of [alpha-32P]UTP into preinitiated message in isolated nuclei. IGFBP-1 gene transcription was not sensitive to reduction in amino acid concentration from 5x to 0.5x rat arterial plasma levels. However, IGF-I gene transcription fell 60-70% in response to reduced provision of amino acids. Culture with 10(-9) M insulin lowered IGFBP-1 gene transcription 50% below control levels (10-11 M) but did not affect IGF-I gene transcription; 10(-6) M insulin raised IGF-I gene transcription 2-fold. After an acute reduction in insulin concentration, IGFBP-1 transcription began to rise within 30 min, but IGF-I gene transcription was unchanged over 120 min. Similarly, 3-6 h were required for stimulation of IGF-I gene transcription by insulin, but a 40% decrease in IGFBP-1 gene transcription could be detected within 15 min after adding 10(-6) M insulin, and suppression of IGFBP-1 transcription by insulin was unaffected by the presence of cycloheximide. Effects of insulin on IGFBP-1 gene transcription were not mimicked or antagonized by phorbol ester.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma endothelin level changes during hemorrhagic shock

The purpose of this study was to analyze changes in plasma endothelin-1 levels during hemorrhagic shock. Thirty-two mongrel dogs were divided into four equal groups with group I as the controls and groups II through IV as experimental groups. The dogs in the experimental groups underwent hemorrhagic procedures. The mean blood pressure was kept at the level of 65 mm Hg in group II, 50 mm Hg in group III, and 40 mm Hg in group IV. Blood samples were collected from each dog under the following conditions: (1) after induction of anesthesia, when the animals were hemodynamically stable, before the start of shock; (2) 1 minute after the mean arterial pressure dropped to the level designed for each group (shock 1); (3) 15 minutes after shock 1; (4) 30 minutes after shock 1; (5) 1 hour after shock 1; (6) 2 hours after shock 1; (7) 4 hours after shock 1; and (8) 8 hours after shock 1. Plasma endothelin-1 levels both in arterial and venous blood were analyzed in each dog. The results showed that (1) arterial endothelin-1 concentrations were considerably lower than venous concentrations at the baseline level; (2) after the shock-1 point, plasma endothelin-1 concentrations increased, first markedly and then evenly throughout the oligemic period; (3) elevation of plasma endothelin-1 levels was significantly linearly correlated with the amount of blood loss at the time of 2 hours after shock and thereafter; (4) the arterial/venous ratio of plasma endothelin-1 levels during the oligemic period was higher than that in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

[Midazolam and Meperidine for colonoscopy]

We studied the sedative, analgesic and amnesic effects of intravenous midazolam and meperidine for colonoscopy, and also compared patient's satisfaction, changes of vital signs, safety and complications with intramuscular meperidine during the colonoscopy. Two hundred and ninety-nine patients undergoing physical check-up were randomized to receive intramuscular meperidine 50 mg and Hyoscine-N-Butylbromide (buscopan) 20 mg (Group IM-MB, n = 57) or intravenous midazolam 0.05 mg/kg, meperidine 1 mg/kg and buscopan 20 mg (Group IV-MMB, n = 242) before colonoscopy. All patients were closely observed and arterial oxygen saturations (SaO2) were monitored with pulse oximeter in Group IV-MMB. The demographic data of both groups were similar. There were significantly more severe pain responses (grimacing, moaning, shouting for pain, abdominal rigidity and body moving during colonoscopy) in Group IM-MB (51%) than in Group IV-MMB (13%) (p < 0.01). In immediate procedure recall after recovery from medications, 39% of Group IM-MB remembered severe pain during colonoscopy and only 3% of Group IV-MMB did (p < 0.01). 92% of Group IV-MMB who felt satisfactory with the medications were significantly higher than 21% in Group IM-MB (p < 0.01). Both groups significantly increased in heart rate after the injection of medications (p < 0.01). Group IM-MB increased 15 +/- 18% and Group IV-MMB 61 +/- 28% with significant difference between groups (p < 0.01). This might be caused by meperidine, buscopan, and relative hypovolemia of patients. There were significant decreases in SaO2 in Group IV-MMB, mean 4.5 +/- 1.7% (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of pH on endothelin-1 secretion of aortic strips

In this study, aortic strips taken from mongrel dogs were used as experimental material. After preparation, the aortic strips were incubated in a designed control medium or an experimental medium (adding thrombin or epinephrine to the control medium). The pH value of each incubation medium mentioned above was adjusted with HCl or NaOH to a level of 8.0, 7.4, 7.0 and 6.6, respectively, in order to investigate the influence of medium acidity on the production of endothelin-1 from endothelial cells using aortic strips. After a designated time duration (one hour, three hours, six hours and 12 hours, respectively), the incubation media were collected for assay of endothelin-1. The results demonstrated that the endothelin-1 level of the incubation medium was elevated when: 1) the incubation time was lengthened; 2) the incubation medium was more acidic; 3) the aortic strips were incubated with a stimulant, such as thrombin and epinephrine; and 4) the endothelial cells on the aortic strips were intact. This indicates that the secretion of endothelin-1 is: 1) time-dependent, 2) pH-dependent, 3) stimulant-dependent and 4) endothelium-dependent.

Plasma endothelin levels and surgically correctable pulmonary hypertension

To know the changes in plasma endothelin of patients with pulmonary hypertension, we studied 32 patients with valvular heart disease. Among them, 22 patients had pulmonary hypertension (group I) and 10 had pulmonary arterial pressures in the normal range (group II). Plasma endothelin-1 concentrations of the patients in group I were significantly greater than those of the patients in group II (p < 0.05). No significant difference in plasma endothelin-3 concentrations existed between the two groups. Cardiac output and pulmonary capillary wedge pressure had a linear correlation with plasma endothelin-1 levels. There was also a significant correlation between plasma endothelin-1 levels and hemodynamic indicators of severity of pulmonary hypertension, such as mean pulmonary arterial pressure and pulmonary vascular resistance (p < 0.05). All patients in this study underwent surgical procedures for the correction of valvular lesions. All patients in group I showed a decrease in pulmonary arterial pressures, and their plasma endothelin-1 levels decreased from 3.84 +/- 0.20 pg/mL to 1.66 +/- 0.07 pg/mL (p < 0.05), whereas the plasma endothelin-3 levels had only slight variation from 0.64 +/- 0.11 pg/mL to 0.75 +/- 0.06 pg/mL (p > 0.05) between the preoperative and the postoperative stages. The results demonstrated that plasma endothelin-1 rather than endothelin-3 had a role in pulmonary hypertension. Several pieces of evidence pointed out that endothelin-1 functioned as a reactive mediator during vasoconstriction in the case of pulmonary hypertension rather than as a triggering factor of pulmonary hypertension.

[Photodegradation assay method of nifedipine and its application to studies on percutaneous absorption]

A new method of analysis for low concentrations nifedipine was developed according to the principle of a photodegradation analytical method that has been reported by the authors previously, and was used to study percutaneous absorption. The absorbance of sample solution was measured before and after light irradiation at 237 nm for 2 h. In this method, calibration graph was linear in the range of 1-20 micrograms/ml for delta A237. The average recovery for nifedipine was 98.80%. No interference from propylene glycol, azone, m-nifedipine, nitrendipine, verapamil and propranolol was observed. It is shown that azone can promote markedly percutaneous absorption of nifedipine.

The role of endothelin-1 during ischemia-reperfusion injury

In order to investigate the role of endothelin-1 during ischemia-reperfusion injury, 80 adult male Wistar rats were subjected to three hours of ischemia and one hour of reperfusion. Animals were evenly divided into eight groups. The rats in group 1 served as the normal control group, while the rats in group 2 received an intravenous infusion of endothelin-1 in a dosage of 0.5 ng/kg/min, group 3 in a dosage of 5 ng/kg/min, and group 4 in a dosage of 50 ng/kg/min. The rats in group 5 were infused with angiotensin II (10 ng/kg/min). The rats in group 6 received an intravenous infusion of 10,000 units of superoxide dismutase and 10,000 units of catalase. Group 7 rats were infused with endothelin-1 (50 ng/kg/min), superoxide dismutase (10,000 units), and catalase (10,000 units). Group 8 rats received an infusion of angiotensin II (10 ng/kg/min), superoxide dismutase (10,000 units) and catalase (10,000 units). The infusions were given during the reperfusion period. After one hour of reperfusion, the gastrocnemius and soleus muscles of the experimental animals were excised and assayed for ischemia-reperfusion injury by measuring triphenyltetrazolium chloride (TTC) reduction. The results showed that the limb activity of the ischemic extremity was 40.33 +/- 2.75% in group 1, 41.62 +/- 4.08% in group 2, 14.42 +/- 3.14% in group 3, 4.43 +/- 1.05% in group 4, 23.81 +/- 3.51% in group 5, 57.23 +/- 4.52% in group 6, 31.79 42- 3.63% in group 7, and 27.39 +/- 3.95% in group 8. Endothelin-1 reduced the limb activity in a dose-dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenovirus VARNA1 gene B block promoter element sequences required for transcription and for interaction with transcription factors

We constructed mutants with a deletion of either half of the 18 base-pair B block palindrome in the VARNA1 gene, mutants with different intra-palindromic spacings, a complete set of mutants with single base substitutions, and mutants with double and triple base substitutions in the palindrome. The transcription efficiencies of these mutants were determined in human KB cell-free cytoplasmic S100 extracts. The relative competing strength of each mutant, as determined by a sequential competition experiment, was used to assess each mutant's ability to sequester factors into formation of a stable preinitiation complex. The ability of each mutant to assemble transcriptionally active preinitiation complexes was also determined by direct transcription of the isolated complexes. Finally, the ability of each mutant to interact with the transcription factor(s) TFIIIC and form a distinct gel-resolved complex was also determined. From the results of the above assays, we concluded that the two seemingly identical halves of the palindrome did not contribute equally to transcription, or to assembly of the functional preinitiation complex, nor to interaction with TFIIIC. The anterior half (B1) of the B block palindrome, which is proximal to the A block promoter element, played a stronger role in transcription and in assembly of the functional preinitiation complex than the posterior half (B2) of the palindrome. Consistent with this observation, the point mutations in four base-pairs, GTTC, from +60 to +63 in the anterior half of the B block palindrome, has the most severe effect on transcription. In contrast, we showed that the central sequence and the posterior half (B2) played a stronger role than the anterior half (B1) of the B block palindrome in the interaction of the promoter with TFIIIC. This was corroborated by the observation that base substitutions in the central four base-pair sequence of the palindrome, TCGA, from +62 to +65, had the most severe effect on interaction with TFIIIC, and that mutations in most of the sequences in the posterior half of the B block palindrome had more drastic effects than mutations in the anterior half of the palindrome in this interaction. Furthermore, the spacing between the two halves of the B block palindrome had a drastic effect on the overall transcription efficiency and the interaction of the promoter with TFIIIC, suggesting that the interaction between the two halves of the B block palindrome is not only essential, but also synergistic for the interaction with TFIIIC as well as the assembly of a transcriptionally active preinitiation complex and efficient transcription.

Effects of fibrin glue on hemostasis

In order to decrease complications following incomplete hemostasis, we tried to make a safe, efficient and highly concentrated fibrin glue by thawing single-donor fresh frozen plasma. Using a unique animal model, in which arterial bleeding was created, fibrin glue and some related hemostatic agents were tested to evaluate their hemostatic effectiveness. The results demonstrated that: 1) the concomitant use of cryoprecipitate-thrombin tissue glue with adjuvant (aprotinin or calcium chloride) had a better hemostatic effect than the use of cryoprecipitate-thrombin tissue glue alone (p < 0.05); 2) impregnation of fibrin glue with a suitable vehicle was advisable to accelerate the coagulation plug formation and to enhance the mechanical strength of the adhesive plug; 3) Gelform, used as a vehicle to hold the fibrin glue, had a more efficient hemostatic effect than gauze, collagen fleece and Surgicel (p < 0.05); 4) systemic heparinization attenuated the effectiveness of the hemostatic agents and aggravated the bleeding problem, but a low hematocrit level did not; 5) fibrin glue had its own limitations, especially under systemic heparinization, on hemostatic effectiveness in a high-pressure system. Understanding the characteristics of fibrin glue, as mentioned above, definitely improved the hemostatic effectiveness of the glue, especially after failure of the usual methods of controlling bleeding.

[Patient-controlled intravenous versus epidural analgesia after major joint replacement]

The analgesic efficacy, side effects, and satisfaction of patient-controlled analgesia (PCA) with intravenous and epidural morphine for postoperative pain were evaluated in this study. Twenty patients undergoing major joint replacement surgery were randomly allocated to intravenous PCA (IPCA) group or epidural PCA (EPCA) group. All patients had a standardized balanced anesthesia, and an epidural catheter was introduced after the operation in EPCA group. Postoperative pain relief was evaluated with verbal pain scale. The result showed that pain intensity and pain relief were similar in either group without significant difference (p greater than 0.05). Morphine consumption in IPCA group was 1.72 +/- 0.30 mg/h in the postoperative 0 - 12 h and 1.14 +/- 0.44 mg/h in 12 - 24 h. In EPCA group, relatively low doses of morphine were used, i.e., 0.20 +/- 0.07 mg/h in the postoperative 0 - 12 h and 0.17 +/- 0.07 mg/h in 12 - 24 h. Both groups showed an "incomplete" but satisfactory analgesia with relatively low doses of morphine. The "equianalgesic dose ratio" of IPCA to EPCA with morphine was approximately 8.5:1. Sedation was minimal in both groups. No respiratory depression developed in all patients. Nausea and vomiting were the most prominent side effects which might limit the usefulness of PCA. The incidence was 5 out of 10 patients in IPCA group and 4 out of 10 patients in EPCA group, despite under the treatment of droperidol (15 micrograms/kg, iv, prn) for most of the patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of hepatic insulin-like growth factor-I and insulin-like growth factor-binding protein-1 genes is transcriptionally regulated in streptozotocin-diabetic rats

Insulin-like growth factor-I (IGF-I) and IGF-binding protein-1 (BP-1) are critical cell regulators, with regulation and action in endocrine, paracrine, and autocrine modes. Although IGF-I and BP-1 are thought to be modulated mainly at the level of synthesis, underlying molecular mechanisms are poorly understood. To examine regulation by insulin, we used run-on assays to measure IGF-I and BP-1 gene transcription rates in nuclei isolated from the livers of normal and diabetic rats. Streptozotocin (STZ)-treated rats exhibited 20-25% weight loss, a 2.5- to 3-fold increase in serum glucose, and a 50-60% fall in circulating IGF-I levels (all P less than 0.001). Diabetic animals also had a 45% reduction in hepatic IGF-I mRNA and over 400% increases in BP-1 mRNA (both P less than 0.005); all parameters were restored toward normal after treatment with insulin. Metabolically responsive IGF-I gene transcription was evaluated effectively with a 3.2-kilobase BglII/EcoRI genomic probe located down-stream from all initiation sites in exon 1, while BP-1 gene transcription was studied with a cDNA probe. Animals treated with 144 mg/kg STZ exhibited 50-97% decreases in IGF-I gene transcription (P less than 0.05), while insulin treatment raised IGF-I gene transcription to control levels (P less than 0.02). IGF-I gene transcription appeared to be more sensitive to metabolic status than IGF-I mRNA levels, resulting in a modest correlation between transcription rates and mRNA levels (r = 0.68; P less than 0.001). In contrast, changes in BP-1 mRNA and gene transcription appeared to be exquisitely sensitive to metabolic status.(ABSTRACT TRUNCATED AT 250 WORDS)

[Determination of m-nifedipine and its pharmacokinetic study in rabbits by high-pressure liquid chromatography]

A high-pressure liquid chromatographic method was developed for determination of m-nifedipine in plasma using a chemical bonded C-18 phase column (YWG-C18 10 microns, made in China) with nitrendipine as internal standard. To increase life of the YWG-C18 column a mixture of methanol and 5 mmol.L-1 phosphate buffer (70:30 vol/vol) was selected as mobile phase with a flow rate of 0.8 ml.min-1. The method was sensitive to m-nifedipine 3 ng.ml-1 plasma and the standard curve was linear from 10 to 1000 ng.ml-1 with correlation coefficient of 0.99. The within-day and day-to-day precisions (CV) of this method were 4.5% and 7.0%, respectively, with recoveries of 95-102% (10-1000 ng.ml-1). There was no interference with nifedipine, amiodarone, propranol, and verapamil. A pharmacokinetic study on m-nifedipine was carried out in 8 rabbits. A better computer fitted to a two-compartment model was observed using 3P87 program. The parameters obtained were as follow: Vc 6.3 L.kg-1, Cl 0.021 L.kg-1.min-1, T1/2 alpha 30 min, T1/2 beta 230 min, AUC 102 micrograms.min.ml-1.

Stable expression of functional human cytomegalovirus immediate-early proteins IE1 and IE2 in HeLa cells

The major immediate-early (IE) genes 1 and 2 of human cytomegalovirus (HCMV) encode proteins that regulate the expression of HCMV genes as well as some other viral and cellular genes. In order to study the expression and function of these IE gene products, we established several HeLa cell lines that stably expressed the 68-kD IE1 protein, the 82-kD IE2 protein, or both proteins. The IE proteins expressed in these cell lines were biologically active, as shown by transient chloramphenicol acetyltransferase assays. Transcription from the major IE promoter was augmented in the IE1-expressing cells, while transcription from the HCMV early gene UL84 promoter was activated in the IE2-expressing cells. In addition, we found that the IE2-expressing cells established colonies in soft agarose more efficiently than the parental HeLa and the IE1-expressing cells. Furthermore, expression of both the IE1 and IE2 proteins was increased by treatment of these cell lines with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate. Thus, our cell lines provide a useful system to study the regulation of IE gene expression in human cells as well as to study transaction by HCMV IE proteins on various viral and cellular genes.

Hyperamylasemia following cardiopulmonary bypass

In order to study the occurrence of postbypass hyperamylasemia, 75 patients undergoing cardiopulmonary bypass (CPB) were studied from March 1989 to January 1990. There were 49 males and 26 females. Among them, 27 had congenital heart disease, 30 had valvular disease, and 18 had coronary artery disease. There were 27 patients with at least one elevated serum amylase sample after operation. Thus, the overall incidence of hyperamylasemia was 36%. As compared with the preoperative data (1.3%), there was a statistically significant difference in the occurrence of hyperamylasemia (p less than 0.05). Three patients had overt clinical pancreatitis postoperatively. There was no positive correlation between the serum amylase level and the occurrence of pancreatitis (p greater than 0.05). Forty-two cases had a significant elevation of the amylase creatinine clearance ratio (ACCR) after CPB. However, there was no significant difference between the groups with pulsatile and nonpulsatile CPB (p greater than 0.05). Three patients (4%) died in our series. The causes of death were heart failure in two and fulminant pancreatitis associated with low cardiac output in one. Although our experience in dealing with pancreatitis improved survival, mortality was still high (33.3%) in our series. Nevertheless, there was no apparent correlation between mortality and postbypass hyperamylasemia (p greater than 0.05). Logistic regression analysis was used to analyze the risk factors of the occurrence of hyperamylasemia, and the analysis revealed that patients with coronary artery disease were susceptible to postbypass hyperamylasemia. Our studies indicate that the use of total serum amylase or ACCR to monitor for the occurrence of pancreatitis in postbypass patients is inadequate.(ABSTRACT TRUNCATED AT 250 WORDS)

T lymphocyte changes in open heart surgery

To investigate the effect of open heart surgery on T lymphocytes and their subpopulations, 20 patients, who had undergone moderate- to high-dose fentanyl anesthesia and a cardiopulmonary bypass (CPB), were studied using flow cytometry techniques and monoclonal antibodies during and after surgery. The ages of these patients ranged from four to 61 years with eight being male and 12 being female. The disease entity consisted of four with coronary, six with congenital and 10 with valvular heart disease. No cyanotic patients were included in this study. Peripheral blood samples were collected before anesthesia, immediately before the surgical incision, on the first postoperative day (POD1) and on the second postoperative day (POD2), respectively. We found no significant changes in the percentage of total T cells (T3), or helper (T4) and suppressor (T8) T cells during anesthesia before the surgical incision. On POD1, all T lymphocyte subset percentages decreased significantly when compared to pre-operative values (total T cells: 58.4 +/- 12.6 vs 24.4 +/- 8.4, helper T cells: 33.3 +/- 10.1 vs 15.4 +/- 6.3, suppressor T cells: 23.0 +/- 6.4 vs 10.0 +/- 4, all p less than 0.001) but returned to preoperative levels on POD2. Throughout the study period, there were no significant changes in the T helper cell to T suppressor cell ratio. In spite of the transient decrease in T lymphocytes and their subpopulations, no clinical evidence of infection was noted in any patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Formation of large, sedimentable transcription complexes with VARNA genes and other related genes

We have used an Eppendorf centrifuge for isolation of transcription complexes assembled on VARNA genes and other related genes with NTP-depleted cell-free extracts. Similar to the 5 S rRNA gene, sedimentable, stable transcription preinitiation complexes could be assembled from two VARNA genes, two EB virus-specific EBER genes, four human tRNA genes, and one human Alu-family RNA gene, suggesting that the 5 S rRNA-specific transcription factor, TFIIIA, was not required for formation of these sedimentable, stable preinitiation complexes. Parameters affecting assembly of these complexes were sequences in circular DNA templates, sizes and sequences of linear DNA templates, temperature and incubation time. These complexes were stable at from 4 to 37 degrees C, and somewhat stable to salt wash. From results of effects of various mutations on assembly of these sedimentable complexes, we concluded that they were transcription machineries. Addition of the supernatant and partially purified factors to salt-washed complexes stimulated their transcription, we concluded that these sedimentable complexes were minimal transcription machineries containing suboptimal quantities of loosely bound transcription factors, TFIIIB, and RNA polymerase III. DNase 1 footprints of these sedimentable preinitiation complexes showed that two regions were protected, from +34 to +80 including the B block promoter element, and from +98 to +105. Similar DNase 1 footprints were also obtained from salt-washed complexes and stable preinitiation complexes isolated by molecular sieve column chromatography.

Organization of multiple regulatory elements in the control region of the adenovirus type 2-specific VARNA1 gene: fine mapping with linker-scanning mutants

The adenovirus type 2-specific virus-associated RNA 1 (VARNA1) gene is transcribed by eucaryotic RNA polymerase III. Previous studies using deletion mutants for transcription have shown that the VARNA1 gene has a large control region which is composed of several regulatory elements. Twenty-five exact linker-scanning mutations in the control region, from -33 to +77, of this gene were used for definition of the number and boundaries of these elements. The effects of these mutations on transcription and competition for transcription factors in human KB cell extracts revealed five positive regulatory elements. The essential element, which coincided with the B block, was absolutely required for both transcription and formation of stable complexes. A second element, which included the A block, was also required for both transcription and formation of stable complexes. Although this element is not as essential as the B-block element, together with the B-block element it may be necessary for formation of the most basal form of transcription machinery. Therefore, these two elements are the promoter elements in this gene. In addition, one possible element in the interblock region and two elements in the 5' flanking region were also required for efficient transcription, but they were moderately required for formation of stable complexes. Transcription of these mutants and the wild-type gene using an extract of 293 cells was stimulated at least threefold over that with the KB cell extract, as expected. Similar regulatory elements of this gene were revealed, however, when the 293 cell extract was used for transcription of these mutants, suggesting that the E1A-mediated specific transcription factors act on the transcription machinery in a sequence-nonspecific manner.

Oral administration of an attenuated strain of canine adenovirus (type 2) to raccoons, foxes, skunk, and mongoose

An attenuated strain of canine adenovirus type-2 (CAV-2) was administered orally to 2 foxes (Vulpes fulva), 6 raccoons (Procyon lotor), a skunk (Mephitis mephitis), and a mongoose (Herpestus auropunctatus). Blood was collected weekly from the animals to monitor CAV-2 virus-neutralizing antibody titers. All animals had increases in titers. Sera from 8 foxes, 30 mongooses, 52 raccoons, and 22 skunks trapped in the field had naturally occurring antibody to CAV-2.

Defining the functional domains in the control region of the adenovirus type 2 specific VARNA1 gene

The outer boundaries of the internal transcriptional control region in the VARNA1 gene have been located from positions +10 to +69. To further define the detailed organization of the functional domains in this region and the function(s) of the 5' flanking sequence, and to obtain a more detailed insight into other transcriptionally important sequences, we have constructed 77 mutants with deletion endpoints at almost every one to five base-pairs in the entire region from -30 to +160 for transcriptional studies. Using our highly active crude extract under our assay conditions, and quantitatively measuring the transcriptional efficiency and competing strength of each mutant, we have revealed new features of important transcriptional control sequences and defined the transcriptional functions of several functional domains in this gene. The essential domain is from +59/+63 to +66/+68, which corresponds to the B block sequence. This is smaller than that defined previously. The second most important domain is the region from +12/14 to +40, which includes the A block sequence that dictates the wild-type major start site and amplifies the events started by the B block region, mediated through factors and RNA polymerase III. Furthermore, the domain from -5 to +11 affects the use of certain start site(s). Moreover, the 5' flanking region from -30 to +1 contributes 80 to 90% of the overall transcriptional efficiency of the gene. Finally, our transcriptional studies of mutants deleted of the A block sequence and all of the upstream sequence indicated that an intimate interaction between the two blocks is essential for initiation of transcription. Furthermore, the B block sequence is more important than the A block sequence in the transcription reaction. The mechanism and control of transcriptional initiation in the VARNA1 gene is similar to that in some tRNA genes, but differs from that in others.

Termination sequences in the control region of the Ad2-specific VARNA2 gene

Both VARNA genes in the adenovirus genome are transcribed by host DNA-dependent RNA polymerase III. Nevertheless, late in infection the mass ratio of VARNA2 to VARNA1 in adenovirus-infected human KB or HeLa cells is about 1:40. This difference is most likely due to differences in promoter strength which may be attributed to sequence differences in the control regions of the two genes. To investigate this possibility, the two genes were cloned into separate plasmid molecules and their transcription efficiencies were compared in vitro. The VARNA2 gene was transcribed in vitro at least 50 times less efficiently than the VARNA1 gene. The competing strengths of the two genes were similar, which suggests that the B block sequence in the VARNA2 gene may be fully functional for sequestering factors. Therefore, the major difference must reside in the region upstream of the B block. By analyzing the hybrid RNAs transcribed from a hybrid gene and 27 fused genes in which only the control region of the VARNA1 gene was fused to various lengths of the 5'-flanking and the coding regions of the VARNA2 gene, one major and one minor termination site, which caused premature termination, were revealed downstream of the A block sequence and in the 5'-flanking region of the VARNA2 gene, respectively. The presence of termination sequences, a suboptimal interblock spacing, and an altered A block sequence in the control region may result in a weaker promoter in the VARNA2 gene.

Functions of and interactions between the A and B blocks in adenovirus type 2-specific VARNA1 gene

The internal transcriptional control region (ITCR) of VARNA1 gene consists of a 33-base-pair (bp) interblock sequence and two 12-bp sequence blocks that are highly conserved in most of the genes transcribed by RNA polymerase III. To define the functions of and study the interactions between the two blocks, we have constructed mutants with altered interblock sequence or spacing for transcription. The results of transcription efficiencies and competing strengths indicated that the interblock sequence was dispensable and the A and B blocks were essential for transcription control. One of the major functions of the interblock sequence was to maintain an optimal spacing for an intimate interaction between the two essential blocks. Shortening or elongating the interblock spacing in the mutants beyond this range drastically decreased the transcription efficiencies and competing strengths of these mutated genes. To further study how the interaction between the two blocks leads to initiation, the start sites and sizes of RNA products of the mutants were determined. When the interblock spacing was less than 105 bp, the wild-type start site was dictated by the A block after an interaction with the B block through proteins. However, when the interblock spacing was longer than 105 bp, several new start sites located closer to the B block were preferentially used. This suggests that new start sites may be dictated by the B block when its interaction with the A block is weakened by longer spacing. The mechanisms of interaction between the bipartite domain in this gene leading to initiation are different from those in tRNAs and Alu-family RNA genes.

Identification of lactate dehydrogenase-M polypeptide translated in vitro from human and mouse tumor cell poly(A)-containing messenger RNA

Rabbit anti-human lactate dehydrogenase-5(M4) antisera were raised which cross-reacted with mouse lactate dehydrogenase M polypeptide. The antisera were used for identification of human and mouse LDH-M polypeptides synthesized using an in vitro system directed by the mRNAs. The in vitro translation products directed by both mRNAs were similar in size and immunologically identical to the authentic LDH-M polypeptides. The sizes of the mRNAs encoding for both human and mouse LDH-M polypeptides were similar, about 15S (1445 nucleotides) and were shorter than the corresponding rat mRNA which is about 18S (1765 nucleotides).

Adenovirus DNA-directed transcription of 5.5S RNA in vitro

A cell-free system developed from human KB cells was used to transcribe 5.5S RNA from deproteinized adenovirus DNA in vitro. The cell-free RNA synthesis is dependent upon exogenous templates, ribonucleoside triphosphates, and cell-free postmitochondrial supernatant of human KB cells. The synthesis of 5.5S RNA is inhibited only by high levels of alpha-amanitin; therefore it is carried out by RNA polymerase III. The rate of synthesis was linear for at least 2 hr, indicating reinitiation. The 5.5S RNA synthesized in vitro is similar to the corresponding in vivo RNA in size, sequence, and coding region on adenovirus type 2 DNA. In this report is demonstrated in vitro synthesis of a facsimile of an in vivo transcript directed by deproteinized DNA in a mammalian cell-free postmitochondrial supernatant system.

Prolonged transcription in a cell-free system involving nuclei and cytoplasm

A cell-free system for nuclear-directed transcription has been developed that gives prolonged synthesis in the presence of cytoplasm. The nuclear and cytoplasmic components have been prepared from Krebs II ascites tumor cells for most experiments but further observations indicate that components prepared from other cell types may be used. After an initial 5- to 10-min period of relatively rapid RNA synthesis a linear rate ensues for 2-3 hr. In the absence of cytoplasm no net RNA synthesis occurs after the initial 10-min period. Experiments with alpha-amanitin suggest that about half of the cell-free synthesized RNA is made by RNA polymerase II, the enzyme believed to be responsible for messenger synthesis in vivo.The conditions used for RNA synthesis were derived from conditions found to be optimal for protein synthesis that proceeds linearly for 2-3 hr. It has not yet been possible to demonstrate the synthesis of protein from cell-free synthesized RNA in this system. A major problem here is that isolated nuclei, even when carefully washed, contain a great deal of translatable RNA.

Cell-free synthesis of rat growth hormone

Growth hormone has been synthesized in a cell-free system derived from Krebs II ascites cells, under the direction of RNA prepared from rat pituitary tumor (GC) cells. Growth hormone synthesized in the cell-free system was identified by precipitation with antiserum against growth hormone developed in baboon, followed by electrophoretic analysis of the dissolved precipitate on sodium dodecyl sulfate-polyacrylamide gels. RNA from both the membrane and the post-membrane fractions of the cytoplasm of GC cells stimulated protein synthesis in the cell-free system, but only RNA from the membrane fraction was found to direct the synthesis of growth hormone.