Physical and functional interaction of Runt-related protein 1 with hypoxia-inducible factor-1alpha.

Angiogenesis and hematopoiesis are closely linked and interactive with each other, but few studies were given to identify possible links between angiogenesis-promoting proteins and hematopoiesis-related transcription factors. Here we investigated the potential relationship of oxygen-sensitive alpha-subunit of angiogenesis-related hypoxia-inducible factor-1alpha (HIF-1alpha) with Runt-related protein 1 (Runx1, also known as acute myeloid leukemia-1, AML-1), an important hematopoietic transcription factor. The results demonstrated that Runx1 and HIF-1alpha proteins directly interacted with each other to a degree, in which Runt homology domain of Runx1 was mainly involved. Leukemia-related abnormal Runx1 fusion protein AML1-ETO, which fuses the N-terminal 177 amino acid residues of the Runx1 protein in frame to ETO (eight-twenty-one) protein, also interacted with HIF-1alpha protein with greater ability than Runx1 itself. More intriguingly, Runx1 overexpression inhibited DNA-binding and transcriptional activity of HIF-1 protein with reduced expression of HIF-1-targeted genes such as vascular endothelial growth factor, while silence of Runx1 expression by specific small interfering RNA significantly increased transcriptional activity of HIF-1 protein, suggesting that Runx1 inhibited transcription-dependent function of HIF-1. Vice versa, HIF-1alpha increased DNA-binding ability and transcriptional activity of Runx1 protein. All these data would shed new insight to understanding Runx1 and HIF-1alpha-related hematopoietic cell differentiation and angiogenesis.

Magnetocardiography of animals in magnetically shielded environment with active compensation.

A high-Tc 1st-order electronic superconducting quantum interference device (SQUID) gradiometer system is constructed to study the magnetocardiogram (MCG) of rabbits in a moderately magnetically shielded environment with active compensation. In the noisy hospital environment, the noise cannot be completely reduced with the 1st-order gradiometer, therefore, a reference SQUID with active compensation was used to further reduce the noise level leaking into the room. The MCG system was equipped with a x-y translation bed. We used a low-pass filter with the cut off frequency at 44 Hz, a high-pass filter with the cut off frequency at 0.1 Hz and the 60 Hz notch filter to reduce the power line interference. The noise level of the 1st order gradiometer MCG system in this moderately magnetically shielded room was about 1 pT/square root of Hz1/2 at 1 Hz. The MCG of a normal rabbits was measured with this system and a MCG contour map and a current density distribution was constructed.

High-Tc SQUID magnetocardiography imaging system.

We set up a high-Tc SQUID system for magnetocardiography (MCG) in a moderately magnetically shielded room. The electronically balanced gradiometer consists of superconducting quantum interference device (SQUID) magnetometer. One reference SQUID was mounted above the sensing SQUID while the sensing SQUID is seated at the bottom of the cryostat. The baseline of the gradiometer is varied from 5 cm to 7 cm. The output of the MCG signal was filtered with the band pass filter (0.5 - 40 Hz) and the power-line filter. The MCG system was used to detect the magnetic signal of the human heart. Equivalent current sources were used to study the inverse problem.

[Research on factors affecting neonatal tetanus and its prevention through immunization].

Neonatal Tetanus (NT) has been set by WHO as one of the most important diseases to be under control. Its incidence rate at some counties and cities in Southern Fujian province exceeded set out levels. Both retrospective and cohort studies were carried. It was found that in rural areas only 8.66% (319/3,683) pregnant women gave births at hospital and 94.85% (129/136) NT cases were delivered by untrained midwives. When TAT was tested in mothers and newborns, only 23.81% and 20.65% of them reached protective level. This shows the main reasons for high NT incidence rate were due to poor medical treatment during delivery and low antibody level. Using tetanus toxin (TT) to fully immunize pregnant women, no side effects were observed and TAT antibody levels for mothers and newborns were increasing to reach 100% (99/99) and 93.94% (93/99) relatively. When immunizing women at child-bearing age with TT, 90.40% (113/125) of them still had TAT up to protective level in 3 years. A total number of 8,882 newborns whose mothers had been fully vaccinated with TT were investigated, no NT case occurred. Among 4,835 newborns whose mothers did not receive vaccination, some NT cases were identified. The incidence rate was as high as 5.28%. These results showed that the TT vaccination in women at child-bearing age should be considered as the major strategy for NT prevention.

The disposition and metabolism of [14C]piritrexim in dogs after intravenous and oral administration.

The disposition of [14C]piritrexim ([14C]PTX) in male dogs after iv and po doses of 1.8 mg/kg was examined. After either route of administration, greater than 90% of the dose was recovered in the exreta within 72 hr; approximately 20% was recovered in urine and 70% in feces. [14C]PTX was extensively metabolized by dogs; unchanged drug accounted for less than 15% of the dose in the excreta. The O-demethylated metabolites, 2'- and 5'-demethyl PTX, the glucuronide conjugate of 2'-demethyl PTX, and the sulfate conjugate of 5'-demethyl PTX were the major metabolites. Unchanged drug accounted for a large proportion of the drug-related radiocarbon in plasma. The average plasma half-life of PTX after iv administration was 2.6 +/- 0.3 hr, and the average total body clearance was 0.33 +/- 0.13 liter/hr/kg. After po administration, peak plasma concentrations of 0.9 +/- 0.3 micrograms/ml occurred about 1.1 hr after the dose; the absolute oral bioavailability of PTX was 0.63 +/- 0.14. Because the O-demethyl metabolites were active dihydrofolate reductase inhibitors, 2'- and 5'-demethyl PTX were synthesized, and the pharmacokinetics and bioavailability of these compounds in dogs after iv and po administration (5 mg/kg) were examined. The plasma concentration-time data for both compounds after iv doses were described by a two-compartment model, with t1/2 beta = 1.3 and 0.8 hr for the 2'- and 5'- demethyl compounds, respectively. Neither compound showed significant advantages over PTX in terms of pharmacokinetics or bioavailability.

Phase I trial of piritrexim capsules using prolonged, low-dose oral administration for the treatment of advanced malignancies.

A phase I trial of piritrexim was conducted by use of a prolonged, low-dose oral schedule. A number of different regimens were tested, including daily dosing for 21 days followed by 7 days of no drug therapy; continuous dosing; and daily dosing for 5 of 7 days for 3 consecutive weeks followed by a week of rest. Dose escalation was accomplished by increasing the dosing frequency from once a day to twice a day and then to three times a day and by increasing the number of days of administration. Fifty-one patients with advanced cancer were entered in the study. One hundred twenty-four (96%) of 129 courses were considered assessable. Myelosuppression proved to be the dose-limiting toxic effect. Other toxic effects included stomatitis, nausea and vomiting, anorexia, diarrhea, skin rash, fatigue, and elevation of liver transaminase levels. Antitumor activity was observed in patients with melanoma and bladder cancer, and disease stabilization occurred in those with sarcoma and pheochromocytoma. The recommended dosing schedule for phase II clinical trials is 25 mg three times a day for 5 days for 3 consecutive weeks followed by 1 week of no drug therapy.

A phase I clinical and pharmacological study of weekly intravenous infusions of piritrexim (BW301U).

Thirty-eight patients with advanced resistant cancers were enrolled on this study of piritrexim (PTX; BW 301U) administered intravenously weekly for 4 weeks. Of 50 courses of treatment begun, 39 evaluable 4-week courses of the drug were completed by this group of patients. Dosages ranged from 44 to 530 mg/m2/week. One patient at each dosage level received an initial weekly dose of PTX in oral form accompanied by pharmacokinetic blood sampling after the oral dose and also after a subsequent intravenous dose. Toxicities included mild nausea and vomiting, and moderate to severe peripheral vein phlebitis. Anemia and thrombocytopenia were the dominant hematological toxicities. One patient with pulmonary metastases from malignant fibrous histiocytoma experienced a 12-week partial response to PTX treatment at a dosage of 400 mg/m2/week. Pharmacokinetic analysis of plasma for PTX concentrations was accomplished utilizing a competitive protein binding assay. The estimated total body clearance ranged from 136 to 173 ml/min/1.73 m2. Mean terminal half-life after intravenous administration was 5.61 +/- 2.38 h (S.D.), and after oral administration was 5.72 +/- 2.04 h. Mean systemic bioavailability after oral administration was 75 +/- 56%.

Pharmacokinetics of acrivastine after oral and colonic administration.

Six healthy male volunteers participated in this randomized, crossover open-label pharmacokinetic study consisting of two dosing segments separated by a washout period of at least 5 days. During each dosing segment, each volunteer received 12 mg of acrivastine, an investigational histamine H1-receptor antagonist, in a syrup form either orally or by colonic administration in random order. After oral and colonic administration, respectively, the following mean +/- SD pharmacokinetic parameters were obtained: Cmax 179 +/- 11 and 13.8 +/- 5.2 ng/ml; tmax, 0.85 +/- 0.13 and 3.60 +/- 0.56 hr; AUC0-12 hr, 576 +/- 57 and 104 +/- 46 hr.ng/ml. Differences between the oral and colonic administration for all three parameters were statistically significant (P less than 0.001). The mean +/- SD relative bioavailability of acrivastine from colonic compared to oral dosing was 0.18 +/- 0.09. It may be concluded, therefore, that appreciable absorption of acrivastine from the colon does not take place. These results suggest that comparison of pharmacokinetic profiles of some drugs after oral and colonic administration may be a useful technique for predicting bioavailability from a sustained release oral formulation.

Pharmacokinetics and bioavailability of zidovudine in humans.

The basic pharmacokinetic and bioavailability information on zidovudine was obtained during the initial phase I study. Following intravenous doses of 1.0 mg/kg every eight hours to 7.5 mg/kg every four hours, zidovudine plasma levels decay in a biexponential manner, indicating two-compartment pharmacokinetics. The mean half-life was 1.1 hours over this dose range and the total body clearance was approximately 1,900 ml/minute/70 kg, up to doses of 5 mg/kg. At 7.5 mg/kg, total body clearance decreased by 35 percent. The 5'-O-glucuronide was identified as a major metabolite of zidovudine in plasma and urine. This inactive metabolite is rapidly formed and cleared from plasma, with a half-life of one hour. No other metabolites have been found in humans. Renal clearance of zidovudine was estimated at 350 ml/minute/70 kg. Zidovudine penetrated the blood brain barrier as indicated by a cerebrospinal fluid:plasma ratio averaging 0.5, determined two to four hours after dosing. Following oral administration of zidovudine at doses from 2.0 mg/kg every eight hours to 10 mg/kg every four hours, peak plasma levels increased proportionately with dose; the average bioavailability was 65 percent. Since 90 percent of the drug was recovered in the urine as zidovudine or the 5'-O-glucuronide, the incomplete bioavailability is assumed to be the result of first-pass metabolism rather than incomplete absorption. Pharmacokinetic questions related to optimal use of the drug are currently being addressed.

Pharmacodynamic and pharmacokinetics of BW 825C: a new antihistamine.

The new H1-receptor antagonist BW 825C and triprolidine (2.5 and 5 mg) were administered to 12 healthy male volunteers in a double blind placebo controlled, balanced, crossover design. Histamine antagonism was measured by assessment of flare and weal areas after intradermal injection of histamine. The 2 compounds were approximately equipotent in blocking the flare and weal response to intradermal histamine and had a similar duration of action. Triprolidine impaired performance of vigilance and reaction time (p less than 0.05) compared with placebo while BW 825C did not. Drowsiness measured using visual analogue scales followed both triprolidine treatments, but not BW 825C. BW 825C had a plasma half-life (t1/2) of 1.7 +/- 0.2 h and triprolidine of 4.6 +/- 4.3 h. The peak plasma level of BW 825C was approximately 6 times that of triprolidine. It was concluded that BW 825C might be a clinically active H1-antagonist with reduced sedative side-effects.

Bioavailability of pseudoephedrine and triprolidine from combination and single-ingredient products.

The bioavailability of pseudoephedrine and triprolidine from combination and single-ingredient products was evaluated in a randomized, four-way crossover study. Healthy men volunteers received single doses of a tablet containing triprolidine hydrochloride and pseudoephedrine hydrochloride, a syrup containing the same two drugs, and single-ingredient tablets of each drug. Blood samples were collected before each dose and at 13 sampling times over 24 hours for determination of drug concentrations by radioimmunoassay. Observed peak concentration (Cmax), corresponding observed peak time (tmax), area under the plasma drug concentration-time curve from dosing to time infinity (AUC), and the ratio between plasma clearance and extent of bioavailability (CL/F) were determined. Nonlinear regression analysis was used to obtain estimates of lag time for absorption, first-order rate constant for absorption, first-order rate constant for elimination, and ratio between volume of distribution and extent of bioavailability. Data were analyzed for 19 of 20 men entering the study; data were complete for 16 of these. Pseudoephedrine concentrations were significantly different for the combination tablet and the syrup at four sampling times; no significant differences were found between pseudoephedrine concentrations for the combination tablet and single-ingredient tablet. Cmax, tmax, AUC, and CL/F for pseudoephedrine were not significantly different for the three formulations. Triprolidine concentrations at 8 hours were significantly higher for the combination tablet than for the single-ingredient tablet, and tmax for triprolidine was significantly higher for the combination tablet than for the syrup. For both pseudoephedrine and triprolidine, the combination tablet was bioequivalent to the syrup and to the single-drug tablets.

Pharmacokinetic quantitation of naltrexone controlled release from a copolymer delivery system.

Naltrexone release rates from a controlled release delivery system have been quantitated over a time period greater than one month in the monkey. The method requires calibration of the pharmacokinetic parameters of each monkey utilizing an intravenous bolus dose and assay of unchanged naltrexone levels in plasma as a function of time after dosing. Also required are periodic plasma levels of unchanged naltrexone obtained subsequent to administration of the delivery system. Release rates are then calculated as well as the total amount released. Application of the methodology to a biodegradable copolymer naltrexone delivery system in three monkeys showed an initial release rate of 3-8% of the dose per day over the first 3-5 days followed by a slow, rather constant release rate of 1-3% per day from day 5 to the time of the last measurable plasma sample (36-43 days). Comparison of alternative calculation methods using both experimental and simulated plasma naltrexone data verified the accuracy of the release rate calculations. The sum of the calculated total amount of naltrexone released plus the assayed amount remaining in the delivery system after removal from the animal accounted for 91-94% of the administered dose in the two monkeys in which complete data were obtained.

Influence of hemodialysis on acyclovir pharmacokinetics in patients with chronic renal failure.

The pharmacokinetic disposition of acyclovir was studied in six patients with chronic renal failure (CRF) and anuria. At the end of a one-hour intravenous infusion (2.5 mg/kg), the mean peak acyclovir plasma level (+/- SD), determined by radioimmunoassay, was 37.5 +/- 24.2 microM (8.4 +/- 5.4 microgram/ml), twice the level found at this dose in patients with normal renal function (NRF). In the CRF volunteers, significant plasma levels (3.0 +/- 1.4 microM) persisted at 47 hours after drug administration (before hemodialysis) whereas in the NRF patients levels dropped to less than 1 microM by 11 hours. Hemodialysis was started 47 hours after infusion and was continued for six hours. The pre-dialysis plasma drug level was reduced by 61.5 percent at 0.25 to 1.5 hours after the end of dialysis. The mean plasma t 1/2 during dialysis of 5.4 hours, the extraction ratio of 0.44, and the dialysis clearance for plasma of 113 ml/min indicate that acyclovir is efficiently removed by hemodialysis. One-half the suggested intravenous dose for a particular indication can be given every 24 hours and a similar replacement dose should be given after each dialysis.

Overview of acyclovir pharmacokinetic disposition in adults and children.

The metabolic disposition and pharmacokinetics of acyclovir have been studied as part of the clinical evaluation of the drug in humans. Data from 10 studies have been summarized and, when appropriate, pooled across studies for further analysis. The principal findings are as follows: Renal excretion is the major route of elimination of acyclovir and is dependent, in part, on active tubular secretion. Total body clearance (Cltot) and half-life are dependent on renal function as evaluated by estimated creatinine clearance (Clcr). Cltot is markedly reduced in the anuric patient. Plasma protein binding is low and drug interactions involving binding displacement are not anticipated. Acyclovir levels in cerebrospinal fluid are approximately 50 percent of corresponding plasma levels. Dose-independent pharmacokinetics is observed in the range of 0.5 to 15 mg/kg. Proportionality between dose and plasma levels is seen after single doses or at steady state after multiple dosing. Similar plasma levels are achieved in adults and pediatric patients (greater than 1 year) when equivalent doses are given based on body surface area. Intrasubject variability of acyclovir disposition is low. Much but not all intersubject variability in Cltot can be explained by differences in renal function. Dosage adjustment for various stages of renal impairment are proposed based on the observed relationship between Cltot and Clcr.

Pharmacokinetic quantitation of naltrexone release from several sustained-release delivery systems.

A method designed to quantitate in vivo naltrexone release rates from sustained-release systems has been applied to the evaluation of seven different naltrexone delivery systems in the monkey. The method consists of two phases: a single intravenous bolus dose quantitation of each monkey's pharmacokinetic parameters coupled with a delivery system study in which plasma naltrexone levels are measured throughout the time period of sustained-release. In vivo release rates and the total amount released are then calculated. It should be noted that these determinations require the analysis of unchanged naltrexone in plasma as the only experimental measurement. Data from injectable naltrexone pamoate microcapsule delivery systems indicate that 1) when these microcapsules are suspended in an aqueous vehicle, a significant part of the dose is released very rapidly, yielding release rate-time data that parallel a non-sustained-release control; 2) this rapid release for the aqueous vehicle is followed by a slow release phase lasting to about 24 days for the subcutaneous route and to about 45 days for the intramuscular route; and 3) when these microcapsules are suspended in an oily vehicle there is no initial rapid release, substantial release rates are obtained for at least 60 days, and an average of 89% of the dose is calculated to have been released. Data from implantable naltrexone delivery systems show that 1) the Alza system most closely approximates a zero-order release rate-time profile; 2) the Battelle system provides a rapid initial release followed by a slowly declining release rate; 3) the Dynatech system is characterized by a more rapid initial release rate of 3-8% of the dose per day over the first 3-5 days followed by a rather constant 1-3% per day to about day 36; and 4) essentially complete recovery of the dose was obtained for the Battelle and Dynatech systems.

Intracellular localization of growth hormones in plants.

Autoradiographic studies of Allium cernuum and Vicia faba root-tip cells treated with indoleacetic acidmethyl-C(14) or 2,4-dichlorophenoxyacetic acid-carboxyl-C(14) revealed nuclear and cytoplasmic labeling of the cells. The cytoplasmic labeling decreased with time after the removal of the labeled auxin, but nuclear and chromosomal labeling was retained for at least 120 hours.