Prediction of the human pharmacokinetics of troglitazone, a new and extensively metabolized antidiabetic agent, after oral administration, with an animal scale-up approach

We have attempted to predict the human pharmacokinetics of troglitazone after oral administration based on animal data. Troglitazone is a new antidiabetic agent that exhibits a high-metabolic clearance and is metabolized mainly in the liver to sulfate and glucuronide conjugates. The prediction of the area under the plasma concentration-time curve (AUCp.o.) and bio-availability (F) in humans after oral administration was initially attempted by use of allometric equations involving the oral plasma clearance of total (CLp.o.) or unbound drug (CLp.o.,fu), or the hepatic intrinsic clearance of unbound drug (CLuint) and animal body weight. The exponents in the allometric equations between the clearances and body weights were 0.63 to 0.82 with high correlation coefficients (r > .98), and there was no marked difference in predictability by the three methods. Next, the prediction of the range of plasma profiles after oral administration to humans was attempted by the following series of steps: (1) calculation of the exponent and coefficients in the allometric relationships between body weight and parameters, such as total body plasma clearance (CLi.v.) and various distribution volumes (Vss, V beta and Vc) based on animal data; (2) estimation of the absorption rate constant (ka) from allometric relationship to body weight, and estimation of F value from the predicted AUCp.o. (3) description of the plasma concentration-time profiles after oral administration by an equation involving the allometric exponents and coefficients, ka, F and body weight. The observed and simulated plasma profiles were similar and the predicted AUCp.o. values were 60 to 120% of those observed. These methodologies will be useful for predicting the human pharmacokinetics after oral dosing from animal data.

Rapid rewarming causes an increase in the cerebral metabolic rate for oxygen that is temporarily unmatched by cerebral blood flow. A study during cardiopulmonary bypass in rabbits

BACKGROUND

Jugular venous hemoglobin desaturation during the rewarming phase of cardiopulmonary bypass is associated with adverse neuropsychologic outcome and may indicate a pathologic mismatch between cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2). In some studies, rapid rewarming from hypothermic cardiopulmonary bypass results in greater jugular venous hemoglobin desaturation. The authors wished to determine if rewarming rate influences the temperature dependence of CBF and CMRO2.

METHODS

Anesthetized New Zealand white rabbits, cooled to 25 degrees C on cardiopulmonary bypass, were randomized to one of two rewarming groups. In the fast group (n = 9), aortic blood temperature was made normothermic within 4 min. In the slow group (n = 9), aortic blood temperature was made normothermic over 25 min. Cerebral blood flow (microspheres) and CMRO2 (Fick) were determined at baseline (25 degrees C), and at brain temperatures of 28 degrees, 31 degrees, 34 degrees, and 37 degrees C during rewarming.

RESULTS

Systemic physiologic variables appeared similar between groups. At a brain temperature of 28 degrees C, CMRO2 was 47% greater in the fast rewarming group than in the slow group (2.2 +/- 0.5 vs. 1.5 +/- 0.2 ml O2.100 g-1. min-1, respectively; P = 0.01), whereas CBF did not differ (48 +/- 18 vs. 49 +/- 8 ml.100 g-1.min-1, respectively; P = 0.47). Throughout rewarming, CBF increased as a function of brain temperature but was indistinguishable between groups. Cerebral metabolic rate for oxygen differences between groups decreased as brain temperatures increased.

CONCLUSIONS

Cerebral venous hemoglobin desaturation with rapid rewarming is caused by an increase in CMRO2 that is temporarily greater than the increase in CBF. This mismatch may indicate a transient abnormality in flow-metabolism coupling, or the effect of temperature gradients on oxygen transfer from hemoglobin to brain.

Multitracer study on uptake and excretion of trace elements in rats

The multitracer technique was first applied to the investigation of the uptake and excretion behaviour of trace elements in rats. A multitracer solution, prepared by irradiation of a gold target with a 14N-beam from the RIKEN Ring Cyclotron, was orally administered to male Wistar rats. The uptake and excretion rates of 23 elements, Be, Mn, Co, Zn, As, Rb, Sr, Y, Zr, Ce, Pm, Eu, Gd, Tb, Er, Tm, Yb, Lu, Hf, W, Re, Ir and Pt, were simultaneously determined under strictly identical experimental conditions. For some of the elements, the results obtained were consistent with previous reports on uptake and excretion of the elements in animals. For the other elements, unique behaviour was revealed for the first time as described in the present work. These results show that the multitracer technique has excellent reliability and versatility for a comparative study of the uptake and excretion of many different elements in animals.

A new appliance for condylar positioning (clamp system)

A new appliance for condylar positioning during sagittal split ramus osteotomy (SSRO) of the mandible is presented. The application procedure and our method of condylar repositioning are described.

Dual brain stem projection from the cortical masticatory area in guinea-pig

The cortical masticatory area (CMA) in the guinea pig is subdivided into the anterior and posterior parts (A-CMA and P-CMA), based on the pattern of the CMA-induced rhythmical digastric EMG burst and the cytoarchitecture. The anterograde tracing of horseradish peroxidase from the A-CMA and P-CMA revealed, in addition to a common projection to the region around the trigeminal motor nucleus and the parvicellular reticular formation bilaterally, a massive projection to the ipsilateral superior colliculus (SC) from the A-CMA but not from the P-CMA. The results suggest a dual brain stem projection system from the CMA: the direct pyramidal route from the P-CMA and the SC-mediated indirect route from the A-CMA.

A class of single-stranded telomeric DNA-binding proteins required for Rap1p localization in yeast nuclei

We have identified a class of proteins that bind single-stranded telomeric DNA and are required for the nuclear organization of telomeres and/or telomere-associated proteins. Rlf6p was identified by its sequence similarity to Gbp1p, a single-stranded telomeric DNA-binding protein from Chlamydomonas reinhardtii. Rlf6p and Gbp1p bind yeast single-stranded G-strand telomeric DNA. Both proteins include at least two RNA recognition motifs, which are found in many proteins that interact with single-stranded nucleic acids. Disruption of RLF6 alters the distribution of repressor/activator protein 1 (Rap1p), a telomere-associated protein. In wild-type yeast cells, Rap1p localizes to a small number of perinuclear spots, while in rlf6 cells Rap1p appears diffuse and nuclear. Interestingly, telomere position effect and telomere length control, which require RAP1, are unaffected by rlf6 mutations, demonstrating that Rap1p localization can be uncoupled from other Rap1p-dependent telomere functions. In addition, expression of Chlamydomonas GBP1 restores perinuclear, punctate Rap1p localization in rlf6 mutant cells. The functional complementation of a fungal gene by an algal gene suggests that Rlf6p and Gbp1p are members of a conserved class of single-stranded telomeric DNA-binding proteins that influence nuclear organization. Furthermore, it demonstrates that, despite their unusual codon bias, C. reinhardtii genes can be efficiently translated in Saccharomyces cerevisiae cells.

In vivo biological behavior of a water-miscible fullerene: 14C labeling, absorption, distribution, excretion and acute toxicity

BACKGROUND

Water-soluble fullerenes have recently been shown to exhibit considerable in vitro biological activity including cytotoxicity, site-selective DNA cleavage and inhibition of HIV protease. To assess the potential of these compounds as drugs, studies on the in vivo behavior of fullerenes are needed. We therefore set out to synthesize a radiolabeled, water-soluble fullerene, in order to obtain data on the oral absorption, distribution and excretion of this class of compounds.

RESULTS

We synthesized a 14C-labeled water-soluble [60]fullerene using dipolar trimethylenemethane, which undergoes cycloaddition to [60]fullerene. When administered orally to rats, this compound was not efficiently absorbed and was excreted primarily in the feces. When injected intravenously, however, it was distributed rapidly to various tissues, and most of the material was retained in the body after one week. The compound was also able to penetrate the blood-brain barrier. Acute toxicity of the water-miscible fullerene was found to be quite low.

CONCLUSIONS

Although the water-soluble fullerenes (and possibly their simple metabolites) are not acutely toxic, they are retained in the body for long periods, raising concerns about chronic toxic effects. The fact that fullerenes distribute rapidly to many tissues suggests that they may eventually be useful to deliver highly polar drugs through membranes to a target tissue, however, and they may even have applications in the delivery of drugs to the brain. Recent advances in fullerene synthetic chemistry may also make it possible to control fullerene absorption/excretion profiles in the future.

Production of functional human bone morphogenetic protein-2 using a baculovirus/Sf-9 insect cell system

A clone of a human Bone Morphogenetic Protein-2 (hBMP-2) cDNA was obtained from a cDNA library established from human dental pulp cells. After subcloning hBMP-2 cDNA into Autographa californica nuclear polyhedrosis virus, the recombinant baculovirus was transfected to Sf-9 cells. Immuno-reactive recombinant hBMP-2 (rhBMP-2) was detected by a polyclonal antibody against Xenopus BMP-2 in the transfected insect cells but not in the culture media. Three days after treatment with the lysate of the transfected Sf-9 cells, increase in alkaline phosphatase activity of a murine stromal cell line, ST2, was detected. Subcutaneous implantation of rhBMP-2 produced in the insect cells induced formation of cartilage, bone and bone marrow in the rats. The present data indicated that the rhBMP-2 preparation produced in the insect Sf-9 cells had a comparable activity to that produced in mammalian cells.

[Cell cycle arrest induced by epidermal growth factor on human squamous cell carcinoma cell lines]

Although human squamous cell carcinoma (SCC) cell lines frequently contain an elevated number of epidermal growth factor (EGF) receptor accompanied with amplification of EGF receptor/c-erbB gene, it is well known that EGF inhibits the growth of these cells in culture at doses that stimulate the growth of epidermal keratinocytes and dermal fibroblasts. To study this growth inhibitory effect of EGF on the SCC cell lines, 3H-thymidine incorporation into DNA and cell cycle distribution were analyzed. In HSC-1 and NA cells, which contain the highest number of EGF receptor among these SCC cell lines, the inhibition of 3H-thymidine incorporation was apparent 2 to 4 hours after treatment with 100 ng/ml of EGF and reached more than 95% inhibition after 24 hours. Two-color cell cycle analysis using fluorescein isothiocyanate (FITC)-conjugated anti-Bromodeoxyuridine (BrdU) antibody and propidium iodide revealed that this inhibitory effect was due to cell cycle arrest not only in G1 but also in G2 phase. This effect was well correlated to the sensitivity to the growth inhibitory effect of EGF among the 4 SCC cell lines. These observations suggest that the SCC cells contain altered machineries which regulate the normal cell growth in both G1 and G2 phases, and the EGF affects these machineries via overexpressed its receptor.

TEL+CEN antagonism on plasmids involves telomere repeat sequences tracts and gene products that interact with chromosomal telomeres

In Saccharomyces cerevisiae, circular plasmids that include either a centromere (CEN-plasmids) or a telomere sequence (TEL-plasmids) segregate more efficiently than circular ARS-plasmids. In contrast, circular plasmids that include both telomere and centromere sequences were unstable, a property we term TEL+CEN antagonism. TEL+CEN antagonism required a telomere repeat tract longer than 49 bp although the distance and relative orientation of the centromere and telomere sequences was not critical. TEL+CEN antagonism was alleviated in strains carrying different rap1 alleles including rap1ts, rap1s, and rap1t alleles. Mutations SIR2, SIR3, SIR4, NAT1 and ARD1, genes that influence transcriptional silencing at telomeres and at the silent mating type loci, abolished TEL+CEN antagonism Mutation of SIR1 also partially alleviated TEL-CEN antagonism. In some sir mutant strains short yeast artificial chromosomes (YACs), which are normally unstable, became more stable, suggesting that the same mechanism that caused TEL+CEN antagonism on circular plasmids may contribute to the instability of short linear plasmids.

Expression on outer membranes of mannose residues, which are involved in osteoclast formation via cellular fusion events

Osteoclast, the bone-resorbing cell, is formed from hematopoietic precursors via cell-cell fusion. To evaluate the possibility that under certain specific conditions mannose residues may be expressed on the mammalian cell surface, we examined the action of pradimicin derivatives, which bind specific sugars such as the mannose residue, on the formation of osteoclast induced in the coculture of mouse spleen cells with mouse stromal cells, a process in which cell-cell fusion is involved. Osteoclast formation was inhibited by treatment of this coculture system with pradimicin at the later stage (day 4-7), and this inhibition was specifically abrogated by mannose-rich yeast mannan. During the 8-day cocultivation, osteoclast formation was blocked by the pradimicin on days 6 and 7, when mononuclear preosteoclasts fused into multinucleated osteoclasts. With an interactive laser cytometer ACAS570, fluorescein isothiocyanate-labeled pradimicin was observed to bind osteoclast progenitors at the fusion stage and to have no binding affinity for osteoclast progenitors at the early stage (day 0-3) or for osteoclasts, which were formed after performing fusion between mononuclear preosteoclasts. These results suggest that mannose residues were expressed on outer membranes of monocytes under pathophysiological conditions and that they were involved in the osteoclast formation via cellular membrane fusion events.

A new repositioning system for the proximal segment in sagittal split ramus osteotomy of the mandible

A new repositioning system for the proximal segment in sagittal split ramus osteotomy (SSRO) of the mandible was developed. Preparation and application of the system are described.

Effect of freeze-dried poly-L-lactic acid discs mixed with bone morphogenetic protein on the healing of rat skull defects

Porous poly-L-lactic-acid discs were prepared by a freeze-drying method (FDPLLA). During preparation of the discs, semipurified bone morphogenetic protein (BMP) was mixed with the poly-L-lactic acid (500 micrograms BMP per disc). The discs were implanted in the skull defects of rats and retrieved after 2 or 4 weeks. With the FDPLLA/BMP discs, new bone formation was observed at 2 weeks after implantation. On the other hand, plain FDPLLA discs failed to produce new bone formation even at 4 weeks after implantation. Calcium content of the retrieved FDPLLA/BMP discs was statistically higher than that of plain FDPLLA discs. These results suggest that FDPLLA may be an effective delivery system for BMP and that the FDPLLA/BMP disc may potentially have usefulness as a bone graft substitute.

Enhancement of telomere-plasmid segregation by the X-telomere associated sequence in Saccharomyces cerevisiae involves SIR2, SIR3, SIR4 and ABF1

We have previously shown that circular replicating plasmids that carry yeast telomere repeat sequence (TG1-3) tracts segregate efficiently relative to analogous plasmids lacking the TG1-3 tract and this efficient segregation is dependent upon RAP1. While a long TG1-3 tract is sufficient to improve plasmid segregation, the segregation efficiency of telomere plasmids (TEL-plasmids) is enhanced when the X-Telomere Associated Sequence (X-TAS) is also included on the plasmids. We now demonstrate that the enhancement of TEL-plasmid segregation by the X-TAS depends on SIR2, SIR3, SIR4 and ABF1 in trans and requires the Abf1p-binding site within the X-TAS. Mutation of the Abf1p-binding site within the X-TAS results in TEL-plasmids that are no longer affected by mutations in SIR2, SIR3 or SIR4, despite the fact that other Abf1p-binding sites are present on the plasmid. Mutation of the ARS consensus sequence within the X-TAS converts the X-TAS from an enhancer element to a negative element that interferes with TEL-plasmid segregation in a SIR-dependent manner. Thus, telomere associated sequences interact with TG1-3 tracts on the plasmid, suggesting that the TASs have an active role in modulating telomere function.

[Transcranial Doppler monitor in the case of selective cerebral perfusion]

Six patients underwent ascending aorta and aortic arch replacement for aneurysmal disease between 1991.12-1992.2 using the cardiopulmonary bypass technique with selective cerebral perfusion from right axillary artery. For four patients, intraoperative transcranial Doppler monitorings of left MCA flow velocity were done. We added left carotid artery perfusion for 5 patients because of old age; 1, intraoperative finding of anisocoria; 1 and low left MCA flow velocity on the TCD monitor; 3. After the addition of left side perfusion, the left MCA flow velocity on the TCD monitor recovered to normal level in the 3 patients. TCD reflected the cerebral perfusion state every minutes and seemed to be very useful monitor in selective cerebral perfusion. It also suggested that unilateral cerebral perfusion does not supply enough blood flow in contralateral side of brain in many cases. To another patient who also underwent aortic arch replacement, we examined preoperatively left MCA flow velocity on the TCD monitor under left carotid artery compression. This "carotid artery compression test" was thought to suggest the degree of right to left intracranial collateral blood flow via Willis's circle. TCD image, when the left carotid artery was clamped, was compared with the result of preoperative "carotid artery compression test". But we can't evaluate the results quantitatively now.

Plant regeneration from protoplasts of peppermint (Mentha piperita L.)

Enzymatically isolated leaf-derived protoplasts of peppermint (Mentha piperita L.) were cultured in modified B5 medium containing 1 mg/l NAA, 0.4 mg/l BA, 0.5% sucrose, 0.5 M mannitol and 0.1% Gelrite (first medium). After 30 d culture at 25°C in the dark, protoplasts formed colonies consisting of about 100 cells. Gelrite medium blocks were transferred into liquid medium to promote further growth. Colonies of 0.5 mm transferred to 0.2% Gelrite solidified medium (same components as first medium) formed green calli (1-2 mm) under incubation in the light. Green calli transferred to differentiation medium (B5, 0.1 mg/l NAA, 5 mg/l BA, 2% sucrose, 0.2 M mannitol, 0.2% Gelrite) developed shoot buds after 3-4 weeks. Whole plants were recovered following rooting of shoots in B5 medium without hormones.

[6 cases of CABG post coronary stent]

In recent years, percutaneous transluminal coronary angioplasty (PTCA) has been actively carried out as a therapeutic method of the ischemic cardiopathies, and Stent therapy has been clinically applied as settlement method of problematical points of the acute occlusion and dissection of the coronary artery by PTCA. We experienced 6 cases necessitated coronary artery bypass graft (CABG) after insertion of Palmaz-Schatz Stent until March 1992. The emergent bypass was carried out in 3 of 6 cases because thrombotic occlusion developed although Stent was inserted in thrombotic occlusion after PTCA, while 2 cases were not life-saved because of the cardiac function was worsened before operation. Other 3 cases were life-saved by expectant treatment even though stenosis developed again after Stent therapy. Stent therapy is a useful method, while severity in cases using CABG and operative complexity are expected by development of new problematical point in the future.

Monitoring bovine embryo viability with early pregnancy factor

The viability of the bovine embryo was monitored by measuring the early pregnancy factor (EPF). The EPF activity was measured by the rosette inhibition test before and after artificial insemination (AI) at natural estrus (n = 14), and after superovulatory treatment followed by embryo removal on day 7 after AI (n = 5). In the cows inseminated artificially at natural estrus, there were significant differences (p < 0.01) in the rosette inhibition titer (RIT) between pregnant and non-pregnant cows on day 13-16 and day 20-25 after AI. In the 8 pregnant cows, the RIT remained more than 5 from day 6-9 after AI. In the 6 non-pregnant cows, two patterns were observed. In one pattern, RIT rose transiently to more than 5 and decreased to less than 4 thereafter. In the other pattern, RIT remained less than 4 throughout the experimental period. The former pattern suggested early embryonic death, while the latter suggested that fertilization had not taken place or that early embryonic death had occurred before the first blood collection on day 6-9 after AI. In the cows superovulated followed by embryo removal on day 7 after AI, the RIT values were all less than 4 on the day of AI (day 0), rose to more than 5 on day 3 and thereafter then until the day of embryo removal on day 7. In 4 cows, the RIT decreased to less than 4 by 3 days after embryo removal, and in the remaining one cow, the RIT decreased to less than 4 by 7 days after embryo removal. These findings suggest that the measurement of EPF activity is useful for monitoring the viability of bovine embryos.

Telomere-mediated plasmid segregation in Saccharomyces cerevisiae involves gene products required for transcriptional repression at silencers and telomeres

Plasmids that contain Saccharomyces cerevisiae TG1-3 telomere repeat sequences (TRS plasmids) segregate efficiently during mitosis. Mutations in histone H4 reduce the efficiency of TRS-mediated plasmid segregation, suggesting that chromatin structure is involved in this process. Sir2, Sir3 and Sir4 are required for the transcriptional repression of genes located at the silent mating type loci (HML and HMR) and at telomeres (telomere position effect) and are also involved in the segregation of TRS plasmids, indicating that TRS-mediated plasmid segregation involves factors that act at chromosomal telomeres. TRS plasmid segregation differes from the segregation of plasmids carrying the HMR E silencing region: HMR E plasmid segregation function is completely dependent upon Sir2, Sir3 and Sir4, involves Sir1 and is not influenced by mutations in RAP 1 that eliminate TRS plasmid segregation. Mutations in SIR1, SIN1, TOP1, TEL1 and TEL2 do not influence TRS plasmid segregation. Unlike transcriptional repression at telomeres, TRS plasmids retain partial segregation function in sir2, sir3, sir4, nat1 and ard1 mutant strains. Thus it is likely that TRS plasmid segregation involves additional factors that are not involved in telomere position effect.