Synthesis and electronic properties of ferrocene-filled double-walled carbon nanotubes

Double-walled carbon nanotubes (DWNTs) are filled with ferrocene molecules by a vapour diffusion method for the first time. The as-synthesized ferrocene-filled DWNTs are characterized by transmission electron microscopy (TEM), energy-dispersive x-ray spectrometry (EDX) and Raman spectroscopy. Electronic properties of double-walled carbon nanotubes (DWNTs) filled with ferrocene molecules are studied by fabricating them as the channels of field-effect transistor (FET) devices. Our results reveal that electronic properties of ferrocene-filled DWNTs are greatly modified due to the charge transfer between ferrocene molecules and DWNTs. In addition, after ferrocene molecules are decomposed inside DWNTs, electronic properties of DWNTs exhibit a further change due to Fe encapsulation, and unipolar n-type semiconducting DWNTs are consequently obtained.

Development of a simple method to evaluate medical staff radiation dose and its application to a software system supporting PET facility operation

In recent years, positron-emitting labelled radiopharmaceuticals have come to be used in conjunction with positron emission tomography (PET) in various clinical diagnoses. Radiation exposure of the medical staff is a key issue in the design of PET facilities intended to handle large numbers of persons for PET diagnosis. As a first step, the radiation dose to individuals who received radiopharmaceuticals was calculated using a mathematical phantom model and the EGS4 electromagnetic cascade Monte Carlo code and MCNP Monte Carlo code. Dose rate behind a lead shield was also calculated for various lead thicknesses. The radiation dose distribution around a syringe containing a positron emitter was calculated. The calculated dose distributions were fitted to polynomial equations. These calculations were evaluated against measurements. The second step was to evaluate medical staff dose at a specified time by superimposing dose distribution from each person who received radioisotopes taking into account radioactive decay. In this way, we developed software to support PET facility operation, namely, planning, prediction, control of medical staff dose and facility operation. This system was also designed to schedule daily radiopharmaceuticals production and to manage radioactive wastes by taking decay time into account.

Hypotension and resistance to lipopolysaccharide-induced shock in transgenic mice overexpressing adrenomedullin in their vasculature

BACKGROUND

Adrenomedullin (AM) is a vasodilating peptide involved in the regulation of circulatory homeostasis and in the pathophysiology of certain cardiovascular diseases. To determine the extent to which chronic AM overproduction affects circulatory physiology under normal and pathological conditions, we used a preproendothelin-1 promoter to establish transgenic mouse lines overexpressing AM in their vasculature.

METHODS AND RESULTS

Transgenic mice overexpressing AM mainly in vascular endothelial and smooth muscle cells exhibited significantly lower blood pressure (BP) and higher plasma cGMP levels than their wild-type littermates. Blockade of NO synthase with N(G)-monomethyl-L-arginine elevated BP to a greater degree in AM transgenic mice, offsetting the BP difference between the 2 groups. Despite their lower basal BP, administration of bacterial lipopolysaccharide elicited smaller declines in BP and less severe organ damage in AM transgenic mice than in wild-type mice. Furthermore, the 24-hour survival rate after induction of lipopolysaccharide shock was significantly higher in the transgenic mice.

CONCLUSIONS

A chronic increase in vascular AM production reduces BP at least in part via an NO-dependent pathway. In addition, smaller responses to LPS in transgenic mice suggest that AM is protective against the circulatory collapse, organ damage, and mortality characteristic of endotoxic shock.

Synergistic effect of combining theophylline and drugs that potentially elevate serum creatine kinase

An increase in the serum creatine kinase (CK) level is one of the side effects of theophylline; on rare occasions, the increase may be followed by rhabdomyolysis. Theophylline is often administered with drugs that potentially elevate the serum CK level (CK-elevating drugs) such as beta-agonists and steroids. However, the effects of the combined treatment of theophylline and CK-elevating drugs have not been reported. We, therefore, retrospectively investigated the effects of combined treatment on the serum CK level, in 391 asthmatic outpatients. In this study, the number and type of the CK-elevating drugs administered, and the serum levels of CK and theophylline, were investigated. The patients were divided into four groups: the theophylline-treated and CK-elevating drug-treated group, the theophylline-treated and non-CK-elevating drug-treated group, the non-theophylline-treated and CK-elevating drug-treated group, and the non-theophylline-treated and non-CK-elevating drug-treated group. The theophylline-treated and CK-elevating drug-treated group showed about 100% higher serum CK levels (225 IU/L) than any other group (102-124 IU/L), and no increase in the serum theophylline level. This result indicates that there is a synergistic effect of theophylline and CK-elevating drugs on the serum CK level. The combined treatment of theophylline and CK-elevating drugs induces a synergistic increase in the serum CK level, indicating not pharmacokinetic but pharmacodynamic interactions with these drugs.

A comparison of the hypotensive and hypoglycaemic actions of an angiotensin converting enzyme inhibitor, an AT1a antagonist and troglitazone

OBJECTIVE

To define the relationship between changes in insulin sensitivity and attenuation of hypertension.

METHODS

We investigated whether troglitazone (CS-045, an insulin sensitizer) has an antihypertensive effect in fructose (FRU)-fed Wistar rats with insulin resistance and simultaneously compared its hypotensive efficacy with those of alacepril (ALA, an angiotensin converting enzyme inhibitor) and TCV-116 (an AT1a receptor antagonist). Male rats aged 8 weeks were divided into five groups: controls fed normal chow, a FRU group fed FRU-rich (55%) chow, a FRU plus ALA group fed 30 mg/kg ALA per day, a FRU plus TCV-116 group fed 1 mg/kg TCV-116 per day and a FRU plus CS-045 group fed 70 mg/kg CS-045 per day). After 8 weeks, the body weight and systolic blood pressure were recorded and glucose tolerance was determined by glucose loading (2 g/kg, intraperitoneally) and a steady-state plasma glucose (SSPG) method. The plasma membrane glucose transporter 4 content in gastrocneumius muscle was determined by Western blot analysis.

RESULTS

FRU increased blood pressure from 125 mmHg in controls to 141 mmHg (P < 0.01). ALA and TCV-116 administration decreased blood pressure to 111 and 107 mmHg, respectively (P < 0.01). CS-045 administration lowered blood pressure significantly to 121 mmHg. Area under the curve levels for plasma insulin during glucose loading increased from 1.7 in controls to 3.6 ng/ml x h in FRU-fed rats, but were lowered by the three drugs. SSPG levels increased from 12.5 in controls to 18.3 mmol/l in FRU-fed rats (P < 0.01), but were decreased by ALA and TCV-116 administration (P < 0.01). CS-045 administration also lowered SSPG levels to 15.3 mmol/l (P < 0.05). FRU-feeding induced a 1.24-fold increase in plasma membrane glucose transporter 4, which was not affected by ALA and TCV-116 administration, but was augmented 1.82-fold by CS-045 administration. Furthermore, the increased triglyceride level after FRU was diminished both by ALA and by CS-045 administration.

CONCLUSION

These results suggest that, in the insulin-resistant state, troglitazone, an angiotensin converting enzyme inhibitor and an AT1a receptor antagonist show comparable hypotensive and hypoglycaemic effects.