Attenuation by ACE inhibitor drugs of alpha-adrenoceptor sensitivity in human vessels: possible differences related to drug lipophilicity

AIMS

We investigated the effect of angiotensin converting enzyme inhibitors (ACEIs) on postsynaptic adrenoceptor sensitivity and compared the effect of the lipophilic ACEI, quinapril, and that of hydrophilic agent, enalapril in human vessels.

METHODS

Alpha-adrenoceptor sensitivity was evaluated using the dorsal hand vein compliance technique. The dose-response curves of vasoconstriction to phenylephrine and prostaglandin F2alpha were obtained in healthy male volunteers.

RESULTS

The ACEIs shifted the dose-response curve of phenylephrine to the right and raised the median effective dose (ED50; 189.3 (57.6 ng min(-1)) of phenylephrine. Following quinapril administration, ED50 increased to 481.1 (101.8 ngmin(-1) compared with 266.8 (55.8 ngmin(-1) after enalapril (95% CI for differences; 31.1-397.5 ng min(-1)). Quinapril administration had no effect on the dose-response curve of PGF2alpha.

CONCLUSIONS

ACE inhibition attenuates alpha-adrenoceptor sensitivity in human vessels. The effect of quinapril, a lipophilic ACEI, was greater than that of enalapril, a hydrophilic ACEI. Lipophilic ACEIs may be more potent in vasodilating effect than hydrophilic ACEIs. Angiotensin II concentration in tissue rather than that in plasma may contribute to the alpha-adrenoceptor sensitivity of the vessels.

Characterization of functional domains of an embryonic stem cell coactivator UTF1 which are conserved and essential for potentiation of ATF-2 activity

We have recently cloned a cDNA encoding an embryonic stem cell transcriptional coactivator termed UTF1 from the mouse F9 teratocarcinoma cell line (Okuda, A., Fukushima, A., Nishimoto, M., Orimo, A., Yamagishi, T., Nabeshima, Y., Kuro-o, M., Nabeshima, Y., Boon, K., Keaveney, M., Stunnenberg, H.G., and Muramatsu, M. (1998) EMBO J. 17, 2019-2032). Here we have cloned a cDNA for human UTF1 and identified two highly conserved domains termed conserved domain (CD)1 and CD2. Human UTF1, like that of mouse, binds to ATF-2 and the mutagenesis analyses reveal that the leucine zipper motif within the CD2 of the UTF1 and metal binding motif of ATF-2 are involved in this interaction. The factor also binds to TATA-binding protein containing complex. By means of immunoprecipitation analysis, we mapped two domains which are independently able to bind to the complex. Importantly, both domains are located within the conserved domains (one in CD1 and the other in CD2). Furthermore, transient transfection analyses point out the importance of these domains for activating ATF-2. Thus, these results suggest that these two conserved domains identified here play important roles in activating specific transcription at least in part by supporting physical interaction between the upstream factor, ATF-2, and basal transcription machinery.

[Informed consent and surgical treatment in a 38-year-old female, Jehovah's witness with lung cancer]

A 38-year-old female was found to have abnormal lesion in the left lower lung by chest X-ray examination which was done for her periodical health examination in March, 1997. She was referred to our Institution for operation of the pulmonary lesion by her family physician. The pathology was reported to be adenocarcinoma by the preoperative bronchofiberscopy. As she was Jehovah's witness, she refused to receive either homologous or autologous blood transfusion on the ground of her faith. Prior to the operation, the consultation was held together with the patient, family and doctors in reference to the informed consent. In June, 1997, she had left lower lobectomy without blood transfusion. Postoperative course was uneventful. The problems of surgical treatment in Jehovah's witness rejected blood transfusion are discussed.

[Peripheral eosinophil counts relates the improvement of the skin lesions of atopic dermatitis patients more sensitive than serum eosinophil cationic protein levels]

We described the severity of skin lesions and detected peripheral eosinophil counts (Eos) and serum eosinophil cationic protein levels (s-ECP) in 81 patients with atopic dermatitis (male 33, female 48, age 20.7 +/- 8.8) at the first consultation. Eos were 583.3 +/- 560.2/mm3 and s-ECP were 18.0 +/- 21.7 micrograms/l (normal 6.88 +/- 3.46). After approximately 30 days treatment, the improvement of dermatitis were estimated and those lavatory findings were rechecked. Eos were 446.7 +/- 367.6/mm3 and s-ECP were 13.2 +/- 11.7 micrograms/l. At 5 percent level, positive correlations were observed between Eos and s-ECP (R = 0.75), Eos and the severity of dermatitis (R = 0.52) and s-ECP and the severity of dermatitis (R = 0.51) at the first consultation. We found a positive correlation between Eos and the improvement of dermatitis (R = 0.40) but no correlation between s-ECP and the improvement of dermatitis (R = 0.10). Eos related the improvement of the skin lesions of atopic dermatitis more sensitive than s-ECP.

UTF1, a novel transcriptional coactivator expressed in pluripotent embryonic stem cells and extra-embryonic cells

We have obtained a novel transcriptional cofactor, termed undifferentiated embryonic cell transcription factor 1 (UTF1), from F9 embryonic carcinoma (EC) cells. This protein is expressed in EC and embryonic stem cells, as well as in germ line tissues, but could not be detected in any of the other adult mouse tissues tested. Furthermore, when EC cells are induced to differentiate, UTF1 expression is rapidly extinguished. In normal mouse embryos, UTF1 mRNA is present in the inner cell mass, the primitive ectoderm and the extra-embryonic tissues. During the primitive streak stage, the induction of mesodermal cells is accompanied by the down-regulation of UTF1 in the primitive ectoderm. However, its expression is maintained for up to 13.5 days post-coitum in the extra-embryonic tissue. Functionally, UTF1 boosts the level of transcription of the adenovirus E2A promoter. However, unlike the pluripotent cell-specific E1A-like activity, which requires the E2F sites of the E2A promoter for increased transcriptional activation, UTF1-mediated activation is dependent on the upstream ATF site of this promoter. This result indicates that UTF1 is not a major component of the E1A-like activity present in pluripotent embryonic cells. Further analyses revealed that UTF1 interacts not only with the activation domain of ATF-2, but also with the TFIID complex in vivo. Thus, UTF1 displays many of the hallmark characteristics expected for a tissue-specific transcriptional coactivator that works in early embryogenesis.

Effects of astemizole on ventricular activation, effective refractory periods, RT intervals, and programmed stimulation-induced ventricular arrhythmias in dog hearts with myocardial infarction

To clarify the mechanisms of enhanced cardiotoxic effects of astemizole in ischemic hearts, we examined the effects of astemizole on ventricular activation, effective refractory periods (ERPs), RT intervals, and incidence of programmed electrical stimulation (PES)-induced ventricular arrhythmias in the dog heart after myocardial infarction. Myocardial infarction was produced by the two-stage ligation of left anterior descending coronary artery in dogs. At 7 days after ligation, bipolar electrodes were sutured on the ventricular surface of the infarcted and the normal zones for applying an electrical stimulation or recording the ventricular activation. Ventricular-activation delay was measured in a premature excitation, which was produced by a stimulation at a coupling interval between 300 and 140 ms on the ventricular surface of the normal zone. The ERP and the RT interval were determined during atrial pacing. The ventricular-activation delay increased after astemizole at doses of 0.3-3 mg/kg in the infarcted zone and at 3 mg/kg in the normal zone. Astemizole at doses of 0.3-3 mg/kg significantly prolonged the ERP to a greater extent in the infarcted zone than in the normal zone, and thus a dispersion of ERP between normal and infarcted zones increased. The RT interval in the normal zone significantly increased after astemizole to a greater extent at a long coupling interval. The RT interval in the infarcted zone also increased after astemizole at doses of 0.1-3 mg/kg to a greater extent than that in the normal zone. Astemizole at doses of 0.3-3 mg/kg increased the incidence of PES-induced ventricular arrhythmias. In conclusion, enhanced cardiotoxic effects of astemizole in ischemic hearts may be caused by increased activation delay in the ischemic regions and increased ERP dispersion in the ventricle.

Comparison of class II and class III activity of dl-sotalol in healthy volunteers

Racemic sotalol has demonstrated anti-arrhythmic properties which include Class II (beta blockade) and Class III (potassium channel blockade) activity. The Class II activity is demonstrated primarily in l-sotalol, and Class III activity is almost equipotent in each isomer. Class II and Class III activity of dl-sotalol was investigated following repeated oral administration (80 mg b.i.d.) for 7 days. Class II activity was evaluated according to the low frequency spectral power obtained by fast Fourier analysis of the R-R interval variation. Class III activity was evaluated according to the change in the QTc interval of the surface electrocardiogram. The low frequency spectral power decreased after administration of the first dose on day 1 and this trend continued throughout the duration of the study. The QTc interval did not change with dl-sotalol administration. These findings may suggest that Class II activity is more potent than Class III activity.

Effects of astemizole on ventricular activation delay and RT intervals in a canine myocardial infarction model

In order to clarify the arrhythmogenic effects of nonsedating antihistamines, we examined the effects of astemizole, a nonsedating antihistamine, on ventricular activation and RT intervals in a canine myocardial infarction model. Myocardial infarction was produced by two-stage ligation of the left anterior descending coronary artery in dogs. Seven days after ligation, bipolar electrodes were sutured on the ventricular surface of the infarcted and normal zones to apply an electrical stimulation or record the ventricular activation. An electrical stimulation with coupling intervals between 300 and 140 ms was applied on the ventricular surface of the normal zone during atrial pacing, and the ventricular activation delay was measured. The effect of astemizole on the RT interval was also determined during atrial pacing, sinus rhythm or after premature stimulation. The ventricular activation delay increased after astemizole at doses of 0.3 to 3 mg/kg in the infarcted and at 3 mg/kg in the normal zones, and the effect of astemizole was greater in the infarcted zone. Astemizole increased the RT interval in the normal zone to a greater extent at a long coupling interval. The increase in the RT interval was greater in the infarcted zone compared with that in the normal zone. In conclusion, astemizole increased the activation delay in the infarcted zone, probably through prolongation of the repolarization time, and its effect on the activation delay may be arrhythmogenic.

[A case of Jehovah's Witness underwent double valves replacement in reoperation]

The patient was a sixty five-year-old woman and Jehovah's Witness who refused either homologous or autologous blood transfusion on the ground of her faith. At the age of 47, she had closed commissurotomy for mitral valve stenosis. This time, because mitral valve restenosis and tricuspid valve regurgitation were found, double valve replacement, mitral and tricuspid, was performed on her, with an excellent result. It is expected that, in the near future, the indication for open heart surgery without blood transfusion will be increased by means of the following considerations as to blood loss preservation; 1. to shorten the time necessitating for an operation and reduce preoperative blood loss, 2. to improve cardio-pulmonary bypass system (Heparin coating etc), and 3. to augment the erythropoiesis (administration of EPO at the patient's own expense, etc.) and so on.

Enhanced effect of triazolam with diltiazem

AIMS

Triazolam, a triazolobenzodiazepine hypnotic agent, is metabolized by CYP3A4. Diltiazem is an inhibitor of this isozyme. The aim of this study was to determine if diltiazem affects plasma concentrations of triazolam in humans.

METHODS

We investigated the interaction between triazolam and diltiazem in a randomized, three-phase crossover study. Seven healthy male volunteers received orally either a single 0.25 mg dose of triazolam, a 0.25 mg dose of triazolam after a 3-day treatment of diltiazem (180 mg day-1), or a placebo. Plasma samples were collected to determine triazolam concentration over a 24 h period. The pharmacodynamic effects of triazolam were investigated using the peak saccadic velocity of eye movements (PSV), electroencephalogram (EEG), and visual analogue scale (VAS) through 8 h.

RESULTS

Diltiazem pretreatment significantly increased the area under the triazolam concentration-time curve (8.0 +/- 2.4 to 18.2 +/- 3.1 ng ml-1 h; P < 0.001; mean +/- s.d.). Peak triazolam concentration was increased (2.1 +/- 0.7 to 3.6 +/- 1.0 ng ml-1, P < 0.05) and the elimination half-life prolonged (4.1 +/- 2.1 to 7.6 +/- 1.9 h; P < 0.01). The PSV, EEG, and VAS of the triazolam plus diltiazem group revealed significant differences from the triazolam alone group or the control placebo group.

CONCLUSIONS

Diltiazem markedly affects the pharmacokinetics of triazolam and increases the intensity of its sedative effects. Inhibition of CYP3A isozyme by diltiazem may explain the observed pharmacokinetic interaction. Therefore, triazolam should be avoided when patients are using diltiazem.

Structural determination of stevastelins, novel depsipeptides from Penicillium sp

Structures of novel immunosuppressants, stevastelin A, B and B3(1) were determined by their spectroscopic and chemical studies. Three stevastelins were shown to be cyclic depsipeptides composed of a fatty acid and three amino acid moieties. The sequence of these moieties was determined to be as 3,5-dihydroxy-2,4-dimethylstearylvalylthreonyl (or O-sulfonylthreonyl in stevastelin A)-O-acetylserine. Cyclic structures were shown to be formed by ester linkages between the carboxylic group of the O-acetylserine moiety and the 5-hydroxy group of the fatty acid moiety in stevastelin A and B, and the 3-hydroxy group of the fatty acid moiety in stevastelin B3.

Comparative electrophysiological effects of the antidepressants fluvoxamine and amitriptyline in the canine heart after myocardial infarction

We studied the effects of fluvoxamine and amitriptyline on epicardial activation delay of premature excitations, the effective refractory period, and the incidence of ventricular arrhythmias by programmed electrical ventricular stimulation in the canine heart after myocardial infarction. Additionally, we investigated whether the inhibition of norepinephrine reuptake by amitriptyline contributes to epicardial activation delay or arrhythmias by combination with propranolol pretreatment. Amitriptyline, at a dose of 3 mg/kg, significantly prolonged epicardial activation delay of premature excitations in the infarcted zone in a frequency-dependent manner (n = 10). Amitriptyline also prolonged epicardial activation delay of premature excitations in the normal zone (n = 10). The effective refractory period in the infarcted zone was significantly prolonged by amitriptyline at a dose of 3 mg/kg (n = 8). Amitriptyline increased the incidence of ventricular arrhythmias induced by programmed electrical ventricular stimulation (n = 8). Propranolol did not affect the epicardial activation delay caused by amitriptyline or the incidence of ventricular arrhythmias induced by programmed electrical ventricular stimulation (n = 6). Fluvoxamine, on the other hand, had no significant effect on epicardial activation delay of premature excitations (n = 10) or the effective refractory period (n = 8) in both the infarcted and normal zones. Fluvoxamine did not increase the incidence of ventricular arrhythmias induced by programmed electrical ventricular stimulation (n = 8).

Demodex folliculitis on the trunk of a patient with mycosis fungoides

A 43-year-old man with tumour stage mycosis fungoides developed multiple follicular pustules on the trunk during total-skin electron beam therapy. A potassium hydroxide preparation of the contents of the pustules revealed the presence of Demodex mites. The patient was treated with 6% sulphur lotion with rapid improvement of the cutaneous lesions. We believe that this case represents a pustular folliculitis caused by Demodex mites. Immunosuppression associated with mycosis fungoides and its treatment may have resulted in the proliferation of this obligate parasite of the pilosebaceous follicle, and the development of the folliculitis.

Histological suture changes following retraction of the maxillary anterior bone segment after corticotomy

By cephalometric and dental cast analyses, the effects of corticotomy in combination with 45-50 days retraction of the maxillary anterior segment were evaluated in five female Japanese monkeys (Macaca fuscata). In addition, microscopic changes of the related sutures were examined. According to the analyses of the dental casts, the retraction of the maxillary anterior segment in the experimental group was increased when compared with that of the control group. There was no change in occlusal molar relationship. The cephalometric analysis revealed that the "Point A" and "Metal Implant" on the mid-sagittal site between the upper central incisors in the experimental group showed more pronounced retraction than that in two untreated control animals. These results were histologically evaluated by changes of the suture structure: irregularity of functional arrangement of component cells and fibers, an increase in number of cells, resorption and formation of bone, and an enlargement of the suture width. Resorption of tooth roots and alveolar bone, and irregularity of the periodontal ligament were observed. In general, these histological changes appeared more extensive in the control specimens compared with the experimental specimens. The osseous histological changes were mainly observed in the compact bone area, while in the spongy bone area of both control and experimental specimens only minimal changes occurred. These results demonstrated the efficacy of combining a corticotomy procedure with retraction of the maxillary anterior bone segment by an orthodontic force.

Heterogeneous chemotactic response of eosinophils from patients with atopic dermatitis to eosinophil chemotactic factors

The chemotactic response of eosinophils from 16 patients with atopic dermatitis (AD) to 5 eosinophil chemotactic factors (ECFs) were examined to clarify whether the response is associated with the clinical severity of AD. The factors included ECF-P15, -P16, -P17, -P18 and -P19 and were derived from a T cell line, STO-2. The patients were divided into 2 groups according to the percentage migration of eosinophils produced by the ECFs: a high-responding group (migration > 40%), and a low-responding group (migration < 30%). In a statistical analysis, eosinophils from patients with AD and atopic respiratory diseases (ARD) were found to be high-responding and those from patients with AD alone low-responding (p < 0.01). In a comparison of the chemotactic response of eosinophils from patients with AD alone at remission and at exacerbation, the percentage migrations in response to ECF-P15 and ECF-P16 at exacerbation were significantly higher than that at remission (p < 0.05). It is thus suggested that this type of heterogeneous response of eosinophils to STO-2-derived ECFs could provide a useful tool for evaluation of disease severity in patients with AD.