A new class of diacidic nonpeptide angiotensin II receptor antagonists: candesartan cilexetil

Blockade of the action of angiotensin ii (AII) has long been a target for development of novel antihypertensive agents. We recently discovered a novel class of potent non-peptide AII receptor antagonists, benzimidazole-7-carboxylic acids including candesartan. Candesartan is a highly potent and insurmountable antagonist selective in the angiotensin II type-I receptor (AT1). Structure-activity relationship (SAR) studies revealed that the adjacent arrangement of a lipophilic substituent, a tetrazolylbiphenylmethyl moiety and a carboxyl group was the important structural requirement for potent AII antagonistic activity. Especially, the presence of a carboxyl group at the 7-position was found to be essential for insurmountable antagonism. To improve bioavailability of candesartan, chemical modification was examined to yield candesartan cilexetil, a prodrug of candesartan. Candesartan cilexetil is a potent and long-acting blocker that, when given once-daily to patients, provides effective 24 hr blood pressure control.

[Pharmacological profiles of candesartan cilexetil (TCV-116)]

Candesartan cilexetil has shown potent and long-lasting antihypertensive effects in clinical trials and in several hypertensive animal models. In rabbit aortic preparation, candesartan, active form of candesartan cilexetil, decreased the maximal contractile response of angiotensin II (insurmountable inhibition). This inhibitory mode was different from that of other angiotensin II receptor blockers, and showed a shift to the right in the angiotensin II-induced contraction curve. In kinetic studies using bovine adrenal cortical membrane and tritiated candesartan, both receptor association and dissociation were found to be slow. The insurmountable inhibition of candesartan in vascular contraction is the result of its tight binding and slow dissociation from AT1 receptors. These characteristics are related to the potency and long duration of action in candesartan cilexetil.

Transfer of a pedicled venous flap containing perivenous areolar tissue and nerve: an experimental study

In this paper, we evaluated experimentally the feasibility of transferring a pedicled venous flap with perivenous areolar tissue into an ectopic site and investigated the role of each vein, the perivenous areolar tissue and nerve in the viability of pedicled venous flaps. Three groups of flaps were created using a rabbit-ear model: Group 1 (n = 11), containing perivenous areolar tissue and a draining vein; Group 2 (n = 10), perivenous areolar tissue, a draining vein and nerve; Group 3 (n = 10), only perivenous areolar tissue. Macroscopic, angiographic and histological assessments were performed 14 days after transfer. The total survival areas including superficial necrosis of Groups 1, 2 and 3 were 52.7%, 82.5% and 0%, respectively. There were significant differences in mean survival area and mean total survival area including superficial necrosis between Group 1 and Group 2 (P < 0.05). In contrast, all flaps in Group 3 became necrotic. These data suggest that a preserved vein is the necessary condition, and additional arterial flow through the preserved nerve and a small vascular network within the areolar tissue may play an important role in flap survival.

[Thoraco-abdominal impalement injury with diaphragmatic injury: a case report]

A 60-year-old man was admitted to our hospital because of impalement injury due to traffic accident. Chest X-ray on admission revealed normal lung field. CT scans of the chest and abdomen revealed slight pneumothorax and intra-abdominal organ protruding from abdominal cavity. An emergency operation was performed. Diaphragmatic injury was not detected during the abdominal procedure. On exploring the back wound, we found a laceration of 8 cm in diameter in the diaphragm and repaired it. Impalement injuries which have aspects of both blunt and penetrating trauma are uncommon. Accordingly, wound exploration and debridement of fistulous tract are necessary. In the case of thoraco-abdominal injuries by impalement, one should bear in mind the existence of diaphragmatic injury even with normal diaphragmatic shadow on chest X-ray.

Isolation of Biopterin-alpha-glucoside from Spirulina (Arthrospira) platensis and Its Physiologic Function

: A fluorescent substance was isolated from the cyanobacterium with a yield of 4.5 mg per 10 g of dried Spirulina (Arthrospira) platensis cells by gentle extraction and ethanol fractionation followed by column chromatography. The fluorescent substance, which has absorption maxima at 256 nm and 362 nm (pH 8.4), was identified as biopterin-alpha-glucoside by spectrophotometry and nuclear magnetic resonance spectroscopy. Biopterin-alpha-glucoside prevented decolorization of the photosynthetic pigments, chlorophyll a, phycocyanin, and carotenoids in photosynthetic vesicles of Spirulina platensis cells, by ultraviolet irradiation.

New hyperprolactinemia and anovulation model in common marmoset (Callithrix jacchus) and effect of cabergoline

We aimed to develop an anovulation model, using sulpiride-induced hyperprolactinemia in common marmosets. The serum prolactin level gradually increased during the twice-daily administration of sulpiride and reached a plateau after 4 days. Sulpiride produced as big a response at 10 mg kg(-1) as at 50 mg kg(-1). In this study, the length of the ovarian cycle was approximately 30 days in normal common marmosets. Serum progesterone and estradiol levels showed no consistent change during the first 2 months of treatment with sulpiride. When treatment with sulpiride had been continued for more than 2 months, serum progesterone and estradiol levels fell to within the range seen in the follicular phase of the normal cycle and absence of ovulation was recognized by laparoscopy. A single oral administration of cabergoline (at doses between 0.01 and 0.1 mg kg(-1)) dose dependently reduced the elevated serum prolactin level. Bromocriptine (at an oral dose of 10 mg kg(-1)) also reduced the serum prolactin level at 4 and 8 h after its administration. With bromocriptine, the prolactin level had recovered at 24 h, but with cabergoline at doses of 0.05 mg kg(-1) or more, it had still not recovered at 48 h. In anovulatory common marmosets, oral administration of cabergoline at a daily dose of 0.05 mg kg(-1) restored ovarian function and resulted in ovulation in 100% of the group (following a reduction in the serum prolactin level). Bromocriptine at a daily oral dose of 10 mg kg(-1) resulted in ovulation in 67% of the group, but this dose was about 200 times higher than the dose of cabergoline. We could produce an anovulatory model induced by sulpiride repeatedly administered over a long time period. It is suggested that, in this anovulatory model in common marmosets, cabergoline has a potent and long-lasting action as a dopamine D2 receptor agonist, and thus could be a useful drug for the treatment of galactorrhea and hyperprolactinemic amenorrhea and/or anovulation.

[Effective treatment of AFP-producing lung cancer with UFT]

The main form of chemotherapy for non small cell lung cancer is a multiple combination therapy centered on cisplatin (CDDP). We herein report a case in which a favorable course was obtained for a patient with extremely rare AFP-producing lung cancer by single oral administrations of UFT, following extirpation of brain metastasis. The patient was an 80-year-old male whose main complaints were headache and aphasia. Following close examination, a diagnosis was made of moderately differentiated adenocarcinoma with the primary lesion in S6 of the right lung. A metastatic lesion was found in the left occipital lobe. Blood AFP was an abnormally high 17,000 ng/ml. No tumorous lesions were found in the liver. The brain metastasis were extirpated to alleviate cranial nerve symptoms, and the tissue was found to be the same as that of the primary lesion. AFP staining of the tumor tissue revealed positive cells. Because there was proliferation in the primary tumor following surgery, administration of UFT (300 mg/day Tegafur) was begun. Four weeks later the tumor had begun to shrink, and at 15 weeks was judged to be a partial response. A reduction in AFP was also seen. The patient showed absolutely no side effects from UFT, thus enabling outpatient treatment. Good results were obtained both in reducing the tumor and in maintaining the patient's quality of life.

Inhibition of the angiotensin II Type 1 receptor by TCV-116: quantitation by in vitro autoradiography

Inhibition of angiotensin (Ang) II type 1 (AT1) receptors in various target tissues of adult Sprague-Dawley rats was studied after single oral administration of TCV-116. The effects of TCV-116 on Ang II-receptor binding were assessed by quantitative in vitro autoradiography using 125I-[Sar1,Ile8]Ang II as a ligand. Four hours after the administration of TCV-116 (1 mg/kg), Ang II-receptor binding was markedly inhibited in the kidney (20% of control), adrenal cortex (27%), thoracic aorta (57%), heart (55%) and testis (76%) where AT1 receptors predominate. In the brain, orally administered TCV-116 produced a significant inhibition of binding both to the circumventricular organs (38%), which are devoid of the blood-brain barrier (BBB), and to the discrete regions within the BBB such as the paraventricular hypothalamic nucleus (48%), nucleus of the solitary tract (60%). Twenty-four hours after the administration, Ang II-receptor binding had partly recovered to approximately 50-85% of control levels. In contrast, throughout the experimental period, Ang II-receptor binding was little affected in sites where Ang II type 2 (AT2) receptors predominate such as the adrenal medulla and the nucleus of the inferior olive. These data indicate that orally administered TCV-116 specifically binds to AT1 receptors both in peripheral tissues and the central nervous system.

Pharmacologic properties of candesartan cilexetil--possible mechanisms of long-acting antihypertensive action

Candesartan cilexetil has shown potent and long-lasting antihypertensive effects in clinical trials and in several animal models of hypertension. In spontaneously hypertensive rats, the duration of the antihypertensive effect of candesartan cilexetil was compared to those of losartan, valsartan, eprosartan, and irbesartan at the same degree of maximal blood pressure reduction. A single oral dose of candesartan cilexetil at 0.3 mg/kg reduced maximal blood pressure by about 25 mm Hg, and the antihypertensive effect of candesartan cilexetil lasted the longest, continuing for more than 1 week, without an effect on circadian rhythm. In a rabbit aortic preparation, candesartan, active form of candesartan cilexetil, decreased the maximal contractile response of angiotensin II. This inhibitory mode was different from that of other angiotensin II-receptor antagonists, and showed a shift to the right in the angiotensin II-induced contraction curve and/or a small depression of the maximal response. In kinetic studies using bovine adrenal cortical membrane and tritiated candesartan, both receptor association and dissociation were found to be slow. The dissociation rate of tritiated candesartan binding (t1/2 = 66 min) was five times slower than that of radiolabelled angiotensin II binding (t1/2 = 12 min). The insurmountable inhibition of candesartan in vascular contraction is the result of its tight binding and slow dissociation from angiotensin II AT1 receptors. These characteristics are related to the potency and long duration of action in candesartan cilexetil.

Effects of the new angiotensin II type 1 receptor antagonist KRH-594 on several types of experimental hypertension

The antihypertensive effect of dipotassium (Z)-2-[[5-ethyl-3-[2'-(1H- tetrazol-5-yl)biphenyl-4-yl]methyl-1,3,4-thiadiazoline-2- ylidene]aminocarbonyl]-1-cyclopentenecarboxylate (CAS 169328-25-0, KRH-594), a new angiotensin II type 1 (AT1) receptor antagonist, was studied in several experimental hypertensive models. The effects of KRH-594 on the circulating reninangiotensin system and on renal function were also investigated. Oral administration of KRH-594 (0.3 or 1 mg/kg) dose-dependently inhibited the angiotensin II-induced pressor response in common marmosets. KRH-594 (1, 3, or 10 mg/kg p.o.) dose-dependently exerted a long-lasting antihypertensive effect in spontaneously hypertensive rats (SHRs) and in 2-kidney 1-clip renal hypertensive rats (RHRs). Furthermore, repeated oral administration of KRH-594 (3 or 10 mg/kg/d) reduced blood pressure dose-dependently in SHRs, RHRs, and renal hypertensive dogs without tachycardia and with no evidence of a rebound phenomenon following drug withdrawal. On the other hand, in deoxycorticosterone acetate salt rats and normotensive rats, KRH-594 (10 or 30 mg/kg p.o.) did not have significant effects on systolic blood pressure. In SHRs, KRH-594 (3 or 10 mg/kg/d p.o. for 2 weeks) dose-dependently increased both plasma renin activity and the plasma angiotensin I concentration, but had no effect on the urinary excretion of sodium, potassium, and chloride or on creatinine clearance. These results suggest that KRH-594 should be effective in patients with essential or renal hypertension.

Haemodynamic and catecholamine responses to calcitonin gene-related peptide during volatile anaesthesia

PURPOSE

Calcitonin gene-related peptide (CGRP) produces vasodilatation, hypotension, and tachycardia. Tachycardia induced by CGRP may be due to sympathetic activation. Volatile anaesthetics attenuate activation of arterial baroreflexes. We examined the haemodynamic and endocrine effects of CGRP infusion (4 micrograms.kg-1) during anaesthesia with either enflurane or isoflurane in dogs.

METHODS

Measurements of haemodynamic variables and hormone assays for plasma catecholamines were made before, during, and after CGRP infusion. Anaesthesia consisted of induction with 25 mg.kg-1 pentobarbital, followed by either enflurane (n = 7) or isoflurane (n = 7) to achieve a 1.0 end-tidal minimum alveolar concentration in oxygen 100%.

RESULTS

Mean arterial pressure and systemic vascular resistance decreased (P < 0.01) and the reductions in both variables were similar during CGRP infusion in both groups. Cardiac index (CI) was increased (P < 0.01) in the enflurane group throughout the study while CI increased (P < 0.01) only during infusion in the isoflurane group. Heart rate (HR) remained unchanged (from 135 +/- 6 bpm to 134 +/- 7 bpm) in the enflurane group but tended to increase (from 162 +/- 9 bpm to 171 +/- 9 bpm) in the isoflurane group during infusion. Intergroup differences in HR were found (P < 0.05). Plasma epinephrine concentrations increased (from 42.4 +/- 12.7 pg.ml-1 to 115.3 +/- 41.8 pg.ml-1, P < 0.01) during infusion in the isoflurane group. However, these increases were suppressed (from 46.6 +/- 23.2 pg.ml-1 to 64.7 +/- 32.4 pg.ml-1) to a greater extent in the enflurane group.

CONCLUSION

The haemodynamic responses, except for HR, of CGRP infusion are similar during enflurane and isoflurane anaesthesia. Suppression of tachycardia induced by CGRP is greater with enflurane than with isoflurane. The differences in HR may be due to the roles of catecholamine responses resulting from the anaesthetic-induced sympathetic suppression.

[Deep-seated fungal infection in surgery]

In surgery, deep-seated fungal infection is not rare. In our institute, fungal infection was analyzed during postoperative periods. As pathogen, fungus was the second frequent pathogen after the operations for esophageal cancer and gastric cancer, and the third pathogen after hepatobiliopancreatic cancer and colon cancer. Furthermore, fungus was found more frequently pathogen from distant infection than that from local foci. Especially in CV catheter sepsis, fungus was main pathogen (60 %). In order to inhibit CV catheter sepsis, nutrition support team (NST) has been induced in our institute for prevention of external pathway of fungus. After NST, the frequency of CV catheter sepsis decreased from 12 % to 3.6 %, and the isolated frequency of fungus in catheter sepsis patients also decreased from 84 % to 16 %, respectively. It demonstrates that the activity of NST successfully prevents the external pathway of fungus in CV catheter indwelling patients. However, internal pathway (fungal translocation) still remains, and that issue has to be overcome. Molecular biological technique was applied for diagnosis of fungemia. PCR-RFLPs was performed by using specific primer of 18s rRNA in V4 region. Clinical samples were applied for PCR-RFLPs, and antifungal therapy was performed according as the results of PCR-RFLPs. It indicated that molecular biological technique was useful for diagnosis of fungemia.

Histologic findings in polyacrylamide-coated polytetrafluoroethylene (PTFE) arterial grafts in the rat abdominal aorta

To improve cell attachment without inducing thrombogenesis, the authors coated the inner surface of polytetrafluoroethylene (PTFE) prostheses (I.D.: 1 mm; length: 10 mm; wall thickness: 0.5 mm; fibril length: 30 microm) with polyacrylamide (PAA), known to have a strong antithrombotic effect (PAA-PTFE). They implanted the prostheses into the abdominal aorta of rats, and retrieved them at intervals of up to 9 months. Graft healing was observed under light and scanning electron microscopy. All the inner surfaces of the grafts examined were barely covered with fibrin or platelets. The PAA-coated fibers had many projections, in contrast to the original PTFE prostheses. Neo-endothelium was observed to be directly attached to these structural fibers of the PAA-PTFE grafts. Restoration of the neointima was also observed in these vascular prostheses.

Production of ethyl (R)-2-hydroxy-4-phenylbutanoate via reduction of ethyl 2-oxo-4-phenylbutanoate in an interface bioreactor

Ethyl (R)-2-hydroxy-4-phenylbutanoate [(R)-EHPB], a useful intermediate for the synthesis of various anti-hypertension drugs, was produced via microbial reduction of ethyl 2-oxo-4-phenylbutanoate [EOPB] in an interface bioreactor. Rhodotorula minuta IFO 0920 and Candida holmii KPY 12402 were selected as the best type culture and isolated yeasts, respectively. The highest enantiomeric excess of (R)-EHPB produced by R. minuta and C. holmii were 95 and 94%, respectively. C. holmii was used for the reduction of EOPB in a pad-packed interface bioreactor (inner volume, 3 liter). After incubation for 4 days, 4.4 g of (R)-EHPB was obtained via extraction with methanol followed by column chromatography. The overall yield, chemical purity, and enantiomeric excess of (R)-EHPB were 58%, 99.1%, and 90%, respectively.

Photostable chlorophyll a conjugated with poly(vinylpyrrolidone)-smectite catalyzes photoreduction and hydrogen gas evolution by visible light

Chlorophyll a was adsorbed to a synthetic smectite intercalated by poly(vinylpyrrolidone) (PVP) to form the chlorophyll-PVP-smectite conjugate (Chl-PVP-SME) having an absorption maximum at 677 nm. The conjugate was found to be stable toward light illumination in comparison with chlorophyll-smectite, chlorophyll-PVP, and free chlorophyll a. Chl-PVP-SME had a photoinduced activity for catalyzing the reduction of methyl viologen. Furthermore, the evolution of hydrogen gas was observed when an aqueous suspension containing Chl-PVP-SME, methyl viologen (an electron carrier), 2-mercaptoethanol (an electron donor), and hydrogenase was illuminated by visible light.

Effect of combination antiretroviral therapy upon rectal mucosal HIV RNA burden and mononuclear cell apoptosis

BACKGROUND

Pathogen-negative diarrhea is common in HIV infection and has been associated with clinical symptoms, histopathology, HIV expression, CD4+ lymphocyte depletion, cytokine mRNA expression, and apoptosis of lamina propria mononuclear cells.

OBJECTIVES AND METHODS

To examine the short-term (7-day) effects of treatment with combination antiretroviral therapies upon gastrointestinal symptoms and rectal mucosa in 15 HIV-infected subjects.

RESULTS

Treatment was associated with significant decreases in the perception of abdominal bloating and cramps. Similar declines in RNA burden and rises in CD4+ lymphocyte counts were found in blood and mucosa. Treatment was also associated with a fall in the number of lamina propria mononuclear cells undergoing apoptosis by in situ labeling, a change that correlated with the change in mucosal viral burden.

CONCLUSIONS

Peripheral blood and mucosal compartments are equally responsive to effective antiretroviral therapies. The detection of significant changes within 7 days of starting antiviral therapy implies that intestinal dysfunction may be a direct result of local HIV infection.

A method for prevention of arterialized venous flap necrosis

The authors used a delayed arteriovenous (A-V) shunt method to prevent congestion and necrosis of arterialized venous flaps. Two weeks before elevating the flap, an A-V shunt between the central artery and vein was created at the more proximal flap end. Twelve rabbits (24 flaps) were used for this experiment. Flaps were followed for 4 weeks. Twelve of 24 flaps survived completely; another 10 flaps showed partial necrosis; and two flaps became completely necrotic. These results demonstrated that this method is superior to a simple A-V shunt in preventing congestion and necrosis in the arterialized venous flap.

Cell cycle arrest and apoptosis of leukemia cells induced by L-asparaginase

Apoptotic cell death of murine leukemia cells induced by E. coli L-asparaginase was studied. Deprivation of L-asparagine from the culture of L5178Y cells by L-asparaginase caused the fragmentation of chromosomal DNA of the leukemia cells within 24 h. Prior to the degradation of DNA, cell cycles of L5178Y cells were found to be arrested in G1 phase, and evidence of the DNA strand breaks was initially observed in G1 phase cells as early as 8 h after the asparaginase treatment. Therefore, apoptosis of leukemia cells induced by L-asparaginase is an event that is associated with the cell cycle arrest in G1 phase.

Protective effects of candesartan cilexetil (TCV-116) against stroke, kidney dysfunction and cardiac hypertrophy in stroke-prone spontaneously hypertensive rats

The effects of chronic treatment with an angiotensin II receptor antagonist, candesartan cilexetil (TCV-116, 0.1, 1, 10 mg/kg), and an angiotensin converting enzyme inhibitor, enalapril maleate (enalapril, 10 mg/kg), on the development of end-organ damage were examined in stroke-prone spontaneously hypertensive rats (SHRSP). The control SHRSP developed severe hypertension with stroke signs and increased urinary protein excretion. TCV-116 (0.1 mg/kg) reduced the stroke incidence and urinary protein excretion without affecting the blood pressure. TCV-116 (1 and 10 mg/kg) and enalapril reduced blood pressure, the stroke incidence, the urinary indices and left ventricular weight. Circulating renin-angiotensin system (RAS) and renal renin mRNA expression were significantly accelerated or tended to be accelerated in the control SHRSP with end-organ damages. A low dose of TCV-116 tended to reduce the RAS indices in plasma by improving the damages, whereas a high dose (10 mg/kg) increased them by the reflexes with blocking RAS. The present results indicate that chronic All blockade reduces the increase in blood pressure, end-organ damages and RAS related to the damages in SHRSP.

Effects of the new angiotensin receptor antagonist dipotassium (Z)-2-[[5-ethyl-3-[2'-(1H-tetrazol-5-yl)biphenyl-4-yl] methyl-1,3,4-thiadiazoline-2-ylidene]aminocarbonyl]-1-cy clopentencarbox ylate on experimental cardiac hypertrophy and acute left ventricular failure

The cardiovascular effects of dipotassium (Z)-2-[[5-ethyl-3-[2'-(1H-tetrazol-5-yl)biphenyl-4-yl] methyl-1,3,4-thiadiazoline-2-ylidene]aminocarbonyl]-1-cyc lopentencarboxylate CAS 169328-25-0, KRH-594), a new angiotensin II type 1 (AT1) receptor antagonist, on pressure-overload cardiac hypertrophy in rats and on acute left ventricular failure in dogs were investigated. In rats with a 2-week abdominal aorta constriction, left ventricular weight (LVW) and systolic blood pressure (SBP) were significantly greater than in sham-operated rats. Oral administration of KRH-594 (10 or 30 mg/kg/day for 2 weeks) reduced the increases in both LVW and SBP. Another AT1 receptor antagonist, candesartan cilexetil (1 or 3 mg/kg/day for 2 weeks), also prevented this type of cardiac hypertrophy. In anesthetized dogs with a 60-min coronary ligation, left ventricular end-diastolic pressure (LVEDP) and total peripheral resistance (TPR) were raised, whereas the maximum first derivative of left ventricular pressure and cardiac output were both decreased. Intravenous administration of KRH-594 (3 mg/kg) significantly attenuated the increases in both LVEDP and TPR after coronary ligation. These results suggest that KRH-594, by reducing the cardiac afterload, may ameliorate pressure-overload cardiac hypertrophy in rats and produce an improvement in the hemodynamic status of dogs with acute left ventricular failure.