Peek-A-Boo Test: A Simple Test for Assessing the Effect of Anxiolytics on Fish Behavior

The potential of pharmaceuticals and personal care products to alter the behavior of aquatic organisms is a growing concern. To assess the actual effect of these substances on aquatic organisms, a simple but effective behavioral test is required. We devised a simple behavioral (Peek-A-Boo) test to assess the effect of anxiolytics on the behavior of a model fish (medaka, Oryzias latipes). In the Peek-A-Boo test, we investigated the response of medaka to an image of a predator fish (donko fish, Odontobutis obscura). The test revealed that the time taken for test medaka exposed to diazepam (0.8, 4, 20, or 100 µg/L) to approach the image was shorter by a factor of 0.22 to 0.65, and the time spent in the area close to the image was longer by a factor of 1.8 to 2.7 than in the solvent control group for all diazepam exposure groups (p < 0.05). Hence, we confirmed that the test could detect changes in medaka behavior caused by diazepam with high sensitivity. The Peek-A-Boo test we devised is a simple behavioral test with high sensitivity for fish behavioral alteration. Environ Toxicol Chem 2023;42:2358-2363. © 2023 SETAC.

Abstract P1-06-11: Microsatellite instability in triple negative breast cancers

Background:Microsatellite instability (MSI) is a phenotype resulting from defect in mismatch repair genes. The Food and Drug Administration approved anti-programmed death 1 (PD-1) immune checkpoint inhibitor for any solid tumor with MSI-high (MSI-H). Some tumors had good response to PD-1 blockade and it is a promising treatment for a part of refractory breast cancers. Our goal was to determine the frequency of MSI in triple negative breast cancer (TNBC), one of the most clinically aggressive subtypes.

Patients and Methods:This study included 228 patients with primary TNBC underwent resection without neoadjuvant chemotherapy between January 2004 and December 2014. Genomic DNA was extracted from formalin-fixed and paraffin-embedded tissue. Tumor and control DNA were amplified by polymerase chain reaction at the following 5 microsatellite markers: NR-21, BAT-26, BAT-25, NR-24, MONO-27. We classified the tumors as microsatellite stable(MSS), MSI-low or MSI-H.

Results: The mean age of patients was 59 years (range: 30-89) and all were women. T1 tumors were 57.9% and N0 were 67.5%. Meanwhile, the tumors with nuclear grade 3 were 66.2% and high Ki-67 (&gt; 30%) were 66.7%. Among the 228 tumors, 222 tumors (97.4%) revealed MSS, of which 6 (2.6%) revealed MSI and 2 (0.9%) were MSI-H. Among the MSI tumors, T and N factor were showed as follows: T1: 2 tumors, T2: 3 tumors, T3: 1 tumor, N0: 5 tumors and N1: 1 tumor. Of two MSI-H tumors, one showed T1N0 and another showed T2N0. The both of them showed nuclear grade 3, high Ki-67 (&gt; 30%) and had common following instable markers: NR-21, BAT-26 and BAT-25.

Conclusions: Our results demonstrated that the frequency of MSI-H was 0.9% (2/228). MSI might not be useful as a biomarker for immune check point inhibitors. MSI should be combined with another biomarker such as tumor mutational burden in TNBC.

Citation Format: Kurata K, Kubo M, Mori H, Kawaji H, Motoyama Y, Kuroki L, Yamada M, Kaneshiro K, Kai M, Nakamura M. Microsatellite instability in triple negative breast cancers [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-06-11.

Abstract P4-06-22: Transcription factor T-bet and PD-L1 expression in tumor microenvironment of triple-negative breast cancer

Background: Many analyzes regarding immunotherapies using checkpoint blockade has made it clear that tumor infiltrating lymphocytes (TILs) plays an important role in treating cancers with high levels of somatic mutations such as triple-negative breast cancer (TNBC). We reported the relationship between TILs and PD-L1 expression, and revealed that high-TILs/positive-PD-L1 expression population in TNBC was associated with better prognosis (Oncotarget 2017). However, its molecular mechanism is still unclear. Meanwhile, T-box transcription factor 21 (T-bet) which regulates effecter T-cells activation is derived by stimulation of T-cell receptor and IL-12. Activated T-cells work as antitumor lymphocytes by enhancing the production of cytokines such as INFγ. We focused on T-bet and examined the function of activated T-cells.

Patients and Methods: This study included 242 patients with primary TNBC who underwent resection without neoadjuvant chemotherapy at our three hospitals between January 2004 and December 2014. The immunohistochemistry scoring for CD8 and T-bet expression on TILs was defined as ≥30 per 0.00625mm2. PD-L1 positivity was defined as ≥1% of tumor cells staining positive for PD-L1.

Results: Of the 242 TNBC, CD8 on TILs was expressed as positive in 127 (52.5%) tumors, T-bet on TILs was expressed as positive in 67 (27.7%) tumors, and PD-L1 expression on tumor cells was expressed as positive in 99 (40.9%) tumors. T-bet expression was significantly correlated with CD8 expression (P&lt;0.0001) and PD-L1 expression (P=0.0004). There was no significant difference in recurrence free survival (RFS) and overall survival (OS) regardless of CD8 or PD-L1expression level. Meanwhile, the patients with T-bet-positive tumors had a longer OS, compared to those with T-bet-negative tumors (P = 0.13 in RFS and P = 0.047 in OS). The multivariate analysis revealed that T-bet expression on TILswas an independent and positive prognostic factor for OS(HR = 0.5, 95%CI 0.1-0.9, P = 0.035).

Conclusion: OS was significantly longer among patients with high T-bet expressing TNBC. These results may validate the significance of T-bet as a biomarker for various immunotherapies in TNBC.

Citation Format: Mori H, Kubo M, Kai M, Kurata K, Kawaji H, Kaneshiro K, Motoyama Y, Kuroki R, Yamada M, Nishimura R, Okido M, Oda Y, Nakamura M. Transcription factor T-bet and PD-L1 expression in tumor microenvironment of triple-negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-06-22.

[Surgical treatment for symptomatic arachnoid cysts]

During the period from 1983 to 1999, 12 patients with symptomatic arachnoid cyst were treated. The mean patient age was 20.6 years. The most common location was the middle fossa (10 cases). Initial CT scan revealed associated subdural hygroma in 7 patients and hydrocephalus in one. Clinical symptoms were related to increased intracranial pressure, cranio-megaly and seizure. One infant with a huge arachnoid cyst was treated, using a cystoperitoneal (CP) shunt. Four patients underwent membraectomy. Combination CP shunt and membraectomy was performed in 5 patients. The remaining 2 arachnoid cysts were complicated with subdural hygroma and, initially, they were observed conservatively, but hygroma gradually changed to hematoma. One was treated by irrigation and the other hematoma was spontaneously absorbed. Significant complications included extensive subdural effusion in one patient, contralateral chronic subdural hematoma in two, intracranial hypotension in two, and shunt dependency in one. There were no recurrences during the follow-up period (mean 3.6 years).

Migration of a lumboperitoneal shunt catheter into the spinal canal--case report

A 50-year-old female suffered upward migration of a lumboperitoneal (LP) shunt catheter into the spinal canal, manifesting as disturbance of short-term memory. Revision of the shunt confirmed that the tube had migrated into the spinal canal. The tube was pulled back into the peritoneal cavity and attached firmly to the fascia with a new anchoring device. LP shunts have the advantages of technical simplicity and extracranial procedure, but firm fixation is recommended since movements of the spine may cause proximal tube migration.

Direct clipping of a large basilar trunk aneurysm via the posterior petrosal (extended retrolabyrinthine presigmoid) approach--case report

A 53-year-old female presented with an unruptured, large basilar trunk aneurysm manifesting only as headache with no neurological deficits, including absence of cranial nerve dysfunction. Cerebral angiography disclosed a large aneurysm with a wide neck arising from the midbasilar artery. We treated the aneurysm surgically via the posterior petrosal approach. Five angled clips were applied sequentially to the aneurysm and the basilar artery was successfully reconstructed. Electrophysiological monitoring was continued during the operation and showed no changes. Following the operation, the patient suffered from transient right abducens nerve palsy, which persisted for 3 months. Postoperative angiography showed that the aneurysm was obliterated, and the patency of the basilar artery was preserved.

[A case of intravascular malignant lymphomatosis presenting as cerebral infarction]

A case of intravascular malignant lymphomatosis (IML) presenting as progressive cerebral infarction is reported. A 62-year-old previously healthy male developed progressive dementia. MRI of the brain at the nearest hospital revealed multiple infarcts with unknown etiology. His level of consciousness deteriorated rapidly, and then he was transferred to our hospital for further evaluation. High grade fever, raised serum C reactive protein (CRP), and raised lymphoma markers (serum LDH and soluble IL-2 receptor (sIL-2R)) were observed. Repeated brain MRI disclosed progression of multifocal cerebral infarctions. We considered IML most likely, and we performed muscle biopsy. However muscle biopsy didn't demonstrate any proliferation of neoplastic cells of lymphoid origin within small vessels. Thereafter IML was diagnosed by brain biopsy. The patient underwent chemotherapy, but died of pneumonia due to severe myelosuppression. IML is a rare disease but most commonly shows neurological symptomatology as its clinical manifestation. Dementia is the most common neurological symptom, and progressive multiple infarction is the most common of the MRI findings. Rapidly progressive dementia associated with multiple infarction, when elevated CRP, LDH and sIL-2R are observed in the laboratory data, is suggestive of IML.

[A case of psoriatic arthropathy complicated with spinal fracture and epidural hematoma]

A 78-year-old man with psoriatic arthropathy complicated with traumatic spinal fracture and epidural hematoma is reported. He had fallen down the stairs. On admission one hour after injury, he developed an incomplete C6 quadriparesis. CT revealed a C6-7 fracture and dislocation on sagittal reconstruction. MR imaging disclosed the compression of the spinal cord between the posterior margin of the vertebral body and an epidural hematoma. The patient had had the skin lesion, psoriasis vulgaris, for about 20 years and been previously treated for uveitis. Serological tests for rheumatoid factor and HLA B-27 were negative. Emergent laminectomy and evacuation of the epidural hematoma were carried out because of progressive neurological deterioration. Osteoporotic laminar bone and ossified yellow ligament were observed to have been fractured. Conservative therapy was selected for spinal instability. Although a respiratory complication occurred postoperatively, he was transferred to the rehabilitation facility in an improved neurological condition.

The spinal antinociceptive effect of FR140423 is mediated through kyotorphin receptors

We investigated the antinociceptive effect of a novel anti-inflammatory and analgesic drug, 3-(difluoromethyl)-1-(4-methoxyphenyl)-5-[4-(methylsulfinyl)phenyl]pyraz ole (FR140423), in the tail-pinch test in mice, and evaluated the mechanism of action of FR140423 using L-leucyl-L-arginine (Leu-Arg), a kyotorphin (endogenous Met-enkephalin releaser) receptor antagonist, L-NG-nitroarginine methylester (L-NAME), an inhibitor of nitric oxide (NO) synthase, and methylene blue (MB), an inhibitor of activation of guanylate cyclase. Oral administration of FR140423, at doses of 5-80 mg/kg, produced a dose-dependent antinociceptive effect with an ED50 value of 18 mg/kg. This antinociception was reversed by intrathecal (i.t.) (10 microg/mouse), but not by intracerebroventricular (i.c.v.) (100 microg/mouse), injection of Leu-Arg. Moreover, the antinociceptive effect of i.t. injection of FR140423 with an ED50 value of 3.7 microg/mouse was completely antagonized by co-administered Leu-Arg 10 microg/mouse. However, L-NAME (2000 mg/kg s.c.) and MB (200 mg/kg s.c.) did not antagonize the antinociception of FR140423. These findings suggest that FR140423 plays a role in nociceptive modulation in the spinal cord, being antinociceptive via the kyotorphin-Met-enkephalin pathway but not via the peripheral NO-cyclic GMP pathway.

[A case of high flow CCF with congestive hemorrhage]

The authors report a case of high flow CCF with intracerebral hemorrhage during treatment with endovascular coil embolization. A 52-year-old woman had been in good health until a sudden onset of orbital bruit and left orbital tinnitus occurred. Conjunctival chemosis and diplopia caused by left abducens palsy gradually progressed. Left internal carotid arteriography revealed a carotid-cavernous sinus fistula with direct high-flow shunt. The fistula drained into the superior orbital vein, inferior petrosal sinus, intercavernous sinus and sphenoparietal sinus with significant cortical reflux. The attempt at transarterial balloon occlusion failed. Then transvenous coil embolization was performed. During the course of endovascular treatment, follow up CT depicted intracerebral hemorrhage. Intracerebral hemorrhage was asymptomatic and thought to be caused by venous hypertension from cortical reflux. The patient underwent direct occlusion of the left sphenoparietal sinus for prevention of further hemorrhage via craniotomy. Lastly, the cavernous sinus was completely occluded by transvenous coil embolization. The signs and symptoms resolved 3 months after the procedures.

Comparative study of intraoperative mitomycin C and beta irradiation in pterygium surgery

AIMS

To compare the rate of recurrence and complication after surgery for primary pterygium performed by one surgeon using either intraoperative mitomycin C or beta irradiation.

METHODS

A retrospective study was performed of 164 eyes in 164 patients who had undergone primary pterygium surgery. After the pterygium was excised, the bare sclera was covered by sliding adjacent superior conjunctiva. 103 eyes received intraoperative mitomycin C (0.04%, 150 seconds) and 61 eyes beta irradiation (total dose 21.6 Gy). The mean follow up period was 20.2 (SD 17.9) months (range 1-66 months). Recurrence was defined as the postoperative regrowth of fibrovascular tissue crossing the corneoscleral limbus.

RESULTS

The recurrence rate after mitomycin C and beta irradiation was 8.74% and 23.0% of eyes, respectively, after mean follow up of 17.9 and 31.2 months, respectively. The Kaplan-Meier survival analysis revealed a significantly better outcome for those who had intraoperative mitomycin C (Mantel-Cox log rank analysis, p=0.031). The mean interval to recurrence was not significantly different between the two groups. During the follow up, none of the patients showed side effects or reactions related to mitomycin C or beta irradiation.

CONCLUSIONS

The intraoperative administration of 0.04% mitomycin C is more effective than beta irradiation as an adjunctive treatment for pterygium surgery in the patient population examined in this study.

The analgesic effect profile of FR122047, a selective cyclooxygenase-1 inhibitor, in chemical nociceptive models

The pharmacological profile of the analgesic agent, 1-[(4, 5-bis(4-methoxyphenyl)-2-thiazoyl)carbonyl]-4-methylpiperazine hydrochloride (FR122047), was investigated. In recombinant human cyclooxygenase enzyme assays, the inhibition of prostaglandin E(2) formation by FR122047 was 2300 times more selective for cyclooxygenase-1 than cyclooxygenase-2. Oral administration of FR122047 (3.2-100 mg/kg) dose dependently reduced the phase 2 response (10-60 min) of the formalin test in rats. This effect was 3 times less potent than that of indomethacin. FR122047 (1-32 mg/kg; p. o.) showed a dose-dependent analgesic effect against the acetic acid-induced writhing response in mice. Furthermore, FR122047 (0. 01-10 mg/kg, p.o.) inhibited the increase in 6-keto prostaglandin F(1alpha) level in acetic acid-injected mouse peritoneal cavity. However, a selective cyclooxygenase-2 inhibitor, NS-398, had no effect in these cyclooxygenase-1 sensitive pain models. These results suggest that FR122047, a selective cyclooxygenase-1 inhibitor, shows an analgesic effect in chemical nociceptive models and may be a useful analgesic agent.

16S-23S rDNA spacer of Pectinatus, Selenomonas and Zymophilus reveal new phylogenetic relationships between these genera

The 16S-23S rDNA spacer regions of two Pectinatus species, two Zymophilus species and one Selenomonas species were cloned after PCR amplification. The results of PCR amplification showed that these species had two types of spacer regions which differ in molecular size (long and short). Only the long spacer regions in these bacteria contained one or two tRNA genes (alanine and/or isoleucine). The spacer regions in these bacteria had a relatively high level of homology. Homology was particularly high for bacteria belonging to the same genus. Interestingly, the order of the two tRNA genes present in the long spacer regions of Pectinatus and Selenomonas was the reverse of that which had been previously reported for other bacteria. The results of spacer homology analysis and the order of the tRNA genes suggest that the taxonomic classification of anaerobic bacteria isolated from the brewing process should be re-examined.

In vitro antiplatelet profile of FR171113, a novel non-peptide thrombin receptor antagonist

Synthetic peptides (5 to 14 amino acids), identical in sequence to the new amino-terminus of the thrombin receptor generated following cleavage by thrombin, act as thrombin receptor agonist peptides. Whilst thrombin receptor antagonist peptides are known, non-peptide thrombin receptor antagonists have yet to be described. In the present study, we compared the antiplatelet effects of 3-(4-chlorophenyl)-2-(2,4-dichlorobenzoylimino)-5-(methoxycarbonyl methylene)-1,3-thiazolidin-4-one (FR171113), a novel non-peptide thrombin receptor antagonist, with the known thrombin receptor antagonist 3-mercapto-propionyl-Phe-Cha-Cha-Arg-Asn-Pro-Asn-Asp-Lys-Tyr-OH (C186-65), and argatroban, a specific protease inhibitor of thrombin. FR171113 and C186-65 inhibited thrombin-induced platelet aggregation (IC(50)=0.29 microM and 15 microM, respectively) and Ser-Phe-Leu-Leu-Arg-Asn-NH(2) [a synthetic thrombin receptor agonist peptide (TRAP-6)] induced platelet aggregation (0.15 microM and 20 microM, respectively) in human washed platelets. Argatroban potently inhibited thrombin-induced platelet aggregation (IC(50)=3.5 nM), but did not inhibit TRAP-6-induced aggregation even at 100 microM. In contrast, these compounds did not show inhibitory effects on ADP- and collagen-induced aggregation in human platelet-rich plasma even at 100 microM. FR171113 caused a parallel shift to the right of the concentration-response curve describing aggregation induced by TRAP-6. The Schild plot of the data had a slope of -0.840 (r=0.98) and the pA(2) was 7.29. In protease activity studies using a chromogenic substrate, argatroban inhibited thrombin protease activity in a dose-dependent manner, whereas FR171113 and C186-65 were inactive, even at 100 microM. Additionally, only argatroban displayed dose-dependent prolongation of thrombin time, activated partial thromboplastin time and prothrombin time. FR171113 and C186-65 showed no effects, even at a concentration of 100 microM. These results suggest that FR171113 has a similar mode of action to C186-65, but with more potent antiplatelet activity. In conclusion, FR171113 is suggested to be the first example of a non-peptide thrombin receptor antagonist.

Synthesis and biological activity of 4-methyl-3,5-dioxane derivatives as thromboxane A2 receptor antagonists

The synthesis and biological activity of novel 4-methyl-3,5-dioxane analogues are described. All compounds were produced through modification of the substituent formally corresponding to the omega-octenol side chain of thromboxane A2 (TXA2), in reference to the structure of SQ29548. Several compounds were found to be potent TXA2 receptor antagonists. Compound 8b was the most effective inhibitor of 9,11-epoxymethano PGH2 (U-46619)-induced human platelet aggregation (IC50 = 7.4 nM).

Antinociceptive properties of FR140423 mediated through spinal delta-, but not mu- and kappa-, opioid receptors

We investigated the antinociceptive effect of FR140423, 3-(difluoromethyl)-1-(4-methoxyphenyl)-5-[4-(methylsulfinyl)phenyl] pyrazole, in the tail-pinch test in mice, and evaluated the mechanism of action using various opioid receptor antagonists. P.o. and i.t. injection of FR140423 exerted dose-dependent antinociceptive activities with ED50 values of 21 mg/kg and 3.1 microg/mouse, respectively. However, i.c.v. injection of FR140423 did not show an antinociceptive effect. The antinociceptive effects of FR140423 were completely abolished by naloxone and naltrindole but not by naloxonazine, beta-funaltrexamine and nor-binaltorphimine. FR140423 did not affect any opioid receptor binding in mouse spinal membranes at concentrations up to 100 microM in vitro. Naloxone-induced jumping and diarrhea tests for morphine-like physical dependence of FR140423 gave negative results. These results suggest that FR140423 can induce antinociception by acting on the spinal but not the supraspinal site, and that spinal delta-opioid systems indirectly play a role in the antinociception produced by FR140423 in mice.

The profile of FR140423, a novel anti-inflammatory compound, in yeast-induced rat hyperalgesia

The mechanism of action of FR140423 (3-(difluoromethyl)-1-(4-methoxyphenyl)-5-[4-(methylsulfinyl)phenyl]pyra zole), a novel anti-inflammatory compound, in a rat yeast-induced hyperalgesic model was investigated and compared with those of indomethacin and morphine. We tested the inhibitory effects of FR140423 on the formation of arachidonic acid metabolites, prostaglandin (PG) E2, thromboxane (TX) B2 and leukotriene (LT) B4, in yeast-injected inflamed paws and the effect of the opioid receptor antagonist naloxone on FR140423-induced anti-hyperalgesic effect and inhibition of the formation of arachidonic acid metabolites. Oral administration of FR140423 showed a dose-dependent anti-hyperalgesic effect. This effect was fourfold more potent than that of indomethacin but less potent than that of morphine. Unlike morphine, FR140423 suppressed the levels of PGE2 and TXB2 but not LTB4 in inflamed paws. FR140423 did not inhibit yeast-induced paw edema. The anti-hyperalgesic effect of FR140423 in yeast-injected rat paws was partially blocked by naloxone. However, the inhibitory effects of FR140423 on the formation of PGE2 and TXB2 in yeast-injected rat paws were not antagonized by naloxone. These results suggest that FR140423 shows a potent anti-hyperalgesic effect mediated by inhibition of PGs in inflamed tissue and by activation of opioid receptors.

[Brain surface clear cell ependymoma: case report]

We report a case of brain surface clear cell ependymoma. A 13-year-old boy presented with complaints of right hypesthesia. Computed tomography and magnetic resonance image showed a left fronto-parietal cystic, calcified mass lesion. He underwent total resection of the tumor including cyst wall. The tumor located on the surface of the parietal lobe was sharply demarcated from the surrounding brain tissue and there was no continuity with the ventricular wall. Histological examination of the surgical specimens showed oligodendroglioma-like cells that had round unclei, clear cytoplasm which formed perivascular pseudorosettes, and immunoreactivity for glial fibrillary acidic protein (GFAP). Electromicroscopically, microvilli were seen. The findings were compatible with clear cell ependymoma. The cyst wall was lined with a layer of single cuboidal cells and, immunohistochemically, had no basal membrane. The inner surface of the cyst was positive for EMA, and the cuboidal cells were positive for GFAP. We discuss possible mechanisms for tumor growth in our case and the histogenesis of its cyst.

Ventral T-1 neurinoma removed via hemilaminectomy without costotransversectomy--case report

A 39-year-old male presented with a spinal neurinoma originating from the T-1 anterior root and located ventral to the spinal cord. The tumor was removed by hemilaminectomy with only partial facetectomy without costotransversectomy. No stabilization was necessary, and no complications secondary to surgery occurred. Costotransversectomy is not necessary for neurinoma ventral to the spinal cord within the spinal canal at T-1 level because the transverse process protrudes more laterally and the spinal canal of the T-1 vertebra is wider than at other thoracic levels.

Possible inhibitory mechanism of FK506 (tacrolimus hydrate) ointment for atopic dermatitis based on animal models

The effects of FK506 (tacrolimus hydrate) ointment on cutaneous allergic reactions in mice and rats were investigated. FK506 ointment showed significant suppressive effects on delayed allergic reactions in both species, and especially in rats, its inhibitory action was much stronger than that of alclometasone dipropionate, a so-called medium class steroid ointment. On the other hand, FK506 ointment did not inhibit the immediate allergic reaction in rats. FK506 ointment suppressed the delayed allergic reactions in locally passively sensitized mice to the same degree as that in actively sensitized mice. Accordingly, it is speculated that FK506 ointment inhibits the activation of sensitized T lymphocytes (Th1 cells) already accumulated in the dermis.

Anesthetic management for pheochromocytoma resection using spinal cord stimulation and intravenous nicardipine--a case report

We have used spinal cord stimulation (SCS), diazepam and nitrous oxide for maintenance of general anesthesia. Blood pressure was maintained by bolus administration of nicardipine for the removal of pheochromocytoma. Both SCS and nicardipine reduced systemic vascular resistance and SCS increased cardiac output. However, neither SCS nor nicardipine could inhibit the release of norepinephrine. SCS proved to be useful as one of anesthetic technique during the removal of pheochromocytoma, and also in the management of postoperative pain and the prevention of complications.

[Bilateral aplasia of the internal carotid artery: a case report]

We report a case of bilateral aplasia of the internal carotid arteries. A 59-year-old man was admitted with generalized convulsions. Computed tomography and magnetic resonance imaging of the head showed normal findings. Three-dimensional computed tomography, angiography, and intra-arterial digital subtraction angiograms showed bilateral aplasia of the internal carotid arteries. The bilateral ophthalmic arteries were filled from the hypoplastic carotid arteries, and the anterior and middle cerebral arteries were filled from the basilar artery via the posterior communicating arteries. Associated with this bilateral aplasia of the internal carotid arteries, intracranial aneurysms and megadolicho-basilar anomaly were reported. Angiography is to be recommended if IC aplasia is suspected.

Augmentation of the inhibitory effect of FK480, a CCK-A receptor antagonist, on pancreatic exocrine secretion by achlorhydria

The effect of intraluminal acid and cholecystokinin (CCK) receptor blockade on the pancreatic secretory response was examined in rats. Blockade of gastric acid secretion by YM022 (CCK-B receptor antagonist) or famotidine (histamine-2 receptor antagonist) resulted in a significant suppression of casein-stimulated pancreatic exocrine secretion as determined by juice volume and amylase secretion. Ligation of the gastric pylorus, which leads to complete prevention of gastric acid from entering the duodenum, also suppressed pancreatic exocrine secretion. FK480 (CCK-A receptor antagonist) inhibited pancreatic exocrine secretion dose dependently at doses of 0.01-1.0 mg/kg. When submaximal doses of FK480 and YM022 were treated concomitantly, pancreatic exocrine secretion was inhibited more profoundly than when treated solely. Hydrochloric acid (HCl; 0.05 N), injected into the duodenum, stimulated pancreatic exocrine secretion to a level comparable to that exhibited by intraduodenal casein. This effect of HCl was inhibited by FK480 (1.0 mg/kg) but not by YM022 (1.0 mg/kg). These findings suggest that inhibition of gastric acid secretion leads to the suppression of pancreatic exocrine secretion through mechanisms mediated by CCK-A receptors.

Comparison of the antithrombotic effects of FK633, GPIIb/IIIa antagonist, and aspirin in a guinea pig thrombosis model

Antiplatelet and antithrombotic effects of FK633 (a GPIIb/IIIa antagonist) and aspirin were compared. FK633 at 0.32 mg/kg i.v. or aspirin at 10 mg/ kg i.v. inhibited ex vivo collagen-induced aggregation by >50% for 1 hour in guinea pigs. However, aspirin was very weak in inhibiting ADP-induced aggregation. In vivo antithrombotic effects of FK633 and aspirin were compared using a FeCl3-induced carotid artery thrombosis model in guinea pigs. Pretreatment with 0.32 mg/kg i.v. of FK633 significantly prevented occlusive thrombus formation, but aspirin at 10 mg/kg i.v. did not. In thrombolysis experiments, adjunctive use of FK633 (0.32 mg/kg i.v.) with rt-PA (0.3 mg/kg bolus+1.0 mg/kg/hr) achieved reperfusion in five of five animals without reocclusion. Aspirin (10O mg/kg i.v.) with rt-PA also achieved reperfusion in three of five animals with high incidence of reocclusion. These results suggest that FK633 may be a more effective antithrombotic agent than aspirin due to its agonist-independent antiplatelet effects.

[Ruptured traumatic aneurysms of the peripheral anterior cerebral artery: study of delayed hemorrhage after closed head injury]

We report three cases of ruptured traumatic aneurysms of the peripheral anterior cerebral artery after closed head injury. These cases were all young men with closed head injury due to traffic accidents. Consciousness level on admission was coma in all three cases. Case 1 was a 19-year-old man with interhemispheric hematoma on initial CT, then 7 days later his consciousness cleared. However, 14 days later he suddenly lapsed into a deep coma with a severe frontal hemorrhage. Case 2 was a 13-year-old boy. Plain skull films demonstrated a frontal depressed fracture, but CT scan showed no bleeding. Four days later his consciousness cleared but 11 days after trauma, he lapsed into a deep coma with a frontal hemorrhage. Case 3 was a 22-year-old man. Initial CT showed a slight ventricular hemorrhage. Fourteen days later, his consciousness had almost cleared, but then he lapsed into a deep coma with a large frontal hemorrhage 11 weeks after the trauma. These patients all died within a few days after intracranial bleeding. All patients underwent cerebral angiography but none of them showed filling defect. Autopsy was performed and ruptured aneurysms were found on the distal anterior cerebral artery that had no relation to the branch of bifurcation. Histological examination demonstrated a lack of elastic lamina and media in all of these three cases, so each of them was a victim of so-called false aneurysm. Twenty reported cases of ruptured traumatic aneurysms of the peripheral cerebral artery with delayed hemorrhage after closed head injury were reviewed. Factors in the traumatic aneurysm showed no relation to the duration of disturbed consciousness. Within one month, delayed hemorrhage due to ruptured traumatic aneurysm occurred. None of the delayed hemorrhages involved subarachnoid hemorrhage. Subdural hematoma was seen in the distal middle cerebral artery and frontal hemorrhage was found in the distal anterior cerebral artery. We consider that frontal hemorrhage is a predictive finding for the type of delayed hemorrhage due to traumatic aneurysm in the distal anterior cerebral artery.

Effects of growth temperature on the fatty acid composition of the free-living nematode Caenorhabditis elegans

The effects of growth temperature on the fatty acid compositions of the phosphatidylcholine (PC), phosphatidylethanolamine (PE), and total lipid (TL) fractions of the free-living nematode Caenorhabditis elegans were investigated. A reduction in growth temperature from 25 to 15 degrees C caused the proportions of eicosapentaenoic acid (20:5n-3) to increase from 23.6 to 32.5% in the PC, from 7.4 to 10.8% in the PE, and from 12.9 to 19.9% in the TL fractions. Conversely, the levels of dihomo-gamma-linolenic acid (20:3n-6) and arachidonic acid (20:4n-6) in these phospholipid fractions and the TL fraction both decreased with decreasing growth temperature. Analysis of the positional distribution of fatty acids in the PC fraction revealed that the change in the composition of C20 polyunsaturated fatty acid was obvious in position sn-2. Lowering the growth temperature induced an increase in the level of the diacyl subclass of PE from 58% at 25 degrees C to 71% at 15 degrees C, with a concomitant decrease in the levels of the alkylacyl and alkenylacyl subclass of PE of C. elegans. These changes observed in the phospholipids of C. elegans might be one mechanism for adaptation to low temperature.

Pentamidine is a specific, non-peptide, GPIIb/IIIa antagonist

Pentamidine was previously shown to act on glycoprotein (GP) IIb/IIIa (Cox et al., Thromb Haemost 1992; 68: 731). In this paper we study the effect of pentamidine on other RGD-dependent receptors. In a cell adhesion assay, pentamidine was 500 times more potent than RGDS at inhibiting platelet adhesion to fibrinogen. While RGDS inhibited platelet adhesion to fibronectin, endothelial cell adhesion to vitronectin or fibronectin, 293 cell adhesion to vitronectin, IMR 32 cell adhesion to fibronectin and C32 cell adhesion to vitronectin; pentamidine failed to inhibit these interactions at doses as high as 1 mM. Resting platelets fixed in the presence of 1 mM RGDS had increased binding of fibrinogen, i.e., RGDS activated GPIIb/IIIa, while pentamidine at 100 microM had no effect. Similarly, RGDS induced the binding of an anti-LIBS monoclonal antibody, while pentamidine had no effect. Pentamidine partially, but significantly, inhibited lysosome and alpha-granule release induced by the thrombin agonist peptide, while RGDS had no effect. Neither pentamidine nor RGDS affected ADP-induced Ca2+ influx. Pentamidine had no effect on ADP-induced intracellular pH changes while RGDS prevented the pH from returning to normal. Thus, pentamidine is a non-peptide GPIIb/IIIa antagonist that is non-activating and is specific for GPIIb/IIIa.

The anti-platelet and anti-thrombotic effects of FK633, a peptide-mimetic GPIIB/IIIA antagonist

The anti-platelet and anti-thrombotic properties of FK633, a peptide mimetic GPIIb/IIIa antagonist were studied. In human platelet rich plasma, FK633 inhibited ADP-, collagen-, thrombin-, and PAF-induced platelet aggregation with IC50 values of 103, 87, 98, and 239 nM, respectively. RGDS acted similarly, but it's potency was about 1,000 times weaker than FK633, FK633 inhibited 125I-fibrinogen binding to human washed platelet with an IC50 of 88 nM. FK633 did not inhibit alphavbeta3, alpha5beta1, and alphavbeta1 integrin-mediated cellular adhesion up to 1.0mM, while RGDS inhibited all these interactions. In dogs, bolus injection of FK633 at 0.1 mg/kg significantly suppressed ex vivo ADP-induced platelet aggregation (>40% inhibition) and thrombus formation at stenosed and injured coronary artery, but did not prolong template bleeding time. However, FK633 inhibited >90% ADP-induced aggregation at 0.32 mg/kg, causing significant prolongation of the bleeding time. Thus, FK633 is a specific GPIIb/IIIa antagonist with potent anti-thrombotic effect in vivo, but careful dosing study might be necessary to avoid the bleeding complications in the clinic.

FK409, a new nitric-oxide donor, suppresses smooth muscle proliferation in the rat model of balloon angioplasty

The effect of FK409, a new nitric-oxide (NO) donor, on neointimal formation of rat carotid arteries following balloon injury was studied. The intimal thickening at 14 days was strongly suppressed by twice daily administration of FK409 at 10 mg/kg from 2 days before to 13 days after injury. The neointima area and neointima/media ratio were decreased by 48.0% (P < 0.01) and 38.5% (P < 0.01), respectively, compared with control. On the other hand, isosorbide dinitrate (ISDN), a classical nitro-vasodilator, did not suppress intimal thickening even at 100 mg/kg twice a day. An in vivo 5-bromo-2'-dedoxyuridine (BrdU) uptake study revealed that FK409 inhibited the proliferative response of smooth muscle cells (SMC) in media at early stage of injury. In fact, the neointimal formation at 14 days was inhibited by the short term administration of FK409 only from the day of injury to 4 days after at 10 mg/kg twice a day. In cultured rat SMC, FK409 (1-10 mumol/l) markedly enhanced intracellular c-GMP and inhibited the proliferation in 10% FBS-containing medium. These results suggest that FK409 suppresses intimal thickening following balloon injury of the rat carotid artery by inhibition of SMC proliferation.

Automated measurement of alpha-amylase isoenzymes with 6(3)-deoxymaltotriose as selective amylase inhibitor

We developed an automated method for measurement of alpha-amylase isoenzymes in serum by a single kinetic assay (SKA) and a double kinetic assay (DKA) with 2-chloro-4-nitrophenyl-6(5)-azido-6(5)-deoxy-beta-maltopentaoside as a substrate and 6(3)-deoxymaltotriose (DOG3) as a novel selective amylase inhibitor. DOG3 showed a large difference in inhibitory activity between human pancreatic alpha-amylase (HPA; 86.9% inhibition) and salivary alpha-amylase (32.1% inhibition) at 0.33 mmol/L. Constant inhibition was obtained immediately after addition of DOG3. The inhibitory effect did not change with variation in concentrations of amylase up to approximately 3000 U/L. The results obtained by SKA correlated well with those obtained by three methods: monoclonal antibody (r = 0.988), wheat germ inhibitor (r = 0.989), and DKA (r = 0.995). The within-run and between-run CVs for HPA were 0.63-2.32% on SKA, 0.69-1.81% on DKA. No significant interferences by endogenous serum compounds were observed with the proposed methods.

Automated measurement of alpha-amylase isoenzymes with 6(3)-deoxymaltotriose as selective amylase inhibitor

We developed an automated method for measurement of alpha-amylase isoenzymes in serum by a single kinetic assay (SKA) and a double kinetic assay (DKA) with 2-chloro-4-nitrophenyl-6(5)-azido-6(5)-deoxy-beta-maltopentaoside as a substrate and 6(3)-deoxymaltotriose (DOG3) as a novel selective amylase inhibitor. DOG3 showed a large difference in inhibitory activity between human pancreatic alpha-amylase (HPA; 86.9% inhibition) and salivary alpha-amylase (32.1% inhibition) at 0.33 mmol/L. Constant inhibition was obtained immediately after addition of DOG3. The inhibitory effect did not change with variation in concentrations of amylase up to approximately 3000 U/L. The results obtained by SKA correlated well with those obtained by three methods: monoclonal antibody (r = 0.988), wheat germ inhibitor (r = 0.989), and DKA (r = 0.995). The within-run and between-run CVs for HPA were 0.63-2.32% on SKA, 0.69-1.81% on DKA. No significant interferences by endogenous serum compounds were observed with the proposed methods.

Effect of TFC-612, a 7-thia prostaglandin E1 derivative, on a peripheral arterial occlusive disease model in rats

TFC-612, methyl 6-[((1R,2S,3R)-3-hydroxy-2-[(1E,3S,5R)-3-hydroxy-5- methyl-1-nonenyl)-5-oxocyclopentyl]-thio]-hexanoate, inhibited the progression of the lesion in a lauric acid-induced peripheral arterial occlusive model at 1.0 mg/kg p.o. or 1.0 microgram/rat/h s.c. in rats. Aspirin (32 mg/kg, p.o.), an anti-platelet drug, did not suppress the lesion growth. On the other hand, ketanserin (10 mg/kg, p.o.), a 5-HT2 antagonist, also inhibited the progression of the lesion. In vitro, TFC-612 inhibited rat platelet aggregation induced by collagen and ADP with IC50 values of 5.4 ng/mL and 9.5 ng/mL, respectively. Aspirin also inhibited collagen-induced aggregation with an IC50 value of 6.3 micrograms/mL, but not ADP-induced aggregation at 180 micrograms/mL. Ketanserin had no effect on either aggregation at 40 micrograms/mL. In ex vivo experiments, aspirin inhibited platelet aggregation induced by collagen at 10 and 32 mg/kg in rats. However, TFC-612 showed significant inhibition only at 10 mg/kg. TFC-612 and ketanserin increased dermal blood flow in the rat paw at 1.0 microgram/kg i.v. and 100 micrograms/kg i.v., respectively. Aspirin had no effect on blood flow at 3.2 mg/kg i.v. These results suggest that the improvement of microcirculation, in addition to anti-platelet action by TFC-612, contributes to its inhibitory effect in a peripheral arterial occlusive model in rats.

Studies on anti-platelet agents. IV. A series of 2-substituted 4,5-bis(4-methoxyphenyl)pyrimidines as novel anti-platelet agents

The syntheses and structure-activity relationships of a series of 2-substituted 4,5-bis(4-methoxyphenyl)pyrimidines, designed on the basis of structural analyses of several cyclooxygenase (CO) inhibitors, and their derivatives as anti-platelet agents based on CO inhibition are described. Among them, 4,5-bis(4-methoxyphenyl)-2-morpholinopyrimidine (8) and 4,5-bis(4-methoxyphenyl)-2-(3,5-dimethylmorpholin-4-yl)pyrimidine (9) showed potent inhibitory activity on malondialdehyde, formed by the CO-catalyzed oxygenation of arachidonic acid (A.A.) in prostanoids, production in vitro (73.4% inhibition at 10(-8) M and IC50 = 1.4 x 10(-8) M, respectively). Certain compounds were also examined in ex vivo studies. Of these compounds, 4,5-bis(4-methoxyphenyl)-2-(1-methyl-1,2,3,6-tetrahydropyrid-4-yl) pyrimidine (11a) exhibited potent and long-lasting anti-platelet activity ex vivo, that is, 11a showed 97% inhibition of platelet aggregation induced by A.A. even 24h after oral administration of 3.2 mg/kg in guinea pigs, and 60-70% inhibition at 6 h after lower doses (1.0 mg/kg). The ex vivo activity of 11a is more than three times that of aspirin (aspirin showed 81% inhibitory activity on platelet aggregation induced by A. A. at 6 h after oral administration at 10 mg/kg in this study). Compound 11a also showed vasodilatory activity (ED50 = 5.3 x 10(-6) M, while aspirin has no vasodilatory activity at 6.0 x 10(-4) M).

Studies on anti-platelet agents. V. Synthesis and structure-activity relationship of 3-substituted 5,6-bis(4-methoxyphenyl)-1,2,4-triazines

The syntheses and structure-activity relationships of a series of 3-substituted 5,6-bis(4-methoxyphenyl)-1,2,4-triazines as anti-platelet agents based on cyclooxygenase (CO) inhibition are described. Of these compounds, 1-[5,6-bis(4-methoxyphenyl)-1,2,4-triazin-3-yl]carbonyl-4-methylpi perazine (10) exhibited potent CO inhibition in vitro (IC50 = 2.8 x 10(-7) M) with vasodilatory activity (ED50 = 4.5 x 10(-5) M). Compound 10 also showed potent ex vivo activities, completely preventing platelet aggregation induced by arachidonic acid and collagen at 6 h after oral administration of 3.2 and 1.0 mg/kg. The ex vivo potency of 10 is more than three times that of aspirin. Moreover, 10 demonstrated no gastrointestinal side effect in rats even at 100 mg/kg in spite of its potent CO inhibition activity, while aspirin, the most widely-used anti-platelet drug, showed gastrointestinal side effects in a dose-dependent manner (32, 100, and 320 mg/kg) in our study. These results suggested that 10 is a very attractive candidate for development as an anti-platelet drug since an aspirin-like anti-platelet agent, based on CO inhibition and being free from gastrointestinal side effects, is a major goal of thromboembolic research.

Effect of TFC-612, a 7-thia prostaglandin E1 derivative, on intimal thickening after endothelial injury with balloon catheter in rats

The effect of TFC-612, methyl-6-[(1R,2S,3R)-hydroxy-2-](1E,3S,5R)-3- hydroxy-5-methyl-1-nonenyl]-5-oxocyclopentyl)thio] hexanoate, on intimal thickening of carotid artery 14 days after endothelium denudation with a balloon catheter was examined in rats. This compound significantly suppressed the neointimal area and the ratio of intimal and medial layer by 41.1% and 31.4%, respectively, at 3.2 micrograms/rat/h s.c. infusion. At this dose, this compound did not inhibit platelet aggregation induced by either collagen or ADP. It did not inhibit bromodeoxyuridine incorporation into medial smooth muscle cells at 3 days after injury. In in vitro experiments, TFC-612 did not inhibit the [3H]thymidine uptake into cultured smooth muscle cells, but it showed significant inhibition of smooth muscle cell migration induced by platelet-derived growth factor (PDGF) at more than 10(-9) M. This compound increased cyclic AMP levels dose dependently in cultured smooth muscle cells at more than 10(-8) M. These results suggest that TFC-612 inhibits intimal thickening by inhibition of smooth muscle cell migration from media to intima through cyclic AMP elevation.

Antiplatelet agents based on cyclooxygenase inhibition without ulcerogenesis. Evaluation and synthesis of 4,5-bis(4-methoxyphenyl)-2-substituted-thiazoles

The syntheses, biological evaluations, and structure-activity relationships of a series of 4,5-bis-(4-methoxyphenyl)-2-substituted-thiazoles as potent antiplatelet agents with vasodilatory activity are described. 2-Guanidino-4,5-bis(4-methoxyphenyl)thiazole (3), designed from two parent compounds (itazigrel and timegadine), showed inhibitory activity of malondialdehyde (MDA, IC50 = 31 microM) production which is formed from the cyclooxygenase (CO)-catalyzed oxygenation of arachidonic acid in the synthesis of prostanoids in platelets, with vasodilatory activity (ED50 = 2.0 microM). Further structure-activity relationship studies on 3 culminated in the preparation of 4,5-bis(4-methoxyphenyl)-2-[(1-methylpiperazin-4-yl)carbonyl]thiaz ole (10a, FR122047) which exhibited potent inhibitory activity on MDA synthesis in vitro (IC50 = 0.088 microM) and platelet aggregation in guinea pigs ex vivo (100% inhibition even 6 h after 1.0 mg/kg administration) with vasodilatory activity in vitro (ED50 = 6.2 microM). Moreover, 10a demonstrated no ulcerogenesis effect in rats even at 100 mg/kg dosage (safety margin in rats is more than 70 while that of aspirin is only 1.2) in spite of its potent CO inhibition (IC50 = 0.43 microM14), while the use of aspirin, a CO inhibitor and the most popular thromboembolic drug, is restricted by the side effect. Pharmacokinetic studies on 10a have revealed that 10a is detectable in platelet-rich plasma but not in platelet-poor plasma 1 day after oral administration, which indicates that 10a tends to be localized in platelets. This property could be responsible for its low toxicity and reduction of side effects in clinical studies.

Studies on anti-platelet agents. II. Synthesis and platelet-inhibitory activity of 5-methyl-4-(3-pyridyl)-2-(substituted benzimidazol-5-yl)imidazoles

A series of 5-methyl-4-(3-pyridyl)-2-(substituted benzimidazol-5-yl)imidazole derivatives was synthesized and tested for anti-platelet and vasodilatory activities. Some compounds were found to have potent activities and low acute toxicity. In particular, 5-methyl-4-(3-pyridyl)-2-(7-chloro-6-methoxy-2- methylbenzimidazol-5-yl)imidazole (26) and 5-methyl-4-(3-pyridyl)-2-(7-chloro-3-methoxy-2-methylbenzimidazol- 5-yl)imidazole (33) exhibited 63% or 51% inhibition at a dose of 10 mg/kg for anti-patelet activity ex vivo in rats, respectively, while they showed no toxicity even at 180 or 100 mg/kg, respectively. Compound 33 also exhibited potent vasodilatory activity (ED50 = 11 micrograms/ml). Enzyme studies on these imidazoles showed that the novel imidazoles inhibit some enzymes which are involved in the platelet aggregation cascade such as cyclooxygenase, phosphodiesterase (PDE), and thromboxane A2 synthetase. The enzyme assay also suggested that the inhibitory activity on PDE may account for the vasodilatory activity of these imidazoles.

[Increased [3H] PN 200-110 binding sites in the myocardial sarcolemmal membrane in endotoxin shock rats]

To study the effects of endotoxin shock on calcium channels of sarcolemma, we investigated the characteristics of binding of a radioligand, [3H] PN 200-110 (PN), to relatively pure sarcolemmal membrane (SL) from the heart of endotoxin shock rats. The rats were induced into endotoxin shock with the cecal ligation and puncture. The SL of the early group (EG), in hyperdynamic stage, was isolated from the rat's heart, 9 hours after the procedure, and that of late group (LG), in hypodynamic stage, was isolated from the rat's heart, 18 hours after the procedure. Binding of PN to SL of EG was 31-37% greater than to SL of the sham operated rat (CG), while binding of PN to SL of LG was not raised significantly, as compared to that to CG. The maximum number of PN binding sites (Bmax) was 35% higher in SL of EG than in SL of CG, but there was no significant difference between Bmax in SL of LG and CG. On the other hand, the affinity for PN binding (KD) was similar in all three groups. Since PN binding sites are considered to be specific sites for the voltage-dependent Ca2+ channels of sarcolemma, it is concluded that the density of these channels in the sarcolemma of rat increases during the early stage of endotoxin shock and decreases to control level in the late stage of the shock.

The anti-platelet actions of FR122047, a novel cyclooxygenase inhibitor

The anti-platelet actions of 1-[(4,5-bis(4-methoxyphenyl)-2- thiazoyl)carbonyl]-4-methylpiperazine hydrochloride (FR122047) were investigated in vitro and in vivo. FR122047 was 100 times more potent than aspirin against arachidonic acid- and collagen-induced human and guinea-pig platelet aggregation in vitro. Its actions on platelets were a result of cyclooxygenase inhibition. The single oral dose of FR122047 inhibited arachidonic acid- and collagen-induced aggregation with an ED50 of 280 micrograms/kg and 530 micrograms/kg, respectively, in guinea-pigs. The anti-platelet action was augmented 5-10 times by repeated administration for 4 days. At 1 mg/kg the inhibitory actions were prolonged for 48 h and the drug concentration was < 0.1 ng/ml in platelet-poor plasma at 24 h and 0.282 ng/ml in platelet-rich plasma at 48 h. The safety margin in rats (minimum ulcerogenic dose/ED50 for anti-platelet aggregation) of FR122047 was more than 70, while that of aspirin was only 1.2. These results indicate that FR122047 is concentrated in platelets and may be a useful anti-platelet agent.

Pentamidine: a non-peptide GPIIb/IIIa antagonist--in vitro studies on platelets from humans and other species

In this paper we show that the non-peptide anti-parasite agent pentamidine is a broad spectrum anti-platelet agent with an IC50 of 1.1 microM in ADP-induced platelet aggregation in human platelet rich plasma (PRP). It had similar activity when collagen, arachidonic acid, platelet activating factor, thrombin and epinephrine were used. It had no effect on platelet intracellular cAMP levels. It inhibited 125I-fibrinogen, 125I-fibronectin and 125I-von Willebrand factor binding to ADP-activated fixed platelets with IC50 values of 160, 160 and 60 nM respectively. Pentamidine showed a high degree of species selectivity with slightly less activity in monkey and dog PRP and little activity in guinea pig, rabbit, rat and mouse PRP compared with human. This was similar to the other RGD analogues tested. This species specificity was shown to be dependent on the species of platelets and independent of the species of fibrinogen. Thus, pentamidine is a potent non-peptide inhibitor of fibrinogen binding to GPIIb/IIIa.

Studies on antiplatelet agents. I. Synthesis and platelet inhibitory activity of 5-alkyl-2-aryl-4-pyridylimidazoles

5-Alkyl-2-aryl-4-pyridylimidazoles were synthesized and tested in rat ex vivo platelet aggregation studies. Among these compounds, 2-(2-fluorophenyl)-5-methyl-4-(3-pyridyl)imidazole (25) was most potent, and showed 98% inhibition at a dose of 10 mg/kg (p.o.). 25 had inhibitory activity on cyclooxygenase, thromboxane A2 (TXA2) synthetase, and phosphodiesterase, and also showed inhibited KCl-induced contraction of rat aorta. All compounds have little acute toxicity and appear to be free of adverse effects on the stomach.

TFC-612, a prostaglandin E1 derivative, enhances fibrinolytic activity in rats

TFC-612 inhibited thrombus formation on wire coils inserted into the lumen of the inferior vena cava of rats after 5 oral doses of 1.0 and 3.2 mg/kg and subcutaneous doses of 1.0 and 3.2 micrograms/rat/hr. This compound showed slight inhibition of platelet aggregation induced by collagen at 1.0 and 3.2 mg/kg (po) and significant inhibition at 10 mg/kg. TFC-612 had no effect on the plasma coagulation system at 3.2 mg/kg. Conversely, oral doses of 0.32-3.2 mg/kg dose- dependently enhanced fibrinolytic activity as measured by euglobulin clot lysis time and lysis area on fibrin plates by euglobulin fraction. TFC-612 did not enhance fibrinolytic activity in vitro. These results suggest that the enhancement of fibrinolytic activity by TFC-612, which may be due to an increase in tissue plasminogen activator release or reduction of plasminogen activator inhibitors release, contributes to its inhibition of thrombus formation.