Changes in respiratory physiological dead space and compliance during non-abdominal, upper abdominal and lower abdominal surgery under general anaesthesia

BACKGROUND AND OBJECTIVE

To evaluate the temporal changes in respiratory physiological dead space and dynamic compliance of the respiratory system during non-abdominal, upper abdominal and lower abdominal surgery under general anaesthesia with intermittent positive pressure ventilation.

METHODS

Thirty-four adult patients were studied (non-abdominal surgery, n = 8; upper abdominal surgery, n = 13 and lower abdominal surgery in lithotomy position, n = 13). Physiological dead space was measured using the single breath carbon dioxide test. The physiological dead space to tidal volume ratio (VD/VT), dynamic compliance of respiratory system, expiratory tidal volume and respiratory rate were measured 10 min after tracheal intubation, and 30, 60 and 120 min later.

RESULTS

In lower abdominal surgery group, VD/VT was significantly increased at 120 min compared with 0 min (P = 0.005) and 30 min (P = 0.009). There were no significant differences in VD/VT between the three groups at any time point. Compliance decreased significantly in patients with upper abdominal (120 min) and lower abdominal surgery (60 and 120 min), but there were no significant changes during non-abdominal surgery.

CONCLUSIONS

We found that the VD/VT increased in patients undergoing lower abdominal surgery in lithotomy and head down tilt, and compliance decreased in those undergoing upper abdominal and lower abdominal surgery over time.

Modes of hantavirus transmission in a population of Clethrionomys rufocanus bedfordiae inferred from mitochondrial and microsatellite DNA analyses

To elucidate the mode of transmission of Puumala-related hantavirus in a population of gray red-backed voles, Clethrionomys rufocanus bedfordiae, in Hokkaido, Japan, we analyzed the kin structure and dispersal patterns of individual voles using microsatellite and mitochondrial DNA markers. Siblings or dam/offsprings was identified within the population based on the relatedness calculation with the microsatellite data. The pairwise relatedness values obtained could reveal kinship among all vole individuals within the population. Based on the assessment of kinship, we did not find a positive relationship between hantavirus transmission and close kinship. Males infected with the hantavirus carried a relatively uncommon mitochondrial haplotype. However, these infected males shared low relatedness values and were not considered closely related, i.e., they were not siblings or parent/offspring. These observations imply that hantavirus transmission in the vole population may not be related to close kinship but by random horizontal infection.

Synthesis of Seoul virus RNA and structural proteins in cultured cells

Seoul virus is a hantavirus that causes hemorrhagic fever with renal syndrome (HFRS). The virion has a tripartite (S, M, and L) negative-stranded RNA genome, which is characteristic of the family Bunyaviridae. However, the molecular basis of virus replication is not well known. We established a Northern blot hybridization (NB) procedure using digoxygenin-labeled RNA probes, to quantitate the hantaviral plus- and minus-strand RNAs separately. Virus RNA replication was analyzed in infected Vero E6 cells. When the Vero E6 cells were infected with Seoul virus strain KI-83-262 (KI) at m.o.i. = 0.25, the plus-strand RNA was detected within 1 h post-infection (hpi), and the minus-strand RNA was detected subsequently. Using laser confocal microscopy, the nucleocapsid protein (NP) was detected within 2 hpi, and accumulated as scattered granules in the cytoplasm until 24 hpi. In contrast, the G2 protein first appeared at 8 hpi, was immediately transported to the Golgi, and accumulated in the Golgi until 24 hpi. Infectious virus particles were released into the medium at 24 h hpi. These findings indicate that hantavirus RNA replication starts with the appearance of NP at 2 hpi, glycoproteins then accumulate gradually in the Golgi, and virion formation is initiated once the viral RNAs and proteins have accumulated.

A continuing high incidence of subacute sclerosing panencephalitis (SSPE) in the Eastern Highlands of Papua New Guinea

The aims of this descriptive study were to confirm the high incidence of subacute sclerosing panencephalitis (SSPE) previously reported from Papua New Guinea (PNG) and to relate SSPE to previous measles vaccination and measles illness. From February 1997 to April 1999 we diagnosed a total of 55 patients with SSPE at Goroka Base General Hospital in Eastern Highlands Province (EHP) of PNG. The diagnosis was based on high cerebrospinal fluid and serum measles virus antibody titres with progressive neurological disorder and myoclonic jerks. Of these 55 patients 42 were from EHP, including 32 whose onset was in the 2-year period 1997-1998. The annual incidence of SSPE in EHP in these 2 years was 98 per million population under 20 years of age, the highest ever reported. This incidence was more than ten times higher than the highest incidence in the prevaccine era reported from elsewhere. The mean age of onset of SSPE was 7.7 years (range 2.8-14.8 years) and the interval between measles and the onset of SSPE, where known, had a mean of 5.9 years and a range of 2.5-11.1 years. Among the SSPE patients 19 had a documented history of measles vaccination. Eight of these 19 also had documentation of previous measles illness; of these, seven were vaccinated after the development of measles and one was vaccinated 20 days before measles illness. Two non-SSPE children received vaccination twice which was documented and subsequently developed measles which was also substantiated by documentation. Two patients with SSPE yielded amplified nucleotide sequences of measles virus that were different from any of the vaccine strains. We found no evidence to implicate measles vaccination in the development of SSPE.

Neuropathological analysis in spinal muscular atrophy type II

We performed a neuropathological analysis, including in situ nick end labeling (ISEL) and immunohistochemistry, of two cases of clinicogenetically confirmed infantile spinal muscular atrophy (SMA) type II. Both cases showed severe reduction of the motor neurons and gliosis in the spinal cord and brain stem, although the occurrences of central chromatolysis and ballooned neurons were not frequent. Clark's and lateral thalamic nuclei, which are usually altered in SMA type I, were spared, whereas Betz cells in the precentral gyrus and large myelinated fibers in the lateral funiculus were reduced in number. Regarding apoptosis, only the younger case demonstrated a few ISEL-positive nuclei in the dorsal horn, with reduced Bcl-x expression level in the Purkinje cells. Unlike SMA type I, the expression of neurofilaments was not disturbed and the reduction in synaptophysin expression level in the anterior horn was mild. An oxidative stress-related product was deposited in atrophic motor neurons in the spinal cord, and neurons with nuclei immunoreactive for 8-hydroxy-2'-deoxyguanosine were found in the lateral thalamus. In contrast, the expression of glial glutamate transporters was not altered. These data suggest that oxidative stress and, to a lesser extent, apoptotic cell death, but not disturbed neurofilament metabolism or excitotoxicity, may be involved in neurodegeneration in SMA type II.

Involvement of the JNK-like protein of the Aedes albopictus mosquito cell line, C6/36, in phagocytosis, endocytosis and infection of West Nile virus

We recently cloned a c-Jun amino-terminal kinase (JNK) sequence from the C6/36 cell line, derived from the mosquito Aedes albopictus. We showed that SP600125, an inhibitor of JNK proteins, inhibits phagocytosis by C6/36 cells, suggesting that the JNK-like protein regulates phagocytosis. Here, we show that C6/36 cells constitutively express low levels of mRNA encoding the antibacterial peptides, cecropin and defensin, but that these mRNAs were up-regulated upon stimulation by lipopolysaccharide (LPS). Thus, the C6/36 cells have properties similar to those of mammalian macrophages. To characterize further the functional properties of C6/36 cells, we have assayed the role of the JNK-like protein in phagocytosis, endocytosis, and viral infection. C6/36 cells phagocytosed bacteria and artificial beads, and this was only slightly up-regulated following LPS stimulation, suggesting that newly stimulated JNK-like protein was not necessary for phagocytosis. SP600125 inhibited the acidification of intracellular compartments, including those involved in the endocytic pathway. Pretreatment of C6/36 cells with SP600125 or bafilomycin A1, but not cytochalasin D, inhibited the entry of West Nile virus (WNV), suggesting that WNV is internalized mainly by endocytosis, and that the JNK signalling pathway is important for endocytic entry. These findings indicate that the JNK-like protein regulates basic physiological functions, including phagocytosis and endocytosis and infection of WNV.

Molecular breeding of transgenic rice expressing a xylanase domain of the xynA gene from Clostridium thermocellum

The gene encoding the catalytic domain of thermostable xylanase from Clostridium thermocellum F1 was expressed in rice plants under the control of a constitutive promoter. The gene encoding Xylanase A was modified to encode the catalytic domain of family 11 xylanase without the signal sequence (xynA1), and was introduced into rice plants and expressed under the control of a modified cauliflower mosaic virus 35S promoter. Zymogram analysis indicated that the recombinant xylanase was produced in rice plants. The xynA1 gene was stably expressed in rice straw and seed grains. No phenotypic effect of xylanase expression was noted. The enzyme was detected in the desiccated grain. High levels of enzyme activity were maintained in the cell-free extract during incubation at 60 degrees C for 24 h. The results indicated that high levels of xylanase can be produced in rice plants.

Evidence of G-A/A-G pair, not A-G/G-A pair, in SECIS element

The decoding of selenocysteine (Sec) codon for selenoprotein translation in animals requires the SECIS (selenocysteine insertion sequence) element in the 3'-untranslated region (3'-UTR) of selenoprotein mRNA. It has been hypothesized that SECIS has G-A/A-G pairs, which are non-Watson-Crick base pairs, and are one of the most indispensable parts for Sec translation. However, DNA structure research has shown that the DNA loop structure was closed by a G-A pair (1), although there is little evidence for G-A stability in SECIS. Our aim was to investigate the existence of a G-A/A-G base pair by electrophoretic mobility and Tm measurement, and we found that G-A/A-G bases formed a stable pair, but A-G/G-A bases did not.

Serological analysis of hemorrhagic fever with renal syndrome (HFRS) patients in Far Eastern Russia and identification of the causative hantavirus genotype

Hemorrhagic fever with renal syndrome (HFRS) is endemic in East Asia and Europe. The disease is caused by several viruses belonging to the genus Hantavirus, including the Hantaan virus (HTNV), Seoul virus (SEOV), Dobrava Belgrade virus (DOBV), and Puumala virus (PUUV). Recently, HTNV-related viruses, Amur (AMR) and Far East (FE) genotypes were identified as causative agents of HFRS in Far Eastern Russia. To investigate the epidemiology of HFRS and virus transmission, we collected sera from 17 acute and 32 convalescent patients who were clinically diagnosed with HFRS in the Khabarovsk region of Far Eastern Russia, and detected anti-hantavirus antibodies using an ELISA that can differentiate the infected virus serotype using truncated hantavirus nucleocapsid protein antigen. Sixteen of the 17 acute phase patients had antibodies to hantavirus, and all the positive sera had higher optical densities for HTNV-specific antigen than for SEOV-, DOBV-, or PUUV-specific antigens. The partial M segment of the viral genome was amplified from blood clots from three acute patients by PCR. The nucleotide sequences had closer identities to the FE genotype (>96%) than to the prototype HTNV (88 to 89%) or AMR genotype (81 to 83%). A phylogenetic analysis found that the virus sequences from the patients clustered with the FE type, and were distinct from the AMR type. Thirty-one of 32 convalescent patient sera had antibodies to HTNV-specific antigen. These data suggest that our ELISA system can detect HTNV-specific antibodies to the FE type, which may be responsible for most of the HFRS in Khabarovsk.

Induction of hepatic DT-diaphorase in mice by butylated hydroxyanisole analogs: a structure-activity study

Butylated hydroxyanisole (BHA) and its analogs were evaluated for their relative activity to induce hepatic DT-diaphorase (EC 1.6.99.2) after dietary administration (at concentrations of 11.1 or 27.7 micromol/g diet for 3 days) to mice. Of the compounds tested, only BHA and 2-tert-amyl-4-methoxyphenol, 4-methoxyphenols with 2-tert-alkyl side chains, were active in inducing DT-diaphorase activity. None of the remaining six compounds showed any significant sign of inducing activity. No simple explanation for these rather strict structural requirements can be offered at the present time.

Small intestinal metastasis from renal cell carcinoma exhibiting rare findings

Small intestinal metastasis from renal cell carcinoma (RCC) has only rarely been described. We report two patients who developed small bowel metastases from RCC showing different clinicopathological characteristics. Both patients underwent hemilateral nephrectomy for RCC and developed lung metastases metachronously or simultaneously. One patient developed occlusive ileus caused by multiple polypoid tumours composed of sarcomatoid tissue in the jejunum shortly after nephrectomy. The other patient presented melaena due to bleeding from a Borrmann 2-like tumour in the jejunum six years after nephrectomy. Clinically, his disease was slow-growing. Sarcomatoid histology and Borrmann 2-like tumour in this report are rare findings in metastatic tumour of RCC in the small bowel.

Characterization of JNK-like protein derived from a mosquito cell line, C6/36

When Western blot analysis of heat-killed bacteria- and lipopolysaccharide (LPS)-treated Aedes albopictus mosquito cell line C6/36 was performed using antiphospholyrated c-Jun amino-terminal kinase (JNK) antibodies, approximately 46 kDa protein was clearly detected with a peak around 30 min. After the C6/36 cells were incubated at 45 degrees C in order to induce apoptosis, the 46 kDa protein continued to be detected for at least 3 h. The internalization of fluorescein-labelled bacteria was inhibited by a JNK-specific inhibitor SP600125, suggesting that phagocytosis involves the JNK signalling pathway in mosquito cells. Based on these results, we found one candidate for the nucleotide sequence of JNK (Ae-JNK) from the C6/36 cells. This study is the first report regarding the mitogen-activated protein kinase (MAPK) of mosquito.

Alterations of quantitative EEG and mini-mental state examination in interferon-alpha-treated hepatitis C

We have recently observed a diffuse slowing of brain waves using serial quantitative electroencephalographic (qEEG) examinations in interferon (IFN)-alpha-treated chronic hepatitis C patients. However, it remains unclear how this alteration could be assessed. We evaluated the correlation between the qEEG changes and three tests of mental status, including the Mini-Mental State Examination (MMSE), in such patients. This is the first study to undertake a clinical evaluation of the adverse effects on brain function due to IFN. We undertook blind, prospective and serial qEEG examinations on 56 chronic hepatitis C patients at three independent hospitals. IFN-alpha was administered intramuscularly at a dose of 9 x 10(6) IU daily for the first 4 weeks and then 3 times/week for the next 20 weeks. Serial EEGs were obtained before, at 2 and 4 weeks of treatment, and after the IFN-alpha treatment. The absolute power values of each frequency band in each patient at different stages of treatment were recorded by qEEG. Each patient was assessed by the MMSE, Hamilton Rating Scale for Depression (HSD), and Hamilton Rating Scale for Anxiety (HSA). We statistically evaluated the correlations between the changes in power values and alterations of scores on the mental status tests during IFN-alpha treatment. The decreased scores observed on the MMSE ranged from 2 to 5 points at both 2 and 4 weeks of IFN-alpha treatment. There were no significant differences in age distribution for each decreased score on the MMSE. As the alteration in MMSE score during IFN treatment increased, the alteration in absolute power values for the slow waves during IFN treatment increased significantly, while that for the alpha 2 and fast waves during treatment decreased significantly. However, the changes in the HDS and HSA revealed no significant correlations. The alteration of the qEEG was reversible after the treatment. MMSE scores represent one screening method for the clinical assessment of IFN-alpha-induced alterations of brain function.

Developmental toxicity of estrogenic chemicals on rodents and other species

Antenatal sex-hormone exposure induces lesions in mouse reproductive organs, which are similar to those in humans exposed in utero to a synthetic estrogen, diethylstilbestrol. The developing organisms including rodents, fish and amphibians are particularly sensitive to exposure to estrogenic chemicals during a critical window. Exposure to estrogens during the critical period induces long-term changes in reproductive as well as non-reproductive organs, including persistent molecular alterations. The antenatal mouse model can be utilized as an indicator of possible long-term consequences of exposure to exogenous estrogenic compounds including possible environmental endocrine disruptors. Many chemicals released into the environment potentially disrupt the endocrine system in wildlife and humans, some of which exhibit estrogenic activity by binding to the estrogen receptors. Estrogen responsive genes, therefore, need to be identified to understand the molecular basis of estrogenic actions. In order to understand molecular mechanisms of estrogenic chemicals on developing organisms, we are identifying estrogen responsive genes using cDNA microarray, quantitative RT-PCR, and differential display methods, and genes related to the estrogen-independent vaginal changes in mice induced by estrogens during the critical window. In this review, discussion of our own findings related to endocrine distuptor issue will be provided.

Antenatal diagnosis and treatment of a case of fetal goitrous hypothyroidism associated with high-output cardiac failure

A case of fetal goitrous hypothyroidism associated with high-output cardiac failure is presented. At 32 weeks of gestation, the antenatal diagnosis of goiter was made based on ultrasound examination, and the fetal thyroid function was examined by amniocentesis and cordocentesis. Color and pulsed Doppler examinations demonstrated a high vascular flow pattern in the goiter and marked elevation of the maximum velocity in the common carotid artery at the level of the neck. It was suspected that arteriovenous shunting through the large goiter resulted in high-output cardiac failure with cardiomegaly and pleural effusion. The fetus was treated by injection of levothyroxine sodium into the amniotic fluid at 33 weeks of gestation and the goiter thereafter decreased in size, with subsequent improvement of the high-output cardiac failure. The maximum velocity in the common carotid artery fell rapidly before the shrinkage of the fetal goiter and in parallel with the fetal level of thyroid stimulating hormone.

Genome-wide analysis of changes in early gene expression induced by oestrogen

BACKGROUND

The sex hormone 17beta-oestradiol (E2) has profound effects on many aspects of reproduction, development, as well as behaviour. Although the oestrogen receptor is well characterized on a molecular level, relatively few genes affected by E2 have been identified, and the mechanisms underlying the physiological changes caused by E2 are largely unknown. In order to identify oestrogen-regulated genes in vivo, early uterine gene expression profiles were developed using DNA microarrays.

RESULTS

Ovariectomized mice were exposed to 17beta-oestradiol for 6 h, and mRNA expression analysis for 9977 genes was performed. Although a large number of genes was affected by oestrogen administration, the genes that showed higher reproducibility in repetitive experiments were selected and further examined. For most of the selected genes, expression was induced in a dose-dependent manner, and gene expression was not altered following oestrogen treatment in oestrogen receptor-alpha (ER(alpha))-deficient mice. In combination with the estimation of gene expression levels using quantitative PCR, it was revealed that multiple genes related to sterol biosynthesis, tRNA synthesis, RNA processing, and growth signalling were activated. Based on the microarray data, we selected additional genes related to sterol biosynthesis and tRNA synthesis and confirmed that these genes are also activated by oestrogen.

CONCLUSION

Genes suggesting a basis for the drastic uterotrophic effect observed several days following oestrogen administration were identified. These findings not only reveal the diverse effect of oestrogen signalling on transcript levels in vivo but also demonstrate the ability of DNA microarrays to identify cellular pathways affected by oestrogen.

Beneficial effect of JTV-803, a new synthetic inhibitor of activated factor X, against both lipopolysaccharide-induced and tissue factor-induced disseminated intravascular coagulation in rat models

We examined whether JTV-803, a specific activated factor X inhibitor independent of antithrombin III (ATIII), is effective against disseminated intravascular coagulation (DIC) in rat models induced by tissue factor (TF) or lipopolysaccharides (LPS). In male Wistar rats, DIC was induced by a 4 h infusion of thromboplastin (3.75 U/kg) or LPS (50 mg/kg). The rats were given JTV-803 (0.3 or 3 mg/kg, bolus intravenously) (JTV-803 groups) or low molecular weight heparin (LMWH groups) (200 U/kg, bolus intravenously) prior to an injection of TF or LPS. The results showed that JTV-803 was dose-dependently effective against DIC in both TF-induced and LPS-induced rat models. This anti-DIC effect of JTV-803 at higher doses was almost equivalent to that of LMWH in both types of DIC. Plasma ATIII activity was more prominent in the group treated with JTV-803 than in that treated with LMWH. None of rats died in the TF-induced DIC model with or without drug administration. On the contrary, seven of 22 rats died (mortality rate, 31.8%) in the LPS-induced DIC model without drug administration. Although the mortality rate of rats induced with LPS and treated with LMWH was quite high (6/16, 37.5%), none of the LPS-induced rats treated with JTV-803 died. These findings suggested that JTV-803 can treat both TF-induced and LPS-induced DIC models, and that this drug has greater potential in preserving ATIII and in improving the prognosis of DIC.

[Neuro-infections to be borne in mind]

We presented atypical manifestations in tuberculous meningitis (TbM) and herpes simplex encephalitis (HSE), lymphocytic dominant cerebrospinal fluid pleocytosis in bacterial meningitis, and a hitherto easily overlooked critical illness polyneuropathy (CIP) associated with sepsis. 1) We presented 2 TbM patients with atypical manifestations. One patient was a 25-year-old man who exhibited polymorphonuclear (PMN) dominant pleocytosis in CSF throughout his clinical course. He died the next day after a CSF culture yielded the growth of tuberculous bacilli, before receiving appropriate anti-TBM therapy. This was a rare TbM example of persistent PMN dominant CSF pleocytosis. The other patient was a 39-year-old woman whose CSF pleocytosis changed from lymphocytic dominant to PMN dominant about 1 month after the initiation of antituberculous chemotherapy. This CSF change was followed by multiple cerebral infarcts due to vauculitis caused by TbM. Administration of prednisolone caused marked improvement of the patient's symptomatology. Tuberculomas appeared transiently during anti-TbM therapy, consistent with paradoxical progression of tuberculoma. 2) A few patients with HSE may show atypical CSF findings such as PMN dominant pleocytosis, absence of pleocytosis, and low sugar value. Our national survey of HSE patients showed following percentages of these atypical findings: PMN dominant pleocytosis observed in 10% of the patients in the early stage and at the time of exacerbation, no pleocytosis in 0.9% (1 patient), and low sugar value in 4%. 3) Bacterial meningitis typically causes PMN dominant CSF pleocytosis. However, Listeria meningitis (LM) may cause lymphocytic dominant pleocytosis in 30% of the patients, particularly in elderly ones. We showed one such 69-year-old patient with persistent lymphocytic dominant CSF pleocytosis throughout the clinical course. 4) CIP, septic encephalopathy and critical illness myopathy are 3 major complications associated with sepsis. CIP is a frequent cause of neuromuscular weakness due to axonal dysfunction, which occurs to critically ill patients with sepsis, particularly when multiple organ dysfunctions are present. We showed our CIP patient associated with acute bacterial endocarditis and multiple organ failure. We should bear in mind these atypical manifestations, and frequent and important complications associated with sepsis such as CIP, to provide appropriate management to patients with neuro-infection and sepsis.

Vitamin K administration to elderly patients with osteoporosis induces no hemostatic activation, even in those with suspected vitamin K deficiency

The administration of menaquinone-4 (MK-4), one of subclasses of vitamin K2, significantly reduces bone loss in postmenopausal osteoporotic women. However, concerns have been raised about whether vitamin K administration alters the hemostatic balance by inducing a thrombotic tendency. We investigated were whether the administration of vitamin K in the form of MK-4 induced a thrombotic tendency in 29 elderly patients with osteoporosis (5 men, 24 women; age range 78.7+/-5.1 years). Patients were administered 45 mg/day (three times a day, 30 min after each meal) of MK-4 for 12 weeks. Blood samples were obtained from the patients at 0, 4 and 12 weeks after the start of MK-4 administration. A number of hemostatic parameters remained stable under the markedly increased plasma levels of MK-4. However, in patients with suspected vitamin K deficiency, whose plasma levels of vitamin K or factor VII were low, vitamin-K-dependent clotting factors such as factor VII and prothrombin were gradually increased after administration of MK-4. No changes in the sensitive molecular markers such as TAT and F1+2, which reflect the amount of thrombin generated in the blood stream, were observed, even in those patients with suspected vitamin K deficiency. These results indicate that MK-4 can be administered safely, with regard to maintaining the hemostatic balance, to osteoporotic patients receiving no anticoagulant therapy.

[A case with left mesial temporal lobe epilepsy characterized by abnormal massive salivation]

A 26-year-old woman was admitted because of a 12-year history of intractable epileptic seizures. Every seizure began with an upper abdominal discomfort, and often followed by massive salivation. Whenever the epileptic salivation happened, the patient lost consciousness, and sometimes she developed generalized convulsions. In terictal sphenoidal EEG recordings revealed abnormal discharges in the left mesial temporal region. MRI demonstrated left hippocampal atrophy. Since her seizures were medically intractable, left temporal lobectomy was performed. Neuropathologic examination revealed hippocampal sclerosis. After the operation, she became completely seizure-free with no episode of massive salivation. From the literature, epileptic salivation can originates from the rolandic area; fronto-orbital cortex & cingulate gyrus; insula & operculum; and mesial temporal structures. The abnormal massive salivation in our patient might be attributable to the activation of frontal limbic system triggered by hippocampal abnormal firing during the ictal period of TLE.

FR226807: a potent and selective phosphodiesterase type 5 inhibitor

We describe the pharmacological characteristics of a novel phosphodiesterase type 5 inhibitor FR226807, N-(3,4-dimethoxybenzyl)-2-[[(1R)-2-hydroxy-1-methylethyl]amino]-5-nitrobenzamide. FR226807 inhibited phosphodiesterase type 5 isolated from human platelets with an IC(50) value of 1.1 nM. FR226807 also inhibited phosphodiesterase type 6 with an IC(50) of 20 nM; however, the IC(50) value for phosphodiesterase type 6 was 18-fold higher than that for phosphodiesterase type 5. The IC(50) values of FR226807 for other phosphodiesterases (phosphodiesterase type 1, phosphodiesterase type 2, phosphodiesterase type 3, and phosphodiesterase type 4) were 1000-fold higher than that for phosphodiesterase type 5. FR226807 increased the cyclic guanosine monophosphate (cGMP) content in corpus cavernosum isolated from rabbit, an effect associated with relaxation of the muscle. FR226807 enhanced the relaxation response induced by electrical field stimulation of corpus cavernosum isolated from the rabbit. In an anesthetized dog model for the evaluation of erectile function, intravenous administration of FR226807 prolonged the time to return to 75% of maximal intracavernosal pressure after cessation of electrical stimulation of the pelvic nerve. In summary, FR226807 is a potent and highly selective phosphodiesterase type 5 inhibitor with an augmentative effect on penile erection and will be useful for the treatment of erectile dysfunction.