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Biomedical subjects

M Baba

Publications and source records attributed to M Baba.

At least 91 records · Page 5Linked to original sources
PubMed1991

Enhancement by sulpiride of the inhibitory effects of cysteamine on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The effects of sulpiride on cysteamine inhibition of gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and on the BUdR labelling index of gastric mucosa were investigated in inbred Wistar rats. After 25 weeks of oral treatment with MNNG, rats received one of the following alternate-day injections: cysteamine (2 doses), cysteamine (2 doses) plus sulpiride or sulpiride. At week 52, prolonged administration of cysteamine significantly reduced the incidence of adenocarcinomas of the glandular stomach. Cysteamine at low dose had no effect on the incidence of gastric cancers, but a combination of low-dose cysteamine and sulpiride caused a significantly greater reduction in the incidence of gastric cancers. Administration of sulpiride alone had no influence on gastric carcinogenesis. The labelling index of the antral mucosa was significantly lower in rats treated with high but not low doses of cysteamine. However, a combination of low-dose cysteamine and sulpiride significantly decreased the labelling index of the antral mucosa. Our findings indicate that cysteamine suppressed gastric carcinogenesis and that sulpiride enhanced this inhibition. Because sulpiride is a dopamine antagonist, these findings also indicate that dopamine may play an important role in cysteamine inhibition of gastric carcinogenesis.

Animals↗
PubMed1991

An application of tetrazolium (MTT) colorimetric assay for the screening of anti-herpes simplex virus compounds.

A rapid and sensitive procedure was developed for in vitro evaluation of anti-herpes simplex virus (HSV) agents. The procedure is based on spectrophotometrical assessment for viability of virus- and mock-infected cells via in situ reduction of a tetrazolium dye MTT, which has already been used for the detection of anti-human immunodeficiency virus (HIV) agents (Pauwels et al., 1988). Monolayer cells such as human embryonic fibroblast, VERO, or HeLa cells were not suitable for this purpose. Among the non-adherent cell lines examined for susceptibility to HSV type 1 (HSV-1), a B-lymphoblastoid cell line NC-37 was found to be the most sensitive. The cell line was found to have a good correlation between the viable cell number and the reduction of MTT. In addition, centrifugation of the virus-infected cells resulted in further increase of the sensitivity of NC-37 cells to HSV-1. After optimization, the method proved to be as sensitive as plaque reduction. The system simplifies significantly the assay procedures and thus permits the evaluation of larger numbers of compounds for anti-HSV-1 activity.

Animals↗
PubMed1991

Synergistic inhibition of human immunodeficiency virus type 1 (HIV-1) replication in vitro by 1-[(2-hydroxyethoxy)methyl]-6-phenylthiothymine (HEPT) and recombinant alpha interferon.

1-[(2-Hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) has recently proved to be a potent and selective inhibitor of human immunodeficiency virus type 1 (HIV-1) in vitro. Combinations of HEPT and recombinant alpha interferon (IFN-alpha) synergistically inhibit the replication of HIV-1 in MT-4 cells at non-toxic concentrations. Synergistic inhibition of HIV-1 replication has also been observed in peripheral blood lymphocytes. These results indicate that the combination of HEPT with IFN-alpha should be further pursued in the treatment of retrovirus infections [i.e. acquired immune deficiency syndrome (AIDS)].

Acquired Immunodeficiency Syndrome↗
PubMed1991

Potential anti-AIDS agents. Synthesis and antiviral activity of naphthalenesulfonic acid derivatives against HIV-1 and HIV-2.

Certain naphthalenesulfonic acid analogues have been synthesized and evaluated for their inhibitory effects on HIV-1- and HIV-2-induced cytopathogenicity, HIV-1 giant cell formation, and HIV-1 reverse transcriptase (RT) activity. A bis(naphthalenedisulfonic acid) derivative having a biphenyl spacer emerged as the most potent and selective inhibitor of virus-induced cytopathogenicity in MT-4 cells. The ED50 values for this compound were 7.6 and 36 microM for HIV-1 and HIV-2, respectively. No toxicity to the host cells was detected at 98 microM. This compound also inhibited giant cell formation and was superseded in potency by a bis(naphthalenedisulfonic acid) derivative having a flexible decamethylene spacer. In the cell-free RT assay, a long-chain amide derivative exhibited the most inhibition of RT. All the compounds that achieved complete inhibition of virus-induced cytopathogenicity at concentrations not toxic to host cells were derivatives of 4-amino-5-hydroxy-2,7- naphthalenedisulfonic acid. These analogues represent new leads for the development of anti-HIV agents.

Acquired Immunodeficiency Syndrome↗
PubMed1991

A new class of HIV-1-specific 6-substituted acyclouridine derivatives: synthesis and anti-HIV-1 activity of 5- or 6-substituted analogues of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT).

A series of novel acyclouridine derivatives substituted at both the C-5 and C-6 positions were synthesized for the purpose of improving the activity of a recently reported HIV-1-specific lead, 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT). Preparation of C-6 substituted derivatives was carried out based on the following three methods: (1) LDA (lithium diisopropylamide) lithiation of a thymine derivative (4) and subsequent reaction with electrophiles, (2) an addition-elimination reaction of HEPT or its 6-(phenylsulfinyl) derivative (10), or (3) palladium-catalyzed cross-coupling between a 6-iodo derivative (16) and terminal alkynes. Following the methods, 21 C-6 substituted analogues were synthesized. Among these, 6-(cyclohexylthio) (8), 6-phenoxy (13), and 6-benzyl (27) derivatives showed anti-HIV-1 (HTLV-IIIB) activity with EC50 values of 8.2, 85, and 23 microM, respectively. Preparation of C-5 substituted derivatives was based on either LTMP (lithium 2,2,6,6-tetramethylpiperidide) lithiation of 6-(phenylthio)uracil derivative 37 or the above mentioned palladium-catalyzed cross-coupling of a 5-iodo-6-(phenylthio)uracil derivative (38). Following these methods, 11 C-5 substituted analogues were synthesized. Some 5-substituted derivatives (5-I, 44; 5-CH = CPh2, 49; 5-CH = CHPh (Z), 54; and 5-CH = CH2, 55) were more active than HEPT, but their selectivity indices (SI = CC50/EC50) were lower than that of HEPT. Compound 8 was also evaluated against another HIV-1 strain (HTLV-IIIRF) and HIV-2 strains (LAV-2ROD and LAV-2EHO). Only HTLV-IIIRF was as sensitive as HTLV-IIIB.

Antiviral Agents↗
PubMed1991

Synthesis and anti-HIV activity of 2-, 3-, and 4-substituted analogues of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT).

Several analogues of a new lead for anti-HIV-1 agents, 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT), in which the C-2, N-3, or C-4 position was modified were synthesized. These involve 2-thiothymine (11), 2-thiouracil (12), 4-thiothymine (17), 4-thiouracil (18), 5-methylcytosine (27), and cytosine (28) derivatives. Preparation of N-3-substituted derivatives (29 and 30) of HEPT was also carried out. Among these analogues, compound 11 exhibited excellent activity against HIV-1 HTLV-IIIB strain with an EC50 value of 0.98 microM, which is 7-fold more potent than that of HEPT. Removal of the 5-methyl group in compound 11 results in total loss of activity. Other compounds did not show any anti-HIV-1 activity. The 4-thio derivatives 17 and 18 were found to be rather cytotoxic. When compound 11 was evaluated for its inhibitory effects on another HIV-1 strain, HTLV-IIIRE, and two HIV-2 strains, LAV-2ROD and LAV-2EHO, it proved equally inhibitory to HTLV-IIIRF, whereas both HIV-2 strains were insensitive to the compound.

Antiviral Agents↗
PubMed1991

Comparative inhibitory effects of nucleoside analogues on different clinical isolates of human cytomegalovirus in vitro.

Various nucleoside analogues were examined for their inhibitory effects on plaque formation of the laboratory strain AD-169 and 11 clinical isolates of human cytomegalovirus (CMV) in human embryonic fibroblast (MRC-5) cells. The most selective inhibitors of CMV replication were 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG), (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC), and (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine (HPMPA). The 50% effective concentrations (EC50) for CMV plaque formation were 0.65, 0.25, and 0.28 microgram/ml, respectively. Selectivity indexes were 462, 300, and 107, respectively. At a concentration fourfold higher than the EC50, HPMPC completely inhibited CMV growth, whereas DHPG still allowed it. Carbocyclic 3-deazaadenosine, recognized as an S-adenosylhomocysteine (SAH) hydrolase inhibitor, had an EC50 of 13.7 micrograms/ml and a selectivity index of 29. These results suggest that HPMPC should be further pursued for its usefulness in the treatment of CMV infections and SAH hydrolase inhibitors represent potentially important anti-CMV agents.

Adenine↗
PubMed1991

Larval instars and growth pattern of a univoltine black fly, Prosimulium kiotoense (Diptera: Simuliidae), in Kyushu, Japan.

Seven larval instars were detected for a natural population of Prosimulium kiotoense Shiraki in Kyushu, Japan, from the size frequency distribution of postgenal lengths. Growth in P. kiotoense larvae followed a geometric progression from first to sixth instars, but the size ratio between sixth and seventh instars was smaller than between other successive stadia. The linear relationship between the mean instar value and daily cumulative water temperature indicated that development between instars required 82.6 degree-days (DD). The accumulated temperature for larval development of this species was estimated to be 600 DD.

Animals↗
PubMed1991

Protective effect by potassium chloride against gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in spontaneously hypertensive rats.

The effects of oral potassium supplementation on the enhanced induction of gastric carcinogenesis by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in spontaneously hypertensive rats (SHR), and the norepinephrine concentration in their gastric wall were investigated. The SHR and normotensive Wistar Kyoto rats (WKY) as controls were given a solution of the carcinogen for 25 weeks and then 1% KCl solution or tap water to drink. In Week 52, the incidence of gastric cancers and their number per rat and the norepinephrine concentration in the gastric wall were significantly greater in SHR than in WKY. Prolonged oral treatment of SHR with potassium significantly reduced the incidence of gastric cancers and their number per rat, as well as the blood pressure and the norepinephrine concentration in the antral portion of the gastric wall. These findings indicate that prolonged treatment with KCl attenuated the enhancement of gastric carcinogenesis by MNNG in SHR.

Animals↗
PubMed1991

Inhibition by xiao-chai-hu-tang (TJ-9) of development of hepatic foci induced by N-nitrosomorpholine in Sprague-Dawley rats.

The effect of Xiao-chai-hu-tang (TJ-9) on hepatocarcinogenesis induced by N-nitrosomorpholine (NNM) was investigated in male Sprague-Dawley rats. Rats were given normal chow pellets containing 0.5% or 1.0% TJ-9 until the end of the experiment, and drinking water containing NNM for 8 weeks. Pre-neoplastic and neoplastic lesions staining for gamma-glutamyl transpeptidase (GGT) or the placental type of glutathione-S-transferase (GST-P) were examined histochemically. In Week 15, quantitative histological analysis showed that prolonged treatment with 0.5% TJ-9 significantly reduced the number and volume of GGT-positive and GST-P-positive hepatic lesions. Treatment with 1.0% TJ-9 inhibited the development of GGT-positive and GST-P-positive lesions, but was less effective than 0.5% TJ-9. Administration of 0.5% TJ-9 also caused a significant increase in the proportion of helper T lymphocytes and a significant decrease in the labeling index of pre-neoplastic lesions. These findings indicate that TJ-9 inhibits the development of hepatic foci.

Animals↗
PubMed1991

Oviposition habits of a univoltine blackfly, Prosimulium kiotoense (Diptera: Simuliidae), in Kyushu, Japan.

Oviposition habits of a univoltine mammalophilic blackfly, Prosimulium kiotoense Shiraki, were investigated at a stream in Kyushu Island, Japan. The flies oviposited on bryophyte mosses growing on river bank rock surfaces. The eggs were laid singly, but large irregular egg masses were often formed because many females oviposited within the same small areas. Wet sites with dense bryophyte cover at heights between 0 and 15 cm above water level were selected for oviposition. Oviposition activity was observed in the latter half of April. P. kioteonse females came to the site to lay eggs after 11.00 hours in the morning, when air temperature rose to about 15 degrees C. Peak ovipositional activity occurred between 12.00 and 14.00 hours.

Animals↗
PubMed1991

Synergistic inhibition of human immunodeficiency virus type 1 replication by 5-ethyl-1-ethoxymethyl-6-(phenylthio)uracil (E-EPU) and azidothymidine in vitro.

A novel 6-substituted acyclouridine derivative, 5-ethyl-1-ethoxymethyl-6-(phenylthio)uracil (E-EPU), has recently proved to be a highly potent and selective inhibitor of human immunodeficiency virus type 1 (HIV-1) in vitro. Combinations of 3'-azido-2',3'-dideoxythymidine (AZT) and E-EPU synergistically inhibit the replication of HIV-1 in MT-4 cells, whereas the cytotoxic effects of AZT and E-EPU on mock-infected MT-4 cells are not enhanced by the drug combination. Synergistic inhibition of HIV-1 replication has also been observed in peripheral blood lymphocytes. These results indicate that the combination of AZT and E-EPU should be further pursued in the treatment of AIDS.

Antiviral Agents↗
PubMed1991

Antiviral activities of glycyrrhizin and its modified compounds against human immunodeficiency virus type 1 (HIV-1) and herpes simplex virus type 1 (HSV-1) in vitro.

Chemically modified compounds of glycyrrhizin have been synthesized and evaluated for their inhibitory effect on the replication of human immunodeficiency virus type 1 (HIV-1) and herpes simplex virus type 1 (HSV-1). Among them, the 11-deoxo compound having a heteroannular diene structure at the C and D rings proved as active against HIV-1 as glycyrrhizin in MT-4 and MOLT-4 cells. It completely inhibited HIV-1-induced cytopathogenicity in both cell lines at a concentration of 0.16 mM. The compound was also effective against HSV-1 with a 50% inhibitory concentration of 0.5 mM [corrected].

Antiviral Agents↗
PubMed1991

[A case of spontaneous regression of lung cancer with skin metastasis].

Spontaneous regression of a malignant tumor is a rare phenomenon, especially in advanced lung cancer. We reported a case of spontaneous regression of lung cancer with tracheal stenosis due to tumor invasion and multiple skin metastases. A 60-year-old man was admitted to our hospital on September 10, 1985, because of a dry cough. A chest roentgenogram showed a mass shadow in the right upper lung field. Bronchoscopic examination revealed tracheal stenosis due to the tumor mass, and transbronchial aspiration cytology (TBAC) yielded a diagnosis of large cell carcinoma of the lung. In spite of treatment by chemotherapy with cisplatin and vindesin and irradiation, dyspnea deteriorated and multiple skin metastases appeared. After Nd-YAG laser irradiation via a broncho-fiberscope to maintain his airway and ethanol injection into the skin metastases, his dyspnea improved and he was discharged on February 6, 1986. Two months after discharge all skin metastasis had completely disappeared, and the primary lesion also regressed and finally disappeared on chest roentgenogram until August, 1986. The mechanism of regression is unclear, but now he has been free of tumor clinically for four years.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

In vivo and in vitro invasiveness of human lung carcinoma cell lines.

Eight cell lines derived from human non-small cell lung carcinomas were used to compare their in vivo invasiveness, in vitro chemoinvasive abilities and type IV collagenase activity. For the evaluation of the in vivo invasive potential, the tumor cells were seeded into deepithelialized rat tracheas and transplanted subcutaneously into nude mice. The invasive behavior of the cells was observed at 4, 8 and 12 weeks and assessed histologically by determination of the levels of penetration of tumor cells into the different layers of the tracheal wall. Except for two cell lines that did not grow at all in vivo, there was a very good correspondence between the levels of in vivo tracheal wall penetration and the in vitro chemoinvasion assay using fibronectin as chemoattractant and Matrigel as barrier. This also correlated very well with the capacity of the cells to secrete type IV collagenase. The in vivo evaluation of invasion using tracheal transplants, although requiring several weeks of experimentation, proved to be very reliable, yielding homogeneous results with little internal variation, and is proposed as a dependable in vivo invasion assay that closely mimics the in vivo human conditions in which most carcinomas develop and eventually invade neighboring tissues.

Animals↗
PubMed1991

Superficial esophageal carcinoma: a clinicopathological review of 59 cases.

During the period from 1975 to 1989, a total of 59 patients with superficial esophageal carcinoma (SEC) were operated on in our Surgical Clinic. Forty patients of the 59 (68%) had been treated during the previous 5 yr. Although 22 patients (37%) complained of slight esophageal symptoms, 12 patients had only symptoms unrelated to esophageal disease, and 25 patients were asymptomatic. In the latter patients, the lesion was found by chance at the time of screening or follow-up examination of upper gastrointestinal tract disease. Endoscopy was very useful for the diagnosis of SEC, and Lugol's solution staining technique was an effective adjunctive means. The lesions in about half of the patients were initially diagnosed by endoscopy in our series. Radiologic diagnosis of the lesions confined to the mucosal epithelium or lamina propria was particularly difficult. Lymph node metastasis was not observed in patients with intraepithelial or mucosal carcinoma. However, the metastasis was demonstrated in 18 of 38 patients (47%) with submucosal invasion. The 5-yr survival rate of patients with SEC was 73%, which was significantly superior to that of patients with advanced esophageal carcinoma (26%). Since the prognosis for the patients with submucosal invasion and lymph node metastasis was poor, we should be enthusiastic about extended lymph node dissection in the surgical treatment for patients in whom submucosal invasion is suspected.

Adenocarcinoma↗