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Biomedical subjects

Y Natsume

Publications and source records attributed to Y Natsume.

12 recordsLinked to original sources
PubMed1999

Thin cement mantle and osteolysis with a precoated stem.

The radiographic and clinical results of 55 hips (52 patients) implanted with the Harris precoat hip prosthesis using second generation cementing technique were investigated in this study. All metal backed sockets were fixed with cement. The preoperative diagnoses were osteoarthritis secondary to dysplastic hips in 42 patients, primary osteoarthritis in six, rapidly destructive coxarthrosis in five, and osteonecrosis of the femoral head in two. The average age of patients at the time of surgery was 67 years. The average duration of followup was 8 years. The rates of aseptic loosening and osteolysis in the femoral side were 5.5% (three hips) and 12.7% (seven hips), respectively. Three sockets were loosened, and no osteolysis was detected in the acetabular side. The mantle of cement in the femur was graded using the criteria described by Mulroy et al. Twenty-seven of 55 (49%) hips had regions with a thin cement mantle less than 1 mm in thickness or a defect in the cement mantle. Osteolysis was detected in seven of the 27 (26%) hips. Locations of osteolysis were coincidental with those of thin cement mantle or defect with the exception of one hip. This study clearly shows that a thin cement mantle less than 1 mm in thickness and a defect in the cement mantle lead to osteolysis.

Acetabulum↗
PubMed1998

Differing patterns of P-selectin expression in lung injury.

Using two models of acute lung inflammatory injury in rats (intrapulmonary deposition of immunoglobulin G immune complexes and systemic activation of complement after infusion of purified cobra venom factor), we have analyzed the requirements and patterns for upregulation of lung vascular P-selectin. In the immune complex model, upregulation of P-selectin was defined by Northern and Western blot analysis of lung homogenates, by immunostaining of lung tissue, and by vascular fixation of 125I-labeled anti-P-selectin. P-selectin protein was detected by 1 hour (long before detection of mRNA) and expression was sustained for the next 7 hours, in striking contrast to the pattern of P-selectin expression in the cobra venom factor model, in which upregulation was very transient (within the 1st hour). In the immune complex model, injury and neutrophil accumulation were P-selectin dependent. Upregulation of P-selectin was dependent on an intact complement system, and the presence of blood neutrophils was susceptible to the antioxidant dimethyl sulfoxide and required C5a but not tumor necrosis factor alpha. In contrast, in the cobra venom factor model, upregulation of P-selectin, which is C5a dependent, was also dimethyl sulfoxide sensitive but neutrophil independent. Different mechanisms that may explain why upregulation of lung vascular P-selectin is either transient or sustained are discussed.

Animals↗
PubMed1996

Effect of SM-12502 on disseminated intravascular coagulation (DIC) in tumor-bearing rats.

To investigate the role of PAF in tumor-associated disseminated intravascular coagulation (DIC), we have established the tumor-induced DIC model in rats and examined the effect of PAF-antagonist as compared with commonly used anti-DIC drugs. Four days after the intraperitoneal inoculation of rat ascites hepatoma AH-130, DIC-like hematological parameter changes such as decrease in platelet count, prolongation of PTT and increase in FDP were observed. In addition, serum levels of GOT and GPT were increased, indicating that liver injury was provoked. PAF-antagonist SM-12502 inhibited the development of DIC (PT, PTT and FDP) and liver injury. These results indicate that PAF plays an important role in tumor-associated DIC as well as accompanying organ failure.

Alanine Transaminase↗
PubMed1994

Effects of platelet activating factor receptor antagonists on intracellular platelet activating factor function in neutrophils.

We investigated the effects of the platelet activating factor (PAF) receptor antagonists, SM-12502 ((+)-cis-3,5-dimethyl-2-(pyridyl)- thiazolidin-4-one hydrochloride), WEB-2086 (3-(4-(2-chlorphenyl)-9-methyl-6H-thieno(3,2-f)-(1,2,4)triazolo(4, 3- a)(1,4)diazepin-2-yl)-1-(4-morpholinyl)-1-propanone) and RP-48740 (3-(3-pyridyl)-1H,3H-pyrrolo[1,2-c]thiazole-7-carboxamide) on the PAF-mediated activation of rat neutrophils. These antagonists inhibited PAF-induced degranulation and chemotaxis in neutrophils at a dose that correlated well with PAF-induced platelet aggregation based on the statistical analyses. N-formyl-L-methionyl-L-leucyl-L- phenylalanin (fMLP)-induced cellular responses were also inhibited by the PAF receptor antagonists, but their inhibitory potencies did not correlate with those for PAF-induced platelet aggregation. In addition, the doses required for inhibition were higher than those required against PAF-induced responses (i.e. IC50 ratio of WEB-2086, SM-12502 and RP-48740 in fMLP-induced/PAF-induced degranulation was 40.0, 2.8 and 5.6, respectively). PAF receptor antagonists inhibited inositol 1,4,5-triphosphate production and the release of Ca2+ from the intracellular store site after stimulation with PAF. In the fMLP-induced responses, PAF receptor antagonists did not inhibit IP3 production and Ca2+ release, but did inhibit transmembrane Ca2+ influx. These results suggest the presence of distinct PAF receptor subtype, to which exogenously added PAF binds, while endogenously produced PAF binds to the other. Intracellular PAF, which was produced by fMLP-stimulation, may play an important role in the late phase of signal transduction, and may participate in the transmembrane Ca2+ influx.

Animals↗
PubMed1994

Effect of the platelet activating factor antagonist (+)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one hydrochloride on endotoxin-induced hypotension and hematological parameters in rats.

The intravenous administration of endotoxin to anesthetized rats resulted in different hypotensive reactions depending on its dosage. More than 10 mg/kg of endotoxin induced biphasic hypotension; the first phase consisted in a small and transient depression (approximately 15 mmHg) of mean arterial pressure occurred within 1 min after the administration, and the second phase was a large and sustained depression (maximally 40 mmHg) observed from 1 h after the injection. At less than 3 mg/kg of endotoxin, the first phase of hypotension did not occur whereas the second phase of hypotension was observed. Pre-treatment or post-treatment with a specific platelet activating factor (PAF) antagonist, SM-12502 ((+)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one HCl, CAS 119383-00-5) inhibited the second phase of endotoxin (1 mg/kg)-induced hypotension. In addition, post-treatment with another PAF antagonist, (3-(4-(2-chlorophenyl)-9-methyl-6H-thieno (3,2-f) (1, 2,4)-thiazolo-phenone) also inhibited the second phase of hypotension. Blood PAF-like substance level, measured by the PAF radioimmunoassay, slightly increased at 1 min after administration of endotoxin (30 mg/kg). At 90 min after the injection, endotoxin (1 mg/kg) induced a significant increase of PAF-like substance level.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Biological effects of the new platelet-activating factor receptor antagonist (+)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one hydrochloride.

SM-12502 ((+)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one HCl, CAS 119383-00-5) inhibited platelet-activating factor (PAF)-induced aggregation of rabbit and human platelets with IC50 values of 2.3 mumol/l and 4.7 mumol/l, respectively, but did not inhibit platelet aggregation induced by adenosine diphosphate, collagen, thrombin, arachidonic acid, U46619 (a thromboxane A2 agonist) or Ca2+ ionophore A23187 at concentrations up to 400 mumol/l. SM-12502 competitively antagonized 3H-PAF binding to rabbit platelets with an IC50 of 1.0 mumol/l. In contrast, the anti-PAF activity of the optical isomer SM-12501 ((-)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one HCl) was much weaker and its IC50 was more than 100 mumol/l. SM-12502 prevented PAF-induced death in mice with ID50 values of 4.8 mg/kg (i.v.) or 68.6 mg/kg (p.o.). In guinea pigs, SM-12502 inhibited PAF (0.1 micrograms/kg)-induced hemoconcentration with ID50 values of 1.9 mg/kg (i.v.) or 40.2 mg/kg (p.o.). In addition, SM-12502 inhibited PAF (10 ng/kg)-induced hypotension in rats with ID50 values of 2.0 mg/kg (i.v.) or 6.5 mg/kg (p.o.). The in vivo effects of SM-12501 were much weaker. Orally administered SM-12502 showed rapid absorption and a long duration of pharmacological activity in rats. SM-12502 afforded dose-dependent protection against anaphylactic death in mice with ID50 values of 18.4 mg/kg (i.v.) and 136 mg/kg (p.o.). It also inhibited endotoxin (E. coli 0.55:B5, 60 mg/kg)-induced death in mice, with ID50 values of 119 mg/kg (i.v.) and 182 mg/kg (p.o.).(ABSTRACT TRUNCATED AT 250 WORDS)

Anaphylaxis↗
PubMed1991

Gastric hyperacidity and mucosal damage caused by hypothermia correlate with increase in GABA concentrations of the rat brain.

The involvement of brain GABA mechanisms in acid secretion and maintenance of gastric mucosal integrity was studied in the anesthetized rat. Cold exposure lowered the rectal temperature and stimulated acid output in the anesthetized rat. The acid response to cold exposure was completely suppressed by surgical vagotomy. The substantial increase in brain GABA content evoked by pretreatment with aminooxyacetic acid (10 and 20 mg/kg s.c. x 3) significantly potentiated the gastric acid response to the cold exposure stress; suppression of the GABA content induced by semicarbazide (100 mg/kg s.c.) reduced the acid response to cold. Significant correlations were found between the brain GABA contents and the acid secretory activity and also between the GABA contents and the ulcer index of gastric lesions induced by the cold stress. These results indicate that hypothermia evoked by cold exposure stimulates gastric acid secretion and induces gastric lesions through central GABA mechanisms in the rat.

Aminooxyacetic Acid↗
PubMed1990

Gastric acid inhibitory action of a GABA-related compound, 3-amino-3-phenylpropionic acid, in the rat.

The acid inhibitory properties of 3-amino-3-phenylpropionic acid, a structural GABA analogue, were studied in the perfused rat stomach preparation. 3-Amino-3-phenylpropionic acid, 10 and 30 mg/kg i.v., dose dependently suppressed the gastric acid secretion induced by baclofen (2 mg/kg s.c.). This secretagogue action had been shown to be unaffected by either GABAA or GABAB receptor antagonists. The i.v. administration of 3-amino-3-phenylpropionic acid (3 and 10 mg/kg) was also effective to abolish the acid stimulatory effects of muscimol (1 mg/kg i.v.) and 2-deoxy-D-glucose (200 mg/kg i.v.). 3-Amino-3-phenylpropionic acid, even at the high dose (30 mg/kg i.v.) had no influence on the acid output in response to histamine and bethanechol. Furthermore, 3-amino-3-phenylpropionic acid had no significant effect on the acid secretion induced by electrical vagal stimulation. These results indicate that the antisecretory effect of 3-amino-3-phenylpropionic acid is different from those of antimuscarinics, H2-receptor antagonists and vagal blockade. Together, the results suggest that 3-amino-3-phenylpropionic acid might act in the brain to inhibit central regulation mechanisms of gastric acid secretion, probably through GABA mechanisms.

Animals↗
PubMed1990

[Ulcerogenic effect of a GABA derivative, baclofen, in the rat: effect of hypothermia].

The ulcerogenic action of baclofen, a lipophilic derivative of GABA, was studied in the urethane anesthetized rat in relation to body temperature. Baclofen at the doses of 2, 4 and 8 mg/kg, s.c. induced gastric ulceration in a dose-dependent manner in the hypothermic (body temperature: 28-30 degrees C) rat. Duodenal ulcers were also observed in about 80% of the hypothermic animals treated with the highest dose of baclofen. Baclofen, even at 8 mg/kg, s.c., however, failed to induce gastric ulceration in the normothermic (body temperature: 37-38 degrees C) rat. Histamine, at the secretagogue dose causing acid secretion as potently as 8 mg/kg of baclofen, induced gastric ulcers in both the hypothermic and the normothermic rats. These results indicate that the ulcerogenic effect of baclofen is closely related to the thermoregulation mechanism and may provide important clues for clarifying the pathophysiology of gastroduodenal ulcers induced by hypothermic treatments such as water-immersion stress ulcers or cold exposure ulcers.

Animals↗
PubMed1990

Direct evidence indicating that a GABA-mimetic stimulates acid secretion through central mechanisms.

Acid secretagogue effects of central and peripheral baclofen were compared in the rat. Intravenously (0.1-1.0 mg/kg) and intracerebroventricularly (0.1-1.0 micrograms) administered baclofen augmented acid output to the same degree in a dose-dependent manner. GABA microinjected into the lateral hypothalamus (200 and 400 micrograms) significantly increased acid output. These support the proposal that baclofen stimulates acid secretion through central mechanisms and also the possible role of GABA in central regulation mechanisms of acid secretion.

Anesthesia↗