[Criteria for the clinical evaluation of antimicrobial drugs in neonates].
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Anti-Infective Agents↗
Biomedical subjects
R Fujii
Publications and source records attributed to R Fujii.
Pharmacokinetics and clinical effects of cefozopran in pediatric patients.
An investigation was made into pharmacokinetics and clinical effects of the newly-developed cephem antibiotic for injection, cefozopran (SCE-2787, CZOP), in pediatric patients. In 26 patients in whom pharmacokinetics were investigated, peak serum concentrations of CZOP administered at doses of 10, 20 and 40 mg/kg by i.v. injection were 21.3 +/- 10.0 (mean +/- standard deviation), 51.0 +/- 9.9 and 68.3 +/- 0.7 micrograms/ml, respectively. Serum concentrations at 6 hours after administration were 2.9 +/- 1.7, 2.3 +/- 0.9 and 4.6 +/- 2.6 micrograms/ml, with the levels roughly above MIC90s for dominating pathogenic bacteria being maintained until 6 hours after treatment. Urine concentrations were in the range between 200 and 560 micrograms/ml at 4 to 6 hours after dosing. Cumulative urine excretion accounted for 70 to 80% of dose. In 11 patients in whom pharmacokinetic investigations were performed, peak serum concentrations of CZOP administered at doses of 10, 20 and 40 mg/kg by 30-min. i. v. drip infusion were 37.1, 66.3 +/- 25.5 and 95.7 +/- 8.9 micrograms/ml, respectively. Serum concentrations at 6 hours after dosing were 1.6, 2.3 +/- 0.8 and 3.0 +/- 0.4 micrograms/ml, respectively, with the levels above MIC90s for dominating pathogenic bacteria also being maintained until 6 hours after administration. Urine concentrations were 190 micrograms/ml or more until 8 hours after dosing and the cumulative urinary excretion accounted for 50 to 70% of dose. In 9 patients with meningitis in whom CZOP penetration into cerebrospinal fluid was investigated, concentrations in the fluid of the compound i.v. injected at doses from 40 to 53 mg/kg were in the range between 1.6 and 43.4 micrograms/ml exceeding MICs for pathogenic bacteria at 1 to 1.5 hours after dosing. In all of the 38 patients in whom pharmacokinetic investigations and clinical evaluations were performed, CZOP was good to excellent (excellent in 22 patients and good in 16 patients). Also in bacteriological evaluations, all of the 31 strains of investigated pathogenic bacteria were eradicated. The clinical efficacy rates for the 335 subjects for clinical evaluations were 97.0% (195/201) for patients in whom pathogenic bacteria were detected (group A), and 95.5% (128/134) for patients in whom no pathogenic bacteria were detected (group B). In bacteriological evaluations, the eradication rates of Gram-positive and Gram-negative bacteria were 96.3% (77/80) and 94.5% (155/164), respectively, with the eradication rate in total being 95.1% (232/244). Safety investigations were performed in 364 patients. Adverse reactions were reported in 11 patients (3.0%), including diarrhea (aqueous stool and soft stool) in 7 patients (1.9%) and drug rash (rash, eruption and wheal) in 4 patients (1.1%). Abnormal laboratory test values were noted in 54 patients, including eosinophilia in 20 patients (6.3%) and elevated GPT in 20 patients (6.3%). The adverse reactions and abnormal laboratory test values were not serious, disappearing or improving during the continued treatment period or as a result of discontinuation of the treatment. Serum and urine concentrations of CZOP, when administered by i.v. injection and 30-min, i.v. drip infusion at doses of 10, 20 and 40 mg/kg, were higher than the MICs for pathogenic bacteria until 6 hours after dosing. The drug also showed favorable penetration into cerebrospinal fluid. It was therefore considered that CZOP was a highly useful drug for the treatment of pediatric infections with sufficient bacteriological and clinical efficacy when administered at a dose of 40 to 80 mg/kg three to four times daily.
Bacteria↗
Rapid incorporation of carbon-11-labeled diacylglycerol as a probe of signal transduction in glioma.
We have synthesized and characterized a positron-emitting carbon-11-labeled 1,2-diacylglycerol to study phosphoinositide turnover in tumor cells. Rapid incorporation of the 1,2-diacylglycerol was observed in the C6 glioma cell line. The incorporated lipid fraction consisted chiefly of phosphoinositide pool and another phospholipid pool in the proliferative state. When the state was inhibited by (-)-3D-3-deoxy-3-fluoro-myo-inositol, incorporation into the phosphoinositide pool decreased selectively. This suggested that phosphoinositide turnover is the leading regulator of tumor proliferation potential. On the basis of the concept of carbon-11-labeled 1,2-diacylglycerol as a specific probe for visualizing the tumor signal transduction in vivo, we obtained proliferating images of implanted C6 glioma cells in the rat brain by autoradiography and visualized the proliferation signal in human glioma by positron emission tomography.
Animals↗
The expression of thymidine phosphorylase and thrombomodulin in human colorectal carcinomas.
Thymidine phosphorylase (dThdPase) is an enzyme involved in pyrimidine nucleoside metabolism. dThdPase activity is increased in several types of malignant tumors. Recently, we demonstrated that dThdPase is identical to platelet-derived endothelial cell growth factor (PD-ECGF) and that dThdPase has angiogenic activity. We measured dThdPase activity and the level of thrombomodulin (TM) as a marker for endothelial cells in colorectal carcinomas and adjacent normal tissues from 21 patients, and in adenomas from 13 patients. The average dThdPase activity of colorectal carcinomas (11.58 +/- 6.30 nmol/100 micrograms protein/h) was significantly higher than that of adenomas (8.57 +/- 4.14 nmol/100 micrograms protein/h) or normal tissues (4.89 +/- 3.16 nmol/100 micrograms protein/h). In immunohistochemical study, the expression of dThdPase was observed more frequently in colorectal carcinomas than in adenomas or normal mucosas. The amount of TM in colorectal carcinomas (8.32 +/- 5.07 ng/100 micrograms protein) was significantly higher than that of adenomas (4.51 +/- 4.49 ng/100 micrograms protein) or normal tissues (3.51 +/- 2.78 ng/100 micrograms protein). dThdPase activity in human colorectal carcinomas, adenomas and normal tissues was significantly correlated with the expression of TM in these tissues. These results indicate that the expression levels of both dThdPase and TM in colorectal carcinomas are higher than those in colorectal adenomas and normal tissues and suggest that dThdPase may be involved in angiogenesis in human colorectal carcinomas, adenomas and normal tissues.
Colorectal Neoplasms↗
Rational use of oral antibiotics for pediatric infections.
We carried out a survey in Japan to investigate compliance among children given oral antibiotics in an outpatient setting. The results of our survey revealed that, in Japan, approximately one-quarter of patients did not take their full course of antibiotics. Reasons for unsupervised self-discontinuation included: (1) the parent or guardian judged the infection to be cured; (2) the child refused to take the drug; and (3) the appearance of side effects. Causative organisms often involved in respiratory infections experienced in out-patient medicine include pneumococci, streptococci, staphylococci, Haemophilus influenzae, Moraxella (Branhamella) catarrhalis and Mycoplasma pneumoniae. The beta-lactams are effective against all of these bacterial species, with the exception of M. pneumoniae. We conducted a survey of beta-lactam antibiotics currently on the Japanese market and compared them to other oral antibiotics used to treat respiratory infections. Ease of administration, based on the incidence of adverse effects, particularly diarrhea, the dosage form, taste, dosage per administration and the number of doses required per day, are reported.
Administration, Oral↗
[The use of polymerase chain reaction method for the detection of Rickettsia tsutsugamushi in wild rodents].
We studied the applicability of polymerase chain reaction (PCR) method for the detection of R. tsutsugamushi in wild rodents. The PCR method which amplified the gene coding for the group-specific antigen of R. tsutsugamushi was used in this study. Specific PCR products (88 bp) were obtained with the DNAs from three reference strains (Gilliam, Karp, and Kato) and two cell culture adapted field isolates (KN-1 and GJ-1). The minimum number detectable by the PCR method was estimated to be 1.3 copies of rickettsial genome. In a study with experimentally infected mice, the PCR method could detect rickettsial DNA in one of two infected mice at four months after inoculation. Thereafter, fifty five wild rodents were captured in five areas of Okayama Prefecture, and R. tsutsugamushi DNA was detected, by the PCR method, by amplifying DNA from the spleen of each rodent. The rickettsia was also isolated from the same rodents by the mouse inoculation method. By the PCR method, rickettsia DNAs could be detected in 12 of 13 rodents from which the rickettsiae were isolated, and in 10 of 42 rodents from which no rickettsiae were isolated. These findings indicate that the PCR method is a simple and specific procedure to detect R. tsutsugamushi in wild rodents. On the other hand, the results of the PCR method demonstrated that the middle area of Okayama Prefecture was highly (44-81%) contaminated with R. tsutsugamushi.
Animals↗
Thrombolytic effect of nattokinase on a chemically induced thrombosis model in rat.
Nattokinase is a new fibrinolytic enzyme which cleaves directly cross-linked fibrin in vitro. In this study, we investigated the thrombolytic effect of nattokinase on a thrombus in the common carotid artery of rat in which the endothelial cells of the vessel wall were injured by acetic acid. When a section of occluded vessel was stained for CD61 antigen by immunofluorescence utilizing a monoclonal antibody, the antigen was localized around the surface of the occluded blood vessels. This result suggests that the occlusive thrombosis was caused by platelet aggregation. In addition, thrombolysis with urokinase (UK; 50000 IU/kg, i.v.) or tissue plasminogen activator (tPA; 13300 IU/kg, i.v.) in our model was observed to restore the blood flow over a 60 min monitoring period. The results indicate that our chemically induced model is useful for screening and evaluating a thrombolytic agent. We evaluated the thrombolytic activity of nattokinase using this model and compared it with fibrino(geno)lytic enzyme, plasmin or elastase. On a molar basis, the recovery of the arterial blood flow with nattokinase, plasmin and elastase were 62.0 +/- 5.3%, 15.8 +/- 0.7% and 0%, respectively. The results indicate that the thrombolytic activity of nattokinase is stronger than that of plasmin or elastase in vivo.
Animals↗
[Pharmacokinetic and clinical studies with azithromycin (fine granule) in the pediatric field. Pediatric Study Group of Azithromycin].
Azithromycin (AZM) in 10% fine granules, a newly developed azalide antibiotic, was administered at a standard dose of 10 mg/kg once daily for 3 to 5 days (89.5% received 3 day administration) to children with infectious diseases and the efficacy and the safety of AZM were investigated. In addition AZM concentrations were determined in blood samples from 18 patients and in urine samples from 17 patients to examine o pharmacokinetic characteristics of AZM. 1. Absorption and excretion: Cmax's in 16 patients who received 10 mg/kg and 2 patients who received 20 mg/kg were 0.29 +/- 0.24 micrograms/ml and 0.75 micrograms/ml, respectively, while T 1/2's were 42.0 +/- 11.8 hours for the former and 51.3 hours for the latter. AUC(0 to approximately infinity)'s were 10.72 +/- 5.00 micrograms x hr/ml in the former and 28.83 micrograms x hr/ml in the latter. Urinary concentrations of AZM peaked at 48 to 72 hours after the administration of 10 mg/kg AZM in 14 patients, while it peaked at 24 to 48 hours in the patients who received 20 mg/kg. Urinary recovery rates in the first 120 hours after the start were 9.1 +/- 2.6% for 10 mg/kg and 10.8 +/- 3.4% for 20mg/kg. 2. Clinical efficacy: The study received 619 entries and 564 cases were evaluated for drug efficacy. The remaining were not evaluated because of dropout or exclusion. The efficacy rate, combining both "Excellent" and "Good" cases was 94.3% in 246 cases where pathogens were identified, classified as Group A. The efficacy rate was 90.7% for the remaining 321 cases, classified as Group B, where causative pathogens were unidentified. The difference between the two groups was no statistical significance. The combined efficacy rate was 92.2%. For the 116 cases where the patients had failed to respond to previous chemotherapies instituted for 3 days or longer, the efficacy rate for AZM was 94.0%. 3. Adverse reactions and abnormal laboratory tests: Incidents of diarrhea, soft stool, skin rashes, or vomiting were found in 15 patients (2.5%) of 596 cases eligible for evaluation. These reactions, however, were all transient and mild to moderate in severity in the 15 patients including 4 patients for whom the treatment was discontinued, all resolved in time. Abnormal changes in laboratory tests were found as follows: decrease in WBC in 23 patients (5.6%), increase in eosinophils in 28 (7.1%), increase in platelet count in 2 (0.5%), decrease in platelet count in 1 (0.3%), elevation of GOT in 3 (0.8%), and elevation of GPT in 6 (1.6%).(ABSTRACT TRUNCATED AT 400 WORDS)
Absorption↗
[Pharmacokinetic and clinical studies with azithromycin (capsule) in the pediatric field. Pediatric Study Group of Azithromycin].
Azithromycin (AZM) in 100 mg capsules, a newly developed azalide antibiotic, was administered at a standard dose of 10 mg/kg once daily for 3 to 5 days (89.9% received 3 day administration) to children with infectious diseases and the efficacy and the safety of AZM were investigated. In addition, AZM concentrations were determined in blood samples from 9 patients and in urine samples from 12 patients to examine pharmacokinetic characteristics of AZM. 1. Absorption and excretion: Cmax was 0.45 +/- 0.28 micrograms/ml, T 1/2 was 52.7 +/- 20.2 hours, and AUC(0 approximately to infinity) was 12.09 +/- 4.93 micrograms.hr/ml in the 9 patients each of whom received 8.5 to 14.3 mg/kg AZM. Urinary concentrations of AZM peaked at 48 to 72 hours after the administration of 8.5 to 14.7 mg/kg AZM in 12 patients and the average urinary recovery rate in 120 hours was 7.3 +/- 2.8%. 2. Clinical efficacy: The study received 139 entries and 119 cases were evaluated for drug efficacy. The remaining were not evaluated because of dropout or exclusion. The efficacy rate combining both "Excellent" and "Good" cases, was 100% for 40 cases in which pathogens were identified, classified as Group A. The efficacy rate was 97.5% for the remaining 79 cases, classified as Group B, where causative pathogens were unidentified. The difference between the two groups was no statistical significance. The combined efficacy rate was 98.3%. For the 31 cases where the patients had failed to respond to the previous chemotherapies instituted for 3 days or longer, the efficacy rate for AZM was 93.5%. 3. Adverse reactions and abnormal laboratory tests: 8 incidents of diarrhea, skin rashes, urticaria, or vomiting were found in 7 patients (5.4%) of 130 cases eligible for evaluation. These reactions, however, were all transient and mild to moderate in severity in the 7 patients including 2 patients for whom the treatment was discontinued, all resolved in time. Abnormal changes in laboratory tests were found as follows: decrease in WBC in 10 patients (9.3%), an increase in eosinophils in 12 (11.4%), an increase in platelet count in 1 (1.0%), an elevation of GOT in 3 (3.1%), an elevation of GPT in 6 (6.2%), and an elevation of LDH in 1 (1.1%). The abnormalities were transient and did not require particular intervention. Moreover, none of the patients indicated clinical signs associated with the abnormal changes of laboratory tests.(ABSTRACT TRUNCATED AT 250 WORDS)
Absorption↗
[Pharmacokinetic and clinical studies of S-1108 in the pediatric field. Pediatric Study Group of S-1108].
S-1108 in granules, a new oral cephem antibiotic, was pharmacokinetically and clinically evaluated in the pediatric field and the following results were obtained. 1. Pharmacokinetics S-1108 was administered at single doses of 2, 3, 4, 6 mg/kg orally and the following results were obtained on Cmax, T 1/2 and AUC, respectively: Cmax: 0.79, 1.03, 1.39, 1.06 micrograms/ml, T 1/2: 1.28 +/- 0.40, 1.27 +/- 0.65, 1.10 +/- 0.29, 1.83 hrs., AUC: 2.65 +/- 0.63, 3.99 +/- 2.77, 5.25 +/- 1.83, 5.15 micrograms.hr/ml. These values indicated a dose-dependent pharmacokinetic behavior. Urinary recovery rates were 12.5-30.0% in the first 8(6) hours after administration. 2. Clinical results The clinical efficacy of S-1108 was evaluated in 456 patients with various infections. S-1108 was administered at a dose of 2-4 mg/kg three time a day to most patients. The overall clinical efficacy rate was 95.0%. In 294 cases with identified causative pathogen, the clinical efficacy rate was 96.9%, and the bacteriological eradication rate was 89.0%. Side effects occurred in 18 (3.23%) of 558 patients subjected to safety analyses. The main side effect was diarrhea but those side effects were mild and reversible. Abnormal laboratory test results were observed in 25 cases, (eosinophilia and elevated GOT and GPT). These abnormalities were not dose-dependent and also seen with other cephems to a similar extent. No particular and serious problems were associated with administration of this drug. Based on the above results, S-1108 is considered to be very useful at a standard dose of 2-4 mg/kg t.i.d. against most infections encountered in the pediatric field out-patient clinic.
Administration, Oral↗
[Clinical evaluation of a new oral penem, SY5555, in the pediatric field].
A new oral penem antibiotic, SY5555, was evaluated for its safety and efficacy in 35 children with various bacterial infections. SY5555 was effective in 100% of scarlet fever, pharyngotonsillitis, pneumonia, otitis media, bacterial diarrhea, urinary tract infections and skin and soft tissue infections. The etiologic bacteria were eradicated except Salmonella sp. Side effects were observed in 3.5% cases; one was diarrhea and Candida dermatitis, one was loose stool, and one was Candida dermatitis. From these data, SY5555 is thought to be a safe and effective antibiotic in the pediatric field. Regular dose of suspension preparation is 15 mg/kg/day in 3 divided dosages, and when needed the dose may be doubled.
Administration, Oral↗
[Carbon-11 labeled diacylglycerol for signal transduction imaging by positron CT: evaluation of the quality and safety for clinical use].
To elucidate the synaptic transmission in the neural system, we have been developing fundamental studies for intracellular signaling. For clinical application of carbon-11 labeled diacylglycerol (1-[1-11C]butyryl-2-palmitoyl-rac-glycerol: 11C-DAG) using positron emission computed tomography (PET), we evaluated the quality and the safety of 11C-DAG as the solution for injection. As a result, 11C-DAG was synthesized within 50 minutes, including the preparation step for injection. The half life time and energy spectrum of 11C-DAG were the same as the physical character of carbon-11, and other radioisotopes were not detected. In the quality control, 11C-DAG solution was negative in the examination of bacterial contamination and the pyrogen test in three successive synthesis procedures. In the acute toxicity test by administration of 11C-DAG and 100 mumol/kg of non-radioactive DAG to the rat intravenously, the systemic condition of the rat was not changed and no abnormalities were found in any organ 24 hours after administration. These findings indicated the safety of 11C-DAG solution. Clinical application of 11C-DAG using positron emission tomography may be useful to elucidate the dysfunction of intracellular signaling in disorders of higher cortical function such as Alzheimer disease.
Animals↗
[Comprehensive evaluation of pharmacokinetic and clinical studies on tazobactam/piperacillin in pediatric field].
To evaluate the pharmacokinetic and clinical effects of the newly developed combination antibiotic tazobactam/piperacillin (TAZ/PIPC, YP-14) on various infections in pediatric field, a study group was organized, and a joint research by 17 institutions and their related hospitals was conducted. Informed consents of subjects were obtained prior to the study. The results obtained in this study are as follows: 1. Blood concentration and urinary excretion Pharmacokinetics of TAZ/PIPC was studied in children at doses of 25 and 50 mg/kg through intravenous injection or intravenous drip infusion. With intravenous injection, maximum blood concentrations (Cmax's) of TAZ and PIPC were achieved 5 minutes after the administration. Cmax's of TAZ were 26.9 micrograms/ml with 25 mg/kg and 45.1 micrograms/ml with 50 mg/kg, and those of PIPC were 131.0 and 199.6 micrograms/ml, respectively. Values of the total area under the blood concentration curve (AUC's) of TAZ were 14.2 micrograms.hr/ml with 25 mg/kg and 26.1 micrograms.hr/ml with 50 mg/kg, and those of PIPC were 64.0 and 112.8 micrograms.hr/ml, respectively; thus dose dependency was observed with both TAZ and PIPC. The Cmax's of desethyl piperacillin (DEt-PIPC), the active metabolite of PIPC, achieved at 60 minutes after administration, were 1.2 and 2.0 micrograms/ml, respectively. The AUC's of DEt-PIPC were 2.6 and 4.2 micrograms.hr/ml, respectively. The half-lives (T 1/2's) of TAZ were 0.60 and 0.54 hour, respectively, and those of PIPC were 0.62 and 0.65 hour, respectively. In the first 6 hours after the initiation of administration, the cumulative recovery rates of TAZ in the urine were 46.7 and 56.0% respectively, those of PIPC were 46.1 and 57.2%, respectively, and those of DEt-PIPC were 5.9 and 3.0%, respectively. With intravenous drip infusion, the Cmax's of both TAZ and PIPC were achieved at the completion of drip; the Cmax's of TAZ were 12.1 micrograms/ml with 25 mg/kg and 28.9 micrograms/ml with 50 mg/kg, and those of PIPC were 54.6 and 137.9 micrograms/ml, respectively. The AUC's of TAZ were 11.6 micrograms.hr/ml with 25 mg/kg and 25.6 micrograms.hr/ml with 50 mg/kg, and those of PIPC were 49.0 and 117.2 micrograms.hr/ml, respectively; thus dose dependency was observed with both TAZ and PIPC. Cmax's of DEt-PIPC, achieved at 60 minutes after completion of drip, were 0.9 and 1.7 micrograms/ml, respectively. The AUC's of DEt-PIPC were 2.0 and 3.8 micrograms.hr/ml, respectively. The half-lives (T 1/2's) of TAZ were 0.59 and 0.62 hour, respectively, and those of PIPC were 0.58 and 0.57 hour, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)
Adolescent↗
Adenosine triphosphate-dependent transport of leukotriene C4 by membrane vesicles prepared from cisplatin-resistant human epidermoid carcinoma tumor cells.
BACKGROUND: Cisplatin accumulation is decreased in many cisplatin-resistant cells. An active efflux pump for cisplatin exists in cisplatin-resistant human epidermoid carcinoma cells (called KB cells). A previous study has suggested that the adenosine triphosphate (ATP)-dependent glutathione S-conjugate export pump (GS-X pump), which exports the bis-(glutathionato)-platinum (II) (GS-platinum) complex, could contribute to cellular resistance to cisplatin. PURPOSE: In this study, we examined whether the active efflux pump for cisplatin in the cisplatin-resistant KB cells is the GS-X pump and tested its activity by using an endogenous substrate, [3H]leukotriene C4 ([3H]LTC4). METHODS: Membrane vesicles were prepared from KB-3-1 (clone from parental KB cells) cells and from cisplatin-resistant KCP-4 (a mutant clone derived from KB-3-1 cells) cells. Using a filtration technique, we measured the uptake and transport of [3H]LTC4, a substrate for the GS-X pump, into membrane vesicles at 37 degrees C. RESULTS: The uptake of [3H]LTC4 in the membrane vesicles from both the KB-3-1 and KCP-4 cells was ATP-dependent. In contrast, the ATP-dependent transport of [3H]LTC4 was observed only in KCP-4 membrane vesicles but not in KB-3-1 membrane vesicles. The ATP-dependent transport was vanadate sensitive and was inhibited by GS-platinum complex but only marginally by cisplatin and glutathione and not by vincristine or verapamil. The nucleotide triphosphates, guanosine triphosphate, cytidine triphosphate, uridine triphosphate, and deoxythymidine triphosphate could be substituted for ATP but were less efficient. A nonhydrolyzable ATP analogue, adenosine 5'-(beta,gamma-methylene) triphosphate, was not effective. CONCLUSIONS: The transport of LTC4 in membrane vesicles prepared from KCP-4 cells was facilitated by an ATP-dependent pump that appeared very similar to the GS-X pump. IMPLICATIONS: Our study suggests that the GS-X pump is involved in the decreased accumulation of cisplatin in KCP-4 cells.
Adenosine Triphosphate↗
Active efflux system for cisplatin in cisplatin-resistant human KB cells.
Mutants, KCP-4 and PC-5, resistant to an anticancer agent, cisplatin, were selected in multiple steps from human epidermoid KB carcinoma cells and human prostate PC-3 carcinoma cells, respectively. KCP-4 and PC-5 were 63 and 10 fold more resistant to cisplatin than the parental cells, respectively. KCP-4 cells exhibited increased resistance to cisplatin analogues and were also slightly cross-resistant to melphalan, cyclophosphamide, mitomycin C and methotrexate. KCP-4 cells were not cross-resistant to doxorubicin, daunorubicin, vincristine or CdSO4. The accumulations of cisplatin in KCP-4 cells and PC-5 in medium containing 50 microM cisplatin were approximately 20% of those in the parental cells. Revertant analysis suggested that a defect in cisplatin accumulation may be related to cisplatin resistance in PC-5 cells. The uncoupling agent of oxidative phosphorylation, 2,4-dinitrophenol, increased the accumulation of cisplatin in KCP-4 and cisplatin-resistant human prostate carcinoma PC-5 cells to nearly the same level as in their parental KB-3-1 and human prostate carcinoma PC-3 cells without 2,4-dinitrophenol, but did not increase accumulation in KB-3-1 and PC-3 cells. Addition of glucose in the medium inhibited the enhancement of cisplatin accumulation in KCP-4 cells by 2,4-dinitrophenol. Enhanced active efflux of cisplatin from KCP-4 cells was observed. A cell-cell hybridization test showed that the cisplatin resistance and the accumulation defect behaved as codominant traits. These data suggest that an active efflux system for cisplatin exists in cisplatin-resistant KCP-4 cells.
Biological Transport, Active↗
Pharmacological profiles of the subtypes of muscarinic cholinoceptors that mediate aggregation of pigment in the melanophores of two species of catfish.
Using selective antagonists, including pirenzepine, adiphenine, AF-DX 116, gallamine, and 4-DAMP, we attempted to characterize the muscarinic cholinoceptors on the melanophores of the translucent glass catfish Kryptopterus bicirrhis and the mailed catfish Corydoras paleatus. The M3 receptor-selective antagonist, 4-DAMP, potently inhibited the acetylcholine-induced aggregation of pigment in both species. It appeared, therefore, that the receptors that mediated the cholinergically evoked aggregation of melanosomes in these species were of the M3 muscarinic subtype.
Acetylcholine↗
[A hemodynamic comparison of cardiovascular stress responses during mental arithmetic and reaction time tasks].
The primary purpose of this study was to examine the covariation between preload (PL) and other cardiovascular stress responses during mental arithmetic (MA) and reaction time (RT) tasks. PL, stroke volume (SV), cardiac output (CO) and pre-ejection period (PEP) were obtained using impedance cardiography. Mean blood pressure (MBP) was measured by the vascular unloading method. Thirty-one male college students were given both MA and RT tasks with a counterbalanced order. Results indicated significant differences in heart rate reactivity which seems to provide evidence for a stronger vagal withdrawal in MA. Changes in CO and MBP were identical in these two tasks which might have resulted from a compensatory change in PL and SV. Specificity of PEP for the increased beta-adrenergic activity was supported by the correlation pattern among PL, MBP and PEP. The results were discussed in the context of cardiovascular regulating mechanisms.
Adolescent↗
[Cardiac vagal withdrawal during stressful tasks estimated by the baroreflex sensitivity and respiratory sinus arrhythmia].
The primary purpose of this study was to compare the changes in baroreflex sensitivity (BRS) with those in respiratory sinus arrhythmia (RSA) during mental arithmetic (MA) and reaction time (RT) tasks. BRS was assessed by the sequence scanning method (Bertinieri et al., 1988) combined with the vascular unloading technique that enables beat-by-beat measurement in systolic blood pressure. Twenty-eight male college students were given both MA and RT tasks with the order counterbalanced. Results indicated significant differences in BRS and RSA reactivity that seems to be evidence for a stronger vagal withdrawal in MA. Reactivity in RSA was correlated more closely with respiratory variables (respiration rate, tidal volume, and end-tidal CO2) than in BRS. These findings suggest that BRS is more suitable for estimating cardiac parasympathetic control because of its greater independence from respiratory activity. The results were discussed concerning the patterning of cardiorespiratory stress responses.
Adolescent↗