Two pyridine analogues with more effective ability to reverse multidrug resistance and with lower calcium channel blocking activity than their dihydropyridine counterparts

Four pyridine analogues and their dihydropyridine counterparts were examined for their ability to reverse drug resistance in a multidrug-resistant human carcinoma cell line, KB-C2. Two pyridine analogues were more able to reverse drug resistance than their dihydropyridine counterparts. The other two pyridine analogues had an effect on drug resistance similar to their dihydropyridine counterparts. The calcium channel-blocking activity of all the pyridine analogues was considerably lower than that of the dihydropyridine analogues. Of the pyridine analogues, 2-[4-(diphenylmethyl)-1-piperazinyl]ethyl 5-(trans-4,6-dimethyl-1,3,2-dioxaphosphorinan-2-yl)-2,6-dimethyl-4 -(3- nitrophenyl)-3-pyridinecarboxylate P-oxide (PAK-104P) was the most effective in reversing multidrug resistance. PAK-104P (1 and 5 microM) completely reversed the drug resistance in KB-8-5 and KB-C2 cells, respectively. The reversing effect of PAK-104P was greater than that of other multidrug resistance-reversing agents, cepharanthine, verapamil, nimodipine, and nicardipine. PAK-104P at 1 microM increased about 10-fold the accumulation of vinblastine in KB-C2 cells, whereas verapamil at the same concentration increased the accumulation about 2-fold. The inhibition of [3H]azidopine photolabeling of P-glycoprotein by the pyridine and dihydropyridine analogues except 2-[methyl(phenyl-methyl)amino]ethyl 4-(2-chlorophenyl)-5-(4-methyl-1,3,2-dioxaphosphorinan-2-yl)-1,4-d ihydro-2,6- dimethyl-3-pyridinecarboxylate P-oxide correlated with the reversing of drug resistance by the analogues. Some newly synthesized pyridine analogues seemed to have lower calcium channel-blocking activity and more potent resistance-reversing ability than verapamil and other calcium channel blockers.

[Detection of two Shiga-like toxins from Escherichia coli O157:H7 isolates by the polymerase chain reaction method]

Fourteen isolates of E. coli O157:H7 and five isolates of S. dysenteriae type-1 were examined by polymerase chain reaction (PCR) for the structural genes (slt-I or slt-II), encoding Shiga-like toxins (SLTs). The two primer pairs (V1; 5'AGTTAATGTGGTGGCGAA and V2; 5'GACTGCGTCAGTGAGGTT for SLT-I, V3; 5'TTCGGTATCCTATTCCCG and V4; 5'TCTCTGGTCATTGTATTA for SLT-II) used were of the same positions representing the DNA sequence covering 471bp of the slt-I or slt-II. A 5-microliter portion of boiled bacterial culture broth was used as template DNA in a PCR-reaction mixture of 50 microliters. Two classes, slt-I alone or both slt-I and slt-II, were recognized in E. coli strains. All of S. dysenteriae type-1 strains examined contained slt-I alone. Our results indicate that PCR using these primer pairs is a simple, rapid, sensitive, and specific method and suitable for use in routine diagnostic microbiology laboratories.

Ammonia production as a virulence expression by Mycoplasma salivarium

Rabbits were inoculated intracutaneously with M. salivarium (ATCC 23064) cells. The size of the resulting swelling was significantly larger in 1) the sites inoculated with viable cells (7.5 x 10(9) CFU) suspended in a medium with arginine (arginine medium) than in those inoculated with killed cells, and in 2) those inoculated with cells suspended in arginine medium than with cells suspended in arginine-free medium. The swelling was enhanced when rabbits had previously been immunized with the organism. This effect was concluded to be due to ammonia which the organism produced by the hydrolysis of arginine through the arginine-dihydrolase pathway.

[Does induction with midazolam decrease stress response during anesthesia?]

The effects of midazolam on stress response during surgery compared with thiamylal were studied. Twelve patients were divided into 2 groups at random; midazolam group and thiamylal group. Anesthesia was induced with midazolam 0.2 mg.kg-1 or thiamylal 4 mg.kg-1 in each group, and maintained with O2 2 l.min-1, N2O 4 l.min-1 and enflurane. The plasma concentration of catecholamine was measured at preinduction, 10, 30, 60, 120 and 180 minutes after intubation. No significant differences were seen between 2 groups in plasma concentration of catecholamine. In midazolam group, plasma concentration of epinephrine decreased significantly 10 minutes after intubation as compared with preinduction level. The plasma concentration of norepinephrine in midazolam group tended to decrease. In thiamylal group, plasma concentration of norepinephrine tended to increase and increased significantly at 120 and 180 minutes after intubation as compared with preinduction level. These results suggest that induction with midazolam suppresses stress response during anesthetic induction and surgery more intensely than induction with thiamylal.

Influence of electrical stimulation of the hypothalamus on ovarian steroidogenesis in hypophysectomized and adrenalectomized rats

The effects of electrical stimulation of the lateral hypothalamic area (LHA), periventricular arcuate nucleus (ARC) and ventromedial hypothalamic nucleus (VMH) on the rates of 14C transfer from 14C-1 acetate into ovarian steroids in ovarian slices of hypophysectomized and adrenalectomized (H-A) rats were investigated. The 14C transfer rates into estrogen and 20 alpha-hydroxypregn-4-en-3-one (20 alpha-OH-P) were decreased by LHA stimulation. The stimulation of the ARC and VMH increased the rates of 14C transfer into estrogen, progesterone and 20 alpha-OH-P. From these results, it might be suggested that these hypothalamic structures were involved in the regulation of ovarian steroidogenesis without participation of the pituitary and adrenal.

[Midazolam for rapid sequence induction]

We compared midazolam 0.2 mg.kg-1 and fentanyl 50 micrograms with thiamylal 4 mg.kg-1 for rapid sequence induction. We could use midazolam safely in patients with bronchial asthma or drug allergy. There was no difference in time from the beginning of induction to intubation between midazolam treated group and thiamylal treated group. Changes in systolic as well as diastolic blood pressure and heart rate during 2 hours from intubation were smaller in midazolam treated group than in thiamylal treated group. In midazolam treated group, no arrhythmias were observed at the time of intubation. We could reduce the amount of anesthetics in midazolam treated group during 2 hours from intubation. From the results mentioned above, we conclude that midazolam is a useful agent for rapid sequence induction.

Influence of incomplete bile duct obstruction on the occurrence of cholangiocarcinoma induced by diisopropanolnitrosamine in hamsters

This study was performed to clarify the influence of incomplete bile duct obstruction (IBDO) on the occurrence of cholangiocarcinoma, using Syrian golden hamsters. These hamsters underwent simple laparotomy (SL) or IBDO at the choledochus and received diisopropanolnitrosamine (DIPN) once weekly for 20 weeks (SL-DIPN or IBDO-DIPN groups). Histological examination in the liver showed increased bile ductules, goblet cell metaplasia of the bile duct epithelium and cholangiocarcinoma in the two groups. The occurrence rates of cholangiocarcinoma at 20 weeks were 35% in the SL-DIPN group and 89% in the IBDO-DIPN group (p less than 0.01). The mean numbers of tumors per hamster in the IBDO-DIPN group were significantly higher than those in the SL-DIPN group (p less than 0.01). Regarding the composition of bile acid in the intraductal bile, both groups revealed an increase in primary bile acid, consisting of more than 80% of cholic acid. Bacteria were detected in the group with IBDO throughout the whole course. These results suggest that IBDO has an influence as promoter on the occurrence of DIPN-induced cholangiocarcinoma.

Neural mechanisms underlying the action of primer pheromones in mice

Our electrophysiological experiments in female mice have provided evidence that electrical stimulation of the accessory olfactory bulb orthodromically excites a subpopulation of tuberoinfundibular arcuate neurons by way of the amygdala. The present study shows that half of such neurons are identified as dopaminergic by examining the effectiveness of infusing 6-hydroxydopamine and 5,7-dihydroxytryptamine locally into the median eminence in blocking their antidromic response. Further attention is focused on excitatory amino acid receptors within the amygdala and the amygdaloid pathway that mediate the accessory bulb-induced excitation of tuberoinfundibular arcuate neurons. The excitatory transmission was reversibly blocked by intra-amygdala infusion (3 nmol) of the excitatory amino acid antagonists kynurenic acid, D,L-2-amino-5-phosphonovalerate, gamma-D-glutamylaminomethylsulphonate and D,L-2-amino-4-phosphonobutyrate. Intra-amygdala infusions (3 nmol) of N-methyl-D-aspartate and kainate markedly enhanced the firing activity of tuberoinfundibular arcuate neurons with excitatory inputs from the accessory bulb, whereas similar infusions of quisqualate were without effect Intra-stria terminalis infusions of the local anaesthetic lignocaine completely abolished the excitatory transmission in all the cells tested. Furthermore, tuberoinfundibular arcuate neurons stimulated from the accessory bulb were also orthodromically stimulated from the stria terminalis with a shorter latency. These studies demonstrate that the projections of the accessory olfactory bulb activate excitatory amino acid receptors within the amygdala and subsequently the stria terminalis route, thereby causing excitation of tuberoinfundibular dopaminergic arcuate neurons. This functional pathway can account for the reproductive effects so far described as a consequence of vomeronasal chemoreception.

An immunological study of tricalcium phosphate supplied by three different manufacturers

Antigenicity of tricalcium phosphate (TCP) ceramics which were supplied by two Japanese manufacturers and a manufacturer of United States was studied by means of delayed skin reactions in guinea pigs. Skin reactions were elicited 13 days after being immunized by intradermal injection of the ceramics into the dorsal flanks of guinea pigs. After 24 and 48 hr, these reactions were assessed by measuring the diameter of the erythema, the degree of hemorrhaging and its induration. Antigenicity was not detected in the TCP obtained from the Asahi Optical Co., Ltd. and the Kyocera Corporation by means of skin reactions. In contrast, TCP from Miter, Inc. (Synthograft) raised a delayed type hypersensitivity (DTH) 24 hr after antigen elicitation. The reaction appeared to be based on tuberculin type and Jones-Mote type of reactions. Arthus reactions were not observed in either the normal groups or groups immunized with TCP.

[Bone scintigraphy in evaluation of the effect of renal transplantation in patients with renal osteodystrophy]

Bone scintigraphy before and after renal transplantation was studied in 14 patients with renal osteodystrophy. The radionuclide distribution patterns visualized on the images before transplantation were classified into two groups; one group with markedly increased tracer uptake throughout the whole skeleton, especially in the skull, another group with prominent tracer uptake in the soft tissues. These abnormal tracer accumulations improved after renal transplantation. Bone scintigraphy before and after renal transplantation provides useful information concerning the follow-up of patients with renal osteodystrophy.

[Bone scintigraphy in evaluation of the effect of renal transplantation in the patients with renal osteodystrophy]

Bone scintigraphy before and after renal transplantation was studied in 10 patients with renal osteodystrophy. The hemodialyses, which resulted in renal osteodystrophy, were maintained for years in all cases before renal transplantation. The radionuclide distribution patterns visualized on the images before transplantation were classified into two groups, that is, one group with markedly increased tracer uptake throughout the whole skeleton, especially in the skull, another group with prominent tracer uptake in the soft tissues. These abnormal increased tracer accumulation improved after renal transplantation. Bone scintigraphy before and after renal transplantation brings about a useful information concerning the follow-up of the patients with renal osteodystrophy.

Correlation between reversing of multidrug resistance and inhibiting of [3H]azidopine photolabeling of P-glycoprotein by newly synthesized dihydropyridine analogues in a human cell line

Ten synthetic dihydropyridine analogues were investigated for their ability to reverse drug resistance in a multidrug-resistant human carcinoma cell line, KB-Cl. Four dihydropyridine analogues completely reversed the resistance, three lowered the resistance, and three had little effect. The radioactive photoactive dihydropyridine calcium channel blocker, [3H]azidopine, photolabels P-glycoprotein in membrane vesicles from KB-Cl cells. This photolabeling was almost completely inhibited by excess dihydropyridine analogues that reversed or lowered drug resistance. In contrast, the labeling was not significantly inhibited by analogues that do not reverse resistance. Among other reversing agents, cepharanthine and reserpine inhibited the [3H]azidopine photolabeling, but thioridazine did not. N-Solanesyl-N,N'-bis(3,4-dimethoxybenzyl)ethylenediamine slightly inhibited the labeling at 100 microM. An anticancer agent, vinblastine, also inhibited the labeling. The correlation between the reversing of the drug resistance and the inhibition of the [3H]azidopine photolabeling of P-glycoprotein by dihydropyridine analogues suggests a role for P-glycoprotein in multidrug resistance and also the reversing of the resistance by dihydropyridine analogues.

Preparation of Mycoplasma hyopneumoniae antigen for the enzyme-linked immunosorbent assay

Methods of preparation of Mycoplasma hyopneumoniae antigens for the enzyme-linked immunosorbent assay to detect specific antibody, and properties of the antigens, are described. The reactivity and specificity of antigen prepared by Sephacryl S-300 column chromatography after treatment of M. hyopneumoniae cells with Tween 20 (S-300 antigen) were superior to those of antigen prepared by Sephadex G-25 column chromatography after treatment with Tween 20, or to lipid antigen. There were no differences among strains MI-3, J and VPP11 of M. hyopneumoniae. The S-300 antigen did not show cross-reactivity against porcine hyperimmune sera produced by M. hyorhinis, M. hyosynoviae, M. hyopharyngis, M. flocculare and Acholeplasma granularum. Antibody was first detected in sera of pigs inoculated intranasally with M. hyopneumoniae at two to four weeks after inoculation and seven to eight weeks after pigs were contact-exposed to the same mycoplasma.

[A molecular basis for multidrug resistance and reversal of the resistance]

Multidrug-resistance is frequently characterized by enhanced drug efflux resulting from a membrane glycoprotein of 170,000 daltons (P-glycoprotein). Analysis of cloned cDNAs for the human MDR 1 gene, whose product is the P-glycoprotein, indicates that P-glycoprotein is an energy-dependent drug-efflux system for cytotoxic hydrophobic anticancer drugs. We have demonstrated that a photoanalog of a reversing agent, SDB-ethylenediamine, specifically binds to P-glycoprotein. The binding site on P-glycoprotein seems to be identical with that of anticancer agents and other reversing agents. On the other hand, the radioactive photoactive dihydropyridine calcium channel blocker, [3H] azidopine, photolabels P-glycoprotein in membrane vesicles from multidrug-resistant cells. This photolabeling is almost completely inhibited by excess dihydropyridine analogs that reverse or lower drug-resistance. In contrast, the labeling is not significantly inhibited by analogs that do not reverse resistance. These results suggest that it may be possible to quickly screen for dihydropyridine analogs that reverse multidrug resistance by measuring the inhibition of [3H] azidopine labeling of P-glycoprotein.

Influence of microinjection of glucagon into the amygdala on hepatic acetate metabolism in rabbits

Glucagon was injected directly into the medial amygdala (AMYG) of rabbits, and changes in hepatic acetate metabolism were studied. The injection of 3 ng glucagon into the AMYG of intact rabbits increased the rates of 14C transfer from 14C-1-acetate into CO2, glucose, ketone bodies, cholesterol ester, free fatty acids and phospholipids but decreased those of 14C transfer into triglyceride. However, the glucagon injection into the AMYG of rabbits with lesions of stria terminals or into the parietal cortex of intact rabbits had no effects on the hepatic acetate metabolism. These observations support the hypothesis that the AMYG is a part of the glucagon-sensitive brain regulator system in the hepatic acetate metabolism.

Excitatory influence of the accessory olfactory bulb on tuberoinfundibular arcuate neurons of female mice and its modulation by oestrogen

The role of the accessory olfactory bulb in conveying pheromonal information to tuberoinfundibular arcuate neurons was examined electrophysiologically in chloral hydrate-anaesthetized, oestrogen (0.5 micrograms in silastic capsules)-treated and untreated ovariectomized Balb/c female mice. Electrical stimulation of the accessory olfactory bulb orthodromically excited part of tuberoinfundibular neurons which were antidromically stimulated from the median eminence and histologically verified as being located within the arcuate nucleus. No inhibitions followed accessory bulb stimulation. The excitatory response to accessory bulb stimulation was reversibly blocked by the local anaesthetic lignocaine infused into the amygdala. The percentage of tuberoinfundibular arcuate neurons responding to accessory bulb stimulation was significantly higher in oestrogen-treated than in untreated animals. There was no difference between the two groups for the antidromic activation threshold, spontaneous firing rate, absolute refractory period or frequency of successful antidromic propagation into the soma of tuberoinfundibular arcuate neurons. In oestrogen-treated preparations, tuberoinfundibular arcuate neurons responsive and unresponsive to accessory bulb stimulation could be distinguished by the frequency of successful antidromic propagation into the soma. These studies demonstrate that olfactory relay neurons in the accessory olfactory bulb act to enhance the activity of a subpopulation of tuberoinfundibular arcuate neurons via the amygdala and that this neural transmission is modulated by oestrogen.

Electrophysiology of neurones projections from the rat A1 noradrenergic region to the medial preoptic/anterior hypothalamic area: lack of effect of the oestrous cycle on their excitability

The neuronal excitability of presumed A1 noradrenergic neurones in the ventrolateral medulla (VLM) which directly project to the medial preoptic/anterior hypothalamic area was analysed in pro-oestrous and metoestrous female rats under urethane anaesthesia. No significant difference was detected between the two groups for the antidromic activation threshold, absolute refractory period, frequency of successful antidromic propagation into the somatodendritic membrane, duration of post-stimulus inhibition, or spontaneous firing rate of these neurones. These results do not support the idea that the neuronal somata of A1 noradrenergic neurones in the VLM show a pro-oestrous increase in excitability during the oestrous cycle, although limitations of the methodology employed do not completely rule out this possibility.

Involvement of the septum in the regulation of paraventricular vasopressin neurons by the subfornical organ in the rat

Extracellular recordings were obtained from 58 phasically active neurosecretory neurons in the hypothalamic paraventricular nucleus (PVN) of urethane-anesthetized male rats. Of these PVN neurons, 39 exhibited an increase and 11 displayed a reduction in ongoing activity following electrical stimulation of the subfornical organ (SFO), while the remaining neurons were unresponsive. Microinjection of the local anesthetic lidocaine into the medial septum reversibly abolished the SFO stimulus-evoked reduction in 7 out of 9 PVN neurons tested, whereas similar injection was without effect on the stimulus-evoked increase in 18 out of 20 PVN neurons tested. These results suggest that the SFO efferents through the medial septum to the PVN exert a predominantly inhibitory influence on the excitability of putative vasopressin (VP)-secreting neurons in the PVN.

The median preoptic nucleus participates in the control of paraventricular vasopressin neurons by the subfornical organ in the rat

Extracellular single-unit activity was recorded from phasically firing neurohypophyseal neurons (n = 41) in the hypothalamic paraventricular nucleus (PVN) of urethane-anesthetized male rats. Electrical stimulation of the subfornical organ (SFO) produced orthodromic long-duration (n = 18) or short-duration (n = 10) excitation or inhibition (n = 8) of the activity of PVN neurons. The long-duration excitatory response of about half (n = 7) the neurons (n = 15) tested was reversibly abolished by microinjection of the local anesthetic lidocaine into the median preoptic nucleus (MnPO), whereas neither the short-duration excitatory (n = 7) nor inhibitory (n = 6) responses were affected. These results suggest that the SFO efferents through the MnPO to the PVN may transmit the neuromodulatory signals which evoke long-duration increases in the excitability of putative vasopressin (VP)-secreting neurons in the PVN.

Lateral hypothalamic area and paraventricular nucleus connections with subfornical organ neurons: an electrophysiological study in the rat

The neural pathways from the lateral hypothalamic area (LHA) to the hypothalamic paraventricular nucleus (PVN) mediated by subfornical organ (SFO) neurons were examined in urethane-anesthetized male rats in order to determine the excitability of vasopressin (VP)-secreting neurons in the PVN. Microinjection of angiotensin II (AII) into the LHA excited the activity of nearly half (n = 8) of the SFO neurons (n = 18) activated antidromically by electrical stimulation of the PVN. Microinjection of AII into the LHA also caused excitation of approximately one-quarter (n = 11) of putative VP-secreting neurons (n = 45) in the PVN while the excitatory responses of the putative VP-secreting neurons were blocked or attenuated by pretreatment with the AII antagonist, saralasin (Sar), in the SFO. Electrical stimulation of the LHA, on the other hand, produced excitation (n = 17) or inhibition (n = 14) of the putative VP-secreting neurons (n = 52) in the PVN. About half of the excitatory responses to LHA stimulation were blocked or attenuated by pretreatment with Sar in the SFO, whereas the inhibitory responses were not affected. These results show some possible connections between the LHA and PVN, and suggest that AII-sensitive LHA neurons with efferent projections to the SFO may act to enhance the excitability of putative VP-secreting neurons in the PVN via an excitatory influence on the AII-sensitive SFO neurons.

Influence of microinjection of corticosterone into ventromedial hypothalamus on hepatic acetate metabolism in rabbits

Corticosterone was injected into the ventromedial hypothalamus (VMH) of rabbits, and changes in hepatic acetate metabolism were studied. The microinjection of corticosterone with seasame oil into the VMH of intact rabbits increased the rates of 14C transfer from 14C-1-acetate into CO2, glucose, ketone bodies, triglyceride, free cholesterol, free fatty acids and phospholipids but decreased those of 14C transfer into cholesterol ester. However, corticosterone injected into the VMH of rabbits with VMH lesions or the parietal cortex of intact rabbits was without effect on the hepatic acetate metabolism. From these results it might be suggested that the VMH is an integral part of the corticosterone-sensitive brain regulator system in the hepatic acetate metabolism.

Neurons in the lateral hypothalamic area and zona incerta with ascending projections to the subfornical organ area in the rat

Sixteen neurons in the lateral hypothalamic area (LH) and 12 neurons in the zona incerta (ZI) were antidromically activated by electrical stimulation of the subfornical organ (SFO) area in urethane-anesthetized male rats. The activity of these LH and ZI units was examined for response to intracarotid injections of isotonic (0.15 M NaCl solution, 0.05 ml) or hypertonic (0.18 M or 0.3 M NaCl solution, 0.05 ml) saline. All the units did not change their activity to the injections of isotonic saline. Of these units, 9 LH and 5 ZI units displayed an increase and 2 LH and 3 ZI units exhibited a reduction in neuronal activity following the injections of hypertonic saline, while the remaining 5 LH and 3 ZI units were unresponsive. The present results suggest that the LH and ZI neurons with ascending projections to the SFO may carry the information from osmoreceptive elements for modulating the actions of the SFO.