176
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Fatherazi S, Lai H, Kazi S, Horita A. Intraseptal morphine potentiates pentobarbital narcosis and hypothermia in the rat. Pharmacol Biochem Behav 1985; 23:505-7. [PMID: 4070326 DOI: 10.1016/0091-3057(85)90409-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Morphine injected intraseptally in the amounts of 35 and 70 nmol prolonged pentobarbital-induced narcosis in the rat. Pentobarbital-induced hypothermia was also potentiated by intraseptal injection of 70 nmol of morphine. These effects were antagonized when morphine was injected together with naltrexone (29 nmol). Naltrexone injected by itself into the septum did not significantly affect pentobarbital-narcosis and hypothermia. It is concluded that activation of mu opioid receptors in the septal region could affect the actions of pentobarbital.
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177
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Pae YS, Lai H, Horita A. Hyperthermia in the rat from handling stress blocked by naltrexone injected into the preoptic-anterior hypothalamus. Pharmacol Biochem Behav 1985; 22:337-9. [PMID: 4039067 DOI: 10.1016/0091-3057(85)90400-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Experimental handling and colonic temperature measurement have been shown to cause stress and induce a long-lasting rise in colonic temperature in the rat. This stress-induced hyperthermia was blocked by microinjection of the narcotic antagonist naltrexone into the preoptic-anterior hypothalamus (POAH) of the brain, but was not significantly affected by similar injections into areas of the brain above the POAH. Thus, the stress-induced hyperthermia may be caused by activation of the endogenous opioid mechanism in the POAH.
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178
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Chou CK, Guy AW, McDougall JA, Lai H. Specific absorption rate in rats exposed to 2,450-MHz microwaves under seven exposure conditions. Bioelectromagnetics 1985; 6:73-88. [PMID: 3977970 DOI: 10.1002/bem.2250060108] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Both positive and negative biological effects of microwaves on drug actions in rats exposed to 1-mW/cm2, 2,450-MHz microwaves have been reported by several investigators. We conducted dosimetry studies for seven different exposure conditions to determine whether these different results could be due to the rats having been exposed differently. They included anterior and posterior exposures in a circular waveguide, near field, far field with E- or H-field parallel to the long axis of the body and dorsal exposure in a miniature anechoic chamber with E- or H-field parallel to the long axis of the body. The average specific absorption rates (SARs) in the head, tail, and body of the exposed rats were measured by means of a calorimetry system. The local SARs at eight locations in the brain were determined by temperature measurement with Vitek probes. Intensive coupling of energy to the tail when it was exposed parallel to the E-field was shown by thermography. For the same average incident power density, the average SARs in the heads of rats were about two times higher in the circular waveguide than for other exposures. The local SARs in the brain varied for different exposure conditions. Statistical comparisons of SARs under the different exposure conditions are presented.
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179
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Pae YS, Lai H, Horita A. Effects of treatments with apomorphine, haloperidol and ethanol on apomorphine-induced changes in body temperature in the rat. Neuropharmacology 1984; 23:1109-12. [PMID: 6514146 DOI: 10.1016/0028-3908(84)90137-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In previous research, we discovered two DA-related thermoregulatory mechanisms in the rat: a haloperidol-sensitive, hypothermia-inducing mechanism and a haloperidol-nonsensitive, hyperthermia-inducing mechanism. The latter mechanism must also involve serotonin, since its activity can be blocked by serotonin antagonists. We have now found that the responsiveness of these mechanisms to apomorphine could be selectively affected by acute pretreatments with apomorphine, haloperidol and ethanol. The hypothermia-inducing mechanism was supersensitized by pretreatment with either haloperidol (0.25 mg/kg, administered 5 days earlier) or ethanol (3 g/kg, 15 h), but was not affected by pretreatment with apomorphine (1 mg/kg, 15h). In contrast, the hyperthermia-inducing mechanism was supersensitized and desensitized by similar pretreatments with apomorphine and ethanol, respectively, but was not affected by pretreatment with haloperidol.
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180
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Yamawaki S, Lai H, Horita A. Effects of dopaminergic and serotonergic drugs on ethanol-induced hypothermia. Life Sci 1984; 34:467-74. [PMID: 6229679 DOI: 10.1016/0024-3205(84)90502-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The effects of dopaminergic and serotonergic drugs on ethanol-induced hypothermia were studied in the rat. Pretreatment with haloperidol attenuated the hypothermia in a dose-dependent manner. Apomorphine produced a dose-dependent effect on the hypothermia. At a dose of 2.0 mg/kg, apomorphine potentiated ethanol-induced hypothermia, whereas at 0.1 mg/kg, it produced a delayed attenuation effect between 30 min and 45 min after its injection. The former effect was blocked by haloperidol, whereas the latter was not affected by haloperidol, but blocked by pretreatment with parachlorophenylalanine. It is concluded that both dopamine and serotonin exert modulatory effects on ethanol-induced hypothermia.
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181
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Lai H, Horita A, Chou CK, Guy AW. Effects of acute low-level microwaves on pentobarbital-induced hypothermia depend on exposure orientation. Bioelectromagnetics 1984; 5:203-11. [PMID: 6732876 DOI: 10.1002/bem.2250050208] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Two series of experiments were performed to study the effects of acute exposure (45 min) to 2,450-MHz circularly polarized, pulsed microwaves [1 mW/cm2, 2-mus pulses, 500 pps, specific absorption rate (SAR) 0.6 W/kg] on the actions of pentobarbital in the rat. In the first experiment, rats were irradiated with microwaves and then immediately injected with pentobarbital. Microwave exposure did not significantly affect the extent of the pentobarbital-induced fall in colonic temperature. However, the rate of recovery from the hypothermia was significantly slower in the microwave-irradiated rats and they also took a significantly longer time to regain their righting reflex. In a second experiment, rats were first anesthetized with pentobarbital and then exposed to microwaves with their heads either pointing toward the source of microwaves (anterior exposure) or pointing away (posterior exposure). Microwave radiation significantly retarded the pentobarbital-induced fall in colonic temperature regardless of the orientation of exposure. However, the recovery from hypothermia was significantly faster in posterior-exposed animals compared to those of the anterior-exposed and sham-irradiated animals. Furthermore, the posterior-exposed rats took a significantly shorter time to regain their righting reflex than both the anterior-exposed and sham-irradiated animals.
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182
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Lai H, Horita A. Apomorphine-induced hypothermia affected by acute treatment with apomorphine, haloperidol, or ethanol. Psychopharmacology (Berl) 1984; 82:335-7. [PMID: 6427825 DOI: 10.1007/bf00427681] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Apomorphine-induced hypothermia was studied in rats pretreated with a dose of apomorphine (mg/kg, IP), haloperidol (0.25 mg/kg, IP), ethanol (3 g/kg, PO), or apomorphine + ethanol. Pretreatment with apomorphine attenuated the hypothermic response, pretreatment with either haloperidol or ethanol potentiated it, and pretreatment with apomorphine together with ethanol did not alter it. These data show that an acute treatment with a dopaminergic drug can alter the responsiveness of the dopaminergic thermoregulatory system, and also that ethanol has an inhibitory effect on the dopamine mechanism.
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183
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Lai H, Horita A, Chou CK, Guy AW. Ethanol-induced hypothermia and ethanol consumption in the rat are affected by low-level microwave irradiation. Bioelectromagnetics 1984; 5:213-20. [PMID: 6732877 DOI: 10.1002/bem.2250050209] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Microwave irradiation of rats by circularly polarized, 2,450-MHz, pulsed waves (2-microseconds pulses; 500 pps) was performed in waveguides to determine effects on ethanol-induced hypothermia and on ethanol consumption. Rats injected intraperitoneally with ethanol (3 g/kg in a 25% v/v water solution) immediately after 45 min of microwave irradiation exhibited attenuation of the initial rate of fall in body temperature, which was elicited by the ethanol, but exhibited no significant difference in maximal hypothermia as compared with that of sham-irradiated rats. Microwave irradiation did not affect the consumption of a 10% sucrose (w/v) solution by water-deprived rats. However, it enhanced the consumption of a solution of 10% sucrose (w/v) + 15% ethanol (v/v) by water-deprived animals. These results were obtained at a specific absorption rate (SAR) of 0.6 W/kg, which rate of energy dosing would require a power density of 3-6 mW/cm2 if exposure of the animals had occurred to a 12-cm plane wave.
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184
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Yamawaki S, Lai H, Horita A. Dopaminergic and serotonergic mechanisms of thermoregulation: mediation of thermal effects of apomorphine and dopamine. J Pharmacol Exp Ther 1983; 227:383-8. [PMID: 6631720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The effects of dopaminergic and serotonergic antagonists on apomorphine- and dopamine-induced changes in body temperature were studied in the rat. Intraperitoneal administration of apomorphine produced dose-dependent hypothermia. At a dose of 0.1 mg/kg, apomorphine caused either no significant effect or a slight decrease in body temperature. However, it caused hyperthermia in rats pretreated with the DA antagonist, haloperidol, and hypothermia in rats pretreated with the serotonin depletor, p-chlorophenylalanine or serotonin antagonists, cyproheptadine, metergoline or cinanserin. Intracerebroventricular injection of 100 micrograms/2 microliter of DA transiently decreased body temperature. Pretreatment with cyproheptadine potentiated and prolonged the responses. However, the same injection of DA produced hyperthermia in haloperidol-pretreated animals. These data suggest that both dopaminergic and serotonergic mechanisms in the brain mediate the effects of apomorphine on body temperature. We propose that apomorphine can simultaneously activate two opposing DA-related thermoregulatory mechanisms with different sensitivities to haloperidol: a haloperidol-sensitive hypothermia and a haloperidol-nonsensitive hyperthermia mechanisms. Furthermore, the action of the latter mechanism is mediated by a secondary activation of serotonergic mechanisms.
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185
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Lai H, Horita A, Chou CK, Guy AW. Psychoactive-drug response is affected by acute low-level microwave irradiation. Bioelectromagnetics 1983; 4:205-14. [PMID: 6626272 DOI: 10.1002/bem.2250040303] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The effects of various psychoactive drugs were studied in rats exposed for 45 min in a circularly polarized, pulsed microwave field (2450 MHz; SAR 0.6 W/kg; 2-microseconds pulses, 500 pps). Apomorphine-induced hypothermia and stereotypy were enhanced by irradiation. Amphetamine-induced hyperthermia was attenuated while stereotypy was unaffected. Morphine-induced catalepsy and lethality were enhanced by irradiation at certain dosages of the drug. Since these drugs have different modes of action on central neural mechanisms and the effects of microwaves depend on the particular drug studied, these results show the complex nature of the effect of microwave irradiation on brain functions.
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186
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Lai H, Kazi MS, Carino MA, Horita A. Chronic haloperidol treatment potentiates apomorphine- and ethanol-induced hypothermia in the rat. Life Sci 1982; 30:821-6. [PMID: 7200179 DOI: 10.1016/0024-3205(82)90595-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Supersensitivity developed in the central dopaminergic system of the rat after 21 days of chronic haloperidol injection. This was indicated by a higher level of apomorphine-elicited stereotypic behavior and by higher concentrations of striatal 3H-spiroperidol binding sites in haloperidol-treated rats compared to saline-treated controls. The chronic haloperidol treatment did not affect the baseline body temperature but potentiated both apomorphine- and ethanol-induced falls in core temperature. Such potentiation may also be related to dopamine supersensitivity. However, no significant correlation was found between apomorphine- or ethanol-induced hypothermia and apomorphine-elicited stereotypic behavior or the concentration of striatal 3H-spiroperidol binding sites. Hence, the nigrostriatal dopamine system does not appear to be involved in the development of hypothermic responses to these agents.
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187
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Lai H, Carino MA, Sperry R, Horita A. Effects of microinjection of 2-chloro-11 (2-dimethylaminoethoxy)-dibenzo[b,f]-thiepine (zotepine), thioridazine and haloperidol into the striatum and nucleus accumbens on stereotypic behaviour and motor activity. J Pharm Pharmacol 1981; 33:252-4. [PMID: 6115914 DOI: 10.1111/j.2042-7158.1981.tb13772.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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188
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Lai H, Carino MA, Horita A. Chronic treatments with zotepine, thioridazine, and haloperidol affect apomorphine-elicited stereotypic behavior and striatal 3H-spiroperidol binding sites in the rat. Psychopharmacology (Berl) 1981; 75:388-90. [PMID: 6122233 DOI: 10.1007/bf00435859] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Apomorphine (AP)-elicited sterotypic behavior and striatal 3H-spiroperidol binding sites were studied in rats given 3 weeks of chronic treatment with one of the following neuroleptic drugs: zotepine (10 or 20 mg/kg/day IP); thioridazine (10 or 20 mg/kg/day IP); haloperidol (2 or 5 mg/kg/day IP). On days 10-12 after the chronic neuroleptic treatment, enhancement of AP-elicited stereotypy was seen in the high- and low-dose haloperidol-treated, as well as in the high-dose thioridazine and zotepine-treated rats when compared to that of saline-injected controls. No significant change in the response to AP was found in the low-dose thioridazine and zotepine-treated animals. Significant increases in the concentration of striatal 3H-spiroperidol binding sites were seen after treatment with all three neuroleptics, both high and low doses. A positive correlation was found between AP-elicited stereotypy and the concentration of striatal 3H-spiroperidol binding sites in the haloperidol-treated and control rats. However, no such correlation was seen after chronic thioridazine and zotepine treatments.
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189
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Lai H, Carino MA, Sperry R, Horita A. Effects of thioridazine on apomorphine-elicited stereotypic behavior and motor activity. Pharmacol Biochem Behav 1980; 13:397-401. [PMID: 7191570 DOI: 10.1016/0091-3057(80)90245-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Bilaterally injected thioridazine (10 micrograms) into the striata of rats augmented the stereotypic behavior elicited by apomorphine. The enhancing effect was attenuated by pretreatment with alpha-methyl-p-tyrosine. At 48 hr postinjection of thioridazine (1.0 mg/kg, IP), motor suppression from a low dose of apomorphine (0.2 mg/kg, IP) was enhanced; however, motor response to a high dose of apomorphine (1 mg/kg, SC) was not affected. Possible mechanisms of action of thioridazine are discussed.
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190
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191
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Lai H, Makous WL, Horita A, Leung H. Effects of ethanol on turnover and function of striatal dopamine. Psychopharmacology (Berl) 1979; 61:1-9. [PMID: 108711 DOI: 10.1007/bf00426801] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Acute oral administration of ethanol increased the rate of depletion of dopamine in the striata of rats injected with alpha-methyl-p-tyrosine. This effect was eliminated by pretreatment with atropine or by lesioning of the striato-nigral tract. Ethanol also attenuated the inhibitory effect of apomorphine on turnover of striatal dopamine. Unilateral injection of ethanol into the neostriatum of rats followed by intraperitoneal injection of either apomorphine or amphetamine elicited marked ipsilateral head-to-tail body turning. This turning was blocked by pretreatment with haloperidol. Chronic intubation of ethanol to rats enhanced contralateral body turning elicited by unilateral intrastriatal injection of dopamine. Injection of 6-hydroxydopamine into the substantia nigra led to denervation supersensitivity of dopaminergic functions in the neostriatum. This effect was not seen in rats that were given ethanol postinjection of 6-hydroxydopamine. These results suggested that ethanol has an inhibitory effect on the nigrostriatal dopaminergic system.
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192
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Lai H, Makous WL, Quock RM, Horita A. Visual deprivation affects serotonin levels in the visual system. J Neurochem 1978; 30:1187-9. [PMID: 660196 DOI: 10.1111/j.1471-4159.1978.tb12416.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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193
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Lai H, Quock RM, Makous W, Horita A, Jen LS. Methylazoxymethanol acetate: effect of postnatal injection on brain amines and behavior. Pharmacol Biochem Behav 1978; 8:251-7. [PMID: 652833 DOI: 10.1016/0091-3057(78)90312-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The antimitotic drug, methylazoxymethanol acetate (MAMA), was injected into newborn rats during the first four days of life. At 48 days of age, these rats weighed one-third less than controls, as did the cerebella of their brains, but the rest of their brains weighed only 7% less than those of controls. The cerebella structures of the drug-injected rats was highly disorganized. Purkinje cells were scattered haphazardly in the granular layer instead of forming a monolayer. More foldings and short folia were found in the cerebella of drugged animals. In spite of these large morphological differences, the total amounts of norepinephrine and serotonin in the cerebella of the drugged rats were not different from those of the control rats. Behavioral effects of postnatal injection of MAMA include retarded development of the righting reflex,i.e., the drugged pups took longer time to right themselves when placed on their backs during the first nine days after birth; and scondly, MAMA reduced locomotor activity measured 45 days after birth.
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194
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Horita A, Carino MA, Lai H. Influence of catecholamine antagonists and depletors on the CNS effects of TRH in rabbits. PROGRESS IN NEURO-PSYCHOPHARMACOLOGY 1977; 1:107-13. [PMID: 103108 DOI: 10.1016/0364-7722(77)90032-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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195
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Sweeney G, Freeman KB, Rothwell D, Lai H. Decrease in hepatic cytochrome P-450 and catalase following allylisopropyl acetamide: the effect of concomitant hemin administration. Biochem Biophys Res Commun 1972; 47:1366-71. [PMID: 5051307 DOI: 10.1016/0006-291x(72)90223-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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196
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Sweeney GD, Janigan D, Mayman D, Lai H. Experimental porphyria. I. The experimental porphyrias--a group of distinctive metabolic lesions. S Afr Med J 1971:68-72. [PMID: 4113777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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