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PubMed1992

Effect of ethanol on the in vivo kinetics of thiamine phosphorylation and dephosphorylation in different organs of rat--II. Acute effects.

The effects of acute ethanol administration on different steps of thiamine (T), thiamine monophosphate (TMP) and pyrosphosphate (TPP) metabolism were determined in vivo in nervous tissues (cerebral cortex, cerebellum, brain stem and sciatic nerve) and in other tissues (small intestinal mucosa, kidney, heart, skeletal muscle and liver) of rats. The radioactivity of T and its phosphoesters in plasma and tissues was determined under steady-state conditions and at fixed time intervals (0.25-24 hr) after an i.p. injection of Thiazole-[2-14C]-thiamine (30 micrograms: 1.25 microCi) in the presence of a constant plasma ethanol concentration (37 mM; 1.75 g.l-1) produced by repeated intragastric administration of ethanol. Control animals received water intragastrically. Ethanol-treated rats and controls were starved, with water ad libitum during the 24 hr study period. Data were evaluated by using appropriate compartmental models, which allowed calculation of fractional rate constants, turnover rates and turnover times. In nervous tissues ethanol enhanced TMP entry (without affecting T entry or T and TMP release), reduced turnover time of total T and TPP, caused an almost general enhancement of TPP dephosphorylation without affecting T pyrophosphorylation, and increased markedly T content in the mixture released by tissues. Overall, ethanol appeared to enhance exchanges of T compounds in nervous tissues. In other tissues, the effects of ethanol were less consistent. Ethanol increased T uptake in kidney and liver and T release in liver and heart, but had no effect on T exchanges in the small intestinal mucosa and in skeletal muscle. In the presence of ethanol, TMP uptake increased in heart and skeletal muscle and decreased in the small intestinal mucosa, while TMP release decreased in heart and remained unchanged in all other organs. Turnover times tended to increase for total T and to decrease for TPP. T pyrophosphorylation was generally reduced, and T phosphates dephosphorylation generally enhanced. T became the most abundant component in the mixture released from all tissues.

Alcohol Drinking↗
PubMed2005

[Effect of tetramethylpyrazine on the responses of respiration and expression of nNOS in brainstem to hypoxia in rats].

The aim of the present study was to investigate the effect of tetramethylpyrazine (TMP) on the changes of respiration and expression of neuronal nitric oxide synthase (nNOS) in brainstem induced by hypoxia in the rats. Hypoxia was induced by inhalation of 8% O2-balanced N2.The electromyogram (EMG) of diaphragm was monitored to evaluate the respiratory response of the rats to hypoxia. The immunohistochemical staining technique was used to study the change of the expression of nNOS in the brainstem during hypoxia. In the rats of hypoxia group, a successive process of response, excitatory followed by inhibitory, was produced. Twenty min after hypoxia, a significant inhibition of respiration occurred, which was characterized with a marked decrease in the inspiratory duration, the respiratory frequency, and the amplitude of inspiration and a prolongation of expiratory duration (P<0.05). In the rats of pretreated with TMP, the respiratory activity was not obviously depressed (P>0.05). In the rats of hypoxia group, the level of nNOS immunoreactivity was enhanced remarkably in the lateral reticular nucleus, nucleus of trapezoid, hypoglossal nucleus and the facial nucleus compared with the control group (P<0.05). In the rats of pretreated with TMP, the nNOS level increased further in the nuclei mentioned above (P<0.05). The results obtained indicate that TMP can reverse the inhibitory effect of hypoxia on respiration in the rats and that nNOS may be involved in the respiratory protective action of TMP.

Animals↗
PubMed1992

[Pharmacokinetics of epidurally administered bupivacaine during prostaglandin E1- or trimetaphan-induced hypotension].

The effects of prostaglandin E1 (PGE1) and trimetaphan (TMP) on the plasma concentrations and derived pharmacokinetic parameters of bupivacaine were studied in 14 women after its epidural administration. Patients, whose ages ranging from 35 to 60 years for mastectomy, received 50 mg of bupivacaine without epinephrine injected into the cervical epidural space during PGE1- or TMP-induced hypotension (80-90 mmHg of the systolic arterial pressure) under general anesthesia with nitrous oxide, oxygen and isoflurane 0.3-0.5%. No significant differences in pharmacokinetic parameters for the absorption and distribution of bupivacaine were found between the two groups. However, the mean elimination half-life of bupivacaine was significantly longer in patients with TMP [5.0 +/- 1.7 (SD) hr] compared with those with PGE1 (3.1 +/- 1.4 hr). The total clearance of bupivacaine was greater in patients with PGE1 (345 +/- 150 ml.min-1) compared with those with TMP (248 +/- 66 ml.min-1). The results of this pharmacokinetic study indicate that the plasma bupivacaine concentration decreases more rapidly during PGE1-induced hypotension than during TMP-induced hypotension.

Adult↗
PubMed1990

Inhibition of vasoconstriction by tetramethylpyrazine: does it act by blocking the voltage-dependent Ca channel?

Using dog mesenteric arterial ring preparations, we studied the in vitro vascular effects of tetramethylpyrazine (TMP, also known as Ligustrazine), a vasoactive component derived from Ligustium Wollichii Franchat; a widely used ingredient in Chinese herbal medicine for the treatment of cardiovascular diseases. TMP had no effect on the resting force of the vascular muscle, but it caused a dose-dependent inhibition of vascular contractile responses to KCl and phenylephrine (PHE). These inhibitory effects of TMP were reversible and more prominent at lower agonist concentrations. TMP also inhibited the responses to PHE in Ca-free medium containing 50 microM EGTA suggesting the action on the release of intracellular Ca2+. Therefore, TMP is not a specific Ca-channel blocker as claimed previously. Its vasodilatory effect is mediated by the inhibition of Ca influx, as well as the release of intracellular Ca2+.

Animals↗
PubMed2006

[The effect of tetramethylpyrazine on the pharmacokinetics of intragastrically administered cyclosporine A in rats].

AIM: To investigate the possible effect of tetramethylpyrazine (TMP), an active ingredient of a commonly used Chinese herb, on the pharmacokinetics of cyclosporine A (CsA) by intragastric administration in rats. METHODS: Forty male Sprague-Dawley rats were equally divided into four groups by randomized block design according to weight. On the first day, after each fasting rat was intragastrically administered CsA (10 mg x kg(-1)), blood samples (0.2 - 0.25 mL) were collected from the tail vein at 0, 1, 2, 3, 4, 6, 8, 12, 24, 36 and 48 h. From day 4 to day 8, each group began to undergo different pretreatments with intragastric administration of water, verapamil (Ver), low and high dose TMP, separately. On day 9, each group intragastrically co-administered CsA (10 mg x kg(-1)) and different pretreatment compounds mentioned above, then blood samples were collected according to the schedule of the first day. The whole blood concentration of CsA was determined by HPLC. Main pharmacokinetic parameters were calculated and compared by statistic analysis. RESULTS: In the group of water pretreated and co-administrated with CsA, no significantly different pharmacokinetic parameters of CsA were found. After Ver pretreatment and co-administration with CsA, AUC(0-48 h) and C(max) were increased significantly (P < 0.01 and P < 0.05); T(1/2) beta and CL were markedly prolonged and decreased (P < 0.05); T(max) and V were not apparently influenced. After low dose TMP pretreatment and co-administration with CsA, there was no significant difference in the pharmacokinetic parameters of CsA, in spite of the increasing trends of AUC(0-48 h) and C(max). After high dose TMP pretreatment and co-administration with CsA, AUC(0-48 h) and C(max) of CsA were increased significantly (P < 0.01), but there was no significant change in other parameters. CONCLUSION: It was indicated that the high dose of TMP could apparently increase the intragastric absorption extent of CsA, while almost had no effect on its elimination process.

Administration, Oral↗
PubMed1991

Oligomeric nature of transmembrane glycoproteins of HIV-2: procedures for their efficient dissociation and preparation of Western blots for diagnosis.

Western blot (WB) analysis of various strains of HIV-2 indicated that transmembrane glycoprotein (TMP) of HIV-2 exists as trimers. These trimers have molecular weights and electrophoretic mobilities in the region of the major external glycoprotein, gp120, resulting in WB misidentification during diagnosis. A simple and rapid procedure was developed using trichloroacetic acid (TCA) to efficiently dissociate oligomeric forms of the TMP to monomers prior to the preparation of WB. This procedure permitted the unambiguous identification of antibodies to gp120 and to the TMP. Use of HIV-2 WB strips without any oligomeric forms of the TMP demonstrated (1) that cross reactivity of HIV-1-positive specimens on HIV-2 WB was mainly directed to Gag and Pol proteins, with some reactivity to gp36/gp41 TMP, but none to gp120; (2) that these strips can substantially reduce the number of specimens falsely identified as dually (HIV-1 and HIV-2) reactive; and (3) that HIV-2-positive specimens reacted to viral gp120 in a strain-specific manner, demonstrating high antigenic variation in this glycoprotein. It is recommended that this general procedure of viral protein dissociation be used for HIV-2 WB preparation.

Blotting, Western↗
PubMed1990

[Blood flow in the operating field during controlled hypotension by nitroglycerin, trimetaphan and prostaglandin E1].

We used the laser flowmeter to measure and compare the effect of nitroglycerin (TNG), trimetaphan (TMP) and prostaglandin E1 (PGE1) on the blood flow of operating field during hypotension induced by each drug. The study was done in 33 patients (TNG:13, TMP:13 and PGE1:7) anesthetized with modified NLA who underwent radical mastectomy. We put the probe of the laser flowmeter on the skin of the opposite breast to the operating field and measured the skin blood flow change. Measurements were made before and during hypotension induced by each drug. TMP-induced hypotension decreased blood flow significantly (P less than 0.05), but TNG and PGE1 had no significant effect. Intraoperative blood losses of TNG and PGE1 group were not significantly larger than that of TMP group. From this study we conclude that TNG, TMP and PGE1 can dry the operating field and decrease intraoperative blood loss similarly. Therefore we should choose the drugs to induce hypotension considering the effect of the drug on blood flow of the important organs and each patient's complications.

Adult↗
PubMedDate not supplied

[Methods of measuring the transmembrane electrical potential in cells].

The methods of intracellular microelectrodes, penetrating ions and potential-sensitive fluorescent probes are considered for their possibility to be used for quantitative estimation of transmembrane electrical potentials (TMP) of small cells (mainly through the example of lymphocytes). The following fluorescent methods are described in detail: separate measurement of two TMP components--potentials on the plasma and mitochondrial membranes of a cell; recording of individual differences of cells according to the TMP value. It is supposed that heterogeneity of cells by the TMP value (in particular, the presence of depolarized cells) may be responsible for errors and divergences of the TMP mean values measured by different methods.

Female↗
PubMed1989

Successful prophylaxis of Pneumocystis carinii pneumonia with trimethoprim-sulfamethoxazole in AIDS patients with previous allergic reactions.

Thirty-four homosexual patients with AIDS were treated for Pneumocystis carinii pneumonia between April 1984 and November 1985. All 31 survivors were treated with oral trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis immediately upon completion of intravenous therapy, despite the prior occurrence of hypersensitivity reactions to intravenous TMP-SMX in 21 of these patients. Only four patients had subsequent reactions to oral TMP-SMX requiring the drug's discontinuation. None of the patients remaining on prophylaxis developed recurrent Pneumocystis pneumonia. Oral TMP-SMX appears effective at preventing recurrent Pneumocystis pneumonia in patients with AIDS. Hypersensitivity reactions during therapy with TMP-SMX may not be a contraindication to continuation of therapy and subsequent oral prophylaxis.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Radiolysis of spin-labeled DNA: an electron spin resonance investigation.

The reactions of free and DNA-bound 2,2,5,5-tetramethylpyrrolidine-N-oxyl (PROXYL) probes with radicals generated during radiolysis of dilute aqueous solutions of DNA were examined. For the free PROXYL probe in deaerated solution with each of the four nucleotides (dAMP, dCMP, dGMP, and TMP) it was found that the pyrimidine radicals were more reactive toward the probe than were the purine radicals. Reactions of the electron adduct of TMP and the hydroxyl radical adducts of dAMP, dGMP, and TMP with the probe resulted in little or no reduction of the probe. For TMP these results are consistent with the fact that both the protonated electron and hydroxyl radical adducts of TMP will covalently bind to the nitroxide function of the probe. Reduction of the PROXYL probe was observed in reactions with the hydroxyl radical adduct of dCMP and with the electron adducts of dAMP, dCMP, and dGMP. Results of the radiolysis of the free PROXYL probe in deaerated dilute solution of DNA suggest that the PROXYL probe protects the DNA from water radical attack as the ratio of DNA bases to PROXYL probe increases above 50:1. Reactions of DNA-bound probes are dependent on the depth of the nitroxide function in relation to the major groove of the DNA helix. Two probes with tether lengths which are less than the depth of the major groove show an expected increase in reactions with DNA base radicals as compared to a probe with a tether that extends beyond the groove. The longer probe is involved largely in reactions with sugar and water radicals along the periphery of the DNA helix. In the presence of oxygen, there is a dramatic decrease in the loss of both the free and DNA-bound probes due to the lack of reaction of these probes with peroxyl radicals formed by the addition of molecular oxygen to DNA radicals.

Cyclic N-Oxides↗
PubMed1987

[Effect of thyroxine in vitro on the transmembrane potential of rat liver mitochondria].

It has been shown in in vitro experiments that a certain latent period after the addition of thyroxine (T4) and triiodothyronine (T3) was necessary for the manifestation of their effects on transmembrane potential (TMP) of the rat liver mitochondria. The duration of the lag-period decreased upon an increase in the concentrations of these hormones, and T4 at a dose of 2.10(-4) M produced a fall in TMP immediately after its addition. The rate of TMP fall was in proportion with the concentrations of thyroid hormones introduced into the cell, with T3 30-40% more effective than T4. It was established that the action of I2 resembled that of thyroid hormones, namely, a fall in TMP, mitochondrial swelling, activation of transhydrogenase Kl was ineffective. It is suggested that the appearance of the lag-period upon the action of thyroid hormones might be explained by the period of time necessary for the formation of the active iodine forms, as well as by the formation of fatty acids (donators of H+) by mitochondrial phospholipases. All these factors lead to TMP fall resulting in decreased formation of sufficient ATP quantities in mitochondria.

Animals↗
PubMed1987

Site-specific renal cytotoxicity and cell proliferation in male rats exposed to petroleum hydrocarbons.

The pathologic significance of intracytoplasmic protein droplet accumulation within renal tubular epithelial cells induced experimentally in male rats after exposure to various environmental chemicals, such as unleaded gasoline (UG), is poorly understood. 2,2,4-Trimethylpentane (TMP), a component of UG, also is a potent inducer of protein droplets in male rats. This study documents a strong correlation between protein droplet accumulation, single cell necrosis, and regeneration of the male F344 rat nephron during a 3-week exposure regimen to a wide dose range of inhaled UG or gavaged TMP covering several orders of magnitude (2 to 2000 ppm of UG and 0.2 to 50 mg/kg of TMP, respectively). Autoradiographic analyses of various segments of the nephron were conducted after continuous administration of [methyl-3H]thymidine via osmotic pumps implanted during the last week of UG or TMP exposure. The P2 segment of the proximal tubule of control rats from both experiments had a higher rate of cell turnover (approximately 11%) than the adjacent P1 (approximately 2%) or P3 segments (approximately 3%). The P2 segment of rats exposed to UG or TMP responded with additional dose-related (up to 6-fold) increases in cell turnover. The extent and localization of cell proliferation closely paralleled the extent and severity of accumulation of crystalloid protein droplets and single cell necrosis. Biochemical and immunohistochemical studies have shown that protein droplets in male, but not female rats, consist primarily of alpha-2u-globulin, a low molecular weight protein synthesized by the liver under androgenic control. Increased cell turnover in the P2 segment of male rats may be related to altered catabolism of alpha-2u-globulin. This accelerated cell proliferation may be an essential factor in the development of renal cancer in male rats exposed to UG or other volatile hydrocarbons.

Animals↗
PubMed1985

Dihydrofolate reductase. The stereochemistry of inhibitor selectivity.

X-ray structural results are reported for 10 triazine and pyrimidine inhibitors of dihydrofolate reductase, each one studied as a ternary complex with NADPH and chicken dihydrofolate reductase. Analysis of these data and comparison with structural results from the preceding paper (Matthews, D.A., Bolin, J.T., Burridge, J.M., Filman, D.J., Volz, K.W., Kaufman, B. T., Beddell, C.R., Champness, J.N., Stammers, D.K., and Kraut, J. (1985) J. Biol. Chem. 260, 381-391) in which we contrasted binding of the antibiotic trimethoprim (TMP) to chicken dihydrofolate reductase on the one hand with its binding to Escherichia coli dihydrofolate reductase on the other, permit identification of differences that are important in accounting for TMP's selectivity. The crystallographic evidence strongly suggests that loss of a potential hydrogen bond between the 4-amino group of TMP and the backbone carbonyl of Val-115 when TMP binds to chicken dihydrofolate reductase but not when it binds to the E. coli reductase is the major factor responsible for this drug's more potent inhibition of bacterial dihydrofolate reductase. A key finding of the current study which is important in understanding why TMP binds differently to chicken and E. coli dihydrofolate reductases is that residues on opposite sides of the active-site cleft in chicken dihydrofolate reductase are about 1.5-2.0 A further apart than are structurally equivalent residues in the E. coli enzyme.

Animals↗
PubMed1983

Trimethoprim-sulfadiazine in the horse: serum, synovial, peritoneal, and urine concentrations after single-dose intravenous administration.

Six healthy adult mares were given a single IV injection of trimethoprim (TMP)-sulfadiazine (SDZ) at a dosage rate of 2.5 mg of TMP/kg of body weight and 12.5 mg of SDZ/kg. Serum, synovial, peritoneal, and urine TMP-SDZ concentrations were measured serially over a 48-hour period. The highest measured mean concentrations of TMP and SDZ were found in the first (0.5 hour) sample of serum, synovial fluid, and peritoneal fluid. The mean peak concentrations of TMP and SDZ averaged 4.37 micrograms/ml and 21.81 micrograms/ml for serum, 2.95 micrograms/ml and 15.31 micrograms/ml for synovial fluid, and 3.88 micrograms/ml and 19.52 micrograms/ml for peritoneal fluid, respectively. Urine concentrations of the drugs were relatively high and peaked early. The elimination rate for TMP and SDZ averaged 0.41 and 0.26 hour-1, while the elimination half-life was 1.91 and 2.71 hours, respectively, and the volume of distribution averaged 0.59 and 0.52 L/kg, respectively.

Animals↗
PubMed1982

[Lung tissue diffusion of intravenous trimethoprim-sulfamethoxazole combination (author's transl)].

In 13 cases of pneumonectomy, we have studied the concentration of TMP-SMZ in tissue and serum, after three days of treatment. Four hours after TMP-SMZ injection, the tissue's samples obtained from crushed and mixed ; the dosages were performed by a microbiological assay. As we previously described in bronchial secretions : the lung penetration of TMP is important ; the tissue concentrations were higher than in serum ; the diffusion of SMZ is low. The ratio of TMP to SMZ were diffusion of SMZ is low. The ratio of TMP to SMZ were different in serum and tissue, but the antibacterial activity is not affected in vitro by the value's modification.

Adult↗
PubMed1982

[Bone diffusion of trimethoprim and sulfamethoxazole high pressure liquid chromatography (HPLC) (author's transl)].

Fourteen patients about to undergo total hip prosthesis were given 640 mg TMP and 3.2 g SMZ during the 48 hours previous to surgical procedure. Ten ml blood, fragments of cortical bone, spongy bone and bone marrow were taken 1 h to 1 h 30 mn after the last drug intake. Dosage were made using HPLC after biological specimens had been treated on a TM C18 Set Pack column for deproteinization and isolation of the active substances. Results show high mean serum levels, 7.73 micrograms/ml for TMP and 143.82 micrograms/ml for SMZ. Whatever the bone specimen be, diffusion of TMP was excellent, with levels between 2.20 and 4.96 microgram/g whereas SMZ levels were between 13.85 and 23.85 microgram/g. For each sample, the TMP/SMZ ratio was the following : in serum it was equal to 0.055, which is in accordance with results already published ; the ratio between the levels of the two active substances was more favourable for cortical bone (ratio = 0.185) than for spongy bone (ratio = 0.286) or bone marrow (ratio = 0.324). The bone level/serum level ratio shows a diffusion which is two to six times greater for TMP than for SMZ in all bone specimens : TMP penetrates marrow better than it does cortical and spongy tissues ; diffusion is practically equivalent in the two latter tissues ; SMZ concentrates very strongly in the marrow and not so well in the cortical and the spongy bones.

Aged↗
PubMed1995

[Effects of nitroglycerin, prostaglandin E1, trimetaphan and nicardipine on systemic vascular resistance, pulmonary vascular resistance and pulmonary-systemic vascular resistance ratio in dogs].

Effects of the experimentally induced hypotension with 4 vasodilators; nitroglycerin (TNG), prostaglandin E1 (PGE1), trimetaphan (TMP) and nicardipine (NCP) on systemic vascular resistance (SVR), pulmonary vascular resistance (PVR) and pulmonary-systemic vascular resistance ratio (PVR/SVR ratio) were studied in dogs. The SVR values were significantly reduced by TNG, PGE1 and NCP, and not affected by TMP. The PVR values were significantly reduced by TNG and PGE1, and not affected by TMP and NCP. The PVR/SVR ratio values were significantly reduced by TNG, and significantly increased by NCP, and not affected by PGE1 and TMP. We concluded that TNG reduced PVR and SVR but it affected PVR more; PGE1 reduced PVR and SVR equivalently; TMP did not affect PVR and SVR remarkably; NCP reduced SVR but did not affect PVR.

Alprostadil↗
PubMed1995

[Effect of tetramethylhyrazine on proliferation of human fetal mesangial cells].

Tetramethylhyrazine (TMP) 0.6 and 1.2 mmol were added to human fetal mesangial cell (MC) cultures for 6 days, and the amounts of MC (cells/ml) were 37580 +/- 3475 and 27350 +/- 3418 respectively, significantly lower than that 71850 +/- 5108 in control (P < 0.05). The 3H-TdR incorporation by the MC with corresponding TMP were 1017 +/- 201 and 583 +/- 271, also significantly lower, than that 3575 +/- 306 in control (P < 0.01). After adding the TMP (1 mmol) to the cultures, the IL-6 bioactivity were 2118 +/- 215 that were markedly lower than those in controls (4128 +/- 351, P < 0.01). It revealed that the TMP inhibited the growth of MC and the mechanism of its inhibition might be due to that TMP could reduce the IL-6.

Cell Division↗