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PubMed1989

[Antidiarrheal agents: tools and therapeutic agents].

A host of chemically diverse compounds have antidiarrheal potency, however, only a fraction of these agents has gained clinical acceptance. But regardless of their therapeutic status, the effects of these drugs have enhanced our understanding of the physiology and pathophysiology of the intestinal mucosa. Fluid- and electrolyte substitution are the primary therapeutic measures in severe diarrhea, for that purpose oral rehydration using glucose-sodium solutions has proven simple and effective. In addition gut-selective opiates, for instance loperamide, are indicated. Opiates not only decrease propulsive motor activity of the bowel but also increase intestinal water and electrolyte absorption, both effects are neuronally mediated. Antimicrobial drugs are necessary in only a small fraction of patients with diarrhea. Experimental findings have indicated possible future candidates for treatment of diarrhea: Besides opiates and glucose-electrolyte solutions water and electrolyte absorption is enhanced by alpha 2-adrenergic agents, corticosteroids, and somatostatin. Inhibitors of electrolyte secretion include phenothiazines and opiates, possibly because of binding to calcium-calmodulin, calcium-channel blockers, membrane-stabilizing agents for instance propranolol and inhibitors of prostaglandin-synthesis such as non-steroidal antirheumatic agents.

Antidiarrheals↗

PubMed1985

Magnesium sulfate and beta-mimetic dual-agent tocolysis in preterm labor after single-agent failure.

Twenty-three patients in preterm labor failed to respond to single-agent tocolytic therapy or could not tolerate the dosage necessary to inhibit contractions. A combination of magnesium sulfate and ritodrine or terbutaline was used to inhibit labor in these patients. Fourteen patients (60.9%) responded to dual-agent tocolysis by delaying delivery for 48 hours or more. Six patients had delivery delayed for more than one week. Five patients had multiple gestations; three of them had delivery delayed more than 48 hours. Five patients developed pulmonary edema under treatment with dual-agent tocolysis; all responded to diuretic and/or oxygen therapy after the termination of tocolysis. Dual-agent tocolysis may significantly prolong some pregnancies complicated by preterm labor, but only at some risk to maternal well-being.

Adrenergic beta-Agonists↗

PubMed1979

Exposure to chemicals, physical agents, and biologic agents in mycosis fungoides and the Sézary syndrome.

The history of occupational, environmental, and/or iatrogenic exposure to potential carcinogenic agents was obtained at the time of onset of skin disease in 43 of 44 patients with cutaneous T-cell lymphoma (mycosis fungoides and the Sézary syndrome) entering a National Cancer Institute therapeutic trial. A history of multiple exposures to these agents was common, the two most frequent being chemicals (91% of patients) and drugs (86%). Mean duration of expsosure was 13 years for chemicals and 18 years for drugs. The most common chemicals were air pollutants (39%), pesticides (36%), solvents and vapors (30%), and detergents and disinfectants (14%). Increased severity of disease was seen with increaed duration of chemical exposure in stage V cutaneous T-cell lymphomas only. The most frequent drugs besides tobacco (86%) were analgesics (20%), tranquilizers (18%), and thiazides (14%). Second cancers occurred in four patients, including two renal cell carcinomas, and a family history of cancer was present in 11. Fourteen of 22 patients questioned had recurrent herpes simplex. Patients with chronic skin disease who have long-term exposure to combinations of chemicals, physical agents, and biologic agents, are heavy smokers, or have recurrent herpes simplex appear to be prime candidates for developing mycosis fungoides or the Sézary syndrome.

Adult↗

PubMed1993

A thrombosis model for evaluating thrombolytic agents in the guinea-pig: comparison of t-PA, scu-PA and a novel thrombolytic agent, staphylokinase, on thrombolytic activity.

We have studied three fibrin-specific thrombolytic agents in a photochemically-induced, guinea-pig femoral artery model of thrombosis. Tissue-type plasminogen activator (t-PA, 0.3 and 1 mg/kg), single-chain urokinase-type plasminogen activator (scu-PA,5 and 15 mg/kg) and a novel thrombolytic agent, staphylokinase (SAK, 0.3 and 1 mg/kg) were intravenously infused for 30 min after arterial occlusion by a photochemically-induced reaction between rose bengal and light (540 nm). These thrombolytic agents induced thrombolysis in 17-66% of animals and 24 h later, reocclusion occurred in 75-100%. t-PA hardly altered plasma fibrinogen throughout the experimental period. In contrast, scu-PA (15 mg/kg) decreased plasma fibrinogen and alpha 2-antiplasmin levels by 25% and 90% respectively 90 min after beginning the infusion. SAK markedly decreased plasma fibrinogen and alpha 2-antiplasmin levels in dose- and time-dependent manners. These results suggest that this model of thrombosis has a relatively high sensitivity to t-PA, which induced thrombolysis without decreasing fibrinogen and alpha 2-antiplasmin, compared with the other two fibrin-specific thrombolytic agents.

Animals↗

PubMed2006

Monascus fermentation of dioscorea for increasing the production of cholesterol-lowering agent--monacolin K and antiinflammation agent--monascin.

Monacolin K, an inhibitor for cholesterol synthesis, is the secondary metabolite of Monascus species. The formation of the secondary metabolites of the Monascus species is affected by cultivation environment and method. This research uses sweet potato (Ipomoea batatas), potato (Solanum tuberosum), casava (Manihot esculenta), and dioscorea (Dioscorea batatas) as the substrates and discusses the best substrate to produce monacolin K. The results show that Monascus purpureus NTU 301, with dioscorea as the substrate, can produce monacolin K at 2,584 mg kg(-1), which is 5.37 times to that resulted when rice is used as the substrate. In addition, more amount of yellow pigment can be found in Monascus-fermented dioscorea than in Monascus-fermented rice. The certain composition of yellow pigment is identified as monascin, which has been shown as an antiinflammation agent exhibiting potent inhibitory effects on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation in mice in previous studies. Therefore, dioscorea is concluded to be the best substrate for Monascus species to produce the cholesterol-lowering agent-monacolin K and antiinflammation agent-monascin.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1991

[Clinical pharmacology of anticancer agents. (Part 1) Introduction, alkylating agents and platinum compounds].

Pharmacokinetic concepts as to absorption, distribution, metabolism and excretion of anticancer agents, and how drugs reach to the site of action were reviewed. Then, roles of the liver and kidney to the excretion and metabolism, intracellular pharmacokinetics, and relationships between drug response and cell proliferation kinetics or cell cycle phase were explained. Drug development, mode of action and pharmacokinetics of alkylating agents and platinum compounds were reviewed. This includes: alkylating agents: nitrogen mustard, phenylalanine mustard, estracyte, cyclophosphamide, carboquone, busulfan, nitrosourea, etc., and platinum compounds: cisplatin, carboplatin, 254-S, DWA-2114 R, NK-121.

Alkylating Agents↗

PubMed1978

[Inhibition and psychotropic agents. Therapeutic disinhibitory agents].

The concept of disinhibitory agent is heterogeneous. If the disinhibitory property refers to inhibition in its clinical meaning, all psychotropic drugs can answer the denomination of disinhibitory agent when they are prescribed in some pathological entities. Traditionally this denomination refers to a few major tranquillizers, the antipsychotic action of which is linked to the improvement of the affective indifference and of the decrease of the psychomotor activity. However the pharmacokinetic data reveal that some potent sedative neuroleptics can become disinhibitors at high doses and some disinhibitory agents can become sedative substances at higher doses.

Antidepressive Agents↗

PubMed1993

Indomethacin/ibuprofen-like anti-inflammatory agents selectively potentiate the gamma-aminobutyric acid-antagonistic effects of several norfloxacin-like quinolone antibacterial agents on [35S]t-butylbicyclophosphorothionate binding.

Four piperazinoquinolone antibacterial drugs (norfloxacin, ciprofloxacin, enoxacin, and pipemidic acid), known to be gamma-aminobutyric acid (GABA) antagonists, fully reversed the inhibitory effect of GABA on [35S]t-butylbicyclophosphorothionate ([35S] TBPS) binding to rat brain membranes in vitro. Twelve indomethacin/ibuprofen-like arylalkanoic acid (AAA) anti-inflammatory drugs alone had no effect on [35S]TBPS binding, or on its inhibition by GABA, but potentiated the GABA-antagonistic effects of the four quinolones. Felbinac (4-biphenylacetic acid) was most potent in this respect (EC50 = 110 nM, together with 5 microM norfloxacin), followed by flurbiprofen > anirolac > metiazinic acid > tolmetin = ketoprofen = fenbufen = indomethacin > fenoprofen > ibuprofen = (+)-naproxen = sulindac. Other anti-inflammatory analgesic drugs, including aspirin, diclofenac, diflunisal, meclofenamic acid, mefenamic acid, nambumetone, phenacetin, piroxicam, and phenylbutazone, failed to potentiate the GABA-antagonistic effect of norfloxacin. Felbinac (1 microM) increased the GABA-antagonistic potencies of norfloxacin and enoxacin about 26-fold, while increasing those of ciprofloxacin and pipemidic acid 7-fold and 2.3-fold, respectively. Using subsaturating concentrations of the four quinolones, concentration-response curves for felbinac yielded EC50 values ranging from 110 nM with 5 microM norfloxacin to 1.3 microM with 100 microM pipemidic acid. Three other piperazinoquinolone antibacterial agents (amifloxacin, difloxacin, and fleroxacin) and four nonpiperazinoquinolone anti-bacterial agents (oxolinic acid, cinoxacin, nalidixic acid, and piromidic acid) were much weaker GABA antagonists and were not significantly potentiated by felbinac. All other known GABAA receptor blockers tested, including R 5135, pitrazepin, bicuculline, SR 95531, strychnine, D-tubocurarine, thebaine, securinine, theophylline, and caffeine, were not potentiated by felbinac. Our results suggest that norfloxacin and related piperazinoquinolones, acting at GABAA receptors, may induce a high affinity binding site for indomethacin/ibuprofen-like anti-inflammatory agents (the AAA site) that, when occupied, reciprocally increases the affinities of the quinolones for GABAA receptors. The AAA binding site may be a new site in the GABAA receptor complex.

4-Quinolones↗

PubMedDate not supplied

Acute inhalation toxicity of neutralized chemical agent identification sets (CAIS) containing agent in chloroform.

An acute head-only inhalation study was conducted in rats exposed for 1 h to product solution (wastestream) resultant from the chemical neutralization of Chemical Agent Identification Sets (CAIS) containing agent (sulfur mustard (HD), nitrogen mustard (HN-1) or lewisite (L)) in chloroform. Groups of Sprague-Dawley rats were exposed to varying concentrations (24000, 18000, 12000 or 6000 ppm) of CAIS wastestream. An additional group was exposed to the vehicle (chloroform/t-butanol) only, at a concentration equivalent to the concentration of vehicle at the highest exposure level. Animals were evaluated for toxic effects, including assessment of toxicant-induced alterations to the ocular and respiratory systems. Mortality on exposure to 24000 ppm of test article or to vehicle alone was high. Mortality in the other exposure groups was roughly proportional to the concentration of test article (wastestream). Toxic signs were consistent with exposure to solvent system components (chloroform/t-butanol) and to agent decomposition products/by-products. Incidence and severity of ocular effects were similar in vehicle control and treatment groups. The salient respiratory effect observed was a decreased minute volume, which was also noted in vehicle and treatment groups.

Animals↗

PubMed1988

Gadolinium-labeled liposomes containing paramagnetic amphipathic agents: targeted MRI contrast agents for the liver.

Unique paramagnetic liposomal contrast agents were synthesized and utilized for selective augmentation of T1 MR imaging of the livers of normal Balb/c mice. Amphipathic gadolinium complexes, which mimic phospholipids, were incorporated into the lamella of small unilamellar liposomes (SUV) such that they became an integral part of its surface. T1 signal enhancement of normal liver approached 150% after iv administration of the paramagnetic liposomes, determined by experiments performed on a 1.9-T, experimental whole-body MRI unit. Tracer studies utilizing gadolinium-153-tagged SUV revealed that the agents exhibited excellent in vivo stability, compared to liposomal preparations in which paramagnetic agents are simply entrapped in the aqueous core of the liposome vesicle.

Animals↗

PubMed1985

Stability of solutions of antineoplastic agents during preparation and storage for in vitro assays. General considerations, the nitrosoureas and alkylating agents.

In vitro drug sensitivity of tumour biopsies is currently being determined using a variety of methods. For these chemosensitivity assays many drugs are required at short notice, and this in turn means that the drugs must generally be stored in solution. There are, however, a number of potential problems associated with dissolving and storing drugs for in vitro use, which include (a) drug adsorption; (b) effects of freezing; (c) drug stability under the normal conditions of dilution and setting up of an in vitro assay; and (d) insolubility of drugs in normal saline (NS) or phosphate-buffered saline (PBS). These problems are considered in general, and some recommendations for use of solutions of drugs in in vitro assays are suggested. The nitrosoureas and alkylating agents are also investigated in greater detail in this respect. The nitrosoureas are found to be very labile in PBS at pH 7, with 5% degradation (t0.95) occurring in 10-50 min at room temperature. These values are increased about 10-fold on refrigeration and about 5- to 10-fold on reduction of the pH of the medium to pH 4-5. At pH 7 and room temperature, t0.95 is observed in under 1 h with the alkylating agents nitrogen mustard, chlorambucil, melphalan, 2,5-diaziridinyl-3,6-bis(2-hydroxyethylamino)-1,4-benzoquinone (BZQ), dibromodulcitol, dibromomannitol, treosulphan, and procarbazine. Of the other alkylating agents, 4-hydroperoxycylophosphamide (sometimes used in vitro in place of cyclophosphamide), busulphan, dianhydrogalactitol, aziridinylbenzoquinone (AZQ), and dacarbazine have a t0.95 of between 2 and 24 h, while ifosfamide and pentamethylmelamine are both stable in aqueous solution for greater than 7 days. About half the drugs studied in detail have been stored frozen in solution for in vitro use, although very little is known about their stability under these conditions.

Alkylation↗

PubMed1993

Liposomes as carriers of antimicrobial agents or immunomodulatory agents in the treatment of infections.

Targeting of antimicrobial agents by means of liposomes is under investigation and may be of importance in the treatment of infections that prove refractory to conventional forms of antimicrobial treatment. The ability to achieve a significantly longer residence time of liposomes in plasma and limited uptake of liposomes by the mononuclear phagocyte system opens up new areas of investigation and potential therapeutic application. By manipulating the liposomal composition, rates of uptake and intracellular degradation can be influenced and thereby the rates at which liposome-encapsulated agents are released and become available to exert their therapeutic action. With respect to the targeting of macrophage modulators at the mononuclear phagocyte system by means of liposomes for maximal stimulation of the nonspecific antimicrobial resistance, experimental evidence is now available of the potential usefulness of liposomes as carriers of these agents. This approach may also be of importance for the potentiation of treatment of severe infections.

Animals↗

PubMed1993

Fluorinated and iodinated dopamine agents: D2 imaging agents for PET and SPECT.

A novel series of dual-labeling D2 dopamine agents (labeled with either 18F or 123I for PET or SPECT imaging, respectively) was investigated. Two desired fluorinated and iodinated dopamine agents, FIDA1, (S)-(-)-2-(2-fluoroethoxy)-5-iodo-3-methoxy-N-[(1-ethyl-2- pyrrolidinyl)methyl]-benzamide, and FIDA2, (R)-(+)-2,3-dimethoxy-5-iodo-N-[(1-(4'-fluorobenzyl)-2- pyrrolidinyl)-methyl]benzamide, were synthesized. Both compounds displayed high affinity to the D2 receptor of rat striatal membrane preparations (Kd = 0.13 and 0.02 nM for FIDA1 and FIDA2, respectively). The biodistribution study in rats exhibited high localization in the striata of the brain with the striatum/cerebellum ratio reaching 29.3 and 13.1 at 1 h post iv injection for FIDA1 and FIDA2, respectively. Imaging studies with [18F]- and [123I]FIDA2 in monkeys, with PET and SPECT, respectively, showed comparable high selective striatal uptake. These results suggest that they are potentially useful D2 dopamine receptor imaging agents for PET and SPECT.

Animals↗

PubMed1991

Structure-activity studies of antitumor agents based on pyrrolo[1,2-a]benzimidazoles: new reductive alkylating DNA cleaving agents.

Described herein are structure-activity studies of new antitumor agents based on the pyrrolo[1,2-a]benzimidazole (PBI) ring system. These compounds were designed as new DNA cross-linkers mimicking the mitomycin antitumor agents. Actually, the PBI derivatives were found to have anthracycline-like features: (i) shared cross resistance with doxorubicin in a human myeloma line, (ii) cardiotoxicity, and (iii) excellent DNA strand cleaving capability. The DNA strand cleavage is thought to result from reductive alkylation of DNA followed by the generation of reactive oxygen radicals. The best antitumor agent studied is 6-N-aziridinyl-3-hydroxy-7-methyl-2,3-dihydro-1H-pyrrolo- [1,2-a]benzimidazole-5,8-dione 3-acetate (PBI-A), which possesses nanomolar IC50 values against various human ovarian and colon cancer cell lines.

Alkylation↗

PubMed1985

A new class of cardiotonic agents: structure-activity correlations for natural and synthetic analogues of the alkaloid A new class of A new class of cardiotonic agents: structure-activity correlations for natural and synthetic analogues of the alkaloid pumiliotoxin B (8-hydroxy-8-methyl-6-alkylidene-1-azabicyclo[4.3.0]nonanes).

Pumiliotoxin B (PTX-B, 6-(6',7'-dihydroxy-2',5'-dimethyl-(E)-4'-octenylidene)-8-hydroxy-8 -methyl-1- azabicyclo-[4.3.0] nonane) increases the force of contractures of spontaneously beating guinea pig atrial strips by 3- to 5-fold with half-maximal effects at about 3 microM and increases rates of atrial contractions by 2- to 3-fold with half-maximal effects at about 6 microM. The presence of an axial 7-hydroxy substituent (PTX 339A) decreases the efficacy but not the potency of PTX-B as a positive inotropic agent while having only slight effects on activity as a positive chronotropic agent. The presence of an equatorial 7-hydroxy substituent (PTX 339B) greatly decreases efficacy and potency of PTX-B as a positive chronotropic and inotropic agent. Pumiliotoxin A which lacks the side-chain 7'-hydroxy group of PTX-B causes only a 2-fold increase in force of contracture at 54 microM while having minimal effects on rate. The presence of an axial 7-hydroxy substituent (PTX 323B' and 323B", epimeric at the 6'-hydroxy) markedly enhances positive inotropic and chronotropic effects of PTX-A. Another congener, PTX 251D with a 6-(2'-methylhexylidene) side chain, and a synthetic analogue with a 6-(6'-heptenylidene) side chain are cardiac depressants. Both lack hydroxyl groups in the side chain. The presence of an omega-1 hydroxy group in the side chain of PTX 251D yields an alkaloid (267C) with weak positive inotropic effects and minimal chronotropic effects. The presence of an axial 7-hydroxy group in the indolizidine ring of PTX 251D results in a compound (PTX 267A) with very weak positive inotropic effects while retaining the negative chronotropic effects of PTX 251D. A synthetic analogue with a 6-(7'-hydroxyheptylidene) side chain is a cardiac depressant even though it contains a side-chain hydroxyl corresponding in position to the 7'-hydroxyl of the side chain of PTX-B. The positive chronotropic and inotropic effects of pumiliotoxin B are reversed only by relatively high concentrations of the calcium channel blockers nifedipine and verapamil, suggesting that pumiliotoxin B may owe its cardiotonic activities to effects on internal mobilization of calcium.

Alkaloids↗

PubMed2002

Decreased actin solubility observed during ATP-depletion is mimicked by severing agents but not depolymerizing agents in isolated and cultured proximal tubular cells.

The microvilli of the apical membrane of proximal tubule (PT) cells are supported by the underlying actin cytoskeleton. Ischaemic or anoxic ATP-depletion leads to the disruption of the actin cytoskeleton, resulting in microvillar retraction and loss of membrane polarity. Using isolated PT cells, we have previously demonstrated that actin filaments (F-actin) are likely severed during ATP-depletion. A sequential extraction protocol revealed a decrease in actin solubility, resulting in the sequestration of a distinct F-actin pool with the insoluble cellular complex in ATP-depleted PT cells. We demonstrate here that decreased actin solubility is not only a reliable end-marker of ATP-depletion induced injury in freshly isolated PT cells, but also serves as a biochemical marker in the cultured proximal tubular cell line LLC-PK1. In the present studies, we also investigated specific actin-binding drugs to determine if they mimic the effects observed during energy depletion. Jasplakinolide (JP), a compound which binds F-actin and prevents depolymerization, did not effect actin solubility during ATP-depletion. Furthermore, swinholide A (SA), an F-actin severing agent, resulted in decreased actin solubility, mimicking the effects of ATP-depletion. Interestingly, latrunculin A (LA), an agent which depolymerizes F-actin, did not reduce actin solubility, but rather resulted in an increase in digitonin-soluble actin. Taken collectively, our results support previous work and suggest that disruption of the actin cytoskeleton during ATP-depletion is mediated by F-actin severing/fragmentation and not depolymerization. The differential effects of F-actin disrupting agents and the consistencies observed in both models of ischaemic injury will provide a basis for a more detailed understanding of the pathological events of PT-cell dysfunction.

Actins↗

PubMed2003

Congenital and acquired brain injury. 4. New frontiers: neuroimaging, neuroprotective agents, cognitive-enhancing agents, new technology, and complementary medicine.

UNLABELLED: This self-directed learning module explores the clinical application of new and evolving research frontiers in the field of neuroimaging, neuroprotective agents, and cognition-enhancing medications as applied to patients with brain injury. The current and potential clinical applications of robotic technology, virtual reality, and telemedicine in the field of physical medicine and rehabilitation is explored. The evidence to support a growing interest in and application of complementary medicine techniques in brain injury and other disorders is reviewed. OVERALL ARTICLE OBJECTIVES: (a) To explore the current research and potential clinical applications of medical and technologic advances in neuroprotective agents, cognition-enhancing agents, neuroimaging, virtual reality, robotics, and telemedicine as applicable to brain injury and (b) to identify the evidence to support an expanding use of complementary medicine in brain injury.

Brain Injuries↗

PubMed1984

Comparison of a centrally acting antihypertensive agent and beta-adrenergic blocking agents for the treatment of hypertension.

Centrally acting agents and the beta-adrenergic antagonists represent two classes of antihypertensive agents recommended for initial monotherapy. Comparisons of the efficacy and safety of the centrally acting agent, guanabenz, with those of propranolol and pindolol in patients with mild to moderately severe hypertension, are reported. In the guanabenz versus propranolol study, mean supine blood pressure decreased by 19/15 mm Hg for 44 guanabenz-treated patients and by 17/15 mm Hg for 52 propranolol-treated patients who completed 6 months of therapy. In the guanabenz versus pindolol study, the mean decrease in supine blood pressure was 17/14 mm Hg for the 12 patients treated with guanabenz and 21/15 mm Hg for the 13 patients who received pindolol and completed 2 months of therapy. If the patients who discontinued therapy for drug-related reasons are considered, the percentages of patients with clinically satisfactory blood pressure reductions were 59% for the guanabenz group versus 62% for the propranolol group and 79% for guanabenz-treated patients versus 64% for pindolol-treated patients. Although adverse effects, including dry mouth, drowsiness, and weakness, were more common among guanabenz-treated patients, these effects generally were mild and became less frequent with continued therapy. The therapeutic efficacy and safety of guanabenz were similar to those of the two beta-adrenergic blocking drugs, propranolol and pindolol. Guanabenz therapy decreased serum total cholesterol (p less than 0.05), whereas propranolol therapy decreased HDL cholesterol (p less than 0.05). Thus, guanabenz did not produce serum lipid abnormalities that may be associated with increased cardiovascular risk.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗