In vivo adrenocorticotropin-releasing activity of neurohypophyseal hormones and their analogs

The ability of 21 neurohypophyseal hormones and related synthetic peptides to raise plasma ACTH or corticosterone concentrations was studied in female rats anesthetized with chlorpromazine, morphine, and pentobarbital. Corticotropin-releasing factor (CRF) activity was significantly correlated with pressor but not with antidiuretic or oxytocic activity. However, peptides with little or no pressor but very potent antidiuretic activity had weak CRF activity if given in a dose greater than 4 antidiuretic units/100 g BW; the dose-response slopes of these analogs were significantly flatter than that of arginine vasopressin. Pretreatment with antagonists with antipressor but not antiantidiuretic activity consistently reduced the CRF activity of the analogs with potent pressor activity. We conclude that the CRF activity of the neurohypophyseal hormones is primarily related to pressor activity.     

Action of hydrolyzed cisplatin and some analogs on microtubule protein polymerization in vitro

The inhibition of tubulin microtubule polymerization by cisplatin was investigated. The interaction was monitored by turbidity measurements and electron microscopy. For a 2.5 x 10(-5) M concentration of cisplatin, the inhibition at 37 degrees C was nearly 50% after 1 hour of incubation and 80% after 2 hours. A similar but lesser effect was observed after incubation at 4 degrees C. One analog of cisplatin, sulfato-aqua(1,2)diamminocyclohexane platinum II, showed the same inhibition effect.     

In vivo and in vitro effectivity of some platinum complexes

The following platinum complexes have been tested: cis-DDP--cis-diamminedichloroplatinum(II), Platinex--1,2-diaminocyclohexaneplatinum(II)citrate, Platuran--1,2-diaminocyclohexaneplatinum(II)-glucarate , TMA--1,2-diaminocyclohexaneplatinum(II)-4-carboxyphthalate,o xo-PT--cis-diamminedichloro-trans-dihydroxyplatinum(IV), CHIP--cis-dichloro-bis-(isopropylamine)-trans-dihydroxyplatinum(IV ), CBDCA--cis-diammine-cyclobutane-1,1-dicarboxylatoplatinum(II ). The activity of all tested complexes againt L1210 cells was higher in soft agar colony assay when compared with suspension culture of the same target cells. Using various doses and schedules oxo-Pt, CBDCA and cis-DDP exhibited the highest in vivo activity against P388 leukemia.     

Estrogenic activity of phenol red

It has recently been reported that phenol red, a pH indicator present in most tissue culture media, is a weak estrogen that can stimulate some estrogen-sensitive cells. However, the relative impact of phenol red on various cell lines is controversial. We examined the effect of phenol red on several estrogen-responsive cell systems that we use to study estrogen action. These included estrogenic stimulation of progesterone receptor and growth in human breast cancer-derived MCF-7 cells, stimulation of growth in human breast cancer-derived T47D cells, stimulation of prolactin synthesis in primary cultures of immature rat pituitary cells, and stimulation of progesterone receptor in primary cultures of immature rat uterine cells. Estrogenic responses in MCF-7 cells were the most sensitive to the presence of phenol red, while the other three cell cultures showed lesser effects of the indicator. In addition to intrinsic differences in cell responses, there were several other factors involved. These included differences in the estrogenic activity of phenol red-containing media and phenol red itself from different commercial suppliers, and differences in the concentration of free phenol red in final media due to binding of the indicator by serum. Higher concentrations of serum reduced the impact of phenol red on estrogenic responses in primary pituitary cells. Phenol red added to rat uterine cytosol competed with estradiol for binding to the estrogen receptor (relative binding affinity (RBA) approx. 0.001), and the acidic and basic forms of the indicator showed similar activity. Some commercial phenol red samples inhibited cell growth at levels of 100 mg/l; these effects were toxic rather than antiestrogenic, because growth inhibition could not be competitively reversed by an excess of estradiol. The amount of the indicator bound to serum in the final media, the source of the phenol red and the sensitivity of different cell types to the indicator ultimately determine its influence to the response of cells in tissue culture.     

In vitro and in vivo trypanocidal activity of some benzimidazole derivatives against two strains of Trypanosoma cruzi

The trypanocidal effect of five benzimidazole derivatives (1-5) was determined in vitro and in vivo assays against two strains of Trypanosoma cruzi (NINOA and INC5). The in vitro trypanocidal activity was evaluated by measuring the percentage of lysis of bloodstream trypomastigotes of T. cruzi. Results point to 5-chloro-1H-benzimidazole-2-thiol (1) as the best activity profile compound with a 50% lytic concentration (LC(50)) of 0.014 mM (NINOA strain) and 0.32 mM (INC5 strain). Reference drugs were nifurtimox (Nfx) and benznidazole (Bnz), which on NINOA strain displayed a LC(50)=0.60 mM and LC(50)=0.78 mM, respectively; while on INC5 strain they exhibited LC(50) values of 0.31 mM and 0.69 mM, respectively. The in vivo trypanocidal activity of 1-5 on parasitemia in a murine model acute Chagas' disease indicated that 1 and Nfx showed similar activity on INC5 strain, while 5-chloro-1-methyl-1H-benzimidazole-2-thiol (2) and its regioisomer, 6-chloro-1-methyl-1H-benzimidazole-2-thiol (3), displayed better activity than Nfx and Bnz on NINOA strain. All compounds showed low cytotoxicity against Vero cells, with selective index 38-3000 times higher to the parasite.     

Antibacterial activity of Co-trimazine in vitro and in vivo

Summary Co-trimazine is a new drug combination especially designed for the treatment of urinary tract infections. It consists of trimethoprim (90 mg) and sulphadiazine (410 mg). When combined in vitro, the components show high activity and a high frequency of synergy against urinary tract pathogens. After oral absorption sulphadiazine has a serum half-life similar to that of trimethoprim and is excreted in active form into the urine to a much higher degree than sulphamethoxazole. The ratio of the concentrations of trimethoprim and sulphadiazine in the urine following co-trimazine is favourable for a strong synergistic action between the compounds. In cross-over studies in volunteers receiving repeated daily doses of co-trimazine, either 500 mg twice daily or 1000 mg once daily, it was found that the antibacterial activity in the urine was at least as high as that provided by co-trimoxazole (2 × 960 mg) and considerably higher and more uniform than that given by nitrofurantion (3 × 50 mg).

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Die antibakterielle Aktivität in vitro und in vivo von Co-trimazine

Zusammenfassung Co-trimazine ist eine neue Kombination aus Trimethoprim (90 mg) und Sulfadiazin (410 mg), die besonders für die Behandlung von Harnwegsinfektionen entwickelt worden ist. Kombinationen von Trimethoprim und Sulfadiazin zeigen in vitro eine hohe Aktivität und in hohem Ausmaße synergistische Wirkung gegen Erreger der Harnwegsinfektionen. Nach oraler Gabe zeigt Sulfadiazin praktisch dieselbe Halbwertszeit in Serum wie Trimethoprim und wird in viel höherem Ausmaß als Sulfametoxazol in aktiver Form in den Harn ausgeschieden. Das Konzentrationsverhältnis Trimethoprim zu Sulfadiazin, das in Harn von Co-trimazine gegeben wird, begünstigt eine synergistische Wirkung zwischen den beiden Komponenten. In Cross-over-Versuchen bei Freiwilligen mit wiederholter Gabe zeigte Co-trimazine (2 × 500 mg und 1 × 1000 mg) eine antibakterielle Aktivität im Harn, die mindestens so hoch war wie die von Co-trimoxazole (2 × 960 mg) und deutlich höher und gleichmäßiger als die von Nitrofurantoin (3 × 50 mg).

     

The microfilaricidal activity of ivermectin in vitro and in vivo

Ivermectin has been tested against the microfilariae of Onchocerca lienalis, Brugia pahangi and Dirofilaria immitis in vitro and in vivo. All in vitro tests were performed on larvae incubated for 48 hours at 37 degrees C in Hepes buffered medium 199 containing 20% serum, benzylpenicillin and streptomycin. In vivo tests were performed on larvae in female BALB/C mice dosed with ivermectin, 5 mg/kg, orally. The microfilariae of B. pahangi in vitro were insensitive to ivermectin at concentrations to 30 ng/ml. In vivo, an 87% reduction in the level of microfilaraemia was obtained by 24 hours after drugging but no reduction was observed in the numbers of peritoneal microfilariae. O. lienalis microfilariae in vitro were killed by ivermectin at 3 ng/ml and the larvae of this species within the subcutaneous and cutaneous tissues of the mouse were also eliminated by ivermectin at 5 mg/kg. D. immitis larvae within the bloodstream of the mouse were also sensitive to ivermectin at the dosage employed but were unaffected by ivermectin in vitro at concentrations up to 30 ng/ml.     

Biological activity assessment of 1 alpha,25-dihydroxyvitamin D3-26,23-lactone and its intermediate metabolites in vivo and in vitro

The biological activity of 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3], 23(S)25(R)-1 alpha,25(OH)2D3-26,23-lactone, and three intermediate metabolites of the lactone in vivo and in vitro was comparatively examined. The three intermediate metabolites, 1 alpha,25(R)26(OH)3D3, 1 alpha,23(S)25(R)26(OH)4D3, and 23(S)25(R)-1 alpha,25(OH)2D3-26,23-lactol, stimulated increases, as did 1 alpha,25(OH)2D3, in intestinal calcium transport and serum calcium level in vitamin D-deficient rats fed a low-calcium diet. On the other hand, 23(S)25(R)-1 alpha,25(OH)2D3-26,23-lactone increased the calcium transport but decreased the serum calcium level. 1 alpha,25(OH)2D3,23(S)25(R)-Lactone and the other three metabolites stimulated multinucleate cell formation from hematopoietic blast cells in a manner correlated with their binding affinities for the 1 alpha,25(OH)2D3 receptor. But 23(S)25(R)-lactone did not show any inhibitory effect on the multinucleate cell formation induced by 1 alpha,25(OH)2D3 in contrast to the results obtained from unfractionated marrow cultures. Conditioned medium obtained from 23(S)25(R)-lactone-treated MC3T3-E1 cells inhibited the formation, probably by the action of some inhibitory factors elaborated by the cells treated with the lactone, whereas conditioned medium obtained from 1 alpha,25(OH)2D3 or other metabolite-treated MC3T3-E1 cells stimulated the formation. These findings suggest that 23(S)25(R)-1 alpha,25(OH)2D3-26,23-lactone might inhibit bone resorption through an inhibition of osteoclastic cell formation and that other vitamin D3 metabolites stimulate bone resorption by development of new osteoclastic cells in addition to indirect osteoclast activation.     

Investigation of antitumor effects of synthetic epothilone analogs in human myeloma models in vitro and in vivo

26-Trifluoro-(E)-9,10-dehydro-12,13-desoxyepothilone B [Fludelone (Flu)] has shown broad antitumor activity in solid tumor models. In the present study, we showed, in vitro, that Flu significantly inhibited multiple myeloma (MM) cell proliferation (with 1-15 nM IC50), whereas normal human bone marrow stromal cells (HS-27A and HS-5 lines) were relatively resistant (10- to 15-fold higher IC50). Cell-cycle analysis demonstrated that Flu caused G2/M phase arrest and induced cell apoptosis. After Flu treatment, caspase-3, -8, and -9 were activated, cytochrome c and second mitochondrial-derived activator of caspase were released to the cytosol, and c-Jun N-terminal kinase was activated, indicating that mitochondria were involved in the apoptosis. Flu toxicity to human hematopoietic stem cells was evaluated by CD34+ cell-apoptosis measurements and hematopoietic-progenitor assays. There was no significant toxicity to noncycling human CD34+ cells. We compared the efficacy of Flu with the epothilone analog 12,13-desoxyepothilone B (dEpoB) in xenograft nonobese diabetic/severe combined immunodeficient mouse models with subcutaneous or disseminated MM. Flu caused tumor disappearance in RPMI 8226 subcutaneous xenografts after only five doses of the drug (20 mg/kg of body weight), with no sign of relapse after 100 d of observation. In a disseminated CAG MM model, mice treated with Flu had a significantly decreased tumor burden, as determined by bioluminescence imaging, and prolonged overall survival vs. mice treated with dEpoB or vehicle control, indicating that Flu may be a promising agent for MM therapy.     

In vitro and in vivo antitumor activity of melatonin receptor agonists

Abstract: Melatonin has been shown to inhibit the proliferation of estrogen receptor α (ERα)‐positive human breast cancer cells in vitro and suppress the growth of carcinogen‐induced mammary tumors in rats. Melatonin’s antiproliferative effect is mediated, at least in part, through the MT1 melatonin receptor and mechanisms involving modulation of the estrogen‐signaling pathway. To develop melatonin analogs with greater therapeutic effects, we have examined the in vitro and in vivo antimitotic activity of two MT1/MT2 melatonin receptor agonists, S23219‐1 and S23478‐1. In our studies, both agonists are quite effective at suppressing the growth of MCF‐7 human breast cancer cells. At a concentration of 10^?6 m , S23219‐1 and S23478‐1 inhibited the growth of MCF‐7 cells by 60% and 73%, respectively. However, S23478‐1 is more effective than melatonin and S23219‐1 at repressing the expression and transactivation of the ERα, and modulating the expression of pancreatic spasmolytic polypeptide (pS2), an estrogen‐regulated gene. The melatonin agonist S23478‐1 exhibited enhanced antitumor potency in the subsequent studies in our animal model. At a dosage of 25 mg/kg/day, S23478‐1 is more efficacious than melatonin at inducing regression of the established N‐nitroso‐N‐methyl‐urea‐induced rat mammary tumors. This dose of S23478‐1 (25 mg/kg/day) generated a significant (P < 0.05) overall regression response of 52%. Furthermore, at this dosage, S23478‐1 is more effective than melatonin at suppressing the estrogen‐signaling pathway and promoting tumor cell apoptosis, significantly increasing the expression of the pro‐apoptotic protein Bax, while decreasing the expression of ERα and the anti‐apoptotic protein Bcl‐2.     

Hydrazide antidepressants possess novel antileishmanial activity in vitro and in vivo

The hydrazide monoamine oxidase inhibitor antidepressants possess a novel antiparasitic action against visceral and cutaneous strains of Leishmania. In vitro, phenelzine was the most active compound tested, while in vivo, nialamide was more potent, and was also effective when applied topically to cutaneous lesions. Despite the coincidence of tricyclic antidepressants also possessing antileishmanial activity, the evidence suggests that the antiparasitic action of the hydrazides is unrelated to either monoamine oxidase inhibition or CNS effects.     

Highly potent,synthetically accessible prostratin analogs induce latent HIV expression in vitro and ex vivo

Highly active antiretroviral therapy (HAART) decreases plasma viremia below the limits of detection in the majority of HIV-infected individuals, thus serving to slow disease progression. However, HAART targets only actively replicating virus and is unable to eliminate latently infected, resting CD4⁺ T cells. Such infected cells are potentially capable of reinitiating virus replication upon cessation of HAART, thus leading to viral rebound. Agents that would eliminate these reservoirs, when used in combination with HAART, could thus provide a strategy for the eradication of HIV. Prostratin is a preclinical candidate that induces HIV expression from latently infected CD4⁺ T cells, potentially leading to their elimination through a virus-induced cytopathic effect or host anti-HIV immunity. Here, we report the synthesis of a series of designed prostratin analogs and report in vitro and ex vivo studies of their activity relevant to induction of HIV expression. Members of this series are up to 100-fold more potent than the preclinical lead (prostratin) in binding to cell-free PKC, and in inducing HIV expression in a latently infected cell line and prostratin-like modulation of cell surface receptor expression in primary cells from HIV-negative donors. Significantly, selected members were also tested for HIV induction in resting CD4⁺ T cells isolated from infected individuals receiving HAART and were found to exhibit potent induction activity. These more potent agents and by extension related tunable analogs now accessible through the studies described herein should facilitate research and preclinical advancement of this strategy for HIV/AIDS eradication.