Carlos Castillo-Henkel

Synthesis and evaluation of the cardiovascular effects of two, membrane impermeant, macromolecular complexes of dextran-testosterone

The incidence of cardiovascular disease is greater in men than in premenopausal women. Testosterone has been considered a significant risk factor for cardiovascular disease, but testosterones mechanism of action and its cellular site of action are still not clear. However, it is likely that non-genomic extracellular effects of the hormone are involved. With the aim of providing further information about this phenomenon, two membrane impermeant, macromolecular complexes of testosterone were synthesized and their cardiovascular effects were evaluated. We covalently bound testosterone (through carbon 3 or C-17 functional groups) to dextran (2 MDa) and evaluated its effects on isolated and perfused rat hearts (Langerdorff model). Our results showed that the macromolecular complexes increased vascular resistance similarly to free testosterone and blocked adenosine-induced vasodilatation. These effects were exerted rapidly and possibly through a non-genomic mechanism. Blockade of C-3 or C-17 functional groups by binding to macromolecular dextran induced no qualitative and/or quantitative changes in testosterone-induced effects.

Kidney damage after renal ablation is worsened in endothelial nitric oxide synthase (−/−) mice and improved by combined administration of L-arginine and antioxidants

Aim  Reduction in nitric oxide (NO) levels during kidney failure has been related to the reaction of NO with superoxide anions to yield peroxynitrite which possesses the biological activity responsible for renal damage. However, stimulation of the NO pathway ameliorates the progression of kidney failure. Thus, it is unclear whether NO prevents or acts as the compound responsible for the cytotoxicity observed during kidney failure.

Characterization of the potentiation of the antinociceptive effect of diclofenac by vitamin B complex in the rat

The role of vitamin B complex preparations as an analgesic adjuvant is controversial. Therefore, the purpose of the present study was to characterize the potentiation of the antinociceptive effect of diclofenac by a vitamin B complex preparation and its individual components by using the pain-induced functional-impairment model in the rat (PIFIR). Pain was produced by the intraarticular injection of uric acid in the right hind limb. Oral administration of diclofenac resulted in a dose-dependent antinociceptive effect. Oral administration of a vitamin B complex preparation containing thiamine (vitamin B(1)), pyridoxine (vitamin B(6)), and cyanocobalamin (vitamin B(12)) in a 1:1:0.01 proportion did not produce any antinociception by itself, but it significantly potentiated the effect of diclofenac. Coadministration of diclofenac with either thiamine or pyridoxine resulted in an antinociceptive effect similar to that of diclofenac alone. On the other hand, coadministration of cyanocobalamin significantly increased diclofenac-induced antinociception. It is concluded that the potentiation of diclofenac-induced antinociception in the PIFIR model is due to cyanocobalamin.

Bioassay‐guided isolation of an anti‐ulcer diterpenoid from Croton reflexifolius: role of nitric oxide, prostaglandins and sulfhydryls

Croton reflexifolius H. B. K (Euphorbiaceae) is a very common medicinal plant in the Huastecan region of Mexico that, according to local folk medicine, is considered useful in the treatment of gastritis and gastric ulcer. We have aimed to test the validity of this practice by using the experimental model of an ethanol‐induced gastric ulcer in male Wistar rats. The results showed that C. reflexifolius had gastroprotector activity, that the hexane extract had the highest protective activity (64.38 ± 7.72%), and that polyalthic acid isolated from this extract was the main active gastroprotector agent. Rats treated orally with polyalthic acid showed a gastroprotective effect similar to that elicited by carbenoxolone. As with carbenoxolone, the effect elicited by polyalthic acid was attenuated by pretreatment with either NG‐nitro‐l‐arginine methyl ester (70 mgkg−1, i.p.), a nitric oxide (NO) synthase inhibitor, or N‐ethylmaleimide (10 mgkg−1, s.c.), a blocker of sulfhydryl groups. This suggested that the gastroprotective mechanism of this diterpenoid involved the participation of both NO and endogenous sulfhydryl groups. Contrary to carbenoxolone, the gastroprotective effect of polyalthic acid was not affected by the inhibition of prostaglandin synthesis with indometacin (10 mgkg−1, s. c.). In conclusion, Croton reflexifolius contains compounds with gastroprotector activity. Polyalthic acid, which was isolated from this plant, was the main compound with gastroprotector activity, having effectiveness similar to that found with the use of carbenoxolone. Whereas NO and sulfhydryl groups were involved in the mechanisms of gastroprotective action of polyalthic acid, prostaglandins were not.

Bioassay-guided isolation of an anti-ulcer chromene from Eupatorium aschenbornianum: Role of nitric oxide, prostaglandins and sulfydryls

Eupatorium aschenbornianum is considered useful in the treatment of gastric ulcer. In the current study the validity of this practice was tested by using the experimental model of an ethanol induced gastric ulcer in rats. The results show that E. aschenbornianum had gastroprotective activity, that the hexane extract had the highest protective activity (85.65+/-4.76%), and that encecanescin isolated from this extract was the main active gastroprotective agent. The effect elicited by encecanescin was attenuated by N(G)-nitro-L-arginine methyl ester, N-ethylmaleimide and indomethacin, which suggests that NO, prostaglandins and sulfydryl groups are involved in the mechanisms of gastroprotective action.

Relaxant action mechanism of berberine identified as the active principle of Argemone ochroleuca Sweet in guinea‐pig tracheal smooth muscle

In this study we investigated the relaxant effect of the aerial parts of Argemone ochroleuca (Papaveraceae), which is used in Mexican traditional medicine for the treatment of various respiratory diseases such as cough, bronchitis and asthma. The alkaloid berberine was identified as one of the active relaxant principles (EC50 = 118.50 ± 3.91 μM) in the dichloromethane extract of A. ochroleuca (EC50 = 78.03 ± 2.15 μg mL−1 with 95.12 ± 3.56% of relaxation). Berberine concentration‐dependently relaxed the carbachol‐induced precontractions but not histamine‐ or KCl‐induced precontraction. The relaxant effect of berberine was unaffected by the presence of propranolol (3 μM), glibenclamide (10 μM) or ODQ (10 μM). However, 2′, 5′‐dideoxyadenosine (10 μM) blocked the log concentration‐response curves of berberine. On the other hand, berberine produced a leftward shift of the log concentration‐response curves of isoproterenol, forskolin and nitroprusside. Additionally, berberine produced a parallel rightward shift of the concentration‐response curve of carbachol in a competitive manner with a pA2 of 3.87 ± 0.045. The above results suggest that the relaxant effect of berberine on tracheal muscle is due to its antagonistic effect on muscarinic acetylcholine receptors.

Vitamin D receptor gene, biochemical bone markers and bone mineral density in Mexican women on dialysis

BACKGROUND The influence of the Bsm1 polymorphism of the vitamin D receptor (VDR) gene on mineral and bone disorders in chronic kidney disease (CKD) is still under discussion. The aim of this study was to analyse the relationship between VDR polymorphism, bone mineral density (BMD), biochemical bone markers and clinical factors in women on peritoneal dialysis (PD) and haemodialysis (HD). METHODS In a cross-sectional study, 197 women (42 +/- 10 years; 25% with diabetes mellitus (DM); body mass index (BMI) 25.26 +/- 4.77 kg/m(2)) treated by PD (72%) or HD (28%) underwent measurements of BMD (measured at the calcaneus by quantitative ultrasound; expressed as T- and Z-scores) and plasma total calcium (tCa), intact parathyroid hormone 1-84 (iPTH), phosphorus, albumin, glucose, osteoprotegerin (OPG), fetuin-A, intact osteocalcin-49 and N-MID fragment 1-43 aa (N-MID osteocalcin) N-terminal propeptide of type 1 procollagen (PINP) and C-terminal telopeptide-beta aspartic acid (BCL). DNA was extracted from peripheral blood. PCR products were digested with Bsm1 to analyse VDR polymorphism. RESULTS The Z-score of BMD was -1.1 +/- 1.03. According to the values of osteopenia (T-score = -1.0), patients with higher BMD were younger, had lower frequency of amenorrhoea and diabetes and had higher serum creatinine and fetuin levels as well as lower levels of PINP. In a stepwise multivariate logistics analysis, osteopenia was associated with presence of genotype BB+Bb (OR = 3.26, P < or = 0.003) and age (OR = 0.95, P = 0.050). According to the B allele, bb: n = 126 (64%) and BB+Bb: n = 71(36%), group bb had significantly higher mean Z-scores (-0.97 +/- 1.0 vs -1.3+/-0.92; P < or = 0.021). CONCLUSIONS The high frequency of osteopenia observed in female CKD patients on dialysis is associated with age and genetic predisposition as revealed by its association to the Bsm1 VDR polymorphism.

Polyalthic Acid Isolated from Croton reflexifolius has Relaxing Effect in Guinea Pig Tracheal Smooth Muscle

The relaxing activity of Croton reflexifolius H.B.K (Euphorbiaceae) leaves was assessed in isolated guinea pig tracheal rings. The dichloromethane extract of C. reflexifolius was the most active relaxant (EC50 = 118.98 ± 5.927 μ g/mL), and within this extract polyalthic acid was identified as the main active relaxing agent. Polyalthic acid showed a relaxing effect on tracheal rings precontracted with carbachol (EC50 = 183.71 ± 3.28 μM), histamine (6.24 ± 0.28 μM), and KCl (195.79 ± 10.36 μM). The pretreatment with polyalthic acid did not affect the concentration response curve to histamine, and it reduced the Emax of carbachol without affecting its EC50, thus suggesting that polyalthic acid produces a mild antimuscarinic activity. In addition, neither glibenclamide, l-NAME nor propranolol modified the effect of polyalthic acid, although the latter enabled isoproterenol activity. In conclusion, this study represents the first in which the relaxing effect of C. reflexifolius on tracheal rings of guinea pig was clearly demonstrated. Polyalthic acid, which was the main active agent in this relaxing action, produced a mild antimuscarinic activity in a noncompetitive manner. Its relaxing effect was independent of the contractile agent employed and was not related with β -adrenergic receptors, K channels, or nitric oxide. Further experiments are needed to clarify the mechanism of action of polyalthic acid.