Mechanism of butyrate binding to histone deacetylase[HDAC] correlation with chemopreventive effects and ligand selectivity

Sodium butyrate [SB] is a natural cytodifferentiating and cancer preventive agent. These actions are largely triggered by inhibition of the HDAC enzyme, thereby inducing hyperacetylation/ transcription of certain genes. Unlike the prototype HDAC inhibitor, trichostatin-A [TSA], SB offers higher selectivity on cancer cells, with a lower affinity to HDAC. The mechanisms underlying these distinct biological profiles for SB remain undefined. We currently propose for, and attempt to identify differences in the binding of SB and TSA to the HDAC binding pocket. The lowest energy conformer of SB was prepositioned on TSA binding site of HDAC. Following minimization of the best-docked S8-HDAC complex, binding profiles, conformational changes and energy calculations have been derived. TSA elicited 4 hydrogen bonds with 3 key enzyme pocket residues [His131, His132 and Tyr297; bidentated]. SB missed a hydrogen bond with Tyr297 and caused more disruption of the pocket amino acid residues His131, His132 [RMS deviation value difference of up to 0.40 A]. Besides, a looser binding to the pivotal zinc atom of HDAC was evident with SB [1 vs. 2 bonds in case of TSA]. Likewise, SB was far loosely packed in the HDAC's binding tunnel as compared to TSA. Moreover, energy computations indicated that SB had a lower binding affinity than that of TSA [-27.8 vs. -66.3 Kcal/mol]. Detailed binding differences for both ligands are described. These studies demonstrate that SB binding to HDAC confers unique catalytic, conformational and computational characteristics consistent with a lower binding affinity to HDAC and a higher selectivity on cancer cells than TSA. These newly defined binding properties of SB can further state a framework strategy for the rational development of SB-like anticancer drugs with enhanced biological and safety profiles

Computational characteristics of valproic acid binding to histone deacetylase

Recently, the antiepileptic drug valproic acid [VPA] has also demonstrated efficacy in the management of cancer and bipolar disorders. These actions are largely mediated by inhibition of the HDAC enzyme/induction of certain genes. Relative to other HDAC inhibitors such as trichostatin-A [TSA], VPA offers higher selectivity on cancer cells with virtually no detrimental effects on normal cells. The molecular underpinnings of these biological profiles for VPA remain undefined. We currently propose for and attempt to identify differences in the binding of VPA and TSA to HDAC. In this paper, conformational changes and energy calculations have been derived. VPA had to accomplish conformational changes in its structure for best accommodation at the HDAC binding site. Energy computations showed that VPA has a lower binding affinity than TSA [-53.80 vs. -66.30 Kcal/mol]. These findings demonstrate that VPA binding to HDAC confers catalytic, conformational, and computational characteristics that are distinct from those of TSA. These findings for VPA are consistent with a moderate inhibition of HDAC, a low toxicity on normal cells, and a higher selectivity on cancer cells than TSA. Accordingly, these newly identified binding properties of VPA can state a framework strategy for the rational design of VPA-related anticancer drugs with superior cytodifferentiating- and/or safety-profiles

Resveratrol activates the kinase-G system in human coronary smooth muscle cells via a nongenomic, estrogen-independant mechanism

Resveratrol [RSVL], a polyphenolic phytoestrogen in grapes, confers multifaceted cardiovascular benefits. The cellular and molecular basis of RSVL actions has been largely undefined. Currently, in human coronary smooth muscle cells [HCSMCs], RSVL markedly [3.2 fold] enhanced cGMP formation [t1/2: 6.3 min, EC 50: 1.8 microM] and stimulated kinase-G activity [4 fold]. By contrast, RSVL had no effect on cAMP or PKA activity in these cells. The RSVL-enhanced cGMP/kinase-G activity was not abrogated by either of the phosphodiesterase-inhibitors [zaprinast, 10 microM, IBMX, 0.5mM], the nitric oxide synthase-inhibitor [L-NMMA, 10 microM], or the soluble guanylyl cyclase [sGC]-inhibitor [ODQ, 10 microM].In membrane preparations from HCSMCs, RSVL activated GC in the particulate-, but not in the soluble- membrane fraction. Similar effects were due to the specific particulate-GC [pGC] agonist atrial natriuretic peptide [ANP, 0.1-1 microM]. By contrast, the nitric oxide donor, SNAP [1-10 microM] stimulated GC only in the soluble fraction. Responses to RSVL were insensitive to the estrogen receptor blockers, tamoxifen and ICI-182,780. Conversely, pretreatment with the PKC activator, PMA [0.1 microM], a known desensitizer of pGC, markedly blunted the RSVL-enhanced GC-activity. These findings demonstrate that RSVL triggers a pGC-mediated stimulation of protein kinase-G in human coronary smooth muscle cells. This pathway appears to be independent of the conventional estrogen machinery and supports both vasodilatory and anti-atherogenic actions for RSVL

Antineoplastons: major players in the biochemical defensive system against cancer

Antineoplastons are naturally occurring peptides and amino acid derivatives that were originally isolated from human urine. They possess a broad-spectrum antitumor activity and seem to be much safer and specific than many of the available chemotherapeutic agents. Their selectivity is likely entailed to preferential interaction with cellular components or signaling mechanisms that predominate in cancer cells. Our studies on breast cancer- cell lines and -patients indicated the efficacy of antineoplaston-A10 and its derivatives as antimitotic, immunemodulator and cytodifferentiating agents. Moreover, phase-I and phase-II clinical trials implied the utility of antineoplastons in treating neoplasms of various origins. Combination with lower doses of known chemotherapeutic agents or in conjunction with radiotherapy was a promising therapeutic strategy. Such regimens were likewise effective in cases with recurrent or drug-resistant neoplasms. Intensive research is continuing to reveal more on antineoplastons and their biologic characteristics

Heterogeneity of the mechanisms underlying activation of adenylatecyclase by endothelin-1 in rabbit and bovine iris sphincter and tracheal smooth muscles

In the bovine and rabbit iris sphincters and tracheas, endothelin-l [ET -1] activated adenylate cyclase [AC] in a concentration-dependent manner. The rate of cAMP formation decreased in the order, bovine iris sphincter > rabbit trachea > > rabbit iris sphincter > > bovine trachea. Maximal values for AC activation in bovine iris sphincter and rabbit trachea were 398% and 392% of basal activity respectively. Pretreatment with indomethacin [1 [micro]M], a cyclooxygenase inhibitor, virtually abolished the increase by ET-1 of cAMP levels in rabbit trachea and bovine trachea [96% reduction]. In the rabbit iris sphincter, indomethacin and nordihydroguairetic acid [NDGA] [1 [micro] M] lipoxygenase inhibitor, brought about 60 and 28% reduction of ET -1 response, respectively. Co-treatment with both eicosanoid inhibitors [1 [micro] M, each] eliminated the ET-1-evoked cAMP formation. Quinacrine [50 [micro] M], a phospholipase A2 [PLA2] inhibitor, attenuated cAMP production by ET -1 at a less prominent rate than that of indomethacin [38 to 70% reduction in cAMP increments]. At odds, in the bovine iris sphincter, the cAMP response was unaltered by all prostanoid inhibitors. Moreover, challenge with nicardipine [-a] Ca [2+] channel blocker, trifluoperazine -a calmodulin inhibitor, or staurosporine -a PKC inhibitor, had no significant effect on the responsiveness to ET -1, suggesting lack of mediators in the coupling of ET - receptors to AC system, in the bovine iris sphincter. In conclusion, activation of AC by ET -1 may represent a widespread phenomenon in smooth muscles. The mechanism whereby ET -1 elicits cAMP production is diverse and may include eicosanoids both from cyclooxygenase and lipoxygenase origins as mediators

Evaluation of aspiration versus aspiration and steroid injection in wrist ganglla

Prospective randomized study compares treatment of dorsal wrist ganglia by aspiration only and aspiration plus injection of steroid. 82 consecutive patients with wrist ganglia were randomized into two groups. The first group, ganglia were aspirated and multi-punctured, the second group, ganglia were aspirated, multiply punctured and then injected with kenacort 40 mg/ml. The request for surgery was not refused, if asked for

Results of treatment of flexion deformity hip in poliomyelitis

1. The operative treatment of flexion deformity hip after poliomyelitis gave 83.33% satisfactory result. 2. Satisfactory result was more when the angle of deformity was less than 30 degrees. 3. The presence of associated flexion deformity knee is a cause of unsatisfactory result. 4. Soutter's operation is most suitable in flexion deformity less than 30 degrees. 5. Compell's operation is more suitable when the flexion deformity is more than 30 degrees. 6. Yount oepration had the least satisfactory result and can be used only as supplementary procedure to the two other operations

significance of osteo-medullography in tibial shaft fractures

This study inculdes 46 patients with fractures of the tibia. 22 patients had delayed union; osteomdullography was performed for these 22 patients. Osteomedullography was considered positive in 8 cases where venous circulation was demonstrated across the fractur site and were treated conservatively. Union occurred within 3 months. 14 cases showed negative signs as there was no venous circulation across the fracture site and trested by bone grafting