Discovery of indoleninyl-pyrazolo[3,4-b]pyridines as potent chemotherapeutic agents against colorectal cancer cells

A new series of indolenines decorated with pyrazolo[3,4-b]pyridines were designed and synthesized in up to 96% yield from the acid-catalyzed cyclocondensation of 1,3-dialdehydes with 3-aminopyrazoles. X-ray crystallography on a representative derivative, 5n, revealed two close to planar conformations whereby the N-atom of the pyridyl residue was syn or anti to the pyrrole-N atom in the two independent molecules of the asymmetric unit. The computational and DNA binding data suggest that 5n is a strong DNA intercalator with the results in agreement with its potent cytotoxicity against two colorectal cancer cell lines (HCT 116 and HT-29). In contrast to doxorubicin, compounds 5k-o have higher druggability (compliance to more criteria stated in Lipinski's rule of five and Veber's rule), higher bioavailability, and better medicinal chemistry properties, indicative of their potential application as chemotherapeutical agents.

Structural insights and cytotoxicity evaluation of benz[e]indole pyrazolyl-substituted amides

Five new compounds of benz[e]indole pyrazolyl-substituted amides (2a-e) were synthesised in low to good yields via the direct amide-coupling reaction between a pyrazolyl derivative containing a carboxylic acid and several amine substrates. The molecular structures were determined by various spectroscopic methods, such as NMR (¹H, ¹³C and ¹⁹F), FT-IR and high-resolution mass spectrometry (HRMS). X-ray crystallographic analysis on the 4-fluorobenzyl derivative (2d) reveals the amide-O atom to reside to the opposite side of the molecule to the pyrazolyl-N and pyrrolyl-N atoms; in the molecular packing, helical chains feature amide-N‒H⋯N(pyrrolyl) hydrogen bonds. Density-functional theory (DFT) at the geometry-optimisation B3LYP/6-31G(d) level on the full series shows general agreement with the experimental structures. While the LUMO in each case is spread over the benz[e]indole pyrazolyl moiety, the HOMO spreads over the halogenated benzo-substituted amide moieties or is localised near the benz[e]indole pyrazolyl moieties. The MTT assay showed that 2e, exhibited the highest toxicity against a human colorectal carcinoma (HCT 116 cell line) without appreciable toxicity towards the normal human colon fibroblast (CCD-18Co cell line). Based on molecular docking calculations, the probable cytotoxic mechanism of 2e is through the DNA minor groove binding.

The 'Rastelli' operation--results at the Singapore General Hospital

Reconstruction of the right ventricular outflow tract in patients with right ventricle-pulmonary artery discontinuity with a valved conduit is well established. The aim of this study was to review our results at the Singapore General Hospital. Between October 1989 and May 1993, 13 patients underwent the 'Rastelli' operation. The mean age at definitive repair was 68 months. Ten patients had pulmonary atresia with ventricular septal defect, two patients truncus arteriosus (one patient each with type 3 and type 2) and one patient had tetralogy of Fallot with absent pulmonary valve syndrome. In 12 patients cryo-preserved pulmonary artery homografts with a mean diameter of 21mm (19-23mm) were used, and a 11mm composite Hancock dacron valved conduit in one patient. There were no operative deaths. The mean duration of follow-up is 37 months (23-48 months). All patients were well and in NYHA class I on recent follow-up. On echocardiographic assessment 12 patients had trivial or no gradient across the right ventricular outflow tract, while one patient had a gradient of 25mmHg. The "Rastelli" operation can be undertaken with low mortality and morbidity and early results are encouraging.

Percutaneous balloon pulmonary valvuloplasty--the Singapore General Hospital experience

Percutaneous balloon pulmonary valvuloplasty was performed in ten children aged 4 months to 9 years (mean age = 3.9 years). Their weights ranged from 5.6 to 38 kg (mean = 16.1 kg). Seven had typical pulmonary valve stenosis, two had pulmonary atresia and previous surgical valvotomy and one had dysplastic pulmonary valve. In patients with typical pulmonary valve stenosis, significant reductions in the right ventricular systolic pressure and pulmonary systolic pressure gradients were observed immediately after balloon dilatation. Follow-up evaluation by Doppler echocardiography at six months to two years showed further reduction in pulmonary gradients in five, and in the other two, the gradients remained low. Reduction in right ventricular pressure was less in patients with pulmonary atresia and previous surgical valvotomy and patients with dysplastic pulmonary valve. Balloon pulmonary valvuloplasty is a safe and effective procedure for the relief of typical pulmonary valve stenosis. In patients with pulmonary atresia and previous surgical valvotomy, balloon valvuloplasty can be an effective palliation for decompressing the right ventricle and improving pulmonary blood flow.

Balloon atrial septostomy under two dimensional echocardiographic visualisation

From May 1988 to January 1989, we performed balloon atrial septostomy under Two Dimensional Echocardiographic visualisation on 8 patients at the bedside in the intensive care unit, in the Singapore General Hospital. Their ages ranged from 3 to 45 days (median = 7 days). Their weights ranged from 1.6 to 4.0 kg (mean +/- 2sd = 3.2 + 1.6). Five patients had transposition of the great arteries, 1 had tricuspid atresia and 2 with pulmonary atresia/stenosis. There were no complications related to the procedure. The advantage of Two Dimensional Echocardiographic imaging compared to fluoroscopy are 1) excellent visualisation of cardiac structures, 2) it can be performed safely at the bedside without transporting patient to the cardiac catheter laboratory, 3) Immediate detection of cardiac complications and 4) no radiation exposure. Balloon atrial septostomy done using Two Dimensional Echocardiographic visualisation is acceptable and safe. It is the method of choice in our department.

Kawasaki disease--the Singapore experience

50 children with Kawasaki disease were seen between September 1983 to March 1988. Their ages ranged from 3 months to 10 years with a mean age of 25 months. Male to Female ratio was 2.3 to 1. The diagnosis of Kawasaki disease was made between the fourth to fifteenth day of illness. Marked thrombocytosis, raised erythrocyte sedimentation rate, leucocytosis, mild anemia and sterile pyuria were common features. All patients had a normal ECG and chest X-ray. 2D echocardiogram was done in the sub-acute phase of the illness in every patient. Sixteen patients (32%) had coronary artery dilatation. Thirteen of these had serial 2D echocardiograms done over a period of more than one year. Twelve had echocardiographic resolution of the coronary lesion within 18 months of follow up. Patients with coronary artery dilatation were significantly younger. All had full clinical recovery with aspirin therapy. Kawasaki disease afflicts mostly young children and can present as a diagnostic problem. Coronary artery involvement is common, and except for age, it is not predictable by any clinical or laboratory parameter. Serial echocardiographic examinations are necessary in the management of these patients.

Efficacy of verapamil in the conversion of supraventricular tachycardia in Singapore children

The efficacy of verapamil in the conversion of 47 episodes of supraventricular tachycardia in 22 children was evaluated. The age of the patients ranged from 15 days to 10 years. Tachycardia was the main mode of presentation. Ten out of 22 children had viral infections. Two patients developed mild cardiac failure. Six patients had underlying cardiac abnormalities. Forty-four out of 47 episodes of supraventricular tachycardia were converted to sinus rhythm by a single dose of verapamil (0.11 +/- 0.08 mg/kg). No significant side-effects were observed. Intravenous verapamil is an effective and safe drug for the conversion of supraventricular tachycardia in children.