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Biomedical subjects

R Ahmad

Publications and source records attributed to R Ahmad.

At least 73 records · Page 4Linked to original sources

Dyskinesias subside off all medication in a boy with autistic disorder and severe mental retardation.

A boy with autistic disorder and severe mental retardation developed severe dyskinesias, including objective akathisia (probable) and tics, a month after discontinuation of at least two years of treatment with drugs block dopamine receptors. These dyskinesias greatly subsided during a 17-wk. open-label nonblind clinical trial of clomipramine, and returned transiently when the parents abruptly discontinued clomipramine. However, the dyskinesias gradually subsided during two and a half years of follow-up with the boy being off all medication. A few stereotypies remain. We believe this suggests the hypothesis that movement disorders, such as withdrawal and tardive akathisia and tics, occurring in boys with autistic disorder treated with dopamine receptor-blocking drugs may subside months or years after discontinuation of the agents and that clomipramine may facilitate this process. We also hypothesize that some boys with autistic disorder and mental retardation exhibit fewer movement disorders, fewer psychiatric symptoms, and better over-all functioning after they have received no dopamine receptor-blocking drugs for several months, and this improvement continues years after the medication has ceased.

Akathisia, Drug-Induced↗

Detection of dengue virus from field Aedes aegypti and Aedes albopictus adults and larvae.

Mosquito adults and larvae were collected from dengue high risk areas and transported to the laboratory for identification. Identified mosquitos were pooled according to the species, date and locality and stored at -70 degrees C. A total of 1,385 pools of Aedes albopictus and 267 pools of Ae. Aegypti were collected from major towns in 12 states in Peninsular Malaysia. Virus isolation was carried out using cell culture (C6/36 clone) of Ae. albopictus and detection of dengue virus by the peroxidase anti-peroxidase staining. All positive isolations were further re-confirmed by the reverse transcriptase-polymerase chain reaction (RT-PCR). Most of the pools were negative with PAP staining and RT-PCR. However, 11 mosquito pools were positive with PAP staining. On the other hand, samples from Terengganu, Pulau Pinang and Johor were positive using both methods.

Adult↗

A recombination-efficient baculovirus vector for simultaneous expression of multiple genes.

The baculovirus system is an extremely powerful tool for expression of heterologous genes in eukaryotic environment. A multiple expression vector, pBacUCmP3, was constructed which harbored two copies of the Autographa californica nuclear polyhedrosis virus very late gene promoter and the Drosophila melanogaster 70-kDa heat-shock protein (hsp70) promoter with downstream unique restriction sites for cloning of three independent foreign genes. Co-transfection of pBacUCmP3 with Bsu36I-linearized viral DNA yields recombinant progeny viruses at very high frequencies. The utility of this multiple expression transfer vector was demonstrated using three heterologous reporter genes encoding the beta-subunit of the human chorionic gonadotropin hormone, firefly luciferase and the bacterial beta-galactosidase (beta Gal) enzyme. The expression of reporter genes, monitored at various times post-infection, confirmed that while beta-Gal synthesis was under the transcriptional control of the hsp70 promoter, the beta hCG and Luc proteins were synthesized as a function of polyhedrin promoter activation profile. This vector will be useful for multiple synthesis of proteins at different time points.

Animals↗

An FTIR spectroscopic study of calf-thymus DNA complexation with Al(III) and Ga(III) cations.

The interaction of calf-thymus DNA with trivalent Al and Ga cations, in aqueous solution at pH = 6-7 with cation/DNA(P) (P = phosphate) molar ratios (r) 1/80, 1/40, 1/20, 1/10, 1/4 and 1/2 was characterized by Fourier Transform infrared (FTIR) difference spectroscopy. Spectroscopic results show the formation of several types of cation-DNA complexes. At low metal ion concentration (r = 1/80, 1/40), both cations bind mainly to the backbone PO2 group and the guanine N-7 site of the G-C base pairs (chelation). Evidence for cation chelate formation comes from major shifting and intensity increase of the phosphate antisymmetric stretch at 1222 cm-1 and the mainly guanine band at 1717 cm-1. The perturbations of A-T base pairs occur at high cation concentration with major helix destabilization. Evidence for cation binding to A-T bases comes from major spectral changes of the bands at 1663 and 1609 cm-1 related mainly to the thymine and adenine in-plane vibrations. A major reduction of the B-DNA structure occurs in favor of A-DNA upon trivalent cation coordination.

Aluminum↗

Bifunctionality of the AcMNPV homologous region sequence (hr1): enhancer and ori functions have different sequence requirements.

The Autographa californica multinucleocapsid nuclear polyhedrosis virus (AcMNPV) homologous region sequence hr1 is a putative origin of replication (ori) sequence and can also function as a transcriptional enhancer for delayed-early genes. We demonstrate that this 750-bp sequence, carrying five 28-bp core palin-dromes, enhances expression from the very late polyhedrin promoter up to 11-fold in a classical enhancer fashion in transient expression assays. Enhancement is at the level of transcription, as evident from RNase protection assay analysis. It is mediated by an alpha-amanitin-insensitive RNA polymerase from the authentic polyhedrin promoter transcription start site and follows the temporal activation profile characteristic of the polyhedrin promoter. Three lines of evidence conclusively demonstrated that hr1 acts typically as an enhancer of polyhedrin gene transcription independent of its role as an ori: (i) linearized hr1-reporter plasmids, incapable of replicating in the host cell, could enhance transcription from the promoter; (ii) reporter plasmid copy number was not affected by the presence of aphidicolin during transfection; (iii) reporter plasmid DNA recovered from Sf9 cells was sensitive to Dpn I confirming its unreplicated state in the transfection regime followed by us. Molecular dissection of the hr1 sequence elements revealed that a core palindrome alone can function as an ori sequence whereas a palindrome along with flanking sequences is essential for the enhancer activity. Enhancement of luciferase expression from the polyhedrin promoter is a function of the number of core palindromes and flanking sequences. Our results demonstrate that hr1, which has several motifs for enhancer binding proteins and transcription factors, has a dual role associated with both DNA replication and transcriptional enhancement.

Animals↗

The effect of HCl on the solution structure of calf thymus DNA: a comparative study of DNA denaturation by proton and metal cations using Fourier transform IR difference spectroscopy.

The interaction of HCl with calf thymus DNA was investigated in aqueous solution at pH 7-2 with H+/DNA(P) (P:phosphate) molar ratios (r) of 1/80, 1/40, 1/20, 1/10, 1/4, 1/2, and 1, using Fourier Transform (FTIR) difference spectroscopy. Correlations between spectral changes, proton binding mode, DNA denaturation, and conformational variations are established. A comparison was also made between the ir spectra of denaturated DNA, in the presence of proton and Cu ions with similar cation concentrations. The FTIR difference spectroscopic results have shown that at low proton concentrations of r = 1/80 and 1/40 (pH 7-5), no major spectral changes occur for DNA, and the presence of H+ results in an increased base-stacking interaction and helical stability. At higher proton concentrations of r > 1/40, the proton binding to the cytosine and adenine bases begins with major destabilization of the helical duplex. As base protonation progresses, a B to C conformational conversion occurs with major DNA spectral changes. Protonation of guanine bases occurs at a high cation concentration r > 1/2 (pH < 3) with a major increase in the intensity of several DNA in-plane vibrations. Copper ion complexation with DNA exhibits marked similarities with proton at high cation concentrations (r > 1/10), whereas at low metal ion concentrations, copper-PO2 and copper-guanine N-7 bindings are predominant. No major DNA conformational transition was observed on copper ion complexation.

Animals↗

Left ventricular diastolic function in hypertensive patients with unstable angina and single coronary artery disease.

The present study was performed to investigate left ventricular diastolic (LVD) function in hypertensive patients with unstable angina. Three groups of 17 patients each were studied. Group 1 consisted of hypertensives with unstable angina (HTU); group 2, normotensives with unstable angina (NTU); and group 3, untreated, uncomplicated hypertensives (HT). The LVD function was assessed echocardiographically by transmitral valve Doppler flow to measure the ratio between the early diastolic filling (E) and the atrial contraction phase (A). An E/A ratio of < 1 was suggestive of LVD dysfunction. Left ventricular mass (LVM), from an M-mode echocardiogram using the Penn-Cube formula, was corrected to body surface area (LVM/S) using a standard nomogram. Data are represented as median values and analyzed by Mann-Whitney test. P was significant at < .05. The HTU group had an E/A ratio of 0.8, and the NTU and HT groups had ratios of 1.17 and 1.1, respectively. There was significant diastolic dysfunction in the HTU group compared with the NTU and HT groups (P = .037 and .049, respectively). Although the LVM/S was significantly higher in the HTU group when compared with the HT group (110.6 and 96.9, respectively, P = .017), there was no significant difference between the HTU and NTU groups (123.1), P = .67. Hypertensive patients with unstable angina have significant LVD dysfunction that seems to be independent of LVM and ischemia. This may be attributable to increased stiffness of the left ventricle or structural left ventricular abnormalities.

Adult↗

Case report: renal scintigraphy in the diagnosis of urinary extravasation.

Renal scintigraphy is a sensitive method for disclosing urinary extravasation. Its role following a road traffic accident is clearly presented in this case report. It is concluded that such a study can fill an important gap between the clinical and intravenous urography assessment and the more invasive studies in trauma victims.

Acute Kidney Injury↗

Oligospermia and its relation with hormonal profile.

Serum of 161 oligospermic men was analysed for pituitary hormones LH and FSH and the androgen testosterone. The hormonal analysis indicated normal levels of LH and testosterone, while the FSH levels showed negative correlation to the sperm concentration.

Adult↗

The effects of Cu2+ and Pb2+ on the solution structure of calf thymus DNA: DNA condensation and denaturation studied by Fourier transform ir difference spectroscopy.

The interaction of calf thymus DNA with Cu2+ and Pb2+ was studied in aqueous solution at pH 6.5 with metal/DNA (P) (P = phosphate) molar ratios (r) 1/80, 1/40, 1/20, 1/10, 1/4, 1/2, and 1, using Fourier Transform ir (FTIR) spectroscopy. Correlations between the ir spectral changes, metal ion binding mode, DNA condensation, and denaturation, as well as conformational features, were established. Spectroscopic evidence has shown that at low metal/DNA (P) molar ratios 1/80 and 1/40, copper and lead ions bind mainly to the PO2- of the backbone, resulting in increased base-stacking interaction and duplex stability. The major copper ion base binding via G-C base pairs begins at r > 1/40, while the lead ion base binding occurs at r > 1/20 with the A-T base pairs. The denaturation of DNA begins at r = 1/10 and continues up to r = 1/2 in the presence of copper ions, whereas a partial destabilization of the helical structure was observed for the lead ion at high metal ion concentration (r = 1/2). Metal-DNA binding also results in DNA condensation. No major departure from the B-family structure was observed, upon DNA interaction with these metal ions.

Animals↗

A tigogenin pentasaccharide from Cestrum diurnum.

A new steroidal saponin named diurnoside 1 has been isolated from a methanolic extract of fresh leaves of Cestrum diurnum and the structure, (25 R)-5 alpha-spirostan-3beta-yl-4-O-[2-O-(beta-D-gluco pyranosyl)-beta-D-glucopyranosyl]-3-O-[beta-D-xylopyranosyl]-beta-D- glucopyranosyl]-beta-D-galactopyranoside, was determined by modern NMR technique and chemical reactions.

Animals↗

Interaction of calf-thymus DNA with trivalent La, Eu, and Tb ions. Metal ion binding, DNA condensation and structural features.

The interaction of calf-thymus DNA with La3+, Eu3+ and Tb3+ has been investigated in aqueous solution at pH 6.5, using metal/DNA(P) molar ratios(r) 1/80, 1/40, 1/20, 1/10, 1/4 and 1/2. Correlations between FTIR spectral changes and DNA structural properties have been established. At low metal/DNA(P) (r) 1/80, the metal ions bind mainly to the PO2- groups of the backbone, resulting in increased base-stacking interaction and duplex stability. At (r) 1/40 and 1/20, metal ion binding to the PO2- and the guanine N-7 site (chelation) predominates with minor perturbations of the A-T base pairs. Evidence for this comes from the displacement of the band at 1712 cm-1 (T,G) towards a lower frequency and the PO2- antisymmetric band at 1222 cm-1 towards a higher frequency. At higher metal/DNA(P) ratio, r > 1/20, DNA begins to condensate and drastic structural changes occur, which are accompanied by the shift and intensity changes of several G-C and A-T absorption bands. No major departure from B-DNA conformation was observed before and after DNA condensation even though some local structural modifications were observed. A comparison with the Cu-DNA complexes (denaturated DNA) shows some degree of helical destabilization of the biopolymer in the presence of lanthanide ions.

Animals↗