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Shahid Parvez

Publications and source records attributed to Shahid Parvez.

3 recordsLinked to original sources

A review on advantages of implementing luminescence inhibition test (Vibrio fischeri) for acute toxicity prediction of chemicals.

Evaluation of biological effects using a rapid, sensitive and cost effective method can indicate specific information on toxicity/ecotoxicity. Since assays based on animals, plants and algae are expensive, time consuming and require large sample volume, recent studies have emphasized the benefits of rapid, reproducible and cost effective bacterial assays for toxicity screening and assessment. This review focuses on a bacterial assay, i.e., Vibrio fischeri bioluminescence inhibition assay, which is often chosen as the first test in a test battery based on speed and cost consideration. The test protocol is simple and was originally applied for aqueous phase samples or extracts. The versatility of the assay has increased with subsequent modification, i.e., the kinetic assay for turbid and colored samples and the solid phase test for analyzing sediment toxicity. Researchers have reported the Vibrio fischeri bioluminescence assay as the most sensitive across a wide range of chemicals compared to other bacterial assays such as nitrification inhibition, respirometry, ATP luminescence and enzyme inhibition. This assay shows good correlations with other standard acute toxicity assays and is reported to detect toxicity across a wide spectrum of toxicants.

Aliivibrio fischeri↗

Wavelet analysis for neonatal electroencephalographic seizures.

Electroencepholographs (EEGs) of neonatal seizures differ from those of children and adults. This study evaluated whether wavelet transform analysis, a nonstationary frequency analysis of EEG, can recognize and characterize neonatal seizures. Twenty-second segments were analyzed from 69 EEG seizures in 15 neonatal patients whose seizures lasted 10 seconds or longer. The wavelet transform results were examined, as were EEG seizure durations and dominant frequencies. The wavelet transform results were correlated with the occurrence, after an 18-month follow-up, of postneonatal seizures. Wavelet transform analysis identified 40 seizures (58%) with a "sustained dominant frequency component" that lasted 10 seconds or longer and 29 seizures without a sustained dominant frequency component. The mean seizure duration of the 40 seizures with sustained dominant frequency components was 63.3 seconds, longer than the mean duration (33.6 seconds) of the seizures without sustained dominant frequency components, P < 0.01. Eleven patients manifested postneonatal epileptic seizures. Fifty-two EEG seizures in these 11 patients revealed more sustained dominant frequency components (74%) than 17 seizures in the 4 patients without postneonatal seizures (only 12%), P < 0.05. Wavelet transform analysis can identify neonatal EEG seizures and characterize their epileptic components. The presence of sustained dominant frequency components may predict postneonatal epileptic seizures.

Asphyxia Neonatorum↗

How high can we go with phenytoin?

Phenytoin is an effective anticonvulsant, but high serum phenytoin concentrations may be associated with serious toxicity. The upper limit for the therapeutic serum concentration of phenytoin is considered to be 80 micromol/L. However, in some situations higher serum concentrations are needed to control seizures. The authors describe a 9-year-old girl who needed concentrations twice the normal amount to control recurrent episodes of decreased levels of consciousness. Except for nystagmus, she had no other signs of phenytoin toxicity. This patient highlights the critical principle in therapeutic drug monitoring of individualizing drug therapy. Although some patients receiving phenytoin may achieve seizure control with "subtherapeutic" levels (i.e., <40 micromol/L), others may need supratherapeutic levels, as was the case with this patient. Clinicians should be careful not to treat "numbers" (i.e., serum concentrations), but rather the patient's clinical condition, with a careful balance between therapeutic advantage and adverse effects.

Anticonvulsants↗