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Biomedical subjects

K Hasan

Publications and source records attributed to K Hasan.

11 recordsLinked to original sources
PubMed2004

The effect of remifentanil on the middle latency auditory evoked response and haemodynamic measurements with and without the stimulus of orotracheal intubation.

BACKGROUND AND OBJECTIVE: Changes in the middle latency auditory evoked response following the administration of opioids have been shown. However, it remains unclear as to whether these changes are due to a direct depressant effect of opioids on the middle latency auditory evoked response itself, or an indirect effect on account of their action in attenuating central nervous system arousal associated with noxious stimuli. By comparing changes in the middle latency auditory evoked response in intubated and non-intubated patients, receiving saline or remifentanil in different doses, this study attempts to answer this question. METHODS: Fifty-four patients were anaesthetized with isoflurane and nitrous oxide (0.9 MAC) and randomized to 1-6 groups. Groups 1-3 received a bolus injection of either saline 0.9%, low-dose remifentanil (1 microg kg(-1)) or high-dose remifentanil (3 microg kg(-1)) prior to intubation of the trachea. Groups 4-6 were not intubated following the bolus injection. RESULTS: Pa and Nb amplitudes of the middle latency auditory evoked response increased by 82% and 79% with intubation in the saline group (P < 0.005) and these changes were not seen in the patients given remifentanil. There was a significant linear trend for the reduction in Pa and Nb amplitude with increasing remifentanil dose (P < 0.05). In the absence of endotracheal intubation remifentanil had no effect on either the amplitudes or latencies of the waves Pa and Nb and there was no effect of dose. For the haemodynamic measurements remifentanil attenuated the pressor response to intubation (P < 0.001) and had a significant dose-related effect (P < 0.001) in the absence of intubation. CONCLUSIONS: We demonstrated an effect of remifentanil on both the middle latency auditory evoked response and haemodynamic changes to endotracheal intubation. For the non-intubated patients there was only an effect of remifentanil on the haemodynamic measurements. This suggests that remifentanil has an effect on the middle latency auditory evoked response in attenuating the arousal associated with intubation of the trachea but has no effect in the absence of a stimulus.

Adult↗
PubMed2003

Pregnancy and lymphangioleiomyomatosis: anaesthetic management.

Lymphangioleiomyomatosis is a rare, progressive cystic pulmonary disease related to tuberous sclerosis complex, affecting almost exclusively females of childbearing age. Progression of the disease is variable but may lead to terminal respiratory failure. As the disease may be oestrogen-dependent, it can arise de novo in pregnancy or established disease may undergo exacerbation. We report on the successful labour and delivery of such a patient and present the results of an internet survey of 30 pregnancies in 15 patients worldwide with lymphangioleiomyomatosis conducted by our patient before delivery.

Journal Article↗
PubMed2001

Tracheobronchopathia osteoplastica: incidental finding at tracheal intubation.

Subglottic papillomatous growths were observed on routine tracheal intubation for a scheduled colorectal procedure. Fibreoptic bronchoscopy revealed that the lesions extended down to the carina and into the main bronchi. The diagnosis of tracheobronchopathia osteoplastica was made after subsequent bronchoscopy and biopsy in the post-operative period. A brief review of this rare benign condition is given.

Aged↗
PubMed2001

Structural connectivity in white matter using the projected diffusion-tensor distance.

Diffusion tensor imaging (DTI) has become a powerful tool for analyzing the structure of white matter. We have proposed a method for detecting nerve fiber bundles in white matter using diffusion tensor images and have applied the method to in vivo brain measurements. Although there are many methods to investigate the connectivity of white matter that are based on principal eigenvector or full tensor propagation. In the proposed method, we use directional diffusion measurements to infer regional white matter connectivity. To assess the connectivity, we compose the map based on the projected tensor distance, then we put a label on the constructed map and segment regionally connected white matter using labels. The purpose of this study is to obtain a quantitative map of white matter connectivity in vivo using diffusion tensor properties.

Algorithms↗
PubMed2000

A geometric analysis of diffusion tensor measurements of the human brain.

The degree of diffusion tensor anisotropy is often associated with the organization of structural tissues such as white matter. Numerous measures of diffusion anisotropy have been proposed, which could lead to confusion in interpreting and comparing results from different studies. In this study, a new method for representing the diffusion tensor shape, called the three-phase (3P) plot, is described. This is a graphical technique based upon a barycentric coordinate system, which weights the tensor shape by a combination of linear, cylindrical, and spherical shape factors. This coordinate system can be used to map and potentially segment different tissues based upon the tensor shape. In addition, the 3P plot can be used to examine the shape properties of existing measures of diffusion anisotropy. In this paper, the 3P plot is used to compare four well-known anisotropy measures: the anisotropy index, the fractional anisotropy, the relative anisotropy, and the volume fraction. Computer simulations and diffusion tensor images of normal brains were obtained to study the properties of this new mapping technique. Magn Reson Med 44:283-291, 2000.

Anisotropy↗
PubMed1993

Inhibition of nitric oxide formation by guanidines.

Aminoguanidine, N,N'-diaminoguanidine, methylguanidine, and 1,1-dimethylguanidine were compared to NG-monomethyl-L-arginine (L-NMMA) for their ability to inhibit nitric oxide (NO) formation by cytokine-inducible and vascular constitutive isoforms of NO synthase. These comparisons were performed by assessing (1) cytokine-induced production of nitrite by RINm5F cells, (2) vasoconstrictor responses of isolated rat mesenteric arteries, and (3) in vivo blood pressure responses following intravenous bolus injection into anesthetized rats. Aminoguanidine and L-NMMA were the most potent inhibitors of cytokine-induced NO formation in RINm5F cells, while the other guanidine compounds were 10 (1,1-dimethylguanidine) to 100 (methylguanidine) times less potent. L-NMMA and 1,1-dimethylguanidine were the most potent inhibitors of the vascular constitutive isoform of NO synthase in both assay systems, while aminoguanidine and N,N'-diaminoguanidine were the least potent. These results (1) confirm the selective inhibition of the inducible isoform of NO synthase by aminoguanidine, (2) indicate that N,N'-diaminoguanidine, while approximately 30 times less potent than aminoguanidine in inhibiting inducible NO synthase, has very little effect on constitutive NO synthase activity, and (3) 1,1-dimethylguanidine, like L-NMMA, is a relatively potent inhibitor of both isoforms of NO synthase.

Amino Acid Oxidoreductases↗
PubMed1990

Contraindication to thrombolytic therapy in accidental hypothermia simulating acute myocardial infarction.

A 35-year-old schizophrenic patient was admitted to the Coronary Care Unit with shock, bradycardia and ST-T changes mimicking acute myocardial infarction. The rectal temperature was 33.6 degrees C and the diagnosis of accidental hypothermia was established. Accidental hypothermia must be considered in the differential diagnosis of acute myocardial infarction before instituting thrombolytic therapy.

Adult↗
PubMed1982

Hb Bart's level in cord blood and deletions of alpha-globin genes.

The white blood cell DNA of 36 cord blood samples with Hb Bart's in the red blood cells was studied for alpha-globin gene deletions by hybridization of DNA fragments digested by the restriction endonucleases Eco RI, Hpa I, Bam HI, and Bgl II. All 16 DNA samples from cord blood with Hb Bart's below 3% and no other abnormal hemoglobin had one alpha-globin gene deletion (alpha thal2), except one which had two alpha-globin gene deletions (alpha thal1). Most of the alpha thal2 were of the rightward deletion alpha thal2 genotype. Two new types of alpha thal2 variation was found, probably due to a polymorphism somewhere in an area outside the alpha-globin gene. All 14 cases with Hb Bart's between 3.5% and 8.5% and no other abnormal hemoglobin had two alpha-globin gene deletions (alpha thal1), except one that did not have any alpha-globin gene deletion and one that had one alpha-globin gene deletion. Three DNA samples of cord blood with Hb Bart's accompanied by Hb CoSp did not have any alpha-globin gene deletion. Sixty-five DNA samples from cord blood without Hb Bart's or other abnormal hemoglobin had no alpha-globin gene deletions, except one that had one alpha-globin gene deletion (alpha thal2). Two of the 65 DNA samples were found to have triplicated alpha-globin gene loci.

DNA↗
PubMed1978

Tinidazole and metronidazole in hepatic amoebiasis.

The efficacy of metronidazole and tinidazole has been compared in 31 patients with hepatic amoebiasis. Only those with unequivocal clinical, radiological and laboratory evidence of hepatic amoebiasis were included; diagnostic and therapeutic aspiration was performed where necessary. 15 patients received metronidazole and 16 tinidazole, in random order. The 2 groups were comparable. Both drugs were given orally in a single daily dose of 2g for a minimum of 3 days, with treatment extended if considered clinically advisable. 12 of 15 patients (80%) were cured with metronidazole given for an average period of 7 days (range 4 to 14 days). 15 of 16 patients (93.8%) given tinidazole were cured and the mean duration of treatment was 4 days (range 3 to 6 days). There were fewer side-effects with tinidazole. In this study of hepatic amoebiasis in Bangladesh, tinidazole was found to be superior to metronidazole in overall efficacy because a shorter course of treatment was necessary and it caused fewer side-effects.

Adolescent↗