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Biomedical subjects

Z Ali

Publications and source records attributed to Z Ali.

At least 37 records · Page 2Linked to original sources
PubMed2001

Iodide and bromide inhibit Ca(2+) uptake by cardiac sarcoplasmic reticulum.

Recent studies indicate that the Ca(2+) permeability of the sarcoplasmic reticulum (SR) can be affected by its anionic environment. Additionally, anions could directly modulate the SR Ca(2+) pump or the movement of compensatory charge across the SR membrane during Ca(2+) uptake or release. To examine the effect of anion substitution on cardiac SR Ca(2+) uptake, fluorometric Ca(2+) measurements and spectrophotometric ATPase assays were used. Ca(2+) uptake into SR vesicles was inhibited in a concentration-dependent manner when Br(-) or I(-) replaced extravesicular Cl(-) (when Br(-) completely replaced Cl(-), uptake velocity was approximately 70% of control; when I(-) completely replaced Cl(-), uptake velocity was approximately 39% of control). Replacement of Cl(-) with SO(2)(-4) had no effect on SR uptake. Although both I(-) and Br(-) inhibited net Ca(2+) uptake, neither anion directly inhibited the SR Ca(2+) pump nor did they increase the permeability of the SR membrane to Ca(2+). Our results support the hypothesis that an anionic current that occurs during SR Ca(2+) uptake is reduced by the substitution of Br(-) or I(-) for Cl(-).

Adenosine Triphosphate↗
PubMed2001

Role of conventional angiography in evaluation of patients with carotid artery stenosis demonstrated by Doppler ultrasound in general practice.

BACKGROUND AND PURPOSE: Previous studies have suggested that patients with carotid stenosis who are candidates for endarterectomy can be effectively identified on the basis of carotid Doppler ultrasound alone. Before widespread acceptance of this policy, the accuracy of carotid Doppler ultrasound outside selected centers and clinical trials needs to be evaluated. We performed a 12-month prospective study to evaluate the accuracy of Doppler ultrasound in identifying patients for carotid intervention in general practice settings. METHODS: Each patient referred to our endovascular service for diagnostic angiography to evaluate for carotid stenosis was interviewed and examined by a neurologist. Subjects consisted of symptomatic patients with >/=50% stenosis and asymptomatic patients with >/=60% stenosis by Doppler ultrasound. Information pertaining to demographic and cerebrovascular risk factors and the results of the carotid Doppler ultrasound were recorded. The severity of stenosis on angiograms was measured with North American Symptomatic Carotid Endarterectomy Trial criteria by a blinded observer. The results of both studies were compared to determine the relative accuracy of ultrasound results. RESULTS: Of 130 patients (mean age, 69+/-8.8 years) who met Doppler ultrasound criteria, 22 (17%) and 8 patients (6%) were found to have 30% to 49% or <30% stenosis by angiography, respectively. The positive predictive value of carotid Doppler ultrasound for identifying appropriate symptomatic candidates for carotid intervention (angiographic stenosis >/=50%) was 80%, with a false-positive value of 20%. The positive predictive value of carotid Doppler ultrasound for identifying appropriate asymptomatic candidates for carotid intervention (angiographic stenosis >/=60%) was 59%, with a false-positive value of 41%. Carotid endarterectomy or angioplasty and stent placement were undertaken subsequently in 60 (46%) of the patients. In 94 patients who underwent cerebral angiography alone, no complications were observed. CONCLUSIONS: The present accuracy of carotid Doppler ultrasound in general practice does not justify its use as the sole basis of selecting appropriate patients for carotid intervention. Given the relatively low rate of associated morbidity with present day techniques, additional confirmatory studies such as angiography should be performed in every patient before a decision regarding intervention is made.

Aged↗
PubMed2001

Fifty years of clinical examinations at the University of the West Indies.

The University of the West Indies was founded at Mona, Jamaica, in 1948. After fifty-two years, the format of the final Bachelor of Medicine clinical examination in Medicine and Therapeutics has been radically revised. The change from the traditional to an evidence-based, objective structured clinical examination (OSCE) was undertaken in November/December 2000. Assessment drives learning and both the methods chosen for assessment and the manner in which they are applied determine how students learn. The philosophical underpinnings of the change in format are discussed in this paper.

Clinical Competence↗
PubMed2001

Effect of pregnancy on plasma lipid concentration in Trinidadian women. Result of a pilot study.

In Trinidad and Tobago, cardiovascular disease and Type 2 diabetes mellitus are important causes of morbidity and mortality, and birth weight is significantly less than reference standards. Lower birth weight is associated with increased risk of these diseases. Variation in birth weight is due, in part, to deposition of adipose tissue in the foetus during the last trimester at the same time that maternal plasma triacylglycerol (TAG) increases. We conducted a pilot cross-sectional analysis of maternal plasma lipid status and birth weight in healthy, non-pregnant, primigravida Trinidadian women. Non-pregnant and pregnant women, in their second and third trimesters, and at term, were recruited at random from an antenatal clinic. Adult and umbilical cord plasma TAG, non-esterified fatty acids (NEFA) and phosphatidylcholine (PC) concentrations were determined from gas chromatographic analysis of fatty acids. Maternal height, weight, skinfold thickness and infant birth weight were measured. The infants born to Afro-Trinidadian and Indo-Trinidadian women were of low to normal birth weight (medians 3.07 and 3.22 kg, respectively). At term, plasma TAG concentration was approximately two fold (p < 0.05) greater than for non-pregnant women. The increment between 30-34 weeks was 1.5 to 1.9 fold lower than reported in other populations. There was a strong relationship (r = 0.8771, p = 0.019) between maternal and cord plasma TAG and NEFA, but not PC concentrations. There was no significant relationship between maternal TAG concentration at term and birth weight. The result suggests an impaired ability to increase plasma TAG concentrations during late gestation.

Adult↗
PubMed2000

Apparent confined placental mosaicism of trisomy 16 and multiple fetal anomalies: case report.

Trisomy 16 is frequently found confined to the placenta (confined placental mosaicism (CPM)), with a structurally normal fetus. In some cases of trisomy 16, the fetus has uniparental disomy for chromosome 16 (UPD16) which is associated with intrauterine growth restriction (IUGR) and fetal anomalies. We report a case of apparent confined placental mosaicism for trisomy 16, using standard cytogenetic techniques, but with multiple fetal abnormalities including congenital diaphragmatic hernia in which there was no evidence of UPD in the disomic tissues examined. Subsequent examination of fetal tissues using fluorescent in situ hybridization (FISH) demonstrated low levels of mosaicism for trisomy 16 in all the tissues examined. The use of FISH permits identification of mosaicism which conventional techniques may not identify.

Abnormalities, Multiple↗
PubMed2000

Tamoxifen inhibits Ca2+ uptake by the cardiac sarcoplasmic reticulum.

Ca2+ transients in isolated cardiac ventricular myocytes and the amount of Ca2+ that could be released from the sarcoplasmic reticulum (SR) in these cells by caffeine were reduced in the presence of tamoxifen. To examine the effects of tamoxifen on the cardiac muscle SR directly, isolated SR vesicles and fluorimetry methods were used to measure the uptake of Ca2+ by the SR and the ATPase activity of the SR Ca2+ pump. SR Ca2+ uptake was inhibited by tamoxifen at concentrations greater than 2.4 microM. Half-maximal inhibition was seen at approximately 5 microM. Inhibition of uptake was not due to the development of a substantial tamoxifen-dependent leak of Ca2+ from the SR or to a direct inhibitory effect of tamoxifen on the ATPase activity of the SR Ca2+ pump. In addition to its effect on SR Ca2+ uptake, tamoxifen also reduced the rate at which stored Ca2+ could be released from the SR by the Ca2+ ionophore 4-bromo A23187. Our results are consistent with the hypothesis that tamoxifen inhibits an ion current that accompanies Ca2+ movement across the SR membrane. This possibility is also consistent with the known inhibitory action of tamoxifen on some types of Cl- and K+ channels.

Animals↗
PubMed2000

Chemistry of Zataria multiflora (Lamiaceae).

The hexane soluble part of Zataria multiflora afforded three new aromatic constituents which include two p-cymene derivatives: multiflotriol (1), multiflorol (2) and an aromatic ester of p-hydroxy benzoic acid (3). In addition to these three new compounds, three known compounds, dihydroxyaromadendrane, luteolin and alpha-tocopherolquinone, have also been isolated for the first time from the same source. The structures of all the isolated constituents were elucidated by means of spectroscopic methods including 2D-NMR techniques.

Flavonoids↗
PubMed2000

Spatial mapping of the zone of secondary hyperalgesia reveals a gradual decline of pain with distance but sharp borders.

The purpose of this study was to examine how pain to punctate mechanical stimuli varies with position within the zone of secondary hyperalgesia. Secondary hyperalgesia was produced by an intradermal injection of capsaicin (50 microg) into the volar forearm of human volunteers (n=9). Before and at 20, 60 and 100 min after the capsaicin injection, a computer-controlled electromechanical stimulator was used to deliver controlled-force stimuli to the skin via a 12-mm wide, 100-microm thick blade probe. Three forces (16, 32 and 64 g; 1 s) were each applied in a random order to 10 sites spaced in 1-cm increments along a line starting 1 cm from the injection site and ending near the wrist. At 40 and 80 min after capsaicin injection the 'zone of hyperalgesia' was determined with use of a hand-held 20-g von Frey probe. Whereas, before capsaicin, the blade probe produced little or no pain, after capsaicin the 32-g and 64-g stimuli evoked pain consistently within but not outside the border of secondary hyperalgesia determined with the von Frey probe. Within the zone of hyperalgesia the average pain ratings to the 64-g stimulus decreased exponentially with distance from the injection site. Surprisingly, the space constant for this exponential decay was large (about 18 cm), and thus the decrease in pain ratings from the center to the edge of the secondary zone was small (37%). However, pain ratings dropped precipitously just outside the zone of secondary hyperalgesia. This finding unlikely reflects a ceiling effect because pain ratings within the zone of secondary hyperalgesia increased linearly with force. The relatively uniform pain ratings to the blade stimuli within the zone of secondary hyperalgesia and the sharp border that delimits the zone of hyperalgesia indicate that this sensory disturbance approaches being an 'all-or-nothing' phenomenon. Thus, a two-state model for central plasticity is needed to explain secondary hyperalgesia.

Adult↗
PubMed2000

Taraxacin, a new guaianolide from Taraxacum wallichii.

A new guaianolide, taraxacin (1), and a known sesquiterpene ketolactone (2) have been isolated from an ethyl acetate-soluble part of a methanolic extract of Taraxacum wallichii. The structure of 1 was established using NMR, MS, and X-ray crystallographic methods. The (13)C NMR data of 2 is also being reported for the first time.

Asteraceae↗
PubMed2000

Expression of cyclooxygenase-2 and nitrotyrosine in human gastric mucosa before and after Helicobacter pylori eradication.

To determine whether cure of Helicobacter pylori infection influences the expression of COX-2 and nitrotyrosine in the distal stomach of humans, biopsy specimens were examined immunohistochemically. H. pylori infection was determined using a rapid urease test, culture and histology. Positive staining of COX-2/nitrotyrosine in the epithelium was expressed as the percentage of stained cells to the total epithelial cells. There was a significant increase in COX-2/nitrotyrosine staining in H. pylori -positive subjects compared with H. pylori -negative subjects. Cure of the infection resulted in a significant decrease in both COX-2/nitrotyrosine staining in all patients (52.1+/-12.1% vs 15. 4+/-7.2%, P<0.001; and 57.3+/-13.6% vs 36.1+/-18.0%, P<0.01, respectively). However, immunoreactivity of COX-2/nitrotyrosine was observed in all cases with intestinal metaplasia even after the cure of H. pylori infection.Thus, cure of H. pylori infection may decrease the risk of gastric carcinogenesis due to COX-2 and NO-related compounds in gastric mucosa but not in those patients with intestinal metaplasia.

Adult↗
PubMed2000

Adenosine deaminase activity and lysozyme levels in children with tuberculosis.

Serum adenosine deaminase (ADA) activity and lysozyme levels were measured in 51 patients with tuberculosis (21 pulmonary, 15 miliary, 11 neurotuberculoma and four abdominal plus osteoarticular) and 20 healthy controls. The mean serum ADA activity and lysozyme levels were significantly raised in children with different forms of tuberculosis in comparison with controls (p < 0.001). The neurotuberculoma cases had the lowest mean enzyme levels and the differences were significant when compared with other forms of tuberculosis. The cut-off serum ADA activity of > or = 42 IU/l and lysozyme level of > or = 20 U/l were diagnostic of tuberculosis with 100 per cent sensitivity. A significant correlation was observed between the two parameters (r = 0.66; p < 0.001). Thus, with compatible clinical presentation, the raised serum level of either ADA or lysozyme can be used as a supportive diagnostic test.

Adenosine Deaminase↗
PubMed2000

Lysozyme levels for the diagnosis of tuberculous effusions in children.

Lysozyme level was measured in the fluid and serum of 42 tuberculous (25 pleural, 11 ascites and 6 pericardial) and 29 non-tuberculous (5 malignant, 9 empyema thoracis, 10 transudative ascites and 5 pyopericardium) effusions. The mean fluid lysozyme level was significantly raised in tuberculous pleural, ascites, and pericardial effusions in comparison to malignant pleural (p <0.001), transudative ascites (p < 0.001), and pyopericardium (p < 0.02) cases, respectively. The mean fluid/serum lysozyme ratio did not differ significantly between tuberculous and their corresponding non-tuberculous effusions. The confirmed tuberculous pleural effusion patients had significantly higher mean fluid lysozyme level and fluid/serum lysozyme ratio when compared with clinical cases (p < 0.05). The cut-off fluid lysozyme level of > or = 50/UI(-1) and fluid/serum lysozyme ratio of > or = 1.1 were considered for the diagnosis of tuberculous effusions; the sensitivity and specificity of fluid lysozyme and fluid/serum lysozyme ratios were 100, 100 per cent, and 97.6, 33.3 per cent, respectively, on excluding the patients with purulent effusions. A significant correlation was observed between the fluid and serum lysozyme levels in tuberculous effusions (r = 0.39,p < 0.01). Thus, fluid lysozyme was found to be a better and reliable test than fluid/serum lysozyme ratio for the diagnosis of tuberculous effusions in children.

Adolescent↗
PubMed2000

Novel cycloartane saponins from Corchorus depressus L.

Two novel bidesmosidic cycloartane-type glycosides, depressosides C and D were isolated from Corchorus depressus L. Their structures were elucidated as (22R)-16beta,22-epoxy-3beta,26-dihydroxy-9,19-cyclolanost-++ +24E-ene 3, 26-di-O-beta-D-glucopyranoside and (22R,24S)-22,25-epoxy-3beta,16beta,24-trihydroxy-9,19-cyclolano stane 3, 24-di-O-beta-glucopyranoside, respectively on the basis of chemical evidence and detailed spectroscopic studies.

Chromatography, Ion Exchange↗
PubMed2000

Intraarterial recombinant tissue plasminogen activator for ischemic stroke: an accelerating dosing regimen.

OBJECTIVE: Urokinase has been conventionally used for intraarterial thrombolysis in acute ischemic stroke. Recently, due to the withdrawal of urokinase from the market, attention has been focused on recombinant tissue plasminogen activator (r-tPA) for intraarterial administration. Data is limited regarding the intraarterial dose, efficacy, and safety profile of this agent. METHODS: We prospectively studied 8 consecutive patients with acute ischemic stroke who were referred for intraarterial lysis. Each patient was considered by the treating neurologist to be a poor candidate for intravenous therapy. We administered a maximum total dose of 40 mg of r-tPA intraarterially via superselective catheterization. Angiograms were obtained after each 10 mg of r-tPA, and responses were graded using modified Thrombolysis in Myocardial Infarction (TIMI) criteria for perfusion and degree of thrombus. RESULTS: Initial National Institutes of Health Stroke Scale (NIHSS) scores ranged from 16 to 21. Intervals from presentation to treatment initiation ranged from 1 to 8 hours. After administration of r-tPA, neurological improvement (decrease in NIHSS score > or =2) was observed in 4 patients. Mean perfusion grade improved from a pretreatment score of 0 with increasing doses of r-tPA to 1.1 +/- 1.0 with 10 mg, 1.5 +/- 1.4 with 20 mg, 2.0 +/- 0.8 with 30 mg, and 2.7 +/- 1.0 with 40 mg. Mean thrombus degree decreased from a pretreatment score of 4 with increasing doses of r-tPA to 2.8 +/- 1.2 after 10 mg, 2.6 +/- 1.4 after 20 mg, 1.9 +/- 1.5 after 30 mg, and 1.4 +/- 1.5 after 40 mg. Asymptomatic intraparenchymal hemorrhage was observed on CT scan in 2 patients at 24 hours. CONCLUSION: Our study suggests that intraarterial r-tPA in doses up to 40 mg is relatively safe. The dose appears to facilitate the recanalization process by lysis of local thrombus and improvement in distal flow.

Adolescent↗
PubMed1999

Steroidal saponins from Asparagus dumosus.

A new steroidal saponin, dumoside, characterized as (20S)-3 beta, 16 beta-dihydroxy pregn-5-ene-22-carboxylic acid (22, 16)-lactone-3-O-beta-chacotrioside, was isolated from the whole plant of Asparagus dumosus Baker and the structure was deduced from spectral data. In addition to dumoside three more steroidal saponins characterized as 3 beta-dihydroxy pregn-5,16-dien-20-one 3-O-beta-chacotrioside, 3 beta, 22 alpha, 26-trihydroxyfurost-5-ene-3-O-beta-chacotrioside-26-O- beta-D-glucopyranoside and its corresponding 22 alpha-O methoxy analogue were also isolated for the first time from this source. The structures have been identified with the help of FAB-MS, 1H NMR, 13C NMR and extensive 2D NMR spectroscopy, as well as comparison with reported spectroscopic data.

Carbohydrate Conformation↗
PubMed1999

Bucharioside and buchariol from Salvia bucharica.

A new monoterpene-glycoside (2-exo-beta-D-glucopyranosyl-1,8-cineol) named bucharioside from the methanol-soluble part and a new sesquiterpenoid (4,10-epoxy-6alpha-hydroxyguaiane) named buchariol from the hexane-soluble part of Salvia bucharica were obtained. Their structures were elucidated with the help of NMR spectroscopy including 1D and 2D experiments.

Cyclohexane Monoterpenes↗