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Biomedical subjects

A Karimi

Publications and source records attributed to A Karimi.

At least 19 recordsLinked to original sources
PubMed2003

Dnase1l3 deficiency in lupus-prone MRL and NZB/W F1 mice.

Loss of deoxyribonuclease I (Dnase1) function is associated with systemic lupus erythematosus (SLE) in humans and mice; however, no coding mutations in Dnase1 are found in polygenic murine models. Instead, both MRL-lpr strains and NZB/W F1 hybrids are homozygous for T89I missense in the macrophage-DNASE, desoxyribonuclease I-like 3 (Dnase1l3). By in vitro expression studies, this substitution decreases this enzyme's nuclease activity against free DNA by only approximately twofold; however, the mutation has a greater effect on the capacity of media conditioned with Dnase1l3 to confer a barrier to liposomal gene transfection to HeLa cells. The 89I substitution decreases the Dnase1l3 barrier function in vitro by eightfold (P < 0.01). In splenocytes and BM-derived macrophages of SLE mice, while cellular Dnase1l3 levels are induced relative to C57BL/6 (control) mice, levels of FD-nuclease activity are similar. Finally, media conditioned by MRL and NZB/W F1 macrophages, relative to control, contains a weak interferon-gamma (IFN-gamma) inducible Dnase1l3-associated barrier to transfection. This barrier function is hypothesized to reflect the inability of SLE mice to degrade membrane-enveloped DNA-associated antigens, such as apoptotic bodies, which are predicted to stimulate the characteristic autoimmunity of SLE. Our results for these two generally independent models strongly suggest that Dnase1l3 deficiency increases the susceptibility of these mice to polygenic SLE.

Animals↗
PubMed2003

Prevalence of Ureaplasma urealyticum and Mycoplasma genitalium in men with non-gonococcal urethritis.

This study in Teheran, Islamic Republic of Iran, investigated the prevalence of Ureaplasma urealyticum and Mycoplasma species in men with non-gonococcal urethritis. Urethral swab samples were collected from 125 cases and 125 healthy men as a control group. The samples were then investigated by culture methods. The rates of detected bacteria in case and control groups were 19.2% and 7.2% for U. urealyticum, 7.2% and 0.8% for M. genitalium, and 2.4% and 1.6% for M. hominis respectively. Statistical analysis showed a significant difference between case and control groups in the prevalence of U. urealyticum and M. genitalium but not M. hominis. It is concluded that in men, U. urealyticum and M. genitalium may have an etiologic role in non-gonococcal urethritis.

Adolescent↗
PubMed2001

In vitro effects of mycophenolic acid on the nucleotide pool and on the expression of adhesion molecules of human umbilical vein endothelial cells.

The immunosuppressive drug mycophenolate mofetil (MMF) and its active metabolite mycophenolic acid (MPA) selectively inhibit inosine 5'-monophosphate dehydrogenase (IMPDH), and therefore interfere with cellular guanine nucleotide biosynthesis. IMPDH is additionally involved in the synthesis of membrane glycoproteins, some of which are adhesion receptors known to play an active part in the regulation of cell-cell contacts, which are crucial in the process of recruitment and transendothelial infiltration of activated leucocytes in the transplanted organ. As a consequence, MPA leads to a reduction of cellular infiltrates in the course of transplant rejection. In the present study, the effects of MPA on human umbilical vein endothelial cells (HUVEC) are investigated at both molecular and cellular levels. In our experiments, HUVECs are treated with tumor necrosis factor-alpha (TNF-alpha; 10 ng/ml) in order to mimic activation occurring at a rejection crisis. The dose-dependent influence of concomitant incubation with MPA (5-20 micromol/l; 48 h, 37 degrees C, 5% CO2) on their intracellular nucleotide profile is observed by determining the concentrations of purine and pyrimidine nucleotides, using a HPLC method based on solvent generated ion-exchange. The possibility of synergistic effects is investigated by incubating endothelial cells with mixtures of three different immunosuppressants (mycophenolic acid; cyclosporin A, 100 ng/ml; prednisolone, 1 micromol/l)--a combination commonly used after transplantation--varying the amount of MPA (5-20 micromol/l). Stimulation with TNFalpha does not significantly modulate the intracellular levels of nucleotides quantitated. In the presence of MPA concentrations of at least 5 micromol/l, GTP levels (68+/-12%) are significantly decreased compared to controls (100%). At a concentration of 20 micromol/l MPA, the GTP amount is reduced to 58+/-7%. In contrast to these observations, the levels of UDP and UTP are increasing significantly under coincubation with MPA concentrations greater than 5 micromol/l. At 20 micromol/l MPA, UDP and UTP are increased to 147+/-19% and 114+/-11%, respectively. All other nucleotides (CTP, ADP, ATP) reveal no significant alterations in their intracellular concentrations under the conditions applied. Incubation of TNFalpha-treated HUVEC monolayers, with a mixture of three immunosuppressive drugs varying the amount of MPA, show no significant differences compared with the data observed after incubation with MPA alone. In addition, the influence of MPA (10 micromol/l) on a cellular level is observed by measuring the cell surface expression of adhesion molecules on cytokine-stimulated HUVECs, using TNFalpha (10 ng/ml), interferon-gamma (100 ng/ml), interleukin-1beta (10 ng/ml) and interleukin-8 (20 ng/ml). Expression of the intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), endothelial leucocyte adhesion molecule-1 (ELAM-1) and platelet endothelial cell adhesion molecule-1 (PECAM-1) was assessed by flow cytometry. Activation of endothelial cell monolayers with TNFalpha significantly increases the mean fluorescence intensity of VCAM-1 (361+/-14%) and ICAM-1 (429+/-47%) surface expression, compared to controls, and additionally induces E-selectin expression (2919+/-134%). The same tendencies, but in a lesser degree, are observed under stimulation of cells with either IFNgamma or IL-1beta. Incubation with a combination of TNFalpha and MPA leads to a significant reduction in VCAM-1 (329+/-13%) and E-selectin (2613+/-167%) expression, compared to the values obtained for HUVEC incubated with the cytokine alone. Treatment of the cells with IL-1beta/MPA also reduces the expression of VCAM-1 to a level significantly lower than the level observed after stimulation with IL-1beta. Incubation with MPA alone reveals no significant modulation in the expression of all surface molecules tested compared to the values of unstimulated HUVECs. The experiments show that the immunosuppressive action of MPA not only inhibits lymphocyte proliferation but also decreases the expression of adhesion molecules on endothelial cells, which are the first target of the cellular rejection process.

Cell Adhesion Molecules↗
PubMed2001

Intensive care management of head-injured patients in Europe: a survey from the European brain injury consortium.

OBJECTIVES: (a) to describe current practice in the monitoring and treatment of moderate and severe head injuries in Europe; (b) to report on intracranial pressure and cerebral perfusion pressure monitoring, occurrence of measured and reported intracranial hypertension, and complications related to this monitoring; (c) to investigate the relationship between the severity of injury, the frequency of monitoring and management, and outcome. METHODS: A three-page questionnaire comprising 60 items of information has been compiled by 67 centres in 12 European countries. Information was collected prospectively regarding all severe and moderate head injuries in adults (> 16 years) admitted to neurosurgery within 24 h of injury. A total of 1005 adult head injury cases were enrolled in the study from 1 February 1995 to 30 April 1995. The Glasgow Outcome Scale was administered at 6 months. RESULTS: Early surgery was performed in 346 cases (35%); arterial pressure was monitored invasively in 631 (68%), ICP in 346 (37%), and jugular bulb saturation in 173 (18%). Artificial ventilation was provided to 736 patients (78%). Intracranial hypertension was noted in 55% of patients in whom ICP was recorded, while it was suspected in only 12% of cases without ICP measurement. There were great differences in the use of ventilation and CPP monitoring among the centres. Mortality at 6 months was 31%. There was an association between an increased frequency of monitoring and intervention and an increased severity of injury; correspondingly, patients who more frequently underwent monitoring and ventilation had a less favourable outcome. CONCLUSIONS: In Europe there are great differences between centres in the frequency of CPP monitoring and ventilatory support applied to head-injured patients. ICP measurement disclosed a high rate of intracranial hypertension, which was not suspected in patients evaluated on a clinical basis alone. ICP monitoring was associated with a low rate of complications. Cases with severe neurological impairment, and with the worse outcome, were treated and monitored more intensively.

Adult↗
PubMed2000

Arginase activity in human breast cancer cell lines: N(omega)-hydroxy-L-arginine selectively inhibits cell proliferation and induces apoptosis in MDA-MB-468 cells.

L-Arginine is the common substrate for two enzymes, arginase and nitric oxide synthase (NOS). Arginase converts L-arginine to L-ornithine, which is the precursor of polyamines, which are essential components of cell proliferation. NOS converts L-arginine to produce NO, which inhibits proliferation of many cell lines. Various human breast cancer cell lines were initially screened for the presence of arginase and NOS. Two cell lines, BT-474 and MDA-MB-468, were found to have relatively high arginase activity and very low NOS activity. Another cell line, ZR-75-30, had the highest NOS activity and comparatively low arginase activity. The basal proliferation rates of MDA-MB-468 and BT-474 were found to be higher than the ZR-75-30 cell line. N-Hydroxy-L-arginine (NOHA), a stable intermediate product formed during conversion of L-arginine to NO, inhibited proliferation of the high arginase-expressing MDA-MB-468 cells and induced apoptosis after 48 h. NOHA arrested these cells in the S phase, increased the expression of p21, and reduced spermine content. These effects of NOHA were not observed in the ZR-75-30 cell line, which expresses high NOS and relatively low arginase. The effects of NOHA were antagonized in the presence of L-ornithine (500 microM), which suggests that in MDA-MB-468 cell line, the arginase pathway is very important for cell proliferation. Inhibition of the arginase pathway led to depletion of intracellular spermine and apoptosis as observed by terminal deoxynucleotidyl transferase (Tdt)-mediated nick end labeling assay and induction of caspase 3. In contrast, the ZR-75-30 cell line maintained its viability and its L-ornithine and spermine levels in the presence of NOHA. We conclude that NOHA has antiproliferative and apoptotic actions on arginase-expressing human breast cancer cells that are independent of NO.

Apoptosis↗
PubMed2000

The value of the "worst" computed tomographic scan in clinical studies of moderate and severe head injury. European Brain Injury Consortium.

OBJECTIVE: Computed tomographic (CT) scanning can reveal the pattern and severity of structural brain damage after head injury. With the proliferation of CT scanners in general hospitals, and with improvements in patient transport, the interval from injury to the first CT scan is decreasing. The potential result is an "admission" scan missing an evolving and potentially operable lesion. Furthermore, the literature is confusing regarding the timing and coding of CT findings. We sought to establish the frequency of deterioration in CT appearance from an admission scan to subsequent scans and the prognostic significance of such deterioration. METHODS: In a survey organized by the European Brain Injury Consortium, data on initial severity, management, and subsequent outcome were gathered prospectively for 1005 patients with moderate or severe head injury admitted to one of 67 European neurosurgical units during a 3-month period in 1995. The findings of the initial and the final ("worst") CT scan were classified according to the Traumatic Coma Data Bank system and were related to outcome as assessed using the Glasgow Outcome Scale 6 months after injury. RESULTS: Data on an initial and a final CT scan were available for 897 patients; of these, 724 patients were assessed using the Glasgow Outcome Scale at 6 months. The initial CT findings were classified as a diffuse injury for 53% of the cohort, with 16% of these diffuse injuries demonstrating deterioration on a subsequent scan. In 56 (74%) of 76 deteriorations, the change was from a diffuse injury to a mass lesion. When the initial CT scan demonstrated a diffuse injury without swelling or shift, evolution to a mass lesion was associated with a statistically significant increase in the risk of an unfavorable outcome (62% versus 38%). When the initial scan demonstrated evidence of swelling or shift, there was a nonsignificant trend in the opposite direction, although the numbers were limited. CONCLUSION: When an admission CT scan demonstrates evidence of a diffuse injury, follow-up scans should be performed, because approximately one in six such patients will demonstrate significant CT evolution. In studies comparing series of head-injured patients, correspondence of timing of CT scans is necessary for valid comparison.

Brain Injuries↗
PubMed1999

The European Brain Injury Consortium survey of head injuries.

To provide a picture of contemporary practice, a survey was carried out of severely and moderately head injured patients admitted to 67 'neuro' centres in 12 European countries. 1,005 adult head injuries were recruited over a three month period. Sixty items of information on demography, clinical features, investigations, management and early complications were captured on a simple, two-page questionnaire and, information on outcome at six months on a third page. The median age of the subjects was 38 years, 74% were male and 51% injured in road traffic accidents; 57% of patients were transferred to the 'neuro' centre from another hospital. Assessment of clinical responsiveness was limited by the use of sedation and intubation and information from four early time points (pre-hospital, arrival at the Accident and Emergency department, post-resuscitation, and arrival at the 'neuro' unit) was combined to stratify the subjects as severe (58%), moderate (17%) or intermediate (19%). In 48% of patients classified the CT scan showed features of a 'mass lesion' and in 40% showed a subarachnoid haemorrhage. Fifty-five centres provided the data on outcome for 94% of the cases recruited in these centres six months after injury. 31% died, 3% were vegetative, 16% severely disabled, 20% moderately disabled and 31% had made a good recovery. Comparison of the data from different parts of Europe showed differences in the frequency of secondary transfer, cause of injury, occurrence of major extracranial injury, CT scan findings, intracranial operation, clinical severity of injury and utilisation of the components of intensive care and the occurrence of a favourable outcome, although the latter difference was not statistically significant when variations in the initial severity of injury were taken into account. The findings in the present survey are compared with newly analysed information for three previous large series: the International Data Bank involving the UK, the Netherlands and the USA, the North American Traumatic Coma Data Bank, and data from four centres in the UK. The comparisons showed substantial similarities and also differences that may reflect variations in policy for admission of the head injury to 'neuro' units, and evolution in methods of assessment, investigation and management. The effects of these differences on outcome requires further, rigorous prospective study.

Adolescent↗
PubMed1999

Characterization of monomeric and dimeric B domain of Staphylococcal protein A.

Both monomeric and dimeric constructs of the B domain of protein A from Staphylococcus aureus have been characterized by NMR, CD and fluorescence spectroscopy. The monomeric form of the protein was synthesized using a novel method incorporating the use of a recombinant, folded, chimeric protein. A comparison of the recombinant monomeric form with the commercially available dimeric form indicates that, although the dimer retains the integrity of the three-helix bundle structure present in the monomer, there are interdomain contacts in the dimeric form. A single long-lived water molecule in the hydrophobic core of the three-helix bundle of monomeric protein A may represent an important stabilizing factor for the three-helix bundle topology.

Amino Acid Sequence↗
PubMed1999

The prevalence of coronary artery disease in an urban population in Isfahan, Iran.

OBJECTIVE: Cardiovascular diseases, especially coronary artery disease (CAD), are responsible for the highest mortality rate in Iran. This study was conducted to determine the prevalence of CAD in an urban sample in Isfahan by the Minnesota code of a 12-lead resting electrocardiogram (ECG), the Rose questionnaire on chest pain and a self-reported previous medical history. METHODS AND RESULTS: Among the target sample of 6,470 men and women aged 35-79 years who were randomly selected from 80 random clusters in Isfahan, 5,773 subjects (about 90%) have participated. The WHO (Rose) questionnaires (Q) on chest pain were completed for all participants and 12-lead ECGs were taken. The overall prevalence of CAD based on the Rose Q and/or ECG was 19.4% (95% CI 18.4% to 20.4%) which was significantly higher among women 21.9% (95% CI 20.5% to 23.3%) than men 16.0% (95% CI 14.5% to 17.5%) (p < 0.05). The prevalence of CAD increased with age in both sexes. The prevalence of definite and possible angina based on the questionnaire was higher among women compared to men (p < 0.05), also a greater prevalence of ECG-based possible ischaemia was observed among woman than men (12.3% vs. 7.5%) (p < 0.05). However, definite and possible MI and definite ischaemia based on ECG abnormalities were higher among men than women (p < 0.05). The total prevalence of symptomatic CAD was 9.3% and about 22% of those with symptoms of CAD on Q have some evidence on ECG. The findings also showed that CAD is more common among people with less education, lower income and the unemployed (p < 0.05). CONCLUSION: These findings indicate that there is a high prevalence of CAD among the Iranian population which need more programmes of health promotion and lifestyle changes and further studies to assess the used epidemiological methods for estimating CAD prevalence, especially among women.

Adult↗
PubMed1997

Review of functional magnetic resonance imaging in schizophrenia.

Functional magnetic resonance imaging (fMRI) holds great promise for assessing temporal changes in brain activity using various challenge paradigms. In this report, we review the 14 studies (eight of them abstracts) that comprise the fMRI literature available to date relating to schizophrenia. Twelve of the 14 investigations examined changes in blood-oxygen-level-dependent (BOLD) contrast: two examined blood volume. Eight of the 12 BOLD studies relied on lower-order cognitive processing to measure activation (involving sensory or motor areas), whereas four used higher-order tasks (word production, auditory processing, and subspan word recall involving multiple brain areas). Although the variability in tasks used, brain regions studied, imaging methods used, patient characteristics reported, and methods of reporting significance precluded a full meta-analysis, we re-analyzed these published data to compute effect sizes. In most studies, resting blood volume and BOLD changes, regardless of the complexity of the cognitive task, appeared to differ between patients with schizophrenia and control subjects.

Brain↗
PubMed1997

Absence of a stable intermediate on the folding pathway of protein A.

The B-domain of protein A has one of the simplest protein topologies, a three-helix bundle. Its folding has been studied as a model for elementary steps in the folding of larger proteins. Earlier studies suggested that folding might occur by way of a helical hairpin intermediate. Equilibrium hydrogen exchange measurements indicate that the C-terminal helical hairpin could be a potential folding intermediate. Kinetic refolding experiments were performed using stopped-flow circular dichroism and NMR hydrogen-deuterium exchange pulse labeling. Folding of the entire molecule is essentially complete within the 6 ms dead time of the quench-flow apparatus, indicating that the intermediate, if formed, progresses rapidly to the final folded state. Site-directed mutagenesis of the isoleucine residue at position 16 was used to generate a variant protein containing tryptophan (the 116 W mutant). The formation of the putative folding intermediate was expected to be favored in this mutant at the expense of the native folded form, due to predicted unfavorable steric interactions of the bulky tryptophan side chain in the folded state. The 116 W mutant refolds completely within the dead time of a stopped-flow fluorescence experiment. No partly folded intermediate could be detected by either kinetic or equilibrium measurements. Studies of peptide fragments suggest that the protein A sequence has an intrinsic propensity to form a helix II/helix III hairpin. However, its stability appears to be marginal (of the order of 1/2 kT) and it could not be an obligatory intermediate on a defined folding pathway. These results explicitly demonstrate that the protein A B domain folds extremely rapidly by an apparent two-state mechanism without formation of stable partly folded intermediates. Similar mechanisms may also be involved in the rapid folding of subdomains of larger proteins to form the compact molten globule intermediates that often accumulate during the folding process.

Amino Acid Sequence↗
PubMed1997

EBIC-guidelines for management of severe head injury in adults. European Brain Injury Consortium.

Guidelines for the management of severe head injury in adults as evolved by the European Brain Injury Consortium are presented and discussed. The importance of preventing and treating secondary insults is emphasized and the principles on which treatment is based are reviewed. Guidelines presented are of a pragmatic nature, based on consensus and expert opinion, covering the treatment from accident site to intensive care unit. Specific aspects pertaining to the conduct of clinical trials in head injury are highlighted. The adopted approach is further discussed in relation to other approaches to the development of guidelines, such as evidence based analysis.

Adult↗
PubMed1996

Exogenous infusion of adenosine depresses whole body O2 use in fetal/neonatal sheep.

To examine a possible metabolic regulatory role for adenosine, infusions of adenosine and adenosine deaminase were given to 11 near-term fetal sheep during the simulation of birth in utero. Fetal arterial blood gases, the concentration of a number of metabolites, insulin, and whole body O2 consumption (VO2) were measured. After intrauterine ventilation and cord occlusion, fetal/neonatal VO2, measured by closed-circuit respirometry, averaged 11.0 +/- 1.1 (SE) ml (STPD).min-1.kg fetal wt-1 and plasma adenosine concentration ([Ado]) was 1.29 +/- 0.21 microM. Infusion of adenosine (1.5 mumol.min-1.kg-1) during the next 30-min interval increased [Ado] to 1.57 +/- 0.28 microM (not significant) and decreased VO2 to 7.7 +/- 0.5 ml.min-1.kg-1 (P < 0.05). The infusion reduced systolic blood pressure by 19% (P < 0.01) and diastolic blood pressure by 25% (P < 0.01) and increased heart rate by 19% (P < 0.01). At the highest rate of adenosine infusion studied (6 mumol.min-1.kg-1), [Ado] increased to 4.27 +/- 0.46 microM (P < 0.001) and VO2 did not measurably decline further, although there were further decreases in blood pressure and increases in heart rate. After administration of adenosine deaminase, [Ado] decreased to 0.58 +/- 0.13 microM (P < 0.05), whereas VO2 increased to 11.2 +/- 0.8 ml.min-1.kg-1 (P < 0.05); blood pressure and heart rate returned to basal levels. The dependence of VO2 on [Ado] is described by the relationship VO2 = 6.14 + 4.89 exp(-0.45[Ado]) (n = 144; r = 0.34; P < 0.001). Throughout the experiment, arterial O2 content and plasma glucose, lactate, glycerol, and fatty acid concentrations were normal or elevated, and, therefore, O2 lack and substrate deficiency were unlikely to have caused the reduction in VO2. We conclude that plasma adenosine may act as a messenger of energy status for the ovine fetus/neonate and may contribute thereby to a maintenance of a balance between O2 supply and O2 demand.

Adenosine↗
PubMed1994

Prediction of cervical cerclage outcome by endovaginal ultrasonography.

OBJECTIVE: We hypothesized that shortened upper cervical segment length, measured by endovaginal ultrasonography, identifies patients with cervical cerclage at greater risk of preterm delivery. STUDY DESIGN: A total of 121 endovaginal ultrasonographic examinations were performed on 32 patients after cervical cerclage. Ultrasonographic measurements included length of the closed cervical canal segments above and below the cerclage and dilatation of the internal cervical os (funneling) with and without fundal pressure. The risk of preterm delivery was tested by Fisher's exact test (two-tailed). RESULTS: Development of funneling of the internal os and shortening of the upper cervical segment length were the most predictive of outcome in patients with cervical cerclage. Twelve patients had shortening of the upper cervical segment (< or = 10 mm) before 30 weeks' gestation (mean 22.6 +/- 2.7 weeks), whereas 20 patients continued to have upper cervical segment measurements > 10 mm. A short upper cervical segment before 30 weeks' gestation was associated with a significantly higher risk of preterm delivery before 36 weeks (58% vs 10%, p = 0.006) and before 34 weeks (50% vs 5%, p = 0.006). CONCLUSION: Endovaginal ultrasonographic assessment of the cervix in patients with cervical cerclage is a useful adjunct for predicting outcome and for counseling the patient.

Cervix Uteri↗
PubMed1993

Molecular dynamics analysis of a ribonuclease C-peptide analogue.

We have carried out a nanosecond molecular dynamics simulation of an analogue of the ribonuclease C-peptide in water. The overall conformation has an extended region for the first three amino acids connected to an alpha-helix for residues 4-13, and this basic structure is preserved throughout the simulation, with helical hydrogen bonds present 87% of the time, on average. The final helical hydrogen bond is spontaneously broken and re-formed several times, providing a detailed picture of such winding/unwinding events. The simulation was used to estimate the effects of internal motion on proton nuclear Overhauser effect spectroscopy (NOESY) intensities for several classes of important cross peaks. Within the helical regions, the effects of internal motion vary only a little from one residue to another for backbone-backbone cross peaks, and the relevant correlation functions reach plateau values within about 50 ps. The spectral simulations show, however, that it may be difficult to establish a close quantitative connection between NOESY cross-peak volumes and measures of helical content.

Amino Acid Sequence↗