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Biomedical subjects

F Farzaneh

Publications and source records attributed to F Farzaneh.

At least 19 recordsLinked to original sources
PubMed1995

Quantitative multiwell myeloid differentiation assay using dichlorodihydrofluorescein diacetate (H2DCF-DA) or dihydrorhodamine 123 (H2R123).

It is well established that the fluorescent probes dichlorodihydrofluorescein diacetate (H2DCF-DA) and dihydrorhodamine 123 (H2R123) can be used to detect the respiratory burst response of mature myeloid cells. We describe a simple, fast and quantitative assay for myeloid differentiation based on the oxidation of these probes, which can be performed from start to finish in 96-well dishes. A bis(acetoxymethyl) ester of H2DCF-DA, 5-(and-6)-carboxy-2',7'-dichlorodihydrofluorescein diacetate (CODCF-DA) is also capable of detecting the respiratory burst, but is less suitable than H2DCF-DA or H2R123 in our system. The amount of fluorescence produced can be quantified using a calibration curve, and values can be normalised to cell numbers using the 3-(4,5-dimethylthiazol-2-yl)2,5-diphenylte-trazolium bromide (MTT) cell proliferation assay. Results are expressed as 'equivalents of soluble fluorescein' (ESF) produced per cell under the defined reaction conditions. The extent to which HL60 cells reduce MTT is unaffected by differentiation induced by retinoic acid or 1 alpha,25-dihydroxyvitamin D3, and normalisation of fluorescence values using the MTT assay appears to be valid for a wide range of myeloid cell lines and differentiation inducers or cytokines.

Calibration↗
PubMed1995

Genomic variations in the hepatitis B core gene: a possible factor influencing response to interferon alfa treatment.

BACKGROUND/AIMS: Interferon treatment causes a sustained loss of virus replication only in a proportion of patients with chronic hepatitis B. This study investigated whether genomic variations in the precore/core gene of hepatitis B virus affect the response to interferon alfa. METHODS: The precore/core region was sequenced in 46 serum samples obtained before, during, and after interferon treatment of 12 patients. RESULTS: In 23 samples from 7 responders (group A), there were 24 missense mutations, whereas in 23 samples from 5 patients who did not respond or relapsed after treatment (group B), there were 141 missense mutations (P < 0.001). All group B patients had cirrhosis, but only 2 of 7 patients in group A had cirrhosis (P = 0.026). Substitutions in amino acids 21-27 of the core protein, known to diminish HLA-A2-restricted cytotoxic T-cell function, were found in all nonresponders but in none of the responders. No significant changes occurred in the precore/core region in responders after seroconversion to antibody to hepatitis B e antigen, but multiple variations persisted in group B during treatment and new mutations appeared with the relapse of hepatitis. CONCLUSIONS: Specific mutations in the core protein that can interfere with T-cell function occur frequently in patients with advanced chronic hepatitis B and may affect the response to interferon.

Adult↗
PubMed1995

Ovarian tumour antigens as potential targets for immune gene therapy.

Major new developments in the understanding of the molecular mechanisms involved in immune recognition of self, and immune mediated rejection of foreign antigens, have resulted in the development of a variety of novel therapeutic strategies for the treatment of cancer. Cornerstones of the advances in this area have been the identification of tumour antigens and demonstration of immune recognition of neoplastic cells, most notably in malignant melanoma. There are now a number of clinical immune gene therapy trials in progress for the treatment of cancer by stimulating immune mediated rejection of malignant cells. Here we examine the evidence for immune recognition of ovarian tumour cells and the presence of putative ovarian tumour antigens as potential targets for immune gene therapy of ovarian carcinoma.

Antigen-Presenting Cells↗
PubMed1994

Association of ovarian malignancy with expression of platelet-derived endothelial cell growth factor.

BACKGROUND: At the present time, the pathogenesis of ovarian cancer remains poorly understood, with invasive diagnosis and ineffective treatment for women with the disease. Despite scientific and medical advances in oncology, the overall 5-year survival rate of 30% for ovarian cancer patients has not changed in 20 years. An understanding of the angiogenic process as it occurs in ovarian cancer would not only increase our knowledge of the pathogenesis of this cancer but also might offer novel opportunities for therapeutic intervention. PURPOSE: Our aim was to study the expression of messenger RNA (mRNA) coding for four putative angiogenic factors in normal ovaries and benign and malignant ovarian tumors: platelet-derived endothelial cell growth factor (thymidine phosphorylase), vascular endothelial growth factor, basic fibroblast growth factor, and transforming growth factor-beta 1. METHODS: Four normal ovaries and 25 tumors (seven benign, one of borderline malignancy, and 17 malignant) were collected from 29 patients during elective oophorectomy. The site of sampling (areas of high-velocity blood flow) was directed by transvaginal color Doppler imaging performed within 24 hours of the surgery. Increased blood flow within the tissues was demonstrated by the presence of color (i.e., the velocity was > 7 cm/s) and, together with a pulsatile index of less than 1.0, constituted a positive scanning result. In scan-positive tissues, the area of maximum blood flow was chosen. In scan-negative tissues, a solid area was chosen in complex lesions, or the cyst wall was chosen in simple lesions. Ovarian RNA was subsequently extracted from areas of high-velocity flow (i.e., tissues with a positive scanning result) or from solid areas or septa in tissues with a negative scanning result. A ribonuclease protection assay was used to assess the expression of mRNA coding for the four angiogenic factors. RESULTS: Two normal ovaries (containing a corpus luteum) and one benign and 17 malignant tumors (plus the borderline) gave a positive scanning result. There was a significant difference between the expression of mRNA for platelet-derived endothelial cell growth factor between scan-positive and scan-negative tissues (P < .001) and between benign and malignant tumors (P < .001). CONCLUSIONS: Areas of high blood velocity in ovarian tumors are associated with increased expression of platelet-derived endothelial cell growth factor. IMPLICATIONS: Drugs that affect the angiogenic activity of platelet-derived endothelial cell growth factor offer a potential route for therapeutic intervention.

Autoradiography↗
PubMed1994

Hepatic expression of hepatocyte-growth-factor-like/macrophage-stimulating protein mRNA in fulminant hepatic failure.

We investigated whether impaired Kupffer cell phagocytosis in fulminant hepatic failure could be due to reduced synthesis of hepatocyte-growth-factor-like/macrophage-stimulating protein (HGFL/MSP), a serum protein synthesised predominantly in hepatocytes and required by tissue macrophages for phagocytosis. Hepatic expression of the 3.0 kb HGFL/MSP mRNA, assessed by northern hybridisation, was lower in nine patients with fulminant hepatic failure undergoing liver transplantation than in three liver grafts as controls (median absorbance units 97 [range 15-1200] versus 1114 [1100-1120], respectively; p < 0.05). Decreased hepatic HGFL/MSP production might cause impaired Kupffer cell phagocytosis in fulminant hepatic failure.

Adult↗
PubMed1994

Differences in immune recognition of cytochrome P4502D6 by liver kidney microsomal (LKM) antibody in autoimmune hepatitis and chronic hepatitis C virus infection.

LKM-1 antibody, which characterizes a subtype of autoimmune hepatitis (AIH), is also found in some patients with chronic hepatitis C virus (HCV) infection. It has been suggested that HCV initiates autoimmunity through molecular mimicry, because there is partial identity between HCV and cytochrome P4502D6 (CYP2D6), the putative target of LKM-1. Whether CYP2D6 is the target of LKM-1 in HCV-related liver disease, however, is controversial. To clarify this issue, we have studied by phage plaque assay and Western blot the reactivity to recombinant CYP2D6, isolated from a human liver cDNA library, in 55 patients with LKM-1, 18 (14 females, median age 12 years) anti-HCV-negative, with classical AIH, and 37 (27 females, median age 52 years) anti-HCV-positive. Reactivity to CYP2D6 was found in 72% of the anti-HCV-negative, but only in 27% of the anti-HCV-positive patients (P < 0.001), although immunofluorescence LKM-1 titres were similar in the two groups. In addition, to investigate whether the antibody responsible for the LKM-1 fluorescent pattern also reacts with CYP2D6, we have determined the specificity of LKM-1 antibodies present in the supernatant of lymphoblastoid B cell lines obtained from two patients with LKM-1-positive AIH. An oligo/monoclonal antibody thus generated gave both the typical fluorescent pattern and reacted with CYP2D6. Our results show that whilst antibodies producing the characteristic LKM-1 fluorescent pattern can react with CYP2D6, not all LKM-1-positive sera do so, particularly if obtained from patients with chronic HCV infection. This suggests that LKM-1 in HCV infection recognizes epitopes or antigens different from those targeted in AIH.

Adolescent↗
PubMed1994

The PML-RAR alpha gene product of the t(15;17) translocation inhibits retinoic acid-induced granulocytic differentiation and mediated transactivation in human myeloid cells.

Acute promyelocytic leukemia (APL) is characterized by an arrest of granulocytic differentiation and a reciprocal t(15;17) translocation fusing the PML gene to the retinoic acid receptor alpha (RAR alpha) gene. PML was recently identified as a potential transcription factor. In non hematopoietic cells, the transfected PML-RAR alpha product binds all trans retinoic acid and exhibits altered transactivating properties when compared with RAR alpha. A major question raised by these observations is whether PML-RAR alpha contributes to the inhibition of myeloid differentiation. We find that in myeloid cell lines responsive to retinoic acid, PML-RAR alpha blocks retinoic acid mediated transactivation and totally abrogates the retinoic acid mediated granulocytic differentiation. These findings strongly suggest that PML-RAR alpha may, by blocking normal retinoic acid dependent myeloid differentiation, participate in the leukemogenesis of APL. The fact that high doses of all-trans retinoic acid relieve the inhibitory effect of PML-RAR alpha corroborates the therapeutic effect of all-trans retinoic acid in APL patients.

Base Sequence↗
PubMed1993

Whole chromosome 17 loss in ovarian cancer.

Chromosomal deletions, associated with the loss of normal function of tumour suppressor genes, have been identified in a variety of both familial and sporadic human cancers. Although the molecular pathology of ovarian cancer is not understood, several studies have reported deletions in chromosome 17 in ovarian tumours. We have used 13 restriction site polymorphic, microsatellite, and variable number tandem repeat markers to make a detailed analysis of chromosome 17 deletions in 12 benign and 19 malignant ovarian tumours. Two benign and 11 malignant tumours were informative for at least one marker on each arm of the chromosome. Loss of heterozygosity (LOH) was detected in both arms (by all informative markers) in 5 malignant tumours from four women (three with the disease at FIGO stage Ia). In a further bilateral ovarian tumour a partial LOH affecting 17q22-q25 was present in one ovary only. By contrast to a number of previous studies, none of the 19 malignant and 12 benign tumours showed ERBB2 (17q12-22) amplification. The data presented show that the loss of a whole copy of chromosome 17 is a frequent and relatively early event in the development of some ovarian cancers. This suggests the possible involvement of multiple chromosome 17 loci in the pathogenesis of ovarian cancer. Equally plausible is that the loss of a whole chromosome copy could be the product of chromosomal instabilities induced by loss of the normal allele of tumour suppressors, such as TP53, located on this chromosome.

Adenofibroma↗
PubMed1993

Retinoid receptors and acute promyelocytic leukaemia.

While a great deal has been learned about APL over the last few years, many important questions remain unanswered. It has become clear that the PML/RAR-alpha fusion protein is expressed in most cases of APL, and this protein presumably contributes to leukaemia initiation and/or progression. PML/RAR-alpha appears to specifically block the further differentiation of myeloid progenitor cells, although the mechanism of its action is not known. It may inhibit the transcription of RAR- or PML-regulated genes, in which case expression must be restored in the presence of therapeutic RA concentrations. However, the possibility remains that PML/RAR-alpha may have a novel function. In order to elucidate the molecular pathogenesis of APL, several important questions remain to be answered. These include whether PML is a transcription factor; the identification of its target genes and response elements, and the role of PML/RAR-alpha and RA in their regulation. Also whether the expression of PML/RAR-alpha in bone marrow cells (either by itself or in combination with other oncogenes) alters their tumourigenicity or differentiation potential. It is also important to determine the function(s) of PLZF and PLZF/RAR-alpha, and determine whether other APL patients with mutations involving PML or RAR-alpha (but not both) respond to therapy with all-trans-RA. Finally, it is important both for the understanding of the molecular biology of APL and its therapy, to determine the effects of other regulatory factors involved in the control of myeloid cell differentiation such as granulocyte colony stimulation factor (G-CSF) and granulocyte macrophage colony stimulating factor (GM-CSF) on APL cells in vitro and in vivo, both at presentation and in the RA-resistant patients in relapse.

Animals↗
PubMed1991

T2-weighted spin-echo pulse sequence with variable repetition and echo times for reduction of MR image acquisition time.

Use of intraacquisition modification of pulse-sequence parameters to reduce acquisition time for conventional T2-weighted spin-echo images was evaluated. With this technique (variable-rate spin-echo pulse sequence), the repetition time and echo time (TR msec/TE msec) were reduced during imaging as a function of the phase-encoding view. To maintain T2-based contrast, TR and TE for the low-spatial-frequency views were left at their prescribed values (eg, 2,000/80). TR and TE for the high-spatial-frequency views were progressively reduced during imaging (eg, to 1,000/20). Acquisition time was reduced by as much as 25%. In one pulse sequence, the duration of multisection imaging nominally performed at TR 2,000 and with 256 phase-encoding views was reduced from 9 minutes 30 seconds to 6 minutes 30 seconds. In all sequences, edges and small structures were enhanced, and T2 contrast was somewhat decreased in high spatial frequencies. Filtering of the raw data before reconstruction can suppress these effects and provide a net increase in contrast-to-noise ratio.

Brain↗
PubMed1990

Analysis of T2 limitations and off-resonance effects on spatial resolution and artifacts in echo-planar imaging.

Several aspects of blipped echo-planar imaging (EPI) are treated mathematically. An expression relating the necessary readout gradient strength and sampling time to the spatial resolution and readout duration is derived. It is shown how the net spatial resolution may be limited by the object's T2 characteristics and B0 field homogeneity, irrespective of the number of sampled points. Additionally, off-resonance effects result in a loss of spatial resolution and image distortion to a considerably greater degree than in conventional two-dimensional Fourier transform imaging. The extent of these effects is directly related to the time required to acquire the data matrix, and is therefore amplified when EPI is implemented on a standard commercial whole-body system which because of limited gradient performance uses necessarily longer sampling durations. Specific hardware modifications to a standard commercial imager are considered to allow successful EPI implementation. EPI image characteristics are compared quantitatively with those of conventional methods.

Magnetic Resonance Imaging↗
PubMed1990

Real-time interactive magnetic resonance imaging.

We describe a system for performing interactive MRI in real time. Using a TR/TE 7.1/3.5 ms sequence, the operator may alter a scan parameter and observe the effects of the alteration on the image within a few hundred milliseconds. With this system, we can interactively control the oblique scan slice orientation and, using inversion pulses, the image contrast.

Fluoroscopy↗
PubMed1990

High-speed line scan MR angiography.

We describe a system which forms MR angiographic images at high speed. Multiple axial sections are imaged sequentially using a 2DFT GRASS sequence with TR/TE 50/15 ms, 64 phase encodings per image. Reconstruction and projection of each image are performed immediately (within 220 ms) after data for that image are acquired. The projection angiogram is constructed line by line as the scan progresses, thereby totally eliminating any additional time required for reconstruction and projection.

Blood Vessels↗
PubMed1990

DMSO and retinoic acid induce HL-60 differentiation by different but converging pathways.

The expression of c-myc and two calcium-binding proteins, MRP8 and MRP14, has been analyzed in wild-type and differentiation-resistant HL-60 variants. In HL-R5 cells, resistant to the induction of differentiation by retinoic acid but not DMSO, the characteristic c-myc down-regulation which is associated with HL-60 differentiation, as well as increased levels of MRP8 and MRP14, is detectable only after DMSO treatment. By contrast HL-D4 cells, which were selected for resistance to the induction of differentiation by DMSO alone, are actually resistant to both DMSO and retinoic acid. However, treatment of HL-D4 cells with DMSO results in a transient c-myc down-regulation in the absence of either growth arrest or induction of differentiation. Neither agent can induce an increase in the level of either MRP8 or MRP14 in HL-D4. The resistance of HL-D4 cells to DMSO and retinoic acid, and the different effects of these agents on c-myc RNA levels, despite their common effect on the expression of MRP8 and MRP14, suggest that the two agents act through different pathways which coverage before the onset of myeloid differentiation in HL-60 cells.

Cell Differentiation↗