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N Ahmadi

Publications and source records attributed to N Ahmadi.

12 recordsLinked to original sources
PubMed2001

Radioimmunoassay for N-terminal probrain natriuretic peptide in human plasma.

Measurement of plasma levels of natriuretic peptides has been used to assess left ventricular dysfunction and prognosis. Recently levels of the N-terminal peptide fragment of the precursor of brain natriuretic peptide have been reported to be present in peripheral plasma and to be increased in chronic heart failure patients. Our aim in this study was to develop a radioimmunoassay for N-terminal proBNP, to compare its plasma concentrations in control subjects and in patients with end-stage heart failure and to define its relation to brain natriuretic peptide (BNP). A polyclonal antibody was raised in rabbits against human N-terminal proBNP fragment (amino acid 1-21). The plasma N-terminal proBNP concentrations were assayed directly without extraction. No detectable cross-reactivity existed with other natriuretic peptides: BNP, ANP or N-terminal proANP. The assay had a detection limit (2 SD from zero) of 9.7 pmol/L. Plasma N-terminal proBNP was 29 (13-75) (median (range)) pmol/L in the control group. There were no gender difference, male: 28 (13-61) vs. female 33 (13-75) pmol/L, p= NS, but there was a positive correlation to age (r=0.52, p<0.0001). In patients with end-stage heart failure the median N-terminal proBNP levels were increased significantly 616 (114-2781) pmol/L (p<0.001) and in pooled data N-terminal proBNP showed a close correlation to BNP (r=0.96, p<0.0001). Size exclusion of plasma extracts indicated that proBNP (1-108) may circulate both as intact prohormone and as split products, N-terminal proBNP (1-76) and BNP (77-108). Our results support the concept that N-terminal proBNP measurement could be a valuable tool in the biochemical indication of increased cardiac wall stress.

Adult↗
PubMed2000

Class of integrable diffusion-reaction processes

We consider a process in which there are two types of particles, A and B, on an infinite one-dimensional lattice. The particles hop to their adjacent sites, like the totally asymmetric exclusion process (ASEP), and have also the following interactions: A+B-->B+B and B+A-->B+B, which all occur with equal rate. We study this process by imposing four boundary conditions on the ASEP master equation. It is shown that this model is integrable, in the sense that its N-particle S matrix is factorized into a product of two-particle S matrices and, more importantly, the two-particle S matrix satisfies the quantum Yang-Baxter equation. Using the coordinate Bethe-ansatz, the N-particle wave functions and the two-particle conditional probabilities are found exactly. Further, by imposing four reasonable physical conditions on two-species diffusion-reaction processes (where the most important ones are the equality of the reaction rates and the conservation of the number of particles in each reaction), we show that among the 4096 types of interactions which have these properties and can be modeled by a master equation and an appropriate set of boundary conditions, there are only 28 independent interactions which are integrable. We find all these interactions and also their corresponding wave functions. Some of these may be new solutions of the quantum Yang-Baxter equation.

Journal Article↗
PubMed1995

Stage- and lineage-specific expression of the HOXA10 homeobox gene in normal and leukemic hematopoietic cells.

There is growing evidence that the HOX homeobox-containing transcription factors are differentially expressed during hematopoiesis. We have previously demonstrated that the HOXA10 gene is expressed in unfractionated normal marrow and in immortalized leukemic cell lines with myelomonocytic features, but not in cell lines with lymphoid or erythroid features. To gain insights into the patterns of activation of this gene during hematopoietic differentiation, we have examined HOXA10 expression in CD34+ and CD34- subfractions of normal marrow and normal peripheral blood, as well as samples from patients with a variety of acute and chronic leukemias. HOXA10 is strongly expressed in CD34+ normal marrow cells, markedly downregulated in CD34- marrow cells, and inactive in mature neutrophils, monocytes, and lymphocytes. HOXA10 is expressed in all types of acute myelogenous leukemia (AML) with the notable exception of acute promyelocytic leukemia (AML-M3). HOXA10 message is observed in chronic myelogenous leukemia (CML) but appears to be reduced in accelerated phase and blast crisis, particularly lymphoid blast crisis. With rare exception, HOXA10 expression is not observed in samples of acute or chronic lymphoid leukemias. Normal marrow and patient samples appear to contain a single transcript which encodes a full-length homeobox-containing protein, while immortalized cell lines contain an additional alternatively spliced transcript. These studies indicate that HOXA10 expression is restricted to early stages of myeloid differentiation.

Base Sequence↗
PubMed1975

The effect of Systox on ionic fluxes in excised barley roots.

The influence of various concentrations of the thiol isomer of Systox on ionic fluxes in excised barley roots was investigated. For purposes of comparison, treatments with DNP alone, or in combination with the Systox isomer, were included. Rb and Cl absorption, regardless of the external salt concentrations, were progressively reduced as the Systox concentration in the external solution increased. Treatment with Systox did not result in any appreciable increase in the efflux rates of Rb or Cl ions. DNP treatment enhanced the efflux of Rb but not of Cl. The increased efflux was too small to account for the reduced net uptake. A comparison of individual and combined effects of Systox and DNP on ion absorption indicated an independent action of the two inhibitors.

Absorption↗
PubMed1975

The effect of systox on rubidium absorption by excised barley leaf tissue.

The influence of various concentrations of the thiol isomer of Systox on Rb absorption by excised barley leaf tissue was compared with the effect of DNP and DCMU. Rb absorption, regardless of the external salt concentration, was progressively reduced as the Systox concentration in the external solution was increased from 0.25 to 1.0 mM. Under anaerobic conditions, light-enhanced Rb absorption by leaf tissue was not influenced by Systox treatments. DNP treatment reduced ion absorption by leaf tissue. In the dark, the relative inhibitory effect of DNP and Systox treatment on Rb absorption was greater than in the light. The combination of Systox plus DNP inhibited Rb absorption more than did separate treatment with either compound. DCMU treatments in the light resulted in a reduction of light-enhanced Rb uptake. Also in the light, the combination of DCMU with Sytox, DNP, or both, inhibited Rb uptake more than did separate treatments of Systox, DNP, or Systox plus DNP. It is suggested that the inhibitory effect of Systox on Rb absorption by leaf tissue is due to partial inhibition of oxidative phosphorylation. Moreover, since light-enhanced Rb absorption is not affected by Systox, it is concluded that Systox has no effect either on the photophosphorylation reactions or on the utilization of high-energy phosphorylated compounds.

Absorption↗
PubMedDate not supplied

Effects of iodized salt consumption on goiter prevalence in Isfahan: the possible role of goitrogens.

OBJECTIVE: To evaluate the success of the Iranian Iodine Deficiency Disorders Committee in achieving World Health Organization (WHO) goals for reducing the prevalence of goiter in children by adding iodine to table salt beginning in 1989. METHODS: In 1997, 8,000 male and female 6- to 18-year-old students were selected by cluster sampling in schools of Isfahan. Their thyroids were examined by four endocrinologists, and goiter was staged on the basis of the WHO classification. As an index of iodine consumption, urinary iodine concentrations were measured in 3,000 students. RESULTS: Goiter was observed in 62% of the students. Of the overall study group, 94% had sufficient iodine consumption (urinary iodine concentration of 10.0 microg/dL or more). Of those students who had sufficient iodine intake, 63.2% had goiter. Of the 6% of students with iodine deficiency, 5% had mild, 0.9% had moderate, and only 0.1% had severe iodine deficiency. Goiter was absent in half of the students with severe iodine deficiency. The prevalence of goiter in 6- to 10-year-old children was 65%. CONCLUSION: Despite sufficient iodine intake, the prevalence of goiter is still high in Isfahan City. Apparently, either this high prevalence has no relationship to iodine deficiency and possibly other unknown goitrogens are involved in the pathogenesis of goiter in Isfahan or the period of iodine intake has been too brief to affect thyroid sizes. Inasmuch as goiter prevalence is also high in the 6- to 10-year-old children, who have had iodized salt available for most of their lives, the second option is less probable. Another possibility is an increased rate of autoimmune thyroid diseases (because of iodine repletion) that resemble goiter during their early stages.

Adolescent↗