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Biomedical subjects

A Yazdani

Publications and source records attributed to A Yazdani.

At least 19 recordsLinked to original sources
PubMed2003

Dermatoglyphics in patients with eczema, psoriasis and alopecia areata.

BACKGROUND/AIMS: The study of patterns of fingerprints is important in anthropology and medical genetics, chiefly because of their diagnostic usefulness. In the present work, we studied the frequencies of various types of skin ridges of the first phalanx in patients with eczema, psoriasis and alopecia areata. METHODS: In a double-blind case-control study, we determined the frequencies of fingerprints in 551 patients (240 cases with eczema, 164 cases with psoriasis and 147 cases with alopecia areata) as well as in general population of Hamadan City (control group: 188 males and 529 females). We compared the frequencies between various fingers, hands and sexes in all three case groups as well as between case groups and control group. RESULTS: The frequencies of various types of fingerprints are presented in some tables. The results showed that frequencies are not statistically different according to types of fingers, hands (left or right) and sexes as well. But they are significantly different in various case groups and between case groups and control group. CONCLUSIONS: We can conclude that frequencies of various patterns of skin ridges differ in eczema, psoriasis and alopecia areata from normal population.

Alopecia Areata↗
PubMed2002

Atomic scale imaging and spectroscopy of a CuO(2) plane at the surface of Bi(2)Sr(2)CaCu(2)O(8+delta).

We have used a scanning tunneling microscope to demonstrate that a single CuO2 plane can form a stable and atomically ordered layer at the surface of Bi(2)Sr(2)CaCu(2)O(8+delta). In contrast to previous studies on high-T(c) surfaces, the CuO2-terminated surface exhibits a strongly suppressed tunneling conductance at low voltages. We consider a number of different explanations for this phenomena and propose that it may be caused by how the orbital symmetry of the CuO2 plane's electronic states affects the tunneling process.

Journal Article↗
PubMed2002

Mapping the one-dimensional electronic States of nanotube peapod structures.

Arrays of C60 molecules nested inside single-walled nanotubes represent a class of nanoscale materials having tunable properties. We report electronic measurements of this system made with a scanning tunneling microscope and demonstrate that the encapsulated C60 molecules modify the local electronic structure of the nanotube. Our measurements and calculations also show that a periodic array of C60 molecules gives rise to a hybrid electronic band, which derives its character from both the nanotube states and the C60 molecular orbitals.

Journal Article↗
PubMed2001

Public-private partnership in tuberculosis control: experience in Hyderabad, India.

SETTING: Hyderabad, India. OBJECTIVE: To determine whether private practitioners and the government can collaborate with a nongovernmental intermediary to implement DOTS effectively. DESIGN: A non-profit hospital provided DOTS services to a population of 100000 for 3 years, then expanded coverage to 500000 in October 1998. A hospital physician visited all private practitioners, encouraged them to refer patients, and gave feedback on each patient referred. After diagnosis, patients received directly observed treatment free of charge at the trust hospital or at 30 conveniently located small hospitals operated by local private practitioners. No financial incentives were used to encourage physicians to refer patients or to provide treatment observation. Diagnosis, treatment, and case and outcome definitions were performed as per DOTS policies; medicines and laboratory reagents were provided by the government. RESULTS: All 244 allopathic and 114 non-allopathic physicians practising in the area agreed to participate; 59% referred at least one patient. Of 2244 persons referred, 969 (43%) had tuberculosis. Physicians had obtained chest radiographs on 80% of patients before referral for sputum microscopy. The detection rate increased from 50 to 200/100000 over the first 2-3 years of the project, and has increased gradually since expansion; 90% of new smear-positive patients and 77% of re-treatment patients were successfully treated. Compared with those treated at a neighbouring government DOTS centre, patients in this project paid less for diagnosis ($5 vs. $20) and treatment ($1 vs. $11), largely due to lower transport costs. CONCLUSIONS: Collaborative efforts between private practitioners and the government can achieve moderate-high rates of case detection and high rates of treatment success. Public-private services appeared to be more convenient to patients, who paid less for care and were less likely to miss work in order to participate in DOTS. Clearly defined roles and expectations and frequent communication are essential to success. An institution such as a non-profit hospital can serve as an effective intermediary between the government DOTS programme and private practitioners.

Adolescent↗
PubMed1999

Functional significance of a newly discovered neuropeptide, orphanin FQ, in rat gastrointestinal motility.

BACKGROUND & AIMS: Orphanin FQ (OFQ) is a recently discovered neuropeptide that structurally resembles an opioid peptide. However, the functional role of OFQ in rat gastrointestinal tract remains unknown. METHODS: We investigated the effects of OFQ on contractions of muscle strips obtained from different regions of the gastrointestinal tract. Immunohistochemical studies were performed on rat colonic tissue using OFQ antibody. RESULTS: OFQ (10(-9) to 10(-7) mol/L) caused significant contractions in the rat colon but not in the stomach or small intestine. Tetrodotoxin, veratridine, and long-term serosal application of benzalkonium chloride completely abolished OFQ-induced colonic contractions without affecting myogenic contractions in response to carbachol. OFQ-induced contractions were not affected by naloxone, atropine, phentolamine, propranolol, methysergide, substance P antagonist, vasoactive intestinal polypeptide antagonist, apamin, and NG-nitro-L-arginine methyl ester. OFQ (10(-9) to 10(-7) mol/L) significantly reduced muscle contractions and 3H-acetylcholine release in response to electrical field stimulation in both the stomach and small intestine but not in the colon. OFQ-immunopositive neuronal fibers were found in the colonic myenteric plexus. CONCLUSIONS: These studies indicate that the mechanisms and sites of action of OFQ are region specific. OFQ inhibits cholinergic transmission in the stomach and small intestine, whereas OFQ stimulates colonic contraction possibly by inhibiting an inhibitory neural pathway within the myenteric plexus.

Acetylcholine↗
PubMed1997

Probing the Local Effects of Magnetic Impurities on Superconductivity

The local effects of isolated magnetic adatoms on the electronic properties of the surface of a superconductor were studied with a low-temperature scanning tunneling microscope. Tunneling spectra obtained near magnetic adsorbates reveal the presence of excitations within the superconductor's energy gap that can be detected over a few atomic diameters around the impurity at the surface. These excitations are locally asymmetric with respect to tunneling of electrons and holes. A model calculation based on the Bogoliubov-de Gennes equations can be used to understand the details of the local tunneling spectra.

Journal Article↗
PubMed1996

Characterization and genomic mapping of genes and pseudogenes of a new human protein tyrosine phosphatase.

Previously described protein tyrosine phosphatases (PTPs) are classified into three types according to their sequence homology and structural features. Here we describe the characterization of genes and pseudogenes of a member of a fourth type of PTP, designated protein tyrosine phosphatase 4A (PTP4A). The 167-amino-acid human PTP4A bears the signature active site of all PTPs, but does not show any other sequence homology to any of the previously described PTPs. Two cDNAs encoding PTP4A that differed in their noncoding regions were isolated. Another cDNA that has a high level of sequence identity with these two cDNAs and a deletion in the coding region was also isolated. Northern analysis using a probe from a common 3'-untranslated region of the cDNAs recognized mRNAs of about 2 and 4 kb. Both species of mRNA were seen in all human adult and fetal tissues tested. Fluorescence in situ hybridization mapping of the corresponding yeast artificial chromosome clones and sequence-tagged site analysis suggested that one of the PTP4A coding genes is located at 1p35 and the other is on chromosome 11. A processed pseudogene for PTP4A was found in the BRCA1 region of 17q21 and shares 96% sequence identity to one of the PTP4A coding cDNAs. Our studies also suggest the existence of another processed pseudogene on chromosome 11.

Adult↗
PubMed1996

Off-Resonance Conduction Through Atomic Wires

The electrical resistance of wires consisting of either a single xenon atom or two xenon atoms in series was measured and calculated on the basis of an atom-jellium model. Both the measurement and the calculation yielded a resistance of 10(5) ohms for the single-xenon atom system and 10(7) ohms for the two-xenon atom system. These resistances greatly exceeded the 12,900-ohm resistance of an ideal one-dimensional conduction channel because conduction through the xenon atoms occurs through the tail of the xenon 6s resonance, which lies far above the Fermi level. This conduction process in an atom-sized system can now be understood in terms of the electronic states of individual atoms.

Journal Article↗
PubMed1996

Molecular dissection of a cosmid from a gene-rich region in 17q21 and characterization of a candidate gene for alpha-N-acetylglucosaminidase with two cDNA isoforms.

A cosmid mapped to human Chromosome (Chr) 17q21, c140c10, was found to contain a CpG island. We completed the sequence analysis of c140c10 because of two considerations: the cosmid contained an STS from the 17-beta-hydroxysteroid dehydrogenase gene (17-HSD), which was believed to be a neighbor of the breast cancer susceptibility gene, BRCA1; CpG islands are usually associated downstream and/or upstream of human genes. Computer-based exon trapping of the cosmid sequence revealed putative additional exons. With two of those exons used as a probe to screen human placental cDNA libraries, two cDNA isoforms for a novel gene, designated as ufHSD, were isolated. The amino acid sequence of the open reading frames of the cDNA showed no significant homology to any protein in the data base. However, it is possible that our cDNAs are from the gene for alpha-acetylglucosaminidase, which has recently been localized to the same region. Northern analyses show that the major isoform is expressed in all tissues tested, with the highest expression in blood leukocytes and lowest in brain. Finally, our study has shown that the 46.7-kb cosmid c140c10 encompasses loci for five genes and pseudo-genes: PsiPTP4A, ufHSD, 17-HSDI, 17-HSDII, and 22A1.

Acetylglucosaminidase↗
PubMed1995

Isolation of chromosome-specific genes by reciprocal probing of arrayed cDNA and cosmid libraries.

We have identified and mapped 61 novel and previously described chromosome 17 and X genes, using a human placental cDNA library. These genes were isolated using a gene identification and mapping strategy based on reciprocal probing of arrayed chromosome specific cosmid and cDNA libraries. This strategy scans gridded cosmids for nuclear genes and isolates the expressed sequence by a cosmid to cDNA filter hybridization. Inherent to this approach is the advantage of identifying the corresponding genomic cosmid clone of a particular cDNA. The genomic and cDNA reagents can be used for fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) based mapping to resolve map positions of cDNAs belonging to gene families and those associated with multiple chromosomes. The downstream utility of reagents generated by the reciprocal probing methods is demonstrated in our studies.

Base Sequence↗