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Biomedical subjects

R Reddy

Publications and source records attributed to R Reddy.

At least 271 records · Page 15Linked to original sources
PubMed1975

The primary nucleotide sequence of nuclear U-2 ribonucleic acid. The 5'-terminal portion of the molecule.

The nuclear U-2 RNA which is highly modified (Reddy, R., Ro Choi, T.S., Henning, D., Shibata, H., Choi, Y.C., and Busch H. (1972) J. Biol. Chem. 247, 7245-7250) contains 13 pseudouridylic acid residues, 10 2'-O-methylated nucleotides and two modified bases including N-2,2, 7-trimethyl guanylic acid in its 5'-terminal portion (69 nucleotides). With the determination of this sequence and its overlap with the 3' portion of the molecule (nucleotides 70 to 196), the over-all nucleotide sequence of this RNA is:(see article). The concentration of modified nucleotides in its 5' portion is greater than for any RNA sequenced thus far.

Base Sequence↗
PubMedDate not supplied

High resolution, short echo time sodium imaging of articular cartilage.

The sodium present in articular cartilage interacts with the negatively charged proteoglycan aggregates in the matrix of the cartilage. Sodium images of short echo time may be useful for detecting changes that occur in the proteoglycan content of the cartilage. Such changes are indicative of early osteoarthritic damage, for example. Using an asymmetric short echo technique, sodium images of high resolution and signal-to-noise ratio that demonstrate anatomic features of the cartilage are presented. These images were obtained with echo times as short as 1 msec, at an in-plane resolution of 39 microns by 117 microns and signal-to-noise ratios of up to 40:1.

Cartilage, Articular↗
PubMedDate not supplied

Proton T1rho-dispersion imaging of rodent brain at 1.9 T.

Detection of H2(17)O with proton T1rho-dispersion imaging holds promise as a means of quantifying metabolism and blood flow with MRI. However, this technique requires a priori knowledge of the intrinsic T1rho dispersion of tissue. To investigate these properties, we implemented a T1rho imaging sequence on a 1.9-T Signa GE scanner. A series of T1rho images for different locking frequencies and locking durations were obtained from rat brain in vivo and compared with 5% (wt/vol) gelatin phantoms containing different concentrations of (17)O ranging from .037% (natural abundance) to 2.0 atom%. Results revealed that, although there is considerable T1rho-dispersion in phantoms doped with H2(17)O, the T1rho of rat brain undergoes minimal dispersion for spin-locking frequencies between .2 and 1.5 kHz. A small degree of T1rho dispersion is present below .2 kHz, which we postulate arises from natural-abundance H2(17)O. Moreover, the signal-to-noise ratios of T1rho-weighted images are significantly better than comparable T2-weighted images, allowing for improved visualization of tissue contrast. We have also demonstrated the feasibility of proton T1rho-dispersion imaging for detecting intravenous H2(17)O on a live mouse brain. The potential application of this technique to study brain perfusion is discussed.

Animals↗
PubMedDate not supplied

Organization of spliceosomal U6 snRNA genes in the mouse genome.

U6 RNA is an abundant small nuclear RNA (snRNA) required for splicing of pre-mRNAs. In mammalian cells, the genes for U1 to U4 snRNAs consist of multigene families ranging from 10 to 100 copies of real genes per haploid genome, and are transcribed by RNA polymerase II. In contrast, results obtained in this study indicate that U6 RNA, which is transcribed by RNA polymerase II and III, may be coded for in mouse cells by only two genes. These two U6 genes are at least 9 kb apart from each other, and the flanking sequences are highly conserved, indicating that the organization of U6 genes is similar to that observed for other mammalian U-snRNA genes.

Animals↗
PubMedDate not supplied

Structural and functional similarities between MRP and RNase P.

RNase P, the enzyme response for 5'-end processing of tRNAs and 4.5S RNA, has been extensively characterized from E. coli. The RNA component of E. coli RNase P, without the protein, has the enzymatic activity and is the first true RNA enzyme to be characterized. RNase P and MRP are two distinct nuclear ribonucleoprotein (RNP) particles characterized in many eukaryotic cells including human, yeast and plant cells. There are many similarities between RNase P and MRP. These include: (1) sequence specific endonuclease activity; (2) homology at the primary and secondary structure levels; and (3) common proteins in both the RNPs. It is likely that RNase P and MRP originated from a common ancestor.

Base Sequence↗
PubMedDate not supplied

Bulky adducts detected by 32P-postlabeling in DNA modified by oxidative damage in vitro. Comparison with rat lung I-compounds.

Oxygen free radicals, such as the hydroxyl radical generated by interaction of Fe2+ and H2O2 (Fenton reaction), are produced in mammalian cells as a result of aerobic metabolism and under various pathological conditions and are known to elicit mutations and potentially other adverse effects by reacting with DNA bases. Several products thus formed have recently been characterized as hydroxylated derivatives of cytosine, thymine, adenine, and guanine and imidazole-ring-opened derivatives of adenine and guanine in DNA. As shown herein by 32P-postlabeling, incubation of DNA under Fenton reaction conditions led to additional products which, by virtue of resistance to nuclease P1 catalyzed 3'-dephosphorylation and chromatographic behavior, appeared to be bulky adducts rather than small polar, hydroxylated or ring-opened nucleotide derivatives. Two major and five minor DNA derivatives were measured after 32P-postlabeling and TLC mapping of DNA oxidized in vitro under conditions known to lead to formation of reactive oxygen species. Amounts of products formed depended on Fe2+ and H2O2 concentrations and increased in the presence of L-ascorbic acid. One of the two major products was also detected in lung DNA of rats where its amount increased with animal age. Thus, at least one I-compound appeared to have its origin in the interaction of DNA with reactive oxygen species.

Animals↗
PubMedDate not supplied

History of obstetric complications, family history, and CT scan findings in schizophrenic patients.

It has been proposed that obstetric complications (OCs) are more common in patients with nonfamilial schizophrenia, and associated with lateral ventricular enlargement in such patients. We examined the relations among OCs, family history of schizophrenia or bipolar mood disorder, and lateral ventricular size and cortical sulcal prominence in 44 schizophrenic patients. A history of OCs was not related to an absence of a family history of schizophrenia, ventricle-brain ratio, or cortical sulcal prominence. None of the CT findings was related to family history.

Adult↗
PubMedDate not supplied

Laparoscopically directed fine needle aspiration for the diagnosis of hepatocellular carcinoma: a safe and accurate technique.

Although ultrasonography and computerized tomography have been useful in the diagnosis of hepatocellular carcinoma, the extent of metastases and the presence of cirrhosis are not identified by these techniques before surgery. We studied 27 cases of presumptive hepatocellular carcinoma by means of laparoscopy and fine needle aspiration. Fine needle aspirates provided positive diagnoses of hepatocellular carcinoma in all patients. Laparoscopy complements imaging studies and allows selection of patients amenable to hepatic resection.

Biopsy, Needle↗
PubMedDate not supplied

Effects of haloperidol on antioxidant defense system enzymes in schizophrenia.

Dysregulation of free radical metabolism as reflected by abnormal erythrocyte activities of three critical enzymes of the antioxidant defense system (AODS), i.e. superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT), has been reported in schizophrenic patients. The present study examined the effects of haloperidol, a standard antipsychotic agent, on the AODS enzymes, using a within-subject, repeated-measures, on-off haloperidol treatment design. The mean drug free period was 40 days. At baseline, there were no significant differences for all three enzymes between patients and age and sex-matched normal volunteers. During the drug-free condition, SOD activity, but not GSH-Px and CAT activities, was significantly higher relative to normal control subjects. However, within-subjects both SOD and GSH-Px activities, but not CAT activity, were higher in the drug-free condition compared to the treatment condition. No significant correlation was observed between SOD activity and plasma haloperidol (or daily haloperidol dose) levels. Smoking status, as assessed by the cotinine level, was unrelated to enzyme activities. In addition, none of the major AODS enzymes showed significant differences between relapsed and clinically stable patients. These findings suggest that haloperidol may not have direct regulatory effect on AODS enzyme activities and that SOD and GSH-Px activities may change in response to other factors such as change in symptom severity.

Adult↗