Biomedical subjects

R Reddy

Publications and source records attributed to R Reddy.

At least 91 records · Page 5Linked to original sources

PubMed1998

Reduced status of plasma total antioxidant capacity in schizophrenia.

To examine whether antioxidant capacity is reduced in patients with schizophrenia, we determined plasma total antioxidant status (TAS) by quenching the absorbance of the radical cation formed by the reaction of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) with a metmyoglobin and hydrogen peroxide. TAS serves as an index of net antioxidant activity derived from various antioxidants in plasma. Male schizophrenic patients were compared with age- and sex-matched healthy control subjects, using a within-subject, repeated measures, on-off-on haloperidol treatment design. Drug-free patients were free of all psychotropic medications for an average of 32 days. Plasma TAS was significantly lower in patients with schizophrenia than in normal controls. Plasma TAS in patients was significantly and inversely correlated with symptom severity during the drug-free condition. There were no significant differences between on and off haloperidol-treatment conditions. When patients returned to haloperidol treatment after relapse, the plasma TAS remained fairly constant and was not significantly different from the same individuals during haloperidol-stabilization or drug-free periods. These findings are indicative of an impaired antioxidant defense system, not attributable to neuroleptic treatment, and lend further support to the notion that oxidative stress may have a pathophysiological role in schizophrenia.

Adult↗

PubMed1998

Adenylation of small RNAs in human cells. Development of a cell-free system for accurate adenylation on the 3'-end of human signal recognition particle RNA.

The 3'-end sequences of several human small RNAs were determined, and the results show that a fraction of human cytoplasmic 7SL, ribosomal 5S, and nuclear U2, U6, and 7SK small RNAs contain a post-transcriptionally added adenylic acid residue on their 3'-ends. Incubation of HeLa cell extract in vitro in the presence of [alpha-32P]ATP resulted in labeling of several small RNAs including ribosomal 5S and cytoplasmic 7SL as well as U2 and U6 small nuclear RNAs. Analysis of 7SL RNA labeled in this in vitro adenylation system showed that a single adenylic acid residue is added to the 3'-end. These results show that the adenylation observed in the in vitro system reflects the post-transcriptional adenylation occurring in vivo.

Adenosine Triphosphate↗

PubMed1998

Small RNA database.

The small RNA database is a compilation of all the small size RNA sequences available to date, including nuclear, nucleolar, cytoplasmic and mitochondria small RNAs from eukaryotic organisms and small RNAs from prokaryotic cells as well as viruses. Currently, approximately 600 small RNA sequences are in our database. It also gives the sources of individual RNAs and their GenBank accession numbers. The small RNA database can be accessed through the WWW (World Wide Web). Our WWW URL address is: http://mbcr.bcm.tmc. edu/smallRNA/smallrna.html . The new small RNA sequences published since our last compilation are listed in this paper (Table 1).

Animals↗

PubMed1998

Off-resonance proton T1rho dispersion imaging of 17O-enriched tissue phantoms.

Proton T1rho dispersion imaging is a recently described method for indirect detection of 17O. However, clinical implementation of this technique is hindered by the requirement for a high-amplitude spin-locking field (gammaB1 > 1 kHz) that exceeds current limitations in specific absorption rate (SAR). Here, a strategy is offered for circumventing high SAR in T1rho dispersion imaging of 17O through the use of low-amplitude off-resonance spin-locking pulses (gammaB1 < 300 Hz). Proton spin-lattice relaxation times in the off-resonance rotating frame were measured in H2(17)O-enriched tissue phantoms. On- and off-resonance T1rho dispersion imaging was implemented at 2 T using a spin-locking preparatory pulse cluster appended to a standard spin-echo sequence. On- and off-resonance dispersion images exhibited similar 17O-based image contrast. Magnetization transfer effects did not depend on 17O concentration and had no effect on image contrast. In conclusion, off-resonance proton T1rho dispersion imaging shows promise as a safe, sensitive technique for generating 17O-based T1rho contrast without exceeding SAR limitations.

Absorption↗

PubMed1998

Sodium MRI of human articular cartilage in vivo.

Preliminary results from in vivo sodium MRI of human patellar articular cartilage are presented. Sodium images generated of an in vitro bovine patella clearly distinguish the region of proteoglycan depletion from the region of healthy cartilage. This provides the first evidence that sodium imaging may be used to detect changes due to osteoarthritis in vivo. The process of optimizing imaging time and signal-to-noise ratio, as well as potential implications in the detection of osteoarthritic change, are discussed.

Animals↗

PubMed1998

MRI of hyperpolarized 3He gas in human paranasal sinuses.

In this study, MRI of hyperpolarized 3He gas in human paranasal sinuses is presented. Helium images were obtained at 1.5 T, using a surface coil and a 2D, fast gradient-echo sequence with a nominal constant flip angle of 12 degrees. Coronal images of 20-mm thick slices were generated and compared with proton images of the corresponding sections. The images enable visualization of the paranasal sinuses and the nasal cavity, suggesting a potential use of this method not only in identifying the anatomical configuration of these pneumatic spaces, but also in assessing sinus ventilation.

Adult↗

PubMed1998

Sodium multiple quantum spectroscopy of articular cartilage: effects of mechanical compression.

The effects of mechanical compression on the multiple quantum coherences generated from sodium ions in articular cartilage were investigated. Cartilage samples obtained from bovine patellae were studied during compression at 0.7 MPa (100 psi) for 1 hour. The double quantum filtered spectra showed marked lineshape changes in the compressed samples. Compression did not seem to influence the lineshapes of the single quantum and triple quantum filtered spectra significantly. We found that the residual quadrupolar interaction was reduced in the compressed samples. Changes in the ordering of collagen fibers may be responsible for the observed effect.

Animals↗

PubMed1998

Percutaneous dilatation of biliary strictures through the afferent limb of a modified Roux-en-Y choledochojejunostomy or hepaticojejunostomy.

BACKGROUND: This report is a 13-year prospective evaluation of percutaneous balloon dilatation of benign biliary strictures through the subcutaneous or subfascially positioned afferent limb of a choledocho or hepaticojejunostomy in 30 patients. DATA SOURCE: Twenty-seven strictures developed after a common duct injury sustained at the time of cholecystectomy, two after hepatectomy reconstruction for trauma and one following a gastrectomy. Twelve injuries (40%) were recognized at operation. Of the 18 patients where the injury was unrecognized at the time of operation, 8 had not been reoperated at the time of referral, 7 had late repairs by the referring physician, and 3 had late repairs at our institution. The follow-up is 1 to 13 years. RESULTS: There has been 1 late death and 6 patients are lost alive. The jejunal-limb was accessed 50 times with two minor and no major complications. There have been two parajejunal hernia repairs, but there have not been any reoperations for recurrent biliary strictures. CONCLUSIONS: Benign biliary strictures can be effectively managed by repeat balloon dilatations thru the afferent limb of a choledocho or hepaticojejunostomy, thus eliminating the need for repeat surgical interventions.

Adult↗

PubMed1998

Laparoscopic cholecystectomy in cirrhotic patients.

BACKGROUND: Reported mortality for open cholecystectomy in patients with cirrhosis ranges from 10% to 80%. Laparoscopic cholecystectomy has gained acceptance in the general population and has become the procedure of choice for symptomatic cholelithiasis. We reviewed our experience with the use of laparoscopic cholecystectomy in this group. STUDY DESIGN: We did a retrospective review of the records of 25 consecutive laparoscopic choleoystectomy procedures performed on cirrhotic patients from May 1992 to July 1996. RESULTS: There were no mortalities in our group. All procedures were completed laparoscopically. Mean length of stay was 1.7 days (range, 1 to 8 days). Morbidity consisted of wound hematomas, pneumonia, and ascites for a rate of 32%. Only patients with Child's Class A and Class B cirrhosis were operated on. CONCLUSIONS: Laparoscopic cholecystectomy can be performed safely in cirrhotic patients with well compensated liver function.

Adult↗

PubMed1998

Stepwise transplantation of an active site loop between heat-labile enterotoxins LT-II and LT-I and characterization of the obtained hybrid toxins.

Members of the cholera toxin family, including Escherichia coli heat-labile enterotoxins LT-I and LT-II, catalyze the covalent modification of intracellular proteins by transfer of ADP-ribose from NAD to a specific arginine of the target protein. The ADP-ribosylating activity of these toxins is located in the A-subunit, for which LT-I and LT-II share a 63% sequence identity. The flexible loop in LT-I, ranging from residue 47 to 56, closes over the active site cleft. Previous studies have shown that point mutations in this loop have dramatic effects on the activity of LT-I. Yet, in LT-II the sequence of the equivalent loop differs at four positions from LT-I. Therefore five mutants of the active site loop were created by a stepwise replacement of the loop sequence in LT-I with virtually all the corresponding residues in LT-II. Since we discovered that LT-II had no activity versus the artificial substrate diethylamino-benzylidine-aminoguanidine (DEABAG) while LT-I does, our active site mutants most likely probe the NAD binding, not the arginine binding region of the active site. The five hybrid toxins obtained (Q49A, F52N, V53T, Q49V/F52N and Q49V/F52N/V53T) show (i) great differences in holotoxin assembly efficiency; (ii) decreased cytotoxicity in Chinese hamster ovary cells; and (iii) increased in vitro enzymatic activity compared with wild type LT-I. Specifically, the three mutants containing the F52N substitution display a greater Vmax for NAD than wild type LT-I. The enzymatic activity of the V53T mutant is significantly higher than that of wild type LT-I. Apparently this subtle variation at position 53 is beneficial, in contrast to several other substitutions at position 53 which previously had been shown to be deleterious for activity. The most striking result of this study is that the active site loop of LT-I, despite great sensitivity for point mutations, can essentially be replaced by the active site loop of LT-II, yielding an active 'hybrid enzyme' as well as 'hybrid toxin'.

Adenosine Diphosphate Ribose↗

PubMed1998

Houseflies are an unlikely reservoir or vector for Helicobacter pylori.

The route of transmission of Helicobacter pylori from individual to individual remains undefined. It has recently been reported that the domestic housefly, Musca domestica, when fed pure cultures of H. pylori, was able to harbor the organism in its midgut for up to 30 h (P. Grubel, S. Hoffman, F. K. Chong, N. A. Barstein, C. Mepani, and D. R. Cave, J. Clin. Microbiol. 35:1300-1303, 1997). Our investigation examined whether houseflies could acquire H. pylori from fresh human feces. Domestic houseflies (40 flies/group) were exposed for 24 h to feces from an H. pylori-positive volunteer, feces from an H. pylori-negative volunteer, or feces from an H. pylori-negative volunteer to which a known amount of viable H. pylori had been added. At various intervals, flies were sacrificed and the midguts were excised, homogenized, and plated in duplicate onto selective horse blood agar plates. All plates were incubated under microaerobic conditions at 37 degreesC for 14 days. Emergent colonies presumptive of H. pylori were picked and tested biochemically to confirm the identity as H. pylori. H. pylori was not recovered from houseflies fed human feces either naturally infected or artificially infected with H. pylori. These results suggest that the domestic housefly is not a vector for transmission or a reservoir for H. pylori infection.

Animals↗

PubMed1998

The Splendore-Hoeppli phenomenon in hepatic botryomycosis.

A 68 year old diabetic man developed septicaemia and multiple liver abscesses due to Streptococcus intermedius. Liver biopsy revealed streptococcal botryomycosis which showed the Splendore-Hoeppli phenomenon. Diabetes mellitus is an example of the immunosuppressed states that have been associated with botryomycosis.

Aged↗

PubMed1998

A comparative study of retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements with stainless steel crowns--an in vitro study.

This study was conducted on 30 extracted human primary molars to assess the retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements. The teeth were embedded in resin blocks and were randomly divided into 3 groups of 10 each. The occlusal surfaces of all teeth were reduced uniformly by 1.0 to 1.5 mm. All mesial, distal undercuts were removed and sharp angles rounded. This was followed by cementing pretrimmed and precontoured stainless steel crowns on each tooth with hand pressure and storing in artificial saliva at 37 degrees C for 24 hours. Retentive strength was tested using Instron Universal Testing Machine. The load was applied starting from a zero reading and gradually increased until the cemented stainless steel crowns showed signs of movement and then the readings were recorded. It was found that retentive strengths of zinc phosphate and glass ionomer cements were statistically better (P < 0.05) when compared to the polycarboxylate cement. Negligible difference (0. 59 kg/cm2) was however observed between zinc phosphate and glass ionomer cements.

Analysis of Variance↗

PubMed1998

Vital signs services for secure telemedicine applications.

Telemedicine using teleconference provides only a part of the picture. The remote patient's electronic medical record and vital signs may often be essential for proper diagnosis and treatment. While there are commercial solutions for telemonitoring, they do not address issues such as security and interoperability leveraging the growing public communications infrastructure. On the other hand there are performance considerations due to the quality of service over available communications media that can hinder real-time operation. The objective of this research effort is to develop secure tele-monitoring facilities that enable healthcare providers to collaborate over public communication networks; to securely convey their patient's vital signs to a remote specialist; and to enable "near real-time" examination of those vital sign data. It is our belief that such applications can help overcome barriers to quality healthcare in the scattered populations of rural areas enabling telemedicine to be a part of the practice of medicine. The authors, who are developing secure telemedicine applications, describe their approach in developing secure vital signs services.

Blood Pressure↗

PubMed1997

Formation of 2',3'-cyclic phosphates at the 3' end of human U6 small nuclear RNA in vitro. Identification of 2',3'-cyclic phosphates at the 3' ends of human signal recognition particle and mitochondrial RNA processing RNAs.

Approximately 90% of human U6 small nuclear RNA (snRNA) contains uridine cyclic phosphate (U>p) at its 3'-end (Lund, E., and Dahlberg, J. E. (1992) Science 255, 327-330). We studied the formation of U>p at the 3' end of human U6 snRNA using an in vitro system where uridylic acid residues are added from UTP precursor and U>p is formed. Analysis of U6 snRNAs with varying number of uridylic acid residues showed that each of these species contains U>p where the phosphate originated from alpha-phosphate of UTP precursor. The cyclic phosphate formation occurred on U6 snRNA in extracts where essential spliceosomal snRNAs were specifically degraded, thereby indicating that U>p formation is not coupled to pre-mRNA splicing. A subpopulation of human signal recognition particle and mitochondrial RNA processing RNAs isolated from HeLa cells also contained cyclic phosphates at their 3' ends. These data suggest that U>p in U6 snRNA is unlikely to be related to its participation in splicing of pre-mRNAs. It appears that cyclic phosphate is an intermediate product in the metabolism of these small RNAs.

HeLa Cells↗

PubMed1997

Small RNA database.

The small RNA database is a compilation of all the small size RNA sequences available to date, including nuclear, nucleolar, cytoplasmic and mitochondrial small RNAs from eukaryotic organisms and small RNAs from prokaryotic cells as well as viruses. Currently, about 600 small RNA sequences are in our database. It also gives the sources of individual RNAs and their GenBank accession numbers. The small RNA database can be accessed through WWW(World Wide Web). Our WWW URL address is: http://mbcr.bcm.tmc.edu/smallRNA/smallrna. html . The new small RNA sequences published since our last compilation are listed in this paper.

Animals↗

PubMed1997

In vivo sodium multiple quantum spectroscopy of human articular cartilage.

The authors report, for the first time, sodium properties of human articular cartilage in vivo using sodium multiple-quantum-filtered methods with a surface coil. A flip angle-independent, phase-cycled pulse sequence was used to obtain triple-quantum-filtered spectra as a function of preparation time. Biexponential relaxation rates were calculated by fitting the triple-quantum-filtered spectral amplitudes to a theoretical expression. Theoretical analysis of the flip angle dependence of even rank two-quantum coherence (T2[2]), odd rank two-quantum coherence (T2[3]), and triple-quantum coherence are presented and verified against experimental results on a cartilage specimen. Sodium multiple-quantum-filtered spectral lineshapes obtained in vivo correlate well with those observed on in vitro specimens. Relaxation rates obtained from asymptomatic volunteers were found to be: T(2rise) = 1.0 + 0.12 ms, T(2decay) = 12.0 +/- 0.75 ms (mean +/- SD). The diagnostic potential of this method in detecting early changes in articular cartilage is described.

Animals↗

PubMed1997

Triple quantum sodium imaging of articular cartilage.

Triple quantum (TQ) sodium imaging of bovine articular cartilage is presented. True triple quantum imaging sequence was modified to incorporate asymmetric echo acquisition. Triple quantum signal expression in the presence of residual quadrupolar interaction is presented. The filtering capability of the sequence is first demonstrated on an agarose phantom. Both single and triple quantum images of articular cartilage are compared. The TQ image shows non-zero signal intensity solely from cartilage, indicating complete suppression of signals from bone marrow and saline. The advantages of TQ imaging of articular cartilage, its feasibility in in vivo situations and further improvements in SNR are described.

Animals↗