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Biomedical subjects

P Reddy

Publications and source records attributed to P Reddy.

At least 127 records · Page 7Linked to original sources
PubMed1987

Prostatic urethra: experimental dilation in dogs.

An animal study was undertaken to develop a balloon dilation technique that could be used in humans to treat the common ailment of benign prostatic hypertrophy. Dogs were used as a model because of the similarities in the prostate between the two species and the ready availability of the canines. A retrograde transurethral approach was used for dilation. Balloon catheters, 8-20 mm in diameter, were used. Significant, long-lasting dilatation of the prostatic urethra was not accomplished until 20-mm balloons (or two 10-mm ones) inflated for 10 minutes were used. The animals were followed for up to 14 months. No deleterious histologic effects of dilation were identified within the urethra or prostate that could lead to stenosis of the prostatic urethra in later stages.

Animals↗
PubMed1987

Benign prostatic hypertrophy: retrograde transurethral dilation of the prostatic urethra in humans. Work in progress.

Retrograde transurethral balloon dilation of the prostatic urethra was performed in five human volunteers with benign prostatic hypertrophy. Each patient underwent cystoscopy, uroflow studies, voiding cystourethrography, retrograde urethrography, and magnetic resonance imaging before dilation and at defined intervals afterward. The longest follow-up to date is 8 months. Patients were given topical anesthetics and mild sedatives, and dilation was performed with a 25-mm urethroplasty balloon catheter inflated at 3-6 atm for 10 minutes. All catheter manipulations were done with a guide wire and under fluoroscopic control. Significant resolution of symptoms of prostatism was seen in four patients. The unsatisfactory results in the last patient were believed to be caused by ineffectual dilation of predominantly middle lobe hypertrophy--a condition that is now regarded as a contraindication to dilation. This technique has promise to replace transurethral resection of the prostate as the treatment of choice for this common male ailment.

Aged↗
PubMed1986

Stimulation of Escherichia coli adenylate cyclase activity by elongation factor Tu, a GTP-binding protein essential for protein synthesis.

A unique feature of eucaryotic adenylate cyclases is their interaction with GTP-binding proteins that mediate hormonal responses. Until now, there has been no evidence for regulation of Escherichia coli adenylate cyclase by a GTP-binding protein. We describe here that the most abundant protein in E. coli, the GTP-binding protein EF-Tu, which is important as an elongation factor in protein synthesis, also serves as a stimulator of adenylate cyclase activity. Homogeneous EF-Tu specifically increased the activity of purified adenylate cyclase as much as 70%; other E. coli GTP-binding proteins had no effect on enzyme activity. A study of the guanine nucleotide specificity for EF-Tu-mediated stimulation of adenylate cyclase activity suggested that the preferred activator is EF-Tu X GDP. To account for the GTP-specific stimulation of adenylate cyclase activity observed in intact cells, we propose that the nucleotide specificity for EF-Tu-dependent activation of adenylate cyclase is governed by other factors in the cell.

Adenylyl Cyclases↗
PubMed1986

The period clock locus of D. melanogaster codes for a proteoglycan.

The period (per) gene of D. melanogaster is involved in the generation of biological rhythms. The most striking feature of the predicted coding sequence, corresponding to the key 4.5 kb transcript from this locus, is an extensive run of alternating Gly-Thr residues. This is homologous to a series of Gly-Ser repeats in a chondroitin sulfate proteoglycan. To determine whether the per transcript codes for a proteoglycan, a region of its coding sequence was expressed (in bacteria) as part of a fusion protein, which was used to immunize rabbits. When the resultant immune sera were used to probe fly protein preparations, they detected an antigen that is present in wild-type flies and absent in a per- mutant. Biochemical characterization of this antigen indicated that it is indeed a proteoglycan.

Amino Acid Sequence↗
PubMed1986

Embryonic expression of the period clock gene in the central nervous system of Drosophila melanogaster.

We have examined the temporal and spatial expression of the 4.5-kb mRNA that is transcribed from the period locus of Drosophila melanogaster and is the best candidate for the per gene product. Both Northern blot analyses and hybridizations in situ to tissue sections reveal significant expression of the 4.5-kb mRNA in embryos. This expression is limited to the central nervous system of the developing embryo and is localized within the brain and ventral ganglia. The 4.5-kb mRNA is enriched in adult heads (by Northern blotting) although we were not able to detect specific localization (in situ). In addition to the physiological role the 4.5-kb mRNA might have in maintaining biological rhythms, we now suggest that it has a developmental role for establishing mechanisms that are necessary for eventual expression of clock functions.

Animals↗
PubMed1986

Retroviruses in radiation-induced lymphomas.

The nucleotide sequence of RadLV/VL3 (T+L+), the thymotropic and leukemogenic entity of the in-vitro propagated radiation leukemia virus complex (RadLV/VL3), is that of a recombinant retrovirus. The gag, pol and most of the env gene are very similar to the homologous regions of Akv MuLV. The 3' end of the env gene and the LTR appear to have derived from a xenotropic MuLV. However, the LTR has acquired a feature shared by other lymphomagenic MuLVs. This feature consists in sequence rearrangements resulting in the generation of presumed enhancer elements. RadLV/VL3(T+L+)-specific proviral sequences were found adjacent to the c-myc gene in several virus-induced thymic lymphomas of the rat, suggesting that the enhancer elements might play a role in lymphomagenesis. However, we found that the presence of a provirus at a specific DNA site can lead to an in-vitro growth advantage and to clonal cell selection independently of a lymphomagenic process. We conclude from this observation that clonal appearance of an integrated provirus in cultured radiogenic lymphoma cells does not necessarily reflect a viral induction of radiation-induced leukemogenesis.

Animals↗
PubMed1986

Intraocular magnet of Parel.

The intraocular magnet (IOM) is a new device based on permanent magnetism providing controlled energy for removal of magnetic intraocular foreign bodies. Its use is reported in 11 cases.

Adolescent↗
PubMed1986

The double puncture: an effective percutaneous technique for removing complex, multiple renal calculi.

Percutaneous nephrostolithotomy, which can require a double puncture, is presently the method of choice in our institution for the removal of renal stones. Patients that underwent this procedure were evaluated to identify the possible reasons for the double puncture. Of 200 patients evaluated, 14 needed a second tract. The three variables that determined whether a second puncture was needed, in order of importance, were number and size of the stones, with second tracts needed in patients with multiple stones and staghorn calculi; anatomical variations of the renal collecting system itself, with bifid systems the most significant anatomic variation; and the dexterity of the radiologist in performing the puncture and the ability of the urologist to extract the stone. Second tracts were needed more frequently in patients who presented with stones in both the lower and middle poles of the collecting systems.

Humans↗
PubMed1986

Germ-line transformation involving DNA from the period locus in Drosophila melanogaster: overlapping genomic fragments that restore circadian and ultradian rhythmicity to per0 and per- mutants.

P-element-mediated transformations involving DNA fragments from the period (per) clock gene of Drosophila melanogaster have shown that several subsegments of the locus restore rhythmicity to per0 or per- mutants. Such fragments overlap in a genomic region complementary to one transcript, a 4.5-kb RNA which is probably the per message, in that it is necessary and (in terms of expression from this X-chromosomal locus) sufficient for the fly's circadian rhythms. It is also at least necessary for the high-frequency oscillations normally produced by courting males as they vibrate their wings. The entirety of the 4.5-kb transcript is not necessary for rather strong rhythmicity; nor does it seem to be sufficient, in transformants, for wild-type behavioral phenotypes. A 0.9-kb RNA, homologous to genomic region immediately adjacent to the source of the 4.5-kb species, oscillates in its abundance over the course of a day; but coverage of this transcript source in several transformants carrying a per0 mutation--which eliminates the 0.9-kb RNA's oscillation--does not restore rhythmicity. All of the independently isolated arrhythmic mutations tested were covered by the same array of overlapping per+-derived DNA fragments, implying that the only portion of the locus which has mutated to arrhythmicity is complementary to the 4.5-kb transcript.

Animals↗
PubMed1985

The Escherichia coli adenylate cyclase complex. Stimulation by potassium and phosphate.

In Escherichia coli, adenylate cyclase activity in toluene-treated cells can be inhibited by glucose while the activity in a broken cell preparation cannot. Adenylate cyclase activity in the permeabilized but not in broken cells is stimulated somewhat specifically and additively by potassium and phosphate. Kinetic studies show sigmoid substrate-velocity curves for the toluene-treated cells but hyperbolic curves for the broken cells. The stimulatory effects of potassium and phosphate on adenylate cyclase activity in tolulene-treated cells are associated with increases in the Vmax and Km for ATP. While the enzyme activity in toluene-treated cells shows a preference for magnesium over manganese, the reverse is observed in broken cells. Stimulation of adenylate cyclase activity in toluene-treated cells requires the presence of the proteins of the phosphoenolpyruvate:sugar phosphotransferase system (PTS). The PTS proteins can be phosphorylated in a P-enolpyruvate-dependent reaction. The stimulatory effects of ions will not occur if the PTS proteins are not phosphorylated. Since potassium phosphate stimulates both adenylate cyclase and PTS activities in toluene-treated cells, it is proposed that the effect of potassium phosphate on adenylate cyclase activity is mediated through an effect on the PTS. A model for dual regulation by glucose of adenylate cyclase activity is proposed. This model involves regulation of both the condition of the PTS proteins as well as the cellular concentration of phosphate.

Adenylyl Cyclases↗
PubMed1985

Translational efficiency of the Escherichia coli adenylate cyclase gene: mutating the UUG initiation codon to GUG or AUG results in increased gene expression.

Roy et al. [Roy, A., Haziza, C. & Danchin, A. (1983) EMBO J. 2, 791-797] established that translation of Escherichia coli adenylate cyclase initiates at a UUG codon, and they suggested this might decrease the efficiency of translation. We investigated the effect of varying the initiation codon on the expression of the adenylate cyclase (cya) gene. Using oligonucleotide-directed mutagenesis, we changed the UUG initiation codon to GUG and the more common initiator AUG and assayed for cya gene expression in a number of ways. First, the GUG initiation codon, in place of UUG, doubled cya expression when cya was expressed from the dual cya P1/P2 promoters. The corresponding AUG codon construct was nonviable. Second, when the cya gene was placed under the transcriptional control of the thermoinducible phage lambda PL promoter, the relative amounts of cya gene product were 1:2:6 for the UUG, GUG, and AUG initiation codons, respectively. Finally, the cya P2 promoter, Shine-Dalgarno sequence, and the DNA corresponding to the first 86 codons of cya were fused to DNA encoding the E. coli galactokinase gene beginning at the second codon. The relative amounts of the fusion polypeptides, which had galactokinase activity, were 1:2:3 for the UUG, GUG, and AUG initiation codons, respectively. These results demonstrate that the cya UUG initiation codon limits cya expression at the level of translation.

Adenylyl Cyclases↗
PubMed1985

Molecular structure of the human cytoplasmic beta-actin gene: interspecies homology of sequences in the introns.

A recombinant phage that carries the cytoplasmic beta-actin gene was isolated from a human DNA library. The nucleotide sequence of this gene was determined. The amino acid sequence deduced from the nucleotide sequence matches perfectly that of beta-actin from human fibroblasts. The gene contains five introns. A large intron was found in the 5' untranslated region six nucleotides upstream from the ATG initiation codon. Four introns were found within the coding region at codons specifying amino acids 41/42, 121/122, 267, and 327/328. In contrast to the human cardiac muscle actin gene, the aorta-type smooth muscle actin gene, and the stomach-type smooth muscle actin gene, the beta-actin gene lacks the codon for cysteine between the ATG initiation codon and the codon for the NH2-terminal amino acid of the mature protein. Hybridization of genomic DNA with DNA fragments derived from intron I in the 5' untranslated region and from intron III strongly suggests the presence of a single beta-actin gene in the human genome. The DNA sequences of the coding region, of the 3' untranslated region, and of the sequence block between the "CCAAT" box and "TATA" box in the 5' flanking DNA of the human beta-actin gene are highly homologous to the corresponding sequences of the rat and chicken beta-actin genes. Unexpectedly, the sequence of intron III of the human beta-actin gene shows considerable homology to that of the rat beta-actin gene.

Actins↗
PubMed1985

Reconstitution of regulatory properties of adenylate cyclase in Escherichia coli extracts.

The inhibition of adenylate cyclase activity of Escherichia coli by methyl alpha-glucoside has been demonstrated in intact or in permeable cells but not in cell-free extracts. In intact or permeable cells, this inhibition is demonstrable only in strains expressing the genes for proteins of the phosphoenolpyruvate:glycose phosphotransferase system (PTS); in permeable cells, the inhibition also requires potassium phosphate. Using homogeneous proteins of the PTS, we have reconstituted in cell-free extracts many of the features of the regulated form of adenylate cyclase: (i) In the absence of K2HPO4, permeable cells have lower adenylate cyclase activity than extracts; addition of homogeneous PTS proteins to the extracts brings adenylate cyclase activity close to the level observed in permeable cells. (ii) The low activity observed in permeable cells is stimulated by potassium phosphate; this stimulation is also observed in extracts supplemented with PTS proteins and phosphoenolpyruvate. (iii) In permeable cells, potassium phosphate-stimulated adenylate cyclase activity is inhibited by methyl alpha-glucoside or pyruvate; extracts behaved similarly when supplemented with PTS proteins, K2HPO4, and phosphoenolpyruvate. Thus, the regulated form of adenylate cyclase has been reconstituted in cell-free extracts by addition of homogeneous PTS proteins.

Adenylyl Cyclase Inhibitors↗
PubMed1985

Percutaneous extraction of urinary calculi: use of the intercostal approach.

The authors achieved successful percutaneous extraction of urinary calculi via an intercostal approach in 24 patients. In one patient, a large hydrothorax developed and thoracentesis was required; 2 patients had moderate and 6 minimal pleural fluid collections which did not require treatment. No patient had pneumothorax. Intercostal puncture provides direct access to the upper and middle poles of the kidney when they lie above the twelfth rib and subcostal angulation is not feasible. Such an approach is advantageous for stones in the ureter, as well as renal stones which are inaccessible from the lower pole. Fluoroscopy should be performed when planning the puncture in order to avoid the lung, and a working sheath is recommended.

Adult↗
PubMed1985

Percutaneous nephrostolithotomy: application to staghorn calculi.

Twenty-five renal staghorn stones measuring at least 5 cm in diameter were removed percutaneously from 24 patients. Twelve patients required multiple access tracts for complete stone removal. Estimated blood loss more than 1000 ml occurred in 16 patients and temperature greater than 38.5 degrees C in 19 patients. All stones were successfully removed, with only two patients having definite residual fragments. Percutaneous nephrostolithotomy may be successfully applied to large staghorn stones. The relative roles of percutaneous therapy and extracorporeal lithotripsy remain to be determined.

Adult↗
PubMed1984

Transurethral treatment of bladder diverticula. Alternative to open diverticulectomy.

Since October, 1980, we have used transurethral fulguration of the diverticular mucosa and incision of the diverticular neck in combination with electrohydraulic lithotripsy of bladder stones and transurethral prostatic resection to treat all aspects of diverticula in 11 patients. In comparing the results with those of open diverticulectomy, we found the transurethral procedure to be equally effective while being safer, faster, and less expensive.

Aged↗
PubMed1984

P-element transformation with period locus DNA restores rhythmicity to mutant, arrhythmic Drosophila melanogaster.

Mutations at the period (per) locus of Drosophila melanogaster disrupt several biological rhythms. Molecular cloning of DNA sequences encompassing the per+ locus has allowed germ-line transformation experiments to be carried out. Certain subsegments of the per region, transduced into the genome of arrhythmic pero flies, restore rhythmicity in circadian locomotor behavior and the male's courtship song.

Animals↗