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Biomedical subjects

J J Duffy

Publications and source records attributed to J J Duffy.

At least 37 records · Page 2Linked to original sources
PubMed1986

Lawn dart injury in children: report of two cases.

Two cases of intracranial penetration by lawn darts are presented in this report. Both patients were children who developed infectious sequelae following primary closure of cutaneous puncture wounds. These injuries suggest that the darts produced a high-energy impact force that resulted in skull fractures and focal cerebral injury. When children present with puncture wounds or lacerations produced by lawn darts, intracranial penetration must be ruled out, using appropriate medical imaging. Parents should be advised regarding the need for medical reassessment should fever, headache, or local signs of infection occur.

Accidents, Home↗
PubMed1985

Inhibition by retinoic acid of murine retrovirus-induced cellular transformation and tumor formation.

The effect of all-trans-retinoic acid (RA) on cellular transformation and on tumorigenicity of retrovirally transformed cells was investigated. RA treatment of NRK and NIH/3T3 cells transformed by BALB/c murine sarcoma virus (MuSV), Kirsten murine sarcoma virus (K-MuSV), and simian sarcoma virus resulted in a significant reduction in anchorage-dependent growth of only K-MuSV-transformed NRK cells. A 62% reduction in cell number was observed at 10(-5) M RA. In contrast, anchorage-independent growth induced by each of the viruses tested was suppressed by RA. Balb/cMSV3T3 cells showed the greatest level of sensitivity with a significant reduction in anchorage-independent growth occurring at 10(-9) M RA. The level of cytoplasmic retinoic acid-binding protein (CRABP) was determined in both parent and transformed cell lines. CRABP was present at a high level in all 3T3 cell types but was absent in all NRK cell lines. For testing the antineoplastic activity of RA in vivo, Balb/cMSV3T3 cells were injected intradermally into nude mice. Subsequent treatment of the tumor sites of these animals by topical application of RA resulted in a significant reduction in both tumor incidence and tumor size, confirming the in vitro results. Analysis of the level of v-onc mRNA revealed that inhibition of retroviral transformation by RA was not due to a decrease in transcription of the v-onc genes.

Animals↗
PubMed1982

Interaction of Bacillus subtilis RNA polymerase core with two specificity-determining subunits. Competition between sigma and the SPO1 gene 28 protein.

Gene activity in the development of phage SPO1 is transcriptionally regulated. Early viral genes are transcribed by the major vegetative cell RNA polymerase (E. sigma). Middle viral genes are transcribed by RNA polymerase core (E) bearing the SPO1 gene 28 protein (gp28) instead of sigma. This paper deals with the competitive interactions of sigma and gp28 with E which must, at least in part, be involved in the ability of viral middle gene expression to succeed early gene expression. An in vitro assay has been developed for determining the proportions of early (E. sigma) and SPO1 middle (E.gp28) Bacillus subtilis RNA polymerase in mixtures. The assay, which is based on the transcription of two well studied SPO1 restriction fragments followed by gel electrophoresis and quantitation of the E. sigma and E.gp28 transcription products, has been used to study the interactions of sigma and gp28 with RNA polymerase core. These subunits are found to be capable of competitively excluding each other. The binding competition is sensitive to ionic strength, with sigma being more effective below 0.2 total ionic strength and gp28 being more effective at higher values. The outcome of competition is also dependent on the order of addition of subunits and the reconstitution kinetics have been studied. The subunit competition is rather insensitive, particularly at higher ionic strength, to temperature. Gp28 can convert E. sigma to E.gp28 but the reverse reaction occurs much less efficiently. The B. subtilis delta protein biases the sigma-gp28 competition in favor of the sigma subunit. the implications of these results for the physiological transition of transcriptional specificity during SPO1 development are discussed.

Bacillus subtilis↗
PubMed1982

Transcription in aging: the response of rat liver nuclear RNA polymerases to cycloheximide in vivo.

Experiments were performed to address the known relationship between diet and longevity. The acute response of rat liver nuclear RNA polymerases to inhibition of protein synthesis by cycloheximide (10 mg/kg) was quantitated in rats of varying ages. Thirty minutes after cycloheximide administration, there was a "compensatory" 1.5--2-fold increase in RNA polymerase II activity at all ages. Nucleolar RNA polymerase I activity was significantly diminished only up to 4 months, indicating a loss in tight control coupling of protein synthesis to rRNA synthesis with age.

Aging↗
PubMed1982

Development of an antibody to actinomycin D and its application for the detection of serum levels by radioimmunoassay.

An antibody specific for actinomycin D (Act D) has been developed and used in a rapid, sensitive radioimmunoassay for detection of this anticancer drug in serum. The 2-amino group of the heterocyclic chromophore of Act D was covalently coupled to available free carboxyl groups of bovine serum albumin with carbodiimide. The resulting complex was then used for the production of a specific antibody to Act D in two male New Zealand rabbits. Antibody production was of sufficient titer in both rabbits to allow the development of a radioimmunoassay for the free drug which is rapid and sensitive enough to accurately measure 0.1 pmol of Act D. The antibody produced was characterized to be immunoglobulin G by virtue of its ability to bind to Protein A:Sepharose columns. With the use of Act-D analog, actinomine, the antibody was characterized to be specific for the pentapeptide portion of the molecule. Pharmacokinetic analysis of serial serum samples obtained from a patient who received the drug i.v. revealed a biphasic response with an alpha-serum half-life of 1.78 and a beta serum half-life of 34 min. An i.v. injection of Act D into a dog and assay of serum concentration revealed a similar biphasic response with an alpha serum half-life of 0.78 min and a beta-serum half-life of 208 min.

Animals↗
PubMed1979

Enhanced transcription by RNA polymerases II and III after inhibition of protein synthesis.

Intraperitoneal administration of cycloheximide (100 mg/kg) to rats produces a time-dependent rise in nuclear RNA polymerase II activity which is maximum at 30 min. This same concentration of cycloheximide also reduces RNA polymerase I activity to 64% of control within this time period. When 10 mg/kg of cycloheximide was administered, there was a 2-fold increase in both RNA polymerases II and III activities within 30 min as assayed in isolated nuclei. When these enzymes are solubilized from nuclei and resolved by DEAE-Sephadex, there is no significant change in the activity of RNA polymerase I or II when assayed on an exogenous template. It is suggested that the dual enhancement of nuclear RNA polymerase II and III activities is the result of a compensatory feedback relationship which exists between translation and transcription in vivo.

Animals↗
PubMed1976

The virus-specified subunits of a modified B. subtilis RNA polymerase are determinants of DNA binding and RNA chain initiation.

The phage SPO1-modified RNA polymerase B-P can form rapidly initiating complexes with SPO1 DNA but not with heterologous phi1 DNA. The B-P enzyme binds only weakly to heterologous phi29 DNA: preincubation with phi29 DNA does not substantially slow the formation of rapidly initiating complexes between polymerase B-P and subsequently added SPO1 DNA. In contrast, B. subtilis holoenzyme and core polymerase are substantially sequestered by preincubation with phi29 DNA. The results show that at least one of the phage SPO1-coded subunits of the polymerase B-P determines selective transcription at the level of DNA binding and RNA chain initiation, weakens the binding of RNA polymerase core to heterologous DNA, and discriminates against promoter complex formation at certain promoters that are utilized by the B. subtilis holoenzyme.

Bacillus subtilis↗
PubMed1975

RNA polymerase from phage SP01-infected and uninfected Bacillus subtilis.

A purification procedure for RNA polymerase from uninfected and phage SP01-infected Bacillus subtilis is presented. The RNA polymerase purified from B. subtilis 10 min after infection with wild type phage SP01 is resolved into two major fractions (B, C) and one minor fraction (A) by calf thymus DNA-cellulose chromatography. Fraction C is indistinguishable from RNA polymerase from uninfected cells with respect to transcription specificity (both before and after phosphocellulose chromatography). Fraction B yields, on subsequent phosphocellulose chromatography, an enzyme (B-P) whose properties distinguish it from the host RNA polymerase. Enzyme B-P preferentially transcribes SP01 DNA and selectively forms rapidly initiating complexes with SP01 DNA but not with heterologous DNA. The SP01 RNA synthesized by Enzyme B-P includes, as previously reported, a large proportion of asymmetrical middle viral RNA. Host RNA polymerase holoenzyme synthesizes asymmetrical early viral RNA, while host core polymerase synthesizes symmetrical RNA that is complementary to early, middle, and late in vivo viral RNA and contains a preponderance of antimessenger. The subunit composition of Enzyme B-P is identical to host core polymerase with respect to the beta,beta', and alpha subunits and two additional components of mr equals 9,500 and 11,000 that we observe in all preparations of RNA polymerase. In addition, Enzyme B-P has two subunits of mr equals 13,000 and 28,000, which are synthesized after phage infection. On heterologous template, Enzyme B-P and host core polymerase have comparable activities. On these templates, addition of host initiation factor, sigma, restores full activity to Enzyme B-P as well as to host core polymerase. Sigma also modifies the activity of Enzyme B-P on SP01 DNA, restoring some asymmetrical early RNA transcription while retaining some asymmetrical middle RNA transcription.

Animals↗
PubMed1975

Conversion of Bacillus subtilis RNA polymerase activity in vitro by a protein induced by phage SP01.

A protein fraction from B. subtilis infected with phage SP01 (fraction LGG) stimulates the activity of RNA polymerase (EC 2.7.7.6; nucleosidetriphosphate:RNA nucleotidyltransferase) core from uninfected bacteria. Fraction LGG contains a protein (P-28, molecular weight 28,000) that is labeled after phage infection and binds tightly to RNA polymerase core at a relatively high ionic strength. B. subtilis RNA polymerase core with bound P-28 has the transcription specificity of the previously purified, phage-modified B-P RNA polymerase; the latter contains two subunits, v-28 and v-13 (molecular weights 28,000 and 13,000, respectively) that are synthesized after phage infection. Both enzymes transcribe SP01 DNA preferentially and direct the asymmetric synthesis of viral middle RNA. P-28, like v-28, binds more tightly to B. subtilis RNA polymerase core than the B. subtilis initiation factor, sigma, at higher ionic strength. We propose that P-28 and v-28 are the same protein. P-28 and, by implication, v-28 suffice to endow the bacterial RNA polymerase core with a novel transcription specificity.

Ammonium Sulfate↗