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Biomedical subjects

J Plummer

Publications and source records attributed to J Plummer.

32 records · Page 2Linked to original sources
PubMed1991

The Lurcher cerebellar mutant phenotype is not expressed on a staggerer mutant background.

The hierarchy of the various processes responsible for the development of the complex, elaborated Purkinje cell can be examined by taking advantage of a series of spontaneous mutations that affect cerebellar development in the mouse. This study uses double mutants containing genes for two separate hereditary cerebellar mutations that have been shown to act intrinsically in Purkinje cells in order to investigate the time course and modes of action of these mutations. Lurcher mice show 100% degeneration of Purkinje cells, starting during the second postnatal week, while staggerer mice show reduced numbers of Purkinje cells in a distinctive mediolateral distribution from the time of birth, with the remainder grossly stunted. When these mutations are combined genetically, mice shown by progeny tests to harbor both staggerer and Lurcher genotypes exhibit staggerer-like behavior and overall cerebellar morphology; they also do not lose 100% of their Purkinje cells, as Lurcher mutants would otherwise do. Instead, they show a characteristic staggerer cerebellar pathology. We conclude that the intrinsic action of the staggerer gene in Purkinje cells occurs earlier in development than do effects of the Lurcher gene, and that the action of the staggerer gene prevents Purkinje cells from acquiring the characteristics required for the cytotoxic action of the Lurcher gene.

Animals↗
PubMed1985

A comparative assessment of lactate dehydrogenase isozymes, LDHk and LDH5.

An apparently unique isozyme of lactate dehydrogenase has been reported associated with transformation by Kirsten sarcoma virus, which was also expressed in human cancer. This isozyme was designated LDHk (Anderson, G.R., and Kovacik, W.P., Jr., (1981) Proc. Natl. Acad. Sci. U.S.A. 78, 3209-3213; Anderson, G. R., Kovacik, W. P., Jr., and Marotti, K. R. (1981) J. Biol. Chem. 256, 10583-10591). However, preparations of LDH5 from human placenta and from HeLa cells were later shown to exhibit some of the properties ascribed to LDHk9 and the identify of LDHk as a unique isozyme was questioned (Morin, M. E., and Hance, A. J., (1983) J. Biol. Chem. 258, 2864-2869). Saavadra and Anderson (Saavedra, R. A., and Anderson, G. R. (1983) Science (Wash. D.C.) 221, 291-292) refuted the arguments of Morin and Hance (Morin, M. E., and Hance, A. J. (1983) J. Biol. Chem. 258, 2864-2869) by claiming that commercial preparations of human placental LDH5 were contaminated with LDHk. Re-evaluation of the unique properties which distinguish LDHk from conventional LDH5 indicates that the two isozymes may not be different. Highly purified preparations of LDHk exhibit a single Mr = 34,000 polypeptide subunit on sodium dodecyl sulfate-acrylamide gels, yet retain activity detectable as both LDHk and LDH5. Attempts to separate LDHk and LDH5 by column chromatography or by continuous electrophoresis on a variety of solid support matrices were unsuccessful. Enzyme activity identified as LDHk in imidazole-borate-buffered gels migrating toward the cathode was detected as LDH5 activity on re-electrophoresis. LDH5 activity identified by electrophoretic migration toward the anode in Tris-glycine-buffered gels also recorded as LDHk when re-electrophoresed toward the cathode in imidazole-borate-buffered gels. Quantitative assays of enzyme activity recovered from the two-gel assay systems, as well as re-electrophoresis of isozyme-enriched preparations, indicated that cross-contamination of isozymes was not responsible for the results obtained.

Animals↗
PubMed1980

Restriction fragment primed phi X174 single-stranded DNA as template for DNA polymerase alpha and beta. Detection and partial purification of a polymerase alpha stimulating factor.

Template-primers constructed of phiX174 single-stranded viral DNA hybridized to a restriction fragment of phiX174 RF DNA can be used for extensive polymerization by DNA polymerase alpha. Polymerization is dependent upon a restriction fragment containing a 3'OH. The products of the reaction have been identified by agarose gel electrophoresis. Polymerization of 150--400 nucleotides can be obtained in 1h depending upon the restriction fragment used as primer. Synthesis may be limited by barriers in the primary or secondary structure of the template. A factor which stimulates the rate of alpha polymerase activity on these templates was partially purified. This factor does not stimulate alpha polymerase on activated DNA. The stimulating factor sediments at 5.5 S in glycerol gradients containing 0.4M potassium phosphate and has an apparent molecular weight of 70 000 on Sephadex G-100.

Animals↗
PubMed1979

Double blind controlled comparison of aspirin, allopurinol and placebo in the management of arthralgia during pyrazinamide administration.

Chinese patients with arthralgia during treatment with an antituberculosis regimen containing pyrazinamide were allocated at random to 3 anti-arthralgia treatment series in a controlled double-blind study. One series (18 patients) received soluble aspirin 2.4 g daily, the second (23 patients) allopurinol 200 mg daily, and the third (19 patients) placebo only, for 8 weeks. The response was assessed both by independent assessors and by the patients themselves using a diary card. The serum uric acid concentration was measured before and during anti-arthralgia treatment. The joints most commonly affected were the shoulders, the knees and the fingers, and symptoms and signs were in general neither severe nor protracted. For most of the patients in all 3 series the joint symptoms and signs improved during the 8 weeks, but a higher proportion of patients in the aspirin and placebo series than in the allopurinol series experienced improvement, this being most rapid in the aspirin series. Only in the aspirin series was the mean serum uric acid concentration lower during treatment than before it, and this effect was related to the dose in mg per kg. It is concluded that the arthralgia was often self-limiting, that aspirin had a small beneficial effect, that allopurinol, in the dosage studied, may have had a slightly deleterious effect, but that it would be worth studying larger dosages of allopurinol because the dosage studied did not affect the serum uric acid concentration.

Adolescent↗
PubMed1978

Chlamydomonas flagellar mutants lacking radial spokes and central tubules. Structure, composition, and function of specific axonemal components.

The fine structure, protein composition, and roles in flagellar movement of specific axonemal components were studied in wild-type Chlamydomonas and paralyzed mutants pf-14, pf-15A, and pf-19. Electron microscope examination of the isolated axoneme of pf-14 showed that it lacks the radial spokes but is otherwise structurally normal. Comparison of isolated axonemes of wild type and pf-14 by sodium dodecyl sulfate-acrylamide gel electrophoresis indicated that the mutant is missing a protein of 118,000 mol wt; this protein is apparently a major component of the spokes. Pf-15A and pf-19 lack the central tubules and sheath; axonemes of these mutants are missing three high molecular weight proteins which are probably components of the central tubule-central sheath complex. Under conditions where wild-type axonemes reactivated, axonemes of the three mutants remained intact but did not form bends. However, mutant and wild-type axonemes underwent identical adenosine triphosphate-induced disintegration after treatment with trypsin; the dynein arms of the mutants are therefore capable of generating interdoublet shearing forces. These findings indicated that both the radial spokes and the central tubule-central sheath complex are essential for conversion of interdoublet sliding into axonemal bending. Moreover, because axonemes of pf-14 remained intact under reactivating conditions, the nexin links alone are sufficient to limit the amount of interdoublet sliding that occurs. The axial periodicities of the central sheath, dynein arms, radial spokes, and nexin links of Chlamydomonas were determined by electron microscopy using the lattice-spacing of crystalline catalase as an internal standard. Some new ultrastructural details of the components are described.

Adenosine Triphosphate↗
PubMedDate not supplied

An evaluation of epidural bupivacaine with and without meperidine in labor.

BACKGROUND: One aim of epidural analgesia during childbirth is to provide satisfactory pain relief with minimal side effects. We hypothesized that a combination of opioid and local anesthetic would better achieve this aim than either drug alone. This study compared the efficacy and side effects of epidural meperidine and bupivacaine combined to those of meperidine and bupivacaine alone. METHODS: One hundred consenting nulliparas requesting epidural analgesia in labor were randomly assigned to receive, in a double-blind fashion, one of five treatments. These were 25 mg meperidine, 12.5 mg bupivacaine, 25 mg meperidine plus 12.5 mg bupivacaine, 25 mg bupivacaine, and 37.5 mg bupivacaine. Efficacy of analgesia and side effects were assessed before and after each dose. Leg strength was measured with a force meter and blood flow to each foot with a blood perfusion monitor. The neurobehavioral state of the newborn was assessed by a pediatrician who was blind to treatment using a neurologic and adaptive capacity scoring system. RESULTS: Thirty-seven women did not achieve satisfactory analgesia after the first dose of test medication; these predominantly were those who received 25 mg meperidine (n = 12) or 12.5 mg bupivacaine (n = 11). Nausea decreased after the initial dose with all treatments (p less than 0.01), whereas shivering increased in patients receiving bupivacaine (p less than 0.01). There was a reduction in leg strength and an increase in blood flow associated with the two higher bupivacaine treatments (p less than 0.01), and with both parameters the dependent limb was most affected. Overall patient satisfaction was greatest in the group receiving meperidine plus bupivacaine. Neonatal neurologic and adaptive capacity scores did not differ significantly among the treatment groups. CONCLUSION: The low-dose combination of meperidine and bupivacaine used in this trial proved a satisfactory preparation for epidural administration during the early stages of labor.

Adult↗