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Biomedical subjects

J G Howe

Publications and source records attributed to J G Howe.

50 records · Page 3Linked to original sources
PubMed1982

A study of the role of the cholinergic system in amygdaloid kindling in rats.

The effect of atropine on kindling the amygdala of rats was tested by administering the drug in a dose of 25 mg/kg 1 h before each stimulus was applied. Rats tested with atropine kindled at the same rate as saline-treated controls. Cholinergic activity in the amygdala of rats was assessed, 4 weeks after the completion of kindling, by measuring both muscarinic receptor numbers and sodium-dependent high affinity choline uptake in tissue homogenates. There was no change in either of these parameters attributable to kindling. These results suggest that changes in the cholinergic system are not fundamental either to the development or the maintenance of kindling in the rat amygdala.

Acetylcholine↗
PubMed1982

Cloning and mapping of a gene for translational initiation factor IF2 in Escherichia coli.

A novel method, not relying on genetic complementation of a mutation, was used to clone a gene for translational initiation factor IF2. Two clones from a cosmid library of total Escherichia coli DNA were isolated for their ability to overproduce IF2 in vivo as determined by quantitative immunoblotting. "Maxicell" analysis of cosmid-encoded proteins and specific immune precipitation of the labeled proteins showed that the structural gene for IF2 (inf B) had been cloned. Subcloning fragments from the original cosmids located the inf B gene to a 4.8-kilobase pair HindIII/BamHI fragment. This fragment has been inserted into an integration-deficient recombinant lambda phage that lysogenizes by homology. By mapping the point of lysogenization on the E. coli chromosome, inf B has been located at 68 min, very close to argG, nusA, rpsO, and pnp. Because the gene for initiation factor IF3 is located at 38 min on the chromosome, the genes for translational initiation factors are not grouped together.

Bacteriophage lambda↗
PubMed1982

Expression of the gene for Escherichia coli initiation factor IE-3 in vivo and in vitro.

Expression of protein synthesis initiation factor IF-3 in vivo was studied by measuring its level in exponentially growing cells as a function of gene dosage. A strain haploid for infC, the gene for IF-3, was modified to carry one or two additional infC genes giving diploid and triploid strains. Polyploid strains were achieved by the presence of multicopy plasmids expressing the infC gene. When IF-3 levels were measured by quantitative immunoblotting they were found to be proportional to the gene dosage; the presence of a multicopy plasmid thus causes considerable overproduction of IF-3, enabling large quantities to be purified. When lysates were prepared from freshly grown cells, only IF-3 alpha (the long form) was detected; however when IF-3 was purified from a strain containing a multicopy plasmid which overproduced it, the major product found was IF-3 beta (the short form, lacking six amino acids from the N terminus). The synthesis of the two IF-3 forms was also studied by using a cell-free coupled transcription-translation system dependent on exogenous DNA: the IF-3 gene was found to be very efficiently expressed. IF-3 alpha increased more rapidly than IF-3 beta but following the cessation of protein synthesis IF-3 alpha decreased while IF-3 beta still increased. The results suggest that IF-3 alpha is slowly degraded to the beta form. Addition of non-radioactive IF-3 alpha, up to fivefold molar excess over ribosomes, to the synthesizing system in vitro did not inhibit IF-3 synthesis. Synthesis of IF-3 in vitro appears to be sensitive to guanosine 3'-diphosphate 5'-diphosphate.

Bacterial Proteins↗
PubMed1982

Lhermitte's sign in multiple sclerosis: a clinical survey and review of the literature.

Lhermitte's sign was experienced by 33.3% of 114 patients with multiple sclerosis, and in 16% it occurred in the first episode. Eleven patients with subacute combined degeneration of the cord due to pernicious anaemia also were reviewed, and one reported Lhermitte's sign. Review of the literature suggests that the symptom rarely occurs in other conditions except subacute combined degeneration of the cord, neck trauma, radiation myelitis and prolapsed cervical disc.

Adolescent↗
PubMed1981

A sensitive immunoblotting method for measuring protein synthesis initiation factor levels in lysates of Escherichia coli.

Protein synthesis initiation factor levels are measured in crude cell lysates of Escherichia coli MRE600 by use of a sensitive immunoblotting method. The method involves electrophoretic transfer of protein from sodium dodecyl sulfate-polyacrylamide gels onto nitrocellulose paper and subsequent incubation with a specific antiserum and radioactive iodinated second antibody. The measurement of iodinated antibody attached to known amounts of initiation factor is determined by densitometric scanning of autoradiographs or counting radioactivity in excised protein bands. Linear standard curves over the range 1 to 300 ng of factor are obtained by these methods. Unknown amounts of initiation factor in crude cell lysates are measured accurately; values agree with previous radioimmune assay data. The immunoblotting method serves as an alternative to the radioimmune assay in measuring small quantities of protein in complex mixtures. Immunoblotting enjoys three major advantages: it is simple and rapid to execute; it is sensitive; and it is capable of distinguishing multiple forms of the antigen which separate in the gel system employed.

Escherichia coli↗
PubMed1978

Anticonvulsants and thyroid function.

Serum total and free thyroid hormone concentrations were estimated in 42 patients with epilepsy taking anticonvulsants (phenytoin, phenobarbitone, and carbamazepine either singly or in combination). There was a significant reduction in total thyroxine (TT4), free thyroxine (FT4), and free triiodothyronine (FT3) in the treated group compared with controls. Free hormone concentrations were lower than total hormone concentrations, suggesting that increased clearance of thyroid hormones occurs in patients receiving anticonvulsants. Detailed analysis indicated that phenytoin had a significant depressant effect on TT4, FT4, FT3, and reverse T3 (rT3). Phenobarbitone and carbamazepine had no significant main effects, but there were significant interactions between phenytoin and carbamazepine for TT4 and FT4. phenobarbitone and carbamazepine for FT3, and phenytoin and phenobarbitone for rT3.

Adolescent↗
PubMedDate not supplied

Anterior cruciate ligament reconstruction using quadriceps patellar tendon graft. Part I. Long-term followup.

Eighty-three patients with ACL reconstructions using the quadriceps patellar tendon graft were evaluated in a 10 year (mean, 5.5 years) follow-up study. A five-part analysis, consisting of physical examination, questionnaire, Genucom analysis, operative note review, and radiographs, was performed. Seventy-six percent were categorized as satisfactory. Ninety-two percent were content with their results, while only 4% were unsatisfied. Ninety-three percent of the patients had no significant pain and 95% had no giving way postreconstruction. Ninety-two percent had no more than a mild functional deficit. Eighty-seven percent and 90% of the patients had no significant Lachman or pivot shift by examination, respectively. Our results showed no increase in failure over time (1 to 10 years), although those operated on during the initial 5 years showed more radiographic degenerative changes. Plotting our results in classification systems of other authors yielded success rates as good as or better than those using our own criteria. An objective means by which to quantify laxity did not reliably correlate with the quantifying of laxity made by physical examination. Only the lack of a formal rehabilitation program greater than 4 months postoperatively and repaired tears of the medial or lateral collateral ligaments proved to be significant risk factors for poor recovery.

Anterior Cruciate Ligament↗
PubMedDate not supplied

Anterior cruciate ligament reconstruction using quadriceps patellar tendon graft. Part II. A specific sport review.

Eighty-three patients, from a 10 year follow-up study, who underwent ACL reconstruction with a quadriceps patellar tendon graft were reviewed. A questionnaire qualifying their sports performance in 20 possible sports compared their preinjury status to postinjury and postreconstructive surgery. Successful and unsuccessful patients, as determined by our previous investigation, were likewise compared. Sports performance, regardless of the sport or level of competition, decreased substantially postinjury and then rose significantly to near but not equal to patient preinjury status. The most strenuous sports dipped to the lowest performance level after injury and returned with a correspondingly more modest gain after the reconstruction. Not surprisingly, successful patients had a more impressive return in performance than unsuccessful patients, mirroring their clinical grading. Of those deemed unsatisfactory (N = 20), graft failures were no worse off in performance rating than those that were classified as unsatisfactory because of persistent symptoms.

Anterior Cruciate Ligament↗