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Biomedical subjects

J W Brown

Publications and source records attributed to J W Brown.

At least 19 recordsLinked to original sources
PubMed1992

Characterization and expression of U1snRNA genes from potato.

U1 small nuclear RNAs (U1snRNAs) occur in the nucleus of plants and animals where, complexed with several proteins in the form of U1 small nuclear ribonucleoprotein particles (U1snRNPs), they play an important role in precursor messenger RNA (pre-mRNA) splicing. Ten potato U1snRNA genes have been isolated on two genomic clones illustrating the clustering of this multigene family on the potato genome. Based on both the sequence of their coding regions and upstream regulatory elements, seven of the genes are potentially functional. The other three genes were pseudogenes with defective promoter or coding region sequences. Analysis of expression of individual cloned U1snRNA genes in transfected tobacco protoplasts was impossible due to the similarity of U1snRNA sequences in tobacco. However, by marking the coding regions with oligonucleotides or constructing chimaeric genes consisting of a potato U1snRNA promoter region and maize U5snRNA coding region, three of the U1 promoter regions were shown to be transcriptionally active.

Base Sequence↗
PubMed1992

The use of bronchotomy and retrograde dilatation to repair acquired obliterative bronchial obstruction.

A case is presented of acquired obliterative mainstem bronchial obstruction with total ipsilateral lung atelectasis and contralateral lung hyperexpansion. The condition failed to improve after a suitable trial of positive airway pressure and medical management. Penetration of the obstructing lesion bia bronchotomy and a distal retrograde approach successfully opened the airway and the patient has been symptom-free for more than 9 months. This unique approach may be useful in other selected patients with similar acquired lesions.

Airway Obstruction↗
PubMed1992

Phrenological studies of aphasia before Broca: Broca's aphasia or Gall's aphasia?

The history of aphasia is usually taken to begin with Broca's (1861a,b) discovery of the correlation of aphemia with damage to the posterior inferior portion of the frontal lobes and the subsequent relation to left hemisphere. That there were prior, even biblical, references to aphasia is not in dispute, nor that, according to Benton and Joynt (1960), almost all the clinical forms of aphasia had been described prior to 1800. The significance of Broca's case studies, therefore, lies in the association of motor aphasia with focal pathology in the frontal lobe. This paper examines the status of aphasia localization prior to Broca, and, specifically, the extent to which Broca's discovery may have been anticipated by the phrenologists.

Aphasia, Broca↗
PubMed1992

The varieties of ribonuclease P.

Ribonuclease P is a ribozyme involved in tRNA processing that is present in all cells and organelles that synthesize tRNA. Most of our understanding of ribonuclease P derives from studies of the bacterial enzyme. This enzyme has been characterized biochemically and a secondary structure for the RNA subunit has been proposed. Isolation and characterization of ribonuclease P from diverse Archaea and Eukarya are now modifying and adding to our model of this unusual enzyme. The latter instances of RNase P differ from the bacterial version, but similarities are emerging.

Animals↗
PubMed1992

Surgery for atrioventricular node reentry tachycardia. Results with surgical skeletonization of the atrioventricular node and discrete perinodal cryosurgery.

Surgical treatment options for interruption of atrioventricular node reentrant tachycardia include (1) skeletonization of the atrioventricular node by dissecting it from most of its atrial inputs and (2) discrete cryosurgery of the perinodal tissues by applying a series of sequential cryolesions to the atrial tissues immediately adjacent to the atrioventricular node. Both these techniques attempt to interrupt one of the dual atrioventricular node conduction pathways while preserving the other. This report describes 17 consecutive patients who underwent surgical treatment, 10 patients with skeletonization of the atrioventricular node and seven patients with discrete perinodal cryosurgery. There were 10 female and seven male patients and their ages ranged from 28 to 56 years (mean 38). Two of the 17 patients had Wolff-Parkinson-White syndrome and their accessory pathways were interrupted before the atrioventricular nodal reentrant tachycardia was ablated. All the procedures were performed in a normothermic beating heart while atrioventricular conduction was monitored closely. In the skeletonization technique, the right atrial septum was mobilized and the atrioventricular node exposed anterior to the tendon of the Todaro. The perinodal cryosurgical procedure was also performed through a right atriotomy and a series of sequential 3 mm cryolesions were placed around the borders of the triangle of Koch on the inferior right atrial septum. There were no operative deaths. Two patients who underwent the skeletonization operation had heart block necessitating pacemaker therapy. At postoperative electrophysiologic study, no echoes or atrioventricular nodal reentrant tachycardia were inducible in any of the 17 patients. All patients have remained free of arrhythmia recurrence and have required no antiarrhythmic therapy after a follow-up of 5 to 28 months (mean 14). In conclusion, both atrioventricular node skeletonization and perinodal cryosurgery successfully ablate atrioventricular nodal reentrant tachycardia; however, perinodal cryosurgery appears to be safer in avoiding heart block, is more easily performed, and is our procedure of choice for the management of medically refractory atrioventricular nodal reentrant tachycardia.

Adolescent↗
PubMed1979

Differential tolerance to dietary amino acid-induced changes in aggressive behavior and locomotor activity in mice.

Male albino mice were maintained on a semisynthetic 12% casein protein diet for 2 weeks, then switched to diets modified by the addition of a 4% L-amino acid supplement (L-tyrosine, L-phenylalanine, and L-tryptophan) or 4% casein (control). Territorial=induced aggressive behavior increased following 1 week on the amino acid supplements, especially after tyrosine, but an apparent tolerance developed to these effects after 5 weeks on the amino acid supplements. Locomotor activity also increased following 1 week on the supplements, most notably after phenylalanine alone or in combination with tyrosine, and these effects tended to persist after 5 weeks on the supplements. Endogenous whole brain levels of dopamine, norepinephrine, serotonin, 5-hydroxyindoleacetic acid, tyrosine, phenylalanine, and tryptophan showed no tolerance to increased concentrations of brain catecholamines and indoleamines over the 5-week period, and no clear relation between the concentrations of these monoamines and the behavioral changes.

Aggression↗