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Biomedical subjects

D Carroll

Publications and source records attributed to D Carroll.

At least 253 records · Page 14Linked to original sources
PubMed1976

Adjacent repeating units of Xenopus laevis 5S DNA can be heterogeneous in length.

The distribution of length heterogeneity in adjacent repeating units of X. laevis 5S DNA has been examined by "cloning" 5S DNA in bacteria. Fragments of 5S DNA produced by partial digestion with Hind III and containing 1, 4, and 5 repeating units have been inserted at the single Hind III site of the tetracycline-resistance plasmid, pSC101, and the hybrid plasmids cloned in E. coli. Adjacent 5S DNA repeats in the cloned multi-repeat fragments can differ in length. This finding rules out some mechanisms which have been proposed to account for the parallel evolution of tandem repeated DNAs. The results are consistent with an unequal crossing-over mechanism and place some constraints on the molecular processes in this recombinatory event.

Animals↗
PubMed1976

The electrodermal component of the orienting response in blind and deaf individuals.

Skin conductance response (SCR) was monitored as an index of the orienting response (OR) to a series of 20 tones presented to blind and sighted schoolchildren. Blind children showed fewer criterion SCRs than sighted children, and significantly more of the blind sample exhibited SCR habituation. The blind group also demonstrated fewer non-specific SCRs than sighted control subjects, but demonstrated a higher average skin conductance level (SCL). A second experiment found similar effects for deaf versus hearing children presented with simple visual stimulation, save that no significant difference was observed between these groups in SCL. These results can be explained by assuming that loss of modality results in more efficient development of a neuronal model of the salient features of stimuli impinging on the remaining intact modalities. An explanation in terms of the assessed significance of the stimulus situation can also be entertained. The atypical skin conductance activity of three of the blind group was given separate consideration.

Acoustic Stimulation↗
PubMed1975

Hemoptysis.

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Adult↗
PubMed1975

Pickwickian syndrome, 20 years later.

The Pickwickian Syndrome stimulated new pathophysiological concepts in regard to control of ventilation. With the advent of sleep laboratories, the peculiar sleep apnea occurring in some of these patients has been explained on the basis of intermittent upper airway obstruction. Two patients with different manifestations of the Pickwickian Syndrome are presented. The suggestion is made that these two subsyndromes should have unique designations. The Auchincloss Syndrome is manifested by right heart failure and respiratory acidosis in obese patients who are alert and have no major abnormality of breathing pattern. The fundamental cause of this abnormality is the increased work of breathing caused by the obesity. The cost of breathing is so high that the ventilatory regulation is compromised and respiratory acidosis results. The Gastaut Syndrome is characterized principally by hypersomnia and sleep apnea. The fundamental defect is upper airway obstruction during sleep, resulting in increased work of breathing, which together with the increased work caused by obesity leads to respiratory acidosis and right ventricular failure. Hypersomnia, rather than heart failure or respiratory acidosis, is the major manifestation of this syndrome, and is the result of sleep loss.

Acidosis, Respiratory↗
PubMed1975

Intraocular irrigating solutions for clinical vitrectomy.

Two different intraocular irrigating solutions were used during pars plana vitrectomy. Use of glutathione-bicarbonate-Ringer's (GBR) solution resulted in significantly fewer corneal complications and less endothelial damage when compared to lactated Ringer's solution. The visual results were disappointing.

Bicarbonates↗
PubMed1974

Amplified ribosomal DNA from Xenopus laevis has heterogeneous spacer lengths.

Eco R(1) restriction endonuclease makes two cuts in each repeating unit of amplified ribosomal DNA (rDNA) from Xenopus laevis. The locations of these cuts have been established by comparison of the secondary structure of single-stranded Eco R(1) fragments (as visualized in the electron microscope) with that of X. laevis rRNAs and of long strands of uncut rDNA. Of the two classes of fragments generated, the smaller one contains 90% of the 28S rRNA gene, has a duplex molecular weight of 3.0 x 10(6) and is homogeneous in size. The larger class of molecules contains 80% of the 18S rRNA gene and all of the nontranscribed spacer. These latter fragments are heterogeneous with molecular weights ranging from 4.0 to 5.9 x 10(6). The distribution of sizes within the large class of fragments varies among different preparations of rDNA, and heterogeneity is present in the DNA amplified from the rDNA of a single nucleolar organizer. The heterogeneity is located in the nontranscribed spacer region which is variable in length. This has been demonstrated by the formation of deletion loops in heteroduplexes made between larger fragments of different lengths.

Animals↗