Pulmonary prostacyclin synthase overexpression in transgenic mice protects against development of hypoxic pulmonary hypertension.

Prostacyclin synthase (PGIS) is the final committed enzyme in the metabolic pathway leading to prostacyclin (PGI2) production. Patients with severe pulmonary hypertension have a PGIS deficiency of their precapillary vessels, but the importance of this deficiency for lung vascular remodeling remains unclear. We hypothesized that selective pulmonary overexpression of PGIS may prevent the development of pulmonary hypertension. To study this hypothesis, transgenic mice were created with selective pulmonary PGIS overexpression using a construct of the 3.7-kb human surfactant protein-C (SP-C) promoter and the rat PGIS cDNA. Transgenic mice (Tg+) and nontransgenic littermates (Tg-) were subjected to a simulated altitude of 17,000 ft for 5 weeks, and right ventricular systolic pressure (RVSP) was measured. Histology was performed on the lungs. The Tg+ mice produced 2-fold more pulmonary 6-keto prostaglandin F1alpha (PGF1alpha) levels than did Tg- mice. After exposure to chronic hypobaric hypoxia, Tg+ mice have lower RVSP than do Tg- mice. Histologic examination of the lungs revealed nearly normal arteriolar vessels in the Tg+ mice in comparison with vessel wall hypertrophy in the Tg- mice. These studies demonstrate that Tg+ mice were protected from the development of pulmonary hypertension after exposure to chronic hypobaric hypoxia. We conclude that PGIS plays a major role in modifying the pulmonary vascular response to chronic hypoxia. This has important implications for the pathogenesis and treatment of severe pulmonary hypertension.

Visual-neural correlate of speechreading ability in normal-hearing adults: reliability.

In 1977, Shepherd and colleagues reported significant correlations (-.90, -.91) between speechreading scores and the latency of a selected negative peak (VN130 measure) on the averaged visual electroencephalic wave form. The primary purpose of this current study was to examine the stability, or repeatability, of this relation between these cognitive and neurophysiologic measures over a period of several months and thus support its test-retest reliability. Repeated speechreading word and sentence scores were gathered during three test-retest sessions from each of 20 normal-hearing adults. An average of 56 days occurred from the end of one to the beginning of another speechreading sessions. During each of four other test-retest sessions, averaged visual electroencephalic responses (AVERs) were evoked from each subject. An average of 49 days intervened between AVER sessions. Product-moment correlations computed among repeated word scores and VN130 measures ranged from -.61 to -.89. Based on these findings, it was concluded that the VN130 measure of visual neural firing time is a reliable correlate of speechreading in normal-hearing adults.

Visual-neural correlate of speechreading ability in normal-hearing adults.

Significant product-moment correlations ranging from -0.90 to -0.91 were computed between a selected peak-latency in average visual electroencephalic responses and speechreading scores. Subjects were 20 adults with normal hearing and assumed normal vision who had had no formal training in the speechreading process. The negative peak selected as this study's measure of visual-neural firing time occurs at an average of 130 msec from stimulus-onset in average visual electronencephalic responses evoked from either the right or left side of the head of normal adults. Speechreading measures included word and sentence scores obtained using a videotape of a female speaker presenting the 31 sentences that appear in the Utley Sentence Test of Lipreading Ability, Form B.

The semantic structure in deaf children.

The investigation proposed to qualify the semantic structure of the language of 33 deaf children utilizing the semantic differential procedure. The ratings of the deaf children were analyzed using factor analysis. The results revealed that the semantic system of the deaf children contained the Evaluation and Potency dimensions evident in the semantic systems of normal hearing children as reported by DiVesta (1966). Several other factors reliably demonstrated by others to be included in the meaning systems of normal hearing children, however, were not evident in the meaning systems of these deaf children.