Mechanical properties of porcine intralobar pulmonary arteries

The isobaric and isovolumetric properties of intrapulmonary arteries were evaluated by placing a highly compliant balloon inside arterial segments. The passive pressure-volume (P-V) curve was obtained by changing volume (0.004 ml/s) and measuring pressure. The isobaric active volume change (delta V) or isovolumetric active pressure change (delta P) generated by submaximal histamine was measured at four different transmural pressures (Ptm's) reached by balloon inflation. The maximal delta P = 11.2 +/- 0.6 cmH2O (mean +/- SE) was achieved at 30.8 +/- 1.2 cmH2O Ptm and maximal delta V = 0.20 +/- 0.02 ml at 16.7 +/- 1.7 cmH2O Ptm. The P-V relationships were similar when volume was increased after either isobaric or isovolumetric contraction. The calculated length-tension (L-T) relationship showed that the active tension curve was relatively flat and that the passive tension at the optimal length was 149 +/- 11% of maximal active tension. These data show that 1) a large elastic component operates in parallel with the smooth muscle in intralobar pulmonary arteries, and 2) the change in resistance associated with vascular expansion of the proximal arteries is independent of the type of contraction that occurs in the more distal arterial segments.     

Synergism of cortisol and thyrotropin-releasing hormone in lung maturation in fetal sheep

The effects of fetal infusions of cortisol and thyrotropin-releasing hormone (TRH) singly and together on pressure-volume relationships and saturated phosphatidylcholine (SPC) concentrations in the lungs were studied in 28 fetal sheep delivered at 128 days of gestation. Four groups each of 7 fetuses were infused with either saline (for 156 h), TRH (25 micrograms/h in 60-s pulses for 156 h), TRH (for 156 h) combined with cortisol (1 mg/h for 84 h), or cortisol (for 84 h). Cortisol had no effect on SPC concentrations, whereas both TRH and cortisol plus TRH increased the concentration of SPC in lavage fluid but not lung tissue. Neither cortisol nor TRH significantly affected lung distensibility [V40; 0.64 +/- 0.04 and 0.57 +/- 0.10 (SE) ml/g, respectively, vs. 0.41 +/- 0.03 ml/g in controls] or stability (V5; 0.24 +/- 0.01 and 0.35 +/- 0.07 ml/g vs. 0.24 +/- 0.03 ml/g), whereas treatment with a combination of the two hormones was associated with a fourfold increase in V40 (1.70 +/- 0.16 ml/g) and V5 (1.03 +/- 0.15 ml/g). Since raised concentrations of cortisol, triiodothyronine, and estradiol-17 beta (treatment with cortisol) had no effect on V40 and V5, whereas similar hormonal changes associated with elevated prolactin levels (treatment with cortisol plus TRH) had marked effects, we conclude that prolactin plays an essential part in the synergism of cortisol and TRH.     

Formation of methyl ester of 2-methylglyceric acid from thymine glycol residues: a convenient new method for determining radiation damage to DNA

Thymine glycol residues in DNA or thymidine were converted to methyl 2-methylglycerate by reaction with alkaline borohydride followed by methanolic HCl. The product was labeled either from [3H]DNA or from [3H]borohydride and was followed by cochromatography with authentic 14C-labeled material. Following acid hydrolysis, the identity of 2-methylglyceric acid was confirmed by high-resolution mass spectrometry, NMR, IR, and elemental analysis. Treatment of DNA or thymidine with X-irradiation, with H2O2 and Fe2+, with H2O2, Cu2+, and ascorbate, and with H2O2 and ultraviolet light, permanganate, or sonication all produced methyl 2-methylglycerate in varying amounts after alkaline borohydride and methanolic HCl, whereas untreated DNA did not. The data indicate that certain oxidants including hydroxyl radicals generated by chemical means or from radiolysis of water convert thymine residues to thymine glycols in DNA, which can be determined as methyl 2-methylglycerate.     

Histamine releases PGI2 from human pulmonary artery

Histamine caused a triphasic response of human pulmonary artery strips in vitro, consisting of a small initial contraction followed by pronounced relaxation preceding a second contractile response. These characteristics were not seen with other contractile stimuli including 5-hdyroxytryptamine, leukotriene D₄, and KC1. The relaxant component of this response was ablated by removal of endothelium from the vascular strips or by pretreatment of the tissues with 1μM indomethacin. Measurement of the PGI₂ degradation product 6-keto-PGF_1α in supernatants from histamine-challenged tissues confirmed the synthesis of PGI₂. Supernatants from unstimulated or leukotriene-challenged tissues contained no detectable amounts of 6-keto-PGF_1α. The histamine H₁ antagonist diphenhydramine inhibited both the contractile and relaxant responses to histamine whereas the H₂ antagonist cimetidine affected neither component. The released PGI₂ significantly altered the dose-respons curve to histamine without inhibiting the maximal contractile responses. We conclude that histamine induces PGI₂ formation from pulmonary arterial endothelium via an H₁ receptor.     

The effects of ACTH1-24 or cortisol on pulmonary maturation in the adrenalectomized ovine fetus

Pulmonary maturation in 8 ovine fetuses bilaterally adrenalectomized at 98-101 days and infused at term with either ACTH1-24 or cortisol was compared with that in 4 untreated sham-operated controls. Four of the adrenalectomized fetuses were infused intravascularly with ACTH1-24 5 micrograms/h for 84 h before delivery and the other four were infused with cortisol 1 mg/h for 72 h. The high plasma concentrations of immunoreactive ACTH in the adrenalectomized fetuses (2762 +/- 1339 ng/l, mean +/- SD) were not significantly elevated by infusion of ACTH1-24 but were markedly depressed by infusion of cortisol. Distensibility (V40) of the lungs was less than that of controls in both the ACTH1-24-infused and cortisol-infused fetuses (1.86 +/- 0.31 ml/g vs 0.62 +/- 0.13 ml/g and 1.27 +/- 0.34 ml/g respectively) but it was significantly greater in the cortisol-infused fetuses compared to those infused with ACTH1-24. The volume of air retained at 5 cm H2O pressure (V5) during deflation was markedly reduced in adrenalectomized fetuses (controls 1.14 +/- 0.52 ml/g vs 0.25 +/- 0.25 ml/g and 0.12 +/- 0.6 ml/g). The wet weight of the lungs and the concentrations of saturated phosphatylcholine in lung tissue and lavage fluid were lower in the adrenalectomized fetuses than in controls but the differences were not significant. It is concluded that infusion of ACTH1-24 at term in adrenalectomized fetuses is probably without effect whereas cortisol enhances distensibility.     

Increased in vitro responses of tracheal smooth muscle from hyperresponsive guinea pigs

Repeated aerosol antigen challenge of previously sensitized guinea pigs induces airway hyperresponsiveness to inhaled acetylcholine. To determine the mechanism producing these airway changes and assuming that changes in the trachealis muscle reflect changes in muscle of the entire tracheobronchial tree, we examined the in vitro smooth muscle mechanics and morphometric parameters of tracheae from guinea pigs demonstrating hyperresponsiveness in vivo vs. tracheae from control guinea pigs. No differences between these groups were found in luminal volume at zero transmural pressure, passive pressure-volume characteristics, or area of airway wall. Smooth muscle areas were slightly less in tracheae from hyperresponsive guinea pigs. Tracheae from hyperresponsive guinea pigs had both significantly increased isovolumetric force generation and isobaric shortening compared with tracheae from controls when evaluated over the range of transmural pressures from -40 to 40 cmH2O. We conclude that the in vivo airway hyperresponsiveness induced with repeated antigen challenge is associated with both increased force generation and shortening of tracheal smooth muscle without increased muscle mass, suggesting enhanced contractile activity.     

Chromosome 14 and late-onset familial Alzheimer disease (FAD)

Familial Alzheimer disease (FAD) is genetically heterogeneous. Two loci responsible for early-onset FAD have been identified: the amyloid precursor protein gene on chromosome 21 and the as-yet-unidentified locus on chromosome 14. The genetics of late-onset FAD is unresolved. Maximum-likelihood, affected-pedigree-member (APM), and sib-pair analyses were used, in 49 families with a mean age at onset ≥60 years, to determine whether the chromosome 14 locus is responsible for late-onset FAD. The markers used were D14S53, D14S43, and D14S52. The LOD score method was used to test for linkage of late-onset FAD to the chromosome 14 markers, under three different models: age-dependent penetrance, an affected-only analysis, and age-dependent penetrance with allowance for possible age-dependent sporadic cases. No evidence for linkage was obtained under any of these conditions for the late-onset kindreds, and strong evidence against linkage (LOD score ≤ –2.0) to this region was obtained. Heterogeneity tests of the LOD score results for the combined group of families (early onset, Volga Germans, and late onset) favored the hypothesis of linkage to chromosome 14 with genetic heterogeneity. The positive results are primarily from early-onset families. APM analysis gave significant evidence for linkage of D14S43 and D14S52 to FAD in early-onset kindreds (P < .02). No evidence for linkage was found for the entire late-onset family group. Significant evidence for linkage to D14S52, however, was found for a subgroup of families of intermediate age at onset (mean age at onset ≥60 years and <70 years). These results indicate that the chromosome 14 locus is not responsible for Alzheimer disease in most late-onset FAD kindreds but could play a role in a subset of these kindreds.     

Cladistic analysis of the Cirripedia Thoracica

We present a cladistic analysis of the Cirripedia Thoracica using morphological characters and the Acrothoracica and Ascothoracida as outgroups. The list of characters comprised 32 shell and soft body features. The operational taxonomic units (OTUs) comprised 26 well-studied fossil and extant taxa, principally genera, since uncertainty about monophyly exists for most higher ranking taxonomic units. Parsimony analyses using PAUP 3.1.1 and Hennig86 produced 189 trees of assured minimal length. We also examined character evolution in the consensus trees using MacClade and Clados. The monophyly of the Balanomorpha and the Verrucomorpha sensu stricto is confirmed, and all trees featured a sister group relationship between the ‘living fossil Neoverruca and me Brachylepadomorpha. In the consensus trees the sequential progression of ‘pedunculate‘sister groups up to a node containing Neolepas also conforms to current views, but certain well-established taxa based solely on plesiomorphies stand out as paraphyletic, such as Pedunculata (= Lepadomorpha); Eolepadinae, Scalpellomorpha and Chthamaloidea. The 189 trees differed principally in the position of shell-less pedunculates, Neoverruca, the scalpelloid Capitulum, and the interrelationships within the Balanomorpha, although the 50% majority rule consensus tree almost fully resolved the latter. A monophyletic Sessilia comprising both Verrucomorpha and Balanomorpha appeared among the shortest trees, but not in the consensus. A tree with a monophyletic Verrucomorpha including Neoverruca had a tree length two steps longer than the consensus trees. Deletion of all extinct OTUs produced a radically different tree, which highlights the importance of fossils in estimating cirripede phylogeny. Mapping of our character set onto a manually constructed cladogram reflecting die most recent scenario of cirripede evolution resulted in a tree length five steps longer than any of our shortest trees. Our analysis reveals that several key questions in cirripede phylogeny remain unsolved, notably the position of shell-less forms and the transition from ‘pedunculate‘to ‘sessile‘barnacles. The inclusion of more fossil species at this point in our understanding of cirripede phylogeny will only result in even greater levels of uncertainty. When constructing the character list we also identified numerous uncertainties in the homology of traits commonly used in discussing cirripede evolution. Our study highlights larval ultrastructure, detailed studies of early ontogeny, and molecular data as the most promising areas for future research.     

In vivo and in vitro correlation of trachealis muscle contraction in dogs.

Maximal trachealis muscle shortening in vivo was compared with that in vitro in seven anesthetized dogs. In addition, the effect of graded elastic loads on the muscle was evaluated in vitro. In vivo trachealis muscle shortening, as measured using sonomicrometry, revealed maximal active shortening to be 28.8 +/- 11.7% (SD) of initial length. Trachealis muscle preparations from the same animals were studied in vitro to evaluate isometric force generation, isotonic shortening, and the effect of applying linear elastic loads to the trachealis muscle during contraction from optimal length. Maximal isotonic shortening was 66.8 +/- 8.4% of optimal length in vitro. Increasing elastic loads decreased active shortening and velocity of shortening in vitro in a hyperbolic manner. The elastic load required to decrease in vitro shortening to the extent of the shortening observed in vivo was similar to the estimated load provided by the tracheal cartilage. We conclude that decreased active shortening in vivo is primarily due to the elastic afterload provided by cartilage.     

Concomitant loss of cell surface fibronectin and laminin from transformed rat kidney cells

Both fibronectin and laminin were found by immunofluorescence as a matrix at the surface of normal rat kidney cells. These matrices were absent from the surface of virally transformed rat kidney cells. Soluble fibronectin and laminin were detected in the culture media of the transformed as well as the normal cells. Culture supernates of the transformed cells contained even more fibronectin than the supernates of the transformed cells contained even more fibronectin than the supernates of the normal cells while laminin was present in similar amounts in both culture media. This shows that the loss of fibronectin and laminin from the surface of the transformed cells is caused by failure of the cells to deposit these proteins into an insoluble matrix and not caused by inadequate production. Fibronectins isolated from culture media of the normal and transformed cells were similar in SDS polyacrylamide gel electrophresis. Laminin isolated from culture media by affinity chromatography on heparin-Sepharose followed by immunoprecipitation was composed of three main polypeptides, one with a molecular weight of 400,000 and two with a molecular weight close to 200,000 in both cell types. Fibronectins from both cell types were equally active in promoting cell attachment. Rat fibronectin from transformed cells, like normal cells, when applied to culture dishes coated with fibronectin, readily attached and spread on the substratum, requiring approximately the same amount of fibronectin as the normal cells. On the basis of these results it seem that the failure of the transformed cells to incorporate fibronectin into an insoluble cell surface matix is not a consequence of a demonstrable change in the functional characteristics of the fibronectin molecule or in the ability of the cells to interact with fibronectin. It may depend on as yet unidentified interactions of the cell surface. Similar interactions may be needed for the deposition of laminin into the matrix, because laminin was also absent from the surface of transformed cells, despite its being synthesized by these cells.