In vivo response of murine gamma delta T cells to a heat shock protein-derived peptide.

Recent results suggested that a large subset of heat shock protein HSP-60 reactive peripheral lymphoid gamma delta T cells preexists in normal adult mice, all members of which respond to a single segment of this common HSP. However, the experimental evidence supporting this idea involved in vitro peptide responses of gamma delta T-cell hybridomas generated from unprimed spleen cells. Here, we report an attempt to elicit a gamma delta T-cell response in vivo by stimulation of adult C57BL/10 mice with HSP-60 or an HSP-60-derived peptide fragment comprising amino acids 180-196 of mycobacterial HSP-60. Whereas no gamma delta T-cell response was detectable in mice injected with the intact protein, stimulation with the peptide altered the reactive gamma delta T-cell population in vivo. These changes were detected among hybridomas generated with cells restimulated in vitro and included a large increase in hybridizable gamma delta T cells, a nearly maximal increase in the relative frequency of HSP-60-reactive cells, and structural changes in expressed T-cell receptors of HSP-60-reactive cells. Interestingly, we failed to elicit a detectable alpha beta T-cell response to the particular peptide stimulatory for gamma delta T cells, although at least three other HSP-60 epitopes were recognized. Our data show that normal gamma delta T cells can respond in vivo to small peptide antigens. The gamma delta T-cell response to the HSP-60-derived peptide studied here is apparently independent of antigen-specific alpha beta T-cell reactivity.     

Osteoarthritis of the hip and Heberden''s nodes.

One hundred consecutive patients with proved osteoarthritis were assessed for the presence of terminal interphalangeal joint disease. There was a significant association found between the presence of Heberden's nodes and primary (axillary) arthritis. Secondary osteoarthritis was relatively free of nodal involvement. It is suggested that Heberden's nodes are a helpful clinical marker in differentiating between the two major groups of osteoarthritis.     

Impaired cell volume regulation in intestinal crypt epithelia of cystic fibrosis mice.

Cystic fibrosis is a disease characterized by abnormalities in the epithelia of the lungs, intestine, salivary and sweat glands, liver, and reproductive systems, often as a result of inadequate hydration of their secretions. The primary defect in cystic fibrosis is the altered activity of a cAMP-activated Cl- channel, the cystic fibrosis transmembrane conductance regulator (CFTR) channel. However, it is not clear how a defect in the CFTR Cl- channel function leads to the observed pathological changes. Although much is known about the structural properties and regulation of the CFTR, little is known of its relationship to cellular functions other than the cAMP-dependent Cl- secretion. Here we report that cell volume regulation after hypotonic challenge is also defective in intestinal crypt epithelial cells isolated from CFTR -/- mutant mice. Moreover, the impairment of the regulatory volume decrease in CFTR -/- crypts appears to be related to the inability of a K+ conductance to provide a pathway for the exit of this cation during the volume adjustments. This provides evidence that the lack of CFTR protein may have additional consequences for the cellular function other than the abnormal cAMP-mediated Cl- secretion.     

Specific and high-affinity binding of inositol phosphates to an isolated pleckstrin homology domain.

Pleckstrin homology (PH) domains are found in many signaling molecules and are thought to be involved in specific intermolecular interactions. Their binding to several proteins and to membranes containing 1-alpha-phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] has been reported. A region that includes the PH domain has also been implicated in binding of phospholipase C-delta 1 (PLC-delta 1) to both PtdIns(4,5)P2 and D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] [Cifuentes, M. E., Delaney, T. & Rebecchi, M. J. (1994) J. Biol. Chem. 269, 1945-1948]. We report herein that the isolated PH domain from PLC-delta 1 binds to both PtdIns(4,5)P2 and Ins(1,4,5)P3 with high affinity and shows the same binding specificity seen by others with whole PLC-delta 1. Thus the PH domain is functionally and structurally modular. These results demonstrate stereo-specific high-affinity binding by an isolated PH domain and further support a functional role for PH domains in the regulation of PLC isoforms. Other PH domains did not bind strongly to the compounds tested, suggesting that inositol phosphates and phospholipids are not likely physiological ligands for all PH domains. Nonetheless, since all PH-domain-containing proteins are associated with membrane surfaces, several PH domains bind to specific sites on membranes, and PH domains appear to be electrostatically polarized, a possible general role for PH domains in membrane association is suggested.     

Molecular phylogenetic inference from saber-toothed cat fossils of Rancho La Brea.

A method for the successful extraction of sequestered cellular DNA from 14,000-year-old fossil bones was developed and applied to asphalt-preserved specimens of the extinct saber-toothed cat, Smilodon fatalis. Two distinct gene segments, the mitochondrial gene for 12S rRNA and nuclear FLA-I (the feline class I major histocompatibility complex gene), from three different individual fossil specimens were cloned and sequenced after PCR amplification. Comparison of fossil-derived DNA sequences to homologous regions in 15 living carnivorous species, including 9 species of Felidae and 6 nonfelids, affirmed the phylogenetic placement of Smilodon within the modern radiation of Felidae distinct from the Miocene paleofelid (Nimravidae) saber-toothed "cat" species. These results raise the prospect of obtaining genetically informative DNA from preserved bones of extinct fossil species, particularly among the 2 million specimens excavated from the asphaltic sediments at Rancho La Brea in metropolitan Los Angeles.     

The multidomain protein Trio binds the LAR transmembrane tyrosine phosphatase, contains a protein kinase domain, and has separate rac-specific and rho-specific guanine nucleotide exchange factor domains.

rho-like GTP binding proteins play an essential role in regulating cell growth and actin polymerization. These molecular switches are positively regulated by guanine nucleotide exchange factors (GEFs) that promote the exchange of GDP for GTP. Using the interaction-trap assay to identify candidate proteins that bind the cytoplasmic region of the LAR transmembrane protein tyrosine phosphatase (PT-Pase), we isolated a cDNA encoding a 2861-amino acid protein termed Trio that contains three enzyme domains: two functional GEF domains and a protein serine/threonine kinase (PSK) domain. One of the Trio GEF domains (Trio GEF-D1) has rac-specific GEF activity, while the other Trio GEF domain (Trio GEF-D2) has rho-specific activity. The C-terminal PSK domain is adjacent to an Ig-like domain and is most similar to calcium/calmodulin-dependent kinases, such as smooth muscle myosin light chain kinase which similarly contains associated Ig-like domains. Near the N terminus, Trio has four spectrin-like repeats that may play a role in intracellular targeting. Northern blot analysis indicates that Trio has a broad tissue distribution. Trio appears to be phosphorylated only on serine residues, suggesting that Trio is not a LAR substrate, but rather that it forms a complex with LAR. As the LAR PTPase localizes to the ends of focal adhesions, we propose that LAR and the Trio GEF/PSK may orchestrate cell-matrix and cytoskeletal rearrangements necessary for cell migration.     

Comparative Functional Effects of Chronic Ventricular Demand and Atrial Synchronous Ventricular Inhibited Pacing

We compared the effects of chronic ventricular inhibited (VVI) and atrial synchronous ventricular inhibited (VDD) pacing on functional capacity in 8 patients with complete atrioventricular heart block. Permanent VDD (Medtronic #2409, ASVIP) pacemakers were implanted in four men and four women (age range 27-76 years, mean 58.9 +/- 18.4 years), and randomly assigned to a three-month period of VDD or VVI pacing in this single blinded, crossover study. Functional capacity was assessed by questionnaire, graded treadmill exercise testing and radionuclide angiocardiography prior to pacemaker implant and following each pacing period. Following 3 months of pacing in each of VVI and VDD pacing modes, maximum heart rate (83.4 +/- 14 vs 134.9 +/- 16.4 beats/min, p less than 0.001) and double product (147.5 +/- 58.3 vs 218.9 +/- 52.7, p less than .001) were greater with VDD pacing. Although exercise duration on treadmill exercise testing (5.3 +/- 2.9 vs 6.9 +/- 3.1 minutes, p less than 0.1) was greater in the VDD mode, the difference was not significant. Similarly, there was no significant difference in functional capacity as measured by questionnaire scores (50.1 +/- 8.4 vs 46.9 +/- 8.9, p less than 0.1) or in left ventricular ejection fraction for the two pacing modes (.54 vs .55, p less than .5). Only one patient reported a subjective improvement with physiologic (VDD) pacing, whereas the remaining patients stated no preference. We conclude that VDD pacing offers improved maximal cardiac work during exercise compared to VVI pacing.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of saliva contamination and phosphoric acid composition on bond strength

The purpose of this study was to determine the effects of a phosphoric acid gel and solution, and saliva contamination of etched enamel on the tensile bond strength (TBS) of a posterior composite resin to etched enamel. Ninety-six extracted human permanent maxillary canines were used in this study. The test system developed by Kemper and Kilian was used to determine the TBS of a posterior composite resin (P-10) to enamel. The ground enamel surfaces were etched with 37% H₃PO₄ gel for 60 sec and washed for 15 sec or 30 sec, and with 37% H₃PO₄ solution for 60 sec and washed for 15 sec or 30 sec, respectively. The ground enamel surfaces were also etched with H₃PO₄ gel for 60 sec, washed for 15 sec and rewashed for 15 sec after saliva contamination of the etched enamel for 15 sec, 60 sec and 60 min, respectively. Etched enamel surfaces contaminated with saliva for 15 sec were re-etched for 15 sec and washed for 15 sec. The test specimens were mounted in an Instron machine and subjected to a tensile load at 0.02 inch. min⁻¹. The force required to break a test specimen was recorded, and the bond strengths were calculated and expressed in MN.m⁻². The data were analyzed by ANOVA and Duncan's multiple range test at the 5% level of significance. The H₃PO₄ composition (gel vs solution) and wash times had no significantly different effect on TBS. Only a 60 min saliva contamination significantly reduced TBS. In this study the TBS was determined 24 h after specimen preparation. It is possible that salivary contamination of etched enamel may have an adverse effect on bond strength only after prolonged immersion of the test specimens prior to testing.     

马来酸曲美布汀治疗肠易激综合征对比研究

目的探讨马来酸曲美布汀对肠易激综合征的治疗效果。方法将诊断为肠易激综合征（IBS）的97例患者随机分成试验组（47例）和对照组（50例），试验组给予马来酸曲美布汀，对照组使用复合维生素B作为安慰剂，两组疗程均为6周，治疗期间均停用其他药物，分别于治疗前及治疗的第2、4、6周及随访8、12周末进行症状评价及评分。结果试验组治疗后积分明显下降，治疗前后比较差异有非常显著性（P〈0．01）；对照组积分下降不明显，治疗前后比较差异无显著性（P〉0．05）；治疗4周后两组间比较，试验组积分下降较对照组明显，差异有非常显著性（P〈0．01）；治疗后两组疗效比较，试验组在2周后有效率达34％，8周和12周时分别达到83％和82％，疗效明显高于对照组，差异有非常显著性（P〈0．01）。结论马来酸曲美布汀对难治性功能性消化不良具有良好的治疗作用和安全性。