[Experience in repair of eyelid ectropion with temporofrontal flap]

We used the temporofrontal flap to repair eyelid ectropion in 12 patients. The results were satisfactory. The indications, advantages and disadvantages, and the points for attention of this operation method were discussed. Experiences and lessons were summarized in this article.

[Evaluation of two glycolipids from M. tuberculosis in the serodiagnosis of tuberculosis]

Sera from 112 healthy controls and 120 pulmonary tuberculous patients (61 untreated patients and 59 active patients) were assayed, by ELISA, to test the activity of IgG and IgM antibodies against antigen of 2, 3-diacyl-trehalose-2'-sulphate (SL IV) a phenolglycolipid antigen (PGLTb1) and purified protein derivative (PPD) from M. tuberculosis. Respectively, for SL IV-IgG-ELISA, SL IV-IgM-ELISA, PGLTb1-IgG-ELISA, PGLTb1-IgM-ELISA, PPD-IgG-ELISA, the specificities were of 96.43, 96.43, 96.43, 96.43 and 95.53%; the sensitivities were of 51.67, 32.50, 14.17, 18.33 and 33.33%; the efficiencies were of 73.28, 63.36, 53.88, 56.03 and 62.93%; the predictive values for a positive result were of 96.87, 86.67, 80.95, 84.62 and 88.64%. Among the three antigens tested, SL IV was found to be better than PGLTb1 and PPD.

Genetic analysis of a phosphatidylinositol 3-kinase SH2 domain reveals determinants of specificity

Phosphatidylinositol 3-kinase is an important element in both normal and oncogenic signal transduction. Polyomavirus middle T antigen transforms cells in a manner depending on association of its tyrosine 315 phosphorylation site with Src homology 2 (SH2) domains on the p85 subunit of the phosphatidylinositol 3-kinase. Both nonselective and site-directed mutagenesis have been used to probe the interaction of middle T with the N-terminal SH2 domain of p85. Most of the 24 mutants obtained showed reduced middle T binding. However, mutations that showed increased binding were also found. Comparison of middle T binding to that of the platelet-derived growth factor receptor showed that some mutations altered the specificity of recognition by the SH2 domain. Mutations altering S-393, D-394, and P-395 were shown to affect the ability of the SH2 domain to select peptides from a degenerate phosphopeptide library. These results focus attention on the role of the EF loop in the SH2 domain in determining binding selectivity at the third position after the phosphotyrosine.

DNA sequencing with a hexamer string primer and dye-labeled terminators

A method for fluorescence-based DNA sequencing using a hexamer string primer and dye-labeled terminators is described. Sequencing protocols have been determined that provide an average read length of 393 bases with 99.6% base-calling accuracy for single-stranded M13mp18 DNA, and an average read length of 367 bases with 99.4% base-calling accuracy for double-stranded M13mp19 DNA. The signal intensity is stronger than that obtained with a standard 18-mer primer, while the resolution and length of readable sequence are comparable.

Identification of two SH3-binding motifs in the regulatory subunit of phosphatidylinositol 3-kinase

Src homology 3 (SH3) domains have been recently shown to bind to proline-rich sequences contained in 3BP1, 3BP2, and SOS. In a recent study we demonstrated that phosphatidylinositol 3-kinase (PI 3-kinase) associates with the Fyn SH3 domain. Here we show that p85, the regulatory subunit of PI 3-kinase, binds directly to the SH3 domains of Abl, Lck, Fyn, and p85 itself. An examination of p85 amino acid sequence revealed two proline-rich sequences in its N-terminal region similar to those present in 3BP1, 3BP2, and SOS. To test whether these sequences mediate the association of p85 with SH3 domains two peptides with amino acid composition corresponding to the p85 alpha proline-rich sequences were synthesized and used in competition assays. Both peptides worked equally well in inhibiting the binding of PI 3-kinase activity and p85 alpha to Fyn SH3 domain, whereas a control peptide had no effect. These results indicate that, as in 3BP1 and SOS, the proline-rich sequences in p85 mediate its interaction with SH3 domains. These results also suggest that the SH3 domain of p85 may "self-associate" with the proline-rich motifs of the same subunit as part of the PI 3-kinase regulatory mechanism.

Poly(A) site selection in the yeast Ty retroelement requires an upstream region and sequence-specific titratable factor(s) in vitro

In the Ty retrotransposon of Saccharomyces cerevisiae, as in most retroelements, the polyadenylation site of the 5' long terminal repeat (LTR) is ignored and the one in the 3' LTR is efficiently used. We examine here the contribution to this poly(A) site selection of the region termed 'U3', corresponding to the upstream non-transcribed portion of the 5' LTR. Using an established assay in vitro, we find that 3' processing is accurate and efficient with an RNA substrate corresponding to most of the LTR, whereas none is detectable with a shorter transcript lacking the U3 region, thus explaining why the 5' poly(A) site is ignored in genomic Ty mRNA. When HIS4 coding RNA, representing 'non-specific' sequence, replaces the U3 region, the Ty polyadenylation site is activated to 50% of the wild-type level. Within one specific region (TS1) in U3, 90-95 nt upstream of the poly(A) site, the change of UAGUAU to UCGCAU reduces processing efficiency by half, to the non-specific level provided by other sequences or by a deletion of the TS1 region. Another region (TS2) near the poly(A) site appears to be independently responsible for the remaining half of the processing activity. Alteration of both TS1 and TS2 eliminates processing entirely. In competition assays, excess unlabeled U3, but not its mutated counterparts, reduces the processing of radiolabeled Ty mRNA, suggesting the involvement of some sequence-specific titratable factor(s) in the whole cell extract for U3-specific activation.(ABSTRACT TRUNCATED AT 250 WORDS)

[Detection of antibodies to sulpholipid IV from mycobacterium tuberculosis in pulmonary tuberculosis patients]

Serum IgG and IgM antibodies against a novel 2,3-diacyl-trehalose-2'-sulphate (SLIV) antigen using ELISA were determined in control (n = 112) and in pulmonary tuberculosis (n = 120) patients. The specificity and sensitivity of SLIV-IgG-ELISA were 96% and 52%, respectively. Those of SLIV-IgM-ELISA were 95% and 33%, respectively. Compared with PPD-IgG-ELISA, SLIV-IgG-ELISA showed that the specificity was about the same but the sensitivity was higher.

Solitary pedunculated polypoid gastric gland heterotopia

A solitary pedunculated gastric polyp in the gastric fundus was removed from an asymptomatic 36-year-old woman with normal gastric acid secretion and a normal serum gastrin level. This lesion exhibited distinctive histological features including prominent proliferation of pseudopyloric glands, fundic glands, foveolar epithelium and a fibromuscular stroma. Moreover, its surface was entirely covered by a layer of normal gastric epithelium. Biopsies of the background mucosa taken from the gastric fundus revealed only mild superficial gastritis. A gastric gland heterotopia was diagnosed because of its unique morphology.

Secretion of somatostatin and gastrin by human antral mucosa--an in vitro study in duodenal ulcer patients and control subjects under stimulation of bombesin

In order to ascertain possible abnormalities in somatostatin and gastrin secretion in patients with duodenal ulcer, the author compared bombesin-stimulated somatostatin and gastrin secretion by antral mucosal explants in patients with duodenal ulcer, those with atrophic gastritis and normal controls. An organ culture technique was employed. This excluded neurogenic, hormonal and circulatory influences. Bombesin in concentrations of 10(-7) M to 10(-5) M stimulated gastrin and somatostatin secretion at a dose-dependent manner. In all subjects, bombesin (10(-7) M) stimulated antral gastrin release and increased explant gastrin content significantly (p < 0.05). Bombesin significantly increased somatostatin release and explant somatostatin content in normal subjects (p < 0.05) but not in patients with duodenal ulcer (p > 0.05). In the presence of bombesin, the total net increase of gastrin in medium and explants was greater in duodenal ulcer patients (31.57 +/- 5.20 ng/mg wet w.) compared with normal subjects (19.63 +/- 4.50 ng/mg wet w.) (p < 0.01). The total net increase of somatostatin in the presence of bombesin was significantly less in duodenal ulcer patients (0.10 +/- 0.02 ng/mg wet w.) than in normal subjects (1.45 +/- 0.24 ng/mg wet w.) (p < 0.01). The results suggest that abnormalities in somatostatin and gastrin secretion of the antrum contribute to the pathogenesis of increased gastric acid secretion in duodenal ulcer.

Interactions of polyomavirus middle T with the SH2 domains of the pp85 subunit of phosphatidylinositol-3-kinase

The binding of phosphatidylinositol-3-kinase to the polyomavirus middle T antigen is facilitated by tyrosine phosphorylation of middle T on residue 315. The pp85 subunit of phosphatidylinositol-3-kinase contains two SH2 domains, one in the middle of the molecule and one at the C terminus. When assayed by blotting with phosphorylated middle T, the more N-terminal SH2 domain is responsible for binding to middle T. When assayed in solution with glutathione S transferase fusions, both SH2s are capable of binding phosphorylated middle T. While both SH2 fusions can compete with intact pp85 for binding to middle T, the C-terminal SH2 is the more efficient of the two. Interaction between pp85 or its SH2 domains and middle T can be blocked by a synthetic peptide comprising the tyrosine phosphorylation sequence around middle T residue 315. Despite the fact that middle T can interact with both SH2s, these domains are not equivalent. Only the C-terminal SH2-middle T interaction was blocked by anti-SH2 antibody; the two SH2 fusions also interact with different cellular proteins.

The bingo model of survivorship: 1. probabilistic aspects

A "bingo" model is one in which the pattern of survival of a system is determined by whichever of several components, each with its own particular distribution for survival, fails first. The model is motivated by the study of lifespan in animals. A number of properties of such systems are discussed in general. They include the use of a special criterion of skewness that probably corresponds more closely than traditional measures to what the eye observes in casually inspecting data. This criterion is the ratio, r(h), of the probability density at a point an arbitrary distance, h, above the mode to that an equal distance below the mode. If this ratio is positive for all positive arguments, the distribution is considered positively asymmetrical and conversely. Details of the bingo model are worked out for several types of base distributions: the rectangular, the triangular, the logistic, and by numerical methods, the normal, lognormal, and gamma.