Molecular cloning of an amphibian insulin receptor substrate 1-like cDNA and involvement of phosphatidylinositol 3-kinase in insulin-induced Xenopus oocyte maturation

An insulin receptor substrate 1 (IRS-1)-like cDNA was isolated from a Xenopus ovary cDNA library by low-stringency hybridization using rat IRS-1 cDNA as a probe. The deduced amino acid sequence encoded by this cDNA (termed XIRS-L) is 67% identical (77% similar) to that of rat IRS-1. Significantly, all the insulin-induced tyrosine phosphorylation sites identified in rat IRS-1, including those responsible for binding to the Src homology domains of phosphatidylinositol (PI) 3-kinase, Syp and Grb2, are conserved in XIRS-L. Both mRNA and protein corresponding to the cloned XIRS-L can be detected in immature Xenopus oocytes. Recombinant XIRS-L protein produced in insect cells or a bacterial glutathione S-transferase fusion protein containing the putative PI 3-kinase binding site can be phosphorylated in vitro by purified insulin receptor kinase (IRK) domain, and the IRK-catalyzed phosphorylation renders both proteins capable of binding PI 3-kinase in Xenopus oocyte lysates. Another glutathione S-transferase fusion protein containing the C terminus of XIRS-L and including several putative tyrosine phosphorylation sites is also phosphorylated by IRK in vitro, but it failed to bind PI 3-kinase. Insulin stimulation of immature Xenopus oocytes activates PI 3-kinase in vivo [as indicated by an elevation of PI(3,4)P2 and PI(3,4,5)P3] as well as oocyte maturation (as indicated by germinal vesicle breakdown). Pretreatment of these oocytes with wortmannin inhibited insulin-induced activation of PI 3-kinase in vivo. The same treatment also abolished insulin-induced, but not progesterone-induced, germinal vesicle breakdown. These results (i) identify an IRS-1-like molecule in immature Xenopus oocytes, suggesting that the use of IRS-1-like Scr homology 2 domain-docking proteins in signal transduction is conserved in vertebrates, and (ii) strongly implicate PI 3-kinase as an essential effector of insulin-induced oocyte maturation.

Ovariectomy and age alter gonadotropin hormone releasing hormone-noradrenergic interactions

The noradrenergic (NA) system influences gonadotropin hormone releasing hormone (GnRH) neurons resulting in the luteinizing hormone surge. Direct neuroanatomical interactions between preoptic area (POA) GnRH neuronal elements and NA [i.e., dopamine-beta-hydroxylase (DBH)] terminals; effects of short-term ovariectomy (S-OVX) on these interactions; and the stability of these interactions with age were studied in young (5-month-old) proestrous, 5-month-old S-OVX (6d), old (24-month-old) constant diestrous, and 24-month-old long-term (L)-OVX mice. Proestrous females demonstrated direct interactions between NA terminals and GnRH neuronal elements. The percentage of GnRH dendritic profiles contacted by DBH terminals at proestrous (6.96 +/- 1.07%) did not differ versus young S-OVX females (4.55 +/- 0.91%). No GnRH-NA interactions were observed in old mice. S-OVX resulted in a decrease in DBH terminals but an increase in dendrite and nonmyelinated axon number versus young proestrous females (p < or = 0.05 ANOVA). Findings show direct GnRH-DBH interactions, confirm S-OVX effects on neural ultrastructure, and demonstrate some S-OVX changes resembling those in older mice. L-OVX failed to prevent aging changes. Diminished capacity to produce normal estrous cycles in aging females could result in part from absence of direct GnRH-DBH interactions.

Developmental regulation of troponin I isoform genes in striated muscles of transgenic mice

The differentiation and diversification of striated muscle is a complex process involving numerous temporal and spatial alterations in the pattern of contractile protein isoform gene expression. In order to gain insight into the regulation of contractile protein isoform changes during skeletal and cardiac muscle formation, the expression of a transgene comprising a chloramphenicol acetyltransferase (CAT) reporter gene linked with sequences from -4200 to +12 of the human slow skeletal troponin I (TnIs) gene, and all three endogenous mouse troponin I (TnI) isoform genes, was investigated in embryonic, neonatal, and postnatal mice. The -4200 TnIsCAT transgene was properly activated in the limb and trunk skeletal muscle primordia and the early embryonic atrium and ventricle of the heart. Along with the endogenous mouse TnIs gene, expression of the CAT transgene began to segregate into the presumptive slow-twitch myofibers at late fetal stages and expression declined in the neonatal and postnatal heart except for the conductive tissues, in which expression persisted into adulthood. However, expression of the CAT transgene during development did not completely follow the endogenous mouse TnIs gene. The expression of the CAT transgene was aberrantly low in the embryonic cardiac outflow tract and the ventricles of the fetal heart. In addition to its expression in striated muscles, the transgene was expressed aberrantly in the primordial axial skeleton. We conclude that the upstream sequences from the human TnIs gene contain sufficient regulatory information to confer appropriate transgene expression during the early differentiation of skeletal muscles and during the establishment of fiber type upon the maturation of myofibers. However, additional regulatory elements are likely to be required for correct temporal and spatial regulation in the heart and somitic mesoderm during development. In vitro DNA transfection of cultured skeletal and cardiac muscle cells identified a cell type-specific enhancer element within the first intron of the TnIs gene whose absence in the transgene may account for the aberrant expression observed in vivo. In addition, we provide the first evidence that the fast-twitch skeletal muscle isoform of troponin I, TnIf, is transiently expressed during early cardiac muscle development.

[Clinical management of bidirectional cavopulmonary anastomosis]

The procedure of bidirectional cavopulmonary anastomosis (DBCPA) is an effective method for the treatment of some complex congenital heart diseases. The clinical results of the procedure as a part of total cavopulmonary anastomosis were better than those of fontan operation in the treatment of single ventricle and tricuspid atresia. 6 cases were treated by using this procedure in our department in recent years. All of them receives total pulmonary anastomosis, but one this procedure plus ASD closure for the treatment of Ebstein anomaly with tricuspid valve stenosis and right heart hypoplasia. There were 5 cases survived in the early stage and one case died of acute pump failure. And one case died of sepsis two months after operation.

[Study on determination of gentamycin in serum by enhanced chemiluminesent immunoassay based on immobilized antibody and biotin-avidin system]

Gentamycin was determined by competition with biotin labeled gentamycin in the presence of an immobilized antibody to gentamycin. Microcrystalline cellulose was first coupled with sheep anti-rabbit antibody, then the anti-gentamycin antibody was conjugated and the competition reaction conducted. After separation, HRP-avidin was added to the precipitation and the amount of HRP conjugate determined by enhanced chemiluminescene. The limit of detection for gentamycin in serum was 63-78 ng/tube and the average recovery of gentamycin 103%. The correlation coefficient of the log-log regression equation. Magnitude of r was 0.991 +/- 0.006.

A Drosophila gene that encodes a member of the protein disulfide isomerase/phospholipase C-alpha family

Screening of a Drosophila genomic DNA library at reduced stringency hybridization conditions using a rat PLC alpha cDNA probe yielded a gene which encodes a member of the protein disulfide isomerase/PLC alpha family. The gene has been localized to band 74C on the left arm of the third chromosome and has been designated dpdi. Northern analysis shows that the dpdi gene encodes a transcript that is 2.3 kb in length and is present throughout development as well as in both heads and bodies of adults. The deduced dpdi protein is 496 amino acids in length and contains two domains exhibiting high similarity to thioredoxin, two regions that are similar to the hormone binding domain of human estrogen receptor, and a sequence of four amino acids (KDEL) at the C-terminus which has been described by others as being responsible for retention of proteins in the endoplasmic reticulum. Overall, dpdi contains a higher similarity to rat protein disulfide isomerase (53% identical) than to rat PLC alpha (30% identical). However, it is unclear whether dpdi functions in vivo as a PDI or as a PLC, or both. Drosophila, with its well characterized genetics and the ability to generate mutants in a gene that has been cloned, provides an excellent system in which to resolve this issue.

The pRB-related protein p107 contains two growth suppression domains: independent interactions with E2F and cyclin/cdk complexes

Unregulated expression of either the retinoblastoma protein (pRB) or the related protein p107 can cause growth arrest of sensitive cells in the G1 phase of the cell cycle. However, growth arrests mediated by p107 and pRB are not identical. Through structure-function and co-expression analyses we have dissected the p107 molecule into two domains that independently are able to block cell cycle progression. One domain corresponds to the sequences needed for interaction with the transcription factor E2F, and the other corresponds to the interaction domain for cyclin A or cyclin E complexes. In cervical carcinoma cell line C33A, which was previously shown to be sensitive to p107 but resistant to pRB growth suppression, only the cyclin binding domain is active as a growth suppressor. Furthermore, we show that these two independent domains are functional in untransformed mouse fibroblasts. Together, these results provide experimental evidence for the presence of two functional domains in p107 and pinpoint an important functional difference between p107 and pRB.

Anomalous origin of left coronary artery from pulmonary artery. Successful correction for a 7-year-old patient

A 7-year-old girl with an anomalous origin of the left coronary artery from the pulmonary artery restored connection of the left coronary artery to the ascending aorta by aortocoronary bypass graft. Aortocoronary bypass grafting was performed with a vascular prosthesis. Postoperative angiography showed a patent left coronary artery without narrowing or kinking. Clinical improvement was rapid and the left ventricular function recovered completely.

Expression of heat-stable antigen on tumor cells provides co-stimulation for tumor-specific T cell proliferation and cytotoxicity in mice

Heat-stable antigen (HSA/J11d/possibly homologous to CD24), a cell adhesion molecule capable of providing a co-stimulatory signal for T cell proliferation, is expressed on B cells, activated T cells, monocytes, granulocytes, Langerhans cells and thymocytes. Recent studies have demonstrated that co-stimulatory signals provided by cell adhesion molecules such as B7-1 play an essential role in generation of an anti-tumor immune response. To examine whether the co-stimulatory signal provided by HSA can induce an anti-tumor immune response, we have transfected HSA cDNA into the murine melanoma cell line K1735M2, and examined the ability of this transfected cell line to induce tumor-specific T cell responses. The results demonstrate that spleen cells from mice immunized with HSA-transfected K1735M2 cells showed enhanced T cell proliferation in a mixed lymphocyte tumor reaction (MLTR) assay and also demonstrated a significant anti-tumor cytotoxicity to the parent tumor cell (K1735M2). This anti-tumor cytolytic activity could be abrogated by pretreatment of effector cells with anti-mouse CD8 monoclonal antibody and complement. Under similar conditions, spleen cells from C3H mice immunized with vector-transfected K1735M2 cells neither actively proliferate in an MLTR assay, nor did they exert significant cytolytic activity against the respective tumor cells. In summary, our study demonstrated that HSA can provide a co-stimulatory signal for the T cell immune response against tumor cells in a murine model.

[Diagnosis and misdiagnosis of fracture of the femoral head]

164 cases of traumatic posterior dislocation of the hip, of which 26 were associated with fractures of the femoral head, about 15.9% incidence, were treated during the year from March 1982 to March 1993. According to the pipkin classification of fractures of the femoral head, 10 cases were type 1, 6 tupe 2, 2 type 3, and 8 type 4. Of the 26 cases, 24 received emergent radiography, with 22 diagnosed and 2 misdiagnosed. The other 2 cases were found prompt auto-reduction of dislocation of the femoral head, without emergent radiography. The 4 misdiagnosed cases, because of continued pain or redislocation, came back later for radiography and then were correctly diagnosed. Besides the routine anteroposterior radiograph of the hip, pelvic oblique radiography angled 45 degrees or 60 degrees, and frog-leg anteroposterior hip radiography were needed. The CT-directed pelvic oblique radiograph was found to be the most accurate determinant of the extent of fracture displacement and the presence of intrasarticular loose fragments. Among the 19 cases operated on, 16 showed excellent-good rate (50%), and among the 7 non-operated cases, of 6 showed excellent-good rate (33%). After follow up.

Localized distribution of alpha 9 integrin in the cornea and changes in expression during corneal epithelial cell differentiation

A recently characterized integrin alpha-chain, alpha 9, forms heterodimers with the integrin beta 1-chain and is present in the skin with a distribution similar to that of alpha 2 and alpha 3, other beta 1 integrins. To determine whether alpha 9 is expressed in the stratified squamous epithelium of the cornea, we used immunohistochemical techniques to compare the distribution of alpha 9 in the adult mouse cornea with that of alpha 3. Abundant alpha 9 was expressed in the lateral and basal membranes of the basal cells of the conjunctiva and corneal limbus, but very little alpha 9 was present in the basal cells of the central corneal epithelium. In contrast, alpha 3 was present in the membranes of basal cells of the conjunctiva, limbus, and central cornea. To determine when during postnatal maturation of the corneal epithelium alpha 9 becomes restricted to the limbus, we looked at the distribution of alpha 9 and alpha 3 in the developing mouse eye from birth to eyelid opening. At birth, the basal cells of the cornea and developing limbal region did not express alpha 9, but there was abundant alpha 9 expressed in suprabasal cells between the fused lids and in the basal cells of the skin and conjunctiva. In contrast, alpha 3, integrin was expressed uniformly in the basal cells across the surface of the conjunctiva, limbus, and cornea and was present only in the basal cells of the epithelium between the fused eyelids. In the central cornea, alpha 9 expression increased in basal cells up until Day 10 after birth. After Day 10, alpha 9 expression in the central cornea began to decrease; after the lids were open, alpha 9 expression in the central cornea became restricted to the limbus. In the basal and suprabasal cells between the fused eyelids expression of alpha 9 became increasingly restricted over time to the basal cells. Recent data suggest that alpha 9 beta 1 can interact with tenascin. Our dual labeling confocal microscopy studies indicate that localization of alpha 9 and tenascin are not coordinated in the developing mouse cornea. Many recent studies have shown an important role for beta 1 integrins in mediating epithelial cell differentiation in vitro; in vivo, changes in integrin expression have been found in wound healing, psoriasis, and in basal and squamous cell carcinomas.(ABSTRACT TRUNCATED AT 400 WORDS)

An improved NOESY simulation program for partially relaxed spectra: BIRDER

An improved 2D NOESY simulation program, BIRDER (back-calculation considering incomplete recovery and differential external relaxation), has been developed. BIRDER has the following features: (1) It allows for differential external relaxation rates for protons with different chemical environments, (2) it automatically accounts for incomplete recovery of z magnetization between scans, and (3) it incorporates anisotropic tumbling motional modes for nonspherical molecules. It was found that a lower R factor is obtained if differential external relaxation rates are used in the NOESY spectrum simulation. The method for experimentally determining these external relaxation rates is discussed. In practice, the ability to account for incomplete recovery of z magnetization is very useful in the quantitative analysis of 2D NOESY spectra of spin systems with long longitudinal relaxation times (T1). For example, the T1's of some protons in RNA duplexes are approximately 4-6 s. Thus, a more than 15 s relaxation delay is needed to allow the z magnetization to return to thermal equilibrium between scans, requiring more than a week to obtain a single NOESY spectrum. Unless incomplete recovery of z magnetization is explicitly considered, distance errors may arise when shorter relaxation delays are used. The situation is further complicated in studies of DNA:RNA hybrid or DNA-RNA chimeric duplexes in which the DNA protons relax much faster than the RNA protons. It is shown that BIRDER successfully corrects for the incomplete recovery of z magnetization and makes it possible to save spectrometer time by using shorter relaxation delays without introducing serious errors. The nonsymmetrical nature of NOESY spectra when the spin system is not fully relaxed is discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

[A study on the relative factors for secondary parathyroidosis and renal osteodystrophy in long-term hemodialysis patients]

The authors classified sixty chronic renal failure (CRF) patients receiving hemodialysis (HD) treatment into four groups for clinical study. Forty patients received HD for more than five years and the remaining twenty patients received HD for less than two years. These two groups were further divided into two subgroups according to whether they took Rocaltrol or not. The levels of parathyroid hormone (PTH), calcitonin (CT), alkaline phosphatase (AKP) and bone X-ray were studied in each patient. The results showed: the levels of PTH and CT were obviously increased in all the patients. The levels of PTH and CT were higher in the patients having received HD for more than five years than those for less than two years. They were also higher in patients who had not taken Rocatrol than those who had. Ninety-five percent of the patients having received HD for more than five years had renal osteodystrophy (ROD) without receiving Rocaltrol treatment, while only sixty-five percent of the patients developed ROD with Rocatrol treatment. The longer the HD time, the higher the ROD incidence. The cause, prevention and treatment of ROD were discussed.

Morphometric evaluation on myocardial protection of cold crystalloid versus warm blood cardioplegia

Twenty patients undergoing open-heart valve replacement were divided randomly into two groups in this study; intermittent perfusion of cold crystalloid (St. Thomas Hospital solution) with hypothermic cardiopulmonary bypass (CPB) (hypothermic group) and continuous administration of warm blood cardioplegia with normothermic CPB (normothermic group) respectively. Tissue samples were taken from the right atrium before weaning from CPB and from the right appendage 30 minutes after removal of the cross-clamp. The results of pathological study in these two groups were as follows: the structural alterations were most severe during the ischemic period in the hypothermic group. Damages of the myocardial mitochondria examined with transmission electron microscope were found more severe in the hypothermic group than in the normothermic group, and in the reperfusion period than in the ischemic period. Loss of integrity of the mitochondrial membrane could be noted during reperfusion in the hypothermic group. The surface to volume ratios of mitochondria of each period of the two groups were calculated by computerizing the microphotographs of the myocardium. It was shown that the average of the surface to volume ratios was smallest in the reperfusion period in the normothermic group. It seemed that the volumes of the mitochondria were larger in the warm group than in the cold one. Probably the results were due to more severe damages of the mitochondrial membranes in the hypothermic group, which led to the release of the contents out of the mitochondria while in the normothermic group, the sodium-pump was disordered and it made the mitochondria swell. Pathologically, blood cardioplegic perfusion with the use of normothermic CPB is a feasible method for myocardial protection in open-heart surgery.

DNA duplexes flanked by hybrid duplexes: the solution structure of chimeric junctions in [r(cgcg)d(TATACGCG)]2

Hybrid duplexes and chimeric duplexes containing hybrid segments linked to pure DNA (or pure RNA) segments are involved in transcription and replication, as well as reverse transcription. A complete understanding of the mechanism of these processes requires detailed information on such duplexes and the junctions between duplexes of differing structure. Using two-dimensional NMR, restrained molecular dynamics and mechanics, and back-calculation refinement against the nuclear Overhauser effect spectra at various mixing times, we have determined the solution structure of the chimeric duplex [r(cgcg)d-(TATACGCG)]2 containing a pure DNA segment in the center of a hybrid duplex. The solution structure differs from the previously determined X-ray structure of the analogous duplex [r(gcg)d(TATACGC)]2, which was found to be A-form throughout [Wang, A.H.-J., et al. (1982) Nature 299, 601-604]. The basic features of the solution structure are (a) the RNA residues are all A-form with C3'-endo sugar conformations, (b) the central DNA segment is B-form, (c) the transition from A-form RNA sugar conformations to B-form DNA sugar conformations involves only the dT5 base step, and (d) although the sugar conformations of the DNA residues A6-G12 are closer to B-form, the basic helical properties of the peripheral RNA.DNA hybrid segments are closer to typical A-form than to B-form.

A model for heat transfer from embedded blood vessels in two-dimensional tissue preparations

Two-dimensional microvascular tissue preparations have been extensively used to study blood flow in the microcirculation, and, most recently, the mechanism of thermal equilibration between thermally significant countercurrent artery-vein pairs. In this paper, an approximate three-dimensional solution for the heat transfer from a periodic array of blood vessels in a tissue preparation of uniform thickness with surface convection is constructed using a newly derived fundamental solution for a Green's function for this flow geometry. This approximate solution is exact when the ratio K' of the blood to tissue conductivity is unity and a highly accurate approximation when K' not equal to 1. This basic solution is applied to develop a model for the heat transfer from a countercurrent artery-vein pair in an exteriorized rat cremaster muscle preparation. The numerical results provide important new insight into the design of microvascular experiments in which the axial variation of the thermal equilibration in microvessels can be measured for the first time. The solutions also provide new insight into the design of fluted fins and microchips that are convectively cooled by internal pores.

[Flow cytometry used to distinguish between complete and partial hydatidiform moles]

The nuclear ploidy of 14 placentas was determined by flow cytometry. All histologically classified complete moles (4 cases), hydropic villi (4 cases) and control placentas (3 cases) were diploid; whereas two of three histologically classified partial moles were triploid. The remaining case classified as partial mole was diploid, most likely a complete mole. It was concluded that DNA flow cytometric analysis offers an informative supplement to the histological interpretation of hydropic placentas.

E2F-independent transcriptional repression by p107, a member of the retinoblastoma family of proteins

The Rb family of proteins includes pRb, p107, and p130. These nuclear polypeptides associate with cyclins and transcription factors involved in the control of cell proliferation. This has suggested that members of the pRb family may modulate cell growth, at least in part, by regulating gene transcription. We have investigated the ability of p107 to modulate transcription and compared it with that of pRb. Whereas pRb inhibition of the c-myc promoter required the presence of E2F sites, p107 inhibition did not. Moreover, p107, but not pRb, repressed transcription from other promoters including fibronectin, herpes virus thymidine kinase, and a synthetic promoter containing a SV40 repeat activator motif upstream from the adenovirus major late-promoter TATA box. In contrast, the activity of the TATA-lacking promoters from the epidermal growth factor receptor and the cytoplasmic phospholipase A2 genes was unaffected by either p107 or pRb. Likewise, overexpression of p107 or pRb had no effect on the activity of a synthetic promoter lacking a TATA box and containing the SV40 repeat motif upstream from the terminal transferase gene initiator element. The domains in p107 required for transcriptional repression included the A segment of the pocket region and parts of the B segment, but not the spacer domain. In spite of their structural similarities, p107 and pRb may contribute to the control of cell proliferation by modulating the transcription of different genes.

Donor-specific cytotoxicity induced by allogeneic intestinal epithelial cells in a sponge matrix model

Small intestinal epithelial cells (IEC) constitutively express MHC class II molecules. However, little is known about the role of IEC in intestinal allograft rejection. The present study examined whether IEC can induce the development of cytotoxic T cells in vivo using a sponge matrix model. IEC isolated from ACI (RT1a) rats were injected into polyurethane sponges implanted i.p. in Lewis (RT1(1)) rats. Sponge grafts with ACI splenocytes or Lewis IEC were used as controls. The sponge grafts were removed and sponge-infiltrating cells (SIC) were harvested on post-operative days (POD) 7, 10, and 14. The phenotype of SIC was determined by FACS analysis and the cell-mediated cytotoxicity was measured using a chromium relapse assay. Non-specific inflammatory cells accumulated in the IEC sponge allografts during the first 10 days. By POD 14, however, 61% of SIC were T lymphocytes and 36% expressed cytotoxic T cell marker (OX-8). The cytotoxicity in IEC sponge allografts was detectable on POD 7 and POD 10, and markedly elevated on POD 14. The cytotoxicity induced by allogeneic splenocytes appeared in the sponge grafts on POD 7, peaked on POD 10, and declined thereafter. The allospecific cytotoxicity induced by IEC was dependent on host macrophages as pretreatment of animals with gadolinium, a rare earth metal that inactivates macrophages, abrogated the induction of cytotoxicity. We conclude that: (1) the migration and maturation of cytotoxic T cells can be induced in vivo by IEC and (2) IEC may contribute to the increased severity of intestinal rejection through interaction with macrophages.

[Effects of dopexamine on the electrophysiologic changes during myocardial ischemia and comparison with fenoldopam and procaterol]

The effects of dopexamine (DPX), a new dopamine receptor agonist, on transmembrane potential and effective refractory period (ERP) of isolated guinea pig ventricular muscle superfused either with hypoxia or mimic ischemia perfusates were investigated by using intracellular microelectrode technique and compared with fenoldopam (FODA) and procaterol. DPX (3 x 10(-6) mol.L-1) was found to significantly reduce both the extent of decrease of resting potential, action potential amplitude and maximal upstroke velocity and the degree of shortening of action potential duration caused by hypoxia or ischemia. These effects of DPX were significantly greater than those of FODA and procaterol albeit the latter showed effects similar to DPX. DPX could not only lengthen the abbreviated ERP resulting from hypoxia, but also shorten the prolonged ERP caused by ischemia. This action of DPX was more evident than that of FODA and procaterol. The results reveal the potential advantages of DPX over other dopaminergic agonists in the antiarrhythmic activity during myocardial ischemia.