Pulsed room-temperature operation of a blue-green ZnSe quantum-well diode laser

Low-threshold current density operation has been obtained from (Zn, Cd)Se/Zn(S, Se) quantum-well diode lasers in the blue-green spectrum. The devices, with reflective facet coatings, have been operated at room temperature under pulsed conditions with threshold current densities of I(th) approximately 1 kA/cm(2).

Reticuloendothelial system function following acute liver failure induced by 90% hepatectomy in the rat

Sepsis and bacterial infections are frequent complications of acute liver failure and following major liver resection. The mechanisms underlying this phenomenon are unclear. In this study, RES function and blood clearance of radiolabelled E. coli was immediately impaired following 90% hepatectomy, although the reduction in liver volume resulted in an increase in splenic (temporary) and pulmonary (persisting) uptake. A significant correlation between liver function and host RES function was observed. The uptake capacity of the RES in the liver remnant and spleen did not correlate with subserosal blood flow. The uptake in the brain gradually increased with time, paralleling an increased leakage across the blood-brain barrier. Thus, a significantly impaired RES function resulted from experimental 90% hepatectomy-induced acute liver failure, which might explain the high incidence of septic events in the clinical situation.

Follicular heterogeneity and oocyte maturation in vitro in pigs

Experiments were conducted to confirm that co-culture of follicular shells and immature pig oocytes improved the rate of male pronuclear (MPN) formation and to test the hypothesis that the maturational state of the follicle used in co-culture would significantly affect the quality of oocytes matured in vitro. In a preliminary experiment, co-culture of oocyte complexes with follicular shells did not affect nuclear maturation, slightly inhibited penetrability (p = 0.04) but greatly enhanced (p = 0.0004) MPN rate. In the main experiment, oocyte complexes (10-15 per dish), obtained from follicles 36 h after eCG injection of prepubertal gilts, were co-cultured with single 36-h small (3.5-5.0 mm), 36-h large (6-9 mm), 72-h small (4-7 mm), or 72-h large (7.5-11.0 mm) follicular shells prior to insemination. MPN formation in penetrated oocytes was significantly affected by follicular size (small: 60.14% vs. large: 72.08%, p = 0.014) but not by time of recovery (36 h: 72.32% vs. 72 h: 59.90%, p = 0.39). Overall, MPN formation rate was significantly correlated with follicular diameter (r = 0.45, p = 0.005), follicular fluid progesterone (r = 0.37, p = 0.02), and estradiol (r = 0.40, p = 0.01), and to the ratios of follicular fluid progesterone:testosterone (r = 0.39, p = 0.018) and follicular fluid estradiol:testosterone (r = 0.43, p = 0.007). There were no simple correlations between rate of MPN formation and steroid concentrations and their ratios in culture media collected at the completion of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of protein synthesis on maturation, sperm penetration, and pronuclear development in porcine oocytes

In vitro matured porcine oocytes were used to test the importance of protein synthesis for sperm penetration, the second meiotic division, and pronuclear development. Experiments were carried out to measure rates of protein synthesis in the presence of protein synthesis inhibitors (35 microM or 350 microM cycloheximide or a combination of inhibitors) (study 1); to test for sperm penetration and pronuclear development when protein synthesis was inhibited during fertilization (study 2); to test for oocyte meiosis, sperm penetration, and female and male pronuclear development when protein synthesis was inhibited during maturation (oocyte maturation in vitro with addition of inhibitor at 0, 24, or 36 hr of culture) (study 3); and to analyze the changes in the pattern of protein synthesis during these phases. Sperm penetration, oocyte meiosis, and female pronuclear development were not affected by the total inhibition of protein synthesis during fertilization. By contrast, inhibiting protein synthesis during maturation severely impaired the completion of meiosis and pronuclear development. Although inhibition of protein synthesis after 36 hr of maturation culture did not totally block male pronuclear development (MPN), the rate of MPN formation was lower than for controls (52% vs. 72%, P less than 0.05). However, protein synthesis was absolutely essential between 24 and 36 hr for the formation of MPN after decondensation. This period of maturation coincided with the dominant phase of protein reprogramming in the oocyte.

Cloning and characterization of a cDNA coding for the alpha-subunit of a stimulatory G protein from Schistosoma mansoni

Guanine nucleotide-binding proteins (G proteins) mediate signals between serotonin receptors and adenylate cyclase in Schistosoma mansoni. A bovine Gs alpha cDNA probe was used to isolate a cDNA clone, SG12, encoding the entire alpha-subunit of a G protein of S. mansoni. The cDNA is 1897 base pairs long, contains an open reading frame of 1137 base pairs, and codes for a deduced protein of 379 amino acids. The putative protein encoded by the clone has an exact amino acid match with bovine Gs alpha of 65% and a 78% match when conserved amino acid substitutions are considered. In contrast, the exact and conserved matches of the schistosome alpha-subunit with bovine Gi are 41 and 61%, respectively. A comparison of the deduced amino acid sequence of SG12 with a variety of different G alpha proteins indicates that all the major structural features characteristic of a Gs alpha protein are present in the S. mansoni gene. The schistosome clone contains the putative site for ADP-ribosylation by cholera toxin found in Gs alpha but does not contain the ADP-ribosylation site for pertussis toxin present in Gi alpha. The amino acids are completely conserved at the GTP-binding sites. On a Northern blot, the cDNA hybridizes to a major band of 3.1 kilobases in RNA from adult schistosomes. The message appears to be absent in miracidia and cercariae, but a faint 3.1-kilobase band is visible in the early schistosomule stage preceding adulthood. This evidence, when added to previous biochemical data, indicates that the expression of this gene is developmentally controlled.

Atrial natriuretic factor and renin synthesized in cultured aortic smooth muscle cells of rats

This study was designed to determine whether or not atrial natriuretic factor (ANF) is present in the vascular walls and to observe the differences in ANF between control (WKY) and stroke-prone spontaneously hypertensive rats (SHRsp). It was found that ANF is indeed present in the vascular wall of the distal aorta. HPLC analysis of the extracts from cultured aortic smooth muscle cells (ASMC) and medium revealed that intracellular ANF was mainly in the form of ANF(1-126), at levels of 0.82 +/- 0.03 (SHRsp) and 1.04 +/- 0.10 ng/10(6) cells (WKY), while the major form in the medium was ANF(99-126), at levels of 0.40 +/- 0.06 and 0.60 +/- 0.06 ng/10(6) cells, respectively. Both forms were present in smaller amounts in SHRsp than in WKY rats. On the contrary, both renin activity and angiotensin I concentrations in SHRsp cells were significantly higher than those in the WKY controls. In addition, immunocytochemistry showed positive ANF staining in cultured ASMC of both strains. The results suggest that ANF can be synthesized and secreted by cultured ASMC from rats.

Structure of HIV-1 reverse transcriptase/DNA complex at 7 A resolution showing active site locations

AIDS, caused by human immunodeficiency virus (HIV), is one of the world's most serious health problems, with current protocols being inadequate for either prevention or successful long-term treatment. In retroviruses such as HIV, the enzyme reverse transcriptase copies the single-stranded RNA genome into double-stranded DNA that is then integrated into the chromosomes of infected cells. Reverse transcriptase is the target of the most widely used treatments for AIDS, 3'-azido-3'-deoxythymidine (AZT) and 2',3'-dideoxyinosine (ddI), but resistant strains of HIV-1 arise in patients after a relatively short time. There are several nonnucleoside inhibitors of HIV-1 reverse transcriptase, but resistance to such agents also develops rapidly. We report here the structure at 7 A resolution of a ternary complex of the HIV-1 reverse transcriptase heterodimer, a monoclonal antibody Fab fragment, and a duplex DNA template-primer. The double-stranded DNA binds in a groove on the surface of the enzyme. The electron density near one end of the DNA matches well with the known structure of the HIV-1 reverse transcriptase RNase H domain. At the opposite end of the DNA, a mercurated derivative of UTP has been localized by difference Fourier methods, allowing tentative identification of the polymerase nucleoside triphosphate binding site. We also determined the structure of the reverse transcriptase/Fab complex in the absence of template-primer to compare the bound and free forms of the enzyme. The presence of DNA correlates with movement of protein electron density in the vicinity of the putative template-primer binding groove. These results have important implications for developing improved inhibitors of reverse transcriptase for the treatment of AIDS.

Protein and nuclear changes in pig eggs at fertilization

The nuclear restructuring that occurs between insemination and full pronuclear formation in pig eggs is accompanied by posttranslational changes to specific egg proteins. Sperm penetration begins in vitro at 3 hr postinsemination (hpi). By 5 hr, decondensing sperm heads and anaphase II plates are observed in 50% of eggs, and, by 8 hpi, both male and female pronuclei have formed. Three consistent changes to the pattern of newly synthesised proteins are triggered in this period; they affect the 46K, 25K, and 22K polypeptides. Changes are also triggered in the 180-200K polypeptides and in the 14K polypeptides, but these are highly variable. The same changes in the prefertilization pattern were observed when prelabelled eggs were used and new protein synthesis was suppressed. The first and most abrupt change involves the apparent catabolic elimination of a group of 46K unphosphorylated polypeptides (pl 7.3-6.4), whose synthesis was greatest before germinal vesicle breakdown but declined slowly in the final phase of maturation, then declined precipitously after activation. Ageing (beyond maturation) also leads to the disappearance of these polypeptides. The progressive disappearance of a set of 25K polypeptides and the concomitant appearance of a dominant 22K polypeptide is the most characteristic fertilization-induced modification to porcine egg proteins. These modifications begin within 1 hr of sperm penetration or activation, are specific to the pig, and involve heavily phosphorylated polypeptides (25K, pl 6.7-6.0) whose synthesis is begun in the early metaphase I stage. Dual ([35S] and [32P]) labelling, protein blocking experiments, and use of alkaline phosphatase suggest that dephosphorylation selectively affects these 25K polypeptides and is mainly or wholly responsible for converting them (completely within 6 hr) to a single, new (22K, pl 7.6) species that is positively charged. The 25K/22K polypeptide modification has a close temporal relationship with the formation of the male and female pronuclei.

Structure of ribonuclease T1 complexed with zinc(II) at 1.8 A resolution: a Zn2+.6H2O.carboxylate clathrate

In order to study the inhibitory effect of Zn2+ on ribonuclease T1 [RNase T1; Itaya & Inoue (1982). Biochem. J. 207, 357-362], the enzyme was cocrystallized with 2 mM Zn2+, pH 5.2, from a solution containing 55% (v/v) 2-methyl-2,4-pentanediol. The crystals are orthorhombic, P2(1)2(1)2(1), a = 48.71 (1), b = 46.51 (1), c = 41.14 (1) A, Z = 4, V = 93203 A3. The crystal structure was determined by molecular replacement and refined by restrained least-squares methods based on Fhkl for 8291 unique reflections with Fo greater than or equal to 1 sigma (Fo) in the resolution range 10 to 1.8 A and converged at a crystallographic R factor of 0.140. The Zn2+ is not bonded to the active site of RNase T1, probably because the His40 and His92 side chains are protonated. Zn2+ occupies the same site as Ca2+ in a series of crystal structures of free and nucleotide-complexed RNase T1. It is coordinated to Asp15 carboxylate and to six water molecules forming a dodecahedron of square antiprismatic form. The Zn2+...O distances are approximately 2.5 A, suggesting that Zn2+ is clathrated and not coordinated, which would require distances of 2.0 A.

Effects of antagonists of protein phosphatases on superoxide release by neutrophils

Neutrophils stimulated with 4 beta-phorbol 12-myristate 13-acetate (PMA) release large quantities of superoxide (O2-) and exhibit phosphorylation of two proteins with molecular masses of 47(p47) and 49 kDa (p49). Addition of inhibitors of protein kinases (e.g. 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7)) to these cells after stimulation with PMA results in the loss of 32P from these proteins and a rapid cessation of O2- release (e.g. Heyworth, P. G., and Badwey, J. A. (1990) Biochim. Biophys. Acta 1052, 299-305). In this paper we report that antagonists of type 1 and 2A protein phosphatases (okadaic acid, calyculin A) prevented both the loss of 32P from p47 and the termination of O2- release in stimulated neutrophils treated with H-7. Calyculin A also caused a remarkable hyperphosphorylation of a number of proteins in neutrophils and increased O2- release from these cells in response to a suboptimal amount of PMA. Enzymes present in both the soluble and particulate fractions of neutrophils catalyzed the near complete dephosphorylation of 32P-labeled p47 and p49 bound to Immobilon-P membranes. Dephosphorylation of these blotted phosphoproteins occurred at physiological rates and was inhibited by okadaic acid and calyculin A. These data strongly suggest that p47 undergoes a continual cycle of phosphorylation and dephosphorylation throughout the period of O2- release when PMA is the stimulus. Moreover, we show that antagonists of type 1 and 2A protein phosphatases block dephosphorylation of p47 both in vivo and in vitro, indicating that these enzymes may modulate O2- release under certain circumstances.

Carcinoid tumor arising in the wall of a congenital bile duct cyst

We report an extremely rare case of carcinoid tumor arising in a congenital choledochal cyst. The dilated choledochal cyst in a 66-year-old Japanese woman was surgically resected, after which the ovoid elevated tumor, measuring 1.5 x 1.5 cm, was detected in the proximal portion of the cyst. A carcinoid tumor was histologically confirmed. To the best of our knowledge, this is the first published case of carcinoid tumor in a choledochal cyst.

[Determination of partially cellular and local immune function in patients with spleen deficiency syndrome]

The immune function status as reflected by the peripheral blood OKT system T cell subset classification and the lymphocyte in vitro interleukin 2 (IL2) secretory function were determined in 30 patients with Spleen deficiency syndrome and 20 normal subjects in this study. Experimental results decreased cellular immune function and disturbance of immune regulatory mechanism in the patients. Its manifestations were decreased number of total T lymphocytes and helper T cells (Th), relatively increased suppressor T cells (Ts), abnormal rate of Th to Ts, no marked change of IL2 secretory function of T cell in vitro, increased SIgA level before stimulating with acid but marked decreased SIgA level after stimulating. All these suggest the compensatory stage of local immune function.

Spindle cell haemangioendothelioma: Probably a benign vascular lesion not a low-grade angiosarcoma

Ten cases of spindle cell haemangioendothelioma (SCH) were analysed clinicopathologically, including an immunohistochemical survey of seven cases and ultrastructural observations on one. There were seven females and three males, ranging from 16 to 76 years of age. All but one lesion developed on the extremities, predominantly on the hands and feet. Six of the ten patients presented multiple nodules or papules which gradually increased in size and number over a long duration. Among them, four patients had undergone operations twice or more, but no metastatic foci were recognized. Histologically, the lesions were composed of dilated vascular spaces and a proliferation of bland-appearing spindle cells and interspersed epithelioid endothelial cells. Ultrastructural and immunohistochemical studies demonstrated that the spindle cells were mainly made up of fibroblastic cells admixed with pericyte-like cells and macrophages. Smooth muscle cells and primitive mesenchymal cells were also present. The clinical and microscopic features suggest that SCH may be a benign vasoformative lesion of a heterochronological multicentric origin.

Crystal structure of ribonuclease T1 complexed with adenosine 2'-monophosphate at 1.8-A resolution

Ribonuclease T1 was purified from an Escherichia coli overproducing strain and co-crystallized with adenosine 2'-monophosphate (2'-AMP) by microdialysis against 50% (v/v) 2-methyl-2,4-pentanediol in 20 mM sodium acetate, 2 mM calcium acetate, pH 4.2. The crystals have orthorhombic space group P2(1)2(1)2(1), with cell dimensions a = 48.93(1), b = 46.57(4), c = 41.04(2) A; Z = 4 and V = 93520 A3. The crystal structure was determined on the basis of the isomorphous structure of uncomplexed RNase T1 (Martinez-Oyanedel et al. (1991) submitted for publication) and refined by least squares methods using stereochemical restraints. The refinement was based on Fhkl of 7,445 reflections with Fo greater than or equal to 1 sigma (Fo) in the resolution range of 10-1.8 A, and converged at a crystallographic R factor of 0.149. The phosphate group of 2'-AMP is tightly hydrogen-bonded to the side chains of the active site residues Tyr38, His40, Glu58, Arg77, and His92, comparable with vanadate binding in the respective complex (Kostrewa, D., Choe, H.-W., Heinemann, U., and Saenger, W. (1989) Biochemistry 28, 7592-7600) and different from the complex with guanosine 2'-monophosphate (Arni, R., Heinemann, U., Tokuoka, R., and Saenger, W. (1988) J. Biol. Chem. 263, 15358-15368) where the phosphate does not interact with Arg77 and His92. The adenosine moiety is not located in the guanosine recognition site but stacked on Gly74 carbonyl and His92 imidazole, which serve as a subsite, as shown previously (Lenz, A., Cordes, F., Heinemann, U., and Saenger, W. (1991) J. Biol. Chem. 266, 7661-7667); in addition, there are hydrogen bonds adenine N6H . . . O Gly74 (minor component of three-center hydrogen bond) and adenosine O5' . . . O delta Asn36. These binding interactions readily explain why RNase T1 has some affinity for 2'-AMP. The molecular structure of RNase T1 is only marginally affected by 2'-AMP binding. Its "empty" guanosine-binding site features a flipped Asn43-Asn44 peptide bond and the side chains of Tyr45, Glu46 adopt conformations typical for RNase T1 not involved in guanosine binding. The side chains of amino acids Leu26, Ser35, Asp49, Val78 are disordered. The disorder of Val78 is of interest since this amino acid is located in a hydrophobic cavity, and the disorder appears to be correlated with an "empty" guanosine-binding site. The two Asp15 carboxylate oxygens and six water molecules coordinate a Ca2+ ion 8-fold in the form of a square antiprism.

[Cloning and sequencing of a highly repeated DNA fragment of rabbit]

We obtained highly repeated DNA fragments from a rabbit by using restriction endonuclease HindIII digestion of chromosomal DNA; the smallest highly repeated DNA fragment was cloned into vector plasmid pUC12. We used the recombinant plasmid to transform E. coli JM101, selected and identified the positive clone by DNA probe in situ hybridization as well as Southern blotting. We obtained a recombinant clone [termed pRAb (Hind III)-1] which contains the highly repeated DNA fragment [termed RAb (Hind III)-1]. The complete nucleotide sequence of the 345bp RAb (Hind III)-1 fragment was determined by the dideoxynucleotide termination sequencing method. We analyzed the characteristics of the structure of the sequence with a microcomputer, and the results suggested that the RAb (Hind III)-1 sequence is quite different from alphoid DNA of primates.