Activated Src tyrosine kinase phosphorylates Tyr-457 of bovine GTPase-activating protein (GAP) in vitro and the corresponding residue of rat GAP in vivo

GTPase-activating protein (GAP) is a key regulator of the cellular Ras protein, which is implicated in oncogenic signal transduction pathways downstream of the viral Src (v-Src) kinase. Previous studies demonstrated that v-Src induces tyrosine phosphorylation of GAP, suggesting that GAP may provide a biochemical link between v-Src and Ras signaling pathways. To determine the precise residues in GAP phosphorylated by Src kinases, we used a baculovirus/insect cell expression system for investigating in vitro phosphorylation of GAP. Phosphopeptide mapping analysis revealed that v-Src and normal cellular Src (c-Src) phosphorylate tyrosine residues in bovine GAP at one major site and one minor site in vitro. Significantly, the major site of GAP phosphorylation in vitro is also the major site of in vivo tyrosine phosphorylation of GAP in rat fibroblasts transformed by v-Src. Analyses of GAP deletion mutants and TrpE-GAP fusion proteins established that Tyr-457 of bovine GAP (and the corresponding residue of rat and human GAP) is the major site of tyrosine phosphorylation. Our results demonstrate that the v-Src kinase induces phosphorylation of the same tyrosine residue of GAP in vitro and in vivo, suggesting that GAP is a direct substrate of activated Src kinases in vivo. Because epidermal growth factor receptor phosphorylates the equivalent tyrosine residue in human GAP (Tyr-460), these findings are consistent with the hypothesis that specific phosphorylation of GAP at this site may have a physiologically important role in regulating mitogenic Ras signaling pathways.

Ocular manifestations of pigmentary disorders

Disorders of pigmentation can result from either an abnormal number of melanocytes, as in nevus of Ota and vitiligo, or an abnormal amount of melanin production, as in albinism. Melanin-producing cells are found in the skin, mucous membranes, uveal tract, and retinal pigment epithelium of the eye and the stria vascularis of the inner ear. Thus, many of the hereditary or congenital pigmentary disorders of the skin are associated with similar pigmentary abnormalities in the eye, such as iris heterochromia or changes in pigmentation of the fundus; however, more commonly, the associated eye finding is a defect in ocular motility, i.e., strabismus and nystagmus, suggesting a concomitant defect in neurologic development. In albinos, the observed neurologic abnormality in the visual pathway and foveal hypoplasia are hypothesized to be related directly to the lack of melanin in the pigment epithelium during development. In acquired disorders of pigmentation, in particular, vitiligo, Vogt-Koyanagi-Harada syndrome, and onchocerciasis, there is a frequent association with uveitis, suggesting an inflammatory cause for the cutaneous pigmentary changes.

Congenital alveolar adhesions

We report an infant girl with congenital alveolar adhesions and a cleft palate. The mucosal bands were resected the day after birth. Stretching exercises of the mandible improved the range of movement at the temporomandibular joint. Two weeks of therapy were required before full mouth opening was possible. Previously reported patients and theories of embryogenesis are reviewed.

Reconstitution of interactions between the Src tyrosine kinases and Ras GTPase-activating protein using a baculovirus expression system

Ras GTPase-activating protein (GAP) has been implicated in mitogenic signal transduction downstream of oncogenic and receptor tyrosine kinases. Previous studies have suggested that GAP is phosphorylated by oncogenic viral Src (v-Src) and that GAP is associated with a complex containing normal cellular Src (c-Src) in vertebrate fibroblasts. To investigate molecular interactions between the Src kinases and GAP, we developed an in vitro system for reconstituting Src-GAP complexes. For this purpose, we constructed recombinant baculovirus vectors that direct expression of Rous sarcoma virus v-Src, chicken c-Src, and bovine GAP in infected Sf9 insect cells. In vitro reconstitution experiments using baculovirus-expressed proteins demonstrate that both v-Src and c-Src associate in complexes with GAP. In addition, in vitro and in vivo phosphorylation analyses indicate that GAP serves as a substrate for both the v-Src and c-Src tyrosine kinases. To determine which structural features of GAP are involved in interactions with the Src kinases, we constructed recombinant baculoviruses that encode deletion mutants of bovine GAP. Deletion of the GAP amino-terminal portion containing Src homology 2 regions, which are highly conserved structural motifs postulated to mediate interactions among proteins, diminishes GAP phosphorylation and association with Src. This reconstitution system should facilitate further studies of molecular interactions between the Src kinases and GAP.

Osmotic and growth-phase dependent regulation of the eta gene of Staphylococcus aureus: a role for DNA supercoiling

Transcriptional fusions were constructed between the promoter for the epidermolytic toxin A (eta) gene of Staphylococcus aureus and the luxAB and xylE reporter gene systems. The expression of the fusion products was found to be dependent upon the accessory gene regulator (agr) locus and was observed to increase significantly during the transition from the exponential to the stationary phase of growth. Furthermore the expression of the eta gene promoter was found to be osmotically regulated, with the expression levels of the eta fusions being inversely related to the osmolyte levels. The ability of environmental factors to influence DNA topology (and thence gene expression) was investigated. High osmolarity (0.7 M NaCl) resulted in an increase in the degree of negative supercoiling of plasmid DNA in the S. aureus strain 8325-4 (Agr+) but not in strain ISP546 (Agr-). Furthermore the eta promoter was strongly induced in S. aureus cultures grown in the presence of sub-inhibitory concentrations of novobiocin, a DNA gyrase inhibitor. However this induction was independent of agr, suggesting that the eta promoter is subject to both agr-dependent (osmolarity, growth phase) and-independent (DNA topology) regulatory processes.

Pneumocystis carinii infection in the middle ear

Pneumocystis carinii is the opportunistic pathogen frequently causing pneumonitis in the acquired immunodeficiency syndrome. Extrapulmonic manifestation of P carinii is unusual and is commonly associated with severe systemic illness, other immune deficiency status, malignancy, or immune suppression. We describe a case of acquired immunodeficiency syndrome with manifestations of P carinii otitis media with severe otalgia and conductive hearing loss.

A novel mitogen-inducible gene product related to p50/p105-NF-kappa B participates in transactivation through a kappa B site

A Rel-related, mitogen-inducible, kappa B-binding protein has been cloned as an immediate-early activation gene of human peripheral blood T cells. The cDNA has an open reading frame of 900 amino acids capable of encoding a 97-kDa protein. This protein is most similar to the 105-kDa precursor polypeptide of p50-NF-kappa B. Like the 105-kDa precursor, it contains an amino-terminal Rel-related domain of about 300 amino acids and a carboxy-terminal domain containing six full cell cycle or ankyrin repeats. In vitro-translated proteins, truncated downstream of the Rel domain and excluding the repeats, bind kappa B sites. We refer to the kappa B-binding, truncated protein as p50B by analogy with p50-NF-kappa B and to the full-length protein as p97. p50B is able to form heteromeric kappa B-binding complexes with RelB, as well as with p65 and p50, the two subunits of NF-kappa B. Transient-transfection experiments in embryonal carcinoma cells demonstrate a functional cooperation between p50B and RelB or p65 in transactivation of a reporter plasmid dependent on a kappa B site. The data imply the existence of a complex family of NF-kappa B-like transcription factors.

Histologic comparison of regeneration in human intrabony defects when osteogenin is combined with demineralized freeze-dried bone allograft and with purified bovine collagen

A bone-inductive protein, osteogenin, has been isolated from long bones of humans and offers promise as a grafting material. Studies, however, suggest that osteogenin must be combined with a bone-derived matrix in order to initiate bone differentiation. The purpose of this study was to determine if osteogenin combined with demineralized freeze dried bone allograft (DFDBA), a bone-derived matrix, and with a bovine tendon-derived matrix will enhanced regeneration of intrabony defects in humans. The tendon-derived matrix and DFDBA used alone served as controls. The ability of each material to form a new attachment apparatus was evaluated independently in submerged and nonsubmerged environments in 2 patient populations. Lymphocyte testing was performed to assess development of an immune reaction to osteogenin. The most apical level of calculus on the root served as the histologic reference point to measure regeneration. Biopsies were obtained at 6 months and regeneration was measured histomorphometrically by 2 blinded evaluators. Serial sections from 36 submerged defects in 8 patients and 50 nonsubmerged defects in 6 patients were submitted for statistical analysis. Mean results indicate that osteogenin combined with DFDBA significantly enhanced regeneration of a new attachment apparatus and component tissues in a submerged environment. DFDBA plus osteogenin and DFDBA alone formed significantly more new attachment apparatus and component tissues than either the tendon-derived matrix plus osteogenin or the tendon-derived matrix alone in both submerged and nonsubmerged environments. There were no significant differences between the tendon-derived matrix plus osteogenin and the tendon-derived matrix alone in either the submerged or nonsubmerged environment. Osteogenin does not impair normal lymphocyte blastogenesis at 6 months postsurgical challenge.

Prokinetic effect of AS-4370 on gastric emptying in healthy adults

The effect of AS-4370 on gastric emptying was investigated in healthy adults using 99mTc-DTPA. Single doses of AS-4370 2.5, 5 or 10 mg or placebo were administered to 12 subjects in a controlled, double-blind, cross-over study. Tests were performed twice weekly in each subject. Thirty min after administration of test drug or placebo, each subject swallowed a bun and orange juice containing 200 microCi nuclide. The radioactivity of the gastric content was measured for 40 min and the activity of the residue was expressed as a percentage of count at the initiation of measurements. The percentage radioactivity, AUC and gastric emptying time fitted by a power exponential curve, were analyzed. No significant difference was observed between the three dose levels of AS-4370 and placebo in half emptying time. However, decreases in the percentage of radioactivity with time were noted; 5 mg at 10 to 16 min and 10 mg at 8 to 24 min after the start of recording. Lower AUCs after 5 mg and 10 mg compared to placebo were also found. The half emptying time was also shorter after 5 mg and 10 mg than placebo. There was no difference in these parameters between 2.5 mg and placebo. The results indicate that AS-4370 5 and 10 mg but not 2.5 mg accelerates gastric emptying in healthy adults.

Mutations that affect the folding of ribose-binding protein selected as suppressors of a defect in export in Escherichia coli

It has been proposed (Randall, L. L., and Hardy, S. J. S. (1986) Cell 46, 921-928) that export of protein involves a kinetic partitioning between the pathway that leads to productive export and the pathway that leads to the folding of polypeptides into a stable conformation that is incompatible with export. As predicted from this model, a decrease in the rate of export of maltose-binding protein to the periplasmic space in Escherichia coli resulting from a defect in the leader sequence was able to be partially overcome by a mutation that slowed the folding of the precursor, thereby increasing the time in which the polypeptide was competent for export. (Liu, G., Topping, T. B., Cover, W. H., and Randall, L. L. (1988) J. Biol. Chem. 263, 14790-14793). Here we describe mutations of the gene encoding ribose-binding protein that were selected as suppressors of a defect in export of that protein and that alter the folding pathway. We propose that selection of such suppressors may provide a general method to obtain mutations that affect the folding properties of any protein that can be expressed and exported in E. coli.

Separation of carbohydrate-mediated microheterogeneity of recombinant human erythropoietin by free solution capillary electrophoresis. Effects of pH, buffer type and organic additives

Free solution capillary electrophoresis has been investigated as an alternative to isoelectric focusing for the separation of the glycoforms of recombinant human erythropoietin (r-HuEPO), a primary regulator of erythropoiesis. A systematic approach was used to study the effect of pH, buffer type and organic modifiers on the resolution of the microheterogeneity of erythropoietin. The main factors for improving the resolution were the regulation of the electroosmotic flow of the running buffer and the reduction of solute-wall interaction. The best resolution of the glycoforms of r-HuEPO was obtained with a mixed buffer pH 4.0 (100 mM acetate-phosphate, 10 h preequilibration time).

Enhanced stability of subtilisin by three point mutations

This study was undertaken to characterize the effect of three point mutations made on aprA-subtilisin on the stability of the protein to both heat- and detergent-induced denaturation. Asparagine residues at positions 109 and 218 were replaced with serine residues to prevent the possible cyclization between these asparagines and the adjacent glycine residues and hence to increase the long-term stability. The effect of these substitutions on conformational stability was examined by thermal denaturation. At high calcium concentrations, the Ser109-substituted analog showed a 3 degrees C higher transition temperature than that of aprA-subtilisin, while the Ser218 substituted analog had a 4 degrees C higher transition temperature. The analog with both changes had a 7 degrees C higher transition temperature than that of the original aprA-subtilisin, indicating that the contributions of the individual mutations were additive. The analog with both mutations also exhibited increased stability in the presence of sodium dodecyl sulfate (SDS) when compared to aprA-subtilisin. In addition to the above two mutations, the asparagine at position 76, located in the high affinity Ca(2+) binding loop of subtilisin, was changed to aspartic acid. The effect of this mutation on the thermal stability of the protein was examined at different calcium concentrations. The analog with all three mutations exhibited little dependence on calcium concentration below 1 mM levels, while the proteins without the mutation at asparagine-76 displayed a strong dependence of melting temperature on Ca(2+) concentration in this range. At much higher calcium concentrations, the analog with three mutations showed an increase in stability similar to that observed with aprA-subtilisin. The analog with three mutations also exhibited greater stability to SDS-induced denaturation than both aprA-subtilisin and the Ser109- and Ser218-substituted analogs. The activation energy barrier for loss of structure in 1% SDS for the analog with all three mutations was increased over that for aprA-subtilisin by 16 kcal/ml. These results suggest that the mutation of asparagine-76 to aspartic acid increases the affinity of the primary Ca(2+) binding site.

Functional role of mucoid exopolysaccharide (alginate) in antibiotic-induced and polymorphonuclear leukocyte-mediated killing of Pseudomonas aeruginosa

We evaluated in vitro the functional role of mucoid exopolysaccharide (MEP) of Pseudomonas aeruginosa in blocking antibiotic-induced and polymorphonuclear leukocyte (PMN)-mediated pseudomonal killing. The serum-resistant P. aeruginosa isolates used were mucoid strain 144MR and its nonmucoid revertant, strain 144NM. By timed kill curves, early bacterial effects of amikacin against mucoid strain 144MR were substantially less than those observed with nonmucoid strain 144NM; this effect was reversible with enzymatic hydrolysis of MEP of strain 144MR by alginase. Also, early tobramycin uptake (15 to 30 min) by mucoid 144MR cells was less than that seen with nonmucoid strain 144NM; pretreatment of 144MR cells with alginase substantially enhanced early tobramycin uptake compared with untreated 144MR cells (P = 0.08). In strain 144NM (but not in strain 114MR) there was a notable postantibiotic leukocidal enhancement effect manifested by increased nonopsonic killing following brief exposure of these cells to supra-MIC amikacin; pretreatment of strain 144MR with alginase rendered these cells more susceptible to amikacin-induced postantibiotic leukocidal enhancement. Similarly, direct PMN-mediated nonopsonic killing of mucoid strain 144MR was significantly less than that observed with strain 144NM (P less than 0.05); pretreatment of 144MR cells with alginase rendered this strain equal to strain 144NM in susceptibility to nonopsonic killing. In addition, exogenous sodium alginate or extracted MEP of strain 144MR interfered with effective nonopsonic killing of strain 144NM by PMNs. Studies also indicated that mucoid strain 144MR was phagocytosed significantly less well than its nonmucoid mate (P less than 0.00001), an effect reversed by pretreatment of the mucoid cells with alginase. These data confirm that P. aeruginosa MEPs functionally decrease the uptake and early bactericidal effect of aminoglycosides in vitro and interfere with effective PMN-mediated nonopsonic phagocytosis and killing of mucoid strains.

Effect of transcription promoters on the optimal production of secreted protein in fed-batch reactors

Production of heterologous proteins by yeast secretion imposes additional factors that need to be considered, which do not appear with production by direct expression. These include additional intracellular polypeptide processing dynamics through the secretory organelles and the protein concentration in the culture medium, which is the usual final destination of the product. Optimal control theory is applied to optimize fed-batch production of secreted protein. We maximize an objective function that includes both total production rate and product concentration. A mutant invertase is chosen as the model heterologous secretory protein. Optimal control control strategies have been obtained for the use of two different promoters for the gene transcription, a dere-pressible SUC2 promoter and a strong glycolytic GPD promoter. With the use of the strong GPD promoter, achieving maximum production occurs on the singular arc of maximum specific growth rate. As the object switches to maximum product concentration, operation occurs for longer periods of time at a slow glucose singular arc condition. The optimal control for maximizing protein production with the weak SUC2 promoter requires transitions between high and low glucose concentrations associated with multiple distinct singular arc conditions. For maximum product concentration, the high concentration branches of the singular arc supporting maximum growth rate and maximum secretion rate disappear. Operation stays essentially on the low glucose concentration branch of the singular arc, which maximizes the protein production rate and minimizes the dilution of the broth product concentration.

TDAT--time domain analysis tool for EEG analysis

An interactive design and analysis tool for displaying and quantifying multiple channels of data is presented. The system allows one to easily visualize multiple data channels and simultaneously observe the effects of filters on the data and to evaluate signal detection algorithms. The software is designed for a workstation environment; it will find application in a variety of applications where one needs to simultaneously visualize multiple data channels. TDAT is being used for the design and evaluation of filters and detection algorithms for electroencephalogram (EEG) waveforms, and it is serving as a prototype of a paperless system to be used by electroencephalographers. This paper describes the general software structure of the system and illustrates many of the system features with examples.

[Successful treatment by using a pedicled omental flap for mediastinal infection in the presence of a external valved conduit]

Mediastinal infection is one of serve and fatal complications after cardiac surgery, especially in the presence of an artificial graft. A case of successful treatment by using a pedicled omental flap for mediastinal infection in the presence of an external valved conduit is reported. a 10-year-old girl who had implanted the 12 mm porcine valved conduit for truncus arteriosus at age 9 months, underwent replacement of the old conduit with a 18 mm valved conduit. On the 9th postoperative day, as soon as mediastinal infection was proved by positive culture of the drainage from the chest tube, a reoperation was performed to debride and irrigate the mediastinum. Irrigation with povidone-iodine and antibiotics was continued for 3 weeks until improvement of CRP levels and negative drainage cultures. Then the heart and the valved conduit were wrapped with the pedicled omental flap and the skin was closed. She was without any evidence of infection for 3 months after operation. Use of a pedicled omental flap might be an effective method for treatment of mediastinal infection in the presence of an external conduit.

Drug testing at the 10th Asian Games and 24th Seoul Olympic Games

Drug testing (doping test) procedures in the 1986 10th Asian Olympic Games and 1988 24th Seoul Olympic Games are reported. The International Olympic Committee Medical Commission (IOC-MC) conducted its first doping tests at the 1968 Olympics in Grenoble. With the guidance of the International Olympic Committee (IOC), the Olympic Council of Asia (OCA) introduced doping tests at the 1986 10th Asian Olympic Games in Seoul, Korea, September 21st to October 5th, 1986. 585 samples were tested at the Doping Control Center, Korea Advanced Institute of Science and Technology (DCC/KAIST), for stimulants, narcotics, anabolic steroids, and beta-blockers by gas chromatography/mass spectrometry, high pressure liquid chromatography, and fluorescence polarization immunoassay. These tests covered about 100 different drugs and another 400 as metabolites in addition to pharmacologically related substances. For the Seoul Olympic Games from September 17 to October 2, 1988, the IOC-MC with the DCC/KAIST conducted doping tests on 1601 samples for stimulants, narcotics, beta-blockers, diuretics, and anabolic steroids using GC, HPLC, GC/MSD, GC/MS, LC/MS, and TDx.

Vertical dimensional changes of the lips in the North American black patient after four first-premolar extractions

The purpose of this investigation was to evaluate the vertical dimensional changes of the lips in the North American black patient after four first-premolar extractions. A sample of 15 patients treated at the Orthodontic Clinic of Howard University College of Dentistry was selected. Pretreatment and posttreatment lateral cephalograms were traced on acetate tracing paper: landmarks of the skeletal and soft tissues were identified, and angular and linear measurements were made. Changes in the vertical dimensions of the lips used the Frankfort horizontal as a reference plane and changes in the horizontal dimensions of the lips used the pterygoid plane as a reference plane. Statistical significance was tested by means of two-tailed t tests and Pearson's r correlations. Findings indicated that retraction of the maxillary incisors correlated with an increase in upper lip depth, an increase in interlabial vertical dimension, and an increase in the inferomentolabial angle. The increase in interlabial vertical dimension correlated with an increase in the horizontal dimension of the upper lip relative to upper incisor retraction. This increase in interlabial vertical dimension relative to upper incisor retraction differed significantly from the results of the study by Jacobs1 on a sample of white patients treated with four first-premolar extractions. It is necessary to investigate this difference in future studies using larger sample sizes.

Coagulopathy in hemorrhagic fever with renal syndrome (Korean hemorrhagic fever)

The pathophysiology of bleeding manifestations in hemorrhagic fever with renal syndrome (HFRS) was elucidated by serially evaluating coagulation and fibrinolytic profiles and complement alterations in patients with HFRS. In the early stage of the disease, platelet counts, platelet survival time, and platelet aggregation in vitro decreased. Prolongation of bleeding time, prothrombin time, and activated partial thromboplastin time was noted, with decreases in coagulation factors II, V, VIII, IX, and X. Levels of fibrinogen were decreased, and those of fibrinogen-fibrin degradation products in serum and urine were increased. Concentrations of plasminogen, alpha 2-plasmin inhibitor, and antithrombin III in plasma were depressed. Procoagulant activity was present in plasma. Circulating immune complexes were found, whereas serum levels of C3 were decreased. In the early stage of HFRS, thrombocytopenia, defects in platelet function, and disseminated intravascular coagulation may play central roles in the pathogenesis of bleeding manifestations. Vasculopathy and immunologic aberrations also may play a role.

Demonstration of single chain urokinase-type plasminogen activator on human platelet membrane

Fibrinolytic activity was found to be associated with sonicated platelet membranes after separation from cytosol by differential centrifugation. This fibrinolytic activity was attributed to the presence of a plasminogen activator, which was immunochemically identified as urinary-type plasminogen activator (uPA) by antibody neutralization assay, immunoblotting, and immunofluorescence. The molecular weight (mol wt) of this uPA was 54,000 and was present as the single chain form, although a small amount was detected in a higher mol wt complex indicative of a uPA-inhibitor complex. Treatment of membrane preparations with Triton X-100, 3 mol/L KCl, and 0.1 mol/L glycine, (pH 2.3), but not 10 mmol/L ethylenediamine tetraacetic acid (EDTA), removed the uPA from the membrane. This suggests that uPA is a peripheral membrane protein and that metal ions do not mediate protein-membrane association. Immunofluorescent staining revealed the presence of uPA on the outer surface of the platelet in preparations of intact unstimulated platelets. Thus, uPA is associated with the outer leaflet of the platelet membrane and may be involved with the acceleration of thrombus degradation observed with platelet-rich thrombi.

Refractoriness to platelet transfusion after single-donor consecutive platelet transfusions and its relationship to platelet antibodies

In thirty patients with acute leukemia and severe aplastic anemia receiving random single donor platelet transfusions, the development of refractoriness by consecutive platelet transfusions with cytapheresis and its relationship to the appearance of anti-platelet antibodies were investigated. The median number of platelet transfusions inducing refractoriness was 13 times, and 20% of the patients remained unrefractory despite of the repeated multiple platelet transfusions up to 20 to 25 times. The results of anti-platelet antibody tasts by the enzyme-linked immunosorbent assay(ELISA) and immunofluorescent techniques(IFT) showed no statistically significant relationship with the refractoriness (p greater than 0.1). Although there was significant correlation between the results of ELISA and IFT, both tests were insufficient to find out refractoriness even with the use of pooled platelets from multiple donors as target cells. This study shows that 13 single donor platelet transfusions result in refractoriness, that both ELISA and IFT are insufficient to detect refractoriness despite of their significant correlation, and that other methods than these are needed in order to detect alloimmunization.

Serological identification of thymocyte differentiation antigens

We have examined subfractions of human thymocytes for the expression of novel differentiation antigens. Non-HLA alloantisera procured from multiparous women served as antibody probes. Thymocytes from five individuals were sequentially separated by discontinuous Percoll density gradient centrifugation and a peanut agglutinin (PNA) panning technique. Subfractions were selected and examined for their relative intensity of HLA class I and CD1 antigens as determined by cytofluorometric analysis. Two subfractions were characterized as follows: an immature population (Fr6 PNA-) expressed a high level of CD1 (OKT6 binding) antigen and a low level of class I HLA antigen; and a more mature fraction (Fr3 PNA-) expressed minimal amounts of CD1 antigen and relatively high levels of HLA class I molecules. Fr6 PNA+ and Fr3 PNA- thymocytes were tested for their reactivity with a panel of non-HLA alloantibodies as determined by cytofluorometric analysis. We observed that three alloantibodies demonstrated strong fluorescence staining with Fr6 PNA+ thymocytes only, whereas three other alloantibodies reacted with both the Fr6 PNA+ and the Fr3 PNA- subfractions. All six alloantibodies failed to react with peripheral T cells. However, the six antibodies did react with a panel of cultured T lymphoblastoid leukemic cells and fresh leukemic T cells. Blocking studies demonstrated that these alloantibodies do not bind beta 2-microglobulin-associated determinants. These results suggest that the alloantibodies detect thymocyte differentiation antigens (TDA) that are shared by or are cross-reactive with antigens expressed on certain leukemia T cells. The non-beta 2m-associated TDA antigens are not expressed on normal resting T cells.

Cyclic GMP-phosphodiesterase of rd retina: biosynthesis and content

Deficient cGMP-phosphodiesterase (cGMP-PDE) activity results in elevated levels of cGMP in the rd retina before any pathological signs are observed. Since the enzyme is present in rd retina, although it is barely activated by light, we determined whether its synthesis starts at the same time as that of cGMP-PDE in normal retina, or if either its synthesis is halted or degradation of the enzyme increases before the degeneration of the visual cells. We found that synthesis of cGMP-PDE in rd retina is comparable with that in normal retina while the photoreceptors are viable but that cGMP-PDE content is lower than that of normal retina before the visual cells begin to degenerate. Our results suggest that cGMP-PDE is more susceptible to degradation in rd than in normal photoreceptors or, alternatively, that proteolytic enzyme(s) involved in the degradation of cGMP-PDE are in higher concentration or more active in the defective than in the normal retina.

Modulation of folding pathways of exported proteins by the leader sequence

Leader peptides that function to direct export of proteins through membranes have some common features but exhibit a remarkable sequence diversity. Thus there is some question whether leader peptides exert their function through conventional stereospecific protein-protein interaction. Here it is shown that the leader peptides retarded the folding of precursor maltose-binding protein and ribose-binding protein from Escherichia coli. This kinetic effect may be crucial in allowing precursors to enter the export pathway.

Protein kinase C in the regulation of smooth muscle contraction

The cellular and molecular mechanisms underlying smooth muscle contraction are reviewed in the light of recent studies of smooth muscle ultrastructure and of the role of polyphosphoinositide turnover and protein kinase C function in smooth muscle contraction. A new model of smooth muscle contraction is proposed that differs radically from accepted views, particularly the latch bridge hypothesis, in terms of both Ca2+ messenger function and the molecular events underlying this process. A coordinate fibrillar domain model of contraction is proposed in which the initial and sustained phases of contraction are mediated by different cellular and molecular events. The initial phase of response is mediated by a rise in [Ca2+]c and the resulting calmodulin-dependent activation of both myosin light chain kinase and the dissociation of caldesmon from the actin-caldesmon-tropomyosin-myosin fibrillar domain. These events lead to an interaction between actin and the phosphorylated light chains of myosin just as in previous models. However, this initial phase is followed by a sustained phase in which a rise in [Ca2+]sm stimulates the plasma membrane-associated, Ca2+-sensitive form of protein kinase C that results in the phosphorylation of both structural and regulatory components of the filamin-actin-desmin fibrillar domain. These events underlie the tonic phase of contraction.

Percutaneous endoscopic gastrostomy for enteral nutrition

From January to October, 1986, at Wonkwang University Hospital in Iri, percutaneous endoscopic gastrostomy(PEG) was attempted in 26 patients and was successful in 24. This study was designed to review the technique and to evaluate the efficacy of PEG. The mean operation time was 22 minutes (range: 14 to 42 minutes). After feeding started, early positive nitrogen balance was achieved in all patients. All gastrostomies functioned well throughout the patient’s survival with the longest functioning at 10 month. There were no procedure-related deaths, and morbidity was lower and less severe as compared with large-bore nasogastric tube feeding. Complications included minor wound infection in two patients, stomal growth in one patient, leaks around the tube in two patients, and intraperitoneal leak in one patient. No patient developed aspiration pneumonia or required laparotomy for complications from PEG. The gastrostomy tube was easily removed endoscopically when treatment was completed. Feeding via a large-bore tube increased the risk of aspiration pneumonia (72%) and the feeding cost via a small-bore tube with elemental diet exceeded that of PEG by more than tenfold. This author’s experience with these 26 patients has led to the conclusion that PEG is safe, easy to perform, and effective means of creating feeding gastrostomy without laparotomy or general anesthesia. The authors suggest that PEG be the preferred route of alimentation in those patients who are unable to swallow for prolonged periods of time.

Carbachol-induced protein phosphorylation changes in bovine tracheal smooth muscle

The changes in protein phosphorylation associated with bovine tracheal smooth muscle contraction were studied by labeling intact muscle strips with [32P]PO4(3-) and analyzing the phosphoproteins by two-dimensional gel electrophoresis. Among 20 to 30 phosphoproteins resolvable with the two-dimensional electrophoresis system, the phosphorylation of 12 proteins was reproducibly affected by treatment with carbachol, in a time-dependent manner. Five of these proteins have been identified as 20-kDa myosin light chain, caldesmon, synemin, and two isoelectric variants of desmin. The other 7 are low molecular weight (Mr less than 40,000) cytosolic proteins. One cytosolic protein and myosin light chain are quickly but transiently phosphorylated by carbachol, the peak of myosin light chain phosphorylation being at about 1 min after agonist addition. In contrast, both variants of desmin, synemin, caldesmon, and 5 cytosolic proteins are phosphorylated at varying rates and remain phosphorylated for the duration of carbachol action. These "late" phosphorylation changes occur simultaneously with the dephosphorylation of one cytosolic protein. These carbachol-induced phosphorylation changes, like the contractile response, appear to be calcium-dependent. The addition of 12-deoxyphorbol 13-isobutyrate, a protein kinase C activator, causes a dose-dependent, sustained contraction of tracheal smooth muscle which develops more slowly than that induced by carbachol. This contractile response is associated with the same protein phosphorylation changes as those observed after prolonged carbachol treatment. In contrast, forskolin, an adenylate cyclase activator and a potent smooth muscle relaxant, induces the phosphorylation protein 3 and one variant of desmin. These observations strongly suggest that different phosphoproteins may be mediators of tension development and tension maintenance in agonist-induced contraction of tracheal smooth muscle.

Procoagulant activity and thrombelastography in Korean hemorrhagic fever

Twenty male patients with Korean hemorrhagic fever were evaluated with thrombelastography (TEG) to assess the changes in coagulation system, and the results were compared with those of conventional coagulation tests. Procoagulant activity in the plasma was determined by comparing the reaction time "r" of the normal plasma and that of the mixture of equal parts of the normal plasma and the patient's plasma. The TEG was found to be a useful measure of the changes in the coagulation profile, and provided instant accurate assessment of the patient's hemostatic function. Presence of the procoagulant activity was demonstrated in the plasma of the patients and indicated occurrence of active intravascular coagulation during the early stage of the disease.

Hostility and recovery from melancholia

Twenty inpatients suffering from major depressive illness with melancholia were administered the hostility subscale of the Kellner Symptom Questionnaire and Paykel's Clinical Interview for Depression before and after treatment with amitriptyline. A matched control group of normal subjects had the same assessments at two points in time. Hostility decreased and friendliness increased in depressives after amitriptyline; upon recovery, there were no significant differences in hostility between depressed patients and control subjects, whereas such differences were striking during the illness. Patients who had reported losses before onset of illness rated themselves as more friendly than the other depressives; their hostility did not significantly decrease with recovery. The results suggest that hostility improves with the treatment of depression; life events appear to influence the degree of hostility in depressive illness as well as the response to treatment.

Rating depression in normals and depressives: observer versus self-rating scales

Different methods of assessing depression and anxiety were tested in 20 patients suffering from a major depressive disorder with melancholia and 20 matched control subjects. Depressives were assessed before and after treatment with amitriptyline and normals were retested at the same interval. The scales used were: Paykel's Clinical Interview for Depression--which is an expanded version of the Hamilton Depression Rating Scale; the Brief Depression Rating Scale; and Symptom Questionnaire (SQ). All scales discriminated sensitively between patients and normals and the scores changed substantially with treatment. Except for the well-being subscales of the SQ, the scales showed an adequate test-retest reliability in normals. Although all scales were suitable for the measurement of depression, they differed in psychometric properties. For example, the Depression subscale of the SQ showed an unusually high test-retest reliability in normals, whereas the Contentment subscale was unreliable. Yet, the latter has been found to be highly sensitive in detecting differences between the effects of psychotropic drugs and placebo in drug trials, so it appears to measure sensitively a fleeting mood. The combined use of all three scales in patients with affective disorders yields information that might not be revealed if only one scale is used.

Antineoplastic activity of 3'-(chloroethyl)nitrosourea analogues of 2'-deoxyuridine and 2'-deoxy-5-fluorouridine

The (chloroethyl)nitrosourea analogues of 2'-deoxyuridine and 2'-deoxy-5-fluorouridine, 3'-[3-(2-chloroethyl)-3-nitrosoureido]-2',3'-dideoxyuridine (3'-CdUNU, 7) and 3'-[3-(2-chloroethyl)-3-nitrosoureido]-2,3'-dideoxy-5-fluorouridine (3'-CFdUNU, 8), have been synthesized by treatment of the corresponding 3'-amino nucleosides with chloroethyl isocyanate, followed by nitrosation of the resulting ureas. Nucleoside nitrosoureas 7 and 8 exhibited marked anticancer activity against L1210 leukemia in tumor-bearing mice. At an optimum dosage level of 40 mg/kg, 7 and 8 produced 90% and 60% "cures" (greater than 60-day survivors), respectively. The structure-activity relationships are discussed.

Seroepidemiology of human T-cell leukemia virus type-I in the Republic of Korea

We investigated the prevalence of antibodies to human T-cell leukemia virus type I (HTLV-I) associated antigens in various patients and healthy individuals in the Republic of Korea. Seventeen out of 6,255 individuals (0.27%) were seropositive. The positive rate in males was 0.21% and that in females was 0.36%, the sex difference being similar to that in endemic areas in Japan. HTLV-I carriers were found in Seoul and neighboring areas, but not in Busan city or Jeju Island, which are adjacent to Kyushu, Japan. The prevalence of sera with definite anti HTLV-I antibodies seems to be very low in the Republic of Korea.

A signal sequence mutant defective in export of ribose-binding protein and a corresponding pseudorevertant isolated without imposed selection

Ribose-binding protein is exported to the periplasmic compartment of Escherichia coli by a process that involves proteolytic cleavage of an amino-terminal extension of amino acids from the precursor form of the protein. In a collection of mutants isolated as defective in the Rbs transport system, a strain was identified that contained only precursor ribose-binding protein, none of which was exported to its normal location in the periplasm. The mutated rbsB contained a base substitution that results in a change of leucine to a proline at position-17 in the signal sequence. A pseudorevertant of the mutant contained proteolytically processed, active ribose-binding protein in the periplasm. The pseudorevertant rbsB carried a second mutation: serine at position-15 in the signal sequence was changed to phenylalanine. Isolation of a signal sequence mutant and a corresponding pseudorevertant without specific selection or site-directed mutagenesis emphasizes the possibility of obtaining export mutants without the use of procedures that could bias or limit the range of mutations found. Explanation of the extreme phenotype of the mutant and the effective correction of that phenotype in the pseudorevertant requires extension of current notions of critical features of signal sequences.

Detection and quantitation of low levels of protected and unprotected (R)-amino acids in the synthesis of thymopentin, an immunoregulatory peptide

Two chiral chromatographic procedures (HPLC and capillary GC) were developed to monitor the extent of epimerization of protected and unprotected amino acids used in a synthesis of thymopentin, an immunoregulatory peptide currently in clinical trials. The capillary GC method allowed the detection of the (R)-enantiomer in the presence of the (S)-enantiomer at levels of greater than or equal to 0.2%, while the HPLC method allowed similar detection at levels of greater than or equal to 0.1%.

Safety of cefotaxime and other new beta-lactam antibiotics

beta-Lactam antimicrobial agents have until recently enjoyed a reputation of reliability and safety. Now serious problems have emerged associated with use of some of the newer drugs of this class. Latamoxef (moxalactam) and cefoperazone, both of which have a methyltetrazolethiol side chain, have been reported to cause coagulation abnormalities, clinical bleeding, and disulfiram-like reactions. In addition, an unusually high incidence of diarrhoea has been associated with administration of cefoperazone. Cefotaxime does not have the [methylthiotetrazole] side chain and has not caused bleeding, coagulopathy, or disulfiram-like reactions. Diarrhoea, usually mild, has been observed in only 1% of patients given cefotaxime in clinical trials. The remarkable safety record of cefotaxime is an important consideration for clinicians in the selection of an antimicrobial agent for seriously ill patients.

Regulation of thyroid ornithine decarboxylase by the polyamines. Induction of a protein inhibitor of ornithine decarboxylase by the end-products of the reaction

When spermidine, putrescine or 1,3-diaminopropane was injected (12.5 mumol/100 g body weight) into rats 1 h before thyrotropin, ornithine decarboxylase activity was increased by 75--150% over control levels. However, when greater than or equal to 75 mumol polyamine/100 g body weight was injected, thyrotropin-activated activity was inhibited by 70--95%. Multiple polyamine injections inhibited goitrogen-induced activity and gland weight increase by approx 35%. The polyamines also inhibited thyrotropin-activated rat thyroid ornithine decarboxylase in vitro in a dose-related fashion, with 50% inhibition occurring at 2--5 . 10(-4)M. The inhibition was not due to a direct effect on the enzyme. No stimulation was seen with low concentrations of polyamine. The polyamines had no effect on in vitro thyroid protein/RNA synthesis or glucose oxidation but had a biphasic effect on plasma membrane adenylate cyclase activity. A protein inhibitor to thyroid ornithine decarboxylase was generated in vivo by multiple injections of the polyamines into rats and in vitro by incubating bovine thyroid slices with 2--10 mM polyamine. The inhibitor was non-dialyzable, destroyed by boiling, and its formation was blocked in a dose-related fashion by cycloheximide. We conclude that: (1) thyroid ornithine decarboxylase is subject not only to positive control, but is also negatively regulated by its end-products, the polyamines, which induce a protein inhibitor to ornithine decarboxylase; (2) since gland growth is also inhibited under these conditions, the polyamine effect on thyroid ornithine decarboxylase may be biologically significant.