Actin critical concentration optimizes at intermediate [cytochalasin B]/[actin] ratios

Effect of cytochalasin B on actin critical concentration has been assayed using the fluorescence enhancement of pyrene-labeled actin. A peak effect of cytochalasin B on the critical concentration is observed in the presence of either 100 mM K+, or 100 mM K+ plus 2 mM Mg2+. This may result from two competing activities of cytochalasin B, one associated with its capping activity to the barbed end of actin filaments, and the other associated with its lateral binding site(s) along the filaments resulting in a severing activity of cytochalasin B.

The carriage of Escherichia coli resistant to antimicrobial agents by healthy children in Boston, in Caracas, Venezuela, and in Qin Pu, China

BACKGROUND AND METHODS

The healthy members of a community represent its largest reservoir of bacteria resistant to antimicrobial agents. We compared the resistance to eight agents of Escherichia coli in stool samples from untreated, healthy children in cities on three continents.

RESULTS

When screened by a selective method that detected 1 resistant colony in 10,000 colonies, nearly half the children in Boston (18 of 39) had no resistant colonies--a finding consistent with the findings of other surveys performed in developed countries. However, all but 1 of 41 children screened in Caracas, Venezuela, and all but 2 of 53 in Qin Pu, China, carried resistant strains. Only 1 child in Boston but 25 in Caracas and 34 in Qin Pu carried strains resistant to trimethoprim. None of the children in Boston or Caracas but 17 in Qin Pu carried strains resistant to gentamicin. Among 10 colonies selected randomly from each stool sample, the average frequency of resistance in Caracas was 3.6 times greater than in Boston, and that in Qin Pu was 5.3 times greater. There was resistance to five or more antimicrobial agents in 20 percent of the Qin Pu strains and in 6 percent of the Caracas strains but in none of the Boston strains.

CONCLUSIONS

In addition to clinical isolates, as reported previously, the bacteria that colonize health children in the community may be resistant far more often in some regions than in others. A low rate of carriage of antimicrobial resistance in the community should become a public health goal.

Inhibition of mitochondrial respiration by analogues of the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium: structural requirements for accumulation-dependent enhanced inhibitory potency on intact mitochondria

Analogues of 1-methyl-4-phenylpyridinium (MPP+), the neurotoxic metabolite of the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, were evaluated for inhibition of respiration in intact mitochondria (Mw) and in electron transport particles (ETP). MPP+ exhibits relatively weak inhibitory activity in ETP, but potent inhibition in Mw occurs on account of its energy-dependent accumulation inside mitochondria. The permeant anion tetraphenylborate potentiates the inhibition in both Mw and ETP. Replacement of the 4-phenyl ring of MPP+ by a variety of aromatic and nonaromatic rings, and of the N-methylpyridinium group by other cationic aromatic heterocycles, preserves the inhibitory patterns seen for MPP+. The general observation of enhanced inhibitory potency in Mw for all these permanently charged cations is consistent with our contention that energy-dependent accumulation inside mitochondria represents a passive Nernstian concentration in response to the transmembrane electrochemical gradient. Nonetheless, the magnitude of the inhibitory potentiation seen in Mw relative to ETP varies widely with structure. In particular, less lipophilic analogues, especially those bearing a localized, rather than resonance-stabilized, permanent positive charge, exhibit similar inhibitory activity to MPP+ in ETP, but the inhibition in Mw is not comparably enhanced. For these same analogues, the inhibitory activity in ETP is only weakly potentiated by tetraphenylborate. Since succinate was found to completely reverse the respiratory inhibition in Mw induced by all types of MPP+ analogues investigated, a common site 1 inhibition appears to be involved; thus the different inhibitory patterns observed must be due to structural factors governing membrane transport and distribution properties.

Epstein-Barr virus nuclear antigen 2 transactivates latent membrane protein LMP1

Several lines of evidence are compatible with the hypothesis that Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA-2) or leader protein (EBNA-LP) affects expression of the EBV latent infection membrane protein LMP1. We now demonstrate the following. (i) Acute transfection and expression of EBNA-2 under control of simian virus 40 or Moloney murine leukemia virus promoters resulted in increased LMP1 expression in P3HR-1-infected Burkitt's lymphoma cells and the P3HR-1 or Daudi cell line. (ii) Transfection and expression of EBNA-LP alone had no effect on LMP1 expression and did not act synergistically with EBNA-2 to affect LMP1 expression. (iii) LMP1 expression in Daudi and P3HR-1-infected cells was controlled at the mRNA level, and EBNA-2 expression in Daudi cells increased LMP1 mRNA. (iv) No other EBV genes were required for EBNA-2 transactivation of LMP1 since cotransfection of recombinant EBNA-2 expression vectors and genomic LMP1 DNA fragments enhanced LMP1 expression in the EBV-negative B-lymphoma cell lines BJAB, Louckes, and BL30. (v) An EBNA-2-responsive element was found within the -512 to +40 LMP1 DNA since this DNA linked to a chloramphenicol acetyltransferase reporter gene was transactivated by cotransfection with an EBNA-2 expression vector. (vi) The EBV type 2 EBNA-2 transactivated LMP1 as well as the EBV type 1 EBNA-2. (vii) Two deletions within the EBNA-2 gene which rendered EBV transformation incompetent did not transactivate LMP1, whereas a transformation-competent EBNA-2 deletion mutant did transactivate LMP1. LMP1 is a potent effector of B-lymphocyte activation and can act synergistically with EBNA-2 to induce cellular CD23 gene expression. Thus, EBNA-2 transactivation of LMP1 amplifies the biological impact of EBNA-2 and underscores its central role in EBV-induced growth transformation.

The histopathological pattern of primary IgA nephropathy in a Malaysian patient population

In the 10-year period from October 1977 to July 1987, 149 cases of primary IgA nephropathy were histologically confirmed through renal biopsies in the Department of Pathology, University Hospital, Kuala Lumpur. The ages of these patients ranged from 5 to 72 years, with the majority in the 20-30 year age group. There was no sex preponderance. The ethnic distribution showed a significant predominance of Chinese with 107 (71.8%) Chinese, 24 (16.1%) Malays, 15 (10.1%) Indians and 3 others. A wide range of renal glomerular pathology was seen, the commonest being diffuse mesangioproliferative glomerulonephritis (59.1%). Focal proliferative glomerulonephritis (14.1%) followed by minimal change glomerulonephritis (10.7%) were next in order of frequency. Immunofluorescence studies consistently demonstrated heavy and predominant IgA deposition in the mesangium. Weak deposition of C3, IgG and IgM were also observed in various combinations.

Epstein-Barr virus latent membrane protein (LMP1) and nuclear proteins 2 and 3C are effectors of phenotypic changes in B lymphocytes: EBNA-2 and LMP1 cooperatively induce CD23

Latent Epstein-Barr virus (EBV) infection and growth transformation of B lymphocytes is characterized by EBV nuclear and membrane protein expression (EBV nuclear antigen [EBNA] and latent membrane protein [LMP], respectively). LMP1 is known to be an oncogene in rodent fibroblasts and to induce B-lymphocyte activation and cellular adhesion molecules in the EBV-negative Burkitt's lymphoma cell line Louckes. EBNA-2 is required for EBV-induced growth transformation; it lowers rodent fibroblast serum dependence and specifically induces the B-lymphocyte activation antigen CD23 in Louckes cells. These initial observations are now extended through an expanded study of EBNA- and LMP1-induced phenotypic effects in a different EBV-negative B-lymphoma cell line, BJAB. LMP1 effects were also evaluated in the EBV-negative B-lymphoma cell line BL41 and the EBV-positive Burkitt's lymphoma cell line, Daudi (Daudi is deleted for EBNA-2 and does not express LMP). Previously described EBNA-2- and LMP1-transfected Louckes cells were studied in parallel. EBNA-2, from EBV-1 strains but not EBV-2, induced CD23 and CD21 expression in transfected BJAB cells. In contrast, EBNA-3C induced CD21 but not CD23, while no changes were evident in vector control-, EBNA-1-, or EBNA-LP-transfected clones. EBNAs did not affect CD10, CD30, CD39, CD40, CD44, or cellular adhesion molecules. LMP1 expression in all cell lines induced growth in large clumps and expression of the cellular adhesion molecules ICAM-1, LFA-1, and LFA-3 in those cell lines which constitutively express low levels. LMP1 expression induced marked homotypic adhesion in the BJAB cell line, despite the fact that there was no significant increase in the high constitutive BJAB LFA-1 and ICAM-1 levels, suggesting that LMP1 also induces an associated functional change in these molecules. LMP1 induction of these cellular adhesion molecules was also associated with increased heterotypic adhesion to T lymphocytes. The Burkitt's lymphoma marker, CALLA (CD10), was uniformly down regulated by LMP1 in all cell lines. In contrast, LMP1 induced unique profiles of B-lymphocyte activation antigens in the various cell lines. LMP1 induced CD23 and CD39 in BJAB; CD23 in Louckes; CD39 and CD40 in BL41; and CD21, CD40, and CD44 in Daudi. In BJAB, CD23 surface and mRNA expression were markedly increased by EBNA-2 and LMP1 coexpression, compared with EBNA-2 or LMP1 alone. This cooperative effect was CD23 specific, since no such effect was observed on another marker, CD21.(ABSTRACT TRUNCATED AT 400 WORDS)

[Pharmacological studies of huomaisan]

After per os Huomaisan twice a day for 5 days, HMS significantly prolonged thrombus formation time and inhibited platelet aggregation induced by ADP and collagen. Meanwhile, HMS also decreased blood viscosity, but did not significantly affect hematocrit. The result shows that HMS has multiple actions on blood.

Epstein-Barr virus nuclear antigen 2 induces expression of the virus-encoded latent membrane protein

Infection of Epstein-Barr virus-negative human B-lymphoma cell lines with the fully transforming B95.8 Epstein-Barr virus strain was associated with complete virus latent gene expression and a change in the cell surface and growth phenotype toward that of in vitro-transformed lymphoblastoid cell lines. In contrast, the cells infected with the P3HR1 Epstein-Barr virus strain, a deletion mutant that cannot encode Epstein-Barr nuclear antigen 2 (EBNA2) or a full-length EBNA-LP, expressed EBNAs1, 3a, 3b, and 3c but were negative for the latent membrane protein (LMP) and showed no change in cellular phenotype. This suggests that EBNA2 and/or EBNA-LP may be required for subsequent expression of LMP in Epstein-Barr virus-infected B cells. Recombinant vectors capable of expressing the B95.8 EBNA2A protein were introduced by electroporation into two P3HR1-converted B-lymphoma cell lines, BL30/P3 and BL41/P3. In both cases, stable expression of EBNA2A was accompanied by activation of LMP expression from the resident P3HR1 genome; control transfectants that did not express the EBNA2A protein never showed induction of LMP. In further experiments, a recombinant vector capable of expressing the full-length B95.8 EBNA-LP was introduced into the same target lines. Strong EBNA-LP expression was consistently observed in the transfected clones but was never accompanied by induction of LMP. The EBNA2A gene transfectants expressing EBNA2A and LMP showed a dramatic change in cell surface and growth phenotype toward a pattern like that of lymphoblastoid cell lines; some but not all of these changes could be reproduced in the absence of EBNA2A by transfection of P3HR1-converted cell lines with a recombinant vector expressing LMP. These studies suggest that EBNA2 plays an important dual role in the process of B-cell activation to the lymphoblastoid phenotype; the protein can have a direct effect upon cellular gene expression and is also involved in activating the expression of a second virus-encoded effector protein, LMP.

Plasma gamma-aminobutyric acid in experimental fulminant hepatic failure of rats and its diagnostic value in hepatic encephalopathy

The plasma concentration of gamma-aminobutyric acid (GABA) was measured by radioreceptor assay in galactosamine (GalN)-induced Wistar rat model of fulminant hepatic failure (FHF). The results of sequential observations in 10 FHF rats showed that the plasma GABA concentration doubled 24 hours after GalN injection, while there was no obvious clinical evidence of hepatic encephalopathy (HE). In overt HE 48 hours after the administration of GalN, the plasma concentration of GABA reached the peak value of 9,744 +/- 1,661 pmol/ml, which was 12 times as high as that before GalN injection. The consciousness, plasma concentration of GABA and SGPT activity became normal 120 hours after GalN injection. It is suggested that determination of plasma concentration of GABA is of value in the diagnosis of HE.

The use of proteolysis and direct N-terminal sequence analysis to study human interleukin-2/receptor interaction on solid support

An immobilized interleukin-2 receptor which is capable of binding interleukin-2 and suitable for direct N-terminal sequence analysis was employed to study interleukin-2/receptor interactions. Sensitive tryptic sites on the immobilized receptor and its interleukin-2 complex were identified by sequence analyses and compared. The results have revealed that the N-terminal region of interleukin-2 is not involved in receptor binding and the peptide segment covering residues 36-39 in the receptor is probably near or involved in the interleukin-2 binding site. The rapidity and simplicity make this solid phase sequence approach a good method for analyzing interleukin-2/receptor interaction and may be suitable for studying other protein-ligand interactions.

Epstein-Barr virus nuclear protein 2 is a key determinant of lymphocyte transformation

Epstein-Barr virus (EBV) efficiently transforms B lymphocytes to perpetual proliferation. The EBV laboratory strain P3HR-1 is transformation-incompetent and lacks a DNA segment that includes the EBV nuclear antigen 2 (EBNA-2) gene and a portion of the EBNA leader protein (EBNA-LP) gene. These two genes are expressed in transformed B lymphocytes. Recombinant transformation-competent EBVs were produced by transfecting P3HR-1-infected cells with a cosmid containing the DNA deleted in P3HR-1. Deletion of 105 nucleotides from the middle of the EBNA-2 gene had no discernible affect on transformation. Two larger EBNA-2 deletions abolished transformation but did not affect EBNA-2 nuclear localization. Two naturally occurring EBV variants (EBV types 1 and 2) differ extensively in their growth-transformation phenotype and in their EBNA-LP, EBNA-2, and EBNA-3A, -3B, and -3C genes. Recombinant P3HR-1 carrying EBV-1 EBNA-2 has many of the EBV-1 in vitro growth-transforming effects; recombinant P3HR-1, isogenic except for EBV-2 EBNA-2, has many of the EBV-2 growth-transforming effects including slow emergence of transformants, growth in tight clumps with few surrounding viable cells, and early sensitivity to dilution with fresh medium. Thus, EBNA-2 is an essential molecule in lymphocyte growth transformation by EBV and a major determinant of the differences between EBV-1 and EBV-2 in lymphocyte growth transformation.

Active opioid binding protein from rat brain--a glycoprotein containing alpha-methyl-D-mannoside residues

Active opioid binding protein was partially purified from rat brain by Vicia bungei Ohwi lectin (VBL). Mannose also existed in opioid receptors since the binding between opioid binding protein and VBL is specific, via alpha-methyl-D-mannoside (MeMan) residues. Since the active opioid binding protein purified by VBL chromatography was enriched about 200-folds. VBL can be used as effective purification tool which is much better than wheat germ agglutinin (WGA), a lectin commonly used in purifying opioid receptor.

Detection of antiphospholipid autoantibody in systemic lupus erythematosus is temperature-dependent

Non-reactive SLE sera in an ELISA for anticardiolipin antibody (aCL) retested positive in the immunoassay when the sera were first heat-inactivated at 56 degrees C for 30 minutes. This was not a false positive phenomenon since the positive ELISA reactivity of the heated SLE sera was markedly reduced by inhibition with the cardiolipin antigen. Furthermore, the heat-potentiated ELISA reaction was abolished by prior IgG depletion of the SLE sera with Protein A preparation. The unmasked aCL in the heat-treated SLE sera also exhibited selective binding in ELISA to other negatively-charged phospholipids, namely phosphatidylserine and phosphatidic acid but not against either phosphatidylcholine or phosphatidyl-ethanolamine. The data strongly indicate an interaction between antiphospholipid antibodies and heat-sensitive serum component(s), a reduction of the latter resulting in the ELISA detection of the autoantibody.

Epstein-Barr virus latent infection membrane protein increases vimentin expression in human B-cell lines

Latent Epstein-Barr virus (EBV) infection activates B-lymphocyte proliferation through mechanisms which are partially known. One approach to further delineate these mechanisms is to identify cellular genes whose expression is augmented in cells latently infected with EBV. Since EBV-negative Burkitt's lymphoma cells can be grown in continuous culture and EBV can establish growth-altering latent infection in these cells, some effects of EBV on B-lymphocyte gene expression can be studied by using this in vitro system. Pursuing this latter approach, we have used cDNA cloning and subtractive hybridization to identify a gene whose expression is increased after EBV infection. This gene encodes the cytoskeletal protein vimentin. Latent infection of established EBV-negative Burkitt's lymphoma cell lines with the transforming EBV strain, B95-8, resulted in dramatic increases in vimentin mRNA and protein levels, while infection with the nontransforming P3HR1 strain failed to do so. Vimentin induction was reproduced by the expression of the single EBV gene which encodes the latent infection membrane protein (LMP). An amino-terminal LMP deletion mutant did not induce vimentin. These results are of particular interest in light of the transforming potential of LMP, as demonstrated in rodent fibroblasts, and the interaction between vimentin and LMP observed in immunofluorescent colocalization and cell fractionation studies.

[Efficacy of ofloxacin in treating typhoid fever]

We studied 75 patients (36 males and 39 females), suffering from typhoid fever. 64 patients were treated with ofloxacin and 11 with amikacin, dosage regimens of the two drugs were 300 mg and 300-400 mg twice daily. Clinical effective rate was 100% with ofloxacin and 36.4% with amikacin. A total of 72 strains of salmonella typhi was isolated from all the patients of both groups. Bacteriological elimination rate was 100% with ofloxacin after treatment. Sensitive rates for S. Typhi isolated was 100% with ofloxacin, norfloxacin and ceftriaxone, 98.6% with amikacin and 20-21.4% with chloramphenicol, ampicillin and sulfamethoxazole Co. There were fewer adverse reactions and better acceptance, one had skin rash and one had gastrointestinal disturbance. In amikacin group, abnormality of urine routine and serum creatinine was observed. Ofloxacin was well absorbed orally. Its high bioavailability, satisfactory therapeutic efficacy excellent tolerability and convenience for use make it a very useful medication in the therapy of typhoid fever resulted from multiresistant strains.

Methicillin-resistant Staphylococcus aureus from China characterized by digestion of total DNA with restriction enzymes

A series of clinical isolates of methicillin resistant Staphylococcus aureus (MRSA) from two hospitals in China was examined. Fragment patterns obtained by digestion of total cellular DNA with restriction enzymes were used to characterize the isolates, in combination with phage-typing, antibiotic resistance profile, and plasmid profile. Digestion of total cellular DNA with restriction enzymes was most useful in discriminating between isolates and yielded additional information on the relatedness of non-identical isolates. In one hospital a single strain, resistant to a large number of antibiotics, had apparently become endemic. In the second hospital a number of distinct but related strains were present. The isolates were also related but not identical to the strain of MRSA endemic at the London Hospital.

Tetraphenylborate potentiates the respiratory inhibition by the dopaminergic neurotoxin MPP+ in both electron transport particles and intact mitochondria

The cytotoxicity of 1-methyl-4-phenylpyridinium (MPP+) is believed to arise as a consequence of its time- and energy-dependent accumulation inside mitochondria, followed by inhibition of electron transport at Complex I of the respiratory chain. Consistent with our proposal that the accumulation of MPP+ represents a passive Nernstian transport into mitochondria in response to the transmembrane electrochemical potential gradient, tetraphenylborate (TPB-) was found to accelerate the onset of the respiratory inhibition by MPP+ on intact mitochondria. Moreover, the ultimate level of inhibition reached was unexpectedly also increased. The latter is now explained by our finding that TPB- elicits a 12-fold enhancement of MPP+ inhibition of respiration in electron transport particles. It is suggested that TPB- facilitates access of MPP+ to its intramembrane site of inhibitory action in Complex I.

Increased sarcolemmal membrane permeability of cardiac muscle cells in rats fed grains cultivated in a Keshan disease endemic area: a study with horseradish peroxidase as a tracer

The alteration of sarcolemmal membrane permeability of cardiac muscle cells in rats fed grain from a Keshan disease (KD) endemic area was studied with horseradish peroxidase (HRP) as a tracer. Weanling male rats were divided at random into three groups and fed the following three diets, respectively, for 3 months: a diet with grain from a KD endemic area (Group A), a diet with grain from a KD nonendemic area (Group B), and standard laboratory chow (Group C). At the end of the experiment, HRP was injected intravenously and localized in the ventricular myocardium by light microscopy. The experimental results showed that the percentage of cardiac muscle cells containing HRP reaction product in rats fed grain from the KD endemic area was significantly greater than that in rats fed grain from nonendemic area and standard laboratory chow. This suggests that the sarcolemmal membrane permeability of cardiac muscle cells in rats of Group A was markedly increased. The distribution of cardiac muscle cells with increased sarcolemmal membrane permeability was similar to that seen in the myocardium of KD patients. The present study suggests that the abnormal membrane permeability of cardiac muscle cells may play an important role in the pathogenesis of myocardial necrosis in KD.

Treatment of typhoid fever with ofloxacin

Ofloxacin, 300 mg 12-hourly, was given orally to 64 patients with typhoid fever, all with positive blood cultures. Almost 80% of the isolates were resistant to chloramphenicol, ampicillin and co-trimoxazole, but sensitive to ofloxacin and norfloxacin. Fever subsided within five days in most patients (mean 3.2 +/- 1.1), rates of clinical effectiveness and bacteriological cure both being 100%. Thirty patients were followed for 1-3 months after the completion of therapy with no occurrence of relapse.

Steroid induced exophthalmos. A case report

A case of steroid induced exophthalmos in a patient with systemic lupus erythematosus with renal involvement is described. Computed Tomography was used to demonstrate the increased retro-orbital fat.

Fracture behavior of urinary stones under compression

The fracture behavior of two types of urinary stones, namely struvite and calcium oxalate, during compression testing was studied. Scanning electron microscopy (SEM) was used to characterize the fracture surfaces. Both types of stone showed pseudo-plastic behavior as indicated by their load-displacement curve. The onset of nonlinear behavior was found to correspond to development of microcracks in the specimens. The compressive strength was defined as the stress calculated at the maximum load. In struvite samples, the maximum load corresponded with the development of large cracks parallel to the compressive axis. For oxalate stones a separation of the outer layer (crust) from the inner layer (core) marked the point of maximum load. The compressive strength of the struvite samples was found to depend on the orientation of lamellae relative to the loading axis. Struvite stones, when loaded parallel to the lamination direction showed a higher compressive strength than oxalate stones did. The fracture behavior and compressive strength of a model material (z-brick) were also characterized and compared to those of the urinary stones.

Renal size in healthy Malaysian adults by ultrasonography

Two hundred and five healthy Malaysian adults were scanned for the length of their kidneys and the cortical thickness by both the sector real time and linear array static B-scan diagnostic ultrasound. The length of the left kidney was found to measure 105 (98-111) mm for males, and 100 (94-106) mm for females on average from the sector scan and the static B-scan. The right renal length was 102 (96-119) mm for males, and 98 (92-103) mm for females on the average from readings of both scans. The left kidney is longer in length than the right kidney in males and females on both scans. The cortical thickness at the equator of the kidneys of males and females ranges from 12-14 mm. In both sexes, the lengths of the kidneys may be estimated by the distance between the first to the fourth lumbar transverse processes when there is no scoliosis.

pH dependence of actin self-assembly

Fluorescence enhancement and fluorescence photobleaching recovery have been utilized to examine actin self-assembly over the pH range 6.6-8.0. The kinetics of assembly are faster and the critical concentrations are lower at lower pH. Filament diffusion coefficients are not a function of pH, indicating that average filament lengths are not pH dependent. Although critical actin concentrations are a sensitive function of the concentrations of various cations in the medium, the relative pH dependences of critical concentrations are similar for all combinations of cations employed. The pH dependence of actin self-assembly is sufficiently great that it should be taken into account when comparing data from different reports and when relating in vitro measurements to cytoplasmic mechanisms.

Cerebrospinal fluid pseudocyst presenting as a hepatic mass: a complication of ventriculoperitoneal shunt

The case of a 3-year-old male child is reported who had a history of congenital hydrocephalus, treated by VP shunting. Severe complications with VP shunting are rare, but in this case the shunt had apparently perforated the liver, causing a pseudocyst to form and subsequent hepatomegaly. The shunt was revised surgically and the pseudocyst resected.

Epstein-Barr virus latent infection membrane protein alters the human B-lymphocyte phenotype: deletion of the amino terminus abolishes activity

A latent infection membrane protein (LMP) encoded by the Epstein-Barr virus (EBV) genome in latently infected, growth-transformed lymphocytes alters the phenotype of a human EBV-negative B-lymphoma cell line (Louckes) when introduced by gene transfer. These LMP-expressing cells exhibit increased homotypic adhesion due to increased expression of the adhesion molecules LFA-1 and ICAM-1. Increased homotypic adhesion could foster B-cell growth by facilitating autocrine growth factor effects. LFA-3 expression is also induced. The induction of LFA-3 and ICAM-1 results in increased heterotypic adhesion to T lymphocytes. This could result in more effective T-cell immune surveillance. Since LMP is expressed in EBV-transformed lymphocytes and has been demonstrated to transform rodent fibroblasts in vitro, a wide range of possible effects on B-lymphoma cell growth were assayed. In the Louckes B-lymphoma cell line, EBV LMP causes increased cell size, acid production, plasma membrane ruffling, and villous projections. Although cell proliferation rate was not greatly affected, the steady-state intracellular free calcium level, transforming growth factor beta responsiveness, and expression of the lymphocyte activation markers (CD23 and transferrin receptor) were increased. Thus, LMP appears to be a mediator of EBV effects on B-cell transformation. In transfected lymphoma cells, LMP localizes to patches at the cell periphery and associates with the cytoskeleton as it does in EBV-transformed B lymphocytes or in rodent fibroblasts. A partially deleted form of LMP (D1LMP) does not aggregate in patches or associate with the cytoskeleton and had little effect on B-cell growth. Thus, cytoskeletal association may be integral to LMP activity.

Analysis of rhodamine and fluorescein-labeled F-actin diffusion in vitro by fluorescence photobleaching recovery

Properties of filamentous acetamidofluorescein-labeled actin and acetamidotetramethylrhodamine-labeled actin (AF and ATR-actin, respectively) were examined to resolve discrepancies in the reported translational diffusion coefficients of F-actin measured in vitro by FPR and other techniques. Using falling-ball viscometry and two independent versions of fluorescence photobleaching recovery (FPR), the present data indicate that several factors are responsible for these discrepancies. Gel filtration chromatography profoundly affects the viscosity of actin solutions and filament diffusion coefficients. ATR-actin and, to a lesser degree, AF-actin show a reduction in viscosity in proportion to the fraction labeled, presumably due to filament shortening. Actin filaments containing AF-actin or ATR-actin are susceptible to photoinduced damage, including a covalent cross-linking of actin protomers within filaments and an apparent cleavage of filaments detected by a decrease of the measured viscosity and an increase in the measured filament diffusion coefficients. Quantum yields of the two photoinduced effects are quite different. Multiple cross-links are produced relative to each photobleaching event, whereas less than 1% filament cleavage occurs. Substantial differences in the filament diffusion coefficients measured by FPR are also the result of differences in illumination geometry and sampling time. However, under controlled conditions, FPR can be used as a quantitative tool for measuring the hydrodynamic properties of actin filaments. Incremented filament shortening caused by photoinduced cleavage or incremental addition of filament capping proteins produces a continuous and approximately linear increase of filament diffusion coefficients, indicating that filaments are not associated in solution. Our results indicate that actin filaments exhibit low mobilities and it is inferred that actin filaments formed in vitro by column-purified actin, under standard conditions, are much longer than has conventionally been presumed.

Epstein-Barr virus-specific cytotoxic T-cell recognition of transfectants expressing the virus-coded latent membrane protein LMP

Cytotoxic T cells from Epstein-Barr virus (EBV)-immune individuals specifically kill EBV-transformed B cells from HLA class I antigen-matched donors even though the latently infected cells express only a restricted set of virus genes. The virus-induced target antigens recognized by these immune T cells have not been identified. In our experiments, EBV DNA sequences encoding the virus latent gene products Epstein-Barr nuclear antigen (EBNA)1, EBNA 2, and EBNA-LP and the latent membrane protein (LMP) were individually expressed in a virus-negative human B-lymphoma cell line, Louckes. Transfected clones expressing LMP were killed by EBV-specific cytotoxic T-cell preparations from each of three virus-immune donors HLA matched with Louckes through HLA-A2, B44 antigens; control transfectants or clones expressing one of the EBNA proteins were not recognized. Expression of LMP in a second virus-negative B-cell line, BL41, sensitized these cells to EBV-specific cytolysis restricted through the HLA-A11 antigen. To distinguish between the viral protein and an induced human B-cell activation antigen as the target for T-cell recognition, LMP was then expressed in a murine mastocytoma cell line, P815-A11-restricted human T cells. The LMP-expressing P815-A11 transfectants were susceptible to lysis by EBV-specific cytotoxic T cells from three HLA-A11-positive individuals. Both Louckes and P815-A11 cells were also transfected with constructs capable of encoding a truncated form of LMP (Tr-LMP) which lacks the N-terminal 128 amino acids of the full-length protein. Tr-LMP-expressing transfectants were not recognized by the above T-cell preparations. The results suggest that LMP, and, in particular, epitopes derived from the N-terminal region of the protein, provides one of the target antigens for the EBV-induced human cytotoxic T-cell response.

Roentgenocephalometric study of complete unilateral cleft lip and palate patients treated with delayed closure of the hard palate--a preliminary report

Cephalometric radiographs of a sample of complete unilateral cleft lip and palate patients (15 males, 15 females, aged 6.5 to 7.5 years) were analysed. In most cases, an adhesion cheiloplasty was done at 3 months of age, followed by definitive cheiloplasty at 6 to 12 months, then by posterior palatoplasty at 1.5 years. The hard palate was not repaired till the age of 5-7 years. This preliminary study indicated that: (1) The growth of maxilla and mandible shows no sex difference, except the anteroposterior maxillary length, which is longer in the cleft males. (2) The maxilla of our group is more retruded than that of normal noncleft children. (3) The mandibular growth is essentially normal except the higher mandibular plane in the cleft females. (4) The intermaxillary relation and skeletal profile of the cleft males are more favourable than in the early closure group.

A fifth Epstein-Barr virus nuclear protein (EBNA3C) is expressed in latently infected growth-transformed lymphocytes

Three distantly homologous neighboring long open reading frames in the Epstein-Barr virus (EBV) genome are preceded by short open reading frames. The leftmost short and long open reading frames encode EBNA3, a nuclear protein which is slightly smaller (145 kilodaltons [kDa]) than two other nuclear proteins (150 to 155 kDa) detected in Western blots (immunoblots) of latently infected cell protein (K. Hennessy, F. Wang, E. Woodland-Bushman, and E. Kieff, Proc. Natl. Acad. Sci. USA 83:5693-5697, 1986; I. Joab, D. T. Rowe, M. Bodescot, J.-C. Nicolas, P. J. Farrell, and M. Perricaudet, J. Virol. 61:3340-3344, 1987). We have demonstrated that the most rightward short (BERF3) and long (BERF4) open reading frames are spliced in frame at the 3' end of a 5-kilobase latently infected cell RNA and that this RNA begins within or upstream of the EBV long internal repeat. EBV-immune human antibodies specific for the long open reading frame translation product identified a 155-kDa protein on Western blots of latently infected cell protein and specifically reacted with large nonnucleolar nuclear granules in every latently infected cell. Expression of the cDNA in BALB/c 3T3 cells resulted in translation of full-size EBNA3C but had no effect on cell morphology, contact inhibition, or serum independence.

Development of articulation before delayed hard-palate closure in children with cleft palate: a cross-sectional study

The development of articulation before surgical closure of the hard palate was compared in 75 preschool children with cleft lip and palate and 40 preschool children born without clefts. The children were aged 2 years to 5 years 11 months. The patients had significantly poorer articulation skills than the controls at each age level. Substitutions were the most frequent error, and they did not decrease with age in the patients. Fistula size and a history of speech therapy were significant factors in the articulation error scores only in 5-year-olds. No advantage in articulation proficiency was found for those who had worn a prosthesis to occlude the hard-palate defect.

Extensive scalds following accidental immersion in hot water pools

The scalds produced by immersion in hot water pools were extensive, usually of superficial depth on the upper parts of the body and deep dermal or full thickness skin loss on the lower parts. Blisters appeared rather slowly, within 2 days post-burn and often dispersed spontaneously. The estimated burned area on admission may thus be smaller than found subsequently. This study showed that the volume of fluid required for adequate resuscitation during the first post-burn day may be only 1.5 ml/kg/% BSA burned. Deep dermal burns were treated preferably by early tangential excision and grafting. The full thickness skin loss was treated by escharectomy and skin grafts.

Epstein-Barr virus nuclear antigen 2 specifically induces expression of the B-cell activation antigen CD23

Epstein-Barr virus (EBV) infection of EBV-negative Burkitt lymphoma (BL) cells induces some changes similar to those seen in normal B lymphocytes that have been growth transformed by EBV. The role of individual EBV genes in this process was evaluated by introducing each of the viral genes that are normally expressed in EBV growth-transformed and latently infected lymphoblasts into an EBV-negative BL cell line, using recombinant retrovirus-mediated transfer. Clones of cells were derived that stably express the EBV nuclear antigen 1 (EBNA-1), EBNA-2, EBNA-3, EBNA-leader protein, or EBV latent membrane protein (LMP). These were compared with control clones infected with the retrovirus vector. All 10 clones converted to EBNA-2 expression differed from control clones or clones expressing other EBV proteins by growth in tight clumps and by markedly increased expression of one particular surface marker of B-cell activation, CD23. Other activation antigens were unaffected by EBNA-2 expression, as were markers already expressed on the parent BL cell line, including BL markers (cALLA and BLA), proliferation markers (transferrin receptor and BK19.9), and cell adhesion-related molecules (LFA-1 and LFA-3). Increased CD23 expression in cells expressing EBNA-2 was apparent from monoclonal anti-CD23 antibody binding to the cell surface, from immunoprecipitation of the 45-kDa and 90-kDa CD23 proteins with monoclonal antibody, and from RNA blots probed with labeled CD23 DNA. The results indicate that EBNA-2 is a specific direct or indirect trans-activator of CD23. This establishes a link between an EBV gene and cell gene expression. Since CD23 has been implicated in the transduction of B-cell growth signals, its specific induction by EBNA-2 could be important in EBV induction of B-lymphocyte transformation.

A bicistronic Epstein-Barr virus mRNA encodes two nuclear proteins in latently infected, growth-transformed lymphocytes

EBNA2 is a nuclear protein expressed in all cells latently infected with and growth transformed by Epstein-Barr virus (EBV) infection (K. Hennessy and E. Kieff, Science 227:1230-1240, 1985). The nucleotide sequence of the EBNA2 mRNA (J. Sample, M. Hummel, D. Braun, M. Birkenbach, and E. Kieff, Proc. Natl. Acad. Sci. USA 83:5096-5100, 1986) revealed that it begins with a 924-base open reading frame that has an unusual potential translational initiation site (CAAATGG). This open reading frame is followed by 138 nucleotides with only one highly unlikely translational initiation site (TACATGC), which would translate a pentapeptide before the next stop codon. The last part of the mRNA is the open reading frame which encodes EBNA2. In this paper, we demonstrate that the 924-base open reading frame translates a 40-kilodalton protein in vitro or in murine cells transfected with the EBNA2 cDNA under control of the murine leukemia virus long terminal repeat. A protein of identical size was detected in EBV-transformed, latently infected human lymphocyte nuclei by using antibody specific for the leader open reading frame expressed in bacteria. Therefore, this is a rare example of a mRNA which translates two proteins from nonoverlapping open reading frames. Since the protein encoded by the leader of the EBNA mRNA is expressed in all nuclei of a latently infected cell line, it was designated EBNA-LP. EBNA-LP localizes to small intranuclear particles and differs in this respect from EBNA1, EBNA2, or EBNA3. EBNA-LP is not expressed in an EBV-transformed marmoset lymphocyte cell (B95-8) or in one EBV-infected Burkitt tumor cell line (Raji) but is expressed in three other Burkitt tumor cell lines (Namalwa, P3HR-1, and Daudi).

Suppressor T cell clones from patients with acute Epstein-Barr virus-induced infectious mononucleosis

Suppression and/or cytotoxicity are believed to play an important role in the defense against Epstein-Barr virus (EBV) infection. To analyze the role of suppressor T cells in relation to EBV, we sought to clone and study these T cells. Analysis of 152 T cell clones derived from the peripheral blood of two patients with acute EBV-induced infectious mononucleosis (IM) yielded 11 highly suppressive clones that had no cytotoxic activity for the natural killer sensitive K562 cell line, an autologous EBV-infected cell line, or an allogeneic EBV-infected B cell line. Four of six suppressor T cell clones also profoundly inhibited EBV-induced immunoglobulin production, and five of five clones delayed the outgrowth of immortalized cells. These results indicate that during acute IM, suppressor T cells capable of inhibiting B cell activation in the absence of cytotoxicity can be identified, and may play a key role in the control of EBV infection.