Phosphorylation of the duck hepatitis B virus capsid protein associated with conformational changes in the C terminus

The capsid protein of duck hepatitis B virus (DHBV) is phosphorylated at multiple sites during viral infection. A cluster of sites is located near the C terminus of the 262-amino-acid protein. We have used site-directed mutagenesis to show that three serines and one threonine serve as phosphate acceptor amino acids in the C terminus. An additional six potential phosphate acceptor sites in this region were apparently not utilized. Each serine or threonine that served as a phosphate acceptor was adjacent to a downstream proline, while all six serines that were not acceptors for phosphate residues lacked adjacent downstream prolines. Mutation of the downstream proline to glycine at each site had the same effect as mutating the serine itself, suggesting an SP or TP motif as an essential feature for capsid protein phosphorylation. Phosphorylation at these four sites resulted in complex shifts in electrophoretic mobility in sodium dodecyl sulfate gels of the capsid protein or of a C-terminal peptide containing the phosphorylated sites, suggesting that specific conformations of the C terminus are associated with different combinations of phosphorylated serines. We speculate that distinct functions of the C terminus may be associated with different phosphorylated domains on the intact capsid.

Augmented interferon-gamma, interleukin-4 and transforming growth factor-beta mRNA expression in blood mononuclear cells in myasthenia gravis

The abnormal T lymphocyte-dependent production of antibodies to the nicotinic acetylcholine receptor (AChR) in myasthenia gravis (MG) suggests a role for immunoregulatory cytokines. We examined the T helper type 1 (Th1) cell-associated interferon-gamma (IFN-gamma) that promotes cell-mediated immunity, the Th2 cell-related interleukin-4 (IL-4) that augments B cell immunity, and transforming growth factor-beta (TGF-beta) that downregulates immune responses but enhances isotype switching. Blood mononuclear cells (MNC) expressing cytokine mRNA were enumerated after in situ hybridization with labelled complementary DNA oligonucleotide probes for IFN-gamma, IL-4 and TGF-beta. MG patients had elevated numbers of cells expressing IFN-gamma and IL-4 compared to patients with non-inflammatory neurological diseases and healthy controls, implying that both Th1- and Th2-like cells are involved in MG. TGF-beta-positive cells were also elevated in MG. The levels of cytokine-positive MNC were similar in MG and in control patients with other inflammatory neurological diseases. There were no associations between numbers of cytokine-positive blood MNC and clinical variables of MG, but individual patients need to be studied over the course of MG to clarify a relation between the cytokines under study and clinical or laboratory variables of MG.

A negative regulatory element upstream from the mouse Adh-1 gene can down-regulate a heterologous promoter

Regulation of Adh-1 (encoding mouse alcohol dehydrogenase-A2) gene expression results from the interplay of positive and negative effects. We report here the detection and localization of a negative regulatory element (NRE) to the sequence between -754 and -732 bp relative to the transcription start point (tsp). This element, which we call Adh-1 NRE2, can down-regulate transcription from a strong heterologous promoter (the SV40 promoter+enhancer). Adh-1 NRE2 can function in both orientations and either upstream or downstream from the promoter, and thus has attributes characteristic of a 'silencer'. A protein that binds to the Adh-1 NRE is widespread in mouse tissues.

[The effect of interleukin-2, interleukin-4 and tumor necrosis factor on LAK cells activity]

We studied the effect of single or combination of interleukin-2 (IL-2), interleukin-4 (IL-4) and tumor necrosis factor (TNF) on lymphokine-activated killer cells (LAK) activity which killed both of target cells HepG2 and 2 2,1,5 cells induced for seven days. It was shown that LAK activity induced by the combination of triplet of IL-2, IL-4 and TNF was higher than that induced by single or two of IL-2, IL-4 and TNF, and that enhanced LAK activity was associated with the quantity of IL-2 receptor expression and lysosomes of LAK precursors.

Stature estimated from knee height in elderly Japanese Americans

OBJECTIVE

To validate the use of knee-height-to-stature formulas established on Caucasian subjects to estimate height of Japanese-Americans, ages 60 to 90 years.

DESIGN

Survey by measurement of a convenience sample.

SUBJECTS

Japanese-American men and women patients, aged 60 years or older, at The Queen's Medical Center during March and April 1992.

MEASUREMENTS

Each subject's height (without shoes) was measured in inches by standard height scale and then converted to centimeters. Each subject's knee height was measured using the tool and procedure described by Chumlea et al (Journal of the American Geriatrics Society 1985; 33:116-120).

RESULTS

Statures of Japanese-American men and women predicted by the regression models developed on the Hawaii sample were significantly different (P < 0.0001) from the heights predicted by the Caucasian regression model developed by Chumlea and associates (1985).

CONCLUSIONS

The statistical models specific to elderly Japanese Americans predicted more precise height approximation than models developed on Caucasians.

Serine protease inhibitors block N-terminal arginylation of proteins by inhibiting the arginylation of tRNA in rat brains

The tRNA mediated, posttranslational, N-terminal arginylation of proteins occurs in all eukaryotic cells. In nervous tissue, these reactions can be inhibited by endogenous molecules with a molecular weight of between one thousand and five thousand. In the present experiments, exogenous serine protease inhibitors (10(-5) M or less) but not other types of protease inhibitors, were found to be able to block the arginylation of protein in extracts of rat brain homogenates. Inhibition was not by the usual mode of action of protease inhibitors, but by interfering (non-competitively) with the charging of tRNA. Since arginylated proteins are rapidly ubiquitinated and degraded by cytosolic proteases, serine protease inhibitors may act to stabilize proteins by a dual mechanism of inhibiting arginylation as well as inhibiting serine proteases.

The impact of harvest center on quality of marrows collected from unrelated donors

The total number and distribution of nucleated cells in harvested bone marrow are potentially important determinants of patient outcome following bone marrow transplantation. In order to assess whether marrows collected from predominantly unrelated donors at Georgetown University Medical Center (GUMC) were different in cellular content from marrows collected at harvest centers outside of GUMC, we compared the nucleated cell counts and mononuclear cell subset distribution (CD34, CD3, CD4, CD8, CD19 antigen-positive cell content) of 10 consecutive marrows harvested at GUMC to 10 unrelated donor marrows from outside harvest centers. Significantly higher nucleated cell counts and CD34 antigen-positive cell content and significantly lower CD3 and CD4 antigen-positive T-cell numbers were demonstrated among the marrows harvested at GUMC. These results confirmed significant variability in marrow collection practices between GUMC and 10 different outside harvest centers and suggest that strict adherence to a specific collection procedure, involving small volume marrow aspirations and multiple puncture sites, results in a product with a high number of early hematopoietic progenitor cells and minimal contamination by peripheral blood. These data further suggest the need for careful monitoring of individual unrelated donor marrow collection centers' practices to optimize the quality of the harvested marrow.

Collagen induced MMP-2 activation in human breast cancer

Matrix metalloproteinase-2 (MMP-2), a zymogen requiring proteolytic activation for catalytic activity, has been implicated broadly in the invasion and metastasis of many cancer model systems, including human breast cancer (HBC). MMP-2 has been immunolocalized to carcinomatous human breast, where the degree of activation of MMP-2 correlates well with tumor grade and patient prognosis. Using Matrigel assays, we have stratified HBC cell lines for invasiveness in vitro, and compared this to their potential for metastatic spread in nude mice. HBC cell lines expressing the mesenchymal marker protein vimentin were found to be highly invasive in vitro, and tended to form metastases in nude mice. We have further discovered that culture on collagen-I gels (Vitrogen; Vg) induces MMP-2-activator in highly invasive but not poorly invasive HBC cell lines. As seen for other MMP-2-activator inducing regimens, this induction requires protein synthesis and an intact MMP-2 hemopexin-like domain, appears to be mediated by a cell surface activity, and can be inhibited by metalloproteinase inhibitors. The induction is highly specific to collagen I, and is not seen with thin coatings of collagen I, collagen IV, laminin, or fibronectin, or with 3-dimensional gels of laminin, Matrigel, or gelatin. This review focuses on collagen I and MMP-2, their localization and source in HBC, and their relationship(s) to MMP-2 activation and HBC metastasis. The relevance of collagen I in activation of MMP-2 in vivo is discussed in terms of stromal cell: tumor cell interaction for collagen I deposition, MMP-2 production, and MMP-2-activation. Such cooperativity may exist in vivo for MMP-2 participation in HBC dissemination. A more complete understanding of the regulation of MMP-2-activator by type I collagen may provide new avenues for improved diagnosis and prognosis of human breast cancer.

Intracellular immunization of human T cells with a hairpin ribozyme against human immunodeficiency virus type 1

T-cell lines (Jurkat and Molt-4) were transduced with retroviral vectors containing a hairpin ribozyme that targets a conserved sequence in the 5' transcribed leader sequence of human immunodeficiency virus (HIV) type 1. Stable cell lines were generated which constitutively and persistently expressed the ribozyme gene driven by either the Moloney retroviral long terminal repeat (LTR) or an internal human tRNA(val) promoter. There was no apparent deleterious effect of long-term ribozyme expression on cell proliferation or viability. Cells expressing ribozyme were resistant to challenge from diverse strains of HIV, including an uncloned clinical isolate. No reverse transcriptase activity or virus infectivity was detectable in the culture supernatants of Jurkat cells expressing the ribozyme driven by the tRNA(val) promoter up to 35 days after challenge with HIV-1/HXB2. Expression of the ribozyme also significantly decreased (by approximately 50- to 100-fold) the efficiency of incoming virus to synthesize viral DNA. These and previously reported results indicate that transfer and expression of the ribozyme gene interfere with both early and late events in the HIV replication cycle and confer long-term resistance to HIV-1 infection.

Progress towards gene therapy for HIV infection

The retroviral life cycle and genetic plasticity of human immunodeficiency virus 1 (HIV-1) present unprecedented therapeutic challenges. Twelve years into the HIV epidemic, satisfactory treatment remains elusive. Our current understanding of AIDS pathogenesis calls for early intervention with antiviral agents. Although still in its infancy, human gene therapy holds considerable potential for the long-term treatment of genetic disorders, cancer and chronic infectious diseases. Gene therapy for HIV infection is receiving particularly intensive study: approaches that are in development include both immunotherapy (e.g. therapeutic vaccines and adoptive transfer of CD8+ T-cell clones) and direct antiviral therapy (intracellular immunization). The latter strategies include transdominant modifications of HIV proteins, RNA decoys, antisense RNA, ribozymes and modifications of cellular proteins (e.g. intracellular antibodies, soluble CD4). Several of these strategies are now entering clinical trials. While significant conceptual and technical hurdles remain to be overcome before the promise of gene therapy for HIV infection can be fully realized, progress in this field is likely to be rapid and to contribute to the broader applicability of human gene therapy to the treatment of other disorders.

Inhibitory nerve distribution and mediation of NANC relaxation by nitric oxide in horse airways

The distribution of inhibitory nerves and the mediator of the inhibitory nonadrenergic noncholinergic (iN-ANC) nervous system were investigated in smooth muscle preparations from seven regions of equine airways. In tissues incubated with atropine and precontracted with histamine, electrical field stimulation produced frequency-dependent relaxation, and the magnitude of the relaxation decreased from trachea to central bronchi and was absent in peripheral airways. The degree of relaxation in bronchi was not simply a function of bronchial size or generation. Propranolol inhibited part of the relaxation only in the cranial trachealis. After propranolol, NG-nitro-L-arginine, a nitric oxide (NO) synthase inhibitor, eliminated the remaining relaxation in all preparations. This effect was reversed by L-arginine, the NO precursor, but not by D-arginine. Exogenous NO concentration dependently relaxed trachealis. These results indicate that: 1) adrenergic innervation is limited to cranial trachealis, 2) iNANC nerves supply the trachea and central bronchi, and 3) NO mediates iNANC function.

Allelic variation in the dihydrofolate reductase gene at amino acid position 95 contributes to antifolate resistance in Chinese hamster cells

The Chinese hamster lung cell line DC-3F contains two polymorphic dihydrofolate reductase (DHFR) alleles that are defined by an Asp-Asn amino acid sequence difference at position 95 in protein. Previously, we reported that the antifolate-resistant subline DC-3F/A3 overexpressed a Leu22-->Phe mutant of the Asp95 (21k) allele and that this was the basis of its resistance to methotrexate (MTX) and methasquin [P. W. Melera, J. P. Davide, C. A. Hession, and K. W. Scotto, Mol. Cell. Biol., 4: 38-48, 1984]. We now show that another independently selected antifolate-resistant subline of DC-3F, DC-3F8/A55, in addition to being severely compromised in its ability to accumulate MTX, overexpresses a Leu22-->Phe mutant form of the Asn95 (20k) allele. Characterization of purified DHFR from these cells showed that the enzyme displayed a 6-fold higher Kd for MTX (3.92 +/- 0.17 pM) than the wild type (0.58 +/- 0.10 pM), thus explaining its lowered sensitivity to drug. Unexpectedly, however, this value was 4-fold lower than that displayed by the DC-3F/A3 enzyme even though both contain the same (Leu22-->Phe) mutation and differ only at position 95. Indeed, we have also shown that the 21k and 20k wild type enzymes, both containing Leu at position 22, in fact differ by 3-fold (1.58 +/- 0.08 and 0.58 +/- 0.10 pM, respectively) in their Kd's for MTX. This demonstrates that the amino acid at position 95 has an effect on the ability of DHFR to bind MTX. On the other hand, these allelic variants are indistinguishable from each other in their catalytic properties and in their respective Kd's for dihydrofolate. Taken together, these characteristics are consistent with the observation that it is the wild type 21k allele which is preferentially overexpressed at a frequency of 3:1 in MTX-resistant Chinese hamster lung sublines derived by long-term selection in MTX. The results of these studies are novel in that they establish a role for allelic variation in the DHFR gene as a contributor to antifolate resistance in mammalian cells. Moreover, they implicate amino acid position 95 in the maintenance of the structure of the MTX binding pocket.

[IgG RF analysis of synovial fluid of the knee joints in 35 patients with rheumatic disease]

Rheumatoid arthritis (RA) is an autoimmune disease. IgG RF in the synovial fluid is a significant indicator for the pathogenesis and differential diagnosis of this disease. To now, RF tested by latex agglutination belongs to the IgM type whereas, in the rheumatoid synovial fluid, most of immunocomplex molecules are IgG which bind into a complex. IgG RF was determined by ELISA in the synovial fluid of 35 cases of joint disorders, including 12 cases of RA, 7 cases of reactive arthritis (ReA), 5 cases of osteoarthritis (OA) and 11 cases of non-synovitis (non-S) which were regarded as negative control. The upper limit of OD value +2s was 0.5. Using this standard 7 out of 12 cases of RA were positive. 2 of 5 cases of OA were weakly positive, and only one case of ReA was positive. This suggest that this test is valuable in the diagnosis of RA. We have also observed the relation between IgG RF in synovial fluid and X-ray and arthroscopic findings of the same knee joint. In 5 of 7 cases of positive RA, II-III X-ray changes and II-III cartilage destruction arthroscopic findings were noted, suggesting a relationship between IgG RF in synovial fluid and articular damage.

Prejunctional alpha 2-adrenoceptors inhibit acetylcholine release from cholinergic nerves in equine airways

To determine the presence and function of alpha 2-adrenoceptors on cholinergic nerves innervating horse airway smooth muscle, the effects of some alpha 2-adrenoceptor agents on contractions of and acetylcholine (ACh) release from equine airway smooth muscle preparations were studied. Muscle contractions were elicited by either electrical field stimulation (EFS) or exogenous ACh. ACh release was induced by EFS and measured by high-pressure liquid chromatography and electrochemical detection. The alpha 2-adrenoceptor agonists clonidine (10(-7) to 10(-5) M) and UK-14,304 (10(-8) to 10(-6) M) concentration dependently inhibited ACh release and the contractile response to EFS but not the response to exogenous ACh. This inhibition was attenuated by the alpha 2-adrenoceptor antagonists yohimbine and idazoxan but not by the alpha 1-adrenoceptor antagonist prazosin. These results indicate that alpha 2-adrenoceptors exist on cholinergic nerves innervating equine airway smooth muscle, and activation of these receptors inhibits cholinergic neurotransmission. The observation that yohimbine alone had little effect on the contractile response to EFS suggests that, under these experimental conditions, endogenous norepinephrine had no influence on tracheal cholinergic neurotransmission via prejunctional alpha 2-adrenoceptors.

Dependence of calmodulin localization in the retina on the NINAC unconventional myosin

Calmodulin is a highly conserved regulatory protein found in all eukaryotic organisms which mediates a variety of calcium ion-dependent signalling pathways. In the Drosophila retina, calmodulin was concentrated in the photoreceptor cell microvillar structure, the rhabdomere, and was found in lower amounts in the sub-rhabdomeral cytoplasm. This calmodulin localization was dependent on the NINAC (neither inactivation nor afterpotential C) unconventional myosins. Mutant flies lacking the rhabdomere-specific p174 NINAC protein did not concentrate calmodulin in the rhabdomere, whereas flies lacking the sub-rhabdomeral p132 isoform had no detectable cytoplasmic calmodulin. Furthermore, a defect in vision resulted when calmodulin was not concentrated in the rhabdomeres, suggesting a role for calmodulin in the regulation of fly phototransduction. A general function of unconventional myosins may be to control the subcellular distribution of calmodulin.

A double-blind, prospective, randomized trial of ketoconazole, a thromboxane synthetase inhibitor, in the prophylaxis of the adult respiratory distress syndrome

OBJECTIVE

To determine if ketoconazole, a thromboxane A2 synthetase inhibitor, given within the first 24 hrs after diagnosis and arrival in the intensive care unit (ICU) would decrease the frequency of adult respiratory distress syndrome in the septic patient population.

DESIGN

Prospective, randomized, double-blind, placebo-controlled study.

SETTING

Twelve-bed, surgical ICU in a university-affiliated hospital.

PATIENTS

Fifty-four consecutive patients admitted to the surgical ICU with the diagnosis of sepsis composed the study sample. Sepsis was defined as including two or more of the following signs in a patient with a systolic blood pressure of < 80 mm Hg or a systemic vascular resistance of < 800 dyne.sec/cm5: a) temperature > or = 39 degrees C or < or = 35 degrees C; b) white blood cell count of > 12,000 leukocytes, or < or = 4000 leukocytes/microL, or > or = 20% immature cells; c) positive blood culture; d) known or strongly suspected source of infection from which a known pathogen was cultured.

INTERVENTIONS

Patients were randomized to receive either ketoconazole (400 mg) or placebo in a double-blind fashion as early as possible and in < 24 hrs after surgical ICU admission or after the diagnosis of sepsis was established.

MEASUREMENTS AND MAIN RESULTS

Adult respiratory distress syndrome (ARDS) was diagnosed if the following criteria were met: a) intrapulmonary shunt of > 20%, or a PaO2/FIO2 ratio of < 150 requiring ventilatory support for > 48 hrs; b) pulmonary artery occlusion pressure of < 18 mm Hg and no clinical signs of heart failure; and c) diffuse infiltrates on chest radiograph. Treatment resulted in significant (p = .002) reduction in the frequency of ARDS compared with the placebo group, 64% vs. 15% in the ketoconazole treated group. The mortality rate was also reduced from 39% in the placebo group to 15% in the ketoconazole group (p = .05). A statistically significant reduction in ventilator and ICU days was not achieved.

CONCLUSIONS

Ketoconazole (400 mg through the gastrointestinal tract) given early in the septic course may prevent ARDS and decrease the mortality rate in high-risk, septic patients.

Presence of a specific antiestrogen binding site on human follicular thyroid carcinoma cell line (UCLA RO 82 W-1): inhibition by an endogenous ligand present in human serum

A receptor for antiestrogens, distinct from the estrogen receptor, has been identified in several tissues including the MCF-7 breast cancer cell line. Estrogen receptors have also been found in normal and pathological thyroid tissue homogenates. We demonstrate the presence of an antiestrogen binding site (AEBS) on a pure human follicular thyroid carcinoma cell line (UCLA RO 82 W-1) using a 3H-tamoxifen (3H-TAM) binding assay. The binding of 3H-TAM to the AEBS was determined after preincubation (30 min) of the cells with excess 17 beta-estradiol (2 mumol/L). Specific and saturable binding of 3H-TAM to the cells was observed. Displacement of the tracer from its binding site was dose dependent. Scatchard analysis revealed a dissociation constant (Kd) of 73 nmol/L, indicating a binding site with moderate affinity and capacity (72 pmol/10(6) cells). Using this assay we were also able to demonstrate the presence of an endogenous ligand for the AEBS in ethanol extracts of human serum. Cell growth and 3H-thymidine incorporation by the follicular thyroid carcinoma cells were inhibited when the cells were exposed to TAM (1.5 mumol/L). In conclusion, TAM is able to bind to a specific receptor on this follicular thyroid carcinoma cell line, and a natural circulating ligand present in ethanol extracts of human serum interferes with its binding.

In vitro and in vivo inhibition of nuclear type II estrogen binding sites in the dorsolateral prostate of noble rats

Competition analyses with a number of known bioflavonoids and related compounds revealed that three of them competed effectively for type II [3H]estradiol- 17 beta ([3H]E2) binding sites (type II sites) in the nuclei of rat dorsolateral prostate (DLP). Amongst the bioflavonoids tested, quercetin was the most effect, exhibiting approx. a 50% inhibition at 3000-fold molar excess concentration. In contrast, rutin and hesperitin were both not effective. Methyl p-hydroxyphenyllactate (MeHPLA), a suspected "endogenous" ligand for uterine type II sites [1; J. Biol. Chem. 263, 1988, 7203-7210], competed as well as estradiol-17 beta (E2) for prostatic type II sites (50% inhibition at 30-fold molar excess), whereas its demethylated product, HPLA, did not. 4,4'Dihydroxybenzylidene acetophenone, an esterase-stable MeHPLA analog, was also found to be a good competitor, exhibiting a 50% inhibition at 100-fold molar excess concentration. In a preliminary in vivo study, quercetin, administered either orally or subcutaneously, was found to be effective in preventing a joint testosterone (T) and E2 treatment-induced elevation of type II sites in rat DLP. Quercetin treatments also caused a small but significant reduction (17-18%) in DLP relative gland weights (gland wt/body wt) in T + E2-treated animals. Taken together, these data suggest that bioflavonoids and related compounds may influence prostatic function via interactions with prostatic type II sites.

Isolation of a peptide that inhibits the posttranslational arginylation of proteins in rat brain

All eukaryotic cells contain enzymes that are able to catalyze the transfer of Arg from tRNA to the N-terminus of naturally short lived or damaged cytosolic proteins. For certain test proteins, it has been shown that the addition of Arg to the N-terminus leads to their degradation via the ubiquitin proteolytic pathway. The mechanisms used by cells for identifying proteins for arginylation and regulating arginylation are not known. The present study reports the isolation of a peptide from rat brain that is able to inhibit the arginylation of proteins in brain extracts. We suggest that this peptide is the physiological regulator of arginylation in rat brain.

Independent modulation of horse airway smooth muscle by epithelium and prostanoids

The effects of epithelial removal and cyclooxygenase inhibition on contractions induced by exogenous acetylcholine (ACh) and electrical field stimulation (EFS) were evaluated in horse tracheal strips and bronchial rings. Epithelial removal potentiated the response to ACh but had no influence on the response to EFS. The effect of epithelial removal was not altered by pretreating the tissues with meclofenamate, a cyclooxygenase inhibitor. In trachealis strips, meclofenamate augmented contractions induced by EFS but not by ACh. In bronchial rings, meclofenamate augmented EFS-induced contraction to a greater extent than ACh-induced contraction. These effects of meclofenamate were epithelium-independent. We conclude that horse airway epithelium produces a relaxant factor that is not a prostanoid. Endogenous prostanoids originating from non-epithelial sites inhibit only cholinergic nerves in the trachea but both parasympathetic nerves and smooth muscle in the bronchi.