Interferon-induced expression of different genes is mediated by distinct regulatory pathways

Interferons (IFNs) regulate the expression of multiple genes and the regulatory sequences associated with several of these genes have been identified. How cell-surface IFN receptors communicate with such regulatory elements is as yet unknown. We have characterized the IFN responses of a mutant murine cell line (Ltk-aprt-) which is unable to mount an antiviral response when treated with IFN-beta. In contrast to its inability to activate antiviral pathways in these cells, IFN-beta inhibits their growth to the same level as observed in their parental L-929 line which is fully responsive to IFN, suggesting that distinct pathways account for antiviral and cytostatic responses. In agreement with this, Northern blot and nuclear run-on analyses show that the induction of transcription of three distinct genes (2,5(A) synthetase, BS-I-150, and BS-II-4) is blocked in Ltk-aprt- cells whereas another gene (I-8) is activated normally. Our results show that the defective responses observed in this cell line are not due to a nonfunctional IFN-beta cell-surface receptor and suggest that multiple pathways exist between the receptor and upstream gene regulatory elements.

Beta-blockers in portal hypertension. An overview

This paper describes a meta-analysis of data from the 5 primary and 15 secondary prevention studies in patients with portal hypertension, in which beta-blockers were compared with inactive control. These studies involved 1525 patients. Overall, the number of patients who suffered bleeding events was 38% lower in the groups treated with beta-blockers (p less than 0.001). The percentage reductions in bleeding-related deaths and in total mortality were 35% and 18%, respectively (p = 0.007 and p = 0.024). More detailed analysis supports the conclusion that propranolol, the beta-blocker predominantly used in these studies, is effective in both the primary and secondary prevention of bleeding events and mortality due to portal hypertension.

Treatment of an infected silicone right atrial catheter with combined fibrinolytic and antibiotic therapy: case report and review of the literature

Tunnelled silicone rubber right atrial catheters are commonly used to administer long-term total parenteral nutrition (TPN), cancer chemotherapeutic agents, and antimicrobial agents. The indwelling devices potentiate platelet-fibrin thrombi formation, providing a nidus for infection. Although many episodes of sepsis associated with thrombotic tunnelled catheters respond to antimicrobial therapy alone, a significant number require catheter removal. Evidence from case studies and small clinical trials suggests that fibrinolytic agents may increase the response rate and prevent removal of the device when combined with antimicrobial therapy. We present the first case reported of bacterial sepsis secondary to a thrombotic indwelling Hickman catheter for long-term TPN successfully treated with a combination of streptokinase and antibiotic therapies.

A method for the rapid production of fine plant cell suspension cultures

A method has been devised which allows the rapid production of fine suspension cultures of small aggregate size from suspension cultures of large average aggregate size, such as those of Capsicum frutescens. The method, which uses a Waring blender for aseptic homogenisation of cultures, has also been shown to be effective in rapidly producing suspension cultures from callus cultures. The suspension cultures so produced are particularly useful for immobilisation, such as in porous polyurethane foam matrices.

A microtiter cell-culture assay for the determination of anti-human immunodeficiency virus neutralizing antibody activity

A microtiter cell-culture assay is described for measuring neutralizing antibody activity directed against the human immunodeficiency virus (HIV). The assay relies upon inhibition of HIV-mediated cell killing of infected MT-4 lymphoid cells. The assay exhibits comparable sensitivity to two other methods used for such measurements, is relatively rapid, may be adapted for screening large numbers of samples and involves minimal handling of infectious virus.

Chronic neurological sequelae of acute organophosphate pesticide poisoning

To evaluate the latent neurological effects of organophosphate pesticide poisoning, this epidemiologic study examined 100 matched-pairs of individuals with previous acute organophosphate pesticide poisoning and nonpoisoned controls. No significant difference between poisoned subjects and controls was found on audiometric tests, ophthalmic tests, electroencephalograms, or the clinical serum and blood chemistry evaluations. Of the more than 50 scores from the neurological examination, abnormalities were demonstrated among the cases only on measures of memory, abstraction, and mood, and on one test of motor reflexes. Differences between the two cohorts were much more apparent in the neuropsychological tests. The differences occurred on tests of widely varying abilities including intellectual functioning, academic skills, abstraction and flexibility of thinking, and simple motor skills. Twice as many cases as controls (24 vs. 12) had Halstead-Reitan Battery summary scores in the range characteristic of individuals with cerebral damage or dysfunction. Results from the Minnesota Multiphasic Personality Inventory and the Patient's and Relative's Assessment of Patient Functioning Inventories also revealed greater distress and complaints of disability for the poisoned subjects.

Induction of an antiviral state by interferon in the absence of elevated levels of 2,5-oligo(A) synthetase and eIF-2 kinase

A series of clones has been derived from an interferon-resistant murine cell line, Ltk- aprt-, and their antiviral properties have been characterized. In the parental Ltk- aprt- line interferon is unable to establish antiviral properties or to increase the levels of 2,5-oligo(A) synthetase, the 2,5-oligo(A)-activated endonuclease F, 2',5'-phosphodiesterase, or eIF-2 kinase. However, interferon did prevent replication of vesicular stomatitis, Mengo virus, and reovirus in some of the derivative cell lines. The effect of interferon on the levels of the enzymes of the 2,5-oligo(A) and eIF-2 kinase pathways did not correlate directly with the antiviral properties of these cell clones. Greatly increased levels of 2,5-oligo(A) synthetase occurred in one clone without activation of an antiviral state. Another clone exhibited antiviral activity without detectably increased 2,5-oligo(A) synthetase activity. Changes in the levels of endonuclease F and 2',5'-phosphodiesterase were slight in all the clones examined. Neither 2,5-oligo(A) synthetase nor eIF-2 kinase levels were altered by interferon in another clone and yet an antiviral state was established and prevented replication of vesicular stomatitis, Mengo virus, and reovirus. The results show that mechanisms other than the 2,5-oligo(A) and eIF-2 kinase pathways are likely to contribute to the antiviral effects of interferon.

Cholinergic receptor mutants of the nematode Caenorhabditis elegans

Potential acetylcholine receptor (AChR) mutants of the nematode are selectable by resistance to the neurotoxic drug levamisole, a probable cholinergic agonist. To determine which mutants may have achieved resistance through loss of levamisole receptor function, we have assayed mutant extracts for specific 3H-meta-aminolevamisole binding activity in the presence and absence of mecamylamine. We find that mutants in 3 of the 7 genes associated with extreme levamisole resistance are obviously deficient in saturable specific 3H-meta-aminolevamisole binding activity. Mutants of the 4 other genes have abnormal binding activities that fail to undergo the apparent allosteric activation of saturable specific 3H-meta-aminolevamisole binding activity caused by mecamylamine. Thus, all 7 genes appear to be required to produce a fully functional levamisole receptor. Mutants of several other genes associated only with partial resistance to levamisole have at least grossly normal receptor binding activities.

Activation of metallothionein expression is potentiated by DNA sequences present in the herpes simplex virus thymidine kinase gene

A mouse cell line (Ltk-aprt-) which is resistant to the anti-viral effects of interferon also has a reduced ability to synthesize metallothionein on exposure to cadmium. Like the ability to respond to interferon, cadmium-induced metallothionein synthesis is restored to wild-type levels in clones obtained by introducing a thymidine kinase gene into Ltk-aprt-cells. Transfection of other genes does not have such an effect. Since metallothionein expression is also activated by interferon the results suggest that the regulation of several genes which are responsive to interferon can be modulated by specific sequences present in the Herpes virus thymidine kinase gene.

Parasites, diseases and health status of sympatric populations of sambar deer and white-tailed deer in Florida

From December 1983 to December 1984 a study on parasites, diseases and health status was conducted on sympatric populations of sambar deer (Cervus unicolor) and white-tailed deer (Odocoileus virginianus) from St. Vincent Island, Franklin County, Florida. Ten sambar and six white-tailed deer were examined. White-tailed deer had antibodies to epizootic hemorrhagic disease virus and bluetongue virus. Serologic tests for antibodies to the etiologic agents of bovine virus diarrhea, infectious bovine rhinotracheitis, vesicular stomatitis, parainfluenza 3, brucellosis, and leptospirosis were negative in both species of deer. White-tailed deer harbored 19 species of parasites; all were typical of the parasite fauna of this species in coastal regions of the southeastern United States. Sambar deer harbored 13 species of parasites, which apparently were derived largely from white-tailed deer. The only exception was Dermacentor variabilis which occurs frequently on wild swine on the island. The general health status of sambar deer appeared to be better than that of white-tailed deer. This was hypothesized to result from the sambar deer's utilization of food resources unavailable or unacceptable to white-tailed deer and to the absence and/or lower frequency of certain pathogens in sambar deer.

The levamisole receptor, a cholinergic receptor of the nematode Caenorhabditis elegans

We describe a glass fiber filter binding assay for the levamisole receptor, a putative acetylcholine receptor of the nematode Caenorhabditis elegans, and we show that receptor detected in vitro binds both levamisole derivatives and cholinergic agonists with the pharmacological specificity expected of the physiologically functional nematode receptor. The receptor is detected by the binding of tritiated meta-aminolevamisole ([3H]MAL, 27 Ci/mmol). In extracts of the wild-type nematode, there is a saturable, high affinity binding activity for [3H]MAL (Kd approximately 5-10 nM). Well fed wild-type worms contain as much as 3 fmol of high affinity binding activity per mg of extract protein (0.14 pmol/g of wet weight of worms) and dauer larvae, a special juvenile stage, contain as much as 15 fmol of activity per mg of protein. Specific binding activity per mg of protein is highest in larval stages and decreases severalfold in the adult worm. The rates of formation and dissociation of the [3H]MAL-receptor complex are relatively slow (dissociation half-life, 17 min), in agreement with physiological studies of levamisole on Ascaris muscle strips. Levamisole derivatives and cholinergic agonists have the same relative potencies in inhibiting [3H]MAL binding as they do in causing nematode muscle contraction. Vertebrate cholinergic antagonists do not inhibit [3H]MAL binding, but several antagonists (mecamylamine, alpha-bungarotoxin, and cobra venom) potentiate the binding of [3H]MAL and can be used to demonstrate more clearly the presence of a second, lower affinity binding activity whose ligand-binding affinity is also potentiated by these agents. Both high and low affinity wild-type binding components are missing in the extremely levamisole-resistant mutant unc-74(x19).

Migraine trials: crossover or parallel group?

This paper evaluates the relative merits of the crossover design and the parallel group design for the evaluation of migraine therapy, focussing on prophylaxis. Three issues are highlighted which lead to a preference for the parallel group trial: changes in the treatment effect with time, the possibility of carry-over effects, and the handling of withdrawals and protocol deviations. These have to be weighed against the greater power of the crossover design. It is shown that the difference in power is relatively small when baseline or run-in assessments are available. It is therefore concluded that the parallel group trial is the design of choice for prophylaxis, and that it has a place in the evaluation of acute therapy.

Genetic determinants of growth phase-dependent and adenovirus 5-responsive expression of the Chinese hamster thymidine kinase gene are contained within thymidine kinase mRNA sequences

We have constructed a chimeric thymidine kinase (TK) minigene, pHe delta 6Ha, which combines the complete coding and 3' noncoding regions of a Chinese hamster TK cDNA with the promoter region and 5' untranslated region of the TK gene of herpes simplex virus type 1. We have transformed rat 4 cells to Tk+ with this gene and analyzed the pattern of TK gene expression in these transformants under various conditions of in vitro cell culture. We find that TK gene expression in these Tk+ transformants is growth phase dependent, responsive to adenovirus 5 infection, and indistinguishable in character under a variety of cell culture conditions from the pattern of TK gene expression in rat 4 cells transformed to Tk+ with the genomic Chinese hamster TK gene clone lambda HaTK.5. We are led to the conclusion that the genetic elements which mediate growth phase-dependent TK gene expression are contained entirely within the sequences of the mature cytoplasmic hamster TK mRNA.

Structure and expression of the Chinese hamster thymidine kinase gene

My colleagues and I have cloned a nearly full-length Chinese hamster thymidine kinase (TK) cDNA in a lambda gt10 vector and characterized this cDNA by nucleotide sequencing. The hamster TK protein is encoded in this cDNA by a 702-base-pair open reading frame which specifies a 25,625-dalton protein closely homologous to the previously described human and chicken TK proteins. Using cDNA nucleotide sequence data in conjunction with sequence data derived from selected subclones of the hamster TK gene recombinant phage lambda HaTK.5, we have resolved the structure of the TK gene, finding the 1,219 base pairs of the cDNA sequence to be distributed through 11.2 kilobases of genomic DNA in at least seven exon segments. In addition, we have constructed a variety of Chinese hamster TK minigenes and exonuclease III-S1 derivatives of these genes which have permitted us to define the limits of the Chinese hamster TK gene promoter and demonstrate that efficient TK transformation of Ltk- cells by TK minigenes depends on the presence of both TK intervening sequences and sequences 3' to the site of mRNA polyadenylation.

Expression of extracellular and intracellular human IFN-gamma in mouse L cells transformed with the human IFN-gamma cDNA gene

Cotransformation with a plasmid containing a thymidine kinase gene (pTK2) and a plasmid encoding human IFN-gamma (pTG11) has been used to establish murine L cell lines expressing human IFN-gamma. The HuIFN-gamma gene was present in 30% of the tk+ cell lines and some of these secreted low levels of IFN into the culture medium. Two of the clones obtained after transformation were selected for detailed analysis. Clone 1-12 constitutively secreted very low levels of HuIFN-gamma in the culture medium. This antiviral activity was characterized by its species specificity and antigenicity as authentic human IFN-gamma In contrast, clone 3-47 produced a HuIFN-gamma activity which could only be detected intracellularly. This clone was resistant to infection both by Vesicular stomatitis (VSV) and Mengo viruses and contained increased levels of enzymes known to be induced by interferon. Our results suggest that clone 3-47 produces a non-secreted HuIFN-gamma like molecule which is able to trigger an antiviral state in the murine cell independent of the interaction with a specific IFN-gamma surface receptor.