ZFC3H1 and U1-70K promote the nuclear retention of mRNAs with 5' splice site motifs within nuclear speckles

Quality control of mRNA represents an important regulatory mechanism for gene expression in eukaryotes. One component of this quality control is the nuclear retention and decay of misprocessed RNAs. Previously, we demonstrated that mature mRNAs containing a 5' splice site (5'SS) motif, which is typically found in misprocessed RNAs such as intronic polyadenylated (IPA) transcripts, are nuclear retained and degraded. Using high-throughput sequencing of cellular fractions, we now demonstrate that IPA transcripts require the zinc finger protein ZFC3H1 for their nuclear retention and degradation. Using reporter mRNAs, we demonstrate that ZFC3H1 promotes the nuclear retention of mRNAs with intact 5'SS motifs by sequestering them into nuclear speckles. Furthermore, we find that U1-70K, a component of the spliceosomal U1 snRNP, is also required for the nuclear retention of these reporter mRNAs and likely functions in the same pathway as ZFC3H1. Finally, we show that the disassembly of nuclear speckles impairs the nuclear retention of reporter mRNAs with 5'SS motifs. Our results highlight a splicing independent role of U1 snRNP and indicate that it works in conjunction with ZFC3H1 in preventing the nuclear export of misprocessed mRNAs by sequestering them into nuclear speckles.

TPR is required for the efficient nuclear export of mRNAs and lncRNAs from short and intron-poor genes

While splicing has been shown to enhance nuclear export, it has remained unclear whether mRNAs generated from intronless genes use specific machinery to promote their export. Here, we investigate the role of the major nuclear pore basket protein, TPR, in regulating mRNA and lncRNA nuclear export in human cells. By sequencing mRNA from the nucleus and cytosol of control and TPR-depleted cells, we provide evidence that TPR is required for the efficient nuclear export of mRNAs and lncRNAs that are generated from short transcripts that tend to have few introns, and we validate this with reporter constructs. Moreover, in TPR-depleted cells reporter mRNAs generated from short transcripts accumulate in nuclear speckles and are bound to Nxf1. These observations suggest that TPR acts downstream of Nxf1 recruitment and may allow mRNAs to leave nuclear speckles and properly dock with the nuclear pore. In summary, our study provides one of the first examples of a factor that is specifically required for the nuclear export of intronless and intron-poor mRNAs and lncRNAs.

RanBP2/Nup358 enhances miRNA activity by sumoylating Argonautes

Mutations in RanBP2 (also known as Nup358), one of the main components of the cytoplasmic filaments of the nuclear pore complex, contribute to the overproduction of acute necrotizing encephalopathy (ANE1)-associated cytokines. Here we report that RanBP2 represses the translation of the interleukin 6 (IL6) mRNA, which encodes a cytokine that is aberrantly up-regulated in ANE1. Our data indicates that soon after its production, the IL6 messenger ribonucleoprotein (mRNP) recruits Argonautes bound to let-7 microRNA. After this mRNP is exported to the cytosol, RanBP2 sumoylates mRNP-associated Argonautes, thereby stabilizing them and enforcing mRNA silencing. Collectively, these results support a model whereby RanBP2 promotes an mRNP remodelling event that is critical for the miRNA-mediated suppression of clinically relevant mRNAs, such as IL6.

Concanavalin a and Wheat Germ Agglutinin Receptors in the Ascitic Fluid of Rat Hepatomas

The presence of glycopeptide lectin receptors in the ascitic fluid of rats bearing Novikoff or AS-30D hepatoma was investigated. Macrosialoglycopeptides, resistant to pronase digestion, were partially purified from the ascitic fluid of hepatoma-bearing rats by gel filtration on Sephadex G-50. A macrosialoglycopeptide fraction, isolated from the ascitic fluid of rats bearing the Novikoff hepatoma, possessed potent concanavalin A (Con A) receptor activity. This fraction possessed higher Con A receptor activity than did the comparable macrosialoglycopeptide fraction from the ascitic fluid of rats bearing the AS-30D hepatoma; this observation is in agreement with the Con A-induced agglutination properties of these 2 hepatoma cell lines and with the Con A receptor activities of the glycopeptides released from the surface of the hepatoma cells by papain digestion. Rat blood serum contained a comparable macrosialoglycopeptide fraction, which possessed weak Con A receptor activity. The macrosialoglycopeptide fractions from the ascitic fluid of hepatoma-bearing rats possessed wheat germ agglutinin receptor activity. However, this activity was also present in normal rat serum. These results suggest that glycopeptides present on the surface of Novikoff hepatoma cells are shed into the ascitic fluid and may be distinguished from components in normal serum by their Con A receptor activity.

Neonatal Escherichia coli infections in domestic mammals: transmissibility of pathogenic characteristics

Apart from the fact that different serotypes are involved, natural and experimental Escherichia coli infection in domestic mammals closely resembles natural E. coli infection in human beings. Some of the important characteristics of E. coli strains that cause disease in domestic mammals are determined by transmissible plasmids. These include enterotoxin, haemolysin and K88 antigen in piglet enteropathogenic strains and enterotoxin and K99 antigen production in calf and lamb enteropathogenic strains; most strains that cause generalized infections in young domestic mammals, i.e. invasive strains, also produce plasmid-determined colicine V. These are all good reasons for employing young domestic mammals as the animal model for studying certain aspects of E. coli infection in human beings. Exploiting the fact that plasmids can be introduced into bacterial cells by conjugation and can be removed from them by "curing", bacterial strains were created that differed from each other, as far as could be determined, only by the presence or absence of one or more of these plasmid-determined properties. These strains, or cell-free preparations of them, were then given by mouth to piglets, calves, lambs and baby rabbits. The results showed that the K88 antigen, probably on account of its adhesive properties, permitted pig enteropathogenic strains of E. coli to proliferate in the small intestine of piglets; the K99 antigen performed a similar function in calf and lamb enteropathogenic strains. The enterotoxin produced by the proliferating organisms was then chiefly responsible for the subsequent movement of fluid from the body into the small intestine and the consequent diarrhoea. Possession of the Col V plasmid contributed significantly to the virulence of invasive strains of E. coli by enabling them to resist more successfully the defence mechanisms of the host.

Mild hypoxia is associated with quantitative EEG changes, but not with dissociative symptoms

<p><strong>Backround and aims.</strong> Hypoxia at altitude may lead to mental changes resembling dissociative symptoms. This study examined whether hypoxia precipitates dissociative states in normal subjects and whether quantitative electro- encephalographic (EEG) changes occur.</p><p><strong>Methods.</strong> Dissociative symptoms and EEG changes were examined in a hypobaric chamber. <strong></strong></p><p><strong>Results.</strong> No dissociation was noted. EEG slowing accompanied hypoxia, replicating previous findings.</p>

Immunogenicity of biopharmaceuticals in laboratory animals

The potential immunogenicity of new protein therapeutics raises concerns about the possibility of inducing untoward immune reactions in humans. It is generally assumed that all animals will make antibody to human proteins and therefore, there is sentiment among some scientists that this makes the issue of immunogenicity as a safety concern irrelevant. However, recent clinical trials with some proteins have detected the presence of autoantibodies that have resulted in clinical sequelae. These reactions were also observed in preclinical animal studies. In fact, non-human primate and transgenic mouse models can be useful for predicting the relative immunogenicity of human proteins. In addition, the characterization of the immunogenicity of biotechnology molecules provides a practical basis for determining the significance of antibody formation in preclinical safety studies.

Immunogenicity of tissue plasminogen activators in rhesus monkeys: antibody formation and effects on blood level and enzymatic activity

The immunogenicity of a tissue-type plasminogen activator analog, mt-PA6, consisting of the second kringle and protease domains, was compared to that of the native-sequence protein (nt-PA) in rhesus monkeys. Antibody responses were compared in groups of eight monkeys that were treated by i.v. injection twice, 1 month apart, using doses and regimens chosen to mimic therapy (0.5 mg/kg mt-PA6 bolus, 1.25 mg/kg nt-PA bolus + infusion). An additional group was treated with a 0.5 mg/kg nt-PA bolus. A single positive response was obtained in a monkey treated with 0.5 mg/kg nt-PA after the primary injection. Following the secondary injection, responses were obtained in 1/8, 3/8, and 6/8 monkeys treated with mt-PA6, nt-PA as a bolus, or nt-PA as a bolus + infusion, respectively. Several monkeys were selected to determine whether circulating tPA antibody altered the pharmacokinetics of mt-PA6. Clearance was found to decrease without affecting peak blood levels as antibody concentrations increased from 0.02 to 100 micrograms/ml. In contrast, the peak blood level was reduced by 99% at an antibody concentration of 152 micrograms/ml in a monkey that had been exposed to mt-PA6 in adjuvant 14 months previously. Further, only the serum from this and three other hyperimmunized monkeys inhibited the enzymatic activity of tPA in vitro. It is concluded that mt-PA6 is not more immunogenic than nt-PA in rhesus, and that low levels of antibody are more likely to influence the pharmacokinetic properties of tPA than to inhibit its enzymatic activity. It is unlikely that mt-PA6 would present a serious immunogenic risk in humans.

Immunogenicity of biosynthetic human LysPro insulin compared to native-sequence human and purified porcine insulins in rhesus monkeys immunized over a 6-week period

Development of insulin antibodies in rhesus monkeys was investigated after immunization with 3 forms of insulin in Freund's adjuvant. Insulins examined included: 1. biosynthetic LysPro insulin (LY275585), a new human insulin analog, 2. biosynthetic native-sequence human insulin, and 3. purified porcine insulin. Male monkeys, 4/insulin type, were immunized weekly over a 6-week period with increasing doses of insulin, ranging from 10 to 100 micrograms/monkey. An ELISA assay was used to measure IgG insulin antibodies in sera collected prior to immunization and 5, 10, and 16 days after final immunization. One monkey had detectable pretreatment levels of antibody. This monkey, which had been assigned to the LysPro insulin treatment group, responded to immunization with a peak antibody level of 20 micrograms/ml. IgG insulin antibody responses were not detected in any of the other monkeys. A passive cutaneous anaphylaxis (PCA) assay was used to measure IgE insulin antibodies in sera collected prior to immunization and 10 days after final immunization. No IgE antibodies were detected in any of the monkeys pre- or post-immunization. Considering that 1. an immunological adjuvant was used, 2. eleven of twelve monkeys failed to develop an antibody response, and 3. the IgG insulin antibody level observed in the single responding monkey was low, it was concluded that these insulins have an extremely weak immunogenic potential in rhesus monkeys. It is suggested that immunization of non-human primates with new therapeutic proteins in adjuvant may be a useful primary screen to determine their immunogenic potential.(ABSTRACT TRUNCATED AT 250 WORDS)

Discovery, synthesis, and bioactivity of bis(heteroaryl)piperazines. 1. A novel class of non-nucleoside HIV-1 reverse transcriptase inhibitors

A variety of analogues of 1-[4-methoxy-3,5-dimethylbenzyl]-4-[3-(ethylamino)-2-pyridyl]piperazine hydrochloride (U-80493E) were synthesized and evaluated for their inhibition of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT). Replacement of the substituted aryl moiety with various substituted indoles provided bis(heteroaryl)piperazines (BHAPs) that were 10-100-fold more potent than U-80493E. The pyridyl portion of the lead molecule was found to be very sensitive to modifications. Extensive preclinical evaluations of several of these compounds led to the selection of 1-[(5-methoxyindol-2-yl)carbonyl]-4-[3-(ethylamino)-2- pyridyl]piperazine methanesulfonate (U-87201E, atevirdine mesylate) for clinical evaluation.

Cleft lip and palate surgery in La Ceiba, Honduras

The volume of experience in the surgical repair of cleft lip and palate deformities is limited in many areas of the United States. This deficit in experience exists not only for those in resident training programs but also for those who practice at universities or are in private practice. Physicians are performing too few operations to maintain their surgical skills in cleft lip and palate surgery. This deficit is also encountered by physicians in the major specialties of plastic surgery, oral surgery, and otolaryngology who perform cleft lip and palate surgery. Physicians from the United States can gain surgical experience in other countries through groups like the Medical Group Mission Christian Medical and Dental Society. Surgical experience is available in Central and South America, India, China, and Africa through similar organizations. The complexity of providing service to under-privileged people through organizations such as the Medical Group Mission Christian Medical and Dental Society is described.

Contribution of leukotriene B4 to airway inflammation and the effect of antagonists

Inhalation of aerosols of ovalbumin in sensitized guinea pigs produced a marked, bronchoalveolar eosinophilia 24 hr after challenge. The lung eosinophilia was not prevented by the cyclooxygenase inhibitors, indomethacin or PAF antagonists (WEB-2086 and L-652731) but was inhibited by methylprednisolone, the 5-LO inhibitor, U-66858 and a series of structural analogs of LTB4, U-75302, U-77692, U-75485 and U-78489. The effectiveness of LTB4 antagonists but not PAF antagonists in vivo was consistent with in vitro studies in which LTB4 was shown to be far more chemotactic than PAF for guinea pig eosinophils. LTB4 elicited maximal directional migration of guinea pig eosinophils at concentrations from 10(-7) M to 10(-9) M while PAF showed no effect over the same concentration range. The structural analogs of LTB4 were shown to inhibit LTB4 induced chemotaxis of guinea pig eosinophils and produced a dose-related inhibition of binding of LTB4 to guinea pig eosinophil membranes. To add further proof to the hypothesis that LTB4 contributed to the antigen-induced lung eosinophilia we attempted to measure LTB4 release into BAL fluid immediately after and at various time points up to 24 hr after antigen inhalation. However, using a sensitive radioimmunoassay (detection limit 10 pg/ml) very low levels of LTB4 (24.9-67.9 pg/ml) or its metabolite, 20-OH LTB4 (24.9-98.2 pg/ml) were detected in BAL fluid and these levels did not increase significantly following antigen provocation. Inhalation of LTB4 aerosols in unsensitized Brown-Norway rats or inhalation of aerosols of ovalbumin in sensitized Brown-Norway rats also produced a marked "late-phase" eosinophil-rich influx of inflammatory cells into the lungs. The lung eosinophilia in the rat was prevented by two structurally unrelated leukotriene B4 (LTB4) antagonists, U-75302 and Ly255283. These data implicate LTB4 as a mediator of allergen-induced bronchopulmonary eosinophilia. Leukotriene B4 antagonists may provide leads for the development of compounds which inhibit the chronic airway inflammation associated with asthma in man.

Biochemical manifestations of oxygen toxicity in the newborn lamb

The purpose of this project was to study the role of lipid peroxidation in oxygen-induced lung injury in the newborn lamb. It was our hypothesis that injury to the microvascular bed of the lung by oxygen would coincide with a burst of peroxidative activity and would be accompanied by an increased rate of excretion of ethane and pentane in expired gas. We measured vascular pressures, the rate of lung lymph flow and concentrations of ethane and pentane in exhaled gas in 10 newborn lambs that breathed greater than 95% oxygen continuously. Our marker for oxygen-induced lung injury was an increase in the permeability of the microvascular bed of the lung to protein (an increase in the rate of lung lymph flow accompanied by an increase in the protein concentration in lymph). Although all 10 lambs demonstrated an abrupt increase in microvascular permeability to protein within 48 to 96 h of exposure to greater than 95% oxygen, the rates of ethane and pentane excretion remained unchanged throughout the entire experimental period. Lung tissue concentrations of glutathione decreased by 40% in the oxygen-exposed lambs and the concentrations of glutathione disulfide increased 85% relative to air-breathing controls. Activities of glutathione reductase and superoxide dismutase were lower in the lungs of the oxygen-exposed lambs than in controls, whereas the activities of glutathione peroxidase and catalase were not changed. We conclude that, in the lamb, changes in the rates of excretion of ethane and pentane do not correlate with the timing of injury to the microvascular bed of the lung.

Somatotropin antibody formation in cows treated with a recombinant bovine somatotropin over two lactations

Blood plasma from cows treated with somidobove, a form of recombinant bovine somatotropin, was assayed for development of antibodies against the protein. Forty-three Holstein cows, selected from an animal safety study, were monitored. Cows were divided into four groups and treated with placebo, 960, 2880, or 4800 mg somidobove per dose at 28-d intervals during two successive lactation periods. Blood plasma was collected at intervals prior to and during the lactations, and levels of IgG antibody reactive with somidobove were determined in an enzyme-linked immunosorbent assay. Virtually all of the cows treated with somidobove developed low levels (less than 40 micrograms/ml) of antibody against somidobove. One or two cows from each group responded with some-what higher levels, ranging from 40 to 200 micrograms/ml. Responses generally increased during the first 3 mo of treatment, then decreased, and remained constant with continued treatment. There was no sign of a memory response within or among the lactation periods, and no adverse health effects or decreases in lactational performance were associated with antibody production.

Protein crystal growth in microgravity

The crystals of most proteins or other biological macromolecules are poorly ordered and diffract to lower resolutions than those observed for most crystals of simple organic and inorganic compounds. Crystallization in the microgravity environment of space may improve crystal quality by eliminating convection effects near growing crystal surfaces. A series of 11 different protein crystal growth experiments was performed on U.S. space shuttle flight STS-26 in September 1988. The microgravity-grown crystals of gamma-interferon D1, porcine elastase, and isocitrate lyase are larger, display more uniform morphologies, and yield diffraction data to significantly higher resolutions than the best crystals of these proteins grown on Earth.

Ethical use of Yellow Pages listings by physicians

A recent article in the New England Journal of Medicine examined the percentage of physicians listed under specialty headings in a Yellow Pages publication who were board certified. The authors presented findings that many of the physicians listed in the Yellow Pages, particularly under the heading of "Plastic Surgery," were not board certified. The source data employed in that article were obtained and reexamined, and it was found that the assumptions used were inaccurate and the methodology flawed. Almost every physician listed under "Plastic Surgery" in the Yellow Pages is board certified. We discuss the conclusions of the original article and its recommendations for control of Yellow Pages listings. We believe that these recommendations are not in the public's best interests and may be illegal as well.

Acute myocardial infarction temporally related to cocaine use. Clinical, angiographic, and pathophysiologic observations

Ischemic chest pain syndromes and myocardial infarction occurred within minutes to hours of cocaine use in nine persons ages 23 to 39 years. Five developed symptoms after taking cocaine intranasally; three, after intravenous use; and one, after smoking cocaine. Four were habitual users and five were recreational users; eight also smoked cigarettes heavily. Ischemic syndromes recurred in five who continued to use cocaine. Coronary arteriography showed an abnormal infarct-related vessel (more than 50% stenosis, total occlusion, or intraluminal thrombus) in seven patients. The noninfarct-related vessels were normal in eight patients. The left anterior descending coronary artery and the anteroapical left-ventricular wall were involved in all patients. After three patients had successful thrombolysis of the obstructed infarct-related vessel, angiography showed a normal underlying vessel.

Factors influencing the survival and multiplication of bacteriophages in calves and in their environment

Seven phages were fairly susceptible in vitro to the lethal effect of acidified whey, more so than the enteropathogenic Escherichia coli strains on which they were active. The low acidity that prevailed in the abomasum contents of calves shortly after a milk feed had little harmful effect on orally administered organisms of these phages; they flooded into the small intestine. The high acidity that prevailed later was lethal to orally administered phage organisms; few entered the small intestine. The lethal effect could be counteracted by giving CaCO3 in the feed. Low concentrations of phage-neutralizing antibodies were found in some serum samples from human beings, cattle and pigs. Antibodies to one of the seven phages were common in the human samples and antibodies to another, phage B44/1, were common in the cattle and pig samples and in bovine colostrum. Phage B44/1 antibodies in a sample of colostral whey were destroyed at pH 3.25 or less. Giving colostrum containing phage B44/1 antibodies with CaCO3 to a calf greatly reduced the numbers of orally administered phage B44/1 organisms in its alimentary tract. Antibodies to another phage were induced in the serum of a calf suffering from E. coli diarrhoea by treating it with that phage. The phages were as susceptible as the E. coli strains to the lethal action of formaldehyde and sodium hypochlorite. In contrast to the E. coli strains, they were almost completely resistant to phenol and chloroxylenol. The in vitro virulence of 21 phages varied according to the temperature at which tests were performed.(ABSTRACT TRUNCATED AT 250 WORDS)

The control of experimental Escherichia coli diarrhoea in calves by means of bacteriophages

Seven phages highly active in vitro and in vivo against one or other of seven bovine enteropathogenic strains of Escherichia coli belonging to six different serotypes were isolated from sewage. Severe experimentally induced E. coli diarrhoea in calves could be cured by a single dose of 10(5) phage organisms. It could be prevented by doses as low as 10(2), by spraying the litter in the calf rooms with aqueous phage suspensions or simply by keeping the calves in uncleaned rooms previously occupied by calves whose E. coli infections had been treated with phage. Microbiological examinations of calves used in these experiments revealed that the phage organisms multiplied rapidly and profusely after gaining entry to the E. coli-infected small intestine, quickly reducing the E. coli to numbers that were virtually harmless. The only phage-resistant E. coli that emerged in the studies on calves infected with one or other of the seven E. coli strains were K-. These organisms were much less virulent than the K+ organisms from which they were derived and did not present a serious problem in calves given adequate amounts of colostrum. Infections produced by oral inoculation of a mixture of six strains of the E. coli could be controlled by administration of a pool of the six phages that were active against them but, in general, the control was less complete than that observed in the single-strain infections. K+ phage-resistant bacteria emerged in some of the calves used in these mixed infections and they were as virulent as their parent organisms; evidence from in vitro studies suggested that they might have arisen by genetic transfer between organisms of the different infecting strains. Infections produced by these K+ mutants and their parents could be controlled by the use of mutant phages derived from phages that were active on their parents. During the experiments with mixed E. coli infection, an extraneous phage active against one of the six E. coli strains suddenly appeared in calves kept in the same rooms. Microbiological examinations revealed that this phage was effectively controlling the multiplication of organisms of that particular strain of E. coli in the small intestines of the calves.

Two toxin-converting phages from Escherichia coli O157:H7 strain 933 encode antigenically distinct toxins with similar biologic activities

Escherichia coli O157:H7 strain 933 contains two distinct toxin-converting phages (933J and 933W). The biologic activities and antigenic relationship between the toxins produced by 933J and 933W lysogens of E. coli K-12, as well as the homology of the genes that encode the two toxins, were examined in this study. The 933J and 933W toxins, like Shiga toxin produced by Shigella dysenteriae type 1, were cytotoxic for the same cell lines, caused paralysis and death in mice, and caused fluid accumulation in rabbit ileal segments. The cytotoxic activity of 933J toxin for HeLa cells was neutralized by anti-Shiga toxin, whereas the activity of 933W toxin was not neutralized by this antiserum. In contrast, an antiserum prepared against E. coli K-12(933W) neutralized 933W toxin but not 933J toxin or Shiga toxin. For E. coli 933, most of the cell-associated cytotoxin was neutralized by anti-Shiga toxin, whereas most of the extracellular cytotoxin was neutralized by anti-933W toxin. However, a mixture of these antisera indicated the presence of both toxins in cell lysates and culture supernatants. Among 50 elevated cytotoxin-producing strains of E. coli, we identified 11 strains isolated from cases of diarrhea, hemorrhagic colitis, or hemolytic uremic syndrome that produced cell-associated cytotoxins which were neutralized by the 933W antitoxin. Southern hybridization studies showed that the cloned toxin structural genes from phage 933J hybridized with DNA from phage 933W under conditions estimated to allow no more than 26% base-pair mismatch. These findings indicate that E. coli produces two genetically related but antigenically distinct cytotoxins with similar biologic activities which we propose to name Shiga-like toxins I and II. Strains of E. coli that produce elevated levels of Shiga-like toxin I or Shiga-like toxin II, or both, have been associated with the clinical syndromes of diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome.

Infectious bronchitis immunity: its study in chickens experimentally infected with mixtures of infectious bronchitis virus and Escherichia coli

The live infectious bronchitis (IB) vaccine, H120, protected chickens against intranasal challenge with a mixture of Escherichia coli strains (E. coli Pool) and IB virus (IBV) strains of the same (Massachusetts) serotype as H120; it usually also protected against challenge with the E. coli Pool and IBV strains of other serological types. When these challenge strains were themselves used as vaccines they usually protected against challenge with a mixture of the E. coli Pool and an IBV strain of the Massachusetts serotype (VF69-149) or an IBV strain not of the Massachusetts serotype (HVI-116). Poor protection, when observed, was most common in those experiments involving a minority of the IBV strains that had been incriminated in recent outbreaks of disease in vaccinated flocks of chickens. Much lower concentrations of IBV strain VF69-149 and E. coli O18 were found in the nose, trachea and spleen of H120-vaccinated chickens killed at different times after they were given a mixture of these organisms than were found in these sites in similarly challenged unvaccinated chickens. Some protection against challenge with IBV and the E. coli Pool was also observed in chickens vaccinated with an inactivated IBV strain; it was much less effective than that obtained following vaccination with the corresponding live IBV strain.

Effect of Piriprost, a 5-lipoxygenase inhibitor, on leukocyte accumulation during thioglycollate-induced acute inflammation

We evaluated the effect of a prototype 5-lipoxygenase enzyme inhibitor, Piriprost [6,9-deepoxy-6,9-(phenylimino-)delta 6,8-prostaglandin I1], on the leukocyte accumulation induced by intraperitoneal injection of thioglycollate in rats. Piriprost, at 40 mg/kg, i.p., inhibited leukocyte accumulation by 34 +/- 12% (mean +/- S.D., n = 9). With experimental groups containing small numbers of rats (6 to 9) inhibition was statistically significant in 7 of 9 cases. Piriprost shared this property with dexamethasone; however, dexamethasone at 5 mg/kg, p.o., inhibited leukocyte accumulation to a greater extent, 61 +/- 6% (mean +/- S.D., n = 5) and the inhibition was statistically significant in 5 of 5 cases. Conventional non-steroidal antiinflammatory agents including aspirin and phenylbutazone were ineffective in our model. Our results suggest that certain compounds that inhibit the 5-lipoxygenase enzyme, without inhibiting the cyclooxygenase enzyme, can reduce the leukocyte accumulation associated with acute inflammation.

Crystal structure of quinespar, a quinazoline analogue of methotrexate

The molecular structure of quinespar, a quinazoline analogue of methotrexate and aminopterin, has been determined by X-ray crystallography. The molecule displays an extended conformation with the p-aminobenzoyl plane rotated 66 degrees from the plane of the quinazoline. The orientation of the quinazoline ring relative to the rest of the molecule is intermediate between the orientations of the comparable pteridine rings in folic acid and in DHFR-bound methotrexate. Evidence is presented to suggest that 2,4-diaminoquinazolines bind to DHFR in the same manner as do 2,4-diaminopteridines.

Acquisition of genes from an O18:K1:H7 ColV+ strain of Escherichia coli renders intracranially-inoculated E. coli K12 highly virulent for chickens, ducks and guinea-pigs but not mice

The virulence of intracranially-inoculated mutant forms of an O18ac:K1:H7 ColV+ strain of Escherichia coli (designated MW) that lacked different combinations of its O and K antigens and ColV, and of an E. coli K12 strain to which these characters had been transmitted was studied in mice, chickens, ducks and guinea-pigs. The O18+K1+ColV+ form of MW was highly virulent for chickens and mice but the corresponding form of K12 was only highly virulent for chickens; the O18-K1-ColV- forms of both strains were of low virulence for chickens and mice. K1 was more important than O18 or ColV in determining virulence for both animal species. Ducks and guinea-pigs resembled chickens, not mice, in their response to infection with the O18+K1+ColV+form of K12. Pathogenesis studies revealed that the virulence of the forms of MW and K12 was associated with their ability to proliferate in the central nervous system; only low numbers of organisms were found in the blood and spleen of inoculated animals. The O18+K1+ColV+ form of K12 multiplied in mouse brain and in mouse blood in vitro; its multiplication in chicken blood was partially inhibited. Agglutinins to this and other forms of K12 were found in chicken serum but not in mouse serum. Large doses of mouse serum given to chickens and large doses of chicken serum given to mice did not alter the manner in which these animals responded to K12 O18+K1+ColV+ infection. Vaccination protected chickens and mice against lethal intracranial infection with the O18+K1+ColV+ forms of K12 or MW; it produced a much stronger immunity in mice against intraperitoneal challenge than against intracranial challenge.

Transduction complicates the detection of conjugative ability in lysogenic salmonella strains

When lysogenic salmonella strains were examined for conjugative ability in tri-parental crosses, false positive results were sometimes obtained because phage carried by the lysogenic strains multiplied on the intermediate salmonella recipient strain and then transduced its streptomycin/sulphonamide resistance plasmid to the final salmonella recipient strain. Back transfer of the plasmid to the lysogenic strains was also detected.

The experimental infection of chickens with mixtures of infectious bronchitis virus and Escherichia coli

By inoculating chickens intranasally with a collection of strains of infectious bronchitis virus (IBV) of the Massachusetts serotype and of Escherichia coli of different serotypes, a pool of viral and bacterial strains was selected which, on inoculation, consistently produced a highly lethal disease closely resembling the natural disease produced by these two organisms. The conditions for reproducing the experimental disease were not rigorous in that, within broad limits, the size of the viral and bacterial inocula were not important; neither were the times at which both organisms were administered in relation to each other. The breed or strain of chicken used was important and the resistance of chickens to fatal infection increased with age. When the E. coli strains of the pool were inoculated intranasally without the IBV component, the chickens remained well; bacteriological examination of chickens inoculated with one of the E. coli strains, O18, revealed little evidence of invasion of the tissues or even of persistence of the inoculated E. coli strain in the upper respiratory tract. A minority of the IBV strains examined were lethal for chickens when inoculated without E. coli but many of them only produced a substantial mortality when the E. coli were included in the inoculum; IBV strains in this latter category included the vaccine strains H52 and H120. High concentrations of IBV strain M41 and E. coli O18 persisted in the upper respiratory tract for a number of days after they had been inoculated together. Much lower concentrations of IBV M41 were found in the internal organs, such as the spleen; E. coli O18 was only found in these sites in some of the inoculated chickens. Coliform organisms proliferated in the upper respiratory tract of chickens inoculated with IBV alone; they were rarely found in their internal organs.

The toxic role of alpha-haemolysin in the pathogenesis of experimental Escherichia coli infection in mice

Filtrates from strains of Escherichia coli possessing plasmid-cloned haemolysin (Hly) genes and from strains possessing 'wild' Hly plasmids were lethal for mice on intravenous inoculation; similar doses of preparations from derivatives of these strains in which the Hly genes had been rendered non-functional or which did not possess the 'wild' plasmids were not. Live cultures of both kinds of Hly+ strain usually had a lower lethal dose for mice on intraperitoneal inoculation than the corresponding Hly- forms. Mice that had been inoculated with Hly+ forms had shorter survival times and lower numbers of organisms in peritoneal washings, lungs and blood at point of death than mice that had been inoculated with the corresponding Hly- forms; this was also so for mice pre-treated with FeSO4, a procedure which rendered mice equally susceptible to the lethal effects of the Hly+ and Hly- forms of a strain. In FeSO4-treated mice the numbers of organisms in the tissues of those dying from infection with Hly+ organisms were no higher than they were at the same time after inoculation in others given the corresponding Hly- forms; before mice of the latter category died the numbers of organisms in their tissues increased greatly. The clinical and pathological signs exhibited by mice inoculated with Hly+ organisms, but not with Hly- organisms, resembled those exhibited by mice inoculated with bacteria-free haemolysin preparations. These results suggest that haemolysin played a significant role in the pathogenesis of the disease produced by the Hly+ organisms by having a direct toxic action on the host.

The effect of feeding diets containing avoparcin on the excretion of salmonellas by chickens experimentally infected with natural sources of salmonella organisms

Chickens were readily infected with salmonella organisms when fed diets containing unsterilized bone-meal or provided with drinking water containing a suspension of natural salmonella infected chicken faeces. When fed diets containing avoparcin at concentrations of 10 or 100 mg/kg chickens infected in these ways excreted larger numbers of salmonellas for longer periods than did chickens fed a nonmedicated diet.