The alpha chemokine, interleukin 8, inhibits the antiviral action of interferon alpha.

Interferon (IFN) exhibits a potent antiviral activity in vitro and plays a major role in the early defense against viruses. Like IFN, the proinflammatory chemokine, interleukin (IL)-8, is induced by viruses and appears in circulation during viral infections. In an in vitro cytopathic effect assay for IFN, we found that IL-8 can inhibit IFN-alpha activity in a dose-dependent manner. This action was reversed by specific monoclonal antibodies to IL-8. The chemokine was able to attenuate the IFN-mediated inhibition of viral replication as determined by measuring infectious virus yield. IL-8 also diminished the ability of IFN to inhibit an early stage of viral replication since IL-8 attenuated the inhibition of the formation of viral proteins. It appeared that IL-8 interfered with a late rather than an early step of IFN-mediated pathway such as early gene expression. The IL-8 inhibitory action on IFN-alpha antiviral activity was associated with reduced 2',5'-A oligoadenylate synthetase activity, a pathway well correlative with the anti- encephalomyocarditis virus action of IFN-alpha. Understanding pathways that antagonize IFN action may lead to novel approaches to potentiate endogenous and therapeutic IFN.

Effect of deficiency of the double-stranded RNA-dependent protein kinase, PKR, on antiviral resistance in the presence or absence of ribonuclease L: HSV-1 replication is particularly sensitive to deficiency of the major IFN-mediated enzymes.

Control of viral replication by interferon (IFN) is thought to be principally mediated by the 2',5'-oligoadenylate synthetase (OAS)/RNAse L, double-stranded dependent protein kinase (PKR), and myxovirus resistance protein (Mx) pathways. In this study, we monitored the constitutive and IFN-induced antiviral activity in mouse embryo fibroblasts lines derived from mice with targeted disruption of either PKR or PKR/RNAse L genes. At high multiplicity of infection (moi = 10), the absence of PKR had no effect on replication of vesicular stomatitis virus (VSV) but moderately enhanced encephalomyocarditis virus (EMCV) growth and greatly increased replication of herpes simplex virus-1 (HSV-1). Replication of EMCV, HSV-1, and VSV was modestly higher in PKR-/- RNAse L-/- fibroblasts when compared with control cells. Although the antiviral action of IFN-alpha was unaffected by the absence of PKR, IFN action was significantly impaired in the double knockout cells but was dependent on the stage of the virus cycle. At early stages, it appeared that anti-EMCV and anti-HSV-1 action of IFN-alpha was significantly compromised, although weak residual antiviral activity was seen. The action of IFN-alpha against VSV was specifically compromised at a late stage of virus replication. The results showed that PKR is an important mediator in constitutive resistance against HSV-1 and that RNAse L is also necessary for the full antiviral activity of IFN against a variety of viruses. These results supported the existence of novel pathways aimed toward specific stages of the virus life cycle.

Aspartoacylase deficiency and Canavan disease in Saudi Arabia.

We found defective aspartoacylase activity in fibroblasts cultured from 12 patients with leukodystrophy clinically diagnosed as spongy degeneration of the brain (Canavan disease), three confirmed by brain biopsy. The activity of aspartoacylase ranged between 1 and 13% of two groups of control individuals, normals, and those with other leukodystrophies. The present report confirms the study of Matalon et al. [1988] in a totally different ethnic group and provides independent verification that aspartoacylase activity is the first documented specific biochemical marker in Canavan disease and plays an important role in pathogenesis. Considering that only some 75 cases had been reported up to 1982, our group of 12, accumulated within 3 years, is inordinately large and suggests that Saudi Arabia provides a promising venue in which to study the biochemical and molecular genetics of Canavan disease.

Treatment of severe pertussis: a study of the safety and pharmacology of intravenous pertussis immunoglobulin.

BACKGROUND: Pertussis in infants is often severe, resulting in complications and prolonged hospitalization. Treatment is limited to supportive care. Antibiotics do not significantly alter the course of the disease. Therapies directed at pertussis toxin, a major virulence factor of Bordetella pertussis, might be beneficial. This study examines the safety and pharmacology of intravenous pertussis immunoglobulin (P-IGIV), which has high levels of pertussis toxin antibodies. METHODS: P-IGIV was prepared as a 4% IgG solution from the pooled plasma from donors immunized with inactivated pertussis toxoid. The IgG pertussis toxin antibody concentration of 733 microg/ml is >7-fold higher than contained in conventional intravenous immunoglobulin products. Children with presumptive pertussis were allocated to one of three treatment doses of P-IGIV. RESULTS: Twenty-six of 30 enrolled children had confirmed pertussis. There were no adverse events associated with P-IGIV except one patient who had transient hypotension that responded to an infusion rate decrease. P-IGIV doses of 1500, 750 and 250 mg/kg achieved > or =4-fold, 3-fold and >2-fold rises in peak geometric mean titers of pertussis toxin IgG antibodies, respectively. P-IGIV exhibited a half-life of 38.4 days and a volume of distribution of 87.8 ml/kg. All three treatment groups showed declines in lymphocytosis (P < 0.05) and paroxysmal coughing by the third day after P-IGIV infusion compared with preinfusion values. CONCLUSION: P-IGIV is safe and achieves high pertussis toxin antibody titers in infants. This study provides data for a prospective, controlled trial of P-IGIV.

The diagnosis and management of MSUD in Saudi Arabia by using two different methods.

Plasma amino acid concentrations were measured in Maple Syrup Urine Disease (MSUD) infants using reversed phase high performance liquid chromatography (HPLC). The technique involved an automated data acquisition system and phenylisothiocyanate (PITC) pre-column derivatization. During a period of three years more than 14 cases of MSUD have been confirmed in our hospital suggesting an alarmingly high rate of incidence of this disease in the Kingdom as compared to the West. We present here a simple and reliable method of quantitating the branched chain and other amino acid concentrations in plasma samples of children with metabolic disorders. In addition, we also present a fluorimetric COBAS based enzymatic method for the rapid semiquantitative measurement of branched chain amino acids for a disease in which a prompt initial diagnosis is essential.

In vivo studies of unlabeled and radioiodinated rhodamine-123.

Radioiodinated rhodamine-123 (Rh123), potential tumor imaging agent, was injected in mice bearing experimentally-induced tumors to investigate its tissue distribution. Some accumulation of radioactivity was found in tumors; most of it cleared rapidly from the blood after injection. Also, the radioiodinated Rh123 had metabolized to water-soluble species which was excreted in urine and feces. Unlabeled Rh123, on the other hand, accumulated only marginally in the tumors. However, it was found to accumulate significantly in the heart; as much as seventy times the level in blood at 4 h post-injection. Accumulation of unlabeled Rh123 increased steadily even at 24 h post-injection; whereas, it cleared rapidly from the blood via the kidney. This finding of selective accumulation of Rh123 in heart could be exploited in synthesizing 11C- and 18F-labeled Rh123 for use in PET studies of the myocardium.

Does a third year of emergency medicine training make a difference? Historical cohort study of Queen's University graduates.

OBJECTIVE: To describe outcomes of a third-year residency (PGY-3) program in family medicine/emergency medicine in terms of its graduates' practice characteristics and their self-assessed preparedness for practising emergency medicine. DESIGN: A questionnaire was sent to graduates of Queen's University's family medicine residency programs. SETTING: Recent graduates' practices. PARTICIPANTS: All 30 graduates of Queen's University's Family Medicine/Emergency Medicine Program (PGY-3s) from 1988 to 1997 and 90 matched controls chosen randomly from among the 250 graduates of the 2-year family medicine residency program (PGY-2s) during the same period. Six of the 120 were excluded. Response rate was 89%. MAIN OUTCOME MEASURES: Current practice of family and emergency medicine, leadership activities in emergency medicine, self-assessment of preparedness to practise and to lead others at the end of training, self-report of frequency of emergency care situations in subsequent practice for which physicians felt unprepared by their training, and catchment population and "rurality" of location of current practice. RESULTS: Compared with controls, more PGY-3s practiced and took leadership roles in emergency medicine in their hospitals and communities. At the end of their training, PGY-3s reported higher levels of preparedness for practicing and providing leadership in emergency medicine. Both groups reported the same frequency of encountering emergency situations in subsequent practice for which they felt inadequately prepared. Both groups practised in communities of similar size and location. CONCLUSION: Graduates of Queen's University's third-year emergency medicine program appear to practise in accordance with their extra training.

Prevalence of different types of lysosomal storage diseases in Saudi Arabia.

The frequency of different types of lysosomal storage diseases in 125 referred cases, collected over three years, was compared to the occurrence elsewhere. The data suggest that mucopolysaccharidosis (MPS) type IVA (Morquio disease), multiple sulphatase deficiency, Niemann-Pick disease type B, GM2 gangliosidosis type '0' (Sandhoff disease), and ceroid lipofuscinosis (Jansky-Bielschowsky and Batten-Spielmeyer-Vogt syndromes) are encountered frequently in Saudi Arabia, as compared to other storage diseases. In contrast, some other diseases such as the adult variant of Gaucher's disease were not observed. Half of the GM2 gangliosidosis type '0' cases originated from one large tribe in the country. Other conditions did not show tribal predilection. The ceroid lipofuscinosis cases in Saudi Arabia originated from four large families. Consanguineous marriages taking place within tribal boundaries probably account for the pattern observed.

Interleukin-8 selectively enhances cytopathic effect (CPE) induced by positive-strand RNA viruses in the human WISH cell line.

Interleukin-8 (IL-8), a proinflammatory chemokine, is induced by viruses and appears in circulation during viral infections. We found that IL-8 enhanced cytopathic effect induced by the positive strand RNA virus, encephalomyocarditis virus (EMCV), in the human WISH cell line. The enhancement was dependent on IL-8 dose and virus dose and was reversible by specific monoclonal antibodies to IL-8. The chemokine was also able to increase EMC viral RNA synthesis and infectious virus yield. This IL-8 enhancing action was not observed in the case of the negative strand RNA virus, vesicular stomatitis virus (VSV), in WISH cells. We examined the activity of constitutive 2',5'-oligoadenylate synthetase (OAS), a pathway that was implicated in protection from EMCV but not VSV. The IL-8 action in EMCV-infected cells, unlike VSV-infected cells, was associated with decreased OAS activity in a manner that was independent of OAS gene expression. Understanding mechanisms of cytokine enhancement of viral activity may lead to novel ways to control viral infections.