PAF-induced airway responses in sheep: effects of a PAF antagonist and nedocromil sodium

Platelet-activating factor (PAF) is a potent inflammatory mediator that can cause bronchoconstriction and airway hyperresponsiveness in selected human subjects and animals. The mechanism by which PAF induces these changes is not clearly understood. We therefore studied the effects of intratracheal instillation of PAF (30 micrograms/kg) on airway resistance and airway responsiveness in allergic sheep (n = 7) and attempted to modulate these effects with the specific PAF antagonist, WEB-2086, and the antiasthmatic agent, nedocromil sodium (NED). Specific lung resistance (SRL) was measured to assess bronchial responses to PAF, and airway responsiveness was determined by deriving a provocative dose of carbachol in breath units causing an increase in SRL to 4 L times centimeters of H2O per liters per second (PD4) from carbachol dose-response curves. PAF instillation increased mean +/- SD SRL to 228 +/- 134% above baseline. Two to 4 hours after PAF instillation, PD4 decreased by 55 +/- 9% from a baseline of 39 +/- 9 breath units (p less than 0.05). Airway responsiveness remained increased at 24 hours but returned to baseline by 48 hours. Pretreatment with WEB-2086 (3 mg/kg, intravenously) or NED (1 mg/kg, nebulized) blocked (p less than 0.05) PAF-induced bronchoconstriction and PAF-induced airway hyperresponsiveness. Instillation of lyso-PAF (30 micrograms/kg) did not cause bronchoconstriction or airway hyperresponsiveness. Thus, instilled PAF causes bronchoconstriction and airway hyperresponsiveness in allergic sheep by a receptor-mediated mechanism that likely involves the release of secondary mediators, the latter process being sensitive to NED.

Dengue hemorrhagic fever in Cuba, 1981: a retrospective seroepidemiologic study

In Cuba, 2 epidemics of dengue virus occurred: 1 caused by DEN-1 in 1977 and 1 caused by DEN-2 in 1981. The latter was associated with cases of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). To study viral risk factors for DHF/DSS, a retrospective seroepidemiological survey was conducted in Cerro, a densely populated district in Havana City. The prevalence of plaque reduction neutralizing antibodies to DEN-1 and DEN-2 viruses was measured in 1,295 individuals (children and adults). Of these, 43.7% were immune to DEN-1 virus and 23.6% to DEN-2 virus. Of those individuals who were immune, 26.1% were immune to DEN-1 virus only, 6% to DEN-2 virus only, and 17.6% to both viruses. The DEN-2 virus infection rate in DEN-1 immune individuals was 3.8 times higher than in non-immune individuals. The 5 DHF/DSS cases in the sample had evidence of DEN-1 virus plus DEN-2 virus infections. Three were children and 2 were young adults. No cases were found in individuals infected with DEN-1 virus or DEN-2 virus only. Children infected by DEN-1 virus followed by DEN-2 virus had a high risk of acquiring DHF/DSS. Blacks and whites were equally infected with DEN-1 and DEN-2 viruses.

Further analysis on the structural proteins of infectious pancreatic necrosis virus

The structural proteins of infectious pancreatic necrosis virus (IPNV) have been analyzed. Two-dimensional gel electrophoresis showed that IPNV proteins are slightly acidic with apparent pIs ranging from 5.8 to 6.6. To identify the IPNV surface-located proteins, purified virus was labelled either with fluorescein isothiocyanate (FITC) or with Na 125I. After analysis by SDS-PAGE, only the major viral protein, VP2, was labelled by either procedure. The accessibility of VP2 to these reagents suggests that this protein is externally located. In addition, using Concanavalin A conjugated with FITC and IPNV labelling with 3H-mannose, evidence is present that VP2 contains carbohydrate residues.

Methotrexate-induced pneumonitis: appearance four weeks after discontinuation of treatment

A 71-year-old man with a long-standing history of rheumatoid arthritis required methotrexate treatment since 1986, with a total dose of 210 mg. In April 1987, before arthroplastic surgery, methotrexate was discontinued. Four weeks later a syndrome of fever, dry cough, shortness of breath, and diffuse air-space consolidations on the chest radiograph evolved. An antibiotic therapy had no beneficial effect, and a bronchoscopy yielded no pathogens. An open lung biopsy led to the diagnosis of methotrexate-induced pneumonitis. This is the first report of a case where methotrexate-induced pneumonitis developed several weeks after cessation of the treatment. Methotrexate can cause four types of pulmonary adverse reactions: pneumonitis, pulmonary edema, pulmonary fibrosis, and pleuritis. Possible pathogenetic mechanisms, symptoms, treatment, and prognosis are discussed.

[Retrospective sero-epidemiologic survey on dengue virus in the municipalities of Cienfuegos and Palmira]

A retrospective seroepidemiologic survey is made in the municipalities of Cienfuegos and Palmira to determine the presence of neutralizing antibodies to Den-1 and -2 virus in the population. It was found that 21.4% of the population studied had antibodies to Den-1, 12.3% to Den-2, and that 5.5% had been infected by the two serotypes (secondary infection). It became apparent that in the Palmira municipality the percentage of infection due to Den-1 was higher and it was found that in 1980-1981 there was a late dengue (Den-1) outbreak. Therefore, this municipality was probably the only in the country with 2 epidemic outbreaks due to two dengue serotypes (1 and 2) in a 6 month interval. The potential relationship between this fact and the high lethality of hemorrhagic dengue fever in this municipality is established. The influence of environmental, social, and sanitary factors on the risk of infection is suggested. It was found that Whites and Blacks are equally infected and that infection is not a random phenomenon, instead it is favored by the presence of vectors in and around the housing.

[Rapid diagnosis of cytomegalovirus in immunocompromised patients using monoclonal antibodies that detect early viral antigens]

A technique was applied to detect early fluorescent antigens (DEFA) of cytomegalovirus (CMV) using the E13 monoclonal antibodies in 52 immuno-compromised patients hospitalized in the Nephrology Institute of Havana. Of the 75 urine or blood (buffy coat) samples taken, 15 were found positive to CMV. Using classical diploid human fibroblast isolation technique, 12 CMV strains were isolation of previously detected positive samples by DEFA. In addition, CMV was isolated from one sample reported to be negative by DEFA. A coincidence of 80% was found between both techniques. With the ELISA test, all the sample studied have IgG antibodies to CMV.

In vivo and in vitro studies on cold-induced airway response in normal and sensitized rabbits

We measured the changes in lung resistance (RL) induced by cool inspired air under dry air conditions in anesthetized, paralyzed and artificially ventilated rabbits. We compared the airway response to cold air in non-sensitized (NS) animals with the response in rabbits sensitized (S) to bovine serum albumin. Using in vitro tracheal preparations from the same animals, we observed the effects of lowering the bath temperature on smooth muscle tension and also the response to acetylcholine (Ach). Dose-response curves to Ach were constructed and analyzed in terms of maximal contraction (delta Tmax) and pD2 coefficient (negative logarithm of the molar concentration of Ach producing 50% of maximum contraction). The magnitude of cold induced airway response tested in vivo was significantly greater in S (delta RL = +52% +/- 2) than in NS rabbits (+30% +/- 4; P less than 0.01). In vitro the decrease of temperature in the bathing medium induced a significant relaxation of tracheal spirals in both NS and S preparations (delta T = -2.42 +/- 0.34 g/mg wet tissue, -3.36 +/- 0.8 g/mg wet tissue, respectively). However, an adaptation of this response occurred after 8 min in NS rabbits whereas relaxation persisted in S rabbits. The tracheal contractile response to Ach was decreased by bath cooling in S ans NS animals (delta Tmax = 5.53 +/- 0.15 g/mg wet tissue and 5.03 +/- 0.27 g/mg wet tissue at 37 degrees C; 3.05 +/- 0.30 g/mg wet tissue and 1.93 +/- 0.35 g/mg wet tissue at 17 degrees C, respectively). Moreover, cooling also reduced the velocity of response. In all cases, S preparations displayed hyperresponsiveness to Ach and this was observed for maximal changes in tension as well as for pD2 values. Present observations show that cold induces different effects on airway smooth muscle with the production of a contractile response in in vivo preparations but relaxes isolated tracheal spirals. They also suggest that sensitization by foreign proteins may modify the intrinsic properties of tracheal smooth muscle.

Cholinergic responsiveness of respiratory and vascular tissues in two different rat strains

The airway and systemic arterial smooth muscle responsiveness to cholinergic agents of two strains of rats, Rat Albino (RA) and Brown Norway (BN), was compared in vivo and in vitro. In vivo, we measured the doses of carbachol that induced a 100% increase in lung resistance (PD100 RL), a 50% decrease in dynamic lung compliance (PD50 Cdyn), and the value of systolic blood pressure at the carbachol dose of 10 micrograms (Pa 10 micrograms). In vitro airway smooth muscle and systemic arterial smooth muscle responsiveness was assessed by measuring the maximal response to acetylcholine, the slope of the linear portion of the dose-response curve, and the negative logarithm of the molar concentration of acetylcholine producing 50% of the maximal response (pD2). PD100 and PD50 were about four times greater in BN rats than in RA rats. In contrast, Pa 10 micrograms was 1.5 lower in the BN rats. These differences persisted after bivagotomy. Tracheal pD2 was 25% greater in the RA than in the BN strain. The mean dose-response curve of parenchymal strips of RA rats was situated upward and to the left of the BN curve, but the reverse was observed for aortic smooth muscle dose-response curves. Thus 1) airway smooth muscle responsiveness to cholinergic agents is greater in RA strain than in BN, but the reverse is true for systemic arterial smooth muscle responsiveness; and 2) these differences are not due to factors extrinsic to the smooth muscle, since they occurred in vitro and may depend on different densities of muscarinic receptors.

Infection of a poikilothermic cell line (XL-2) with eastern equine encephalitis and western equine encephalitis viruses

Eastern Equine Encephalitis (EEE) was in Cuba before the 1940s; the virus has been isolated from horses, birds, and rodents during epizootic as well as interepizootic periods. The only isolation of Western Equine Encephalitis (WEE) virus was from a sick pigeon found in the vicinity of Havana University. Both viruses can cause human disease; the isolation of WEE virus from the centre of an urban area emphasises the need for the prompt isolation and rapid identification of these agents. The object of this work was to compare the sensitivity of a continuous cell line (XL-2) from the toad, Xenopus laevis, with primary chick embryo cell cultures (CEC) routinely used for isolation as well as assay of these viruses. Both cell systems were infected with EEE virus isolated from horse brain and WEE virus isolated from a sick pigeon. A clear cytopathic effect (CPE) consisting of rounding and detachment of cells was observed in both cell cultures infected with the two viruses. By 18 hours post-infection, there was partial destruction of the cell monolayer and by 24 hours the CPE was total. The infectious titre of EEE and WEE viruses in XL-2 and CEC were similar. Both viruses produced small plaques (0.5-1.0 mm diameter) in XL-2 cells. Studies on the sensitivity of the XL-2 cells for direct isolation of the two viruses from field samples and for the detection of Cuban flaviviruses by the immunofluorescence test are in progress.

Analysis of cell structural and functional diversity by combination of micromanipulation and microfluorimetry

Fluorescent molecules are widely used to study quantitative cell properties, such as density of different antigenic markers or membrane responses to various stimuli. In most cases, studies are done on bulk cell populations with a spectrofluorimeter or at the single cell level with a cytofluorograph. However, only microspectrofluorimetric techniques allow continuous recording of dynamic events undergone by individual cells. The aim of the present report was twofold: first, to describe a methodology easily accessible to cell biologists that allows simultaneous manipulation of single cells and measurements of their fluorescence properties; and second, through this methodology to study quantitative aspects of cell structure and function such as binding of a fluorescein-labeled lectin, transfer of fluorescent molecules between labeled and unlabeled cells brought in close contact, or fluorescence response of individual cells stimulated after being loaded with a potential-sensitive dye. We conclude that the understanding of many aspects of cell structure and behavior requires that individual cells be studied under dynamic conditions and for prolonged periods of time.

Visceral involvement of dialysis amyloidosis

Carpal tunnel syndrome, peripheral arthropathy, erosive spondyloarthropathy and lytic bone lesions have all been associated with dialysis amyloidosis. Recent studies indicate that beta 2-microglobulin is the major constituent protein in this new form of amyloidosis. Dialysis amyloidosis was reported to have a local rather than a systemic involvement, although its full extent is yet to be determined. We investigated 3 patients on maintenance hemodialysis with bilateral carpal tunnel syndrome and amyloid arthropathy and found amyloid depositions in several organs. These findings suggest that, in contrast to what had been thought previously, dialysis amyloidosis could have systemic as well as visceral distribution. The amyloid deposits found were resistant against potassium permanganate treatment and reacted with anti-human beta 2-microglobulin antibody.

Identity between infectious pancreatic necrosis virus VR-299 and a Chilean isolate

Nucleic acid and protein electrophoretic analyses of the Chilean isolate of infectious pancreatic necrosis virus showed that genomic RNA, as well as the major proteins, were indistinguishable from those of the VR-299 serotype. The data are in good agreement with the theory that the virus was introduced into Chile from North America.

Dengue haemorrhagic fever in Cuba. II. Clinical investigations

Clinical and serological studies were carried out on 114 patients admitted to hospital in Havana, Cuba with Dengue Haemorrhagic Fever and Dengue Shock Syndrome (DHF/DSS). Serological confirmation of dengue was obtained in 90% of cases, with 5% of cases primary and 95% secondary. Fever, haemorrhagic manifestations, vomiting and headache were the most frequent signs and symptoms. Among haemorrhagic manifestations, petechiae and vaginal bleeding were reported in a larger number of patients. 21 patients presented shock and, of these, 20 were secondary infections. The disease appeared more frequently in white persons and in women. The aetiopathogenicity of the syndromes is discussed. 95% of the cases could be explained on the basis of the secondary infection hypothesis.

Dengue haemorrhagic fever in Cuba. I. Serological confirmation of clinical diagnosis

Serological studies by the haemagglutinin inhibition test to confirm a clinical diagnosis of dengue were done on 406 patients during the dengue 2 epidemic in Cuba in 1981. 49% of the cases were serologically positive; of these 64% was classified as primary and 36% as secondary. The frequency of symptoms is described: the most frequent were fever, headache, malaise and vomiting. Haemorrhagic manifestations predominated significantly in the secondary cases. The white race and female sex were found to predominate in the positive cases.

Retention of pollen grains in human lung

The possibility of the penetration of pollen grains into the tracheobronchial tree is still a controversial question. To investigate this phenomenon further two different approaches were conducted: 1) Acetolysis (acidic degradation of organic constituents) of mucosal samples from different levels of the pig respiratory tract showed that specific (plane tree) inhaled pollens were not found beyond the main bronchi. 2) In contrast, a noticeable number of pollens were present in acetolyzed residues of lung surgical samples; this was shown to be due to contamination. In the first approach this problem was avoided; however, the analysis of surgical samples could be a valuable technique if suitable controls were included.

Pollen-allergen IgE response in the inbred rat. Regulation of allergen P-IgE antibodies in high and low responders by suppressive factors

Cyclophosphamide treatment (100 mg/kg) significantly increased the IgE response to plane-tree allergen P in low-responder strains of rats. A suppressive serum was obtained by injection of CFA in normal low-responder strains. The injection of this serum 2 days after cyclophosphamide treatment and 1 day prior to primary immunization, reversed the cyclophosphamide-enhanced IgE antibodies response without affecting the IgG2a levels. This effect is strain specific.