Side-grooved Charpy impact testing: Assessment of splitting and fracture properties of high-toughness plate steels.

The fracture properties and susceptibility to crack-divider delamination (or splitting) of three commercially produced high-toughness X70 pipeline steels are evaluated with Charpy impact test samples modified to incorporate side grooves. Temperature-dependent impact data are compared with standard Charpy V-notch (CVN) and drop weight tear test data (DWTT). It is shown that the modified geometry prevents the accumulation of plastic deformation at upper shelf energy temperatures and improves the accuracy of impact properties measurements. It also promotes splitting, mirroring the splitting behavior assessed with DWTT samples. To demonstrate the effects of splitting on fracture characteristics and impact energies, steels with similar tensile properties but different splitting susceptibilities are considered. Splitting severity is maximum close to the ductile-brittle transition temperature. However, the effect of splitting on impact energy is minimum at such temperature, as this type of delamination increases energy absorption at lower temperatures and decreases it by a similar extent at higher temperatures. This finding is discussed by examination of force-displacement curves from the instrumented impact tests.

Suppression of T cell-mediated cutaneous basophil hypersensitivity by serum from guinea pigs immunized with mycobacterial adjuvant.

Guinea pigs immunized with protein antigens emulsified with complete Freund's adjuvant (CFA) and skin tested at 3-4 wk have classical tuberculin-type delayed hypersensitivity (DH) reactions with few basophils present. However, recipients of T cells from these animals have delayed responses containing large basophil infiltrates and thus resemble basophil-rich cutaneous basophil hypersensitivity (CBH) responses that are elicited in animals immunized without CFA. This suggests that animals immunized with CFA have T cells with basophil-recruiting capacity but that this activity is suppressed. Using a transfer system, we found that immune serum from donors immunized with CFA had the ability to suppress the basophil-recruiting capacity of immune T cells. When immune serum and peritoneal exudate cells from guinea pigs immunized with CFA were co-transferred intravenously to normal recipients, the cell-mediated transfer of basophil-rich responses was suppressed. The responsible serum factor was antigen nonspecific, had an approximately 70,000 mol wt, and acted preferentially on cells from donors that express basophil-poor DH responses. Thus, tuberculin-type delayed hypersensitivity and CBH might be mediated by a common T cell, but the resulting basophil component of the delayed response depends on the modulation of T cell recruitment of basophils by factors in CFA-immune serum.

Ability of an oral formulation of afoxolaner to protect dogs from Borrelia burgdorferi infection transmitted by wild Ixodes scapularis ticks.

A randomized, blinded, negative controlled study was conducted to determine whether treatment with afoxolaner (NexGard®, Merial, Inc.) would prevent the transmission of Borrelia burgdorferi to dogs by wild caught Ixodes scapularis ticks. Twenty healthy dogs were randomly assigned to two groups of ten dogs each. Ten dogs were treated orally on Day 0 at a dose near the minimum recommended dose of afoxolaner of 2.5mg/kg (actual doses 2.5-3.1mg/kg) and ten control dogs were not treated. On Day 28, each dog was infested with approximately 50 adult unfed wild caught I. scapularis that had a 67% B. burgdorferi infection rate (determined by polymerase chain reaction). On Day 33, live ticks were counted and removed. No ticks were found on treated dogs while control dogs had an average of 21.4 ticks. To detect infection, the B. burgdorferi-specific C6 antibody SNAP® 4Dx® test (IDEXX) was performed on serum collected before infestation (all dogs seronegative on Days -6 and 27) and on Days 48, 63, 77 and 92. The ten treated dogs remained seronegative through the end of the study (Day 92), while nine out of the ten control dogs were infected, as demonstrated by their seroconversion to being positive for the presence of the B. burgdorferi-specific C6 antibody starting on Day 48. In this study, all dogs treated with NexGard® 28days prior to challenge with wild caught I. scapularis ticks were protected from B. burgdorferi infection, while nine out of the ten untreated control dogs were infected.

Cutaneous basophil hypersensitivity to inhalant allergens in atopic dermatitis patients: elicitation of delayed responses containing basophils following local transfer of immune serum but not IgE antibody.

Inhalant allergens applied to the skin of sensitive atopic dermatitis patients by means of a modified patch test technique, induce acute eczematous lesions. These lesions contain basophils, eosinophils, mononuclear cells, and neutrophils and represent an example of human cutaneous basophil hypersensitivity. The role of IgE antibody in this eczematous reaction was studied by systemic and local passive transfer experiments. Plasma with high IgE antibody when infused into patients with hypogammaglobulinemia as part of their replacement treatment resulted, post infusion, in cutaneous mast cell and blood basophil sensitization as measured by quantitative skin testing and leukocyte histamine release. Subsequent patch tests on these patients using the house dust mite antigen, antigen P1, produced macroscopic erythematous responses containing mononuclear cells, and eosinophils but not basophils. Local transfer of atopic dermatitis serum with high IgE antibody produced weak macroscopic responses and in these lesions mononuclear cells and both basophils and eosinophils were present. The serum activity which allowed transfer of basophil and eosinophil recruitment was heat labile. Specifically purified antibody to the mite antigen P1 (containing IgE and IgG antibody), when transferred, allowed eosinophil but not basophil recruitment to patch test sites. These results suggest that while the allergen-induced patch test response may involve IgE antibodies, as well as the cells normally involved in delayed responses, another serum activity is also involved.

Sarcoidosis: in search of Kveim reactivity in vitro.

Granuloma formation in patients with sarcoidosis may be evoked by the intradermal injection of homogenised sarcoid tissue (the Kveim reaction). Attempts to demonstrate an in vitro counterpart of the reaction have been unsuccessful. The cytokine interleukin-2 (IL-2) enhances immune responses in vivo and in vitro. We report here an attempt to amplify the Kveim reaction by the addition of IL-2. We studied the effect of Kveim reagent on the proliferative responses of peripheral blood mononuclear cells (PBMC) in the presence or absence of exogenous IL-2. Twenty-eight patients were studied and 14 healthy subjects served as controls. PBMC were cultured, in vitro, in the presence of Kveim reagent. Recombinant IL-2 or both of these combined. Proliferative responses were measured by [3H]-thymidine incorporation. The response of patients' PBMC in the presence of Kveim reagent at a dilution of 1:40 was significantly below the unstimulated response (P less than 0.01). Kveim reagent at a dilution of 1:40 also inhibited the proliferative response of patients PBMC to IL-2 (P less than 0.005); greater dilutions (1:100 and 1:1000) of Kveim reagent were not inhibitory. Responses of PBMC from control subjects (both unstimulated and IL-2 generated) were reduced in the presence of Kveim reagent, however, these reductions were not statistically significant.

Home environment and childhood asthma.

The prevalence of childhood asthma has increased dramatically in the past 20 years. The reasons for the increase are unclear but many authors suggest that changes in the home environment favourable to proliferation of the house dust mite are to blame. Our study aimed to compare home environment of children with asthma and controls. A questionnaire on home environment was administered to the parents of 134 children with asthma and 118 controls. Detailed studies of home temperature, humidity and dust mite allergen (DERp1) levels were performed in 20 homes (10 from each group). The questionnaire response rate was 86%. There were no significant differences between asthma and control homes with respect to social class, type of housing, smoking habits, pets, insulation, home heating, bedding, carpeting and domestic cleaning habits. A first degree family history of atopy was obtained in 42% of asthmatic families and in 16% of controls. Temperature, humidity and dust mite allergen levels were similar in both groups. The majority gave readings exceeding recommended norms. Values for DERp1 were above thresholds by a factor of 5 in 48%. Home environment does not significantly differ in children with or without asthma. The home environment is now generally mite friendly, and large segments of the childhood population are now exposed to high levels of DERp1. This may account for the increasing prevalence as more and more children with an atopic background develop overt symptoms in response to high levels of allergen load.

Difficulties in differentiating Neisseria cinerea from Neisseria gonorrhoeae in rapid systems used for identifying pathogenic Neisseria species.

Neisseria cinerea and Neisseria gonorrhoeae may occur at the same body sites and may have similar colony morphologies. Ideally, systems used for rapid identification of N. gonorrhoeae should be able to differentiate N. cinerea from gonococci. We tested seven N. cinerea strains using the Gonochek II (Du Pont Diagnostics), Minitek (BBL Microbiology Systems), RapID-NH (Innovative Diagnostics, Inc.), RIM-N (American Microscan), and Phadebact (Pharmacia Diagnostics) systems. We found that the reactions produced by N. cinerea in Gonochek II, Minitek, and RapID-NH kits could be confused with the results produced by some strains of N. gonorrhoeae. The susceptibility of N. cinerea to colistin, its ability to grow on tryptic soy or Mueller-Hinton agar, and its inability to grow on modified Thayer-Martin medium help differentiate it from gonococci.

Basophils in human disease.

Hypersensitivity reactions containing significant infiltrates of basophils occur in a large proportion of allergic diseases such as contact dermatitis, atopic dermatitis, and allergic rhinitis, and are quite deleterious. However, the potential usefulness of such responses can be recognized in similar reactions in guinea pigs responding to tissue invasion by complex multicellular parasites in which interactions occur between thymic-derived T lymphocytes, antibodies, and basophils in immune resistance responses. Perhaps inappropriate and deleterious allergic responses to pollens, chemicals, and insects is the price that we must pay for the ability to reject complex parasites.

Assessment of skin reactivity and specific antibody to egg and milk proteins in patients with atopic dermatitis: comparison with responses to the house dust mite antigen.

Sixty patients with atopic dermatitis attending an allergy clinic were assessed for evidence of skin sensitivity and serum antibodies to egg and milk proteins. Prick skin test responses to egg were found in 23 patients and in 74% of these positive egg radioallergosorbent test (RAST) was demonstrable. Positive prick test for milk were present in 10 patients, but only 30% gave a positive milk RAST. Quantitative intradermal skin testing, RAST, and a double antibody antigen binding radioimmunoassay confirmed the presence of IgE antibody to egg proteins but indicated that the levels were very low when compared to those seen to the house dust mite antigen in sensitive patients. In contrast, IgG antibody to purified egg and milk proteins was present in large amount in most patients, the levels being significantly higher than in non-allergic controls.

Parental smoking, breast feeding, and respiratory infection in development of allergic diseases.

Environmental factors were examined as determinants of clinical disease in a five year prospective study of 73 children born to atopic parents. Clinical follow up for evidence of eczema and wheezing was combined with regular skin testing, immunoglobulin assay, and respiratory viral culture where appropriate. Thirty six children developed eczema, which was often associated with a positive result of a skin test to ingestants in the first year and inhalants by the fifth year. Thirty two children developed one or more episodes of wheeze. Fifteen children wheezed once only, and not all of these developed atopy. No pattern of respiratory infection in early life was characteristic of children with recurrent wheeze. There was a significant difference in parental smoking habits between children with and without episodes of wheeze at the fifth birthday. No protective effect of breast feeding could be shown. The development of allergic disease in susceptible children is influenced by many environmental factors. Advice to families about reduction of environmental allergens continues to pose problems, but parents should be advised to avoid smoking in the child's presence.

IgG1 antibody-dependent mediator release after passive systemic sensitization of basophils arriving at cutaneous basophil hypersensitivity reactions.

When antigen is injected into a 24-hr cutaneous basophil hypersensitivity (CBH) reaction of an actively sensitized guinea pig, local basophils degranulate and release histamine. This reaction is called cutaneous basophil anaphylaxis and may be antibody mediated. We now report passive sensitization of basophils at CBH sites by systemic transfer of anti-picryl immune serum. Keyhole limpet hemocyanin- (KLH) immunized animals were skin tested with KLH to elicit 24-hr CBH reactions at day 7. Anti-picryl serum was injected i.v. at various times. On day 7, blue dye was injected i.v., and then 24-hr CBH sites vs nearby normal skin were challenged with 0.1 microgram picryl-human serum albumin (Pic-HSA). An immediate increase in vascular permeability (blueing) was noted at normal skin sites due to systemic passive cutaneous anaphylaxis (PCA), and augmented blueing occurred at CBH sites compared with normal skin. Systemic passive sensitization of CBH sites occurred when antiserum was administered as little as 1 hr before challenge of CBH site. However, local administration of anti-picryl serum (as in a local PCA reaction) was not able to sensitize tissue basophils, whether antigen was administered locally or systemically. The serum factor that mediated cutaneous basophil anaphylaxis was heat-stable (56 degrees C X 4 hr) 7S IgG1 antibody. Electron microscopy of Pic-HSA-challenged CBH sites in animals that received IgG1 antibody showed that local basophils undergo anaphylactic degranulation by exocytosis. These studies suggest that basophils arriving at CBH reactions are sensitized for anaphylactic function by antibody that can be acquired in the circulation, but possibly not at the local site.

Defective cell mediated immunity in sarcoidosis: effect of interleukin-2.

Interleukin-2 has been reported to enhance the immune response in diseases characterised by defective cell mediated immunity. The effect of exogenous recombinant interleukin-2 was studied on the proliferative and cytotoxic responses of peripheral blood mononuclear cells from 39 patients with sarcoidosis and 14 healthy control subjects. The proliferative response to purified protein derivative was smaller in patients than in control subjects (p less than 0.001) whereas the response to 80 U interleukin-2 alone and to purified protein derivative and interleukin-2 did not differ significantly between the two groups. In addition, in eight patients but no control subjects tritiated thymidine incorporation induced by the combination of purified protein derivative and interleukin-2 was more than twice the sum of that induced by purified protein derivative and interleukin separately. Cytotoxic activity occurring spontaneously and induced by purified protein derivative and interleukin-2 in blood mononuclear cells was significantly less for patients with sarcoidosis than for control subjects (p less than 0.05 spontaneous, less than 0.001 purified protein derivative induced, less than 0.02 interleukin induced). Synergism between antigen and interleukin did not occur with respect to the cytotoxic response in either patients or controls. Defective interleukin-2 production may contribute to, but does not entirely explain, the functional abnormalities of peripheral blood lymphocytes from patients with sarcoidosis.

Production of 14C-labeled gas in BACTEC Neisseria Differentiation kits by Neisseria cinerea.

Six strains of Neisseria cinerea were tested in BACTEC Neisseria Differentiation kits (Johnston Laboratories, Inc., Towson, Md.), and all yielded positive glucose growth indices and negative maltose and fructose growth indices. These results were similar to those achieved with Neisseria gonorrhoeae. However, most of the N. cinerea isolates tested yielded 3-h glucose growth indices that were lower than those obtained with gonococci. 14C-labeled gas was produced significantly faster (P less than 0.02) by N. gonorrhoeae than by N. cinerea. Additional studies suggested that the 14C-labeled gas produced by N. cinerea was carbon dioxide. N. cinerea strains were similar to Branhamella catarrhalis strains because both species failed to produce detectable acid from glucose, maltose, sucrose, fructose, and lactose in cysteine-tryptic agar media. However, in contrast to N. cinerea strains, B. catarrhalis strains did not metabolize glucose in BACTEC Neisseria Differentiation kits.

Nosocomial pneumonia caused by a glucose-metabolizing strain of Neisseria cinerea.

We describe what appears to be the first reported case of nosocomial pneumonia caused by Neisseria cinerea. The isolate metabolized glucose when tested in BACTEC Neisseria Differentiation Kits (Johnston Laboratories), but did not produce detectable acid in cystine-Trypticase (BBL Microbiology Systems) agar medium or in modified oxidation-fermentation medium. Clinical laboratories that rely on the BACTEC method for differentiation of pathogenic neisseriae should be aware of the fact that N. cinerea may mimic N. gonorrhoeae when tested in BACTEC Neisseria Differentiation kits. The ability of N. cinerea to grow well on tryptic soy and Mueller-Hinton agars and its inability to grow on modified Thayer-Martin medium are characteristics which help to distinguish N. cinerea from N. gonorrhoeae.

Development of IgE and IgG antibodies to food and inhalant allergens in children at risk of allergic disease.

In a prospective study of 92 children with at least one atopic parent, the development of the specific antibody responses to food and inhalant allergens during the first 5 years of life were assessed. By the radioallergosorbent test egg specific IgE antibody occurred in about 30% of the children with the mean peak concentration at 12 months. By the second year the prevalence of this antibody had increased whereas the mean concentration had decreased. Milk specific IgE antibody could not be shown in any subject, including four whose skin tests yielded positive results. Food specific IgG antibody was noted by antigen binding radioimmunoassays at 3 months in most children. These responses had peaked and began to fall by the fifth year. In contrast few children had detectable IgE or IgG antibody to inhalant allergens before the first 2 years of life. Both the concentration and prevalence of specific antibody, however, increased from the second to the fifth year and was greater in children whose skin tests yielded positive results. Breast feeding was associated with an increase in the prevalence of positive results from skin tests but was not associated with detectable IgE antibody to both food proteins, a lower concentration of IgG antibody to cows' milk, and was not associated with protection against the development of disease. A high level of exposure to dust mite was associated with an increased prevalence of positive results from skin tests to dust mite and appreciably higher antibody concentration. This study indicates differences in the humoral responses to food and inhalant allergens. Environmental factors appear to influence the development of these responses.

Reduction of house dust mite allergen levels in the home: use of the acaricide, pirimiphos methyl.

House dust mite sensitivity is very common in patients with bronchial asthma, yet dust mite avoidance frequently receives little attention in clinical management. It is likely that any reduction in allergen levels associated with routine cleaning is insufficient to allow clinical improvement. In the present study the acaricide pirimiphos methyl is shown to reduce the levels of Dermatophagoides pteronyssinus, antigen P1 in homes. Following a single application the level of antigen P1 in dust from carpets was reduced by up to 73% and by more than 50% in soft furnishings. Serial sampling showed a reduction for 6 weeks under conditions where carpets and chairs treated with solvent showed a progressive rise in allergen level. Furthermore the survival of mites in cultures or infested carpet segments was markedly inhibited, with antigen P1 accumulation reduced by greater than 90%. These results suggest major reductions in house dust mite allergen levels in the home can be achieved.

House dust mite allergen levels and an anti-mite mattress spray (natamycin) in the treatment of childhood asthma.

Natamycin, a fungicide marketed as Tymasil, is claimed to reduce house dust mite numbers and would therefore be expected to improve asthma in children with mite sensitivity. We have tested this assertion by a double-blind, placebo-controlled trial. There was no significant effect on levels of Der p I in mattress dust between active and placebo groups at the end of the spraying period. Histamine inhalation challenge PC20, clinic visit symptom scores and lung function tests reflecting either large or small airways obstruction were also unchanged. Therefore this product is not a therapeutic option for mite-allergic patients using the manufacturer's recommended dose and method of administration. Other factors influencing the Der p I levels were also investigated. Of these, only month of measurement and bedroom wall humidity showed any association.

Increase in skin mast cells following chronic house dust mite exposure.

Application of inhalant allergens in high concentration to the mildly abraded skin of sensitive patients with atopic dermatitis gave rise to eczematous skin responses at 48 h. These lesions, infiltrated by basophils, eosinophils and mononuclear cells, are examples of cutaneous basophil hypersensitivity. Repeated application of allergen induced an increase in skin mast cells by 6 days, the mast cell hyperplasia replacing the earlier basophil infiltration. No electron microscopic evidence of mast cell heterogeneity among the recruited cells was found.