A comparison of objective and subjective measures of cough in asthma

BACKGROUND

Cough is widely recognized as a key symptom in the diagnosis and the monitoring of asthma, but little is known about how best to assess cough in asthma.

OBJECTIVE

To determine how objective cough rates correlate with subjective measures of cough in asthma.

METHODS

We studied 56 subjects, median age 42.0 years (range, 28.5-71), 34 (60.7%) female, with asthma. Subjects performed cough reflex sensitivity testing (concentration of citric acid causing 2 and 5 coughs [C2 and C5]), 24-hour fully ambulatory cough recordings, subjectively scored the severity of their cough (visual analog scales and 0-5 score) and completed a cough-related quality of life questionnaire (Leicester Cough Questionnaire). Ambulatory cough recordings were manually counted and reported in cough seconds per hour (cs/h).

RESULTS

The median time spent coughing was 2.6 cs/h (range, 0.0-14.2), with subjects spending more time coughing by day (median, 3.9 cs/h [0.0-18.5]) than by night (median, 0.3 cs/h [0.0-8.7]; P < .001). A weak inverse relationship was seen between day cough rates and log(10)C2 (r = -0.39; P = .03) but not log(10)C5 (r = -0.08; P = .65). Objective time spent coughing was also weak-moderately associated with subjective cough scores and visual analog scales, and most strongly correlated with cough-related quality of life (r = -0.54; P < .001).

CONCLUSION

Subjective measures of cough and cough reflex sensitivity are poor surrogates for objective cough frequency in asthma. When designing studies to assess interventions for cough in asthma, we advocate a combination of both objective measures of cough and cough-related quality of life.

Residual and contact herbicide transport through field lysimeters via preferential flow

Usage of glyphosate [N-(phosphonomethyl)-glycine] and glufosinate [2-amino-4-(hydroxy-methylphosphinyl)butanoic acid] may reduce the environmental impact of agriculture because they are more strongly sorbed to soil and may be less toxic than many of the residual herbicides they replace. Preferential flow complicates the picture, because due to this process, even strongly sorbed chemicals can move quickly to ground water. Therefore, four monolith lysimeters (8.1 m(2) by 2.4 m deep) were used to investigate leaching of contact and residual herbicides under a worst-case scenario. Glufosinate, atrazine (6-chloro-N(2)-ethyl-N(4)-isopropyl-1,3,5-triazine-2,4-diamine), alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl) acetamide], and linuron (3-3,4-dichlorophenyl-1-methoxy-1-methylurea) were applied in 1999 before corn (Zea mays L.) planting and glyphosate, alachlor, and metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] were applied in 2000 before soybean [Glycine max (L.) Merr.] planting. A high-intensity rainfall was applied shortly after herbicide application both years. Most alachlor, metribuzin, atrazine, and linuron losses occurred within 1.1 d of rainfall initiation and the peak concentration of the herbicides coincided (within 0.1 d of rainfall initiation in 2000). More of the applied metribuzin leached compared with alachlor during the first 1.1 d after rainfall initiation (2.2% vs. 0.035%, P < 0.05). In 1999, 10 of 24 discrete samples contained atrazine above the maximum contaminant level (atrazine maximum contaminant level [MCL] = 3 mug L(-1)) while only one discrete sample contained glufosinate (19 mug L(-1), estimated MCL = 150 mug L(-1)). The results indicate that because of preferential flow, the breakthrough time of herbicides was independent of their sorptive properties but the transport amount was dependent on the herbicide properties. Even with preferential flow, glyphosate and glufosinate were not transported to 2.4 m at concentrations approaching environmental concern.

Regulation of CD2-mediated heterotypic interactions of murine T lymphocytes

In this study we have investigated the expression and function of the murine CD2 receptor in T cells. The surface level of CD2 increased between 300 and 400% when T cells were activated, which also induced a rapid increase of nearly 40-fold in the steady-state levels of CD2 mRNA. Although the activated lymphocytes were found to internalize and degrade nearly 50% of membrane-bound CD2, in addition to shedding the CD2 receptor from the cell surface, this does not account for the discrepancy between the increase in mRNA and antigen levels during activation. These findings suggest that the expression of CD2 is also regulated by post-transcriptional processes which control the translational efficiency of the CD2 message. Activation of T cells enhanced their interaction with mesenchymal cell targets (fibroblasts) via a CD2-dependent adhesion pathway which was not inhibited by the anti-mouse CD48 (sgp-60) mAb OX78, the only counter-receptor thus far identified on other cells as a ligand for the mouse CD2 receptor. Moreover, since murine fibroblasts were found not to express CD48, our results implicate a novel ligand for CD2, possibly a homologue of the human LFA-3. This new pathway of heterotypic T cell interaction would be facilitated by utilization of the large intracellular pool of CD2 transcripts to up-regulate CD2 expression and, as this receptor is a major signal-transducing molecule, would further enhance T cell activation and increase CD2-mediated adhesion.

Collagen shields impregnated with gentamicin-dexamethasone as a potential drug delivery device

We investigated the ability of collagen shields impregnated with gentamicin sulfate and dexamethasone to deliver medication into rabbit eyes. We compared the aqueous humor gentamicin and dexamethasone levels delivered by collagen shield and subconjunctival injection therapy at five time points over a ten-hour period, by using a fluorescence polarization immunoassay and high-pressure liquid chromatography. Our in vitro studies showed that impregnated collagen shields released most of the gentamicin within the first 30 minutes of elution, whereas dexamethasone was released gradually over a ten-hour period. The collagen shields impregnated with gentamicin and dexamethasone produced aqueous gentamicin levels that were significantly lower (P = .014) than those produced by subconjunctival injection therapy at 30 minutes and that were comparable to subconjunctival injection therapy at the other time points. Minimum inhibitory concentrations of gentamicin (approximately 4 micrograms) were observed in aqueous humor within 30 minutes in rabbits that received subconjunctival injections and at one hour in rabbits treated with impregnated collagen shields. The impregnated collagen shields produced aqueous dexamethasone levels that were significantly lower (P = .004) than those produced by subconjunctival injection therapy at one hour, significantly higher (P = .028) than subconjunctival injection therapy at six hours, and comparable to subconjunctival injection therapy at the other time points. Collagen shield delivery of gentamicin-dexamethasone may be comparable to subconjunctival injections and provide an alternative therapy after intraocular surgery.

Inhibition of 5-lipoxygenase and cyclo-oxygenase in leukocytes by feverfew. Involvement of sesquiterpene lactones and other components

Leaves or infusions of feverfew, Tanacetum parthenium, have long been used as a folk remedy for fever, arthritis and migraine, and derived products are widely available in U.K. health food shops. Previous reports have suggested interactions with arachidonate metabolism. Crude chloroform extracts of fresh feverfew leaves (rich in sesquiterpene lactones) and of commercially available powdered leaves (lactone-free) produced dose-dependent inhibition of the generation of thromboxane B2 (TXB2) and leukotriene B4 (LTB4) by ionophore- and chemoattractant-stimulated rat peritoneal leukocytes and human polymorphonuclear leukocytes. Approximate IC50 values were in the range 5-50 micrograms/mL, and inhibition of TXB2 and LTB4 occurred in parallel. Isolated lactones (parthenolide, epoxyartemorin) treated with cysteine (to neutralize reactive alpha-methylene butyrolactone functions of the sesquiterpenes). Inhibition of eicosanoid generation appeared to be irreversible but not time-dependent. We conclude that feverfew contains a complex mixture of sesquiterpene lactone and non-sesquiterpene lactone inhibitors of eicosanoid synthesis of high potency, and that these biochemical actions may be relevant to the claimed therapeutic actions of the herb.

Simultaneous measurement of cell surface and intracellular antigens by multiple flow cytometry

We have employed a method for permeabilizing lymphocytes with the detergent saponin in order to detect an intracellular protein simultaneously with surface antigens by flow cytometry (FCM). Using monoclonal antibodies specific for the murine CD2 receptor and for the lysosomal enzyme, beta-glucuronidase (Gus), we found that the expression of both of these antigens increased markedly when T cells were activated. Two sensitive methods were used to show that FCM provided an accurate measure of the actual number of CD2 and Gus molecules present in the lymphocytes. Immunogold electron microscopy revealed the precise ultrastructural localization of these different components and corroborated the specificity of the multiple labelling procedure for the simultaneous detection of surface and intracellular antigens. We also developed a three-colour FCM technique which we used to examine the changes in Gus expression in the CD4 and CD8 T cell sub-sets during activation.

Anaphylatoxin levels in human vitreous humor

The complement system is involved not only in host defense against infection but also in autoimmune tissue damage. Using a radioimmunoassay, we sought to measure levels of C3a, C4a and C5a (activated complement fragments with anaphylatoxin functions) in human vitreous humor from eyes with and without vitreal inflammation. Vitreous from 11 patients with clinical evidence of vitritis (Group 2) had significantly higher levels of protein, C3a and C4a and significantly higher ratios of these anaphylatoxins to protein than vitreous from 19 patients without clinical evidence of vitritis (Group 1). The finding that not only the absolute levels of anaphylatoxins but also the ratios of anaphylatoxins to protein were significantly higher in vitreous from Group 2 than vitreous from Group 1 or normal plasma suggested that complement activation was taking place in inflamed vitreous. Because of irreversible binding to leukocytes, C5a is difficult to measure and correlate with complement activation, and we were unable to detect it in any vitreous sample.

Comparison of complement activation by silicone intraocular lenses and polymethylmethacrylate intraocular lenses with polypropylene loops

Silicone intraocular lenses are undergoing clinical investigation for use in the United States. We compared the ability of silicone intraocular lenses to activate the complement system in human sera with that of polymethylmethacrylate intraocular lenses with polypropylene loops using a radioimmunoassay that measures levels of activated complement fragments. Sera incubated with polymethylmethacrylate lenses with polypropylene loops had higher levels of C3a and C5a, but not C4a, than control sera incubated without intraocular lenses. On the other hand, there were no differences in levels of C3a, C4a, and C5a between sera incubated with silicone lenses and control sera. These results suggest that polymethylmethacrylate lenses with polypropylene loops activate the alternative pathway of complement, while silicone lenses do not.

Anaphylatoxin levels in human aqueous humor

Radioimmunoassay was used to measure levels of C3a, C4a, and C5a in aqueous humor from 13 normal eyes, 8 noninflamed eyes with a history of surgery or inflammation, and 14 eyes with anterior uveitis. The authors were unable to measure levels of C3a, C4a, or C5a in normal aqueous humor. In noninflamed aqueous humor from eyes with a history of surgery or inflammation, the authors were unable to measure levels of C4a or C5a, but were able to measure low levels of C3a in 3/8 patients. In aqueous humor from eyes with anterior uveitis, the authors were able to measure levels of C3a in all 14 patients, C4a in 9/14 patients, and C5a in 5/14 patients. Patients with severe anterior uveitis had higher levels of C3a than those with moderate anterior uveitis. The higher ratios of anaphylatoxin to protein levels in inflamed aqueous humor, when compared to normal plasma or noninflamed aqueous humor, suggested that complement was being activated by either the classical or alternative pathways in inflamed aqueous humor. Measurable levels of C3a without detectable C4a in five patients with anterior uveitis suggested alternative pathway activation of complement.

Complement inhibitors in normal cornea and aqueous humor

C1 inhibitor, beta 1H and C3b inactivator are important inhibitory proteins that regulate the complement system. These inhibitor proteins were detected by gel double diffusion in eluates from normal corneas, but not in normal aqueous humor. Functional tests of C1 inhibitor and C3b inactivator showed low-to-absent levels of these inhibitory proteins in normal aqueous humor. On the other hand, the mean activities of C1 inhibitor and C3 inactivator in corneas were nearly as high as those in sera, and there were no statistically significant differences between the values. The lower molecular weights of complement inhibitors, relative to other complement components, may account for their higher levels in normal cornea and may tip the balance in favor of inhibition of complement activation in the noninflamed cornea.

Carcinoids: the association of histologic growth pattern and survival

There are five generally accepted carcinoid histologic growth patterns, i.e., insular, trabecular, glandular, undifferentiated, and mixed. To determine their possible prognostic significance, a panel of pathologists studied the growth patterns of 138 carcinoids collected from an Eastern Cooperative Oncology Group carcinoid advanced stage disease chemotherapy investigation. Survival times were measured from date of initial pathologic diagnosis of carcinoid disease to date of either death or last follow-up. Significant differences were observed in survival times between the five major growth patterns (P less than 0.001). Within the mixed growth pattern group, significant differences in survival time were also observed (P approximately 0.05). In decreasing order of median survival time in years, the growth patterns ranked as follows: mixed insular plus glandular, 4.4; insular, 2.9; trabecular, 2.5; mixed insular plus trabecular, 2.3; three pooled low incidence rate mixed growth patterns, 1.4; glandular, 0.9; and undifferentiated, 0.5. Histologic growth patterns are recommended as a stratification factor in future studies of this disease.