Sequence analysis of cDNA coding for a major house dust mite allergen, Der f I

A cDNA clone coding for Der f I, a major allergen from the house dust mite Dermatophagoides farinae has been isolated and sequenced. It codes for a putative 18-residue signal peptide, an 80-residue proenzyme region, and a 223-residue mature protein with a derived molecular weight of 25,191. The deduced amino-acid sequence shows significant homology to other cysteine proteases in the proregion as well as in the mature protein. Sequence alignment of the mature Der f I protein with the homologous allergen Der p I from the related mite D. pteronyssinus revealed a high degree of homology (81%) between the two proteins, as predicted by previous sequencing at the protein level. In particular, the residues comprising the active site of these enzymes and the cysteine residues were conserved. A potential N-glycosylation site was present at an equivalent position in both mite allergens. It is anticipated that the availability of recombinant Der f I will facilitate epitope mapping studies and studies of T-cell function in mite allergy by providing high levels of pure allergen.     

IgE binding studies with large peptides expressed from Der p II cDNA constructs

The major mite allergen Der p II shows marked resistance to denaturation and is expressed from cDNA in bacteria with almost all of its IgE binding activity. Despite these properties, the IgE binding activity appears to be dependent on maintaining the complete primary structure. Random fragment libraries of cDNA, able to code for up to 93 of the 129 amino acid residue protein, did not express IgE binding peptides. Large overlapping peptides 1-69, 69-129 and 42-117 expressed as the fusions from the glutathione transferase of pGEX vectors only had binding activity with IgE in 15 out of 57 sera, and this was typically weak. Sera from children with atopic dermatitis bound IgE in seven out of eight cases but this was also weak compared with their strong reactivity to intact recombinant Der p II. The inability of such large peptides to form IgE binding structures suggests that the antigenic determinants of Der p II are highly conformational and restricted.     

Retrospective review of mitomycin C use as third‐line chemotherapy in metastatic colorectal cancer

The aim of this review was to determine the therapeutic value of the combination of mitomycin C with either infusional 5‐fluorouracil or oral capecitabine in metastatic colorectal cancer when used as third‐line treatment or beyond in the setting of routine clinical practice. We retrospectively reviewed 18 patients with advanced colorectal cancer who received this combination at our institution after the failure of two lines of prior treatment. All the patients were assessable for toxicity and survival and 14 for tumor response. The median age of the patients was 61 (range 39–78). Of these, 72% were male and 78% had Eastern Cooperative Oncology Group performance status 0 or 1. Eighty nine percent of the patients had metastatic involvement of the liver and five patients had at least three sites of metastatic involvement. All patients had received at least two lines of chemotherapy and had progressed on an oxaliplatin‐containing regimen. Most of the patients had previously received an irinotecan‐containing regimen, and a third had received prior biological agents. Overall, none of the patients achieved either complete or partial responses. Two patients (11%) achieved stable disease and 12 patients (67%) had progressive disease. The median progression‐free survival was 2.7 months (range 0.5–8.8) and the median overall survival was 5.4 months (range 1.3–31.2). This chemotherapy regimen was well tolerated with an acceptable toxicity profile. The results of our review confirm the low efficacy of combination mitomycin C in heavily pretreated Australian patients with advanced colorectal cancer. This review confirms that it has no role after two lines of modern combination chemotherapy regimens and recommends that focus should be placed on investigating newer agents for good performance status patients progressing after these treatments.     

Sequence polymorphism of the group 1 allergen of Bermuda grass pollen

BACKGROUND: Cyn d 1, the major allergen of Bermuda grass pollen, consists of a number of isoforms. OBJECTIVE: To examine the extent of sequence variation of Cyn d 1 isoforms at the molecular level. METHODS: A Bermuda grass pollen lambdaZAP II cDNA expression library was immunoscreened with anti-Cyn d 1 monoclonal antibodies. The reactive clones were isolated, subcloned into Escherichia coli, and sequenced. Some of them were expressed in the yeast Pichia pastoris to obtain recombinant Cyn d 1 proteins. RESULTS: Ten cDNA clones were obtained, all these clones encode the full length of Cyn d 1 protein. Their deduced mature proteins can be grouped into: the long ones with 246 amino acids, and the short ones with 244 amino acids. The last two amino acids (AG) of the long Cyn d 1 are deleted in the short Cyn d 1. The remaining amino acid sequences share more than 98% identity; a total of nine amino acid variations were observed. Two recombinant Cyn d 1 proteins (rCyn d 3-2 and rCyn d 5-4) with three amino acid substitutions showed differential IgE-binding profiles. CONCLUSION: The present study extended our understanding of the primary structure of isoforms of Cyn d 1.     

The reproducibility and comparability of tests of the peripheral chemoreflex: comparing the transient hypoxic ventilatory drive test and the single-breath carbon dioxide response test in healthy subjects

Abstract. Both the transient hypoxic ventilatory drive test and the single-breath carbon dioxide (CO₂) response test have been used to assess peripheral chemoreflex sensitivity. We tested their comparability in 14 healthy adults (10 men, aged 31–73 years, mean 55.4 years). The within-subject reproducibility of both tests was also assessed ( n = 7 for each). The mean transient hyoxic ventilatory response was 0.287 ± 0.0591min^-1 (%Sao₂)^-1 (mean ± SEM, range 0.018–0.718) and single-breath CO₂ response was 0.276 ± 0.0411 min^-1T^-1 (range 0.081–0.501). Both tests were reproducible with a mean coefficient of variation of 20.1% and 17.7%, respectively. There was, however, no significant correlation between the results of the transient hypoxic and single-breath CO₂ tests when data were compared by linear regression analysis ( r = 0.23, P = 0.43), suggesting that separate pathways of the peripheral chemoreflex existed for hypoxia and hypercapnia, respectively, and that these tests were specific for each. The authors conclude that these tests are reproducible but need to be used in combination for an adequate assessment of the peripheral chemoreflex.     

BRAIN ABSCESS DUE TO PSEUDOMONAS PSEUDOMALLEI

Abstract A brain abscess due to Pseudomonas pseudomallei is presented. Central nervous system involvement in melioidosis is rare and generally occurs in association with disseminated infection. The importance of early diagnosis and prompt treatment with prolonged antibiotic therapy is emphasised.