Structure and chromosomal localization of chicken CD5.

CD5 is a transmembrane glycoprotein on all T cells and on a subpopulation of B cells. Based on the analysis of chicken CD5-cDNA we have previously shown that the structure of the CD5 protein is conserved between species. Here we report the isolation and chromosomal mapping of the chicken CD5 gene. The gene spans 3.4 kb and is extremely compact with a high GC-nucleotide content. There are 10 exons and the introns are spliced out similarly to those in the human CD5 gene. Each of the three extracellular scavenger receptor cysteine-rich (SRCR) domains is encoded as an exon of its own, as is the proline-rich hinge region that separates the first two membrane-distal SRCR domains. The fluorescence in situ hybridization (FISH) technique was used to map the gene to chromosome five. This is the first report describing the organization of the CD5 gene from a nonmammalian species.

Characterization of Sphingomonas isolates from Finnish and Swedish drinking water distribution systems.

Sphingomonas species were commonly isolated from biofilms in drinking water distribution systems in Finland (three water meters) and Sweden (five water taps in different buildings). The Sphingomonas isolates (n = 38) were characterized by chemotaxonomic, physiological and phylogenetic methods. Fifteen isolates were designated to species Sphingomonas aromaticivorans, seven isolates to S. subterranea, two isolates to S. xenophaga and one isolate to S. stygia. Thirteen isolates represented one or more new species of Sphingomonas. Thirty-three isolates out of 38 grew at 5 degrees C on trypticase soy broth agar (TSBA) and may therefore proliferate in the Nordic drinking water pipeline where the temperature typically ranges from 2 to 12 degrees C. Thirty-three isolates out of 38 grew at 37 degrees C on TSBA and 15 isolates also grew on blood agar at 37 degrees C. Considering the potentially pathogenic features of sphingomonas, their presence in drinking water distribution systems may not be desirable.

Cloning and modeling of the first nonmammalian CD4.

We have cloned and sequenced the first nonmammalian CD4 cDNA from the chicken using the COS cell expression method. Chicken CD4 contains four extracellular Ig domains that, in analogy to mammalian CD4, are in the order V, C2, V, and C2. The molecule is 24% identical with both human and mouse sequences. The extracellular domains were modeled using human and rat CD4 crystal structures as templates. In the first domain there are two extra Cys residues that are at suitable distance to form an intra-beta-sheet disulfide bridge in addition to the canonical one in the V domain. The region responsible for the interaction with MHC class II is relatively nonconserved in chicken. However, there are positively charged amino acids in the C" region of the N-terminal domain that may mediate the association to the negatively charged residues of the MHC class II beta-chain. Molecular modeling also implies that the membrane-proximal domain mediates dimerization of chicken CD4 in a similar way as it does for human CD4. Furthermore, the cytoplasmic tail is highly conserved, containing the protein tyrosine kinase p56lck recognition site that is preceded by an adjacent di-leucine motif for the internalization of the molecule. Interestingly, there are no Ser residues in the cytoplasmic part, which may explain the slow down-regulation of chicken CD4 after phorbol ester stimulation.

The structure of avian CD5 implies a conserved function.

The chicken CD5 cDNA was isolated by COS cell expression cloning utilizing a novel mAb 2-191. The cDNA contains a 1422-nucleotide open reading frame encoding a mature protein with 32% and 30% identity to mouse and human CD5 polypeptides, respectively. The molecule consists of a 330-amino acid extracellular region with three repeats of the scavenger receptor cysteine-rich domain, a 29-amino acid hydrophobic transmembrane domain, and a 93-amino acid cytoplasmic tail. The cytoplasmic region contains motifs that are highly conserved between species, including several potential phosphorylation sites. The chicken CD5 is a 64-kDa phosphorylated glycoprotein with a protein core of 57 kDa as determined by immunoprecipitation and SDS-PAGE analysis. Alphabeta T cells express a homogeneously high level of CD5, whereas low or intermediate CD5 expression on gammadelta T cells depends on their tissue location. In contrast to human and mouse, CD5 is found at low levels on all chicken B cells. The high conservation of structural features, as well as signaling motifs, implies a conserved role for CD5 both in lymphocyte development and function.

Chlamydia pneumoniae infection in patients with chronic obstructive pulmonary disease.

The prevalence of chronic Chlamydia pneumoniae infection was assessed in 54 patients with established chronic obstructive pulmonary disease (COPD), 41 of these with severe COPD (group I), 13 with mild to moderate COPD (group II), and in 23 patients with community-acquired pneumonia (controls, group III). Specific IgG and IgA antibody levels and circulating immune complexes (ICs) were measured in paired sera, and specific secretory IgA (sIgA) levels in sputum specimens. A polymerase chain reaction (PCR) test was used for the detection of C. pneumoniae in sputum. According to our definite diagnosis criterion, 65% of the COPD patients showed evidence of suspected chronic C. pneumoniae infection and the prevalence was still higher (71%) in patients with severe disease. The occurrence of specific markers of infection was invariably highest in patients with severe COPD, next-highest in patients with mild to moderate COPD and lowest in pneumonia patients. The association between COPD and C. pneumoniae infection persisted after controlling for the potential confounding factors.

Chlamydia pneumoniae antibodies in chronic obstructive pulmonary disease.

BACKGROUND: The significance of persistent or recurrent respiratory infections in adult life for the development of chronic obstructive pulmonary disease (COPD) is still to a large extent unknown. A few clinical and experimental animal studies suggest that peripheral airways diseases may be due to the cumulative effects of recurrent respiratory infections over an extended period. METHODS: C. pneumoniae-specific IgG and IgA antibody levels were determined in two elderly groups of male patients with COPD and in control subjects without the disease. The first group (N = 36) consisted of patients who were hospitalized due to an acute exacerbation of COPD. The second group of patients (N = 54) and the controls (N = 321) were participants in a community survey on respiratory diseases in the elderly. The criteria for seropositivity were defined as an IgG titre of >=16. RESULTS: 89% of the hospitalized patients (group I) and 66% of the non-hospitalized patients (Group II) were IgA seropositive as compared to 55% of the controls. Derived from the logistic regression analysis, the odds ratio (OR) WAS 7.4 (95% CI : 2.1-25.7) between group I and the controls and 1.5 (0.7-2.9) between group II and controls. Furthermore, the difference in the age-adjusted geometric mean titres (GMT) of lgA antibodies between the group I and the controls was significant (53.0 for the patients versus 19.1 for the controls). On the contrary, no significant differences between the patients and the controls were found either in the proportion of IgG-seropositive or in the GMT of IgG antibodies. Two of the 29 patients with an exacerbation of COPD, for whom paired sera were available, showed an antibody response suggesting a current acute or reactivated chlamydial infection. CONCLUSIONS: The results showed that C. pneumoniae lgA antibodies are found more frequently and in higher concentrations in COPD patients than in disease-free controls. The finding may indicate a chronic C. pneumoniae infection in these patients. The association persisted after controlling for the potential confounding effect of smoking.

Characterization of chicken CD8-specific monoclonal antibodies recognizing novel epitopes.

CD8 is a heterodimeric cell surface glycoprotein expressed primarily on thymocytes and a subpopulation of mature T lymphocytes. It binds to the invariant part of the major histocompatibility complex class I molecule and participates in antigen recognition by the major histocompatibility complex class I restricted T cells. As in mammalian species, the majority of chicken thymocytes express both CD4 and CD8, whereas peripheral T cells are either CD4- or CD8-positive. We have created a panel of mouse monoclonal antibodies detecting different cell surface epitopes on chicken CD8. The antibodies precipitate a 32-34 kDa dimeric protein from surface labelled thymocytes under reducing conditions. The identical N-deglycosylation pattern confirms that these MoAb precipitate the same heterodimeric molecule from chicken thymocyte lysates. Binding of 11-38 and 11-39 MoAb to peripheral blood T cells is totally inhibited by 11-39 and previously characterized CT8 and EP72 MoAb, further confirming their CD8 specificity. CD8 alpha-chain specificity of MoAb 11-39, 11-38, 11-30 and 11-13 is conclusively proven by staining COS-cells transfected with a plasmid containing CD8 alpha cDNA. However, MoAb 11-13, 11-30 and 11-38 do not compete with MoAb 11-39 in binding to CD8. These results demonstrate recognition of different epitopes by these MoAb. Monoclonal antibodies detecting novel epitopes on chicken CD8 provide a valuable tool for further studies on T cell development.

Gradual and rapid weight loss: effects on nutrition and performance in male athletes.

We studied seven male wrestlers and three judo athletes (weight 55-93 kg) during two weight reductions. In the "gradual" procedure (GP), a 5.0 +/- 0.4% (mean +/- SEM) weight loss was achieved in 3 weeks by energy restriction. In the "rapid" procedure (RP), 6.0 +/- 0.6% of body weight was lost in 2.4 days by fluid and diet restriction and forced sweating, and followed by a 5-h "loading" (food and drinks ad libitum). The net weight loss after GP and loading was 2.7 +/- 0.5%. Protein intakes (4-d food records) during GP and RP were 71 +/- 16 and RP 56 +/- 17 g.d-1, respectively. Carbohydrate intakes were 239 +/- 56 (GP) and 182 +/- 55 g.d-1 (RP). During GP and RP, mean thiamin, magnesium, and zinc intakes were at or below the respective recommendation. Thiamin, riboflavin, potassium, iron, and zinc status, assessed from blood chemistry, remained stable during both procedures. Changes in vitamin B6 indicator (E-ASTAC) and S-magnesium concentration were different (P < 0.01) between the procedures, suggesting negative trends during GP. Sprint (30-m run) and anaerobic (1-min Wingate test) performance was similar throughout the study. Following GP, vertical jump height with extra load increased by 6-8% (P < 0.01). Jumping results were not affected by RP. Hence, < or = 5% loss in body weight by either method did not impair experienced athletes' performance.

Effect of aluminium hydroxide and glycopyrrhonium on the absorption of ethambutol and alcohol in man.

1 The effect of aluminium hydroxide and/or of glycopyrrhonium on the absorption of a single oral 50 mg/kg dose of ethambutol (EMB) was investigated on thirteen tuberculous in-patients and on two groups of healthy volunteers with six subjects each. The EMB concentrations in serum and 10+h urine were measured by colorimetry. 2 In order to assess gastric emptying the healthy volunteers ingested ethanol, either 0.5 g/kg in 10% solution or 0.8 g/kg in 20% solution, simultaneously with the drug, and breath alcohol levels were measured repetitively. 3 Aluminium hydroxide significantly lowered the serum EMB levels of the patients during the first 4 h after the EMB intake. No consistent effect was found in the first student experiment, whereas in the second experiment aluminium hydroxide and glycopyrrhonium, alone or in combination, clearly retarded the EMB absorption. 4 Repeated breath alcohol analysis proved unsuitable to indicate the time course of gastric emptying in these circumstances.