Characterization of alpha 2-macroglobulin from plasma of cystic fibrosis patients and controls

The physical, kinetic, and isoelectric focusing properties of native alpha 2-macroglobulin from cystic fibrosis and control plasmas were studied. No differences were found in the esterolytic activity levels of control, obligate heterozygote, and cystic fibrosis plasmas. Stability studies indicated that both control and cystic fibrosis alpha 2-macroglobulin retained full activity for at least 8 months at -20 degrees C, a week at 0-4 degrees C, 11 hr at 50 degrees C, and showed no differences in thermostability at several preincubation temperatures. The microheterogeneity of native alpha 2-macroglobulin was studied by column isoelectric focusing of five control and five cystic fibrosis plasmas. The number and pI values of the isoelectric forms between pH 4.5-8.0 were quite similar for both groups even though consistently less cystic fibrosis alpha 2-macroglobulin activity was recovered after isoelectric focusing.     

A model of the population genetics of cystic fibrosis in the United States

A model of the population genetics of cystic fibrosis is developed. It is shown that in the absence of a selective advantage the cystic fibrosis gene dies out, while in the presence of a reproductive advantage for the heterozygote the gene persists in the population.     

Quantitative variation in cystic fibrosis-associated proteins in cystic fibrosis patients,carriers, and controls

Summary Serum samples from patients with cystic fibrosis (CF), obligate heterozygotes, and normal controls have been examined by isoelectric focusing (IEF). Our results suggest that cystic fibrosis protein (CFP) is a normal serum protein exhibiting quantitative variation primarily dependent on possession of the CF allele. It is concluded that detection of CFP by IEF is an inappropriate screening test for the CF gene due to lack of specificity.     

alpha 2-Macroglobulin-proteinase complexes in cystic fibrosis serum. Analysis by monoclonal antibodies and receptor-mediated endocytosis by normal human fibroblasts

alpha 2-Macroglobulin complexed to proteinases activated during clotting of cystic fibrosis and control sera was quantitated with the complex-specific monoclonal antibody F2B2 . Similar amounts of alpha 2-macroglobulin complexes (between 40 and 90 micrograms/ml) were generated in cystic fibrosis and control sera. Endocytosis of the complexes by normal human fibroblasts was compared to the amount of complexes detected by the F2B2 -radioimmunoassay. Normal uptake was observed with 13 out of 14 cystic fibrosis sera. One cystic fibrosis serum showed strongly reduced endocytosis of the complexes. Complexes isolated from this serum on immobilized F2B2 failed to inhibit binding of purified alpha 2-macroglobulin-trypsin to its receptor, demonstrating deficient receptor-binding of these complexes. The low uptake complexes could not be distinguished from complexes isolated from control or other cystic fibrosis sera by isoelectric focusing, rate electrophoresis or SDS-polyacrylamide gel electrophoresis.     

Demonstration of a factor in the serum of homozygotes and heterozygotes for cystic fibrosis by a non-biological technique.

A factor has been isolated from serum of homozygotes and obligate heterozgotes for cystic fibrosis using isoelectric focusing and disc electrophoresis as analytical methods. The factor is focused within an IgG-fraction with an isoelectric point of pH 8 to 9 but differs from IgG in its lower molecular weight. It is thus similar to, if not identical with, the ciliary dyskinesia factor.     

Decreased rate of cytolysis of Colpidium striatum by cystic fibrosis serum. I. Bioassay and evidence for the possible involvement of a C/F factor--IgG complex

Treatment of the protozoan ciliate $\text{Colpidium}$$\text{striatum}$ with whole serum from cystic fibrosis (C/F) patients, their parents (obligate heterozygote carriers), and normal controls uniformly caused complete cytolysis of the protozoa. At a 1:10 dilution of serum, a distinct decrease in the rate of cytolysis was found for 16 out of 19 cystic fibrosis patients, and 12 out of 16 heterozygote samples. An investigation into the cause of the decreased cytolytic rate indicated that a serum component associated with the IgG fraction from homozygote and heterozygote serum was responsible for the decreased rate.     

The selective advantage of cystic fibrosis heterozygotes tested by aDNA analysis: A preliminary investigation

Recently a heterozygote advantage was suggested to explain the high incidence (1:25 carrier individuals in Europeans) of the cystic fibrosis gene. This selective advantage was speculated to be due to a high resistance to chloride-secreting diarrhea, including cholera. Up to now the major efforts to test directly this hypothesis have been limited to animal models. We propose to verify the hypothesis directly on a sample of human individuals who died from cholera during the epidemic in the Mediterranean basin at the beginning of the nineteenth century. In this preliminary investigation we have attempted to check for the presence of amplifiable DNA in the human remains simultaneously in terms of genetic fingerprints and for cystic fibrosis mutations.     

Decreased inhibition of platelet aggregation by PGE1 in children with cystic fibrosis and their parents

PGE₁ inhibited ADP-induced platelet aggregation in children with cystic fibrosis and their parents to a much lesser extent than in normal controls. We suggest that this may be a reliable test for heterozygote carriers of cystic fibrosis.     

Study of pyoverdine type and production by Pseudomonas aeruginosa isolated from cystic fibrosis patients: prevalence of type II pyoverdine isolates and accumulation of pyoverdine-negative mutations

The lungs of cystic fibrosis patients are frequently colonized by Pseudomonas aeruginosa, which produces high-affinity fluorescent peptidic siderophores, pyoverdines. Three pyoverdines which differ in their peptide chain and are easily differentiated by isoelectric focusing exist, only one being produced by a given strain. P. aeruginosa isolates from cystic fibrosis patients of a German hospital were analyzed by sequential, pulse-field gel electrophoresis (PFGE) and for pyoverdine production and type. Only producers of type I and type II pyoverdine were found. There was a perfect correlation between the type of pyoverdine produced and the clonality determined by PFGE. PFGE clone C, the most prevalent among cystic fibrosis patients, and found in an aquatic environment, produced type II pyoverdine. Pyoverdine-negative mutants seemed to increase as a function of the lung colonization time, but retained the capacity to take up pyoverdines. Most isolates that took up type II pyoverdine were also able to utilize type I pyoverdine as judged by growth stimulation experiments. No correlation was observed between the loss of pyoverdine production and mucoidy.     

α2-Macroglobulin-proteinase complexes in cystic fibrosis serum Analysis by monoclonal antibodies and receptor-mediated endocytosis by normal human fibroblasts

α₂-Macroglobulin complexed to proteinases activated during clotting of cystic fibrosis and control sera was quantitated with the complex-specific monoclonal antibody F₂B₂. Similar amounts of α₂-macroglobulin complexes (between 40 and 90 μg/ml) were generated in cystic fibrosis and control sera. Endocystosis of the complexes by normal fibroblasts was compared to the amount of complexes detected by the F₂B₂-radioimmunoassay. Normal uptake was observed with 13 out of 14 cystic fibrosis sera. One cystic fibrosis serum showed strongly reduced endocytosis of the complexes. Complexes isolated from this serum on immobilized F₂B₂ failed to inhibit binding of purified α₂-macroglobulin-trypsin to its receptor, demonstrating deficient receptor-binding of these complexes. The low complexes could not be distinguised from complexes isolated from control or other cystic fibrosis sera by isoelectric focusing, rate electrophoresis or SDS-polyacrylamide gel electrophoresis.     

Cystic fibrosis: present status and future prospects in detection of patients and carriers.

Development of a sensitive, easily performed, reliable test would be an important advance in detecting cystic fibrosis, improving genetic counselling and providing early effective treatment. The sweat chloride test, which is reliable in diagnosis, is technically too difficult for a screening program, and only reliably detects homozygotes. In contrast, the meconium test for detecting homozygote newborns is simple, inexpensive, reasonably specific but its general application has yet to be evaluated. Detection of serum components is the basis of two new tests to distinguish patients with cystic fibrosis and carriers. The effect of these serum components on ciliary activity is the principle of one test, an extremely difficult procedure that is subjective and lacks sufficient specificity for routine use. The second test, in which serum components are separated by isoelectric focusing, may provide an objective biochemical means of detecting both homozygotes and heterozygotes.     

Frequency of the F508 deletion in the CFTR gene in Turkish cystic fibrosis patients

Summary The F508 deletion in the cystic fibrosis transmembrane conductance regulator (CFTR) gene was found in 8 out of 30 Turkish cystic fibrosis (CF) chromosomes (27%). Five Turkish ΔF508 CF chromosomes were associated with the risk haplotype B in KM19 (2 allele)/XV2c (1 allele). In the Turkish population, cystic fibrosis is predominantly caused by mutations other than the F508 deletion.     

The deletion F508 is the major gene mutation in a representative Belgian cystic fibrosis population

Summary The cystic fibrosis (CF) gene deletion F508 was studied in a Belgian population of 74 families and their 83 CF children. The haplotypes for CF and normal chromosomes had previously been determined with several linked DNA probes. In our CF population, the gene deletion F508 was found in 76% of the mutant alleles. Of the deletion F508, 97% segregated with the highest risk haplotype for the CF carrier status. Some 61% of our families were found to be homozygous for this major CF mutation. Each of our three pancreatic sufficiency patients (two of whom were siblings) was heterozygote for the F508 deletion.     

Heterogeneity in the severity of cystic fibrosis and the role of CFTR gene mutations

Cystic fibrosis is a common, fatal disorder caused by abnormalities in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CFTR encodes a chloride channel that regulates secretion in many exocrine tissues. The presentation of cystic fibrosis is highly variable as measured by the age of onset of disease, the presence of pancreatic insufficiency, or the progression of lung disease. Over 400 mutations in the CFTR gene have been described in cystic fibrosis patients and considerable effort has focused on the correlation between specific mutations and genotypes and clinical characteristics. Individual tissues display variation in their sensitivity to CFTR mutations. The vas deferens is functionally disrupted in nearly all males, whereas mild and severe pancreatic involvement is determined by the patient's genotype. The severity of pulmonary disease is poorly correlated with genotype, suggesting that there are other important genetic and/or environmental factors that contribute to lung infections and the subsequent disruption of lung function.     

Absence congenitale des canaux deferents: Phenotype genital de la mucoviscidose?

Because spermatogenesis is typically normal in men with bilateral agenesis of the vas deferens, epididymal sperm recovery for subsequent use in in-vitro fertilization (IVF) has recently been proposed for such patients. The discovery of the presence of mutations in the cystic fibrosis gene in such patients has indicated that this disease might constitute a genital phenotypie concomitant of cystic fibrosis, and has profound genetic implications if the spouse is heterozygous. Testing for mutations of the cystic fibrosis gene, and the provision of genetic counselling as appropriate, should be performed in patients, and their partners, when IVF is being considered for such couples presenting with infertility. The main characteristics of the cystic fibrosis gene and its mutations are discussed, with particular reference to problems in identifying mutations among the 27 exons encoding the gene’s product     

Four Novel Cystic Fibrosis Mutations in Splice Junction Sequences Affecting the CFTR Nucleotide Binding Folds

Single cases of the four novel splice site mutations 1525-1G & rarr; A (intron 9), 3601 2A → G (intron 18), 3850 3T → G (intron 19), and 4374 → 1G → T (intron 23) were detected in the CFTR gene of cystic fibrosis patients of Indo-Iranian, Turkish, Polish, and German descent. The nucleotide substitutions at the +1, -1, and -2 positions all destroy splice sites and lead to severe disease alleles associated with features typical of gastrointestinal and pulmonary cystic fibrosis disease. The 3850 -- 3 T-to-G change was discovered in a very mildly affected 33-year-old ΔF508 compound heterozygote, suggesting that the T-to-G transversion at the less conserved -3 position of the acceptor splice site may retain some wildtype function.     

Cloning the mouse homolog of the human cystic fibrosis transmembrane conductance regulator gene.

The cystic fibrosis transmembrane conductance regulator is encoded by the gene known to be mutated in patients with cystic fibrosis. This paper reports the cloning and sequencing of cDNAs for the murine homolog of the human cystic fibrosis transmembrane conductance regulator gene. A clone that, by analogy to the human sequence, extends 3' from exon 9 to the poly(A) tail was isolated from a mouse lung cDNA library. cDNA clones containing exons 4 and 6b were also isolated and sequenced, but the remainder of the mRNA proved difficult to obtain by conventional cDNA library screening. Sequences spanning exons 1-9 were cloned by PCR from mouse RNA. The deduced mouse protein sequence is 78% identical to the human cystic fibrosis transmembrane regulator, with higher conservation in the transmembrane and nucleotide-binding domains. Amino acid sequences in which known cystic fibrosis missense mutations occur are conserved between man and mouse; in particular, the predicted mouse protein has a phenylalanine residue corresponding to that deleted in the most common human cystic fibrosis mutation (delta F508), which should allow the use of transgenic strategies to introduce this mutation in attempts to create a "cystic fibrosis mouse".     

Assessment of the tracheal ring bioassay for detection of the cystic fibrosis serum factor

We have examined the effects of serum from cystic fibrosis patients, healthy human volunteers and from guinea pigs on ciliary activity of guinea pig tracheal ring explants after 48 hours in culture. Sera from 9 out of 10 cystic fibrosis patients produced ciliostasis. This is a significantly greater percentage than the 7 out of 21 serum samples from healthy volunteers that produced ciliostasis. Ninety-two percent of the explants in guinea pig serum had unaltered ciliary activity, illustrating the importance of intrinsic control in the bioassay design. These result suggest that the guinea pig tracheal ring bioassay may be of value as a means of identifying the presence of the ciliotoxic factor in cystic fibrosis serum for research use but is a poor discriminator for diagnostic purposes. Modification such as rinsing the tracheal mucosa with sterile medium and a new chamber for the microscopic observation of the tissue have simplified the assay.     

Surface enzymes in cultured fibroblasts from cystic fibrosis patients.

Membrane function was examined in cultured cells from cystic fibrosis patients by assaying several enzymes on intact skin fibroblasts attached to culture dishes. This technique required few cells and minimized disruption of cellular organization. Comparison of enzyme activities of intact and broken cells showed that 12% of total glucose-6-phosphate dehydrogenase, a cytoplasmic enzyme, was measurable using intact cells, while all adenosine monophosphatase was measurable using intact cells. Alkaline paranitrophenylphosphatase activity was divided between the cell surface and interior. Substrate competition experiments indicated that substrate specificities for adenosine monophosphatase and paranitrophenylphosphatase activities were different. Adenosine monophosphatase activities of 2 control and 2 cystic fibrosis strains fluctuated similarly during the cell culture cycle. The apparent Km values relative to adenosine monophosphate were similar in all strains. A chromatographic fraction of serum from a cystic fibrosis patient that was inhibitory to oyster ciliary activity had no effect on adenosine monophosphatase activity of normal fibroblasts. Furthermore, fractions of media from cystic fibrosis homozygote and heterozygote fibroblast cultures were not inhibitory to adenosine monophosphatase activities of intact normal fibroblasts or of part iculate fractions prepared from them. In light of previous studies that showed that factors from cystic fibrosis serum of culture medium disrupted specific membrane activities, it is proposed that the cystic fibrosis factor interacts with the plasma membrane, interfering most conspicuously with the protein functions that are sensitive to changes in their membrane environment.