Brain clathrin. Viscometric and turbidimetric properties of its ultrastructural assemblies.

Clathrin was isolated in highly purified form from bovine brain preparations rich in coated vesicles and by some improvements of our previous procedures. At pH 7.5, clathrin's solution was viscous, but clear. At pH 6.5, clathrin's solution was less viscous, but turbid. By electron microscopy, clathrin's turbidity at pH 6.5 correlated with the presence of numerous basket-like lattices or cages; the higher viscosity observed at pH 7.5 correlated with a mixture of various polymeric forms of clathrin having linearly assembled filaments or filamentous bundles of cross-linked clathrin molecules. In vivo, clathrin's capacity for assembling or disassembling itself into baskets or cage-like structures is compatible with a mechanism that retrieves areas of the plasma membrane containing protein molecules, smaller stimulatory or inhibitory compounds bound on the external cell membrane surface.

Ciprofloxacin therapy in cystic fibrosis.

There is great need for an oral agent that could be used to treat pulmonary exacerbations in patients with cystic fibrosis. In this study, the use of oral ciprofloxacin as sole therapy was evaluated in 18 patients with 39 infectious episodes; 13 episodes were classified as severe, 19 were classified as moderate, and seven were classified as mild. Patients ranged in age from eight to 36 years (mean, 23 years). Dosage varied according to severity of disease, body size, and the susceptibility of the Pseudomonas isolate to ciprofloxacin; the dose ranged from 750 to 2,250 mg daily (mean, 1,800 mg). Ten patients received one course of ciprofloxacin, and eight received repeated courses. The overall clinical response rate was 82 percent. There was a response to the initial treatment course in 96 percent of the patients. Those in whom therapy failed had been re-treated with ciprofloxacin and were severely ill. Failure to respond correlated poorly with pretreatment minimal inhibitory concentration (MIC) values (0.6 microgram/ml for failures versus 0.4 microgram/ml for responses). Pseudomonas could not be eradicated from the sputum of any of the patients, although there was a marked reduction in purulence and bacterial counts. In general, patients who did not require re-treatment for three months would again have susceptible organisms. When organisms became resistant to ciprofloxacin (MIC greater than 2 micrograms/ml), they showed no concomitant new aminoglycoside or beta-lactam resistance. No serious toxicity occurred in any of the 39 episodes of treatment. In seven patients treated with combination therapy (tobramycin or azlocillin), the infecting organisms were reduced in number, but eradication of Pseudomonas generally could not be achieved. Increases in MIC occurred during combination therapy. Ciprofloxacin is a major advance in the treatment of bronchopulmonary infection in patients with cystic fibrosis.

Clinical spectrum in homozygotes and compound heterozygotes inheriting cystic fibrosis mutation 3849 + 10kbC > T: significance for geneticists.

We describe patients inheriting cystic fibrosis (CF) mutation 3849 + 10kb > T as homozygotes or compound heterozygotes. Three unrelated homozygotes for this mutation were all pancreatic-sufficient and sweat test-negative or inconclusive. Among the compound heterozygotes, both pancreatic sufficiency and insufficiency, as well as positive and negative/inconclusive sweat test results are reported, expanding the range of clinical expression associated with inheritance of this mutation. 3849 + 10kbC > T is one of several CF mutations that can result in atypical or variant forms of CF. For geneticists, the diagnosis of variant CF has implications for recurrence risk and prognosis counseling of the families of affected individuals, and possibly for CF carrier screening in the general population.

Cerebral dysfunction following infantile dietary chloride deficiency.

Twenty-two children who were chloride-depleted in infancy due to a chloride-deficient diet and who had resultant hypochloremic alkalosis were analyzed in regard to their signs and symptoms, metabolic studies, and growth parameters. Deceleration of weight, linear growth, and head growth occurred in most, and persistent growth failure occurred in some. The majority had cognitive deficits at follow-up. Comparison with growth parameters in a chronically malnourished group of children who had a variety of disorders revealed a similar degree of deceleration of weight (p = 0.50) and height (p = 0.70), but more severe deceleration of head growth (p = 0.01). Comparison with follow-up cognitive deficits reported in the United States medical literature in children with similar severity of nutritional deprivation indicates that the chloride-depleted infants had more frequent and more severe cognitive deficits (p = 0.09). Cognitive deficits have been documented in U. S. children who are nutritionally deprived only when disorders causing concomitant chloride depletion are responsible for the malnutrition.

Fatal desquamative interstitial pneumonia in an infant: case report with transmission and scanning electron microscopical studies.

Desquamative interstitial pneumonia in a young infant followed a rapidly fatal course and developed morphologic features of honey-combing, giant cell pneumonia, and pulmonary alveolar proteinosis. The rapid and fatal progression of the disease in spite of steroid therapy and the polymorphous histologic appearance of the lungs at autopsy raise doubt that the disease is a relatively benign and uniform entity and invalidate the classical initial histologic features as prognostic indicators.

Isolation and properties of brain alpha-actinin.

alpha-Actinin isolated from bovine brain migrated on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis like muscle alpha-actinin with an apparent mol.wt. of 100000 and cross-reacted with antibodies to muscle alpha-actinin. Brain alpha-actinin modulated actin-myosin Mg2+-activated adenosine triphosphatase activity and, when bound by polystyrene particles, was found to bind muscle actin and tropomyosin from solution. Brain alpha-actinin, in conjunction with the other components of the contractile and relaxing complex, may play a role in the release of neurotransmitters from synaptic vesicles.

Treatment of lower respiratory tract infections due to Pseudomonas aeruginosa in patients with cystic fibrosis.

Twelve patients who underwent 26 episodes of lower respiratory tract infection due to Pseudomonas aeruginosa were treated with aztreonam. Infectious episodes were severe in 11 patients, moderate in 10 patients, and mild in five patients. In 85% of the episodes, significant clinical improvement occurred, but in four severe episodes, the clinical response was unsatisfactory. The mean interval between initiation of treatment and improvement was seven days. Aztreonam was as clinically effective in the treatment of infections due to organisms susceptible to penicillins active against Pseudomonas as it was in the treatment of infections due to organisms resistant to these agents. P. aeruginosa was not permanently eradicated from the sputum of any of the patients treated with aztreonam. It did not cause any major adverse effects, and the only laboratory abnormality found was an increase in alkaline phosphatase, which occurred during 12 (46%) courses of therapy. Levels of alkaline phosphatase returned to normal after conclusion of treatment. Aztreonam was shown to be clinically effective in the treatment of lower respiratory infections due to P. aeruginosa in patients with cystic fibrosis.

Mechanochemical properties of brain clathrin: interactions with actin and alpha-actinin and polymerization into basketlike structures or filaments.

Two molar urea (pH 7.5) and column chromatography on Sepharose 4B were used to separate clathrin (coat protein) from the membrane of coated vesicles from bovine brain. Lytron (polystyrene) particles were used for study of the interaction of clathrin with contractile proteins. Muscle G-actin, F-actin, and alpha-actinin were bound by clathrin-coated Lytron particles, while no interaction was found when muscle tropomyosin and serum albumin were tested. Clathrin molecules dispersed in a solution of 20 mM Tris-HCl (pH 7.5) were found to be elongated. When the pH was adjusted from 7.5 to 6.5, clathrin molecules associated into basketlike or cage structures similar in size and shape to those observed in enriched preparations of coated vesicles. Below pH 6.0, cages or baskets became amorphous aggregates. Raising the pH from 6.5 to 8.0, addition of 5-10 mM ATP or EDTA, or addition of 200 mM KCl resulted in the dissassembly of baskets and the formation of filamentous arrays of various widths. Because of clathrin's biochemical and biophysical properties, its interaction with contractile proteins, and its presence in the membrane of vesicles of various cell types, we classified clathrin in the group of mechanochemical proteins.

Brain clathrin and clathrin-associated proteins.

The assembly of clathrin into baskets or cages in vitro may depend on formation of complex between clathrin and a polypeptide doublet migrating in the 30000-mol.wt. region. Clathrin with several associated proteins was isolated from coated-vesicle fractions of bovine cerebral cortex. Most associated proteins were separated by Sepharose 4B column chromatograhy. The eluted clathrin retained only the 30000-mol.wt. doublet and assembled into baskets at pH 6.5. Limited proteolysis of coated vesicles or clathrin assembled as baskets removed these clathrin-associated proteins (CAPs) without detectably altering clathrin. Enzyme-treated clathrin assembled into open-lattice structures but no longer formed baskets in vitro. Latex particles with bound enzyme cleaved the CAPs from coated vesicles and clathrin baskets, suggesting that the CAPs protrude from the exterior of the clathrin lattice.

Phosphorylation of brain synaptic and coated vesicle proteins by endogenous Ca2+/calmodulin- and cAMP-dependent protein kinases.

Phosphorylation of brain synaptic and coated vesicle proteins was stimulated by Ca2+ and calmodulin. As determined by 5-15% sodium dodecylsulfate (SDS) polyacrylamide gel electrophoresis (PAGE), molecular weights (Mr) of the major phosphorylated proteins were 55,000 and 53,000 in synaptic vesicles and 175,000 and 55,000 in coated vesicles. In synaptic vesicles, phosphorylation was inhibited by affinity-purified antibodies raised against a 30,000 Mr protein doublet endogenous to synaptic and coated vesicles. When this doublet, along with clathrin, was extracted from coated vesicles, phosphorylation did not take place, implying that the protein doublet may be closely associated with Ca2+/calmodulin-dependent protein kinase. Affinity-purified antibodies, raised against clathrin used as a control antibody, failed to inhibit Ca2+/calmodulin-dependent phosphorylation in either synaptic or coated vesicles. Immunoelectron cytochemistry revealed that this protein doublet was present in axon terminal synaptic and coated vesicles. Synaptic vesicles also displayed cAMP-dependent kinase activity; coated vesicles did not. The molecular weights of phosphorylated synaptic vesicle proteins in the presence of Mg2+ and cAMP were: 175,000, 100,000, 80,000, 57,000, 55,000, 53,000, 40,000, and 30,000. Based on the different phosphorylation patterns observed in synaptic and coated vesicles, we propose that brain vesicle protein kinase activities may be involved in the regulation of exocytosis and in retrieval of synaptic membrane in presynaptic axon terminals.

Immunocytochemical characterization of clathrin-associated proteins (CAPs). I. Neuronal distribution of CAPs, a component of clathrin-coated vesicles.

Clathrin-associated proteins (CAPs) elicited antibodies in rabbits that were affinity-purified using CAPs-conjugated CNBr-Sepharose 4B. Anti-CAPs IgG formed immunoprecipitates with CAPs and with the clathrin-CAPs complex. Indirect immunoperoxidase-labeling in sections of rat brain cortex using anti-CAPs and anti-clathrin IgG yielded similar staining patterns. Coated perinuclear cisternae and coated vesicles became stained and easily distinguished. Intense staining also was found in synaptic boutons with label between most synaptic vesicles and as a thick crust surrounding coated vesicles. The data demonstrate that clathrin and CAPs polypeptides are in identical subcellular locations.

Treatment of pulmonary infections in patients with cystic fibrosis: a comparative study of ticarcillin and gentamicin.

The effectiveness of ticarcillin against Pseudomonas aeruginosa in acute exacerbations of pulmonary infection in patients with cystic fibrosis was evaluated. Seventy-one percent of patients treated with ticarcillin alone responded favorably. The response rate was similar in patients treated with a combination of ticarcillin plus gentamicin or with gentamicin alone. Severity of the underlying disease was the most important determinant of response to treatment. Ticarcillin-resistant organisms were recovered during treatment in 50% of patients who received this drug; recovery of them was not prevented by the inclusion of gentamicin in the therapeutic regimen nor did they interfere with clinical improvement. The ticarcillin-resistant strains persisted at follow-up, two to six months after completion of therapy, in only one of ten patients. No serious toxicity to ticarcillin was noted during the study period.

alpha-Actinin and tropomyosin interactions with a hybrid complex of erythrocyte-actin and muscle-myosin.

alpha-Actinin isolated from dog muscle was used to incite antibodies in rabbits, Antibodies, purified by affinity chromatography on CNBr-Sepharose coupled with alpha-actinin and then ferritin-labeled were found to localize on the Z disc of muscle sarcomeres. Molecules of alpha-actinin as an adsorbed monolayer on the surface of polystyrene Lytron particles could bind muscle-actin and tropomyosin from solution. Both the ATPase activity and superprecipitation of an erythrocyte-actin and muscle-myosin hybrid actomyosin complex were altered by alpha-actinin, while tropomyosin diminished these alpha-actinin effects. The binding properties of alpha-actinin are consistent with those of an anchoring protein for microfilaments in nonmuscle cells.

Brain clathrin: studies of its ultrastructural assemblies.

Clathrin purified to a high degree of homogeneity showed the presence of accompanying polypeptides of lower molecular weights and assembled into baskets or cages when the pH of its solution was adjusted from pH 7.5 to 6.5. Brief chymotrypsin treatment of this clathrin preparation at pH 6.5 cleaved clathrin-associated proteins rendering clathrin unable to reform baskets. Hydrolysis of clathrin-associated proteins did not affect clathrin's capacity to polymerize into open lattices or to bind actin and alpha-actinin from solution. When open lattices formed, the turbidity of the solution rose to levels that were higher than those produced when cages or baskets were formed by native clathrin. In both native or enzyme-treated clathrin, turbidity increase was inhibited by salts. The addition of certain cytoskeletal-disrupting agents, such as chlorpromazine and imipramine, increased clathrin's turbidity but did not result in formation of the baskets. Colchicine and cytochalasin B did not affect turbidity or the assembly of cages. The addition of increasing amounts of vinblastine resulted in the precipitation of larger amounts of clathrin which, after solubilization, retained its ability to polymerize into baskets. It seems that clathrin exists as a complex with other protein molecules, clathrin-associated proteins, that modulate the extent of polymerization and assembly the clathrin into characteristic structures.

Immunocytochemical characterization of clathrin-associated proteins (CAPs). II. Immunolocalization of CAPs using selectively-absorbed IgG solutions.

Utilizing antibodies elicited by clathrin-associated proteins (CAPs) absorbed with three different antigenic states of CAPs, i.e., bound to clathrin (clathrin-CAPs complex), free in solution (CAPs) or partially cleaved by chymotrypsin (CAPs-subfragments), indicated that when CAPs are bound to clathrin an antigenic site (or sites) remain(s) unexposed and CAPs-subfragments lose antigenic sites as a result of limited proteolysis. IgG remaining in solution after absorption with CAPs-subfragments were directed against the chymotrypsin-sensitive, or accessible portions of CAPs, whereas IgG remaining after absorption with clathrin-CAPs complex were directed against the unexposed antigenic site(s) characteristic of the clathrin-CAPs complex. Immunocytochemical characterization of these selectively-absorbed IgG solutions suggests that CAPs detected during immunolocalization exist as a complex with clathrin.

Short-term pulmonary effects of total parenteral nutrition in children with cystic fibrosis.

Indices of respiratory muscle strength, pulmonary function, and pulmonary diffusing capacity were measured in 11 malnourished children (age 10 to 17 years) with cystic fibrosis, before and after improvement of nutritional status with supplemental parenteral nutrients for 1 month. During this time, the children received 120% of estimated energy requirements (either 3.75% or 22.5% as lipid) and amino acids 2.5 gm/120 kcal by central venous catheter, plus as much of their usual diet as desired. With nutritional supplementation, body weight, triceps skinfold thickness, and mid-arm muscle circumference increased (mean 15%, 62%, and 95%, respectively). Maximum inspiratory airway pressure also increased (mean 29%; P less than 0.01), suggesting improvement in respiratory muscle strength. However, none of the indices of pulmonary function improved. Pulmonary diffusing capacity did not change during parenteral nutrition regardless of the amount of parenteral energy intake supplied by lipid, but arterial oxygen saturation decreased (mean of 93.5% to 91.5%; P less than 0.005). During the month following parenteral nutrition, weight, skinfold thickness, and mid-arm muscle circumference, but not MIP, decreased and arterial oxygen saturation returned to the initial value (P less than 0.01).