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Biomedical subjects

J Gooch

Publications and source records attributed to J Gooch.

At least 19 recordsLinked to original sources

Conversational skills of preschool and school-age children with cleft lip and palate.

OBJECTIVE: The purpose of this study was to examine the conversational skills of preschool and school-age children with cleft lip and palate. DESIGN: The children were audio- and videotaped during interactions with an unfamiliar adult. In addition, standardized measures of speech and language were administered, and ratings of resonance were obtained. Comparisons were made between the children with cleft lip and palate and their same-age peers on measures of conversational participation and a standardized test of pragmatic skills. PARTICIPANTS: Participants were 20 children with unilateral cleft lip and palate (10 preschoolers and 10 school-age children) recruited from the Craniofacial Team at Rainbow Babies and Children's Hospital, Cleveland (OH) and 20 noncleft peers matched for gender, age, and socioeconomic status. MAIN OUTCOME MEASURES: Separate comparisons were made for the preschool children with cleft lip and palate and their noncleft peers, and the school-age children with cleft lip and palate and their noncleft peers on eight measures of conversational assertiveness/responsiveness and the standardized tests of pragmatics. Next, each child with cleft lip and palate was classified for level of conversational participation. RESULTS: Paired t tests revealed no significant differences between the preschool and school-age children with cleft lip and palate and their noncleft peers in level of conversational participation. However, individual child comparisons revealed less assertive profiles of conversational participation for 50% of the preschool and 20% of the school-age children with cleft lip and palate. CONCLUSIONS: Children with cleft lip and palate may show a less assertive style of conversational participation, at least during the preschool years. Therefore, craniofacial team evaluations should include examination of conversational competency, particularly for children who are demonstrating difficulty with other aspects of speech, language, or social development.

Child

Primary idiopathic optic neuritis in U.S. Air Force Aviators.

The records of 31 male aviators seen at the Ophthalmology Branch of the USAF Aeromedical Consultation Service (formerly the USAF School of Aerospace Medicine) for a diagnosis of primary idiopathic optic neuritis (PION) were reviewed. Each subject received comprehensive ophthalmologic and neurologic examinations. The long-term follow-up data were collected through repeat examinations and by survey. Despite 39% of aviators being grounded due to complications of their PION or multiple sclerosis (MS), many aviators diagnosed with PION may be safely returned to flying duties. However, any aviator diagnosed with PION has a risk of recurrence or a potential to develop systemic MS and must be carefully reevaluated and followed to ensure they remain a viable asset and do not compromise flight safety or mission completion.

Adult

Childhood traumatic brain injury: neuropsychological status at the time of hospital discharge.

The present study examined the status at the time of hospital discharge of 22 children who had sustained moderate to severe closed head injuries. Despite an average length of stay of 46 days, on average the children performed significantly below normal on cognitive, memory, and motor tests. The children who did the worst were those who sustained their injuries riding in a vehicle, as opposed to being hit by a vehicle while walking or riding a bicycle. No reliable associations were found between neuroimaging data and cognitive measures; however, children whose scans showed more diffuse severe injury (e.g. white matter hemorrhages) performed more poorly than those who did not. Of further importance were detailed morphometric analyses of tissue quantity and ventricular volume that showed significantly increased ventricle to brain ratios (VBR) over a 3 to 4 week period following injury.

Anticonvulsants

Identification of the trapped calcium in the gelsolin segment 1-actin complex: implications for the role of calcium in the control of gelsolin activity.

The X-ray structure of the complex of actin with gelsolin segment 1 revealed the presence of two calcium ions, one bound at an intramolecular site within segment 1 and the other bridging the segment directly to actin. Although earlier calcium binding studies at pH 8.0 revealed only a single calcium trapped in the complex (and also in the binary gelsolin-actin complex), it is here shown that two calcium ions are bound under the conditions of crystallization at physiological pH. Mutation of acidic residues in either actin or segment 1 involved in ligation of the intermolecular calcium ion resulted in loss of one of the bound calcium ions at pH < 7, but not at pH 8. Thus the calcium ion trapped in the segment 1-actin complex is that located at the intramolecular site. The implications of this for gelsolin function are discussed.

Actins

Variant plasma gelsolin responsible for familial amyloidosis (Finnish type) has defective actin severing activity.

Familial amyloidosis, Finnish type is caused by a single base mutation in gelsolin, an actin filament severing and capping protein that is present in most tissues and in blood plasma. The mutation replaces aspartic acid with asparagine at residue 187 of the plasma sequence. This renders the gelsolin susceptible to proteolysis as a consequence of which amyloid protein is formed. Here it is shown that the mutant protein in plasma from a patient homozygous for this mutation lacks both actin severing and nucleating activities. Evidence is presented that the cleaved mutant gelsolin has dissociated under non-denaturing conditions and that the resultant 65,000 and 55,000 M(r) C-terminal fragments aggregate.

Actins

Crystallization of the complex of actin with gelsolin segment 1.

Crystals of a 1:1 complex between human gelsolin segment 1 and actin have been grown from solutions containing polyethylene glycol 6000. The crystals are orthorhombic, space group P2(1)2(1)2(1); the axes are a = 57.4 A, b = 70.4 A, c = 184.5 A. They are moderately stable to X-rays and diffract to beyond 2.5 A. There is one molecule of complex in the asymmetric unit.

Actins

Crystallization of human gelsolin.

Human gelsolin has been crystallized by microdialysis techniques to give single crystals that diffract to 3.5 A resolution. The crystals belong to space group P42(1)2 and have cell dimensions a = 175.0 A, c = 151.6 A. They contain two gelsolin molecules in the asymmetric unit.

Calcium-Binding Proteins

Identification of a region in segment 1 of gelsolin critical for actin binding.

The actin severing and capping protein gelsolin contains three distinct actin binding sites. The smallest actin binding domain of approximately 15,000 Mr was originally obtained by limited proteolysis and it corresponds to the first of six repeating segments contained in the gelsolin sequence. We have expressed this domain (here termed segment 1 or N150 to define its amino acid length) in Escherichia coli, together with a series of smaller mutants truncated at either N- or C-terminal ends, in an attempt to localize residues critical of actin binding. Limited truncation of segment 1 by 11 residues at its N-terminal end has no observable effect on actin binding, but on removal of a further eight residues, actin binding is totally eliminated. Although this loss of actin binding may reflect ablation of critical residues, we cannot rule out the possibility that removal of these residues adversely affects the folding of the polypeptide chain during renaturation. Truncation at the C-terminus of segment 1 has a progressive effect on actin binding. Unlike intact segment 1, which shows no calcium sensitivity of actin binding within the resolution of our assays, a mutant with 19 residues deleted from its C-terminus shows unchanged affinity for actin in the presence of calcium, but approximately 100-fold weaker binding in its absence. Removal of an additional five residues from the C-terminus produces a mutant that binds actin only in calcium. Further limited truncation results in progressively weaker calcium dependent binding and all binding is eliminated when a total of 29 residues has been removed. Although none of the expressed proteins on their own binds calcium, 45Ca is trapped in the complexes, including the complex between actin and segment 1 itself. These results highlight a region close to the C-terminus of segment 1 that is essential for actin binding and demonstrate that calcium plays an important role in the high affinity actin binding by this domain of gelsolin.

Actins

Loss of calcium sensitivity of plasma gelsolin is associated with the presence of calcium ions during preparation.

Gelsolin is a calcium-dependent actin severing and capping protein. Calcium 'opens' the molecule to make actin binding sites accessible, but removal of calcium from the medium does not necessarily fully reverse this process. The calcium sensitivity of actin monomer binding and actin filament severing is here shown to vary considerably with the source of gelsolin and conditions of preparation. Plasma gelsolin undergoes irreversible loss of calcium sensitivity when prepared in the presence of calcium ions. This is not due solely to effects of bound calcium, because purified human plasma gelsolin expressed in E. coli and stored in calcium shows no comparable loss of calcium sensitivity when prepared or stored in calcium. These results suggest the presence of factors in plasma which, in the presence of calcium, promote an irreversible structural change in gelsolin resulting in permanent loss of calcium sensitivity.

Actins

Expression of human plasma gelsolin in Escherichia coli and dissection of actin binding sites by segmental deletion mutagenesis.

Human plasma gelsolin has been expressed in high yield and soluble form in Escherichia coli. The protein has nucleating and severing activities identical to those of plasma gelsolin and is fully calcium sensitive in its interactions with monomeric actin. A number of deletion mutants have been expressed to explore the function of the three actin binding sites. Their design is based on the sixfold segmental repeat in the protein sequence. (These sites are located in segment 1, segments 2-3, and segments 4-6). Two mutants, S1-3 and S4-6, are equivalent to the NH2- and COOH-terminal halves of the molecule obtained by limited proteolysis. S1-3 binds two actin monomers in the presence or absence of calcium, it severs and caps filaments but does not nucleate polymerization. S4-6 binds a single actin monomer but only in calcium. These observations confirm and extend current knowledge on the properties of the two halves of gelsolin. Two novel constructs have also been studied that provide a different pairwise juxtaposition of the three sites. S2-6, which lacks the high affinity site of segment 1 (equivalent to the 14,000-Mr proteolytic fragment) and S1,4-6, which lacks segments 2-3 (the actin filament binding domain previously identified using the 28,000-Mr proteolytic fragment). S2-6 binds two actin monomers in calcium and nucleates polymerization; it associates laterally with filaments in the presence or absence of calcium and has a weak calcium-dependent fragmenting activity. S1,4-6 also binds two actin monomers in calcium and one in EGTA, has weak severing activity but does not nucleate polymerization. A model is presented for the involvement of the three binding sites in the various activities of gelsolin.

Actins

Skin hygiene.

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Baths

Skin hygiene.

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Baths

Preparation and characterization of pig plasma and platelet gelsolins.

Pig plasma gelsolin has been prepared by a revised method involving poly(ethylene glycol) precipitation, chromatography on CM-cellulose and affinity chromatography on actin-Sepharose. Pig platelet gelsolin has been prepared by chromatography on DEAE-cellulose and actin-Sepharose. Partial chemical and proteolytic cleavage shows that the two proteins are closely related in their fragmentation patterns. The amino acid sequences are identical at the N-terminus of the platelet protein, but the plasma protein has an additional nine residues on the N-terminal side of the common sequence. Calcium binding studies show that the plasma protein has similar calcium binding properties to both macrophage and platelet gelsolins.

Amino Acid Sequence

Interactions of pig plasma gelsolin with G-actin.

Pig plasma gelsolin forms a ternary complex with monomeric actin in 0.1 mM CaCl2 and a binary complex in EGTA (less than 0.01 microM calcium), as shown by gel filtration and fluorescence changes when actin which had been treated with N-ethylmaleimide and 7-chloro-4-nitrobenzeno-2-oxa-1,3-diazole (NBD-actin) or with N-(1-pyrenyl)iodoacetamide (PI-actin) binds to gelsolin. The fluorescence enhancement per actin molecule bound is similar in the binary and ternary complexes, but the affinity of gelsolin for labelled actin is very much greater in the presence of calcium. Furthermore, the formation of ternary complex exhibits strong positive cooperativity.

Actins