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Biomedical subjects

P G Gallagher

Publications and source records attributed to P G Gallagher.

At least 19 recordsLinked to original sources
PubMed1992

A common type of the spectrin alpha I 46-50a-kD peptide abnormality in hereditary elliptocytosis and pyropoikilocytosis is associated with a mutation distant from the proteolytic cleavage site. Evidence for the functional importance of the triple helical model of spectrin.

We studied nine individuals from five unrelated families with alpha I/46-50a hereditary elliptocytosis (HE) or hereditary pyropoikilocytosis (HPP), including one of the original HHP probands first reported by Zarkowsky and colleagues (1975. Br. J. Haematol. 29:537-543). Biochemical analysis of erythrocyte membrane proteins from these patients revealed, as a common abnormality, the presence of the alpha I/46-50a peptide after limited tryptic digestion of spectrin. The polymerase chain reaction was utilized to study the structure of the DNA encoding the alpha I domain of spectrin in the affected individuals. The DNA sequence of the alpha-spectrin gene encoding the region of the alpha-spectrin chain surrounding the abnormal proteolytic cleavage site was normal. We identified a point mutation causing the replacement of a highly conserved leucine residue by proline at position 207 in the alpha-spectrin chain, a site 51 residues to the amino-terminal side of the abnormal proteolytic cleavage site. Analysis of the proposed triple helical model of spectrin repeats reveals that the mutation occurs in helix 2 at a position directly opposite the abnormal proteolytic cleavage site in helix 3, making this the first report of a mutation occurring in helix 2 of a repeat in the alpha I domain of spectrin. These results add to the molecular heterogeneity of mutations associated with HE/HPP and provide further support for the proposed triple helical model of spectrin. Disruption of this proposed alpha-helical structure by helix-breaking proline substitutions may result in a functionally defective spectrin chain.

Amino Acid Sequence↗
PubMed1991

Heterogeneity of the molecular basis of hereditary pyropoikilocytosis and hereditary elliptocytosis associated with increased levels of the spectrin alpha I/74-kilodalton tryptic peptide.

Hereditary pyropoikilocytosis (HPP) and hereditary elliptocytosis are closely related, congenital disorders of the red blood cell usually associated with defective spectrin self-association and abnormal limited tryptic digestion of the N-terminal of domain of spectrin. Enhanced cleavage by trypsin of spectrin from affected individuals at arginyl residue 45* and lysyl residue 48* frequently yields increased amounts of an alpha 1/74-Kd fragment at the expense of the normal alpha 1/80-Kd parent fragment. Limited tryptic digestion of three unrelated individuals with HPP showed the alpha 1/74 defect. To ascertain the molecular defect responsible for the abnormality, the structure of exon 2 of the alpha-spectrin gene was examined. Genomic DNA from the subjects was amplified by the polymerase chain reaction using primers flanking exon 2. Restriction endonuclease digestion of amplified products showed the loss of the HindIII site at codons 47 and 48 in one allele of subject 1 and abolished the AhaII site at codons 27 and 28 in one allele of subjects 2 and 3. Nucleotide sequence analysis of subcloned amplified DNA from the HPP subjects showed three novel amino acid substitutions. In subject 1 (a black individual), a single base substitution (AAG----AGG) at codon position 48 changes amino acid residue lysine to arginine. In subject 2 (a white individual), a single base substitution (CGT----AGT) at codon 28 changes arginine to serine. In subject 3 (a black individual), a different base substitution at position 28 (CGT----CTT) changes arginine to leucine. These mutations occur at positions of the alpha l domain where other mutations have also been described, indicating that the normal residues at these positions play an important role in spectrin dimer self-association and thus, in membrane stability.

Adolescent↗
PubMed1991

A splice site mutation of the beta-spectrin gene causing exon skipping in hereditary elliptocytosis associated with a truncated beta-spectrin chain.

We studied a French kindred with hereditary elliptocytosis associated with a spectrin variant (spectrin LePuy) containing a beta-spectrin chain that is truncated at its C terminus (Dhermy, D., Lecomte, M., Garbarz, M., Bournier, O., Galand, C., Gautero, H., Feo, C., Alloisio, N., Delaunay, J., and Boivin, P. (1982) J. Clin. Invest. 70, 707-715). The structure of the 3' end of the beta-spectrin gene, the region encoding the C terminus of beta-spectrin, was determined. Nucleotide sequencing of amplified genomic DNA revealed a mutation at position +4 (A----G) of the 5' donor consensus splice site of the intron following the third-to-last exon (exon X) in one beta-spectrin allele of a heterozygous patient. Agarose gel electrophoresis of polymerase chain reaction-amplified cDNA revealed an extra band of lower molecular weight, suggesting that the shortened beta-spectrin chain of spectrin LePuy arises from aberrant mRNA splicing. Nucleotide sequencing of the shorter cDNA amplification product revealed that the sequences encoding exon X were absent. Southern blotting of cDNA amplification products confirmed this result. The skipping of exon X causes a shift in the normal reading frame resulting in the encoding of a new amino acid sequence at the C terminus of the mutant beta-spectrin chain. A new in-frame stop codon is encountered following a single residue of this novel sequence.

Amino Acid Sequence↗
PubMed1991

An insertional frameshift mutation of the beta-spectrin gene associated with elliptocytosis in spectrin nice (beta 220/216).

Spectrin Nice (beta 220/216) is a spectrin variant associated with a shortened beta chain found in a patient with elliptocytosis. The shortened beta chain (beta' chain) appeared as an additional band of approximately 216 Kd on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was defective in its ability to be phosphorylated. There were increased amounts of spectrin dimers in crude spectrin extracts from the propositus and the association constant of spectrin dimer self-association was decreased. There was an associated increase of the alpha I 74-Kd fragment from the alpha chain after partial trypic digestion of spectrin. To identify the underlying molecular defect, we analyzed cDNA for beta spectrin obtained by polymerase chain reaction amplification of reverse-transcribed reticulocyte messenger RNA from peripheral blood of the propositus. DNA sequencing of individual as well as pooled subclones showed that two extra bases (GA) are inserted in codon no. 2046 in one allele of the beta-spectrin gene. The insertion results in a frameshift mutation and generates an aberrant C-terminus truncated by about 4 Kd, consistent with the estimated size of the beta' chain observed. By allele-specific oligonucleotide hybridization, the insertion was shown to be present in the propositus and absent in his parents, confirming a previous proposal that it is a de novo mutation. The determination of the location of the mutation in spectrin Nice points to specific regions of the beta-spectrin chain where phosphorylation may occur. A model is proposed to describe the interaction between the alpha- and beta-spectrin chains and to explain the effects of the mutation found in spectrin Nice on the trypsin digestion pattern of its associated alpha chain.

Adolescent↗
PubMed1991

Cerebral infarctions due to CNS infection with Enterobacter sakazakii.

Recent reports have implicated Enterobacter sakazakii, a gram-negative enteric bacillus, in neonatal sepsis and meningitis. Cases of severe central nervous system involvement, including ventriculitis, brain abscess, infarction, and cyst formation, have been described. We present serial head CT findings in a case of neonatal E. sakazakii meningitis complicated by a ring enhancing cerebral infarction which mimicked abscess formation. In meningitis secondary to this agent, a recognized pattern of cerebral hypodensity with or without cystic degeneration late in the course of the infection is likely to represent cerebral infarction rather than an abscess especially if there is a lack of culture evidence of a bacterial infection.

Brain↗
PubMed1991

An approach to the diagnosis and treatment of membranous laryngotracheobronchitis in infants and children.

The purpose of this study is to report 18 cases of membranous laryngotracheobronchitis (MLTB) and to review 143 published cases in order to accurately characterize the epidemiology, presentation, clinical course, treatment, and outcome of patients with this disorder. The male:female ratio was 2:1; mean age was four years. Most patients presented with acute onset of respiratory distress with fever, toxicity, and stridor after a prodrome of upper respiratory tract infection lasting a few days. White blood cell counts varied over a wide range, and blood culture results were rarely positive. Respiratory cultures commonly yielded Staphylococcus aureus or Haemophilus influenzae. Diagnosis was usually confirmed by airway radiographs or endoscopy. An artificial airway was required in 83% of patients. Complications included respiratory failure, toxic shock syndrome, anoxic encephalopathy, and death. MLTB is a serious, potentially fatal cause of acute infectious airway obstruction in infants and children that requires an organized approach to diagnosis and management.

Acute Disease↗
PubMed1991

Sclerotherapy.

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History, 20th Century↗
PubMed1991

Spectrin Rouen (beta 220-218), a novel shortened beta-chain variant in a kindred with hereditary elliptocytosis. Characterization of the molecular defect as exon skipping due to a splice site mutation.

The molecular defect responsible for the shortened beta-spectrin chain variant, spectrin Rouen, was identified by analysis of cDNA and genomic DNA of affected individuals after amplification by the polymerase chain reaction. Peripheral blood reticulocyte RNA was transcribed into cDNA and amplified using primers corresponding to the 3' end of beta-spectrin cDNA. Agarose gel electrophoresis of cDNA amplification products from affected individuals revealed the expected band of 391 bp as well as a shortened band of 341 bp. Nucleotide sequencing of the shortened cDNA amplification product revealed that the sequences corresponding to the penultimate exon of the beta-spectrin gene (exon Y) were absent. This result was confirmed by hybridization of a Southern blot of amplification products with a labeled probe specific for exon Y. Nucleotide sequencing of the proband's amplified genomic DNA corresponding to this region of the beta-spectrin gene revealed a mutation in the 5' donor consensus splice site of the intron downstream of the Y exon, TGG/GTGAGT to TGG/GTTAGT, in one allele. We postulate that this mutation leads to the splicing out or skipping of exon Y, thus producing a shortened beta-spectrin chain. To our knowledge, this is the first documented example of exon skipping as the cause of a shortened beta-spectrin chain in a case of hereditary elliptocytosis. The exon skip results in the loss of the 17 amino acids of exon Y and creates a frameshift with the synthesis of 33 novel amino acids prior to premature chain termination 14 residues upstream of the normal carboxy terminus of the beta-spectrin chain, giving a mutant beta-spectrin chain that is 31 amino acids shorter than the normal chain.

Amino Acid Sequence↗
PubMed1988

Listeria monocytogenes endocarditis: a review of the literature 1950-1986.

34 cases of Listeria monocytogenes endocarditis reported in the literature from 1950-1986 were reviewed. The male to female ratio was 2: 1. The average age was 49 years, and 35% of patients were 60 years of age or older. A single case of polymicrobial endocarditis was identified. There were 8 cases of prosthetic valve endocarditis. Left-sided cardiac involvement predominated, with only a single case of right-sided endocarditis reported. Aortic and mitral valvular involvement accounted for 32 and 29% of cases respectively. Underlying cardiac disease was present in over half of the cases, with rheumatic heart disease being the most common underlying cardiac condition. Noncardiac underlying conditions were found in 38% of cases. These included chronic hemodialysis, alcoholism, pregnancy, malignancies, diabetes mellitus, steroid therapy and malnutrition. Onset of the disease was varied as was initial presentation. There was a high incidence of vascular phenomena (59%), with large vessel emboli seen late in the course of many cases. Many cases were diagnosed late. Overall mortality was 50%. Treatment of listeria endocarditis varied from case to case. A review of in vitro and in vivo studies as well as case reports suggests that ampicillin or penicillin plus an aminoglycoside may be the treatment of choice.

Adolescent↗
PubMed1985

Group B streptococcal bacteremia in a community teaching hospital.

Group B streptococcal bacteremia outside the perinatal setting is not commonly emphasized. This report reviews all episodes of group B streptococcal bacteremia during a four and a half year period in a large community teaching hospital. Fourteen episodes occurred in neonates, four in parturient women, and 28 in other adults. Bacteremic adults were usually elderly with an average age of 68 years. Group B streptococcal bacteremia occurred in adults with various underlying diseases, including diabetes mellitus, liver disease, peripheral vascular disease, and hematologic disease, and in those receiving long-term steroid therapy. Infections causing group B streptococcal bacteremia in adults included decubitus ulcers, pneumonia, endocarditis, cellulitis, arthritis, osteomyelitis, and meningitis. Thirteen of 28 episodes of group B streptococcal bacteremia in adults were hospital-acquired. Overall mortality in adults was 70 percent. Group B streptococcal bacteremia in adults outside of the perinatal setting is associated with significant underlying diseases and has a high mortality.

Adolescent↗