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Biomedical subjects

J G Hall

Publications and source records attributed to J G Hall.

At least 109 records · Page 6Linked to original sources
PubMed1990

How imprinting is relevant to human disease.

Genomic imprinting appears to be a ubiquitous process in mammals involving many chromosome segments whose affects are dependent on their parental origin. One of the challenges for clinical geneticists is to determine which disorders are manifesting imprinting effects and which families are affected. Re-evaluation of cases of chromosomal abnormalities and family histories of disease manifestations should give important clues. Examination of the regions of human chromosomes homologous to mouse imprinted chromosomal regions may yield useful information. Cases of discordance in monozygous twins may also provide important insights into imprinted modification of diseases.

Animals↗
PubMed1990

A retrospective study of pregnancy complications among 828 cases of arthrogryposis.

828 cases with multiple congenital contractures (arthrogryposis) were categorized and histories were reviewed to identify pregnancy complications. 53.0% of cases had a specified diagnosis or known cause and no diagnosis was found for 47.0% of which 27.2% were though to probably have a genetic basis and 19.8% were of unknown etiology. Our data provides no evidence to support the suggestion that arthrogryposis is frequently a result of environmental or structural causes including uterine structural anomaly, intra-uterine infection, etc. Normal frequencies of bleeding, hormone treatment during gestation, amniotic fluid leakage, uterine anomaly, maternal illness, and maternal and paternal age were noted. Apparent, increased frequencies of twinning, severe nausea, polyhydramnios and oligohydramnios were observed. In particular, the frequency of polyhydramnios was dramatically increased among lethal cases (vs survivors) and thus, polyhydramnios appears to be a poor prognostic sign when associated with decreased fetal movement. Large case control studies with complete pregnancy histories are needed to confirm these results and to definitively identify pregnancy complications that are useful "flags" to indicate decreased fetal movement in utero and thus, aid in the identification of primary causes of arthrogryposis.

Arthrogryposis↗
PubMed1989

Interaction of the antitumour antibiotic luzopeptin with the hexanucleotide duplex d(5'-GCATGC)2. One-dimensional and two-dimensional n.m.r. studies.

1H- and 31P-n.m.r. spectroscopy were used to characterize the solution structure of the 1:1 complex formed between the antitumour antibiotic luzopeptin and the self-complementary hexanucleotide d(5'-GCATGC)2. Eighteen nuclear Overhauser effects between antibiotic and nucleotide protons, together with ring-current-induced perturbations to base-pair and quinoline 1H resonances, define the position and orientation of the bound drug molecule. Luzopeptin binds in the minor groove of the DNA with full retention of dyad symmetry, its quinoline chromophores intercalating at the 5'-CpA and 5'-TpG steps and its depsipeptide ring spanning the central two A.T base-pairs. The chromophores stack principally on the adenine base with their carbocyclic rings pointing towards the deoxyribose of the cytosine. There is no evidence for Hoogsteen base-pairing in the complex, all glycosidic bond angles and sugar puckers being typical of B-DNA as found for the free hexanucleotide. The 'breathing' motions of the A.T and internal G.C base-pairs are substantially slowed in the complex compared with the free DNA, and the observation that two phosphate resonances are shifted downfield by at least 0.5 p.p.m. in the 31P-n.m.r. spectrum of the complex suggests pronounced local helix unwinding at the intercalation sites. The data are consistent with a model of the complex in which luzopeptin bisintercalates with its depsipeptide essentially in the conformation found in the crystal of the free antibiotic [Arnold & Clardy (1981) J. Am. Chem. Soc. 103, 1243-1244]. We postulate only one conformational change within the peptide ring, which involves rotation of the pyridazine-glycine amide group linkage by 90 degrees towards the DNA surface. This manoeuvre breaks the glycine-to-glycine transannular hydrogen bonds and enables the glycine NH groups to bond to the thymine O-2 atoms of the sandwiched A.T base-pairs. It also shortens the major axis of the depsipeptide so that the interchromophore distance is more suitable for spanning two base-pairs. The model further implies that the carboxy and hydroxy groups of the L-beta-hydroxyvaline residue are appropriately positioned for hydrogen-bonding to the 2-amino group of guanine and the O-2 atom of cytosine of the adjacent G.C base-pair.

Antibiotics, Antineoplastic↗
PubMed1989

Joubert's syndrome associated with congenital ocular fibrosis and histidinemia.

We describe a 16-month-old girl with Joubert's syndrome (JS), congenital ocular fibrosis, and histidinemia. Abnormal respiration, ptosis, and minimal eye movements were observed in the neonatal period. Intraoperative examination of the eyes later demonstrated severely restricted eye movements and abnormal insertions and fibrosis of the extraocular muscles. Computed tomography of the head revealed absence of the corpus callosum and brain stem. Histidine levels were elevated in the blood, urine, and cerebrospinal fluid. The patient was ataxic and developmentally delayed. To our knowledge, the association of JS with congenital ocular fibrosis has not previously been described. This report indicates that jerky eye movements are not an invariable finding in JS.

Ataxia↗
PubMed1989

Congenital diaphragmatic hernia, coarse facies, and acral hypoplasia: Fryns syndrome.

We describe five patients with Fryns syndrome. Four presented with diaphragmatic hernia and died in the neonatal period. One did not have diaphragmatic involvement and survived but is severely mentally retarded. All patients had "coarse" faces, microretrognathia, macrostomia, and distal digital hypoplasia. In addition to previously reported traits, our patients had clinical manifestations that have not previously been described, including omphalocele, broad clavicles, Hirschsprung "disease," and anal anomalies. The condition was detected antenatally in three of the cases. The patients include two sib pairs, further supporting autosomal recessive inheritance.

Abnormalities, Multiple↗
PubMed1989

Congenital shortness of the costocoracoid ligament.

We report a large kindred in which individuals presented with fixation of the scapula to the first rib by a congenitally short costocoracoid ligament. Cosmetic deformity with rounding of the shoulder and loss of the anterior clavicular contour was the main concern of the affected individuals. Movements requiring rotation or retraction of the scapula were limited, although this did not interfere with normal activities. Surgical treatment consists of excision of the costocoracoid ligament and resulted in some correction of the cosmetic deformity. The pedigree supports an autosomal dominant mode of inheritance with variable expression. The abnormality results in a pectoral girdle which is reminiscent of that seen in the monotremes.

Adult↗
PubMed1989

Failure to find differences in drinking behavior as a function of familial risk for alcoholism: a replication.

Groups of high-risk (alcoholic fathers), middle-risk (second-degree alcoholic relatives) and low-risk (no first- or second-degree alcoholic relatives) male college students were compared with respect to drinking behavior, sociodemographic variables, personality, cognitive functioning, and mental health and drug use problems in themselves and in family members. The groups differed significantly on only one of a number of sociodemographic variables. No significant group differences were revealed in drinking behavior, or alcohol-related symptoms or consequences. High-risk subjects reported significantly more childhood attentional and social problems than did low-risk subjects. No group differences were found with respect to other childhood problem behaviors, cognitive functioning, subject or family drug use, or mental health problems. The findings are discussed in terms of the questions they raise concerning the results of high-risk studies and the contribution of genetic factors to alcoholism.

Adolescent↗
PubMed1989

Protein fragments as probes in the study of protein folding mechanisms: differential effects of dihydrofolate reductase fragments on the refolding of the intact protein.

We describe an approach for investigating the protein folding process, using protein fragments as inhibitory probes of the refolding protein. The refolding of Escherichia coli dihydrofolate reductase (EC 1.5.1.3), reversibly unfolded in 7 M urea, was monitored by the reappearance of enzyme activity after diluting the unfolded enzyme into low urea concentrations (less than or equal to 2 M) in the presence of substrates. Of eight protein fragments produced by limited proteolysis of the 159-residue enzyme, three isolated peptides--Ser-49/Glu-90, Ile-91/Glu-154, and Gln-102/Glu-154--were evaluated for their effects on the recovery of the refolding protein's enzymatic activity. By this criterion, 13 microM peptide Gln-102/Glu-154 inhibits the refolding of 0.015 microM enzyme by approximately 80%, while the related peptide, Ile-91/Glu-154, and peptide Ser-49/Glu-90 at the same concentration inhibit the recoverable activity of the refolding enzyme by less than or equal to 20%. None of these three peptides has any significant effect on the activity of the folded enzyme. Our results indicate that peptides may inhibit refolding differentially and that these effects may be extremely sensitive to fragment sequence and composition. We suggest that peptide specificity in the inhibition of protein folding may be exploited as a structural probe of protein folding mechanisms.

Electrophoresis, Polyacrylamide Gel↗
PubMed1989

Perinatal and first year follow-up of patients with Prader-Willi syndrome: normal size of hands and feet.

Four patients with Prader-Willi syndrome, diagnosed in the neonatal period and followed during the first year of life, are reported. There were three males and one female. All four patients presented with hypotonia and distinct craniofacial dysmorphism. Prometaphase chromosome analysis showed interstitial deletion of 15q in all of them. The placentae and umbilical cords were examined in three of the patients and found normal. Electromyography done in the neonatal period suggested primary myopathy. Height, weight and head circumference were normal at birth in all patients. Hand and foot measurements showed normal size at birth and during the first year of life.

Anthropometry↗
PubMed1989

Didemnin B. Conformation and dynamics of an antitumour and antiviral depsipeptide studied in solution by 1H and 13C. n.m.r. spectroscopy.

The solution conformation of didemnin B, the most potent member of a family of depsipeptides that shows antitumour, antiviral, and immunosuppressive activity, has been studied in chloroform solution using n.m.r. spectroscopy. 1H and 13C spectra have been assigned from analysis of a number of two-dimensional homonuclear and heteronuclear chemical shift correlation experiments which confirm the recently corrected primary structure of the molecule. The conformation of the peptide has been deduced from measurements of the temperature dependence of the NH chemical shifts, analysis of coupling constant data and primarily through NOE effects observed in the rotating frame. Interproton distance bounds determined from a quantitative analysis of the ROE data provide 41 constraints from which a family of closely related structures were calculated using distance geometry algorithms. A type II beta-turn involving residues Thr6, Leu7, and Pro8 is well represented in the computed conformers as is a hydrogen bonding interaction between the NH of Leu3 and the carbonyl oxygen of Thr6. This latter interaction causes the linear portion of the structure to fold back over the depsipeptide ring, imparting to it a degree of structural stability as well as giving the molecule a somewhat globular character. Only one transannular hydrogen bond, between Ist1 NH and Leu3 carbonyl, stabilizes the conformation of the depsipeptide, which has an irregular non-planar configuration. The small temperature coefficients (less than 2.0 x 10(-3) ppm/degrees C) for the NHs of Ist1 and Leu3 are consistent with their involvement in these hydrogen bonding interactions. We find that many of the structural features observed in the crystalline form of didemnin B are conserved in solution. Analysis of the 13C spin-lattice relaxation rates of the protonated carbons reveals small variations in effective correlation times at specific sites in the molecule. The data suggests that the peptide segment encompassing residues Leu3 through to Thr6 is in a more motionally restricted part of the structure.

Amino Acid Sequence↗
PubMed1989

Chromosome maps of man and mouse. IV.

Current knowledge of man-mouse genetic homology is presented in the form of chromosomal displays, tables and a grid, which show locations of the 322 loci now assigned to chromosomes in both species, as well as 12 DNA segments not yet associated with gene loci. At least 50 conserved autosomal segments with two or more loci have been identified, twelve of which are over 20 cM long in the mouse, as well as five conserved segments on the X chromosome. All human and mouse chromosomes now have conserved regions; human 17 still shows the least evidence of rearrangement, with a single long conserved segment which apparently spans the centromere. The loci include 102 which are known to be associated with human hereditary disease; these are listed separately. Human parental effects which may well be the result of genomic imprinting are reviewed and the location of the factors concerned displayed in relation to mouse chromosomal regions which have been implicated in imprinting phenomena.

Animals↗
PubMed1989

Effects of social drinking and familial alcoholism risk on cognitive functioning: null findings.

The effects of both heavy social drinking and high familial alcoholism risk status on the cognitive performance of college men were examined in this study. A two by three factorial design was employed represented by two social drinking groups (heavy/nonheavy) and three familial risk groups (high, middle, and low). The cognitive performance tasks employed--group embedded figures, revised Beta mazes, mirror tracing, and symbol-digit paired associate learning--had all been previously shown to present difficulties to male alcoholics. No evidence was obtained of a relationship between heavy drinking or familial risk and cognitive functioning, nor a meaningful interaction of these two independent variables. Little evidence was revealed for the "hangover hypothesis" as evidenced by a relationship between drinking behavior within the past week and cognitive performance. The findings are discussed in the context of previous findings in these areas and the general difficulties of interpretation posed in nonexperimental research based on subject variables.

Adolescent↗
PubMed1989

Drug competition for thyroxine binding to transthyretin (prealbumin): comparison with effects on thyroxine-binding globulin.

We examined the effect of 26 drugs on T4 binding to transthyretin (TTR; prealbumin) and T4-binding globulin (TBG) by determining their ability to inhibit [125I]T4 binding to TTR isolated from normal human plasma and to serum diluted 1:10,000, respectively. The hierarchies for drug inhibition of T4 binding differed greatly for these two proteins. Relative to T4, the drugs were much more potent inhibitors of [125I]T4 binding to TTR than to TBG. Compounds of the anthranilic acid class, such as flufenamic, meclofenamic, and mefenamic acids, interacted particularly strongly with TTR. Flufenamic acid was more potent than T4 itself in inhibiting [125I]T4 binding [175 +/- 17% (+/- SD); cf. T4; n = 3; P less than 0.001], while mefenamic acid, diflunisal, and meclofenamic acid were 20-26% as potent as T4 in their interaction with TTR. The reactivity of diclofenac, fenclofenac, indomethacin, sulindac, and the diuretic ethacrynic acid was 0.8-2.1% relative to that of T4. In contrast, furosemide, the drug most highly reactive with TBG, was only 0.11 +/- 0.03% (n = 7) as potent as T4, followed by meclofenamic acid greater than mefenamic acid greater than fenclofenac greater than flufenamic acid greater than diflunisal greater than milrinone. Aspirin and sodium salicylate were, respectively, 0.05% and 0.20% as active as unlabeled T4 as inhibitors of [125I]T4 binding to TTR, but these compounds had only 3-4 x 10(-6)% of the activity of T4 for TBG binding. Diphenylhydantoin had no detectable effect on T4 binding to TTR and was 2.9 x 10(-4)% as reactive as T4 with TBG. Amiodarone did not interact with either binding site. Drug interactions with TTR may be important when this protein becomes a major circulating T4-binding protein, as in patients with complete or partial TBG deficiency, or when serum T4 is markedly elevated. Such interactions may also be important where TTR is the dominant tissue T4-binding protein, as in the choroid plexus. In addition, the drug competitors described here may be useful as probes to further define the structural basis for specific ligand interactions with different classes of T4-binding sites.

Binding Sites↗
PubMed1989

Arthrogryposis.

Arthrogryposis (multiple congenital contractures) has various causes and appears as many different syndromes. The basic classification for therapeutic and prognostic purposes divides affected children into those who have only limb involvement, those with limb and trunk, craniofacial or visceral involvement, and those with severe central nervous system dysfunction. Decreased fetal movement is an important etiologic factor. A multidisciplinary approach is required to evaluate these children, and early physical therapy is essential.

Arthrogryposis↗
PubMed1989

Encephalocraniocutaneous lipomatosis. Report of two cases and a review of the literature.

We describe 2 patients with unilateral facial and cerebral malformations consistent with encephalocraniocutaneous lipomatosis. The characteristic facial appearance seems to develop with age, possibly as a consequence of increased intracranial pressure. However, the clinical data suggest that this condition arises as a result of a disruption of cephalic neural crest and anterior neural tube.

Adolescent↗