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Biomedical subjects

D Ring

Publications and source records attributed to D Ring.

68 records · Page 4Linked to original sources
PubMed1984

The spark discharge synthesis of amino acids from various hydrocarbons.

The spark discharge synthesis of amino acids using an atmosphere of CH4 + N2 + H2O + NH3 has been investigated with variable pNH3. The amino acids produced using higher hydrocarbons (ethane, ethylene, acetylene, propane, butane, and isobutane) instead of CH4 were also investigated. There was considerable range in the absolute yields of amino acids, but the yields relative to glycine (or alpha-amino-n-butyric acid) were more uniform. The relative yields of the C3 to C6 aliphatic alpha-amino acids are nearly the same (with a few exceptions) with all the hydrocarbons. The glycine yields are more variable. The precursors to the C3-C6 aliphatic amino acids seem to be produced in the same process, which is separate from the synthesis of glycine precursors. It may be possible to use these relative yields as a signature for a spark discharge synthesis provided corrections can be made for subsequent decomposition events (e.g. in the Murchison meteorite).

Acetylene↗
PubMed1984

Carrier detection in the testicular feminisation syndrome: deficient 5 alpha-dihydrotestosterone binding in cultured skin fibroblasts from the mothers of patients with complete androgen insensitivity.

Specific binding of 5 alpha-dihydrotestosterone (androgen receptor activity) could not be detected in cultured genital skin fibroblasts (GSF) from two patients with complete androgen insensitivity (CAI). In GSF from the mother of one patient, androgen receptor activity (8.5 fmol/mg cell protein) was reduced in comparison with controls (34.0 +/- 10.1 (SD) fmol/mg protein n = 15). These results favour X linked inheritance of CAI and X inactivation at the androgen receptor locus. Androgen receptors were not detected in GSF of the second mother. It appears that female carriers of CAI could be detected by decreased 5 alpha-dihydrotestosterone binding in GSF. Androgen receptor activity was also undetectable in non-genital skin fibroblasts (NGSF) from the second mother and two further CAI patients. However, in 1 in 10 control NGSF lines androgen receptor activity was at the lower limit of assay sensitivity (1 to 2 fmol/mg protein) demonstrating that NGSF may not be reliable for family studies of androgen receptor deficiency.

Adult↗
PubMed1984

Partial androgen insensitivity as a cause of genital maldevelopment.

A newborn with ambiguous genitalia appeared to have male pseudohermaphroditism caused by partial insensitivity to androgens associated with a subnormal level of androgen receptors in cultured genital skin fibroblasts. This hitherto infrequently diagnosed condition has genetical and prognostic implications regarding fertility. The causes of male pseudohermaphroditism and the repercussions of partial androgen insensitivity are discussed.

Androgens↗
PubMed1983

Close contacts between H1 histone molecules in nuclei.

H1 histone homodimer has been purified from nuclei treated with either long (dimethylsuberimidate, dimethyl dithiobisproprionimidate) or short (ethyl dimethylaminocarbodiimide) cross-linking reagents. When such H1 dimers were cleaved with N-bromosuccinimide, chymotrypsin, or staphylococcal protease, analysis of the resulting fragments suggests that the major cross-links were formed between the COOH-terminal portions of neighboring H1 molecules, and that substantial bridging can also be made between the NH2-terminal portion of one H1 molecule and the COOH-terminal portion of another. NH2-terminal to NH2-terminal cross-links were not seen at significant levels, suggesting that the position of the NH2-terminal portion of H1 in chromatin is more restricted.

Amino Acid Sequence↗
PubMed1982

Mitosis in a cell with multiple centrioles.

N115 mouse neuroblastoma cells possess a large number of microtubule organizing centers (MTOCs) which can be identified ultrastructurally as single centrioles. The distribution and activity of these organizing centers can be followed through all stages of the cell cycle by labeling microtubules with anti-tubulin and chromatin with the Hoechst dye, Bisbenzimid. We have found that multiple MTOCs persist and continue to organize microtubules during mitosis. They exhibit a well-defined sequence of movements, starting from a loose cluster during interphase, proceeding to a widely and evenly dispersed arrangement in prophase, gathering into small clusters and chains during prometaphase, and residing in two ring-shaped groups at the mitotic poles during metaphase and anaphase. Despite their large number of centrioles, virtually all N115 cells show a normal bipolar mitosis, but often with unequal numbers of centrioles at the two poles. Such observations bring into question the importance of the centriole in establishing bipolar division in this cell type.

Animals↗
PubMed1979

Chemical cross-linking of H1 histone to the nucleosomal histones.

When whole steer kidney nuclei were treated with dimethyl-3,3'-dithiobisproprionimidate, N,N'-bis(2-carboxyimidomethyl) tartaramide dimethyl ester, or 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide under approximately physiological ionic conditions, H1 histone was cross-linked to each of the four histones in the nucleosome core. The carbodiimide reagent, which introduces no atoms between the amino acid side chains being joined, seemed to give the same result as did the longer di-imidate cross-linking reagents. When conditions were optimized for the production of of H1-containing dimers, the total yield of H1-core histone heterodimers was nearly equal to the yield of H1 homodimers. Naturally occurring H1 dimers and cross-linked heterodimers of high mobility group proteins 14 and 17 with H1 and core histones were also observed.

Animals↗
PubMed1972

Prebiotic synthesis of hydrophobic and protein amino acids.

The formation of amino acids by the action of electric discharges on a mixture of methane, nitrogen, and water with traces of ammonia was studied in detail. The presence of glycine, alanine, alpha-amino-n-butyric acid, alpha-aminoisobutyric acid, valine, norvaline, isovaline, leucine, isoleucine, alloisoleucine, norleucine, proline, aspartic acid, glutamic acid, serine, threonine, allothreonine, alpha-hydroxy-gamma-aminobutyric acid, and alpha,gamma-diaminobutyric acid was confirmed by ion-exchange chromatography and gas chromatography-mass spectrometry. All of the primary alpha-amino acids found in the Murchison Meteorite have been synthesized by this electric discharge experiment.

Alanine↗
PubMedDate not supplied

The use of a blade plate and autogenous cancellous bone graft in the treatment of ununited fractures of the proximal humerus.

Stable internal fixation is essential to obtain healing of an ununited fracture of the proximal humerus. Standard plate and screw fixation may be inadequate to secure a small, osteopenic proximal fragment. We used blade plates and autogenous cancellous bone graft to repair ununited fractures of the proximal humerus in 25 patients (19 women and 6 men) with a mean age of 61 years. Healing was documented in 23 of 25 patients (92%). Objective and subjective instruments documented substantial functional improvement in patients with healed fractures. The results were classified as good or excellent in 20 of 25 patients, and few complications were encountered. Blade plate fixation facilitates successful treatment of ununited fractures of the proximal humerus.

Adult↗
PubMedDate not supplied

Pyogenic infectious spondylitis in children: the convergence of discitis and vertebral osteomyelitis.

The outcomes of 47 patients, ranging in age from 7 months to 15 years, 8 months (average, 4 years, 8 months) with presumed pyogenic infectious spondylitis (so-called discitis) were evaluated retrospectively with regard to duration and recurrence of symptoms, and the need for readmission, retreatment, or surgical intervention. Among nonimmobilized patients, 18% (four of 22) receiving intravenous antibiotics, 50% (five of 10) receiving oral antibiotics, and 67% (four of six) receiving no antibiotics (analgesics and bed rest only) had either prolonged or recurrent symptoms or both. Among patients treated with spinal immobilization, one of five receiving concomitant intravenous antibiotics and two of two receiving no antibiotics had a recurrence of symptoms following discontinuation of immobilization. Two patients required surgical drainage of paraspinal abscesses (one cervical and one lumbar). These findings support the contention that so-called discitis is simply pyogenic infectious spondylitis in children and suggest that specific treatment with intravenous antibiotics is more likely to lead to rapid relief of symptoms and signs without recurrence.

Administration, Oral↗
PubMedDate not supplied

Monteggia fractures in children and adults.

The eponymous term "Monteggia fracture" is most precisely used to refer to dislocation of the proximal radioulnar joint in association with a forearm fracture. It is the character of the ulnar fracture, rather than the direction of radial head dislocation, that is useful in determining the optimal treatment of Monteggia fractures in both children and adults. Stable anatomic reduction of the ulnar fracture results in anatomic reduction of the radial head. The notoriously poor results of treatment of Monteggia fractures in adults improved dramatically after the development of modern techniques of plate-and-screw fixation, which facilitate early mobilization by ensuring anatomic reduction. The relatively good results associated with nonoperative treatment of pediatric Monteggia injuries reflect the prevalence of stable (incomplete) fractures in children. Unstable (complete) ulnar fractures are prone to residual or recurrent displacement and may require operative fixation. Late reconstruction of chronic Monteggia lesions in children can be complicated and unpredictable. The key to a good outcome after a Monteggia-type fracture-dislocation of the forearm remains early recognition of proximal radioulnar dissociation.

Adult↗
PubMedDate not supplied

Acute fractures of the scaphoid.

Nondisplaced fractures of the scaphoid heal with cast immobilization in most cases, but operative treatment is being offered with greater frequency to active patients as an approach to reduce the period of cast immobilization. Computed tomography is more useful for evaluating displacement than standard radiography. Displaced fractures are at greater risk for nonunion and malunion-both of which have been associated with the development of radiocarpal arthritis in long-term studies--and should therefore be treated operatively. Surgical treatment is also recommended for complex fractures (open fractures, perilunate fracture-dislocations, and scaphoid fractures associated with fracture of the distal radius), very proximal fractures, and fractures for which the diagnosis and treatment have been delayed. Operative treatment of fractures of the scaphoid has been simplified by the development of cannulated screws. Internal fixation of fractures of the scaphoid may offer some advantages, including earlier return to athletics or manual labor.

Acute Disease↗
PubMedDate not supplied

Pediatric floating elbow.

SUMMARY: A retrospective review of 16 patients with floating elbow injuries over a 9-year period at a tertiary care children's hospital confirms that these injuries are associated with substantial swelling and the potential to develop compartment syndrome, particularly when circumferential cast immobilization is used. Among 10 patients in whom the forearm was treated with closed reduction and plaster immobilization, a compartment syndrome developed in 2, and 4 patients had incipient compartment syndrome that responded to splitting of the cast; 3 of these subsequently required remanipulation of the distal radius. One patient with compartment syndrome had Volkmann ischemic contracture. Six patients underwent stabilization of both the distal humeral and forearm fractures with percutaneously inserted Kirschner wires, thereby allowing postreduction immobilization in a split cast. None of these patients had problems with excessive swelling or compartment syndrome. Percutaneous Kirschner wire fixation of both the humeral and forearm fractures in pediatric floating elbow injuries allows noncircumferential immobilization, thereby reducing the risk of compartment syndrome.

Adolescent↗