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Biomedical subjects

D Becker

Publications and source records attributed to D Becker.

At least 253 records · Page 14Linked to original sources
PubMed1989

Multiple genes are transcribed in Hordeum vulgare and Zea mays that carry the DNA binding domain of the myb oncoproteins.

cDNA clones were isolated from tissue specific cDNA libraries of barley and maize using as a probe the cDNA of the maize gene C1, a regulator of anthocyanin gene expression. C1-related homology for all of the four cDNAs characterized by sequence analysis is restricted to the N-terminal 120 amino acids of the putative proteins. This region shows striking homology to the N-proximal domain of the myb oncoproteins from vertebrates and invertebrates. Within the myb proto-oncogene family this part of the respective gene products functions as a DNA binding domain. Acidic domains are present in the C-proximal protein segments. Conservation of these sequences, together with the genetically defined regulator function of the C1 gene product, suggest that myb-related plant genes code for trans-acting factors which regulate gene expression in a given biosynthetic pathway.

Amino Acid Sequence↗
PubMed1989

Loss of heterozygosity at chromosomal regions 3p and 13q in non-small-cell carcinoma of the lung represents low-frequency events.

It was recently reported that loss of heterozygosity occurred at the chromosomal region 3p in small-cell as well as in non-small-cell carcinoma of the lung. A recent report also indicated genetic changes involving sequences on chromosomes 13q and 17p in small-cell and in non-small-cell carcinomas. In the present study normal and tumor DNAs representing mostly adeno-and squamous cell carcinomas of the lung were examined for loss of heterozygosity on chromosomes 3p, 13q, 11p, and 1p. With the exception of two non-small-cell carcinomas which demonstrated loss of alleles on chromosome 3p and one small-cell carcinoma which demonstrated loss of heterozygosity at chromosome 3p as well as at 13q, evidence for loss of alleles on chromosomes 3p, 13q, 11p, and 1p could not be obtained in greater than 75% of the non-small-cell carcinoma DNAs tested. Given this result it appears unlikely that a recessive gene is located on either chromosome 3p or 13q in the majority of non-small-cell carcinomas of the lung.

Alleles↗
PubMed1988

Thiol peroxyl radical formation from the reaction of cysteine thiyl radical with molecular oxygen: an ESR investigation.

Using Electron Spin Resonance (ESR) spectroscopy, we have identified the cysteine thiol peroxyl radical (CysSOO.) at low temperatures in two aqueous glasses. This radical shows a typical peroxyl radical ESR spectrum, but unlike carbon-based peroxyl radicals has a violet color (lambda max = 540 nm) and forms a new radical showing a singlet ESR spectrum when photobleached with visible light. The cysteine peroxyl radical reacts to form the cysteine sulfinyl radical (CysSO.) in the glass which allows warming to 165K. 17O isotopic substitution studies indicate dissolved molecular oxygen is the source of oxygen in CysSOO.. Anisotropic g-values and the parallel anisotropic 17O hyperfine couplings for this radical are reported.

Cyclic N-Oxides↗
PubMed1988

Effect of chronic haloperidol treatment on peripheral benzodiazepine binding sites in cerebral cortex of rats.

The effects of 21 days of haloperidol treatment on central benzodiazepine (BZ) receptors in the cerebral cortex of rats and on peripheral-type BZ binding sites (PBS) in the cerebral cortex and heart of rats were studied. Neuroleptic treatment did not affect the maximal binding capacity or the affinity of the central BZ receptor to 3H-flunitrazepam. Chronic haloperidol treatment resulted in a significant increase of 38% in PBS density in the cerebral cortex, with no alteration in PBS density in the heart. No alteration in PBS affinity for its ligand 3H-PK 11195 was observed, either in the cerebral cortex or in the heart. The modulatory effect of chronic haloperidol administration on PBS density in the brain may be related to some of the neurobehavioral or hormonal effects of the drug.

Animals↗
PubMed1988

An ESR investigation of the reactions of glutathione, cysteine and penicillamine thiyl radicals: competitive formation of RSO., R., RSSR-., and RSS(.).

The reactions of the cysteine, glutathione and penicillamine thiyl radicals with oxygen and their parent thiols in frozen aqueous solutions have been elucidated through electron spin resonance spectroscopy. The major sulfur radicals observed are: (1) thiyl radicals, RS.; (2) disulfide radical anions. RSSR-.; (3) perthiyl radicals, RSS. and upon introduction of oxygen; (4) sulfinyl radicals, RSO., where R represents the remainder of the cysteine, glutathione or penicillamine moiety. The radical product observed depends on the pH, concentration of thiol, and presence or absence of molecular oxygen. We find that the sulfinyl radical is a ubiquitous intermediate in the free radical chemistry of these important biological compounds, and also show that peroxyl radical attack on thiols may lead to sulfinyl radicals. We elaborate the observed reaction sequences that lead to sulfinyl radicals, and, using 17O isotopic substitution studies, demonstrate that the oxygen atom in sulfinyl radicals originates from dissolved molecular oxygen. In addition, the glutathione thiyl radical is found to abstract hydrogen from the alpha-carbon position on the cysteine residue of glutathione to form a carbon-centered radical.

Chemical Phenomena↗
PubMed1988

Growth and phenotypic characteristics of human nevus cells in culture.

Nevus cells were isolated from the three cutaneous components, epidermis, basal layer, and dermis, of nonmalignant pigmented lesions and were cultured separately in the presence or absence of the phorbol ester 12-0-tetradecanoyl phorbol-13-acetate in medium that supports the rapid proliferation of melanocytic cells. The separation procedure used provided cultures that were essentially free from normal melanocytes (dermis) or fibroblasts (epidermis). In short term culture, nevus cells of all skin compartments expressed markers associated with differentiated melanocytes, such as presence of premelanosomes and melanosomes and elevated tyrosinase levels. Nevus cells also expressed melanoma-associated antigens, such as NGF-receptor, transferrin-related p97, proteoglycan, and HLA-DR as detected with monoclonal antibodies. After several subpassages, cells showed a decreased expression of melanoma-associated antigens, decreased tyrrosinase levels, and melanosomes could no longer be detected. Morphologically, these cells were similar to fibroblasts. The disappearance of melanoma-associated cell surface antigens was concomitant with the appearance of a melanocyte-associated 145 kd protein that might serve as a marker of fibroblast-like differentiation in nevus cells and normal melanocytes. Nevus cell cultures grown in the presence of 12-0-tetradecanoyl phorbol-13-acetate maintained a stable differentiated phenotype throughout their lifespan. As reported earlier, nevus cells in culture, irrespective of the presence or absence of 12-0-tetradecanoyl phorbol-13-acetate, have a finite lifespan in vitro, grow anchorage-independent in soft agar, but do not form tumors when xenografted to nude mice. These studies demonstrate that nevus cells isolated from the epidermal, basal layer, and dermal components of lesional skin can serve as models to characterize the initial steps of tumor progression in a human cell system.

Adolescent↗
PubMed1988

Intraoperative development of contralateral epidural hematoma during evacuation of traumatic extraaxial hematoma.

Intraoperative development of an epidural hematoma contralateral to a craniotomy for acute traumatic extraaxial hematoma has been previously reported. This entity, however, has never been distinctly defined and differentiated from either the delayed or the bilateral acute epidural hematoma. We present 3 new cases of intraoperative contralateral acute epidural hematoma and review the 14 previously reported cases. The typical clinical presentation is a severe head injury with an acute extraaxial hematoma and severe ipsilateral brain displacement during craniotomy. If brain displacement is not noted at craniotomy, then the contralateral hematoma is manifested by immediate postoperative neurological deterioration or intractable elevated intracranial pressure. The presence of any of these signs makes an immediate postoperative CT scan or burr holes contralateral to the original craniotomy mandatory for early diagnosis. In addition to defining "intraoperative contralateral epidural hematoma," stricter definitions of the terms "delayed epidural hematoma" (no hematoma present on the initial CT scan but one present on a later scan) and "bilateral epidural hematomas" (present on the initial scan) are proposed.

Adolescent↗
PubMed1988

[A sparing operation in fracture of the radius head using pinning with resorbable Biofix material].

The incidence of dislocated, subcapitular radial head fracture is discussed. The traditional treatment of this fracture dictates resection of the radial head which induces disturbances of the elbow and wrist. The author has used the bio-degradable material BIOFIX as a 4.5 mm thick pin for internal splinting of the fracture. Early mobilization is possible and later no metal has to be removed. By demonstrating one case of treatment by BIOFIX the author shows a new chance for conservation of the radial head and thereby of the function of the joints.

Adult↗
PubMed1987

Sulfinyl radical formation from the reaction of cysteine and glutathione thiyl radicals with molecular oxygen.

Using Electron Spin Resonance spectroscopy at low temperatures, we find that thiyl radicals resulting from irradiation of frozen aqueous solutions of a variety of thiols, including cysteine, glutathione, and penicillamine react with oxygen to form sulfinyl (RSO.) radicals. The identity of the cysteine sulfinyl radical has been confirmed by the use of molecular oxygen isotopically labeled with 17O. Previous workers have suggested the reaction of thiyl radicals and molecular oxygen resulted in the formation of the potentially damaging thiol peroxyl radical, RSOO.; our work shows no evidence for this species. The sulfinyl radicals are suggested to result from a direct reaction between thiyl radicals and molecular oxygen. This reaction results in the cleavage of the dioxygen bond.

Cysteine↗
PubMed1987

The effect of fibronectin therapy and fibronectin deficiency on healing of rat burns and excision wounds.

Rats with standardized burns and skin excision wounds were treated i.p. with human fibronectin or swine skin gelatin. Controls received bovine albumin, solvent, or no treatment. Wound healing was assessed by planimetry, additionally plasma fibronectin was determined. Solvent or albumin did not influence the healing process, neither did fibronectin. However, when opsonizing fibronectin was additionally consumed by application of gelatin, a significant retardation of wound healing was observed. The results support the opinion that fibronectin is of essential importance for posttraumatic opsonization of gelatin-like material originating from the damaged tissue.

Animals↗