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Biomedical subjects

D Worcester

Publications and source records attributed to D Worcester.

7 recordsLinked to original sources
PubMed1984

Primary vertebral tumor in an adolescent girl.

A 13-year-old girl presented with a 6-month history of back pain, a palpable paravertebral mass, and a left third lumbar radiculopathy. Radiologic studies were consistent with a primary vertebral neoplasm. Posterior biopsy yielded material consistent with osteoblastoma. Anterior tumor excision and vertebral reconstruction followed. Elements consistent with aneurysural bone cyst were present in the resected tumor.

Adolescent↗
PubMed1982

Solution scattering studies of dimeric and tetrameric spectrin.

The structure of spectrin dimers and tetramers in solution has been examined by light, low-angle X-ray and neutron scattering. The results show a good correspondence between the solution dimensions of these molecules and their appearance in the electron microscope after shadowing. The scattering profiles are not compatible with an extended rod-like character, but reflect the presence of a considerable degree of bending. The radii of gyration of the dimer and tetramer were determined to be 170 and 375 A and the cross-section radii of gyration 14 and 12.3 A, respectively. Both are thus long, thin, rather bent molecules, and the tetramer is twice the length of the dimer.

Humans↗
PubMed1981

Neutron small angle scattering on selectively deuterated human plasma low density lipoproteins. The location of polar phospholipid headgroups.

Human plasma low density lipoproteins (LDL) were deuterated in the phospholipid headgroup region by exchange with phosphatidylcholine-N(CD3)3-apolipoprotein A complexes. The exchange was associated with a net transfer of phosphatidylcholine to LDL leading to an increase in total phospholipid content by 27%. Practically all of the endogenous phosphatidylcholine including lysophosphatidylcholine, and about one-third of the sphingomyelin pool was found to be exchangeable. Immunochemically, deuterated LDL was identical with native LDL. The hydrodynamic and ultrastructural properties were closely similar for the two particle species apart from a slight increase in overall particle size by about 2%. Both native and deuterated LDL were investigated by neutron small angle scattering at several representative contrasts in H2O/D2O buffers. Subtraction of the scattering amplitudes of native from deuterated LDL resulted in a radius of gyration of 103 +/- 5 A for the N(CD3)3 groups, and in a structure factor resembling that of a thin, spherical shell. Evaluation of the contrast variation experiments in combination with previous data from x-ray small angle scattering (Laggner, P., and Mueller, K. (1978) Q. Rev. Biophys. 11, 371-425) indicates that the phospholipids form a spherical monolayer shell in the radial range between 75 A and 103 A around the core of cholesteryl esters and triglycerides. For the protein moiety, a radius of gyration of 110 A was calculated, indicating that it is located, on average, 5 to 10 A from the polar phospholipid headgroups toward the aqueous environment.

Cholesterol↗
PubMed1976

Neutron diffraction studies of retinal rod outer segment membranes.

Neutron diffraction measurements on isolated retinal rod outer segments show that most of the visual pigment protein, rhodopsin, is embedded in the hydrophobic core of the disk membrane. A very slight outward shift of protein at the cytoplasmic side of the membrane is associated with pigment bleaching.

Animals↗