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Biomedical subjects

D Rosen

Publications and source records attributed to D Rosen.

At least 109 records · Page 6Linked to original sources
PubMed1982

Amino-terminal sequences of the L, M, and H subunits of reaction centers from the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26.

We have determined the sequence of the 25-28 amino-terminal residues of the three subunits, L, M, and H, of the membrane-bound reaction center protein of the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26. The sequences are as follows: L, H2N-Ala-Leu-Leu-Ser-Phe-Glu-Arg-Lys-Tyr-Arg- Val-Pro-Gly-Gly-Thr-Leu-Val-Gly-Gly-Asn-Leu-Phe-Asp-Phe-(His)-Val-; M, H2N-Ala-Glu-Tyr-Gln-Asn-Ile-Phe-Ser-Gln-Val-Gln-Val-Arg-Gly-Pro-Ala-Asp-Leu-Gly-Met-Thr-Glu-Asp-Val-Asn-Leu-Ala-Asn-; H, H2N-Met-Val-Gly-Val-Thr-Ala-Phe-Gly-Asn-Phe-Asp-Leu-Ala-Ser-Leu-Ala-Ile-Tyr-Ser-Phe-Trp-Ile-Phe-Leu-Ala-X-Leu-Ile-. The H sequence, especially after the aspartyl residue at position 11, is rich in hydrophobic residues, consistent with the possibility that this section of the polypeptide chain is located within the membrane. The L sequence is hydrophilic near the amino terminus and then becomes moderately hydrophobic. The M sequence is of average polarity.

Amino Acid Sequence↗
PubMed1982

Spatial relationships of microtubule-organizing centers and the contact area of cytotoxic T lymphocytes and target cells.

Specific binding (conjugation) of cytotoxic T lymphocytes (CTL) to target cells (TC) is the first step in a multistage process ultimately resulting in dissolution of the TC and recycling of the CTL. We examined the position of the microtubule organizing center (MTOC) of immune CTL bound to specific TC. Immunofluorescence labeling of freshly prepared CTL-TC conjugates with tubulin antibodies indicated that the MTOC in essentially all conjugated CTL but not in the conjugated TC were oriented towards the intercellular contact site. This finding was corroborated by electron microscopy examination of CTL-TC conjugates fixed either immediately after conjugation or during the lytic process. Antibody-induced caps of membrane antigens of CTL such as H-2 and Thy 1, did not show a similar relationship to the MTOC. Incubation of CTL-TC conjugates, 10-15 min at room temperature, resulted in an apparent deterioration of the microtubular system of conjugated CTL. It is proposed that the CTL plasma membrane proximal to the MTOC is particularly active in forming stable intercellular contacts, resulting in CTL-TC conjugation, and that subsequent modulation of the microtubular system of the CTL may be related to the cytolytic response and to detachment of the effector cell.

Animals↗
PubMed1980

Interaction of cytochrome c with reaction centers of Rhodopseudomonas sphaeroides R-26: determination of number of binding sites and dissociation constants by equilibrium dialysis.

The number of binding sites and dissociation constants of cytochrome c (horse heart) and cytochrome c2 (Rhodopseudomonas sphaeroides) to reaction centers of Rhodopseudomonas sphaeroides R-26 was determined by equilibrium dialysis. One binding site was found for both cytochromes. The dissociation constants (10 mM Tris-HCl, pH 8.0) were approximately 0.4 microM and approximately 1.0 microM for cytochrome c and cytochrome C2 respectively. Oxidized and reduced forms of both cytochromes bound to reaction centers with approximately equal affinity.

Bacterial Proteins↗
PubMed1980

Automated measurement of peripheral nerve fibres in transverse section.

Transverse sections of rat tibial nerve were scanned with an automated flying-spot microscope and the pictures examined in a one bit (black-and-white) form. Computer programs have been developed, and are described briefly, to isolate individual nerve fibres in the field of view, and to measure axon area and myelin area, from which it is trivial to calculate average axon diameter and average myelin thickness if the axon is assumed to be circular in cross-section. At the magnification used, it was possible to measure 40-50 fibres per field and the time required to do this was 5-7 minutes. For each specimen, 7-8 fields were measured, providing data on 300-400 fibres. Measurements, made on nerves from rats between 3 and 38 weeks of age, show the rate at which nerve fibres grow and also show that the ratio between axon diameter and fibre diameter remains constant, within experimental error, over this period and is close to the predicted value.

Age Factors↗
PubMed1979

Establishment and characterization of a human null-cell lymphoblastic lymphoma cell line (K-LL-3).

A new cell line (K-LL-3) with exceptional characteristics was derived from a bone-marrow aspirate from a patient with poorly differentiated lymphoblastic lymphoma. The cell line was established and the cells maintained on agar feeders for over 1 year. The morphology and cytochemical staining of the primary tumor and the cell line were remarkably similar. The growth characteristics, chromosome pattern, cell-surface receptors and Epstein-Barr pattern, cell-surface receptors and Epstein-Barr virus studies clearly differentiated this cell line from non-malignant lymphoblastoid cell lines. The assay technique used was able to correlate in vitro colony growth with the patient's clinical course. The cells grew on the agar as colonies rather than as a single-cell suspension, and individual colonies could be aspirated and successfully passaged. The K-LL-3 cells lacked cell-surface markers (cytoplasmic and surface immunoglobulins, Fc receptors, C3 receptors, SRBC) except HL-A and thus were classified as null cells. These cells were EBNA (Epstein-Barr virus-specific nuclear antigen) negative and had a pseudodiploid 46XY karyotype.

Adolescent↗
PubMed1979

A reliable method for evaluating drug compliance in children with cancer.

Poor drug compliance may cause a decreased survival of children with malignancies. Children who fail to take their medications are not receiving optimum amounts of chemotherapy and suboptimal therapy causes a shortened survival in children with cancer. This is a study of prednisone compliance in 52 children with cancer during three distinct phases of therapy. The patients were either known to be taking prednisone (on-therapy group), off prednisone (off-therapy group), or their compliance was unknown (unknown group). Evaluation of prednisone compliance was attempted by measuring hemoglobin level changes, weight changes, and random urinary 17-ketogenic steroids. The results obtained show that while hemoglobin and weight changes are not helpful, a random urine 17-ketogenic steroid assay is able to differentiate clearly those patients who are taking their prednisone. By the use of this assay it was found that 33% of patients who by protocol and instruction were supposed to be receiving prednisone were not complying. Separate analysis of adolescents revealed an even more alarming 59% noncompliance rate. This striking level of noncompliance strongly suggests that the survival of patients may be threatened by noncompliance.

17-Ketosteroids↗
PubMed1979

Experimental retinal branch vein occlusion in rhesus monkeys. I. Clinical appearances.

Branch and hemisphere vein occlusion were produced in rhesus monkeys by argon laser photocoagulation. The following observations were made: (1) Immediately after occlusion there was venous dilatation, delayed filling of the artery, delayed drainage by the occluded vein, and capillary leakage. (2) Two patterns of evolution were identified within the first week. In some animals the fundus changes resolved and the retina returned to normal, while in others there was progressive retinal capillary closure. (3) Those animals destined to have capillary closure had diffuse or cluster retinal haemorrhages at 24 hours. (4) Capillary closure took place over 1 week and was usually complete over large areas of retina. (5) Retinal atrophy and major vessel changes occurred over several weeks. (6) Retinal revascularisation occurred in those areas of closure, though this was often limited. It was concluded that the early changes mimicked those seen in human retinal vein occlusion, though persistent retinal oedema and preretinal neovascularisation were not identified.

Animals↗
PubMed1977

The effect of anti-lipolytic agents on isoprenaline-induced myocardial necrosis in the rat.

The effect of inhibiting isoprenaline-induced lipolysis on the degree of damage produced in the rat myocardium by this amine has been investigated by pre-dosing rats with the anti-lipolytic agent 5-fluoro-nicotinic acid. The degree of myocardial necrosis produced in animals given isoprenaline alone and those pre-dosed with the anti-lipolytic agent was measured by the use of an automated flying spot microscope to show absence of formazan from dead muscle fibres in sections treated to demonstrate succinic dehydrogenase. The use of the anti-lipolitic considerably reduced the degree of myocardial damage produced by a standard dose of isoprenaline bitartrate. This was associated with an inhibition of the post-isoprenaline rise in plasma free fatty acid levels. The results are discussed in relation to the possible protective roles of the lowering of plasma free fatty acid levels and inhibition of the adenyl cyclase system at the plasma membrane of the myocardial cell produced directly by the anti-lipolytic.

Animals↗
PubMed1976

Poly(A)-associated RNA from the mitochondrial fraction of the fungus Trichoderma.

Total RNA was extracted from purified mitochondrial and cytoplasmic fractions of germinating conidia of Trichoderma viride and bound to oligo(dT)-cellulose at 22 and 4 degrees C. Under chromatographic conditions which retained very short poly(A) segments (i.e., 4 degrees C), up to 10% of short-term 32PO4-lebeled RNA from the mitochondrial fraction were selectively bound. The poly(A)-associated RNAs from the mitochondrial and cytoplasmic fractions showed the following characteristics. (a) On polyacrylamide gels mitochondrial fraction RNA had a distinctive pattern with a major peak at about 22 S and a smaller one at about 29 S; in contrast, cytoplasmic fraction RNA was heterogenously distributed along the gel. (b) The poly(A) segment released by RNAase digestion of mitochondrial fraction poly(A)-associated RNA migrated on polyacrylamide gels as molecules 20-25-nucleotides long, while that of the cytoplasmic fraction showed an apparent size of 50-60 nucleotides. (c) Mitochondrial fraction RNA bound to oligo(dT)-cellulose in the cold had a guanine + cytosine content of 21% versus 34% for bulk mitochondrial RNA and 48% for cytoplasmic poly(A)-associated RNA; the oligo(dT)-bound RNAs were further identified by their high percentages of adenine residues (46% for the mitochondria and 30% for the cytoplasm). (d) The poly(A)-associated RNA fraction was translated, in vitro, in a cell-free protein-synthesizing system from wheat germ. The products induced by cytoplasmic RNA showed a complex pattern on polyacrylamide gels of many polypeptides ranging in molecular weights from 10000 to 40000. The pattern induced by mitochondrial fraction RNA however, was much simpler, revealing two discrete, main products: a major one at Mr approximately 13000 and a minor one at Mr approximately 20000.

Chromatography, Affinity↗
PubMed1976

A possible new sorbent dialyser for haemodialysis.

A system is proposed for haemodialysis which involves both dialysis and adsorption. The blood compartment is separated by a membrane from a compartment containing adsorbents and ion exchangers under reduced pressure. Urea is broken down by urease adsorbed on an ion exchanger. The ammonia produced is pumped out and the rest of the unwanted substances are bound to the adsorbing materials. The geometry and principles governing the operation of the device obviate the use of circulating dialysate fluid. Preliminary results from in vitro experiments with such a system are reported and the possibility of using this system clinically is discussed.

Adsorption↗
PubMed1975

The effect of fluoride alone or fluoride followed by calcium and vitamin D on disuse osteoporosis of the rat tail vertebrae.

The therapeutic effect of fluoride alone or fluoride followed by calcium and vitamin D administration on the osteoporosis induced by immobilization of the rat tail vertebrae was investigated. Tail immobilization was carried out by musclectomy and tendectomy. After 60 days of immobilization, the vertebrae were examined for bone mass, breaking strength, ash percentage and Ca, P and F content. NaF or Ca and vitamin D as separate treatments improved the osteoporosis induced by immobilization. The effects of NaF treatment were more pronounced than those of Ca and vitamin D. NaF and NaF followed by Ca and vitamin D produced a similar degree of improvement in breaking strength. The fact that fluoride and calcium and vitamin D were administered separately and sequentially may explain the absence of a synergistic effect.

Animals↗
PubMed1975

Vanadium compounds and ferrocyanide as ionic redox agents in photosynthesis.

The effect of such ionic redox agents as ferrocyanide and several vanadium compounds was determined on photosynthetic reactions of spinach chloroplasts. It was found that: 1. Vanadyl sulfate like ferrocyanide in moderately high concentrations (0.03 M) donates electrons to Photosystem II. 2. Decavanadate in the presence of 2,5-dibromothymoquinone accepts electrons in Photosystem II. 3. In the absence of a block between the two photosystems, decavanadate accepts electrons in Photosystem I in the vicinity of plastocyanin or beyond. 4. Vanadite and ferrocyanide in high concentrations (0.32 M) donate electrons to Photosystem I. 5. On the basis of chelator inhibition and polyoxyethylene sorbitan monolaureate treatment, the vanadite oxidation site is located near plastocyanin while the ferrocyanide site is between plastocyanin and P-700.

Chloroplasts↗