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Biomedical subjects

D Robbins

Publications and source records attributed to D Robbins.

At least 55 records · Page 3Linked to original sources
PubMed1986

Activated terminal complement in cerebrospinal fluid in Guillain-Barré syndrome and multiple sclerosis.

A quantitative enzyme-linked immunosorbent assay was used to measure the concentration of fluid-phase complement C5b-9 complexes (SC5b-9) in the cerebrospinal fluid (CSF) of 14 patients with acute monophasic Guillain-Barré Syndrome (GBS), 21 patients with multiple sclerosis (MS), and 11 patients with noninflammatory central nervous system (CNS) diseases. SC5b-9 complexes were detected in the CSF of 13 of 14 patients with acute GBS (mean, 3.08 micrograms/ml; range, 0 to 7.1 micrograms/ml) and 16 of 21 patients with MS (mean, 1.83 micrograms/ml; range, 0 to 7.5 micrograms/ml). In the control group of patients with noninflammatory CNS diseases, SC5b-9 was not detected in eight of 11 and was present in low concentrations in the remaining three patients (mean, 0.28 micrograms/ml; range, 0 to 1.7 micrograms/ml). The finding of SC5b-9 complexes in the CSF of patients with GBS and MS suggests that terminal complement components may participate in the tissue-damaging processes in these diseases.

Complement Activation↗
PubMed1983

Comparison of ribosomal entry and acceptor transfer ribonucleic acid binding sites on Escherichia coli 70S ribosomes. Fluorescence energy transfer measurements from Phe-tRNAPhe to the 3' end of 16S ribonucleic acid.

Distances were measured by nonradiative energy transfer from fluorescent probes specifically located on one of three points of yeast or Escherichia coli Phe-tRNAPhe enzymatically bound to the entry site or to the acceptor site of E. coli 70S ribosomes to energy-accepting probes on the 3' end of the 16S ribonucleic acid (RNA) of the 30S subunit. The Y base in the anticodon loop of yeast tRNAPhe was replaced by proflavin. Fluorescein isothiocyanate was attached to the X base (position 47) of E. coli tRNAPhe. E. coli tRNAPhe which had been photochemically cross-linked between positions 8 and 13 followed by chemical reduction to form a fluorescent probe was also used. Labeled tRNAs were aminoacylated and enzymatically bound to the ribosome in the presence of elongation factor Tu and guanosine 5'-triphosphate (acceptor-site binding) or a nonhydrolyzable analogue (entry-site binding). Nonradiative energy transfer measurements were made of the distances between fluorophores located on the Phe-tRNA and the fluorophore at the 3' end of 16S RNA. Calculations were based on comparison of the fluorescence lifetime of the energy donor, located on the Phe-tRNA, in the absence and presence of an energy acceptor on the 3' end of the 16S RNA. Under both sets of binding conditions, the distances to the 3' end of 16S RNA were found to be the following: cross-linked tRNA, greater than 69 A; Y base of tRNA, greater than 61 A. The distance between the 3' end of 16S RNA and the X base of tRNA was found to be 81 A under acceptor-site binding conditions but greater than 86 A under entry-site binding conditions.

Energy Transfer↗
PubMed1983

A cluster of adolescent suicide attempts: is suicide contagious?

Adolescent self-destructive behavior has increased during recent decades. Suicide now ranks third as a cause of death among older teenagers. Although recent studies have highlighted multiple risk factors for this behavior, little attention has been paid to the role of contagion as a possible cause for suicide attempts. Within a 6-month period, a small suburban community experienced two adolescent deaths from suicide followed by five attempts and an admission for suicidal ideation, within 7 weeks subsequent to the second fatality. The six patients were among a group of students from the same high school who not only related to each other during the school day but who also visited each other at the time of hospitalization for suicidal behavior. The possible role of suicidal behavior precipitating other self-destructive attempts within a peer group is explored. The development of strategies for dealing with issues of depression and suicide within a high-school environment may be needed.

Adolescent↗
PubMed1982

Hospice criteria.

Explore the source record for details and available documents.

Hospices↗
PubMed1981

Position of transfer ribonucleic acid on Escherichia coli ribosomes. Distance from the 3' end of 16S ribonucleic acid to three points on phenylalanine-accepting transfer ribonucleic acid in the donor site of 70S ribosomes.

Escherichia coli 16S RNA from 30S ribosomal subunits was isolated, oxidized at the 3' end, and labeled with the thiosemicarbazide derivatives of fluorescein or eosin. Labeled 16S RNA was reconstituted into 30S subunits. They were almost fully active compared to 30S subunits reconstituted from unlabeled 16S RNA by using a poly(uridylic acid)-directed polyphenylalanine synthesis assay. Fluorophores were placed at three different positions of tRNAPhe. E. coli and yeast tRNAPhe were oxidized at the 3' end and labeled with the thiosemicarbazide derivative of fluorescein or with the hydrazide of N-methylanthranilic acid. The Y base in the anticodon loop of yeast tRNAPhe was replaced by proflavin or 1-aminoanthracene. Also, E. coli tRNAPhe was photochemically cross-linked between 4-thiouridine at position 8 and cytidine at position 13. After reduction, this site was used as a fluorescent probe. The labeled tRNAs were bound into the peptidyl site of 70S ribosomes, and then the distances from the fluorophore in the modified tRNA to the fluorophore at the 3' end of 16S RNA were measured by nonradiative energy transfer. Calculations were based on measurements of fluorescence lifetimes. The distances to the 3' end of 16S RNA were found to be as follows: 3' end of tRNA, 67-74 A; cross-linked t RNA, 53-60 A; anticodon loop of tRNA, greater than 61 A.

Binding Sites↗
PubMed1979

A correlated thin-section and freeze-fracture analysis of guinea pig adrenocortical cells.

Comparison of the fine structural features of guinea pig adrenocortical cells as seen in thin sections with those revealed by freeze-fracture confirms the structural appearance of steroid-secreting cells as interpreted from thin sections and reveals significant new features of the membranous organelles. Smooth-surfaced endoplasmic reticulum appears as a network of tubules, interwoven or in parallel, and as cisternae, fenestrated and non-fenestrated. These elements are tightly packed in the deeper cortical cells, excluding other organelles from their domain. Tubules and fenestrated cisternae possess randomly distributed intramembranous particles on their PF faces, while closely packed non-fenestrated cisternae possess aggregates of particles interspersed with aparticulate regions on their PF faces. These differences in particle distribution suggest functional specialization among the various forms of reticulum. Mitochondria appear as elongated structures of varying shape. Freeze-fracture reveals that all their cristae have circular origins from the inner membrane. Sinuous tubules, which appear as tubules in section, and straight tubules, which appear as lamellae in section, arise from single sites. Flattened sac-like cristae may have multiple circular origins. Definite contact points seen between inner and outer membranes may facilitate passage of molecules, including steroids, into the mitochondrial compartments. Lysosomes and peroxisomes, which are easily identified in thin sections with the aid of cytochemistry, are difficult to identify with certainty by freeze-fracture. Single membrane-bound granules of slightly smaller diameter than mitochondria may represent lysosomes. Smaller granules interconnected with the tubular reticulum, as well as dilated regions of this organelle, may represent peroxisomes. Plasma membranes show no indication of tight junctions but do have abundant gap junctions which show a zonal differentiation: small gap junctions throughout the cortex, medium-sized regularly shaped gap junctions in zona fasciculata externa, and large irregular gap junctions in zona fasciculata interna and zona reticularis. The large junctions cover planar areas as well as surfaces of projections of one cell into another. Such junctions may allow passage of ions as well as of low-molecular-weight substances between the cells, facilitating or even amplifying the response to trophic hormone stimulation.

Adrenal Cortex↗
PubMed1975

Identification of women at risk for unwanted pregnancy.

Concern about increasing rates of unwanted pregnancy, particularly among adolescents, has led to consideration of steps necessary to develop effective intervention programs. In order to reach a young woman for counseling and contraceptive assistance before she places herself at risk for unintended pregnancy, it seems necessary to develop the capability for identifying high-risk individuals without reference to sexual history. The authors describe a preliminary attempt to predict contraceptively unprotected coitus from responses to projective test stimuli, noting that the problem is so urgent that even early and necessarily incomplete work in this area may have merit in stimulating further research in identification of women at risk for unwanted pregnancy.

Adolescent↗