Biomedical subjects

R L Sloan

Publications and source records attributed to R L Sloan.

22 records · Page 2Linked to original sources

PubMed1977

Covalent attachment of peptides to cytochrome C for automated sequence determination.

Because small peptides are lost into the organic solvents used, it is virtually impossible to obtain the complete amino acid sequence of a small peptide using only an automated peptide sequencer of the spinning cup type. To overcome this problem we have extended peptides at the carboxy terminus by attachment to equine cytochrome c by a water soluble carbodiimide, relying on the acetylated N-terminus of the cytochrome to minimize its direct contribution to recovery of PTH-amino acids. The Model Peptide H-Leu-Trp-Met-Arg-phe-Ala-OH was used for most experiments. After reaction of 3H-peptide with cytochrome c, about one-third of the tritium counts migrated with cytochrome c during gel filtration. After attachment, the amino acid sequence of the hexapeptide was readily determined with a single cleavage Quadrol program in a Beckman 890B sequencer, whereas only the N-terminal residue was recovered without attachment. The repetitive yield after attachment was 95-96%, with 21-27+ overlap and an initial yield of 18-20%. Sequence data with other peptides illustrate applications and present limitations of our approach.

Amino Acid Sequence↗

PubMedDate not supplied

Palliative therapy of malignant esophageal stricture with the bipolar tumor probe and prosthetic tube.

Patients with malignant esophageal stricture and dysphagia were prospectively randomized to receive palliative therapy with the bipolar tumor probe (17) or prosthetic tube insertion (13). Both treatments gave good relief of dysphagia compared with pretreatment values on a dysphagia score, the results being statistically significant (p less than 0.005). However, there was no difference in the improvement achieved by one method compared with the other. The tumor probe was not difficult to use and complication rates were comparable. In the Atkinson tube group, two patients developed complications related to the position of the prosthesis and in three others food blocked the tube. Treatment with the tumor probe needed repeating at intervals (median, 28 days; range, 2 to 86 days) in all but four individuals to maintain palliation, with each patient needing a median of two treatments (range, 1 to 8). The probe may have advantages in very high esophageal lesions and may facilitate the treatment of tumor overgrowth or undergrowth of a tube. The prosthetic tube may give long-lasting relief of dysphagia and remains the treatment of choice for bronchopulmonary fistulas.

Adenocarcinoma↗

PubMedDate not supplied

Fluoxetine as a treatment for emotional lability after brain injury.

Emotional lability or emotionalism is a relatively common phenomenon and frequently occurs following vascular or traumatic brain injury. It is distressing and embarrassing to sufferers and their families, and often interferes with rehabilitation. At present there is no satisfactory or reliable treatment for this condition. We describe an open trial using fluoxetine, a newer antidepressant with a specific serotonergic action, in the treatment of emotional lability due to brain injury. Six consecutive cases of emotional lability attending a rehabilitation unit were studied (five cases of cerebrovascular accident and one of traumatic brain injury). Response to treatment was measured using a modification of the scale described by Lawson and MacLeod [1]. All showed a marked improvement within one week of commencing fluoxetine and the drug was well tolerated with no reported side-effects. The speed of onset and degree of improvement suggest that fluoxetine may be a useful agent in the treatment of emotional lability due to brain injury. Our observations indicate that further investigation of the role of fluoxetine in the treatment of emotional lability is warranted.

Adult↗

PubMedDate not supplied

Gel filtration chromatographic studies of the isolated membrane domain of band 3.

We have investigated the oligomeric state of the membrane domain of band 3 (MDB3) in non-ionic detergent solution using Sepharose CL-4B gel filtration chromatography to study the hydrodynamic properties of the protein as a function of its concentration. The studies were performed in a C12E9 (polyoxyethylene-9-lauryl ether) buffer containing phosphatidylcholine and sodium chloride, which significantly slow a dilution-induced band 3 conformational change, and an associated aggregation process. Under these conditions native MDB3 eluted predominantly as a single Gaussian peak with a Stokes radius of 76 +/- 14 A, at all protein concentrations studies between 0.2 and 12 microM. This value agrees with the calculated Stokes radius (74 A) determined from the crystal structure of the MDB3 dimer. The Stokes radius of the MDB3 monomer was obtained experimentally by treating native MDB3 with 0.5% SDS, and exchanging the SDS for C12E9 on the Sepharose column. SDS-treated MDB3 showed two peaks whose ratio was strongly dependent on applied protein concentration. The peak representing the largest material had a Stokes radius of 69.7 +/- 14 A, which is essentially the same as the native MDB3 dimer. The peak representing the smaller material had a Stokes radius of 36 +/- 9 A, and was assigned as the MDB3 monomer in C12E9. Evidence is discussed which indicates that the C12E9 monomer specifically self-associates to form a functional MDB3 dimer. We conclude that native MDB3 exists as a stable dimer in mixed micellar solutions composed of C12E9 and phosphatidylcholine, and that the dimer can be dissociated to monomers only by denaturation.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗