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Biomedical subjects

R L Potter

Publications and source records attributed to R L Potter.

35 records · Page 2Linked to original sources
PubMed1984

Transition from residency training to academia.

Anxious and depressive reactions during transitions from psychiatry residency to career settings have been reported. The authors describe difficulties encountered in their transition from psychiatry residency to academic psychiatry within the same program. Four stages of transition are described: Termination--a time of separation and grief over losses; Adjustment--a time of ambivalence and uncertainty; Identity Formation--a time of increased productivity and comfort; Consolidation--a time of accomplishment and compatibility of life goals. Women may additionally encounter gender-specific problems in entering a predominantly male profession. The development of supportive relationships within and outside work settings are viewed as the best methods of coping with transitional stress.

Adaptation, Psychological↗
PubMed1983

Regional cell count and respiration in the brain of Rana catesbeiana.

Cell counts were made in three divisions of the bullfrog brain: (1) olfactory lobestelencephalon, (2) diencephalon-mesencephalon, and (3) the hindbrain; average cellular respiration in potassium-enriched Ringer solution and the rate of respiration in sodium-free medium were tested for their possible relationship to the numbers of glia and numbers of neurons in each region. After restoring some of the sodium ions to sodium-free minces, the percent increase in respiration was plotted for each brain segment and compared to the percent of glia per brain division to determine the glial respiratory contribution. Where glial numbers were greater, the potassium-stimulated respiration was greater; where neuronal numbers were greater, the sodium-free respiration was most prominent. The respiration increased most above the sodium-free rate, when sodium ions were added or when the full amount of sodium was present, in the hindbrain, where the glia appear to metabolize more vigorously and the neurons least actively.

Animals↗
PubMed1983

Changes in nucleotide-binding proteins during oocyte maturation in Xenopus laevis.

Photoaffinity nucleotide analogs of ATP and GTP have been used to investigate the purine nucleotide-binding proteins of Xenopus laevis oocytes. These analogs label Xenopus oocyte supernatant proteins in a highly specific manner. The pattern of proteins labeled with these analogs was determined by polyacrylamide gel electrophoresis. A number of changes in this pattern were observed during the time course of progesterone-stimulated maturation in vitro. If one alters the dynamic balance of phosphatase and kinase activities with NaF, these changes are not observed. This photoaffinity approach also provides an assay for the purification of high-affinity nucleotide-binding proteins, including protein kinases, which may be important in the process of oocyte maturation.

Adenosine Triphosphate↗
PubMed1983

Manic-depressive variant syndrome of childhood. Diagnostic and therapeutic considerations.

A case is described of manic-depressive variant syndrome of childhood in a ten-year-old boy. Children with manic-depressive variant syndrome frequently have signs and symptoms of hyperactivity and are often first seen by their pediatrician. The diagnoses of attention deficit disorder, organic mental disorder, borderline personality disorder, and childhood schizophrenia, are discussed with relation to their differentiation from the manic-depressive variant syndrome of childhood. The discussion further describes the early onset of symptoms in this boy and points out how a consideration of this diagnosis might be possible in early childhood, allowing for early inauguration of lithium therapy.

Attention Deficit Disorder with Hyperactivity↗
PubMed1980

The structural domains of cAMP-dependent protein kinase I. Characterization of two sites of proteolytic cleavage and homologies to cAMP-dependent protein kinase II.

The regulatory subunit of cAMP-dependent protein kinase I has been cleaved proteolytically into two structurally independent domains. The larger domain (35K with trypsin or thermolysin and 31K with chymotrypsin) corresponded to the COOH-terminal end of the polypeptide chain and retained the cAMP binding site(s). The smaller domain (11 to 12K with trypsin), corresponding to the NH2-terminal region of the regulatory subunit, contained the region of dimer interaction. In the absence of reducing reagent, the two protomers of the native regulatory subunit and of the smaller domain could be covalently cross-linked by a disulfide bond. In addition to the two major domains, a 15-residue peptide that links the two domains has been isolated and partially characterized. Two major sites on the type I regulatory subunit were susceptible to proteolytic degradation. Site 1, susceptible to cleavage by both trypsin and thermolysin, has the following sequence: LysArg-Arg-Gly-Ala-Ile-Ser-Ala-. Cleavage at this site generated a 35K cAMP-binding fragment. Site 2 contained a chymotryptic cleavage site as well as a secondary tryptic site. The sequence at Site 2 was Val-Arg-Arg-Val-Ile-Ala. Cleavage here generated a 31K cAMP-binding fragment. Both sites contained 2 consecutive basic amino acid residues similar to the corresponding sequence in the type II regulatory subunit; however, in the case of the type I regulatory subunit, the serine at Site 1 does not serve as a site of autophosphorylation. In contrast to the dissociated regulatory subunit, the holoenzyme is partially protected from proteolytic degradation.

Amino Acid Sequence↗
PubMed1977

Regional differences of respiration in the bullfrog brain based on cell density.

The comparison of analogous and homologous regions of the anuran and mammalian brains, according to their rate of oxygen uptake per unit weight of DNA, has revealed a lack of correspondence between the respective brain regions. This discrepancy between corresponding regions was observed during incubation either in low-potassium or in high-potassium Ringer. Per unit weight of DNA, the rate of cellular respiration in the amphibian hindbrain exceeded that of the thalamus-midbrain, and cells in the latter region exceeded those in the telencephalon. Hindbrain values were only higher if based on unit weight of DNA, and were actually lower on a wet weight basis. This pattern contrasted with a uniform rate of oxygen consumption for the homologous regions of the mammalian brain. Such inequalities between the regional brain metabolism of two different classes of vertebrates clearly illustrate the unique evolutionary history of both forms. The intensity of potassium-stimulated oxygen uptake in the three brain regions of the amphibian was interpreted as probably being proportional to the number of glial cells in each area. The smallest percentage of stimulation in the hindbrain may signify fewer glia, and the highest percentage of stimulation in the mid- and forebrain may indicate more numerous glia. Histological descriptions of ependymal glia in consecutive regions of the anuran brain appear to confirm this distribution of non-neuronal cells.

Animals↗
PubMedDate not supplied

Metabolic fate of [U-14C]-labeled glutamate in primary cultures of mouse astrocytes as a function of development.

The metabolic fate of [U-14C]-labeled glutamate in astrocytes grown in primary cultures for 1-3 weeks in the absence or presence of dibutyryl cyclic AMP was followed using dansylation with 3H-dansyl chloride and subsequent thin layer chromatography of the dansylated amino acids. No indication was found of classical metabolic compartmentation, i.e., the specific radioactivity of glutamine (14C/3H ratio) never exceeded that of its precursor, glutamate. In accordance with a relatively late maturation of glutamine synthetase activity the rate of formation of labeled glutamine was much faster in 3-week-old than in 1-week-old cultures. The opposite was found for aspartate formation, but under all conditions incorporation of radioactivity into aspartate was pronounced.

Animals↗