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Biomedical subjects

R J Barrnett

Publications and source records attributed to R J Barrnett.

15 recordsLinked to original sources
PubMed1991

A review of child psychotherapy research since 1963.

Reports on individual nonbehavioral child and adolescent psychotherapy since 1963 are reviewed. Inclusion criteria required some minimal contrasting group. Forty-three studies were assessed for basic methodological adequacy and main findings. The authors conclude that summary impressions from this body of literature cannot be made due to the magnitude of the flaws in basic psychotherapy research methodology. Suggestions are made regarding the future of child and adolescent psychotherapy research.

Adolescent↗
PubMed1990

Psychopathology and developmental delay in homeless children: a pilot study.

The authors report a survey of 50 parent-child pairs from homeless families housed in New York City hotels. The purpose of the survey was to determine the extent of emotional or behavioral disturbances and of developmental delays in homeless children aged 4 through 10 years, the presence of depression or a history of depression or other psychiatric problems in the parents of these children, and to determine whether the children and adults had mental health needs. The results indicate that nearly all of the children showed some difficulties. Sixty-one percent of the children had receptive verbal functioning at or below the first percentile for age, 29% were functioning at the fifth percentile for age in psychomotor ability, and 38% exhibited emotional and behavioral problems. Twenty-eight percent of the parents exhibited evidence of mild to severe depression; a smaller percentage admitted to past psychiatric problems.

Adult↗
PubMed1979

Enucleation of differentiated murine erythroleukemia cells in culture.

Friend murine leukemia cells induced to undergo erythrocytic differentiation by dimethyl sulfoxide give rise to progeny resembling ortho- or polychromatic normoblasts, which usually do not complete the maturation process to yield forms analogous to erythrocytes. Treatment of these differentiated cells with cytochalasin B can lead to a high proportion (i.e., 80-85%) of enucleated cells in vitro. Nuclear extrusion in cells induced to differentiate by dimethyl sulfoxide and subsequently treated with cytochalasin B began within 24-36 hr of exposure to the antibiotic, with the appearance of a pre-enucleated stage in which the cell nucleus became pycnotic and eccentrically located. Maximum enucleation occurred after 72-96 hr of exposure to cytochalasin B and was significantly enhanced when dimethyl sulfoxide was included in the culture medium during the period of treatment with cytochalasin B. Enucleation appeared to take place only in differentiated progeny, because nondifferentiated cells treated with cytochalasin B alone yielded a population of multinucleated cells. The findings indicate that highly tumorigenic nondifferentiated Friend erythroleukemia cells can be converted in high yield to mature enucleated forms that are unable to proliferate in vitro.

Animals↗
PubMed1979

A chemical mechanism for tissue staining by osmium tetroxide-ferrocyanide mixtures.

The presence of Fe(CN)6(-4) provides sequential, one-electron reduction pathways for OSO4. An equilibrium is established containing OSO4, Fe(CN)6(-4), Fe(CN)6(-3), OSO2(OH)4(-4), and labile cyano-bridged OS-Fe species containing Os in nominal oxidation states of VIII, VII, and VI. These osmium complexes are chelated by appropriately placed donor atoms in the macromolecular tissue matrix, and chelation facilitates the reduction of osmium in situ to lower oxidation states (predominantly IV) that are relatively nonlabile. The greater reactivity and concentration of the Os(VII and VI) intermediates in this system leads to more Os deposition than OsO4 alone; the chelation is responsible for the immobilization of Os and the observed staining pattern in electron micrographs. Chemical data from model systems and electron micrographs of tissue are presented in support of this mechanism.

Animals↗
PubMed1978

Biochemical and morphometric studies of the relationship of acetylcholine synthesis and vesicle numbers after stimulation of frog neuromuscular junctions: the effect of a choline-O-acetyltransferase inhibitor.

The present study compares choline acetylase (ChAc) activity with morphometric determinations of synaptic vesicles at the neuromuscular junctions of frog pectoralis muscle subjected to high and low frequency stimulation in the presence or absence of NVP, a ChAc inhibitor. Muscles stimulated at 10/sec for 20 min with one hour rest, in the presence of NVP, showed an approximately 50% reduction in synthesis of Ach, and a 50--60% reduction in the numerical density of synaptic vesicles relative to controls preparations. Similar nerve muscle preparations stimulated at 2/sec for one hour without rest, in the presence of NVP, also showed approximately 50% less synthesis of Ach and vesicle numbers 43% lower than that seen in control muscles treated in the same way in the absence of drug. The results indicate a correlation between the inhibitory effect of NVP on ChAc and the numbers of vesicles present within terminals. In addition, stimulation of nerve terminals, with or without NVP, produced a significant increase in the numerical density of synaptic vesicles over respective unstimulated controls. These and other results are discussed in relation to current hypotheses concerning recirculation of synaptic vesicles.

Acetylcholine↗
PubMed1978

Cytochemical demonstration of sodium, potassium-adenosine triphosphatase by a hemepeptide derivative of ouabain.

A cytochemical probe for the ultrastructural localization of the NaKATPase was devised, which utilizes the biological affinity of the noncompetitive inhibitor, ouabain (ouab) to which was coupled a hemepeptide (H11P) which possesses peroxidatic activity. The conjugate, ouab-H11P, had an apparent Ki of approximately 8 x 10(-7) M. When reacted with fixed tissue from the salt gland of osmotically stressed ducklings, the NaKATPase was localized to the basal and lateral infoldings of the plasma membranes of secretory epithelial cells. Reaction product consisted of fine textured deposits distributed in focal patches on the outer aspects of the membrane. Apical membranes were negative, as were intracellular membrane components. Preincubation of tissue with unlabeled ouabain or binding of ouab-H11P in the presence of 10 mM K+, no ATP and no Mg++, resulted in the absence or diminution of reaction product.

Animals↗
PubMed1978

Ouabain binding during plasma membrane biogenesis in duck salt gland.

The conditions necessary for optimal ouabain binding in the avian salt gland were examined. Binding was enhanced by ATP and Mg2+ and was decreased by K+, but was unaffected by added Na+. Both maximal binding and complete inhibition of Na, K-ATPase activity were obtained at 1 X 10(-6) M ouabain. Half maximal binding and half maximal inhibition of Na, K-ATPase activity were obtained at 1.7 X 10(-7) M ouabain. Ouabain binding increased in parallel with increasing specific activity of the Na, K-ATPase duringsalt-induced salt gland specialization. The ratio of Na, K-ATPase activity to ouabain-binding sites remained constant during the salt stress as well as after removal of the salt diet. Autoradiography indicated binding to partially and fully differentiated secretory cells of the salt gland. The ouabain binding assay appeared to be a more useful indicator of membrane amplification than Na, K-ATPase activity since it is rapid, essentially irreversible, less sensitive to tissue fixatives, and quantitatively measured the number of enzyme molecules.

Adenosine Triphosphatases↗
PubMed1976

The chemical nature of osmium tetroxide fixation and staining of membranes by x-ray photoelectron spectroscopy.

X-ray photoelectron spectroscopy was used to determine the oxidation states of osmium compounds present in erythrocyte ghost preparations and related systems treated with osmium tetroxide. Osmium tetroxide and cholesterol, codeposited at -100 degrees C, began to react at -70 degrees C, and Os(VI) was formed. Similarly, Os(VI) was detected for the known cholesterol-osmate ester prepared and purified chemically. However, osmium tetroxide applied in phosphate buffer (pH 7.2) gave rise to large proportions of Os(IV) and Os(III) species in addition to Os(VI) compounds. Egg phosphatidylcholine likewise produced a mixture of Os(VI), Os(IV), and Os(III), but dipalmitoyl phosphatidylcholine failed to give significant amounts of osmium containing products under identical conditions. Glutaraldehyde gave a mixture of compounds with the same osmium oxidation states when allowed to react with aqueous osmium tetroxide. Unfixed and glutaraldehyde-fixed erythrocyte ghosts also produced mixtures of Ss(VI), Os(IV) and Os(III) under conditions identical to those of normal tissue processing. Additionally, the mixture of adducts initially formed by treatment with osmium tetroxide was further reduced by dehydration of the tissue with ethanol, rpesulting in a final mixture which was 50-60% Os(III). The results support a scheme for the reaction os osmium tetroxide with tissues in which the initial reaction site is the double bonds of unsaturated lipids to form Os(VI) derivatives. Subsequent hydrolysis and further reduction yield complexes of Os(IV) and Os(III). A mixture of these three states is present in membrane specimens during microscopic observation. Os(VI) and Os(IV) could be present as osmate esters and osmium dioxide, respectively; Os(III) could be present as an oxo- or amino complex(es). The photoelectron spectrum of intact erythrocyte ghosts can be synthesized from the spectra of phospholipid and cholesterol only, suggesting the predominance of the reaction with lipids in the fixation process.

Animals↗
PubMed1975

The ultra-structural localization of enzyme activity in unfixed sections.

A technique is described for using conventional unfixed cryostat sections for localising enzyme activities in the electron microscope. The sections are incubated on the slide in the presence of a stabiliser, and then only fixed and embedded after the reaction is complete. Thin sections can then be cut of the reacted section, for electron microscopy. The present article shows that good ultra-structural morphology is retained during the freezing and cutting stages, and although some loss of detail occurs after the incubation, sub-cellular membranes are still intact, and membrane-associated reaction product can be clearly seen.

Animals↗