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Biomedical subjects

C H Smith

Publications and source records attributed to C H Smith.

At least 109 records · Page 6Linked to original sources
PubMed1992

Cell culture of macular epiretinal membranes.

To attempt to differentiate the cells of origin in epiretinal membranes, cells were cultured from an idiopathic epiretinal membrane and an epiretinal membrane that formed after successful repair of a retinal detachment. The cells exhibited a variety of forms. When the cells from the idiopathic epiretinal membrane were incubated with melanin from donor eyes a population of small cells accumulated the pigment, but the large, flat cells did not. The epiretinal membrane was not composed of a single cell type. Although a population of cells exists within epiretinal membranes, no one cell type could be identified as the cell type of origin.

Aged↗
PubMed1991

Asymptomatic orbital cavernous hemangiomas.

Computed tomographic (CT) scanning and magnetic resonance imaging (MRI) are commonly performed to evaluate neurologic symptoms. Rarely are asymptomatic orbital tumors discovered, creating uncertainty about their management. Eleven patients are presented who were referred for asymptomatic orbital tumors discovered on either CT scanning or MRI performed for unrelated symptoms of headache, vertigo, peripheral numbness, seizures, stroke, or hallucinations. The asymptomatic orbital tumors were diagnosed clinically and radiologically as cavernous hemangiomas. All the patients were followed clinically and neuroradiologically for an average of 37 months (range, 8 to 120 months). None of the tumors enlarged during this time. The authors conclude that patients who have asymptomatic cavernous hemangiomas, discovered by coincidence during neuroimaging, that bear no relation to the indication for obtaining the CT scan or MRI, can be safely followed by observation as an alternative to surgical excision.

Adult↗
PubMed1991

Two cationic amino acid transport systems in human placental basal plasma membranes.

Transport of cationic amino acids in basal (fetal facing) plasma membranes was investigated by characterization of L-[3H]lysine and L-[3H]arginine uptake in membrane vesicles isolated from term human placentas. At least two Na(+)-independent systems were present. Lysine concentration dependence data were fit by a two-system model with Km values of 1.0 +/- 0.8 and 223 +/- 57 microM and Vmax values of 0.06 +/- 0.03 and 24.0 +/- 5.8 pmol.mg protein-1.min-1. In the presence of either 10 mM L-leucine or Na+ plus 10 mM L-homoserine, the data were fit by single system models with kinetic parameters similar to the higher and lower Km systems seen in the absence of inhibitors. Uptake of 10 or 20 microM L-lysine in the absence of Na+ showed the higher Km system was inhibited completely by L-arginine, L-homoarginine, and L-histidine. In the presence of Na+, the higher Km system was inhibited completely by L-alanine, L-homoserine, L-leucine, L-phenylalanine, and L-norleucine. The lower Km system was inhibited completely by L-arginine, L-homoarginine, L-histidine, L-leucine, and L-methionine. Time course studies of uptake demonstrated that uptake by either system alone filled the total vesicular space. The basal membrane of human placental syncytiotrophoblast possesses two transport systems for lysine and arginine, resembling the ubiquitous y+ system and the bo,+ system previously described in mouse blastocysts. The higher Vmax of the y+ system suggests that in utero it may mediate transfer of cationic amino acids from the syncytiotrophoblast to the fetus. The role of the high-affinity low-capacity bo,+ system remains to be determined.

Amino Acids↗
PubMed1991

Pentose phosphate pathway in cellular trophoblasts from full-term human placentas.

Glucose metabolism was investigated in cellular trophoblasts isolated from full-term human placentas. The specific yields of 14CO2 from D-[1-14C]glucose and D-[6-14C]glucose were used to determine glucose metabolism via the pentose cycle for cells freshly isolated or cells grown in culture for 1 and 3 days. Cells were mononucleated on day 1 but fused to form multinucleated syncytiotrophoblasts by day 3. The principal product of glucose metabolism under all conditions was lactate, accounting for approximately three-fourths of recovered 14C in products. Pentose cycle activity contributed 0.57 +/- 0.01, 0.39 +/- 0.06, and 0.21 +/- 0.05% of the glucose metabolized by cells freshly isolated, cultured for 1 day, and cultured for 3 days, respectively. In the presence of the electron acceptor methylene blue, pentose cycle activity increased to 16.5 +/- 2.1, 13.8 +/- 1.5, and 18.2 +/- 1.7% for cells freshly isolated, cultured for 1 day, and cultured for 3 days, respectively. Trace amounts of 14C were recovered in other products including amino acids and glycogen. These data suggest that pentose cycle activity in cellular trophoblasts from full-term placenta, like those in full-term villous tissue, is a minor component of glucose metabolism. However, these cultured cells maintain a capacity to oxidize glucose via the pentose cycle at relatively high rates.

Carbon Radioisotopes↗
PubMed1991

Adrienne Rich, Ruth Whitman, and their Jewish elders.

Adrienne Rich's portraits of her paternal, Jewish elders confirm the view that elders who suppress their ties to Judaism suffer psychologically as they age; however, Rich's depiction of her Jewish mother-in-law shows that elders who maintain their ties can also suffer depression in later stages. In contrast, Ruth Whitman shows that her Jewish grandmothers maintained ties and were content in old age; at the same time, her paternal Jewish grandfather aged peacefully even though he rebelled against Judaism. The portraits drawn by these poets come from a breadth of thinking that tolerates ambiguities, goes beyond generalities to individual differences, and permits sympathy in the midst of criticism.

Adaptation, Psychological↗
PubMed1990

The calcium-transporting ATPase and the calcium- or magnesium-dependent nucleotide phosphatase activities of human placental trophoblast basal plasma membrane are separate enzyme activities.

The properties of calcium-stimulated ATP hydrolysis often differ from those of ATP-dependent calcium transport. We have characterized two components of calcium-stimulated ATP hydrolysis in human placental basal plasma membrane. In the absence of magnesium, component 1 apparently has saturable sites for free calcium in both the nanomolar and low micromolar range. It was stimulated by either calcium or magnesium, was unselective for nucleotide substrate, and its activity was very much greater than that of ATP-dependent calcium transport. Component 1 was inhibited by GTP, permitting measurement of component 2 with activity and magnesium stimulation comparable to ATP-dependent calcium transport. Component 2 was inhibited partially by an antibody against purified erythrocyte calcium transporter and completely by sulfhydryl reagents, whereas component 1 was unaffected. A phosphorylated intermediate of the calcium transporter co-migrated with the erythrocyte transporter on acidic sodium dodecyl sulfate-polyacrylamide electrophoresis gels. Immunostaining after transfer to nitrocellulose revealed a doublet. The band of lower molecular weight co-migrated with that of the human erythrocyte membrane transporter. The addition of GTP permits separate measurement of ATP hydrolysis by the calcium transporter of the placental basal plasma membrane and may be useful in defining its properties in other cell membranes under a variety of conditions.

Adenosine Triphosphatases↗
PubMed1990

Anionic amino acid transport systems in isolated basal plasma membrane of human placenta.

The placenta absorbs anionic amino acids from the maternal and fetal circulations but does not significantly transfer these amino acids from mother to fetus. Uptake of L-aspartate and L-glutamate by basal (fetal-facing) plasma membrane vesicles from placental syncytiotrophoblast was stimulated by an inward sodium and an outward potassium gradient. Measurable saturable uptake was entirely sodium dependent and electrogenic. Studies of concentration dependence resolved a high-affinity (microM) system that has characteristics of the X-AG system found in other tissues including the placental microvillous plasma membrane. Uptake of 0.2 microM L-glutamate was inhibited by 2 mM L-glutamate, L-aspartate, D-aspartate, L-cysteate, and L-cysteinesulfinic acid and was uninhibited by 2 mM D-glutamate, L-glutamine, L-alanine, L-serine, L-asparagine, and taurine or by 1 mM methylaminoisobutyric acid. The X-AG system in the two membranes of the placental syncytiotrophoblast may mediate the concentrative uptake of anionic amino acids from the maternal and fetal circulations into the placenta.

Amino Acids↗
PubMed1990

In pursuit of the moment.

When one paper is a sequel to a previous one, it is altogether too simple to bore the reader with redundancies. It is also quite too easy to lose track of time and jump from one paper to the next and this almost certainly will happen in the present one. Portions of the earlier writing are initially presented and one would hope that these present a valid reason to continue pursuit of "The Moment." After some discussion, it is felt that various previously unmentioned facets of "The Moment" are discussed and perhaps clarified. But it is not defined. It may defy definition and we could hope that this might intensify our pursuit, since physicians are a stubborn group.

Physician-Patient Relations↗
PubMed1989

Comparison of criteria derived by government and patients for evaluating general practitioner services.

A study was carried out to see whether patients' criteria of good health care in general practice were different from those of the government and doctors. A total of 711 patients in a semirural group practice evaluated the importance of 20 criteria describing different facets of care. Half the criteria were derived from Promoting Better Health (health education, easy to change doctors, all children vaccinated, health checks for adults and children under 5, regular screening for cancer, woman doctor available, doctor goes on courses, well decorated premises, convenient surgery times); the other 10 were taken from a preliminary interview study of 24 patients (staff friendly and know me, doctor listens and sorts out problems, same doctor for consultations, nurse on premises, appointments available within 48 hours, waiting time less than 20 minutes, small surgery premises, tests available at surgery). Questionnaires containing 10 pairs of criteria assigned by computer were drawn up and patients asked to give their preference in each pair. The number of times each criterion was preferred was scored and its comparative importance ranked. The three criteria most highly ranked by all patients were having a doctor who listens, having a doctor who sorts out problems, and usually seeing the same doctor (all criteria originated by patients). The three least highly valued were health education, being able to change doctor easily, and well decorated and convenient premises (all criteria originated by the government). The criteria originated by patients as a group scored significantly more highly than those originated by government as a group. In a more competitive general practice environment, in which doctors will be more inclined to satisfy the wishes of patients, officially supported indicators of good quality care might not get the encouragement that the government and doctors think that they deserve.

Adult↗
PubMed1989

Acute pregnancy-associated hypertension treated with hypnosis: a case report.

A 24-year-old patient was treated using hypnotic intervention for acute pregnancy-associated hypertension. The patient displayed evidence of secondary arrest of labor and acute onset of signs and symptoms of pre-eclampsia. Hypnotic intervention resulted in normal vaginal delivery without complications or further evidence of morbidity secondary to a hypertensive episode. Hypnosis as an adjunct in the treatment of pre-eclampsia should be investigated further.

Adult↗
PubMed1989

Alanine transport systems in isolated basal plasma membrane of human placenta.

Concentrative transfer of amino acids from mother to fetus is affected by transport across both microvillous (maternal-facing) and basal (fetal-facing) plasma membranes of the human placental syncytiotrophoblast. Isolated basal plasma membrane vesicles were used to elucidate transport systems for neutral amino acids across this membrane. The concentration dependence and inhibition of zero-trans-alanine uptake were studied and four pathways for alanine uptake were defined as follows: 1) a sodium-dependent system shared by methylaminoisobutyric acid, which has the characteristics of an A system; 2) a sodium-dependent system resistant to inhibition by methylaminoisobutyric acid, which has the characteristics of an ASC system; 3) a sodium-independent system which may resemble an L system; 4) nonsaturable uptake. The microvillous membrane of the syncytiotrophoblast possesses systems similar to 1 and 3, but system 2 is unique to the basal plasma membrane. Active and passive transport of amino acids across both microvillous and basal plasma membranes may contribute to trophoblast amino acid uptake and nutrition and to the transfer of amino acids to the fetus.

Alanine↗
PubMed1989

Calcium pump epitopes in placental trophoblast basal plasma membranes.

The syncytiotrophoblast represents the primary cellular barrier between maternal and fetal circulations in the placenta. Large amounts of Ca2+ are transported across this barrier by mechanisms that are not clearly understood. To further understand this phenomenon, we examined rat and human placenta by immunohistochemical and protein blotting techniques with a monoclonal antibody raised against the human erythrocyte plasma membrane Ca2+ pump. Immunohistochemistry with this antibody showed specific staining in the human placenta of the basal (fetal facing) surface of the syncytiotrophoblast. In the rat placenta, immunohistochemistry also showed specific staining of the innermost (fetal facing) layer of the trophoblast and the basal surface of the endoderm of the intraplacental yolk sac. In Western blots of placental homogenates and membranes, the monoclonal antibody bound to a 140,000-mol wt band, characteristic of Ca2+ pumps in other tissues. Western blots of isolated basal membranes showed more intense staining than isolated microvillous membranes, confirming the results of the immunohistochemistry. In addition, Ca2+ transport in basal membrane vesicles from human placenta was inhibited by polyclonal antibodies prepared against the erythrocyte Ca2+ pump. We conclude that basal (fetal facing) layers of human and rat placentas contain a high-affinity Ca2+ pump situated to transport Ca2+ from the maternal to the fetal circulation.

Animals↗
PubMed1989

Anionic amino acid uptake by microvillous membrane vesicles from human placenta.

The transport mechanisms for anionic amino acids in trophoblast microvillous (maternal facing) membrane were investigated by characterization of L-[3H]aspartate and L-[3H]glutamate uptake in membrane vesicles. Uptake of the anionic amino acids was by a single high-affinity Na+-dependent K+-stimulated cotransporter that is pH sensitive and electrogenic. A second Na+-dependent transporter could not be discriminated, and there was no observable Na+-independent uptake. An outwardly directed K+ gradient (100 mM KCl inside) resulted in a 5- to 10-fold stimulation in glutamate uptake in the presence of Na+. Intravesicular KCl had no effect on transporter affinity but increased transporter velocity in a concentration-dependent manner. Inhibition of Na+-K+-dependent uptake of L-aspartate and L-glutamate (20 mM, 30 s) by 2 mM unlabeled amino acids demonstrated stereoselectivity for L-glutamate but not for L-aspartate. The neutral amino acids (L-alanine, L-threonine, L-serine, L-cysteine, L-phenylalanine) were not effective inhibitors. These data are consistent with an anionic amino acid transporter in the microvillous membrane of the trophoblast, which has characteristics qualitatively similar to the X-AG system found in other epithelia. This system may mediate the concentrative placental uptake of anionic amino acids from maternal blood in utero.

Amino Acids↗
PubMed1989

Hallucinations, delusions and things that go bump in the night.

With considerable overlapping and no little back tracking, the writer has attempted to discuss the psychotic, the neurotic and the victim of Post Traumatic Stress Disorder. Tolerance of overlapping is asked of the reader since it exists and defies our wish that these three miseries could be seen as separate entities. Yet they are sufficiently separate as to demand differing therapeutic approaches so it is necessary to give abbreviated attention to therapies. Attention is given to medical therapies while they are labeled secondary to psychotherapy. It is not mentioned but should be, that occasional exceptions seem to exist. The title and conclusion, first read in adolescence, seems to suggest that emotional disorders have been with us for quite a long while.

Adult↗