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Biomedical subjects

C Johnston

Publications and source records attributed to C Johnston.

At least 271 records · Page 15Linked to original sources
PubMed1983

Effects of gold compounds on the function of phagocytic cells. II. Inhibition of superoxide radical generation by tripeptide-activated polymorphonuclear leukocytes.

The effect of sodium aurothiomalate and triethylphosphine gold on the generation of superoxide radicals by chemotactic tripeptide-activated polymorphonuclear leukocytes has been investigated using a cytochrome C reduction technique. Neither gold compound inhibited the binding of the tripeptide to cells. Sodium aurothiomalate in concentrations ranging from 1 to 100 micrograms/ml produced mild, nonsignificant inhibition of the generation of superoxide radicals. In contrast, triethylphosphine gold at a concentration of 0.25 microgram/ml was associated with a mild enhancement of superoxide radical production, but the enhancement was not statistically significant. At concentrations of 1.25 micrograms/ml and above, there was a profound inhibition of superoxide radical production by these activated cells. Since the products of the respiratory burst, including superoxide, are thought to be inflammatory mediators, it is postulated that the inhibition of superoxide radical generation by gold compounds may be another mechanism by which the compounds modulate their antiinflammatory effects in patients with rheumatoid disease.

Binding Sites↗
PubMed1983

Muscular rehabilitation after orthognathic surgery.

There is both a biologic and a clinical foundation for the use of therapeutic exercise after othognathic surgical procedures to restore normal function of the jaw muscles. This can be accomplished by a systematic plan Of occlusal and muscular rehabilitation after release of maxillomandibular fixation. Through the diligent application of physical therapy principles, the function of the masticatory muscles can be more efficiently rehabilitated after orthognathic surgery and maxillomandibular fixation.

Dental Occlusion↗
PubMed1983

Lumbar spine x-rays: a multihospital study.

To define the usefulness of the lumbar spine x-ray series in the emergency department and to generate clinical criteria for optimizing its application, we retrospectively studied 552 consecutive emergency department patients for whom lumbar spine x-rays were ordered. Patients were divided into traumatic (47.6%) and nontraumatic (52.4%) groups. Three subgroups were created based on radiological findings: 1) "negative" (55.8%), 2) "possibly significant" (37%), and 3) "positive" (7.2%). The "positive" subgroup was compared with the other two subgroups in an attempt to define physical markers that correlated with positive radiological findings. Four clinical findings were present in significantly different frequencies between the positive group and others: an abnormal physical examination (90% vs 61.5%, respectively) (P less than .0001), tenderness (72.5% vs 41.2%) (P less than .0005), multiple positive findings (42.5% vs 20.7%) (P less than .005), and contusion or abrasion (15% vs 2.7%) (P less than .0005).

Adolescent↗
PubMed1983

Metastases to the breast.

Metastases to the breast are uncommon, with about 250 cases reported from clinical and autopsy series. The mammographic findings in 16 new cases revealed a spectrum of changes that included solitary or multiple lesions, well demarcated or poorly marginated masses, and diffuse involvement of skin or parenchyma or both. Diffuse disease was seen more frequently in this series (4/16), at times simulating inflammatory breast cancer. Although diagnosis of a primary malignancy usually preceded detection of the breast lesion, 40% (6/16) had no history of malignancy. Prognosis remains poor; however, it has improved in the lymphoma-leukemia group due to improved immunotherapeutic and chemotherapeutic regimens. The clinical, radiologic, and pathologic features are discussed. Some of the lesions encountered can be confused with a primary breast malignancy or a benign lesion, necessitating prompt and accurate biopsy to preclude unnecessary major surgery and to improve survival in cancers amenable to current therapy.

Adult↗
PubMed1982

A comparison of the mother-child interactions of younger and older hyperactive and normal children.

The mother-child interactions of both younger (means age = 4.11) and older (means age = 8.4) hyperactive children were compared and contrasted with those observed in comparable age groups of normals. Interactions were observed in an unstructured-play and structured-task situation. Mothers of hyperactives were generally more directive and negative during play and less responsive to child-initiated interactions. Hyperactive children asked more questions and were generally more negative and noncompliant during play, particularly younger hyperactives. Hyperactives did not differ from normals in their reactions to mother-initiated behavior during play but engaged in less independent activity when their mothers were noninteractive. During the structured-task situation mothers of hyperactives were more directive and negative and less interactive and approving, even when their child was interacting appropriately. In general, between-group differences in mother-child interactions were greatest when comparing dyads with a younger hyperactive child with the other 3 groups, especially during the structured-task situation.

Age Factors↗
PubMed1981

DNA binding proteins in chromatin structure and function.

The binding of chromosomal proteins to cloned mouse and human globin genes can be determined by transferring proteins from one dimensional electrophoretic separations on to nitrocellulose paper and exposing them to nick translated cloned globin DNAs. The usefulness of this technique is assessed in the case of RNA polymerases isolated from mouse Ascites tumor cells where a specific initiation site for transcription of mouse beta globin DNA can be demonstrated.

Animals↗
PubMed1981

Obstructive sleep apnea in Treacher-Collins syndrome.

Studies of the Treacher-Collins syndrome have emphasized hearing and surgical considerations. Although craniofacial anomalies have been associated with respiratory disorders in infancy, the presence of such problems in older children has not been emphasized. An eight-year-old with Treacher-Collins syndrome presented a history of recent behavioral problems at home, poor attention span and performance in school, daytime somnolence, and sleep apnea with relatively long periods of chest movement but no airflow. He also had abnormal sleep behavior consisting of rocking to and fro on his hands and knees, often to such an extent that his nose became abraded. ICU monitoring with observation and recording of sleep patterns and sounds, and fluoroscopy of his upper airway utilizing cineradiography while asleep confirmed the diagnosis of obstructive sleep apnea. The patient subsequently underwent an orthognathic surgery consisting of insertion of rib bone grafts after anterior advancement of his mandible. This procedure resulted in disappearance of the obstructive sleep apnea and associated symptoms. Because of micrognathia, patients with Treacher-Collins syndrome are at high risk for developing obstructive sleep apnea. Surgical correction of their deformities can result in improvement in cosmetic appearance as well as in resolution of the obstructive episodes with improvement in performance and behavior.

Airway Obstruction↗
PubMed1978

The isolation and partial characterization of low-molecular-weight phosphorylated component of the non-histone proteins of mouse nuclei.

After labelling of mouse liver nuclei with [gamma-32P]ATP in vitro, 10-20% of the radioactivity incorporated into the saline-soluble nuclear and HAP2 chromatin fractions was located in a low-molecular-weight component (component 10) with pI near 4.5 in urea. By using combinations of ion-exchange chromatography, preparative thin-layer isoelectric focusing and gel filtration, this component was isolated from both nuclear fractions. Recovery from the saline-soluble fraction was poor under conditions that allow endogenous phosphatases to be active. Component 10 was shown to be a phosphoprotein on the basis of enzyme-digestion experiments and the detection of phosphoserine and phosphothreonine. The 32P radioactivity did not appear to be associated with phosphorylated basic amino acids. Its molecular weight was determined by gel chromatography and electrophoresis in sodium dodecyl sulphate/polyacrylamide gels as approx. 10000, and tryptic digestion of the reduced carboxymethylated protein in urea yielded two 32P-labelled peptides. It has not been possible as yet to assign a function to component 10, though its similarity to other low-molecular-weight acidic proteins is discussed.

Amino Acids↗
PubMed1977

An analysis of the binding of fluorescence probes in mitochondrial systems.

Measurements of the binding of the fluorescent probes 8-anilinonaphthalene-1-sulfonate (ANS) and ethidium ions to whole and disruped mitochondria and submitochondrial particles suggest that the inner mitochondrial membrane is freely permeable to the two probes. Equations relating the binding of permeant probes to the electro-chemical balance across the membrane of vesicular systems are derived and these equations used to analyze Scatchard plots of the binding of the two probes to energized and nonenergized mitochondria and EDTA particles.

Anilino Naphthalenesulfonates↗
PubMed1977

Equilibrium reaction of pyrazolodiazepinones in aqueous solution.

This study of the behavior of some pyrazolodiazepinones in aqueous solution at near ambient temperature indicated that they form stable equilibrium mixtures consisting of ring and opened forms. Under isothermal conditions, mixtures are produced whose composition is dependent on pH and may vary from that corresponding to essentially complete ring opening to complete closure. Ring closure equilibrium constants were calculated, and the influence of methyl substitution was determined. Substitution of a methyl group for an amido hydrogen in the open form results in a fivefold increase in this constant. Methylation of the terminal amino group, however, did not cause a corresponding increase and may not significantly affect equilibrium.

Azepines↗
PubMed1972

Effects of dibutyryl cyclic adenosine 3',5'-monophosphate and parathyroid extract on calcium and phosphorus metabolism in hypoparathyroidism and pseudohypoparathyroidism.

It has been proposed previously that the metabolic defect in pseudohypoparathyroidism which accounts for parathyroid hormone unresponsiveness is an absence or abnormal form of the adenyl cyclase system in kidney and presumably in bone. To determine whether there is an associated defect in the response mechanism to cyclic adenosine 3',5'-monophosphate (cyclic AMP), the effects of parathyroid extract (PTE), and dibutyryl cyclic AMP were compared in patients with either surgical hypoparathyroidism or pseudohypoparathyroidism. PTE and dibutyryl cyclic AMP both increased serum and urinary calcium, lowered the serum phosphorus, and increased urinary phosphorus in patients with hypoparathyroidism. PTE also increased urinary cyclic AMP in these patients. PTE increased serum and urinary calcium and urinary phosphorus but did not alter serum phosphorus or urinary cyclic AMP in the patients with pseudohypoparathyroidism. Dibutyryl cyclic AMP increased the serum and urinary calcium, lowered the serum phosphorus, and increased urinary phosphorus in all the patients with pseudohypoparathyroidism. The results indicate that (a) dibutyryl cyclic AMP can reproduce the effects of parathyroid hormone on calcium and phosphorus metabolism in man, (b) the response mechanism to cyclic AMP appears to be intact in pseudohypoparathyroidism, and (c) PTE apparently produces some of its characteristic effects on calcium and phosphorus metabolism in pseudohypoparathyroidism in the absence of an increase in urinary cyclic AMP.

Adolescent↗