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T Allen

Publications and source records attributed to T Allen.

At least 91 records · Page 5Linked to original sources
PubMed1979

Suspected esophageal foreign body -- choosing appropriate management.

Twenty-two cases of probable esophageal or pharyngeal foreign body seen at an emergency service were studied retrospectively, using 15 predetermined factors chosen to detect or anticipate the acute consequences of foreign body ingestion. Three findings were particularly predictive: 1) foreign body visualized directly or on plain x-ray films; 2) hypersalivation; 3) obstruction or foreign body image in the esophagus on barium swallow. No patient with none of these three abnormal findings, even in the presence of localized pain increased by swallowing, received further treatment, and no complications developed. All patients with any one of these three findings underwent direct foreign body removal (four cases) or esophagoscopy (11 cases). Five esophageal foreign bodies passed spontaneously into the stomach before esophagoscopy; four foreign bodies were removed, and two esophagi were abnormal (stricture, myasthenia gravis). In two cases no foreign body was found. Hypersalivation was the only finding always associated with an abnormal esophagoscopy. Particular attention must be paid to the interpretation of plain x-ray films, with regard to probable foreign body location at the cricopharyngeal constriction and to indirect signs such as fluid levels, soft tissue swelling, free air, if small foreign bodies are not to be missed.

Adult↗
PubMed1977

Postsynaptic membranes in the electric tissue of Narcine: II. A freeze-fracture study of nicotinic receptor molecules.

The ventral, postsynaptic membranes of the electroplaques of Narcine were found to containe intramembranous particles similar in location, packing density (about 5700/micron 2), transmembrane position and end appearance to nicotinic acetylcholine receptor-channel molecules. In fixed tissue the particles were limited to the cytoplasmic lamina, while in unfixed tissue an equivalent number were found symmetrically in both laminae. Four populations of particle diameters were observed in each unfixed lamina, even though other morphological evidence indicates the presence of large number of molecules of uniform structure, and biochemical studies of isolated postsynaptic membranes indicate that at least 70% of the membrane protein is receptor-channel protein. Intramembranous particles in dorsal, non-innervated electroplaque membranes, presumably representing Na+, K+-associated ATPase and other channel proteins, were found to have similar characteristics to particles in ventral membranes. Receptor-channel molecules cannot, therefore, be distinguished from other intrinsic membrane proteins by freeze-replication alone.

Animals↗
PubMed1977

Postsynaptic membranes in the electric tissue of Narcine: III. Isolation and characterization.

Postsnyaptic membranes in homogenates of the electric tissue of Narcine were identified by labelling nicotinic acetylcholine receptors in the membranes with radioactive alpha-bungarotoxin. Various media and centrifugation conditions were examined in an attempt to obtain highly purified postsynaptic membranes. The main criterion for purification was approach towards the specific activity of the pure receptor protein, 9--10 nmol toxin-sites/mg protein. Isolation of tissue microsomes with Tris buffer, EDTA and the protease inhibitor phenylmethylsulfonylfluoride (PMSF), conditions which preserve the receptor molecules optimally, yielded about 50% of the tissue toxin-sites, 5% of the protein, 4% of the ATPase and less than 2% of the acetylcholinesterase (AChE). Further separation of vesiculated membranes in continuous density gradients of sucrose showed that the major contaminants of postsynaptic membrane vesicles were damaged mitochondria and tubular vesicles of dorsal electroplaque membranes rich in ATPase. Mitochondria were effectively removed from homogenates by 'differential' centrifugation, and ATPase-rich vesicles could be largely removed by causing their agglutination with calcium ions, or by controlled proteolysis in the absence of PMSF. Partially purified postsynaptic membranes were obtained having about 7 nmol toxin-sites/mg membrane protein. Further purification appears possible by affinity techniques.

Animals↗
PubMedDate not supplied

Increased arterial stiffness in children with a parental history of hypertension.

The vascular dynamics of children with a parental history of hypertension has not been defined. The purpose of the current study was to determine whether or not these children have different arterial stiffness compared to the offspring of normotensive parents. One hundred healthy, nonobese subjects (ages 10-21 years) were divided into two groups of 50. Group A included the offspring of hypertensive patients and group B the offspring of normotensive parents. The variables studied were body surface area, blood pressure, and systolic and diastolic diameters of the aortic and carotid arteries as well as maximum velocity flow of these vessels. Carotid and aortic stiffness were calculated. Children and adolescents with a parental history of hypertension had higher carotid stiffness and smaller carotid diameters. These differences continued to be significant when correcting for body surface area. A higher blood pressure and a greater body surface area were also found.

Adolescent↗
PubMedDate not supplied

Cells expressing ENOD2 show differential spatial organization during the development of alfalfa root nodules.

We have used in situ hybridization to examine the spatial organization of cells expressing the early nodulin gene (ENOD2) during the development of alfalfa root nodules. ENOD2 gene expression was found in the nodule parenchyma, uninfected cells surrounding the symbiotic region of both effective and ineffective nodules. However, in empty nodules, ENOD2 gene expression was found in a mass of parenchyma cells at the base of the nodule. Similar results were also observed in 11-day-old nodules that contained infected cells but that had not yet begun to express leghemoglobin. Although early events of nodulation result in the induction of ENOD2 expression in cells at the nodule base, the pattern of cells expressing ENOD2 during nodule growth appears to be correlated with the development of other peripheral tissues.

Fabaceae↗