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Biomedical subjects

P Larsen

Publications and source records attributed to P Larsen.

At least 55 records · Page 3Linked to original sources
PubMed1980

Upper limb anomalies and renal disease.

Two brothers with upper limb and renal anomalies have been identified. Their upper limb abnormalities were characterized by absence and hypoplasia of various bones; their renal anomalies included crossed-fused ectopia and vesico-ureteral reflux. Both suffered from chronic kidney failure secondary to reflux nephropathy. An autosomal or sex-linked mode of inheritance seems likely.

Abnormalities, Multiple↗
PubMed1974

Sulfhydryl groups of the erythrocyte membrane and their relation to glycolysis and drug-induced hemolytic anemia.

Hemolytic anemia caused by oxidative drugs is thought to result from the oxidation of intracellular and membrane sulfhydryl groups of the erythrocyte. This process is more likely to occur in those erythrocytes in which the intracellular mechanism for reduction of disulfides is abnormal (e.g., glucose-6-phosphate dehydrogenase deficiency). If a membrane sulfhydryl group is critical in the pathogenesis of druginduced hemolytic anemia, it follows that this specific group must be dependent on intracellular reductive mechanisms for maintenance of the reduced state. This report describes a sulfhydryl group(s), involved in membrane structure, which is (are) dependent on intracellular metabolism for maintenance of the reduced state. It is postulated that this metabolically dependent membrane sulfhydryl group may play a role in the pathogenesis of drug-induced hemolytic anemia. Membrane sulfhydryl groups were studied by observing the effect of sulfhydryl blocking agents, e.g., N-ethyl-maleimide (NEM), on the recovery of erythrocyte ghosts after osmotic lysis. It was shown that NEM interfered with ghost recovery by reacting with membrane sulfhydryl groups. The concentration of NEM (as determined by [(14)C] NEM binding) necessary to cause this effect was lower than that necessary to produce changes in osmotic fragility or cation permeability, or to cause Heinz body formation. In the absence of glucose, these sulfhydryl groups became disulfides, but could be returned to the reduced state by restoring glycolysis or by adding dithiothreitol. Phenylhydrazine hemolytic anemia was induced in pigs, and membrane changes of the type described above occurred early in the pathogenesis of the disease.

Anemia, Hemolytic↗
PubMed1973

Gravity sensing by plants.

A brief description of the effects of gravity on plants, particularly their orientation with reference to its direction, is followed by a presentation of evidence for the operation of specific "gravity sensors", statoliths, subcellular bodies which move or reorient themselves upon reorientation of a plant organ with respect to the direction of the force of gravity. In the singly reacting apical cells of rhizoids of Chara, the statoliths locally regulate the growth of the cell wall simply by blocking or permitting the access of carriers of cell wall material. In multicellular structures (root and stem tips etc.) the statoliths, most likely amyloplasts (starch-containing plastids), must act by creating in the organ a transversal polarity which can be transmitted to the growing region, often several millimetres away. In addition, gravity produces what may be called tonic effects, which quantitatively modify the reaction of the organ to the gravitational stimulation.

Chlorophyta↗
PubMedDate not supplied

Terminal restlessness in the nursing facility: assessment, palliation, and symptom management.

Terminal restlessness, sometimes called agitated delirium, is a common occurrence at the end of life. This type of delirium may appear as thrashing or agitation, involuntary muscle twitching or jerks, fidgeting or tossing and turning, yelling, or moaning. Among older adults, especially those in long-term care situations, the delirium may not appear to be very different from previous episodes observed when the resident experienced an infection, exacerbation of a chronic condition, anxiety, pain, or adverse drug reactions. However, delirium at the end of life is usually multifactorial and exacerbated by the progressive shutdown of multiple body systems. Therefore, the effective management of terminal restlessness requires a different approach than the usual care of residents with delirium. For many nurses, this responsibility means adding new clinical knowledge and skills to their practice inventories. This article provides an overview of terminal restlessness, offers assessment guidelines for older adults in long-term care situations who are dying, and describes comfort and symptom management strategies for these individuals.

Geriatric Assessment↗
PubMedDate not supplied

Experimental long-term tubal occlusion in cats. A quantitative histopathological study.

Unilateral tubal occlusion was performed in 10 cats, which were sacrificed 26-44 months later. During the observation period repeated bilateral tympanometry and auditory nerve response were recorded. Paracentesis with evacuation of effusion was performed up to eight times and the effusion was examined by viscometry. After sacrifice, quantitative histopathology of the bulla with determination of goblet cell density was carried out. In three ears having glue at the last paracentesis, the histopathologic changes were more pronounced than in the four ears having thin effusion. Three ears were dry at sacrifice with normal tympanometry, the histopathological changes evidently demonstrate the the normalization of the middle ear mucosa. The experiments demonstrate the great importance of tubal patency or function in prognosis of the disease. In ears with anatomically occluded tubes, no recovery occurred, whereas in ears with normalized tubal function, the middle ear mucosa and goblet cell density also normalized. Pathogenic and etiological aspects of secretory otitis are discussed.

Acoustic Impedance Tests↗
PubMedDate not supplied

Anomalies of craniofacial skeleton and teeth in cleidocranial dysplasia.

Mutations involving the transcription factor CBFA1 cause cleidocranial dysplasia (CCD) in man. Recently, a mouse model of CCD has been generated (Cbfal +/-) [Komori et al., 1997], and disturbances of osteoclast differentiation have been documented. It has been shown that these animals exhibit hypoplastic clavicles and nasal bones, and retarded ossification of parietal, interparietal, and supraoccipital bones. Humans with CCD show all these features, including severely retarded ossification of the cranial base, strongly suggesting that both intramembranous ossification and endochondral ossification are affected. In addition, CCD patients have multiple supernumerary teeth and delayed tooth eruption. The present report presents 3D reconstructions of computerised tomography (CT) scans of the craniofacial region of a CCD boy examined at both 1 and 7 years of age. The anomalies in craniofacial skeleton and teeth are analysed and compared to the findings of our previous clinical studies and to the findings in the animal model. Based on the available information, we suggest that osteoblast, osteoclast, and dentinoclast differentiation may be disturbed in CCD.

Child↗
PubMedDate not supplied

The effects of nitrous oxide on behavior and physiological parameters during conscious sedation with a moderate dose of chloral hydrate and hydroxyzine.

The purpose of this study was to determine differences in heart rate (HR), blood pressure (BP), peripheral oxygen saturation (pO2), expired CO2 (CO2), and behavior (using two scales) comparing nitrous oxide/oxygen (N2O) with oxygen (O2) alone in 20 children (mean age 45 +/- 5.1 months) sedated with chloral hydrate (CH) and hydroxyzine in a double-blind crossover design. Administration of CH (40 mg/kg) and hydroxyzine (2 mg/kg) was held constant for each patient visit; however, N2O (50%) was administered during one visit and O2 (100%) at the other in a randomly determined manner. Physiologic and behavioral parameters were collected during eight specific procedural events (e.g., administration of local anesthesia). Data were analyzed with a repeated-measures ANOVA, one-way ANOVA, t-test, Kruskal Wallis ANOVA, and descriptive statistics. There was no statistically significant difference in any physiologic or behavioral parameter as a function of inhalation agent. However, significant differences were found for certain physiological parameters (i.e., HR [F = 5.41, P < 0.001], pO2 [F = 6.04, P < 0.001], and CO2 [F = 2.33, P < 0.027]) and all behavioral measures (% crying [F = 2.82, P < 0.008], % quiet [F = 5.38, P < 0.001], % movement [F = 3.88, P < 0.001], and % struggle [F = 2.83, P < 0.007]) of one scale (Ohio State University Behavioral Rating Scale [OSUBRS]) as a function of procedural events. Although no statistically significant differences were attributable to inhalation agent, evidence suggests that N2O resulted in less crying and struggling and more quiet behaviors than O2. Significant correlations existed between sub-categories of the two behavioral rating scales, suggesting some association between the scales. One may conclude from the results of this study that moderate doses of CH and hydroxyzine in combination with nitrous oxide are not associated with any significant potentiation effects on physiologic parameters compared with the same oral agents with oxygen alone. Certain procedural events (e.g., administration of local anesthesia) do result in patient responses that affect specific behaviors and physiology. Although the effects of N2O may not be statistically significant, generally it produces an attenuation in physiological and behavioral responses as measured under the conditions of this study.

Analysis of Variance↗
PubMedDate not supplied

Comparison of resorbable and nonresorbable guided bone regeneration materials: a preliminary study.

The purpose of this study was to compare bone regeneration within a surgically created defect using three different resorbable membranes (polyglactin 910 knitted mesh/Vicryl, freeze-dried fascia lata, and crosslinked bovine type I collagen/BioMend) and two nonresorbable membranes (expanded polytetrafluoroethylene/Gore Tex, and polytetrafluoroethylene/Millipore). Each of three adult male dogs underwent surgical preparation of six bicortical defects of the calvarium, each 1.5 cm in diameter. The experimental barrier membranes were placed on both sides of the defects (inner and outer cranial tables). Five of the six defects were covered randomly by one of the five membrane materials, and one was left uncovered to serve as a negative control. The animals were sacrificed 10 weeks after membrane placement. Bone response was measured clinically, as well as radiographically, via densitometric examination. All surgical sites healed uneventfully. Variable degrees of new bone growth were present at all sites when evaluated by both clinical and radiographic examination. The general trend of observed osseous response indicates a greater, although not statistically significant, degree of bone growth using nonresorbable membranes. The animal model employed appears to be an efficient and reliable means of evaluating guided bone regeneration membranes.

Animals↗