Showing papers by "Case Western Reserve University published in 1981"

Practical implementation of the double linear damage rule and damage curve approach for treating cumulative fatigue damage

Abstract: Simple procedures are presented for treating cumulative fatigue damage under complex loading history using either the Damage Curve concept or the Double Linear Damage Rule. A single equation is provided for use with the Damage Curve approach; each loading event providing a fraction of damage until failure is presumed to occur when the damage sum becomes unity. For the Double Linear Damage Rule, analytical expressions are provided for determining the two phases of life. The procedure involves two steps, each similar to the conventional application of the commonly used Linear Damage Rule. When the sum of cycle ratios based on Phase I lives reaches unity, Phase I is presumed complete, and further loadings are summed as cycle ratios based on Phase II lives. When the Phase II sum reaches unity, failure is presumed to occur. No other physical properties or material constants than those normally used in a conventional Linear Damage Rule analysis are required for application of either of the two cumulative damage methods described. Illustrations and comparisons of both methods are discussed.

The Regulation of the Mammalian Corpus Luteum

Abstract: Publisher Summary This chapter presents an overview of the regulation of the mammalian corpus luteum (CL) The CL is an ovarian follicle in which the rapid regression—that is otherwise the fate of all postovulatory follicles—is temporarily arrested In the mammalian CL, progesterone secretion goes hand in hand with the postponement of regression It is fairly certain that reptilian CL also secretes progesterone The mammalian CL is formed during the period around ovulation by a transformation of the cells lining the cavity of the follicle Luteinization affects the granulosa cells in all species It involves an enormous enlargement of the cell with a great increase in the nucleus–cytoplasm ratio and the formation of a very distinct cell wall, the development of an extensive capillary network enmeshing all the cells, a marked proliferation of the endoplasmic reticulum, and its transformation from a predominantly rough to a predominantly smooth type, a marked proliferation of the mitochondria from a small round or rod shape type with lamelliform cristae into larger and more varied shapes with tubular and villiform cristae, and an increase in the complexity of the Golgi apparatus The CLs activity differs most from that of the follicle in how much rather than in what kinds of steroid it makes The principal change is a striking increase in progesterone secretion, accompanied by a variable, but severe fall or even loss of the capacity for estrogen and androgen secretion

Falciparum malaria-infected erythrocytes specifically bind to cultured human endothelial cells

Abstract: Erythrocytes infected with the late stages of the human malarial parasite Plasmodium falciparum became attached to a subpopulation of cultured human endothelial cells by knoblike protrusions on the surface of the infected erythrocytes. Infected erythrocytes did not bind to cultured fibroblasts; uninfected erythrocytes did not bind to either endothelial cells or fibroblasts. The results suggest a specific receptor-ligand interaction between endothelial cells and a component, components, in the knobs of the infected erythrocytes.

Experiential Learning Theory and The Learning Style Inventory: A Reply to Freedman and Stumpf

Abstract: Freedman and Stumpf's critique of experiential learning theory and the Learning Style Inventory (LSI) is seriously flawed. Their judgments concerning the validity of experiential learning theory rest primarily on an analysis of the internal characteristics of the LSI, with no attention to the construct validity of that instrument; and they are made without analysis or even awareness of the considerable research literature on experiential learning. Their questions concerning the reliability of the LSI stem from a lack of understanding of the role of variability and situational adaptation in the experiential learning process. Similarly, their criticism of the forced-choice format of the LSI fails to recognize the theoretical rationale for the LSI instrument structure.

Vitamin D and Its Metabolites in Human and Bovine Milk

Abstract: Human and bovine milk were analyzed for vitamin D, 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, 25,26-dihydroxyvitamin D and 1,25-dihydroxyvitamin D using exhaustive chromatographic purification procedures coupled with ligand binding assays. Human milk contained the following amounts of antirachitic sterols (pg/ml, mean +/- SD, n = 5): 39 +/- 9 vitamin D; 311 +/- 31 25-hydroxyvitamin D; 52 +/- 8 24,25-hydroxyvitamin D; 32 +/- 9 25,26-dihydroxyvitamin D; 5.1 +/- 0.3 1,25-dihydroxyvitamin D. Normal bovine milk contained levels of these sterols comparable to those found in human milk. Increasing the oral dose of vitamin D to the cows was reflected by an increase of the parent vitamin and 25-hydroxyvitamin D in the milk. Vitamin D-binding protein concentration in human milk whey, determined by Ouchterlony immunodiffusion and radioimmunoassay, was 1--2% of the levels observed in the plasma and was dependent on the stage of lactation. Vitamin D and its metabolites were shown initially to be present in the whey portion but with time migrated into the fat portion of milk. The antirachitic sterols detected account for approximately 25 IU/liter and 27 IU/liter of antirachitic activity in human and bovine milk, respectively. In both species 25-hydroxyvitamin D comprised the majority of the antirachitic sterols detected in normal milk.

Miocene Stable Isotope Record: A Detailed Deep Pacific Ocean Study and Its Paleoclimatic Implications

Abstract: Deep Sea Drilling Project site 289 in the western equatorial Pacific has yielded an extremely detailed record of the carbon and oxygen isotopic changes in the Miocene deep ocean. The isotopic record reflects major changes in paleoclimate and paleoceanography, probably dominated by a major phase of Antarctic ice-cap growth. The transition from a relatively unglaciated world to one similar to today occurred between 16.5 x 10(6) and 13 x 10(6) years before the present, with the greatest change occurring between approximately 14.8 x 10(6) and 14.0 x 10(6) years before the present.

Axonal guidance during development of the optic nerve: The role of pigmented epithelia and other extrinsic factors

Abstract: It is well established that a congenital lack of ocular melanin (albinism) can lead to developmental abnormalities of the central visual pathways. However, it is yet unknown how the pigmentation per se acts to influence formation of the optic projection. In order to study the possible interaction between eye pigment and optic axons during development, we have examined, with the use of serial section techniques, a series of timed embryos at stages when the ocular pigment and outgrowing axons first become apparent. Our results have demonstrated that, in mice and rats, the upper wall of the distal half of the primitive eye stalk (a region which lies along the potential route to be taken by the earliest developing nerve fibers) is transiently pigmented prior to and during the migration of the pioneer optic axons. All outgrowing neurites avoid this stretch of melanotic tissue and instead grow preferentially through a system of extracellular tunnels in the ventral, pigment-free zones of the distal eye stalk. The stalk remains unpigmented from about its midpoint and continuing toward the brain. At the pigment/pigment-free interface many of the axons shift upward from their ventral positions, forming a marginal annulus. In the chick, on the contrary, pigmentation of the stalk does not occur and as the optic axons exit the globe they grow immediately in an annulus configuration. In Xenopus, the entire stalk becomes pigmented and the optic fibers congregate in one discrete bundle of fascicles along the length of the stalk's most ventral margin. These observations suggest that melanin-producing stalk cells may play a role in controlling the topographic patterning of optic fibers within the developing nerve by inhibiting the lateral spread of axonal growth cones into or within their territory. To test this hypothesis we have charted the distribution of optic fibers in the developing optic stalks of timed albino rat embryos. Indeed, as fibers leave the mutant eye, it was found that a small but consistent number of pioneering axons (day E15) become ectopic and immediately invade nonpigmented regions (those normally pigmented and axon-free) in the distal optic stalk. Thus, the usual topographic arrangement of the collection of pioneer optic fibers is altered in the albino.

Neurosecretory granules in small cell invasive carcinoma of the urinary bladder

Abstract: A 69-year-old man showed symptoms of urinary bladder irritability and hematuria. Cystoscopy and radiographic studies revealed a tumor within a bladder diverticulum. The tumor shared histologic and ultrastructural features with oat cell carcinoma of the lung, including the presence of small numbers of neurosecretory type granules. In spite of conservative surgical treatment, there has been no evidence of recurrent or metastatic tumor over 14 months of follow-up. Hypophosphatemia was present preoperatively, but resolved spontaneously after tumor resection. In regard to histogenesis, a metaplastic origin is favored. This appears to be the first reported case of a neoplasm of Kultschitzky-type cells arising in the urinary bladder.

Central nervous system toxicity of high-dose systemic cytosine arabinoside

Abstract: Forty-nine adult patients with acute leukemia in relapse, refractory to conventional therapy, were studied. Increasing quantities of i.v. bolus high-dose cytosine arabinoside (cytarabine) were administered using the following schedules: 3 g/m2 every 12 hrs for 4-16 consecutive doses, or 4.5 g/m2 every 12 hrs for 12 consecutive doses. Patients ages ranged 16-76 year (median: 38). Thirty-seven patients had previously received either induction or maintainance therapy with conventional doses of cytarabine. Cerebral or cerebellar dysfunction attributable to cytarabine was observed in eight patients and appeared 6-8 days (mean: 6.6) after the first dose and lasted 3-7 days (mean: 4.7). None of 12 patients receiving up to 24 g/m2 total dose of 48 g/m2 developed reversible neurologic dysfunction. Four of six patients receiving 54 g/m2 developed CNS toxicity (irreversible in two cases), a significantly greater incidence compared to toxicity in patients receiving less than or equal to 48 g/m2 total dose (P less than 0.01). CNS toxicity was dose-related since patients treated for 12 consecutive doses of 4.5 g/m2 had significantly greater CNS toxicity than 12 consecutive doses at 3 g/m2 (P less than 0.04). Systemic cytarabine doses less than 54 g/m2 can be administered with minimal CNS side-effects.

Effect of Warfarin on Survival in Small Cell Carcinoma of the Lung: Veterans Administration Study No. 75

Abstract: In a controlled, randomized study, survival of patients with small cell carcinoma of the lung (SCCL) was prolonged on addition of warfarin sodium to combination chemotherapy plus radiation therapy. Median survival for 25 control patients was 24 weeks and for 25 warfarin-treated patients was 50 weeks. This difference could not be accounted for by differences between groups in performance status, extent of disease, age, or sex. The survival advantage associated with warfarin administration was observed both for patients with extensive disease and for those who failed to achieve complete or partial remission. The warfarin-treated group also demonstrated a significantly increased time to first evidence of disease progression. These results suggest that warfarin may be useful in the treatment of SCCL and also support the hypothesis that the blood coagulation mechanism may be involved in the growth and spread of cancer in man. ( JAMA 1981;245:831-835)

Psychologic functioning of siblings of disabled children.

Abstract: This paper reports findings from a comprehensive study of families of pediatric patients with cystic fibrosis, cerebral palsy, myelodysplasia, and multiple handicaps receiving care in clinics of two teaching hospitals in Cleveland. In 239 families with normal siblings 6 to 18 years old, mothers completed the Psychiatric Screening Inventory for a randomly selected sibling in this age group. Results were compared to data on 1,034 randomly selected children from a cross-section of Manhattan households. The proportion of siblings with serious impairment was not significantly different from the Manhattan sample. Although on the total inventory siblings did not score significantly higher than the comparison sample, they did score significantly higher on the mentation problems, fighting, and delinquency subscales. The diagnostic categories of the disabled children had no significant effect on siblings9 scores, nor did level of disabiity. Neither siblings9 sex nor age bore any relationship to their psychologic functioning. A sibling9s birth order in relation to the disabled child had a significant interaction effect with sex on psychiatric impairment. Little relationship was found between a mother9s perceived effects of caring for a disabled child on attention to siblings and siblings9 disorder.

Bodian's silver method stains neurofilament polypeptides

Abstract: Bodian's silver method was used to stain polypeptides of rat spinal cord or peripheral nerve separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The bands corresponding to the t...

When rational men fall sick : An inquiry into some assumptions made by medical anthropologists

Abstract: Medical anthropologists spend most of their time eliciting and interpreting people's statements about sickness and health. For this task, they make certain assumptions about the importance of language and reason. In this paper I argue that their assumptions are tailored to fit an hypothetical Rational Man rather than real people. The concept of ‘explanatory models of sickness’ is used to illustrate this point. My critique begins by drawing attention to two non-cognitive determinants of people's statements: their degree of emotional arousal and their capacities for discoursing on medical subjects. These determinants are briefly discussed and then set aside, to make room for the paper's argument proper. This starts with the observation that medical anthropologists tend to overlook the fact that they have established a cognitive no man's land stretching between their informants' statements and the cognitive structures which are supposed to generate these statements. I survey this void, using a five-fold model of medical knowledge. People use one kind of knowledge to organize their medical experiences and perceptions. In Rational Man writing, this form of knowledge is considered equivalent to cognitive structures (e.g., causal models, classificatory schemes), but I argue that it also includes knowledge of prototypical sickness events and knowledge that is embedded in actions, social relations, and material equipment. The theoretical implications of the five-fold model are outlined. This is followed by an analysis of the reasoning processes in which people use medical knowledge to produce the statements whose meaning we wish to learn. I demonstrate the importance of being able to distinguish operational and monothetic forms of reasoning from pre-operational and polythetic ones. Rational Man writers are described as ignoring the latter pair. The concept of ‘prototypes’ is reintroduced to illustrate these points.

The Width of Keratinized Gingiva During Orthodontic Treatment: Its Significance and Impact on Periodontal Status*

Abstract: This study was performed to evaluate the effects of orthodontic therapy on the width of the zone of keratinized gingiva. Pre- and post-treatment photographic slides, plaster study casts, and cephalograms were examined. The labial surfaces of 966 teeth in a sample of 100 orthodontic patients were studied. Widths of the keratinized gingiva were determined from photographic slides. Crown lengths were measured from the study casts, and measurements were performed on the cephalograms. Data were collected and analyzed in three categories: 1) The overall changes in the width of the keratinized gingiva and the lengths of the clinical crowns during the course of orthodontic therapy; 2) An analysis of grouped data with a comparison of the pre-existing widths of keratinized gingiva to the post-treatment periodontal status of the patient; and 3) A correlation analysis of the changes in the dimensions of the tissues to the changes in tooth position as measured on the cephalograms. The results of the study revealed: 1)...

State of the Art: Laboratory Strength Testing of Soils

Abstract: A review and evaluation of the advantages and limitations of laboratory equipment for measuring the shear strength of soils are presented. Equipment evaluated include direct shear, torsional shear, simple shear, triaxial,multiaxial (true triaxial), plane strain, hollow cylinder triaxial, and directional shear devices. The evaluation indicates that the impetus to obtain parameters for constitutive equations and modeling has resulted in the development of improved equipment and testing techniques; specifically, the development of multiaxial (true triaxial) and hollow cylinder triaxial test equipment. Although these devices are more versatile, the conventional solid cylinder triaxial test is still the most popular. The evaluation suggests that direct shear and simple shear devices are best utilized by designers who have gained experience applying the results from such tests to structures that have behaved satisfactorily. Proper consideration must be given to the effects of membrane penetration, end restraint saturation and consolidation procedures, and rates of loading in any testing program.

Photosynthesis-deficient Mutants of Chlamydomonas reinhardii with Associated Light-sensitive Phenotypes.

Abstract: A series of non-photoautotrophic mutants of Chlamydomonas reinhardii was isolated by replica-plating mutagenized cells which had been grown in the dark. Many of these acetate-requiring mutants are photosensitive, showing poor growth on acetate medium in the light, but normal growth in the dark. Biochemical characterization showed that the photosensitive mutants all had specific lesions in photosynthesis or photosynthetic pigment accumulation. The acetate-requiring mutants which were not photosensitive were all able to fix CO(2). Among the light-sensitive mutants are 15 which show uniparental inheritance. These include six with specific lesions in photosystem II and one with an altered large subunit of ribulose-1,5-bisphosphate carboxylase. Since these two classes of uniparental mutants have been rare or not previously reported, it seems likely that photosensitivity is an important factor which limited their detection in previous mutant isolation experiments.