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Results for “Origin--determinants”

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At least 55 records · Page 3Linked to original sources

PubMed1988

Pursuit and saccadic eye movements in response to unpredictable constant velocity targets.

Pursuit eye movements in response to unpredictable reversals of constant velocity target motion at 20 degrees, 40 degrees and 60 degrees/s were analysed in 20 normal subjects. The gain in smooth pursuit was originally determined by the preceding target duration; the shorter the preceding movement, the longer was the acceleration of pursuit velocity inhibited. The ongoing target duration secondarily affected the gain at faster target velocities by restricting time for eye velocity acceleration. Whereas the saccadic reaction time was around 200 ms, the intersaccadic interval shortened as target velocity increased. The saccadic amplitude increased in direct proportion to an increase in target velocity. The present study showed that, even under irregular stimulations, pursuit eye movement is regulated in a feedforward manner by the perceptual analysis of the preceding target motion, and that corrective saccades in pursuit eye movement correspond to those observed in step displacements, except for the programming on the basis of the changing rate of position error.

Adult↗

PubMedDate not supplied

A practical approach to coma diagnosis in the unresponsive patient.

Diagnosis of coma in the unresponsive patient can be done in a relatively short time by making key observations that will confirm disease of either the brain stem or the hemispheres, the two locations in which coma originates. Determining the location of the lesion is the primary goal in early assessment of the unresponsive patient. Examination of the patient's eyes is the single most important step in understanding coma.

Brain Stem↗

PubMed1975

Rejection and repair of endothelium in major vessel transplants.

Fresh saphenous vein homografts are gaining popularity as conduits for femoral-popliteal or distal bypass grafts. Aside from major blood group compatibility, there is little clinical evidence that rejection is a significant factor in long-term patency. Some have suggested that blood vessels are weakly antigenic and others indicate that rejection does not endanger long-term patency. Transplantation and toxic damage were produced in experimental animals in order to compare healing processes. Both types of injuries produced early significant endothelial cell proliferation detected by H3-thymidine uptake. This response peaked at 5 days in transplants and ever-expanding islands of proliferating endothelium were present in aortas exposed to 20 percent sodium chloride, leading to healing in 3 to 4 months. In the transplanted vessels, total endothelial destruction occurred at 11 to 28 days, and cells of host origin determined by sex chromatin analysis gradually resurfaced those grafts that maintained patency. At 4 months only two of six carotid artery homografts were patent in unmodified dogs, and eight of nine were patent in animals given 1 mg. per kilogram of Imuran. All patent grafts were resurfaced by host cells. We conclude that rejection does play a role in long-term patency; that donor endothelium of living vascular grafts cannot maintain sufficient proliferative capacity to repair immunological damage; that small doses of Imuran significantly alter the rate of destruction leading to more orderly repair and patency; and that clinical trials utilizing one half the dose of Imuran required for kidney graft survival are likely to improve significantly the long-term patency rate of fresh arterial or venous homografts in man.

Animals↗

PubMed1989

Biological determinants in implant design.

This paper considers whether fibro-osseous integration is a feasible outcome for dental implants and whether the mucosal-implant junction is a crucial factor for implant success. It is argued that the periodontal ligament is a connective tissue with specific origin determined early in development. Further, it is argued that fibroblasts of the ligament exhibit unique functional characteristics associated with tooth support and that these characteristics cannot, as yet, be duplicated in other fibroblasts. These specific attributes argue against the feasibility of fibro-osseous integration unless cells of the periodontal ligament are available to develop a fibrous attachment. With respect to the dentogingival junction, it is argued that this structure does not provide a functional seal around the normally functioning tooth and therefore a minor degree of inflammation in the connective tissue adjacent to an implant is acceptable. It is also argued that inflammation associated with fibro-osseous integrated implants is not the result of a deficiency in the epithelial attachment but rather is due to the inability of the connective tissue to withstand the forces applied to it.

Dental Implantation, Endosseous↗

PubMed1989

[Glass ionomers--types and clinical application].

With the formation of the glassionomers one wanted to combine the major qualities of the silicate cement, the composite resins and the polycarboxylate cement. The greatest advantages are bonding to tooth structure, the release of fluorides and thereby an inhibition of secondary caries, and a thermal coefficient similar to tooth structure. The glassionomers are more compatible to the pulp than the old silicates. The bonding to tooth structure is increased through pretreatment where polyacrylic acid is most recommendable. Today there are two major types of glassionomers: the water-based which contain freeze-dried acid in the glass powder, and the original, determined by the addition of an aqueous solution of polyacrylic acid to the glass powder. Certain types are delivered in premeasured capsules for mechanical blend, which decreases the sensitive handling of the material. The use of glassionomers serves a number of purposes and will properly be more widespread in the future, especially the concern of lining in combination with composite resins, the metal-reinforced to crown-buildup and the luting types, when the considerations about earlier hypersensitivity after luting of castings is clarified. The restorative types shows better promising results than composite resins in Class V restoration.

Dental Bonding↗

PubMedDate not supplied

Influence of dietary calcium stress on lethality of avian influenza viruses for laying chickens.

The effect of calcium stress was studied in an attempt to reproduce lethal infections in laying chickens with A/Chicken/Alabama/75 (H4N8) influenza virus and with two nonpathogenic H5N2 influenza viruses from the 1983-84 outbreak in the eastern United States. Hens were fed calcium-deficient or standard diets for 7 to 14 days; then the calcium-deficient feed was replaced with standard feed supplemented with ad libitum oyster shell, and both groups of hens were inoculated with virus. When hens were infected with the H4N8 virus, respective mortalities of those on the calcium-deficient and standard diets were 19% (27/141) and 5% (7/143). The H5N2 viruses did not kill hens fed either diet. In standard pathogenicity tests, Alabama H4N8 viruses reisolated from the hens that died generally were more lethal for 4-week-old chickens than the stock virus. These results argue for characterization of the Alabama H4N8 virus as pathogenic rather than nonpathogenic as originally determined.

Animals↗

PubMed1988

Pesticide residue control in the years 1980-1982.

Data on pesticide residue on vegetables, fruits, cereals, and other foods of vegetable or animal origin determined by Provincial Laboratories during the years 1980-1982 are presented and compared with levels permitted by Italian legislation. An analysis of the results obtained from about 3000 samples shows that a high percentage of samples did not contain detectable pesticide residues or had residue levels below the maximum allowed by Italian law: 98% of the vegetables, 94.6% of the fruit, and 97.5% of the cereals (fumigants not considered here). On fruit, some residues exceeding the permissible levels for postharvest compounds, i.e., ethoxyquin, ethylenebisdithiocarbamate (EBDC), and benzimidazolmethylcarbamate (BMC), were found in apples and pears. Residue levels of some organochlorinated compounds slightly exceeding the legal limit were observed in some food samples of animal origin (mainly cow's milk). Comparing the present results with those of previous studies indicates that there has been a general decline in the residue levels of aldrin/dieldrin in milk and milk products.

Edible Grain↗

PubMed1986

Comparison of two techniques for quantitation of encysted cyathostome larvae in the horse.

Haustral portions of intestine of 6 horses were isolated by excising the taeniae coli from the cecum and the ventral colon. Uniform 5-cm X 5-cm sections were cut from the haustra and were illuminated from the serosal side with a strong light source (mural transillumination). Cyathostome larvae encysted in the mucosa and submucosa were observed at 15 X magnification and counted. Two separate counts of the larvae in 80 replicates of tissue by the mural transillumination technique (MTT) revealed no significant (P less than 0.05) difference between sample means. Larvae in tissue sections were counted in situ by MTT, and the mucosal scrapings of the tissue sections were digested in pepsin and HCl to determine larval yields for comparison with the MTT counts. Numbers of larvae recovered by pepsin and HCl digestion for 3 and 6 hours were significantly (P less than 0.01) lower than were numbers originally determined by MTT. Larvae recovered by tissue digestion for 3 or 6 hours were examined individually and given objective scores for morphologic damage. Distribution of scores was time-dependent; increased damage to larvae was associated with a longer time of digestion. Individual 4th-stage cyathostome larvae were dissected from cysts in the large intestinal wall and were incubated in water, 0.9% saline solution, 1.1% HCl, or pepsin (7,000 U of activity/ml). Significantly fewer (P less than 0.05) larvae were recovered from all solutions after 3 and 6 hours. The proportion of dissected larvae that were given high scores after exposure to pepsin was significantly (P less than 0.01) greater than were those held in HCl, saline solution, or water for both periods.

Animals↗

PubMedDate not supplied

Cardiorespiratory adjustments in chronic sickle cell anemia.

During the intercrisis periods, patients homozygous for sickle cell anemia (SS) show clinical symptoms of severe impairment of oxygen transport mechanisms. We have determined respiratory lung function tests, arterial and venous blood gases and cardiocirculatory parameters in 39 SS patients (mean age 22 +/- 5 yr) at distance from any vaso-occlusive crisis or blood transfusion. The patient group was compared to subjects homozygous for HbA (AA) of the same ethnic origin. Determinations were made at rest and after a 5 min mild exercise period. The main alterations in oxygen transport parameters observed in SS patients were: 1) a moderate reduction in vital capacity and maximal ventilation (pure restrictive syndrome), 2) an arterial hypoxemia which worsened the already low oxygen content of blood due to anemia, and 3) a low arterio-venous oxygen saturation difference which is very surprising in anemic patients. The normal oxygen consumption rate was thus insured by a 70% increase of the cardiac output at rest. A particular abnormality found in SS patients was the high Po2 in mixed venous blood. The decreased affinity of blood for oxygen resulting from the polymerization of HbS in the erythrocytes led to an almost normal venous blood unsaturation and thus a decreased release of oxygen from this anemic blood. These results indicate that peripheral blood flow was permanently increased in SS patients. This may be in part at the origin of the arterial hypoxemia induced by an increased pulmonary blood shunting. Sickle cell anemia is more severe than other anemias of comparable intensity as, due to the sickling process, these patients appear to be at the upper limit of physiological compensatory mechanisms usually encountered in chronic anemia.

Adolescent↗

PubMed1980

[Value of the measurement of gases in the diagnosis of pleural effusion (author's transl)].

Determination of pH and measurement of pCO2 and pO2 have been systematically included in the study of 183 patients with pleural effusion. According to selective etiologic criteria the effusions were divided into four categories: those of cardiac origin (42), non-specific infectious (14), tuberculous (22) and neoplastic (20). A pH inferior to 6.30 seemed to be characteristic of non-tuberculous pleural effusion, and in these circumstances an associated pCO2 greater than 135 mm Hg and pO2 less than 21 mm Hg were noticed. Results in tuberculous and neoplastic cases were similar, pO2 being the only differential datum (pO2 less than 49 mm Hg and pO2 greater than 52 mm Hg, respectively). Overall results are compared to those obtained in the subgroup of pleural effusions of cardiac origin. Determination of pH, pO2 and pCO2 in pleural effusions may help to identified the etiology of this condition, specially when associated to analysis of other parameters of the aspirated fluid.

Carbon Dioxide↗

PubMed1983

Relationship of the biodisposition of the stereoisomers of nicotine in the central nervous system to their pharmacological actions.

The stereoisomers of nicotine were evaluated for their effectiveness in producing antinociception and altering spontaneous activity and Rotarod performance in rats. (-)-Nicotine was found to be 6, 15 and 30 times more active than its unnatural enantiomer, (+)-nicotine, in the spontaneous activity, Rotarod and antinociceptive tests, respectively. Biodispositional studies revealed that the time course (-)-[3H]nicotine closely paralleled the time course of effects on spontaneous activity and Rotarod performance but not antinociception, which suggested that multiple mechanisms were involved in the actions of nicotine. In addition, the distribution studies showed the brain and plasma levels of (-)-[3H]nicotine were higher than those of (+)-[3H] nicotine, which indicate that the pharmacological stereoselectivity of nicotine is less than originally determined. Finally, the greatest difference in the regional localization in brain of the stereoisomers was found in cerebral cortex, hippocampus and corpus striatum.

Analgesia↗

PubMed1981

Distinction of seventy-one cultured human tumor cell lines by polymorphic enzyme analysis.

A large collection of cultured human tumor cell lines was characterized for the phenotypes of 16 polymorphic enzyme loci: ACP1, ADA, AK1, ESD, FUCA, GLO1, GOT2, G6PD, ME2, PEPA, PEPB, PEPC, PEPD, PGD, PGM1, and PGM3 primarily to detect and monitor against cell line contamination. Among 100 highly characterized cell lines, 59 lines from different patients and 6 pairs of lines (each pair from the same patient's tumor) had unique phenotype combinations and were therefore presumed to be authentic, uncontaminated cell lines. Besides these 71 lines, the remaining 29 lines consisted of several small groups of two to three lines, each group having a different combination and being among the more frequent in the normal population. The 29 lines, therefore, were not suspected to be contaminants. Among unusual findings were the ME2 1 plus 2 phenotype determined for two bladder tumor lines, a G6PD A phenotype found in a line of Caucasian origin determined not to be a HeLa contaminant, and asymmetrical heterozygous phenotypes in several lines. Except for kidney tumor lines, there was no correlation of adenosine deaminase tissue isoenzymes between tumor lines and normal tissues of origin. For several enzymes significant deviations were found in proportions of the phenotypes observed in Caucasian cell lines from expected proportions on the basis of normal population data, indicating possible natural selection among these lines in tissue culture or among the patients of origin.

Cell Line↗

PubMed1995

[Is there an end to adolescence?--Observations from the ethnopsychoanalytic viewpoint].

Being an adult today does not mean anymore to have secure knowledge and routine at one's disposal, but rather being able to endure anxiety and uncertainty in culture. In the course of the process of civilization youth has more and more become the model and embodiment of a dynamic, ever-changing culture. As a consequence of abolishing initiation rituals, which originally determined the transition to adulthood, adolescents today must develop their own strategies in order to relate chaos and order to each other. The antagonism between family and culture plays a central role here: The individual must be able to personify two aggregate states as it were, that is being firm in the family and being fluid in culture. Today adolescence only ends inside the family when the individual takes on a parent role, but in the cultural area we should remain adolescents all of our lives, in order to muster the creativity necessary for a changing culture.

Adaptation, Psychological↗

PubMed1994

Comparative evaluation of body composition methods and predictions, and calculation of density and hydration fraction of fat-free mass, in obese women.

The objective of this study was to apply a three-component model of body composition to a group of obese women in order to (a) establish the relative value of a number of readily available prediction equations by comparison of the extent of agreement between these predictions and body composition estimated by the model and other reference methods and (b) evaluate density and hydration of fat-free mass. Estimation of body composition was carried out by reference methods and prediction equations and the usefulness of these prediction equations for application specifically to obese women was evaluated. The subjects were 15 obese, otherwise healthy, Caucasian women (body mass index > 30kg/m2 and body fat > 40% of body weight, as originally determined using densitometry). Body composition was estimated using three established reference methods (deuterium dilution which primarily measures total body water, densitometry for body fat and fat-free mass and total body potassium) and the three component model constructed from deuterium dilution and densitometry. Density and hydration fraction of the fat-free mass were calculated from appropriate values obtained as integral parts of the three-component model. In addition, body composition was predicted from various prediction equations incorporating weight and height (some of which include a factor for age), from a number of prediction equations utilizing different terms involving the same whole-body bio-electrical impedance measurement and from measurements of skinfold thickness and near infrared interactance. The extent of agreement between methods was assessed using bias and 95% limits of agreement. Mean density of fat-free mass was found to be 1.104 kg/l (s.d. 0.006kg/l) with a range of 1.093 to 1.117 kg/l, and mean hydration fraction was 0.712 (s.d. 0.016) with a range of hydration from 68.2% to 75.1% (all values were calculated from the three-component model). In general, the reference methods (densitometry, deuterium dilution, the three-component model and total body potassium) demonstrated better agreement with each other than with the prediction methods or equations. In these obese women, skinfold thickness measurements are apparently less reliable (large bias and 95% limits of agreement) than in the lean subjects of a variety of other studies. A majority of interpretations of weight and height measurements and predictions incorporating impedance/resistance measurements are apparently not applicable to this group of obese women, due to large values for both bias and 95% limits of agreement.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1994

Deoxyribonucleotides are maintained at normal levels in a yeast thioredoxin mutant defective in DNA synthesis.

Deletion of both thioredoxin genes TRX1 and TRX2 of Saccharomyces cerevisiae reduces the rate of DNA replication. This observation, originally determined by flow cytometry, was confirmed by radiochemical labeling of synchronized cultures. Since thioredoxin is a hydrogen donor to ribonucleotide reductase, a priori the inhibition of DNA synthesis was predicted to be caused by a reduction in the deoxyribonucleotide pools. However, the levels of TTP, dCTP, dATP, and dGTP were either unchanged or slightly greater in the thioredoxin mutant (3.2, 0.91, 1.4, and 1.21 pmol/10(6) cells, respectively) versus the wild-type culture (2.5, 0.91, 1.0, and 0.68 pmol/10(6) cells, respectively). An impact on ribonucleotide reduction was seen by an increased accumulation of RNR1 and RNR2 transcripts in the thioredoxin mutant (4.3- and 6.8-fold, respectively). Increased RNR expression did not reflect a general response of the DNA replication machinery. POL1 (DNA polymerase I) and CDC8 (thymidylate kinase) transcription were unaltered, while histone H2B transcripts actually decreased by half. Two alternative models incorporating these results are discussed. One suggests that thioredoxin reduces a multiprotein complex channeling nucleotides to the replication apparatus. The second proposes that thioredoxin regulates the tempo of DNA replication directly by activating a component of the replication machinery.

DNA Replication↗

PubMedDate not supplied

[Segments initiating replication of the dihydrofolate reductase domain and the DNA fragment DARC146 interact with the same nuclear proteins].

Comparison analysis was made of the putative replication origin DARC146 and the origin determined in the DNFR domain of CHO cells. We failed to observe extensive homology between these two sequences. However, several short (8-10 bp) areas of homology were identified. Some of them are binding sites for nuclear proteins. As shown by GM and competition experiments, both origins contain high-affinity binding sites for the transcription-replication factor Oct-1 and for two unknown nuclear factors. The two unknown nuclear factors bound to TCTCTTA and CACTTAG nucleotides. The binding sites for these proteins are located at a short distance from each other. This fact suggests interaction between these polypeptides. Measurement of DNA-binding activity of Oct-1 during the cell cycle of proliferating hepatocyte demonstrated that the binding activity of Oct-1 protein increased before initiation of DNA synthesis. The results of this report suggest that Oct-1 and two other nuclear proteins participate in the regulation of mammalian DNA replication. The results published early indicated the presence of an unusual DNA structure (bent DNA) in both origins under study. We suggest that these common elements of the origins regulate their activation.

Animals↗

PubMed1993

Antigenic characterization of human isolates of cryptosporidia.

Isolates of cryptosporidia from immunodeficient patients and from immunocompetent children suffering from diarrhoea were sources for preparation of antigens. Altogether, antigens from 21 isolates were obtained, 19 from children and 2 from AIDS patients. With one exception, all children were under 4 years old and most of them were between 1 and 2 years old. The probable source of infection was found in 11 cases. In 8 cases, as well as in both AIDS patients, the source of infection was not determined. The same groups of persons and the control group of healthy blood donors were examined serologically using ELISA with the antigen of bovine origin and positive sera were used for following experiments. Soluble and membrane-enriched antigens from oocysts were compared using polyacrylamide gel electrophoresis and electroimmunotransfer blots developed by human immune sera. While no differences were recorded in soluble antigens, two of the membrane-enriched antigens were missing (15.5 and 33 kD bands). While all isolates with a pattern typical for Cryptosporidium parvum were infective for neonatal mice, both isolates with missing bands were not infective for newborn mice in repeated experiments. The first of them was infective for chickens and was originally determined to be Cryptosporidium baileyi (Ditrich et al. 1991). However, the antigenic pattern differs from pattern of this species. The second isolate was infective for guinea pigs and its species classification remains uncertain.

Adolescent↗

PubMed1994

Validating the TMJ scale in a national sample of 10,000 patients: demographic and epidemiologic characteristics.

The accuracy and reliability of the TMJ Scale were originally determined in cross-validation studies on large, research-based patient samples. It had been assumed that the demographic characteristics and test responses of these research-based samples would be representative of the clinical population in which the TMJ Scale would ultimately find use. The present study on more than 10,000 patients that were evaluated for temporomandibular disorders in clinical practice demonstrates that the test scores, demographic variables, and the patterns of symptom severity that characterize the original TMJ Scale research sample accurately represent the general temporomandibular disorder patient population in which the TMJ Scale is now being used. The results suggest a high degree of confidence in the clinical efficacy of this assessment tool. The overall symptom severity of temporomandibular disorders was found to be normally distributed in the patient population. Women with temporomandibular disorders report a higher level of severity of all physical and psychological symptoms than men. This may explain the high female-to-male ratio in patients seeking treatment. However, a higher percentage of male temporomandibular disorder patients has clinically significant psychological and stress-related problems than do women. The severity and prevalence of symptoms associated with joint dysfunction and range of motion limitation are lower in older age groups, and the overall symptom severity of temporomandibular disorders is not higher in older age groups. However, the severity and prevalence of symptoms associated with joint dysfunction are greater in groups in which temporomandibular disorders have existed for longer durations, although pain levels do not follow this trend. There is also an association between time duration of the temporomandibular disorder and the severity of psychological problems and chronicity. Patients with chronic problems are symptomatically more impaired than those with acute problems.

Acute Disease↗