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At least 1,603 records · Page 89Linked to original sources
PubMed2000

Axonal regeneration of retinal ganglion cells depending on the distance of axotomy in adult hamsters.

PURPOSE: To examine the relationship between the distance of axotomy and axonal regeneration of injured retinal ganglion cells (RGCs) systematically and the effect of a predegenerated (pretransected or precrushed) peripheral nerve (PN) graft on axonal regeneration of RGCs axotomized at a definite distance (0.5 mm from the optic disc) in comparison with a normal PN graft. METHODS: The optic nerve (ON) was transected intraorbitally at 0.5, 1, 1.5, 2, or 3 mm or intracranially at 6 to 8 mm from the optic disc, and a PN graft was transplanted onto the ocular ON stump in adult hamsters. Four weeks after grafting, the number of RGCs regenerating their injured axons into the PN graft was investigated in all animals. RESULTS: The number of regenerating RGCs decreased significantly when the distance of axotomy increased from 0.5 to 7 mm. A precrushed PN graft was shown to enhance more injured RGCs to regenerate axons than a normal or pretransected PN graft. CONCLUSIONS: The distance of axotomy on the ON of adult hamsters is critical in determining the number of regenerating RGCs. Thus, experimental strategies to repair the damaged ON by PN transplantation is to attach a precrushed PN graft as close to the optic disc as possible to obtain optimal axonal regeneration of the axotomized RGCs.

Animals↗
PubMed2000

Using semantic distance for the efficient coding of medical concepts.

OBJECTIVE: To use the notion of semantic distance to find the nearest neighbors of a medical concept in a controlled vocabulary. MATERIAL AND METHOD: 392 concepts from the cardiovascular chapter of the ICD-10 were projected on the axes of SNOMED III. Distances were measured on each axis and the resulting distance was found using a Lp norm. RESULTS: The distance between a set of ischemic diseases and a set of non-ischemic diseases was significant (p < 0.0001). Our method was validated by finding the k nearest neighbors of ten different diagnoses from the ICD-10 cardiovascular chapter. DISCUSSION: The availability of SNOMED-RT should improve our method. Several more steps are necessary to provide an ideal coding tool.

Cardiovascular Diseases↗
PubMed2001

The effects of sublingual glyceryl trinitrate on walking distance in patients with intermittent claudication. A randomised, doubled-blind, placebo-controlled, cross-over study.

BACKGROUND: Intermittent claudication (IC) is a common problem in older age. New work shows that the administration of glyceryl trinitrate (GTN) can reduce the fall in ankle brachial pressure index (ABPI) after exercise and can increase maximum walking distance by 19% on treadmill exercise. The aim of this study was to further define the clinical benefits of GTN in patients with PVD. METHODS: The study is of a randomised, double-blind, placebo-controlled cross-over design. We studied 29 patients with intermittent claudication where the median age was 67.5 years (45-84). This included 20 males and nine females, and six of these patients were diabetics. To be selected, the patients had to have a history of IC with a resting ABPI of 1.0 or less, that fell by more than 0.1 on exercise. Patients were walked for 15 min on flat ground following GTN spray or placebo and total distances walked were measured. This was then followed by the crossover component of the trial. RESULTS: Median walking distance with placebo was 825 m (100-1300 m) and with GTN was 900 m (240-1400 m). This is an increase of 9% (p = 0.02, using the Wilcoxon matched pairs signed ranks test). CONCLUSION: This study shows a statistically significant improvement in walking distance with GTN in patients with IC.

Administration, Sublingual↗
PubMed2002

Minimal distances between temporal bone structures and their mutual correlations.

BACKGROUND: The minimal distances between basic temporal bone structures limit the operating field in ear surgery. The aim of the present study was to perform measurements on the minimal distances between key structures of the temporal bone and to investigate possible correlations between given structures. MATERIAL/METHODS: The author removed 100 temporal bones from subjects of both sexes, across a range of age groups and from both sides of the body. Minimal distances were measured between the following structures: the lateral semicircular canal (SC), the tympanic ring (TR), the hard meninges of the middle cranial fossa (HM), the facial nerve (FN), the upper bulb of the internal jugular vein (JB) and the internal carotid artery (CA), collected in the appropriate pairs. The samples were measured using an operating microscope equipped with a graduated eyepiece. RESULTS: The results are presented in various categories according to age, sex, and side of the body. Five pairs of distances were found to be significantly shorter in younger children (group I) than in older children and adults (group II). CONCLUSIONS: Ear surgery in younger children demands much more care than in older children and adults, especially regarding situations when the jugular bulb is in the operating field.

Adolescent↗
PubMedDate not supplied

Treatment of intermittent claudication with pentoxifylline: a 12-month, randomized trial--walking distance and microcirculation.

The efficacy, safety and cost of pentoxifylline (PXF) in severe intermittent claudication was studied comparing PXF and placebo in a 12-month study. A treadmill test and microcirculatory evaluation with laser Doppler flowmetry were performed at inclusion and at the end of 6 and 12 months. A physical training plan (based on walking) and reduction in risk factor levels plan was used in both groups. Of the 120 included patients, 101 completed the study: 56 in the PXF group and 45 in the placebo group. There were 19 dropouts (due to low compliance). The two groups were comparable for age, sex distribution, walking distance, and the presence of risk factors and smoking. Intention-to-treat analysis indicated a 268% increase in walking distance in the PXF group (vs 198% in the placebo group; p<0.05) at 6 months and an increase of 404% (vs 280% in the placebo group; p<0.02) at 12 months. The absolute and percent increase in pain-free walking distance (PFWD) was greater in the PXF group (p<0.05). Treatment was well tolerated. No serious drug-related side effects were observed. Microcirculatory evaluation indicated an increase in flux (p < 0.05) in the PXF group (not significant in the placebo group); the after-exercise flux (AEF) was increased (p<0.05) in both groups at 6 months but the increase in AEF was greater in the PXF group at 12 month. In conclusion, between-group analysis favors PXF considering walking distance and microcirculatory parameters. Results indicate good efficacy and tolerability.

Aged↗
PubMed2002

[A study on cases of good apparent accommodation using an all-distance visual acuity chart and corneal shape analysis].

PURPOSE: As a part of an attempt to elucidate the mechanism of apparent accommodation, an evaluation was made of patients with good apparent accommodation using an all-distance visual acuity chart and corneal shape analysis. MATERIALS AND METHODS: The study was performed on 6 patients (7 eyes) in a good apparent accommodation group and 13 patients (15 eyes) in a poor apparent accommodation group. These were selected from patients who had undergone normal small-incision ultrasonic phacoemulsification and posterior chamber type single focus intraocular lens implantation. In these patients, all-distance visual acuity was measured using an AS-15(Kowa Co., Ltd.), and corneal shape analysis was performed using Orbscan (Orbtek Inc.). RESULTS: In all-distance visual acuity, gentle decline from far to near was noted in the poor apparent accommodation group, and the degree of decline was lower in the good apparent accommodation group. Also, a two-peak pattern, showing decline at first and then an increase, was observed in some of the cases. In corneal shape analysis, there was no specific pattern in the good apparent accommodation group. However, the difference between maximum refractive power and minimum refractive power of cornea in the ranges of 3, 5, and 7 mm in total optical power (TOP) was significantly higher in the good apparent accommodation group compared with the poor apparent accommodation group (TOP 3 mm: p = 0.0233, TOP 5 mm: p = 0.0306, TOP 7 mm: p = 0.0035). CONCLUSION: In the present study, there were three patterns in all-distance visual acuity in the good apparent accommodation group, showing a two-peak pattern, a flat pattern, and a gentle decline, and the pattern of gentle decline was observed more often than the other patterns. The results of the study also suggest that the gradient of corneal refractive power may be related to apparent accommodation.

Accommodation, Ocular↗
PubMed2002

Estimation of inbreeding, kinship and genetic distances from surnames--coastal population of middle Dalmatia, Croatia.

This work was dedicated to the investigation of the population structure of the middle Dalmatia settlements: Jesenice, Mimice, Zivogosće and Zaostrog by surname distribution study and applying the isonymous method. The surnames of males and females in marital pairs were analyzed as well as of their first and second-generation ancestors on the sample of a total of 3,024 examinees. The analyses of surnames pointed to the rates of inbreeding, kinship and genetic distances of the populations. Although the values of the inbreeding coefficient are high in all the four settlements, the inbreeding coefficient is exceptionally high in Mimice. A total kinship coefficient for the four settlements speaks also in favor of the high rate of kinship in the examined settlements, i.e. of the high rate of the reproductive isolation of the whole region during the analyzed period. The reasons for such high coefficients are natural features of the examined region (the mountains of Mosor, Biokovo and Rilić), poor traffic connection of this region in the past, the patrilineal mode of inheritance and the demographic specifics of the population. The matrix of genetic distances between examined settlement pairs reveals that Mimice, a settlement with the highest share of isonymous marriages, shows the greatest distances in comparison to the other settlements. On the other hand, Jesenice, Zivogosće and Zaostrog are characterized by small genetic distances, which is the fact that speaks in favor of their genetic homogenization and "openness" toward interpopulational migrations, i.e. the gene flow.

Consanguinity↗
PubMedDate not supplied

Influence of curing tip distance on resin composite Knoop hardness number, using three different light curing units.

This in vitro study evaluated the influence of curing tip distance on the Knoop Hardness Number (KHN) of a resin composite when using three different light curing units: (1) a halogen light (XL 1500 curing unit-3M), (2) a "softstart-polymerization" (Elipar Trilight curing in an exponential mode-ESPE) and (3) a PAC (Apolo 95E curing unit-DMD). The resin composite, Filtek Z250 (3M), was cured by these curing units at three light-tip distances from the resin composite: 0 mm, 6 mm and 12 mm. The resin composite specimens were flattened to their middle portion and submitted to 18 KHN measurements perspecimen. The results showed that for the Elipar Trilight unit, the hardness of the resin composite decreased as the light tip distance increased. The XL 1500 unit presented a significant decrease in hardness as the depth of cure of the resin composite increased. Apolo 95E caused a decrease in the resin composite hardness values when the depth of cure and light tip distance increased.

Analysis of Variance↗
PubMed2003

The symptomatic patient with normal phorias at distance and near: what tests detect a binocular vision problem?

PURPOSE: Patients often manifest symptoms that appear to be related to binocular distress. Many of these patients have normal heterophoria at distance and near, making the etiology of such symptoms perplexing. We performed a visual examination of patients having normal heterophoria at distance and near in order to investigate which visual analysis tests differentiate symptomatic from asymptomatic patients. METHODS: Eighty subjects (30 symptomatic, 50 asymptomatic) with ages between 18 to 35 years of either sex and any race were pooled based on vision-symptom level determined by a 9-question standardized visual-symptoms questionnaire scored using a 100-point scale (asymptomatic: score > or = 85; symptomatic: score < or = 75). Inclusion/exclusion criteria included vision correctable to 6/6 (20/20) Snellen acuity or better in each eye, normal phorias, no latent cyclovertical heterophoria, and normal ocular health. RESULTS: Of the 30 symptomatic patients, 18 had reduced vergence facility response using 3 pd base-in/12 pd base-out loose prism at distance (n = 10; t-score = 2.41, p < 0.02, d = 76) and near (n = 15; t-score = 3.32, p < 0.01, df = 78) with a significant difference beyond the 0.02 level. No other test including measurement of accommodation, showed a significant between-group difference. However, three patients with normal vergence facility (distance and near) showed a reduced binocular accommodative facility response (+/-2.00 D at 40 cm). CONCLUSION: Given a patent with asthenopia, normal phorias, and visual acuity, a differential diagnosis may be made based primarily on using vergence facility and accommodative facility testing. From a clinical standpoint, the results expedite diagnosis of binocular vision abnormalities and direct treatment.

Accommodation, Ocular↗
PubMed2003

The effect of distance from light source on light intensity from curing lights.

PURPOSE: To investigate how light intensity changes as the distance increases from the tip of the light guide. MATERIALS AND METHODS: Ten different curing light/light guide combinations were used. Light intensity was measured at 0, 3, 6, and 10 mm from the tip of the light guide with a radiometer. Measurements were repeated in five separate trials and the mean light intensity +/- standard deviation was calculated. The fiber density was measured at the entrance and exit of all ten light guides and the light dispersion patterns were recorded. RESULTS: Light intensity decreased as distance increased for all lights tested; however, the rate and extent of this decrease was not similar for all lights (p < 0.0001). Turbo light guides exhibited a more rapid decrease in intensity as the distance increased than standard light guides. At 10 mm, all the turbo light guides had lost over 80% of their intensity recorded at 0 mm. CONCLUSION: 1. The rate and extent of the decrease in intensity is not similar among curing lights (p < 0.0001). 2. It is not possible to predict light intensity at 10 mm from measurements made at 0 mm. 3. Curing light manufacturers should state intensity over clinically relevant distances (0 to 10 mm).

Analysis of Variance↗
PubMed2004

[Mucus plugs in the ventral bronchi travel less distance than those in the dorsal bronchi: HRCT observation in third-order or smaller bronchi].

PURPOSE: To examine on HRCT whether there is a difference in the respiratory moving distance of bronchial mucus plugs between ventral and dorsal bronchi. MATERIALS AND METHODS: We examined 36 ventral and dorsal bronchi of the same order in 18 patients with mucoid impaction depicted on HRCT. CT data were obtained by multidetector-row CT. HRCT images of 0.5 mm thickness and 0.3 mm interval were reconstructed. We selected one slice including a mucus plug take-off from each bronchus. When they were not included in a slice, we reconstructed a 1-3 mm slab-thickness MIP image. In these images we measured the distance between the take-off of each bronchus and the hilar margin of the mucus in same-order ventral and dorsal bronchi. We also measured CT attenuation in the ROI of the subpleural region excluding vessels in the same slice. When the differences in distances (delta D) and CT attenuations (delta C) between inspiration and expiration were obtained, we analyzed the correlation between delta D and delta C in ventral and dorsal bronchi, respectively. We also compared delta D between ventral and dorsal bronchi. RESULTS: Mean delta C was 36.26 +/- 2.78 HU. Ventral delta D was 6.46 +/- 3.75 mm, and dorsal delta D was 2.57 +/- 1.59 mm. The correlation between delta C and dorsal delta D was significant (r = -0.78, p < 0.005), whereas that between delta C and ventral delta D was not (r = 0.23, p = 0.64). The ventral delta D was significantly smaller than the dorsal (p < 0.05). CONCLUSION: Between inspiration and expiration in the supine position, mucus plugs in the ventral bronchi travel less distance than those in the dorsal bronchi.

Adult↗
PubMed2006

Confirmed: there is no correlation between the insertional distance between the nasal limbus and the insertion of the medial rectus muscle--and the size of the strabismus angle in infantile esotropia.

INTRODUCTION: Historical systems of measuring the amount of surgical recession of the medial rectus muscles appropriate to be performed for a given size of angle of infantile esotropia, based upon relative recession measurement from the limbus might have proven to be better than relative recession measurement from the insertion--if a positive correlation were found between the size of the angle of the esodeviation and the distance between the insertion of the medial rectus and the nasal limbus. A search of the scientific literature since 1966 as listed in PubMed (National Library of Medicine, formerly Index Medicus) did not reveal any additional confirmatory study of this type in PubMed. We therefore undertook to perform such a study. METHODS: Using standard strabismus calipers, at surgery for esotropia, intraoperative measurements were made of the insertional distance (in mm between the most nasal point of the clear cornea and, following standard surgical excision of the muscle from the globe, the anterior insertional ridge of the medial rectus muscle of the eye) in a series of 104 consecutive infantile esotropes operated by the author between 1987 and 1991. These data were then graphically plotted as the ordinate with the abscissa defined as the size of the angle of the esotropia measured with the prism alternate cover test the day prior to surgery. RESULTS: No correlation was found between the medial rectus muscle insertional distance and the size of the preoperative esodeviation in prism diopters, correlation coefficient r=0.14, p=0.078. DISCUSSION OF RESULTS: In this large series, the lack of a correlation has credibility as it fails to achieve conventional limits of a "statistical significance" of the difference. CONCLUSION: The lack of correlation between the size of the deviation and the insertional distance offers support for the widespread acceptance and use of the alternative, the dose-response curves based on the mm of recession measured from the anterior ridge of the medial rectus muscle insertion.

Esotropia↗
PubMed2006

On genetic information, diversity and distance.

OBJECTIVES: General information-theoretic concepts such as f-divergence, f-information and f-entropy are applied to the genetic models where genes are characterized by randomly distributed alleles. The paper thus presents an information-theoretic background for measuring genetic distances between populations, genetic information in various observations on individuals about their alleles and, finally, genetic diversities in various populations. METHODS: Genetic distances were derived as divergences between frequencies of alleles representing a gene in two different populations. Genetic information was derived as a measure of statistical association between the observations taken on individuals and the alleles of these individuals. Genetic diversities were derived from divergences and information. RESULTS: The concept of genetic f-information introduced in the paper seems to be new. We show that the measures of genetic distance and diversity used in the previous literature are special cases of the genetic f-divergence and f-diversity introduced in the paper and illustrated by examples. We also display intimate connections between the genetic f-information and the genetic f-divergence on one side and genetic f-diversity on the other side. The examples at the same time also illustrate practical computations and applications of the important concepts of quantitative genetics introduced in the paper. CONCLUSIONS: We discussed a general class of f- divergence measures that are suitable measures of genetic distance between populations characterized by concrete frequencies of alleles. We have shown that a wide class of genetic information, called f-information, can be obtained from f-divergences and that a wide class of measures of genetic diversity, called f-diversities, can be obtained from the f-divergences and f-information.

Databases, Genetic↗
PubMed2006

Does long-distance running cause osteoarthritis?

There is a dose-response relationship between physical activity and the reduced risk of some diseases (eg, cardiovascular disease, diabetes mellitus). At a certain "dose," however, the reduced risk of some diseases may be offset by an increased risk of injury and osteoarthritis. Osteoarthritis can be caused by trauma to, or overuse of, the joints. Sports injuries often occur as a result of dysfunctions in balance or the musculoskeletal system operating in nonneutral mechanics. It is unclear if long-distance running causes the knee and hip joints to deteriorate. The results of animal studies reveal a pattern of increased incidence of arthritis in these joints when there is a history of injury or use in atypical environments (eg, laboratory settings). Human studies show an increase in radiographic evidence of osteoarthritis in endurance sports athletes, but no related increase in symptoms reported. Although there are not currently enough data to give clear recommendations to long-distance runners, it appears that long-distance running does not increase the risk of osteoarthritis of the knees and hips for healthy people who have no other counterindications for this kind of physical activity. Long-distance running might even have a protective effect against joint degeneration. The authors recommend further study.

Age Factors↗
PubMed2006

The role of race, socioeconomic status, and distance traveled on the outcome of African-American patients with multiple myeloma.

The incidence and mortality of multiple myeloma (MM) in African-Americans is double that in whites. We questioned whether race, socioeconomic status, and distance traveled affect overall survival. In a retrospective review of the records of 292 patients with MM. We found that the median age was 60 years and 38 patients were African-Americans. The mean distance traveled was 67.7 miles. The median overall survival was similar in African-Americans and whites. Race, distance traveled and socioeconomic status were not independent prognostic factors for overall survival. In conclusion, socioeconomic status, distance traveled and race did not affect outcomes of MM patients treated at a specialized myeloma center.

Black or African American↗
PubMedDate not supplied

Variation in the mortality rate of turkeys during transport to the slaughterhouse with travel distance and month.

Failure to comply with animal welfare requirements during the transport of turkeys to the slaughterhouse increases stress in animals, which is manifested by increased mortality rate during transport. The numbers of turkeys that died during transport or soon after arrival may serve as an important parameter to indicate the level of animal welfare during transport of turkeys. The number of turkeys that died during transport to slaughterhouses in the Czech Republic in the period from 1997 to 2004 was investigated. The mortality rate found was 0.28% +/- 0.06% but varied with travel distance. The lowest mortality rate was found in case of travel distance below 50 km (0.18% +/- 0.08%) while long travel distances resulted in considerable increase in the mortality rates of turkeys (between 0.28% +/- 0.07 and 0.37% +/- 0.10%). The mortality rate of transported turkeys was also affected by the particular month of the year. Thus, the highest overall mortality rate occurred at long travel distances during winter months, i.e. in December (0.34% +/- 0.18%), January (0.32% +/- 0.06%), and February (0.36% +/- 0.07%). The comparison of individual years has shown a long-term trend towards a decrease in turkeys' mortality during transportation to slaughterhouses from 0.32% in 1998 to 0.20% in 2004. The decrease was statistically significant (Spearman's rank correlation coefficient r = -0.86, p < 0.01). This trend can be evaluated as positive.

Abattoirs↗
PubMed1991

[Study of the breed-forming process in sheep using multivariate methods of analysis of genetic and morphologic distances].

Comparison of biochemical genetic variation and morphological variation during formation of a new breed of sheep by means of multi-breed mating has been carried out. Genetic distances calculated by biochemical markers using various methods (by M. Nei, J.S. Rogers, I.I. Cavalli-Sforza and A.W.F. Edvards) have been discovered to significantly correlate with Manhattan and average taxonomic distances calculated on the basis of six morphological traits (r = 0.841-0.889, t = 2.98-2.99, P = 0.999). Nevertheless, it appeared that relationships between crossbred animals revealed with the help of methods for multidimensional analysis (principle component analysis and multidimensional scaling) on the basis of genetic distances matrix more precisely correspond to the real scheme and direction of breeding work than relationships described while using the given methods on the basis of morphological distances matrix. Greater correspondence of data on biochemical genetic variations of the animal groups studied to real processes of breeding, as compared with the data on morphological traits, is supposed to be connected with direct involvement of non-accounted phenotypic characters into the breeding work.

Animals↗
PubMed1991

Distance learning for rural medical officers in Kenya: the first pilot project.

Representatives from the Ministry of Health, the University of Nairobi and the Kenya Medical Association arranged a workshop in Nairobi in September, 1987 to ensure that policy makers, civil servants, academics and senior members of the medical profession would feel fully informed about the purpose and nature of distance learning. A further meeting was arranged for the supervisors and tutors who would be involved in the pilot project which was designed to validate the usefulness of distance learning materials prepared in London and to evaluate the organisational and educational aspects of the local system for distance learning. Ten rural medical officers, selected by the Ministry, met to be inducted at a briefing workshop in Mombasa. The medical officers were invited to study with three modules at their place of work during a period of six months and to complete a field project during the next six months. They were asked to keep a dairy, to use a notebook for critical comments on each module, and to complete two questionnaires. Their pre-test performance was compared with post-test performance. The results were analysed with a view to improving the modules and the local distance learning system.

Attitude of Health Personnel↗