PubMed Health⌕ Search

Biomedical subjects

A E Kertesz

Publications and source records attributed to A E Kertesz.

At least 19 recordsLinked to original sources
PubMed1995

Screening blood donors for hereditary hemochromatosis: decision analysis model based on a 30-year database.

BACKGROUND & AIMS: The high prevalence, morbidity, premature death, and benefit of early diagnosis and treatment make hemochromatosis a prime target for screening in the white population. Decision analysis techniques were used to compare the outcome, utility, and incremental cost savings of a plan to screen voluntary blood donors for hemochromatosis. METHODS: The screening strategy includes sequential testing of serum unsaturated iron-binding capacity, serum transferrin saturation, serum ferritin, and either hepatic iron index or venesections to measure exchangeable body iron. Estimates of prevalence, asymptomatic intervals, probabilities of life-threatening clinical complications, symptom-specific life expectancy, and sensitivity and specificity of screening tests are based on our database of 170 hemochromatosis homozygotes and the published literature. RESULTS: The screening strategy led to an incremental increase in utility of 0.84 quality-adjusted life days with an incremental cost savings of $3.19 per blood donor screened. When the potential of identifying asymptomatic homozygous siblings was included, these values increased to 1.18 quality-adjusted life days and $12.57 per person screened. Screening remained a dominant strategy given a prevalence of hemochromatosis of > 0.0026 or an initial screening test cost of < $8. CONCLUSIONS: Screening blood donors for hemochromatosis has the potential to improve overall societal health status and decrease third-party payer health care costs over the long-term.

Adolescent↗
PubMed1995

Screening for hemochromatosis in children of homozygotes: prevalence and cost-effectiveness.

Although hereditary hemochromatosis is an autosomal recessive disease, most homozygotes are concerned with the genetic implications for their children. The optimal age for testing children and the cost implications of screening their children have not been clearly established. A clinical database consisting of 255 children from families with at least one homozygote is used to assess the prevalence of homozygotes among children of homozygous parents and to review the biochemical abnormalities and life-threatening symptoms in these young adults. Decision analysis is used to estimate the cost and utility of screening children of a homozygous parent. Eleven homozygotes were discovered among children of homozygotes. Only one male had a life-threatening event, cirrhosis. Decision analysis estimated cost saving of $12 per child screened ($ net present value) and a saving of 10 quality-adjusted days per child screened at age 10 years compared with not screening. If screening began at age 20 years, there is a cost saving of $65 per child screened. Sensitivity analysis showed that the major factors influencing cost savings were the cost of venesections, sensitivity and specificity of the screening tests, and prevalence of disease. Because the prevalence of hemochromatosis is higher in children of homozygotes than in the general population, screening with transferrin saturation and ferritin as early as age 10 years is recommended. Savings are augmented if the cost per venesection is eliminated by allowing hemochromatosis patients to become voluntary blood donors.

Adolescent↗
PubMed1993

Temporal and spatial aspects of sensory interactions during human fusional response.

Temporal and spatial aspects of sensory interactions during human fusional response were investigated using band-limited, 10th-derivative-of-Gaussian patterns confined to separate regions of the visual field. Experiments were performed to investigate the time course of sensory interactions using the horizontal sensory fusional amplitude (SFA) and the sensory fusional range (SFR) as measures of the interaction. The nature of sensory interactions across the spatial domain has been found to be a function of stimulus duration and time course. These interactions included both enhancements and reductions of SFAs as well as reductions and shifts in SFRs. Two functional components of sensory fusional interactions have become apparent. A fast component is manifested through a global reduction of SFAs while a slower component exhibits both enhancement and reduction of SFAs. The fast and slow components exhibit spatial summation; however, temporal summation within a local region of the visual field is not observed.

Adult↗
PubMed1993

Rate of iron reaccumulation following iron depletion in hereditary hemochromatosis. Implications for venesection therapy.

Although venesection therapy is well established for the initial depletion of iron stores in hereditary hemochromatosis, the frequency of subsequent therapy has not been clearly defined. In this study, 21 homozygotes (16 male, five female; mean age of 58, with a range of 26 to 77 years) who had completed initial venesection therapy were followed without further venesections for a mean of 4.0 years (range of 1 to 10.4 years) with iron reaccumulation assessed by annual serum ferritin concentration. Over the follow-up period, the mean rise in serum ferritin was 99 (micrograms/l)/year (range of 1.2 to 241 micrograms/l). The mean interval for the ferritin to become elevated above the normal range in 10 patients was 3.8 years. Eleven of 21 patients required no further venesection therapy over the follow-up interval. There was no significant correlation between the annual rate of ferritin increase and the age or amount of iron removed by prior venesections. These data demonstrate that monitoring body iron stores annually and the selective use of venesections if iron stores reaccumulate is a safe alternative to lifelong venesections every 2-4 months. Many homozygotes will not require reinitiation of venesection therapy for > 4 years. Annual monitoring of body iron stores with reinstitution of weekly venesection when the serum ferritin exceeds the upper limit of normal was a safe alternative to long-term maintenance venesection.

Adult↗
PubMed1992

Human leukocyte antigen typing of siblings in hereditary hemochromatosis: a cost approach.

To assess the clinical value of human leukocyte antigen typing in the diagnosis and management of hereditary hemochromatosis, 105 siblings of 35 proband cases of hemochromatosis were retrospectively analyzed to study whether the exclusion of human leukocyte antigen typing would have adversely affected management. All siblings and probands had already been tested for human leukocyte antigen-A and human leukocyte antigen-B typing, serum ferritin and transferrin saturation. The median age of siblings was 55 yr (range = 11 to 82). Siblings were categorized according to putative genotype (homozygote, heterozygote and normal) using human leukocyte antigen typing. Phenotypic expression of hemochromatosis was considered to be iron overload as indicated by an elevated ferritin (male = greater than 350 micrograms/L, female = greater than 200 micrograms/L) and/or transferrin saturation (greater than 55%). Six of 37 homozygotes had a normal ferritin and transferrin saturation, with five of these patients under 32 yr old. No putative heterozygotes with both an abnormal ferritin and transferrin saturation were seen, although 12 of 48 (25%) heterozygotes had either an elevated ferritin or transferrin saturation. Twenty of 20 normal siblings had a normal ferritin and transferrin saturation. To assess the cost of screening with and without human leukocyte antigen typing, a cost model simulation was used that compared the costs of both methods in a hypothetical family (proband, homozygote, heterozygote and normal sibling).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Long-term survival analysis in hereditary hemochromatosis.

This study investigated the long-term survival rates of 85 patients with hereditary hemochromatosis. Eighty-five patients with documented hereditary hemochromatosis diagnosed between 1958 and 1989 and followed up at the University Hospital (University of Western Ontario) medical center were retrospectively reviewed for this analysis. The current status of the patient was assessed by interview or written questionnaire completed by the patient or the family physician. Estimates of differences in survival rates were obtained using Kaplan-Meier life-table and Cox regression analysis. Liver histology, clinical features of the disease, and number of venesections were analyzed to determine their relationship to survival. In the course of a mean follow-up interval of 8.1 +/- 6.8 years (range, 0-31 years), there were 17 deaths among the 85 hemochromatosis patients. Patients with cirrhosis at the time of diagnosis were 5.5 times more likely to die than noncirrhotic patients. Patients who were noncirrhotic at the time of diagnosis had an estimated survival that was not significantly different from age- and sex-matched members of the normal population. Diabetes did not increase the risk of death after data were controlled for the presence of cirrhosis. Early diagnosis and treatment of hemochromatosis in the precirrhotic stage can lead to long-term survival similar to that in the general population. The presence of cirrhosis significantly increases mortality and is the major clinical factor affecting survival.

Aged↗
PubMed1991

Sensory interactions during human fusional response.

The nature of sensory interactions during human fusional response was investigated using band-limited, 10th-derivative-of-Gaussian patterns. Experiments were performed to investigate the effects of spatial separation, disparity magnitude, and stimulus spatial frequency on horizontal sensory fusional amplitudes (SFA). When the disparities in the inducing and probe regions were in the same direction the SFA for the probe increased; when the disparities were in opposite directions the SFA was reduced. Increases and decreases in the SFA for the probe caused by the inducing stimulus were designated enhancement and inhibition respectively. Both enhancement and inhibition increased with increasing inducing disparity. They were evident over a range of spatial frequencies from 0.75 to 3.0 c/deg and among retinal regions separated by as much as 1.5 deg arc. The SFA for the probe was not inhibited when the peak spatial frequency of the inducing stimulus was 2 octaves higher than that of the probe. The observed changes in SFA were found to be due to shifts in location rather than changes in the extent of the fusional range for the probe.

Convergence, Ocular↗
PubMed1991

Clinical presentation of hemochromatosis: a changing scene.

PURPOSE: To investigate the changing modes of clinical presentation and diagnosis in 93 patients with familial hemochromatosis and to compare the results with other reports from 1935 to the present. PATIENTS AND METHODS: The presenting features and the frequency of signs and symptoms were analyzed in 93 homozygotes from 56 families. RESULTS: Hemochromatosis was detected by chance in 40% of the 56 probands. Abdominal pain (16%), joint pains (11%), and weakness (9%) were prominent features that brought the patient to the physician. Although 38% of the male patients had loss of libido and impotence, these were not identified as presenting features. Features of liver disease (84%), arthritis (11%), and diabetes (2%) led the physician to the diagnosis. Impotence and testicular atrophy were notable, by their absence, in alerting physicians to the presence of hemochromatosis. Screening of family members led to the detection of 37 homozygotes, of whom 46% were asymptomatic. Among this group, arthropathy and gonadal failure were the most common symptoms. The classic triad of hepatomegaly, diabetes, and pigmentation was present in only 8% of patients. Clinical features were rare in patients with less than 5 g of exchangeable body iron and invariably present in those with more than 16 g. CONCLUSION: The presenting clinical features of hemochromatosis have changed since the original description of the disease in 1935. Family studies have led to the earlier discovery of more homozygous women and earlier detection with less iron loading and, as a result, fewer signs and symptoms.

Adolescent↗
PubMed1988

The nature of sensory compensation during fusional response.

Simultaneous objective (based on binocular eye movement recording) and subjective (nonius line displacement) measurements of horizontal and vertical fusional response were carried out in order to examine the nature of sensory fusional compensation. It was found that the presence of sensory compensation in one retinal region affects the sensory representations of neighboring regions. Unlike motor compensation, however, sensory compensation affects fusible and nonfusible contours differently. The implication of these results is examined for the reliability of subjective determinants of binocular status.

Adult↗
PubMed1987

Comparison of simultaneously obtained objective and subjective measurements of fixation disparity.

Simultaneous objective (based on binocular eye movement record) and subjective (nonius-line displacement) measurements of horizontal and vertical fixation disparity were carried out in order to evaluate the reliability of the nonius-line method of measuring ocular deviation. Significant differences were found between the subjective and objective measurements. These differences indicate that the nonius-line method is unreliable for the measurement of ocular deviation or fusional status.

Eye Movements↗
PubMed1986

Wide-field fusional stimulation in strabismus.

The effectiveness of wide-field fusional stimulation was evaluated on 57 strabismics and 29 patients with convergence insufficiency. The strabismics had fusion, normal retinal correspondence (even if it coexisted with anomalous retinal correspondence), a deviation not exceeding 30 delta, and visual acuity of 6/7.5 or better. The strabismics included intermittent exotropes, surgically overcorrected intermittent exotropes, and accomodative esotropes. Of these strabismic patients, 42 responded to therapy in which tropias were converted to phorias or the frequency of the manifest deviation was significantly reduced, fusional amplitudes were significantly enlarged, and in many cases, stereoacuity improved as well. In 16 cases, surgery that was recommended before treatment is no longer being considered. Of the patients with convergence insufficiency, 23 responded to therapy which resulted in the enlargement of fusional amplitudes and the alleviation of symptoms. Follow-up visits (for up to 5 years) confirm that the improvement persists, which indicates the utility and effectiveness of this technique.

Accommodation, Ocular↗
PubMed1985

Effect of stimulus parameters on fusional and stereoscopic performance.

The effect of stimulus size and complexity on the horizontal divergent diplopia threshold, stereoscopic range, reappearance of stereopsis, and re-fusion point was examined. It was found that the addition of random-dot (RD) backgrounds significantly increased both the diplopia threshold and re-fusion point, whereas the further addition of multiple depth planes did not. Stereopsis and diplopia were found to coexist in RD stereograms both when the disparity increased past the diplopia threshold and when it was decreasing toward the re-fusion point. This suggests that monocularly distinguishable contours must be added to RD stereograms to render them suitable for the measurement of fusional amplitudes.

Adult↗
PubMed1985

Horizontal fusional responses to stimuli containing artificial scotomas.

Horizontal fusional responses were studied with stimuli containing binocular or monocular, artificial, stabilized, scotomas. Binocular scotomas of 5-deg, 10-deg, and 15-deg diameters were utilized. The fusional responses to scotomatic stimuli were compared with full-field stimulus responses. All responses contained significant motor and nonmotor (sensory) components. Overall motor compensation to stimuli with 10-deg and 15-deg scotomas was reduced, while the overall motor compensation to stimuli with 5-deg scotomas was not. With full-field stimuli and with stimuli containing binocular scotomas, the changes in the two eyes' lines of sight were often asymmetric in response to symmetric disparity changes. This response asymmetry was exacerbated by the presence of monocular scotomas. Fixation was less steady with stimuli containing 10-deg or 15-deg binocular scotomas than it was in response to full-field stimulation. The fusional responses to annular stimuli were similar to those elicited by scotomatic stimuli.

Convergence, Ocular↗
PubMed1985

Fusional responses of strabismics to foveal and extrafoveal stimulation.

Horizontal fusional responses of 11 strabismics, with normal or anomalous retinal correspondence, were studied. These included four small-angle esotropes with amblyopia, one intermittent esotrope (overcorrected intermittent exotrope), two intermittent exotropes (preoperative esotropes), one accommodative esotrope, and three microtropes with amblyopia. Fusional stimuli (with a constant accommodative demand) ranging from very small, central stimuli to those that cover the central, the peripheral, and both the central and the peripheral visual fields were used. All 11 strabismics produced fusional vergence responses. Many of the fusional responses included large nonmotor components. Small central stimuli were not effective in producing fusional vergence, whereas stimuli that covered the visual periphery produced fusional responses that were similar to those by subjects with normal stereoscopic vision.

Adolescent↗
PubMed1983

The extent of Panum's area and the human cortical magnification factor.

The horizontal extent of Panum's fusional area was measured by means of a single-vertical-line stimulus placed at thirty-two locations throughout the peripheral visual field. These results were transformed by using known values of the human cortical magnification factor (CMF), and the hypothesis that variations in the magnitude of Panum's area may be accounted for by variations in the CMF was tested. It was found that the increase in Panum's area with increasing stimulus eccentricity correlates well with the CMF, but that variations in the extent of Panum's area as a function of angular position around the line of sight do not correspond well with the CMF.

Adult↗