Biomedical subjects

R Hiller

Publications and source records attributed to R Hiller.

At least 19 recordsLinked to original sources

PubMed2006

The performance of a component-based allergen-microarray in clinical practice.

BACKGROUND: Currently, the diagnosis of IgE-mediated allergy is based on allergen-specific history and diagnostic procedures using natural allergen extracts for in vivo and in vitro tests. OBJECTIVE: The aim of the study was to comparatively analyse a new component-based allergen-microarray and the 'quasi-standard' ImmunoCAP for their clinical relevance in patients with allergic rhinoconjunctivitis to five aeroallergens [house dust mite (HDM), cat dander, birch, grass and mugwort pollen] in a prospective, double-centre study. METHODS: We enrolled 120 subjects at the two study centres. Allergic patients were defined as having an allergen-specific history plus a concomitant positive skin-prick test (SPT) to natural allergen extracts and specific serum IgE was measured by both methods. Each allergen was analysed separately. RESULTS: The microarray performed equally well in receiver-operating characteristic curve (ROC) analyses when compared with the CAP in cat (23 allergic vs 97 non-allergic, ROC area under the curve microarray 0.950 vs CAP 0.894, P = 0.211), birch (31/89, 0.908 vs 0.878, P = 0.483) and grass pollen (47/73, 0.923 vs 0.915, P = 0.770). It was slightly less sensitive in HDM-allergic subjects (26 allergic vs 94 non-allergic, ROC area microarray 0.808 vs CAP 0.911, P = 0.053) and displayed a reduced sensitivity in the mugwort pollen-allergic patients (17/103, 0.723 vs 0.879, P = 0.032). CONCLUSIONS: Component-based testing and the whole-allergen CAP are equally relevant in the diagnosis of grass-, birch- and cat-allergic patients. Although slightly less sensitive, the microarray is sufficient for the diagnosis of HDM-allergic patients, but needs alternative and/or additional components for detecting mugwort allergy.

Adult↗

PubMed2003

Microarrayed recombinant allergens for diagnosis of allergy.

We suggest that the coapplication of recombinant allergens and microarray technology can lead to the development of new forms of multi-allergen tests which allow the determining and monitoring of complex sensitization profiles of allergic patients in single assays. The allergen extracts which have so far been used for diagnosis only allowed the determining of whether an allergic patient is sensitized against a particular allergen source, but the disease-eliciting allergens could not be identified. Through the application of recombinant DNA technology a rapidly growing panel of recombinant allergen molecules has become available which meanwhile comprises the epitope spectrum of most of the important allergen sources. We demonstrate that microarray technology can be used to establish multi-allergen tests consisting of microarrayed recombinant allergen molecules. Microarrayed recombinant allergens can be used to determine and monitor the profile of disease-eliciting allergens using single tests that require minute amounts of serum from allergic patients. The wealth of diagnostic information gained through microarray-based allergy testing will likely improve diagnosis, prevention and treatment of allergy.

Allergens↗

PubMed2003

Allergen microarray: comparison of microarray using recombinant allergens with conventional diagnostic methods to detect allergen-specific serum immunoglobulin E.

BACKGROUND: The availability of recombinant allergens and recent advances in biochip technology led to the development of a novel test system for the detection of allergen-specific IgE. OBJECTIVE: To test the performance of this allergen microarray in a serological analytical study. METHODS: Standard allergens contained in grass pollen (Phl p 1, Phl p 2, Phl p 5 and Phl p 6) and tree pollen (Bet v 1 and Bet v 2) were used as a model system. The detection of allergen-specific serum IgE using microarrays was compared with standard test systems: CAP/RAST and an in-house ELISA. In order to test the analytical sensitivity of the assays, geometric dilutions of a serum pool containing high levels of pollen-specific IgE from allergic individuals were tested in each system. To assess the analytical specificity, the sera of 51 patients with presumptive allergic symptoms were collected before diagnosis. Thereafter, the results for grass/tree-pollen-specific IgE were compared. RESULTS: The microarray has a good dynamic range similar to the CAP/RAST system. Microarray and ELISA showed comparable analytical sensitivity exceeding the CAP/RAST system. With respect to the analytical specificity, no significant cross-reactivity of the allergens was observed. For two of the allergens tested, weak positive signals were detected in the microarray test system, whereas they were not detectable by CAP/RAST. CONCLUSION: A good correlation of presently used methods to detect serum IgE and the novel microarray test system was observed. As a next step, a careful validation of this method for a multitude of allergens and a thorough clinical evaluation has to be provided. Microarray testing of allergen-specific IgE can be presumed to be the method of choice for a prospective component-resolved diagnosis of Type I allergy, and the basis for the design and monitoring of a patient-tailored specific immunotherapy in the future.

Allergens↗

PubMed2001

Detection of single base alterations in genomic DNA by solid phase polymerase chain reaction on oligonucleotide microarrays.

DNA microarray technology holds significant promise for human DNA diagnostics. A number of technical approaches directed at the parallel identification of mutations or single nucleotide polymorphisms make use of polymerase-based specificity, like minisequencing or allele-specific primer elongation. These techniques, however, require separate laborious sample amplification, preparation, and purification steps, making large-scale analyses time and cost consuming. Here, we address this challenge by applying an experimental setup using simultaneous solid and liquid phase PCR on polyethyleneimine-coated glass slides, a novel microarray support allowing on-chip amplification reactions with exquisite specificity. A gene-specific oligonucleotide tiling array contains covalently attached allele-specific primers which interrogate single nucleotide positions within a genomic region of interest. During a thermal cycling reaction amplification products remain covalently bound to the solid support and can be visualized and analyzed by the incorporation of fluorescent dyes. Using the described procedure we unequivocally defined the presence of point mutations in the human tumor suppressor gene p53 directly from a natural DNA source. This semi-multiplex solid phase amplification format allowed the rapid and correct identification of 20 nucleotide positions from minute amounts of human genomic DNA. Our results suggest that this approach might constitute a vital component of future integrated DNA chip devices used in gene analysis.

Base Composition↗

PubMed2001

Postmenopausal estrogen use, type of menopause, and lens opacities: the Framingham studies.

BACKGROUND: Previous studies of estrogen replacement therapy and lens opacities have not reported consistent findings. OBJECTIVE: To investigate whether postmenopausal estrogen use is associated with the occurrence of age-related lens opacities (nuclear, cortical, and posterior subcapsular). METHODS: Surviving members of the original cohort of the Framingham Heart Study who also participated in the Framingham Eye Study (1986-1989) were examined for the absence or presence of lens opacities. Data from the Framingham Heart Study, including information on menopausal status (collected biennially from approximately 1948) and use of estrogen replacement therapy (collected biennially from approximately 1960) were used to examine associations between lens opacities and duration of postmenopausal estrogen use, type of menopause, and age at menopause. Five hundred twenty-nine women, aged 66 to 93 years, were included. Multivariable-adjusted odds ratios of specific types of lens opacities were calculated for (1) duration of estrogen use (never and 1-2, 3-9, and >/=10 years), (2) surgical vs natural menopause, and (3) age at menopause. RESULTS: Longer duration of postmenopausal estrogen therapy was inversely associated with the presence of nuclear lens opacities in an adjusted model. Women who had taken estrogen for 10 years or longer had a 60% reduction in risk compared with nonusers (odds ratio, 0.4; 95% confidence interval, 0.2-1.01). Longer duration of estrogen use was associated with fewer posterior subcapsular opacities at a borderline level of significance. No association was noted for cortical opacities. The risk of posterior subcapsular opacities was significantly increased for women who had undergone surgical menopause compared with women with natural menopause (odds ratio, 2.2; 95% confidence interval, 1.1-4.3). No association was noted for lens opacities and age at menopause. CONCLUSION: Data from our study and other studies suggest that a reduction in the risk of lens opacities may be an additional benefit of postmenopausal estrogen use.

Aged↗

PubMed2001

Dynamics and thermodynamics of hyperthermophilic proteins by hydrogen exchange.

The naturally occurring hydrogen exchange of protein molecules can provide nonperturbing site-resolved measurements of protein stability and flexibility and changes therein. The measurement and understanding of these issues is especially pertinent to studies of thermophilic proteins. This chapter briefly reviews the considerations necessary for measuring hydrogen exchange and translating HX measurements into these detailed protein parameters.

Archaeal Proteins↗

PubMed2000

An unknown endogenous inhibitor of Na/Ca exchange can enhance the cardiac muscle contractility.

The cardiac sarcolemma Na/Ca exchanger is a key system for controlling the intracellular calcium levels during the excitation-contraction coupling. Here, we test the hypothesis that the heart tissue contains a putative endogenous factor having a capacity to modulate the Na/Ca exchanger and muscle contractility. The concentrated cardiac extracts inhibit the Na(i)- or Ca(i)-dependent (45)Ca uptakes in isolated cardiac sarcolemma vesicles as well as the Na(o)-dependent Ca efflux, monitored by extravesicular Ca probe fluo-3. The inhibitory activity has been purified approximately 2000-fold by normal and reversed-phase HPLC procedures. The inhibitory activity is eluted from the Sephadex G-10 in the range of 350-550 Da, suggesting that the inhibitory factor is a low-molecular-weight substance. The mass spectra analysis shows a number of signals within m/z 380-560; however, it is not clear at this moment whether these recordings represent the mass of putative inhibitory factor or irrelevant impurities. The endogenous inhibitory factor of Na/Ca exchange does not resemble the properties (HPLC retention time, mass spectra, amino acid analysis, etc.) of autoinhibitory XIP peptide. The addition of inhibitory factor to muscle strip of guinea pig ventricles induces 2- to 5-fold enhancement of isometric contractions, thereby exhibiting a strong positive inotropic effect. This effect is a dose-dependent phenomenon, which can be reversed by washing the inhibitory factor from the organ bath. Assuming a molecular weight of 350-550 Da, the effective concentrations of putative inhibitor must be <10(-6) M. Therefore, the present findings demonstrate that the mammalian heart contains a low-molecular-weight factor that can inhibit Na/Ca exchange and enhance the cardiac contractility.

Aniline Compounds↗

PubMed2000

Transposition and exon shuffling by group II intron RNA molecules in pieces.

In the realms of RNA, transposable elements created by self-inserting introns recombine novel combinations of exon sequences in the background of replicating molecules. Although intermolecular RNA recombination is a wide-spread phenomenon reported for a variety of RNA-containing viruses, direct evidence to support the theory that modern splicing systems, together with the exon-intron structure, have evolved from the ability of RNA to recombine, is lacking. Here, we used an in vitro deletion-complementation assay to demonstrate trans-activation of forward and reverse self-splicing of a fragmented derivative of the group II intron bI1 from yeast mitochondria. We provide direct evidence for the functional interchangeability of analogous but non-identical domain 1 RNA molecules of group II introns that result in trans-activation of intron transposition and RNA-based exon shuffling. The data extend theories on intron evolution and raise the intriguing possibility that naturally fragmented group III and spliceosomal introns themselves can create transposons, permitting rapid evolution of protein-coding sequences by splicing reactions.

Base Sequence↗

PubMed2000

Conventional high resolution versus fast T(2)-weighted MR imaging of the heart: assessment of reperfusion induced myocardial injury in an animal model.

Cardiac image quality in terms of spatial resolution and signal contrast was assessed for conventional and newly developed T(2)-weighted fast spin-echo imaging with high k-space segmentation. The capability in revealing regional myocardial edema and cellular damage was examined by a porcine model using histopathologic correlation. Twelve porcine hearts were excised from slaughtered animals and instantly perfused with 1000 mL cold cardioplegic solution. After 4 h of cold ischemia the hearts were reperfused for one hour using a "Langendorff" perfusion model followed by MR imaging at 1.5 Tesla. Three additional pig hearts served as controls and were studied by MR directly after harvesting. Histopathological analysis of regional tissue changes was performed macro- and microscopically. Short axis T(2)-weighted (3000/45 and 90) high quality fast spin-echo (FSE) images were recorded without cardiac action and signal intensity was correlated with histology. These images also served as gold standard for evaluation of newly developed faster sequences allowing measuring times shorter than 20 s. Fast T(2)-weighted imaging comprised single-slice fast spin echo (moderate echo train length of 23 echoes, FSE(m)), and multi-slice single-shot half-Fourier fast spin-echo (71 echoes, FSE(HASTE)) sequences, supplemented by versions with inversion recovery preparation (FSE(m)IR and FSE(HASTE)IR). Systolic function after reperfusion was restored in 10 porcine hearts. Tissue alterations included myocardial edema and contraction band necrosis which was found to be most severe in myocardium with maximum T(2) SI. Especially FSE(m) and FSE(m)IR sequences allowed differentiation of all categories of tissue damage on a high level of significance. In contrast, single-shot FSE(HASTE) and FSE(HASTE)IR sequences did not provide sufficient image quality to discriminate moderate and severe myocardial damage (p > 0.05). Different degrees of myocardial injury after ischemia and reperfusion can be staged by MR imaging, especially using conventional high resolution T(2)-weighted FSE sequences. The animal study indicates that fast T(2)-weighted FSE(m) and FSE(m)IR sequences lead to superior image quality and diagnostic accuracy compared to FSE(HASTE) and FSE(HASTE)IR imaging.

Analysis of Variance↗

PubMed1999

Clinical course of macular holes: the Eye Disease Case-Control Study.

OBJECTIVE: To describe the clinical course of affected and unaffected eyes in patients with idiopathic macular holes. PATIENTS: Prospective study of patients with macular holes enrolled in the Eye Disease Case-Control Study. MAIN OUTCOME MEASURES: The best-corrected visual acuity at follow-up was compared with that at baseline. Changes in the macular holes, including increases in size or spontaneous regression, were assessed. The rates of development of new macular holes in fellow unaffected eyes were estimated. RESULTS: Of the 198 patients examined at baseline, 28 (14.1%) died before reevaluation. Of those who survived, 122 (71.8%) had a follow-up examination. Approximately 34% (34.4%) of all eyes with macular holes had an increase in the size of the macular hole. Forty-five percent of eyes had a decrease in visual acuity of 2 or more lines and 27.8%, of 3 or more lines; 40.9% remained stable, with a gain or loss of fewer than 2 lines. The rate of development of a new macular hole during follow-up in fellow eyes that were unaffected at baseline was 4.3% for 3 or fewer years of follow-up, 6.5% for 4 to 5 years of follow-up, and 7.1% for 6 or more years of follow-up. Spontaneous regression of the macular hole occurred in 3 (8.6%) of 35 patients with a follow-up interval of 6 or more years, whereas no regression occurred in patients with a shorter follow-up. CONCLUSIONS: The visual acuity of 45.0% of eyes with macular holes deteriorated by 2 or more lines during follow-up. The rate of development of macular holes in unaffected fellow eyes was low.

Adult↗

PubMed1999

High intraocular pressure and survival: the Framingham Studies.

PURPOSE: To examine whether high intraocular pressure (greater than or equal to 25 mm Hg) or a history of treatment for glaucoma is associated with decreased survival and, if so, how such ocular markers might be explained. METHODS: Eye examinations, including applanation tonometry, were conducted on members of the Framingham Eye Study cohort from February 1, 1973, to February 1, 1975. Participants who reported a history of treatment for glaucoma were identified. Survival data, including information on the date of death, were available from the time of the Eye Study through March 31, 1990. RESULTS: Of the 1,764 persons under the age of 70 years at the baseline eye examination, 1,421 persons had low intraocular pressure (< or =20 mm Hg), 264 persons had medium intraocular pressure levels (20 to 24 mm Hg), and 79 persons had high intraocular pressure (> or =25 mm Hg) or history of glaucoma treatment. During the follow-up period, 29%, 30%, and 47% died in the groups with low, medium, and high intraocular pressure (or history of glaucoma treatment), respectively. In an age-and-sex adjusted Cox proportional hazards analysis, the death rate ratio for the group with medium intraocular pressure relative to the group with low intraocular pressure was 1.04. The corresponding death rate ratio for the group with high intraocular pressure was 1.56 with a 95% confidence interval of 1.11 to 2.19 (P < .001). After adjustment for age, sex, hypertension, diabetes, cigarette smoking, and body mass index, a positive relationship remained, but at a borderline level of significance (P = .075). CONCLUSIONS: High intraocular pressure or the presence of glaucoma is a marker for decreased life expectancy in the Framingham Eye Study cohort. The relationship is present even after adjustment for risk factors known to be associated with higher mortality such as age, sex, hypertension, diabetes, cigarette smoking, and body mass index. Special attention to the general health status of patients with high intraocular pressure or glaucoma seems warranted.

Aged↗

PubMed1999

Left leg paralysis in a renal transplant.

The postoperative course of renal transplant patients is often complicated by opportunistic infection. Up to 4% of posttransplant infections are caused by Nocardia species. We present an unusual case of a nocardial spinal cord abscess that caused left leg paralysis.

Abscess↗

PubMed1998

Risk factors for hemiretinal vein occlusion: comparison with risk factors for central and branch retinal vein occlusion: the eye disease case-control study.

OBJECTIVE: Possible risk factors for hemiretinal vein occlusion were identified and compared with risk factor profiles for central and branch retinal vein occlusion. DESIGN: The design was a multicenter case-control study. METHODS: The authors identified 79 patients with hemiretinal vein occlusion (HRVO), 258 patients with central retinal vein occlusion (CRVO), 270 patients with branch retinal vein occlusion (BRVO), and 1142 control subjects at 5 clinical centers. Risk factor data were obtained through interviews, clinical examinations, and laboratory analyses of blood specimens. RESULTS: Systemic hypertension and history of diabetes mellitus were associated with increased risk of HRVO. Risk of CRVO increased with history of diabetes, systemic hypertension, and higher erythrocyte sedimentation rate (females only); risk of CRVO decreased with increasing amounts of physical activity and increasing amounts of alcohol consumption. Systemic hypertension, higher body mass index, and higher alpha2-globulin levels were associated with increased risk of BRVO, whereas higher high-density lipoprotein levels and increasing levels of alcohol consumption were associated with decreased risk of BRVO. Glaucoma history was associated with all three types of retinal vein occlusion. CONCLUSION: Patients presenting with retinal vein occlusion should be evaluated for cardiovascular disease, diabetes, and glaucoma.

Adult↗

PubMed1998

A longitudinal study of body mass index and lens opacities. The Framingham Studies.

OBJECTIVE: The purpose of the study was to determine whether body mass index (BMI) is an independent risk factor for the development of nuclear, cortical, or posterior subcapsular lens opacities. DESIGN: A cohort study. PARTICIPANTS AND METHODS: Eye examinations were conducted on surviving members of the Framingham Heart Study Cohort from 1973 to 1975 (Framingham Eye Study I) and again from 1986 to 1989 (Framingham Eye Study II). Data from the Framingham Heart Study, including weight measurements collected biennially from 1948, were used to examine associations between BMI (mean BMI across examinations, slope of BMI over time, and fluctuations in BMI) and the development of lens opacities. This analysis included 714 individuals, aged 52-80 years, who were free of lens opacities at the first eye examination. MAIN OUTCOME MEASURES: Development of nuclear, cortical, and posterior subcapsular lens opacities. RESULTS: A total of 444 persons developed lens opacities during the approximately 13 years between eye examinations. In logistic regression analyses that controlled for age, sex, education, diabetes, and smoking, the risk of developing cortical opacity increased with higher BMI at the time of the first eye examination (P = 0.002). Risk of cortical opacities also increased, at a borderline level of significance, with higher average BMI (P = 0.09) across examinations and increasing BMI levels over time (P = 0.10). There was a strong association between increasing BMI over time and the development of posterior subcapsular lens opacities (P = 0.002). No associations were found for nuclear lens opacities. CONCLUSIONS: Although the mechanism explaining the association is unclear, these findings suggest that BMI, a potentially modifiable characteristic, is associated with the development of cortical and posterior subcapsular lens opacities.

Aged↗

PubMed1997

Stability and dynamics in a hyperthermophilic protein with melting temperature close to 200 degrees C.

The rubredoxin protein from the hyperthermophilic archaebacterium Pyrococcus furiosus was examined by a hydrogen exchange method. Even though the protein does not exhibit reversible thermal unfolding, one can determine its stability parameters-free energy, enthalpy, entropy, and melting temperature-and also the distribution of stability throughout the protein, by using hydrogen exchange to measure the reversible cycling of the protein between native and unfolded states that occurs even under native conditions.

Circular Dichroism↗

PubMed1997

Cigarette smoking and the risk of development of lens opacities. The Framingham studies.

OBJECTIVE: To examine the association between cigarette smoking and the incidence of nuclear and non-nuclear lens opacities in members of the Framingham Eye Study Cohort. PARTICIPANTS AND METHODS: Eye examinations were conducted on surviving members of the Framingham Heart Study Cohort from 1973 to 1975 (Framingham Eye Study I) and again from 1986 to 1989 (Framingham Eye Study II). Smoking data, collected biennially since 1948 in the Heart Study, were used to examine the relationship between cigarette smoking and the incidence of lens opacities. Two thousand six hundred seventy-five persons were examined in the Framingham Eye Study I. Our analysis included 660 persons, aged 52 to 80 years, who were free of lens opacities at the first eye examination. RESULTS: During the approximately 12.5 years between eye examinations, lens opacities developed in a total of 381 persons, with nuclear opacities constituting the most frequent type. In logistic regression analyses that controlled for age, sex, education, and diabetes, a significant positive association with increasing duration of smoking and number of cigarettes smoked daily was found for nuclear lens opacities, alone or in combination (test for trend, P < or = .002), but not for nonnuclear opacities (test for trend, P = .62). Among the heavier smokers (persons who smoked > or = 20 cigarettes per day according to 6 or more biennial Framingham Heart Study examinations), 77% were still smoking at the time of the first eye examination. Persons who smoked 20 or more cigarettes per day at the time of the first eye examination were at substantially increased risk for the development of nuclear opacities than nonsmokers (odds ratio, 2.84; 95% confidence interval, 1.46-5.51). There was no apparent excess risk for persons with nonnuclear lens opacities (odds ratio, 1.42; 95% confidence interval, 0.65-3.07). CONCLUSION: This study provides further evidence that cigarette smokers have an increased risk of developing nuclear lens opacities. The risk was greatest for heavier smokers, who tended to be current smokers and who smoked more cigarettes and for a longer duration.

Aged↗

PubMed1996

Associations of types of lens opacities between and within eyes of individuals: an application of second-order generalized estimating equations. The Framingham Eye Studies Group.

The lens opacity characteristics of individuals constitute multivariate data. Our goal was to estimate the associations between the three main types of age-related lens opacities (nuclear, cortical, posterior subcapsular) both between and within eyes of individuals using cross-sectional data from the Framingham (Massachusetts) Eye Studies. We describe use of a recently proposed extension of the generalized estimating equations approach to marginal logistic models (GEE2), and we demonstrate that a variety of research problems can be investigated with this methodology. For example, in our data, there were strong associations of the same opacity types between the two eyes of individuals and weak associations between different types of opacities. We also note that estimation of such associations may be limited in other epidemiologic settings.

Age Factors↗

PubMed1995

Serum zinc and serum lipid profiles in 778 adults.

There has been increasing use of high-dosage zinc supplementation in the population, in particular as a potential treatment for age-related macular degeneration. We examined the relationship between fasting serum zinc and serum lipid levels in 778 adults, aged 22 to 80 years, who were control subjects in a multicenter, clinic-based case-control study. The samples were taken during 1987 to 1990, a time when vitamin/mineral supplementation was becoming increasingly common. We found that higher serum zinc levels, most notably those above the highest quintile, were associated with higher levels of total serum cholesterol, low-density-lipoprotein cholesterol, and triglycerides. No significant trend was noted for high-density-lipoprotein cholesterol. Previous studies demonstrated that high-dosage zinc supplements raise serum zinc levels. The possibility that use of such supplements can adversely affect serum lipid profiles suggests that chronic ingestion of such supplements should not be done without adequate medical supervision.

Adult↗