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Biomedical subjects

J Frank

Publications and source records attributed to J Frank.

At least 19 recordsLinked to original sources
PubMed2006

The effect of voluntary arm abduction on balance recovery following multidirectional stance perturbations.

The goal of this study was to investigate how voluntarily abducting one arm, 90 degrees at onset of a rotational perturbation of the support surface, influences the recovery of upright stance. Young adults were tested under four stance conditions: abducting one arm to the horizontal only (AO); perturbation of stance using a support surface rotation only (PO); combined support surface rotation and abduction of the downhill arm, ipsilateral to tilt (IPS); and fourth abduction of the uphill, contralateral arm (CON). Simultaneous auditory and visual trigger cues were used for arm raising. Perturbations consisted of six directions of combined support surface roll and pitch rotation (7.5 degrees and 60 degrees/s). Outcome measures were whole body centre of mass (COM) movements and body segment angular displacements recorded with a motion analysis system, as well as leg, trunk, and arm EMG responses. Arm raises contralateral and ipsilateral to the direction of support surface roll were more rapid than in the AO condition and significantly reduced or increased, respectively, COM lateral displacements relative to the PO condition. The changes in COM displacements and velocities during combined CON arm raise and perturbation were greater than expected from the sum of displacements for AO and PO conditions alone, but less for the IPS condition. Arm raising increased trunk roll in a direction opposite arm raising was more than for the AO and PO conditions. Robust effects were also observed for hip abduction but not for leg flexion. Early balance correcting activity was enhanced on the side opposite arm raising and later stabilising activity reduced bilaterally in lower trunk muscles compared to summed activity for the AO and PO conditions. Similar effects were observed in gluteus medius muscles but effects were weak in ankle muscles. EMG onsets in muscles of the raised arm were earlier than in the AO conditions. We conclude that triggered arm abduction, contralateral to the direction of support surface rotation, had significant stabilization benefits for young adults and ipsilateral arm movements had destabilizing effects. The arm raises could be simultaneously executed with balance corrections. These results provide insights into the integration of balance corrections and voluntary commands into one automatic reaction that may be useful in training fall avoidance.

Adaptation, Physiological↗
PubMed2006

Mutations in the gene encoding the Wnt-signaling component R-spondin 4 (RSPO4) cause autosomal recessive anonychia.

Anonychia is an autosomal recessive disorder characterized by the congenital absence of finger- and toenails. In a large German nonconsanguineous family with four affected and five unaffected siblings with isolated total congenital anonychia, we performed genomewide mapping and showed linkage to 20p13. Analysis of the RSPO4 gene within this interval revealed a frameshift and a nonconservative missense mutation in exon 2 affecting the highly conserved first furin-like cysteine-rich domain. Both mutations were not present among controls and were shown to segregate with the disease phenotype. RSPO4 is a member of the recently described R-spondin family of secreted proteins that play a major role in activating the Wnt/ beta -catenin signaling pathway. Wnt signaling is evolutionarily conserved and plays a pivotal role in embryonic development, growth regulation of multiple tissues, and cancer development. Our findings add to the increasing body of evidence indicating that mesenchymal-epithelial interactions are crucial in nail development and put anonychia on the growing list of congenital malformation syndromes caused by Wnt-signaling-pathway defects. To the best of our knowledge, this is the first gene known to be responsible for an isolated, nonsyndromic nail disorder.

Adult↗
PubMed2006

Towards biochemical reaction monitoring using FT-IR synchrotron radiation.

A lab-on-a-chip device made of CaF2 windows and SU-8 polymer was used for fluid lamination to achieve rapid mixing of two streamlines with a cross section of 300 x 5 microm each. Time resolved measurements of the induced chemical reaction was achieved by applying constant feeding low flow rates and by on-chip measurement at defined distances after the mixing point. Synchrotron IR microscopic detection was employed for direct and label-free monitoring of (bio)chemical reactions. Furthermore, using synchrotron IR microscopy the measurement spot could be reduced to the diffraction limit, thus maximizing time resolution in the experimental set-up under study. Based on computational fluid dynamic simulations the principle of the set-up is discussed. Experimental results on the basic hydrolysis of methyl chloroacetate proved the working principle of the experimental set-up. First results on the interaction between the antibiotic vancomycin and a tripeptide (Ac2KAA) involved in the build up of the membrane proteins of gram-positive bacteria are presented.

Animals↗
PubMed2006

[Laboratory tests and therapeutic strategies for the porphyrias].

The porphyrias are a heterogeneous group of predominantly hereditary metabolic diseases resulting from a dysfunction of heme biosynthesis. Most of the porphyrias can manifest with a broad range of cutaneous symptoms on the sun-exposed areas of the body, whereas other variants reveal life-threatening acute neurological attacks. Further, mixed types of porphyrias exist. Besides the skin, other organs can be affected, such as the liver and the central nervous system. Therefore, interdisciplinary supervision of these patients is mandatory. In this review we will first present the clinical picture and diagnosis of the porphyrias, including the specific biochemical laboratory tests and a diagnostic algorithm. Thereafter, the current therapeutic concepts will be briefly addressed. Finally, we introduce the European Porphyria Initiative (EPI), an association of various European porphyria centers that is aiming at gathering the broad experience of internationally renowned porphyria experts for the development of European consensus guidelines for diagnosis and treatment of these metabolic disorders.

Algorithms↗
PubMed2006

[Hereditary photodermatoses].

Hereditary photodermatoses are characterized by an increased photosensitivity caused by an inherited single gene defect. With few exceptions, they manifest in early childhood, reveal heterogeneous clinical symptoms, and are difficult to treat. Although these diseases are rare, it is very important to make an accurate diagnosis on the basis of clinical symptoms, specific diagnostic tests, and direct DNA analysis. We review the spectrum of inherited photodermatoses, including porphyria cutanea tarda, erythropoietic protoporphyria, actinic prurigo, Kindler syndrome, and disorders associated with a defect in DNA repair, including xeroderma pigmentosum, trichothiodystrophy, Cockayne syndrome, and Bloom syndrome. Early diagnosis may prevent complications associated with prolonged unprotected exposure to sunlight and makes it possible to offer genetic counseling and, when indicated, prenatal diagnosis to families at risk for these rare heritable disorders.

Diagnosis, Differential↗
PubMed2006

Genetic association of the human corticotropin releasing hormone receptor 1 (CRHR1) with binge drinking and alcohol intake patterns in two independent samples.

To investigate the role of the corticotropin releasing hormone receptor 1 (CRHR1) in patterns of human alcohol drinking and its potential contribution to alcohol dependence, we analysed two independent samples: a sample of adolescents, which consisted of individuals from the 'Mannheim Study of Risk Children' (MARC), who had little previous exposure to alcohol, and a sample of alcohol-dependent adults, who met DSM-IV criteria of alcohol dependence. Following determination of allelic frequencies of 14 polymorphisms of the CRHR1 gene, two haplotype tagging (ht)SNPs discriminating between haplotypes with a frequency of > or =0.7% were identified. Both samples were genotyped and systematically examined for association with the htSNPs of CRHR1. In the adolescent sample, significant group differences between genotypes were observed in binge drinking, lifetime prevalence of alcohol intake and lifetime prevalence of drunkenness. The sample of adult alcohol-dependent patients showed association of CRHR1 with high amount of drinking. This is the first time that an association of CRHR1 with specific patterns of alcohol consumption has been reported. Our findings support results from animal models, suggesting an importance of CRHR1 in integrating gene-environment effects in alcohol use disorders.

Adolescent↗
PubMed2006

A Chilean boy with severe photosensitivity and finger shortening: the first case of homozygous variegate porphyria in South America.

A 7-year-old Chilean boy presented with severe photosensitivity, blistering, erosions and scarring on sun-exposed areas of the body since the age of 6 months. Additionally, he showed a short stature and shortening of the fingers. Laboratory examination revealed greatly elevated protoporphyrin levels in the blood. Such biochemical findings can be observed in homozygous variants of usually autosomal dominantly inherited acute porphyrias such as variegate porphyria (VP) and hereditary coproporphyria, which usually do not become manifest before the second or third decade of life in heterozygotes. Using polymerase chain reaction-based techniques we identified a missense mutation in exon 7 on the paternal allele and a frameshift mutation in exon 13 on the maternal allele of the protoporphyrinogen oxidase gene that harbours the mutations underlying VP. This is the first homozygous case of VP in South America. As VP represents the most frequent type of acute porphyria not only in Chile but also in South Africa, more such cases could be expected in the future, particularly because a founder mutation for this disease has already been described in the Chilean and South African population.

Child↗
PubMed2006

Focused ion beam milling of vitreous water: prospects for an alternative to cryo-ultramicrotomy of frozen-hydrated biological samples.

The feasibility of using a focused ion beam (FIB) for the purpose of thinning vitreously frozen biological specimens for transmission electron microscopy (TEM) was explored. A concern was whether heat transfer beyond the direct ion interaction layer might devitrify the ice. To test this possibility, we milled vitreously frozen water on a standard TEM grid with a 30-keV Ga(+) beam, and cryo-transferred the grid to a TEM for examination. Following FIB milling of the vitreous ice from a thickness of approximately 1200 nm to 200-150 nm, changes characteristic of heat-induced devitrification were not observed by TEM, in either images or diffraction patterns. Although numerous technical challenges remain, it is anticipated that 'cryo-FIB thinning' of bulk frozen-hydratred material will be capable of producing specimens for TEM cryo-tomography with much greater efficiency than cryo-ultramicrotomy, and without the specimen distortions and handling difficulties of the latter.

Cryoultramicrotomy↗
PubMed2006

Barber's hair sinus in a female hairdresser: uncommon manifestation of an occupational dermatosis.

Hairdressers are prone to developing occupational skin diseases, particularly hand eczema of different origins. Rather uncommon, however, is the so-called barber's hair sinus that is caused by hair fragments penetrating the skin preferably in the interdigital spaces of their hands. Whereas, to date, the disease has almost exclusively been reported to occur on the hands of male hairdressers, we herein present the first case of a female hairdresser who developed a barber's hair sinus on one of her feet.

Barbering↗
PubMed2005

Herbicide binding and thermal stability of photosystem II isolated from Thermosynechococcus elongatus.

Binding of herbicides to photosystem II inhibits the electron transfer from Q(A) to Q(B) due to competition of herbicides with plastoquinone bound at the Q(B) site. We investigated herbicide binding to monomeric and dimeric photosystem II core complexes (PSIIcc) isolated from Thermosynechococcus elongatus by a combination of different methods (isothermal titration and differential scanning calorimetry, CD spectroscopy and measurements of the oxygen evolution) yielding binding constants, enthalpies and stoichiometries for various herbicides as well as information regarding stabilization/destabilization of the complex. Herbicide binding to detergent-solubilized PSIIcc can be described by a model of single independent binding sites present on this important membrane protein. Interestingly, binding stoichiometries herbicide:PSIIcc are lower than 1:1 and vary depending on the herbicide under study. Strong binding herbicides such as terbutryn stabilize PSIIcc in thermal unfolding experiments and endothermically binding herbicides like ioxynil probably cause large structural changes accompanied with the binding process as shown by differential scanning calorimetry experiments of the unfolding reaction of PSIIcc monomer in the presence of ioxynil. In addition we studied the occupancy of the Q(B) sites with plastoquinone (PQ9) by measuring flash induced fluorescence relaxation yielding a possible explanation for the deviations of herbicide binding from a 1:1 herbicide/binding site model.

Binding Sites↗
PubMed2005

Monitoring of hematological, inflammatory and oxidative reactions to acute oral iron exposure in human volunteers: preliminary screening for selection of potentially-responsive biomarkers.

BACKGROUND: Iron is an essential micronutrient but also a major catalyst of oxidative and inflammatory reactions. OBJECTIVE: To evaluate the potential utility of selected biomarkers in blood or urine to indicate in vivo oxidative or inflammatory response to oral iron intake at pharmacological doses. METHODS: Three healthy volunteers provided morning, fasting samples of blood and urine on up to 13 study days--3 before, 7 during and 3 following a 7-consecutive-day period of receiving 120 mg of iron per day as ferrous sulfate in commercially available syrup. A series of 23 biomarkers were measured on each collection of biological fluids to monitor iron-responsive changes in biomarkers related to hematological or iron status, inflammation and in vivo oxidation. RESULTS: Among the inflammatory biomarkers measured, white blood cells, serum CRP and urinary neopterin showed no response to iron dosing. Only circulating interleukin-4 (IL-4) and TNF-alpha had abnormal responses with a time association to the oral iron intake. Among the oxidative biomarkers, expression of blood superoxide dismutase (SOD), hemoxygenase-1, catalase as well as circulating thiobarbituric acid reactive substances (TBARS), total oxidative capacity and carbonyl proteins were stable in response to iron exposure. Only urinary TBARS, 8-hydroxy-2-desoxyguanosine and isoprostanes evidenced consistent or suggestive responses to ingestion of the iron challenge. Serum hepcidin concentration increased dramatically in all three subjects after only the first 120 mg dose of iron, and remained elevated even 9 days after cessation of the iron intervention. CONCLUSIONS: Most of the candidate biomarkers show very limited promise as response-indicators to oral iron dosing at the 120 mg dosages or lower, but circulating IL-4, TNF-alpha as well as urinary TBARS, 8-hydroxy-2-desoxyguanosine and isoprostanes showed potential utility as reliable indicators of oxidative and inflammatory response to oral ferrous sulfate.

Administration, Oral↗
PubMed2004

Mid-IR synchrotron radiation for molecular specific detection in microchip-based analysis systems.

Microstructures constructed from SU-8 polymer and produced on CaF(2) base plates have been developed for microchip-based analysis systems used to perform FTIR spectroscopic detection using mid-IR synchrotron radiation. The high brilliance of the synchrotron source enables measurements at spot sizes at the diffraction limit of mid-IR radiation. This corresponds to a spatial resolution of a few micrometers (5-20 microm). These small measurement spots are useful for lab-on-a-chip devices, since their sizes are comparable to those of the structures usually used in these devices. Two different types of microchips are introduced here. The first chip was designed for time-resolved FTIR investigations of chemical reactions in solution. The second chip was designed for chip-based electrophoresis with IR detection on-chip. The results obtained prove the operational functionality of these chips, and indicate the potential of these new devices for further applications in (bio)analytical chemistry.

Journal Article↗
PubMed2004

[Adiponecrosis subcutanea neonatorum in congenital pneumonia].

In the course of a connatal pneumonia, a 7-day-old female newborn developed symmetrical subcutaneous nodules on her back, shoulders, and upper arms. These skin lesions were accompanied by hypercalcemia. Histological examination confirmed the putative clinical diagnosis of subcutaneous fat necrosis of the newborn. We discuss the differential diagnoses, therapeutic strategies, and prognosis of this uncommon disorder of the fat tissue.

Biopsy↗
PubMed2004

[Unilateral cheek tumor. Case report and differential diagnoses].

A 56-year-old male presented with a tumor on the cheek that had developed over 5 months. Unexpectedly, histological and immunohistochemical studies revealed an adenocarcinoma of the salivary gland. We discuss the differential diagnoses of tumors of the cheek.

Adenocarcinoma↗
PubMed2004

[Progressive symmetric erythrokeratodermia of Darier-Gottron].

A 5 1/2-year-old boy revealed symmetric erythematous plaques on both arms and legs as well as in the face. Additionally, contractions of several digital joints were noted. We diagnosed a progressive symmetric erythrokeratoderma and initiated a topical therapy with tretinoin. Here we discuss the etiology, differential diagnoses, and therapeutic options of this rare disorder of keratinization.

Administration, Topical↗