Biomedical subjects

E Ritter

Publications and source records attributed to E Ritter.

At least 19 recordsLinked to original sources

PubMed2005

QTL analysis of fruit components in the progeny of a Rennell Island Tall coconut (Cocos nucifera L.) individual.

We investigated the genetic factors controlling fruit components in coconut by performing QTL analyses for fruit component weights and ratios in a segregating progeny of a Rennell Island Tall genotype. The underlying linkage map of this population was already established in a previous study, as well as QTL analyses for fruit production, which were used to complement our results. The addition of 53 new markers (mainly SSRs) led to minor amendments in the map. A total of 52 putative QTLs were identified for the 11 traits under study. Thirty-four of them were grouped in six small clusters, which probably correspond to single pleiotropic genes. Some additional QTLs located apart from these clusters also had relatively large effects on the individual traits. The QTLs for fruit component weight, endosperm humidity and fruit production were found at different locations in the genome, suggesting that efficient marker-assisted selection for yield can be achieved by selecting QTLs for the individual components. The detected QTLs descend from a genotype belonging to the "Pacific" coconut group. Based on the known molecular and phenotypic differences between "Pacific" and "Indo-Atlantic" coconuts, we suggest that a large fraction of coconut genetic diversity is still to be investigated by studying populations derived from crosses between these groups.

Chromosome Mapping↗

PubMed2005

Microsatellite-based high density linkage map in oil palm (Elaeis guineensis Jacq.).

A microsatellite-based high-density linkage map for oil palm (Elaeis guinensis Jacq.) was constructed from a cross between two heterozygous parents, a tenera palm from the La Me population (LM2T) and a dura palm from the Deli population (DA10D). A set of 390 simple sequence repeat (SSR) markers was developed in oil palm from microsatellite-enriched libraries and evaluated for polymorphism along with 21 coconut SSRs. A dense and genome-wide microsatellite framework as well as saturating amplified fragments length polymorphisms (AFLPs) allowed the construction of a linkage map consisting of 255 microsatellites, 688 AFLPs and the locus of the Sh gene, which controls the presence or absence of a shell in the oil palm fruit. An AFLP marker E-Agg/M-CAA132 was mapped at 4.7 cM from the Sh locus. The 944 genetic markers were distributed on 16 linkage groups (LGs) and covered 1,743 cM. Our linkage map is the first in oil palm to have 16 independent linkage groups corresponding to the plant's 16 homologous chromosome pairs. It is also the only high-density linkage map with as many microsatellite markers in an Arecaceae species and represents an important step towards quantitative trait loci analysis and physical mapping in the E. guineensis species.

Arecaceae↗

PubMed2004

A full saturated linkage map of Picea abies including AFLP, SSR, ESTP, 5S rDNA and morphological markers.

Based on an F(1) progeny of 73 individuals, two parental maps were constructed according to the double pseudo-test cross strategy. The paternal map contained 16 linkage groups for a total genetic length of 1,792 cM. The maternal map covered 1,920 cM, and consisted of 12 linkage groups. These parental maps were then integrated using 66 intercross markers. The resulting consensus map covered 2,035 cM and included 755 markers (661 AFLPs, 74 SSRs, 18 ESTPs, the 5S rDNA and the early cone formation trait) on 12 linkage groups, reflecting the haploid number of chromosomes of Picea abies. The average spacing between two adjacent markers was 2.6 cM. The presence of 39 of the SSR and/or ESTP markers from this consensus map on other published maps of different Picea and Pinus species allowed us to establish partial linkage group homologies across three P. abies maps (up to five common markers per linkage group). This first saturated linkage map of P. abies could be therefore used as a support for developing comparative genome mapping in conifers.

Chromosome Mapping↗

PubMed2004

Genetic characterization of Erwinia amylovora strains by amplified fragment length polymorphism.

AIMS: Erwinia amylovora is one of the most important pathogens of pear and apple and is subject to strict quarantine regulations worldwide, although its patterns of dispersal are largely unknown. Previous attempts to fingerprint E. amylovora strains by molecular techniques have detected very little polymorphism because of the high genetic homogeneity of this bacterium. Our aim was to establish and test a typing method to quantify genetic diversity among strains of this plant pathogen. METHODS AND RESULTS: Twenty-two strains from different hosts and geographical locations were examined by PCR fingerprinting with four primers and by amplified fragment length polymorphism (AFLP) with four selected combinations of primers with a single base extension. PCR fingerprinting revealed little polymorphism producing the same amplification patterns for 17 strains, while the combined AFLP patterns yielded 78 polymorphic bands (34% of total bands) and allowed the differentiation of all but two strains. Clustering of strains in the resulting dendrogram was not correlated with host, year or country of isolation, and questions previous genealogies based on PFGE patterns. CONCLUSIONS: The AFLP technique allowed the detection of an unprecedented number of genetic markers in E. amylovora and proved to be the most useful tool so far for discriminating among strains of this pathogen. The results obtained in this study strongly suggest the occurrence of multiple introductions of the pathogen in Spain and other European countries. SIGNIFICANCE AND IMPACT OF THE STUDY: A major limitation in understanding the ecology of fire blight is the lack of typing techniques with a high power of discrimination. This study demonstrates the high resolution and the usefulness of the AFLP technique to differentiate among E. amylovora strains.

Biodiversity↗

PubMed2004

Use of forensic analysis to better understand shark attack behaviour.

Shark attacks have primarily been analyzed from wound patterns, with little knowledge of a shark's approach, behaviour and intention leading to such wounds. For the first time, during a shark-human interaction project in South Africa, a white shark, Carcharodon carcharias, was filmed biting a vertically positioned person at the water surface, and exhibiting distinct approach patterns leading to the bite. This bite was compared to ten white shark attacks that occurred (i) in the same geographical area of South Africa, and (ii) where the same body parts were bitten. Close similarity of some of these wound patterns to the bite imprint of the videotaped case indicate that the observed behaviour of the white shark may represent a common pattern of approaching and biting humans.

Animals↗

PubMed2002

[Vitamin supplements in oncology -- necessary, useful or superfluous?].

Vitamins are essential components of a normal diet, and sufficient amounts are always needed. Occasionally, multivitamin supplements may make sense in cancer patients. However, because of the balance of (antioxidant) vitamins, coenzymes, trace elements and secondary phytochemicals it offers, a varied diet of fresh fruits and vegetables is--wherever possible--to be preferred to supplements of single or combinations of vitamins. Although preclinical studies have confirmed the positive effects of high-dose vitamins on cancer, there is currently no evidence that increased consumption of vitamins benefits cancer patients--nor is the dose necessary to achieve a possible therapeutic impact known. Since a number of clinical and epidemiological studies fail to show any benefit, and adverse effects have even been reported, high-dose vitamins can at present be recommended only for short-term substitution in known vitamin deficiencies. Before a definitive pronouncement can be made, therefore, further clinical studies of megavitamins in cancer patients are needed.

Adult↗

PubMed2001

Signaling states of rhodopsin: absorption of light in active metarhodopsin II generates an all-trans-retinal bound inactive state.

Absorption of light in rhodopsin leads through 11-cis- and all-trans-retinal isomerization, proton transfers, and structural changes to the active G-protein binding meta-II state. When meta-II is photolysed by blue light absorption, the activating pathway is apparently reverted, and rhodopsin is photoregenerated. However, the product formed, a P subspecies with A(max) = 500 nm (P(500)), is different from the ground state based on the following observations: (i) the ground state fingerprint of 11-cis-retinal does not appear in the infrared spectra, although the proton transfers and structural changes are reverted; (ii) extraction of the retinal from P(500) does not yield the expected stoichiometric amount of 11-cis-retinal but predominantly yields all-trans-retinal; (iii) the infrared spectrum of P(500) is similar to the classical meta-III intermediate, which arises from meta-II by thermal decay; and (iv) both P(500) and meta-III can be photoconverted to meta-II with the same changes in the infrared spectrum and without a significant change in the isomerization state of the extracted chromophore. The data indicate the presence of a "second switch" between active and inactive conformations that operates by photolysis but without isomerization around the C(11)-C(12) double bond. This emphasizes the exclusivity of the ground state, which is only accessible by the metabolic regeneration with 11-cis-retinal.

Chromatography, High Pressure Liquid↗

PubMed2001

Mechanism of rhodopsin activation as examined with ring-constrained retinal analogs and the crystal structure of the ground state protein.

The guanine nucleotide-binding protein (G-protein)-coupled receptor superfamily (GPCR) is comprised of a large group of membrane proteins involved in a wide range of physiological signaling processes. The functional switch from a quiescent to an active conformation is at the heart of GPCR action. The GPCR rhodopsin has been studied extensively because of its key role in scotopic vision. The ground state chromophore, 11-cis-retinal, holds the transmembrane region of the protein in the inactive conformation. Light induces cis-trans isomerization and rhodopsin activation. Here we show that rhodopsin regenerated with a ring-constrained 11-cis-retinal analog undergoes photoisomerization; however, it remains marginally active because isomerization occurs without the chromophore-induced conformational change of the opsin moiety. Modeling the locked chromophore analogs in the active site of rhodopsin suggests that the beta-ionone ring rotates but is largely confined within the binding site of the natural 11-cis-retinal chromophore. This constraint is a result of the geometry of the stable 11-cis-locked configuration of the chromophore analogs. These results suggest that the native chromophore cis-trans isomerization is merely a mechanism for repositioning of the beta-ionone ring which ultimately leads to helix movements and determines receptor activation.

Animals↗

PubMed2001

Construction of a linkage map of the Rennell Island Tall coconut type (Cocos nucifera L.) and QTL analysis for yield characters.

AFLP and SSR DNA markers were used to construct a linkage map in the coconut (Cocos nucifera L.; 2n = 32) type Rennell Island Tall (RIT). A total of 227 markers were arranged into 16 linkage groups. The total genome length corresponded to 1971 cM for the RIT map, with 5-23 markers per linkage group. QTL analysis for yield characters in two consecutive sampling periods identified nine loci. Three and two QTLs were detected for number of bunches and one and three QTLs for number of nuts. The correlation of trait values between characters and evaluation periods is partially reflected in identical QTLs. The QTLs represent characters that are important in coconut breeding. The cosegregation of markers with these QTLs provides an opportunity for marker-assisted selection in coconut breeding programmes.

Chromosome Mapping↗

PubMed2000

FTIR spectroscopy of complexes formed between metarhodopsin II and C-terminal peptides from the G-protein alpha- and gamma-subunits.

Metarhodopsin II (MII) provides the active conformation of rhodopsin for interaction with the G-protein, Gt. Fourier transform infrared spectra from samples prepared by centrifugation reflect the pH dependent equilibrium between MII and inactive metarhodopsin I. C-terminal synthetic peptides (Gtalpha(340-350) and Gtgamma(60-71)farnesyl) stabilize MII. We find that both peptides cause similar spectral changes not seen with control peptides (Gtalpha (K341R, L349A) and non-farnesylated Gtgamma). The spectra reflect all the protonation dependent bands normally observed when MII is formed at acidic pH. Beside the protonation dependent bands, additional features, similar with both peptides, appear in the amide I and II regions.

Animals↗

PubMed2000

[Surgical vs. conservative treatment of fractures of the thoracolumbar transition].

A total of 86 patients suffering from fractures of the thoracolumbar spine were followed up after an average time period of 57 months (12-98). Of these patients, 56 were treated operatively and 30 conservatively. According to the AO/ASIF classification, 66% of the operated group were fractures of type A, 29% of type B, and 5% of type C. All patients were operated on by means of dorsal locking instrumentation with pedicular fixation and, apart from six patients, with transpedicular cancellous bone grafting. The conservative group was treated according to the guidelines of Böhler with closed reduction, plaster cast, and rehabilitation program. All fractures in the conservative group were of type A. At follow-up of all operated cases, the local gibbus angle had improved by a reduction of on average 18.6 degrees and was followed by a loss of correction of 12.5 degrees ending in a final gain of 6.1 degrees at follow-up. At follow-up of the conservatively treated cases, the local gibbus angle showed an improvement of 11.1 degrees at reduction and a loss of correction of 14.9 degrees after reduction. The remaining result was -3.6 degrees, that means an increase of kyphoses compared to the x-ray at admission. In order to be able to compare two homogeneous groups only fractures of type A were used. Comparison of the two groups showed an improvement of the vertebral body angle of 70% (11.3 degrees) after reduction in the surgical group and 46% (6.1 degrees) in the conservatively treated group. The subsequent loss of correction was 19% (3 degrees) in the surgical and 34% (4.5 degrees) in the conservatively treated group. The remaining gain at follow-up was 51% (8.3 degrees) in the surgical and only 12% (1.6 degrees) in the conservative group. The local gibbus angle had improved on average by 17.1 degrees after reduction in the surgical and by 11.1 degrees in the conservatively treated group. Loss of correction was 71% (12.2 degrees) and 132% (14.9 degrees), respectively. The final result at follow-up showed a decrease of kyphosis of 4.9 degrees in the surgical and an increase of kyphosis of 3.7 degrees in the conservatively treated group. The difference was significant. Within the surgical group, 75% of the loss of correction was caused by the discs and 25% by the vertebral body. In the conservatively treated group it was 69% and 31%, respectively. Concerning loss of correction, no difference was seen between patients with and without intercorporal bone grafting. There was no relationship between radiological and clinical outcome. Whereas 15% of the patients of the surgical group were not satisfied or moderately satisfied with the result, all patients in the conservatively treated group were satisfied or very satisfied. Based on the good clinical results of the conservative treatment we can conclude that in stable fractures without severe deformity, and in patients who are in bad general condition, conservative treatment can considered as an alternative to surgical treatment.

Adolescent↗

PubMed2000

Genetic linkage map of the edible basidiomycete Pleurotus ostreatus.

We have constructed a genetic linkage map of the edible basidiomycete Pleurotus ostreatus (var. Florida). The map is based on the segregation of 178 random amplified polymorphic DNA and 23 restriction fragment length polymorphism markers; four hydrophobin, two laccase, and two manganese peroxidase genes; both mating type loci; one isozyme locus (est1); the rRNA gene sequence; and a repetitive DNA sequence in a population of 80 sibling monokaryons. The map identifies 11 linkage groups corresponding to the chromosomes of P. ostreatus, and it has a total length of 1,000.7 centimorgans (cM) with an average of 35.1 kbp/cM. The map shows a high correlation (0.76) between physical and genetic chromosome sizes. The number of crossovers observed per chromosome per individual cell is 0.89. This map covers nearly the whole genome of P. ostreatus.

Chromosome Mapping↗

PubMed2000

Visceral leishmaniasis in mice devoid of tumor necrosis factor and response to treatment.

Tumor necrosis factor (TNF)-deficient mice were challenged with Leishmania donovani to characterize TNF in the response of visceral intracellular infection to antileishmanial chemotherapy. In wild-type controls (i) liver infection peaked at week 2 and resolved, (ii) discrete liver granulomas developed at weeks 2 to 4 and involuted, and (iii) leishmanicidal responses to antimony (Sb), amphotericin B (AmB), and miltefosine were intact. In TNF knockout (KO) mice (i) initial liver infection was unrestrained, plateaued, and then declined somewhat by week 6, (ii) an absent early granulomatous reaction abruptly accelerated with striking tissue inflammation, widespread hepatic necrosis, and 100% mortality by week 10, and (iii) while the initial response to AmB and miltefosine was intact, killing induced by Sb therapy was reduced by >50%. Although initial AmB treatment during weeks 2 to 3 killed 98% of liver parasites, 75% of AmB-treated KO mice subsequently relapsed and died by week 12; however, additional maintenance AmB preserved long-term survival. These results for a model of visceral infection indicate that endogenous TNF is required early on to control intracellular L. donovani, support granuloma development, and mediate optimal initial effects of Sb and prevent relapse after ordinarily curative AmB treatment. A compensatory, TNF-independent antileishmanial mechanism developed in TNF KO mice; however, its effect was uncontrolled fatal inflammation. Chemotherapeutic elimination of the parasite stimulus reversed the hyperinflammatory response and preserved survival.

Amphotericin B↗

PubMed2000

Transfer of the pectoralis major muscle for the treatment of irreparable rupture of the subscapularis tendon.

BACKGROUND: The clinical diagnosis of a tear of the subscapularis tendon is difficult, and the resulting delays frequently cause a major time-lapse before repair is attempted. Diagnostic delay often means that surgical repair is no longer possible. In twelve patients who had an irreparable tear of the subscapularis tendon, the superior one-half to two-thirds of the tendon of the pectoralis major muscle was used as a substitute for the subscapularis tendon. In order to adapt the orientation of the transferred muscle to that of the subscapularis, it was routed behind the conjoined tendon of the coracobrachialis muscle and the short head of the biceps to the lesser tuberosity. METHODS: The operations were performed between May 1993 and June 1997. The average age of the twelve patients was sixty-five years old (range, forty-nine to eighty-one years old). Eight patients had an isolated rupture of the subscapularis tendon, and four had a concomitant lesion in the form of either a partial or a complete rupture of the supraspinatus tendon. The dominant symptoms were anterior shoulder pain and weakness that had responded poorly to nonoperative therapy. Four patients also had signs of recurrent anterior instability. RESULTS: After an average follow-up interval of twenty-eight months (range, twenty-four to fifty-four months), nine of the twelve patients assessed the final result as excellent or good; three, as fair; and none, as poor. Pain was reduced, with the score improving from an average of 1.7 points (of a maximum of 15 points) preoperatively to an average of 9.6 points postoperatively. The patients' subjective functional evaluation improved from an average score of 20 points preoperatively to an average of 63 points postoperatively. The average functional rating with use of the Constant and Murley score increased from 26.9 to 67.1 percent of normal. All four preoperatively unstable shoulders were stable at the time of the latest follow-up. CONCLUSIONS: This repair technique can be recommended as a reconstructive procedure for elderly patients who have an irreparable tear of the subscapularis tendon.

Aged↗

PubMed1999

Recurrent ductal carcinoma in situ after total mastectomy.

A case report is presented of a woman with recurrent DCIS occurring several years following a total mastectomy, the diagnosis of which was aided by a subpectoral saline implant. A discussion of factors associated with recurrence and a review of the literature is provided. A role for selective use of mammography in screening postmastectomy reconstructed breasts in patients at high risk for recurrence is suggested.

Adult↗

PubMed1999

Measurement of blood flow and oxygen tension in adjacent tissues in pedicled and free flap head and neck reconstruction.

The purpose of this study was to evaluate blood flow and transcutaneous partial oxygen pressure (TcPO(2)) in adjacent tissues to free and pedicled flaps following reconstructive procedures used in conjunction with radical surgery for head and neck cancers. Fifty patients were included. Fourteen patients had reconstruction with pedicled flaps and 36 with free flaps. For each patient, TcPO(2) and laser Doppler flow measurements were taken at the center of the flap, in adjacent tissue, and in a corresponding contralateral site. Three laser Doppler measurements were performed at each site and a mean value recorded. All patients had undergone reconstruction up to 6 months prior to the time of the measurements. The collected data were analyzed using a Wilcoxon signed rank test. There were no statistically significant differences in partial oxygen tension or laser Doppler values between tissues adjacent to free compared to pedicled flaps. Although there is strong evidence to support that free flaps have improved blood flow and partial oxygen tension over pedicled flaps, further study is required to evaluate adjacent tissues. Flap choice may assist with alteration in blood flow in less favorable defects such as those in previously irradiated fields and those resulting from burn scars or chronic infections.

Adolescent↗

PubMed1999

Identification of incompatibility alleles and characterisation of molecular markers genetically linked to the A incompatibility locus in the white rot fungus Pleurotus ostreatus.

Pleurotus ostreatus is a hetertothallic homobasidiomycete whose mating is controlled by a bifactorial tetrapolar genetic system. Although this mechanism is well accepted, there is a lack of knowledge about its molecular basis, as the incompatibility loci have not been cloned and sequenced. As a first step towards the elucidation of the molecular structure of the A-type incompatibility locus, molecular markers have been isolated which correspond to genomic sequences present in different strains of P. ostreatus but not in other higher basidiomycetae. These markers reveal single-copy genetic regions in which some degree of genetic variability can be detected.

Alleles↗

PubMed1999

An encyclopedia of mouse genes.

The laboratory mouse is the premier model system for studies of mammalian development due to the powerful classical genetic analysis possible (see also the Jackson Laboratory web site, http://www.jax.org/) and the ever-expanding collection of molecular tools. To enhance the utility of the mouse system, we initiated a program to generate a large database of expressed sequence tags (ESTs) that can provide rapid access to genes. Of particular significance was the possibility that cDNA libraries could be prepared from very early stages of development, a situation unrealized in human EST projects. We report here the development of a comprehensive database of ESTs for the mouse. The project, initiated in March 1996, has focused on 5' end sequences from directionally cloned, oligo-dT primed cDNA libraries. As of 23 October 1998, 352,040 sequences had been generated, annotated and deposited in dbEST, where they comprised 93% of the total ESTs available for mouse. EST data are versatile and have been applied to gene identification, comparative sequence analysis, comparative gene mapping and candidate disease gene identification, genome sequence annotation, microarray development and the development of gene-based map resources.

Animals↗