[Uterus septus with primary infertility - an operating indication?]

OBJECTIVE

The following retrospective study is intended as a contribution towards determining the necessity of a hysteroscopic metroplasty in patients with primary infertility. -

MATERIAL AND METHODS

21 patients with primary infertility and a septate uterus, who had undergone a hysteroscopic dissection of the septum between 1993 and 2000, were evaluated. With the help of medical records, operation reports, standardised questionnaires as well as telephone contact with the patient's doctor and/or the patient, anamneses, operation as well as postoperative development were recorded. -

RESULTS

All dissections of the septum occurred without complication. During follow-up (median 24.0 +/- 23.7 months), 11/21 patients became pregnant (52.4 %). Of these 11 pregnancies, 7 ended (63.3 %) at full-term, 2 (18.2 %) prematurely and one (9.1 %) as a miscarriage. One pregnancy is currently in the 3(rd) trimester. -

CONCLUSIONS

The hysteroscopic metroplasty demonstrates a low intra- and postoperative rate of complication. Particularly the indication of a lower rate of miscarriages, possibly of an increase in the pregnancy rates, should, in our opinion, give reason to proceeding with a diagnostic hysteroscopy, especially prior to extensive sterility therapies. Where suspicion exists of a septum > 1.0 cm, this should be corrected by means of an operative hysteroscopy.

Single-molecule imaging of l-type Ca(2+) channels in live cells

L-type Ca(2+) channels are an important means by which a cell regulates the Ca(2+) influx into the cytosol on electrical stimulation. Their structure and dynamics in the plasma membrane, including their molecular mobility and aggregation, is of key interest for the in-depth understanding of their function. Construction of a fluorescent variant by fusion of the yellow-fluorescent protein to the ion channel and expression in a human cell line allowed us to address its dynamic embedding in the membrane at the level of individual channels in vivo. We report on the observation of individual fluorescence-labeled human cardiac L-type Ca(2+) channels using wide-field fluorescence microscopy in living cells. Our fluorescence and electrophysiological data indicate that L-type Ca(2+) channels tend to form larger aggregates which are mobile in the plasma membrane.

[Actions of standardized extracts of Crataegus berries on exercise tolerance and quality of life in patients with congestive heart failure]

Standardized extracts of Crataegus leaves and blossoms are said to have positive inotropic, positive dromotropic and negative bathmotropic effects. Clinical trials produce evidence for an improvement of symptoms in patients with congestive heart failure (NYHA II). In this trial the efficacy of a standardized extract of fresh Crataegus berries (Rob 10) on exercise tolerance and quality of life was studied in 88 patients. In a three-month placebo-controlled, randomized, double-blind trial these patients were treated with Rob 10 (3 x 25 drops daily). Total exercise time in bicycle ergometry was defined as primary efficacy variable, while quality of life (Minnesota Questionnaire), Dyspnea-Fatigue Index and the assessment of dyspnea by the patient on a visual analogous scale were chosen as secondary parameters. Investigations were performed after a two week placebo run-in period as well as 6 and 12 weeks after the onset of the study. Treatment with Rob 10 led to a increase of exercise time of 38.9 s vs placebo (95% confidence interval 5.7-72.1 s). Quality of life improved accordingly in favour of Rob 10. In the Minnesota Questionnaire, the total score fell by 31% (30.6 vs 44.1) under Rob 10 vs 18% (34.6 vs 42.4) under placebo. The Dyspnea-Fatigue Index demonstrated an increase of the total score of 12% (9.41 vs 8.37) vs 8% (8.92 vs 8.26) under administration of placebo. According to findings of the assessment of dyspnea by the patient, dyspnea decreased by 11% (50.5 vs 56.6 mm) vs 4% (54.8 vs 57.3 mm) under placebo. The present study proves the efficacy and safety of a standardized extract of fresh Crataegus berries (Rob 10) in patients with congestive heart failure (NYHA II) regarding the parameters evaluated.

Menorrhagia and adenomyosis in a patient with hyperhomocysteinemia, recurrent pelvic vein thromboses and extensive uterine collateral circulation treatment by supracervical hysterectomy

A 37-year-old patient had recurring thromboses, occlusion of the left femoral vein with hereditary hyperhomocysteinemia, hypermenorrhea and anaemia. Conservative therapy with endometrium ablation and gestagene failed. A supracervical hysterectomy was done to preserve the presacral and left lateral, dorsal and caudal collaterals beside the uterus, and prevent a postoperative congestion, especially of the left leg.

Construction and characterization of a BAC library for the molecular dissection of a single wild beet centromere and sugar beet (Beta vulgaris) genome analysis

We have constructed a sugar beet bacterial artificial chromosome (BAC) library of the chromosome mutant PRO1. This Beta vulgaris mutant carries a single chromosome fragment of 6-9 Mbp that is derived from the wild beet Beta procumbens and is transmitted efficiently in meiosis and mitosis. The library consists of 50,304 clones, with an average insert size of 125 kb. Filter hybridizations revealed that approximately 3.1% of the clones contain mitochondrial or chloroplast DNA. Based on a haploid genome size of 758 Mbp, the library represents eight genome equivalents. Thus, there is a greater than 99.96% probability that any sequence of the PROI genome can be found in the library. Approximately 0.2% of the clones hybridized with centromeric sequences of the PRO1 minichromosome. Using the identified BAC clones in fluorescence in situ hybridization experiments with PRO1 and B. procumbens chromosome spreads, their wild-beet origin and centromeric localization were demonstrated. Comparative Southern hybridization of pulsed-field separated PROI DNA and BAC inserts indicate that the centromeric region of the minichromosome is represented by overlapping clones in the library. Therefore, the PRO1 BAC library provides a useful tool for the characterization of a single plant centromere and is a valuable resource for sugar beet genome analysis.

Bilateral ovarian fibromas and endometrial adenocarcinoma in a postmenopausal patient with growing uterine myomas

Bilateral ovarian fibromas are a rare condition. We report a case of bilateral ovarian fibromas with endometrial adenocarcinoma in a postmenopausal woman who clinically showed symptoms of an estrogen-producing tumour. Clinical and histopathological problems in the pre- and intraoperative diagnostics of fibromas are discussed.

Identification of Lens culinaris ssp. culinaris chromosomes by physical mapping of repetitive DNA sequences

We describe the characterisation and the chromosomal localisation of two repeated DNA sequences, named pLc30 (466 bp long, 64% AT residues) and pLc7 (408 bp long, 61% AT residues), isolated from lentil (Lens culinaris ssp. culinaris) genomic DNA. The pLc30 family is characterised by four internal repeats organised in a head-to-tail orientation, whereas the pLc7 contains many short direct subrepeats. The two families do not share significant sequence similarity. The distribution of these repetitive sequences in different Lens species and in other legumes was investigated. pLc30 is present in all Lens species investigated but absent from other genera examined. In contrast, pLc7 is present also in the genome of other legumes. As determined by FISH, the pLc30 sequence hybridises on six out of seven lentil chromosome pairs, while pLc7 hybridises on one only. The distribution of the nine different hybridisation sites of pLc30 allows the discrimination of all seven chromosome pairs and the construction of a karyotype of L. culinaris ssp. culinaris. Additionally, the combination of simultaneous and successive FISH with pLc7, 5S rRNA, 18S-5.8S-25S rRNA genes, and a telomeric sequence allowed the assembly of a physical map based on lentil karyotype.

Functional characterization of the human Huntington's disease gene promoter

The genetic basis of neurodegeneration in Huntington's disease (HD) has been identified as a (CAG)(>37) repeat expansion in a gene of unknown function. Interestingly, patients with the same expanded (CAG)(n) repeat length may have markedly different ages at onset. Based on experiences in animal models the level of expression might be one of the modifying factors. To gain insight into the regulation of the human HD gene we functionally analyzed 2266 bp of the HD gene promoter region. This region lacks a TATA and a CAAT box, is GCrich, and it has several consensus sequences for SP1, AP-2 and AP-4 binding sites. The stretch between nucleotides -49 and -198 relative to the first ATG is highly conserved between human and rodents and it harbors several potential binding sites for transcription factors. We analyzed deletion mutants fused with the chloramphenicol acetyltransferase (CAT) reporter gene in transfected, huntingtin expressing neuronal (NS20Y) and non-neuronal (CHO) cell lines. Partial deletion of the evolutionarily conserved part of the promoter significantly reduces the activity in both neuronal and non-neuronal cells indicating that the core promoter activity is located between nucleotides -221 and 4, relative to the +1 translation start site. Binding affinities of DNA-protein interactions were defined by electrophoretic mobility shift assays and the protected nucleotide positions were determined by DNase I footprinting.

Soybean genomic survey: BAC-end sequences near RFLP and SSR markers

We are building a framework physical infrastructure across the soybean genome by using SSR (simple sequence repeat) and RFLP (restriction fragment length polymorphism) markers to identify BACs (bacterial artificial chromosomes) from two soybean BAC libraries. The libraries were prepared from two genotypes, each digested with a different restriction enzyme. The BACs identified by each marker were grouped into contigs. We have obtained BAC- end sequence from BACs within each contig. The sequences were analyzed by the University of Minnesota Center for Computational Genomics and Bioinformatics using BLAST algorithms to search nucleotide and protein databases. The SSR-identified BACs had a higher percentage of significant BLAST hits than did the RFLP-identified BACs. This difference was due to a higher percentage of hits to repetitive-type sequences for the SSR-identified BACs that was offset in part, however, by a somewhat larger proportion of RFLP-identified significant hits with similarity to experimentally defined genes and soybean ESTs (expressed sequence tags). These genes represented a wide range of metabolic functions. In these analyses, only repetitive sequences from SSR-identified contigs appeared to be clustered. The BAC-end sequences also allowed us to identify microsynteny between soybean and the model plants Arabidopsis thaliana and Medicago truncatula. This map-based approach to genome sampling provides a means of assaying soybean genome structure and organization.

[Clinical predictors of retinal detachment after open globe injury]

BACKGROUND

A retinal detachment after open globe injury has important prognostic and therapeutic implications.

MATERIAL AND METHODS

To determine whether retinal detachment following open globe injury could be predicted by clinical factors, we retrospectively evaluated 52 patients (52 eyes) with open globe injury admitted to our department. The Birmingham Eye Trauma Terminology System was used. Only patients which open eye injuries were evaluated. The results were registered during the 7 days after the accident.

RESULTS

In the week after the open globe injury, retinal detachment was present in 40.3 %. 100 % of the patients with previous cataract operation (with IOL) developed a retinal detachment (p < 0.01). Retinal detachment also correlated significantly with visual acuity less than hand movement and retained intraocular foreign bodies. 19 (95 %) of the 20 patients with a visual acuity less than hand movement had retinal detachment versus only 2 (9 %) patients with visual acuity of hand movement or better (p < 0.01). 6 (66.6 %) of the 9 patients with intraocular foreign bodies had retinal detachment compared to 15 (34.8 %) of the 46 patients without intraocular foreign bodies (p=0.01). Logistic regression analysis confirmed this variables as independent predictors of retinal detachment.

CONCLUSION

We conclude that previous cataract operation, versus less than hand movement and the presence of intraocular foreign bodies are predictive to retinal detachment.

[Selection of subjects: a problem of clinical trials in traumatology. Selection effects and the problem of representation as exemplified by a prospective randomized trial on whiplash injuries]

INTRODUCTION

The internal and external validity of studies is endangered by many factors, such as selection of subjects for inclusion. Selection bias itself is a major problem, but remains unmentioned and probably unexamined in the majority of published clinical trials in traumatology.

AIM OF THE STUDY

The aim of this investigation was to detect effects of subject selection which occurred during our own prospective intervention study. The clinical trial compared subjects with whiplash injury who were either treated by early mobilization or immobilization (soft collar).

MATERIAL AND METHODS

Source population, eligible subjects, study participants and final study participants were compared for differences on various items like age, gender and further sociodemographic as well as crash related factors and clinical findings.

RESULTS

Between 21.08.1997 and 30.04.1999 a total of 732 patients was examined and treated after whiplash in our trauma department. The options for inclusion were met by 453 patients. While 346 escaped from the study, 107 agreed to participate. Of these another 39 patients dropped out of the study. Selection effects were detected on two different levels, leading to distinct statistical procedures from those proposed in the study protocol.

CONCLUSIONS

Uncontrolled selection effects could undermine the interpretability of the results of clinical trials. Awareness of selection effects is mandatory regarding the applicability of these results to subjects, other than those in the group of the final study participants.

Soybean genomic survey: BAC-end sequences near RFLP and SSR markers

We are building a framework physical infrastructure across the soybean genome by using SSR (simple sequence repeat) and RFLP (restriction fragment length polymorphism) markers to identify BACs (bacterial artificial chromosomes) from two soybean BAC libraries. The libraries were prepared from two genotypes, each digested with a different restriction enzyme. The BACs identified by each marker were grouped into contigs. We have obtained BAC- end sequence from BACs within each contig. The sequences were analyzed by the University of Minnesota Center for Computational Genomics and Bioinformatics using BLAST algorithms to search nucleotide and protein databases. The SSR-identified BACs had a higher percentage of significant BLAST hits than did the RFLP-identified BACs. This difference was due to a higher percentage of hits to repetitive-type sequences for the SSR-identified BACs that was offset in part, however, by a somewhat larger proportion of RFLP-identified significant hits with similarity to experimentally defined genes and soybean ESTs (expressed sequence tags). These genes represented a wide range of metabolic functions. In these analyses, only repetitive sequences from SSR-identified contigs appeared to be clustered. The BAC-end sequences also allowed us to identify microsynteny between soybean and the model plants Arabidopsis thaliana and Medicago truncatula. This map-based approach to genome sampling provides a means of assaying soybean genome structure and organization.

Prognostic value of repeated serum CA 125 measurements in first trimester pregnancy

OBJECTIVE

To assess the diagnostic value of maternal CA 125 in patients with symptomatic first trimester pregnancy and to evaluate the prognostic significance of CA 125 versus beta-hCG in early pregnancies with intact fetal heartbeat, complicated by vaginal bleeding.

STUDY DESIGN

Two prospective open-label studies with longitudinal follow-up in the second trial.

SETTING

Academic Department of Obstetrics and Gynecology, University of Cologne.

PATIENTS

Study 1: 168 patients presenting between gestational weeks 6 and 12 with: extrauterine pregnancy, 29; missed abortion, 50; incomplete spontaneous abortion, 38; imminent abortion, 33; and normal pregnancy (no history of endometriosis or ovarian mass), 18. Study 2: Fifty consecutive patients with vaginal bleeding during gestational weeks 6-12 all of whom having demostrable fetal heartbeat. Eighteen patients finally aborted whereas the remainder had normally continuing pregnancy until term.

MAIN OUTCOME MEASURE

Study 1: Single serum determinations of CA 125 and beta-hCG were correlated with the different disorders observed. Study 2: Two sequential measurements of serum CA 125 and beta-hCG performed within a 5-7 days interval were related to the outcome of pregnancy as indicated by changes of the ultrasound presentation, miscarriage, future hospitalization, or delivery.

RESULTS

Study 1: Patients with vaginal bleeding generally had higher median CA 125 values (38 IU/ml; range 1.3-540) compared to non-bleeding patients (17.8 IU/ml; range 1.0-157). No statistically significant differences in regard to median serum CA 125 levels between symptomatic and normal pregnancies occurred: normal pregnancy, 25.5 IU/ml (range 3.2-97); ectopic pregnancy, 26 IU/ml (range 1.3-157); missed abortion, 19.1IU/ml (range 1-242); threatened abortion, 48 IU/ml (range 5.2-540); spontaneous abortion, 40 IU/ml (range 5.4-442). Study 2: Initial CA 125 levels did not differ significantly between both groups of patients with 27/32 non-aborters and 13/18 aborters showing concentrations below 65 IU/ml. After 5-7 days, CA 125 in all patients who eventually aborted remained high or increased whereas non-aborters all had constantly low or steeply declining CA 125 measures. beta-hCG increased in all non-aborters but also in 13/18 aborters during the 5-7 day interval.

CONCLUSION

Single serum measurements of CA 125 in symptomatic first trimester pregnant patients failed to discriminate spontaneous abortion, ectopic or normal pregnancies. However, sequential determinations of maternal CA 125 measurements appear to be a highly sensitive prognostic marker in patients with viable pregnancy at risk for abortion.

Phase III of the migrating motor complex: associated with endogenous xenin plasma peaks and induced by exogenous xenin

Xenin, a recently discovered peptide produced by specific endocrine cells of the duodenal mucosa, has shown exocrine, endocrine and motility effects in the gastroenteropancreatic system in animal experiments. The aim of the present investigation was to study the role of xenin in the regulation of duodenojejunal motility of humans. Twenty-nine healthy volunteers from the hospital staff gave informed consent to participate in this investigation. In 20 volunteers, we determined plasma concentrations of immunoreactive xenin at 15 min intervals over a mean time period of 8 h fasting and recorded the interdigestive motor activity of the duodenojejunum. In a double-blind randomized crossover study on other nine subjects, synthetic xenin in a dose of 4 pmol kg-1 min-1 or placebo was infused for 10 min intravenously in the interdigestive period and postprandially after a liquid meal. Duodenojejunal motility was recorded simultaneously. Predefined interdigestive xenin plasma peaks were found to be significantly associated with the phases III of the migrating motor complex. In the interdigestive period, xenin induced a premature phase III activity in each volunteer; this was followed by a second phase III in five out of nine subjects. In the postprandial state, xenin significantly increased contraction frequency and the percentage of aborally propagated contractions. These findings suggest a role of the peptide hormone xenin in modulating interdigestive and postprandial duodenojejunal motility in humans.

Spatial variation of au coverage as the driving force for nanoscopic pattern formation

Au induced faceting of a 4 degrees vicinal Si(001) surface was studied with chemical resolution using soft x-ray photoemission electron microscopy. For the first time a direct and quantitative determination of the local Au coverage in situ and during deposition was possible. Au atoms, necessary for the expansion of (001) terraces, are accummulated from a lattice gas, resulting in a phase separation between Au enriched terraces and Au depleted step bunches. During a second stage Au also adsorbs on the step bunches and transforms them into (119) facets. A simple Monte Carlo simulation shows that the initial coverage difference between terraces and bunches determines the regularity of the formed mesoscopic grating.

The risk of rupture of the uterus: an analysis of 1086 births after previous caesarean section

In the work presented here, obstetric management after a previous caesarean section was studied in a large patient group at the University Department of Gynecology and Obstetrics in Cologne from 1979 to 1995. Particular attention was given to the feared complication of uterine rupture. From a total of 15 166 deliveries, 1086 of the births had been preceded by one or more caesarean sections. These 1086 births formed the basis for the present study. Vaginal delivery was attempted in 44.5% of patients and was successful in 86% of those cases. Where there had been only one previous caesarean section, the percentage shifted in favor of vaginal delivery. All patients with more than two previous caesarean sections were delivered by elective caesarean section. The feared complication of rupture of the uterus occurred in four cases, for which case reports are presented. In view of such cases, signs of imminent uterus rupture often constitute an indication for elective (11.5%) or emergency resectioning (31.9%). No relationship was found between fetal outcome and mode of delivery. This retrospective study confirms the general recommendation and safety of vaginal delivery after a previous caesarean section as long as risks are minimised by a readiness to proceed with a repeat caesarean when signs of imminent rupture of the uterus arise.

Autofluorescent proteins in single-molecule research: applications to live cell imaging microscopy

The spectral and photophysical characteristics of the autofluorescent proteins were analyzed and compared to flavinoids to test their applicability for single-molecule microscopy in live cells. We compare 1) the number of photons emitted by individual autofluorescent proteins in artificial and in vivo situations, 2) the saturation intensities of the various autofluorescent proteins, and 3) the maximal emitted photons from individual fluorophores in order to specify their use for repetitive imaging and dynamical analysis. It is found that under relevant conditions and for millisecond integration periods, the autofluorescent proteins have photon emission rates of approximately 3000 photons/ms (with the exception of DsRed), saturation intensities from 6 to 50 kW/cm2, and photobleaching yields from 10(-4) to 10(-5). Definition of a detection ratio led to the conclusion that the yellow-fluorescent protein mutant eYFP is superior compared to all the fluorescent proteins for single-molecule studies in vivo. This finding was subsequently used for demonstration of the applicability of eYFP in biophysical research. From tracking the lateral and rotational diffusion of eYFP in artificial material, and when bound to membranes of live cells, eYFP is found to dynamically track the entity to which it is anchored.

Matrix metalloproteinases (MMPs) in fresh human prostate tumour tissue and organ-cultured prostate tissue: levels of collagenolytic and gelatinolytic MMPs are low, variable and different in fresh tissue versus organ-cultured tissue

Prostate tissue was obtained from 22 radical prostatectomies (performed for clinical management of prostate carcinoma) immediately after surgery. A small piece of tissue was fixed immediately in formalin and used for routine histology while a second piece was frozen in OCT and used for immuno-histochemistry. Another small piece was used for isolation of epithelial and stromal cells. The remainder of the tissue was cut into 2 x 2 mm pieces and incubated in organ culture for 8 days. In organ culture, non-malignant, basal epithelial cells underwent a proliferative response. This was accompanied by de-differentiation of glandular structures and by migration of epithelial cells across the surface of the tissue. Erosion of the basement membrane could also be seen in places, but was not widespread. Invasion of epithelial cells into the adjacent stroma was not evident. Production of matrix metalloproteinases (MMPs) with gelatinolytic activity or collagenolytic activity was assessed in organ culture and compared to expression patterns in fresh tissue. MMP-1 (interstitial collagenase) and MMP-9 (92-kDa gelatinase B) were undetectable or low in fresh tissue specimens. Both enzymes were detected in organ culture and both increased over time. Even after 6 days, however, there was only a low level of gelatin-hydrolytic activity and no measurable collagen-hydrolytic activity. In past studies we used organ cultures of normal skin and malignant skin tumours (basal cell carcinomas) to help elucidate the role of collagenolytic and gelatinolytic MMPs in epithelial cell invasion (Varani et al, 2000). Compared to MMP levels observed in skin, levels of these enzymes in prostate are low. The low level of collagenolytic and gelatinolytic MMPs in fresh prostate tissue and in organ-cultured prostate tissue may help explain why there is little tissue destruction in many primary prostate tumours and why the majority of such tumours remain confined to the prostate for extended periods.

Cell cycle regulation of the murine cdc25B promoter: essential role for nuclear factor-Y and a proximal repressor element

Expression of the cdc25B gene is up-regulated late during cell cycle progression (S/G(2)). We have cloned the murine cdc25B promoter to identify elements involved in transcriptional regulation. A detailed structure-function analysis led to the identification of several elements that are located upstream of a canonical Inr motif at the site of transcription initiation and are involved in transcriptional activation and regulation. Activation of the promoter is largely mediated by NF-Y and Sp1/3 interacting with one and four proximal binding sites, respectively. In addition, NF-Y plays an essential role in cell cycle regulation in conjunction with a repressor element (cell cycle-regulated repressor) located approximately 30 nucleotides upstream of the putative Inr element and overlapping a consensus TATA motif. The cell cycle-regulated repressor is unrelated to the previously described cell cycle-regulated repressor elements. Taken together, our observations suggest that expression of the cdc25B gene is controlled through a novel mechanism of cell cycle-regulated transcription.

Structures of bovine glutamate dehydrogenase complexes elucidate the mechanism of purine regulation

Glutamate dehydrogenase is found in all organisms and catalyses the oxidative deamination of l-glutamate to 2-oxoglutarate. However, only animal GDH utilizes both NAD(H) or NADP(H) with comparable efficacy and exhibits a complex pattern of allosteric inhibition by a wide variety of small molecules. The major allosteric inhibitors are GTP and NADH and the two main allosteric activators are ADP and NAD(+). The structures presented here have refined and modified the previous structural model of allosteric regulation inferred from the original boGDH.NADH.GLU.GTP complex. The boGDH.NAD(+).alpha-KG complex structure clearly demonstrates that the second coenzyme-binding site lies directly under the "pivot helix" of the NAD(+) binding domain. In this complex, phosphates are observed to occupy the inhibitory GTP site and may be responsible for the previously observed structural stabilization by polyanions. The boGDH.NADPH.GLU.GTP complex shows the location of the additional phosphate on the active site coenzyme molecule and the GTP molecule bound to the GTP inhibitory site. As expected, since NADPH does not bind well to the second coenzyme site, no evidence of a bound molecule is observed at the second coenzyme site under the pivot helix. Therefore, these results suggest that the inhibitory GTP site is as previously identified. However, ADP, NAD(+), and NADH all bind under the pivot helix, but a second GTP molecule does not. Kinetic analysis of a hyperinsulinism/hyperammonemia mutant strongly suggests that ATP can inhibit the reaction by binding to the GTP site. Finally, the fact that NADH, NAD(+), and ADP all bind to the same site requires a re-analysis of the previous models for NADH inhibition.

Observation of high-energy neutrinos using Cerenkov detectors embedded deep in Antarctic ice

Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by much larger, expandable detectors in, for example, deep water or ice. Here we report the detection of upwardly propagating atmospheric neutrinos by the ice-based Antarctic muon and neutrino detector array (AMANDA). These results establish a technology with which to build a kilometre-scale neutrino observatory necessary for astrophysical observations.

Statistical analysis of single-molecule colocalization assays

In chemical assays, specific molecular recognition events result in close physical proximity of two molecular species, e.g., ligands and receptors. Microscopy techniques that are able to image individual molecules allow for achieving a positional accuracy far beyond the resolution limit Therefore, independent position determination, e.g., by dual-color microscopy, becomes possible, permitting determination of intermolecular distances beyond the resolution limit. Nonzero measured distances occur due to experimental inaccuracies in case of a recognition event or due to accidental close proximity between ligand-receptor pairs. Using general statistical considerations, finite measured distances between single ligand-receptor pairs are directly translated into probabilities for true molecular recognition or mere accidental proximity. This enables a quantitative statistical analysis of single recognition events. It is demonstrated that in a general assay, even in the presence of strong unspecific background, the probability for a certain diagnosis and a measure for its reliability can be extracted from the observation of a few binding events. The power of the method is demonstrated at the example of a single-molecule DNA hybridization assay. Our findings are of major importance for future assay miniaturization and assaying with minute amounts of analyte.