Angular dependence of the Wigner time delay upon tunnel ionization of H2.

When a very strong light field is applied to a molecule an electron can be ejected by tunneling. In order to quantify the time-resolved dynamics of this ionization process, the concept of the Wigner time delay can be used. The properties of this process can depend on the tunneling direction relative to the molecular axis. Here, we show experimental and theoretical data on the Wigner time delay for tunnel ionization of H2 molecules and demonstrate its dependence on the emission direction of the electron with respect to the molecular axis. We find, that the observed changes in the Wigner time delay can be quantitatively explained by elongated/shortened travel paths of the emitted electrons, which occur due to spatial shifts of the electrons' birth positions after tunneling. Our work provides therefore an intuitive perspective towards the Wigner time delay in strong-field ionization.

Deciphering the evolution of Deception Island's magmatic system.

Deception Island (South Shetland Islands) is one of the most active volcanoes in Antarctica, with more than 20 explosive eruptive events registered over the past two centuries. Recent eruptions (1967, 1969, and 1970) and the volcanic unrest episodes that happened in 1992, 1999, and 2014-2015 demonstrate that the occurrence of future volcanic activity is a valid and pressing concern for scientists, technical and logistic personnel, and tourists, that are visiting or working on or near the island. We present a unifying evolutionary model of the magmatic system beneath Deception Island by integrating new petrologic and geochemical results with an exhaustive database of previous studies in the region. Our results reveal the existence of a complex plumbing system composed of several shallow magma chambers (≤10 km depth) fed by magmas raised directly from the mantle, or from a magma accumulation zone located at the crust-mantle boundary (15-20 km depth). Understanding the current state of the island's magmatic system, and its potential evolution in the future, is fundamental to increase the effectiveness of interpreting monitoring data during volcanic unrest periods and hence, for future eruption forecasting.

Potential ash impact from Antarctic volcanoes: Insights from Deception Island's most recent eruption.

Ash emitted during explosive volcanic eruptions may disperse over vast areas of the globe posing a threat to human health and infrastructures and causing significant disruption to air traffic. In Antarctica, at least five volcanoes have reported historic activity. However, no attention has been paid to the potential socio-economic and environmental consequences of an ash-forming eruption occurring at high southern latitudes. This work shows how ash from Antarctic volcanoes may pose a higher threat than previously believed. As a case study, we evaluate the potential impacts of ash for a given eruption scenario from Deception Island, one of the most active volcanoes in Antarctica. Numerical simulations using the novel MMB-MONARCH-ASH model demonstrate that volcanic ash emitted from Antarctic volcanoes could potentially encircle the globe, leading to significant consequences for global aviation safety. Results obtained recall the need for performing proper hazard assessment on Antarctic volcanoes, and are crucial for understanding the patterns of ash distribution at high southern latitudes with strong implications for tephrostratigraphy, which is pivotal to synchronize palaeoclimatic records.

Early postoperative oral fluid intake in paediatric day case surgery influences the need for opioids and postoperative vomiting: a controlled randomized trial†.

Background: In children younger than 4 yr, it is difficult to distinguish the cause of postoperative distress, such as thirst, pain, and emergence delirium. This may lead to inappropriate treatment, such as administration of opioids. The aim of this study was to evaluate the influence of early postoperative oral fluid intake on the use of opioid analgesics and the incidence of postoperative vomiting (POV) after paediatric day case surgery. Methods: After ethics committee approval and with parental informed consent, planned day surgery patients aged 6 months to 4 yr were randomized to the liberal group (LG), in which apple juice (10 ml kg−1) was offered first if the Face Legs Activity Cry COnsolability (FLACC) score was ≥4 in the PACU, or to the control group (CG), in which children were treated after surgery according to the institutional opioid protocol, and drinking was allowed only upon the return to the ward. Bayesian statistical analysis was used to compare POV incidence and opioid use across groups. Results: Data from 231 patients were analysed. The incidence of POV in the LG and the CG was 11.40 and 23.93%, respectively. An opioid was needed in 14.04% (mean total dose: 0.18 mg kg−1) and 35.89% (mean total dose: 0.20 mg kg−1) of the patients in the LG and the CG. The PACU stay was 53.45 and 65.05 min in the LG and the CG, respectively (all differences were statistically significant). Conclusions: In our paediatric outpatient setting, early postoperative oral fluid intake was associated with a reduction in opioid use and POV incidence. These results deserve confirmation in other settings. Clinical trial registration: NCT02288650.

Stress barriers controlling lateral migration of magma revealed by seismic tomography.

Understanding how monogenetic volcanic systems work requires full comprehension of the local and regional stresses that govern magma migration inside them and why/how they seem to change from one eruption to another. During the 2011-2012 El Hierro eruption (Canary Islands) the characteristics of unrest, including a continuous change in the location of seismicity, made the location of the future vent unpredictable, so short term hazard assessment was highly imprecise. A 3D P-wave velocity model is obtained using arrival times of the earthquakes occurred during that pre-eruptive unrest and several latter post-eruptive seismic crises not related to further eruptions. This model reveals the rheological and structural complexity of the interior of El Hierro volcanic island. It shows a number of stress barriers corresponding to regional tectonic structures and blocked pathways from previous eruptions, which controlled ascent and lateral migration of magma and, together with the existence of N-S regional compression, reduced its options to find a suitable path to reach the surface and erupt.

Histopathologic examination of the genital tract in rabbits treated once or twice with a slow-release deslorelin implant for reversible suppression of ovarian function.

A total of 13 rabbits were treated with a subcutaneous deslorelin long-term release implant (4.7 mg) to study the effect on ovarian function and histologic features of the uterus. Seven rabbits (group 1) were implanted with a slow-release deslorelin implant before onset of puberty for 273 days as a part of a previous study. After resumption of ovarian function had been confirmed, they were implanted again at the age of 430 days. Six adult rabbits (>177 days old; group 2) were implanted with a slow-release deslorelin implant for 273 days. Ovarian function before, during, and after treatment with the implant was assessed by measuring serum progesterone levels 10 days after a challenge injection of a short-acting GnRH (0.8 µg buserelin intramuscularly) on progesterone levels in peripheral blood. Values more than 4 ng/mL progesterone were considered to verify ovarian function. Animals in group 1 underwent ovariohysterectomy during the second treatment with the implant and the uteri, and ovaries were subjected to histopathologic examination. Endometrial hyperplasia and endometritis were observed in 5 of 7 animals. Nonatretic and atretic follicles at different developmental stages, but no active corpora lutea, were present in the ovaries. Ovariohysterectomy of group 2 animals was performed 2 to 12 months after implant removal. The histopathologic examination of the uterus and ovary of four animals neutered during induced pseudopregnancy showed no signs of uterine disorders. In two animals undergoing ovariohysterectomy 12 months after implant removal, endometritis was present. Their ovaries contained follicles at different developmental stages and corpora albicantia. Reversible suppression of ovarian function can be achieved in female rabbits by the use of GnRH slow-release implants administered before or after puberty. The findings of endometrial hyperplasia and endometritis in seven out of 13 rabbits treated once or twice with the implant may indicate that the development of age-related pathologies of the uterus cannot be prevented by the suppression of ovarian function with a long-acting GnRH implant.

Sperm membrane integrity in fresh and frozen-thawed canine semen samples: a comparison of vital stains with the NucleoCounter SP-100.

The objective of this study was to assess sperm membrane integrity in canine semen samples using three different vital stains and the NucleoCounter SP-100 (NC). In addition, the occurrence of half-stained sperm heads, the influence of investigator, and storage-related artifacts using stained smears were examined. Forty fresh (30 dogs) and 40 frozen-thawed (28 dogs) canine semen samples were analyzed. The vital stains eosin (E), eosin-nigrosin (EN), and bromphenolblue-nigrosin (BN) were compared. Two smears per stain were prepared and a total of 200 sperm per slide were classified using bright field microscopy. Each slide was examined twice by three investigators. Spermatozoa with completely red (E, EN) or blue (BN) stained sperm heads were classified as "dead". Half-stained sperm heads were counted separately. Sperm concentration and viability were determined using the NC. The NC works with a built-in fluorescence microscope using propidium iodide as a fluorescence dye. Statistical analysis for comparison of results was made using mean values with standard deviation, Bland-Altman plot and coefficient of variation (CV). Staining with E led to a significant higher percentage of dead sperm compared with EN and BN (P < 0.05), which gave comparable results. Vital stains revealed higher CVs (range 8.8%-32.1%) than the NC (<6.5%). Interobserver viability ranged from 17.5% to 45.4% and was within the same range between stains. If only completely stained sperm heads were considered, best agreement was found between the E and the NC. In case of EN and BN, inclusion of half-stained sperm heads reduced the difference compared with NC. In general, the agreement between methods was better in samples with a low percentage of dead spermatozoa. In smears of fresh semen stored up to 3 months, no increase in the percentage of dead spermatozoa could be observed. In some smears of frozen-thawed samples stained with E (n = 12) or BN (n = 2), all previously unstained spermatozoa were additionally stained during storage. In conclusion, all vital stains examined in this study technically can be used for differentiation between live and dead spermatozoa in canine semen samples, but the relatively high CVs have to be kept in mind. It is recommended to examine smears of frozen-thawed semen soon after preparation. Half-stained sperm heads should be counted as live sperm in E-stained smears. The NC allows assessment of sperm concentration and viability with a reasonable repeatability.

Reversible estrous cycle suppression in prepubertal female rabbits treated with slow-release deslorelin implants.

The aim of this study was to examine the long-term effect of a 4.7-mg deslorelin GnRH analog implant on ovarian function in the prepubertal female rabbit. Seven female rabbits (group 1) were treated with the implant at the age of 60 days. The implant was inserted subcutaneously in the umbilical region. Two animals (group 2) were not treated and served as a control group. The vulva of all 9 animals was examined for the presence of typical cyclical changes, additionally the occurrence of mounting behavior was recorded. Ovarian function was checked by administration of a short-acting GnRH agonist to induce ovulation and pseudopregnancy (0.8 µg of buserelin per animal intramuscularly). Ten days after each treatment with buserelin, blood was collected for progesterone measurement to confirm pseudopregnancy. After implant insertion, the first blood collection (Day 10) was done without preceding induction of ovulation to screen for implant induced ovulation and pseudopregnancy. The implant was in situ for 273 days, and during this time span, 12 attempts of induction of ovulation were carried out in intervals of 21 days, beginning at the age of 81 days. Afterward, it was removed under local anesthesia and 3 further inductions of ovulation by the same scheme were conducted. The insertion of the implant led to the establishment of a pseudopregnancy in 2 of 7 animals; the remaining 5 animals did not show elevated progesterone values. Attempts to induce ovulation by administration of the short-acting GnRH analog while the slow-release GnRH analog implant was in place were not successful in treated animals, and progesterone concentrations were basal. The effect was reversible as ovulation could be induced in 2 subsequent cycles in all animals by the third induction of ovulation after implant removal. Induction of ovulation in control animals at the age of 110 and 131 days resulted in elevated progesterone levels after 10 days. No adverse side effects could be observed in implant-treated animals. The typical red coloration of the vulva could be seen in group 2 and after implant removal in group 1. The results suggest that in 5 of 7 rabbits, puberty was delayed by the treatment with the 4.7-mg deslorelin slow-release analog until the implant had been removed. In the other animals, the treatment induced an initial flare-up phenomenon. Afterward, the treatment could reversibly suppress ovarian function in all 7 treated animals.

On the wave length of smooth periodic traveling waves of the Camassa-Holm equation.

This paper is concerned with the wave length λ of smooth periodic traveling wave solutions of the Camassa-Holm equation. The set of these solutions can be parametrized using the wave height a (or "peak-to-peak amplitude"). Our main result establishes monotonicity properties of the map [Formula: see text], i.e., the wave length as a function of the wave height. We obtain the explicit bifurcation values, in terms of the parameters associated with the equation, which distinguish between the two possible qualitative behaviors of [Formula: see text], namely monotonicity and unimodality. The key point is to relate [Formula: see text] to the period function of a planar differential system with a quadratic-like first integral, and to apply a criterion which bounds the number of critical periods for this type of systems.

[Treatment of nausea and vomiting with 5HT3 receptor antagonists, steroids, antihistamines, anticholinergics, somatostatinantagonists, benzodiazepines and cannabinoids in palliative care patients : a systematic review]. / Behandlung von übelkeit und erbrechen mit 5HT3-antagonisten, steroiden, antihistaminika, anticholinergika, somatostatinanaloga, benzodiazepinen und cannabinoiden bei palliativpatienten : ein systematisches review.

BACKGROUND: Various recommendations exist for the treatment of nausea and vomiting in palliative care but only few studies and even less systematic reviews look into antiemetic therapy for patients receiving palliative care. OBJECTIVES: This systematic review aims to analyze the current evidence for antiemetic treatment with 5HT3 receptor antagonists, steroids, antihistamines, anticholinergics, somatostatin analogs, benzodiazepines and cannabinoids in palliative care patients with far advanced cancer not receiving chemotherapy or radiotherapy, acquired immune deficiency syndrome (AIDS), chronic obstructive pulmonary disease (COPD), progressive heart failure, amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS). Results regarding evidence of treatment with prokinetic and neuroleptic agents will be published separately. METHODS: The electronic databases PubMed and EmBase were systematically searched for studies (published 1966-2011) dealing with antiemetic therapy in palliative care and electronic retrieval was completed by manual searching. Studies with patients undergoing chemotherapy or radiotherapy, pediatric studies and studies published in languages other than English or German were excluded. Studies addressing therapy with 5HT3 receptor antagonists, steroids, antihistamines, anticholinergics, somatostatin analogs, benzodiazepines or cannabinoids were identified and selected for this systematic review. RESULTS: In the general search 75 relevant studies were found. Of those 36 addressed 5HT3 receptor antagonists, steroids, antihistamines, anticholinergics, somatostatin analogs, benzodiazepines and cannabinoids, 13 considered 5HT3 receptor antagonists, 10 somatostatin antagonists, 9 steroids, 5 cannabinoids, 4 anticholinergics, 1 antihistamines and none benzodiazepines. Furthermore six systematic reviews exist. Evidence for any drug used as an antiemetic is low. Concerning 5HT3 receptor antagonists data are insufficient for recommendations on the treatment of patients with AIDS and MS due to the small size of included patient groups. For patients with cancer contradictory results were published: the larger studies showed a positive effect of 5HT3 receptor antagonists and better efficacy, as compared to metoclopramide, dexamethasone and neuroleptics. Heterogeneous results were found for steroids, with a positive trend for patients with cancer. Data are insufficient for antihistamines. Studies prove effectiveness of butylscopolammonium in the treatment of nausea and vomiting caused by malignant gastrointestinal obstruction, whereas octreotide is superior to butylscopolammonium. Regarding benzodiazepines for symptom control of nausea and vomiting in palliative care patients no studies were detected. Cannabinoids were found to relieve nausea and vomiting in patients with cancer and AIDS but with notable side effects. Furthermore, the studies compared cannabinoids to less recent antiemetic drugs but not, for example to 5HT3 receptor antagonists. Regarding symptom control of nausea and vomiting in patients with COPD, progressive heart failure and ALS no studies were undertaken in patients receiving palliative care. CONCLUSIONS: In palliative care patients with nausea and vomiting 5HT3 receptor antagonists can be used if treatment with other antiemetics, such as metoclopramide and neuroleptics is not sufficient. There is a trend that steroids in combination with other antiemetics improve symptom relief. Cannabinoids rather have a status as a second line antiemetic. In cases of nausea and vomiting caused by malignant gastrointestinal obstruction octreotide showed the best and butylscopolammonium bromide the second best results. Concerning antihistamines and benzodiazepines insufficient data was found. Recommendations in the literature are mainly based on studies in patients with cancer. The overall strength of evidence is low. More well designed studies in palliative care patients are needed in order to provide evidence-based therapy. The English full text version of this article will be available in SpringerLink as of November 2012 (under "Supplemental").

[Treatment of nausea and vomiting with prokinetics and neuroleptics in palliative care patients : a review]. / Behandlung von übelkeit und erbrechen mit prokinetika und neuroleptika bei palliativpatienten : ein review.

BACKGROUND: Many recommendations concerning the treatment of nausea and vomiting in palliative care patients exist but what is the evidence for this? Most studies dealing with this topic have focused on cancer patients under chemotherapy and/or radiation therapy or on patients with postoperative nausea. Cancer patients without chemotherapy or radiation therapy, patients without postoperative nausea, and patients having other diseases with palliative care aspects, such as acquired immunodeficiency syndrome (AIDS), chronic obstructive pulmonary disease (COPD), progressive heart failure, amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS) have been underrepresented in studies on nausea and vomiting so far. OBJECTIVES: The aim of this review was to determine the level of evidence for the treatment of nausea and vomiting with prokinetics and neuroleptics in palliative care patients suffering from far advanced cancer and no longer being treated with chemotherapy or radiation therapy, AIDS, COPD, progressive heart failure, ALS or MS. METHODS: Two different electronic databases (PubMed und Embase) were used to identify studies. Furthermore, a hand search for related articles was performed. No restriction was made concerning study types. Studies with patients undergoing chemotherapy radiation therapy or suffering from postoperative nausea, pediatric studies and studies published neither in English nor in German were excluded. RESULTS: A total of 30 studies fulfilling the inclusion criteria were found. All studies focused on cancer patients. Despite intensive research studies in patients with AIDS, COPD, heart failure, ALS or MS were not detected. Metoclopramide is seen as an effective drug in many studies whereas the evidence for it is moderate at best. Within the group of neuroleptics, levosupiride and levomepromazine seem to have good antiemetic potential but the evidence level is low. CONCLUSION: In patients with advanced cancer not being treated with chemotherapy or radiation therapy, metoclopramide can be used to reduce nausea and vomiting. Neuroleptics, such as levosulpiride or levomepromazine are alternatives but their adverse effects have to be considered carefully. The evidence level for prokinetics and neuroleptics is moderate to low. Concerning palliative care of patients with diseases other than cancer no studies exist. More well designed studies in palliative care patients are needed in order to facilitate evidence based antiemetic therapy. The English full text version of this article will be available in SpringerLink as of November 2012 (under "Supplemental").

Current therapeutic strategies in cardiorenal syndrome.

Cardiorenal syndromes (CRS) are disorders of the heart and kidneys in which an acute or chronic dysfunction in one organ may induce acute or chronic dysfunction of the other. Primary disorders of one of these two organs often result in secondary dysfunction or injury of the other. The lack of specific trials in this field highlights the need for further studies aimed to assess titration and appropriate dosages of drugs, according to both the etiology of chronic heart failure (CHF) and also the severity of underlying renal dysfunction. Moreover, the most recent clinical trials evaluating clinical and renal outcome in acute heart failure syndromes (AHFS), failed to demonstrate an improvement in renal function and perfusion. Therefore, Current American and European Guidelines for AHFS does not provide specific recommendation for patients with renal impairment. In this scenario several questions regarding the drugs, their recommended dosage and potential adverse effects on cardiac and renal outcome need to be addressed. Subsequently, therapy inducing an improvement in the renal function, a reduction of neurohormonal activation and an improvement of renal blood flow, could lead to a reduction in mortality and hospitalization in patients with CRS.

SU-E-I-44: The UF/NCI Family of Hybrid Computational Phantoms Representing the Current US Population of Male and Female Children and Adolescents Applications to CT Organ Dosimetry.

PURPOSE: To assist in the rapid reporting of patient organ doses, researchers at the University of Florida and the National Cancer Institute have developed a family of computational hybrid phantoms, constructed from NURBS and polygon mesh surfaces, that fully represent the ICRP 89 50th percentile reference newborn, 1-year-old, 5-year-old, 10-year-old, 15-year- old male and female, and adult male and female. Coupled with Monte Carlo simulations, these phantoms can be used to estimate patient organ doses. Substantial increases seen in childhood obesity in the United States have prompted us to undergo a major revision to the UF/NCI phantom library. METHODS: A decision was made to construct the new library in a gridded fashion by height/weight without further reference to age-dependent weight/height percentiles. At each height/weight combination, secondary circumferential parameters are also defined and used for phantom construction. All morphometric data for the new library are taken from the CDC NHANES survey data over the time period 1999 to 2006, the most recent reported survey period. A subset of the phantom library was then used in a CT organ dose sensitivity study to examine the degree to which full Monte Carlo simulations would be required to track organ doses for patients that are severely underweight to obese in body size. RESULTS: Using primary and secondary parameters, a grid containing 85 pediatric male height/weight bins and a grid containing 73 pediatric female height' weight bins were constructed. These grids will provide the blueprints for later constructing a comprehensive library of patient' dependent phantoms containing 158 pediatric phantoms. CONCLUSIONS: In the future, the UF/NCI phantom library will be used to construct pre-computed dose libraries for individuals undergoing CT examinations. Ultimately, these libraries can be deployed in the clinic for electronic recording of patient organ dosimetry following diagnostic imaging procedures.

The use of letter communication for patients enrolled in a pharmacist managed anticoagulation clinic.

WHAT IS KNOWN AND OBJECTIVE: It is unknown how letter communication vs. telephone communication compares in terms of affecting outcomes in patients followed in a busy anticoagulation clinic. This study was performed to determine if sending letters to communicate laboratory results and future appointments with patients enrolled in a pharmacy managed anticoagulation clinic is an effective alternative to telephone communication. METHODS: A retrospective review of quality assurance data currently collected at our facility was performed. Data were analyzed 4 months before and 4 months after the implementation of the letter notification. Data on percent international normalized ratio (INR) in therapeutic range, missed laboratory draw frequency and major bleeding events were collected daily, compiled monthly and then compared between the telephone and letter groups. RESULTS: There was no statistical difference in the percentage of INRs that were within goal range before and after letter initiation. There was a slight increase in the percentage of INR laboratory draws that were missed after the implementation of the letters (23% vs. 26%, P = 0·002). There were more major bleeding events after letter initiation, but this did not reach statistical significance. Approximately 80% of the patients received letters as the method of communication in the letter group. WHAT IS NEW AND CONCLUSION: The use of letters to notify warfarin patients with laboratory results is an effective method of communication without adversely affecting patient outcomes.

A first report on the characterization of rotavirus strains in Sierra Leone.

In an effort to reduce the high mortalities associated with rotavirus infections, a number of African countries are considering introducing human rotavirus vaccines. The demonstrated safety and efficacy of the live-attenuate human rotavirus vaccines in several clinical trials worldwide has accelerated such initiatives. Although the percentage-mortality rates for Sierra Leone are top of the list for rotavirus-associated deaths in Africa, no study has reported the prevalent strains circulating within this country. In this study, stool specimens were collected from 128 Sierra Leonean children presenting with diarrhea in 2005. Almost 37.5% (48/128) were rotavirus positive by EIA, of which 89.6% (43/48) revealed a short electropherotype, and a further 6.98% (3/48) could not be assigned a PAGE pattern. Genotyping analysis revealed G2P[4] (30.23%), G2P[6] (13.95%), G8P[6] (11.63%), G2P[8] (4.65%), G8P[4] (4.65%), and G8P[8] (2%) strains. About 11% were only assigned VP7 genotypes (G2), while 20.9% had mixed G and P types. The frequent detection of G2 rotaviruses could be of concern considering data generated from some studies that suggests lower efficacy of Rotarix® vaccine against G2 rotaviruses. This underscores the need for extensive and continuous regional strain surveillance to support rotavirus vaccines introduction and guide future vaccine development efforts. Such information will be useful before considering administration of specific rotavirus vaccine candidates in countries like Sierra Leone where little is known about circulating rotavirus strains.

Genomic characterization of human rotavirus G10 strains from the African Rotavirus Network: relationship to animal rotaviruses.

Global rotavirus surveillance has led to the detection of many unusual human rotavirus (HRV) genotypes. The aim of this study was to elucidate the genetic and evolutionary relationships of short fragments of all 11 gene segments of G10 HRV strains identified in West Africa through the African Rotavirus Network (ARN) system. During 1998-2004 surveillance within the ARN, we identified 5 G10 P[8] HRV strains. Fragments of all 11 gene segments of these G10 strains were sequenced. Phylogenetic and sequence analyses of each gene segment revealed high nucleotide similarities amongst the ARN strains (97-100%) except in the case of the VP1(85-96%) and NSP2 genes (87.8-99.7%) where some strains were divergent. All genes of the ARN strains were classified as Wa-like (genotype 1) with the exception of their VP7 gene of all strains (genotype G10) and the VP6 gene of a single strain, 6755/2002/ARN (DS-1 like, genotype 2). While classified as Wa-like, the NSP2 genes of four of the ARN strains occupied a distinct sub-lineage related to simian strain Tuch, while the NSP2 of strain 6755/2002/ARN and NSP5 genes of all strains were closely related to the cognate genes of both human and animal strains belonging to the Wa-like genogroup. Although these findings help to elucidate the evolution of ARN G10 strains, additional sequence studies of cognate animal rotavirus genes are needed to determine irrefutably the specific origin of those genes relative to both human and animal rotavirus strains.

Characterization and molecular epidemiology of rotavirus strains recovered in Northern Pretoria, South Africa during 2003-2006.

Rotavirus infection is the most common cause of severe dehydrating gastroenteritis in infants and young children and remains a significant clinical problem worldwide. The severity and the burden of rotavirus disease could be reduced through the implementation of an effective vaccine. The aim of this study was to characterize rotavirus strains circulating in the local community as part of an ongoing hospital burden of disease study when a G1P[8] rotavirus vaccine candidate was being evaluated in the same community. From 2003 through 2006, 729 rotavirus-positive stool specimens were collected from children <5 years of age who were treated for diarrhea at Dr George Mukhari Hospital, Ga-Rankuwa, South Africa. Molecular characterization of the strains was performed by polyacrylamide gel electrophoresis and genotyping of the VP4 and VP7 alleles using well-established seminested multiplex reverse-transcription polymerase chain reaction methods. In 2003, 62% of strains exhibited the short rotavirus electropherotype, and the most common rotavirus strain was G2P[4]. In subsequent years, predominant rotavirus strains included G1P[8] and G1P[6] in 2004, G3P[8] and G3P[6] in 2005, and G1P[8] in 2006. For the 4 years of the study, rotavirus strains with P[6] genotype were detected in 25% of all rotavirus-positive specimens. In addition, unusual G12P[6] and G8 strains were detected at a low frequency. These results reflect the diversity of rotavirus strains circulating in South African communities.

Genomic characterization of human rotavirus G8 strains from the African rotavirus network: relationship to animal rotaviruses.

Global rotavirus surveillance has led to the detection of many unusual human rotavirus (HRV) genotypes. During 1996-2004 surveillance within the African Rotavirus Network (ARN), six P[8],G8 and two P[6],G8 human rotavirus strains were identified. Gene fragments (RT-PCR amplicons) of all 11-gene segments of these G8 strains were sequenced in order to elucidate their genetic and evolutionary relationships. Phylogenetic and sequence analyses of each gene segment revealed high similarities (88-100% nt and 91-100% aa) for all segments except for gene 4 encoding VP4 proteins P[8] and P[6]. For most strains, almost all of the genes of the ARN strains other than neutralizing antigens are related to typical human strains of Wa genogroup. The VP7, NSP2, and NSP5 genes were closely related to cognate genes of animal strains (83-99% and 97-99% aa identity). This study suggests that the ARN G8 strains might have arisen through VP7 or VP4 gene reassortment events since most of the other gene segments resemble those of common human rotaviruses. However, VP7, NSP2 (likely), and NSP5 (likely) genes are derived potentially from animals consistent with a zoonotic introduction. Although these findings help elucidate rotavirus evolution, sequence studies of cognate animal rotavirus genes are needed to conclusively determine the specific origin of those genes relative to both human and animal rotavirus strains.

Role of astrovirus in intussusception in Nigerian infants.

Intussusception (IS) is a form of intestinal obstruction in which a segment of the bowel prolapses into a more distal segment. Viral infections, mostly adenovirus, enteroviruses, human herpesvirus and Epstein-Barr virus are reported in 20-50% of childhood cases of IS. Between January and July 2004, six stool specimens collected from infants 0- to 8-months old diagnosed and admitted for IS were investigated for the presence of rotavirus, astrovirus and adenovirus antigens. Astrovirus antigen was detected in three of the six stool specimens by enzyme immune assay (EIA) and confirmed in two specimens by reverse transcription-polymerase chain reaction (RT-PCR). Rotavirus, non-enteric adenovirus and astrovirus were detected by EIA, as mixed infections in a single specimen. The rotavirus strain revealed a SGI+II, mixed G1G2G8P[6] genotype and had no visible electrophoretic profile. A larger study is needed to determine the extent of involvement of astroviruses in IS in infants and the virus should be included in studies investigating the aetiology of IS.