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At least 19 recordsLinked to original sources
PubMed2001

Phylogenetic analysis of hop and grapevine isolates of hop stunt viroid supports a grapevine origin for hop stunt disease.

We have examined sequence variability among nine isolates of hop stunt viroid (HSVd) collected from hop gardens in Tohoku district in Japan, the only area in the world where hop stunt disease is endemic. Six different consensus and one-consensus sequences as well as 12 sequence variants were detected in the nine HSVd-hop isolates, which suggested the sequence of HSVd-hop was remarkably variable. A neighbor-joining analysis was carried out on the new HSVd-hop sequences together with 44 previously described variants of HSVd isolated from hop and other species. All the HSVd-hop sequences recovered from hops cultivated in the Tohoku district of Japan as well as the type isolate and two Korean isolates form a cluster with the HSVd-g subtype 1 commonly recovered from grapevine. This close relationship between HSVd-hop and -grapevine isolates strongly supports the grapevine origin for hop stunt disease.

Base Sequence↗
PubMed2006

Improving the sensitivity of the hop index in patients with an ACL deficient knee by transforming the hop distance scores.

BACKGROUND: The one leg hop for distance is one of the most commonly employed functional tests utilized in the evaluation of the ACL deficient and reconstructed patient. While the reliability of the hop test scores has been well established, validity studies have revealed low sensitivity rates in detecting functional limitations using the hop index (the ratio or percentage of limb performance). However, the impact of the inherent limitations associated with the hop index have not been investigated to date. One specific limitation relates to the impact of the differences in the underlying hop distance scores. Therefore, this pilot study set out to determine: 1) the impact that between limb differences in hop distance has on the sensitivity of the hop index in detecting functional limitations and; 2) whether a logarithmic transformation of the underlying hop distance scores improves the sensitivity of the hop index. METHODS: A cross sectional design involving the evaluation of one leg hop for distance performance in a consecutive sample of 10 ACL deficient males with an isolated ACL tear awaiting reconstructive surgery and nine gender, age-matched controls. RESULTS: In the ACL deficient, the hop index was associated with the distance hopped on the non-injured limb (r = -0.66, p = 0.04) but not on the injured limb. Transformation (logarithmic) of the hop distance scores and re-calculation of the hop index using the transformed scores increased the sensitivity of the hop index in the detection of functional limitations from 20 to 60% and 50 to 70% using the normal limb symmetry reference norms of > or = 85% and 90% respectively. CONCLUSION: The distance hopped on the non-injured limb is a critical factor in detecting functional limitations using the hop index in patients with an ACL deficient knee. Logarithmic transformation of the hop distance scores minimizes the effect of the arithmetic differences between limbs however; the sensitivity of the hop index in detecting abnormal limb symmetry remains low.

Adult↗
PubMed2006

Characterization of a highly hop-resistant Lactobacillus brevis strain lacking hop transport.

Resistance to hops is a prerequisite for lactic acid bacteria to spoil beer. In this study we analyzed mechanisms of hop resistance of Lactobacillus brevis at the metabolism, membrane physiology, and cell wall composition levels. The beer-spoiling organism L. brevis TMW 1.465 was adapted to high concentrations of hop compounds and compared to a nonadapted strain. Upon adaptation to hops the metabolism changed to minimize ethanol stress. Fructose was used predominantly as a carbon source by the nonadapted strain but served as an electron acceptor upon adaptation to hops, with concomitant formation of acetate instead of ethanol. Furthermore, hop adaptation resulted in higher levels of lipoteichoic acids (LTA) incorporated into the cell wall and altered composition and fluidity of the cytoplasmic membrane. The putative transport protein HitA and enzymes of the arginine deiminase pathway were overexpressed upon hop adaptation. HorA was not expressed, and the transport of hop compounds from the membrane to the extracellular space did not account for increased resistance to hops upon adaptation. Accordingly, hop resistance is a multifactorial dynamic property, which can develop during adaptation. During hop adaptation, arginine catabolism contributes to energy and generation of the proton motive force until a small fraction of the population has established structural improvements. This acquired hop resistance is energy independent and involves an altered cell wall composition. LTA shields the organism from accompanying stresses and provides a reservoir of divalent cations, which are otherwise scarce as a result of their complexation by hop acids. Some of the mechanisms involved in hop resistance overlap with mechanisms of pH resistance and ethanol tolerance and as a result enable beer spoilage by L. brevis.

Adaptation, Physiological↗
PubMed2003

Monitoring of insecticide resistance in damson hop aphid, Phorodon humuli Schrank (Hemiptera: Aphididae) from German hop gardens.

The damson hop aphid, Phorodon humuli (Schrank) (Hemiptera: Aphididae), is one of the most important sucking pests of many hop-growing areas world-wide. In this study we determined the efficacy of several insecticides against strains collected throughout the year 2001. All strains were collected in different hop gardens in the Hallertau (Bavaria), Germany, the largest hop-growing area of the world. First of all we established a leaf dip bioassay, carried out using six-well tissue culture plates and appropriate for monitoring susceptibility against imidacloprid, oxydemeton-methyl, cyfluthrin, amitraz, pymetrozine and pirimicarb. Four of these compounds, imidacloprid, cyfluthrin, pymetrozine and amitraz, are currently registered for the control of sucking pests in German hop gardens and are useful against P. humuli. The leaf-dip bioassay system turned out to be very reliable and robust. Ten P. humuli strains were collected in May 2001 and maintained in the laboratory to assess their resistance to the different insecticides in comparison with two laboratory reference strains (H2 and H5). Using diagnostic concentrations, resistance monitoring for imidacloprid and cyfluthrin was investigated during July and August 2001 on 53 populations from 30 sites around the Hallertau, an area of ca 2500 km2. Resistance to diagnostic concentrations (LC95 for reference strains) of imidacloprid, amitraz and pymetrozine was not detected in any strain received in 2001, but late-season (August) populations seemed to respond more heterogeneously than those collected mid-season (July). Overall composite mean mortalities to diagnostic concentrations of imidacloprid (13 mg litre(-1)) in collections from May, July and August were 95 (+/-2.5), 98 (+/-2.3) and 87 (+/-5.9)%, respectively. Moderate resistance to pyrethroids was observed in all strains collected in May and August using a diagnostic concentrations of 10 mg litre(-1) cyfluthrin (LC95 of the susceptible reference strain H5). Slight to moderate resistance to diagnostic concentrations of oxydemeton-methyl and pirimicarb was observed in some, but not all, strains collected early season. The results are discussed in terms of the implemention of hop aphid resistance management strategies in German hop-cultivation areas.

Animals↗
PubMedDate not supplied

Analysis of pesticide residues in hops and their extraction by liquid CO2 during the production of hop extracts.

A method has been developed for analysing pesticide residues in whole hops, hop pellets and hop extracts by GC-MS. Five batches of hop pellets containing nine different pesticides (triadimefon, dicofol, mephosfolan, bupirimate, cyhalothrin, tetradifon, endosulfan, pyrazophos and total bisdithiocarbamates) were extracted with liquid CO2. Pesticide concentrations in the original hop pellets and the extracts were determined. The pesticides were concentrated by the extraction process (concentration factor 1.3-8.3), except for the bisdithiocarbamates, which were not extracted. When the same amount of bitterness was added into the brewing process using liquid CO2 extract as opposed to hop pellets, for most of the pesticides proportionately less pesticide was added. However, for two pesticides (dicofol and triadimefon) corrected residue levels were similar to, or in some cases slightly higher than, those in hop pellets.

Beer↗
PubMed1998

Changes in the excitability of soleus muscle short latency stretch reflexes during human hopping after 4 weeks of hopping training.

Changes in the excitability of the human triceps surae muscle short latency stretch reflexes were investigated in six male subjects before and after 4 weeks of progressive two-legged hopping training. During the measurements the subjects performed 2-Hz hopping with: preferred contact time (PCT) and short contact time. The following reflex parameters were examined before and after the training period: the soleus muscle (SOL) Hoffmann-reflex (H-reflex) at rest and during hopping, the short latency electromyogram (EMG) components of the movement induced stretch reflex (MSR) in SOL and medial gastrocnemius muscle (MG), and the EMG amplitude of the SOL and MG tendon reflexes (T-reflexes) elicited at rest. The main results can be summarized as follows: the SOL T-reflex had increased by about 28% (P < 0.05) after training while the MG T-reflex was unchanged; the SOL MSR (always evident) and the MG MSR (when observable) did not change in amplitude with training, and before training the SOL H-reflex in both hopping situations was significantly depressed to about 40% of the reference value at standing rest (P < 0.05). After training the H-reflex during PCT hopping was no longer depressed. As the value of the measured mechanical parameters (the total work rate, joint angular velocity and the ankle joint work rate) was unchanged after training in both hopping situations, the reflex changes observed could not be ascribed to changes in the movement pattern. To explain the observed changes, hypotheses of changes in the excitability of the stretch reflex caused by the training were taken into consideration and discussed.

Adult↗
PubMed1976

A technique for the differential isolation of hop mosaic virus and hop latent virus.

Two rod-shaped viruses of similar length occurring in hops were isolated from a mixed infection. One (hop mosaic virus) infected Nicotiana clevelandii, produced mosaic symptoms in mosaic-sensitive hop cultivars, and did not infect Chenopodium murale. The other (hop latent virus) infected C. murale but not N. clevelandii and did not produce mosaic symptoms in hops. Neither N. clevelandii nor C. murale developed distinct symptoms after infection with the respective virus. Both viruses produced a systemic chlorotic flecking in Cluster hop seedling clones.

Methods↗
PubMed2001

Anthropometric and demographic factors affecting distance hopped and limb symmetry index for the crossover hop-for-distance test in high school athletes.

STUDY DESIGN: Prospective cohort study using a random selection from an accessible population. OBJECTIVES: We examined anthropometric and demographic characteristics affecting distance hopped (DH) and limb symmetry index (LSI) in the crossover hop-for-distance test in uninjured high school athletes. BACKGROUND: Between-subject comparisons of hop test results described by DH and LSI are common in the literature and clinical practice. The effect that anthropometric traits and demographic characteristics have on these measures is uncertain but must be known to correctly interpret hop-for-distance test results in research or to determine suitability of return to sports. METHODS AND MEASURES: For 201 high school athletes (age = 15.15+/-1.45 years, mean weight = 63.67+/-14.02 kg, mean height = 167.92+/-9.58 cm) completing the crossover hop-for-distance test, we recorded maximum DH for each leg and calculated the LSI of each subject. We performed 2 separate step-wise regression analysis models to develop predictive equations for DH and LSI. RESULTS: Age (r = 0.36), weight r = 0.41), and body fat percentage (r = 0.58) were significant predictors of DH, with the regression model explaining 59% of the variability. None of the measured variables were significant predictors of LSI (r = 0.03). The regression model explained only 3% of the variability of LSI. CONCLUSIONS: The LSI for the crossover hop-for-distance test can be compared among all individuals without subdividing into groups. Subject characteristics should be as homogeneous as possible when comparing DH among subjects or groups.

Adipose Tissue↗
PubMed2001

Solid-phase microextraction of hop volatiles. Potential use for determination and verification of hop varieties.

The composition of hop essential oil is an important tool for evaluation of hop quality. As each hop variety has a typical essential oil pattern (fingerprint), hop oil analyses can be used to distinguish between hop varieties. The headspace solid-phase microextraction (SPME) method as described in this contribution is a simple sample preparation technique and represents an alternative procedure for essential oil fingerprint determination. Different SPME parameters (extraction temperature, extraction time and sample mass) were studied and the results were compared with those obtained by the routine distillation method. It is shown that SPME results can be used for determination and verification of varieties grown in Slovenia by means of principal components analysis.

Chromatography, Liquid↗
PubMed2003

Hopping to the beat. Hop regulation of cardiac gene expression.

Hop is a recently discovered homeodomain only protein with atypical characteristics. Unlike other homeodomain proteins, Hop lacks DNA binding activity, although it localizes predominantly to the nucleus. During embryogenesis, Hop is expressed in the myocardium of the developing heart and it functions downstream of Nkx2-5, an early cardiac-specific transcription factor. One role of Hop is to modify the expression of cardiac-specific genes and thereby finely regulate heart development. This article reviews the discovery, characteristics, roles, and future perspectives of Hop.

Amino Acid Sequence↗
PubMed2006

Comparison of the odor-active compounds in unhopped beer and beers hopped with different hop varieties.

Odorants comprising the hop aromas of beers were examined. Strongly hopped beers with Saazer, Hersbrucker, and Cascade hops were compared with unhopped beer by gas chromatography-olfactometry (CharmAnalysis) and sensory evaluation. Twenty-seven odorants were revealed as hop-derived, which derived either directly from hops or via metabolization, and 19 components were identified. Of the components, linalool, geraniol, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, and ethyl 2-methylpropanoate were determined as odor-active components from their Charm values and aroma values. The muscat-like aroma of Cascade beer and the spicy aroma of Hersbrucker beer were predominant in sensory evaluation, and the contributors to these characteristics were investigated.

Beer↗
PubMed2005

Cloning and molecular analysis of the regulatory factor HlMyb1 in hop (Humulus lupulus L.) and the potential of hop to produce bioactive prenylated flavonoids.

The concentrations of prenylated chalcones and bitter acids were analyzed in Czech hop varieties. The highest levels of (xanthohumol + desmethylxanthohumol) (0.97%, m/m) and of total bitter acids (17.19%, m/m) were observed for cv. Agnus. The concentration ratios of bitter acids to prenylated chalcones varied depending on the genotype, thereby suggesting genetic determination by different set(s) of structural and regulatory genes. Promoter elements of the chs_H1 gene encoding a "true"chalcone synthase, a candidate gene to co-determine the biosynthesis of prenylated chalcones, were analyzed, and several boxes for cis-regulatory elements including Myb transcription factors were discovered. A cDNA library was established from glandular tissue-enriched cones of cv. Osvald's clone 72 and used to screen for Myb regulatory elements. The cDNA of the first Myb regulatory factor from hop, called HlMyb1, was cloned and analyzed. The HlMyb1 open reading frame encodes 272 amino acids (29.8 kDa), and the protein showed highest homology to the light-regulated factor AtMyb68 from Arabidopsis thaliana within the Myb domain, whereas there was no significant homology with known MYB proteins outside this domain. Unlike AtMyb68, which is expressed in mature leaves, HlMyb1 is strongly expressed in hop inflorescences and could participate in the regulation of developmental processes involved in the production of hop cones and bioactive secondary metabolites.

Acyltransferases↗
PubMed1988

The molecular structure of hop latent viroid (HLV), a new viroid occurring worldwide in hops.

A new viroid which does not seem to produce any symptoms of disease, and is therefore tentatively named hop latent viroid (HLV) was found to occur worldwide in hops. HLV proved to be infectious when mechanically inoculated onto viroid- and virus-free hops. The viroid nature of HLV was also substantiated by sequence analysis which revealed that HLV is a circular RNA consisting of 256 nucleotides, that can be arranged into the viroid-specific, rod-like secondary structure. HLV also contains the central conserved region typical for most of the presently known viroids. However HLV does not contain the viroid-specific oligo(A) stretch in the upper left part of its rod-like molecule. Because of this feature and a sequence similarity with the prototypes of the other viroid groups below 55%, HLV can be regarded as the first member of a new viroid group.

Base Sequence↗
PubMedDate not supplied

An improved NMR method for the quantification of alpha-acids in hops and hop products.

A new and independent method for the quantification of alpha-acids in hops and hop products has been developed. NMR was used as a qualitative method for the complete assignment of all 1H- and 13C-NMR signals of the three main alpha-acids, cohumulone (1), humulone (2) and adhumulone (3). In a 13C two-dimensional INADEQUATE experiment, the 13C-NMR spectrum of 1 was unambiguously assigned via the carbon-carbon connectivities. Use of NMR as a quantitative method allowed quantification of the pure and individual alpha-acids 1 and 2, and the determination of the absolute concentration of solutions of these compounds. Quantification of alpha-acids by NMR is less complicated and more reliable than the methods used until now.

Cyclohexanones↗
PubMed2001

Molecular characterization of Hop mosaic virus: its serological and molecular relationships to Hop latent virus.

The 3'-terminal sequence of hop mosaic virus (HpMV) genomic RNA was determined. A cDNA of approximately 1.8 kbp was amplified from the HpMV genome by 3' RACE using a degenerate primer, which was designed to anneal to the overlapping region of open reading frames (ORFs) 2 and 3 of eight carlavirus genomes. The sequence contained three ORFs, encoding proteins of 7-, 34-, and 11-kDa, which corresponded to ORFs 4, 5, and 6 of the carlavirus genome, respectively. The amino acid sequence of ORF 5, encoding the coat protein (CP) of HpMV, shows the highest identity (67%) to that of Hop latent virus (HpLV). The HpMV CP N-terminal sequence differs from that of HpLV, but the central and C-terminal sequences of the CP of both viruses are similar. The sequence similarity possibly causes the cross-reaction of heterologous antibodies of HpMV and HpLV. Phylogenetic analyses based on the CP amino acid and 3' non-coding region sequences indicate close relationships among HpMV, HpLV, and Potato virus M. We report here the first molecular characterization of HpMV genomic RNA.

3' Untranslated Regions↗
PubMed2005

Broad spectrum anti-infective potential of xanthohumol from hop (Humulus lupulus L.) in comparison with activities of other hop constituents and xanthohumol metabolites.

This review summarizes the capacity of xanthohumol (XN) in comparison with additional hop constituents and metabolites to act as an antiinfective agent against microorganisms including bacteria, viruses, fungi and malarial protozoa. XN was shown to inhibit the Gram-positive bacteria Staphylococcus aureus and Streptococcus mutans. Antiviral activity was demonstrated against bovine viral diarrhea virus, cytomegalovirus, herpes simplex virus type 1 and 2 and human immunodeficiency virus 1. Inhibition of two Trichophyton spp. was indicative of antifungal activity. Finally, XN potently inhibited the replication of Plasmodium falciparum, the causative agent of malaria. This effect was linked to the inhibition of glutathione-mediated degradation and detoxification of haemin, a by-product of the parasitic digestion of haemoglobin. Overall, these activities further contribute to the broad spectrum of biological effects observed with XN.

Animals↗
PubMed2000

From classical mobility to hopping conductivity: charge hopping in an ultracold gas.

Studies of charge mobilities in an ultracold gas are reported. Calculations for the Na + Na+ system have been carried out as a function of temperature T and densities, and the conductivity of the ultracold charged gas is obtained. The total charge mobility exhibits a sharp increase as T is lowered, indicating a transition from an almost insulating to a conducting system at few microK. It is shown that the nature of the charge mobility changes with temperature: at high T, the charges are transported by massive centers (i.e., the ions), and at low T, by electrons jumping from neighboring atoms onto the positive ions (the positive holes exhibit hopping conductivity). An experiment is proposed to detect this effect.

Journal Article↗