Toxikologische Bewertung von Ochratoxin A: Offene Fragen und Forschungsbedarf

Ochratoxin A (OTA) is an important food and feed contaminant with potential adverse effects in humans and animals. In view of present discussions on limit values for OTA in foods, essential elements of a toxicological risk assessment are outlined. The exposure situation in Europe is now well documented. The data base, with respect to a characterization of hazard and dose-response relationships, allowed to calculate a provisional tolerable daily intake for OTA suited to protect the consumer against undesirable toxic effects. Nonetheless, further research on OTA is indicated in view of unresolved issues regarding the following points:

1. 1.
   mechanisms of action (mode of genotoxicity, role of bioactivation/metabolism, identification of DNA-adducts and dose-dependency);
    
2. 2.
   combinations of OTA and other mycotoxins (studies of relevant mixtures/conditions);
    
3. 3.
   individual susceptibility and/or situation-based vulnerability.
    

Better information on mechanistic aspects of mycotoxin-induced toxicities will further improve our knowledge on the “margin of safety” between a given exposure and a potential impairment of human health.     

Hormonal requirement for ovum implantation

Hormonal requirement for ovum implantation varies among the species of animals. The methods attempting to clarify the requirement in each species may be classified as follows:

1. (i)
   hormonal replacement therapy after removal of the pituitary or/and the ovaries
    
2. (ii)
   hormonal treatment after reduction of specific hormones by its antiserumin vivo
    
3. (iii)
   close observation of hormone secretion pattern in early pregnancy
    
4. (iv)
   examination of physiological conditions where implantation is delayed and analyze the hormone levels and the receptivity of the target tissues
    
5. (v)
   examination of effects on hormone levels and the receptivity of target tissues of drugs which interfere with implantation. The reported results indicate that both progesterone and estrogen are needed for implantation in rats, mice, and Mongolian gerbils; in other species of animals progesterone alone may be sufficient to induce implantation, although synergistic effect of estrogen appears to be seen in some species such as in the rabbit. It remains to be determined whether the blastocysts of those animals that need only progesterone for implantation have greater ability to produce estrogen than the blastocysts of the animals that need both progesterone and estrogen. Control mechanism of secretion of progesterone and estrogen for inducing implantation may be different in various species. It has been suggested that both leutropin and follicle stimulating hormone are needed for pre-implantation estrogen secretion in the rat, whereas only follicle stimulating hormone is needed in the mouse. In the species where the obligatory delay in implantation is observed, neuroendocrine mechanisms are reported to be involved in controlling the pituitary-ovarian function that causes a delay in implantation.
    

     

Rehydration improves the ductility of dry bone allografts

Processing of bone allografts improves infectious safety and allows storing bone substitutes at room temperature. The aim of this study was to compare mechanical properties of the processed Osteopure? bone with fresh frozen bone. All the samples were pieces from femoral heads retrieved during hip arthroplasty operations. The processing includes chemical decellularization, drying and irradiation with 25 kGy. Three types of samples were tested:

1. 1.
   fresh frozen thawed wet,
    
2. 2.
   dry non-rehydrated graft
    
3. 3.
   dry rehydrated graft.
    

In the 3-point bending test Young’s modulus and stress at break yielded no significant difference among the 3 different sample groups. Rehydrating of the dry graft showed increased ductility in strain at break test compared with the other 2 groups (p = 0.003). In compression tests dry grafts had significantly higher maximum effective stress and apparent maximum deformation compared with the grafts of other groups (p < 0.05). Processed bone has almost similar mechanical properties compared with fresh frozen bone. However, rehydration of processed dry graft increases its ductility. These grafts may tolerate bending forces better before breakage.

     

Preparation of allogeneic bone for alveolar ridge augmentation

Implant treatment is safe and predictable with sufficient amount and quality of bone tissue. In case of severely reduced bone tissue after a tooth was lost, augmentation of such tissue is necessary before implant embedment. Retrospective evaluation covered 380 alveolar ridge reconstructions. The study material consisted of human grafts prepared by the Department of Transplantology and Central Tissue Bank, Medical University of Warsaw. Presentation of laboratory procedures in the context of physical parameters of frozen, radiation sterilised, allogeneic corticocancellous material was presented. The preparation process makes it possible to obtain two types of bone material: granules and blocks. Women underwent 164 procedures with the use of bone granules and 61 augmentations with bone blocks. In case of men 122 packages of granules were used as well as 33 bone blocks. Based on the results an evaluation of usability of available allogeneic grafts was performed with reference to planned alveolar ridge augmentation procedures, which they were used for.

1. 1.
   The opportunity to prepare allogeneic material of different textures allowed selection to meet augmentation requirements while providing biological safety.
    
2. 2.
   Allogeneic granules should be used in multi-wall defects, such as a double, closed sinus lift and post-extraction socket augmentation.
    
3. 3.
   Owing to their superior mechanical parameters, bone blocks were successfully used in extending the width and height of the alveolar ridge and in open sinus lifts with one-wall or two-wall defects and adequate location of the lamellar bone in a graft prevented substantial graft resorption.
    

     

Über die “forme elliptique” der primitiven Ammonoidea

In Devonian ammonoids occur two different developments of the initial whorl, called by J.Barrande the “forme elliptique” and the “forme circulaire”. The first one is characterized by a less pronounced curvature of the first half whorl, the second one by a circulare curvature that begins already in the earliest stage. The forme elliptique is here interpreted as an archaic phenomenon, its incomplete curvature being a hereditary feature homologous to the orthoconic to cyrtoconic shape of the ancestral bactritids (a. o.Cyrtobactrites) and preserved in the earliest ontogenetic stages of ammonoids. This Suggestion is supported by the following facts:

1. a)
   The occurrence of the forme elliptique is restricted to the stratigraphically oldest (Lower to early Middle Devonian) and morphologically most primitive ammonoids (all Mimoceratidae; in the Agoniatitidae and Anarcestidae: only genera having an umbilical Perforation).
    
2. b)
   All genera advanced as far as having lost their umbilical Perforation, have developed exclusively the forme circulaire.
    
3. c)
   In the sequence of genera considered by H. K.Erben as the origin of the Ammonoidea, there is a particular distribution in the frequency of both developments:
    

Anetoceras = elliptique predominant, circulaire unknown —Teicherticeras = ? —Convoluticeras = elliptique predominant, circulaire occurring but rarely —Mimagoniatites = elliptique less frequent, circulaire common —Anarcestes = elliptique occurring rarely, circulaire strongly predominant — succeeding genera = no elliptique, circulaire occurring exclusively.Thus, the forme elliptique appears as a primary feature that became replaced successively during the evolution of the earliest ammonoids by the forme circulaire.The appearance of subtrigonal initial whorls and of a “second umbilical perforation” is discussed.     

Assessment of right atrium dysfunction in patients with obstructive sleep apnea syndrome using velocity vector imaging

Background and Objectives

This study aimed to assess the changes of RA function in patients with obstructive sleep apnea syndrome (OSAS) using velocity vector imaging (VVI) and to evaluate the application of VVI technology.

Methods

According to the apnea–hypopnea index (AHI), 71 patients with OSAS were divided into three groups: mild, moderate, and severe. A total of 30 cases of healthy subjects were enrolled as the control group. Digital images of apex four-chamber views were acquired to measure the right atrium (RA) linear dimensions and volume parameters including RA longitudinal diameter (RAL), transverse diameter (RAT), RA maximum volume (Vmax), RA minimum volume (Vmin), right atrial volume before contraction (Vpre). Right atrial volume parameters were corrected by body surface area (VImax, VImin, VIpre). The total right atrial emptying fraction (RATEF), right atrial passive emptying fraction (RAPEF), right atrial active contraction emptying fraction (RAAEF) were calculated. The VVI data measuring right atrial global strain (RA-GLS), right atrial strain rate in ventricular systolic phase (RA-SRs), right atrial strain rate in ventricular early diastolic phase (RA-SRe), right atrial strain rate in ventricular late diastolic phase (RA-SRa).

Results

1. 1.
   RA linear dimensions and volume parameters in severe OSAS were higher than those of control group. RAPEF in severe group was lower than control group and mild OSAS group (t?= 2.681, P?=?0.021; t?= 2.985, P?=?0.011; respectively). RAAEF in OSAS moderate group was higher than that of control group (t?= 3.006, P?=?0.02), and without statistical difference (P?>?0.05) in the severe OSAS group and the control group.
    
2. 2.
   RA-GLS in moderate OSAS group was significantly lower than that of control group (t?= 2.333, P?=?0.040) and reduced more obvious in the severe OSAS group (vs control, t?= 3.25, P?=?0.008, vs mild; t?= 3.011, P?=?0.012; respectively). RA-SRe in moderate and severe OSAS groups were lower than control group (t?= 2.466, P?=?0.031; t?= 3.547, P?=?0.005; respectively). RA-SRs of OSAS in severe group was lower than that of control and mild groups (t?= 3.665, P?=?0.004; t?= 3.204, P?=?0.008; respectively). RA-SRa in severe OSAS group was lower than that of control group (t?= 2.425, P?=?0.034).
    
3. 3.
   Multivariate regression analysis showed that RA-GLS and RA-SRe were independently correlated with AHI (t?=???2.738, P?=?0.010; t?=???2.191, P?=?0.036; respectively).
    

Conclusion

RA function was impaired in patients with OSAS. On hemodynamics, the change of RA function performed increased of reserve function, reduced pipeline function and increased of contraction function. However, the strain and strain rate reduced in different degree. RA-GLS and RA-SRe decreased the earliest, which suggested that strain and strain rate were the parameters which can reflect myocardial function damage earliest. VVI can more earlier and accurately detect myocardial dysfunction of right atrium in patients with OSAS, which is expected to be a worthy technique for early clinical therapy in patients with OSAS.

     

The effect of deoxycholate on yeast cell permeability

1. (1)
   Мембраны ненарушенных клеток дрожжей непроницаемы для солей янтарной кислоты и феррицианида, так что в их суспензии не наблюдается сукцинодегидрогеназы с феррикианидом как акцептором электронов.     
   
   

Effect of small doses of X-rays on formation of colour variants bySerratia marcescens

1. (1)
   Клетки Serratia marcescens, которые выжили после повторных облучений лучами Х, при новй однокртном облучении процент цветных мутантов. Процент мутаций возрастает в зависимости от дозы облучения ночти линейно.     
   
   

Stimulation of antibody formation by bacterial lipopolysaccharide. The influence of repeated doses of lipopolysaccharide on antibody formation

1. (1)
   Липополисахарид стимулирует образование антител даже при 8-кратном введении в сочетании с частично очищенным дифтерийным анатоксином.     
   
   

Adaptation of yeasts and bacteria to antimicrobial substances during continuous-flow cultivation

1. (1)
   Различные методы ад аптации из дрожжей и бактерий к антимикробным веществ, рассматриваются, а также Преимущество использования условий непрерывного потока для определенных целей.     
   
   

Contribution to the classification of actinomyces antibioticus

1. (1)
   Изучались морфологические, культуральные и физиологические свойства двух штаммов Actinomyces antibioticus, продуцентов актиномицина и олеандомицина.     
   
   

Dynamics of changes in specific hypersensitivity and of the nonspecific increase in sensitivity to endotoxin in BCG-sensitized mice

1. (1)
   На различных сроках после сенсибилизапии белых мышей различными дозами вакпины BCG исследовались количествнные измения спепифической гиперсенситивности, а также изменения неспецифической чувствительности.     
   
   

Conditions of the formation of pyrogenic substances by delayed hypersensitive cells in contact with antigenin vitro

1. (1)
   В ряде систематических оплтов дыли подробно определены биологические условия возникновения пирогенных веществ при реакции гиперсензитивных клеток со специфическим антигеном in vitro, влияние количества клеток и антигена, температуры и продояжительности инкудации, жизнеспосодности клеток и т. п.     
   
   

Metabolism of the mutantSaccharomyces cerevisiae R 12 A

Влияние кислорода на метаболизм респирационно-дефицитного мутанта Saccharomyces cerevisiae R 12 A в присутствии глюкозы изучалось на основании следующих критериев:

1. (1)
   потребление глюкозы среды и распределение ее атомов углерода по различным участкам клетки     
   
   

Physiological character of protein turnover in non-growing bacterial cells

1. (1)
   В серин-отрицательных и глицинотрицательны хклетках Escherichi coli После их переноса в среду, лишенную азота, оборот (turnover) белков протекает со скоростью около 1% в час. Его скорость зависит от количества клеток в 1 мл среды.     
   
   

A Contribution to the problem of phosphorylation in yeast

1. 1.
   Было подтверждено, ч т о в дрожжах образцов, используемых Stickland (1956) Помимо глюкозы не вы зывает уменьшение в общей сложности ки слотно-извлекаемые ф осфат уровня, которы й находится в несогл асии с другими автор ы которые найдены со кращение примерно Параллельно с этим н еорганических фосф атов.     
   
   

Determination of residual water in freeze-dried bacterial cultures by Fischer’s method

1. (1)
   Метод K. Fischer оказался быстрым, точным и вполне воспроизводимым методом исследования уменьшения количества воды в лиофилизированной суспензии дактерий. в сравнении с гравиметрическим методом, по методу фи более выcoKne данные.     
   
   

Demonstration of species non-specificity of the effect of hypersensitivity pyrogen

1. (1)
   Изучалась видовая специфичность действия пирогенных веществ, возникающих при взаимодействии экст рактов клеток с поздней гиперсенситивностью со специфическим антигеном in vitro (т. н. гиперсенситивный пироген).     
   
   

Formation of osmotically fragile rods by the action of lysozyme onBacillus megaterium KM

1. (1)
   В течение непродолзительной инкубации Bacillus megaterium в среде с 0,5 M фосфатным буфером и лизоцимом (0,2 мг/мл) вознпкают осмотически хрупкие клетки.     
   
   

A chromatographic determination of gibberellic acid

1. (1)
   Гибберелловую кислоту можно определить хроматографически в ферментационной Зидкости, в препаратах гиббереллина и в различных стадиях экстракции при помощи буферной бумаги и n-амилацетата. Синие пятна, получаемые после применения реагента Folin-Ciocîlteu смывают и окраску определяют фотометрически.