Differential effects of the translocator protein 18 kDa (TSPO) ligand etifoxine and the benzodiazepine alprazolam on startle response to predictable threat in a NPU-threat task after acute and short-term treatment

RATIONALE

Benzodiazepines have been extensively investigated in experimental settings especially after single administration, which mostly revealed effects on unpredictable threat (U-threat) rather than predictable threat (P-threat). Given the need for pharmacological alternatives with a preferable side-effect profile and to better represent clinical conditions, research should cover also other anxiolytics and longer application times.

OBJECTIVES

The present study compared the acute and short-term effects of the translocator protein 18 kDa (TSPO) ligand etifoxine and the benzodiazepine alprazolam on P-threat and U-threat while controlling for sedation.

METHODS

Sixty healthy male volunteers, aged between 18 and 55 years, were randomly assigned to receive a daily dose of either 150 mg etifoxine, 1.5 mg alprazolam, or placebo for 5 days. On days 1 and 5 of intake, they performed a NPU-threat task including neutral (N), predictable (P), and unpredictable (U) conditions, while startle responsivity and self-reports were studied. Sedative effects were assessed using a continuous performance test.

RESULTS

Neither alprazolam nor etifoxine affected startle responsivity to U-threat on any of the testing days. While etifoxine reduced the startle response to P-threat on day 1 of treatment for transformed data, a contrary effect of alprazolam was found for raw values. No effects on self-reports and no evidence of sedation could be observed for either drug.

CONCLUSIONS

None of the anxiolytic substances had an impact on startle potentiation to U-threat even after several days of intake. The effects of the anxiolytics on startle responsivity to P-threat as well as implications for future studies are discussed.

Association of Chemokine (C-C Motif) Receptor 5 and Ligand 5 with Recovery from Major Depressive Disorder and Related Neurocognitive Impairment

INTRODUCTION

Inflammatory processes play an important role in the pathophysiology of major depressive disorder (MDD), but their relevance for specific symptoms such as neurocognitive impairment is rarely investigated.

METHODS

In this observational study, we investigated the changes of leukocyte chemokine (C-C motif) receptor 5 (CCR5) and ligand 5 (CCL5) mRNA levels and inflammatory cytokines in 60 MDD patients before (PRE) and after 5 weeks (W5) of antidepressive treatment in relation to therapy response and alterations in cognitive functions by means of the Cambridge Neuropsychological Test Automated Battery (CANTAB). We hypothesized that elevated CCR5 and CCL5 levels in depressed patients would decrease upon treatment and could differ with regard to cognitive impairment associated with MDD.

RESULTS

Both CCR5 and CCL5 levels were significantly decreased in the responder group compared to nonresponders even before treatment. The cytokine IL-6 as a marker of inflammation in depression did not show a difference before treatment in future responders versus nonresponders, but decreased significantly upon antidepressive therapy. Regarding neurocognitive impairment in MDD patients, an increased misperception of the emotion "anger" after 5 weeks of treatment proved to be associated with a more pronounced change in CCR5, and the perception of the emotion "disgust" became faster along with a stronger decrease in CCL5 over the same time. Executive functions typically impaired in MDD patients were not markedly associated with alterations in CCR5/CCL5.

DISCUSSION

CCR5 and CCL5 are important in the targeting of immune cells by HIV. This is the first study providing valuable hints that both CCR5 and CCL5 might also serve as markers of therapy response prediction in MDD. Regarding neurocognitive impairment in depression, CCR5 and CCL5 did not reveal characteristic changes upon MDD treatment such as executive functions, which are probably delayed. However, changes of emotional perception appear to be an earlier responding feature.

The cytokine IL-17A as a marker of treatment resistance in major depressive disorder?

Major depression is a complex disease and-among others, inflammation appears to play an important role in its pathophysiology. In this study, we investigated a broad range of cytokines in depressed patients. Plasma levels of interleukin (IL)-12/ IL-23p40, IL-15, IL-16, IL-17A, IL-1α, IL-7, tumor necrosis factorβ and vascular endothelial growth factor were compared in 48 patients suffering from major depression before, after one and after six weeks of antidepressive treatment in relation to therapy response. Interestingly, the level of IL-17A turned out to rise significantly in the non-responder group compared to responder during antidepressive treatment. IL-17A is a pro-inflammatory cytokine that initiates the production of other cytokines, thereby inducing and mediating immune response. It is also involved in allergic and autoimmune-related diseases. The database investigating the role of IL-17A in major depressive disorder has grown within the last few years comparing levels of this cytokine in depressed patients versus healthy subjects. However, little is known about the expression of IL-17A during the course of antidepressive treatment. In summary, our study provides valuable evidence that this cytokine might serve as a marker of therapy resistance to antidepressants.

Non-Fatal Intoxication with a High Dose of Citalopram in a Suicidal 14-Year-Old Girl

The use of selective serotonin reuptake inhibitors (SSRIs) like citalopram in the clinical treatment of depressive symptoms in children and adolescents has become increasingly common, although application is mostly off-label. The increasing number of prescriptions is not only due to their good efficacy, but also due to their good tolerability and the comparatively low risk in cases of intoxication. However, there is discussion about the cardiac safety of overdose ingestion of citalopram. Here, we report in detail on an adolescent with depressive symptoms who used 800 mg of citalopram in order to attempt suicide. In contrast to other case reports in adults, our patient showed only mild neurological symptoms and no cardiac toxicity or symptoms of a serotonin syndrome, despite a high citalopram blood concentration measured about two hours following ingestion of citalopram (633 ng/ml; therapeutic reference range for adults 50-110 ng/ml).

Classical Risk Factors and Inflammatory Biomarkers: One of the Missing Biological Links between Cardiovascular Disease and Major Depressive Disorder

BACKGROUND

Cardiovascular disorders (CVD) and major depressive disorder (MDD) are the most frequent diseases worldwide responsible for premature death and disability. Behavioral and immunological variables influence the pathophysiology of both disorders. We therefore determined frequency and severity of MDD in CVD and studied whether MDD without CVD or other somatic diseases influences classical and inflammatory biomarkers of cardiovascular risk. In addition, we investigated the influence of proinflammatory cytokines on antidepressant treatment outcome.

METHODS

In a case-control design, 310 adults (MDD patients without CVD, CVD patients, and cardiologically and psychiatrically healthy matched controls) were investigated. MDD patients were recruited after admission in a psychiatric university hospital. Primary outcome criteria were clinical depression ratings (HAM-D scale), vital signs, classical cardiovascular risk factors and inflammatory biomarkers which were compared between MDD patients and healthy controls.

RESULTS

We detected an enhanced cardiovascular risk in MDD. Untreated prehypertension and signs directing to a metabolic syndrome were detected in MDD. Significantly higher inflammatory biomarkers such as the high sensitivity C-reaktive protein (hsCRP) and proinflammatory acute phase cytokines interleukine-1β (IL-1β) and interleukine-6 (IL-6) underlined the higher cardiovascular risk in physically healthy MDD patients. Surprisingly, high inflammation markers before treatment were associated with better clinical outcome and faster remission. The rate of MDD in CVD patients was high.

CONCLUSIONS

Patients suffering from MDD are at specific risk for CVD. Precise detection of cardiovascular risks in MDD beyond classical risk factors is warranted to allow effective prophylaxis and treatment of both conditions. Future studies of prophylactic interventions may help to provide a basis for prophylactic treatment of both MDD and CVD. In addition, the high risk for MDD in CVD patients was confirmed and underlines the requirement for clinical attention.

Social capital in a regional inter-hospital network among trauma centers (trauma network): results of a qualitative study in Germany

Background

As inter-hospital alliances have become increasingly popular in the healthcare sector, it is important to understand the challenges and benefits that the interaction between representatives of different hospitals entail. A prominent example of inter-hospital alliances are certified ‘trauma networks’, which consist of 5-30 trauma departments in a given region. Trauma networks are designed to improve trauma care by providing a coordinated response to injury, and have developed across the USA and multiple European countries since the 1960s. Their members need to interact regularly, e.g. develop joint protocols for patient transfer, or discuss patient safety. Social capital is a concept focusing on the development and benefits of relations and interactions within a network. The aim of our study was to explore how social capital is generated and used in a regional German trauma network.

Methods

In this qualitative study, we performed semi-standardized face-to-face interviews with 23 senior trauma surgeons (2013-14). They were the official representatives of 23 out of 26 member hospitals of the Trauma Network Eastern Bavaria. The interviews covered the structure and functioning of the network, climate and reciprocity within the network, the development of social identity, and different resources and benefits derived from the network (e.g. facilitation of interactions, advocacy, work satisfaction). Transcripts were coded using thematic content analysis.

Results

According to the interviews, the studied trauma network became a group of surgeons with substantial bonding social capital. The surgeons perceived that the network’s culture of interaction was flat, and they identified with the network due to a climate of mutual respect. They felt that the inclusive leadership helped establish a norm of reciprocity. Among the interviewed surgeons, the gain of technical information was seen as less important than the exchange of information on political aspects. The perceived resources derived from this social capital were smoother interactions, a higher medical credibility, and joint advocacy securing certain privileges.

Conclusion

Apart from addressing quality of care, a trauma network may, by way of strengthening social capital among its members, serve as a valuable resource for the participating surgeons. Some member hospitals could exploit the social capital for strategic benefits.

Validation of a multiplex reverse transcriptase PCR ELISA for the detection of 19 respiratory tract pathogens

INTRODUCTION

Since acute respiratory tract infections inflict a high burden of disease in children worldwide, a multiplex reverse transcription polymerase chain reaction combined with a microwell hybridization assay (m-RT-PCR-ELISA) to detect 19 different respiratory pathogens was developed and validated.

METHODS

A total of 430 respiratory specimens were retrospectively tested in parallel by both the advanced 19-valent m-RT-PCR-ELISA as well as by culture or individual RT-PCR assays used in clinical routine.

RESULTS

The mean (median) sensitivity of the m-RT-PCR-ELISA in the retrospective test was 93.3% (95.1%; range 83.3-100 %), and the mean (median) specificity was 99.8 and 100 % (range 98.6-100 %), respectively. The mean positive predictive value was 99.3 % (range 93.4-100 %) and the mean negative predictive value was 95.3 % (range 98.4-100 %). Feasibility and clinical value of the 19-valent method was prospectively shown on 16,231 incoming clinical specimens from patients between 0 and 16 years of age with acute respiratory tract infections admitted to pediatric hospitals or private practices from October 2003 to June 2010 in three regions in Germany (Kiel, Mainz, Freiburg; Freiburg to June 2007 only). At least one microorganism was detected in 10,765 of 16,231 (66.3 %) clinical specimens: 5,044 RV, 1,999 RSV, 1,286 AV, 944 EV, 737 seasonal IVA, 173 pandemic IVA H1N1-2009, 899 MPV, 518 CV, 383 PIV3, 268 PIV1, 259 Mpn, 205 IVB, 164 PIV2, 144 PIV4, 103 Bp, 29 Cpn and 29 Bpp, while reovirus and Lpn were not present in these specimens from a pediatric population. More than one organism could be detected in 13.4 % of the specimens.

CONCLUSIONS

The m-RT-PCR-ELISA evaluated here improves the spectrum for diagnosing respiratory infections and is a feasible instrument for individual diagnostic and epidemiological studies.

Progranulin gene variability and plasma levels in bipolar disorder and schizophrenia

Basing on the assumption that frontotemporal lobar degeneration (FTLD), schizophrenia and bipolar disorder (BPD) might share common aetiological mechanisms, we analyzed genetic variation in the FTLD risk gene progranulin (GRN) in a German population of patients with schizophrenia (n = 271) or BPD (n = 237) as compared with 574 age-, gender- and ethnicity-matched controls. Furthermore, we measured plasma progranulin levels in 26 German BPD patients as well as in 61 Italian BPD patients and 29 matched controls.

A significantly decreased allelic frequency of the minor versus the wild-type allele was observed for rs2879096 (23.2 versus 34.2%, P<0.001, OR:0.63, 95%CI:0.49–0.80), rs4792938 (30.7 versus 39.7%, P = 0.005, OR: 0.70, 95%CI: 0.55–0.89) and rs5848 (30.3 versus 36.8, P = 0.007, OR: 0.71, 95%CI: 0.56–0.91). Mean±SEM progranulin plasma levels were significantly decreased in BPD patients, either Germans or Italians, as compared with controls (89.69±3.97 and 116.14±5.80 ng/ml, respectively, versus 180.81±18.39 ng/ml P<0.001) and were not correlated with age.

In conclusion, GRN variability decreases the risk to develop BPD and schizophrenia, and progranulin plasma levels are significantly lower in BPD patients than in controls. Nevertheless, a larger replication analysis would be needed to confirm these preliminary results.

Comparison of the BD Directigen Flu A+B Kit and the Abbott TestPack RSV with a multiplex RT-PCR ELISA for rapid detection of influenza viruses and respiratory syncytial virus

The Directigen Flu A+B enzyme immunoassay and the Abbott TestPack RSV enzyme immunoassay were each compared with a multiplex RT-PCR ELISA by testing 635 nasopharyngeal aspirates collected from children aged < 16 years who had been hospitalised with acute respiratory tract infection during the epidemic season 2002-2003. In this study, the sensitivity of the Directigen Flu A+B assay was unacceptably low (29.3% and 10.0%, respectively) for the detection of influenza A and B viruses. The sensitivity of the Abbott TestPack RSV assay (77.4%) was acceptable and in agreement with the multiplex RT-PCR ELISA.

Expression of connexins 40 and 43 in human left atrium in atrial fibrillation of different aetiologies

OBJECTIVE

To test the hypothesis that atrial fibrillation (AF) is associated with changes in the expression of connexins 40 and 43 in the left atrium with more pronounced changes in mitral valve disease than in lone AF.

METHODS

Protein concentrations of connexin 40 and connexin 43 were analysed in left atrial tissue of patients undergoing cardiac surgery. One group of patients had lone AF (n = 41), one group had AF and mitral valve repair (n = 36), and one group in sinus rhythm served as controls (n = 15).

RESULTS

Western blot analysis of connexin 40 and connexin 43 expression showed an increase of both gap junctional proteins (connexin 43 > connexin 40) in patients with AF of all forms compared with patients in sinus rhythm (p = 0.01 and p = 0.011, respectively). Subgroup analysis showed increased concentrations of connexin 40 in lone AF and AF with mitral valve disease compared with sinus rhythm (p = 0.06 and p = 0.029, respectively), whereas the same analysis for connexin 43 reached significance only in the mitral valve disease group (p = 0.031). No differences in connexin 40 and connexin 43 expression were detectable between lone AF and AF with mitral valve disease. Within the groups connexin 40 and connexin 43 expression did not differ between patients with paroxysmal AF and patients with chronic AF.

CONCLUSION

The present study shows for the first time that AF can induce changes in the left atrium with increased connexin expression. Furthermore, no systematic differences between patients with paroxysmal and chronic AF were detected.

Fibrosis in left atrial tissue of patients with atrial fibrillation with and without underlying mitral valve disease

OBJECTIVE

To examine the hypothesis that major extracellular matrix (ECM) proteins are expressed differently in the left atrial tissue of patients in sinus rhythm (SR), lone atrial fibrillation (AF), and AF with underlying mitral valve disease (MVD).

DESIGN

Case-control study.

PATIENTS

118 patients with lone AF, MVD+AF, and SR.

MAIN OUTCOME MEASURES

Collagen I, collagen III, and fibronectin protein expression measured by quantitative western blotting techniques and immunohistochemical methods.

RESULTS

Protein concentrations increased in patients with AF (all forms) compared with those in SR (all forms): collagen I (1.15 (0.11) v 0.45 (0.28), respectively; p = 0.002), collagen III (0.74 (0.05) v 0.46 (0.11); p = 0.002, and fibronectin (0.88 (0.06) v 0.62 (0.13); p = 0.08). Especially, collagen I was similarly enhanced in both lone AF (1.49 (0.15) and MVD+AF (1.53 (0.16) compared with SR (0.56 (0.28); both p = 0.01). Collagen III was not significantly increased in lone AF but was significantly increased in AF combined with MVD (0.84 (0.07) both compared with SR (0.46 (0.11); p = 0.01). The concentration of fibronectin was not significantly increased in lone AF and MVD+AF (both compared with SR). Furthermore, there was a similar degree of enhanced collagen expression in paroxysmal AF and chronic AF.

CONCLUSIONS

AF is associated with fibrosis. Forms of AF differ from each other in collagen III expression. However, there was no systematic difference in ECM expression between paroxysmal AF and chronic AF. Enhanced concentrations of ECM proteins may have a role in structural remodelling and the pathogenesis of AF as a result of separation of the cells by fibrotic depositions.

Severe complications of varicella in previously healthy children in Germany: a 1-year survey

OBJECTIVE

Varicella is a common infectious disease, usually benign and self-limited, and complications are believed to be rare. The purpose of this study was to describe the epidemiology of severe varicella complications in immunologically healthy children in Germany.

METHODS

Information on any admission of children with a severe complication associated with chickenpox was solicited throughout 1997 from all 485 pediatric hospitals in Germany using an established surveillance system. The case definition included nonimmunocompromised individuals who were up to 16 years of age and hospitalized with neurologic complications, bacterial superinfections, or hematologic complications.

RESULTS

The response rate to the surveillance questionnaire during the observation period was high: 93.4%. Of the 153 reported cases, 119 met the case definition. There was a seasonal distribution of reported complications with a peak in March. The majority of complications occurred in preschool-age children with a maximum age of 4 years. No gender predominance was found with a distribution of 56 female and 63 male patients. Multiple entries for complications were allowed. The most frequent complications were neurologic, which were reported in 73 children (61.3%); cerebellitis was the leading diagnosis (n = 48), followed by encephalitis (n = 22), meningitis (n = 2), and central facial palsy (n = 1). A total of 46 (38.6%) infectious complications were identified. Superinfections of the skin were present in 31 (26.0%), pyogenic arthritis was present in 5 (4.2%), osteomyelitis was present in 4 (3.3%), necrotizing fasciitis was present in 3 (2.5%), orbital cellulitis was present in 2 (1.6%), and pneumonia was present in 1 (0.8%). Streptococcus pyogenes was the leading cause of bacterial infections (18 cases [15.1%]), with invasive disease in 6 patients (8.4%) and linked to 4 of 8 cases with defect healing. Infectious complications were reported in the majority in younger children up to 4 years of age, whereas neurologic complications occurred more frequently in an older age range. Five children experienced thrombocytopenia or severe anemia. There was no bleeding disorder, no fatality, and no case of Reye syndrome reported during the 1-year observation period. In total, 8 (6.7%) of 119 patients reported having long-term sequelae, 6 attributable to infectious complications and 2 to persistent deficits after neurologic complications.

CONCLUSION

This is the first prospective nationwide study of severe complications of varicella in immunologically healthy children. Related to 14 025 867 children up to the age of 16, a crude incidence of severe chickenpox complications of 0.85/100 000 could be calculated [corrected]. The actual hospitalization rate attributable to complicated chickenpox is probably much higher, because this calculation refers to a population theoretically at risk and not the truly susceptible individuals. The results of this study demonstrate considerable morbidity with a comparatively high rate of encephalitis, osteomyelitis, and pyogenic arthritis. Although infectious complications were present in only 38.6% of the reported cases, they contributed disproportionately to the cases with chronic sequelae. Looking at these cases in more detail, S pyogenes involvement was identified as the major risk factor for invasive disease with an unfavorable long-term outcome. varicella-zoster virus, chickenpox/epidemiology, chickenpox/complications, encephalitis, cellulitis, osteomyelitis, necrotizing fasciitis, group A beta-hemolytic streptococci, Europe.

Hydantoin syndrome with holoprosencephaly: a possible rare teratogenic effect

We report on a newborn girl with lobar holoprosencephaly and clinical signs of hydantoin syndrome. During pregnancy the mother was treated with diphenylhydantoin and primidon for psychomotor and petit mal seizures. The possible relationship between hydantoin syndrome, holoprosencephaly, and maternal intake of anticonvulsants during pregnancy is discussed.

[Ultrasound hemolysis]

An ultrasound unit for hemolysis for an analytic device is presented which permits hemolysis without the need of a specific insonification chamber which is an unwanted discontinuity along the probe path. This is possible by direct insonification of a flexible tube which contains the flowing blood. The influence of ultrasound power, insonification time and coupling conditions on the result of hemolysis is investigated.

[Fluxes, accumulation and transport of Cl(-) in excised corn roots]

Fluxes, accumulation and transport rates of Cl(-) in excised corn roots were investigated.Flux equilibrium in 5×10(-4)M KCl was not reached within an experimental period of 28 hr.Transport of Cl(-) (5×10(-4)M KCl) through the xylem of 4-6 cm long excised corn roots had a lag of 1-2 hr. From 6 to 28 hr rates of accumulation and transport were nearly constant (5×10(-4)M KCl). The velocity of volume-flow within the xylem was 1.5-2 cm hr(-1) (5×10(-4)M KCl). (36)Cl(-)-efflux through the cut end of roots preloaded in K(36)Cl of low concentration exhibits a discontinuity which is explained by addition of two fluxes: efflux of ions concentrated in the xylem (and symplasm) plus efflux from the vacuoles through the xylem.Accumulation of Cl(-) by excised roots approaches a maximum level (Jackson and Edwards, 1966). Influx rates remain constant while efflux rates increase with time. It is shown in this paper that the flux of Cl(-) through the xylem becomes a large proportion of the influx across the plasmalemma. Flux rates suggest that more than 50% of the Cl(-) ions transported to the xylem passed through a vacuole (5×10(-4)M KCl; 20-28 hr).

[Anion influx, ATP level and CO2 fixation in Limnophila gratioloides and Chara foetida]

Influx of anions (5x10(-4) M Cl(-) or SO4 (2-)) across the plasmalemma, ATP levels and CO2 fixation in Limnophila and Chara have been measured in a comparative study.In Limnophila, influx, ATP level and CO2 fixation were progressively reduced by increasing concentrations of carbonyl cyanide m-chlorophenylhydrazone (CCCP) in the light (4000 lux) as well as in the dark. In Chara, not only influx but also ATP levels were much less reduced in the light than in the dark.At 5x10(-4) M external salt concentration the action of light or dark is to change active influx of anions. Thus this study provides strong evidence to support the view that active anion uptake is directly dependent on ATP rather than on electron flow or NADPH. The possible significance of differences in the photophosphorylation systems of various plants is stressed.

[Membrane structure in plants. Permeation of ions as a movement across an electrostatic barrier]

Efflux of ions across the plasmalemma of root cells was studied in order to understand how the plasmalemma acts as a barrier to passive ion distribution.

High external concentrations of salts (KCl, CaSO4 etc.) were found to increase the permeability of the plasmalemma to Cl⊖. The decrease in resistance of the plasmalemma to anion permeation was suggested to be due to binding of cations to negatively charged groups of the membrane. We have stressed the significance of binding of cations (Ca2⨁, H⨁, K⨁, Na⨁) to phospholipid films10 for the mechanism of ion permeation across the plasmalemma of plant cells1-4. H○-efflux from salt-loaded roots is likely to be stimulated with increasing external salt concentration. Efflux of Cl⊖ was stimulated by externally applied H2SO4. The different effect of Ca2⨁-salts on Cl⊖- and Rb® (K®)-permeability of salt-loaded roots suggests that it is not only he H⨁-ions which decrease the charge density of the membrane but also the Ca2O-ions (and monovalent cations at sufficient concentrations?). Thus Ca2⨁ increases passive anion permeability by decreasing the density of negative charges of the membrane and decreases passive (nonspecific) monovalent cation permeability. Ca2⨁ and H⨁ (K⨁, Na⨁) appear to act synergistically on Cl⊖-permeability and antagonistically on monovalent cation permeability.

The high Rb® (K®)-efflux across the plasmalemma (fig. 1) may contribute to the electric conductance and potential of the plasmalemma. The plasmalemma is to be expected to depolarize as the pH of the medium is lowered. However, this would not unequivocally point to H⨁-conductance as a major component f plasmalemma conductance (KITASATO 16), since permeability of the plasmalemma to Cl⊖(PCl) appears o be increased as the pH is lowered.

It is concluded that the plasmalemma of plant cells acts as an electrostatic barrier against anion diffusion. The lipid of the membrane favours the permeability to apoiar molecules as suggested by OVERTON 5 and COLLANDER 6. The general barrier action to the movement of polaf and charged molecules is believed to arise from a compact arrangement of cholesterol and apoiar hydrocarbon chains of phospholipids (and apoiar amino acid residues). Small polar molecules penetrate the lipid lattice easier than big polar molecules. However, the charged groups of the phospholipids play an important role in permeability to ions rather than the plasmalemma being an electrically neutral lipid filter.

[Effect of CCCP and UO 2 (++) on ion fluxes in roots]

Using the device shown in Fig. 1 of a previous paper (Weigl, 1969) efflux of Rb(+) from preloaded corn roots across the plasmalemma of root cortex cells was stimulated by addition of 5×10(-4) M UO 2 (++) , whereas the flux of Rb(+) into the xylem was inhibited by addition of 5×10(-4) M UO 2 (++) . Efflux of Cl(-) across the plasmalemma was stimulated by 10(-5) M CCCP, the flux of Cl(-) via the xylem was inhibited by 10(-5) M CCCP. The problem of interpreting efflux experiments with roots is stated and discussed.

[Mechanism of cis- and trans-stimulation of anion fluxes across the plasma membrane of plant cells]

Trans-stimulation by salts of the passive efflux of Cl⊖ across the plasma membrane of plant cells was established previously. In this paper the trans-effect of salts is compared with the effect of nystatin on ion efflux. It is further shown that the influx of anions is also stimulated by external salts. Influx of Cl⊖ was stimulated by K2SO4 (>~1 mM), influx of SO4 2⊖ was stimulated by KCl (>~lmM). This suggests that with increasing external salt concentration not only the electrical potential across the plasmalemma is lowered (due to preferential permeability to monovalent cations) but alsoth e permeability (i. e. the permeability coefficient) of the plasmalemma to anions is increased. According to the model proposed for the salt-stimulated decrease in the resistance to passive anion permeation the plasmalemma may be considered a lipid lattice-electrofilter. The nature of the coupling of the counter fluxes is discussed.

[Efflux and transport of Cl(-) and Rb (+) in corn roots. Action of external KCl, Ca(++), EDTA and IAA]

The efflux of (36)Cl and (86)Rb and the fluxes of these ions into the xylem were investigated using the device shown in Fig. 1.Efflux of (36)Cl is stimulated by external KCl while transport into the xylem is inhibited. Stimulation of the efflux appears to be stronger than inhibition of the transport.The stimulation of the efflux of (36)Cl was also observed with roots of intact seedlings.Assuming that the mode of transfer of Cl(-) into the xylem (flux 3, Fig. 8) is diffusion exhibiting a linear isotherm (LUTTGE and LATIES, 1966), these results suggest that the primary action of external salts is on the efflux across the plasma-lemma (WEIGL, 1967, 1968). We were unable, however, to find a linear relationship between concentration and rate of chloride transport to the shoots of intact seedlings.With respect to the mode of ion transfer to the xylem (WEIGL and LüTTGE, 1965; LUTTGE and LATIES, 1966) we have to be aware of the following facts:A linear isotherm cannot be taken to signify diffusive permeation (TORII and LATIES, 1966; LUTTGE and LATIES, 1966). If the Michaelis constant is extremely high relative to the ion concentration, the relationship between the ion concentration and the rate of a metabolic or mediated transport approaches linearity.The isotherm of the transport into the xylem may primarily reflect the difference of two large fluxes (4 and 5; Fig. 8).The transport data of LUTTGE and LATIES (1966) need not be presented as a straight line (Fig. 6).If at high external ion concentrations the ratio of the ion concentration in the exudation sap to the external ion concentration approaches unity, diffusive permeation into the stele is still not proved to be the mode of migration, since at high stelar ion concentration flux 6 tends to become equal to flux 3.Considerations on radial ion transfer into the xylem depend on contemporary knowledge of the location of transport systems. Cl(-)-uptake into root tips (2 mm) from solutions of 1-10 mM KCl did not exhibit a linear isotherm. These results are unpublished since the discrepancy to the results of TORII and LATIES (1966) may be due to a higher content of vacuoles in our root tips. We feel it unlikely, however, that a linear isotherm of Cl(-)-uptake into root tips is adequately explained by assuming that it is due to a lack of vacuoles while the sensibility to inhibitors is assumed to be due to the presence of vacuoles in root tips.Transport of Cl(-) into the xylem is susceptible to inhibitors of oxydative phosphorylation, suggesting that this process, even at high external ion concentrations, is dependent on metabolic energy in contrast to the passive efflux from the cortical cells across the plasmalemma into the environment of the root. The precise location of the metabolic step(s) on the pathway of ions from the environment of the root to the xylem is unknown.The observed effects of Ca(++), EDTA and IAA may be considered in relation to the theory that auxin exerts its influence on growth by altering the diffusion potential across cell membranes (BRAUNER and DIEMER, 1967). Growth is susceptible to the effect of Ca(++) and EDTA (ADAMSON, 1962; SETTERFIELD, 1963; THIMANN, 1963). Nevertheless, since IAA exerts no influence on ion fluxes in corn roots, it is not clear whether IAA really exerts its influence on growth by altering the diffusion potential across plant cell membranes. We might be dealing with occasional effects of secondary importance.

[Exchange mechanism of ion transport in corn roots]

The effect of the external anion concentration on the rate of efflux of anions from corn roots was investigated by following the efflux of labeled anions in shaken solutions of different concentrations of unlabeled anions.Rates of efflux of phosphate and chloride from corn roots are rather independent of external concentrations of the anions as long as these concentrations are low.Rates of efflux of phosphate and chloride from corn roots at high external concentrations of these ions were found to be a function of the external concentrations.Stimulation of efflux is specific: phosphate efflux is stimulated only by phosphate and not by chloride in the medium and vice versa. Since it appears unlikely that this effect is due to specific changes in the permeability of the membranes, it may by concluded that the specific stimulation of efflux by external ions as observed in this investigation is caused by ion exchange at mobile membrane units (WEIGL, 1967a). Reasons for this hypothesis are discussed and alternative hypotheses such as that calling for the protoplasm to function as ion exchanger with various specific binding sites are examined. The latter hypothesis remembers to the theory that "the ion carrier is the protoplasm itself" (OVERSTREET, 1957; BANGE and MEIJER, 1966), which diminishes the importance of membranes as limiting boundaries.

[Evidence for mobile transport structures (carriers) involved in ion transport in plants and kinetics of anion transport in elodea in light and dark]

Influx and efflux of anions in leaves of Elodea canadensis were investigated. A major component of phosphate efflux was found to be a function of the external phosphate concentration in accord with saturation kinetics, i.e. it was found to be proportional to phosphate influx. This suggests that the transport structures which mediate ion transport in plant membranes are mobile and can work in both directions (Fig. 7C). The higher the external concentration the more bound ions (A b (-) , Fig. 7C) are exchanged for external ions (A a (-) ) instead of being transported back to the inside of the membrane. Thus it was demonstrated that ion transport in plants is mediated by carriers or transportases. The action of the carriers is supported by ATP or another "energy-rich" compound which is regenerated by ATP; ATP may be supplied by the mitochondria or/and chloroplasts. In line with these findings some transport phenomena exhibited features of coenzyme kinetics.Magnitude and molecular nature of the carrier motion are unknown. There is no evidence for rotating or shuttling monovalent carriers. The carriers may be polyvalent and may be part of bigger structural units within the membrane. Nevertheless, these experimental observations are rather consistent with the idea that plant membranes contain tertiary or quarternary formed proteins or lipoproteins than with the conventional lipid bilayer models of cell membranes.

[Purification of the proteinase from Nepenthes pitcher secretion]

The proteolytic enzymes from the sterile secretion of the pitchers of 3 Nepenthes species were purified to electrophoretic homogenity by chromatography on Ecteola cellulose. The properties of the purified enzymes were investigated.

The enzymic hydrolysis of carrageenan by Pseudomonas carrageenovora: purification of a kappa-carrageenase

Enzymes specific for the κ and λ fractions of carrageenan were obtained from the cell-free culture medium of Pseudomonas carrageenovora. These enzymes were concentrated by precipitation with ammonium sulfate and separated by chromatography on hydroxylapatite.The κ-carrageenase was purified to electrophoretic homogeneity by incubation at 35 °C and chromatography on DEAE cellulose. The enzymic hydrolysis of κ-carrageenan was accompanied by a rapid fall in specific viscosity and increase in reducing power. The products were a homologous series of sulfated oligosaccharides with 3-O-(3,6-anhydro-α-D-galactopyranosyl)-D-galactopyranose-4-O-sulfate (neocarrabiose-4-O-sulfate) as the major degradation product, and an enzyme-resistant fraction. The alkali-modified enzyme-resistant fraction was degraded by the κ-carrageenase.