Zinc unbound concentration as an anchor to drive individualize repletion

BACKGROUND AND AIMS

Zinc (Zn) quantification is of particular interest in many clinical condition (e.g. inflammatory disease, critical care). Currently, Zn status is assessed by measuring plasma/serum concentration. This concentration corresponds to the sum of unbound Zn (Zn-Cu) and Zn highly bound to albumin (Zn-Cb).

METHODS

Using a pharmacokinetic approach to the interpretation of total Zn concentration (Zn-Ct), taking into account Zn-Cu and the influence of hypoalbuminemia on Zn-Cb, it is possible to improve the individualization of Zn repletion.

RESULTS

Therefore, during pregnancy and in certain inflammatory disease situations, repletion may not be necessary. However, as in critical care, it would be more appropriate to perform Zn-Cu assays to improve Zn repletion.

CONCLUSION

Coupled total and unbound Zn should be monitored in order to individualize Zn repletion.

Access to emergency care units by socially vulnerable patients: a qualitative research

Background

The increasing prevalence of chronic diseases, the decline in medical demography, the ramp up of new information and diagnosis technologies, together with the growing health social inequalities urge decision makers to rethink the access to emergency care units (ECU) and reduce the rate of multiple admissions, especially for people living in vulnerable conditions. Beyond the medical causes of access to ECU, it is crucial to understand the psychosocial representations of patients and health professionals.

Methods

23 socially vulnerable patients who have already been admitted within the last 3 months and ECU health/social professionals were interviewed face-to-face by a psychosocial scientist using a semi-directed approach, in 3 hospitals. The thematic content of data was analyzed in order to identify salient social representations of access to ECU.

Results

27 themes emerged to understand the issue of the access to ECU, joining into 5 main categories: perceived needs for access to ECU, perception of precariousness, the relationship of patients and professionals with the healthcare system, the shared experience of aggressiveness in ECU, expectations in post-emergency support. As regards the needs for access to ICU, several issues were identified: exemption from making upfront payments, needs for listening, support, reinsurance, privacy and consideration of emergency professionals, referral by general practitioners (GP), difficult access to GP, needs for immediacy and timely healthcare services, permanent opening of ECU. As regards the experience of ECU professionals: ambivalent emotions towards socially vulnerable patients, a recurrence of passages leading to a reduced medical attention, a feeling of failure to care for vulnerable patients, coping strategies in caring for these patients.

Conclusions

Our results bring several leads to improve the organization and the management of healthcare in ECU and in primary care for socially vulnerable patients.

Key messages

To identify the psychosocial rationales of access to emergency care units provides several leads to build a more efficient healthcare policy and reduce the burden of overloaded services. To reduce the overburden of emergency services can only be achieved by a global approach of the access to both emergency and primary care and a better support after emergency discharge.

Identifying binge-eating disorders in obese young people living in vulnerable areas of Marseille

Background

While anxiety, depression and self-esteem have been identified as contributors to obesity, binge-eating disorder (BED) also requires attention to avoid worsening obesity. However, handling obese young people living in vulnerable neighbourhoods is rather difficult both in terms of psychosocial representations of obesity and the poor care offer. The objective of our exploratory research is to study the impact of a dedicated multidisciplinary management program on anxiety and depression of obese young adolescents presenting with, or not, a binge-eating disorder.

Methods

Twelve patients (7 girls, 5 boys; mean age: 12.8 +/-1.3 years, range: 11-17) participated so far in this ongoing study. The mean body mass index was 36.5 +/- 7.2 (range: 27-53.4) for the group. They were all residents of vulnerable neighbourhoods of Marseille (France). They were evaluated at inclusion and 3 months after the 6-weeks program with the following self-questionnaires: Adolescent Binge Eating Disorder scale (ADO-BEDS), Hospital Anxiety Depression (HAD), 6-item Kutcher Adolescent Depression Scale (KADS-6), Self-esteem Measurement Scale for Adolescent (EMESA).

Results

So far, only 3 patients were evaluated pre- and post-management. For two patients with ADO-BEDS scores at inclusion and post-management showing the presence of a BED, the KADS-6 and EMESA (general and physical appearance items) scores improved at 3 months. The remaining patient, without any depression signs at both inclusion and after 3 months, experienced a decreased self-esteem while a BED, not assessed at inclusion, was clearly revealed at 3 months. BMI did not change from pre- to post-management.

Conclusions

Our clinical impression is that participating to the management program failed, at least for our first patients, to make them engage in a psychiatric/psychological therapy. Nevertheless, the program contributed to provide a motivating support system allowing them and their parents to become involved in their care.

Key messages

A multidisciplinary management program could potentially have a beneficial impact on depression and self-esteem in obese young adolescents presenting with a binge-eating disorder. The management program seemed to provide a motivating support system allowing obese young adolescents living in vulnerable neighbourhoods, and their parents, to become involved in their care.

Direct-acting antiviral treatment against hepatitis C virus infection in HIV-Infected patients - "En route for eradication"?

OBJECTIVES

Direct-Acting Antivirals (DAAs) opened a new era in HCV treatment. We report the impact of HCV treatment in French HIV-HCV coinfected patients.

METHODS

All HIV-HCV patients from the Dat'AIDS cohort followed between 2012 and 2015 were included. HCV status was defined yearly as naive, spontaneous cure, sustained virological response (SVR12), failure or reinfection.

RESULTS

Among 32,945 HIV-infected patients, 15.2% were positive for anti-HCV antibodies. From 2012 to 2015, HCV incidence rate increased from 0.35%PY to 0.69%PY in MSM, while median incidence was 0.08%PY in other patients. Median reinfection rate was 2.56%PY in MSM and 0.22%PY in other patients. HCV treatment initiation rate rose from 8.2% in 2012 to 29.6% (48.0% in pre-treated patients vs 22.6% in naïve patients). SVR12 rate increased from 68.7% to 95.2%. By the end of 2015, 62.7% of the patients were cured either spontaneously or following SVR.

CONCLUSIONS

HCV treatment dramatically increased in HIV-HCV patients in France from 2012 to 2015 resulting in HCV cure in nearly two-thirds of the patients in this cohort. Combined with a declining HCV prevalence, the prevalence of active HCV infection among HIV patients will drastically decrease in the forthcoming years.

Opinions toward pain management and palliative care: Comparison between HIV specialists and oncologists

Despite the introduction of HAART, pain is still a common symptom in people living with HIV/AIDS. For these persons, pain management supplied by palliative care teams may support standard HIV care. This study compares opinions toward palliative care of 83 HIV specialists and 217 oncologists (French national survey: Palliative Care 2002). Data were collected by phone questionnaire. A cluster analysis was carried out in order to identify contrasted profiles of opinions toward palliative care. A logistic regression was performed to test the relationships between identified clusters and physicians' characteristics. With a two-cluster partition, we observed a profile corresponding to a restrictive conception of palliative care. Within this profile, physicians were more prone to consider that palliative care should be used only for terminally-ill patients, and only after all curative treatments have failed, with a restrained prescriptive power for physicians providing palliative care. This conception was associated with reluctance toward morphine analgesia. Once controlled for other physicians' characteristics, HIV specialists were more likely than oncologists to endorse this restrictive conception (OR=1.9, CI 95% [1.1; 3.3]). Thus French HIV specialists should be more informed about the utility of providing palliative care, even for patients who are not in terminal stage.

French hospital nurses' opinion about euthanasia and physician-assisted suicide: a national phone survey

BACKGROUND

Hospital nurses are frequently the first care givers to receive a patient's request for euthanasia or physician-assisted suicide (PAS). In France, there is no consensus over which medical practices should be considered euthanasia, and this lack of consensus blurred the debate about euthanasia and PAS legalisation. This study aimed to investigate French hospital nurses' opinions towards both legalisations, including personal conceptions of euthanasia and working conditions and organisation.

METHODS

A phone survey conducted among a random national sample of 1502 French hospital nurses. We studied factors associated with opinions towards euthanasia and PAS, including contextual factors related to hospital units with random-effects logistic models.

RESULTS

Overall, 48% of nurses supported legalisation of euthanasia and 29%, of PAS. Religiosity, training in pallative care/pain management and feeling competent in end-of-life care were negatively correlated with support for legalisation of both euthanasia and PAS, while nurses working at night were more prone to support legalisation of both. The support for legalisation of euthanasia and PAS was also weaker in pain treatment/palliative care and intensive care units, and it was stronger in units not benefiting from interventions of charity/religious workers and in units with more nurses.

CONCLUSIONS

Many French hospital nurses uphold the legalisation of euthanasia and PAS, but these nurses may be the least likely to perform what proponents of legalisation call "good" euthanasia. Improving professional knowledge of palliative care could improve the management of end-of-life situations and help to clarify the debate over euthanasia.

French district nurses' opinions towards euthanasia, involvement in end-of-life care and nurse patient relationship: a national phone survey

OBJECTIVES

To assess French district nurses' opinions towards euthanasia and to study factors associated with these opinions, with emphasis on attitudes towards terminal patients.

DESIGN AND SETTING

An anonymous telephone survey carried out in 2005 among a national random sample of French district nurses.

PARTICIPANTS

District nurses currently delivering home care who have at least 1 year of professional experience. Of 803 district nurses contacted, 602 agreed to participate (response rate 75%).

MAIN OUTCOME MEASURES

Opinion towards the legalisation of euthanasia (on a five-point Likert scale from "strongly agree" to "strongly disagree"), attitudes towards terminal patients (discussing end-of-life issues with them, considering they should be told their prognosis, valuing the role of advance directives and surrogates).

RESULTS

Overall, 65% of the 602 nurses favoured legalising euthanasia. Regarding associated factors, this proportion was higher among those who discuss end-of-life issues with terminal patients (70%), who consider competent patients should always be told their prognosis (81%) and who value the role of advance directives and surrogates in end-of-life decision-making for incompetent patients (68% and 77% respectively). Women and older nurses were less likely to favour legalising euthanasia, as were those who believed in a god who masters their destiny.

CONCLUSIONS

French nurses are more in favour of legalising euthanasia than French physicians; these two populations contrast greatly in the factors associated with this support. Further research is needed to investigate how and to what extent such attitudes may affect nursing practice and emotional well-being in the specific context of end-of-life home care.

Physiological diversity of mitochondrial oxidative phosphorylation

To investigate the physiological diversity in the regulation and control of mitochondrial oxidative phosphorylation, we determined the composition and functional features of the respiratory chain in muscle, heart, liver, kidney, and brain. First, we observed important variations in mitochondrial content and infrastructure via electron micrographs of the different tissue sections. Analyses of respiratory chain enzyme content by Western blot also showed large differences between tissues, in good correlation with the expression level of mitochondrial transcription factor A and the activity of citrate synthase. On the isolated mitochondria, we observed a conserved molar ratio between the respiratory chain complexes and a variable stoichiometry for coenzyme Q and cytochrome c, with typical values of [1-1.5]:[30-135]:[3]:[9-35]:[6.5-7.5] for complex II:coenzyme Q:complex III:cytochrome c:complex IV in the different tissues. The functional analysis revealed important differences in maximal velocities of respiratory chain complexes, with higher values in heart. However, calculation of the catalytic constants showed that brain contained the more active enzyme complexes. Hence, our study demonstrates that, in tissues, oxidative phosphorylation capacity is highly variable and diverse, as determined by different combinations of 1) the mitochondrial content, 2) the amount of respiratory chain complexes, and 3) their intrinsic activity. In all tissues, there was a large excess of enzyme capacity and intermediate substrate concentration, compared with what is required for state 3 respiration. To conclude, we submitted our data to a principal component analysis that revealed three groups of tissues: muscle and heart, brain, and liver and kidney.

Weight-dependent changes of immune system in adipose tissue: importance of leptin

Ancestral lymphoid cells reside in adipose tissues, and their numbers are highly altered in obesity. Leptin, production of which is correlated to fat mass, is strongly involved in the relationships between adipose tissues and immune system. We investigated in epididymal (EPI) and inguinal (ING) fat pads to determine whether 1) lymphocyte phenotypes were correlated to the tissue weight and 2) leptin was involved in such relationships. Immunohistological analyses revealed a tight relationship between the T and NK lymphocytes of the stromal vascular fraction and adipocytes. We identified a significant negative and positive correlation between EPI weight and the percentage of NK and total T cells respectively by cytofluorometric analyses. The NK and ancestral gammadelta T cell contents were directly dependent of leptin since they increased significantly in high-fat (HF) diet mice but not in leptin-deficient (ob/ob) mice as compared to control. By contrast, the alphabeta T cell content seemed independent of leptin because their percentages increased significantly with the EPI weight whatever the type of mice (control, HF, ob/ob). The present study suggests that adipose tissues present, according to their localization, different immunological mechanisms that might be involved in the regulation of adipose cells functions and proliferations.

Individual and combined effects of low oral doses of deoxynivalenol and nivalenol in mice

Deoxynivalenol (DON) and nivalenol (NIV) are toxic Fusarium secondary trichothecene metabolites that often co-occur regularly in cereal grains. These compounds were compared for their toxicity towards C57BL/6 mice on several parameters including alteration in plasma biochemistry, immune system reactivity and hepatic drug metabolism capacity. Mice received individual or combined oral doses of each toxin: 0.071 or 0.355 mg/kg of body weight, administrated three days a week for 4 weeks. Food consumption was altered by the single administration of 0.355 mg/kg of NIV, although no noticeable change of body and organ weights or liver protein contents was detected. NIV administration did cause also significant changes in total CO2 and uric acid concentrations in plasma. Individual toxin exposures led to increases in plasma IgA without no detectable change in the ex vivo production of cytokine by splenocytes. The liver ethoxyresorufin O-deealkylase, pentoxyresorufin O-depenthylase and glutathione S-transferase activities were increased in concert with cytochrome P4501a and P4502b subfamily expression. Administration of combinations of DON and NIV resulted in responses similar to that observed using individual doses of each toxin. However, depending on the ratio of toxin doses and biochemical parameters, some responses could be also additive (plasma IgA and hepatic DCNB conjugation) or synergistic (plasma uric acid).

Adipose tissues as an ancestral immune organ: Site-specific change in obesity

Close relationships have been demonstrated between adipose tissue and the inflammatory/immune system. Furthermore, obesity is increasingly considered as a state of chronic inflammation. Cytofluorometric analysis reveals the presence of significant levels of lymphocytes in the stroma-vascular fraction of white adipose tissues. In epididymal (EPI) fat, lymphocytes display an "ancestral" immune system phenotype (up to 70% of natural killer (NK), gammadelta+ T and NKT cells among all lymphocytes) whereas the inguinal (ING) immune system presents more adaptive characteristics (high levels of alphabeta+ T and B cells). The percentage of NK cells in EPI fat was decreased in obese mice fed with a high-fat diet, whereas gammadelta positive cells were significantly increased in ING fat. These data support the notion that adipose tissue may elaborate immunological mechanisms to regulate its functions which might be altered in obesity.

Impact of Newly Available Drugs on Clinical Progression in Patients with Virological Failure after Exposure to Three Classes of Antiretrovirals

Objective

To study the prognosis of HIV-infected patients with virological failure after exposure to three classes of antiretroviral drugs (ARVs).

Design

Cohort study. Setting: French Hospital Database on HIV.

Patients

Patients previously exposed to at least two nucleoside reverse transcriptase inhibitors (NRTIs), two protease inhibitors and one non-NRTI, with viral load (VL) values of >5000 copies/ml after the exposure criteria were met and a new treatment initiated between 1998 and 2001 with VL >5000 copies/ml.

Main outcome measures

Risk of new AIDS-defining-events (ADEs) or death from first introduction of a drug never used before occurring between 1998 and 2001 defined as baseline.

Results

The main baseline characteristics of the 1092 patients were: previous ADE in 49% of cases, median CD4 cell count 181 μl, median VL 4.9 log10 copies/ml, median duration of ARV therapy 5.0 years and previous exposure to a median of nine ARVs. The crude progression rates were 20.1/100 patient-years among patients included in 1998, 15.1 in 1999, 11.1 in 2000 and 8.6 in 2001. After adjustment for baseline characteristics, the calendar year of inclusion was associated with the risk of clinical progression ( P<0.001). When the types of newly available drugs used at baseline or during follow-up were introduced into the model, year of inclusion was no longer associated with the risk of clinical progression ( P=0.42), while exposure to amprenavir/r, lopinavir/r, abacavir or tenofovir was associated with a lower risk.

Conclusions

The clinical prognosis of heavily pretreated patients experiencing virological failure improved between 1998 and 2001, mainly thanks to the use of newly available drugs with more favourable resistance profiles.

[Doctors' opinions on palliative care: results from a French survey on physicians attitudes and practices]

OBJECTIVE

To examine practitioners' opinions on palliative care.

METHOD

Statistical analyses were carried out on data collected from 1000 physicians recruited to participate in a study on knowledge, attitudes and practices with respect to palliative care ("Palliative Care 2002"). A cluster analysis (CAH) was conducted based on responses to nine questions in order to identify homogeneous and contrasting profiles of opinions on palliative care.

RESULTS

Two distinctly different categories of profiles emerged. The first one had a restrictive approach to palliative care (n = 387; 38.7%), while the second one supported its expansion (n = 613; 61.3%).

CONCLUSION

A newly revised communication campaign which favoured and recognised palliative care could assist in the dissemination of related practices among physicians.

Disclosure of Prognosis to Terminally Ill Patients: Attitudes and Practices Among French Physicians

BACKGROUND

Disclosure of the prognosis to terminally ill patients is a strong prerequisite for integrating the physical, psychological, spiritual, and social aspects of end-of-life care.

OBJECTIVE

This study aimed to assess French physicians' general attitudes and effective practices (with patients followed up to death recently) toward such disclosure.

DESIGN/SUBJECTS

We used data from a cross-sectional survey conducted among a national sample of 917 French general practitioners, oncologists, and neurologists.

RESULTS

A majority of respondents opted for prognosis disclosure only at patients' request, very few opted for systematic disclosure without patient's request, and a significant minority opted for systematic concealment. Concerning deceased patients described by respondents, 44.5% of competent patients were informed of prognosis by their physician, 27.3% were informed by someone else, 9.0% refused to be informed, and 19.2% were simply not informed. Concealment was more frequent for older patients, and physicians involved in a nongovernmental organization (NGO) for patients' support were more likely to disclose the prognosis, even without patient's request.

CONCLUSIONS

Disclosure of the prognosis to terminally ill patients is still far from systematic in France. Further research is needed to better understand the motivations of French physicians' disclosure practices, which are probably culturally shaped.

Biological validation of coenzyme Q redox state by HPLC-EC measurement: relationship between coenzyme Q redox state and coenzyme Q content in rat tissues

The properties of coenzymes Q (CoQ9 and CoQ10) are closely linked to their redox state (CoQox/total CoQ) x 100. In this work, CoQ redox state was biologically validated by high performance liquid chromatography-electrochemical measurement after modulation of mitochondrial electron flow of cultured cells by molecules increasing (rotenone, carbonyl cyanide chlorophenylhydrazone) or decreasing (antimycin) CoQ oxidation. The tissue specificity of CoQ redox state and content were investigated in control and hypoxic rats. In control rats, there was a strong negative linear regression between tissular CoQ redox state and CoQ content. Hypoxia increased CoQ9 redox state and decreased CoQ9 content in a negative linear relationship in the different tissues, except the heart and lung. This result demonstrates that, under conditions of mitochondrial impairment, CoQ redox control is tissue-specific.

[Terminal care of patients by the general practitioner and the specialist. Results of a French survey "Attitudes and practices in palliative treatment--2002"]

OBJECTIVE

Assess the attitude of the practitioners with regard to the management of patients at the end of their lives, depending on the physician/patient communication and treatment of pain. Method Statistical analysis of the data collected among 1,000 practitioners recruited for a survey on knowledge, attitudes and practices regarding palliative care in 2002.

RESULTS

The practitioners who felt "ill at ease" in the management of patients at the end of their life often had a poor opinion regarding morphine and did not systematically their patients of the therapeutic aims.

CONCLUSION

Greater awareness by the practitioners of palliative care would help to improve the quality of care supplied to terminally ill patients.

Phosphotransfer functions mutated Bacillus subtilis HPr-like protein Crh carrying a histidine in the active site

The Bacillus subtilis protein Crh exhibits strong similarity to HPr, a phosphocarrier protein of the phosphoenolpyruvate:sugar phosphotransferase system (PTS). HPr phosphorylated at His-15 can transfer its phosphoryl group to several EIIAs of the PTS for sugar transport and phosphorylation. In addition, it phosphorylates and activates transcriptional regulators containing PTS regulation domains (PRDs). In Gram-positive bacteria, it also controls the enzyme glycerol kinase. Since in Crh the active site His-15 of HPr is replaced with a glutamine, Crh was not able to carry out the catalytic and regulatory functions mediated by P approximately His-HPr. However, when Gln-15 of Crh was replaced with a histidine, Crh gained most of the catalytic and regulatory functions exerted by HPr. To allow CrhQ15H to efficiently phosphorylate and activate the PRD-containing antiterminator LicT, which controls the expression of the bgIS gene and the bgIPH operon, it was sufficient to express the crhQ15H allele under control of the spac promoter in monocopy. By contrast, to phosphorylate and activate glycerol kinase and to allow a ptsH deletion strain (devoid of HPr) to slowly grow on the non-PTS substrate glycerol and to efficiently utilize the PTS sugars glucose and mannitol, the crhQ15H allele had to be expressed from a multicopy plasmid.

Total parenteral nutrition decreases liver oxidative metabolism and antioxidant defenses in healthy rats: comparative effect of dietary olive and soybean oil

BACKGROUND

Total parenteral nutrition (TPN) is used for critically ill patients undergoing surgery, after trauma, or during disease conditions that favor oxidative stress. We studied the effect of TPN on liver oxidative metabolism and antioxidant defenses in rats, and we compared the effect of soybean oil- and olive oil-based diets.

METHODS

Seven-week-old rats (n = 28) were divided into four groups. Two experimental groups received a TPN solution containing soybean oil (TPN-S) or a mixture of olive/soybean oil, 80/20 (TPN-O), IV for 6 days. Orally fed animals received a solid diet including soybean oil (Oral-S) or olive/soybean oil, 80/20 (Oral-O). The following parameters were measured: DL-alpha-tocopherol, vitamin A, malondialdehyde and thiobarbituric acid reactive substances (MDA-TBARS), and total radical-trapping antioxidant parameter (TRAP) in serum; DL-alpha-tocopherol, vitamin A, glutathione (GSH), and catalase (Cat) activity in liver homogenate; fatty acids from phospholipid, cytochrome P-450 content, NADPH-cytochrome c2 reductase activity in liver microsomes; superoxide dismutase (SOD), glutathione peroxidase (Gpx), glutathione reductase (GR), glutathione transferase (GST), and glucose-6-phosphate dehydrogenase (G6PD) in liver cytosol.

RESULTS

The soybean or olive oil diets modified the liver microsomal fatty acid phospholipid composition, but the unsaturation index remained unchanged. TPN specifically increased the saturation of the membrane. The cytochrome P-450 level and the NADPH-cytochrome c2 reductase, SOD, Gpx, Cat, and GST activities were unchanged by soybean oil or olive oil diet but decreased receiving TPN.

CONCLUSIONS

In rats, TPN decreased the liver oxidative metabolism and enzymatic antioxidant defenses. This may be related to saturation of the liver microsomal fatty acids.

Autoregulation of the biosynthesis of the CcpA-like protein, PepR1, in Lactobacillus delbrueckii subsp bulgaricus

PepR1 from Lactobacillus delbrueckii subsp bulgaricus (Lb. bulgaricus) is involved in biosynthesis regulation of the prolidase PepQ. In this paper, we demonstrated that Lb. bulgaricus PepR1 biosynthesis is not constitutive like those of several bacteria but is auto-regulated and depends on the glucose concentration of the culture medium. We propose a model for PepQ regulation by PepR1.

[HIV risk behavior in prison and factors associated with reincarceration of injection drug users]

OBJECTIVES

The aim of this study was to estimate the frequency of risk behavior for HIV transmission in prison and to identify the factors associated with reincarceration.

PATIENTS AND METHODS

An epidemiologic study was carried out in the penitentiary center of Marseilles between December 1995 and March 1997. Five hundred and seventy-four prisoners answered an anonymous voluntary questionnaire managed by independent interviewers.

RESULTS

Among the 574 prisoners, 133 (23%) reported they had injected drugs (intravenous drug users, IDU) including 71 (53%) who had injected drugs during the three months preceding incarceration. Seven percent of the IDU received opiate substitutes before their imprisonment. Nine prisoners of the 120 who have responded to the question (7.5%: 3.7-14.2 95% CI) stated they had injected drugs during the first three months of incarceration. Multivariate analysis showed that reincarceration was significantly more frequent among men, HIV-infected and unemployed prisoners, and prisoners not receiving opiate substitutes at the time of their imprisonment.

DISCUSSION

This study show that risk behaviors of HIV and hepatitis virus transmission are frequent among intravenous drug users, including during their incarceration. The relationship between opiate substitution treatment and reincarceration deserves to be studied further on larger samples in order to better evaluate its impact on social rehabilitation of drug addicts. This data also underline the need to strengthen prevention programs in prisons and the importance of social and health policies targeted on drug users especially opiate substitution programs.

Phosphorylation of HPr by the bifunctional HPr Kinase/P-ser-HPr phosphatase from Lactobacillus casei controls catabolite repression and inducer exclusion but not inducer expulsion

We have cloned and sequenced the Lactobacillus casei hprK gene encoding the bifunctional enzyme HPr kinase/P-Ser-HPr phosphatase (HprK/P). Purified recombinant L. casei HprK/P catalyzes the ATP-dependent phosphorylation of HPr, a phosphocarrier protein of the phosphoenolpyruvate:carbohydrate phosphotransferase system at the regulatory Ser-46 as well as the dephosphorylation of seryl-phosphorylated HPr (P-Ser-HPr). The two opposing activities of HprK/P were regulated by fructose-1,6-bisphosphate, which stimulated HPr phosphorylation, and by inorganic phosphate, which stimulated the P-Ser-HPr phosphatase activity. A mutant producing truncated HprK/P was found to be devoid of both HPr kinase and P-Ser-HPr phosphatase activities. When hprK was inactivated, carbon catabolite repression of N-acetylglucosaminidase disappeared, and the lag phase observed during diauxic growth of the wild-type strain on media containing glucose plus either lactose or maltose was strongly diminished. In addition, inducer exclusion exerted by the presence of glucose on maltose transport in the wild-type strain was abolished in the hprK mutant. However, inducer expulsion of methyl beta-D-thiogalactoside triggered by rapidly metabolizable carbon sources was still operative in ptsH mutants altered at Ser-46 of HPr and the hprK mutant, suggesting that, in contrast to the model proposed for inducer expulsion in gram-positive bacteria, P-Ser-HPr might not be involved in this regulatory process.

The HPr kinase from Bacillus subtilis is a homo-oligomeric enzyme which exhibits strong positive cooperativity for nucleotide and fructose 1,6-bisphosphate binding

Carbon catabolite repression allows bacteria to rapidly alter the expression of catabolic genes in response to the availability of metabolizable carbon sources. In Bacillus subtilis, this phenomenon is controlled by the HPr kinase (HprK) that catalyzes ATP-dependent phosphorylation of either HPr (histidine containing protein) or Crh (catabolite repression HPr) on residue Ser-46. We report here that B. subtilis HprK forms homo-oligomers constituted most likely of eight subunits. Related to this complex structure, the enzyme displays strong positive cooperativity for the binding of its allosteric activator, fructose 1,6-bisphosphate, as evidenced by either kinetics of its phosphorylation activity or the intrinsic fluorescence properties of its unique tryptophan residue, Trp-235. It is further shown that activation of HPr phosphorylation by fructose 1,6-bisphosphate essentially occurs at low ATP and enzyme concentrations. A positive cooperativity was also detected for the binding of natural nucleotides or their 2'(3')-N-methylanthraniloyl derivatives, in either phosphorylation or fluorescence experiments. Most interestingly, quenching of the HprK tryptophan fluorescence by using either iodide or acrylamide revealed a heterogeneity of tryptophan residues within the population of oligomers, suggesting that the enzyme exists in two different conformations. This result suggests a concerted-symmetry model for the catalytic mechanism of positive cooperativity displayed by HprK.

Catabolite regulation of the pta gene as part of carbon flow pathways in Bacillus subtilis

In Bacillus subtilis, the products of the pta and ackA genes, phosphotransacetylase and acetate kinase, play a crucial role in the production of acetate, one of the most abundant by-products of carbon metabolism in this gram-positive bacterium. Although these two enzymes are part of the same pathway, only mutants with inactivated ackA did not grow in the presence of glucose. Inactivation of pta had only a weak inhibitory effect on growth. In contrast to pta and ackA in Escherichia coli, the corresponding B. subtilis genes are not cotranscribed. Expression of the pta gene was increased in the presence of glucose, as has been reported for ackA. The effects of the predicted cis-acting catabolite response element (CRE) located upstream from the promoter and of the trans-acting proteins CcpA, HPr, Crh, and HPr kinase on the catabolite regulation of pta were investigated. As for ackA, glucose activation was abolished in ccpA and hprK mutants and in the ptsH1 crh double mutant. Footprinting experiments demonstrated an interaction between CcpA and the pta CRE sequence, which is almost identical to the proposed CRE consensus sequence. This interaction occurs only in the presence of Ser-46-phosphorylated HPr (HPrSer-P) or Ser-46-phosphorylated Crh (CrhSer-P) and fructose-1,6-bisphosphate (FBP). In addition to CcpA, carbon catabolite activation of the pta gene therefore requires at least two other cofactors, FBP and either HPr or Crh, phosphorylated at Ser-46 by the ATP-dependent Hpr kinase.

Analysis of a ptsH homologue from Streptomyces coelicolor A3(2)

A ptsH homologue of Streptomyces coelicolor A3(2) was identified in the emerging genome sequence, cloned in Escherichia coli and the S. coelicolor HPr over-produced and purified. The protein was phosphorylated in vitro in a phosphoenolpyruvate (PEP)-dependent manner by purified enzyme I (EI) from Bacillus subtilis, and much less efficiently in an ATP-dependent manner by purified HPr kinase, also from B. subtilis. There was no indication of ATP-dependent phosphorylation of the purified protein by cell extracts of either S. coelicolor or Streptomyces lividans. Deletion of the ptsH homologue from the S. coelicolor and S. lividans chromosomes had no effect on growth when fructose was supplied as sole carbon source, and in S. coelicolor it had no effect on glucose repression of agarase and galactokinase synthesis, suggesting that the HPr encoded by this gene does not play an essential role in fructose transport nor a general role in carbon catabolite repression.

Phosphorylation of HPr and Crh by HprK, early steps in the catabolite repression signalling pathway for the Bacillus subtilis levanase operon

Carbon catabolite repression (CCR) of Bacillus subtilis catabolic genes is mediated by CcpA and in part by P-Ser-HPr. For certain operons, Crh, an HPr-like protein, is also implicated in CCR. In this study we demonstrated that in ptsH1 crh1 and hprK mutants, expression of the lev operon was completely relieved from CCR and that both P-Ser-HPr and P-Ser-Crh stimulated the binding of CcpA to the cre sequence of the lev operon.

Phosphorylation of either crh or HPr mediates binding of CcpA to the bacillus subtilis xyn cre and catabolite repression of the xyn operon

Carbon catabolite repression (CCR) of several Bacillus subtilis catabolic genes is mediated by ATP-dependent phosphorylation of Ser46 of the histidine-containing protein (HPr), a phosphocarrier protein of the phosphoenolpyruvate (PEP): sugar phosphotransferase system. A recently discovered HPr-like protein of B. subtilis, Crh, cannot be phosphorylated by PEP and enzyme I but becomes phosphorylated at Ser46 by the ATP-dependent, metabolite-activated HPr kinase. Genetic data suggested that Crh is also implicated in CCR. We here demonstrate that in a ptsH1 crh1 mutant, in which Ser46 of both HPr and Crh is replaced with an alanyl residue, expression of the beta-xylosidase-encoding xynB gene was completely relieved from CCR. No effect on CCR could be observed in strains carrying the crh1 allele, suggesting that under the experimental conditions P-Ser-HPr can substitute for P-Ser-Crh in CCR. By contrast, a ptsH1 mutant was slightly relieved from CCR of xynB, indicating that P-Ser-Crh can substitute only partly for P-Ser-HPr. Mapping experiments allowed us to identify the xyn promoter and a catabolite responsive element (cre) located 229 bp downstream of the transcription start point. Using DNase I footprinting experiments, we could demonstrate that similar to P-Ser-HPr, P-Ser-Crh stimulates binding of CcpA to the xyn cre. Fructose 1,6-bisphosphate was found to strongly enhance binding of the P-Ser-HPr/CcpA and P-Ser-Crh/CcpA complexes to the xyn cre, but had no effect on binding of CcpA alone.

Regulation of the activity of the Bacillus subtilis antiterminator LicT by multiple PEP-dependent, enzyme I- and HPr-catalysed phosphorylation

The transcriptional antiterminator LicT regulates the induction and carbon catabolite repression of the Bacillus subtilis bglPH operon. LicT is inactive in mutants affected in one of the two general components of the phosphoenolpyruvate (PEP):glycose phosphotransferase system, enzyme I or histidine-containing protein (HPr). We demonstrate that LicT becomes phosphorylated in the presence of PEP, enzyme I and HPr. The phosphoryl group transfer between HPr and LicT is reversible. Phosphorylation of LicT with PEP, enzyme I and HPr led to the appearance of three additional LicT bands on polyacrylamide-urea gels. These bands probably correspond to one-, two- and threefold phosphorylated LicT. After phosphorylation of LicT with [32P]-PEP, enzyme I and HPr, proteolytic digestion of [32P]-P-LicT, separation of the peptides by reverse-phase chromatography, mass spectrometry and N-terminal sequencing of radiolabelled peptides, three histidyl residues were found to be phosphorylated in LicT. These three histidyl residues (His-159, His-207 and His-269) are conserved in most members of the BglG/SacY family of transcriptional antiterminators. Phosphorylation of LicT in the presence of serylphosphorylated HPr (P-Ser-HPr) was much slower compared with its phosphorylation in the presence of HPr. The slower phosphorylation in the presence of P-Ser-HPr leading to reduced LicT activity is presumed to play a role in a recently described LicT-mediated CcpA-independent carbon catabolite repression mechanism operative for the bglPH operon.

The hprK gene of Enterococcus faecalis encodes a novel bifunctional enzyme: the HPr kinase/phosphatase

The HPr kinase of Gram-positive bacteria is an ATP-dependent serine protein kinase, which phosphorylates the HPr protein of the bacterial phosphotransferase system (PTS) and is involved in the regulation of carbohydrate metabolism. The hprK gene from Enterococcus faecalis was cloned via polymerase chain reaction (PCR) and sequenced. The deduced amino acid sequence was confirmed by microscale Edman degradation and mass spectrometry combined with collision-induced dissociation of tryptic peptides derived from the HPr kinase of E. faecalis. The gene was overexpressed in Escherichia coli, which does not contain any ATP-dependent HPr kinase or phosphatase activity. The homogeneous recombinant protein exhibits the expected HPr kinase activity as well as a P-Ser-HPr phosphatase activity, which was assumed to be a separate enzyme activity. The bifunctional HPr kinase/phosphatase acts preferentially as a kinase at high ATP levels of 2 mM occurring in glucose-metabolizing Streptococci. At low ATP levels, the enzyme hydrolyses P-Ser-HPr. In addition, high concentrations of phosphate present under starvation conditions inhibit the HPr kinase activity. Thus, a putative function of the enzyme may be to adjust the ratio of HPr and P-Ser-HPr according to the metabolic state of the cell; P-Ser-HPr is involved in carbon catabolite repression and regulates sugar uptake via the phosphotransferase system (PTS). Reinvestigation of the previously described Bacillus subtilis HPr kinase revealed that it also possesses P-Ser-HPr phosphatase activity. However, contrary to the E. faecalis enzyme, ATP alone was not sufficient to switch the phosphatase activity of the B. subtilis enzyme to the kinase activity. A change in activity of the B. subtilis HPr kinase was only observed when fructose-1,6-bisphosphate was also present.

Antagonistic effects of dual PTS-catalysed phosphorylation on the Bacillus subtilis transcriptional activator LevR

LevR, which controls the expression of the levoperon of Bacillus subtilis, is a regulatory protein containing an N-terminal domain similar to the NifA/NtrC transcriptional activator family and a C-terminal domain similar to the regulatory part of bacterial anti-terminators, such as BgIG and LicT. Here, we demonstrate that the activity of LevR is regulated by two phosphoenolpyruvate (PEP)-dependent phosphorylation reactions catalysed by the phosphotransferase system (PTS), a transport system for sugars, polyols and other sugar derivatives. The two general components of the PTS, enzyme I and HPr, and the two soluble, sugar-specific proteins of the lev-PTS, LevD and LevE, form a signal transduction chain allowing the PEP-dependent phosphorylation of LevR, presumably at His-869. This phosphorylation seems to inhibit LevR activity and probably regulates the induction of the lev operon. Mutants in which His-869 of LevR has been replaced with a non-phosphorylatable alanine residue exhibited constitutive expression from the lev promoter, as do levD or levE mutants. In contrast, PEP-dependent phosphorylation of LevR in the presence of only the general components of the PTS, enzyme I and HPr, regulates LevR activity positively. This phosphorylation most probably occurs at His-585. Mutants in which His-585 has been replaced with an alanine had lost stimulation of LevR activity and PEP-dependent phosphorylation by enzyme I and HPr. This second phosphorylation of LevR at His-585 is presumed to play a role in carbon catabolite repression.

New protein kinase and protein phosphatase families mediate signal transduction in bacterial catabolite repression

Carbon catabolite repression (CCR) is the prototype of a signal transduction mechanism. In enteric bacteria, cAMP was considered to be the second messenger in CCR by playing a role reminiscent of its actions in eukaryotic cells. However, recent results suggest that CCR in Escherichia coli is mediated mainly by an inducer exclusion mechanism. In many Gram-positive bacteria, CCR is triggered by fructose-1,6-bisphosphate, which activates HPr kinase, presumed to be one of the most ancient serine protein kinases. We here report cloning of the Bacillus subtilis hprK and hprP genes and characterization of the encoded HPr kinase and P-Ser-HPr phosphatase. P-Ser-HPr phosphatase forms a new family of phosphatases together with bacterial phosphoglycolate phosphatase, yeast glycerol-3-phosphatase, and 2-deoxyglucose-6-phosphate phosphatase whereas HPr kinase represents a new family of protein kinases on its own. It does not contain the domain structure typical for eukaryotic protein kinases. Although up to now the HPr modifying/demodifying enzymes were thought to exist only in Gram-positive bacteria, a sequence comparison revealed that they also are present in several Gram-negative pathogenic bacteria.

The Bacillus subtilis crh gene encodes a HPr-like protein involved in carbon catabolite repression

Carbon catabolite repression (CCR) of several Bacillus subtilis catabolic genes is mediated by ATP-dependent phosphorylation of histidine-containing protein (HPr), a phosphocarrier protein of the phosphoenolpyruvate (PEP): sugar phosphotransferase system. In this study, we report the discovery of a new B. subtilis gene encoding a HPr-like protein, Crh (for catabolite repression HPr), composed of 85 amino acids. Crh exhibits 45% sequence identity with HPr, but the active site His-15 of HPr is replaced with a glutamine in Crh. Crh is therefore not phosphorylated by PEP and enzyme I, but is phosphorylated by ATP and the HPr kinase in the presence of fructose-1,6-bisphosphate. We determined Ser-46 as the site of phosphorylation in Crh by carrying out mass spectrometry with peptides obtained by tryptic digestion or CNBr cleavage. In a B. subtilis ptsH1 mutant strain, synthesis of beta-xylosidase, inositol dehydrogenase, and levanase was only partially relieved from CCR. Additional disruption of the crh gene caused almost complete relief from CCR. In a ptsH1 crh1 mutant, producing HPr and Crh in which Ser-46 is replaced with a nonphosphorylatable alanyl residue, expression of beta-xylosidase was also completely relieved from glucose repression. These results suggest that CCR of certain catabolic operons requires, in addition to CcpA, ATP-dependent phosphorylation of Crh, and HPr at Ser-46.

Cloning and sequencing of two enterococcal glpK genes and regulation of the encoded glycerol kinases by phosphoenolpyruvate-dependent, phosphotransferase system-catalyzed phosphorylation of a single histidyl residue

The glpK genes of Enterococcus casseliflavus and Enterococcus faecalis, encoding glycerol kinase, the key enzyme of glycerol uptake and metabolism in bacteria, have been cloned and sequenced. The translated amino acid sequences exhibit strong homology to the amino acid sequences of other bacterial glycerol kinases. After expression of the enterococcal glpK genes in Escherichia coli, both glycerol kinases were purified and were found to be phosphorylated by enzyme I and the histidine-containing protein of the phosphoenolpyruvate:glycose phosphotransferase system. Phosphoenolpyruvate-dependent phosphorylation caused a 9-fold increase in enzyme activity. The site of phosphorylation in glycerol kinase of E. casseliflavus was determined as His-232. Site-specific mutagenesis was used to replace His-232 in glycerol kinase of E. casseliflavus with an alanyl, glutamate, or arginyl residue. The mutant proteins could no longer be phosphorylated confirming that His-232 of E. casseliflavus glycerol kinase represents the site of phosphorylation. The His232 --> Arg glycerol kinase exhibited an about 3-fold elevated activity compared with wild-type glycerol kinase. Fructose 1,6-bisphosphate was found to inhibit E. casseliflavus glycerol kinase activity. However, neither EIIAGlc from E. coli nor the EIIAGlc domain of Bacillus subtilis had an inhibitory effect on glycerol kinase of E. casseliflavus.

Cooperative and non-cooperative DNA binding modes of catabolite control protein CcpA from Bacillus megaterium result from sensing two different signals

Carbon catabolite repression (CCR) of several operons in Bacillus subtilis and Bacillus megaterium is mediated by the cis-acting cre sequence and trans-acting catabolite control protein (CcpA). We describe purification of CcpA from B. megaterium and its interaction with regulatory sequences from the xyl operon. Specific interaction of CcpA with cre as scored by DNase I footprints at concentrations similar to the in vivo situation requires the presence of effectors. We have found two molecular effectors for CcpA activity, which lead to different recognition modes of DNA. The heat-stable phosphotransfer protein HPr from the PTS sugar uptake system triggers non-cooperative binding of CcpA to cre when phosphorylated at Ser46 (HPr-Ser46-P). Glucose 6-phosphate (Glc-6-P) triggers cooperative binding of CcpA to cre and two auxiliary cre* sites, one of which overlaps the -35 box of the xyl promoter. Binding to cre* depends on the presence of the functional cre sequence. A mutation in cre abolishes carbon catabolite repression in vivo and binding of CcpA to cre and cre* in vitro, indicating looping of the intervening DNA. The two triggers are not simultaneously active. The acidity of the buffer determines which of them activates CcpA when both are present in vitro. Glc-6-P is preferred at pH values below 5.4, and HPr-Ser46-P is preferred at neutral pH. The Ccpa dimers present at neutral pH form tetramers and higher oligomers at pH 4.6, explaining cooperativity of binding to DNA. CcpA is the first member of the LacI/GalR family of regulators, for which oligomerization without the leucine zipper at the C terminus is demonstrated.

Protein phosphorylation chain of a Bacillus subtilis fructose-specific phosphotransferase system and its participation in regulation of the expression of the lev operon

The proteins encoded by the fructose-inducible lev operon of Bacillus subtilis are components of a phosphotransferase system. They transport fructose by a mechanism which couples sugar uptake and phosphoenolpyruvate-dependent sugar phosphorylation. The complex transport system consists of two integral membrane proteins (LevF and LevG) and two soluble, hydrophilic proteins (LevD and LevE). The two soluble proteins from together with the general proteins of the phosphotransferase system, enzyme I and HPr, a protein phosphorylation chain which serves to phosphorylate fructose transported by LevF and LevG. We have synthesized modified LevD and LevE by fusing a His-tag to the N-terminus of each protein allowing rapid and efficient purification of the proteins. We determined His-9 in LevD and His-15 in LevE as the sites of PEP-dependent phosphorylation by isolating single, labeled peptides derived from 32P-labeled LevD, LevD(His)6, and LevE(His)6. The labeled peptides were subsequently analyzed by amino acid sequencing and mass spectroscopy. Mutations replacing the phosphorylatable histidyl residue in LevD with an alanyl residue and in LevE with a glutamate or aspartate were introduced in the levD and levE genes. These mutations caused strongly reduced fructose uptake via the lev-PTS. The mutant proteins were synthesized with a N-terminal His-tag and purified. Mutant LevD(His)6 was very slowly phosphorylated, whereas mutant LevE(His)6 was not phosphorylated at all. The corresponding levD and levE alleles were incorporated into the chromosome of a B. subtilis strain expressing the lacZ gene under control of the lev promoter. The mutations affecting the site of phosphorylation in either LevD or LevE were found to cause constitutive expression from the lev promoter of B. subtilis.