Attitudes of primary care physicians towards bariatric surgery in Switzerland – a free-word association networks analysis

Objective

Primary care physicians (PCP) have a major responsibility in identifying patients with obesity eligible for bariatric surgery (BS). The aim was to explore PCPs’ attitudes towards BS in order to map potential barriers of referral.

Methods

3526 PCPs in Switzerland were invited to participate in an online survey. PCPs were asked to write the first 5 words coming to their mind about the term “bariatric surgery”. Additionally, they had to pick 2 emotions that best described each provided association. Demographic data and obesity-related referral patterns were collected. Cognitive representation network was constructed based on co-occurrence of associations, using validated data-driven methodology.

Results

216 PCPs completed the study. Respondents were aged 55±9.8 years, had an equal gender distribution and practiced mainly in urban setting (Table 1). The majority of PCPs refer either often (31%) or sometimes (41%) patients for BS, while 7% never refer patients to BS, even if eligibility criteria are met. The PCPs’ overall satisfaction with BS was high (88.5%)(Fig. 1). PCPs could be categorized in 3 subgroups based on their cognitive representation of BS: a) indication-focused (most frequent associations: “obesity”, ”diabetes”/most frequent emotion: “worrying”), b) treatment-focused (“gastric bypass”, “weight loss”/“interested”), and c) risk vs. benefit-focused (“complications”, “challenging follow-up”, “success”/“alert”) (Fig. 2&3). There were no relevant demographic or practice related differences between PCPs in the 3 cognitive modules. PCPs with a treatment-focused mindset had a significantly better knowledge of current guidelines on indications of BS (χ2=17.1, P=0.029) and referred in average 5 patients/year, x2 more than PCPs belonging to the other cognitive modules.

Conclusion

PCPs in Switzerland approve the efficacy of BS, but show reservation to refer eligible patients systematically. PCPs think about BS along 3 cognitive schemes, and the treatment-focused attitude was coupled with the highest willingness to refer eligible patients for BS. Confident knowledge of current indications of BS was the only significant factor that distinguished PCPs with a treatment-focused attitude. Strengthening the collaboration in therapeutic decision-making between PCPs and BS centers has the potential to improve access to optimal care for patients with obesity.

HMGB1 promotes CXCL12-dependent egress of murine B cells from Peyer's patches in homeostasis

High mobility group box-1 protein (HMGB1) is an alarmin that, once released, promotes inflammatory responses, alone and as a complex with the chemokine CXCL12. Here, we report that the HMGB1-CXCL12 complex plays an essential role also in homeostasis by controlling the migration of B lymphocytes. We show that extracellular HMGB1 is critical for the CXCL12-dependent egress of B cells from the Peyer's patches (PP). This promigratory function of the complex was restricted to the PPs, since HMGB1 was not required for B-cell migratory processes in other locations. Accordingly, we detected higher constitutive levels of the HMGB1-CXCL12 complex in PPs than in other lymphoid organs. HMGB1-CXCL12 in vivo inhibition was associated with a reduced basal IgA production in the gut. Collectively, our results demonstrate a role for the HMGB1-CXCL12 complex in orchestrating B-cell trafficking in homeostasis, and provide a novel target to control lymphocyte migration in mucosal immunity.

Defining global benchmarks in elective secondary bariatric surgery comprising conversional, revisional and reversal procedures

Objective

Management of poor response and of long-term complications after bariatric surgery (BS) is complex and under-investigated. Indications and types of reoperations vary widely and postoperative complication rates are higher compared to primary BS. Benchmarking uses best performance in a given field as reference point for improvement. Our aim was to define ‘‘best possible’’ outcomes for elective secondary BS.

Methods

The establishment of benchmarks in secondary BS followed a standardized methodology, based on recommendations of a Delphi consensus panel of experts. This multicenter study analyzed patients undergoing elective secondary BS in 18 high-volume centers on 4 continents from 06/2013 to 05/2019. Twenty-one outcome benchmarks were established in low-risk patients, defined as the 75th percentile of the median outcome values of the centers. Benchmark cases had no: previous laparotomy, diabetes, sleep apnea, cardiopathy, renal insufficiency, inflammatory bowel disease, immunosuppression, history of thromboembolic events, BMI>50kg/m2 or age>65 years. Descriptive statistics, multivariate logistic regression and data visualization were performed using the R software.

Results

Out of 44’884 elective bariatric procedures performed in the participating centers, 5’328 secondary BS cases were identified. The benchmark cohort included 3143 cases, mainly females (85%), aged 43.8±10 years, 8.4±5.3 years after primary BS, with a body mass index 35.2±7kg/m2. Main indications were insufficient weight loss (43%) and gastro-esophageal reflux disease/dysphagia (25%). 90-days postoperatively, 14.57% of benchmark patients presented ≥1 complication, mortality was 0.06% (n = 2). Significantly higher morbidity was observed in non-benchmark cases (OR 1.36) and after conversional or revisional procedures with gastrointestinal suture/stapling (OR 1.7). Benchmark cutoffs at 90-days postoperatively were ≤5.8% re-intervention and ≤8.8% re-operation rate. At 2-years (IQR 1-3) 15.6% of benchmark patients required a reoperation.

Conclusion

Secondary BS is safe, although postoperative morbidity exceeds the established benchmarks for primary BS. The excess morbidity is due to an increased risk of gastrointestinal leakage and higher need for intensive care. The considerable rate of tertiary BS warrants expertise and future research to optimize the management of non-success after BS.

Relationship between blood magnesium and psychomotor retardation in drug-free patients with major depression

In previous reports, we have observed that blood magnesium was significantly higher in drug-free patients with major depression when compared to healthy controls. This was especially true for erythrocyte magnesium. Furthermore, the most severely depressed patients had the highest intracellular magnesium content, showing that intracellular magnesium rate was related to the intensity of symptoms. We report here the results of blood magnesium measured in 88 major depressed patients as compared to 61 controls. We show that the mean erythrocyte and also plasma magnesium contents are both increased in these patients. We observe that about 40% of male and female patients have a very significant increase (25%) in intracellular magnesium content as compared to controls. However, about 60% of the hospitalised depressed patients have normal values. None of the controls has high erythrocyte magnesium. This is less evident concerning the plasma magnesium. No differences are observed between patients when classified according to the intensity of moral pain or anxiety. In contrast, the patients with mild to high psychomotor retardation score, which is an index of hypoexcitability, have significant higher erythrocyte magnesium values compared with other patients. The results of male patients without psychomotor retardation do not differ from control values. Our study suggests that central hypoexcitability might be related to an increase in intracellular magnesium observed at the peripheral level, keeping in mind that hyperexcitability, as observed in various conditions such as stress and cardiovascular disorders, is frequently associated, in contrast, with a decrease in blood magnesium.

Does cartoon movie distraction decrease burned children's pain behavior?

The purpose of this study was to evaluate cartoon movie viewing as a practical and low-cost intervention to decrease burned children's pain behavior during dressing changes. Thirteen children, 4 to 12 years of age, with a mean TBSA burn of 7.9% were assessed using a reversal, single-subject experimental design. The experimental condition consisted of the presentation of a cartoon movie as a nonpharmacologic intervention in conjunction with a standardized analgesic medication. In the control condition children's pain was treated with the standardized analgesic medication only. Behavioral distress was measured during the first six dressing changes postburn with the Observational Scale of Behavioral Distress. No significant effect of cartoon movie distraction on observed behavioral distress in patients was found. Interrater reliability of the Observational Scale of Behavioral Distress was good (kappa =.87-.98). Wound debridement was found to be the most painful part of the dressing change. A simple, easily applicable, and low-cost distraction intervention such as presenting cartoon movies does not seem to be sufficiently powerful to measurably reduce burned children's distress during dressing changes. Findings are based on purely observational data. Inclusion of self-report measures in future studies might reveal intervention effects on anxiety and subjective pain perception.

Magnesium involvement in sleep: genetic and nutritional models

Alterations of peripheral magnesium (Mg) concentration have been reported in association with several behavioral disorders and sleep organization. Blood Mg regulation is under a strong genetic control, whereas brain Mg regulation does not seem to be affected. We have studied peripheral and central levels of Mg and analyzed sleep in two lines of mice selected for low (MGL) and high (MGH) red blood cell (RBC) Mg levels. The same variables were also studied in C57BL/6J mice before and after 3 weeks of Mg deficiency. Whereas blood Mg was highly affected by the selection, brain Mg exhibited only small differences between the two lines. In contrast, Mg deficiency strongly decreased both central and peripheral Mg levels. Sleep analysis indicated that in both models the amount of paradoxical sleep was lower in mice with higher Mg levels. The amplitude of daily variation in sleep and slow-wave sleep delta power was markedly decreased in MGH line. Quantitative electroencephalogram (EEG) analysis also revealed a faster theta peak frequency in MGH mice, irrespective of behavioral states. Central Mg showed significant correlations with the amount of paradoxical sleep and sleep consolidation. However, because the direction of these correlations was not consistent, it is concluded that optimal, (physiological) rather than high or low, Mg levels are needed for normal sleep regulation.

Blood and brain magnesium in inbred mice and their correlation with sleep quality

A strong genetic component in the regulation of blood magnesium (Mg) levels has been demonstrated. The regulation and distribution of brain Mg levels, however, have never been assessed. Herein we report on the genetic variation of peripheral and central Mg levels in six inbred strains of mice. In addition, the possible involvement of Mg in sleep regulation was assessed by establishing correlations between Mg and sleep parameters obtained before and after a 6-h sleep deprivation. Although genotype strongly determined blood Mg levels, it did not affect brain Mg, suggesting that central and peripheral Mg are regulated differently. Central Mg displayed a highly structure-specific distribution with frontal cortex having the highest and brain stem the lowest values. Whereas for the amount and distribution of baseline sleep only marginal correlations with Mg were found, Mg contents in four of nine brain structures were highly positively correlated with the length of slow-wave sleep episodes during recovery. This relationship suggests that higher levels of Mg in specific brain sites promote sleep quality as part of a recovery process.

Are preventive HIV interventions at airports effective?

BACKGROUND

Few empirical data exist on the impact of preventive human immunodeficiency virus (HIV) interventions on intended and actual sexual behavior of international tourists. The present cross-sectional study is based on a 2 3 2 design.

METHODS

The sample consisted of departing and arriving passengers (n = 3100) at Zurich Airport with destinations in countries where heterosexual HIV transmission is dominant. While 41% of the tourists obtained information about safer sex, the remaining 59% without such intervention served as control group. Departing passengers completed a short questionnaire focusing on their planned sexual behavior. Arriving passengers were asked about their actual behavior during the journey. Subjects of the intervention group also evaluated the impact of the consultation.

RESULTS

Most travelers appreciated the intervention and reported that they received important information. Members of the intervention group were better informed than those of the control group about the risk of heterosexually transmitted HIV infection (p <.01). They also indicated more often that they could imagine having casual sex abroad (23% vs 16%, p <.01). However, the two groups did not differ with regard to planned condom use or actual sexual behavior. Whereas most of departing passengers indicated that they would use condoms consistently, only half of the passengers who reported casual sex actually did so. Subjects who refused to participate in the intervention tended to consider it as irrelevant and reported less consistent condom use.

CONCLUSIONS

Although travel health interventions focusing on casual sex are appreciated and increase the knowledge, they failed to result in significant behavior modification. Future projects should attempt to approach possible risk groups more specifically and to have more impact.

Weak association between blood sodium, potassium, and calcium and intensity of symptoms in major depressed patients

In previous reports, we showed that plasma and erythrocyte magnesium were increased in many drug-free hospitalized depressed patients. Furthermore, we observed that erythrocyte magnesium content was related to the intensity of the symptoms. Highly depressed patients had the highest magnesium values. Today, we report the results of plasma and erythrocyte sodium and potassium, and of total and ultrafilterable plasma calcium in 66 hospitalized patients with major depression compared to 58 healthy controls. No consistent differences in these biochemical parameters are observed between patients when separated according to intensity of anxiety, psychomotor retardation, and moral distress. Plasma sodium is higher and plasma potassium lower in female patients of all subgroups as compared to controls. Both male patients and controls have erythrocyte sodium and potassium levels that are significantly different from those of females. This clearly suggests a separation into genders in such studies. In conclusion--in contrast to blood magnesium--sodium, potassium, and calcium levels do not seem to be related to the intensity of the main clinical symptoms in hospitalized patients with major depression.

Regulation of 5'-AMP-activated protein kinase activity by the noncatalytic beta and gamma subunits

The mammalian 5'-AMP-activated protein kinase is a heterotrimer consisting of an alpha catalytic subunit and beta and gamma noncatalytic subunits, each of which is represented in a larger isoprotein family, related to the SNF1 kinase and its interacting proteins in yeast. In this study, we have used mammalian cell transfection to compare the activities of the two alpha subunit isoforms, alpha-1 and alpha-2, and to study the influence of the noncatalytic subunits on enzyme subunit association and activity. Expression of epitope-tagged protein subunits in COS7 cells indicates detectable but low level kinase activity for each of the two catalytic alpha subunits. Co-expression of alpha subunits with the beta or gamma subunits modestly increases kinase activity accompanied by the formation of alpha/beta or alpha/gamma heterodimers. Co-expression of all three subunits, however, is accompanied by a 50-110-fold increase in kinase activity with the formation of a heterotrimeric complex. In addition to binding of each noncatalytic subunit to the alpha subunit, the beta and gamma subunits bind to each other, likely resulting in a more stable heterotrimeric complex. The increase in kinase activity associated with expression of this heterotrimer is due both to an increase in enzyme-specific activity (units/enzyme mass) and to an apparent enhanced alpha subunit expression. Co-expression of a catalytically defective alpha subunit or the beta/gamma-binding COOH-terminal domain of the alpha subunit results in reduced heterotrimeric kinase activity. The synergistic positive regulatory roles for both the noncatalytic beta and gamma subunits of 5'-AMP-activated protein kinase contrasts with the Snf1p kinase, where only heterodimers of Snf1p and Snf4p seem to be required for maximum kinase activity.

Identification of a second human acetyl-CoA carboxylase gene

Acetyl-CoA carboxylase (ACC), an important enzyme in fatty acid biosynthesis and a regulator of fatty acid oxidation, is present in at least two isoenzymic forms in rat and human tissues. Previous work has established the existence of a 265,000 Da enzyme in both the rat and human (RACC265; HACC265) and a higher-molecular-mass species (275,000-280,000 Da) in the same species (RACC280; HACC275). An HACC265 gene has previously been localized to chromosome 17. In the present study, we report cloning of a partial-length human cDNA sequence which appears to correspond to HACC275 and its rat homologue, RACC280, as judged by mRNA tissue distribution and cell-specific regulation of mRNA/protein expression. The gene encoding this isoenzymic form of ACC has been localized to the long arm of human chromosome 12. Thus, ACC is represented in a multigene family in both rodents and humans. The newly discovered human gene and its rat homologue appear to be under different regulatory control to the HACC265 gene, as judged by tissue-specific expression in vivo and by independent modulation in cultured cells in vitro.

Non-catalytic beta- and gamma-subunit isoforms of the 5'-AMP-activated protein kinase

The mammalian 5'-AMP-activated protein kinase (AMPK) is a heterotrimeric protein consisting of alpha-, beta-, and gamma-subunits. The alpha-subunit is the catalytic subunit and is related to the yeast Snf1p kinase. In this study, we report the cloning of full-length cDNAs for the non-catalytic beta- and gamma-subunits. The rat liver AMPK beta-subunit clone predicts a protein of 30,464 Da, which is related to the Sip1p, Sip2p, and Gal83p subfamily of yeast proteins that interact with Snf1p and are involved in glucose regulation of gene expression. The AMPK beta-subunit, when expressed in bacteria and in mammalian cells, migrates anomalously on SDS gels at an apparent molecular mass of 40 kDa. Rat and human liver AMPK gamma-subunit clones predict a protein of 37,577 Da (AMPK-gamma1), which is related to the yeast Snf4p protein that copurifies with Snf1p and to a larger family of other human AMPK gamma-isoforms. The mRNAs for both AMPK- beta and AMPK-gamma1 are widely expressed in rat tissues, consistent with a broad role for AMPK in cellular regulation. These data reveal a mammalian multisubunit protein kinase strikingly similar to the multisubunit glucose-sensing Snf1 kinase complex. The identification of isoform families for the AMPK subunits indicates the potential diversity of the roles of this highly conserved signaling system in nutrient regulation and utilization in mammalian cells.

Mammalian AMP-activated protein kinase subfamily

The mammalian 5'-AMP-activated protein kinase (AMPK) is related to a growing family of protein kinases in yeast and plants that are regulated by nutritional stress. We find the most prominent expressed form of the hepatic AMPK catalytic subunit (alpha 1) is distinct from the previously cloned kinase subunit (alpha 2). The alpha 1 (548 residues) and alpha 2 (552 residues) isoforms have 90% amino acid sequence identity within the catalytic core but only 61% identity elsewhere. The tissue distribution of the AMPK activity most closely parallels the low abundance 6-kilobase alpha 1 mRNA distribution and the alpha 1 immunoreactivity rather than alpha 2, with substantial amounts in kidney, liver, lung, heart, and brain. Both alpha 1 and alpha 2 isoforms are stimulated by AMP and contain noncatalytic beta and gamma subunits. The liver alpha 1 isoform accounts for approximately 94% of the enzyme activity measured using the SAMS peptide substrate. The tissue distribution of the alpha 2 immunoreactivity parallels the alpha 2 8.5-kilobase mRNA and is most prominent in skeletal muscle, heart, and liver. Isoforms of the beta and gamma subunits present in the human genome sequence reveal that the AMPK consists of a family of isoenzymes.

Relationship between erythrocyte magnesium, plasma electrolytes and cortisol, and intensity of symptoms in major depressed patients

53 male and female drug-free major depressed patients were separated into three groups according to the severity of the depression. In the entire regrouped population, plasma and erythrocyte magnesium (Mg) were shown to increase as compared with 48 healthy controls, confirming our previous studies. The middle and highly depressed patients had higher erythrocyte and also plasma Mg levels than either lowly depressed patients or controls. Only, a few differences were noticed in plasma sodium, potassium and calcium (Ca) in the three groups of patients, except for ultrafiltrable plasma Ca, measured for the first time in affective disorders. Thus, erythrocyte and also plasma Mg are shown to be associated with the intensity of the depression. As blood hypomagnaesemia is often related to hyperexcitability, further investigations are actually in process to shown whether hypermagnesaemia might be, in contrast, associated with psychomotor retardation as observed in many depressed patients.

Catalytic subunits of the porcine and rat 5'-AMP-activated protein kinase are members of the SNF1 protein kinase family

The 5'-AMP-activated protein kinase (AMPK) regulates the fatty acid and sterol synthesizing pathways via phosphorylation of acetyl-CoA carboxylase and HMG-CoA reductase, respectively. Highly purified kinase from porcine liver contains three apparent subunits of molecular mass 63 kDa, 40 kDa and 38 kDa. Peptide sequencing of the 63 kDa protein (AMPK63cat) revealed that this polypeptide is the catalytic subunit of the kinase. Porcine peptide sequences were used to clone by RT-PCR partial length cDNAs for the catalytic domains of the porcine AMPK63cat, and its rat homolog, which were virtually identical in deduced amino acid sequence. Screening of a rat liver cDNA library with these partial length cDNAs and with degenerate oligonucleotides yielded several unique clones, some of which had a 142 bp deletion in the catalytic domain of the kinase. A consensus full-length sequence with a 1.7 kb open reading frame has been constructed from overlapping library and PCR-derived clones. A large mRNA for rat AMPK63cat (8.5 kb) is expressed in nearly all rat tissues, with highest levels detectable in heart and skeletal muscle. Using PCR, the presence of two mRNA species with or without the 142 bp deletion in the catalytic domain was noted in all rat tissues examined. Comparison of the deduced protein sequence of AMPK63cat reveals highly conserved homologies in both the catalytic and non-catalytic domains to several members of the SNF1 kinase family, including kinases from Arabidopsis, barley, rye, and S. cerevesiae, as well as to other mammalian kinases and to a C. elegans kinase. The high evolutionary conservation of both kinase structure and function (metabolite sensing) coupled with their pattern of tissue/organism expression suggest that the mammalian members of this kinase family likely play wider roles than the regulation of cellular lipid metabolism.

Sodium-magnesium exchange in erythrocyte membranes from patients with affective disorders

The Vmax of erythrocyte sodium-magnesium exchange was measured for the first time in 63 patients suffering from affective disorders and compared to that in 33 healthy subjects. Depressed patients had a significantly higher Vmax (215 +/- 13 vs. 151 +/- 14 mumol/l.cells/h; p < 0.005; mean +/- SEM). This tendency was conserved after division of the 63 patients into three clinical subgroups according to the DSM-III-R criteria. Thirty-four patients from this panel were divided into three subgroups according to the chemical class of the antidepressant drug used and were followed up during a 3-month period of drug treatment. Mood improvement over the 3-month period was associated with a slow increase in Vmax of Na/Mg exchange (delta increase approximately 25 mumol/l.cells/h), except in the subgroup of patients treated with non-tricyclic antidepressants (n = 8). These results are consistent with the previously reported link between high erythrocyte magnesium content and affective disorders. Indeed, enhanced Na/Mg exchange Vmax, which probably results from an increased number of transport units per cell, contributes to the normalization of red blood cell magnesium content correlated with mood improvement.

Mammalian 5'-AMP-activated protein kinase non-catalytic subunits are homologs of proteins that interact with yeast Snf1 protein kinase

The 5'-AMP-activated protein kinase is responsible for the regulation of fatty acid synthesis by phosphorylation and inactivation of acetyl-CoA carboxylase. The porcine liver 5'-AMP-activated protein kinase 63-kDa catalytic subunit co-purifies 14,000-fold with a 38- and 40-kDa protein (Mitchelhill, K.I. et al. (1994) J. Biol. Chem. 269, 2361-2364). The 63-kDa subunit is homologous to the Saccharomyces cerevisiae Snf1 protein kinase, which regulates gene expression during glucose derepression. Peptide amino acid and polymerase chain reaction-derived partial cDNA sequences of both the pig and rat liver enzymes show that the 38-kDa protein is homologous to Snf4p (CAT3) and that the 40-kDa protein is homologous to the Sip1p/Spm/GAL83 family of Snf1p interacting proteins. Sucrose density gradient and cross-linking experiments with purified 5'-AMP-activated protein kinase suggest that both the 38- and 40-kDa proteins associate tightly with the 63-kDa catalytic polypeptide in either a heterotrimeric complex or in dimeric complexes. The 40-kDa subunit is autophosphorylated within the 63-kDa subunit complex. The sequence relationships between the mammalian 5'-AMP-activated protein kinase and yeast Snf1p extend to the subunit proteins consistent with conservation of the functional roles of these polypeptides in cellular regulation by this family of metabolite-sensing protein kinases.

Platelet serotonin and plasma tryptophan in depressed patients: effect of drug treatment and clinical outcome

Platelet serotonin and plasma tryptophan were studied in healthy subjects and in depressed patients before and during their antidepressant drug treatment. Before treatment, mean platelet serotonin level was normal in depressed patients compared with healthy subjects while a significant decrease in patients' plasma TRP was noted (t = 6.0, p < .001). The concentrations of platelet 5-HT level did not correlate with either plasma TRP or with clinical variables, that is, AMDP depression and AMDP anxiety scores. Antidepressant drugs treatment decreased platelet 5-HT level (ANOVA F = 8.27, p < .001) whatever the clinical outcome of the patient, whereas the changes observed in plasma TRP were positively related to the mood state change. These results suggest that platelet serotonin could be a good pharmacological model but has no relevance concerning the mood state.

Identification of human acetyl-CoA carboxylase isozymes in tissue and in breast cancer cells

1. In the rat, acetyl-CoA carboxylase (ACC), a rate-limiting enzyme in fatty acid metabolism, exists as at least two different isozymes (M(r) 265,000 and 280,000) that display distinct tissue-specific distribution and regulation. 2. Based on the study of human tissue and human-derived breast cancer cell lines by enzyme isolation and protein blotting techniques, we have now identified two human isoforms of M(r) 265,000 (HACC 265) and 275,000 (HACC 275), each of which is homologous to one of the rat isozymes. 3. Human breast carcinoma cell lines show variable expression of these two isoforms, mirrored in the estimation of ACC acetyl-CoA kinetics.

[7 years study of erythrocyte membrane transport of monoamine precursors. 395 patients (335 depressed, 60 schizophrenic patients)]

According to the monoaminergic hypothesis of affective and schizophrenic syndromes, a perturbation of influx of precursors of monoamines such as tyrosine (TYR) and tryptophan (TRYP) into the brain might be correlated with the clinical syndromes. The measure of blood cell membrane transports of TYR and TRYP is an interesting peripheral model for the study of these syndromes. This work concerns 395 patients (335 depressed and 60 schizophrenics); 215 of depressed patients were followed after the antidepressant therapy. The transport of TYR and TRYP into erythrocytes was measured as followed: erythrocytes were incubated in plasma for 10 min. at 0 degree and 37 degrees C with radiolabeled TYR and TRYP; facilitated diffusion was calculated by subtracting from the total amount of radioactivity taken up by the cells at 37 degrees C (total uptake) that accumulated at 0 degree C (passive diffusion). The results showed that: 1) The depressive syndromes were characterised by a decrease of facilitated diffusion of TYR, an increase of facilitated diffusion of TRYP and a decrease of the index diffusion of TYR/TRYP. 2) The means of variables were different according to the diagnostic sub-groups (DSM III). In the depressions with alcoholism, the facilitated diffusions were increased compared to depressive syndromes without others diagnosis. The depressions with dementia were in intermediate position. 3) After treatment with antidepressant drugs, the biological variables improved with the clinical improvement, without complete normalization compared to controls. The patients without clinical improvement showed no change in the biological measures. 4) Patients for whom the choice of antidepressant drug was done according to the facilitated diffusions showed a 87% rate of clinical improvement, while this rate was 60% in the other patients. 5) In schizophrenic patients, the biological variables were different than in depressed or normal controls and showed a little decrease of facilitated diffusion of TYR, a marked decrease of diffusion of TRYP and an increased index of diffusion TYR/TRYP.

Skin irritant reactivity following experimental cumulative irritant contact dermatitis

Despite the frequency of irritant contact dermatitis, very little is known about the duration of barrier function impairment following cumulative irritant contact dermatitis. We studied post-irritation irritant reactivity by assessing the response to SLS irritation in previously irritated sites. Cumulative irritant contact dermatitis was induced on the forearms of 15 volunteers aged 18 to 50 years by repeated occluded application of 0.5% SLS 1 h per day over 3 weeks. 3, 6 and 9 weeks later, previously irritated and unirritated control sites were challenged with 2% SLS under occlusion for 23 h. Irritation was assessed by visual scoring, transepidermal water loss (TEWL) as an indicator of epidermal barrier function, and capacitance as a parameter of epidermal water content. While no difference in irritant reactivity between pre-irritated and unirritated sites was observed 3 weeks following irritant contact dermatitis, there was a significant hyporeactivity of previously irritated skin as expressed by clinical scores, TEWL and capacitance at 6 and 9 weeks. Our results indicate that epidermal barrier function remains altered even 9 weeks after cumulative irritant contact dermatitis. With regard to patch testing, post-irritation hyporeactivity might be a cause of false-negative tests on previously irritated sites.

Application of dual-digitonin-pulse perfusion to the study of hepatic mRNA zonation

Heterogeneous zonation of hepatic protein expression over the liver lobule has been recognized by using several analytical techniques, including microdissection, selective cell isolation, immunohistochemistry and hybridization of mRNA in situ. We previously employed the technique of dual-digitonin-pulse perfusion for the highly selective collection and analysis of periportal and perivenous soluble protein. In the present work we have now documented the feasibility of the application of this technique to the study of zonal distribution of mRNA. By using a split-stream design, both protein and RNA fractions can be simultaneously collected from hepatic zones. High-quality RNA (average yield approximately 9-33 micrograms of total RNA per mg of eluted protein) is obtained for analysis. As analysed by immunoblotting and Northern-blot analysis, the zonal distribution of several important cytosolic metabolic enzymes and their mRNAs can be documented. This technique is also applicable to the study of mRNAs for organelle- and membrane-associated proteins that are not recoverable with this digitonin-lysis technique. The application of this experimental technique should allow further molecular insight into the mechanisms underlying zonation of hepatic function.

Brain acetyl-CoA carboxylase: isozymic identification and studies of its regulation during development and altered nutrition

Acetyl-CoA carboxylase, the rate-limiting enzyme of fatty acid synthesis, exists as an oligodendrocyte-associated enzyme in brain and plays an important role in supplying fatty acid for myelination. Rat brain acetyl-CoA carboxylase (ACC) has been identified as a single isozyme of M(r) = 265,000 daltons, indistinguishable immunologically from the isozyme in rat adipose tissue and liver. Total activity of brain ACC declines from birth to 4 weeks of age in the newborn rat. This change in activity can entirely be accounted for by changes in enzyme content, not enzyme specific activity, and is paralleled by decreases in ACC mRNA. In contrast, cardiac, skeletal muscle and liver ACC does not change in content over this developmental period. Unlike ACC in liver and adipose tissue, the enzyme content and specific activity of brain ACC is invariant during various states of nutrition. These data indicate that the brain ACC is subject to unique regulation, as compared to non-neural enzyme. The mechanisms underlying the control of neural ACC activity may be important to understanding the process of myelination during development and to a more general understanding of the factors regulating ACC expression/activity in other tissues.

Blood magnesium, potassium, sodium, calcium and cortisol in drug-free depressed patients

Many biochemical variables, including plasma and erythrocyte magnesium, were simultaneously measured in drug-free depressed patients (n = 34), compared to healthy controls (n = 35). Higher plasma and erythrocyte magnesium concentrations were observed in patients than in controls (+12 per cent, P < 0.0001 and 14 per cent, P < 0.0001, respectively). In contrast, patients showed a lower plasma potassium level (-10 per cent; P < 0.007). Cortisol secretion was much higher in patients (+35 per cent; P < 0.02), particularly in females, showing overactivity of the hypothalamo-hypophyseo-adrenal axis in the patients. Except in a few cases, plasma sodium and calcium in patients did not differ from control values. Significant differences in magnesium and cortisol levels were observed between patients classified in diagnostic groups and by sex, whereas little variation in the other biochemical indices was noted. The increase in blood magnesaemia and its possible association with central hypocatecholaminergic deficiency in affective disorders are discussed.

[Erythrocyte membrane transport of amino acid precursors of monoamines in schizophrenic patients. Comparison with depressive patients]

The study concerned 72 schizophrenic and 200 depressed patients hospitalised between 1983 and 1990. The erythrocyte membrane transports (EMT) of L-tyrosine and L-tryptophan (at 37 degrees, 0 degrees and 37-0 degrees) of schizophrenics without treatment nor depression were different compared to controls and depressed patients. The schizophrenics under neuroleptic treatment and/or depressed showed same means of EMT values as depressed patients. The slopes of the correlations between EMT of tyrosine or tryptophan at 37 degrees, 0 degrees and 37-0 degrees, as well as that between plasma levels of these amino acids, were parallel. However the slopes of the correlations between EMT of tyrosine and tryptophan were different according to the subgroups of patients: the perturbations of EMT were related to the clinical characteristics. In depressed patients and in schizophrenic patients under neuroleptic treatment and/or depressed, little changes in EMT of tyrosine were related to high changes of EMT of tryptophan.

Platelet membrane alpha 2-adrenergic receptors in depression

The platelet membrane was used as a model system to examine alpha 2-adrenergic receptors in 30 depressed patients and 30 healthy control subjects. The number of binding sites and their affinity for 3H-UK 14304 (5-bromo-6-(2-imidazoline-2-ylamino)-quinoxaline), a potent, highly selective alpha 2-adrenergic receptor agonist, was measured. Plasma magnesium and free 3-methoxy-4-hydroxyphenylglycol (MHPG) concentrations were assayed in the same sample. A decreased agonist-receptor affinity was found in depressed patients, whereas receptor density was not significantly altered compared with that in control subjects. In bipolar depressed and dysthymic patients, there was a tendency toward a higher density of alpha 2-adrenergic receptors. This trend was not apparent in unipolar, recurrent depressed subjects. Moreover, a positive correlation between Bmax and Kd values was observed in patients but not in control subjects--a finding that suggests that a compensatory phenomenon occurs in depression. After the patients were treated with antidepressant drugs, an increased affinity (decrease in Kd) was observed, together with a decrease in binding sites. Plasma magnesium concentrations were higher in drug-free depressed patients than in control subjects. In addition, magnesium concentrations were negatively correlated with the density of alpha 2-adrenergic receptor binding sites in depressed patients, both before and during treatment. Lastly, a trend toward a negative correlation between plasma MHPG concentration and the number of binding sites was also observed. These results suggest a complex multifactorial regulation of alpha 2-adrenergic receptors, which are probably hyposensitive in depressive syndromes.

Decrease in epinephrine-induced attenuation of platelet adenylate cyclase activity in depressed patients: relation with plasma electrolytes

We have measured the alpha 2-adrenoceptor-mediated inhibition of platelet membrane adenylate cyclase in depressed patients and control subjects. The results showed a decrease in the forskolin-stimulated adenylate cyclase inhibition of depressed patients compared to the healthy subjects. This suggests a subsensitivity of alpha 2-adrenoceptor in depression. However, this subsensitivity was not correlated to the severity of depression as both severely and moderately depressed patients exhibited the same percent of adenylate cyclase inhibition. The antidepressant drugs treatment induced an increase in the percent of adenylate cyclase inhibition with a trend towards the control values. However, this increase did not equal control value, and moreover both remitted and unremitted patients presented a similar change in their alpha 2-adrenoceptor-mediated adenylate cyclase inhibition. This result raises the question about a simple and direct relation between the clinical status of depression and the power of alpha 2-adrenoceptor-mediated adenylate cyclase inhibition. Plasma magnesium and sodium yielded correlations to this alpha 2-adrenoceptor-mediated adenylate cyclase inhibition suggesting a relation between the platelet adrenergic function and plasma electrolytes.

Evolution of blood magnesium, sodium and potassium in depressed patients followed for three months

No consensus has been obtained about blood electrolyte status, especially about magnesium, in affective disorders. This is mainly due to the lack of information about the distribution of the patients in clinical subgroups, sex, type of treatment and about the severity of their illnesses. Most of these studies concerned treated patients. We confirmed in this study that drug-free depressed patients have higher erythrocyte and plasma magnesium than controls, as shown in previous reports. Significant differences are observed in as shown in previous reports. Significant differences are observed in patients for sex and between clinical subgroups. Low plasma potassium levels are described in both male and female depressed patients. The erythrocyte magnesium level tends to normalize in parallel with clinical improvement, depending on sex and clinical subgroup, and seems then to be related to the intensity of the depression. Plasma magnesium in male and female patients, except for female unipolars, remains higher than controls in all conditions and might be related to the diagnosis of affective disorders.

Effect of specific growth rates on productivity in continuous open and partial cell retention animal cell bioreactors

A clonal derivative of a transfectant of the SP2/0 myeloma cell line producing a chimeric monoclonal antibody was cultivated in both continuous open and continuous partially-closed bioreactors. Using an open system for the determination of kinetic parameters, we showed that the production of this chimeric mAb was growth associated. As such, the volumetric productivity increased linearly with increasing dilution rate up to the maximum dilution rate. Three continuous cultivations employing partial cell retention were conducted. In agreement with mathematical predictions, the product titer and volumetric productivity were independent of the degree of cell retention when the total dilution was held constant. When cells were maintained at a low specific growth rate, the product titer was independent of dilution rate and the volumetric productivity increased with increasing dilution rate, again in agreement with mathematical predictions. Since the partially-closed bioreactor could be operated at dilution rates in excess of the maximum specific cellular growth rate, volumetric productivities were greater than those achievable in the open bioreactor. However, when cells were maintained at a high specific growth rate, cell accumulation was limited and product titers decreased at high dilution rates. Therefore, the volumetric productivity in this latter case did not increase at higher dilution rates.

[Erythrocyte membrane transports of monoamine precursor amino acids in schizophrenia]

We have determined the erythrocyte membrane uptake of the monoamine precursors L-tyrosine (L-TYR) and L-tryptophane (L-TRYP) in 72 patients with schizophrenia: 21 without neuroleptic treatment and not depressed, 15 with neuroleptic treatment and depressed, 33 without neuroleptic treatment, 27 depressed, compared to: 59 control subjects, and 54 depressed patients. We found that the ratio of L-TYR facilitated membrane diffusion to that of L-TRYP is: decreased when the patients are depressed, increased when they are untreated. When untreated patients receive neuroleptics and are depressed, the ratio tends to equal that of depressed patients'. The meaning of these anomalies is analysed, using our up-to-date knowledge of the erythrocytes's role in uptaking and dispatching the human body amino-acids, and of the role of these uptakes in regulating the functional monoamine balance. We postulate that in depressions, Parkinson's disease and schizophrenia, a change of membrane fluidity occurs, being decreased in depressions and Parkinsons's disease, and increased in schizophrenia.

L-tyrosine and L-tryptophan membrane transport in erythrocytes and antidepressant drug choice

In the treatment of depression, when antidepressant drug choice is made according to alterations of erythrocyte membrane transport of L-tyrosine and L-tryptophan in the individual patient, the clinical results are superior to those obtained when drugs are prescribed according to the physician's judgment. This is demonstrated by comparing three experimental groups: I, 100 patients treated in relation to their L-tyrosine and L-tryptophan transport; II, 30 patients treated according to the clinician's experience; III, 38 subjects treated against the L-tyrosine and L-tryptophan transport indications. In these groups, the frequency of patients improved by more than 70% is 77%, 47%, and 16%, respectively.

Reversible in vitro decrease of L-tyrosine and L-tryptophan influx across the human erythrocyte membrane induced by cytochalasin B, the specific inhibitor of D-glucose transport

For many years, we have been studying, in psychiatric conditions, the influx of tyrosine (TYR) and tryptophan (TRP), the two amino acid precursors of monoamines, across the membrane of human blood cells. We have also attempted to characterize better the transport mechanisms. In a previous paper, we suggested a close relationship between glucose and the two neuter amino acid transports in vitro. The purpose of the present study is to test the effect of cytochalasin B, the specific and potent inhibitor of glucose transport. Our data show that at high concentrations, the cytochalasin B induces a reversible inhibition of about 70% or more on the temperature-dependent influx of the two amino acids, depending on the medium of incubation. The effect of cytochalasin B was about 200 times less for TYR and TRP transport than for glucose. The cytochalasin E, claimed to be a nonspecific inhibitor, decreased both these transports only when used at very high concentrations, as described for sugar influx in the same structure. In conclusion, we suggest that there is a relationship between the transport of glucose and nucleosides, both carried into the cells by the glycoprotein band 4.5, and the two amino acid precursors of monoamines.

A multivariate analysis of red blood cell membrane transports and plasma levels of L-tyrosine and L-tryptophan in depressed patients before treatment and after clinical improvement

The purpose of this study was to examine whether biological variables, such as erythrocyte membrane transports and plasma levels of monoamine precursor amino acids (tyrosine, tryptophan and phenylalanine), exhibit a particular pattern relatively to DSM-III depressive subgroups (dysthymic disorders, major recurrent depression and biopolar depression), when they are treated synthetically by a stepwise discriminant analysis. We conducted two tests in 97 subjects (64 depressed patients vs. 33 controls): the first before any antidepressant treatment, and the second after pharmacotherapy and clinical improvement. Our results clearly indicate a satisfying homogeneity for the controls and bipolar depressed patients as opposed to dysthymic disorders and major recurrent depression in both tests. The most informative biological variables are the erythrocyte membrane transports before treatment, tryptophan parameters after clinical improvement. Evidence is provided that multivariate analysis constitutes an interesting approach in biological psychiatry.

Histological and clinical parameters of human gingiva following 3 weeks of chemical (chlorhexidine) or mechanical plaque control

The aim of the present study was to compare stereologically the histopathologic variations following 3 weeks of chemical (chlorhexidine) or mechanical plaque control. 18 students and dental hygienists volunteered for this investigation. After prophylaxis, they performed optimal oral hygiene to reach mean plaque and gingival indices approaching 0. Six of them then performed mechanical plaque control of 3 weeks (control), while the other 12 rinsed 3 times daily with a 0.12% chlorhexidine solution (test). At days 0 and 21, the plaque index (PlI), the gingival index (Gl) and the gingival exudate flow rate (GEFR) were assessed and biopsies were obtained from buccal sites. Point-counting procedures were performed at 2 different levels of magnification on light microscopic sections to estimate the volume fractions of epithelium, infiltrated and non-infiltrated connective tissue, and collagen. The relative numbers of fibroblasts, polymorphonuclear neutrophils, lymphocytes, plasma cells, macrophages and mast cells were estimated by counting the number of nuclear profiles of these cells in a specific connective tissue area adjacent to the apical termination of the junctional epithelium. After 21 days, the PlIs of the test subjects were significantly higher than the PlIs of the controls, but their Gl were similar. At the end of the experimental period, the various volume fractions and %s of cell profiles remained stable with the exception of an increase in the %s of lymphocytes in the test group. This study has shown that, clinically as well as histologically, the daily use of chlorhexidine for a 3-week period is equally efficient as optimal mechanical tooth cleaning in maintaining a healthy gingiva in the buccal sites investigated.

Involvement of sulfhydryl groups in the transport of L-tyrosine and L-tryptophan across the human red cell membrane in vitro

In previous papers, we reported a deficit in tyrosine (TYR) and tryptophan (TRP) transport across the erythrocyte membrane in depressed patients. To investigate further the transport mechanism of the two precursors of monoamines, we tested in healthy subjects the role played by sulfhydryl groups (SH). These groups, cysteine residues, are localized on the intrinsic domain such as the transporters of chloride or sugars. We found that all sulfhydryl reagents that inactivated the SH induced a strong inhibition of the transport of amino acid across the red cell membrane when incubated in the plasma as medium. We concluded that a relationship might exist between these neutral amino acids and D-glucose transport.

[Efficacy of antidepressants selected as a function of erythrocyte membrane transport and plasma levels of L-tyrosine and L-tryptophan]

The present study concerned 69 depressed patients (26 men, 43 women). The antidepressant drug was prescribed in accordance with perturbations of tyrosine and tryptophan membrane transports (MT) across the red cell, measured in vitro after a wash-out period of ten days. After two to four months of treatment, the clinical results were divided into two groups: normal mood (AMDP - Depression Scale less than 6) and no recovery (AMDP - Depression Scale greater than 6). The initial criteria (e.g. MT) was completed by using plasma tyrosine, tryptophan and the product MT by plasma level. Indeed, the success of this treatment was corresponding to precise abnormalities of variable: (i) tyrosine and tryptophan values for imipramine, (ii) tyrosine values, plasma tryptophan and tryptophan product for desipramine, (iii) tryptophan variables and plasma tyrosine for fluvoxamine (and indalpine). The analysis of clinical failures permitted to complete our previous choice of antidepressant drug.

[Erythrocyte membrane transport and plasma levels of tyrosine and tryptophan in depression]

L-Tyrosine and L-Tryptophan were studied in 80 depressed patients, hospitalised in Genova and Marseille. After a washout period of ten days, the erythrocyte membrane transports (MT) of L-Tyrosine and L-Tryptophan were measured, as well as their plasma levels; plasma phenylalanine was moreover measured. 33 normal subjects served as control group. In the whole population of patients, the mean of MT's was different compared to controls (MT tyrosine low and MT tryptophan high) and the plasma tyrosine was low. The perturbations of these variables were different according to diagnostic groups (DSM III): MT tyrosine, plasma tyrosine and tryptophan low in bipolar disorders depressed; MT tyrosine low, MT tryptophan high, plasma tryptophan low in major depressions; MT tryptophan high in dysthymic disorders. Phenylalanine was in the normal range compared to controls. The perturbations of MT's involved the part incubated at 37 degrees C for tyrosine, e.g. the facilitated diffusion, and the part incubated at 0 degrees C for tryptophan, e.g. probably the passive and facilitated diffusion. These results were in agreement with the monoaminergic hypothesis of affective disorders and might provide a useful peripheral model.

[Joint evolution of erythrocyte membrane transport of tyrosine and tryptophan as a function of the clinical course of depression]

The clinical state and the erythrocyte membrane transports of tyrosine and tryptophan were studied longitudinally during one year (minimum period of 3 months) in 44 depressive patients, 21 men and 23 women of 30 to 77 years of age. According to the DSM III, 18 patients had bipolar disorders (8 with short cycles), 14 had recurrent major depressions and 12 dysthymic disorders. Abnormal values for the membrane transports are found in the majority of patients; the pattern of these abnormalities differs among the nosological groups but decreased ratio of the tyrosine to tryptophan is the predominant finding. The membrane transports normalize as the clinical status improves. In bipolar disorders, the changes observed at the time of switching into mania differ among short and long cyclers. Short cyclers who become manic generally present a short period of normal mood and show values of membrane transports higher than when depressed or euthymic and higher than those of normal controls. Long cyclers directly switch into mania, and when manic have the same ratio of tyrosine to tryptophan than when depressed. Based on these biochemical observations, long cyclers resemble patients with recurrent major depression and short cyclers resemble dysthymic disorder patients, a group for which it has been suggested that one fifth become bipolar within years of evolution.

Evolution of red blood cell membrane transport and plasma level of L-tyrosine and L-tryptophan in depressed treated patients according to clinical improvement

The erythrocyte membrane transport (MT) of L-tyrosine (TYR) and L-tryptophan (TRP) and their plasma concentration showed abnormal mean values in 37 depressed patients compared to control subjects before treatment. The pattern of these abnormal values differed according to the clinical subgroup (DSM III criteria). In bipolar disorders the TYR values were all low and the TRP values showed little change, except a low level of plasma TRP. In major depression, MT were abnormal (MT TYR low, MT TRP high) with a very low plasma TRP. In dysthymic disorders the TYR and TRP values were normal. The normalization of the above biochemical variables was significantly correlated with the clinical improvement; however, the plasma concentration of TRP remained abnormal in some patients who had recovered. In contrast, only plasma TYR and TRP were significantly increased in patients without recovery.

Individuality and stability in the transport of precursors of monoamines across the erythrocyte membrane of mentally normal subjects

We evaluated to what extent the tyrosine (TYR) and tryptophan (TRP) transport by the red cells was stable in normal subjects during divers clinical conditions. Twenty-two normal subjects were studied. The values of TYR and TRP transport were found to be individually determined, showed no circadian oscillations and no changes during the menstrual cycle, but varied somewhat more during the postpartum period. A few normal subjects had low TYR and TRP transport values, as observed in patients with affective disorders.

In vitro effects of short-chain aliphatic alcohols, benzyl alcohol and chlorpromazine on the transport of precursors of monoamines across the human erythrocyte membrane

In previous papers we reported a deficit of tyrosine (TYR) and tryptophan (TRP) transport across the erythrocyte membrane in depressed patients. To investigate further the transport mechanism of both monoamine precursors, we tested in healthy subjects the role played by membrane fluidity, using different fluidizing agents such as alcohols and the neuroleptic chlorpromazine. We found that the transport of both amino acids depended on the length of the chain of each alcohol tested (number of carbon atoms = C). No inhibition was observed after methanol (C1) preincubation, in contrast to benzyl alcohol (C6), which produced an inhibition of about 80% of amino acid basal transport. In a condition of incubation by suspension of cells in an artificial medium, we observed a dose response of these transports with ethanol used at doses of 0.1-1.3 M. Finally we found in this study that the effect of ethanol on membrane fluidity, and therefore on inhibition of basal amino acid transport, was totally reversible after having washed the suspended cells, suggesting a superficial, noncovalent ethanol binding on such biological membranes.

[Choice of antidepressive agents as a function of membrane transport (erythrocytes) of monoamine precursors (L-tyrosine and L-tryptophan)]

In a group of 66 depressed patients, the choice of the antidepressant drug was based upon the result of tyrosine and tryptophan uptake by the membrane of red blood cells. After one month of treatment, 56 subjects were improved, that is 85% of the cases. This result is discussed in comparison with the percentage of improvement described in the literature.

[Erythrocyte membrane transport of L-tyrosine and L-tryptophan in 66 patients with depressive syndromes. Preliminary results]

The transport of Tyrosine and Tryptophan by the membrane of red blood cells has been studied in a group of 66 depressed patients (DSM-III: 27 major depressions, single episode or recurrent; 17 bipolar disorders, depressed; 22 dysthymic disorders). Anomalies were observed: tyrosine transport was decreased in the bipolar disorders and in the major depressions; tryptophan transport was increased in the major depressions and in the dysthymic disorders. These results suggest that membrane transports are disturbed in depressed syndromes, and may be related to dysfunction in the monoaminergic balance.

In vitro effects of ionophores and inhibitors of main sodium and calcium movements on tyrosine and tryptophan transport by human erythrocytes

Peripheral models using blood cells might be biochemical markers in various psychiatric illnesses. In previous papers we reported a deficit of tyrosine and tryptophan transport in red cells incubated in plasma from depressed patients. In the present study we investigated the role played by sodium and calcium in these transports by using inhibitors and ionophores of the main movements of these electrolytes. We also studied the contribution of phloretin-sensitive countertransport, which has been described as low in psychiatric conditions.

Influence of the time of administration of dexamethasone 0.25 mg on cortisol secretion in normal humans

Single low doses (0.25 mg) of dexamethasone were given at 11 p.m., 2, 5 and 8 a.m. on separate days to five normal subjects. The concentrations of cortisol in plasma on the next day were significantly decreased compared to results after placebo administration, and cortisol suppression was maximal after dexamethasone had been given at 8 a.m. Our findings suggests that the postulated phase-advance of circadian rhythms is not a major cause of cortisol non-suppression in depressives given dexamethasone.

L-tyrosine and L-tryptophan transport in red blood cells in normal subjects. Effects of other amino acids, temperature and medium of incubation

Blood cells may be used as a model in the central transport mechanisms of amino acids, precursors of amines, implicated in some hypotheses of psychiatric diseases. In a previous paper, we showed a deficit of tyrosine transport by red cells incubated in the plasma of depressed patients. In the present study, we have investigated the interaction of these peripheral transport mechanisms for tyrosine and tryptophan with other amino acid transports, such as the L and ASC systems, and the role of sodium ions in the extracellular medium. We also describe the inhibition induced by incubation at a low temperature, and a probable role of the membrane viscosity. The interest of incubating the cells in their own plasma, in order to have physiological conditions, is also discussed.