The influence of psychological stress on total serum protein and patterns obtained in serum protein electrophoresis

BACKGROUND

Significant alterations in total serum protein (TSP) patterns obtained in serum protein electrophoresis and serum proteins have been reported in patients with major depression and in subjects submitted to a combination of psychological and physical stress. The aim of the present study was to examine the effects of academic examination stress, on TSP and patterns obtained in serum protein electrophoresis.

METHODS

TSP and the concentrations and percentages of the major electrophoretically separated serum proteins were measured in 41 healthy biomedical students the day before a difficult academic examination (i.e. the stressful condition), as well as a few weeks before and after the stressful condition (i.e. two baseline conditions).

RESULTS

Academic examination stress increased TSP and the alpha 1, alpha 2, beta and gamma concentrations in stress-reactors, but not in stress non-reactors (as defined by changes in the Perceived Stress Scale). Academic examination stress reduced the percentage of albumin in the stress-reactors, but not in stress non-reactors. There were significant positive relationships between the stress-induced changes in TSP and serum alpha 2, beta and gamma concentrations and the stress-induced changes in the Perceived Stress Scale.

CONCLUSIONS

The results show that even mild psychological stress of short duration can lead to measurable changes in TSP and in patterns obtained in serum protein electrophoresis.

Increased serum IL-6 and IL-1 receptor antagonist concentrations in major depression and treatment resistant depression

There is now some evidence that major depression is accompanied by an immune response with an increased production of pro-inflammatory cytokines, such as interleukin 1(IL-1), IL-6 and interferon gamma (IFN-gamma). The aims of the present study were to examine serum IL-6, IL-1 receptor antagonist (IL-1Ra), IL-6R, Clara cell protein (CC16) and the soluble CD8 (sCD8) molecule in chronic, treatment resistant depression (TRD) both before and after subchronic treatment with antidepressants. Serum IL-6 and IL-1Ra were significantly higher in subjects with major depression and TRD than in normal controls. Subchronic treatment with antidepressants had no significant effects on serum IL-6, IL-1Ra, CC16 or sCD8, but reduced serum sIL-6R levels significantly. There were significant and positive correlations between serum IL-6, on the one hand, and sIL-6R, IL-1Ra, sCD8, number of peripheral blood leukocytes, neutrophils, CD2(+)T and CD19(+)B cells (all positive) and serum zinc (negative), on the other. These results suggest that: (1) major depression and TRD are accompanied by an activation of the monocytic arm of cell-mediated immunity; (2) the latter may be related to the immune an acute phase response in major depression; and (3) the above disorders may persist despite successful antidepressive treatment.

Effects of trazodone and fluoxetine in the treatment of major depression: therapeutic pharmacokinetic and pharmacodynamic interactions through formation of meta-chlorophenylpiperazine

It has been suggested that (1) the clinical efficacy of the heterocyclic antidepressant trazodone in depression may, in part, be attributed to its metabolite meta-chlorophenylpiperazine (mCPP); and (2) the enhancement of the efficacy of trazodone by the addition of fluoxetine, a selective serotonin reuptake inhibitor, may, in part, be ascribed to fluoxetine-induced plasma concentrations of trazodone. After a washout period of 10 days, 27 inpatients with major depression were treated with trazodone 100 mg/day (orally). One week later (T0), fluoxetine 20 mg/day, placebo, or pindolol 7.5 mg/day was added. Plasma concentrations of mCPP and trazodone were determined at T0 and 2 and 4 weeks later. Although placebo pindolol had no significant effect on the plasma concentrations of mCPP and trazodone, there was a significant increase of the concentrations of these compounds associated with the combination of trazodone + fluoxetine. The results suggest that fluoxetine-induced increases in plasma mCPP and trazodone concentrations contribute to the clinical efficacy of the combination of fluoxetine + trazodone. It is suggested that desensitization of 5-HT2C receptor function by mCPP as well as fluoxetine may contribute to the antidepressant effects of this combination.

Lower serum zinc in major depression is a sensitive marker of treatment resistance and of the immune/inflammatory response in that illness

The aims of the present study were to examine i) serum zinc (Zn) and copper (Cu) in treatment resistant depression (TRD); ii) the effects of subchronic antidepressant therapy on these trace elements; and iii) the relationships between serum Zn and Cu and immune/inflammatory markers. Serum Zn was significantly lower in TRD than in normal controls. There was a significant inverse correlation between baseline serum Zn and staging of depression based on severity of prior treatment resistance. There were no significant effects of antidepressive treatment on serum Zn, whereas serum Cu was significantly reduced. There were highly significant correlations between serum Zn and the CD4+/CD8+ T-cell ratio (negative), and total serum protein, serum albumin, and transferrin (all positive). The results suggest that lower serum Zn is a marker of TRD and of the immune/inflammatory response in depression. It is suggested that treatment resistance may bear a relationship with the immune/inflammatory alterations in major depression.

Serum creatine, creatinine, and other guanidino compounds in patients with thyroid dysfunction

Serum levels of creatine (CT), creatinine (CTN), urea, guanidinosuccinic acid (GSA), guanidinoacetic acid (GAA), guanidine (G), arginine (Arg), homoarginine (Harg), argininic acid (ArgA), and alpha-keto-delta-guanidinovaleric acid (alpha-K-delta-GVA) were measured in 54 patients with hyperthyroidism, 56 with subclinical hyperthyroidism, 28 with subclinical hypothyroidism, and 51 with hypothyroidism compared with 62 euthyroid controls. In agreement with previous reports, serum CT increased (+35%) and CTN decreased (-17.6%) in hyperthyroidism as compared with normal thyroid function, whereas the opposite was seen in hypothyroidism (-17.7% and +11%, P < .0001). Original findings from this study are a highly significant decrease in GSA (-41.7%) and GAA (-36.8%) in hyperthyroidism and an increase in GSA (+36%) in hypothyroidism (P < .0001). In addition, a slight decrease in hyperthyroidism and hypothyroidism was noted for Arg (-6.2% and -13.2%, P = .001) and Harg (-14.8% and -18.1%, P = .05). By contrast, no significant change was seen in levels of urea, G, ArgA, and alpha-K-delta-GVA. No major differences were found for any of the compounds between subclinical hypothyroidism, euthyroidism, and subclinical hyperthyroidism. There was a highly significant positive linear correlation between urea and GSA levels in hyperthyroidism, euthyroidism, and hypothyroidism (r = .68, r = .77, and r = .75, P < .0001), taking into account that for the same increase in urea, GSA increased threefold more in hypothyroid versus hyperthyroid patients. In conclusion, apart from CT and CTN, significant changes can be found in serum levels of GSA, GAA, Arg, and Harg in patients with thyroid dysfunction. Subclinical thyroid dysfunction does not seem to induce changes in serum levels of guanidino compounds. Decreased serum GSA and GAA levels might be an additional indicator of hyperthyroidism.

Analysis of the antiepileptic phenyltriazine compound lamotrigine using gas chromatography with nitrogen phosphorus detection

A method is described for the determination of lamotrigine in serum or plasma, based on gas chromatography with nitrogen-phosphorus detection. The method requires minimal sample preparation. The drug is extracted from 1.0 ml of serum at pH 11 into butylacetate containing prazepam as internal standard. An aliquot of the organic phase is then injected onto an HP-5 fused silica capillary column and analyzed with temperature programming from 90 degrees to 250 degrees C. Lamotrigine is characterized by a relative retention time of 0.832 (+/-0.03) compared with prazepam. The method is competitive with the reported high-performance liquid chromatography procedures in terms of precision and sensitivity. Coefficients of variation, calculated from the results of between-run reproducibility tests, were 6.7%, 4.6%, 4.8%, and 6.2% for samples spiked with 0.20, 1.21, 2.42 and 10.84 micrograms/ml lamotrigine, respectively. The lower limit of quantitation of the method is 0.15 microgram/ml. The proposed procedure can be integrated easily in a comprehensive toxicology screening.

Effects of psychological stress on serum immunoglobulin, complement and acute phase protein concentrations in normal volunteers

The aim of this study was to examine the effects of academic examination stress on serum immunoglobulins (Igs), i.e. IgA, IgG, IgM, complement factors, i.e. C3c and C4, and acute phase proteins, i.e. alpha 1-acid glycoprotein (alpha 1-S), haptoglobin (Hp) and alpha 2-macroglobulin (alpha 2-M). Thirty-seven university students participated in this study. Serum was sampled a few weeks before and after as well as one day before a difficult academic examination. On the same occasions, students completed the Perceived Stress Scale (PSS). Students were divided into two groups, i.e. those with high- and low-stress perception as defined by changes in the PSS score. Academic examination stress induced significant increases in serum IgA, IgG, IgM, and alpha 2-M in students with high-stress perception, but not in these with low-stress perception. The stress-induced changes in serum IgA, C3c, and alpha 1-S concentrations were significantly higher in students with high-stress perception than in those with a low-stress perception. The stress-induced changes in serum IgA, IgM, C3c, C4, alpha 1-S, Hp and alpha 2-M were normalized a few weeks after the stress condition, whereas IgG showed a trend toward normalization. There were significant positive relationships between the stress-induced changes in the PSS and serum IgA, IgG, IgM and alpha 2-M. These findings suggest that psychological stress is accompanied by an altered secretion of serum Igs, complement factors and some acute phase proteins.

Haptoglobin polymorphism, a genetic risk factor in coronary artery bypass surgery

Haptoglobin (Hp) 2-2 type has been associated with accumulation of atherosclerotic lesions in essential hypertension. The aim of this study was to investigate the relationship between Hp type and the extension of coronary lesions in 765 male patients who underwent coronary artery bypass grafting (CABG). In this group, relative Hp1 (0.418) and Hp2 (0.582) allele frequencies were comparable with those of the reference population. Candidate CABG patients with a Hp 2-2 type were overrepresented in the younger (< 45 years) age group (P < 0.05). Hp 2-2 patients needed more bypass grafts than Hp 1-1 patients (relative risk 1.92 95% C.I. 1.24-2.96). The Hp 2-2 type was overrepresented among victims of a previous acute myocardial infarction (P < 0.05) and among patients with a lower (< 45 years) age at infarction (P < 0.05). In patients who already underwent a previous CABG graft survival time was shortest in Hp 2-2 type (P < 0.05). Patients with a Hp 2-2 type more likely develop atherosclerotic lesions despite comparable serum lipid concentrations.

Hypothalamic-pituitary-thyroid-axis function in treatment resistant depression

Recently, there were some reports that the prevalence of various grades of hypothyroidism may be increased in patients with treatment resistant depression (TRD). The aim of the present study was to examine serum basal thyroid-stimulating hormone (TSH) and thyroxine (T4) levels in 36 major depressed subjects, of whom 27 had TRD and 15 were normal volunteers. There were no significant differences in serum basal TSH or T4 levels between major depressed subjects and normal controls, or between patients with TRD versus normal controls or subjects without TRD. There was a trend towards lower serum basal T4 concentrations in patients with TRD than in other depressed patients and normal controls. One patient with TRD had basal serum TSH levels in the hyperthyroid range. Two subjects, one with TRD and one normal control, had serum TSH values in the subclinical hypothyroid zone, but their serum T4 values were in the euthyroid range. There were no significant relationships between basal TSH or T4 and severity of illness, staging of depression based on prior treatment non-response, length of the depressive episode, duration of illness, or number of previous depressive episodes. In conclusion, the results of this study do not provide evidence that (subclinical) hypothyroidism occurs more than coincidentally in depressed patients with TRD.

Lower serum high-density lipoprotein cholesterol (HDL-C) in major depression and in depressed men with serious suicidal attempts: relationship with immune-inflammatory markers

Recently, there have been some reports that changes in serum lipid composition may be related to suicide, major depression and immune-inflammatory responses. Findings from our laboratory suggest that major depression is accompanied by reduced formation of cholesteryl esters and perhaps by impairment of reverse cholesterol transport. The latter is reportedly accompanied by lower serum high-density lipoprotein cholesterol (HDL-C). The aim of this study was to examine whether (i) major depression is accompanied by lower serum HDL-C or by abnormal levels of serum total cholesterol, triglycerides, low-density lipoprotein-C (LDL-C) or vitamin E, (ii) suicidal attempts are related to lower serum HDL-C and (iii) there are significant associations between serum HDL-C and immune/inflammatory markers. A total of 36 subjects with major depression, of whom 28 patients showed treatment resistance, as well as 28 normal control subjects, had blood sampled for the assay of the above lipids, serum zinc (Zn), albumin (Alb) and flow cytometric determination of the T-helper/T-suppressor (CD4+/CD8+) T-cell ratio. In total, 28 depressed subjects had repeated measures of these variables both before and after treatment with antidepressants. Serum HDL-C and total cholesterol, as well as the HDL-C/cholesterol ratio, were significantly lower in subjects with major depression than in normal controls. Serum HDL-C levels were significantly lower in depressed men who had at some time made serious suicidal attempts than in those without such suicidal behaviour. Treatment with antidepressants for 5 weeks did not significantly alter either serum HDL-C or other lipid variables. Serum HDL-C levels were significantly and negatively correlated with the (CD4+/CD8+) T-cell ratio, and positively correlated with serum Alb and Zn. These results suggest that (i) lower serum HDL-C levels are a marker for major depression and suicidal behaviour in depressed men, (ii) lower serum HDL-C levels are probably induced by the immune/inflammatory response in depression and (iii) there is impairment of reverse cholesterol transport from the body tissues to the liver.

Lower serum dipeptidyl peptidase IV activity in treatment resistant major depression: relationships with immune-inflammatory markers

Previous research in this laboratory has shown that major depression is accompanied by decreased serum activity of dipeptidyl peptidase IV (DPP IV), a serine protease that cleaves N terminal dipeptides from peptides with penultimate proline or alanine. DPP IV is involved in the metabolism of peptides, T cell activation and proliferation, including the production of cytokines, such as interleukin-1 (IL-1) and IL-2. The aim of this study was to examine (i) serum DPP IV activity in major and treatment resistant depression (TRD) in relation to other established immune and inflammatory markers of that illness, and (ii) the effects of antidepressive treatment on DPP IV activity. Serum DPP IV activity was significantly lower in major depression and TRD than in normal controls. In normal and major depressed subjects, there were significant and positive relationships between serum DPP IV activity and total serum protein, serum albumin, zinc, iron and transferrin. In the group of depressed subjects, there were significant and positive relationships between serum DPP IV activity and number of CD4+T cells and CD4+/CD8+ T cell ratio. There were no significant effects of subchronic treatment with antidepressants on serum DPP IV activity. The findings suggest that: (i) lower serum DPP activity may occur in chronic depression, TRD as well as in the acute phase of major depression; (ii) lower serum DPP IV accompanies the 'chronic' acute phase response in depression; and (iii) serum DPP IV activity is tightly coupled to increased number of CD4+ T cells in depressed subjects, but not in normal controls. Our results do not exclude the possible effects of longer-term treatment with antidepressants on serum DPP-IV activity.

Components of biological variation in serum soluble transferrin receptor: relationships to serum iron, transferrin and ferritin concentrations, and immune and haematological variables

We investigated the components of biological variation in serum soluble transferrin receptor (TfR) in relation to serum iron, transferrin (Tf), ferritin, soluble interleukin-2 receptor (sIL-2R), sIL-6R, and number of erythrocytes, haemoglobin (Hb), haematocrit (Ht), mean corpuscular volume (MCV), mean cell haemoglobin (MCH), and erythrocyte distribution width (RDW). We took monthly blood samples during 1 calendar year from 26 healthy subjects for assay of the above variables. The estimated CVs for TfR were interindividual CVg = 20.8%, and intra-individual CVi = 13.6%; for Tf, CVg = 14.4% and CVi = 6.7%; for iron, CVg = 16.8% and CVi = 29.2%; and for ferritin, CVg = 71.1% and CVi = 26.5%. There was a statistically significant seasonal pattern in the four variables with significant annual, biannual and/or trimonthly rhythms, which were expressed as a group phenomenon. The peak-trough differences in the yearly variations, expressed as a percentage of the mean, were: for TfR, 11.7%; for iron, 39.2%; for Tf, 11.7%; and for ferritin, 29.3%. Up to 34.2% of the within-subject variability in TfR (which reflects changes over time) could be explained by the regression on iron, ferritin, Tf, sIL-2R, sIL-6R and MCH values. Up to 67.2% of the between-subject variability in TfR (which reflects differences in the homeostatic setpoint during the study year) could be explained by the regression on gender, iron, Tf, and ferritin values.

Erythropoietin response is blunted in critically ill patients

OBJECTIVES

Critically ill patients often develop anaemia which can be related to a number of factors. However, the exact causes of anaemia in many patients remain unexplained. We hypothesized that the relationship between erythropoietin (EPO) and haematocrit may be altered in critically ill patients.

DESIGN

Serum concentrations of EPO were serially determined by the ELISA method in 36 critically ill, non-hypoxaemic patients who stayed more than 7 days in the Intensive Care Unit, including 22 patients with sepsis and 14 without. Eighteen ambulatory patients with iron-deficiency anaemia served as a control group.

SETTING

Two University Hospital Intensive Care Departments.

RESULTS

A significant inverse correlation between serum EPO and haematocrit levels was found in the control patients (r = -0.81, p < 0.001), but not in the critically ill patients (r = -0.09, NS), except in a subgroup of non-septic patients without renal failure (r = -0.61, p < 0.01).

CONCLUSIONS

EPO levels can be inappropriately low in critically ill patients, so that EPO deficiency may contribute to the development of anaemia in these patients. This phenomenon is observed not only in the presence of acute renal failure, but also in the presence of sepsis.

Serotonin-immune interactions in major depression: lower serum tryptophan as a marker of an immune-inflammatory response

Serum total tryptophan and the five competing amino acids (CAA), i.e., valine, leucine, tyrosine, phenylalanine, and isoleucine were determined in 35 major depressed subjects of whom 27 with treatment resistant depression (TRD), and 15 normal controls. Twenty-five of the depressed subjects had repeated measurements of the amino acids both before and after antidepressive treatment. The following immune-inflammatory variables were assayed in the above subjects: serum zinc (Zn), total serum protein (TSP), albumin (Alb), transferrin (Tf), iron (Fe), high-density lipoprotein cholesterol (HDL-C), number of peripheral blood leukocytes, and the CD4+/CD8+ T cell (T-helper/T-suppressor) ratio. Serum tryptophan and the tryptophan/CAA ratio were significantly lower in major depressed subjects than in normal controls. The tryptophan/CAA ratio was significantly lower in patients with TRD than in patients without TRD and normal controls. There were no significant alterations in any of the amino acids upon successful therapy. There were significant correlations between serum tryptophan and serum Zn, TSP, Alb, Tf, Fe, and HDL-C (all positive), and number of leukocytes and the CD4+/CD8+ T-cell ratio (all negative). The tryptophan/CAA ratio was significantly and negatively related to the number of leukocytes and the CD4+/CD8+ T-cell ratio. The results suggest that (a) TRD is characterized by lower availability of serum tryptophan; (b) the availability of tryptophan may remain decreased despite clinical recovery; and (c) the lower availability of tryptophan is probably a marker of the immune-inflammatory response during major depression.

Lower total serum protein, albumin, and beta- and gamma-globulin in major and treatment-resistant depression: effects of antidepressant treatments

Strong evidence has recently been reported that major depression is accompanied by an acute phase response (APR), characterized by elevated levels of positive acute phase proteins (APPs) and decreased levels of negative APPs. The APR is also reflected in lowered total serum protein (TSP) and specific changes in the major electrophoretically separated protein fractions. The present study examined pretreatment and posttreatment serum TSP and the concentrations and percentages of the major electrophoretically separated serum protein fractions in 37 major depressed subjects, of whom 29 had treatment-resistant depression (TRD), and in 29 normal controls. We found that TSP and the percentage and concentration of serum albumin (Alb) and gamma-globulin fraction were significantly lower in major depression and TRD than in normal controls. Serum beta-globulin concentrations were significantly lower in major depressed and TRD subjects than in normal controls. The percentages of the alpha 1- and alpha 2-globulin fractions were significantly higher in major depressed subjects than in normal controls. There were no significant effects of subchronic treatment with antidepressants on TSP, the percentage or concentration of the major electrophoretically separated protein fractions, i.e. alpha 1-, alpha 2- and beta-globulin. There was a significant increase in percentage of the gamma-globulin fraction after subchronic treatment with antidepressants. The results support the hypothesis that major depression and TRD are accompanied by a chronic APR.

Biological variability in serum vitamin E concentrations: relation to serum lipids

The components of biological variation in serum vitamin E in relation to serum cholesterol, triglycerides, high- and low-density lipoprotein cholesterol (HDL-C, LDL-C), apolipoprotein A-I (apo A-I), and apo B were examined in 26 healthy volunteers who had monthly blood samplings during one calendar year. The estimated CVs for vitamin E were: interindividual, 19.9%, and intraindividual, 11.9%; the index of individuality (I-index) was 0.59. The I-indices for all lipid variables were &lt; 0.51. Serum concentrations of vitamin E, cholesterol, triglycerides, HDL-C, LDL-C, and apo B were lower in spring than in the other seasons. The peak-trough differences in the yearly variations, expressed as a percentage of the mean, were for vitamin E 14.5%, cholesterol 16.2%, triglycerides 14.5%, and LDL-C 24.3%. A significant common annual rhythm was expressed in vitamin E or lipid variables and in the changes in ambient temperature the weeks before blood sampling (inverse relations). There were highly significant positive time relations between serum vitamin E and cholesterol, triglycerides, and apo B. Subjects with higher homeostatic setpoints of cholesterol showed higher homeostatic setpoints of vitamin E, triglycerides, LDL-C, and apo B.

Biological variability in serum vitamin E concentrations: relation to serum lipids

The components of biological variation in serum vitamin E in relation to serum cholesterol, triglycerides, high- and low-density lipoprotein cholesterol (HDL-C, LDL-C), apolipoprotein A-I (apo A-I), and apo B were examined in 26 healthy volunteers who had monthly blood samplings during one calendar year. The estimated CVs for vitamin E were: interindividual, 19.9%, and intraindividual, 11.9%; the index of individuality (I-index) was 0.59. The I-indices for all lipid variables were < 0.51. Serum concentrations of vitamin E, cholesterol, triglycerides, HDL-C, LDL-C, and apo B were lower in spring than in the other seasons. The peak-trough differences in the yearly variations, expressed as a percentage of the mean, were for vitamin E 14.5%, cholesterol 16.2%, triglycerides 14.5%, and LDL-C 24.3%. A significant common annual rhythm was expressed in vitamin E or lipid variables and in the changes in ambient temperature the weeks before blood sampling (inverse relations). There were highly significant positive time relations between serum vitamin E and cholesterol, triglycerides, and apo B. Subjects with higher homeostatic setpoints of cholesterol showed higher homeostatic setpoints of vitamin E, triglycerides, LDL-C, and apo B.

Alterations in iron metabolism and the erythron in major depression: further evidence for a chronic inflammatory process

There is now some evidence that major depression is accompanied by biochemical and immune changes pointing to the presence of a chronic inflammatory response. The latter condition is reportedly characterized by changes in iron (Fe) metabolism and the erythron, such as decreased serum Fe and transferrin (Tf) and increased serum ferritin, lower number of red blood cells (RBC), lower hematocrit (Htc) and hemoglobin (Hb). The aim of the present study was to examine Fe metabolism and the erythron in 38 major depressed subjects versus 15 normal volunteers, as well as the effects of antidepressant treatments on these variables. Major depressed subjects had significantly lower serum Fe and Tf, a lower number of RBC, lower Htc and Hb, and a significantly increased number of reticulocytes than normal controls. Serum ferritin was significantly higher in major depressed patients with melancholia than in those with simple major depression and normal controls. Mean corpuscular volume (MCV), MC Hb (MCH), MC Hb concentration (MCHC) and RBC distribution width (RDW) were not significantly different between major depressed subjects and normal controls. Treatment with antidepressants during 5 weeks had no significant effect on the alterations in number of RBC and reticulocytes, Htc, Hb, Fe and Tf. There were significant relationships between the above Fe and erythron variables and established immune-inflammatory markers of major depression, e.g., lowered serum albumin and zinc and the increased electrophoretically-separated alpha 1-globulin fraction. The results suggest that the disorders in Fe metabolism and the erythron during major depression may be induced by the immune-inflammatory response in that illness.

Lower serum L-tryptophan availability in depression as a marker of a more generalized disorder in protein metabolism

Recently, it has been reported that major and melancholic depression are accompanied by a lower availability of total L-tryptophan (L-TRP) to the brain and by significant changes in electrophoretically separated protein fractions, such as albumin and alpha 2-globulin. The aim of this study was to examine the relationships between serum L-TRP availability and total serum protein, albumin, and alpha 2-globulin in 42 depressed and 24 normal subjects. In depressed and normal subjects, alone and together, there were significant and positive correlations between serum L-TRP and total serum protein or albumin concentrations. In the depressed subjects, but not in normal controls, there were significant inverse relationships between the L-TRP/competing amino acid ratio and the alpha 2-globulin fraction. Serum L-TRP and albumin were significantly lower in melancholic subjects than in normal and minor depressed subjects. Depressed subjects had a significantly lower L-TRP/competing amino acid ratio and significantly higher serum alpha 2-globulin than normal controls. Total serum protein was significantly lower in major depressed subjects than in normal controls. The results suggest that lower L-TRP availability to the brain in depression is related to lower serum albumin and to increased alpha 2-globulin fraction, which are both hallmarks of the acute phase response in depression. the results further corroborate the hypothesis that lowered L-TRP availability in depression is related to the acute phase response in that illness.

Seasonal variation in plasma L-tryptophan availability in healthy volunteers. Relationships to violent suicide occurrence

OBJECTIVE

To investigate the seasonal variation in levels of plasma L-tryptophan and competing amino acids (CAAs) in healthy humans in relation to climatic variables, total serum protein levels, and violent suicide occurrence.

METHODS

Twenty-six healthy volunteers (13 men and 13 women; mean [+/- SD] age, 38.7 +/- 13.4 years) had monthly blood samplings for assays of L-tryptophan, valine, leucine, isoleucine, tyrosine, and phenylalanine during 1 calendar year.

RESULTS

Significant annual rhythms were detected in L-tryptophan, the L-tryptophan/CAA ratio, phenylalanine, valine, and leucine, and semiannual rhythms in L-tryptophan values and in L-tryptophan/CAA ratios. Plasma L-tryptophan and the L-tryptophan/CAA ratio were significantly lower in the spring than in the other seasons. The peak-trough differences in the yearly variation expressed as a percentage of the mean were 17.1% and 16.1% for L-tryptophan values and L-tryptophan/CAA ratios, respectively. The amplitude of the yearly variation in all CAAs was low, ie, less than 7%. An important part of the variance in L-tryptophan availability (ie, 12% to 14%) could be explained by the composite effects of present and past climatic factors; higher ambient temperature and relative humidity in the face of lower air pressure are the most important predictors of low L-tryptophan availability. Important and positive time relationships were noted between total serum protein level and all amino acid concentrations, and a significant time relationship was also noted between the seasonal variation in L-tryptophan availability and the occurrence of violent suicide in Belgium.

CONCLUSION

Our results show a bimodal seasonal pattern in the availability of plasma L-tryptophan that matches seasonal patterns in the prevalence of violent suicide in the local population and depression in other studies.

Components of biological variation in plasma haptoglobin: relationships to plasma fibrinogen and immune variables, including interleukin-6 and its receptor

We investigated the components of biological variation, including seasonality, in plasma haptoglobin (Hp) levels and the relationships between plasma Hp and interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6), sIL-2R, fibrinogen (Fb) and absolute number of peripheral blood mononuclear cells, such as leukocytes, neutrophils, monocytes, lymphocytes, CD4+, CD8+, CD25+ T cells and CD20+ B cells. Monthly blood samples were taken from 26 normal volunteers during one calendar year. The estimated inter- and intra-individual C.V. values for plasma Hp were 27.9% and 20.0%, respectively; the index of individuality was 0.72. No significant seasonal rhythms could be detected in plasma Hp levels. The yearly mean values in plasma Hp were significantly and positively related to those in plasma Fb, absolute number of leukocytes, neutrophils, CD4+ T cells and the CD4+/CD8+ T cell ratio. 49.0% of the variance in the yearly mean values of plasma Hp could be explained by variances in serum IL-6 and number of CD4+ (positively related) and CD8+ (negatively related) T cells. There were significant and positive time relationships between plasma Hp, on the one hand, and plasma Fb, sIL-6R, sIL-2R and number of leukocytes, neutrophils and monocytes, on the other. A smaller part of the within-subject variability in plasma Hp (i.e. 6.0%) could be explained by serum sIL-6R and sIL-2R. It is concluded that there are (1) important between-subject differences in the homeostatic setpoints of plasma Hp, which are related to those in plasma Fb and in immune status and (2) significant within-subject, time relationships between plasma Hp and indicators of immune activation and plasma Fb.