Plasma levels of 7-hydroxylated dehydroepiandrosterone (DHEA) metabolites and selected amino-thiols as discriminatory tools of Alzheimer's disease and vascular dementia

Altered central and blood glutathione in Alzheimer's disease and mild cognitive impairment: a meta-analysis

BACKGROUND

Increasing evidence implicates oxidative stress (OS) in Alzheimer disease (AD) and mild cognitive impairment (MCI). Depletion of the brain antioxidant glutathione (GSH) may be important in OS-mediated neurodegeneration, though studies of post-mortem brain GSH changes in AD have been inconclusive. Recent in vivo measurements of the brain and blood GSH may shed light on GSH changes earlier in the disease.

AIM

To quantitatively review in vivo GSH in AD and MCI compared to healthy controls (HC) using meta-analyses.

METHOD

Studies with in vivo brain or blood GSH levels in MCI or AD with a HC group were identified using MEDLINE, PsychInfo, and Embase (1947-June 2020). Standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated for outcomes using random effects models. Outcome measures included brain GSH (Meshcher-Garwood Point Resolved Spectroscopy (MEGA-PRESS) versus non-MEGA-PRESS) and blood GSH (intracellular versus extracellular) in AD and MCI. The Q statistic and Egger's test were used to assess heterogeneity and risk of publication bias, respectively.

RESULTS

For brain GSH, 4 AD (AD=135, HC=223) and 4 MCI (MCI=213, HC=211) studies were included. For blood GSH, 26 AD (AD=1203, HC=1135) and 7 MCI (MCI=434, HC=408) studies were included. Brain GSH overall did not differ in AD or MCI compared to HC; however, the subgroup of studies using MEGA-PRESS reported lower brain GSH in AD (SMD [95%CI] -1.45 [-1.83, -1.06], p<0.001) and MCI (-1.15 [-1.71, -0.59], z=4.0, p<0.001). AD had lower intracellular and extracellular blood GSH overall (-0.87 [-1. 30, -0.44], z=3.96, p<0.001). In a subgroup analysis, intracellular GSH was lower in MCI (-0.66 [-1.11, -0.21], p=0.025). Heterogeneity was observed throughout (I² >85%) and not fully accounted by subgroup analysis. Egger's test indicated risk of publication bias.

CONCLUSION

Blood intracellular GSH decrease is seen in MCI, while both intra- and extracellular decreases were seen in AD. Brain GSH is decreased in AD and MCI in subgroup analysis. Potential bias and heterogeneity suggest the need for measurement standardization and additional studies to explore sources of heterogeneity.

Plasma GSH levels and Alzheimer's disease. A prospective approach.: Results from the HELIAD study

BACKGROUND

Potential links between oxidative stress and the pathophysiology of Alzheimer's disease (AD) have been reported in the existing literature. Biological markers of oxidative stress, such as the reduced form of glutathione (GSH), may have a potential role as predictive biomarkers for AD development. The aim of the present study was to explore the longitudinal associations between plasma GSH and the risk of developing AD or cognitive decline, in a sample of community-dwelling, non-demented older adults.

METHODS

Participants from the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD) were included in the present prospective study. The sample used in the analyses consisted of 391 non-demented individuals over the age of 64 (mean age = 73.85 years; SD = 5.06), with available baseline GSH measurements and longitudinal follow-up. Plasma GSH was treated both as a continuous variable and as tertiles in our analyses. Cox proportional hazards models were used to evaluate the hazard ratio (HR) for AD incidence as a function of baseline plasma GSH. Generalized estimating equations (GEE) models were deployed to explore the associations between baseline plasma GSH and the rate of change of performance scores on individual cognitive domains over time. Models were adjusted for age, years of education and sex. Supplementary exploratory models were also adjusted for mild cognitive impairment (MCI) at baseline, risk for malnutrition, physical activity and adherence to the Mediterranean dietary pattern.

RESULTS

A total of 24 incident AD cases occurred during a mean (SD) of 2.99 (0.92) years of follow-up. Individuals in the highest GSH tertile group (highest baseline plasma GSH values) had a 70.1% lower risk for development of AD, compared to those in the lowest one [HR = 0.299 (0.093-0.959); p = 0.042], and also demonstrated a slower rate of decline of their executive functioning over time (5.2% of a standard deviation less decline in the executive composite score for each additional year of follow-up; p = 0.028). The test for trend was also significant suggesting a potential dose-response relationship.

CONCLUSION

In the present study, higher baseline plasma GSH levels were associated with a decreased risk of developing AD and with a better preservation of executive functioning longitudinally.

Ambulatory Neuroproprioceptive Facilitation and Inhibition Physical Therapy Improves Clinical Outcomes in Multiple Sclerosis and Modulates Serum Level of Neuroactive Steroids: A Two-Arm Parallel-Group Exploratory Trial

Background: Only few studies have monitored the potential of physical activity training and physical therapy to modulate the reaction of the endocrine system. In this study, the effect of neuroproprioceptive facilitation and inhibition physical therapy on clinical outcomes and neuroactive steroids production in people with multiple sclerosis was evaluated. Moreover, we were interested in the factors that influence the treatment effect. Methods: In total, 44 patients with multiple sclerosis were randomly divided into two groups. Each group underwent a different kind of two months ambulatory therapy (Motor program activating therapy and Vojta’s reflex locomotion). During the following two months, participants were asked to continue the autotherapy. Primary (serum level of cortisol, cortisone, 7α-OH-DHEA, 7β-OH-DHEA, 7-oxo-DHEA, DHEA) and secondary (balance, cognition and patient-reported outcomes) outcomes were examined three times (pre, post, and washout assessments). Results: In both groups, there is a decreasing trend of 7-oxo-DHEA concentration in post-assessment and 7β-OH-DHEA in washout versus pre-assessment. A higher impact on neuroactive steroids is visible after Vojta’s reflex locomotion. As for clinical outcomes, the Paced Auditory Serial Addition Test and Multiple Sclerosis Impact Scale significantly improved between post-assessment and washout assessment. The improvement was similar for both treatments. Conclusions: Neuroproprioceptive facilitation and inhibition improved the clinical outcomes and led to non-significant changes in neuroactive steroids. Trial registration (NCT04379193).

Neurosteroid pregnenolone sulfate, alone, and as augmentation of lurasidone or tandospirone, rescues phencyclidine-induced deficits in cognitive function and social interaction

BACKGROUND

Pregnenolone sulfate (PregS), an endogenous neurosteroid, which negatively and positively modulates gamma amino butyric acid subunit A (GABA_A) and N-methyl D-aspartate (NMDA) receptors (R) respectively, among other potential neuroplastic changes on synaptic processes, has shown some beneficial effects on treating cognitive impairment associated with schizophrenia (CIAS) and negative symptoms. Lurasidone (Lur), an atypical antipsychotic drug (AAPD), and tandospirone (Tan), a 5-HT_1A R partial agonist, have also been reported to improve cognitive or negative symptoms, or both, in some schizophrenia patients.

METHODS

We tested whether PregS, by itself, and in combination with Lur or Tan could rescue persistent deficits produced by subchronic treatment with the NMDAR antagonist, phencyclidine (PCP)-in episodic memory, executive functioning, and social behavior, using novel object recognition (NOR), operant reversal learning (ORL), and social interaction (SI) tasks, in male C57BL/6 J mice.

RESULTS

PregS (10, but not 3 mg/kg) significantly rescued subchronic PCP-induced NOR and SI deficits. Co-administration of sub-effective doses (SEDs) of PregS (3 mg/kg) + Lur (0.1 mg/kg) or Tan (0.03 mg/kg) rescued scPCP-induced NOR and SI deficits. Further, PregS (30, but not 10 mg/kg) rescued PCP-induced ORL deficit, as did the combination of SED PregS (10 mg/kg) +SED Lur (1 mg/kg) or Tan (1 mg/kg).

CONCLUSION

PregS was effective alone and as adjunctive treatment for treating two types of cognitive impairments and negative symptoms in this schizophrenia model. Further study of the mechanisms by which PregS alone and in combination with AAPDs and 5-HT_1A R partial agonists, rescues the deficits in cognition and SI in this preclinical model is indicated.

The Origin of 7α-Hydroxy-Dehydroepiandrosterone and Its Physiological Role: a History of Discoveries

Nearly 60 years has elapsed since the first isolation and identification of 7α-hydroxy-dehydroepiandrosterone, and in that time much information has been gained on its occurrence, metabolism, ontogeny, immunomodulatory activity, cell proliferation, cortisol control in local tissues and neuroactivity. Additional knowledge about this steroid may elucidate its role in obesity, neurodegenerative disturbances such as Alzheimer’s disease, or psychiatric disorders such as schizophrenia or depression. This review aims to provide a comprehensive summary of the available literature on 7α-hydroxy-dehydroepiandrosterone.

Synthesis of 3α-deuterated 7α-hydroxy-DHEA and 7-oxo-DHEA and application in LC-MS/MS plasma analysis

7-Oxygenated metabolites of dehydroepiandrosterone (DHEA) are known for their neuroprotective and immunomodulatory properties. These neuroactive steroids are currently predominately analysed by mass spectrometry, for which the use of internal deuterated standards is necessary. The aim of this study was to synthesize the deuterated derivatives of 7α-hydroxy-DHEA and 7-oxo-DHEA and test them in liquid chromatography-tandem mass spectrometry (LC-MS/MS) in order to enhance the performance characteristics of this method. Here we report the synthesis of 3α deuterium-labelled 7α-hydroxy-DHEA and 7-oxo-DHEA. Deuterium was introduced into the 3α position by reduction of the corresponding 3-ketone with a protected 17-carbonyl group using NaBD4. Our new procedure allows the easier synthesis of deuterated steroid labelled compounds. The use of these deuterated steroids enabled us to improve the human plasma LC-MS/MS analysis of 7α-hydroxy-DHEA and 7-oxo-DHEA in terms of sensitivity, precision and recovery.

A validated LC-MS/MS method for the sensitive quantitation of serum 7alpha hydroxy-, 7beta hydroxy- and 7keto-dehydroepiandrosterone using a novel derivatization reagent

7alpha hydroxy-, 7beta hydroxy- and 7keto-dehydroepiandrosterone (7α OH-DHEA, 7β OH-DHEA and 7 oxo-DHEA) are oxidized metabolites of dehydroepiandrosterone (DHEA). Their concentrations are low in the circulation, especially in postmenopausal women, thus resulting in a considerable challenge for their reliable measurement. A sensitive and accurate LC-MS/MS method has been developed using a simple sample preparation procedure and a novel derivatization with 1-amino-4-methyl piperazine (MP). The derivatized metabolites are stable in high water content reagents. A 10 pg/mL (0.2 pg on column) for the low limit of quantitation (LLOQ) has been achieved for all three compounds. A proper choice of multiple reaction monitoring (MRM) transitions provides good specificity. The excess amount of reagent can be removed from the sample during the derivatization process. Within the calibration range of 10-2000 pg/mL, a good linearity was obtained with R>0.99 where the weighing factor is 1/X while the bias and coefficient of variance (CV) are within 8% for all levels of QCs and calibration curves. This method has been fully validated according to the FDA guidelines, where the results of the matrix effect meet the acceptance criteria while freeze-thaw stability, short and long term stability in matrix and solution as well as post-processed sample stability meet the requirements. With this method, the concentrations of 7α OH-DHEA, 7β OH-DHEA and 7 oxo-DHEA were measured in premenopausal and postmenopausal serum. The average concentration of 7α OH-DHEA is equivalent to that of 7β OH-DHEA in both types of sera.

Steroid Hormones and Homocysteine in the Outcome of Patients With Normal Pressure Hydrocephalus

Normal pressure hydrocephalus (NPH) is one of a few treatable conditions of cognitive decline affecting predominately elderly people. Treatment, commonly based on the ventriculoperitoneal shunt insertion, leads to a partial or complete correction of patient's state, although its effect does not unfortunately always last. The aim of our study was to observe the changes of homocysteine and selected steroids and neurosteroids and follow-up the patients with respect to the duration of the NPH-related dementia improvement. The cerebrospinal fluid and plasma levels of cortisol, cortisone, dehydroepiandrosterone (DHEA), 7α-hydroxy-DHEA, 7β-hydroxy-DHEA, 7-oxo-DHEA, 16α-hydroxy-DHEA (all LC-MS/MS), DHEA-sulphate (DHEAS) (radioimmunoassay) and homocysteine (gas chromatography) were determined in NPH-diagnosed subjects before, during and 6, 12 and 24 months after shunt insertion. The cognitive functions ameliorated after shunt insertion and remain improved within 2 years. Changes in cerebrospinal fluid DHEAS, DHEA and its ratio, cortisone/cortisol and 16α-hydroxy-DHEA and plasma DHEAS, 7β-hydroxy-DHEA, cortisone/cortisol and homocysteine were found. Mentioned changes may contribute to the clarification of NPH pathogenesis. Altered neurosteroids levels are possible indicators to be utilized in the follow-up of NPH subjects. Moreover, plasma homocysteine may serve as an early indicator of NPH-related dementia.

Steroid hormones in prediction of normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) is a treatable neurological disorder affecting elderly people with the prevalence increasing with age. NPH is caused by abnormal cerebrospinal fluid (CSF) reabsorption and manifested as a balance impairment, urinary incontinence and dementia development. These symptoms are potentially reversible if recognized early. Diagnosis of NPH is difficult and can be easily mistaken for other neurodegenerative disorders, which makes NPH one of the major misdiagnosed diseases worldwide. The aim of the study was to find out the appropriate combination of indicators, based on CSF steroids, which would contribute to a clearer NPH diagnosis. The levels of CSF cortisol, cortisone, dehydroepiandrosterone (DHEA), 7α-OH-DHEA, 7β-OH-DHEA, 7-oxo-DHEA, 16α-OH-DHEA and aldosterone (all LC-MS/MS) were determined in our patients (n=30; NPH, 65-80 years) and controls (n=10; 65-80 years). The model of orthogonal projections to latent structures (OPLS) was constructed to predict NPH. Cortisone, 7α-OH-DHEA, 7β-OH-DHEA, 7-oxo-DHEA, aldosterone, 7α-OH-DHEA /DHEA, 7-oxo-DHEA/7α-OH-DHEA, 7β-OH-DHEA/7-oxo-DHEA and 16α-OH-DHEA/DHEA in the CSF were identified as the key predictors and the model discriminated patients from controls with 100% sensitivity and 100% specificity. The suggested model would contribute to early and accurate NPH diagnosis, enabling promptly treatment of the disease.

Dehydroepiandrosterone: a neuroactive steroid

Dehydroepiandrosterone (DHEA) and its sulfate bound form (DHEAS) are important steroids of mainly adrenal origin. They are produced also in gonads and in the brain. Dehydroepiandrosterone easily crosses the brain-blood barrier and in part is also produced locally in the brain tissue. In the brain, DHEA exerts its effects after conversion to either testosterone and dihydrotestosterone or estradiol via androgen and estrogen receptors present in the most parts of the human brain, through mainly non-genomic mechanisms, or eventually indirectly via the effects of its metabolites formed locally in the brain. As a neuroactive hormone, DHEA in co-operation with other hormones and transmitters significantly affects some aspects of human mood, and modifies some features of human emotions and behavior. It has been reported that its administration can increase feelings of well-being and is useful in ameliorating atypical depressive disorders. It has neuroprotective and antiglucocorticoid activity and modifies immune reactions, and some authors have also reported its role in degenerative brain diseases. Here we present a short overview of the possible actions of dehydroepiandrosterone and its sulfate in the brain, calling attention to various mechanisms of their action as neurosteroids and to prospects for the knowledge of their role in brain disorders.

Plasma biomarkers of oxidative stress and genetic variants in age-related macular degeneration

PURPOSE

To compare plasma levels of oxidative stress biomarkers in patients with age-related macular degeneration (AMD) and controls and to evaluate a potential relationship between biochemical markers of oxidative stress and AMD susceptibility genotypes.

DESIGN

Prospective case-control study.

METHODS

Plasma levels of oxidative stress biomarkers were determined in 77 AMD patients and 75 controls recruited from a clinical practice. Cysteine, cystine (CySS), glutathione, isoprostane, and isofuran were measured, and participants were genotyped for polymorphisms in the complement factor H (CFH) and age-related maculopathy susceptibility 2 (ARMS2) genes.

RESULTS

CySS was elevated in cases compared with controls (P = .013). After adjustment for age, sex, and smoking, this association was not significant. In all participants, CySS levels were associated with the CFH polymorphism rs3753394 (P = .028) as well as an 8-allele CFH haplotype (P = .029) after correction for age, gender, and smoking. None of the other plasma markers was related to AMD status in our cohort.

CONCLUSIONS

Our investigation of the gene-environment interaction involved in AMD revealed a relationship between a plasma biomarker of oxidative stress, CySS, and CFH genotype. These data suggest a potential association between inflammatory regulators and redox status in AMD pathogenesis.

Synthesis of a 19-(O-carboxymethyl)oxime hapten of 7β-hydroxy-epiandrosterone

In order to develop an immunoassay of 7β-hydroxy-epiandrosterone, a stereoselective synthesis of a specific hapten, 7β-hydroxy-19-oxo-androstan 19-(O-carboxymethyl)oxime (17), was performed. This synthesis was achieved in 16% overall yield starting from the well-known 3β-acetoxy-19-hydroxy-5-androsten-17-one (1). After coupling of the alkyl oxime moiety, an allylic oxidation of the C-7 carbon under mild conditions followed by two selective reductions established all the functionalities of the final compound 17.

Neurobiological and neuropsychiatric effects of dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS)

DHEA and DHEAS are steroids synthesized in human adrenals, but their function is unclear. In addition to adrenal synthesis, evidence also indicates that DHEA and DHEAS are synthesized in the brain, further suggesting a role of these hormones in brain function and development. Despite intensifying research into the biology of DHEA and DHEAS, many questions concerning their mechanisms of action and their potential involvement in neuropsychiatric illnesses remain unanswered. We review and distill the preclinical and clinical data on DHEA and DHEAS, focusing on (i) biological actions and putative mechanisms of action, (ii) differences in endogenous circulating concentrations in normal subjects and patients with neuropsychiatric diseases, and (iii) the therapeutic potential of DHEA in treating these conditions. Biological actions of DHEA and DHEAS include neuroprotection, neurite growth, and antagonistic effects on oxidants and glucocorticoids. Accumulating data suggest abnormal DHEA and/or DHEAS concentrations in several neuropsychiatric conditions. The evidence that DHEA and DHEAS may be fruitful targets for pharmacotherapy in some conditions is reviewed.

Biomarkers related to aging in human populations

Biomarkers are increasingly employed in empirical studies of human populations to understand physiological processes that change with age, diseases whose onset appears linked to age, and the aging process itself. In this chapter, we describe some of the most commonly used biomarkers in population aging research, including their collection, associations with other markers, and relationships to health outcomes. We discuss biomarkers of the cardiovascular system, metabolic processes, inflammation, activity in the hypothalamic-pituitary axis (HPA) and sympathetic nervous system (SNS), and organ functioning (including kidney, lung, and heart). In addition, we note that markers of functioning of the central nervous system and genetic markers are now becoming part of population measurement. Where possible, we detail interrelationships between these markers by providing correlations between high risk levels of each marker from three population-based surveys: the National Health and Nutrition Examination Survey (NHANES) III, NHANES 1999-2002, and the MacArthur Study of Successful Aging. NHANES III is used instead of NHANES 1999-2002 when specific markers of interest are available only in NHANES III and when we examine the relationship of biomarkers to mortality which is only known for NHANES III. We also describe summary measures combining biomarkers across systems. Finally, we examine associations between individual markers and mortality and provide information about biomarkers of growing interest for future research in population aging and health.

Brain type carnosinase in dementia: a pilot study

Background

The pathological processes underlying dementia are poorly understood and so are the markers which identify them. Carnosinase is a dipeptidase found almost exclusively in brain and serum. Carnosinase and its substrate carnosine have been linked to neuropathophysiological processes.

Methods

Carnosinase activity was measured by a flourometric method in 37 patients attending a Geriatric Outpatient Clinic. There were 17 patients without dementia, 13 had Alzheimer's disease (AD) and 7 had mixed dementia (MD).

Results

The range of serum carnosinase activity for patients without dementia was 14.5 – 78.5 μmol/ml/h. There was no difference in carnosinase activity between patients without dementia (40.3 ± 15.2 μmol/ml/h) and patients with AD (44.4 ± 12.4 μmol/ml/h) or MD (26.6 ± 15 μmol/ml/h). However, levels in the MD group were significantly lower than the AD group (p = 0.01). This difference remained significant after adjusting for gender, MMSE score, exercise, but not age, one at a time and all combined. The effect of other medical conditions did not remove the significance between the AD and MD groups. The MD group, but not the AD group, demonstrated a significant trend with carnosinase activity decreasing with duration of disease (from first recorded date of diagnosis to date of blood collection) (r = -0.76, p = 0.049). There was no association with carnosinase activity and MMSE score in the AD or MD group. Both AD and MD patients on any dementia medication (donepezil, galantamine, memantine) had higher carnosinase activity compared to those not taking a dementia medication. Carnosinase activity was higher in patients who regularly exercised (n = 20) compared to those who did not exercise regularly (n = 17)(p = 0.006).

Conclusion

This exploratory study has shown altered activities of the enzyme carnosinase in patients with dementia.

Plasma growth hormones, P300 event-related potential and test of variables of attention (TOVA) are important neuroendocrinological predictors of early cognitive decline in a clinical setting: evidence supported by structural equation modeling (SEM) parameter estimates

A review of the literature in both animals and humans reveals that changes in sex hormone have often been associated with changes in behavioral and mental abilities. Previously published research from our laboratory, and others, provides strong evidence that P300 (latency) event-related potential (ERP), a marker of neuronal processing speed, is an accurate predictor of early memory impairment in both males and females across a wide age range. It is our hypothesis, given the vast literature on the subject, that coupling growth hormones (insulin-like growth factor-I, (IGF-I) and insulin-like growth factor binding protein 3 (IGF-BP3)), P300 event-related potential and test of variables of attention (TOVA) are important neuroendocrinological predictors of early cognitive decline in a clinical setting. To support this hypothesis, we utilized structural equation modeling (SEM) parameter estimates to determine the relationship between aging and memory, as mediated by growth hormone (GH) levels (indirectly measured through the insulin-like growth factor system), P300 latency and TOVA, putative neurocognitive predictors tested in this study. An SEM was developed hypothesizing a causal directive path, leading from age to memory, mediated by IGF-1 and IGF-BP3, P300 latency (speed), and TOVA decrements. An increase in age was accompanied by a decrease in IGF-1 and IGF-BP3, an increase in P300 latency, a prolongation in TOVA response time, and a decrease in memory functioning. Moreover, independent of age, decreases in IGF-1 and IGF-BP3, were accompanied by increases in P300 latency, and were accompanied by increases in TOVA response time. Finally, increases in P300 latency were accompanied by decreased memory function, both directly and indirectly through mediation of TOVA response time. In summary, this is the first report utilizing SEM to reveal the finding that aging affects memory function negatively through mediation of decreased IGF-1 and IGF-BP3, and increased P300 latency (delayed attention and processing speed).

Estrogen-mediated regulation of CYP7B1: a possible role for controlling DHEA levels in human tissues

The current study examines regulation of CYP7B1, a DHEA 7alpha-hydroxylase, by sex hormones. Transfection with estrogen receptor alpha and treatment with 17beta-estradiol in human embryonic kidney 293 cells significantly increased CYP7B1 catalytic activity and mRNA, and stimulated a human CYP7B1 reporter gene. Transfection with estrogen receptor beta showed similar but less significant effects. In the absence of receptors, 17beta-estradiol suppressed CYP7B1 activity, suggesting that estrogenic effects may be different in cells not expressing receptors. Quantitation of CYP7B1 mRNA in adult and fetal human tissues showed markedly higher CYP7B1 mRNA levels in fetal tissues compared with the corresponding adult ones, except in the liver. This indicates a tissue-specific, developmental regulation of CYP7B1 and suggests an important function for this enzyme in fetal life. DHEA secreted by fetal adrenals is an essential precursor for placental estrogen formation. Since CYP7B1 diverts DHEA from the sex hormone biosynthetic pathway, estrogen receptor-mediated up-regulation of CYP7B1 should lead to less DHEA available for sex hormone synthesis and may help to maintain normal levels of estrogens and androgens in human tissues, especially during fetal development. Regulation by estrogens may also be of importance in other processes where CYP7B1 is involved, including cholesterol homeostasis, cellular proliferation, and CNS function.

Elevated plasma cysteinylglycine levels caused by cilastatin-associated antibiotic treatment

Imipenem (thienamycin formamidine), a broad-spectrum β-lactam antibiotic, is always used in combination with cilastatin in order to avoid the premature breakdown of imipenem by renal tubular dipeptidase. As this dipeptidase also hydrolyzes the glutathione metabolite cysteinylglycine, the therapeutic asso-ciation of imipenem and cilastatin might cause an accumulation of the aminothiol cysteinylglycine. We demonstrate here that when patients are treated with imipenem-cilastatin, their plasma levels of cysteinylglycine are significantly and specifically increased, while cysteine levels are decreased and homocysteine levels are unaffected. We conclude that antibiotic treatment using imipenem-cilastatin induces important metabolic changes that should not remain unrecognized.