Malignant brain tumours associated with adenylate kinase in cerebrospinal fluid

Clinico-pathological correlation in adenylate kinase 5 autoimmune limbic encephalitis

Autoantibodies associated with autoimmune limbic encephalitis (ALE) have been well-characterized, with intracellular neuronal antibodies being less responsive to immunotherapy than antibodies to cell surface antigens. Adenylate kinase 5 (AK5) is a nucleoside monophosphate kinase vital for neuronal-specific metabolism and is located intracellularly in the cytosol and expressed exclusively in the brain. Antibodies to AK5 had been previously identified but were not known to be associated with human disease prior to the report of two patients with AK5-related ALE (Tuzun et al., 2007). We present the complete clinical picture for one of these patients and the first reported neuropathology for AK5 ALE.

Adenylate kinase 5 autoimmunity in treatment refractory limbic encephalitis

We report two men with limbic encephalitis (LE) refractory to corticosteroids, IVIg and plasma exchange. Both patients had serum/CSF antibodies that reacted with the cytoplasm of neurons. Probing of a hippocampal cDNA library resulted in the isolation of adenylate kinase 5 (AK5). Patients' antibodies, but not those of 111 controls, recognized AK5-expressing phage plaques. Human AK5-affinity purified antibodies reproduced the neuronal immunolabeling of patients' antibodies, and co-localized with a rabbit AK5 antibody, confirming that the brain autoantigen was AK5. Detection of antibodies to AK5 in LE patients carries a poor prognosis, and suggests the prompt use of aggressive immunosuppression.

Identification of a novel human adenylate kinase. cDNA cloning, expression analysis, chromosome localization and characterization of the recombinant protein

Adenylate kinases have an important role in the synthesis of adenine nucleotides that are required for cellular metabolism. We report the cDNA cloning of a novel 22-kDa human enzyme that is sequence related to the human adenylate kinases and to UMP/CMP kinase of several species. The enzyme was expressed in Escherichia coli and shown to catalyse phosphorylation of AMP and dAMP with ATP as phosphate donor. When GTP was used as phosphate donor, the enzyme phosphorylated AMP, CMP, and to a small extent dCMP. Expression as a fusion protein with the green fluorescent protein showed that the enzyme is located in the cytosol. Northern blot analysis with mRNA from eight different human tissues demonstrated that the enzyme was expressed exclusively in brain, with two mRNA isoforms of 2.4 and 4.0 kb. The gene that encoded the enzyme was localized to chromosome 1p31. Based on the substrate specificity and the sequence similarity with the previously identified human adenylate kinases, we have named this novel enzyme adenylate kinase 5.

Low frequency of adenylate kinase release into cerebrospinal fluid during balanced, normotensive anaesthesia and a non-orthognathic surgical procedure

Activity of strictly intracellular enzymes in the cerebrospinal fluid (CSF) may indicate leakage from dysfunctional brain cells. Increased activity of adenylate kinase (AK) in the CSF is indicative of brain cell injury arising from several sources, among them orthognathic surgery. The mechanism in the latter case is obscure, but the use of an oscillating saw which generates vibrations, and the site of surgery close to the brain may be contributing factors. Anaesthesia may also play a role. In the present study, CSF-AK activity was measured after hysterectomy and was compared with activity after orthognathic surgery in two other studies. Four of 19 patients (21%) in the present study expressed pathological activity, compared with 34 of 47 (72%) orthognathic patients in the two other studies. No firm conclusion may be drawn from historical comparisons, and the difference in activity seen between the two types of surgery might not necessarily be the result of surgical factors. Until this is investigated further, however, we conclude that there may be a difference in postoperative CSF-AK activity between orthognathic and lower abdominal surgery.

Markers of cerebral ischemia after cardiac surgery

The objective of this review is to provide an overview of the use of biochemical markers for the detection of Central Nervous System (CNS) complications after cardiac surgery and extracorporeal circulation (ECC). A computerized literature search in MEDLINE from 1966 onward was the basis for the references. The literature covering the following biochemical markers is reviewed: adenylkinase, creatine phosphokinase isoenzyme BB (CK-BB), lactate, neuron-specific enolase (NSE), S-100 protein, myelin basic protein, lactate dehydrogenase, aspartate aminotransferase, glutathione, vasointestinal neuropeptide, and 7B2-specific neuropeptide. For clinical purposes, it is necessary to have a biochemical marker that can be measured in blood. Lactate, although a primary marker of anaerobic metabolism, and CK-BB values, calculated from the arterio-internal jugular venous difference, appear to correlate with periods of ischemia during ECC. S-100 protein levels have been shown to correlate with duration of ECC, and when combined with NSE values, could be used to identify patients with CNS dysfunction after cardiac surgery. The use of NSE may be limited by its presence in erythrocytes and platelets because the high levels that can result from hemolysis can render it less specific. Although recently introduced, S-100 protein may have the potential to be a valuable marker for CNS dysfunction after ECC.

A unifying model of the cell proliferation emphasizing plasma membrane fluxes

The regulation of cellular growth and proliferation is perhaps the most investigated and elusive problem in cell biology and seems to be possible to solve from almost any angle of study chosen. Among the non-systemic factors that have been discussed are genetic damage, genomic control, regulation by stimulatory and inhibitory peptide factors such as EGF, chalones, and fibronectin, protein kinase activation with tyrosine phosphorylation, adenylylcyclase and cAMP, cGMP, membrane perturbations and specifically in tumours the failure of the Pasteur effect in control of glycolysis, excessive membrane ATPase activity, and excessive hydrolytic and proteolytic activities at the cell surface. This article focuses on the central role of fluxes within the plasma membrane and re-examines the possibility that changes of flux of metabolites, ions, and reducing equivalents may be the common denominator regulating cellular proliferation.

Reversible brain cell damage due to hypoglycemia in a patient with insulinoma

A case of an insulinoma with hypoglycemic attacks accompanied by episodes of unconsciousness in a 57-year-old woman is described. During the hypoglycemic spells the level of adenylate kinase (AK) in the cerebrospinal fluid (CSF) was elevated 6-fold above the normalized level obtained later from the patient being in a normoglycemic condition. CSF-AK was previously found to be a sensitive marker of subtle brain cell damage due to hypoxia. The increased efflux of AK into CSF during the insulinoma-induced hypoglycemia was most probably the result of a brain cell injury caused by shortage of glycolytic fuel.

Adenylate kinase enzyme activity in cases of brain infarction

The adenylate kinase (AK) enzyme activity in plasma and CSF of acute brain infarctions was examined. The normal values of enzyme activity in plasma reached from 1.7-5.6 U/l, and in CSF from 0.23-0.71 U/l. According to this present classification a significant CSF increase in AK activity was found with semi-severe and severe brain infarctions. With the CCT an increased enzyme activity was shown with infarction in or close to the cortex. In no case was an alteration of AK activity in the serum sample. CSF samples showing blood contamination or pleocytosis led to false pathological results with examination of AK activity.

Cerebral damage during open-heart surgery. Clinical, psychometric, biochemical and CT data

The incidence and extent of cerebral damage following open-heart surgery were prospectively investigated in 103 patients, using clinical assessment, psychometry, adenylate kinase analysis in cerebrospinal fluid (CSF-AK) and computed tomography (CT) of the brain. The surgical mortality was 1.9%. Clinically there was obvious cerebral dysfunction in four cases, subtle evidence of brain damage (mainly undue fatigue) in 16 and no evidence in 81 cases. In the 16 patients the mean CSF-AK was substantially increased (0.122 U/l) and the psychometric performance distinctly impaired (-12 points) postoperatively; in the 81 patients the figures were 0.55 U/l and -3.4. Psychometrically, 60% of the patients showed cerebral dysfunction, which was pronounced in 16%. CSF-AK analysis indicated cerebral damage as absent or trival in 45%, moderate in 33% and marked in 22%. CT revealed postoperative cerebral infarction in two cases. Results from the various methods showed reasonable correlation, but also considerable overlap. Open-heart surgery thus can cause brain damage additional to that neurologically discernible. Fatigue is an important sign in this context. In research on postoperative brain damage, the relative insensitivity of routine neurologic investigation calls for supplementary, refined methods.

CSF cyclic AMP and CSF adenylate kinase in cerebral ischaemic infarction

The severity of neurological deficits, size of hypodense zone on CT, concentration of cAMP and activity of adenylate kinase in cerebrospinal fluid (CSF) were evaluated at predefined intervals in the acute stage of supratentorial cerebral ischaemic infarction in 52 patients. Patients with cerebral infarction had raised activities of adenylate kinase CSF as compared with normal persons. Patients with marked neurological deficits, only slight improvement of neurological signs and large infarction zones on CT had higher average activities of adenylate kinase and lower concentration of cAMP in CSF. Alterations of CSF adenylate kinase and CSF cAMP values were most distinct on the 3rd day after the stroke. Reasons for the changes may be metabolic disorders following brain ischaemia.

Deoxythymidine-kinase in cerebrospinal fluid: a new potential "marker" for brain tumours

A recently developed method for deoxythymidine kinase (dTK) determination was applied to cerebrospinal fluid (CSF) and serum samples, derived from "healthy" individuals and from patients with non-neoplastic or neoplastic disorders of the brain. No dTK activity could be detected in the CSF of healthy individuals or in patients with hydrocephalus or cranio-cerebral trauma. dTK levels ranging from detectable to high were found in the CSF of patients with malignant primary brain tumours or secondary brain tumours, while in some cases of low grade primary brain tumours dTK could not be detected in the CSF. CSF samples taken before and after treatment were available both in some patients with CNS involvement of malignant lymphomas and in some with primary brain tumours. The dTK activity rapidly declined after chemotherapy intrathecally and irradiation, as well as after surgery. Enhanced CSF dTK was not only a feature of malignant CNS processes, but was also found in patients with cerebral haemorrhage penetrating into the CSF. The origin of dTK in CSF and the practical use of quantifying it is discussed.

Cerebrospinal fluid markers of disturbed brain cell metabolism

Reversibly and irreversibly disturbed brain cell metabolism may be monitored in an indirect way by the analyses of enzymes in the CSF according to the hypothesis of cell swelling induced by energy shortage. Adenylate kinase fulfils the criteria for an ideal CSF marker with the exception that it is not organspecific, which necessitates precautions to avoid influence of AK in erythrocytes and serum. When taking such limitating factors into account, AK determinations may be diagnostically useful in combination with radiological and clinical observations. Besides, it is possible that a combination of AK analyses and clinical signs are useful in the prognostication in individual patients suffering from global cerebral ischemia and cerebral infarction.

Cerebrospinal fluid enzymes in neurological diseases

The activities of adenylate kinase, creatine kinase and lactate dehydrogenase were measured in cerebrospinal fluid and serum from 127 patients admitted to the Department of Neurology. All cerebrospinal fluid samples with hemoglobin greater than 1 mg/l were excluded. Upper reference limits for the enzyme determinations were established, using samples from patients without objective criteria of organic involvement of the nervous system. High enzyme activities did not correlate to any particular group of diseases and were also found in patients without organic brain diseases. We conclude that determination of the three enzymes in cerebrospinal fluid is of limited value in the diagnosis of neurological diseases.

Adenylate kinase activity in cerebrospinal fluid of schizophrenic and certain other psychiatric symptomatologies

Adenylate kinase activity in the cerebrospinal fluid (CSF) was investigated in 29 patients with psychiatric symptomatologies. Such activity was demonstrated in 18 of the 19 individuals with schizophrenic or other psychotic or borderline psychotic symptomatology. No activity was seen in the remaining 10 patients with non-psychotic nervous and/or functional somatic complaints, nor in the 20 persons whose CSF was examined in connection with spinal anaesthesia, nor in four who were treated with neuroleptic drugs on nonpsychiatric indications. The findings are compatible with the assumption that in persons with psychotic or borderline psychotic symptomatology a lowered membrane electrochemical potential may be associated with some of the symptoms exhibited.

Cerebrospinal fluid content of adenylate kinase, lactate and glutathione in patients with meningitis

Adenylate kinase activity and lactate concentration were measured in the cerebrospinal fluid (CSF) of 5 patients with bacterial meningitis, of 4 patients with probable bacterial meningitis, and of 18 patients with serous meningitis. Furthermore, for comparison measurements were also performed in CSF of 27 patients with meningism. Concomitantly glutathione was measured in CSF in most of the patients. Significantly higher values of these 3 parameters were found in the CSF of patients with bacterial and probable bacterial meningitis compared with those having serous meningitis and meningism. Adenylate kinase activity and lactate concentration in patients with serous meningitis were significantly higher than in those with meningism. All patients with a clinical diagnosis of meningitis studied so far also displayed an adenylate kinase activity in their CSF. The determination of adenylate kinase, lactate and glutathione levels in CSF might be a useful aid for the diagnosis not only of meningitis but also for the discrimination between bacterial and serous meningitis.