Age-related change in 7B2 (a novel pituitary polypeptide) concentrations in human cerebrospinal fluid

Concentrations of 7B2 (a novel pituitary polypeptide) immunoreactivity (7B2-IR) were measured using a specific 7B2 radioimmunoassay (RIA) in cerebrospinal fluids (CSFs) from 87 humans. The mean (+/- S.E.M.) concentration of 7B2-IR in CSF was 2022 +/- 68 pM and a statistically significant decrease with aging was observed in those concentrations (R = -0.28, t = 2.73, P less than 0.01), although it was not a strong relation based on the R-value. In the gel permeation chromatography of CSF on Sephadex G-100, a major peak with an apparent mol. wt. of 43 kDa (43K) and a minor peak with that of 11 kDa (11K) were observed.     

Plasma 7B2 (a novel pituitary protein) immunoreactivity concentrations in patients with various endocrine disorders

We have measured plasma 7B2 (a novel pituitary protein)-immunoreactivity (IR) concentrations in patients with various endocrine disorders. Mean (+/- SEM) basal plasma 7B2-IR concentrations (ng/L) in patients with acromegaly (81 +/- 14.6), Cushing's disease (57.2 +/- 8.5), prolactinoma (71.4 +/- 9.5), panhypopituitarism (50.6 +/- 7.6), isolated ACTH deficiency (47.9 +/- 11.6), hyperthyroidism (57.9 +/- 6.7) and hypothyroidism (60.8 +/- 9.4) were on the same levels as those in age-matched normal subjects. However, basal plasma 7B2-IR concentrations were increased to more than 100 ng/L in 5 out of 25 patients with acromegaly (20%). Mean basal plasma 7B2-IR concentrations in patients with medullary carcinoma of the thyroid and pheochromocytoma were 293 +/- 38.1 ng/L (range: 225.7-357.4 ng/L, n = 3) and 221 +/- 82.8 ng/L (range: 48.5-527.8 ng/L, n = 5), respectively, and significantly higher than those in age-matched normal subjects (P less than 0.001). These results suggest that plasma 7B2-IR may have some diagnostic value for acromegaly and may be useful as a marker for medullary carcinoma of the thyroid and pheochromocytoma.     

Ontogeny of a novel pituitary protein (7B2) in the human fetal intestine

The developmental profile of the concentration of a novel pituitary protein (7B2) was studied immunochemically in the human gastrointestinal tract from 12 weeks of gestation to 4 months after birth and was compared to the distribution in the adult. 7B2-like immunoreactivity (IR-7B2) was detected in all segments studied, but no gross changes were seen through fetal life. At term higher concentrations of IR-7B2 were found in the duodenum and the antrum, which is similar to the distribution of adult man. Gel permeation chromatography revealed that the main peak of 7B2 immunoreactivity in the fetal intestinal extract eluted with a Kav of 0.3. Similar elution profiles were also observed in extracts of human adult intestine.     

Immunocytochemical localization of a novel pituitary protein (7B2) within the rat brain and hypophysis

A novel pituitary protein called 7B2 was localized in rat pituitary and brain by immunocytochemistry (unlabeled antibody technique). Immunoreactive material was present in the secretory cells of anterior and intermediate lobes and in neural structures of the posterior lobe of the hypophysis. 7B2-immunoreactive neurons were evident within the hypothalamus in the supraoptic nucleus, paraventricular nucleus (magnocellular and parvocellular parts), and lateral hypothalamus. Immunoreactive nerve fibers were seen within the internal and external zone of the median eminence. Among extrahypothalamic regions, the substantia nigra, dorsal tegmental nucleus, cuneiform nucleus, dorsal parabrachial nucleus, spinal tract trigeminal nerve, interior olive, solitary nucleus, and layers I and II of the spinal cord contained 7B2-immunoreactive material. This anatomical distribution suggests a role for 7B2 in endocrine and autonomic functions.     

Vitamin E concentrations in human brain of patients with Alzheimer's disease,fetuses with Down's syndrome,centenarians, and controls

The concentration of vitamin E (alpha-tocopherol) was measured in samples of cortex from patients with Alzheimer's disease (AD), fetuses with Down's syndrome (DS), and also in a group of centenarians. The mean tocopherol concentrations in the two patient groups did not differ significantly from appropriate controls. When expressed per lipid the mean tocopherol concentration of the centenarians was greater than that of the controls but this reflected a significant decrease in the lipid concentration of the former group. These results indicate that neither the normal aging processes, Alzheimer's disease, nor the increased in vitro lipid peroxidation reported in fetuses with Down's syndrome result from a gross lack of alpha-tocopherol, or cause a significant depletion of the vitamin.     

Beta-amyloid (Abeta) protein in cerebrospinal fluid as a biomarker for Alzheimer's disease

With the arrival of symptomatic treatment (acetylcholine esterase inhibitors) and the promise of drugs that may delay disease progression, development of diagnostic biomarkers for Alzheimer's disease (AD) are important. Beta-Amyloid (Abeta) protein is the main component of senile plaques. A marked reduction in cerebrospinal fluid (CSF)-Abeta42 in AD has been found in numerous studies. Importantly, reduced CSF-Abeta42 is also found very early in the disease process, before the onset of clinical symptoms. Recent studies suggest that CSF-Abeta42 have a satisfactory performance when used as a diagnostic marker for AD in clinical routine. This paper reviews CSF-Abeta42 as a biomarker for AD.     

Elevation of plasma 7B2 (a novel pituitary protein) in cord blood at obstetrical delivery and the possible correlation with GH

Plasma 7B2-immunoreactivity (7B2-IR) concentrations in umbilical artery (UA), umbilical vein (UV) and maternal vein (MV) were measured by RIA at the time of obstetrical delivery at term. Plasma 7B2-IR concentrations (Mean +/- SEM) in UA (N = 12), UV (N = 16) and MV (N = 16) were 725 +/- 69, 699 +/- 64 and 116 +/- 4.5 pg/ml, respectively. Plasma 7B2-IR concentrations in UA and UV were much higher than those in MV. There was no arterio-venous gradient between UA and UV. A trace amount of 7B2-IR (Mean +/- SEM, 226 +/- 16.8 pg/g tissue) was detected in the placental extracts. A statistically significant positive correlation (r = 0.7595, p less than 0.005) was found between plasma 7B2-IR and GH in the UV. Significant negative correlations between body weight of the neonates and plasma levels of GH (r = -0.6836, p less than 0.01) and 7B2-IR (r = -0.4939, p less than 0.05) were also apparent. When analyzing cord blood plasma using gel permeation chromatography and SDS-polyacrylamide gel electrophoresis, a major peak with an apparent molecular weight of 20,000 was observed. These findings suggest that 7B2-IR in UA and UV originates from the fetus and that 7B2-IR does not permeate through the placenta. The possibility of involvement of 7B2 in fetal growth warrants attention.     

Apolipoprotein E (apoE) polymorphism and its influence on ApoE concentrations in the cerebrospinal fluid in Finnish patients with Alzheimer's disease

The apoE phenotype of 83 patients with probable Alzheimer's disease (AD) and of 164 non-demented controls was determined by isoelectric focusing and Western blotting. The proportion of the e4 allele was 0.548 in AD and 0.202 in controls (P<0.0001). The effect was seen in both early-onset and late-onset AD patients. The risk of AD in 4 homozygotes was 18-fold greater than in individuals without the 4 allele. ApoE concentrations were measured in serum and cerebrospinal fluid (CSF) from a subgroup of patients with AD (n=72) and controls (n=84) by a sandwich enzyme-linked immunosorbent assay. Although serum apoE concentrations were lower in individuals with the 4 allele than in those without the e4 allele, CSF apoE concentrations did not vary in different phenotype groups. However, CSF apoE levels were lower in AD patients than in controls. We conclude that the inheritance of the 4 allele of apoE is a risk factor for AD in the Finnish population.     

Age-related change in plasma concentration of 7B2 (a novel pituitary polypeptide) in normal humans

Using a specific radioimmunoassay, we measured concentrations of plasma 7B2 (a novel pituitary polypeptide) immunoreactivity (7B2-IR) in normal human subjects, patients with chronic renal failure and those with liver cirrhosis. Mean (+/- SEM) values of plasma 7B2-IR in normal healthy men and women were 55.8 +/- 1.2 pg/ml (n = 266) and 56.1 +/- 0.9 pg/ml (n = 408), respectively. The elevation of plasma 7B2-IR showed a relationship with age of the subjects, in both men (r = 0.39, t = 6.86, p less than 0.001) and women (r = 0.35, t = 7.44, p less than 0.001). Plasma 7B2-IR concentrations were elevated in patients with chronic renal failure (536 +/- 45 pg/ml, Mean +/- SEM, n = 10) as well as those in liver cirrhosis (95 +/- 10 pg/ml, Mean +/- SEM, n = 15) compared to values in normal subjects, suggesting that 7B2 is mainly eliminated through the kidney and is partly metabolized in the liver.     

The novel pituitary polypeptide 7B2 is a highly-conserved protein coexpressed with proopiomelanocortin

In the amphibian intermediate pituitary gland the biosynthetic activity for production of the precursor protein proopiomelanocortin (POMC) can be physiologically manipulated; POMC synthesis is high in animals adapted to a black background and low in white-adapted animals. In order to study genes associated with POMC gene expression we applied a differential hybridization technique involving screening of a pituitary cDNA library with probes derived from RNA of inactive and physiologically activated intermediate pituitary cells of the amphibian Xenopus laevis. A differentially hybridizing Xenopus pituitary cDNA clone encoded the novel polypeptide 7B2. This Mr-21,000 secretory granule-associated protein of unknown function is shown to be highly conserved between Xenopus and human (83% amino acid sequence similarity). Conserved segments within the 7B2 structure included the N-terminal portion, three pairs of basic amino acids which are potential recognition sites for proteolytic enzymes, and three regions sharing similarity with putative GTP-binding domains. Levels of 7B2 mRNA were about 3% of POMC mRNA levels in Xenopus pituitary glands. In the intermediate pituitary the amount of both POMC and 7B2 mRNA was much higher in black-adapted toads than in white-adapted animals. These physiologically-induced changes in POMC and 7B2 mRNA levels were not found in the anterior pituitary. We conclude that the POMC and 7B2 genes are coexpressed and that modulation of the activity of these genes is tissue-specific.     

5-Hydroxyindoleacetic acid and homovanillic acid concentrations in cerebrospinal fluid in patients with Alzheimer's disease, depression and mild cognitive impairment

In this study we investigated the cerebrospinal fluid (CSF) concentrations of 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) in Alzheimer (AD) patients (n=75), patients with mild cognitive impairment (MCI, n=9) and patients with depression (n=7). CSF HVA was significantly elevated in AD with depression (Geriatric Depression Scale, 15 point version GDS>5) in comparison to AD without depression (p<0.05, ANOVA) and CSF HVA showed a significant positive correlation with the GDS score of AD-patients (p=0.03, Spearman Rho: 0.38, Spearman Rank Correlation). In the group of AD patients CSF 5-HIAA was positively correlated with cerebrospinal fluid beta-amyloid 1-42 (Abeta42), p<0.05, Spearman Rho: 0.3, Spearman Rank Correlation, but not with CSF tau. Additionally, there was a significant positive correlation between cerebrospinal fluid 5-HIAA and HVA in the group of AD patients (p<0.0001, Rho: 0.47, Spearman Rank correlation). Neither 5-HIAA nor HVA in CSF could differentiate between mild cognitive impairment, depression and AD. The results of this study support the hypothesis that the serotonergic system plays a role in the course of AD. They further suggest an important role of dopamine metabolism in depression within AD patients.     

Molecular isoform distribution and glycosylation of acetylcholinesterase are altered in brain and cerebrospinal fluid of patients with Alzheimer's disease

The glycosylation of acetylcholinesterase (AChE) in CSF was analyzed by lectin binding. AChE from Alzheimer's disease (AD) patients was found to bind differently to two lectins, concanavalin A and wheat germ agglutinin, than AChE from controls. As multiple isoforms of AChE are present in both CSF and brain, we examined whether the abnormal glycosylation of AD AChE was due to changes in a specific molecular isoform. Globular amphiphilic dimeric (G2a) and monomeric (G1a) isoforms of AChE were found to be differentially glycosylated in AD CSF. Glycosylation of AChE was also altered in AD frontal cortex but not in cerebellum and was also associated with an increase in the proportion of light (G2 and G1) isoforms. This study demonstrates that the glycosylation of AChE is altered in the AD brain and that changes in AChE glycosylation in AD CSF may reflect changes in the distribution of brain isoforms. The study also suggests that glycosylation of AChE may be a useful diagnostic marker for AD.     

Increase of total homocysteine concentration in cerebrospinal fluid in patients with Alzheimer's disease and Parkinson's disease

We determined the concentrations of free homocysteine (HC) and total HC in the cerebrospinal fluid (CSF) of patients with Alzheimer's disease (AD) or Parkinson's disease (PD) in order to elucidate whether HC is related to the pathogenesis of these neurodegenerative diseases. The concentration of free HC did not differ significantly from that of the normal controls, while the concentration of total HC was significantly higher in the AD and PD patients (+31% in AD,+31% in PD; p<0.05). These findings suggest that an increase of total HC concentration in the brain is commonly seen in patients with AD and PD, and this may be related to the pathogenesis of these two diseases.     

Purine and pyrimidine base and nucleoside concentrations in human cerebrospinal fluid and plasma

Purine and pyrimidine base and nucleoside levels were determined in adult human lumbar (CSF) and plasma by reversed-phase high performance liquid chromatography (HPLC). Guanine, thymine, cytosine and uracil were not detectable (<0.1 M) in human CSF or plasma. Adenine was detectable in plasma (0.3 M) but was not found in CSF (<0.2 M). Hypoxanthine and xanthine levels in CSF were each approximately 2.5 M. Plasma levels of hypoxanthine and xanthine were considerably lower (0.4–0.6 M). Purine and pyrimidine ribouncleosides in human CSF were less than or equal to 0.2 M with the exception of uridine which was present at concentrations of 2–3 M. Although low concentrations of thymidine and deoxyuridine (0.2 M) were present in human plasma, purine and pyrimidine deoxyribonucleosides were less than 0.1 M in human lumbar CSF.     

Dipeptidyl-aminopeptidase II in human cerebrospinal fluid: changes in patients with Parkinson's disease

By using a sensitive and specific method, DAP II activity was found in CSF. DAP II activity in CSF of control patients without neurological diseases was 0.416 +/- 0.141 (mean +/- SD) nmole/min/ml and was higher than DAP IV activity in CSF, 0.221 +/- 0.062 (mean +/- SD) nmole/min/ml. In contrast, DAP II activity in serum was 1.16 +/- 0.16 (mean +/- SD) nmole/min/ml and was lower than serum DAP IV activity [41.85 +/- 3.36 (mean +/- SD) nmole/min/ml]. This relatively high activity of DAP II in CSF compared with the activity of DAP IV in CSF together with recent histochemical evidence on the localization of DAP II in some neurons (7) suggests that CSF DAP II may be derived from the brain and may be a marker of some peptidergic neurons. DAP II activity in CSF of patients with Parkinson's disease was significantly increased, whereas DAP IV activity in CSF did not change significantly.     

Plasma levels of 7B2 (a novel pituitary polypeptide) and its molecular forms in plasma and urine in patients with chronic renal failure: possible degradation by the kidney

Plasma immunoreactive (IR)-7B2 was measured in patients with chronic renal failure (CRF), using a specific radioimmunoassay. The mean (+/- S.E.M.) concentration of plasma IR-7B2 in CRF patients under hemodialysis (502 +/- 36 pg/ml, n = 27) was significantly higher than that in normal subjects (men, 52.9 +/- 1.7 pg/ml (n = 179); women, 55.8 +/- 1.3 pg/ml (n = 198]. Significant correlations between plasma levels of IR-7B2 and those of blood urea nitrogen, creatinine and beta 2-microglobulin were evident in non-dialyzed CRF patients. In the analyses of pooled plasma and urine obtained from normal subjects on gel permeation chromatography, a major peak of IR-7B2 was observed at an apparent molecular weight of 20,000 in the plasma, and at a position of a smaller molecular weight in the urine. These results suggest that 7B2 is degraded mainly in the kidney and that measurement of plasma 7B2 may serve as an appropriate tool for assessing renal function.     

Effect of LHRH on plasma 7B2 in patients with gonadotropin-producing pituitary adenomas.

Plasma immunoreactive (IR)-7B2 was measured in four patients with gonadotropin-producing pituitary adenomas. The basal level of plasma IR-7B2 was elevated in one of the four patients. Hyperresponse of plasma IR-7B2 to LHRH or LHRH/TRH was noted in two patients tested. 7B2 was positively stained in a paraffin-embedded section of gonadotropin-producing pituitary adenoma obtained at surgery. These findings suggest that 7B2 is produced in gonadotropin-producing pituitary adenomas and secreted into the blood stream under certain conditions. 7B2 may be a useful marker for gonadotropin-producing pituitary adenomas.     

Alterations in cerebrospinal fluid glycerophospholipids and phospholipase A2 activity in Alzheimer's disease

Our aim is to study selected cerebrospinal fluid (CSF) glycerophospholipids (GP) that are important in brain pathophysiology. We recruited cognitively healthy (CH), minimally cognitively impaired (MCI), and late onset Alzheimer''s disease (LOAD) study participants and collected their CSF. After fractionation into nanometer particles (NP) and supernatant fluids (SF), we studied the lipid composition of these compartments. LC-MS/MS studies reveal that both CSF fractions from CH subjects have N-acyl phosphatidylethanolamine, 1-radyl-2-acyl-sn-glycerophosphoethanolamine (PE), 1-radyl-2-acyl-sn-glycerophosphocholine (PC), 1,2-diacyl-sn-glycerophosphoserine (PS), platelet-activating factor-like lipids, and lysophosphatidylcholine (LPC). In the NP fraction, GPs are enriched with a mixture of saturated, monounsaturated, and polyunsaturated fatty acid species, while PE and PS in the SF fractions are enriched with PUFA-containing molecular species. PC, PE, and PS levels in CSF fractions decrease progressively in participants from CH to MCI, and then to LOAD. Whereas most PC species decrease equally in LOAD, plasmalogen species account for most of the decrease in PE. A significant increase in the LPC-to-PC ratio and PLA₂ activity accompanies the GP decrease in LOAD. These studies reveal that CSF supernatant fluid and nanometer particles have different GP composition, and that PLA₂ activity accounts for altered GPs in these fractions as neurodegeneration progresses.     

Detection of amyloid beta protein precursor immunoreactivity in normal and Alzheimer's disease cerebrospinal fluid

The amyloid A4 (or beta protein), a 4.2 kD polypeptide, is a major component of amyloid deposits in the brains of patients with Alzheimer's Disease (AD). The self-aggregating amyloid A4 protein of AD is encoded as part of three larger proteins by the amyloid A4 precursor gene. The corresponding proteins have 695, 751 and 770 amino acid residues. To investigate the utility of amyloid beta protein precursor (A beta PP) as a diagnostic marker for AD an antiserum against a synthetic peptide (175-186), predicted from cDNA sequence for A beta PP, was used. The immunoreactivity of A beta PP in normal and AD cerebrospinal fluid (CSF) was measured by Western blot and detected with radiolabeled protein A. A total of fifty-seven CSF samples (AD = 27 and normal = 30) were analyzed for A beta PP immunoreactivity. A polyclonal antibody detected two major protein bands with apparent molecular weights of 105kD and 90kD both in normal and AD CSF. The difference between normal and AD CSF was not significant. These results indicate that immunoreactivity of A beta PP is present both in normal and AD CSF, and that the difference is too small to be used as a diagnostic marker.     

beta-Trace protein in human cerebrospinal fluid: a diagnostic marker for N-glycosylation defects in brain.

As carbohydrate-deficient glycoprotein syndromes (CDGS) are multisystemic disorders with impaired central nervous function in nearly all cases, we tested isoforms of beta-trace protein (beta TP), a 'brain-type' glycosylated protein in cerebrospinal fluid (CSF) of nine patients with the characteristic CDGS type I pattern of serum transferrin. Whereas the serum transferrin pattern did not discriminate between the various subtypes of CDGS type I (CDGS type Ia, type Ic, and patients with unknown defect), beta TP isoforms of CDGS type Ia patients differed from that of the other CDGS type I patients. The percentage of abnormal beta TP isoforms correlated with the severity of the neurological symptoms. Furthermore, two patients are described, who illustrate that abnormal protein N-glycosylation can occur restricted to either the 'peripheral' serum or the central nervous system compartment. This is the first report presenting evidence for an N-glycosylation defect restricted to the brain. Testing beta TP isoforms is a useful tool to detect protein N-glycosylation disorders in the central nervous system.