Cerebrospinal fluid protein markers in PD patients after DBS-STN surgery-A retrospective analysis of patients that underwent surgery between 1993 and 2001.

OBJECTIVE: Cerebrospinal fluid (CSF) markers of neurodegeneration [neurofilament light chain (NFL), total Tau (T-Tau)], tau pathology [phosphorylated tau (p-Tau)], glial cell damage or activation [glial fibrillary acidic protein (GFAP)], and brain amyloidosis [ß-amyloid 1-42 (Aß42)] are useful for diagnosis and prognosis in several neurodegenerative disorders. In this paper we investigate these markers and their relationship to key clinical milestones in patients with advanced Parkinson´s disease (PD) operated at our center with subthalamic nucleus deep brain stimulation (STN-DBS) for at least 15 years ago. PATIENTS AND METHODS: Retrospective analysis of available cerebrospinal fluid and clinical data in PD-patients, 15 years or more after they underwent STN-DBS surgery. All PD-patients implanted with STN-DBS at Sahlgrenska University Hospital before January 1, 2001, were regularly assessed until January 10, 2018, or until death, or until lost to follow-up. RESULTS: Twenty three PD patients were operated with STN-DBS. Sixteen of these (six females and ten males) underwent at least one lumbar puncture (LP) immediately prior to or after STN-DBS. Their age at the latest available LP was 64 (55-75) years [median (range)], PD duration 20 (11-33) years, and Hoehn & Yahr (H&Y) stage 3 (2-4). Time between DBS operation and the last LP was 4.5 (0.3-10.8) years. Time from the last LP to the last follow up was 6 (0.1-18) years, and for the entire cohort 115 person-years. On January 10, 2018, four PD-patients (25%) were still alive. All preoperative CSF marker levels were normal. Between two days and six months after DBS, NFL and GFAP levels increased sharply but they normalized thereafter in most patients, and were normal up to almost 11 years after neurosurgery. Over time, all patients deteriorated slowly. At the last follow up, H&Y was 5 (3-5) and 12/16 were demented. There was no significant correlation between postoperative (> 6 months) CSF NFL, GFAP, T-Tau, p-Tau, ß-amyloid levels and the presence of dementia, psychosis, inability to walk or need for nursing home at the time for LP, nor for presence of dementia at the last follow up or for death as of January 10, 2018. CONCLUSION: CSF protein biomarkers remain normal despite long PD duration, severe disability, and chronic STN-DBS. They cannot be used for PD staging or prognostication but may indicate brain damage caused by other pathological factors.

Cerebrospinal fluid markers of neuronal and glial cell damage in patients with autoimmune neurologic syndromes with and without underlying malignancies.

Autoimmune neurologic syndromes can be paraneoplastic (associated with malignancies and/or onconeural antibodies), or non-paraneoplastic. Their clinical presentation is often similar. As prognosis is related to malignancy treatment, better biomarkers are needed to identify patients with malignancy. We investigated cerebrospinal fluid (CSF) markers of neuronal (neurofilament light chain, NFL and total tau protein, T-tau) and glial (glial fibrillary acidic protein) damage. CSF-NFL and T-tau were increased in both paraneoplastic and non-paraneoplastic autoimmune syndromes. Patients with manifest malignancies were older, had less epilepsy, more focal central and peripheral neurological signs and symptoms, and worse long-term outcome, than those without malignancy. CSF-NFL-levels predicted long-term outcome but were not diagnostic for malignancy, after age adjustment.

Higher CSF interleukin-6 and CSF interleukin-8 in current depression in older women. Results from a population-based sample.

OBJECTIVE: The literature regarding cerebrospinal fluid (CSF) cytokines in geriatric depression is sparse. The aim of this study was to examine associations between CSF interleukin-6 (IL-6), interleukin-8 (IL-8) and depression in a population-based sample of older women who were followed for 17 years. METHODS: 86 dementia-free women aged 70-84 years who participated in the Prospective Population Study of Women in Gothenburg, Sweden took part in a lumbar puncture in 1992-3. CSF IL-6 and CSF IL-8 were measured. Psychiatric symptoms were rated with the Comprehensive Psychopathological Rating Scale at baseline and at three subsequent face-to-face examinations. Depression (major or minor) was diagnosed in accordance with DSM-IV/DSM-IV research criteria. RESULTS: At baseline, women with ongoing major (n=10) or minor depression (n=9) had higher levels of CSF IL-6 (p=0.008) and CSF IL-8 (p=0.007) compared with those without depression (n=67). Higher CSF IL-8 was related to higher MADRS score (p=0.003). New cases of depression were observed in 9 women during follow-ups. No associations between CSF cytokine levels and future depression could be shown in women without depression at baseline. CONCLUSION: Higher levels of CSF IL-6 and IL-8 were associated with current depression in this population-based sample. CSF IL-6 and CSF IL-8 may play a role in depression in late life.

Lower CSF interleukin-6 predicts future depression in a population-based sample of older women followed for 17 years.

OBJECTIVE: The literature regarding cerebrospinal fluid (CSF) cytokines in geriatric depression is sparse. The aim of this study was to examine associations between CSF interleukin-6 (IL-6) and related proinflammatory cytokines and current and future depression in a population-based sample of older women who were followed for 17 years. METHODS: 83 non-demented women aged 70-84 years who participated in the Prospective Population Study of Women in Gothenburg, Sweden took part in a lumbar puncture in 1992-3. CSF- IL-6, interleukin-1ß (IL-1ß), interleukin- 8 (IL-8) and tumor necrosis factor-α (TNF-α) were measured. Psychiatric symptoms were rated with the Comprehensive Psychopathological Rating Scale at baseline and at three subsequent face-to-face examinations. Depression (major or minor) was diagnosed in accordance with DSM-IV/DSM-IV research criteria. RESULTS: At baseline, women with ongoing depression had lower levels of IL-6 (p<0.04), IL-8 (p<0.05) and TNF-α (p<0.05) compared with those without depression. In women without depression at baseline, lower CSF IL-6 levels predicted depression at one or more follow-up examination (p<0.03). Results from the generalized linear mixed logistic model using all baseline and follow-up data on depression status and Mini Mental State Examination score showed a significant relationship between IL-6 and depression (p=0.005 OR 0.370 CI [0.184-0.744]). CONCLUSION: Lower levels of CSF IL-6 were associated with current depression and with future depression during a follow-up of almost two decades. Our findings suggest that lower levels of CSF IL-6 may be related to depression vulnerability in later life.

Differences in lesion severity and cellular composition between in vivo assessed upstream and downstream sides of human symptomatic carotid atherosclerotic plaques.

BACKGROUND: The heterogeneous structure of carotid atherosclerotic plaques may be better understood if it is related to blood flow variations, influencing gene expression and cellular functions. Upstream of the maximum stenosis there is laminar blood flow and high shear stress, downstream there is turbulence and low shear stress. We studied if these variations were associated with differences in plaque morphology and composition between sites located up- and downstream of the maximum stenosis in symptomatic carotid plaques. METHODS: Patients with symptomatic carotid stenosis were examined with magnetic resonance angiography to localize the maximum stenosis in-vivo, prior to endarterectomy. In 41 endarterectomized specimens, transverse tissue sections prepared up- and downstream of the maximum stenosis were compared using histopathology and immunohistochemistry. RESULTS: The location of maximum stenosis relative the carotid bifurcation varied considerably between plaques. Compared with the downstream side, the upstream side of the stenosis had higher incidence of severe lesions with cap rupture and intraplaque hemorrhage, more macrophages, less smooth muscle cells and more collagen. CONCLUSIONS: The up- and downstream sides of symptomatic carotid plaques differed in plaque morphology and composition. This implies that the intraplaque location of sampling sites may be a confounding factor in studies of atherosclerotic plaques.

Biomarkers in the cerebrospinal fluid and neurodegeneration in Langerhans cell histiocytosis.

BACKGROUND: Progressive neurodegeneration may result in potentially severe cognitive and motor dysfunctions as a complication of Langerhans cell histiocytosis (LCH), a suggested IL-17A-associated inflammatory condition. To detect this complication (CNS-LCH) early and to evaluate the potential efficacy of therapeutic interventions, biomarkers detecting and measuring ongoing neurodegeneration would be valuable. We evaluated cerebrospinal fluid (CSF) biomarkers of ongoing neurodegeneration in CNS-LCH patients. PROCEDURE: Nine patients with endocrine, neuromotor, cognitive or/and behavioral abnormalities as well as neuroradiological evidence of CNS-LCH were evaluated 4-12 years after LCH diagnosis for CSF levels of neurofilament protein light chain (NF-L), glial fibrillary acid protein (GFAp), and total tau protein (TAU). Two patients were analyzed longitudinally. One hundred ten children with newly diagnosed acute lymphoblastic leukemia (ALL) served as controls. RESULTS: NF-L, TAU, and GFAp levels were elevated in four, six, and eight of nine patients studied, respectively. NF-L (P < 0.001) and GFAp (P < 0.001) were higher in patients than in controls (TAU not analyzed in controls). The patient with most severe clinical and neuroradiological CNS-LCH displayed the highest levels of NF-L and GFAp whereas three patients without signs of systemic disease had low TAU levels and normal/slightly elevated NF-L. NF-L tended to be higher at radiological progression of neurodegeneration than at status quo (P = 0.07). Notably, we experienced frequent lumbar puncture complications in these patients. CONCLUSIONS: CSF levels of NF-L, TAU, and GFAp appear to be elevated in CNS-LCH. It would be valuable if these markers were validated in order to serve as markers for early CNS-LCH, to monitor disease progression and to evaluate various treatment attempts for CNS-LCH.

Cerebrovascular complications in patients with left-sided infective endocarditis are common: a prospective study using magnetic resonance imaging and neurochemical brain damage markers.

Background. @nbsp; Cerebrovascular complications (CVCs) have remained a major therapeutic and prognostic challenge associated with infective endocarditis, and definite risk factors have not been fully elucidated. This prospective study was designed to the evaluate the total incidence of CVC associated with infective endocarditis and major risk factors. Methods. @nbsp; During 2 study periods, from June 1998 through April 2001 and from September 2002 through January 2005, patients were prospectively enrolled in the study regardless of neurological symptoms. Study patients underwent neurological examinations and magnetic resonance imaging of the brain, and cerebrospinal fluid analyses of inflammatory and neurochemical markers of brain damage (neurofilament protein and glial fibrillary acidic protein) were performed. Results. @nbsp; Sixty patients who experienced episodes of left-sided infective endocarditis were evaluated; 35% of these patients experienced a symptomatic CVC. Silent cerebral complications were detected in another 30% of the patients, and the total CVC rate was 65% (95% confidence interval, 58%-72%). Five percent of patients experienced their first neurological symptom after the initiation of antibiotic treatment without prior surgery. No new symptomatic CVCs were detected after 10 days of antibiotic treatment. No neurological deterioration was observed after surgery in patients who were established to have a symptomatic CVC preoperatively. A larger heart valvular vegetation size was a risk factor for both symptomatic and silent CVCs; Staphylococcus aureus etiology conferred a higher risk for symptomatic cerebral complication only. Conclusions. @nbsp; The use of sensitive methods of detection indicates that the incidence of CVC associated with infective endocarditis is high, but the risk for neurological deterioration during cardiac surgery after a CVC is lower than previously assumed. The major mechanism behind cerebral complications associated with infective endocarditis is cerebral embolization, although the dominant neurological symptoms vary considerably.

Neurochemical markers of brain damage in cerebrospinal fluid during induction treatment of acute lymphoblastic leukemia in children.

BACKGROUND: Central nervous system (CNS) irradiation has been replaced by systemic high-dose methotrexate (MTX) and intrathecal MTX in acute lymphoblastic leukemia treatment due to the risk of late effects. However, treatment without CNS irradiation might also cause brain damage. PROCEDURE: Cerebrospinal fluid (CSF) was analyzed in 121 patients in an attempt to detect CNS injury. Seventy-three samples were analyzed for neuron-specific enolase (NSE), 108 for glial fibrillary acidic protein (GFAp), 110 for neurofilament protein light chain (NFp), and 70 for ascorbyl radical (AsR). Samples were taken at day 0, 8, 15, and 29 during induction treatment, including intrathecal MTX. Levels at days 8, 15, and 29 were compared with the levels before treatment. RESULTS: NSE levels were 9.0 (+/-3.5) microg/L (mean (+/-SD)) at day 0, 15.0 (+/-5.3) at day 8 (P < 0.001), 13.6 (+/-4.7) at day 15 (P < 0.001) and 11.1 (+/-4.3) at day 29 (P < 0.001). GFAp were 177 (+/-98) ng/L at day 0, 206 (+/-101) at day 8 (P < 0.001), 200 (+/-106) at day 15 (n.s.) and 228 (+/-137) at day 29 (P < 0.001). NFp were below the detection limit 125 ng/L at day 0 in all 110 CSF samples analyzed, and increased significantly above the detection limit in 6/77 samples at day 8, in 11/84 at day 15 and in 22/91 at day 29. The AsR content did not change significantly. CONCLUSIONS: Levels of NSE, GFAp, and NFp increased in CSF, which can be interpreted as early signs of brain damage. AsR levels do not show any convincing signs of oxidative stress.

No neurochemical evidence for brain injury caused by heading in soccer.

BACKGROUND: The possible injurious effect to the brain of heading in soccer is a matter of discussion. OBJECTIVE: To determine whether standardised headings in soccer are associated with increased levels of biochemical markers for neuronal injury in cerebrospinal fluid (CSF) and serum. METHODS: 23 male amateur soccer players took part in a heading training session involving heading a ball kicked from a distance of 30 m at least 10 m forward. Ten players performed 10 and 13 players performed 20 approved headings. The players underwent lumbar puncture and serum sampling 7-10 days after the headings. The study also included 10 healthy male non-athletic control subjects. CSF was analysed for neurofilament light protein, total tau, glial fibrillary acidic protein, S-100B and albumin concentrations. Serum was analysed for S-100B and albumin. RESULTS: None of the biomarker levels were abnormal and there were no significant differences between any of the three groups, except for a slightly increased CSF S-100B concentration in controls compared with headers. Biomarker levels did not correlate with the number of headings performed. CONCLUSION: Repeated low-severity head impacts due to heading in soccer are not associated with any neurochemical signs of injury to the brain.

CSF neurofilament protein (NFL) -- a marker of active HIV-related neurodegeneration.

BACKGROUND AND METHODS: The light subunit of the neurofilament protein (NFL), a major structural component of myelinated axons, is a sensitive indicator of axonal injury in the central nervous system (CNS) in a variety of neurodegenerative disorders. Cerebrospinal fluid (CSF) NFL concentrations were measured by ELISA (normal < 250 ng/l) in archived samples from 210 HIV-infected patients not taking antiretroviral treatment: 55 with AIDS dementia complex (ADC), 44 with various CNS opportunistic infections/tumours (CNS OIs), 95 without neurological symptoms or signs, and 16 with primary HIV infection (PHI). The effect of highly active antiretroviral treatment (HAART) was studied by repeated CSF sampling in four of the ADC patients initiating treatment. RESULTS: CSF NFL concentrations were significantly higher in patients with ADC (median 2590 ng/l, IQR 780-7360) and CNS OIs (2315 ng/l, 985-7390 ng/l) than in neuroasymptomatic patients (<250 ng/l, <250-300) or PHI (<250 ng/l, <250-280), p < 0.001. Among patients with ADC, those with more severe disease (stage 2-4) had higher levels than those with milder disease (stage 0.5-1), p < 0.01. CSF NFL declined during HAART to the limit of detection in parallel with virological response and neurological improvement in ADC.CSF NFL concentrations were higher in neuroasymptomatic patients with lower CD4-cell strata than higher, p < 0.001. This increase was less marked than in the ADC patients and noted in 26/58 neuroasymptomatic patients with CD4 counts <200/microl compared to 1/37 with CD4-cells > or =200/microl. CONCLUSIONS: The findings of this study support the value of CSF NFL as a useful marker of ongoing CNS damage in HIV infection. Markedly elevated CSF NFL concentrations in patients without CNS OIs are associated with ADC, follow the grade of severity, and decrease after initiation of effective antiretroviral treatment. Nearly all previously suggested CSF markers of ADC relate to immune activation or HIV viral load that do not directly indicate brain injury. By contrast NFL is a sensitive marker of such injury, and should prove useful in evaluating the presence and activity of ongoing CNS injury in HIV infection.

Multilevel somatosensory evoked potentials and cerebrospinal proteins: indicators of spinal cord injury in thoracoabdominal aortic aneurysm surgery.

OBJECTIVE: Multilevel somatosensory evoked potentials (SSEP) and the release of biochemical markers in cerebrospinal fluid (CSF) were investigated to identify patients with spinal cord ischemia during thoracoabdominal aortic repair and/or a vulnerable spinal cord during the postoperative period. METHODS: Thirty-nine consecutive patients undergoing elective aneurysm repair using distal aortic perfusion and cerebrospinal fluid drainage were studied. Continuous SSEP were monitored using nerve stimulation of the right and left posterior tibial nerves with signal recording at the level of both common peroneal nerves, the cervical cord and at the cortical level. CSF concentrations of the markers glial fibrillary acidic protein (GFAp), the light subunit of neurofilament triplet protein (NFL), and S100B were determined at different time points from before surgery until 3 days postoperatively. RESULTS: SSEP indicated spinal cord ischemia in two patients leading to additional intercostal artery reattachments. In one of them the signal loss was permanent and the patient woke up with paraplegia. In the other the signal returned but the patient later developed delayed paraplegia. Three patients without SSEP indications of spinal cord ischemia during surgery later developed delayed paraplegia. The patients with spinal cord symptoms had significant increases, during the postoperative period of CSF biomarkers GFAp (571-fold), NFL (14-fold) and S100B (18-fold) compared to asymptomatic patients. GFAp increased before or in parallel to onset of symptoms in the patients with delayed paraplegia. CONCLUSIONS: Peroperative multilevel SSEP has a high specificity in detecting spinal cord ischemia but does not identify all patients with a postoperative vulnerable spinal cord. Biochemical markers in CSF increase too late for intraoperative monitoring but GFAp is promising for identifying patients at risk for postoperative delayed paraplegia.

Exposure of cultured astroglial and microglial brain cells to 900 MHz microwave radiation.

The rapid rise in the use of mobile communications has raised concerns about health issues related to low-level microwave radiation. The head and brain are usually the most exposed targets in mobile phone users. In the brain, two types of glial cells, the astroglial and the microglial cells, are interesting in the context of biological effects from microwave exposure. These cells are widely distributed in the brain and are directly involved in the response to brain damage as well as in the development of brain cancer. The aim of the present study was to investigate whether 900 MHz radiation could affect these two different glial cell types in culture by studying markers for damage-related processes in the cells. Primary cultures enriched in astroglial cells were exposed to 900 MHz microwave radiation in a temperature-controlled exposure system at specific absorption rates (SARs) of 3 W/kg GSM modulated wave (mw) for 4, 8 and 24 h or 27 W/kg continuous wave (cw) for 24 h, and the release into the extracellular medium of the two pro-inflammatory cytokines interleukin 6 (Il6) and tumor necrosis factor-alpha (Tnfa) was analyzed. In addition, levels of the astroglial cell-specific reactive marker glial fibrillary acidic protein (Gfap), whose expression dynamics is different from that of cytokines, were measured in astroglial cultures and in astroglial cell-conditioned cell culture medium at SARs of 27 and 54 W/kg (cw) for 4 or 24 h. No significant differences could be detected for any of the parameters studied at any time and for any of the radiation characteristics. Total protein levels remained constant during the experiments. Microglial cell cultures were exposed to 900 MHz radiation at an SAR of 3 W/kg (mw) for 8 h, and I16, Tnfa, total protein and the microglial reactivity marker ED-1 (a macrophage activation antigen) were measured. No significant differences were found. The morphology of the cultured astroglial cells and microglia was studied and appeared to be unaffected by microwave irradiation. Thus this study does not provide evidence for any effect of the microwave radiation used on damage-related factors in glial cells in culture.

Neuronal and astrocytic damage in systemic lupus erythematosus patients with central nervous system involvement.

OBJECTIVE: Symptoms originating from the central nervous system (CNS) frequently occur in patients with systemic lupus erythematosus (SLE). CNS involvement in lupus is associated with increased morbidity and mortality. Currently, reliable markers for activity in this condition are absent. The goal of this study was to determine the level of the light subunit of the neurofilament triplet protein (NFL) and that of glial fibrillary acidic protein (GFAP) in the cerebrospinal fluid of SLE patients with clinically verified CNS involvement and compare them with the levels in SLE patients without CNS involvement. METHODS: We assessed cerebrospinal fluid obtained from 99 patients with SLE and 99 age-matched controls for the presence of soluble molecules indicating neuronal destruction and astrogliosis-NFL and GFAP, respectively. Patients were evaluated clinically, with magnetic resonance imaging (MRI) of the brain, cerebrospinal fluid analyses, and neuropsychiatric tests. RESULTS: In the group of lupus patients with CNS involvement, intrathecal levels of NFL and GFAP were increased an average of 7-fold (P

Biochemical markers of cerebrospinal ischemia after repair of aneurysms of the descending and thoracoabdominal aorta.

OBJECTIVE: To investigate the clinical potential of several markers of spinal cord ischemia in cerebrospinal fluid (CSF) and serum during aneurysm repair of the descending thoracic or thoracoabdominal aorta. DESIGN: Observational study of consecutive patients. Nonblinded, nonrandomized. SETTING: University hospital thoracic surgical unit. PARTICIPANTS: Eleven consecutive elective patients. INTERVENTIONS: Distal extracorporeal circulation and maintenance of CSF pressure <10 mmHg until intrathecal catheter removal. MEASUREMENTS AND MAIN RESULTS: CSF and serum levels of S100B (and its isoforms S100A1B and S100BB), neuronal-specific enolase (NSE), and the CSF levels of glial fibrillary acidic protein (GFAp) and lactate were determined. Two patients had postoperative neurologic deficit. One with a stroke showed a 540-fold increased GFAp, a 6-fold NSE, and S100B increase in CSF. One with paraplegia had a 270-fold increase in GFAp, a 2-fold increase in NSE, and 5-fold increased S100B in CSF. One patient without deficit increased GFAp 10-fold, NSE 4-fold, and S100B 23-fold in CSF. CSF lactate increased >50% in 6 of 9 patients without neurologic deficit. Serum S100B increased within 1 hour of surgery in all patients without any concomitant increase in CSF. S100A1B was about 70% of total S100B in both serum and CSF in patients with or without neurologic defects. S100B in CSF increased 3-fold in 3 of 9 asymptomatic patients. CONCLUSIONS: In patients with neurologic deficit, GFAp in CSF showed the most pronounced increase. Biochemical markers in CSF may increase without neurologic symptoms. There is a significant increase in serum S100B from surgical trauma alone without any increase in CSF.

Regional oxygenation and systemic inflammatory response during cardiopulmonary bypass: influence of temperature and blood flow variations.

OBJECTIVE: To evaluate the role of target temperature (28 degrees or 34 degrees C) in cardiac surgery on regional oxygenation during hypothermia and rewarming and systemic inflammatory response. DESIGN: Prospective, controlled, and randomized clinical study. SETTING: University hospital. PARTICIPANTS: Elderly patients (mean age 70 +/- 2 years) with acquired heart disease with an anticipated bypass time exceeding 120 minutes (n = 30). INTERVENTIONS: The patients were cooled to either 28 degrees C (n = 15) or 34 degrees C (n = 15). At hypothermia, bypass blood flow was reduced twice from full flow (2.4 L/min/m(2) body surface area [BSA]) to 2.0 L/min/m(2). MEASUREMENTS AND MAIN RESULTS: Hepatic and jugular venous oxygen tension and saturation were higher at 28 degrees C than at 34 degrees C. In comparison with the preoperative values, at 28 degrees C hepatic venous values were higher; whereas at 34 degrees C, they were lower. The reduction of pump blood flow during hypothermia, from 2.4 to 2.0 L/min/m(2)was accompanied by reductions of central, jugular, and hepatic oxygenation at both target temperatures. During rewarming, central and regional venous oxygenation decreased irrespective of the preceding temperature. The decrease was most pronounced in hepatic venous blood, with the lowest individual values <10%. Serum concentrations of C3a and IL-6 increased during hypothermia and increased further during rewarming irrespective of the preceding temperature. CONCLUSION: During cardiopulmonary bypass, hypothermia at 28 degrees C increases regional and central venous oxygenation better than at 34 degrees C. In contrast, venous oxygenation decreases during rewarming irrespective of the preceding temperature. No significant difference in the systemic inflammatory response associated with target temperature was detected.

Monoclonal antibodies selective for low molecular weight neurofilaments.

Neurofilaments are necessary for the maintenance of axonal caliber and structural organization of nerve cells. The low molecular weight form of neurofilament, the neurofilament light protein, which serves as the core of the filament, was used as immunogen for generation of hybridomas with selective reactivity with this form of the filament. Six hybridomas, out of approximately 100 tested clones, were highly discriminatory. All involved epitopes were localized to the rod region of the antigen, as determined by alpha-chymotrypsin digestion of the purified filament and enzymatic peptide mapping. Synthetic peptides (20 mers) covering the entire rod region did not react with the antibodies. A phage display peptide library was used to identify four consensus sequences for the antibodies. The results indicate that all epitopes were of conformational type. Pair-wise BIAcore data furthermore indicated that the epitopes were independent. The access to such specific reagents is a prerequisite for further elucidation of the biology of the low molecular weight form of neurofilaments proteins.