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At least 793 records · Page 44Linked to original sources
PubMed1997

Amyloid P immunoreactivity precedes C4d deposition on extracellular neurofibrillary tangles.

Extracellular neurofibrillary tangles (eNFTs) are the insoluble cytoskeletal debris left behind when neurons with intracellular neurofibrillary tangles (iNFTs) die. Reactive microglia and reactive astrocytes gather around eNFTs. Many inflammatory proteins are deposited in their vicinity, including activated components of the classical complement pathway. Agents which are potential activators of the pathway include beta-amyloid protein (A beta) and amyloid P (AP), since these in vitro activators have been reported to be associated with both senile plaques (SPs) and eNFTs. To investigate the apparent order in which these proteins are deposited, we studied by immunohistochemistry the relative association of AP, A beta, and the classical complement protein C4d with eNFTs in Alzheimer's disease (AD), parkinsonism-dementia complex of Guam (lytico-bodig, LB), and elderly non-demented cases. In normal elderly cases with mild tangle development, most but not all eNFTs were AP positive. Substantially fewer eNFTs were C4d positive, and in two of the three cases no eNFTs were A beta positive. In AD and mild LB cases with more extensive tangle development, a high portion of eNFTs were AP positive, and most of them were C4d positive. Only a few were A beta positive. In severe LB cases, with dense tangle development, almost all eNFTs were AP and C4d positive, and a significant number were also A beta positive. AP seems to be deposited early in eNFT exposure and could therefore be a potential activator of the complement pathway, while A beta deposition occurs relatively late in the process, and is therefore unlikely to be responsible.

Aged↗
PubMed2006

A missense mutation in factor I (IF) predisposes to atypical haemolytic uraemic syndrome.

A genetic predisposition involving complement regulatory genes has become evident in some patients with atypical HUS. In this paper, a patient with a heterozygous missense mutation in factor I (IF) is described. Although the serum level of IF was normal, a mild functional defect in the alternative pathway of complement could be demonstrated in the affected members of the family. After an episode of atypical HUS, chronic renal insufficiency started at the age of 15 months. Recurrence of HUS, with loss of the renal transplant, occurred twice in this patient. The recurrence of HUS in the graft was not reflected by haematological abnormalities (haemolysis, thrombocytopenia). One additional transplant was lost due to arterial thrombosis of the renal artery. This report confirms the gloomy outcome of renal transplants in patients with an IF deficiency. New therapies should be evaluated in these patients.

Complement C3↗
PubMed2006

Leukoencephalopathy as a rare complication of hepatitis C infection.

We report the case of a 64-year-old female patient with hepatitis C infection (HCV), who developed Sjögren's disease and sensory peripheral neuropathy. Clinical conditions worsened over three years with central nervous system involvement characterised by transient third cranial nerve paresis and mild selective impairment of attention and memory. Brain magnetic resonance imaging showed diffuse periventricular and lobar white matter hyperintensity. Laboratory findings included mixed cryoglobulinaemia (type II), cryocrit 1.47%, low serum levels of complement C4 and high levels of rheumatoid factor, HCV 1b genotype, high HCV mRNA levels in serum and cerebrospinal fluid. Skin biopsy showed evidence of vasculitis. After one year of plasmapheresis, immunosuppressant therapy and occasional corticosteroid treatment, neurological symptoms improved, skin biopsy changed and inflammation parameters normalised, suggesting that neurological symptoms might be related to the high levels of mixed cryoglobulins.

Female↗
PubMed1975

Serial complement studies in a patient with Goodpasture's syndrome treated with bilateral nephrectomy and renal transplantation.

A young male patient with Goodpasture's syndrome was treated with bilateral nephrectomy and when antiglomerular basement membrane antibodies could no longer be detected he received a cadaveric renal homograft. Fifteen months later he is in good health and without signs of pulmonary disease. Renal function is satisfactory, and there are no findings indicating recurrence of the nephritis. Serial complement studies during the entire course revealed varying degrees of activity in the sequence in the different phases: a high degree of in vivo activation of complement was found in the period before the nephrectomy, there was a moderate degree of activation in the period between the nephrectomy and transplantation and, finally, there were no signs of activity in the system after transplantation. This investigation strongly suggests that the complement system is of definite pathogenetic significance in this human equivalent to experimental nephrotoxic nephritis.

Adult↗
PubMed1979

Prophylaxis of attacks of hereditary angioedema.

Danazol, an attentuated androgen, has been suggested as an effective agent for the prophylaxis of attacks of hereditary angioedema. Four patients, with a clinical history of hereditary angioedema and a demonstrated depression of the serum inhibitor of the first component of complement (C1 INH) and the fourth component of complement (C4), were entered into a study to determine the minimum effective dose of this agent. All four of the patients had been experiencing attacks at least monthly, but they had only six attacks during a total of 60 patient months of Danazol therapy. The minimum effective dose varied from 100 to 400 mg/day. The drug appeared to work by increasing the level of serum C1 INH which reached the normal range in two of four patients. Side effects were only the anticipated menstrual irregularities in the female patients. Danazol appears to be an efficacious drug for prophylaxis of hereditary angioedema.

Adult↗
PubMed1989

Elevated plasma levels of the anaphylatoxins C3a and C4a are associated with a fatal outcome in sepsis.

PURPOSE AND PATIENTS AND METHODS: Both complement and contact system of coagulation have been implicated in the pathophysiology of sepsis. We therefore measured levels of the complement activation products C1-C1-inhibitor complexes and C3a in serial plasma samples (obtained every six hours) from 48 patients with clinically suspected sepsis, and related these levels to the clinical outcome. C4a was also measured in samples obtained on admission. RESULTS: C3a levels were elevated in 47 patients at least once during the observation period. These levels appeared to be considerably higher in patients who died than in patients who survived. This difference was found for the levels on admission (p = 0.0003), as well as for the highest (p = 0.0010) and the lowest (p less than 0.0001) levels encountered in each patient. The mortality in patients with plasma C3a levels of 13 nmol/liter or less on admission (27 patients) was 33 percent, compared with 86 percent in patients with levels of 14 nmol/liter or more. Patients with septic shock had significantly higher C3a levels than normotensive patients (p values between 0.046 and 0.004). No significant differences in C3a were found between patients who had respiratory distress syndrome and those who did not. C4a levels in plasma samples obtained on admission were elevated in 43 patients. These levels correlated very significantly with C3a levels (p less than 0.0001), and showed similar associations with a fatal outcome. C1-C1-inhibitor complexes were elevated in 23 patients at least once during the observation period. These patients had significantly higher levels of C4a and C3a than patients with normal amounts of C1-C1-inhibitor complexes. Patients who died had higher levels of C1-C1-inhibitor complexes than patients who survived. However, this difference was not significant. CONCLUSION: On the basis of our results, we propose that activation of the complement system via the classical pathway is involved in the development of fatal complications in sepsis.

Adolescent↗
PubMed1993

Morphological diversities of CD44 positive astrocytes in the cerebral cortex of normal subjects and patients with Alzheimer's disease.

The localization of CD44 was investigated immunohistochemically in postmortem human brain tissue of control subjects and patients with Alzheimer's disease. CD44 is a multifunctional cell surface glycoprotein that serves as a receptor for hyaluronic acid, collagen types I and VI, and mucosal vascular addressin. In gray matter, it was found to be associated with some astrocytes of both protoplasmic and fibrous morphology. These positively stained astrocytes were most frequently observed in association with blood vessels, and had morphologies that were highly comparable to those described with the Golgi technique. Double immunostaining for CD44 and glial fibrillary acidic protein (GFAP) revealed that a significant number of these astrocytes were positive for both antigens. However, GFAP staining was mostly confined to the cell somata and proximal processes, while CD44 staining extended to a rich and extensive array of processes. Occasional CD44 positive cells of spherical morphology with a few thin varicose processes were observed. Their processes formed thick terminations on blood vessels, suggesting that these cells are a special class of astrocyte. In Alzheimer's disease brain, the number of CD44 positive astrocytes increased dramatically. These data suggest that astrocytes have very extensive branching patterns, which are reflected by CD44 staining patterns. CD44 may be an important adhesion molecule for these astrocytic processes.

Adult↗
PubMed1984

Arachidonic acid-mediated and serum-opsonized-zymosan-mediated inhibition of complement production by macrophages. Lack of requirement for endogenous arachidonic acid metabolites.

The ability of exogenous prostaglandins to inhibit complement production (CP) by monocytes and macrophages (M phi) suggests that endogenous arachidonic acid metabolites produced by these cells may also regulate their rate of CP. We assessed the regulatory influence of endogenous metabolites on CP by M phi utilizing exogenous arachidonic acid and serum-opsonized zymosan as stimulators of production of cyclooxygenase and lipoxygenase metabolites. The results of this study show that (i) the inhibition of CP caused by both agents is is independent of arachidonic acid metabolites, suggesting that endogenously produced metabolites do not influence CP, and (ii) arachidonic acid and serum-opsonized zymosan inhibit production by independent mechanisms.

Animals↗
PubMed1984

Primary sequence differences between Chido and Rodgers variants of tryptic C4d of the human complement system.

Human tryptic C4d of the Chido and Rodgers variant was fragmented by cyanogen bromide and trypsin. The fragments were characterized by amino acid analysis and sequence determination. Polymorphism between the two genetic variants was detected in 5 positions. Four were closely located (residues 141, 142, 145, 146), where Leu, Ser, Ile, His occurred in the Chido variant and Pro, Cys, Leu, Asp in the Rodgers variant, respectively. In position 94 Gly was found in Chido and Asp in Rodgers. Alignment of the fragments was performed and it is concluded that tryptic C4d of both variants contains 346 residues.

Amino Acid Sequence↗