Long-term treatment of generalised myasthenia gravis with FK506 (tacrolimus).

Efficacy and safety of long term use of FK506 (2-4.5 mg/day) for a maximum of two years were evaluated in 12 patients with generalised myasthenia gravis (MG). At the end of the study, eight patients (67%) showed improvement in either MG score or Activities in Daily Living score, and prednisolone dosage could be reduced in seven patients (58%), with a mean reduction ratio of 37%. Long term use of FK506 for MG can be more effective than short term administration, with no serious side effects.

Attenuated neurodegenerative disease phenotype in tau transgenic mouse lacking neurofilaments.

Previous studies have shown that transgenic (Tg) mice overexpressing human tau protein develop filamentous tau aggregates in the CNS. The most abundant tau aggregates are found in spinal cord and brainstem in which they colocalize with neurofilaments (NFs) as spheroids in axons. To elucidate the role of NF subunit proteins in tau aggregate formation and to test the hypothesis that NFs are pathological chaperones in the formation of intraneuronal tau inclusions, we crossbred previously described tau (T44) Tg mice overexpressing the smallest human tau isoform with knock-out mice devoid of NFL (NFL-/-) or NFH (NFH-/-). Depletion of NF subunit proteins from the T44 mice (i.e., T44;NFL-/- and T44;NFH-/-), in particular NFL, resulted in a dramatic decrease in the total number of tau-positive spheroids in spinal cord and brainstem. Concomitant with the reduction in spheroid number, the bigenic mice showed delayed accumulation of insoluble tau protein in the CNS, increased viability, reduced weight loss, and improved behavioral phenotype when compared with the single T44 Tg mice. These results imply that NFs are pathological chaperones in the development of tau spheroids and suggest a role for NFs in the pathogenesis of neurofibrillary tau lesions in neurodegenerative disorders that contain both NFs and tau proteins.

Enhanced expression of I-kappaB with neurofibrillary pathology in Alzheimer's disease.

Inflammatory and immune responses are known to be involved in the pathogenesis of Alzheimer's disease (AD). NF-kappaB is a major transcription factor that plays a central role in the inflammatory and immune responses and is regulated by I-kappaB through an autoregulatory feedback system. Southwestern immunohistochemistry and immunohistochemistry in our study demonstrated activated NF-kappaB in AD brains. However, there was also activated expression of I-kappaB in a distribution that corresponded to the neurofibrillary pathology of AD. These observations indicate that disruption of the autoregulatory mechanism of NF-kappaB in brain regions with neurofibrillary pathology may play a role in the pathogenesis of AD.

Expression of matrix metalloproteinase-9 and urinary-type plasminogen activator in Alzheimer's disease brain.

OBJECTIVE: Urinary-type plasminogen activator (uPA) binding to uPA receptor (uPAR) promotes the activation of matrix metalloproteinase-9 (MMP-9), which degrades amyloid beta protein (Abeta) in vitro. We investigated the expression of MMP-9, uPA, and uPAR in post-mortem brains from patients with Alzheimer's disease (AD) and those with vascular dementia (VD). MATERIAL AND METHODS: We used immunohistochemistry to examine the sections of the parietal lobe and hippocampus from 4 AD and 3 VD patients. The anti-MMP-9 antibody, anti-uPA antibody, and anti-uPAR antibody were used to perform immunohistological analysis. RESULTS: In the brain tissues from the AD patients, we found expression of MMP-9 in the cytoplasm of neurons, neurofibrillary tangles, senile plaques, vascular walls and uPAR expression in the cytoplasm of neurons and vascular walls. uPA was detected only in the vascular walls. On the other hand, we could not find expression of MMP-9, uPAR and uPA in the brain tissues of the VD patients, except for the vascular walls. CONCLUSION: The neurons in the AD brains expressed MMP-9 and uPAR. MMP-9 may be produced for the degradation of Abeta, but uPA, which activates MMP-9, was not immunolocalized to the neurons in the AD brains.

Influence of the light schedule on the toxic interaction between propranolol and disopyramide in chick embryos.

The effect of the light schedule on toxic interactions between propranolol and disopyramide were studied in chick embryos. Fertilized eggs of White Leghorns were incubated under dark conditions and investigated, on two occasions, under light conditions or under dark conditions. Propranolol, with and without disopyramide, was injected into the air sac of fertilized eggs on the 16th day of incubation. Electrocardiograms (ECGs) were recorded 0 to 60 min after the injection. After the injection of propranolol with disopyramide, the heart rate was significantly decreased compared with the injection of propranolol alone under light conditions. In addition, this toxic interaction between propranolol and disopyramide was more severe under dark conditions than under light conditions. These findings indicate that manipulation of the light schedule has a marked influence on the toxic interaction between propranolol and disopyramide in chick embryos.

Serum levels of tumor necrosis factor-alpha in chronic inflammatory demyelinating polyneuropathy.

BACKGROUND: Activated macrophages and T lymphocytes may play a role in the pathogenesis of chronic inflammatory demyelinating polyneuropathy (CIDP). Both cell types secrete tumor necrosis factor-alpha (TNFalpha), which has toxic effects on myelin and endothelial cells. METHODS: The serum concentration of TNFalpha was measured by ELISA and compared with clinical and electrophysiological profiles in 20 patients with CIDP. RESULTS: An increased serum level of TNFalpha was detected in 5 (25%) patients and was associated with subacute progression, severe neurologic disabilities, and symmetric weakness involving proximal as well as distal muscles. TNFalpha levels increased during the active phase in this subgroup of patients. The levels of TNFalpha correlated with the severity of demyelinating conduction abnormalities in the intermediate as well as distal nerve segments, suggesting demyelination diffusely distributed along the nerves. CONCLUSION: Circulating TNFalpha increases during the active phase in a subgroup of CIDP patients and may play a role in the pathogenesis of demyelination and the breakdown of the blood-nerve barrier in CIDP.

Age-dependent induction of congophilic neurofibrillary tau inclusions in tau transgenic mice.

Intraneuronal filamentous tau inclusions such as neurofibrillary tangles (NFTs) are neuropathological hallmarks of Alzheimer's disease (AD) and related sporadic and familial tauopathies. NFTs identical to those found in AD brains have also been detected in the hippocampus and entorhinal cortex of cognitively normal individuals as they age. To recapitulate age-induced NFT formation in a mouse model, we examined 12- to 24-month-old transgenic (Tg) mice overexpressing the smallest human brain tau isoform. These Tg mice develop congophilic tau inclusions in several brain regions including the hippocampus, amygdala, and entorhinal cortex. NFT-like inclusions were first detected in Tg mice at 18 to 20 months of age and they were detected by histochemical dyes that bind specifically to crossed beta-pleated sheet structures (eg, Congo red, Thioflavin S). Moreover, ultrastructurally these lesions contained straight tau filaments comprised of both mouse and human tau proteins but not other cytoskeletal proteins (eg, neurofilaments, microtubules). Isolated tau filaments were also recovered from detergent-insoluble tau fractions and insoluble tau proteins accumulated in brain in an age-dependent manner. Thus, overexpression of the smallest human brain tau isoform resulted in late onset and age-dependent formation of congophilic tau inclusions with properties similar to those in the tangles of human tauopathies, thereby implicating aging in the pathogenesis of fibrous tau inclusions.

Frontotemporal dementia and tauopathy.

The presence of abundant neurofibrillary lesions made of hyperphosphorylated tau proteins is the characteristic neuropathology of a subset of neurodegenerative disorders classified as "tauopathies." The discovery of mutations in the tau gene in frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) constitutes convincing evidence that tau proteins play a key role in the pathogenesis of neurodegenerative disorders. Moreover, it now is known that the most common form of sporadic frontotemporal dementia (FTD), which is characterized by frontotemporal neuron loss, gliosis, and microvacuolar change, also is a tauopathy caused by a loss of tau protein expression. Thus, these discoveries have begun to change the classification and the neuropathologic diagnosis of FTD and tauopathies, as well as current understanding of the disease mechanisms underlying them. Although transgenic mice expressing wild-type human tau or variants thereof with an FTDP-17 mutation result in tau pathologies and brain degeneration similar to that seen in human tauopathies, the precise mechanisms leading to the onset and progression of neurodegenerative disorders remain incompletely understood. Here, we review current understanding of human neurodegenerative tauopathies and prospects for translative recent insights about these into therapeutic interventions to prevent or ameliorate them.

The effect of fosfomycin on glycopeptide antibiotic-induced nephrotoxicity in rats.

The effect of coadministration of fosfomycin (FOM) on glycopeptide antibiotic-induced nephrotoxicity for 3 days was investigated in rats. To induce nephrotoxicity in a short time, gentamicin (GM) was also coadministered. In the present study, FOM decreased glycopeptide antibiotic-induced nephrotoxicity as shown by reduced urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) as well as fewer histopathological signs of nephrotoxicity in the groups treated with the combination of glycopeptide and FOM as compared with a glycopeptide alone. In addition, the higher the dose of FOM, the more it decreased urinary NAG levels, suggesting that the role of FOM in alleviating nephrotoxicity is dose dependent. The accumulation of teicoplanin and vancomycin was significantly lower in the renal cortex of rats treated with the combination of glycopeptide antibiotics and FOM as compared with glycopeptide antibiotics alone (P < 0.05). In conclusion, the concomitant administration of FOM and glycopeptide antibiotics may help to achieve a chemotherapeutic strategy that reduces the nephrotoxic effects of glycopeptide antibiotics.

[Beneficial effects of CHOP therapy in a case of intravascular large B-cell lymphoma diagnosed by skin biopsy].

We report a case of intravascular large B-cell lymphoma. A 52-year-old man gradually developed dementia and abnormal behaviors, which were later accompanied by spastic paraplegia and sensory disturbance in his lower limbs. MR imaging of his brain showed high signal intensity lesions on T2 imaging. IMP-SPECT images of the brain showed diffuse reduction of radioisotope uptake. Many skin rashes that looked like senile hemangioma were observed on his body. Several of those were biopsied, and the diagnosis of intravascular large B-cell lymphoma was made because of malignant B lymphocytes filling the vessel lumens in one of the seven biopsy specimens. CHOP therapy was performed and found to be effective for the neurological disorders such as dementia, paraplegia, and sensory disturbance. Our case suggests that skin biopsy for more than one sample of the skin rashes is very important for the diagnosis of intravascular large B-cell lymphoma. CHOP therapy might be effective in this case because of early diagnosis by skin biopsy.

Expression of invariant chain and pro-cathepsin L in Alzheimer's brain.

Inflammatory and immune systems are involved in the pathogenesis of Alzheimer's disease (AD), but those systems in the human brain have not been well identified. Cathepsin L might play a predominant role in the degradation of the invariant chain (Ii), which plays a critical role in antigen presentation to block the antigen-binding site of the major histocompatibility complex class II. We examined the expression of Ii and pro-cathepsin L (pCPL) in AD and normal brains by using immunohistochemistry. Ii expresses only in resting or mildly activated microglia, whereas pCPL strongly expresses in fully activated microglia but not in resting or mildly activated microglia in AD. Normal brain tissues have rarely been stained for Ii or pCPL. These results suggest that the activation of microglia leads to expression of a complex of Ii and human leukocyte antigen class II at first, and that further activation, which is followed by cluster formation and enlargement of microglia frequently seen in the AD brain, might cause pCPL expression to degrade Ii. Our study confirmed that microglia plays a central role in the immune system of the brain, and that an activation of microglia is involved in the pathogenesis of AD.

Selective distribution of matrix metalloproteinase-3 (MMP-3) in Alzheimer's disease brain.

A growing amount of evidence indicates that matrix metalloproteinases (MMPs) may play an important role in the pathogenesis of Alzheimer's disease (AD). Stromelysin-1 (MMP-3) plays a central role in activating latent-type MMPs, which are originally secreted as proenzymes. We examined MMP-3 immunoreactivity in the brains of patients who had suffered from Alzheimer's disease and in those of neurologically normal persons. The interstitium between myelinated axons and astrocytes in the white matter of all brain tissues, and senile plaques in the gray matter of the patients with AD were stained with a monoclonal antibody to MMP-3. Comparison of the number of senile plaques stained with the antibody against MMP-3 in the parietal cortex with that in the hippocampus showed that fewer plaques were stained in the hippocampus. The selective distribution of MMP-3 in the human brain suggests that MMP-3 might play an important role in the pathogenesis of AD, especially in the degradation of beta-amyloid protein.

Nephrotoxicity of teicoplanin in rats.

Teicoplanin, a glycopeptide antibiotic, is marketed in a number of European countries and has recently been put on the market in Japan. The spectrum of antibacterial activity of teicoplanin is equivalent or superior to that of vancomycin. The aim of the present study is to examine the nephrotoxicity of teicoplanin compared with vancomycin in rats. Wistar male rats, housed in a light-controlled room at room temperature for 1 week, were used. They were injected with either 15 or 50 mg/kg/day of teicoplanin or 50 or 200 mg/kg/day of vancomycin at 13:00 daily for 14 days. The rats were randomly assigned to groups of five rats each and were housed individually in metabolic cages to collect urine. Urine samples were collected 24 hours prior to the drug treatment and every 24 hours thereafter for 14 days. N-Acetyl-beta-D-glucosaminidase (NAG) activity was determined in the supernatant and expressed in international units per total urine collected for 24 hours. The group which was given vancomycin 200 mg/kg/day had significantly elevated urinary NAG levels compared with the other groups (p < 0.05). No significant differences were observed in the NAG levels in urine among the remaining three groups. These results suggest that the nephrotoxicity of teicoplanin may be only one-fourth that of vancomycin in rats. It appears that by extrapolating the dose amount required for the treatment in humans to rats, the high dose of teicoplanin was set at 50 mg/kg/day and that of vancomycin, 200 mg/kg/day. The recommended dose for teicoplanin will probably be 200 mg/day compared to 2 g/day of vancomycin. If the teicoplanin dose is only one-tenth that of the vancomycin dose, then teicoplanin should be better tolerated than vancomycin in terms of nephrotoxicity.

The dropped head sign in parkinsonism.

We describe seven patients who exhibited the dropped head sign in parkinsonism. These included six females and one male between the ages of 53 and 74. Three patients were clinically diagnosed as probable Parkinson's disease and four were diagnosed with probable multiple system atrophy. None had weakness in the posterior neck muscles or spasms in the anterior neck muscles. When the patients attempted to extend the head voluntarily or passively muscle contraction that was not seen in the dropped-head condition appeared. Surface electromyography of the neck indicated that the anterior neck muscles had rigidity. A gamma-block of the SCM muscles reduced the muscle activity when the head was elevated and improved the dropped-head condition slightly. These findings seem to indicate that the dropped head sign in parkinsonism could be associated with anterior neck muscle rigidity. Although the severity of the dropped head condition was affected by medication or by the clinical course in three patients, there was no clear relationship between the severity of the dropped head condition and the parkinsonism. We suspected that unbalanced muscle rigidity between the anterior and the posterior neck muscles could cause the dropped head sign.

Expression of the membrane-type 3 matrix metalloproteinase (MT3-MMP) in human brain tissues.

Membrane-type 3 matrix metalloproteinase (MT3-MMP) is a novel MT-MMP which has a transmembrane domain at the C terminus, and mediates activation of pro-gelatinase A, just as does MT1-MMP. Previously, we reported that MT1-MMP was expressed on microglial cells only in the white matter [Yamada T, Yoshiyama Y, Sato H, Seiki M, Shinagawa A, Takahashi M (1995) Acta Neuropathol 90:421-424]. In the present study of both non-neurological and Alzheimer brain tissues, we examined the localization of MT3-MMP by immunohistochemistry. Anti-MT3-MMP antibodies gave positive staining of microglial cells in all brain tissues. Positively stained microglia were found not only in the white matter but also in the gray matter. Reverse transcriptase-polymerase chain reaction for MT3-MMP mRNA showed the same amount of expression in gray and white matters, while that for gelatinase A and MT1-MMP mRNA expressed much higher in the white matter than in the gray matter. These results suggest that MT3-MMP may play a role on microglial cells, although its role may be different from MT1-MMP in the brain.

Expression of adult T cell leukemia-derived factor in human brain and peripheral nerve tissues.

In both nonneurological and Alzheimer brains, we examined the localization of adult T cell leukemia-derived factor (ADF) by immunohistochemistry, that of its mRNA by in situ hybridization, and its semiquantitative mRNA analyses by RT-PCR. Anti-ADF antibody gave positive staining of white matter astrocytes and Schwann cells in the posterior root. Their intense and abundant staining was seen in Alzheimer brains. In situ hybridization for ADF mRNA showed identical signals in the white matter astrocytes. The evidence was also confirmed by RT-PCR analysis. These results suggest that redox regulation may play a role in Alzheimer pathology.

Protective effect of ceftriaxone against the nephrotoxicity of isepamicin administered once daily in rats.

The protective effect of ceftriaxone on isepamicin-induced nephrotoxicity was investigated. For 14 d, Wistar rats were administered either ceftriaxone 100 mg/kg intraperitoneally, isepamicin 300 mg/kg subcutaneously, or ceftriaxone isepamicin in combination. The animals given 300 mg/kg of isepamicin showed a significant increase in urine NAG (N-acetyl-beta-D-glucosaminidase) levels as compared with the control animals which received saline (p<0.01). However, the increase in NAG level was markedly less when isepamicin was administered in combination with ceftriaxone (p<0.01). Ceftriaxone alone had no effect on urine NAG activity. Serum creatinine levels were significantly higher in animals treated with isepamicin alone than in control animals (p<0.01) or animals receiving the isepamicin ceftriaxone combination (p<0.01). After 14 d of treatment, ceftriaxone had not accumulated in renal tissue, but it did reduce the renal intracortical accumulation of isepamicin (p<0.01). Histopathologically, ceftriaxone induced very few cellular alterations and considerably reduced the manifestation of typical signs of isepamicin nephrotoxicity. This investigation demonstrates that ceftriaxone protects animals against isepamicin-induced nephrotoxicity.

Possible roles of transglutaminases in Alzheimer's disease.

The localizations of two transglutaminases [factor XIIIa and tissue transglutaminase (tTG)] and their mRNAs were examined in human brain tissues from neurologically normal and Alzheimer disease (AD) cases, using immunohistochemical and in situ hybridization methods. In all cases, meningeal macrophages and ependymal macrophage/microglia were positive for factor XIIIa. The mRNA encoding factor XIIIa was detected in macrophages and microglia. As reported previously, intense staining with the antibody to factor XIIIa of a subset of microglia was seen in the parietal cortex in AD brains. Few or no microglia were found associated with classical senile plaques. In contrast, many labeled microglia were associated with primitive plaques. Further-more, most of these cells were mainly seen in the subpial cortical layer but were very rare in the hippocampus. On the other hand, few factor-XIIIa-positive microglia were found in the parietal cortices from non-neurological cases, but moderate numbers were found in their hippocampal tissues. TG and its mRNA were localized in astrocytes in all the cases. In AD, a few neurofibrillary tangles were positive to tTG. These results suggest that the subsets of microglia which express factor XIIIa may play some roles in the early phase of AD pathology.

[Distribution of amyloid precursor protein mRNA in Alzheimer brain tissues].

This study aimed to provide clear data on the localization of the mRNA for the amyloid precursor protein (APP) in human brain. It is known to occur in neurons but the possible localization in other type of brain cells is controversial among several authors. A cDNA probe constructed by polymerase chain reaction for APP, which was not specific for a particular isoform, gave punctate staining and showed a clear localization not only in neurons but in astrocytes in all brains, as well as in the reactive microglia associated with senile plaques in Alzheimer disease. A cRNA probe gave more diffuse staining of neurons and glia.