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Biomedical subjects

A C Ludolph

Publications and source records attributed to A C Ludolph.

At least 55 records · Page 3Linked to original sources
PubMed2000

Adenosine receptor up-regulation: initiated upon preconditioning but not upheld.

Activation of adenosine receptors is part of the endogenous defense against cerebral hypoxia and ischemia. However, it is not known which adenosine receptor subtypes mediate hypoxic tolerance upon chemical preconditioning. Selective A3 receptor mRNA up-regulation to 135 +/- 34% (mean +/- s.d.; p<0.05) was observed 1 h after preconditioning with 3-nitropropionate while A1 receptor mRNA levels remained unchanged (94 +/- 23%; n.s.). After 24h A3 and A1 receptor mRNA expression were both at control level. Further treatment in vitro resulted in a selective A3 receptor mRNA reduction. We conclude that the early (onset within hours) but not the late (duration of days) neuroprotection upon chemical preconditioning is associated with a selective up-regulation of A3 receptor mRNA. Detection of A3 receptor mRNA is very sensitive to prolonged stress in vitro.

Animals↗
PubMed2000

Treatment of amyotrophic lateral sclerosis--what is the next step?

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease which was thought to be untreatable. However, recent evidence in both experimental animals and men indicates that antiglutamatergic strategies are the first to have an influence on its pathogenesis and slow down the disease process. Since the effect of drugs is still small, this progress cannot only be seen as a success of the present but must also be acknowledged as a basis for future developments. How will future studies be designed? They will have to take into account that the disease presumably has a long preclinical period and they will use a number of novel compounds and treatment strategies which have been shown to be effective in transgenic animal models. This also implies that we are likely to use a combination of therapies and we will try to treat patients early. The latter will be associated with the demand for a novel clinical attitude toward the diagnosis of the disease and the development of novel markers for both the preclinical period and the longitudinal course of the disease.

Amyotrophic Lateral Sclerosis↗
PubMed2000

Clinicopathological study of atypical motor neuron disease with vertical gaze palsy and ballism.

The case of a 38-year-old patient with rapidly progressing motor neuron disease, complicated by major dysfunction of the extrapyramidal system and of vertical gaze is described. Neuropathological examination revealed a degenerative process that severely affected the lower motor neurons, as well as the neurons of the pars compacta of the substantia nigra, the nucleus of Darkschewitsch, the nucleus interstitialis of Cajal, the colliculi superiores, and the pallidum. The long tracts were unaffected at all levels of the brain stem and spinal cord. There was no convincing evidence for the presence of a multiple system atrophy or progressive supranuclear palsy; the results rather revealed a pattern of vulnerability characteristic of a variant of motor neuron disease.

Adult↗
PubMed2000

The role of excitotoxicity in ALS--what is the evidence?

It is well accepted that excitotoxic mechanisms contribute to the pathogenesis of acute neuronal death in stroke, epilepsy, or brain trauma. It is less widely acknowledged that excitotoxic mechanisms play a role in the pathogenesis of chronic neurological disorders, in particular neurodegenerative diseases. However, evidence is accumulating that this mechanism is indeed part of the pathogenesis of late-onset neurodegenerative diseases. One of the clinical examples may be amyotrophic lateral sclerosis, a disease in which antiexcitotoxic strategies have neuroprotective effects in both, an established animal model and in man. In addition, there is accumulating neuropathological, pathobiochemical and pathophysiological evidence which indicates that excitotoxic mechanisms are part of the pathogenesis of the human disease and consequently part of the mechanisms explaining selective vulnerability ("pathoclisis") in the human motor system.

Amyotrophic Lateral Sclerosis↗
PubMed2000

Recessively inherited amyotrophic lateral sclerosis: a Germany family with the D90A CuZn-SOD mutation.

Mutations of the SOD1 gene encoding the free radical scavenging enzyme copper-zinc superoxide dismutase (CuZn-SOD) occur in patients with familial amyotrophic lateral sclerosis (ALS). Recent reports have shown homozygosity for a CuZn-SOD mutation in exon 4, the D90A (Asp90A1a) mutation. Other mutations described to date show an autosomal dominant pattern of inheritance. This is the first description of autosomal recessively inherited ALS in an out-bred population in central Europe. This study confirms the earlier described characteristic phenotype reported in D90A homozygous ALS patients in Scandinavia and supports the theory of the existence of a strong modifying factor in some cases of ALS associated with mutations in the CuZn-SOD gene.

Adult↗
PubMed2000

Protective effects of riluzole on dopamine neurons: involvement of oxidative stress and cellular energy metabolism.

Riluzole is neuroprotective in patients with amyotrophic lateral sclerosis and may also protect dopamine (DA) neurons in Parkinson's disease. We examined the neuroprotective potential of riluzole on DA neurons using primary rat mesencephalic cultures and human dopaminergic neuroblastoma SH-SY5Y cells. Riluzole (up to 10 microM:) alone affected neither the survival of DA neurons in primary cultures nor the growth of SH-SY5Y cells after up to 72 h. Riluzole (1-10 microM:) dose-dependently reduced DA cell loss caused by exposure to MPP(+) in both types of cultures. These protective effects were accompanied by a dose-dependent decrease of intracellular ATP depletion caused by MPP(+) (30-300 microM:) in SH-SY5Y cells without affecting intracellular net NADH content, suggesting a reduction of cellular ATP consumption rather than normalization of mitochondrial ATP production. Riluzole (1-10 microM:) also attenuated oxidative injury in both cell types induced by exposure to L-DOPA and 6-hydroxydopamine, respectively. Consistent with its antioxidative effects, riluzole reduced lipid peroxidation induced by Fe(3+) and L-DOPA in primary mesencephalic cultures. Riluzole (10 microM) did not alter high-affinity uptake of either DA or MPP(+). However, in the same cell systems, riluzole induced neuronal and glial cell death with concentrations higher than those needed for maximal protective effects (> or =100 microM:). These data demonstrate that riluzole has protective effects on DA neurons in vitro against neuronal injuries induced by (a) impairment of cellular energy metabolism and/or (b) oxidative stress. These results provide further impetus to explore the neuroprotective potential of riluzole in Parkinson's disease.

1-Methyl-4-phenylpyridinium↗
PubMed1999

Impaired tolerance to repetitive hypoxia in hippocampal slices of Cu,Zn superoxide dismutase transgenic mice.

Energy metabolism is impaired in the Cu,Zn superoxide dismutase transgenic mouse model of amyotrophic lateral sclerosis. The goal was to investigate tolerance against single and repetitive hypoxia in C57B6SJL-TgN(SOD1-G93A)1GUR mice (G93A mice). Posthypoxic recovery (15 min hypoxia, 45 min recovery) of population spike amplitude in hippocampal region CA1 was 38 +/- 29% (mean +/- SD) in controls and 67 +/- 41% (ns) in G93A mice at day 40. Upon in vivo pretreatment with 20 mg/kg 3-nitropropionate posthypoxic recovery increased to 82 +/- 32% (P < 0.01) in controls and decreased to 35 +/- 33% in G93A mice (P < 0.05 to pretreated controls). Results at day 80 and 110 were similar. We conclude that G93A mice show a long-lasting impairment to sustain repetitive hypoxic episodes whereas tolerance to a single hypoxic episode is comparable to controls.

Amyotrophic Lateral Sclerosis↗
PubMed1999

The RNA of the glutamate transporter EAAT2 is variably spliced in amyotrophic lateral sclerosis and normal individuals.

Impaired re-uptake of synaptic glutamate, and a reduced expression of the glutamate transporter EAAT2 have been found in the motor cortex of patients with amyotrophic lateral sclerosis (ALS). Two splice forms of the EAAT2 RNA resulting from retention of intronic sequences (EAAT2/Int) and deletion of one protein coding exon (EAAT2/C1) have been reported to account for the EAAT2 protein loss in ALS. In this study we investigated the presence of two known (EAAT2/C1; EAAT2/Int) and three novel (EAAT2/C2-4) EAAT2 RNA in motor cortex of 17 ALS cases and 11 controls. Reverse transcription and PCR were carried out to amplify the complementary DNA of the complete and variably spliced EAAT2 transcripts. Nested PCR was followed to generate amplicons specific for EAAT2/C1-4 and EAAT2/Int. EAAT2/Int was detected in 59% of ALS specimens as compared to 36% of controls showing a trend but no statistical significance of a more frequent expression in ALS (Type I error 24.6%). EAAT2/C1-4 were found to be equally expressed in ALS patients and controls. Our results indicate that the involvement of EAAT2 transcripts in ALS is unlikely to be primary, and more complex than previously recognized. Alterations of quantitative expression of distinct EAAT2 splice forms in ALS cannot be excluded from this study and remain to be investigated.

Aged↗
PubMed1999

Visualization of defective mitochondrial function in skeletal muscle fibers of patients with sporadic amyotrophic lateral sclerosis.

The mitochondrial function in skeletal muscle was investigated in skeletal muscle biopsies of 26 patients with sporadic amyotrophic lateral sclerosis (ALS) and compared with investigations of 28 age-matched control muscle samples and biopsies of 6 patients with spinal muscular atrophy (SMA) and two patients with Tay-Sachs disease. In comparison to the control, SMA and Tay-Sachs biopsies, we observed in the ALS samples a significant about two-fold lower activity of complex I of mitochondrial respiratory chain. To visualise the distribution of the mitochondrial defect in skeletal muscle fibers we applied confocal laser-scanning microscopy and video fluorescence microscopy of NAD(P)H and fluorescent flavoproteins. The redox change of mitochondrial NAD(P)H and flavoproteins on addition of mitochondrial substrates, ADP, or cyanide were determined by measurement of fluorescence intensities with dual-photon UV-excitation and single-photon blue excitation. In skeletal muscle fibers of ALS patients with abnormalities of mitochondrial DNA (multiple deletions, n=1, or lower mtDNA levels, n=14) we observed a heterogeneous distribution of the mitochondrial defects among individual fibers and even within single fibers. In some patients (n=3) a mitochondrial defect was also detectable in cultivated skin fibroblasts. These findings support the viewpoint that the observed impairment of mitochondrial function in muscle of certain ALS patients is caused by an intrinsic mitochondrial defect which may be of pathophysiological significance in the etiology of this neurodegenerative disease.

Adult↗
PubMed1999

Increase of cellular hypoxic tolerance by erythromycin and other antibiotics.

Antibiotics are used extensively, but in addition to their anti-infectious effects some inhibit cellular energy metabolism. We investigated hypoxic tolerance following in vivo pretreatment with erythromycin and kanamycin, or in vitro pretreatment with ampicillin. Recovery of the CA1 population spike amplitude in hippocampal slices upon 15 min hypoxia improved time-dependently following single i.p. in vivo pretreatment with erythromycin (maximum at 6 h: recovery 90+/-7% (mean s.d.) vs 30% in untreated controls; p<0.01). The hypoxia-induced increase in NADH was smaller in slices that recovered from hypoxia. We conclude that antibiotics increase cellular hypoxic tolerance to a varying extent. Use of antibiotics in experimental studies may, therefore, distort conclusions about hypoxic sensitivity and confounding mechanisms. In contrast, antibiotics may provide an effective strategy to induce chemical preconditioning in humans.

Ampicillin↗
PubMed1999

Proton magnetic resonance spectroscopy in Kennedy syndrome.

OBJECTIVE: To seek regional metabolite abnormalities in patients with Kennedy disease (KD) using proton magnetic resonance spectroscopy. DESIGN: Nine patients with KD showing the typical phenotype without clinical signs of upper motor neuron involvement were compared with 17 male, age-matched, healthy control subjects. Relative metabolite concentrations for N-acetyl (NA) groups, choline-containing groups (Cho), phosphocreatine (Cr), and lactate (Lac) were determined in the brainstem and the motor region. RESULTS: Pathologic Lac signals suggesting impaired energy metabolism were absent in patients and controls. In the brainstem area, patients with KD showed a significant reduction in the NA/Cho metabolite ratio (P = .01). In the motor region, NA/Cho (P = .04) and NA/Cr (P = .03) ratios were significantly reduced. The reduction of the NA/Cho ratio in the motor region mainly resulted from decreased metabolite ratios in 3 patients. Changes in metabolite ratios did not correlate with the number of trinucleotide cytosine-adenine-guanine repeats from leukocytes. Because of the relatively small sample size due to the rarity of KD, these results should be considered preliminary. CONCLUSIONS: Spectroscopic data fail to provide further evidence for altered energy metabolism in KD. Metabolite changes in the brainstem indicate a reduction of the neuronal marker NA or elevated Cho. These findings may reflect neuronal loss or gliosis consistent with the known pathologic features. In a subset of patients, altered metabolite ratios best explained by neuronal loss suggest subclinical involvement of the motor region. The extent of metabolite changes does not correlate with the trinucleotide repeat length.

Acetylation↗
PubMed1999

FTDP-17: an early-onset phenotype with parkinsonism and epileptic seizures caused by a novel mutation.

Recently, mutations in the tau gene on chromosome 17 were found causative for autosomal dominantly inherited frontotemporal dementia and parkinsonism (FTDP-17). We describe a family carrying a missense mutation at nucleotide 1137 C --> T, resulting in the amino acid substitution P301S. Methods of investigations include clinical, electrophysiological, and imaging techniques. This kindred presents with a novel phenotype characterized by an early onset of rapidly progressive frontotemporal dementia and parkinsonism in combination with epileptic seizures. We define the dopaminergic deficits as being predominantly presynaptic by the use of single-photon emission computed tomography with a dopamine transporter ligand. The association of this early-onset phenotype with P301S mutation is not entirely consistent with current criteria for the diagnosis of frontotemporal dementias and may encourage the search for tau mutations in diseases similar but not identical to FTDP-17. Also, the change from proline to serine suggests that this mutation might contribute to tau hyperphosphorylation.

Adult↗
PubMed1999

Antiglutamate therapy of ALS--which is the next step?

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease which was thought to be untreatable for a long time. However, recent evidence in men indicates that antiglutamatergic strategies are the first to have an influence on its pathogenesis and slow down the disease process. Since the effect of the drugs is still small, this progress cannot only be seen as a success of the present but most also be acknowledged as a starting point for the future. How will these future studies look like? They will have to take into account that ALS presumably has a long preclinical period and they will use a number of novel compounds and treatment strategies which have recently been shown to be effective in a transgenic animal model. This also implies that we are likely to use combination therapies and have to try to treat patients early. The latter will be necessarily connected with the demand for a novel clinical attitude to the diagnosis of the disease.

Amyotrophic Lateral Sclerosis↗
PubMed1999

[Spiroergometry in diagnosis of mitochondrial diseases].

Cardiopulmonary exercise testing (CPX) is a non-invasive method of recording quantitative data from gas exchange and ventilation for the evaluation of oxidative metabolism at rest and during exercise. Determination of oxygen uptake (VO2) and carbon dioxide output (VCO2) describes the activity of anaerobic vs aerobic metabolism. An incremental exercise test measuring gas exchange, ventilation and lactate release was performed in healthy volunteers and in patients suffering from mitochondrial disorders. At rest as well as during exercise patients with mitochondrial disorders differ from healthy subjects with regard to gas exchange and ventilation parameters. During exercise, the decreased oxygen utilization of skeletal muscle and early activation of anaerobic metabolism in these patients are mirrored by a reduced anaerobic threshold, reduced maximal oxygen uptake and reduced oxygen pulse. Our study shows that CPX is a sensitive and practical clinical screening method of investigating mitochondrial disorders.

Adolescent↗
PubMed1999

Impairment of callosal and corticospinal system function in adolescents with early-treated phenylketonuria: a transcranial magnetic stimulation study.

The transcranial activation and the conduction properties of corticospinal and callosal neurons were investigated in 12 early-treated adolescents (aged 17.3, SD 3.5 years; range 14-27 years) with phenylketonuria (PKU) by focal transcranial magnetic stimulation (fTMS) of the motor cortex. The patients had no functionally relevant motor disturbances in daily life or on clinical testing. Corticospinally mediated excitatory (response thresholds, amplitudes, central motor latencies) and inhibitory [duration of postexcitatory inhibition (PI)] effects of fTMS were investigated in contralateral hand muscles. Transcallosal inhibition (TI) (onset latency, duration, transcallosal latency) of tonic electromyographic (EMG) activity was tested in ipsilateral muscles. Peripheral motor latencies were determined for responses elicited by magnetic stimulation over cervical nerve roots. Ten normal subjects served as controls. Since in all PKU patients, central and peripheral motor latencies were normal, no neurophysiological indication of a demyelination of corticospinal or peripheral motor fibres was found. However, cortical thresholds of corticospinally mediated responses were increased (52.1, SD 11.6% versus 35.0, SD 7.4% of maximum stimulator output; P < 0.05; n = 24 hands) and their amplitudes reduced (2.9, SD 1.4 mV versus 6.1, SD 1.5 mV, P < 0.05). The duration of PI was shortened (132, SD 53 ms versus 178, SD 57 ms; P < 0.05). TI was absent in 37.5% of the investigated hands or tended to be weak. When TI was present, its onset latencies (38.0, SD 3.6 ms versus 34.7, SD 3.3 ms) and transcallosal latencies were prolonged (18.5, SD 3.8 ms versus 14.8, SD 3.2 ms), while its duration was normal. These abnormal excitatory and inhibitory effects of fTMS suggest a reduced susceptibility of cortical excitatory and inhibitory neuronal structures compatible with a loss of neurons or a rarefication of their dendrites.

Adolescent↗
PubMed1999

Problems and pitfalls in the diagnosis of ALS.

Although misdiagnosis of amyotrophic lateral sclerosis (ALS) is rare, it may be more difficult to make a diagnosis in some groups of patients than in others. If a patient presents in the later stages of the disease, only a small number of alternative diagnoses need to be considered. These include spinal muscular atrophies of adult onset, inclusion body myositis and motor neuropathies with conduction block. The latter group in particular may present a serious diagnostic problem, as several groups have recently reported patients suffering from lower motor neuron syndrome without detectable conduction block, who responded unexpectedly to treatment with immunoglobulins. As recent laboratory results suggest that a lengthy pre-clinical period may precede clinical ALS, there is increased pressure for clinicians to make an early diagnosis so that the maximum effect can be achieved from neuroprotective drugs. Thus, diseases such as distal motor amyotrophies, pressure palsies of motor branches of hand nerves, and cervical myelopathies, which can be differentiated mainly by their time-course, may be relevant in the differential diagnosis of ALS in some patients. During recent years, a few patients have been seen in our clinic who presented with pure motor deficits but later developed a more complex pattern of vulnerability suggestive of multisystem degeneration. The existence of patients with a disease that borders the spectrum of motor neuron diseases cannot be disputed. These patients include those carrying the Huntington mutation and those suffering from Guam and New Guinea disease ('ALS/PD'). From our experience, however, these 'difficult' diagnoses represent less than 10% of the patients seen in our clinic.

Adult↗
PubMed1999

HEK-293 cells expressing the human dopamine transporter are susceptible to low concentrations of 1-methyl-4-phenylpyridine (MPP+) via impairment of energy metabolism.

Selective dopaminergic neurotoxicity induced by 1-methyl-4-phenylpyridine (MPP+) is believed to be due to the transmembrane uptake by the dopamine transporter and subsequent inhibition of mitochondrial complex I and/or production of free radicals. However, little is known about the molecular sequence of intracellular events leading to cell death induced by low concentrations of MPP+. Here we stably express the human dopamine transporter (hDAT) in human embryonic kidney HEK-293 cells to correlate cytotoxicity and indices of cellular energy metabolism after exposure to low concentrations of MPP+. The permanent ektopic expression of hDAT in HEK-293 cells confers time and dose-dependent cytotoxicity at nanomolar concentrations of MPP+ with an IC50 value of 740 nM after 48 h. MPP+ initially induces a fast increase of cellular NADH content within the first 6 h, followed by a slow reduction of intracellular ATP (IC50 value of 690 nM after 48 h) as well as reduction of intracellular ATP/ADP ratio. These changes of cellular energy metabolism precede reduction of cell viability. The toxic effects of MPP+ are blocked by the hDAT inhibitor GBR12909 with EC50 values of 110 and 60 nM for cytotoxicity and ATP depletion, respectively. Antioxidants such as D-alpha-tocopherol and ascorbic acid do not have significant protective effects against MPP+ toxicity. This study shows that HEK-293 cells expressing the hDAT gene are highly sensitive to MPP+ due to (i) transmembrane uptake of MPP+ by the dopamine transporter, (ii) cellular energy depletion, probably caused by inhibition of mitochondrial complex I activity and (iii) that the toxicity is independent from the presence of antioxidants. This cell system may serve as a screening system for endogenous and exogenous compounds with similar effects compared to MPP+ as well as protective agents.

1-Methyl-4-phenylpyridinium↗