[Relation of different food allergens to different age of asthmatic patients]

A total of 1,070 cases of bronchial asthma, age from 3 to 70 years, were analyzed for their hypersensitivity to the four most common food allergens, egg white, milk, shrimp and peanuts. The severity of hypersensitivity was classified as mild, moderate and severe based on the concentration of allergen specific IgE in the sera. Results showed that there were 16.2% patients allergic to egg white, 22.3% allergic to milk, 12.6% allergic to peanuts and 34.9% allergic to shrimp. The incidence and severity varied with age. For milk and egg white allergy, the age with highest incidence rate appeared to be under 10 years old. In this age group, there were 38.1% patients allergic to milk, 8.9% of them were moderate hypersensitivity and the rest were mild hypersensitivity. There were 27.3% patients allergic to egg white, 17.3% of them were moderate hypersensitivity and the rest were mild hypersensitivity. For shrimp and peanuts allergy, the age with highest incidence rate appeared to be 11 to 20 years old. In this age group, there were 51.9% patients allergic to shrimp, 42.9% of them were moderate hypersensitivity and the rest were mild hypersensitivity. There were 18.2% patients allergic to peanuts, 25.0% of them were moderate hypersensitivity and the rest were mild hypersensitivity. We concluded that different age of asthmatic patients were affected by different food allergen. Shrimp and peanuts allergy occurred later and more severe than milk and egg white allergy, however, most of them were mild hypersensitivity and might be only partially contributed to their asthmatic symptoms.

Melatonin potentiates the GABA(A) receptor-mediated current in cultured chick spinal cord neurons

The effect of melatonin on the gamma-aminobutyric acidA (GABA(A)) receptor-mediated response was studied in cultured chick spinal cord neurons using the whole-cell voltage-clamp recording technique. Melatonin rapidly and reversibly potentiated the GABA-induced current in a dose-dependent fashion, with an EC50 of 766 microM and a maximal potentiation of 148%. Potentiation of the GABA response by melatonin was mediated by increasing the potency of GABA rather than the efficacy. Prolonged exposure to a saturating concentration of the disulfide-reducing agent dithiothreitol did not attentuate the effect of melatonin on the GABA response, indicating that melatonin does not act through the redox site. Furthermore, our results demonstrate that melatonin and 5alpha-pregnan-3alpha-ol-20-one (a positive steroid modulator of the GABA(A) receptor) act through different sites.

Effects of ozone on ovalbumin sensitization in guinea pigs

The effects of ozone on allergen sensitization is still controversial. This study is aimed to clarify the effect of ozone on airway hypersensitivity to ovalbumin (OVA) in guinea pigs, by exposing them to ozone (3 ppm 2 hours daily) and OVA (1 gm/dL 10 min weekly) for two weeks. OVA specific IgG and airway hypersensitivity to methacholine were determined after the sensitization. The results demonstrated that there was a synergistic effect of ozone on OVA-induced IgG antibody production. OVA specific IgG was 0.51 +/- 0.1 U/mL and 0.46 +/- 0.1 U/mL using OVA and ozone alone respectively, which increased to 1.09 +/- 0.4 U/mL when both OVA and ozone were given simultaneously. Ozone exposure was able to cause airway hypersensitivity. The provocation dose of methacholine causing a 100% increase of airway resistance (PD 100 airway resistance) was 0.54 +/- 0.19 mg/mL and 1.17 +/- 0.30 mg/mL using OVA and ozone exposure alone, which had decreased to 0.49 +/- 0.18 mg/mL when both OVA and ozone were given simultaneously. There were macrophages around the peribronchial tissue in all guinea pigs except in the control. The macrophages in the group of OVA with ozone (24.2 +/- 7.2 cells/HPF) were significantly more than those in the OVA group (18.0 +/- 4.2 cells/HPF) and the ozone group (14.5 +/- 6.2 cells/HPF). When OVA-presensitized guinea pigs were exposed to ozone immediately or daily for two weeks, a restrictive type of lung function impairment with similar airway hypersensitivity post ozone exposure was observed. In conclusion, guinea pigs exposed to ozone in conjunction with aeroallergen may not only facilitate the damage of the airway but also enhance antibody production to the aeroallergen. The ozone-induced airway inflammation might have a contributing effect on OVA induced airway hypersensitivity in guinea pigs.

Denaturation of ovalbumin abrogates oral induction of airway hyperreactivity and IgG1, IgG2 antibody responses in guinea pigs

BACKGROUND

The effects of denaturation of ovalbumin (OVA) on the induction of oral sensitization in guinea pigs were examined.

METHODS

Guinea pig antibody and airway responses were assessed after 10 feedings of chemically or heat-denatured OVA or egg white (EW).

RESULTS

Their specific IgG, IgG1 and IgG2 antibody responses were orally sensitized by OVA or EW, but not by chemically or heat-denatured OVA or EW. When further exposed to 0.1% OVA or conalbumin aerosol, those fed OVA or EW, but not denatured OVA or EW, had increased pulmonary resistance and decreased tidal volume. On the other hand, in those fed denatured OVA, boiled EW or saline only, a second sensitization with 1% OVA aerosol generated antibody responses and airway hyperreactivity. Using a sandwich ELISA, guinea pig serum OVA was detected after feeding EW, but not chemically denatured or boiled EW.

CONCLUSIONS

It is likely that guinea pig gut absorption of OVA may result in oral sensitization. Chemical or heat denaturation of proteins may minimize their intestinal uptake and thus abrogates the induction of oral sensitization in guinea pigs.

Hypersensitivity of bronchial asthmatics to cockroach in Taiwan. comparative study between American and German cockroaches

This study was performed to test the hypersensitivity of asthmatics to American and German cockroaches, which are both common in Taiwan. A total of 236 asthmatic patients received skin prick test using allergen extracts from both American and German cockroaches, and 596 sera from asthmatic patients were analyzed for their specific IgE against German cockroach extract. The results of skin test showed that 39.4 and 36.4% asthmatic patients were hypersensitive to American and German cockroaches. Fifteen among 236 patients were only allergic to American cockroaches and 8 were only allergic to German cockroaches. Using the Pharmacia CAP system, 36% of the sera were found to contain the specific IgE to German cockroach extract. Eighty-nine sera positive for German cockroach extract were then tested for their reactivity to American cockroach extract using the fluoroallergosorbent test (FAST). Sixty among 89 (68%) of their sera contained American cockroach-specific IgE. The correlation coefficient between both parameters was r = 0.45. Immunoblot and immunoblot inhibition studies were performed to analyze the IgE-binding components and the cross-reactivity between American and German cockroaches. The results showed that there are different IgE-binding components between American and German cockroaches. Sera containing specific IgE to both species of cockroach were absorbed with both species of cockroach extracts. The specific IgE to German cockroaches can be absorbed by American cockroach extract in all selected sera and the specific IgE to American cockroaches can only partially be absorbed by German cockroaches. The nonabsorbed allergens in American cockroaches had molecular weights of 33 and 50 kD. In conclusion, one-third of the asthmatic population tested was allergic to cockroaches. Although most cockroach-hypersensitive patients were allergic to both American and German cockroaches, more asthmatic patients were allergic to American cockroaches in Taiwan. The use of non-crossreacting allergen in detecting American cockroach-specific IgE might be important not only for the diagnosis and treatment of cockroach hypersensitivity in asthmatics but also for the differentiation between German and American cockroach hypersensitivity.

Clinical manifestations of 20 Taiwanese patients with paroxysmal kinesigenic dyskinesia

INTRODUCTION

We compared the clinical manifestations and response to medications between familial and sporadic patients with paroxysmal kinesigenic dyskinesia (PKD), and also between patients with autosomal dominant (AD) and autosomal recessive (AR) inheritance.

MATERIAL AND METHODS

This retrospective cohort study included 9 familial and 11 sporadic Taiwanese patients with PKD diagnosed during a 10-year period at one of two hospitals. The mean duration of follow-up was 3.8 +/- 2.7 years. Each patient was interviewed and their medical records, as well as videotape recordings of PKD attacks in 6 patients, were used for analysis. Patients were treated with either carbamazepine or phenytoin, and the efficacy of sodium valproate was tested in 5 patients.

RESULTS

No single distinguishing feature in terms of clinical manifestations or therapeutic response was found to differentiate among familial, and sporadic cases, or between AD and AR inheritance. Carbamazepine and phenytoin were superior to sodium valproate in treating both familial and sporadic PKD patients, and both drugs resulted in almost complete remission of attacks.

CONCLUSION

Our findings indicate that the sporadic and familiar forms of PKD, as well as the AR and AD inherited types, are similar in terms of clinical manifestations and response to treatment. The functional status and prognosis of our Taiwanese patients suggest that PKD is a relatively benign entity.

Frequency-dependent inhibition of neuronal activity by topiramate in rat hippocampal slices

1. Topiramate is a structurally novel anticonvulsant which was recently approved for adjunctive therapy in partial and secondarily generalized seizures. The present study was aimed at elucidating the mechanisms underlying the anticonvulsant efficacy of topiramate using intra- and extracellular recording techniques in the in vitro hippocampal slices. 2. When stimuli were delivered every 20 s, topiramate had no measurable effect on both field excitatory postsynaptic potentials (fEPSPs) and population spikes (PSs). However, increasing the stimulation frequency from 0.05-0.2 Hz, topiramate significantly decreased the slope of fEPSP and the amplitude of PS in a concentration-dependent manner. The amplitude of presynaptic fiber volley was also reduced. 3. Topiramate did not affect the magnitude of paired-pulse inhibition and monosynaptically evoked inhibitory postsynaptic potentials (IPSPs). 4. Sustained repetitive firing was elicited by injection of long duration (500 ms) depolarizing current pulses (500-800 pA). Superfusion with topiramate significantly reduced the number of action potentials evoked by a given current pulse. 5. After blockade of GABA receptors by bicuculline, burst firing which consisted of a train of several spikes riding on a large depolarizing wave termed paroxysmal depolarizing shift (PDS) was recorded. Application of topiramate reduced the duration of PDS and later spikes with less effect on the initial action potential. 6. These results suggest that frequency-dependent inhibition of neuronal activity due to blockade of Na+ channels may account largely for the anticonvulsant efficacy of topiramate.

Genetic analysis of interleukin-10 promoter region in patients with systemic lupus erythematosus in Taiwan

Overproduction of interleukin-10 (IL-10) may play an important role in the development of systemic lupus erythematosus (SLE) or lupus nephritis. There is also a polymorphic dinucleotide repeat in the human IL-10 promoter region (IL-10PR). Our aim was to study whether or not the IL-10PR alleles contributed to the susceptibility to SLE or lupus nephritis. One hundred SLE patients and 103 healthy controls were studied for IL-10PR by PCR and electrophoretic analysis. The distribution of IL-10PR alleles, genotypes and the sum of both alleles (SBA) from different groups or subgroups were analyzed. SLE patients showed no difference in the distribution of IL-10PR alleles, genotypes and SBA, as compared to healthy controls. Lupus nephritis patients (N = 49) also showed no difference in IL-10PR alleles, genotypes and SBA, as compared to SLE patients without nephritis (N = 51). Of 49 lupus nephritis patients, ten developed end-stage renal disease (ESRD) and four of them were found to suffer from rapid progressive renal failure (RPRF). Patients with RPRF presented much smaller SBA than other ESRD patients (p = 0.005). Lupus nephritis patients carrying small SBA (< 18) suffered from a higher prevalence of RPRF than lupus nephritis patients without small SBA (50% V.S. 0%, p < 0.001, relative risk 82). Our data provide the first evidence of a strong association between IL-10PR and severe progression of lupus nephritis in human patients. In the future, a prospective genetic analysis of IL-10PR for patients with lupus nephritis is recommended. It might be helpful for physicians to identify the lupus nephritis subgroup with a high risk of developing RPRF early, because this might lead to a better therapy and prognosis for these patients.

Airway hyperreactivity modulated by immunotherapy with denatured ovalbumin in ovalbumin-sensitized guinea pigs

Denatured immunogenic peptides have recently been used successfully to treat autoimmune disease in mice. Their effect on airway response is unclear. In this study, we compared the effect of native ovalbumin (OVA) and denatured ovalbumin (DN-OVA) on airway spasm and hyperreactivity in guinea pigs. The effects of immunotherapy using DN-OVA were also investigated. Airway response to antigen was determined in conscious, nose-breathing guinea pigs. Results showed that animals could be sensitized by repeated exposure to OVA, but not DN-OVA. Following OVA exposure in OVA-sensitized guinea pigs, airway resistance was significantly increased in both early (30 min, 118.8% +/- 34.2%) and late (6 h, 91.1% +/- 30.1%) phases. Tidal volumes were reduced in both early (47.5% +/- 12.0%) and late (43.8% +/- 10.3%) phases. This dual-phase airway spasm could not be induced by DN-OVA. In addition, there was no change in pulmonary function noted after DN-OVA exposure in OVA-sensitized guinea pigs. OVA-induced airway response was modulated by immunotherapy with subcutaneous DN-OVA administration for 3 weeks. OVA-specific IgG was also increased after immunotherapy. However, there was no significant change in pulmonary function after oral administration of DN-OVA in OVA-sensitized guinea pigs. We conclude that OVA, but not DN-OVA, can successfully induce dual-phase airway spasm in guinea pigs. These reactions can be modulated by immunotherapy with subcutaneously administered DN-OVA.

Lamotrigine inhibits depolarization-evoked Ca++ influx in dissociated amygdala neurons

Spectrophotometry with the Ca(++)-sensitive dye fura-2 was used to study the effect of lamotrigine (LAG) on the depolarization-evoked Ca++ influx in the acutely isolated basolateral amygdala neurons. Depolarization of the neurons with high K+ resulted in the elevation of intracellular Ca++ concentration [Ca++]i in a concentration-dependent manner. The K(+)-induced Ca++ influx was completely blocked in the Ca(++)-free solution or by Cd++, indicating that depolarization-induced increases in [Ca++]i were triggered largely, if not at all, by Ca++ entry from extracellular space and Ca++ entry occurred through voltage-dependent Ca++ channels. Application of LAG reduced the depolarization-evoked Ca++ influx in a concentration-dependent manner. The effect of LAG was markedly reduced in the presence of N-type Ca++ channel blocker omega-conotoxin-GVIA (omega-CgTX). These results suggest that the action of LAG is mediated, at least in part, by the modulation of N-type Ca++ channels.

T cell receptor gene V alpha and V beta usage in patients with rheumatoid arthritis in Taiwan

To investigate the correlation of T cell receptor (TCR) genes to rheumatoid arthritis (RA) in Taiwan, synovial fluid and peripheral blood were examined simultaneously in 14 patients with RA, and peripheral blood only was examined in 15 healthy controls. RNA was extracted from T cell in synovial fluid and peripheral blood, and cDNA was synthesized using the reverse transcription method. Then, TCR-V alpha and V beta gene families were determined using the polymerase chain reaction and slot blot methods. The numbers of TCR-V alpha and V beta families, especially V beta, were decreased in rheumatoid synovial fluid compared with numbers found in the peripheral blood of the same RA patients. TCR-V beta 7 and V beta 8 could be found in the synovial fluid of all patients with positive HLA-DR4. However, there was no significant difference in the numbers of TCR-V alpha and V beta families in peripheral blood of RA patients and the peripheral blood of healthy controls. In conclusion, restricted heterogeneity of TCR-V gene, especially V beta, can be found in synovial fluid of patients with RA. TCR-V beta 7 and V beta 8 may be related to the pathogenesis of HLA-DR4 positive RA patients in Taiwan.

Alkaline serine proteinase: a major allergen of Aspergillus oryzae and its cross-reactivity with Penicillium citrinum

BACKGROUND

Aspergillus species are common indoor airborne fungi and have been considered as causative agents of human allergic disorders. However, allergens of different Aspergillus species have not been effectively characterized. The object of this study was to identify and characterize IgE-binding components of Aspergillus oryzae.

METHODS

Allergens of A. oryzae were identified by immunoblot analysis using sera from asthmatic patients. The N-terminal amino acid sequences of allergens thus identified were determined by Edman degradation. The antigenic and the allergenic cross-reactivities between allergens of different fungi were analyzed by immunoblotting and immunoblot inhibition analysis, respectively, using a monoclonal antibody (MoAb) 55A against the 33-kD major allergen of Penicillium citrinum and a mixture of IgE-containing asthmatic serum samples.

RESULTS

Thirteen components of A. oryzae ranging in apparent molecular weight from 16 to 42 kD react with IgE antibodies. A 34-kD component that showed intense IgE-binding reactivity and was detectable in the highest frequency in our asthmatic serum samples tested was considered a major allergen of A. oryzae. The 34-kD component also reacted with MoAb 55A. Results from immunoblot inhibition studies also demonstrated the IgE cross-reactivity between the 34-kD major allergens of A. oryzae and P. citrinum. In addition, the sequence of the N-terminal 18 amino acid residues of the 34-kD major allergen of A. oryzae was found to be identical to that of the alkaline serine proteinase from the same Aspergillus species.

CONCLUSION

The 34-kD major allergen of A. oryzae is an alkaline serine proteinase. There is IgE cross-reactivity between the major serine proteinase allergens of A. oryzae and P. citrinum.

Risk factors analysis for early fatality in children with acute bacterial meningitis

To identify the cause of early fatality and to delineate the clinical findings on admission associated with this early fatality, a retrospective study of 101 children with bacterial meningitis was performed in southern Taiwan. Risk factors for early fatality are compared between patients with and without acute death in the first 3 days after admission. The overall patient fatality is 27%. Eighty-five percent of them (23 patients) occur at an average of 16.5 hours after admission despite proper antibiotic treatment. The causes of early death are predominantly hemodynamic in 14 patients (61%) and predominantly neurologic in nine (39%). Analysis of clinical parameters available on admission indicated a significant risk of early death in patients who have tachycardia, tachypnea, hypothermia, poor skin perfusion, metabolic acidosis, leukopenia, thrombocytopenia, low cerebrospinal fluid leukocyte count, and high cerebrospinal fluid lactate level. Multivariate analysis demonstrates that metabolic acidosis, poor skin perfusion, and low cerebrospinal fluid leukocyte count are independently and significantly associated with early fatality. In conclusion, two thirds of early fatalities in children with bacterial meningitis are the result of septic shock. Close surveillance for signs of septic shock, as well as of brain herniation should be continued, especially within 3 days after antibiotic treatment.

Sensitization to Blomia tropicalis among asthmatic patients in Taiwan

House dust mites have been reported as one of the most important allergens in Taiwan especially in asthmatic patients. This study was conducted to determine the allergenicity of Blomia tropicalis and sensitization of asthmatic patients in Taiwan. Serial dust samples were collected every month between July 1993 and June 1994 from 13 houses of mite-allergic patients. About 1 m2 surface area of a quilt was vacuumed. The floating method was used to collect mites, then identification and counting were performed. Results showed that Dermatophagoides pteronyssinus and B. tropicalis were the two most common species of mites found in allergenic patients' houses in Taipei. D. pteronyssinus accounted for 52.1% of the total number of mites and was found in every house. B. tropicalis, although not present in every sample, accounted for 44.3% of the total number of mites. The skin test positive reaction to B. tropicalis, D. pteronyssinus and Dermatophagoides farinae were 73.3, 88.3 and 85.0% as determined from 60 allergic patients who attended our allergy clinics. The extract prepared from B. tropicalis was used to determine the allergenicity and contained at least 30 protein components when silver stained. The most frequently detected allergens were proteins with molecular weights of 14.3, 106.5, 94.0, 72.0, 91.9, 63.7, 100.3, 43.6, 27.3, 62.0, 34.7, 18.3, 41.1 and 21.9 kD. The frequency of IgE binding of patient sera to those proteins were 87.0, 65.2, 56.5, 43.4, 39.1, 39.1, 34.8, 30.4, 30.4, 17.4, 17.4, 17.4, 13.0 and 8.7%. The results from immunoblot inhibition showed that there was IgE cross-reactivity among the B. tropicalis and D. pteronyssinus. However, there were two major allergenic components of B. tropicalis not inhibited by D. pteronyssinus with molecular weights of about 14.3 and 27.3 kD. The use of B. tropicalis extract for diagnostic purposes to identify patients with specific sensitivity should be considered in Taiwan.

Initial estimation methods for dipole modeling in localization of epileptogenic focus

Although great sensitivities to initial estimates is an inherent feature of iterative dipole optimization algorithms, the study of better initial estimates has been neglected. For convergence to a correct solution, the initial estimates should be extremely close to the desired solution and be attributed to only a single dipole focus. To alleviate the interference of background and multiple foci, the singular value decomposition (SVD) technique is used initially to extract the dominant component of the EEG spike for dipole localization. By observing the three-dimensional topographic mapping, the initial estimates of the dipole parameter set can be computed from the intersection between the null potential plane and from the peak and valley potentials. This work also compares initial estimations of simulation data, including noisy data, noisy data with SVD process and noise-free data. Experimental results confirm that good initial estimates for the dipole parameters are necessary to ensure rapid convergence to the correct solution.

Mechanism underlying potentiation by progesterone of the kainate-induced current in cultured neurons

The effect of the neurosteroid progesterone on the kainate receptor-mediated response was studied in cultured chick spinal cord neurons using the whole-cell voltage-clamp recording technique. Progesterone rapidly and reversibly potentiates the kainate-induced current in a dose-dependent manner, with an EC50 of 35 microM and a maximal potentiation of 30%. Potentiation of the kainate response by extracellularly applied progesterone is not significantly affected by inclusion of a saturating concentration of progesterone in the electrode buffer, indicating that progesterone acts at the extracellular surface of the membrane. Furthermore, progesterone enhances the kainate maximal response with little effect on the kainate EC50.

Object-based and location-based shifting of attention in Parkinson's disease

Research into Parkinson's disease has made much use of the precuing paradigm developed by Posner to examine patients' ability to shift visuospatial attention. The majority of studies indicate that patients with Parkinson's disease have significantly reduced shift costs when compared with normal controls. This reduction in costs is ascribed to abnormal maintenance of attention resulting from Parkinson's disease. We know that visual attention is not directed to spatial locations alone but that it may also be directed to object representations. To date, however, it has not been clear whether the reduced shift costs apparent in Parkinson's disease patients are evident only on spatial locations or on both spatial locations and object representations. Therefore, in the current study we have adopted a new technique with a view to studying both location-based and object-based attentional components within the same paradigm. Our results with 17 patients with Parkinson's disease suggest, at least in the early stages, patients do not show deficits in maintenance of attention to the miscued source of stimulation as reflected in their normal magnitude of cuing effect related to shifting between locations and between objects. 14 normal persons were control subjects.

Comparison of major aeroallergens in Taipei and Kin-Men

Ragweed pollen is an important aeroallergen in the USA, however, its role in the pathogenesis of allergic airway diseases in Taiwan has not been reported. Recently, a dramatic increase in patients with allergic rhinitis was noted in Kin-Men. Most patients had characteristic seasonal variation with the symptoms waxing in August and waning in November, which correlated with the pollen season of ragweed. The aim of this study was to clarify the role of ragweed pollen in the pathogenesis of allergic airway disease in Taipei and Kin-Men. Ragweed pollen from Kin-Men was collected, extracted, and resuspended in phosphate-buffered saline for a skin prick test. Greer ragweed pollen extract was used as a control. Serum from patients with a positive skin test was investigated for the ragweed pollen-specific immunoglobulin E (IgE). The IgE-binding components in the ragweed pollen were determined using immunoblot analysis. Of 101 patients from Kin-Men, 79 responded to ragweed. Only eight of 117 patients from Taipei responded to the same allergen. The titers of ragweed-specific IgE antibodies in the sera from Kin-Men were much higher than in the sera from Taipei. The response rate to the most common indoor allergen, Dermatophagoides pteronyssinus, was much lower in Kin-Men than in Taipei (25.7% and 90.6%, respectively). Thus, there were different aeroallergens in Kin-Men and Taipei. Having what was in both cases a Chinese population affected by different allergens indicates that environmental allergens may play an important role in the pathogenesis of allergic airway diseases. These results may also serve as a reference for the prophylaxis of allergic rhinitis in Kin-Men.

Lamotrigine inhibits tetraethylammonium-induced synaptic plasticity in the rat amygdala

Although long-term potentiation was generally initiated by a brief tetanus, in the hippocampus, it could also be evoked by application of the K+ channel blocker tetraethylammonium. The present study was aimed at investigating the effect of lamotrigine, a new anticonvulsant, on the tetraethylammonium-induced potentiation in brain slices of the rat amygdala using intracellular recording techniques. Bath application of tetraethylammonium (20 mM) for 10 min resulted in a long-lasting enhancement of the amplitude of excitatory postsynaptic potentials to 235 +/- 12% of control (n = 6, P < 0.001). Pretreatment of the slices with nifedipine (10 microM) abolished the potentiation, suggesting that tetraethylammonium long-term potentiation in the amygdala is due to Ca2+ influx through voltage-dependent Ca2+ channels. By contrast, N-methyl-D-aspartate receptor activation was not required because D-2-amino-5-phosphonovalerate (50 microM) did not prevent the tetraehylammonium long-term potentiation. Superfusion of lamotrigine (50 microM) depressed the excitatory postsynaptic potential to 53.8 +/- 3.9% of control. Tetraethylammonium was subsequently added in the presence of lamotrigine but failed to enhance the excitatory postsynaptic potential. Bursts of Ca2+ spikes evoked by a depolarizing pulse or by synaptic stimulation under tetraethylammonium were depressed by lamotrigine. It is concluded that lamotrigine is capable of inhibiting tetraethylammonium-induced synaptic plasticity. The underlying mechanism is likely due to lamotrigine's inhibition of postsynaptic voltage-dependent Ca2+ channels. Considering that tetraethylammonium is a convulsant agent and brief seizure episodes induced long-term potentiation, fibre sprouting and the development of aberrant synaptic contacts, lamotrigine could be a potential neuroprotective agent, especially in pathological situations where excessive glutamate release occurs.

Effects of phenytoin on the amygdala neurons in vitro

The present study was aimed at elucidating the possible mechanisms underlying the anticonvulsant efficacy of phenytoin using intracellular recording techniques in the in vitro amygdalar slice preparation. Synaptic response mediated by the N-methyl-D-aspartate (NMDA) receptor (EPSPNMDA) was isolated pharmacologically by application of a solution containing non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (10 mumol/l) and gamma-aminobutyric acidA receptor antagonist bicuculline (20 mumol/l). Phenytoin inhibits the amplitude of EPSPNMDA without affecting the postsynaptic depolarization induced by exogenous application of NMDA. In addition, phenytoin increases the magnitude of paired-pulse facilitation which is consistent with a presynaptic mode of action. These results suggest that inhibition of transmitter release due to presynaptic blockade of Na+ and/or Ca2+ channels may account largely for the anticonvulsant efficacy of phenytoin.

Molecular cloning and expression of a Penicillium citrinum allergen with sequence homology and antigenic crossreactivity to a hsp 70 human heat shock protein

BACKGROUND

Penicillium citrinum has been identified as the most prevalent airborne Penicillium species in the Taipei area. However, detailed studies on allergens of this ubiquitous Penicillium species are still lacking.

OBJECTIVE

For the characterization of allergens of this prevalent Penicillium species, molecular cloning and expression of the allergen genes of P. citrinum were performed in the present study.

METHODS

Molecular cloning of the allergen genes was performed by using a lambda Uni-Zap XR cDNA library of P. citrinum and serum from an asthmatic patient. The cloned cDNA was excised from the phage vector as a recombinant pBluescript phagemid and sequenced. The cDNA of the IgE-binding clone was expressed as fusion protein with the glutathione-S-transferase. The corresponding natural allergen was analysed by absorption immunoblotting using monoclonal antibody and serum from asthmatic patient. The frequency of IgE-binding to the allergen cloned was analysed by dot immunoassay using recombinant allergen and by immunoblotting using the whole extract of P. citrinum.

RESULTS

In the screening of cDNA library of P. citrinum using serum from an asthmatic patient, IgE-binding cDNA clones designated SC4 and XL were obtained. The 5'-truncated, 0.7-kb and 1.7-kb cDNA inserts of clones SC4 and XL contained open reading frames of 163 and 503 amino acids, respectively. On alignment, the deduced amino acid sequences showed that 97 (60%) of the 163 amino acids and 376 (75%) of the 503 amino acids were identical to the corresponding amino acid sequence of the human heat shock protein in the hsp70 family. Both recombinant SC4 and XL showed positive SDS-PAGE-immunoblot reactivity to a monoclonal antibody MA3-006 against the human hsp 70 protein. For characterization of the corresponding natural allergen, immunoblotting reactivities of MA3-006 and IgE antibodies to the 70 kDa component of P. citrinum have been shown to be disappeared after absorption of these antibodies with the recombinant SC4 protein. Sera from 14 (41%) of 34 Penicillium-allergic patients showed IgE-binding to the recombinant XL protein and the 70 kDa component in the extract of P. citrinum.

CONCLUSION

Results obtained suggest that hsp 70 is an allergen of P. citrinum and that clones SC4 and XL contain partial cDNAs of this allergen gene.

L-deprenyl (selegiline) limits the repetitive firing of action potentials in rat hippocampal CA1 neurons via a dopaminergic mechanism

The effects of L-deprenyl (selegiline), a highly selective monoamine oxidase type B (MAO-B) inhibitor, on cell excitability of rat hippocampal CA1 neurons were examined in slice preparations using intracellular recording techniques. Superfusion of L-deprenyl (10 and 20 microM) reversibly limited the repetitive firing (RF) of action potentials elicited by injection of depolarizing current pulses (100 ms) into the pyramidal cells. At a concentration of 1-50 microM, L-deprenyl did not alter resting membrane potential or input resistance of the hippocampal CA1 neurons. The limitation of RF by L-deprenyl (20 microM) was accompanied by the reduction of the maximal rate of rise (Vmax) of the action potentials in a non-voltage-dependent manner. In 80% of recorded cells, application of L-deprenyl (20 microM) produced an increase in the amplitude and duration of afterhyperpolarization (AHP). The limitation of L-deprenyl on RF was mimicked by other MAO-B inhibitors, pargyline and 4-phenylpyridine. In addition, the ability of L-deprenyl to limit RF was not observed in the hippocampal CA1 neurons taken from dopamine (DA)-depleted rats. Moreover, we also observed that the L-deprenyl-induced limitation of RF was specifically antagonized by (+/-)-7-bromo-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzaz epine (SKF-83566, 5 microM), a selective D1 dopaminergic receptor antagonist. However, the D2 dopaminergic receptor antagonist, sulpiride (5 microM), had no effect on L-deprenyl's action. These results indicate that the MAO-B inhibitory ability leading to an increase of the dopaminergic tone in the hippocampus is involved, at least in part, in the L-deprenyl-induced reduction of neuronal excitability in the CA1 region of rat hippocampus and that the D1 dopaminergic receptor is involved in L-deprenyl's action.

Application of dipole modeling in localization of mesio-temporal epileptogenic focus

Improved methods for noninvasive localization of an epileptic focus, modeled as an electrical dipole, are developed in this research. For the head geometrical model, a three-dimensional (3-D) electromagnetic tracking system is utilized to measure the exact positions of electrodes. A nonlinear optimization technique, the Levenberg-Marquardt method, is adopted for dipole localization. For the optimization algorithm to converge to correct solution, the singular value decomposition (SVD) technique is used to extract the dominant component of the EEG spike for initial estimation and dipole localization. The localization results of varied montages, including standard 10-20 electrodes and enhanced temporal electrodes, with or without invasive sphenoid electrodes, are compared. Our experimental results indicate that dipole localization with enhanced temporal electrodes can be used as an alternative for the invasive sphenoid electrodes to differentiate the epileptogenic foci of mesio-temporal area from temporal convexity.

Competitive inhibition of the glycine-induced current by pregnenolone sulfate in cultured chick spinal cord neurons

The effect of the neurosteroid pregnenolone sulfate (PS) on the glycine receptor-mediated response was studied in cultured chick spinal cord neurons using the whole-cell voltage-clamp recording technique. PS rapidly and reversibly inhibits the glycine-induced current in a dose-dependent manner, with an EC50 of 3.7 microM and a maximal inhibition of 100%. The fact that antagonism of the glycine response by PS is neither voltage- nor agonist-dependent indicates that PS does not act as an open-channel blocker. Furthermore, inhibition by PS of the glycine-induced current appears to be of a competitive type since the drug induces a parallel, rightward shift of the glycine dose-response curve.

HLA-DMA and DMB genotyping in patients with rheumatoid arthritis

OBJECTIVE

To investigate the relation of HLA-DMA and DMB alleles to the development of rheumatoid arthritis (RA).

METHODS

We studied HLA-DMA and DMB alleles in 153 patients with RA and 138 healthy controls using the amplification created restriction site method and digestion with restriction enzymes.

RESULTS

There was no significant difference in frequencies of HLA-DMA and DMB alleles between patients with RA and controls. The HLA-DMA and DMB alleles were not related to extraarticular involvement, seropositivity for rheumatoid factor, or bone erosion. There was also no significant difference in frequencies of HLA-DMA and DMB alleles among DR4-positive and DR4-negative patients and controls.

CONCLUSION

HLA-DMA and DMB do not appear to be associated with the pathogenesis of RA.