Donor-π-donor type hole transporting materials: marked π-bridge effects on optoelectronic properties, solid-state structure, and perovskite solar cell efficiency.

Donor-π-bridge-donor type oligomers (D-π-D) have been studied intensively as active materials for organic optoelectronic devices. In this study, we introduce three new D-π-D type organic semiconductors incorporating thiophene or thienothiophene with two electron-rich TPA units, which can be easily synthesized from commercially available materials. A thorough comparison of their optoelectronic and structural properties was conducted, revealing the strong influence of the extent of longitudinal π-bridge conjugation on both the solid structure of the organic semiconductive materials and their photovoltaic performance when applied as hole transporting materials (HTM) in perovskite solar cells. Single-crystal measurements and time-resolved photoluminescence (TRPL) studies indicate that these coplanar donor-π-donor type HTMs could be promising alternatives to state-of-the-art spiro-OMeTAD, due to the multiple intermolecular short contacts as charge transporting channels and efficient charge extraction properties from the perovskite layer. The optimized devices with PEH-9 exhibited an impressive PCE of 16.9% under standard global AM 1.5 illumination with minimized hysteretic behaviour, which is comparable to that of devices using spiro-OMeTAD under similar conditions. Ambient stability after 400 h revealed that 93% of the energy conversion efficiency was retained for PEH-9, indicating that the devices had good long-term stability.

Solution immersed silicon (SIS)-based biosensors: a new approach in biosensing.

A novel, solution immersed silicon (SIS)-based sensor has been developed which employs the non-reflecting condition (NRC) for a p-polarized wave. The SIS sensor's response is almost independent of change in the refractive index (RI) of a buffer solution (BS) which makes it capable of measuring low-concentration and/or low-molecular-weight compounds.

Quality of life after radiosurgery for cerebral arteriovenous malformation patients who present with seizure.

BACKGROUND AND PURPOSE: This study assessed the quality of life (QOL) and employment status after radiosurgery for arteriovenous malformation (AVM) patients who presented with seizure. METHODS: Between 1997 and 2006, 78 AVM patients who presented with seizure and received radiosurgery were assessed using serial imaging tests, clinical evaluations that included employment status, and a QOL survey. The QOL questionnaire was developed as a retrospective screening tool to estimate the present QOL and the patient's self-rated relative changes (trend values) in QOL after radiosurgery. These results were correlated to one another using the Engel seizure frequency scoring system. RESULTS: The follow-up periods ranged from 48.0 to 151.0 months (mean, 92.5). The mean trend values and mean QOL scores in patients with seizure freedom or AVM obliteration were significantly greater than in patients without these outcomes (all P values < 0.05). Good radiosurgical outcomes were associated with attaining employment (all P values < 0.05). However, differences in employment status were not significant (P = 0.186) despite a higher proportion of patients who described their workplace activity as improved compared with their pre-radiosurgical activity at the last follow-up evaluation. CONCLUSIONS: Radiosurgery may improve QOL and employment status in AVM patients, especially patients who experience seizure freedom or AVM obliteration.

Pantothenate kinase-associated neurodegeneration in Korea: recurrent R440P mutation in PANK2 and outcome of deep brain stimulation.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the mutation status of PANK2 among Korean patients with pantothenate kinase-associated neurodegeneration (PKAN) and to document the outcome of pallidal deep brain stimulation (DBS). METHODS: Direct sequencing and deletion/duplication analysis of PANK2 were conducted in 12 patients (11 unrelated) with PKAN, diagnosed on the basis of extrapyramidal dysfunction and the 'eye-of-the-tiger sign' on brain magnetic resonance imaging (MRI). Pallidal DBS was conducted in four patients, and the outcomes were measured using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). RESULTS: A PANK2 mutation was identified in both alleles in all patients. The most prevalent mutation was c.1319G>C (p.R440P) in 8/22 mutated alleles (36%). An intragenic deletion ranging from exons 2 to 4 was found in one allele (1/22, 4.5%) using deletion/duplication analysis. The outcome of pallidal DBS was favorable in two patients with atypical PKAN and moderate severity of dystonia. However, two patients with typical PKAN and relatively severe symptoms showed variable responses. CONCLUSIONS: The c.1319G>C (p.R440P) mutation appears to be a founder genotype among Korean patients with PKAN. Furthermore, this study provides additional data for the recent international effort to evaluate the efficacy of pallidal DBS in the treatment of patients with PKAN.

Spinocerebellar ataxia type 17 mutation as a causative and susceptibility gene in parkinsonism.

OBJECTIVE: To investigate the role of spinocerebellar ataxia type 17 (SCA17) in the development of parkinsonism. METHOD: We screened 1,155 parkinsonian patients (931 with Parkinson disease and 224 with multiple system atrophy) and 400 normal subjects for SCA17. 99mTc-TRODAT-1 SPECT was used to evaluate the striatal dopamine transporter (DAT) status. RESULTS: Trinucleotide expansion in the SCA17 gene was found in 10 parkinsonian patients (8 with Parkinson disease, 2 with multiple system atrophy) using 42 repeats as an upper normal limit. The repeat sizes in the patients ranged from 43 to 46, which are considered to be low-range expansions. All patients had interrupted sequences. Three probands and three asymptomatic carriers underwent 99mTc-TRODAT-1 SPECT. Striatal DAT binding was markedly reduced in all probands and mildly decreased in one asymptomatic carrier. Among the 400 normal control subjects, there was one individual with an expansion of 44 repeats, another with 43 repeats, and two with 42 repeats. Striatal DAT binding was decreased not only in the control subjects with 44 or 43 repeats, but in ones with 42 repeats, suggesting that an expansion as low as 42 repeats might constitute a susceptibility gene for parkinsonism. CONCLUSIONS: Low-range expansion of the SCA17 gene is not a rare genetic cause of parkinsonism without ataxia in our population. Reduced penetrance or variable expressivity in low-range expansion might be an explanation for the blurred cutoff point for normal expansion in SCA17.

Evaluation of tumour response after gamma knife radiosurgery for residual vestibular schwannomas based on MRI morphological features.

OBJECTIVE: To evaluate tumour response after gamma knife (GK) radiosurgery for residual vestibular schwannoma (VS) based on MRI morphological features. METHODS: Sixty-one patients with histopathologically confirmed VS underwent GK radiosurgery with marginal tumour doses of 9.0-14.0 Gy (mean, 12.5). Mean tumour volume at GK radiosurgery was 3.65 ml (range, 0.52-15.50). GK radiosurgery was performed 0.3-95.7 months (median, 5.8) after microsurgery. Tumour volumes and half-reduction time were calculated using serial MRI. The morphological features of VS were documented by pre-microsurgical MRI. Histopathological investigation included Antoni-type dominance, the proliferation marker Ki-67 and tumour vascularity. RESULTS: Median duration of radiological follow-up was 53.7 months (range, 24.1-102.2) and the 8-year actuarial tumour control rate was 93.5%. No factor was associated with tumour control, although a cystic VS had borderline significance (p = 0.089). Mean tumour half-reduction time was 8.70 years (range, 0.57-79.89) and tumour half-reduction time in cystic VS proved to be significantly shorter than those in solid VS (p = 0.006). Thrombotic vessels (p = 0.015) and abnormal vessel proliferation (p = 0.003) were significantly more prominent in cystic VS than those in solid VS. CONCLUSIONS: GK radiosurgery appeared to be an effective treatment modality for residual tumour control after microsurgery. Owing to having relatively abundant tumour vascularity, residual solid portions of cystic VS resulted in efficient shrinkage after GK radiosurgery. Therefore, GK radiosurgery was found to be a rewarding therapeutic approach to the residual solid portions of cystic VS.

Isolation and characterization of outer root sheath melanocytes of human hair follicles.

BACKGROUND: Outer root sheath melanocytes (ORSM) are not yet routinely cultured and their biology is not known in detail because of their relatively low numbers in the hair follicle and their limited proliferative capacity in in vitro culture in routine media. OBJECTIVES: To develop a method for culturing ORSM more easily and to investigate the length of telomeres and antigenic characteristics of ORSM compared with epidermal melanocytes (EM). METHODS: Hair follicles were obtained from three Korean individuals during hair transplantation surgery. Single-cell suspensions of the outer root sheath were made and cultured in melanocyte growth medium with stem cell factor. After 21 days, second-passage outer root sheath keratinocytes (ORSK) (2 x 10(4) mL(-1) MGM) were added into the culture plates. We studied the proliferation pattern, morphological and antigenic characteristics of ORSM for each passage of cultured cells, and observed ORSM telomere length. RESULTS: We established an ORSM culture method using ORSK. Two morphologically different ORSM types were obtained in the primary cultures. At the end of primary culture, ORSM appeared as whitish-cream pellets. The proliferation pattern of ORSM showed a sigmoidal shape, the accumulated numbers of population doublings showed a plateau after approximately 5 months, and senescence occurred at approximately 33 +/- 5 accumulated population doublings. The length of ORSM telomeres continued to shorten as the cells proliferated. In contrast, EM showed a marked proliferation from the early proliferation period which formed a plateau pattern towards the later period, and the number of accumulated population doublings was estimated to be 18 +/- 5 after 2 months. ORSM in the primary culture reacted variably with l-dihydroxyphenylalanine (DOPA): some cells were DOPA negative, some DOPA positive. There were some different antigenic expressions of microphthalmia-associated transcription factor (MITF) showing cytoplasmic expression in ORSM and nuclear expression in EM. By nuclear extraction and Western blotting, we showed that MITF expression of ORSM was marked in the cytoplasm and minimal in the nucleus. Antigenic expression of MITF and Bcl-2 gradually decreased with increasing passage number, whereas tyrosinase-related protein-1 expression did not change. CONCLUSIONS: Culture of ORSM requires ORSK or ORSK-related factors; ORSM have greater proliferation potential and show different MITF antigenic expression compared with EM; and the length of ORSM telomeres shortens with repeated proliferation.

Clinical analysis of vertebrobasilar dissection.

BACKGROUND: The natural history of vertebrobasilar artery dissection (VAD) is not fully known. The purpose of this study was to review the clinical outcome of the patients with VAD, then to propose an appropriate management strategy for VAD. METHOD: From 1992 to 2004, 35 VAD patients admitted to our institutes were retrospectively reviewed. There were 28 men and 7 women, whose age ranged from 4 to 67 years with a mean age of 44 years. Angiography was assessed to document the shape, and location of the dissecting aneurysm with respect to the posterior inferior cerebellar artery (PICA). A modified Rankin score was assigned for functional outcome. The functional outcome scores were analyzed according to the patient's age, gender, hypertension history, the pattern of initial manifestation, angiographic shape of VAD, angiographic location of VAD, treatment modality. FINDINGS: There was no statistically significant difference between the functional outcome with age, gender, trauma history and past medical history of hypertension. Of 35 patients, 22 presented with SAH, 11 with ischemic symptoms and 2 were incidentally detected. The patients without SAH had a better functional outcome than those with SAH (p = 0.029). There was statistical significance between Hunt-Hess (H-H) grade and clinical outcome (p = 0.032). The shape and location of VAD was not significantly related to the functional outcome (p = 0.294, 0.840). But all the cases of rebleeding and mortality (except one case with initially poor H-H grade) developed exclusively in patients with aneurysms. There was no statistically significant correlation between the treatment modality and the outcome (p = 0.691). CONCLUSION: The VAD patients with SAH would be recommended to be managed by either surgical or endovascular treatment, but those without SAH, could be managed conservatively with antiplatelet therapy and/or anticoagulation.

Microcystic meningiomas: radiological characteristics of 16 cases.

BACKGROUND: As a rare subtype of meningioma, only a few reports deal with radiological characteristics of microcystic meningiomas and the problem remains controversial. The authors have analyzed the radiological findings of a series of microcystic meningiomas with a special focus on magnetic resonance images (MRI) and conventional angiography. METHOD: Sixteen patients of histologically proven microcystic meningiomas were included. Analysis of preoperative MRI including signal intensity characteristics, enhancement patterns and peritumoural edema were performed and correlated with angiographic and histological findings. Peritumoural edema was graded using edema index (EI) which was defined as the ratio of VE/VT. FINDINGS: The tumours were uniformly visualized as a high-signal mass lesion in T2-weighted images and as a low-signal mass lesion in T1-weighted images regardless of tumour vascularity shown by angiography. T2-weighted images revealed that peritumoural brain edema was severe in 11, moderate in 1, mild in 2 and negligible in 2 patients and this was closely related to the co-existence of irregular tumour marginal enhancement. However, other features failed to distinguish these lesions from other subtypes of meningioma. CONCLUSIONS: The cases presented demonstrate that characteristic MRI findings suggestive of microcystic meningiomas are; (1) low signal intensity mass in T1- and high signal intensity mass in T2-weighted images; (2) high incidence of peritumoural edema.

Delayed bleeding after gamma knife surgery for meningioma.

We report the occurrence of haemorrhage in a meningioma after gamma knife surgery.A 52-year-old woman had undergone gamma knife radiosurgery for a growing meningioma in the left tentorial hiatus three years earlier (A radiation dose of 15 Gy was administered to the margin, with a maximum dose of 30 Gy, Fig. 1a). The size of the mass decreased steadily, and central lucency was seen in the follow-up magnetic resonance images, a usual finding seen after gamma knife surgery (MRI, Fig. 1b). However, a MRI taken at the 30-month follow-up showed the tumour to be swollen, and peritumoural oedema had increased (Fig. 1c). Three years later, apoplectic symptoms occurred, and computed tomography revealed a peritumoural haemorrhage, with oedema (Fig. 1d). An emergency craniotomy was carried out, and the biopsy showed a transitional type of meningioma, with vasculopathy and necrosis. After operation she had a right hemiparesis and a visual defect.

The significance of gemistocytes in astrocytoma.

BACKGROUND: A retrospective clinical analysis of astrocytomas which contained a significant proportion of gemistocytes was carried out in order to evaluate their effect on prognosis, and other factors influencing prognosis. METHOD: From 253 consecutive cases of astrocytic tumours in adults, 25 were selected who had more than 20% gemistocytes in every high-power field examined. 9 of these had anaplasia, the remainder did not. They were divided into two groups according to the proportion of gemistocytes; group A, contained more than 60% gemistocytes, and group B, had between 20 and 60% gemistocytes. TUNEL and immunohistochemical staining for PCNA, p53, Ki-67, bcl-2 were performed in the 20 available cases. FINDINGS: The median follow-up period was 46 months. There were 14 recurrences, with a median time to recurrence of 15 months. Thirteen repeat operations were performed in nine cases, and two cases showed recurring malignant transformation. The overall median survival time following diagnosis was 73 months and the 5-year survival rate was 52%. There were no significant differences in median survival between groups A and B with different proportions of gemistocytes. On the other hand the median survival of the gemistocytic astrocytomas with anaplasia was 25 months, compared with 158 months for those without anaplasia (p=0.0005). The significant impact of anaplasia on survival persisted in both groups. There were no significant differences in immunohistochemical staining between the two groups, with the exception of staining for Ki-67 (means of the two groups: group A 1.40; group B 2.50). CONCLUSIONS: It is suggested that the proportion of gemistocytes does not itself affect prognosis.

Stereotactic biopsy for intracranial lesions: reliability and its impact on the planning of treatment.

BACKGROUND: The authors present a retrospective analysis of 308 computed tomography (CT)-guided stereotactic biopsies in 300 patients in order to evaluate the reliability and efficacy of the stereotactic biopsy for intracranial lesions. METHOD: All patients were suffering from undetermined intracranial lesions and treated at Seoul National University Hospital between January 1993 and December 1999. Age ranged from three to 79 years (mean 41); the male to female ratio was 180:120. All patients underwent CT-guided stereotactic biopsy for the histological verification and/or evacuation of the cyst using Riechert-Mundinger stereotactic system. FINDINGS: Histological diagnosis was made in 275 patients (diagnostic yield 91.7%). Diagnostic yield was better in group with frozen section examination during the stereotactic procedure than the group without it (p=0.01). Neoplastic lesions were more likely to be diagnosed in stereotactic biopsy than non-neoplastic lesions (p=0.02). Among 30 patients who underwent craniotomy after the stereotactic biopsy, the histological diagnoses after the craniotomy were identical to those of the stereotactic biopsy in 29 patients (diagnostic accuracy 96.7%). Two patients died within seven days after the stereotactic biopsy (mortality 0.6%). The postoperative new neurological deficit or aggravation of the neurological status was found in 19 patients, including transient cases of seven patients (permanent morbidity rate 3.9%). Histologically malignant gliomas and deeply-located lesions were the significant risk factors for the development of complications. In 148 cases, histological diagnosis of the stereotactic biopsy was different from the preoperative clinical diagnosis. Among these cases, the treatment plan was changed after stereotactic biopsy in 81 cases. CONCLUSIONS: Stereotactic biopsy for intracranial lesions is a reliable and relatively safe procedure. It is also a very efficacious method especially in patients who need histological confirmation for the treatment.

Changes in vascular responses of the basilar artery to acetylcholine and endothelin-1 in an experimental rabbit vasospasm model.

BACKGROUND: This study aimed to clarify the characteristics of the basilar arteries of rabbits two and seven days after subarachnoid haemorrhage (SAH) and to investigate the influence of hypoxia on vascular responses to acetylcholine and endothelin-1. METHODS: Thirty four New Zealand white rabbits were divided into 3 groups: 1) control (n=6), 2) 2 days post SAH (n=15), and 3) 7 days post SAH (n=13). Rabbits in the groups 2 and 3 underwent vertebral angiography before sacrifice. Harvested vascular rings were suspended in a small vessel myograph system for isometric tension recording in response to vasodilatory and vasoconstrictory stimulation in oxygenated (95% O2/5% CO2) and hypoxic (95% N2/5% CO2) conditions. To investigate the response to a vasodilator, acetylcholine (ACh) (10(-7) to 3 x 10(-4) M) was applied to a basilar artery pre-contracted with histamine (10(-6) approximately 10(-5) M). To investigate the response to a vasoconstrictor, the effect of endothelin-1 (ET-1) (10(-11) to 3 x 10(-8) M) was observed in quiescent rings. FINDINGS: Seven of 15 rabbits that underwent angiography two days after operation showed vasospasm to 64.3+/-11.2% of the original diameter; likewise seven of the 13 rabbits studied seven days after operation showed vasospasm to 64.9+/-10.9% of the original diameter. Hypoxic conditions significantly reduced the relaxation response to ACh but did not influence basilar artery contraction to ET-1. Responses to ACh and ET-1 did not differ significantly in vessels from animals with or without vasospasm at 2 days. In contrast, at 7 days vascular responses to ACh and ET-1 were significantly less in vessels from animals with vasospasm than those without (p=0.029, 0.032), and also less than in vessels from animals with vasospasm at day 2 (p=0.002, 0.004). There was not a significant difference in the vascular responses of basilar arteries from animals without vasospasm. INTERPRETATION: The markedly lower vascular responses of basilar arteries of rabbits to ACh and ET-1 found seven days after SAH may relate to delayed vasospasm in patients with SAH.

Radiosurgery of intracranial cavernous malformations.

BACKGROUND: The efficacy of radiosurgery in cases of surgically high risk symptomatic cavernous malformations (CMs) for reducing haemorrhagic risk and for seizure control has not been clearly documented and the radiation-induced complications of radiosurgery remain problematic. The authors present a retrospective clinical analysis of 22 cases of CMs treated by radiosurgery. METHODS: Twenty-two patients with symptomatic CMs were treated by linear accelerator (LINAC) radiosurgery or Gamma knife (GK) between 1995 and 1998. Medical records including radiological investigations were carefully reviewed to the last follow-up. The mean age of the patients was 34.1 years (12-56) and the male to female ratio was 12:10. Twenty patients reported at least one episode of bleeding and four had undergone microsurgery before radiosurgery. The remaining two patients presented with seizure without evidence of recent haemorrhage. In 16 cases, the CMs were deep-seated, and the others were located in the cerebral hemispheres; four were located at an eloquent area. LINAC radiosurgery using computed tomography scan was performed in 11 cases until May 1997, after which GK radiosurgery using magnetic resonance (MR) image was performed in 11 cases. The volume of the lesion ranged from 0.09 cc to 4.8 cc (mean 1.42 cc) and the mean marginal dose was 16.1 Gy (8-24). The median follow-up period after radiosurgery was 38.3 months (21-67). The rate of haemorrhage, seizure, and neurological deterioration following radiosurgery was analyzed, and the rate of haemorrhage was compared to that seen in natural course reports. FINDINGS: There was one case of haemorrhage during the follow-up period and the seizure was well controlled with anticonvulsants. In the group with prior haemorrhage, the bleeding rate of cavernous malformation after radiosurgery (1.55%/year) was lower than that of pre-radiosurgical period (35.5%/year, t=1.296, P=0.04). Six patients showed neurological deterioration following radiosurgery, however, the neurological deficits persisted in only two of the patients with LINAC. The radiosurgical modality (LINAC vs. GK) showed a possible correlation to radiation induced neurological deficits (P=0.06). On the MR images at the last follow-up, the lesion was decreased in eleven patients, increased in one, and no change was found in 10 cases. The T2 weighted MR images revealed a perilesional high signal change in nine patients. This signal change was not statistically related to lesion size (P=0.236), location (P=0.658), nor radiation dose (P=0.363), but was dependent on the treatment modality (P=0.02). New-enhancing lesion and a new cyst were each found in one case, respectively, during the follow-up. INTERPRETATION: Radiosurgery may be a good alternative option for treatment of surgically high risk CMs. However, the optimal radiosurgical technique, dose adjustment, and proper delineation of the mass are prerequisites. Radiosurgery induced complications are still problematic and post-radiosurgery MR image changes need to be further elucidated.

Cardiac surgery with deep hypothermic circulatory arrest produces less systemic inflammatory response than low-flow cardiopulmonary bypass in newborns.

OBJECTIVE: We sought to compare low-flow cardiopulmonary bypass with deep hypothermic circulatory arrest in respect to the influence on the systemic inflammatory response. METHODS: Twenty-three infants weighing less than 10 kg and scheduled for repair of congenital malformations were enrolled in a randomized, controlled study. Eleven patients underwent cardiac surgery with deep hypothermic circulatory arrest (the DHCA group). Low-flow cardiopulmonary bypass was used in another 12 patients (the LF group). Interleukin 6 and 8 and anaphylatoxin C3a levels were measured 6 times perioperatively. Also, perioperative weight gain and a radiologic soft-tissue index were compared. RESULTS: All patients had an uneventful clinical course. Duration of deep hypothermic circulatory arrest was 40 +/- 4 minutes; the bypass time was significantly shorter in the DHCA group (85 +/- 8 vs 130 +/- 19 minutes). However, the duration of the operation was similar in both groups (245 +/- 30 vs 246 +/- 30 minutes). During cardiopulmonary bypass (rewarming), the concentration of C3a (3751 +/- 388 vs 5761 +/- 1688 ng/mL, mean +/- SEM) was significantly lower in the DHCA group than in the LF group. The interleukin 8 level was significantly lower, and the interleukin 6 level had a tendency to be lower in the DHCA group compared with levels in the LF group. There was less weight gain on the first postoperative day in the DHCA group (65 +/- 61 vs 408 +/- 118 g). The soft-tissue index suggested reduced edema formation in the DHCA group. CONCLUSION: Deep hypothermic circulatory arrest produces less systemic inflammatory response than low-flow cardiopulmonary bypass. In addition, there is an indication of less fluid accumulation postoperatively.

Cerebral germinoma with hemiatrophy of the brain: report of three cases.

BACKGROUND: The authors report three cases of cerebral germinoma that occurred in young adults with unusual presentation. METHOD: All three patients presented with hemiparesis and were treated at Seoul National University. A histological diagnosis of germinoma was made by a stereotactic biopsy in all three cases. FINDINGS: Magnetic resonance (MR) images showed that their tumors were located in the internal capsule and thalamus, and were associated with ipsilateral cerebral hemisphere and brain stem atrophy. The hemiparesis slowly progressed and this was accompanied by a haemorrhagic cyst in each patient. INTERPRETATION: Clinical diagnosis was not easy because of the unusual clinical presentations and atypical MR imaging findings. It is suggested that cerebral germinoma should be included in the differential diagnosis of a haemorrhagic mass which is associated with cerebral atrophy in the thalamus, basal ganglia, or internal capsule, especially in adolescents or young adults.

Semiquantitative, bar code version of immunochromatographic assay system for human serum albumin as model analyte.

An immunochromatographic assay system was devised that can express the concentration ranges of analyte (e.g., urinary human serum albumin) as distinct numbers of the ladder bar (bar coding) for semiquantitation. We constructed a model system consisting of five membrane pad strips partially superimposed in a length. Upon wicking of sample from the bottom, the medium dissolved two different biotinylated species, antibody to the analyte and conjugates of the antibody with colloidal gold, and antigen-antibody reactions took place in the hollow space of the glass fiber membrane. After eliminating unreacted biotinylated molecules at the next strip with an immobilized albumin, the immune complexes were transferred to the pad with streptavidin immobilized in a ladder bar pattern. Analytical conditions here were set for competition between the two biotinylated species for the streptavidin binding sites. The degree of such competition was proportional to the analyte concentration and, consequently, the bar signal number was elevated as the concentration increased. Under optimal conditions for sensitivity, the analytical system responded to the analyte doses at between 30 and 120 mg/dL by producing different bar codes within 5 min.

Visual information processing using bacteriorhodopsin-based complex LB films.

Image extraction and visual information processing using bacteriorhodopsin (bR)-based bioelectronic devices is presented. Image extraction was achieved using a photoreceptor consisting of bR and spiropyran films. The undesired signals from the photoreceptor were automatically eliminated from the whole signal by spiropyran films acting as an optical noise filter that increases the target signal to an undesired signal ratio. For the information processing, the photoreceptor consisting of bR and lipid films deposited with different configurations was used and the target signals were processed to achieve the pattern recognition. The pattern recognition was based on not only the response variability of bacteriorhodopsin, induced by different film configurations, but also on the initial learning process. The input patterns were predicted by simple calculation with the known signals through the initial learning process.