Acute bilateral cerebellar infarcts in the territory of posterior inferior cerebellar artery

The authors report 12 patients with acute bilateral cerebellar infarcts in posterior inferior cerebellar artery (PICA) territory. They found three topographic patterns: A) bilateral medial PICA in six patients; B) unilateral whole + contralateral medial PICA in four; and C) bilateral small multiple in two. Nine patients in Groups A and B had unilateral PICA or vertebral artery disease, and both patients in Group C had bilateral vertebral artery disease. These findings support that unilateral supply to both medial PICA territories may be the most relevant pathogenesis of this syndrome.

Carcinoma erysipelatoides originating from stomach adenocarcinoma

Carcinoma erysipelatoides is an uncommon form of cutaneous metastasis, which is most commonly caused by breast carcinoma, it has rarely been linked to the primary cancers of other organs. We report a 36-year-old woman with carcinoma erysipelatoides originating from a gastric carcinoma. Immunohistochemical and morphologic studies of skin biopsies revealed that the signet ring cells in the dilated lymphatics originated from adenocarcinoma of the stomach.

Clinical feature and outcome of pediatric cerebrovascular disease: a neurosurgical series

To investigate the clinical features and surgical outcome of pediatric cerebrovascular disease (CVD), we retrospectively reviewed 280 children (up to 15 years of age) who underwent neurosurgical procedures for CVD between 1979 and 1998. Open surgery (n=448), endovascular procedures (n=22), and stereotactic radiosurgery (n=14) were the main neurosurgical procedures adopted. Clinical features and surgical outcomes were described according to the etiology of the CVD and the number of years of management. The mean duration of follow-up was 34 months. The mean age was 7.1 years, and the male-to-female ratio was 1.2:1. The most frequent CVD was moyamoya disease (62%). The surgical mortality related to CVD was 0.7%. Eighty-seven percent had Karnofsky Performance Scale scores of more than 70. We demonstrate increasing detection rates and improving outcomes in recent years. The clinical course in this study shows that recovery from CVD in children is good after neurosurgical procedures.

Neck infection associated with pyriform sinus fistula: imaging findings

BACKGROUND AND PURPOSE

Acute suppurative neck infections associated with branchial fistulas are frequently recurrent. In this study, we describe the imaging findings of acute suppurative infection of the neck caused by a third or fourth branchial fistula (pyriform sinus fistula).

METHODS

Imaging findings were reviewed in 17 patients (11 female and six male patients, 2 to 49 years old) with neck infection associated with pyriform sinus fistula. Surgery or laryngoscopic examination confirmed the diagnoses. Fourteen patients had a history of recurrent neck infection and seven had cutaneous openings on the anterior portion of the neck (all lesions were on the left side). Imaging studies included barium esophagography (n = 16), CT (n = 14), MR imaging (n = 2), and sonography (n = 3).

RESULTS

A sinus or fistulous tract was identified in eight of 16 patients on barium esophagograms. In 14 patients, CT studies showed the inflammatory infiltration and/or abscess formation along the course of the sinus or fistulous tract from the pyriform fossa to the thyroid gland. In nine patients, CT scans showed the entire course or a part of the sinus or fistulous tract as a tiny spot containing air. MR images showed a sinus or fistulous tract in two patients, whereas sonograms could not depict a sinus or fistulous tract in three patients. All 17 patients were treated with antibiotics. In one patient, the sinus tract was surgically excised, while 15 patients underwent chemocauterization of the sinus or fistulous tract with good outcome. Follow-up was possible for 16 of the 17 patients.

CONCLUSION

When an inflammatory infiltration or abscess is present between the pyriform fossa and the thyroid bed in the lower left part of the neck, an infected third or fourth branchial fistula should be strongly suspected.

Onychomycosis and Trichosporon beigelii in Korea

BACKGROUND

Onychomycosis is a common superficial fungal infection. Causative organisms in onychomycosis have been extensively studied, but the role of nondermatophytes is controversial. Trichosporon beigelii is a soil and water inhabiting yeast and is occasionally found in the flora normally associated with human skin, mouth, and nails. Several reports in the literature have suggested that T. beigelii is one of the pathogens in onychomycosis.

METHODS

We performed a survey of the mycologic laboratory records of patients clinically suspected of having onychomycosis from July 1996 to December 1998.

RESULTS

Out of a total of 2591 nail samples examined, 1222 (47.2%) were culture positive, including 262 cases (10.1%) with T. beigelii. The overall positive rate for the KOH mount examination was 58.8%, and in the cases with T. beigelii was 89.1%. Among the age groups, the incidence rate was highest in the fifth decade (26.6%). The most common causative organism of microscopy-positive onychomycosis was Trichophyton rubrum (61.4%); the others in decreasing frequency were T. beigelii (20.4%), Candida spp. (7.3%), Trichophyton mentagrophytes (4.1%), and mixed infection (2.9%). T. beigelii was repeatedly isolated in successive nail cultures from 10 of 20 patients selected from those with T. beigelii nail infection.

CONCLUSIONS

T. beigelii was the second most commonly isolated fungus in onychomycosis and had a high positive rate on KOH mount examination of the nails and successive repeated cultures. We suggest that T. beigelii might be a common pathogen of onychomycosis in Korea.

A case of guttate psoriasis following Kawasaki disease

We report a case of guttate psoriasis following Kawasaki disease, in a patient with Staphylococcus aureus demonstrated in a throat swab. We suggest that preceding staphylococcal infection can play a key role in the pathogenesis of some cases of guttate psoriasis, possibly by the production of superantigens.

Constitutive activation of cyclin B1-associated cdc2 kinase overrides p53-mediated G2-M arrest

Recent studies have suggested that p53 regulates the G2 checkpoint in the cell cycle and that this function is required for the maintenance of genomic integrity. In this study, we investigated a regulatory role of p53 specifically in G2-M transition. Human bladder carcinoma cells lacking functional p53 were synchronized at G1-S, which is preceded by p53-mediated G1 arrest. p53 expression in the synchronized cells was induced by infection with a recombinant adenovirus that encodes p53. After release from the G1-S arrest, the cells progressed to S-phase and G2 but failed to enter mitosis. Biochemical analysis showed that p53 inhibits cell cycle-dependent expression of cdc2 and cyclin B1 and consequently inhibits cdc2 kinase. The role of cyclin B1-associated cdc2 kinase in p53-mediated G2-M arrest was further investigated by expression of both cyclin B1 and cdc2AF, in which inhibitory phosphorylation sites were substituted. The cells expressing both cdc2AF and cyclin B1 showed a constitutive activation of cdc2 kinase during cell cycle progression and passed through G2-M regardless of p53 expression. Therefore, inactivation of cdc2 kinase through cdc2 and cyclin B1 repression is an essential step in p53-mediated G2-M arrest.

In vivo proton magnetic resonance spectroscopy of central neurocytomas

OBJECTIVE

The authors report on the metabolic features of central neurocytomas observed during in vivo single-voxel proton magnetic resonance spectroscopy.

METHODS

Volume-selective single-voxel proton magnetic resonance spectroscopy was performed with a 1.5-T unit using a point-resolved spectroscopy sequence (TR/TE = 2000 ms/135 and 270 ms) to obtain spectra of a single 8-cc voxel. The subjects were five patients in the Department of Neurosurgery of Seoul National University Hospital whose central neurocytomas had been diagnosed histologically. The peak intensities of compounds containing choline (Cho), N-acetylaspartate, creatine/phosphocreatine, and lactate were analyzed.

RESULTS

The ratios of Cho to creatine/phosphocreatine and Cho to N-acetylaspartate were significantly higher than ratios in normal brains. A lactate signal was present, and an unidentified signal was also observed at 3.55 ppm, which might have been produced by inositol or glycine.

CONCLUSION

A combination of the signal at 3.55 ppm and a prominent Cho peak seems to be a characteristic feature of central neurocytomas. Volume-selective single-voxel proton magnetic resonance spectroscopy could provide additional information to aid in diagnosing this condition.

Usefulness of single voxel proton MR spectroscopy in the evaluation of hippocampal sclerosis

OBJECTIVE

The purpose of our study was to determine the ability of H-1 MR spectroscopy (MRS) to lateralize the lesion in patients with hippocampal sclerosis.

MATERIALS AND METHODS

Twenty healthy volunteers and 25 patients with intractable temporal lobe epilepsy whose MR imaging diagnosis was unilateral hippocampal sclerosis were included. This diagnosis was based on the presence of unilateral atrophy and/or high T2 signal intensity of the hippocampus. Singlevoxel H-1 MRS was carried out on a 1.5-T unit using PRESS sequence (TE, 136 msec). Spectra were obtained from hippocampal areas bilaterally with volumes of interest (VOIs) of 6.0 cm(3) and 2.25 cm(3) in healthy volunteers, and of either 6.0 cm(3) (n = 14) or 2.25 cm(3) (n = 11) in patients. Metabolite ratios of NAA/Cho and NAA/Cr were calculated from relative peak height measurements. The capability of MRS to lateralize the lesion and to detect bilateral abnormalities was compared with MR imaging diagnosis as a standard of reference.

RESULTS

In healthy volunteers, NAA/Cho and NAA/Cr ratios were greater than 0.8 and 1.0, respectively. In patients, the mean values of these ratios were significantly lower on the lesion side than on the contralateral side, and lower than those of healthy volunteers (p <.05). The overall correct lateralization rate of MRS was 72% (18/25); this rate was lower with a VOI of 6.0 cm(3) than of 2.25 cm(3) (64% versus 82%, p <.05). Bilateral abnormalities on MRS were found in 24% (6/25) of cases.

CONCLUSION

Although its rate of correct lateralization is low, single-voxel H-1 MRS is a useful and promising diagnostic tool in the evaluation of hippocampal sclerosis, particularly for the detection of bilateral abnormalities. To improve the diagnostic accuracy of H-1 MRS, further investigation, including the use of a smaller VOI and measurement of the absolute amount of metabolites, are needed.

MR imaging features of clear-cell meningioma with diffuse leptomeningeal seeding

Clear-cell meningioma is a rare disease entity showing a more aggressive nature, clinically, than those of other subtypes of meningioma. It occurs in younger persons and commonly in the spinal canal. The recurrence rate has been reported to be as high as 60%. We present a case of clear-cell meningioma in a 17-year-old man in whom initial MR imaging showed localized leptomeningeal enhancement that had progressed into the entire subarachnoid space after surgical resection of the primary tumor.

Virtual endoscopy using surface rendering and perspective volume rendering

Noninvasive virtual endoscopy is a new method of diagnosis using computer processing of 3-D image data sets (such as CT or MRI scans). Conventionally, two methods have been used in virtual endoscopy. One is 3-D surface rendering method. 3-D surface of human organs can be explored in real time by using this method, but surface rendering algorithm has disadvantages such as the low quality of visualized image and the loss of the volume data. The other is perspective volume rendering method. The power of perspective volume rendering is that the intrinsic 3-D richness of the volume data is preserved. However, there are the difficulty in planning flight-path and the disability of real time flight for a computationally intense procedure. This paper presents virtual endoscopy using both surface and perspective volume rendering. By combining each merits of two methods, a user can not only process virtual endoscopy interactively in real time but also view lossless and high-resolution image using the flight path defined by surface rendering. As a result, the use of common fly-paths removes the burden to define a flight-path in conventional perspective rendering method. Also 3-D object is explored in real time and viewed as lossless and detail cine sequences.

p53 negatively regulates cdc2 transcription via the CCAAT-binding NF-Y transcription factor

The p53 tumor suppressor protein regulates the transcription of regulatory genes involved in cell cycle arrest and apoptosis. We have reported previously that inducible expression of the p53 gene leads to the cell cycle arrest both at G(1) and G(2)/M in association with induction of p21 and reduction of mitotic cyclins (cyclin A and B) and cdc2 mRNA. In this study, we investigated the mechanism by which p53 regulates transcription of the cdc2 gene. Transient transfection analysis showed that wild type p53 represses whereas various dominant negative mutants of p53 increase cdc2 transcription. The cdc2 promoter activity is not repressed in cells transfected with a transactivation mutant, p53(22/23). An adenovirus oncoprotein, E1B-55K inhibits the p53-mediated repression of the cdc2 promoter, while E1B-19K does not. Since the cdc2 promoter does not contain a TATA sequence, we performed deletion and point mutation analyses and identified the inverted CCAAT sequence located at -76 as a cis-acting element for the p53-mediated regulation. We found that a specific DNA-protein complex is formed at the CCAAT sequence and that this complex contains the NF-Y transcription factor. Consistently, a dominant negative mutant of the NF-YA subunit, NF-YAm29, decreases the cdc2 promoter, and p53 does not further decrease the promoter activity in the presence of NF-YAm29. These results suggest that p53 negatively regulates cdc2 transcription and that the NF-Y transcription factor is required for the p53-mediated regulation.

Zn2+ differentially modulates kinetics of GABA(C) vs GABA(A) receptors in carp retinal bipolar cells

GABA(C) and GABA(A) receptors co-exist in retinal bipolar cells. In the present study the effects of zinc on the kinetics of currents mediated by GABA(C) and GABA(A) receptors were investigated in isolated carp bipolar cells, using whole-cell patch-clamp technique. We observed for the first time that zinc exerted opposite effects on kinetics of the GABA(C) and GABA(A) responses: zinc significantly slowed down activation and desensitization of the GABA(C) response, but accelerated those of the GABA(A) response; zinc dramatically accelerated deactivation of the GABA(C) response, whereas it had no apparent effect on deactivation of the GABA(A) response. These results suggest that zinc may be functionally important in regulating retinal signal transmission.

Sequential change of MR signal intensity of the brain after manganese administration in rabbits. Correlation with manganese concentration and histopathologic findings

RATIONALE AND OBJECTIVES

High signal intensity in the basal ganglia on T1-weighted MR imaging has been reported in chronic manganese (Mn) poisoning. However, the exact meaning of the high signal intensity remains unclear: does it result from Mn itself, secondary pathologic changes of the brain tissue, or both? The goal of this study was to evaluate the sequential change of MR signal intensity and to correlate the MR intensity of the globus pallidus and the hypothalamus with the Mn concentration in the blood and the brain tissue, and with the histopathologic findings.

METHODS

Ten milligrams per kilogram of Mn was administered once a week for 4 weeks to 14 rabbits. The rabbits in the control group (n = 2) were killed without Mn administration; those in group I (n = 4) were killed 1 day after the completion of Mn administration, those in group II (n = 4) were killed at 4 weeks, and those in group III (n = 6) were killed at 8 weeks. Sequential MR imaging, blood and tissue concentration measurement, and pathologic examination were performed. Sequential changes of the percent contrasts, contrast-to-noise ratios, and T1 relaxation times were analyzed with blood and tissue concentrations and histopathologic findings.

RESULTS

The signal intensity of the basal ganglia on T1-weighted imaging was highest 1 day after cessation of Mn administration and sequentially washed out. The contrast, contrast-to-noise ratio, and T1 relaxation time showed significant correlations with blood concentration. Only the T1 relaxation time of the globus pallidus showed a significant correlation with tissue concentration. Histopathologic examination disclosed mild abnormalities in the globus pallidus, thalamus, and hypothalamus.

CONCLUSIONS

The high signal intensity on T1-weighted MR imaging presumably indicates mainly the exposure marker of Mn, although mild pathologic findings were observed.

Craniofacial arteriovenous malformation: preoperative embolization with direct puncture and injection of n-butyl cyanoacrylate

PURPOSE

To evaluate the use of n-butyl cyanoacrylate (NBCA) for preoperative embolization of craniofacial arteriovenous malformation.

MATERIALS AND METHODS

Fourteen patients with craniofacial arteriovenous malformation (forehead [n = 9], deep facial [n = 3], occipital [n = 1], or lip [n = 1] lesion) were treated with injection of NBCA. Forehead lesions were supplied by ophthalmic (n = 6) and/or superficial temporal arteries (n = 7); and facial and scalp lesions, by bilateral internal maxillary (n = 4), facial (n = 2), and/or occipital arteries (n = 1). Lesions were percutaneously punctured with a 20-gauge needle in the area of arteriovenous connection. Direct angiography was performed before and after compression of venous drainage, and NBCA diluted 30%-50% with iodized oil was injected during venous compression.

RESULTS

Postembolization arteriograms showed that six lesions were completely devascularized after single or multiple (one to nine) injections, and five were effectively devascularized (> or = 90%). Although three lesions were 60%-70% devascularized after injection, two of these were successfully extirpated with no notable blood loss. In nine patients, the ophthalmic arterial supply had disappeared after embolization. There were no procedure-related complications.

CONCLUSION

Direct-puncture embolization with NBCA is an effective and safe technique for preoperative devascularization of craniofacial arteriovenous malformation. For safe and effective devascularization, compression of draining venous channels is thought to be important.

Comparison of MR imaging with PET and ictal SPECT in 118 patients with intractable epilepsy

BACKGROUND AND PURPOSE

MR imaging, PET, and ictal SPECT have been studied extensively as individual techniques in the localization of epileptogenic foci, but only a few comparative studies have been done. We evaluated the concordance rates of ictal video/EEG, MR imaging, PET, and ictal SPECT to compare the sensitivities of these imaging methods in the lateralization of epileptogenic foci.

METHODS

The study included 118 consecutive patients who underwent surgery for medically intractable epilepsy and who were followed up for 12 months or more. MR imaging was compared retrospectively with ictal video/EEG, FDG-PET, ictal 99mTc-HMPAO SPECT, and invasive EEG as to their ability to localize the epileptogenic focus; the pathologic findings served as the standard of reference.

RESULTS

MR imaging was concordant with video/EEG, PET, and ictal SPECT in 58%, 68%, and 58% of patients, respectively. With the pathologic diagnosis as the standard of reference, MR imaging, PET, and ictal SPECT correctly lateralized the lesion in 72%, 85%, and 73% of patients, respectively. Of the patients with good outcomes, MR imaging, PET, and ictal SPECT were correct in 77%, 86%, and 78%, respectively. In the good outcome group, MR imaging was concordant with PET and ictal SPECT in 73% and 62% of patients, respectively. Of 45 patients who underwent invasive EEG, MR imaging was concordant with the invasive study in 47%; PET in 58%; and ictal SPECT in 56%. Of 26 patients with normal MR findings, PET and ictal SPECT correctly lateralized the lesion in 80% and 55%, respectively.

CONCLUSION

Overall concordance among the techniques is approximately two thirds or less in lateralizing epileptogenic foci. PET is the most sensitive, even though it provides a broad approximate nature of the epileptogenic zone, which is not adequate for precise surgical localization of epilepsy. PET and/or ictal SPECT may be used as complementary tools in cases of inconclusive lateralization with ictal video/EEG and MR imaging.

Intracranial germinomas: correlation of imaging findings with tumor response to radiation therapy

OBJECTIVE

The purpose of this study was to correlate imaging characteristics of intracranial germinomas with response to radiation therapy.

MATERIALS AND METHODS

Using tumor size at the completion of irradiation, we classified 23 patients with histologically proven germinomas in the pineal gland (n = 6), the suprasellar region (n = 7), and the basal ganglia (n = 10) into two groups: excellent response group (n = 14) and good response group (n = 9). Excellent response was defined as complete resolution or residual tumor less than 1.0 cm in diameter, and good response was defined as residual tumor of 1.0-3.0 cm in diameter. CT (n = 53) and MR (n = 32) images obtained before, during, and after radiation therapy were retrospectively analyzed with particular attention to the location, size, presence of cystic change, and CSF seeding of the tumors.

RESULTS

In all 23 patients, the tumors decreased 85-100% in size at the completion of irradiation with 40-56 Gy. A significant factor in the different responses to irradiation between patients in the excellent and good response groups was cystic change of the tumor. Tumors with cystic components responded more slowly and had larger residual lesions than did tumors without cystic components (p < .01). In eight of 12 cystic tumors, the cystic portion of the tumor responded more slowly than did the solid portion and remained visible on imaging 6-12 months after irradiation. We found no significant differences between the two groups in location, size, and CSF seeding of tumors. In 12 patients with residual lesions at the completion of irradiation, the tumors proceeded to resolve after completion of treatment.

CONCLUSION

In our study, tumor response to radiation therapy correlated negatively with the presence of a cystic region.

An overview of biotechnology in Korea

During the 1980s and 1990s, Korea has invested heavily in biotechnology research and development, with the aim of becoming a leading nation in this field. It is important to understand the historical progress of this development in order to appreciate the current state of biotechology in Korea. However, it is equally important to know what research is currently being planned and carried out, and by whom.

[Response kinetics of GABA receptors and their functional significance]

It is an important issue whether and how the response kinetics, including activation, desensitization and deactivation, of gamma-aminobutyric acid (GABA) receptors plays roles in rapid inhibitory postsynaptic transmission. With the development of molecular biology, and the use of patch clamp techniques and rapid solution changers, the structural basis, underlying mechanisms at single channel level and functional roles of the characteristics of GABA receptors have been fully explored. It is revealed that the response kinetics of GABA receptors plays a crucial role in modulating inhibitory postsynaptic currents and has a great importance for rapid inhibitory synaptic transmission.

Focal lesion in the splenium of the corpus callosum in epileptic patients: antiepileptic drug toxicity?

BACKGROUND AND PURPOSE

Discrete focal lesions in the splenium of the corpus callosum on MR images in epileptic patients have received little attention in the literature. Our purpose was to describe these lesions, which may be related to the toxicity of antiepileptic drugs (AEDs), and to discuss the possible mechanisms of their development.

METHODS

We examined six patients with epilepsy whose brain MR imaging findings showed a discrete focal nonhemorrhagic lesion in the splenium of the corpus callosum. The medical records and MR images were reviewed retrospectively with respect to the patients' clinical history, medication, and laboratory findings to determine the etiology of the lesion.

RESULTS

In all six patients MR imaging showed a focal lesion in the splenium of the corpus callosum, which was ovoid in shape and 15 to 19 mm in size. In the three patients who received contrast material, there was no enhancement of the lesion. Four of six patients had a history of medication with dilantin, in two of whom the level of serum dilantin was found to be elevated (22.3 micrograms/mL and 70.4 micrograms/mL, respectively). Vigabatrin was administered in three patients, one of whom took dilantin together with vigabatrin. In two patients, the focal lesion in the corpus callosum disappeared on follow-up MR images after withdrawal of dilantin and/or vigabatrin.

CONCLUSION

A discrete, focal, ovoid, nonhemorrhagic lesion in the splenium of the corpus callosum may be seen on brain MR images of patients with epilepsy. The lesion is considered to be reversible demyelination related to AEDs toxicity.

The significance of CT scan or MRI in the evaluation of salivary gland tumors

Imaging modalities such as CT scan or MRI are frequently employed for the diagnosis of neoplastic lesions in the salivary glands. To evaluate the efficacy of the CT scan and the MRI in differentiating malignant neoplasm from benign lesions, 120 CT scans and 31 MRIs were retrospectively analyzed from 147 patients with salivary gland masses. All images were analyzed focusing on the presence of several relevant features. The pathologic results were matched with radiological features and also tabulated with radiological assessment. For the CT scans, the contour and margin of the lesion and tissue plane obliteration were found to be statistically significant indicators for malignant neoplasms. Among 69 CT scans interpreted as 'benign' by a radiologist, five cases (7%) were histologically diagnosed as 'malignant'. On the other hand, 20 out of 51 CT scans (39%) were misinterpreted as 'malignant'. For MRI, two out of 14 cases (14%) were radiologically misdiagnosed as 'benign' and six out of 17 patients (35%) as 'malignant'. In conclusion, whereas both the CT and MRI showed a similar level of accuracy in evaluation of salivary gland tumors, they showed a considerable tendency of misdiagnosis, especially by interpreting benign tumors as 'malignant'.

Brain abscess and necrotic or cystic brain tumor: discrimination with signal intensity on diffusion-weighted MR imaging

OBJECTIVE

The purpose of this study was to determine the differences in signal intensity between brain abscesses and necrotic or cystic tumors on diffusion-weighted MR imaging.

CONCLUSION

Five consecutive patients with proven brain abscesses and four patients with proven cystic or necrotic brain tumors were prospectively evaluated with diffusion-weighted imaging. On diffusion-weighted imaging, brain abscesses showed markedly hyperintense signal in all five patients, whereas necrotic or cystic brain tumors revealed hypointense signal in all four patients. Diffusion-weighted imaging may allow the differentiation of brain abscess from necrotic or cystic brain tumor.