CRISPR-Cas9 and beyond: identifying target genes for developing disease-resistant plants

Throughout the history of crop domestication, desirable traits have been selected in agricultural products. However, such selection often leads to crops and vegetables with weaker vitality and viability than their wild ancestors when exposed to adverse environmental conditions. Considering the increasing human population and climate change challenges, it is crucial to enhance crop quality and quantity. Accordingly, the identification and utilization of diverse genetic resources are imperative for developing disease-resistant plants that can withstand unexpected epidemics of plant diseases. In this review, we provide a brief overview of recent progress in genome-editing technologies, including zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9) technologies. In particular, we classify disease-resistant mutants of Arabidopsis thaliana and several crop plants based on the roles or functions of the mutated genes in plant immunity and suggest potential target genes for molecular breeding of genome-edited disease-resistant plants. Genome-editing technologies are resilient tools for sustainable development and promising solutions for coping with climate change and population increases.

Association between initial continuity of care status and diabetes-related health outcomes in older patients with type 2 diabetes mellitus: A nationwide retrospective cohort study in South Korea

BACKGROUND AND AIM

Timely and continuous care is necessary for patients with diabetes to prevent hospitalization and complications. This study investigated the association between initial Continuity of Care Index (COCI) status after diagnosis of type 2 diabetes mellitus (T2DM) and short- and long-term diabetes-related health outcomes.

METHODS

It targeted elderly patients aged 60 years and above diagnosed with T2DM and used the National Health Insurance Service Senior cohort data from 2008 to 2019. The outcome measures were diabetic avoidable hospitalization and diabetic complication incidence for a five-year period. The main independent variable was the first-year COCI status after T2DM diagnosis. Survival analyses were performed using the Cox proportional hazards model.

RESULTS

Participants with a good COCI status within the first year of being diagnosed with T2DM experienced a reduced risk of diabetes-induced avoidable hospitalization (five years: Hazard ratio (HR) 0.39, 95 % Confidence interval (CI) 0.27-0.57; overall period: HR 0.56, 95 % CI 0.43-0.72) and diabetic complications (five years: HR 0.74, 95 % CI 0.68-0.80; overall period: HR 0.77, 95 % CI 0.71-0.82).

CONCLUSIONS

In the short- and long-term, there is a need for early management and improved healthcare accessibility of diabetes to prevent diabetes-avoidable hospitalization and diabetes-related complications.

Examining the factors associated with inpatients' perception of overtreatment in Korea: a cross-sectional study

BACKGROUND

Patients' perception of receiving overtreatment can cause distrust in medical services. Unlike outpatients, inpatients are highly likely to receive many medical services without fully understanding their medical situation. This information asymmetry could prompt inpatients to perceive treatment as excessive. This study tested the hypothesis that there are systematic patterns in inpatients' perceptions of overtreatment.

METHODS

We examined determinant factors of inpatients' perception of overtreatment in a cross-sectional design that used data from the 2017 Korean Health Panel (KHP), a nationally representative survey. For sensitivity analysis, the concept of overtreatment was analyzed by dividing it into a broad meaning (any overtreatment) and a narrow meaning (strict overtreatment). We performed chi-square for descriptive statistics, and multivariate logistic regression with sampling weights employing Andersen's behavioral model.

RESULTS

There were 1,742 inpatients from the KHP data set that were included in the analysis. Among them, 347 (19.9%) reported any overtreatment and 77 (4.42%) reported strict overtreatment. Furthermore, we found that the inpatient's perception of overtreatment was associated with gender, marital status, income level, chronic disease, subjective health status, health recovery, and general tertiary hospital.

CONCLUSION

Medical institutions should understand factors that contribute to inpatients' perception of overtreatment to mitigate patients' complaints due to information asymmetry. Moreover, based on the result of this study, government agencies, such as the Health Insurance Review and Assessment Service, should create policy-based controls and evaluate overtreatment behavior of the medical providers and intervene in the miscommunication between patients and providers.

Which indicator should be used? A comparison between the incidence and intensity of catastrophic health expenditure: using difference-in-difference analysis

BACKGROUND

Catastrophic health expenditure (CHE) represents out-of-pocket payment as a share of household income. Most previous studies have focused on incidence aspects when assessing health policy effects. However, because CHE incidence is a binary variable, the effect of the health policy could not accurately be evaluated. On the contrary, the intensity of CHE is a continuous variable that can yield completely different results from previous studies. This study reassesses the coverage expansion plan for four serious diseases using the intensity of CHE in Korea.

METHODS

We used the Korea Health Panel Study from 2013 to 2015 to conduct the analysis. The study population is households with chronic diseases patients. We divided the population into two groups: the policy beneficiary group, i.e., households with a patient of any of the four serious diseases, and the non-beneficiary group. A difference-in-difference model was employed to compare the variation in the intensity and incidence of CHE between the two groups. We defined the incidence of CHE as when the ratio of out-of-pocket medical expenses to household income is more than a threshold of 10%, and the intensity of CHE is the height of the ratio subtracting the threshold 10%.

RESULTS

The increased rate of CHE intensity in households with four serious diseases was lower than that in households with other chronic diseases. The interaction term, which represents the effect of the policy, has a significant impact on the intensity but not on the incidence of CHE.

CONCLUSIONS

CHE indicators should be applied differently according to the purpose of policy evaluation. The incidence of CHE should be used as the final achievement indicator, and the intensity of CHE should be used as the process indicator. Furthermore, because CHE has an inherent characteristic that is measured by the ratio of household income to medical expenses, to lower this, a differential out-of-pocket maximum policy for each income class is more appropriate than a policy for strengthening the coverage for specific diseases.

How public and private health insurance coverage mitigates catastrophic health expenditures in Republic of Korea

Background

The private health insurance (PHI) market in Republic of Korea has instituted indemnity insurance plans that provide partial reimbursements for some medical services or costs that are not covered by the National Health Insurance (NHI). To date, no study has estimated the extent to which PHI coverage lowers the economic burden of households’ access to health care. The current study aims to evaluate the design of Korea’s PHI system in terms of coverage using a catastrophic health expenditure (CHE) indicator and compare it with NHI.

Methods

This study determined the difference between the number of households that were subscribed to PHI and those that received reimbursements from PHI. Additionally, it compared the effects of reduced CHE by NHI benefits with PHI reimbursements. Furthermore, it compared PHI reimbursements based on income class. Finally, it analyzed the contribution of NHI and PHI to CHE reduction through a two-part model with hierarchical regression.

Results

The results indicated that of the 5644 households examined, 3769 subscribed to PHI, but only 246 households received reimbursements. Notably, NHI reduced CHE incidence by 15.17%, whereas PHI only reduced CHE by 1.22%. The NHI scheme indicated reduced inequality as it provided more benefits to the low-income class for their used medical services, whereas PHI paid more reimbursements to the high-income class. Accordingly, NHI coverage has protected households from CHE and improved equality to some extent; however, PHI coverage has had a relatively low effect on relieving CHE and has increased inequality.

Conclusions

The indemnity health insurance plans of PHI companies in Korea only cover partial medical costs or services, and so, most patients do not receive reimbursements. Thus, Korea’s PHI system needs to improve to provide benefits to patients more generously and alleviate their financial burden.

Effects of Trunk Stabilization Exercises on Different Support Surfaces on the Cross-sectional Area of the Trunk Muscles and Balance Ability

[Purpose] The purpose of this study was to examine the effects on stroke patients of trunk stabilization exercise on different support surfaces. [Subjects and Methods] Sixteen stroke patients with onset of stroke six months earlier or longer were randomly and equally assigned to group I (exercise performed on a stable support surface) and group II (exercise performed on an unstable support surface). The two groups conducted the trunk stabilization exercises on the respective support surfaces, in addition to existing rehabilitation exercises five times per week for 12 weeks. Changes in the cross-sectional area (CSA) of the muscles were examined using computed tomography (CT), and changes in the balance ability were assessed using a measuring system and the trunk impairment scale (TIS). [Results] In group I, there was a significant increase in the CSA of the mulifidus muscle on the side contralateral to the brain lesion and in the paravertebral and multifidus muscles on the side ipsilateral to the brain lesion. In group II, there was a significant increase in the CSA of the paravertebral and multifidus muscles on the side contralateral to the brain lesion and on the side ipsilateral to the brain lesion. In terms of changes in balance ability, the sway path (SP) and TIS significantly improved in group I, and the SP, sway area (SA), and TIS significantly improved in group II . [Conclusion] Exercise on the unstable support surface enhanced the size of the cross-sectional area of the trunk muscles and balance ability significantly more than exercise on the stable support surface.

Jugular foramen schwannomas: surgical approaches and outcome of treatment

Twelve cases of schwannomas of the jugular foramen that involved surgery in our department between 1983 and 1997 are described. Eight were women and 4 were men (mean age, 40 years), and the duration of their symptoms, the most predominant of which were hearing loss and tinnitus, ranged from 1 month to 20 years (median, 8.5 months). Depending on their radiological and surgical features, tumors were classified as type A, a tumor primarily at the cerebellopontine angle with minimal enlargement of the jugular foramen (n = 5); type B, a tumor primarily at the jugular foramen with or without intracranial extension (n = 4); type C, a primarily extracranial tumor with extension into the jugular foramen (n = 0); or type D, a dumbbell tumor with both intracranial and extracranial components (n = 3). A retrosigmoid suboccipital craniectomy (RSSOC) was performed for type A tumors; for types B and D, the RSSOC or staged infratemporal fossa approach (ITFA)/RSSOC was used. Total removal was achieved in 6 cases, near total removal in 3, and subtotal removal in 3. The most common complication was lower cranial nerve dysfunction (n = 5). The follow-up period ranged from 6 to 173 (mean, 48) months, and there was no recurrence. Two patients showed regrowth of the tumor after subtotal resection, however. In 1 of these, the residual tumor had progressed within 12 months of initial surgery, it was again resected and linac radiosurgery was successful. In the other, the residual mass had progressed within 8 months of initial surgery, and the pathological report indicated malignant peripheral nerve sheath tumor. Conclusively, type A tumors could be totally resected with the retrosigmoid approach alone. For type B and D tumors, however, combined ITFA and retrosigmoid approach showed the better results. In spite of our limited data, cases showing adhesion to critical structures can be managed by subtotal or near total resection followed by radiosurgery to reduce postoperative complications.

A cranio-orbital-zygomatic approach to dumbbell-shaped trigeminal neurinomas using the petrous window

We applied a cranio-orbital-zygomatic approach that extends the temporal craniotomy more posteriorly and minimizes the frontal orbitotomy of an ordinary orbitozygomatic approach in order to provide wide access to the already eroded petrous apices along the long axis of trigeminal neurinomas. We treated seven dumbbell-shaped trigeminal neurinomas between 1991 and 1998 (mean follow-up, 38 months; range, 9 to 109 months). The configuration of the tumor mass was assessed on magnetic resonance imaging by measuring its long diameter in the middle and posterior fossae and the width of petrous erosion. Tumors were then classified into five types based on their distribution over the petrous ridge. Total removal was achieved in six patients, who showed no evidence of tumor recurrence during the follow-up period. The only major complication was one case of anesthesia dolorosa. The one patient with a subtotal removal developed a recurrence 12 months after surgery, in the posterior fossa. The cranioorbital-zygomatic approach could be an effective method for removing dumbbell-shaped trigeminal neurinomas, particularly in cases of wide petrous erosion from the tumor. If, however, the tumor has a larger posterior fossa component, this approach may not provide adequate exposure to achieve a total resection.

Characterization of Tobacco mosaic virus Isolated from Potato Showing Yellow Leaf Mosaic and Stunting Symptoms in Korea

Four isolates of Tobacco mosaic virus (TMV-potato 1 to 4) were obtained from potato plants (Solanum tuberosum) in cultivated potato plantings in Korea. These isolates were differentiated based on biological properties, symptomatology, and nucleotide sequence analysis of the coat protein (CP) gene. TMV potato isolates caused typical symptoms on 20 inoculated plant species as compared to the type (U1) TMV strain. The four isolates each produced distinctly different symptoms on Gomphrena globosa. In contrast to the type strain of TMV, infections with two of the isolates reported here were not restricted to inoculated leaves of G. globosa but moved systemically through the plants. In addition, three additional systemic hosts (Chenopodium amaranticolor, C. quinoa, and C. murale) for TMV were revealed. Sequence analysis of the CP gene differentiated TMV-potato isolates. The CP gene sequence exhibited significant identity (83.1 to 99.2%) among TMV-potato isolates while showing 88.1 to 99.4% identities on predicted amino acid sequences. Based on a comparison of the CP gene nucleotide and deduced amino acid sequences between TMV-potato isolates and other TMV strains, TMV-potato 1, 3, and 4 were closely related to TMV strains U1, U2, V-FAVA, and NC82 with 98.8 to 100% identity. In contrast, TMV-potato 2 was closely related to TMV strains L, KP, KO-TOB, K1, and K2 with 93.8 to 98.8% identity.

Biological behavior and tumorigenesis of subependymal giant cell astrocytomas

In spite of the benign nature of subependymal giant cell astrocytomas (SEGAs), some show massive hemorrhage, rapid growth, and tumor recurrence. This led us to investigate the biological behavior, cell dynamics, and tumorigenesis of SEGAs. All patients (4 men and 3 women; age range, 6-27 years; mean, 13.6 years) had features of tuberous sclerosis complex and obstructive hydrocephalus. One patient had intratumoral bleeding. In two patients, sequential neuroimaging showed a subependymal nodule growing to become a SEGA. All underwent surgical resection without radiation therapy. One tumor recurred and was treated surgically. There were no postoperative deaths. The presence of cytologic atypia, mitoses and vascular proliferation had no implication in terms of the clinical course. MIB-1 labeling indices were low (mean, 0.9), indicating low proliferative potential. Unexpectedly, bcl-2 staining was sparse and bax staining predominated in majority of cases. However, the mean value of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling index was low. Immunohistochemically, tumors were positive for both glial and neuronal markers. In the majority of our cases, the expression of p53 was low. Only one tumor was focally positive for tuberin. SEGAs have low proliferative potential and apoptotic activity, and exhibit features of mixed glial-neuronal differentiation. In contrast to p53, tuberin is suggested to be the tumor suppressor in this tumor.

Postoperative spinal seeding of craniopharyngioma. Case report

The authors present a case of postoperative spinal seeding of papillary craniopharyngioma. This 27-year-old man who had previously undergone subtotal removal of a suprasellar craniopharyngioma was admitted because of low-back and right leg pain. Results of neurological examination showed a limitation in straight-leg raising in the right side with no sensorimotor changes. Magnetic resonance imaging of the lumbar spine demonstrated multiple enhanced intradural extramedullary masses causing spinal cord compression. Pathological examination of the tumor tissue obtained via laminectomy revealed papillary craniopharyngioma, which had the same histological features as those of the previous suprasellar tumor. Several ectopic recurrences of craniopharyngioma have been reported; however, the authors believe that this is the first published report of the spinal seeding of craniopharyngioma.

Prevalence of Gs alpha mutations in Korean patients with pituitary adenomas

The reported frequencies of Gs alpha mutations (gsp mutations) in growth hormone (GH)-secreting pituitary adenomas are variable (ranging from 4.4 to 43%), and the presence of these mutations in the other pituitary adenomas is still a matter of controversy. Previous clinical and biochemical analyses of patients with GH-secreting pituitary adenomas and gsp mutations produced conflicting results and did not demonstrate obvious characteristics. Therefore, we investigated the prevalence of gsp mutations in Korean patients with pituitary adenomas and elucidated the characteristics of these patients. Forty-four GH-secreting adenomas, 7 prolactin (PRL)-secreting adenomas and 32 clinically non-functioning adenomas were examined for the presence of point mutations in codon 201 and 227 of the Gs alpha gene using a nested PCR and direct sequencing of DNA extracted from fresh tissue or paraffin-embedded pituitary adenoma samples. Seven of the 44 GH-secreting pituitary adenomas had point mutations at codon 201 or 227; of these, five mutations were in codon 201 and two were in codon 227. In patients with gsp mutations, mean tumor size was significantly smaller than in patients without gsp mutations (15.9+/-8.7 mm vs. 24.9+/-14.9 mm, P<0.05). Age, sex, basal GH levels, GH response to oral glucose loading, GH response to octreotide and surgical outcome were not different in the two groups. One of the 32 clinically non-functioning pituitary adenomas had a point mutation at codon 201; none of the seven prolactinomas had these mutations. These results show that gsp mutations are not rare in Korean acromegalic patients and mean tumor size is significantly smaller in acromegalic patients with gsp mutations. Our results also confirm the low frequency of gsp mutations in clinically non-functioning pituitary adenomas and the absence of gsp mutations in prolactinoma.

Chordoid meningioma with polyclonal gammopathy. Case report

The authors present a case of chordoid meningioma in a 55-year-old woman who manifested headache and personality change. Magnetic resonance imaging of the brain and cerebral angiography demonstrated a mass in the right frontal lobe that resembled a typical convexity meningioma. However, the pathological diagnosis was chordoid meningioma, a rare subtype of this tumor that usually occurs in adolescence and is known to be associated with Castleman syndrome. A meningothelial meningiomatous pattern suggestive of a meningothelial origin was focally present, and cytokeratin-positive squamoid cells were noted in the tumor. The lesion lacked dense infiltration of lymphocytes and plasma cells. Polyclonal gammopathy was the only sign of Castleman syndrome and hypochromic microcytic anemia was absent in this case. Polyclonal gammopathy resolved completely 6 months after total removal of the mass.

Pepper gene encoding a basic beta-1,3-glucanase is differentially expressed in pepper tissues upon pathogen infection and ethephon or methyl jasmonate treatment

A basic beta-1,3-glucanase cDNA clone (CABGLU) was isolated from the cDNA library constructed from hypersensitive response lesions of pepper leaves infected with avirulent strain of Xanthomonas campestris pv. vesicatoria. The deduced polypeptide of CABGLU which contains a C-terminal extension N-glycosylated at a single site characterized as typical structure of class I beta-1,3-glucanase has a high level of identity with tobacco basic beta-1,3-glucanase (77.4%), but only a moderate level of identity with tomato acidic beta-1,3-glucanase (42.6%). Genomic DNA gel blot analysis indicates that the pepper genome contains one or two beta-1,3-glucanase copy genes. Transcripts of the CABGLU gene were more induced in incompatible interactions than in compatible interactions, when inoculated with X. campestris pv. vesicatoria or Phytophthora capsici. Accumulation of CABGLU mRNA was strongly induced in pepper leaves by both ethephon and methyl jasmonate. The CABGLU mRNA was constitutively expressed only in the roots of all the plant organs. These data indicate that the basic beta-1,3-glucanase gene may be induced by pathogen attack and abiotic stresses.

Pepper gene encoding a basic class II chitinase is inducible by pathogen and ethephon

A chitinase cDNA clone (designated CAChi2) was isolated from the cDNA library of pepper leaves infected with Xanthomonas campestris pv. vesicatoria. The 1004-bp full-length CAChi2 cDNA encodes a basic chitinase with an N-terminal 24 amino acid signal peptide followed by a catalytic region. An analysis of its sequence indicates that CAChi2 is a class II chitinase, because it does not have chitin-binding domain and C-terminal extension sequences. The deduced amino acid sequence of CAChi2 has a high level of identity with class II chitinases from potato, tomato, tobacco and petunia. Southern analysis demonstrated that the CAChi2 chitinase is encoded by a single or two copy genes in the pepper genome. Following X. campestris pv. vesicatoria or Phytophthora capsici infection, the CAChi2 chitinase mRNA was more highly expressed in the incompatible interaction, compared to expression in the compatible interaction. Treatment with ethylene-releasing ethephon resulted in a strong accumulation of the transcripts in the leaves. In contrast, DL-beta-amino-n-butyric acid, salicylic acid and methyl jasmonate were not effective in inducing CAChi2 transcripts in pepper leaves.

Meningioma manifesting intracerebral haemorrhage: a possible mechanism of haemorrhage

We present a possible mechanism of intracerebral peritumoural haemorrhage in meningioma based on the clinical data of three of our cases. A meningioma manifesting intracerebral haemorrhage is uncommon and some sporadic case reports have been presented, but without any proven mechanisms. We are presenting three cases of convexity meningioma manifesting spontaneous intracerebral haemorrhage with apoplectiform onset. All three patients had no evidence of bleeding tendency or other predisposing factors for haemorrhage. Preoperative radiological studies showed a solid mass attached to the dura with intracerebral peritumoural haematoma. Total removal of the tumour and haematoma could be achieved in every case. Histological investigation revealed extensive tumour infarction in two cases and fibrosis related to pre-existing ischaemia in the other case. The diagnoses were atypical meningioma in two cases and transitional type in one case. We suggest that extensive tumour infarction might be a cause of spontaneous intracerebral peritumoural haemorrhage in our series of patients.

Effects of clarithromycin on rheological properties of nasal mucus in patients with chronic sinusitis

Macrolide antibiotics have a variety of actions along with antimicrobial action. To determine the effects of oral administration of clarithromycin (CAM) on rheological properties, we measured the spinability, dynamic viscoelasticity, and solid composition of human nasal mucus from 18 patients with chronic sinusitis before and after administration of CAM for 4 weeks. After administration of CAM, the spinability and percent solid composition of nasal mucus increased from 26.5 +/- 12.2 mm to 40.2 +/- 18.7 mm and 7.86% +/- 3.47% to 13.90% +/- 3.67% (p < .05), respectively, whereas the ratio of the viscosity to the elasticity (eta'/G') of nasal mucus after the administration of CAM decreased in all of the mucus samples. These results suggest that treatment with CAM may modulate the rheological properties of nasal mucus in patients with chronic sinusitis.

Long-term outcome and growth rate of subtotally resected petroclival meningiomas: experience with 38 cases

OBJECTIVE

To evaluate the long-term outcome of a subtotally resected residual tumor and to assess its growth rate, we analyzed the records of 38 patients with residual petroclival meningioma.

METHODS

Clinical records and radiological findings of 38 cases of petroclival meningioma that were diagnosed and subtotally resected at Seoul National University Hospital between 1981 and 1997 were carefully reviewed. Follow-up imaging studies were reviewed, and Karnofsky performance scale scores at the last follow-up were recorded. The duration of follow-up ranged from 6 to 141 months (mean, 47.5 mo; median, 30 mo). Tumor progression and progression-free survival rates were assessed. The growth rate of a residual tumor was evaluated by measuring the equivalent diameter and the tumor volume serially; the tumor doubling time was calculated, and the predictive factors for determining the growth pattern in residual tumors and the prognosis were analyzed.

RESULTS

In 33 (87%) of the 38 patients, Karnofsky performance scale scores at the last follow-up were 80 or above. The median progression-free survival time among patients with subtotally resected tumors was 66 months, and the 5-year progression-free survival rate was 60%. The growth rate of residual tumors was low (volume increase, 4.94 cc/yr; diameter increase, 0.37 cm/yr). The mean tumor doubling time was 8 years. Although there were no significant predictive factors, age and extent of tumor resection seemed to influence the progression-free survival rate. Significant factors affecting the growth rate were age and occurrence of menopause.

CONCLUSION

Subtotal resection with or without radiation or radiosurgery should be considered as a suitable treatment option for patients with petroclival meningiomas, especially the elderly, because the growth rate of residual tumors is low.

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.

MR findings of desmoplastic fibroma of the spine. A case report

We report on the MR imaging findings in a case of spinal desmoplastic fibroma (DF). DF of the bone is a rare, locally aggressive tumor. It is commonly located in long bones, pelvis or mandible. DF involving the spine is extremely rare and difficult to distinguish from other bony lesions such as giant cell tumor, chordoma and fibrous dysplasia of the spine. This case of DF of the spine showed MR findings similar to those of DF arising in the metaphysis of a long bone.

Isolation, partial sequencing, and expression of pathogenesis-related cDNA genes from pepper leaves infected by Xanthomonas campestris pv. vesicatoria

Specific cDNAs showing differential expression in bacteria-infected pepper leaves as opposed to healthy leaves were isolated from a pepper cDNA library from hypersensitive response (HR) lesions of leaves infected with an avirulent strain of Xanthomonas campestris pv. vesicatoria. Among a total of 282 cDNA clones tested, 36 individual cDNA genes (13%) hybridized strongly or differentially to the cDNA probes from bacteria-infected leaves. Ten Capsicum Annuum-Induced (CAI) genes encoding putative thionin, lipid transfer protein I and II, osmotin (PR-5), class I chitinase, beta-1,3-glucanase, SAR 8.2, stellacyanin, leucine-rich repeat protein, and auxin-repressed protein were identified. Two CAI genes showed little or no sequence homology to the previously sequenced plant genes. Transcripts of the CAI genes were strongly or preferentially induced in pepper tissues by infection with X. campestris pv. vesicatoria or Phytophthora capsici, and by abiotic elicitor treatment. In particular, most of the CAI genes were strongly induced in pepper tissues by ethephon and methyl jasmonate.

Neurenteric cyst: its various presentations

Neurenteric (NE) cyst is an uncommon developmental lesion lined with epithelium of endodermal origin. To investigate the clinical manifestation and response to surgery, we retrospectively analyzed eight cases of NE cyst that has been confirmed by surgery. Four were in children. The duration of follow-up ranged from 2 to 105 (mean 38) months. One cyst was in the ventral portion of the posterior cranial fossa and the other seven were on the spinal cord. The chief complaints were motor weakness (5), pain (2), and voiding difficulty (1). In one child and three adults, the duration of symptoms was more than 3 years. Children tended to show rapid progression and excellent recovery after surgery. Although total removal of cyst was possible only in two cases, there was no recurrence. The presentation of an NE cyst may be insidious. Clinical suspicion is important for an early diagnosis and better outcome. Because of the benign course after subtotal excision, too-aggressive removal of the lesion should be avoided.

Gliomatosis cerebri: clinical features, treatment, and prognosis

To clarify clinical features and to elucidate prognostic factors and prognosis, the authors retrospectively analyzed 16 cases of gliomatosis cerebri treated at Seoul National University Hospital between January 1988 and December 1995. Age at diagnosis ranged from 19 to 62 (median 34) years and male to female ratio was 10:6. Most presented with headache or seizure, and the mean duration of symptoms was 12.8 months. A poorly defined diffuse high signal intensity lesion, extending in T2-weighted images for two lobes or more, was the characteristic magnetic resonance (MR) image finding. On postcontrast T1-weighted MR imaging, focal enhancement of the lesion was detected in five cases. All patients underwent histological confirmation by craniotomy (9 cases) or stereotactic biopsy (7 cases). Histologically, all patients had compatible findings of gliomatosis cerebri which are the widespread infiltration of neoplastic glial cells with minimal destruction of pre-existing structures. After histological diagnosis, external radiation therapy was begun except in one case, who declined this treatment. Fourteen patients completed the whole procedure and received the planned dose (mean 5780 cGy). Median survival time after diagnosis was 38.4 months. In univariate analysis, the Ki-67 labelling index (> 1) showed significant correlation with the length of survival (p = 0.006). It is suggested that 1) gliomatosis cerebri can be diagnosed by a combination of MR imaging findings and histological examination; 2) histological diagnosis and external radiation therapy might be a good treatment modality; 3) the Ki-67 labelling index correlates significantly with survival time.

Whole-body [18F]FDG PET in the management of metastatic brain tumours

BACKGROUND

To determine its roles in the diagnosis and the systemic evaluation of metastatic brain tumours, whole-body positron emission tomography (PET) using [18F]FDG was performed in 20 consecutive patients.

METHODS

All patients were thought to be suffering or needing to be differentiated from metastatic brain tumours. Nine patients had multiple brain lesions; six were older and showed a rim-enhancing lesion with surrounding oedema; seven had homogeneously enhancing periventricular lesion(s) on computed tomography (CT) and/or magnetic resonance (MR) imaging, thought to be central nervous system lymphomas. Two patients had skull mass(es) and two patients had a solid mass suspected to be, respectively, a haemorrhagic metastasis and a metastatic malignant melanoma. All of them received whole-body [18F]FDG PET and conventional systemic work-up for metastasis in order to compare the results of the two methods.

RESULTS

Metastatic brain tumours were diagnosed on whole-body [18F]FDG PET in eleven patients who had extracranial and intracranial hypermetabolic lesions. In nine of these, a conventional work-up also detected primary lesions which on whole-body [18F]FDG PET were seen to be hypermetabolic foci. Systemic lymph node metastases were detected by whole-body [18F]FDG PET only in two patients and histological diagnosis was possible by biopsy of lymph nodes rather than of brain lesions. In the remaining nine patients who had only intracranial hypermetabolic foci, histological diagnosis was made by craniotomy or stereotactic biopsy. It was confirmed that seven of nine patients were suffering from a primary brain tumour and two from metastatic carcinoma. None of the nine showed evidence of systemic cancer on conventional work-up. Histological diagnoses of the primary brain tumours were four cases of primary central nervous system lymphoma and one each of multifocal glioblastoma, Ewing's sarcoma, and cavernous angioma. Patients felt no discomfort during the whole-body [18F]FDG PET procedure and there were no complications. The false negative rate in [18F]FDG PET and in conventional work-up was 15.4% and 30.7% respectively. There were no false positives on either [18F]FDG PET or conventional work-up.

CONCLUSION

It is suggested that whole-body [18F]FDG PET is a safe, reliable, and convenient method for the diagnosis and systemic evaluation of patients thought to be suffering or needing to be differentiated from a metastatic brain tumour.

Effects of Ginkgo biloba extract on the cochlear damage induced by local gentamicin installation in guinea pigs

Investigations evaluating the protective effect of Ginkgo biloba extract (EGb) on gentamicin (GM) ototoxicity were undertaken. Guinea pigs treated with 5 mg/kg gentamicin sulfate on the round window niche (RWN) showed acute changes on electrocochleogram and hair cell or microvilli damage on scanning electron microscopy (SEM). There was accumulation of GM in the whole cochlea, especially in the organ of Corti, stria vascularis, and type III fibrocyte on immunohistochemical study. However, the guinea pigs pretreated with local or systemic EGb revealed no significant changes by local GM installation. From these results, we concluded that EGb has a protective effect on the development of GM ototoxicity in the cochlea.

Pediatric pineal tumors: need for a direct surgical approach and complications of the occipital transtentorial approach

In an investigation of the benefits and risks of direct surgical approaches to pediatric pineal tumors, the need for such approaches, the feasibility of surgical removal and operative complications were evaluated in 25 histologically proven cases. Five tumors were germinomas (GEs) or GE-predominant mixed germ cell tumors (GCTs), in which stereotactic biopsy can be adequate. Twenty of the 25 pineal tumors (80%) were teratomas (TEs), TE-predominant mixed GCTs or other tumors that need direct surgical approaches. Among the 21 tumors resected by the occipital transtentorial (OTT) approach, 13 were removed radically (>95%) and 6 others, subtotally (>75%). Complications of using the OTT approach included homonymous hemianopsia (7), Parinaud's syndrome (6), other eyeball movement limitation (7), seizure (5), and new hydrocephalus (3). The majority of these were transient, resolving within a few days or months, or easily controlled. The results showed that 80% of pediatric pineal tumors needed direct surgical approaches and that the majority were successfully removed by OTT surgery with an acceptable level of risk.

In vivo single-voxel proton MR spectroscopy in intracranial cystic masses

PURPOSE

Our objective was to evaluate the proton MR spectroscopic pattern of the cystic contents of various intracranial masses and to report characteristic spectral patterns that may be helpful in the differential diagnosis of these lesions.

METHODS

We evaluated 40 proton MR spectra obtained from cystic contents of various intracranial cystic masses in 39 patients, including gliomas (n = 14), metastases (n = 3), abscesses (n = 8), cysticercosis (n = 4), epidermoids (n = 3), and others (n = 7). Proton MR spectroscopy was performed on a 1.5-T MR unit using a point-resolved spectroscopic sequence with a 2 x 2 x 2 cm3 volume of interest. Assignment of the resonance peaks was based on previous studies.

RESULTS

Adequate proton MR spectroscopic data were obtained in 35 cases (88%). In most gliomas and metastases, only a lactate resonance was observed. There was a trend toward a higher lactate peak in high-grade gliomas. A few tumors, including malignant gliomas and metastases, showed lipid signal combined with lactate signal. In abscesses, there were various combinations of lactate, acetate, succinate, amino acids (including valine, alanine, and/or leucine), and/or unassigned resonances. In cysticercosis, resonances of lactate, succinate, alanine, acetate, and/or unassigned resonances were observed. Three epidermoid cysts showed only lactate signal. There were no identifiable resonances from the arachnoid and porencephalic cysts.

CONCLUSION

Only lactate is commonly observed in a variety of intracranial cystic masses, except for abscess and cysticercosis, in which resonances of acetate, succinate, amino acids, and/or unassigned metabolites can be seen in addition to a lactate peak.

Pineal tumors: experience with 48 cases over 10 years

The authors retrospectively reviewed 48 patients treated at Seoul National University Hospital (SNUH) between 1986 and 1995. There were 35 children and 13 adults, accounting for 10.1% of 345 pediatric and 0.68% of 1914 adult brain tumors in SNUH during the same period. The 48 cases consisted of 33 cases of germ cell tumor (69%, GCT); 6 of pineoblastoma (PB, 12.5%); 3 of pineocytoma (PC, 6.3%); 3 of anaplastic astrocytoma (6.3%); 1 of astrocytoma; 1 of glioblastoma; and 1 of ependymoma. The median age was 13 years (range 1-59) and the male-to-female ratio was 3.36:1. The most frequent presenting symptom was due to increased intracranial pressure (90%), followed by Parinaud syndrome or diplopia (50%). Patients with a benign tumor, such as teratoma (TE), astrocytoma, or ependymoma, underwent surgery by the occipital transtentorial approach (OTT) for attempted radical resection without adjuvant therapy, while patients with immature teratoma (imTE), PC, and anaplastic astrocytoma underwent regional radiotherapy (RT) after debulking via OTT. Seven patients with nongerminomatous malignant GCT (NG-MGCT) and 3 with germinoma (GE) underwent craniospinal radiation only, 6 with GE, a NG-MGCT, and 2 with GE+TE received craniospinal radiotherapy (CSRT) after debulking via OTT. Three patients with GE, 4 with NG-MGCT, and 3 with PB underwent radiochemotherapy after debulking via OTT. Forty-four patients were followed up after treatment. The median follow-up period was 36 months. All patients with GE were alive after RT at 36 months (median) of follow-up (range 7-70 months). All with GE+TE and TE were alive. Three patients with PC or astrocytoma were also alive with stable or no evidence of disease. In 1 of the 3 cases of imTE there was a recurrence. However, 4 patients with NG-MGCT died, all of whom had undergone CSRT only; 2 PB patients were alive (12, 19 months), 1 in a moribund status (36 months), and 2 were dead (6, 60 months). The overall mean survival time with pineal tumors was 66 months and the 3-year survival rate was 84% with minimal posttreatment complications. It is concluded that pineal region tumors have male and childhood predominances, and the most common tumor is GCT. The majority of pineal region tumors are malignant. Pineal region tumors can be approached safely and effectively and the surgical complications are mostly transient. Their prognosis is dependent on the pathologies and treatment modalities.

Central neurocytoma: the role of radiation therapy and long term outcome

BACKGROUND

It has been suggested that the biologic behavior of central neurocytoma is indolent, although little is known regarding the role of radiation therapy and long term outcome. To clarify the role of radiation therapy and long term outcome, the authors retrospectively analyzed 15 cases of central neurocytoma.

METHODS

Clinical records and radiologic findings of 15 cases of central neurocytoma diagnosed at Seoul National University Hospital between January 1982 and February 1995 were carefully reviewed. The duration of follow-up was from 18-168 months (mean, 52 months); follow-up images were reviewed and the patient's Karnofsky performance scale (KPS) was assessed up to the time of last follow-up.

RESULTS

The age of the patients ranged from 15 to 60 years (mean, 25 years) and the male to female ratio was 11:4. Macroscopic total resection of the tumor was performed in seven patients, two of whom received fractionated radiation therapy. Subtotal removal of the tumor was performed in eight patients, five of whom received this same therapy. In 2 of the 5 patients who did not receive radiation therapy after macroscopic total resection, the tumors recurred 8 and 21 months after surgery, respectively; in contrast, recurrence was not detected in the 2 patients who received fractionated radiation therapy after macroscopic total resection. In all five patients who received fractionated radiation therapy after subtotal resection, the tumor shrank (n = 3) or disappeared (n = 2) during the postsurgical follow-up period ranging from 27-113 months; the tumor began to shrink from 6 months to 2 years after radiation. No change was found in the three patients who did not receive radiation therapy after subtotal resection. At the time of last follow-up, the KPS was greater than 90 in all patients except one who required assistance in his daily activities because of complications from radiation therapy.

CONCLUSIONS

It is suggested that even if the biologic behavior of a central neurocytoma is benign, radiation therapy appears to have an effect on tumor control. However, it should be carefully decided whether to use radiation therapy for a residual tumor because radiation can cause delayed complications and the clinical course of subtotally resected patients who do not receive radiation therapy is extremely benign.

Prevalence and risk factors for perennial allergic rhinitis in Korea: results of a nationwide survey

A nationwide survey on the prevalence and risk factors for perennial allergic rhinitis in Korea was conducted by means of physical examination by otolaryngologists from July to October 1991. The total number of subjects examined was 9069 and they were drawn from 2899 households in 60 different districts throughout the country. The overall prevalence of perennial allergic rhinitis was 1.14%. For the evaluation of risk factors for perennial allergic rhinitis, a case-control analysis was carried out. The prevalence was influenced by age and urban or rural province. Risk factors such as current urban residence, urban birth place, overcrowding, higher educational attainment, nasal septal deformity and chronic sinusitis with nasal polyposis, indicated an increased risk of perennial allergic rhinitis. Other factors such as smoking and personal factors showed little influence on prevalence.

Cerebral sparganosis: clinical manifestations, treatment, and outcome

Cerebral sparganosis is a rare parasitic disease caused by infestation by the plerocercoid larva of Spirometra mansoni. The authors retrospectively analyzed 17 cases of cerebral sparganosis treated at Seoul National University Hospital between 1986 and 1994. The patients' ages at diagnosis ranged from 6 to 57 years (median 32 years) and the male/female ratio was 13:4. Diagnosis was based on radiological findings, serological test results, operative findings, and histopathological examinations. Characteristic magnetic resonance (MR) findings consisted of widespread white matter degeneration and cortical atrophy, mixed-signal lesion (low in the central and high in the peripheral regions on T2-weighted images) with irregular dense enhancement of central foci and changes in the location and shape of the enhancing lesion in follow-up studies. Ten patients underwent surgical removal of the parasitic lesion, six received medical treatment alone (five with praziquantel and one with antiepileptic drugs), and one underwent insertion of a ventriculoperitoneal shunt and a course of praziquantel. Follow-up periods ranged from 13 to 111 months (mean 49 months). Seven patients who underwent complete removal of the lesion, live worm, or degenerative worm with surrounding granuloma showed a favorable course. Patients who received medical treatment alone or incomplete removal exhibited progression in their neurological deficits and their seizures could not be controlled. Medication with praziquantel seemed to have no killing effect on live worms. The authors conclude that MR imaging is the most valuable modality for the early detection of cerebral sparganosis and that complete surgical removal of granuloma together with worms, whether they are alive or degenerative, is the treatment of choice.

Prevalence and risk factors of chronic sinusitis in Korea: results of a nationwide survey

From July through October 1991, a nationwide survey was conducted on the prevalence and risk factors of chronic sinusitis in Korea, using medical and family histories as well as physical examination. In all, 9,069 subjects were examined from 2,899 households residing in 60 different areas throughout the country. The overall prevalence of sinusitis was 1.01%. Casecontrol analysis was performed to determine possible risk factors for sinusitis. No significant differences were found in age groups or sexes. A significant geographic difference was seen in prevalence in the different provinces studied. Economic activity, crowding and allergy were significant risk factors. Other factors such as urban or rural residence, birth place, maternal and paternal age at birth, marriage, smoking history, education, social class, prior trauma, height and weight, and nasal septal deformities did not correlate with the occurrence of sinusitis.

Central neurocytoma: proliferative potential and biological behavior

The authors analyzed 13 central neurocytomas diagnosed at Seoul National University Hospital between January 1982 and December 1993 to clarify the proliferative potential and biological behavior of these tumors. The tumor was confined to the lateral and third ventricles in 12 cases and in one case extended from the posterior thalamus to the body and trigone area of the lateral ventricle. In all 13 cases, typical clinical and radiological findings were observed, and histological diagnosis was performed via craniotomy. The diagnosis was made using light microscopic examination, immunohistochemical staining for neuronal markers, and electron microscopic findings of neuronal differentiation. One patient died due to tumor progression with recurrence 26 months after subtotal removal plus radiation therapy. Another patient had a recurrence 18 months after total tumor removal. The remaining 11 patients are free of recurrent tumor after a follow-up period that ranged from 14 to 109 months (median 50 months). To predict the proliferative potential, immunoreactivity to proliferating cell nuclear antigen (PCNA), silver colloid staining for nucleolar organizing regions (AgNORs), and DNA flow cytometry were performed in 10 of the 13 cases. The proportion of PCNA-positive cells was less than 1% in all cases and the AgNORs score ranged from 1.11 to 2.0 (mean 1.67). The DNA flow cytometry revealed diploidy in all cases and the calculated proliferation index ranged from 5.1% to 9.6% (mean 7.8%). The one case of tumor recurrence, in which the authors performed the study of proliferative potential, and another case that demonstrated mild nuclear pleomorphism also showed low percentages of PCNA-positive cells, low AgNORs scores, and diploidy in DNA flow cytometry. It is suggested that most central neurocytomas follow a benign clinical course with low proliferative potential assessed by PCNA, AgNORs, and DNA flow cytometry; however, recurrence is possible within a relatively short time period.

Primary central nervous system lymphoma: variety of clinical manifestations and survival

A retrospective analysis of 23 non-immune compromised patients with primary central nervous system lymphoma (PCNSL) is reported. The patients consist of 14 males and 9 females and the median age is 50 years. Most patients presented with focal neurological deficits or symptoms of increased intracranial pressure (ICP) due to mass effects around the periventricular area. However, there were four cases of diffuse type, one case of intramedullary tumour, and four cases with rapid disease progression. All the patients underwent histological confirmation by craniotomy (16 cases) or stereotactic biopsy (7 cases). The radiation therapy started after histological diagnosis in all and 6 cases received additional chemotherapy. The median survival after diagnosis of overall patients was 23 months. Six patients are in disease free status at a mean of 35 months follow-up. The uni- and multi-variative risk analysis revealed five favourable factors on survival: (1) age less than 60 years (0.05 < p < 0.1); (2)pre-operative Karnofsky performance scale (KPS) > or = 70 (p < 0.05); (3) symptom duration over four weeks (p < 0.05); (4) radiation dosage > or = 5500 cGy (p < 0.05); (5)absence of malignant cells in cerebrospinal fluid (CSF) (p < 0.05). The most frequent site of recurrence was the local area as shown in seven cases out of 11 recurrent cases. But six patients had diffuse recurrence (4 cases), systemic recurrence (2 cases), and drop metastasis (1 case). Although the recurred PCNSL had rapid progression and a grave prognosis, aggressive treatment prolonged the postrecurrence survival time significantly. Our experience suggests that 1) there are various clinical and radiological presentations and progressions of the disease; 2) treatment method should be decided along with the clinical presentation, progression of disease, and prognostic factors; 3) early diagnosis and early detection of recurrence enable the start of definitive treatment when the medical condition is still satisfactory.

Contrast-enhanced MR angiography for the diagnosis of intracranial vascular disease: optimal dose of gadopentetate dimeglumine

OBJECTIVE

Although contrast-enhanced MR angiography has been shown useful in evaluating intracranial vascular lesions, particularly those with slow flow, the optimal dose of contrast material has not been found. Accordingly, we performed a study to determine the optimal dose of gadopentetate dimeglumine for contrast-enhanced MR angiography of intracranial vascular diseases.

SUBJECTS AND METHODS

In this prospective study, 152 consecutive adult patients suspected of having intracranial vascular diseases had cerebral MR angiograms. Images were obtained with a three-dimensional time-of-flight sequence with magnetization transfer saturation on a 1.5-T unit. Imaging parameters (43/8 [TR/TE], 20 degrees flip angle, 64 1-mm-thick sections) were identical in each MR angiogram. One hundred twenty-two of 152 patients were randomly assigned to receive one of four doses (0, 5, 10, or 20 ml) of gadopentetate dimeglumine for MR angiography (36, 37, 38, and 11 patients, respectively). In patients who had normal major cerebral arteries on MR angiograms, degree and extent of visualization of the cerebral veins and small intracranial arteries were rated blindly on a three-point scale, and the results were compared among the four groups given different doses of contrast material. In another 30 patients who had unenhanced and enhanced MR angiograms, the presence or absence of artifactual narrowing of the internal carotid artery or major cerebral arteries (caused by signal loss due to slow or turbulent flow seen only on unenhanced images) and the visibility of arteriovenous malformation were determined.

RESULTS

In nearly all patients, regardless of the dose of contrast material, the cerebral veins were well visualized on MR images. Degree and extent of visualization of the cerebral veins appeared to depend on the dose of contrast material. In the 20-ml injection group, venous overlap limited interpretation of the small and large arteries, whereas in the 5- and 10-ml groups, the signal intensity of the veins was much less intense, causing no difficulty in interpretation. However, no significant differences in visibility of the small arteries were apparent between the unenhanced and enhanced MR angiograms, even though the small vessels were better visualized in some patients who received either 5 or 10 ml of contrast material. In six of the 30 patients who had both unenhanced and enhanced MR angiograms, the unenhanced images showed artifactual narrowing of the internal carotid or middle cerebral arteries, which proved to be normal on contrast-enhanced MR angiograms. Venous sinuses or draining veins were better delineated on contrast-enhanced MR angiograms in all six patients with arteriovenous malformation.

CONCLUSION

Five to 10 milliliters of gadopentetate dimeglumine appears to be an optimal dose range for contrast-enhanced cerebral MR angiography. Use of this dose can help in differentiating true stenosis of large arteries from artifactual narrowing and in depicting small arteriovenous malformation with slow flow.

Prevalence study of nasal septal deformities in Korea: results of a nation-wide survey

A nation-wide survey investigating the prevalence and risks of nasal septal deformity (NSD) was conducted by a group of otolaryngologists from July through October 1991. The total number of subjects surveyed was 9,284, and these were drawn from 2,899 households residing in 60 different areas throughout the country. The overall prevalence of NSD was 22.38%, and NSD tended to predominate in males and to increase with age. According to Mladina's classification, the most common type was type 1, followed by types 2, 3, 5, 7, 4, and 6. A positive correlation between nasal trauma history (NTH) and NSD was statistically confirmed (p < 0.01).

Cell behaviour on polymer surfaces with different functional groups

Surfaces with differently chargeable functional groups were prepared on low density polyethylene sheets by corona discharge treatment, followed by graft copolymerization of acrylic acid (-COOH, negatively chargeable) and a subsequent substitution reaction of carboxylic acid groups to hydroxyl (-CH2OH, neutral) or amide (-CONH2, neutral) groups. The amide groups grafted on the surface were further converted to amine groups (-CH2NH2, positively chargeable). The prepared surfaces were characterized by measuring the water contact angle, electron spectroscopy for chemical analysis and Fourier-transform infrared spectroscopy in the attenuated total reflectance mode. It was observed that the wettability of the different functional group-grafted surfaces largely increases compared with the control surface but is not much affected by the kind of functional groups grafted. The interaction of Chinese hamster ovary cells with the functional group-grafted surfaces was investigated. The cells adhered and grown on the surfaces were counted using an electronic cell counter and observed by a scanning electron microscope. The surface grafted with amine groups was best for cell adhesion, spreading and growth probably owing to the positively chargeable character in aqueous cell culture medium. For surfaces grafted with neutral functional groups, the surface grafted with hydroxyl groups showed better cell spreading than that grafted with amide groups.

The effect of ostial opening on experimental maxillary sinusitis in rabbits

Obstruction of the natural ostium is known to be one of the major factors in the pathogenesis of maxillary sinusitis. To explore the therapeutic effect of ostial patency, sinusitis was induced in 32 rabbits by obstruction of the natural ostium and inocculation of Streptococcus pneumoniae. They were divided into two groups: the first ("open") group included 16 rabbits with experimentally induced sinusitis, from which bone chips for obstruction of the natural ostium were removed after a period of 5 days, and the second ("closed") group included 16 rabbits with continuous obstruction of the natural ostium. The induction of sinusitis was found to be successful in all cases, when examined after five days. The amount of nasal and sinus secretion as well as histopathological findings of the sinus mucosa were investigated with light microscopy, scanning and transmission electron microscopy, two and four weeks after induction of sinusitis. The findings were significantly improved in the "open" group.

Prevalence and risk factors of chronic otitis media in Korea: results of a nation-wide survey

A nation-wide survey on the prevalence and risk factors of chronic otitis media (COM) in Korea was conducted by means of physical examination by otolaryngologists from July to October, 1991. Total subjects examined were 9,321, who were drawn from 2,899 households residing in 60 different areas throughout the country. The overall prevalence rate of OM was 2.85% whereas that of COM was 2.19%. For the study of risk factors of COM, a case-control analysis was made. The prevalence of chronic OM did not vary by sex, nor by urban-rural difference. However, the risk increased with aging. There was a significant geographic variation by provinces. General risk factors such as crowding, economic activity, childhood home, marital status, maternal or paternal age, body weight, smoking habits, age of first otorrhea, preauricular fistula, canal atresia and cleft anomaly imply an increased risk of COM. Other factors such as residency, education, social class, height, history of breast feeding, microtia, nasal septal deviation, nasal polyposis and nasal allergic symptoms showed little influence on COM.

Prevalence of otitis media and allied diseases in Korea--results of a nation-wide survey, 1991

A nation-wide survey was conducted to estimate the prevalence of otitis media and allied diseases through physical examination by otolaryngologic doctors from July to October, 1991. A sample study population was selected from a panel to be representative of the Korean population by multistage clustered and stratified random sampling method based on the National Census Data, 1990. Total number of subjects undertaken were 9,321, Which were drawn from 2,899 households residing in 60 different areas throughout the country. The overall prevalence of otitis media was 2.85% (3.10% of males and 2.61% of females). Prevalence of each subtype was as follows; acute otitis media, 0.02%; middle ear effusion, 0.60%; chronic otitis media, 2.19%, respectively. The prevalence of otitis media did not vary by sex, nor by urban-rural difference. There was an increasing tendency of the prevalence of otitis media by age. However, the prevalence of both middle ear effusion and acute otitis media showed a decreasing pattern by age. Particularly noteworthy was a significant geographic variation in the prevalence of otitis media by provinces. The prevalence rate of septal deviation was 21.93% and the presence of septal deviation was significantly related to that of otitis media (p < 0.05). The prevalence rates of nasal allergic symptoms, nasal polyposis and evident cleft palate were 1.14%, 1.00% and 0.07%, respectively. The presence of otitis media was significantly correlated with both nasal allergic symptoms (P < 0.1) and evident cleft palate (P < 0.05), but not with that of nasal polyposis.

Intraventricular neurocytoma: clinicopathological analysis of seven cases

A retrospective analysis of seven patients with intraventricular neurocytoma is presented. Patient age at diagnosis ranged from 15 to 38 years (mean 24.6 years) and the male:female ratio was 6:1. Raised intracranial pressure due to hydrocephalus was the main cause of the clinical manifestations. An isodense mass with multiple intratumoral cysts and homogeneous contrast enhancement was the characteristic computerized tomography finding. The lesions commonly involved the lateral ventricle with or without extension to the third ventricle. Cerebral angiography showed homogeneous vascular staining in five patients. Magnetic resonance images revealed a mass isointense with the cerebral cortex on both T1- and T2-weighted images. Gadolinium-diethylenetriaminepenta-acetic acid-enhanced images showed homogeneous enhancement. Total removal of the tumor was possible in four patients. Pathologically, six cases were initially diagnosed as oligodendroglioma and the remaining case as ependymoma. However, immunohistochemical studies demonstrated strong positivity for neuron-specific enolase in all seven cases and for synaptophysin in five cases. On electron microscopy, three cases showed well-defined neurosecretory granules and 10-nm microtubules in their cytoplasm and cytoplasmic processes. One patient developed a recurrent tumor 18 months after surgery. The remaining six patients are free of recurrent tumors at 2 to 62 months after surgery. It is suggested that neurocytoma must be included in the differential diagnosis of intraventricular lesions, and that electron microscopic and immunohistochemical studies should be undertaken.

Malignant triton tumor of the acoustic nerve. Case report

The authors present the clinical, radiological, pathological features, and autopsy findings of a patient with malignant triton tumor of the acoustic nerve, which probably arose from a pre-existing acoustic schwannoma. The term "malignant triton tumor" is applied to malignant schwannomas with rhabdomyoblastic differentiation. A cerebellopontine angle tumor with spinal drop metastasis occurred in this patient 10 months after near-total removal of the original tumor.

A three-dimensional micro-organ culture system optimized for in vitro growth of human malignant brain tumors

A brain tumor is composed not only of tumor cells, but also of normal glial, mesenchymal, endothelial, and microglial cells, as well as lymphocytes and macrophages. Therefore, homogeneous cultures of tumor cells, currently used for chemosensitivity testing, do not accurately model in situ tumors. We have developed an in vitro growth assay for brain tumors that includes normal host cells and is potentially useful for studies of chemotherapy and biological response modifiers. Human glioblastoma xenografts (U251-MG) were resected from mice, minced, and explanted into agarose-coated culture wells. After 5 to 7 days, microtumors emerged as expanding spheroids, which grew most efficiently in minimum essential medium supplemented with 20% fetal calf serum, 90% of which was replaced on alternate days. The growth rate and bromodeoxyuridine labeling index were similar in the microtumors and the xenografts, and light microscopy revealed highly cellular, pleomorphic tumors with high mitotic activity in both. Immunohistochemical studies also demonstrated the persistence of macrophages in both xenografts and microtumors. Microtumors treated for 2 hours with 75 mumol/L 1,3-bis-(2-chloroethyl)-1-nitrosourea showed a growth delay of 1.5 days; no effects were observed after treatment with lower doses. This in vitro system for brain tumor culture may provide a useful technique for the study of new therapies as an alternative to in vivo xenograft studies using immunodeficient animals.

Separation of amino- and acetylamino-polycyclic aromatic hydrocarbons by reversed- and normal-phase high-performance liquid chromatography

In the field of chemical carcinogenesis, amino- and acetylamino-polycyclic aromatic hydrocarbons (PAHs) are among the most studied compounds. Many of these compounds have recently been detected in the environment. Presently, knowledge permitting predictions of the high-performance liquid chromatographic (HPLC) retention order of amino- and acetylamino-PAHs, particularly among their geometric isomers is lacking. In order to obtain a better understanding of the separation of these types of compounds, we have studied the separation of a series of structurally related amino- and acetylamino-PAHs derived from naphthalene, phenanthrene, anthracene, pyrene, benz[a]anthracene, benzo[a]pyrene, and benzo[e]pyrene by using reversed-phase and normal-phase HPLC columns of different types (monomeric, polymeric, and chiral stationary phase). The results indicate: (i) Pirkle-type chiral stationary phase columns and the Zorbax SIL column can efficiently separate both the amino-PAHs and acetylamino-PAHs; (ii) in general, there was no correlation between retention time and molecular size; (iii) when acetylamino-PAHs were separated on the monomeric Zorbax ODS column, the isomer with the acetylamino group located at the carbon position of higher electron density has a shorter retention time; and (iv) separation of the parent PAHs was better than that of the amino-PAHs and acetylamino-PAHs. Our results thus may provide useful information for the analysis of amino-PAHs, particularly for distinguishing the geometric isomers of environmental samples.

Acute cerebral infarction and changes of regional cerebral blow flow (rCBF) following experimental middle cerebral artery (MCA) occlusion

An unanaesthetized cat model of acute focal cerebral ischaemia has been established by the technique of transorbital snare ligature for middle cerebral artery (MCA) occlusion. The model was used to investigate the patterns of changes of regional cerebral blood flow (rCBF) for up to 16 h following MCA occlusion by the hydrogen clearance technique and to explore the correlation among changes of rCBF, neurological deficits, and pathological changes. The animals were divided into 2 groups according to the size of infarct which was identified by 2% triphenyl tetrazolium chloride (TTC) solution stain. Infarct larger than 10% of coronal section surface of ipsilateral hemisphere was found in 18 cats (Group A), and a smaller infarct was found in the remaining 7 cats (Group B). Between these 2 groups, there was a statistically significant difference in the average rCBF value of the ipsilateral MCA territory. The increasing grade of contralateral paralysis correlated well with the decreasing rCBF in the ipsilateral MCA territory, and the increasing grade of cerebral hemispheric swelling was directly proportional to the increasing grade of paralysis. Three patterns of changes of rCBF were observed: persistent severe ischaemia (15 cats, Group A); persistent mild to moderate ischaemia (7 cats, Group B); and immediate severe ischaemia followed by early post-ischaemic hyperaemia and death (3 cats, Group A). During the initial stage of ischaemia, a significant decrease in rCBF of the contralateral hemisphere was observed in both groups, however, in Group A rCBF gradually increased to preocclusion level, while Group B presented a further decrease in rCBF suggesting the occurrence of interhemispheric diaschisis. Thus, Group B appeared to take advantage of diaschisis during the late phase of infarct development, as well as the substantial collateral flow from the surrounding anterior and posterior cerebral artery territories.