Delayed lupus nephritis in the course of systemic lupus erythematosus is associated with a poorer treatment response: a multicentre, retrospective cohort study in Japan.

OBJECTIVE: The objective of this study was to investigate possible differences in treatment responses between two categories for the onset of lupus nephritis. METHODS: We performed a multicentre, retrospective cohort study of class III-V lupus nephritis patients diagnosed between 1997 and 2014. The renal responses to initial induction therapy were compared between patients who developed lupus nephritis within one year from diagnosis of systemic lupus erythematosus (early (E-) LN) and the remainder (delayed (D-) LN) using the Kaplan-Meier method. We determined the predictors of renal response as well as renal flares and long-term renal outcomes using multivariate Cox regression analyses. RESULTS: A total of 107 E-LN and 70 D-LN patients were followed up for a median of 10.2 years. Log-rank tests showed a lower cumulative incidence of complete response in D-LN compared with E-LN patients. Multivariate analysis identified D-LN (hazard ratio (HR) 0.48, 95% confidence interval (CI) 0.33-0.70), nephrotic syndrome at baseline, and a chronicity index greater than 2 as negative predictors of complete response. D-LN patients were more likely to experience renal flares. D-LN (HR 2.54, 95% CI 1.10-5.83) and decreased renal function were significant predictors of chronic kidney disease at baseline. CONCLUSION: D-LN was a predictor of poorer treatment outcomes, in addition to renal histology and severity of nephritis at lupus nephritis onset.

In vitro splicing analysis showed that availability of a cryptic splice site is not a determinant for alternative splicing patterns caused by +1G-->A mutations in introns of the dystrophin gene.

BACKGROUND: Splicing patterns are critical for assessing clinical phenotype of mutations in the dystrophin gene. However, it is still unclear how to predict alternative splicing pathways in such cases of splice-site mutation in the dystrophin gene. OBJECTIVE: To identify elements determining alternative splicing pathways in intron +1G-->A mutations of the dystrophin gene. RESULTS: We found that exon 25 is spliced out in the +1G-->A mutation in intron 25, resulting in mild Becker muscular dystrophy, and that a cryptic splice site within exon 45 was activated in severe Duchenne muscular dystrophy with a mutation of +1G-->A mutation in 45. Furthermore, in vitro splicing analysis using a pre-constructed expression vector showed that the mutant intron 25 produced one transcript that lacked exon 25. In contrast, the same splice-site mutation in intron 45 produced three splicing products. One product used the same cryptic donor splice site within exon 45 as the in vivo donor site and another product used a cryptic splice site within the vector sequence. Notably, the available cryptic splice site was not activated by the same G-->A mutation of intron 25. CONCLUSION: It was concluded that sequences inserted into the in vitro splicing assay minigene contain cis-elements that determine splicing pathways. By taking other +1G-->A mutations in the introns of the dystrophin gene reported in the literature into consideration, it seems that cryptic splice-site activation is seen only in strong exons. This finding will help to elucidate the molecular pathogenesis of dystrophinopathy and to predict efficiency of induction of exon skipping with antisense oligonucleotides for treatment of Duchenne muscular dystrophy.

[Lobectomy for local recurrence following stereotactic radiotherapy to non-small cell lung cancer].

A 78-year-old man had non-small cell lung cancer (NSCLC) in the left upper lobe (squamous cell carcinoma, cT1N0M0). He preferred less invasive treatment and undertook stereotactic radiotherapy (SRT)[48 Gy/4 Fr] because his forced expiratory volume in 1 second percent (FEV1.0%) was 53.50%. The therapeutic effect was partial response and the adverse reaction was dermatitis (grade 1). Seven months after SRT, local recurrence was detected. The tumor was growing from 3 x 5 mm to 25 x 25 mm in size. Nine months after SRT, left upper lobectomy was performed successfully unaffected by SRT. He is doing well 14 months after the operation without any signs of recurrence. This case might help develop a new strategy for the treatment of stage I NSCLC. It is that patients with stage I NSCLC have SRT as 1st line treatment, and if local recurrence is observed after SRT, lobectomy may be performed.

Dystrophin nonsense mutations can generate alternative rescue transcripts in lymphocytes.

Secondary alterations in splicing have been reported to produce semi-functional mRNA from several nonsense mutations in the dystrophin gene. Disruptions of exonic splicing enhancers by single nucleotide changes are thought to underlie such alterations. The precise frequencies of such nonsense mutation-dependent splicing alterations, however, remain unknown. Here we analyzed the splicing patterns of dystrophin mRNA in lymphocytes from 38 patients with dystrophinopathies due to nonsense mutations in the dystrophin gene. In seven of the cases (18%), we observed partial skipping of the nonsense-encoding exon. Two of the seven cases, however, exhibited complex activation of a nonsense mutation-created splice site, which resulted in the generation of novel transcripts. Examination of cis-regulatory splicing elements through calculation of splicing probability scores and identification of potential splicing enhancer or silencer sequences failed to disclose a single cause for exon skipping. Remarkably, individual differences in splicing patterns were observed for cells from patients with identical nonsense mutations (C.5899C>T). Although five cases produced semi-functional dystrophin mRNAs, only one of these exhibited a mild clinical course. These results provide important insights about targets for exon skipping induced by candidate antisense oligonucleotides and for ribosomal read-through of nonsense mutations.

Modulation of in vitro splicing of the upstream intron by modifying an intra-exon sequence which is deleted from the dystrophin gene in dystrophin Kobe.

Molecular analysis of dystrophin Kobe showed that exon 19 of the dystrophin gene bearing 52-bp deletion was skipped during splicing, although the known consensus sequences at the 5' and 3' splice sites of exon 19 were maintained (Matsuo, M., T. Masumura, H. Nishio, T. Nakajima, Y. Kitoh, T. Takumi, J. Koga, and H. Nakamura. 1991. J. Clin. Invest. 87:2127-2131). These data suggest that the deleted sequence of exon 19 may function as a cis-acting element for exact splicing for the upstream and downstream introns. To investigate this potential role of exon 19, an in vitro splicing system using artificial dystrophin mRNA precursors (pre-mRNAs) was established. Pre-mRNA containing exon 18, truncated intron 18, and exon 19 was spliced precisely in vitro, whereas splicing of intron 18 was almost completely abolished when the wild-type exon 19 was replaced by the dystrophin Kobe exon 19. Splicing of intron 18 was not fully reactivated when dystrophin Kobe exon 19 was restored to nearly normal length by inserting other sequences into the deleted site. These results suggest that the presence of the exon 19 sequence which is lost in dystrophin Kobe is more critical for splicing of intron 18 than the length of the exon 19 sequence. Characteristically, the efficiency of splicing of this intron seemed to correlate with the presence of polypurine tracks within the downstream exon 19. Moreover, an antisense 31-mer 2'-O-methyl ribonucleotide complementary to the 5' half of the deleted sequence in dystrophin Kobe exon 19 inhibited splicing of wild-type pre-mRNA in a dose- and time-dependent manner. This first in vitro evidence that dystrophin pre-mRNA splicing can be modulated by an antisense oligonucleotide raises the possibility of a new therapeutic approach for Duchenne muscular dystrophy.

Disruption of the splicing enhancer sequence within exon 27 of the dystrophin gene by a nonsense mutation induces partial skipping of the exon and is responsible for Becker muscular dystrophy.

The mechanism of exon skipping induced by nonsense mutations has not been well elucidated. We now report results of in vitro splicing studies which disclosed that a particular example of exon skipping is due to disruption of a splicing enhancer sequence located within the exon. A nonsense mutation (E1211X) due to a G to T transversion at the 28th nucleotide of exon 27 (G3839T) was identified in the dystrophin gene of a Japanese Becker muscular dystrophy case. Partial skipping of the exon resulted in the production of truncated dystrophin mRNA, although the consensus sequences for splicing at both ends of exon 27 were unaltered. To determine how E1211X induced exon 27 skipping, the splicing enhancer activity of purine-rich region within exon 27 was examined in an in vitro splicing system using chimeric doublesex gene pre-mRNA. The mutant sequence containing G3839T abolished splicing enhancer activity of the wild-type purine-rich sequence for the upstream intron in this chimeric pre-mRNA. An artificial polypurine oligonucleotide mimicking the purine-rich sequence of exon 27 also showed enhancer activity that was suppressed by the introduction of a T nucleotide. Furthermore, the splicing enhancer activity was more markedly inhibited when a nonsense codon was created by the inserted T residue. This is the first evidence that partial skipping of an exon harboring a nonsense mutation is due to disruption of a splicing enhancer sequence.

Identification of a novel first exon in the human dystrophin gene and of a new promoter located more than 500 kb upstream of the nearest known promoter.

The dystrophin gene, which is mutated in patients with Duchenne and Becker muscular dystrophies, is the largest known human gene. Five alternative promoters have been characterized until now. Here we show that a novel dystrophin isoform with a different first exon can be produced through transcription initiation at a previously unidentified alternative promoter. The case study presented is that of a patient with Duchenne muscular dystrophy who had a deletion extending from the 5' end of the dystrophin gene to exon 2, including all promoters previously mapped in the 5' part of the gene. Transcripts from lymphoblastoid cells were found to contain sequences corresponding to exon 3, indicating the presence of new promoter upstream of this exon. The nucleotide sequence of amplified cDNA corresponding to the 5' end of the new transcript indicated that the 5' end of exon 3 was extended by 9 codons, only the last (most 3') of which codes for methionine. The genomic nucleotide sequence upstream from the new exon, as determined using inverse polymerase chain reaction, revealed the presence of sequences similar to a TATA box, an octamer motif and an MEF-2 element. The identified promoter/exon did not map to intron 2, as might have been expected, but to a position more than 500 kb upstream of the most 5' of the previously identified promoters, thereby adding 500 kb to the dystrophin gene. The sequence of part of the new promoter region is very similar to that of certain medium reiteration frequency repetitive sequences. These findings may help us understand the molecular evolution of the dystrophin gene.

Prophylactic fresh frozen plasma may prevent development of hepatic VOD after stem cell transplantation via ADAMTS13-mediated restoration of von Willebrand factor plasma levels.

We initially conducted a multicenter, randomized trial (n=43), and subsequently a questionnaire study (n=209) of participating hospitals, to evaluate whether infused fresh frozen plasma (FFP) could prevent the occurrence of hepatic veno-occlusive disease (VOD) after stem cell transplantation (SCT). Forty-three patients were divided into two groups: 23 receiving FFP infusions and 20 not receiving it. VOD developed in three patients not receiving FFP. Plasma von Willebrand factor (VWF) antigen levels were lower at days 0, 7 and 28 after SCT in patients receiving FFP than in those not receiving it, whereas plasma ADAMTS13 activity (ADAMTS13:AC) did not differ between them. Plasma VWF multimer (VWFM) was demonstrated to be defective in the high approximately intermediate VWFM during the early post-SCT phase, but there was a significant increase in high VWFM just before VOD onset. This suggests that a relative enzyme-to-substrate (ADAMTS13/high-VWFM) imbalance is involved in the pathogenesis of VOD. To strengthen this hypothesis, the incidence of VOD was apparently lower in patients receiving FFP infusions than in those not receiving it (0/23 vs 3/20) in the randomized trial. Further, the results combined with the subsequent questionnaire study (0/36 vs 11/173) clearly showed the incidence to be statistically significant (0/59 vs 14/193, P=0.033).

p53 protein accumulates frequently in early bronchial neoplasia.

p53 mutations are common in human lung cancer and frequently generate levels of p53 protein that are detectable by immunohistochemistry. For this reason, p53 protein accumulation is a candidate biomarker, but little is known about its timing or frequency in multistage bronchial carcinogenesis. We studied human lung tissues containing preinvasive squamous neoplasms from 34 donors with and without lung cancer. Nuclear p53 protein was present in 0% of normal mucosas, 6.7% of squamous metaplasias, 29.5% of mild dysplasias, 26.9% of moderate dysplasias, 59.7% of severe dysplasias, 58.5% of carcinomas in situ, 67.5% of microinvasive carcinomas, and 79.5% of invasive tumors. These data indicate that (a) p53 protein accumulates in about 30% of the earliest recognized neoplastic lesions (i.e., mild dysplasia), (b) there is an increasing frequency of p53 protein accumulation starting with mild dysplasia, and (c) p53 protein accumulates infrequently in normal or metaplastic mucosa. In a subset of six patients whose most advanced lesion was carcinoma in situ without evidence of invasive cancer, p53 protein was detected in 0% of normal mucosas, 8.3% of squamous metaplasias, 37.5% of mild dysplasias, 12.5% of moderate dysplasias, 93.8% of severe dysplasias, and 55% of carcinoma in situ lesions. These data show clearly that p53 alterations can occur before invasion and suggest that the frequency is similar to that observed in the full series. Since two-thirds or more of lung cancers have p53 alterations, the timing and frequency of p53 protein accumulation make the p53 tumor suppressor gene an attractive marker for early diagnosis and evaluation of chemoprevention agents.

[Intralobar pulmonary sequestration with high level of serum CEA; report of a case].

We reported a case of intralobar pulmonary sequestration with a high level of the serum CEA. A 53-year-old woman whose chief complaint was cough was admitted to our hospital. Enhanced chest computed tomography (CT) revealed the mass in the left lower lung, lymph-nodes swelling, and the aberrant artery. Magnetic resonance angiography (MRA) conformed the aberrant artery from the descending aorta. The level of serum CEA elevated at 9.6 ng/ml. Left lower lobectomy was performed. A diagnosis of intralobar pulmonary sequestration (Pryce type II) was established in this case. Histopathologically, the peribronchial epithelial cells in pulmonary sequestration showed weak positive for anti-CEA monoclonal antibody. Postoperative course was uneventful and the serum CEA level was 3.5 ng/ml in the normal range at the postoperative 17th day.

Gene amplification and protein expression of EGFR and HER2 by chromogenic in situ hybridisation and immunohistochemistry in atypical adenomatous hyperplasia and adenocarcinoma of the lung.

AIMS: To investigate the importance of gene amplification and EGFR (epidermal growth factor receptor) and HER2 protein expression during the progression of adenocarcinoma of the lung. METHODS: EGFR and HER2 gene amplification was examined in atypical adenomatous hyperplasia (AAH), bronchioloalveolar carcinoma (BAC), and adenocarcinoma with mixed subtypes (MX) by chromogenic in situ hybridisation (CISH), and protein expression was examined by immunohistochemistry using paraffin wax embedded tissues. RESULTS: EGFR and HER2 gene amplification was found in four and two of 86 cases, respectively, and was detected only in the invasive components of MX. EGFR and HER2 protein expression was seen in 24 and 18 of 86 cases, respectively. EGFR and HER2 proteins were not expressed in AAH but were expressed in one BAC case each. EGFR and HER2 proteins were expressed in 23 and 17 of 55 adenocarcinomas with MX. EGFR and HER2 protein expression was seen more often in the invasive components than in the BAC components of MX, and increased significantly as lesions progressed from AAH to BAC, early MX, and overt MX. Because EGFR and HER2 protein expression was frequently seen without gene amplification, other mechanisms apart from gene amplification may be associated with protein expression. CONCLUSIONS: EGFR and HER2 gene amplification may be a late event and EGFR and HER2 protein expression may be associated with the development of adenocarcinoma of the lung.

Rescue of dystrophin mRNA of Duchenne muscular dystrophy by inducing exon skipping.

Duchenne muscular dystrophy (DMD) is a fatal muscle-wasting disease, and its victims usually succumb in their twenties. Many studies, including investigations into gene-replacement therapy, have been conducted in a search for a treatment for DMD, and the most promising treatment to date is rescue of mutant dystrophin mRNA by induction of exon skipping. On the basis of results from the molecular analysis of dystrophin Kobe, we propose a treatment for DMD in which antisense oligonucleotides induce exon skipping to edit out-of-frame dystrophin mRNA into in-frame, thereby converting severe DMD to a milder form. Here we review the progress of development of this alternative treatment, with a special focus on dystrophin Kobe.

[Mucoepidermoid carcinoma with high level of serous carcinoembryonic antigen; report of a case].

We reported a case of mucoepidermoid carcinoma with a high level of the serum CEA. A 38-year-old woman was admitted because of abnormal chest shadow. Bronchoscopy revealed polypoid tumor occluding the lumen of right B3 bronchus. Bronchoscopic biopsy suggested a diagnosis of tubular adenocarcinoma. Chest computed tomography (CT) confirmed the mass in the right upper lung field and the swelling of right bronchial lymph node. The CEA level of serum elevated at 12.4 ng/ml. A right upper and middle lobectomy with mediastinal lymph nodes dissection was performed on August 26, 2003. Histopathologically, the polypoid tumor was a low grade mucoepidermoid carcinoma with partially extrabronchial extension. However, no lymph nodes metastasis were noted. The cytoplasms of about 45% of tumor cells showed positive for anti-CEA monoclonal antibody. Pathological stage was IB (T2N0M0). Seventeen months has passed with no evidence of recurrence and the CEA level of serum was in the normal range.

[Pulmonary pleomorphic carcinoma].

Pleomorphic carcinoma is a rare primary pulmonary malignancy. We report 2 surgical cases of pulmonary pleomorphic carcinoma. The first case was a 71-year-old male. Chest computed tomography (CT) showed a rapidly growing tumor with irregular density. Transbronchial lung biopsy revealed the tumor to be malignant. Left lower lobectomy was performed. Pathological diagnosis was pleomorphic carcinoma (pT2N2M0, stage IIIA). He died 8 months after surgery due to brain metastasis and mediastinal lymph node metastasis. The second case was a 74-year-old male who complained of bloody sputum. Chest CT showed a tumor with cavity in the right middle lobe. Brushing cytology under bronchofiberscopy revealed atypical cell. Right middle lobectomy and partial resection of the right lower lobe were performed. Pathological diagnosis was also pleomorphic carcinoma (pT2N0M0, stage IB). He has no findings of recurrence nor metastasis 15 months after the operation.

A novel expression vector for the cyanobacterium, Synechococcus PCC 6301.

A cyanobacterial expression vector was constructed using ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) promoter and terminator sequences derived from Synechococcus PCC 6301. recombinant plasmid, designated pARUB19, has an ampicillin-resistant (ApR) gene as a selectable marker and four unique restriction sites to allow the insertion of foreign genes. Using this vector, the luciferase gene from the firefly, Photinus pyralis, was introduced into Synechococcus PCC 6301 cells. The luciferase expression vector could be maintained stably in the host cells. Light production of luciferin/luciferase was detected in the transformants. Luciferase amounted to 1.2% of the total soluble protein. This plasmid may facilitate higher levels of foreign gene expression in Synechococcus PCC 6301.

A novel deletion of the dystrophin S-promoter region cosegregating with mental retardation.

A contiguous deletion of the S-promoter/first S exon and its downstream exon 56 of the dystrophin gene was identified in a Japanese dystrophinopathy family in which two brothers and their half brother were affected. Characteristically, severe mental retardation cosegregated with the deletion even though they grew up in different environments. Furthermore, mild cerebral atrophy was observed by CT scan and MRI in the eldest brother.

Amino-terminal deletion of 53% of dystrophin results in an intermediate Duchenne-Becker muscular dystrophy phenotype.

We report a Japanese boy with muscular dystrophy whose clinical symptoms were intermediate between those usually considered typical of Duchenne and Becker muscular dystrophies. The patient had a large inframe deletion extending from exons 3 to 41 of the dystrophin gene, which would be expected to cause the production of a dystrophin protein composing only 53% of the normal polypeptide chain. Such an inframe deletion would be expected to cause Becker muscular dystrophy. We did not obtain evidence for alternative splicing or for RNA editing. Immunocytochemical analysis of skeletal muscle showed that a dystrophin-related polypeptide was detectable with antibody directed against the carboxyl-terminal part of the polypeptide but not with antibodies directed against the amino-terminal part, although labeling by antibody against the carboxyl-terminal was faint and patchy. The severity of the disease in this case may be due to the lack of the amino-terminal, actin-binding domain of dystrophin.

Decreased expression of full-length mRNA for cBCD541 does not correlate with spinal muscular atrophy phenotype severity.

Spinal muscular atrophy (SMA) is characterized by degeneration of spinal cord anterior horn cells and muscular atrophy and has three phenotypes based on clinical severity and age of onset. One of the responsible genes for SMA is the survival motor neuron (SMN) gene, which is homozygously absent or interrupted in more than 90% of SMA patients. The cBCD541 (BCD) gene is a highly homologous copy of the SMN gene, which has a single synonymous transition in the coding region and may compensate for the loss of the SMN gene. To evaluate the effects of the BCD gene expression on the phenotypes of SMA, we examined lymphocyte mRNA from 9 SMA patients lacking the SMN gene, 10 asymptomatic parents, and 15 control subjects. We amplified mRNA fragments containing exon 7 of the SMN or BCD genes using reverse transcription-polymerase chain reaction since the transcript lacking exon 7 encodes a putative protein with a different C-terminal end. We used glyceraldehyde-3-phosphate dehydrogenase (GAPDH) transcript as an internal control, and the relative expression level of the SMN or BCD gene was shown as the ratio of SMN or BCD transcript to GAPDH transcript (S/G ratio). The mean S/G ratios of the patients were significantly lower than that of the parents and controls. However, among the patients examined in this study, there was no relationship between the S/G ratios and phenotypes of SMA. The results showed that the BCD gene expression was not related to the phenotypes of SMA. Furthermore, there was an overlap between the S/G ratios in patients and controls. As our discrimination study showed that the S/G ratio reflected the expression of the BCD transcripts in patients and the SMN transcripts in controls, this finding suggested that the BCD gene expression per se does not compensate for the loss of the SMN gene.

The auditory evoked magnetic fields to very high frequency tones.

We studied the auditory evoked magnetic fields (AEFs) in response to pure tones especially at very high frequencies (from 4000 Hz to 40,000 Hz). This is the first systematic study of AEFs using tones above 5000 Hz, the upper audible range of humans, and ultrasound. We performed two experiments. In the first, AEFs were recorded in 12 subjects from both hemispheres under binaural listening conditions. Six types of auditory stimulus (pure tones of five different frequencies: 4000 Hz, 8000 Hz, 10,000 Hz, 12,000 Hz, 14,000 Hz, and a click sound as the target stimulus) were used. In the second experiment, we used 1000 Hz, 15,000 Hz, and two ultrasounds with frequencies of 20,000 Hz and 40,000 Hz. The subjects could detect all stimuli in the first experiment but not the ultrasounds in the second experiment. We analyzed N1m, the main response with approximately 100 ms in peak latency, and made the following findings. (1) N1m responses to the tones up to 12,000 Hz were clearly recorded from at least one hemisphere in all 12 subjects. N1m for 14,000 Hz was identified in at least one hemisphere in 10 subjects, and in both hemispheres in six subjects. No significant response could be identified to ultrasounds over 20,000 Hz. (2) The amplitude of the N1m to the tones above 8000 Hz was significantly smaller than that to 4000 Hz in both hemispheres. There was a tendency for the peak latency of the N1m to be longer for the tones with higher frequencies, but no significant change was found. (3) The equivalent current dipole (ECD) of the N1m was located in the auditory cortex. There was a tendency for the ECD for the tones with higher frequencies to lie in more medial and posterior areas, but no significant change was found. (4) As for the interhemispheric difference, the N1m amplitude for all frequency tones was significantly larger and the ECDs were estimated to be located more anterior and medial in the right hemisphere than the left. The priority of the right hemisphere, that is the larger amplitude, for very high frequency tones was confirmed. (5) The orientation of the ECD in the left hemisphere became significantly more vertical the higher the tones. This result was consistent with previous studies which revealed the sensitivity of the frequency difference in the left hemisphere. From these findings we suggest that tonotopy in the auditory cortex exists up to the upper limit of audible range within the small area, where the directly air-conducted ultrasounds are not reflected.

Immunohistochemical study of Ki-67 (MIB-1), p53 protein, p21WAF1, and p27KIP1 expression in benign, atypical, and anaplastic meningiomas.

Histologic grading of meningiomas has prognostic and clinical therapeutic implications. Meningiomas were histologically classified into 3 different World Health Organization grades. Grade II, an atypical meningioma, was defined by major and various minor histologic criteria. However, these histologic criteria sometimes are not fulfilled, and other criteria are necessary. We studied and analyzed the immunohistochemical expression of MIB-1, p53, p21WAF1, p27KIP1 proteins in 146 cases of meningiomas, including 109 benign, 27 atypical, and 10 anaplastic meningiomas. Most of the benign meningiomas expressed low MIB-1 labeling index (mean, 1.5%), and fewer cases had p53 protein expression. In contrast, the anaplastic meningiomas had a high labeling index of MIB-1 (mean, 19.5%) and always expressed p53 protein, with a mean labeling index of 6.3%. The atypical meningiomas had MIB-1 and p53 labeling indexes in the range between benign and anaplastic meningiomas, with mean labeling indexes of 8.1% and 3.5%, respectively. These expressions were statistically significant among benign, atypical, and anaplastic meningiomas (P <.001). We conclude that the immunohistochemistry of MIB-1 and p53 protein will be valuable in discriminating atypical meningiomas from benign or anaplastic meningiomas, at least in histologically borderline cases. In addition, we also found direct correlation of p21 and inverse correlation of p27 expressions in meningiomas with increasing histologic grade and proliferative index.