[Investigation of small airway function of occupational asthma at different stages]

Objective: To analyze the characteristics of small airway dysfunction in patients with occupational asthma, and explore the significance of small airway function indicators in the evaluation of occupational asthma. Methods: A total of 53 patients with occupational asthma diagnosed in our hospital from December 2008 to December 2018 were retrospectively collected in May 2020. 55 healthy people were included as the control group (NC group) and 58 bronchial asthma patients as BA group. The general information and baseline pulmonary function (FVC、FEV(1)、PEF) of the subjects were collected, the pulmonary function were reexamined and small airway function (FEF(25%)pred、FEF(50%)pred、FEF(75%)pred、MMEF(25-75%)pred) were tested at the time of diagnosis and remission. Results: There was no significant difference in pulmonary function and asthma control score (ACT) between OA group and BA group (P=0.356, 0.610, 0.364, 0.430, 0.533, 0.759, 0.426, 0.632) . The incidence of small airway dysfunction in OA group was 77.4%. The indexes of small airway function (FEF(25%)pred, FEF(50%)pred, FEF(75%)pred, MMEF(25-75%)pred) were lower than those in the NC group (P<0.001) . The small airway function indexes of mild and moderate OA patients in remission stage were improved (P=0.029, 0.182) , but the abnormal rate of small airway function was still 62.3%, and there was no significant difference compared with those at the time of diagnosis (P=0.091) . Small airway function (MMEF(25-75%)pred, FEF(50%)pred) was correlated with large airway function (FEV(1)% pred, PEF% pred) (P=0.001) . Conclusion: Small airway dysfunction often occurs and persists in patients with occupational asthma, and has a certain correlation with large airway function indexes.

Cross-cultural Adaptation and Multi-centric Validation of the Motor Function Measure Chinese Version (MFM-32-CN) for Patients with Neuromuscular Diseases

Aim: This study aims to produce a Chinese translation and adaptation of the MFM-32 and examine its measurement parametric properties in Chinese population with neuromuscular diseases. Methods: The MFM-32-CN was validated by testing reliability, internal consistency, and construct validity. Results: The Interrater and intrarater reliability of MFM-32-CN were moderate to excellent for each item, and excellent for the total score and the subscores. The internal consistency was high for the global scale and subscales. The total score was strongly related to the VAS and Vignos grade, and to a lesser degree to the Brooke grade. The discriminant validity was good. Conclusion: MFM-32-CN has satisfactory reliability, internal consistency, convergent validity and discriminant validity in youngsters with DMD, and good psychometric properties have also been observed for the whole population tested combining different NMD groups, but future study with a larger number of participants in each disease group is needed to confirm the present results.

Evaluation of photolysis and hydrolysis of pyraclostrobin in aqueous solutions and its degradation products in paddy water

This study evaluated the hydrolysis and photolysis kinetics of pyraclostrobin in an aqueous solution using ultra-high-performance liquid chromatography-photodiode array detection and identified the resulting metabolites of pyraclostrobin by hydrolysis and photolysis in paddy water using high-resolution mass spectrometry coupled with liquid chromatography. The effect of solution pH, metal ions and surfactants on the hydrolysis of pyraclostrobin was explored. The hydrolysis half-lives of pyraclostrobin were 23.1-115.5 days and were stable in buffer solution at pH 5.0. The degradation rate of pyraclostrobin in an aqueous solution under sunlight was slower than that under UV photolysis reaction. The half-lives of pyraclostrobin in a buffer solution at pH 5.0, 7.0, 9.0 and in paddy water were less than 12 h under the two light irradiation types. The metabolites of the two processes were identified and compared to further understand the mechanisms underlying hydrolysis and photolysis of pyraclostrobin in natural water. The extracted ions obtained from paddy water were automatically annotated by Compound Discoverer software with manual confirmation of their fragments. Two metabolites were detected and identified in the pyraclostrobin hydrolysis, whereas three metabolites were detected and identified in the photolysis in paddy water.

Enhanced SOCS3 in osteoarthiritis may limit both proliferation and inflammation

Osteoarthritis (OA) is a degenerative joint disease that is characterized by localized inflammatory and secondary proliferative changes. Suppressor of cytokine signaling 3 (SOCS3) is elevated during OA development. We investigated the effects of this protein on human chondrocyte survival in OA and the inflammatory response together with the mechanisms of these effects. Small interfering RNA (siRNA) was used to knock down the expression of SOCS3 in interleukin(IL)-1β-induced primary human osteoarthritic chondrocytes. We found that siRNA-mediated SOCS3 knock-down in human osteoarthritic chondrocytes increased production of IL-1β-induced prostaglandin E₂, cell growth, transcript level and nuclear translocation of cyclin D1. Silencing of SOCS3 resulted in altered expression of nuclear factor-kappa-B (NF-κB) and cyclooxygenase (COX2). Our findings indicate that enhanced SOCS3 could have contradictory influences on OA development. SOCS3 might protect damaged joints by its anti-inflammatory effect and by inhibition of over-augmented cartilage tissue repair, which could exhibit inhibitory properties for joint inflammation, abnormal chondrocyte clustering and osteophyte formation in OA. On the other hand, SOCS3 might reduce chondrocyte growth response, which would delay repair of subchondral cancellous bone damage in OA owing to its anti-proliferation effect. The anti-inflammation and growth inhibition effects exhibited by enhanced SOCS3 in OA appear to be related to its capacity to down-regulate expression levels of NF-κB and COX2.

Chest imaging comparison between non-tuberculous and tuberculosis mycobacteria in sputum acid fast bacilli smear-positive patients

OBJECTIVE

The aim of this study was to distinguish and compare the chest imaging features of non-tuberculous mycobacteria lung disease (NTM-LD) and pulmonary tuberculosis (PTB) in patients with sputum acid fast bacillus (AFB)-smear positive since an earlier differential diagnosis between these two is very important in clinical practice.

PATIENTS AND METHODS

A total of 4167 previously untreated cases with AFB smear-positive sputum were collected from January 2011 to January 2014, in Shanghai Pulmonary Hospital, Tongji University, China. Among them, 124 cases were identified with NTM-LD after specimen culture and strain identification. A cohort of 210 patients with PTB was randomly selected from the remaining 4043 cases with PTB as comparator. The clinical and chest computed tomography (CT) imaging data were compared.

RESULTS

The most prevalent pathogens in patients with NTM-LD were Mycobacterium abscessus (42%, 52/124) and Mycobacterium intracellulare (34%, 42/124). Univariate analysis showed patients with NTM-LD more frequently had bronchiectasis (85.5% vs. 45.7%, p < 0.001), thin-walled cavity (D ≥ 3 cm) (16.9% vs. 7.6%, p = 0.011) compared to PTB patients. Additionally, the location of lesion also differed and the right middle lobe (23.9% vs. 16.3%, p < 0.001) and left lingual segment bronchiectasis (19.9% vs. 8.2%, p < 0.001) were more prominent in NTM-LD. Multivariate analysis showed, bronchiectasis (OR = 8.521, 95% CI: 4.209-17.250, p < 0.001) and thin-walled cavity (D ≥ 3 cm) (OR = 3.561, 95% CI: 1.394-9.097, p = 0.008) were also the independent predictors for the diagnosis of NTM-LD.

CONCLUSIONS

Bronchiectasis in the right middle lobe or left lingual segment and thin-walled cavity with a diameter of more than 3 cm are the frequently the chest CT features in patients with NTM-LD, which might be helpful for an early diagnosis in patients with AFB-smear positive.

Management and outcome of ovarian malignancy complicating pregnancy: an analysis of 41 cases and review of the literature

OBJECTIVE

The aims of this study are to summarize our experience of managing ovarian malignancy complicating pregnancy, to discuss the maternal and fetal outcomes, and to review the literature concerned.

METHODS

Forty-one patients with ovarian malignancies complicating pregnancy at Peking Union Medical College Hospital between 1990 and 2012 were retrospectively reviewed.

RESULTS

Of the 41 patients, malignancies included epithelial ovarian cancers (13/41, 31.7 %), epithelial borderline ovarian tumors (12/41, 29.3 %), ovarian malignant germ cell tumors (10/41, 24.4 %), sexcord stromal tumors (3/41, 7.3 %), metastatic ovarian tumors (2/41, 4.9 %), and primary ovarian choriocarcinoma (1/41, 2.4 %). The median overall survival was 30 months (range 3-165), with an overall mortality rate of 24.4 %. The pregnancy outcomes included termination in the first trimester (8/41, 19.5 %), full-term vaginal delivery (7/41, 17.0 %), full-term cesarean section (17/41, 41.5 %), and therapeutic cesarean section for premature birth (9/41, 22.0 %). One preterm newborn died, and the remaining 32 survived in healthy status. All patients underwent surgery, and those who deliberately delayed radical surgery had gloomy prognosis. Two patients received chemotherapy during pregnancy, and 24 patients started chemotherapy after pregnancy termination.

CONCLUSIONS

Management priority should be given to the malignancy of ovarian tumors at any stage of pregnancy. Surgical intervention is the main treatment modality, and delaying of radical surgery is not recommended for patients with suspicion of high malignancy. Early diagnosis and appropriate treatment could offer satisfactory prognosis.

250 HUMAN EXHALED AIR CAN EFFECTIVELY SUPPORT IN VITRO MATURATION OF PORCINE OOCYTES AND SUBSEQUENT IN VITRO DEVELOPMENT

The objective of the present study was to examine the feasibility of culturing porcine oocytes and embryos in vitro using the human exhaled lung air atmosphere. In Experiment 1, the effects of lung air atmosphere on nuclear maturation of prepubertal gilt oocytes and subsequent development in vitro of parthenogenetic-activated and somatic-cell-cloned embryos were explored. Abattoir-derived prepubertal gilt cumulus–oocyte complexes (COC) were matured in TCM-199 supplemented with 10 IU mL–1 of eCG, 10 IU mL–1 of hCG, 10 ng mL–1 of epidermal growth factor, and 10% porcine follicular fluid (pFF) for 40 to 44 h at 38.5°C, 100% humidity, and 5% CO2+20% O2 (high oxygen tension) or human exhaled air encapsulated in plastic, airtight bags (lung air) or 5% CO2+7% O2 (low oxygen tension) in the incubator. Nuclear maturation was evaluated by the presence of the 1st polar body. For parthenogenetic activation, denuded oocytes with the 1st polar body were selected and stimulated with a single 1.6-kV/cm, 100-μs direct current pulse followed by culture in porcine zygote medium-3. For NT, denuded metaphase II oocytes were enucleated, and then the donor cell was directly injected into the perivitelline space. After NT, reconstructed couplets were fused and activated electrically followed by treatment in 7.5 μg mL–1 of cytochalasin B and 10 μg mL–1 of cycloheximide for 4 to 6 h before culture in porcine zygote medium-3. We found no significant difference among groups in terms of nuclear maturation rate (66.5% v. 60.2%, 63.2%), cleavage rate (94.8% v. 94.2%, 85.2%), blastocyst formation rate (39.5% v. 40.3%, 32.5%), and total cell number (37 v. 38, 32). Moreover, as for porcine cloned embryo, no significant difference between the lung-air and high-oxygen (20% O2) groups was observed in the cleavage rate (88.3% v. 80.3%), blastocyst formation rate (7.3% v. 10.7%), and total cell number (34 v. 36). The above results indicated that porcine oocytes can be matured in vitro safely and efficiently using the human exhaled lung air atmosphere. In Experiment 2, in vitro developmental competence of porcine zona-free parthenogenetically activated embryos cultured in a lung air, low oxygen (5% O2), or high oxygen (20% O2) tension gas environment was studied. We found no obvious difference among the 3 groups regarding the rates of cleavage (83.0%, 83.6%, 82.8%), but blastocyst formation rate (26.8% v. 48.6%, 48.2%) and total cell number (23 v. 34, 29) in lung air were lower than those in the rest of the groups (P < 0.05). The results show that lung air could be an alternative for preparing a gas environment for in vitro culture of porcine zona-free parthenotes, although not an ideal alternative. Taken together, porcine oocytes and embryos can be cultured in vitro safely and efficiently using the human exhaled lung air atmosphere. Z. B. Cao and L. C. Sui contributed equally to this work. X. R. Zhang and Y. H. Zhang are the corresponding authors. This work was supported by NSFC (30700574), 863 (2008AA101003).

139 TRICHOSTATIN A IMPROVED IN VITRO DEVELOPMENT OF PORCINE NUCLEAR TRANSFER EMBRYOS PRODUCED BY A NEW ACTIVATION METHOD

Recently, it has been reported that a new activation method, brief exposure to cycloheximide before electrical activation, could increase development rates and reduce cell death. In our study, we allocated reconstructed SCNT embryos into 3 groups: electrical activation followed by exposure to cycloheximide (10 μg mL–1) for 4 h (ELE+CHX); exposure to cycloheximide (10 μg mL–1) for 10 min followed by electrical activation (CHX+ELE); and electrical pulse treatment alone (ELE). We found the CHX+ELE (10 min) group had a similar blastocyst formation rate and total blastocyst number with the ELE+CHX (4 h) group, and both groups could increase in vitro development compared with the ELE group. Trichostatin A (TSA), an inhibitor of histone deacetylase, has been reported to potentially enhance cloning efficiency. We examine the effect of TSA on nuclear transfer embryos produced by the CHX+ELE activation method. The reconstructed embryos were treated with 50 nM TSA for 0 and 36 h. We found that 50 nM TSA for 36 h after activation had an increased blastocyst rate compared with the control (15.35 v. 8.84%; P < 0.05), but there was no difference in cleavage rate or in total blastocyst numbers. Our data demonstrate that TSA treatment could significantly improve pig nuclear transfer embryos produced by a new activation method. S.L.C., W.W. equal contribution; Corresponding author ZH. X.R., ZH. Y.H.; Supported by NSFC (30700574), 863 (2008AA101003).

316 INDUCTION OF PIG INDUCED PLURIPOTENT STEM CELLS BY RECOMBINANT PROTEINS ENCODED BY DEFINED FACTORS

Pluripotent cells derived from any differentiated cell type through ectopic expression of transcription factors were designated as induced pluripotent stem (iPS) cells, exhibiting similar morphology and growth properties to embryonic stem (ES) cells besides expressing ES cell marker. Because iPS have the ability to differentiate into all types of cells, iPS cell technology is thought to have enormous potential for generating disease models, drug screening, toxicology, and regenerative medicine. However, for virus-mediated transfection of defined factors, the exogenous genes generally would be randomly inserted into the target cell’s genome, possibly bringing the potential hazard of insertional mutagenesis. Therefore, it is necessary to seek some new methods to induce somatic cell reprogramming without viruses. With instruction from the work of Zhou et al. (2009 Cell Stem Cell 4, 381–384), in the present study we attempted to use defined factors recombinant proteins-carried cell-penetrating peptide for the generation of porcine iPS cells, which would be a benefit for safe applications of iPS cells. Defined factors genes were amplified by PCR with specific primers of 9 arginines (R9) from recombinant plasmid pLL-hOCT4/pSox2/pMyc/pKlf4-EGFP (Yin et al. 2010 Prog. Biochem. Biophys. 37, 607–612) and inserted into prokaryotic expression vector pET-28a-EGFP. After DNA sequencing confirmation, the 4 recombinant plasmids were then transformed into BL21 strains, respectively. After IPTG induction, hOCT4/pSox2/pMyc/pKlf4-R9-EGFP fusion proteins were purified using Novagen His-Bind kit and confirmed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, respectively. Then, defined factors recombinant proteins were added into pig fetal fibroblasts (PFF) medium every 48 h to establish pig iPS cells. The results showed that purified hOCT4/pSox2/pMyc/pKlf4-R9-EGFP fusion proteins could enter into PFF efficiently, and most of them were located in nuclei. The PPF were subcultured in stem cell medium condition and treated with defined factors recombinant proteins for 6 cycles simultaneously; the clear-cut cell colonies were gradually derived. These cells had large translucent nuclei and a high nucleo:cytoplasmic ratio and were positive for AP, Oct4, and Nanog. Detailed characterisation of such induced cells is ongoing. This research would provide new ideas for the induction of porcine somatic cell reprogramming. Y. H. Zhang and H. G. Cao contributed equally. This work was supported by NSFC (30700574 30800784/c120103) and 973 (2009CB941004).

Abnormal hemostasis in a knock-in mouse carrying a variant of factor IX with impaired binding to collagen type IV

BACKGROUND

Factor IX binds to collagen type IV, but this binding has no known consequence.

OBJECTIVES

To determine the effect of reduced binding of FIX to collagen IV.

METHODS

We constructed and characterized 'knock-in' mice containing the mutation lysine 5 to alanine (K5A) in the Gla domain of their FIX. The K5A mutation dramatically reduced the affinity of FIX for collagen type IV, but had no measurable effect on platelet binding, phospholipid binding, or in vitro clotting activity. However, K5AFIX mice had a mild bleeding tendency, despite their in vitro clotting activity being normal. Hemostatic protection from delayed rebleeding was intermediate between wild-type and hemophilia B mice (which had no detectable clotting activity); moreover, survival of K5A FIX mice after nascent clot removal was dramatically improved as compared with hemophilia B mice. Importantly, there was no detectable difference between K5AFIX and wild-type mice in either a laser-induced thrombosis model or the chromogenic FIX activity assay. In contrast, after ferric chloride injury, which exposes collagen IV as well as other basement membrane proteins, intravital microscopy revealed that vessel occlusion was significantly slower in K5AFIX mice than in wild-type mice.

CONCLUSIONS

Our results indicate that the FIX molecule with decreased affinity for collagen IV has altered hemostatic properties in vivo and that the binding of FIX to collagen IV probably plays a significant functional role in hemostasis.

Transgene expression levels and kinetics determine risk of humoral immune response modeled in factor IX knockout and missense mutant mice

Immune responses leading to antibody-mediated elimination of the transgenic protein are a concern in gene replacement for congenital protein deficiencies, for which hemophilia is an important model. Although most hemophilia B patients have circulating non-functional but immunologically crossreactive factor IX (FIX) protein (CRM+ phenotype), inciting factors for FIX neutralizing antibody (inhibitor) development have been studied in crossreactive material-negative (CRM-) animal models. For this study, determinants of FIX inhibitor development were compared in hemophilia B mice, in which circulating FIX protein is absent (CRM- factor IX knockout (FIXKO) model) or present (CRM+ missense R333Q-hFIX model) modeling multiple potential therapies. The investigations compare for the first time different serotypes of adeno-associated virus (AAV) vectors (AAV2 and AAV1), each at multiple doses, in the setting of two different FIX mutations. The comparisons demonstrate in the FIXKO background (CRM- phenotype) that neither vector serotype nor vector particle number independently determine the inhibitor trigger, which is influenced primarily by the level and kinetics of transgene expression. In the CRM+ missense background, inhibitor development was never stimulated by AAV gene therapy or protein therapy, despite the persistence of lymphocytes capable of responding to FIX with non-inhibitory antibodies. This genotype/phenotype is strongly protective against antibody formation in response to FIX therapy.

Characterization of genomic regions directing the cell-specific expression of the mouse aldose reductase gene

Aldose reductase (AR), an enzyme implicated in the pathogenesis of diabetic complications, is highly expressed in such target organs of complications as the lens and peripheral nerve of experimental animals. In mouse, however, a very low level of the transcript was expressed in these tissues. To explore the unique expression pattern of AR in mice, genomic structure and upstream regions regulating the basal expression of the enzyme were determined. In NIH3T3 cells, a -1.1-kb upstream portion demonstrated the highest promoter activity. The ability to drive the luciferase reporter gene was reduced by 56% when the -1.1/-0.86-kb region was deleted. In Chinese hamster ovary (CHO) cells, deletion up to -0.67 kb did not affect basal promoter activity. The activity in CHO cells was reduced by 73% when the -0. 67/-0.24-kb region was deleted. These findings indicate that a genomic region directing the cell-specific transcription of the mouse AR gene exists.

The level of erythrocyte aldose reductase is associated with the severity of diabetic retinopathy

To examine whether the level of erythrocyte aldose reductase is a risk factor for the severity of diabetic retinopathy, the enzyme level in 97 non-insulin-dependent diabetes mellitus (NIDDM) patients was measured by the two-site enzyme-linked immunosorbent assay. Based on the results of fundus photography and biomicroscopy, the severity of retinopathy was classified among NIDDM patients of more than 10 years. The level of erythrocyte aldose reductase was significantly higher in the patients with active proliferative retinopathy than in those with nonproliferative or quiescent proliferative retinopathy. Multivariate logistic regression analysis demonstrated that the level of erythrocyte aldose reductase was an independent risk factor for active proliferative retinopathy (odds ratio, 1.28; 95% confidence interval, 1.01-1.61). The results suggest that a high level of erythrocyte aldose reductase in NIDDM patients may affect the prognosis of diabetic retinopathy. Patients with high enzyme levels would need to be closely followed up in the management of the retinal complication.

Presence of a closely related subgroup in the aldo-ketoreductase family of the mouse

Aldose reductase (alditol:NAD(P)+ 1-oxidoreductase), an enzyme implicated in the pathogenesis of various diabetic complications, catalyzes the reduction of a variety of aldehydes. From a mouse kidney library, we isolated aldose reductase cDNA that encodes a 316-amino-acid protein with approximately 97% identity to rat lens aldose reductase, approximately 69% identity to the mouse vas deferens protein and also approximately 69% identity to mouse fibroblast growth-factor-1-regulated protein. RNA-blot analysis demonstrated abundant expression of the enzyme transcript in the testis, skeletal muscle and kidney. However, a very low level of the transcript was detected in the sciatic nerve and lens, where abundant expression and involvement of the enzyme in diabetic complications were documented in other animals species. The isolated cDNA was expressed in Escherichia coli and the recombinant protein was purified to homogeneity by affinity chromatography and chromatofocusing. The expressed enzyme demonstrated reductase activity for various aldo sugars but not for the steroids. The enzyme reaction with DL-glyceraldehyde was, however, competitively inhibited by progesterone or 17 alpha-hydroxyprogesterone. The results not only indicate a unique tissue distribution and enzyme attribute of mouse aldose reductase, but also the presence of a closely related subgroup within the aldo-oxidoreductase superfamily in mouse tissues.

Enzyme immunoassay for erythrocyte aldose reductase

This two-site immunoassay measures erythrocyte aldose reductase by using monoclonal and polyclonal antibodies to recombinant human enzyme. Total incubation time is 2.5 h, and the limit of detection is &lt; 0.05 microgram/L. Analytical recovery tested with blood samples from healthy and diabetic individuals was 101-106%. Average CVs within and between assays were 3.7% and 4.8%, respectively. The enzyme content determined by this system correlated well with the activity of aldose reductase isolated from the same erythrocyte preparations. The amount of erythrocyte aldose reductase per milligram of hemoglobin was higher in women than in men (P &lt; 0.001), but no significant correlation was observed between the amount of enzyme and the age of the individuals. This assay method should provide useful clinical information to optimize administration of aldose reductase inhibitors for effective prevention and treatment of diabetic complications.

Enzyme immunoassay for erythrocyte aldose reductase

This two-site immunoassay measures erythrocyte aldose reductase by using monoclonal and polyclonal antibodies to recombinant human enzyme. Total incubation time is 2.5 h, and the limit of detection is < 0.05 microgram/L. Analytical recovery tested with blood samples from healthy and diabetic individuals was 101-106%. Average CVs within and between assays were 3.7% and 4.8%, respectively. The enzyme content determined by this system correlated well with the activity of aldose reductase isolated from the same erythrocyte preparations. The amount of erythrocyte aldose reductase per milligram of hemoglobin was higher in women than in men (P < 0.001), but no significant correlation was observed between the amount of enzyme and the age of the individuals. This assay method should provide useful clinical information to optimize administration of aldose reductase inhibitors for effective prevention and treatment of diabetic complications.

Proliferation of nasal epithelial and mesenchymal cells during primary palate formation

Proliferation of nasal epithelial and mesenchymal cells in mouse embryos was analyzed during primary palate formation using immunohistochemical demonstration of the thymidine analogue, 5-bromodeoxyuridine. Pulse labeling was employed to determine cell proliferation rates, with cell density of the nasal mesenchyme also being measured. To represent the entire nasal groove and prominences, four levels along the superior-inferior direction of three regions were utilized, i.e., the lateral and medial nasal prominences (LNP and MNP) and the bottom of the nasal groove. During the formation period, the labeling indices of the LNP and MNP epithelium decreased with respect to the development stage, whereas those of the bottom epithelium only slightly did. The epithelial cells in the prospective fusion area particularly showed decreased DNA synthesis in comparison with those in the nonfusing areas. In addition, the corresponding activity in the presumptive fusion area of the LNP epithelium was less than that in the MNP epithelium. The time at which a definitive decrease in the labeling index of the presumptive fusion area is believed to occur between tail somite (TS) stages TS5-7. A similar yet smaller decreasing tendency was observed in the labeling indices of the nasal mesenchyme. The cell density of the mesenchyme, however, slightly increased in all examined regions. Our results suggest that epithelial cell proliferation converts to a differentiation-type pattern, especially in the presumptive fusion area.(ABSTRACT TRUNCATED AT 250 WORDS)