Dynamics of childhood obesity in Hong Kong throughout the COVID-19 pandemic before and after the school closures: a 3-year longitudinal study.

OBJECTIVE: This study is to evaluate if there is any difference in the balance between incidence of and remission from overweight/obesity in Hong Kong school-age children before and during the COVID-19 pandemic over three years. METHODS: This is a retrospective longitudinal study that involved children aged 6-16 years from a database of the School Physical Fitness Award Scheme. RESULTS: 2765 students were longitudinally followed up for two years. The prevalence of childhood overweight/obesity was increased between the 2019 and 2021 academic years (P < 0.001). During the COVID-19 pandemic, the rate of obesity remission significantly reduced by 7.9 % (P = 0.003), at a background of a plateau of obesity among children and adolescents. CONCLUSIONS: Our study provides evidence on the impact of school closure and home confinement as a standard infection control measure for the prevention of COVID-19, which are likely to break the balance between incidence of and remission from childhood obesity.

Glycaemic control and microvascular complications among paediatric type 2 diabetes mellitus patients in Hong Kong at 2 years after diagnosis.

INTRODUCTION: Type 2 diabetes mellitus (T2DM) is becoming increasingly common among children and adolescents worldwide, including those in Hong Kong. This study analysed the characteristics and prevalence of microvascular complications among paediatric T2DM patients in Hong Kong at diagnosis and 2 years after diagnosis. METHODS: All patients aged <18 years who had been diagnosed with DM at public hospitals in Hong Kong were recruited into the Hong Kong Childhood Diabetes Registry. Data collected at diagnosis and 2 years after diagnosis were retrospectively retrieved from the Registry for patients diagnosed from 2014 to 2018. RESULTS: Median haemoglobin A1c (HbA1c) levels were 7.5% (n=203) at diagnosis and 6.5% (n=135) 2 years after diagnosis; 59.3% of patients achieved optimal glycaemic control (HbA1c level <7%) at 2 years. A higher HbA1c level at diagnosis was associated with worse glycaemic control at 2 years (correlation coefficient=0.39; P<0.001). The presence of dyslipidaemia (adjusted odds ratio [aOR]=3.19; P=0.033) and fatty liver (aOR=2.50; P=0.021) at 2 years were associated with suboptimal glycaemic control. Diabetic neuropathy and retinopathy were rare in our cohort, but 18.6% of patients developed microalbuminuria (MA) within 2 years after diagnosis. Patients with MA had a higher HbA1c level at 2 years (median: 7.2% vs 6.4%; P=0.037). Hypertension was a risk factor for MA at 2 years, independent of glycaemic control (aOR=4.61; P=0.008). CONCLUSION: These results highlight the importance of early diagnosis and holistic management (including co-morbidity management) for paediatric T2DM patients.

Health-related quality of life in paediatric spina bifida.

INTRODUCTION: The average incidence of spina bifida (SB) in Malaysia is 0.43 among 1,000 live births. The burden of the disease and its impact on the overall development and health though tremendously improved, remains significant. Therefore, current patient management strategies must include quality of life (QOL) measures. METHODS: This was a prospective, cross-sectional study on spina bifida children aged 5-20 years, attending the paediatric spina bifida clinics of Universiti Kebangsaan Malaysia Medical Centre Kuala Lumpur and Hospital Tuanku Jaanku Seremban. Scores were obtained using the validated disease specific Parkin QOL questionnaire. Univariate and multivariate analysis were used to investigate factors that were determinants for these outcomes. Results were expressed as beta coefficient and 95% confidence intervals (95%CI). RESULTS: A total of 54 children and adolescents aged between 5-20 years completed the questionnaires. Presence of neurogenic bowel (p=0.003), neurogenic bladder (p=0.041), shunt (p=0.044), non-ambulators (p=0.007) and being the only child in the family (p=0.037) were associated with lower QOL scores. Multivariate analysis showed presence of neurogenic bowel (ß=0.375, 95%CI: 0.00, 0.15) and being the only child in the family (ß=0.250, 95%CI: 0.04, 0.17) explained 22.1% of the variance in the QOL mean percentage scores. CONCLUSION: Being a single child in the family was the only socio-demographic variable associated with lower QOL scores. Although several clinical factors appeared to contribute significantly to QOL in spina bifida children, the presence of neurogenic bowel had the greatest impact.

Transition care readiness among patients in a tertiary paediatric department.

INTRODUCTION: A smooth transition of healthcare for young people with chronic illnesses from paediatric to adult healthcare services is important to ensure optimal outcome. At the moment, there are no standard guidelines to assess a patient's readiness to transfer care. METHODS: A cross-sectional study using a self-administered questionnaire, adapted from UNC (University of North Carolina) TRxANSITION self-assessment tool was conducted to evaluate patients' transition care readiness in paediatric haematology and paediatric diabetes clinic. RESULTS: A total of 80 patients (37 thalassaemia and 43 diabetes) with the mean age of 21.2 (SD±4.3) years, were recruited during the 3-month study period. Majority of the patients have basic knowledge regarding their medications, and were able to comply with their follow-up. The mean total score obtained by the respondents on this questionnaire was 15.3 (SD±3.59). Self-management skills and knowledge on disease were the two poorly scored section; with mean score of 3.78 (SD±1.38) and 4.28 (SD±1.20) respectively. Overall, only 21 (26.2%) respondents obtained high score (score above 75th percentile). Seventy-five percent of the respondents admitted that they were not ready for transfer to an adult healthcare service yet at the time of the study. CONCLUSION: We suggest that patients with high score should be prepared for transition to adult facility whereas those with a low score need to be identified to ensure provision of continuous education.

siRNA targeting the κ light chain constant region: preclinical testing of an approach to nonfibrillar and fibrillar light chain deposition diseases.

Treatment of light chain (LC) deposition diseases both nonfibrillar and fibrillar is aimed at eliminating LC production but success is limited. We report on the testing of an small interfering RNA pool targeting the κ LC constant region mRNA (si[IGKC]) designed for use against all κ plasma cell clones. To test for changes in κ LC message and protein production we used real-time PCR, immunoblot, intracellular mean fluorescence intensity and κ LC secretion by enzyme-linked immunosorbent assay. In vitro we employed 4 human cell lines that make κ LCs and 20 specimens of CD138-selected marrow plasma cells from patients with κ plasma cell diseases. In vivo, we used a murine flank plasmacytoma xenograft model. In vitro and in vivo, there were significant reductions in message and protein production by all modalities in all cell types despite diversity in variable region sequence. In addition, in clones producing intact immunoglobulin, caspase 3/7 activity with si[IGKC] was significantly increased compared with clones producing κ LC only, consistent with the triggering of a terminal unfolded protein response by excess unpaired heavy chains. In conclusion, si[IGKC] can significantly reduce κ LC production by κ plasma cells. Further preclinical development is needed to optimize delivery.

Altered cortical activation patterns associated with baroreflex unloading following 24 h of physical deconditioning.

Cardiovascular arousal is associated with patterned cortical activity changes. Head-down-tilt bed rest (HDBR) dimishes the baroreflex-mediated cardiac control. The present study tested the hypothesis that HDBR deconditioning would modify the forebrain organization for heart rate (HR) control during baroreflex unloading. Heart rate variability (HRV), blood pressure and plasma hormones were analysed at rest, whereas HR and cortical autonomic activation patterns (functional magnetic resonance imaging) were measured during graded and randomly assigned lower body negative pressure treatments (LBNP, -15 and -35 mmHg) both before (Pre) and after (Post) a 24 h HDBR protocol (study 1; n = 8). An additional group was tested before and following diuretic-induced hypovolaemia (study 2; n = 9; spironolactone, 100 mg day(-1) for 3 days) that mimicked the plasma volume lost during HDBR (-15% in both studies; P < 0.05). Head-down bed rest with hypovolaemia did not affect baseline HR, mean arterial pressure, HRV or plasma catecholamines. Head-down bed rest augmented the LBNP-induced HR response (P < 0.05), and this was associated with bed-rest-induced development of the following changes: (i) enhanced activation within the genual anterior cingulate cortex and the right anterior insular cortex; and (ii) deactivation patterns within the subgenual regions of the anterior cingulate cortex. Diuretic treatment (without HDBR) did not affect baseline HR and mean arterial pressure, but did reduce resting HRV and elevated circulating noradrenaline and plasma renin activity (P < 0.05). The greater HR response to LBNP following diuretic (P < 0.05) was associated with diminished activation of the right anterior insula. Our findings indicate that 24 h of HDBR minimized the impact of diuretic treatment on baseline autonomic and cardiovascular variables. The findings also indicate that despite the similar augmentation of HR responses to LBNP and despite similar pre-intervention cortical activation patterns, HDBR and diuretic treatment produced different effects on the cortical responses, with HDBR affecting anterior cingulate cortex and right insula regions, whereas diuretic treatment affected primarily the right insula alone, but in a direction that was opposite to HDBR. The data indicate that physical deconditioning can induce rapid functional changes within the cortical circuitry associated with baroreflex unloading, changes that are distinct from diuretic-induced hypovolaemia. The results suggest that physical activity patterns exert a rapid and notable impact on the cortical circuitry associated with cardiovascular control.

Ergonomic port placement in laparoscopic colorectal surgery.

AIM: Port placement in laparoscopic surgery has important ergonomic implications. A manipulation angle (MA) of 60° has been shown to maximize task efficiency. We calculated the MA used during various stages of both right hemicolectomy (RH) and high anterior resection (AR). METHOD: We compared two methods of port placement for each operation. RH-PP1 included ports in the left iliac fossa and left upper quadrant. RH-PP2 included ports suprapubically and in the left iliac fossa. We calculated the MA of each of these methods in mobilizing both the caecum and hepatic flexure. AR-PP1 included ports in the right iliac fossa and right upper quadrant. AR-PP2 included ports suprapubically and in the right iliac fossa. We calculated the MA of each of these methods in mobilizing the splenic flexure, descending-sigmoid junction and the recto-sigmoid junction. RESULTS: For RH-PP1, the mean MA for mobilizing the caecum and hepatic flexure was 38° and 52°, respectively. For RH-PP2, the mean MA for mobilising the caecum and hepatic flexure was 58° and 44°, respectively. For AR-PP1, the mean MA for mobilizing the splenic flexure, the descending-sigmoid junction and the recto-sigmoid junction was 77°, 41° and 18°, respectively. For AR-PP2, the mean MA for mobilizing the splenic flexure, the descending-sigmoid junction and the recto-sigmoid junction was 40°, 56° and 34°, respectively. CONCLUSION: There are no two port placements that will allow for an ideal MA at every stage of mobilization for either right- or left-sided resection.

Aerosol delivery of star polymer-siRNA nanoparticles as a therapeutic strategy to inhibit lung tumor growth.

Lung cancer is a major contributor to cancer-related death worldwide. siRNA nanomedicines are powerful tools for cancer therapeutics. However, there are challenges to overcome to increase siRNA delivery to solid tumors, including penetration of nanoparticles into a complex microenvironment following systemic delivery while avoiding rapid clearance by the reticuloendothelial system, and limited siRNA release from endosomes once inside the cell. Here we characterized cell uptake, intracellular trafficking, and gene silencing activity of miktoarm star polymer (PDMAEMA-POEGMA) nanoparticles (star nanoparticles) complexed to siRNA in lung cancer cells. We investigated the potential of nebulized star-siRNA nanoparticles to accumulate into orthotopic mouse lung tumors to inhibit expression of two genes [ßIII-tubulin, Polo-Like Kinase 1 (PLK1)] which: 1) are upregulated in lung cancer cells; 2) promote tumor growth; and 3) are difficult to inhibit using chemical drugs. Star-siRNA nanoparticles internalized into lung cancer cells and escaped the endo-lysosomal pathway to inhibit target gene expression in lung cancer cells in vitro. Nebulized star-siRNA nanoparticles accumulated into lungs and silenced the expression of ßIII-tubulin and PLK1 in mouse lung tumors, delaying aggressive tumor growth. These results demonstrate a proof-of-concept for aerosol delivery of star-siRNA nanoparticles as a novel therapeutic strategy to inhibit lung tumor growth.

Lrp6 Dynamic Expression in Tooth Development and Mutations in Oligodontia.

Genes associated with the WNT pathway play an important role in the etiology of tooth agenesis. Low-density lipoprotein receptor-related protein 6 encoding gene (LRP6) is a recently defined gene that is associated with autosomal dominant inherited tooth agenesis. Here, we aimed to identify novel LRP6 mutations in patients with tooth agenesis and investigate the significance of Lrp6 during tooth development. Using whole-exome sequencing, we identified 4 novel LRP6 heterozygous mutations (c.2292G>A, c.195dup, c.1095dup, and c.1681C>T) in 4 of 77 oligodontia patients. Notably, a patient who carried a nonsense LRP6 mutation (c.2292G>A; p.W764*) presented a hypohidrotic ectodermal dysplasia phenotype. Preliminary functional studies, including bioinformatics analysis and TOP-/FOP-flash reporter assays, demonstrated that the activation of WNT/ß-catenin signaling was compromised as a consequence of LRP6 mutations. RNAscope in situ hybridization revealed dynamic and special changes of Lrp6 expression during murine tooth development from E11.5 to E16.5. It was noteworthy that Lrp6 was specifically expressed in the epithelium at E11.5 to E13.5 but was expressed in both dental epithelium and dental papilla from E14.5 and persisted in both tissues at later stages. Our study broadens the mutation spectrum of human tooth agenesis and is the first to identify a LRP6 mutation in patients with hypohidrotic ectodermal dysplasia and reveal the dynamic expression pattern of Lrp6 during tooth development. Information from this study is conducive to understanding the functional significance of Lrp6 on the biological process of tooth development.

Efficacy of a Comprehensive Dysphagia Intervention Program Tailored for the Residents of Nursing Homes.

Oropharyngeal dysphagia is a widespread condition in older people and thus poses a serious health threat to the residents of nursing homes. The management of dysphagia relies mainly on compensatory strategies, such as diet and environmental modification. This study investigated the efficacy of an intervention program using a single-arm interventional study design. Twenty-two participants from nursing homes were included and had an average of 26 hours of intervention, including oromotor exercises, orosensory stimulation and exercises to target dysphagia and caregiver training. Four of the 22 participants exhibited improvement in functional oral intake scale (FOIS) but was not statistically significant as a group. All oromotor function parameters, including the range, strength, and coordination of movements, significantly improved. These results indicate that this intervention program could potentially improve the oromotor function, which were translated into functional improvements in some participants' recommended diets. The validity of this study could be improved further by using standardized swallowing and feeding assessment methods or an instrumental swallowing assessment.

Radiomic Phenotypes Distinguish Atypical Teratoid/Rhabdoid Tumors from Medulloblastoma.

BACKGROUND AND PURPOSE: Atypical teratoid/rhabdoid tumors and medulloblastomas have similar imaging and histologic features but distinctly different outcomes. We hypothesized that they could be distinguished by MR imaging-based radiomic phenotypes. MATERIALS AND METHODS: We retrospectively assembled T2-weighted and gadolinium-enhanced T1-weighted images of 48 posterior fossa atypical teratoid/rhabdoid tumors and 96 match-paired medulloblastomas from 7 institutions. Using a holdout test set, we measured the performance of 6 candidate classifier models using 6 imaging features derived by sparse regression of 900 T2WI and 900 T1WI Imaging Biomarker Standardization Initiative-based radiomics features. RESULTS: From the originally extracted 1800 total Imaging Biomarker Standardization Initiative-based features, sparse regression consistently reduced the feature set to 1 from T1WI and 5 from T2WI. Among classifier models, logistic regression performed with the highest AUC of 0.86, with sensitivity, specificity, accuracy, and F1 scores of 0.80, 0.82, 0.81, and 0.85, respectively. The top 3 important Imaging Biomarker Standardization Initiative features, by decreasing order of relative contribution, included voxel intensity at the 90th percentile, inverse difference moment normalized, and kurtosis-all from T2WI. CONCLUSIONS: Six quantitative signatures of image intensity, texture, and morphology distinguish atypical teratoid/rhabdoid tumors from medulloblastomas with high prediction performance across different machine learning strategies. Use of this technique for preoperative diagnosis of atypical teratoid/rhabdoid tumors could significantly inform therapeutic strategies and patient care discussions.

Induction of B cell hyperplasia in simian immunodeficiency virus-infected rhesus macaques with the simian homologue of Kaposi's sarcoma-associated herpesvirus.

A simian homologue of Kaposi's sarcoma-associated herpesvirus (KSHV), the eighth human herpesvirus (HHV8), was isolated from a simian immunodeficiency virus (SIV)-infected rhesus macaque (Macaca mulatta) that developed a multicentric lymphoproliferative disorder (LPD). This simian rhadinovirus is genetically similar to a recently described rhesus rhadinovirus (RRV) (Desrosiers, R.C., V.G. Sasseville, S.C. Czajak, X. Zhang, K.G. Mansfield, A. Kaur, R.P. Johnson, A.A. Lackner, and J.U. Jung. 1997. J. Virol. 71:9764-9769) and is designated RRV 17577. RRV 17577 was experimentally inoculated into rhesus macaques with and without SIV(mac239) infection to determine if RRV played a role in development of the LPD observed in the index case. In contrast to control animals inoculated with SIV(mac239) or RRV alone, two animals coinfected with SIV(mac239) and RRV 17577 developed hyperplastic LPD resembling the multicentric plasma cell variant of Castleman's disease, characterized by persistent angiofollicular lymphadenopathy, hepatomegaly, splenomegaly, and hypergammaglobulinemia. Hypergammaglobulinemia was associated with severe immune-mediated hemolytic anemia in one RRV/SIV-infected macaque. Both RRV/SIV-infected macaques exhibited persistent RRV viremia with little or no RRV-specific antibody response. The macaques inoculated with RRV alone displayed transient viremia followed by a vigorous anti-RRV antibody response and lacked evidence of LPD in peripheral blood and lymph nodes. Infectious RRV and RRV DNA were present in hyperplastic lymphoid tissues of the RRV/SIV-infected macaques, suggesting that lymphoid hyperplasia is associated with the high levels of replication. Thus, experimental RRV 17577 infection of SIV-infected rhesus macaques induces some of the hyperplastic B cell LPDs manifested in AIDS patients coinfected with KSHV.

Epithelial Wnt10a Is Essential for Tooth Root Furcation Morphogenesis.

WNT10A (Wingless-type MMTV integration site family, member 10A) plays a crucial role in tooth development, and patients with biallelic WNT10A mutation and mice lacking Wnt10a show taurodontism. However, whether epithelial or mesenchymal WNT10A controls the initiation of the root furcation formation remains unclear, and the functional significance of WNT10A in regulating root morphogenesis has not been clarified. Here, we investigated how Wnt10a affects tooth root development by generating different tissue-specific Wnt10a conditional knockout mice. Wnt10a knockout in the whole tissue (EIIa-Cre;Wnt10aflox/flox) and in dental epithelium (K14-Cre;Wnt10aflox/flox) led to an absence of or apically located root furcation in molars of mice, a phenotype that resembled taurodontism. An RNAscope analysis showed that the dynamic epithelial and mesenchymal Wnt10a expression pattern occurred during root development. Immunofluorescent staining of E-cadherin and EdU revealed decreased epithelial cell proliferation at the cervical region of the molar in K14-Cre;Wnt10aflox/flox mice at postnatal day 0 (PN0), just before the initiation of root morphogenesis. Interestingly, we found increased pulpal mesenchymal cell proliferation in the presumptive root furcating region of the molar in K14-Cre;Wnt10aflox/flox mice at PN4 and PN7. RNA-seq indicated that among the Wnt ligands with high endogenous expression levels in molars, Wnt4 was increased after epithelial knockout of Wnt10a. The RNAscope assay confirmed that the expression of Wnt4 and Axin2 in the dental papilla of the presumptive root furcating region, where dental pulp overgrowth occurred, was increased in K14-Cre;Wnt10aflox/flox molars. Furthermore, after suppression of the elevated Wnt4 level in K14-Cre;Wnt10aflox/flox molars by Wnt4 shRNA adenovirus and kidney capsule grafts, the root furcation defect was partially rescued. Taken together, our study provides the first in vivo evidence that epithelial Wnt10a guides root furcation formation and plays a crucial role in controlling the organized proliferation of adjacent mesenchymal cells by regulating proper Wnt4 expression during root furcation morphogenesis.

Viral interleukin-6 encoded by rhesus macaque rhadinovirus is associated with lymphoproliferative disorder (LPD).

BACKGROUND: Rhesus macaques (RM) co-infected with simian immunodeficiency virus (SIV) and rhesus macaque rhadinovirus (RRV) develop abnormal cellular proliferations characterized as extra-nodal lymphoma and retroperitoneal fibromatosis (RF). RRV encodes a viral interleukin-6 (vIL-6), much like Kaposi's sarcoma-associated herpesvirus, and involvement of the viral cytokine was examined in proliferative lesions. METHODS: Formalin fixed tissue from RM co-infected with SIV and RRV were analyzed for RRV genomes by in situ hybridization and RRV vIL-6 expression by immunofluorescence analysis. RESULTS: In situ hybridization analysis indicated that RRV is present in both types of lesions. Immunofluorescence analysis of different lymphomas and RF revealed positive staining for vIL-6. Similarly to KS, RF lesion is positive for vimentin, CD117 (c-kit), and smooth muscle actin (SMA) and contains T cell, B cell and monocytes/macrophage infiltrates. CONCLUSIONS: Our data support the idea that vIL-6 may be critical to the development and progression of lymphoproliferative disorder in RRV/SIV-infected RM.

Scan-directed unilateral neck exploration for primary hyperparathyroidism: eight-year results from a regional hospital.

OBJECTIVE: To determine the results of scan-directed unilateral neck exploration for primary hyperparathyroidism. DESIGN: Retrospective study. SETTING: Regional hospital, Hong Kong. PATIENTS: Patients who underwent parathyroid surgery for primary hyperparathyroidism between January 2000 and December 2007 were included. MAIN OUTCOME MEASURES: The demographic, imaging, biochemical, and pathological data, as well as surgical outcomes were analysed according to the treatment received. RESULTS: A total of 78 patients were included in this study; 65 underwent unilateral neck exploration with image guidance by ultrasonography or technetium Tc99m sestamibi scan. The scan sensitivity for localising the side of the lesion was 66% for ultrasound scans, 71% for technetium Tc99m sestamibi scans, and 85% for both scans used in combination. Pathological analysis showed that 95% (74/78) of the patients had a single parathyroid adenoma, two had hyperplasia of four glands, one had a double adenoma, and one a parathyroid carcinoma. Among the patients undergoing scan-directed unilateral neck exploration, one defaulted follow-up, while the remaining 64 patients achieved normal calcium levels at a median follow-up of 6 months. CONCLUSION: Scan-directed unilateral neck exploration is a safe alternative form of treatment for patients with primary hyperparathyroidism, with a cure rate similar to conventional therapy.

Dilated common bile ducts mimicking choledochal cysts in ketamine abusers.

Substance abuse is a major health and social problem among Hong Kong youth and ketamine is the drug most commonly abused. Ketamine abuse is associated with a series of side-effects that include hallucination, nausea, vomiting, elevation of blood pressure, and urinary bladder dysfunction. Here we report three cases of ketamine abuse in which the abusers presented with recurrent epigastric pain and dilated common bile ducts that mimicked choledochal cysts on imaging. The dilated biliary tree may occur more frequently than was once assumed.

Malignant hypertension in a child with phakomatosis pigmentovascularis type II b.

UNLABELLED: Phakomatosis pigmentovascularis (PPV) is a rare congenital syndrome characterized predominantly by cutaneous vascular malformations and pigmentary naevi. The most frequently reported form, Type II b, is associated with systemic involvement. Sturge-Weber Syndrome (SWS) with concomitant glaucoma, Klippel-Trenaunay Syndrome (KTS) and naevus of Ota have been frequently described, but there have only been two case reports with asymptomatic renal anomalies. CONCLUSION: We report the first case of PPV associated with SWS and naevus of Ota presenting with malignant hypertension secondary to bilateral renal artery stenosis. This case raises the possibility that the phakomatoses are not distinct entities but a spectrum of overlapping neurocutaneous, vascular and renal features.

Congenital hepatic fibrosis in a child with autosomal dominant polycystic kidney disease.

The association of congenital hepatic fibrosis (CHF) with autosomal recessive polycystic kidney disease (ARPKD) is well known and occurs in approximately 50% of cases. However the association of CHF with autosomal dominant polycystic kidney disease (ADPKD) is less well known and less well documented. We report a child with neonatal onset of hypertension due to ADPKD who later develops portal hypertension due to CHF in childhood. A review of this rare association follows.

Nine Novel PAX9 Mutations and a Distinct Tooth Agenesis Genotype-Phenotype.

Tooth agenesis is one of the most common developmental anomalies affecting function and esthetics. The paired-domain transcription factor, Pax9, is critical for patterning and morphogenesis of tooth and taste buds. Mutations of PAX9 have been identified in patients with tooth agenesis. Despite significant progress in the genetics of tooth agenesis, many gaps in knowledge exist in refining the genotype-phenotype correlation between PAX9 and tooth agenesis. In the present study, we complete genetic and phenotypic characterization of multiplex Chinese families with nonsyndromic (NS) tooth agenesis. Direct sequencing of polymerase chain reaction products revealed 9 novel (c.140G>C, c.167T>A, c.332G>C, c.194C>A, c.271A>T, c.146delC, c.185_189dup, c.256_262dup, and c.592delG) and 2 known heterozygous mutations in the PAX9 gene among 120 probands. Subsequently, pedigrees were extended, and we confirmed that the mutations co-segregated with the tooth agenesis phenotype (with exception of families in which DNA analysis was not available). In 1 family ( n = 6), 2 individuals harbored both the PAX9 c.592delG mutation and a heterozygous missense mutation (c.739C>T) in the MSX1 gene. Clinical characterization of families segregating a PAX9 mutation reveal that all affected individuals were missing the mandibular second molar and their maxillary central incisors are most susceptible to microdontia. A significant reduction of bitter taste perception was documented in individuals harboring PAX9 mutations ( n = 3). Functional studies revealed that PAX9 haploinsufficiency or a loss of function of the PAX9 protein underlies tooth agenesis.

Gene expression of human DNA polymerase alpha during cell proliferation and the cell cycle.

We studied the expression of the human DNA polymerase alpha gene during cell proliferation, during cell progression through the cell cycle, and in transformed cells compared with normal cells. During the activation of quiescent cells (G0 phase) to proliferate (G1/S phases), the steady-state mRNA levels, rate of synthesis of nascent polymerase protein, and enzymatic activity in vitro exhibited a substantial and concordant increase prior to the peak of in vivo DNA synthesis. In transformed cells, the respective values were amplified greater than 10-fold. In actively growing cells separated into discrete stages of the cell cycle by counterflow elutriation or by mitotic shakeoff, levels of steady-state transcripts, translation rates, and enzymatic activities of polymerase alpha were constitutively and concordantly expressed at all stages of the cell cycle, with only a moderate elevation prior to the S phase and a slight decline in the G2 phase. These findings support the conclusion that the regulation of human DNA polymerase alpha gene expression is at the transcriptional level and strongly suggest that the regulatory mechanisms that are operative during the entrance of a cell into the mitotic cycle are fundamentally different from those that modulate polymerase alpha expression in continuously cycling cells.