[show abstract][hide abstract] ABSTRACT: To evaluate the influence of meteorological factors on the onset of aneurysmal subarachnoid haemorrhage in Hong Kong.
Retrospective review of prospectively collected data.
University teaching hospital, Hong Kong.
A total of 135 consecutive patients with acute aneurysmal subarachnoid haemorrhage presenting to the hospital within 48 hours after ictus from October 2002 to October 2006.
Occurrence of aneurysmal subarachnoid haemorrhage in relation to daily changes in atmospheric pressure, temperature, and humidity.
The peak incidence of aneurysmal subarachnoid haemorrhage occurred in winter (December to February), especially January. The mean (+/-standard deviation) daily atmospheric pressure change was significantly higher on days with aneurysmal subarachnoid haemorrhage onset as opposed to days without (1.75+/-1.47 hPa vs 1.48+/-1.28 hPa; P=0.032).
A seasonal variation and relationship to atmospheric pressure change in aneurysmal subarachnoid haemorrhage was noted in the current study carried out in Hong Kong. The mechanism linking atmospheric pressure change and aneurysmal rupture remained to be explored.
Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine 05/2009; 15(2):85-9.
[show abstract][hide abstract] ABSTRACT: This case report describes the treatment of a 12-year-old Chinese boy with a Class II skeletal profile, an extreme overjet, and a retrusive mandible. The patient was teased at school because of his appearance, and he was experiencing negative psychosocial impacts, including shyness and falling grades. Orthodontic treatment had a positive psychosocial impact on his life over a period of 10 years. The advantages of using functional appliances are highlighted in this report.
American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 11/2006; 130(4):540-8. · 1.33 Impact Factor
[show abstract][hide abstract] ABSTRACT: The purposes of this study were to quantify the number of replicating mesenchymal cells and to correlate it with the amount of new bone formed in the glenoid fossa during stepwise advancement. We randomly divided 250 female Sprague-Dawley rats, 35 days old, into 10 control groups (n = 5) and 20 experimental groups (n = 10). Fifty rats from the stepwise experimental group received initial advancement of 2 mm and another 1.5 mm of advancement on day 30 by the addition of veeners. On days 3, 7, 14, 21, 30, 33, 37, 44, 51, and 60, the rats were killed. One hour before that, the rats were injected with bromodeoxyuridine (BrdU) intravenously. We cut 7-microm tissue sections through the glenoid fossa sagittally and stained them with anti-BrdU antibody to evaluate the number of replicating mesenchymal cells. During the first advancement, the number of replicating cells in the posterior region of the glenoid fossa showed a significant increase compared with natural growth, but a significant decrease compared with 1-step advancement. On the second advancement, however, an increase in the number of replicating cells was observed on day 37 with a subsequent and significant increase in bone formation on day 44. Mandibular advancement conducted in a stepwise fashion increases the number of replicating mesenchymal cells in the glenoid fossa. However, a minimum threshold of strain must first be exceeded before these mesenchymal cells can differentiate to ultimately form new bone.
American Journal of Orthodontics and Dentofacial Orthopedics 06/2003; 123(5):521-6. · 1.46 Impact Factor
[show abstract][hide abstract] ABSTRACT: The purpose of this study was to identify and quantify the temporal sequence of replicating mesenchymal cells during natural growth and mandibular advancement in the condyle and the glenoid fossa. One hundred fifty 35-day-old female Sprague-Dawley rats were randomly divided into 10 experimental groups (10 rats each) and 10 control groups (5 rats each). The experimental groups were fitted with appliances that positioned the mandible forward. One hour before the rats were killed, bromodeoxyuridine (BrdU) was intravenously injected into them. Sections were cut and stained with anti-BrdU antibody to evaluate the number of replicating mesenchymal cells. Cellular uptake of BrdU was quantified with the Leica Qwin (Leica Microsystem Imaging Solutions, Cambridge, United Kingdom) system. The results showed that the numbers of replicating mesenchymal cells during natural growth were highest in the posterior region of the condyle and the anterior region of the glenoid fossa. In the experimental groups, the posterior region had the highest number of replicating cells for both the condyle and the glenoid fossa, with the condyle having 2 to 3 times more replicating cells than the glenoid fossa. The number of replicating mesenchymal cells, which is genetically controlled, influences the growth potential of the condyle and the glenoid fossa. Mandibular protrusion leads to an increase in the number of replicating cells in the temporomandibular joint. Individual variations in the response to growth modification therapy could be a result of the close correlation between mesenchymal cell numbers and growth.
American Journal of Orthodontics and Dentofacial Orthopedics 02/2003; 123(1):49-57. · 1.46 Impact Factor
[show abstract][hide abstract] ABSTRACT: ConclusionsA seasonal variation and relationship to atmospheric pressure change in aneurysmal subarachnoid haemorrhage was noted in the current study carried out in Hong Kong. The mechanism linking atmospheric pressure change and aneurysmal rupture remained to be explored.