Biomedical subjects

H Kwok

Publications and source records attributed to H Kwok.

4 recordsLinked to original sources

PubMed2000

Preoperative staging of rectal cancer.

With the widespread introduction of preoperative radiotherapy for rectal cancer and the development of transanal endoscopic microsurgery for selected early lesions, preoperative radiological staging of these tumours has taken on increasing importance. This study is a systematic review to evaluate computed tomography (CT), endorectal sonography (ES) and magnetic resonance imaging (MRI) as preoperative staging modalities in rectal cancer. A Medline-based search identifying studies using CT, ES, or MRI in preoperative staging of rectal cancer between 1980 and 1998 was undertaken. The list of papers was supplemented by extensive cross-checking of citation lists. Studies were included if they met predetermined criteria. Data from the accepted studies were entered into pooled tables comparing radiological and pathological staging results for each modality both in determining bowel wall penetration and involvement of lymph nodes. Accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio were determined for the pooled results. Eighty-three studies from 78 papers including 4,897 patients met the inclusion criteria. In determining the wall penetration of the tumour the values for sensitivity for CT, ES, MRI and MRI with endorectal coil were 78%, 93%, 86% and 89%; for specificity 63%, 78%, 77% and 79%; and for accuracy 73%, 87%, 82% and 84%, respectively. In determining the nodal involvement by tumour the sensitivity values for CT, ES, MRI and MRI with endorectal coil 52%, 71%, 65% and 82%; for specificity 78%, 76%, 80% and 83%; and for accuracy 66%, 74%, 74% and 82%, respectively. MRI with an endorectal coil is the single investigation that most accurately predicts pathological stage in rectal cancer.

Humans↗

PubMed2000

Development of the ventilatory response to hypoxia in Swiss CD-1 mice.

We examined developmental changes in breathing pattern and the ventilatory response to hypoxia (7.4% O(2)) in unanesthetized Swiss CD-1 mice ranging in age from postnatal day 0 to 42 (P(0)-P(42)) using head-out plethysmography. The breathing pattern of P(0) mice was unstable. Apneas were frequent at P(0) (occupying 29 +/- 6% of total time) but rare by P(3) (5 +/- 2% of total time). Tidal volume increased in proportion to body mass ( approximately 10-13 ml/kg), but increases in respiratory frequency (f) (55 +/- 7, 130 +/- 13, and 207 +/- 20 cycles/min for P(0), P(3), and P(42), respectively) were responsible for developmental increases in minute ventilation (690 +/- 90, 1,530 +/- 250, and 2,170 +/- 430 ml. min(-1). kg(-1) for P(0), P(3), and P(42), respectively). Between P(0) and P(3), increases in f were mediated by reductions in apnea and inspiratory and expiratory times; beyond P(3), increases were due to reductions in expiratory time. Mice of all ages showed a biphasic hypoxic ventilatory response, which differed in two respects from the response typical of most mammals. First, the initial hyperpnea, which was greatest in mature animals, decreased developmentally from a maximum, relative to control, of 2.58 +/- 0.29 in P(0) mice to 1. 32 +/- 0.09 in P(42) mice. Second, whereas ventilation typically falls to or below control in most neonatal mammals, ventilation remained elevated relative to control throughout the hypoxic exposure in P(0) (1.73 +/- 0.31), P(3) (1.64 +/- 0.29), and P(9) (1. 34 +/- 0.17) mice but not in P(19) or P(42) mice.

Aging↗

PubMed1999

Phrenoesophageal ligament re-visited.

The phrenoesophageal ligament, attaching the esophagus to the diaphragm, has been given little emphasis in anatomy teaching. This study was undertaken to examine the macroscopic and microscopic structure of the phrenoesophageal ligament. The results indicate that the ligament is a distinct structure bridging the space between the esophageal wall and the margins of the esophageal hiatus. This ligament appears to arise from both the endothoracic fascia and the transversalis fascia and is composed of abundant collagen and elastic lamellae. Toward the wall of the esophagus, the ligament divides into a prominent upper leaf and an ill-defined lower leaf before inserting into the wall of the esophagus. Histological study reveals that the ligament has a substantial and deep insertion into the wall of the esophagus. It appears that the ligament plays an important role in anchoring the lower esophagus and maintaining gastroesophageal competence.

Cadaver↗

PubMed1993

Some computer-based decision support tools for the rehabilitation manager.

The recent introduction of the Management Information System (MIS) guidelines has sparked much interest among health care institutions across Canada regarding proper approaches to the recording and interpretation of various financial and workload indicators. While the benefits of the MIS guidelines are widely acknowledged, much less attention has been directed to how departmental managers can analyze and make use of the vast amount of information generated. In this paper we attempt to review some of the computer-based decision-support tools that may be useful to the manager of the rehabilitation services department in analyzing the various MIS data that are collected. The data are assumed to be available through a computerized rehabilitation information system which includes workload measures. The quantitative models reviewed in this paper include basic descriptive statistics, deviation, trend and what-if-analysis and graph-plotting. Although the use of such tools can assist the rehabilitation manager in the routine decision-making process, it is very important that we ask the right questions and employ the proper model to make the most rational and best decision. In this respect, ongoing training in general problem-solving skills, decision-making processes, and use of computer-based decision-support tools may be very beneficial.

Canada↗