Biomedical subjects

J M Chow

Publications and source records attributed to J M Chow.

60 records · Page 4Linked to original sources

PubMedDate not supplied

Dynamic computerized tomography in the assessment of hemangioma.

Three hemangiomas of the face and orbit are studied with dynamic computerized tomography (CT). This noninvasive technique has the advantage of simultaneous bone and soft tissue visualization at the time of peak contrast enhancement, and it precludes the potential complications of arteriography and biopsy. The hemangiomas are precisely delineated with intense contrast; the sharp peak and rapid uninterrupted runoff of the computer-generated plot of contrast concentration (CT number) versus time is characteristic of this lesion. It is suggested that the progress of hemangioma involution may be documented by the change in contrast distribution in sequential dynamic CT studies. Dynamic CT is recommended for the evaluation of head and neck vascular tumors.

Adult↗

PubMedDate not supplied

Acoustic neuroma presenting as sudden hearing loss.

Sudden hearing loss occurs as the initial symptom in 1 to 9 per cent of all acoustic neuromas. A case of an acoustic neuroma presenting with sudden hearing loss is described. In this case, the hearing thresholds returned to normal. To the authors' knowledge, this is the first case in which an acoustic neuroma presenting with sudden hearing loss exhibited a return to normal thresholds. This suggests that such tumors may have an initial reversible effect on hearing thresholds.

Acute Disease↗

PubMedDate not supplied

The fallibility of diagnostic tests for sexually transmitted diseases: the impact of behavioral and epidemiologic studies.

OBJECTIVES: Analysis of sexually transmitted disease (STD) data to identify specific behaviors and risk factors often fails to take into account the misclassification of disease by a less than perfect diagnostic test. The authors consider here how a diagnostic test's performance profile can introduce misclassification and thereby bias measures of association. METHODS: The authors used hypothetical data relating to diagnostic tests for Chlamydia trachomatis infections and oral contraceptive use to determine odds ratio estimates given a range of sensitivity, specificity, prevalence of infection, and sample size. RESULTS: Lower specificity in a diagnostic test can result in an underestimation of a risk factor's association with an infection. This bias is particularly severe in low prevalence populations. Use of a diagnostic test with low specificity also will increase the sample size needed to demonstrate the association and, thus, the cost of such surveys. CONCLUSIONS: Diagnostics tests for sexually transmitted diseases have less than perfect sensitivity and specificity, which affects the validity of analyses of factors associated with sexually transmitted diseases. Analyses done using low prevalence populations and/or small sample sizes may underestimate the magnitude of effect in retrospective studies and clinical trials of behavioral interventions aimed at reducing sexually transmitted disease risk.

Chlamydia Infections↗

PubMedDate not supplied

Chlamydial serology among patients with tubal factor infertility and ectopic pregnancy in Alexandria, Egypt.

BACKGROUND AND OBJECTIVES: Little is known about the role of Chlamydia trachomatis in the etiology of tubal factor infertility and ectopic pregnancy in Egypt. GOAL OF THIS STUDY: To assess the association between past chlamydial infection, tubal factor infertility, and ectopic pregnancy in an Egyptian population. STUDY DESIGN: This report consists of two concurrent case-control studies. First, 51 patients with tubal factor infertility were compared with 48 healthy subjects who did not have tubal factor infertility and 53 pregnant subject subjects. Second, 66 patients with ectopic pregnancy were compared with 51 pregnant control subjects. RESULTS: Geometric mean titers for Chlamydia trachomatis were higher among patients with tubal factor infertility and ectopic pregnancy, and they were more likely to have high antichlamydial titers (> or = 1:128 immunoglobulin G). Serum titer was significantly correlated with histologic evidence of salpingitis among the patients with an ectopic pregnancy. CONCLUSION: Our findings, similar to those from Western societies, suggest that among Egyptian women, prior chlamydial infection is associated with an increased risk of tubal factor infertility and possibly ectopic pregnancy.

Adult↗

PubMedDate not supplied

Correlation of middle meatal and maxillary sinus cultures in acute maxillary sinusitis.

Cultures obtained from the middle meatus have been used frequently in the past to direct therapy in patients with acute maxillary sinusitis. However, no convincing data have been published to indicate that middle meatal cultures accurately represent the bacterial flora within the maxillary sinus. The hypothesis of this experiment is that bacteria obtained by directed middle meatal cultures qualitatively and quantitatively correlate with cultures taken by maxillary sinus puncture. Acute sinusitis was induced by injecting 10(8) colony-forming units of bacteria directly into the maxillary sinuses of rabbits in which the ostia were occluded with cotton packs. Eight animals were injected with Staphylococcus aureus, eight with Haemophilus influenzae, and eight with Streptococcus pneumoniae. The packs were removed after 3 days, and specimens were obtained from the middle meatus in the region of the maxillary sinus ostium, and from the maxillary sinus, 1 day later. The contralateral maxillary sinuses of six of the animals were injected with normal saline and served as controls. There was a 100% correlation rate between cultures of specimens obtained from the maxillary sinus and from the middle meatus in all 24 animals. In addition, the quantitative counts from the middle meatus and the maxillary sinus correlated. Control animals showed no bacterial growth from either the middle meatus or the maxillary sinus. These results show that, in an animal model of acute sinusitis, cultures of specimens from the middle meatus reflect the contents of the maxillary sinus.

Acute Disease↗

PubMedDate not supplied

Endoscopic transsphenoidal biopsy of the sphenoid and clival mass.

Abnormalities of the clivus/skull base occur most commonly as a result of disease spread from adjacent structures, but can also occur from primary involvement of the clivus. Traditionally, definitive diagnosis was made by CT guided biopsy or craniotomy. However, lesions can occur in this area that are not amenable to CT guided biopsy or craniotomy. Endoscopic transsphenoidal surgery can provide a safe method for obtaining a clival biopsy, debulking of tumor tissue, or definitive treatment without the morbidity and mortality of a craniotomy. This study was designed to describe our experience with the endoscopic approach to the skull base and clivus via the sphenoid sinus. A series of seven patients underwent endoscopic transsphenoidal biopsy of a sphenoid clival lesion. All patients avoided anticipated craniotomy, and definitive pathology was obtained in five of six patients. In two cases, excisional biopsy proved to be therapeutic. There were no deaths, and major complications included one CSF leak and one intraoperative hemorrhage, both of which were controlled immediately. The experience gained with these patients demonstrates the feasibility and safety of this new application of endoscopic sinus surgery for the diagnosis and possible treatment of lesions of the sphenoid and clivus.

Adult↗