Rigid contact lens decentration: a risk factor for corneal warpage

Clinically significant contact lens induced corneal warpage is seen in a small proportion of soft and rigid contact lens wearers. Previous studies using the keratometer have found no correlation between the fit of the lens and the induced topographic changes. In this study, using computer-assisted topographic analysis, seven eyes (four patients) with rigid contact lens-induced corneal warpage were noted to have topographic abnormalities that correlated with the decentered resting position of the contact lens on the cornea. The warpage topography for each of these corneas was characterized by a relative flattening of the cornea underlying the resting position of the contact lens. Lenses that rode high, for example, produced flattening superiorly and resulted in a relatively steeper contour inferiorly that simulated the topography of early keratoconus patients who had not worn contact lenses. After discontinuing contact lenses the corneal topography returned to a normal pattern in five eyes. Two eyes retained asymmetry that is not characteristic of normal corneas. Up to 6 months was required for the corneas to return to a stable topography after contact lens wear was discontinued.     

The relationship between neuropsychological function and brain damage detected by neuroimaging after closed head injury

Studies relating neuropsychology and structural neuroimaging after closed head injury are reviewed. Particular attention is given to the question of the relative contribution of focal and diffuse damage to neuropsychological impairment. The evidence currently available emphasizes the importance of diffuse damage in closed head injury. Diffuse damage is not equally distributed in the brain, and the review suggests three axes that are relevant for neuropsychological function: (1) damage may be unilateral or bilateral, (2) damage is characteristically greater in anterior regions than posterior regions, and (3) damage shows a centripetal gradient. A large gap remains between the emergent generalizations concerning head injury and reliable neuropsychological interpretation of scans from individual patients.     

Serum measurements of soluble CD23 in HIV infection.

A gradual reduction in cell-mediated immunity is thought to occur with the progression of human immunodeficiency virus (HIV) infection. This suggests a selective attrition of the Th1 subset. The regulation of the soluble form of the low-affinity receptor for IgE (sCD23) by the opposing actions of interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) allows the assessment of the overall balance of Th1 to Th2 activity in a given disease. In order to investigate this further we employed an enhanced chemiluminescent ELISA to analyse serum levels of sCD23 in male subjects with and without HIV infection. Serum levels of sCD23 were similar in 34 HIV seronegative homosexuals, 39 homosexuals with asymptomatic HIV infection, 27 homosexuals with acquired immune deficiency syndrome (AIDS) and 20 healthy controls. This suggests that HIV has no predilection for either the Th1 or Th2 subsets of CD4 T cells.     

The chief medical residency in Canada: comparison of opinions between physicians-in-chief and chief medical residents.

We conducted a survey of physicians-in-chief (PCs) and chief medical residents (CMRs) in training programs throughout Canada to determine their attitudes toward the need for and role of CMRs in Canada and to rate the importance of CMR duties and attributes. Forty-three hospitals with 5 to 126 house staff in all eight provinces with medical schools were surveyed; 36 PCs (84%) and 29 CMRs (67%) returned a completed questionnaire. Compared with the CMRs the PCs preferred more prior training (p less than 0.03), estimated as significantly less the time spent by CMRs in required duties (p less than 0.05) and rated as more important the responsibilities of faculty-house staff liaison, house staff leader, house staff role model and teaching house staff (p less than 0.05) and the attributes of clinical judgement, medical knowledge, clinician model and research interests (p less than 0.03). All of the PCs and 97% of the CMRs rated the position as somewhat to very necessary; 83% of the PCs and 66% of the CMRs would not alter the present CMR roles. A total of 92% of the PCs felt that the position was very or somewhat advantageous with respect to a future private practice, compared with 67% of the CMRs (p less than 0.02). Increased administrative and committee duties, decreased teaching and future reductions in house staff were identified as major but reversible threats to the unique quality of the CMR position. We conclude that the CMR has a necessary, important and highly regarded role in Canadian university hospitals that could possibly be improved by regular review by the PC and CMR at each hospital to avoid the identified problems.     

Endothelial function and aqueous humor flow rate in patients with Fuchs' dystrophy

Using a two-dimensional scanning fluorophotometer, we studied 50 subjects with symmetric ocular involvement of Fuchs' dystrophy without epithelial edema. Twenty-six subjects with confluent or nearly confluent cornea gutata with increased corneal thickness and 24 subjects with mild to moderate cornea guttata with normal corneal thickness were compared to normal control subjects. There were no statistically significant differences in endothelial permeability between the three groups. Corneal thickness was significantly increased in the subjects with confluent to nearly confluent guttae, however. These results suggest that endothelial pump function may be affected in subjects with advanced cornea guttata with stromal edema.     

Are Continuity Clinic Patients Less Satisfied When the Resident Is Postcall?

Due to recent public debate and newly imposed resident work hour restrictions, we decided to investigate the relationship of resident call status to their ambulatory patients' satisfaction. Resident continuity clinic patients were asked to rate their level of satisfaction on a 10-point Likert-type scale. Using multiple regression approaches, these data were then assessed as a function of resident call status. We found that in 646 patient encounters, patient satisfaction scores were significantly less when the resident was postcall, 8.99 ± 1.8, than when not postcall, 9.31 ± 1.3. We herein discuss etiologies and implications of these findings for both patient care and medical education.     

新生小猪脑含氧量和O-酪氨酸在双侧颈动脉结扎和失血中的变化

采用小猪双侧颈动脉结扎伴失血模型检测双侧颈动脉的结扎伴失血对脑氧分压和O-酪氨酸变化的影响,结果发现小猪脑氧分压为(51±4)托.颈动脉结扎和失血后60min降为(10±1.5)托(P<0.001),当颈动脉恢复通畅和失血再灌注后,脑氧分压增至(40±6)托,此值与预试验时的脑氧分压无明显差异.对照组中脑纹状体中的O-酪氨酸的含量为(0.57±0.19)nmoles/g组织.缺血试验后1h其含量明显升为(29±0.5)nmoles/g组织(P<0.005),显示缺血后再灌注导致脑纹状体O-酪氨酸显著上升.提示组织中羟基产生增加,可能与新生小猪脑缺血和再灌注损伤有一定作用.     

Effect of indomethacin on arachidonic acid metabolism in human leukocytes stimulated ex vivo.

We had previously shown that inhibition of cyclooxygenase in vitro by indomethacin can cause increased formation of products of the 5-lipoxygenase pathway of arachidonic acid metabolism in leukocytes. To determine if this effect also occurred in vivo, we studied leukocyte arachidonic acid metabolism in 12 volunteers before and after ingestion of 150 mg indomethacin daily for 3 days. Blood was collected before treatment and 2 hours, 2 days, and 5 days after the final dose of indomethacin. Serum thromboxane B2, a measure of platelet cyclooxygenase activity, was profoundly suppressed 2 hours after the final dose of indomethacin but had recovered to control values at 2 days. Mixed leukocyte suspensions and purified neutrophil suspensions were prepared and stimulated with calcium ionophore A23187 and the resultant 5-lipoxygenase metabolites were quantified by HPLC. Two hours after the final dose of indomethacin, the stimulated levels of 5-hydroxyeicosatetraenoic acid, leukotriene B4, and leukotriene C4 were significantly increased to 247% +/- 68%, 135% +/- 14%, and 149% +/- 23% of pretreatment values, respectively. Two days after the final dose of indomethacin, 5-hydroxyeicosatetraenoic acid levels were still significantly elevated. By 5 days all parameters had returned to baseline. Similar effects were not observed in purified neutrophil suspensions, probably because of the loss of indomethacin from the cells during the multiple washing procedures used in their preparation. This is in accord with the reversible nature of the inhibitory effect of indomethacin on cyclooxygenase. We conclude that indomethacin at a commonly used dose increases the ability of circulating leukocytes to produce 5-lipoxygenase products.