A simple method of assessing the temporomandibular joint with helical computer tomography: technical note.
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Artifacts↗
Biomedical subjects
D K Li
Publications and source records attributed to D K Li.
Maternal history of subfertility and the risk of congenital urinary tract anomalies in offspring.
I studied the relation between a maternal history of subfertility and the risk of congenital urinary tract anomalies (CUTAs) in a case-control study. I defined subfertility as having unprotected intercourse for more than 12 months without getting pregnant at any time before the conception of the index pregnancy. A maternal history of subfertility was associated with a slightly increased risk of CUTAs (adjusted odds ratio (OR) = 1.4, 95% confidence interval (CI) 0.8-2.4). Risk was higher for mothers whose subfertility occurred at 20 years of age or younger (OR = 2.2, 95% CI 1.0-4.9). The effect of a maternal history of subfertility on the risk of CUTAs was exacerbated by maternal smoking during the index pregnancy and by an early onset of smoking history.
Case-Control Studies↗
Reply to "Prenatal exposure to sex hormones: a case-control study".
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Abnormalities, Drug-Induced↗
A comparison between magnetization transfer ratios and myelin water percentages in normals and multiple sclerosis patients.
Magnetization transfer and T2 relaxation data were obtained for five white and six gray matter brain structures from 10 normal volunteers and 9 multiple sclerosis patients. Thirty MS lesions were also analyzed. Magnetization transfer ratios and myelin water percentages were compared. Both techniques showed a significant difference between the average of white and gray matter of the normal volunteers as well as the average of normal-appearing white matter and gray matter of the multiple sclerosis patients. The average magnetization transfer ratio and myelin water percentage for lesions were significantly lower than those of normal-appearing white matter. Myelin water percentages and magnetization transfer ratios were uncorrelated in white and gray matter but showed a small (R = 0.5, P = 0.005) but significant correlation in multiple sclerosis lesions. In summary, the myelin water percentage and the magnetization transfer ratio provide quantifiable but largely independent measures of multiple sclerosis lesion pathology.
Adult↗
Unexpected vaginal bleeding and associated gynecologic care in postmenopausal women using hormone replacement therapy: comparison of cyclic versus continuous combined schedules.
OBJECTIVE: To measure gynecologic resources required to care for women who have unexpected vaginal bleeding while using hormone replacement therapy (HRT). DESIGN: A retrospective cohort study based on review of medical records. SETTING: A large health maintenance organization. PATIENT(S): We studied 284 women using continuous combined HRT and 306 women receiving cyclic HRT. MAIN OUTCOME MEASURE(S): We noted episodes of unexpected vaginal bleeding and associated clinic visits and gynecologic procedures recorded during a mean follow-up period of 2 years. RESULT(S): Among women using cyclic HRT for the first time, 38.3% had > or = 1 visit for unexpected bleeding and 12.3% had > or = 1 endometrial biopsy. Among women starting continuous combined HRT, 41.6% had > or = 1 visit for unexpected bleeding and 20.1% had > or = 1 endometrial biopsy. After adjusting for potential confounding variables, we found that recipients of cyclic and continuous combined HRT had similar risks of unexpected bleeding and endometrial biopsy. However, among women continuing HRT for >2 years, those using the continuous combined regimen had somewhat lower rates of unexpected bleeding (22.3 events per 100 patient-years) and endometrial biopsy (10.3 events per 100 patient-years) than those using the cyclic regimen (37.8 episodes of unexpected bleeding per 100 patient-years and 13.9 endometrial biopsies per 100 patient-years). CONCLUSION(S): Unexpected vaginal bleeding and the gynecologic resources required to manage it decreased after 2 years in women using continuous combined HRT but did not decline among those using cyclic HRT.
Aged↗
Transient neurologic symptoms after spinal anesthesia: an epidemiologic study of 1,863 patients.
BACKGROUND: Recent evidence suggests that transient neurologic symptoms commonly follow lidocaine spinal anesthesia. However, information concerning factors that affect their occurrence is limited. Accordingly, to evaluate many potential risk factors, the authors undertook a prospective, multicenter, epidemiologic study. METHODS: On a voluntary basis, anesthetists at 15 participating centers forwarded a data sheet on patients who had spinal anesthesia to a research nurse blinded to the details of anesthesia and surgery. A subset was randomly selected for follow-up. The pressure [corrected] of transient neurologic symptoms, defined as leg or buttock pain, was the principal outcome variable. Logistic regression was used to control for potential confounders, and adjusted odds ratios and confidence intervals were used to estimate relative risk. RESULTS: During a 14-month period, 1,863 patients were studied, of whom 47% received lidocaine, 40% bupivacaine, and 13% tetracaine. Patients given lidocaine were at higher risk for symptoms compared with those receiving bupivacaine (relative risk, 5.1; 95% CI, 2.5 to 10.2) or tetracaine (relative risk, 3.2; 95% CI, 1.04 to 9.84). For patients who received lidocaine, the relative risk of transient neurologic symptoms was 2.6 (95% CI, 1.5 to 4.5) with the lithotomy position compared with other positions, 3.6 (95% CI, 1.9 to 6.8), for outpatients compared with inpatients, and 1.6 (95% CI, 1 to 2.5) for obese (body mass index >30) compared with nonobese patients. CONCLUSIONS: These results indicate that transient neurologic symptoms commonly follow lidocaine spinal anesthesia but are relatively uncommon with bupivacaine or tetracaine. The data identify lithotomy position and outpatient status as important risk factors in patients who receive lidocaine. Among other factors postulated to increase risk, obesity had an effect of borderline statistical significance, whereas age, sex, history of back pain, needle type, and lidocaine dose and concentration failed to affect risk.
Adult↗
Penetration kinetics of 5-fluorouracil into pancreatic fluid in post-pancreatoduodenectomy patients.
Our aim was to investigate the pharmacokinetic behavior of 5-fluorouracil (5-FU) in pancreatic fluid and to evaluate its penetration characteristics in post-pancreatoduodenectomy patients. After completing the external drainage of the pancreatic duct during pancreatoduodenectomy surgery, eight patients were administered 1.0 g 5-FU i.v. by a 5 min infusion after the eighth day post-surgery on average. Blood and pancreatic fluid were collected, and the 5-FU concentrations were determined by HPLC assay. Their pharmacokinetic parameters were obtained by PCNONLIN and statistical analysis was performed. The Cmax was 20.03 +/- 18.25 mg/l in pancreatic fluid with a Tmax of 15.6 +/- 9.5 min following i.v. administration and 49.69 +/- 20.75 mg/l in plasma. 5-FU in plasma and pancreatic fluid were all in conformity with a non-linear model with a K(m) of 1098.08 +/- 1426.57 and 11.08 +/- 6.38 mg/l, respectively. The concentrations in pancreatic fluid were similar to that observed in plasma with an average penetration index up to 1.01 +/- 0.49. It is suggested therefore that 5-FU is capable of penetrating from blood into the pancreas as evidenced by the observed pancreatic concentrations.
Body Fluids↗
Pharmacokinetics of 5-fluorouracil and its penetration into pancreatic juice in dogs.
AIM: To study the pharmacokinetic behavior of 5-fluorouracil (5-FU) in pancreatic juice in dogs and its correlation with 5-FU in plasma, and to evaluate its penetration characteristics. METHODS: After placing a pancreatico-drainage tube, 8 dogs were injected 5-FU 250 mg i.v. Blood and pancreatic samples were collected and the 5-FU concentrations were determined by HPLC. The pharmacokinetic parameters were obtained with statistical analysis. RESULTS: The mean slopes of the terminal phase (K10) in plasma and pancreatic juice were 9.4 h-1 and 10.2 h-1, respectively (P > 0.05). The pharmacokinetic behaviors of 5-FU in plasma and pancreatic juice fitted a nonlinear model. Its penetration index was 3.39 +/- 2.84. The penetration of 5-FU from blood to pancreatic juice was relatively rapid, demonstrating a consistently higher concentration in pancreatic juice than in plasma. CONCLUSIONS: The elimination phase of 5-FU in plasma was similar to that in pancreatic juice, indicating that they were in the same kinetic compartment.
Animals↗
In vivo measurement of T2 distributions and water contents in normal human brain.
Using a 32-echo imaging pulse sequence, T2 relaxation decay curves were acquired from five white- and six gray-matter brain structures outlined in 12 normal volunteers. The water contents of white and gray matter were 0.71 (0.01) and 0.83 (0.03) g/ml, respectively. All white-matter structures had significantly higher myelin water percentages (signal percentage with T2 between 10 and 50 ms) than all gray-matter structures. The range in geometric mean T2 of the main peak for both white and gray matter was from 70 to 86 ms. T2 distributions from the posterior internal capsules and splenium of the corpus callosum were significantly wider (width is related to water environment inhomogeneity) than those from any other white- or gray-matter structures. Thus, quantitative measurement and analysis of T2 relaxation reveals differences in brain tissue water environments not discernible on conventional MR images. These differences may make short T2 components reliable markers for normal myelin.
Adult↗
Clinical and magnetic resonance imaging changes correlate in a clinical trial monitoring cyclosporine therapy for multiple sclerosis. The MS Study Group.
Magnetic resonance imaging (MRI) was used to monitor cyclosporine therapy for chronic progressive multiple sclerosis in a multicenter clinical trial and an analysis was performed to determine whether there was a correlation between clinical changes and MRI changes. MRI was performed on 163 patients at the onset and completion of the 2-year study. Burden of disease (BOD, lesion load) was quantitated by a single observer using a computer program. Active lesions were also identified. The Expanded Disability Status Scale (EDSS) score was determined every 3 months MRI data did not show any effect of cyclosporine treatment on BOD progression (mean 24.5% increase/yr) or lesion activity. However, there was a statistically significant positive correlation between the baseline total BOD value and the baseline EDSS score (r = 0.221, p = 0.005) and a positive correlation between the percent changes in BOD from baseline to exit and EDSS score (r = 0.186, p = 0.018). The study supports the concepts that MRI is a useful technique in monitoring therapeutic trials and that MRI is a direct measure of pathology.
Brain↗
Premenopausal ovariectomy-related bone loss: a randomized, double-blind, one-year trial of conjugated estrogen or medroxyprogesterone acetate.
The purpose of this study was to contrast the effects of conventional estrogen treatment with medroxyprogesterone on cancellous and cortical bone change in the first year following premenopausal ovariectomy. This 1-year double-blind randomized therapy trial was stratified by osteoporosis family history and performed in an academic medical center and community hospitals. Premenopausal women 45 +/- 5 years old, postovariectomy for benign diseases were provided 600 mg/day of calcium and randomized to daily therapy with conjugated equine estrogen (CEE, 0.6 mg) or medroxyprogesterone (MPA, 10 mg). The primary outcome variable was spinal quantitative computed tomography (QCT) bone density change over 1 year with additional outcomes of dual-energy X-ray absorptiometry (DXA) of proximal femur (FN), whole body (WB), and spine segment (WBS) and N-telopeptide, bone-specific alkaline phosphatase, and other bone marker, hormonal, and weight changes. Results in the 33 women completing the study, whose initial bone densities were normal (QCT 133 mg/cm3, femoral neck 0.94 g/cm2, whole body DXA 1.13 g/cm2), showed annual QCT loss during CEE therapy of -11.5 mg/cm3 (p < 0.0007) and MPA bone loss of -19.7 mg/cm3 (p < 0.0001). Losses were marginally greater on MPA than CEE (p = 0.04). Extremely high postovariectomy (5 days) and pretreatment resorption markers (> 3 SD above premenopausal normal levels) were significantly related to bone loss. Across the year, resorption decreased during CEE but increased on MPA treatment. Significant DXA bone losses were prevented by CEE treatment (-1.4% FN, -.4% WB, and -1.5% WBS, all NS). However, DXA bone loss was not prevented by MPA treatment (-5% FN, -2.8% WB, and -6.1% WBS, all p < 0.03). Average weight gain was significant (+ 3.2 +/- 4.0 kg) and greater on CEE than MPA (+ 4.7 vs. + 2.0 kg, p = 0.049). In conclusion, CEE therapy did not prevent significant 8% cancellous spinal bone loss in the first year following premenopausal ovariectomy, despite supplementation with 600 mg/day of calcium, good control of vasomotor symptoms, and nearly 5 kg of gain in weight. Significant DXA bone loss, however, was prevented by CEE, but not by MPA therapy. These unexpected results were statistically related to high bone resorption following ovariectomy, which CEE suppressed but MPA did not. Bone formation markers increased during MPA therapy but were unchanged during CEE therapy.
Absorptiometry, Photon↗
Importance of magnetic resonance imaging and gadolinium enhancement.
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Gadolinium↗
Ovulatory premenopausal women lose cancellous spinal bone: a five year prospective study.
Healthy premenopausal women with regular cycles are believed to be increasing or maintaining bone density. However, few studies have prospectively documented spinal cancellous bone, the bone that changes rapidly in response to reproductive hormones, in this population. Furthermore, our previous one-year study documented that 24% of the one-year bone change by quantitative computed tomography (QCT) was related to subclinical ovulatory disturbances (short luteal phase and non-ovulation) in the presence of regular menstrual cycles. The purpose of this study was to document the cancellous bone change over five years in this initially ovulatory, premenopausal cohort of 66 healthy women. Thirty-seven women, who continued to be premenopausal and have regular cycles, completed this five-year study. Those enrolled differed only by being older and weighing less than those who could not be contacted (n = 19) or who declined to participate (n = 10). Documentation of current ovulatory characteristics was obtained for at least three cycles in 27 women. At the five-year assessment, the volunteers were 40.6 (range 26-47) years old, weighed 58.5 (41-77) kg, and were 160.9 (149-174) cm in height. All were premenopausal, healthy, nonsmokers with regular menstrual cycles (mean 27.7, range 24-33 days). Six women with intervening events (such as pregnancy or use of oral contraceptives) had interval (12 to 60 months) QCT changes similar to the remaining 31 (-7.98 vs. -4.92 mg/cm, p = 0.1, respectively). Mean five-year QCT was 143.0 +/- 20.2 mg/cm, whereas the initial mean value was 151.9 +/- 20.1 mg/cm. Significant QCT loss over five years (-8.9 +/- 6.2 mg/cm) (95% Cl -6.9 to -11.0) correlated with QCT change in the first year (r = 0.629, p < 0.001). First-year change was not related to the subsequent four-year interval change (r = -0.056, p = 0.74), however. Five-year QCT change was not related to age, weight, osteoporosis family history, estimated calcium intake, or exercise, but did correlate with year one luteal index (luteal/cycle length) (r = 0.339, p = 0.043). Significant cancellous spinal bone loss occurs in healthy, ovulatory premenopausal women, and is influenced by subclinical disturbances of ovulation.
Adult↗
Thymus in myasthenia gravis: comparison of CT and pathologic findings and clinical outcome after thymectomy.
PURPOSE: To correlate computed tomographic (CT) appearance of the thymus with results from histologic examination of thymic tissue and clinical outcome in patients with generalized myasthenia gravis who underwent thymectomy. MATERIALS AND METHODS: Forty-five patients with myasthenia gravis underwent CT of the thorax and thymectomy. Findings at clinical follow-up were available in all patients. RESULTS: Twenty-six patients had normal CT findings, seven had a diffusely enlarged thymus, and 12 had a focal mass. The results of histologic examination showed that 16 of 26 patients with normal CT findings had normal thymic tissue and 10 had lymphoid follicular hyperplasia; all seven patients with an enlarged thymus had lymphoid hyperplasia. Five of 12 patients with a focal mass at CT had lymphoid hyperplasia, and seven had thymoma. Clinical improvement following thymectomy was observed in 27 (93%) of 29 patients with lymphoid hyperplasia or thymoma and 11 (69%) of 16 patients with normal histologic examination (P < .03, chi(2) test). CONCLUSION: The presence of an enlarged thymus or a focal mass in patients with myasthenia gravis indicates lymphoid hyperplasia or thymoma. However, CT is of limited value in distinguishing lymphoid follicular hyperplasia from a normal thymus or thymoma and in predicting clinical outcome.
Adolescent↗
Maternal smoking during pregnancy and the risk of congenital urinary tract anomalies.
To study maternal smoking during pregnancy and the risk of congenital urinary tract anomalies, we interviewed mothers of 118 affected infants born to residents of western Washington State during 1990 and 1991 and mothers of 369 control infants randomly selected from those without birth defects delivered during those years in five hospitals in King County, Washington. Maternal smoking was associated with an increased risk of congenital urinary tract anomalies in offspring (adjusted odds ratio [OR] = 2.3; 95% confidence interval [CI] = 1.2, 4.5). This risk was higher among light smokers (1-1000 cigarettes during the pregnancy) (OR = 3.7; 95% CI = 1.7, 8.6) than among heavy smokers (OR = 1.4; 95% CI = 0.6, 3.3). Our results corroborate previous findings and support the hypothesis of a causal relation.
Adult↗
Oral contraceptive use after conception in relation to the risk of congenital urinary tract anomalies.
The authors conducted a case-control study of the relation of OC use after conception to the occurrence of congenital urinary tract anomalies (CUTAs). Singleton CUTA cases with no known chromosomal abnormality from seven counties in western Washington State born during the period January 1, 1990-December 31, 1991 were identified through the Washington State Birth Defect Registry. Controls without birth defects were randomly selected from singleton births that occurred in the same year as the cases in five large hospitals in King County. Mothers of the 118 cases and 369 controls were interviewed to obtain their contraceptive history as well as other information. Mothers of nine cases (7.6%) and eight controls (2.2%) had taken OCs at some time during the pregnancy. After adjustment for birth year and county of maternal residence, OC use after conception was associated with an almost five-fold increased risk of having a baby with a CUTA [odds ratio (OR) = 4.8, 95 percent confidence interval (CI), 1.6-14.1] relative to no contraception at or after conception. Use of other contraceptive methods after conception was not related to the risk of CUTAs. OC use during the 3 or 6 months prior to the conception also was not associated with the risk of CUTAs. Further adjustment for sociodemographic factors, reproductive history, perinatal exposure to exogenous agents, and past OC use did not change the results, nor did restricting the analysis to residents of King County.(ABSTRACT TRUNCATED AT 250 WORDS)
Abnormalities, Drug-Induced↗
Periconceptional multivitamin use in relation to the risk of congenital urinary tract anomalies.
To study the relation of maternal periconceptional vitamin use to the risk of a congenital urinary tract anomaly (CUTA), we conducted a case-control study using the Washington State Birth Defect Registry. We identified CUTA cases with no known chromosomal abnormality in seven counties in western Washington State occurring between January 1, 1990, and December 31, 1991. We randomly selected a sample, as controls, of all infants delivered in five large hospitals in King County who did not have a birth defect and who were born in the same year as the cases. About 55% of all infants in King County and a smaller proportion of infants in the other six counties are delivered in these five hospitals. We interviewed mothers of 118 cases and 369 controls to obtain information about their vitamin use during the pregnancy and during the year before the conception. After adjustment for maternal race, family income, county of maternal residence, and birth year, we found that women who used multivitamins during the first trimester had only 15% the risk of bearing a child with a CUTA compared with women who did not take vitamins [odds ratio (OR) = 0.15; 95% confidence interval (CI) = 0.05-0.43]. The reduction was smaller for use restricted to the second or third trimesters (OR = 0.31; 95% CI = 0.09-1.02). Among women who used vitamins during the first trimester, vitamin use before conception was not associated with any further reduction in the risk, nor did there appear to be an association with the amount or brand of vitamin used.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Electric blanket use during pregnancy in relation to the risk of congenital urinary tract anomalies among women with a history of subfertility.
To study the potential effect of prenatal exposure to electromagnetic fields on the occurrence of cogenital urinary tract anomalies (CUTAs) in offspring, we conducted a case-control study in western Washington State. CUTA cases without known chromosomal abnormalities were identified from the Washington Birth Defects Registry. Controls without birth defects were randomly selected from among infants born in five large hospitals in King County, WA. Mothers of cases and controls were interviewed to obtain information on prenatal use of electric blankets, electrically heated water beds, and video display terminals. After adjustment for potential confounders, the risk of CUTAs was found not to be materially associated with these prenatal exposures among all subjects. Among women with a history of subfertility, however, prenatal use of electric blankets was associated with a more than four-fold increase in the risk of CUTAs [adjusted odds ratio (OR) = 4.4; 95% confidence interval (CI) = 0.9-22.7]. The risk was greater if the exposure occurred during the first trimester (adjusted OR = 10.0; 95% CI = 1.2-85.5). The risk also appeared to increase with increasing duration of electric blanket use. Despite small numbers and the potential for recall bias, our study indicates that identifying a susceptible population may be required for detecting adverse reproductive effects of electromagnetic fields.
Abnormalities, Radiation-Induced↗