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Biomedical subjects

D K Li

Publications and source records attributed to D K Li.

At least 73 records · Page 4Linked to original sources
PubMed1990

Prior condom use and the risk of tubal pregnancy.

The relationship between prior condom use and tubal pregnancy was assessed in a population-based case-control study at Group Health Cooperative of Puget Sound during 1981-86. We interviewed 227 women with a tubal pregnancy who had no clinical indication of infertility and no history of sterilization and 674 similarly defined controls who were matched to the cases on age and county of residence. A history of condom use for more than one year was associated with a decreased risk of subsequent tubal pregnancy (RR = 0.74, 95% CI = 0.44, 1.26) adjusted for the effects of age, current use of contraceptive methods, educational level, and age at first intercourse. The effect was more pronounced when condoms had been used during five-year periods with more than one partner (RR = 0.38, 95% CI = 0.15, 1.0) than during five-year periods with one partner (RR = 0.89, 95% CI = 0.45, 1.76). Condom use for less than one year was unrelated to risk of ectopic pregnancy. Since the use of condoms offers protection against sexually transmitted diseases, one or more of which are likely to be causally related to tubal pregnancy, the observed negative association plausibly represents a protective influence of long-term condom use on the occurrence of tubal pregnancy.

Adult↗
PubMed1990

Glomus of the choroid plexus: the normal spin-echo appearance on magnetic resonance imaging.

The glomus of the choroid plexus is located within the trigone of the lateral ventricles. The magnetic resonance images of the choroid plexus in 624 patients of all ages were reviewed and graded to determine the variation of the appearance of the glomus of the choroid plexus as seen on T2-weighted spin echo (SE). With the moderately T2-weighted SE sequences the intensity of the choroid plexus signal was equal to, or less than, that from deep cerebral grey matter in 76% of patients and greater than that from deep cerebral grey matter in 23%; in 1% of patients the glomus of the choroid plexus was "cyst-like". In all 100 patients studied with the heavily T2-weighted SE sequence the intensity of the choroid plexus signal was greater than that from the deep cerebral grey matter. The variation in the normal appearance of the glomus of the choroid plexus is consistent with known histologic changes described in the literature. The importance of recognizing the glomus of the choroid plexus and not mistaking it for other normal anatomical structures or diseases is evident.

Adolescent↗
PubMed1989

Serial magnetic resonance scanning in multiple sclerosis: a second prospective study in relapsing patients.

A prospective study of serial magnetic resonance (MR) scans of the brain was carried out every 2 weeks for 4 to 6 months in 9 patients with mild, clinically definite, relapsing/remitting multiple sclerosis (MS). Six of the 9 patients developed a total of 12 asymptomatic new lesions in various parts of the brain. In none of the patients were the changes on MR scan accompanied by relevant new neurological symptoms or signs. New MR lesions had a characteristic temporal profile, reaching a maximum size in approximately 4 weeks before gradually shrinking, usually leaving a small residual abnormality indistinguishable from chronic MS lesions. The frequent occurrence of new asymptomatic lesions indicates that MS may be a more active process even in mildly affected asymptomatic patients than has been previously realized. The results emphasize the potential importance of using MR scanning to measure disease activity in laboratory studies of MS and in the assessment of treatment, particularly in asymptomatic patients in the early stages. We suggest that the expanding and contracting new lesions are the basic or primary lesion in MS, that the characteristic demyelinated plaque is represented by the small residual area that these lesions shrink down to, and that the typical collection of scattered white matter lesions in chronic MS may represent the accumulated residua of dozens or more of these active lesions occurring over many years.

Adult↗
PubMed1989

Benign versus chronic progressive multiple sclerosis: magnetic resonance imaging features.

The extent of disease as detected by magnetic resonance imaging was compared between 32 patients with benign multiple sclerosis (MS) and 32 patients with the chronic progressive form matched for age, sex, and disease duration. Computer-assisted quantitation of magnetic resonance images revealed a higher mean lesion load in chronic progressive multiple sclerosis (CPMS); however, in approximately 20% of benign MS patients the lesion load was higher than that in the CPMS patients. CPMS patients had a higher number of infratentorial lesions, yet similar numbers of supratentorial lesions, when compared with benign MS patients. The degree of confluency of lesions and the clinical expression of infratentorial lesions were typically higher in the CPMS patients. Benign MS was characterized by a lower degree of confluency and a higher number of asymptomatic infratentorial lesions. Thus, magnetic resonance imaging shows characteristic differences in magnetic resonance-detected changes between MS patients with different clinical courses.

Adult↗
PubMed1989

Chronic progressive multiple sclerosis: serial magnetic resonance brain imaging over six months.

Eight patients in the chronic progressive stage of multiple sclerosis were studied prospectively with magnetic resonance imaging of the head and neurological examination every 2 weeks for 6 months. There were no clinical relapses and disability ratings did not change between the start and completion of the study. Despite the clinical inactivity, a total of 86 active events (new, reappearing, or enlarging lesions) were identified by magnetic resonance imaging over the 6 months, with 50 (51%) of 98 follow-up scans showing evidence of one or more active lesions. New and changing lesions were indistinguishable in appearance, distribution, and temporal pattern from those previously seen in patients who had relapsing and remitting multiple sclerosis. However, as noted previously, the patients in the chronic progressive stage had many more confluent lesions than did the group in relapse. These results strongly suggest that the frequently observed clinical evolution of multiple sclerosis into a chronic progressive course is not accompanied by a fundamental change in the disease process. In fact the chronic progressive stage seems associated with more active changes demonstrated by scans than does relapsing and remitting multiple sclerosis. This study also confirms our previous experience that serial magnetic resonance imaging is much more sensitive than clinical examination in detecting disease activity in multiple sclerosis.

Adult↗
PubMed1989

Hepatic hemangioma in the presence of fatty infiltration: an atypical sonographic appearance.

The typical hepatic cavernous hemangioma presents no diagnostic difficulty at sonography. In contrast, an atypical hemangioma may cause great concern and result in costly and time-consuming investigations. The presence of diffuse fatty infiltration may result in an atypical echo-poor appearance of the hemangioma. Under such circumstances, computed tomography (CT) may not allow definitive diagnosis and magnetic resonance imaging (MRI) may be necessary.

Fatty Liver↗
PubMed1989

Evidence that Chlamydia pneumoniae, strain TWAR, is not sexually transmitted.

Serum specimens from 230 sexually active women were tested for antibodies to Chlamydia trachomatis and Chlamydia pneumoniae. The women were randomly selected as controls in a population-based case-control study for ectopic pregnancy. A total of 123 had antibody to C. pneumoniae and 39 had antibody to C. trachomatis. There was an association between prevalence of antibody to C. trachomatis and an increasing number of lifetime sexual partners, early age at first intercourse, and a history of gonorrheal infection. The prevalence of antibody to C. pneumoniae was not related to any of these factors. These results provide evidence that the two human species of Chlamydia have a different mode of transmission and that C. pneumoniae is not sexually transmitted.

Adult↗
PubMed1989

The lesion of multiple sclerosis: imaging of acute and chronic stages.

Increased blood-brain barrier (BBB) permeability, important in the pathogenesis of MS, may be demonstrated as lesion enhancement with high-volume delayed CT (HVDCT). We studied 40 MS patients with history, neurologic examination, HVDCT, and MRI. In addition, 7 of the patients with enhancing CT lesions were followed with serial MRI for up to 3 years and 7 months. In 3 of these patients we repeated the HVDCT. Patients with enhancing lesions on CT were younger, had shorter duration of disease, and had more frequent clinical relapses than did patients without enhancement. More than half (56%) of the enhancing CT lesions were in the deep white matter, 23% were periventricular, and 21% were at the gray/white matter junction. Half the CT enhancing lesions, when followed by serial MRI, showed significant changes in lesion size. Although the majority (59%) of these lesions faded, some remained actively changing (25%) or became confluent with adjacent lesions (16%). In 48% of the MRI examinations that showed activity, some lesions were increasing in size while others were simultaneously decreasing in size. This study confirms that MS is a dynamic process in which recurrent episodes of BBB disruption and inflammation play a major role. Recurrent episodes of inflammation may well be a prelude to the largely irreversible changes of demyelination and gliosis.

Acute Disease↗
PubMed1989

Hemangioma of the liver: characteristics exhibited on a 0.15 Tesla scanner.

Twenty-two liver hemangiomas, initially diagnosed using ultrasonography, were imaged with a Picker 0.15 Tesla super-conducting scanner in order to (1) determine the reliability of spin-echo (SE) signal intensity measurements and the calculated T1 and T2 values of both normal tissue and hemangiomas and (2) assess the characteristics of hemangiomas as visualized by a low-field magnetic resonance imaging unit. Reproducible measurements of T1 values and signal intensities are possible (r = 0.93-0.99) but T2 values are less reproducible (r = 0.79) and more variable. T1 values provide the best discrimination between hemangiomas and normal liver (99% successful classification) followed by the SE signal intensity differences (94%). Signal intensity ratios and contrast-to-noise ratios of lesions compared with liver are similar to those of other studies. Most small hemangiomas exhibit homogeneous signal intensity but larger lesions can be nonhomogeneous.

Adult↗
PubMed1988

Multiple sclerosis: a serial study using MRI in relapsing patients.

Prospective monthly magnetic resonance imaging (MRI) studies were done over 6 months in seven relapsing MS patients. MRI and neurologic evaluations were compared for sensitivity in detecting disease activity. Four patients were clinically stable throughout the study. Three patients had five clinical relapses, two localized to the spinal cord and three to the brainstem. Eighteen new and ten enlarging MRI lesions were seen in five patients. Most lesions were less than 10 mm in diameter. All were clinically silent. Two patients developed major enlarging MRI lesions (seen in three slices) which increased in size over 2 months and then gradually became smaller over 2 months, leaving behind small residual areas of abnormality. There were 36 follow-up scans, 17 of which (47%) showed evidence for increasing activity. Thirteen (36%) of the scans had new lesions, most of them being small. This study shows that MRI evidence for disease activity in MS is much more frequent than is clinical evidence.

Adult↗
PubMed1988

Multiple sclerosis: in relapsing patients, immune functions vary with disease activity as assessed by MRI.

We have serially studied immunoglobulin G secretion in vitro, natural killer cell function, and concanavalin A-induced suppression in a group of seven patients with relapsing-remitting multiple sclerosis. In two patients, the development of a large clinically asymptomatic MRI lesion was accompanied by reductions in natural killer cell function, immunoglobulin G secretion in vitro (after pokeweed mitogen stimulation), and concanavalin A-induced suppression without parallel change in lymphocyte markers. We did not see this type of change in matched controls nor in stable multiple sclerosis studied serially. When clinical attacks appeared, there was no significant change in immune function. We conclude that changes in immune function correlate well with the activity of the disease as recognized by MRI. We suspect that decreased natural killer cell function, immunoglobulin G secretion in vitro, and concanavalin A-induced suppression are secondary to the large lesions recognized by MRI.

Adult↗
PubMed1987

Temporal lobe involvement in multiple sclerosis patients with psychiatric disorders.

Patients with multiple sclerosis (MS) frequently develop psychiatric disturbances. The clinical histories and magnetic resonance imaging results from eight patients with MS and psychiatric disorders were compared with those from eight control MS patients matched for age, sex, duration and severity of illness, and clinical course. Both groups had widespread lesions on the magnetic resonance imaging scans; however, the psychiatric group had more clinically defined sites of MS involvement, possibly indicating a difference in the biologic activity of the lesions in this group. The total lesion area was not different between the groups. However, the distribution of lesions did differ; the psychiatric group had significantly more temporal lobe involvement than the control group. These results indicate a role for the cerebral lesions themselves, particularly those in the temporal lobes, in the genesis of psychiatric disorders in MS.

Adult↗
PubMed1987

Magnetic resonance imaging of osteoarthritis: correlation with gross pathology using an experimental model.

Conventional radiography has several limitations in the study of osteoarthritis (OA): changes occur late, they are restricted to bone, and they do not correlate well with the patient's symptoms. Magnetic resonance imaging (MRI) can visualize with great detail the soft tissue changes in and around joints. We have obtained MR images of knees using an experimental model of OA in order to study the early changes of OA, to correlate the images with the gross pathology, and to compare MR images with radiographs. The changes on MRI correlated with the gross pathological changes as assessed by Kendall's rank correlation test as follows: meniscal changes, tau = 0.58 (p less than 0.01); osteophytes, tau = 0.59 (p less than 0.05); capsular fibrosis, tau = 0.55 (p less than 0.05); and overall, tau = 0.68 (p less than 0.001). Abnormalities were evident on MRI as early as 4 weeks after the onset of the disease, which is 8 weeks before they appear on radiographs. Thus, MRI can show changes in OA earlier than radiography can, and the images correlate with the gross pathology.

Animals↗
PubMed1987

Assessment of multiple sclerosis lesions by magnetic resonance imaging.

Fifty patients clinically suspected to have multiple sclerosis (MS), who were classified by Schumacher's criteria into three clinical categories (definite, probable, or possible MS), underwent complete brain magnetic resonance (MR) scans. The T2-weighted spin echo (SE) pulse sequence was more sensitive than inversion recovery (IR) in detecting MS lesions. Greater than 50% of the lesions demonstrated by SE were missed on the corresponding IR slices. However, lesions in the brainstem were more readily assessed using IR. MS lesions appeared larger on SE than on IR. Fifty-five percent of SE-demonstrated lesions were 1 to 2 cm or larger in size, while only 32% of IR-demonstrated lesions were greater than 1 cm. Axial and coronal planes of study demonstrated the same number, size, and location of lesions.

Adult↗
PubMed1986

Positron emission tomography in patients with clinically diagnosed Alzheimer's disease.

Fourteen patients who had clinically diagnosed Alzheimer's disease with mild to severe dementia (mean age 69.1 years) were evaluated by calculation of local cerebral metabolic rate for glucose (LCMR-gl) based on uptake of 18F-2-fluoro-2-deoxyglucose (FDG) detected with positron emission tomography (PET). PET scanning showed that the patients had significantly lower LCMR-gl values than 11 age-matched neurologically normal volunteers (mean age 66.3 years). The differences were most marked in the temporal cortex, followed by the frontal, parietal and occipital cortex. In each case the LCMR-gl value was below the lowest control value in at least one cortical area and usually in several; the reduction in LCMR-gl and the number of regions involved in the patients increased with the severity of the dementia. Deficits noted in neuropsychologic testing generally correlated with those predicted from loss of regional cortical metabolism. The patients with Alzheimer's disease were also examined with magnetic resonance imaging, computed tomography or both; the degree of atrophy found showed only a poor correlation with the neuropsychologic deficit. Significant atrophy was also noted in some of the controls. A detailed analysis of LCMR-gl values in selected cerebral regions of various sizes refuted the hypothesis that the reduction in cortical glucose metabolism in Alzheimer's disease is due to the filling by metabolically inert cerebrospinal fluid of space created by tissue atrophy.

Aged↗
PubMed1986

An epidemiological study on the effect of N, N'-methylene-bis-(2-amino-1,3,4-thiadiazole) (MATDA) on outcomes of pregnancy.

A retrospective cohort study on the effect of the suspected teratogenic pesticide N, N'-methylene-bis-(2-amino-1,3,4-thiadiazole) (MATDA) on outcomes of pregnancy was conducted. The exposed group (6,173 pregnancies) was composed of childbearing women who, during their gestation, consumed rice harvested from a field where MATDA had been applied. The control I group (10,145) came from an adjacent county where MATDA had never been used; the control II group (3,326) consisted of women who had been pregnant previous to the introduction of this pesticide in the same region as the exposed group. The validity of the survey was verified by comparability and data-checking studies. After adjustment for the calendar year, maternal age, and pregnancy order, no significant differences were found in rates of spontaneous abortion, fetal death and stillbirth, birth defects, as well as in sex ratio and birth weight between the study groups. The same result was found in the comparison of individual categories of malformation. The rates of the birth defects were 23.84, 21.49, and 22.78 per 1,000 live births for the exposed, internal, and external control groups, respectively. No dose-response relationship was revealed. The results were consistent with previous reports and indicated the difference between animal experiments and human exposures. Although MATDA is teratogenic in animals, it is clear that the pesticide does not adversely effect outcomes of pregnancy in humans as currently applied.

Abortion, Spontaneous↗
PubMed1986

Comparison of PET, MRI, and CT with pathology in a proven case of Alzheimer's disease.

Positron emission tomography (PET) with fluorodeoxyglucose (FDG), magnetic resonance imaging (MRI), and CT were carried out in a patient with Alzheimer's disease 16 months before he died. At autopsy, the gross appearance of the brain correlated with MRI and CT, which showed some regional atrophy. These were much less revealing than PET, which correlated with microscopic findings of neuronal loss and proliferation of glia. In areas of moderately impaired local cerebral metabolic rate of glucose, as revealed by reduced FDG uptake, there was some gliosis, primarily around the numerous senile plaques. In areas of severe metabolic impairment, there was a profound loss of neurons, extensive gliosis, and a diminished appearance of plaques. PET-FDG is a better measure of the severity of Alzheimer's disease than MRI or CT, because it reflects the degree of neuronal pathology.

Aged↗