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Biomedical subjects

D Li

Publications and source records attributed to D Li.

At least 865 records · Page 48Linked to original sources
PubMed1991

Neuropsychological performance in patients with mild multiple sclerosis.

Although changes in cognitive function in patients with multiple sclerosis (MS) have been reported, these changes have been traditionally associated with the later stages of the disease. In the current study, a comprehensive neuropsychological battery was administered to MS patients (N = 86) in whom the disease progression was relatively mild and in remission and a demographically well-matched control group (N = 46). Besides the expected differences in tests of motor function, the two groups also differed on a number of cognitive tests with no motor demands. The two cognitive functions that appear impaired were learning and memory. Given that similar deficits have been found in MS patients with more severe symptoms, it is argued that changes in cognitive function can occur in the mild stages of the disease.

Adult↗
PubMed1991

The 5'-flanking region of the mouse thymidylate synthase gene is necessary but not sufficient for normal regulation in growth-stimulated cells.

The thymidylate synthase (TS) gene is a housekeeping gene that is expressed at much higher levels in proliferating cells than in quiescent cells. We have studied the role of the TS 5'-flanking sequences in regulating the level of expression of the mouse TS gene. A variety of chimeric TS minigenes that contain different promoters linked either to the TS coding region (with or without introns) or to the chloramphenicol acetyltransferase (CAT) coding region were constructed. The activities of the minigenes were determined by transfecting them into cultured cells and measuring the levels of mRNA or enzyme derived from the chimeric genes. We found that the mouse TS promoter had about the same strength as the simian virus 40 early promoter but was significantly stronger than the herpes simplex virus thymidine kinase promoter. Stable transfection studies revealed that minigenes consisting of the normal TS promoter (extending to -1 kb), coding region, and polyadenylation signal were regulated normally in response to growth stimulation. When the TS promoter was replaced by the simian virus 40 early promoter or by a TS promoter that retained only 60 nucleotides upstream of the first transcriptional start site, the minigene was expressed constitutively. A minigene consisting of the TS promoter (extending to -1 kb) linked to the CAT coding region was also expressed constitutively. These observations indicate that sequences upstream of the transcriptional start sites of the TS gene are necessary, although not sufficient, for normal growth-regulated expression of the mouse TS gene.

Animals↗
PubMed1991

The nigrostriatal dopaminergic pathway in Wilson's disease studied with positron emission tomography.

Movement disorders, including Parkinsonism, are prominent features of neurological Wilson's disease (WD). This suggests there may be dysfunction of the nigrostriatal dopaminergic pathway. To explore this possibility, five patients were studied using positron emission tomography (PET) with 18F-6-fluorodopa (6FD), and magnetic resonance imaging (MRI). We calculated striatal 6FD uptake rate constants by a graphical method and compared the results with those of 18 normal subjects. It was found that four patients with symptoms all had abnormally low 6FD uptake, and the one asymptomatic patient had normal uptake. PET evidence for nigrostriatal dopaminergic dysfunction was present even after many years of penicillamine treatment. It is concluded that the nigrostriatal dopaminergic pathway is involved in neurological WD.

Adult↗
PubMed1991

Three-dimensional upper airway computed tomography in obstructive sleep apnea. A prospective study in patients treated by uvulopalatopharyngoplasty.

The success of uvulopalatopharyngoplasty in treating obstructive sleep apnea varies considerably. Some of this variability may be accounted for by differences in the site of upper airway narrowing. To determine whether preoperative awake upper airway and soft tissue volumes predict the response to uvulopalatopharyngoplasty, preoperative awake computed tomograms (CT) of the upper airway were performed on 60 consecutive patients with symptomatic obstructive sleep apnea. Tracings were made from the CT scans of upper airway, tongue, and soft palate. Computer software was used to determine the cross-sectional area and volume of the upper airway, tongue, and soft palate. Patients underwent overnight polysomnograms before and 3 months after uvulopalatopharyngoplasty. Tongue volume was larger (p less than 0.02) and both upper airway to tongue volume (p less than 0.0005) and oropharynx to soft palate volume ratios (p less than 0.01) were smaller in obese patients. A good response to uvulopalatopharyngoplasty as defined by a postoperative apnea index of less than 5 apneas/h or a reduction in apnea index greater than or equal to 50% was seen in 50 patients (83%). Patients who had a good response had a smaller oropharyngeal cross-sectional area (p less than 0.01), a smaller upper airway volume (p less than 0.05), a smaller upper airway to tongue volume ratio (p less than 0.01), and a smaller oropharynx to soft palate volume ratio (p less than 0.05). Obese patients with obstructive sleep apnea have larger tongues and smaller upper airways relative to tongue and soft palate size. Patients with smaller upper airways, particularly relative to tongue and soft palate size, have a good response to uvulopalatopharyngoplasty.

Computer Graphics↗
PubMed1991

Magnetic resonance imaging of the upper airway in obstructive sleep apnea before and after chronic nasal continuous positive airway pressure therapy.

Magnetic resonance imaging (MRI) provides high-resolution images of the upper airway and is useful for assessing conditions associated with increased tissue water content. To determine whether nasal continuous positive airway pressure (CPAP) changes awake upper airway morphology in obstructive sleep apnea (OSA), we performed awake upper airway MRI scans on five male patients with moderate to severe OSA before and after 4 to 6 wk of nasal CPAP therapy. MRI scans were performed using spin echo pulse sequences to examine detailed anatomy and inversion recovery sequences to assess mucosal water content. Patients did not have nasal CPAP applied during the MRI scans. Axial and sagittal images were obtained, and tracings were made of the upper airway, tongue, and soft palate. Utilizing computer graphics, cross-sectional areas and volumes were calculated for each anatomic structure. A subjective grading system was used to assess upper airway mucosal water content. Pharyngeal volume and minimum pharyngeal cross-sectional area increased (p less than 0.05) and tongue volume decreased (p less than 0.01) following chronic nasal CPAP therapy. The increase in pharyngeal volume occurred mainly in the oropharynx (p less than 0.01). Upper airway mucosal water content decreased in the oropharynx (p less than 0.05). We conclude that chronic nasal CPAP therapy during sleep in patients with OSA produces changes in awake upper airway morphology. These changes may be due to resolution of upper airway edema. The upper airway of patients with OSA can be accurately and repeatedly assessed using MRI.

Adult↗
PubMed1991

Regional metabolism in microsmic patients with schizophrenia.

The cerebral glucose metabolism of eight patients with schizophrenia and an olfactory agnosia was compared with that of eight normosmic patients with schizophrenia and eight normal controls. Since all patients were scanned while on their current medication regimen, the duration and dosage of the medication of the two patient groups were compared. Similarly, duration and dosage were correlated with absolute regional metabolic rates. No significant effects were found in these analyses. The patients with schizophrenia had significantly lower rates of frontal metabolism than the normal controls. However, the patients with schizophrenia and an olfactory agnosia had a lower right basal ganglia and thalamic metabolism than the normosmic patients with schizophrenia.

Adult↗
PubMed1991

Correlation between gene expression and chromatin conformation of c-fos and N-ras in human liver and hepatoma.

In situ hybridization revealed an apparently higher expression of N-ras and c-fos in human hepatoma than in its adjacent liver tissue. When the isolated nuclei were partially digested with micrococcal nuclease followed by DNA extraction, gel electrophoresis and hybridization with labelled probes, it was shown that in hepatoma the c-fos and N-ras DNA sequences were mainly distributed on the nucleosomes of lower order structures, while these gene sequences in the adjacent liver tissue were found mainly on the nucleosomes of higher order structures. These results clearly indicate a close correlation between gene expression and chromatin conformation of c-fos and N-ras.

Carcinoma, Hepatocellular↗
PubMed1991

[Application of polymerase chain reaction in amplification of human cytomegalovirus B gene code region].

A nucleic acid amplification procedure, the polymerase chain reaction (PCR), has been used to amplify the human cytomegalovirus (HCMV) B gene code region, and its glycoprotein 52 kd antigenic domain. The primers used in the PCR assay were based on a conserved region of the HCMV B gene sequence. By using primer 1 (5'-AAAGAATTCATGGAATCCAGGATCTG-3', upstream nucleotides 157 to 2877), primer 2 (5'-AAAGAATTCATGAACGTGAAGGAATCG-3', upstream nucleotides 1846 to 2877), and primer 4(5'-ATAAAGCTTAATCAGACGTTCTCTTCTTC-3', downstream nucleotides 157 to 2877 and 1846 to 2877), the HCMV B gene code region sequence and its glycoprotein 52 kd antigenic domain sequence were amplified from the recombinant plasmid pBH1 DNA containing the HCMV B gene. Amplification cycles consisted of denaturation at 92 degrees C for 1 min, annealing at 55 degrees C for 1 min, and extension at 72 degrees C for 1.5 min. The cycles were carried out 30 times in three different water baths, respectively. After the last extension, 10 microliter of each reaction mixture was removed and subjected to electrophoresis on 1.2% agarose gel. Ten microgram of PCR products were obtained from 0.2 microgram of template DNA after the 30 times cycles, and were enough for being used in the restriction site analysis and the construction of clones.

Base Sequence↗
PubMed1991

[Preparation of rotundine-chitosan gelled granules and their drug-release tests].

The paper described a delivery system prepared from granulation of a chitosan solution containing rotundine in a coagulating bath and examined the effects of the ratios of rotundine: chitosan, crosslinking agents and molecular weight of chitosan on the analgesic release rate. It was shown that the rotundine (56.7%)-chitosan (Mw:5.70 x 10(5) degree of deacetylation: 72.4%) gelled granules in an artificial gastroenteric juice (pH 1.0 and 7.2) have T50 of 40 and 180 min respectively, and the total release time sustained over 540 min.

Alkaloids↗
PubMed1991

[Studies on the serogroup of Yersinia enterocolitica. II. Selection and establishment on serogroup reference strains of Yersinia enterocolitica].

Since 1980, we have collected 1120 strains of Yersinia enterocolitica, from the different parts of China. These strains have been obtained from various sources in man, animals and natural environment accompanied by their clinical or ecological information of Yersinia enterocolitica. The results of our tests have shown that the 747 strains have exhibited the clinical morphological and biochemical characteristics of Yersinia enterocolitica. Through comparing under the same conditions, out of the 747 strains 335 have been selected out with better antigenicity and have been produced antisera from their representative strains. This set of antisera is very satisfactory for its potency and specificity. This set of antisera is ready to supply and have good efficacy and application facilitated for control strains on identifying strains and their epidemiologic observation.

Antigens, Bacterial↗
PubMed1991

[Aluminum and fluorine absorption in a perfusion system of rat small intestine in vivo].

Mixtures of aluminum an fluorine in two different ratios in tris-hydroxy-methyl-aminomethane buffered media of pH 7.0 were perfused respectively through the small intestine of the in vivo rat over a period of 40 min. The contents of aluminum and fluorine in the portal vein blood obtained from different perfusion periods were detected and determined simultaneously. The results showed that fluorine absorption was not significant in the mixtures. An obviously large amount of aluminum was absorbed in the mixture with a higher proportion of aluminum (4660 micrograms/ml Al + 200 micrograms/ml F/L), while in the mixture with a lower dose of aluminum (860 micrograms/ml Al + 200 micrograms F/L), a small quantity of aluminum was absorbed. It is evident that the mechanism by which aluminum inhibits fluorine toxicity is that aluminum decreases the intestinal fluorine absorption by the formation of aluminum fluoride complex.

Aluminum↗
PubMed1991

Induction of antitumor activity and experimental expansion of human lung cancer-infiltrating lymphocytes.

In order to look for effector cells which are more efficient and less toxic than LAK cells induced from PBL for use in adoptive immunotherapy, we studied the antitumor activity and in vitro expansion of tumor infiltrating lymphocytes (TIL) from human lung cancers and compared their cytological properties with those of autologous PBL. The results showed: 1) Large numbers of TIL could be obtained from lung cancer tissue, approximately 1-5 x 10(8)/g tumor tissue, with an average TIL to tumor cell ratio of 2.3:1 (21 samples). 2) Fresh TIL were not cytotoxic against either NK-sensitive or -resistant tumor targets. After culturing for 6 to 8 d in the presence of rIL-2, TIL showed significant cytotoxicity and were able to kill autologous and allogeneic tumor targets and fresh solid tumor targets. 3) When maintained in the presence of rIL-2, TIL were able to continue proliferating and expanding for more than 2 mon, with expansion indices of 4-512. TIL stopped proliferating following the disappearance of autologous tumor cells in the culture. 4) Chronological studies revealed that the cytotoxicity appeared after 4 days in culture and reached a peak on the 14th day, and cultured TIL remained cytotoxic for at least 4 wk.

Adenocarcinoma↗
PubMed1991

[Galactose-1-phosphate uridyl transferase and congenital cataract].

The activity of red blood cells galactose-1-p-uridyl transferase (GPUT) was determined by the spectrophotofluorometric method. The average GPUT activity in 102 control subjects was 13. 34 +/- 2. 03u. There were no differences in the sexes and ages. The average GPUT activity in 108 patients with congenital cataract was 11.58 +/- 4. 03u and was lower than that of the controls (P < 0.01). The GPUT activity in 14 of the 108(12.96%)patients was all-3SD below the mean value of the controls (< 7.24u) and the range was from 4.02u to 7.13u with the mean value of 5. 93u being about 44.45% of the normal. The difference between the two groups was statistically significant (P < 0.001). The results indicated that some of the patients with congenital cataract were due to decrease in the GPUT activity. The patients with decrease GPUT activity were mainly suffering from cataracts and their systemic disease were mild.

Adolescent↗
PubMed1991

[Waardenburg syndrome].

We report a patient with Waardenburg syndrome. He suffers from congenital deafness and presents high broad nasal root, synophrys, iris heterochromia and fundus hypopigment. The dystopia canthus is absence. In his family pedigree analysis, we found that his second cousin has oculocutaneous albinism.

Adolescent↗
PubMed1991

[A study on components and compound prescription of huangqin decoction].

The results obtained from the pharmacological experiments have preliminarily demonstrated that the compound prescription is better than its individual component drug in the range and potency of pharmacological activities. In the prescription Radix Scutellariae plays a principal role in pharmacological effects. Radix Scutellariae and Radix Paeoniae Alba can potentiate each other. Radix Glycyrrhizae and Fructus Jujubae in the compound prescription also exhibit biological activities to some extent. The relieving effect of the prescription for spasm and pain may result from the synergistic interaction between Radix Paeoniae Alba and Radix Glycyrrhiza, and the heat clearing and diarrhea stopping action is due to the biological activity of Radix Scutellariae.

Animals↗