Biomedical subjects

J S Luo

Publications and source records attributed to J S Luo.

14 recordsLinked to original sources

PubMed2001

[Formation of the allogeneic tissue engineered cartilage using injectable biomaterial].

OBJECTIVE: To study the feasibility of the formation of allogeneic tissue-engineered cartilage of certain shape in immunocompetent animal using the injectable biomaterial. METHODS: Fresh newborn rabbits' articular cartilages were obtained under sterile condition (< 6 hours after death) and incubated in the sterile 0.3% type II collagenase solution. After digestion of 8 to 12 hours, the solution was filtered through a 150 micron nylon mesh and centrifuged, then the chondrocytes were washed twice with phosphate buffered saline (PBS) and mixed with the biomaterial to create a final cell density of 5 x 10(7)/ml. The cell-biomaterial admixture was injected into rabbits subcutaneously 0.3 ml each point while we drew the needle back in order to form the neocartilage in the shape of cudgel, and the control groups were injected with only the biomaterial or the suspension of chondrocytes with the density of 5 x 10(7)/ml. After 4, 6, 8 and 12 weeks, the neocartilages were harvested to analyze. RESULTS: The new nodes could be touched subcutaneously after 2 weeks. In the sections of the samples harvested after 4 weeks, it was found that the matrix secreted and the collagen formed. After 6 weeks and later than that, the neocartilages were mature and the biomaterial was almost completely degraded. The cudgel-shaped samples of neocartilage could be formed by injection. In the experiment group, there was no obvious immune rejection response. On the contrary, there were no neocartilage formed in the control group. CONCLUSION: The injectable biomaterial is a relatively ideal biomaterial for tissue engineering, and it is feasible to form allogeneic tissue engineered cartilage of certain shape by injection in an immunocompetent animal.

Animals↗

PubMed1998

Biliary glycoprotein (CD66a), a cell adhesion molecule of the immunoglobulin superfamily, on human lymphocytes: structure, expression and involvement in T cell activation.

The biliary glycoproteins (BGP or CD66a), a group of different splice variants of a single gene, are members of the carcinoembryonic antigen family and the immunoglobulin superfamily. Recently, we detected CD66a on IL-2 activated lymphocytes. In this study we characterized the structure and the expression pattern of BGP on human lymphocytes and investigated its role in T cell activation. Lymphocytes express 2 of the 13 known splice variants, i.e. BGPa and BGPb, which are glycosylated in a lymphocyte-specific manner. Both BGPa and BGPb have the long cytoplasmic tail, which contains two immunoreceptor tyrosine-based inhibitory motif (ITIM)-like motifs, but differ in their extracellular region containing 4 and 3 immunoglobulin-like domains, respectively. On PBL BGP is expressed in small amounts only on B cells and Th cells. Stimulation with IL-2 leads to a strong up-regulation of BGP by these cells, and induces de novo BGP expression on gammabeta T cells, CD8+ and CD56+ cells, but not on CD16+ lymphocytes. This up-regulation of BGP seems to be part of the physiological process of T cell activation, since stimulation with anti-CD3 mAb is sufficient to induce BGP up-regulation. Based on the presence of the two ITIM-like motifs, one may expect that BGP inhibits T cell activation, but surprisingly, engagement of BGP enhances the proliferation of anti-CD3-stimulated T cells.

Antigens, CD↗

PubMed1997

Modulations of the effector function and cytokine production of human lymphocytes by secreted factors derived from colorectal-carcinoma cells.

We investigated the in vitro effects of factors secreted by 3 freshly explanted human colorectal-carcinoma (CRC) cell lines on lymphocyte proliferation, IL-2-receptor expression, LAK-cell generation and cytokine secretion. We found that the supernatants of all 3 CRC cell lines inhibited T-cell proliferation in a dose-dependent manner, due to the secretion of immunosuppressive factors (ISFs). In addition, the supernatants of 2 cell lines were able to inhibit LAK-cell generation and to depress IL-2R, but not HLA-DR expression, on PHA-activated T cells. Furthermore, the secretion of cytokines, i.e., IFN-gamma, IL-1beta, IL-2 and TNF-alpha, by peripheral-blood mononuclear cells (PBMC) was differently modulated by the tumor-cell supernatants, e.g., the production of IFN-gamma was reduced in normal PBMC stimulated with PHA. However, the effects induced by the supernatants were not identical: for example, factors from one CRC cell line (w25) influenced early and late events of T-cell activation and division, while 2 others (w19 and te6) contributed only to the inhibition of early events. Some biochemical properties of the ISFs were characterized. Our results suggest that colon-tumor cells can secrete ISFs, which may lead to the in vivo immunosuppression often observed in patients with these tumors.

Colorectal Neoplasms↗

PubMed1997

Fixed-duration multidrug therapy in multibacillary leprosy.

Six-hundred-fifty-seven active multibacillary (MB) leprosy patients were put on fixed-duration multidrug therapy (FD-MDT) between 1985 and 1992 (190 had had no and 235 had had previous treatment with dapsone) and were followed for 5 years after therapy. Two relapses occurred during year 5 of surveillance and both had received dapsone prior to chemotherapy, giving an overall relapse rate of 0.08/100 person-years (py). Excluding the two relapses, 99.4% of the MB patients converted to smear negativity at year 6 after a regular course of FD-MDT. The relapse rate for 35 MB patients with an initial bacterial index (BI) of > 4 with 5 years of surveillance was 0.24/100 py. Reactions occurred more frequently during the first 6 months of MDT, decreasing gradually thereafter, and reaching 0 in year 4 of surveillance. The deformity rate at intake was 22.7% and only 1.8% of MB patients developed new deformities or an increased grade in deformity during therapy.

Adolescent↗

PubMed1995

Establishment of the sulfated 3,3'-diiodothyronine radioimmunoassay and its application in pregnant women.

Sulfation of iodothyronines is a major alternate pathway of thyroid hormone metabolism during fetal development. Sulfated 3,3'-diiodothyronine (T2S) is a low end metabolite of this pathway. Its clinical implications in the prenatal evaluation of fetal thyroid disorders are now being intensively investigated. A highly sensitive and reproducible radioimmunoassay (RIA) for T2S has been established in our laboratory. The detection threshold of the RIA approximated 5 pg T2S. The dose-response curve of T2S was essentially linear between 5-200 pg. An essentially parallel correlation of the dose-response curves for inhibition of binding of radiolabeled T2S and T2S antiserum was found between serial dilutions of serum extracts and the standards. The average intra- and inter-assay coefficients of variation were 7% and 15%, respectively. By applying the T2S RIA, we found that serum titers of T2S in pregnant women increased proportionately to the gestational age (first trimester vs. second trimester vs. third trimester: 30.1 +/- 1.4 vs. 41.6 +/- 1.9 vs. 98.0 +/- 3.9 ng/dL; p < 0.001 each). A high concentration of T2S was detected in cord and maternal serum at birth as compared to the results for non-pregnant women (165.1 +/- 10.3 vs. 113.7 +/- 5.6 vs. 7.5 +/- 0.9 ng/dL). The T2S levels decreased remarkably in maternal circulation 10 days after partuition. Four pregnant women who had two blood samplings four or more weeks apart during the third trimester showed invariable increases of serum T2S titers at later sampling times. Additionally, in the case of a pregnant woman who received two doses of T4 injections (200 micrograms/wk) intraamniotically for a previous Cretin birth, the maternal serum levels of T2S increased promptly from 47 ng/dL [corrected] to 96 ng/dL. Our findings imply that the established T2S RIA is clinically applicable, provide further evidence that the coincident increase of serum T2S titers in pregnant women may reflect ontogenesis of fetal thyroid hormone maturation, and provide a clue to the fetal thyroid status in the prenatal stage. However, more knowledge is still needed regarding the transfer and transformation of sulfated iodothyronine(s) from the fetal compartment to maternal circulation.

Analysis of Variance↗

PubMed1994

Color Doppler flow patterns and flow velocity waveforms of the intraplacental fetal circulation in growth-retarded fetuses.

OBJECTIVE: We examined intraplacental color Doppler flow patterns and spectral Doppler flow velocity waveforms of villous arteries in pregnancies with intrauterine growth retardation. STUDY DESIGN: A total of 192 uncomplicated pregnancies and 29 pregnancies with intrauterine growth retardation between 26 and 41 weeks' gestation were examined in this cross-sectional study. Intraplacental color Doppler flow findings and pulsatility indexes of umbilical and villous arteries were correlated with the presence of intrauterine growth retardation and multiple outcome variables. Villous arteries were identified by their intraplacental color Doppler flow image, and flow velocity waveforms were obtained by superimposition of pulse-wave Doppler. RESULTS: (1) Intraplacental color Doppler flow signals from two or more villous arteries were detected in all 192 normal pregnancies but were undetectable in 8 of 29 fetuses with intrauterine growth retardation (27.6%, p < 0.0001). Absence of intraplacental color Doppler flow signals was associated with fetal distress in 6 of 8 cases (87.5%) and perinatal death in two cases (25.0%), compared with 3 of 21 (14.2%, p < 0.005) and 0 of 21 (not significant) cases of intrauterine growth retardation with detectable intraplacental color Doppler flow. Median Apgar scores at 1 minute were 5 and 8 (p < 0.05), respectively, and at 5 minutes were 8 and 8 (not significant), respectively. (2) Umbilical artery flow velocity waveforms were abnormal (> 95th percentile) in 8 of 21 cases of intrauterine growth retardation (38.0%) with detectable intraplacental color Doppler flow, including two cases with reversed end-diastolic flow. In contrast, the corresponding villous artery flow velocity waveforms were abnormal in only 1 of 21 cases (p < 0.04). CONCLUSION: (1) Failure to detect intraplacental color Doppler flow signals is associated with intrauterine growth retardation and fetal distress. (2) Flow velocity waveforms of detectable villous arteries are usually normal in intrauterine growth retardation, even in the presence of extremely abnormal umbilical artery flow velocity waveforms.

Blood Circulation↗

PubMed1992

Fetal humeral length to detect Down syndrome.

OBJECTIVE: Our aim was to evaluate the utility of ultrasonographic humeral length measurements for detection of fetuses with Down syndrome in the midtrimester of gestation. STUDY DESIGN: Ultrasonographic biometry data obtained before genetic amniocenteses on 43 fetuses with Down syndrome and 204 randomly chosen normal fetuses were analyzed. Regression equations relating biparietal diameter to humeral length and femoral length were used to calculate ratios of observed-to-expected length and sensitivity and specificity at various cutoff points. RESULTS: Humeral length in Down syndrome fetuses was significantly shorter than in normal controls (p less than 0.001). A ratio of 0.90 for observed/expected humeral length yielded a sensitivity of 28%, a specificity of 91%, and positive predictive values of 1.23% and 0.41% in populations at risk for Down syndrome of 1 in 250 and 1 in 750, respectively. The equivalent ratio for femoral length yielded a sensitivity of 19%, a specificity of 91%, and positive predictive values of 0.87% and 0.28% for baseline risks of 1 in 250 and 1 in 750, respectively. CONCLUSIONS: The sensitivity of fetal humeral length measurements for Down syndrome detection in our hands was remarkably lower than previously reported. Independence of this parameter from currently used serum screening markers has not been established; therefore implementation in screening programs is not advisable at this point.

Down Syndrome↗

PubMed1992

Bilateral choroid plexus cysts in trisomy 21.

Whether karyotyping is indicated in a fetus with choroid plexus cysts who is otherwise structurally normal is still controversial. Many authors have suggested basing the decision on cyst size, bilaterality, persistence with advancing gestational age, and association with other anomalies. We report a case of large bilateral choroid plexus cysts in a fetus with trisomy 21 who had no evidence of congenital anomalies or ultrasonographic signs of Down syndrome. Cyst sizes diminished by half over a 3-week period of follow-up. It appears that diminishing size alone should not be considered sufficient reassurance about the normality of the fetal karyotype. A similar case has been previously reported, and it is conceivable that choroid plexus cysts are associated not only with trisomy 18 but also with trisomy 21.

Adult↗

PubMed1992

Monitoring of intravascular fetal transfusions with Doppler velocimetry.

Intravascular fetal transfusions are occasionally complicated by extravascular deposition of transfused blood or by fetal bradycardia on penetration of the needle into the umbilical cord. It is desirable therefore to continuously monitor the intravascular location of the needle and the fetal heart rate. This can be achieved by Doppler velocimetry of the umbilical vein and artery during the procedure. The technique is easily performed, does not require moving of the ultrasonography transducer, and appears to be time efficient.

Blood Transfusion, Intrauterine↗

PubMed1992

Low-risk criteria for cervical-spine radiography in blunt trauma: a prospective study.

STUDY HYPOTHESIS: Cervical-spine radiography does not need to be performed on selected blunt trauma patients who are awake, alert, nonintoxicated, do not complain of midline neck pain, and have no tenderness over the bony cervical spine. STUDY POPULATION: One thousand consecutive patients seen in the UCLA Emergency Medicine Center with a chief complaint of blunt trauma, for whom cervical-spine films were ordered and for whom prospective data questionnaires were completed. METHODS: Clinicians completed data forms for each patient before radiograph results were known. Data items included mechanism of injury, evidence of intoxication, presence of cervical-spine pain and/or tenderness, level of alertness, presence of focal neurologic deficits, and presence of other severely painful injuries unrelated to the cervical spine. Physicians were also asked to estimate likelihood of significant cervical-spine injury. RESULTS: Twenty-seven patients with cervical-spine fracture were among the 974 patients for whom data forms were completed. A number of findings were statistically more common in the group of patients with fracture than without, but no single or paired findings identified all patients with fracture. All 27 patients with fracture had at least one of the following four characteristics: midline neck tenderness, evidence of intoxication, altered level of alertness, or a severely painful injury elsewhere. Three hundred fifty-three of 947 (37.3%) patients without cervical-spine fracture had none of these findings. CONCLUSION: Cervical-spine radiology may not be necessary in patients without spinous tenderness in the neck, intoxication, altered level of alertness, or other severely painful injury. A policy to limit films in such patients would have decreased film ordering by more than one third in this series, while identifying all patients with fracture.

Adolescent↗

PubMed1992

The empiric use of hypertonic dextrose in patients with altered mental status: a reappraisal.

STUDY HYPOTHESIS: Neither response to hypertonic glucose (D50W) nor presence of hypoglycemia can be reliably predicted by "typical" clinical findings (tachycardia, diaphoresis, and/or an available history of diabetes mellitus) in prehospital patients with altered mental status (AMS). POPULATION: Three hundred forty consecutive patients who received D50W for prehospital AMS as ordered by a university hospital paramedic base. METHODS: Review of prehospital records and tape recordings for all subjects to determine presence or absence of tachycardia, diaphoresis, and/or available history of diabetes mellitus at the time of field presentation, as well as response to D50W; final diagnosis was determined from emergency department charts in the 301 patients for whom they were available. RESULTS: Twenty-five patients (7.4%) had a complete response to D50W: 20 had hypoglycemia, diagnosis for one patient was unknown, and four had other causes of AMS. Three patients with an ED diagnosis of hypoglycemia had partial or equivocal responses to D50W, and five had no response. Complete responders were more likely than other patients to have diaphoresis (40% vs 13%, P less than .001) and available history of diabetes (52% vs 12.1%, P less than .001) but not tachycardia (36% vs 35.2%, P = NS). Nine complete responders, including five with hypoglycemia, had none of the three clinical signs. CONCLUSION: Although patients with hypoglycemia who respond to D50W are diaphoretic and have an available history of diabetes more often than other patients with prehospital AMS, 25% of complete responders who are hypoglycemic would not receive D50W if it were used only in patients with "typical" clinical findings. Selective use of D50W for AMS is desirable because very few patients respond, but it is only feasible with concomitant field use of a rapid test of serum glucose.

Allied Health Personnel↗

PubMed1991

Prenatal diagnosis of a fetus with terminal deletion of chromosome 1 (q41)

Many authors have suggested that individuals affected by a terminal 1q deletion display a phenotypically definable and recognizable syndrome. In all of the 27 cases reported to date, the breakpoints were at band q42 or distally to it. To our knowledge, we report the first case of a terminal 1q41 deletion. Diagnosis was made prenatally by amniocentesis, following ultrasonographic diagnosis of omphalocele, cerebral ventriculomegaly, and increased nuchal fold thickness in a 19-week female fetus. Multiple facial and extremity features were consistent with the proposed distal 1q deletion syndrome; omphalocele, however, has not been reported previously. The absence of liver herniation into the omphalocele sac in this case supports the previously reported association of this finding with chromosomal anomalies.

Abnormalities, Multiple↗

PubMed1991

The empiric use of naloxone in patients with altered mental status: a reappraisal.

STUDY OBJECTIVE: To determine whether clinical criteria (respirations of 12 or less, mitotic pupils, and circumstantial evidence of opiate abuse) could predict response to naloxone in patients with acute alteration of mental status (AMS) and to evaluate whether such criteria predict a final diagnosis of presence or absence of opiate overdose as accurately as response to naloxone. CASES AND SETTING: Seven hundred thirty patients with AMS who received naloxone for diagnostic or therapeutic purposes at the discretion of two large, urban, paramedic base teaching hospitals. METHODS: We reviewed paramedic run sheets and audiotapes on all 730 patients as well as available hospital records of all patients who demonstrated any response to naloxone to determine whether overdose was responsible for their clinical presentations. We also reviewed hospital records for a selected sample of naloxone nonresponders. MAIN RESULTS AND CONCLUSION: Only 25 patients (3.4%) demonstrated a complete response to naloxone, whereas 32 (4.4%) manifested a partial or equivocal response. Nineteen of 25 complete responders (76%), two of 26 partial responders (8%) (with known final diagnosis), and four of 195 non-responders (2%) (with known final diagnosis) were ultimately diagnosed as having overdosed. Respirations of 12 or less or the presence of any one of the three clinical findings as a group were each highly sensitive in predicting response to naloxone, and at least as sensitive as response to naloxone in predicting a diagnosis of opiate overdose. Selective administration of naloxone for AMS would have decreased the use of this drug by 75% to 90% while still administering it to virtually all naloxone responders who had a final diagnosis of opiate overdose.

Clinical Protocols↗

PubMedDate not supplied

Comparison of the effects of immunosuppressive factors from newly established colon carcinoma cell cultures on human lymphocyte proliferation and cytokine secretion.

Tumor cells may influence the host's immune reactivity by the production of immunosuppressive factors (ISFs). In this study, the effects of ISFs derived from nine polyclonal colorectal carcinoma (CRC) cell lines on PHA-induced lymphocyte proliferation and cytokine secretion was investigated. We found that most of the culture supernatants (8/9) from CRC cell lines contained ISFs, which inhibited T cell proliferation to a variable degree in a dose-dependent manner. Comparison of T cell proliferation in the presence or absence of monocytes showed that monocytes can modulate the effects of tumor-derived ISFs on lymphocyte function. In addition, exposure of activated PBMC to the tumor cell supernatants resulted in an altered secretion of cytokines by these cells, i.e. the secretion of IFN-gamma was generally reduced while the secretion of IL-1beta, IL-2 and TNF-alpha was little affected. We further investigated the supernatants' inhibitory effects on PBMC in respect to the production of prostaglandin E(2) (PGE(2)). It was found that PGE(2) was secreted by all tumor cell cultures. Therefore this substance is probably involved in the immunosuppression in vivo. However, the secreted PGE(2) was shown not to be solely responsible for the observed suppression of lymphocyte proliferation in vitro. Our results suggest that the secretion of ISF is a common property of CRCs as demonstrated with newly established CRC cell cultures, and therefore this may also be an important immune escape mechanism of colonic carcinomas in vivo.

Cell Culture Techniques↗