Biomedical subjects

S H Ip

Publications and source records attributed to S H Ip.

At least 19 recordsLinked to original sources

PubMed2003

Rapid induction of apoptosis in human keratinocytes with the photosensitizer QLT0074 via a direct mitochondrial action.

QLT0074 is a newly introduced, porphyrin-derivative for use in photodynamic therapy (PDT). In the current study, the intracellular distribution of QLT0074 and the mode of cell death induced by photosensitization with this compound in vitro were assessed for transformed human HaCaT keratinocytes. Fluorescence microscopy studies indicated a distribution of the drug to the cytoplasm, nuclear membrane and mitochondria of these cells. In the absence of light, QLT0074 produced no evidence of apoptosis-related biochemical changes or affected cell viability. When combined with blue light exposure, cytotoxicity was exerted in a QLT0074- and light-dose-related manner. Appearance of the mitochondrial protein cytochrome c in the cytosolic fraction and expression of the apoptosis-associated mitochondrial 7A6 antigen were demonstrable following photosensitization at nano-molar levels of QLT0074. Evidence of processing of the apoptosis-effector molecules caspase-3, -6, -7, -8 and -9 as well as cleavage of the caspase-3 substrate poly (ADP-ribose) polymerase (PARP) were demonstrable subsequent to cytochrome c release after PDT. Treatment with the anti-oxidant pyrrolidine dithiocarbamate (PDTC) inhibited cytochrome c release, caspase-3 activation and PARP cleavage associated with PDT thereby supporting the contention that QLT0074 induces apoptosis through the generation of reactive oxygen species upon light activation. QLT0074 is a potent photosensitizer with the capacity to directly initiate apoptosis by acting upon mitochondria.

Antioxidants↗

PubMed1998

(+/-)-trans-2-[3-methoxy-4-(4-chlorophenylthioethoxy)-5-(N-methyl-N- hydroxyureidyl)methylphenyl]-5-(3,4, 5-trimethoxyphenyl)tetrahydrofuran (CMI-392), a potent dual 5-lipoxygenase inhibitor and platelet-activating factor receptor antagonist.

By incorporating an N-hydroxyurea functionality onto diaryltetrahydrofurans, a novel series of compounds was investigated as dual 5-lipoxygenese (5-LO) inhibitor and platelet-activating factor (PAF) receptor antagonist. These dual functional compounds were evaluated in vitro for 5-LO inhibition in RBL cell extracts and human whole blood, and PAF receptor antagonism in a receptor binding assay. PAF-induced hemoconcentration and arachidonic acid- and TPA-induced ear edema in mice were used to determine in vivo activities. The structure-activity relationship analysis to define a preclinical lead is presented. (+/-)-trans-2-[3-methoxy-4-(4-chlorophenylthioethoxy)-5-(N-methyl- N-h ydroxyureidyl)methylphenyl]-5-(3,4, 5-trimethoxyphenyl)tetrahydrofuran (40, CMI-392) was selected for further study. In the arachidonic acid-induced mouse ear edema model, 40 was more potent than either zileuton (a 5-LO inhibitor) or BN 50739 (a PAF receptor antagonist), and it demonstrated the same inhibitory effect as a physical combination of the latter two agents. These results suggest that a single compound which both inhibits leukotriene synthesis and blocks PAF receptor binding may provide therapeutic advantages over single-acting agents. The clinical development of compound 40 is in progress.

Animals↗

PubMed1991

Recombinant soluble human complement receptor type 1 inhibits inflammation in the reversed passive arthus reaction in rats.

The human CR1 was genetically engineered by site directed mutagenesis into a truncated form which was secreted from transfected Chinese hamster ovary cells. This soluble recombinant CR1 (sCR1) was purified from the supernatants of the Chinese hamster ovary cells cultured in a hollow fiber bioreactor. sCR1 inhibits the C3 and C5 convertases of the classical and the alternative pathways in vitro. The ability of sCR1 to inhibit the immune complex-mediated inflammation in vivo was tested in a rat reversed passive Arthus reaction model. Administration of sCR1 at the dermal sites reduced the Arthus vasculitis in a dose-dependent manner as judged by both gross and microscopic examination, as well as by immunohistologic localization of C3 and C5b-9 neoantigen deposits. These data suggest that sCR1 inhibits the Arthus reaction by interrupting the activation of the C cascade, hence limiting the detrimental immune complex-induced tissue damage in vivo.

Animals↗

PubMed1990

Soluble interleukin-2 receptor: elevated levels in serum and synovial fluid of patients with rheumatoid arthritis.

Soluble interleukin-2 receptor (sIL-2R) levels were quantitated in the serum and synovial fluid (SF) of patients with rheumatoid arthritis (RA) and degenerative joint disease (DJD). A sandwich immunoassay, employing two monoclonal antibodies against distinct epitopes on the IL-2R, was utilized for measurement. We found a striking elevation of sIL-2R in RA SF as compared with DJD SF (RA, 1319 +/- 135; DJD, 416 +/- 59; p less than 0.001). RA serum sIL-2R levels were also significantly elevated over DJD levels. There was no interaction between rheumatoid factor (RF) and sIL-2R. RA patients with elevated sIL-2R levels had significantly longer disease duration, higher c-reactive protein (CRP) levels in serum and SF, and higher RF levels in serum and SF. The groups were similar in regard to other laboratory variables. The presence of elevated levels of sIL-2R in RA serum and SF confirms the presence of a heightened immune reactivity and in vivo activation of lymphocytes in RA.

Arthritis, Rheumatoid↗

PubMed1990

Elevated soluble CD8 in the synovial fluid from patients with rheumatoid arthritis.

Suppressor/cytotoxic T cells express the surface marker CD8, which can be measured in a soluble form in culture supernatants of activated human lymphocytes. Using a sandwich immunoassay, we assessed the levels of soluble CD8 (sCD8) in serum from patients with rheumatoid arthritis (RA; n = 82), patients with degenerative joint disease (DJD; n = 40), and healthy controls. There were no differences in serum sCD8 levels among these groups. In contrast, the levels of soluble CD8 in the synovial fluid (SF) from patients with RA (n = 53) were significantly increased compared with the levels in 23 samples from patients with DJD (821 +/- 110 U/ml versus 213 +/- 13 U/ml, p less than 0.001). Synovial fluid sCD8 levels in the RA group were strikingly elevated, to a maximum value of 5,026 U/ml. In the majority of RA SF specimens (39 of 53), the values were significantly higher in the SF than the serum. Although the RA group had higher values of sCD8, such values were not significantly correlated with measured laboratory or clinical parameters. Current clinical and laboratory methods of evaluating patients may not be adequate in dealing with the complexity and heterogeneity of RA. Soluble CD8 values may be useful in further grouping patients with this disease.

Antibodies, Monoclonal↗

PubMed1989

Soluble CD8 during T cell activation.

The CD8 Ag has long been used as a surface marker for the identification of cytotoxic and suppressor cells. Recently CD8-positive cells have been shown to release a soluble form of the CD8 Ag. We have devised a sandwich monoclonal enzyme immunoassay for the quantitation of this released CD8. Soluble CD8 was released in response to lymphocyte activation. In vitro, PHA or anti-CD3 mAb-mediated T cell activation led to release of CD8 into the culture supernatant. In vivo, serum from patients with EBV-induced infectious mononucleosis (IM), a disease associated with intense CD8+ T cell activation, demonstrated elevations in soluble CD8 (7939 U/ml, day 0) compared to serum from normal controls (289 U/ml). Levels of soluble CD8 correlated (r = 0.82, p less than 0.001) with the increased percentage of CD8+/HLA-DR+ (activated CD8+ T cells) observed in acute IM. Sequential analysis of serum during the course of IM shows that soluble CD8 levels parallel the decline in CD8+/HLA-DR+ cells that occurs with the resolution of the disease. These data suggest that released CD8 may be of value in monitoring the involvement of CD8+ T cells in response to a pathologic event. The functional role of the released CD8 molecule will require further investigation.

Adolescent↗

PubMed1989

Two distinct immunogenic epitopes on the alpha chain of human T cell antigen receptor.

Monoclonal antibodies (MAb) to human T Cell Antigen Receptor (TCR) have been used to study the structure and function of TCR. Using purified alpha/beta heterodimeric protein, we have generated two MAb against human TCR alpha protein. The two MAb, alpha F1 and alpha F2, recognized amino acid residues 141-159 and 212-231 of the constant region of the alpha chain TCR. Although neither MAb reacted with viable T cells, both antibodies immunoprecipitated TCR alpha/beta heterodimer from HPB-ALL, Jurkat, PBL and a 32 kDa in vitro translation product of alpha chain cDNA. These antibodies have been shown to be useful in the immunohistochemical staining of human tissues. These two MAb, together with other anti-framwork MAb to TCR, should provide valuable reagents in the study of TCR and clinical classification of T cell lineage neoplasms.

Antibodies, Monoclonal↗

PubMed1989

A critical analysis of serum and urine interleukin-2 receptor assays in renal allograft recipients.

A component of the interleukin 2 receptor (IL-2R) is released in soluble form during T cell activation and can be detected in the blood during acute renal allograft rejection. This study evaluates the diagnostic utility of a sandwich enzyme immunoassay test for serum and urine IL-2R in renal allograft recipients. A rise in serum IL-2R during the week prior to the clinical diagnosis of rejection correlated better with rejection than did isolated serum IL-2R levels or urine values. For the diagnosis of acute rejection, a rise in serum IL-2R (sensitivity 73%, specificity 87%) was comparable in overall test performance to a rise in serum creatinine (sensitivity 70%, specificity 84%). Overall, the two tests had equivalent receiver operating characteristic curves. Because the etiology of false positives in creatinine and IL-2R assays differed (primarily cyclosporine toxicity and infection, respectively), the predictive value of the combined tests was superior to either alone.

Creatinine↗

PubMed1989

Increased serum CD8 antigen level in childhood Hodgkin's disease relates to advanced stage and poor treatment outcome.

Measurement of the soluble form of CD8 antigen, a surface membrane component of suppressor/cytotoxic T cells, has yielded useful information relevant to prognosis in the lymphoid malignancies of childhood. We therefore determined pretreatment levels of serum CD8 antigen in 90 children with newly diagnosed Hodgkin's disease. The findings ranged widely, from 220 to 2,585 U/mL (median, 556 U/mL). In patients with advanced disease (stage III or IV), the median serum CD8 level was significantly higher than in those with less disease extension (stage I or II): 675 v 477 U/mL, P = .003. It was also higher in children with B symptoms compared with all others: 622 v 494 U/mL, P = .005. Cases with a histologic classification of mixed cellularity had a significantly higher median level of the antigen than did those classified as nodular sclerosis: 847 v 509 U/mL, P = .005. Finally, higher serum CD8 levels (greater than 430 U/mL) were significantly associated with an increased probability of treatment failure (P = .02). In a multivariate analysis, serum CD8 level retained its impact on treatment outcome after adjustment for other potentially useful prognostic factors, including disease stage, presence of B symptoms, histology, erythrocyte sedimentation rate, sex, age, and race. The prognostic strength shown by soluble CD8 in this analysis suggests that the antigen has clinical value. We postulate that increased CD8 levels in serum indicate enhanced suppressor T-cell activity, which may compromise the host's antitumor immunity, leading to unusually aggressive disease.

Adolescent↗

PubMed1989

High serum interleukin-2 receptor levels correlate with a poor prognosis in children with Hodgkin's disease.

To improve the biologic evaluation of Hodgkin's disease, we determined serum interleukin-2 receptor (IL2R) levels in 88 children with this tumor. In patients with stage III or IV disease, the median receptor level was significantly higher than in patients with lower stages (3195 vs. 1087 U/ml, p = 0.0001). Similarly, the median level for children with stage B disease was 3262 U/ml, compared with 999 U/ml for those lacking constitutional symptoms (p = 0.0001). Patients with very high soluble IL2R levels (greater than or equal to 5000 U/ml) were significantly more likely to fail treatment (p = 0.01), even when the analysis was restricted to groups with advanced disease: stages III and IV (p = 0.0001). When entered in the Cox-proportional hazards model with other potentially useful prognostic factors, soluble IL2R level was found to be an independent predictor of treatment outcome. The relationship of high serum IL2R levels to an adverse clinical outcome in Hodgkin's disease may be explained by a model in which the soluble receptor competes for the ligand with the cellular receptor on normal lymphocytes, thus blocking antitumor immunity dependent on interleukin-2. Alternatively, high serum levels of IL2R may simply reflect increased release of the receptor from activated malignant cells in patients with advanced disease or an otherwise poor prognosis.

Adolescent↗

PubMed1988

Signal transduction of gamma/delta T cell antigen receptor with a novel mitogenic anti-delta antibody.

Human T lymphocytes express either alpha/beta- or gamma/delta-TCR in association with the CD3 complex. We have isolated a mAb, delta TCS1, that immunoprecipitated the gamma/delta-TCR heterodimer from cell lysates of Peer and Molt-13 leukemia cell lines. After dissociation of the gamma- and delta-chains of TCR by treatment with SDS, delta TCS1 specifically immunoprecipitated the delta-chain. This antibody bound to the surface of other gamma/delta-positive T cell lines and clones and was able to stimulate the proliferation of a minor cell population (0.9 to 4.0%) of resting human PBL. Upon binding to gamma/delta-TCR-bearing Molt-13 cells and PBL, delta TCS1 elicited a fura-2 Caa+ signal indicating that the gamma/delta-receptor is functionally similar to the alpha/beta-heterodimer. These data indicate that the delta TCS1 antibody recognizes an epitope on TCR delta-chain and its mitogenic activity should be useful in characterizing the functional properties of human gamma/delta-positive T lymphocytes.

Animals↗

PubMed1988

Soluble interleukin 2 receptors in patients with malignant lymphoma.

We performed a retrospective analysis of serum interleukin 2 receptor (IL-2R) levels in a group of 35 patients with malignant lymphoma (ML; 13 T cell and 22 B cell) using a new enzyme immunoassay. Our objectives were to determine if elevated levels of soluble IL-2R occur in patients with active ML, whether serum IL-2R levels are prognostic, and whether prospective studies are warranted. Our preliminary data indicate that serum IL-2R levels correlate with disease activity and size of tumor, but not with grade or stage of the tumor. Five-year actuarial survival was 20% for patients with IL-2R levels greater than 1000 U/mL at any time during their course and 86% for patients who did not exceed that threshold. Furthermore, patients with IL-2R levels lower than 1000 U/mL were more likely to achieve a complete remission. Serum lactate dehydrogenase and uric acid levels did not show significant correlation with disease activity or prognosis. We conclude that serum IL-2R levels may have clinical and prognostic significance in patients with ML and that prospective studies are indicated.

Antibodies, Viral↗

PubMed1988

Soluble interleukin 2 receptors in sera of Japanese patients with adult T cell leukemia mark activity of disease.

Serum concentrations of soluble interleukin 2 receptors (sIL 2R) were measured by an enzyme-linked immunosorbent assay (ELISA) in 30 patients with adult T cell leukemia (ATL), in 9 patients with other hematopoietic malignancies, and in 17 asymptomatic individuals seropositive for human T cell leukemia virus type I (HTLV-I). Sixty HTLV-I seronegative, age-matched controls showed a normal range of form 63.2 to 480.8 U/mL. All asymptomatic carriers of HTLV-I had sIL 2R in their sera within the normal range. sIL 2R in sera was not related to the anti-HTLV-I antibody titer. Eleven patients with acute ATL, a clinical phenotype with median survival rate of 4.4 months, had markedly elevated sIL 2R (11,100 to 99,000 U/mL), but eight patients with smoldering ATL had low sIL 2R values (less than 480.8 U/mL) comparable to controls. Eleven patients with chronic ATL had intermediate elevated levels of sIL 2R (480.8 to 37,300.0 U/mL). Serum levels of sIL 2R correlated with the number of ATL cells (r = 0.812) and CD25-positive cells (r = 0.725) circulating in the peripheral blood. Longitudinal studies performed in four patients with ATL showed significant correlation between serum concentration of sIL 2R and activity of the malignancy. These findings suggest that the level of sIL 2R in serum indicated tumor load and, possibly, prognosis.

Adult↗

PubMed1988

Serum levels of CD8 antigen in childhood lymphoid malignancies: a possible indicator of increased suppressor cell activity in poor-risk patients.

Serum concentrations of CD8 antigen were measured at diagnosis with an enzyme-linked immunoassay in children with acute lymphoblastic leukemia (n = 344) or non-Hodgkin's lymphoma (n = 65). All patients had detectable levels of the serum antigen, which in its soluble nonreduced form appeared to be a 52-Kd homodimer as compared with the 66-Kd surface membrane component on most thymocytes and on a subset of functionally distinct T cells (suppressor/cytotoxic). Increased serum levels of CD8 in leukemia patients were significantly related to recognized high-risk prognostic features: high leukocyte count, large liver and spleen size, high serum lactic dehydrogenase level, T-cell immunophenotype, presence of a mediastinal mass, pseudodiploid karyotype, DNA index less than 1.16, and chromosomal translocation. Children with serum CD8 levels greater than or equal to 450 U/mL were more likely to fail treatment than were those with lower levels (P = .002), even in the group with non-T-cell leukemia (P = .003). In a multivariate analysis, serum CD8 antigen contributed independent prognostic information beyond that conveyed by age, leukocyte count, and race (P = .02). High serum CD8 antigen levels also correlated with advanced stages of disease in children with non-Hodgkin's lymphoma or B-cell leukemia. Children with higher serum CD8 antigen levels (greater than or equal to 700 U/mL) had a poorer treatment outcome (P = .003), even after results were adjusted for disease stage and serum lactic dehydrogenase level (P = .05). Measurement of serum levels of CD8 antigen not only has important prognostic value in childhood lymphoid malignancies but also could be useful in assessing the immunoregulatory role of T cells in patients with cancer.

Adolescent↗

PubMed1988

Serum interleukin 2 receptor levels in childhood acute lymphoblastic leukemia.

The clinical significance of interleukin 2 receptor (IL2R) concentrations in serum was determined for 344 children with newly diagnosed acute lymphoblastic leukemia (ALL). Serum levels of IL2R in patients (267 to 80,000 U/mL, median 2,007 U/mL) were significantly higher than normal control values (170 to 738 U/mL, median 347 U/mL) (P less than .0001). Measurements in cases of T cell ALL were lower than in the non-T, non-B cases (P = .02). Among the 264 patients with non-T, non-B ALL, but not in those with T cell disease, higher serum IL2R levels (greater than 2,000 U/mL) were associated with a poorer treatment outcome (P = .04). In a multivariate analysis, serum IL2R level contributed independent prognostic information beyond that conveyed by leukocyte count, race, and age (P = .04). One explanation for these results is that soluble IL2R competes with normal lymphocyte-integrated IL2R for the ligand and thus could suppress host antitumor immunity.

Adolescent↗

PubMed1987

Plasma interleukin 2 receptor levels in renal allograft recipients.

Shed/soluble interleukin 2 receptor (IL2R) was measured by an enzyme-linked immunosorbent assay (ELISA) in serial samples of plasma from 32 patients with renal allografts. Patients on chronic dialysis (pretransplant) had elevated IL2R levels which fell toward normal after transplantation. Patients with acute rejection and viral infection had significantly higher levels of plasma IL2R than did patients with stable renal function or with cyclosporine nephrotoxicity (all P less than 0.005). Acute renal failure from other causes (renal artery stenosis, hemolytic-uremic syndrome) did not have a comparable rise in IL2R. The assay of shed/soluble IL2R may have diagnostic value in the clinical management of allograft recipients, a possibility that deserves further clinical evaluation.

Antibodies, Monoclonal↗

PubMed1987

High serum interleukin-2 receptor levels are related to advanced disease and a poor outcome in childhood non-Hodgkin's lymphoma.

The clinical usefulness of serum interleukin-2 receptor (IL2R) measurements was determined in 59 children with non-Hodgkin's lymphoma (NHL) and six with B cell acute lymphoblastic leukemia (B-ALL). Levels of the receptor showed a clear relationship to disease stage, as follows: B-ALL greater than stage III or IV diffuse small noncleaved-cell NHL greater than stage III or IV lymphoblastic NHL greater than stage I or II NHL. Soluble IL2R levels were also closely correlated with serum lactic dehydrogenase levels (r = 0.7, P = .0001), a recognized indicator of tumor cell burden. Children with higher soluble IL2R levels (greater than 1,000 U/mL) were significantly more likely to fail treatment (P = .001), even when the analysis was limited to those with more advanced disease: stages III and IV NHL and B-ALL (P = .02). In a multivariate analysis, soluble IL2R level was found to have greater predictive strength than either serum lactic dehydrogenase level or disease stage. Thus, the measurement of soluble IL2R in children with NHL could be expected to improve existing methods of risk assignment in this disease.

Acute Disease↗

PubMed1983

Rapid identification and detection of parasitized human red cells by automated flow cytometry.

Rapid and reliable identification of various human red cells parasites is important in many chemotherapeutic and immunologic studies. Because manual microscopic counting is tedious and imprecise, we have developed a simple diagnostic procedure for the automated flow cytometric detection of in vitro infected red cells, using a nucleic acid-binding fluorescent dye, acridine orange. Human malaria (Plasmodium falciparum)-infected red cells from continuous human erythrocyte culture were incubated at room temperature in acridine orange stain for 5 min after which the samples were analyzed by flow cytometry. Since mature red cells contain no DNA, infected red cells were identified with a distinct fluorescent signal. A total of 200,000 cells per sample were counted and analyzed in less than 2 min. Rings, trophozoites, and schizonts were assessed and identified in synchronized infected red cell cultures by flow cytometry. In addition, various stages of infected red cells were isolated with a cell sorter. This rapid method permits accurate and reliable assessment of data with the exclusion of anomalous data such as damaged cells, extraneous material, and contaminating particles.

Acridine Orange↗