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Biomedical subjects

C A Long

Publications and source records attributed to C A Long.

At least 19 recordsLinked to original sources
PubMed1999

Plasmodium: immunization with carboxyl-terminal regions of MSP-1 protects against homologous but not heterologous blood-stage parasite challenge.

A leading candidate for a vaccine targeted at the erythrocytic stages of plasmodial parasite development is the merozoite surface protein-1 (MSP-1). We have previously shown that the carboxyl-terminal region of MSP-1 derived from Plasmodium yoelii yoelii 17XL, expressed as a fusion protein with glutathione S-transferase (GST-PYC2), can immunize mice against an otherwise lethal homologous challenge infection. This protection has been shown to be predominantly mediated by antibodies. We report here on the efficacy of immunization with MSP-1 carboxyl regions when the challenge is a heterologous rodent parasite species. The course of parasitemia was not altered in mice immunized with GST-PYC2 and challenged with 10(4) heterologous Plasmodium chabaudi adami parasites, as both control and immunized mice developed infections that peaked at day 7 and then rapidly declined. Similarly, mice immunized with GST-PYC2 and challenged with 10(5) Plasmodium berghei ANKA parasites displayed virulence similar to that seen in infection control mice. The homologous region of the P. chabaudi adami MSP-1 gene was similarly expressed as a fusion protein with GST. Mice immunized with GST-PCC2 and challenged with 10(4) parasites showed significant protection against homologous P. chabaudi adami infection but no protection whatsoever against heterologous P. yoelii yoelii 17XL infection. These in vivo results correlate with the observation that sera generated by immunization with the carboxyl region of MSP-1 recognizes this protein from homologous, but not heterologous, radiolabeled parasite protein preparations.

Amino Acid Sequence↗
PubMed1998

Comparison of humoral immune responses elicited by DNA and protein vaccines based on merozoite surface protein-1 from Plasmodium yoelii, a rodent malaria parasite.

Immunization with DNA vaccines encoding relevant Ags can induce not only cell-mediated immune response but also humoral immune responses against pathogenic microorganisms in several animal models. Our previous results demonstrated that, when the C terminus (PyC2) of Plasmodium yoelii merozoite surface protein-1 (MSP-1), a leading vaccine candidate against erythrocytic stages of malaria, was expressed as a fusion protein (GST-PyC2) with glutathione S-transferase (GST), it elicited Ab-mediated protective immune responses in BALB/c mice. In our present study, we wished to examine the humoral responses to a DNA vaccine (V3) encoding GST-PyC2. The GST-PyC2 expressed in V3-transfected Cos 7 cells was recognized by a protective monoclonal Ab to PyC2 (mAb302), although the secreted product had undergone N-linked glycosylation. When BALB/c mice were immunized with V3 plasmid, anti-PyC2 Abs were successfully induced. These Abs immunoprecipitated native PyMSP-1 protein and competed with mAb302 for binding to its epitope at a level similar to those elicited by GST-PyC2 protein immunization. However, these Abs had significantly lower titers and avidities, and different isotype profiles and protective capacities against a lethal erythrocytic stage challenge, than those resulting from immunization with GST-PyC2 protein. Most surprising was the finding that, in contrast to protein immunization, there was no significant increase in the avidity of either GST-specific or PyC2-specific IgG Abs during the course of DNA immunization. This suggests that there may be little or no affinity maturation of specific Abs during DNA immunization in this system.

Animals↗
PubMed1998

Fc receptors are not required for antibody-mediated protection against lethal malaria challenge in a mouse model.

The mechanisms by which Abs mediate protection during blood-stage malaria infections is controversial, with some evidence pointing to the direct effect of Abs on parasite invasion and growth, while other studies suggest that Abs act in cooperation with monocytes to achieve parasite inhibition. To determine whether the effector phase of protection in vivo to the rodent parasite Plasmodium yoelii yoelii requires Fc receptor bearing cells, we passively transferred immune sera into FcR gamma-chain knockout mice. Inflammatory macrophages from these knockout mice were unable to mediate phagocytosis or Ab-dependent cell-mediated cytotoxicity (ADCC) through Fc gamma RI, Fc gamma RII, or Fc gamma RIII. Passive transfer of either P. y. yoelii hyperimmune sera or anti-GST-PYC2 sera directed to the major merozoite surface protein (MSP-1) of this parasite enabled both BALB/cByJ mice and FcR gamma-chain-deficient mice to resist lethal P. y. yoelii 17XL (Py17XL) challenge. mAb302, a protective IgG3 Ab, also passively protected both strains of mice. Most of these samples contain Ab isotypes that would not be able to protect mice if their protective effects required Ab-dependent cell-mediated cytotoxicity. These results establish that, in this infection, protection is directly mediated by Abs and does not require the participation of Fc receptors.

Animals↗
PubMed1998

Effects of L-triiodothyronine and the thyromimetic L-94901 on serum lipoprotein levels and hepatic low-density lipoprotein receptor, 3-hydroxy-3-methylglutaryl coenzyme A reductase, and apo A-I gene expression.

The mechanisms by which thyroid hormone (triiodothyronine (T3)) and a thyromimetic, 2-amino-3-(3,5-dibromo-4-[4-hydroxy-3-(6-oxo-1,6-dihydro-pyridazin -3-ylmethyl)-phenoxyl]-phenyl)propionic acid (L-94901), lower plasma low density lipoprotein (LDL) cholesterol and raise plasma high density lipoprotein (HDL) cholesterol levels was investigated in thyroidectomized and sham-operated rats. Thyroidectomy resulted in a 77% increase in plasma LDL cholesterol, a 60% decrease in plasma triglycerides, and a modest reduction in HDL cholesterol. Daily oral dosing with T3 (10-170 nmol/kg) or L94901 (100-1000 nmol/kg) for 7 days decreased plasma LDL cholesterol in thyroidectomized rats by 60-80%, respectively. This reduction in LDL cholesterol was accompanied by a dose-dependent increase in HDL cholesterol levels of up to 60%. Thus, the ratio of LDL to HDL was decreased from 1.01 to 0.12 after treatment with L-94901 and to 0.25 after dosing with T3. In sham-operated animals, T3 and L-94901 lowered LDL cholesterol by 61 and 46%, respectively, and increased HDL cholesterol by 25 and 53%, respectively. Immunoblotting analysis of liver membranes prepared from thyroidectomized or sham-operated rats demonstrated that LDL receptor protein levels were increased by up to eight-fold. Northern blotting analysis revealed similar large increases in hepatic LDL receptor mRNA levels that accounted for the increases in LDL receptor protein levels. Hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase mRNA, protein, and activity were increased 2- to 3-fold. The T3- and L-94901-mediated increases in serum HDL levels were associated with 2- to 3-fold increases in apo A-I mRNA levels. In contrast with most other hypocholesterolemic agents, T3 and L-94901 significantly increase HDL cholesterol levels in addition to decreasing LDL cholesterol levels due to induction of hepatic apo A-I and LDL receptor gene expression.

Animals↗
PubMed1998

Frequent detection of tumor cells in hematopoietic grafts in neuroblastoma and Ewing's sarcoma.

Many poor-risk neuroblastomas and tumours of the Ewing's sarcoma family (ET) recur despite autologous transplants. Recurrence may be due to tumor cells contained in the BM harvests or PBSC harvests. The objectives of this prospective study were to: (1) determine the incidence and degree of tumor cell contamination in paired BM and PBSC harvests; and (2) determine the efficacy of tumor cell purging by immunomagnetic CD34+ cell selection. 198 samples from 11 consecutive patients with neuroblastoma or Ewing's sarcoma were analyzed. We assayed tumor contamination by RT-PCR assay for PGP 9.5, plus immunohistochemistry for neuroblastoma-specific antigens (the latter in neuroblastoma only). None of these patients had tumor cells detected in their BM by clinical histology immediately before BM or PBSC harvests. However, 82% of PBSC and 89% of backup BM harvests were contaminated with tumor by RT-PCR and/or immunocytochemistry assays. Unselected PBSC and BM harvests contained similar quantities of tumor cells (median, approximately 200000 cells). Cyclophosphamide plus G-CSF mobilization did not affect the incidence or level of contamination in PBSC harvests, as compared to blood obtained before mobilization. Immunomagnetic CD34+ cell selection depleted tumor cells by a median of 3.0 logs for PBSC, and 2.6 logs for BM harvests.

Adolescent↗
PubMed1997

Dose-intensive vinorelbine with concurrent granulocyte colony-stimulating factor support in paclitaxel-refractory metastatic breast cancer.

PURPOSE: We evaluated weekly single-agent intravenous (IV) vinorelbine as salvage therapy for metastatic breast cancer. After the first five patients, all received elective growth factor support with granulocyte colony-stimulating factor (G-CSF; filgrastim) in an attempt to maximize delivered dose-intensity (DDI). Objective tumor response, DDI, and toxicity were assessed, as well as time to progression (TTP) and survival. PATIENTS AND METHODS: This single-center nonrandomized trial enrolled 40 patients. Anthracycline exposure and subsequent progression were common to all patients, and 38 of 40 were paclitaxel-refractory. Vinorelbine was given initially at 30 mg/m2/wk, then at 35 mg/m2/wk in a phase I/II design, which involved first intermittent (6 days of 7) and then continuous (daily) administration of G-CSF at 5 micrograms/kg. RESULTS: The maximum-tolerated starting dose was 35 mg/m2/wk with continuous G-CSF support. The mean DDI was 27.7 mg/m2/wk for all patients. There were two complete responses (CRs) and eight partial responses (PRs) in 40 assessable patients for an overall response rate of 25% (95% confidence interval [CI], 13% to 41%). The median TTP was 13 weeks and median survival time 33 weeks. The dose-limiting toxicity was neutropenia, with dose delay or reduction required in 14 of 27 patients entered at 35 mg/m2. Febrile neutropenia that required hospitalization was unusual (three of 40 patients, 8%). There were no treatment-related deaths. Grade 3/4 thrombocytopenia occurred in nine patients (23%) and 26 patients (65%) required RBC transfusions for anemia. Seven patients (18%) had reversible grade 3/4 nonhematologic complications, primarily related to neurotoxicity. Grade > or = 3 mucositis was absent. CONCLUSION: Concurrent administration of weekly vinoralbine and daily G-CSF is feasible and permits an increase in DDI for vinorelbine of 43% to 76% over that reported in series without growth factor support. The response rate, TTP, and survival data are encouraging for therapy given to heavily pretreated patients with metastatic breast cancer. Vinorelbine is not cross-resistant with paclitaxel and should be considered for further trials in the dose-intensified mode made possible by G-CSF, alone or combined with other agents.

Adult↗
PubMed1996

Plasmodium yoelii: the role of the individual epidermal growth factor-like domains of the merozoite surface protein-1 in protection from malaria.

The merozoite surface protein-1 (MSP-1) is a leading candidate for a vaccine targeted at the erythrocytic stages of plasmodial parasite development. Recently, there has been increasing interest in this polypeptide, particularly in the carboxyl-terminal EGF-like domains. We have previously shown that this region from Plasmodium yoelii, when expressed in native configuration, could immunize mice against an otherwise lethal challenge infection. In this model system, protection appears to be predominantly mediated by antibodies. In all rodent immunization studies to date, however, the immunogen has contained both of the postulated EGF-like domains. We report here on the efficacy of immunization with the individual EGF-like domains from P. yoelii in elicitation of a protective host response. Although all animals developed some level of antibody in response to the various immunogens, only those animals immunized with both EGF-like domains produced antibodies which could recognize the native MSP-1 molecule. Antibodies generated against the individual EGF-like domains did cross-react with the double EGF-like domain structure, suggesting that the immunogens had retained elements of native configuration. In addition, only those animals which generated antibodies capable of recognizing native MSP-1 showed any level of protection from challenge infection. These results suggest that determinants unique to the double EGF-like domain structure may be necessary for the generation of antibodies specific for the native configuration of MSP-1 and that these antibodies may play a significant role in protection.

Animals↗
PubMed1996

Maternal serum creatine kinase does not predict tubal pregnancy.

PURPOSE: Our purpose was to validate prospectively the predictive value of maternal serum creatine kinase in the evaluation of ectopic pregnancy. METHODS: Fifty-one consecutive pregnant first-trimester patients who presented for suspected abnormal pregnancy were enrolled. Maternal serum samples were obtained and assayed for creatine kinase. Patients were subsequently evaluated for abnormal pregnancy by serial quantitative hCG levels, transvaginal ultrasonography, and surgery when appropriate. A receiver operating characteristic (ROC) curve was generated comparing intrauterine to extrauterine (ectopic) pregnancy. RESULTS: Of 51 patients, 18 had an ectopic pregnancy, 16 had a spontaneous abortion, and 17 had an ongoing intrauterine pregnancy. The ROC curve revealed that maternal serum creatine kinase had no ability to predict ectopic pregnancy. CONCLUSIONS: Maternal serum creatine kinase is not a reliable predictor of tubal pregnancy.

Biomarkers↗
PubMed1996

Evaluation of patients with abnormal uterine bleeding.

An accurate, efficient diagnosis of disorders responsible for abnormal uterine bleeding depends on a systematic consideration of all the possible causes. Careful history and physical and pelvic examinations provide the framework for evaluation. Many adjunctive diagnostic aids can be used to evaluate women with abnormal uterine bleeding. These tests include complete blood cell count, pregnancy test, hormone levels (estradiol, progesterone, follicle-stimulating hormone, luteinizing hormone, prolactin, testosterone, dehydroepiandrosterone sulfate), thyroid function tests, liver function tests, and coagulation profile. The need for these tests are individualized and based primarily on the patient's presentation. In women of reproductive age a complication of pregnancy should always be ruled out. Ectopic pregnancies can be life threatening. The prognosis in women with trophoblastic disease can be altered by a delay in establishing the correct diagnosis. Ultrasonographic studies, particularly transvaginal ultrasonography and hysteroscopy, have played an increasing role in the evaluation of patients with abnormal uterine bleeding over the past decade, especially for cases of intrauterine space-occupying lesions, including endometrial polyps, submucosal myomas, and retained placental fragments. Suspicion of reproductive tract malignancies is heightened in patients > 35 years old, those with a history of oligoovulation or anovulation suggestive of long-term unopposed estrogen exposure, those who are obese, and those who do not respond to first-line medical management. Diagnostic techniques available for the evaluation of these cases include endometrial biopsy, dilatation and curettage, transvaginal ultrasonography, and hysteroscopy. These procedures not only allow accurate diagnosis but may permit immediate therapeutic measures to be taken when organic causes are discovered. In summary, the key to the evaluation of abnormal uterine bleeding is a through history and physical and pelvic examinations governed by the differential diagnosis of excessive uterine bleeding and the selected use of adjunctive diagnostic tests and procedures only when absolutely necessary.

Diagnosis, Differential↗
PubMed1996

Protective efficacy against malaria of a combination sporozoite and erythrocytic stage vaccine.

Most malariologists believe that optimal malaria vaccines will induce protective immune responses against different stages of the parasite's life cycle. A multiple antigen peptide (MAP) vaccine based on the Plasmodium yoelii circumsporozoite protein (PyCSP) protects mice against sporozoite challenge by inducing antibodies that prevent sporozoites from invading hepatocytes. A purified recombinant protein vaccine based on the P. yoelii merozoite surface protein-1 (PyMSP-1) protects mice against challenge with infected erythrocytes, presumably by inducing antibodies against the erythrocytic stage of the parasite. We now report studies designed to determine if the PyMSP-1 vaccine protects against challenge with sporozoites, the stage encountered in the field, and if immunization with a combination of the PyCSP and PyMSP-1 vaccines provides additive or synergistic protection against sporozoite challenge. In two experiments, using TiterMax or Ribi R-700 as adjuvant, 3 of 19 mice immunized with the PyMSP-1 vaccine were completely protected against sporozoite challenge. The remaining mice had significantly delayed onset and lower levels of peak parasitemia than did control mice (11.1 +/- 2.8% vs. 36.7 +/- 1.6% in experiment #2, P < 0.01). Immunization with the combination vaccine reduced by approximately 50% the level of antibodies induced to PyCSP and PyMSP-1, as compared to that induced by the individual components. However, in two experiments, there was evidence of additive protection. Six of 19 (31.6%) immunized with the PyCSP vaccine, 3 of 19 (15.8%) immunized with the PyMSP-1 vaccine, and 10 of 19 (52.6%) immunized with the combination were completely protected against sporozoit challenge. This modest increase in protection in the combination group may be a reflection of additive anti-PyCSP and anti-PyMSP-1 immunity, since mice in the combination group had diminished levels of antibodies to each components. These studies indicate that considerable work may be required to optimize the construction, delivery, and assessment of multi-stage malaria vaccines.

Animals↗
PubMed1996

Comparison of immunosuppressive properties of hydatidiform mole decidua and trophoblast extracts.

PROBLEMS: The immunologic privilege afforded the fetus relies upon immunoregulation within the maternal-fetal interface. Trophoblast and decidua-derived immunoregulatory factors enforce this privilege by locally suppressing maternal responses to trophoblast antigens. The relative contribution of trophoblast or decidua immunosuppressive factors to pregnancy immunotolerance are not well characterized. The purpose of this study was to compare the suppressive effects of hydatidiform mole trophoblast and decidua extracts on interleukin-2-dependent proliferation. METHOD: Tissue extracts were prepared from hydatidiform mole trophoblast and decidua following uterine evacuation. Samples were submitted to interleukin-2-dependent and -independent cell proliferation assays. RESULTS: Hydatidiform mole trophoblast extract significantly (P < 0.05) suppressed interleukin-2-dependent proliferation but did not affect interleukin-2-dependent cell proliferation. In contrast, molar decidua extract suppressed both cell lines. CONCLUSIONS: Human hydatidiform mole trophoblast contains factor(s) that specifically abrogate interleukin-2-dependent clonal expansion of murine cytotoxic T-cells. In contrast, extracts of molar decidua suppressed both interleukin-2-dependent and -independent responses. This indicates that the trophoblast antagonizes critical interleukin-2-mediated immunologic responses, but that the decidua uses nonspecific antiproliferative mechanisms for immunoregulation.

Decidua↗
PubMed1996

Influence of adjuvants on protection induced by a recombinant fusion protein against malarial infection.

Previously, we described a protective immune response induced by the carboxyl-terminal region of the merozoite surface protein-1 (MSP-1) from the rodent malarial parasite Plasmodium yoelii yoelii 17XL, expressed as a fusion protein and designated glutathione S-transferase (GST)-PYC2. We also demonstrated that the humoral response induced by GST-PYC2 was the primary mechanism by which immunized animals controlled their blood-stage infections. We have now examined the influence of several adjuvants on the immune response to the GST-PYC2 fusion protein. While alum, Freund's adjuvant, Ribi adjuvant system, and TiterMax were efficacious in eliciting a protective response with GST-PYC2 in BALB/c mice, saponin failed to induce protection, although significant levels of PYC2-specific antibodies were produced in all immunized animals. This protection depended on the mouse strain since immunization of Swiss Webster mice with GST-PYC2 in alum did not produce levels of PYC2-specific antibodies comparable to those in BALB/c mice nor did it induce any demonstrable level of protection against parasite challenge. Swiss Webster mice were protected, however, when immunized with GST-PYC2 in other adjuvants. Immunization with PYC2, isolated free of GST induced lower levels of antigen-specific antibody; only those animals given PYC2 in Freund's adjuvant demonstrated a significant degree of protection, suggesting the possibility (of additional cellular effector mechanisms. These findings demonstrate that adjuvant, host genotype, and the fine specificity of the response significantly influence the protection induced by the carboxyl terminus of MSP-1 in vivo and illustrate the need to consider these factors in evaluating MSP-1 as a vaccine component.

Adjuvants, Immunologic↗
PubMed1995

Humoral response to a carboxyl-terminal region of the merozoite surface protein-1 plays a predominant role in controlling blood-stage infection in rodent malaria.

The developmental stages of malaria parasites that infect E are responsible for the morbidity and mortality associated with this disease. One of the leading candidates for a blood-stage vaccine against malaria is a surface protein of merozoites, the infectious stages for E, designated merozoite surface protein-1 (MSP-1). The rodent malarial parasite Plasmodium yoelii yoelii (Py) has provided a model system for the study of this Ag, and previous studies from our laboratory had demonstrated that the carboxyl-terminal, cysteine-rich region of MSP-1, when expressed in a native configuration, could immunize mice against a normally lethal challenge infection with Py. We have now prepared a new fusion construct with the glutathione-S-transferase gene of Schistosoma japonicum joined to the carboxyl-terminal 11 kDa of Py MSP-1. This includes only the two epidermal growth factor-like domains of the MSP-1 protein. When expressed in recombinant Escherichia coli, the fusion protein induces a strong protective response in BALB/c mice as judged by the resistance of immunized animals to a virulent challenge infection. Moreover, we demonstrate that this resistance can be transferred passively by immune serum or by purified Ig, establishing a significant role for humoral immunity in protection. No role for CD4+ or CD8+ T cells could be identified in the first 12 days after challenge infection in immune mice selectively depleted of these cells; however, after this time, parasitemias gradually increased in mice depleted of CD4+ T cells, suggesting an active host response is necessary to completely eliminate the infection.

Animals↗
PubMed1995

One artificial insemination per cycle with donor sperm is as efficacious as two inseminations.

PURPOSE: To compare pregnancy rates per treatment cycle of artificial inseminations with donor sperm in patients receiving one versus two inseminations. METHODS: Retrospective cross-sectioned analysis of 167 patients who underwent 869 cycles receiving one or two donor inseminations were reviewed from 1987 through 1993 at our institution. RESULTS: A total of 256 cycles with one donor insemination per cycle resulted in 21 pregnancies and a cycle of fecundity of 8.2%, and 613 cycles with two donor inseminations resulted in 35 pregnancies and a cycle fecundity of 5.7%. Life table and logistic cumulative probability analysis of pregnancy occurrence showed no difference between treatment groups. CONCLUSIONS: These data suggest there are no important clinical differences of cycle fecundity or cure rate in one versus two inseminations with donor sperm. Economic costs of two inseminations may not be justified.

Cross-Sectional Studies↗