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Biomedical subjects

R L Roberts

Publications and source records attributed to R L Roberts.

At least 37 records · Page 2Linked to original sources
PubMed1999

Immune thrombocytopenia after umbilical cord progenitor cell transplant: response to vincristine.

An 8-month-old male with X-linked lymphoproliferative disease underwent an unrelated, partially matched (with major mismatch at DR locus), cord blood stem cell transplant. Four months following the transplant, he developed immune thrombocytopenia with hemolytic anemia (Evans syndrome). He received multiple courses of intravenous immunoglobulin, anti-Rh D immunoglobulin, a pulse of high-dose corticosteroids and cyclosporine with some improvement of hemolytic anemia, but no improvement of the thrombocytopenia. Addition of vincristine, resulted in long-term resolution of thrombocytopenia and anemia. No major toxicity was observed during treatment. Vincristine should be considered as a treatment for refractory immune thrombocytopenia after hematopoietic stem cell transplantation.

Fetal Blood↗
PubMed1999

Prolonged mating in prairie voles (Microtus ochrogaster) increases likelihood of ovulation and embryo number.

Prairie voles are induced ovulators that mate frequently in brief bouts over a period of approximately 24 h. We examined 1) impact of mating duration on ovulation and embryo number, 2) incidence of fertilization, 3) temporal pattern of embryo development, 4) embryo progression through the reproductive tract over time, and 5) embryo development in culture. Mating was videotaped to determine first copulation, and the ovaries were examined and the reproductive tracts flushed at 6, 8, 10, 12, 16, 20, and 24 h and 2, 3, and 4 days after first copulation. The number of mature follicles and fresh corpora lutea and the number and developmental stage of embryos were quantified. One, two-, and four-cell embryos were cultured in Whitten's medium. Mature follicles were present at the earliest time examined (6 h). Thirty-eight percent of females that had been paired for < 12 h after the first copulation ovulated, whereas all females paired >/= 12 h after the first copulation ovulated. Virtually all (> 99%) oocytes recovered from females paired for >/= 12 h after first copulation were fertilized. Pairing time after first copulation and mean copulation-bout duration were significant (p < 0.05) determinants of embryo number. Embryos entered the uterine horns and implanted on Days 3 and 4, respectively, after first copulation (Day 0). Embryos cultured in vitro underwent approximately one cell division per day, a rate similar to that in vivo. We conclude that prairie voles ovulate reliably after pairing for >/= 12 h, although some females showed exceptional sensitivity not predicted by the variables quantified. Prolonged mating for longer than 12 h increased the total embryos produced. This mechanism likely has adaptive significance for increasing offspring number.

Animals↗
PubMed1999

Endosome fusion in living cells overexpressing GFP-rab5.

CHO and BHK cells which overexpress either wild-type rab5 or rab5:Q79L, a constitutively active rab5 mutant, develop enlarged cytoplasmic vesicles that exhibit many characteristics of early endosomes including immunoreactivity for rab5 and transferrin receptor. Time-lapse video microscopy shows the enlarged endosomes arise primarily by fusion of smaller vesicles. These fusion events occur mostly by a 'bridge' fusion mechanism in which the initial opening between vesicles does not expand; instead, membrane flows slowly and continuously from the smaller to the larger endosome in the fusing pair, through a narrow, barely perceptible membranous 'bridge' between them. The unique aspect of rab5 mediated 'bridge' fusion is the persistence of a tight constriction at the site where vesicles merge and we hypothesize that this constriction results from the relatively slow disassembly of a putative docking/fusion complex. To determine the relation of rab5 to the fusion 'bridge', we used confocal fluorescence microscopy to monitor endosome fusion in cells overexpressing GFP-rab5 fusion proteins. Vesicle docking in these cells is accompanied by recruitment of the GFP-rab5 into a brightly fluorescent spot in the 'bridge' region between fusing vesicles that persists throughout the entire length of the fusion event and which often persist for minutes following endosome fusion. Other endosomal membrane markers, including FM4-64, are not concentrated in fusion 'bridges'. These results support the idea that the GFP-rab5 spots represent the localized accumulation of GFP-rab5 between fusing endosomes and not simply overlap of adjacent membranes. The idea that the GFP-rab5 spots do not represent membrane overlap is further supported by experiments using photobleaching techniques and confocal imaging which show that GFP-rab5 localized in spots between fusion couplets is resistant to diffusion while GFP-rab5 on endosomal membranes away from these spots rapidly diffuses with a rate constant of about 1.0 (+/-0.3) x10(-)(9)cm(2)/second.

Animals↗
PubMed1998

Interleukin (IL)-15 enhances antibody-dependent cellular cytotoxicity and natural killer activity in neonatal cells.

Interleukin (IL)-15 is a novel cytokine that is very similar to IL-2 in receptor specificity and biological activities. We compared the ability of IL-15 and IL-12 to enhance the cytotoxicity of neonatal (cord blood) and adult mononuclear cells (MNC) in both natural killer (NK) and antibody-dependent cellular cytotoxicity (ADCC) assays. Incubation with IL-15 (10 ng/ml) or IL-12 (1 ng/ml) for 18 h enhanced the NK activity (using K562 target cells) of both cord and adult MNC, increasing cord cell cytotoxicity threefold. Similar enhancement was seen in ADCC assays using erythrocyte targets and NK-resistant CEM cells coated with HIV gp-120 antigen. Incubation of cord cells with IL-15 or IL-12 for 1 week increased both NK and ADCC, although the combination produced less of an effect than either cytokine alone. IL-15 also increased the percentage of CD16+/CD56+ cells after 1 week incubation. This enhancement of NK and ADCC activities and the number of NK cells by IL-15 suggests it may be clinically useful in treating immunodeficient patients.

Adjuvants, Immunologic↗
PubMed1998

Intraspecific variation in the induction of female sexual receptivity in prairie voles.

Prairie voles (Microtus ochrogaster) are monogamous New World rodents which show geographic variation in social behavior. In this study, parameters of female reproduction which might be related to mating system were compared in prairie voles from eastern Kansas (KAN) versus central Illinois (ILL). KAN females showed a more rapid onset of natural estrus following exposure to a male and were more likely to respond to injections of a low dose (0.5 microg) of exogenous estradiol benzoate than ILL females. Neither mating duration nor pregnancy success after mate removal differed in KAN versus ILL females. These results suggest that ILL voles are less sensitive than KAN voles to the estrus-inducing effects of either endogenous or exogenous estrogen, supporting the hypothesis that variations in reproductive strategy occur among geographically discrete populations of prairie voles.

Animals↗
PubMed1998

Effect of interleukin (IL)-12 and IL-15 on activated natural killer (ANK) and antibody-dependent cellular cytotoxicity (ADCC) in HIV infection.

The ability of IL-12 and IL-15 to enhance natural killer (NK) activity and antibody-dependent cellular cytotoxicity (ADCC) of mononuclear cells (MNCs) from HIV+ children and their mothers was investigated. MNCs from HIV+ patients were deficient in NK and ADCC activity compared to control MNCs against several target cells. Overnight incubation with IL-15 or IL-12 augmented NK activity of MNCs from both patients and controls, and the combination of IL-12 and IL-15 resulted in the greatest enhancement. ADCC in HIV+ patients against gp120-coated CEM.NKR cells or chicken erythrocytes could also be enhanced by IL-2 or IL-15 in overnight cultures. Culturing MNCs with either IL-2 or IL-15 for 1 week increased the NK activity in patients to levels of controls treated with these cytokines. However, the response to the combination of IL-12 and IL-15 was less than that to IL-15 alone in 1-week cultures. Culturing MNCs with IL-2 and IL-15 for 1 week also increased the percentage of CD16+/CD56+ cells in both patients and controls. Thus, IL-15 can restore the deficient NK activity in patients and may be a candidate for immunomodulative therapy in HIV+ patients.

Adult↗
PubMed1998

Enhancement of antibody-dependent cellular cytotoxicity of neonatal cells by interleukin-2 (IL-2) and IL-12.

Newborn infants are more susceptible to infections due in part to deficiencies in the cytotoxic functions of their lymphocytes. We investigated the ability of interleukin-2 (IL-2) and IL-12 to enhance the cytotoxicity of neonatal (cord blood) and adult mononuclear cells (MNCs) in both natural killer (NK) cell and antibody-dependent cellular cytotoxicity (ADCC) assays. The cytotoxic activity of cord blood MNCs was less than 50% that of adult MNCs in most assays prior to exposure to cytokines. Incubation with IL-2 (100 U/ml) or IL-12 (1 ng/ml) for 18 h increased the NK cell activity (using K562 target cells) of both cord blood and adult MNCs, and the combination of IL-2 and IL-12 increased cord blood cytotoxicity threefold, making the cytotoxicity of cord blood cells equivalent to that of adult cells treated with the same cytokines. In ADCC assays with chicken erythrocyte targets, the combination of IL-2 and IL-12 increased the cytotoxicities of both cord blood and adult MNCs, with greater enhancement again seen with cord blood cells. In assays with NK cell-resistant CEM cells coated with human immunodeficiency virus (HV) gp120 antigen in the presence of hyperimmune anti-HIV immunoglobulin, ADCC of cord blood MNCs was about 50% that of adult MNCs; ADCC of cord blood MNCs increased two- to threefold with the addition of IL-2 and IL-12, whereas ADCC of adult MNCs did not increase. Incubation of cord blood cells, but not adult cells, with IL-2 or IL-12 for 1 week increased the percentage of CD16+/CD56+ cells two- to fivefold and enhanced ADCC activity. Thus, IL-2 and IL-12 greatly enhance both the NK cell and ADCC activities of neonatal MNCs and increase the number of NK cells in longer-term culture.

Adult↗
PubMed1997

14-3-3 proteins are essential for RAS/MAPK cascade signaling during pseudohyphal development in S. cerevisiae.

14-3-3 proteins are highly conserved ubiquitous proteins whose explicit functions have remained elusive. Here, we show that the S. cerevisiae 14-3-3 homologs BMH1 and BMH2 are not essential for viability or mating MAPK cascade signaling, but they are essential for pseudohyphal-development MAPK cascade signaling and other processes. Activated alleles of RAS2 and CDC42 induce pseudohyphal development and FG(TyA)-lacZ signaling in Bmh+ strains but not in ste20 (p65PAK) or bmh1 bmh2 mutant strains. Moreover, Bmh1p and Bmh2p associate with Ste20p in vivo. Three alleles of BMH1 encode proteins defective for FG(TyA)-lacZ signaling and association with Ste20p, yet these alleles complement other 14-3-3 functions. Therefore, the 14-3-3 proteins are specifically required for RAS/MAPK cascade signaling during pseudohyphal development in S. cerevisiae.

14-3-3 Proteins↗
PubMed1997

Perinatal hormone exposure alters the expression of selective affiliative preferences in prairie voles.

In the present study, perinatal administration of corticosterone and testosterone significantly influenced affiliative preferences only in females. Despite the very high levels of steroids given, no significant differences were noted among treated and untreated groups of males. Prairie voles apparently are uniquely adapted to tolerate high levels of endogenous steroids. However, females of this species may be capable of exploiting variations in corticosterone levels to regulate sexually dimorphic traits, including social behaviors, in adulthood. Perinatal responsivity to adrenal hormones could allow animals to adapt their social behaviors, including traits that have been used to characterize monogamy and/or communal breeding, to environmental demands.

Animals↗
PubMed1997

Human immunodeficiency virus (HIV) type-1 GP120-specific cell-mediated cytotoxicity (CMC) and natural killer (NK) activity in HIV-infected (HIV+) subjects: enhancement with interleukin-2(IL-2), IL-12, and IL-15.

Cell-mediated cytotoxicity (CMC), as mediated by cytophilic antibody to human immunodeficiency virus (HIV) antigens, may be an important defense in HIV-infected (HIV+) patients in response to the virus. In this study the ability of interleukin (IL)-2, IL-12, and IL-15 to enhance natural killer (NK) and gp120-specific CMC of mononuclear cells (MNCs) from HIV+ children and adults was examined. NK activity against K562 cells was deficient in HIV+ patients compared to controls and could be enhanced by IL-2, IL-12, or IL-15, with the combinations of IL-2 + IL-12 and IL-12 + IL-15 producing more cytotoxicity than individual cytokines. Gp120-specific CMC was significantly higher in patients than in controls. It could be increased by IL-2, IL-12, and IL-15 and further by combining IL-2 and IL-12. When an exogenous source of antibody in the form of hyperimmune HIV-specific immunoglobulin (HIVIG) was present, the response of control MNCs was much higher than that of patients, although gp120-specific cytotoxicity of patients' MNCs was significantly enhanced (two- to threefold) by the addition of HIVIG. This increment in cytotoxicity due to HIVIG, however, could not be further augmented by cytokines in controls or patients. Our findings suggest multiple cytokine administration to boost NK cell function, together with passive immunotherapy, might offer a new therapeutic approach to benefit HIV+ patients.

Adolescent↗
PubMed1997

Antibody-directed natural cytotoxicity results in enhanced killing of HIV gp120-coated CEMNKR cells.

Cellular cytotoxicity may be an important defense in the control of HIV progression. In the present study antibodies were attached to peripheral blood mononuclear cells (PBMC) by exposing them to polyethylene glycol and phthalate oil in the presence of HIV human hyperimmune IVIG (HIVIG). The attachment procedure is known as "franking" and the resultant cytotoxicity is termed "antibody-directed." The majority of the cells that are franked with attached HIVIG are CD16+ (Fc gamma RIII), placing them in the natural killer cell population. Franking increased the cytotoxicity of PBMC from both healthy controls and HIV-seropositive patients approximately fourfold compared to conventional antibody-dependent cellular cytotoxicity using CEM cells coated with HIV gp120 antigen as targets. Use of anti-HIV monoclonal antibodies for franking was less efficient than polyclonal HIVIG. The HIVIG-franked PBMC suppressed p24 production of in vitro HIV IIIb-infected human PBMC. The ability of HIVIG to enhance and direct cytotoxicity to HIV targets may suggest a new therapeutic approach to HIV control.

Adult↗
PubMed1997

Treatment of chronic recurrent multifocal osteomyelitis with interferon gamma.

Chronic recurrent multifocal osteomyelitis is characterized by recurrent episodes of painful swollen lesions of the bone and overlying skin with radiographic changes and an elevated sedimentation rate. It resembles infectious osteomyelitis but with negative findings on bacterial culture and no response to antibiotics. We treated a 13-year-old girl with interferon gamma for 3 months. She had 11 episodes of chronic recurrent multifocal osteomyelitis in 2 1/2 years before therapy and has had none in the 15 months since therapy, an outcome suggesting a favorable therapeutic response.

Adolescent↗
PubMed1997

Sexual differentiation in prairie voles: the effects of corticosterone and testosterone.

Prairie voles (Microtus ochrogaster) exhibit low levels of physical sexual dimorphism and have endogenous basal corticosterone levels that are 5-10 times higher than those measured in rats; prairie voles also do not show a postnatal period of adrenal hyporesponsivity. On the basis of studies in rats suggesting that adrenal hyperactivity during the perinatal period could reduce masculinization or feminize sexual behavior, we hypothesized that adrenal hormones might influence sexual differentiation in prairie voles. We also examined the hypothesis that the effects of testosterone in prairie voles might differ from those reported in other rodents. Treatments with either corticosterone or testosterone propionate (TP) were given prenatally (gestational Days 12-20), via maternal injection, or postnatally (Days 1-6), by directly injecting the pups. Additional groups of males were castrated or sham-operated on postnatal Day 1, and a subgroup of castrated males received postnatal TP. Male and female sexual behavior was observed in adulthood following gonadectomy and hormone treatments. Corticosterone treatment was associated with high levels of mounting in both sexes and did not inhibit lordosis behavior in females. Postnatal TP treatment inhibited lordosis in females but did not facilitate mounting in either sex. Males that were castrated at birth showed unexpectedly high levels of mounting in response to adult androgens. The results of this study suggest that in prairie voles corticosterone is capable of masculinizing without defeminizing sexual behavior, whereas postnatal testicular secretions are not essential for, and may actually inhibit, masculinization in this species.

Animals↗
PubMed1997

The role of neutrophils in the production of hypoxic-ischemic brain injury in the neonatal rat.

Neutrophils contribute to ischemic brain injury in adult animals. The role of neutrophils in perinatal hypoxic-ischemic (HI) brain injury is unknown. Allopurinol reduces neutrophil accumulation after tissue ischemia and is protective against HI brain injury. This study was designed to investigate how neutrophils contribute to perinatal hypoxic ischemic brain injury and how neutropenia compared with allopurinol in its neuroprotective effects. A HI insult was produced in the right cerebral hemisphere of 7-d-old rats by right common carotid artery ligation and systemic hypoxia. Half the rats were rendered neutropenic with an anti-neutrophil serum (ANS). At 15 min of recovery from hypoxia, half the neutropenic and nonneutropenic rats received allopurinol (135 mg/kg, s.c.). The protective effect of the four treatment combinations was determined on brain swelling at 42 h of recovery. Neutropenia reduced brain swelling by about 70%, p < 0.01. Allopurinol alone produced similar protection so that the relatively small number of animals studied did not permit assessment of an additive effect. Neutrophil accumulation in cerebral hemispheres was measured by myeloperoxidase (MPO) activity assay and by neutrophil counts in 6-microm sections stained by MPO and ANS immunostaining. MPO activity peaked between 4 and 8 h of recovery in both hemispheres. Hemispheric neutrophil counts peaked at the end of the HI insult and again at 18 h of recovery. Neutrophils were stained within blood vessels and did not infiltrate the injured brain before infarction had occurred. We conclude that neutrophils contribute to HI brain injury in the neonate and that neutrophil depletion before the insult is neuroprotective.

Allopurinol↗