Biomedical subjects

T A Davis

Publications and source records attributed to T A Davis.

At least 19 recordsLinked to original sources

PubMed2005

Large genomic rearrangements of both BRCA2 and BRCA1 are a feature of the inherited breast/ovarian cancer phenotype in selected families.

INTRODUCTION: A strong family history of breast and/or ovarian cancer can often be explained by small insertions, deletions, or substitutions in BRCA1 or BRCA2 and large genomic rearrangements in BRCA1. However, there is little evidence that genomic rearrangements are a major factor in BRCA2 associated breast cancer and the frequencies of rearrangements in BRCA1 in large clinic based populations are unknown. OBJECTIVE: To investigate the frequency of large genomic rearrangements in BRCA1 and BRCA2 in a large clinic based population at high risk of developing breast and/or ovarian cancer. METHODS: Multiplex ligation dependent probe amplification was used to comprehensively screen BRCA1 and/or BRCA2 in 312 index cases. RESULTS: Three novel deletions detected in BRCA2 were found exclusively in families with at least one case of male breast cancer. Novel rearrangements in BRCA1 were detected mostly in families with both breast and ovarian cancer. Families with these mutations were significantly younger at average age of cancer diagnosis. CONCLUSION: Screening for large genomic rearrangements in both BRCA1 and BRCA2 is strongly supported by this study, in particular in multiple case breast/ovarian families with a young age of onset (BRCA1) and families containing at least one case of male breast cancer (BRCA2).

Base Sequence↗

PubMed2004

Peripheral leptin administration alters hormone and metabolite levels in the young pig.

The present study was conducted to determine if peripheral leptin administration can alter GH secretion or feed intake in young pigs. Six, 6 kg female pigs were fasted overnight and randomly chosen to receive porcine recombinant leptin or saline injections in a crossover design. Three leptin dosages were tested over a 10 day period, 100, 200 or 500 microg/kg body mass (L100, L200 or L500). Leptin was administered in 0.2% bovine serum albumin as a bolus injection into the carotid artery. Blood samples were obtained from the jugular vein over a 24 h period. Leptin delayed feeding in pigs treated with L200 and L500 (P<0.05), while reducing overall intake in pigs treated with L100 (P<0.05). L200 or L500 depressed blood glucose (P<0.05). Plasma insulin levels were elevated by feeding in control animals, while insulin levels were depressed in pigs treated with L200 or L500 (P<0.05). L200 elevated plasma growth hormone (P<0.05) with three peaks apparent at 5, 8, and 13 h post injection. The ability for a single injection of leptin to produce significant changes in hormone and metabolite levels suggests that this peptide has a role in regulation of peripheral metabolism.

Animals↗

PubMed2004

Somatotropin regulation of protein metabolism in pigs.

A primary goal of exogenous somatotropin treatment is to increase lean body mass. This is accomplished, in part, by increasing the efficiency with which dietary amino acids are used for protein deposition. Somatotropin administration also improves protein balance by minimizing the loss of protein during fasting and maximizing the protein gained during meal absorption. Amino acid catabolism is decreased by somatotropin treatment, as indicated by decreases in blood urea nitrogen, urea synthesis, hepatic urea cycle enzyme activity, and amino acid oxidation. Stable isotope tracer/mass transorgan balance studies have recently demonstrated that somatotropin treatment increases protein anabolism in young, growing swine by increasing protein synthesis in the hind limb and portal-drained viscera in the fed state, with little effect on protein degradation. Detailed study of the tissue-specific responses indicates that somatotropin treatment increases protein synthesis in skeletal muscle by increasing the efficiency of the translational process, but only in the fed state. The somatotropin-induced stimulation of skeletal muscle protein synthesis involves mechanisms that enhance the binding of both mRNA and initiator methionyl-tRNA to the 40S ribosomal subunit. Somatotropin increases protein synthesis in the liver in both the fasted and fed states by increasing ribosome number, with no change in translation initiation. Thus, the protein synthetic response to somatotropin treatment is tissue-specific and dependent on nutritional state.

Animals↗

PubMed2003

Influence of Bacillus subtilis cell walls and EDTA on calcite dissolution rates and crystal surface features.

This study investigates the influence of EDTA and the Gram-positive cell walls of Bacillus subtilis on the dissolution rates and development of morphological features on the calcite [1014] surface. The calcite dissolution rates are compared at equivalent saturation indicies (SI) and relative to its dissolution behavior in distilled water (DW). Results indicate that the presence of metabolically inactive B. subtilis does not affect the dissolution rates significantly. Apparent increases in dissolution rates in the presence of the dead bacterial cells can be accounted for by a decrease of the saturation state of the solution with respect to calcite resulting from bonding of dissolved Ca2+ by functional groups on the cell walls. In contrast, the addition of EDTA to the experimental solutions results in a distinct increase in dissolution rates relative to those measured in DW and the bacterial cell suspensions. These results are partly explained by the 6.5-8 orders of magnitude greater stability of the Ca-EDTA complex relative to the Ca-B. subtilis complexes as well as its free diffusion to and direct attack of the calcite surface. Atomic force microscopy images of the [1014] surface of calcite crystals exposed to our experimental solutions reveal the development of dissolution pits with different morphologies according to the nature and concentration of the ligand. Highly anisotropic dissolution pits develop in the early stages of the dissolution reaction at low B. subtilis concentrations (0.004 mM functional group sites) and in DW. In contrast, at high functional group concentrations (4.0 mM EDTA or equivalent B. subtilis functional group sites), dissolution pits are more isotropic. These results suggest that the mechanism of calcite dissolution is modified by the presence of high concentrations of organic ligands. Since all the pits that developed on the calcite surfaces display some degree of anisotropy and dissolution rates are strongly SI dependent, the rate-limiting step is most likely a surface reaction for all systems investigated in this study. Results of this study emphasize the importance of solution chemistry and speciation in determining calcite reaction rates and give a more accurate and thermodynamically sound representation of dead bacterial cell wall-mineral interactions. In studies of natural aquatic systems, the presence of organic ligands is most often ignored in speciation calculations. This study clearly demonstrates that this oversight may lead to an overestimation of the saturation state of the solutions with respect to calcite and thermodynamic inconsistencies.

Bacillus subtilis↗

PubMed2001

Idiotype vaccination following ABMT can stimulate specific anti-idiotype immune responses in patients with B-cell lymphoma.

Vaccination with the idiotype (Id) protein derived from B-cell malignancies can produce Id-specific immune responses that correlate with improved remission duration and survival rates in patients with follicular non-Hodgkin's lymphoma (NHL). A state of minimal or no residual disease correlates strongly with the laboratory detection of a cellular or humoral immune response. High-dose cytotoxic therapy (HDCT) with autologous stem cell support (autologous bone marrow transplantation [ABMT]) can provide profound cytoreduction of B-cell NHL, but the potential immune suppression associated with myeloablative therapy may compromise a patient's ability to mount a specific immune response. To determine whether patients with NHL could mount detectable immuneresponses following ABMT, Id vaccines were administered at 2 to 12 months following myeloablative therapy to a series of patients with relapsed or resistant B-cell NHL. Two different vaccination strategies produced robust immune responses against KLH in all patients, supporting the capacity of the reconstituted immune system following HDCT to react against a strong antigen. Combining the results from both vaccination strategies, 10 of 12 patients mounted Id-specific humoral or cellular responses. Vaccinations were consistently well tolerated. Of the 12 patients, 7 have experienced prolonged remissions with a follow-up from HDCT ranging from 3 to more than 11 years. Our experience serves to document the ability of the recovering immune system to react against both self and xenotypic antigens and supports the feasibility and safety of antigen-specific vaccination following myeloablative therapy in patients with B-cell NHL.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed2001

Of flux and flooding: the advantages and problems of different isotopic methods for quantifying protein turnover in vivo : II. Methods based on the incorporation of a tracer.

The most common methods for measuring the incorporation of tracer amino acids into tissue protein are the constant tracer infusion and the flooding dose. The flooding dose is an attractive method for measuring tissue protein synthesis because of its convenience and precision. A primary assumption of the method, that the free amino acid precursor pools are equilibrated with the true precursor pool, aminoacyl-transfer RNA, has recently been validated. When short labelling periods are involved, the large dose of amino acid does not appear to alter protein synthesis. The constant tracer infusion is a satisfactory method from a theoretical point of view, but its use requires the measurement of the protein synthetic precursor pool. The best estimate of the aminoacyl-tRNA precursor pool for the constant infusion method appears to be the acid-soluble tissue pool in muscle and VLDL apolipoprotein B-100 in the liver. The experimental approach chosen for measuring tissue protein synthesis should be dictated by the question being addressed.

Amino Acids↗

PubMed2001

Differential effects of insulin on peripheral and visceral tissue protein synthesis in neonatal pigs.

We recently demonstrated in neonatal pigs that, with amino acids and glucose maintained at fasting levels, the stimulation of protein synthesis in longissimus dorsi muscle with feeding can be reproduced by a physiological rise in insulin alone. In the current report, we determine whether the response of protein synthesis to insulin in the neonatal pig is 1) present in muscles of different fiber types, 2) proportional in myofibrillar and sarcoplasmic proteins, 3) associated with increased translational efficiency and ribosome number, and 4) present in other peripheral tissues and in viscera. Hyperinsulinemic-euglycemic-amino acid clamps were performed in 7- and 26-day-old pigs infused with 0, 30, 100, or 1,000 ng. kg(-0.66). min(-1) of insulin to reproduce insulin levels present in fasted, fed, refed, and supraphysiological conditions, respectively. Tissue protein synthesis was measured using a flooding dose of L-[4-(3)H]phenylalanine. Insulin increased protein synthesis in gastrocnemius muscle and, to a lesser degree, masseter muscle. The degree of stimulation of protein synthesis by insulin was similar in myofibrillar and sarcoplasmic proteins. Insulin increased translational efficiency but had no effect on ribosome number in muscle. All of these insulin-induced changes in muscle protein synthesis decreased with age. Insulin also stimulated protein synthesis in cardiac muscle and skin but not in liver, intestine, spleen, pancreas, or kidney. The results support the hypothesis that insulin mediates the feeding-induced stimulation of myofibrillar and sarcoplasmic protein synthesis in muscles of different fiber types in the neonate by increasing the efficiency of translation. However, insulin does not appear to be involved in the feeding-induced stimulation of protein synthesis in visceral tissues. Thus different mechanisms regulate the growth of peripheral and visceral tissues in the neonate.

Amino Acids↗

PubMed2001

Developmental changes in the feeding-induced activation of the insulin-signaling pathway in neonatal pigs.

In neonatal animals, feeding stimulates skeletal muscle protein synthesis, a response that declines with development. Both the magnitude of the feeding response and its developmental decline can be reproduced by insulin infusion, suggesting that an altered responsiveness to insulin is a primary determinant of the developmental decline in the stimulation of protein synthesis by feeding. In this study, 7- and 26-day-old pigs were either fasted overnight or fed porcine milk after an overnight fast. We examined the abundance and degree of tyrosine phosphorylation of the insulin receptor (IR), insulin receptor substrate-1 (IRS-1), and IRS-2 in skeletal muscle and, for comparison, liver. We also evaluated the association of IRS-1 and IRS-2 with phosphatidylinositol 3-kinase (PI 3-kinase). The abundance of IR protein in muscle was twofold higher at 7 than at 26 days, but IRS-1 and IRS-2 abundances were similar in muscle of 7- and 26-day-old pigs. The feeding-induced phosphorylations were greater at 7 than at 26 days of age for IR (28- vs. 13-fold), IRS-1 (14- vs. 8-fold), and IRS-2 (21- vs. 12-fold) in muscle. The associations of IRS-1 and IRS-2 with PI 3-kinase were also increased by refeeding to a greater extent at 7 than at 26 days (9- vs. 5-fold and 6- vs. 4-fold, respectively). In liver, the abundance of IR, IRS-1, and IRS-2 was similar at 7 and 26 days of age. Feeding increased the activation of IR, IRS-1, IRS-2, and PI 3-kinase in liver only twofold, and these responses were unaffected by age. Thus our findings demonstrate that the feeding-induced activation of IR, IRS-1, IRS-2, and PI 3-kinase in skeletal muscle decreases with development. Further study is needed to ascertain whether the developmental decline in the feeding-induced activation of early insulin-signaling components contributes to the developmental decline in translation initiation in skeletal muscle.

Animals↗

PubMed2000

Protein nutrition of the neonate.

The period of growth and development between birth and weaning is crucial for the long-term well-being of the organism. Protein deposition is very rapid, is achieved with a high nutritional efficiency, and is accompanied by marked differences in the growth rates of individual tissues and a series of maturational processes. These important aspects of development occur while the neonate is consuming a single and highly-specific food source, milk. Surprisingly, although there is a clear relationship between the nutrient density of milk and the growth rate of its recipient, this relationship does not apply to the overall amino acid composition of mixed milk proteins. Some amino acids, notably glycine and arginine, are supplied in milk in quantities that are much less than the needs of the neonate. The milk-fed neonate is therefore capable of carrying out a tightly-regulated transfer of N from amino acids in excess to those that are deficient. The rapid growth of the neonate is supported by a high rate of tissue protein synthesis. This process appears to be activated by the consumption of the first meals of colostrum. Recent research has identified that skeletal muscle and the brain are specifically responsive to an unidentified factor in colostrum. Following the initial anabolic response the rate of protein synthesis in some tissues, notably muscle, falls from birth to weaning. This decrease reflects a progressively smaller anabolic response to nutrient intake, which not only involves an overall fall in the capacity for protein synthesis, but also in responses to insulin and amino acids. The study of growth and protein metabolism, and their regulation in the neonate is not only important for pediatrics, but may provide important pointers to more general aspects of regulation that could be applied to the nutrition of the mature animal.

Amino Acids↗

PubMed2000

Somatotropin increases protein balance by lowering body protein degradation in fed, growing pigs.

Somatotropin (ST) administration enhances protein deposition in well-nourished, growing animals. To determine whether the anabolic effect is due to an increase in protein synthesis or a decrease in proteolysis, pair-fed, weight-matched ( approximately 20 kg) growing swine were treated with porcine ST (150 microg. kg(-1). day(-1), n = 6) or diluent (n = 6) for 7 days. Whole body leucine appearance (R(a)), nonoxidative leucine disposal (NOLD), urea production, and leucine oxidation, as well as tissue protein synthesis (K(s)), were determined in the fed steady state using primed continuous infusions of [(13)C]leucine, [(13)C]bicarbonate, and [(15)N(2)]urea. ST treatment increased the efficiency with which the diet was used for growth. ST treatment also increased plasma insulin-like growth factor I (+100%) and insulin (+125%) concentrations and decreased plasma urea nitrogen concentrations (-53%). ST-treated pigs had lower leucine R(a) (-33%), leucine oxidation (-63%), and urea production (-70%). However, ST treatment altered neither NOLD nor K(s) in the longissimus dorsi, semitendinosus, or gastrocnemius muscles, liver, or jejunum. The results suggest that in the fed state, ST treatment of growing swine increases protein deposition primarily through a suppression of protein degradation and amino acid catabolism rather than a stimulation of protein synthesis.

Animals↗

PubMed2000

Somatotropin increases protein balance independent of insulin's effects on protein metabolism in growing pigs.

Somatotropin (ST) administration enhances protein deposition and elicits profound metabolic responses, including hyperinsulinemia. To determine whether the anabolic effect of ST is due to hyperinsulinemia, pair-fed weight-matched growing swine were treated with porcine ST (150 microg x kg body wt(-1) x day(-1)) or diluent for 7 days (n = 6/group, approximately 20 kg). Then pancreatic glucose-amino acid clamps were performed after an overnight fast. The objective was to reproduce the insulin levels of 1) fasted control and ST pigs (basal insulin, 5 microU/ml), 2) fed control pigs (low insulin, 20 microU/ml), and 3) fed ST pigs (high insulin, 50 microU/ml). Amino acid and glucose disposal rates were determined from the infusion rates necessary to maintain preclamp blood levels of these substrates. Whole body nonoxidative leucine disposal (NOLD), leucine appearance (R(a)), and leucine oxidation were determined with primed, continuous infusions of [(13)C]leucine and [(14)C]bicarbonate. ST treatment was associated with higher NOLD and protein balance and lower leucine oxidation and amino acid and glucose disposals. Insulin lowered R(a) and increased leucine oxidation, protein balance, and amino acid and glucose disposals. These effects of insulin were suppressed by ST treatment; however, the protein balance remained higher in ST pigs. The results show that ST treatment inhibits insulin's effects on protein metabolism and indicate that the stimulation of protein deposition by ST treatment is not mediated by insulin. Comparison of the protein metabolic responses to ST treatment during the basal fasting period with those in the fully fed state from a previous study suggests that the mechanism by which ST treatment enhances protein deposition is influenced by feeding status.

Aging↗

PubMed2000

Feeding stimulates protein synthesis in muscle and liver of neonatal pigs through an mTOR-dependent process.

Protein synthesis is repressed in both skeletal muscle and liver after a short-term fast and is rapidly stimulated in response to feeding. Previous studies in rats and pigs have shown that the feeding-induced stimulation of protein synthesis is associated with activation of the 70-kDa ribosomal protein S6 kinase (S6K1) as well as enhanced binding of eukaryotic initiation factor eIF4E to eIF4G to form the active eIF4F complex. In cells in culture, hormones and nutrients regulate both of these events through a protein kinase termed the mammalian target of rapamycin (mTOR). In the present study, the involvement of mTOR in the feeding-induced stimulation of protein synthesis in skeletal muscle and liver was examined. Pigs at 7 days of age were fasted for 18 h, and then one-half of the animals were fed. In addition, one-half of the animals in each group were administered rapamycin (0.75 mg/kg) 2 h before feeding. The results reveal that treating 18-h fasted pigs with rapamycin, a specific inhibitor of mTOR, before feeding prevented the activation of S6K1 and the changes in eIF4F complex formation observed in skeletal muscle and liver after feeding. Rapamycin also ablated the feeding-induced stimulation of protein synthesis in liver. In contrast, in skeletal muscle, rapamycin attenuated, but did not prevent, the stimulation of protein synthesis in response to feeding. The results suggest that feeding stimulates hepatic protein synthesis through an mTOR-dependent process involving enhanced eIF4F complex formation and activation of S6K1. However, in skeletal muscle, these two processes may account for only part of the stimulation of protein synthesis, and thus additional steps may be involved in the response.

Animals↗

PubMed2000

Developmental changes in the feeding-induced stimulation of translation initiation in muscle of neonatal pigs.

The rapid gain in skeletal muscle mass in the neonate is associated with a marked elevation in skeletal muscle protein synthesis in response to feeding. The feeding-induced response decreases with development. To determine whether the response to feeding is regulated at the level of translation initiation, the expression, phosphorylation, and function of a number of eukaryotic initiation factors (eIF) were examined. Pigs at 7 and 26 days of age were either fasted overnight or fed porcine milk after an overnight fast. In muscle of 7-day-old pigs, the hyperphosphorylated form of the eIF4E repressor protein, 4E-binding protein 1 (4E-BP1), was undetectable in the fasting state but rose to 60% of total 4E-BP1 after feeding; eIF4E phosphorylation was unaffected by feeding status. The amount of eIF4E in the inactive 4E-BP1. eIF4E complex was reduced by 80%, and the amount of eIF4E in the active eIF4E. eIF4G complex was increased 14-fold in muscle of 7-day-old pigs after feeding. The amount of 70-kDa ribosomal protein S6 (p70(S6)) kinase in the hyperphosphorylated form rose 2.5-fold in muscle of 7-day-old pigs after feeding. Each of these feeding-induced responses was blunted in muscle of 26-day-old pigs. eIF2B activity in muscle was unaffected by feeding status but decreased with development. Feeding produced similar changes in eIF characteristics in liver and muscle; however, the developmental changes in liver were not as apparent as in skeletal muscle. Thus the results demonstrate that the developmental change in the acute stimulation of skeletal muscle protein synthesis by feeding is regulated by the availability of eIF4E for 48S ribosomal complex formation. The results further suggest that the overall developmental decline in skeletal muscle protein synthesis involves regulation by eIF2B.

Animals↗

PubMed2000

Regulation of myofibrillar protein turnover during maturation in normal and undernourished rat pups.

The study tested the hypothesis that a higher rate of myofibrillar than sarcoplasmic protein synthesis is responsible for the rapid postdifferentiation accumulation of myofibrils and that an inadequate nutrient intake will compromise primarily myofibrillar protein synthesis. Myofibrillar (total and individual) and sarcoplasmic protein synthesis, accretion, and degradation rates were measured in vivo in well-nourished (C) rat pups at 6, 15, and 28 days of age and compared at 6 and 15 days of age with pups undernourished (UN) from birth. In 6-day-old C pups, a higher myofibrillar than sarcoplasmic protein synthesis rate accounted for the greater deposition of myofibrillar than sarcoplasmic proteins. The fractional synthesis rates of both protein compartments decreased with age, but to a greater degree for myofibrillar proteins (-54 vs. -42%). These decreases in synthesis rates were partially offset by reductions in degradation rates, and from 15 days, myofibrillar and sarcoplasmic proteins were deposited in constant proportion to one another. Undernutrition reduced both myofibrillar and sarcoplasmic protein synthesis rates, and the effect was greater at 6 (-25%) than 15 days (-15%). Decreases in their respective degradation rates minimized the effect of undernutrition on sarcoplasmic protein accretion from 4 to 8 days and on myofibrillar proteins from 13 to 17 days. Although these adaptations in protein turnover reduced overall growth of muscle mass, they mitigated the effects of undernutrition on the normal maturational changes in myofibrillar protein concentration.

Actins↗

PubMed2000

Rituximab anti-CD20 monoclonal antibody therapy in non-Hodgkin's lymphoma: safety and efficacy of re-treatment.

PURPOSE: This phase II trial investigated the safety and efficacy of re-treatment with rituximab, a chimeric anti-CD20 monoclonal antibody, in patients with low-grade or follicular non-Hodgkin's lymphoma who relapsed after a response to rituximab therapy. PATIENTS AND METHODS: Fifty-eight patients were enrolled onto this study, and two were re-treated within the study. Patients received an intravenous infusion of 375 mg/m(2) of rituximab weekly for 4 weeks. All patients had at least two prior therapies and had received at least one prior course of rituximab, with a median interval of 14.5 months between rituximab courses. RESULTS: Most adverse experiences (AEs) were transient grade 1 or 2 events occurring during the treatment period. Clinically significant myelosuppression was not observed; hematologic toxicity was generally mild and reversible. No patient developed human antichimeric antibodies after treatment. The type, frequency, and severity of AEs in this study were not apparently different from those reported in the phase III trial of rituximab. The overall response rate in 57 assessable patients was 40% (11% complete response and 30% partial responses). Median time to progression (TTP) in responders and median duration of response (DR) have not been reached, but Kaplan-Meier estimated medians are 17.8 months (range, 5.4+ to 26.6 months) and 16.3 months (range, 3.7+ to 25.1 months), respectively. These estimated medians are longer than the medians achieved in the patients' prior course of rituximab (TTP and DR of 12.4 and 9.8 months, respectively, P: >.1) and in a previously reported phase III trial (TTP in responders and DR of 13.2 and 11.6 months, respectively). Responses are ongoing in seven of 23 responders. CONCLUSION: In this re-treatment population, safety and efficacy were not apparently different from those after initial rituximab exposure.

Adult↗

PubMed2000

Nonnutritive factors in colostrum enhance myofibrillar protein synthesis in the newborn Pig.

Colostrum is a complex source of nutrients, immune factors, and bioactive substances consumed by newborn mammals. In previous work, we observed that protein synthesis in the skeletal muscle of newborn piglets is enhanced when they are fed colostrum rather than a nutrient-matched formula devoid of growth factors. To elucidate the mechanisms responsible for this response, we contrasted the fractional rates of sarcoplasmic and myofibrillar protein synthesis of newborn piglets that received only water with those fed for 24 h with colostrum, a nutrient-matched formula, or mature sow's milk. Compared with water, feeding resulted in a 2.5- to 3-fold increase in total skeletal muscle protein synthesis, and this increase was 28% greater in the colostrum-fed than either the formula- or mature milk-fed piglets. Feeding also stimulated muscle ribosome and total polyadenylated RNA accretion. Ribosomal translational efficiency, however, was similar across all fed groups. The greater stimulation of protein synthesis in colostrum-fed pigs was restricted entirely to the myofibrillar protein compartment and was associated with higher ribosome and myosin heavy chain mRNA abundance. Taken together, these data suggest that nonnutritive factors in colostrum enhance ribosomal accretion and muscle-specific gene transcription that, in turn, stimulate specifically the synthesis of myofibrillar proteins in the skeletal musculature of the newborn.

Animals↗

PubMed2000

Combination immunotherapy of relapsed or refractory low-grade or follicular non-Hodgkin's lymphoma with rituximab and interferon-alpha-2a.

Rituximab and IFN have each demonstrated single-agent activity in patients with low-grade non-Hodgkin's lymphoma (NHL). A single-arm, multicenter, Phase II trial was conducted to assess the safety and efficacy of combination therapy with rituximab and IFN-alpha-2a in 38 patients with relapsed or refractory, low-grade or follicular, B-cell NHL. IFN-alpha-2a [2.5 or 5 million units (MIU)] was administered s.c., three times weekly for 12 weeks. Starting on the fifth week of treatment, rituximab was administered by i.v. infusion (375 mg/m2) weekly for 4 doses. All 38 patients received four complete infusions of rituximab and were evaluable for efficacy, although 11 patients (29%) did not-receive all 36 injections of IFN. The mean number of IFN-alpha-2a injections was 31 doses; the mean total units received were 141 MIU (maximum, 180 MIU). The study treatment was reasonably well tolerated with no unexpected toxicities stemming from the combination therapy. No grade 4 events were reported. Frequent adverse events during the treatment period included asthenia (35 of 38 patients), chills (31 of 38), fever (30 of 38), headache (28 of 38), nausea (23 of 38), and myalgia (22 of 38). The overall response rate was 45% (17 of 38 patients); 11% had a complete response, and 34% had a partial response. The Kaplan-Meier estimates for the median response duration and the median time to progression in responders are 22.3 and 25.2 months, respectively. Further follow-up is needed to determine whether this treatment combination leads to a significantly longer time to progression than single-agent treatment with rituximab.

Adult↗

PubMed1999

Ex vivo expansion of autologous bone marrow CD34(+) cells with porcine microvascular endothelial cells results in a graft capable of rescuing lethally irradiated baboons.

Hematopoietic stem cell (HSC) self-renewal in vitro has been reported to result in a diminished proliferative capacity or acquisition of a homing defect that might compromise marrow repopulation. Our group has demonstrated that human HSC expanded ex vivo in the presence of porcine microvascular endothelial cells (PMVEC) retain the capacity to competitively repopulate human bone fragments implanted in severe combined immunodeficiency (SCID) mice. To further test the marrow repopulating capacity of expanded stem cells, our laboratory has established a myeloablative, fractionated total body irradiation conditioning protocol for autologous marrow transplantation in baboons. A control animal, which received no transplant, as well as two animals, which received a suboptimal number of marrow mononuclear cells, died 37, 43, and 59 days postirradiation, respectively. Immunomagnetically selected CD34(+) marrow cells from two baboons were placed in PMVEC coculture with exogenous human cytokines. After 10 days of expansion, the grafts represented a 14-fold to 22-fold increase in cell number, a 4-fold to 5-fold expansion of CD34(+) cells, a 3-fold to 4-fold increase of colony-forming unit-granulocyte-macrophage (CFU-GM), and a 12-fold to 17-fold increase of cobblestone area-forming cells (CAFC) over input. Both baboons became transfusion independent by day 23 posttransplant and achieved absolute neutrophil count (ANC) >500/microL by day 25 +/- 1 and platelets >20,000/microL by day 29 +/- 2. This hematopoietic recovery was delayed in comparison to two animals that received either a graft consisting of freshly isolated, unexpanded CD34(+) cells or 175 x 10(6)/kg unfractionated marrow mononuclear cells. Analysis of the proliferative status of cells in PMVEC expansion cultures demonstrated that by 10 days, 99.8% of CD34(+) cells present in the cultures had undergone cycling, and that the population of cells expressing a CD34(+) CD38(-) phenotype in the cultures was also the result of active cell division. These data indicate that isolated bone marrow CD34(+) cells may undergo cell division during ex vivo expansion in the presence of endothelial cells to provide a graft capable of rescuing a myeloablated autologous host.

Animals↗