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Biomedical subjects

D A Williams

Publications and source records attributed to D A Williams.

At least 127 records · Page 7Linked to original sources
PubMed1998

Intracellular pH of the mouse preimplantation embryo: amino acids act as buffers of intracellular pH.

The inclusion of specific amino acids in conventional culture media has been shown to enhance mammalian embryo development in vitro. Amino acids have been shown to confer their benefits to the preimplantation embryo in a number of different ways. However, their ability to buffer intracellular pH (pHi) has not been investigated. Thus, the aim of this study was to determine if amino acids regulate pHi in the mouse preimplantation embryo. pHi was determined using carboxy-seminaphthorhodafluor-1 (SNARF-1) and confocal microscopy. Incubation with 5,5-dimethyl-2,4-oxazol-idinedione (DMO), a non-metabolizable weak acid, resulted in a significant intracellular acidification in the zygote, 2-, 4- and 8-16-cell embryo. However, in the presence of groups of amino acids, the degree of acidification due to DMO was markedly reduced in the mouse embryo up to the 4-cell stage. Specifically, non-essential amino acids and glutamine had the greatest capacity to buffer pHi in the early embryo. The ability of amino acids to buffer pHi was not apparent from the 8-16-cell stage onwards. In contrast to the precompacted embryo, the morula did not undergo a significant decrease in pHi until exposed to DMO concentrations > or = 10 mM in the absence of amino acids. This may be due to the generation of a permeability seal during compaction, thus enabling the morula to regulate its own pHi. This regulatory ability could either be reversed by causing the morula to decompact, or created by inducing premature compaction in the 8-16-cell embryo. Data presented in this study indicate that amino acids act as buffers of pHi in the early embryo and play a key role in regulating cell physiology. Further evidence for this was provided by the result that only those embryos cultured in 30 mM DMO in the presence of non-essential amino acids and 1 mM glutamine did not block at the 2-cell stage, but grew on to develop into expanded blastocysts.

Amino Acids↗
PubMed1998

High-efficiency gene transfer into normal and adenosine deaminase-deficient T lymphocytes is mediated by transduction on recombinant fibronectin fragments.

Primary human T lymphocytes are powerful targets for genetic modification, although the use of these targets in human gene therapy protocols has been hampered by low levels of transduction. We have shown previously that significant increases in the transduction of hematopoietic stem and progenitor cells with retroviral vectors can be obtained by the colocalization of the retrovirus and target cells on specific fibronectin (FN) adhesion domains (H. Hanenberg, X. L. Xiao, D. Dilloo, K. Hashino, I. Kato, and D. A. Williams, Nat. Med. 2:876-882, 1996). We studied the transfer of genes into primary T lymphocytes by using FN-assisted retroviral gene transfer. Activated T lymphocytes were infected for three consecutive days on the recombinant FN fragment CH-296 with a retroviral vector encoding the murine B7-1 protein. Transduced lymphocytes were analyzed for murine B7-1 expression, and it was found that under optimal conditions, 80 to 89% of the CD3+ lymphocytes were transduced. Gene transfer was predominantly augmented by the interaction between VLA-4 on the T lymphocytes and the FN adhesion site CS-1. Adenosine deaminase (ADA)-deficient primary T lymphocytes transduced on CH-296 with a retrovirus encoding murine ADA (mADA) exhibited levels of mADA activity severalfold higher than the levels of the endogenous human ADA protein observed in normal human T lymphocytes. Strikingly, the long-term expression of the transgene was dependent on the activation status of the lymphocytes. This approach will have important applications in human gene therapy protocols targeting primary T lymphocytes.

Adenosine Deaminase↗
PubMed1998

Contractile function and low-intensity exercise effects of old dystrophic (mdx) mice.

Old mdx mice display a severe myopathy almost identical to Duchenne's muscular dystrophy. This study examined the contractile properties of old mdx muscles and investigated any effects of low-intensity exercise. Isometric contractile properties of the extensor digitorum longus (EDL) and soleus muscles were tested in adult (8-10 mo) and old (24 mo, split into sedentary and exercised groups) mdx mice. The EDL and soleus from old mdx mice exhibited decreased absolute twitch and tetanic forces, and the soleus exhibited a > 50% decrease in relative forces (13.4 +/- 0.4 vs. 6.0 +/- 0.9 N/cm2) compared with adult mice. Old mdx muscles also showed longer contraction times and a higher percentage of type I fibers. Normal and mdx mice completed 10 wk of swimming, but mdx mice spent significantly less time swimming than normal animals (7.8 +/- 0.4 vs. 15.8 +/- 1.1 min, respectively). However, despite their severe dystrophy, mdx muscles responded positively to the low-intensity exercise. Relative tetanic tensions were increased (approximately 25% and approximately 45% for the EDL and soleus, respectively) after the swimming, although absolute forces were unaffected. Thus these results indicate that, even with a dystrophin-deficient myopathy, mdx muscles can still respond to low-intensity exercise. This study shows that the contractile function of muscles of old mdx mice displays many similarities to that of human dystrophic patients and provides further evidence that the use of non-weight-bearing, low-intensity exercises, such as swimming, has no detrimental effect on dystrophic muscle and could be a useful therapeutic aid for sufferers of muscular dystrophy.

Aging↗
PubMed1998

Enzyme-linked immunosorbent assay for canine alpha 1-protease inhibitor.

OBJECTIVE: To develop and validate an ELISA for quantifying alpha 1-protease inhibitor (alpha 1-PI) in serum and fecal extracts. PROCEDURE: Affinity-purified rabbit origin canine alpha 1-PI antibodies were biotinylated and, after addition of streptavidin-horseradish peroxidase, were used as the labeled complex in a noncompetitive immunoassay. The alpha 1-PI standards were made from purified serum canine alpha 1-PI diluted in phosphate-buffered saline solution containing 5% newborn calf serum and 0.01% thimerosal. This assay was validated by determining linearity, recovery of added alpha 1-PI, detection limit, and intra- and interassay precision. Control range for serum and fecal alpha 1-PI concentration was determined for samples from 25 healthy pet dogs. RESULTS: The standard curve was linear between 5 and 50 ng/ml. Curves plotted after serial dilution of serum also were linear and ran parallel to the standard curve. Between- and within-assay coefficients of variation were 9.1 and 8.7%, respectively. The accuracy of the assay was tested by measuring the recovery of alpha 1-PI added to serum and fecal extracts and ranged from 93 to 111%. The reference range of fecal alpha 1-PI concentration was 0.023 to 5.67 (mean +/- SD, 2.0 +/- 1.82) micrograms/g and of serum alpha 1-PI was 0.901 to 1.96 (1.42 +/- 0.32) g/L. CONCLUSIONS: This ELISA had high precision, accuracy, and reproducibility for quantification of canine alpha 1-PI concentration in serum and fecal extracts. CLINICAL RELEVANCE: Specific ELISA for alpha 1-PI may be a useful test for the diagnosis of protein-losing enteropathy in dogs, and as such, will facilitate further characterization and better understanding of this canine disorder.

Animals↗
PubMed1998

Technetium-99m DTPA aerosol contamination in lung ventilation studies.

UNLABELLED: Contamination of working areas by 99mTc DTPA aerosol is of concern to nuclear medicine technologists. This study sought to determine the extent of 99mTc DTPA contamination to technologists, and to localize sources of aerosol leakage so that methods could be identified that would minimize contamination. METHODS: Fifty to eighty millicuries 99mTc DTPA, diluted to a volume of 4-5 ml with normal saline, were injected into the nebulizing chamber of two commercially available inhalation aerosol systems. The patient's nostrils were clamped and a damp washcloth was wrapped around the patient's mouth. An alcohol swab was placed in the exit port of the exhaust filter in each delivery system, and the technologist involved wore a face mask during the inhalation phase. The patient breathed DTPA-labeled aerosol by mouth until the counting rate in the lungs was four times greater than the counting rate from the pulmonary perfusion phase. Connecting joints of the delivery system were then wipe tested. Last, a Geiger-Mueller detector (pancake probe) was used to survey all device components. Readings above 0.05 mR/hr were considered contaminated. RESULTS: The patient was the greatest source of leakage as determined by the damp washcloth, followed by the joints of the tubes of the delivery system and, finally, the system's exhaust filter. Contamination readings from face masks worn by technical personnel during the lung ventilation studies were slightly greater than 0.05 mR/hr. CONCLUSION: The findings support trace levels of contamination to both the technologist and room while performing 99mTc DTPA aerosol ventilation studies. Comparative data using the two delivery systems revealed little difference in sources of leakage and little variation in contamination measurements.

Aerosols↗
PubMed1998

Time course of gastrointestinal tract permeability to chromium 51-labeled ethylenediaminetetraacetate in healthy dogs.

OBJECTIVES: To establish values for gastrointestinal tract permeation by chromium 51-labeled ethylenediaminetetraacetate (51Cr-labeled EDTA) in healthy adult dogs, and to evaluate the time course for 51Cr-labeled EDTA absorption over a 24-hour period after its administration, in an effort to define a shorter, more practical collection method. ANIMALS: 6 healthy adult mixed-breed dogs. PROCEDURE: After an 18-hour nonfeeding period, each dog was given a solution containing 50 microCi of 51Cr-labeled EDTA in deionized water (10 ml/kg of body weight) by stomach tube. Complete urine collection was done at 2, 4, 6, and 24 hours after 51Cr-labeled EDTA administration. Five-milliliter samples of urine were counted for 15 minutes in a gamma counter, and radioactivity in urine was expressed as a percentage of the orally administered dose. RESULTS: Median (range) 24-hour urinary recovery of 51Cr-labeled EDTA after 24 hours was 15.1 (12.7 to 20.3)%. Urine collected at 2, 4, and 6 hours contained 1.0 (0.2 to 3.5)%, 6.5 (2.2 to 8.7)%, and 10.0 (8.1 to 11.7)% of the administered 51Cr-labeled EDTA, respectively. Urine passed during the first 6 hours contained, on average, 67 (54 to 77)% of the total 24-hour urine recovery. CONCLUSIONS: 6-hour urinary recovery of 51Cr-EDTA provides a potential alternative to 24-hour recovery. This shorter collection period may more specifically reflect small intestinal permeability.

Animals↗
PubMed1998

A 60-year-old woman with weakness, fatigue, and acute respiratory failure: case report and discussion of the differential diagnosis.

A 60-year-old woman with chronic progressive fatigue, diurnal somnolence, proximal muscle weakness, and dyspnea developed acute respiratory failure when given supplemental oxygen. Hypoventilation secondary to neuromuscular dysfunction was suspected by the critical care specialist. Neurologic consultation and supportive laboratory evaluations led to the diagnosis of acid maltase deficiency, which was confirmed by muscle biopsy. The discussion includes a literature review that describes the pathophysiology and treatment of this rare muscle enzyme deficiency disorder. Acid maltase deficiency should be suspected in any adult presenting with hypoxemia, fatigue, and acute respiratory failure.

Acute Disease↗
PubMed1997

Optimization of fibronectin-assisted retroviral gene transfer into human CD34+ hematopoietic cells.

Efficient retroviral gene transfer into hematopoietic stem and progenitor cells can be achieved by co-localizing retrovirus and target cells on specific adhesion domains of recombinant fibronectin (FN) fragments. In this paper, we further optimize this technology for human CD34+ cells. Investigating the role of cytokine prestimulation in retrovirus-mediated gene transfer on plates coated with the recombinant FN CH-296 revealed that prestimulation of granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood (PB) CD34+ cells was essential to achieve efficient gene transfer into clonogenic cells. The highest gene transfer occurred by prestimulating PB CD34+ cells for 40 hr with a combination of stem cell factor (SCF), G-CSF, and megakaryocyte growth and development factor (MGDF) prior to retroviral infection on CH-296. Surprisingly, a prolonged simultaneous exposure of primary CD34+ PB cells to retrovirus and cytokines in the presence of CH-296 lowered the gene transfer efficiency. Gene transfer into cytokine prestimulated CD34+ bone marrow (BM) cells was not influenced by increasing the coating concentrations of a recombinant FN fragment, CH-296, nor was it adversely influenced by increasing the number of CD34+ target cells, suggesting that the amount of retroviral particles present in the supernatant was not a limiting factor for transduction of CD34+ BM cells on CH-296-coated plates. The polycation Polybrene was not required for efficient transduction of hematopoietic cells in the presence of CH-296. Furthermore, we demonstrated that repeated exposure of CH-296 to retrovirus containing supernatant, called preloading, can be employed to concentrate the amount of retroviral particles bound to CH-296. These findings establish a simple and short clinically applicable transduction protocol that targets up to 68% of BM or G-CSF-mobilized PB CD34+ cells and is capable of genetically modifying up to 17% of CD34+CD38-/dim PB cells.

ADP-ribosyl Cyclase↗
PubMed1997

Overexpression of human stem cell factor impairs melanocyte, mast cell, and thymocyte development: a role for receptor tyrosine kinase-mediated mitogen activated protein kinase activation in cell differentiation.

Stem cell factor (SCF) is synthesized as both soluble (S) and membrane-associated (MA) proteins. Indirect insight into the function of MA and S isoforms of SCF has come from studies performed in Steel (Sl) mutant mice. However, the physiologic role(s) of these two isoforms remain unknown. In an attempt to better understand the in vivo role of c-kit/SCF interactions on various cell lineages, transgenic mice were generated that overexpress MA isoform of human SCF (hSCF). In murine cells, hSCF behaves as an antagonist to normal SCF function, due to interference with the interaction between endogenous murine SCF and its receptor, c-kit, encoded by the dominant white spotting (W) gene. Mice expressing the hSCF transgene display a variety of phenotypic abnormalities, which are accentuated when combined with W alleles. Here we show that mice homozygous for the hSCF transgene demonstrate a coat color deficiency seen in some mice homozygous for mild W alleles. Specifically, homozygous hSCF transgenic mice (hSCF220) display a pronounced forehead blaze, with additional white spots over the cervical region, as well as a very large belly spot. Doubly heterozygous animals that carry both a mutated W allele and the hSCF transgene also display an unusual pigment defect and a dramatic reduction in the number of dermal mast cells. Furthermore, overexpression of MA hSCF in the thymus results in abnormal thymocyte differentiation and proliferation, which is associated with reduced mitogen activated protein (MAP) kinase activation. Thus, MAP kinase activation by a receptor tyrosine kinase, such as c-kit, may be critical for the differentiation of thymocytes in vivo.

Animals↗
PubMed1997

Chymase cleavage of stem cell factor yields a bioactive, soluble product.

Stem cell factor (SCF) is produced by stromal cells as a membrane-bound molecule, which may be proteolytically cleaved at a site close to the membrane to produce a soluble bioactive form. The proteases producing this cleavage are unknown. In this study, we demonstrate that human mast cell chymase, a chymotrypsin-like protease, cleaves SCF at a novel site. Cleavage is at the peptide bond between Phe-158 and Met-159, which are encoded by exon 6 of the SCF gene. This cleavage results in a soluble bioactive product that is 7 amino acids shorter at the C terminus than previously identified soluble SCF. This research shows the identification of a physiologically relevant enzyme that specifically cleaves SCF. Because mast cells express the KIT protein, the receptor for SCF, and respond to SCF by proliferation and degranulation, this observation identifies a possible feedback loop in which chymase released from mast cell secretory granules may solubilize SCF bound to the membrane of surrounding stromal cells. The liberated soluble SCF may in turn stimulate mast cell proliferation and differentiated functions; this loop could contribute to abnormal accumulations of mast cells in the skin and hyperpigmentation at sites of chronic cutaneous inflammation.

Binding Sites↗
PubMed1997

High feline trypsin-like immunoreactivity in a cat with pancreatitis and hepatic lipidosis.

A 1.5-year-old domestic shorthair cat was examined because of vomiting and icterus. Clinicopathologic abnormalities included high alanine transaminase, alkaline phosphatase, and gamma-glutamyltransferase activities and high total bilirubin concentration. During abdominal ultrasonography, the left limb and body of the pancreas appeared hypoechoic, and a small quantity of peritoneal effusion was seen. The liver was diffusely hyperechoic, with echogenicity similar to that of the spleen, indicating hepatic lipidosis. Feline trypsin-like immunoreactivity was high, suggesting that the cat also had pancreatitis. The cat was treated with crystalloid fluids and was fed a protein-restricted diet via a percutaneous endoscopically placed gastrostomy tube. The cat's condition continued to deteriorate despite medical treatment, and it was euthanatized. Necropsy confirmed the clinical suspicion of acute pancreatitis and hepatic lipidosis. This case suggests that measurement of trypsin-like immunoreactivity may be useful in cats suspected of having pancreatitis.

Alanine Transaminase↗
PubMed1997

Reversal of 1,3-bis(2-chloroethyl)-1-nitrosourea-induced severe immunodeficiency by transduction of murine long-lived hemopoietic progenitor cells using O6-methylguanine DNA methyltransferase complementary DNA.

Bone marrow toxicity is a dose-limiting side effect of chloroethylnitrosourea (CNU) chemotherapeutic alkylating agents. A major determinant of CNU cytotoxicity is the methylation of guanine at the O6-position and the subsequent formation of interstrand DNA cross-links. O6-Methylguanine DNA methyltransferase (MGMT) removes alkyl groups from the O6 position of guanine and has been shown to repair CNU-induced DNA damage. We have previously demonstrated that transplantation of murine bone marrow cells transduced with a recombinant retroviral vector expressing MGMT via the human phosphoglycerate kinase promoter (PGK-MGMT) protects animals in vivo from acute myelotoxicity associated with CNU treatment. In the present study, we examined the effects of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), a commonly used CNU, on long term recovery of the lymphoid compartment, including thymus reconstitution, peripheral T and B cell populations, and lymphocyte mitogen responses in mice reconstituted with PGK-MGMT-transduced hemopoietic cells. Mice transplanted with either mock-infected control or PGK-MGMT-transduced stem cells were treated with five weekly doses of BCNU. Analysis of the lymphoid compartment demonstrated significant damage 3 mo after the last BCNU dose in control animals. In contrast, the profound deficiency in CD4+CD8+ double-positive thymocytes and mature lymphocytes observed in control mice surviving BCNU treatment was completely reversed in mice transplanted with PGK-MGMT-transduced bone marrow and was associated with molecular evidence of in vivo selection of transduced cells in the lymphoid compartment. Thus, long term immunodeficiency following CNU therapy may be prevented by genetic modification of murine hemopoietic stem cells with MGMT, leading to significant improvement in post-transplant immune function.

Animals↗
PubMed1997

Quantitative measurement of resting skeletal muscle [Ca2+]i following acute and long-term downhill running exercise in mice.

Alteration of resting free intracellular [Ca2+] ([Ca2+]i) homeostasis has been implicated in the aetiology of skeletal muscle fibre injury following damaging pliometric (lengthening or 'eccentric') contractions. Quantitative measurements of resting [Ca2+]i in skeletal muscles following acute or long-term exercise involving such injurious contractions have not been performed. We tested the hypothesis that, following an acute bout of pliometric exercise, the maximum force production (Po) of isolated skeletal muscles would be significantly reduced and that this deficit in force would be accompanied by an elevation in resting skeletal muscle [Ca2+]i. Further, we tested whether long-term pliometric exercise training would protect skeletal muscles from contraction-induced injury. Adult male mice were randomly assigned to either, control, 24-hour, 48-hour, or trained groups. The 24-hour and 48-hour group animals were subjected to a single acute downhill treadmill running bout (decline 16 degrees, at a rate of 13 m/min, for 60 min) and sacrificed at 24 or 48 h, respectively. Trained animals underwent a 14 week endurance training program consisting of a daily (5 days/week) downhill running session, under identical conditions to that of the acutely exercised groups. The sedentary control animals remained in their cages. For each animal, Po was determined in the fast-twitch EDL and slow-twitch soleus muscles from one hindlimb and quantitative measurements of [Ca2+]i were made in the contralateral muscles using fluorescence digital imaging microscopy in conjunction with Fura-2. Po was lower in the EDL and soleus muscles from the 48-hour group compared with the control group animals. Po was higher in the EDL muscles of the trained group compared with the 48-hour group. No significant difference in Po was detected in either muscle from the 24-hour or trained groups compared with muscles from control mice. In EDL muscles, [Ca2+]i was elevated in the 48-hour group compared with the control and trained group animals, but was not different between the 24-hour group compared with control mice. [Ca2+]i was not different in the soleus muscles among the 48-hour, trained or control group mice, but was increased in muscles from the 48-hour group compared with the 24-hour group. Endurance downhill running training conferred protection to recruited skeletal muscles against the effects of an acute bout of repeated pliometric contractions, as evidenced by [Ca2+]i and Po values similar to muscles from unexercised control mice.

Animals↗
PubMed1997

Purification and partial characterization of feline trypsin.

Trypsins have been purified and characterized in a multitude of mammalian and nonmammalian species, but not in the domestic cat (Felis catus). In several species two or more isoforms of trypsin have been isolated. Feline trypsin was purified from feline pancrease by sulfuric acid extraction, ammonium sulfate fractionation, gel filtration and affinity chromatography on a benzamidine-activated sepharose gel. Feline trypsinogen was purified by sulfuric acid extraction, SDS-PAGE and electroelution. Only one isoform of feline trypsin and its zymogen could be demonstrated. Isoelectric focusing on agarose gel revealed an isoelectric point of greater than 10.0 for both feline trypsinogen and trypsin. The molecular weight of feline trysinogen was estimated at 22,600, while the molecular weight of feline trypsin was estimated at 21,000. The N-terminal amino acid sequence of feline trypsinogen was Phe-Pro-Ile-Asp-Asp-Asp-Asp-Lys-Ile-Val-Gly-Gly-Tyr-Thr-Asn-Arg. We conclude that cats either have only one isoform of trypsin or that other isoforms are present in minute quantities, undetectable by commonly used methods. We further conclude that feline trypsinogen and trypsin are cationic. Finally, the N-terminal amino acid sequence of the last 16 amino acid residues of feline trypsinogen is closely related to that of other mammalian species and the final 8 amino acid residues (termed trypsinogen activation peptide) are identical to those of canine cationic trypsinogen.

Amino Acid Sequence↗
PubMed1997

Establishing chemoresistance in hematopoietic progenitor cells.

An attractive approach to circumvent chemotherapy-induced myelosuppression is the use of gene-transfer technology to introduce new genetic material into hematopoietic cells. Several pre-clinical studies have demonstrated that increasing the expression of genes encoding proteins that modulate drug resistance in hematopoietic cells provides significant protection against chemotherapy-induced myelosuppression both in vitro and in vivo. Most work in this area has focused on the use of recombinant retroviruses as vectors for the delivery of DNA sequences into hematopoietic stem cells and progenitor cells. Based on these studies, clinical trials are now under way to evaluate the potential use of two gene sequences-multidrug resistance gene 1 and O6-methylguanine DNA methyltransferase. Reducing chemotherapy-induced myelosuppression by increasing the expression of genes that modulate drug resistance via gene transfer into bone marrow cells might allow dose-intensification of chemotherapy, which might result in an improvement in the clinical outcome of patients with high-risk tumors.

Aldehyde Dehydrogenase↗
PubMed1997

Altered basal and adenosine-mediated protein flux from coronary arterioles isolated from exercise-trained pigs.

Solute flux per unit surface area and concentration gradient, (J(S)/SdeltaC), was quantified in arterioles isolated from hearts of sedentary (SED) and exercise-trained (EX) female Yucatan Miniature Swine. Apparent permeability (P(S)) was assessed from measures of J(S)/SdeltaC for two proteins, alpha-lactalbumin (alpha-lact) and porcine serum albumin (PSA), under basal conditions and following 5 min suffusion with 10(-5) M adenosine (ADO). Both proteins were labelled with the fluorescent dye tetramethyl rhodamine isothiocyanate. Basal P(S) to alpha-lact differed with exercise training ((P(S)alpha-lact)SED = 5.2+/-1.8 (median+/-median absolute deviation (MAD), n = 9 pigs) versus (P(S)alpha-lact)EX = 7.4+/-1.1 x 10(-7) cm s(-1), n = 9, P < 0.05). For the larger protein PSA, basal P(S) did not change with training (P(S)PSA)SED = 50+/-1.6, N = 11 vs. (P(S)PSA)EX = 4.1+/-1.2 x 10(-7) cm s(-1), N = 11). Suffusion of the arterioles (33+/-4 microm diameter, n = 18 vessels) from SED hearts (n = 14) with 10(-5) M ADO decreased P(S)alpha-lact 15+/-8% relative to control and was without effect on P(S)PSA. By contrast, in arterioles (39+/-4 microm diameter, n = 22 vessels) from EX hearts (n = 14), ADO increased P(S)alpha-lact and P(S)PSA by 32 and 65% respectively, indicating that receptor-mediated changes in permeability were also sensitive to exercise training. These data demonstrate that, for coronary arterioles, permeability to macromolecules adapts to exercise training. The adaptive mechanisms may involve more than one structural component of the vessel wall as the changes in permeability were size-dependent.

Adenosine↗
PubMed1997

A recombinant human fibronectin fragment facilitates retroviral mediated gene transfer into human hematopoietic progenitor cells.

Gene transfer into hematopoietic progenitor cells is increased when these cells are adherent to the carboxy-terminal chymotryptic fragment of human plasma fibronectin (FN30/35) containing the heparin binding domain (HBD) and the alternatively spliced type three connecting segment (IIICS) region. We report herein the production of a recombinant human fibronectin fragment comprised of the HBD and IIICS regions expressed by Sf9 insect cells following recombinant baculovirus infection. The resulting isolated peptide, HuBacFN, facilitated gene transfer into human hematopoietic cell lines and primary human hematopoietic progenitors to a level achieved with the purified human plasma FN30/35 peptide.

Base Sequence↗