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Biomedical subjects

A Fenselau

Publications and source records attributed to A Fenselau.

At least 19 recordsLinked to original sources
PubMed1992

The effect of bovine basic fibroblast growth factor on skin flap survival in rats.

Basic fibroblast growth factor (bFGF) was prepared from bovine pituitary glands and evaluated for its effect on the viability of pedicle skin flaps in rats. Pedicle flaps measuring 3 x 7.5 cm and based cephalad were created on the backs of animals. The treatment group received bFGF in saline solution intradermally by Dermo-jet injection 30 minutes before flap elevation. Skin flaps treated with a single application of 80 U of bFGF demonstrated a significant increase in viability from 40.8% to 69.7% of the flap area (p less than 0.001); the flaps treated with 16 U of bFGF exhibited little improvement. Intradermal administration of bFGF to pedicle skin flaps produced an increase in viability that approximates the increase obtained by a surgical delay procedure; treatment of flaps with exogenous bFGF may offer advantages over surgical delay procedures.

Animals↗
PubMed1983

Vitreous: an inhibitor of retinal extract-induced neovascularization.

One of the major problems in assessing neovascularization in mammalian experimental animal models is the immunologic response of the host to stimuli from nonautologous species. Hence, crude bovine vitreous and retinal extracts may produce a complex immune reaction when tested in the rabbit. To circumvent this problem, the chicken chorioallantoic membrane (CAM) assay is most appropriate. In this study the CAM assay for angiogenesis has been modified to study antiangiogenic substances. The modified assay is described in detail and used to demonstrate for the first time the inhibition by adult bovine vitreous of neovascularization induced by extracts of adult bovine retina. In addition to vitreous, three common glycosaminoglycans (keratan sulfate, chondroitin sulfate C, and hyaluronic acid) were assayed for antiangiogenic activity. The results indicate that vitreous inhibition of retinal extract-induced neovascularization is dose dependent, while the sulfated glycosaminoglycans tested had no antiangiogenic activity. A commercial preparation of bovine vitreous hyaluronic acid exhibited a slight, but not statistically significant, inhibitory activity. When vitreous extracts were digested with hyaluronidase, no loss of antiangiogenic activity occurred. These results suggest that the inhibitor of angiogenesis from adult vitreous is probably not a common glycosaminoglycan. The results are consistent with the hypothesis that antiangiogenic substance(s) in vitreous and angiogenic components from retina may act as natural antagonists in controlling the process of retinal neovascularization.

Animals↗
PubMed1981

Tumor angiogenic factor. Purification from the Walker 256 rat tumor.

We report here the purification of an angiogenic substance from the Walker 256 rat ascites tumor which is mitogenic for fetal bovine aortic endothelial cells in culture and which also stimulates new blood vessel growth in vivo. Purification was monitored in endothelial cell cultures by cell counting or by [3H]thymidine incorporation into DNA. Lyophilized crude tumor cell homogenate was extracted with absolute ethanol, and the extract was further purified by silica gel column chromatography. The most purified material eluted with ethyl acetate:methanol (25:1) and behaved as a single component when analyzed either by thin layer chromatography with both silica gel and polyethylene-imine-cellulose systems or by reversed phase (C18) high pressure liquid chromatography. Bio-Gel P-30 chromatography indicates a Mr 400-800 for the active material. The mitogenic activity of the purified material was observed with the vascular endothelial cells cultured in serum-less as well as serum-containing media. The angiogenic activity of this material was revealed in both the chicken chorioallantoic membrane and rat corneal micropocket bioassays. Our results demonstrate that a factor with mitogenic and angiogenic activities can be purified from the Walker rat tumor by a novel, facile, and high yield process.

Angiogenesis Inducing Agents↗
PubMed1981

Nucleoside requirements for the in vitro growth of bovine aortic endothelial cells.

The nutritional needs of cultured fetal bovine aortic endothelial cells were studied with regard to their nucleotide metabolism. When Medium 199 containing calf serum was supplemented with up to 5 microgram/ml of the deoxyribo- or ribonucleosides found in DNA or RNA, the rate of endothelial cell growth increased. The effect was entirely attributable to the pyrimidine nucleosides. The combination of deoxythymidine and deoxycytidine was much more effective than either deoxyribonucleoside used alone or than the combination of uridine and cytidine. Addition of deoxythymidine and deoxycytidine (each at 1 microgram/ml) to the medium supported the growth of endothelial cell cultures from initially sparse populations (ca. 50 cells/cm2), even at low concentrations (1%) of fetal bovine serum. The pyrimidine deoxyribonucleosides on their own were unable to stimulate cell growth; other bonafide growth stimulatory factors, such as those present in serum, serum dialysates, or retinal extracts, were needed in the medium to signal the initiation of DNA synthesis and cell replication. The significance of these findings with respect to improving cell performance under in vitro conditions and controlling endothelial cell growth in vivo are discussed.

Animals↗
PubMed1981

A corneal micropocket assay for angiogenesis in the rat eye.

A corneal micropocket assay for angiogenesis in the rat eye is described in detail. With our test system, a partially purified, low molecular-weight endothelial cell growth stimulatory factor isolated from the Walker 256 rat carcinosarcoma is demonstrated to have potent angiogenic activity in vivo. The advantages and applications of our rat corneal assay are discussed.

Animals↗
PubMed1980

Demonstration of vasoproliferative activity from mammalian retina.

Vasoproliferative activity has been demonstrated in extracts of retinas from human, bovine, and feline sources. These retinal extracts are capable of stimulating (a) proliferation and thymidine uptake of bovine vascular endothelial cells in culture and (b) neovascularization on the chick chorioallantoic membrane. Extracts of skeletal muscle, cardiac muscle, and liver lack similar stimulatory activity. The activity is nondialyzable, stable at 56 degrees C, and inactivated at 100 degrees C. Retinal extracts stimulate the proliferation of corneal fibroblasts but have no effect on the proliferation of vascular smooth muscle cells. Indirect evidence suggests the liberation of a vasoproliferative factor from retina in several ocular disorders. The data in this report represent the first direct demonstration of vasoproliferative activity from mammalian retina.

Animals↗
PubMed1976

3-oxo acid coenzyme A-transferase in normal and diabetic rat muscle.

The amounts of succinyl-CoA--3-oxo acid CoA-transferase (EC 2.8.3.5) decrease progressively in skeletal muscle in streptozotocin-diabetic rats, reaching after 10 days about 50% of the value in normal rat muscle. Electrofocusing studies indicate the occurrence of partial proteolysis of the enzyme in diabetic muscle. However, several functional parameters relating to acetoacetate utilization, including substrate inhibition, are quite similar for muscle transferase preparations from normal and diseased rats. The development of pathological ketoacidosis is discussed in the light of these observations.

Acetoacetates↗
PubMed1976

Subcellular localization of acetoacetate coenzyme A transferase in rat hepatomas.

Succinyl coenzyme A:acetoacetate coenzyme transferase (EC 2.8.3.5), an initiator of ketone body usage and absent in normal liver, has been shown to be located in mitochondria from Morris hepatoma 7288ctc using differential and density gradient centrifugation. Furthermore, tumor mitochondrial subfractionation revealed that this transferase is associated with the matrix-soluble proteins. Comparison of the amounts of total transferase activity in several other hepatomas with the amounts found in the corresponding isolated mitochondria suggests that the results with the 7288ctc tumor pertain generally. The mitochondrial localization of coenzyme A transferase indicates the probable use of ketone bodies as energy sources for the hepatomas.

Acetyl Coenzyme A↗
PubMed1976

Growth stimulation of cultured endothelial cells by tumor cell homogenates.

Short-term cultures of endothelial cells from fetal bovine heart and aorta consistently display increased growth rates when crude tumor cell homogenates from the Walker 256 adenocarcinoma (ascites and solid forms as well as tumor cells from a suspension culture) are added to the culture media. The tumor-derived material produces growth stimulation in both sparse and confluient endothelial cell cultures. Homogenates of embryonic tissues and cultured cells show similar growth-promoting effects; corresponding material from various adult tissues is ineffective. The nonendothelial cells that were tested generally show no growth response or only a slight positive growth response to the tumor cell homogenates. The results indicate the feasibility of using this in vitro system as a paradigm of the tumor-induced vascularization process.

Adenocarcinoma↗
PubMed1975

Acetoacetate coenzyme A transferase activity in rat hepatomas.

The presence of succinyl-coenzyme A:acetoacetate CoA transferase (CoA transferase) (EC 2.8.3.5), an initiator of ketone body utilization in nonhepatic tissue, was examined in liver from normal, partly hepatectomized, neonatal, and tumor-bearing rats, as well as in a series of transplantable rat hepatomas ranging widely in growth rate. While levels of CoA transferase are extremely low in normal, host, and regenerating liver, considerable amounts of activity are detectable in neonatal liver and in the hepatomas. In fact, the content of CoA transferase in the series of Morris hepatomas increases progressively with increase in tumor-growth rate. The fastest-growing tumor studied (7288Ctc) contains about the same amount of CoA transferase activity as rat skeletal muscle (i.e., an activity of about 0.1 mumole of acetoacetate used per min per g tissue). These results clearly indicate that the faster-growing hepatomas have adequate capacity to utilize ketone bodies in bioenergetic or biosynthetic activities. Furthermore, the enzymes from normal and hepatoma 7288Ctc tissues are quite similar with respect to (a) size of about 10(5) daltons, (b) reaction mechanism requiring formation of an enzyme:CoA intermediate (from ping-pong kinetic data), and (c) various kinetic parameters (such as Michaelis constants, product competitive inhibition constants, and acetoacetate substrate inhibition). The enzymes from rat skeletal muscle and Morris hepatoma 7288Ctc have the same isoelectric point (7.6), which differs from that for the rat heart enzyme (6.8).

Acetoacetates↗
PubMed1974

Comparative studies on 3-oxo acid coenzyme A transferase from various rat tissues.

1. Tissue activities, intracellular distribution as well as selected kinetic and molecular properties of succinyl-CoA-3-oxo acid CoA transferase (EC 2.8.3.5), which is an initiator of ketone body usage, were examined in rat kidney, heart, brain, skeletal muscle and liver. 2. The activities of the transferase in these tissues are similar to reported values and are somewhat affected by the homogenization medium. Higher recoveries of activity are obtained when a phosphate buffer is used during the homogenization; Tris solutions containing sucrose and mannitol lead to only slightly lower recoveries, but can be used in studies to determine the subcellular localization of the transferase activity. 3. A close correlation was observed between the relative activities of citrate synthase (a mitochondrial marker enzyme) and CoA transferase in the cytoplasmic, particulate and mitochondrial fractions from the five tissues. 4. The K(m) values for acetoacetate (measured in two different ways), the ratio of V(max.) values for the two enzyme-catalysed half-reactions, and succinate product inhibition are quite similar for the enzyme from each tissue. 5. The enzymes are also similar in molecular weight (with an approx. mol.wt. of 100000 as determined by gel filtration). All show an active band in isoelectric-focusing studies with pI 7.6, except for the enzyme from heart (pI 6.8). 6. The results demonstrate a mitochondrial origin for CoA transferase in these rat tissues and support the proposition that CoA transferase is a ketolytic enzyme, i.e. an enzyme uniquely involved in the complete oxidation of ketone bodies. The structural and functional similarities of these transferases suggest that factors other than differences in K(m) values account for differences in the utilization of ketone bodies by various tissues.

Acetoacetates↗