A H2O-producing NADH oxidase from the protozoan parasite Giardia duodenalis

We describe the purification of a H2O-producing NADH oxidase from the protozoan parasite Giardia duodenalis. The enzyme is a monomeric flavoprotein containing flavin adenine dinucleotide in a 1:1 molar ratio with the polypeptide. The NADH oxidase has an apparent molecular mass of 46 kDa and was homogenous as determined by denaturing gel electrophoresis and N-terminal amino acid sequencing. NADPH could substitute for NADH as an electron donor with a K(m) value of 4.2 microM for NADH and 16 microM for NADPH (pH 7.8 at room temperature). With oxygen as the primary electron acceptor under aerobic conditions, the pure enzyme did not produce O.-2 nor H2O2 as stoichiometric products of oxygen reduction, implicating H2O as the end product and obviating the need for superoxide dismutase. The ability to utilise oxygen explains the apparent respiration of the amitochondrial fermentative metabolism of Giardia. Mercurials, flavoantagonists and heavy metals (Cu2+ and Zn2+) inhibited this activity. Under anaerobic conditions the enzyme catalysed electron transfer at lower efficiencies to other electron acceptors including nitroblue tetrazolium, potassium ferricyanide, FAD and FMN, using either NADH or NADPH as electron donors. NADPH, however, was a more efficient electron donor. Cytochrome c was not reduced under any assay conditions used. The enzyme reduced the nitrofuran drugs, furazolidone (an antigiardial) and nitrofurantoin, to their toxic radical forms as determined by EPR. Metronidazole, a nitroimidazole, was not reduced. Pure NADH oxidase did not demonstrate ferredoxin:NAD(P)1 oxidoreductase activity since it could not accept electrons from reduced ferredoxin to regenerate NAD(P)H. The G. duodenalis NADH oxidase may, therefore, function as a terminal oxidase, similar to the mitochondrial cytochrome oxidase, and in the maintenance of an optimum intracellular redox ratio. This report of a flavoenzyme from Giardia places Giardia close to the anaerobic bacteria in evolutionary terms.

Local irrigation with tissue factor pathway inhibitor inhibits intimal hyperplasia induced by arterial interventions

OBJECTIVE

To evaluate the capacity of local irrigation with tissue factor pathway inhibitor (TFPI) to inhibit vessels from neointimal lesion formation following intimectomy or balloon angioplasty.

DESIGN

The common carotid arteries in New Zealand white rabbits were subjected to either intimectomy or balloon angioplasty.

INTERVENTION

Before restoring blood flow, the lumina of the vessels were irrigated with 1 mL of Dulbecco phosphate-buffered saline either with TFPI (100 micrograms/mL [TFPI group, n = 10]) or without TFPI (control group, n = 10).

MAIN OUTCOME MEASURES

The area of neointimal formation and the ratio of the intimal to medial areas (I/M) were determined from elastin-stained sections.

RESULTS

The area of neointima and the I/M ratio were not significantly different at 2 weeks postoperatively. However, at 4 weeks, TFPI-treated vessels demonstrated a significant reduction in the neointimal lesion and the I/M ratio compared with those of controls, following both angioplasty and intimectomy. Transmission electron microscopy showed a lack of platelet aggregation and thrombus formation at the intimal surface in the TFPI-treated vessels.

CONCLUSIONS

Local irrigation with TFPI at the time of arterial interventional therapy inhibits intimal hyperplasia following either balloon angioplasty or intimectomy. We hypothesize that TFPI binds to the injured vessel surface and inhibits the cascade of thrombotic events that promote intimal hyperplasia.

Bcl-2 expression inhibits prostaglandin E2-mediated apoptosis in B cell lymphomas

Apoptosis is a critical mechanism in the maturation and maintenance of the immune system. However, the process by which cells die remains poorly understood. The proto-oncogene bcl-2 is considered important in determining whether cells enter an apoptotic pathway or survive. In this report, we first examined the differential sensitivity of immature (CH31) and mature (CH12) B cell lymphomas to growth inhibition by PGE2. The CH31 cell line was growth inhibited and underwent apoptosis in response to PGE2, unlike its mature counterpart, CH12. Furthermore, endogenous levels of the anti-apoptotic protein Bcl-2 in CH31 cells were low compared with CH12. To further investigate the role of Bcl-2 in PGE2- and cAMP-mediated cell death, a retroviral vector bearing the human bcl-2 gene was introduced into CH31. High expression of Bcl-2 in CH31 had no effect on growth inhibition induced by PGE2 or dibutyryl cAMP. In contrast, increased expression of Bcl-2 completely inhibited PGE2- and cAMP-mediated DNA fragmentation and nuclear condensation. Finally, cell cycle analysis of Bcl-2-expressing CH31 cells demonstrated that PGE2 increased the percentage of cells in G1, and analysis of synchronized populations revealed that PGE2 acts at all phases of the cell cycle to delay normal progression. These results support the hypothesis that apoptosis induced through PGE2 and cAMP signaling is sensitive to regulation by Bcl-2 in CH31 B cell lymphomas. Furthermore, unlike apoptosis, regulation of PGE2- and cAMP-mediated growth inhibition in B lineage cells is a distinct and Bcl-2-independent mechanism.

Bcl-2 expression inhibits prostaglandin E2-mediated apoptosis in B cell lymphomas

Apoptosis is a critical mechanism in the maturation and maintenance of the immune system. However, the process by which cells die remains poorly understood. The proto-oncogene bcl-2 is considered important in determining whether cells enter an apoptotic pathway or survive. In this report, we first examined the differential sensitivity of immature (CH31) and mature (CH12) B cell lymphomas to growth inhibition by PGE2. The CH31 cell line was growth inhibited and underwent apoptosis in response to PGE2, unlike its mature counterpart, CH12. Furthermore, endogenous levels of the anti-apoptotic protein Bcl-2 in CH31 cells were low compared with CH12. To further investigate the role of Bcl-2 in PGE2- and cAMP-mediated cell death, a retroviral vector bearing the human bcl-2 gene was introduced into CH31. High expression of Bcl-2 in CH31 had no effect on growth inhibition induced by PGE2 or dibutyryl cAMP. In contrast, increased expression of Bcl-2 completely inhibited PGE2- and cAMP-mediated DNA fragmentation and nuclear condensation. Finally, cell cycle analysis of Bcl-2-expressing CH31 cells demonstrated that PGE2 increased the percentage of cells in G1, and analysis of synchronized populations revealed that PGE2 acts at all phases of the cell cycle to delay normal progression. These results support the hypothesis that apoptosis induced through PGE2 and cAMP signaling is sensitive to regulation by Bcl-2 in CH31 B cell lymphomas. Furthermore, unlike apoptosis, regulation of PGE2- and cAMP-mediated growth inhibition in B lineage cells is a distinct and Bcl-2-independent mechanism.

Minnesota rickets. Need for a policy change to support vitamin D supplementation

Vitamin D deficiency rickets, once considered the most common disease of early childhood, was reported to have disappeared by the 1960s. However, during a recent 18-month period, seven cases of nutritional rickets were diagnosed in the Twin Cities metropolitan area. All of the patients were born at term and were breastfed without supplementation vitamins. Three of the patients were Caucasian, three were African American, and one was biracial. This case series demonstrates the risk of nutritional rickets in breastfed infants in our northern climate, regardless of race. In hopes of eradicating this completely preventable disease, we advocate a uniform policy of vitamin D supplementation to breastfed infants.

Drug retention following intravesical delivery of fluorouracil therapeutic adhesive in C3H mouse bladder

We have developed a fibrinogen-based, sustained-retention drug delivery system, therapeutic adhesive (TA), for application to resected tumor beds to reduce local tumor recurrences. In this study we evaluated the feasibility, safety and retention of the TA formulated with 5-fluorouracil (5-FU TA) after intravesical administration in a mouse bladder model. Radiolabeled [14C]5-FU TA or [14C]5-FU solution was delivered intravesically to C3H/He female mice. After drug administration, retention of 14C in the bladder was quantified by storage-phosphor autoradiography. A 2.6-fold increase in retention was observed with 5-FU TA when compared with 5-FU solution. The AUC(2 min-5 h) for 5-FU TA was 685 nmol h/mm2 compared with 260 nmol h/mm3 for 5-FU solution. No signs of toxicity in the bladder tissue or treatment-associated adverse effects were observed in the mice.

Repair of calvarial defects with flap tissue: role of bone morphogenetic proteins and competent responding tissues

Bone morphogenetic proteins 2 through 8 have the ability to induce the in vivo transformation of extraskeletal mesenchymal tissue into bone. The aims of this investigation were to determine the optimal responding tissue and the specificity of the inductive effect of bone morphogenetic protein 3. The optimal responding tissue was found to be skeletal muscle. The specificity of this response to bone morphogenetic protein 3 was compared with that of recombinant human basic fibroblast growth factor, recombinant platelet-derived growth factor, and recombinant insulin-like growth factor. Bone morphogenetic protein 3 was the only factor that induced de novo bone formation. This ability to transform muscle into bone was tested in 7 x 7 mm irradiated skull defects in the rat. After 1500 rads of exposure, these defects showed no significant signs of healing by 8 months. When these defects were treated with the microvascular transfer of a nonirradiated muscle flap, they had 8 percent healing at 4 months and 37 percent healing by 8 months. Defects treated with 30 micrograms bone morphogenetic protein 3 (without the muscle flap) achieved 50 percent healing by 4 months and 64 percent healing by 8 months. When the defects were treated with both the muscle flap and bone morphogenetic protein 3, there was 96 percent healing by 4 months and 100 percent healing by 8 months (p < 0.015, compared with bone morphogenetic protein 3 alone at both time points). At 8 months, the transplanted muscle was entirely transformed into bone and healed the skull defect with newly generated bone indistinguishable from the surrounding calvarial tissue. These findings suggest a potential clinical utility of bone morphogenetic protein 3-induced bone formation in skeletal reconstructions. Furthermore, they also show that there is a collaborative requirement for both the osteoinductive factor bone morphogenetic protein 3 and the presence of competent responsive cells in the well-perfused muscle.

Wool and grain dusts stimulate TNF secretion by alveolar macrophages in vitro

OBJECTIVE

The aim of the study was to investigate the ability of two organic dusts, wool and grain, and their soluble leachates to stimulate secretion of tumour necrosis factor (TNF) by rat alveolar macrophages with special reference to the role of lipopolysaccharide (LPS).

METHODS

Rat alveolar macrophages were isolated by bronchoalveolar lavage (BAL) and treated in vitro with whole dust, dust leachates, and a standard LPS preparation. TNF production was measured in supernatants with the L929 cell line bioassay.

RESULTS

Both wool and grain dust samples were capable of stimulating TNF release from rat alveolar macrophages in a dose-dependent manner. The standard LPS preparation caused a dose-dependent secretion of TNF. Leachates prepared from the dusts contained LPS and also caused TNF release but leachable LPS could not account for the TNF release and it was clear that non-LPS leachable activity was present in the grain dust and that wool dust particles themselves were capable of causing release of TNF. The role of LPS in wool dust leachates was further investigated by treating peritoneal macrophages from two strains of mice, LPS responders (C3H) and LPS non-responders (C3H/HEJ), with LPS. The non-responder mouse macrophages produced very low concentrations of TNF in response to the wool dust leachates compared with the responders.

CONCLUSIONS

LPS and other unidentified leachable substances present on the surface of grain dust, and to a lesser extent on wool dust, are a trigger for TNF release by lung macrophages. Wool dust particles themselves stimulate TNF. TNF release from macrophages could contribute to enhancement of inflammatory responses and symptoms of bronchitis and breathlessness in workers exposed to organic dusts such as wool and grain.

Intratumoral radioimmunotherapy of a human colon cancer xenograft using a sustained-release gel

Low tumor uptake and normal tissue toxicity limit the efficacy of RIT for the treatment of solid tumors. In this study, an intratumoral injectable gel drug delivery system for local administration of RIT was evaluated using the LS174T human colon cancer xenograft model in SCID mice. The injectable gel is a collagen-based drug delivery system designed for intratumoral (i.t.) administration, which has previously been shown to enhance drug retention at the injection site and reduce systemic drug exposure. We compared the local (tumor) retention and biodistribution of 111In-labeled NR-LU-10 monoclonal antibody given i.t. in the injectable gel versus simple aqueous solution. 111In gel given i.t. and 111In-NR-LU-10 given intraperitoneally (i.p.) were used as controls. The results showed that tumors treated with 111In-NR-LU-10 gel maintained the highest levels of radioactivity for up to 96 h. At 48 h after the administration of 111In-NR-LU-10 gel i.t., 111In-NR-LU-10 solution i.t., 111In gel i.t., or 111In-NR-LU-10 i.p., the level of radioactivity remaining in each gram of tumor was 98, 49, 45, and 16% of the injected dose, respectively. It was estimated that if 100 microCi of 90Y-NR-LU-10 were administered similarly, tumor treated with 90Y-NR-LU-10 gel i.t. would receive a dose of 90.0 Gy, whereas normal tissues in the same animal would receive a dose of approximately 2.43 Gy. In contrast, if 90Y-NR-LU-10 were delivered i.p., a comparable tumor would receive a dose of 16.8 Gy and corresponding normal tissues would receive 3.36 Gy. Consistent with these estimates, enhanced antitumor efficacy was observed when 90Y-NR-LU-10 gel was administered i.t. Tumor growth delay time was 6.9-fold (P < 0.01) longer in these animals (14.4 days) than in animals treated with 90Y-NR-LU-10 i.p. (2.1 days). Systemic toxicity was also significantly reduced in gel-treated animals as monitored by loss of body weight. This study demonstrated that intratumoral delivery of 90Y-NR-LU-10 gel markedly increased the retention of the radioisotope in tumors, enhanced the antitumor efficacy, and reduced systemic toxicity compared to systemic administration of the radiolabeled antibody. This injectable gel drug delivery system may allow for improvement in the therapeutic index for RIT.

A new prenylated flavonol from the root of Petalostemon purpureus

A new prenylated flavonol, petalopurpurenol (1), and a known dihydroflavonol, petalostemumol (2), have been isolated by DNA scission-guided fractionation of the organic portion of a 20% MeOH/CHCl3/H2O partition of a 50% MeOH/CHCl3 extract of the roots of Petalostemon purpureus. Compound 2 displayed moderate activity in DNA-scission assay. Both compounds 1 and 2 were evaluated for cytotoxicity in a panel of human cancer cell lines. The structures of petalopurpurenol (1) and petalostemumol (2) were determined by spectroscopic analysis.

You can be in Jeopardy

Clinical nurse educators are challenged continually to develop interesting and meaningful education sessions for staff members. At the Mayo Medical Center, Rochester, Minn, clinical nurse educators in the surgical services department created an education session based on the television game show Jeopardy. Staff members found they could remember information presented during the education session more easily because of the game show format.

Prevention of microvascular thrombosis by topical application of recombinant tissue factor pathway inhibitor

Tissue factor pathway inhibitor is a naturally occurring protein inhibitor of factor X and the tissue factor-factor VII complex of the extrinsic pathway of coagulation. The potential of tissue factor pathway inhibitor as a topical antithrombotic agent was evaluated in a rabbit model of thrombosis that combined intimal injury, anastomosis, and a twisted pedicle. In 207 rabbit ears, a near-complete amputation was performed, preserving the central ear artery and vein. The central ear artery was transected, the intima was removed mechanically over a 1-cm length, the artery was anastomosed, and the ear was twisted 360 degrees, wrapping the intact vein around the artery. Before recirculation, the lumen was irrigated on a blinded, randomized basis with either hirudin (100 or 500 units/ml), heparin (50 or 100 units/ml), tissue factor pathway inhibitor (10, 40, 125, or 250 microgram/ml), heparin and tissue factor pathway inhibitor together, or vehicle (control). Upon arterial reflow, the ears were observed for 7 days. Patency rates after 7 days were as follows: hirudin, 30 and 55 percent; heparin, 43 and 50 percent; tissue factor pathway inhibitor, 75 and 90 percent; heparin and tissue factor pathway inhibitor, 75 percent; and vehicle, 6 percent. The higher concentrations of tissue factor pathway inhibitor led to significantly higher patency rates than heparin, hirudin, or control solutions. Electron microscopic evaluation of specimens irrigated with gold- labeled tissue factor pathway inhibitor revealed the inhibitor bound to the injured intimal surface for at least 3 days postoperatively. Coagulation studies showed no change in the clotting profile upon intravascular infusion with tissue factor pathway inhibitor even at the highest dose used topically. We conclude that tissue factor pathway inhibitor is a more effective topical antithrombotic agent than either heparin or hirudin.

An approach to random mutagenesis of DNA using mixtures of triphosphate derivatives of nucleoside analogues

We describe a new method for random mutagenesis of DNA based on the use of a mixture of triphosphates of nucleoside analogues. The method relies on DNA amplification in vitro with Taq polymerase and in the presence of the 5'-triphosphates of 6-(2-deoxy-beta-D-ribofuranosyl)-3,4-dihydro-8H-pyrimido-[4,5-C] [1,2]oxazin-7-one(dP) and of 8-oxo-2' deoxyguanosine (8-oxodG). The newly synthesised triphosphate derivative of dP (dPTP) is an excellent substrate for Taq polymerase (Km = 22 microM versus Km = 9.5 microM for TTP); it is incorporated in place of TTP and, with a approximately fourfold lower efficiency, in place of dCTP. After 30 cycles of DNA amplification, equimolar mixtures of the four normal dNTPs and dPTP yield the following frequencies of the four transition mutations: A-->G (4.4 x 10(-2), T-->C (4.3 x 10(-2), G-->A (1.1 x 10(-2) and C-->T (1.0 x 10(-2). The triphosphate derivative of 8-oxodG (8-oxodGTP) is incorporated opposite template adenine and yields two transition mutations (A-->C and T-->G) at frequencies of 0.8 x 10(-2) and 1.2 x 10(-2) respectively. Reaction mixtures containing dPTP and 8-oxodGTP results in both dP and 8-oxodG-induced mutations and an extensive array of codon changes in the absence of insertions and deletions. The method described differs from previous mutagenesis procedures in three respects: (1) it enables very high frequencies of base substitutions (up to 1.9 x 10(-1) (2) it allows control of the mutational load via the number of DNA amplification cycles and (3) it yields both transition and transversion mutations. The procedure may find application in the generation of libraries of DNA and protein mutants from which species with improved or novel activities may be selected.

Treatment of avascular ulcers with cytokine-induced tissue generation and skin grafting

BACKGROUND

Recombinant platelet-derived growth factor (rPDGF-BB) stimulates migration and proliferation of fibroblasts and smooth muscle cells and induces the rapid development of granulation tissue. This study investigated the use of rPDGF-BB and skin grafting to heal avascular ulcers using a rabbit model. We further investigated the effect of a hyaluronic acid carrier and a vascular pedicle on rPDGF-induced tissue generation in this model.

METHODS

Large avascular ulcers were created on both ears of New Zealand white rabbits. One ulcer was treated with topical rPDGF-BB, the other with control buffer. After 5 or 7 days, the amount of granulation tissue migration from the wound margin was measured, and the wounds were skin grafted. In another group of ulcers, rPDGF-BB treatment was combined with a hyaluronic acid disk or an intact central axial ear artery and vein.

RESULTS

Whereas control wounds generated 1.00 +/- 0.27 mm and 1.75 +/- 0.25 mm of granulated tissue migration from the wound margin by days 5 and 7, respectively, rPDGF-BB treatment increased the amount of granulation tissue migration to 1.88 +/- 0.23 mm and 3.00 +/- 0.86 mm by days 5 and 7 after treatment, respectively (P <0.05 at both time points). Hyaluronic acid disks stimulated 2.50 +/- 0.22 mm of granulation tissue migration by day 7 in controls; when rPDGF-BB was added to the carrier, the migration increased to 4.50 +/- 0.29 mm from the wound margin (P<0.05). Granulation tissue migration was further increased with an intact vascular pedicle: 5.75 +/- 0.48 mm in controls versus 7.75 +/- 0.25 mm with rPDGF-BB treatment (P<0.01). Skin grafts applied to the treated ulcers failed to survive in all groups except those with intact vascular pedicles. CONCLUSIONS. This study demonstrates that rPDGF-BB can increase the amount of granulation tissue generated over an avascular wound. This tissue generation is enhanced by both a hyaluronic acid carrier and a vascular pedicle. A vascular pedicle was required for skin graft survival. This study supports the role of hyaluronic acid in rPDGF-BB induced tissue generation and the requirement of a direct blood supply for functional cytokine-induced tissue generation.

A molecular analysis of PGE receptor (EP) expression on normal and transformed B lymphocytes: coexpression of EP1, EP2, EP3beta and EP4

The E-series prostaglandins (PGEs) are complex lipid regulators of B lymphocyte function. They inhibit the growth of certain B lymphoma lines. We report that heterogeneity with respect to PGE-induced growth inhibition correlates with the maturation state of the B cell lines. Specifically, the pre-B cell line 70Z/3 and the immature lymphoma CH31 are extremely sensitive to PGE2. To a lesser degree, other immature lymphomas (CH33, ECH408.1 and WEHI-231) are sensitive to PGE2. More mature lymphomas (BAL-17, CH12 and CH27) and fully differentiated myelomas (J558 and MOPC-315) are insensitive to PGE2. It is unknown what subtype of PGE receptor(s) (EPs) are expressed by B lymphocytes. It is also unknown if modulation of EP receptor expression could account for the differences in the sensitivity of these B cell lines to PGE2. To investigate these issues, reverse transcriptase polymerase chain reaction, Northern blot and DNA sequencing analyses were employed to obtain a definitive EP receptor subtype profile for these B cell lines, and for normal splenic B lymphocytes. Both normal and transformed B lymphocytes express mRNA encoding EP1, EP3beta and EP4 subtypes of PGE receptors. The B lineage cells do not express EP3alpha nor EP3gamma mRNA. The B cell lines are clonal, indicating that EP1, EP3beta and EP4 mRNA are coexpressed. Surprisingly, quantitative differences in basal EP1, EP3beta and EP4 expression were not observed between B cell lines despite their differing susceptibilities to PGE-induced growth inhibition. Conversely, the polyclonal activator LPS selectively upregulates EP4 mRNA expression in the mature B cell line CH12, but not in the LPS-sensitive pre-B cell line, 70Z/3. The activator LPS does not affect EP1 nor EP3beta mRNA expression. Treatment with dbcAMP, an analog of cAMP, mimics PGE-induced growth inhibition indicating that Gs-coupled EP2 and/or EP4 receptors mediate this inhibitory signal. Indeed, EP2 agonists mimic PGE2-induced growth inhibition unlike IP, EP1 and EP3-selective agonists. These data indicate that EP2 receptors are sufficient for mediating PGE-induced growth inhibition of susceptible B lineage cells.

Renal disease susceptibility and hypertension are under independent genetic control in the fawn-hooded rat

Hypertension, diabetes and hyperlipidemia are risk factors for life-threatening complications such as end-stage renal disease, coronary artery disease and stroke. Why some patients develop complications is unclear, but only susceptibility genes may be involved. To test this notion, we studied crosses involving the fawn-hooded rat, an animal model of hypertension that develops chronic renal failure. Here, we report the localization of two genes, Rf-1 and Rf-2, responsible for about half of the genetic variation in key indices of renal impairment. In addition, we localize a gene, Bpfh-1, responsible for about 26% of the genetic variation in blood pressure. Rf-1 strongly affects the risk of renal impairment, but has no significant effect on blood pressure. Our results show that susceptibility to a complication of hypertension is under at least partially independent genetic control from susceptibility to hypertension itself.

Isolation and structure identification of an active DNA strand-scission agent, (+)-3,4-di-hydroxy-8,9-methylenedioxypterocarpan

A new pterocarpan, (+)-3,4-dihydroxy-8,9-methylenedioxypterocarpan [1], was isolated from the flowers of Petalostemon purpureus by a DNA strand-scission assay-guided fractionation procedure. Compound 1 demonstrated activity in a standard in vitro DNA strand-scission assay, and cytotoxicity toward a KB tumor cell line. Two other related pterocarpans [2, 3] isolated from same plant were found to be moderately active for KB cells, but were inactive in the DNA strand-scission assay. (+)-4-Hydroxy-3-methoxy-8,9-methylenedioxypterocarpan [2] has not been reported previously as a natural product, while (+)-maackiain [3] has been isolated only as an optically inactive racemate along with its optical antipode, the (-)-isomer.

Cloning, characterization, and genetic mapping of the rat type 2 angiotensin II receptor gene

The renin-angiotensin system plays an important role in blood pressure homeostasis, but the contribution of the type 2 angiotensin II receptor (AT2R) is still unclear. The reports that the AT2R gene has been mapped to the X chromosome in human and rat and the previous report of a gene, Bp3, on the X chromosome responsible for an increase in blood pressure have suggested that the rat AT2R gene (Agtr2) could be this gene. To elucidate whether Agtr2 is Bp3, Agtr2 was cloned. A simple sequence repeat in the 3'-flanking region of this gene was identified and used as a genetic marker to map Agtr2 to the X chromosome at 18.1 cM distal to the androgen receptor locus. This map position is outside the confidence interval reported for Bp3, demonstrating that Agtr2 cannot be Bp3. However, these data will enhance the research into the AT2R biology as well as the study of the X chromosome.

Detection of surface free radical activity of respirable industrial fibres using supercoiled phi X174 RF1 plasmid DNA

The ability of a number of respirable industrial fibres, amosite and crocidolite asbestos, refractory ceramic fibres (RCFs) and man-made vitreous fibres (MMVFs) to cause free radical injury to plasmid phi X174 RFI DNA was assessed. The oxidative DNA damage was observed as depletion of supercoiled DNA after fibre treatment was quantified by scanning laser densitometry. The mechanism of fibre-mediated damage was determined by the use of the specific hydroxyl radical scavenger mannitol and the iron chelator desferrioxamine-B. The amosite and crocidolite asbestos caused substantial damage to DNA that was dose-related. The free radicals responsible for the asbestos-mediated DNA damage were hydroxyl radicals, as determined by inhibition with mannitol. Asbestos fibre-mediated damage to DNA was completely ameliorated by the chelation of fibre-associated iron with desferrioxamine-B. The amount of Fe(II) and Fe(III) released by equal numbers of the different fibre types at equal fibre number was determined. The fibres released very small amounts of Fe(II) and there were no significant differences between the fibre types. The fibres released substantial amounts of Fe(III); MMVF 21 released significantly more Fe(III) than any of the other fibres and short fibre amosite also released more Fe(III) than three of the MMVFs and two of the RCFs. When ability to release Fe(II) and Fe(III) was compared with ability to cause DNA damage there was not a good correlation, because only the long amosite and crocidolite caused substantial free radical injury to DNA; this contrasts with MMVF 21 and short amosite being the two fibres that released the greatest amounts of iron. The loss of ability to damage DNA in DSF-B-treated asbestos fibres shows that iron at the surface of asbestos fibres definitely has a role in generating hydroxyl radicals. However, it is clear that some fibres, such as short amosite and MMVF 21, release large quantities of iron without causing free radical damage, whilst neither long amosite nor crocidolite released more iron than the other fibres. The exact role of iron in fibre reactivity therefore remains unresolved, but fibre-bound iron not released from the surface of asbestos could be important. Further research is under way to investigate this possibility.

Intratumoral chemotherapy with a sustained-release drug delivery system inhibits growth of human pancreatic cancer xenografts

This study provides the first evidence that treatment of human pancreatic adenocarcinoma is markedly improved by the intratumoral administration of chemotherapeutic agents in a novel drug delivery system. The effect of chemotherapeutic agents delivered in a sustained-release, protein-based, injectable gel was evaluated on the growth of human pancreatic adenocarcinoma cell line, BxPC-3. In vitro chemosensitivity of BxPC-3 cells exposed for 24 or 72 h to fluorouracil (0.01-5 mM), cisplatin or doxorubicin (0.1-50 microM) and floxuridine, vinblastine, mitomycin or paclitaxel (1.0-100 microM) was compared with that of untreated cells. In vitro chemosensitivity was also studied with fluorouracil and mitomycin in the poorly differentiated PANC-1, human pancreatic cancer cell line. Survival was determined after 7-10 days. All drugs decreased cell growth in a dose-dependent fashion. The efficacy of fluorouracil, cisplatin and doxorubicin increased with prolonged exposure, rendering these drugs most appropriate for a sustained-release preparation. For in vivo studies, athymic nude mice bearing BxPC-3 xenografts were treated either with fluorouracil, cisplatin or doxorubicin in the therapeutic injectable gel containing epinephrine or with vehicle alone administered intratumorally on days 1 and 4. After 28 days, the mice were sacrificed and tumors dissected and weighed. Tumors in mice treated with the injectable gel decreased in size by 72-79% compared with tumors in untreated controls and tumors treated with vehicle alone. Intratumoral injection of drug solution and intraperitoneal injection of drug in the injectable gel did not change tumor size compared with controls. In a drug-retention study, mice were injected intratumorally with [3H]fluorouracil either in the injectable gel or in solution. Sustained radioactivity was observed in tumors injected with the gel, and, conversely, greater radioactivity was detected in the liver and kidneys in mice receiving the radiolabeled solution. These results suggest that the therapeutic injectable gel chemotherapy, when given intratumorally, may improve tumor response with less systemic toxicity in comparison with conventional systemic chemotherapy.

Deformability and CD11/CD18 expression of sequestered neutrophils in normal and inflamed lungs

Neutrophil (PMN) sequestration in the pulmonary microvasculature precedes the migration of these cells into the airspaces in inflamed lungs. Intratracheal instillation of the heat-killed organism Corynebacterium parvum in the rat induces an alveolitis in which PMN constitute 70 to 80% of the total cell count in the bronchoalveolar lavage (BAL). This acute alveolitis results in increased sequestration in the pulmonary microvasculature of 51Cr-labeled PMN when compared with control lungs. The aims of this study were to confirm this increased pulmonary PMN sequestration using unlabeled cells and to assess the function and adhesion molecule expression of such sequestered PMN. We counted the number of PMN and erythrocytes obtained by pulmonary vascular lavage (PVL) and compared the ratio of these two cell types in PVL and peripheral blood (PB) as a measure of the sequestration of PMN in the pulmonary vasculature. Compared with control animals, PVL in C. parvum-treated rats had higher PMN counts, which could not be accounted for by the PB leukocytosis. Sequestration of PMN in the pulmonary microvasculature depends on several factors, including the upregulation of adhesion molecules on both PMN and endothelial surfaces and the ability of the cells to deform when passing through the microcirculation. Cells obtained from the PVL were less deformable than PB cells in control but not in C. parvum-treated animals. The expression of the CD18 integrin on PMN obtained from the PVL of C. parvum-treated animals was increased compared with cells from control animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Intralesional sustained-release chemotherapy with therapeutic implants for treatment of canine sun-induced squamous cell carcinoma

Squamous cell carcinoma (SCC) is the most frequently reported malignant epithelial tumour in dogs. Canine sun-induced SCC represents a useful animal model to evaluate new therapeutic modalities for possible human applications. We evaluated the safety and efficacy of treating sun-induced SCC in dogs with intralesional sustained-released chemotherapeutic gel implants that contained collagen, epinephrine (epi), and either 5-fluorouracil (5-FU) or cisplatin (CDDP). Dogs with large, single SCC or fields of multiple SCC were treated with 5-FU/epi gel for a minimum of three weekly injections. Dogs without a complete response were then treated with CDDP/epi gel for a minimum of three weekly treatments. We treated from one to 11 primary, recurrent, or refractory SCC per dog (tumour size 0.2-92.4 cm2; mean cumulative tumour area of 40.7 cm2 per dog). All dogs had at least 50% reduction in cumulative tumour area after treatment with 5-FU/epi gel. More than half (seven of 13) had complete resolution of SCC after treatment with 5-FU/epi gel or CDDP/epi gel. Minimal local tissue reactions were noted; no systemic toxicity occurred. Sustained-release chemotherapy using intralesional 5-FU/epi gel and CDDP/epi gel therapeutic implants is effective in treating canine sun-induced SCC of the skin.

Echocardiographic characterization of left ventricular adaptation in a genetically determined heart failure rat model

This study uses echocardiography to characterize the pattern of left ventricular hypertrophy in a new hypertensive heart failure-prone rat strain designated SHHF/Mcc-cp (SHHF). M-mode echocardiograms of the left ventricle in nine 10- to 12-month old SHHF rats and nine age-matched spontaneously hypertensive rats (SHR) were compared. Wistar-Kyoto and Sprague-Dawley strains served as the normotensive control group. SHHF rats had significantly greater left ventricular mass than did rats in the normotensive control group. Although left ventricular mass was not different between SHHF and SHR, significant differences were seen in the pattern of left ventricular remodeling as determined by relative wall thickness. These differences in left ventricular remodeling may explain the earlier development of heart failure in SHHF. The different patterns of left ventricular hypertrophy in SHHF and SHR suggests that heart failure in SHHF is not mediated by hypertension alone.

Discovery of betulinic acid as a selective inhibitor of human melanoma that functions by induction of apoptosis

As a result of bioassay-guided fractionation, betulinic acid, a pentacyclic triterpene, was identified as a melanoma-specific cytotoxic agent. In follow-up studies conducted with athymic mice carrying human melanomas, tumour growth was completely inhibited without toxicity. As judged by a variety of cellular responses, antitumour activity was mediated by the induction of apoptosis. Betulinic acid is inexpensive and available in abundant supply from common natural sources, notably the bark of white birch trees. The compound is currently undergoing preclinical development for the treatment or prevention of malignant melanoma.