Fludarabine and cyclophosphamide with filgrastim support in patients with previously untreated indolent lymphoid malignancies

To evaluate the response rate and potential toxicities, a phase II trial was conducted of fludarabine and cyclophosphamide with filgrastim support in patients with previously untreated low-grade and select intermediate-grade lymphoid malignancies. Symptomatic patients with preserved end organ function received cyclophosphamide 600 mg/m(2) intravenous (iv) day 1 and fludarabine 20 mg/m(2) iv days1 through 5, followed by filgrastim 5 microg/kg subcutaneous starting approximately day 8. Treatment was repeated every 28 days until maximum response or a maximum of 6 cycles. Sixty patients, median age 53.5 years, were enrolled. Thirty-seven patients with non-Hodgkin lymphoma (NHL) were stage IV and 6 were stage III. Eleven of 17 patients with chronic lymphocytic leukemia (CLL) were Rai intermediate risk and 6 were high risk. The overall complete response (CR) rate was 51% and the partial response (PR) rate was 41%. Of patients with CLL, 47% achieved a CR and the remaining 53% achieved a PR. Of patients with follicular lymphoma, 60% achieved CR and 32% achieved a PR. Although the toxicity of this regimen was mainly hematologic, significant nonhematologic toxicities, including infections, were seen. Twenty-four patients subsequently received an autologous or allogeneic stem cell transplant. Engraftment was rapid, and there were no noticeable procedure toxicities in the immediate posttransplant period attributable to the fludarabine and cyclophosphamide regimen. Fludarabine, cyclophosphamide, and filgrastim make up a highly active and well-tolerated regimen in CLL and NHL.

Time-dependent effect of glutaraldehyde on the tendency to calcify of both autografts and xenografts

To determine mechanisms responsible for the reduced calcification in short-term glutaraldehyde (Glu)-treated autologous pericardial bioprostheses, we studied the time effect of Glu on subsequent calcification and differences in calcification of autograft and xenograft implants in a rat subcutaneous implantation model. In experiment 1, four groups of bovine pericardial pieces (1 cm2) were prepared: (A) fresh bovine pericardium without Glu, (B) with 15-minute Glu, (C) with 60-minute Glu, and (D) with 120-minute Glu. Seven young male Sprague-Dawley rats were used; each received four bovine pericardial pieces from group A, B, C, or D for subcutaneous implantation. Calcium content of the implants (microgram/mg dry weight) 45 days later was 4.8 +/- 2.9, 29.8 +/- 13.6, 106.3 +/- 13.7, and 176.3 +/- 85.5 in groups A, B, C, and D, respectively (p < 0.05 between any two groups). Experiment 2 used 8 young male Sprague-Dawley rats from different mothers. Each received five subcutaneous skin implants. The five skin implants were prepared as follows: (1) fresh self skin, (2) self skin with 30-minute Glu, (3) self skin with 48-hour Glu, (4) fresh skin of others, and (5) skin of others with 48-hour Glu. After 45 days of implantation, the calcium content of the implants was 1.4 +/- 1.1, 57.9 +/- 35.4, 142.7 +/- 61.4, 1.5 +/- 1.1, and 94.9 +/- 24.1 micrograms/mg dry weight in groups 1, 2, 3, 4, and 5, respectively (p < 0.05 for 1 versus 2, 3, or 5; 2 versus 3, 4, or 5; 3 versus 4; and 4 versus 5).(ABSTRACT TRUNCATED AT 250 WORDS)

Bioprosthetic cardiac valve degeneration: role of inflammatory and immune reactions

Inflammatory and immune reactions are thought to mediate both calcification and biodegradation of bioprosthetic cardiac valve implants. To investigate the mechanisms of implant degeneration, we evaluated the role of inflammatory and immune reactions and the effects of tissue preservative treatment in three series of experiments. In the first experiment, three kinds of implants, i.e. glutaraldehyde-treated autograft Sprague-Dawley (SD) rat skin, xenograft Swiss-Webster (SW) mouse skin, and saline-treated autograft (control) were subcutaneously implanted in ten weanling SD rats, and retrieved after 70 days. There was no significant difference in the level of calcification in the autograft (113.13 +/- 27.09 micrograms/mg dry weight) and xenograft (78.27 +/- 31.53 micrograms/mg dry weight) (p > 0.05), but both differed significantly from the control specimens (1.55 +/- 0.87 micrograms/mg dry weight). In the second experiment, the immunological response to glutaraldehyde-treated bovine pericardium (glut tBP) and glycerol treated bovine pericardium (glyc tBP) implants were tested in vivo and in vitro. A Gore-Tex implant was used as a control. Sections of these materials were implanted to the abdominal muscle wall of Lewis rats, with each group composed of twelve animals. Lymphocytes and sera from the animals were isolated, and histological examination was performed at two or four weeks post-implantation. Collagen type 1 (calf skin) was used as antigen. Tritiated thymidine incorporation was used to measure lymphocyte response to antigen collagen type 1 (calf skin), and an Enzyme Linked Immunosorbent Assay (ELISA) was used to test antibodies. The results showed that lymphocytes from both the glut tBP and the glyc tBP groups responded to collagen type 1. The ELISA results showed that the glyc tBP group produced more antibodies than did the glut tBP group, with the difference being significant at a level of p < 0.02. Histology revealed that the glyc tBP had greater inflammatory changes and collagen degeneration than did the glut tBP. In the third experiment, sections of glut tBP and glyc tBP were implanted subcutaneously in two groups of ten weanling SD rats, and retrieved after 70 days. The results showed that glut tBP caused more calcification (197.04 +/- 83.56 micrograms/mg dry weight) than did the glyc tBP (6.74 +/- 0.55 microgram/mg dry weight), with the difference being significant at a level of p < 0.05. From these investigations it is concluded that tissue treatment prior to implantation was very important in determining the tendency of tissue to calcify, and that there was no obvious relationship between bioprosthetic calcification and immunogenicity.

Spontaneous host endothelial growth on bioprosthetic valves and its relation to calcification

We studied host endothelial growth and calcification of bovine pericardial valve prostheses treated with: (A) 0.625% glutaraldehyde + 4% formaldehyde, (B) 99.5% glycerol or (C) 99.5% glycerol + 4% formaldehyde. Twenty-three stentless chordally supported bileaflet pericardial mitral valves with treatments A (n = 6), B (n = 6) or C (n = 11) were implanted in juvenile sheep for 125-273 days. After sacrifice, the anterior cusp from the annulus to papillary muscle of each valve was examined by scanning electron microscopy for the presence of endothelial cells, and the intrinsic calcification of each valve was determined by measuring calcium (micrograms/mg dry weight) from another 1 cm2 piece of grossly normal cusp. Sixty pieces of 1 cm2 pericardium with treatment A, B or C (n = 20 in each group) were implanted in 30 rats for 70 days. Calcium analysis and histology study of the implants were performed. In sheep, within a similar range of implantation periods, the endothelial growth rate of the valves was the highest in group B, 100% (6/6); group C was 45.5% (5/11) and A 16.7% (1/6). There were no significant differences in calcium among groups A, B and C. In rat implants, the calcium of group B was much lower than that of A or C (B = 6.92 +/- 4.46 vs A = 144.52 +/- 27.66 or C = 240.54 +/- 13.47, P < 0.05) although its histology showed more severe degeneration and inflammatory changes. Pericardial mitral valves treated with glycerol show satisfactory biocompatibility with regard to host endothelial growth and prevention of calcification; however, these tissues show evidence of rapid degeneration.(ABSTRACT TRUNCATED AT 250 WORDS)

Diphenylhydantoin inhibits calcification of bovine pericardial implants and myocardium: a preliminary study

Calcification is a major cause of glutaraldehyde-fixed bioprosthetic valve failure. Recent studies have shown that dystrophic calcification shares basic features with normal bone mineralization, including crystal initiation through the mediation of cell membranes, usually in the form of extracellular vesicles. In this study, we observed that calcification of the myocardium of DBA/2J mice was inhibited or reversed by diets supplemented with 100 mg/kg diet diphenylhydantoin (dilantin) for 70 days, with a calcification incidence of 25% in the dilantin group versus 58% in control. We further studied the effects of dilantin on bioprosthetic valve calcification. Three groups of young male Sprague-Dawley rats (100 g, 9/group) were implanted subcutaneously with 1-cm2 pieces of glutaraldehyde-fixed bovine pericardium. Controls were fed a ground chow for 45 or 90 days postimplantation; experimentals received the same chow for the first 45 days postimplantation and then were fed the same diet supplemented with 1000 mg dilantin/kg for the succeeding 45 days. Calcium content (microgram/mg dry weight) of the implants in the dilantin group was 137 +/- 18.6 versus 214 +/- 34.3 in 90 days control and 79.9 +/- 41.5 in 45 days control (mean +/- SD, P < 0.01 and P < 0.05 respectively, t test). The tibia calcium content of the dilantin group was not significantly different from 90 days control. We conclude that orally administered dilantin inhibits calcification of glutaraldehyde-fixed bovine pericardial implants preferentially. It does not cause decalcification either of implants that have already calcified or of the bones. The anti-calcification effect of dilantin may be associated with its anti-vitamin D effect.

Bovine pericardium versus porcine aortic valve: comparison of tissue biological properties as prosthetic valves

The choice of a bioprosthetic valve substitute remains controversial with the major concern being primary tissue failure after implantation. We compared biological properties of the two most frequently used bioprosthetic valve materials, bovine pericardium and porcine aortic valve, before and 90 days after subcutaneous implantation in rats. Before implantation, tissue collagen and water content were measured in nine pieces of bovine pericardium and porcine valves, each fixed in 0.625% glutaraldehyde; calcium, tissue collagen, and water content were measured in another nine pieces of the same tissues after 90 days' implantation. Bovine pericardium had higher collagen content than that of porcine valve (hydroxyproline, 7.98 +/- 0.05* vs. 4.56 +/- 0.02 micrograms/mg, dry weight) but lesser water content (72.16 +/- 3.22%* vs. 87.36 +/- 1.62%) before implantation (*p < 0.001, mean +/- SD, t test); after implantation, bovine pericardium still maintained higher collagen content (hydroxyproline, 4.89 +/- 0.04* vs. 2.61 +/- 0.06 micrograms/mg, dry weight) but contained the same amount of water (60.24 +/- 5.08% vs. 61.43 +/- 9.00%) and calcium (214.43 +/- 34.34 vs. 199.33 +/- 53.44 micrograms/mg, dry weight) (*p < 0.001, mean +/- SD, t test). We conclude that bovine pericardium has superior intrinsic biological properties for prosthetic valve manufacture. With proper integration of properties and design it will in some applications be superior to the porcine aortic valve.

The role of aromatic hydrocarbons in the genesis of breast cancer

The incidence of breast cancer in women has increased dramatically over the last decade. Epidemiological markers of this increased incidence include: endocrine related phenomena (early menarche, age of first parity and age of menopause); exposure of the breast to X-radiation; and a group of seemingly disparate factors--urban residence, dietary selection and alcohol consumption. Although experimental breast cancer may be induced by estrogenic hormones, X-radiation and aromatic hydrocarbons, only aromatic hydrocarbons have not been previously implicated in human mammary carcinogenesis. The seemingly unrelated human factors can best be understood by examining the role of breast tissue in aromatic hydrocarbon metabolism. Aromatic hydrocarbons are important environmental chemicals produced by the incomplete combustion of hydrocarbons for use in energy production. Benzene, benz(a)pyrene, dibenz(ah)anthracene and 1-nitropyrene, known experimental breast carcinogens, are produced in this way. Human exposure to aromatic hydrocarbon metabolites induces and promotes altered DNA by mechanisms described as increased intracellular pro-oxidant production as well as direct adduction to DNA. The breast is anatomically embedded in a major fat depot which stores and concentrates aromatic hydrocarbons and can metabolize these hydrocarbons to carcinogenic metabolites. Ductal cells concentrate these metabolites and themselves become target cells for carcinogenesis. Some lifestyle factors increase the amount of carcinogens produced or enhance their activity. A unitary model for mammary carcinogenesis in humans as well as in experimental carcinogenesis is hypothesized. If correct, the hypothesis would account for some of the increase in breast cancer incidence in industrial countries--and would suggest environmental and dietary modifications that would inhibit hydrocarbon induced mammary carcinogenesis.

Improved postfixation treatment of glutaraldehyde fixed porcine aortic valves by monosodium glutamate

The use of bioprosthetic valves remains limited due to poor long-term durability primarily because of tissue calcification-associated degeneration. Release of locally cytotoxic residual aldehyde after glutaraldehyde fixation is one of the major causes of this degeneration. In this study, monosodium glutamate was used as postfixation treatment to bind residual aldehyde in order to block its toxic effects. Thirty-six pieces of fresh porcine aortic valves were fixed by 0.625% glutaraldehyde for 14 days, and then 18 of them were treated with 1% monosodium glutamate for another 3 days before they were implanted subcutaneously into the backs of two groups of rats (n = 9 in each group) for 45 and 90 days, respectively. Retrieved specimens were examined grossly, and calcium analysis and measurements of tissue collagen and water content were carried out. The results showed that, compared with glutaraldehyde fixed specimens, monosodium glutamate postfixation treated specimens had less calcification (calcium 104.93 + 50.94 versus 141.58 +/- 58.10 at 45 days and 103.07 +/- 76.48 versus 199.33 +/- 53.44 at 90 days, micrograms/mg dry weight, p < 0.01), higher collagen content (hydroxyproline 5.50 +/- 1.29 versus 3.58 +/- 1.48 at 45 days and 5.64 +/- 0.87 versus 4.25 +/- 0.65 at 90 days, micrograms/mg wet weight, p < 0.01), and higher water content (68.00 +/- 6.95% versus 61.33 +/- 8.83% at 90 days, p < 0.05) (mean +/- SD, paired t test). We conclude that monosodium glutamate couples with residual aldehyde, which significantly reduces calcification of glutaraldehyde fixed porcine aortic valves while preserving a higher tissue collagen and water content after implantation. The preserved tissue collagen and water content of the implants is closer to that of unimplanted native valves.

Improved biocompatibility of bovine pericardium using a new method of cross linking

The authors used glycerol (Gly) as a cross linking agent to treat bovine pericardium (BP) and compared it mechanically (tensile test) and biologically (subcutaneous implantation in rats) with glutaraldehyde (Glu) fixed lonescu-Shiley BP (ISBP). Maximum tensile stress (Stmax) was the same in both groups (n = 12 each), while maximum strain (Snmax) was larger in Gly BP. Calcium content (Ca) was lower and water content of tissue (WC) was higher in implants of Gly BP versus ISBP (n = 9 each). Gly BP appeared more hydrated than ISBP in specimens studied by scanning electron microscopy (SEM). In addition, SEM of three Gly BP mitral valves in sheep showed good growth of endothelial (En) cells. These biomechanical advantages of Gly BP over ISBP suggest that Gly may be a useful substitute for Glu in cross linking bovine pericardial valves.

Aldehyde tanning: the villain in bioprosthetic calcification

Preservation of bioprosthetic valves may play a role in valvular calcification. Subcutaneous implants in rats were used to test the effect of different preservation solutions. Fifty male Sprague-Dawley rats were divided into five groups. Fresh bovine pericardium was treated in one of five ways: group A: 99.5% glycerol for 1 week; group B: as group A, then normal saline wash and 0.25% formaldehyde storage for 24 h; group C: as group A, then normal saline wash and 4% formaldehyde storage for 24 h; group D: as group A, then normal saline wash and 0.625% glutaraldehyde storage for 24 h; group E: 0.625% glutaraldehyde and 4% buffered formaldehyde storage. Treated bovine pericardium was cut into 1-cm2 pieces and washed for 30 min with normal saline before implantation. In each animal, three pieces were implanted in the subcutaneous tissue of the back. After 70 days, retrieved specimens were examined grossly, and X-ray densitometry, calcium analysis, and histological examinations were carried out. The results showed that glycerol-treated tissue (group A) had less calcification (calcium 6.92 +/- 4.46 micrograms/mg dry weight) than other groups: group B (calcium 323.12 + 63.56 micrograms/mg dry weight); group C (calcium 240.65 + 13.47 micrograms/mg dry weight); group D (calcium 232.29 + 13.01 micrograms/mg dry weight). These differences were markedly significant (p less than 0.0001). It appears that aldehydes play an important role in the calcification of bioprosthetic valves. Experience with glutaraldehyde- and glycerol-treated pericardium in valvular applications in sheep support these observations.

Zone II flexor tendon repair: effects of vitamins A, E, beta-carotene

Ninety-six adult Leghorn chickens each had the flexor profundus tendon in each middle toe sharply divided in Zone II with immediate repair (pentobarbital, ketamine anesthesia). Animals were then randomly assigned to receive unsupplemented standard chick chow or the chow supplemented with vitamin A (150,000 IU/kg chow), Vitamin E (1000 IU/kg chow), or beta-carotene (90 mg/kg chow). Eight animals from each of the four groups were examined at 7, 30, or 45 days post repair. After sacrifice, in situ composite wound breaking strength was measured in the amputated toe by constant speed tensiometry. Vitamin A-supplemented animals demonstrated breaking strength more than double that of control at each postoperative test day, while those animals receiving supplemental Vitamin E had breaking strength less than half that of control at Day 7 and Day 45. These results are statistically significant. Tensiometry curves differed markedly at all time points among the groups: Vitamin A curves being broader, higher, and having more spikes. These differences in the tensiometry curves, both qualitative and quantitative, may be due to differences in intrinsic tendon healing or to differences in adhesion formation or a combination of both. beta-Carotene supplementation had modest effect. We conclude that supplemental dietary vitamin A increases the breaking strength of composite tendon wounds and that supplemental dietary vitamin E decreases it.

Supplemental vitamin A prevents the tumor-induced defect in wound healing

To test our hypothesis that supplemental vitamin A would mitigate the impaired healing that occurs in tumor-bearing animals, six groups of C3H mice, eight per group, eating a standard commercial mouse chow ad libitum that supports normal growth, reproduction, and longevity were innoculated with 200,000 C3HBA cells. When tumors measured approximately 6 mm in diameter, the mice were anesthesized and wounded (dorsal skin incisions and subcutaneous polyvinyl alcohol sponges). Twenty-four hours later, two groups (one continued on the chow and the other started on the chow supplemented with 150,000 IU vitamin A/kg chow) underwent local tumor irradiation; two groups, one ingesting the chow, the other the vitamin A supplemented chow, were started on cyclophosphamide therapy; two groups, one ingesting the chow, the other the vitamin A supplemented chow, received neither local tumor irradiation nor cyclophosphamide therapy. An additional two groups ingesting the chow, one group neither innoculated with tumor nor wounded, the other wounded by not innoculated, served as controls. Wound breaking strength and sponge reparative collagen accumulation (assessed by hydroxyproline proline measurement) were used as indicators of wound healing. The mice were killed 12 days after wounding. Tumor presence decreased wound breaking strength and sponge hydroxyproline content; these effects were largely negated by supplemental vitamin A. Local tumor irradiation diminished the adverse effect of tumor on sponge reparative collagen content but to a lesser extent than the supplemental vitamin A. Supplemental vitamin A added to the irradiation effect on healing but irradiation did not add to the vitamin A effect. Cyclophosphamide, a systemic radiomimetic anti-tumor agent, did not alter the impaired wound healing of the tumor-bearing mice. Supplemental vitamin A mitigated the impaired wound healing in the cyclophosphamide-treated tumor-bearing mice. Supplemental vitamin A also moderated the effects of wounding, tumor, and tumor therapies (local irradiation and cyclophosphamide) on the increase in adrenal size, leukopenia, thrombocytopenia, and thymic involution (except the last was not moderated in the cyclophosphamide-treated tumor-bearing rats). The splenic enlargement in the untreated tumor-bearing wounded rats and in those treated with cyclophosphamide was lessened by supplemental vitamin A. We hypothesize that these anti-stress effects of vitamin A underlie, in part, its action in mitigating the impaired wound healing of tumor-bearing mice, including those treated by local irradiation or cyclophosphamide. These findings have implications for the care of patients with malignant tumors.

Structure and expression of the human L-myc gene reveal a complex pattern of alternative mRNA processing

We analyzed in detail the structure of the L-myc gene isolated from human placental DNA and characterized its expression in several small-cell lung cancer cell lines. The gene is composed of three exons and two introns spanning 6.6 kilobases in human DNA. Several distinct mRNA species are produced in all small-cell lung cancer cell lines that express L-myc. These transcripts are generated from a single gene by alternative splicing of introns 1 and 2 and by use of alternative polyadenylation signals. In some mRNAs there is a long open reading frame with a predicted translated protein of 364 residues. Amino acid sequence comparison with c-myc and N-myc demonstrated multiple discrete regions with extensive homology. In contrast, other mRNA transcripts, generated by alternative processing, could encode a truncated protein with a novel carboxy-terminal end.

Effect of supplemental vitamin A on colon anastomotic healing in rats given preoperative irradiation

We studied the effect of dietary supplementation with vitamin A on the healing of colon anastomoses in irradiated bowel. Rats were divided into two groups. Those in the first group were fed a standard chow diet and those in the second group were fed the same diet supplemented with 150 IU vitamin A/g of chow. The rats were maintained on their respective diets throughout the experiment. After 7 days, half the rats in each group underwent abdominal irradiation (200 rads). Seven days later, all of the rats underwent distal colon division and anastomosis under pentobarbital anesthesia. All rats were killed 7 days postoperatively, the colons excised, and bursting strength and hydroxyproline determinations performed on both the anastomotic segment and a normal proximal segment of adjacent colon. There was a significant decrease in the bursting strength at the colon anastomosis (p less than 0.02) and in the collagen content (p less than 0.02) after preoperative irradiation. This effect was mitigated by dietary vitamin A supplementation.

Protective effect of vitamin E in rats with acute liver injury

We have previously shown that supplemental vitamin E has a cytoprotective effect in the liver of rats with chronic CCL4-induced liver cirrhosis. In this study, we hypothesized that vitamin E would have a protective effect in acute liver injury induced by D-galactosamine. D-Galactosamine-induced injury has been thought to be due to a synergistic direct toxic effect and presence of intestinal bacteria and/or endotoxins. D-Galactosamine was used to induce acute "hepatitis" (1.5-2.0 g/Kg body weight, ip). Rats were placed on either standard chow or the same chow supplemented with vitamin E (300 mg DL-alpha-tocopherol/Kg diet) and 6 days later were given D-galactosamine. There was significantly improved early (5-day) survival and late (14-day) survival in the vitamin E-supplemented group. The vitamin E beneficial effect was manifested also by decreased liver fat and collagen content and decreased SGPT level. Because bacterial endotoxins have been implicated as playing a role in the pathogenesis of D-galactosamine hepatitis, the same experiment was carried out using germ-free and conventional rats. There was significantly improved survival in both the germ-free and conventional vitamin E-supplemented groups both at 5 and 14 days. There was no significant difference between conventional and germ-free rats with or without vitamin E supplementation. In summary (a) vitamin E improves the early fat and collagen accumulation in the liver, decreases SGPT level, and improves survival in the D-galactosamine experimental model of acute liver injury in both conventional and germ-free rats; and (b) D-galactosamine toxicity is probably not mediated through intestinal bacteria and/or endotoxins.

Prevention of duodenal ulcer formation in the rat by dietary vitamin A supplementation

We have shown previously that supplemental vitamin A (Vit. A) increases the early inflammatory response to wounding and enhances the collagen content of the intestine of normal and injured rats. We now report the effect of dietary supplementation with Vit. A on the prevention of duodenal ulcer (DU) in rats caused by intragastric administration of cysteamine-HCl. A major way cysteamine-HCl induces DU formation is by enhancing gastric acid secretion. Adult male rats were divided into two groups: (1) rats fed a standard rat Chow (Purina) (15 IU Vit. A/g diet) containing two to three times the National Research Council recommended daily allowance for Vit. A for normal rats; (2) rats fed the same supplemented with 150 IU of Vit. A palmitate per/g Chow. One week later, all rats were given 1 ml of cysteamine-HCl (135 mg) intragastrically. The rats were maintained on their respective diets. Two days later, all rats were killed with ether, the stomach and duodenum excised, and examined for the presence of ulcers. No gastric ulcers were found in either group. There was a statistically significant decrease in the incidence of DUs in the Vit. A-supplemented group when compared to the control group (p less than 0.01) 48 hr following cysteamine-HCl administration; 32% of the Vit. A-supplemented rats developed a DU whereas 74% of rats fed standard Chow had DUs. Most rats had a single DU in the first part of the duodenum, occasionally a second ulcer was noted in the same area. Dietary supplementation with Vit. A had no effect on gastric acid production. In conclusion, our data show that Vit. A dietary supplementation is effective in preventing formation of DUs caused by cysteamine-HCl administration to rats. This effect does not appear to be due to reduction of gastric acid output.

Vitamin A and retinoic acid: induced fibroblast differentiation in vitro

The role of vitamin A in wound healing and fibroplasia has been studied extensively in vivo but the mechanism(s) of its action has not been established. In this study the effect of vitamin A and retinoic acid on fibroblast growth and collagen accumulation in vitro was examined. Vitamin A and retinoic acid added to Balb 3T3 mouse fibroblasts in tissue culture resulted in induction of cell differentiation as manifested by a decrease in cell growth rate, enhanced collagen accumulation, and morphologic differentiation. The results of this in vitro study suggest that the stimulatory in vivo effect of vitamin A and retinoic acid on collagen accumulation and fibroplasia in healing wounds is due in a major way to fibroblast differentiation and enhanced collagen synthesis.

The effect of vitamin E on experimentally induced peritoneal adhesions in mice

Previous studies in our laboratory demonstrated that dietary supplementation with vitamin A enhances peritoneal adhesion formation in mice. Other researchers have shown that vitamin E antagonizes some effects of vitamin A in various systems, eg, wound healing. We investigated our hypothesis that dietary supplementation with vitamin E would decrease peritoneal adhesion formation. Adult mice were divided into the following groups: group 1, which ate a standard chow containing 65 IU of vitamin E per kilogram diet (twice the National Research Council's recommended daily allowance for normal mice); and group 2, which ate the same chow supplemented with vitamin E at 300 IU/kg diet (a nontoxic level). Following peritoneal ligation, all mice were killed on the tenth postoperative day and their peritoneal cavities examined for the presence and extent of adhesions. There was a statistically significant decrease in the incidence and degree of adhesions in the vitamin E-supplemented animals; these data supported our hypothesis.

Effect of dimethyl sulfoxide and glycerol on acute bowel ischemia in the rat

After a 30 minute period of superior mesenteric artery occlusion in adult rats, there was a significant decrease in peritoneal inflammatory reaction, ileus, peritoneal adhesion formation, and histologically proved bowel wall necrosis in animals given intravenous dimethyl sulfoxide at the end of the ischemic period. In contrast, control rats given normal saline solution intravenously demonstrated severe inflammatory reaction, ileus, hemorrhagic peritoneal fluid, extensive adhesion formation, and areas of bowel wall necrosis. Intravenous glycerol did not have the beneficial effect seen with dimethyl sulfoxide. Neither compound was effective when given intraperitoneally. We conclude that intravenous dimethyl sulfoxide has a significant protective effect in rats with acute intestinal ischemia due to the superior mesenteric artery occlusion in the rat.

Morbidity and mortality reduction by supplemental vitamin A or beta-carotene in CBA mice given total-body gamma-radiation

Male CBA mice received graded doses (450-750 rad) of total-body gamma-radiation (TBR) from a dual-beam 137Cs irradiator. Commencing directly after TBR, 2 days later, or 6 days later, groups of mice received supplemental vitamin A (Vit A) or beta-carotene (beta-Car), compounds previously found to reduce radiation disease in mice subjected to partial-body X-irradiation. Given directly after TBR, supplemental Vit A decreased mortality, evidenced by increases in the radiation dose required to kill 50% of the mice within 30 days (LD50/30). In one experiment, Vit A increased the LD50/30 from 555 to 620 rad; in another experiment, Vit A increased the dose from 505 to 630 rad. Similarly, in a third experiment, supplemental beta-Car increased the LD50/30 from 510 to 645 rad. Additionally, each compound increased the survival times, even of those mice that died within 30 days. In addition to reduction of mortality and prolongation of survival time, supplemental Vit A moderated weight loss, adrenal gland hyperemia, thymus involution, and lymphopenia--all signs of radiation toxicity. Delaying the supplementation for 2 days after irradiation did not greatly reduce the efficacy of Vit A; however, delaying supplementation for 6 days decreased its effect almost completely.

Compound 48/80 and the healing of wounds in rats. The effect of timing of drug injections

Wound breaking strength was measured in Long-Evans rats in two settings: in one experiment animals received Compound 48/80 i.p. for 8 consecutive days, starting 1 day before infliction of wound and in the second experiment 48/80 was given for 6 days before wounding. Wound breaking strength was always measured on the seventh day after wounding. There was a significant increase in wound breaking strength in animals treated before incision was made, as compared to controls, saline-treated animals (p less than 0.01). When 48/80 was given one day before incision was made, the breaking strength was significantly decreased (p less than 0.0002). Possible explanation for these opposite results is discussed.

Supplemental vitamin A prevents the acute radiation-induced defect in wound healing

Acute radiation injury leads to thymic involution, adrenal enlargement, leukopenia, thrombocytopenia, gastrointestinal ulceration, and impaired wound healing. The authors hypothesized that supplemental vitamin A would mitigate these adverse effects in rats exposed to acute whole-body radiation. This hypothesis was based on previous experiments in their laboratory that showed that supplemental vitamin A is thymotropic for normal rodents and lessens the thymic involution, lymphopenia, and adrenal enlargement that follows stress, trauma, and neoplasia, largely obviates the impaired wound healing induced by the radiomimetic drugs streptozotocin and cyclophosphamide, lessens the systemic response (thymic involution, adrenal enlargement, leukopenia, lymphocytopenia) to local radiation, and shifts the median lethal dose (LD50/30) following whole-body radiation to the right. To test their hypothesis, dorsal skin incisions and subcutaneous implantation of polyvinyl alcohol sponges were performed in anesthetized Sprague-Dawley rats at varying times following sham radiation or varying doses of whole-body radiation (175-850 rad). In each experiment, the control diet [which contains about 18,000 IU vit. A/kg chow (3 X the NRC RDA for normal rats)] was supplemented with 150,000 IU vit. A/kg diet beginning at, before, or after sham radiation and wounding or radiation and wounding. The supplemental vitamin A prevented the impaired wound healing and lessened the weight loss, leukopenia, thrombocytopenia, thymic involution, adrenal enlargement, decrease in splenic weight, and gastric ulceration of the radiated (750-850 rad) wounded rats. This was true whether the supplemental vitamin A was begun before (2 or 4 days) or after (1-2 hours to 4 days) radiation and wounding; the supplemental vitamin A was more effective when started before or up to 2 days after radiation and wounding. The authors believe that prevention of the impaired wound healing following radiation by supplemental vitamin A is due to its enhancing the early inflammatory reaction to wounding, including increasing the number of monocytes and macrophages at the wound site; possible effect on modulating collagenase activity; effect on epithelial cell (and possible mesenchymal cell) differentiation; stimulation of immune responsiveness; and lessening of the adverse effects of radiation.

Carnitine biosynthesis from gamma-butyrobetaine and from exogenous protein-bound 6-N-trimethyl-L-lysine by the perfused guinea pig liver. Effect of ascorbate deficiency on the in situ activity of gamma-butyrobetaine hydroxylase

The production of carnitine from peptide-bound 6-N-trimethyl-L-lysine (Lys(Me3)) or 4-N-trimethyl-aminobutyrate(gamma-butyrobetaine) perfused through isolated guinea pig livers was investigated. [Methyl-3H] Lys(Me3)-labeled agalacto-orosomucoid (AGOR) and asialofetuin were rapidly taken up and degraded by the perfused liver. Most of the free Lys(Me3) derived from Lys(Me3)-AGOR was released unmodified into the perfusion medium. However, Lys(Me3), arising from Lys(Me3)-asialofetuin was converted mostly to gamma-butyrobetaine and carnitine. gamma-Butyrobetaine added to the perfusion medium was hydroxylated to carnitine by the liver at a rate of 2.3 mumol/h. Guinea pigs maintained on an ascorbate-free diet for 17-60 days showed lowered ascorbate contents in all tissues measured and, coincidentally, a sharp reduction in carnitine levels in kidney, liver, and cardiac, and skeletal muscle. Carnitine production from [1,2,3,4-14C]gamma-butyrobetaine and [methyl-3H]Lys(Me3)-asialofetuin was reduced in perfused livers obtained from ascorbate-deficient guinea pigs. Although hydroxylation of gamma-butyrobetaine to carnitine was effectively depressed in the perfused isolated livers from ascorbate-deficient animals, hydroxylation of [methyl-3H]Lys(Me3) (derived from asialofetuin) to [methyl-3H]3-hydroxy-6-N-trimethyl-L-lysine was unaffected. Prior administration of ascorbate to the medium perfusing the isolated livers caused carnitine biosynthesis from all precursors examined to return to control values.

Effect of supplemental vitamin A on the healing of colon anastomosis

The effect of dietary supplementation with vitamin A on the healing of colon anastomoses was studied. Fifty adult male Sprague-Dawley rats were divided into two groups: (1) rats fed a standard chow which contains the equivalent of about 15 IU vitamin A/g diet; (2) rats fed the chow supplemented with an additional 150 IU vitamin A/g diet. Rats were prefed for 5 days; on Day 6 under ether anesthesia the colon was divided 1-in. distal to the ileocecal junction and then reanastomosed. The rats were maintained on the above diets for 5 days and killed on the sixth postoperative day with ether and the segment of colon containing the anastomosis was resected. In 15 rats of each group, the breaking strength of the anastomosis was measured. In the remaining 10 rats of each group, the bursting strength of the anastomotic site and a segment of normal distal colon was measured. Samples of colon from the anastomotic site and the normal segment were analyzed for hydroxyproline. There was a significant decrease in hydroxyproline content at the anastomotic site when compared to the normal distal colon segment in each group of rats (P less than 0.01). The hydroxyproline content of both normal colon and the anastomotic site was significantly higher in the vitamin A-supplemented rats than in the control diet rats (P less than 0.01). There was also a significant increase in bursting strength in the vitamin A-supplemented rats both of the anastomotic site (P less than 0.01) and of the normal colon segment (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Early history of parenteral nutrition

A historical review is presented of a number of aspects of early animal experiments and clinical trials dealing with the i.v. infusion of whole blood and milk; the nutritional use of i.v. erythrocytes, plasma proteins, protein hydrolysates, amino acids, and glucose; and development and use of i.v. fat emulsions. A brief description of the experience with the nutritional use of i.v. ethyl alcohol is also presented. The important studies beginning in the 1960's by Dudrick, Rhoads, Vars, and Wilmore are described elsewhere by them.

Effects of vitamin A and beta carotene on intra-abdominal sepsis

Vitamin A may play a role systemically and locally in controlling intra-abdominal sepsis. Adult male rats were divided into three groups. Group 1 ate a standard rat laboratory chow (not vitamin A deficient), group 2 ate the same chow supplemented with vitamin A, and group 3 ate the chow supplemented with beta carotene. All animals underwent cecal ligation, and the cecum was perforated either with a 27-gauge or an 18-gauge needle. Vitamin A dietary supplementation had a significant protective effect, which was manifested by improved survival in the animals whose cecum was perforated with an 18-gauge needle, prevention of postoperative hypothermia, maintenance of peripheral WBC counts at normal or above-normal values, and better localization of the intra-abdominal inflammatory process. Dietary supplementation with beta carotene had a lesser protective effect.

Ornithine decarboxylase as an early indicator of in vitro hepatocyte DNA synthesis

The enzyme ornithine decarboxylase, one of the key enzymes involved in polyamine biosynthesis, catalyzes the decarboxylation of ornithine to give putrescine. The activity of this enzyme in an in vitro hepatocyte culture assay system was measured because it is known that ornithine decarboxylase levels increase in instances where active protein synthesis, DNA synthesis, and cell growth is initiated. A good correlation was found between ornithine decarboxylase activity and the rate of tritiated thymidine incorporation into hepatocyte DNA. The increase in enzyme activity precedes the incorporation of tritiated thymidine into DNA (enzyme activity increases 2-3 hr following stimulation of cell growth; whereas the tritiated thymidine uptake increases at about 14-18 hr). Experimental results obtained with this assay system, suggest that hepatocytes from the regenerating liver remnant, grown in vitro, secrete a factor(s) into the culture medium which stimulates DNA synthesis of normal hepatocytes. Use of the increase in ornithine decarboxylase activity in this hepatocyte monolayer culture system confirmed the observation made by several investigators: that the serum of rats which underwent partial hepatectomy contains a factor(s) which stimulates hepatocyte DNA synthesis in vitro. In conclusion, these results suggest that ornithine decarboxylase activity can be used as a sensitive, early indicator of the degree of stimulation of hepatocyte DNA synthesis and thus be of use in determining the effect of various trophic factors on hepatocyte DNA synthesis in vitro.

Regression of C3HBA mouse tumor due to X-ray therapy combined with supplemental beta-carotene or vitamin A

Male CBA/J mice, ingesting a vitamin A- and beta-carotene-sufficient laboratory chow, were inoculated in a hind limb with 2 X 10(5) C3HBA adenocarcinoma cells. When the mean tumor size was 6.2 mm, the mice were divided randomly into groups; some groups received supplemental vitamin A or beta-carotene, some received 3,000 rad local radiation to the tumor, and others received both radiation and one of the supplements. All mice that received only radiation or one of the dietary supplements died within 3 months. When local irradiation and supplemental vitamin A or beta-carotene were coupled, "complete" tumor regression occurred in every case (12/12), and tumor regrowth in and death of the mice occurred in only 1 of 12 in each of these groups during the succeeding 12 months. One year after irradiation and dietary supplementation, half the surviving mice were switched back to the control chow. During the next year, none of the mice remaining on the vitamin A or beta-carotene supplements developed tumors; however, of 6 mice switched from vitamin A, 5 had tumors that reappeared. In contrast, tumors recurred in only 2 of 6 mice after they were switched from beta-carotene. A second experiment yielded similar results. These results show that both vitamin A and beta-carotene supplementation added remarkably to the antitumor effect of local irradiation. beta-Carotene supplementation produced a greater residual antitumor action than vitamin A supplementation after the supplements were discontinued, which may have been due to greater tissue storage of beta-carotene.

Wound healing and thymotropic effects of arginine: a pituitary mechanism of action

Supplemental dietary arginine HCl (ARG-HCl) minimizes immediate post-wounding weight loss, accelerates wound healing, and is thymotropic for uninjured and wounded rats. The present experiments were to determine if arginine-pituitary interactions underlie these effects because arginine is a growth hormone secretagogue. Effects of 1% dietary ARG-HCl supplements (0.5% added to a regular commercial rat diet containing 1.8% ARG, 0.5% in drinking water) were studied in (a) hypophysectomized (hypox) rats supplemented with ACTH, L-thyroxine, testosterone propionate, (b) such hypox rats additionally supplemented with bovine growth (hypox + bGH) hormone, (c) intact rats (Int), and (d) intact rats supplemented with growth hormone (Int. bGH). Group (a) hypox rats healed their wounds as rapidly as intact rats (dorsal skin incision breaking strength, accumulation of reparative collagen in sc polyvinyl alcohol sponges). Group (b) hypox, bGH rats showed increased wound breaking strength and accumulation of reparative collagen in the sc sponges to levels significantly greater than those of intact controls; bGH given to intact controls did not affect these indices of wound healing. Supplemental ARG-HCl given intact rats significantly minimized immediate postoperative weight loss, increased wound breaking strength and sponge reparative collagen accumulation, and increased thymic weight. None of these effects of supplemental ARG-HCl were observed in group (a) hypox rats or group (b) hypox + bGH rats. We conclude that an intact hypothalamic-pituitary axis is necessary for these beneficial effects of supplemental ARG-HCl given wounded rats.

Wound healing accelerated by Staphylococcus aureus

While comparing the effects on wound healing of a heated scalpel with those of the cold scalpel, we discovered that inoculation of rat skin incisions with a strain of Staphylococcus aureus dramatically accelerated the gain in wound strength. The accelerating effect was evident four days postoperatively, was maximal at seven to ten days, and was still present at 28 days. The accelerating effect was correlated with the number of S aureus organisms introduced into the wound, and was found in conventional rats and rats germ free up to the time of monocontamination with S aureus. There was no evidence of infection on gross examination; on histologic examination an occasional microabscess was seen in some rats. There may be both local and systemic mechanisms underlying the S aureus accelerating effect. Seven strains of S aureus with varying characteristics demonstrated the wound-healing accelerating effect. In sharp contrast, Staphylococcus epidermidis (three strains), Staphylococcus hominis (one strain), and Pseudomonas aeruginosa (two strains) did not show this effect. The increases in wound healing due to S aureus were substantially greater than reported previously for any nutritional supplement, drug, or other chemical or physical agent.

Prophylactic and therapeutic actions of supplemental beta-carotene in mice inoculated with C3HBA adenocarcinoma cells: lack of therapeutic action of supplemental ascorbic acid

Decreased tumor incidence, increased latent period, and increased survival time were observed in C3H/HeJ mice fed supplemental beta-carotene for 3 days and then inoculated with 10(4) C3HBA (syngeneic) tumor cells. In addition, C3H/HeJ, C3H/He, and CBA/J mice, fed supplemental beta-carotene beginning immediately after they were inoculated with 2 X 10(5) C3HBA tumor cells, showed decreased tumor growth and increased survival time. When beta-carotene was fed to mice in which palpable tumors were already present, it similarly slowed tumor growth and extended animal survival time. Ascorbic acid supplementation (5 g/kg diet), introduced into the experiment as a possible synergist for beta-carotene's antitumor action, was without therapeutic action when tested in the presence or absence of beta-carotene supplements. The basal diet, a standard commercial mouse chow, contains more vitamin A than the National Research Council's recommended dietary allowance for normal rodents and supports normal growth, reproduction, and longevity of normal mice. The work reported here is the first demonstration of the antitumor action of beta-carotene in animals with a transplanted tumor.

Moloney murine sarcoma virus tumors in CBA/J mice: chemopreventive and chemotherapeutic actions of supplemental beta-carotene

Decreased tumor frequency, increased latent period, and increased rate of tumor regression were observed in male inbred CBA/J mice fed supplemental beta-carotene before and/or after they were inoculated with the Moloney sarcoma virus. When beta-carotene feeding was begun after tumors were already present, it markedly increased the rate of tumor regression. beta-Carotene minimized the virus-induced thymus gland involution that accompanies tumor growth, and this action on the thymus gland was believed to underlie part of beta-carotene's antitumor activity. The basal diet, a standard commercial mouse chow containing more vitamin A than the National Research Council recommends as a daily allowance for rodents, supported normal growth, reproduction, and longevity of normal mice. The work reported here is the first demonstration of the antitumor action of beta-carotene in mice inoculated with an oncogenic virus.

Increased survival due to radioactive estradiol in mice with C3HBA or BW 10232 tumors

The influence of progesterone and estradiol labeled with tritium was studied in mice inoculated with transplantable mammary adenocarcinomas C3HBA or BW 10232. Tumor size, tumor growth rate, and host survival were measured. Radioactive [3H]estradiol administration increased survival time and inhibited tumor growth in mice inoculated with these tumor lines. Tumor growth retardation depended on the amount of radioactivity injected and nonradioactive estradiol was without any salutary effect on tumor size or host survival. Neither survival times nor tumor growth rate were altered by radioactive [3H]progesterone. The underlying mechanism(s) is (are) referable to ionizing radiation by the specific carrier estradiol or to an isotope effect of [3H]estradiol.

A hemostatic scalpel for burn debridement

We studied excision of burns with a new heated scalpel. The disposable blade resemble conventional scalpel blades, except that their edges can be heated and the temperature controlled within narrow limits. The control mechanism compensates "instantaneously" for varying losses of heat depending on the vascularity of the tissues and rate of cutting. Cutting is done by the blade's sharp edge and hemostasis results from direct transfer of heat; no electric currents are generated in the tissues. The blades can be fashioned in variety of shapes and sizes, including those suitable for tangential excisions. The heated scalpel allows excision of third-degree burns in pigs and humans with much smaller loss of blood than when the usual cold surgical scalpel is used. Skin grafts applied immediately after excisions with the heated scalpel had excellent rates of success, similar to those of grafts applied immediately after excisions with the cold scalpel.

Granulopoiesis associated with the C3HBA tumor in mice

Female C3H/HeJ mice were inoculated with syngeneic breast adenocarcinoma cells (C3HBA). A progressive neutrophilia developed as the tumors grew. A linear relationship was demonstrated between the tumor diameter and the extent of the neutrophilia. Local tumor excision caused a rapid fall (3 days) in the neutrophil count. Media conditioned with tumor cells, normal mouse kidney, and bone marrow of normal or tumor-bearing mice were prepared. Tumor cell-conditioned medium was found to have marked stimulating activity for granulocytic colony formation of mouse bone marrow cells. Sera from tumor-bearing mice also had colony-stimulating activity. This finding strongly suggested that the neutrophilia was caused by the release of a neutrophil-stimulating factor from the tumor.

Arginine stimulates thymic immune function and ameliorates the obesity and the hyperglycemia of genetically obese mice

The effect of 6-day dietary arginine supplementation on the weight gain, blood glucose, thymus weight, thymic lymphocyte content, and in vitro thymic lymphocyte immune reactivity was studied in obese (C57BL/6J-OB/)B) and heterozygous lean mice. Control mice were fed a commercial laboratory chow (1.8% arginine content) and drank tap water, while supplemented mice were given 0.5% arginine in the chow and 0.5% arginine solution for drinking. All mice ate and drank ad libitum. Supplemental arginine significantly decreased the weight gain (1.2 g vs. 2.2 g, p less than 0.01) and blood glucose levels (303 mg% vs 236 mg%, p less than 0.02) of the OB/OB mice; no such effects were noted in the lean heterozygotes, all of which had normal blood glucose levels. OB/OB mice had thymus glands which weighed less and contained significantly fewer lymphocytes than their lean littermates. In vitro mitogen-stimulated thymic lymphocyte protein synthetic rates were equal in chow-fed lean and OB/OB mice. In both groups, supplemental arginine significantly increased thymus weight, the number of thymic lymphocytes per gland, and thymic lymphocyte immunoreactivity in vitro. The hormonal secretagogue activity of arginine on the pituitary may explain its beneficial effects on the rate of weight gain, hyperglycemia, and depressed thymic immune function of OB/OB mice.

Chemical debridement of burns: mercaptans

Experiments were conducted using non-enzymatic chemical agents (with emphasis on certain mercaptans), alone, in conjunction with enzymatic agents and/or other nonenzymatic chemicals for debridement of burns. Both in vitro (rats, pigs, humans) and in vivo (rats, pigs) tests were carried out. N-acetylcysteine, penicillamine and cysteine ethyl ester in low to moderate concentrations accelerate the debriding action of bromelain (an enzymatic preparation from pineapple stems) and in higher concentrations, N-acetylcysteine and penicillamine (cysteine ethyl ester was not tested) cause ready separation of the burn eschar from the underlying tissue before solubilization of the eschar is complete (rat) or has occurred (pig). Debridement of 3 degree burns of rats is complete within 4-6 hours; the take of immediately applied syngeneic skin grafts is complete and permanent. This is first time rapid debridement of 3 degree burns permitting immediate successful skin grafting has been accomplished with known defined chemicals. In pigs there is softening of the 3 degree burn eschar by N-acetylcysteine but little, if any, dissolution of the eschar. However, mechanical separation of the eschar from the underlying tissue is accomplished readily with a wooden throat stick with no bleeding. There is a change in color of the superficial layer of the underlying subcutaneous tissue from yellow-light brown to dark brown-black. The debrided areas begin to granulate promptly. The healing of deep dermal burns of pigs is hastened by the application of N-acetylcysteine for a day (beginning 24 hours after burning) while the healing of moderately deep dermal burns is not modified. Unburned skin is not damaged. There is no apparent systemic toxicity associated with the use of N-acetylcysteine for debridement of 10-15% b.s.a. 3 degree burns of rats or 15-20% b.s.a. 3 degree burns of pigs. Major emphasis has been on N-acetylcysteine because of the potential adverse secondary effect of penicillamine and cysteine ethyl ester; N-acetylcysteine is readily metabolized. The use of a keratolytic agent prior to the application of N-acetylcysteine hastens the latter's action. Sulfamylon and sulfadiazine can be used with N-acetylcysteine without interfering with its debriding action. The effects of the mercaptans are likely due largely to their ability to depolymerize connective tissue proteoglycans and proteins, especially at the interface between living and dead tissue.

Vitamin A inhibits some aspects of systemic disease due to local x-radiation

We have previously reported that supplemental vitamin A ameliorates the stress response to a wide variety of noxious agents. The present study was carried out to determine how supplemental vitamin A influences the course of radiation sickness in C3H female mice subjected to 3000 R irradiation of one lower hind limb. All mice ingested a chow diet containing about 13,000 units of vitamin A/kg diet (about half as preformed vitamin A and half as beta-carotene) which supports normal growth, development, and reproduction of normal mice. One hundred fifty thousand units of vitamin A/kg chow was added for the vitamin A supplemented mice. All mice ate and drank ad libitum. The supplemental vitamin A feeding was begun either 3 days before radiation or immediately after radiation. There were no significant differences in the effects of these two regimens. The supplemental vitamin A prevented the weight loss, moderated the adrenal hypertrophy, prevented the thymic involution, and lessened the lymphopenia due to radiation. We conclude that supplemental vitamin A has both prophylactic and therapeutic benefits in radiation-induced disease.

Impaired wound healing in streptozotocin diabetes. Prevention by supplemental vitamin A

Goodson and Hunt showed that wound healing is impaired in streptozotocin (Sz) diabetic rats; we speculated that this impairment results from defective early inflammatory responses to wounding. Because we had shown that supplemental vitamin A stimulates the early inflammatory response to wounding in nondiabetic rats, we studied the effect of supplemental vitamin A on wound healing in rats with Sz-induced diabetes. Male Sprague-Dawley rats were fed a commercial rat chow containing twice the amount of vitamin A recommended by the NRC for healthy rats. The rats ate and drank (tap water) ad libitum. Two-thirds of the rats were injected (intravenously) with Sz 60 mg/kg body weight. All of these rats became diabetic (hyperglycemia greater than 350 mg/dl, hyperphagic, polydipsic, polyuric, glycosuric greater than 2%). Seven days later, half of the Sz-injected rats were continued on the chow (Group 2) while the other half (Group 3) were switched to the chow supplemented with 150,000 units of vitamin A/kg chow. The next day, all were wounded (7 cm skin incisions and s.c. polyvinyl alcohol sponge implants). Similarly wounded saline injected nondiabetic rats ingesting the unsupplemented chow served as controls (Group 1). The wounds of Group 2 rats healed poorly compared to Group 1 (breaking strength of skin incisions, 308 +/- 19 g vs 584 +/- 23 g, p less than 0.001; hydroxyproline of the sponge reparative tissue, 0.87 mg vs 2.40 mg/100 mg sponge p less than 0.001). Supplemental vitamin A (Group 3) did not affect the hyperglycemia, hyperphagia, polydipsia or glycosuria, but increased the breaking strengths of the incisions of the diabetic rats (468 +/- 40 g, p less than 0.001), and the sponge hydroxyproline (2.38 mg/100 mg sponge, p less than 0.001). In another experiment, in which the wounding and start of supplemental vitamin A were delayed until 28 days after streptozotocin administration (50 mg/kg body weight), similar results were obtained. Streptozotocin diabetes also caused a decrease in the cross-linking of reparative collagen as judged by the ratio of breaking strengths of skin incisions before and after formalin fixation. Supplemental vitamin A did not influence this defect. Sz also caused peripheral lymphocytopenia, adrenal hypertrophy and thymic involution which responded to the supplemental vitamin A. Based upon experimental data and theoretical considerations we conclude Sz diabetes causes two defects in wound healing: a) quantitatively (reduction in reparative collagen accumulation) and b) qualitative reduction in the degree of cross-linking of reparative wound collagen. The action of supplemental vitamin A in correcting the impaired wound healing, adrenal enlargement, thymic involution and lymphocytopenia of Sz-diabetic rats is independent of an effect on their disturbed carbohydrate metabolism.

Burn sepsis: bacterial interference with Pseudomonas aeruginosa

The pathogenicity of several strains of Pseudomonas aeruginosa for burned rats (3 degrees scald burns, 20% body surface) following topical application of the bacteria to the burn within 1 hour after burning was established. Following this, it was demonstrated that purposeful infection of such 3 degrees scald burns of rats by a strain of Ps. aeruginosa of low virulence (JB-77) protects the rats from the lethal effect of subsequent (48-hour) topical contamination of the burn by a highly virulent strain of Ps. aeruginosa (VA-134) (p less than 0.001). This finding was confirmed in a similar experiment beginning with germfree rats. When the challenge with the highly virulent Ps. aeruginosa strain was 24 hours (rather than 48 hours) after the burning and topical contamination of the burn with the low virulence strain of Ps. aeruginosa, there was little protection (p N.S.). When burned rats were given the low virulence strain of Ps. aeruginosa by gavage right after burning, there was not protection to subsequent (48 hours) challenge by topical application of the highly virulent strain of Ps. aeruginosa to the burn (11/12 vs 12/12 dying). Our finding that purposeful infection of a 3 degrees burn of rats (conventional and also germfree) by a strain of Ps. aeruginosa of low virulence protects from the lethal effect of subsequent (48-hour) topical contamination of the burn by a highly virulent strain of Ps. aeruginosa is due, we believe, to direct bacterial interference between the two strains of pseudomonas.

Thymic stimulatory actions of arginine

Various arginine HCl supplements (0.5-3%), half added to a basal commercial rodent chow (1.8% arginine) and half to the drinking water, were given to 8- to 9-week-old male CBA/J mice for 6 days. Control animals were fed the basal chow and drank tap water. All mice ate and drank ad libitum. Weight gain and food intake were similar in all groups. All arginine supplements increased significantly: thymic weight (average 22%), thymic lymphocyte content (average 45%), and the in vitro reactivity of thymic lymphocytes judged by the incorporation of 3H-leucine into the TCA-precipitable protein fraction in response to stimulation by phytohemagglutinin and concanavalin A. All these thymic effects resulted from the 0.5% arginine hydrochloride supplement; further increases in arginine supplementation did not increase these effects. These data suggest that supplemental arginine may improve host defence mechanisms and thereby may play an important role in the care of severely injured or ill patients, since it is well established that their defense mechanisms are reduced.