The protective effect of zinc on rosin and resin acid toxicity in human polymorphonuclear leukocytes and human gingival fibroblasts in vitro.

Combinations of rosin and zinc are used in dentistry as components of periodontal dressings and cements and as root canal sealers. The composition and properties of rosins differ largely depending on source and refinement processes. Rosin (colophony) is composed of approximately 70% resin acids. In order to study the toxic effects of different natural rosins and purified resin acids and the detoxifying effects of zinc, these compounds were analyzed and tested on human polymorphonuclear leukocytes (PMN cells) and human gingival fibroblasts using the radiochromium release method. The rosins and the pure resin acids showed a strong dose-related cytotoxicity, which was inhibited by increased zinc concentrations. The purified resin acids (isopimaric, levopimaric, and neoabietic acid) were more toxic than the natural rosins. The contents of these resin acids might explain the difference in toxicity of the rosins tested. It is concluded that rosin and zinc are not to be considered inert compounds and that the cytoprotective effects of zinc and its role in dentistry products merit further investigations.

Bilateral chronic compartment syndrome in the forearm and the hand.

We report two cases of bilateral chronic exertional compartment syndrome (CCS) in the forearm and hand. Measurement of the intramuscular pressure was useful for diagnosis. These two cases illustrate that bilateral CCS should be suspected in patients complaining of bilateral exercise-induced pain in the anconeus muscle, the forearms, the thenar and hypothenar regions and in the first dorsal interosseous muscle. Fasciotomy relieved the pain in both cases.

The use of a water extract from the bark of Choerospondias axillaris in the treatment of second degree burns.

Burns are common in Vietnam, and because of economic constraints and limited resources for the import of appropriate treatments, the health authorities are obliged to rely on traditional herbal remedies. It is therefore essential to evaluate current drugs, one of which is the water extract of the bark of the tree Choerospondias axillaris. It has been used for many years in the Vietnam-Sweden hospital at Uong Bi in northern Vietnam. We assessed the efficacy of the remedy in an open, randomised controlled clinical trial, in which 20 patients with second degree burns were treated with the extract of the Choerospondias axillaris and 19 with saline gauze. The mean healing time was significantly shorter for patients treated with Choerospondias axillaris (11 days) compared with patients treated with saline gauze (17 days) (p < 0.01), and the number of wound infections was significantly lower in the Choerospondias axillaris group (7/20 compared with 16/19, p = 0.003). The bark extract was easy to apply and additional wound care was not usually necessary, while the treatment with saline gauze was laborious for both patients and staff and was much more expensive. The extract from Choerospondias axillaris is a convenient treatment for second degree burns in both children and adults.

Toxic effects of some conifer resin acids and tea tree oil on human epithelial and fibroblast cells.

The present study was undertaken to assess and compare the in vitro cytotoxic effects of three resin acid analogues: dehydrobietic acid, podocarpic acid, O-methylpodocarpic acid; an essential oil from Australia (tea tree oil); and tapped oleoresin from Thailand, on human epithelial and fibroblast cells, using a quantitative neutral red spectrophotometric assay. All of the investigated compounds except for tea tree oil exhibited a cytotoxic activity which was proportional to their concentrations and time of exposure up to 24 h, i.e. higher concentrations and longer time of exposure caused increased cell death. Dehydroabietic acid and the oleoresin were the most toxic compounds followed by O-methylpodocarpic acid, whereas podocarpic acid and tea tree oil showed a lower level of toxicity. On the basis on these findings it is concluded that an isopropyl group on the aromatic C-ring is of great importance for the cytotoxicity of the tested abietane resin acids, thus indicating that the cytotoxic activity of oleoresins most probably is caused by synergistic or additive effects of resin acids. The results from this work support the view that antibacterial activity parallels cytotoxic activity which suggests a similar mode of action, most probably exerted by membrane-associated reactions.

Neutralizing effect of zinc oxide on dehydroabietic acid-induced toxicity on human polymorphonuclear leukocytes.

The cytotoxic effect of dehydroabietic acid (DHAA), a resin acid found in rosin, was studied on human polymorphonuclear leukocytes (PMN) using leakage of 51Cr from prelabeled cells, supravital staining, and transmission electron microscopy. DHAA caused a strong dose-related release of 51Cr, a high uptake of trypan blue, and total cell necrosis as seen in transmission electron microscopy. Albumin slightly reduced the toxic effects, whereas the addition of zinc in various forms strongly inhibited these toxic effects of DHAA in the concentration range 10-500 micrograms/mL. In the presence of albumin, zinc oxide as a suspension inhibited the damage of the cell membranes more than a filtrate of zinc oxide, indicating a subsequent slow release of zinc from the zinc oxide.

Neutralizing effect of zinc oxide on dehydroabietic acid-induced toxicity on human polymorphonuclear leukocytes.

The cytotoxic effect of dehydroabietic acid (DHAA), a resin acid found in rosin, was studied on human polymorphonuclear leukocytes using leakage of 51Cr from prelabeled cells, supravital staining, and transmission electron microscopy. DHAA caused a strong dose-related release of 51Cr, a high uptake of trypan blue, and total cell necrosis, as seen in transmission electron microscopy. Albumin slightly reduced the toxic effects, whereas the addition of zinc in various forms strongly inhibited these toxic effects of DHAA in the concentration range of 10-500 micrograms/mL. In the presence of albumin, zinc oxide as a suspension inhibited the damage of the cell membranes more than a filtrate of zinc oxide, indicating a subsequent slow release of zinc from the zinc oxide.

Effect of topical zinc oxide on bacterial growth and inflammation in full-thickness skin wounds in normal and diabetic rats.

The effects of topical zinc oxide on bacterial growth and inflammation were studied in full-thickness excised cutaneous wounds in normal rats and in hyperglycemic alloxan-diabetic rats. Two concentrations of zinc oxide in a gauze compress (15 or 60 mg/g) were applied to the wounds of the normal rats, but only the higher concentration was used for the diabetic rats. The polymorphonuclear leukocyte count, the alkaline phosphatase activity and bacterial counts in the granulation tissue were recorded on postoperative day 4. In the normal rats there was no significant intergroup difference in polymorphonuclear leukocyte density, though alkaline phosphatase activity was significantly depressed in those treated with the higher zinc oxide concentration. Bacterial growth in granulation tissue decreased at both zinc oxide concentrations. None of these effects was found in the diabetic rats. The results indicate that hyperglycemic diabetic rats respond differently to local zinc oxide treatment than do normal rats, and that the antibacterial activity of zinc oxide in vivo is not solely due to a direct toxic effect on the bacteria.

Antibacterial effects of zinc oxide, rosin, and resin acids with special reference to their interactions.

The growth inhibiting capacity of zinc oxide combined with ordinary rosin (Portuguese rosin), abietic acid or dehydroabietic acid was studied using two different methods. To mimic the actual treatment of wounds, circular tapes or sensitivity discs were placed on Müller-Hinton-agar plates that had been seeded with various facultative aerobic bacteria, and the zones of inhibition were measured. The agar dilution method was used to measure the minimum inhibitory concentration (MIC). Inhibition of growth was restricted to Gram-positive facultative aerobic bacteria for the individual substances zinc oxide, Portuguese rosin, or resin acids, as well as for combinations of these. In general the combination of zinc oxide and dehydroabietic acid was a more potent antibacterial substance than the corresponding combination of zinc with rosin or abietic acid. These combinations commonly had synergistic antibacterial effects.

Inhibitory effect of zinc oxide on contact allergy due to colophony.

Contact allergy to a wound dressing with an adhesive mass consisting of colophony, zinc oxide and rubber (Mezinc) was studied in 179 patients with a history of eczema. 12 patients were found to be allergic to colophony, whereas only 4 of these patients also showed a positive patch test reaction to the wound dressing. 14 patients with verified moderate contact allergy to colophony were patch tested with adhesive mass (10%), Portuguese colophony (10%), zinc oxide (10%), purified resin acids (10%), and Portuguese colophony (10%), in combination with zinc oxide. Only 3 patients reacted to the adhesive mass, whereas all patients showed a positive patch test reaction to Portuguese colophony. A combination of zinc oxide (10%) with Portuguese colophony (10%) provoked a positive patch test reaction in only 5 of these 14 patients. An allergic reaction to abietic acid (90-95% purity) was found in 7 patients and to neoabietic acid (99 + %) in 3 patients, whereas no reactions to dehydroabietic (99 + %), isopimaric (99 + %) or levopimaric acids (98 + %) were found.

Antibacterial effect of zinc oxide in vitro.

Antibacterial activity, zinc concentrations and pH were measured in Müller-Hinton broth containing different amounts of zinc oxide and inoculated with Staphylococcus aureus (10(6) colony forming units/ml). The minimum inhibitory concentrations (MIC) of zinc oxide to different clinical isolates were determined using the Müller-Hinton agar dilution tests. Gram-positive bacteria were most susceptible. Gram-negative aerobic bacteria and streptococci were usually not inhibited even at the highest concentrations used (1024 micrograms/ml), but staphylococci--particularly some isolates of Staphylococcus epidermidis--were sensitive enough to allow determination of their MIC.

Antibacterial activity of rosin and resin acids in vitro.

The antibacterial effects of rosins and resin acids were studied in vitro using three methods, disc diffusion on agar, agar dilution, and broth dilution. Rosin and some resin acids had antibacterial effects that were restricted to Gram-positive bacteria. The abietic type of acids had a more pronounced antibacterial activity than the pimaric and labdane acids when the disc diffusion method was used but there was no inhibition of growth of Gram-negative bacteria. Among the individual resin acids, dehydroabietic acid was generally the most potent, when disc diffusion on agar was used, and prediffusion increased the inhibitory effect. The composition of the pure resin acids dehydroabietic, neoabietic, and isopimaric acid did not change during the experiment, but abietic and levopimaric acid were converted into dehydroabietic acid by the addition of Müller-Hinton agar. In conclusion the old tradition of treating wounds with pitch, sap, rosin, or rosin containing tapes might therefore have some antibacterial relevance.

The effects of occlusive dressings on inflammation and granulation tissue formation in excised wounds in rats.

The effects on the healing of full-thickness excisional wounds treated with either of two occlusive dressings (Mezinc or Duoderm) were compared with the effects of gauze soaked in saline. The wounds were made on 86 rats and were examined clinically, histologically and biochemically four, eight and twelve days after wounding. Four days postoperatively the Duoderm-treated wounds differed significantly from the other two groups. Clinically, an adherent discolored gelatinous mass remained after removal of the firm part of the Duoderm dressing. Histologically it corresponded to a superficial exudate containing polymorphonuclear leukocytes (PMNs), macrophages and condensed foreign material. There was also a more extensive inflammatory reaction in the underlying tissues compared with gauze or Mezinc treatment and debris was seen in vesicles extracellularly and in foamy macrophages. Foamy macrophages were only seen in the Duoderm-treated wounds. These macrophages were mainly confined to the granulation tissue, which was about twice as thick as in the other two treatment groups twelve days after excision.