Degradation of extracellular matrix and its components by hypobromous acid.

EPO (eosinophil peroxidase) and MPO (myeloperoxidase) are highly basic haem enzymes that can catalyse the production of HOBr (hypobromous acid). They are released extracellularly by activated leucocytes and their binding to the polyanionic glycosa-minoglycan components of extracellular matrix (proteoglycans and hyaluronan) may localize the production of HOBr to these materials. It is shown in the present paper that the reaction of HOBr with glycosaminoglycans (heparan sulfate, heparin, chondroitin sulfate and hyaluronan) generates polymer-derived N-bromo derivatives (bromamines, dibromamines, N-bromosulfon-amides and bromamides). Decomposition of these species, which can occur spontaneously and/or via one-electron reduction by low-valent transition metal ions (Cu+ and Fe2+), results in polymer fragmentation and modification. One-electron reduction of the N-bromo derivatives generates radicals that have been detected by EPR spin trapping. The species detected are consistent with metal ion-dependent polymer fragmentation and modification being initiated by the formation of nitrogen-centred (aminyl, N-bromoaminyl, sulfonamidyl and amidyl) radicals. Previous studies have shown that the reaction of HOBr with proteins generates N-bromo derivatives and results in fragmentation of the polypeptide backbone. The reaction of HOBr with extracellular matrix synthesized by smooth muscle cells in vitro induces the release of carbohydrate and protein components in a time-dependent manner, which is consistent with fragmentation of these materials via the formation of N-bromo derivatives. The degradation of extracellular matrix glycosaminoglycans and proteins by HOBr may contribute to tissue damage associated with inflammatory diseases such as asthma.

Diabetic ketoacidosis in a case of pheochromocytoma.

A 31-year-old woman was admitted to our hospital because of diabetic ketoacidosis (DKA). Ultrasound sonography revealed the existence of the left adrenal tumor and endocrinological examinations established a diagnosis of pheochromocytoma. She had been healthy and there was no evidence for gestational diabetes in her personal history. Characteristic features were not found in her tumor size and the catecholamine levels as compared with typical cases of pheochromocytoma. An overwhelming secretion of catecholamine might suppress insulin secretion, as evidenced by the improvement after the resection of the tumor. However, a significant insulin resistance continued after tumor resection. Obesity and the heterozygosity of beta3-adrenergic receptor gene (Try64Arg) might play a role in insulin resistance, which resulted in DKA at least in part. Literature survey revealed four cases of DKA in the patients with pheochromocytoma including ours, three of which were Japanese. Pancreatic capacity to secrete insulin has been reported to be less than Caucasians, which might be another reason for DKA. Thus, we speculate that both suppressed insulin secretion and insulin resistance deteriorated by obesity or other factor(s) such as abnormality in beta3 adrenergic receptor probably depress beta-cell function resulting in abnormal metabolic imbalance such as DKA.

The use of artificial dermis on the donor defect of the free forearm flap.

Microsurgical grafting of a free flap is an established technique of surgical reconstruction. The forearm free flap is frequently used following removal of oral and/or pharyngeal tumors. However, simple split-thickness skin grafting on full-thickness defects of the skin on the flexor side of the forearm results in deformations, pigmentation, and the adhesion of the graft to the tendons. The authors attempted to minimize such problems by repairing the flap donor site with a collagen sponge used as an artificial dermis. This artificial dermis was used to reconstruct postoperative defects in the skin of 5 patients. Split-thickness skin measuring 0.25 to 0.30 mm was grafted onto the defect. The donor site skin was successfully repaired in 2 to 3 weeks without adverse effects, without the development of depressed deformations, and with only slight pigmentation. The artificial dermis formed a matrix on the donor wound bed, with good cosmetic results.

The effects of endothelin-1 on flap necrosis.

In reconstructive surgery, flap necrosis is a major obstacle. The vasospasm in microvascular circulation can be one of the causes of flap necrosis. The vascular endothelium has an important role in the regulation of vascular tone by producing vasodilating and vasoconstricting factors. Endothelin-1, a 21-amino acid polypeptide isolated from the vascular endothelium, is reported to be one of the most potent vasoconstrictors. The purpose of this study was to determine the significance of endothelin-1 on flap necrosis using a rat skin flap. First, we introduced into the experiment endothelin-1 and ETA receptor antagonists, FR139317, then we tried to determine the time course changes of endothelin-1 levels in the flap. Endothelin-1 antagonist had no effect on survival length, although endothelin-1 injection clearly reduced survival length. The combined treatment of antagonist and injection suppressed the effect of endothelin-1 in reducing survival length. Endothelin-1 levels in the flap base significantly increased from 6 hours, and its levels in the flap periphery presented no remarkable changes. These results may suggest that endothelin-1, especially that produced in the flap base, exerts a major effect on flap microcirculation.

Endothelin-1 production by normal human cultured keratinocytes and its regulation.

The possibility that cultured keratinocytes produce endothelins were investigated. The results showed that cultured keratinocytes derived from normal human skin produce endothelin-1. Moreover, keratinocyte endothelin-1 production was completely inhibited by the presence of actinomycin D in the medium. As in the case of endothelial cells, recombinant interleukin-1beta was capable of promoting endothelin-1 production in keratinocytes, whereas herapin inhibited it. Thrombin also inhibited endothelin-1 production. These results indicate that the mechanism of endothelin-1 production in keratinocytes is slightly different from the mechanism in vascular endothelial cells.

The sticker-type temperature indicator in digital replantation: simplified application.

A sticker-type skin-surface temperature indicator, commercially available in Japan, has been utilized to monitor temperature changes in replanted digits. In clinical application, the authors evaluated several shortcomings in some of these devices. For example, the 10-mm diameter indicator is too small for numbers to be seen clearly. The 18-mm diameter indicator is too large to patch onto the finger pulp. To improve this device, the authors used only the number 33 from the 18-mm diameter indicator and applied it to several study subjects. Judgments about the circulatory status of the replanted digit can be made on the basis of the indicator color. The 18-mm diameter indicator, now modified to use only the number 33, is in common use for all the authors' digital replantation cases. Clinicians' ability to see critical temperature changes has been markedly improved, even under poor lighting conditions.

Collagenolytic activities of cultured human malignant melanoma cells.

Three human malignant melanomas were cultured in pure populations and one tumor was cloned into melanotic and amelanotic cell lines. In the homogenates of these cultured cells, specific collagenase activities were demonstrated by isotope release from 14C-labeled collagen, disc electrophoresis, and specific cleavage of collagen molecules as demonstrated in the segment long spacing form. No significant collagenase activity was observed in the culture media. Interestingly, early cultures had a high collagenase activity in the cells and as they were successively subcultured, the activity diminished. Cysteine completely inhibited the degradation of tropocollagen as determined by disc electrophoresis and EDTA partially inhibited the degradation. It is concluded that human malignant melanoma cells produce a specific collagenase in vitro which can be extracted in early culture directly from the homogenate.

Effect of vitamin B6 deficiency on collagen metabolism in rats.

The effects of VB6 deficiency on collagen metabolism were studied using young and adult rats. It was observed in VB6 deficient rats, that both the amount of urinary hydroxyproline and salt soluble fraction of skin collagen decreased. Furthermore, decrease of the alpha-component and increase of the beta-component were also found in the soluble collagen. However, the activity of plasma amine oxidase was lower and the aldehyde content in the acid soluble collagen were also lower than the control group. These changes were revealed more clearly in young growing rats than in adult rats. Based on these results, it may be that VB6 participates in the allysine (alpha-amino-adipic-delta-semialdehyde) formation which is considered as the first step of collagen maturation and also in the synthesis of protocollagen peptide chains.