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The interaction of human osteoblast cells with diamond-like carbon films incorporating silicon and silicon oxide (SiO(x), 1 < or = x < or = 1.5) and synthesized using the direct-current plasma-activated chemical vapour deposition method was investigated. Cell culture studies were performed for films with Si contents ranging from approximately 4 at.% to 15 at.%. Substantial differences between Si-incorporated and SiO(x)-incorporated films were found for the bonding environments of Si atoms and the hybridization of underlying carbon structures. However, osteoblast-attachment studies did not show statistically significant trends in properties of cell growth (count, area and morphology) that can be attributed either to the Si content of the films or to the chemical structure of the films. The surface energy decreased by 40% as the Si content of the SiO(x) incorporated DLC films increased to 13 at.%. The cell adhesion properties however did not change in response to lowering of the surface energy. The incorporation of both Si and SiO(x) leads to a beneficial reduction in the residual stress of the films. The average roughness of the films increases and the hardness decreases when Si and SiO(x) are added to DLC films. The impact of these changes for load-bearing biomedical applications can be determined only by carefully controlled experiments using anatomic simulators.

The role of reactive oxygen species (ROS) production on DNA damage and potentiation of fludarabine lethality by the histone deacetylase inhibitor (HDACI) LAQ-824 was investigated in human leukemia cells. Preexposure (24 h) of U937, HL-60, Jurkat, or K562 cells to LAQ-824 (40 nmol/L) followed by fludarabine (0.4 micromol/L) dramatically potentiated apoptosis (>or=75%). LAQ-824 triggered an early ROS peak (30 min-3 h), which declined by 6 h, following LAQ-824-induced manganese superoxide dismutase 2 (Mn-SOD2) upregulation. LAQ-824/fludarabine lethality was significantly diminished by either ROS scavengers N-acetylcysteine or manganese (III) tetrakis (4-benzoic acid) porphyrin or ectopic Mn-SOD2 expression and conversely increased by Mn-SOD2 antisense knockdown. During this interval, LAQ-824 induced early (4-8 h) increases in gamma-H2AX, which persisted (48 h) secondary to LAQ-824-mediated inhibition of DNA repair (e.g., down-regulation of Ku86 and Rad50, increased Ku70 acetylation, diminished Ku70 and Ku86 DNA-binding activity, and down-regulated DNA repair genes BRCA1, CHEK1, and RAD51). Addition of fludarabine further potentiated DNA damage, which was incompatible with cell survival, and triggered multiple proapoptotic signals including activation of nuclear caspase-2 and release of histone H1.2 into the cytoplasm. The latter event induced activation of Bak and culminated in pronounced mitochondrial injury and apoptosis. These findings provide a mechanistic basis for understanding the role of early HDACI-induced ROS generation and modulation of DNA repair processes in potentiation of nucleoside analogue-mediated DNA damage and lethality in leukemia. Moreover, they show for the first time the link between HDACI-mediated ROS generation and the recently reported DNA damage observed in cells exposed to these agents.

In this paper, we review the suitability of diamond as a semiconductor material for high-performance electronic applications. The current status of the manufacture of synthetic diamond is reviewed and assessed. In particular, we consider the quality of intrinsic material now available and the challenges in making doped structures suitable for practical devices. Two practical applications are considered in detail. First, the development of high-voltage switches capable of switching voltages in excess of 10 kV. Second, the development of diamond MESFETs for high-frequency and high-power applications. Here device data are reported showing a current density of more than 30 mA mm(-1) along with small-signal RF measurements demonstrating gigahertz operation. We conclude by considering the remaining challenges which will need to be overcome if commercially attractive diamond electronic devices are to be manufactured.

Interactions between the multikinase inhibitor sorafenib and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) were examined in malignant hematopoietic cells. Pretreatment (24 h) of U937 leukemia cells with 7.5 micromol/L sorafenib dramatically increased apoptosis induced by sublethal concentrations of TRAIL/Apo2L (75 ng/mL). Similar interactions were observed in Raji, Jurkat, Karpas, K562, U266 cells, primary acute myelogenous leukemia blasts, but not in normal CD34+ bone marrow cells. Sorafenib/TRAIL-induced cell death was accompanied by mitochondrial injury and release of cytochrome c, Smac, and AIF into the cytosol and caspase-9, caspase-3, caspase-7, and caspase-8 activation. Sorafenib pretreatment down-regulated Bcl-xL and abrogated Mcl-1 expression, whereas addition of TRAIL sharply increased Bid activation, conformational change of Bak (ccBak) and Bax (ccBax), and Bax translocation. Ectopic Mcl-1 expression significantly attenuated sorafenib/TRAIL-mediated lethality and dramatically reduced ccBak while minimally affecting levels of ccBax. Similarly, inhibition of the receptor-mediated apoptotic cascade with a caspase-8 dominant-negative mutant significantly blocked sorafenib/TRAIL-induced lethality but not Mcl-1 down-regulation or Bak/Bax conformational change, indicating that TRAIL-mediated receptor pathway activation is required for maximal lethality. Sorafenib/TRAIL did not increase expression of DR4/DR5, or recruitment of procaspase-8 or FADD to the death-inducing signaling complex (DISC), but strikingly increased DISC-associated procaspase-8 activation. Sorafenib also down-regulated cFLIP(L), most likely through a translational mechanism, in association with diminished eIF4E phosphorylation, whereas ectopic expression of cFLIP(L) significantly reduced sorafenib/TRAIL lethality. Together, these results suggest that in human leukemia cells, sorafenib potentiates TRAIL-induced lethality by down-regulating Mcl-1 and cFLIP(L), events that cooperate to engage the intrinsic and extrinsic apoptotic cascades, culminating in pronounced mitochondrial injury and apoptosis.

The mechanism and functional significance of XIAP and Mcl-1 down-regulation in human leukemia cells exposed to the histone deacetylase inhibitor vorinostat and the cyclin-dependent kinase inhibitor flavopiridol was investigated. Combined exposure of U937 leukemia cells to marginally toxic concentrations of vorinostat and flavopiridol resulted in a marked increase in mitochondrial damage and apoptosis accompanied by pronounced reductions in XIAP and Mcl-1 mRNA and protein. Down-regulation of Mcl-1 and XIAP expression by vorinostat/flavopiridol was associated with enhanced inhibition of phosphorylation of RNA polymerase II and was amplified by caspase-mediated protein degradation. Chromatin immunoprecipitation analysis revealed that XIAP and Mcl-1 down-regulation were also accompanied by both decreased association of nuclear factor-kappaB (XIAP) and increased E2F1 association (Mcl-1) with their promoter regions, respectively. Ectopic expression of Mcl-1 but not XIAP partially protected cells from flavopiridol/vorinostat-mediated mitochondrial injury at 48 h, but both did not significantly restored clonogenic potential. Flavopiridol/vorinostat-mediated transcriptional repression of XIAP, Mcl-1-enhanced apoptosis, and loss of clonogenic potential also occurred in primary acute myelogenous leukemia (AML) blasts. Together, these findings indicate that transcriptional repression of XIAP and Mcl-1 by flavopiridol/vorinostat contributes functionally to apoptosis induction at early exposure intervals and raise the possibility that expression levels may be a useful surrogate marker for activity in current trials.

The integration of organic and inorganic materials at the nanometre scale into hybrid optoelectronic structures enables active devices that combine the diversity of organic materials with the high-performance electronic and optical properties of inorganic nanocrystals. The optimization of such hybrid devices ultimately depends upon the precise positioning of the functionally distinct materials. Previous studies have already emphasized that this is a challenge, owing to the lack of well-developed nanometre-scale fabrication techniques. Here we demonstrate a hybrid light-emitting diode (LED) that combines the ease of processability of organic materials with the narrow-band, efficient luminescence of colloidal quantum dots (QDs). To isolate the luminescence processes from charge conduction, we fabricate a quantum-dot LED (QD-LED) that contains only a single monolayer of QDs, sandwiched between two organic thin films. This is achieved by a method that uses material phase segregation between the QD aliphatic capping groups and the aromatic organic materials. In our devices, where QDs function exclusively as lumophores, we observe a 25-fold improvement in luminescence efficiency (1.6 cd A(-1) at 2,000 cd m(-2)) over the best previous QD-LED results. The reproducibility and precision of our phase-segregation approach suggests that this technique could be widely applicable to the fabrication of other hybrid organic/inorganic devices.

Extraction of chronically implanted pacing and defibrillator leads is facilitated by using specialized locking stylets placed in the lead to allow application of traction and to stabilize the lead during sheath dissection of fibrotic tissue. We report the initial multicenter series of cases using a novel lead locking device (LLD). In 57 consecutive patients presenting at 6 institutions for lead extraction, 99 leads were treated using the LLD. After removing the pulse generator, leads were severed, the inner coil dilated and an LLD was successfully inserted and locked in the inner lumen of 95/99 (96 %) leads. With traction applied to the LLD, a variety of sheaths were advanced over the lead body to separate it from adhesions. In 97/99 (98 %) leads, all or most of the lead was removed via the implant vein; 2 leads were removed via the femoral vein. No major complications were observed. The LLD deploys safely and reliably, and provides stable support for advancement of dissecting sheaths.

A capillary gas chromatographic-mass spectrometric (GC MS) method is described for the analysis of meperidine using 3,3,5,5-[2H4]-meperidine as an internal standard. Chromatography was performed on a (5% phenyl) methylpolysiloxane column (30 m x 0.32 mm I.D., 0.25 microm film thickness) operated at 195 degrees C; helium carrier gas-50 cm/s(-1), tR = 2.3 min. Ionization was by electron impact (EI) and detection by selected ion monitoring of the molecular ions. The method provided high response linearity (mean r = 0.9982) and precision (< 6.5% C.V.). Application of this method to a pilot study of aqueous meperidine x HCl (10 mg/ml(-1)) stability in a surgically implantable infusion pump at 37 degrees C for 90 days revealed no demonstrable drug degradation.

We present a method for the development of consensus documents describing the components of genetic evaluation and genetic counseling for various diagnoses. These documents were developed to encourage consistency among genetic professionals in Washington State. Other possible uses of these documents are to provide information regarding genetic evaluations for health care practitioners and payers, and to assist in quality assurance and genetic training programs. A working group of six genetic professionals developed two templates for the "critical elements of genetic evaluation and genetic counseling," for clinical (nonprenatal) and prenatal patients. The working group then completed prototype templates for several specific genetic disorders. The templates and prototypes were sent to interested genetic professionals and perinatologists who submitted a total of 76 draft "critical elements" (CE's) to the working group. At two statewide meetings, participating practitioners modified and unanimously approved the CE templates, then unanimously approved the 21 draft CEs that had been finalized in small group discussions. Approved CE's were distributed to genetic professionals and perinatologists within the state.

Objective: To evaluate the relationship between uterine size and a possible increase in operative morbidity and procedure failure rates in women undergoing total vaginal hysterectomy., Methods: A retrospective chart analysis of all hysterectomies performed for histologically confirmed leiomyomata was completed. A total of 128 cases qualified. Patients were stratified into three groups: group I, patients undergoing vaginal hysterectomy with a uterine weight of 300 g or greater but less than 1000 g; group II, patients undergoing vaginal hysterectomy with a uterine weight of 100-299 g; and group III, patients undergoing abdominal hysterectomy with a uterine weight of 100-1000 g. The variables evaluated included the following: length of hospital stay, operative time, estimated blood loss, and operative complications. Data regarding failed vaginal hysterectomy requiring an abdominal approach were also obtained., Results: Both vaginal hysterectomy groups had a significantly reduced length of stay compared with the total abdominal hysterectomy group. There was no significant difference in mean estimated blood loss between groups I and III. Similarly, there were no significant differences in complication rates among the three groups. Group I had an 84% (31 of 37) success rate versus 95% (40 of 42) for group II (not statistically significant). There were no significant differences in the mean uterine weight, estimated blood loss, and complication rate in unsuccessful versus successful vaginal hysterectomies. The estimated blood loss was significantly higher for unsuccessful vaginal hysterectomy., Conclusion: Uterine size alone is not an absolute contra-indication to vaginal hysterectomy. Large uterine size (greater than 300 g) was not related to a significant increase in failed vaginal hysterectomy. Conversely, failed vaginal hysterectomy was not size-dependent. Furthermore, there is no additional operative morbidity when vaginal hysterectomy is converted to a total abdominal hysterectomy because of a technical inability to complete the surgery vaginally.

We found no difference in clinical pregnancy rates following IVF-ET in women with anteverted versus retroverted uteri. Patients can be reassured that the probability of clinical pregnancy following IVF-ET is not compromised by uterine position.

We describe a technique for spectrally and temporally resolving the kilo-electron-volt emission fromultrashort plasmas produced from solid targets with a tabletop terawatt 400-fs laser. The firsttime-resolved Al spectra (near 8 Å) obtained with a 2-ps time resolution are presented. The results clearly demonstrate that the resonance emission width decreases as the plasma density increases. The ultrafast K(α) emission component is also measured in our experimental conditions.

We report on the second trimester prenatal diagnosis of an apparently nonmosaic tetraploid fetus, 92,XXYY. Indications for cytogenetic studies of the fetus included abnormal ultrasound findings and abnormal maternal serum levels of alpha-fetoprotein (AFP)/estriol. Chromosome analysis of amniocytes documented tetraploidy, a finding confirmed by flow cytometry of several fetal tissues. Autopsy findings in the fetus are compared with those of other cases of tetraploidy. To our knowledge this is the first reported prenatal diagnosis of a tetraploid fetus. Additionally, it illustrates the value of flow cytometric analysis of products of conception in which polyploidy is suspected.

In this study rat epigastric island flaps were used as a model to investigate selected tissue biochemical changes occurring during secondary ischemia. It was hypothesized that free radical damage, depletion of free radical scavengers, depletion of ATP, and increased edema might explain differences in flap survival between partial (venous obstruction) and total (arteriovenous obstruction) ischemia and decreased flap survival with increasing ischemia time. Flaps were given 2 hr or primary ischemia, 8 hr of normal perfusion, then secondary ischemia of 0, 2, 4, 8, or 12 hr with either arteriovenous obstruction or venous obstruction. Biochemical analysis of the skin was performed after 0, 24, or 96 hr reperfusion. Only minor differences were found between arteriovenous and venous ischemia for any of five biochemical parameters, despite a previous finding that venous ischemic flaps are more susceptible to necrosis. Levels of xanthine oxidase and malonyldialdehyde (both indices of free radical generation) increased with ischemia time. Levels of superoxide dismutase (a free radical scavenger) correspondingly decreased. Tissue levels of ATP decreased after ischemia and recovered to normal for shorter but not for longer ischemia times after 96 hr of reperfusion in parallel with flap survival. Edema increased immediately after the ischemic insult but decreased once the tissue became necrotic. These results imply roles for free radicals, ATP, and edema in secondary ischemia, but do not distinguish between arteriovenous and venous secondary ischemia.

Elevation of a vascular island flap 24 hours before an ischemic insult (prior elevation) has been shown to significantly increase flap survival, and to decrease blood thromboxane levels, compared with acutely ischemic flaps. The current study considered whether prior elevation causes other biochemical alterations that could be beneficial for flap survival. Tissue levels of adenosine triphosphate (a major tissue energy store), superoxide dismutase (a major defense against free radicals), xanthine oxidase (an enzymatic source of free radicals), and edema were measured. Rat epigastric flaps, with or without prior elevation, had 10 or 12 hours of acute ischemia. Biopsies were taken at 0, 12, or 24 hours after reperfusion. Skin from flaps with no ischemia (control flaps) or control skin was harvested at the same times. Acutely ischemic flaps had significantly lower levels of adenosine triphosphate and less edema than those in prior elevated ischemic flaps after 12 hours of ischemia (both, p less than 0.05). Superoxide dismutase and xanthine oxidase did not vary significantly. It is not clear whether the increased adenosine triphosphate level in prior elevated flaps is the cause or the result of increased tissue viability. Prior elevation did not alter free radical mechanisms. Furthermore, prior elevation was beneficial for flap survival despite increased edema.

To comply with the requirements of the Joint Commission for the Accreditation of Healthcare Organizations (JCAHO) and to facilitate the review process, the authors designed a program to screen for the appropriateness of packed red cell (PRC) and platelet concentrate (PLT) transfusions. The purpose of this report is to describe the methodology of the review process. A quality assurance (QA) monitor was created in the Laboratory Information System (LIS) to screen indicators: hemoglobin for PRCs and platelet count for PLTs. Numerical value limits were defined to determine acceptable ranges. Each week, the LIS compiles a list of all patients who received transfusions and for whom the QA monitor determined that the values of the screened indicators were outside the defined appropriate limits. A detailed transfusion record is generated for each patient identified. During a six-month evaluation of this program, a total of 1,788 PRC and 3,109 PLT units were transfused. Of these, 582 PRC (32.5%) and 2,219 PLT (71.4%) units were within the acceptable guidelines. Lists for the remaining 1,206 PRCs and 890 PLTs were generated. Review of the transfusion record and other laboratory values from the LIS established the appropriateness of 1,052 PRC and 782 PLT transfusions. At the conclusion of the six-month period, the medical charts for 181 (11%) PRC and 108 (4.5%) PLT transfusions required chart review. This method provided major reduction in time of the transfusion review process. Similar guidelines may be used to monitor other transfusion products such as fresh frozen plasma.

Prostacyclin, the stable prostacyclin analogue carbacyclin, the thromboxane synthetase inhibitor UK-38,485, and the phosphodiesterase inhibitor dipyridamole were tested on rabbit epigastric free flaps for their ability to improve flap survival after a period of ischemia. Control flaps infused with a balanced salt solution had a 39.9% survival, whereas prostacyclin, carbacyclin, and dipyridamole significantly increased flap survival to 68.4% (P less than 0.05), 66.4% (P less than 0.05), and 66.9% (P less than 0.05), respectively. UK-38,485 improved survival slightly to 47.6% although not significantly. The improved flap survival correlated with the vasodilatory properties of the three successful agents whereas the antithrombotic properties of UK-38,485 were not sufficient, on their own, to increase flap survival.

We examine the performance of an actively mode-locked Ti:sapphire laser operating in the 1-microm wavelength regime. Pulse durations of 1.7 psec are produced with an average output power of 400 mW. With the use of external dispersion compensation this pulse width has been further reduced to 850 fsec.

This study investigated the efficacy of selected agents in the salvage of experimental skin flaps in rabbits after 21 hours of 25 degrees C ischemia. Calcium channel antagonists nitrendipine, diltiazem, and verapamil increased ischemic skin flap survival in rabbits from 33.3% for buffered saline infused controls to 71.4% (P less than 0.05), 71.4% (P less than 0.05), and 50.0% (not significant) respectively. The beta 2-adrenoceptor agonist salbutamol produced an increase in survival to 64.3%, which narrowly missed statistical significance. All four test agents invoked a vasodilatory response (greatest for nitrendipine, diltiazem, and salbutamol), a slight fall in blood pressure, and a small increase in heart rate. It is concluded that the vasodilatory response in the microcirculation of the ischemic flap helped to minimize the risk of occlusion due to thrombosis or cell sludging during reperfusion, thus leading to improved flap survival.

Silicone tissue expanders were inserted subcutaneously in the buttocks of nine young pigs and gradually inflated to maximum capacity over 5 weeks. On the control side the expanders were left uninflated. Island buttock flaps were then raised, the expanders removed and the flaps spread into the same sites for 10 days. The tissue was harvested. Area measurements and full thickness skin biopsies were taken 10 days after flap inset in order to study the changes in collagen composition and isotypes in the skin layers. Ten days after inset of the flap the expanded skin had a mean 47% increase in surface area, was 9% thinner (from surface to implant), mostly due to thinning of the subcutaneous zone, but was not significantly different in water content, relative to the control skin. The expanded skin had a significant 9.3% increase (p less than 0.01, t test) in collagen content of the dermis. The relative proportions of Types I and III were not significantly changed by skin expansion in either the dermal/epidermal or subcutaneous/capsular zones. It is speculated that tensile factors during expansion stimulate the biosynthetic activity and/or mitotic activity of fibroblasts in the dermis to produce this gain in collagen in the expanded compared with unexpanded tissue.

The rabbit epigastric free flap, subjected to 21 hours of warm (25 degrees C) ischaemia, was used as an experimental model to test the ability of two endothelium-dependent vasodilators, calcitonin gene-related peptide (CGRP) and carbamyl beta-methylcholine chloride (MCh, bethanechol chloride, the stable acetylcholine analogue) to improve flap viability. After the period of ischaemia, flaps were infused intra-arterially with either Hanks balanced salt solution (controls), CGRP or MCh for 30 minutes, and received additional intravenous boluses of these drugs at 2 and 32 minutes after revascularisation. The area of flap surviving improved significantly (p less than 0.025) from 39.9% (n = 18) for controls to 70.2% (n = 14) for CGRP treatment at 2 micrograms/kg, but was unchanged at 47.1% (n = 14) for MCh treatment at 50 micrograms/kg. Both CGRP and MCh significantly increased blood flow (p less than 0.05) resulting in 34% lower peripheral resistances compared with controls. These results suggest that CGRP has considerable clinical potential for the salvage of ischaemic flaps. CGRP must have several, as yet undefined, beneficial effects on the ischaemic tissue, since MCh invoked a vasodilatory response but failed to salvage ischaemic flaps.

Obstructive lymphedema is a pathologic condition resulting in the accumulation and stagnation of serum proteins in the lymphatics and interstitial spaces. In a canine model of obstructive lymphedema, one limb was rendered lymphedematous, and various biochemical parameters were determined in this and an unaffected control limb. Both lymph and interstitial fluid had significantly decreased acid proteinase activity (comprising mostly cathepsin D-like enzymes) and neutral proteinase activity (comprising metallo, sulfhydryl, and serine proteinases, and collagenase). Possible reasons for these decreases could be: (1) saturation of macrophages and their surrounding environment with whole or partially digested proteins, or (2) elevation in the levels of circulating inhibitors like alpha 2-macroglobulin. The lymphedematous skin was significantly thicker than control skin and had elevated levels of collagen. However, unlike some fibrotic conditions, the relative proportions of types I, III, and V collagen, as determined by pepsin solubilization and neutral salt fractionation of the collagen fibrils, were similar to those found in normal skin. It is speculated that a decrease in the breakdown of collagen by collagenase and a continuing synthesis of collagen by fibroblasts led to an imbalance in favor of collagen deposition in the skin.

Rabbit epigastric free flaps were subjected to ischaemia at 25 degrees C for 24 hours. At the time of revascularisation the flaps were infused intra-arterially with one of the following: Hanks balanced salt solution (control), the high energy phosphates PEP/ATP, the thromboxane synthetase inhibitor dazoxiben hydrochloride, the free radical scavenger SOD and a combination of all these agents (treated groups). Control ischaemic flap survival at post-ischaemia day 7 was 23.5%, while the other treatments resulted in improved flap survival of 43.5% (p less than 0.025), 23.5% (not significant), 38.6% (p less than 0.05) and 35.7% (p less than 0.05) respectively. None of these agents improved post-ischaemic blood flow significantly. These results would support the use of PEP/ATP or SOD in the clinical treatment of failing ischaemic skin flaps but do not support the use of dazoxiben hydrochloride.

The present study examined the effect of phosphoenolpyruvate (PEP) and adenosine triphosphate (ATP) on rabbit skeletal muscle flap survival after warm ischaemia. Two muscle flap models, rectus femoris pedicle flap and latissimus dorsi free flap, were subjected to a total ischaemia of 4 hours at 37 degrees C and 20 degrees C, respectively. Immediately prior to revascularisation, the muscles were infused with either Hanks' balanced salt solution (BSS) or Hanks' BSS containing 200 mumol PEP and 6.6 mumol ATP. Quantification of muscle damage was determined by measuring the plasma levels of creatinine kinase (CK), lactate dehydrogenase (LDH), lactate, potassium, and phosphate at 0, 2, 24, and 96 hours after revascularisation. Infusion of PEP/ATP compared with Hanks' BSS alone significantly decreased the efflux of CK in both rectus femoris (P less than 0.025) and latissimus dorsi muscles (P less than 0.05) and of LDH in the rectus femoris muscle (P less than 0.01). No significant changes were observed, however, for the plasma levels of lactate, potassium, and phosphate. From this study it was concluded that PEP and ATP partially protect skeletal muscle from ischaemia and reperfusion injury.

A neuropeptide known as calcitonin gene-related peptide (CGRP) has been shown to have vasodilatory properties in the rabbit epigastric island flap of almost equivalent potency to prostacyclin. The latter is currently regarded as the most potent vasodilator yet to be isolated. CGRP, with its longer-lasting effect in blood and its ability to overcome noradrenaline-induced vasospasm, may be promising for use during or after ischaemic flap transfer or replantation. Another known vasodilatory peptide, atriopeptin, was not as potent in the microvascular bed of the cutaneous flap as in major blood vessels.

1. Canine obstructive lymphoedema was created in one hind leg of 30 dogs by irradiation of the groin and surgical removal of surviving lymph glands and lymphatics. The opposite leg served as a control. Once the oedema had stabilized, groups of 10 dogs were treated orally with 12.5 mg day-1 kg-1 for 8 months with either one of the benzopyrones coumarin (2H-1-benzopyran-2-one) and 7-hydroxycoumarin (7-hydroxy-2H-1-benzopyran-2-one), or placebo. 2. The two benzopyrones significantly (P less than 0.01) but gradually reduced the oedema by 20-30% over 8 months, as judged by circumferential measurements of the oedematous and control limbs. There was no change with the placebo. 3. In the oedematous fluids (lymph and interstitial fluid), benzopyrone treatment reduced the protein content and increased acid and neutral proteinase activity compared with the control limbs, while the levels of the proteinase inhibitor alpha 2-macroglobulin remained unchanged. Furthermore, these active drugs reduced the excess water content, thickness and hydroxyproline content of skin biopsies from oedematous limbs compared with those from control limbs. No changes were observed for the placebo group. 4. These biochemical changes suggest that benzopyrones can reduce the excess proteinaceous fluid in lymphoedema by increasing the levels of proteinase activity relative to the number of proteinase inhibitors. As a secondary event the amount of fibrosis in the skin is also reduced, presumably by an increase in collagenase activity from the mononuclear phagocytes. 5. These results support the hypothesis that benzopyrones activate the production of proteinases by mononuclear phagocytes.(ABSTRACT TRUNCATED AT 250 WORDS)