Sevelamer attenuates the progression of coronary and aortic calcification in hemodialysis patients

BACKGROUND

Cardiovascular disease is frequent and severe in patients with end-stage renal disease. Disorders of mineral metabolism may contribute by promoting cardiovascular calcification.

METHODS

We conducted a randomized clinical trial comparing sevelamer, a non-absorbed polymer, with calcium-based phosphate binders in 200 hemodialysis patients. Study outcomes included the targeted concentrations of serum phosphorus, calcium, and intact parathyroid hormone (PTH), and calcification of the coronary arteries and thoracic aorta using a calcification score derived from electron beam tomography.

RESULTS

Sevelamer and calcium provided equivalent control of serum phosphorus (end-of-study values 5.1 +/- 1.2 and 5.1 +/- 1.4 mg/dL, respectively, P = 0.33). Serum calcium concentration was significantly higher in the calcium-treated group (P = 0.002), and hypercalcemia was more common (16% vs. 5% with sevelamer, P = 0.04). More subjects in the calcium group had end-of-study intact PTH below the target of 150 to 300 pg/mL (57% vs. 30%, P = 0.001). At study completion, the median absolute calcium score in the coronary arteries and aorta increased significantly in the calcium treated subjects but not in the sevelamer-treated subjects (coronary arteries 36.6 vs. 0, P = 0.03 and aorta 75.1 vs. 0, P = 0.01, respectively). The median percent change in coronary artery (25% vs. 6%, P = 0.02) and aortic (28% vs. 5%, P = 0.02) calcium score also was significantly greater with calcium than with sevelamer.

CONCLUSIONS

Compared with calcium-based phosphate binders, sevelamer is less likely to cause hypercalcemia, low levels of PTH, and progressive coronary and aortic calcification in hemodialysis patients.

Pathophysiology of vascular calcification in chronic kidney disease

Patients with chronic kidney disease (CKD) on dialysis have 2- to 5-fold more coronary artery calcification than age-matched individuals with angiographically proven coronary artery disease. In addition to increased traditional risk factors, CKD patients also have a number of nontraditional cardiovascular risk factors that may play a prominent role in the pathogenesis of arterial calcification, including duration of dialysis and disorders of mineral metabolism. In histological specimens from the inferior epigastric artery of dialysis patients, we have found expression of the osteoblast differentiation factor core binding factor alpha-1 (Cbfa1) and several bone-associated proteins (osteopontin, bone sialoprotein, alkaline phosphatase, type I collagen) in both the intima and medial layers when calcification was present. In cultured vascular smooth muscle cells, the addition of pooled serum from dialysis patients (versus normal healthy controls) accelerated mineralization and increased expression of Cbfa1, osteopontin, and alkaline phosphatase to a similar magnitude as does beta-glycerophosphate alone. However, a lack of inhibitors of calcification may also be important. Dialysis patients with low levels of serum fetuin-A, a circulating inhibitor of mineralization, have increased coronary artery calcification and fetuin-A can inhibit mineralization of vascular smooth muscle cells in vitro. These data support that elevated levels of phosphorus and/or other potential uremic toxins may play an important role by transforming vascular smooth muscle cells into osteoblast-like cells, which can produce a matrix of bone collagen and noncollagenous proteins. This nidus can then mineralize if the balance of pro-mineralizing factors outweighs inhibitory factors.

Early healing events in a porcine model of contaminated wounds: effects of nanocrystalline silver on matrix metalloproteinases, cell apoptosis, and healing

A porcine model of wound healing was employed to examine the impact of nanocrystalline silver-coated dressings on specific wound healing events. Full-thickness wounds were created on the backs of pigs, contaminated with an experimental inoculum containing Pseudomonas aeruginosa, Fusobacterium sp., and coagulase-negative staphylococci, and covered with dressing products either containing silver or not. Nanocrystalline silver-coated dressings promoted rapid wound healing, particularly during the first several days post-injury. Healing was characterized by rapid development of well vascularized granulation tissue that supported tissue grafting 4 days post-injury, unlike control dressed wounds. The proteolytic environment of wounds treated with nanocrystalline silver was characterized by reduced levels of matrix metalloproteinases. Matrix metalloproteinases have been shown to be present in chronic ulcers at abnormally high levels, as compared with acute wounds, and may contribute to the nonhealing nature of these wounds. Cellular apoptosis occurred at a higher frequency in the nanocrystalline silver-treated wounds than in wounds dressed with other products. The results suggest that nanocrystalline silver may play a role in altering or compressing the inflammatory events in wounds and facilitating the early phases of wound healing. These benefits are associated with reduced local matrix metalloproteinase levels and enhanced cellular apoptosis.

The role of Acticoat with nanocrystalline silver in the management of burns

Silver is an effective antimicrobial agent, but older silver-containing formulations are rapidly inactivated by the wound environment, requiring frequent replenishment. These older formulations may also be pro-inflammatory and may delay healing. Acticoat (Smith & Nephew, Hull, UK) is a relatively new form of silver antimicrobial barrier dressing which helps avoid the problems of earlier agents. It has rapid and sustained bactericidal activity, and because of this may reduce inflammation and promote healing. Despite extensive testing and clinical experience, no evidence has emerged of resistance or cytotoxicity to nanocrystalline silver. This article collects together a number of presentations that were given at the 2003 European Burns Association Meeting on the use of Acticoat in the management of burns.

Antimicrobial effects of photodynamic therapy on patients with necrotic pulps and periapical lesion

This study analyzed the antimicrobial effect of photodynamic therapy (PDT) in association with endodontic treatment. Twenty patients were selected. Microbiological samples were taken after accessing the canal, endodontic therapy, and PDT. At the end of the first session, the root canal was filled with Ca(OH)(2), and after 1 week, a second session of the therapies was performed. Endodontic therapy gave a mean reduction of 1.08 log. The combination with PDT significantly enhanced the reduction (1.83 log, p = 0.00002). The second endodontic session gave a similar diminution to the first (1.14 log), and the second PDT was significantly more effective than the first (p = 0.002). The second total reduction was significantly higher than the second endodontic therapy (p = 0.0000005). The total first + second reduction (3.19 log) was significantly different from the first combination (p = 0.00006). Results suggest that the use of PDT added to endodontic treatment leads to an enhanced decrease of bacterial load and may be an appropriate approach for the treatment of oral infections.

Treatment of hyperphosphatemia in hemodialysis patients: The Calcium Acetate Renagel Evaluation (CARE Study)

BACKGROUND

Hyperphosphatemia underlies development of hyperparathyroidism, osteodystrophy, extraosseous calcification, and is associated with increased mortality in hemodialysis patients.

METHODS

To determine whether calcium acetate or sevelamer hydrochloride best achieves recently recommended treatment goals of phosphorus </=5.5 mg/dL and Ca x P product </=55 mg(2)/dL(2), we conducted an 8-week randomized, double-blind study in 100 hemodialysis patients.

RESULTS

Comparisons of time-averaged concentrations (weeks 1 to 8) demonstrated that calcium acetate recipients had lower serum phosphorus (1.08 mg/dL difference, P= 0.0006), higher serum calcium (0.63 mg/dL difference, P < 0.0001), and lower Ca x P (6.1 mg(2)/dL(2) difference, P= 0.022) than sevelamer recipients. At each week, calcium acetate recipients were 20% to 24% more likely to attain goal phosphorus [odds ratio (OR) 2.37, 95% CI 1.28-4.37, P= 0.0058], and 15% to 20% more likely to attain goal Ca x P (OR 2.16, 95% CI 1.20-3.86, P= 0.0097). Transient hypercalcemia occurred in 8 of 48 (16.7%) calcium acetate recipients, all of whom received concomitant intravenous vitamin D. By regression analysis hypercalcemia was more likely with calcium acetate (OR 6.1, 95% CI 2.8-13.3, P < 0.0001). Week 8 intact PTH levels were not significantly different. Serum bicarbonate levels were significantly lower with sevelamer hydrochloride treatment (P < 0.0001).

CONCLUSION

Calcium acetate controls serum phosphorus and calcium-phosphate product more effectively than sevelamer hydrochloride. Cost-benefit analysis indicates that in the absence of hypercalcemia, calcium acetate should remain the treatment of choice for hyperphosphatemia in hemodialysis patients.

A matched-pair, randomized study evaluating the efficacy and safety of Acticoat silver-coated dressing for the treatment of burn wounds

A new silver-coating technology was developed to prevent wound adhesion, limit nosocomial infection, control bacterial growth, and facilitate burn wound care through a silver-coated dressing material. For the purposes of this article, Acticoat (Westaim Biomedical Inc, Fort Saskatchawan, Alberta, Canada) silver-coated dressing was used. After in vitro and in vivo studies, a randomized, prospective clinical study was performed to assess the efficacy and ease of use of Acticoat dressing as compared with the efficacy and ease of our institution's standard burn wound care. Thirty burn patients with symmetric wounds were randomized to be treated with either 0.5% silver nitrate solution or Acticoat silver-coated dressing. The dressing was evaluated on the basis of overall patient comfort, ease of use for the wound care provider, and level of antimicrobial effectiveness. Wound pain was rated by the patient using a visual analog scale during dressing removal, application, and 2 hours after application. Ease of use was rated by the nurse providing wound care. Antimicrobial effectiveness was evaluated by quantitative burn wound biopsies performed before and at the end of treatment. Patients found dressing removal less painful with Acticoat than with silver nitrate, but they found the pain to be comparable during application and 2 hours after application. According to the nurses, there was no statistically significant difference in the ease of use. The frequency of burn wound sepsis (> 10(5) organisms per gram of tissue) was less in Acticoat-treated wounds than in those treated with silver nitrate (5 vs 16). Secondary bacteremias arising from infected burn wounds were also less frequent with Acticoat than with silver nitrate-treated wounds (1 vs 5). Acticoat dressing offers a new form of dressing for the burn wound, but it requires further investigation with greater numbers of patients in a larger number of centers and in different phases of burn wound care.

Relationship of femoral head and acetabular size to the prevalence of dislocation

Two clinical studies, one prospective randomized and one retrospective, were performed to evaluate the relationship of femoral head size and acetabular component outer diameter to the prevalence of dislocation of the modular total hip replacement. Between October 1995 and April 1996, 31 primary total hip arthroplasties in 30 patients were randomized to a femoral head diameter of 22 mm or 28 mm, for two groups of acetabular components of outer diameters of 56 mm or larger and 54 mm or smaller. Head size (22 mm) and acetabular component outer diameter (> or = 56 mm) were found to increase the risk of dislocation. From December 1984 to January 1994, 308 primary total hip arthroplasties were performed through a posterior approach by one surgeon using a modular 28 mm femoral head and one type of uncemented acetabular component. The rate of dislocation for acetabular components with an outer diameter of 62 mm or larger was increased significantly (five of 36 hips, 14%) compared with those with an outer diameter of 60 mm or smaller (11 of 272 hips, 4%).

Vascular calcification in patients with end-stage renal disease

Vascular calcification is the most common type of extra-osseous calcification in end-stage renal disease (ESRD), manifesting as both medial and intimal calcification of large arteries. It is highly prevalent, often progressive and is associated with reduced arterial elasticity and increased mortality. Risk factors for calcification in ESRD include age, duration of dialysis, diabetes mellitus, most probably an elevated calcium-phosphorus product (Ca x P) level, the dose of calcium-containing phosphate binders and the induction of the systemic inflammatory response. Uraemic calcification was thought to be a largely physico-chemical process facilitated by elevated Ca x P (i.e. "metastatic" calcification). It is now well established, however, that vascular smooth muscle cells actively take up phosphate to form bioapatite. This process is associated with a phenotypic transformation of vascular smooth muscle cells during which they express osteoblast markers. In addition to phosphate, various other factors are likely to increase bioapatite formation, e.g. lipids and inflammatory cytokines. There have also been relatively new insights relating to the role of endogenous inhibitors of calcification [i.e. matrix Gla protein and fetuin-A (alpha(2)-Heremans-Schmid glycoprotein)], in particular the downregulation of fetuin-A in systemic inflammation. Decreased serum fetuin-A has been shown to be associated with a reduced capacity to inhibit calcium phosphate precipitation in vitro and is predictive of mortality in dialysis patients. These new insights into pathogenesis may lead to better prevention and treatment of calcification (e.g. with calcimimetics, anti-cytokines, etc.). However, the only preventive approach to have been established prospectively to date is the replacement of calcium-containing phosphate binders with sevelamer HCl, a non-calcaemic phosphate binder. Yet, it remains unclear whether sevelamer HCl reduces vascular calcification by preventing episodes of hypercalcaemia and/or by reducing low-density lipoprotein (LDL)-cholesterol levels.

Two year comparison of sevelamer and calcium carbonate effects on cardiovascular calcification and bone density

BACKGROUND

Calcium-based phosphate binders may induce tissue calcification, and little is known about their effects on bone density. We compared the effects of a calcium with a non-calcium phosphate binder on both arterial calcification and bone density measured by computed tomography.

METHODS

Seventy-two adult haemodialysis patients were randomized to treatment with calcium carbonate (CC) or sevelamer (SEV) for 2 years. Electron beam CT scans were performed at baseline and at 6, 12 and 24 months. Serum phosphorus, calcium, calcium x phosphorus product and intact parathyroid hormone (iPTH) were measured and other routine laboratory tests were also carried out.

RESULTS

The average calcium x phosphorus product was similar in the two treatment groups. However, patients receiving CC had significantly lower average iPTH (P<0.01), were more likely to have hypercalcaemic episodes (P = 0.03) and had significantly greater increases in coronary artery (CC median 484, P<0.0001, SEV median 37, P = 0.3118, between-group P = 0.0178) and aortic (CC median 610, P = 0.0003, SEV median 0, P = 0.5966, between-group P = 0.0039) calcification scores. The CC group also had a significant decrease in trabecular bone density (CC median -6%, P = 0.0049, SEV median +3%, P = 0.0296, between-group P = 0.0025). However, there was no significant difference in cortical bone density between the two groups.

CONCLUSIONS

This 2 year study shows that calcium carbonate use is continuously associated with progressive arterial calcification in haemodialysis patients. In addition, it suggests that it is also associated with decreased trabecular bone density. However, this latter finding requires confirmation by a study specifically devoted to this issue.

Long-term comparison of a calcium-free phosphate binder and calcium carbonate--phosphorus metabolism and cardiovascular calcification

BACKGROUND

Calcium carbonate used as a phosphate binder may contribute to cardiovascular calcification. Long-term comparisons of sevelamer, a non-calcium polymeric phosphate binder, and calcium carbonate (CC) are lacking.

METHODS

114 adult hemodialysis patients were randomly assigned to open label sevelamer or CC for 52 weeks. Study efficacy endpoints included changes in serum phosphorus, calcium, calcium-phosphorus product, and lipids. In addition, initial and sequential electron beam computerized tomography scans were performed to assess cardiovascular calcification status and change during follow-up. Safety endpoints were serum biochemistry, blood cell counts and adverse events.

RESULTS

Patients receiving sevelamer had a similar reduction in serum phosphorus as patients receiving CC (sevelamer -0.58 +/- 0.68 mmol/l, CC -0.52 +/- 0.50 mmol/l; p = 0.62). Reductions in calcium-phosphorus product were not significantly different (sevelamer -1.4 +/- 1.7 mmol2/l2, CC -0.9 +/- 1.2 mmol2/l2; p = 0.12). CC produced significantly more hypercalcemia (> 2.8 mmol/l in 0% sevelamer and 19% CC patients, p < 0.01) and suppressed intact parathyroid hormone below 150 pg/ml in the majority of patients. Sevelamer patients experienced significant (p < 0.01) reductions in total (-1.2 +/- 0.9 mmol/l, -24%) and LDL cholesterol (-1.2 +/- 0.9 mmol/l, -30%). CC patients had significant increases in coronary artery (median +34%, p < 0.01) and aortic calcification (median +32%, p < 0.01) that were not observed in sevelamer-treated patients. Patients on sevelamer required more grams of binder (sevelamer 5.9 g vs. CC 3.9 g) and experienced more dyspepsia than patients on calcium carbonate.

CONCLUSIONS

Sevelamer is an effective phosphate binder that unlike calcium carbonate is not associated with progressive cardiovascular calcification in hemodialysis patients.

Short-term in vivo wear of cross-linked polyethylene

BACKGROUND

Cross-linked polyethylene was developed to reduce volumetric wear in prosthetic joints. Hip simulator studies have shown promising results with regard to wear reduction. This study evaluated the short-term in vivo wear of a moderately cross-linked polyethylene.

METHODS

Linear head penetration, as an assessment of in vivo polyethylene wear, was measured in two groups of patients after total hip replacement. Twenty-four hips received a conventional polyethylene insert and thirty-four, a cross-linked polyethylene liner; both inserts were manufactured by the same company. Linear and volumetric wear rates were measured on radiographs with use of a validated computer-assisted technique and were adjusted for patient-related factors. Patient activity was assessed by a computerized two-dimensional accelerometer worn on the ankle.

RESULTS

Patients with a conventional polyethylene insert showed a mean linear wear rate of 0.13 mm per year and a mean volumetric wear rate of 87.6 mm(3) per year. The group with a cross-linked polyethylene liner showed a mean linear wear rate of 0.02 mm per year and a mean volumetric wear rate of 17.0 mm(3) per year. Wear in the group with cross-linked polyethylene was 81% lower than that in the group with conventional polyethylene (p < 0.00001). Accounting for differences in patient activity, the adjusted wear rates per million cycles for a patient weight of 70 kg were 53 mm(3) per million cycles for conventional polyethylene and 15 mm(3) per million cycles for cross-linked polyethylene, a 72% reduction (p = 0.0002). No factor, other than the type of polyethylene, was found to influence the difference in wear rates between the two groups.

CONCLUSIONS

The results of this study are promising. The in vivo wear reduction with this cross-linked polyethylene is consistent with the predictions of hip simulator studies.

Third-body wear of highly cross-linked polyethylene in a hip simulator

The wear performance of a radiation cross-linked melted ultrahigh-molecular-weight polyethylene (UHMWPE) articulating against 28-mm cobalt chrome femoral heads in the presence of third-body particulate debris was investigated in a hip simulator and compared with the wear of conventional UHMWPE. Particles of aluminum oxide or bone cement containing barium sulfate were added to the serum. In the presence of aluminum oxide particles, the incremental wear rates of conventional UHMWPE averaged as high as 149 +/- 116 mg/million cycles compared with 37 +/- 38 mg/million cycles for the highly cross-linked components. The difference in the average weight loss was statistically significant at P <.01. With bone cement particles, the conventional UHMWPE components had an average incremental wear rate of 19 +/- 5mg/million cycles, and the wear rate of the highly cross-linked UHMWPE components was 0.5 +/- 0.7 mg/million cycles.

A randomized comparative trial between Acticoat and SD-Ag in the treatment of residual burn wounds, including safety analysis

OBJECTIVE

To investigate and evaluate the clinical efficacy and safety of Acticoat with nanocrystalline silver for external use on the management of the residual wounds post-burn.

METHODS

One hundred and sixty-six wounds of 98 burn patients were enrolled and divided into Acticoat group and silver sulfadiazine group in the multi-center randomized clinical trial. Acticoat was used as the treated group for those who have redness, swelling, and excessive secretion ("heavy" exudates) in the wound, Acticoat was changed once a day. When there is not much secretion in the wound, or redness and swelling were not obvious, the dressings were changed once every 3 days. Silver sulfadiazine (SD-Ag) was used as control group, which was treated under the usual clinical routine. Healing time was observed up to 20 days. Healing percentage on the 15th day after treatment was determined.

RESULTS

Healing time was 12.42+/-5.40 days after the application of Acticoat. This was significantly shorter than that of control wounds. The wounds of the trial group healed nearly 3.35 days earlier than the control ones. Healing percentage at 15 days in the trial wounds was 97.37%, which was higher than the control, but there was no significant difference between them. The bacterial clearance rate of the Acticoat group on the 6th and 12th day post-treatment was 16.67 and 26.67%, respectively, which was significantly higher than the control.

CONCLUSIONS

Acticoat with nanocrystalline silver promotes the healing process of residual wounds post-burn effectively. No adverse reaction of Acticoat was found during the study.

Bacteriology, inflammation, and healing: a study of nanocrystalline silver dressings in chronic venous leg ulcers

BACKGROUND

Healing of venous leg ulcers (VLUs) is often stalled despite compression therapy. Increased bacterial burden and chronic inflammation are 2 factors that may prevent these chronic VLUs (CVLUs) from healing. There is evidence that nanocrystalline silver dressings may reduce bacterial levels, decrease the chronic inflammatory response, and thus promote wound healing.

OBJECTIVE

To determine the effects of a nanocrystalline silver barrier dressing on wound microflora, wound inflammation, and healing in CVLUs.

METHOD

Stalled VLUs in 15 patients were managed using nanocrystalline silver dressings under 4-layer compression bandages. Paired skin biopsies at baseline and at an average of study week 6.5 were analyzed for bacteria and inflammatory infiltrates. Serum silver levels were monitored, and wound healing was assessed using planimetry.

RESULTS

VLUs in 4 patients healed, and 8 other patients completed the 12-week study. There was a significant reduction in the log10 total bacterial count between baseline and final biopsies (P = .011). Greater numbers of lymphocytes were associated with an increased reduction of ulcer size at week 6.5 and final assessment at week 12 (P < .05). Heavy neutrophilic infiltration in skin biopsies at week 6.5 was associated with high bacterial counts and delayed healing (P = .037). The median reduction in ulcer surface area for all patients was 83.5%. Serum silver levels increased slightly, but values were within the normal range.

CONCLUSION

A nanocrystalline silver dressing combined with 4-layer bandaging was safe and successful in promoting healing in stalled CVLUs. Healing was associated with a reduction in wound bacteria and neutrophilic inflammation with an associated persistent or high lymphocyte count, as determined by wound biopsy.

Use of porous high-density polyethylene in revision rhinoplasty and in the platyrrhine nose

Nasal reconstruction presents a significant challenge to the facial plastic surgeon. Reestablishment of the desired aesthetic nasal contour and restoration of respiratory function are the dual goals of this endeavor. While autologous cartilage or bone is considered optimal grafting material, the supply is often limited and harvesting entails additional morbidity. Many synthetic materials have been introduced for use in nasal reconstruction, but high infection and extrusion rates have left most surgeons dissatisfied with conventional implants. Porous polyethylene (Medpor) implants were used for nasal reconstruction in 187 patients; 66 (35.3%) patients underwent primary rhinoplasty, while revision surgery was performed in 121 (64.7%) patients. Most patients required multiple implants, including columella struts, plumper grafts, dorsal tip implants, and nasal valve battens. Postoperative follow-up ranged from 6 months to 3.5 years. Complications occurred in five (2.6%) patients. Three early and two delayed infections necessitated implant removal in five patients, all of whom had compromised skin-soft tissue envelopes secondary to heavy smoking, cocaine abuse, or prior surgery. One case of an overly augmented nasal dorsum and tip required implant removal, reduction, and reinsertion. All implants were easily removed. No other complications including implant extrusion or skin erosion have been noted. Porous polyethylene (Medpor) implants allow for fibrovascular ingrowth, which lends stability to the implant. Porous polyethylene implants are well tolerated and provide an ideal material for nasal reconstruction.

Seven years' experience with Integra as a reconstructive tool

The bilayered dermal substitute Integra (Integra Life Sciences Corp., Plainsboro, NJ) was developed and has been widely used as primary coverage for excised acute burns. Our take has been slightly different, finding it most useful in the management of complex soft-tissue loss and threatened extremities as the result of tendon, joint, or bone exposure. Often tasked to fill significant volume loss, we have become adept at stacked multiple-layer applications. Creative use of this material has resulted in unexpected successes with distal limb salvage; the technique takes its place beside adjacent tissue transfer, composite flaps, and vascular pedicle flaps in our burn reconstructive practice. A prospective registry (44 patients) has been kept during the past 7 years that catalogs wounds with complex soft-tissue loss treated with Integra grafts. Many of these patients were at risk of extremity loss because of exposed tendons, joints, or bone. Integra was applied after 1:1 meshing. With profound soft-tissue defects, multiple layers of Integra were serially applied 1 to 2 weeks apart for reconstitution of soft-tissue contours. Local Integra graft infections were managed by silicone unroofing followed by topical sulfamylon liquid dressings. Wounds addressed included fourth-degree burns, necrotizing fasciitis, pit-viper envenomations, and total abdominal wall avulsion in one patient after being run over by a bus. Patients generally were free of pain from their wounds during the maturation phase of the Integra neodermis. Restoration of tissue contour was significantly better when using multiple layers for deep defects. Second and third layers of Integra were successfully applied after an abbreviated first graft maturation period of 7 days. Epithelial autografts on multilayer Integra applications frequently "ghosted"; they would auto-digest to dispersed cells followed subsequently by the reappearance of a confluent epithelial layer. Final grafted skin morphology over palmar and plantar surfaces assumed the type and fingerprint pattern of the original tissues. Infections were readily visible. Early recognition kept them to easily treated circumscribed areas, which did not jeopardize the entire wound. Lengths of stay were long (range, 2-246 days) but not significantly greater than with traditional techniques. The specific reconstructive use of Integra permitted unexpected salvage of several threatened extremities by protecting exposed tendons, bones and joints. Long-term histologic examination revealed unexpected persistence of Integra collagen. Large volume loss wounds benefited from the ability to fill voids with multilayered applications.

Supragingival calculus: formation and control

Dental calculus is composed of inorganic components and organic matrix. Brushite, dicalcium phosphate dihydrate, octacalcium phosphate, hydroxyapatite, and whitlockite form the mineral part of dental calculus. Salivary proteins selectively adsorb on the tooth surface to form an acquired pellicle. It is followed by the adherence of various oral micro-organisms. Fimbriae, flagella, and some other surface proteins are essential for microbial adherence. Microbial co-aggregation and co-adhesion enable some micro-organisms, which are incapable of adhering, to adhere to the pellicle-coated tooth surface. Once organisms attach to the tooth surface, new genes could be expressed so that mature dental plaque can form and biofilm bacteria assume increased resistance to antimicrobial agents. Supersaturation of saliva and plaque fluid with respect to calcium phosphates is the driving force for plaque mineralization. Both salivary flow rate and plaque pH appear to influence the saturation degree of calcium phosphates. Acidic phospholipids and specific proteolipids present in cell membranes play a key role in microbial mineralization. The roles of crystal growth inhibitors, promoters, and organic acids in calculus formation are discussed. Application of biofilm culture systems in plaque mineralization is concisely reviewed. Anti-calculus agents used--centering on triclosan plus polyvinyl methyl ether/maleic acid copolymer, pyrophosphate plus polyvinyl methyl ether/maleic acid copolymer, and zinc ion-in commercial dentifrices are also discussed in this paper.

The rate of re-epithelialization across meshed skin grafts is increased with exposure to silver

The objective in this study was to determine whether exposure to pure silver increases the rate of re-epithelialization across a partial thickness wound. A meshed skin graft, placed on an excised burn wound was used as a healing model.

METHODS

The rate of meshed skin graft epithelial closure on an exposed burn using a moist healing environment was shown. A moistened silver delivery system (Acticoat) was compared with a standard xeroform and eight ply gauze dressing continually moistened with a 0.01% neomycin and polymyxin solution (NP). Twenty burn patients with deep burns of over 15% of TBS were excised and grafted with 2:1 meshed grafts. One graft area was treated with the antibiotic solution and another with the silver delivery. The meshed graft was performed within 3 days of injury.

RESULTS

No infections were noted and quantitative swab cultures gave less than 10(2) bacteria in all cases at wound closure. At day 7, re-epithelialization was complete with silver and 55% closed with NP solution. Wound closure was complete in the NP solution group at day 10. Silver increased re-epithelialization rate by over 40%, a significant increase. Graft take was over 95% in both groups.

CONCLUSION

Silver released in a moist wound surface environment significantly increases the rate of re-epithelialization compared to a standard antibiotic solution.

Mesh plug repair and groin hernia surgery

Since the mid-1980s, dramatic progress has been made in the evolution of hernia surgery, highlighted by the increasing use of prosthetic mesh. Among the mesh-based "tension-free" hernioplasties, the use of mesh plugs has garnered a large number of spirited enthusiasts, and plug herniorrhaphy has become the fastest growing hernia repair currently employed by the American surgeon. To demonstrate the simplicity and effectiveness of mesh plugs, a 9-year experience with almost 3300 patients is reported. Technical details are discussed and presentation of a literature search serves to further emphasize the utilitarian nature of this elegantly unsophisticated surgical operation.

Comparison of silver-coated dressing (Acticoat), chlorhexidine acetate 0.5% (Bactigrass), and fusidic acid 2% (Fucidin) for topical antibacterial effect in methicillin-resistant Staphylococci-contaminated, full-skin thickness rat burn wounds

Acticoat, chlorhexidine acetate 0.5%, and fusidic acid 2% were compared to assess the antibacterial effect of an application on experimental 15% BSA, full-thickness burn wounds in rats swabbed 24 h earlier with a 10(8) standard strain of methicillin-resistant Staphylococci. The swabbed organism was recovered from the eschar of all groups except the fusidic acid group. While there were significant differences between treatment groups and control group, the mean eschar concentrations did not differ significantly between the Acticoat and chlorhexidine acetate groups, but there were significant differences between the fusidic acid group and the other treatment groups. There were no statistically significant differences between treatment groups, and between control group and the chlorhexidine acetate group regarding recovery of the seeded organism from muscle, but there were significant differences between the control group and Acticoat group, and between control the group and the fusidic acid group. While no systemic spread was seen in the treatment groups, it was seen in six animals in the control group. The animal data suggest that fusidic acid is the most effective agent in the treatment of methicillin-resistant Staphylococcus aureus-contaminated burn wounds, and Acticoat is a choice of treatment with the particular advantage of limiting the frequency of replacement of the dressing.

Effects of sevelamer and calcium-based phosphate binders on uric acid concentrations in patients undergoing hemodialysis: a randomized clinical trial

OBJECTIVE

Gout affects a large fraction of persons with advanced chronic kidney disease, and hyperuricemia may increase the risk of cardiovascular disease. Several hypouricemic agents are contraindicated in patients with end-stage renal disease. Sevelamer is a nonabsorbed hydrogel that binds phosphorus and bile acids in the intestinal tract. Results of short-term and open-label studies suggest that sevelamer might lower the concentration of uric acid, another organic anion. We undertook this study to test our hypothesis that the reduction in serum uric acid concentration induced by sevelamer would be confirmed in a long-term, randomized, clinical trial comparing sevelamer with calcium-based phosphate binders.

METHODS

Two hundred subjects undergoing maintenance hemodialysis were randomly assigned to receive either sevelamer or calcium-based phosphorus binders in an international, multicenter, clinical trial. Data on baseline and end-of-study uric acid concentrations were available in 169 subjects (85%); the change in uric acid concentration from baseline to the end of the study was the outcome of interest.

RESULTS

Baseline clinical characteristics, including mean uric acid concentrations, were similar in subjects randomly assigned to receive sevelamer and calcium-based phosphate binders. The mean change in uric acid concentration (from baseline to the end of the study) was significantly larger in sevelamer-treated subjects (-0.64 mg/dl versus -0.26 mg/dl; P = 0.03). The adjusted mean change in uric acid concentration was more pronounced when the effects of age, sex, diabetes, vintage (time since initiation of dialysis), dialysis dose, and changes in blood urea nitrogen and bicarbonate concentrations were considered (-0.72 mg/dl versus -0.15 mg/dl; P = 0.001). Twenty-three percent of sevelamer-treated subjects experienced a study-related reduction in the concentration of uric acid equal to -1.5 mg/dl or more, compared with 10% of calcium-treated subjects (P = 0.02).

CONCLUSION

In a randomized clinical trial comparing sevelamer and calcium-based phosphate binders, treatment with sevelamer was associated with a significant reduction in serum uric acid concentrations.

Boron and Poloxamer (F68 and F127) Containing Hydrogel Formulation for Burn Wound Healing

Burn injuries, the most common and destructive forms of wounds, are generally accompanied with life-threatening infections, inflammation, reduced angiogenesis, inadequate extracellular matrix production, and lack of growth factor stimulation. In the current study, a new antimicrobial carbopol-based hydrogel formulated with boron and pluronic block copolymers was evaluated for its healing activity using in vitro cell culture techniques and an experimental burn model. Cell viability, gene expression, and wound healing assays showed that gel formulation increased wound healing potential. In vitro tube-like structure formation and histopathological examinations revealed that gel not only increased wound closure by fibroblastic cell activity, but also induced vascularization process. Moreover, gel formulation exerted remarkable antimicrobial effects against bacteria, yeast, and fungi. Migration, angiogenesis, and contraction-related protein expressions including collagen, α-smooth muscle actin, transforming growth factor-β1, vimentin, and vascular endothelial growth factor were considerably enhanced in gel-treated groups. Macrophage-specific antigen showed an oscillating expression at the burn wounds, indicating the role of initial macrophage migration to the wound site and reduced inflammation phase. This is the first study indicating that boron containing hydrogel is able to heal burn wounds effectively. The formulation promoted burn wound healing via complex mechanisms including stimulation of cell migration, growth factor expression, inflammatory response, and vascularization.

Sevelamer hydrochloride with or without alphacalcidol or higher dialysate calcium vs calcium carbonate in dialysis patients: an open-label, randomized study

BACKGROUND

Sevelamer hydrochloride was recently proposed as a phosphate binder to prevent hypercalcaemia in place of calcium alkaline salts in dialysis patients. So far, it has been evaluated only in patients receiving calcitriol, without comparison with CaCO(3) alone, although the latter was found to be as effective as the combination of calcitriol and Al(OH)(3) in suppressing parathyroid hormone (PTH) without inducing hypercalcaemia and to have a better lowering effect on serum phosphate. Moreover, this bile salt binder may decrease serum 25-OH vitamin D. Therefore, we compared for 5 months two strategies for controlling moderate hyperparathyroidism: CaCO(3) alone vs sevelamer in conjunction with measures to increase calcium balance.

METHODS

Forty-two patients were randomized: 21 continued their treatment with 4.8 g/day CaCO(3) and 21 were switched to sevelamer (initial dose: 2.4 g/day, increased to 4.4 g/day). Each month, when serum-corrected calcium decreased below 2.30 mmol/l, dialysate calcium was increased or alphacalcidol was given at each dialysis session, according to serum PO(4) levels. The following parameters were monitored: serum Ca, PO(4), bicarbonate and protein, weekly; and serum PTH, 25-OH vitamin D and total, LDL and HDL cholesterol monthly.

RESULTS

Except for higher serum phosphate at month 1, lower serum bicarbonate at month 2 and lower LDL cholesterol at month 5 in the sevelamer group, no difference was found between the two groups. Compared with baseline levels, PTH increased and 25-OH vitamin D decreased significantly in both groups, these two parameters being inversely correlated.

CONCLUSIONS

Given comparable control of plasma calcium, phosphate and 25-OH vitamin D, PTH control is comparable in both strategies. Sevelamer does not induce greater vitamin D depletion than CaCO(3). The transient decrease of serum bicarbonate after discontinuation of CaCO(3) in the sevelamer group suggests a less optimal prevention of acidosis. The sevelamer-induced decrease in LDL cholesterol gives this drug a potential advantage in cardiovascular prevention.