Therapeutic value of intravenous heparin in microvascular surgery: an experimental vascular thrombosis study

In an attempt to decrease a 10 to 15 percent vascular thrombosis rate leading to graft occlusion, low-dose human-grade heparin was studied to determine if carefully monitored intravenous therapy would increase 7-day patency in a known potent thrombosis model. In New Zealand white rabbits, the type of infusate administered intravenously, either saline (30 animals) or heparin (35 animals), was selected at random after completing a 2-mm arterial inversion graft in the femoral artery. A 72-hour infusion was used in all animals; the control group received sterile saline and the experimental group received a heparin infusion at 45 microliters per hour after a 500-unit bolus. All grafts in both groups were patent at the time of groin closure. Patency in the heparin-perfused group was 67 percent (24 of 35) as compared to 19 percent (6 of 30) in the control group (p less than 0.05) 1 week postoperatively. Scanning electron microscopy showed significantly less dense fibrin deposition and a decrease in the number of aggregated platelets in the heparin-perfused grafts. Partial tissue thromboplastin time values in the experimental group ranged between 55 and 75 seconds (control 20 to 25 seconds). We have shown that heparin, an inexpensive and readily available agent, maintains 1-week microarterial patency and results in few complications in a reliable, reproducible, and versatile thrombosis model. The clinical ramifications of using an antiplatelet agent that diminishes fibrin deposition in microsurgery are apparent.     

Treatment options in extravasation injury: an experimental study in rats

Local skin necrosis after extravasation of doxorubicin hydrochloride (Adriamycin), a widely used chemotherapeutic agent, is a common problem in cancer patients. Even though several treatment options have been proposed for extravasation injury, there is still controversy regarding the management of such lesions. The aim of this study was to compare the efficacy of saline infiltration, vitamin C infiltration, suction technique, and early surgical excision as a treatment in a rat extravasation model. The authors planned their study in two stages. In stage 1, the lowest effective dose of doxorubicin at which a homogeneous skin necrosis was formed and the method of administration were investigated. Intradermal and subpannicular injections were made for six rats, using six different concentrations of doxorubicin (0.33, 0.5, 0.66, 1.0, 1.33, and 1.5 mg/ml). In stage 1, the intradermal injection produced homogeneous and uniform tissue necrosis. In stage 2, the efficacy of saline infiltration (group 1), vitamin C infiltration (group 2), suction (group 3), suction and saline washout (group 4), suction and vitamin C washout (group 5), and early surgical excision (group 6) was compared. The treatment options were applied 2 hours after doxorubicin injection. At the end of the seventh day, the presence and size of ulcers at the injection site were calculated. Fourteen days after injection, a histopathologic examination was performed for each treatment and control group. In groups 1 and 3, there was no statistically significant difference in the size of necrosis compared with the control groups. In groups 2, 4, and 5, the size of necrosis was smaller compared with the control groups, and this was statistically significant. Furthermore, in group 4 (suction and saline washout) and group 5 (suction and vitamin C washout), the calculated area of necrosis was smaller compared with other treatment groups, and this was statistically significant. The findings supported the assertion that suction and saline or vitamin C washout reduce necrotic tissue size in extravasation injury.     

RETRACTED ARTICLE: Histopathological and clinical evaluation of Kombucha tea and Nitrofurazone on cutaneous full-thickness wounds healing in rats: an experimental study

Background

Kombucha, a fermented tea (KT) is claimed to possess many beneficial properties. The aim of this study was to evaluate clinical and histopathological alterations of Kombucha tea and Nitrofurazone on cutaneous full-thickness wounds healing in rat.

Methods

In present study 24 Wister -albino rats weighing 150–200 g were selected and divided to two treatment groups as Nitrofurazone ointment (0.2%) and Kombucha tea. Subsequently, the anesthesia was exerted by Ketamin hydrochloride 10% (40 mg/kg) and Xylasine (2 mg/kg) through intra muscular (IM) route. Furthermore, upon preparation of dorsal region of the animal for surgery, a piece of full-thickness skin removed (2?×?2 cm). In order to comparing wounds healing clinically and histologically, once every four days from the commencement, the wounds were photographed and the healed surface was measured by Scion image software.

Result

The clinical findings indicated that the Kombucha fungus resulted in precipitating healing than Nitrofurazone; however, it was not significant (p?>?0.05). In order to pathological comparing of wound healing process, several wound biopsies were taken on 4, 8, 12, 16 and 20^th days. Additionally, the histopathological results demonstrated that there was inflammation in Nitrofurazone group through twelveth day, somehow the epithelium was formed and abundant vessels were visible. Although on 16^th day and the previous days the healing condition of Kombucha fungus was considered as minimal rate, revealing it is similar to Nitrofurazone group on 20^th day.

Conclusions

To wrap up. These observations suggest that the Kombucha fungus healing quality was rapid from 12^th day to the end of the research, whereas no significant difference was observed.

Virtual slide

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1107407136102196

     

Prefabrication of composite free flaps through staged microvascular transfer: an experimental and clinical study

The feasibility of prefabricating free flaps by inducing, through the process of staged reconstruction, an arteriovenous bundle and its surrounding fascia to perfuse a selected block of tissue was investigated experimentally and clinically. Sixteen rat knee joints were wrapped with their ipsilateral superficial inferior epigastric (SIE) fascia. In 8 joints, the composite flaps were resected en bloc and were immediately replaced orthotopically pedicled upon the superficial inferior epigastric vessels. In the remaining joints, the resection and orthotopic transfer were performed 2 weeks later. Only the joints in the latter group, which benefited from the staging period, were found to be perfused. The long finger proximal interphalangeal joint of a child was reconstructed by the staged microvascular transfer of his second toe proximal interphalangeal joint. At the first stage, a temporalis fascia flap was wrapped around the toe proximal interphalangeal joint and revascularized to the dorsalis pedis vessels. Six weeks later, the joint and its temporalis fascia envelope were dissected, and the "prefabricated" joint flap was transferred to the hand and revascularized to the wrist vessels. Bony union progressed uneventfully with excellent recovery of the range of motion. We conclude that regardless of the indigenous vascular anatomy, an unlimited array of composite free flaps can be constructed and transferred based on induced large vascular pedicles.     

The effect of pulsed electromagnetic fields on secondary skin wound healing: an experimental study

A variety of pulsed electromagnetic fields (PEMFs) have already been experimentally used, in an effort to promote wound healing. The aim of the present study was to investigate the effects of short duration PEMF on secondary healing of full thickness skin wounds in a rat model. Full thickness skin wounds, 2 by 2 cm, were surgically inflicted in two groups of male Wistar rats, 24 animals each. In the first group (experimental group - EG), the animals were placed and immobilized in a special constructed cage. Then the animals were exposed to a short duration PEMF for 20 min daily. In the second group (control group - CG), the animals were also placed and immobilized in the same cage for the same time, but not exposed to PEMF. On days 3, 6, 9, 12, 18, and 22, following the infliction of skin wounds, the size and healing progress of each wound were recorded and evaluated by means of planimetry and histological examination. According to our findings with the planimetry, there was a statistically significant acceleration of the healing rate for the first 9 days in EG, whereas a qualitative improvement of healing progress was identified by histological examination at all time points, compared to the control group.     

Investigating the two regimes of fibrin clot lysis: an experimental and computational approach

It has been observed in vitro that complete clot lysis is generally preceded by a slow phase of lysis during which the degradation seems to be inefficient. However, this slow regime was merely noticed, but not yet quantitatively discussed. In our experiments, we observed that the lysis ubiquitously occurred in two distinct regimes, a slow and a fast lysis regime. We quantified extensively the duration of these regimes for a wide spectrum of experimental conditions and found that on average, the slow regime lasts longer than the fast one, meaning that during most of the process, the lysis is ineffective. We proposed a computational model in which the properties of the binding of the proteins change during the lysis: first, the biochemical reactions take place at the surface of the fibrin fibers, then in the bulk, resulting in the observed fast lysis regime. This simple hypothesis appeared to be sufficient to reproduce with a great accuracy the lysis profiles obtained experimentally.     

Experimental microvascular anastomoses in radiated vessels: a study of the patency rate and the histopathology of healing.

A study of microvascular surgery in radiated tissue is presented. The radiation damage to the vessels and its consequence on the histopathology of blood vessel healing is discussed. The main difficulty encountered was the radiation-induced fibrosis in the perivascular tissues. The patency rate in ther arterial anastomoses was unaltered by prior radiation, but the patency rate in the venous anastomoses fell to 54 percent after high doses of prior radiation.     

Colonic healing after portal ischemia and reperfusion: an experimental study with oxidative stress biomarkers

Abstract

This experimental study aimed to evaluate colon healing after portal ischemia followed by reperfusion. Seventy male Wistar rats randomly distributed in four groups were used: Group 1, colonic anastomosis (n = 20); Group 2, portal ischemia-reperfusion (n = 20); Group 3, colonic anastomosis and portal ischemia-reperfusion (n = 20); and Group 4, control (n = 10). In the postoperative period, these rats were re-allocated into subgroups and lipid peroxidation and protein oxidation plasma levels were evaluated on days 1 and 5 by thiobarbituric acid reactive substances (TBARS) and slot-blotting assays, respectively. A segment of the right colon was also removed for collagen analysis. Both malondialdehyde (MDA) and protein carbonyl levels (oxidative markers of lipids and proteins) presented a significant increase after reperfusion in Group 3 on days 1 (P < 0.002) and 5 (P < 0.0001). In this same group, an extensive inflammatory process showing decreased fibroplasia was observed, with deficiency in collagen deposition on both sides of the anastomosis edges. Taken together, these results indicate that portal congestion followed by reperfusion induces an oxidative stress, which impaired the mechanism of colon anastomotic healing.     

Colonic healing after portal ischemia and reperfusion: an experimental study with oxidative stress biomarkers

This experimental study aimed to evaluate colon healing after portal ischemia followed by reperfusion. Seventy male Wistar rats randomly distributed in four groups were used: Group 1, colonic anastomosis (n = 20); Group 2, portal ischemia-reperfusion (n = 20); Group 3, colonic anastomosis and portal ischemia-reperfusion (n = 20); and Group 4, control (n = 10). In the postoperative period, these rats were re-allocated into subgroups and lipid peroxidation and protein oxidation plasma levels were evaluated on days 1 and 5 by thiobarbituric acid reactive substances (TBARS) and slot-blotting assays, respectively. A segment of the right colon was also removed for collagen analysis. Both malondialdehyde (MDA) and protein carbonyl levels (oxidative markers of lipids and proteins) presented a significant increase after reperfusion in Group 3 on days 1 (P < 0.002) and 5 (P < 0.0001). In this same group, an extensive inflammatory process showing decreased fibroplasia was observed, with deficiency in collagen deposition on both sides of the anastomosis edges. Taken together, these results indicate that portal congestion followed by reperfusion induces an oxidative stress, which impaired the mechanism of colon anastomotic healing.     

Preclinical testing of femoral hip components: an experimental investigation with four prostheses

Existing standards for the preclinical testing of femoral hip implants have been successful in the objective of guaranteeing the implant's fatigue strength. There is a need for an experimental test which could ensure prostheses were not susceptible to aseptic loosening. In this study we measure the relative movement between the prosthesis and the bone of four different cemented femoral component designs in in vitro tests. The aim is to determine if differences can be distinguished and whether the differences correlate with clinical performance. The four designs are the Charnley (DePuy International Ltd., UK), the Exeter (Stryker Osteonics Howmedica Corp., USA), the Lubinus SPII (Waldemar-Link GmbH, Germany), and the Miiller Curved (JRI Ltd, UK). Five tests were carried out for each femoral component type, giving a total of 20 tests, and their permanent relative displacement (termed migration) and recoverable (i.e., elastic) relative displacement (termed inducible displacement) monitored over one million loading cycles. Considerable variation occurred in the tests. Nonetheless, most femoral components migrated medially, posteriorly, and distally. Most also rotated into varus. Translations of the Charnley (64 microns) and Lubinus (67 microns) implants were less than the Müller (72 microns) and Exeter (94 microns) implants, but this difference is not statistically significant. Most of the femoral components had rapid early migration followed by slower steady-state migration. With regard to the steady state inducible displacements of the prostheses, those of the Charnley, Exeter, and Lubinus decreased or were stable with respect to time, whilst those of the Müller typically increased with respect to time. It is concluded that migration is not a suitable basis for in vitro comparison of prosthesis designs. However inducible displacement trends provide a clinically comparable performance ranking.     

Fetal wound healing: a biochemical study of scarless healing

Human fetal surgery is being successfully performed today in a small number of highly selected patients for conditions that may lead to irreversible damage to the fetus and threaten the viability of the newborn. Following surgical repair, fetal wounds heal without scarring. This study was initiated to characterize fetal wounds both histologically and biochemically. Gore-Tex tubing was implanted into the subcutaneous tissue of the back of fetal, newborn, and adult New Zealand white rabbits. Light microscopic examination of healed wounds revealed no evidence of scar formation. Electron microscopy demonstrated a striated fibrillar structure suggestive of collagen within the lumen of the Gore-Tex tubing implants. Amino acid analysis (sensitivity 40 pmol) confirmed the presence of hydroxylysine and hydroxyproline within the Gore-Tex wound chambers indicating the presence of collagen in fetal wounds. The small amount of collagen precluded the typing of the collagen using cyanogen bromide peptide analysis. The absence of scarring and the small amounts of detectable collagen suggest a high degree of reorganization of the connective tissues involved in repair. The fetal wound matrix is rich in hyaluronic acid. Topical hyaluronic acid has been associated experimentally with a reduced amount of scarring in postnatal wound healing. Hyaluronic acid extracted from human skin and scar tissue is associated with collagen and other proteins. We propose that a hyaluronic acid-collagen-protein complex may play a role in fetal wound healing.     

An absorbable catheter system for use in microvascular and peripheral vascular surgery: an experimental study in the canine.

An absorbable catheter for use in regional anticoagulation in microvascular and peripheral vascular surgery was studied in 20 sites in 10 adult beagle dogs to answer three questions: (1) Could the polyglycolic acid and trimethylene carbonate catheter withstand intraarterial pressures of infusion and completely absorb over a predictable time interval? (2) Could the catheter be filled with heparin and maintain patency for reuse after a 24-hour interval? (3) Could the catheter be placed in a side branch of a major artery and, after catheter dissolution, maintain long-term patency of the primary feeding artery? The catheters were completely absorbed from 24 to 34 weeks following implantation. The catheters were able to withstand intraarterial pressures, and no evidence of significant thrombosis of the primary feeding artery was seen in any animal studied. No complications of catheter leak, hematoma formation within the catheter placement sites, or sepsis were noted in any of the 20 catheter sites studied.