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At least 451 records · Page 25Linked to original sources
PubMed2004

Biocompatibility and biodegradation of cross-linked gelatin/hyaluronic acid sponge in rat subcutaneous tissue.

A gelatin/hyaluronic acid (GH) sponge has been fabricated by freeze-drying and cross-linking. The GH sponge was insoluble when cross-linked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. The morphologies of sponges were investigated using a field emission scanning electron microscope. The porosity of the GH sponge increased with hyaluronic acid content. The GH sponge was biodegradable, as evidenced by implantation in Wistar rat subcutaneous connective tissue. Fibroblasts infiltrated into the sponge matrix, and regenerated collagen in the matrix to a level of 25% by 15 days after surgery. The GH73 sponge induced an acute inflammatory response compared with the GH91 sponge. This inflammatory response could have been stimulated by the presence of hyaluronic acid up to Day 10, as it decreased afterwards. The C-reactive protein of blood samples also indicated the same result. The blood tests and histological results show that GH sponges have good biocompatibility and low antigenicity for tissue engineering scaffolds.

Animals↗
PubMed2002

Glucose gradient differences in subcutaneous tissue of healthy volunteers assessed with ultraslow microdialysis and a nanolitre glucose sensor.

The abdominal subcutaneous interstitium is easily accessible for monitoring glucose for Diabetes Mellitus research and management. The available glucose sensing devices demand frequent blood sampling by finger pricking for calibration. Moreover, there is controversy about the exact relationship between the levels of glucose in the subcutis and blood. In the present study ultra-slow microdialysis was applied for subcutaneous fluid sampling, allowing continuous measurement of glucose in an equilibrated fluid using a nanolitre size sensor. The present method avoids in vivo calibration. During an oral glucose tolerance test glucose levels were measured simultaneously in blood, in adipose tissue and loose connective tissue layers of the abdominal subcutis in seven healthy subjects. Fasting glucose levels (mM) were 2.52 +/- 0.77 in adipose tissue and 4.67 +/- 0.17 in blood, this difference increasing to 6.40 +/- 1.57 and 11.59 +/- 1.52 at maximal glucose concentration. Moreover, the kinetics of glucose in blood and adipose tissue were different. In contrast, connective tissue glucose levels differed insignificantly (4.71 +/- 0.21 fasting and 11.70 +/- 1.96 at maximum) from those in blood and correlated well (r2 = 0.962). Ultra-slow microdialysis combined with a nanolitre glucose sensor could be of benefit to patients in intensive diabetes therapy. Frequent blood sampling for in vivo calibration can be avoided by monitoring glucose in the abdominal subcutaneous loose connective tissue, rather than in the adipose tissue.

Adipose Tissue↗
PubMed1998

Effect of physicochemical variables of regular insulin formulations on their absorption from the subcutaneous tissue.

BACKGROUND: Physicochemical properties of regular insulin formulations influence the subcutaneous absorption kinetics. AIM OF STUDY: To compare the subcutaneous absorption of regular insulin formulations with different concentration, temperature and hexamer-aggregation. STUDY DESIGN: In random order, 24 fasting healthy men were injected with identical doses of regular human insulin in concentrations of 40 units/ml (U40), 100 units/ml (U100), and the insulin analogue Lispro; regular human insulin U100 was applied at either 8, or 37 degrees C. Insulinaemia, C-peptide and plasma glucose levels were monitored for every 15 min up to 45 min after the injection. RESULTS: In comparison to U100 human regular insulin, Lispro induced significantly higher insulinaemia 15-45 min after injection. In comparison to U40 insulin, however, insulinaemia was higher only at 15 and 30 min after injection, and was comparable at 45 min (210 +/- 11 pmol/l after Lispro versus 191 +/- 15 pmol/l after U40 regular insulin; P > 0.06). There was no difference in insulinaemia between U100 regular insulin of 8 or 37 degrees C. C-peptide and plasma glucose levels were altered accordingly. CONCLUSION: Assuming identical clearance rates of human insulin and Lispro, our data show that insulin absorption is substantially increased by reduced hexamer-aggregation (e.g. with insulin analogue Lispro), when compared to U100 regular human insulin. It is only marginally better, when compared to U40 regular human insulin. The increase in insulin temperature from 8 to 37 degrees C had no effect on the respective absorption kinetics.

Adult↗
PubMed1989

The influence of thoracic epidural analgesia on transcapillary fluid balance in subcutaneous tissue. A study in patients undergoing aortocoronary bypass surgery.

Clinical observation and calculation of fluid balance have shown that patients undergoing aortocoronary bypass surgery with thoracic epidural analgesia (TEA) in addition to general anesthesia retain less fluid than patients having general anesthesia only. The present study was designed to investigate whether this effect could be explained by thoracic epidural analgesia influencing the transcapillary fluid balance, i.e. the transcapillary forces (COPpl, COPif, Pif). Interstitial fluid colloid osmotic pressure (COPif) and interstitial fluid pressure (Pif) were measured subcutaneously at heart level by the blister suction technique and the wick-in-needle technique, respectively. Simultaneously plasma colloid osmotic pressure (COPpl) was recorded. Sixteen male patients were allocated to two groups, one having general anesthesia only (controls, n = 8). The other group (TEA, n = 8) received, at the induction of anesthesia, bupivacaine 50 mg via an epidural catheter as an adjunct to general anesthesia. TEA was maintained by continuous infusion for 24 h postoperatively. Preoperatively no intergroup differences were observed in "the Starling forces" (COPpl, COPif, Pif). At the start of extracorporeal circulation COPpl was significantly lower in the TEA-group than in controls. During extracorporeal circulation the transcapillary COP-gradient (COPpl-COPif) was reversed in both groups. At the end of extracorporeal circulation Pif increased to a minor degree in the TEA-group and remained significantly lower than in controls from 3 to 24 h postoperatively. The subcutaneous interstitial tissue could be less expanded postoperatively in the TEA-group, also reflected by a lower increase in Pif.

Aged↗
PubMed1988

Therapeutic ratio of photodynamic therapy in the treatment of superficial tumours of skin and subcutaneous tissues in man.

Six patients with a total of 34 assessible subcutaneous or cutaneous lesions were treated with photodynamic therapy using 1.0, 1.5 or 2.0 mg kg-1 of photofrin II and 25-100 J cm-2 of red light (630 nm). The incidence of complete tumour response and skin necrosis were used to try to assess the therapeutic ratio of photodynamic therapy. The tumour response rate was 47%. The rate of tumour control and necrosis increased in parallel with dose of photosensitizer and light used, implying a low therapeutic ratio. However, the use of necrosis with eschar formation as an end-point for severe normal tissue damage is questioned as the skin healed completely in all cases and with minimal discomfort to the patients.

Dihematoporphyrin Ether↗
PubMed1987

[Roentgenography of the skin and subcutaneous tissue in postmastectomy edema of the upper extremities].

The results of radiography of the forearm and shoulder soft tissues in 47 patients with postmastectomy syndrome before and after conservative treatment and in 6 controls made it possible to determine differences in x-ray imaging of a skin and subcutaneous fat layer in limb edema. These differences were determined by lymph flow disorders and the formation of a connective tissue component in subcutaneous fat and could be used for objective assessment of a degree of edema, determination of tactics of rehabilitation activities and assessment of their effectiveness.

Adipose Tissue↗
PubMed1981

Local regulation of blood flow in subcutaneous tissue in patients with acute myocardial infarction.

1. Local regulation of subcutaneous blood flow in the forearm was studied in the acute phase of myocardial infarction. Blood flow was measured by the local 133Xe-washout technique. 2. Plasma concentrations of noradrenaline and adrenaline were increased on day 1, suggesting an increase in sympathetic neuronal activity, but gradually returned to normal thereafter. 3. Subcutaneous blood flow on day 1 was far below normal (38%) and steadily increased to reach normal at day 7 after coronary occlusion. The sympathetic vasoconstrictor activity that caused the initial reduction in flow could be blocked by proximal nervous blockade, increasing the subcutaneous blood flow by 130, 63 and 14% on days 1, 3 and 7 respectively after coronary occlusion. A normal response to decrease in arterial perfusion pressure was observed, suggesting that intrinsic vascular reactions responsible for autoregulation of blood flow were not affected by the increase in sympathetic vasoconstrictor activity. The vasoconstrictor response to increase in venous transmural pressure could not be demonstrated on day 1 after coronary occlusion but gradually reappeared during the following days. 4. Abolition of the vasoconstrictor response is most likely to be due to a centrally elicited increase in sympathetic activity, as a normal vasoconstrictor response was obtained after proximal nervous blockade. Thus the local sympathetic reflex mechanism underlying the vasoconstrictor response appears to be suppressed by a centrally elicited increase in sympathetic discharge rate.

Adult↗
PubMed2005

Biocompatibility of an electrochemical sensor for continuous glucose monitoring in subcutaneous tissue.

BACKGROUND: The continuous monitoring of glucose allows for tighter control of the glucose concentration and thus may prevent hyper- and hypoglycemia as well as long-term complications of diabetes. While most current systems depend on the transport of fluid to a glucose sensor outside the body, we investigate the possibility of implanting a reagent-based sensor directly into the skin. In this manuscript, the biocompatibility of an electrochemical sensor for continuous glucose monitoring was assessed in vitro and in vivo. METHODS: Cytotoxicity was investigated in vitro using agar diffusion testing. In vivo biocompatibility was assessed by means of histomorphological examination of the surrounding tissue 10 days after sensor implantation in rats. RESULTS: The grade of cytotoxicity of the individual sensor components in vitro was between none and mild based on agar diffusion testing. The complete sensor also showed no cytotoxic effects when coated with the co-polymer MPC (2-methacryloyloxyethyl phosphorylcholine, Lipidure CM 5206, NOF Corp., Tokyo, Japan) and when assessed under working conditions, i.e., when a bias voltage was applied to the sensor. Additionally, the hydrogen peroxide-which is inherently generated by the enzymatic glucose detection process using glucose oxidase (GOD)-is likely to have been sufficiently decomposed under these working conditions. Finally, no toxic leachable substances were found during the cytotoxicity testing of sensors and its extracts in vitro. In the in vivo experiments, the strongest foreign body reaction (FBR) was found near the GOD-electrode using a sensor without MPC coating and without a porous membrane. Covering the sensor with MPC, a porous membrane, or both led to a gradual decrease of the FBR down to the level of the negative control. CONCLUSIONS: The electrochemical, reagent-based sensor with MPC coating and/or a porous membrane is suitable for continuous monitoring of glucose from a biocompatibility standpoint.

Animals↗
PubMed2004

Subcutaneous tissue release of amikacin from a fibrin glue/polyurethane graft.

We investigated whether fibrin glue (FG) might be useful as a carrier of amikacin (AMK) for prevention of local graft infection. After AMK (4.0 mg)-treated FG (AMK-FG) polyurethane grafts were implanted subcutaneously in the anterior abdominal region of Sprague-Dawley rats, AMK concentrations in tissues surrounding the implantation sites were compared over time with concentrations at the same sites in rats given an intravenous injection of AMK (4.0 mg). In the injection group, AMK concentrations in serum were detectable only for 4 h, whereas AMK released from AMK-FG grafts remained detectable over 24 h. Until 4 h after implantation, AMK concentrations in tissues near implantation sites were significantly higher in the AMK-FG graft group than in the injection group; peak local concentrations during that time were 210 times higher for the AMK-FG graft group than for the injection group. Areas under the tissue concentration-time curve (AUC) for AMK were 171 microg x h/g and 1.35 microg x h/g in the AMK-FG graft and injection groups, respectively. FG therefore was considered to control release of AMK and to maintain a high AMK concentration in tissues surrounding the implantation site. Thus, AMK-FG polyurethane graft delivery may be useful in preventing local infection by local delivery of AMK.

Abdomen↗
PubMed1975

Perforated viscus presenting with gas in the soft tissues (subcutaneous emphysema).

We have reviewed the spectrum of gaseous densities in the soft tissues secondary to a perforated viscus. All patients presented late and most were elderly. The most common surgical procedure was diversion of the fecal stream proximal to the perforation. In our series 4 of 7 patients died in the immediate postoperative period. Knowledge of the mechanism and differential diagnosis of this entity will prevent overlooking this possibility, as occurs too frequently, particularly with subcutaneous emphysema of the leg.

Abscess↗
PubMed1981

Leiomyosarcoma of the skin and subcutaneous tissue.

In a study of 65 primary cutaneous leiomyosarcomas and 15 primary superficial subcutaneous leiomyosarcomas, tumors occurred at any age but were more common in middle age and most common on the extremities. They developed as solitary painful or tender intracutaneous or subcutaneous nodules. Microscopically, the cutaneous leiomyosarcomas consist of a poorly delineated proliferation of spindle-shaped atypical myomatous cells arranged in interlacing fascicles which merge into collagenous stroma. Subcutaneous leiomyosarcomas are more sharply circumscribed and typically include a vascular pattern. About 40% of the cutaneous leiomyosarcomas recurred, but none metastasized despite a high mitotic frequency and marked cytologic atypia. Among the 12 patients with subcutaneous leiomyosarcomas, one-half of the tumors recurred and one-third eventuated in metastasis or tumor-related death. Cutaneous leiomyosarcomas have a relatively benign biologic course and may be excised conservatively, but are less likely to recur if the local excision is wide enough to require a skin graft for closure of the surgical defect. For primary subcutaneous leiomyosarcoma, early wide local excision with adequate clear histologic borders constitutes rational treatment.

Adolescent↗