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Interstitial colloid osmotic and hydrostatic pressures in human subcutaneous tissue during early stages of heart failure.

Subcutaneous oedema is a common finding in heart failure. However, some patients have reduced cardiac pump function without oedema. The aim of this study was to investigate whether local mechanisms in subcutaneous tissue contribute to oedema prevention. A reduction in interstitial colloid osmotic pressure (pii) and a rise in interstitial fluid hydrostatic pressure (Pi) will both counteract a rise in capillary filtration caused by heart failure. Cardiac catheterization was done in 22 angina pectoris patients without visible oedema. Two days later pii was measured with a wick method and Pi was measured with a wick-in-needle method. Both parameters were measured in subcutaneous tissue on thorax at heart level and on the ankle. Plasma volume was determined by 125I-albumin and extracellular volume measured with 35SO4. Parameters of cardiac pump function ranged from normal to clearly pathological values. Mean pii was 13.0 mmHg on thorax and 8.3 mmHg on the ankle. Pi averaged -2.1 mmHg on thorax and -1.5 mmHg on the ankle. Statistically significant (P less than 0.05) correlations were found between pii on thorax and left ventricular end diastolic pressure (rs -0.40) and pii on thorax and cardiac index (rs 0.42). Pi was positively correlated to right atrial pressure (rs 0.50). Body fluid volumes were normal or moderately reduced. The study shows that a reduction in cardiac pump function is associated with a reduction in pii and a rise in Pi. These changes may help to prevent oedema formation in the early stages of heart failure.

Adult↗

Filariasis (Pelecitus sp.) in the cervical subcutaneous tissue of a pigeon with trichomoniasis.

Filariasis due to Pelecitus was found in the subcutaneous tissue of the neck of a domestic pigeon from Spain that died from trichomoniasis. Macroscopically, filariae were observed in the congested and hemorrhagic cervical connective tissue. Microscopically, a particular distribution of parasites with no inflammatory infiltrates was observed. Adult nematodes were located in peritracheal connective tissue and in the deep zone of the subcutaneous tissue. Microfilariae were mainly located in the superficial zone of the subcutaneous tissue. The only other changes observed were a moderate catarrhal tracheitis and congestion of the viscera.

Animals↗

Removal of exogenous plasma triglycerides in forearm muscle and subcutaneous tissue of hyper-and normotriglyceridaemic men.

Absolute arterio-venous removal and fractional removal of blood-borne exogenous triglyceride particles by skeletal and subcutaneous tissues were determined in eight normotriglyceridaemic and six hypertriglyceridaemic men. Estimations were made by simultaneously sampling blood from catheters inserted into a brachial artery, and in the distal direction, into a superficial and deep vein, draining subcutaneous tissue and skeletal muscle respectively. During the infusion of the fat emulsion IntralipidR for 3 hours steady arterial concentrations of exogenous TG particles were found, indicating first order kinetics. In all subjects absolute arterio-venous and fractional removal of triglycerides were about twice as high in skeletal muscle as in subcutaneous tissue. In skeletal muscle the fractional removal and absolute removal were significantly higher in normotriglyceridaemic than in hypertriglyceridaemic subjects (p less than 0.001). No decrease in removal with time was observed, which would have suggested saturation of removal sites. Mean fractional removal in skeletal muscle was significantly correlated with the k2 value determined by an intravenous fat tolerance test before the infusion study (r = 0.61, p less than 0.05). In subcutaneous tissue fractional removal was also significantly higher in normotriglyceridaemic subjects (p less than 0.05). The results suggest that in both skeletal muscle and subcutaneous tissue the removal system is impaired in hypertriglyceridaemic subjects. This finding supports the concept that a decreased elimination capacity in these tissues may partly account for triglyceride elevation in hypertriglyceridaemic subjects.

Adipose Tissue↗

Dynamic fibroblast cytoskeletal response to subcutaneous tissue stretch ex vivo and in vivo.

Cytoskeleton-dependent changes in cell shape are well-established factors regulating a wide range of cellular functions including signal transduction, gene expression, and matrix adhesion. Although the importance of mechanical forces on cell shape and function is well established in cultured cells, very little is known about these effects in whole tissues or in vivo. In this study we used ex vivo and in vivo models to investigate the effect of tissue stretch on mouse subcutaneous tissue fibroblast morphology. Tissue stretch ex vivo (average 25% tissue elongation from 10 min to 2 h) caused a significant time-dependent increase in fibroblast cell body perimeter and cross-sectional area (ANOVA, P < 0.01). At 2 h, mean fibroblast cell body cross-sectional area was 201% greater in stretched than in unstretched tissue. Fibroblasts in stretched tissue had larger, "sheetlike" cell bodies with shorter processes. In contrast, fibroblasts in unstretched tissue had a "dendritic" morphology with smaller, more globular cell bodies and longer processes. Tissue stretch in vivo for 30 min had effects that paralleled those ex vivo. Stretch-induced cell body expansion ex vivo was inhibited by colchicine and cytochalasin D. The dynamic, cytoskeleton-dependent responses of fibroblasts to changes in tissue length demonstrated in this study have important implications for our understanding of normal movement and posture, as well as therapies using mechanical stimulation of connective tissue including physical therapy, massage, and acupuncture.

Actins↗

Electromyographic recordings of paraspinal muscles: variations related to subcutaneous tissue thickness.

The aim of this study was to assess the effect on EMG amplitude measures of variations in the thickness of underlying tissue between surface electrodes and the active muscle. 20 normal subjects with different amounts of subcutaneous tissue performed comparable constant force contractions for a 45-second period, during which paraspinal EMG recordings were taken. Three measures of subcutaneous tissue thickness were obtained from each subject: Body Mass Index, total body fat as calculated by Durnin's formula, and skinfold thickness at the recording sites. The results show that (i) the greater the thickness of subcutaneous tissue between the surface recording site and the contracting muscles, the lower the recorded electromyographic activity, and that (ii) up to 81.2% of the variance in the EMG measures can be explained by variation in the amount of subcutaneous tissue. These findings support the view that the absolute level of surface-recorded EMG cannot simply be taken at face value. The amplitude of the signal will be affected by, for example, the amount of body fat.

Adipose Tissue↗

Attempts at autologous transplantation of sliced liver to the subcutaneous tissue.

Sliced rat liver was autologously transplanted to subcutaneous tissue. Morphology of the hepatocytes in transplants was investigated for up to 1 year after auto-transplantation; the effect of partial hepatectomy on the autografts was studied. Autografts with approximately one-tenth of the original weight were found alive in subcutaneous tissue for as much as 1 year after transplantation. Partial hepatectomy did not lead to greater weight.

Animals↗

Clinicopathological characteristics of peripheral primitive neuroectodermal tumour of skin and subcutaneous tissue.

AIMS: To study the clinical and pathological features of primary malignant peripheral primitive neuroectodermal tumours (PNETs) of the skin and subcutaneous tissue, to discuss the differential diagnosis, and to review the existing literature on these tumours. METHODS AND RESULTS: Eight cases of PNETs presenting in the skin and subcutaneous tissue were identified from the pathology records of the Christie Hospital, Manchester. Detailed immunohistochemical studies were performed on all cases and seven tumours were subjected to electron microscopic examination. Detailed clinical and follow-up information was obtained on seven cases. Six tumours occurred in children and adolescents and two were seen in young adults (age range, 8-36 years). No sex or site predilection was observed. Five tumours occupied the dermis and subcutis and three were entirely located in the subcutaneous tissue. Microscopically, they were composed of small round cells and seven tumours contained glycogen. Only one tumour focally exhibited Home-Wright rosettes and neuropil. Two tumours contained rhabdoid or plasmacytoid cells in places and all cases showed microcystic and pseudovascular spaces. Immunostains revealed MIC2 (8/8), NSE (7/8), PGP9.5 (7/8), beta 2 microglobulin (7/8), neurofilament protein (6/8), S100 protein (3/8), synaptophysin (2/8) and Leu-7 (1/8) positivity. Anomalous cytokeratin (4/8), desmin (2/8), myoglobin (2/8), NKIC3 (4/8) and GFAP (1/8) staining was also noted. Ultrastructurally, neuroendocrine granules were detected in five cases and one case exhibited microtubules in processes. Adequate follow-up information was available in four cases. One patient died of metastatic disease. One child developed axillary lymph node metastasis but is alive with no evidence of disease 96 months after treatment. Two other patients are alive with no residual or recurrent disease 44 and 52 months after excision and radio/chemotherapy. CONCLUSION: PNETs are rare malignant small round cell tumours of the skin and subcutaneous tissue which are probably underdiagnosed. A correct diagnosis can be made on light microscopic features, demonstration of neuroendocrine granules on electron microscopy and a combination of MIC2, beta 2 microglobulin, and more than one neural marker positivity. These neoplasms should be differentiated from other cutaneous neoplasms composed of small round cells. The number of cases of cutaneous PNETs studied so far is rather small, and no firm conclusion can be drawn about their behaviour but long-term survival is possible in some cases.

12E7 Antigen↗

Local and central sympathetic reflex control of blood flow in skeletal muscle and subcutaneous tissue in normal man.

The effect of age and sex on relative changes in blood flow and vascular resistance in skeletal muscle and subcutaneous tissue during postural changes and during local increase in transmural pressure was studied in 33 healthy subjects. The intra-individual variation was studied in five subjects. Blood flow was measured by the local 133Xenon wash-out method. No relation to age or sex was seen in the centrally elicited sympathetic vasoconstrictor responses in subcutaneous tissue and skeletal muscle and in the locally elicited vasoconstriction in subcutaneous tissue. A small, but statistically significant, correlation to sex and age was found in the local sympathetic vasoconstrictor response in skeletal muscle. The age correlation was caused only by an attenuated response in the young subjects below 40 years of age and may be fortuitous. The intra-individual variation was acceptably small. Based on the present results, a reduction in blood flow in skeletal muscle and subcutaneous tissue during centrally or locally elicited sympathetic vasoconstriction of 10% or less should be considered abnormal. The local 133Xenon wash-out method is of value in examining patients suspected of dysfunction in the sympathetic part of the autonomic nervous system.

Adult↗

Acute effect of scalding injury on blood flow in muscle and subcutaneous tissue in the paw of the anaesthetized dog.

Blood flow in muscle and subcutaneous tissue was studied before and after a scalding injury of the dog paw. The hydrogen clearance technique was used in anaesthetized dogs. As scalding of the paw resulted in an increased blood pressure and muscular movements, animals were given a muscle relaxant and ventilated artificially. Before scalding injury the blood flow was 29.8 and 19.7 ml per min per 100 g in muscular and subcutaneous tissue, respectively. After immersion of the paw for 10 sec in water of 100 degrees C the blood flow transiently increased and later decreased. No major changes were found in the contralateral paw. The decrease was most pronounced (50%) in subcutaneous tissue. In the acute situation the impeded circulation in the burn oedema may protect the organism from potentially harmful substances formed in the injured tissue.

Animals↗

Measurement of subcutaneous tissue fluid pressure using a skin-cup method.

We developed a new method for measuring tissue fluid pressure in subcutaneous tissue. Porous Teflon cylinders were permanently implanted subcutaneously into the inguinal area of 10 dogs, and after several weeks a skin concavity formed in the center of each of the cylinders. A small needle attached to a recording system was inserted into the free tissue fluid lining the concavity, and the tissue fluid pressure averaged -8.8 +/- 2.7 (SD) mmHg. Next, a hollow Plexiglas cup was placed over the concavity and glued to the skin. The air pressure in the skin cup was continually adjusted (using an electromechanical servo-control system) to pull the skin upward and to hold it perfectly flat across the upper ridge of the Teflon cylinder. The simultaneously recorded needle and cup pressures averaged -9.1 +/- 2.4 and -8.6 +/- 2.6 mmHg, respectively, during steady-state conditions with the skin in a flat position. Both pressures also responded appropriately to dynamic changes in tissue fluid pressure caused by increasing and decreasing the volume of the free tissue fluid. Because the skin was flat, the equivalences of pressures above and below the skin is consistent with the hypothesis that the skin was not tethered significantly to the underlying tissues and that cup pressure accurately estimates the tissue free fluid pressure.

Animals↗

Fatty acid composition of fats of differing melting points extracted from ram subcutaneous tissue.

The observation that the subcutaneous fat of pasture-fed Southdown rams consists of two distinct regions is reported. Fatty acid composition of fat from the outer and inner regions of subcutaneous tissue taken from the rib region of eight Southdown rams fed pasture were determined. Relative to the harder inner regions (mean melting point 43.1 degrees C), the softer outer regions (mean melting point 31.8 degrees C) were shown to contain more 9:0-, 15:0-, 17:0-, 17:1-, 18:1-cis and total 18:1 fatty acids; less 14:0-, 16:0-, 18:0- and 18:1-trans fatty acids; and a greater variety and a greater concentration of branched-chain components. Proportions of medium chain-length fatty acids, other than 9:0, did not differ between the layers. The fatty acid contents of serial samples taken at 1-mm intervals through these tissues were determined. Changes in concentrations of components among samples were gradual through the tissues. There was no clear connective tissue sheet, as has been reported for pigs. The inner region of the tissues contains apparently nonrandom fluctuating changes in fatty acid composition.

Adipose Tissue↗

[Prediction of fetal macrosomia using sonographically measured abdominal subcutaneous tissue thickness in pregnancies complicated by diabetes mellitus].

OBJECTIVE: The purpose of the study was to assess the clinical value of sonographically measured abdominal subcutaneous tissue thickness (SCTAd) in prediction of large for gestational age in pregnancy complicated by diabetes mellitus. MATERIAL AND METHODS: We prospectively evaluated 256 pregnant women with gestational and pregestational diabetes mellitus longitudinally from 24th week of gestation until delivery. In all cases sonography was performed, and abdominal subcutaneous tissue thickness was assessed. After delivery the entire examined group was divided into two groups. The first group comprised mothers who delivered newborns with birth weight above 90th percentiles, and the second group comprised mothers who delivered newborns with birth weight between 10th and 90th percentiles. RESULT: Based on statistical analyses SCTAd was bigger in Group I than Group II (p. < 0.01) at the beginning of the 31st week of gestation. Based on ROC (receiver operating characteristic) curves we estimated that 5 mm thickness of abdominal subcutaneous tissues differentiate AGA (appropriate for gestational age) and LGA groups with 71% sensitivity and 72% specificity. CONCLUSIONS: 1/Use of the SCTAd permitted diagnosis of asymmetric fetal overgrowth complicated by diabetes mellitus since 31st week of gestation 2/5 mm of abdominal subcutaneous tissue thickness allowed differentiate AGA and LGA with 71% sensitivity and 72% specificity in term pregnancies complicated by diabetes mellitus.

Abdomen↗

A correlation of the sequestration rate of Plasmodium coatneyi-infected erythrocytes in cerebral and subcutaneous tissues of a rhesus monkey.

Parasitized red blood cells (PRBCs) were sequestered in microvessels of cerebral and subcutaneous tissues of a rhesus monkey infected with Plasmodium coatneyi. A similar sequestration rate (approximately 80%) was observed in both cerebral and subcutaneous microvessels. Electron microscopy showed knobs of the sequestrated PRBCs cytoadhered to endothelial cells. These results are consistent with the finding of PRBC sequestration in subcutaneous tissues in a comatose patient with cerebral malaria. Biopsy specimens of subcutaneous tissue may be useful as indicators of PRBC sequestration in the brain of cerebral malaria patients.

Animals↗

Modified subcutaneous tissue with neovascularization is useful as the site for pancreatic islet transplantation.

The success rate of subcutaneous transplantation of pancreatic islets has been extremely low. Insufficient oxygen supply to the grafted islets is one possible major obstacle to the preservation of graft function. This study attempted to use basic fibroblast growth factor (bFGF) in subcutaneous transplantation to induce neovascularization and a sufficient blood flow around the space formed for grafted islets in the subcutaneous tissues. A bFGF-releasing device was designed enclosing bFGF in a polyethylene terephthalate mesh bag coated with polyvinylalcohol hydrogel. In the vascularized group (n = 5), two bFGF-releasing devices were implanted bilaterally into the subcutaneous tissue of the back of streptozotocin-induced diabetic Lewis rats. One week after implantation, isolated rat islets (5000) were syngeneically transplanted subcutaneously after the removal of the devices. In the control group (n = 5), no devices were implanted and the same number of rat islets was transplanted directly. One week after the implantation of the devices into the test animals, a thick, well-vascularized capsule was observed in the subcutaneous site. All vascularized recipient rats showed significant decreases in nonfasting blood glucose and maintained normoglycemia for more than 1 month after islet transplantation. However, in the control group, all rats failed to achieve normoglycemia after transplantation. This study provides evidence that the subcutaneous tissue is a promising site for pancreatic islet transplantation, offering convincing advantages in acceptability for diabetic recipients. Establishment of this subcutaneous islet transplantation technique will afford some new perspectives on successful clinical islet transplantation.

Animals↗

Towards continuous glucose monitoring: in vivo evaluation of a miniaturized glucose sensor implanted for several days in rat subcutaneous tissue.

A miniaturized amperometric, enzymatic, glucose sensor (outer diameter 0.45 mm) was evaluated after implantation in the subcutaneous tissue of normal rats. A simple experimental procedure was designed for the long-term assessment of the sensor's function which was performed by recording the current during an intraperitoneal glucose load. The sensor was calibrated by accounting for the increase in the current during the concomitant increase in plasma glucose concentration, determined in blood sampled at the tail vein. This made it possible to estimate the glucose concentration in subcutaneous tissue. During the glucose load, the change in subcutaneous glucose concentration followed that in blood with a lag time consistently shorter than 5 min. The estimations of subcutaneous glucose concentration during these tests were compared to the concomitant plasma glucose concentrations by using a grid analysis. Three days after implantation (n = 6 experiments), 79 estimations were considered accurate, except for five which were in the acceptable zone. Ten days after implantation (n = 5 experiments), 101 estimations were accurate, except for one value, which was still acceptable. The sensitivity was around 0.5 nA.mmol-1.l-1 on day 3 and day 10. A longitudinal study on seven sensors tested on different days demonstrated a relative stability of the sensor's sensitivity. Finally, histological examination of the zone around the implantation site revealed a fibrotic reaction containing neocapillaries, which could explain the fast response of the sensor to glucose observed in vivo, even on day 10. We conclude that this miniaturized glucose sensor, whose size makes it easily implanted, works for at least ten days after implantation into rat subcutaneous tissue.

Animals↗

In vivo evaluation of an electroenzymatic glucose sensor implanted in subcutaneous tissue.

Cleanroom processing techniques have been used to mass-produce flexible, electroenzymatic glucose sensors designed for implantation in subcutaneous tissue. In vitro characterization studies have shown the sensor's performance to be acceptable. Initial in vivo studies were conducted with the sensor implanted in the subcutaneous tissue of rabbits. Sensors implanted in the subcutaneous tissue of normal human subjects showed an excellent correlation between glucose concentrations measured by the sensor and capillary finger sticks measured with a commercial analyzer.

Animals↗

Reduction of the veno-arteriolar reflex induced arteriolar constriction in forearm subcutaneous tissue after surgical repair of aortic coarctation.

Arteriolar constriction in subcutaneous tissue elicited by the local sympathetic veno-arteriolar axon reflex was studied in subcutaneous tissue of forearm and leg in 4 patients before and after correction of aortic coarctation. Before the operation the local axon reflex induced an average increase of 154% in vascular resistance in the "hypertensive" forearm and of 76% in the leg. Following coarctectomy the local axon reflex induced increase in vascular resistance decreased in the forearm within 6 months in all patients. Now average increase in vascular resistance was only 109% 3 months after the operation and 45% 6 months after. Minimal vascular resistance in the papaverine relaxed vascular bed was reduced, whereas no systemic changes were seen in the distensibility of the vascular bed. The results indicate that adaptive vascular changes underlying the augmented arteriolar constriction during lowering as well as the increased "minimal vascular resistance" in the forearm are at least partly reversible following coarctectomy.

Adolescent↗