Use of the guinea pig flank flap in skin flap research

A variety of flaps in laboratory animals have been designed that propose to parallel the behavior of human skin under different experimental conditions. In the search for a readily available and affordable island skin flap model that combines reliable anatomy with a pedicle of substantial size, we have designed in the guinea pig a cutaneous flap based on the superficial circumflex iliac artery and vein. In 22 adult female Hartley guinea pigs, an 8 x 4 cm flank flap based on the superficial circumflex iliac pedicle was raised, and its characteristics were evaluated for applications to skin flap research. Dermofluorometric studies were performed that confirm the vascularity of this flap, and 100% survival of the flap was seen 5 days after surgery in all animals. Of particular benefit was the demonstration that both afferent and efferent blood samples can be taken from the pedicle directly, which allows for the direct quantification of plasma markers after physiologic insults to the skin flap, such as burn or ischemia. This anatomically reliable and easily dissected flap lends itself well to preliminary skin flap research and may contribute to standardization of a model for further studies examining the behavior of skin microcirculation under adverse physiologic conditions.

Use of the Guinea Pig Flank Flap in Skin Flap Research

A variety of flaps in laboratory animals have been designed that propose to parallel the behavior of human skin under different experimental conditions. In the search for a readily available and affordable island skin flap model that combines reliable anatomy with a pedicle of substantial size, we have designed in the guinea pig a cutaneous flap based on the superficial circumflex iliac artery and vein. In 22 adult female Hartley guinea pigs, an 8 × 4 cm flank flap based on the superficial circumflex iliac pedicle was raised, and its characteristics were evaluated for applications to skin flap research. Dermofluorometric studies were performed that confirm the vascularity of this flap, and 100% survival of the flap was seen 5 days after surgery in all animals. Of particular benefit was the demonstration that both afferent and efferent blood samples can be taken from the pedicle directly, which allows for the direct quantification of plasma markers after physiologic insults to the skin flap, such as burn or ischemia. This anatomically reliable and easily dissected flap lends itself well to preliminary skin flap research and may contribute to standardization of a model for further studies examining the behavior of skin microcirculation under adverse physiologic conditions.

Improved efficacy of urokinase further prolongs ischemic skin-flap survival

Salvage of a free-tissue transfer, when postoperative vascular compromise is detected, depends largely upon the restoration of a patent microcirculation. The therapeutic efficacy of thrombolytics infused directly into the failing flap has been clearly demonstrated. In this experiment, the authors investigated whether the method of selective administration of urokinase to failing skin flaps in 68 Sprague-Dawley rats had any effect on flap survival. In one group of animals, postischemic flaps were perfused with 100,000 IU of urokinase given by manual injection, and via a pressurized delivery system (150 mmHg) in the other group. Flap survival was assessed at 7 days. A significantly greater survival was seen in flaps treated with urokinase by controlled pressure infusion (p < 0.01). This simple method is suggested to increase the efficacy of urokinase used in the context of flap salvage.

[Studies of long-term cryopreservation of hepatocytes and their transplantation treating acute hepatic failure in Wistar rats]

The experiment aimed at studying long-term cryopreservation of hepatocytes and therapeutic effect of their transplantation for acute hepatic failure. Hepatocytes of wistar rats were cryopreserved in liquid nitrogen for 30, 60, 90, and 180 days. Their viabilities were respectively 71.2%, 75.7%, 69.7%, and 73.5% of fresh cells', however, there were no significant differences among all cryopreserved groups. Differences of viably intra-hepatocellular enzyme contents among all groups, such as glutamic oxaloacetic transaminase and so on, were not significant. Morphologically intact hepatocytes were observed under light microscopy and transmission electron microscopy. Survival rate of Sprague-Dawley rats with acute hepatic failure were increased from 1/8 to 5/7 because of the transplantation of syngeneic frozen hepatocytes (P = 0.035). The results showed that after 30 days of cryopreservation in liquid nitrogen, the viability of hepatocytes decreased significantly, but no longer decreased in subsequent freeze up to 180 days. The viable intact cells and their normal enzyme contents were kept. The acute hepatic failure could be treated by them.

Iloprost improves survival of ischemic experimental skin flaps

The ability of the prostacyclin analogue iloprost to improve survival of ischemic experimental skin flaps was investigated. Unilateral island skin flaps based on the superficial inferior epigastric vessels were raised in 70 rats and subjected to varying lengths of primary ischemia. The flaps were divided into the following four groups: group I, no perfusion washout; group II, postischemic washout with lactated Ringer's solution; group III, postischemic washout with urokinase; and group IV, postischemic washout with iloprost. Flap survival rates for group IV were significantly higher than all other groups (p < 0.05). The primary ischemia time at which 50% of the flaps failed was 8.9 hours for group I, 9.5 hours for group II, 13.3 hours for group III, and 15.3 hours for group IV. This is the first study to investigate the effect of iloprost on skin flap survival. Iloprost was found to be significantly more effective than urokinase in salvaging ischemic experimental skin flaps.

Use of urokinase during secondary ischemia in experimental skin flaps

The ability of urokinase to salvage experimental flaps after a secondary ischemic insult was investigated in a rat model. Unilateral abdominal island skin flaps based on the superficial inferior epigastric vessels were raised and subjected to either 4 or 6 hours of primary ischemia followed by 12 hours of reperfusion and varying lengths of secondary ischemia. At the conclusion of secondary ischemia, the flaps were perfused with either lactated Ringer's solution or urokinase. One group of flaps served as a control and received no postischemic perfusion washout. The secondary critical ischemia time at which 50% of the flaps failed clinically was greater for flaps perfused with urokinase. Furthermore, the survival rates for all flaps perfused with urokinase were significantly greater than either control flaps or flaps perfused with lactated Ringer's solution (p < 0.05). Flap survival decreased significantly in all groups with increasing primary and/or secondary ischemia time (p < 0.05).

Epidemiology of age-related dementia in China

The results of these epidemiological studies suggest that the morbidity of age related moderate and severe dementia among the population of 65+ was 1.82%, when adjusted by 1984 US population ratio, it became 3.2%, as reported by US and European authors. Yet MID appears more common than PDD, which was more close to the data from Japan. The average annual incidence of moderate and severe dementia for persons aged 60+ was 0.3% (95% CI: 0.08%-0.52%). The incidence for those aged 70-79 (0.41%) was similar to that reported by US authors (Sluss), 0.58% among 70-74 years old, but lower than that observed by European authors (Hagnell, Magnusso) varied from 1.2% to 5.2% in the same age group. These great differences are likely to be partly due to differences in the age structure of samples, instruments for testing dementia, and diagnostic criteria. The course and outcome of dementia after 3-year follow-up indicated that the average survival time was 8 years, and the risk for death of dementia was 3 times higher than that of the whole cohort; the results were similar to those reported by westerners. The major risk factors for AD as identified in this study showed that family history both in first degree relatives of AD and psychosis were significantly associated with AD. The finding was consistent with the genetic hypothesis in western countries. In 7 risk factors that have been studied in US and European countries, 6 showed that the family history of dementia was significantly associated with AD.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhancement of fluorescein perfusion in experimental skin flaps following postischemic washout with iloprost, urokinase, verapamil, and University of Wisconsin solution

The enhancement of blood flow in experimental skin flaps following postischemic perfusion washout was investigated in rats. Unilateral island skin flaps based on the superficial epigastric vessels were raised and subjected to 6 hr of primary ischemia. Group 1 was designated as a control and did not undergo postischemic perfusion washout. In the remaining rats, postischemic washout was performed with one of five agents: Group 2--lactated Ringer's solution; Group 3--University of Wisconsin solution, an organ preservation medium; Group 4--verapamil, a calcium channel blocker; Group 5--urokinase, a thrombolytic agent; Group 6--iloprost, a stable prostacyclin analog. Two hours following perfusion washout, fluorometric analysis revealed a statistically significant enhancement of blood flow in Groups 4, 5, and 6, compared to Groups 2 and 3 (p < 0.05). Furthermore, a significant increase in skin surface fluorescence was demonstrated in all the flaps that underwent perfusion washout, compared to the control flaps (p < 0.05). By analyzing skin surface fluorescence, the enhancement of nutritive blood flow in flaps, following postischemic perfusion washout, was evaluated. This is the first study in which the above pharmacologic agents were compared in a quantitative manner.

Hemodynamics of the rodent abdominal skin flap following primary ischemia

The effect of varying periods of ischemia and reperfusion times on subsequent blood flow was studied in the rodent abdominal skin flap. Using perfusion fluorometry, measurements of blood flow were quantified in 60 Sprague-Dawley rats undergoing clamp-induced ischemic periods ranging from 0 to 6 hours and reperfusion times ranging from 2 to 8 hours. Flaps subjected to ischemia times of 0, 2, 4, or 6 hours require 8 hours of reperfusion time before reaching baseline levels of blood flow. Blood flow in flaps subjected to 6 hours of ischemia was statistically less than the flow in flaps ischemic for 0, 2, and 4 hours and was directly related to length of reperfusion. These results demonstrate that flap perfusion does not fully take place immediately after clamp release. The factors thought to be responsible for these findings and the implications for the design and interpretation of flap ischemia experiments are discussed.

The additive beneficial effect of UW solution and urokinase on experimental microvascular free-flap survival

Pharmacologic manipulation of free flaps to enhance tolerance to ischemia has become a subject of great interest in the research literature. In an effort to improve survival, perfusion washout of experimental free flaps was performed following an episode of primary ischemia. The perfusates utilized were lactated Ringer's solution (LR), University of Wisconsin solution (UW), a high-molecular-weight medium used in organ preservation, and urokinase, a thrombolytic agent. Seventy-five rats were used in this study and divided into groups of 5 each. A 3 x 6-cm abdominal free flap based on the superficial inferior epigastric vessels was raised in each rat. The free flaps were subjected to either 12 or 18 hr of primary ischemia. Following the period of ischemia, perfusion washout was performed with either LR, UW solution, or urokinase at increasing concentrations alone or in combination with UW solution. Urokinase was first evaluated as a perfusate alone at increasing concentrations. In the 12-hr ischemia group, free-flap survival was shown to increase from 0 percent in the LR-perfused flaps to 20 percent, 60 percent, and 80 percent in flaps perfused with 12,500, 25,000, and 100,000 U of urokinase, respectively (p < 0.05). A similar increase in survival was demonstrated in the 18-hr ischemia group, where 0 percent, 20 percent, and 40 percent of flaps survived following perfusion with 12,500, 25,000, and 100,000 U of urokinase, respectively (p < 0.05). Urokinase was then perfused along with UW solution to evaluate the combined effect on flap survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Prolongation of secondary critical ischemia time of experimental skin flaps using UW solution as a normothermic perfusate

A myriad of investigations have been published on the pharmacologic manipulation of flaps to enhance tolerance to ischemia. We recently reported a threefold increase in ischemic tolerance of the rat abdominal skin flap pedicle after 6 hours of primary ischemia and 12 hours of reperfusion. Flaps underwent normothermic perfusion washout with lactated Ringer's or U.W. solution, a newly developed organ preservation medium. Perfusion washouts were performed at one of three different points in the protocol: (1) onset of primary ischemia; (2) onset of secondary ischemia; or (3) 2 hours after onset of secondary ischemia. The last group was used to simulate the clinical situation in which flaps are discovered and salvage procedures instituted at a delayed time interval. This is the longest normothermic ischemic interval reported. We undertook the present study to determine the utility of the U.W solution in prolonging the tolerance of the flap to a second ischemic insult after a period of reperfusion. Seventy-five unilateral rat abdominal skin flaps were raised. Secondary ischemia was produced by placing a microvascular clamp across the inferior epigastric pedicle. Flap survival was assessed at 1 week postoperatively. While none of the nonperfused flaps survived 8 hours of secondary ischemia, at least 50% of the U.W. perfused flaps survived an average of 14 hours of secondary ischemia. Lactated Ringer's perfusion washout only modestly increased the ischemic tolerance. Perfusion washout in the secondary ischemic phase improved the ischemic tolerance to a significantly greater degree than in the primary ischemic interval.

UW solution as an experimental microvascular skin flap perfusate

UW solution has been found to be an effective organ perfusate for transplantation. Initial studies in experimental pedicle skin flaps have also demonstrated its unique effectiveness in prolonged ischemia. To understand better the limits of its preservation properties without the influence of endothelial clamp damage, we have undertaken to study the properties of UW solution in experimental microvascular free flaps. Control, lactated Ringer's, and UW solutions were utilized in pedicle and microvascular free flaps in Sprague-Dawley rats over varying periods of ischemia. UW solution demonstrated a clear superiority over all other solutions in both flap models. In addition there also was a significant prolongation of critical ischemia time in UW-treated free flaps compared to pedicle flaps.

Impaired visual evoked potential and primary axonopathy of the optic nerve in the diabetic BB/W-rat

The spontaneously diabetic BB/W-rat has emerged as an important model system for somatic and autonomic diabetic polyneuropathy. In this study we examined visual evoked potentials and the presence of morphometric and structural changes in the optic nerve and the retinal ganglion cells and their afferent axons contained in the retinal nerve fibre layer. A six-month duration of diabetes mellitus was associated with significant increases in the latencies of the visual evoked potentials. The latency of the first positive potential showed a 44% increase, and that of the first negative potential was prolonged by 41%. No significant changes were demonstrated at any of the amplitudes. In the optic nerve mean myelinated fibre size was significantly reduced to 82% of control values, which was accounted for by a significant reduction in axonal size. Axo-glial dysjunction, a prominent structural defect of diabetic somato-sensory neuropathy in both man and diabetic rodents, was non-significantly increased in the optic nerve. In diabetic animals retinal ganglion cells displayed dystrophic changes. No such changes were observed in age- and sex-matched control animals. Proximal axons of the retinal nerve fibre layer showed an increase in dystrophic axons in diabetic BB/W-rats. Morphometric analysis of optic nerve capillaries revealed no abnormalities except for basement membrane thickening. The present data suggest that the diabetic BB/W-rat develops a central sensory neuropathy, characterized functionally by prolonged latencies of the visual evoked potentials and structurally by an axonopathy of optic nerve fibres.

Temporal factors affecting the secondary critical ischemia of normothermic experimental skin flaps

In free tissue transfer surgery all flaps are subjected to a primary ischemic episode prior to reperfusion. Some flaps may fail due to a second ischemic insult in the postoperative period. The maximum allowable time for salvage of such failing flaps is referred to as the secondary critical ischemia time. Unilateral abdominal island skin flaps based on the superficial inferior epigastric vessels were raised in 96 Sprague-Dawley rats. Animals were divided into 24 groups of four rats each. Normothermic ischemia was produced by applying microvascular clamps to the vascular pedicles. The flap groups were subjected to combinations of primary ischemia, reperfusion, and secondary ischemia. Flap survival was assessed on the seventh postoperative day. Flap survival decreases significantly with increased primary and/or secondary ischemia time and decreased reperfusion period. Moreover, a longer primary ischemia and/or shorter reperfusion decrease the tolerance of the flap to a second ischemic insult.

The use of a new perfusate in experimental microvascular flaps: a threefold increase in ischemic tolerance

The benefit of perfusion washout in both experimental and clinical skin flaps has long been debated. By perfusing ischemic rat pedicled flaps with UW solution, a recently developed, high-molecular-weight, organ-preservation medium, a 170 percent increase in the critical ischemia time of treated versus untreated control flaps was demonstrated. Sixty rats were used in this study. A 3- x 6-cm unilateral abdominal skin flap based on the superficial inferior epigastric artery and vein was raised. The flaps were divided into three groups: Group 1 (control--no perfusion washout (n = 15); Group 2 (LR)--perfusion washout with lactated Ringer's solution (n = 15); Group 3 (UW)--perfusion washout with UW solution (n = 30). Flaps were subjected to varying periods of ischemia, ranging between 8 and 30 hr. The primary ischemia time at which 50 percent of the flaps survived clinically was 10 hr for Group 1, 15 hr for Group 2, and 27 hr for Group 3. The differences between the survival rates for flaps in Groups 1, 2, and 3 were statistically significant (p less than .0005). By bathing the vascular and parenchymal cells in an impermeant preservation solution, it was hypothesized that cellular swelling would be inhibited, thereby significantly improving a skin flap's tolerance to warm ischemia. Furthermore, after reviewing the pertinent literature, it is evident that the primary critical ischemia time of 27 hr is the highest reported to date for the normothermic experimental rat pedicled flap. Clinical application of these findings, as well as the need for further studies, are discussed.

Diabetic autonomic neuropathy in BB rats and effect of ARI treatment on heart-rate variability and vagus nerve structure

The preventive effect of the aldose reductase inhibitor (ARI) ponalrestat on heart-rate variability and the development of autonomic neuropathy in the vagus nerve was investigated in the spontaneously diabetic BB rat. ARI treatment completely prevented the characteristic decrease in heart-rate variability and axonal atrophy of the vagus nerve for 4 mo in hyperglycemic BB rats. After 6 mo of treatment, the preventive effect on heart-rate variability was partial, and the vagus nerve demonstrated an increase in regenerating myelinated and unmyelinated fibers. These data suggest that autonomic neuropathy involving the vagus nerve is metabolically induced by demonstrating that inhibition of the polyol pathway significantly delays the occurrence of functional and structural autonomic neuropathy despite the presence of hyperglycemia.

Preventive effect of long-term aldose reductase inhibition (ponalrestat) on nerve conduction and sural nerve structure in the spontaneously diabetic Bio-Breeding rat

To test the hypothesis that aldose reductase inhibition may prevent or delay the development of functional and structural neuropathy in the insulin-deficient diabetic Bio-Breeding rat (BB-rat), hyperglycemic rats were begun on the aldose reductase inhibitor (ARI) ponalrestat 25 mg/kg body wt soon after the onset of diabetes and followed for 4 or 6 mo. Ponalrestat treatment completely prevented the characteristic nerve conduction slowing and structural abnormalities of the node of Ranvier for 4 mo despite only partial preservation of axonal integrity. Ponalrestat treatment for 6 mo achieved a partial but significant prevention of nerve conduction slowing, axoglial dysjunction, and axonal degenerative changes. This incomplete but significant prevention of neuropathy by ponalrestat suggests that additional mechanisms besides polyol-pathway activation may be of importance in the pathogenesis of diabetic neuropathy. Alternatively, the dosage used in the present study may not have been sufficient to achieve a complete prevention. Despite the only partial protective effect of ARI treatment on degenerative peripheral nerve changes in hyperglycemic BB-rats, 6 mo of treatment resulted in a more than threefold increase in regenerating nerve fibers. These data suggest that prophylactic ARI treatment may be efficacious in delaying the development of diabetic neuropathy.

Neuroaxonal dystrophy in distal symmetric sensory polyneuropathy of the diabetic BB-rat

We and others have previously described neuroaxonal dystrophic changes as one of the hallmarks of structural diabetic autonomic polyneuropathy involving sympathetic nerves. In the present study, a systemic search for similar changes was undertaken in the mainly sensory symmetric polyneuropathy of the spontaneously diabetic BB-rat. Changes identical to those described in sympathetic nerves in this model were found in sensory ganglion cells, in their proximal extramedullary axons, and in proximal and distal myelinated axons of the spinal dorsal columns. The dystrophic substructures consisted of tubulovesicles, tubular rings, layered membranes, electron-dense membranous bodies, and neurofilamentous changes. Neuroaxonal dystrophic abnormalities increased with increasing duration of diabetes, and exhibited a topographic distribution along the sensory neuroaxonal axis, suggesting metabolic abnormalities as well as abnormalities in the turn-around mechanism of fast axonal transport in the pathogenesis of dystrophic changes in diabetic nerves.

Autonomic neuropathy in BB rats and alterations in bladder function

In vivo urinary bladder function was examined in BB rats after 4 and 6 mo of diabetes, and the data were correlated with morphometric changes in the pelvic and hypogastric nerves, which constitute the micturition reflex arc. After controlled bladder distension, diabetic animals revealed irregular bladder contractions at frequencies that were reduced to 33% of normal values and with significantly increased amplitudes. The abnormal micturition in diabetic animals was elicited at moderately elevated threshold volumes. These functional abnormalities of the diabetic bladder were associated with a progressive axonopathy of afferent myelinated sensory fibers and later-occurring axonal atrophy of unmyelinated efferent preganglionic fibers. These data suggest that diabetic urinary bladder dysfunction is initiated by a visceral sensory neuropathy involving the afferent limb of the micturition reflex arc.

Diabetic and hypoglycemic neuropathy--a comparison in the BB rat

Functional and structural neuropathy was examined in hyperglycemic (diabetic) BB rats maintained on small maintenance doses of insulin, hyperglycemic BB rats receiving no insulin, and BB rats in whom hypoglycemia was induced by the administration of excessive insulin doses. The data were compared with those of non-diabetic age- and sex-matched BB rats. Functional deficits and structural abnormalities were comparable in diabetic rats with and without insulin supplementation, suggesting that the generally necessary insulin dosing in this model does not per se account for the neuropathy. Hypoglycemic neuropathy was characterized by slowing of nerve conduction velocity, marked loss of anterior horn motoneurons and Wallerian degeneration, as well as loss of large myelinated fibers, suggesting a neuropathy involving predominantly motoneurons. Diabetic neuropathy was not associated with nerve cell loss but showed marked axonal atrophy involving predominantly sensory fibers. Thus, diabetic and hypoglycemic neuropathies are two distinguishable entities under strict experimental conditions, but may overlap in human diabetic subjects in whom tight insulin control is desirable.

Diabetic neuropathy in STZ-induced diabetic rat and effect of allogeneic islet cell transplantation. Morphometric analysis

The effect of pancreatic islet cell allotransplantation on the development of diabetic neuropathy in streptozocin-induced diabetic ACI rats was examined morphometrically with light- and electron-microscopic procedures. Peripheral nerve function was evaluated by nerve conduction velocity and evoked muscle potential amplitude measurements. Diabetes was induced at 4 mo of age, and diabetic animals were transplanted by intracerebral and intraportal grafts 2 wk later. Diabetic animals with accepted grafts returned to euglycemia and showed a normal body-weight gain over the subsequent 14-mo observation period. Transplanted animals with accepted grafts and those in whom graft rejection was induced were compared with age-matched nontransplanted diabetic rats and nondiabetic control rats at 18 mo of age. Successful allotransplantation completely prevented axonal atrophy and the characteristic nodal and paranodal structural abnormalities in diabetic nerve, as well as the typical slowing of nerve conduction velocity. Our data suggest that islet cell allotransplantation is an effective therapeutic approach to the prevention of diabetic neuropathy.

Somatic embryogenesis and plant regeneration in callus from inflorescences of Hordeum vulgare X Triticum aestivum hybrids

Embryogenic callus cultures were obtained by culturing young inflorescence tissues of Hordeum vulgare cv. 'PF51811' (2x)XTriticum aestivum cv. 'Chinese Spring' (6x) hybrids on 2,4-D-containing N6 medium. After subculture for about 10 months the calli retained a high potentiality for somatic embryogenesis and plant regeneration. Of about 300 regenerated plants, approximately 100 were transplanted to potting soil. Eight embryoids and three regenerated plants examined had 28 chromosomes identical to the original hybrid plants, while one regenerated plant was found to be a mixploid composed of cells with 28 and 56 chromosomes. The possibility for obtaining amphiploid hybrids through tissue culture is discussed.

Quantitative analysis of Roussin red methyl ester in pickled vegetables

In a study of the etiological factors in esophageal cancer, Roussin red methyl ester was isolated and identified in pickled vegetables of Linxian County, North China, where there is a high incidence of esophageal cancer. In this paper, a method is described for quantitative analysis of Roussin red methyl ester in pickled vegetables by gas chromatography-high-resolution mass spectrometry single-ion monitoring. The content of Roussin red methyl ester in pickled vegetables from Linxian has been found to be 0.1 to 4.5 mg/kg, and that from Beijing is below 0.005 mg/kg, which is the detection limit of the analytical method used. The marked difference between the contents might be one of the possible reasons for the difference in esophageal cancer incidence between the two regions.