Transperineurial capillary abnormalities in the sural nerve of patients with diabetic neuropathy

Morphometric techniques were employed to assess perineurial capillary abnormalities in the sural nerve of 20 diabetic patients with neuropathy and 10 normal control subjects. Structural abnormalities were related to quantitative neurophysiological and neuropathological measures of neuropathy. Perineurial capillary endothelial cell area (P < 0.001) and endothelial cell profile number (P < 0.01) were increased and luminal area (P < 0.001) was reduced in diabetic patients when compared with control subjects. A significant relationship was observed between endothelial cell hyperplasia and measures of neuropathic severity. These findings provide evidence for perineurial capillary luminal occlusion due primarily to both endothelial cell hypertrophy and hyperplasia. Such a reduction in luminal size is expected to reduce transperineurial and hence endoneurial blood flow, resulting in endoneurial hypoxia and hence human diabetic neuropathy.     

Contrasting effects of treatment with omega-3 and omega-6 essential fatty acids on peripheral nerve function and capillarization in streptozotocin-diabetic rats

Essential fatty acid metabolism is impaired by diabetes mellitus and this may be important in the aetiology of peripheral nerve dysfunction. The effects of gamma-linolenic acid (omega-6) and fish oil (omega-3) alone, and in combination, on nerve function and capillarization were examined in 2-month streptozotocin-diabetic rats. Diabetes resulted in approximately 15% and 23% decreases in saphenous sensory and sciatic motor nerve conduction velocities, respectively (p < 0.001). Motor and sensory conduction velocities were in the non-diabetic range after both preventive and reversal omega-6 treatment of diabetic rats (p < 0.001). No significant changes occurred in omega-6 treated non-diabetic rats. Preventive omega-3 treatment was largely ineffective. Reversal treatment with a combination of omega-6 and omega-3 fatty acids was marginally effective and improved motor (p < 0.05), but not sensory conduction velocity. In vitro measurement of sciatic nerve resistance to hypoxic conduction failure in diabetic rats revealed a 56% increase in the time taken for the compound action potential amplitude to be reduced by 80% (p < 0.01) compared to non-diabetic rats. This was partially prevented by omega-6 treatment (29% increase, p < 0.01). Reversal omega-6 treatment had a lesser effect (37% increase, p < 0.05 compared to untreated diabetic rats). omega-3 treatment had no significant effect on conduction failure time. Sciatic endoneurial capillary density increased by 11% with preventive omega-6 treatment (p < 0.05), but was unaffected by reversal omega-6 and by omega-3 treatments.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bodenin: a novel murine gene expressed in restricted areas of the brain

Chronic vasodilatation represents a stimulus for capillary growth associated with increased luminal shear stress. We have examined the ultrastructure of more than 2000 capillaries to establish whether the sequence of angiogenesis in response to this stimulus is similar to that described during development and under pathological circumstances. Administration of the alpha1-blocker prazosin to rats for 2 weeks led to a greater capillary length density in extensor hallucis proprius muscles without any change in capillary tortuosity: Jv(c,f)=262+/-54 compared with 350+/-17 mm-2, control compared with prazosin (P<0.002). There were obvious signs of endothelial cell (EC) activation after prazosin treatment, including an increased proportion of capillaries with rough endoplasmic reticulum, large cytoplasmic vacuoles, thickened endothelium and an irregular luminal surface. Capillaries from control muscles had a maximum of three ECs in cross section, whereas four ECs were noted in 0.8+0.5% of capillaries after 1 week (n.s.) and 2.5+/-0.9% after 2 weeks (P<0.01) of treatment. This could be due to elongation and/or migration of ECs, as cell proliferation has not been described at these time points. There was also an increase in the proportion of capillaries having a narrow, slit-like lumen (1.7+/-0. 8% of controls; 7.1+/-1.9% at 1 week; 8.8+/-2.5% at 2 weeks; P<0.02), some of which were smaller in size (less than 2 microm diameter) than in controls (3-5 microm) and/or "seamless", i.e. lacking EC junctions. These may represent newly formed vessels. Focal discontinuity of the basement membrane and abluminal EC processes were rarely seen, and capillary growth by abluminal sprouting appeared to be very infrequent (less than 0.001% of profiles). Of more importance was growth starting from the luminal side. Significantly more thin cytoplasmic processes were observed protruding into the lumen of capillaries after 1 week (47.5+/-6.2%, P<0.001) and 2 weeks of prazosin (34.2+/-5.5%, P<0.05) than in control vessels (16.7+/-3.9%). Some of these traversed the entire lumen and connected with endothelium of the opposite side, probably involving membrane fusion, resulting in the appearance of a double lumen. Individual capillaries with a complete double lumen were observed after 2 weeks' prazosin but comparatively rarely, in only four out of six muscles. These findings indicate a pattern of luminal growth which is completely different from intussusceptive growth previously described during development, and from the abluminal capillary sprouting seen under pathological circumstances.     

Localization of human immunodeficiency virus 1 RNA in thymic tissues from asymptomatic drug addicts

The aim of the present study was to investigate if diabetes negatively influences the skin microvascular reactivity in the toes of patients with peripheral vascular disease (PVD). Twenty healthy subjects, 20 diabetic, and 20 non-diabetic patients with PVD participated. One foot in each subject was investigated. The patient groups were matched for age, sex, and toe pressure. The capillary blood cell velocity in the nailfold of the great toe was investigated by videophotometric capillaroscopy, and the total skin microcirculation within the same area by laser Doppler fluxmetry. Capillary blood cell velocity and laser Doppler flux were studied during rest, and following a 1 min arterial occlusion at the toe base. The skin microvascular reactivity was impaired in both diabetic and non-diabetic patients. In the diabetic patients the disturbances were mainly seen in the capillaries, and the capillary blood flow was severely reduced during reactive hyperaemia (p < 0.01). In contrast, the total skin microcirculation was normal, indicating that sufficient blood reaches the area, but does not come out into the capillaries. The ratio between capillary blood cell velocity and laser Doppler flux, representing the distribution of blood between nutritional and non-nutritional blood compartments, was reduced in the diabetic patients (p < 0.05). These findings may contribute to the higher risk for development of chronic foot ulcers in diabetic patients with PVD.     

Elements of the art of practice in mental health

This study examined links between impaired nitric oxide production in the sciatic endoneurium, nerve blood flow, and polyol pathway flux, to test the hypothesis that reduced nerve blood flow might be compromised by competition for NADPH between aldose reductase and nitric oxide synthase. Sciatic nerves of streptozotocin-diabetic rats showed reduced laser Doppler flux (by 51% or 63%; both p<0.05)-indicative of reduced nerve blood flow-and reduced motor nerve conduction velocity (17% in two experiments; p<0.05). Acute interruption of nitric oxide production in the sciatic nerves of control rats, via endoneurial injection of N omega-nitro-D-arginine methyl ester (L-NAME), caused a local reduction (of 64%; p<0.001) in nerve Doppler flux. This was reversed by either L-arginine or sodium nitroprusside. The response to L-NAME was greatly reduced in diabetic rats (only 22% reduction; p<0.01), though both L-arginine and SNP caused marked increases in flux. Chronic inhibition of aldose reductase in diabetic rats (with either sorbinil or imirestat at a range of doses) had little effect on resting sciatic nerve Doppler flux, though both inhibitors normalized conduction velocity. Both aldose reductase inhibitors reduced sorbitol pathway intermediates in a dose-related manner. These findings do not support the proposition that aldose reductase inhibitors normalise conduction velocity by mechanisms dependent upon either normalization of endoneurial nitric oxide or nerve blood flow. Instead, a mechanism based upon more direct effects on axon or Schwann cell function is favoured.     

Glucose transporters in rat peripheral nerve: paranodal expression of GLUT1 and GLUT3

Peripheral nerve depends on glucose oxidation to energize the repolarization of excitable axonal membranes following impulse conduction, hence requiring high-energy demands by the axon at the node of Ranvier. To enter the axon at this site, glucose must be transported from the endoneurial space across Schwann cell plasma membranes and the axolemma. Such transport is likely to be mediated by facilitative glucose transporters. Although immunohistochemical studies of peripheral nerves have detected high levels of the transporter GLUT1 in endoneurial capillaries and perineurium, localization of glucose transporters to Schwann cells or peripheral axons in vivo has not been documented. In this study, we demonstrate that the GLUT1 transporter is expressed in the plasma membrane and cytoplasm of myelinating Schwann cells around the nodes of Ranvier and in the Schmidt-Lanterman incisures, making them potential sites of transcellular glucose transport. No GLUT1 was detected in axonal membranes. GLUT3 mRNA was expressed only at low levels, but GLUT3 polypeptide was barely detected by immunocytochemistry or immunoblotting in peripheral nerve from young adult rats. However, in 13-month-old rats, GLUT3 polypeptide was present in myelinated fibers, endoneurial capillaries, and perineurium. In myelinated fibers, GLUT3 appeared to be preferentially expressed in the paranodal regions of Schwann cells and nodal axons, but was also present in the internodal aspects of these structures. The results of the present study suggest that both Schwann cell GLUT1 and axonal and Schwann cell GLUT3 are involved in the transport of glucose into the metabolically active regions of peripheral axons.     

Carbonyl histochemistry in rat reperfusion nerve injury

Free radical mediated, site-specific lipid and protein oxidation has been implicated in the pathophysiology of an ischaemic/reperfusion injury. The aim of the present study was to determine whether carbonyl formation could be detected histochemically in reperfused rat sciatic nerves. We also examined the effects of preischaemic alpha-tocopherol supplementation on carbonyl formation in reperfused nerves. Seven hours of near-complete ischaemia was induced in rat right hindlimb by occlusion of major arteries using microvascular clips. Histochemical detection of carbonyl compounds, applying naphthoic acid hydrazide (NAH) and Fast Blue B (FBB), was undertaken at thigh, knee and calf levels of sciatic, tibial and peroneal nerves. NAH-FBB reactivity was confined to vessels in reperfused nerves. Positively stained epi-, peri- and endoneurial vessels were invariably observed after 2 h of reperfusion at all levels examined. After 24 and 48 h and 7 days of reperfusion, NAH-FBB-positive vessels were more frequently found at knee and calf levels than at the thigh level. Following preischaemic alpha-tocopherol supplementation, no vessels were stained positively with NAH-FBB, except for some epineurial vessels at knee and calf levels after 2 h of reperfusion. Morphometry in endoneurial vessels at the knee level revealed that endothelial cell area in alpha-tocopherol-treated reperfused nerves was significantly less when compared with those in reperfused nerves without alpha-tocopherol. In conclusion, we have demonstrated histochemical evidence of carbonyl formation in vessels, but not with nerve fibres, in ischaemic/reperfused rat sciatic nerves. These abnormalities were prevented with preischaemic supplementation of alpha-tocopherol.     

Ultrastructural study of capillary and myocytic changes in the masseter and heart of KK-Ay mice

We studied the capillaries and myocytes of masseter and cardiac muscles of diabetic KK-Ay mice, using light microscopy, transmission electron microscopy and scanning electron microscopy. The following changes were observed for diabetic masseters: capillary tortuosity, diversity of capillary caliber, endothelial cell swelling accompanied by luminal narrowing, widening of the pericapillary space and pericapillary fibrosis, and subsarcolemmal accumulation of myocytic mitochondria in areas adjacent to capillaries. In addition, attenuated capillary segments were largely covered by pericytes with profuse processes. In contrast, cardiac muscles of KK-Ay mice exhibited subsarcolemmal accumulation of myocytic mitochondria in areas contiguous to capillaries, and degenerative changes of myocytes such as disarrangement of myofilaments, disappearance of Z-bands and clustering of lipid-like vacuoles, although conspicuous changes of capillaries were not noted. Microvascular and myocytic changes described above may suggest the presence of microangiopathy and myopathy in the masseter and heart of KK-Ay mice.     

Fish oil supplementation prevents diabetes-induced nerve conduction velocity and neuroanatomical changes in rats

Diabetic neuropathy has been associated with a decrease in nerve conduction velocity, Na,K-ATPase activity and characteristic histological damage of the sciatic nerve. The aim of this study was to evaluate the potential effect of a dietary supplementation with fish oil [(n-3) fatty acids] on the sciatic nerve of diabetic rats. Diabetes was induced by intravenous streptozotocin injection. Diabetic animals (n = 20) were fed a nonpurified diet supplemented with either olive oil (DO) or fish oil (DM), and control animals (n = 10) were fed a nonpurified diet supplemented with olive oil at a daily dose of 0.5 g/kg by gavage for 8 wk. Nerves were characterized by their conduction velocity, morphometric analysis and membrane Na, K-ATPase activity. Nerve conduction velocity, as well as Na,K-ATPase activity, was improved by fish oil treatment. A correlation was found between these two variables (R = 0.999, P < 0.05). Moreover, a preventive effect of fish oil was observed on nerve histological damage [endoneurial edema, axonal degeneration (by 10-15%) with demyelination]. Moreover, the normal bimodal distribution of the internal diameter of myelinated fibers was absent in the DO group and was restored in the DM group. These data suggest that fish oil therapy may be effective in the prevention of diabetic neuropathy.     

Dependence of centriole formation on protein synthesis

Electron microscope observations were made of rat peroneal nerve after crushing using intravenously injected horseradish peroxidase (HRP) as a tracer protein to indicate changes in vascular permeability. At 1/2 h and 2 d after the crush there was gross leakage of HRP from damaged capillaries at the site of injury but none from vessels above or below this. Ultrastructurally vessels at the site of crush showed broken and separated endothelial cells. Proximally and distally there was little abnormal in the vessel walls; vesicles containing HRP were absent and tight-junctions between cells remained intact. Twenty-one days after the crush, leakage of HRP was found both at the site of crush and along the distal segment. The only change in vessel walls was an obvious increase in vesicles filled with HRP. Tracer was also found both in perivascular locations and throughout the endoneurial space.     

Morphologic disturbance of lung maturation in fetuses of alloxan diabetic rabbits

Maturation of lungs was studied morphologically in fetuses of does made diabetic with alloxan. The lungs of fetuses of does treated with alloxan 24 h after mating appeared to be less mature than control lungs, as shown by significant decrease in areal density of air space (p < 0.01) and by increases in areal density of alveolar epithelium and capillaries (p < 0.02). In alloxan fetuses, ultrastructural techniques revealed that type II cells had 10 times the control value for areal density of glycogen (p < 0.01) and 2.5 times that of rough endoplasmic reticulum (p < 0.05), but the proportion of type II cells and the number of lamellar bodies per type II cell profile were similar in both groups. Ultrastructural examination of capillaries demonstrated that their migration and the fusion of their basement membrane with that of alveolar epithelium did not occur as frequently in alloxan fetuses as in control fetuses. Biochemically, the lungs of alloxan fetuses contained significantly more glycogen and protein (p < 0.01) than control lungs, but the deoxyribonucleic acid was similar. The alloxan fetuses had a disturbance of lung structural maturation that was consistent with our previous findings of delayed functional maturation without accompanying change in disaturated phosphatidylcholine levels and ratio of lecithin to sphingomyelin.     

A single glucose transporter configuration in normal primate brain endothelium: comparison with resected human brain

Cellular distribution of the Glut1 glucose transporter in normal primate brains was analyzed by immunogold electron microscopy. Two configurations of endothelial Glut1 glucose transporter (high and low density capillaries) have been found in resections of traumatically injured and epileptogenic human brain; the objective of the present study was to ascertain whether these same 2 capillary populations, expressing high and low glucose transporter densities, were the common configuration in normal brain. The relative numbers of Glut1 glucose transporter-associated gold particles on luminal and abluminal endothelial cell membranes were determined within the cerebral cortex of several normal, nonhuman primates. Low Glut1 densities were seen in brain endothelia of both the rhesus and squirrel monkey cortex, with slightly greater quantities of Glut1 in vervet monkey cortices. The Glut1 transporter was most highly expressed in the baboon cortex, approaching the concentrations seen in human brains. In the rhesus, squirrel, and vervet monkeys, Glut1 concentrations were greater on the abluminal than luminal capillary membranes. In contrast, mean luminal membrane Glut1 concentrations were greater in baboons, resembling the distribution seen in the human brain. Brain regional differences in transporter concentration were seen in comparing membrane densities in the baboon cortex (approximately 15 Glut1-gold particles per micrometer), hippocampus (approximately 12 Glut1 gold particles per micrometer), cerebellum (approximately 6 Glut1-gold particles per micrometer), and retinal microvasculature (approximately 20 Glut1-gold particles per micrometer). We conclude that a single, uniform Glut1 distribution characterizes brain capillaries of normal nonhuman primates, and hypothesize that the presence of high and low density glucose transporter endothelial cells (seen in human traumatic injury and seizure resections) represents a pathologic response to brain insult.     

Unmyelinated nerve fibers in senile nerves and in late thalidomide neuropathy: a quantitative electron microscopic study (author's transl)

Sural nerve biopsies of four patients, aged 54--76 years, with a predominantly sensory type of neuropathy following high dosages of thalidomide were examined by light and electron microscopy. The present study includes a qualitative and quantitative evaluation of unmyelinated nerve fibers. Despite severe neuropathy, increased numbers of small unmyelinated axons per endoneurial area were noted in all patients. This numerical increase appeared to be independent of aging, since it was not seen in two senile controls, studied at the age of 83 and 88 years. The increase in the endoneurial density of unmyelinated axons, especially of small sized fibers, is likely to be related to regeneration following degeneration of unmyelinated axons although endoneurial shrinkage secondary to loss of large myelinated fibers could have caused an additional increase in the number of axons per endoneurial area. Axonal sprouting, despite degeneration of large numbers of myelinated and unmyelinated fibers, appears to be consistent with some of the characteristic clinical features of thalidomide neuropathy such as paresthesias, hyperesthesia for pain and temperature, and disturbances of autonomic functions. On the other hand, a variable number of empty Schwann cells (bands of Büngner) and pockets at the surface of many Schwann cells noted in the four patients with neuropathy were also seen in both senile controls with no signs of neuropathy. Thus, it is obvious that pockets and empty Schwann cells may be related to aging or other causes of slow axonal wasting with Schwann cell proliferation and are not necessarily associated with clinically manifest neuropathy.     

Low-frequency submicron fluctuations of red blood cells in diabetic retinopathy

OBJECTIVE: To characterize cell membrane mechanical fluctuations of red blood cells (RBCs) in patients with diabetic retinopathy. METHODS: Point dark-field microscopy-based recordings of these local displacements of the cell membrane in human erythrocytes were compared between patients with severe proliferative diabetic retinopathy and healthy controls. The study was performed on discoid RBCs. RESULTS: The average of the maximal displacement amplitude in the diabetic patients was 13.9% +/- 1.7% (236 +/- 29 nm) compared with 18.7% +/- 1.75% (318 +/- 30 nm) for the controls (P<.001). The decrease of the RBCs' average displacement amplitude was not correlated with the variation in negative curvature of the central area of discoid cells. CONCLUSIONS: Microdisplacements of the cell membrane, which reflect the bending deformability of the RBCs, are directly connected with its efficiency in passing through capillaries narrower than its own diameter. These microdisplacements were significantly reduced in patients with severe diabetic retinopathy because of an increase in viscoelasticity of the cell membrane. Such reduced cell membrane microdisplacements, which reflect lower bending deformability of the RBC, reduce the ability of the cell to enter and pass through small capillaries, increasing tissue ischemia and consequently contributing to the development of diabetic retinopathy.     

Arterio-venous shunting and proliferating new vessels in acute painful neuropathy of rapid glycaemic control (insulin neuritis)

Insulin neuritis, or painful neuropathy following rapid improvement in glycaemic control, is well recognised but its aetiology is unclear. An understanding of the processes involved in the genesis of acute painful neuropathy of rapid glycaemic control may give an insight into the early pathogenetic factors leading to diabetic nerve damage in general. We have identified five subjects with insulin neuritis including one who developed severe autonomic neuropathy following treatment with insulin. Subjects underwent: 1) assessment of neuropathic symptom and deficit scores; 2) quantitative sensory and electrophysiological studies and 3) sural nerve epineurial vessel photography and fluorescein angiography in vivo. The sural nerve photographs were independently graded by an ophthalmologist. All subjects with insulin neuritis presented with severe sensory symptoms but clinical examination and electrophysiological tests were normal except in the subject with the severe autonomic neuropathy in whom all the tests were abnormal. On nerve photography, there was an abundance of epineurial nutrient vessels although these showed severe abnormalities including arteriolar attenuation, tortuosity and arterio-venous shunting in all subjects. Proliferating neural 'new vessels' which bear striking similarities to those found in the retina and that were more leaky to fluorescein than normal vessels, were observed in three subjects. Venous distension and/or tortuosity was also observed in three subjects and this was most marked in the subject with severe autonomic neuropathy. This study shows that epineurial nutrient vessel anatomy is abnormal in subjects with acute painful neuropathy of rapid glycaemic control, a condition previously thought to be purely metabolic in origin. The presence of epineurial arterio-venous shunting and a fine network of vessels resembling the new vessels of the retina, may lead to a 'steal' effect rendering the endoneurium ischaemic. This process may be important in the genesis of neuropathic pain, and further supports the importance of vascular factors in the pathogenesis of diabetic neuropathy.     

Aerobic exercise capacity remains normal despite impaired endothelial function in the micro- and macrocirculation of physically active IDDM patients

The aim of the present study was to examine if diabetes in the absence of neuropathy affects the exercising capacity of IDDM patients, and whether regular, intense training has a beneficial effect on endothelial function. Five groups of subjects were studied: 23 healthy control subjects who exercised regularly (age 33 +/- 6 years), 23 nonneuropathic type 1 diabetic patients who exercised regularly (age 33 +/- 6 years, IDDM duration 11 +/- 8 years), 7 neuropathic type 1 diabetic patients who exercised regularly (age 36 +/- 7 years, IDDM duration 22 +/- 8 years), 18 healthy subjects who did not exercise regularly (age 34 +/- 7 years), and 5 nonneuropathic type 1 diabetic patients who did not exercise regularly (age 31 +/- 4 years, IDDM duration 20 +/- 3 years). All groups were matched for age, sex, and body weight. No differences existed in the energy expenditure per week in physical activity among the three exercising groups or between the two nonexercising groups. The maximal oxygen uptake was similar between control and diabetic nonneuropathic exercisers, and among diabetic neuropathic exercisers, control nonexercisers, and diabetic nonexercisers; however, a significant difference existed between the first two and the last three groups (P < 0.0001). A stepwise increase was found in the resting heart rate among the groups, ranging from the lowest in control exercisers to the highest in diabetic nonexercisers, but the maximal heart rate was lower only in diabetic neuropathic exercisers compared with all other groups (P < 0.05). Assessments of endothelial function in both macro- and microcirculation were performed in 12 control exercisers, 10 diabetic nonneuropathic exercisers, 5 diabetic neuropathic exercisers, 17 control nonexercisers, and 4 diabetic nonexercisers. When all diabetic patients were considered as one group and all control subjects as another, the microcirculation endothelial function in the diabetic group was reduced compared with the control subjects (91 +/- 49 vs. 122 +/- 41% flux increase over baseline; P < 0.05). In contrast, no differences existed among the three diabetic groups or between the two control groups. Similarly, in macrocirculation, a reduced response during reactive hyperemia was observed in the diabetic patients compared with control subjects (7.0 +/- 4.5 vs. 11.2 +/- 6.6% diameter increase; P < 0.05), whereas again no difference existed among the three diabetic groups or between the two control groups. These data suggest that diabetes per se does not affect aerobic exercise capacity (VO2max) in physically active individuals, but is reduced in the presence of neuropathy. In addition, regular exercise training involving the lower extremities does not improve the endothelial function in the micro- and macrocirculation of the nonexercised upper extremity in type 1 diabetic patients.     

Laser Doppler imaging and capillary microscopy in ischemic ulcers

The local distribution of laser Doppler flux (mainly thermoregulatory perfusion) and capillary density (nutritive circulation) within 25 ischemic leg ulcers and their adjacent skin were investigated. For this purpose the technique of laser Doppler imaging and capillary microscopy were applied. In each ulcer a non granulation tissue area (NGTA), a granulation tissue area (GTA) and in adjacent skin a skin area (SA) were defined. In these areas the average laser Doppler area flux (arbitrary units, AU) and the number of capillaries/mm2 were determined for each patient. The mean+/-S.D. of laser Doppler area fluxes were: NGTA 1.30+/-1.93, GTA 2.13+/-1.53 and SA 1.21+/-0.77 AU, respectively. The differences between GTA and NGTA or SA was statistically significant (p < 0.001, each) The mean+/-S.D. of capillary densities were as follows: NGTA: 0.56+/-2.06, GTA 6.76+/-8.39 and SA 16.80+/-7.38 capillaries/mm2, respectively. The following differences were statistically significant: NGTA versus GTA (p < 0.01) and SA versus NGTA or GTA (p < 0.001, each). In conclusion following characteristics of the three areas can be described: In NGTA low laser Doppler area flux is combined with very low capillary density (ulcer area without healing). In GTA the highest laser Doppler area flux of all three areas and an intermediate capillary density (wound healing) is found. In SA an intermediate laser Doppler area flux is associated with the highest capillary density of all three areas with the healing process nearly completed and no granulation tissue.     

NGF, cyclic AMP, and phorbol esters regulate oxytocin receptor gene transcription in SK-N-SH and MCF7 cells

In an initial study, the effects of galactose intoxication on nerve laser Doppler blood flow (NLDF) and nerve conduction velocity (NCV) were assessed after 1-16 weeks of galactose feeding in pentobarbital-anesthetized rats. NLDF was not significantly changed at any time point. NCV was significantly reduced after 16, but not 1 or 4, weeks of galactose feeding. In a second study, NLDF was not significantly changed by 4 weeks of galactose intoxication, but streptozotocin-diabetic NLDF was significantly reduced compared to both control (P<0.001) and galactose-intoxicated rats (P<0.05). Compared to control animals, sciatic motor NCV was significantly (P<0.001) reduced in the galactose group, while sciatic and saphenous sensory NCVs were not significantly changed. In the streptozotocin-diabetic rats, motor and sensory NCVs were all significantly reduced (P<0.001). In contrast to the NCV findings, mean caliber of myelinated axons in both the saphenous and sciatic nerves was reduced in galactose-intoxicated, but not streptozotocin-diabetic rats. The observed sequence of changes associated with these two models of diabetic neuropathy is not consistent with the proposed roles of ischemia and axonal dwindling in the reported nerve conduction deficits.     

Total-body skeletal muscle mass: evaluation of 24-h urinary creatinine excretion by computerized axial tomography

We retrospectively reviewed the results of operative decompression for peroneal nerve palsy in thirty-one patients who had been managed between 1980 and 1990. All patients had been managed non-operatively for at least two months after they had initially been seen. Intraoperatively, we found epineurial fibrosis and bands of fibrous tissue constricting the peroneal nerve at the level of the fibular head and at the proximal origin of the peroneus longus muscle. At a mean of thirty-six months (range, twelve to seventy-two months) postoperatively, thirty (97 per cent) of the thirty-one patients reported subjective and functional improvement and were able to discontinue the use of the ankle-foot orthosis. In contrast, only three of nine patients who had been managed non-operatively reported subjective and functional improvement (p < 0.01). Peroneal nerve palsy does not always resolve spontaneously; if it is left untreated, the loss of dorsiflexion of the ankle and persistent paresthesias can result in severe functional disability. Therefore, if non-operative measures do not lead to improvement within two months, we believe that operative decompression should be considered.     

The homing pigeon hippocampus and the development of landmark navigation

The temporo-spatial patterning of lectin-binding sites was examined by lectin histochemistry and quantitative methods in the microvasculature of the optic tectum of 9-, 14-, 20-day-old embryos and 30-day-old chickens. Horseradish peroxidase and colloidal-gold-labelled lectins were used for detection of beta-D-galactose (RCA-I, Ricinus communis agglutinin-I) and of N-acetylglucosamine and sialic residues (WGA, Wheat germ agglutinin) at light and electron microscopical levels. At the light microscopical level, RCA-I and WGA binding sites were detectable in the early embryonic capillaries in a diffuse staining pattern; in later embryonic stages and in adult animals, RCA-I labelling became located on the abluminal surface of the vessels, while WGA staining was detected on the luminal surface. Ultrastructurally, gold labelling for RCA-I was seen intracytoplasmically in endothelial cells in 9-day-old embryos. In 14-to 20-day-old embryos and in chickens, binding sites for RCA-I were detected in endothelial tight junctions and basement membranes. In contrast, labelling of the gold-coupled WGA lectin was distributed almost exclusively on the luminal endothelial surface already in early embryos. The results indicate that the endothelial cells of the optic tectum acquire functional polarity early in their development and that glycoconjugates containing beta-D-galactose residues are involved in the biochemical composition of the tight junctions and basement membrane, which are considered to be key structures in blood-brain barrier (BBB) differentiation.