Morphological Signs Of Damage Research Articles

Comparative analysis of the effectiveness of local application of vitamin D3 and 5-aminosalicylic acid in experimental colitis

Introduction. At the moment in the Russian Federation there are no dosage forms with vitamin D3, allowing effective delivery and local effect on the focus of inflammation and the damaged area of the large intestine in inflammatory bowel disease (IBD). Among such dosage forms rectal suppositories are of the greatest interest. The aim of the study was to carry out a comparative analysis of the effectiveness of local administration of vitamin D3 and 5-aminosalicylic acid in experimental colitis. Materials and methods. Experimental colitis (EC) was modeled with oxazolone solution. Suppositories with vitamin D3 and with 5-ASA were applied per rectum every 12 h. Clinical status (DAI), morphometry, colon tissue injury index (TDI), myeloperoxidase (MPO) and TNF-α expression in the lesion were assessed. Results. In EC, DAI is increases, an ulcerative defect is fixed in the lesion of the colon, TDI, neutrophils (NF), lymphocytes (LC), eosinophils (EF), histiocytes (HC), plasma cells (PC), fibroblasts (FB), MPO and TNF-α expression are increased. Vitamin D3 administration reduces DAI, ulcer defect, TDI, MPO and TNF-α expression, the number of NF, EF, LC and PCs, and increases the number of GCs and FBs. Comparison of vitamin D3 and 5-ASA administration revealed comparable efficacy against DAI. Morphometric evaluation of colorectal lesions showed that under the conditions of vitamin D3 administration, in contrast to 5-ASC, less infiltration, edema, signs of healing and repair of ulcerous defects were fixed earlier in EC; MPO expression increased on the 6th day, TNF-α expression on the 4th day. The TDI index on the 4th and 6th days of EC decreased equally under the conditions of vitamin D3 and 5-ASC application. Discussion. The reduction of clinical severity and morphological signs of damage in the large intestine wall at EC against the background of using rectal suppositories with vitamin D3 could be due to pleiotropic effects of vitamin D3. Conclusion. The effect of vitamin D3 in original rectal suppositories is comparable with local application of 5-ASC at EC, it reduces severity of clinical signs, representation of cells involved in tissue destruction, TNF-α and MPO expression in the colon wall and increases representation of cells mediating reparation.

1400W Prevents Renal Injury in the Renal Cortex But Not in the Medulla in a Murine Model of Ischemia and Reperfusion Injury.

Acute kidney injury (AKI) carries high morbidity and mortality, and the inducible nitric oxide synthase (iNOS) is a potential molecular target to prevent kidney dysfunction. In previous work, we reported that the pharmacological inhibitions of iNOS before ischemia/reperfusion (I/R) attenuate the I/R-induced AKI in mice. Here, we study the iNOS inhibitor 1400W [N-(3-(Aminomethyl)benzyl] acetamide, which has been described to be much more specific to iNOS inhibition than other compounds. We used 30 minutes of bilateral renal ischemia, followed by 24 hours of reperfusion in Balb/c mice. 1400w (10 mg/kg i.p) was applied before I/R injury. We measured the expression of elements associated with kidney injury, inflammation, macrophage polarization, mesenchymal transition, and nephrogenic genes by qRT-PCR in the renal cortex and medulla. The Periodic Acid-Schiff (PAS) was used to study the kidney morphology. Remarkably, we found that 1400W affects the renal cortex and medulla in different ways. Thus, in the renal cortex, 1400W prevented the I/R-upregulation of 1. NGAL, Clusterin, and signs of morphological damage; 2. IL-6 and TNF-α; 3. TGF-β; 4. M2(Arg1, Erg2, cMyc) and M1(CD38, Fpr2) macrophage polarization makers; and 5. Vimentin and FGF2 levels but not in the renal medulla. 1400W conferred protection in the kidney cortex compared to the kidney medulla. The present investigation provides relevant information to understand the opportunity to use 1400W as a therapeutic approach in AKI treatment.

Morphology of the submandibular gland’s acini of rats in diabetes mellitus

Aim. The purpose of the study was to determine the morphological changes in seromucous acini of the submandibular gland in experimental rats with diabetes mellitus.Material and methods. The experiment was performed with 1-year-old male Wistar rats. Experimental diabetes mellitus was induced by a single intraperitoneal administration of streptozotocin. Ultrastructural changes in the seromucous cells of the submandibular gland were studied during the 14th, 42nd and 70th days of the experiment.Results. In experimental diabetes mellitus in the seromucous cells of the submandibular gland hypertrophy of the rough endoplasmic reticulum and the Golgi complex; vacuolization of the cytoplasm; a large number of intracellular laminated structures and lysosomes; diffuse homogenization of the matrix, destruction of mitochondrial cristae and vacuolization of mitochondria were observed and the most pronounced on the 14th day. On the 70th day of the experiment the seromucous cells are characterized by the absence of morphological signs of damage and the development of atrophy and it is confirmed by the reduction in cells’ size as well as the normalization of the relative area of secretory granules.Conclusion. The obtained data indicate that the reaction of the cells of seromucous acini to the development of hyperglycemia is typical and nonspecific. Thus, the alternative changes have a pronounced dystrophic character in the early stages and increase to the 42nd day of the experiment. On the 70th day histologic adaptation of the seromucous acini was observed and approved by atrophic changes, decrease of cells’ area and normalization of the relative area of their granules.

New insight in beryllium toxicity excluding exposure to beryllium-containing dust: accumulation patterns, target organs, and elimination.

There is much contradiction between different experimental studies on beryllium (Be) toxicity. The majority of studies focus on occupational pathologies, caused by the exposure to Be dust. However, Be pollution may affect wide population groups through other exposure routes. The discrepancies between experimental studies may be attributed to the lack of adequate Be toxicity model since conventional administration routes are hampered by high acidity and low solubility of Be compounds. This study was aimed to develop a novel way to implement Be toxicity avoiding side effects, related to high acidity or low solubility of Be salts. Intraperitoneal injection of Be-glycine composition (containing BeSO4, glycine, purified water, pH adjusted to 5.5 with NaOH) was tested in the dose range 238-7622 µmolBekg-1 (body weight, b/w) in full-grown Wistar male rats. The model provided reliable uptake of Be from the peritoneum into general circulation for at least 48h. LD50 was found to be 687 µmolBekg-1 (b/w). The established LD50 value differed from previous data on gastrointestinal, intramuscular or intravenous administration of Be compounds. The liver was found to act as a primary elimination route for Be and related to the highest Be content in the animal. However, it had no signs of morphological damage, which was observed only in the testes (deterioration of germinal epithelium). At the same time, the lungs, stated as a primary target tissue for Be in the models of chronic beryllium disease, did not show strong Be accumulation nor morphological changes. Survived animals showed behavioral changes, including increased motor activity and aggressive reactions in some cases, and complete spasticity in other. The obtained data show the applicability of the established modeling protocol and testified for the independence of chronic beryllium disease on Be2+ ion toxicity per se.

Comparison of vascular and non-vascular aquatic plant as indicators of cadmium toxicity

Antioxidative and microscopic responses in non-vascular (moss Taxiphyllum barbieri) and vascular (Ceratophyllum demersum) aquatic plants exposed to short-term (24 h) cadmium (Cd) excess (10 and 100 μM) were compared. Ceratophyllum considerably accumulated Cd but less pronounced symptoms of oxidative stress were detected by confocal microscopy (at the level of general ROS, hydrogen peroxide, hydroxyl radical/peroxynitrite and superoxide) that could be related to enhanced activities of antioxidative enzymes (SOD, CAT, APX). Amounts of ascorbic acid and non-protein thiols were higher in Ceratophyllum than in Taxiphyllum and increased with increasing Cd dose, which may help to better regulate circulation of free metal ions in Ceratophyllum mainly. Besides, it was observed that citric acid increased in Ceratophyllum while malic acid in Taxiphyllum in response to Cd which may also contribute to Cd chelation. Our data indicate that Ceratophyllum is a suitable species for Cd bioaccumulation while Taxiphyllum is more sensitive to Cd excess and thus suitable as indicator species. It was also proven that sensitive microscopic techniques allow the visualization of Cd-induced changes in aquatic plants even after short-term exposure when no morphological signs of damage are visible.

MR T1ρ and T2 of meniscus six months and one year after acute anterior cruciate ligament injury

s / Osteoarthritis and Cartilage 23 (2015) A82eA416 A223 354 MR T1r AND T2 OF MENISCUS SIX MONTHS AND ONE YEAR AFTER ACUTE ANTERIOR CRUCIATE LIGAMENT INJURY A. Wang, F. Su, V. Pedoia, M. Kretzschmar, L. Nardo, T.M. Link, C.B. Ma, X. Li. Univ. of California, San Francisco, San Francisco, CA, USA Purpose: Acute anterior cruciate ligament (ACL) injury, a high-risk factor for post-traumatic osteoarthritis, is often concomitant with meniscal lesions and tears. In our previous cross-sectional study, we found that acute ACL injuries were associated with significantly elevated meniscal T1r and T2 values compared to healthy knees, even in menisci without morphological signs of damage. The goal of this longitudinal study was to evaluate intermediate-term changes in meniscal T1r and T2 quantification in ACL-injured patients six months and one year after ACL reconstruction and to compare these changes to baseline results. Methods: Using a 3T MR scanner, a closed cohort of 39 patients (age 1⁄4 29.4 ± 7.5 years; 16 females) with acute ACL injuries was scanned at an average of 8.4 ± 6.4 weeks post-injury and prior to ACL reconstruction. After ACL reconstruction, follow-up scans of ACL-injured knees were completed at six months and one year after baseline scan. Subjects were categorized by no lateral meniscectomy (n 1⁄4 32) and partial lateral meniscectomy (n 1⁄4 7). Effects of medial meniscectomy were not evaluated due to small sample size (n 1⁄4 2). Imaging protocol included sagittal T2-weighted 3D fast spin-echo (CUBE) images [repetition time (TR)/echo time (TE) 1⁄4 1500/25 ms, field of view (FOV)1⁄4 16 cm, matrix1⁄4 384 x 384, slice thickness1⁄4 1mm, echo train length 1⁄4 50, bandwidth 1⁄4 50 kHz, number of excitations 1⁄4 0.5] and sagittal 3D T1r and T2 quantification sequences [TR/TE 1⁄4 9 ms/min full, FOV1⁄4 14 cm, matrix1⁄4 256 x 128, slice thickness1⁄4 4mm, Views Per Segment 1⁄4 64, time of recovery 1⁄4 1.2 s, spin-lock frequency 1⁄4 500 Hz, ARC phase AF1⁄4 2. TSL1⁄4 0/10/40/80 ms for T1r, and preparation TE1⁄4 0/ 13.7/27.3/54.7 ms for T2]. Menisci were segmented using CUBE images into four sub-compartments: anterior horn of the lateral/medial meniscus (AHLAT/AHMED) and the posterior horn of the lateral/medial meniscus (PHLAT/PHMED). These regions of interest (ROI) were overlaid onto T1r and T2 maps, andmean T1r and T2 values were calculated for each ROI. Paired t-tests were performed when comparing the same cohort at different time points, and unpaired t-tests were performed when comparing patients who had a partial meniscectomy and patients who did not have a meniscectomy. An alpha of less than 0.05 was considered significant. Results: In ACL-injured knees without meniscectomy, T1r values increased significantly from baseline to six months in the AHLAT, AHMED, and PHMED (all p r > -0.46; p r > -0.30; p<0.005). Intraclass correlation coefficients ranged between 0.95-1.00 for the DCE-MRI variables and 0.80-1.00 for the static MRI variables. Conclusions: The results confirm an association between pain and synovitis assessed on both DCEand CE-MRI in obese patients with knee OA. The whole-knee synovitis score on CE-MRI and most of the DCE-MRI variables were also significantly associated with the remaining KOOS items. DCE-MRI analyses were robust and highly reproducible and have the potential to be used to further investigate the role of inflammation and perfusion in knee OA, in a similar way it has been used in inflammatory joint diseases.

Effects of realistically simulated, elevated UV irradiation on photosynthesis and pigment composition of the alpine snow alga Chlamydomonas nivalis and the arctic soil alga Tetracystis sp. (Chlorophyceae)

An indoor sun simulator was used to provide elevated UV-B radiation (280–315 nm) in combination with realistic ratios to PAR (400–700 nm) and UV-A radiation (315–400 nm) in order to test the physiological response of a soil- and snow microalga during a three-day stress scenario, which may occasionally occur in their respective arctic and alpine habitats. Chlamydomonas nivalis and Tetracystis sp. are initial colonizers of harsh habitats like summer snow fields and bare arctic soils. The two species were chosen because of their role as primary successors in places where life is generally limited by extreme climatic and nutritional conditions. The influence of the increased UV-B irradiation (1.43 W m –2 ; control: 0.52 W m –2 ) on photosynthesis and pigment composition was measured. Both species survived this incubation without any morphological signs of damage, but oxygen production was reduced by 20–56%. Under control conditions, the amount of chlorophylls (Chls) and carotenoids (Cars) per dry mass increased after three days due to optimal light conditions. After the same period, the treated samples of the soil alga Tetracystis sp. showed a smaller increase in Chls and primary Cars than the control. However, the production of extraplastidal, secondary Cars was induced. On the contrary, the snow alga C. nivalis already had high amounts of secondary Cars before the experiment, and after exposure, all pigment classes increased more compared to control conditions. The results show that these microalgae can tolerate short episodes of enhanced UV-B radiation. Photosynthesis may be temporally impaired, but the cells respond by the production of secondary Cars, which can shield their chloroplasts against excessive irradiation or quench reactive oxygen species.

Effects of 50 Hz extremely low frequency magnetic field on the morphology and function of boar spermatozoa capacitated in vitro

The aim of this study was to evaluate the effect of an acute exposure to a sinusoidal MF-ELF (50 Hz, 1 mT) on the ability of boar mature spermatozoa to acquire the fertilizing competence in vitro. The spermatozoa exposed during the 4 h of incubation to the MF-ELF were evaluated for morphological (surface morphology and acrosome integrity) and functional parameters (cell viability, motility, induction of acrosomal reaction, AR, and the ability to in vitro fertilize oocytes). In parallel, the intracellular Ca 2+ levels as well as the major mechanisms of Ca 2+ clearance were assessed: 45Ca intakes and intracellular Ca 2+ sequestration by analyzing intracellular Ca 2+ elevation induced by thapsigargin or studying mitochondrial function with Mito-Tracker. The MF-ELF exposure did not affect sperm viability and morphology during the first h of incubation when sperm Ca 2+ homeostasis were already compromised. First of all, MF-ELF treated spermatozoa showed resting intracellular Ca 2+ levels significantly lower than those recorded in controls. This result was dependent on a lower extracellular Ca 2+ intake and from the inhibitory role exerted on both intracellular Ca 2+ storages. As a consequence, after 1 h of incubation MF-ELF exposed cells displayed a reduced motility, a modest reactivity when coincubated with solubilized zonae pellucidae and a reduction in oocyte penetrating ability. After 2 or 4 h of incubation, in addition, signs of morphological damage appeared on plasma membrane and at acrosomal level. In conclusion, MF-ELF influence negatively spermatozoa first by impairing cell Ca 2+ homeostasis then by dramatically affecting sperm morphology and function.

ORGAN SPECIFIC RELATIONSHIP BETWEEN MITOCHONDRIAL FUNCTION AND TISSUE DAMAGE IN A MODEL OF PERITONITIS IN PIGS

Introduction: The aim of this study was further clarification of the impact of mitochondria to multiple organ failure induced by septic shock. Methods: Peritonitis was induced in pigs by inoculating autologue feces pellets suspended in saline. Liver, heart, and kidney withdrawn 7 hours later were used for histological examination and determination of mitochondrial function. Since one of the mechanisms causing necrosis is a decreased energy supply within the cells, in tissue homogenates of the same organs we also determined the rate of mitochondrial respiration in state 3, which reflects the rate of ATP synthesis. Results: No morphological signs of damage were found in the kidney. In contrast, multiple focal necroses were observed in heart and liver. The state 3 respiration rates were significantly increased in kidney of pigs with peritonitis compared to controls with both substrate of complex I (glutamate-malate) and substrate of complex II (succinate). In contrast, the state 3 respiration rates in liver were significantly decreased both with succinate and with glutamate-malate. A similar decrease in state 3 respiration rates was observed in heart but only with substrate of complex I, indicating malfunction of mitochondria in heart is likely due to a defect in complex I. Conclusions: Our data show organ specific relationship between mitochondrial dysfunction and tissue damage. This supports an existing hypothesis that mitochondria are involved as mechanisms of peritonitis-induced tissue damage.

Strenuous exercise aggravates MDMA-induced skeletal muscle damage in mice

The aim of this study was to investigate the influence of ecstasy (MDMA) administration on body temperature and soleus muscle histology in exercised and non-exercised mice. Charles-River mice were distributed into four groups: Control (C), exercise (EX), MDMA treated (M), and M + EX. The treated animals received an i.p. injection (10 mg/kg) of MDMA (saline for C and EX), and the exercise consisted of a 90 min level run at a velocity of 900 m/h, immediately after the MDMA or saline administration. Body temperature was recorded every 30 min via subcutaneous implanted transponder. Animals were sacrificed 1.5, 25.5, and 49.5 h after i.p. injection and the soleus muscles were removed and processed for light and electron microscopy. The MDMA-treated animals showed a significant increase in body temperature (similar in M and M + EX groups), reaching the peak 90 min after i.p. administration; their temperature remained higher than control for more than 5 h. The EX group evidenced a similar and parallel, yet lower temperature increase during exercise and recovery. Morphological signs of damage were rarely encountered in the EX group; they were more pronounced in M group and even aggravated in M + EX group. In conclusion, MDMA and exercise per se increased body temperature but in conjunction did not have a cumulated effect. However, ecstasy and concomitant physical activity might severely accumulate with regard to skeletal muscle toxicity and may lead to rhabdomyolysis.

Enhanced renal cortical vascularization in experimental hypercholesterolemia

Experimental hypercholesterolemia is associated with pro-inflammatory changes and impaired regulation of tissue perfusion, which may lead to neovascularization. However, it is yet unknown whether such changes take place in the kidney. In this study, using a novel three-dimensional (3-D) micro computed-tomography technique we tested the hypothesis that hypercholesterolemia was associated with increased microvascular density in the renal cortex. Kidneys were excised from pigs after 12 weeks of either a normal (N = 6) or high cholesterol (HC; N = 5) diet, histology slides processed, and a segmental renal artery injected with a radio-opaque intravascular silicone polymer. Renal samples were scanned with micro computed-tomography, transverse and three-dimensional images were reconstructed, and microvessels (80 to 360 microm in diameter) counted in situ. Serum cholesterol levels were significantly higher in hypercholesterolemic compared to normal pigs (383 +/- 76 vs. 81 +/- 7 mg/dL, P < 0.01), and microvascular spatial density was significantly higher in their inner and middle renal cortex (189 +/- 7 vs. 126 +/- 6 microvessels/cm2, P < 0.0001). Hypercholesterolemic kidneys also showed mild interstitial mononuclear infiltration and heavier immunostaining of vascular endothelial growth factor, but no other signs of morphological damage. These results demonstrate that early diet-induced hypercholesterolemia is associated with increased microvascular density in the renal cortex, which precedes signs of overt renal morphological damage. These alterations may potentially affect regulation and/or spatial distribution of intrarenal blood flow in hypercholesterolemia, and may participate in renal disease progression.

Hemorrhagic shock-induced changes in the cathepsin D activity in the intestinal wall and blood serum in rats.

Hemorrhagic shock causes release of lysosomal proteolytic enzymes which contribute to intestinal wall destruction and can be moved into the circulation as well as into the gut lumen. The aim of the study was to examine the activity of cathepsin D in relation to the intestinal wall injury after 60 minutes of untreated hemorrhagic shock in rats. The total cathepsin D activity was investigated in duodenum, jejunum, ileum, cecum and colon, as well as in systemic and mesenteric blood serum, and the biochemical results were compared with morphological changes in the respective segments including immunohistochemical expression of cathepsin D. We found an increase in cathepsin D activity in duodenum and significant decrease in other parts of the gut in shocked rats. The enzyme activity increased also in blood serum, especially systemic (p < 0.05) and insignificantly in mesenteric blood. However, sham-operated animals (one-side carotid artery occlusion) revealed a significant increase in cathepsin D activity measured in mesenteric blood. The shock resulted in lowering protein concentration in the intestinal wall and its increase in mesenteric blood. The contents of peptides and amino nitrogen, as potential proteolytic reaction products, changed in different ways in various segments of intestine. Morphologically, the most intensive destruction was observed in ileum, duodenum and jejunum. Lifting of epithelial layer from lamina propria was the most frequently observed lesion of the intestinal wall after 60 minutes of shock. More advanced lesions, such as denuded mucosa with disintegration of lamina propria, occurred rarely and were not observed in colon and rectum. By means of polyclonal antibodies against cathepsin D, we found that the strong expression of this enzyme was in epithelial layer--the part of intestinal wall which was partially detached into gut lumen due to hemorrhagic shock. The changes of cathepsin D activity after 60 minutes of hemorrhagic shock were correlated with signs of morphological damage to the intestinal wall. Cathepsin D liberation in the intestinal wall during shock indicates the lysosomal membranes impairment and can confirm involvement of proteases in the damage to the intestinal tissue. We conclude that liberation of intestinal cathepsin D is an early phenomenon during hemorrhagic shock which may contribute to the local wall disintegration and activation of systemic inflammatory response.

Histological changes in human breast cancer after interstitial irradiation with a pulsed Nd-YAG laser

This is a clinical study of the histological changes induced in human primary breast cancer by single-session pre-operative interstitial irradiation using a medium-power Nd-YAG laser (1064 nm, 1–6 W, 20 pulse s-1, 100 Μs). Changes were studied in 15 tumours resected at an interval of 1–11 days after laser treatment, and in four biopsy samples from three tumours treated conservatively and biopsied for suspected recurrence 1–3 months after laser treatment. All foci of laser-induced destruction consisted of a sphere-shaped infarction 0.5–2.5 cm in diameter which enclosed a small evaporation cavity within carbonized walls. Vapour separation occurred in two tumours and gaseous rupture was seen in one tumour. Extensive vascular damage was seen inside the damaged area; damage to cancer cells was manifested by diminished size, vacuolization, cytoplasmic turbidity, pyknosis, disruption of the nuclear membrane and nuclear homogeneity. No clear morphological signs of damage could be seen in a significant percentage of cancer cells on short-term inspection (35–80%). Long-term histological study revealed a central necrotic area of diameter 1–1.2 cm in the laser-treated tumours, containing no viable cancer cells. In inadequately treated carcinomas, regrowth of tumour was seen at the periphery of this zone.

Selective neurotoxicity of ruthenium red in primary cultures

The inorganic dye ruthenium red (RuR) has been shown to be neurotoxic in vivo when injected intracerebrally. In this work the toxicity of RuR was compared in primary cultures of rat cortical neurons, cerebellar granule neurons and cerebellar astroglia. Microscopic examination of the cultures revealed that RuR penetrates the somata of both types of neurons used and produces vacuolization and loss and fragmentation of neurites. In contrast, no RuR was seen inside cultured astrocytes and no morphological signs of damage were observed in these cells. RuR toxicity was also assessed by immunocytochemistry of alpha-tubulin and by biochemical measurement of the reduction of (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) by the cultured cells. The morphological alterations in the neurons were closely correlated with loss of tubulin immunoreactivity and particularly with a notable decrement in the ability to reduce MTT. Using the latter parameter, it was found that neuronal damage was independent of the age of the cultures, augmented progressively with time of incubation with RuR, from 8 to 24 h, and showed a clear dose-response curve from 20 to 100 microM RuR. Astrocytes showed only a slight decrease in MTT reduction after 24 h of incubation with 100 microM RuR. It is concluded that RuR seems to be toxic for neurons but not for astroglia, and that this selectivity is probably related to the ability of the neurons to internalize the dye. The possible mechanisms of RuR penetration and neuronal damage are discussed.

Cell vitality in cartilage tissue culture following excimer laser radiation: An in vitro examination

Excimer laser is used for cartilage debridement, although the resulting cell damage is yet unclear. For examination of cartilage survival after treatment, we used short-term tissue cultures of human joint cartilage. Specimens were treated with a XeCl-Excimer laser using different laser parameters, pulse energies, and repetition rates. Following treatment, discs were cultured for 8 days prior to examination. In contrast to the 20 microns damage zone as instant visible effect in histomorphologic examinations, we found a 0.3 mm zone in which approximately 50% of cartilage cells had morphological signs of damage on light microscopic examinations. Autoradiography revealed that cartilage cells in an 0.5-0.7 mm area surrounding the laser craters had no collagen synthesis. This examination indicates that cell damage of excimer laser is higher than expected from prior studies.

Prolonged exposure of human pancreatic islets to high glucose concentrations in vitro impairs the beta-cell function.

The aim of the present study was to clarify whether prolonged in vitro exposure of human pancreatic islets to high glucose concentrations impairs the function of these cells. For this purpose, islets isolated from adult cadaveric organ donors were cultured for seven days in RPMI 1640 medium supplemented with 10% fetal calf serum and containing either 5.6, 11, or 28 mM glucose. There was no glucose-induced decrease in islet DNA content or signs of morphological damage. However, islets cultured at 11 or 28 mM glucose showed a 45 or 60% decrease in insulin content, as compared to islets cultured at 5.6 mM glucose. Moreover, when such islets were submitted to a 60-min stimulation with a low (1.7 mM) followed by a high (16.7 mM) concentration of glucose, the islets cultured at 5.6 mM glucose showed a higher insulin response to glucose than those of the two other groups. Islets cultured at the two higher glucose concentrations showed increased rates of insulin release in the presence of low glucose, and a failure to enhance further the release in response to an elevated glucose level. Islets cultured at 28 mM glucose showed an absolute decrease in insulin release after stimulation with 16.7 mM glucose, as compared to islets cultured at 5.6 mM glucose. The rates of glucose oxidation, proinsulin biosynthesis, and total protein biosynthesis were similar in islets cultured at 5.6 or 11 mM glucose, but they were decreased in islets cultured at 28 mM glucose. These combined results suggest that lasting exposure to high glucose concentrations impairs the function of human pancreatic islets.

Aspects of neural plasticity in the central nervous system—V. Studies on a model of transient forebrain ischemia in male Sprague-Dawley rats

A morphological and functional characterization of the four-vessel occlusion model of transient (30 min) forebrain ischemia has been carried out. The rats were classified as fully ischemic when an isoelectric pattern of electroencephalographic activity was present within 5 min of the occlusion of carotid arteries. Otherwise they were considered as partially ischemic rats. The modifications of cerebral blood content during and after the ischemic insult were assessed by a histochemical method which visualizes red blood cells in cerebral vessels. The periods of increase and decrease of red blood cell content were found to correspond to previous reports of post-ischemic hyper- and hypoperfusion. Neuronal damage was assessed by a quantitative analysis of Nissl stained preparations of cingulate cortex, dorsal hippocampus and striatum. The signs of morphological damage were quantified by means of computer-assisted image analysis of Nissl preparations. The highest vulnerability to the ischemic insult was demonstrated in the pyramidal layer of the hippocampal CA1 field and in the lateral striatum. Arterial blood pressure measurements were performed during the ischemic and post-ischemic periods, demonstrating a peak increase of arterial blood pressure within 2 min after carotid artery occlusion, followed by a slow decrease towards basal levels during the ischemic period and a full recovery within 15 min of reperfusion. Ischemic rats were tested in a neurological test battery and in a passive avoidance task. While a full recovery of the relatively simple tasks of the neurological test battery was attained within 14 days of reperfusion, a highly significant impairment of passive avoidance behavior was still present 15 days after the ischemic insult. Finally, a discriminant analysis was applied to separate, on the basis of non-invasive techniques (neurological tests and hot plate), the group of completely ischemic rats from that of partially ischemic rats.

Electrical Activity of the Ganglion Cells in Irradiated Retinas

The time course of the impairment of both photic and spontaneous excitation of the retinal ganglion cells of cats is described for the 2 weeks following -y-irradiation (4200 rad) and is related to morphological signs of damage. Irradiation resulted in damage to the receptor cells. This did not affect the spontaneous activity of the ganglion cells during the following first eek, but later their firing patterns and firing rates were clearly changed. The first week was characterized morphologically by necrosis of the receptor cells. During the subsequent period vascular changes and degeneration of the neural retina became noticeable.