Excessive hexosamines block the neuroprotective effect of insulin and induce apoptosis in retinal neurons

In addition to microvascular abnormalities, neuronal apoptosis occurs early in diabetic retinopathy, but the mechanism is unknown. Insulin may act as a neurotrophic factor in the retina via the phosphoinositide 3-kinase/Akt pathway. Excessive glucose flux through the hexosamine biosynthetic pathway (HBP) is implicated in the development of insulin resistance in peripheral tissues and diabetic complications such as nephropathy. We tested whether increased glucose flux through the HBP perturbs insulin action and induces apoptosis in retinal neuronal cells. Exposure of R28 cells, a model of retinal neurons, to 20 mm glucose for 24 h attenuated the ability of 10 nm insulin to rescue them from serum deprivation-induced apoptosis and to phosphorylate Akt compared with 5 mm glucose. Glucosamine not only impaired the neuroprotective effect of insulin but also induced apoptosis in R28 cells in a dose-dependent fashion. UDP-N-acetylhexosamines (UDP-HexNAc), end products of the HBP, were increased approximately 2- and 15-fold after a 24-h incubation in 20 mm glucose and 1.5 mm glucosamine, respectively. Azaserine, a glutamine:fructose-6-phosphate amidotransferase inhibitor, reversed the effect of 20 mm glucose, but not that of 1.5 mm glucosamine, on attenuation of the ability of insulin to promote cell survival and phosphorylate Akt as well as accumulation of UDP-HexNAc. Glucosamine also impaired insulin receptor processing in a dose-dependent manner but did not decrease ATP content. By contrast, in L6 muscle cells, glucosamine impaired insulin receptor processing but did not induce apoptosis. These results suggest that the excessive glucose flux through the HBP may direct retinal neurons to undergo apoptosis in a bimodal fashion; i.e. via perturbation of the neuroprotective effect of insulin mediated by Akt and via induction of apoptosis possibly by altered glycosylation of proteins. The HBP may be involved in retinal neurodegeneration in diabetes.

DNA sequence and comparison of virulence plasmids from Rhodococcus equi ATCC 33701 and 103

The virulence plasmids of the equine virulent strains Rhodococcus equi ATCC 33701 and 103 were sequenced, and their genetic structure was analyzed. p33701 was 80,610 bp in length, and p103 was 1 bp shorter; their sequences were virtually identical. The plasmids contained 64 open reading frames (ORFs), 22 of which were homologous with genes of known function and 3 of which were homologous with putative genes of unknown function in other species. Putative functions were assigned to five ORFs based on protein family characteristics. The most striking feature of the virulence plasmids was the presence of a 27,536-bp pathogenicity island containing seven virulence-associated protein (vap) genes, including vapA. These vap genes have extensive homology to vapA, which encodes a thermoregulated and surface-expressed protein. The pathogenicity island contained a LysR family transcriptional regulator and a two-component response regulator upstream of six of the vap genes. The vap genes were present as a cluster of three (vapA, vapC, and vapD), as a pair (vapE and vapF), or individually (vapG; vapH). A region of extensive direct repeats of unknown function, possibly associated with thermoregulation, was present immediately upstream of the clustered and the paired genes but not the individual vap genes. There was extensive homology among the C-terminal halves of all vap genes but not generally among the N-terminal halves. The remainder of the plasmid consisted of a large region which appears to be associated with conjugation functions and a large region which appears to be associated with replication and partitioning functions.

Disruption of the epilepsy KCNQ2 gene results in neural hyperexcitability

Benign familial neonatal convulsion (BFNC) is a common idiopathic epilepsy with autosomal dominant inheritance. Recently, two novel voltage-dependent potassium channel genes, KCNQ2 and KCNQ3, were identified by positional cloning as being responsible for BFNC. Heterotetramers of the products of these genes form M-channels and regulate the threshold of electrical excitability of neurons. We disrupted the mouse KCNQ2 gene via gene targeting to study the relationship between KCNQ2 and epilepsy. Homozygous pups (KCNQ2 -/-) died within a few hours after birth owing to pulmonary atelectasis that was not due to the status of epileptic seizures, although their development was morphologically normal. Heterozygous mice had decreased expression of KCNQ2 and showed hypersensitivity to pentylenetetrazole, an inducer of seizure. These data indicate that the decreased expression of KCNQ2 might cause a hyperexcitability of the CNS, which accounts for the mechanism of BFNC.

Three histidine residues of amyloid-beta peptide control the redox activity of copper and iron

Zinc, iron and copper are concentrated in senile plaques of Alzheimer disease. Copper and iron catalyze the Fenton-Haber-Weiss reaction, which likely contributes to oxidative stress in neuronal cells. In this study, we found that ascorbate oxidase activity and the intensity of ascorbate radicals measured using ESR spectroscopy, generated by free Cu(II), was decreased in the presence of amyloid-beta (Abeta), the major component of senile plaques. Specifically, the ascorbate oxidase activity was strongly inhibited (85% decrease) in the presence of Abeta1-16 or Abeta1-42, whereas it was only slightly inhibited in the presence of Abeta1-12 or Abeta25-35 (<20% inhibition). Ascorbate-dependent hydroxyl radical generation by free Cu(II) decreased in the presence of Abeta in the identical order of Abeta1-42, Abeta1-16 > Abeta1-12 and was abolished in the presence of 2-fold molar excess glycylhystidyllysine (GHK). Ascorbate oxidase activity and ascorbate-dependent hydroxyl radical generation by free Fe(III) were inhibited by Abeta1-42, Abeta1-16, and Abeta1-12. Although Cu(II)-Abeta shows a significant SOD-like activity, the rate constant for the reaction of superoxide with Cu(II)-Abeta was much slower than that with SOD. Overall, our results suggest that His6, His13, and His14 residues of Abeta1-42 control the redox activity of transition metals present in senile plaques.

Hyaluronan stimulates corneal epithelial migration

Hyaluronan (hyaluronic acid), well-known for its viscoelastic properties, is also recognized as a biological signal to cells. Using organ cultures of the rabbit cornea, we investigated the effects of hyaluronan on the migration of corneal epithelium. The addition of hyaluronan to the culture medium increased the length of the path of the corneal epithelial layer in a dose-dependent fashion. Other glycosaminoglycans (chondroitin, chondroitin sulphate, keratan sulphate and heparan sulphate) were also tried, but only hyaluronan exhibited a stimulatory effect on corneal epithelial migration. The effects of hyaluronan and fibronectin or epidermal growth factor (EGF) were additive; the addition of antisera against fibronectin or against EGF did not alter the stimulatory effect of hyaluronan. These results demonstrate that hyaluronan stimulates corneal epithelial migration by mechanism(s) different from those of fibronectin and EGF.

Progressively developed myocardial apoptotic cell death during late phase of reperfusion

Myocardial apoptosis is primarily triggered during reperfusion (R). The aim of this study was to test the hypothesis that R-induced apoptosis develops progressively during the late phase of R, and that R-induced apoptosis is associated with changes in expression of anti- and pro-apoptotic proteins and infiltrated inflammatory cells. Thirty-one dogs were subjected to 60 min of left anterior descending coronary occlusion followed by 6, 24, 48, and 72 h R, respectively. There was no group difference in collateral blood flow, measured by colored microspheres during ischemia. Necrotic cell death (TTC staining) was significantly increased during R, starting at 27 +/- 2% at 6 h R and increasing to 41 +/- 2% at 24 h R. There was no further change at 48 (37 +/- 3%) and 72 (36 +/- 6%) h R, respectively. TUNEL positive cells (% total normal nuclei) in the peri-necrotic zone progressively increased from 6 (26 +/- 2) to 24 (38 +/- 1), 48 (48 +/- 3) and 72 (59 +/- 4) h R, respectively. The number of detected TUNEL positive cells at these time points was consistent with an increased intensity of DNA ladders, identified by agarose gel electrophoresis. Compared with normal tissue, western blot analysis showed persistent reduction in expression of anti-apoptotic protein Bcl-2 from 6 (16 +/- 0.8%) to 72 h R (78 +/- 2%), and increase in expression of pro-apoptotic proteins including Bax from 6 (30 +/- 3%) to 72 h R (66 +/- 3%), and p53 from 6 (12 +/- 1%) to 72 h R (91 +/- 2%), respectively. Immunohistochemical staining revealed that infiltrated neutrophils (mm(2) myocardium) were significantly correlated with development of necrotic and apoptotic cell death from 6 to 24 h R, respectively (P < 0.05), while large macrophage infiltration seen during 48 to 72 h R were correlated with apoptotic cell death (P < 0.05). These results indicate that 1) necrosis peaked at 24 h R when apoptosis was still progressively developing during later R; 2) changes in Bcl-2 family and p53 proteins may participate in R-induced myocardial apoptosis; 3) inflammatory cells may play a role in triggering cell death during R. P < 0.05 vs. normal nuclei and tissue; P < 0.01 vs. 6 h R.

Diversity and plasticity of sex determination and differentiation in fishes

Among vertebrates, fishes show an exceptional range of reproductive strategies regarding the expression of their sexuality. Fish sexualities were categorized into gonochorism, synchronous/sequential hermaphrodite, or unisexual reproduction. In gonochoristic fishes, sex is determined genetically or by environmental factors. After sex determination, the gonads are differentiated into ovary or testis, with the sex remaining fixed for the entire life cycle. In contrast, some sequential hermaphrodite fishes can change their sex from male to female (protandrous), female to male (protogynous), or serially (bi-directional sex change) in their life cycle. In many cases, sex change is cued by social factors such as the disappearance of a male or female from a group. This unique diversity in fishes provides an ideal animal model to investigate sex determination and differentiation in vertebrates. This review first discusses genetic-orientated sex determination mechanisms. Then, we address the gonadal sex differentiation process in a gonochoristic fish, using an example of the Nile tilapia. Finally, we discuss various types of sex change that occur in hermaphrodite fishes.

A novel antigenic variant of Canine parvovirus from a Vietnamese dog

Nine isolates of Canine parvovirus (CPV) were obtained from Vietnamese dogs and cats. One canine isolate showed a unique antigenic property which indicates a novel antigenic variant of CPV-2b when examined with hemagglutination inhibition tests using our monoclonal antibodies, 21C3 and 19D7, which were recently developed. This isolate had an amino acid substitution of residue 426, Asp to Glu, and the same substitution has recently been found in CPV from Italian dogs. This study first showed that such substitution caused an antigenic difference demonstrable by monoclonal antibodies and that a similar evolution may have occurred in CPV in Vietnam.

Pruritogenic mediators in psoriasis vulgaris: comparative evaluation of itch-associated cutaneous factors

BACKGROUND

Although some patients with psoriasis vulgaris also complain of severe pruritus, the data available regarding pruritus in psoriasis are sparse.

OBJECTIVES

To clarify the mechanism and mediators involved in the pruritus of psoriasis vulgaris, we compared itch-associated factors in lesional skin from psoriatic patients vs. skin without pruritus quantitatively using a panel of histological and immunohistological parameters.

PATIENTS AND METHODS

Biopsied specimens were obtained from 38 patients with psoriasis vulgaris who were divided into two groups according to the presence or absence of pruritus.

RESULTS

When compared with psoriatic patients devoid of pruritus, lesional skin from patients with pruritus showed the following characteristic features: (i) a rich innervation both in the epidermis and in the papillary dermis; (ii) an increase in neuropeptide substance P-containing nerve fibres in perivascular areas; (iii) decreased expression of neutral endopeptidase in the epidermal basal layer as well as in the endothelia of blood vessels; (iv) many mast cells showing degranulating processes in the papillary dermis; (v) a strong immunoreactivity for nerve growth factor (NGF) throughout the entire epidermis and an increased NGF content in lesional skin homogenates; (vi) an increase in the expression of high-affinity receptors for NGF (Trk A) in basal keratinocytes and in dermal nerves; (vii) an increased population of interleukin-2-immunoreactive lymphocytes; and (viii) a strong expression of E-selectin on vascular endothelial cells. A significant correlation was observed between the severity of pruritus and protein gene product 9.5-immunoreactive intraepidermal nerve fibres, NGF-immunoreactive keratinocytes, expression of Trk A in the epidermis and the density of immunoreactive vessels for E-selectin. These findings indicate that possible pruritogenic mediators in psoriatic lesional skin are neurogenic factors including innervation, neuropeptide substance P, neuropeptide-degrading enzymes and NGF, activated mast cells, one or more cytokines and endothelial-leucocyte adhesion molecules.

CONCLUSIONS

These data document for the first time itch-related local markers in psoriasis, and suggest complex and multifactorial mechanisms of pruritus in the disease. These results provide the groundwork for further studies to evaluate the efficacy of antipruritic treatment for psoriatic patients.

Peripheral analgesic action of clonidine: mediation by release of endogenous enkephalin-like substances

Clonidine analgesia was tested on the hyperalgesia induced by intraplantar injection of prostaglandin E2 or carrageenin. The antinociceptive effect of clonidine was dose-dependent and was abolished by local administration of the selective alpha 2-adrenoceptor blocker, yohimbine or of the opioid antagonists naloxone or quaternary nalorphine. St-91, a clonidine analog which does not cross the blood-brain barrier also promoted significant antinociception. Repeated administration of drugs possessing a central mechanism of analgesic action leads to the development of tolerance in this test. Significant analgesic tolerance was observed following repeated (5 days) morphine (8 mg/kg) or high doses of clonidine (0.5 mg/kg). In contrast, no tolerance was detected to the analgesic effect of low doses of clonidine (0.15 mg/kg) or of St-91 (0.5 mg/kg). These results suggest that, in addition to its central analgesic action, clonidine can induce peripheral antinociception by an alpha 2-adrenoceptor-mediated local release of enkephalin-like substances.

The cardiovascular effects and implications of peroxynitrite

Nitric oxide is an endogenous autacoid produced primarily by the vascular endothelium. Under basal conditions, nitric oxide undergoes a rapid biradical reaction with superoxide anions to form peroxynitrite. This reaction, and hence the formation of peroxynitrite is augmented in inflammatory-like conditions such as ischemia-reperfusion injury when both substrates are present in high concentrations. Peroxynitrite has been implicated as a physiologically active toxic metabolite of nitric oxide leading to vascular and myocardial dysfunction. Recent evidence, however, has suggested that peroxynitrite may actually have beneficial properties under in vivo biological conditions when thiol-containing agents (glutathione, albumin, cysteine) agents are available to convert the peroxynitrite anion to nitrosothiols and related products demonstrating antineutrophil and cardioprotective properties. The dichotomy of physiologically relevant properties of peroxynitrite has important clinical applications with respect to nitric oxide therapy for cardiac, vascular, cerebral and pulmonary disease states. This review summarizes the biological properties of peroxynitrite relevant to the cardiovascular system.

Immunotherapy of recurrent genital herpes with recombinant herpes simplex virus type 2 glycoproteins D and B: results of a placebo-controlled vaccine trial

To determine the safety, immunogenicity, and efficacy of a recombinant herpes simplex virus type 2 glycoprotein D and B vaccine in the treatment of recurrent genital herpes, a randomized, placebo-controlled trial was held at two referral centers. Healthy patients with 4-14 recurrences per year received injections of both glycoproteins in MF59 adjuvant or of MF59 alone at 0, 2, 12, and 14 months. For 18 study months, the rate and number of recurrences, the duration and severity of the first confirmed recurrence, vaccine immunogenicity, and rates of local and systemic reactions were determined. The monthly rate of recurrences was not significantly improved, but the duration and severity of the first study outbreak was reduced significantly by vaccination. Glycoprotein-specific and neutralizing antibodies were boosted by vaccination for the duration of the study. This vaccine is safe and immunogenic and ameliorated an observed first postvaccination genital recurrence, but it does not reduce recurrence frequency.

gyrA and gyrB mutations in quinolone-resistant strains of Escherichia coli

The proportion of gyrA and gyrB mutations in quinolone-resistant Escherichia coli strains was examined by introducing cloned wild-type gyrA and gyrB genes. In 25 spontaneous mutants of strain KL16, 13 had gyrA and 12 had gyrB mutations. In eight clinical isolates, five had gyrA mutations and one had a gyrB mutation; mutations in two isolates remained unidentified.

A peripheral sympathetic component in inflammatory hyperalgesia

Non-steroidal anti-inflammatory drugs (NSAID) only partially inhibit the hyperalgesia in the inflammation induced by carrageenin in the hind rat paw, one of the most frequently used nociceptive tests. We now report that either the guanethidine depletion of peripheral sympathomimetic amines or the treatment with adrenoceptor antagonists (beta-blockers) and a specific dopamine (DA)-1 antagonist (SCH 23390) significantly reduced carrageenin hyperalgesia. These antagonists also abolished the rat paw hyperalgesia induced by several sympathomimetic amines as well as that induced by a selective DA-1 agonist, SKF 38393. Blockade of uptake-1 by cocaine potentiated the hyperalgesia induced by carrageenin and sympathomimetic amines. We conclude that there is a sympathetic component, possibly mediated by a DA-1 type receptor in carrageenin-induced hyperalgesia. This component may predominate in certain types of pain not sensitive to NSAID. If so, selective peripheral DA-1 antagonists could be developed as a novel class of analgesics.

Coordinate induction of peroxisomal acyl-CoA oxidase and UCP-3 by dietary fish oil: a mechanism for decreased body fat deposition

Rats fed dietary fats rich in 20- and 22-carbon polyenoic fatty acids deposit less fat and expend more energy at rest than rats fed other types of fats. We hypothesized that this decrease in energetic efficiency was the product of: (a) enhanced peroxisomal fatty acid oxidation and/or (b) the up-regulation of genes encoding proteins that were involved with enhanced heat production, i.e. mitochondrial uncoupling proteins (UCP-2, UCP-3) and peroxisomal fatty acid oxidation proteins. Two groups of male Fisher 344 rats 3-4 week old (n=5 per group) were pair fed for 6 weeks a diet containing 40% of its energy fat derived from either fish oil or corn oil. Epididymal fat pads from rats fed the fish oil diet weighed 25% (P < 0.05) less than those found in rats fed corn oil. The decrease in fat deposition associated with fish oil ingestion was accompanied by a significant increase in the abundance of skeletal muscle UCP-3 mRNA. The level of UCP-2 mRNA skeletal muscle was unaffected by the type of dietary oil, but the abundance of UCP-2 mRNA in the liver and heart were significantly lower (P < 0.05) in rats fed fish oil than in rats fed corn oil. In addition to inducing UCP-3 expression, dietary fish oil induced peroxisomal acyl-CoA oxidase gene expression 2-3 fold in liver, skeletal muscle and heart. These data support the hypothesis that dietary fish oil reduces fat deposition by increasing the expression of mitochondrial uncoupling proteins and increasing fatty acid oxidation by the less efficient peroxisomal pathway.

Priming of the neutrophil respiratory burst involves p38 mitogen-activated protein kinase-dependent exocytosis of flavocytochrome b558-containing granules

The respiratory burst of human neutrophils is primed by a number of pro-inflammatory stimuli, including tumor necrosis factor-alpha (TNFalpha) and lipopolysaccharide (LPS); however, the mechanism of priming remains unknown. LPS has been shown previously to increase membrane expression of flavocytochrome b(558), a component of the NADPH oxidase. This study shows that TNFalpha also increases membrane expression of flavocytochrome b(558). Mitogen-activated protein kinase (MAPK) modules have been implicated in the action of priming agents. Pharmacologic inhibitors of MAPKs, SB203580 and PD098059, revealed that priming of the respiratory burst and up-regulation of flavocytochrome b(558) are dependent on p38 MAPK but not on extracellular-signal regulated kinase (ERK). TNFalpha and LPS primed respiratory burst activity and increased membrane expression of CD35 and CD66b, specific markers of secretory vesicles and specific granules that contain flavocytochrome b(558), with similar time courses and concentration dependences. These processes also required p38 MAPK but were independent of ERK. TNFalpha failed to prime respiratory burst activity or to increase membrane CD35 expression in enucleated neutrophil cytoplasts. These data suggest that one mechanism by which TNFalpha and LPS prime neutrophil respiratory burst activity is by increasing membrane expression of flavocytochrome b(558) through exocytosis of intracellular granules in a process regulated by p38 MAPK.

Effect of IFN-gamma on the immune response in vivo and on gene expression in vitro

T lymphocytes produce a variety of immunoregulatory molecules including gamma interferon (IFN-gamma) and antigen-specific suppressor and enhancer factors. During our studies of active substances obtained from cloned T-cell lines, we observed that certain fractions administered to mice resulted in enhancement of immune responses. Preliminary characterization of the substance suggested that it could be IFN-gamma and we therefore undertook a study of the action of IFN-gamma produced by recombinant DNA methodology on immune responses. We found that for several antigens, administration of IFN-gamma to mice leads to two- to five-fold enhancement of antibody formation provided that the IFN-gamma and antigen are administered together. The effect was dose dependent, giving a maximal response at 500-600 anti-viral units per mouse. Preliminary studies suggest that the macrophage may be the target of IFN-gamma action. Addition of IFN-gamma to cultures of a macrophage cell line leads to a greater than 10-fold increase in the level of RNA coding for I-region-encoded cell surface molecules.

What causes alopecia areata?

The pathobiology of alopecia areata (AA), one of the most frequent autoimmune diseases and a major unsolved clinical problem, has intrigued dermatologists, hair biologists and immunologists for decades. Simultaneously, both affected patients and the physicians who take care of them are increasingly frustrated that there is still no fully satisfactory treatment. Much of this frustration results from the fact that the pathobiology of AA remains unclear, and no single AA pathogenesis concept can claim to be universally accepted. In fact, some investigators still harbour doubts whether this even is an autoimmune disease, and the relative importance of CD8(+) T cells, CD4(+) T cells and NKGD2(+) NK or NKT cells and the exact role of genetic factors in AA pathogenesis remain bones of contention. Also, is AA one disease, a spectrum of distinct disease entities or only a response pattern of normal hair follicles to immunologically mediated damage? During the past decade, substantial progress has been made in basic AA-related research, in the development of new models for translationally relevant AA research and in the identification of new therapeutic agents and targets for future AA management. This calls for a re-evaluation and public debate of currently prevalent AA pathobiology concepts. The present Controversies feature takes on this challenge, hoping to attract more skin biologists, immunologists and professional autoimmunity experts to this biologically fascinating and clinically important model disease.

Synergistic effects of substance P with insulin-like growth factor-1 on epithelial migration of the cornea

We find that substance P (SP) and insulin-like growth factor-1 (IGF-1) demonstrate a synergistic effect on the stimulation of rabbit corneal epithelial migration in an organ culture. The addition of either SP or IGF-1 alone did not affect epithelial migration, while the combination of SP and IGF-1 stimulated epithelial migration in a dose-dependent fashion. The synergistic effects of SP and IGF-1 on corneal epithelial migration were nulled by the addition of a SP antagonist or enkephalinase. Among neurotransmitters (vasoactive intestinal peptide, calcitonin gene-related peptide, acethylcholine chloride, norepinephrine, serotonin) or tachykinins (neurokinin A, neurokinin B, kassinin, eledoisin, physalaemin), only SP demonstrated a synergistic effect with IGF-1 on cellular migration. In contrast, the combination of SP and IGF-1 did not affect the incorporation of 3H-thymidine into corneal epithelial cells. The attachment of the corneal epithelial cells to fibronectin, collagen type IV, and laminin matrices increased after treatment of the cells with SP and IGF-1, but SP or IGF-1 by themselves did not affect the attachment of the cells to these extracellular matrix proteins. An identical synergistic effect on corneal epithelial migration was observed when an NK-1 receptor agonist was used in place of SP, suggesting the synergistic effect of SP and IGF-1 might be mediated through the NK-1 receptor system. These results suggest that the maintenance of the normal integrity of the corneal epithelium might be regulated by both humoral and neural factors.

Hypothermic circulatory arrest causes multisystem vascular endothelial dysfunction and apoptosis

BACKGROUND

Multiple organ failure after deep hypothermic circulatory arrest (DHCA) may occur secondary to endothelial dysfunction and apoptosis. We sought to determine if DHCA causes endothelial dysfunction and apoptosis in brain, kidney, lungs, and other tissues.

METHODS

Anesthetized pigs on cardiopulmonary bypass were: (1) cooled to 18 degrees C, and had their circulation arrested (60 minutes) and reperfused at 37 degrees C for 90 minutes (DHCA, n = 8); or (2) time-matched normothermic controls on bypass (CPB, n = 6). Endothelial function in cerebral, pulmonary, and renal vessels was assessed by vasorelaxation responses to endothelial-specific bradykinin (BK) or acetylcholine (ACh), and smooth muscle-specific nitroprusside.

RESULTS

In vivo transcranial vasorelaxation responses to ACh were similar between the two groups. In small-caliber cerebral arteries, endothelial relaxation (BK) was impaired in CPB vs DHCA (maximal 55% +/- 2% [p < 0.05] vs 100% +/- 6%). Pulmonary artery ACh responses were comparable between CPB (110% +/- 10%) and DHCA (83% +/- 6%), but responses in pulmonary vein were impaired in DHCA (109% +/- 3%, p < 0.05) relative to CPB (137% +/- 6%). In renal arteries, endothelial (ACh) responses were impaired in DHCA (71% +/- 13%) relative to CPB (129% +/- 14%). Apoptosis (DNA laddering) occurred primarily in duodenal tissue, with a greater frequency in DHCA (56%, p < 0.05) compared with normothermic CPB (17%) and nonbypass controls (0%).

CONCLUSIONS

DHCA is associated with endothelial dysfunction in cerebral microvessels but not in the in vivo transcranial vasculature; in addition, endothelial dysfunction was noted in large-caliber renal arteries and pulmonary veins. DHCA is also associated with duodenal apoptosis. Vascular endothelial dysfunction and apoptosis may be involved in the pathophysiology of multisystem organ failure after DHCA.

Analysis of prognostic and survival factors related to treatment of low-grade astrocytomas in adults

Prognostic factors for low-grade astrocytomas have been proposed, but optimal treatment remains controversial. Eighty-eight consecutive adult patients with supratentorial low-grade astrocytomas were retrospectively reviewed to determine specific factors influencing outcome. All underwent craniotomy (43 radical resections, 45 nonradical resections). Sex, age at diagnosis, preoperative Karnofsky performance status (KPS), tumor location, estimated extent of resection, radiation, chemotherapy, histological type, p53 status, MIB-1 staining and the apoptotic index were assessed as parameters for prognostic significance. KPS (p = 0.03), tumor location (p < 0.001), extent of surgical resection (p < 0.001) and radiotherapy (p = 0.01) were significantly associated with longer survival rates by univariate analysis. Multivariate analysis also showed a significant correlation between radiation therapy after surgical removal and survival time (p < 0.001). p53 status was not of importance in determining the necessity for radiotherapy. Radical surgical removal is the most important factor in the management of low-grade astrocytomas. Radiation therapy appears to be effective in improving the prognosis regardless of the extent of surgical resection or the p53 status.