Illness-induced context aversion learning in rats with lesions of the dorsal hippocampus

In 2 experiments, rats with electrolytic lesions of the dorsal hippocampus and sham-operated control subjects were given injections of lithium chloride after exposure to a distinctive context. This procedure establishes a context-illness association in intact subjects. In Experiment 1, the strength of the context aversion was assessed by measuring the subjects' willingness to consume a novel flavor in the context. It was found that lesioned subjects showed less suppression of consumption than controls. Experiment 2 tested the ability of the context to block subsequent flavor-aversion learning and revealed less effective blocking in lesioned rats. These results are consistent with the view that hippocampal lesions retard context conditioning; unlike previous work that has made use of conditioned freezing as the measure of context conditioning, the present results are not explicable in terms of lesion-induced changes in general activity.     

Antibodies against double-stranded DNA and development of polymyositis during treatment with interferon

Alpha interferons have become effective palliative treatments for patients with neuroendocrine tumours such as carcinoids and endocrine pancreatic tumours. However, several reports indicate an increased incidence of both autoantibodies and autoimmune diseases in patients treated with interferon-alpha (IFN-alpha). We studied the development of antibodies against double-stranded DNA (dsDNA) and clinical signs of autoimmune disease in 214 patients with malignant carcinoids or endocrine pancreatic tumours consecutively admitted for treatment with IFN-alpha. Seventeen patients (8%) developed antibodies against dsDNA, predominantly females (12 females and 5 males). One patient had clinical and laboratory signs of polymyositis. Among the other 16 patients, three developed hypothyroidism and in six patients the anti-dsDNA autoantibodies normalized despite continuing therapy. Although a significant number of patients developed autoantibodies against dsDNA, overt autoimmune disease related to these antibodies is a rare event and many patients spontaneously normalize these titres despite continuing IFN-alpha treatment.     

The effects of extracellular pH and calcium manipulation on protein synthesis and response to anoxia/aglycemia in the rat hippocampal slice

Extracellular pH modulates the function of the N-methyl-D-aspartate (NMDA) receptor, which may influence pathophysiological responses to glutamate. While damage due to oxygen and glucose deprivation or glutamate exposure is attenuated by acidification of the incubating medium of cultured neurons, neuron damage is enhanced in vivo following ischemia in hyperglycemic animals. A persistent inhibition of protein synthesis (to less than 5% of normoxic levels) is a reliable index of damage to neurons both in vivo and in the rat hippocampal slice. We explored the influence of extracellular pH and calcium manipulation on protein synthesis inhibition and energy failure due to anoxia/aglycemia or exposure to N-methyl-D-aspartate in the rat hippocampal slice. Moderate acidification of the medium during anoxia/aglycemia did not reduce the damage to protein synthesis in hippocampal neurons (9% of normoxic levels) and did not alter basal ATP levels or the rate of ATP depletion during anoxia/aglycemia. However, when calcium levels were lowered during the acidification and following the anoxia/aglycemia, protein synthesis was almost completely protected (84% of normoxic levels). Calcium reduction itself also attenuated the protein synthesis inhibition due to anoxia/aglycemia (to 55.6% of normoxic controls), but the protection was not as complete. In contrast, moderate acidification of the medium significantly reduced the damage to protein synthesis due to a brief exposure to NMDA (37% of control with NMDA, 78.9% of control with acidification during NMDA), even in the presence of extracellular calcium. Alkalinization of the medium exacerbated the protein synthesis inhibition following anoxia/aglycemia, and significantly reduced basal ATP levels (to 52% of normoxic control levels). Thus, pHo changes influence neuronal metabolism and response to anoxia/aglycemia. In addition, while acidification can reduce the excitotoxic damage caused by direct exposure to NMDA, it cannot reduce damage due to anoxia/aglycemia unless calcium is lowered concomitantly. Thus, both NMDA receptor activation and calcium are involved in the damage due to oxygen and glucose deprivation in the slice.     

Selective inactivation of alpha-ketoglutarate dehydrogenase and pyruvate dehydrogenase: reaction of lipoic acid with 4-hydroxy-2-nonenal

Previous research has established that 4-hydroxy-2-nonenal (HNE), a highly toxic product of lipid peroxidation, is a potent inhibitor of mitochondrial respiration. HNE exerts its effects on respiration by inhibiting alpha-ketoglutarate dehydrogenase (KGDH). Because of the central role of KGDH in metabolism and emerging evidence that free radicals contribute to mitochondrial dysfunction associated with numerous diseases, it is of great interest to further characterize the mechanism of inhibition. In the present study, treatment of rat heart mitochondria with HNE resulted in the selective inhibition of KGDH and pyruvate dehydrogenase (PDH), while other NADH-linked dehydrogenases and electron chain complexes were unaffected. KGDH and PDH are structurally and catalytically similar multienzyme complexes, suggesting a common mode of inhibition. To determine the mechanism of inhibition, the effects of HNE on purified KGDH and PDH were examined. These studies revealed that inactivation by HNE was greatly enhanced in the presence of substrates that reduce the sulfur atoms of lipoic acid covalently bound to the E2 subunits of KGDH and PDH. In addition, loss of enzyme activity induced by HNE correlated closely with a decrease in the availability of lipoic acid sulfhydryl groups. Use of anti-lipoic acid antibodies indicated that HNE modified lipoic acid in both purified enzyme preparations and mitochondria and that this modification was dependent upon the presence of substrates. These results therefore identify a potential mechanism whereby free radical production and subsequent lipid peroxidation lead to specific modification of KGDH and PDH and inhibition of NADH-linked mitochondrial respiration.     

Plasma von Willebrand factor changes during various reproductive cycle stages in mixed-breed dogs with normal von Willebrand factor and in Doberman pinschers with type-I von Willebrand''s disease

The immediate effects of oxidized low density lipoprotein (OxLDL) on the metabolic activity of cultured macrophages (RAW 264.7) were studied using a microphysiometer. Administration of OxLDL acutely induced a concentration-dependent increase in metabolic activity, with an EC50 of 16 +/- 3 microg/ml OxLDL and a maximal effect of 35% +/- 4% (mean +/- SEM; n=5). A biphasic response was measured after administration of 75 or 100 microg/ml OxLDL consisting of an initial sharp increase, followed by the induction of a long-lasting hypoactivity of 80% of the control value. Incubation of cells with polyinosinic acid (polyI; 100 microg/ml) for 30 min prior to OxLDL administration could completely block the effect of 25 microg/ml OxLDL. In addition, polyI acted as a full antagonist on the decrease of the biphasic response of cells generated by 75 and 100 microg/ml OxLDL. Macrophages used in this study possessed a specific binding site for OxLDL, with a dissociation constant (KD) of 9 +/- 2 microg/ml and a maximal binding of 610 +/- 32 ng 125I-OxLDL/mg cell protein. Binding of 125I-OxLDL to macrophages could be completely competed for by unlabeled OxLDL, by polyI for 58%, and by AcLDL for 46%. In conclusion, OxLDL can acutely activate the metabolic state of macrophages by a receptor-mediated process in a concentration-dependent fashion, which could be antagonized by polyI. Metabolic responses to OxLDL may underlie the changes observed in macrophages in the early atherosclerotic plaque.     

Post-traumatic first metatarsal reconstruction using coralline hydroxyapatite

Amination of 3,17 beta-Bis[(2-trimethylsilylethoxy) methoxy]-1,3,5(10)-estratriene-6-one (2) using NaCNBH4 and NH4OAc afforded 3,17-bis(SEM)-6-aminoestradiol (3) as a mixture of alpha and beta-isomers in 60:40 ratio. Hydrolysis of the mixture of 3 using HF and separation by preparative high-performance liquid chromatography afforded pure 6 beta-aminoestradiol (4) in good yield. The relative stereochemistry of the amino group in 4 was established by NMR. The biotinylated estradiol probe (7), chemiluminescent probe (9), and fluorescent probe (11), were prepared from 6 beta-aminoestradiol (4) and the corresponding biotin, 10-(3-sulfopropyl)-N-tosyl-N-(3-carboxypropyl)acridinium-9-carboxamide, and 5-carboxyfluorescein N-succinimidyl esters in 43-63% yields and > 99% purity.     

Paraumbilical vein in the cirrhotic patient: imaging with 3D CT angiography

This article provides a response to Stone's review and analysis of the scaffolding metaphor as it is applied to research applications for students with learning disabilities. We propose that, to advance the field of instructional research with students with learning disabilities, all available literature should be used when interpreting findings for instructional procedures for students with learning disabilities. Only when all of the intervention research literature in learning disabilities is examined can reliable conclusions be drawn regarding the efficacy of instructional procedures.     

The interactions between highly de-N-acetylated chitosans and lysozyme from chicken egg white studied by 1H-NMR spectroscopy

We have investigated the binding interactions between highly de-N-acetylated chitosans and lysozyme from chicken egg white by one-dimensional and two-dimensional 1H-NMR spectroscopy. A fully de-N-acetylated chitosan (fraction of N-acetylated units, F < 0.001) induced no observable changes in the 1H chemical shifts of lysozyme. However, a chitosan with F(A) = 0.04, where the N-acetylated units are predominantly surrounded by de-N-acetylated units (a monoacetylated sequence), induced significant shifts of several lysozyme resonances, demonstrating a specific interaction between lysozyme and de-N-acetylated units in the chitosan. The interaction between the two positively charged molecules increased with increasing ionic strength, as expected. The dissociation constant (Kd) between lysozyme and the monoacetylated sequence was strongly dependent on pH* (pH measured in D2O), with Kd = 0.02+/-0.01 mM at pH* 6.0, Kd = 0.11+/-0.02 mM at pH* 4.5, and Kd approximately 2 mM at pH* 3, suggesting that electrostatic forces contribute to the observed binding. The complex was strikingly stable, with bound lifetimes in the range of 10-25 ms at pH* 4.5 and 328-300 K. Most lysozyme resonances that were affected by the binding were assigned, and we suggest that the monoacetylated chitosan sequence binds to the active site cleft of lysozyme with the N-acetylated unit in subsite C. Assuming this binding mode, we have discussed the contributions in energetic terms from individual subsites of lysozyme towards binding of N-acetylated and de-N-acetylated units.     

Solitary choroidal metastasis as the first sign of metastatic lung carcinoid

The identification of malignancies associated with transplantation has led to enhanced vigilance and care in these patients, as well as insight into the pathogenesis of select malignancies. We report a case of Merkel cell carcinoma, an uncommon cutaneous malignancy of neuroendocrine origin, diagnosed in a 65-year-old Caucasian man 6 years after renal transplantation. While it is well known that transplant patients are at increased risk for squamous cell carcinomas of the skin, other types may also have an increased frequency. We suggest that Merkel cell carcinoma could have an increased incidence in the transplant population.