Total histamine degradation capacity (THDC) as an important biological marker of histamine metabolism in human colonic mucosa

Inflammation Research -     

MR imaging of focal splenic tumors

This study was undertaken to define the MR appearance of splenic tumors in 16 cancer patients with focal splenic lesions; 50 volunteers and liver cancer patients without splenic abnormalities served as controls. In 14 patients with focal splenic lesions, differences between splenic and lesion signal intensities permitted detection of splenic lesions on MR images, either because of cystic or necrotic areas lengthening T2 within the tumor, because of T1 shortening from tumor-associated hemorrhage, or because of T2 shortening of surrounding spleen in two cases of suspected transfusional iron overload. In one spleen, a lesion appeared isointense on both T1- and T2-weighted pulse sequences and was detected only by gross splenic deformity. In one other case, CT defined splenic metastases not visible on MR images. Measurements of signal intensity of normal spleens and tumor are so similar that spin-echo MR imaging can underestimate the size and extent of focal splenic disease or may miss lesions entirely. We conclude that MR imaging is a less sensitive technique for detecting focal lesions of the spleen than for detecting focal hepatic lesions.     

Effects of hyperthermia on the intracellular pH and membrane potential of Chinese hamster ovary cells

The effects of hyperthermia (exposure to 41-47 degrees C) on the intracellular pH and membrane potential have been studied using Chinese hamster ovary HA-1 cells. Our goal was to determine whether intracellular pH changes or changes in membrane potential correlated with cell killing. The intracellular pH (pHi) was measured using the DMO partitioning technique. A rapid acidification of the intracellular environment was observed at all the elevated temperatures studied. The pHi reached a plateau value of approximately 6.9, and started reversing towards normal values upon prolonged exposure to heat. Similar patterns were seen for delta pH (pHi-pHo). The membrane potential difference (delta psi) was measured using the fluorescence quenching of 3,3-dipropylthio-carbocyanine, and calibrated using a 86Rb+ diffusion potential. We found that delta psi falls to zero only upon prolonged exposure to temperatures above 43 degrees C. When the external pH was changed from normal values the drop in delta psi occurred more readily. Development of thermotolerance resulted in an increase in the time required to make delta psi change by half. The changes in delta psi were shown to be irreversible. When the proton electrochemical gradient (delta mu H+) was calculated using the measured values of delta psi and delta pH, the trends observed were the same as those seen for delta psi. The changes observed for pHi can be accounted for by the changes in the pK values of the components involved in the intracellular buffering. The changes in delta psi and delta mu H+ may reflect the physical breakdown of the transmembrane H+ gradients, which may be the actual mechanical process of cell death. No correlation of cell survival with the measured parameters was observed.     

Nerve biopsy findings in Niemann-Pick type II (NPC)

The severe infantile form of Niemann-Pick disease type II was diagnosed in a 4-year-old girl and confirmed by demonstrating in cultured skin fibroblasts a deficiency of low-density lipoprotein-stimulated cholesterol ester synthesis of < 5% of normal. Electrodiagnostic studies revealed changes of a predominantly demyelinating motor and sensory polyneuropathy. Light microscope and ultrastructural examination of a peroneal nerve biopsy showed unique changes. Compacted myelin sheaths were disproportionately thin with marked globular irregularities in single teased nerve fibres and evidence of chronic demyelination. The majority of axons were preserved but axonal spheroids and cytoskeletal abnormalities akin to neuroaxonal dystrophy were noted. Membrane-bound multilobulated lysosomal inclusions of floccular and electron-dense material were present in Schwann cells (SC), endoneurial fibroblasts, macrophages, pericytes and endothelial cells. SC of myelinated fibres were stuffed with whorls of concentric osmiophilic membranous profiles and electron-lucent material. The findings are diagnostic and differ from those of classical Niemann-Pick disease.     

Membrane lipids of B16 melanoma cells and heat-resistant variants

Membrane lipid composition and fluidity of a series of B16 melanoma cell variants with increased resistance to heat were analysed for changes within the lipid component that may contribute to the acquisition of heat resistance. Within one series of heat-resistant lines the cholesterol content of the cells decreased as their heat resistance increased. The most heat-resistant line, WH75, had 40 per cent less cholesterol than the parent line. No change in the composition of phospholipid fatty acids was found. An increased level of membrane fluidity in WH75 was demonstrated by electron paramagnetic resonance using 5- or 12-doxyl stearic acid. When challenged by heat the increase in membrane fluidity was similar for WH75 and for the parent line. Thus the increased heat resistance of the variants is probably not due to their ability to adapt to heat challenge by increasing membrane thermostability. The inverse relationship between heat resistance and cholesterol content was not demonstrated in two other series of heat-resistant variants. The cholesterol decrease, therefore, is not a universal response of cells as they acquire heat resistance.     

Anti-phospholipid and anti-DNA antibodies are not associated with the elevated release of circulatory fetal DNA in pregnancies affected by preeclampsia.

OBJECTIVES: We have previously shown that the levels of circulatory fetal DNA are elevated in preeclampsia and that these increases correspond to disease severity. Several reports have indicated that increased levels of antiphospholipid (anti-PL) and anti-DNA antibodies may be associated with preeclampsia, in particular with the severe forms of the disorder. Since the release of cell-free DNA by the placenta is attributed to some form of cell death or damage and as anti-PL and anti-double-stranded DNA (dsDNA) antibodies have been proposed to lead to placental damage, we have studied the relationship between these parameters in preeclampsia. METHODS: Circulating fetal DNA levels in samples taken from pregnant women with mild (n = 12) or severe (n = 12) preeclampsia and from normal pregnant controls (n = 35) were quantified using a Taqman real-time Polymerase Chain Reaction (PCR) assay. The Anti-PL antibodies (IgG and IgM) were assayed by anticardiolipin ELISA and by commercial anti-beta2-Glycoprotein I (GPI) ELISA kits. Anti-dsDNA antibodies (IgG and IgM) were analyzed by a commercially available anti-dsDNA ELISA kit. RESULTS: No correlation could be drawn with the quantity of circulatory fetal DNA in the samples analyzed and corresponding anti-PL or anti-dsDNA antibody levels. Furthermore, no significant difference existed between the levels of these antibodies in the two study groups and the control cohort. CONCLUSION: Our data suggest that the mechanism leading to the increased release of cell-free circulatory DNA from the placenta does not involve trophoblast damage mediated by these agents. Our analysis also questions the reported involvement of anti-PL and anti-DNA antibodies in preeclampsia.